Dissertations/Thesis

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2024
Dissertations
1
  • BEATRIZ SOARES DE SOUZA
  • Application of Graph Theory in the Analysis of Query Similarity and Complexity in Relational Databases

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • DANIEL GOUVEIA COSTA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jan 31, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Information Systems constant changes and refactoring processes eventually result in design debts, one of them being related to the database management. Redundancy and complexity are often found in databases and eventually affect the overall system performance. In this study, the analysis conducted was based on graph analysis, which is an essential technique in several fields demanding data management. The investigation involved the study of relationships and connections in a real-world financial organization database, between SQL queries represented as nodes and edges in a graph structure. By analyzing the graph structure and properties, it was possible to identify important nodes, detect clusters of related data, and uncover hidden relationships and redundancy. The results indicate that 50% of the database queries had medium to high similarity in subgraphs, which allows the organization to gain valuable insights into their data, make informed decisions, and optimize their database performance.

2
  • DANIEL SILVA DE MORAIS
  • Identification, Control and Prediction Techniques applied to Differential Wheeled Robots

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • CARLOS EDUARDO TRABUCO DOREA
  • FILIPE CAMPOS DE ALCANTARA LINS
  • PABLO JAVIER ALSINA
  • Data: Feb 16, 2024
    Ata de defesa assinada:


  • Show Abstract
  • This work presents the identification, control, filtering and prediction of a two-wheeled differentially-driven mobile robot. For this, the variable substitution methodology will be used in the mathematical model of the robot, with its position variables, represented in the Cartesian coordinate system, replaced by its linear displacement. As the model becomes essentially linear, without the use of linearization techniques, classic control approaches, such as PID, can be used, as well as the use of predictors and filters. For the identification of the model, real experiments were performed for data collection and the least squares method was used for different structures considering the order and delay time. Using Akaike information criterion and real robot reaction experiments, it was possible to choose a model that best represents it. Decoupling the system from the robot is proposed to reduce the unwanted cross relationship that exists between inputs and outputs. It is also proposed to use the Smith Predictor and Kalman Filter to minimize the delay time and estimate the filtered values of linear displacement and orientation, respectively. Finally, some identified models and the execution schedule for the completion of this work will be demonstrated.

3
  • MARIA DA GUIA TORRES DA SILVA
  • Educational Robotics as a Pedagogical Resource for Students with Learning Difficulties

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • CARLA DA COSTA FERNANDES CURVELO
  • LUCIANE TERRA DOS SANTOS GARCIA
  • LUIZ MARCOS GARCIA GONCALVES
  • SARAH THOMAZ DE SA ROSSITER
  • Data: Feb 19, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The use of Educational Robotics as a support tool in the teaching-learning process for children with learning difficulties is the core of our investigation. In this work, we try not to distinguish between (normal) difficulties caused by lack of interest or another solvable problem in the classroom or those caused by well-defined disorders in medicine. In an initial systematic review, in which we did a general search of articles and dissertations in conferences and journals using a well defined set of keywords that covered the most well-known learning problems and that also met the keyword "educational robotics", we identified that there are very few works on this topic, around 14 contributions. Given the novelty of the topic, we carried out a more in-depth analysis of these and other works, including several issues, not only related to learning difficulties. Our main question to be answered, from then on, was to identify how much and how educational robotics can be an adjunct in the teaching-learning process, for these students with difficulties. With this in mind, we defined the quali-quanti research methodology to identify the remaining points, where we adopted questionnaires as a data collection instrument. We provide forms with questions for students, teachers, and monitors from selected schools, among those that have educational robotics activities (all public schools) in the city of Natal, RN, Brazil. Through an analysis of the data obtained from the forms, we observed an increase in the use of robotics in education, in general. However, we mainly identified that, although students with learning difficulties or disorders are found in educational institutions, they are not completely included in robotics activities. Nonetheless, after compiling and analyzing the data, we reached positive results, which verify the possibility of application to improve learning in these children. That is, the majority of students and a good number of teachers and monitors agree that robotics has managed to improve the ability of students with difficulties in learning, especially transversal content. Regarding "how", we noticed that some factors are important. The first factor is the ease of understanding the robotics itself, brought about by new software and hardware tools developed by this pretty new scientific community, which greatly facilitate its use as a support tool. Furthermore, we note that the interest of teachers is another factor in the "how" that can collaborate in trying to improve the issue of learning difficulties. We noticed that interest improves with the use of these new tools, demystifying robotics, which is no longer a big deal for lay teachers. Furthermore, the existence of complete support systems for its application, free of charge and freely available, involving content and tools on the Web, in addition to an effective continuing education policy for teachers, have contributed to the tool becoming increasingly more effective, mainly, as highlighted, in content transversal to robotics.

4
  • MATEUS ARNAUD SANTOS DE SOUSA GOLDBARG
  • Aware Compression of Deep Neural Network Models Based on Pruning Followed by Quantization.

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • ALLAN DE MEDEIROS MARTINS
  • SERGIO NATAN SILVA
  • FLAVIA MARISTELA SANTOS NASCIMENTO
  • MARIA GRACIELLY FERNANDES COUTINHO
  • Data: Feb 20, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Deep learning techniques, particularly deep neural networks (DNNs), have been successfully employed in numerous problems. However, these types of algorithms demand substantial computational effort due to the large number of parameters and mathematical operations involved, which can pose challenges for applications with limited computational resources, low latency requirements, or low energy consumption. Thus, this work proposes the application of a novel training strategy for the conscious compression of DNN models based on pruning, quantization, and pruning followed by quantization, capable of reducing processing time and memory footprint. The compression strategy was applied in two domains: the first for automatic modulation classification, where the model size was reduced by 13 times, maintaining an accuracy only 1.8% lower than the uncompressed model. In the second domain, focused on image classification in microservices environments, the same compression strategy was applied. In this context, a 7.6-fold reduction in model size was observed, with accuracy close to the uncompressed model. Furthermore, the implementation of these techniques reduced prediction latency by 1.7 times and significantly decreased the time required for the deployment of microservices containing these models. These results underscore the effectiveness of the proposed approach, indicating its potential positive impact in scenarios that require computational efficiency and resource conservation.

5
  • EDUARDO NUNES VELLOSO
  • End-to-End Optimization of Multiuser MIMO Systems Using Autoencoders with Bidirectional Channel Estimation

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCELO SAMPAIO DE ALENCAR
  • Waslon Terllizzie Araujo Lopes.
  • Data: Mar 21, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The spectral efficiency gains introduced by multiuser MIMO systems render them relevant schemes for current and upcoming generations of mobile communication networks. Due to the intrinsic complexity of the mathematical models of these systems under realistic conditions and the interdependence between the processing steps of the transmitters and receivers, machine learning is an option that allows the complete system to be designed by training a noisy autoencoder. This paper proposes a neural network architecture for end-to-end optimization of a multiuser MIMO system. The performance of the system, measured in terms of symbol error rate, was compared to an M-PSK baseline with zero-forcing equalization and least-squares channel estimation. Simulations were performed using a Rayleigh fading channel model and the realistic 3GPP TR 38.901 model. A bidirectional channel estimator, based on the interpolation of sparse pilots, is proposed, reducing the control signaling to less than 3% in exchange for a fixed 10 ms delay. The results show that signicant gains can be achieved by applying the proposed model, but those vary with respect to the estimation errors during the pilot transmission times.

6
  • ANTONIO ALCIR DE FREITAS JUNIOR
  • Detection of Distributed Denial of Service Attacks using Convolutional Neural Network.

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • FRANCISCO SALES DE LIMA FILHO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • Data: Apr 16, 2024


  • Show Abstract
  • With the expansion of the Internet, combined with the growing number of Internet of Things (IoT) devices, denial of service attacks (Denial of Service - DoS), as well as its distributed variant (Distributed Denial of Service - DDoS), have become more widespread, making it a significant problem for the availability of services operating on the Internet. In recent years, the number of research in academia and industry on the detection and mitigation of these attacks has been growing, but without a definitive solution yet. Techniques involving machine learning are being widely used to detect and mitigate these attacks. Although efficient, the proposed techniques present a high computational cost, which may make them unfeasible in network scenarios with intense data flows, due to the temporal restrictions imposed by real-time processing of the data flow. Inspired by these works in the literature, but seeking to reduce computational complexity, this work proposes the use of a low-complexity convolutional neural network to detect DDoS attacks. The complexity reduction of the proposed convolutional network is based on the use of descriptors obtained from a set of metrics calculated on sampled network traffic header data. The developed method has a high success rate, low false positive rate, and relative simplicity of implementation, making it suitable for the task of detecting DDoS attacks in network scenarios with high throughput.

Thesis
1
  • MAURÍCIO RABELLO SILVA
  • Data Transport Protocol for FANET in Rocket Impact Area Scanning over the Sea by Unmanned Aerial Vehicles

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • CARLOS MANUEL DIAS VIEGAS
  • FELIPE DENIS MENDONCA DE OLIVEIRA
  • FRANCISCO ARY ALVES DE SOUZA
  • MARCELO BORGES NOGUEIRA
  • PABLO JAVIER ALSINA
  • Data: Feb 23, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Systems involving multiple Unmanned Aerial Vehicles (Multi-UAVs) performing area scanning procedures have garnered attention in recent years. Developing these systems faces significant challenges, with the robustness of the data communication network being a crucial aspect for efficient collaboration among UAVs. This work is dedicated to specifying a data transport protocol for a communication network within a squadron of Unmanned Aerial Vehicles, focusing on scanning the rocket impact area over the sea in the SPACEVANT 2 project.

    The research encompasses the key characteristics of communication networks for multi-UAV systems, considering application-specific aspects such as path and trajectory planning and sensor data collection. Strategies are proposed for the rocket impact area scanning, analyzing characteristics of networks best suited for these strategies, and defining a suitable protocol for the application. Utilizing Xbee Pro 900HP S3B modules in a network architecture integrated with a computer-controlled embedded hardware platform, a test plan is devised and implemented to assess the protocol's performance. Performance evaluations include measurements of bandwidth (throughput), latency, and indicators on communication links among network nodes, such as retransmission, packet loss, flow control, and congestion. This study demonstrates the robustness and reliability of the protocol in the proposed network architecture for multi-UAV systems.

2
  • RUTE SOUZA DE ABREU
  • Enhancing Fault Prediction in Redundancy Models: A novel approach using Generalized Stochastic Petri Networks and Spiking Neural Networks

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • DANIEL GOUVEIA COSTA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • JUAN MOISES MAURICIO VILLANUEVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • RENAN CIPRIANO MOIOLI
  • Data: Feb 29, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Fault prediction plays an important role across several sectors such as industry, technology, medical sector, among others. This task can help in the reducing of equipment maintenance costs, prevention of accidents and disasters, and improvement of system dependability since it can increase availability by reducing system downtime. This work presents a methodology for fault prediction in redundancy models designed using the formality of Generalized Stochastic Petri Networks. The approach comprehends the steps of modeling and simulation of systems with active and passive redundancy under different fault scenarios, such as non-perfect switches, standby failures, and common cause failures, as well as fault datasets generation and the implementation of a machine learning model for performing the fault prediction. For forecasting, this research utilizes Spiking Neural Networks (SNNs), which have been recognized as the third generation of Artificial Neural Networks. Just like typical artificial neural networks, SNNs draw inspiration from the biological dynamics of the brain, incorporating the interconnected topology of neurons into their architecture. However, while conventional neural networks rely on error minimization by weight adjustment, SNNs aim to replicate the learning process by simulating neuron behavior by taking into account elements of the biological process such as synapse, energy accumulation, electric impulse firing, and refractory periods between emissions. Due to the ability to capture temporal aspects from data, SNNs are vastly used in problems with time dynamics. Additionally, literature has shown these networks to be task and energy-efficient serving as a low-cost alternative compared to conventional ANNs.

3
  • YURI THOMAS PINHEIRO NUNES
  • Concept Drift Detection Heuristic Based on TEDA

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • MARCELO AUGUSTO COSTA FERNANDES
  • IGNACIO SANCHEZ GENDRIZ
  • JUAN MOISES MAURICIO VILLANUEVA
  • Data: Apr 16, 2024


  • Show Abstract
  • The enormous amount of machine learning applications and data produced presents several challenges today. In many contexts, data may have temporal relevance, for example, seasonality and trends, resulting in non-stationary behavior. This characteristic present in several systems makes it difficult to apply machine learning models, which, in general, assume that the data is stationary. In this scenario, data sources can be considered as data streams: ordered and unlimited sources of non-stationary data. These sources feed machine learning applications unreliably because they violate stationarity. When the data stream presents a significant variation that could lead to performance degradation, it is said that a concept drift has occurred. A data stream that presents concept drift is considered to represent an evolutionary system (evolving system). A system that evolves, presenting changes in its internal concepts, for example, emergence of new concepts, extinction of concepts, division and fusion of concepts, etc. In this context, machine learning techniques must be adapted to the context of data streams. An example would be a classifier for data stream samples (data stream classifier). This type of model needs to consider real-time retraining, robustness to non-stationarity, data unavailability, and limited data set, among others. To implement these different characteristics, it is essential to use concept drift (CDD) detectors. CDDs are not models capable of identifying when one or more concepts in the data stream have changed significantly. The literature is rich in works on concept drift detection distributed into three groups: supervised, semi-supervised, and unsupervised. Supervised methods have access to the true classes of data stream samples at the time of detection, while semi-supervised methods have limited access. Semi-supervised methods can have access to the true classes during training, during offline steps, or even to a subset of samples at the time of detection. Unsupervised methods do not access the true classes of the samples, being theoretically more limited than other approaches. However, unsupervised methods allow for shorter detection delays in real applications, as it is reasonable not to have access to the true class at the time of detection. Examples of unsupervised methods are ADWIN, KSWIN, and PageHinkley. This work presents a new concept drift detection method, TEDA-CDD. This detector is composed of two models to represent concepts based on TEDA: the reference model and the evolutionary model. The reference model represents the concept known to the machine learning model, while the reference model is free to adapt to any new model that emerges from the data stream. The models are compared heuristically using the Jaccard index to indicate similarity. When the index indicates low similarity between the models, the detector indicates a concept drift. To compare the proposed method with other methods present in the literature, initially, a realistic approach for data stream classifiers is proposed. This approach makes it possible to apply several classifiers and detectors to the data stream classification task and estimate performance metrics specific to the data streams context. In the experiments, the proposed method is compared to other methods present in the literature using synthetic and real benchmarks. The proposed method has comparable performance in terms of accuracy compared to methods consolidated in the literature, while it is the most efficient in terms of memory consumption.

2023
Dissertations
1
  • IRLETE PEREIRA MOTA ALVES
  • Optimization of the Speed Vector Control Drive of a Three-Phase Induction Motor without Split Winding Bearings

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • JOSSANA MARIA DE SOUZA FERREIRA
  • JOSÉ ÁLVARO DE PAIVA
  • RICARDO FERREIRA PINHEIRO FILHO
  • Data: Mar 3, 2023
    Ata de defesa assinada:


  • Show Abstract
  •  
    The objective of vector control is to guarantee a fast speed response even with high torque for induction machines, both in transient and steady state. To implement a speed control in a three-phase induction motor without bearings with split winding, three phases are normally used to control the currents. This standard procedure requires a complete drive structure, containing the three arms, with various power electronics.

    The strategy presented in this work consists of controlling only two of the three available currents, obtaining the third through the sum of the two previous ones. With this change, only two inverter arms are needed, considerably reducing the electronic components used. For this implementation, an induction bearing motor working in the vertical position was used.
2
  • JULIANA OLIVEIRA DE MEDEIROS
  • Use of the Particle Swarm algorithm to estimate the error introduced by TIs in calculating the fault location distance using fundamental frequency phasors

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • FLAVIO BEZERRA COSTA
  • JOSE TAVARES DE OLIVEIRA
  • MELINDA CESIANARA SILVA DA CRUZ
  • ROANA D' ÁVILA SOUZA MONTEIRO
  • Data: Mar 10, 2023
    Ata de defesa assinada:


  • Show Abstract
  • An Electric Power System (EPS) has the basic function of providing consumers with a continuous and quality product. For this, performance standards specified by ANEEL (National Electric Energy Agency) must be complied with by the concessionaire companies, in such a way as to guarantee the reliability of the energy supply and the conformity of voltage levels when disturbances occur and during operation. normal on a permanent basis. Thus, it ensures that the energy system will be able to keep working for a longer time, inhibiting failures due to equipment wear and avoiding the occurrence of financial losses. In order to meet reliability and quality requirements, the electrical system operation centers have data servers with oscillographic records from relays, oscillographs and qualimeters installed in the system's substations. These files are normally used for various functions, such as protection or power quality analysis. With regard to power quality, oscillographic records are normally used to classify disturbances in the electrical network.
    From a protection point of view, the files are often used for post-operation analysis of the proper functioning of protective relays or for fault location algorithms. Therefore, it is essential that the records have a reliable time base, so that they can be considered synchronized, when more than one record is needed in a specific algorithm. Even considering that efficient algorithms for synchronizing records and locating faults are available, it is not possible to find in the literature an algorithm to estimate the error produced in the process of calculating the fault distance, a calculation performed according to the methodology that adopts phasors from the fundamental frequency.
    It is noteworthy here that the oscillographic records available for calculating the phasors come from sampling signals, collected by means of TPs and CTs (TIs), which inherently have relation and phase errors, which depend on the accuracy class of these instruments. In addition to those related to TIs, other errors can be introduced by the sampling process or composition of the representative phasors of the sampled signals. Thus, it is necessary to develop an algorithm to estimate the error produced in determining the fault distance, even if this distance has been determined from reliable algorithms for synchronizing the records and locating the fault. In this Dissertation, we propose an algorithm based on Particle Swarm (PSO) to meet this purpose.

3
  • EVELYN CRISTINA DE OLIVEIRA LIMA
  • PROGRAMMABLE BANDPASS SIGMA-DELTA MODULATORS USING N-PATH FILTERS

  • Advisor : DIOMADSON RODRIGUES BELFORT
  • COMMITTEE MEMBERS :
  • DIOMADSON RODRIGUES BELFORT
  • FRANCISCO DE ASSIS BRITO FILHO
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Mar 15, 2023
    Ata de defesa assinada:


  • Show Abstract
  • In Software Defined Radio (SDR) most analog functions such as downconversion and channel selection are moved into the digital domain. With these features, an SDR can be easily programmed and adapted to new standards. However, its implementation using a Nyquist rate analog-to-digital converter (ADC) has been challenging and very power-hungry, which makes it unsuitable for mobile applications. SDM (Sigma-Delta Modulator) using LC resonators are well suited for this purpose, as they can convert a narrowband around a radio frequency (RF) center frequency. In the literature, high-order LC-based SDM uses nodes between LC tanks for feedforward or feedback coefficients, to obtain the desired noise transfer function (NTF). These nodes are often an additional source of noise, non-linearity, and power consumption, affecting overall SDM performance. In this project, we aim to explore the functionality of N-Path filters to implement a programmable Sigma-Delta Bandpass Modulator that meets various communication standards. Therefore, it was necessary to carry out a bibliographic and technological research on the state of the art of N-path filters, continuous-time and discrete-time Sigma-Delta modulators. There was also the development of high-level models for different topology categories of Sigma-Delta Modulators implemented with LC and discrete-time filters to serve as comparison models with the topology design methodology using the N-path filter proposed in this work. A high-level model of the N-Path filter was developed, and the work is currently in the stage of integrating the N-path filter and SDM. The results obtained from the SDM implementation with LC filters show that the modulator has a good agreement with its DT equivalent. In initial experiments, the implementation of SDM with an RLC circuit equivalent to the N-path filter proved to be promising, presenting results similar to those obtained with the discrete-time topology.

4
  • FRANCINALDO DE ALMEIDA PEREIRA
  • Data Lake and Analytics platform for COVID-19 Data Analysis

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ALYSSON NASCIMENTO DE LUCENA
  • DAVI HENRIQUE DOS SANTOS
  • LUIZ MARCOS GARCIA GONCALVES
  • SARAH THOMAZ DE SA ROSSITER
  • Data: Apr 5, 2023
    Ata de defesa assinada:


  • Show Abstract
  • We propose to develop a platform consisting of a data lake, to be implemented as a web-based service. The main idea is that it can be used by data scientists working on COVID-19-related projects in order to access as much data as possible in one repository and be able not only to analyze that data but also to manage and contribute to new data. Through this platform, it will be possible to dynamically aggregate different data repositories related to the COVID-19 pandemic, in order to provide users, through a web interface, tools for use, transformation, and collaboration of data, as well as analysis and visualization tools integrated to geographic information systems.

5
  • RENAN ARAUJO DE LIMA
  • SOFTWARE TOOLS FOR BEHAVIORAL BOX FOR THE STUDY OF TACTILE DISCRIMINATION TASKS IN RODENTS

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ALMIR KIMURA JUNIOR
  • ANDOUGLAS GONÇALVES DA SILVA JÚNIOR
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Apr 12, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The area of Neurophysiology of Social Behaviors in Rodents has the general objective of investigating the electrophysiological correlates of social behaviors in rodents. Examples of studies in the area include the investigation of neural processing disorders and synaptic plasticity in animal models of autism and changes in synaptic plasticity in animal models of epilepsy. This area uses sophisticated and expensive equipment, and some of the existing platforms are proprietary brands, obsolete, and using old technology. There is a prominent need to improve this equipment to aid research, seek cheaper alternatives, with open construction, and use more up-to-date components. With that in mind, in this work, we propose improvements in the software platform that receives data and controls the necessary operations in the experiments using the behavioral box. Specifically, we contribute on three fronts. At first, we developed software aimed at automating a behavioral box in a tactile discrimination task, which, in its new version, uses the Arduino microcontroller. Also, we developed the software part of the Supervisory System, in Python, which communicates with Arduino, for visualization and definition of the tasks to be carried out in the behavioral box. Finally, we developed basic computer vision routines for locating the rodent within the behavioral apparatus, indicating its position and orientation. These developments collaborate so that the box can be automated, reducing manual interaction with the experimenter, and thus contributing to improving the process of studying tactile discrimination in rodents.

6
  • AZIZ OLOROUN - SHOLA BISSIRIOU
  • Contributions to Energy Management of Single Phase AC Microgrids Used in Isolated Communities.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ALEXANDRE CUNHA OLIVEIRA
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Apr 26, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Isolated communities require assistance to maintain a reliable power system that can provide an efficient power flow to their consumers, as they are often not connected to a bulk transmission systems. To meet local energy needs, small power systems, called microgrids, are created. Typically, these microgrids use Renewable Energy Resources (RESs) and Energy Storage Systems (ESSs) to control power flow and maintain energy quality within specified limits. However, due to the intermittency of renewable sources, particularly wind and solar, finding the appropriate topology and defining a power management system for these microgrids has been challenging. This dissertation presents a methodology to determine a suitable topology for a single-phase AC microgrid to provide power to the Adjarra/Benin community. Additionally, it proposes an energy management scheme to ensure a reliable energy flow, taking into account the minimum deployment and operation costs of the microgrid. Finally, the viability of microgrid operation under different scenarios is evaluated through simulation experiments.

7
  • PEDRO VICTOR ANDRADE ALVES
  • Proposal for a Real-Time Testing Platform Applied to Tactile E-commerce

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • ALLAN DE MEDEIROS MARTINS
  • LUCILEIDE MEDEIROS DANTAS DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • PATRICIA DELLA MÉA PLENTZ
  • Data: Jul 31, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This work aimed to develop a real-time test platform for systems associated with the tactile internet area. The proposal comprises a master device, a communication channel and a slave device. The master device is a tactile glove (wearable technology) that works as a tactile interface based on vibratory feedback, responsible for enabling interaction with virtual or remote elements. Additionally, the communication channel introduces a bidirectional connection of variable latency. In turn, the default slave device is a robotic Phantom Omni manipulator integrated with the Matlab/Simulink environment and the robotics toolbox. The platform can generate tactile sensations such as coarse roughness, fine roughness, smoothness, dripping and softness. Furthermore, the results of the proposal have been adequate and allow testing various algorithms and methods related to tactile internet.  Therefore, the developed system has the capacity to serve as a basis for a wide variety of use cases related to tactile internet, providing a diverse opportunity for exploration and application. In this sense, the proposed platform serves as a foundation for a use case focused on tactile exploration of product textures on an e-commerce website, enabling interaction with virtual clothing through online shopping capable of providing tactile stimuli. In the scenario of this use case, the slave device is a cursor that functions as an element controlled by the master device and a mouse, which allows interaction with different clothing textures, generating specific tactile sensations on the tactile glove. In order to enhance the platform performance, Virtual Network Functions (VNFs) were introduced. VNFs are virtualized processes implemented and executed in cloud services, capable of enhancing the scalability and agility of a network, while also enabling more efficient utilization of infrastructure resources. In Fifth Generation (5G) mobile networks, tactile internet connections are associated with ultra-reliable low-latency communications (URLLC) services. This category poses challenges due to its stringent requirements of low latency in a few milliseconds, low packet loss probability, and high network availability. Thus, the application of VNFs during tactile internet connections in 5G networks allows for adjustments of connection parameters to maintain good connectivity, ensuring the low-latency criterion and a high degree of realism in tactile interactions. Consequently, the use of VNFs in URLLC communications aims to fulfill the requirements of tactile internet systems while maintaining an acceptable level of Quality of Experience (QoE), which is a metric defined by the Telecommunication Standardization Sector as the degree of satisfaction or annoyance of users with an application or service.

8
  • JESSIKA CRISTINA DA SILVA
  • Performance Evaluation of Data Rate Adaptation Mechanisms for LoRaWAN networks for Scenarios of Livestock in Semi-Confinement

     

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • VALDEMIR PRAXEDES DA SILVA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Aug 1, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This work aims to investigate Adaptive Data Rate (ADR) mechanisms in LoRaWAN networks as a solution for dynamic IoT scenarios and also propose a new solution based on latter investigations. The standard ADR technique, defined in the LoRaWAN network protocol, is a simple technique that allows an adjustment of transmission rate by reading the SNR (Signal-to-Noise Ratio) value. Due to the multiplicity and dynamics of IoT scenarios, it is necessary to investigate ADR techniques that establish a good compromise between coverage and capacity. This thesis aims to investigate IoT scenarios of livestock in semi-confinement, especially in time-varying scenarios (emergence of concentrated traffic demand, network with mobile sensors, for example). Preliminary results using the ns-3 simulator demonstrate the need to dynamically adapt the ADR parameters, as each scenario requires different ADR strategies (or different parameterization of pre-existing strategies). Finally, we propose an adaptation of classic ADR algorithms to promote flexibility between coverage and capacity in such scenarios.

9
  • CASIMIRO WAETE AGOSTINHO
  • Automatic Orientation of Photovoltaic Solar Panels for Monitoring the Seasonal Movement of the Sun Using Intelligent Control

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • ROMÊNIA GURGEL VIEIRA
  • Data: Aug 9, 2023


  • Show Abstract
  • Solar trackers, besides serving as support for photovoltaic modules, follow the move- ment of the sun throughout the day and try to keep the plane of the photovoltaic modules perpendicular to the sun’s rays, thereby increasing the performance of the photovoltaic module. With the aim of demonstrating the effectiveness of using the automatic orien- tation method of photovoltaic solar modules in following the seasonal movement of the sun as a way of improving energy production, this work analyzes two systems: a solar tracker and a fixed-axis system. The first part simulates two photovoltaic plants with solar tracking and fixed-axis systems using the software PVsyst, consisting of a total of twenty modules. The results show that the solar tracker improved the efficiency of electricity production, with a gain of 25.97% during the day and an annual gain of 25.6% more than a fixed system. The second part presents a proposal for an automatic solar tracking system (with a controller) and a fixed-axis system (without a controller) based on the equations of the sun’s movement angles. This was modeled using the software Matlab/Simulink using Fuzzy logic as the controller, with the aim of evaluating the use of solar radiation throughout the day and to build a real system with the same characteristics as the pro- posed simulation. The gain of this system was approximately 17% to 35% during some hours of the day for the system with a controller. Both software simulations showed that photovoltaic systems that track the movement of the sun during the day and year are more advantageous compared to fixed-axis systems because they take better advantage of solar radiation.

10
  • ALEXANDRE HENRIQUE SOARES DIAS
  • Promoting Research Relevance: A Natural Language Processing-based Model for Identifying SDG-aligned Scholarly Publications

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • LIVY MARIA REAL COELHO
  • ALLAN DE MEDEIROS MARTINS
  • EDUARDO ALMEIDA SOARES
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • OLIVIA MORAIS DE MEDEIROS NETA
  • Data: Aug 31, 2023
    Ata de defesa assinada:


  • Show Abstract
  • In 2015, the United Nations established the 17 Sustainable Development Goals (SDGs) to promote environmental stewardship, economic advancement, and social equity. Within this framework, scientific research plays a pivotal role in addressing the challenges encompassed by the SDGs. An exemplary tool, SciVal, facilitates the correlation of scientific outputs with the SDGs through expert analyses. However, in order to mitigate the reliance on specialized expertise and offer a self-reliant solution, this endeavor proposes a natural language processing-based, deep machine learning-powered, multi-target classification model bolstered by interpretability techniques and good practices for the development and analysis of data streams.. The objective is to effectively map academic publications to the SDGs. By employing this proposed model, the vast potential of scholarly research can be harnessed, directly aligning it with the global agenda for sustainable development. Researchers, policymakers, and organizations can adeptly navigate the extensive landscape of research papers and identify those that harmonize with their specific areas of interest within the SDG framework. Over one million scientific publications were utilized to train and evaluate the model. The corpus encompassed publication titles extracted from the Scopus database, accessed via the SciVal tool, and annotated with respect to 16 of the 17 SDGs. To substantiate the efficacy of the proposed model, it was applied to associate publications from the Brazilian Automation Congress (CBA 2020) with the SDGs, thereby measuring the contribution of scientific endeavors in automation towards the attainment of the SDGs. The outcomes within the context of CBA 2020 revealed prevalent themes affiliated with SDGs 7 and 9, relating to clean energy and industrial innovation, respectively. Given the extensive training data and the comprehensive range of SDGs addressed, the model can confidently be deployed to correlate academic output from diverse domains with the SDGs.

11
  • JÚLIA DA LUZ ANDRADE SILVA
  • Measurement and Evaluation of Exposure to Non-Ionizing Radiation in Indoor Environments

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO DIONISIO DE ANDRADE
  • Data: Sep 22, 2023


  • Show Abstract
  • It is essential to monitor the levels of Non-Ionizing Radiation (NIR) that the general population may be exposed to and compare them with the limits defined in current regulations, bearing in mind the rapid rise of telecommunication services and the perspectives of an extremely connected. Indoor environments (\textit{indoor}), such as residences and shopping malls, are places that meet the interests of measurements, mainly due to the presence of different NIR sources and the location of these sources about end users. This work presents NIR measurements in a \textit{shopping center} and residences in Natal, RN, Brazil. At shopping, a set of six measurement points was proposed, following two criteria: places with a large flow of people and the presence of one or more Distributed Antenna System (DAS), co-located or not with Wi-Fi access points. The results are presented and discussed in terms of distance from the DAS (conditions: near and far) and flow density of people in the mall (scenarios: low and high number of people). The highest mean and highest peak electric fields measured were 1.96 and 3.26~V/m, corresponding respectively to 5\% and 8\% of the limits defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and Agency National Telecommunications Agency (ANATEL). In the homes, measurements were taken at 40 Wi-Fi access points where the highest exposure level was 4.66 V/m (7.64\% of the limit), verified for the network load on the network of 2.4 GHz (Situation 1), at a value of 4.66 V/m (7.64\% of the limit). The results are discussed regarding the measurement situation, brand and time of use of the equipment. Measurements were also carried out in 51 microwave ovens. Only one exceeded 50~W/m² (limit determined in current regulations), caused by rust that compromised the door's structure. Thus, two types of repairs were carried out: the use of epoxy putty to fill the opening in the door (Repair 1) and the replacement of the outer surface of the oven (Repair 2). Only Repair 1 solved the leakage problem with an average of 0.1841 W/m² and a peak of 0.4222 W/m². As for the other 50 microwave ovens, the relation between power density and factors such as worst point, brand, time of use and state of conservation of the device were analyzed.

12
  • ARTHUR DINIZ FLOR TORQUATO FERNANDES
  • Machine Learning Technics for the prediction of extreme overirradiance events

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DANIEL LOPES MARTINS
  • IGNACIO SANCHEZ GENDRIZ
  • SAMIRA DE AZEVEDO SANTOS EMILIAVACA
  • Data: Sep 22, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The current dissertation is centered on the forecasting of Overirradiance within intervals of up to five minutes, achieved through the utilization of machine learning methodologies. Overirradiance, a phenomenon characterized by solar irradiance surpassing anticipated values under clear-sky conditions at the Earth's surface, has generated scholarly interest within the sphere of solar energy research and its implications for photovoltaic power generation systems. To date, no dedicated studies investigating the application of Machine Learning techniques for forecasting this phenomenon have been identified.

    In pursuit of this aim, the performance of four distinct machine learning algorithms has been meticulously examined: Random Forest, Support Vector Machines (SVM), Multilayer Perceptron (MLP), and Long Short-Term Memory (LSTM) neural networks. The present study endeavors to bridge a lacuna in research by scrutinizing the feasibility and efficacy of these algorithms in predicting Overirradiance events, thereby augmenting the comprehension and pragmatic application of this phenomenon within solar energy systems.

13
  • TAYNÁ ARRUDA CÂMARA DA SILVA SALVIANO
  • An Approach for Generating and Visualizing Association Rules for Access to News Portal Content
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • DANIEL GOUVEIA COSTA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Dec 5, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This work aims to propose and validate an approach for the generation and visualization of association rules and sequence rules obtained from the content access history data of a Brazilian journal. The proposed approach is composed of four phases: exploratory data analysis (EDA), data preprocessing, generation of association and sequence rules, and visualization of results. The algorithmsAprioriand FP-Growth were used to generate the association rules. To generate sequence rules, the algorithm used was SPADE. Parallel coordinate graphs were used to visualize the association rules and graphs for visualization of sequence rules. An outstanding aspect of the proposed approach is the visualization of the rules obtained using graphic resources to enhance the analysis of the results in support of business decisions and contribute to mapping the users’ access profile. The proposal was validated by using data from user access to a digital news portal.

14
  • RAQUEL NUNES PEREIRA

  • Design of DGS Sensors for Monitoring Humidity in Civil Construction Materials

  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • FRANCISCO DE ASSIS BRITO FILHO
  • KLEBER CAVALCANTI CABRAL
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 20, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Humidity monitoring is essential in the construction industry to ensure the durability of materials and prevent structural problems. In this study, the analysis and development of planar structures using the defect ground structure (DGS) technique and two-port resonator, for sensing applications, are performed. The operating principle consists of varying the resonant frequencies of the studied elements when the relative permittivity of the material under test (MUT) is changed. The effectiveness of the sensor is proven through the analysis of materials with previously known dielectric constants that validate its applicability. In this project, its application is directed to the determination of the percentage of water present in two samples of dry sand and to the monitoring of water loss in three specimens made of mortar. The prototype was manufactured and the preliminary results obtained in the measurements were compared with the results of other works, certifying the effectiveness of the presented sensor.

Thesis
1
  • LUCILEIDE MEDEIROS DANTAS DA SILVA
  • Hardware Proposal of Evolutionary Algorithm for Outlier Detection in Streaming Applications

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • IGNACIO SANCHEZ GENDRIZ
  • LEONARDO ALVES DIAS
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • SERGIO NATAN SILVA
  • Data: Jan 12, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The amount of data in real-time, such as time series and streaming data, continues to grow. Analysing this data the moment it arrives can bring immense added value. However, it also requires much computational effort and new acceleration techniques. As a possible solution to this problem, we propose a hardware architecture for Typicality and Eccentricity Data Analytic (TEDA) algorithm implemented on Field Programmable Gate Arrays (FPGA) for data streaming. TEDA is based on a new approach to outlier detection in the data stream context. The suggested design has a full parallel input of N elements and a 3-stage pipelined architecture to reduce the critical path and thus optimise the throughput. To validate the proposals, results of the occupation, throughput and power efficiency of the proposed hardware are presented. Compared to other software platforms, the design reached a speed of up to 693x, with a throughput of up to 10.96 MSPs (Mega Sample Per second) with a dynamic power of 16mW. Besides, the bit-accurate simulation results are also presented for different application scenarios with multiple sensors ranging from applications in Industry 4.0 environments to the Internet of Medical Things (IoMT). This work is a pioneer in the hardware implementation of the TEDA technique in specialised hardware.

2
  • ELVIS MEDEIROS DE MELO
  • Learning Analytics and Online Evaluations: A Graph Data Science Methodology

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • BETANIA LEITE RAMALHO
  • DANIEL GOUVEIA COSTA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • RAYMUNDO CARLOS MACHADO FERREIRA FILHO
  • Data: Jan 24, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Evaluation plays an extremely important role as a systematic instrument for correcting failures and promoting successes in the learning process. It is one of the tripods of the students' schooling, along with the curriculum and the teaching and learning process. In view of the new reality with online education (e-learning) spread on a larger scale due to the Covid-19 pandemic, the Federal University of Rio Grande do Norte (UFRN) institutionalized the Multiprova platform to support online evaluation processes in the institution. With the computerization of evaluation processes, Learning Analytics (LA) challenges and the need to use new techniques, such as graph data science. Thus, the task of understanding how students behave, identifying student profiles, and gaining insights through online evaluation resolution records is a field of LA research that can be optimized with graph data science methodology. With the use of LA techniques such as Machine Learning (ML), there is a need to transform interpretable models in education. For this, data visualization and eXplainable Artificial Intelligence (XAI) techniques need to be considered. Based on this reality, the thesis hypothesis arises: Is it possible to use data from online evaluation resolution logs to obtain insights into the learning process and student profiles using LA techniques such as graph modeling and ML? To this end, the theoretical framework about the topics that make up the object of study is presented, such as graphs, LA and online evaluations. Among the results, a systematic literature review pointed to 40 papers involving LA and online evaluations, but no papers used graph metrics with LA techniques such as ML to analyze student performance. Thus, two case studies were modeled according to the proposed graph data science methodology. We realized the importance of using graph features in LA techniques in identifying insights about student learning considering their journey in online evaluation, as well as graph metrics and XAI for the interpretation of the results.

3
  • JONATHA REVOREDO LEITE DA FONSÊCA
  • APPLICATION OF ADAPTIVE PROTECTION IN CORRECTIVE SWITCHING FOR ELIMINATION OF OVERLOADS CONSIDERING PROTECTION RESTRICTION.

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • ARRHENIUS VINICIUS DA COSTA OLIVEIRA
  • JOSE JULIO DE ALMEIDA LINS LEITAO
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MELINDA CESIANARA SILVA DA CRUZ
  • RENATO MACHADO MONARO
  • Data: Feb 8, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The use of Corrective Switching technique to eliminate overloads in electrical systems, addressed in several studies in the last decades, has proved to be a very effective load flow control technique. Some of these studies are based on electrical circuit theories or Relief Function methodologies. Network switching causes changes to the system configuration and consequently the short-circuit levels of the buses are changed. These changes can lead to a network insecure operation when the protection parameters are not modified, since the overcurrent protection functions are based on the values of the rated currents and the short-circuit currents, which are previously defined in the protection studies. Adaptive Protection techniques makes it possible to recalculate the network protection parameters in real time, for any system configuration, enabling network operation with optimized protection settings. The purpose of this workis to implement the Corrective Switching technique, using, as a restriction condition in the choice of switching variants, the adjustments of the network protection parameters. If the network operation is not safe for the configuration proposed by the relief variants, new network protection parameters are calculated, as well as coordination and selectivity, is adopted and the Adaptative Protection technique is implemented. The network is automatically reconfigured through the Self Healing technique. 

4
  • DANIEL RODRIGUES DE LUNA
  • Adaptive Bandwidth Partitioning in 5G NR Systems Using Machine Learning Solution

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • ANDRÉ MENDES CAVALCANTE
  • MARCELO AUGUSTO COSTA FERNANDES
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • VICENTE ANGELO DE SOUSA JUNIOR
  • WALTER DA CRUZ FREITAS JÚNIOR
  • Data: Feb 13, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The fifth generation (5G NR) of the 3GPP communication network proposes a variety of use cases, ranging from improved mobile broadband communications (eMBB) to ultra-reliable low latency communications (URLLC), in addition to massive communications between machines (mMTC). Introducing flexibility in bandwidth utilization is one of the critical requirements of 5G technologies. As such, the concept of bandwidth parts is introduced to give flexibility, fast-changing configurations, and energy saving to UEs that do not need the whole bandwidth available by using just a part of it. The use case that can benefit from this feature is mMTC, characterized by its massive number of devices and the need for small power consumption. This work proposes a reinforcement learning solution of bandwidth part adaptation in mMTC scenarios to save energy and improve system statistics. Firstly, the subject and a complete section of related works with the more recent papers are introduced, highlighting the gap in this area of research. In addition, a brief theoretical approach to 5G is presented as part of the basis of this work. Then, the system model and main system parameters are described, along with the simulation tool used, the ns-3 NR 5G-LENA, in which calibration campaigns are carried out to validate its use. Afterward, we detail the investigation scenario in which we can apply the reinforcement learning (RL) solution. After decentralized and centralized solutions are proposed, new campaigns are created using both proposed RL-based bandwidth part adaptation solutions. The final results campaign shows the gains attained compared to a traditional fixed approach. Finally, the papers published and the main discussions of this thesis are gathered in the end.

5
  • RAFAEL LUCAS DA SILVA FRANCA
  • One-Terminal TravelingWave-Based Protection for HVAC and HVDC Transmission Lines

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • DIRK VAN HERTEM
  • FELIPE VIGOLVINO LOPES
  • FLAVIO BEZERRA COSTA
  • KAI STRUNZ
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • WASHINGTON LUIZ ARAUJO NEVES
  • Data: Feb 28, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This work proposes the development of one-terminal traveling wave-based transmission line
    protection methods for HVAC (High Voltage Alternating Current) and HVDC (High Voltage
    Direct Current) systems. The effect of the sampling frequency on the protection is considered,
    which until now has not yet been investigated for one-terminal methods. Inaccuracies on the
    wave velocity estimations, which classically yields to problems on methods based on traveling
    waves, are addressed and solutions to such problem are presented. The proposed methods have
    been evaluated by means of computer simulations. The proposed earth fault distance protection
    for HVAC transmission lines was evaluated using a real commercial relay with time domain
    based protection functions. The results related to the proposed earth fault distance protection
    for HVAC transmission lines show that the proposed function, when associated with other existing
    protection functions, can achieve a quite remarkable enhancement for the dependability and
    velocity of the transmission line protection. The results concerning the method based on traveling
    wave reflections show that it is possible to protect most point-to-point transmission lines in
    a fast way, without the need for communication, and independent of the estimation of the wave
    speed. Finally, the results concerning distance protection for meshed HVDC systems demonstrate
    the applicability of the proposed method for such systems. The method showed operating
    time below 2 ms for a line of 500 km length. This operation time meets the likely requirements
    that HVDC meshed systems will present. In addition, the method presented selectivity for a
    4-terminal system interconnected by 5 transmission lines.

6
  • JOSE WANDERSON OLIVEIRA SILVA
  • Improved Behavioral Box for Analysis of Tactile Discrimination Tasks in Rodents

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • ANDOUGLAS GONÇALVES DA SILVA JÚNIOR
  • BRUNO MARQUES FERREIRA DA SILVA
  • JULIO CESAR PAULINO DE MELO
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Mar 10, 2023


  • Show Abstract
  • Among the research works carried out with rodents in the area of Neuroscience, behavioral studies stand out. In order to carry out these studies, closed and controlled platforms are generally used in which the rodent is inserted, and tasks are elaborated, depending on the study, which the rodent must carry out. To study the learning of behaviors from tactile discrimination, for example, tasks are usually accompanied by a reward, normally following the reinforcement learning model. These platforms are commonly known as behavioral boxes. In this proposal, we aim to improve the methodologies and techniques used in this research area, developing new technologies for this type of study, including the automation of some procedures with the behavioral box aimed at tactile discrimination tasks. We did some initial tests of a behavioral box, using a computational model of physical simulation, from which we designed a new structure for the platform, with the best-elaborated spaces and materials, and using only components that can be bought in the market or easily developed. Our demonstrated hypothesis is that this new structure for the behavioral box improves the study of models related to the sensorimotor system in a more refined way. For example, the platform design enables more precise control of the opening of the discrimination bars, which is currently not done satisfactorily. The final model also allows for the design of more complex decision-making experiments using the camera and sensor system, allowing a better evaluation of rodent performance. This includes improvements in determining the number of correct answers in the tasks performed in the studies in question. Therefore, as a main practical contribution, we believe that the present study provides that laboratories that work with this type of research can enjoy a low-cost tool that is easy to develop. All material and documents developed are available on a multi-user collaborative platform.

7
  • DIEGO DA SILVA PEREIRA
  • Softwarized and Resilient Multi-UAV Network Applied to Rocket Impact Area Scanning

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • AUGUSTO JOSE VENANCIO NETO
  • CARLOS MANUEL DIAS VIEGAS
  • HELBER WAGNER DA SILVA
  • PABLO JAVIER ALSINA
  • TADEU FERREIRA OLIVEIRA
  • Data: Apr 14, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The scanning area procedure of the probable impact region is a mandatory step in the pre-launch 

    phase of any rocket. The objective is restrict the presence of unauthorized vessels, avoiding 

    possible accidents and, consequently, preserv human lives. Considering the high operational cost 

    of this procedure, normally performed by a P-95 aircraft, the SpaceVANT II project proposed the 

    execution of the area scan by a fleet of Unmanned Aerial Vehicles (UAVs) that, acting in a 

    cooperative way, have the ability to execute the mission with lower cost and operational complexity. 

    In this context, it is essential to create a communication network able to ensure the exchange of 

    information between the aircraft that make up the system. One of the most used alternatives to 

    provide this communication network is mobile ad hoc network (MANET) protocols adapted for 

    flying ad hoc networks (FANET). However, managing the dynamic behavior of this type of network 

    in order to minimize disconnections and enable the necessary conditions for the operation of 

    applications on board aircraft is not simple and has found limitations in the solutions adopted. In 

    this perspective, this thesis proposed a management based Software Defined Networking (SDN) 

    called SD-FANET. Design on a distributed and hierarchical architecture, the SD-FANET control 

    plane allows centralized management and assigns the controller the ability to program the 

    switches, changing the data forwarding from a holistic view of the network. The SDN approach 

    allows the use of different path selection algorithms, which adds more flexibility and improvement 

    to the forwarding process. To validate the proposed solution, experiments were carried out in the 

    emulated environment provided by Mininet-Wifi and a proof of concept based on a prototype using 

    a communication protocol developed to enable transmission of images in ZigBee communication 

    links embedded in DJI Phantom 3 Standard drones. The results showed that the throughput 

    obtained by SD-FANET was 22.2% better than MANET protocols and 5.4% in relation to the local 

    SDN controller. The average recovery time provides by resilience mechanisms was about 1.5 s.


8
  • SAMUEL BELARMINO DE PAIVA
  • Simulation and Design of MIMO Antennas for Applications in UWB, 5G and Smartphone Technologies

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALEXANDRE JEAN RENE SERRES
  • CUSTÓDIO JOSÉ DE OLIVEIRA PEIXEIRO
  • LAERCIO MARTINS DE MENDONCA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: May 23, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This work presents three MIMO (multiple-input multiple-output) antennas for applications in modern wireless communication systems. The first proposed MIMO antenna has compact dimensions, high isolation between ports and can be used for wireless local area network (WLAN) applications; the second proposed MIMO antenna is a miniaturized MIMO antenna, with high isolation between the ports and which can be used in ultra-wideband (UWB) applications; the proposed third MIMO antenna can be used for smartphone applications and covers the lower and upper WLAN bands, as well as 5G band. Among the advantages that 5G offers, we can highlight ultra-fast speeds, low latency, large channel capacity, high spectral efficiency and massive connection density. Then, MIMO antennas have been extensively studied for applications in this technology, because they can considerably increase the data rate and the channel capacity, due to the channel capacity being proportional to the number of antennas used in transmission and reception, as well they can also improve the link reliability of wireless communications systems through multi-path data transmission and reception. The proposed MIMO antennas were designed using ANSYS HFSS software for numerical characterization, and the prototypes were manufactured with FR-4 dielectric and measured, showing good agreement between simulated and measured results. A key performance parameter of MIMO antennas, the envelope correlation coefficient (ECC), is analyzed and presents good results for the three proposed MIMO antennas. Furthermore, for the proposed antenna for smartphone applications, the effects caused by the user's hands are investigated, which is an extremely important performance parameter.

9
  • JOÃO MARIA ARAÚJO DO NASCIMENTO
  • Diagnosis of Operating Conditions and Sensor Failures in Wells Operating by Mechanical Pumping Using Machime Learning

     
     
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • CARLA WILZA SOUZA DE PAULA MAITELLI
  • FABIO SOARES DE LIMA
  • OSCAR GABRIEL FILHO
  • RUTACIO DE OLIVEIRA COSTA
  • Data: Jun 16, 2023
    Ata de defesa assinada:


  • Show Abstract
  • In oil fields with many wells operating by Sucker-rod pumping, due to the lack of early diagnosis of operating conditions or sensor faults, several problems can go unnoticed. These problems can generate large losses, such as increased downtime, increased OPEX (Operational Expenditure), decreased efficiency and lost production. In practice, the identification and diagnosis of operating conditions are carried out from surface and downhole dynamometric cards, using pre-established standards, with human visual effort in the operation centers. This task requires a lot of time and work, in addition to requiring experience, as it can be influenced by subjective factors. However, in recent years, with the facilities inherent to Machine Learning (ML) algorithms, several researches on the subject have achieved good results in the diagnosis of operating conditions, showing that ML can be used for this purpose. However, it is still common to have doubts about the difficulty level of the dynamometer card classification task, the best algorithm, the best shape descriptor, the best metrics and what is the impact of the imbalanced datasets. In the search for answers to these questions, this work used real data from 38 wells operating by sucker-rod pumping in the region of Mossoró, RN, Brazil. More than 50,000 cards have been classified by specialists and distributed in eight modes of operation and two common sensor faults in this field. Sixty tests were performed and divided into seven groups. Three algorithms were tested (with and without hyperparameter tuning): Decision Tree, Random Forest and XgBoost, in addition to pipelines provided by Automated Machine Learning (AutoML). The descriptors used were: Fourier descriptors and Wavelet descriptors, in addition to the load values of the downhole dynamometric card. Balanced and imbalanced datasets were also tested. The results confirm the feasibility of applying ML for diagnosis of operating conditions and sensor faults in sucker-rod pumping systems, since 75% of the tests reached accuracy above 92% and a maximum accuracy was 99.84%.

     
     
10
  • JOSE KLEITON EWERTON DA COSTA MARTINS
  • A new method for design of nonlinear PID controllers under constraints using Fuzzy Takagi-Sugeno models

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • WALLACE MOREIRA BESSA
  • Data: Jun 26, 2023


  • Show Abstract
  • Most of the existing controllers in industries are from the PID family (Proportional-Integral-Derivative) developed for linear systems, although the processes are non-linear. Therefore, they present a significant loss of performance when operating outside the operating point for which they were designed. An alternative controller is the so-called PDC (Distributed Parallel Compensator) which, based on a Fuzzy Takagi-Sugeno model, results in a non-linear controller.

    The Fuzzy Takagi-Sugeno model is intrinsically non-linear, due to the membership functions that make up its structure. Thus, this model can represent nonlinear systems in such a way that, from the physical model of the system, it is possible to obtain a Fuzzy Takagi-Sugeno model that represents it exactly, which contributes to obtaining the PDC. The Fuzzy Takagi-Sugeno model can be represented by the composition of local models. In the PDC controller methodology, local controllers are designed, which can be a PID, for each local model, thus presenting the same rules structure as the Fuzzy Takagi-Sugeno model, that is, the controller shares the same membership functions.

    Normally, the PDC stability guarantee considers a quadratic Lyapunov function as a candidate, thus allowing it to be tested for linear matrix inequalities (LMIs) that are solvable using efficient convex optimization algorithms. However, polyhedral Lyapunov functions have shown advantages over the quadratic function, especially with regard to satisfying constraints on state, input and output variables, showing their potential to be used to guarantee stability and performance of a PDC-controlled system. In view of this, this work proposes an optimization-based method for tuning Proportional-Integral (PI) controllers for nonlinear systems subject to constraints on the controlled variable and actuator saturation. Conditions are presented for a polyhedron contained in the set of constraints to be invariant with respect to a closed-loop system with a controller subject to saturation. These conditions are used in the formulation of a bilinear programming problem whose solution provides the controller parameters that satisfy the constraints and an associated invariant set. Throughout the development of the work, several variations of the main technique were explored and their advantages and disadvantages were shown through the results.

    The results are presented in numerical examples. Starting with linear systems and testing I-P controllers and a traditional PI controller with a filter for the reference, we explore case studies with: saturation allowance, state constraints, time-delay, high order systems, servo and regulator problem. Then we explore nonlinear systems testing systems with and without the affine term and controllers with and without the feedfoward term, exploring case studies with: saturation permission, state constraints and servo problem. The results show that the developed method obtains a tuning for the controller that does not violate any state constraint and allows saturation, thus illustrating its efficiency.

11
  • MAGNO MEDEIROS DE ARAÚJO
  • The Design of a Glycerol Concentration Sensor Based on a Photonic Biosensor for Point-of-Care Application

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • IGUATEMI EDUARDO DA FONSECA
  • VITALY FÉLIX RODRÍGUEZ ESQUERRE
  • Data: Jul 27, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The manufacturing processes advancement in silicon wafers has enabled integration between electronics and photonics. Data will no longer be processed with electrons for the technology sectors but with photons, providing higher processing and transmission rates. In this context, the health and well-being sectors, for example, will have new equipment, allowing remote and individual monitoring and diagnosis, enhancing the prevention and treatment of diseases. Thus, this research proposes a photonic device with graphene applied and a surface plasmon resonance structure for sensing applications. Initially, they are concepts related to photonic devices and their different applications. Photonic crystals, plasmonic devices, graphene, and their use in optical guides are also presented. Then, the methodology used in the research development is explained, dealing with modeling and simulation. The results are presented and analyzed as the structure’s spectral behavior for different glycerol concentrations, which reinforces the potential for point-of-care applications considering its compactness and simplicity of construction.

12
  • FILIPE CAMPOS DE ALCANTARA LINS
  • DPO: Direct Planar Odometry with Stereo Camera
  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • VALDIR GRASSI JUNIOR
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ANDERSON ABNER DE SANTANA SOUZA
  • MARCELO BORGES NOGUEIRA
  • PABLO JAVIER ALSINA
  • Data: Jul 28, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Contemporary Visual Odometry (VO) methodologies generally are created upon point-based approaches to estimate the camera's pose and a representation of the environment explored. Direct Sparse Odometry (DSO) is the most popular point-based technique of a class of approaches called direct methods. Many works presented improvements in the point-based VO area using DSO characteristics as the fundamentals of these approaches. However, only recently, two new monocular plane-based DSO have been presented. The first approach utilizes a learning-based plane estimator to generate initial plane estimates, which may lead to optimization issues. The second approach restricts plane detection to horizontal and vertical orientations, making it more suitable for structured environments.

    This thesis presents a stereo plane-based VO technique - Direct Planar Odometry (DPO) - that employs planes as features in a Sliding window optimization framework and utilizes unit dual quaternion as the pose parameter. Our experiments show that the proposed methods achieved comparable results to the Stereo DSO point-based approach.

13
  • MICHEL SANTANA DE DEUS
  • PROGRAMMABLE PULSE INTEGRATOR AMPLIFIER FOR SYSTEMS ON CHIP

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • VALNER JOÃO BRUSAMARELLO
  • DIOMADSON RODRIGUES BELFORT
  • FERNANDO RANGEL DE SOUSA
  • RAIMUNDO CARLOS SILVÉRIO FREIRE
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Jul 28, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This work is an extension of previous studies and presents the research and development of a pulse width programmable gain integrating amplifier for chip systems. One of the main advantages of the proposed PGA architecture is that it uses few components and the number of gain values is independent of the circuit area. In addition, the architecture can be configured to operate with single-ended or differential signals.

     

    Before starting the Integrated Circuit (IC) development, equations defining the uncertainties of the circuit were obtained and a discrete circuit was designed, simulated, and developed, which went through a series of experiments to validate the proposed architecture.

     

    The implementation of the architecture in an IC aims to achieve higher operating frequencies, allowing its use in a wider range of applications. The integrated circuit was designed using the TSMC 0.18 µm CMOS technology, presenting an average power dissipation of 123.2 µW and occupying an area of approximately 0.065 mm2.

     

    Transient simulations were performed with and without noise, DC, AC, PSS, PAC, Corner, and Monte Carlo, evaluating means, uncertainties, relative and absolute errors related to various parameters. This suggests that the circuit was carefully designed and tested, and the presented results provide a solid basis for the application of the proposed PGA in a wide range of analog conditioning applications.

14
  • ÁLVARO PINTO FERNANDES DE NEGREIROS
  • High-level subsumption-based control architecture for sail-powered autonomous surface vehicles

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • EDUARDO CHARLES VASCONCELLOS
  • DAVI HENRIQUE DOS SANTOS
  • ESTEBAN WALTER GONZALEZ CLUA
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Aug 4, 2023
    Ata de defesa assinada:


  • Show Abstract
  • We propose a high-level control architecture for an Autonomous Surface Vessel (ASV) designed to overcome the challenges associated with executing missions under varying weather conditions and with energy autonomy. The project is built on the understanding that while a number of low-level control techniques are readily available as open source, there remains a need for a high-level control architecture. This architecture would facilitate the creation of a resilient, versatile sailing vessel capable of handling any mission without requiring the user to master navigation specifics, naval procedures, or corner cases. The proposed solution involves developing a control architecture inspired by subsumption, and centered on hierarchical behaviors. This structure incorporates a variety of specialized behaviors adapted to different contexts, each of which is established using reinforcement learning techniques (PPO). A combination of Gazebo simulation environment with the ROS framework for training was used to validate the proposed architecture. This simulation enables the digital replication of the vessel's behaviors, which simplifies the implementation process and mitigates the challenges and costs tied to real-world sailing operations. The results of this study indicate that the high-level control architecture of the virtual sailing vessel was successful in passing both perimeter scanning and long-distance tests. This suggests that the ASV is equipped to navigate the several situations it might encounter in real-world missions.

15
  • ISAAC DANTAS ISIDÓRIO
  • Observer-Based Output Feedback Control Using Invariant Polyhedral Sets for Fuzzy T-S Models Under Constraints

     

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • EUGENIO DE BONA CASTELAN NETO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • VILMA ALVES DE OLIVEIRA
  • Data: Aug 7, 2023


  • Show Abstract
  • In this work, a numerical method for the computation of observer-based output feedback controllers is proposed for fuzzy Takagi-Sugeno (T-S) systems subject to constraints, based on set-invariance theory. Positively Invariant (PI) polyhedral sets are used to ensure that state and control constraints are satisfied at all times. Sufficient conditions are established for a polyhedron defined in the augmented state space (state + estimation error) to be PI. From the invariance conditions, a bilinear optimization problem is formulated to simultaneously calculate the controller and observer gains and the positively invariant polyhedron that guarantee the satisfaction of the constraints. The two types of observers found in the literature of fuzzy T-S systems are considered: the first considers the membership functions dependent only on the system output, while the second refers to the general case, where these functions can be associated with any state variable. In the simplest case, although the membership functions depend only on the output, the estimated state feedback results, in general, in controllers with better performance and with larger sets of admissible states associated with them than the output static feedback control. For the general case, as membership functions depend on non-accessible states, an estimation mechanism is needed to calculate these variables. In both cases, this role is played by the fuzzy observer T-S. The problem of tracking a constant reference signal is also considered, for which the concept of robust positive invariance is used in conjunction with an Integral-Proportional (I-P) controller. Sufficient conditions are established for a polyhedron defined in the augmented state space (state + estimation error + tracking error integral) to be PI in the presence of a constant reference signal. Several numerical experiments illustrate the effectiveness of the proposed approach.

16
  • NELSON JOSÉ BONFIM DANTAS
  • Resonant and Antiresonant control of Multiple-Input Second-Order Systems with Time Delay using Receptance

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • FERNANDO DE OLIVEIRA SOUZA
  • JOSÉ MÁRIO ARAÚJO
  • PERICLES REZENDE BARROS
  • WALLACE MOREIRA BESSA
  • Data: Aug 22, 2023
    Ata de defesa assinada:


  • Show Abstract
  • A variety of problems in control engineering field deal with mathematical models under the form of systems of second-order differential equations, resulting from first-principles analysis using discretization (i.e., finite element method) to obtain finite-dimensional models. These models require, in general, an accurate knowledge of the parameters involved, such as, for example, masses, damping and stiffness coefficients in mechanical systems, for the design of controllers with high performance. The need to consider delays in measuring variables or actuation in these types of systems makes the problem more challenging, in view of the transcendent nature of the resulting transfer functions. In this context, the receptance concept emerges as an alternative, enabling the modeling of these systems entirely from experimental data, dispensing with the use of simplifying hypotheses and approximations, as is recurrently done in mathematical models with discrete parameters. Another virtue is highlighted in the waiver of approximations for the exponential term of the delay, which can result in undesirable solutions or very high order transfer functions. Since their introduction, receptance-based models have gained prominence in several works, with emphasis on the active control of vibrations by allocating zeros (anti-resonant frequency) and/or poles (resonant frequency). This work proposes a method for controlling second-order systems with multiple inputs and delays using receptance. The structure of the controllers uses state feedback, and the control objectives include partial placement of zeros and poles with guaranteed stability and robustness, based on the maximum peak of the sensitivity function. Stability is guaranteed from the extended concept of the Nyquist criterion for systems with multiple inputs. The synthesis of the controller is conducted from an optimization problem and the solutions are obtained using an algorithm based on evolutionary theory, where population evaluations are defined according to functions related to the frequency response of the systems. Numerical examples are presented to illustrate and discuss the performance of the solutions using the proposed method.

17
  • BRENO SANTANA SANTOS
  • A methodology oriented to unstructured data of scientific production for the temporal evaluation of research groups

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • RICARDO BARROS SAMPAIO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • JUAN MOISES MAURICIO VILLANUEVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Aug 29, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Funding agencies and research institutions often employ quantitative methods and scientometric techniques to evaluate scientific groups. These evaluations typically rely on a single type of metric, whether it is based on counts (such as the h-index) or derived from Complex Network Analysis. However, the use of multiple measurement approaches and the proper exploration of the temporal dimension of academic production is still a recurrent issue. Particularly, an underexplored approach involves combining these indicators with Machine Learning and Graph Embedding techniques, which could enhance the evaluation process of research groups. In this context, this study proposes a Graph Data Science-oriented methodology to analyze scientific teams over time. Through a case study, the results suggest the feasibility and suitability of the proposed method for quantitatively assessing research groups. The presented approach has the potential to provide strategic and proactive insights for scientific teams, contributing to a better understanding of their dynamics and limitations.

18
  • INGRIDY MARINA PIERRE BARBALHO
  • RevELA Platform: A digital health solution for the management of care and surveillance of patients with Amyotrophic Lateral Sclerosis in Brazil

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ANTONIO HIGOR FREIRE DE MORAIS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CRISTINE MARTINS GOMES DE GUSMÃO
  • DANILO ALVES PINTO NAGEM
  • JAILTON CARLOS DE PAIVA
  • KARILANY DANTAS COUTINHO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Aug 30, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Amyotrophic Lateral Sclerosis (ALS) is a rare neurodegenerative disease considered complex due to its heterogeneity. Despite being known for many years, few countries have accurate information about its epidemiology and the characteristics of individuals diagnosed with ALS, such as data related to the diagnosis and progression of the disease. In Brazil, the lack of information about ALS limits the use of data for advancing research and developing public policies that favor people affected by this health condition. In this sense, this work aims to present the development of a digital health solution for managing the care and monitoring of the ALS disease in Brazil to provide health surveillance with valuable and timely information to support the formulation of public policies and, at the same time, time to qualify and improve the follow-up of patients with ALS through an electronic health record. The proposed solution is composed of two tools: the Brazilian National Registry of ALS, responsible for collecting epidemiological data from patients with ALS throughout Brazil in a structured way; and the Electronic Health Record for ALS patients (PEP ELA, acronym in Portuguese), responsible for assisting in the multidisciplinary follow-up of patients with ALS, safely and adequately, based on the ALS Clinical Protocols and Therapeutic Guidelines (PCDT, acronym in Portuguese). This work was guided by the action-research methodology, and all phases of development of the platform were carried out sequentially in several cycles through the application of the iterative and incremental model using the SCRUM framework. It is essential to highlight that the development of this solution had the support of the Brazilian Ministry of Health and was conceived in response to the needs identified in the epidemiological scenario related to the disease, as well as the limitations reported by health professionals specialized in the care of patients with ALS. To promote security in the sharing of patient data, a blockchain network was modeled to receive smart contracts related to transactions carried out on the platform, thus ensuring the highest level of privacy and security. The developed platform has great potential for strengthening public policies since the data stored on the platform can be analyzed by teams of care specialists and public health managers, both in the individual and collective monitoring of people living with ALS in Brazil. The integration of surveillance and monitoring data can have significant benefits for the development of public policies and the planning of strategies at all levels of health care, in addition to providing a realistic view of the situation in the country about cases. Therefore, this digital health solution can be used for research, intervention, monitoring, and strengthening the response to ALS in the Brazilian Health System.

19
  • FELIPE RICARDO DOS SANTOS FERNANDES
  • DIGITAL HEALTH SOLUTION FOR ALTERNATIVE COMMUNICATION FOR PEOPLE WITH AMYOTROPHIC LATERAL SCLEROSIS

     

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ANTONIO HIGOR FREIRE DE MORAIS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CRISTINE MARTINS GOMES DE GUSMÃO
  • DANILO ALVES PINTO NAGEM
  • ERNANO ARRAIS JUNIOR
  • KARILANY DANTAS COUTINHO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Aug 31, 2023


  • Show Abstract
  • Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease that irreversibly impairs an individual's motor system and functional abilities, even causing the progressive loss of communication skills and autonomy. Technological resources based on Augmentative and Alternative Communication, Computer Vision, and Machine Learning are essential for developing digital health solutions to enable the communicative process and autonomy that, consequently, promote improvements in the quality of life and survival of people with ALS. Focused on a Human-Computer Interaction (HCI) approach based on images of the eyes from a simple camera not mounted on the body, this work presents an assistive technology resource for Augmentative and Alternative Communication for people with ALS. The approach proposed in this work consists of an algorithmic model capable of recognizing the state of the eye (open or closed) in real-time and interoperating with Autonomus, a digital health solution designed by the Laboratory of Technological Innovation in Health at the Federal University of Rio Grande do Norte (LAIS/UFRN) for the communication of people with ALS. The model consists of four methodological processes: (i) image acquisition; (ii) Face detection; (iii) eye detection; and (iv) classifying the state of the eye, which is the foremost step for Human-Computer Interaction. An algorithmic study with a control group was conducted to evaluate the model's overall performance and the Convolutional Neural Network (CNN) classification ability. The results related to the proposed model for classifying the state of the eye in real-time are promising and reach significant values of accuracy and f1-score above 92%. The results also point to the viability of developing low-cost assistive technology resources that guarantee universal access, health promotion, well-being, and reduced inequalities, which go beyond improvements in the communicative process of people with ALS. Therefore, the object of study of this work is also to enable and promotes the exercise of rights, citizenship, fundamental freedoms, and health care for people with ALS.



20
  • JOSÉ RAIMUNDO LIMA JÚNIOR
  • Two-Terminal Traveling-Wave-Based Non-Homogeneous Transmission-Line Protection

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FELIPE VIGOLVINO LOPES
  • FLAVIO BEZERRA COSTA
  • KLEBER MELO E SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • WASHINGTON ARAUJO NEVES
  • Data: Sep 4, 2023


  • Show Abstract
  • This work presents a two-terminal traveling-wave-based protection algorithm applied to non-homogeneous transmission lines comprising any number of sections with different topologies and considering the effect of the sampling rate. Existing two-terminal traveling wave protection functions cannot protect the line under close-in faults and present limitations in non-homogeneous transmission lines. However, the effects of the sampling rate, considered in the proposed method, result in well-defined protection and unprotected zones, essential for protection security and development of solutions to deal with the issue of close-in faults in non-homogeneous transmission lines. Furthermore, the algorithm can accurately detect the faulted section, allowing its use in advanced protection functions such as adaptive automatic auto-reclosing and high-speed protection schemes. A protection device was modeled considering a sampling frequency equal to 1 MHz, including functions to detect traveling waves via wavelet transform, and the proposed protection algorithm to discriminate line internal from external faults, and to select the faulted section. The algorithm was evaluated using a large number of Alternative Transients Program (ATP) fault simulations. The results show that the algorithm is robust and reliable for protection devices installed in non-homogeneous lines.

21
  • GABRIELA DE ARAUJO ALBUQUERQUE
  • Machine Learning Aplicado a Triagem de Osteoporose: modelo baseado em atenuação de ondas eletromagnéticas

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ANTONIO HIGOR FREIRE DE MORAIS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CRISTINE MARTINS GOMES DE GUSMÃO
  • GUILHERME MEDEIROS MACHADO
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • LORENA ITATI PETRELLA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Sep 21, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Osteoporosis is a silent and still underdiagnosed condition, with a mortality rate higher than several types of cancer, especially when patients suffer fractures. The gold standard equipment for the diagnosis of densitometry, Dual-energy X-ray absorptiometry (DXA, or DEXA), which requires an invasive and costly procedure, is scarce in countries considered middle or low-income, thus hindering timely access to diagnosis. In this context, a portable device, known in the literature as Osseus, was developed for the screening of patients who need the densitometry exam, i.e., to qualify the referrals of exams to the DEXA equipment. The thesis aimed to validate the Osseus device using machine learning techniques. For this, the planning and data collection of 505 patients who underwent the DEXA exam and the test on the Osseus device were carried out, of which 21.8% were healthy and 78.2% were diseased (they had low bone mineral density or osteoporosis). Therefore, to implement the studies and develop the research, the database was separated into 80% for training and validation (5-fold cross-validation) and 20% for testing. The performance obtained in the test base with the best model (Random Forest) corresponded to sensitivity=0.853, specificity=0.871, and F1(harmonic average of precision and recall rate)=0.859. The results showed that the most relevant variables to indicate the individual health status were age, body mass index (BMI), and the attenuation measured in the Osseus. When compared to the results of DEXA scans, the model has proven to be effective and consistent in screening individuals with osteoporosis and facilitating early diagnosis of the disease, which consequently entails improved productivity and reduced costs for surgery, treatment, and hospitalization. This way, by qualifying the referral of patients from primary care to the specialized network, the Osseus can improve the osteoporosis care network and consolidate itself as a resource of easy access in primary care, also impacting the reduction of waiting lines in the specialized network of the BrazilianNational Health System (SUS).


22
  • ANDRE HENRIQUE MATIAS PIRES
  • Fuzzy Controllers Optimization by Multiobjective Genetic Algorithms in the Wavelet Domain

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JEAN MARIO MOREIRA DE LIMA
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • MÁRCIO EMANUEL UGULINO DE ARAÚJO JÚNIOR
  • Data: Oct 2, 2023


  • Show Abstract
  • Due to the increasing competitiveness in the industry, it is imperative to use more efficient tuning techniques that can in fact find controllers with the desired performance. With this proposal, optimization techniques can be used to obtain the controller parameters according to an evaluation criterion, which should encode how good a particular controller is, properly expressing the desired specifications, so that the algorithm employed can find the controller. wanted. The methods traditionally used in tuning present the difficulty in expressing the desired specifications. The difficulty is due to the fact that the traditionally used criteria, in general, only use the total error information, through indices such as the Integral Absolute Error (IAE) or the Integral Square Error (ISE), which do not describe aspects of system behavior, such as if the response is very aggressive and oscillatory, steady state error, rise time and stabilization time, as a human designer would do. Some of these impressions are not well defined for references other than the step, lacking generality. Thus the optimization algorithm responsible for obtaining the controller parameters according to an evaluation function, which must actually be able to encode how good a given controller is, adequately expressing the desired specifications, so that the optimization algorithm employed can find the controller that best satisfies such a function. In view of this, a generic methodology for using wavelet analysis will be presented along with multiobjective optimization techniques to express more closely and closely related to the human behavior of the controlled system, allowing a more accurate optimization. In the proposed methodology, wavelet analysis, very present in the literature, focused on other applications, especially in the analysis of signals, sounds and images, is used to obtain descriptors that describe aspects of system behavior, such as its steady state behavior, behavior In the transient, no amplification of noise and rejection of disturbances, these descriptors become objectives that will be optimized by multiobjective techniques. The study carried out used Multiobjective Genetic Algorithm (MOGAs) techniques for optimization, due to their being widely used in the literature and known for their simplicity and efficiency.

23
  • MARIA GRACIELLY FERNANDES COUTINHO
  • Stacked Sparse Autoencoder applied to SARS-CoV-2 virus classification based on image representations of genome sequences

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIANA TAKAHASHI
  • ADRIAO DUARTE DORIA NETO
  • LEONARDO ALVES DIAS
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Oct 6, 2023


  • Show Abstract
  • Since December 2019, the COVID-19 pandemic caused by the SARS-CoV-2 virus has intensely affected the world. In the case of a novel virus identification, the early elucidation of taxonomic classification and origin of the virus genomic sequence is essential for strategic planning, containment, and treatments. Deep learning techniques have been successfully used in many viral classification problems associated with viral infection diagnosis, metagenomics, phylogenetics, and analysis. Considering that motivation, this work proposed an efficient viral genome classifier for SARS-CoV-2 using the deep neural network based on the stacked sparse autoencoder (SSAE). For the best performance of the model, we explored the utilization of image representations of the complete genome sequences as the SSAE input to provide a classification of the SARS-CoV-2. For that, two datasets were explored: based on k-mers image representation and based on CGR image representation. The dataset based on k-mers image representation was applied in the experiments of different levels of taxonomic classification of the SARS-CoV-2 virus, and the dataset based on CGR images was applied to the experiments of classification of SARS-CoV-2 variants of concern (VOC). For the experiments of taxonomy classification, the SSAE technique provided great performance results, achieving classification accuracy between 92% and 100% for the validation set and between 98.9% and 100% when the SARS-CoV-2 samples were applied for the test set. These results indicate that our model can be adapted to classify other emerging viruses. For the experiments of SARS-CoV-2 variants classification using CGR images, the SSAE technique provided even better results, achieving classification accuracy of 99.9% for the validation set and 99.8% for the test set. Finally, the results indicated the applicability of this deep learning technique in genome classification problems.

24
  • YURI PEDRO DOS SANTOS
  • Adaptive clustering of NOMA users in the power domain

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • TIAGO TAVARES LEITE BARROS
  • FABRÍCIO BRAGA SOARES DE CARVALHO
  • PEDRO THIAGO VALERIO DE SOUZA
  • Data: Oct 19, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The technique of Non-Orthogonal Multiple Access (NOMA, Non-Orthogonal Multiple Access) is intended to enable the transmission of two or more users sharing the same resources of time, frequency, and code, and thus significantly improve the spectral efficiency of wireless communication networks in future generations. Signal multiplexing can be achieved in the Power Domain NOMA (PD-NOMA), where superposed signals are transmitted with sufficiently different power levels. The efficiency of this method fundamentally depends on two previous processing steps: an adequate clustering of users (transmission candidates) with different channel gains and the choice of power levels that will be used to transmit each signal. The solutions presented in the literature to solve the user clustering problem do not consider the dynamics of the communication systems, that is, the temporal variation of the number of users and the channel conditions. To consider these dynamic characteristics when grouping users in NOMA systems, this work proposes a new clustering technique based on a modification of the evolutionary algorithm DenStream, chosen for its evolutionary capacity, robustness to noise, and online processing. Results show that the proposed clustering technique follows the system's dynamics, clustering all users and favoring the uniformity of the transmission rate between the clusters.

25
  • TARCIANA CABRAL DE BRITO GUERRA
  • Multi-Connectivity Solutions for LTE and NR Networks

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • FUAD MOUSSE ABINADER JUNIOR
  • LEONARDO AGUAYO
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • VALDEMIR PRAXEDES DA SILVA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • WALTER DA CRUZ FREITAS JÚNIOR
  • Data: Oct 27, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Dual connectivity (DC) technology (or, more generally, multiple connectivity (MC)) is an important feature in the initial journey of New Radio (NR), the access network of 3GPP to 5G, being the basis for the first ways of implementing this generation of communication systems. With MC, users can be simultaneously connected to legacy technologies (4G-LTE and Wi-Fi) and the new 5G-NR technology. However, such technology poses additional challenges for the network, especially with regard to energy management and the numerous connectivity configuration options. This work aims to conceive strategies based on machine learning capable of efficiently exploring the performance of MC towards 5G eMBB (enhanced Mobile Broadband) and 5G URLLC (Ultra Reliable Low Latency Communications) in heterogeneous networks. The idea is to dynamically configure the best set of MC parameters to provide increased data throughput (eMBB target) and a more robust connection (URLLC target), being relevant in scenarios with the presence of small cells using mmWaves, for example, both considered essential to meet 5G specifications.

26
  • ALCEMY GABRIEL VITOR SEVERINO
  • Representation Based on Stacked Autoenconder Optimized by Particle Swarm

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JEAN MARIO MOREIRA DE LIMA
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • SERGIO NATAN SILVA
  • Data: Nov 20, 2023


  • Show Abstract
  • Market competitiveness drives organizations to pursue technological development in order to improve product quality and reduce production costs while meeting the socio- environmental demands of consumers. However, industrial processes can pose challenges in real-time monitoring and control of critical variables. One solution to this problem is the use of soft sensors, which are algorithms capable of estimating difficult-to-measure variables based on easily measurable secondary variables. A common challenge in soft sensor projects is the lack of labeled data, making semi-supervised methods more promi- sing than traditional methods. In this context, the Stacked Autoencoder neural network architecture has been widely employed. This architecture is trained in an unsupervised manner and subsequently fine-tuned in a supervised manner. However, appropriately de- fining the hyperparameters of the Stacked Autoencoder, such as batch size, learning rate, and number of hidden features, presents a challenge. Traditional methods like Grid Se- arch and Random Search are computationally intensive and may not quickly find the best combination of hyperparameters. A more efficient alternative is the use of metaheu- ristic algorithms, such as Particle Swarm Optimization. These algorithms intelligently explore the search space and are more effective in high-dimensional spaces. A promising approach is to incorporate Mutual Information into the evaluation function of Particle Swarm Optimization, along with the Mean Squared Error. Mutual Information captures nonlinear relationships between the outputs of the Stacked Autoencoder and the actual system outputs, while the Mean Squared Error measures the difference between these outputs. In this context, the present thesis proposes the Representation Based on Particle Swarm Optimized Stacked AutoEncoder method, which utilizes Particle Swarm Optimi- zation with a modified evaluation function to optimize the hyperparameters of a Stacked Autoencoder-based soft sensor. It is expected that this approach will improve the accu- racy and representation capacity of the Stacked Autoencoder compared to conventional approaches that only utilize the Mean Squared Error. In order to evaluate the performance of the models generated by the proposed method, two widely used nonlinear processes in the industry were selected. These processes were chosen due to their relevance in virtual sensor implementation and are frequently employed in comparative analyses. The results demonstrate that the incorporation of Mutual Information in the evaluation function al- lows for a more efficient and balanced search, resulting in a Stacked Autoencoder with improved performance and representation capacity.

27
  • GLAUBER RODRIGUES LEITE
  • Uncalibrated visual servoing in the presence of non-gaussian feature tracking noise

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • JOÃO PAULO FERREIRA GUIMARÃES
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • PABLO JAVIER ALSINA
  • ÍCARO BEZERRA QUEIROZ DE ARAÚJO
  • Data: Dec 8, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Visual servoing is a control strategy that uses visual feedback from cameras to control the motion of a robot or a system. Image-based visual servoing relies on image processing and computer vision algorithms to detect and track image features, incorporating them directly in the control loop. That approach considers that there is a map, also known as interaction jacobian, between feature motion and camera pose based on the camera's intrinsic and extrinsic parameters. Although there are calibration techniques to compute the camera's parameters, they can become error-prone or need online changes, especially in unstructured scenarios. Some examples that could happen are when a task requires image zoom, the camera presents lens distortion, or its sensor has temperature sensitivity. Uncalibrated visual servoing studies aim to estimate the interaction jacobian using environment information and the measurement of features displacement, generally at run-time, with the help of an estimator, such as the Kalman filter. While most studies approximate the estimation uncertainty to a gaussian distribution, the environment in which the robot actuate could present more challenging characteristics. In that case, target occlusion, reflection, or similar appearance to other image objects can confuse the computer vision algorithm leading to outliers in the feature extraction. If not treated correctly, these errors may poor the performance of the visual servoing controller, or even affect its convergence. The maximum correntropy criterion can take advantage of the statistical properties of non-gaussian random variables. Thus, this work proposes a thesis theme study on dealing with non-gaussian feature tracking noise, preserving its statistical properties through the maximum correntropy criterion applied to the Kalman filter.
28
  • JOSE ILTON SARMENTO SILVEIRA JUNIOR
  • Reference Tracking via Output Feedback for Constrained Uncertain Linear Systems

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • JOSÉ MÁRIO ARAÚJO
  • TIAGO ALVES DE ALMEIDA
  • TITO LUÍS MAIA SANTOS
  • Data: Dec 8, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This thesis presents a robust output feedback control approach designed to address constant reference tracking in linear systems affected by uncertainties, disturbances, and measurement noise. Our research contributions revolve around three primary aspects. Firstly, we establish the conditions for achieving the Output Feedback Controlled Invariance (OFCI) property within the context of linear systems that incorporate polytopic uncertainties. This OFCI property guarantees robust constraint satisfaction through output feedback even in the presence of uncertainties. Secondly, we introduce a dynamic output feedback controller tailored to uncertain models, which employs set-membership observers. These observers effectively reduce the set of feasible states, enhancing tracking performance by minimizing errors. Thirdly, to further reduce tracking errors, we propose a model update procedure that adjusts the nominal model used for tracking based on output measurements. We conduct extensive numerical experiments to assess the controller's effectiveness, demonstrating its capability to achieve reference tracking with significantly reduced errors for the uncertain systems under consideration. Our research offers valuable insights into addressing constant reference tracking in linear systems with output feedback, constrained control and state, while accounting for uncertainties, disturbances, and noise. The potential applications of our approach hold promise for advancing control strategies in practical systems operating under uncertain conditions.

29
  • MÁRIO SÉRGIO FREITAS FERREIRA CAVALCANTE
  • Modified Type-2 Neuro-Fuzzy Structure for Identification and Behavior Prediction of Nonlinear Systems

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • THIAGO DE SOUZA ROCHA
  • ALLAN DE MEDEIROS MARTINS
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JEAN MARIO MOREIRA DE LIMA
  • ÍCARO BEZERRA QUEIROZ DE ARAÚJO
  • Data: Dec 11, 2023
    Ata de defesa assinada:


  • Show Abstract
  • System identification is a crucial sphere of engineering dedicated to finding econo- mical yet accurate models for fully understanding how systems behave. In effectuating this aim, these models predict future behavior while enabling simulations for optimization purposes inclusive of parameter adjustments where necessary for enhanced performance levels.

    However, what makes identifying systems challenging is the selection process regar- ding model structure choice and the estimation method used when making predictions concerning non-linearities present in complex phenomena affecting multiple variables. Nonetheless, experts have devised viable options toward precise modelling solutions by employing sophisticated techniques such as artificial intelligence algorithms or polyno- mial multi-model frameworks.

    he proposed thesis offers an approach that fuses interval type-2 fuzzy logic together with neural network training skills towards producing a generalized structure that enables both local model selection combined modeling which permits approximating or forecas- ting the behavior of any given system.

    The results were obtained using three case studies: the chaotic Mackey-Glass time equation, a furnace system, and a multisection tank system. The results of the pro- posed network for the approximation and prediction of these systems were compared with techniques from the literature, and the modified type-2 neuro-fuzzy interval network (MIT2FNN) showed lower mean squared error (MSE) values than the other techniques.

30
  • MYCHAEL JALES DUARTE
  • Analysis and Design of Ultraminiaturized FSS Structures for Applications in Temperature Sensing Systems
  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • LAERCIO MARTINS DE MENDONCA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 21, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This paper presents a study on ultra-miniaturized Frequency Selective Surfaces (FSS) for applications in temperature sensing systems. Two 2.5D FSS are proposed with elements inspired by convoluted metal lines printed on an FR-4 dielectric substrate. The inserted vias contribute to the capacitive and inductive effects in the structure, providing ultraminiaturization of the unit cell dimensions. The FSS have unit cell sizes equal to 4.68 % and 6.80 % of the wavelengths in free space for the frequencies of 2.34 GHz and 2.72 GHz (resonance frequencies), respectively, with the second structure exhibiting dual-band behavior. Two equivalent circuit models are proposed to better understand the operating principle of the FSS. The application of these structures for use in temperature sensing is studied. According to the literature, the electrical permittivity of the dielectric material used changes with the change in the material's temperature. With this in mind, simulations were carried out and the FSS showed a linear relationship between resonance frequency and temperature. The two proposed sensors were built and measured from room temperature up to 120 °C, and both showed excellent sensitivity to temperature changes. The numerical results simulated for the prototypes designed were obtained using the ANSYS HFSS software and the equivalent circuit model. The prototypes were built and the experimental characterization of the transmission coefficients, bandwidth and resonance frequency was carried out. The values obtained in the experiments were compared and discussed with the simulation results, which showed good agreement.

31
  • MARCOS TULIO ANTUNES BEZERRA SEGUNDO
  • The Application of Quasi-Periodic Sequence Models in Optical Waveguide

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • HUMBERTO DIONISIO DE ANDRADE
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • MAGNO MEDEIROS DE ARAÚJO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Dec 22, 2023


  • Show Abstract
  • In this work, waveguides based on directing light through media with sequentially refractive indices in the direction of propagation are proposed. The core guiding model of these structures is based on quasi-periodic sequencing of the refractive index that forms the signal propagation region. In this context, well-known optical fiber models are modified to adapt to the segmentation structures of optical signal guiding regions.

    These modifications enable the development of new optical device models, such as lasers, filters, and optical sensors. One of the most traditional segmentation models applied in optical waveguides is the Bragg Grating, also known as Fiber Bragg Grating (FBG), where the sequencing in the propagation region follows a periodic pattern. More recently, some quasi-periodic sequence models have been applied in photonic crystals, primarily considering the cross-sectional area of the waveguide. In this context, a new segmentation strategy is proposed, based on quasi-periodic sequencing of the refractive index along the direction of propagation.

    Structures of core fractionation in waveguides will be investigated by applying quasi-periodic models, such as Fibonacci sequences, Thue Morse, Period Doubling, and Octonacci, with the aim of comparing their performance with waveguides that use Bragg Grating as a segmentation strategy. For this study, a mathematical formulation based on the finite element method, in conjunction with the optical beam propagation method, will be used as a simulation tool. Parameters of transmission and reflection at the interfaces between the different media composing the applied sequences will be analyzed.

2022
Dissertations
1
  • MATHEUS NUNES ORSANO AIRES
  • A Wavelet-based Restricted Earth-fault Power Transformer Differential Protection

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • BRUCE A. MORK
  • RODRIGO PRADO DE MEDEIROS
  • WASHINGTON LUIZ ARAUJO NEVES
  • Data: Jan 20, 2022


  • Show Abstract
  • Power transformer differential protection schemes have been widely studied in recent years to improve their accuracy and speed. Researches have been developed by using the most varied digital signal processing techniques. Internal faults may cause critical damages to the power transformer, and they need special attention for this kind of disturbance, mainly in faults on the winding of the power transformer that is not too sensitive to the principal differential protections. This work aims to present a restricted earth fault protection based on the wavelet transform (REFW) for detecting ground faults close to the transformer neutral point (turn-to-ground faults) and supporting the conventional phase differential protection, which presents limitations in this kind of faults. The proposed REFW protection uses only high-frequency components instead of traditional low-frequency components obtained by means of phasor estimation methods, speeding up the detection of turn-to-ground faults.

2
  • LUCAS SOLANO CADENGUE
  • Intelligent Control of Omnidirectional Robots using Recurrent Neural Networks

  • Advisor : WALLACE MOREIRA BESSA
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ORIVALDO VIEIRA DE SANTANA JUNIOR
  • PHILIPPE EDUARDO DE MEDEIROS
  • WALLACE MOREIRA BESSA
  • Data: Mar 11, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Due to their great efficiency, security and flexibility, mobile robots are being increasingly used in industry. However, their positioning control is a great challenge due to the non-linear nature of this plant and the difficulty of estimating certain parameters, for example, the friction effects. In this work, non-linear controllers are applied to the trajectory control of an omnidirectional robot under the effect of unmodeled dynamics. The control approaches used in this work were both non-linear control strategies, Feedback Linearization (FBL) and Sliding Modes (SMC) both incorporated with an intelligent compensator utilizing Recurrent Neural Networks in order to assist the control by estimating uncertainties. The chosen architecture of the neural network was based in the need to compensate more complex dynamics and at the same time the restriction of computational complexity so that it could be embedded in the hardware of a mobile robot. The stability properties were proven by the principle of assintotic stability proposed by Lyapunov and the performance of the strategies were verifed through both simulations and experiments using Robotino, an omnidirectional mobile robot produced by Festo Didatics and a performance gain was observed when compared with the neural network without the recurrence.

3
  • REINALDO AGOSTINHO DE SOUZA FILHO
  • An OpenMP Implementation for the Nanvix Operating System

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • HENRIQUE COTA DE FREITAS
  • KAYO GONCALVES E SILVA
  • SAMUEL XAVIER DE SOUZA
  • TIAGO TAVARES LEITE BARROS
  • Data: Apr 26, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Multicore programming is not a trivial task. In some cases, multicore systems have no parallel programming interfaces, which requires operating system support to be made available. This work implements a version of the development interface of parallel programming Open Multi-Processing (OpenMP) for the Nanvix operating system. OpenMP is a parallel application development interface that allows for the intuitive abstraction of parallelism and the division of workload across processes. It is common to have memory limitations in platforms that embed codes in their projects. These memory limitations could make unavailable the use of an operating system with programming-friendly interfaces. The system software of embedded processing platforms is limited in programmability, requiring more knowledge from the programmer about the process and the hardware architecture used. The Nanvix is an operating system embedded in multicore platforms, being light enough to fit in memory restriction environments; however, it has standards that ease the programming. The Nanvix includes native parallel programming interfaces inspired on the Portable Operating System Interface (POSIX) adopted to implement some versions of OpenMP, that hopes to build an OpenMP version to the Nanvix it is going to result in easy coding for the operating system. In this work, the version of OpenMP uses Nanvix’s compilator to translate the compilation directives, and it assembles a library to the running routines. It was tested in an emulator of the RISC-V architecture. Some applications were built in the OpenMP version and their equivalent on the native Nanvix library of parallel programming to validate the library. The results show that, in some cases, OpenMP has more parallel efficiency compared to Nanvix’s native API, but in other cases, it has more performance. The programmability of Nanvix is improved with OpenMP, lowering the development time of parallel applications without a considerable performance loss, and in some cases, it is improving efficiency.

4
  • MÁRCIO LUIZ BEZERRA LOPES JÚNIOR
  • Stratification of Preterm Birth Risk in Brazil Through Unsupervised Learning Methods and Socioeconomic Data

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ALEXANDRE DIAS PORTO CHIAVEGATTO FILHO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LEONARDO ALVES DIAS
  • MARCELO AUGUSTO COSTA FERNANDES
  • RAQUEL DE MELO BARBOSA
  • Data: Apr 29, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Preterm birth (PTB) is a phenomenon that brings risks and challenges for the survival of the newborn child. Despite many advances in research, not all the causes of PTB are yet clear. It is currently understood that PTB risk is multi-factorial and may also be associated with socioeconomic factors. In order to analyse this possible relationship, this work seeks to stratify PTB risk in Brazil using only socioeconomic data, extracting and analysing those clusters that present relevant PTB divergence, all of which will be found by automatic clustering processes using a series of unsupervised machine learning methods. Through the use of datasets made publicly available by the Federal Government of Brazil, a new dataset was generated with municipality-level socioeconomic data and a PTB occurrence rate. This dataset was processed using two separate clustering methods, both built by assembling unsupervised learning techniques, such as $k$-means, principal component analysis (PCA), density-based spatial clustering of applications with noise (DBSCAN), self-organising maps (SOM) and hierarchical clustering. The methods discovered clusters of municipalities with both high levels and low levels of PTB occurrence. The clusters with high PTB were comprised mostly of municipalities with lower levels of education, worse quality of public services -- such as basic sanitation and garbage collection -- and a less white population. The regional distribution of the clusters was also observed, with clusters of high PTB located mostly in the North and Northeast regions of Brazil. The results indicate a positive influence of the quality of life and the offer of public services on the reduction of PTB risk.

5
  • PAULO RANNIER COSTA DA SILVA
  • Measurement of Oxygen Uptake Rate using Sigma Delta Modulator in the Biological Domain in Activated Sludge Systems

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • ANTONIO WALLACE ANTUNES SOARES
  • BRUNO AUGUSTO FERREIRA VITORINO
  • DIOMADSON RODRIGUES BELFORT
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: May 3, 2022
    Ata de defesa assinada:


  • Show Abstract
  • The activated sludge system is a wastewater treatment method, capable of removing water pollutants using aerobic bacteria metabolism. The oxygen uptake rate (OUR) is an important parameter to the evaluation and monitoring of the activated sludge system, since it allows evaluating the biodegradation of polluting organic matter. In this work,
    we propose a method to measure OUR based on the architecture of the first order sigma delta modulator in the biological domain. In this method, the operational functions of the sigma delta modulator will be performed by biological processes and electronic circuits. The proposed method has some advantages over existing OUR measurement methods. When compared to the classical method, it improves the dynamic response, decreases and
    fixes the sampling time; when compared to the PWM method, it introduces the benefits of noise modeling and oversampling. The performance of the proposed model is demonstrated through simulations.

6
  • ARTHUR DA COSTA FERNANDES
  • Real-time studies about the technique of Corrective Switching

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • ARRHENIUS VINICIUS DA COSTA OLIVEIRA
  • AYLANNA RAQUEL DA COSTA OLIVEIRA
  • EDNARDO PEREIRA DA ROCHA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Jul 26, 2022
    Ata de defesa assinada:


  • Show Abstract
  • With the growth of technologies for the automation of electrical systems, it is important to create ways to maintain the supply of electrical energy even in abnormal situations, with fast and low-cost resolutions, keeping load restriction as a last resort. The Corrective Switching technique is a tool capable of controlling the power flow of meshed networks by changing the network topology. The main advantage of this control methodology is that it does not involve additional costs, since its implementation depends on maneuvers by elements already present in the network. In previous works, several techniques and methodologies were developed to reduce the computational time needed to implement the technique, envisioning its application in the operation of systems in real-time. The present work aims to develop a computer program capable of identifying overloads in branches of the system and reconfiguring the network in real-time through the Corrective Switching technique. The simulations of electrical networks in real-time will be carried out through RTS. The computer program with the techniques and methodologies used to choose the switching variant will be developed using Scilab software, which will exchange information with the simulation in real-time in RTS. To improve the performance of the technique in the simulations, linearization techniques were also used to gain computational time. Finally, analysis of the results obtained from simulating the corrective switching technique in real time is presented.

7
  • EMANOEL LUCAS RODRIGUES COSTA
  • Self-Organizing Maps Applied to the Analysis of Atmospheric Pollutants

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • CRISTIANO HORA DE OLIVEIRA FONTES
  • MARCELO AUGUSTO COSTA FERNANDES
  • ÉDLER LINS DE ALBUQUERQUE
  • Data: Jul 27, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Air pollution is a problem that is increasingly present in our society due to the growing development of countries. In the study of air pollutants, multivariate statistical methods are commonly used, however, machine learning has proved to be a great alternative, presenting techniques capable of dealing with highly complex problems, such as air pollution. In this work, the machine learning technique, Self-Organizing Maps (SOM), was used to explore and analyze data on atmospheric pollutants and meteorological parameters from an air quality monitoring network, with stations located in the city of Salvador - Bahia. SOM offers several resources capable of making the study of data more comprehensive, which were used for the development of an individual and mutual analysis on the stations, being also briefly compared with a principal component analysis. From the visualization of the component planes, patterns between the air quality variables could be identified, as well as the observation of the present correlations, which were more specifically described by a hierarchical analysis of similarity, allowing to raise assumptions about their influence, formations and possible sources of emission, with a better description of the results. In addition, based on the arrangement of the neurons on the map, a study regarding data clusters could be carried out, enabling a balance on the samples and formation of clusters, characterizing in this way information related to the concentrations of pollutants, with their specificities and how they can be related to each monitoring station according to the division and arrangement of neurons.

8
  • LUISA CHRISTINA DE SOUZA
  • New proposal for viral genome representation applied to the classification of SARS-CoV-2 with deep learning

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • LUIZ MARCOS GARCIA GONCALVES
  • LEONARDO ALVES DIAS
  • Data: Aug 19, 2022
    Ata de defesa assinada:


  • Show Abstract
  • In December of 2019, the first case of COVID-19 was found in Wuhan, China, and in April of 2021, there were already 136 million confirmed cases. Due to the virus fast propagation, the scientific community has been making efforts to develop viral classifications techniques for the SARS-CoV-2. In this work, was developed, using a set of techniques from Genomic Signal Processing, a new proposal of genomic data representation of six viruses from the Coronaviridae family, which the SARS-CoV-2 belongs to. Then, the accomplished mapping was applied in a deep learning architecture for the samples' viral classification, obtaining accuracy of 94% e 91% for the sequences resized for the sizes of 64 and 128, respectively, also obtaining sensibility of 100% for the vectors with size 64. Lastly, given the mutation rate of the RNA virus, new variants emerged, and with them the possibility of an increase in cases. It was then, using the developed technique, carried out an analysis of the evolution of four variants of concern in three viral classification procedures, the results obtained aided comprehending the phylogenetic relationships between the variants.

9
  • KAROLAYNE SANTOS DE AZEVEDO
  • Deep Learning Applied to Classification and behavior analysis SARS-CoV-2 virus

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • SERGIO NATAN SILVA
  • Data: Aug 19, 2022
    Ata de defesa assinada:


  • Show Abstract
  • The new Beta Coronavirus, officially named SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus - 2 - SARS-CoV-2) is the virus causing COVID-19 disease. A member of the Coronaviridae family of viruses, SARS-CoV-2 is a positive-sense, single-stranded RNA enveloped virus that contains nearly 30,000 base-pair pairs - bp).RNA viruses tend to undergo more modifications than DNA viruses. Thus, when a virus is circulating widely in a population and causing many infections, the probability of its genome undergoing modifications increases, which may negatively affect some of its properties, becoming more transmissible and/or even more lethal. Within this context, this work proposes a tool, based on machine learning, which makes use of a deep one-dimensional (1D) convolutional neural network (CNN), intended for the classification and comparison of viral genomes of the new SARS-CoV - 2. As input, complete genomic cDNA samples (complementary DNA) were used, whose size varies between 26342 and 31029 base pairs (base-pair - bp) in length. Contrary to most approaches presented in the literature, the results obtained by this tool involving the classification of viruses, from the same family, reveal high values for the performance metrics, proving to be more reliable when compared to the works discussed in the state of the art. The proposed model was also used to verify possible changes in the genomic sequences of the main concern variants (alpha, beta, gamma), over a period of time, through their accuracy values, obtained through the classification between the variants.For this experiment, genomic samples from GISAID (Global Initiative on Sharing All Influenza Data - GISAID) were used, which also hosts epidemiological and clinical data referring to all variants related to SARS-CoV-2. The results obtained in this experiment indicate that the model can be used not only for classifying the virus of the Coronaviridae family, but also for predicting the behavior of SARS-CoV-2 variants over time.

10
  • ARTHUR ANDRADE BEZERRA
  • Indoor devices for automatic data collection of particulate matter in the air in the prevention of COVID-19 and other severe acute respiratory syndrome endemics

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDOUGLAS GONÇALVES DA SILVA JÚNIOR
  • DAVI HENRIQUE DOS SANTOS
  • JULIO CESAR PAULINO DE MELO
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Aug 26, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Este trabalho ou projeto de detecção de qualidade relevante, detectou e detectou ativamente um dispositivo de previsão de previsão e comparação com índices de dados de medição de previsão/final de qualidade com um microcontrole capaz de enviar como informações apresentadas para um banco de todos os dados. Por ser um projeto que necessita de grande escala para que seja possível capturar índices de qualidade do maior número de pontos possível para obter dados com uma granularidade muito alta, o desenvolvimento está sendo pensado semper visualizando o custo-benefício dos componentes para que replicar, e também o desenvolvimento faz parte de um projeto maior possível, que deve ser disponibilizado à comunidade uma plataforma completa, capaz de fornecer dados de qualidade do ar em tempo real.

11
  • FÁBIO HENRIQUE DE CARVALHO FERRAZ
  • An Optmization-Based MIMO PID Controller Tuning Method for Linear Systems Under Constraints

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • TIAGO ALVES DE ALMEIDA
  • Data: Oct 7, 2022
    Ata de defesa assinada:


  • Show Abstract
  • In this work we propose a methodbased on optimization for tuning PID controllers, for linear Multiple-Input Multiple-Output (MIMO) discrete-time systems subject to constraints on the output variables and saturation of the actuators. From a polytopic modeling of saturation, conditions are presented for a polyhedron contained in the set of constraints to be positively invariant with respect to a closed-loop system with a MIMO PID controller. Such conditions are used in the formulation of a nonlinear optimization problem, whose solution provides the controller parameters that satisfy the constraints, guarantee local stability and optimize the performance of the closed loop system. Both a centralized and a decentralized controller are analyzed. The efficiency of the proposed method is evaluated from numerical simulation results.

12
  • ALAN RODRIGUES DE SOUSA
  • Contributions to the Sliding Mode Control Strategy Applied to Grid-Forming Converters.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ALEXANDRE CUNHA OLIVEIRA
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Nov 9, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Distributed generation systems, which use renewable energy sources, are increasingly present
    due to the need to meet energy demand and environmental restrictions. Generally, such
    generation systems are connected to the electrical grid by means of power converters and,
    their integration into it, can produce instability in the electrical system. With the advancement
    in power electronics and the wide range of applications involving single-phase voltage
    converters, it is possible, with the appropriate control strategy, to dodge instability problems
    and also to offer improvements in power quality. For this, several control techniques have
    been studied for this purpose, however, the classical techniques fail for not having robustness
    to parametric uncertainties and are dependent on the system model. Thus, the control by
    sliding modes has gained space in the control of converters because it is a robust technique to
    parametric uncertainties and is independent of the system model, but the presence of
    chattering in the controlled variable in steady state is its main disadvantage. This master
    thesis presents a sliding mode control strategy applied to single-phase grid-forming converters.
    The proposed strategy employs linear systems analytical tools to determine the of closed-loop
    poles' suitable location when constrained to the splip surface. Furthermore, it is using a
    simplified structure for the internal current control. Simulation results obtained from a single-
    phase VSI connected to the grid operating under different operational conditions demonstrate
    the effectiveness of the proposed solution.

13
  • AMANDA KARINE MIRANDA DE OLIVEIRA

  • CHARACTERIZATION OF THE ATTENUATION OF RADIO FREQUENCY SIGNALS BY DIFFERENT MATERIALS USED IN CIVIL CONSTRUCTION

  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ERICA NATASCHE DE MEDEIROS GURGEL PINTO
  • FRED SIZENANDO ROSSITER PINHEIRO
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 27, 2022
    Ata de defesa assinada:


  • Show Abstract
  • In recent years, technological development and advances in the studies of communication systems based on radio-frequency (RF) have fostered several researches, with emphasis on the propagation of RF signals in the indoor environment. However, there is still an unfilled space with regard to research on the influence of construction materials on the propagation performance of these radio signals. This work aims to study the behavior of RF signals when reaching obstacles of building elements based on ceramic blocks, gypsum blocks and concrete blocks, and to experimentally determine the attenuation caused by these materials, which are currently most used in the construction civil. A measurement setup is proposed in this work and samples of these materials were subjected to RF signals in the frequency range between 700 MHz to 2500 MHz.They were analyzed in 03 samples of each type of material and the measured results for the attenuation of the signals were statistically treated and compared. The results indicate that the attenuation of the RF signal depends on the type of material used and its composition, therefore, it is necessary to develop studies in an attempt to propose new materials that meet the strength requirements demanded by civil construction and minimize the propagation losses of these signs in the indoor environment.

Thesis
1
  • BRUNO SÁTIRO DA SILVA
  • Equivalent Circuit Method Applied in Ring Geometries for Design of Selective Surfaces in Complementary Frequency

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • MAURICIO WEBER BENJÓ DA SILVA
  • Data: Feb 16, 2022


  • Show Abstract
  • The benefits of frequency-selective control of electromagnetic wave flow make frequency selective surface (FSS) a continuous subject of study in applied electromagnetism areas. With a wide range of applications in various engineering fields, FSS can be used, for example, as an antenna efficiency improvement tool, used for selective electromagnetic shielding, and even for fault detection in concrete structures such as bridge pillars. One particular class of FSS is the Complementary Frequency Selective Surface (CFSS) which has very interesting features together such as high angular stability, multiple transmission and/or reflection bands, and unit cell miniaturization. The analysis and design of this type of structure are commonly performed using commercial software that implements the so-called full-wave methods (FWM) which, despite having reliable responses, requires a license to use and demands high computational effort, impacting a longer time to obtain results. The Equivalent Circuit Model (ECM) provides approximate equations that, by calculating impedances related to unit cell geometry, model the behavior of frequency-selective surfaces in the frequency domain faster due to simplified formulas, which can be implemented in free software in many different programming languages, showing good agreement when compared to full-wave methods. This research aims to optimize the ECM when applied to complementary frequency selective surfaces formed by rings, uniting the interesting characteristics of both the cascade structure and the geometry. The study is paralleled with output techniques from transmission line theory and genetic algorithms for greater effectiveness of the method.

2
  • ELIZABETH VIVIANA CABRERA AVILA
  • Windowed Optimization for Stereo Visual Odometry Fusion

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • BRUNO MARQUES FERREIRA DA SILVA
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Feb 18, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Accurate motion estimation is an essential task accomplished in autonomous mobile agents' navigation (aerial or ground) and in robots navigation. In this thesis, we propose to reduce the error of stereo visual odometry when using 6 degrees of freedom poses through a graph optimization-based visual odometry fusion approach using the redundancy of captured information from the environment. Our approach uses two stereo images sets of a public dataset captured with a moving platform mounted on the top of a robot Pioneer 3AT to compute independent stereo odometry employing the LIBVISO algorithm and later fuse them. Our results are compared against two recognized SLAM frameworks ORB-SLAM2 and UCOSLAM and with the stereo odometry algorithm input. The relative pose error of the fused poses decreases by up to 94\% in relation to the error of stereo odometry and by up to 91\% compared with the results of UCOSLAM. Our implementations are open source and use public libraries.

3
  • ROSANA CIBELY BATISTA REGO
  • Lyapunov-based Intelligent Control

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ADEMAR GONÇALVES DA COSTA JÚNIOR
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • MARCUS VINICUS SILVÉRIO COSTA
  • TAKASHI YONEYAMA
  • Data: Feb 23, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Nonlinear dynamical systems play a crucial role in control systems because, in prac- tice, most of the plants are nonlinear. However, achieving control for nonlinear systems is not simple though many methods have been developed. There are still some problems to be solved, as robust control balance in humanoid robots and the modeling inaccuracies of the autonomous underwater vehicle, which has a small-pitch-angle. Usually, a Lyapunov function is used to perform a control and stability analysis of a nonlinear system. The procedure for obtaining a Lyapunov function is not a simple task. There have been many efforts and numerical methods in the literature on how to estimate Lyapunov functions for several kinds of systems. An artificial neural network is a useful tool for generat- ing functions. Motivated by this, we investigated the capability of a neural network to compute Lyapunov functions and provide a deep neural network to compute a control Lyapunov function without any linear approximation for nonlinear systems. Moreover, we examined the equilibrium point stability and obtained an estimation of its region of attraction contained in the set. Numerical examples and experimental simulations using some nonlinear systems, such as the inverted pendulum and the rotary inverted pendulum, are performed and compared with some conventional control techniques.

4
  • MARIA IZABEL DA SILVA GUERRA
  • Study of Intelligent Controllers for Tracking the Maximum Power Point of a Photovoltaic System

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • MARCELO ROBERTO BASTOS GUERRA VALE
  • Data: Apr 7, 2022


  • Show Abstract
  • Photovoltaic (PV) systems have shown growth in the world's electrical matrix. However, the non-linear nature of PV array and their strong dependence on ambient conditions decrease the maximum power they can produce and, consequently, reduce their performance and commercial attractiveness. Maximum Power Point Tracking (MPPT) techniques have been studied over the years to minimize these problems. Among the various control techniques used for spot tracking and maximum power, those that use intelligent algorithms to control the switching of DC-DC converters have shown a high potential for use. Therefore, the present work proposes to develop MPPT techniques based on Artificial Neural Network (ANN), fuzzy and Adaptive Neuro-Fuzzy Inference System (ANFIS) intelligent algorithms, to be applied to PV systems that have the buck-boost as a CC-CC converter. Three proposed architectures were developed for each algorithm. They were compared with each other and with the classic Perturb and Observe (P&O) algorithm. The proposals are distinguished by the input variables used, namely: irradiance and ambient temperature, for Proposal 1, with purely environmental parameters as input variables; irradiance and instantaneous output power of the PV array, for Proposal 2, with input variables that mixed environmental and electrical parameters; and instantaneous and previous instantaneous output power of the PV array, for Proposal 3, with purely electrical parameters as input variables. To assist in the study of the performance of the intelligent algorithms, two scenarios of PV systems, composed of PV array, buck-boost converter, MPPT and load, were modeled, identified Scenario 1 and Scenario 2. The scenarios were differentiated by the total power of the system. At the end of the analyses, it was noticed that the intelligent algorithms had a high tracking speed and were more stable than the P&O algorithms. The PV systems controlled by the intelligent algorithms of Proposal 1 showed the highest efficiency in reaching the maximum power point. The ANFIS and ANN algorithms were more prominent. In power generation, ANN recovered up to 12.05% of the energy lost when using P&O. In the Proposal 2 study, the PV systems also performed well, but lower than the Proposal 1 algorithms. The highest power generated was also achieved by the ANN. It generated 12.01% more power than the P&O. In Proposal 3, the intelligent algorithms had their efficiency compromised because the overlapping of some database values. Anyway, under Random condition, the intelligent algorithms still proved to be superior to P&O in tracking the maximum power point, recovering 8.27% of the generated power. Therefore, intelligent algorithms, especially ANN and ANFIS, have shown the relevance of their use in photovoltaic applications, especially in regions with random environmental conditions. Furthermore, the proposed intelligent algorithms are more attractive as the power of the PV system to be used is high.

5
  • VICTOR RAMON FRANÇA BEZERRA DE SOUZA
  • CONTRIBUTION FOR IMPROVEMENT OF LOW VOLTAGE RIDE THROUGH CAPABILITY ON DOUBLE FED INDUCTION GENERATOR WITH A BACK-TO-BACK MODULAR MULTILEVEL CONVERTER TOPOLOGY

  • Advisor : LUCIANO SALES BARROS
  • COMMITTEE MEMBERS :
  • KLEBER CARNEIRO DE OLIVEIRA
  • ANDRES ORTIZ SALAZAR
  • FLAVIO BEZERRA COSTA
  • FRANCISCO KLEBER DE ARAÚJO LIMA
  • LUCIANO SALES BARROS
  • Data: May 2, 2022
    Ata de defesa assinada:


  • Show Abstract
  • The advancements in power electronics have supported the widespread penetration of wind energy conversion systems (WECS) in electric grids. In this sense, the system based on the Double Fed Induction Generator (DFIG) has a large share of installed wind farms power generation technology, in this configuration the stator is directly connected to the grid and the rotor is interfaced by means of two back-to-back power converters, which have a crucial functionality in the machine control by means of voltages applied to the rotor terminals in order to ensure that the stator voltages and currents have the same frequency as the electrical grid, besides controlling the active and reactive power and are directly related to the harmonic distortion, thermal and mechanical stress levels in the WECS. Currently, several power converters topologies have been employed in order to improve the performance and increase the WECS processed power capability to support the network demand, in this sense, the multi-level converter topologies stand out and can be appropriately used to fulfill these requirements. On the other hand, one of the main features of the DFIG-based WECS is its high sensitivity to electrical disturbances, especially voltage sags, since the stator is directly connected to the grid, this feature highlights a fundamental challenge which is to provide fault support and in particular voltage sags to DFIG. Considering the relevance of this problem, this thesis presents a proposal focused on the improvement of DFIG supportability to a voltage sag in the grid by means of a recent multilevel converter topology, the Modular Multilevel Converter (MMC). The proposal is based on the use of the specific characteristics of the MMC through the presence of internal impedances, in order to provide significant damping of the DFIG transient components of the rotor and stator fault currents during a voltage sag in the grid, effectively contributing to maintaining the DFIG connection, while keeping the controllability and avoiding the protection activation, without the need of structural modifications or additional control loops. Moreover, the proposed structure using the MMC directly contributes to the improvement of the system performance by reducing the harmonic distortion rate and electromagnetic torque oscillation, reducing the heating and internal losses in DFIG windings and increasing the useful life of the gearbox, in addition to providing greater robustness, efficiency and reliability to the set of back-to-back power converters. Results obtained by means of simulations indicate the MMC effective damping capability of DFIG currents and the increase in supportability during a grid fault.

6
  • WERBET LUIZ ALMEIDA DA SILVA
  • Implementation of the Active Disturbance Rejection Control (ADRC) technique in the Radial Position Control of a Split-winding Bearingless Induction Machine.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • JOSSANA MARIA DE SOUZA FERREIRA
  • JOSE ALVARO DE PAIVA
  • JOSE ANDRES SANTISTEBAN LARREA
  • Data: May 19, 2022
    Ata de defesa assinada:


  • Show Abstract
  • This work aims to realize the rotor radial position control of a three-phase bearingless induction machine, with split-winding and optimized drive structure, using the Active Disturbance Rejection Control (ADRC) technique.  The development of vector control techniques, along with microcontrollers and power electronics components have increased the use of induction motors and turned it the most used machine topology in the world nowadays. Researches point that mechanical bearings are main cause of faults in electrical machines. Aiming to reduce maintenance, noise and vibration, many researches have been realized to develop and optimize bearingless machines structures. This special kind of machine has an operation strongly dependent on closed-loop control systems. As a system with multi-variable, non-linear, time varying and with coupled variables, it demands advanced control strategies to an efficient operation with a good dynamic performance. The ADRC controller considers the total disturbance (composed by non-modeled dynamics, non-linearity, uncertainty and changes in load) as a new system state, to be estimated in real-time throughout an extended state observer. On this way, these disturbances can be compensated in real-time, eliminating regime errors and with a suitable response to general disturbances. This technique will be applied as a position controller and the results will be compared with previous works for system operation with and without load applied to the machine shaft.

7
  • MARIANNE BATISTA DINIZ DA SILVA
  • A data stream-driven methodology for driver behavior modeling.

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • MAX MAURO DIAS SANTOS
  • EDUARDO ALMEIDA SOARES
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • JUAN MOISES MAURICIO VILLANUEVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: May 26, 2022


  • Show Abstract
  • The Internet of Things (IoT) is a growing network of objects — sensors, devices, systems, and more — that capture, transfer data, and communicate with each other through communication protocols. In addition, such objects have the ability to produce potentially unlimited sequences of data, called data streams. In this sense, it is clear that the IoT is creating new opportunities for various sectors, as can be seen in an unconventional way in the automotive sector. It is known that as a consequence of the advancement of architecture, vehicles are becoming increasingly equipped with various sensors and computational power. And, from available interfaces, it becomes possible to capture and extract, in an automated way, information through sensors and communication protocols present in vehicles and enabling a scenario known as the Internet of Intelligent Vehicles (IoIV). One of the benefits of IoIV is the creation of diagnostic applications, such as characterizing the behavior of drivers. This type of diagnosis is an essential requirement since the way you drive can impact different contexts, such as traffic safety, fuel consumption, emissions, and maintenance, among others. Furthermore, solutions generally available in the literature for analyzing drivers’ behavior focus on supervised offline learning models, fed with the entire dataset for training and testing. On the other hand, such solutions do not handle data streams suitable for online learning, that is, without knowledge of subsequent data. In face of this reality, the objective of this work is to identify patterns in the behavior of drivers, from a methodology oriented to data streams and unsupervised online algorithms. The methodology is adaptable and flexible, and considers the historical-temporal relationship between the samples, adapting in an autonomous and evolutionary way, without the need for a supervised training phase. In order to validate the proposed methodology, a case study was carried out in a real scenario with different conditions, which allowed the identification of daily driving operations. The results indicated the feasibility of the proposal regarding the identification of event detection and indicators of driver behavior. Therefore, the methodology can contribute to several applications, such as industry 4.0 — customized maintenance, fault detection — smart cities and urban mobility — improvement of pavements, increase in the number of speed reducers and crosswalks, decrease
    in the maximum speed of roads, among others.

8
  • MANOEL DO BONFIM LINS DE AQUINO
  • Circular Correntropy: Definition, properties and applications

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ALUISIO IGOR REGO FONTES
  • GUILHERME DE ALENCAR BARRETO
  • JOILSON BATISTA DE ALMEIDA REGO
  • JOÃO PAULO FERREIRA GUIMARÃES
  • Data: Jun 30, 2022


  • Show Abstract
  • Circular statistics has been applied to several areas of knowledge in which the input data is circular. Noisy measurements are still a problem in circular data applications and, like non-circular data, second-order statistics have some limitations to deal with non- Gaussian noise. Recently, a similarity function called correntropy has been successfully employed in applications involving impulsive noise for being capable of extracting more information than second-order methods. However, correntropy has not been studied from the perspective of circular data so far. This thesis defines a novel statistical measure called circular correntropy (CC). It uses the von Mises density function in order to redefine correntropy in this domain. In particular, it is proved analytically that the CC contains information regarding second-order and higher-order moments, being a generalization of the circular correlation measure. Its properties are studied as well as a new recursive solution for the Maximum Circular Correntropy Criterion (MCCC). The performance of this new similarity measure is evaluated as a cost function in nonlinear regression and time series prediction problems, where signals are contaminated with additive impulsive noise. Simulations demonstrate that CC is more robust than second-order circular statistics in impulsive noise environments.

9
  • MARCELLA ANDRADE DA ROCHA
  • Text Mining Applied to Analysis of Public Health Policy Interventions: the case of the Syphilis Epidemic in Brazil


  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CIPRIANO MAIA DE VASCONCELOS
  • DANIELE MONTENEGRO DA SILVA BARROS
  • MARQUIONY MARQUES DOS SANTOS
  • ANGELICA ESPINOSA BARBOSA MIRANDA
  • THAISA GOIS FARIAS DE MOURA SANTOS LIMA
  • ANTONIO HIGOR FREIRE DE MORAIS
  • Data: Jul 15, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Syphilis is a chronic infectious disease that remains a serious public health problem in much of the world. In Brazil, the rapid response to syphilis project, No Syphilis!, was created in 2018. This project has several strategies to combat syphilis, including the creation of a group of field researchers who worked in priority municipalities and produced thousands of text reports and added them to the platform. The objective of the work is to use the textual productions of the platform of field researchers of the No Syphilis project, LUES, for Text Mining to understand the impact of syphilis in the territory. The texts will be analyzed using some Data Mining (DM) algorithms. In addition, the answers from questionnaires from the "No Syphilis!" project will be used. with the purpose of finding relationships between the productions carried out and the questionnaires in the contribution of the reduction of syphilis. Associations of the data extracted from the questionnaires and reports with indicators of syphilis and its impact of the epidemic in the territory are tested. With this, it is possible to understand the most effective processes for reducing syphilis in the territories from the support strategy and the LUES platform.


10
  • JOSÉ JAIME GUIMARÃES PEIXOTO NETO
  • Frequency Selective Surfaces of the Type Absorb/Transmit Broadband

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • MAURICIO WEBER BENJÓ DA SILVA
  • Data: Jul 20, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Frequency Selective Surfaces (FSS) are increasingly being used in telecommunications systems due to the numerous advantages presented by this type of structure, among them the low cost, ease of fabrication and low profile. As well as frequency selective surfaces, electromagnetic wave absorbers have also been widely used, mainly with the objective of solving the problem of multiple paths. Absorbers are structures that aim to absorb electromagnetic waves in a certain frequency range, while allowing the passage of these waves outside it. Thus, this work proposes to investigate the use of FSS, for the design of multilayer absorbers, to obtain broadband absorption. The study consists of the application of resistive-type FSS combined with conductive-type FSS, which use square turns as unit cell geometry, to design an absorb/transmit structure with broadband-type frequency response. The proposed structure should operate in the frequency range between 2 GHz and 6 GHz. An extensive parametric analysis was performed to optimize the desired response. At the end of this analysis, two resistive and two conductive FSS were designed and cascaded to obtain the desired bandwidth. The analyzes showed that the broadband absorber has polarization independence and angular stability. The results obtained show that the absorber presents angular stability up to 30◦. Furthermore, experimental results show that the proposed structure can absorb signals in a frequency range from 2.4 to 6.13 GHz. Absorption above 80% occurs over the entire proposed frequency range. The structure can absorb signals for the entire ISM band (2.4 – 2.4835 GHz), 5G at 3.5 GHz and UNII (5 – 6 GHz), without blocking the other frequencies, avoiding multiple paths in the vicinity where the absorber it's installed.

11
  • VICTOR CARVALHO GALVÃO DE FREITAS
  • Velocity prediction of a pipeline inspection gauge (PIG) based on differential pressure and acceleration with artificial neural networks

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • GUSTAVO FERNANDES DE LIMA
  • JUAN MOISES MAURICIO VILLANUEVA
  • Data: Jul 28, 2022
    Ata de defesa assinada:


  • Show Abstract
  • In the oil and gas industry, a device known as the Pipeline Inspection Gauge (PIG) runs through oil and gas pipelines performing various maintenance operations. The efficiency of these operations can be increased by employing a closed loop speed control system. To get the speed, it is usually resorted to the use of odometers. Although such a method is relatively simple, it can cause certain measurement problems resulting from slippage between the odometer wheel and the duct. In order to contribute to the solution of these problems, the objective of this work is to develop a soft sensor (virtual sensor) to measure the velocity of PIGs from the pressure difference to which the device is submitted in the duct. A soft sensor is basically made up of two elements: a mathematical model of the system and sensors that measure the physical variables required by the model. To obtain the model, it is intended to use artificial neural networks. This model will be shipped in a Raspberry Pi to be installed in the PIG, which will also be responsible for obtaining the sensor data. The SIP testing pipeline from the Petroleum Assessment and Measurement Laboratory (LAMP / UFRN) will be used to evaluate the results. The proposed system is expected to be able to complement the use of odometers, thereby increasing the reliability of speed measurement.

12
  • JUAN RAFAEL FILGUEIRA GUERRA
  • Monitoring Relative Humidity in Concrete Blocks Using Frequency Selective Surface Sensor

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • FRED SIZENANDO ROSSITER PINHEIRO
  • GUTEMBERGUE SOARES DA SILVA
  • HUMBERTO DIONISIO DE ANDRADE
  • Data: Jul 28, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Due to the development of civil construction, there is a greater need for methods to indicate failures and damages of various kinds that may compromise the functionality of buildings. Within this aspect, the concept of Structural Health Monitoring (SHM) is used to define the use of technologies in order to establish assessments that enable the diagnosis of the conditions of a structure. There are technologies available for this purpose, such as optical, resistive and mechanical wave based sensors, however, they present difficulties regarding complexity and cost. Thus, the main objective of this work is to present a preliminary study of the use of Frequency Selective Surface (FSS) in the development of a transmission coefficient - based relative humidity sensor system, applied to concrete structures. Thus enabling a measurement in free space (noninvasive) and with less complexity than current methods. For this, it is necessary to understand the behavior of the electrical permittivity of the medium and the relationship between this and the resonant frequency of the FSS. Therefore, the electrical allowances of various materials used in civil construction were analyzed. Next, two distinct FSSs were designed and their frequency responses measured for various relative humidity levels of commercial concrete blocks. The results are in good agreement with the behavior discussed in the literature regarding central frequency displacement, and it is verified that it is possible to determine a direct correlation between the frequency variation and the relative humidity level for the chosen study object.

13
  • ALYSSON NASCIMENTO DE LUCENA
  • Micro-Brosh: Unmanned Micro-Aerial Vehicle with Low Operation Risk

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDOUGLAS GONÇALVES DA SILVA JÚNIOR
  • BRUNO MARQUES FERREIRA DA SILVA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • PAULO FERNANDO FERREIRA ROSA
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • Data: Aug 4, 2022
    Ata de defesa assinada:


  • Show Abstract
  • The risk involving the use of Unmanned Aerial Vehicles (UAV) has grown directly with its popularization. It is a global concern of regulatory agencies to reduce these risks. In Brazil the National Civil Aviation Agency (ANAC) waives most requirements for UAVs up to 0.250 kg. In this perspective, the present study aims to propose the design and development of a micro UAV flying wing model with remote or autonomous piloting capability with low risk of collision with people and facilities (Micro-Brosh). With a maximum wingspan of 0.30 m and a final weight of 0.160 Kg, the Micro-Brosh UAV's main feature is its easy and safe operation, being able to be launched manually and with the realization of landing on grass cover, without causing damage to the aircraft. We introduce the proposed architectural design, with aerodynamic and performance analyses, demonstrating parameters such as lift, thrust, drag, stall speed, and flight time. In our tests, the prototype proved to be superior to almost all other UAVs in the literature studied, except for one that has similar size and flight time characteristics, but with greater weight and size than the Micro-Brosh. In all, 6 prototypes were built and analyzed in more detail, resulting in the final model that was validated through flight tests and bench tests. In addition to the safety advantages, another important aspect is that the costs associated with the construction and maintenance of the Micro-Brosh is below US$ 500, a value considered low in relation to the traditional UAVs surveyed.

     

    O risco envolvendo o uso de Veículos Aéreos não Tripulados (UAV) tem crescido diretamente com a sua popularização. É uma preocupação mundial das agências reguladoras diminuir esses riscos. No Brasil a Agência Nacional de Aviação Civil (ANAC) dispensa a maioria das exigências para UAVs com até 0,250 Kg. Nesta perspectiva, o presente estudo tem como objetivo propor o projeto e desenvolvimento de um micro UAV modelo asa voadora com capacidade de pilotagem remota ou autônoma de baixo risco de colisão às pessoas e instalações (Micro-Brosh). Com uma envergadura máxima de 0,30 m e peso final de 0,160 Kg, o UAV Micro-Brosh tem como principal característica a operação fácil e segura, podendo ser lançado manualmente e com a realização do pouso em capo gramado, sem causar danos à aeronave. Introduzimos o projeto arquitetônico proposto, com análises aerodinâmica e de desempenho, demonstrando parâmetros como sustentação, empuxo, arrasto, velocidade de estol e tempo de voo. Em nossos testes, o protótipo demonstrou ser superior a quase todos os outros UAV da literatura estudados, menos um que possui características de tamanho e tempo de voo similars, porém com peso e tamanho maiores que o Micro-Brosh. Ao todo, foram construídos e analisados mais detalhadamente 6 protótipos, resultando no modelo final que foi validado através de testes de voo e testes de bancada. Além das vantagens de segurança, outro aspecto importante é que os custos associados com a construção e manutenção do Micro-Brosh fica abaixo de \$500, um valor considerando baixo em relação aos UAVs tradicionais pesquisados.

     
14
  • THALES QUEIROZ FONSECA
  • Virtual Impedance-Based Control Strategies for Voltage Supporting in LCL-VSC Converters

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FLAVIO BEZERRA COSTA
  • ANTONIO MARCUS NOGUEIRA LIMA
  • JOSEP MARIA GUERRERO ZAPATA
  • MAURICIO AREDES
  • Data: Aug 5, 2022


  • Show Abstract
  • The advances in power electronics and environment restrictions have driven the insertion, as distributed generators (DG), of renewable energy based systems on the power grid, the main one being those who use the photovoltaic and wind systems as primary energy sources. The interconnection of these sources with the power grid is generally obtainedbyVSCconvertersandLCorLCLfilters,beingcalledasLC-VSCorLCL-VSC systems. Such systems are highly variable in power generation, which may cause voltage fluctuation and frequency deviation in the electric grid. LC-VSC systems are controlled to operate as a controlled voltage source connected to the grid and they can regulate the amplitude and frequency of the voltage of the point of common coupling (PCC). LCLVSC are controlled to operate as controlled current source connected to the grid and they are still the most common system employed currently. Therefore, in this doctoral qualification, are proposed virtual impedance-based control strategies applied in LCL-VSC systemsforPCCvoltageregulation. Thevirtualimpedanceisusedforshapingtheequivalent DG system impedance connected to the grid and regulate the power flow of these systems for achieving the required PCC voltage regulatio

15
  • ANAMARIA SENA MAIA
  • Design of dual band microwave absorbers using frequency selective surfaces

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • MAURICIO WEBER BENJÓ DA SILVA
  • Data: Nov 8, 2022


  • Show Abstract
  • Currently designs developed in wireless network systems are on signal confinement. We observe the need to increase security and restriction of services, in which electromagnetic signals must remain only in a specific room, without external transmittance. Consequently, several researches are studying the use of Frequency Selective Surfaces (FSS) as a way to reduction electromagnetic interference (EMI) and to maintain the systems' compliance. With characteristic and distinct performance of the conventional passive absorbers of Salisbury and Jaumann, that present good absorption in the band of stop, but, low transmission in the external bands. The absorbers with FSS propose to act with transparency to the electromagnetic waves of the incident plane in the passing band, while absorbing the waves in the wanted frequency bands. Therefore, the objective of this work is to design a microwave absorber structure integrated with frequency selective surfaces with multiband performance. Studies described in the literature are analyzed to obtain such desired absorption characteristics, later structures are projected with variation of their respective parameters. Demonstrating mastery in the use of the commercial software used in the simulations, and understanding the effects of the parametric variations of the devices examined.

16
  • VERIVAN SANTOS LIMA
  • Thermal profiles in water injection wells: reduction of the systematic error in the flow measurement during the
    transitional regime.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • CARLA WILZA SOUZA DE PAULA MAITELLI
  • DIEGO ANTONIO DE MOURA FONSECA
  • GUSTAVO FERNANDES DE LIMA
  • WERBET LUIZ ALMEIDA DA SILVA
  • Data: Dec 12, 2022


  • Show Abstract
  • This work is a contribution to flow measurement techniques in water injection wells in oil
    production fields, focusing on the first moments of the operation. The technique developed by
    Ramey (RAMEY JR et al., 1962) was chosen, which, although it is aimed at calculating the
    temperature in the injection fluid, it has been adapted to calculate the flow. In this technique,
    the calculation is based on the relationship between the heat flow established in the well and the
    temperature difference between the injection fluid and the geothermal temperature, naturally
    established in the reservoir. Due to the mathematical complexity involved in the heat and mass
    transfer mechanisms, many simplifications were adopted in the development of the theory, limiting its application in the first moments of the operating cycle. In the considered times, the
    neglect of heat transfer in completion constitutes the main source of systematic error inherent to
    Ramey’s methodology. With lesser intensity, but still significant, the failure to observe the temporal variation of the injection fluid also results in a systematic error that needs to be addressed.
    The reduction of the systematic errors listed is the main product of this thesis.


17
  • RUANN VÍCTOR DE ANDRADE LIRA
  • Elliptical UHF Sensor for Partial Discharge Detection

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALEXANDRE JEAN RENE SERRES
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • LAERCIO MARTINS DE MENDONCA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 15, 2022


  • Show Abstract
  • In this work, simplified geometries for microstrip antennas were evaluated and optimized, to select one appropriate geometry, aiming for its application of partial discharge (PD) detection, as a UHF sensor. To improve the performance of the proposed antenna, cascaded frequency selective surfaces (FSS), using double square loops as a unit cell element, were designed and evaluated. Antenna reflection coefficient measurements without and with the integrated FSS were performed and compared with simulated results. The results show that the insertion of the FSSs did not impact the operational bandwidth of the antenna, which comprises 100$\%$ of the characteristic frequency range, of the PD activity (300 – 1500 MHz). The insertion of the FSSs resulted in an average gain of 4 dBi, concerning the isolated antenna, increasing the sensitivity for PD detection, within the proposed frequency range. We evaluated the PD detection of the structure through measurements in three devices, a bar of a hydro generator, an oil tank with electrodes in the flat-tip configuration, and a potential transformer (PT). The proposed UHF sensor for PD detection could detect PD activity in all three scenarios and for levels lower than 10 mV. 

18
  • EVANDSON CLAUDE SEABRA DANTAS
  • ELECTRICAL EQUIVALENCE PYRANOMETER WITH AMBIENT TEMPERATURE ANALOG COMPENSATION

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • ANTONIO WALLACE ANTUNES SOARES
  • DIOMADSON RODRIGUES BELFORT
  • FERNANDO RANGEL DE SOUSA
  • RAIMUNDO CARLOS SILVÉRIO FREIRE
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Dec 20, 2022


  • Show Abstract
  • Pyranometers are devices used to measure incident radiation per unit area. This type of device is found in many applications in the field of solar energy, UV treatment, atmospheric research, etc. Some of these devices are based on the principle of electrical equivalence, in which radiant power is equated with electrical power in a thermoelectric balance. The balance of this balance usually occurs by compensating the radiant power by an electrical power to maintain a resistance thermometer at constant temperature. This configuration, however, has limitations when the ambient temperature varies, varying parameters such as sensitivity, useful output voltage, power consumption, among others. In this work, it is proposed to replace the configuration that keeps the sensor temperature constant for the configuration of constant temperature difference. The proposal is formulated by modifying the architecture of the feedback Wheatstone bridge so that it works with a constant temperature difference. The implemented
    proposal is then validated through computer simulations in a SPICE environment and through field experiments. In this work, a prototype was developed that was tested in 3 different climatic conditions, namely: clear weather, partially cloudy weather and cloudy wheater. Results of this work point to an improvement in the useful voltage range by 5 times, a reduction in the influence of ambient temperature variation on the output voltage, a reduction in electrical consumption and an increase in the sensitivity to incident radiation.

2021
Dissertations
1
  • MAILSON RIBEIRO SANTOS
  • A Methodology Based on Evolving Systems for Fault Detection and Identification of Dynamic Systems

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • CLAUBER GOMES BEZERRA
  • Data: Jan 7, 2021


  • Show Abstract
  • This work proposes a methodology for the detection and identification of failures in dynamic systems, through an online and evolutionary approach. The proposal is divided into three stages, in which data pre-processing and post-processing are carried out to increase the robustness of the methodology in the presence of outliers and noise, in the pre-processing the selection of characteristics, normalization is carried out of data, filtering and adding regressors, in post-processing time filtering is performed. In the processing stage, an adaptive and unsupervised approach is applied, through the Auto-Cloud algorithm, which performs grouping and classification of data streams. To validate this proposal, different evaluation metrics were used, such as Adjusted Rand Index (ARI), homogeneity, completeness, precision, f1_score, recall, and satisfactory results were obtained. Finally, the conclusion of this work is presented, in addition to proposals for future work.

2
  • VINÍCIUS SOUSA DE OLIVEIRA
  • Study and application of cryptographic algorithms for wireless sensor networks in a software-defined radio environment

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • DIEGO ANTONIO DE MOURA FONSECA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RODRIGO SOARES SEMENTE
  • Data: Jan 29, 2021


  • Show Abstract
  • In this work is proposed a comparative study of cryptographic algorithms to be applied in Wireless Sensor Networks. Having as motivation the lack of researches with practical results, the main goal of this work is to verify the viability of the insertion of studied algorithms in a real environment based on a Software-Defined Radio system. Due to the internal limitations of each node, efficiency is an aspect as important as cryptographic quality, in order to ensure a good performance of the security technique. For this, it will be analyzed data such as execution time, memory usage, processing cost and power consumption. Thereby, it is expected to increase the security in Wireless Sensor Networks, having in consideration its performance, memory and energy constraints.

3
  • FELIPE FERNANDES LOPES
  • Fully parallel implementation of an SVM with SGD-based training on FPGA

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • MARCELO AUGUSTO COSTA FERNANDES
  • ORIVALDO VIEIRA DE SANTANA JUNIOR
  • VICENTE IDALBERTO BECERRA SABLON
  • Data: Jan 29, 2021


  • Show Abstract
  • Artificial intelligence, machine learning, and deep learning have proven to be powerful techniques for solving natural language processing problems, computer vision, and others. However, its computational and statistical performance depends on other factors of the algorithms used for training, the computing platform used, and even the numerical precision used to represent the data. One of the main machine learning algorithms is the Support Vector Machine (SVM), most commonly trained through minimal sequential optimization, contributing to low computational performance. As an alternative, algorithms based on Stochastic Gradient Descent (SGD) have better scalability and can be used as good options for training machine learning algorithms. However, even with algorithms based on the stochastic gradient, the training and inference times can become long depending on the computing platform employed. Thus, accelerators based on Field Programmable Gate Arrays (FPGAs) can be used to improve performance in terms of processing speed. This work proposes a fully parallel FPGA implementation of an SVM with SGD-based training. Results associated with hardware occupation, processing speed (or throughput), and accuracy for training and inference in various quantization formats are presented.

4
  • ANDRESSA STÉFANY SILVA DE OLIVEIRA
  • Macro SOStream: An evolving algorithm to self organizing density-based clustering

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • DANIEL FURTADO LEITE
  • DANIEL ALOISE
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Mar 19, 2021


  • Show Abstract
  • Situations that generate a continuous data stream, such as TCP / IP traffic, e-commerce, and industrial monitoring, can make the usability of algorithms that have machine learning completely offline unviable. That is due to the need for data storage, the infinite growth of data generation, and limited memory restrictions. With that, the algorithms that have the learning totally or partially on-line appeared. Among them, there are the evolving algorithms, which have been of interest because they can develop and update in unknown environments and detect concepts drift and evolution in the input data over time. Because of these algorithms' broad applicability in real problems, this work proposes a new evolving algorithm named Macro SOStream. This algorithm has on-line learning and is based on self-organizing density for data stream clustering. The Macro SOStream is based on the SOStream algorithm, but we incorporated macroclusters composed of the microclusters. While microclusters have spherical shapes, macroclusters can have arbitrary shapes. Besides, the Macro SOStream's performance was compared to SOStream and DenStream algorithms' performance using the datasets and the ARI performance metric to validate our proposal.
5
  • VÍTOR SARAIVA RAMOS
  • Real-Time Highlight Removal from a Single Image

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • LUIZ GONZAGA DE QUEIROZ SILVEIRA JUNIOR
  • RAFAEL BESERRA GOMES
  • FRANCISCO MADEIRO BERNARDINO JUNIOR
  • Data: Mar 31, 2021


  • Show Abstract
  • The problem of highlight removal from image data refers to an open problem in computer vision concerning the estimation of specular reflection components and the removal thereof. In recent applications, highlight removal methods have been employed for the reproduction of specular highlights on high dynamic range (HDR) displays; to increase glossiness of images in specular reflection control technologies; to improve image quality in display systems such as TVs; and to enhance the dynamic range of low dynamic range (LDR) images. However, the underlying processing required by state-of-the-art methods is computationally expensive and does not meet real-time operational requirements in image processing pipelines found in consumer electronics applications. In addition, these applications may require that methods work with a single frame in imaging or video streams. Consequently, this work has the objective of proposing a novel method for the real-time removal of specular highlights from a single image. The essence of the proposed method consists in matching the histogram of the luminance component of a pseudo-specular-free representation using as reference the luminance component of the input image. The operations performed by the proposed method have, at most, linear time complexity. In experimental evaluations, the proposed method is capable of matching or improving upon state-of-the-art results on the task of diffuse reflection component estimation from a single image, while being 5X faster than the method with the best computational time and 1500X faster than the method with the best results. The proposed method has high industrial applicability, and targeted use cases can take advantage of contributions of this work by incorporating the proposed method as a building block in image processing pipelines.

6
  • VICTOR RAMON FIRMO MOREIRA
  • Intelligent control of an omnidirectional mobile robot with reinforcement learning for decision making

  • Advisor : WALLACE MOREIRA BESSA
  • COMMITTEE MEMBERS :
  • WALLACE MOREIRA BESSA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ORIVALDO VIEIRA DE SANTANA JUNIOR
  • ESTHER LUNA COLOMBINI
  • Data: Apr 12, 2021


  • Show Abstract
  • The evolution of robotic systems has become evident over time. Due to the advances in mechanical manufacturing and the new algorithms used, mobile robots have become increasingly independent in their actions. Regarding machine learning strategies, special attention is given to reinforcement learning algorithms, because of its similarities with the biological learning process. This work proposes the development of an autonomous agent, combining intelligent control strategies with decision-making algorithms. For the implementation of the proposed strategy, the Robotino omnidirectional mobile robot will be used. Simulations of the robot's performance were performed to explore space in an environment, for which a specific mathematical model is applied. For system control, the Linearization by Feedback strategy was combined with a compensator based on Artificial Neural Networks to deal with uncertainties and possible external disturbances. The epsilon greedy algorithm, in turn, was chosen to enable the robot in the decision-making process. The results show that the intelligent control strategy was efficient and the proposed intelligent agent was able to explore the environment effectively, obtaining a high average reward. The perspective is that the strategy is still implemented experimentally in Robotino.

7
  • ERIKA AKEMI YANAGUIBASHI ALBUQUERQUE
  • EDUCATIONAL ROBOTICS ON THE PREVENTION OF MENTAL DISORDERS IN THE SCHOOL ENVIRONMENT

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Apr 26, 2021


  • Show Abstract
  • In this work, we propose to study and verify the potential of using Educational Robotics in the classroom to improve cognitive functions and at the same time act in the prevention of the occurrence of mental disorders, a problem that has hindered the socio-cultural development of many young people today. It is worth mentioning that there are studies verifying the effectiveness of Educational Robotics with children and adolescents in order to assist in the diagnosis and treatment of the autistic spectrum and in visual impairment, but we do not find in the literature a study similar to the one proposed in this work. Furthermore, it is already demonstrated in the literature that Educational Robotics improves the child's cognitive functions and also their and teachers' self-esteem. During the work, from the analysis of collected data, we were able to verify strong indications that children and adolescents who take educational robotics classes are less susceptible to major problems of depression, stress, among other types of mental disorders. To reach this inference, we developed and applied questionnaires for teachers and students, from which variables were determined to be analyzed, such as psychomotor, cognitive and affective. The questionnaires were applied in the practical phase of the Brazilian Robotics Olympiad that took place at the Federal Institute of Rio Grande do Norte, Natal, Brazil. These data were submitted to an analysis and later verification through qualitative and quantitative methodologies on the educational robotics tool used.

     
8
  • RODRIGO DE ANDRADE TEIXEIRA
  • Power Quality Analysis Applied to a Three-Phase PWM Rectifier System Using the One-Cycle Control Technique.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ELMER ROLANDO LLANOS VILLARREAL
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • RICARDO FERREIRA PINHEIRO
  • Data: Apr 27, 2021


  • Show Abstract
  • This work proposes the use of the one-cycle control technique to control a three-phase rectifier based on boost topology, without the use of voltage sensors at the coupling point of the system. Furthermore, unlike most of the works developed with the OCC technique, a digital implementation using Texas Instruments' DSP TMS 320F28335 was used. The objective of the proposed implementation is to obtain a sinusoidal current at the rectifier input with a power factor as close as possible to unity, while the rectifier output is controlled at a fixed voltage value. To evaluate the proposed system, simulations were performed in Matlab and PSIM software and the practical results were verified using a laboratory prototype.

9
  • PAULO VICTOR QUEIROZ CORREIA
  • DETECTION AND CLASSIFICATION PERFORMANCE ANALYSIS OF FAILURES IN INDUSTRIAL PROCESSES USING LSTM NEURAL NETWORKS WITH DATA COMPRESSION TECHNIQUES

     
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • CELSO JOSÉ MUNARO
  • Data: Jun 30, 2021


  • Show Abstract
  • Industry 4.0 set a paradigm shift in industrial process monitoring and control. It installed several sensors in different parts of the plant, connecting these industrial processes with the Internet of Things and Cloud Computing. Although, the data generation growth demanded engineers build proper environments to process and store the absurd amount of data. This growth caused an increasing energy consumption, computational complexity and environmental degradation. Therefore to address these demands, this dissertation proposes efficient approaches to perform Fault Detection and Identification in industrial processes. The first approach consists of using Symbolic Aggregate Approximation (SAX) to compress process variables to reduce the load on data warehouses. Then, we train a Long Short-Term Memory (LSTM) neural network with those compressed inputs to perform fault detection. Finally, the second approach addresses efficient edge computing systems, performing LSTM neural network compression with pruning technique. The compression reduces the memory usage and number of operations of these networks, saving energy and accelerating inference speed in edge computation. To assess the performance of both approaches, we use the Tennessee Eastman Process (TEP) as the benchmark with classification metrics of accuracy, precision, recall and F1-Score. We are also going to analyze the compression efficiency of both approaches, studying their viability and parameter reduction in LSTM networks.

     
10
  • MAXWEL DA SILVA SANTOS
  • Improved Margin Voltage Control Strategy for Multi-terminal High Voltage Direct Current Systems based on the Modular Multilevel Converter for Robustness Towards Disturbances

  • Advisor : LUCIANO SALES BARROS
  • COMMITTEE MEMBERS :
  • LUCIANO SALES BARROS
  • CARLOS EDUARDO TRABUCO DOREA
  • FLAVIO BEZERRA COSTA
  • RODRIGO ANDRADE RAMOS
  • Data: Jul 2, 2021


  • Show Abstract
  • In modern systems, multi-terminal high-voltage Direct Current (MTDC) transmission technology has been considered the key technology for long-distant bulk electric power transmission, asynchronous grid interconnections, and offshore wind energy converter systems (WECS). The main purpose of an MTDC grid is to share power among the AC grids. However, this technology presents challenges in its operation and control. Therefore, for its control is necessary the use of appropriate control system strategies, such as master-slave, margin voltage, voltage droop, and their combinations. In this work, it is proposed a modification in the DC voltage control loop of the margin voltage control strategy aiming to avoid degradation of current control and to increase the supportability to disturbances in the power grid. This modification is based on closed-loop control of the power and feed-forward compensation of the DC grid power. The performance of the proposed method was assessed in a four-terminal meshed MTDC system topology based on the multilevel modular converter (MMC) under abnormal operating conditions and a comparison with the margin voltage and voltage droop control strategies was accomplished. The operation scenarios consider challenging and common failures for MTDC network control systems such as power flow variation in a converter station, open-circuit of a DC transmission line, and failure of a converter station. The proposed control presented the best performance, obtaining a new balance of power flow with less power and voltage oscillations.

11
  • ISMAEL ALVES DE AZEVEDO
  • Comparison of Control Strategies for Squirrel-Cage Induction Generator-Based Wind Energy Conversion Systems

  • Advisor : LUCIANO SALES BARROS
  • COMMITTEE MEMBERS :
  • LUCIANO SALES BARROS
  • ANDRES ORTIZ SALAZAR
  • DANIEL BARBOSA
  • Data: Jul 5, 2021


  • Show Abstract
  • The squirrel cage induction generator is a robust and low cost alternative to variable speed wind energy conversion systems. For this type of generator, direct torque control, direct stator-field-oriented control, direct rotor-field-oriented control, stator-flux slip control and rotor-flux slip control can be used for maximum power point tracking. Stator-flux slip control and direct torque control have simple schemes with fast dynamic responses, since they do not have internal current controllers. However, stator-flux slip control presents high inrush-current and a poor dynamic response and direct torque control presents high torque ripples and poor performance at low speeds. On the other hand, rotor-flux slip control, direct stator-field-oriented control and direct rotor-field-oriented control have fast dynamic response, low inrush current and low error at maximum power point tracking, but have current controllers and offer a larger complexity in the control design. The objective of this work is to define the most suitable control strategy by evaluating the following performance indexes simultaneously: maximum power point tracking, total harmonic distortion, inrush current and dynamic response. Simulations are performed in order to analyze the performance of the control strategies. Tests were carried out for the five control strategies and the direct rotor-field-oriented control presented the best trade off considering maximum power point tracking, total harmonic distortion and dynamic performance, despite it does not have the best inrush current.

12
  • DANIEL DE LUCENA FLOR
  • Acoustic Noise Evaluation inside Vehicles under Different Traffic Conditions

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • EMANUEL BEZERRA RODRIGUES
  • ALLAN DE MEDEIROS MARTINS
  • DANILO DE SANTANA PENA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jul 23, 2021


  • Show Abstract
  • This work aims to analyze the interior acoustic noise in a vehicle under several traffic conditions by comparing different statistical models used for evaluating noise impulsiveness. Initially, we present the importance of studying the sound quality for the development of multimedia and control applications and of smart vehicles. Next, we discuss previous works on the acoustic channel inside vehicles, as well as the approaches to statistically model this type of channel. The measurement setup we used and the analyses of the collected data are presented in order to highlight which measurements conditions contribute the most to the interior noise levels and to impulsivity.

13
  • GABRIEL LUCAS ALBUQUERQUE MAIA SIGNORETTI
  • An online evolving algorithm for automatic data compression in IoT scenarios

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • GUSTAVO BEZERRA PAZ LEITAO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • JUAN MOISES MAURICIO VILLANUEVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jul 23, 2021


  • Show Abstract
  • With the advancement and mass adoption of solutions in the fields of Internet of Things (IoT) and connected cities, the number of devices and sensors connected to the network tends to grow exponentially. In this scenario, the transmission and storage of the growing volume of data bring new challenges. When devices transmit potentially irrelevant or redundant data, there is increased energy and processing waste, as well as unnecessary use of the communication channel. Thus, local data compression solutions on the IoT devices themselves become increasingly attractive, enabling the elimination of samples that would have little or no contribution to the application, in order to significantly reduce the volume of data needed to represent the information. However, such devices present on the market today have serious storage and processing power limitations. In order to circumvent these limitations, the TinyML field emerges, which seeks ways to implement machine learning models in low-power devices. Given this context, one of the sectors that can benefit most from these new technologies is the automobile industry, as currently all cars produced must be instrumented with a series of sensors. In this way, by connecting an intelligent device to the vehicle, it is possible to process the data locally and transmit it to a remote server later. In this context, the present work proposes the development of a new online, unsupervised, and automatically adaptable data compression algorithm for IoT applications. The proposed approach is called Tiny Anomaly Compressor (TAC) and is based on data eccentricity and does not require pre-established mathematical models or any assumptions about data distribution. To test the effectiveness of the solution and validate it, two tests were carried out with different objectives. First, a comparative analysis on two real-world datasets was developed with two other algorithms from the literature, the Swing Door Trending (SDT) and the Discrete Cosine Transform (DCT). Finally, the proposal was embedded in an IoT device based on an Arduino and connected to a car to verify the impact of the algorithm on the processing time of the system's primary operations. Preliminary results show that it is possible to achieve significant compression rates without significant impacts on the generated error and system processing.

14
  • ANA THERESA FERNANDES DE OLIVEIRA MANCINI
  • Design of Dynamic Output Feedback Controllers for Linear Systemas Under Constraints

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • AMANDA DANIELLE OLIVEIRA DA SILVA DANTAS
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • CARLOS EDUARDO TRABUCO DOREA
  • Data: Aug 4, 2021


  • Show Abstract
  • In this work an improvement in the design of output feedback controllers using invariant sets is proposed. Controlled invariant sets have been widely used to solve constrained systems problems. Despite having been well studied in state feedback control, the use of controlled invariant sets for output feedback is still little explored. A state observer is incorporated into the compensator structure in order to obtain a dynamic compensator. The proposed output feedback controlled invariant set is constructed from a conditioned invariant set and a controlled invariant set. The uncertainty of states is reduced using the contraction of the conditioned invariant set. An output feedback control strategy is to minimize the admissible states consistent with the measurements one step ahead. Here we propose the optimization of this strategy by using the result of the linear programming problem as an additional information in the calculation of the next control action in order to accelerate convergence. Results obtained from the optimization strategy using the conditioned invariant set as a target for the optimization of the distance to the origin are also analyzed. First, the theory of invariant sets and its application in state feedback control is presented. Next, the strategies for static and dynamic output feedback are presented without the use of additional information in the calculation of the control action. Finally, the design of output dynamic and static feedback controllers using the optimization strategies with additional information is presented and the results obtained with both strategies are compared.

15
  • MILLENA MICHELY DE MEDEIROS CAMPOS
  • RF Signal Based Classification of Number of People in an Environment: A Machine Learning Approach

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • EDUARDO RODRIGUES DE LIMA
  • LEONARDO HENRIQUE GONSIOROSKI FURTADO DA SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Aug 26, 2021


  • Show Abstract
  • This work proposes a technique for counting people in an already populated environment. Initially, a survey is made of the technologies and solutions designed for this purpose. As a proof of concept, a counting solution is analyzed for a small number of people, applying machine learning to the descriptive statistics of an RF signal. Finally, the classification results are presented for a more realistic scenario, with up to 350 people in the environment, using a software-defined radio measurement system for data collection. The results show significant precision in counting the number of people by classification in groups of individuals.

16
  • RAFFAEL SADITE CORDOVILLE GOMES DE LIMA
  • A parallel software-defined ultra-low-power receiver for a satellite message forwarding system

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • KAYO GONCALVES E SILVA
  • TIAGO TAVARES LEITE BARROS
  • HENRIQUE COTA DE FREITAS
  • JOSÉ MARCELO LIMA DUARTE
  • Data: Sep 17, 2021


  • Show Abstract
  • In the beginning, satellite communications faced a major challenge of putting complex on-board processing, due to the high cost, energy consumption, weight, and volume of the equipment. With the advancement of microelectronics, today we have miniaturized devices with low cost and low power consumption. The CubeSat standard is an alternative for replacing large satellites in specific applications, due to its size, there are restrictions on energy consumption. In this paper, we present a parallel implementation of pi/3-Phase Shift Keying multi-user receiver in the GAP8 Parallel Ultra-Low Power processor for low earth orbit (LEO) nanosatellite communication system. The near-threshold operation will guarantee high energy efficiency and parallelism with high-efficiency processing. The system consists of pi/3-PSK signals transmitted by terrestrial platforms, satellite links, noise, and receiver. The noise channel that was used in the system is Additive White Gaussian Noise (AWGN), loss of power due to the satellite communication link is considered. The Channel coding that was used in Manchester. A MatLab implementation of the receiver will be used as a reference model for validating the receiver implementation on GAP8. The receiver validation in GAP8 will be done by comparing its output with that of the reference model for the same input.

17
  • IAN DA SILVA VIGANÓ
  • Fuzzy Interval Theory Applied in a Magnetic Levitation System Control

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • MÁRCIA LISSANDRA MACHADO PRADO
  • OSCAR GABRIEL FILHO
  • Data: Oct 18, 2021


  • Show Abstract
  • Magnetic levitation teory attracts a lot of interest from the academic community currently, as it has a great potential in present promising technologies to the market, mainly in the passenger and cargo transportation sector and in the industrial sector, providing a great positive impact for society and contributing to the your well-being. Under this premise this work proposes to analyze the application of type-2 fuzzy control as a better alternative for control design for systems of this class, analyzing the positive characteristics of the application of this control technique in the face of type-1 fuzzy. The controllers were designed and tuned manually, in order to observe if the extra degree of freedom provided by the type-2 fuzzy technique presents a superior performance. The experimental results show that the type-2 fuzzy controller provides a superior performance to its type-1 counterpart in different aspects. With this methodology, the best characteristics of the different classes of control systems can be combined to achieve a more efficient and intelligent control scheme.

18
  • WYSTERLÂNYA KYURY PEREIRA BARROS
  •  Hardware Implementation of the Otsu’s Method Applied to Real-Time Worm Segmentation

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • RAFAEL BESERRA GOMES
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • MARCO ANTONIO GARCIA DE CARVALHO
  • Data: Nov 17, 2021


  • Show Abstract
  • Behavioral genomic studies employing the worm Caenorhabditis elegans have aided the discovery of new gene-behavioral associations and the screening of new drugs. High-resolution cameras record experiments with this worm, generating videos that computational solutions will later process for automated behavioral analysis. Because of the large volume of data to be processed, these analyses usually have to be performed offline. However, it is desired to develop a high-throughput implementation capable of operating in real-time, seeking to reduce the memory occupation by storing videos and allow the realization of new kinds of experiments. One way to speed up the algorithms employed is through the use of reconfigurable computing. Therefore, this work proposes the hardware development of the Otsu method for worm segmentation in real-time. The proposed implementation was developed in Field Programmable Gate Array (FPGA) using a fully parallel strategy with fixed-point representation. Architecture details are presented, as well as synthesis results related to the hardware area occupation, throughput, and dynamic power consumption. Results about validation of the implementation using images of the worms are also provided. The data show that the proposed architecture can achieve high speedups compared to similar work presented in the literature, besides allowing the segmentation of worms in real-time

19
  • IGOR MACEDO SILVA
  • CEVERO: an open hardware processor for aerospace missions

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • FERNANDA GUSMÃO DE LIMA KASTENSMINDT
  • Frank Kagan Gürkaynak
  • SAMUEL XAVIER DE SOUZA
  • TIAGO TAVARES LEITE BARROS
  • Data: Dec 3, 2021
    Ata de defesa assinada:


  • Show Abstract
  • The space environment is a harsh environment for digital circuits. The effects of space radiation on the circuit might result in malfunction and, as a consequence, jeopardize the security and execution of space missions, manned or not. Therefore, there was a need to develop digital circuits which can withstand radioactive particle’s strikes and, nowadays, there are several processor technologies that can indeed work safely under such conditions. However, these technologies generally involve proprietary transistor fabrication steps or proprietary cell libraries which inhibit usage and development. There is, nonetheless, another set of architectural methods which operate on a higher abstraction level and are arguably as reliable as the mentioned techniques for a set of space missions. This work uses these techniques to develop the CEVERO, a general-purpose processor base on the existing PULP Platform, which uses architectural modifications such as redundancy and other methods to detect and correct faults, for deploying on aerospace missions.

20
  • CASSIANO PERIN DE CARVALHO
  • Deep Learning Architecture for Automatic Modulation Classification in Time-Varying Fading and Impulsive Noise Channels.

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • PEDRO THIAGO VALERIO DE SOUZA
  • TALES VINÍCIUS RODRIGUES DE OLIVEIRA CÂMARA
  • Data: Dec 10, 2021


  • Show Abstract
  • The automatic modulation classification (AMC) allows identifying the kind of modulation of the received signal, being a key part of the development of cognitive radio devices that adapt the type of modulation to the characteristics of the communication environment. Several types of research on AMC have been done based on the analysis of the modulation signals and using its parameters for developing powerful feature descriptors to be used on this automatic classification. Recently, a new trend appears related to the use of architectures based on deep learning for this classification. Hence, in this work, we propose to use methods based on deep learning to classify the modulation type of a signal in an environment with doppler fading and impulsive noise. We studied and propose a model based on CNN that has shown to be comparable to the state-of-the-art methods.

21
  • JANAILSON MACIEL DE QUEIROZ
  • Study of DFIG Differential Protection Including Analysis of Interturn Faults

  • Advisor : LUCIANO SALES BARROS
  • COMMITTEE MEMBERS :
  • DANIEL BARBOSA
  • FLAVIO BEZERRA COSTA
  • LUCIANO SALES BARROS
  • RICARDO AUGUSTO SOUZA FERNANDES
  • Data: Dec 15, 2021


  • Show Abstract
  • With the increase in interest in renewable energies in the world, the importance of research in wind energy, methods, and associated technologies has grown. The increase in wind turbines connected to the electrical systems also brought with it new challenges related to the stability of the system and protection of its components. Differential protection is used in many electrical system components and for DFIG-based wind turbines this protection has been proposed recently. Therefore, this work proposes criteria in the decision-making of the differential protection based on the Park transform, which in addition to the restriction current also uses the voltage level and the direction of the currents at the stator terminals. In a simulation with DFIG operating at 1.51 MW, tests were carried out for internal and external faults to the protection zone, of the single-phase and threephase type with different levels of voltage drops. Inter-turn faults on the machine’s rotor and stator have also been tested with varying levels of defects. Thus, with the proper def inition of the operating logic, it was possible to show the effectiveness of the protection, with detection for all single-phase and three-phase faults within the protection zone, detection of faults in windings in the stator with 10% defect or more and detection of faults in the rotor windings with a defect of 20% or more.

22
  • THIAGO FIGUEIREDO DO NASCIMENTO
  • Modeling and Controllers Design for an Electromagnetic Frequency Regulator Applied to Wind Systems

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • EVANDRO AILSON DE FREITAS NUNES
  • PAULO VITOR SILVA
  • RICARDO FERREIRA PINHEIRO
  • Data: Dec 17, 2021


  • Show Abstract
  • With the high penetration of distributed generation (DG) systems based on wind energy sources, it is necessary to develop technologies for improving the efficiency of system operation. Among the solutions proposed in the literature, the Electromagnetic Frequency Regulator (EFR) device has proven to be an attractive solution for improving the performance of the wind systems. This work proposes a dynamic modeling and control design for EFR applied to a wind systems. The system controllers parameters are designed by using root-locus method (RLM) in order to realize desired dynamic performance. Besides, a stability analysis for closed-loop system is assessed to obtain the operating limits. Finally, simulation results demonstrate the effectiveness of the proposed dynamic modeling and system controllers performance.
Thesis
1
  • THIAGO HENRIQUE FREIRE DE OLIVEIRA
  • Reinforcement Learning Algorithms for Multiobjective Optimization Problems

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALUIZIO FAUSTO RIBEIRO ARAÚJO
  • DANIEL SABINO AMORIM DE ARAUJO
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • JORGE DANTAS DE MELO
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Jan 11, 2021


  • Show Abstract
  • Multi-objective optimization problems depict real situations and therefore, this class of problems is extremely important. However, even though it has been studied for decades, this class of problems continues to provide challenging situations, especially by the continuing lack of effective techniques. Among all the difficulties that we can find in the optimization of multiple objectives simultaneously, whether conflicting or not, one of the main difficulties found by the algorithms and existing approaches is the need for a priori knowledge of the problem, causing a predefined importance for each of the objectives. When dealing with this class of problems through reinforcement learning, two approaches are predominant: single policy (single-policy) and multiple policies (multi-policy). Algorithms and techniques that use the first approach suffer from the need for prior knowledge of the problem, an inherent characteristic of multi-objective problems. The second approach has other difficulties, such as: limiting the set of solutions and high computational cost. Given this presented context, the work proposes two hybrid algorithms, called Q-Managed with reset and Q-Managed without reset. Both are a hybridization of the Q-learning algorithm and the ε−constraint approach, respectively belonging to reinforcement learning and multi-objective optimization. In summary, the proposed algorithms work as follows: Q- Learning is used for environment exploration, while the ε−constraint approach is used for the environment dynamic delimitation, allowing to keep intact the essence of how the algorithm Q-Learning works. This delimitation has the following purpose: to impose the learning agent can learn other solutions by blocking actions that lead to solutions already learned and without improving them, that is, solutions to which the learning agent has already converged. This blocking actions feature is performed by the figure of a manager, where it is responsible for observing everything that occurs in the environment. Regarding the difference between the proposed algorithms, basically it is the choice of whether or not to take advantage of the knowledge already acquired of the environment after a solution is considered to be learned, that is, the learning agent has converged to a particular solution. As a way of testing the effectiveness of Q-Managed two versions, traditional benchmarks were used, which were also adopted in other works, thus allowing a fairer comparison. Thus, two comparative approaches were adopted, the first of which was through the implementation of third-party algorithms for direct comparison, while the second was done through a common metric to everyone who used the same benchmarks. In all possible tests, the algorithms proposed here proved to be effective, always finding the entire Pareto Front.

2
  • SERGIO NATAN SILVA
  • Reconfigurable computing applied to reduce latency in control and prediction systems associated with tactile internet

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • JOSÉ CLÁUDIO VIEIRA E SILVA JUNIOR
  • LEONARDO ALVES DIAS
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Jan 28, 2021


  • Show Abstract
  • Tactile internet is the current technological advance for the Internet. The devices associated with this new internet paradigm will be responsible for man-machine applications with the sending of touch information and the other stimuli already sent. Thus, it is necessary to guarantee an extremely low latency between the devices that make up the tactile interaction. This latency is associated with propagating information through the communication channel, processing power of local devices, and complexity of the techniques being executed, among others. Accordingly, this work proposes using dedicated hardware-based reconfigurable computing to reduce latency in control and prediction systems applied to tactile Internet. Two approaches are proposed to address the problem of latency. In the first approach, reconfigurable hardware is proposed for an intelligent control system based on Fuzzy logic. The system is a Takagi - Sugeno Fuzzy-PI type controller that aims to reduce the latency associated with processing data using a tactile tool. The implementation uses a fully parallel strategy associated with a hybrid bit format scheme (fixed-point and floating-point). In the second approach, the implementation in reconfigurable hardware of linear and nonlinear prediction techniques is proposed. In the nonlinear case, a technique based on multilayer Perceptron artificial neural networks is used. In this approach, prediction techniques are used to minimize the impacts caused by delays and loss of information associated with tactile Internet. The proposals were tested for a field-programmable gate array (FPGA) on the Virtex 6 xc6vlx240t-1ff1156 platform. Data related to hardware occupation and throughput associated with the target platform are presented, and a comparison between results through simulation and implementations in dedicated hardware. The results are superior to those presented in other studies in the literature.

3
  • AUGUSTO CÉSAR REBOUÇAS DE BRITO
  • BOW-TIE ANTENNA INTEGRATED TO A REFLECTIVE FSS FOR 5G SYSTEM APPLICATIONS

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • CUSTÓDIO JOSÉ OLIVEIRA PEIXEIRO
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Feb 2, 2021


  • Show Abstract
  • In recent years, advances in wireless communication systems and the growth in the number of applications have made it attractive to use compact multiband and broadband antennas for both commercial and military communications. The most common examples are found in the variety of portable wireless communication devices, such as: smartphones, handsets, palmtops and laptops, among others. The development of different wireless technologies, such as GSM (Global System for Mobile Communications), RFID (Radio Frequency Identification), Bluetooth, Wi-Fi and WiMAX, has served as a motivation to boost searches in search of lighter devices , compact and low cost, as is the case of planar microstrip antennas. The development of antennas with these characteristics is still a challenge to current research. This work aims at the study, design, manufacture and measurement of new planar antenna geometries, with openings in the ground plane and the use of FSS (Frequency Selective Surface), aiming to reduce its size, volume and weight as well as gain of antennas, to meet the demands of the services offered by the Mobile Systems 5G, for example. The insertion of air layers between the antenna and the EBG structure was also used aiming at a greater degree of freedom to adjust the resonant frequencies. Computational simulations with the objective of predicting the values of the parameters that characterize the proposed structures were performed through the CST and HFSS 13.0 softwares. Prototypes were manufactured and measured. A good agreement was observed between the simulated and measured results.

4
  • ANDOUGLAS GONÇALVES DA SILVA JÚNIOR
  • Holographic Projection with Deep Learning for Microparticles Detection from Water Samples

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • VITTORIO BIANCO
  • COSIMO DISTANTE
  • ESTEBAN WALTER GONZALEZ CLUA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Feb 5, 2021


  • Show Abstract
  • This thesis proposes a complete holographic system to be applied in scientific research and monitoring, which is able to detect microparticles from the holographic projection of water samples, using a deep learning approach. The system proposed in this thesis uses digital holography techniques to acquire holograms from these particles (a device was built for this purpose), reconstruct them numerically by obtaining phase and intensity information, and classify them using machine learning models. In addition, we have developed an application on the web capable of performing all stages of the hologram reconstruction and the classification process using trained models, which is also available. The need for studies on particles that are invisible to the naked eye and that can be dangerous to the health of living beings is an increasingly important research topic and there are many concerns about it. An example is the various types of microplastics found on a large scale in different parts of the planet, even within the human body. Another particle that can help identify microplastics and that can be used to calculate bioindicators of water quality are diatoms. The detection of microplastics and diatoms is subject to difficult studies due to their size, in the order of the micrometer.

5
  • ALEX FABIANO DE ARAÚJO FURTUNATO
  • Analytical modeling for performance prediction of parallel applications in symmetric architectures considering variations in the data access delay

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • Arthur Francisco Lorenzon
  • EDSON BORIN
  • Data: Feb 9, 2021


  • Show Abstract
  • Several analytical models created since Amdahl's pioneering work have explored aspects such as variation in the size of the problem, memory size, communication overhead, and synchronization overhead, but delays in accessing data are considered constant. However, such delays can vary, for example, according to the number of cores used, the relationship between processor and memory frequencies, and the problem's size. Given different problem sizes and the large number of possible configurations of operational frequency and number of cores than current architectures can offer, speedup models suitable for describing such variations among these configurations are quite desirable for offline or online scheduling decisions. A new analytical performance model that considers variations in the average data access delay to describe the limiting effect of the memory wall in parallel applications in homogeneous shared memory architectures is presented in this thesis. The experimental results indicate that the proposed modeling captures the application's behavior well. Besides, we show that considering parameters that reflect the applications' intrinsic characteristics, the proposal presented in this work has significant advantages over statistical models such as those based on machine learning. Our experiments also show that conventional machine learning modeling may need about an order of magnitude more measurements than the proposed model to achieve the same level of precision achieved by the proposed model.

6
  • FELIPE FERREIRA DE ARAUJO
  • Wireless communications, Microstrip antennas, Metasurfaces

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ADAILDO GOMES D ASSUNCAO
  • VALDEMIR PRAXEDES DA SILVA NETO
  • ALFREDO GOMES NETO
  • JEFFERSON COSTA E SILVA
  • Data: Feb 18, 2021


  • Show Abstract
  • The microstrip antennas are the object of study in several research fields due to their advantages such as: small thickness, reduced weight and easy integration of electronic circuits. Similarly, the evolution observed in the development of microstrip antennas has also been noted in relation to the metasurfaces, a two-dimensional version of a metamaterial. Metasurfaces are artificial materials that are not found in nature and have unconventional electromagnetic characteristics, such as the index of refraction and coefficients of electrical permittivity and negative magnetic permeability, in addition, they have the ability to be used in planar structures, such as microstrip, without interfering with its traditional geometry. The objective of this work is to increase the bandwidth of a microstrip antenna using a new metasurface model. This new geometry is used to generate high order modes in the antenna and with rotation of the metasurface in relation to the antenna we can overlap the modes and obtain a large bandwidth. The proposed antenna presents bandwidth from 5.1 GHz to 8.0 GHz and can be applied in Wi-Fi 5 and 6. Numerical results were chosen with the Ansys HFSS software. A prototype was built and built for S11 and gains were made. The numerical and experimental results are in agreement.

7
  • PHILIPPI SEDIR GRILO DE MORAIS
  • Salus: A Digital Health Architecture Applied to Syphilis Case Management


  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • GUILHERME MEDEIROS MACHADO
  • ANGELICA ESPINOSA BARBOSA MIRANDA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ION GARCIA MASCARENHAS DE ANDRADE
  • JAILTON CARLOS DE PAIVA
  • KARILANY DANTAS COUTINHO
  • LYANE RAMALHO CORTEZ
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Mar 26, 2021


  • Show Abstract
  • Syphilis in Brazil grew by over 5000% between 2012 and 2017, this drew the attention of the Ministry of Health, which in 2017 declared a syphilis epidemic Brazil. The hardest side of syphilis is in vertical transmission, that is, when a pregnant woman transmits Treponema Pallidum to her baby. The Federal Court of Accounts (TCU - Brazil), through a serious and in-depth audit regarding the increase in syphilis cases in Brazil, made several notes and recommendations, among them the need to develop tools and technologies that make it possible to monitor more efficiently the evolution of syphilis countrywide. However, when it comes to monitoring it is important to look beyond epidemiological issues, diagnosis, care, treatment and cure. These factors are important, for example, to eliminate vertical transmission of syphilis and, consequently, congenital syphilis, the latter being one of the greatest challenges for Brazil. In this context, it is necessary, therefore, that the actions to face syphilis in Brazil are coordinated between Health Surveillance and Health Care. These two areas, despite being conceived by the Brazilian Health System (SUS) as essentially articulated with each other, operate in a large part of the country in a dichotomous way, including in the Ministry of Health itself. This sometimes occurs due to the lack of integration between the teams that they work in different areas of health, or because the technologies made available by DATASUS are far from understanding the need to mediate a logic of integration between these strategic areas of SUS. The present doctoral thesis is, therefore, situated in this dimension, it brings in its discussion the development of a technological architecture that in fact is a digital health solution that mediates the integration between Health Surveillance and Health Care through technology. both, it incorporates in its flow the management of cases of Syphilis in the territory, that is, in the municipality, places where health is closest to the population. At the same time, it produces epidemiological and care indicators on syphilis. The construction and validation of this architecture was carried out in the city of Natal-RN and the entire discussion surrounding the development and application is presented in this doctoral thesis.


8
  • EVANDRO AILSON DE FREITAS NUNES
  • Contributions to Speed Control Strategy Applied to Speed Multiplication of Frequency Electromagnetic Regulator.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • RICARDO FERREIRA PINHEIRO
  • DARLAN ALEXANDRIA FERNANDES
  • PAULO VITOR SILVA
  • Data: Apr 8, 2021


  • Show Abstract
  • Currently, incentives for clean energy generation have been increasing considerably due to the limitation of fossil fuels, until then used in abundance. Among these alternative sources, wind energy has been receiving special attention from the energy sector and scientific community and, in Brazil, which in 2017 took the 8th position in the world ranking of countries with the largest installed capacity in wind farms, the participation of this natural resource in the energy matrix shows an exponential growth.
    Speed multiplication is one of the most important steps in wind power generation systems and it is traditionally performed by means of mechanical gearboxes. However, due to its reduced service life, high failure ratio and because it is considered an intermittent noise source, the search for new speed multiplication devices for gearboxes replacement has become an important research topic to increase the efficiency of wind power systems. Electromagnetic Frequency Regulator (REF) is an example of an alternative application that allows a high speed gain while making use of the main advantages of a squirrel cage rotor induction machine. The current control system of the REF consists of the conventional PID strategy, which has several limitations widely discussed in the literature. This strategy also limits REF performance at different points of operation. In this work, a control strategy based on artificial intelligence (AI) of fuzzy logic will be adopted for REF speed regulation, with the aim of eliminate the dependence of the control system in relation to the physical parameters of the prototype. Simulation and experimental results will be presented for the validation of the efficiency of the proposed control strategy.

9
  • BRUNO VICENTE ALVES DE LIMA
  • Semi-supervised Learning by Deep Learning Techniques and Information Theory

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DANIEL SABINO AMORIM DE ARAUJO
  • IVAN NUNES DA SILVA
  • JORGE DANTAS DE MELO
  • VINICIUS PONTE MACHADO
  • Data: Jun 9, 2021


  • Show Abstract
  • The expressive growth of modern data sets, combined with the difficulty of obtaining information about labels, has made semi-supervised learning one of the problems of practical importance in modern data analysis. In most cases, obtaining a set of data with enough examples to induce a classifier, can be costly, as it is necessary to carry out data labeling by a specialist. Unlabeled data is easier to obtain but more difficult to analyze and interpret. In of semi-supervised learning problem, there is a database formed by a small part labeled and a larger part not labeled, being possible two aspects: semi-supervised classification and semi-supervised clustering. With this, this work aims to apply models that use Deep Learning techniques in semi-supervised learning, where a neural network is trained, in this case, an autoencoder using unlabeled data. Then, an additional layer is embedded in the encoder. This new layer has its weights initialized by the K-means ++ algorithm and adjusted through the backpropagation algorithm using information theory learning. The labeled data is assigned to the clusters generated by the encoder, influencing the unlabeled, cluster by cluster, thus labeling the non-labeled data that was previously clustered. With the experiments carried out, it was noted that the satisfactory performanceof the proposed model when compared with other semi-supervised algorithms, both the classics such as self-training and co-training, as well as other more recent works, showing the proposed model feasibility for the learning semi-supervised problem.

10
  • FELIPE OLIVEIRA SIMÕES GAMA
  • Development of Wavelet Coding and IEEE 802.15.4-based Communications Systems for Industrial Wireless Sensor Networks

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ELMER ROLANDO LLANOS VILLARREAL
  • JEFFERSON DOOLAN FERNANDES
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RODRIGO SOARES SEMENTE
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jun 24, 2021


  • Show Abstract
  • With the advent of Industry 4.0 wireless communication has become a trend for signal transmission in industrial environments, sparing features and enabling new applications when compared to wired communications systems. In this context, the transmission of data between sensor and controller within control loop using wireless interconnected nodes is susceptible to the degenerative effects produced by the multiple propagation paths. Nevertheless, most industrial wireless sensor network standards provide no error-control mechanism, which would be useful for improving communication reliability and efficiency, as they are based on the IEEE 802.15.4 protocol. In order to minimize these destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, the wavelet coding is presented as a good alternative for the nodes interconnected by wireless communication due to its robustness to the effects of the wireless channel and its low computational complexity. This work is based on an approach that explores wavelet matrices for the design of finite impulse response (FIR) filters used in the coding of the complex signals generated by the physical layer of the IEEE 802.15.4 protocol. A new transmission system is proposed that is still based on the IEEE 802.15.4 protocol, which allows to maintain the interoperability with legacy systems and to still achieve superior performance to the requirements for the establishment of control systems by networks wireless. Specifically, it is expected that the proposed system will increase the reliability of the communication and thereby decrease the retransmission events caused by the wireless channel over the transmitted data packets. In particular, the communication delays derived from these retransmission events seriously interfere with the control system, as it does not guarantee the time constraints of the control signal. In addition, an important point regarding the performance of the proposed system is the possibility to improve the reliability of the communication without diminishing the spectral efficiency. The proposed system also allows for an adaptive performance in terms of the coding rate and parameters of the wavelet matrix, without a significant increase in the implementation complexity. The proposed communication system will be implemented using the software concept radio concept in the GNU Radio development environment. The performance of the communication system will be evaluated in terms of bit error rate (BER) versus Eb /N0 and spectral efficiency, considering a time-variant channel model with flat Rayleigh fading. In addition, the effects of the transmission system will be considered in the controllability analysis of a control system.

11
  • SAMANTA MESQUITA DE HOLANDA
  • Study of Textile Metamaterial for Applications in Planar Antenna Substrates for WBAN Technology
  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • MARCOS SILVA DE AQUINO
  • HUMBERTO DIONISIO DE ANDRADE
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • Data: Jun 30, 2021


  • Show Abstract
  • The incessant development of implanted or promoted biometric sensors has led to the growth of Wireless Body Area Network (WBAN) technology. A WBAN can be used for many applications, such as monitoring of physiological signals and industrial communication applications. In this context, the textile antenna is an important element in wireless communication in smart fabrics, being the subject of recurrent research in industrial, military and medical applications. These antennas are flexible and, therefore, become convenient in applications where antenna rigidity is an obstacle This work presents the development of planar antennas with a textile metamaterial substrate in the 5G frequency range for WBAN applications, showing all process from making the substrates to the manufacture and testing of the antennas. Three types of textile substrate with different structure and composition were selected, and in each of them a conductive thread was inserted through different techniques (manual insertion, knitting and automatic sewing). The characterization of the materials was performed using simulations in the HFSS and the coaxial probe method, to obtain the electrical parameters. The antennas were designed and simulated to operate at 3.5 GHz, the best results being manufactured and tested in a Vector Network Analyzer (VNA). The results obtained in the simulations and tests were analyzed and the presence of a metamaterial characteristic was found in the loop and straight stitch geometries. Antennas with a textile metamaterial substrate had a lower resonance frequency than those with a dielectric textile substrate, indicating the possibility of reducing the dimensions of the device.

12
  • LEIDIANE CAROLINA MARTINS DE MOURA FONTOURA
  • A Novel Synthesis Method of Multiband FSS Based on Machine Learning for Wireless Communication Systems

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • CUSTÓDIO JOSÉ OLIVEIRA PEIXEIRO
  • HERTZ WILTON DE CASTRO LINS
  • LAERCIO MARTINS DE MENDONCA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Jul 9, 2021


  • Show Abstract
  • Frequency selective surfaces, or simply FSS, play a fundamental role in optimizing telecommunications systems by reducing undesirable signals, among other applications. Combining the dimensions and arrangement of the elements and defining the physical characteristics of these devices, such as thickness and permittivity of the substrate, can cause conflict of objectives and make more complex the analysis and synthesis of the FSS. In this context, the present work is a study on the application of supervised machine learning with the decision tree algorithm in the synthesis of frequency selective surfaces. For this, the sunflower (Helianthus annuus) was used as a base element, being an original and simplified geometry, with frequency response characteristics similar to those of fractal structures. The thesis work is thus divided in two parts: the proposed element characterization and synthesis of the multiband FSS. Initially, the evolution of geometry and design equations are presented. The intermediate and the proposed structures are numerically characterized using the commercial software Ansoft Designer, manufactured, and experimentally characterized, with good agreement between the simulated and measured results. In the second step, the sunflower geometry is partially modified to define parameterization variables. The Ansoft Designer numerically characterizes the value of each variable of the new geometry, and it generates the frequency responses without repetition. The decision tree algorithm performs the dataset classification and evaluation, and the random forest algorithm validates and confirms the results. This process and the synthesis of the FSS using the decision tree algorithm occur in less than 10 seconds, with accuracy greater than 90\%, meeting the desirable criteria, under two different scenarios. Based on these scenarios, two FSS are manufactured and experimentally characterized, obtaining results with good agreement. Moreover, it is observed that the agility and precision of this classification algorithm make the synthesis of the structures particularly interesting. Intuitive implementation, simplicity in training and validation, and an efficient data analysis model are highlighted.

13
  • DEMÉTRIOS ARAÚJO MAGALHÃES COUTINHO
  • Performance-Energy Trade-offs Prediction and Runtime Selection for Parallel Applications on Heterogeneous Multi-Processing Systems

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • DANIELE DE SENSI
  • ANTONIO CARLOS SCHNEIDER BECK FILHO
  • CARLOS AVELINO DE BARROS
  • HENRIQUE COTA DE FREITAS
  • SAMUEL XAVIER DE SOUZA
  • Data: Jul 15, 2021


  • Show Abstract
  • In the multi-core era, the size of the software operation space, i.e. hardware configurations that provide different software performance and energy consumption, is significantly larger. It becomes even more complex to choose a configuration that optimizes heterogeneous processors' performance and energy consumption. Heterogeneous multicore architectures offer flexibility in different core types and voltage and frequency pairings, defining a vast design space to explore. Furthermore, energy efficiency solutions are crucial on smaller devices as they can lead to longer battery life and a better user experience, including more complex applications. This thesis proposes a methodology to find performance-energy trade-offs for single parallel applications with dynamically balanced workloads running on HMP systems with a single instruction-set architecture (ISA). Our method devises novel analytical models for performance and power consumption whose parameters can be fitted using only a few strategically sampled offline measurements. These models are then used to estimate an application's performance and energy consumption for the whole configuration space. In turn, these offline predictions define the choice of estimated Pareto-optimal configurations of the model, which are used to inform the configuration that the application should execute. The methodology was validated on an ODROID-XU3 board for eight programs from the PARSEC Benchmark, Phoronix Test Suite and Rodinia applications. Energy savings of up to 59.77%, 61.38% and 17.7% were observed compared to the performance, ondemand and powersave Linux governors, respectively, with higher or similar performance. This method aims to provide an optimal start point for a runtime energy manager to make better decisions according to the given application's performance and energy consumption requirements and running system. Therefore, this thesis also proposes a strategy using the Pareto-optimal configuration selected by our models as an appropriate start point for a runtime support framework called Nornir.  This framework performs a  local search dynamically for a more desirable configuration of cores and frequency adapting to workload fluctuations and external interference.  Also, we extend our power model to predict the whole device's consumption, i.e. the sum of all internal components' consumption. This hybrid approach was employed on an ODROID-XU3 board on two multi-thread applications. Nornir starting with Pareto configuration can achieve up to 50% of energy savings compared to random starting configurations. We also observed that the performance and interactive Linux governors consumed up to 1.62X more energy than Nornir using Pareto.

14
  • TADEU FERREIRA OLIVEIRA
  • Use of Parallel and Distributed Processing in the Control Plan of Software Defined Networks to Increase Energy Efficiency in Data Center Networks

     
  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • SAMUEL XAVIER DE SOUZA
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ANDREY ELÍSIO MONTEIRO BRITO
  • CARLOS AVELINO DE BARROS
  • Data: Jul 30, 2021


  • Show Abstract
  • The main feature of the software-defined networks is the separation of the role of decision-making, known as control-plane, and the role of routing of the packages, known as data-plane. This separation allowed the introduction of the concept of network programmability, with which new applications could be implemented to interact directly with the operation of the networks. Today, these applications enable data center environments to match demand elastically, enabling cloud computing services. In this scenario, the datacenters became the prominent service providers, and one of its main costs is the consumption of energy in the infrastructure of servers and network equipment. Many papers indicate that software-defined network in datacenter networks allows for better energy efficiency, especially in the data plane. In this work, we present a strategy to – using parallel processing and distributed processing with lower operating frequency on the processing elements – reduce the energy consumption of the controllers on a software-defined network. The implementation of parallel and distributed versions of an SDN controller offers a fault-tolerant energy-aware solution to the presented problem.

     
15
  • LUIS ENRIQUE ORTIZ FERNANDEZ
  • Method to Measure, Model, and Predict Depth and Positioning Errors of RGB-D Cameras in Function of Distance, Velocity, and Vibration

  • Advisor : RAFAEL BESERRA GOMES
  • COMMITTEE MEMBERS :
  • BRUNO MARQUES FERREIRA DA SILVA
  • COSIMO DISTANTE
  • ESTEBAN WALTER GONZALEZ CLUA
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • Data: Aug 2, 2021


  • Show Abstract
  • This thesis proposes a versatile methodology for measuring, modeling, and predicting errors as the RMSE in the depth and the RPE in the camera positioning using data captured from an RGB-D camera mounted on the top of a low-cost mobile robot platform. The proposed method is divided in three stages, with the very first one consisting on the creation of ground truth data for both 3d points (mapping) and camera poses (localization). The next stage is the acquisition of a data set for RMSE and RPE errors calculation using the mobile platform with the RGB-D camera. Finally, the third step is to model and predict the errors in the measurements of depth and positioning of the camera as a function of distance, speed, and vibration. For this modeling and prediction stage, a simple approach based on MLP neural networks is used. This results in two networks, the N rmse Z for the depth error prediction and the N RPE for the prediction of camera positioning error. Experiments show that the N rmse Z and N RPE have an accuracy of ± 1% and ± 2.5%, respectively. The proposed methodology can be straight used in techniques that require an estimation of the error dynamics, as for example probabilistic robotics for localization and mapping, with RGB-D cameras mounted on UAVs, UGVs, and also USVs (including sailboats). Tasks that use RGB-D sensors, such as environmental monitoring, maintenance of engineering works, and public security, could rely on this approach to obtain the error information associated to the camera measurements (depth and positioning).

16
  • LUÍS BRUNO PEREIRA DO NASCIMENTO
  • Smooth and Safe Path Planning based on Probabilistic Foam for Autonomous Robotic Systems

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ALLAN DE MEDEIROS MARTINS
  • DENNIS BARRIOS ARANIBAR
  • EDUARDO OLIVEIRA FREIRE
  • PABLO JAVIER ALSINA
  • Data: Aug 30, 2021


  • Show Abstract
  • Planning a path for a robot to navigate between two points in a given environment and avoiding colliding with obstacles is one of the main issues for autonomous robotics. The search for short paths and reduced search time are aspects of most planning methods, but for applications where the robots interact directly with human beings, such as assistive robotics, ensuring a greater degree of safety in movements is a fundamental requirement. In this context, this Ph.D. thesis presents a set of new strategies for the planning of safe paths for autonomous robots. The methods developed are fundamentally based on the concepts of the Probabilistic Foam Method (PFM). PFM is a sampling-based path planning method capable of generating paths bounded by a set of connected bubbles, which guarantees a volumetric region in the free space for safe maneuverability. In order to compute the bubbles, PFM requires an explicit representation of the obstacles region in the configuration space, which is computationally impracticable considering its application for most problems. Thus, we applied a new strategy to compute bubbles without representing these obstacles regions. Besides, we present an analysis to reduce the number of PFM parameters. To improve the quality of the paths, two optimization procedures were implemented in order to reduce the path length and increase the path smoothness, maintaining the high clearance. New variants of PFM were developed to explore different mechanisms for the propagation of the foam, to ensure the planning of shorter paths, with short searching time, and guaranteeing paths with high clearance.  In order to demonstrate the main contributions of this Ph.D. thesis, some simulated experiments were performed, considering the path planning for two assistive robots: The first one is a lower limbs exoskeleton, with the tasks of overcoming obstacles, walking up and down a stair, resulting in smooth movements, with a more anthropomorphic pattern.  These results illustrate the ability of PFM to plan safe and smooth paths for open kinematic-chain robots without the explicit representation of the obstacles region in configuration space. The Smart Walker was the second robot considered in this work. It was possible to illustrate the planning of safe paths for a mobile robot with differential drive in addition to showing some aspects of the paths planned by the new methods developed.

17
  • JEAN MARIO MOREIRA DE LIMA
  • Representative Feature Extraction for Industrial Virtual Sensors Development: An Approach Based on Deep Learning

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • MARCELO AUGUSTO COSTA FERNANDES
  • ROBERTO KAWAKAMI HARROP GALVAO
  • WALLACE MOREIRA BESSA
  • Data: Sep 3, 2021


  • Show Abstract
  • Deep learning is growing in popularity in virtual sensor modeling problems - the soft sensors - applied to industrial processes of accentuated nonlinearity. Virtual sensors can generate estimates of process variables, which are associated with quality indexes in real- time. Thus, such sensors are a viable alternative when the variables of interest are difficult to measure due to some limiting factor: unavailability of hardware sensors or large measu- rement intervals. Traditional machine learning strategies show difficulties to model such sensors. Typically, industrial processes are highly nonlinear, and the amount of available labeled data is scarce. Due to that, the extraction of representative features present in the abundant amount of unlabeled data has become an area of interest in the development of virtual sensors. From the aforementioned premises, a new virtual sensor modeling tech- nique based on deep learning and representation, which integrates stacked autoencoders (SAE), mutual information (MI), long short-term memory (LSTM), and aggregation bo- otstrap , is proposed. First, in the unsupervised stage, the SAE structure is hierarchically trained layer-by-layer. After a layer’s training, MI analysis is conducted between the tar- get outputs of the model and the representations of the current layer to assess the learned characteristics. The proposed method removes irrelevant information and weights the re- tained ones. The given weights being proportional to the relevance of the representation. Therefore, this approach can extract deep representative information. In the supervised step, called fine-tuning, an LSTM structure is coupled to the tail of the SAE structure to address the intrinsic dynamic behavior of the evaluated industrial systems. Further, a ensemble strategy, called bootstrap aggregation, combines the models obtained in the supervised training phase to improve the performance and credibility of the virtual sen- sor. The proposal uses two industrial nonlinear processes, widely used as benchmarks, to evaluate the performance of the models generated by the proposed technique in the implementation of soft sensors. The results show that the proposed virtual sensors ob- tained better prediction performance than traditional methods and several state-of-the-art methods.

18
  • JULIANO COSTA LEAL DA SILVA
  • Modeling and Harmonic Impact Analysis of a Squirrel Cage Induction Generator Interconnected to the Power Network and Driven by an Electromagnetic Frequency Regulator

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • DAMÁSIO FERNANDES JUNIOR
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • RICARDO FERREIRA PINHEIRO
  • THALES AUGUSTO DE OLIVEIRA RAMOS
  • Data: Sep 30, 2021
    Ata de defesa assinada:


  • Show Abstract
  • The analysis of electricity quality is an essential issue in the integration of distributed energy sources. Due to the increased penetration of such sources connected to the electricity grid, using power converters, new harmonic disturbance limits are regulated by technical standards. . This system is based on a Squirrel Cage Induction Generator (SCIG), and driven by an Electromagnetic Frequency Regulator (EFR). The steady state harmonic model of the REF is developed from the stationary frame, according to the conventional induction machine modeling. Thus, it is possible to analyze the harmonic disturbances occurring in electrical and mechanical quantities due to the EFR armature voltage inverter. The electrical connection between the EFR and the SCIG is non-existent, and the results demonstrate that the system's inherent inertia contributes to the mitigation of the harmonic content on the network side, arising from the converter switching. In addition to steady state results, Total Nominal Distortion (TND), which includes harmonic and interharmonic components, was calculated and performed better compared to the IEEE 1547-2018 standard and real data extracted from a single Generator Powered Induction System (SCIG). Finally, the harmonic performance of the proposed system was evaluated taking into account the impact of the Thevenin equivalent impedance of the electrical network on the Point of Common Coupling (PCC).

19
  • ROGER ROMMEL FERREIRA DE ARAÚJO
  • Boosting Memory Access Locality of the Spectral Element Method with Hilbert Space-Filling Curves

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • JOAO MEDEIROS DE ARAUJO
  • HIROSHI OKUDA
  • Lucia Catabriga
  • LUTZ GROSS
  • Data: Oct 7, 2021


  • Show Abstract
  • The wave equation is pervasive in mathematical physics and engineering, and we need to solve it repeatedly to simulate wave propagations in software. The spectral element method, one of several approaches for the numerical solution of the wave equation, discretizes the underlying domain in a mesh made of elements and nodes, and traverses every element and every node at each time step as it marches the target equation through time. We propose a memory reordering algorithm, meant to be used with the spectral element method, that rearranges mesh-related data to reduce the number of cache misses and boost locality of data reference, thereby improving the execution speed of the mesh traversal process. We devise a spectral element method formulation for 2D waves over unstructured meshes made of triangles, and we pair it to our memory reordering algorithm to construct an acoustic wave propagation simulator. Our experiments show that the reordering technique based on Hilbert space-filling curves performs well in meshes of different granularities, and also when the variation in element sizes is either small or large. In addition, we compare the proposed approach with three other memory reordering schemes, and find that our algorithm runs between 9% and 25% faster than the alternatives we tested. We recommend this memory reordering algorithm to any application that requires successive traversals across domains.

20
  • GUILHERME PENHA DA SILVA JUNIOR
  • Implementation of a Synchronverter Virtual Synchronous Machine for Double Fed Induction Generator Connected to a Microgrid

  • Advisor : LUCIANO SALES BARROS
  • COMMITTEE MEMBERS :
  • DANIEL BARBOSA
  • FLAVIO BEZERRA COSTA
  • FRANCISCO KLEBER DE ARAÚJO LIMA
  • LUCIANO SALES BARROS
  • RODRIGO ANDRADE RAMOS
  • Data: Oct 8, 2021


  • Show Abstract
  • The high integration of Distributed Generation (GD) to the conventional electric system
    brings many challenges to the operating sector, given the growing concerns about the
    reliability of the system and the quality of the energy generation. The DGs have no control
    over the generated energy, although they have very fast power dynamics, with little or no
    inertia. In order to mitigate the impacts caused by the integration between the GD and the
    existing system, it is essential to use the concept of a virtual synchronous machine, whose
    fundament search to emulate the behavior of a real synchronous machine by VSI (Voltage
    Source Inverter) control. In this context, this work proposes the development of a control
    strategy aimed at controlling the DFIG (Doubly Fed Induction Generator) aerogenerator
    so that all necessary requirements can be met to maintain the stability of the grid. The
    purpose will be achieved starting from the assumption that the VSI connected to the grid
    will have similar behavior to a synchronous generator, since the control technique will
    be used Synchronverter. Thus, in addition to greater control over the active and reactive
    powers generated, it is also possible to obtain a contribution with the ancillary services. In
    addition, the DC bus of the back-to-back converter must be connected to a battery bank,
    which will enable greater control over the power dispatch. Therefore, it is possible to
    charge the batteries in the horaires of greater generation and lower energy consumption
    of the grid, as well as to discharge the batteries in the moment of demand of support to
    the frequency of the grid. Preliminary results confirmed the functioning reported in the
    literature, proving the effectiveness of the technique, with potential for improvements that
    the work aims. Finally, with the use of the Synchronverter, it will be possible to operate
    the DFIG autonomously in a microgrid in the occurrence of a Blackout in the system and,
    after ceasing the collapse in the system, synchronize the VSI to the grid without the need
    to use a PLL (Phase Locked Loop).

21
  • AGUINALDO BEZERRA BATISTA JÚNIOR
  • A knowledge graph data-driven approach for analyzing industrial alarm and event records 

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • DIEGO RODRIGO CABRAL SILVA
  • GUSTAVO BEZERRA PAZ LEITAO
  • JUAN MOISES MAURICIO VILLANUEVA
  • PLACIDO ANTONIO DE SOUZA NETO
  • Data: Oct 22, 2021


  • Show Abstract
  • Alarm and event logs make up a voluminous and dormant historical repository of tabular-like data, commonly undervalued or overlooked in manufacturing. Although they are a potentially rich source of relevant information about the monitored plant or process, these records are taken for analysis only as a last resort, mainly due to the difficulties imposed by the large volume and low expressiveness of those databases. Such oversight is no longer acceptable in the contemporary data-oriented scenario, already ubiquitous in several productive sectors and gaining prominence in traditional manufacturing, especially due to the advent of the Industry 4.0 paradigm. Therefore, it is proposed to transpose these bases to a more expressive and flexible representation domain, allowing a more proactive exploration of the episodes reported in the records and, consequently, entailing more agile incident, anomaly, compliance, and performance analysis tasks. For such, from the recognition of an ontology, entities, attributes, and associations virtually immersed in the operational context described in the records are mapped into a Knowledge Graph (KG). The approach uses Exploratory Data Analysis, Natural Language Processing, Network Analysis, Multivariate Analysis, and Composite Indicators techniques to derive a myriad of aspects, properties, and relations from data, which are incorporated as hierarchical, temporal, and similarity relationships (edges) between identified entities (nodes). The visualization of the KG is dynamic and interactive, with different visualization modes and levels of detail. Evaluation scenarios are designed to demonstrate the effectiveness of the approach.


22
  • DIEGO ROCHA LIMA
  • Visual attractiveness in vehicle routing through bi-objective optimization

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • ANAND SUBRAMANIAN
  • BRUNO JEFFERSON DE SOUSA PESSOA
  • DANIEL ALOISE
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUCIANO FERREIRA
  • Data: Dec 3, 2021


  • Show Abstract
  • In this thesis we approach a vehicle routing problem where the route distribution system must consider both its effective cost and its visual attractiveness. Clustering methods are in principle not designed for the Vehicle Routing Problem, but when used, they can provide visually attractive and possibly cost-effective solutions. So, our proposal is to work in an integrated way in a bi-objective method, which are the route cost minimization and the optimization of a grouping criterion, thus making customers better partitioned in different routes. For this we use a multi-objective evolutionary algorithm based on non-dominance ordering, in order to approximate its Pareto Frontier. We show through computational experiments that our model is capable of generating solutions for vehicle routing that have a low cost and at the same time are visually attractive according to the metrics proposed in the literature. Furthermore, the model was tested with a group of instances based on data from a real road network.

23
  • JOSÉ DE ARIMATÉIA PINTO MAGNO
  • ANALYSIS AND DESIGN OF MICROSTRIP ANTENNA ON CERAMIC SUBSTRATES FOR IEEE 802.11ax SYSTEM APPLICATIONS
  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • JOSE PATROCINIO DA SILVA
  • SAMANTA MESQUITA DE HOLANDA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 10, 2021


  • Show Abstract
  • The needs of new wireless communication systems demand that radiant devices are increasingly stable and reliable. In recent years, several proposed solutions are observed in the literature to improve the performance of planar antennas applied in modern wireless communication systems. This work presents the use of ceriferous substrates as a biodegradable solution, of low cost, electrically stable and with many application possibilities to improve the operation of planar antennas in wireless communication systems. Although the use of organic substrates is not new, a variety of manufacturers have lines of boards for planar circuits based on organic compounds. This work proposes in an innovative way the use of ceriferous substrates for the development of miniaturized microstrip antennas. Planar antennas were developed for applications in IEEE 802.11 ax protocol services. Throughout this work, the process of characterizing the proposed material, making the substrates, designing and manufacturing the proposed antennas, numerical analysis and experimental characterization will be presented. Four types of ceriferous substrates based on carnauba wax were selected, and the main characteristics were determined by analyzing the material's electrical properties, X-ray diffraction and thermogravimetry. With results from the characterization of the substrates, the radiating devices were designed and numerically analyzed by the Finite Element method, using the Ansys HFSS® software. The antennas were experimentally characterized in the frequency range from 1GHz to 8.5 GHz, where it was possible to verify that the material used as substrate presented stability and good properties for applications in planar circuits, as in the case of microstrip antennas. There is also the possibility of miniaturization of the radiant elements using carnauba wax as a substrate, when compared to the same structure designed on a standard commercial substrate such as FR4, a miniaturization factor of 44.5% was achieved in the volume of the miniaturized antenna on wax substrate.  

24
  • BRUNO DE MELO PINHEIRO
  • Design of internal antennas and electromagnetic analysis of Osseus, a diagnostic and patient screening device for osteoporosis

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • AGNALDO SOUZA CRUZ
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • FRANCISCO CARLOS GURGEL DA SILVA SEGUNDO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • Data: Dec 10, 2021


  • Show Abstract
  • Osteoporosis is a systemic osteometabolic disease that affects an increasing portion of the Brazilian population, which generates significant costs for the Brazilian Unified Health System (SUS). However, with a previous diagnosis, it is possible to implement preventive measures, which can prevent the occurrence of fractures and reduce SUS costs. In order to enable the necessary exams to identify the pathology and observe its evolution during treatment, maintaining agility and low costs, the development of Osseus was proposed, an instrument that combines techniques and concepts from different areas such as: software engineering, electrical, electronics, computing and biomedical. In addition, the equipment was proposed to be developed at low cost, to be easily accessible to the population and non-invasive, being developed at the Laboratory of Health Innovations and Technologies (LAIS). The latest version of Osseus, version 3.0, had some problems that prevent it from being implemented on an industrial scale. These problems are related to some operational instabilities observed in the part of radio frequency (RF) antennas, which are planar microstrip antennas. Therefore, this work proposes the implementation of improvements in Osseus, aiming to eliminate these instabilities and propose the use of new computational intelligence algorithms, to be used in the equipment. It is hoped, with this, to improve the equipment and provide a low-cost device, helping LAIS fulfill its mission, which is to make science an instrument of love for others.

25
  • ROMÊNIA GURGEL VIEIRA
  • Application of Artificial Intelligence Techniques for Fault Identification in Photovoltaic Modules

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • MARCELO ROBERTO BASTOS GUERRA VALE
  • Data: Dec 14, 2021


  • Show Abstract
  • Photovoltaic solar energy has proven to be a viable alternative that contributes to sustainable development and ensures energy supply around the world. However, the exponential growth of installed capacity in recent years has highlighted the need to ensure the safe operation and reliability of photovoltaic systems. In this context, faults in such systems are a crucial issue, since they can significantly impact the generated power, reduce the useful life, and cause potential risks in operation. Thus, this research applied artificial intelligence techniques to detect and diagnose faults in photovoltaic modules. The faults identified by the proposed methods are short-circuit modules, string disconnection and partial shading. In addition, multilayer perceptron neural network algorithms, probabilistic neural networks, and a neuro-fuzzy method were developed, combining a neural network with fuzzy logic. All trained algorithms were used from simulated and tested experimental data from three different photovoltaic systems. Moreover, training situations in which the dataset is contaminated by random noise were also considered. The results indicated maximum accuracy of 99.1% for the lack of short-circuited modules, 100% for string disconnection and 82.2% for the lack of partial shading. Furthermore, the analyzes allowed to reaffirm the robustness of the multi-layer perceptron network for fault detection in photovoltaic systems, even with the presence of noise in the training data.

26
  • WELLINGTON GUILHERME DA SILVA
  • Miniaturization of Microstrip Antennas for Applications in Cubesats

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO DIONISIO DE ANDRADE
  • LAERCIO MARTINS DE MENDONCA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Dec 15, 2021


  • Show Abstract
  • The objective of this work was to develop a compact microstrip antenna for use in CubeSats, a type of miniaturized satellite mainly used for space exploration and research, used in low earth orbit. The small size of satellites presents a great challenge to the project. One of the main components being a satellite board, an antenna determines the performance of all wireless systems, including: telemetry, tracking, and control (TT&C); downlink of high-speed data; navigation; communications between satellites; radars; and sensors. For the TT&C function, expandable wire antennas are often employed in V-UHF. However, the use of the release mechanism of these antennas can fail and compromise a mission. Therefore, a compact microstrip antenna is desirable. The work presents a literature review covering some concepts about the CubeSat pattern, the fundamentals of antenna theory, such as the main techniques for the miniaturization of antennas, the fundamentals of electrically small antennas, and the main works already developed on the subject. Further investigation was carried out on Wheeler’s method to measure the radiation efficiency of compact antennas, this method is applied to measure the radio efficiency of the built prototype. The work methodology consists of designing, simulating, building, and characterizing a microstrip antenna operating at two frequencies (401,6 MHz and 435,0 MHz) based on the fundamentals of the literature review. These frequencies were chosen to meet the requirements of most CubeSats in use, but in particular, they meet two of the frequencies planned for CONASAT, a project of the Northeast Regional Center (CRN) of the National Institute for Space Research (INPE), located in Natal, in partnership with the Federal University of Rio Grande do Norte (UFRN). The contribution of this work lies in the ability of the developed prototype to operate at two frequencies with a single power supply point, thus reducing the weight, complexity, and risk of failures in the CubeSats communication systems.

27
  • ROANA D' ÁVILA SOUZA MONTEIRO
  • Parameters-Free Non-Iterative Two-terminal Measurements Synchronization and Fault Location Algorithms

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • FELIPE VIGOLVINO LOPES
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MELINDA CESIANARA SILVA DA CRUZ
  • WASHINGTON LUIZ ARAUJO NEVES
  • Data: Dec 16, 2021


  • Show Abstract
  • In this work, angle synchronization method and fault location method were proposed, based on the fundamental frequency phasor approach, independent of the electrical parameters of the transmission line and of iterative processes. In the synchronization algorithm proposed the line capacitive effect is taken into account and only the analysis of steady-state voltage and current phasors is required, eliminating the need for settings based on line electrical parameters. In addition, it identifies angles in any quadrant and is insensitive to operation conditions of the system. Real operating conditions of the Brazilian system are considered to assess the algorithm performance under different scenarios, including light, moderate and heavy line loading cases, and various power factors and line lengths.  The obtained results show that the synchronization proposed solution is reliable, straightforward, accurate, being useful for practical two-terminal phasor-based applications when traditional common time reference sources are not available. The tool developed for fault location requires pre and post-fault current and voltage phasors, work for all types of faults (symmetrical and asymmetrical), and for transposed and untransposed transmission lines. The evaluation of the fault location algorithms is performed through fault simulations by the ATPDraw software. The obtained results prove the efficiency of the method in finding fault location with good precision.

2020
Dissertations
1
  • JURGEN KLINSMANN AZEVEDO NOGUEIRA
  •  Analysis of Planar Antennas for Medical Applications at 435 MHz, 915 MHz and 2.45 GHz ISM Bands

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • HERTZ WILTON DE CASTRO LINS
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Jan 10, 2020


  • Show Abstract
  • Wireless devices are presented in the latest research works as alternatives for monitoring several medical parameters, with applications in the frequency bands designated for Medical Device Radiocommunications Service - MedRadio (401 - 405 MHz), Medical Implant Communication Services - MICS (402 - 405 MHz) and Industrial, Scientific and Medical - ISM (433 - 435.8 MHz; 2.4 - 2.5 GHz). This master thesis presents a frequency response analysis of planar microstrip antennas with medical applications in the ISM band for the three frequency bands (433 - 435.8 MHz; 902 - 928 MHz; 2.4 - 2.5 GHz). Three rectangular slotted antennas are designed with the slots placed near the edges of the patch. Simulation results were obtained by Ansoft HFSS software for resonance frequency, bandwidth and reflection coefficient. Measurements were performed with solid samples of pork. The simulated and measured results showed excellent agreement.

2
  • CARLA DOS SANTOS SANTANA
  • Workload scheduling analysis in geophysical numerical methods

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • Angelo Amâncio Duarte
  • CALEBE DE PAULA BIANCHINI
  • HERVÉ CHAURIS
  • SAMUEL XAVIER DE SOUZA
  • TIAGO TAVARES LEITE BARROS
  • Data: Jan 13, 2020


  • Show Abstract
  • The tasks organization among computational nodes affects the performance of the program. In computationally expensive applications such as geophysical problems, the impact is more significant. The imbalance caused by inefficient task scheduling can generate an application non-scalable. Therefore this work investigates the workload scheduling in geophysical methods.

     Three types of workload scheduling will be compared: centralized dynamic (CD), decentralized static (DS), and decentralized dynamic (DD).  The CD was implemented with the technique master-slave, where the master node is responsible for the distribution of the tasks to other nodes called slaves. The DS with an equal division of tasks. The DD implements the work-stealing method proposed by Assis et al. 2019, where an idle node can steal the tasks of an overloaded node.

    The principal geophysics method used was Full waveform inversion (FWI) 2D with the acoustic wave. To analyze the performance of workload scheduling methods, we employ a synthetic velocity model and present speedup, efficiency, and load distribution plots generated with different model sizes and different quantity of nodes. The FWI code and the workload scheduling methods were implemented in C to distributed memory parallelization and using the message passing interface (MPI) library.

    With the results of the workload scheduling methods in FWI, it was applied the work-stealing (because this technique presented the more effective performance) in another geophysics problem: Least-squares migration (LSM).  We used the LSM with DS implemented by Chauris et al. 2017 to compare with the LSM with work-stealing. The LSM code and DS used in this problem were implemented in Fortran and the work-stealing in C. The communication between the nodes was implemented using MPI.  To analyze the performance of workload scheduling methods in LSM, we used the marmousi velocity model.

3
  • JOÃO BATISTA FERNANDES
  • Auto-tuning of load scheduling of granularity for multi-core processors applied to reverse time migration

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • HUGO ALEXANDRE DANTAS DO NASCIMENTO
  • IDALMIS MILIAN SARDINA MARTINS
  • SAMUEL XAVIER DE SOUZA
  • TIAGO TAVARES LEITE BARROS
  • Data: Jan 14, 2020


  • Show Abstract
  • Reverse time migration (RTM) is an algorithm widely used in the oil and gas industry to process seismic data. It is a computationally intensive task that suits well in parallel computers. Because of it being massive and regular, this type of task is often equally and statically distributed among the available parallel workers. However, this strategy is often not optimal. When the workers are heterogeneous, and even when most have similar processing power, many of them might still have to wait idly for the slower workers. In this paper, we show that even small performance differences between homogeneous cores can considerably affect the overall performance of a 3D RTM application. We show that dynamic load distribution has a significant advantage over the conventional static distribution, and others defaults OpenMP scheduling, auto and guided. However, the granularity of the dynamically distributed chunks of work plays a key role in harvesting this advantage. In order to find the optimal granularity, we propose a coupled simulated annealing (CSA) based auto-tuning strategy that adjusts the chunk size of work that OpenMP parallel loops assign dynamically to worker threads during the initialization of a 3D RTM application. Experiments performed on computational systems with different processor and RAM specifications and for different sizes of input show that the proposed method is consistently better than the default OpenMP loop schedulers.

4
  • Vitor Hugo Mickus Rodrigues
  • GPU Support for Automatic Generation of Finite-Differences Stencil Kernels

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • LUCAS COSTA PEREIRA CAVALCANTE
  • Pedro da Silva Peixoto
  • CALEBE DE PAULA BIANCHINI
  • Gerard John Gorman
  • Data: Jan 16, 2020


  • Show Abstract
  • The growth of data to be processed in the Oil & Gas industry matches the requirements imposed by evolving algorithms based on stencil computations, such as Full Waveform Inversion and Reverse Time Migration. Graphical processing units (GPUs) are an attractive architectural target for stencil computations because of its high degree of data parallelism. However, the rapid architectural and technological progression makes it difficult for even the most proficient programmers to remain up-to-date with the technological advances at a micro-architectural level. In this work, we present an extension for an open source compiler designed to produce highly optimized finite difference kernels for use in inversion methods named Devito c . We embed it with the Oxford Parallel Domain Specific Language (OP-DSL) in order to enable automatic code generation for GPU architectures from a high-level representation. We aim to enable users coding in a symbolic representation level to effortlessly get their implementations leveraged by the processing capacities of GPU architectures. The implemented backend is evaluated on a NVIDIA R GTX Titan Z, and on a NVIDIA R Tesla V100. in terms of operational intensity through the roofline model. Experimented with a 3D acoustic isotropic wave propagation stencil kernels for varying space-order discretization levels. It achieves approximately 63% of V100’s peak performance and 24% of Titan Z’s peak performance for stencil kernels over grids with 256 3 points. This study reveals that improving memory usage should be the most efficient strategy for leveraging the performance of the implemented solution on the evaluated architectures.

5
  • GISLIANY LILLIAN ALVES DE OLIVEIRA
  • A data-driven approach for the generation of a liveability index based on the UBER API

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUCIANA CONCEICAO DE LIMA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • PATRICIA TAKAKO ENDO
  • Data: Jan 24, 2020


  • Show Abstract
  • One of the global dilemmas concerns the accelerated urban transition in the last decades. Therefore, promoting sustainable urban development to accommodate population growth is extremely important. Under those circumstances, the concept of liveability arises, being defined as a principle that combines economic, social and environmental attributes to promote quality of life and human well-being, and it is widely discussed in the New Urban Agenda (NUA) adopted by the United Nations in 2016. NUA defines policies to promote the consolidation of  Sustainable Development Goals (SDGs), with its Goal 11 focusing on a pro-urban future. To supervise SDGs implementation and ensure that these goals are met, it is recommended the use of indicators and the liveability concept can then be associated with an indicator for this purpose. However, there are known issues related to data unavailability, poor quality and aggregation, that make the SDGs monitoring difficult. Considering the described scenario, this work proposes a liveability indicator that combines traditional census data with alternative data sources, such as data  from Uber, a popular ride-sharing service. Assuming that Uber service behavior can act as a proxy to liveability, a data science approach based on exploratory and spatial data analysis was conducted using Uber’s Estimated Time of Arrival (ETA) data sourced for the Brazilian city of Natal (RN). This approach aims to build a composite indicator which can portray at some level the liveability for that city. The proposed methodology was applied at two different spatial aggregation levels: neighborhoods and Human Development Unities (HDUs). Results showed how the Uber service oscillates spatially and how it reacts to weather variations, festivals, and other events, as well as its relations with existing social and infrastructural indicators. It was also observed that different spatial aggregation levels affect the Uber ETA and its relations with socioeconomic variables. Finally, the proposed indicator was created at HDU scale to be applied in sustainable development monitoring. Furthermore, it was concluded that West and North administrative regions of Natal predominantly have localities with the worst liveability indicators. 




6
  • TALINE DOS SANTOS NÓBREGA
  • Statistical analysis of electroencephalographic data in human applications

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDRÉ MENDES CAVALCANTE
  • EDGARD MORYA
  • HELIANA BEZERRA SOARES
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jan 31, 2020


  • Show Abstract
  • The motor activities of the human body, as well as those related to decision making and emotional and psychic issues, can be understood through the analysis of electrical signals from the brain, also known as electroencephalogram (EEG) signals. The study and application of electroencephalographic data has been growing within the scientific community. It is known that the use of these signals forms the basis of the development of the Computer Brain Interface (ICC), and that these represent the future of assistive technologies, especially those aimed at people who do not have motor control. However, the extraction of characteristics and patterns of these signals is still a complex process. Surveys involving ICC and EEG signals usually implement event related potentials (ERP) analyzes; being the main ones: the static potentials evoked visually (SSVEP) and the potential P300. In general, they are responses to external stimuli (visual, auditory, tactile), and are widely used to recognize patterns in EEG signals associated with changes in brain activity. The purpose of this paper is to analyze the signs of the neural activity of individuals who are exposed to external stimuli using the identification of potential SSVEP and P300. The project uses a low-cost, non-invasive EEG signal sensor with wireless, wireless technology. It is expected to extract EEG data to the point of making possible the correlation of these with characteristics that can be applied in control tools.

7
  • IAGO DIÓGENES DO RÊGO
  • FFR-based ICIC powered by Q-Learning as a solution for interference in high user density areas (hotspots)

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • ANDRÉ MENDES CAVALCANTE
  • VALDEMIR PRAXEDES DA SILVA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jan 31, 2020


  • Show Abstract
  • This work aims to explore interference coordination techniques (ICIC) based on fractional frequency reuse (FFR) as a solution for interference in a multicellular scenario. The system presents a dynamic variation on the density of its users. Therefore, the Q-Learning algorithm performs the dynamic configuration of the ICIC parameters. The first chapter discusses the problem of high user density and its consequences. The following chapter presents some classic solutions, leading to the introduction of Fractional Frequency Reuse (FFR) and existing FFR techniques. Prior results are presented for performance evaluation. These also serve to guide the choice of relevant parameters and to highlight the impact of high user density. The final chapters present the results regarding the use of Q-Learning in the dynamic scenario.

8
  • JOSÉ MARTINS DE CASTRO NETO
  • Coexistence Solutions for LTE and Wi-Fi Systems in Multicell Deployments

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • LEONARDO AGUAYO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Aug 10, 2020


  • Show Abstract
  • The growth of mobile internet access from fourth generation (4G) devices, combined with increasing usage of smartphones, the upcoming fifth generation (5G) and massive usage of multimedia services, make the demand for mobile traffic reach high levels and the need for bandwidth grows. However, the electromagnetic spectrum utilized by these applications is limited, creating scarcity in the face of demand, besides the high costs and bureaucracy for granting new bands. To overcome this problem, one of the solutions is to leverage the unlicensed spectrum, for it is free of charges, presents some of its portions with bandwidth higher than the licensed spectrum, and portions with underused profile, indicating less probability of interference between technologies. In this context rises the LTE-U and LTE-LAA technologies with modifications in the medium access mechanism of LTE for leveraging the unlicensed spectrum in the Industrial, Scientific and Medical (ISM) 5 GHz band. These technologies must coexist with the most successful and consolidated technology already using this portion of the spectrum, the Wi-Fi. However, each technology implements its access mechanism, then studies must be done to point out impacts that each of these technologies has when coexist. Besides the coexistence study, the application of machine learning techniques to automatically adjust the medium access parameters, controlling the generated impact of one technology into another must be realized.   Studies in such a scenario and with single-cell environments have already been explored in literature, remaining the challenge of new solutions targeting multi-cell environments. For all it has been exposed, this work has the following goals: (1) The coexistence study of LTE-U and Wi-Fi technologies in a multi-cell scenario, with co-channel and inter-RAT (same technology) interference; (2) The application of machine learning algorithms (reinforcement learning) to adjust the parameters targeting optimizing the medium access for one, or both technologies, and consequently reach improvements in the coexistence measured in the form of data rates and decreasing packet losses. 

9
  • NILSON HENRIQUE DE OLIVEIRA CUNHA
  • Metamaterial unit cell analysis using EBG substrates for integrated circuit applications

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • FRANCISCO DAS CHAGAS BARBOSA DE SENA
  • Data: Aug 26, 2020


  • Show Abstract
  • With the growth in communications and the intense study of how to transmit and receive electromagnetic signals more efficiently, printed circuits have gained prominence on the world scene. The flat profile, easy construction and easy integration with other nowadays systems are attractive of these circuits that are present in almost all current devices. However, it is known that these types of elements have several disadvantages such as relative low gain, generally narrow bandwidth and low efficiency. To solve these various problems, elements that work in sets are often added, such as filters and Substrate Integrated Waveguide (SIW), but it is not always possible to apply these elements due to the physical limitations of the desired system. An alternative to work around these limitations is the application of structures with prohibited bands of electromagnetic wave propagation called EBGs (Electromagnetic Band Gap), another alternative is the application of artificial structures called metamaterials (MTMs). However depending on the format, distribution and periodicity, quasi-periodicity or non-periodicity of these techniques it is possible to obtain different results, such as increase in gain, bandwidth, impedance matching, efficiency increase, among many other parameters reported in the literature. In this context, aiming to merge the techniques mentioned above, we intend to carry out a study, from the characterization of a simple MTM-EBG cell to its application in circuits such as antennas, filters and printed lines, so as to prove the usefulness and scientific importance of these techniques for applications in current systems.

10
  • EMERSON VILAR DE OLIVEIRA
  • Performance Evaluation of LSTM Network-Based Method for Failt Classification in a Level Control Process

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • CLAUBER GOMES BEZERRA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Aug 28, 2020


  • Show Abstract
  • Due to the increasing demands in the operation monitoring of industrial plants, methodologies for fault detect and diagnose in the operation of these processes are gaining more and more importance, because they can contribute to more assertive and even predictive repairs in the components that generated such disturbances to the proper functioning of the system. With the growth of data-oriented approaches, Artificial Neural Networks have become considerable allies in solving these problems, and Recurrent Neural Networks, in particular, have gained strength due to their affinity in dealing with series that have temporal links between their samples, which is the case of industrial process variables monitoring. Due to this relevance, this dissertation analyzes the performance of Long Short-Term Memory (LSTM) recursive neural network for the detection and classification of faults in a pilot-scaled level control process. For the performance evaluation, a methodology based on Monte Carlo statistical tests was used, in which the influence of the LSTM network hyperparameters, such as number of layers and size of the input and regressors, was analyzed. The accuracy was the metric chosen to quantify the fault classification performance. The data set obtained from the operation of the pilot plant contained 23 situations of disturbances in this process, which resulted from disturbances applied to components such as sensor, valves and the water tank itself. The adopted methodology proved to be quite efficient to analyze both the performance and the robustness of these neural networks for the fault classification activity, in addition to indicating the best network architecture configurations.

11
  • Júlio Gustavo Soares Firmo da Costa
  • Metadata Interpretation Driven Development: promoting software development dissociated from the business domain

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • GIVANALDO ROCHA DE SOUZA
  • LUIZ MARCOS GARCIA GONCALVES
  • NELIO ALESSANDRO AZEVEDO CACHO
  • SAMUEL XAVIER DE SOUZA
  • Data: Sep 2, 2020


  • Show Abstract
  • Separation of Concerns is a topic widely addressed in academia and industry. Finding ways to separate software concerns is the basis for reducing software system development costs. Although the software construction research field with the objective of obtaining a high degree of reuse is considered a relatively mature field - based on the abstraction of components - relevant changes in the software services scenario are occurring and open opportunities for new approaches related to question. The emergence of new software architectures, such as serverless computing, in the context of cloud computing, reinforces the need to think software construction possibilities based on this new scenario. It is in this context that Metadata Interpretation Driven Development (MIDD) is presented, a methodology whose purpose is to increase the degree of reuse of software artefacts that are built from their use. Its particularity, in relation to the methodologies currently employed, is that it requires a complete dissociation between the application code and the representation of the business domain, commonly put in that. That is, the application must be able to interpret the concepts of the business domain, and not implement them. As we will see, doing that, the same instances of software built with MIDD may provide software service to demands for a distinct business domain at the same time, without changing its code.

12
  • JOSÉ MARCOS LEAL BARBOSA FILHO
  • Wireless Wideband Channel Sounding: Techniques, Simulation and Data Post-processing

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • LEONARDO HENRIQUE GONSIOROSKI FURTADO DA SILVA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Sep 11, 2020


  • Show Abstract
  • In recent years, the demand for high data rates in wireless communications has increased. The Enhanced Mobile Broadband (eMBB), one of the use cases of fifth generation of mobile communications systems (5G), requests 20 Gbps of minimum peak data throughput using carrier aggregation technique to achieve ultra-widebands. However, wideband and ultra-wideband signals are more susceptible to time and frequency spread degradation due to signal propagation over multiple paths and relative movement between transceivers, respectively. In this context, the channel sounding is of great relevance, since it allows to estimate the characteristics of the transmission medium, enabling the conception of solutions to combat the performance degradation imposed by the communication channel. From this perspective, this work develops a research on the main wideband channel sounding techniques, taking as main objective the conception in software of a channel sounding simulator and a post-processing and analysis tool for wireless wideband channel characterization. In addition, a comparative analysis of the direct cross-correlated soundings is performed, using 6 different sequences as sounding signal. Among them are the sequences PN, Frank-Zadoff-Chu and Golay.

13
  • FREDERICO AUGUSTO FERNANDES SILVEIRA
  • Smart-IoT: a DDoS protection system for the Internet of Things

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • EDMAR CANDEIA GURJÃO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RAMON DOS REIS FONTES
  • Data: Oct 20, 2020


  • Show Abstract
  • The increase in the number of networked devices in the context of the Internet of Things (IoT) has driven the number of Distributed Denial of Service (DDoS) attacks in recent years. This threat takes advantage of the security limitations of these devices and their geographic locations to leverage the impact of the attacks. Developing mechanisms to detect and mitigate DDoS attacks in this new paradigm is a current challenge in network security. This work proposes a defense mechanism integrated into the IoT network controller that uses Machine Learning (AM) techniques to detect these attacks and the flexibility of Software-Defined Networks (SDN) for their mitigation. The proposed system uses random samples to perform network traffic classification and the OpenFlow (OF) protocol to apply real-time mitigation measures.  The solution was tested with four recent datasets in a controlled laboratory environment, showing to detect and mitigate DDoS attacks, with a high hit rate and low false alarm rate.

14
  • CAIO JOSÉ BORBA VILAR GUIMARÃES
  • Embedded Artificial Neural Networks Optimized for Low-cost and Low-Size-Memory Devices

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • BRAD MCDANEL
  • EDGARD DE FARIA CORREA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Oct 22, 2020


  • Show Abstract
  • Artificial Neural Networks (ANNs) are bio-inspired systems with a high level of parallelization and almost infinite applications. However, due to the associated high computational power requirements, most application demands powerful processing characteristics and consequently, high-costs and not-so-small form-factors. This work presents an implementation of a Multilayer Perceptrons (MLPs) for 8-bit microcontrollers in two different scenarios, embedded training, and inference. Analysis of training convergence, inference time duration, and program code occupation into the internal memories and a technique to optimize this implementation to fit bigger MLP architectures. The aim of this work is to provide an overview of the feasibility of ANNs on these low-cost, low-size-memory devices, known as microcontrollers

15
  • DENIS RICARDO DA SILVA MEDEIROS
  • Proposal of Embedded Standalone and Distributed Genetic Algorithms for Low-Power, Low-Cost and Low-Size-Memory Devices

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • MARCELO AUGUSTO COSTA FERNANDES
  • PATRICIA DELLA MÉA PLENTZ
  • Data: Nov 5, 2020


  • Show Abstract
  • This work proposes implementations of genetic algorithms targeting low-power, low-cost, and low-size-memory devices in two variants: a standalone version, to be used in one single device, and a distributed version, to be used in multiple devices simultaneously. The motivation is to adapt and optimize this important artificial intelligence (AI) technique so that it can be used in numerous applications where traditionally it was not feasible to be utilized, such as in microcontrollers. An investigation about how to optimize each separated segment of the algorithm is done and extensive details about both implementations are provided, including their source codes. Moreover, various experiments and simulations for multiple scenarios were done to validate their correct operation using Hardware-In-Loop technique, as well as to find out limitations for the algorithm parameters. The standalone implementation is compared to other work in the literature and it performs faster and using fewer resources. For the distributed version, an important analysis was done to verify that it can be faster than the standalone version but also more power-efficient when reducing the clock speed and voltage of those devices. Finally, this investigation could determine what is the threshold from where the distributed version, even with a high overhead due communication between the devices, become either faster or more power-efficient than the standalone one.

16
  • ANDREZA CRYSTINE CARVALHO DE OLIVEIRA
  • Computation of Robust Controlled Invariant Sets with Fixed Complexity Using Bilinear Optimization

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • AMANDA DANIELLE OLIVEIRA DA SILVA DANTAS
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • CARLOS EDUARDO TRABUCO DOREA
  • JOSÉ MÁRIO ARAÚJO
  • Data: Nov 6, 2020


  • Show Abstract
  • In this work, a methodology for the computation of robust controlled invariant polyhedra of fixed complexity, based on bilinear optimization, is proposed for discrete-time linear systems, subject to constraints on the states and control inputs and to bounded disturbances. In many real-life applications, certain variables in a system must comply with certain constraints. In general, these constraints are specified by linear inequalities that define limited and closed polyhedral sets. A set is robust controlled invariant if any state trajectory starting in this set can be maintained within it through a suitable control input, in spite of the disturbances. Thus, the calculation of a controlled invariant set is an important step in solving control problems under constraints. Conventional methods for robust invariant polyhedra computation can result in high complexity sets, defined by a large number of vertices. The methodology proposed in this work has bilinear invariance conditions and polyhedra represented by vertices, whose quantity is fixed in advance. The aim is also to maximize the volume of the robust controlled invariant polyhedra. Through numerical examples, the methodology is able to compute polyhedra with larger volumes than those obtained by recent methods which also seek for reduced complexity sets. In addition, a methodology is numerically efficient, applicable to larger systems than those treated by the methods available in the literature.

17
  • JOSÉ RAIMUNDO DANTAS NETO
  • Control Strategy Applied For Distributed Generatior Systems Through Virtual Synchronous Machine Concept.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ALEXANDRE CUNHA OLIVEIRA
  • ALLAN DE MEDEIROS MARTINS
  • MÁRIO LÚCIO DA SILVA MARTINS
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Dec 17, 2020


  • Show Abstract
  • The increasing of Distributed Generation (DG) based on renewable energy sources (RES) has contributed to the reduction of several environmental, economic and social impacts caused by the burning of fossil fuels in the conventional generation system. However, the massive increase in the energy production based on FERs, also causes undesirable impacts, such as the decrease of the grid inertia, voltage oscillations and stability margins reduction. In addition, the Electrical Power System (EPS) has changed its configuration and the microgrid concept has gained interest in recent years. In this approach, more efficient and reliable control systems are required for proper EPS operation. Thereby, DG control strategies have been developed aiming, not only to provide the power from primary sources, but also provide voltage and frequency support to the power grid, increasing the stability margins and guaranteeing the energy quality. Thus, this work proposes a control system based on Virtual Synchronous Generator (VSG) approach, aiming to contribute to the stability of the electrical network, providing voltage support by regulating the power flow, using the P/ω and Q/V droop control technique. Frequency support is obtained by introducing a virtual inertia in the DG. The virtual inertia is emulated by means of transport delay techniques applied in the power loop. Unlike most works that use the VSG approach, a smooth start up scheme is developed, using the voltage vector estimation of the electrical grid, made by an SRF-PLL (Synchronous Reference Frame Phase Locked Loop). Simulation results are presented to validate the proposed method.

18
  • SILVAN FERREIRA DA SILVA JÚNIOR
  • Evaluating Human-Machine Translation with Attention Mechanisms for Industry 4.0 Environment SQL-Based Systems

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • FRANCISCO DE ASSIS BRITO FILHO
  • GUSTAVO BEZERRA PAZ LEITAO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • Data: Dec 18, 2020


  • Show Abstract
  • The use of relational databases is increasingly present in the industry. Applications in medicine, IoT and Industry 4.0 are examples of this. Despite the great capacity and efficiency in data storage and retrieval, this type of database requires technical knowledge in specific query languages to access this information, which distances these types of applications from the non-specialized public. In this work, we propose an application of recent models in natural language processing that uses mechanisms to translate natural language into English into SQL applied to a database that stores sensor data, focusing on the concept of Industry 4.0. Paired examples of natural language phrases were generated with their corresponding SQL query to be used for training and validation. The model was agnostic in relation to the database schema, so that it only handles the input and output sequences regardless of the database structure. The data comes from historians of the typical process used in industrial settings. When training the deep neural network, we obtained a language model with an accuracy of approximately 99 \% in the validation set.

19
  • GABRIEL PEREIRA DE OLIVEIRA
  • Cooperative Control Applied for Power Flow Management of a DC Migrogrid Integrated with Energy Storage System

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • EUZELI CIPRIANO DOS SANTOS JUNIOR
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Dec 18, 2020


  • Show Abstract
  • The growing energy demand and the increasing social/political concern for the environment has driven the insertion of renewable energy sources (RESs) in the power system. These sourcers are inserted as distributed generation (DGs) systems in the new matrix energy model organized by microgrids (MGs). RESs are dependent on meteorological conditions which make it intermittent and stochastic. To provide the energy balance of these microgrids, it is necessary to integrate energy storage systems (ESSs). Therefore, this work proposes a cooperative control strategy to regulate the power flow of a DC MG with an interconnected ESS. The proposed strategy coordinates the voltage control of the DC bus by Interlink CC (ILC) and by ESS to provide power smoothing. To decouple the control loops from the bus, a Gaussian inference function is used based on the information of the voltage deviation on the DC bus. The proposed technique is validated through digital simulations.

20
  • JOÃO GUILHERME DOMINGOS DE OLIVEIRA
  • Analysis of Planar Structures for Applications in Sensing Systems
  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • VALDEMIR PRAXEDES DA SILVA NETO
  • ADAILDO GOMES D ASSUNCAO
  • FRED SIZENANDO ROSSITER PINHEIRO
  • ROSSANA MORENO SANTA CRUZ
  • Data: Dec 23, 2020


  • Show Abstract
  • Two sensors for the characterization of the dielectric constant of different types of materials have been implemented and one of them applied in the determination of the soil water content (θ), while the other is a bio inspired antenna based on the Shiso leaf. The proposed sensors consist of in: The shape of the antenna patch is inspired by the Shiso leaf, whose scientific name is Perilla Frutescens. A complementary interdigital capacitor (CIDC) is inserted into the geometry; A microstrip antenna with a circular patch in a container printed on ABS filament, based on the complementary split-ring resonator (CSRR) structure. The operating principle is based on the displacement of the element’s resonance frequencies when the relative permittivity of the material under test (MUT) is changed. Several simulations were performed, with the data obtained, two empirical models are proposed. To validate its effectiveness, measurements were made with dielectric substrates that have the dielectric constant known in the literature. The second sensor can be applied to different types of materials, in this work it was used to determine the percentage of water contained in different types of soils. The prototypes were built and the results obtained in the measurements were compared with the results of other studies, thus validating the effectiveness of the proposed sensors.

21
  • JOSE GARIBALDI DUARTE JUNIOR
  • Study of a Reconfiguration Methodology Applied to the Development of Adjustable Microwave Planar Filters
  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • FRANCISCO DE ASSIS BRITO FILHO
  • MURILO ARAUJO ROMERO
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 28, 2020


  • Show Abstract
  • Filters play an important role in many radio frequency (RF) and microwave applications. They are used to separate or combine different frequency bands. The electromagnetic spectrum is limited and needs to be shared, so the filters have the function of limiting and / or selecting the microwave / RF signals within the assigned spectral limits. The reconfigurable, or tunable, microwave filters have attracted a lot of attention from researchers and designers due to their emerging characteristics of improving spectral capacity and performance in current and new communication systems. This work presents a study about reconfigurable microwave planar filters. A reconfiguration methodology based on the use of semiconductor devices of the varactor diode type is proposed in order to allow the adjustment of impedances along the geometry of the filter resonator, and thus, configure the frequency response of the filtering device. The designs of three reconfigurable devices are presented, being applicable to the communication standards 5G NR sub-6 GHz, with the model 01 being a band-reject filter, and the models 02 and 03, band-pass filters. Analyzes of the equivalent circuits of the filters are developed in order to establish an understanding of their respective performances depending on the geometry and the adjustment device. The initial analyzes and simulations were performed using the equivalent circuit method and the finite element method using the Ansys HFSS software, and the equivalent model of the varactor diode was also used according to its datasheet. Preliminary results are presented, which include the response obtained through simulation and measurement of the models without the use of varactors and results with the application of the reconfiguration methodology based on the varactors. Finally, the next fundamental steps for the continuation of the research are pointed out.

Thesis
1
  • RAMON AUGUSTO SOUSA LINS
  • Deep reinforcement learning one new perspective on the k-server problem

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • GUILHERME DE ALENCAR BARRETO
  • JORGE DANTAS DE MELO
  • MARCELO AUGUSTO COSTA FERNANDES
  • SAMUEL XAVIER DE SOUZA
  • Data: Jan 28, 2020


  • Show Abstract
  • The k-server problem in a weighted graph (or metric space) is defined by the need to efficiently move k servers to fulfill a sequence of requests that arise online at each graph node. This is perhaps the most influential online computation problem whose solution remains open, serving as an abstraction for a variety of applications, as buying and selling of currencies, reassign processes in a parallel processing for load balancing, online transportation service, probe management of oil production rigs, among others. Its conceptual simplicity contrasts with its computational complexity that grows exponentially with the increasing number of nodes and servers. Prior to this work, the Q-learning algorithm was used to solve small instances of the k-server problem. The solution was restricted to small dimensions of the problem because its storage structure grows exponentially with the increase in the number of nodes and servers. This problem, known as the curse of dimensionality, makes the algorithm inefficient or even impossible to execute for certain instances of the problem. To handle with larger dimensions, Q-learning together with the greedy algorithm were applied to a small number of nodes separated into different clusters (hierarchical approach). The local policy obtained from each cluster, together with
    greedy policy, were used to form a global policy satisfactorily addressing large instances of the problem. The results were compared to important algorithms in the literature, as the Work function, Harmonic and greedy. The solutions proposed so far emphasize the increase in the number of nodes, but if we analyze the growth of the storage structure defined by Cn;k ' O(nk) It can be seen that the increase in the number of servers can be quickly limited by the problem of the curse of dimensionality. To circumvent this barrier, the k-server problem was modeled as a deep reinforcement learning task whose state-action value function was defined by a multilayer perceptron neural network capable of extracting environmental information from images that encode the dynamics of the problem. The applicability of the proposed algorithm was illustrated in a case study in which different problem configurations were considered. The behavior of the agents was analyzed during the training phase and their performance was evaluated from performance tests that quantified the quality of the displacement policies of the servers generated. The results provide a promising insight into its use as an alternative solution to the k-servers problem.

2
  • WILLIANS RIBEIRO MENDES
  • Remote sensing data integration applied to variable rate irrigation systems by using fuzzy decision support systems

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • PAULO ESTEVÃO CRUVINEL
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSENALDE BARBOSA DE OLIVEIRA
  • RAFAEL VIEIRA DE SOUSA
  • Data: Feb 7, 2020


  • Show Abstract
  • Freshwater is a scarce resource, and nowadays it is under unprecedented focus due to concerns about the sustainability of natural ecosystems and because of the high agricultural demand, which needs to feed a growing global population. These concerns make freshwater a necessary natural resource for everyone. All these issues lead us to want to manage this asset more efficiently, thus generating an increase in the demand for more intelligent, more automated and more accurate systems. These needs are the driving force behind the development and implementation of new technologies for more rational use, allowing farmers to improve when and where irrigation is applied, seeking to increase food production. In this manner, this work presents a new proposal for an intelligent variable rate irrigation system application in order to achieve that goal. It will be a site-specific irrigation management tool; in other words, a system that should assist in decisions about applying water quantity to delimited zones. We expect a higher yield from crop productivity and greater efficiency in water use. To be successful, the system has an artificial intelligence approach to automatically create optimal control maps for a center pivot irrigation system. At the heart of this system there will be the fuzzy logic, which will be able to set the reference values for the rotating speed controllers and individual opening of each central pivot sprinkler valve. The proposed system will be based on the decision making (whether applying more or less water) and will use remote sensing data, so we expect the smart irrigation system to describe the spatial variability of the crop efficiently. The results point out that the edaphoclimatic variables, when well combined with fuzzy logic, can solve uncertainties and non-linearities of an irrigation system and define a control model for high precision irrigation. However, it will not always be possible to reduce water consumption, but this technology has many uses to increase farm profitability.

3
  • ROBERTO DOUGLAS DA COSTA
  • Classification of system-based intelligent learning styles: a case study in technology-mediated education

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ALINE DE PINHO DIAS
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • ELOIZA DA SILVA GOMES OLIVEIRA
  • GUSTAVO FONTOURA DE SOUZA
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Feb 14, 2020


  • Show Abstract
  • With the growth of distance education (EAD) in Brazil in its levels of education, be it medium, technical or superior and the increase in the offer of online courses made available through the Virtual Learning Environments (AVA), there is a concern with the development Of this student during the course and their learning. In order to associate the resources and activities offered in AVA with the Learning Styles classes, this work proposes to create an algorithm that can identify the behavior patterns of the EAD students through the use of tools available in the AVA and associates them with a classification of Learning Styles in order to assist the teacher in the preparation of his / her lesson plans, suggesting resources and evaluation activities arranged in the AVA that will favor the learning of its students according to the Learning Style characteristic of each one of them.

4
  • JOSÉ CLÁUDIO VIEIRA E SILVA JUNIOR
  • Hardware Strategies Applied to the Latency Reduction on Tactile Internet

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • LUCAS M. OLIVEIRA
  • DENNIS BARRIOS ARANIBAR
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Feb 28, 2020


  • Show Abstract
  • This work proposes to present hardware strategies applied to reduce latency in the tactile internet. The motivation is to study the challenges contained in the development of the hardware associated with the tactile devices, especially issues related to the round trip latency limit of the system components. As is known, for a tactile internet environment to work desirably, it is necessary to respect a minimum limit of round trip latency. Since some tactile applications allow some human senses to interact with the machines remotely, this means that, almost always, the minimum limit of round trip latency has a time delay in the range of milliseconds. Thus, it is clear that there is a demand for tactile devices that are quite fast. In this context, three hardware proposals are presented that have the main objective to reduce the total latency produced by this type of device. The first strategy proposed for the development of hardware is to use reconfigurable computing (on FPGA) to minimize the execution time of the algorithms associated with the device. The second hardware proposal also makes use of reconfigurable computing (on FPGA). However, the hardware is designed using another type of numerical representation. Finally, the third proposal presents a tactile glove model implemented using a variety of micro processed system. Results associated with the three proposals are presented and show the viability of the strategies, presenting better performance concerning the works that were compared.

5
  • PEDRO THIAGO VALERIO DE SOUZA
  • Spectral Sensing and Signal Detection in MIMO Systems with Impulsive Noise and Multiple Path Fading
  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Waslon Terllizzie Araujo Lopes.
  • ALUISIO IGOR REGO FONTES
  • GUILHERME DE ALENCAR BARRETO
  • Data: Mar 9, 2020


  • Show Abstract
  • In mobile systems, information signals must be transmitted with high rates of data transmission and with high reliability. One of the possible solutions to achieve these desirable requirements is the use of systems with multiple transmitting and/or receiving antennas, featuring a MIMO system (Multiple Input-Multiple Output). However, signal processing techniques in MIMO systems depend on the Gaussianity of the transmission channel, decreasing their efficiency in non-Gaussian communication scenarios. To goal a robustness of this transmission technique, it will become imperative or to study this transmission technique in scenarios in which the channel is not exhibited by Gaussianity. In this work, a new signal detection technique in MIMO systems is proposed in scenarios characterized by non-Gaussian noise. A proposed reception technique is called Maximal Correntropy Detector (MCD) and it has been experimentally proven to treat a generalization of the MLD detector (Maximum Likelihood Detector) using the use of the correntropy complex. The MCD detector is analyzed on Gaussian and non-Gaussian channels and its performance is superior to classic detectors, without a significant increase in computational complexity. Together, this work also presents a new method of spectral sensing suitable for detecting signals that show non-linear phase variations over time. The proposed method is based on the use of theory of cyclostationary signals in waiting time, or which transformation employs signals to be a sensor in order to mitigate or effect non-linear variation of the phase. A proposed architecture is evaluated without a BPSK signal sensor and is compared to a temporal cyclostationary sensing technique. The results of the simulation tested prove the efficiency of the architecture proposal, presenting detection rates of primary users with an order of 8 dB.

6
  • FRANCISCO ARY ALVES DE SOUZA
  • Application of DGS in H Format for Suppression and Attenuation of Higher Order Modes in Microfita Antennas

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • ALEXANDRE JEAN RENE SERRES
  • ALFREDO GOMES NETO
  • Data: Jun 10, 2020


  • Show Abstract
  • This thesis aims to characterize the DGS H filter to attenuate higher-order modes in microstrip antennas. The DGS H is designed independently of the antenna. The initial dimensions of H will be calculated using the desired attenuation range. After design and analysis of the filter response, the DGS H will be integrated into the antenna. The integration allows to eliminate filters between the signal source and the antenna. The reduction of insertion losses is the main advantage among others. The H filter is investigated through the frequency response. The dimensions of H (weights and bar) were parameterized from the initial dimension proposed here, which makes it possible to control the rejection band from the modes to be attenuated. This thesis presents the characterization of the DGS filter in H format for applications in microstrip antennas as well as a method to calculate the initial dimension of H. Two antennas were designed to prove the effectiveness of the proposal. These antennas are designed for the S and C bands (2.45 and 5.80 GHz). The results show the attenuation of the higher-order modes for the Microstrip Antennas studied in this thesis. The simulated and measured results are presented and discussed. The excited modes are investigated through the modal fields and frequency response. Prototype measurements were performed using a vector network analyzer (VNA) and an anechoic camera.

7
  • TÚLIO DE PAIVA MARQUES CARVALHO
  • Sabiá: Integrated Architecture for Authentication and Data Authorization Oriented to User Consent for Health Learning Ecosystems in Brazil
  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • KARILANY DANTAS COUTINHO
  • CYNTHIA ROSAS MAGALLANES
  • CRISTINE MARTINS GOMES DE GUSMÃO
  • JAILTON CARLOS DE PAIVA
  • Data: Jul 17, 2020


  • Show Abstract
  • Health information systems in Brazil have been designed and developed in a heterogeneous manner based on local regional characteristics, resulting in a lack of health information integrity. In this context, the Brazilian Ministry of Health pointed out the need for interoperability solutions of health information systems, noting the importance of integration with national databases and alignment with Brazilian data protection laws as well its application in education to aid with continuing education for health professionals. Therefore, this work presents Sabiá, a platform for authentication, authorization and data delivery based on user consent for health information systems in Brazil and currently applied in the context of health educational ecosystems. Sabiá's architecture is designed to achieve the following requirements: R1) Provide a Federated Identity; R2) Be a Federated Resource Manager; R3) Collect user data from different information systems and; R4) Deliver user data to systems based on user consent. Sabiá consists of three main components: 1) Sabiá Authorization Server, responsible for implementing Open Authentication; 2) Sabiá Collector, responsible for collecting data from different information systems and; 3) Sabiá Resource Server, responsible for delivering data previously authorized by the user to the systems. After analyzing historical data, R4 functionality was selected to be submitted to performance testing because it is the process that most affects overall system performance. The tests aimed at analyzing Sabiá's behavior in the heaviest scenario based on historical data. The results showed no flaws and indicated system stability and consistency, in which the user perceives a system reaction instantaneous, whose response time averages remained below 100 ms.

8
  • MÔNICA MARIA LEAL
  • Wavelet-Based Directional Protection Supported by Wavelet-Based Fault Classifier

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FELIPE VIGOLVINO LOPES
  • JOSÉ CARLOS DE MELO VIEIRA JUNIOR
  • KAI STRUNZ
  • Data: Aug 10, 2020


  • Show Abstract
  • Fast and accurate protections are required to ensure the safety of the power system. In
    this research, a new directional protection based on wavelet transfom is described by using
    only the first wavelet decomposition level. The scaling coefficients are used in replacement of
    the Fourier transform in order to recreate the conventional directional protection. The torque
    equations were mathematically redefined in the wavelet domain by using sampled voltages and
    currents. Regarding the protection activation, the wavelet coefficients are used for fast detection of fault-induced transients (wavelet activators) in order to reduce the relay operating time,
    whereas the scaling coefficients are used for backup activation in accordance with the overcurrent protection (wavelet overcurrent activators). In addition, a real-time fault classification
    method using the RT-BSWT applied to modal components of the Clarke transform was developed to support the directional protection. The method uses a simple threshold-based logic
    flow instead of a sophisticated artificial intelligence-based algorithm, and requires three-phase
    current measurements from only one terminal. Furthermore, by using the wavelet coefficients
    energy of RT-BSWT, the method is fast and accurate due to the extraction of both low- and
    high-frequency components of faults. Evaluations have proved the feasibility to rebuild the
    conventional directional protection by using the RT-SWT, which has provided better performance and faster operating time than the conventional protection based on the discrete Fourier
    transform (DFT). As new functionalities to the directional protection, the wavelet-based negative sequence unit can be used to identify the fault directionality to three-phase faults, even with
    severe voltage sags without memory strategies, which is not possible with the conventional protection. The fault classifier results have shown it is accurate and fast to identify all of the ten
    fault types successfully supporting the directional protection needs


9
  • DAVI HENRIQUE DOS SANTOS
  • Methodology for comparing autonomous sailboat control systems

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • ALEXANDRE DE MORAIS AMORY
  • ESTEBAN WALTER GONZALEZ CLUA
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • Data: Sep 4, 2020


  • Show Abstract
  • In this work we propose a methodology for estimating the performance and comparing control systems for autonomous sailboats. One of the biggest problem in mobile robotics research is the absence of standard tools and methodology for distribution/verification of implementations and the performance of the employed techiniques. Our approach consists of an framework for performance evaluation divided in three components: scope, metrics and scenarios. The scope define the parts of the system that are comparable and also presents a compreesive approach to define the basis navigation system for autonomous robot. The scenario represent situations that happen during sailboat missions such as keep the sailboat close to a desired waypoint (virutal anchoring), docking and tracking. Quantitative metrics are extracted by experiments in the scenario and are used to evaluate characteristics expected from control systems such as stability, energy consumption, robustness and efficiency, resulting in an initial classification of the control system. An initial implementation of the system is made using the Ardupilot framework, where some control techinique and metrics were implemented for first analisys. The level of analysis can be gradually improved by adding more control techinique and metrics.

10
  • LEONARDO ALVES DIAS
  • Parallel Implementation proposal of Clustering Algorithms in Hardware

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • DANIEL SABINO AMORIM DE ARAUJO
  • NANDOR VERBA
  • CARLOS ALBERTO VALDERRAMA SAKUYAMA
  • Data: Oct 5, 2020


  • Show Abstract
  • This work presents a study on data clustering algorithms implemented in dedicated hardware for applications in general, aiming to increase the processing speed. Clustering algorithms have been widely adopted to find patterns between data in different areas. However, these algorithms usually imply high processing complexity and, in addition, the amount of data currently stored is massive. Therefore, the need for high-throughput data processing has become even more critical, especially for real-time applications. One solution that has been adopted to increase processing speed is the use of parallel techniques implemented on dedicated hardware, which has proved to be more efficient compared to sequential systems. Therefore, this work proposes the fully parallel implementation of data clustering algorithms in hardware to optimize the processing time of systems in several areas, enabling applications for systems with a massive amount of data. A new proposal for implementations of the clustering algorithms K-means and Self-Organizing Maps are presented, together with an analysis of the results related to throughput and the hardware resource for different parameters. The implementations presented here point to a new direction associated with the implementation of clustering algorithms and can be used in other algorithms.

11
  • SÂMARA DE CAVALCANTE PAIVA
  • Wavelet-Based Systems for Frequency Monitoring and Islanding Detection of AC Microgrids.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • JOSEP MARIA GUERRERO ZAPATA
  • KLEBER MELO E SILVA
  • LEANDRO MICHELS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Oct 13, 2020


  • Show Abstract
  • The modern distribution system widely uses renewable energy sources (RESs) as a distributed generation that introduces problems like unintentional islanding, protection concerns, and reverse power flow. The RES intermittent characteristics can cause frequency deviations that could result in systems instabilities. In general, hierarchical structures implement these microgrids' power flow control management, composed of primary, secondary, and tertiary control layers. The primary control layer consists of inner current and voltage control loops, typically implemented via droop control loops, for the purpose of maintaining a stabilization of frequency and voltage amplitudes, as well as power-sharing. The principal drawbacks of droop control approaches are steady-state frequency and voltage deviations. For that reason, the secondary control layer is introduced to mitigate these deviations. The accurate knowledge of microgrid frequency deviations permits the implementation of proper frequency restoration. Besides, those microgrids could operate in the connected or islanding modes. Islanding or fault occurrences must be detected and treated to ensure system stability. This way, the continuous wavelet transform is employed for developing a hybrid islanding detection and a frequency monitor to fulfill the microgrid's requirements related to a secure islanding detection and a frequency restoration. In this Thesis, both systems' development is carried out, with the effectiveness of proposed methods evaluated and validated through experimental results.

12
  • MAXIMILIANO ARAÚJO DA SILVA LOPES
  • t-SNE parallel: A parallel technique for data dimensionality reduction applied in Smart Cities

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • ALUISIO IGOR REGO FONTES
  • CICILIA RAQUEL MAIA LEITE
  • DANIEL SABINO AMORIM DE ARAUJO
  • Data: Oct 16, 2020


  • Show Abstract
  • In recent years, the urban population has been growing rapidly around the world. To adapt to this population increase, mayors need to change the way they manage these large cities. Thus, the concept of Smart Cities gains strength and comes to change the way of life of the world population. The investment in this concept of smart cities is aimed at improving people’s management and quality of life. The biggest challenges in these systems are linked to the processing, visualization and analysis of the generated data, since when they work connected these systems generate a large mass of data, called Big Data, which need to be treated differently from conventional systems. For the visualization of the data, a device that can be used are the techniques for reducing the dimensionality, which bring the data from one n dimension to two or three dimensions, thus being perceptible to human eyes. One of the main problems involving Dimensionality Reduction techniques is related to the processing time, which makes them practically unfeasible to be applied to large masses of data. In this thesis, a way to decrease the processing time
    of these algorithms is suggested, by parallelizing the t-SNE algorithm. An analysis was performed on each part of the algorithm, verifying which sections could be parallelized and which sections would continue with their conventional processing. In this way, the parallelized algorithm showed better results than its conventional version, presenting itself as a more efficient and effective technique in Reducing the Dimensionality of data in order to optimize their visualization and analysis.

13
  • TIAGO ALVES DE ALMEIDA
  • Output Feedback Regulation and Constant Reference Tracking with Disturbance Rejection for Constrained Linear Systems via Controlled-Invariant Sets

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOÃO MANOEL GOMES DA SILVA JUNIOR
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • ROBERTO KAWAKAMI HARROP GALVAO
  • Data: Oct 16, 2020


  • Show Abstract
  • This work is concerned with design of output feedback controllers for constrained linear discrete-time systems via set-invariance techniques. In this regard, Output-Feedback Controlled-Invariant (OFCI) polyhedra are used to ensure that state and input constraints are satisfied all time even in the presence of additive disturbances and measurement noise. Necessary and sufficient conditions for a polyhedral set to be OFCI are presented, which can be checked by the solution of a set of Linear Programming (LP) problems. Then, a dynamic output-feedback compensator (possibly nonlinear) is proposed, through the construction of an OFCI set, from a pair composed by a conditioned-invariant and a controlled-invariant polyhedron. Based on the available measurements and on the state of the compensator, which constitutes an estimate of the system state, a suitable control sequence can be computed to enforce the constraints. The uncertainty on the state is progressively reduced using information about the contraction of the conditioned-invariant set. An LP problem is formulated to compute a control action that enforces state and control constraints and minimizes, one step ahead, a guaranteed distance from the admissible states to the origin. The problem of tracking a constant reference signal in the presence of constant disturbances is also considered for which the conception of the tracking controller is motivated from the stabilizing controller. With the current approach, as illustrated through numerical examples, by embedding the estimator in the compensator structure and using the OFCI concept, it is possible to obtain solutions with larger sets
    of admissible initial states and admissible initial estimation errors, compared to other approaches available in the literature.

14
  • THIAGO MEDEIROS BARROS
  • A Data-Oriented Process for Generation of School Dropout Prediction Model


  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • BETANIA LEITE RAMALHO
  • RAYMUNDO CARLOS MACHADO FERREIRA FILHO
  • PLACIDO ANTONIO DE SOUZA NETO
  • Data: Oct 22, 2020


  • Show Abstract
  • School dropout is an extremely complex problem, as it involves not only a variety of perspectives, but also a variety of different types of dropout behavior.  Historically, the most cited school dropout models had their origin in education, however the emerging area of Data Science applied in Education is capable of developing new predictive models, with generally better results when compared to the most used traditional statistical methods.   The main objective of this thesis is the proposition of a Process for the generation of a Predictive School Dropout Model based on Data Sciences.  To this end, a sequence of steps is defined in order to model an information flow from the definition of the problem to the generation of useful information for managers and teachers. The steps consist of:  Understanding the Problem, Understanding the Data, Feature Engineering, Feature Selection, Data Balancing, Models, Evaluation and Interpretation.  The proposal’s contribution is found in the indication of which techniques and algorithms should be used in each phase of knowledge discovery, and show that the phenomenon of school dropout must be addressed as a problem of imbalanced classes, which must use tools and appropriate metrics, in order to generate a robust and easy to interpret prediction model. The proposed process was validated on educational and socioeconomic data of students at  Federal Institute of Rio Grande do Norte (IFRN).

15
  • TALES VINÍCIUS RODRIGUES DE OLIVEIRA CÂMARA
  • Automatic Modulation Classification in Impulsive Environments Based on Cyclostationary Features

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • WAMBERTO JOSÉ LIRA DE QUEIROZ
  • JOILSON BATISTA DE ALMEIDA REGO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • PEDRO THIAGO VALERIO DE SOUZA
  • Data: Oct 23, 2020


  • Show Abstract
  • The rapid growth of applications supported by wireless communications systems drives the search for new communications systems that allow to efficiently explore the frequency spectrum, such as systems based on cognitive radio. The cognitive radio can be defined as an intelligent communications system, capable of adapting autonomously to the communication channel, through the reconfiguration of its operating parameters. An important property of cognitive radios is the ability to automatically recognize the type of modulation employed in an RF signal, thus enabling interoperability between systems, improving spectral efficiency, or even enabling electronic surveillance (in military application contexts) ). This attribute is known as automatic modulation classification (AMC). Among the AMC techniques that characterize the state-of-the-art, are those that are based on the detection of patterns obtained from the analysis of second order cycle stationary characteristics. Although very widespread, these techniques are unable to recognize some types of digital modulations, such as high-order M-QAM and M-PSK modulations. On the other hand, the higher order cycle stationary analysis techniques, used to extract singular descriptors of these modulations, have a very high computational cost and are only suitable for communication environments with AWGN noise. Although the AWGN noise model is widely used to characterize wireless communication channels, there are several practical scenarios that are better modeled by non-Gaussian distributions, such as HF communication, whose environment presents a strong contamination by impulsive noise. Recently, two new cyclostationary analysis functions, the lower order fractional cyclic autocorrelation function (FLOCAF), and the cyclic current correlation function (CCF), were defined and evaluated for the purpose of spectral sensing in impulsive environments, being the spectral sensing a less complex problem in relation to the automatic classification of modulations. In fact, knowing that there was no satisfactory solution in the literature for the automatic classification of high-order modulations in channels with impulsive noise, this problem was addressed in this work. In this work, automatic modulation classification architectures are developed based on the FLOCAF and CCF cyclostationary functions, combined with decision tree classification and logistic regression techniques. The architectures were developed for the recognition of BPSK, QPSK, 8-QAM, 16-QAM, and 32-QAM digital modulations, and evaluated in different contexts of alpha-stable additive noise contamination. The results showed that all architectures were able to operate in impulsive environments, however, architectures based on CCF were the most efficient.

16
  • ADELSON MENEZES LIMA
  • Application and Analysis of Metamaterial Cells Arrays in the Microfita Antennas Design

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • FRANCISCO DAS CHAGAS BARBOSA DE SENA
  • HUMBERTO DIONISIO DE ANDRADE
  • JOSE PATROCINIO DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Oct 23, 2020


  • Show Abstract
  • Obtaining and integrating solutions for technological applications in the communications area has led researchers to investigate various types of materials, with emphasis on this case for the case of metamaterials in the construction of microwave circuits. On the other hand, due to the ease of construction, microstrip antennas have used metamaterials that are obtained artificially by allowing changes in their electromagnetic properties. In this context, the present work proposes a metamaterial cell for the development of the configuration of periodic arrangements, immersed in the dielectric substrate, in the construction of the microstrip antennas. For the design of the cell and microstrip antennas, the operating frequency of 5.8 GHz was used. Simulations with the HFSS® software that uses Finite Elements as a numerical method, were performed to analyze the electromagnetic characteristics of the cell and the parameters of the antennas. Numerical results performed with the cell understudy, has a strong influence of magnetic permeability on metamaterial properties, at the desired frequency. The first case study showed greater bandwidth and better impedance matching. In the second, despite obtaining a greater bandwidth, a decrease in the resonance frequency was observed, and a change in the impedance matching when the cells were rotated. To validate the results, prototypes were built for the first case under analysis and the measured results were compared to those obtained numerically, showing a good agreement. In the second study, only simulated results were obtained, considering the angle of rotation of the cells, ranging from 0 to 90 degrees with intervals of 15 degrees. For all the studied structures, the parameters analyzed were the reflection coefficient (S11), bandwidth, Smith chart, radiation diagram (2D and 3D), gain, electric field distribution, and surface current density.

17
  • ARTHUR SALGADO DE MEDEIROS
  • Direct Control of the Rotor Voltage of a Doubly Fed Induction Generator by means of a Restricted Optimization Process in Real Time

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCUS VINICIUS ALVES NUNES
  • RICARDO FERREIRA PINHEIRO
  • THALES AUGUSTO DE OLIVEIRA RAMOS
  • UBIRATAN HOLANDA BEZERRA
  • Data: Oct 30, 2020


  • Show Abstract
  • The constant growth in the potential for generating energy from wind sources has been highlighted on the world stage. Global behavioral changes in search of sustainable development and consumption, replacing fossil fuels aiming at improving the quality of life and preserving the planet, are important factors for the continuation of this growth, due to the increasing need for renewable energy sources. The wind energy conversion systems that use the Doubly Fed Induction Generator - DFIG, are the most popular today. Advantages such as reduced mechanical load, simple picth control, control of active and reactive power, lower power converters that mean less switching losses, reduced converter costs, less harmonic injection into the network, put it ahead of turbine topologies with synchronous generators or induction generators with squirrel cage rotors. This thesis aims to present and demonstrate the feasibility of using a new approach on voltage control, active and reactive power control and power factor control through direct control of the voltage applied to the DFIG’s rotor, by the Rotor Side Converter - RSC. This voltage is determined analytically, solving a restricted optimization process in real time. A system of equations derived from the equivalent circuit is adopted to represent the desired operating point of the DFIG, and the solution of this system defines the values of the rotor supply voltage coordinates, in steady state. A new control strategy is proposed to reach the rotor voltage reference values, without violating the limits existing in other variables. This strategy is designed so that the speed of evolution of the voltage applied to the rotor, is governed by the dynamic evolution of the mechanical speed of the rotor. An optimization process was formulated to minimize the time of convergence of the rotor speed, restricting transitory variations in the net power generated, in order to accelerate the machine, without exceeding the current limits. Following recent trends in solutions with a reduced number of sensors, only measurements obtained from the stator sensors (voltages and currents) are used. In this way, the angular velocity and rotor currents are estimated in real time. An algorithm for estimating inductance is also included, preventing deviations from the nominal value could lead to false reference voltages or changes in reactive control. In addition, a method for defining the pitch angle and the reference speed is proposed, using the Newton-Raphson numerical solution method.

18
  • PETRÚCIO RICARDO TAVARES DE MEDEIROS
  • Visual Stimulus Detection Using Multiple Foveas

  • Advisor : RAFAEL BESERRA GOMES
  • COMMITTEE MEMBERS :
  • BRUNO MOTTA DE CARVALHO
  • ESTEBAN WALTER GONZALEZ CLUA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • RAFAEL BESERRA GOMES
  • ROBERTO MARCONDES CESAR JUNIOR
  • Data: Oct 30, 2020


  • Show Abstract
  • The multifoving technique allows the addition of several focuses in the image, which can be explored as points of visual attention in contexts of detection, identification and / or object recognition. However, the use of the multifoving technique requires knowledge of the position of visual stimuli. In this work we propose a new approach to detect visual stimuli using the structure of multiple foveas. For this, we use mathematical strategies adapted to the context of computational vision, which take into account the distribution of the foveas to estimate the location of visual stimuli in the image. The mathematical strategies adopted were the descent of the gradient (potential field), maximum likelihood, multilateration, trilateration and barycentric coordinates. The results show that the algorithms converge for the position of the visual stimulus, with the exception of the local potential intersection algorithm due to the sensitivity to local minimums. In addition, the algorithms that use potential fields require more processing time and computational resources compared to other strategies. However, it is possible to affirm that three fóveas are sufficient to estimate the position of a visual stimulus in the image making use of the trilateration algorithms and baricentric coordinates. We conclude that the multi-panning associated with mathematical strategies can be applied in visual detection and presents convergence with at least three foveae.

19
  • REUBER REGIS DE MELO
  • RFID in IoUT Using a Dielectric Attenuation Structure for Application as Moisture Sensor


  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOSE PATROCINIO DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁDLLER DE OLIVEIRA GUIMARÃES
  • Data: Oct 30, 2020


  • Show Abstract
  • Advances in Internet of Things (IoT) applications have provided the development of new paradigms in this area, such as the Internet of Underground Things (IoUT). Research shows the potential of IoUT systems, mainly in precision agriculture, in which data it’s collected by different devices interconnected in a communication network. These data can facilitate decision-making about the management of agricultural activities. An important component in the architecture of IoUT is Underground Things (UT) responsible for sensing soil parameters, such as temperature and moisture. In view of this, the Radio Frequency Identification (RFID) technology has been shown promising for the development of UTs, mostly due to the ability of RFID tags to operate as sensors. However, the adaptation of wireless communication in IoUT systems for application in underground conditions represents a challenger yet. In this context, the proposal of the work is to develop a UT based on RFID technology for sensing soil moisture. The UT proposed is formed by a rectangular patch microstrip antenna designed to operate at Ultra High Frequency (UHF), connected to a passive UHF RFID tag chip. The RFID tag in buried in the soil and functions as a moisture sensor. To reduce the effects of soil moisture on the RFID tag, the microstrip antenna designed in the systems was encapsulated in a Dielectric Soil Attenuator (DSA). The DSA is formed by multilayers made of natural carnauba wax and applied over the antenna. Simulated and experimental results were analyzed to verify the effectiveness of the DSA on the antenna parameters at different levels of moisture and soil types. Measurements of the Received Signal Strength Indicator (RSSI) were also performed using a UHF RFID reader, and thus, finding a relationship with the moisture present in the soil. The obtained value shows that the DSA reduces variations in the antenna parameters such as gain and reflection coefficient (S11) caused by soil moisture. Statistical analyzes of the RSSI measurements showed that the proposed UT can work as a soil moisture sensor.

20
  • DANIELE MONTENEGRO DA SILVA BARROS
  • Architecture of Digital Health Based on Machine Learning for Diagnosing Eye Diseases: a study applied to glaucoma

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CÉSAR ALEXANDRE DOMINGUES TEIXEIRA
  • ALEXANDRE CHATER TALEB
  • FRANCISCO MILTON MENDES NETO
  • JAILTON CARLOS DE PAIVA
  • Data: Nov 6, 2020


  • Show Abstract
  • The development of new technologies has been essential for the diagnosis and treatment of eye diseases. In this context, using machine learning (AM) and deep learning (DL) techniques for the classification and detection of ocular analogies has resulted in recent research. In this perspective, the present's objective is to develop a technical classification service for DL, web technologies, and cloud services, making a case study on glaucoma. Glaucoma is an asymptomatic disease that can cause irreversible blindness if diagnosed late. The type of image used in the analysis was retinography since its acquisition is inexpensive, and a non-dependent operator performs the examination. That is, it does not require the presence of the doctor. As a result, an intelligence architecture was designed that implemented and trained several DL architectures. The learning transfer technique (transfer learning) was used to reduce training time and optimize the method. Another essential strategy is the data augmentation process (data argumentation) to minimize network overfitting, thus preventing the network from generalizing in the test set. A cloud service was developed, a platform that uses pre-trained models to identify new images' according to the input's mass of data.

21
  • TIAGO DOS SANTOS BEZERRA
  • Application of EBG (Electromagnetic BandGap) on Frequency Selective Surfaces to Suppress Higher Order Modes

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • MAURICIO WEBER BENJÓ DA SILVA
  • Data: Nov 6, 2020


  • Show Abstract
  • We propose an application of electromagnetic bandgap (EBG) for suppression or reduction of higher order resonant modes in frequency selective surfaces (FSS), not yet studied in the literature.

                The study consists of an application of a rectangular periodic array of circular air holes in FSS dielectric substrate to create rejection bands and to suppress or reduce specific resonant frequency modes. Another type of unconventional air hole used was the square shaped holes, aiming to reduce the computational effort during the simulations.

                Optimizations with genetic algorithms were implemented to optimize the physical parameters of the holes, aiming at the suppression in the desired frequency range.

                In order to prove that the prohibited bands occurred in the desired frequency bands, a Brillouin dispersion diagram was constructed verifying that the structures acted as EBG

    Seven prototypes were manufactured and the results measured compared to the simulated results obtained in ANSYS HFSS. A good agreement between the results is observed. Simulations and measurements show suppression levels of up to 6 dB. The simulation time of the FSS with EBG of square holes showed a reduction of 70% in relation to the simulation time of the FSS with EBG of cylindrical holes.

22
  • EDNARDO PEREIRA DA ROCHA
  • ALGORITHM FOR A LINEAR STATE ESTIMATOR BASED ON CURRENT SUMMATION METHOD APPLIED TO THREE-PHASE POWER DISTRIBUTION NETWORKS

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • MADSON CORTES DE ALMEIDA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • UBIRATAN HOLANDA BEZERRA
  • Data: Nov 20, 2020


  • Show Abstract
  • The way in which the energy companies have been operating their substations and supervising their feeders in the distribution networks has undergone a major modernization process in the past two decades. As the number of consumers and the physical extension of the infrastructure increased, there was a greater demand for equipment and monitoring techniques that would guarantee the reliability of these systems.This work presents the development of a new algorithm based on currents summation method,for implementation of a linear formulation of the state estimation problem in three-phase distribution networks, applied in the normal operation regime and under fault condition.In the normal operating regime, the modules of branch and node currents are estimated based on the weighted least squares method and a load adjustment algorithm, which makes it possible to obtain an estimative of technical losses, active and reactive power flows and the system voltage profile.For validation, data from two 13.8 kV real distribution systems were used to test the method. The meters located in the analyzed feeders provide the values of the measured quantities and an approximation of the average power factor of the loads located downstream from these measurement points, while pseudomeasures are used to make the system observable. In the proposed method, an iterative reestimation algorithm based on system scanning was implemented, where the parameters estimated in the first estimate are used to update the loads, branch currents and new variances.In the second stage of this thesis, an algorithm for fault location was developed using a system sweeping method associated with the proposed state estimator. In this case, in addition to considering the short-circuit current measured at the substation, the currents of each load were estimated during the fault to verify their influence on the fault location process.In this condition, a real distribution system was modeled in the ATP softwarein order to emulate measurements of voltages and currents at the substation, and voltage magnitudes registered by other meters during the fault. Factors such as the influence of the fault resistance, the type of fault, the system loading and the fault location were tested. The results obtained show that the developed method is able to provide the system status with adequate precision for distribution systems with a reduced number of measurement points along the feeder, besides presenting a low computational processing time and simplified modeling. The obtained results show that the developed method can provide the state of the system with adequate precision for distribution systems with a reduced amount of measurement points along the feeder, besides presenting a low computational processing time and simplified modelling. There was also a proximity between the proposed estimator and the re-estimation method, proving that the load adjustment process already provides pseudo-values close to the estimated values. Under a fault condition, the algorithm showed promise in its function, locating faults with a small error margin in most simulations.

23
  • ISRAEL EDUARDO DE BARROS FILHO
  • An anti-collision algorithm for large-scale RFID in noisy environments applied to the Industrial Internet of Things

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • CARLOS MANUEL DIAS VIEGAS
  • DANIEL GOUVEIA COSTA
  • IVAN MULLER
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Nov 30, 2020


  • Show Abstract
  • The Industrial Internet of Things (IIoT) is often presented as a concept that is significantly changing the technological landscape of industries, through automation procedures and identification of relevant objects. For this, however, reliability and performance issues must be considered when providing anticipated communication services. By employing Radio Frequency Identification (RFID) in the IIoT context, several previous studies have worked to improve the efficiency of RFID communications systems, generally defining mathematical models for planning and evaluating quality. However, such models are designed based on error-free communications, which is in fact unrealistic when considering the error-prone nature of wireless communications in industrial plants. Therefore, this thesis proposes a new anti-collision algorithm for RFID together with a formal model based on Generalized Stochastic Petri Nets (GSPN) to evaluate RFID communications, modeling different possibilities of errors between readers and RFID tags. Since this proposal uses the EPCglobal UHF Class 1 Gen2 parameters as a reference, which are already adopted by the Dynamic Frame Slotted Aloha anti-collision protocol for passive RFID systems, this model can be explored to assess the performance of different RFID access protocols when assuming noisy channels, supporting better comparisons between different algorithms and protocols. The results showed that the proposed algorithm is able to present a better performability in relation to the other evaluated protocols, mainly in the presence of noisy channels if a large number of tags to be read. Simulation scenarios are defined to provide reliability and performance results when evaluating RFID tag readings, which are valuable when designing and maintaining IIoT applications.

24
  • LEONARDO ANGELO VIRGINIO DE SOUTO
  • Extracting Stairs and Doors as Natural Landmarks for Mobile Robot Localization from Clouds of 3D Edge-Points

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • BRUNO MARQUES FERREIRA DA SILVA
  • ANDERSON ABNER DE SANTANA SOUZA
  • TIAGO PEREIRA DO NASCIMENTO
  • Data: Nov 30, 2020


  • Show Abstract
  • Natural landmarks are the main features in the next step of the research in localization of mobile robot platforms. The identification and recognition of these landmarks are crucial to better localize a robot. To help solving this problem, this work proposes an approach for the identification and recognition of natural marks included in the environment using images from RGB-D sensors. In the identification step, a structural analysis of the natural landmarks that are present in the environment is performed. The extraction of edge points of these landmarks is done using the 3D point cloud obtained from the RGB-D sensor. These edge points are smoothed through the $Sl_0$ algorithm, which minimizes the standard deviation of the normals at each point. Then, the second step of the proposed algorithm begins, which is the proper recognition of the natural landmarks. This recognition step is done as a real-time algorithm that extracts the points referring to the filtered edges and determines to which structure they belong to in the current scenario: stairs or doors. Finally,  the geometrical characteristics that are intrinsic to the doors and stairs are identified. The approach proposed here has been validated with real robot experiments. The performed tests verify the efficacy of our proposed approach. 

25
  • DANIEL NOBRE PINHEIRO
  • Convex fuzzy k-medoids clustering

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • CAROLINE THENNECY DE MEDEIROS ROCHA
  • DANIEL ALOISE
  • ERALDO LUIS REZENDE FERNANDES
  • MARIÁ CRISTINA VASCONCELOS NASCIMENTO ROSSET
  • SAMUEL XAVIER DE SOUZA
  • Data: Dec 16, 2020


  • Show Abstract
  • The k-medoids model is one of the most popular clustering methods. In this work, we propose the Convex Fuzzy k-Medoids Problem (CFKM), which not only allows one object to be assigned to multiple clusters, but also allows a cluster to be represented by multiple medoids. The proposed model is convex and thus is robust to initialization. To evaluate the importance of CFKM, we compare it with another two fuzzy k-medoids models: the Fuzzy k-Medoids Problem (FKM) and the Fuzzy clustering with Multi-Medoids Problem (FMMdd), both solved by heuristics due to their computational complexity. Experiments with both synthetic and real-world data, along with an user survey, show that CFKM is not only more robust to the choice of parameters of fuzzy models, but also is the only able to reveal important aspects of inherently fuzzy data.

2019
Dissertations
1
  • MARIA GRACIELLY FERNANDES COUTINHO
  • Deep Neural Network Hardware based on Stacked Sparse Autoencoder

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • CARLOS ALBERTO VALDERRAMA SAKUYAMA
  • DIOMADSON RODRIGUES BELFORT
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Jan 17, 2019


  • Show Abstract
  • The deep learning techniques have been gaining prominence in world research in the past years. However, the deep learning algorithms have high computational cost, making it hard to apply in several commercial applications. On the other hand, new alternatives have been studying to accelerate complex algorithms, among these, those based on reconfigurable hardware has been showing very significant results. Therefore, the objective of this work is the hardware implementation of a neural network for the use of algorithms with deep learning. The hardware was developed on Field Programmable Gate Array (FPGA) and supports Deep Neural Network (DNN) trained with the Stacked Sparse Autoencoder (SSAE) technique. In order to allow DNNs with many inputs and layers on the FPGA, the systolic array technique was used in all developed hardware. The details of the architecture designed on the FPGA were evidenced, as well as the occupation data on hardware and the processing time to two different implementations. The results show that both implementations achieve high throughputs allowing the use of Deep Learning techniques in massive data problems.

2
  • YURI PEDRO DOS SANTOS
  • System of Detection and Classification of Vocal Pathologies Based on the Correntropy Spectral Density

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ALUISIO IGOR REGO FONTES
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • SUZETE ELIDA NOBREGA CORREIA
  • Data: Jan 18, 2019


  • Show Abstract
  • Vocal pathologies negatively affect the social and professional life of the sick, some of which may even lead to death if they are not treated quickly. Among the main procedures for the diagnosis of vocal disorders we can cite: laryngoscopy, perceptual-auditory evaluation, acoustic analysis of the voice, aerodynamic evaluation and self-evaluation of the voice by the patient. However, these procedures are usually invasive or inaccurate. Therefore, digital signal processing techniques have been used in the design of non-invasive systems to aid in the diagnosis of vocal tract pathologies. In this work a system of detection and classification of vocal pathologies is presented, using a classification technique based on descriptors obtained through the Correntropy Spectral Density (CSD) function, defined as the Fourier transform of the autocorrelation function. The descriptors obtained have information of second-order and higher-order statistical moments of the speech signal, through which vocal pathologies can be efficiently detected and classified. The classification is made by a neural network multilayer perceptron (MLP), performing a binary classification between normal and pathological voices and then between pathologies (edema and nodule). The classifier was evaluated by computer simulation, and the results indicate a high hit rate of detection and classification among pathologies.

3
  • RUTE SOUZA DE ABREU
  • A methodology for detection of causality relations among discrete time series on systems

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • RODRIGO SIQUEIRA MARTINS
  • Data: Jan 25, 2019


  • Show Abstract
  • The need for detecting causality relations among process, events or variables is present in many areas of knowledge e.g., distributed computing, the stock market, industry, medicine, etc. This occurs because the knowledge of these relations can often be helpful in solving a variety of problems. For example, maintaining the consistency of replicated databases when writing distributed algorithms or optimizing the purchase and sale of stocks in the stock market. In this context, this dissertation proposes a new methodology for detecting causality relations in systems by using information criteria and Bayesian networks to ensemble the most probable structure of connections among discrete time series. Modeling the system as a directed graph, in which the nodes are the discrete time series and the edges represent the relations, the main idea of this work is to detect causality relations among the nodes. This detection is made using the method of transfer entropy, which is a method to quantify the information transferred between two variables, and the K2 algorithm: a heuristic method whose objective is to find the most probable belief-network structure, given a data set. Because K2 depends on the premise of having a previous structure that defines the hierarchy among the network nodes, it is proposed in the methodology the creation of the previous ordering on the nodes considering direct and indirect relations, and the modeling of these relations according to the lag between cause and effect. In addition, knowing that the K2 algorithm considers that each case of the data set occurs simultaneously, the proposed methodology modifies the original algorithm by inserting the dynamics of these lags into it. This modification provides a mechanism for comparing direct and indirect causality relations regarding its contribution to the structure. As the result, it is obtained a graph of causality relations among the series, with the relation's lags being explicit.

4
  • YURI THOMAS PINHEIRO NUNES
  • Data-Based Approach to Parametric Configuration of Industrial Alarms

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • CLAUBER GOMES BEZERRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jan 25, 2019


  • Show Abstract
  • Industrial plants are composed of processes that add up to thousands of variables. To ensure safety and quality of operation, these processes are monitored and alarms are configured to indicate a possible malfunction. Among the most common problems associated with industrial alarms we can mention: high occurrence of false alarms, missed alarms and chattering alarms, operator overload and alarm flooding. These problems are related to the process of selection of the monitored variables, the techniques of activation and deactivation of alarms, among other characteristics of the process and the alarm system. This work focuses on defining an approach to configure efficient and significant alarms for the operator. The approach proposed here is inspired by the workflow of a data scientist who initially needs to identify the characteristics of the databases used to then apply transformations that make the data more suitable allowing the extraction of valuable information. Many times the scientist is interested in creating a model that describes the data or makes predictions possible. This is a very similar task of alarm configuration where it is necessary to select the relevant variables and to configure the settings of each alarm in order to classify the operation of the process as appropriate or not and to help identify the fault. The approach proposed here consists of four parts: description of data, selection of variables, tuning and performance evaluation. During the description step, relevant information about the data is obtained, such as the presence of events, the number of different events, the duration of events, etc. In the selection stage, the relevant variables for detection of abnormalities are defined. The tuning of alarms is similar to a training process, where a model is built to describe the behavior of the data. Finally during the evaluation, the settings found are applied to a process history to asses whether the settings behave in a way that meets security and quality constraints. As a case study, an industrial alarm configuration was obtained for the Tennessee Eastman Process which is a simulator widely used by the academic community.

5
  • MAX RODRIGUES MARQUES
  • Evaluation of Wavelet-based Protection Applied in a Doubly-fed Induction Generator

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • CAMILA MARA VITAL BARROS
  • FLAVIO BEZERRA COSTA
  • LUCIANO SALES BARROS
  • RODRIGO PRADO DE MEDEIROS
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Jan 28, 2019


  • Show Abstract
  • With the globalization and the rapidly increasing global energy demand, it has been seeking the sustainability guarantee because the growing concern to preserve the planet for future generations. Therefore, investments in clean and renewable energy sources, such as wind power generation, have gained space in research groups in order to overcome their drawbacks and improve the benefits. The doubly fed induction generator (DFIG) is the predominant one in the market. Nevertheless, considering the electrical failures inherent to this generator type and the ones in the power system (PS), the protection of its elements is an important topic that still does not have comprehensive studies. This dissertation investigates the techniques used to perform the internal and external protections applied to the DFIG topology. As well as, it is presented the theoretical fundamentals about the wind energy conversion systems (WECS), the wavelet transform, and some relay-based protections. DFIG electrical signals in case of machine terminal faults is analyzed and evaluated using the real-time stationary wavelet transform with boundary effect (RT-BSWT). Furthermore, qualitative studies on wavelet overcurrent, wavelet under-voltage, directional, and differential protections will be introduced in order to assess and to validate these new protection trends applied to WECS.As also, to develop a preliminary method of identifying internal faults in a DFIG. Analysis applying these protections to real signals, collected by an experimental test-bench with DFIG, demonstrated which the used mathematical tools had good performances for protection against electrical faults at the common connection point.

6
  • KAIO MÁRCIO DA COSTA BANDEIRA
  • Multiband Microstrip Antenna for Wireless Communication Applications in IEEE 802.11ax and IEEE 802.11ah Standards

  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • VALDEMIR PRAXEDES DA SILVA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • FRANCISCO DE ASSIS BRITO FILHO
  • Data: Jun 27, 2019


  • Show Abstract
  • In view of the evolution of the standards of wireless communication systems, where there is a need for performance in several frequency bands, it is indispensable to design devices capable of meeting the requirements that this progress demands. The antennas are elements that play a fundamental role in these systems, in which planar microstrip antennas have been demonstrated with high evidence due to their low profile, miniaturized devices, low manufacturing cost and are easily integrated with the devices. With the objective of optimizing the occupation of physical space in the transceivers and in the end devices of the users, this work presents the proposal of a microstrip antenna based on a planar monopole with ground plane with slits for operation in multiple bands to meet new systems of wireless communications such as IEEE 802.11ax and IEEE 802.11ah. The process of design formation and design of the structure will be presented, considering the most recent research in the specialized literature. For the purposes of analysis, simulations were performed by the Finite Element method implemented through the commercial software Ansoft HFSS. Some initial prototypes were fabricated for purposes of validation of the preliminary results of this work. The experimental characterization of these prototypes was performed through a vector network analyzer. In view of the comparisons between simulated theoretical results and the preliminary experiments, it can be affirmed that a good agreement between them is observed corroborating with the studies previously developed.

7
  • MÁRIO GUILHERME FLORES FIGUEREDO
  • Performance of audio signals positioning algorithms in environments with impulsive noise

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • FRANCISCO CARLOS GURGEL DA SILVA SEGUNDO
  • VALDEMIR PRAXEDES DA SILVA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jun 28, 2019


  • Show Abstract
  • Recently, with increasing processing capacity as well as the miniaturization of electronic devices, a number of commercial systems based on the location of audio signals have emerged, such as shot spotter and voice monitoring systems, and residential, among them, entertainment system and home automation (e.g. Google Home and Amazon dot). In the literature, the classical methods of Direction-of-Arrival (DoA) are commonly evaluated in acoustic environments submitted to White Additive Gaussian Noise (AWGN). However, acoustic environments are also subject to impulsive noise, under which the classical methods of DOA estimation have degraded performance. In this way, besides describing and evaluating the performance of classical parametric and non-parametric DOA methods, and demonstrating their respective performances in acoustic environments submitted to AWGN, this work also proposes to present their performance when subjected to the impulsive noise modeled by the Gaussian mixing method. As a last contribution, the methods are tested using real signals from a proprietary acquisition system.

8
  • SAMUEL BELARMINO DE PAIVA
  • Analysis and Synthesis of Bioinspired Frequency Selective Surfaces Using Neural Networks for Applications in Wireless Communication Systems

     

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • GLAUCO FONTGALLAND
  • HERTZ WILTON DE CASTRO LINS
  • JOSE ALFREDO FERREIRA COSTA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Jul 1, 2019


  • Show Abstract
  • This work describes the analysis of Bioinspired Frequency Selective Surfaces (BFSS) for applications in wireless systems, operating in the C band, Ku band and UWB (ultra-wideband). Simple and coupled BFSS structures are considered. The BFSSs have array elements with the four-leaf clover-shaped and maple leaf-shaped, and presented dual-band response, with the operating frequencies in the C and Ku bands. For the development of BFSSs with the ultra-wideband, a cascade structure was developed, in which a FSS with elements with patches with the shape of square loops was coupled to the BFSSs. In addition, the four-leaf clover BFSS synthesis was developed using an artificial neural network with a cascade feedforward architecture and Bayesian regularization training algorithm to obtain the specifications of resonance frequency and respective desired bandwidths. The numerical values obtained by simulations for the developed prototypes were obtained by the ANSYS HFSS software. Prototypes were manufactured and experimentally characterized. The measured results were compared with the simulated ones and a good agreement was observed.

9
  • LUIZ ANDRÉ PONTAROLO
  • Adjustment of PID Controller by an Autotuning Method Based on Robustness Estimate

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • OSCAR GABRIEL FILHO
  • Data: Jul 5, 2019


  • Show Abstract
  • In this work a process of adjustment of PID  controllers using the auto tuning method oriented to the robustness of the system and implemented in a Programmable Logic Controller (PLC) with the use of relay experiments is presented, with possibility of application in PI-D controllers. The method was developed through the adaptation of methods directed to existing PI controllers, with the objective of using few iterative structures, allowing the implementation in PLC, as well as improving the performance in the transient response of the system. Robustness is indicated by the maximum sensitivity of the system. Relay experiments provide frequency response points that allow calculation of parameters that modify the original terms of the controller in order to remove the points from the interior of the maximum sensitivity circle. Results of two PLC applications of different didactic systems allowed comparison with an existing PI controller tuning method and the demonstration of the effectiveness of the method.

10
  • JOÃO RICARDO TAVARES GADELHA
  • Model Predictive Control Applied to a Plunger Lift Artificial Elevation System

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • ANDRE LAURINDO MAITELLI
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • Data: Jul 12, 2019


  • Show Abstract
  • During the productive life of most gas wells there is an accumulation of liquid at the bottom of the well which causes a pressure contrary to the flow of the reservoir, reducing the production of the well. In this way, one of the possible artificial lift methods to solve this problem is represented by the Plunger Lift. It consists of a low-cost installation and maintenance technique that uses a piston to, among other uses, increase the efficiency of liquid removal from the system. However, this method requires a well-adjusted controller to appropriately define the opening and closing periods of a motor valve installed in the wellhead for production control. Predictive control is a technique that can be applied to perform such task, performing predictions of the future behavior of the plant in order to obtain its optimum performance. In this work, the implementation and application of a linear predictive controller to a simulated well operated by Plunger Lift was performed. The controller was applied under different conditions of draining ability, with and without, of the gas present in the annular space. Results of MPC without drainage were compared with conventional versions of Plunger Lift control in the oil industry through graphical analysis and observation of performance parameters. This controller obtained better results regarding the control of the average speed of plunger ascent and accumulated production. In the comparison of MPC with and without drainage, the version capable of manipulating the gases from the annular space was able to cause the system to operate at speeds of piston ascent in safer ranges.

11
  • RAFAEL MAGALHÃES NÓBREGA DE ARAÚJO
  • Development and Evaluation of a Self-sufficient Photovoltaic-Thermoelectric System

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALBERTO SOTO LOCK
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • Data: Jul 29, 2019


  • Show Abstract
  • The generation of electric energy by a photovoltaic cell mainly depends on the operating temperature and solar irradiance that falls on it. The operating temperature can be controlled by means of thermoelectric cells working as coolers. This work proposes a self-sufficient system in which photovoltaic cells are cooled by thermoeletric cells. It also proposes an analysis on which situations a favorable energy yield can be reached. Simulations have been performed taking into account diverse sets of solar irradiance, wind speed, and electric power dedicated to the cooling. Results suggest that the proposed system reaches positive net yield in situations that environmental variables lead to higher photovoltaic panel operating temperature combined with controlled low power dedicated to the thermoeletric cells.

12
  • NAYANA LETÍCIA DE MORAIS VIANA
  • Design of a low consumption, low noise and low offset instrumentation amplifier for portable applications

  • Advisor : DIOMADSON RODRIGUES BELFORT
  • COMMITTEE MEMBERS :
  • DIOMADSON RODRIGUES BELFORT
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • ANTONIO WALLACE ANTUNES SOARES
  • FRANCISCO DE ASSIS BRITO FILHO
  • Data: Jul 29, 2019


  • Show Abstract
  • In this work is presented a low power instrumentation amplifier using 0.6 μm CMOS technology. It is initially shown the theoretical background about the chosen application: treatment of biopotentials. Next, we present the architectures of instrumentation amplifiers present in the literature focused on biopotentials, as well as low power and low noise configurations. A study is also carried out on the types of pseudo-resistors present in the literature. Once this is done, all the methodology used to perform this work is presented, such as the choice of the architecture used, how the system design is performed and what types of simulations are used to evaluate the performance of the system. Finally, it can be concluded that using integrated circuits with CMOS technology can enable numerous low-power portable applications that use the acquisition of biopotentials, thus justifying such design.

13
  • ANDREW VINÍCIUS SILVA MOREIRA
  • Photovoltaic Panel performance against partial shading using intelligent bypass diode and clustered adaptive P & O

  • Advisor : LUCIANO SALES BARROS
  • COMMITTEE MEMBERS :
  • LUCIANO SALES BARROS
  • ANDRE LAURINDO MAITELLI
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • Data: Jul 31, 2019


  • Show Abstract
  • The exponential growth in the use of photovoltaic solar (PV) energy makes that the question of the performance of panels connected to the grid is extremely relevant, because its efficiency is relatively low if compared to other energy sources. Among the main studies, the following stand out: Partial Shading (PS) and Maximum Power Point Tracking (MPPT). The PS refers to the distinct levels of irradiance along the photovoltaic panel and the MPPT refers to the maximum power point tracking according to ambient conditions. In this work, a current photovoltaic panel with 72 cells, containing a modern smart bypass diode configuration was modeled and simulated. In order to verify the performance of the photovoltaic panel were simulated partials shadings and the maximum power point tracking using the simplest MPPT technique: Perturb & Observe (P&O), however modified with adaptive step and clustered.

14
  • ALESSANDRO DE SOUZA LIMA
  • Analysis of Photovoltaic Panels Facing Partial Shading Using Magic Square and Adaptive P & O.

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • LUCIANO SALES BARROS
  • Data: Jul 31, 2019


  • Show Abstract
  • Partial shading decreases the power generated by solar panel arrangements. In this condition, some panels end up receiving solar radiation different from others, causing multiple peaks in P-V and I-V, resulting in losses. This work aims to reduce the losses caused by partial shading from reconfigurations of the panel arrangements, in conjunction with an adaptive P & O MPPT algorithm. The modeling of the solar panels is carried out in a Matlab & Simulink simulation environment. The modeling of the adaptive MPPT P&O method is also performed. The tested arrangements are of the Total Cross-Tied (TCT), Total Cross-Tied (SP-TCT), Bridge-Linked - Total Cross-Tied (BL-TCT), Bridge-Linked-Honey-Comb (BL-HC), plus a Magic Square (MS) equivalent for each of the arrangements presented. Magic Square is a way to rearrange the solar panels in different positions, in order to mitigate the losses caused by shading. The performances of all configurations are tested for different shading situations and demonstrated from V-P graphics. In addition to the MS, in order to make the system more efficient, it implements the adaptive MPPT P&O that has a faster response time than the standard P&O.

15
  • ADRIANA BENÍCIO GALVÃO
  • Collaborative Tool for Data Analysis in Public Health: Application in the Time Series Study for the Project "Syphilis No"

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • KENIO COSTA DE LIMA
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Aug 16, 2019


  • Show Abstract
  • Nowadays, there is a trend towards the use of data analysis in order to implement changes in health systems, which allow, among other benefits, cost reduction, disease prevention and better service delivery to the population. One of the initiatives of the Brazilian government, in this sense, is the project "Syphilis No", which induces actions aimed at the control of syphilis in health care networks.     The term "Big Data in Health" has been widely used in several studies that seek, in general, to find and evaluate the possible benefits of Big Data for health care. Many of these studies, however, are based on theoretical and qualitative analysis, presenting limitations in the validation of the proposed solutions and highlighting the skills in the development of competences for the use of Big Data technologies. In this context, the present work has the objective of elaborating and implementing a collaborative tool, which facilitates the analysis of big data, which will contribute, in particular, to the study of time series regarding the reports of acquired, congenital, and registered syphilis in the Notification of Injury Information System (SINAN).

        A framework was developed that allows collaboration between professionals with different skills to develop experimental data analysis programs using a preconfigured big data environment. The framework and its implemented functions make up the tool developed in this work, which allows to import time series and execute methods for the extraction of characteristics involving data from one or more Health Information Systems. Finally, through the tool developed, epidemiological indicators were obtained for the monitoring of Syphilis.
16
  • MARCELLA ANDRADE DA ROCHA
  • A text as unique as fingerprint: The use of intelligent systems for authorship recognition

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • ELOIZA DA SILVA GOMES OLIVEIRA
  • KARILANY DANTAS COUTINHO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Aug 16, 2019


  • Show Abstract
  • The Authorship Attribution, the science of inferring an author for a particular text based on their writing characteristics is a problem with a long history. In this work, it is being proposed the study of the problem of attribution of authorship in order to make it a tool of use in the distance teaching platform of the Ministry of Health (MS), AVASUS, and will be presented the techniques of analysis of text and authors' stylistic characteristics that allow authorship to be determined in significantly better indexes, in which the texts are greater than 140 characters. This proposal targets AVASUS, where students take the courses of the platform, share their interests and thoughts in the form of messages in the forums and do activities that require writing on certain topics in the area of health, these written productions are the focus of the application of attribution of authorship. The techniques studied as a proposal are a two-stage process, where in the first stage, stylometric information is extracted from the collected data set and in the second stage different classification algorithms are trained and lexical analysis techniques are applied to predict the authors of the texts. The effort is to maximize the accuracy of predictions with optimal amount of data and users under consideration. 

17
  • LUÃ SILVA CARDOSO
  • Virtual Impedance Concept to Decouple P/Q of Distributed Generation Systems. 

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • CECÍLIO MARTINS DE SOUSA NETO
  • JOSE RENES PINHEIRO
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Aug 30, 2019


  • Show Abstract
  • The distributed generation systems based on renewable sources has increased due to environmental problems caused by non-renewable sources, fast return on investment and advances in interconnection systems. In Brazil, the distributed generation energy capacity is growing. Before a new electric power system model, distributed generation systems participation, methods to regulate the power flow in generation units can directly contribute to electric system stability, especially in low-voltage grids, which is the predominantly resistive and the active power can cause overvoltages. In addition, power flow strategies used in conventional generation systems cannot be used in low-voltage systems due to active and reactive power coupling. In this work is proposed the power flow control adjust in a distributed generation photovoltaic system controlled in voltage mode based on virtual impedance concept. In order to overcome the active and reactive power coupling problem, the proposed method is implemented by means a virtual resistor. For analysis purposes, the virtual resistor is implemented by two ways. In the first one, a positive virtual resistor is implemented to accentuate the resistive profile of the system, performing the P/V and Q/θ control. In the second one, a negative virtual resistor is implemented in order to make the network profile predominantly inductive, and then perform the traditional P/θ and Q/V control. The virtual impedance concept technique is evaluated through simulation and experimental results.

18
  • MARCOS SÉRGIO RODRIGUES LEAL
  • FPGA-Based Real-Time Power System Simulation for Traveling-Wave-Based Protection Validation

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • MARCELO AUGUSTO COSTA FERNANDES
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • WASHINGTON LUIZ ARAUJO NEVES
  • Data: Sep 6, 2019


  • Show Abstract
  • In this work is proposed a real-time digital simulator of power systems using a low-cost custom platform based on FPGA (field-programmable gate array) proper to perform real-time validation of traveling-wave-based transmission line protections. The operational view of the simulator is introduced by means the modeling, implementation, and simulation steps of a transmission system, which is used to highlight the simulator capability to represent high-frequency transient phenomenon taking place transmission lines. Hence, at first, the mathematical models of the power system used in the case study are presented as well as the solver design, which is developed based on the electromagnetic transients program (EMTP) proposed by Dommel. Then, the simulator characteristics, such as the hardware architecture, development software, communication strategies, graphical interface, input/output, and data export, are introduced, as well as the implementation stages of the test system. Moreover, it addresses the implementation of a relay prototype using a hardware based on DSP (digital signal processor), running a traveling-wave-based protection scheme, besides its closed-loop integration with the simulation.  A GUI (graphical user interface) is developed to set the simulation parameters, including the conditions for applying an electrical fault, and to monitor the dynamic of power system used as a case study. Off-line simulations obtained from Matlab/Simulink are used to validate the real-time results.

19
  • VICTOR HUGO FREITAS DE OLIVEIRA
  • Application speedup characterization: modeling parallelization overhead and variations of problem size and number of cores

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • CALEBE DE PAULA BIANCHINI
  • CARLOS AVELINO DE BARROS
  • EDSON BORIN
  • Data: Sep 13, 2019


  • Show Abstract
  • To make efficient use of multi-core processors, it is important to understand the performance behavior of parallel applications. Modeling this behavior can enable the use of online approaches to optimize throughput or energy, or even guarantee the desired Quality of Service (QoS). Accurate models would avoid having to probe different runtime configurations, which causes extra overhead. Throughout the years, many speedup models were proposed. Most of them based on Amdahl’s law or Gustafson’s law. However, many of those make considerations such as a fixed parallel fraction, or a parallel fraction that varies linearly with problem size, and inexistent parallelization overhead. Although such models aid in the theoretical understanding of parallel computing, these considerations do not hold in real environments, which makes the modeling unsuitable for accurate characterization of parallel applications. The model proposed in this dissertation estimates the speedup taking into account the overhead caused by the parallelization and the variation of the parallel fraction according to problem size and number of cores used. Using ten applications from the PARSEC benchmark suite, the proposed model was able to estimate speedups more accurately than other models in recent literature. Tests were made in two servers, each one with a different hardware architecture.

20
  • YURI IOHANSSEN RIBEIRO DAMASCENO
  • Control Strategy for Soft Transition Between Grid-Connected and Islanding Modes Applied for Low-voltage Distributed Generation Without Energy Storage System

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • CECÍLIO MARTINS DE SOUSA NETO
  • RODRIGO PRADO DE MEDEIROS
  • Data: Oct 4, 2019


  • Show Abstract
  • The world energy demand is expected to rise in the coming decades. Renewable Energy Source Distributed Generation (RES-DG) is being used to meet this increased demand. RES-DG systems can serve local loads on an isolated system (islanded operation) or connected to the power grid (grid-connected operation). Ideally, RES-DG systems should have the ability to transition smoothly between modes so that a continuous supply of power is achieved regardless of the grid state. This work proposes a communication-less control strategy for a low-voltage RES-DG system capable of operating in islanded as well in grid-connected mode and of achieving a smooth transfer between modes. An energy storage system is not required for operation in islanded mode since the energy balance is maintained by acting in the power generated by the RES. The proposed control strategy is divided in three parts: (a) the VSI control, which constitutes the inner control loops of the Voltage Source Inverter (VSI) (current, voltage and power control loops), (b) mode-related control loops (DC link, voltage at the PCC and DG system angular frequency control loops) and (c) the synchronization and islanding detection methods. The control strategy is validated through simulation of a three-phase RES-DG system. The proposed strategy presents a smooth transition between modes, with little to no perturbation on the PCC voltage, and a fast synchronization process from islanded to grid-connected mode. In addition, it also presents a fast DC link voltage control response time that is capable of maintaining the transitory small, even for large power imbalances during mode transition.

     

21
  • DEYVID LUCAS LEITE
  • Channel characterization using Unmanned Aerial Vehicle

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • PABLO JAVIER ALSINA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Oct 31, 2019


  • Show Abstract
  •  

    The use of Unmanned Aerial Vehicle (UAV) to provide services such as internet, goods delivery and air taxi has become a reality in recent years. The use of these aircraft requires secure communication between the control station and the UAV, a task made easier by knowing the characteristics of the communication channel. This work is intended to present a measurement setup using an unmanned aircraft, and to use the measured data for RF channel characterization. Control ground. The collected data were analyzed in order to characterize the large scale fading (path loss and shading) and the small scale fading (multipath and Doppler) in Caatinga scenarios, flight over a lake and a region mixed with the two previous environments. The following work presents the data collected in the measurement campaigns, the processing performed by the developed scripts and the results of the RF Channel characterization.


22
  • MYCHAEL JALES DUARTE

  • ANALYSIS AND DESIGN OF 2.5D AND 3D STRUCTURES OF FREQUENCY SELECTIVE SURFACES FOR APPLICATIONS IN MODERN WIRELESS COMMUNICATION SYSTEMS

  • Advisor : VALDEMIR PRAXEDES DA SILVA NETO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • FRANCISCO DE ASSIS BRITO FILHO
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 12, 2019


  • Show Abstract
  • This work presents a study on Selective Frequency Surfaces (FSS) 2,5 D and 3D, for applications in modern wireless systems. Initially, 2.5D, patch-like structures are analyzed. The simple FSS are formed by elements in square and spiral turns based on the Minkowski fractal. The use of the fractal curve resulted in a miniaturization of the circuit, the appearance of a new transmission band and a decrease in bandwidth. The 2,5D FSS are formed from the simple structures that, for the formation of their elements, the coils were sectioned in eight parts, where four were printed on the upper face of the dielectric, four on the underside of the dielectric and were connected with cylindrical jumpers of 0.5 mm in diameter. The 2.5D surfaces provided miniaturization of the circuit without the appearance of new transmission bands and without decreasing the relative bandwidth. All HSS were stable with respect to the angle of incidence of the plane wave on the surface of the circuit. The simulated numerical results for the projected prototypes were obtained by Ansoft HFSS software. The prototypes were constructed and the experimental measurements of the transmission coefficients were performed, the values obtained were compared and discussed with the results of the simulations, which showed good agreement.

23
  • CARLOS YURI FERREIRA SILVA
  • Implementation of a neural velocity estimator in a three phase induction motor

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALBERTO SOTO LOCK
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE ALVARO DE PAIVA
  • Data: Dec 16, 2019


  • Show Abstract
  • The three phase induction motor is the most used type of machine for electric drives. Low cost, construction simplicity and reliability are the motives that explains this statement. Nowadays, this motor is also highlighting for it's applicability in the automotive area, with the electric vehicle ascension which, besides being a economic alternative to fuel consumption compared to ordinary vehicle, are also a solution for the emission of polluting gases to the environment. From this scenario, the objective of this work is to perform the speed control of an induction motor without the use of a mechanical sensor attached to the rotor, avoiding some inconveniences such as a periodic maintenance and increased complexity and number of equipment are always part of the engine running. For the induction motor control was applied the control strategy known as Field Oriented Control and for the estimation of the motor rotor speed was used an artificial neural network, which observer electrical and mechanical system variables. The practical results were satisfatory, since the neural network worked as both observer and speed estimation and it was possible to perform the control os the motor with the estimated speed in the range of 100 to 170 rad/s.

24
  • JOÃO ALEXANDRE DA SILVA NETO
  • Using Metamaterial Resonators to Improve Planar Filter Performance

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • IRADILSON FERREIRA DA COSTA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Dec 26, 2019


  • Show Abstract
  • This work proposes the insertion of Complementary Split-ring Resonators (CSRR) in the planar filter ground. The intention is to improve some filter parameters found in the literature that have practical application, considering the growing demand for higher performance, smaller size, lower weight and cost of the devices that integrate the communication systems. The filters chosen were a bandpass filter that uses matrioska geometry for applications in the 2.45 GHz Industrial Scientific and Medical (ISM) band. The other filter was a low pass filter for digital TV applications. The idea is to insert the CSRR into the structure ground plane to increase the free attenuation of the matrioska band-reject filter and to reduce the size of the low-pass filter. In the work the numerical and experimental results are presented, for the purpose of validation of the proposed technique. A good agreement between the results is observed, these results show that the proposals presented were achieved.

Thesis
1
  • PATRIC LACOUTH DA SILVA
  • Research and Development of a New Synthesis Technique of Microwave Active Planar Circuits

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • HERTZ WILTON DE CASTRO LINS
  • JOSE ALFREDO FERREIRA COSTA
  • LAERCIO MARTINS DE MENDONCA
  • Data: Mar 14, 2019


  • Show Abstract
  • The work developed in this thesis has as main objective to contribute to the development
    of reconfigurable structures through the application of optimization techniques inspired
    by bee swarm behavior. The main structures studied are planar microwave antennas
    and frequency selective surfaces both for use in systems requiring frequency reconfiguration capability. We present new structures obtained with the classical algorithms and with the modified algorithm developed during the thesis. Simulated and measured results are obtained certifying the accuracy of the projects developed.

2
  • DÊNIS KEUTON ALVES
  • Real-time estimation of power and impedance estimation of the grid through the stationary packet wavelet transform

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • EDSON HIROKAZU WATANABE
  • FLAVIO BEZERRA COSTA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • PAULO FERNANDO RIBEIRO
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Apr 23, 2019


  • Show Abstract
  • The estimate of power quality indices has as primary goal provides to the monitoring systems (measurement, control, protection, etc.) information about proper levels of voltage and power quality. Besides power quality monitoring strategies, the knowledge of the grid impedance is fundamental importance to the understanding of the deviation of the electric power quality indices, providing relevant information to control and stability of the power system. In this context, in this thesis, it proposes the application of the stationary discrete wavelet packet transform (SDWPT) to estimate effective voltages and currents, as well as primary power quantities (active, total apparent, nonactive power, and power factor), and distortion power. Additionally, the analysis tools of signal processing developed in this work allowed the development of a method for estimating the grid impedance. The SDWPT provides a uniform frequency band and possesses the timeinvariance property, which is ideal for power estimation and grid impedance estimation in the real-time. The method of estimation of power quality indices was assessed and compared to the IEEE Standard 1459-2010 under different operational scenarios, where stationary synthetic waveforms and with both stationary and nonstationary power quality disturbances were emulating in an experimental setup. Regarding the grid impedance estimation, the current study was developing to identify the impedance of low voltage electric grids interconnected with distributed power generation systems. The primary goal is providing parameters to delimit the threshold of system instability in terms of the penetration level and identify islanding conditions. The validation of the proposed method was accomplished in a microgrid whose distributed generation is implemented through the photovoltaic plant of 8 kWp connected to the point of common coupling of a three-phase feeder composed by a transformer of 15 kVA. 


3
  • DIEGO HABIB SANTOS NOLASCO
  • Fuzzy Hierarchical Architecture with Additional Deffuzufication Leyer and Applications to the Power Quality Diagnosis 

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • DANTON DIEGO FERREIRA
  • DENIS VINICIUS COURY
  • EDUARDO SILVA PALMEIRA
  • FLAVIO BEZERRA COSTA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Apr 30, 2019


  • Show Abstract
  • Among various existing decision-making methods, hierarchical fuzzy methods have
    emerged as a suitable tool for dealing with complex applications which have many input
    variables and a high degree of subjectivity. In this context, the product of electric
    energy stands out. In general, the diagnosis of energy quality is a difficult practice due
    to the subjectivities inherent to the analysis process, nuances among different standards
    existing in the world, and uncertainties of evaluation parameters. This thesis proposes a
    new methodology for the power quality diagnosis based on the hierarchical fuzzy theory
    with a cascade-type architecture. The proposed method analyzes the quality parameters
    in steady-state electrical systems based on different existing standards in the world and
    performs a linguistic/quantitative diagnosis in which the contributions of the analyzed indices
    are weighted on the power quality of the evaluated system. Firstly, the diagnosis
    method was implemented from two hierarchical fuzzy architectures known (conventional
    and defuzzification free). Posteriorly, a new proposed architecture with additional
    defuzzification of layers was developed to aggregate the main advantages of conventional
    and defuzzification free in order to make the diagnosis method more complete and
    robust. This study proposes that the output of each subsystem obtained from primary
    decision-making process is transferred directly between the hierarchical layers, without
    loss of linguistic information, to obtain a resultant power quality diagnosis. In addition,
    a secondary decision-making process is performed together with an additional defuzzification
    method in order to obtain a complementary specific diagnosis at the out of each
    hierarchical subsystem. The diagnosis method based on the proposed fuzzy architecture
    presented satisfactory results when compared with the two existing architectures. After
    validation of the diagnosis method and hierarchical fuzzy architecture, both presented in
    this thesis, at the end of research, an adaptive wavelet-fuzzy system with generic inference
    method based on extended overlap functions is proposed as a new tool able of monitoring
    the power quality in renewable energy systems.

4
  • DANILO DE SANTANA PENA
  • Localization based on Acoustic Signals subject to Impulsive Noise 
  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • WALTER DA CRUZ FREITAS JÚNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: May 14, 2019


  • Show Abstract
  • The acoustic channel has received much attention in recent years due to many applications and some emerging technologies. As a result, researchers have considered realistic acoustical channels for studying of the source localization methods. Therefore, this work presents an approach of time difference of arrival (TDOA) for the impulsive acoustic channels based on non-linear data transform. The TDOA methods are evaluated in different scenarios using synthetic and real data. Moreover, the non-Gaussian impulsive noise models are analyzed in the various environment with measurement using an experimental setup.
5
  • PAULO CÉSAR LINHARES DA SILVA
  • Daubechies Wavelets Application in Conjunction with the Vectorial Beam Propagation Method in the Analysis of Photonics Structures.  

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ANTONIO RONALDO GOMES GARCIA
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • Data: May 24, 2019


  • Show Abstract
  • Wavelets are mathematical tools that allow the decomposition, description or representation of a given function. Among the various types of wavelets, Daubechies has a peculiar property of having the compact support, which allows describing the behavior of functions with discontinuities or abrupt variations of values in frequency and/or time domain. It is possible to obtain its coefficients, integrals, and derivatives by means of numerical procedures. In this context, the propagation of signals in devices that propagate electromagnetic waves can be numerically analyzed with the aid of these types of wavelets. In this work, we use the Daubechies wavelets as base functions for joint application with the Beam Vector Propagation Method (VBPM). In this case, these functions are obtained by means of the change in the translation and resolution of the wavelets and by the use of the moment generating function, obtained as part of this study. From the obtained wavelet base, an algorithm was developed to calculate elementary matrices, specific to the VBPM, which is based on the finite element (FEM) method. As a convergence test of the VBPM with the new set of base functions obtained in this work, we analyzed the wave propagation in an electromagnetically coupled guide and the transfer of energy between a conventional optical fiber (COF) and a near-photonic crystal optical fiber (FQCF).

     

6
  • KENNEDY REURISON LOPES
  • Expert System for Industrial Environment Based on Self-Learning Rules

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • GILBERT AZEVEDO DA SILVA
  • OSCAR GABRIEL FILHO
  • Data: May 24, 2019


  • Show Abstract
  • This work presents a methodology of how to acquire and represent knowledge through automatic logic rules for a simulated industrial plant. The initial knowledge about an industrial process can be acquired through a specialist who interprets situations present in the plant and can describe what is occurring. In the work, a way of acquiring statistical knowledge of the plant during the execution of its processes is presented, using a method of online clustering known as TEDA-Cloud being modified to improve performance. The representation of knowledge is described through the manipulation of a neural network known as CILP and its own symbology is described to represent the logical variables drawn from the process signals. The results show an efficiency in interpreting the rules and acceleration in the process of clustering and classifications of the standards that define the rules.

7
  • ANDRÉ NASCIMENTO DA SILVA
  • New Techniques for the Impedance Matching Optimization of Printed Antennas for Wireless Communication Systems

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • EVANDRO CONFORTI
  • FRED SIZENANDO ROSSITER PINHEIRO
  • JOABSON NOGUEIRA DE CARVALHO
  • LAERCIO MARTINS DE MENDONCA
  • Data: May 27, 2019


  • Show Abstract
  • The work presented in this dissertation consists in the development of new techniques for the impedance matching optimization of printed antennas for wireless communication systems. The techniques proposed are based on the insertion of slots in the antenna feeding line or below it (in the ground plane), enabling to keep unchanged the patch geometry of the investigated microstrip antenna. The study was performed using a parametric analysis and enabled the development of three new impedance matching techniques. In the first, the insertion of the slot is carried out in the conducting strip of the microstrip line, being symmetrically placed. In the second, the slot is introduced into the ground plane but it is inserted below and parallelly to the conducting strip of the microstrip line. In the third, the slot is also positioned in the ground plane, but is aligned parallel to the lower edge of the conducting patch, i.e. perpendicularly to the conducting strip of the microstrip line. The effect of the input impedance matching on the performance of rectangular patch microstrip antennas printed on glass fiber substrates (FR-4) was investigated. The antennas were fed by microstrip lines and designed for operation at 1.8 GHz, 2.45 GHz, and 3.5 GHz. Simulation and parametric analyses were performed using Ansoft Designer and HFSS softwares, that implement the method of moments (MoM) and the finite element method (FEM), respectively. In addition, the wave concept iterative procedure (WCIP) was also used in the analysis, enabling a better comparison between the obtained simulated results. For validation purpose, several prototypes were fabricated and measured. The good agreement observed between simulated and measured results confirms the efficiency and accuracy of the new impedance matching techniques. The proposed techniques are easy to implement and allow considerable reductions in the reflection coefficient value, | S11 | (dB), indicating that the antenna efficiency was significantly increased. In the first case, for the slot inserted in the conducting strip of the microstrip, the value of | S11 | (dB) was reduced from -8.81 dB to -28.09 dB in the analysis for 2.45 GHz. In the second case, for the slot inserted in the ground plane, below and parallel to the conducting strip of the microstrip, the value of | S11 | (dB) was reduced from -7.62 dB to -37.17 dB in the analysis for 2.45 GHz. In the third case, for the slot inserted in the ground plane, parallel to the lower edge of the conducting patch, the value of | S11 | (dB) was reduced from -10.11 dB to -34.1 dB in the analysis for 1.8 GHz. The use of slots, as proposed in this work, enabled a good impedance matching between the antenna and the microstrip feeding line, avoiding the use of high impedance microstrip lines, abrupt transitions in the width of microstrip lines, changes in the shape of the antenna conducting patch, or increasing the antenna size. The proposed optimization techniques present an excellent potential for applications in the development of other microwave integrated circuits, such as filters, power dividers, and directional couplers, in planar technology.

8
  • JAN'' ERIK MONT'' GOMERY PINTO
  • PLC Implementation of Piecewise Affine PI Controller Applied to Industrial Systems with Constraints

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • FABIO SOARES DE LIMA
  • OSCAR GABRIEL FILHO
  • Data: May 31, 2019


  • Show Abstract
  • In this work the design of a piecewise affine proportional integral (PWA-PI) controller algorithm based on invariant set and multiparametric programming for constrained systems is proposed. We implemented the algorithm in a programmable logic controller (PLC) to control an industrial constrained level plant and analyze its behavior. Structured text routines were programmed and validated while controlling two systems with PLC. The results show that the constraints on the error, integral of the error, system output and control action are respected because PWA-PI controllers are tuned from the solution of an optimization problem. The evaluated performance indexes (such as mean square error, Goodhart,  overshoot and settling time) show that PWA-PI can be adjusted for better performance than proportional integral (PI) controller tuned by Ziegler–Nichols (Z–N) rules. In the analyzed cases, a settling time of 108 s was obtained, whereas PI controller with Z–N rules presented a 179 s settling time. All of the analyzed performance indexes that we used to evaluate both controllers show PWA-PI as a better controller for constrained systems.

9
  • MARCELO DAVID SILVA DE MESQUITA
  • SYNTHESIS OF A NEW CONDUCTIVE INK FOR MICROWAVE PRINTED CIRCUITS ON GLASS AND FIBERGLASS SUBSTRATES

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • JEFFERSON COSTA E SILVA
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • MARIA THEREZA MIRANDA ROCCO GIRALDI
  • Data: May 31, 2019


  • Show Abstract
  • This thesis describes the work carried out for the synthesis of a new conductive ink, with high concentration of silver particles, and the investigation on the possibility of its use in the manufacture of integrated circuits for wireless communication systems. The use of the new conductive ink is proposed as an alternative to the use of conventional microwave integrated circuits manufacturing techniques. The great interest in the use of conductive ink is associated with the ease, efficiency, versatility and reduction of manufacturing costs of the integrated circuits, provided by the use of small paint brushes for the application on different dielectric materials. The conductive ink obtained from the synthesis of nitrocellulose, which, in ethyl acetate solution, acts as a bonding agent of the pigment (silver metallic powder) to form a conductive film, one of the contributions of this work. The synthesized conductive ink was used in the development of microstrip antennas, bioinspired frequency selective surfaces (FSS), DC blocks, and directional couplers. The last two microwave integrated circuits were developed using parallel coupled microstrip lines. The simulation and design of these circuits were performed using Ansoft Designer and Ansoft HFSS softwares. In the analyses, glass and fiberglass substrates, very thin conductive plates made out of copper and silver, and surfaces painted with silver ink were considered. The frequency behavior of the scattering parameters of these circuits were investigated, enabling the evaluation of different aspects related to the transmission, reflection, coupling, radiation, and electromagnetic wave filtering. In order to validate the simulation results and to compare the measurement results, prototypes of microstrip antennas were fabricated and measured on fiberglass substrates with a copper laminate and with a surface painted with conductive ink. Also, prototypes of microstrip antennas were manufactured on glass substrate. The measurement of the reflection coefficient and the input impedance of these antennas were performed using a network analyzer. In the case of FSSs, prototypes were simulated and manufactured with elements inspired on the leaf of the Oxalis triangularis plant on fiberglass substrates, with copper clad laminate and surfaces painted with the synthesized conductive ink. The transmission coefficient measurement of these FSSs were performed using a network analyzer and two horn antennas. In the cases of DC block and directional coupler, prototypes were simulated on fiberglass substrates, with copper clad laminate and with surface painted with conductive ink, providing the opportunity to investigate the effect on the electromagnetic coupling between the painted parallel microstrip lines. The measurement of the reflection and transmission coefficients of these circuits were carried out using a network analyzer. The good agreement observed between the simulated and measured results for the microwave integrated circuit prototypes painted with silver ink confirms the efficiency and versatility of the painting procedure with the synthesized conductive ink.

10
  • TIAGO FERNANDO BARBOSA DE SOUSA
  • Equalization and Beamforming Proposals for Modern Communication Systems

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • JOSE PATROCINIO DA SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • DALTON SOARES ARANTES
  • TOKTAM MAHMOODI
  • Data: Jun 7, 2019


  • Show Abstract
  • This work aims to present new proposals for equalization and beamforming associated with modern digital communication systems. Three proposals are presented in which the first is characterized by an innovative neural equalizer structure called here the Butterfly Neural Equalizer (BNE). The BNE can be applied to linear and non-linear problems involved in intensity-modulated and direct-detection (IM-DD). The second proposal is characterized by an adaptive beamforming scheme applied to Orthogonal Frequency-Division Multiplexing (OFDM) systems. The OFDM technique and variants are being used in various communication systems such as LTE, digital TV, and others. Finally, the third proposal presents a neural beamforming structure called Butterfly Neural Beamforming (BNB) that can be applied to several communication systems. Results associated with the three proposals are presented and show the feasibility of the techniques in several channel scenarios and digital modulation schemes.

11
  • AYLANNA RAQUEL DA COSTA OLIVEIRA
  • Analysis of relief functions to estimate branch loadings after Corrective Switchings

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • CLOVIS BOSCO MENDONCA OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • MELINDA CESIANARA SILVA DA CRUZ
  • Data: Jun 29, 2019


  • Show Abstract
  • There are several studies proposing Corrective Switching technique for eliminating overloads in transmission branches. Some proposed Corrective Switching algorithms are based on electrical circuits theory or Relief Function methodology. This work presents a new linear methodology that proposes to compare the results obtained from the execution of a Relief Function applied to Corrective Switching technique in contingency cases with the results of other methodologies previously developed and with the load flow tests in transmission systems. This Relief Function has been determined analytically and it is based on a Two-ports network model. When carrying out the studies throughout this Thesis, contingencies were created from line disconnections in the studied transmission systems - this alteration occasionally caused multiple branch overloads in the electric network, but they were analyzed one at a time. Another step is to verify the nonlinearities of the switching measures: to analyze if the electric quantities obtained from the application of a linear technique can present great variations with respect to the obtaining from a nonlinear model, meaning, an exact load flow, and to comprehend the influence that certain parameters present in the estimated loadings can exert on the nonlinearity of these operation maneuvers. It is important to emphasize that the new network topology can be identified quickly, since the calculations necessary to estimate the new load are linear, which requires little computational effort. This enables an on-line application to find a feasible solution in Energy Management Centers.

12
  • IGOR GADÊLHA PEREIRA
  • Dynamic Synchronization of Distributed Multimedia Systems Using Machine Learning

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDERSON ABNER DE SANTANA SOUZA
  • COSIMO DISTANTE
  • GUIDO LEMOS DE SOUZA FILHO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Jul 1, 2019


  • Show Abstract
  • The exchange of multimedia data streams in a distributed scenario represents a challenge mainly because of two problems generally present in this context: the synchronization between several streams and the management of heterogeneous hardware present in the system. The difficulty in maintaining the time limits necessary for the reproduction of time-dependent multimedia data stream increases with disturbances introduced by the communication channel, which is directly related to the quality of service. On the Internet, streaming real-time multimedia data requires efficient synchronization and storage strategies, which can add a significant amount of latency and interfere with the end-user quality of experience (QoE). Among the applications that require low latency to ensure an acceptable QoE, the composition and reproduction of songs through the Internet represent the biggest challenge. Towards this direction, we propose an effective method for low latency synchronization of several streams in a distributed global multimedia network, such as the Internet. Throughout the experiments we made to verify our proposed systems, we identified good accuracy levels on the synchronization of audio and video streams. We specifically emphasize the accuracy levels of 72% for the synchronization of video streams and up to 93% for the synchronization of raw audio sequences. In order to achieve these results, we employed statistical analysis of superior order and neural networks, both convolutional and recurrent, to compute a time relationship between multimedia flows.

13
  • ELIEL POGGI DOS SANTOS
  • Development of a numerical technique for the analysis of frequency selective surfaces of the type absorb-transmitt.

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • MAURICIO WEBER BENJÓ DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jul 18, 2019


  • Show Abstract
  • Modern wireless communication systems use various types of devices such as antennas, modulators, filters, detectors, absorbers and many other types for the most diverse applications emerging in the field of telecommunications. In particular, electromagnetic wave absorbers have become critical components in security, detection and imaging systems. The fundamentals of the absorbers are based on configurations that allow the control of the absorption of electromagnetic waves and that by increasing the performance requirements of microwave absorption, good performance in civil applications and the emergence of new types of materials absorbers of microwaves, attracted considerable attention from the researchers resulting in considerable progress.

    In this sense, the full-wave methods and numerical methods are usually used for the analysis of several parameters in the telecommunications structures. They are used in many cases in the core of commercial software as well as in hybrid methods. The use of simpler numerical techniques allows an analysis of reflection and transmission behavior in a suitable way with good approximation mainly in cascade structures.

    In this work the absorber structure is composed of a conductive frequency selective surface (FSS) and a resistive FSS in which there is a d spacing between the FSS. The conductive FSS is formed by a FR4 dielectric with an electric permittivity of 4.4 and the geometries formed by conductive copper strips. Resistive FSS have an FR4 dielectric with an electrical permittivity of 4.4 and the geometries are formed by OhmegaPly 1A50PT (35 micron - 50 ohms / sq) resistive materials.

    The thesis proposal is to develop a numerical technique for the analysis of integrated microwave absorbers to selective surfaces in frequency. A model was used for conductive FSS and one for resistive FSS both using the equivalent circuit technique based on the Marcuvitz equations and for analysis of the set or cascade of the structures, the scattering matrix technique was used. Attempts have been made to use other techniques, however, this combination has resulted in better results. Internal parameters of the method such as coefficients, resistance, inductive and capacitive reactances of the geometries were analyzed in order to allow a better approximation with respect to the simulations and measurements.

    The designed absorbers used cross-dipole geometry and square loop both designed and measured in the laboratory. The numerical analysis technique showed good agreement with the measured and simulated results of the author's own structures as well as with other measured and simulated absorbers presented in the literature. Improvements and modifications can be tuned for other applications, integrate with optimization techniques, hybrid algorithms and other projects of periodic structures.

14
  • EMANOEL RAIMUNDO QUEIROZ CHAVES JUNIOR
  • Strategies for Fault Estimation in Actuators and Sensors in Non-Linear Processes with Uncertainties.
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • MARCELO ROBERTO BASTOS GUERRA VALE
  • OSCAR GABRIEL FILHO
  • Data: Jul 26, 2019


  • Show Abstract
  • Over the years, control processes have become more complex, containing a large number
    of components that work in an integrated manner. Any of these components is subject
    to defects or malfunctions. All these factors are defined as faults, which are unexpected
    variations of the properties of a given component to its nominal operating condition. The
    consequences of failures may cause economic losses and risk the life of the workers in
    the enclosure. A fault tolerant control system is able to keep the control process running
    with proper performance even in the presence of failures. In its active approach, the nominal
    control strategy is reconfigured so that the effect of the fault is accommodated. This
    reconfiguration is usually based on the estimate of the fault, which is obtained by means
    of an observer. Generally the effectiveness of an observer is related to the degree of knowledge
    about the process by the designer. An unforeseen change in system parameters
    or the presence of uncertainties may adversely affect the performance of the observer.
    This work proposes two state observer design techniques which are able to perform the
    simultaneous estimation of states and faults in actuators and sensors in nonlinear systems
    in discrete time with uncertainties. The operation of this method is verified by means of
    computational simulations based on case studies involving crane, liquid level processes
    and control of a flexible articulated robotic manipulator.

15
  • BETOVEN OLIVEIRA DE ANDRADE
  • Analysis and Design of Microstrip Patch Antennas  with substrate PBG printed 3D

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • HUMBERTO DIONISIO DE ANDRADE
  • WELLINGTON CANDEIA DE ARAUJO
  • Data: Jul 26, 2019


  • Show Abstract
  • After a few decades of the first publications on microstrip antennas, research continues to expand. This is the consequence of several of its attractive features, especially the possibility of mounting in the same plane of the transceiver circuits. However, this advantage presents some problems - the waves produced by the circuits reflect and refract inside the substrate, since it has different refractive indices, which causes surface currents in the earth plane, leading to a narrow bandwidth and also to lower radiation efficiency and low gain, since some of the energy is wasted. In order to attenuate such negative characteristics, several techniques have been investigated and employed, one of the most promising being the use of PBG (Photonic Band Gap) substrates. PBGs are periodic structures in a dielectric or conductive material. They propagate the electromagnetic waves at a frequency specific to all states of polarization and angles of incidence. In this thesis, it is proposed an adequate methodology to study new structures and techniques aimed at the use of PBG material in the form of three-dimensional periodic (3D) holes in the substrate in the manufacture of microstrip patch antennas for the range between 1 to 4 GHz. This thesis presents some contributions, as described below: (i) proposition of new antennas, including antennas with printed substrates (3D); (ii) theoretical development of coherent antenna design, avoiding resonance frequency shifts, caused by changes in the permittivity after insertion of the holes; (iii) demonstration that different hole geometries are not related to resonance frequency variation; (iv) analysis that an unconventional geometry can promote large efficiency improvements in computational design time; (v) applying an artificial neural network capable of substantially improving the time to obtain the return losses; (vi) proposition of low-cost techniques for the development of antennas with PBG substrate. In order to validate the proposed antennas, simulations and measurements are presented and discussed.

16
  • ÍCARO BEZERRA QUEIROZ DE ARAÚJO
  • Maximum correntropy criterion applied to structure selection and parameter estimation of NARX models

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • JOILSON BATISTA DE ALMEIDA REGO
  • EVANDRO DE BARROS COSTA
  • JOSE BEZERRA DE MENEZES FILHO
  • Data: Jul 26, 2019


  • Show Abstract
  • In the last decades, due to the growing complexity of dynamic systems and the growing demand for better performance, the area of systems identification has emphasized the use of non-linear models to represent dynamic systems. In this context, Non-linear autoregressive with exogenous inputs models (NARX) are heavily used due to to their simplicity, flexibility and capacity of better representation. However, such models rely heavily on structure selection and the most traditional algorithms have limitations when the data is contaminated by non-gaussian distribution noises. Noting this, in this thesis, the objective is to present a new identification method called simulated correntropy maximization with pruning which uses concepts of learning based on information theory. In this work basic concepts about systems identification and correntropy, methods based on orthogonal least squares and simulated error reduction, and the new proposed methodology. The proposed method is applied and compared to the traditional methods in some study cases. The first experiment is composed by three SISO numeric dynamic systems in the presence of bimodal noise. The second study case is a set taken from a benchmark system called Silver Box. The third is a real dynamic system. The fourth and last one is a real dynamic MIMO coupled-tanks system. The obtained results validate the performance of the proposed method when compared to other algorithms of structure detection and parameter estimation, showing that the proposed method presents a better and more robust performance in the presence of non-gaussian distribution noise.

17
  • CLÁUDIO PEREIRA DA COSTA
  • Analysis of New Topologies of CPS, SIEW and FSS-EBG Filters for Wireless Communication Systems

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • JOABSON NOGUEIRA DE CARVALHO
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Jul 30, 2019


  • Show Abstract
  • The objective of this thesis is to present the analysis of new topologies of CPS, SIEW and FSS-EBG filters for wireless systems applications. The coplanar stripline (CPS) structure consists of two conducting strips loaded by two split ring resonators (SRRs), forming a CPS filter. The SIEW filter is based on the integrated E-plane waveguide substrate technology, being composed of several dielectric layers stacked with two resonant elements inside it, enabling selectivity with horizontal polarization. The third filter configuration consists of two periodic arrays formed by an FSS and an EBG, composing an integrated structure. The investigation of these structures was carried out by numerical analysis of the frequency response due to the variation of the physical parameters of the investigated geometries, identifying the attractive potentialities for microwave applications. The simulated results were obtained with the commercial software Ansoft HFSS and exhibited attractive characteristics as: reconfiguration, wide bandwidth, double band, simple design, light weight and easy manufacturing on a large scale. Some prototypes of the proposed devices were manufactured and the experimental results confirmed the validity of the used computational models. The experimental results were also compared with the simulated results, exhibiting a good agreement between them.

18
  • JOÃO PAULO FERREIRA GUIMARÃES
  • Complex Correntropy: Definition, Properties and Applications

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ADRIAO DUARTE DORIA NETO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO VON BORRIES
  • ALUISIO IGOR REGO FONTES
  • Data: Sep 30, 2019


  • Show Abstract
  • Recent studies have demonstrated that correntropy is an efficient tool for analyzing higher-order statistical moments in non-Gaussian noise environments. Although corren- tropy has been used with complex data, no theoretical study was pursued to elucidate its properties, nor how to best use it for optimization. By using a probabilistic inter- pretation, this work presents a novel similarity measure between two complex random variables, which is defined as complex correntropy. It’s properties are studied as well as a new recursive solution for the Maximum Complex Correntropy Criteria (MCCC) and two algorithms are derived, one based in the ascendent gradient and a second one on a fixed-point solution. Simulations were made in order to evaluate how the robust this new measure is to impulsive noise in different problems: liner system identification, chan- nel equalization and in a compressive sensing problem. It is also shown the application of complex correntropy as a tool to analyse the similarity between angles. The results demonstrate prominent advantages of the proposed method when compared with the clas- sical algorithms from the literature.

19
  • ITALO AUGUSTO SOUZA DE ASSIS
  • Intra-node and Inter-node load balancing and other scalable approaches for high-performance seismic processing

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • JOAO MEDEIROS DE ARAUJO
  • JORGE DANTAS DE MELO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • REYNAM DA CRUZ PESTANA
  • SAMUEL XAVIER DE SOUZA
  • Data: Oct 14, 2019


  • Show Abstract
  • Seismic modeling, reverse time migration (RTM), and multi-scale waveform inversion (MFWI) are three of the most important techniques in seismic surveying. Seismic modeling simulates the wave propagation, RTM generates an image of the subsurface, and MFWI produces a wave propagation velocity model. These methods demand intensive computational cost due to a large amount of data they process and the complexity of their algorithms. Because of that, they are only implemented for parallel systems in practical. Although there are efficient parallel implementations of modeling, RTM, and MFWI in the literature, further improvement can be achieved by better exploring the parallelism in these methods and the characteristics of the current parallel systems. This research proposes coupled multi-scale waveform inversion (CMFWI), an alternative method to MFWI, which improves parallel scalability by reducing the parallel dependency between the processing of different frequency content of the data. An implementation of CMFWI using the coupled local minimizers method (CLM) is presented. L2-norm results showed that CMFWI had an inferior performance when compared to MFWI. These experiments indicate that further research is necessary to implement CMFWI as it compares data with different frequency contents. This work also introduces an auto-tuning strategy for properly choosing the optimal chunk size that reduces the runtime of a 3D RTM algorithm in shared memory systems. A coupled simulated annealing method (CSA) is employed to adjust the chunk size of work that parallel loops assign dynamically to worker threads. Experiments show that the proposed method is consistently better than two default OpenMP loop schedulers being up to 44% faster. This thesis also introduces the cyclic token-based work-stealing (CTWS) for distributed memory systems. The novel cyclic token approach reduces the number of failed steals, avoids communication overhead, and simplifies the victim selection and the termination strategy. Results obtained by applying the proposed technique to balance the workload of a 3D RTM present a factor of 14.1% speedup and reductions of the load imbalance of 78.4% when compared to the conventional static distribution. Finally, an implementation of a 2D visco-acoustic modeling is presented.

20
  • DANIEL GUERRA VALE DA FONSECA
  • Explicit Formulation for Generalized Predicitve Control: a Multiparametric Approach

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • PERICLES REZENDE BARROS
  • Data: Oct 30, 2019


  • Show Abstract
  • Generalized Predictive Control (GPC) is one of the most traditional and popular Model-based Predictive Control (MPC) techniques in industry and academia and has been applied over decades in several systems to improve the control performance. Among the application areas, GPC can be found in petrochemical, energy, food, automotive and aerospace. This type of controller uses process model information to predict future system behavior. The prediction is made by minimizing a functional cost that produces optimal control actions capable of leading the controlled variables to the desired values. In addition, GPC can deal directly with both MIMO systems and process constraints. However, when considering the constraint set, the controller needs to solve a Quadratic Programming (QP) in real time, which can be prohibitive in certain cases, such as for embedded systems. This work uses multiparametric programming (mp) to generate an Explicit Piece-wise Affine (PWA) control law for GPC (mp-GPC) which holds the same control performance without the need to keep solving the optimization problem at each sample time. Hence, initially, the proposed formulation is compared with GPC based on online QP. The results show that the performance is maintained, reducing the computational time to calculate the control action. Then, a new format is proposed, which differs from the last one by the amount of parameters needed in the mp formulation. Both propositions are applied in three different situations: a MIMO system, a process with input-output delays and a underactuated system. A comparison is made by checking the computational time spent to calculate the control signal, as well as the time required for mp resolution. Finally, studies were initiated involving a Hybrid Multiparametric GPC formulation, which makes use of the resolution of a multiparametric Mixed-Integer Linear Programming (mp-MILP). A nonlinear valve is used as a case study, in which its nonlinear characteristics are treated as discrete dynamics for the optimization problem, in order to minimize its effects. Preliminary results are satisfactory, however, tests on real applications need to be done in future works.

21
  • VIRGINIA PINTO CAMPOS
  • System for Automatic Audio-description Generation from Video Content Analysis

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • BRUNO MARQUES FERREIRA DA SILVA
  • NEY ROBINSON SALVI DOS REIS
  • TIAGO MARITAN UGULINO DE ARAUJO
  • Data: Nov 28, 2019


  • Show Abstract
  • Audio description is an accessibility feature designed to make visual information accessible to blind or low vision people. To increase the range of audio description tracks in digital video applications, we propose a system for automatic audio description generation of movies. The system can use as source of information about the film the original script or the video itself. As a proof of concept, we developed a prototype that automatically generates audio description based on actions taken from the script and objects recognized in the video. The experiments contemplated the application of the solution in fiction films and surveillance videos. For fiction films, an evaluation was made with blind people. The results indicated that through the automatic audio description generated by the solution, it was possible to provide contextual information that can help the user in the general understanding of the story. For surveillance videos, a performance evaluation was made using the delay time of each component. Results indicate that a solution has the potential to be used in contexts that require real-time AD.

22
  • THALES AUGUSTO DE OLIVEIRA RAMOS
  • An Efficient System of Electric Machines for Wind Power Generation driven by an Electromagnetic Frequency Regulator

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE TAVARES DE OLIVEIRA
  • JOÃO PAULO ABREU VIEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • PAULO VITOR SILVA
  • RICARDO FERREIRA PINHEIRO
  • Data: Nov 29, 2019


  • Show Abstract
  • A new topology has recently been developed to drive generators to enable hybridization of two power sources. Particularly, if one of these sources is wind power, it also serves the purpose of avoiding power electronic devices directly connected to the grid. The system consists of a squirrel cage rotor induction machine and a rotational armature with a three-phase winding that is powered by a secondary source. This new machine frame has been named the Electromagnetic Frequency Regulator (EFR). The objective established in a first research was to convert a variable speed imposed by the wind turbine to the armature, in a constant speed to be developed by the cage rotor, driving a synchronous generator shaft. A first objective of this Thesis was to mathematically model the topology and simulate it inserted in a large wind turbine. Then, it was proposed to use an induction generator instead of a synchronous generator, aiming to find the maximum extraction point of available wind power. From steady state analyzes, two possible control systems are proposed: a scalar control, which aims to obtain a desired speed for the system rotor, and a control that aims at the strategy of obtaining the maximum possible efficiency for the REF. Permanent regime simulations are performed in order to compare the two control systems presented. Thus, it is verified that the control by maximum efficiency strategy obtains better results when compared with the correspondents obtained from the scalar control. Dynamic simulations performed for the two proposed topologies show that both are viable and support variations in wind speed and disturbances in the power grid.

23
  • HEITOR MEDEIROS FLORENCIO
  • Analytical Model of Link Stability in Industrial Wireless Sensor Networks.

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRES ORTIZ SALAZAR
  • DANIEL LOPES MARTINS
  • DENNIS BRANDAO
  • JORGE DANTAS DE MELO
  • Data: Dec 9, 2019


  • Show Abstract
  • Wireless Sensor Networks (WSN) have emerged in the industrial environment with the purpose of increasing flexibility and deploying measurement and actuation elements in hard to reach areas. However, due to the peculiarities of wireless communication in the industrial environment, the use of metrics to evaluate the performance of communication links is crucial. An essential factor in assessing network behavior is the stability of links. The stability is a property, but several studies define the stability model using different parameters of the link. This thesis presents an analytical model of link stability based on received signal strength and packet delivery rate. The results obtained through tests performed with different scenarios showed that the analytical model can identify link installability situations when it comes to high variation in received signal strength and low packet delivery. Then, an ISA 100.11a network control system was developed to validate the model proposed in this work. The results obtained with the application of the model in the level control system presented steady state error values below the predetermined maximum limit, while in the control tests that did not consider the link stability factor the error exceeded the limit.

24
  • MISSILENE DA SILVA FARIAS
  • State Feedback Type-2 Fyzzy Rule-Based Applied to Nonlinear Systems Servocontrol

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE BEZERRA DE MENEZES FILHO
  • OSCAR GABRIEL FILHO
  • WALLACE MOREIRA BESSA
  • Data: Dec 9, 2019


  • Show Abstract
  • Many researches use T-S fuzzy models to accurately represent nonlinear dynamic systems. However, T-S fuzzy makes the implementation of fuzzy controller more complex as system order and nonlinearities increase. Thus, the present work is aimed to overcome these limitations by using an Interval Type-2 Fuzzy Rule-Based System in which the membership functions and the number of rules can be freely chosen simplifying the implementation of the technique. To this end, it is established a direct state feedback control with reference tracking to generate the nonlinear control action using parallel distributed compensation techniques with no need to include T-S fuzzy models to describe the dynamic system. The proposed strategy is applied to a synchronous generator and also to a magnetic levitation system. From the results, it was verified that SBRF T2Is are able to stabilize the systems analyzed at different equilibrium points with higher performance and less settling times, given the uncertainties in the linearized model. In fact, the SBRF T2I proved to be a proper way to accomplish this task, because fuzzy logic control itself does not depend on an accurate model.

25
  • ISAAC BARROS TAVARES DA SILVA
  • Development of NiFe2O4 Ferrimagnetic Material for Application in Microwave Communication Systems

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOABSON NOGUEIRA DE CARVALHO
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • MARCELO DAVID SILVA DE MESQUITA
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Dec 16, 2019


  • Show Abstract
  • Due the need to develop new wireless technologies, the researches involving communication devices has become intense, mainly in characteristics like device miniaturization and reconfigurability. With this objective, this work presents a proposal for the development of ferrimagnetic compounds aiming their application in wireless communication devices. The project was performed starting at the nickel ferrite (NiFe2O4) through Sol-Gel modified by ICR technique. A calcination process was applied to eliminate organic compounds from Sol-Gel, as the large particle size production, over 300 nm. The calcination was performed at 1100 °C, for ten hours, with 10 °C/min step. The obtained particles were characterized by SEM, XRD and EDS. Magnetic behavior (hysteresis loop) was also obtained, as complex electric permittivity parameter. All performed morphological characterization were applied in a study of Sol-Gel process efficiency, according to nitrate concentration on chitosan matrix. The nitrate concentration was modified to verify which concentration promote better process efficiency, so that 120 g/L concentration could be verified as the more suitable for a high-quality product. Posteriorly, one of the proposed devices was manufactured: ferrite powder encapsulated with low permittivity wood material, aiming FRA application. Electric characterization was performed in all four types of applied woods. Reflection coefficient was determined and discussed. Then, ferrite bulk materials were manufactured using a 15-ton uniaxial press with propanone binding agent, followed by heating process before sintering. This process was performed with same temperature parameters of the powder production, aiming to not change microscopical characteristics. Electric characterization of ferrite bulk was performed and its application as microstrip patch antenna substrate and FRA was verified. Magnetic permeability was estimated based on previous papers characterization of NiFe2O4 powder. With electric characterization, simulations of FRA, with three different types of excitation, and proposed antennas was performed by HFSS software, using FEM method and the reflection coefficient was experimentally determined to validate the simulations. The experimental results presented good agreement with all performed process of production and characterization, reaching a 0.82% error in resonance frequency based on simulated results. The nickel ferrite potential as FRA and microstrip patch antenna is evidenced along the results discussion, being possible to expand the applications possibilities in other electrical engineering fields.

26
  • FRANCISCO SALES DE LIMA FILHO
  • Smart Defender: A DoS / DDoS Attack Detection and Mitigation System Using Machine Learning

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • PAULO SERGIO DA MOTTA PIRES
  • GENOVEVA VARGAS-SOLAR
  • PLACIDO ANTONIO DE SOUZA NETO
  • Data: Dec 20, 2019


  • Show Abstract
  • Denial of service (DoS) attacks, and their distributed variant (DDoS), represents one of the most significant risks to the availability of services operating on the Internet. This cyber threat continues to grow worldwide and is detrimental even as network protection technologies advance. Developing mechanisms that can detect and mitigate the impacts of malicious traffic generated by DDoS attacks is a current challenge in network security, with a direct impact on the lives of the world's population. This paper proposes the Smart Defender system as a solution, consisting of Smart Detection (SD) and Smart Protection (SP) tools that operate in an integrated and distributed manner. The proposed detection system makes inferences based on pre-existing signatures using Machine Learning (ML) techniques to classify network traffic. The protection system, in turn, applies rules to control useless traffic and mitigate the effects of DDoS, considering the information shared by the detection system and the security policy of the local network. In the experiments performed, modern reference data sets and semi-controlled laboratory environment tests were used. The results show that the proposed solution is capable of early detection of high hit rate and low false alarm rate DDoS attacks, as well as isolating the threat in the first minute of attack.

27
  • ANDERSON COSTA SILVA DOS SANTOS
  • System to assist installation and maintenance of control-focused industrial wireless networks

     

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • DANIEL LOPES MARTINS
  • DANIELLE SIMONE DA SILVA CASILLO
  • JORGE DANTAS DE MELO
  • Data: Dec 27, 2019


  • Show Abstract
  • Nowadays, wireless communication has aroused interest and is a tendency in industry environments. In part this interest is due to the ease of deployment and maintenance of this network, which dispenses sophisticated designs and execution of works of deploying cables, which in industrial environment often prohibitively expensive, and enabling the addition of new applications when compared to their wired counterparts. Despite its high degree of applicability, a wireless network faces some technical (reliability, energy consumption, environment interference) and cultural challenges present as the main negative points for the deployment of large-scale industrial networks in the industry. To reduce some these problems, this work presents a system with multiobjective modeling to aid installation and maintenance of devices - sensors and actuators - in industrial wireless networks, allowing the use of controllers in these networks, with emphasis on WirelessHART and ISA100.11a standards, which presents themselves as the most promising solution for industrial wireless networks.

2018
Dissertations
1
  • BRUNO SÁTIRO DA SILVA
  • Complementary Frequency Selective Surface (CFSS): Concept and Design

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Jan 24, 2018


  • Show Abstract
  • Wireless communication is an integral part of modern society, having fundamental role in the process of globalization and technological development. Therefore, several researches are carried out in order to achieve constant optimization in this area. Frequency Selective Surfaces (FSS) have been approached for decades because of its telecommunications functionalities. Due to evolution of technology, new demands arise every day with specific answers for each application, thus, the FSSs need to be modeled to meet the most diverse requirements. In this context, the present work aims to show a specific model of FSS. The Complementary Frequency Selective Surfaces (CFSS) have very interesting characteristics for modern communication systems, such as multi-band frequency behavior, high selectivity in transmission bands and great angular stability, being useful in a wide range of applications, such as aircrafts, radomes and satellite communication. As part of this work, new unit-cell geometries for CFSS will be proposed and analyzed, comparing the simulated results with those of constructed prototypes and indicating possible applications.

2
  • WINNIE DE LIMA TORRES
  • Detection of Vocal Deviations Using Auto Regressive Models and the KNN Algorithm

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • ADEMAR GONÇALVES DA COSTA JÚNIOR
  • Data: Jan 30, 2018


  • Show Abstract
  • Some fields of science propose to study disorders in the vocal tract from analyzes on patterns of vibration of the voice. In general, the importance of these researches is to identify, in a more specific stage, diseases of greater or lesser severity, to be healed with vocal therapy or that require more attention, even generating the need for surgical procedures for its control. Although there are already indications in the literature that digital signal processing allows non-invasive diagnosis of laryngeal pathologies, such as vocal diseases that cause edema, nodule and paralysis, there is no definition of the most indicated method and the most characteristic features or parameters to detect the presence of vocal deviations. Thus, in this work an algorithm is proposed for the detection of vocal deviations through the analysis of speech signals. To perform this work, we used constant data in the database Disordered Voice Database, developed by the Massachusetts Eye and Ear Infirmary (MEEI), due to its use in research in the acoustic area of voice. We used 166 signals contained in this database, with signs of healthy voices and pathological voices affected by edema, nodule and paralysis in the vocal folds. From the voice signals, Auto Regressive models (AR and ARMA) were generated to represent these signals and, using the parameters of the obtained models, the KNN algorithm was used to classify the analyzed signals. In order to analyze the efficiency of the algorithm proposed in this study, the results obtained from this algorithm were compared with a detection method considering only Euclidean distance between the signals. The results show that the method proposed in this work presents a good result, generating a rating rate above 71% (greater than 31% from the use of Euclidean distance). In addition, the method used is easy to implement and can be used in simpler hardware. Therefore, this research has the potential to generate an inexpensive and affordable classifier for large-scale use by health professionals as a non-invasive pre-analysis alternative for the detection of otorhinolaryngological pathologies that affect the voice.

3
  • PEDRO YOCHINORI GUSHIKEN
  • Second Level Adaptation as a Parameter Estimation Technique and its Application to Model Reference Adaptive Control

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • JOSENALDE BARBOSA DE OLIVEIRA
  • FRANCISCO DAS CHAGAS DA SILVA JÚNIOR
  • Data: Jan 31, 2018


  • Show Abstract
  • Adaptive control is used when there is parametric uncertainty in the controlled system. There are two distinct strategies: direct and indirect. Direct adaptive control estimates the controller parameters in real time. In indirect adaptive control the plant parameters are estimated in real time through an identification model and these estimates are used to calculate the controller parameters. There are several identification models that can be used such as parallel, series-parallel and linear regression models. There are several parameter estimation methods that can be used to update these models that are suitable to be used in conjunction with indirect adaptive control such as the least squares method and normalized gradient method. In this context a new method for parameter estimation based on multiple identification models was recently proposed, known as second-level adaptation. In second level adaptation the estimates of the plant parameters are obtained by convex combinations of the estimates from multiple identification models. The coefficients for these convex combinations are also estimated, as a second level of adaptation. In this dissertation we demonstrate the concept of second level adaptation as a parameter estimation method for the case of a plant of degree unity, the case of a plant of degree n with single input and output available for measurement (SISO) and the case of a plant of degree n with p inputs whose state vector is available for measurement (MIMO). We propose a modified form of the adaptive law for second level adaptation. In all cases simulation studies show that the estimates reach their true values faster with second level adaptation compared to individual identification models and that the proposed modification is even faster and also smoother in this regard. Finally, we apply second level adaptation based on linear regression identification models updated through the normalized gradient method to the problem of model reference adaptive control(MRAC) of a degree n SISO plant with relative degree one. The closed-loop stability of the system is demonstrated. Simulation results show that the control signal generated with second level adaptation yields better results of model reference tracking compared to individual identification models.

4
  • ISAAC DANTAS ISIDÓRIO
  • Variable Structure Adaptive Pole Placement Control for Supression of Chaos in the Lorenz System

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • CAIO DORNELES CUNHA
  • ODAILSON CAVALCANTE DE OLIVEIRA
  • Data: Jan 31, 2018


  • Show Abstract
  • Two main methods highlight for the design of adaptive controllers: the model reference adaptive control (MRAC) and the adaptive pole placement control (APPC). In MRAC, a reference model is chosen to generate a trajectory, which must be followed by the output of the plant to be controlled. This type of project may involve cancellation of the plant zeros, not applicable to non-minimum phase plants. APPC, in turn, is considered the most general type of adaptive control, presenting a design methodology for the controller and adaptation law quite flexible, besides not involving  plant zero-pole cancellations. The combination of the conventional adaptive methods, that use integral adaptive laws, with variable structure systems (VSC) based in switching laws, allows to aggregate fast transient and robustness to disturbances and parametric uncertainties. In this context, based on a class of pole placement control schemes (PPC), the variable structure adaptive pole placement control (VS-APPC) arises. Here, such as in APPC, the control law is generated for the case with known parameters (transfer function coefficients), replacing them by their estimates. The estimation process identifies the adaptive method used, so that APPC uses integral laws while the VS-APPC makes use of switching laws. In this work is proposed, based on the variable structure adaptive pole placement control theory, a control system able to control the chaos phenomenon in Lorenz system, using only the measured plant's output and input variables. The parameters of system are considered unknown and is considered the disturbance presence in input system. It is shown that in closed-loop system, the output tracks the reference trajectory and the state vector converges to the equilibrium state, presenting good transient behavior and robustness to the parametrics uncertainties as also in presence of disturbance in input plant.


5
  • HUGO RAFAEL GONÇALVES CAVALCANTE
  • Acquisition of frequency in low-orbit satellite by maximum correntropy criterion.

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • SAMUEL XAVIER DE SOUZA
  • ALUISIO IGOR REGO FONTES
  • JOSÉ MARCELO LIMA DUARTE
  • Data: Feb 16, 2018


  • Show Abstract
  • Low-earth orbit (LEO) satellites move at very high speeds and can circumscribe the planet several times in a single day. These high dynamics environments induce considerable Doppler shift and Doppler rate values in spatial communications signals, which is known as dynamic Doppler shift. Establishing communication with these systems is a multi-task process and, due to the dynamic Doppler shift, a critical task is the fine acquisition of the carrier frequency. Several studies have investigated frequency estimation techniques of satellite signals, considering communication environments characterized by additive white Gaussian noise (AWGN). However, the effects of impulsive noise should also be considered in a more accurate characterization of the LEO satellite communication scenario. This work introduces a new method of frequency acquisition for low-orbit satellites based on similarity calculus by maximum correntropy criterion. Due to some of its properties, correntropy is very efficient in the processing of non-Gaussian signals, especially in impulsive noise environments. It was investigated the robustness of the technique proposed in this work on a communication environment characterized by impulsive noise, and compare its performance with that obtained by a classical approach, based on the correlation coefficient. The carrier frequency acquisition method for LEO satellites proposed in this work can be used in the development of a decoder for signals from the Brazilian Environmental Data Collection System (SBCDA) and Franco-American Envi-ronmental Data Collection System (ARGOS).

6
  • RAFAEL FERREIRA ALVES DE ASSIS
  • Design of a NTC Thermistor-Based Thermal Anemometer with Linearized Feedback Model

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • DIOMADSON RODRIGUES BELFORT
  • JUAN MOISES MAURICIO VILLANUEVA
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Jun 1, 2018


  • Show Abstract
  • The velocity or volumetric flow measurement of laminar or turbulent flow meet various engineering applications. Thus, scientific research for the development of architectures and measurement techniques for these quantities is of great relevance and is constantly expanding. Among the existing architectures for anemometric applications in an indistinct flow regime, thermal anemometers denotes several advantages such as excellent bandwidth, spatial resolution and low cost. This is basically a thermistor connected to one of the arms of a modified Whetstone bridge. Although it has simple configuration, it has some limitations imposed by the non-linear relation between the temperature and the quantity applied to the sensor. In addition, it contributes as a limiting non-ideality of the operational amplifier that makes up the architecture. Therefore, it is proposed the design and implementation of a thermal anemometer architecture with linearization of the relation with the temperature by voltage feedback and using a thermoresistive sensor of the NTC type. We also promote comparisons between the classic anemometer and the one proposed in this work. For this, the validation of the proposed architecture is conducted through simulations, as well as experimental comparison with classical and other instrument

7
  • CARLOS EDUARDO DE BARROS SANTOS JÚNIOR
  • Proposed implementation of MD5 and SHA-1 hashes algorithms on reconfigurable hardware

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIANO MAURO CANSIAN
  • CARLOS EDUARDO DA SILVA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • MARCELO AUGUSTO COSTA FERNANDES
  • VALENTIN OBAC RODA
  • Data: Jun 20, 2018


  • Show Abstract
  • This work proposes two Application Specific System Processor (ASSP), one to the MD5 algorithm and other to the SHA-1 algorithm implemented on Field Programmable Gate Array (FPGA) Xilinx Virtex 6 xc6vlx240t-1ff1156. The throughput and the occupied area were analyzed for several implementations on parallel instances of those algorithms. The results showed that the hardware proposed for MD5 achieved a throughput of 0.8 Gbps for a single instance and slightly more than 140 Gbps for 320 instances in a single FPGA. Already for the SHA-1 algorithm, it has achieved a throughput of the 0.644 Gbps for a single instance and a little more than 28 Gbps for 48 instances on a single FPGA. Several applications such as password recovery, password validation, and high volume data integrity checking can be performed efficiently and quickly with an ASSP for MD5 and SHA-1. This work also presents a comparative analysis of the energy consumption associated with execution of the MD5 and SHA-1 algorithms for three different hardware platforms, a microprocessor (uP) of 8 bits and 32 bits and the specific application hardware designed for each algorithm. Results of consumption estimation from the processing time (measured in the laboratory) show that the use of dedicated hardware presents significant gains in energy savings.

8
  • TAIANE VIANA DE CARVALHO
  • Data Clustering Methods Applied to Image Segmentation

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ALLAN DE MEDEIROS MARTINS
  • ALUISIO IGOR REGO FONTES
  • PABLO JAVIER ALSINA
  • Data: Jun 28, 2018


  • Show Abstract
  • Due to the great technological advance,  the computer is increasingly being used to extract information in images. Segmentation is one of the most main and complex process in  image processing. This paper presents a new technique of images automatic segmentation based on textures through a clustering application method. This method is composed of a set of distinct techniques and divided into two steps. The first step uses vector quantization to group the data set (pixels) in auxiliary centers and the second step group the auxiliary centers that have more common properties in a single group.  The main differential of this proposal is the use the method Quadratic Renyi’s Negentropy Separation (QRNS) which creates a hierarchical structure between  groups found. Validation of the method is performed with different images and its performance compared to other methods.

     

9
  • CAMILA NASCIMENTO DOS SANTOS
  • Image processing system for computing Transfer Function using Mason formula

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • PABLO JAVIER ALSINA
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ALUISIO IGOR REGO FONTES
  • Data: Jun 28, 2018


  • Show Abstract
  • Several daily activities utilize complex control systems. Many of these require the users, skill and time for their representation. These systems can be modeled and represented in the form of signal flow diagrams to represent the causal relationship between their components. One method used to calculate the equivalent Transfer Function (FT) of a diagram is the Mason Formula. This requires that all paths be found, and if this does not happen, the calculated final FT is incorrect. 
    The objective of this work was to describe an image processing system, which is able, from a hand drawn diagram, to obtain the final transfer function more efficiently. Where from a hand-drawn signal flow diagram, a directed graph is automatically obtained, which represents the drawing with all the direct paths and loops present. The developed tool was shown to be able to help students and professionals correctly calculate the final FT for a given diagram, following the proposed conditions.
10
  • WERBET LUIZ ALMEIDA DA SILVA
  •  
     
    Automation of a Pilot Plant for Flow  Estimation in Multizoned Injection Wells from Temperature Profiles.
  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • CARLA WILZA SOUZA DE PAULA MAITELLI
  • JEFFERSON DOOLAN FERNANDES
  • Data: Jun 29, 2018


  • Show Abstract
  • A pilot system was built at the Laboratório de Avaliação de Medição em Petróleo (LAMP) to evaluate estimation methods of flow distribution in wells by heat transmission models. In this work, it is intended to develop an automation system with a sensor structure, actuators and a monitoring software, to control the variables needed to the process simulation of water injection in multizones. Equipment to be used: flow, level and temperature sensors, and actuators like valves and pumps, all connected to a programmable logic controller by WEG, model: TPW03 60HT-A, that will be able to concentrate the data and communicate with a monitoring system implemented in Elipse SCADA software. This structure will acquire data to evaluate the flow estimation method from temperature measurements throughout the simulated injection tubing. The flow sensors will allow the comparison of the measured and estimated values with the mathematical model. It's intended to make adjustments in the original designed structure and to repeat the experiments in order to reduce the measurement uncertainty obtained in previous tests.
11
  • ANDRÉ LUIZ AGUIAR SOUSA
  • Multivariable Fuzzy System Applied to the Control of the Composition of Liquefied Petroleum Gas

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRE LAURINDO MAITELLI
  • JOSE MEDEIROS DE ARAUJO JUNIOR
  • Data: Jul 2, 2018


  • Show Abstract
  • In the present work, artificial intelligence techniques were applied in a simulated natural gas processing plant, composed of two distillation columns, a deethanizer column and a debutanizer column. In this process, the background product of the deethanizer, known as LGN, is supplied to the debranching column, where it is fractionated. The lighter components are evaporated giving rise to LPG (Liquefied Petroleum Gas), while the heavier fractions, denominated of C5+, remain in the liquid state. Ideally, LPG is composed only of butane and propane, but in practice this is not the case, since contaminants such as pen- tane and ethane are always present. In this work it is proposed to simultaneously regulate the amount of pentane and ethane in the LPG composition by means of the dynamic gene- ration of set points (SP) for the present controller’s layer of the instrumentation known as regulatory control. For this, a multivariate fuzzy system is used that will adjust the values of these SPs, from the comparison of the molar fraction of pentane and ethane present at the exit of the plant (LPG) and its desired quantities. The columns were simulated in the HYSYS® chemical process simulation software designed with real characteristics of the columns present in the Natural Gas Processing Unit, located in the municipality of Guamaré-RN.

12
  • FÁBIO RICARDO DE LIMA SOUZA
  • Identification and Control of Dynamic Systems using Fuzzy Wavelet Neural Network

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE MEDEIROS DE ARAUJO JUNIOR
  • Data: Jul 3, 2018


  • Show Abstract
  • Mathematical modeling is a task of vital importance for the development of science and technology, since its objective is to obtain a mathematical description of a real phenomenon. Regardless of their nature, real systems need to be studied and their dynamics must be known in order for their functioning to take place as desired. The classical way of obtaining a mathematical representation is by analyzing the physical laws governing systems. However, in this case, in addition, they are (often) difficult or even impossible to follow this path, and a plausible alternative is the identification of systems. The identification of dynamic systems aims to obtain a mathematical representation of the dynamics of a system based on input and output data. Real dynamic systems are ultimately nonlinear. In some applications, as linear approximations are sufficient, however, when linear representations do not express a dynamic process, it is necessary to use a nonlinear model. In the last decades, as neural networks have been installed as one of the main tools for an identification of nonlinear dynamic systems, as they have characteristics that make them attractive for identification, due to nonlinearity and generalization and learning. From the possession of a model that satisfactorily represents the dynamics of a system, it can be used for applications such as control, prediction, inference, among others. The present work proposes the application of a Fuzzy Wavelet Neural Network in the identification of nonlinear dynamic systems. This hybrid technique combines the multiresolution features of the Wavelet theory with the learning ability and the generalization of the neural networks together with the ability to deal with Fuzzy logic uncertainties. The obtained model is used for the tuning of a PID controller. In the course of the work, the concepts and techniques necessary to perform identification and controller tuning will be presented. The results obtained attest to the efficiency of the technique used.

13
  • DANIEL RODRIGUES DE LUNA
  • Performance Evaluation of new waveforms for underwater submarine channels

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Jul 5, 2018


  • Show Abstract
  • This master’s degree working plan aims to perform a study on the performance of modulation and multiplexing techniques over submarine acoustic channel. Initially, what is underwater communication and its existing forms of communication is introduced. Then, the main effects that a submarine channel is subject and their respective formulations are presented, as well as the set of models well accepted by the academy, Bellhop models. The work is based on the proposal to using the OFDM and GFDM waveforms as an alternative to the classical waveform used in submarine communications, the FSK. A link simulator was developed and, through it, value-added analyzes are presented for different waveform configurations and channel manifestations implemented. Performance is accessed by means of bit rate error curves for some levels of Eb/N0. Finally, the work produced and its perspectives are presented, elucidating the conformity between the simulation and the theoretical curves, as well as the challenging work that is to transmit in high rate of transmission in the submarine channel.

14
  • HILÁRIO JOSÉ SILVEIRA CASTRO
  • A methodology for hybrid indoor location to mobile systems

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCELO HENRIQUE RAMALHO NOBRE
  • SILVIO COSTA SAMPAIO
  • Data: Jul 9, 2018


  • Show Abstract
  • In recent years, technological development has allowed the emergence of new concepts for new services, among the new proposals the indoor location systems. Since conventional solutions such as the Global Positioning System do not result in good results, several areas encourage the generation of new solutions for location indoor, in order to enhance its services. With the motivation to provide a new solution, will be demonstrated in this work a proposal of methodology of location indoor, able to find the location of the target in a hybrid way in terms of propagation of signals in indoor environments, using the trilateration method, combining with target motion tracking with the use of inertial sensors. Throughout the work are demonstrated all the challenges for generation of the indoor localization methodology, as well as mitigation devices for misrepresentations.

15
  • THALES QUEIROZ FONSECA
  • Enhance Distributed Generator Power Flow Control with an Adaptive
    Variable Structure Virtual Impedance Strategy.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • FLAVIO BEZERRA COSTA
  • JOSE RENES PINHEIRO
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Jul 10, 2018


  • Show Abstract
  • The advances in power electronics and environment restrictions have driven the insertion of renewable energy based systems on power grid. Generally, these generation systems use the solar and/or wind energy as primary source and, mostly, they are connected to the power grid through power electronics converters. The integration of these systems into the grid brings with it some problems, due to its stochastic generation, as instability of the electric power system in which the renewable generation system is connected. Therefore, it is important to use an efficient control system to ensure the proper functioning of the system. A control strategy that has been increasingly used with the increase of the integration of renewable generation systems is the virtual impedance. With the use of virtual impedance in the control strategy there is the possibility to modify the dynamic behavior of converters, changing its output impedance, without presenting additional
    losses to the system. There are several applications with the implementation of
    virtual impedance, such as: power flow control, harmonic and unbalance Compensation, active stabilization, among others. The proposal of this work is the implementation of a control structure in which the output currents and voltages of the inverter are controlled and, with the use of virtual impedance, permits to modify the output power flow of the converter.

16
  • LUIS FELIPE DE VASCONCELOS TORRES DA COSTA
  • ANALYSIS OF CPW AND CPS ANTENNAS AND FSS WITH FRACTAL GEOMETRIES FOR WIRELESS COMMUNICATIONS SYSTEMS


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • JOABSON NOGUEIRA DE CARVALHO
  • LAERCIO MARTINS DE MENDONCA
  • Data: Jul 13, 2018


  • Show Abstract
  • The recent advance of technology on wireless communication systems has increasingly enabled the user to handle different applications. This has attracted great interest among microwave researchers, who work in mobile communications, short-haul links, wireless local area networks (WLAN) and satellite communications, for example. As a result, many researchers around the world are increasingly seeking to improve this technology to develop light, compact and inexpensive devices and equipments to operate in multiple communication services.

    In this context, the development of planar microwave antennas and frequency selective surfaces (FSS) appears as an attractive alternative, due to their intrinsic properties such as small volume, reduced weight, low cost and ease of manufacture, besides allowing operating with different characteristics of radiation and polarization. Usually, planar microwave antennas are developed in microstrip lines and exhibit narrow bandwidth, being designed to operate in particular frequency ranges.

    Recently, there has been a growing interest in the development of planar antennas in other planar transmission lines, among which are the coplanar waveguide (CPW) and the coplanar striplines (CPS). CPW antennas have larger bandwidths than microstrip antennas, and are suitable for the development of broadband antennas. CPS antennas can be used in both microwaves and millimeter waves.

    In addition, there are also many studies being carried out on the development of selective frequency surfaces (FSS), as they act as spatial filters with compact, light, and low cost structures, which allow the transmission or rejection of microwave signals for designed frequency bands.

    On the other hand, the fractal geometries, when used in planar antenna designs, allow the reduction of size and show the multiband behavior. In comparison with conventional planar antennas, the antennas with fractal geometries present lower resonance frequencies, allowing the manufacture of more compact antennas.

    The main objective of this work is the simulation of CPW and CPS structures for the design of new CPW and CPS antennas with fractal elements for operation in the 1 GHz to 14 GHz band, aiming at applications in multiband, wide band and ultra wideband (UWB). In addition, the characteristics of radiation, gain and polarization of the antennas are observed. Computational simulations are performed and several configurations of CPW and CPS antennas and FSS are designed using Ansoft HFSS software. For purpose of comparison with the simulated results, several prototypes of CPW and CPS antennas are manufactured and measured. FSS structures are also designed, simulated and measured. The experimental results show a good agreement with the results of the numerical simulations performed for both antennas and HSS.

17
  • MARCOS TULIO ANTUNES BEZERRA SEGUNDO
  • Analysis of Segmented Optical Waveguide with Quasi-Periodic Sequency

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁDLLER DE OLIVEIRA GUIMARÃES
  • Data: Jul 13, 2018


  • Show Abstract
  • In this work, the Vectorial Beam Propagation Method (VBPM) is applied in the analysis of quasi-periodic segmented waveguides. The structure has an intercalated refractive index along the propagation direction, following the Fibonacci sequence, which in this case is applied in order to reduce scattering losses caused by imperfections in the walls of the guiding region. The VBPM is expressed in terms of the transverse components of the magnetic field, including Perfectly Matched Layers (PML). Some models of dielectric structures will be studied such as: analysis of the rectangular guide of pure silicon immersed in a substrate of silicon dioxide and analysis of the rectangular guide of pure silicon with substrate of silicon dioxide and upper cladding of SU-8, a photoresist material. The study is based on the analysis of propagating transversal modes, power along the guiding region and the chromatic dispersion at the end of the guide. The computational simulation is obtained using the language FORTRAN 2008 in conjunction with the PYTHON programming language.

18
  • YURI MAX VIEIRA BATISTA
  • ANALYSIS OF FRACTAL INSPIRED STRUCTURES APPLIED TO ANTENNAS AND FREQUENCY SELECTIVE SURFACES

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • Data: Jul 13, 2018


  • Show Abstract
  • The development of new fractal-based structures applied to planar technology has motivated many researchers around the world, who are very interested in the design of compact, stable, efficient, and low cost microwave devices and circuits for wideband, ultra wideband, and multiband frequency applictions, with enhanced filtering (transmission or rejection) and radiation (or rejection) characteristics, for example.

    Specifically, the geometry of traditional fractals have been widely used in the development of integrated circuits for microwaves and antennas because they have enhanced their frequency responses. However, in order to extract more advantages from the potential of these geometries, they must be changed according to the particular applications. In addition, due to external interference, spatial filters, such as frequency selective surfaces (FSS), have become increasingly popular with the large growth in the use of wireless technologies, as they appear to be an excellent solution for predetermined frequency filtering.

    In addition, the use of traditional or new fractal geometries in these structures always brings particular contributions in improving their frequency responses. Therefore, the main objective of this work is to improve current FSS technology using known fractal geometries, which are modified, to take more advantage of the use of these geometries’ characteristics.

    Thus, using some different configurations of the same architecture, inspired by the Hilbert fractal, one can configure the structure of the FSS to obtain improved bandwidth, multi-band operations, good angular stability, and compactness, for example. In addition, these fractal-based structures exhibit characteristics to be investigated with respect to the size reduction of the patch element of the periodic array and to the modification of the antennas resonance frequencies.

    Results using a FSS as ground plane in a rectangular patch antenna structure with inset-feed suggest the possibility of significantly decreasing the antenna resonant frequency, as well as the appearance of multiple resonance bands, as if the patch had a fractal geometry. This work compiles the experiment of several fracture-inspired antennas and FSS structures that resonate in different frequencies. Several prototypes are fabricated and measured to validate the simulation results.

    This work presents FSS geometries inspired on the Hilbert fractal, the infinite mirror fractal, and the Sierpinski triangle geometries, with additional modifications to ensure angular and multiband stability. In addition, the developed antennas are inspired on Sierpinski fractal geometries, with Hilbert-inspired ground planes, as well as antennas inspired on the fractal of the image, enabling multiband frequency behavior and miniaturization.

19
  • Danilo Chaves de Sousa Ichihara
  • Nonlinear Model Predictive Control with Adaptive Strategy Based on Parallel Coupled Simulated Annealing

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • CARLOS EDUARDO TRABUCO DOREA
  • SAMUEL XAVIER DE SOUZA
  • TIAGO PEREIRA DO NASCIMENTO
  • Data: Jul 27, 2018


  • Show Abstract
  • Model Predictive Control (MPC) is an advanced control technique that has had a significant impact on process industries. There are several reasons for its great acceptance, e.g., it copes with multivariable control problems naturally, it considers constraints on input and output variables, and adapts to structural changes. Despite the growing research effort focused on the development of nonlinear predictive control strategies, the use of these techniques in real systems is still a challenge, because the developed algorithms are usually more complex and, sometimes, do not allow real-time applications for fast dynamics systems. Nevertheless, the constant increase in the speed and power of computing makes this perspective real. This way, the purpose of this work is to develop a nonlinear predictive control strategy that uses a stochastic optimization algorithm with great parallel scalability known as Coupled Simulated Annealing (CSA). The strategy aims at solving directly, without approximations of the process model, and in a parallel way, the optimization problem associated to nonlinear MPC for real-time applications in fast dynamics systems. As the model used in predictive control is only a mathematical approximation of the plant, there is a possibility of mismatch between their behaviours. Thus, the proposed strategy seeks to meet the requirement of robustness to model uncertainties, solving the problem adaptively. In the present work, the parallel version of CSA was used to solve the constrained control problem in three distinct nonlinear systems: real application in a Coupled Tanks system, simulation of rotary inverted pendulum control and a nonlinear chemical reactor, considering the mismatch between plant and model parameters. The experiments results showed the efficiency and characteristics of the control strategy to control these faster dynamics systems, requiring few adjustments to be applied in the different control problems, besides the advantages of optimizer parameters initialization. The efficiency and characteristics of the adaptive strategy considering the mismatch between model and process are presented to simulate the control of a nonlinear chemical reactor with uncertain parameters.

20
  • DANIEL MARQUES DA SILVA
  • Wavelet-Based Analysis and Detection of Fault-Induced Transients in HVDC Systems

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • JOSSANA MARIA DE SOUZA FERREIRA
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • FELIPE VIGOLVINO LOPES
  • VLADIMIRO HENRIQUE BARROSA PINTO DE MIRANDA
  • Data: Aug 1, 2018


  • Show Abstract
  • A fast and accurate detection of the transients is essential to ensure a reliable protection system capable to act with high-speed. In this work, a theoretical foundation regarding the highvoltage direct current (HVDC) transmission systems and the wavelet transform is provided. Then, a qualitative analysis of the traveling waves induced by faults on direct current (DC) transmission lines of HVDC systems is presented for detecting the wavefronts arrival times using the boundary wavelet coefficients from real-time stationary wavelet transform (RT-SWT). This qualitative analysis takes into account the steady-state and the detection of the inception times of both first and second wavefronts at the converter stations. The behavior of the boundary wavelet coefficients in DC transmission lines is examined considering the effects of the main parameters that influence the detection of the traveling waves, such as mother wavelets, sampling frequency, DC transmission line terminations, as well as fault resistance and distance. An algorithm designed to run in real-time and with self-adaptive criteria is proposed to detect the surge arrival times. Quantitative results were achieved based on the accuracy of one- and two-terminal fault location estimation methods to evaluate the algorithm performance.

21
  • FRANCISCO CANINDE DA SILVA JUNIOR
  • Overhead Transmission Line Protection in Monopolar LCC-HVDC Systems Based on One-Terminal Traveling Wave

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • JOSSANA MARIA DE SOUZA FERREIRA
  • JOSÉ CARLOS DE MELO VIEIRA JUNIOR
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • RODRIGO PRADO DE MEDEIROS
  • Data: Aug 3, 2018


  • Show Abstract
  • In general, the direct current (DC) transmission conventional system lines, systems
    LCC (Line Commutated Converter), presents great lengths, which increase the fault occurrence
    rate and, consequently, the demands on the protection methods. A transmission
    line protection with fast actuation is indispensable, because avoid damage in the system’s
    assets, loss of stability and increase the capacity of electrical energy transmission. Currently,
    the protection methods with potential to become the quickest existing are the traveling
    wave-based methods. In this work, the traveling wave theory and the traveling wave-based
    protection principles are investigates and, at the end, is proposes an one-terminal traveling
    wave-based protection scheme for overhead transmission lines of monopolar LCC-HVDC
    (High Voltage Direct Current) systems. The proposed method is based in the arrival time
    of the first and second traveling waves on just one line terminal. Therefore, presents the
    advantage of not need of a communication system and data synchronization between the
    line ends as required in the two-terminal traveling wave-based methods. The sampling
    frequency impact on the proposed method is considered, which, in general, is not realized
    by the one-terminal traveling wave-based methods. Expressions to determine the
    minimum sampling frequency for that the method works correctly are presented in order
    to avoid excessives sampling rates. In addition, classical problems regarding to the
    one-terminal traveling wave-base methods, such as faults very close to the line ends and
    the traveling wave propagation velocity estimation on the transmission lines, are analyzed
    and solutions to such problems are presented. The proposed methods evaluation is realized
    by means of computational simulations. The results demonstrate the fast action of the
    proposed scheme, the existence of protection zones due to the sampling process and that
    the proposed scheme not need of the knowledge of the traveling wave propagation velocity,
    which makes the method immune to the inaccuracies in the traveling wave velocity
    estimation and independent of the transmission line parameters.
22
  • TOMAZ FILGUEIRA NUNES
  • Statistical Analisys and identification techniques of Baja Pilots

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • MARCELO HENRIQUE RAMALHO NOBRE
  • Data: Aug 31, 2018


  • Show Abstract
  • Immersing in the motorsports context, the system identification becomes a great ally to the racing team efficiency by extracting important features from car/driver system and providing feedbacks for a better performance. From that principle, this work aims to identify drivers of an off-road Baja SAE vehicle. Through the partnership with the Car-Kará Baja SAE UFRN team, four different drivers have been selected in 7 different test tracks. The data has been collected, through an industrial data logger, and analyzed in an offline manner. From the data collection, it has been done a division of the variable vector in 3 and 5 sections and then it has been computed the statistical analysis for each part, creating the feature vectors. That vector was inserted in an artificial neural architecture with two hidden layer, obtaining a success rate of 97% for the division in 3 parts and 93% for 5 parts.

23
  • EVERTON DA SILVA DANTAS
  • Implementation of Virtual Synchronous Machine applied for Grid-tied PV systems.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FLAVIO BEZERRA COSTA
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • CECÍLIO MARTINS DE SOUSA NETO
  • Data: Oct 10, 2018


  • Show Abstract
  • The huge expansion of the systems of electric power generation from renewable sources, highlighting wind and solar sources, gave rise operation challenges to the electrical power system, among which it can be highlighted: an intense variability and difficult predictability of the generated power by means of these resources, and susceptibility while facing a transient disturbance, which may cause instability. Currently, the use of renewable generation systems is possible due to its low representability on the electrical system and the hydroelectric synchronous generator’s capacity in absorbing oscillations from other sources ensuring system stability. The concept of virtual synchronous machine has been used in power electronics systems in order to reduce the oscillations generated from these resources and, consequently, mitigate their effects. This qualification aims to present a proposal of control structures modification of a photovoltaic renewable generation system in order to perform a dynamic behavior similar to a synchronous generator: softening power delivery and mitigate the problems before mentioned.

24
  • TARCIANA CABRAL DE BRITO GUERRA
  • Machine Learning Based Handover Management for LTE Networks with Coverage Holes

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • VALDEMIR PRAXEDES DA SILVA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Dec 18, 2018


  • Show Abstract
  • Legacy strategies have been adapted to fulfill the increasing demand for wireless broadband internet access. One of them, the Hierarchical Cell Structure (HCS), that is already in use in LTE-A and it is considered for the 5G, consists in the deployment of several types small cells under the umbrella of macrocells, creating an overlaid coverages. Due to their low power and bellow-rooftop-level, sometimes indoor base stations, the small cells are severely affected by the surrounding obstacles, making the perceived Quality of Experience (QoE) of the users subject to fast variations, thus rendering ineffective the classical approaches to mobility management, that are unable to predict those severe fading situations (coverage holes). Considering the amount of available information on the network performance and the evolution of real-time processing capabilities, the enhancement of LTE functionalities such as the handover, by means of machine learning algorithms became possible. This work proposes and evaluates the performance of a machine learning based approach to handover in the presence of signal-blocking obstacles. Our machines learn from experience and they are, therefore, able to choose the eNB that will most likely offer the user the highest long term QoE after the handover procedure, even in severe propagation conditions. The performance evaluation shows that the proposed schemes substantially improves the user's QoE.

Thesis
1
  • JOSÉ LUCAS DA SILVA PAIVA
  • Implementation of EBG Structures in Microstrip Antennas and Linear-Circular Polarization with metasurface for WLAN

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO DIONISIO DE ANDRADE
  • JOSE PATROCINIO DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁDLLER DE OLIVEIRA GUIMARÃES
  • Data: Jan 30, 2018


  • Show Abstract
  • Faced with the broad utilization of wireless communication system and of their application in frequency band WLAN (Wireless Local Area Network), the present work aims to analyze the behavior of microstrip antenna, projected in configurations of structures with resonator ring (SRR), complementary resonators (CSRR) and electromagnetic band gap (EBG). These elements are inserted periodically under the patch in the substrate of antennas and developed for frequency bands WLAN – bands reserved in the development industrial, scientific and medical (2.45 GHz and 5.85 GHz). Thus, the study is based on include elements, that improves the performance of the electromagnetic parameters, to the structure of the microstrip antenna. Posteriorly, applies to the antennas proposals to the metasurface model with cell simplified, so as to provide capability to convert the linearly polarized signals, generated by a microstrip antenna in circularly polarized signals, obeying their range of operation projected. The numerical analysis of the structures is by means of Ansoft HFSSTM, and to validate these results, the structures will be characterized experimentally.

2
  • IVAN MAX FREIRE DE LACERDA
  • Magister – Methodology for Analysis of Distance Education Programs based on Learning Analytics

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • AKYNARA AGLAE RODRIGUES SANTOS DA SILVA BURLAMAQUI
  • ELOIZA DA SILVA GOMES OLIVEIRA
  • FRANCISCO MILTON MENDES NETO
  • Data: Mar 2, 2018


  • Show Abstract
  • This work proposes a methodology for the analysis of distance learning programs, based on learning analytics technology with the data of the students access to the Learning Management System (LMS) identifying the most frequent sequential patterns of use and classifying them according to the categories of self-regulated learning. For the sequential data mining the SPAM and VGEN algorithms was applied to the databases of two educational institutions. In addition to development of the methodology, as a result of this processing, a higher incidence of a not predicted behavior of the self-regulated learning theory was identified and to classify it was created a pattern called low participation.

3
  • AGNALDO SOUZA CRUZ
  • Osseus - Method based on Artificial intelligence and Electromagnetic Waves for the Auxiliary Diagnosis of Osteometabolic Diseases.

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • HERTZ WILTON DE CASTRO LINS
  • KARILANY DANTAS COUTINHO
  • MARTA ROSECLER BEZ
  • RAIMUNDO VIEGAS JUNIOR
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Apr 9, 2018


  • Show Abstract
  • Known as a silent disease, osteoporosis is a systemic metabolic bone disorder characterized by low bone mineral density (BMD), compromising the microarchitecture and bone resistance, exposing the individual to fractures risk and consequent impairment of life quality, affecting their mobility, independence; after the fracture it can cause chronic pain, deformity, depression or death due to medical complications.

    In Brazil, it is estimated that in a 20-year period there was a 50% increase in the number of people with a higher probability of developing osteoporosis,the projections for 2050 estimate that the number of hip fractures for men and women aged around 50 to 64 years old will increase by 400%, moreover, the increase for the age groups over 65 years will have 700% increase. In a three-year period,  3,252,756 procedures were performed related to the osteoporosis treatment in the Brazilian elderly population, which generated an expense of R$ 288,986,336.15. The diagnosis and the early treatment of this disease are fundamental for the execution of preventive measures, avoiding the occurrence of fractures.

    This is a great challenge for a country of continental  proportions such as Brazil (5,564 municipalities), with a considerable socioeconomic diversity and amplitude in both population and area. Diagnostic equipment for osteoporosis has a high cost, making them unfeasible in all municipalities of the federation.

    This thesis presents a tool for the initial diagnosis of osteometabolic diseases. This instrument is a combination of the techniques and concepts from several areas such  as: biomedical engineering, software engineering, electrical engineering, computer engineering. Due to these characteristics, the initial osteongporosis examinations are able to be performed in any of the 5,564 municipalities of Brazil with annual periodicity according to the parameters established by the Decree number 1.10/GM, from the Ministry of Health. 

4
  • FRANCISCO DAS CHAGAS BARBOSA DE SENA
  • Optimization of DGS and PBG Structures in Rectangular Microfine Antennas Using Genetic Algorithm

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO DIONISIO DE ANDRADE
  • JOSE PATROCINIO DA SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ÁDLLER DE OLIVEIRA GUIMARÃES
  • Data: Apr 13, 2018


  • Show Abstract
  • Microstrip antennas have attracted the attention of researchers worldwide because of their interesting features for various applications. However, disadvantages such as low gain, narrow bandwidth and low radiation efficiency can limit their use in a given system. Besides, this type of antenna can excite higher order modes in addition to the fundamental. This feature is particularly important for systems with multiple operating frequencies, in other cases, it is necessary to use filters to eliminate the unwanted modes. Alternatively, arrangement of defects can be added to the ground plane or substrate antenna to achieve the same aim, such structures are named Defected Ground Structure (DGS) and Photonic Band Gap (PBG), respectively. However, the development of really efficient projects involving these types of structures presents great dependence on the correct specification of the physical parameters of the used arrangements. In this context, aiming at eliminating and/or attenuating the higher order modes, without significantly affecting the performance of the antenna to the fundamental mode, the present work studied the application of a Genetic Algorithm (GA) in the development of new models with DGS and PBG. The proposed models are composed of circular holes, filled with air, in the hexagonal and rectangular patterns for the periodic configuration and with micro structured pattern for the quase periodic configuration. The proposed GA was responsible for specifying the following parameters of the analyzed arrangements: diameters of the holes, distance among them and the location of the arrangement along the length of the antenna. Based on the obtained results, it was verified that the proposed GA was able to optimize the analyzed structures in order to preserve the fundamental mode of the analyzed antennas, whereas the higher order modes were eliminated and/or considerably attenuated. It was also verified that for the same type of arrangement, the antennas with DGS presented better performance regarding to those with PBG, considering the reflection coefficient to the fundamental mode. In addition, the optimized structures did not show significant variations in the gain or radiation pattern and they exhibited important characteristics to miniaturization projects. The obtained results are particularly important, assuming that optimized structures can be used to eliminate higher order modes in application with passive or active microstrip antennas which also operate as resonators.

     

5
  • MÁRCIO EMANUEL UGULINO DE ARAÚJO JÚNIOR
  • MPC Predictive Control of Electropneumatic Position Valves with Grip

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ADEMAR GONÇALVES DA COSTA JÚNIOR
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE BEZERRA DE MENEZES FILHO
  • Data: Apr 13, 2018


  • Show Abstract
  • This work presents the implementation of a system that deals with static friction (stiction)
    in electropneumatic control valves, one of the most common nonlinearities that causes
    problems such as limit cycles and consequently wear of the valve and its moving
    parts, as well as losses in production and maintenance costs. This system is composed
    of a non-linear predictive controller with adjustable constraints and an online database
    for estimation of the stiction parameters. The predictive controller uses constraints on
    the valve speed during its excursion, as well as constraints on the control signal to bring
    the valve to the desired position and slip it when necessary. The strategy adopted also
    showed robustness, being able to cope with changes in the spring and stiction parameters,
    which caused mismatch between the valve model and the present controller model, the
    that should cause loss of performance or even instability.

6
  • GLAUCO GEORGE CIPRIANO MANIÇOBA
  • Analysis and Modeling of the Electromagnetic Speed Regulator for Wind Energy Conversion Systems. 

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALBERTO SOTO LOCK
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • PAULO VITOR SILVA
  • Data: Apr 24, 2018


  • Show Abstract
  • Nowadays, the growing increase in energy demand worldwide intensifies the search for the use of clean and renewable energy sources. Within this scenario, wind energy has been highlighted with one of the most promising.

    The objective of this work is to analyze the characteristics of the proposed speed reduction system between a wind turbine and a synchronous generator. In this type of system eliminates the need for mechanical speed reduction system, usually sophisticated, high cost, frequent maintenance and not very high reliability.

    The FER also eliminates  the  use  of  electronic  converters  to  establish  the  coupling between the wind turbine and the grid, which is why it also provides the possibility of obtaining alternating current generation.

7
  • IRIA CALINE SARAIVA COSME
  • Recursive inversion of block matrices with limited memory usage

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • ADRIAO DUARTE DORIA NETO
  • DANIEL ALOISE
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • AURELIO RIBEIRO LEITE DE OLIVEIRA
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • Data: May 4, 2018


  • Show Abstract
  • The inversion of extremely high order matrices has been a challenging task because of the limited processing and memory capacity of conventional computers. In a scenario in which the data does not fit in memory, it is worth to consider exchanging less memory usage for more processing time in order to enable the computation of the inverse which otherwise would be prohibitive.

    Therefore this work introduces a novel algorithm to compute the inverse of block partitioned matrices with a reduced memory footprint. The algorithm works recursively to invert one block of a k×k block matrix M, with Mk×k , based on the successive splitting of M. This algorithm, called BRI (Block Recursive Inverse), computes one block of the inverse at a time to limit memory usage during the entire processing.
    Considering that the low memory consumption, provided by the BRI, is counterbalanced by longer processing time, this work also discusses a parallel implementation in OpenMP of the algorithm to reduce the execution time and to extend its applicability. Besides, an improvement in the sequential algorithm is analyzed.
    As a practical application, the proposed algorithm was applied in the cross-validation process for Least Squares Support Vector Machines (LS-SVM), introduced by An et al. (2007). This computational procedure uses the inverse matrix calculation to find the expected labels of the test samples in the cross-validation.
    Experimental results with BRI show that, despite increasing computational complexity, matrices that otherwise would exceed the memory-usage limit can be inverted using this technique.

8
  • NIVALDO FERREIRA DA SILVA JÚNIOR
  • Multivariable Nonlinear Iterative Prediction Control Under Restrictions with Reduced Temporary Complexity

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • ROBERTO KAWAKAMI HARROP GALVAO
  • VICENTE DELGADO MOREIRA
  • Data: May 25, 2018


  • Show Abstract
  • This thesis deals with the numerical resolution of optimal control problems using an iterative Model Predictive Control (MPC) method for non-linear multivariable systems that satisfies the constraints. This iterative method was recently presented in the literature and avoids the need to solve a nonconvex optimization problem using a time-variant linearization of the nonlinear model of the system, which is iteratively adjusted by solving at each sampling time an iterative optimization problem using the quadratic programming.The main advantage is the faster resolution of the optimal control problem using quadratic programming rather than non-linear programming, while maintaining an appropriate description of the nonlinear dynamics of the process being controlled.The approach presented is an evolution of the original iterative algorithm and includes a modification that improves the optimality of the predictions, based on the convergence analysis of the method, and a tightening strategy of the state definition domain for constraint observance, which is based on reachable sets obtained using the interval arithmetic.Firstly, MPC as an optimal control technique is presented. Next, we analyze some MPC approaches available in the literature that deal with the reduction of the time complexity of the method, and then the proposed approach is introduced, being systematically discussed the convergence of the method and its uncertainty, a new and concise mathematical description of the algorithm, the technique for observing the constraints, as well as the aspects related to its implementation. In sequence, applications of the proposed algorithm are presented to demonstrate the feasibility of the approach used and to emphasize the form of its application.

9
  • IRADILSON FERREIRA DA COSTA
  • Use of Split Ring Resonators and it Complementary for Performance Improvement in Low-Pass Microstrip Filters 

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • JOSE PATROCINIO DA SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • MAURICIO WEBER BENJÓ DA SILVA
  • Data: Jun 20, 2018


  • Show Abstract
  • This work presents high performance microstrip lowpass filters. Three different filter configurations are modified by the judicious insertion of split-ring resonators (SRR) and complementary split-ring resonators (CSRR). These resonators are used to improve the roll-off and to remodel the rejection band of the filters, achieved by removing undesired transmission spurious bands. The improvements in these circuits are verified using performance parameters such as selectivity, transition bandwidth, rejection bandwidth and insertion loss, obtained by simulation and measurement of the designed microstrip lowpass filter. Values of selectivity ranging from 60 to 86 dB/GHz are achieved, with rejection bandwidths from 2 to 10 GHz. The insertion of the resonators does not result in major modifications in the passband and the group delay of the analyzed filters. The filters used have values of order from 3 to 9. Besides, a low cost dielectric substrate has been implemented. Though lossy, this substrate meets the intended requirements.

10
  • FRANCISCO CARLOS GURGEL DA SILVA SEGUNDO
  • Computational Intelligence Techniques Application for Multiband and/or Broadband Frequency Selective Surface for Commercial Applications

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ALLAN DE MEDEIROS MARTINS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • GUTEMBERGUE SOARES DA SILVA
  • Data: Jun 20, 2018


  • Show Abstract
  • Frequency Selective Surface (FSS) have an important role in telecommunications due to technological advances in order to meet the requirement of users every day seeking technologies that achieve ever-higher transmission rates and are multifunctional. One of the alternatives found were the appearances of UWB technology and multiband technology, which ensures that telecommunications networks operating in several frequency bands reducing operating and system deployment costs. Given these requirements, we seek for FSS that have this type of behavior. To find FSS with such characteristics, one can make use of computational intelligence techniques in order to achieve optimal structures. Among the techniques, it has artificial neural networks, which will be object of study in this work in order to get a FSS with multiband and/or wideband response applied commercial. The FSS project based on a geometries square loop, double square loop, Jerusalem cross and a geometry unpublished in literature developed in this work.

11
  • FRANCISCO ELVIS CARVALHO SOUZA
  • Optimization of the Drive Structure for the Radial Position Control of a Three-Phase Bearingless Divided Winding Induction Motor 

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE ALVARO DE PAIVA
  • JOSE ANDRES SANTISTEBAN LARREA
  • JOSSANA MARIA DE SOUZA FERREIRA
  • Data: Jun 21, 2018


  • Show Abstract
  • In bearingless motors or self-bearing motors, the motor and bearing functions are combined, that is to say, in the stator of the machine circulate currents that produce on the rotor besides the torque, also radial forces that support the rotor in the center of the stator. Thus, these machines do not suffer from the common wear of mechanical bearings, do not require lubrication, operate without noise and are suitable for applications with high rotational speed. In spite of all the advantages of the self-bearing motors, their operation requires a drive structure equipped with many components such as: electronic power switches, sensors, electronic interfaces and digital signal processors that make their application more expensive. The purpose of this work is to optimize (decrease) the number of components necessary for the operation of the self-bearing motors, both for the control of the radial position of the rotor and for its drive, to achieve this the following strategy was devised: instead of controlling the currents of the three phases, which requires the control of six currents, the currents of only two are controlled, the current of the third phase being produced by the sum of these. With this, the control structure would only use 4 electronic switches (IGBT), 4 drives (electronic interface for IGBTs), 4 current sensors and 4 current controllers, instead of 6 of these devices and 6 required current controllers for control with the three phases. This strategy was implemented in a prototype of 250-watt induction self-bearing motors that works in the upright position. The experimental tests showed results similar to results obtained with three-phase control techniques. 

12
  • KAYO GONCALVES E SILVA
  • Perpetual Orbit and other Robust Global Optimization Techniques for the Coupled Simulated Annealing and Nelder-Mead Algorithms

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • CALEBE DE PAULA BIANCHINI
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • LIACIR DOS SANTOS LUCENA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • SAMUEL XAVIER DE SOUZA
  • Data: Jun 28, 2018


  • Show Abstract
  • Metaheuristics are algorithms whose strategy is to reduce the computational load to the detriment of the non-optimal quality of solutions. They are widely used to approximate solutions of computationally intractable optimization problems. Although typically simple to implement, some metaheuristics suffer because of lack of robustness for tuning some initialization parameters, which requires a very expensive tuning process due to its empirical nature. This work presents the development of three new metaheuristics based on free-parameter, less is more (LIMA) and parallel approaches, aiming to make some metaheuristics robust. As results, the algorithms Simplified Nelder-Mead algorithm (SNM), Syncrhonous (SCSA) and Asynchronous Coupled Simulated Annealing (ACSA), and Perpetual Orbit Coupled Simulated Annealing (PO-CSA) were proposed. The SNM is the result of the LIMA approach and the Nelder-Mead (NM) method. While its implementation has far fewer points than the original algorithm, its ability to perform several simple steps makes it able to find better results than the original NM even for non-convex functions. The SCSA and the ACSA are parallel implementations of Simulated Annealing Coupled (CSA) that allow the user to efficiently choose one or another version based on the size of the problem and the number of optimizer cores. The Perpetual Orbit (PO) technique was developed to control the generation temperature of the CSA to make it parameter free. The algorithm PO-CSA takes advantage of the PO technique combined to the CSA’s automatic quasi-optimal scheduling of the acceptance temperature to make optimization of the CSA more robust with respect to the initialization parameters. While the PO-CSA performed better than the reference algorithms for the majority of the objective functions, both in quality of solution and execution time, its control of the generation temperature also proved to be more effective than the original CSA with an exhaustively tuned initialization parameters.

13
  • AMANDA GONDIM DE OLIVEIRA
  • Contributions to the Study of Dynamics in Information Theory: Applications in Dynamic Clustering

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • ALUISIO IGOR REGO FONTES
  • DANIEL SABINO AMORIM DE ARAUJO
  • GUILHERME DE ALENCAR BARRETO
  • Data: Aug 3, 2018


  • Show Abstract
  • Information Theory is a branch of mathematics, more specifically probability theory, that studies information quantification. Recently, several researches have been successful with the use of Information Theoretic Learning (ITL) as a new technique of unsupervised learning. In these works, information measures are used as criterion of optimality in learning. In this work, we will analyze a still unexplored aspect of these information measures, their dynamic behavior. The main objective of this work is to investigate the use of measures of information theory in the context of dynamic processes. For this, the same was done in 3 (three)  distinct phases. In the first phase we investigated the presence of dynamics in the information in the processes. As a source of dynamic information, videos with different characteristics were used. The second phase presents a new representation for dynamical processes by state space called Information State Representation. In this representation, the states of the system are described as a function of the information measures of the system. To validate this new form of representation, some experiments were carried out with videos aiming at evaluating its quality when submitted to different dynamic aspects. In the third phase, we investigated the use of measures based on information theory within the area of dynamic clustering. The objective in this phase was to compare the performance of the use of measures of information theory with traditional measurements in the operations of merge and split between clusters. The results obtained in all the phases were quite satisfactory meeting the objectives proposed in the work.

14
  • GUSTAVO FONTOURA DE SOUZA
  • A Statistical Methodology for Analysis of the National Program for Improving Access and Quality of Primary Care (PMAQ-AB)

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRÉ LUIS BONIFÁCIO DE CARVALHO
  • ANGELO GIUSEPPE RONCALLI DA COSTA OLIVEIRA
  • KARILANY DANTAS COUTINHO
  • MARIA CRISTINA SOARES GUIMARAES
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Aug 17, 2018


  • Show Abstract
  • The National Program for the Improvement of Access and Quality of Basic Care (PMAQ-AB) is a program of the Ministry of Health aimed at improving access and quality in Primary Health Care. The third phase of the Program consists of external evaluation, in which a set of actions will be carried out that will verify the conditions of access and quality of the Basic Attention of the teams participating in the program. This phase presents an extensive questionnaire that deals with several dimensions of Primary Care. This work proposes that, using statistical methodologies, to analyze the evaluation instrument indicating weaknesses and proposing improvements to it. First approach concerns excess of missing data that is handled through an indicator constructed to provide a cut-off point of missing data maximizing the amount of data to be maintained. Second approach seeks validate the set of items (questions) that present a single construct, using Item Response Theory (TRI) was used to identify the items that present low discrimination in order to, if necessary, be reformulated or removed from the questionnaire.

15
  • FILIPE EMANUEL VIEIRA TAVEIROS
  • A NOVEL CONTROL STRUCTURE TO ENHANCE THE DFIG-BASED WIND ENERGY CONVERSION SYSTEM INTEGRATION TO THE GRID

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • ANDRE LAURINDO MAITELLI
  • JOSSANA MARIA DE SOUZA FERREIRA
  • LUCIANO SALES BARROS
  • FRANCISCO KLEBER DE ARAÚJO LIMA
  • JOHAN DRIESEN
  • Data: Aug 24, 2018


  • Show Abstract
  • The doubly fed induction generator (DFIG)-based wind energy conversion system (WECS) currently leads the wind energy market due to its advantages in comparison to other topologies. In this system, the generator stator is directly connected to the grid, while the rotor is connected to the grid by means of a back-to-back power converter scheme. The appropriate control of the converters allows the wind turbines based on the DFIG to operate in variable speed mode, whose benefits include maximum extraction of the power available in the wind, reactive power injection and mechanical stress reduction. Meanwhile, the increasing number of wind energy conversion systems has led the grid operators to develop specific regulations regarding the connection of these systems to the grid. Under these regulations, the fault ride-through and low voltage tolerance are amongst the most important and relevant aspects, as well as to provide reactive power to the grid in order to restore the voltage level during a fault. Therefore, such systems must maintain a high level of controllability during grid disturbances. This thesis investigates the impact of control and drive strategies on the performance of the DFIG-based wind energy conversion system, under the perspectives of maximum power extraction and fault ride-through, according to the grid regulations of Brazil, Canada, the United States and Germany. It is proposed a new heightened state-feedback control structure with predictive behavior and real time estimation of the parameters to be applied to the generator control, which considers in an integrated manner the dynamics of the machine currents in conjunction with the general modelling of the electromagnetic disturbance present during symmetric and asymmetric voltage sags, as well as the tracking errors. The proposed structure was designed to effectively suppress the oscillation dynamics present in the back electromotive force that occurs in the case of a grid voltage disturbance in order to mitigate oscillations and surges in the electromagnetic torque and the machine currents, exempting the need to use current reference modification strategies or the activation of physical protection, thus allowing the DFIG to provide reactive power during symmetrical and asymmetrical disturbances in the grid featuring limited torque oscillations. Results obtained by means of real-time digital simulations and experimental tests under ideal and non-ideal conditions demonstrate the superiority of the proposed structure in comparison to conventional and previous techniques.

16
  • WELLINGTON BARBOSA DO NASCIMENTO JÚNIOR
  • Human-Robot interaction and User Experience in the Programming and Execution of Tasks using a Gestures Programming Language

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • FRANCISCO DE ASSIS PEREIRA VASCONCELOS DE ARRUDA
  • ORIVALDO VIEIRA DE SANTANA JUNIOR
  • PAULO HENRIQUE LOPES SILVA
  • RAFAEL BESERRA GOMES
  • Data: Aug 28, 2018


  • Show Abstract
  • A more friendly robot interaction using natural languages has been a challenge and subject of several studies. This work makes a survey of the tasks of a mobile robot - Robot-Cart, and performs a procedure to develop an vocabulary of gestures with a particular focus on the elaboration of a programming language through gestures for the robot. The objective is to fill some gaps in the related works. By means of the comparative analysis of these works we verified the lack of processes for the development of gestures and the absence of methodology for validation of the described language. Another point observed is that the use of the natural language for the communication between the human and the robot has the purpose of conducting them in established trajectories or to perform predefined tasks. In this way this research presents a programming language through gestures, which allows users with no experience or almost no experience in programming or robotics to program a robot-car in a simplified and satisfactory way. To achieve the goal a methodology for the development of the gesture vocabulary is described and then performed with the participation of volunteers. To validate the efficiency of the programming language two experiments were performed with real users. Interaction Test and User Experience techniques were used. The results are satisfactory and show that the programming language developed meets the requirements of learning, ease of use, efficiency, memorization, low error rate and user satisfaction and can be used as an alternative to teaching and learning programming and robotics.

17
  • DIEGO ANTONIO DE MOURA FONSECA
  • Implementation of data transmission system through the power line of the wells with the eletrical submersible pump lifting method.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • FILIPE DE OLIVEIRA QUINTAES
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • Data: Aug 31, 2018


  • Show Abstract
  • Power Line Communication (PLC) is a widely used data transfer technology in the industrial world. In the petroleum area this technology is applied in the artificial elevation method by Submersible Centrifugal Pump (BCS) in which information of intake pressure and pump suction and temperature of the engine casing, temperature of the fluid are sent to the surface through the same three-phase cable feed. However, this application occurs in a heuristic way and without a detailed study of the communication channel, which can vary from 700 meters to 2000 m in terrestrial wells, which imposes certain limitations on the potential of the technology. One of the main consequences is the low rate of data communication, which is currently in the range of 2 Hz.

    In view of this scenario it is proposed a more in-depth analysis of the physical environment, raising its characteristics, influence of synchronous and asynchronous noise, temperature, besides considering its behavior over time. With the possession of this study it will be possible to model and, therefore, to develop ways to make possible the increase of the transmission rate through an adequate protocol, considering coding, modulation and nature of the transmitted signal. The automatic adjustment of the mode and speed of communication due to the constant degradation of the channel can be implemented in a way to maximize its time of use.

18
  • BRUNO AUGUSTO FERREIRA VITORINO
  • Sigma-Delta Thermal Converter with automatic adjustment of operating range for incident radiation measurement

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • DIOMADSON RODRIGUES BELFORT
  • VALENTIN OBAC RODA
  • JOSE CAMARGO DA COSTA
  • RAIMUNDO CARLOS SILVÉRIO FREIRE
  • Data: Sep 6, 2018


  • Show Abstract
  • The incident thermal radiation measurement, including infrared and solar radiation, has several applications and increasing demand. In the infrared (IR) radiation measurement, resistive microbolometers are the most used sensors, being applied in complex thermal imaging and detection systems. Some researches aims to increase the sensitivity of IR detection systems, as well as to integrate new functions such as analog-to-digital conversion, together with sensors. The measurement of solar radiation has as main applications the meteorology, photovoltaic plants and studies for agriculture, being the pyranometer the most used instrument. Thermoresistive sensors have been used to measure temperature, fluid speed and direction and radiation. In several architectures the sensor operates in closed loop, increasing the sensitivity, decreasing the response time and linearizing the systems response. The most used closed-loop architectures are the Wheatstone feedback bridge, control systems, capacitive coupling feedback and Thermal Sigma-Delta Modulator (TΣ∆M). TΣ∆M is a closed-loop measurement approach where the sensing element performs part of the Σ∆ modulation in the thermal domain. A new architecture is proposed in this work for measuring thermal incident radiation using thermoresistive sensors, were the modulator input range is automatically adjusted to fit the complete thermal radiation. The proposed architecture is compared with a similar one, which uses the same transducer interface circuit but without range adjustment, and is validated experimentally with a reference pyranometer. The proposed architecture has the main advantage of presenting a signal-to-noise ratio, and sensitivity, that is independent of the ambient temperature range definition. Experimental results for ambient temperature range of 45 ◦C shows a gain of 13 dB over the similar one.


19
  • ANDRÉ SOFFIATTI
  • Analysis of Dielectric Permittivity of Materials using Microstrip Antenna with Metamaterial Substrate

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • JOEMIA LEILANE GOMES DE MEDEIROS MARTINS
  • MARCOS TAVARES DE MELO
  • Data: Sep 28, 2018


  • Show Abstract
  • This work has as main objective the development of an electromagnetic sensor using metamaterial substrate in order to characterize materials through the determination of the dielectric permissiveness in terms od electromagnetic transmission of radio waves. Through simulations and measurements, it is possible to analyze the quality of solid, liquid and gaseous substances by means of relative permittivity analysis, and thus to obtain a standard to control using the variation of the intrinsic and extrinsic characteristics of these substances. The proposed technique is a candidate for applications in material control in industries.

20
  • AMANDA DANIELLE OLIVEIRA DA SILVA DANTAS
  • Design of Controllers with Reduced Complexity for Constrained Linear Systems Using Data Cluster Analysis

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • EUGENIO DE BONA CASTELAN NETO
  • JOSÉ MÁRIO ARAÚJO
  • Data: Oct 1, 2018


  • Show Abstract
  • Controller design for discrete-time linear systems subject to constraints can be carried out based on the concept of invariant sets, together with the solution of multiparametric programming problems. Such a solution is represented by a set of polyhedral regios associated to a Piecewise Affine (PWA) control law. However, for high-order systems, the multiparametric linear programming technique may result in controllers of high complexity, which require a hardware with great storage capacity in the memory and high processing power due to the a high number of polyhedral regions defining the PWA law. In this work we propose a number of numerical methods which aim to reduce the complexity of such controllers. To this end, the concept of invariant sets and the K q-flat data cluster analysis algorithm are applied. First, we show that the K q-flat algorithm can be used to establish a smaller number of polyhedral regions associated to a PWA state feedback control law. Then, this approach is extended to the design of static output feedback controllers for constrained systems and of state observers with error limitation. In addition, optimization problems are proposed to compute a suboptimal PWA law capable of further reducing the number of polyhedral regions. The results we present show that the proposed approaches are able to compute PWA laws with a smaller number of polyhedral regions when compared with the multiparametric solution, strongly reducing the computational cost associated to their implementation.

21
  • GUSTAVO BEZERRA PAZ LEITAO
  • Online Classification of Abnormal Situations in Operation of Industrial Processes Based on Alarms and Process Variables

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • DIEGO RODRIGO CABRAL SILVA
  • MÁRIO CESAR MELLO MASSA DE CAMPOS
  • RODRIGO SIQUEIRA MARTINS
  • Data: Nov 9, 2018


  • Show Abstract
  • Industrial processes are subject to failures in their thousands of components at any time and can lead to shutdowns, loss of product quality, equipment damage or even accidents. In this sense, the alarm system is necessary to aid in the identification of process abnormalities. However, during a process failure it is common for the operator to be subjected to hundreds of alarms causing overload beyond the human processing capacity. This phenomenon is known as alarm flood and to treat them properly is a challenge for the modern alarms systems. Thus, the present work aims at the development of an on-line alarm processing methodology capable of assisting the operator in the identification and classification of abnormal situations of the process, especially in moments of alarm overload. To validate the proposal, a case study was carried out on a process simulator widely used and accepted by the scientific community called Tennessee Eastman Process.

22
  • ANTONIO WALLACE ANTUNES SOARES
  • Analysis and Design of a 4th-Order Incremental Sigma-Delta A/D Converter

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • ANTONIO PETRAGLIA
  • CLEONILSON PROTASIO DE SOUZA
  • DIOMADSON RODRIGUES BELFORT
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Nov 23, 2018


  • Show Abstract
  • The Multielectrode Arrays (MEA) manufactured on CMOS standard technology integrated circuits have allowed the study of several types of cell cultures, allowing the stimulation and recording of electrical activities of the cells in vitro. As the CMOS technology advances, the biomedical signal processing is suitably done in digital domain. Therefore, basic blocks such as Analog to Digital Converters (ADC) are essential to realize the interface in the mixed signal systems. In this way, this work proposes the design of an ADC to be applied in the multichannel biomedical signal acquisition systems, following the top-down approach for the Integrated Circuit design (IC). The architecture of the ADC consists of an Incremental Sigma Delta  Converter (IΣΔ), which combines the high-precision characteristic of the traditional $\Sigma\Delta$ modulators with the advantage of the sample-by-sample conversion of the Nyquist converters, making it suitable for multichannel time-multiplexed applications. The modulator and digital filter which compose the IΣΔ ADC consist of the  single-loop Cascaded-Integrator FeedForward (CIFF) and Cascade-of-Integrator (CoI) topologies respectively, both fourth-order. The modulator was implemented in Discrete Time (DT), using the Switched Capacitor technique (SC). The circuits were designed using TSMC 0.18 um CMOS technology and the results were obtained from post-layout simulations.

23
  • XIANKLEBER CAVALCANTE BENJAMIM
  • Use of Predictive Technique in a control mesh in Wireless Sensors

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • ELMER ROLANDO LLANOS VILLARREAL
  • JUAN MOISES MAURICIO VILLANUEVA
  • RODRIGO SOARES SEMENTE
  • Data: Dec 14, 2018


  • Show Abstract
  • In this work, we propose a strategy of control of a plant using a wireless sensor feedback. To solve the inherent problem of the wireless sensors of data loss and signal fading, Model Based Predictive Control (MPC) is used. This technique, based on the model of the plant, can estimate the states of the same during the loss of the package increasing the robustness of the system and minimizing the impact on the control mesh. A sensorless level control mesh was developed for a second order plant, emulating a coupled tank system. Simulations and experimental tests were performed to verify the performance of the wireless control system for different packet loss rates. In the implementation, the following components were used: 2.4GHz Transceiver (nFR2401) and ATMega 328p microcontrollers to close the control mesh, and to implement the predictive strategy was used in a computer in the MATLAB environment. The simulated and experimental results are presented showing a good control response for packet loss of up to 30%.

24
  • LUÍS FELIPHE SILVA COSTA
  • N-Learning: an approach to autonomous learning and teching in multi-robot systems

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • ROSIERY DA SILVA MAIA
  • TIAGO PEREIRA DO NASCIMENTO
  • Data: Dec 17, 2018


  • Show Abstract
  • We propose the N-Learning, an architecture that provides teaching and learning skills in autonomous Multi-Robot Systems. Our approach allows the robots to learn new behaviors in time execution. The N-Learning is Behavior-Based Robotics and based on Learning by Social Interactions. The behaviors in a robot are represented by a graph. Complex behaviors can be decompose into simpler behaviors that run simultaneously in the robot. An advantage of N-Learning is that is possible to change the robot domain without reprogram the robots. A robot that have behaviors for a specific domain can change it and learn with the other robots. This advantage is useful when exists a large number of robots. We developed an implementation of N-Learning based on Python language and Robotics Operating System. Experiments were performed in Stage simulator and with real robots in order to validate our approach.

25
  • JAILTON CARLOS DE PAIVA
  • SMART: Monitoring and Evaluation System of the National Telehealth Program Brazil Networks
  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • KARILANY DANTAS COUTINHO
  • ADEMAR ARTHUR CHIORO DOS REIS
  • ANTONIO HIGOR FREIRE DE MORAIS
  • THAISA GOIS FARIAS DE MOURA SANTOS LIMA
  • Data: Dec 20, 2018


  • Show Abstract
  •  The Telehealth Program was established by the Ministry of Health (MH) in 2007 with nine technical and scientific centers administered by public higher education institutions and, since its inception, no standards, processes, applications or quality indicators have been defined. The lack of these definitions, allied to the decentralization of the centers, made each one of them to develop their own Information Systems (IS), with different types of language and architectures, without any regulation and integration of information with the MH, hindering thus the evaluation of the program against the offered services . In this context, this paper describes a solution proposed to integrate the data produced by the various heterogeneous systems developed and maintained by the telehealth centers in Brazil in a central data store so that the MH can monitor and evaluate the results of the actions of Telehealth. This solution consists of specifying a National Interoperability Model and the specification, implementation and validation of an architecture, entitled SMART, based on Business Intelligence (BI) and Service Oriented Architecture (SOA) paradigms. SMART architecture consists of four main components: web tool for information manipulation with a interactive interface for data exploration; a component for receiving the data produced by the IS of the centers; a component responsible for saving the received data in decision support data and; a component that collects data from external sources to compose the data warehouse (DW). For the architecture validation, two experiments were performed. The first one executes performance tests under high and extreme workload and the second experiment evaluates if the proposed optimization strategies contribute to the performance and efficiency of the architecture. The results of the experiments were summarized to attest to the effectiveness of SMART.  The analysis of the results obtained on real data showed that the performance of SMART remained stable over the considered workloads and the high quality was proven since no errors were recorded during the experiments. 

26
  • FRANCISCO JADILSON DOS SANTOS SILVA
  • Estimation of oxygen uptake rate in an activated sludge reactor using Kalman filter and PWM control of the dissolved oxygen concentration.

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • ANDRES ORTIZ SALAZAR
  • CARLOS EDUARDO TRABUCO DOREA
  • SAMAHERNI MORAIS DIAS
  • ADRIANUS CORNELIUS VAN HAANDEL
  • CÍCERO DA ROCHA SOUTO
  • Data: Dec 21, 2018


  • Show Abstract
  • The availability of real-time information about the biological activity is a valuable
    matter in wastewater treatment employing activated sludge processes, and this is
    represented by the oxygen uptake rate (OUR). In these processes, the OUR has been
    used as a fast indicator of changes in waste influent organic load or inflow of toxic
    organic compounds that could adversely affect the process. Furthermore, it can be used
    for monitoring of the quality and efficiency of the process and for system control. The
    OUR is usually measured by using respirometers, devices based on some technique to
    measure the rate at which the activated sludge consumes the dissolved oxygen (DO)
    available in the liquid. The objective of this work is to proposed a method for OUR
    estimation by using the Kalman filter and PWM control of the dissolved oxygen
    concentration in an activated sludge reactor. The proposed method presents a shorter
    response time and a lower measurement uncertainty when compared to the standard
    online procedure and a similar method, respectively. Numerical simulations and
    experiments conducted in a laboratory scale activated sludge reactor are used to
    evaluate the proposed method and the results confirm its validity.

27
  • EDUARDO AMORIM MARTINS DE SOUZA
  • Compact and miniaturized antennas for cubesat standard wireless and nanosatellite systems

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • HERTZ WILTON DE CASTRO LINS
  • LAERCIO MARTINS DE MENDONCA
  • MARCOS TAVARES DE MELO
  • Data: Dec 28, 2018


  • Show Abstract
  • The Information Age has brought to the modern world an ever-increasing demand for more reliable wireless communication systems with greater information transmission capabilities. Allied to this, it has been observed that the society has presented an increasing necessity for radiofrequency transmission and reception devices, apparatuses, or equipment with smaller sizes. In addition, new satellite systems technologies have been developed, such as nanosatellites, with extremely small dimensions, leading to a constant need for size optimization and manufacturing costs reduction. Planar microstrip antennas have been widely used in wireless mobile communications systems in the microwave and millimeter wave ranges since the mid-1970s. To support the miniaturization of transmitter and receiver devices, it is necessary to develop antennas of increasingly smaller dimensions which can be realized through various techniques. This doctoral thesis presents the use of a new technique for the design of compact microstrip planar antennas, meeting the society's current demands and wishes. Specifically, the proposed technique combines the insertion of vias and Koch fractal contours in microstrip antenna patches into the design and synthesis of planar microstrip antennas that can be used in wireless communication systems and, particularly, in the Brazilian space program, in the development of nanosatellite projects carried out by the National Institute of Space Research - INPE / MCTI.

2017
Dissertations
1
  • MÔNICA MARIA LEAL
  • Wavelet-Based Overcurrent Directional Protection

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FELIPE VIGOLVINO LOPES
  • FLAVIO BEZERRA COSTA
  • JOSE JOSEMAR DE OLIVEIRA JUNIOR
  • MARCELO AUGUSTO COSTA FERNANDES
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Jan 23, 2017


  • Show Abstract
  • Traditionally, the main protection used in low voltage power systems, as distribution systems, is the overcurrent protection due to its simplicity and low cost. However, in these recent years the number of distributed generation connected to the system has been growing, which changes the complexity of the system and require a directional module to complement the diagnostic about the fault, providing information whether is a forward or reverse fault according to reference point. Therefore, in this master work is proposed a directional overcurrent module based on the stationary discrete wavelet transform. This tool could recreate the classic directional overcurrent protection using just current and voltage scaling coefficients (low frequency), which overcome some drawbacks by using discrete Fourier transform and, in some cases, fault detection is faster. The proposed method has been tested by using the IEEE 30 bus with distributed generator and the IEEE 230 kV systems test with distributed parameters.
2
  • PEDRO THIAGO VALERIO DE SOUZA
  • ANALYSIS OF WAVELET CODING IN RADIO SYSTEMS WITH DYNAMIC SPECTRUM ACCESS

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ADRIAO DUARTE DORIA NETO
  • VICENTE ANGELO DE SOUSA JUNIOR
  • EDMAR CANDEIA GURJÃO
  • Data: Jan 27, 2017


  • Show Abstract
  • In mobile communications systems, signals propagate over multipaths over time-varying channels, subject to distortion caused by fading and Doppler shifts. In order to minimize such distortions, coding techniques and transmission diversity may be employed, such as Wavelet Encoding. This technique is based on the orthogonality of the wavelet matrix rows and has the capacity to generate diversity gains, increasing the robustness of the system to time-varying fading, without compromising the spectral efficiency of the system. In this work, the wavelet coding is investigated in scenarios of cognitive radio with dynamic spectrum access. These radio systems have been consolidating as a new paradigm of wireless communications with the advance of digital signal processing techniques. Cognitive radio systems with dynamic spectrum access should be able to perceive unoccupied frequency bands for opportunistic transmissions as well as detect the presence of primary users when they occupy their licensed spectrum. Therefore, a crucial element for the operation of cognitive radio systems encoded by wavelet coding is the ability to sense the signals encoded by this technique. As will be detailed, the possibility of sensing such signals is conditioned to a suitable design of the signal constellation used in the modulation of the coded symbols. In this work, the design of these constellations is done via genetic algorithms, using a multiobjective optimization approach. The developed system is evaluated for its robustness to time-varying plane fading through a bit error probability (BER) versus Eb/N0 analysis, and the possibility of spectral sensing of its signals via cyclostationary analysis and energy detection method. The results indicate the feasibility of the wavelet coding technique in radio scenarios with dynamic spectrum access, with good results of BER performance and sensed signal detection rates.

3
  • DANIEL NOBRE PINHEIRO
  • The Heterogeneous Fuzzy Clustering Problem: Models and Heuristics

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • ERALDO LUIS REZENDE FERNANDES
  • EVERTON SANTI
  • Data: Jan 27, 2017


  • Show Abstract
  • This work proposes formulations for the Fuzzy Heterogeneous Clustering Problem
    and proposes a heuristic method of Variable Neighborhood Search to solve it. The Fuzzy
    Heterogeneous Clustering Problem is a clustering problem that is formulated in two levels. The first identifies groups of individuals whose perceptions about the objects involved are similar. The second level identifies distinct fuzzy partitions of objects for each
    group of individuals. The second level is based on the p-median problem, whose objective is to separate a set of objects into smaller subsets and to define an object as median for
    each subset, such that the sum of dissimilarities between each object and it’s median is minimal. The Fuzzy Heterogeneous Clustering Problem generalizes the p-median problem
    to fuzzy environments, allowing the degrees of membership between each object and each
    cluster to be fractionary. This generalization allows new interpretations about the results,
    such as the identification of simultaneous relationships of objects with different clusters.

4
  • FELIPE FERREIRA DE ARAUJO
  • Simulation and design of reconfigurable planar antennas using metasurfaces

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • GUTEMBERGUE SOARES DA SILVA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Jan 30, 2017


  • Show Abstract
  • All over the world, the evolution of the technological apparatus for telecommunications systems has been increasingly required, as a clear consequence of the exponentially growth in the demand for wireless communication services. Therefore, the integration of multiple wireless standards on a single platform, like a reconfigurable antenna, also known as tunable antenna, is attracting much attention. Metasurfaces structures have been extensively used in recent years to improve the performance of planar antennas for wireless applications, including reconfiguration. A metasurface (also referred to as a metafilm) is the equivalent of a metamateriaI surface. More precisely, one metafilm is a surface with a distribution of small scatterers arranged along a region of space, to achieve desirable electromagnetic behaviors. For many applications, metasurfaces can be used in place of metamaterials because they have the advantage of taking up less physical space than the three-dimensional structures of metamaterials, offering the possibility of reduced losses, which has generated great interest. Therefore, this master thesis presents the simulation, design and implementation of planar antenna structures coupled to metasurfaces structures in order to reconfigure frequency, polarization and multiband antennas for wireless communications applications. The analysis of the antenna structures is performed with the aid of computational tools. Prototypes are fabricated and measured for experimental verification purpose. Simulations and measurements results are in good agreement.

5
  • RAFAELA GOMES GONÇALVES DE CARVALHO
  • SIMULATION AND DESIGN OF MECHANICALLY RECONFIGURABLE FSS FOR MICROWAVE APPLICATIONS

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • Data: Jan 30, 2017


  • Show Abstract
  • Reconfigurability is a very important feature in modern communication systems because it allows the same structure to adapt to different scenarios of the same application, such as radomes, cognitive radio, and adaptive screens that block unwanted wireless transmissions. This characteristic can be achieved by traditional methods, such as the use of active semiconductor devices (PIN diodes, Schottky) or variable capacitors coupled to each basic element of the frequency selective surface (FSS), requiring the use of a separate circuit to feed these components. However, these methods require a high number of active elements, which increases the complexity and cost of manufacturing, opening space for the emergence of simpler and more robust techniques for selectivity, such as mechanical reconfigurability. This work consists of the development of a reconfigurable frequency selective surface (FSS), to operate in the X-band, composed of triangular patch elements printed on a dielectric layer of fiberglass (FR-4). The developed FSS allows the reconfiguration of the resonant frequency from the variation of the angle of the incident wave in the structure, in the TE mode, and can be applied in the cognitive radio technology through a microcontrolled interface. The analysis of the structure of the FSS is done through Ansoft Designer software.

6
  • FELIPE OLIVEIRA SIMÕES GAMA
  • Adaptive Wavelet Coding Design for a Control System on Wireless Channels 

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • MARCELO AUGUSTO COSTA FERNANDES
  • FABIANO FRAGOSO COSTA
  • Data: Jan 30, 2017


  • Show Abstract
  • The wireless sensor networks (WSN) are constituted by nodes interconnected by wireless channels with sensing and control ability. However, due to the use of wireless communication channels, the information exchanged among the sensor nodes are susceptible to the effects of impulsive noise and fading produced by multipath propagation. In order to minimize the fading effects, channel coding and diversity techniques are often used in wireless systems. Among them, the wavelet coding is a good alternative for the WSN by their robustness to the effects of the wireless channel and by its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level, and evaluate the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus Eb/N0, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. So far, results indicate be feasible to implement an adaptive wavelet coding in this communication scenario.

7
  • ANDRÉ QUINTILIANO BEZERRA SILVA
  • Implementation and Use of Algorithms for Conversion and Learning in a Neuro-Symbolic System
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ADRIAO DUARTE DORIA NETO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • GILBERT AZEVEDO DA SILVA
  • Data: Feb 14, 2017


  • Show Abstract
  • One of the main goals of artificial intelligence is the creation of agents with human-like intelligence. This has been researched using various approaches, and among the most prominent  for machine learning are logic-based symbolic systems and artificial neural networks. Until the last decade, both approaches have progressed independently, but progress in both areas has led researchers to investigate ways to integrate both approaches. Several models that provide hybrid or integrated integration of these approaches emerged in the 1990s, and continue to be used to this day. This work has as main objective the implementation of the Neuro-Symbolic conversion algorithm of the KBANN (Knowledge-Based Artificial Neural Networks) hybrid system, which has the ability to map the dependencies of a specific domain of rules (if-then) in a Neural network, and then refine that network using learning techniques. In addition, since this model does not have the ability to refine the network topology in order to obtain new rules for the initial domain, it was necessary to implement another algorithm to the original KBANN model, in order to obtain possible expansions of the original network. KBANN.

8
  • VERIVAN SANTOS LIMA
  • PROTOTYPES FOR THE EVALUATION OF FLOW MEASUREMENT METHODOLOGIES FROM THE THERMAL PROFILE IN WATER INJECTORS

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • CARLA WILZA SOUZA DE PAULA MAITELLI
  • BENNO WALDEMAR ASSMANN
  • Data: Mar 6, 2017


  • Show Abstract
  • This work aims at the development of a small scale instrumented prototype for the evaluation of the equation developed by Ramey Jr. in 1962. It will be calculated the flow, starting as the thermal profile of the fluid in water injectors in production fields Of oil. Firstly, a bibliographic summary will be presented, describing not only Ramey's theory, but all the minimal information necessary to the understanding and development of the prototype. Finally, it will be passed on the prototype in and on the instrumented plant installed in the LAMP (Laboratory Applied to the Oil Mediation) of UFRN, as well as on the results obtained in the tests that were performed.

9
  • BRUNNA SANTANA DE VASCONCELLOS PINHEIRO
  • PROCEDURE PROPOSED FOR FUZZY MULTIVARIABLE CONTROLLERS PROJECT

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • CARLOS EDUARDO TRABUCO DOREA
  • ADEMAR GONÇALVES DA COSTA JÚNIOR
  • Data: Apr 10, 2017


  • Show Abstract
  • Generally, control’s practical problems have many process variables to be controlled simultaneously and, usually they depend on each other. So, there is a necessity of a deep study about multivariable control systems. Then, analyzing the capability and potential of different control strategies is primordial to get the most appropriate control mode according to the system. Once that has been known, this work handles a systematic procedure which explain how to build an effective fuzzy controller for a system which has two or more inputs and two or more outputs. The procedure consists of dividing the controller projects in steps and for each of them, the parameters of the fuzzy controllers are tuned. Those steps get started considering a system which has a single input and a single output. After that, all of the controllers are joined into a single one which get all of the inputs and outputs, and also it has the configuration necessary to know how every single input influences in the outputs. Basically, it is possible to get a better performance and understanding once the behavior of the system is analyzed in which stage of the procedure. In order to prove the efficiency of the procedure, this method is applied to different cases of study, which are practical and simulated cases. The obtained multivariable fuzzy controller is compared with others by using graphical analysis and calculated indexes of performance for validation of the procedure.

10
  • THIAGO CORREIA PEREIRA
  • New heuristics for minimum sum-of-squares clustering

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • DARIO JOSE ALOISE
  • EVERTON SANTI
  • Data: Apr 12, 2017


  • Show Abstract
  • Due to the large volume of data generated by the growth of applications that provide
    new information, both in volume and variety, more efficient techniques are required to
    classify and processes them. A widely used technique is data grouping whose aim is to
    extract characteristics of the entities dividing them into homogeneous and/or well separated subsets. Many different criteria can be used to express the data classification. Among them, a commonly used criteria is the minimun sum-of-squares clustering (MSSC). In this criterion, entities are elements in n-dimensional Euclidean space. The data clustering
    problem by MSSC is NP-hard, then heuristics are extremely useful techniques for this
    type of problem. This work proposes new heuristics, based on the general variable neighborhood search (GVNS). Also proposed in this work is the adaptation of the heuristic reformulation descent (RD) to the MSSC problem, in the form of two variants, unapplied to this problem before in literature. The computational experiments show that the GVNS
    variants proposed in this work present better results, in large instances, than the current state of the art for this problem.

11
  • JOSE KLEITON EWERTON DA COSTA MARTINS
  • Analysis of different control techniques to be used in the modified ANFIS structure

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • CARLOS EDUARDO TRABUCO DOREA
  • MARCONI CAMARA RODRIGUES
  • OSCAR GABRIEL FILHO
  • Data: Jun 23, 2017
    Ata de defesa assinada:


  • Show Abstract
  • This work presents an analysis of different control techniques in the modified ANFIS structure, this method is recent and originated from a change in the ANFIS structure. The method has the capacity to perform identification and control of plants with wide operating range and accentuated non-linearity. The modified ANFIS is divided into two major stages, the first is the identification and the second is the control. In order to perform the identification, it is possible to use any techniques, which may be linear and non-linear techniques. In this work was explored the linear system identification more known in the literature and the least square estimation. For the first, identification, a system of tanks with multisections was chosen as a case study and its identification through the modified ANFIS was performed, showing the qualities of the method. As in the identification stage, the control stage can also use any techniques, but in this work the tuning of PID controllers will be explored, in which the designed controllers will be incorporated into the modified ANFIS structure to obtain a non-linear controller. Then a performance comparison of the modified ANFIS will be performed using the different tuning methods and show a systematic methodology for use the modified ANFIS as global controller. 

12
  • ALAN CASSIO QUEIROZ BEZERRA LEITE
  • Maximum Power Tracking Using the Temperature Based Method with Digital OCC Modulation

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ANDRES ORTIZ SALAZAR
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • Data: Jun 26, 2017


  • Show Abstract
  • Photovoltaic systems have stood out among the different types of renewable sources by directly converting sunlight into electricity, low maintenance, good performance in electricity production and do not produce greenhouse gases. Due to some climatic changes of temperature, radiation and shading on the panel, the production of electricity is compromised and this causes a decrease in the generation efficiency of the photovoltaic panels. Due to this, they need a tracking system that makes the panel operate at the maximum power point. These tracking systems are the so-called Maximum Power Point Tracker – MPPT. The main objective of this work is to build a photovoltaic generation system controlled by a DSP TMS320F28335 and switched converter boost type, so that the system traces the maximum panel power, maximizing your efficiency. In this work a control strategy is implemented based on the panel temperature measurement to provide the reference voltage equivalent to the maximum power point under outside conditions of international testing standards and simulating shading effects of photovoltaic cells and temperature and load variations. According to the temperature read by the sensor LM35, the DSP TMS320F28335 will adjust the reference voltage of the PI controller resulting in a duty-cycle value of the Boost converter. The switch of the boost converter will be done using the control technique One Cycle Control – OCC rather than the widely used Pulse Width Modulation – PWM. The OCC switching technique provides some advantages over PWM as a quick response to the reference change, null error in steady state and rejection of input disturbances. Simulations and experimental results show that this scheme presents some advantages over the conventional Constant Voltage method and other more sophisticated methods like Hill Climbing, besides OCC provide some advantages over PWM.

13
  • MÁRIO SÉRGIO FREITAS FERREIRA CAVALCANTE
  • Interval Fuzzy Type-2 Controllers Optimization

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRE LAURINDO MAITELLI
  • MARCELO AUGUSTO COSTA FERNANDES
  • OSCAR GABRIEL FILHO
  • Data: Jun 27, 2017


  • Show Abstract
  • Differents stategies and control algorithms are already tested and registered by indus- try. Among the existing techniques, fuzzy controllers stand out for their ability to deal with nonlinearities present in real plants. Another fuzzy also allows to best represent ex- pert knowledge, which is mathematically inaccurate. This qualification proposal studied the two types of fuzzy controllers, based on Sugeno Model, the fuzzy type-1 is classified as conventional fuzzy and fuzzy type-2. In this study is used optimization techniques seeking to tune controllers in order to solve one of the biggest problem in fuzzy logic, its tunning. Ant colony, particle swarm and genetic algorithm are used and evaluated to this problem. A servo motor-dc is used to validate fuzzys controllers and pi controller obtained by optimization tecniques. In order to quantify and qualify each controller, three indices were used IEA, ITEA and Goodhart index. The results obtained prove that the type-2 fuzzy controller presented significant gain for the control of this plant, when optimized with the PSO method. From the results, it can also be inferred that the ant algorithm was not adequate for this problem, with the proposed evaluation function. 

14
  • ALLYSON FERNANDES DA COSTA SILVA
  • A Genetic Algorithm with Iterated VND to the Dynamic Facility Location Problem with Modular Capacities
  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • MARCELO AUGUSTO COSTA FERNANDES
  • CAROLINE THENNECY DE MEDEIROS ROCHA
  • LEANDRO CALLEGARI COELHO
  • Data: Jun 30, 2017


  • Show Abstract
  • Location problems aim to determine the best positions where facilities should be installed in order to 
    meet existing demands. Due to its wide applicability, several characteristics have already been appended 
    to the models to better represent real situations. One of them generalizes classical models to the case 
    that location decisions should be taken periodically. Another allows models to deal with capacity sizing
    as a problem variable. The Dynamic Facility Location Problem with Modular Capacities unifies these and 
    other characteristics present in location problems in a single and generalized model. This problem was 
    recently formulated in literature where an exact approach was introduced and applied to instances of a 
    case study in the context of the forestry sector. We present an alternative method to solve the same 
    problem. The method chosen uses a Genetic Algorithm metaheuristic framework and hybridizes it with a 
    Variable Neighborhood Descent routine with three neighborhoods adapted from others applied to location 
    problems. Experiments attested the effectiveness of the hybrid metaheuristic developed in comparison to 
    the use of those methods purely. Compared to the exact approach, the heuristic proved to be competent by 
    finding solutions very close to the global optimum in the majority of the tested instances.
15
  • EVANDRO AILSON DE FREITAS NUNES
  • Analysis of Impacts in the Electrical Network Due to the integration of Photovoltaic Systems Peneration.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ALEXANDRE CUNHA OLIVEIRA
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Jun 30, 2017


  • Show Abstract
  • Currently, incentives for clean energy generation have been increasing considerably due to the limitation of fossil fuels, until then used in abundance. In parallel, distributed generations increase with the reduction of the taxes of the embedded components of the renewable energy sources. However, the power quality (PQ) has been severely affected by the increasing number of these types of energy sources connected to low voltage distribution networks. In this dissertation, the impact on the utility grid will be evaluated under varying levels of a photovoltaic system penetration. A 10 kWp photovoltaic plant, composed of three system topologies connected to a 15 kVA substation common coupling point (PAC), will be carried out: a 8 KWp three-phase fixed topology, 1 kWp fixed single phase and 1 kWp traceable single phase. These photovoltaic systems are power electronics based devices, such as inverters constructed from semiconductor switches, which, due to their construction and operation, affect the waveform of the electrical voltage and current, deteriorating the QEE. From the analysis of PQ indices, obtained by means of discrete Fourier transform (DFT), for power characteristics, voltage and current harmonics, imbalanced levels among system phases and power factor regulation, an analysis of the impact generated by the photovoltaic plant at its point of connection with the utility grid will be performed. The indices will be analyzed and compared to the standards established by the Institute of Electrical and Electronics Engineers (IEEE) in order to evaluate the impact caused by the connection of the photovoltaic system at the PAC.

16
  • FABIO FONSECA DE OLIVEIRA
  •  

    Efficient 3D object recognition using multifoveated point clouds

     

  • Advisor : RAFAEL BESERRA GOMES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • BRUNO MARQUES FERREIRA DA SILVA
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • ROBERTO TEODORO GURGEL DE OLIVEIRA
  • Data: Jul 3, 2017


  • Show Abstract
  • Technological innovations in the field of hardware and RGB-D sensors allowed real time 3D point clouds acquisition. As a consequence, varieties of interactive applications related to the 3D world, that have been receiving increasing attention from researchers, arisen. However, one of the main problems that still remains is the  computationally intensive processing that requires optimized approaches to deal with this  3D vision model, especially when it is necessary to perform tasks in real time. Thus, we started from a proposed 3D multiresolution model presented as foveated point clouds which is a possible solution to this problem, but is limited to a single foveated structure with context dependent mobility. In this way, our proposal is an improvement of this model with the incorporation of multiple foveated structures. However, the union of several foveated structures results in a considerable increase of processing, since there are intersections between regions of distinct structures, which are processed multiple times. We address this problem by using a proposed multifoveated model that regards intersections on the union procedure. Such approach can be used to identify objects in 3D point clouds, one of the key tasks for automation, with efficient synchronization, allowing the validation of the model and verification of its applicability in the context of computer vision. The results demonstrate a gain in performance of the proposed model in relation to the use of multiple structures of the foveated point cloud model.

17
  • TIAGO FERNANDES DE MIRANDA
  • PERFORMANCE ANALYSIS OF CAUSALITY INDICATION METHODS APPLIED TO INDUSTRIAL ALARMS

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • CELSO JOSÉ MUNARO
  • Data: Jul 3, 2017


  • Show Abstract
  • Industrial alarms are fundamentals tools for maintenance of safety and health from complex industrials process, between monitoring of thousands of process variables, the operator’s role is reduced to work on demand of alarms occurrence. However, an industrial alarms system poorly designed becomes inefficient against industrial abnormality situation. Among the possible degrading agents of an alarm system are the causal alarms, these are characterized by the difficulty of identification and by the high impact in monitoring industrial systems. Several works in the literature study possible ways of identifying causality patterns through information from industrials process; such ways are based in statistics and/or mathematical metrics to obtain the results. In this work, the performance of two causality indication methods applied to industrial alarms was analyzed, namely: Cross-correlation and Granger causality test. As alarm data have a discrete characteristic on the time, it was necessary to perform a preprocessing on them, via a signal smoothing technique, before applying both methods. To validate the methods under study, industrial alarms data from simulation scenarios of alarms generation with very realistic characteristic were used. Lastly, industrial alarms data from Tennessee Eastman Process benchmark were used as real application results. Therefore, the results indicate that, in general aspects, the Granger causality test performed a greater efficiency than the cross-correlation in the task of indication causal relations between industrial alarms.

18
  • DANNILO MARTINS CUNHA
  • Software Architecture for Continuous Evaluation of the Teaching-Learning Process

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • RUMMENIGGE RUDSON DANTAS
  • SAMUEL OLIVEIRA DE AZEVEDO
  • Data: Jul 3, 2017


  • Show Abstract
  • This work aims to present the structure, description and validation of a software architecture that has the capacity to enable the construction of tools whose main purpose is to carry out the continuous assessment of student performance in the teaching- learning process used by the teaching class during their classes. Through an exploratory methodology and in order to validate the proposed software architecture, three case studies were carried out in the 1st year classes of the computer science course of Lajes Advanced Campus of the Federal Institute of Education, Science and Technology of Rio Grande do Norte (IFRN). These case studies dealt with the subject of exponential functions of mathematics 1. Shortly after the teacher delivered the subject of exponential functions, an evaluation consisting of only a single objective question was constructed and made available to the class during an expository lesson. These students then responded to the assessment in question, allowing the teacher to generate a brief report about the class's performance in relation to the content addressed in the classroom. Once in possession of these data, the teacher was able to decide whether to carry out a review of the subject matter or to follow up the development of his discipline. In a case study, the teacher noted that he could follow up the development of his discipline. However, in the other cases, the teacher realized that he should make a brief review regarding the content addressed, since the classes had presented a very low performance. This evaluation process occurred through the use of a skeletal system developed based on the proposed software architecture. The built system was implemented through the use of web technologies in order to make it available on the Internet and, therefore, be more accessible to students, be it a notebook, tablet, smartphone or any other device that would allow access to the Internet. It can be said that this is an agile way of providing a better direction in relation to the subjects taught during the teachers' classes. In addition, the proposed software architecture gives the possibility to develop a teaching platform that includes students, teachers and even coordinators of the most diverse courses.

19
  • HENRIQUE ADLER MEDEIROS SILVA
  • ANALYSIS OF BIO-INSPIRED AND FRACTAL MICROSTRIP ANTENNAS

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • JOSE PATROCINIO DA SILVA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • VALDEMIR PRAXEDES DA SILVA NETO
  • Data: Jul 5, 2017


  • Show Abstract
  • Bio-inspired engineering is an interdisciplinary field of research, which includes specific areas such as: biology, engineering, physical sciences and biomimetics. The multiple and successful applications, in modern systems engineering inspired by biology's own mechanisms, have encouraged telecom researchers to use bio-inspired engineering to improve wireless communication systems. In this sense, this dissertation tries to investigate the applications of the natural anatomy of the leaves of the plants in microstrip antennas. In addition, a fractal antenna of multiband operation is presented, with a model created from an iterative function, known as the Tree of Pythagoras. The antennas are simulated on a fiberglass/epoxy FR-4 substrate with a dielectric constant of 4.4 and thickness of 1.57mm. The structures are analyzed using Ansoft Designer software, which implements the method of moments (MoM). Some prototypes are manufactured and measured using a vector network analyzer, for comparison purpose.

20
  • DANIELSON FLÁVIO XAVIER DA SILVA
  • Plunger Lift Method Simulator and Comparative Study of Controllers

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • OSCAR GABRIEL FILHO
  • Data: Jul 10, 2017


  • Show Abstract
  • This work aboard the artificial lift method named plunger lift that is used in wells with
    low reservoir pressure. This method uses a mechanical plunger to help the oil lift from the
    bottom of the well to the surface through the well closing and opening with different time
    interval. The plunger lift has some stages that, when concluded, complete a cycle. It was
    developed a simulator in Java with mathematical model created in the AUTOPOC project
    developed at LAUT in C++ language. It were implemented two types of controls for this
    method: time control and control by casing pressure. In the end, results are obtained
    with the simulator and then compared for detailed analysis and take conclusions about the
    efficiency of the implemented controllers.

21
  • AMANDA LUCENA GERMANO
  • Performance evaluation of data stream-oriented approaches applied to fault detection of industrial processes

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • FLAVIO BEZERRA COSTA
  • BRUNO SIELLY JALES COSTA
  • Data: Jul 31, 2017


  • Show Abstract
  • In order to increase product quality and process performance, the degree of automation has grown significantly in industries. As a result, systems are increasingly complex and are accompanied by problems that are difficult to solve due to the high dimensionality of these systems and the large amount of information flow, as well as the randomness of faults and defects. An unexpected failure can lead to operational risks, so the importance of detecting and locating the fault, especially when the industrial plant is still operating in a controllable region and it is possible to act to bring the process back to normal, safe and operational. Thus, it is desirable for the fault detection system to provide fast and reliable responses with a computational effort appropriate for real-time processing, even though it requires handling large amounts of data. In this context, data stream-oriented algorithms to outlier detection may be promising candidates for fault detection of industrial process, because they work with sequences of temporarily ordered samples. In addition, they handle well with large amount of data because they are recursive and online algorithms that do not need to store past samples. Thus, in this dissertation two algorithms of this class are analyzed, named TEDA (Typicality and Eccentricity Data Analytics) and RDE (Recursive Density Estimation), when applied to fault detection of industrial processes. Their performances are compared to R-PCA (Recursive Principal Component Analysis) algorithm. The classic Tennessee Eastman Process benchmark was used as case study to evaluate these algorithms.

22
  • GILLES VELLENEUVE TRINDADE SILVANO
  • Performance evaluation of virtual wireless networks for Internet of Things applications. 

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO HENRIQUE RAMALHO NOBRE
  • Data: Sep 4, 2017


  • Show Abstract
  • Nowadays Internet of Things (IoT) is a reality and its applications has been applied in many different scenarios, each with its own constraints and requirements. Each new IoT application developed to a specific scenario is tested and validated before being shipped on real devices for production. During the application’s validation process aspects of software, hardware and communications are evaluated. In this work we will cover the aspects of communications, since IoT devices mostly adopt wireless technologies. In this way, exists basically two validation methodologies: real testbeds or network simulators. Real testbeds is the method that provides the most accurate results as it uses real devices. However, in more complex scenarios, with high density of devices or mobility, the validation process using real testbeds is very costly. On the other hand, network simulation environments doesn’t have these constraints, being limited by the quality of mathematical models used during simulations, the resources available and by the simulator. Among the existing challenges in network simulations, incorporate techniques using real communication protocol’s code produce more accurate results compared to real testbeds. A potential solution is the virtual network simulation, in the context of this work, virtual wireless networks. The virtualization of wireless networks enable environment variables being manipulated and extended by a very low cost compared to real testbed methods. Thus, this work aims the performance validation and applicability of a virtual wireless network simulator in validation of new IoT applications with complex constraints.


23
  • SERGIO ROBERTO DANTAS
  • Proposal of a New Multifractal Structure with Low Sensitivity of Resonance Frequency with Relation to Periodicity

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • JOSE PATROCINIO DA SILVA
  • Data: Sep 6, 2017


  • Show Abstract
  • Frequency selective surfaces have received great attention from researchers around the world, due to their filtering characteristics. These structures evolved in terms of manufacturing. Thus, the geometries used, initially, were yarns in the form of a grid and later, several types of new geometries such as: rectangular, square, circular, rings, square coils, etc. were used. Recently, fractals and, more recently, multifractal elements have been employed. The use of these geometries is done in order to obtain a specific frequency response. Important parameters such as bandwidth and resonant frequency are met from the use of a given geometry. This work proposes a multifractal geometry with double similarity, which has as main characteristic low sensitivity to the variation of the periodicity with respect to the resonance frequency. This specificity will bring gain with regard to the elaboration of the project, because the control of the bandwidth is made only with the change of periodicity. Several simulations were implemented in the ANSOFT DESIGNER, for demonstration purposes, traditional structures were simulated, aiming at demonstrating the effect of periodicity on resonance frequency, and then two prototypes were constructed and measurements were made to experimentally validate the simulations.

24
  • DANIEL HOLANDA NORONHA
  • Implementation of Support Vector Machines on FPGA

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANTONIO CARLOS SCHNEIDER BECK FILHO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Nov 20, 2017


  • Show Abstract
  • Recent years have seen a dramatic increase in the importance of
    Field-Programmable Gate Arrays as compute accelerators.  Companies such as
    Amazon, IBM, Microsoft, and Baidu have started including FPGAs in their data centers aiming to accelerate their search engines. In the center of those applications are many machine learning algorithms, such as Support Vector Machines (SVMs). For FPGAs to thrive in this new role, the effective usage of FPGA resources is required. The project’s main goal is the parallel FPGA implementation of both the feed-forward phase of a Support Vector Machine as well as its training phase. The feed-forward phase (inference) is implemented using the polynomial kernel in a highly parallel way in order to obtain maximum throughput at the cost of some extra area. Moreover, the inference implementation is capable of computing both classification and regression using a single hardware. The training phase of the SVM is implemented using Sequential Minimal Optimization (SMO), which enables the resolution of a complex convex optimization problem using simple steps. The SMO implementation is also highly parallel and uses some acceleration techniques, such as the error cache. Moreover, the Hardware Friendly Kernel (HFK) is used in order to reduce the kernel's area, enabling the increase in the number of kernels per area. After the parallel implementation in hardware, the SVM is validated by simulation. Finally, analysis associated with the temporal performance of the proposed structure, as well as analysis associated with FPGA’s area usage are performed.
25
  • RUANN VÍCTOR DE ANDRADE LIRA
  • Obtaining constructive parameters for microstrip antennas using the Taguchi method of optimization

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • GUTEMBERGUE SOARES DA SILVA
  • JOSE PATROCINIO DA SILVA
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • Data: Nov 24, 2017


  • Show Abstract
  • The aim of this work is to find the need parameters for build microstrip antennas, using square and circular patch elements. For this, the optimization technique is used, through the Taguchi Method, where each parameter is defined from the desired operation frequency by the user, of the electrical characteristics of the material that will be used to fabricated the antenna (substrate thickness and constant dielectric of the material) and the definition of maximum and minimum values that the parameters can achieve.

26
  • JOÃO PAULO DE OLIVEIRA E SILVA
  • Virtual Impedance Applied for Stabilizing Distribution Power Grid Systems.

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • CECÍLIO MARTINS DE SOUSA NETO
  • Data: Nov 24, 2017


  • Show Abstract
  • Virtual impedance concept has been increasingly used in power electronics-based
    Power systems. Virtual-impedance-based control schemes provide a way of shaping
    converters dynamic profile, primarily using a circuit-oriented control concept, with the
    advantage of having no power losses. Using virtual impedances for output impedance
    control allows converters to provide auxiliary functions as power flow control, grid fault
    ride-through, harmonic compensation, and improve converter stability against different
    grid and load conditions. This master’s thesis qualifying proposes an implementation of
    virtual impedance-based control scheme on a photovoltaic system grid-connected three phase
    inverter. Different virtual impedance implementations and their functions are presented.
    The photovoltaic system considered and virtual impedance-based control scheme
    are described, and simulation results are presented. At last, preliminary experimental
    results of practical impedance implementation are presented.

27
  • MATHEUS FERNANDES TORQUATO
  • Parallel implementation of genetic algorithm on FPGA

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • RICARDO PEZZUOL JACOBI
  • Data: Dec 1, 2017


  • Show Abstract
  • Genetic Algorithms (GAs) are used to solve search and optimization problems in which an optimal solution can be found using an iterative process and using probabilistic and non-deterministic transitions. However, depending on the type of problem, the time required to find a solution can be high in sequential machines due to the computational complexity of genetic algorithm. This work proposes a parallel implementation of a genetic algorithm on field-programmable gate array (FPGA). Optimization of the system’s processing time is the main goal of this project. Results associated with the processing time and area occupancy (in FPGA) for various population size are analyzed. Studies concerning the accuracy of the GA response for the optimization of functions with one and two variables were also analyzed for the hardware implementation. The project was developed using the System Generator software (Xilinx development platform) and the Virtex-7 xc7vx550t-1ffg1158 FPGA.

28
  • MAURÍCIO RABELLO SILVA
  • Communication Network Performance Analysis for a Multi-UAV System Applied to the Scanning of Rocket Impact Area

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • PABLO JAVIER ALSINA
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • MARCELO BORGES NOGUEIRA
  • FELIPE DENIS MENDONCA DE OLIVEIRA
  • Data: Dec 1, 2017


  • Show Abstract
  • Research on Multi Unmanned Aerial Systems (Multi-UAV) is growing in recent years. Among several scientific and technical challenges, a robust data communication network is crucial for the cooperation and collaboration between the UAVs.

    The network design must take into account factors such as the purpose of the mission, trajectory and path planning, sensor data collection and energy supply. In this way, the present work presents the specification of a data communication network architecture for a squadron of Unmanned Aerial Vehicles to be used in the scanning of the rocket impact area for CLBI rocket launch center (Rio grande do Norte, Brazil).

    Thus, a study on the main characteristics of communication networks for multi-UAV systems and the specificities of the application addressed in this project is done. Two different strategies for the scanning of the rocket impact area are proposed. In order to do a comparative analysis between these strategies and to define an appropriate architecture for the application, the characteristics of the networks for multi-UAV systems that are more appropriate to them are analyzed.  

    In this context, a network architecture based on Xbee Pro 900HP S3B modules, integrated in an embedded computer hardware platform, equipped with GPS and autopilot controller board is proposed. A test plan with Xbee devices is conceived and implemented in orderto evaluate their performance in the proposed network architecture in terms of robustness, reliability and energy economy.

     

    In order to measure performance in the possible UAV squad formation scenarios, network management software is used to measure throughput, packet loss and other performance indicators in the communication links between the different nodes of the network.

29
  • ANDRE HENRIQUE MATIAS PIRES
  • Multilevel Wavelet Analysis as a Fitness Function in Controllers Tuning Using Metaheuristics

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • ROBERTO KAWAKAMI HARROP GALVAO
  • Data: Dec 6, 2017
    Ata de defesa assinada:


  • Show Abstract
  • The control of dynamic systems is a challenge, the methods traditionally used in tuning present the difficulty in expressing the desired specifications and being able to find controllers that produce these requirements, especially when the case requires more complex controllers, it is the case of  Multiple Input Multiple Output (MIMO) problems. Due to the increasing competitiveness in the industry, it becomes imperative to use more efficient tuning techniques and that in fact can find controllers with the desired performance. For this, one can use metaheuristics, such as Particle Swarm Optimization (PSO), Genetic Algorithm (AG) and Vagalume Algorithm to obtain the parameters of the controller according to a fitness function, which should in fact code how good a given controller is, adequately expressing the desired specifications, so that the metaheuristic employed can find the optimal controller, which best satisfies the chosen fitness function. Therefore, it is proposed to use the multilevel wavelet analysis, already present in the literature, focused on other applications, especially in the analysis of signals, sounds and images, for the creation of an index to be used as a fitness function in control optimization. Wavelet analysis allows to capture information on the behavior and shape of the signal by informing the frequency of a signal over time, a characteristic that may be desirable, in the evaluation and design of controllers and, thus, it is possible to separately evaluate the performance transitional and permanent arrangements. A case study will be done, finding control of a MIMO system of four coupled tanks. A comparative study was made with other fitness functions presented in the literature and with the Root Locus  method. The implemented controllers presented the expected performance, and the one found using the proposed index presented better performance.

30
  • PEDRO MAIA DE SANTANA
  • LTE/Wi-Fi Coexistence solutions for unlicensed bands

  • Advisor : VICENTE ANGELO DE SOUSA JUNIOR
  • COMMITTEE MEMBERS :
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ALLAN DE MEDEIROS MARTINS
  • ÁLVARO AUGUSTO MACHADO DE MEDEIROS
  • Data: Dec 7, 2017


  • Show Abstract
  • The objective of this master thesis plan is to perform a study on the application of LTE networks in the ISM (Industrial Scientific and Medical) spectrum and its consequent impact on heterogeneous technologies commonly coexisting in the same frequency range. Initially, a theoretical elucidation about the regulations that involve the use of unlicensed spectrum as well as the main LTE coexistence solutions in this medium is made, highlighting the mechanism recently standardized by 3GPP (LTE-LBT) and pioneering companies in the field, such as a solution from Qualcomm (the LTE-DC). As a practical elucidation of the initial theoretical investigation, performance analyzes of the respective solutions are developed using the ns-3 simulator. In the end, a solution proposal for the Carrier-Sensing Adaptive Transmission (CSAT) mechanism based on machine learning is presented. This solution aims to improve the performance of LTE-DC. In the final version of the master thesis, this adaptive solution will be compared with the classical solutions and its gain will be evidenced.

31
  • GUILHERME PEREIRA MARCHIORO BERTELLI
  • Feedback Control over Industrial Wireless Networks: A Performance Evaluation of WirelessHART and ISA100.11a Standards

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVAN MULLER
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCELO HENRIQUE RAMALHO NOBRE
  • Data: Dec 18, 2017


  • Show Abstract
  • With the rise of Industry 4.0, wireless communication is a tendency in industrial environments, saving resources and enabling the addition of new applications when compared to their wired counterparts. In this context, the WirelessHART and ISA100.11a specifications are emerging as solutions for the last mile connection. Despite their high degree of applicability, due to the nature of its technical challenges (reliability, energy consumption, fault tolerance, ensuring constant delays), industrial wireless networks used, in the majority of applications, for monitoring processes. Given the aforementioned and the conservatory tendency of the industry, the demand for evaluation and assured reliability tools on Wireless Networked Control Systems (WNCS) is imminent. Aiming to enlighten and demystify the use of wireless technology on the control loops in the industry, this work presents an overview of WNCS and a practical experiment of evaluation that enables the analysis of the behavior of typical WirelessHART and ISA100.11a networks in process control by controlling the level loop of a process station through a PID algorithm implemented in a host application. The conducted control study used the Dust-Networks SmartMesh WirelessHART Starter Kit and Nivis ISA100.11A Integration kit to establish the networks, allied to Emerson's 3051S and Yokogawa's EJX110 pressure transmitters, and assures reliability and efficiency for WNCS applications.

32
  • RAFAEL LUCAS DA SILVA FRANCA
  • Traveling Wave-Based AC Transmission Line Protection using One Terminal

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • KARCIUS MARCELUS COLACO DANTAS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • Data: Dec 18, 2017


  • Show Abstract
  • A fast protection method increases the electrical power system stability, avoids damages to system components, and reduces power quality issues effects, benefiting all the electrical power system agents. The transmission lines are extremely important to the electrical system since it connects the generation units to the consumers. Therefore, problems in the transmission system has the potential of affecting all the power system. The transmission line protection based on traveling waves proposes to be the fastest protection method. The traveling waves are high frequency electromagnetic transients that arise in the voltage and current signals after an event inception in the transmission line, as a fault. Two-terminal protection schemes based on traveling waves are easier developed and implemented than one-terminal ones, but need communication and, normally, data synchronization systems among the two line terminations, which demands costs and presents technical drawbacks. This work pretends to investigate the traveling waves protection principles and, at the end, will propose anone-terminal transmission line protection based on traveling waves with no need of a communication and, obviously, data synchronization systems.The proposal of this research includes performing the equation of the sampling frequency effects in the one-terminal protection, which was not perform until now. Furthermore, classic issues related to protection based on traveling waves, such as fault close to the line terminals and the traveling waves velocity estimation, will be detailedlyequated in order to present solutions to such problems. The research will be evaluated by means of computational simulations in a 500 kV transmission system based on Brazilian and Chinese systems with the lines modulated at distributed parameters. At the end, it is expected that a fast and reliable one-terminal transmission line protection based on traveling wave method be proposed.

33
  • FABRICIO ROOSEVELT MELO DA SILVA
  • Implantation and Development of an Industrial Automation Network and SCADA System for Purified Water Treatment Station

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • RODRIGO SOARES SEMENTE
  • Data: Dec 19, 2017


  • Show Abstract
  • This document propose the adequace of a water treatment station, through the development and implementation of an automation and supervision system aimed at the production of purified water used in the manufacture of medicines. Water is of fundamental importance in the pharmaceutical industry, it participates in the cleaning processes of materials and surfaces, as well as being used as a vehicle in formulations, requiring a series of physicochemical and microbiological specifications. The process of water purification must routinely pass through a strict quality control and must have a concise, automated and efficient industrial process, according to the current legislation. The use of automation networks and supervisory systems is far from novelty in any type of industry, however, in this case, the industrial plant under study did not use these tools. In order to reach the proposed objective, an industrial communication network was implemented between the plant equipments, through a MODBUS default network, an electric current signal instrument network and a Ethernet network. The data of readings of the equipments variables were concentrated in the master PLC, which in turn was connected to a SCADA system. This SCADA provides the operator with a panoramic view of the process, informing it in real time of the behavior of the variables from the process steps, facilitating any intervention or change in the system. The most important data is stored daily in files at the SCADA station, becoming available for future audits or during the annual validation of the station, proving the effectiveness and security of the entire system.

34
  • JESSIKA FONSÊCA FERNANDES
  • Power Transformer Differential Protection based on Support Vector Machine and the Wavelet Transform

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FELIPE VIGOLVINO LOPES
  • FLAVIO BEZERRA COSTA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • ORIVALDO VIEIRA DE SANTANA JUNIOR
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Dec 19, 2017


  • Show Abstract
  • The proposed method uses the wavelet transform to detect the beginning of some disturbance affecting the transformer, either internal or external. Whereas SVM will correctly classify the type of disturbance (internal fault, external fault and transformers energization), quickly and effectively. Therefore, SVM make the function the classifier of patterns that has the same function of differential protection of transformers, with a high efficiency in the detection of internal faults, thus avoiding inadequate relay operations in situations of external fault and transformer energization. In addition, the proposed method has an additional function, which is the classification of faults internal of transformer, which can assist in the repair and maintenance of the transformer. Therefore the proposed differential protection scheme can work in conjunction with the other system protections by sending warning signals, such as for external fault conditions of transformer, thus making the protection more reliable and intelligent.

35
  • JÚLIO CÉSAR MELO GOMES DE OLIVEIRA
  • Vehicle Soft sensor for emission monitoring of gases

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • DANIEL GOUVEIA COSTA
  • Data: Dec 19, 2017


  • Show Abstract
  • Traditionally, cities planning has followed reactive decision models based on the occurrence of problems. With the development and spread of communication and information technologies, the interconnection of electronic devices has opened a new era of data exchanging and processing, potentially supporting more efficient decisions in modern cities. This paper then proposes a software, capable of estimating the amount of carbon dioxide from existing sensor readings in vehicles, which aims to support more proactive planning and management of modern cities, addressing the problem of vehicular pollution monitoring. For that, a crowdsensing approach and the OBD-II standard are exploited dynamically extract data from vehicles to be processed and delivered. Finally, we can see that with the information obtained, it is possible to extract information about the operation of the vehicle and even make inferences about the dynamics of the vehicles in the cities, showing potential for the development of auxiliary tools for the management of urban centers.

36
  • EVERTON JOSÉ DE CASTRO REGO
  • Robustness Estimate and Autotuning of PI Controllers Embedded in Programmable Logic Controllers

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • ANDRE LAURINDO MAITELLI
  • OSCAR GABRIEL FILHO
  • PERICLES REZENDE BARROS
  • Data: Dec 22, 2017


  • Show Abstract
  • Automatic process control is a growing demand in industries that seek techniques that automate the parameterization of control systems and ensure efficiency, quality and safety. This work aims to implement a method of assessment and readjustment of PI controllers, for the system to achieve robust performance and stability in the presence of disturbances. The method is inspired by works from the literature and has two stages, the first step is to evaluate the robustness of the controller, in which its gain and phase margins are estimated. And if the robustness parameters are violated or not reached, in the second step the parameters of the PI controller will be corrected. It’s intended to program the method directly into a PLC to work together with its controller. Initially, the results are evaluated by computational simulations of the method so that it’s later passed to PLC. The experiments will be performed in real processes controlled by PLC to support the simulated results.

Thesis
1
  • FRANCISCO DAS CHAGAS DA SILVA JÚNIOR
  • Variable Structure Adaptive Pole Placement Control
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • JOSENALDE BARBOSA DE OLIVEIRA
  • JOSÉ ÁLVARO DE PAIVA
  • LEONARDO RODRIGUES DE LIMA TEIXEIRA
  • ODAILSON CAVALCANTE DE OLIVEIRA
  • Data: Feb 3, 2017
  • View Dissertation/Thesis  

  • Show Abstract
  • This work deals with the problem of designing adaptive pole placement
    controllers for uncertain, monovariable, linear and time-invariant (LTI) plants,
    both minimum and nonminimum phase plants. In the first scheme presented, called
    Variable Structure Adaptive Pole Placement Control (VS-APPC), the controller
    parameters are calculated at each instant of time from the plant parameters
    estimates, which are generated by switching laws based on the Variable Structure
    Systems (VSS) theory, and a characteristic polynomial, chosen based on performance
    requirements and which defines the desired closed-loop pole locations. The second
    scheme, called Interval Variable Structure Adaptive Pole Placement Control
    (IVS-APPC), is designed for interval plants, i.e., plants whose parameters are
    unknown but constrained within known intervals, which are common in practical
    situations where often LTI system models treated are actually approximations of
    nonlinear systems, for example, which may result in significant parametric
    uncertainties for the control systems. In the IVS-APPC design, the controller
    parameters are calculated in the same way as the VS-APPC case, but must be contained
    in intervals previously calculated by an optimization algorithm that seeks to solve
    a Nonlinear Programming problem, so to ensure that the closed-loop poles remain in a
    convex region defined by the roots of an interval characteristic polynomial whose
    stability is guaranteed by Kharitonov's Theorem. The main motivation of this work is
    the application of the proposed schemes to nonminimum phase plants, since the
    control approach known as Variable Structure Model Reference Adaptive Control
    (VS-MRAC), which has presented over the last years satisfactory performance and
    robustness results, is restricted to minimum phase plants. Simulation results are
    presented to illustrate the properties of the proposed schemes, such as fast
    transient, smooth control signal without filtering and robustness to parametric
    variations.
2
  • DANIEL LOPES MARTINS
  • Intelligent System for Assistance in the Design and Installation of a Wireless Industrial Sensors Network

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRES ORTIZ SALAZAR
  • DENNIS BRANDAO
  • JORGE DANTAS DE MELO
  • VINICIUS PONTE MACHADO
  • Data: Feb 6, 2017


  • Show Abstract
  • The advancement of technology has provided us with a significant improvement in the communication media. Nowadays we are surrounded by devices that are communicating all the time with each other using electromagnetic waves. Two major benefits of these systems are precisely the mobility provided by not using cables in their communications and ease of installation. The industrial market realized that these characteristics are very advantageous (mainly in mobile equipment and hostile environments, corrosive or in high temperatures) and began to invest in this technology with the emergence of two protocols that stand out as being open wireless communication protocols for industrial environments: WirelessHART and ISA100.11a. The WirelessHART was developed by the HART Communication Foundation in revision 7.0 of the HART protocol specification and the ISA100.11a was developed by the International Society of Automation (ISA), which started the idea of standardizing wireless industrial communication systems for both automation and control, With ISA100.11a being the first developed standard. Although wireless technology is well-known to the general population, in the industrial environment, the technology has some restrictions on its use. Determinism, latency and recovery in the loss of communication are essential characteristics for its reliability in the delivery of information. For this, the allocation of instruments and routers can positively or negatively influence the number of routes and reach of the instruments, allowing stronger signals against obstacles and / or alternative routes in case of loss of main routes. This work consists of the proposal thesis that look for, through the use of the multiobjective genetic algorithm technique, to determine the positions of the routing instruments so that the network can become as robust as possible in the environment in which it was installed. It is hoped that this work can help project engineers to more quickly and satisfactorily determine the position of the instruments maximizing system reliability as a whole, minimizing features such as signal loss and packet loss and as a consequence, process stops for maintenance of equipment.

3
  • PHELIPE SENA OLIVEIRA
  • A New Technique for Planar Circuits Optimization Inspired on the Social Behavior of Spiders

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • GLAUCO FONTGALLAND
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Feb 6, 2017


  • Show Abstract
  • Recent advances in telecommunications technology have increased the demand for lightweight, compact, and versatile microwave mobile devices. In this scenario, there has been a great deal of interest in new configurations of microwave devices and circuits, which has resulted in increased complexity in development processes, particularly for syntheses applications. To reduce these difficulties, a good alternative is the application of bioinspired algorithms in order to adapt the behavior of these new structures to the desired performance characteristics. In this context, the use of evolutionary algorithms through Genetic Algorithms (GAs), where the main objective is the survival of the strongest individuals, was one of the first successful  approaches in solving complex problems. Another aspect in evidence in recent years is the intelligence of swarms, in which individuals or agents work together for the common good. Among these, one of the main representatives is Particle Swarm Optimization (PSO). On the other hand, antennas and frequency selective surfaces (FSSs) are very important structures in communications systems, which can be optimized by the performance of the bioinspired algorithms. For the bioinspired algorithms to aid in the optimization of these structures it is necessary to implement numerical analysis techniques such as the Method of Moments or Finite Elements. Faced with the difficulty of modeling the described techniques, alternatives such as hybridization have been developed. For example, a developed solution consists of joining a bioinspired algorithm with an estimation function, such as artificial neural networks (ANNs), or with interpolation methods. Although it is possible to find desired solutions with hybridization, the estimations are performed after a training process carried out through a database that can be formed by input and output sets. Each antenna or FSS structure requires particular training databases. This work proposes an optimization technique based on the use of a bioinspired algorithm and a framework that performs the coupling of the algorithm to the commercial ANSYS HFSS software. The purpose is to perform simulation of the potential solutions during the execution of the bioinspired algorithm, and with that, to avoid the use of a database, and to make the proposed model efficient and flexible with respect to variations in the antennas and FSSs structures. Another original objective of this work is the use of the Social Spider Optimization (SSO) algorithm for solving problems in the applied electromagnetism area. The SSO algorithm is based on the intelligence of swarms and presents as differential characteristic the modeling of individuals with different behaviors among themselves, which can improve the scanning in the search space. To prove the effectiveness of the proposed technique, several antenna and FSS designs are optimized through variations in their structural parameters. Initially, it is desired to improve the bandwidth of an antenna to act as an ultra wide band. Then, the optimization of an FSS structure is performed to ensure a specific behavior in terms of resonant frequency and bandwidth. Subsequently, the proposed technique is used to improve the size reduction of a microstrip antenna using two miniaturization techniques. The results obtained in the optimization of the circuits designs are compared with those of other techniques, and good agreement is observed.


4
  • RENATA PITTA BARROS
  • CardBot - Assistive Technology for Visually  Impaired in Educational Robotics:  Experiments and Results

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AKYNARA AGLAE RODRIGUES SANTOS DA SILVA BURLAMAQUI
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • FRANCISCO MILTON MENDES NETO
  • KARLA ROSANE DE AMARAL DEMOLY
  • LUIZ MARCOS GARCIA GONCALVES
  • SAMUEL OLIVEIRA DE AZEVEDO
  • Data: Mar 9, 2017


  • Show Abstract
  • We proposes an educational assistive methodology aiming to provide the access to educational robotics activities to students with visual impairments or low vision. As an approach to soften the main issues related to this challenging problem, we introduce a low cost, assistive technology, called CardBot 2.0. Basically, this model for teaching-learning is composed by a programming environment, a mobile application, and several geometric cards, each of them representing a specific action that is recognized by the application with a tag. So, the student can program the robot by selecting and organizing geometric cards on the surface of a board or on a table. Also a contribution of this work being part of the solution, the professor can create new cards and register the respective actions and tags. This allows the professor to add new actions for the robot or even to create a new language. We validated our approach by performing experimental classes for students with different visual impairments and ages, and for students without impairment, with an analysis of the results, qualitative.

5
  • LAYSA MABEL DE OLIVEIRA FONTES
  • Munitur: A Proactive Monitoring and Evaluation System for Distance Learning Activities in Virtual Learning Environments

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • KARILANY DANTAS COUTINHO
  • ALINE DE PINHO DIAS
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • FRANCISCO MILTON MENDES NETO
  • LUCIANA SCHLEDER GONÇALVES
  • Data: Mar 10, 2017


  • Show Abstract
  • The use of Virtual Learning Environments (VLEs) in Distance Education (DE) has ge-
    nerated an increasing volume of data coming from interactions between the actors of this
    process. The distance tutor is the actor responsible for mediating the students’ learning
    process and for promoting interaction in the VLEs. The volume of data generated from
    these interactions, if properly exploited, can provide an understanding of the relationship
    of influence between the performance of distance tutors and the effective participation of
    students in VLEs. In this context, the research objective of this thesis was defined as the
    development of a proactive system for monitoring and evaluation of distance learning ac-
    tivities, through behavioral indicators in VLEs. The method used in this research was ba-
    sed on the six-dimensional Learning Analytics methodology, which defined stakeholders,
    objectives, data, instruments, external constraints and internal limitations. The analyzes
    were carried out using historical data from a technological course and ten undergraduate
    courses offered by the Secretariat for Distance Education of the Federal University of Rio
    Grande do Norte. In all, three samples were used. The first sample consisted of infor-
    mation from 38 tutors the distance and the second sample consisted of information from
    2,227 students, being that the data from the two samples belonging to 62 classes. The
    third sample consisted of information from 353 tutors at a distance, belonging to 1,281
    classes. As main results of this thesis, we have: (i) construction of a knowledge model
    (ontology) capable of mapping the existing relationships between the behavioral attribu-
    tes of the distance tutors and the effective participation of the students, through Pearson’s
    Correlation Coefficient ; (Ii) construction of a Web Service capable of processing the in-
    formation related to the attributes of the distance tutors, classifying their performances
    through the k-Means and Farthest First techniques and making recommendations based
    on the knowledge model; and (iii) creation of a plugin for Moode that allows the visu-
    alization of the data processed by the Web Service and that serves as a subsidy for the
    managers of said courses.

6
  • LUCIANO PEREIRA DOS SANTOS JUNIOR
  • IMPLEMENTATION OF A RADIAL POSITION INTELLIGENT CONTROL SYSTEM APPLIED TO AN INDUCTION BEARINGLESS MACHINE.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSSANA MARIA DE SOUZA FERREIRA
  • JOSÉ SOARES BATISTA LOPES
  • VALCI FERREIRA VICTOR
  • Data: Mar 30, 2017


  • Show Abstract
  • This paper describes the study and implementation of the radial position control of a bearingless induction motor with divided windings, using intelligent control techniques for optimizing the radial positioning. For the radial positioning, the forces controlled by the internal machine magnetic fields are used.  The proposed control methodology used to design a Fuzzy controller with proportional and derivative action, based on a set of control rules formulated in linguistic terms. All the system control is executed by a program developed in the ANSI C language on a DSP TMS320F28335 with floating-point, where two Fuzzy PD controllers are implemented for the radial positioning and six Proportional-integral type controllers for the current control loop. Finally, the simulation and experimental results of the system are presented and discussed, proving the good performance of the intelligent controllers based Fuzzy Logic for radial positioning control for driving the Bearingless-motor.

7
  • CLAUBER GOMES BEZERRA
  • Unsupervised Clustering and Classification of Data Streams Based on Typicality and Eccentricity

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • ALLAN DE MEDEIROS MARTINS
  • DIEGO RODRIGO CABRAL SILVA
  • ANDRE PAIM LEMOS
  • BRUNO SIELLY JALES COSTA
  • Data: May 24, 2017


  • Show Abstract
  • In this thesis we propose a new approach to unsupervised data clustering and classification. The proposed approach is based on typicality and eccentricity concepts. This concepts are used by recently introduced TEDA algorithm to outlier detection. To perform data clustering and classification is proposed a new statistical algorithm, called Auto-
    Cloud. The analyzed data samples by Auto-Cloud are grouped in the form of unities called Data Clouds, which are structures without pre-defined shape or boundaries. Auto-Cloud allows each data sample belongs to multiple Data Clouds simultaneously. Auto-Cloud is an autonomous algorithm, which don’t requires previous training or any priori knowledge about the data set. Auto-Cloud is able to create and merge Data Clouds autonomously as data samples are obtained. The algorithm is suitable for data clustering and classification of online data streams and application that require real-time response. Auto-Cloud also is recursive, which makes it fast and with little computational effort. The classification data process uses the measure of relevance between each sample to each data cloud created in clustering process. The class to which it belongs each sample is determined by the cloud with a higher measure relevance with respect to the sample. To validate the proposed method, we use it in a fault detection in industrial processes application. For this, we use real data, obtained from two industrial plants.

8
  • LEONARDO TELINO DE MENESES
  • Accuracy Errors Reduction in Current transformers for Electric Energy Measurement

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE BEZERRA DE MENEZES FILHO
  • MANOEL ALVES FILHO
  • Data: Jun 9, 2017


  • Show Abstract
  • This research directs efforts and proposes a solution to mitigate errors of accuracy in specific current transformers for electric energy measurement. Two solutions are developed: the first is a real-time control system that inhibits the supply of energy delivered to the CT – current transformer  by its magnetic circuit and which withdraws this energy from the control circuit and no longer from the primary current being measured, inhibiting the production of the excitation current by the energy circulating in the primary of the current transformer; the second is the development of an error compensation algorithm based on the knowledge of the physical, electrical and magnetic characteristics of the current transformer and the mass memory of the currents measured in the CT secondary, identifying the excitation current demanded in each integralization interval, compensating this current and recalculating the measured energy. Laboratory tests demonstrate the validity of the first method and algorithm applications in mass memory of CTs installed in the field and measuring electrical energy demanded by consumer unit demonstrate the validity of the second method. The theory and the practice are discussed and complement each other in the analytical, experimental and operational approaches of the field carried out throughout the research.

9
  • ÁLVARO MEDEIROS AVELINO
  • LP-P2IP: A low power consumption P2IP implementation using FPGA partial reconfiguration.

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • VALENTIN OBAC RODA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • JULIO CESAR PAULINO DE MELO
  • CARLOS ALBERTO VALDERRAMA SAKUYAMA
  • EDUARDO MARQUES
  • EMERSON CARLOS PEDRINO
  • Data: Jun 9, 2017


  • Show Abstract
  • This work uses as its basis the P2IP architecture, which consists of a coarse grain
    reconfigurable (runtime) architecture with low latency, applied to real time image processing.
    This architecture has been validated in FPGA (Possa 2013), being implemented
    with some basic image processing algorithms, such as Canny Edge Detection and Harris
    Corner Detection. The aim of the present work is to enlarge the architecture functionality
    through Dynamic Partial Reconfiguration, which consists in dividing the chip area in two
    regions: a static and a dynamic one. The latter can be reprogrammed without resetting
    the whole system. It leads to a lower dynamic energy consumption, a relevant feature if
    the system is battery powered. The variables that will be used to validate the system are
    the consumption, latency and maximum operating frequency.

10
  • JOAO MARCOS TEIXEIRA LACERDA
  • SOA-BD: Service Oriented Architecture for Biomedical Devices
  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • VALENTIN OBAC RODA
  • KARILANY DANTAS COUTINHO
  • ANTONIO HIGOR FREIRE DE MORAIS
  • JOSÉ MACEDO FIRMINO FILHO
  • PEDRO FERNANDES RIBEIRO NETO
  • Data: Jun 16, 2017


  • Show Abstract
  •  The communication of information systems with biomedical devices has become complex not only due to the existence of several private communication protocols, but also to the immutable way that software is embedded into these devices. In this sense, this paper proposes a service-oriented architecture to access biomedical devices as a way to abstract the mechanisms of writing and reading data from these devices, thus contributing to enable the focus of the development team of biomedical software to be intended for its functional requirements, i.e. business rules relevant to the problem domain. The SOA-BD architecture consists of six main components: A Web Service for transport and conversion of the device data, Communication Protocols to access the devices, Data Parsers to preprocess data, a Device Repository to store data and transmitted information, Error handling, for error handling of these information and Setup, for configuration of the architecture. For the development of SOA-BD, technologies such as the XML language and the Java programming language were used. Besides, Software Engineering concepts such as Design Patterns were also used. For the validation of this work, data has been collected from vital sign monitors in an Intensive Care Unit using the HL7v2.x standard. The tests obtained a difference of about only 1 second in terms of response time with the use of SOA-BD. For conclusive purposes, SOA-BD achieves important results such as the reduction on the access protocol complexity, the opportunity for treating patients over long distances, allowing easier development of monitoring applications and interoperability with biomedical devices from diverse manufacturers.

11
  • DANILO CURVELO DE SOUZA
  • Trend-weighted rule-based expert system with application to industrial process monitoring
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • JORGE DANTAS DE MELO
  • MARCELO LOPES DE LIMA
  • VINICIUS PONTE MACHADO
  • Data: Jun 23, 2017


  • Show Abstract
  • This thesis presents a novel technique — referred to as trend-weighted rule-based expert system (TWRBES) — grounded in the integration of two existing tools of the artificial intelligence field, expert systems (ES) and qualitative trend analysis (QTA). Main goal of this approach is to benefit of the major advantages associated with each of the techniques used, such as the ability to represent knowledge through rules and the capability to extract the behaviour and the trends of a continuous signal. The proposed methodology fills a gap between purely quantitative and purely qualitative methods, allowing to achieve results based on both the exact values and the trends of a given signal. Thus, the discussed technique allows the extraction of a certainty factor regarding a rule previously developed by an expert, ruling out the true/false logic used in classic expert systems. Such integration allows a direct purpose in industrial environment applications, especially in the intelligent automation field. The features of the proposed algorithm, particularly in terms of industrial process monitoring, are supported by simulations and experimental results based on industrial benchmark known as Tennessee Eastman Process.

12
  • DANIEL FAUSTINO LACERDA DE SOUZA
  • A Multifactor Authentication Method Based on Biometrics, Optical Interference, and Chaotic Maps

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • GUIDO LEMOS DE SOUZA FILHO
  • LEANDRO CARLOS DE SOUZA
  • LUIZ MARCOS GARCIA GONCALVES
  • RAONI KULESZA
  • Data: Jun 28, 2017


  • Show Abstract
  • The democratization of Internet access has allowed more and more companies to digitize their services. As new services are offered on the network, there is growing concern about the possibility of undue access to sensitive information from users, businesses and government. The increase in the number of attacks and theft of credentials has forced service delivery companies to develop new security solutions. In response to these attacks, user authentication mechanisms have evolved. Many services have migrated their authentication methods from one-factor approaches to multifactor approaches where the user needs more than one credential to access the system. 
     
    A novel method for user authentication based on multifactor approach is presented. For this security technique, a user authenticates into a system using a set of three characteristics related to physical, possession and knowledge factors. Biometrics authentication represents the physical factor. An optical authentication technique based on two-beam interference and chaotic maps complete the proposed scheme. In this sense, the seed of a chaotic map represents a user password corresponding to a knowledge factor and a resultant interferogram from an optical authentication technique represents the possession factor. Numerical simulation demonstrate the feasibility of our method. Moreover, we perform key space, sensibility and statistical analysis to demonstrate the effectiveness of the solution. In addition, some comparisons are made with the methods available in the literature.
13
  • VITOR FERNANDES DE BARROS
  • Application of Fractal Curves in Convoluted Elements for the Miniaturized and Angular Stable FSS Project

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • SANDRO GONCALVES DA SILVA
  • RONALDO DE ANDRADE MARTINS
  • ALFREDO GOMES NETO
  • ERICO CADINELI BRAZ
  • Data: Jun 28, 2017


  • Show Abstract
  • Frequency selective surfaces (FSS) have been used in telecommunications for various purposes ranging from the manufacture of hyper-gain antennas and subrefletors to its use as blocking signals in prisons. The possibility of coupling them to microstrip antennas and waveguides, and its enormous potential to cope with the arising problem of interference within communication systems, make them even more attractive to the market. The aim of this study is to describe and analyze a FSS multiband behavior, with independent of polarization and angular stability, which is a result of combining different miniaturization techniques, such as fractalization and the use of convoluted elements, so as to make it more compact, lightweight and efficient. The results are then obtained with commercial software Ansoft Designer, used for analyzing the behavior of FSS electromagnetic fields through the Method of Moments (MoM). To achieve this, in this thesis, it is previously conducted a bibliographic study of the FSS and monofractal geometry. This work also describes the main miniaturization techniques available in the literature, detailing the effects, benefits and disadvantages of each one with respect to the response of the structure.

14
  • PAULO HENRIQUE LOPES SILVA
  • A System Architecture for Creating, Scheduling, and Provisioning Distributed Robot Teams for End-User Interaction

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • ORIVALDO VIEIRA DE SANTANA JUNIOR
  • ANDERSON ABNER DE SANTANA SOUZA
  • FRANCISCO DE ASSIS PEREIRA VASCONCELOS DE ARRUDA
  • Data: Jul 4, 2017


  • Show Abstract
  • This work addresses the problem of programming, control and availability of distri- buted robots teams. Systems based on robots working together collaboratively has been the subject of much research in recent years. Due to the rapid spread of technologies in mobile devices and the Internet, as well as the benefits that robotics adds to various applications, the tendency is that it is increasingly present in the most varied activities of humans. For distributed robots systems there is a latent need for research to enable the use of such systems by end users with no or almost no experience with programming or robotics. Thus, this paper proposes a system architecture that allows the creation and programming of robot teams, allowing and users to manage them as a single system and simple way using collective knowledge acquired both programmers as of the and users. The tests are divided into three case studies with well-defined objectives. The first case study contains experiments with two different robot teams and aims to present and verify the functioning of the system during the creation, programming and availability of the functions of these teams. The second, has two experiments and aims to present and verify the operation of the system in the perspective of programming and availability of tasks. The third case study contains an experiment with a robot team. The validation of the concepts of the architecture in the perspective of the interaction of the end user with this robot team occurs through a usability test. All experiments are performed through an application (software) that implements the concepts of this architecture. It offers a set of special operations that enable end users to connect, create, and schedule robot teams. The results that are presented show that the concepts proposed by this system address fundamental aspects of this area, such as modularity, flexibility and ease of access for end users.

15
  • CARLA DA COSTA FERNANDES CURVELO
  • An Automatic Evaluation Methodology for Educational Robotics Classes

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUCIANE TERRA DOS SANTOS GARCIA
  • AKYNARA AGLAE RODRIGUES SANTOS DA SILVA BURLAMAQUI
  • RENATA PITTA BARROS
  • SAMUEL OLIVEIRA DE AZEVEDO
  • SARAH THOMAZ DE SA ROSSITER
  • Data: Jul 14, 2017
  • View Dissertation/Thesis  

  • Show Abstract
  • The process of teaching educational robotics involves not only the creation of a robot, but also the use of it for conducting an interdisciplinary activity. The use of robotics in the classroom raises an issue: how will students be evaluated in the concepts that involves educational robotics topics? We developed a methodology of evaluation of educational robotics classes. Based on researches with robotics teachers and the knowledge of this research team about the area, we raised evaluation criterias relevant to this area of education, considering the topics of an educational robotics class that should be evaluated: robot assembly, robot programming and the resolution of the interdisciplinary proposed activity. With this objective, we defined six evaluation criteria that can be applied at the teacher's discretion. However, we recognize the challenge of applying an evaluative methodology in educational robotics classes, because it requires a lot of time and effort from the teacher, who must be attentive to all the steps of the robotics class, and apply the evaluation criteria to all students. With the objective of assisting the teacher in this task, we inserted this evaluation methodology in an educational robotic simulator, allowing the simulator to perform the evaluation automatically, providing the teacher with only the results of the same. The teacher is still responsible for defining all the evaluative criteria, but the simulator is responsible for analyzing the student as he performs an activity and assigning grades to the student considering the criteria defined by the teacher. Finally, to validate the evaluative methodology, tests were performed with robotic teachers, in which teachers should register the evaluative parameters of some activities and analyze the results provided by the simulator as the students performed these activities. The results show that teachers are interested in using this methodology and believe that the proposed evaluation criteria are of great importance for an educational robotics class.

16
  • YÁSKARA YGARA MENESCAL PINTO FERNANDES
  • Eileithyia: Telehealth architecture expert on the classification of high-risk pregnancies in primary health care
  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ANTONIO HIGOR FREIRE DE MORAIS
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • BRUNO GOMES DE ARAUJO
  • JOSE EDVAN DE SOUZA JUNIOR
  • MARIA DA CONCEICAO DE MESQUITA CORNETTA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Sep 6, 2017


  • Show Abstract
  • Currently Telehealth is being applied and expanded in the Unified Health System (SUS), with emphasis on primary health care (PHC). Thus, using modern information and telecommunication technologies (ICT), such as computer networks, fixed and mobile telephony, as a strategic resource to optimize the health system as well as for assistance, administrative and educational purposes in health. Considering the global context of the use of telehealth, it has shown advances in ICT, providing new forms of transmission of knowledge and care on health. However, the Brazil women's health has been recognized as a priority; however, there has been a high number of deaths of women and children from complications of pregnancy and childbirth. Of these deaths can be prevented with the improvement in prenatal care and agility in recognizing signs of trouble in pregnancy. Thus, efforts have been made to equip the Basic Health Units (BHU) with technologies that can contribute to better access to information and aid decision making, in order to support the achievement of proper care. Lately, it has observed a deficiency in optimizing the care of pregnant women in UBS, the municipalities and thus causing overcrowding in reference maternities. Whereas many cases are diagnosed as low-risk pregnant women, including normal childbirth indication and that when there is no vacancy in the municipal network, reference maternity making call, which moves away from your user profile, which is the service high-risk pregnant women. So, if there was structure to meet those women in UBS, regional and municipal hospitals of origin, which optimize the work of health professionals, referral index inside the patient would be reduced and, consequently, would be experienced an improvement in service and costs. Accordingly, researches have been developed which generally address some problems which are pertinent to health and which can be automated, such as systems for screening patients; use of technology to improve the level of: security, communication, usability, reliability and performance of applications; defining new environments and technologies for health care through telehealth. It is in this context that the present research doctoral thesis proposes to develop an intelligent architecture that automates the process of regulation for the referral of patients with high-risk pregnancy between the reference municipalities and motherhood. And thus classifying high-risk pregnant women based on intelligent knowledge (in this case an expert system based on rules and using fuzzy logic for data classification) and forward them to motherhood through telehealth platform, assisting health professionals in decision-making.

17
  • NICHOLAS DE BASTOS MELO
  • A Method for Generating Angular Trajectories for Joints of an Active Orthosis Using Gait Modeling

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • PABLO JAVIER ALSINA
  • ANSELMO FRIZERA NETO
  • EDUARDO OLIVEIRA FREIRE
  • Data: Sep 6, 2017


  • Show Abstract
  • In this work, we propose a method able to find user-oriented gait trajectories that can be used in powered lower limb orthosis applications. Most research related to active orthotic devices focuses on solving hardware issues. However, the problem of generating a set of joint trajectories that are user-oriented still persists. The proposed method uses principal component analysis to extract shared features from a gait dataset, taking into consideration gait-related variables such as joint angle information and the users anthropometric features, used directly in an orthosis application. The trajectories of joint angles used by the model are represented by a given number of harmonics according to their respective Fourier series analyses. This representation allows better performance of the model, whose capability to generate gait information is validated through experiments using a real active orthotic device, analysing both joint motor energy consumption and user metabolic effort.

18
  • ADJAIR FERREIRA BARROS FILHO
  • Study and Construction of an External Rotor Induction Motor Small Size Used as Bearingless Motor

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • JOSSANA MARIA DE SOUZA FERREIRA
  • RICARDO FERREIRA PINHEIRO
  • JOSE ALVARO DE PAIVA
  • JOSÉ SOARES BATISTA LOPES
  • Data: Oct 9, 2017


  • Show Abstract
  • This thesis aims at the study and construction of a prototype of a small three-phase induction motor (28.6 mm outside diameter and 15 mm height), with the external squirrel cage-type rotor being used as a Bearingless. This study started using a conventional Brushless motor and was adapted to function as an external rotor induction motor. The bearingless induction motor uses the split winding configuration to achieve radial positioning and torque. Simulation studies were performed using the Finite Element Method (FEM), effectively showing that it is possible to control the radial position and torque to keep the rotor spinning. A first prototype was successfully built and tested for a power of 100W showing good potential for applications in this power range and size, such as those applied in artificial heart systems. The control system was implemented using the Digital Signal Processor - DSP TMS 3208F335. 

19
  • KEROLAYNE PAIVA SOARES
  • Preliminary Studies With Augmented Reality Tool To Help In Psycho-pedagogical Tasks With Children Belonging To Autism Spectrum Disorder

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • RUMMENIGGE RUDSON DANTAS
  • AKYNARA AGLAE RODRIGUES SANTOS DA SILVA BURLAMAQUI
  • KARLA ROSANE DE AMARAL DEMOLY
  • Data: Oct 19, 2017


  • Show Abstract
  • The present thesis aims to show the efforts to develop a tool that helps children affected with Autistic Spectrum Disorder (ASD).This tool introced is based in Augmented Reality and basically consists of the display of reallife caricatured scenes, visualized through the Google Cardboard glasses, which were used in tasks and psychopedagogical tests performed with these children. We analyzed the relationships about the possible increase in executive functions when they have their facial processing smoothed using the proposed system and seeing the real world as a cartoon. This initial study provides evidences to verify that such children have a particular interest in cartoon in spite of human faces. The results suggest that the proposed environment helps to increase children’s performance in psychopedagogical tasks and that it can be a useful tool to help professio- nals in education in their work to provide better support to these children, especially with regard to development of executive functions of them.

20
  • BRUNO JÁCOME CAVALCANTI
  • Study of Prediction of Propagation Loss Models in LTE and Advanced-LTE Communications Systems Using Artificial Intelligence Techniques

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO
  • JOSE PATROCINIO DA SILVA
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • MARCOS TAVARES DE MELO
  • Data: Oct 20, 2017


  • Show Abstract
  • In this thesis is made a careful analysis of the main propagation loss models for Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A) communication networks using artificial intelligence techniques such as neural networks and genetic algorithms in environments urban, suburban and rural areas of mid-sized cities in northeastern Brazil. The methodological procedures performed initially consisted of simulation of the Hata and Ericsson 9999 models, along with their optimized versions. They were then compared with measured values obtained from a measurement campaign. The results obtained through simulations, optimizations and measurements, showed good metric agreement. The main contribution of this thesis is that by employing these improved propagation models, we can estimate propagating signals closer to reality, avoiding errors in the planning and implementation of LTE and LTE-A wireless networks.

21
  • SEBASTIÃO EMÍDIO ALVES FILHO
  • A Low Power Energy-Proportional Computing Cluster Architecture

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL VIDAL AROCA
  • ROMMEL WLADIMIR DE LIMA
  • SAMUEL XAVIER DE SOUZA
  • Data: Dec 1, 2017


  • Show Abstract
  • One of the main challenges for the so-called Green Computing is to get a better relation between the amount of work performed by the computational infrastructure and the energy consumption to maintain it, that is, a better energy efficiency. Therefore, this work presents the architecture of a computing cluster with low energy consumption that powers on or off a number of running machines automatically and dynamically. The quantity of enabled devices is according to the actual processing demand, which avoids unnecessarily powered equipment and increases the overall system efficiency. In order to carry out its development, a theoretical model is proposed, discussed, and implemented through the NPi-Cluster, a cluster composed of Raspberry Pi devices. To prove the proposed model feasibility, NPi-Cluster is used as a web server with load balancing. Data gathered shows that NPi-Cluster has adequate performance when compared to other web servers running on traditional server architectures, however with less power consumption. A 7-machine cluster running at maximum performance is able to handle more than 450 simultaneous requests, with about 1000 transactions per second. The power consumption required to do it is about 15 Watts, that is equivalent to a energy-saving light bulb or a computer in suspended mode that does not perform any task. When the requests demand is low, the power consumption is dynamically reduced until less than 2 Watts. Besides to being able to handle workloads with acceptable quality of service, the proposed cluster also provides high availability by avoiding single points of failure.

22
  • DIEGO RAMALHO MINERVINO
  • New Antennas, Filters and FSSs Configurations with Fractal Contours and Metamaterials for Microwave and Millimeter Wave Applications

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • ALFREDO GOMES NETO
  • CUSTÓDIO JOSÉ OLIVEIRA PEIXEIRO
  • Data: Dec 14, 2017


  • Show Abstract
  • In this work, new configurations of planar devices and circuits for microwave and millimeter wave applications and with fractal geometries, which are structures defined by a recurrence relationship of each point in space, are investigated and proposed. These fractal geometries are well known as set of Julia and Mandelbrot set. Specifically, we will investigate the distribution of currents on the surfaces of filter conductors, planar antennas and frequency selective surfaces (FSS) with the considered fractal geometries, for applications in both wireless communication systems and systems In the frequency range between 0.7 and 70 (GHz). Planar transmission structures such as the microstrip and coplanar waveguide lines (CPW) were considered in the development of filters and antennas with Euclidean and fractal geometries for millimeter wave applications. The choice of microstrip lines structures for the development of new antenna and filter configurations is justified by the wide application of these transmission lines in the last decades, always resulting in the manufacture of planar circuits with light structures, small dimensions, low cost, easy to build and, especially, easy to integrate with other microwave and millimeter wave circuits. The great interest in applications in the millimeter wave range is associated with the growth in the need to use the electromagnetic spectrum, the speed of transmission between circuits, such as, in the new types of computers, smartphones, smart TV and wireless, and in the reducing the components for use in millimeter and micrometric wavelengths. Initially, the study was aimed at microwave applications of the new fractals and metamaterials configurations in antennas fed by coaxial cable. In addition, the constructions and measurements of the prototypes developed for microwaves and millimeter waves were carried out in the laboratories of IST (Instituto Superior Técnico - Lisboa, PT). The simulations were carried out with the help of Ansoft Designer and Ansoft HFSS softwares. Comparisons between simulated and measured results were made to validate the work.

     

23
  • BRUNO JEFFERSON DE SOUSA PESSOA
  • The Weighted Fair Sequences Problem
  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUCÍDIO DOS ANJOS FORMIGA CABRAL
  • MANOEL BEZERRA CAMPELO NETO
  • Data: Dec 15, 2017


  • Show Abstract
  • Scheduling problems on which constraints are imposed with regard to the temporal distances between successive executions of the same task have numerous applications, ranging from task scheduling in real-time systems to automobile production on a mixed-model assembly line. This paper introduces a new NP-hard optimization problem belonging to this class of problems, namely the Weighted Fair Sequences Problem (WFSP). We present a mathematical formulation for the WFSP based on mixed-integer linear programming (MILP) as well as a series of cuts to improve its resolution via exact methods. Finally, we propose a heuristic solution method that works with much less variables of the WFSP formulation. The reported computational experiments show that, for a given time horizon, the proposed MILP-based heuristic increases the size of WFSP instances that can be tackled in practice. Moreover, its results should be considered as optimal whether a presented conjecture on the WFSP problem is proved true in the future.

24
  • RODRIGO PRADO DE MEDEIROS
  • Power Transformer Differential Protection based on the Boundary Wavelet Transformer

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MÁRIO OLESKOVICZ
  • WASHINGTON LUIZ ARAUJO NEVES
  • Data: Dec 21, 2017


  • Show Abstract
  • Currently, the differential function has been widely used in power transformer protection, leading to a reliable discrimination between internal faults and other events. However, the conventional differential protection function based on the estimation of the current phasors presents difficulties in the detection of some internal faults, such as turn-to-turn faults and turn-to-earth faults close to the transformer neutral, and dependence on the harmonic restraint and harmonic blocking functions in maintaining protection scheme security during inrush conditions and external faults with CT saturation. In order to improve the performance of the traditional methods, a negative-sequence differential element with high sensitivity has been used in association with the commom harmonic blocking and harmonic restraint. However, internal faults and other disturbances associated to the power transformer protection present transients, which can be properly detected by using the wavelet transform. This paper proposes to recreate the traditional phase and negative-sequence current differential elements by using the boundary discrete wavelet transform of the currents flowing through the secondary winding of the differential CTs. The proposed method will be evaluated from extensive simulations of internal and external faults, and transformer energizations as well. It will also be evaluated the behavior of the method in the presence of CT saturation and transformer overexcitation, the time delay obtained in the internal fault detection, and the computational burden obtained in a real-time application.
2016
Dissertations
1
  • JOSE ILTON SARMENTO SILVEIRA JUNIOR
  • Seguimento de Referência para Sistemas Lineares Incertos Sujeitos a Restrições

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSÉ MÁRIO ARAÚJO
  • Data: Jan 25, 2016


  • Show Abstract
  • Os controladores robustos, nas últimas décadas, vêm sendo muito estudados por especialistas na área de controle para tratar problemas inerentes a sistemas dinâmicos sujeitos variações e incertezas dos seus parâmetros como também perturbações. Mas além desses problemas, existe outra característica importante, que ocorre na maioria dos processos práticos, que é a existência de restrições, as quais podem resultar de limitações nos estados do sistema, na entrada de controle ou na saída. Ambos os fatores citados, se não forem tratados devidamente na etapa de síntese do controlador, podem acarretar perda de desempenho do sistema controlado ou até levá-lo à instabilidade. Neste sentido, este trabalho apresenta uma pro- posta de um controlador robusto que utiliza a teoria de conjuntos invariantes para fazer o rastreamento de referência, garantindo que o sistema obedeça às restrições a despeito do efeito de perturbações limitadas em amplitude e de variações nos parâmetros. Poliedros invariantes controlados são usados para garantir que as restrições sejam respeitadas tanto para o caso de um sistema com realimentação de estados quanto para com realimentação de saída. No primeiro caso é utilizado um procedimento de reidentificação dos parâmetros do sistema e no segundo caso um integrador, baseado no modelo do servosistema tipo 1, os quais são utilizados para reduzir o erro de rastreamento a referências constantes.

2
  • HERIC WEVERTON DOS SANTOS
  •  

    Simulation and design of miniaturized microstrip antennas with circular polarization for wireless communications systems


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Jun 27, 2016


  • Show Abstract
  •  

    Recently, the growing demand for new technologies in telecommunications has generated much attention from the scientific community. The development of RF systems, the phenomenon of convergence services in a single device and the expansion of wireless communications networks have required the development of new antennas, with low cost, small size and increasingly specific properties. In this context, planar microstrip antennas have been widely used by the industry. In certain mobile communication systems such as the Global Positioning System (GPS), the use of circularly polarized antennas has gained great emphasis, since, due to their electromagnetic characteristics, the circular polarization enables good performance even in environments subject to severe weather conditions and has small dependence on the misalignment of the transmitting and receiving antennas. This dissertation proposal is based on the analysis and development of single feed miniaturized circularly polarized microstrip antennas. Different techniques are investigated to provide microstrip antennas circular polarization and size miniaturization. In addition, based on theoretical and parametric analyses, new antennas configurations are proposed for applications in wireless communication systems. Several prototypes are built and measured for validation purpose. A good agreement is observed between the simulation and measurements results.


3
  • FRANKLIN HEBERT SILVA DO NASCIMENTO
  • Impedance Converter Supply Single Phase Operating in Isolated Mode.

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • VALENTIN OBAC RODA
  • ANDRES ORTIZ SALAZAR
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Data: Jun 30, 2016


  • Show Abstract
  • Technological advances in the past decades represent a demand of mankind for better conditions related to quality of life. All development achieved in various areas of human knowledge, almost always, is directly related to the use of electricity, is therefore of fundamental importance, the research aimed generation and ways of using the electricity generated. The work is aimed to provide the use of a source of impedânciautilizado type converter for single-phase alimentarcargas from a primary power supply, operating in isolation. a design methodology for inverter dimensioning and output fi lter and presented a simple Boost modulation technique and its variations, used in inverter drive will be displayed. In addition a new modulation technique proposed in this work will be presented. The modulation techniques for the drive drive will be evaluated by means of simulation results and experimental.

4
  • BRUNO DE MELO PINHEIRO
  • Design of Multifunctional Antennas Integrated with Frequency Selective Surfaces

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JEFFERSON COSTA E SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Jul 4, 2016


  • Show Abstract
  • This works aims to attribute the use of Frequency Selective Surfaces (FSS) togheter with plannar antenna arrays, proposing new geometrys that grant better results than the older ones, in terms of directivity, gain and bandwidth. In addition to that study it will also be made an study about the characteristics of the arrays of microstrip antennas, mutual coupling between the elements of the array, ground plane trunking with carving at the microstrip line fed, and its benefits for the for the radiation characteristics of the antenna. To accomplish that study, some results for microstrip antenna arrays with two elements, where the ground plane carving have been made, were reproduced. As soon as its effects were verified, the optimal parameters for the radiation characteristics of the antenna were selected and applied, so the new geometry of FSS could start beeing proposed on that antenna. That initial study have been made only with simulations using commercial softwares. In the following research work, it will be created at least one prototype of the best result simulation, so it can be tested and verified if it will be useful or not for the applications that it was inicially contructed for.

5
  • DAVI HENRIQUE DOS SANTOS
  • Orientation control and short distance path planning for the N-Boat sailboat robot

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • RAFAEL VIDAL AROCA
  • Data: Jul 13, 2016


  • Show Abstract
  • The main challenges in the development of autonomous sailboats are: control, path
    and trajectory planning, sensor data acquitision, and power supply. Towards this direc-
    tion, this paper introduces a study on the problems of control and path planning commonly
    found during the autonomous sailing projects. The methods developed here are to be ap-
    plied in the sailboats used in the N-Boat project, allowing them to reach targets points
    accurately and quickly, and to perform one of the must difficult tasks in sailing that is
    navigating against the wind. To achieve these goals, at first, a method to find the most
    appropriate low level controller for the desired application is developed. This method
    uses a dynamic PI controller, coming up with a table that contains the best proportional
    and integrative parameters that are appropriate to each situation according to the model
    used. A method for generation of paths in situations contrary to wind is also modeled,
    implemented and tested (in simulation). To generate the way points, this method takes
    into account two parameters: the distance available for the maneuvering and the desired
    orientation of the boat during the maneuver. An optimization method is proposed, based
    on genethic algorithm, implemented, and also tested (in simulation) for getting the con-
    troller best parameters. The method manipulate some defined parameters for generating
    paths, finding the ones that generate the path in which the boat achieves the minimum
    time to destination. Results of various simulation experiments are shown to demonstrate
    the validity and robustness of the methods developed.

6
  • CAROLINE ALBUQUERQUE DANTAS SILVA
  • Blind Adaptive Equalizer Based on Genetic Algorithms

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • DANIEL ALOISE
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RODRIGO PEREIRA RAMOS
  • Data: Jul 18, 2016


  • Show Abstract
  • This paper proposes a convex optimization scheme based on linear programming and genetic algorithms for the blind equalizers applied to digital communications systems. It arose from the growing need for improvements in communication systems in order to transmit as much information as possible in a physical environment reliably.
    The proposed scheme, ELC-GA (Blind Linear Equalizer Linear based on Genetic Algorithms), is characterized by performing blind adaptive channel equalization in fixed units of data, using a genetic algorithm as adaptive algorithm, whose objective function is a globally convergent constrained linear function. However, due to the random characteristics of the signal modeled with intersymbol interference and additive white Gaussian noise, the used linear function now represents a stochastic linear programming. Accordingly, the use of genetic algorithms is particularly suitable for being able to get optimal solutions covering a considerable portion of the search space, which corresponds to the various stochastic scenarios.
    This work also describes the implementation details of the proposed scheme and the performed computational simulations. In the performance analysis, the ELC- GA results are compared to the results of one of the traditional blind equalization techniques, CMA, used as reference in this analysis. The results are shown and discussed under the appropriate metric analysis.
    The conclusions of the study indicate the GA - ELC as a promising alternative to blind equalization due to its equalization performance, which reaches global convergence in a considerably smaller range of symbols than the technique used as reference.

7
  • PETRÚCIO RICARDO TAVARES DE MEDEIROS
  • Multiresolution Multifoveation using Moving Foveae

  • Advisor : RAFAEL BESERRA GOMES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • BRUNO MOTTA DE CARVALHO
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • ROBERTO TEODORO GURGEL DE OLIVEIRA
  • Data: Jul 20, 2016


  • Show Abstract
  • Foveation is a computer vision technique for visual information reduction obtained by applying an image transformation in the spatial domain to the multiresolution domain. However, this technique is limited to a single fovea context-dependent mobility. This work proposes the defintion and the construction of a multifoveated model called MMFM (multifoveamento em multirresolução com fóveas móveis) based on an earlier model called MFM (multirresolução com fóvea móvel). In the context of multiple foveae, the application of various MFM structures, one for each fovea, results in an increase in processing time, since there are intersection between regions of different structures, which are processed multiple times. Given MFM structures, an algorithm in order to get disjoint regions which are to be processed is proposed, avoiding redudant regions and thereby reducing the processing time. Experiments are performed to validate the model and to verify its applicability in the computer vision context. Results show the gain in processing time of the proposed model compared to the use of multiple MFM structures.

8
  • SERGIO NATAN SILVA
  • Development of a Real-Time Simulator for Dynamic Systems using a FPGA Platform

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • EDUARDO RODRIGUES DE LIMA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Jul 22, 2016


  • Show Abstract
  • In most cases, the development of new embedded algorithms for the automation and control of industrial plants requires real-time testing. However, the use of real plants can often involve high costs, which can prohibit the testing of new algorithms. The objective of this project was therefore to develop an embedded field-programmable gate array (FPGA) platform for the real-time simulation of dynamic systems. FPGAs are flexible reconfigurable hardware platforms that may be altered or programmed in run time. Different to commonly used processors, this reconfigurable computer enables adjustment and optimization of the hardware structures for executing specific algorithms, aiming to improve execution performance. The platform proposed here, called the Real-Time Simulator for Dynamic Systems (RTSDS-FPGA), have potential in both academic and industrial environments. In industry, the RTSDS-FPGA can be used in the optimization and tuning of embedded control and automation algorithms. In the academic field, it can be used to support research into new solutions in the area of automation and control, and as a tool to assist teaching at undergraduate and postgraduate levels. In addition to performing real-time simulations, the RTSDS-FPGA can also speed up the simulation of complex dynamic systems, due to the parallelization capacity provided by the FPGAs. This paper presents test-bench results obtained for the RTSDS-FPGA, configured to perform the real-time simulation of a longitudinal vehicle model. The results are compared with non-real-time simulations using error measurements for different route profiles. In all the tests, the RTSDS-FPGA gave satisfactory results with errors of around 5%, when compared to the non-real-time simulations. It was demonstrated that the RTSDS-FPGA provides a viable and highly efficient way of assisting the development of new control and automation algorithms.

9
  • LEANDRO ROCHINK COSTA
  • Less is more approach for balanced minimum sum-of-squares clustering

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • DANIEL ALOISE
  • DARIO JOSE ALOISE
  • Data: Aug 22, 2016


  • Show Abstract
  • After the advance in collecting and storing data and the increase on applications which are source of new information, the number of data elements available is very huge either on volume as on variety. Because the rising in the data quantity, the necessity of understand and summarize them becomes fundamental. Given a set of points, balanced Minimum sum-of-squares Clustering(balanced MSSC) aims to find subsets, denoted clusters, miniminzig the summation of squared distances from each data point to the centroid of its cluster. In this work, we present a variable neighborhood search heuristic for balanced MSSC following the recently proposed LIMA (less is more approach). Computational experiments show that the proposed heuristic outperforms the current state-of-the-art algorithm for the problem.

10
  • LUCILEIDE MEDEIROS DANTAS DA SILVA
  • Proposal of Q-learning Reinforcement Learning Technique in FPGA

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALISSON VASCONCELOS DE BRITO
  • JORGE DANTAS DE MELO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Nov 18, 2016


  • Show Abstract
  • Q-learning is a off-policy reinforcement learning technique which has as main advantage the possibility of obtaining an optimal policy interacting with an unknown model environment. This work proposes a parallel fixed-point Q-learning algorithm architecture, implemented in FPGA. Fundamental to this approach is optimize system processing time. Convergence results are presented. The processing time and occupied area were analyzed for different scenarios and various fixed point formats. Architecture implementation details were featured. The entire project was developed using the System Generator platform (Xilinx), with a Virtex-6 xc6vcx240t-1ff1156 as the target FPGA.

11
  • ROGER ROMMEL FERREIRA DE ARAÚJO
  • Optimization and Parallelization of a Sucker-rod Pumping Directional Well Simulator

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • CARLA WILZA SOUZA DE PAULA MAITELLI
  • JOAO MEDEIROS DE ARAUJO
  • RUTACIO DE OLIVEIRA COSTA
  • CALEBE DE PAULA BIANCHINI
  • Data: Dec 9, 2016


  • Show Abstract
  • Sucker-rod pumping wells, which are the most common in the oil industry, can have vertical or directional production strings. While several mathematical models have been proposed in the literature to describe the dynamic behavior of directional sucker-rod wells, the work of Costa (1995) was the first among them to combine a number of essential simulation characteristics into a unified model. Unfortunately, its computational complexity has limited its practical use up to now. In this work, several performance optimizationsare presented for the simulations of this model in order to make its use feasible. All the proposed optimizations are described in detail and their performance is evaluated under different scenarios. The results show that the execution times of the new simulator make it a viable solution. Petroleum engineers can use this simulator in high-performance computing infrastructures to optimize the design and operating parameters of directional sucker-rod pumping wells.

12
  • RODRIGO ALVES RANDEL
  • On the use of the p-median model for semi-supervised clustering

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • CARLILE CAMPOS LAVOR
  • DANIEL ALOISE
  • Data: Dec 12, 2016


  • Show Abstract
  • Clustering is a powerful tool for automated analysis of data. It addresses the following general problem: given a set of entities, find subsets, or clusters, which are homogeneous and/or well separated. The biggest challenge of data clustering is to find a criterion to present good separation of data into homogeneous groups, so that these groups bring useful information to the user. To solve this problem, it is suggested that the user can provide a priori information about the data set. Clustering under this assumption is called semi-supervised clustering. This work explores the semi-supervised clustering problem using a new model: the data is clustered by solving the p-medians problem. Results shows that this new approach was able to efficiently cluster the data in many different domains.

13
  • JOSÉ JAIME GUIMARÃES PEIXOTO NETO
  • Design of microwave absorbers using Frequency Selective Surfaces

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • JOSE PATROCINIO DA SILVA
  • Data: Dec 14, 2016


  • Show Abstract
  • With the rapid increase of wireless systems, studies involving electromagnetic wave absorbers have attracted great attention from researchers. Their applications range from indoor systems to military applications. In parallel with this growth, the increasing studies in Selective Frequency Surfaces (FSS) allow its filtering properties to be applicable in several systems such as reflecting antennas, bandpass radomes and absorbers that will be the focus of this work. This work aims to design microwave absorbers using frequency selective surfaces. The methodology consists basically of two steps: in the first phase, a theoretical and numerical analysis of FSS with the geometries used and in the second phase, the simulation and analysis of the absorbers. For the analysis will be used a commercial computer program, which provides characteristics of transmission of the structure to a flat wave with normal and oblique incidence.

14
  • RAFAEL CELESTINO DOS SANTOS
  • The interference of a Metasurface in the performance of Microstrip Antennas

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • RONALDO DE ANDRADE MARTINS
  • Data: Dec 16, 2016


  • Show Abstract
  • This work aims to present the influence of a metasurface, a special type of metamaterials, in the performace of microstrip antennas. We begin with a brief history of the antennas then we will present the microstrip antennas: definition, feeding methods and methods of analysis; and definitions and properties of metamaterials and metasurface. Finally, we will design a microstrip antenna with and without the use of a metasurface by HFSS Ansoft Designer software and make a comparative analysis of the various parameters of the antenna, such as return loss, power gain, directivity and input impedance.

15
  • JOSE BATISTA DE SALES FILHO
  • Signal conditioning integrated circuit for wire-mesh sensors applied to multiphase flow monitoring

  • Advisor : DIOMADSON RODRIGUES BELFORT
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANTONIO AUGUSTO LISBOA DE SOUZA
  • DIOMADSON RODRIGUES BELFORT
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Dec 16, 2016


  • Show Abstract
  • In the petrochemical industry, accurate control and monitoring of mixtures composed of oil, gas and water (multiphase) has led to the development of research techniques based on tomographic imaging. In order to achieve good temporal resolution, wire-mesh sensor technology has been developed over the last decade. These sensors, which are inserted inside the pipes, consist of a mesh of electrodes that perform the measurement of complex impedance of fluids. Despite the intrusive nature, multiphase flow images are generated without the use of iterative reconstruction algorithms. This work proposes an integrated circuit (IC) to perform the conditioning of a 4x4 wire-mesh sensor mesh, applied to the determination of the phase fraction in multiphase flows. The integration would reduce the size and power consumption of conditioning circuits, compared to implementations of existing systems that use discrete components. The chip is composed of the following blocks: a transimpedance amplifier, which converts currents from the sensors into voltage; A phase-synchronous demodulator that provides phase and quadrature voltage signals that are functions of the electrical properties of the fluids (permittivity and conductivity); And analog-to-digital converters, which perform the conversion of the signals to the digital domain. The integrated circuit will be designed to be manufactured using standard 180 nm CMOS technology.

16
  • CARLOS DEYVINSON REGES BESSA
  • Control Strategy with Compensation of the effects of Dead Time Applied to Higher Order Systems

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • Data: Dec 19, 2016


  • Show Abstract
  • This work considers the difficulties involved in the control of higher order systems with transport delay, where the solution adopted to mitigate the effect caused by the delay is the use of a prediction algorithm composed of the Smith Predictor techniques and Filtered Smith Predictor. Analyzing the cases where the system model used in the prediction algorithm is not perfectly identical to the real system, the presence of error in the system dynamics was observed. This error may amplify the control effort and cause premature wear of the equipment involved, in some cases leading to system instability. In this manner, the development of a tool to treat uncertainties originated from the difference between the system model and the real system, thereby reducing the effect of transmission delay of the control system, has been proposed. A software to adjust the process model and thus improve the dead time compensation was implemented.

17
  • TÁLISON AUGUSTO CORREIA DE MELO
  • A Computational Environment for Simulation of the IEEE 802.15.4 Standard in the NS-2: Extensions to the WINSS Tool

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • CARLOS MANUEL DIAS VIEGAS
  • RODRIGO SOARES SEMENTE
  • Data: Dec 29, 2016


  • Show Abstract
  • This work aims to extend the features of the simulation tool WINSS (Wireless Network Sensor Simulator), adding to it the possibility of working with: node mobility, network faults, beacon-enabled and non beacon-enabled mode,among other functionality. WINSS is a solution for the design and tests of simulations of Wireless Sensor Networks (WSNs) in accordance to the IEEE 802.15.4 standard on Network Simulator 2 (NS-2). The WINSS takes care of creating the corresponding simulation scripts (TCL scripts) and allows the configuration of important aspects such as energy model, mobile nodes model, radio propagation model and network fault model. It provides an integrated environment with NAM and XGRAPH, tools that complement the NS-2, and generates results, like throughput, delay, packets loss, packets received and energy consumption.

Thesis
1
  • EMANUELE DA SILVA RODRIGUES MONTALVAO
  • IMPLEMENTAÇÃO DE CONVERSOR DE POLARIZAÇÃO LINEAR-CIRCULAR PARA ANTENAS DE MICROFITA USANDO METASUPERFÍCIES

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JEFFERSON COSTA E SILVA
  • JOSE PATROCINIO DA SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Jan 26, 2016


  • Show Abstract
  • Este trabalho tem como objetivo propor um novo modelo de metasuperfície com célula básica simplificada, capaz de converter sinais linearmente polarizados gerados por um arranjo de antenas planar em sinais circularmente polarizados, para a faixa de frequência ISM (2,45 GHz), apresentando uma boa largura de banda de perda de retorno e de razão axial. Para poder estudar o comportamento da estrutura proposta, a metasuperfície é acoplada a três estruturas diferentes. Primeiro são feitos testes iniciais com a metasuperfície acoplada a uma antena de microfita em sua configuração simples. Em seguida a metasuperfície é utilizada acoplada a um arranjo com dois elementos do tipo patch. E posteriormente ela é acoplada a um arranjo otimizado, que utiliza um toco em sua alimentação principal, para obter um melhor casamento de impedâncias. As estruturas são analisadas numericamente através do Ansoft HFSS™ e para validar esses resultados, as estruturas são caracterizadas experimentalmente. São apresentadas as características de transmissão simuladas e medidas. Os resultados experimentais mostram uma boa concordância com os resultados simulados. A estrutura aqui proposta apresenta a vantagem de atender as características desejadas, com uma geometria simples de ser construída e utilizando um substrato de baixo custo (FR-4).

2
  • LEANDRO ANTONIO PASA
  • Contribuição ao estudo de fusão de Mapas Auto Organizáveis de Kohonen com ponderação através de índices de validação de agrupamentos

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • GUTEMBERGUE SOARES DA SILVA
  • JOSE ALFREDO FERREIRA COSTA
  • PAULO JORGE LEITÃO ADEODATO
  • TEOFILO CAMARA MATTOZO
  • Data: Feb 19, 2016


  • Show Abstract
  • A quantidade de informações coletadas e armazenadas cresce a cada dia nas mais diversas áreas do conhecimento e técnicas de mineração de dados são aplicadas a estes conjuntos de dados com o objetivo de extrair conhecimento útil. A utilização de um ou outro algoritmo, ou o mesmo algoritmo com diferentes atributos pode levar a diferentes
    resultados, devido à diversidade dos conjuntos de dados. Na busca por soluções eficientes para este problema, foram desenvolvidos métodos de comitês de máquinas. Um comitê de máquinas é um conjunto de redes neurais trabalhando independentemente cujos resultados são combinados em uma única saída, alcançando uma melhor generalização do que cada uma das redes trabalhando separadamente. A proposta desta pesquisa é combinar informações, através de comitês de Mapas de Kohonen. Os mapas auto-organizáveis de Kohonen são redes neurais utilizadas para visualização de dados, redução de dimensionalidade e classificação de dados, entre outras aplicações. Este trabalho apresenta um novo método para combinar as saídas de mapas de Kohonen em uma única saída, com ponderação através de índices de validação de agrupamentos adaptados para quantização vetorial objetivando a melhoria da acurácia de classificação.

3
  • VALDEMIR PRAXEDES DA SILVA NETO
  •  

    Análise e Desenvolvimento de Novas Configurações de Antenas, Filtros e Superfícies Seletivas de Frequência Não-Uniformes e Reconfiguráveis pelo Método WCIP Generalizado


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • CASSIO GONCALVES DO REGO
  • HENRI MARIUS GERMAIN BAUDRAND
  • JOSE PATROCINIO DA SILVA
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • MURILO ARAUJO ROMERO
  • Data: Apr 29, 2016


  • Show Abstract
  • Os sistemas modernos de comunicações demandam dispositivos com elevado desempenho de operação. Para o atendimento dessa demanda, torna-se essencial o desenvolvimento de novos dispositivos que sejam leves, de baixo custo, que apresentem facilidade de construção e capacidade de integração com outros circuitos que integram o sistema por completo. Desta forma, novas configurações de circuitos integrados de micro-ondas atraem cada vez mais a atenção dos pesquisadores, pelo bom desempenho na integração e prototipagem de sistemas de transmissão e recepção de sinais sem fio. Este trabalho propõe e detalha a aplicação de uma técnica numérica, constituída por uma formulação de onda completa, baseada no conceito de ondas eletromagnéticas e no princípio da reflexão e transmissão de ondas na interface do circuito: Wave Concept Iterative Procedurte (WCIP). O método Wave Concept Iterative Procedure (WCIP), ou método iterativo das ondas é apresentado como uma ferramenta com alto grau de precisão no estudo de circuitos planares de micro-ondas. São propostas novas configurações de estruturas de antenas, filtros e superfícies seletivas de frequência. Para antenas, são apresentadas antenas com patch fractal aleatório, nas configurações tradicionais e como monopolo. São realizadas análise da resposta em frequência dessas antenas impressas em diferentes substrato dielétricos, dentre eles materiais têxteis. Foram obtidos e discutidos resultados para frequência de ressonância, largura de banda, perda de retorno e diagrama de radiação. Foram investigadas duas configurações de filtros planares. Suas sínteses e caracterização da resposta em frequência foram apresentadas e realizadas por meio da aplicação do método WCIP. São mostrados os resultados para sua resposta em frequência. Nesta tese, são analisadas diferentes configurações de FSS, tais como: FSS com elementos fractais, reconguráveis e FSS baseadas em arranjos não uniformes de elementos. Alguns protótipos dos dispositivos propostos foram construídos e os resultados experimentais comprovaram o modelo matemático apresentado. Os resultados obtidos também foram comparados com os resultados simulados pelo Ansoft HFSS, tendo sido observada uma boa concordância entre eles.

4
  • ALESSANDRO JOSÉ DE SOUZA
  • Visual Language for Use Case Description

  • Advisor : ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • BRUNO SANTANA DA SILVA
  • CLAUDIA MARIA FERNANDES ARAÚJO RIBEIRO
  • RAIMUNDO SANTOS MOURA
  • Data: May 6, 2016


  • Show Abstract
  • In order to success during the development of a software project, it is necessary to know its requirement, whether they are functional requirements or non-function requirements (quality attributes). In that direction, the use cases have been widely adopted by both Software Engineering and Human-Computer Interaction professionals. However, its fragmented and textual form of the system description has not been enough to provide interest concerned to the user interface design. This fact has led human-computer interaction professionals to create their own methods and techniques which often go in the opposite the philosophy used by software engineers for modeling the user-system interaction. Therefore, aiming to improve the support to use case description integrated with the user centered-design, it is proposed the Visual Language for Use Case Description - VL4UCD. In this work, it is defended the use of VL4UCD during the tasks of analysis and requirement validation, of form to address, still in the initial project phase, the concerns of both groups (software engineering and human-computer interaction) about of software interactive system development.

5
  • GIOVANI ANGELO SILVA DA NOBREGA
  • Telediagnóstico em imagens de tomografia computadorizada na indicação do tratamento de câncer de pulmão: uma abordagem baseada em inteligência artificial    

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • ADRIANO MASSUDA
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • CRISTINE MARTINS GOMES DE GUSMÃO
  • CUSTODIO LEOPOLDINO DE BRITO GUERRA NETO
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • KARILANY DANTAS COUTINHO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: May 13, 2016


  • Show Abstract
  • O câncer é uma das principais causas de morte em todo mundo. Dentre os diversos tipos o câncer de pulmão é responsável por quase 1,59 milhões ao ano. Segundo a OMS até 2030 esse número irá crescer cerca de 45% em parte devido ao crescimento da população e, em parte, ao envelhecimento da população. A detecção precoce do câncer de pulmão pode aumentar a chance de sobrevivência do pacientes e reduzir os custos do tratamento. A literatura especializada afirma que a tomografia computadorizada é atual técnica de imagem mais indicada para a realização de exames que objetivam detectar nódulos pulmonares. Contudo é um exame que demanda um custo significativo de trabalho por parte dos radiologistas na detecção e determinação das características físicas dos nódulos. Visando reduzir os custos e aumentar a eficiência do processo de diagnóstico, o presente trabalho propõe um novo sistema de auxílio na determinação das características físicas dos nódulos pré detectados em exames de tomografia computadorizada. O sistema é baseado em processamento digital de imagens(extração de características textura, intensidade e estatística), seleção de caracteríscitas (Genetic Algorithm, Simulated Annealing e Recursive Feature Elimination) e um classificador de padrões (Máquinas de Vetores Suporte). O sistema foi testado com 500 exames de diferentes pacientes na qual foi possível obter 889 tumores diagnosticados e obteve como resultado a medida de Sensibilidade em torno de 97% e uma acurácia média de 89%.
6
  • IVANOSCA ANDRADE DA SILVA
  • Tomada de Decisão em Grupo e Multi-Atributos Baseada na Lógica Fuzzy Intuicionista de Atanassov Intervalarmente Valorada

  • Advisor : BENJAMIN RENE CALLEJAS BEDREGAL
  • COMMITTEE MEMBERS :
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • REGIVAN HUGO NUNES SANTIAGO
  • GRAÇALIZ PEREIRA DIMURO
  • IVAN MEZZOMO
  • MARCUS PINTO DA COSTA DA ROCHA
  • Data: May 20, 2016


  • Show Abstract
  •  Lógica fuzzy surge em 1965 com o trabalho de Lotfi Zadeh que tem por objetivo  tratar de forma rigorosa a incerteza inerente na definição de noções e  propriedades  imprecisas ou vagas presentes em diversas situações do cotidiano, como  por exemplo, temperatura alta, pendente acentuada, etc.  Para  isto, Zadeh considerou um grau (um valor no intervalo [0,1]) com que um determinado elemento pertence a um conjunto ou satisfaz uma determinada  propriedade.  No entanto, algumas críticas a esta teoria foram feitas, principalmente por causa desta teoria lidar com incertezas usando valores exatos,  o que motivou a vários pesquisadores (entre eles o próprio Zadeh) em 1975, e de forma independente, a estender esta teoria  relaxando o conjunto onde os graus tomam seus valores. Uma destas extensões, a lógica fuzzy intuicionista de Atanassov intervalarmente valorada, proposta em 1989 por Atanassov e Gargov, que usa um par de subintervalos de [0,1], um deles representa o quanto, considerando alguma imprecisão, se acredita que o elemento satisfaz a propriedade enquanto o outro descreve o quanto se acredita que não satisfaz a propriedade. Este par de graus intervalares visam capturar a hesitação e imprecisão presente ao momento de se atribuir o grau com que o elemento satisfaz a propriedade.
     
    A lógica fuzzy e suas diversas extensões, tem sido aplicada com sucesso nas mais variadas áreas, como por exemplo, medicina, engenharia, agricultura,  econômia e em administração. Em particular, uma das principais aplicações de lógica fuzzy em administração diz respeito ao apoio na tomada de decisão. Um problema típico de tomada de decisão consiste em escolher a melhor alternativa entre  um conjunto delas ou em ordenar as alternativas de melhor a pior, considerando alguns critérios a serem satisfeitos assi como a opinião de um ou mais especialistas. Os métodos fuzzy para problemas de tomada de decisão usam graus fuzzy (ou de suas extensões) para expressar o quanto uma alternativa satisfaz um determinado atributo ou critério, e alguma forma de agregar a opinião de todos os especialistas, para chegar no final a uma pontuação (que pode ser um valor numérico ou não) que permita decidir qual é a potencialmente melhor alternativa.

    Nesta tese são apresentados avanços teóricos significativos na teoria dos conjuntos fuzzy intuicionistas de Atanassov intervalarmente valorados assim como, são proposto dois novos métodos de tomada de decisão, considerando  múltiplos atributos (ou critérios) e um grupo de especialistas,  aplicação desses métodos em problemas específicos e é realizada uma comparação com resultados obtidos com outros métodos de tomada de decisão.
     
     Por outro lado, um dos  grandes problemas com os métodos ou processos de tomada de decisão é que, quando aplicado em problemas reais,  em geral,  não é possível determinar a qualidade da solução (ordenação das alternativas) obtida pelo método. De fato, diferentes métodos  de tomada de decisão  para um mesmo problema podem resultar em diferentes soluções. Nesta tese, se propõe considerar os resultados obtidos por diferentes  métodos  (independente do tipo de extensão fuzzy usada e tipo de problema de tomada de decisão) como meras evidências que podem ser usadas por  um outro método  capaz de determinar uma ordenação das alternativas que de alguma maneira  represente a fusão ou consenso desses ordenamentos de alternativas.

7
  • DIOGO HENRIQUE DUARTE BEZERRA
  • Luar-X: Extension and Generalization of Luar Templates Processing System

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • JULIO CESAR PAULINO DE MELO
  • FRANCISCO MILTON MENDES NETO
  • SAMUEL OLIVEIRA DE AZEVEDO
  • Data: May 30, 2016


  • Show Abstract
  • The Luar template processing system used in authoring NCL documents, has deve- lopment concepts based on reuse of descriptions through document templates. These development concepts can be used in the authorship of other XML-based documents th- rough the analysis, adequacy, design and creation of a new reuse infrastructure based on Luar system. This view shows the processing system of models Luar-X, a generalization and extension Luar model system. The Luar-X keeps the concepts of development of Luar system and he changes, adapts and extends the Luar system architecture to enable deve- lopment with XML-based languages. The case studies with HTML, SVG and NCL show the feasibility of this new reuse infrastructure, which makes application development and description of agile XML documents.

8
  • EDUARDO JORGE BRITO RODRIGUES
  • Antenas Planares Eletronicamente Reconfiguráveis em Frequência para Sistemas de Rádios Cognitivos


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • EMMANUEL BENOÎT JEAN BAPTISTE DUPOUY
  • HERTZ WILTON DE CASTRO LINS
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • MARCOS TAVARES DE MELO
  • Data: Jun 6, 2016


  • Show Abstract
  • A eficiência no uso das radiofrequências (RF) é um fator determinante na capacidade de qualquer sistema de comunicações móveis. O aprimoramento da utilização desse recurso escasso tornou-se intensamente relevante desde o surgimento dos primeiros sistemas móveis celulares. As tecnologias e serviços digitais tem demandado maior alocação RF para suprir requisitos de largura de banda (BW). O desenvolvimento de tecnologias emergentes baseadas em alocação dinâmica de RF tem sido apontado como uma solução para essa crescente necessidade de BW e motivação para a realização de recentes pesquisas sobre os sistemas de rádios cognitivos (CRS). Neste trabalho, são propostas antenas de banda ultra larga (UWB) para sensoriamento espectral, assim como antenas reconfiguráveis em frequência para aplicações em CRS, os quais realizam de forma dinâmica a transmissão e recepção de sinais em banda estreita (NB). Dentre os protótipos propostos, são apresentados modelos capazes de cobrir todo o espectro de 3,1 GHz e 10,6 GHz, assim como, de forma reconfigurável, cobrir essa faixa de RF em várias NB, com destaque para a frequência de 5,8 GHz. Ademais, as antenas propostas passaram por processos de otimização e síntese baseados em ferramentas de inteligência computacional quais sejam: algoritmo genético (GA), o algoritmo de otimização de enxames de partículas (PSO), assim como o algoritmo de otimização de colônia de abelhas artificial (ABC). Como resultados, foram observadas melhorias na BW e no coeficiente de reflexão das antenas. As simulações e parametrizações computacionais, assim como as análises numéricas com GA, foram realizadas com auxílio do software HFSS. Já as análises numéricas com algoritmos PSO e ABC foram implementadas em linguagem de programação Java. Para fins de validação, os resultados dessas simulações foram comparados com resultados experimentais, tendo sido observada boa concordância para os diversos protótipos de antenas planares propostas e desenvolvidas neste trabalho.

     

9
  • JONATHAN PAULO PINHEIRO PEREIRA
  • Periodic and Quasi Periodic PBG Structures in Microstrip Antennas with Unmanned Aerial Vehicles application

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE PATROCINIO DA SILVA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO CESAR CHAVES FERNANDES
  • HUMBERTO DIONISIO DE ANDRADE
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • Data: Jun 10, 2016


  • Show Abstract
  • To conduct a study of microstrip antennas, the involvement of the broad specification of the electromagnetic spectrum of physical parameters is necessary, and each antenna design requires the use of advanced numerical computation techniques for evaluating performance measures such as input impedance, pattern radiation and gain in specific frequency bands. In this respect, this work presents a study of the influence of structures PBG periodic and quasi periodic in microstrip antenna radiation properties. The main objective is to raise the characteristics of the use of this technique for applications in antennas and propose use of optimization methods for efficiency in the preparation of structures PBG. They are treated three types of microstrip antennas, with variations in the specification of the substrate PBG for periodic and quasi periodic models with six twelve symmetries. The validation of the results generated by the computer environment is achieved by manufacturing prototypes for the antenna, taking into consideration each case study, followed by performance tests of the manufactured physical device, carried out in laboratories. Algorithms have been developed to automate the assembly of models of processes used in manufacture of simulation and physical antennas. All analyzes were performed by comparing the simulated models and measurements of antennas made experimentally. designed antennas were built to operate at frequencies in the range of 5.8 GHz used in operational tests for a video streaming application in Unmanned Aerial Vehicles (UAVs).

10
  • JOSÉ SOARES BATISTA LOPES
  • Estudo e implementação da técnica de inteligência artificial para o controle de velocidade do motor-mancal com bobinado dividido utilizando o DSP TMS3208F28335

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FILIPE DE OLIVEIRA QUINTAES
  • JOSE ALVARO DE PAIVA
  • JOSE ANDRES SANTISTEBAN LARREA
  • JOSSANA MARIA DE SOUZA FERREIRA
  • Data: Jun 17, 2016


  • Show Abstract
  • Este trabalho descreve o estudo e a implementação digital embarcado em um DSP TMS 3208F28335 para o controle vetorial de velocidade do motor-mancal com bobinado dividido de 4 pólos com 250W de potência. As técnicas inteligentes: ANFIS e as Redes Neurais foram investigadas e implementadas computacionalmente para a avaliação do desempenho do motor-mancal nas seguintes condições: operando como estimador de parâmetros incertos, e como controlador de velocidade, respectivamente. Para isso, utilizou-se o programa MATLAB® e seu toolbox para as simulações e os ajustes dos parâmetros envolvendo a estrutura ANFIS, e também para as simulações com a Rede Neural. Os resultados simulados mostraram um bom desempenho para as duas técnicas aplicadas, de forma diferente: como estimador, e como controlador de velocidade utilizando ambas um modelo do motor de indução operando como um motor-mancal. A parte experimental para o controle vetorial de velocidade utiliza três malhas de controles: corrente, posição radial e velocidade, onde foram investigados a configuração dos periféricos,  as interfaces ou drivers para o acionamento do motor-mancal. Detalhes de configuração dos periféricos do DSP TMS 3208F335 são descritas neste trabalho, assim como, as interfaces responsáveis pela aquisição da corrente, posição radial e velocidade do rotor. Por último, são mostrados os resultados experimentas do motor-mancal comparando o funcionamento do controle vetorial clássico com o controle neural.

11
  • FÁBIO AUGUSTO PROCÓPIO DE PAIVA
  • Study of the Serendipity Concept as Basis for New Approaches to the Premature Convergence Problem 

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • CARMELO JOSÉ ALBANEZ BASTOS FILHO
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • GIVANALDO ROCHA DE SOUZA
  • JOSE ALFREDO FERREIRA COSTA
  • TEOFILO CAMARA MATTOZO
  • Data: Jul 1, 2016


  • Show Abstract
  • In many engineering problems, it is common to study a type of process which behaves as a dynamic system. This type of system has the peculiarity that can be modeled by a set of equations that evolves over time to represent the modeled behavior of the system. To solve these engineering problems, various methods of Bio-inspired Computing have been proposed as a solution in different contexts. These methods are algorithms known as Swarm Intelligence. Despite the relative success, most bio-inspired methods face a common problem known as premature convergence. It occurs when a swarm (or a population) loses its ability to generate diversity and, as a consequence, prematurely converges to a suboptimal solution. In literature, there are several approaches that propose to solve this problem. This doctoral thesis proposes a new approach that is based on a concept called serendipity that is usually applied in the field of Recommender Systems. A variant called Serendipity-Based Particle Swarm Optimization (SBPSO) has been implemented to assess the feasibility of adapting this concept to the new context. Subsequently, it is compared to the standard Particle Swarm Optimization (PSO) and some variants presented in literature. Sixteen benchmark functions were used to perform the various computational experiments. In all experiments, the results of SBPSO were promising and they showed a better convergence behavior, outperforming PSO and some variants in solution quality, ability to find global optimum, solutions stability and ability to restart the movement of the swarm after stagnation has been detected.

12
  • AUGUSTO CÉSAR PEREIRA DA SILVA MONTALVÃO
  • Study of Linear-Circular Polarization COnversion of Dual-Band Antennas for Portable RFID Readers Using Miniaturized Metasurfaces

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO CESAR CHAVES FERNANDES
  • JEFFERSON COSTA E SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Jul 4, 2016


  • Show Abstract
  • This work aims to propose a new structure able to convert signals linearly polarized generated by a microstrip antenna for circularly polarized signals at two operating bands (2.45 GHz and 5.8 GHz), for use in portable RFID readers, using two miniaturized metasurfaces. In order to study the behavior of the proposed structure, three different layouts are used. First initial simulation tests are made, using the first metasurface coupled to the antenna. Then, the antenna is tested coupled to the second metasurface. Posteriorly the antenna is coupled to the two metasurfaces. The structures are analyzed numerically through Ansoft HFSS™, and to validate these results, the structures are characterized experimentally. The characteristics of transmissions simulated and measures are presented. A good agreement between simulated and measured results was obtained. The structure proposed here has the advantage to meet desired characteristics in two bands of interest, obtaining excellent values of return loss wideband, as well as the axial ratio, being a simple structure to be constructed and with low cost.

13
  • CARLOS AVELINO DE BARROS
  • Energy Reduction for Parallel Applications in Multi-core Architectures

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • DIOMADSON RODRIGUES BELFORT
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • CARLOS ALBERTO VALDERRAMA SAKUYAMA
  • RAFAEL VIDAL AROCA
  • Data: Jul 13, 2016


  • Show Abstract
  • The period that lasted from the advent of microprocessors until early this century was marked by the geometric expansion of their operating frequency. If on one hand it provided continuous performance increases, on the other hand it was also responsible for a problematic growth in heating and energy consumption. In attempt to mitigate these problems, multi-core processors have been used extensively in replacement for single-core processors, offering a viable alternative to increase performance without increasing frequency. As a way of mapping energy consumption, we present the development of two sets of mathematical models for the representation of the electrical power dissipated in the processors. According to considerations we made in relation to static and dynamic parts of the power, we established an equation for the total power as a function of the operating frequency of the respective analyzed processors. We demonstrate, based on these mathematical models, that the relative energy consumption of processors can be related to parallel processing performance measures, such as speedup and efficiency. We also use the models to monitor the influence of several factors on the reduction of energy consumption in multi-core processors, such as the percentage of the parallel portion of the code, the number of cores to be used each time, the working frequency and speedup itself. Results of the analyzes confirm the theoretical predictions and alert to the possibility of improving the energy performance of multi-core processors, especially in conditions in which the factors of influence can be made flexible.

14
  • JANNAYNA DOMINGUES BARROS FILGUEIRA
  • Calculation of Optimized Parameters for the Frequency Selective Surfaces by means of Taguchi's Method

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ALLAN DE MEDEIROS MARTINS
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • ALFREDO GOMES NETO
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • Data: Jul 18, 2016
  • View Dissertation/Thesis  

  • Show Abstract
  • Frequency Selective Surfaces (FSS) belong to a subclass of metamaterial consisting of two-dimensional metallic patches. By presenting a selective frequency behavior, these structures have been applied in the microwave and communication systems fields, in addition it is a research topic by scholars. The literature defines basically the Frequency Selective Surface as a periodic arrangement of patches that displays a certain frequency filtering and it may present characteristics of a band-stop or band-pass filter, which allows the reflection or the transmission of signals in a given frequency range. The FSS are used in diverse applications ranging from microwave and antennas systems to applications in radomes and satellite communications. Researchers have studied FSS structures with appropriate electromagnetic behavior. However, the analysis of spectral characteristics of these structures requires technique with high computational complexity. In order to reduce the computational effort related to the time of processing, it may be used optimization techniques. Concerning to it, this study proposes the use of an optimization method in the FSS design. Optimization methods are intended to get the best results of a system by tuning of the input parameters, that is, when these parameters are adjusted, the optimization methods seek a better output result so that the system performance, in terms of quality, cost and efficiency can be improved. These methods can be applied in various areas. Currently, in the Electromagnetism area, the microwave circuits and antennas have applied various optimization techniques like genetic algorithms (GA), Artificial Neural Networks (ANN) and Particle Swarm Optimization (PSO). The optimization method described in this research was developed based on the concept of the Orthogonal Arrangement, Taguchi Method. This method provides an efficient way to choose the project parameters in a process of optimization and it effectively reduces the number of experiments required in the application. Taguchi method is successfully applied in the chemical engineering and mechanical engineering fields and recently, there have been applications in the Abstract Electromagnetism area, however, its application in FSS is unprecedented. In this study, it was applied the Taguchi Method in three structures of FSS: Square FSS, Square with grid FSS and Cross Dipole. The purpose of the method is to obtain the best values for physical parameters of the FSS, so that is operating in a satisfactory manner, in accordance with certain specifications in the project. It was also used in this research the Equivalent Circuit Method. The accuracy of Taguchi Method is verified experimentally and it is compared to the simulations performed in the ANSYS Designer ®. Then, the prototypes are built and measured in order to validate the experimental results.

15
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • One Cycle Control Applied Photovoltaics on Autonomous Systems in a DC Microgrid

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ALBERTO SOTO LOCK
  • PAULO VITOR SILVA
  • Data: Jul 22, 2016


  • Show Abstract
  • The integration of units with primary energy sources, energy storage and loads, is expected to play a promising role in the future for the electricity supply. The interconnection of such units providing medium and low voltage makes a microgrid system. The distributed energy sources are the basic units for storage and distribution in microgrids. These sources can be of a hybrid type, which includes a primary energy source and storage simultaneously. A hybrid type proposed in this paper consists of a DC-DC Buck-Boost converter that tracks the maximum power supplied by a photovoltaic panel, a DC-DC Boost converter that regulates the microgrid DC bus voltage and a DC-DC bidirectional Buck-Boost converter that controls the energy flow in the system, charging or discharging a battery bank. The control of these converters should consider the protection of the battery against voltage transients and spikes, as well as the protection of loads connected to the microgrid main bus when the battery supplies the stored energy. Conventional control techniques used on the converters of these units use the pulse width modulation, which has the disadvantage of produce undesirable transient due to the slow response to changes in the system input source, or the loads resistance connected to microgrid the main bus. These transients can damage other loads and batteries connected to the microgrid main bus. Thus, one-cycle control technique is applied to the switching converters to allow fast response to transient without overshoots and zero steady-state error. The objective of this work is to use this technique in controlling these converters in order to quickly track the maximum power point of the photovoltaic panel, charge the batteries when they are discharged, and provide power from the batteries to the loads when needed, ensuring the protection of the batteries and the loads connected to the microgrid main bus.

16
  • LEONARDO RODRIGUES DE LIMA TEIXEIRA
  • Indirect Dual Mode Adaptive Robust Controller (IDMARC)
    
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • CAIO DORNELES CUNHA
  • JOSENALDE BARBOSA DE OLIVEIRA
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • JOSÉ ÁLVARO DE PAIVA
  • Data: Jul 27, 2016


  • Show Abstract
  • In this work is proposed the Indirect Dual Mode Adaptive Robust
    Controller (IDMARC), which combining the typical transient and robustness
    properties of Variable Structure Systems, more specifically of Indirect
    Variable Structure Model Reference Adaptive Controller (IVS-MRAC), with a
    smooth control signal in steady-state, typical of conventional Adaptive
    Controllers, as Indirect Model Reference Adaptive Controller (IMRAC). Due
    to use the indirect approach it provides a more intuitive controller design,
    based on physical plant parameters, as resistances, inertia moments,
    capacitances, etc. Stability analysis, based on Lyapunov Theory, are
    presented for the ideal case and considering bounded input disturbance,
    moreover simulation results. Furthermore in this work is proposed the
    Indirect Binary Model Reference Adaptive Controller (IB-MRAC) too, that
    was the first controller attemptting to act as IMRAC as well as IVS-MRAC,
    depending on fixed adaptive gains defined in the design.
17
  • ALMIR SOUZA E SILVA NETO
  • MICROSTRIP ANTENNAS FOR 4G, 5G AND CYLINDRICAL ANTENNA ARRAY

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO CESAR CHAVES FERNANDES
  • JEFFERSON COSTA E SILVA
  • OTÁVIO PAULINO LAVOR
  • Data: Aug 22, 2016


  • Show Abstract
  • Nowadays there is a breakthrough in the aerospace area, telemetry system, remote sensing, radar system (tracking and monitoring), satellite communications systems and new technologies for voice and data communications. Thus, this work presents a study about microfitas antennas for 4 g, 5 g technologies with applications in the 28 GHz frequency and 60 GHz, resonator spiral loop for applications in UWB (Ultra Wide Band) with bands and rectangular and circular cylindrical antennas for telemetry and satellite operating in the range of 2 to 4 GHz in s. studies in antennas are made, such as: application of EBG structure (Electromagnetic Band Gap) on the substrate and the ground plan, using metamaterial substrate, application of DGS structures (Defected Ground Strutures) in land plan and arrangements, with the objective of obtaining improvement in the parameters, in particular gain and bandwidth. The analysis of the dimensions of the antennas are developed using the method of the Transverse transmission line (LTT) which is a method of rigorous analysis in the spectral domain. Various simulations and measurements of antennas proposals are carried out so that the measured values are compared with the simulated values, aimed at the validation of the prototypes. In the end, are presented suggestions for the continuation of this work.

18
  • HAULISSON JODY BATISTA DA COSTA
  • Massive detection method for S-MIMO systems using the modified Richardson method in graphic acelerators.

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • VALENTIN OBAC RODA
  • SAMUEL XAVIER DE SOUZA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • FRANCISCO RODRIGO PORTO CAVALCANTE
  • JOSÉ MARCELO LIMA DUARTE
  • Data: Aug 22, 2016


  • Show Abstract
  • The evolution of wireless communications must support multiples devices and maintain high-speed data transmission. The emerging Large-Scale MIMO techniques allows improving the capacity for the next generations of communications systems. Although the benefit of multipath, which involves the antenna gain or spectral efficiency, the computational complexity of MIMO detection becomes prohibitive in large systems. Seeking to overcome it, we propose to adapt the Richardson iterative method to the LS-MIMO with random matrices theory by concepts of Marchenko-Pastur. This method requires restricted conditions for the linear resolution that limits its applications. However, the channel knowledge allows establishing adaptations that supply the requirements of the method. The channel effect explained by Marchenko-Pastur allows associating the stability of the process with an increase in the numbers of antennas that contributed to improved the convergence and reduction the iterations. Furthermore, the shared execution with correction and decoding blocks provide a workload distribution that surpasses the throughput of others detections. The results achieved from the comparative analysis of other proposals showed an unprecedented way to increase capability on the large scale detection and provides an efficient parallel processing. Also, the proposal demonstrated a level of adaptability that allows diversifying the association between performance and complexity. Therefore, the implementation of Richardson detection establishes that the transmission rate is comparable with other projects and the increasing of 1.74db SNR improve 150% at throughput. Based on this approach, the execution shows a significant increase in concurrent transmission capacity when implemented on GPU. Also, the implementation shows scalable aspects that allow increasing the performance to Gb/s by insertion of others parallels devices (GPUs) in the system.

19
  • ERNANO ARRAIS JUNIOR
  • Signal Analysis System for Cardiac Application Telecardiology
  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ALLAN DE MEDEIROS MARTINS
  • CUSTODIO LEOPOLDINO DE BRITO GUERRA NETO
  • GLAUCIO BEZERRA BRANDAO
  • ANTONIO HIGOR FREIRE DE MORAIS
  • VINICIUS SAMUEL VALERIO DE SOUZA
  • Data: Aug 26, 2016


  • Show Abstract
  • Cardiovascular problems are among the leading causes of mortality in the World. It is estimated that about 15 % of the world population has died due to cardiovascular problems. In Brazil this number represents almost 30 % of deaths, being the men the most affected by cardiovascular disease, with a percentage of approximately 60 % of the victims. Another alarming factor is that Brazil is among the 10 countries with the highest rate of death from cardiovascular disease. Cardiovascular diseases arise from malfunction of the heart and arteries, the most common are infarction, stroke, cardiac arrhythmias and ischemia. Thus, if a good monitoring cardiac activity is necessary in order to prevent possible inconvenience arising from cardiovascular disorders. In recent years, several solutions in the framework of Telecardiology have been discussed to reduce these numbers, in addition to proposing a better monitoring of individuals (patients) and aid to basic health care units located far from major centers. In this work, It is proposed a system will for ECG signal analysis applied to Telecardiology, aiming to validate cardiological clinical data, specifically cardiac arrhythmias (bradycardia, tachycardia and premature ventricular contraction). The mathematical tool used for analyzing ECG signals is Redundant Discrete Wavelet Transform (RDWT), implemented a version for real-time analysis, and the method used for measuring the ECG characteristics is the method based on thresholds. Then, with this ECG signal characterization system it can validate cardiological clinical reports, or rather, it is a tool to support of medical diagnostics validation. The results were satisfactory, the system showed Sensitivity and Positive Predictivity above 99%. It will be presented also a study about mothers wavelet that are more appropriate in ECG signals processing.

20
  • SARAH THOMAZ DE SA ROSSITER
  • W-Educ: A Complete and Dynamic Web Environment for Ecucational Robotics

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • ANDERSON ABNER DE SANTANA SOUZA
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • ROSIERY DA SILVA MAIA
  • TIAGO PEREIRA DO NASCIMENTO
  • Data: Aug 29, 2016


  • Show Abstract
  • This paper proposes a web environment for educational robotics, which is an open, dynamic and complete solution to assist in the teaching-learning process in this type activity. The environment allows different robotic platforms are programmed through the registration of programming languages with their low level functions using an intermediate language with a high level of abstraction. The system can be used by any user with or without programming experience, through a language with simple text commands. This work provides, then, a full web system that can be used to facilitate the teaching/learning process using educational robotics. In addition, for validation purposes this work includes a homogeneous method for evaluating educational software for robotics, which validated the developed tool through experiments that have assessed its didactical use and its features and compared with other tools.

21
  • ODAILSON CAVALCANTE DE OLIVEIRA
  • Control with Dual Mode Adaptation Using a RBF Network
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • CAIO DORNELES CUNHA
  • JOSENALDE BARBOSA DE OLIVEIRA
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • JOSÉ ÁLVARO DE PAIVA
  • Data: Sep 1, 2016
  • View Dissertation/Thesis  

  • Show Abstract
  • This work presents a control strategy using a network with radial basis function (RBF network) with adaptation in dual mode. The objective of the strategy is to use the approximate capacity of the RBF network to control nonlinear systems with unknown parameters or with uncertainties. The proposed control uses the structure of Model Reference Adaptive Control (MRAC) and a RBF network whose parameters are adjusted in real time in dual mode, which will allow a fast transient and a smooth control signal in steady state. The dual mode adaptive method of RBF network parameters uses the hyperbolic tangent function, which during the transient provides a similar behavior to variable structure control, and integral laws of MRAC that are regulated by a hyperbolic secant function during steady state. A hyperbolic tangent is used instead of signal function what reduces the chattering phenomenon. A hyperbolic secant is used to regulate the integral law, increasing its effects on steady state and reducing on transient time. It is presented a Lyapunov proof for dual mode method and comparisons through simulations.

22
  • NIELSEN CASTELO DAMASCENO DANTAS
  • New strategies to fix degeneracy in the k-means algorithm

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • DARIO JOSE ALOISE
  • MARIÁ CRISTINA VASCONCELOS NASCIMENTO ROSSET
  • Data: Oct 5, 2016


  • Show Abstract
  • The k-means is a benchmark algorithm used in cluster analysis. It belongs to the
    large category of heuristics based on location-allocation steps that alternately
    locate cluster centers and allocate data points to them until no further
    improvement is possible. Such heuristics are known to su er from a phenomenon
    called degeneracy in which some of the clusters are empty, and hence, out of
    use. In this thesis, we compare and propose a series of strategies to circumvent
    degenerate solutions during a k-means execution. Our computational
    experiments demonstrate that these strategies are e cient leading to better
    clustering solutions in the vast majority of the cases in which degeneracy appears
    in k-means.

23
  • EDWIN LUIZE FERREIRA BARRETO
  • Analysis of the Coupling of Fractals Structures in Multi-Band Monopole Antennas for Wireless Communications

     

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO
  • HERTZ WILTON DE CASTRO LINS
  • HUMBERTO DIONISIO DE ANDRADE
  • MARCOS TAVARES DE MELO
  • Data: Nov 18, 2016


  • Show Abstract
  • This work has as main objective to make the design and analysis of different structures for planar microstrip antenna with partial removal of the ground plane with the use of fractal curves. Recently, studies show that some parameters, such as the shapes of the antenna patch and the ground plane when geometrically altered, producing changes in the distribution current density of the planar structure and therefore the resonant modes, the radiation characteristics and polarization antenna. This paper presents a novel fractal antenna using the technique of insertion fractal slots and defects in the ground plane and discontinuities ¼ transformer wave transmission line in order to increase the bandwidth and insertion in line power for three specific behaviors frequency band applications. We used the FR4 substrate with dimensions of 85.0 x 85.0 x 1.57 mm³. In addition, we used different modes of impedance matching in line antenna feed as CPW (Coplanar Wave Guide), to change the width of the transmission line in order to obtain a variation in the current distribution and hence the response bandwidth for impedance S11≤10 dB for C band (3.9 GHz - 6.2 GHz) and S band (2.0 GHz - 4.0 GHz). An analysis is performed for the antenna feed in cases of microstrip and CPW line when circularly polarized antenna is obtained. Good agreement was obtained between measured and simulated results. The fractal antenna microstrip proposal can be easily designed, built and is a strong candidate for use in mobile communication systems in bands C and S.

24
  • ÁDLLER DE OLIVEIRA GUIMARÃES
  • Computational Intelligence Applied to Optimization of Effects Caused by Use of PBG Structures in Microstrip Antennas.

  • Advisor : JOSE PATROCINIO DA SILVA
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • JONATHAN PAULO PINHEIRO PEREIRA
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • MARINALDO PINHEIRO DE SOUSA NETO
  • Data: Dec 2, 2016


  • Show Abstract
  • The increasing demand for wireless technology in contemporary society requires the construction of integrated microwave circuits each time more sophisticated. In this sense, the planar microstrip antenna stands out because their small sizes and used in various applications, with emphasis on airplanes, satellites and mobile communication systems. In addition, recent researches shows the use of computing intelligence in telecommunications for analysis of new applications at microstrip antennas, as also the optimization of existing applications, searching for a better performance at the reception and / or signal transmission. In this context, this work has as objective get the radiation properties of microstrip antennas using the new models of Photonic Band Gap structures (PBG) based in meshes with periodic distributions and quasi-periodic printed on the substrate. Then, the prototypes of antennas developed were used to form a database for feeding the process of training an Artificial Neural Network (ANN), in order to obtain resonance frequency for second band of the antennas. Finally, it was optimized the procedure for obtaining the project frequency and PBG structure required for the antenna operating in a given frequency of resonance. According to the results, it can be concluded that it is possible to use an ANN in the optimization of a project of microstrip antenna with PBG substrate. The validation of the results provided by the ANN was based on building prototypes of the antennas, which showed good agreement between the simulated and measured values.

25
  • LUCÉLIA MARQUES LIMA DA ROCHA
  • Homogeneity and Pseudo-Homogeneity of interval T-Norms and interval-valued Atanassov's Intuicionistics T-norms

  • Advisor : BENJAMIN RENE CALLEJAS BEDREGAL
  • COMMITTEE MEMBERS :
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • EDUARDO SILVA PALMEIRA
  • FAGNER LEMOS DE SANTANA
  • GRAÇALIZ PEREIRA DIMURO
  • REGIVAN HUGO NUNES SANTIAGO
  • Data: Dec 5, 2016


  • Show Abstract
  • The set theory can't deal adequately with subjective linguistic terms, for example, "approximately '', "around '', "young '', among others. It was then, Lotfi A. Zadeh in 1965 suggested a generalization of set theory called fuzzy sets theory (FST), where in the passage membership to the non-memberhip was gradual and not abrupt, thus allowing to represent the uncertainty and inaccuracy of such linguistic terms.

    From the first moment it was clear that the FST was an exceptional tool to represent human knowledge. But Zadeh has shown that sometimes in decision-making processes, this knowledge is best represented by some generalizations or extensions of the fuzzy sets theory. Thus, there are several fuzzy extensions in literature, in which we can mention the interval-valued fuzzy sets theory (IVFST) where membership degrees are subintervals of [0,1], which was introduced in 1975
    independently by Zadeh and other researchers.

    Another extension of the FST was introduced by Krassimir Atanassov in 1983, which was called Atanassov's intuitionists fuzzy set theory (AIFST) that if characterized by considering both a membership degree as a non-membership degree. In 1989, Atanassov himself with G. Gargov proposed to consider intervals for both membership degrees as the non-membership. This latest extension is called  interval-valued Atanassov's intuitionistics fuzzy set theory (IVAIFST).

    Introduced by Menger in the context of the probabilistic metric space theory, a triangular norm or t-norm is a kind special associative function over a unit interval closed  [0,1]  and is used to define the intersection of fuzzy sets and has been used in various applications of FST such as rule-based fuzzy systems, decision making, fuzzy morphology, fuzzy formal languages, etc. This concept has also been generalized to different extensions of FST, however there are no records that have it has been made for IVAIFST. This thesis introduced the notion of t-standards for TCFIAIV.

    Thus, the Atanassov's intuitionists fuzzy sets are a natural generalization of fuzzy sets, and these are useful in applications in many situations of the day-to-day, such as decision making, digital image processing, among others. However, for these applications can not only use these sets, but we can also apply the concepts of homogeneity, of which play a key role in certain situations.

    Homogeneity is an analytical property that has theoretically been studied over time and in particular the homogeneity of
    t-norms has been studied exhaustively. In the literature there are several generalizations of the concept of homogeneity functions and among them there is the notion of pseudo-homogeneity introduced by Aifang Xie, Liu Yong Su and Huawen in order to generalize the quasi-homogeneous functions. In particular, pseudo-homogeneous t-norms were studied. In this sense, this thesis are presented new concepts regarding the homogeneity as well as the extension of the concept of the homogeneity and pseudo-homogeneity in  [0,1]  to interval homogeneity and interval pseudo-homogeneity, focusing mainly on the interval t-norms and interval-valued Atanassov's intuitionistics t-norms. We illustrate our results with examples of image processing and decision making.

26
  • CECÍLIO MARTINS DE SOUSA NETO
  • Power System Stabilizer Based on Wavelet Transform for Generation Systems. 

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ANTONIO MARCUS NOGUEIRA LIMA
  • FLAVIO BEZERRA COSTA
  • FRANCISCO DE ASSIS DOS SANTOS NEVES
  • JOSSANA MARIA DE SOUZA FERREIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Dec 9, 2016


  • Show Abstract
  • The power system stabilizers are used to suppress low-frequency electromechanical oscillations and improve the synchronous generator stability limits, while automatic voltage regulators control the terminal voltage of the synchronous generators.
    This thesis proposes a new methodology to design of an automatic voltage regulator and power system stabilizer for salient pole synchronous generator. The power system stabilizer employs a wavelet transform for extraction of the electromechanical oscillations in electrical power systems based on the scaling coefficient energy. The detection of the electrical oscillations effectuated by the wavelet coefficient energy and a control scheme generates the signal trigger to the power system stabilizer. A hybrid strategy composed of the integration of the sliding mode control system and the standard control implements the automatic voltage regulator. The effectiveness of the proposed power system stabilizer was evaluated experimentally through of a comparative study of a conventional power stabilizer system. On the other hand, the performance of the automatic voltage regulator was assessed and compared with a linear controller and two other hybrid control strategies. Furthermore, the performance of the wavelet transform was evaluated experimentally to detect electrical and electromechanical oscillations, in which the boundary wavelet transform presents the better performance.

2015
Dissertations
1
  • ELIEL POGGI DOS SANTOS
  • Projeto de absorvedores de micro-ondas integrados com superfícies seletivas em frequência

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • Data: Jan 29, 2015


  • Show Abstract
  • Com o rápido crescimento dos sistemas de comunicações sem fio, estudos envolvendo absorvedores de ondas eletromagnéticas tem despertado grande atenção pelos pesquisadores. Suas aplicações vão desde sistemas indoor até aplicações militares. Em paralelo a esse crescimento, os estudos crescentes emSuperfícies Seletivas em Frequência (FSS) permitem que suas propriedades de filtragem sejam aplicáveis em diversos sistemas como em antenas refletoras, em radomes passa-faixa e em absorvedores que será o foco desse trabalho.

    Esse trabalho tem como objetivo projetar absorvedores de micro-ondas usando FSS. A metodologia consiste basicamente em duas etapas: na primeira fase, uma análise teórica e numérica das estruturas envolvidas no processo de absorção e na segunda fase, a construção das estruturas. Para a análise será utilizado o Método dos Circuitos Equivalentes que prevêcaracterísticas detransmissão da estrutura para uma onda plana comincidêncianormal e requer recursos computacionais muito limitados quando comparados aos métodos de análise de onda completa e, portanto, é útil para predizer com rapidez o desempenho das estruturas. Também será usada a Matriz de espalhamento para cascatear a FSS condutiva e a FSS resistiva obtendo propriedades de absorção na faixa projetada.

    É apresentado o desenvolvimento matemático, pelo Método dos Circuitos Equivalentes, da modelagem de uma FSS com geometria do tipo dipolo cruzado e uma FSS resistiva como também o resultado cascateado entre as duas estruturas. Melhoramentos serão discutidos na conclusão como também as próximas etapas.

2
  • FABRÍCIO COSTA SILVA
  • Algoritmo eficiente para aquisição de sinais de GPS por software

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • FRANCISCO DAS CHAGAS MOTA
  • EDMAR CANDEIA GURJÃO
  • Data: Jan 29, 2015


  • Show Abstract
  • O NAVSTAR/GPS (NAVigation System with Timing And Ranging/Global Position-
    ing System), mais conhecido apenas por GPS, é um sistema de navegação baseado em
    satélites desenvolvido pelo departamento de defesa norte americano em meados de 1970.
    Criado inicialmente para fins militares, o GPS também foi adaptado para o uso civil.
    Este sistema é constituído basicamente por 24 satélites que orbitam a terra e enviam in-
    formações contínuas para os receptores dos usuários em qualquer lugar e sob qualquer
    condição climática. Para a utilização do GPS, o receptor precisa localizar os satélites
    visíveis para estabelecer a comunicação e, por fim, fazer a decodificação dos sinais e ex-
    tração das informações. A responsabilidade da etapa de aquisição é detectar os satélites
    visíveis, a frequência da portadora e o início do sinal de um determinado satélite. São
    necessários no mínimo quatro satélites para se fazer uma localização. Esse processo
    demanda bastante tempo de processamento e precisa ser implementado de forma efi-
    ciente. Várias técnicas são utilizadas atualmente, mas a maioria delas colocam em con-
    flito questões de projeto tais como, complexidade computacional, tempo de aquisição e
    recursos computacionais. Objetivando equilibrar essas questões conflitantes e melhorar o
    tempo de resposta do algoritmo de aquisição, foi desenvolvido um algoritmo que reduz a
    complexidade do processo de aquisição. Em comparação com algoritmo o convencional
    que demora em média 52 segundos para fazer a detecção de um satélite, o algoritmo
    desenvolvido consegue fazer a detecção em até 1.5 segundos.

3
  • ITALO AUGUSTO SOUZA DE ASSIS
  • UM ALGORITMO PARALELO EFICIENTE DE MIGRAÇÃO REVERSA NO TEMPO (RTM) 3D COM GRANULARIDADE FINA

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • DANIEL ALOISE
  • ROSANGELA CORREA MACIEL
  • REYNAM DA CRUZ PESTANA
  • Data: Jan 30, 2015


  • Show Abstract
  • O algoritmo de migração reversa no tempo (RTM) tem sido amplamente utilizado na
    indústria sísmica para gerar imagens do subsolo e, assim, reduzir os riscos de exploração.
    Seu uso em larga escala é devido a sua alta qualidade no imageamento do subsolo. O
    RTM é também conhecido pelo seu alto custo computacional. Por essa razão, técnicas de
    computação paralela têm sido utilizadas em suas implementações. Em geral, as aborda-
    gens paralelas para o RTM utilizam uma granularidade grossa, dividindo o processamento
    de um subconjunto de tiros sísmicos entre nós de sistemas distribuídos. A abordagem pa-
    ralela com granularidade grossa para o RTM tem se mostrado bastante eficiente uma vez
    que o processamento de cada tiro sísmico pode ser realizado de forma independente. To-
    davia, os nós dos sistemas distribuídos atuais são, em geral, equipamentos com diversos
    elementos de processamento sob uma arquitetura com memória compartilhada. Assim, o
    desempenho do algoritmo de RTM pode ser consideravelmente melhorado com a utiliza-
    ção de uma abordagem paralela com granularidade fina para o processamento designado
    a cada nó. Por essa razão, este trabalho apresenta um algoritmo paralelo eficiente de mi-
    gração reversa no tempo em 3D com granularidade fina utilizando o padrão OpenMP para
    memória compartilhada. Inicialmente foi desenvolvido um algoritmo de propagação da
    onda acústica 3D. Tal procedimento compõe grande parte do RTM. A partir desse pro-
    grama, foram analisados diferentes balanceamentos de carga a fim de minimizar possíveis
    perdas de desempenho paralelo. Em seguida, completou-se o RTM com a implementação
    da retropropagação e da condição de imagem. O algoritmo proposto foi testado com da-
    dos sintéticos representando algumas das possíveis estruturas do subsolo. Métricas como
    speedup e eficiência foram utilizadas para analisar seu desempenho paralelo. As seções
    migradas mostram que o algoritmo obteve um desempenho satisfatório na identificação
    das estruturas da subsuperfície. Já as análises de desempenho paralelo explicitam a esca-
    labilidade dos algoritmos alcançando um speedup de 22,47 para a propagação da onda e
    17,1 para o RTM, ambos com 24 threads.

4
  • MICHEL SANTANA DE DEUS
  • Amplificador Integrador com Ganho Programável por Largura de Pulso

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANTONIO AUGUSTO LISBOA DE SOUZA
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Jan 30, 2015


  • Show Abstract
  • Este trabalho trata da pesquisa e desenvolvimento de um Amplificador Integrador de Ganho Programável por Largura de Pulso. Propõe-se duas arquiteturas de amplificadores programáveis por pulsos, sendo uma discreta e outra baseada em capacitores chaveados. A partir de requisitos de operação definidos para o estudo, são definidos parâmetros e realizadas simulações para a validação das arquiteturas. Posteriormente, o software e o circuito são desenvolvidos e testados.

    É realizada a avaliação dos circuitos referentes às duas arquiteturas propostas, e a partir disso, seleciona-se uma arquitetura para que seja aperfeiçoada e permita o desenvolvimento de um circuito integrado em um trabalho futuro.

    É ainda proposto um método de autocalibração para a correção de possíveis desvios no ganho e no nível DC do amplificador.

5
  • ÍCARO BEZERRA QUEIROZ DE ARAÚJO
  • Sistema para a Detecção de Vazamentos em Instalações Prediais de Água Fria

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • FRANKLIN MARTINS PEREIRA PAMPLONA
  • Data: Jan 30, 2015


  • Show Abstract
  • Instalações prediais de água fria são partes fundamentais em qualquer modelo de habitação,
    sejam residências ou condomínios, desde as mais humildes até as mais esmeradas.
    Porém, tais sistemas estão sujeitos a falhas, que podem variar desde um vazamento em
    um aparelho, até falhas na estrutura dos reservatórios de água e sistema de distribuição.
    Estas falhas são responsáveis por grandes custos econômicos e ambientais. Visando reduzir
    estas perdas, este trabalho propõe o desenvolvimento de um sistema capaz de detectar
    a presença e identificar alguns tipos de vazamentos de água que venham a ocorrer. Para
    implementação e testes, no simulador desenvolvido, foi utilizado um modelo de consumo
    capaz de reproduzir o comportamento semelhante ao sistema real, assim como suas consequentes
    falhas. A detecção dos vazamentos é feita com base em um sistema semelhante
    a um sistema especialista que possui dois módulos de detecção, um passivo e outro ativo,
    os quais utilizam sensores e atuadores (válvulas) para fazerem a detecção. Para teste e
    implementação, foi desenvolvido um software capaz de acoplar o sistema simulador e o
    detector.

6
  • ANDERSON COSTA SILVA DOS SANTOS
  • Ferramenta para Análise de Ativos em Redes Industriais WirelessHART

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • ADRIAO DUARTE DORIA NETO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • EDUARDO PACIENCIA GODOY
  • Data: Mar 5, 2015


  • Show Abstract
  • Nos dias atuais a comunicação sem fio têm despertado interesse e está se tornando uma tendência nos ambientes industriais. Em parte esse interesse se deve às facilidades de implantações e manutenção desse tipo de rede, que dispensam projetos sofisticados e execução de obras de implantação de cabos, que em ambiente industriais muitas vezes têm custos proibitivos, além de permitir a criação de aplicações que não eram possíveis com as tecnologias legadas. Apesar dos benefícios diretos, desafios técnicos (confiabilidade, autonomia de recursos energéticos, interferência do ambiente) e culturais se apresentam como os principais pontos negativos para a implantação de redes industriais em larga escala na indústria. Nesta dissertação iremos abordar o problema da análise de ativos em redes industriais sem fio, dando especial ênfase ao padrão WirelessHart, que se apresenta como um dos mais promissores para solução de redes industriais sem fio. Neste trabalho apresenta-se um sistema para monitoramento de desempenho dos dispositivos em tempo real. Então de posse dessa ferramenta, pretende-se realizar diversas atividades de gestão de ativos, como prever a vida útil das baterias que alimentam os dispositivos para planejar atividades de manutenção preditiva de troca de baterias e reconfiguração do algoritmo de roteamento para preservar energia em nós críticos.

     

7
  • ERIDENES FERNANDES DE QUEIROZ
  • Modelagem do consumo de energia de redes de sensores sem fio usando SystemC-AMS e Stateflow.

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • ALISSON VASCONCELOS DE BRITO
  • Data: May 28, 2015


  • Show Abstract
  • Este trabalho tem como objetivo modelar o consumo de energia  em nós de uma Rede  de  Sensores  Sem  Fio  (RSSF).  Para  tanto,  foi  implementada  uma  máquina  de estados finita  utilizando a ferramenta  de modelagem e simulação SystemC-AMS com o objetivo  de  simular  o  consumo  de  energia  de  um  nó-sensor  em  um  ambiente  de comunicação  real.  A  mesma  máquina  de  estados  também  foi  implementada  na plataforma  Stateflow,  tal  implementação  tem  como  objetivo  comparar  os  resultados obtidos  na  simulação  com  SystemC-AMS.  Para  atingir  este  objetivo,  foi  realizada  a medição  da  corrente  de  dreno  utilizada  para  aquisição  de  dados  do  sensor  e  para  a comunicação  com  os  outros  nós  da  rede.  Além  de  simular  o  consumo  de  energia,  o ambiente de simulação  também utiliza um modelo de descarga  para fazer  a análise da situação energética atual da bateria. Esta análise resulta  em um gráfico de variação de tensão e estado de carga da bateria (SOC). Por fim,  é realizado um estudo de caso  do consumo  de  energia  em  RSSF  aplicado  a  aquicultura.  Tal  estudo  tem  como  objetivo analisar  o  modo  de  aquisição  e  comunicação  de  dados  da  rede.  Com  esta  análise  é possível  fazer ajustes  nos nó-sensores  de modo a reduzir o  consumo de energia  total  da rede.

8
  • EMANOEL RAIMUNDO QUEIROZ CHAVES JUNIOR
  • Topologia de Gerador de Distúrbios Elétricos Baseada em Conversores de Potência

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • JOSÉ ROBERTO BOFFINO DE ALMEIDA MONTEIRO
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • VALENTIN OBAC RODA
  • Data: Jun 19, 2015


  • Show Abstract
  • Equipamentos eletrônicos e de eletrônica de potência têm ficado extremamente susceptíveis
    a perturbações na rede elétrica. Distúrbios elétricos como afundamentos de
    tensão, interrupções e desequilíbrios de tensão podem causar sérios problemas para os
    consumidores e para as empresas de geração e transmissão de energia. Nos últimos anos,
    essas empresas de serviços elétricos vêm empregando técnicas e equipamentos de proteção
    para evitar a ocorrência distúrbios ou para amenizar os seus efeitos no sistema.
    Geradores de distúrbios são utilizados para analisar o comportamento de equipamentos
    elétricos e eletrônicos frentes às possíveis distúrbios elétricos. A análise dessas falhas
    permite o desenvolvimento equipamentos de proteção adequados. Neste trabalho, é proposto
    o desenvolvimento de um gerador de distúrbios baseado em conversores de potência
    que, aliado com uma estratégia de controle dos conversores, é capaz de gerar vários tipos
    de distúrbios simétricos como: afundamentos trifásico, elevações trifásicas e injeção de
    harmônicos. A estratégia de controle é baseada no controle linear discreto e no controle
    repetitivo. São detalhadas as etapas do projeto dos controladores e do filtro utilizado para
    a redução de harmônicos na saída. São apresentados os resultados obtidos com simulações
    computacionais e os resultados obtidos com ensaios do sistema implementado em
    laboratório.

9
  • PHILIPPI SEDIR GRILO DE MORAIS
  • iSalud: Uma Arquitetura para Publicação e Distribuição de Sistemas de Informação para o SUS 

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • RUMMENIGGE RUDSON DANTAS
  • Data: Jun 19, 2015


  • Show Abstract
  • O Programa Telessaúde Brasil Redes foi instituído pelo Ministério da Saúde, em 2007. Seu principal objetivo é apoiar os profissionais da Atenção Primária em Saúde (APS) com ofertas educacionais de qualificação, resultando em condições mais favoráveis na fixação do profissional em áreas remotas. A formulação e gestão dos serviços de telessaúde são realizadas por núcleos técnico-científicos, que são administrados por instituições públicas de ensino superior e responsáveis por prover ferramentas e serviços no contexto das regiões em que se encontram. Entretanto, os problemas gerados por essa descentralização é o desenvolvimento de várias ferramentas, com diferentes tipos de linguagem, arquitetura, sem qualquer regulamentação e integração das informações com o Ministério da Saúde. Com o objetivo de resolver o problema exposto, propõe-se a especificação, implementação e validação de um modelo arquitetural para o desenvolvimento e distribuição de ferramentas de software do Programa Telessaúde Brasil Redes. Essa arquitetura proposta permite que as ferramentas desenvolvidas nos núcleos sejam partilhados entre os demais núcleos, evitando, dessa forma, a utilização desnecessária de recursos.

10
  • DÊNIS KEUTON ALVES
  • Estimação de Potência em Tempo Real Utilizando a Transformada Wavelet

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FLAVIO BEZERRA COSTA
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • GEORGE ROSSANY SOARES DE LIRA
  • Data: Jun 19, 2015


  • Show Abstract
  • A monitoração das grandezas elétricas em sistemas elétricos de potência tem como objetivo promover a confiabilidade, bem como a qualidade da energia elétrica distribuída. Diante disso, propõe-se nessa dissertação um estudo sobre uma nova teoria de potência baseada na transformada wavelet para estimação em tempo real dos valores RMS da tensão e corrente e alguns valores de potências, tais como: potência ativa, potência reativa, potência aparente e fator de potência. A estimação adequada dos valores RMS e das potências são importante para diversas aplicações, como por exemplo: projetos e análise de sistemas de energia, dispositivos de compensação para melhorar a qualidade da energia elétrica e instrumentos de medição de energia. Os resultados de simulação e experimentais obtidos pelo método proposto baseado na transformada wavelet discreta redundante
    foram comparados por meio do padrão IEEE 1459-2010 e por um osciloscópio comercial, respectivamente, apresentando resultados equivalentes. O método proposto apresentou bom desempenho para wavelets mães curtas, o que torna viável para aplicações em tempo real.

11
  • SÂMARA DE CAVALCANTE PAIVA
  • Proteção em Sistemas Elétricos com Geração Distribuída Utilizando a Transformada Wavelet

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Jun 22, 2015


  • Show Abstract
  • Um sistema elétrico de potência típico é caracterizado pela centralização da geração
    de energia por questões de economia, maior segurança, confiabilidade e qualidade do suprimento
    de energia. Entretanto, com a reestruturação do sistema elétrico, esta topologia
    vem modificando-se através da operação de geradores em paralelo com o sistema de distribuição.
    Essa nova alternativa de topologia é conhecida como geração distribuída. A
    geração distribuída proporciona diversos benefícios por localizar-se próximo aos centros
    de consumo. Além disso, permite o atendimento da demanda crescente de forma rápida
    devido ao seu processo de implantação. Com isso, a inserção de geradores distribuídos,
    especialmente provenientes de fontes renováveis, no sistema brasileiro tende a se tornar a
    cada ano mais comum. Entretanto, esta nova configuração do sistema traz problemas de
    controle, operação e proteção. Um dos principais problemas da geração distribuída nos
    sistemas de proteção é a formação de ilhas energizadas (ilhamento). Um sistema ilhado
    traz riscos de segurança as pessoas, ao gerador distribuído e a rede de energia elétrica.
    Existem diversas técnicas de proteção contra a formação destas ilhas energizadas. Dentre estas técnicas, as técnicas passivas destacam-se neste trabalho devido seu custo de implementação e sua simplicidade. Técnicas passivas, utilizam medidas de tensão, corrente e frequência para detectar situações de ilhamentos. Propõe-se neste trabalho o desenvolvimento de um esquema de
    proteção baseado na transformada wavelet com as funções de proteção de sobrecorrente,
    sub/sobretensões e informações dos transitórios de falta para rápida detecção e identificação
    de situações de ilhamentos. Os resultados foram comparados com os métodos de
    proteção convencionais de sobrecorrente e sub/sobretensão com o objetivo de demonstrar
    o melhor desempenho do método proposto em relação aos convencionais.

12
  • RENATA LEIROS ROMANO
  • Controle em Modo Dual Adaptativo Robusto Aplicado a um Sistema de Geração de Energia Elétrica

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • CAIO DORNELES CUNHA
  • JOSE ALVARO DE PAIVA
  • Data: Jun 23, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • Os geradores síncronos, predominantes nos sistemas de geração de energia elétrica,
    necessitam de valores de tensão e frequência constantes para a obtenção de uma boa
    qualidade da energia gerada. Porém, para situações em que esses sistemas sofrem grandes
    variações de carga, há dificuldade de que sejam mantidos os valores nominais nas saídas do
    gerador devido às incertezas paramétricas, não linearidades e alto grau de
    acoplamento entre as variáveis. Propõe-se, então, a aplicação do
    Controlador em Modo Dual Adaptativo Robusto (DMARC) para o controle do fluxo de
    campo, em substituição aos tradicionais controladores PIs. O DMARC estabelece uma
    ligação entre um controlador adaptativo por modelo de referência (MRAC) e um
    controlador adaptativo por modelo de referência e estrutura variável (VS-MRAC),
    incorporando as vantagens de desempenho transitório do controlador VS-MRAC com as
    propriedades de regime permanente do controlador MRAC convencional. São feitas
    análises através de simulações como forma de verificar o funcionamento do controlador proposto, bem como
    compará-lo com o sistema atualmente em uso.
13
  • HEITOR MEDEIROS FLORENCIO
  • Ferramenta de Avaliação e Inferência de Parâmetros de Redes Industriais Sem Fio

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DENNIS BRANDAO
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jul 20, 2015


  • Show Abstract
  •  

    As redes de sensores sem fio (RSSF) estão gradativamente ganhando espaço no ambiente industrial devido à possibilidade de conectar pontos de informação que eram inacessíveis com as redes cabeadas. Contudo, existem vários desafios na implantação e aceitação dessa tecnologia no meio industrial, sendo um deles a garantia de disponibilidade da informação, a qual pode ser influenciada por vários parâmetros, como a estabilidade dos caminhos de dados e o consumo de energia do instrumento de campo. Nesse sentido, neste trabalho foi desenvolvido uma ferramenta de avaliação e inferência de parâmetros de redes industriais sem fio baseadas nos protocolos WirelessHART e ISA 100.11a. A ferramenta disponibiliza funcionalidades de avaliação quantitativa, como quantitativo de pacotes, qualitativa e por inferência durante um determinado tempo de execução da rede. As avaliações quantitativa e qualitativa são baseadas nas próprias definições dos parâmetros, como a definição de estabilidade, ou em ferramentas da estatística descritiva, como médias e diagramas de caixa. Já na avaliação por inferência é utilizada a técnica de rede neural artificial para estimar os parâmetros, como vida útil da bateria. Por fim, são apresentados os resultados do uso da ferramenta em diferentes cenários de redes, redes em estrela e em malha, assim atestando a importância do uso de ferramentas de avaliação do funcionamento dessas redes para apoiar possíveis adequações ou manutenções do sistema.
14
  • JORGE EIDER FLORENTINO DA SILVA
  • Uma Ferramenta para Diagnóstico em Válvulas Industriais Baseada em Testes Padrões ISA

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • BRUNO SIELLY JALES COSTA
  • Data: Jul 27, 2015


  • Show Abstract
  • Válvulas posicionadoras são um dos mais importantes instrumentos de atuação na automação industrial. Como esses instrumentos possuem partes mecânicas móveis, não raro surgem vários problemas como folgas e atrito seco, conhecido como agarramento. Sendo que esses problemas acabam por prejudicar o desempenho de malhas de controle que possuem tais tipos de instrumento, inclusive podendo levar o sistema a instabilidade, em alguns caos. Assim, avaliar adequadamente a saúde de válvulas é uma atividade muito importante em manutenção da operação de processos industriais.  Então, diante desta relevância, neste trabalho é proposto o projeto e a implementação de um software de avaliação de válvulas posicionadoras industriais, de acordo com as especificações ANSI/ISA. Desta forma, a avaliação é gerada a partir da execução de testes padronizados, com a finalidade de se detectar problemas como folga e agarramento. Com esse objetivo, o software é capaz de gerar sinais de entrada específicos para cada teste levando em consideração parâmetros definidos pelo usuário, permitindo a flexibilização e a execução dos testes em diferentes tipos e tamanhos de válvulas. Através da análise desses dados será realizada a extração dos parâmetros que refletem o estado atual da válvula sob análise. A partir desses resultados pode-se monitorar e acompanhar o estado de saúde dos instrumentos em estudo e fazer a devida manutenção em tempo hábil, evitando-se dessa forma a descontinuidade da operação ou parada total do sistema e gastos desnecessários.

15
  • SANDRO BRUNO DO NASCIMENTO LOPES
  • Análise do Comportamento de Técnicas de Correspondência Binocular para Imagens em Alta Definição.

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • ROSIERY DA SILVA MAIA
  • Data: Jul 30, 2015


  • Show Abstract
  • Neste trabalho, verificamos o comportamento de alguns algoritmos usualmente disponíveis na literatura de correspondência estéreo com imagens full HD (1920x1080 pixels) e estabelecemos, dentro do dilema precisão versus tempo de execução, quais aplicações estes mé-todos podem ser melhor aproveitadas. As imagens são obtidas por um um sistema composto por uma filmadora estéreo acoplada a um computador por meio de uma aplaca de captura. A biblioteca OpenCV é utilizada para as operações de visão computacional e processamento de imagens envolvida, cujo projeto possui artigo publicado em congresso. Os algoritmos analisados são um método global de busca por correspondência em blocos com soma do valor absoluto das diferenças (SAD), uma técnica global baseada em corte de grafos de energia, frequentemente conhecida como graph cuts, e uma uma técnica de correspondência dita semi-global. Dentre os critérios estabelecidos estão o tempo de processamento, o consumo de memória e o número de pixels mal-correspondidos. Como contribuição do traballho, podemos usar as análises realizadas para indicar os melhores algoritmos a serem usados em diversos casos, principálmente usando os critérios de tempo real x precisão.

16
  • THIAGO FERREIRA PAULO
  • Controle Adaptativo com Desacoplamento Aplicado à um Sistema de Tanques Acoplados MIMO

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • GILBERT AZEVEDO DA SILVA
  • Data: Jul 31, 2015


  • Show Abstract
  • O controle de sistemas MIMO (Multiple Input Multiple Output) é muitas vezes realizado por várias malhas de controladores clássicos que operam com restrições e apresentam baixo desempenho. Técnicas de controle adaptativo são uma alternativa interessante para aumentar o rendimento desses sistemas, como por exemplo os controladores MRAC (Model Reference Adaptive Control), que quando bem projetados, permitem que a dinâmica da planta seja escolhida de maneira a seguir um modelo de referência. O presente trabalho apresenta uma estratégia de desacoplamento para um sistema MIMO de três tanques acoplados e o projeto de um controlador MRAC para o mesmo.

17
  • BOANERGES VICTOR SOARES DE ARAÚJO
  • Estudo de Famílias Wavelets para Aplicação em Método de Análise Empregado em DOAS

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • ERICO CADINELI BRAZ
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • Data: Aug 17, 2015


  • Show Abstract
  • Gases-traço são importantes para nosso ambiente, mesmo se manifestando apenas em ‘traços’, mas suas concentrações devem ser monitoradas, para que quaisquer intervenções necessárias sejam tomadas a tempo. Condições apropriadas para nossas vidas residem dentro de limites inferiores e superiores destes gases, por isso seu monitoramento é essencial hoje em dia e diversas técnicas podem ser usadas para este fim. Uma delas é a espectroscopia de absorção óptica diferencial (DOAS), que consiste de uma regressão - o método clássico usa mínimos quadrados - para determinar a concentração dos gases-traço. Para melhorar os resultados, diversos estudos buscaram abordagens alternativas. Alguns tentaram pré-processar o sinal, através de uma remoção de ruído, e.g., usando transformada wavelet discreta (DWT). Este trabalho apresenta um estudo semi-empírico para encontrar a DWT com o melhor desempenho para remoção de ruído. Dentre diversas famílias conhecidas, buscou-se aquelas cuja remoção de ruído foram melhor, preservando características principais do sinal original, então com a redução do ruído, o resíduo após a regressão também diminui. A análise leva em conta o nível de decomposição wavelet, o limiar aplicado nos coeficientes de detalhe e como aplicá-los - limiariazação abrupta ou suave. Os sinais usados provêm de um banco de dados aberto e online com sinais característicos de gases-traço usualmente estudados.

18
  • EDUARDO NOGUEIRA CUNHA
  • Modelagem, Simulação e Controle de Sistemas de Abastecimento de Água: Um Estudo de Caso do Campus da Universidade Federal do Rio Grande do Norte

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRES ORTIZ SALAZAR
  • OSCAR GABRIEL FILHO
  • Data: Oct 15, 2015


  • Show Abstract
  • Os sistemas de abastecimento de água são sistemas complexos e de difícil operação, possuem diversas configurações no que diz respeito aos elementos ativos e passivos contidos no sistema. O seu controle e monitoramento é de suma importância para a operação racional do sistema visando sempre atender de forma satisfatória à população minimizando ao máximo as perdas hídricas e tornando o sistema mais eficiente em termos energéticos. Os sistemas de abastecimento constituem-se em geral de sistemas críticos, onde não há possibilidades de tempo de parada para testes e simulações, assim, para realizar o controle de forma adequada é necessário um modelo que represente o sistema de forma satisfatória, onde seja possível simular e testar as mais diversas situações às quais o sistema é normalmente submetido no dia-a-dia. Neste trabalho é apresentado o modelo matemático do sistema de abastecimento de água (SAA) da Universidade Federal do Rio Grande do Norte (UFRN) contemplando todos
    os elementos presentes em seu sistema. Três controladores são implementados em nível de simulação e tem seus desempenhos comparados: servossistema tipo 1, o controlador preditivo linear e um controlador preditivo não-linear. O objetivo é mostrar que  podemos utilizar o modelo do sistema para testes e simulação de condições de  funcionamento e sintonia do controlador para obter o melhor desempenho do SAA.

19
  • DANIELE MONTENEGRO DA SILVA BARROS
  • Teleconsultoria Off-line: uma arquitetura distribuída e compartilhada para sistemas heterogêneos

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • BRUNO GOMES DE ARAUJO
  • KARILANY DANTAS COUTINHO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Nov 6, 2015


  • Show Abstract
  • O Programa Telessaúde Brasil Redes, criado em 2007 com o objetivo de fortalecer a Atenção Básica e o Sistema Único de Saúde (SUS),  utiliza as tecnologias de informação e comunicação para atividades à distância relacionadas à saúde, possibilitando a interação entre profissionais de saúde e/ou seus pacientes, promovendo a qualificação das Equipes de Saúde da Família (ESF). O Programa é embasado por lei, que determina uma série de tecnologias, protocolos e processos aos quais norteiam o trabalho dos Núcleos de Telessaúde na oferta dos serviços para a população. Entre esses serviços está a teleconsultoria, que é consulta registrada e realizada entre trabalhadores, profissionais e gestores da área de saúde, por meio de instrumentos de telecomunicação bidirecional, com o fim de esclarecer dúvidas sobre procedimentos clínicos, ações de saúde e questões relativas ao processo de trabalho. Com a expansão do Programa em 2011 foi possivel detectar desafios e problemas que abrangem praticamente todos os Núcleos, em escalas diferentes para cada região. Entre esses problemas pode-se listar a heterogeineidade das plataformas, principalmente de teleconsultoria, e a baixa cobertura de internet dos municipios, principalmente no interior do Brasil. Nessa perspectiva, o objetivo deste trabalho é propor uma arquitetura distribuída, que utilize computação móvel, para automatizar o processo de submissão e resposta de uma teleconsultoria. Essa arquitetura irá funcionar de forma Off-line e possibilitará que os dados trafeguem pela internet de forma compressada, para diminuir a necessidade de altas taxas de transmissão de dados. Outro ponto da arquitetura, é a possibilidade de ser utilizada por vários Núcleos de Telessaúde, através de um serviço externo, que possa ser acoplado através de uma interface a outras plataforma de teleconsultoria.

20
  • EDSON JACKSON DE MEDEIROS NETO
  • Análise de desempenho de algoritmos de compressão de dados com perda para aplicações industriais

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • FABIO SOARES DE LIMA
  • Data: Nov 9, 2015


  • Show Abstract
  • O grande volume de dados gerados como resultado da supervisão de processos de automação na indústria gerou como consequência um vasto espaço de armazenamento em disco, assim como dificuldade na transmissão destes dados por links de telecomunicações. Os algoritmos de compressão com perda de dados surgiram na década de 90 com intuito de solucionar estes problemas, passando a serem utilizados em sistemas de supervisão industrial para a compressão de dados em tempo real. Para isso estes foram projetados para eliminar informações redundantes e indesejadas de forma simples e eficiente. No entanto, os parâmetros destes algoritmos necessitam de serem configurados para cada variável de processo, tornando inviável a configuração manual em caso de sistemas que supervisionam milhares de variáveis. Nesse contexto este trabalho propõe o algoritmo Adaptive Swinging Door Trending, que consiste numa adaptação do Swinging Door Trending, em que seus principais parâmetros são ajustados dinamicamente através da análise de tendências do sinal. Propõe-se também uma análise comparativa de desempenho dos algoritmos de compressão com perda de dados aplicados sobre variáveis de processo de séries temporais e cartas dinamométricas de fundo de poço. Os algoritmos abordados para efeito comparativos foram os lineares por partes e os de transformadas.

21
  • DANIELLE BRITO MARQUES
  • METODOLOGIA PARA ANALISE DA DEPENDABILIDADE DE SMART GRIDS

  • Advisor : IVANOVITCH MEDEIROS DANTAS DA SILVA
  • COMMITTEE MEMBERS :
  • ANDRE MORAIS GURGEL
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARIA DA GUIA DA SILVA
  • Data: Dec 4, 2015


  • Show Abstract
  •  Redes inteligentes representam um novo conceito de distribuição de energia elétrica, que são o futuro dos sistemas atuais. Essas redes têm sido introduzidas com o objetivo de aumentar a confiabilidade dos sistemas, prover alternativas para o suprimento de energia e reduzir custos. O aumento da complexidade das redes de energia, a crescente demanda e a introdução de fontes renováveis de geração de energia, requerem uma integração e operação de todos os componentes do sistema, a fim de garantir altos índices de confiabilidade e disponibilidade (dependabilidade).  A sistematização das redes inteligentes a partir do formalismo matemático de Árvores de Falhas possibilita a analise quantitativa de tais índices. Nesse trabalho é proposto uma metodologia para análise da dependabilidade de redes inteligentes no contexto de distribuição de energia elétrica. Um estudo de caso é proposto para validar a proposta. A partir da metodologia é possível estimar ainda na fase de projeto a confiabilidade, disponibilidade e identificar os pontos críticos da rede através das distribuições estocásticas das taxas de falhas e reparos dos componentes.

22
  • RAMON AUGUSTO SOUSA LINS
  • SISTEMA INTELIGENTE PARA O PROCESSAMENTO  DE IMAGENS DIGITAIS INTRABUCAIS OCLUSAIS

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • HELIANA BEZERRA SOARES
  • MARCO ANTONIO GARCIA DE CARVALHO
  • Data: Dec 4, 2015


  • Show Abstract
  • Neste trabalho é proposto o desenvolvimento de um sistema inteligente capaz de segmentar, contar e classificar individualmente dentes a partir de imagens fotográficas digitais intraorais oclusais.O sistema proposto faz uso combinado das técnicas de aprendizagem de máquina no caso a máquina  de vetor  de suporte e processamento digital de imagens. Primeiramente é feita uma segmentação baseada nas cores dos dentes e não dentes presentes na imagem através do uso de máquina de vetores de suporte. A partir da identificação das regiões de interesse, dentes e não dentes, os dados são representados de modo que a contagem, detecção de fronteiras e  classificação dos dentes possa ser feita. Para contagem e detecção de fronteiras são utilizadas técnicas baseadas em operadores morfológicos, erosão e transformada watershed, respectivamente. A classificação quanto aos tipos de dentes é baseada na utilização dos descritores de posição e forma, sendo esse último definido por descritores de Fourier. O sistema portanto é capaz de realizar a segmentação, a contagem e a classificação de dentes presentes nas imagens.

23
  • ÁTILA VARELA FERREIRA MEDEIROS DE OLIVEIRA
  • Estratégia de Navegação com Planejamento Dinâmico e Algoritmo Genético Aplicada a Robôs Móveis Terrestres

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Dec 7, 2015


  • Show Abstract
  • Este trabalho propõe uma nova estratégia de navegação autônoma assistida por algoritmo genético com planejamento dinâmico para robôs móveis terrestres, chamada DPNA-GA (Dynamic Planning Navigation Algorithm optimized with Genetic Algorithm). A estratégia foi aplicada em ambientes – tanto estáticos, quanto dinâmicos – nos quais a localização e o formato dos obstáculos não são previamente conhecidos. A cada evento de deslocamento, uma nova rota é planejada através de um algoritmo que minimiza a distância entre o robô e o objetivo e maximiza a distância em relação aos obstáculos. Utilizando um sensor de localização espacial e um conjunto de sensores de distância, a estratégia de navegação proposta foi capaz de planejar dinamicamente percursos ótimos livres de colisão. Simulações realizadas em diferentes ambientes demostraram que a técnica fornece um alto grau de flexibilidade e robustez. Para isso, foram aplicadas diversas variações de parâmetros genéticos, tais como: taxa de cruzamento, tamanho da população, dentre outros. Finalmente, os resultados das simulações demonstram satisfatoriamente a eficácia e robustez da técnica DPNA-GA, validando-a para aplicações reais em robôs móveis terrestres.

24
  • JONAS DAMASCENO BATISTA DE ARAÚJO
  • Protótipo de Rastreador Solar de um eixo baseado em microcontrolador

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • ALEXANDRE CUNHA OLIVEIRA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • VALENTIN OBAC RODA
  • Data: Dec 9, 2015


  • Show Abstract
  • O aumento da eficiência de sistemas foto-voltaicos tem sido alvo de diversos estudos nos últimos anos. Uma das formas possíveis de aumentar a potência extraída por um painel foto-voltaico é o rastreamento solar, realizando a sua movimentação de modo a seguir a trajetória do sol. Esta movimentação exige que o motor elétrico empregado possua torque suficiente e baixa velocidade, garantindo a precisão do rastreamento. Com o uso de inversores tipo fonte de tensão e de dispositivos que gerem a lógica de chaveamento adequada é possível obter o torque e a velocidade necessários para o funcionamento do sistema. Este trabalho descreve a implementação de um sistema de controle de posição a ser aplicado no rastreador solar construído no Laboratório de Eletrônica de Potência e Energias Renováveis, situado na UFRN. A variação da velocidade do motor é realizada através de um inversor tipo fonte de tensão cujo comando PWM para acionamento das chaves será gerado por um dispositivo microcontrolador dedicado. O sensor utilizado para medição da inclinação do painel é um sensor de estado sólido do tipo acelerômetro interfaceado ao microcontrolador. A posição solar é também calculada pelo microcontrolador à partir das coordenadas geográficas do ponto de instalação, e da data e hora locais obtidas a partir de um dispositivo RTC (Real-Time Clock). Um protótipo de rastreador solar polar de um eixo, movimentado por um motor CC, foi montado para atestar o funcionamento do sensor e verificar se o rastreamento é realizado de forma eficiente.

25
  • TIAGO ALVES DE ALMEIDA
  • Uma Técnica de Linearização por Realimentação para Compensação de Agarramento em Válvulas de Controle Pneumáticas

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • VICENTE DELGADO MOREIRA
  • Data: Dec 17, 2015


  • Show Abstract
  • Agarramento em válvulas é um problema muito comum em malhas de controle e geralmente é a principal causa do mau desempenho de sistemas industriais. Os efeitos desta não linearidade mais comumente observados são oscilações nas variáveis de processo. Para contornar os efeitos indesejáveis, compensadores de atrito têm sido propostos, com o objetivo de reduzir a variabilidade na saída. Neste trabalho é analisada a compensação do atrito em válvulas de controle pneumáticas por meio de uma técnica de linearização por realimentação. O modelo da válvula utilizado inclui tanto zona morta quanto salto. Resultados de simulação mostram que o uso desse modelo mais completo resulta em controladores com desempenho superior. O método é também comparado por meio de simulações com o método conhecido como Reforço Constante (CR), bastante utilizado neste problema.

Thesis
1
  • ROMULO ALVES DE OLIVEIRA
  • Especificação e Implementação de um Algoritmo Genético para Otimização de
    Projetos de Iluminação Pública
  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • JOSE LUIZ DA SILVA JUNIOR
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARIA EMILIA DE LIMA TOSTES
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Jan 27, 2015


  • Show Abstract
  • Atualmente os projetos de Iluminação Pública (IP), ou seja, ruas, avenidas, praças, estacionamentos e similares são realizados com a utilização de softwares comerciais ou livres, em geral, fornecidos por fabricantes ou grupos de fabricantes de produtos de iluminação, aplicando o Método Ponto a Ponto para o cálculo dos níveis de iluminação. Outros pontos em comum são: a falta de preocupação na redução dos custos dos projetos e a dificuldade em modificar as estruturas utilizadas, tais como: localização e altura dos postes e luminárias, ângulo de inclinação das luminárias, quantidade de luminárias por poste, entre outros. Qualquer alteração nas estruturas terá que ser feita manualmente, geralmente em um ambiente CAD, para depois obter os novos resultados e comparar com os anteriores. Para auxiliar nessa tarefa, é proposta aqui a utilização da Metaheurística Colônia de Formigas, onde os parâmetros e localização das estruturas passam a ser definidos automaticamente, de forma a atender os níveis de iluminação estabelecidos nas normas técnicas, além de otimizar o custo de material por unidade de área.

2
  • JOSE IDIFRANSE AGUIAR TRINDADE
  • ESTUDO DA VARIAÇÃO DA PERIODICIDADE E DO ACOPLAMENTO ENTRE FSS COM ELEMENTOS FRACTAIS E HELICOIDAIS EM ESTRUTURAS DE MULTICAMADAS


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • HERTZ WILTON DE CASTRO LINS
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • Data: Jan 30, 2015


  • Show Abstract
  • Este trabalho tem como objetivo investigar o comportamento de elementos fractais e elementos helicoidais em estruturas planares de microfita. Em particular, as superfícies seletivas de frequência (FSS) tiveram seus elementos convencionais alterados para formatos fractais e para o formato helicoidal. O substrato dielétrico usado é de fibra de vidro (FR-4) e tem espessura de 1,5 mm, permissividade elétrica relativa de 4,4 e tangente de perdas igual a 0,02. Para as FSS, adotou-se a geometria fractal pentagonal de Dürer e a geometria helicoidal. Para efetuar as medições, foram utilizadas duas antenas cornetas em visada direta, conectadas por cabo coaxial a um analisador de redes vetorial. Alguns protótipos foram selecionados para fabricação e medição. A partir dos resultados preliminares obtidos, objetivou-se encontrar aplicações práticas para as estruturas a partir do cascateamento entre elas. Para as FSSs com elementos fractais de Dürer, observou-se um comportamento multibanda proporcionado pela geometria fractal, ao mesmo tempo em que a largura de banda se tornou estreita na medida em que o nível de iteração fractal aumentou, tornando-a uma estrutura mais seletiva em frequência, com um maior fator de qualidade. Uma análise paramétrica possibilitou a análise da influência da variação da camada de ar entre elas. As estruturas fractais pentagonais foram consideradas e cascateadas. O cascateamento entre determinadas estruturas pentagonais apresentou um comportamento tri-band para determinados valores da camada de ar entre elas, com aplicações na banda licenciada 2,5 GHz (2,3 ~ 2,7 GHz), e 3,5 GHz (3,3 ~ 3,8 GHz). Para as FSSs com elementos helicoidais, seis estruturas foram consideradas. A partir de resultados preliminares obtidos com a análise isolada das estruturas, o cascateamento entre elas proporcionou o aumento da largura de banda, na medida em que a espessura da camada de ar aumenta. Com a finalidade de encontrar aplicações práticas para as estruturas helicoidais cascateadas, as estruturas propostas foram cascateadas e as mesmas encontraram aplicações na banda-X (8,0 ~ 12,0 GHz), e na banda não licenciada que compreende a faixa de 5,25 a 5,85 GHz. Na caracterização numérica e experimental das estruturas abordadas, utilizou-se, respectivamente, o software comercial Ansoft Designere um analisador de redes vetorial, modelo N5230A da Agilent.

3
  • ALAN PAULO OLIVEIRA DA SILVA
  •  Modelo Comportamental do Capacitor Ferroelétrico como Unidade Básica de Neurônios Artificiais e sua Implementação em FPGA

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • DANNIEL CAVALCANTE LOPES
  • HELIANA BEZERRA SOARES
  • MARCELO AUGUSTO COSTA FERNANDES
  • VICENTE IDALBERTO BECERRA SABLON
  • Data: Jan 30, 2015


  • Show Abstract
  • As Redes Neurais Artificiais (ANNs) tem sido amplamente utilizadas no campo da inteligência artificial. As ANNs tem sua inspiração básica no sistema nervoso biológico e são máquinas computacionais com um alto grau de paralelismo normalmente compostas por redes paralelas de elementos não linears, os quais são chamados de neurônios artificiais. Os neurônios artificiais são organizados em camadas e são interligados através de pesos sinápticos de acordo com a arquitetura proposta pelo modelo da rede neural artificial. Muitas pesquisas tem sido realizadas envolvendo as ANNs, inclusive a implementação de neurônios artificiais em placas de hardware e a construção de sistemas inteligentes embarcados.

    Este trabalho propõe a implementação da lógica booleana através de neurônios artificiais com Capacitores Ferroelétricos (FeCapacitor) como sua unidade básica em plataforma de hardware reconfigurável. Será implementado em hardware o modelo do neurônio artificial Perceptron utilizando o FeCapacitor. Além disso, o modelo do Spiking Neuron, utilizando o FeCapacitor, será também implementado, já que ele tem a capacidade de implementar todas as portas lógicas com um único neurônio, inclusive a porta XOR. Os modelos serão embarcados em uma placa de hardware Field Programmable Gate Array (FPGA). As implementações serão realizadas através de modelos em Simulink e a sintetização dos mesmos será feita com o auxílio do software DSP Builder, da Altera Corporation. Através do DSP Builder também serão gerados os códigos VHDL de cada modelo implementado.

4
  • CARLOS GOMES DE MOURA
  • Uso de Metamaterial em Antenas de Microfita com Supercondutor


  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • HUMBERTO DIONISIO DE ANDRADE
  • JOSE PATROCINIO DA SILVA
  • MARINALDO PINHEIRO DE SOUSA NETO
  • RONALDO DE ANDRADE MARTINS
  • Data: Feb 6, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • Na sua estrutura mais simples a antena de microfita é composta de um elemento metálico (patch) depositado num substrato que, por sua vez, está sobre um plano de terra. O patch, ou elemento ressoador, pode ter várias geometrias tais como: quadrada, retangular, circular, elíptica, triangular ou qualquer outra configuração, de acordo com a característica desejada.

    Os metamateriais tem atraído uma grande atenção nas ultimas décadas, em decorrência de suas propriedades eletromagnéticas não serem encontradas na natureza. Desde que os metamateriais passaram a ser sintetizados através da inserção de inclusões artificialmente fabricadas num meio homogêneo especificado, facilitou ao pesquisador uma larga coleção de parâmetros independentes, como, por exemplo, as propriedades eletromagnéticas do material. Foram realizadas uma investigação das propriedades dos Ressoadores em anel e dos metamateriais.

    Foi apresentado um estudo das principais teorias que explicam com clareza a supercondutividade. As teorias BCS, Equações de London e modelo dos Dois Fluidos são as teorias que dão suporte a aplicação dos supercondutores nas antenas de microfita.

    Assim, esta Tese de Doutorado apresenta uma análise teórica, numérico-computacional e experimental, utilizando o formalismo de onda completa, através da aplicação do método da Linha de Transmissão Transversa – LTT, aplicado no Domínio da Transformada de Fourier (FTD). O LTT é um método de onda completa, que tem como regra a obtenção dos campos eletromagnéticos em termos dos componentes transversais à estrutura. A inclusão do patch supercondutor é feita utilizando-se a condição de contorno complexa resistiva. São obtidos resultados da freqüência de ressonância em função dos parâmetros da antena. Para validação das análises foram elaborados programas computacionais na linguagem Fortran, simulações no software comercial Ansoft HFSS®, sendo as curvas traçadas no HFSS e no software Matlab, além de se comparar o patch convencional com o supercondutor e depois se comparar um substrato metamaterial com um convencional, juntando o substrato com o patch, verificando o que melhora em ambos os quesitos, demonstrando a utilização prática destas estruturas em antenas fabricadas em laboratório.

5
  • GUTEMBERGUE SOARES DA SILVA
  • Contribuições ao estudo de modelagem de equações estruturais  na avalição da satisfação do cliente de serviços de comunicações móveis.

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANDRE PEDRO FERNANDES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE ALFREDO FERREIRA COSTA
  • RONALDO DE ANDRADE MARTINS
  • TEOFILO CAMARA MATTOZO
  • Data: Feb 26, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • No mercado de telecomunicações as transformações tecnológicas das últimas décadas aliaram-se a um cenário formado por empresas de alta tecnologia que caracterizam o setor de comunicações móveis pessoais em todo mundo. Neste contexto, as empresas deste setor preocupam-se cada vez mais com a competitividade, oferta de serviços, área de atendimento, demanda reprimida e a lealdade do cliente. Estudos de comportamento do consumidor pesquisam a satisfação e lealdade de clientes como fatores básicos para relações bem sucedidas e duradouras com as empresas. A complexidade das relações entre variáveis na avaliação da satisfação do cliente em comunicações móveis pode ser adequadamente pesquisada com a utilização de métodos estatísticos multivariados. Essa tese analisou as relações causais envolvendo os antecedentes e consequentes associados à satisfação do cliente, no segmento de comunicações móveis, bem como desenvolveu e validou um modelo comportamental do cliente no uso deste serviço, buscando explicar as relações entre os construtos envolvidos: satisfação, qualidade dos serviços, valor percebido, imagem da marca, lealdade e reclamação. Foi estabelecida uma ampla base teórica para avaliar a importância estratégica do modelo que relaciona a influência na satisfação do serviço com as percepções dos clientes e avaliada a precisão deste modelo, por meio de uma análise comparativa a utilização de três métodos de estimação dos seus parâmetros, MLE, GLS, e ULS, com o emprego de modelagem de equações estruturais. Foram feitas aplicações em análises de dados, sendo testada e avaliada empiricamente, a influência do gênero na satisfação do cliente deste setor, além de uma segmentação de mercado utilizando mapas auto-organizáveis e a correspondente validação deste processo, com modelagem de equações estruturais.Os resultados do estudo empírico produziram uma boa qualidade de ajustamento para o modelo teórico proposto, com evidências do estabelecimento de uma adequada capacidade explicativa e preditiva, destacando-se a relevância da relação causal entre a satisfação e lealdade, em consonância com diversos estudos realizados para os mercados de comunicações móveis.

6
  • PAULO VITOR SILVA
  • Regulador Eletromagnético de Frequência Aplicado no Controle de Velocidade de Geradores Eólicos

  • Advisor : RICARDO FERREIRA PINHEIRO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ANDRES ORTIZ SALAZAR
  • FABIANO SALVADORI
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • RICARDO FERREIRA PINHEIRO
  • VLADIMIRO HENRIQUE BARROSA PINTO DE MIRANDA
  • Data: May 11, 2015


  • Show Abstract
  • A necessidade constante de novas fontes de energias renováveis vem promovendo cada vez mais o aumento de investimentos nessa área. Dentre essas fontes, a energia eólica vem tomando grande destaque. Torna-se importante promover a busca pelo aprimoramento das tecnologias envolvidas nas topologias de aerogeradores, buscando alternativas que aumentem o rendimento obtido, apesar da irregularidade da velocidade do vento.

    Este trabalho apresenta um novo sistema para controle de velocidade, aqui aplicado em aerogeradores, o Regulador Eletromagnético de Frequência (REF). Um dos dispositivos mais utilizados em algumas topologias são as caixas de engrenagens mecânicas que, além de uma vida útil curta, representam frequentemente, fontes de ruído e defeitos. O REF dispensa essas caixas de transmissão, representando um avanço tecnológico, utilizando para isso uma máquina de indução adaptada, na qual o estator passa a ser móvel, solidário ao eixo da turbina.

    Na topologia utilizada neste trabalho, o REF também permite dispensar o uso de conversores eletrônicos para estabelecer o acoplamento entre o aerogerador e a rede elétrica, razão pela qual também proporciona a possibilidade de obtenção de geração em corrente alternada, com tensão e frequência constantes, onde não exista a rede elétrica.

    Responsável pelo controle da velocidade mecânica do gerador, o REF pode ser útil em outros sistemas de transmissão onde o controle de velocidade mecânica de saída seja o objetivo.

    Além disso, por operar através da combinação de duas entradas, uma mecânica e outra elétrica, o REF multiplica as possibilidades de aplicações por ser apto ao acoplamento sinérgico entre energias de matrizes diferentes, e, por tais motivos, possibilita que as diversas fontes de energia envolvidas sejam desacopladas da rede, sendo o gerador síncrono o responsável pela conexão do sistema com a rede elétrica, simplificando as estratégias de controle quanto à potência injetada na mesma.

    Resultados de simulação e experimentais são apresentados no decorrer do trabalho, voltados a um aerogerador, validando a proposta em relação a eficiência no controle de velocidade do sistema para diferentes condições de vento.

7
  • JULIO CESAR PAULINO DE MELO
  • Autonomic Hardware Manager - Uma Sistema de Hardware Autonomico Utilizando Solução de Repositório Ativo de Componentes

  • Advisor : LUIZ EDUARDO CUNHA LEITE
  • COMMITTEE MEMBERS :
  • ALISSON VASCONCELOS DE BRITO
  • ELMAR UWE KURT MELCHER
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • LUIZ EDUARDO CUNHA LEITE
  • MONICA MAGALHAES PEREIRA
  • Data: May 29, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • Esta tese tem como objetivo desenvolver e implementar um sistema Autonômico de Hardware, capaz de gerenciar o hardware em operação em dispositivos reconfiguráveis, possibilitando mecanismos de manipulação e geração de hardware usando a metodologia de Repositório Ativo de Componentes. O sistema será usado para conceber sistemas de hardware sensíveis à contexto, provendo métodos para modelar e adaptar um sistema de hardware ao Contexto de Operação em que se encontra.

    A solução consiste no desenvolvimento uma arquitetura de Hardware-Software chamada Autonomic Hardware Manager, um Repositório Ativo de componentes de hardware, que irá gerenciar e gerar hardware durante a operação do sistema. Um metamodelo e método de modelagem de Contexto de Operação para sistemas de hardwarware será desenvolvido e adicionado ao repositório ativo, fazendo com que o mesmo se torne sensível ao contexto. Para efeitos de prova do funcionamento da arquitetura, experimentos são propostos e implementados visando provar as hipóteses e completar os objetivos da tese.
8
  • ADERSON JAMIER SANTOS REIS
  • Um Controlador Dual Subótimo com Fator de Peso Variável no Tempo

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • VICENTE DELGADO MOREIRA
  • Data: Jun 12, 2015


  • Show Abstract
  • O presente trabalho insere-se no âmbito dos sistemas de controle duais adaptativos.
    O controle dual contempla uma solução ótima formulada para um problema na teoria
    de controle estocástico no qual envolve incertezas e variações de parâmetros no tempo.
    Este trabalho propõe uma modificação em um controlador dual subótimo para sistemas
    discretos no tempo. O controlador ótimo dual almeja um balanceamento correto que
    busca, ao mesmo tempo, manter um bom controle e obter pequenos erros de estimativas.
    O sinal de controle é calculado de maneira a minimizar a variação da saída do sistema com
    base num valor de referência um passo adiante. A ideia deste controlador dual subótimo é
    adicionar termos simples na matriz de covariância dos parâmetros estimados dois passos
    adiante. Um algoritmo adaptativo é utilizado para o ajuste do parâmetro de projeto l
    a cada passo do sistema. O desempenho do controlador proposto é avaliado através do
    método de simulações Monte Carlo.

9
  • LEONARDO WAYLAND TORRES SILVA
  • Otimização do Controle do Diagrama de Radiação de Radares de Varredura para Rastreio de Foguetes Usando o Método GAMMC para o Caso Planar (GAMMC-P)

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRES ORTIZ SALAZAR
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • Data: Jun 19, 2015


  • Show Abstract
  • Os centros de lançamento e rastreio têm por finalidade realizar atividades científicas e comerciais com veículos aeroespaciais. Os Sistemas de Rastreio de Foguetes (SRF) integram a infraestrutura desses centros, sendo responsáveis pela coleta e processamento dos dados da trajetória dos veículos. Os sensores dos SRFs normalmente são Radares com Refletores Parabólicos (RRPs), mas também é possível usar radares com arranjos de antenas, chamados de Arranjos de Varredura (AVs), originando os Radares com Arranjos de Varredura (RAVs). Nos AVs, o sinal de alimentação de cada elemento radiante do arranjo pode ser ajustado para fazer o controle eletrônico do diagrama de radiação, a fim de aumentar as funcionalidades e reduzir as manutenções do sistema. Com isso, nos projetos de implantação e reutilização de RAVs, a modelagem está sujeita a várias combinações de sinais de alimentação, produzindo um problema de otimização complexo, devido ao grande número de soluções disponíveis. Para solucionar tal problema, é possível usar métodos de otimização off-line, tais como Algoritmos Genéticos (AGs), cujas soluções calculadas são armazenadas para aplicações on-line. Nesse contexto, o método do Algoritmo Genético com Crossover Máximo-Mínimo (Genetic Algorithm with Maximum-Minimum Crossover – GAMMC) foi usado para desenvolver o algoritmo GAMMC-P, que otimiza a etapa de modelagem do controle do diagrama de radiação de AVs planares. Comparado a um AG com recombinação convencional, o GAMMC tem uma abordagem diferente, pois realiza a recombinação de indivíduos mais aptos com indivíduos menos aptos, para aumentar a diversidade genética da população, evitando a convergência prematura, aumentando o fitness e reduzindo o tempo de processamento. Assim, o GAMMC-P utiliza um algoritmo reconfigurável, com múltiplos objetivos, codificação real diferenciada e o operador genético MMC, tendo atingido com sucesso os requisitos propostos para diferentes condições de operação de um RAV planar.
     

     

10
  • NATHALEE CAVALCANTE DE ALMEIDA
  • Técnicas de Conformação de Feixe em Arranjo de Antenas utilizando Aprendizagem por Reforço

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • JOSE PATROCINIO DA SILVA
  • MARCELO AUGUSTO COSTA FERNANDES
  • JORGE DANTAS DE MELO
  • FABBRYCCIO AKKAZZHA CHAVES MACHADO CARDOSO
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • Data: Jun 19, 2015


  • Show Abstract
  • A conformação de feixe, também conhecida como beamforming, é uma técnica bastante utilizada em diversas áreas. Com o auxílio de um arranjo de antenas, a conformação de feixe tem como objetivo minimizar a contribuição de interferentes de direções desconhecidas, enquanto captura o sinal desejado em uma dada direção. Nesta tese são propostas técnicas de conformação de feixe utilizando Aprendizagem por Reforço (AR) através do algoritmo Q-Learning, em arranjo de antenas. Uma das propostas é utilizar AR para encontrar a política ótima de seleção entre a conformação de feixe (CF) e o controle de potência (CP) a fim de aproveitar melhor as características individuais de cada uma delas para um determinado valor de Relação Sinal-Ruído Interferente (SINR). Outra proposta é utilizar AR na determinação da política ótima entre algoritmos de conformação cega de feixes, CMA (Algoritmo do Módulo Constante) e DD (Decisão Direta) em ambientes com multipercurso, ou seja, com diversas reflexões do mesmo sinal. Através de simulações destas propostas foi possível concluir que a AR pode ser eficaz para implementar uma política de chaveamento entre diferentes técnicas buscando sempre aproveitar características positivas de cada uma delas.

11
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • Algoritmo Modificado de PSO Matricial aplicado a Identificação de Sistemas com Análise de Convergência

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDRE LAURINDO MAITELLI
  • DANIELLE SIMONE DA SILVA CASILLO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • VICENTE DELGADO MOREIRA
  • Data: Jul 6, 2015


  • Show Abstract
  • Recentemente diversas técnicas de computação evolucionárias têm sido utilizadas em áreas como estimação de parâmetros de processos dinâmicos lineares e não lineares ou até sujeitos a incertezas. Isso motiva a utilização de algoritmos como o otimizador por nuvem de partículas (PSO) nas referidas áreas do conhecimento. Porém, pouco se sabe sobre a convergência desse algoritmo e, principalmente, as análises e estudos realizados têm se concentrado em resultados experimentais. Por isso, é objetivo deste trabalho propor uma nova estrutura para o PSO que permita analisar melhor a convergência do algoritmo de forma analítica. Para isso, o PSO é reestruturado para assumir uma forma matricial e reformulado como um sistema linear por partes. As partes serão analisadas de forma separada e será proposta a inserção de um fator de esquecimento que garante que a parte mais significativa deste sistema possua autovalores dentro do círculo de raio unitário. Também será realizada a análise da convergência do algoritmo como um todo, utilizando um critério de convergência quase certa, aplicável a sistemas chaveados. Na sequência, serão realizados testes experimentais de maneira a verificar o comportamento dos autovalores após a inserção do fator de esquecimento. Posteriormente, os algoritmos de identificação de parâmetros tradicionais serão combinados com o PSO matricial, de maneira a tornar os resultados da identificação tão bons ou melhores que a identificação apenas com o PSO ou, apenas com os algoritmos tradicionais. Os resultados mostram a convergência das partículas em uma região delimitada e que as funções obtidas após a combinação do algoritmo PSO matricial com os algoritmos convencionais, apresentam maior generalização para o sistema apresentado. As conclusões a que se chega é que a hibridização, apesar de limitar a busca por uma partícula mais apta do PSO, permite um desempenho mínimo para o algoritmo e ainda possibilita melhorar o resultado obtido com os algoritmos tradicionais, permitindo a representação do sistema aproximado em quantidades maiores de frequências.

12
  • MELINDA CESIANARA SILVA DA CRUZ
  • Metodologia de estimação de estados para tratamento de medições errôneas e registros não sincronizados em algoritmos de localização de faltas em linhas de transmissão.

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • BENEMAR ALENCAR DE SOUZA
  • DENIS VINICIUS COURY
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Jul 17, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • O desempenho de algoritmos para localização de faltas em linhas de transmissão está diretamente relacionado à exatidão dos seus dados de entrada. Assim, fatores como erros nos parâmetros da linha de transmissão, falhas na sincronização de registros oscilográficos e erros em medições de tensão e de corrente podem influenciar de forma significativa as ferramentas que usam dados errôneos para indicar o local de defeitos. Este
    trabalho apresenta uma nova metodologia para localização de faltas em linhas de transmissão, baseada na teoria de estimação de estados, de forma a determinar o local mais provável de ocorrência de curtos-circuitos através da consideração de erros sistemáticos realísticos que podem estar presentes nas medições de tensão e de corrente. O algoritmo foi implementado em duas etapas: pré-falta e pós-falta. Na primeira etapa, admitindo dados não sincronizados, estima-se o ângulo de sincronização e os parâmetros de sequência
    positiva da linha de transmissão, e na segunda, estima-se a distância de falta. Além de calcular o valor mais provável para a distância de falta, a partir da consideração de erros nas medições, a variância associada a esta distância também é determinada, usando definições da teoria de erros. Essa é uma das principais contribuições deste trabalho, visto que, a partir o algoritmo proposto, é possível determinar uma região de provável incidência da falta, com aproximadamente 95,45% de confiança. Testes para avaliação e validação da
    metodologia foram realizados a partir de registros reais de falta e a partir de simulações de sistemas fictícios de transmissão no software ATP. Os resultados obtidos são relevantes para mostrar que o estimador de localização de faltas desenvolvido apresenta bom desempenho mesmo adotando variâncias realísticas.

13
  • BRUNO MARQUES FERREIRA DA SILVA
  • Registro Global de Nuvens de Pontos RGB-D em Tempo Real Usando Fluxo Óptico e Marcadores

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • BRUNO MOTTA DE CARVALHO
  • JUSTO EMÍLIO ALVAREZ JÁCOBO
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • ROSIERY DA SILVA MAIA
  • Data: Jul 31, 2015


  • Show Abstract
  • O registro de nuvens de pontos capturadas por sensores de profundidade é uma importante etapa em aplicações de reconstrução 3D. Em diversos casos como localização e mapeamento para robótica ou realidade aumentada para entretenimento, o registro deve ser realizado não só com precisão estrita, como também na frequência de dados de aquisição do sensor. Com o objetivo de registrar nuvens de pontos de sensores RGB-D (p. ex. Microsoft Kinect), é proposto nesta tese o uso do algoritmo de fluxo óptico piramidal esparso para registro incremental a partir de dados de aparência e profundidade. O erro acumulado inerente ao processo incremental é posteriormente reduzido, através do uso de um marcador artificial e minimização de erro por otimização em grafo de poses. Resultados experimentais obtidos após o processamento de diversos conjuntos de dados RGB-D validam o sistema proposto por esta tese para aplicações de odometria visual, SLAM visual e digitalização de objetos em tempo real.

14
  • HELTON MAIA PEIXOTO
  • Modelagem dos efeitos da irradiação luminosa no cérebro de camundongos e rastreamento de neurônios durante experimentos de microscopia de fluorescência

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • CICILIA RAQUEL MAIA LEITE
  • HELIANA BEZERRA SOARES
  • RICHARDSON NAVES LEAO
  • WILFREDO BLANCO FIGUEROLA
  • Data: Jul 31, 2015


  • Show Abstract
  • As proteínas fluorescentes constituem uma ferramenta fundamental em vários campos da biologia, pois permitem enxergar o desenvolvimento de estruturas e processos dinâmicos de células em tecido vivo, com o auxílio da microscopia de fluorescência. A Optogenética é outra técnica que atualmente ganha destaque na Neurociências e que, de forma geral, permite ativar/desativar neurônios a partir da irradiação luminosa de certos comprimentos de onda sobre as células que possuem canais iônicos sensíveis à luz, e ainda pode ser utilizada concomitantemente com as proteínas fluorescentes. Esta tese possui dois objetivos principais. Inicialmente, são estudados os efeitos da interação da luz e o cérebro de camundongos para aplicações em experimentos de Optogenética. Nesta etapa, são modelados, a partir de características do cérebro de camundongos e utilizando a teoria de Kulbelka-Munk, os efeitos de absorção e espalhamento da luz, em comprimentos de onda específicos, em função da distância de penetração no tecido cerebral. Além disso, são modeladas as variações de temperatura utilizando o método dos elementos finitos na resolução da equação de bioaquecimento de Pennes, com o auxílio do COMSOL Multiphysics Modeling Software 4.4, onde são simulados protocolos de estimulação luminosa, tipicamente utilizados em Optogenética. Posteriormente, são desenvolvidos algoritmos computacionais capazes de reduzir a exposição das células nervosas à irradiação luminosa necessária à visualização da fluorescência emitida por elas. Nesta etapa, são descritas as técnicas de processamento digital de imagens desenvolvidas para uso em microscopia de fluorescência, com o intuito de reduzir a exposição das amostras de cérebro à luz contínua, responsável pela excitação dos fluorocromos. As técnicas de processamento de imagens desenvolvidas e utilizadas são capazes de rastrear, em tempo real, uma região de interesse (ROI) e substituir a fluorescência emitida pelas células por uma máscara virtual, como resultado da sobreposição da ROI que está sendo rastreada e a informação de fluorescência previamente armazenada, mantendo a localização das células independentemente do tempo de exposição à luz fluorescente. Em resumo, esta tese pretende entender os efeitos da irradiação luminosa no cérebro, no contexto da Optogenética, além de fornecer uma ferramenta computacional que possa auxiliar certos experimentos em microscopia de fluorescência na redução do desvanecimento (bleaching) das amostras e dos danos (photodamage) causados ao tecido devido à intensa exposição das estruturas fluorescentes à luz.

15
  • MARCIO VALERIO DE ARAUJO
  • Geração de padrão de marcha adaptável para uma órtese ativa de membros inferiores.
  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • PABLO JAVIER ALSINA
  • DANILO ALVES PINTO NAGEM
  • WALLACE MOREIRA BESSA
  • ANFRANSERAI MORAIS DIAS
  • ANSELMO FRIZERA NETO
  • Data: Jul 31, 2015


  • Show Abstract
  • Atualmente com o crescente aumento de dispositivos robóticos destinados para aplicação na área de mobilidade de pessoas que sofreram algum tipo de lesão medular, se faz necessário desenvolver novas ferramentas para tornar tais equipamentos mais adaptáveis, seguros e autônomos. Para que as órteses robóticas que auxiliam na locomoção de pessoas paraplégicas possam desempenhar sua função, estas devem ser capazes de reproduzir os movimentos perdidos com o máximo de fidelidade e segurança em ambientes que eventualmente possam conter obstáculos de diferentes tipos como buracos, escadas e calçadas. As órteses robóticas para membros inferiores têm a capacidade de caminhar, subir e descer degraus, todavia, esses movimentos, na maioria das vezes, não se adaptam ao ambiente, sendo assim, para uma órtese robótica que foi projetada para subir um degrau com uma determinada altura ao se deparar com um degrau maior provavelmente não conseguirá realizar essa tarefa com a mesma segurança. Para solucionar esse e outros problemas, esse trabalho apresenta um Sistema de Auxílio à Locomoção (SAL) dotado de um planejador de passos e um gerador de referências angulares com características antropomórficas para a órtese robótica Ortholeg. O SAL utiliza dados antropométricos do usuário para gerar um padrão de marcha personalizado, dessa forma, a órtese em questão é capaz de adaptar o tamanho do passo para não colidir com obstáculos presentes no ambiente e transpor buracos com diversos tamanhos, subir e descer escadas e calçadas com diferentes valores de altura e comprimento. Para desenvolver o sistema de auxílio à locomoção foram adaptadas técnicas de planejamento de caminho, usadas a princípio em robôs bípedes. São apresentados vários experimentos que mostram a órtese Ortholeg realizando alguns movimentos com características antropomórficas para diferentes distâncias de caminhada e três tipos de obstáculos: degrau, buraco e calçada. A autonomia adquirida com a utilização do sistema de planejamento apresentado facilita a utilização de órteses robóticas como também garante uma maior segurança ao usuário.

     

16
  • FELIPE DENIS MENDONCA DE OLIVEIRA
  •  

    FTE-LEACH: UM PROTOCOLO ENERGETICAMENTE EFICIENTE E TOLERANTE A FALHAS APLICADO ÀS REDES INDUSTRIAIS DE SENSORES SEM FIO 

     

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ANDRES ORTIZ SALAZAR
  • CLAUDIA MARIA FERNANDES ARAÚJO RIBEIRO
  • KARLA DARLENE NEPOMUCENO RAMOS
  • Data: Aug 3, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • Uma Rede de Sensores sem Fio (RSSF) consiste de dispositivos distribuídos em uma área com a finalidade de monitorar variáveis físicas, tais como temperatura, pressão, vibração, movimento e condições ambientais em locais onde as redes cabeadas seriam complicadas ou impraticáveis de serem implementadas, por exemplo, aplicações industriais de difícil acesso, monitoramento e controle de poços petrolíferos terrestres ou marítimos, no acompanhamento de extensas áreas de cultivo agrário e animal, entre outros.

                Para ser viável, uma RSSF deve possuir requisitos importantes, tais como baixo custo, baixa latência e, principalmente, baixo consumo de energia.  Entretanto, para garantir tais requisitos, essas redes sofrem limitação de recursos, além de, eventualmente, serem utilizadas em ambientes hostis, levando a altas taxas de falhas, tais como roteamentos segmentados, perda de mensagens, reduzindo a eficiência podendo chegar, inclusive, a comprometer a rede como um todo.

    Este trabalho tem por objetivo apresentar o FTE-LEACH, um protocolo de roteamento energeticamente eficiente e tolerante a falhas, mantendo a eficiência na comunicação e na disseminação de dados.  Tal protocolo foi desenvolvido baseado no padrão IEEE 802.15.4 e voltado às redes industriais com recursos energéticos limitados.  

17
  • FUAD MOUSSE ABINADER JUNIOR
  • Distributed Strategies for the Coexistence of Broadband Wireless Networks in Unlicensed Bands

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • JOSE PATROCINIO DA SILVA
  • MARCIO EDUARDO DA COSTA RODRIGUES
  • VICENTE ANGELO DE SOUSA JUNIOR
  • ANDRE NOLL BARRETO
  • TARCISIO FERREIRA MACIEL
  • Data: Aug 21, 2015


  • Show Abstract
  • A crescente demanda por tráfego de dados em redes de acesso de banda larga sem fio à Internet requer tanto o desenvolvimento de novas tecnologias de acesso mais eficientes quanto que novas faixas de frequência do espectro eletromagnético sejam alocadas para este fim. A introdução de um grande número de small cells em redes celulares aliado à adoção de forma complementar de tecnologias de Wireless Local Area Networks (WLAN) em faixas de espectro não-licensiadas tem se verificado como um dos conceitos mais promissores. Uma das alternativas dentro deste conceito é a introdução de small cells Long Term Evolution (LTE) operando em espectro não-licensiado Industrial, Science and Medical (ISM) de 5Gigahertz (GHz), numa abordagem conhecida como Unlicensed LTE (LTE-U). No entanto, a tecnologia de acesso de banda larga sem fio IEEE 802.11 (Wi-Fi) já se encontra bastante difundida e operando nessa faixa de espectro, o que pode acarretar problemas de desempenho derivados da coexistência de ambas as tecnologias na mesma faixa de espectro. Além disso, existe a necessidade de melhorar a operação do Wi-Fi para que possa suportar cenários com um grande número de redes vizinhas, cada uma com um grande número de nós (conhecido como "‘implantação densa"’). É sabido que o desempenho global das redes Wi-Fi cai de forma acentuada com o aumento de número de dós compartilhando o canal, e portanto mecanismos para aumentar sua eficiência espectral se fazem necessários. Este trabalho é dedicado ao problema da coexistência entre diferentes sistemas de acesso à banda larga sem fio operando nas mesmas faixas de espectro não-licensiado, e como resolver esses problemas por meio de algoritmos de coordenação distribuídos. O problema da coexistência entre redes diferentes (i.e. LTE e Wi-Fi) e o problema de coexistência entre diferentes redes da mesma tecnologia (i.e. múltiplas Overlapping Basic Subscriber Sets (OBSSs) Wi-Fi) é analisado qualitativamente e quantitativamente via simulação sistêmica, e suas principais questões a serem enfrentadas são identificadas. Com base nisso, soluções distribuídas de coordenação são propostas e avaliadas via simulação sistêmica tanto para o problema de coexistência inter-tecnologias como para o problema de coexistência intra-tecnologia. Os resultados das avaliações indicam que as soluções concebidas provêm ganhos significativos ante uma situação de coexistência sem coordenação distribuída.

18
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • Critério de Correntropia no Treinamento de Redes Fuzzy Wavelet Neural Networks para Identificação de Sistemas Dinâmicos Não Lineares 

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRE LAURINDO MAITELLI
  • MARCONI CAMARA RODRIGUES
  • JOSE MEDEIROS DE ARAUJO JUNIOR
  • OSCAR GABRIEL FILHO
  • Data: Sep 3, 2015


  • Show Abstract
  • O grande interesse pela identificação não linear de sistemas dinâmicos deve-se, principalmente, ao fato de que uma grande quantidade dos sistemas reais são complexos e precisam ter suas não linearidades consideradas para que seus modelos possam ser utilizados com sucesso em aplicações, por exemplo, de controle, predição, inferência, entre outros. O presente trabalho pretende analisar a aplicação das redes Fuzzy Wavelet Neural Network (FWNN) na identificação de sistemas não lineares sujeitos a ruídos e outliers. Esses elementos, geralmente, influenciam no procedimento de identificação, ocasionando interpretações errôneas em relação ao comportamento dinâmico do sistema. A FWNN combina em uma única estrutura a capacidade de lidar com incertezas da lógica fuzzy, as características de multirresolução da teoria wavelet e as habilidades de aprendizado e generalização das redes neurais artificiais. Normalmente, o aprendizado dessas redes é realizado por algum método baseado em gradiente, tendo o erro médio quadrático como função de custo. Este trabalho propõe a substituição dessa tradicional função por uma medida da Teoria da Informação, denominada correntropia. Esta medida de similaridade permite que momentos estatísticos de ordem superiores possam ser considerados durante o processo de treinamento. Por esta razão, ela se torna mais apropriada para distribuições de erro não gaussianas e faz com que o treinamento apresente menor sensibilidade à presença de outliers. Para avaliar esta substituição, modelos FWNN são obtidos na identificação de dois estudos de caso: um sistema real não linear, consistindo em um tanque de múltiplas seções, e um sistema simulado baseado em um modelo biomecânico da articulação do joelho humano. Os resultados obtidos demonstram que a utilização da correntropia como função custo no algoritmo da retropropagação do erro torna o procedimento de identificação utilizando redes FWNN mais robusto aos outliers. Entretanto, isto somente pode ser alcançado a partir do ajuste adequado da largura do kernel gaussiano da correntropia.

19
  • CARLOS ALBERTO DE ALBUQUERQUE SILVA
  • IMPLEMENTAÇÃO DE UMA MATRIZ DE NEURÔNIOS DINAMICAMENTE RECONFIGURÁVEL PARA DESCRIÇÃO DE TOPOLOGIAS DE REDES NEURAIS ARTIFICIAIS MULTILAYER PERCEPTRONS

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DAVID SIMONETTI BARBALHO
  • JORGE DANTAS DE MELO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • DANNIEL CAVALCANTE LOPES
  • KARLA DARLENE NEPOMUCENO RAMOS
  • Data: Sep 4, 2015


  • Show Abstract
  • As Redes Neurais Artificiais (RNAs), que constituem uma das ramificações da Inteligência Artificial (IA), estão sendo empregadas como solução para vários problemas complexos, existentes nas mais diversas áreas. Para a solução destes problemas torna-se indispensável que sua implementação seja feita em hardware. Em meio as estratégias a serem adotadas e satisfeitas durante a fase de projeto e implementação das RNAs em hardware, as conexões entre os neurônios são as que necessitam de maior atenção. Recentemente, encontram-se RNAs implementadas tanto em circuitos integrados de aplicação específica (Application Specific Integrated Circuits - ASIC) quanto em circuitos integrados, configurados pelo usuário, a exemplo dos Field Programmable Gate Array (FPGAs), que possuem a capacidade de serem reconfigurados parcialmente, em tempo de execução, formando, portanto, um Sistema Parcialmente Reconfigurável (SPR), cujo emprego proporciona diversas vantagens, tais como: flexibilidade na implementação e redução de custos. Tem-se observado um aumento considerado no uso destes dispositivos para a implementação de RNAs. Diante do exposto, propõe-se a implementação de uma matriz de neurônios dinamicamente reconfigurável no FPGA Virtex 6 da Xilinx, descrita em linguagem de hardware e que possa absorver projetos baseados em plataforma de sistemas embarcados, dedicados ao controle distribuído de equipamentos normalmente utilizados na indústria. Propõe-se ainda, que a configuração das topologias das RNAs que possam vir a ser formadas, seja realizada via software.

20
  • ALUISIO IGOR REGO FONTES
  • Uso de Correntropia na Generalização de Funções Cicloestacionárias e Aplicações para a Extração de Características de Sinais Modulados

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • SAMUEL XAVIER DE SOUZA
  • EDMAR CANDEIA GURJÃO
  • GUILHERME DE ALENCAR BARRETO
  • Data: Sep 11, 2015


  • Show Abstract
  • A extração de informações de sinais aleatórios é um problema frequente e relevante em muitas aplicações de processamento digital de sinais. Nos últimos anos, diferentes métodos têm sido utilizados para a parametrização de sinais ou obtenção de descritores eficientes de suas características. Quando os sinais aleatórios possuem propriedades es- tatísticas cicloestacionárias, as Funções de Autocorrelação Cíclica (CAF) e a Densidade Espectral Cíclica (SCD) podem ser utilizadas na obtenção de informações cicloestacioná- rias de segunda ordem. Entretanto, em sinais não-gaussianos, as informações cicloestaci- onárias de segunda ordem são fracas e, neste caso a análise cicloestacionária deve ocorrer sobre informações estatísticas de ordem superior. Este trabalho propõe uma nova ferra- menta matemática para a análise cicloestacionária de ordem superior baseada na função de correntropia. Especificamente, a teoria de análise cicloestacionária é revisitada sob um enfoque de teoria da informação, e as Funções de Correntropia Cíclica (CCF) e Densidade Espectral de Correntropia Cíclica (CCSD) são definidas. É comprovado analiticamente que a CCF contém informações de momentos cicloestacionários de segunda ordem e de ordem superior, sendo uma generalização da CAF. O desempenho dessas novas funções, na extração de características cicloestacionárias de ordem superior, é analisado em um cenário de comunicação sem fio com ruído não-gaussiano. 

21
  • ANTONIO HIGOR FREIRE DE MORAIS
  • Fuzzy Angel: Uma Arquitetura Distribuída de Telemedicina Para Monitoramento de Pacientes com Esclerose Lateral Amiotrófica

  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • GLAUCIO BEZERRA BRANDAO
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Nov 20, 2015


  • Show Abstract
  • A Esclerose Lateral Amiotrófica (ELA) é uma doença neurodegenerativa caracterizada pela fraqueza muscular progressiva que leva o paciente à morte, geralmente devido a complicações respiratórias. Assim, ao passo que a doença progride o paciente precisará de ventilação não-invasiva (VNI) e monitoramento constante. Esta tese apresenta uma arquitetura distribuída para monitoramento domiciliar de ventilação noturna não-invasiva (VNNI) em pacientes com ELA. A implementação desta arquitetura utilizou um computador de placa única (Single Board Computer) e dispositivos móveis localizados na casa do paciente para mostrar mensagens de alerta para os cuidadores do paciente e um servidor web para monitoramento remoto pela equipe de saúde. A arquitetura utilizou um software baseado em lógica fuzzy e visão computacional para capturar os dados da tela do ventilador mecânico e gerar mensagens de alerta com instruções para os cuidadores. O experimento de monitoramento foi realizado com 29 pacientes por 7 horas contínuas diariamente durante 5 dias gerando um total de 126000 amostras para cada variável monitorada com uma taxa de amostragem de uma amostra por segundo. A arquitetura do sistema foi avaliada com relação a taxa de acerto para reconhecimento de caracteres e respectiva correção através de um algoritmo para detecção e correção de erros. Além disso, a equipe de saúde avaliou o sistema com relação aos intervalos de tempo em as mensagens de alertas foram geradas e se as estas estavam corretas. Dessa forma, o sistema apresentou uma média geral de acertos de 98,72%, e no pior caso 98,39%. Quanto às mensagens a serem geradas, o sistema também concordou em 100% com a avaliação geral, tendo havido discordância em apenas dois casos com um dos avaliadores.

22
  • OTÁVIO PAULINO LAVOR
  • Bi Anisotropia em Antenas de Microfita Retangular e Estruturas Circulares Modificadas

     


  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO CESAR CHAVES FERNANDES
  • HUMBERTO DIONISIO DE ANDRADE
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOSE PATROCINIO DA SILVA
  • MARINALDO PINHEIRO DE SOUSA NETO
  • Data: Nov 20, 2015


  • Show Abstract
  • As antenas de microfita na sua forma mais simples são compostas por um plano de terra e um substrato dielétrico que sustenta uma fita condutora. Como estas antenas apresenta algumas limitações, este trabalho apresenta um estudo de substratos anisotrópicos, bem como alguns resultados em antenas de microfita com patch circular visando superar estas limitações, em especial nas aplicações em tecnologia 4G. Esses substratos anisotrópicos são aqueles em que permissividade elétrica e permeabilidade magnética possam ter a sua forma mais geral que é um tensor de ordem dois. O estudo consiste de uma análise teórica dos substratos, bem como o desenvolvimento de um formalismo matemático, o método da Linha de Transmissão Transversa, da aplicação destes substratos em antenas de microfita. Dentre os substratos utilizados neste estudo, estão os ferrimagnéticos e os Metamateriais, em que algumas miniaturizações são alcançadas. Para antenas com patch circular, são considerados arranjos e planos te terra modificados a fim de alcançar melhoria nos parâmetros, em especial ganho e largura de banda. São feitas diversas simulações e protótipos são construídos para que os valores medidos sejam comparados com os valores simulados.

     


23
  • MARCELO HENRIQUE RAMALHO NOBRE
  • Contribuições em Escalonamento e Análise de Desempenho de Redes WirelessHART

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • CARLOS MANUEL DIAS VIEGAS
  • DANIEL GOUVEIA COSTA
  • IVAN MULLER
  • Data: Nov 23, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • A comunicação sem fios é uma tendência no ambiente industrial atualmente e nessa tendência temos o WirelessHART como uma das principais tecnologias. Com essa situação, é natural que melhorias no desempenho sejam buscadas e um dos principais caminhos para isso passa pelo desenvolvimento de algoritmos de escalonamento e roteamento. Nesta tese é apresentado uma revisão da literatura sobre as principais soluções em escalonamento e roteamento desenvolvidas especificamente para a tecnologia WirelessHART. Além disso propõe um novo Algoritmo de escalonamento chamando Escalonamento Flow que visa melhorar aspectos de flexibilidade e de utilização do superframe. Para propósitos de validação, é desenvolvido e utilizado um módulo de simulação para o Network Simulator 3 (NS-3) que modela aspectos como posicionamento, atenuação de sinal e consumo de energia além de prover simulações mais exatas por meio de configurações de erro individuais para cada link.  Este módulo também possibilita a geração do superframe de escalonamento a partir do grafo de roteamento utilizando os algoritmos Flow e Han. Para a validação do novo algoritmo são realizados experimentos comparativos entre o algoritmo Han e algoritmo Flow, avaliando critérios de alocação de links, delay e taxa de ocupação de superframe. Para validação da camada física do módulo de simulação, o escalonamento e o roteamento são configurados estaticamente e são desenvolvidos experimentos de confiabilidade e consumo de energia com topologias validadas na literatura e com variações de probabilidades de erro.


24
  • JOSE HAROLDO CAVALCANTE DE MORAIS
  • Evoluções nas modelagens de substratos artificiais (metamateriais) com práticas experimentais em antenas de microfita

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARINALDO PINHEIRO DE SOUSA NETO
  • SANDRO GONCALVES DA SILVA
  • Data: Dec 1, 2015


  • Show Abstract
  • Esse trabalho tem como objetivo apresentar configurações de substratos dielétricos inovadores projetados e fabricados a partir de estruturas metamateriais. Para isso, são avaliados diversos fatores que podem influenciar no seu desempenho. A princípio, foi feito um levantamento bibliográfico a respeito dos temas, que estão relacionados com as pesquisas sobre: materiais dielétricos, metamateriais e interferometria óptica. São estudados, pesquisados e desenvolvidos dois projetos experimentais propostos, que comprovam a eficiência de métodos, para se alcançar a permeabilidade magnética negativa na formação de metamateriais. O primeiro projeto é a produção de uma nova estrutura, com u anel ressoador triangular equilateral (Split Equilateral Triangle Resonator - SETR). O segundo projeto: aplica os princípios da interferometria óptica, especialmente, com o interferômetro de Fabry-Perot. Técnicas para obtenção dos dispositivos que complementam a placa metamaterial como substrato foram pesquisadas na literatura e exemplificadas principalmente por meio de simulações e medições. Foram feitas comparações, simulações e medições de estruturas convencionais e especiais. As experiências se concentram nas evoluções e modelagens de substratos metamateriais com aplicações em antenas de microfita. As melhorias de alguns parâmetros de desempenho de antenas também são relatadas. As simulações das antenas foram feitas nos programas computacionais comerciais. Os resultados medidos foram obtidos com um analisador vetorial de redes da Rhode and Schwarz modelo ZVB 14.

25
  • JOSE MACEDO FIRMINO FILHO
  • LCD-OpenPACS: Sistema Integrado de Telerradiologia com Auxílio ao Diagnóstico de Câncer de Pulmão em Exames de Tomografia Computadorizada

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • BRUNO GOMES DE ARAUJO
  • HERTZ WILTON DE CASTRO LINS
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • KARILANY DANTAS COUTINHO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Dec 4, 2015


  • Show Abstract
  • O câncer de pulmão é uma das principais causas de morte no mundo. A sua alta taxa de mortalidade está relacionada com detecção da patologia em estágios avançados. De acordo com a literatura, a tomografia computadorizada (TC) é a modalidade de imagem mais indicada para a detecção precoce de nódulos pulmonares. No entanto, ela impacta diretamente na carga de trabalho dos radiologistas. Pesquisadores propuseram vários sistemas automatizados para auxiliar os radiologistas na detecção do câncer de pulmão. Entretanto, a utilização desses sistemas necessitava de alterações no fluxo de trabalho clínico e altos custos de implantação. Visando solucionar estas barreiras, o presente trabalho propõe uma nova abordagem para detecção de nódulos pulmonares, em exames de tomografia computadorizada (TC), baseado no descritor Histograma do Gradiente Orientada (HoG) e Máquina de Vetor de Suporte (SVM). Além disso, é proposto uma aplicação desta abordagem num sistema de telerradiologia, chamado LCD-OpenPACS, gratuito e código fonte aberto. Este sistema é uma extensão do sistema OpenPACS que é um sistema de comunicação e arquivamento de imagens médicas que possui código fonte aberto e multiplataforma desenvolvido pelo Laboratório de Inovação Tecnológica em Saúde (LAIS) do Hospital Universitário Onofre Lopes (HUOL). O método proposto é formado por cinco etapas: aquisição das imagens, segmentação, detecção de nódulos suspeitos, extração das características e classificação (eliminação de falsos positivos). O método proposto foi validado com 100 nódulos (identificados por, pelo menos, dois radiologistas) e 101 não nódulos (por exemplo, tecido, vasos sanguíneos e outras estruturas que não representavam nódulos cancerígenos) e apresentou uma sensibilidade de 98,03% com 9,6 falso positivo por caso em 0,18 s. O sistema detectou nódulos pulmonares cancerígenos (solitários, opacidade em vidro fosco e nódulos justavascular) entre 3 mm e 30 mm. Entretanto, a etapa de segmentação do sistema ainda não está apresentando resultados satisfatórios na presença de nódulos justapleurais e outras patologias graves que alteram a opacidade dos contornos pulmonares. As principais contribuições do presente trabalho foram o desenvolvimento do novo método de detecção de nódulos pulmonares e a proposta do sistema de telerradiologia que minimiza as alterações do fluxo de trabalho clínico e o custo de implantação, podendo ser utilizado pelo sistema de saúde brasileiro (SUS). Ainda são necessárias mais pesquisas para aperfeiçoar o sistema proposto, principalmente melhorar o processo de segmentação das imagens pulmonares. Como trabalhos futuros, propomos mensurar características dos nódulos (por exemplo, malignidade e volume), avaliar a evolução do tratamento oncológico e seu possível prognóstico.

26
  • RODRIGO SOARES SEMENTE
  • Estudo e Desenvolvimento de Algoritmos Criptográficos para Redes de Sensores Sem Fio, utilizando Técnicas de Programação Genética

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • FRANCISCO JOSÉ TARGINO VIDAL
  • JUAN MOISES MAURICIO VILLANUEVA
  • KARLA DARLENE NEPOMUCENO RAMOS
  • Data: Dec 7, 2015


  • Show Abstract
  • A criptografia é a principal forma de obter a segurança em qualquer rede. Mesmo em redes com grandes restrições de consumo de energia, processamento e memória, como as Redes de Sensores Sem Fio isso não é diferente. Objetivando melhorar o desempenho da criptografia, a segurança e o tempo de vida nessas redes, será proposto um novo algoritmo criptográfico desenvolvido através da técnica de Programação Genética.
    Para o desenvolvimento de critérios de aptidão do algoritmo criptográfico pelo algoritmo de Programação Genética, nove algoritmos criptográficos diferentes foram testados: AES, Blowfish, DES, RC6, Skipjack, Twofish, T-DES, XTEA e XXTEA. A partir desses testes uma função de aptidão foi desenvolvida levando em conta o tempo de execução, o espaço ocupado em memória, desvio máximo, desvio irregular, coeficiente de correlação, e efeito avalanche.
    A partir do algoritmo de Programação Genética otimizado foi criado o CRYSEED, um algoritmo para dispositivos de 8-bits, otimizado pra Redes de Sensores Sem Fio, i.e. baixa complexidade, pouco consumo de memória e boa segurança para as aplicações de sensoriamento e instrumentação.
     
     
27
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Contribuições para Estratégia de Controle Aplicada à Geração Fotovoltaica Interconectada à Rede Elétrica

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FLAVIO BEZERRA COSTA
  • VALENTIN OBAC RODA
  • ANTONIO MARCUS NOGUEIRA LIMA
  • LEONARDO RODRIGUES LIMONGI
  • Data: Dec 9, 2015


  • Show Abstract
  • Atualmente, as fontes renováveis têm o papel de cooperar com a geração convencional, em decorrência da limitação do sistema na entrega da potência requerida, da necessidade da redução dos efeitos indesejados das fontes que utilizam combustíveis fosseis e a dificuldade de construção de novas linhas de transmissão e/ou distribuição. Esta cooperação se dá por meio da geração distribuída. Desta forma, este trabalho propõem uma estratégia de controle para a interconexão de um sistema PV (do inglês, Photovoltaic) de geração distribuída com uma rede elétrica trifásica, por meio de um filtro de conexão do tipo LCL. A compensação da qualidade de energia no ponto de acoplamento comum (PAC) é realizada garantindo-se que a rede elétrica forneça, ou consuma apenas potência ativa e que suas correntes possuam baixo teor harmônico. Diferentemente das técnicas tradicionais, que necessitam de esquemas para a detecção harmônica, utilizando à estratégia HEBS (do inglês, Harmonic Extractor-Based Strategies), a técnica utilizada realiza a compensação harmônica sem a utilização desses esquemas, controlando as correntes de saída do sistema de uma forma indireta a partir do uso da estratégia BEBS (do inglês, Balanced Energy-Based Schemes). Para que haja um efetivo controle da tensão do barramento CC (Corrente Contínua) é utilizado o controlador robusto em modo dual DSM-PI (Proporcional Integral Dual em Modo Deslizante). Para o controle das correntes são usados controladores de dupla sequencia (DSC) que realizam a compensação da componente fundamental, do quinto e do sétimo harmônico. As correntes de referência são alinhadas ao ângulo de fase do vetor tensão da rede elétrica, obtido a partir do uso de um SRF-PLL (do inglês, Synchronous Reference Frame Phase-Locked-Loop). Com o intuito de obter a máxima potência dos painéis fotovoltaicos é utilizado um algoritmo de MPPT sem a necessidade de adição de sensores. Resultados experimentais são apresentados para demonstrar a eficácia do sistema de controle proposto.

28
  • GILMARA LINHARES DE ARAUJO
  • Método Híbrido para Projeto de Superfícies Seletivas em Frequência

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ALLAN DE MEDEIROS MARTINS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO CESAR CHAVES FERNANDES
  • HUMBERTO DIONISIO DE ANDRADE
  • JOSE PATROCINIO DA SILVA
  • Data: Dec 10, 2015
  • View Dissertation/Thesis  

  • Show Abstract
  • Esse trabalho apresenta uma técnica híbrida de projeto de superfícies seletivas em frequência, sobre uma camada dielétrica isotrópica, considerando diversas geometrias para os elementos das células unitárias. Especificamente, a técnica híbrida usa o método do circuito equivalente em conjunto com algoritmos genéticos, visando a síntese de estruturas com resposta singleband e dual-band. O método do circuito equivalente permite modelar a estrutura por meio de um circuito equivalente e também a obtenção de circuitos para diferentes geometrias. A partir da obtenção dos parâmetros desses circuitos, podem-se obter as características de transmissão e de reflexão das estruturas modeladas. Para obter a otimização das estruturas modeladas, de acordo com a resposta em frequência desejada, a ferramenta de otimização do Matlab optimtool mostrou-se de fácil utilização, permitindo explorar resultados importantes na análise de otimização. No trabalho, são apresentados resultados numéricos e experimentais para as características de transmissão de diferentes geometrias analisadas. Foram efetuadas comparações com resultados apresentados na literatura, tendo-se observado uma boa
    concordância nos casos analisados para estruturas com substratos isotrópicos.

2014
Dissertations
1
  • ANDRÉ SOFFIATTI
  • Estudo da Atenuação da Onda Eletromagnética em Meios Aquosos Utilizando Técnicas de Microondas

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • SANDRO GONCALVES DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Jan 10, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como objetivo principal investigar o comportamento da permissividade elétrica de materiais em meios aquosos por meio de método não invasivo. O problema analisado justifica-se na grande quantidade de alimentos que hoje apresentam esta característica de armazenagem, sendo de grande interesse a constante verificação de mudança de estado de conservação destes produtos. Assim, foi proposto um setup de medições e usando substâncias químicas conhecidas pode-se estudar o comportamento destes meios aquosos, sendo considerado nesta análise um meio de referência com uma permissividade elétrica conhecida. Este meio de referência é então aos poucos é modificado pela adição de uma das suas componentes e avaliado pela passagem de uma onda eletromagnética.

2
  • AGNALDO SOUZA CRUZ
  • Medição da densidade óssea através de ondas eletromagnéticas e classificação por MVS

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • SANDRO GONCALVES DA SILVA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • HUMBERTO DIONISIO DE ANDRADE
  • Data: Jan 13, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Esse trabalho apresenta uma proposta auxílio no diagnóstico da osteoporose por meio da medição a Densidade Mineral Óssea (DMO), sendo esta realizada por meio de ondas eletromagnéticas de sondagem associadas a um software para análise e classificação da DMO como alta ou baixa.

3
  • CARLOS EDUARDO GOMES DE ARAUJO
  • Utilização de Computador de Baixo Custo para Integração de Tecnologias em Automação Residencial

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • SAMAHERNI MORAIS DIAS
  • JUAN MOISES MAURICIO VILLANUEVA
  • Data: Jan 21, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Automação residencial é uma tendência inevitável para as habitações, uma vez que prover uma residência de dispositivos que propiciem conforto ao ambiente de forma automática não é mais uma solução cara e futurista. Além disso, as residências deverão estar cada vez mais conectadas aos seus provedores de serviços para ter acesso de forma automática a produtos e serviços que, em breve, estarão disponíveis.
    Nesse trabalho é proposta a utilização de um computador do tipo placa única (single board computer) para desempenhar as funções de controle primário em um sistema simples de automação residencial para controle de iluminação, que utiliza duas tecnologias diferentes de comunicação sem fio. Será criada uma sintaxe de comandos única para controlar da mesma forma as duas tecnologias de automação residencial. Como contribuição, o trabalho pretende apresentar uma solução de baixo custo, de código aberto e que poderá ser utilizada de forma integrada com a maioria das soluções de automação residencial.

4
  • RODRIGO LOPES BARRETO
  • Contribuições ao Método de Rastreamento da Máxima Potência em Sistemas Fotovoltaico.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • MARCELO CABRAL CAVALCANTI
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • VALENTIN OBAC RODA
  • Data: Jan 22, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • A escassez dos recursos naturais e a busca por fontes de energia alternativa, promovem
    uma rápida mudança na matriz energética mundial. Acredita-se que dentre as fontes de
    energia renováveis a energia solar é a mais promissora. Estudos apontam a energia solar
    como a tecnologia de maior taxa de crescimento na atualidade. Pesquisadores de todo o
    mundo buscam formas de viabilizar seu progresso, desenvolvendo tecnologias com maior
    eficiência e menor custo. Como forma de contribuir ao avanço mundial, neste trabalho
    é proposto o desenvolvimento de uma estratégia de rastreamento da máxima potência,
    baseado no método perturbação e observação, para sistemas fotovoltaicos. A estratégia
    de controle proposta é baseada no balanço de potência ativa do sistema, com número
    reduzido de sensores. Ela tambémpermite que o sistema fotovoltaico atue como regulador
    da qualidade de energia no ponto de conexão, compensando a distorção harmônica das
    correntes da rede e do fator de potência. Resultados de simulação são apresentados para
    validar a estratégia proposta.

5
  • EINSTEIN GOMES DOS SANTOS
  • Arquitetura de Software para Barcos Robóticos

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • RAFAEL VIDAL AROCA
  • ANDERSON ABNER DE SANTANA SOUZA
  • Data: Jan 23, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • O desenvolvimento de uma arquitetura de controle de alto nível para plataformas robóticas aquáticas autônomas destinadas a atuarem em diferentes ambientes aquáticos por longos períodos de tempo apresenta alguns desafios que precisam ser resolvidos, tais como, oferecer condições para se realizar uma navegação da forma mais otimizada possível, tornando esse ponto mais complexo quando a propulsão for oriunda somente da força do vento; dar suporte a telemetria, mesmo a plataforma estando em qualquer lugar a centenas de quilômetros da estação-base; identificar e desviar possíveis obstáculos, previsão de mal tempo e tomada de decisão quanto à segurança da embarcação; fornecer mecanismos para atuarem na remoção de cracas no casco da embarcação que dificultam a sua navegação, além de ser robusta a ponto de evitar o maior número de falhas possível. Caso ocorram, ter a capacidade de contorná-las e devolver a estabilidade ao sistema. Apesar de haver um número considerável de trabalhos publicados acerca do desenvolvimento de plataformas robóticas aquáticas autônomas, bem como, existir competições anuais com o intuito de estimular sua pesquisa, não se tem notícias de travessias oceânicas de embarcações totalmente autônomas, para por em prova a sua robustez. Diante disso, a partir do projeto N-Boat do Laboratório Natalnet do Departamento de Computação e Automação (DCA) da UFRN, que tem como objetivo capacitar um veleiro a navegar de forma autônoma e trocar dados com uma estação-base em qualquer ponto, no qual esteja atuando, pretende-se com esse estudo tornar viável o desenvolvimento dessas plataformas mais robustas e confiáveis quanto à navegação, telemetria e capacidade de operação por longos períodos de tempo, sem a intervenção do homem.

6
  • GASPAR FONTINELI DANTAS JÚNIOR
  • CONTROLE PREDITIVO NÃO-LINEAR APLICADO AO CONTROLE DE GOLFADAS EM PROCESSOS DE PRODUÇÃO DE PETRÓLEO

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • ANDRE LAURINDO MAITELLI
  • OSCAR GABRIEL FILHO
  • Data: Jan 23, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • A golfada é um regime instável do fluxo multifásico, com oscilações de pressão e vazão abruptas no processo de produção de petróleo, podendo ocasionar problemas tais como vibração no encanamento e alto nível de líquido nos separadores.  Pode ser classificada de acordo com seu local de ocorrência.  A mais severa destas, conhecida como golfada no riser, ocorre na tubulação vertical que alimenta a plataforma. Conhecida também como golfada severa, ela é capaz de causar bruscas oscilações na pressão, nas vazões do processo, vibração excessiva, inundação dos tanques separadores, produção limitada, parada não programada da plataforma, entre outros aspectos negativos que motivaram a produção deste trabalho.

    Uma solução viável para lidar com tal problema seria projetar um método efetivo para a remoção ou diminuição do regime, como um controlador. De acordo com a literatura, o controlador convencional PID não apresenta bons resultados devido ao alto grau de não linearidade do processo, o que impulsionou o desenvolvimento de técnicas avançadas de controle.  Dentre estas, o controlador preditivo, cuja ação de controle resulta da solução de um problema de otimização, além de ser uma técnica que apresenta robustez e pode incorporar restrições físicas e/ou de segurança.

    O objetivo deste trabalho é estudar a aplicação de uma técnica de controle preditivo não linear ao controle de golfada severa, visando controlar a quantidade de massa líquida no riser enquanto atuando na válvula de produção e, indiretamente, suprimir as oscilações de vazão e pressão, com fins de obter benefícios ambientais e econômicos. A técnica de controle preditivo proposta baseia-se no uso de aproximações lineares do modelo e na resolução repetida de um problema de otimização quadrática que proporciona soluções que melhoram a cada iteração. No caso em que a convergência desse algoritmo é satisfeita, os valores preditos das variáveis do processo são iguais àqueles que seriam obtidos pelo modelo não-linear original, garantindo que restrições nessas variáveis sejam satisfeitas ao longo do horizonte de predição. Um modelo matemático publicado recentemente na literatura, capaz de representar características da golfada severa em um poço real, é utilizado tanto para a simulação, quanto para projeto do controlador proposto, cujo desempenho é comparado ao de um controlador preditivo linear.

7
  • JOSE ROMULO VIEIRA LIRA
  • Desenvolvimento de um Rastreador Solar do Tipo Polar com Ajuste do Ângulo de Inclinação.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • FRANCISCO DE ASSIS DOS SANTOS NEVES
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Jan 23, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • O aproveitamento da energia solar para geração de energia elétrica tem apresentado
    um crescente interesse nos últimos anos. Nestes sistemas, a conversão de energia solar
    em elétrica é realizada por módulos fotovoltaicos, instalados em estruturas fixas, com
    inclinação determinada em função da latitude do local de instalação. O uso de estruturas
    móveis, com rastreamento solar, tem possibilitado o incremento da produção da energia
    gerada. Neste trabalho, é apresentada a proposta de construção de um rastreador solar,
    que será desenvolvido no Laboratório de Eletrônica de Potência e Energias Renováveis,
    localizado na UFRN. O rastreador proposto é do tipo polar, com rastreamento diário no
    sentido leste-oeste e ajuste do ângulo de inclinação manual nos períodos sazonais, no
    sentido norte-sul. O projeto do rastreador consiste no desenvolvimento de uma estrutura
    mecânica dotada de um sistema de controle de posição. A comprovação do aumento da
    energia produzida é obtida a partir da comparação dos resultados obtidos na estrutura
    rastreada, frente a uma fixa equivalente.

8
  • RAFAELLA CRISTIANNE ALVES DO NASCIMENTO
  • Localização de Robôs Móveis em Ambientes Fechados em Tempo Real Utilizando Câmeras Montadas no Teto

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • ROSIERY DA SILVA MAIA
  • Data: Jan 23, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Propomos um sistema de localização de robôs móveis em ambientes fechados utilizando a técnica de visão global. Uma aplicação pode ser em museus virtuais, que podem ser acessados por usuários do mundo inteiro, usando um avatar robótico, possibilitando ainda a esses mesmos usuários a oportunidade de estabelecer uma presença virtual dentro do museu real, a através de uma plataforma robótica móvel colocada dentro do espaço físico real, permitindo a esse usuário locomover-se virtualmente dentro do museu real. O sistema aqui proposto visa melhorar o processo de localização desse guia robótico dentro do ambiente interno, já que os sensores instalados no mesmo acumulam erros, sem contar o fato de que as constantes mudanças ocorridas nesse tipo de ambiente acaba muitas vezes por introduzir ainda mais erros, ou mesmo até invalidar os dados obtidos devido a um total bloqueio de um determinado sensor. Por ser um método de localização que só leva em considerações informações do momento atual, a localização de robôs através de imagens adequa-se bem a esse tipo de ambiente. Além disso ela proporciona também resultados mais acurados em tempo real.

9
  • DEMÉTRIOS ARAÚJO MAGALHÃES COUTINHO
  • Implementação Paralela Escalável e Eficiente do Algoritmo Simplex Padrão na Arquitetura Multicore

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • DANNIEL CAVALCANTE LOPES
  • JORGE DANTAS DE MELO
  • SAMUEL XAVIER DE SOUZA
  • Data: Jan 24, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho apresenta uma implementação paralela escalável e eficiente do algoritmo simplex padrão na arquitetura de processadores multicore para resolver problemas de programação linear de grande escala. Apresenta-se um esquema geral explicando como foi paralelizado cada passo do algoritmo simplex padrão apontando pontos importantes da implementação paralela. A paralelização proposta é apresentada com destaque para os conceitos de paralelismo utilizados. Foram realizadas análises de desempenho, através da comparação dos tempos sequenciais utilizando o Simplex tableau e Simplex do CPLEX R da IBM . A análise de escalabilidade foi feita com problemas de diferentes dimensões, encontrando evidências de que o algoritmo simplex padrão tem melhor eficiência paralela para problemas com mais variáveis do que restrições. Para apoiar essas afirmações, este trabalho apresenta resultados de vários experimentos numa máquina de memória compartilhada com 24 núcleos.

10
  • RIVALDO RODRIGUES MACHADO JUNIOR
  • Desenvolvimento de um middleware para comunicação via web services e sua aplicação em sistemas de aquisição de dados industriais

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • DIEGO RODRIGO CABRAL SILVA
  • FERNANDO MENEZES MATOS
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Jan 24, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • O controle de processos industriais têm se tornado cada vez mais complexo devido à diversidade de equipamentos de chão-de-fábrica, exigência na qualidade e concorrência de mercado. Tal complexidade exige que, uma grande quantidade de dados seja tratada pelos três níveis de controle de processo: dispositivos de campo, sistemas de controle e software para gerenciamento. Utilizar de forma efetiva os dados presentes em cada um desses níveis é de fundamental importância para indústria.

    Muitos dos sistemas computacionais industriais de hoje são compostos de sistemas distribuídos de software, escritos em uma grande variedade de linguagens de programa- ção e desenvolvidos para plataformas especificas. Desta forma, cada vez mais, pequenas e grandes empresas aplicam um investimento significativo para manter ou até mesmo re- escrever seus sistemas para diferentes plataformas. Além disso, é raro que um sistema de software seja executado em completo isolamento. Na área de automação industrial é comum que sistemas de software interajam com outros sistemas em diferentes máquinas e até mesmo escritos em diferentes linguagens. Tendo isto em vista, interoperabilidade não é apenas um desafio a longo prazo, mas também uma exigência do contexto atual de produção de software industriais.

    Este trabalho visa propor uma solução de middleware para comunicação de aplica- ções via web service, além de apresentar um estudo de caso aplicando a solução desen- volvida a um sistema integrado para captura de dados industriais, permitindo assim que tais dados sejam disponibilizados de maneira simplificada e independente de plataforma através da rede.

11
  • THIAGO DE OLIVEIRA ALVES ROCHA
  • Estratégia de Controle Robusto para interconexão de Sistemas PV Trifásicos à Rede
    Elétrica.

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FLAVIO BEZERRA COSTA
  • ALEXANDRE CUNHA OLIVEIRA
  • LEONARDO RODRIGUES LIMONGI
  • Data: Jan 24, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Atualmente há uma grande preocupação em relação a substituição das fontes não
    renováveis pelas fontes renováveis na geração de energia elétrica. Isto ocorre devido a
    limitação do modelo tradicional e da crescente demanda. Com o desenvolvimento dos
    conversores de potência e a eficácia dos esquemas de controle, as fontes renováveis têm
    sido interligadas na rede elétrica, em um modelo de geração distribuída. Neste sentido,
    este trabalho apresenta uma estratégia de controle não convencional, com a utilização de
    um controlador robusto, para a interconexão de sistemas fotovoltaicos com à rede elétrica
    trifásica. A compensação da qualidade de energia no ponto de acoplamento comum
    (PAC) é realizada pela estratégia proposta. As técnicas tradicionais utilizam detecção de
    harmônicos, já neste trabalho o controle das correntes é feita de uma forma indireta sem a
    necessidade desta detecção. Na estratégia indireta é de grande importância que o controle
    da tensão do barramento CC seja efetuado de uma forma que não haja grandes flutuações,
    e que a banda passante do controlador em regime permanente seja baixa para que as
    correntes da rede não tenham um alto THD. Por este motivo é utilizado um controlador
    em modo dual DSM-PI, que durante o transitório se comporta como um controlador em
    modo deslizante SM-PI, e em regime se comporta como um PI convencional. A corrente
    é alinhada ao ângulo de fase do vetor tensão da rede elétrica, obtido a partir do uso de
    um PLL. Esta aproximação permite regular o fluxo de potência ativa, juntamente com
    a compensação dos harmônicos e também promover a correção do fator de potência no
    ponto de acoplamento comum. Para o controle das correntes é usado um controlador dupla
    sequencia, que utiliza o princípio do modelo interno. Resultados de simulação são
    apresentados para demonstrar a eficácia do sistema de controle proposto.

12
  • LEONARDO VALE DE ARAUJO
  • Anemômetro Baseado em Sensor Termorresistivo com Controle de Temperatura Utilizando Linearização por Realimentação

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • CARLOS EDUARDO TRABUCO DOREA
  • VALENTIN OBAC RODA
  • RAIMUNDO CARLOS SILVÉRIO FREIRE
  • Data: Jan 24, 2014


  • Show Abstract
  • Neste trabalho propõe-se uma nova arquitetura de um anemômetro a fio quente com controle de temperatura através de uma linearização por realimentação da tensão, para um sensor termorresistivo. Um estudo sobre o comportamento do sensor é apresentado, onde o foco está na equação característica, na equação de balanço de energia e no comportamento do sensor em malha aberta. Apresenta-se o modelo do sensor desenvolvido através do Simulink e a arquitetura WB-CTA desenvolvida com o intuito de realizar uma comparação com a arquitetura proposta. A arquitetura proposta nesse trabalho tem como principal objetivo linearizar a relação entrada/saída do sensor e com isso aplicar técnicas de controle convencionais para obter um erro em regime permanente nulo e reduzir o tempo de resposta do sistema. Para este trabalho os resultados das simulações são apresentados e discutidos.

13
  • LUIZ HENRIQUE RODRIGUES DA SILVA
  • Desenvolvimento de solução para SLAM utilizando visão de teto

  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • PABLO JAVIER ALSINA
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • ANDRE MACEDO SANTANA
  • Data: Jan 24, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho visa mostrar uma abordagem pouco explorada do problema de mapeamento e
    localização simultâneos (SLAM), com fim de mapear um ambiente fechado utilizando uma plataforma
    robótica munida de uma câmera voltada para o teto (ascendente) e de odometria para as rodas.
    As marcas utilizadas nesta abordagem são manchas luminosas causadas pelas luminárias no teto.
    Este trabalho visa desenvolver uma aplicação para o filtro de kalman estendido para o SLAM com um
    modelo de observação desenvolvido. Diversos testes e programas foram desenvolvidos para realização
    do SLAM, são apresentados em detalhes. Como objeto principal do trabalho são apresentados os
    testes de SLAM. O desafio reside na convergência do mapa construído pelo robô.
14
  • ANDRÉ TAVARES DA SILVA
  • Controle de posição com restrição à orientação de um Veículo Aéreo Não-Tripulado tipo Quadrirrotor

  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • PABLO JAVIER ALSINA
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • ANDERSON ABNER DE SANTANA SOUZA
  • Data: Jan 24, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Quadrirrotores são veículos aéreos compostos por quatro hélices montadas sobre quatro
    motores em uma disposição em cruz ou x, sendo que, nessa estrutura, os motores
    sobre o mesmo braço giram no mesmo sentido e os do outro braço em sentido oposto.
    Ao girar,cada hélice gera empuxo vertical para cima. O controle é feito variando-se a
    velocidade de rotação de cada motor. Dentre as vantagens desse tipo de veículo pode-se
    citar a simplicidade mecânica de construção, o alto grau de manobrabilidade que possui e
    a capacidade de pousos e decolagens verticais.

    A modelagem e o controle de quadrirrotores tem sido um desafio devido a problemas
    como não-linearidades e acoplamento entre variáveis. Várias estratégias já foram desenvolvidas
    para o controle desse tipo de veículo, desde as de controle clássico como as mais
    modernas.

    Há aplicações de supervisão aérea em que uma câmera é fixada no veículo de forma
    a apontar para a frente, onde é desejado que o quadrirrotor procure se movimentar a
    uma altitude fixa em direção ao alvo também apontando para a frente, o que impõe uma
    restrição artificial de movimento, pois não é desejado que se movimente lateralmente, mas
    apenas para frente ou para trás. Tal restrição é semelhante àquela existente de maneira
    natural em robôs movidos a rodas com acionamento diferencial, que também não podem
    se movimentar lateralmente, mas devido ao atrito das rodas. Portanto, uma estratégia de
    controle de posição semelhante à usada nesse tipo de robôs poderia ser adaptada para
    robôs aéreos do tipo quadrirrotor.

    Este trabalho apresenta e discute algumas estratégias de controle de posição e orientação
    de quadrirrotores encontradas na literatura e propõe uma estratégia baseada no
    controle dinâmico de robôs móveis com acionamento diferencial, o chamado controle por
    referência variável. A validade da estratégia proposta é comprovada através de simulações
    computacionais.

15
  • TALIS LINCOLN FONSECA BARBALHO
  • Um estudo e análise do teste de emissões otoacústicas realizadas através de uma plataforma móvel
  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • FABIANA CRISTINA MENDONCA DE ARAUJO
  • HELIANA BEZERRA SOARES
  • CICILIA RAQUEL MAIA LEITE
  • Data: Jan 27, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Até meados da década de 70, acreditava-se que a orelha era um orgão
    passivo, por receber o sinal sonoro e o transformar em impulsos nervosos, para
    então serem enviados ao cérebro. Entretanto, David T. Kemp, descobriu em 1977,
    através de um microfone amplificador, que existiam tons e ecos sendo emitidos
    de dentro da orelha, esses sons foram então chamados de emissões otoacústicas.
    Com o passar dos anos e o avanço tecnólogico, foram realizados mais testes com
    diferentes pessoas e foi identificado que a presença dos mesmos estavam
    diretamente ligados a saúde auditiva humana, enquanto que a ausência dos sinais
    só acontecem em orelhas com algum problema.
     
    Então foi criado o Exame de Emissões Otoacústicas para que pudesse ser
    realizado logo nos primeiros dias de vida da criança, ou até no máximo com 6
    meses de vida, pois determinados problemas se não forem superados podem
    causar danos neurológicos permanentes nessa área da audição. Devido a
    importância do exame na prevenção de doenças auditivas, este exame tornou-se
    obrigatório em todo território nacional em 2010, através da Lei 12.303/10.
     
    Depois que a Lei foi aprovada no Brasil, foi necessário a compra de muitos
    equipamentos para tornar possível a realização do exame nas grandes
    maternidades públicas do país, mas o aparelho custa entre R$ 20.000,00
    e R$ 30.000,00 reais.
     
    Contudo, este trabalho está inserido ao projeto otoleitor, aprovado no edital
    FINEP de tecnologia assistiva de 2010. O projeto propõe a realização do teste de
    emissões otoacústicas via uma plataforma móvel, ou seja, um celular. O nosso
    trabalho se insere neste contexto na medida que realizamos um estudo sobre os
    tipos de emissões otoacústicas, geração dos sinais adequados e depois uma
    análise das respostas  dos sinais obtidos que serão disponibilizados para equipe
    médica.
16
  • LUCAS COSTA PEREIRA CAVALCANTE
  •  Avaliação de Desempenho da Codificação Wavelet em Canais Seletivos em Frequência

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • MARCELO AUGUSTO COSTA FERNANDES
  • LUIZ GONZAGA DE QUEIROZ SILVEIRA JUNIOR
  • ERNESTO LEITE PINTO
  • Data: Feb 14, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • A codificação wavelet surgiu como uma técnica de codificação de canal alternativa para minimizar os efeitos destrutivos dos canais de comunicação sem fio caracterizados pelo desvanecimento. Diferente de técnicas clássicas de codificação, nas quais o ganho de codificação surge através da adição de uma redundância controlada a informação, a robustez conseguida pela codificação wavelet contra os efeitos do desvanecimento ocorre em função de uma diversidade temporal gerada sobre a informação transmitida. Até o momento, o desempenho da codificação wavelet foi investigado apenas em canais de comunicação sujeito a desvanecimento plano variante no tempo. Este trabalho avalia o desempenho da codificação wavelet, em termos de probabilidade de erro de bit, sobre canais de comunicação com desvanecimento Rayleigh variante no tempo e seletivo em frequência. Através de simulação computacional, apresenta-se nesse trabalho resultados numéricos que demonstram a eficiência dessa técnica no combate à interferência inter-simbólica, característica destes cenários de comunicação.

17
  • TIAGO FERNANDO BARBOSA DE SOUSA
  • Equalização Neural Aplicada a Sistemas com Modulação Bidimensional em Fibra Óptica

  • Advisor : MARCELO AUGUSTO COSTA FERNANDES
  • COMMITTEE MEMBERS :
  • MARCELO AUGUSTO COSTA FERNANDES
  • ADRIAO DUARTE DORIA NETO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • SILVIO JOSE BEZERRA
  • VICENTE IDALBERTO BECERRA SABLON
  • Data: Feb 28, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • A fibra óptica é um dos meios de comunicação mais utilizados atualmente, principalmente devido ao fato da taxa de transmissão de dados desses sistemas excederem as de todos os outros meios de comunicação digital. Apesar da grande vantagem, existem problemas que impedem o total aproveitamento do canal  óptico: com o aumento da velocidade de transmissão e das distâncias envolvidas, os dados ficam sujeitos a interferência intersimbólica não-linear, causadas pelos fenômenos de dispersão na fibra. Para solucionar esse problema podem ser utilizados equalizadores adaptativos, que compensam respostas não ideais do canal, com o intuito de restaurar o sinal que foi transmitido. Neste trabalho é feito o estudo de uma proposta baseada em redes neurais artificiais, um equalizador neural aplicado a sistemas de comunicação óptica. A proposta é validada através de um canal óptico simulado e é feita a comparação com outras técnicas de equalização adaptativa.

18
  • JAN'' ERIK MONT'' GOMERY PINTO
  • Aplicação Prática de Método de Sintonia de Controladores PID Utilizando o Método do Relé com Histerese

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • OSCAR GABRIEL FILHO
  • VICENTE DELGADO MOREIRA
  • Data: May 16, 2014


  • Show Abstract
  • Os campos de pesquisa e desenvolvimento de softwares envolvendo a sintonia PID de controladores, ainda é uma área ativa dentro do meio acadêmico e industrial. Tudo isso devido à larga utilização de controladores PID na indústria (96% de todos os controladores na indústria ainda é PID). Ter controladores bem sintonizados e com ferramentas que possam acompanhar seus desempenhos ao longo do tempo com a possibilidade de ressintonizá-los, ou ainda auto-sintonizá-los, passar a ser um item quase que obrigatório para manter processos com alta produtividade e baixo custo. Já que em um mundo globalizado, o nível mais acirrado de concorrência entre as empresas, atualmente, está no custeio e na produtividade. Apesar de existirem diversas novas técnicas e ferramentas que fazem sintonia PID, neste trabalho exploraremos a sintonia PID utilizando o método do relé, devido a sua boa aceitação no ambiente industrial. Além disto, abordaremos algumas técnicas de avaliação de malhas de controle, tais como IAE, ISE, Goodhart, variância do sinal de controle e índice de Harris, pois são necessários para sugerir novas sintonias PID para as malhas de controle com baixo desempenho. Será proposto neste trabalho uma ferramenta de sintonia e auto-sintonia PID (usando o método do relé), bem como um ferramenta para avaliação de malhas de controle de uma forma mais prática. Em especial, será destacado o método do relé com histerese. Este método tem apresentado sintonias com desempenhos satisfatórios quando aplicados às plantas didáticas, simuladas e real.

19
  • RODRIGO PRADO DE MEDEIROS
  • Proteção Diferencial de Transformadores de Potência Utilizando a Transformada Wavelet

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • FLAVIO BEZERRA COSTA
  • KLEBER MELO E SILVA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • Data: May 26, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Cerca de 10% das faltas envolvendo o sistema elétrico ocorrem em transformadores de potência. Portanto, a proteção aplicada aos transformadores de potência é essencial para garantir o funcionamento contínuo desse dispositivo e a eficiência do sistema elétrico. Dentre as funções de proteção aplicadas em transformadores, a proteção diferencial aparece como um dos principais esquemas, apresentando confiável discriminação entre faltas internas e faltas externas ou condições de carregamento nominal do sistema. Porém, a principal dificuldade dos métodos de proteção convencional consiste na demora para detecção dos eventos. Contudo, faltas internas, faltas externas e os demais eventos apresentam transitórios, podendo ser apropriadamente analisados pela transformada wavelet. Neste trabalho é proposto o desenvolvimento de um esquema de proteção diferencial de transformadores baseado na transformada wavelet para detecção e identificação de faltas externas, faltas internas e energização do transformador usando a energia dos coeficientes wavelets das correntes diferenciais. Os resultados revelam as vantagens da utilização da transformada wavelet na proteção diferencial em relação à proteção convencional, uma vez que ela provê confiabilidade e rapidez na detecção desses eventos.

20
  • FILIPE EMANUEL VIEIRA TAVEIROS
  • Sistema de Conversão de Energia Eólica Baseado no Gerador de Indução Duplamente Alimentado: Análise e Contribuição ao Controle da Máquina

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • FLAVIO BEZERRA COSTA
  • FRANCISCO KLEBER DE ARAÚJO LIMA
  • JOSSANA MARIA DE SOUZA FERREIRA
  • LUCIANO SALES BARROS
  • Data: May 28, 2014


  • Show Abstract
  • A humanidade encontra-se numa época de desenvolvimento tecnológico sem precedentes.
    A ciência alcançou e continua alcançando conquistas que permitem compreender cada vez mais o universo e as leis que o regem e, também, tentar coexistir sem destruir o planeta em que vivemos. Um dos principais desafios do século XXI é buscar e incrementar a gama de fontes de energias limpas, renováveis e capazes de sustentar nosso crescimento e estilo de vida. É dever de cada pesquisador dedicar-se e contribuir nesta corrida energética. Neste contexto, a energia eólica se apresenta como uma das grandes promessas para o futuro da geração elétrica. Apesar de ser um pouco mais antiga que outras fontes de energia renovável, a geração eólica ainda apresenta um vasto campo para melhoramento. O desenvolvimento de novas técnicas de controle do gerador juntamente com o desenvolvimento de laboratórios de pesquisa especializados em geração eólica formam um dos pontos chave para aumentar o rendimento, a eficiência e a confiabilidade do sistema. O controle apropriado do esquema de conversores back-to-back permite que as turbinas eólicas baseadas no gerador de indução duplamente alimentado (DFIG) operem no modo de velocidade variável, cujos benefícios incluem máxima extração de potência, injeção de potência reativa e redução de estresse mecânico. O conversor do lado do rotor fornece controle de potência ativa e reativa injetada na rede, enquanto que o conversor do lado da rede fornece o controle da tensão no link CC e fluxo de potência bi-direcional. A estrutura de controle convencional utiliza controladores PI com compensação feed-forward dos termos de acoplamento cruzado. Como desvantagens, esta técnica de controle apresenta sensibilidade a incertezas do modelo e, também, a compensação de termos dinâmicos acoplados resulta em uma estratégia de controle concorrente. Por isso, para superar estes problemas e eliminar os termos de acoplamento cruzado, é utilizado uma estrutura de controle robusta com realimentação de estados baseada no princípio do modelo interno,
    visando melhorar o acionamento do gerador bem como o seu comportamento dinâmico durante variações abruptas na velocidade do vento. O desempenho da técnica de controle proposta para o controle do gerador DFIG será comparado ao da abordagem de controle convencional sob condições de vento estáveis e rajadas. Um emulador de turbina eólica foi desenvolvido para recriar em laboratório uma condição realista e submeter o gerador a várias condições de velocidade do vento.

21
  • FRANCISCO CARLOS GURGEL DA SILVA SEGUNDO
  • Análise e Projeto de Superfícies Seletivas em Frequência Multibanda e Banda Larga

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JOSE PATROCINIO DA SILVA
  • RONALDO DE ANDRADE MARTINS
  • Data: Jun 5, 2014


  • Show Abstract
  • Superfícies seletivas em frequência (Frequency Selective Surface - FSS) são usadas frequentemente em diversas aplicações em telecomunicações. Algumas dessas aplicações podem exigir que essas estruturas tenham resposta com múltiplas bandas de ressonância. Outras aplicações exigem que as FSS tenham resposta em frequência larga, para atender aos requisitos necessários. Para projetar FSS com essas características existem inúmeras técnicas usadas na literatura. Assim, o propósito deste trabalho é analisar algumas técnicas utilizadas e projetar FSS multibanda e/ou banda larga selecionando técnicas simples em termos de construção e que ocupem o menor espaço possível, visando aplicações práticas.

22
  • TIAGO DOS SANTOS BEZERRA
  • Predição de Séries Temporais de Parâmetros em Redes HSPA – WCDMA

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JEFFERSON COSTA E SILVA
  • VICENTE ANGELO DE SOUSA JUNIOR
  • Data: Jun 10, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Com o crescimento das demandas de tráfego de dados em redes de terceira geração (3G), as operadoras de telefonia móvel têm atentado para o direcionamento dos recursos em infraestrutura nos locais onde se identifica maior necessidade. Estes locais geralmente são os grandes centros urbanos com maior densidade de usuários da rede. O direcionamento desses investimentos tem o objetivo de manter a qualidade do serviço prestado nestas regiões. Esse trabalho apresenta uma proposta para predição de séries temporais em rede HSPA – WCDMA dos parâmetros CQI (Channel Quality Indicator), Ec/Io (Energy per chip/Interference), a taxa de retransmissão e a taxa de transmissão (throughput) na camada física. A coleta dos valores dos parâmetros da rede em pleno funcionamento foi realizada através um drive tests em área predefinida numa capital brasileira. Os modelos sugeridos para predição das séries temporais foram os de Autoregressão, Método de Alisamento Exponencial Adaptativo Trigg and Leach e ARIMA (Autoregressive Integrated Moving Average). Com a realização das predições das séries temporais será efetuada uma análise comparativa para identificação do modelo mais adequado para cada parâmetro.

23
  • ARTHUR DIEGO DE LIRA LIMA
  • Arquiteturas Eficientes para Sensoriamento Espectral e Classificação Automática de Modulações Usando Características Cicloestacionárias

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ALLAN DE MEDEIROS MARTINS
  • MARCELO AUGUSTO COSTA FERNANDES
  • EDMAR CANDEIA GURJÃO
  • Data: Jun 28, 2014


  • Show Abstract
  • Técnicas que exploram as características cicloestacionárias dos sinais de rádio têm sido largamente investigadas nos últimos anos para aplicações em sensoriamento espectral, sobretudo em ambientes de comunicação com baixa relação sinal-ruído, ou com ruído não-estacionário. Entretanto, as assinaturas cicloestacionárias de sinais modulados também têm sido investigadas, em trabalhos recentes, como medidas de classificação de formatos de modulações. Em particular, uma assinatura cicloestacionária denominada perfil-alfa, obtida como uma projeção da função de Densidade de Correlação Espectral (SCD - Spectral Correlation Density), tem se mostrado promissora na classificação automática de modulações (AMC). Neste trabalho, propomos o uso do perfil-alfa reduzido, obtido por uma aproximação do perfil-alfa de sinais modulados, como medida para uma estratégia de classificação de modulações por correlação. Adicionalmente, utilizamos uma Rede Neural Artificial do tipo Multilayer Perceptron para avaliar a qualidade do classificador. O desempenho da técnica de classificação baseada em perfil-alfa reduzido e correlação foi avaliado por simulação computacional em um ambiente de comunicação caracterizado pelo ruído aditivo gaussiano branco (AWGN). Os resultados numéricos de desempenho obtidos neste trabalho demonstram a eficiência da técnica proposta.

24
  • DANIEL ENOS CAVALCANTI RODRIGUES DE MACEDO
  • Br-IndustrialExpert: um framework para análise de dependabilidade de processos industriais

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • BRUNO SIELLY JALES COSTA
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jul 4, 2014


  • Show Abstract
  •  A demanda por desenvolvimento de novas ferramentas para suporte ao projeto, monitoramento, manutenção e comissionamento de processos industriais é permanente. A complexidade do ambiente industrial exige que estas ferramentas sejam flexíveis para fornecer dados valiosos no planejamento inicial e na frase de projeto. Mais que isso, é conhecido que processos industriais têm requisitos rigorosos para dependabilidade (confiabilidade e disponibilidade), desde que falhas podem causar perda econômica, danos ambientais e por pessoas em risco. Assim, esse trabalho apresenta uma ferramenta que é capaz de estimar a dependabilidade de processos industriais modelados como um grafo. A ferramenta transforma uma estrutura de grafo (representando o processo industrial) em um modelo de Árvore de Falhas para analisar a dependabilidade do processo. Estudos da dependabilidade de diferentes processos são conduzidos para validar a proposta.

25
  • ERNANO ARRAIS JUNIOR
  • Estratégia de Conversor para Interligação de Sistemas de Geração Eólica à Rede Elétrica

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • VALENTIN OBAC RODA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • FRANCISCO DE ASSIS DOS SANTOS NEVES
  • Data: Jul 11, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Existem diversas topologias de conversores de potência aplicadas a sistemas de geração de energia eólica. Os conversores permitem a geração de energia com turbinas eólicas em condições de velocidade variável do vento, possibilitando um aproveitamento de forma mais eficaz das forças do vento. A utilização dos conversores possibilita o controle efetivo da potência injetada na rede, seja de maneira parcial, no caso de utilização de conversores parciais, ou controle total, no caso de utilização de conversores completos. O alto desempenho dos conversores vem sendo cada vez mais necessário, principalmente quando se busca a elevação da capacidade de geração de potência por parte das turbinas eólicas, o que fez surgir diversas novas topologias de conversores, sejam conversores paralelos ou multiníveis. O conversor na configuração back-to-back é um dos mais utilizados no mercado atualmente, devido à sua estrutura simples, com poucos componentes, contribuindo assim para um desempenho robusto e confiável. Neste trabalho, propõe-se a implementação de um sistema de cogeração eólica utilizando um gerador síncrono a ímã permanente (PMSG) associado a um conversor de potência na topologia back-to-back, de maneira a injetar potência ativa em um sistema elétrico de potência. A estratégia do controle da potência ativa fornecida pela cogeração à rede elétrica é baseada na filosofia do controle indireto.

26
  • DIEGO VINICIUS CIRILO DO NASCIMENTO
  • Implementação em FPGA de módulo de efeito de reverberação

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • EMERSON CARLOS PEDRINO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • VALENTIN OBAC RODA
  • Data: Aug 4, 2014


  • Show Abstract
  • O efeito de reverberação ocorre pela reflexão do som nas superfícies adjacentes à fonte
    sonora durante sua propagação até o ouvinte e a resposta ao impulso de um ambiente
    representa suas características de reverberação. Por ser dependente do ambiente, a reverberação
    leva ao ouvinte características do espaço onde o som está sendo reproduzido e
    comumente sua ausência não soa como “natural”. Como nem sempre é possível ter características
    desejáveis de reverberação em gravações, métodos para reverberação artificial vêm
    sendo desenvolvidos há décadas, sempre buscando implementações mais eficientes e mais
    fiéis aos ambientes reais. Neste trabalho é apresentada uma implementação em FPGA
    (Field Programmable Gate Array) de uma estrutura de reverberação digital de áudio clássica,
    usando filtros allpass, baseada na proposta de Manfred Schroeder, demonstrando a
    utilização de hardware reconfigurável como plataforma de desenvolvimento e implementação
    de efeitos digitais de áudio, com foco nas características de modularidade e de reuso.

27
  • SAMUEL DE PAIVA REGO
  • Implementação da infra-estrutura e protocolo de comunicação para tratamento e disponibilização de dados do projeto ePoste

  • Advisor : VALENTIN OBAC RODA
  • COMMITTEE MEMBERS :
  • VALENTIN OBAC RODA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • EMERSON CARLOS PEDRINO
  • Data: Dec 8, 2014


  • Show Abstract
  • O projeto “ePoste” é um sistema de monitoramento por comunicação sem fio que tem
    por objetivo sensorear e atuar em um ou vários pontos de iluminação pública. O presente
    trabalho consistiu na elaboração da estrutura e do protocolo de comunicação do projeto
    ePoste e também o tratamento de dados para detecção de eventos nos sensores localizados
    nos postes. Anteriormente a comunicação com os sensores era local, e quando
    havia a necessidade de coleta de dados ou atuação nestes dispositivos, o operador tinha
    que se deslocar até o alcance da rede local. De posse disso, a proposta tem o interesse
    de aumentar a dinamicidade do sistema, chegando a possíveis integrações com sistemas
    já existentes para gestão de iluminação. É levado em consideração a mesma tecnologia
    de comunicação já existentes entre os sensores, utilizando o protocolo ZigBee operando
    sobre rede mesh, onde a comunicação com essa rede é feita pela internet através de um
    gateway. O protocolo desenvolvido, trata da formação de quadro em nível mais baixo,
    onde se define início, tamanho, e checagem de erros, utilizado na comunicação entre o
    sensor, concentrador e servidor; e também o protocolo de nível mais alto, tratando-se de
    um serviço que utiliza atributos de nomes para atender requisições GET e POST sob o
    protocolo HTTP, implementado no servidor de dados, estando disponível para a comunicação
    com os sistemas clientes, no caso, sistemas de gerenciamento de iluminação.

28
  • CARLOS ANTONIO MENDES DA COSTA JUNIOR
  • Especificações e Projeto de um Front-End UHF Multipadrão Integrado em Tecnologia CMOS 130 nm

  • Advisor : SEBASTIAN YURI CAVALCANTI CATUNDA
  • COMMITTEE MEMBERS :
  • ANTONIO AUGUSTO LISBOA DE SOUZA
  • MARCELO AUGUSTO COSTA FERNANDES
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Dec 10, 2014


  • Show Abstract
  • Atuando na área de microeletrônica, o projeto a ser desenvolvido nesse mestrado pretende melhorar o atual transponder dos satélites pertencentes ao Sistema Brasileiro de Coleta de Dados Ambientais (SBCD), aprimorando sua tecnologia e reduzindo seu consumo de potência e seu tamanho em, no mínimo, uma escala de dez.

    O SBCD é um sistema pertencente ao Programa Espacial Brasileiro e que começou a ser arquitetado ainda no início da década de 90, sendo inicializado com o lançamento bem sucedido do primeiro satélite brasileiro, o Satélite de Coleta de Dados-1, em 1993. O sistema consiste em centenas de Plataformas de Coletas de Dados (PCDs) espalhadas pelo território brasileiro e que têm a função de coletar dados ambientais, tais como temperatura, umidade relativa do ar, velocidade e direção do vento, precipitação de chuva, dentre outros, e enviá-los periodicamente aos satélites brasileiros de baixa orbita terrestre. Esses, por sua vez, retransmitem, a cada passagem sob o nosso território, todos os dados recebidos de centenas de PCDs para as estações terrenas de recepção de Cuiabá e Alcântara, que reenviam os dados para serem processados no Centro de Missão de Coleta de Dados, no INPE-CRN de Natal-RN. Todas as informações adquiridas pelo sistema são distribuídas gratuitamente para importantes usuários, como a Agência de Nacional de Águas (ANA) e a Agência Nacional de Energia Elétrica (ANEEL). O link de subida e decida do sinal são respectivamente 401,625 MHz e 2.267,52 MHz, utilizando uma modulação BPSK modificada para melhorar a detecção do sinal.

    Atualmente o repetidor utilizado nos satélites SCD-1, SCD-2, CBERS-2b e CBERS-3 são construídos com componentes totalmente discretos e quase de forma artesanal. O intuito desse trabalho é assim permitir a integração dos principais componentes do receptor do transponder, gerando mais confiabilidade, mais simplicidade, além da redução do consumo de energia e do tamanho físico do circuito. Além desses objetivos, o projeto virá também com a intenção de validar tecnologias espaciais críticas como a proteção de circuitos integrados contra radiação cósmica.

    O Amplificador de Baixo Ruído (do inglês Low Noise Amplifier - LNA) e o Misturador (do inglês Mixer) serão os componentes a serem integrados no chip. O trabalho será divido em 3 etapas principais, sendo a primeira a análise de literatura e cálculos iniciais dos circuitos, seguidas pelas simulações em ferramentas de design auxiliado por computador (CAD) e pelos testes elétricos do circuito integrado (CI), uma vez que esse for produzido.

    O produto final desse trabalho deverá ser utilizado em todos os futuros satélites do SBCD. Em especial, esse projeto almeja estar presente nos nano-satélites (NS) da constelação ConaSat, projeto do INPE-CRN que pretende consolidar o sistema de coleta de dados brasileiro de forma mais econômica e eficiente que os pequenos satélites hoje utilizados.

29
  • BETOVEN OLIVEIRA DE ANDRADE
  • Estudo de Arranjos de Antenas de Microfita com Patch Quase-fractal para Comunicações Sem Fio

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO
  • JOSE PATROCINIO DA SILVA
  • WELLINGTON CANDEIA DE ARAUJO
  • Data: Dec 11, 2014


  • Show Abstract
  • Nesta dissertação, são apresentadas duas antenas de microfita e dois arranjos para aplicações em sistemas de comunicação sem fio multibanda. Inicialmente, foi estudada uma antena e um arranjo linear constituído por dois elementos idênticos ao da antena isolada. A forma de ambas as estruturas baseia-se na geometria fractal e tem comportamento de banda múltipla. Em seguida uma nova antena é analisada e um novo arranjo igual à estrutura inicial, mas com o plano de terra truncado, a fim de obter melhores larguras de banda e perda de retorno. Para alimentar as estruturas foi utilizada linha de transmissão de microfita. No projeto das estruturas planares utilizou-se o software HFSS para a simulação. Em seguida foram construídas e feitas medições dos parâmetros eletromagnéticos como impedância de entrada e perda de retorno, usando o analisador vetorial de redes do laboratório de telecomunicações da Universidade Federal do Rio Grande do Norte. Os resultados experimentais obtidos foram comparados com os simulados e mostraram que o primeiro arranjo melhorou a perda de retorno, fez surgir uma quarta banda de frequência e aumentou a diretividade em relação à antena isolada. Os dois primeiros benefícios não são comumente encontrados na literatura. Quanto às estruturas com planos de terra truncados, a técnica produziu um melhor casamento de impedância e melhor largura de banda e perda de retorno em todas as bandas de frequência com relação às estruturas iniciais com planos de terra cheios. Além disso, estas estruturas apresentaram uma melhor distribuição das bandas ao longo da faixa, o que pode facilitar um ajuste das mesmas para frequências específicas. Deste modo, espera-se que as estruturas planares apresentadas neste trabalho, em especial os arranjos, possam ser adequadas a aplicações específicas em comunicações sem fio, onde multibandas e sinais banda larga de transmissão são exigidos.

30
  • GUSTAVO FERNANDES DE LIMA
  • Proposta de Tecnologia para Controle de Velocidade de PIGs Instrumentados Utilizando
    Lógica Fuzzy

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • FRANCISCO DE ASSIS OLIVEIRA FONTES
  • OSCAR GABRIEL FILHO
  • Data: Dec 16, 2014


  • Show Abstract
  • O controle de velocidade de PIGs instrumentados é necessário, dentro da indústria de petróleo e gás, para permitir uma inspeção de dutos de melhor qualidade e maior segurança. Isto só é possível quando esses PIGs mantêm uma velocidade baixa durante a operação de inspeção de dutos, na procura de defeitos como corrosão, trincas e amassamentos. Este trabalho tem por objetivo propor uma tecnologia para o controle de velocidade de PIGs instrumentados utilizando uma válvula by-pass acionada por uma solenoide. Essa válvula tem a capacidade de controlar o diferencial de pressão atuante no corpo do PIG. E controlar o diferencial de pressão significa controlar a velocidade desse PIG. Uma bancada de testes foi montada em escala reduzida para simulação de situações de “tiro” e de aceleração sofridos pelos PIGs. A bancada permitiu estudar as reações das pressões a montante e a jusante da válvula by-pass. A lógica Fuzzy foi utilizada para determinar os tempos de abertura e fechamento dessa válvula, com objetivo de controlar o diferencial de pressão. Os testes na bancada mostraram uma redução substancial no valor do diferencial de pressão atuante no PIG após a ocorrência do “tiro”. Também ocorreu uma redução no tempo em que o diferencial de pressão vai ao máximo e retorna ao valor de referência predefinido. Os resultados obtidos permitem concluir que é possível controlar o diferencial de pressão atuante no PIG, assim também a velocidade, utilizando a lógica Fuzzy, atuando na abertura e fechamento da válvula by-pass proposta.

31
  • ALESSANDRO ASSI MARRO
  • Modelo para Reconstrução 3D de Cenas baseado em Imagens

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • ANDERSON ABNER DE SANTANA SOUZA
  • Data: Dec 22, 2014


  • Show Abstract
  • Reconstrução 3D é o processo pelo qual se faz possível a obtenção de um modelo gráfico detalhado em três dimensões de alguma cena objetivada. Este modelo faz uso de sequências de imagens, utilizadas para mapear uma cena, para poder adquirir de forma automatizada informações sobre a profundidade de pontos característicos, ou como comumente chamados features. Esses pontos são portanto destacados utilizando-se alguma técnica computacional sobre as imagens que compõem o dataset utilizado. Utilizando pontos característicos SURF (Speeded-Up Robust Features), restrições de formação de mosaicos de imagens e técnicas de Visão Computacional, este trabalho procura propor um modelo quase completo para obtenção de informações 3D sobre pontos principais detectados pelo sistema. Ao termino da aplicação do sistema proposto sobre sequências de imagens é objetivada a aquisição de três importantes informações: a posição 3D dos pontos característicos; as matrizes de rotação e translação relativas entre as imagens; o estudo que relaciona a baseline entre as imagens adjacentes e o erro de precisão do ponto 3D encontrado. Resultados de implementações são mostrados indicando resultados consistentes. O sistema proposto também segue restrições de Software livre, o que é uma contribuição significativa para esta área de aplicação.

Thesis
1
  • BRUNO GOMES DE ARAUJO
  • C-LPS: Linha de Produtos de Software Baseada em Aspectos para Desenvolvimento e Certificação de Sistemas de Registro Eletrônico de Saúde

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • FILIPE DE OLIVEIRA QUINTAES
  • GLAUCIO BEZERRA BRANDAO
  • HELIO ROBERTO HEKIS
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ROBINSON LUIS DE SOUZA ALVES
  • Data: Jan 20, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • A Certificação de Software está se tornando uma prática comum nos projetos de desenvolvimento de software. Ela permite que sistemas sejam testados e validados, garantindo que estejam em conformidade com os requisitos especificados e critérios estabelecidos, agregando, desta forma, maior qualidade aos produtos finais. O Conselho Federal de Medicina (CFM) em cooperativa com a Sociedade Brasileira de Informática em Saúde (SBIS) já utilizam esta prática, certificando Sistemas de Registro Eletrônico em Saúde (S-RES) antes de serem executados em ambiente hospitalar e na saúde de maneira geral. Devido boa parte do processo de certificação ser realizado de forma manual, acaba se tornando em um processo custoso, além de necessitar de profissionais com conhecimentos específicos para cada tipo de sistema. Visando isto, o presente trabalho tem como objetivo o desenvolvimento de uma ferramenta, chamada de C-LPS, capaz de auxiliar o processo de certificação através de técnicas de Programação Orientada a Aspectos, Teste de Software e OCL. A ferramenta permite a geração de sistemas através do conceito de Linhas de Produtos de Software, incorporando facilmente as regras de certificação estabelecidas, desta forma, automatizando o processo de Certificação do sistema gerado. Como estudo de caso, será utilizado um sistema de Prontuário Eletrônico de Pacientes para validar a ferramenta.

2
  • ÍCARO LINS LEITÃO DA CUNHA
  • Revisitando o Problema de Visibilidade para Visualização Tridimensional

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • RICARDO CORDEIRO DE FARIAS
  • RUMMENIGGE RUDSON DANTAS
  • Data: Jan 22, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Nós revisitamos o problema de visibilidade, que visa determinar um conjunto de primitivas potencialmente visíveis em um conjunto de dados gemétricos representados por uma estrutura de dados, por exemplo uma malha de polígonos ou de triângulos, propondo uma solução para acelerar o processamento em aplicações em visualização tridimensional. Introduzimos uma estrutura enxuta, no sentido de abstração e redução de dados, que pode ser usada para aplicações on-line e interativas. O problema de visibilidade é especialmente importante na visualização 3D de cenas representadas por grande volume de dados, em que não é interessante manter todos os polígonos da cena em memória, pois implicaria em um maior tempo gasto na renderização, ou sendo até mesmo impossível mantê-los todos em volumes imensos de dados. 
    Nestes casos, dada uma posição e uma direção de visualização, o objetivo principal é determinar e carregar o mínimo possível de primitivas (polígonos) da cena, visando acelerar a etapa de renderização. Para este propósito, nosso algoritmo executa o corte de primitivas (culling) usando um paradigma híbrido baseado em dois modelos conhecidos. A cena é subdividida em células de uma grade, sendo associada a cada uma dessas células as primitivas pertencentes a elas, e finalmente determinado o conjunto de primitivas potencialmente visíveis. A novidade é o uso da triangulação J1 para criar a subdivisão em grade. Escolhemos esta estrutura devido às suas características relevantes de adaptatividade e algebrismo (facilidade de cálculos). Os resultados mostram uma melhoria substancial sobre os métodos tradicionais quando aplicados separadamente. O método introduzido neste trabalho pode ser usado em dispositivos sem processador dedicado ou com baixo poder de processamento, como telefones celulares ou dispositivos com display embarcado ou ainda para visualizar dados através da Internet, tal como em aplicações de museus virtuais.

3
  • MARCELO RIBEIRO DA SILVA
  • Otimização de Superfícies Seletivas de Frequência com Elementos Pré-Fractais Utilizando Rede Neural MLP e Algoritmos de Busca Populacional


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • HERTZ WILTON DE CASTRO LINS
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • MARCOS TAVARES DE MELO
  • Data: Jan 27, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Esta tese propõe metodologias de projeto para superfícies seletivas de frequência (FSSs) compostas por arranjos periódicos de patches metálicos pré-fractais impressos em camadas dielétricas simples (FR4, RT/duroid). As formas apresentadas pelas geometrias correspondentes à ilha de Sierpinski e ao fractal T são exploradas para o projeto simples de filtros espaciais rejeita-faixa eficientes com aplicações na faixa de micro-ondas. Resultados iniciais são discutidos em termos do efeito eletromagnético decorrente da variação de parâmetros como, número de iterações fractais (ou nível do fractal), fator de iteração fractal, e periodicidade da FSS, dependendo do elemento pré-fractal utilizado (ilha de Sierpinski ou fractal T). As propriedades de transmissão destes arranjos periódicos propostos são investigadas através de simulações realizadas pelos programas comerciais Ansoft DesignerTM e Ansoft HFSSTM, que executam métodos de onda completa. Para validar a metodologia empregada, protótipos de FSS são selecionados para fabricação e medição. Os resultados obtidos apontam características interessantes para filtros espaciais de FSS, tais como: estrutura compacta, com maiores fatores de compressão de frequência; além de respostas estáveis em frequência com relação à incidência oblíqua de ondas planas. Esta tese aborda ainda, como enfoque principal, a aplicação de uma técnica alternativa de otimização eletromagnética (EM) para análise e síntese de FSSs com motivos fractais. Em exemplos de aplicação desta técnica, elementos pré-fractais de Vicsek e Sierpinski são usados no projeto ótimo das estruturas de FSS. Baseada em ferramentas de inteligência computacional, a técnica proposta supera o alto custo computacional proveniente das análises paramétricas de onda completa. Para este fim, são desenvolvidos modelos rápidos e precisos de rede neural do tipo perceptron de múltiplas camadas (MLP) utilizando diferentes parâmetros como variáveis de entrada do projeto. Estes modelos de rede neural têm como objetivo calcular a função custo nas iterações dos algoritmos de busca populacional. O algoritmo genético contínuo (GA), a otimização por enxame de partículas (PSO), e o algoritmo das abelhas (BA), são usados para a otimização das FSSs com valores específicos de frequência de ressonância e largura de banda. O desempenho destes algoritmos é comparado em termos do custo computacional e da convergência numérica.  Resultados consistentes podem ser verificados através da excelente concordância obtida entre simulações e medições referentes aos protótipos de FSS construídos com uma dada iteração fractal.

4
  • LEONARDO MARTINS CAETANO
  • Materiais Supercondutores HTS para Arranjos de Antenas e Aplicação de PBG para Micro-ondas

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUGO MICHEL CAMARA DE AZEVEDO MAIA
  • HUMBERTO CESAR CHAVES FERNANDES
  • HUMBERTO DIONISIO DE ANDRADE
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOSE PATROCINIO DA SILVA
  • RONALDO DE ANDRADE MARTINS
  • Data: Jan 27, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Atualmente as antenas de microfita lineares e planares têm despertado interesses devido as suas características e vantagens que oferecem quando comparadas com os demais tipos de antenas. Na área de comunicações sem fio à necessidade de antenas desse tipo, tem se tornado cada vez mais utilizada devido ao intenso desenvolvimento, que necessita de antenas que operem em multifrequências e em banda larga. As antenas de microfita apresentam largura de banda estreita devido às perdas no dielétrico geradas pela irradiação. Outra limitação é a degradação do diagrama de irradiação devido à geração de ondas de superfície no substrato. Outras técnicas estão sendo desenvolvidas para minimizar esta limitação de banda, como é o caso do estudo de materiais do tipo PBG – Photonic Band Gap, para compor o material dielétrico. Este trabalho tem como objetivo principal o estudo dos arranjos de antenas de microfita com patch retangular supercondutor. É apresentado um estudo das principais teorias que explicam o fenômeno microscópico e macroscópico da supercondutividade.  As teorias BCS, equações de London e modelo dos Dois Fluidos, são as teorias usadas nas aplicações dos supercondutores, nas antenas e arranjos de antenas de microfita. Os arranjos de fase são analisados em configurações lineares e planares. São obtidos os fatores de arranjos para estas configurações, e os critérios da fase e do espaçamento entre os elementos que compõem os arranjos, ao qual serão examinados, com o objetivo de minimizar as perdas no material, comparados com condutores normais. A antena com patch retangular, constituída de material supercondutor, com a temperatura crítica a 160K tem a fórmula química é SnBaCaCuOy. A análise é feita através do método dinâmico da Linha de Transmissão Transversa (LTT), desenvolvido por H.C.C.Fernandes, no domínio da transformada de Fourier (FTD). O método LTT é um método de onda completa, que tem como regra a obtenção dos campos eletromagnéticos em termos dos componentes transversais à estrutura. A inclusão do patch supercondutor é feita utilizando-se a condição de contorno complexa resistiva, usando-se a impedância do supercondutor na função Didática de Green, da estrutura. A eficiência dessas técnicas será investigada através de simulações realizadas pelo Ansoft HFSS, utilizado na análise precisa do comportamento eletromagnético dos respectivos arranjos de antenas linear e planar, através do método dos elementos finitos (FEM). São obtidos resultados da frequência de ressonância em função dos parâmetros da antena, utilizando material supercondutor, diagramas de radiação no Plano-E e no Plano-H, para os arranjos de fase de antenas nas configurações lineares e planares, bem como os seus respectivos ganhos.

5
  • RAPHAELA GALHARDO FERNANDES LIMA
  • Modelagem Semântica de Processos Industriais Com Aplicações

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • ADRIAO DUARTE DORIA NETO
  • VANJA MARIA DE FRANCA BEZERRA
  • CLAUDIA MARIA FERNANDES ARAÚJO RIBEIRO
  • RAIMUNDO SANTOS MOURA
  • Data: Feb 21, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho propõe uma ontologia orientada ao domínio de automação industrial, com o objetivo de modelagem semântica. Com o objetivo de estruturar conhecimento envolvido no contexto de processos industriais, esta tese propõe uma ontologia de domínio, denominada OntoAut, que modela conceitualmente dos elementos envolvidos na descrição de porcessos industriais. Para validar a ontologia proposta são apresentados diversas aplicações. Na primeira, são modelados conceitualmente dois processos típiocs: tratamento DEA (Dietanolamina) e forno industrial. Na segunda aplicação, utiliza-se a ontologia para realizar uma filtragem semântica de de alarmes, que aliada a analises de correlações, determina relações temporais entre alarmes de um processo industrial. Na terceira aplicação, utiliza-se a ontologia para modelagem e análise de custo de construção e operação de processos. Na quarta aplicação,  a ontologia é adotada para para analisar a confiabilidade de uma planta industrial.

6
  • VALDEZ ARAGAO DE ALMEIDA FILHO
  • Aplicação de Superfícies Seletivas em Frequência para Melhoria de Resposta de Arranjos de Antenas Planares

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • LAERCIO MARTINS DE MENDONCA
  • RONALDO DE ANDRADE MARTINS
  • ALFREDO GOMES NETO
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • Data: Mar 12, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como objetivo apresentar como a aplicação de superfícies seletivas em frequência (FSS) em arranjos de antenas planares se torna uma alternativa interessante para se obter características de radiação desejadas, a partir de alterações em parâmetros de radiação dos arranjos, tais como largura de banda, ganho e diretividade. Além de analisar esses parâmetros, também é feito o estudo do acoplamento mútuo entre os elementos do arranjo. Para realizar tal estudo, foi projetado um arranjo de antenas de microfita, com dois elementos do tipo patch, alimentado por uma rede de alimentação. Outra modificação feita no arranjo foi a utilização do plano de terra truncado, com o objetivo de aumentar a largura de banda e miniaturizar os elementos do arranjo. Para poder estudar o comportamento das superfícies seletivas em frequência aplicadas em arranjos de antenas, foram propostos três layouts diferentes. O primeiro layout consiste em utilizar a FSS como superstrato (acima do arranjo). O segundo consiste em utilizar a FSS como elemento refletor (abaixo do arranjo). O terceiro layout consiste em colocar o arranjo entre duas camadas de FSS, tanto em cima quanto abaixo. Resultados numéricos e experimentais para cada uma das configurações propostas são apresentados.

7
  • WELLINGTON CANDEIA DE ARAUJO
  • Síntese de Superfícies Seletivas de Frequência através de Técnicas de Computação Natural 

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • HERTZ WILTON DE CASTRO LINS
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • Data: Mar 17, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • As superfícies seletivas de frequência (FSS) têm sido objeto de intensa pesquisa nas duas últimas décadas, sendo utilizadas em diversas aplicações que vão desde sistemas de micro-ondas e antenas até aplicações em radomes e comunicações via satélite. Uma superfície seletiva de freqüência é um arranjo periódico que se constitui de elementos tipo patch ou abertura, ou mesmo por uma combinação de ambos, e exibe reflexão ou transmissão total na freqüência ressonante, se comportando dessa maneira como um filtro rejeita-faixa ou passa-faixa. Neste trabalho é realizada uma investigação numérica e experimental, consistindo do projeto, simulação computacional, construção e medição de estruturas de FSS. Esta FSS é estudada experimentalmente e suas características eletromagnéticas são medidas e simuladas através de programas de computador, equipamentos e técnicas de otimização. Estas estruturas são bastante complexas requerendo uma análise por técnicas de onda completa, como o método das diferenças finitas no domínio do tempo ou método dos elementos finitos. Para superar os custos computacionais e de tempo das técnicas de onda completa, podem ser utilizadas como alternativa as técnicas de computação natural. Algumas características como robustez, generalização, adaptabilidade e rápida convergência contribuem para o aumento significativo do emprego destas técnicas em aplicações na área de comunicações moveis. A modelagem das FSS citadas é realizada com redes neurais artificiais de múltiplas camadas, com o algoritmo de Levenberg-Marquardt para aprendizagem e treinamento. Os modelos neurocomputacionais desenvolvidos para as FSS proveem excelentes resultados e em concordância com valores obtidos através de medições em laboratório. A necessidade de estruturas com comportamento eletromagnético adequado em dispositivos de micro-ondas tem sido bastante estudada pelos pesquisadores da área. Essas estruturas requerem, em sua análise de características espectrais, técnicas rigorosas e elevada complexidade computacional em sua implementação. O objetivo desse trabalho consiste no projeto de FSSs através de redes neurais artificiais e outros algoritmos de computação natural selecionados, com aplicações na faixa de micro-ondas. A precisão dessa técnica é realizada experimentalmente e comparada com simulações efetuadas pelos softwares comerciais Ansoft Designer e Ansoft HFSS, utilizados na análise numérica do comportamento eletromagnético das FSSs através do Método dos Momentos (MoM) e do Método dos Elementos Finitos (FEM), respectivamente. Nesta tese um estudo bibliográfico em teoria de FSSs é realizado, bem como o estudo das redes neurais artificiais, algoritmos genéticos e outros algoritmos de otimização natural. Este estudo analisa também a solução da arquitetura de rede adequada aos projetos, algoritmos de treinamento, parâmetros dos algoritmos como número de neurônios nas camadas e quantidade de camadas das redes, bem como os parâmetros e funções adequadas para os algoritmos de otimização.

8
  • VINICIUS SAMUEL VALERIO DE SOUZA
  • WI-BIO: REDES DE MONITORAMENTO DE PACIENTES EM AMBIENTES DE AUTOMAÇÃO HOSPITALAR UTILIZANDO O PADRÃO IEEE 802.11

  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • GLAUCIO BEZERRA BRANDAO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • MARCOS CESAR MADRUGA ALVES PINHEIRO
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • RAIMUNDO VIEGAS JUNIOR
  • Data: Mar 17, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • O monitoramento de pacientes tende a sofrer uma depreciação nos próximos anos em
    virtude da escassez de recursos físicos e humanos nos hospitais. Diante disso, diversos
    trabalhos definem alternativas à melhoria desse monitoramento utilizando redes sem-fio.
    Nesses trabalhos, a rede é usada apenas para transferir dados gerados por sensores
    médicos, não existindo convivência com o tráfego presente na rede de dados do hospital.
    Esse aspecto, todavia, deve ser evitado, uma vez que existem demandas pela integração
    entre aplicações de usuário e de monitoramento de pacientes. Sendo assim, este artigo
    define um sistema de monitoramento de pacientes denominado Wi-Bio, voltado ao
    estabelecimento de redes IEEE 802.11 de monitoramento de pacientes que permitam o
    tráfego gerado por aplicações de usuário. A validação formal do Wi-Bio foi feita mediante o
    projeto de redes de Petri e sua análise de desempenho foi feita mediante simulações
    realizadas na ferramenta Network Simulator 2. A adoção dessa abordagem é justificada pelo
    fato das redes de Petri permitirem a verificação da correção lógica dos sistemas projetados,
    enquanto as simulações permitem uma análise comportamental do Wi-Bio em cenários de
    sobrecarga, onde diversos pacientes são monitorados. Os resultados atestaram a validade
    das redes de Petri projetadas e mostraram que o Wi-Bio é capaz de cumprir as metas
    temporais impostas pelos sensores médicos, promovendo uma integração eficiente entre o
    tráfego presente nas redes de dados e de monitoramento de pacientes. Conforme descrito,
    o Wi-Bio cumpriu seus objetivos, o que motiva trabalhos futuros visando complementar os
    resultados obtidos.

9
  • JOSE MEDEIROS DE ARAUJO JUNIOR
  • Identificação Não Linear Usando uma Rede Fuzzy Wavelet Neural Network Modificada

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • DANIELLE SIMONE DA SILVA CASILLO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OTACILIO DA MOTA ALMEIDA
  • TAKASHI YONEYAMA
  • Data: Mar 24, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Nas últimas décadas, as redes neurais têm se estabelecido como uma das principais ferramentas para a identificação de sistemas não lineares. Entre os diversos tipos de redes utilizadas em identificação, uma que se pode destacar é a rede neural wavelet (ou Wavelet Neural Network - WNN). Esta rede combina as características de multirresolução da teoria wavelet com a capacidade de aprendizado e generalização das redes neurais, fornecendo modelos mais exatos do que os obtidos pelas redes tradicionais. Uma evolução das redes WNN consiste em combinar a estrutura Neuro-Fuzzy ANFIS (Adaptive Neuro-Fuzzy Inference Systems) com estas redes, gerando-se a estrutura Fuzzy Wavelet Neural Network- FWNN.  Essa rede é muito similar às redes ANFIS, com a diferença de que os tradicionais polinômios presentes nos consequentes desta rede são substituídos por redes WNN. O presente trabalho realiza a identificação de sistemas dinâmicos não lineares a partir de uma rede FWNN modificada. Na estrutura proposta, somente funções wavelets são utilizadas nos consequentes. Desta forma, é possível obter uma simplificação da estrutura, diminuindo o número de parâmetros ajustáveis da rede. Para avaliar a performance da rede FWNN com essa modificação, é realizada uma análise de desempenho, verificando-se as vantagens, desvantagens e o custo-benefício quando comparada com outras estruturas FWNNs existentes na literatura. As avaliações são realizadas a partir da identificação de dois sistemas simulados tradicionalmente encontrados na literatura e um sistema real não linear, consistindo de um tanque de multisseções e não linear. Por fim, a rede foi utilizada para inferir valores de temperatura e umidade no interior de uma incubadora neonatal. A execução dessas análises baseia-se em vários critérios, tais como: erro médio quadrático, número de épocas de treinamento, número de parâmetros ajustáveis, variância do erro médio quadrático, entre outros. Os resultados encontrados demonstram a capacidade de generalização da estrutura modificada, apesar da simplificação realizada.

10
  • GLEYDSON DE AZEVEDO FERREIRA LIMA
  • Uma Abordagem para Evolução e Reconciliação de Linhas de Produtos de Software Clonadas
  • Advisor : SERGIO VIANNA FIALHO
  • COMMITTEE MEMBERS :
  • SERGIO VIANNA FIALHO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • EDUARDO HENRIQUE DA SILVA ARANHA
  • UIRA KULESZA
  • PAULO HENRIQUE MONTEIRO BORBA
  • VANDER RAMOS ALVES
  • Data: Mar 31, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Linhas de produtos de software promovem a reutilização em larga escala através do desenvolvimento de famílias de sistemas que:
    (i) compartilham um núcleo comum de características previamente implementadas; e (ii) permitem a seleção e customização das características variáveis, as quais determinam os comportamentos distintos de cada membro ou produto da família de sistema.  Por razões de time-to-market e flexibilidade, a indústria de software tem adotado, com frequência, a técnica de clonagem como mecanismo de criação de produtos ou de novas linhas de produtos.  Apesar das suas vantagens, a técnica de clonagem traz dificuldades para a evolução e reconciliação de características de linhas de produto de software devido aos possíveis conflitos de integração das mudanças realizadas no código da linha de produto de software original, denominada Source, e a da linha de produto clonada, denominada Target.  Esta tese de doutorado propõe uma abordagem para evolução e reconciliação de produtos clonadas baseada na adoção de técnicas de mineração de repositórios de software. A abordagem promove a identificação de
    diferentes tipos de conflitos - léxicos, estruturais e semânticos - que podem ocorrer durante a integração de características ou tarefas de desenvolvimento da linha de produto original para a linha de produto clonada. O trabalho apresenta os resultados de um estudo empírico de caracterização dos tipos de conflitos de integração de código em diferentes evoluções de duas linhas de produto de software de sistemas de informação web. Os resultados do estudo demonstram o potencial da abordagem na resolução automática ou semi-automática de vários dos conflitos existentes, reduzindo assim os custos de evolução e reconciliação de linhas de produto de software clonadas.

11
  • MARINALDO PINHEIRO DE SOUSA NETO
  • Um Estudo de Metamaterial em Antenas de Microfita

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • HUMBERTO DIONISIO DE ANDRADE
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Data: Apr 25, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Os metamateriais tem atraído uma grande atenção nas ultimas décadas, principalmente devido as suas propriedades eletromagnéticas não encontradas na natureza. Desde que os metamateriais passaram a ser sintetizado através da inserção de inclusões artificialmente fabricadas num meio host especificado, isto propicia ao pesquisador uma larga coleção de parâmetros independentes, tal como as propriedades eletromagnéticas do material host. Foi realizada uma investigação das propriedades dos Ressoadores em anel e dos metamateriais. Esta Tese de Doutorado apresenta uma análise teórica, numérico-computacional e experimental, utilizando o formalismo de onda completa através da aplicação do método da Linha de Transmissão Transversa – LTT, e o uso do software Ansoft HFSS, das características ressonantes, campos, diagramas de irradiação, perdas de retorno, ganho, diretividade, densidades de corrente,  de diferentes antenas de microfita com patch retangular utilizando substrato metamaterial, assim como é demonstrado com sucesso a utilização prática dessas estruturas em antenas fabricadas em laboratório. 

12
  • GUSTAVO ARAÚJO CAVALCANTE
  •  Desenvolvimento de Circuitos Planares sobre Substratos Têxteis


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • MARCOS TAVARES DE MELO
  • SILVIO ERNESTO BARBIN
  • Data: Apr 28, 2014


  • Show Abstract
  • A utilização de materiais flexíveis para o desenvolvimento de circuitos planares é uma das características mais desejadas e estudadas, ultimamente, pelos pesquisadores, pois essa maleabilidade do substrato proporciona aplicações antes impossíveis, devido à rigidez dos substratos normalmente utilizados o que dificultava a adequação dos circuitos em superfícies irregulares. O constante interesse nos últimos anos por dispositivos mais leves, cada vez mais compactos, flexíveis e com custo reduzido, levou a uma nova linha de pesquisa de grande interesse tanto do ponto de vista acadêmico quanto tecnológico que é o estudo e desenvolvimento de substratos têxteis que possam ser aplicados no desenvolvimento de circuitos planares, para aplicações nas áreas de segurança, biomédica e telecomunicações. Este trabalho propõem o desenvolvimento de circuitos planares (antenas, superfícies seletivas de frequência – FSS e filtros planares) utilizando tecidos (lona, jeans e brin santista) como substrato dielétrico e o tecido Pure Copper Polyester Taffeta Fabric, tecido de cobre puro, altamente condutivo, leve e flexível comercialmente vendido como material condutivo. As características elétricas dos tecidos (permissividade elétrica e tangente de perda) foram caracterizadas utilizando o método de linha de transmissão (guia de onda retangular) e comparadas com os encontrados na literatura. As estruturas foram analisadas utilizando os softwares comerciais Ansoft Designer, Ansoft HFSS ambos da empresa Ansys e para efeito de comparação foi utilizado o Método Iterativo das Ondas (WCIP). Para efeito de validação foram construídos e medidos vários protótipos de antenas, FSS e filtros planares sendo possível constatar uma excelente concordância entre os resultados simulados e medidos.



13
  • BRUNO SIELLY JALES COSTA
  • Detecção e Diagnóstico de Falhas Não-supervisionados Baseados em Estimativa de Densidade Recursiva e Classificador Fuzzy Auto-evolutivo

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • ADRIAO DUARTE DORIA NETO
  • DANIEL ALOISE
  • MARLEY MARIA BERNARDES REBUZZI VELLASCO
  • PLAMEN ANGELOV
  • Data: May 13, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho propõe um algoritmo de dois estágios para detecção e identificação de falhas, em tempo real, de plantas industriais. A proposta baseia-se na análise de características selecionadas utilizando estimativa de densidade recursiva e um novo algoritmo evolutivo de classificação. Mais especificamente, a abordagem proposta para detecção é baseada no conceito de densidade no espaço de dados, o que difere da tradicional função densidade de probabilidade, porém, sendo uma medida bastante útil na detecção de anormalidades/outliers. Tal densidade pode ser expressa por uma função de Cauchy e calculada recursivamente, o que torna o algoritmo computacionalmente eficiente, em termos de processamento e memória, e, dessa maneira, apropriado para aplicações on-line. O estágio de identificação/diagnóstico é realizado por um classificador baseado em regras fuzzy capaz de se auto-desenvolver (evolutivo), chamado de AutoClass, e introduzido neste trabalho. Uma propriedade importante do AutoClass é que ele é capaz de aprender a partir "do zero". Tanto as regras fuzzy, quanto o número de classes para o algoritmo não necessitam de pré-especificação (o número de classes pode crescer, com os rótulos de classe sendo adicionados pelo processo de aprendizagem on-line), de maneira totalmente não-supervisionada. Nos casos em que uma base de regras inicial existe, AutoClass pode evoluir/desenvolver a partir dela, baseado nos dados adquiridos posteriormente. De modo a validar a proposta, o trabalho apresenta resultados experimentais de simulação e de aplicações industriais reais, onde o sinal de controle e erro são utilizados como características para os estágios de detecção e identificação, porém a abordagem é genérica, e o número de características selecionadas pode ser significantemente maior, devido à metodologia computationalmente eficiente adotada, uma vez que cálculos mais complexos e armazenamento de dados antigos, não são necessários. Os resultados obtidos são significativamente melhores que os gerados pelas abordagens tradicionais.

14
  • FABIO SOARES DE LIMA
  • Detecção e Classificação de Modos de Operação do Bombeio Mecânico Via Cartas Dinamométricas

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • DIEGO RODRIGO CABRAL SILVA
  • RUTACIO DE OLIVEIRA COSTA
  • BENNO WALDEMAR ASSMANN
  • DANIEL SABINO AMORIM DE ARAUJO
  • Data: May 30, 2014


  • Show Abstract
  • A identificação rápida e precisa de anormalidades de fundo de poço é essencial para evitar danos e aumentar a produção na indústria do petróleo. Esta tese apresenta um estudo sobre uma nova abordagem automática para a detecção e classificação de modos de operação no sistema de Bombeio Mecânico através de carta de dinamométricas de fundo de poço. A idéia principal é o reconhecimento das condições de produção do sistema através do processamento de imagem do carta dinamométrica de fundo de poço (Descritores de Contorno) e ferramentas matemáticas estatísticas e de similaridade, como Descritores de Fourier, Análise de Componentes Principais (PCA) e Distância Euclidiana. Para validar a proposta, são utilizados dados provenientes de sistemas de Bombeio Mecânico reais.

15
  • RAFAEL NUNES DE ALMEIDA PRADO
  • IMPLEMENTAÇÃO DE UMA ARQUITETURA FUZZY NEURAL EM HARDWARE COM TREINAMENTO ONLINE

  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • JORGE DANTAS DE MELO
  • ADRIAO DUARTE DORIA NETO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • DANNIEL CAVALCANTE LOPES
  • NADIA NEDJAH
  • Data: Jun 6, 2014


  • Show Abstract
  • Os métodos de Inteligência Computacional vêm adquirindo espaço nas aplicações industriais devido a sua capacidade de solução de problemas na engenharia, conseqüentemente, os sistemas embarcados acompanham a tendência do uso das ferramentas computacionais inteligentes de forma embarcada em máquinas. Existem diversos trabalhos na área de sistemas embarcados e sistemas inteligentes puros ou híbridos, porém, são poucos os que uniram ambas as áreas em um só projeto. O objetivo deste trabalho foi implementar um sistema fuzzy neural adaptativo em hardware com treinamento online para embarque em Field Programable Gate Array – FPGA. A adaptação do sistema pode ocorrer durante a execução de uma determinada aplicação, visando melhora do desempenho de forma online. A arquitetura do sistema é modular, possibilitando a configuração de várias topologias de redes fuzzy neurais com treinamento online. Verificou-se que o sistema proposto obteve desempenho satisfatório quando aplicado a problemas de interpolação, classificação de padrões e a problemas industriais. Diante dos resultados dos experimentos foram discutidas as vantagens e desvantagens do treinamento online em hardware ser realizado de forma paralela e serializada, esta última forma proporcionou economia na área utilizada de FPGA, já a forma de treinamento paralelo demonstrou alto desempenho e reduzido tempo de processamento. O trabalho utilizou ferramentas de desenvolvimento disponíveis para circuitos FPGA.

16
  • RODRIGO SIQUEIRA MARTINS
  • Método Híbrido para Detecção e Diagnóstico de Falhas Baseado em Resíduos

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • BENNO WALDEMAR ASSMANN
  • DANIELLE SIMONE DA SILVA CASILLO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • Data: Jun 27, 2014


  • Show Abstract
  • A detecção e o diagnóstico de falhas, ou seja, descobrir como, onde e porque as falhas acontecem, é uma importante área de estudo desde que o homem passou a ser substituído pelas máquinas. No entanto, nenhuma técnica estudada até hoje consegue resolver em definitivo o problema. As diferenças em sistemas dinâmicos, sejam eles lineares, não lineares, variantes ou invariantes no tempo, com redundância física ou mesmo analítica dificultam as pesquisas no sentido de obter uma solução única. Neste trabalho, será apresentada uma técnica de detecção e diagnósticos de falhas (FDD) em sistemas dinâmicos utilizando observadores de estado em conjunto com outras ferramentas de maneira a criar um FDD híbrido. Um observador de estado modificado será utilizado para a criação de um resíduo que permita a detecção e também o diagnósticos de falhas. Um banco de assinaturas de falhas será criado a partir de recortes utilizando ferramentas estatísticas e por fim uma aproximação usando erro médio quadrático (MSE) servirá de inferência e auxiliará no estudo do comportamento das falhas e no diagnóstico das mesmas, ainda que na presença de ruídos. Essa metodologia será então aplicada a uma planta didática de tanques acopladas e outra com instrumentação industrial com fim de validar o sistema.

17
  • MARCELO ROBERTO BASTOS GUERRA VALE
  • Sistema Híbrido para Detecção e Diagnóstico de Falhas em Sistemas Dinâmicos

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDRE LAURINDO MAITELLI
  • DANIELLE SIMONE DA SILVA CASILLO
  • OSCAR GABRIEL FILHO
  • VICENTE DELGADO MOREIRA
  • Data: Jun 27, 2014


  • Show Abstract
  • As indústrias estão cada vez mais rígidas quando o assunto é segurança, tanto para evitar prejuízos financeiros com acidentes e baixa produtividade, quanto para preservar o meio ambiente. Diante dos grandes acidentes em todo o mundo envolvendo aeronaves e processos industriais (nucleares, petroquímicos etc) procurou-se investir em sistemas que pudessem detectar e diagnosticar falhas(FDD-Fault Detection and Diagnosis). Os sistemas FDD podem evitar eventuais falhas auxiliando o homem na manutenção e troca de equipamentos defeituosos. Nos dias de hoje os assuntos que envolvem detecção, isolamento, identificação e diagnóstico de falhas estão ganhando força no meio acadêmico e industrial. Diante deste impulso, neste trabalho, será discutido a importância do estudo de técnicas que possam auxiliar o desenvolvimento de sistemas de detecção e diagnóstico de falhas e proposto um método híbrido para a detecção e diagnóstico de falhas em sistemas dinâmicos. Um breve histórico é apresentado de forma a contextualizar as técnicas utilizadas no trabalho. A detecção de falha do sistema proposto é baseada em observadores de estado juntamente com outras técnicas estatísticas. A ideia principal é utilizar o próprio observador, para além de servir como redundância analítica, permitir a criação de um resíduo. Este resíduo será utilizado na detecção da falha e também no seu diagnóstico. Um banco de assinaturas auxiliará o sistema de identificação de falhas, que, baseado nas assinaturas oriundas das análises de tendência do sinal do resíduo e sua derivada, irá realizar a classificação das falhas baseada em uma árvore de decisão. Este sistema FDD será submetido a alguns testes e validações em duas plantas: uma planta simulada de tanques acoplados e em um planta didática com instrumentação industrial. Todos os resultados colhidos desses ensaios serão discutidos.

18
  • JOILSON BATISTA DE ALMEIDA REGO
  • Extensões Multidimensionais para Correntropia e suas Aplicações em Estimativas Robustas

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ADRIAO DUARTE DORIA NETO
  • AARAO LYRA
  • EVANDRO DE BARROS COSTA
  • GUILHERME DE ALENCAR BARRETO
  • Data: Aug 8, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • Motivado pelos recentes avanços científicos na área de ITL, venho através desde trabalho apresentar um novo algoritmo que estende as aplicações de correntropia para estimadores lineares. Esta nova extensão calcula correntropia em qualquer dimensão, em vez de apenas comparar duas variáveis como apresentado na definição original. A correntropia apresenta várias propriedades interessantes que conecta áreas como ITL, métodos de Kernel e estimadores robustos. A organização da tese é a seguinte. Após um breve histórico sobre ITL e métodos de Kernel para introduzir as terminologias, algumas definições sobre teoria de informação são apresentadas no capítulo 02. No capítulo 03, apresentamos a definição da entropia e da entropia quadratica de Rényi bem como a conceituação de potencial de informação – IP, apresentamos também a definição e aplicações do Espaço de Hilbert Reproduzido por Kernel – RKHS e uma introdução à unificação entre ITL e métodos de Kernel ou aprendizagem estatística. No capítulo 04 será discutido as contribuições deste trabalho na extensão do conceito da correntropia para espaço muitidimensional e finalmente, no capítulo 05 será apresentado a aplicação dos conceitos da correntropia para espaço multidimensional na identificação de sistemas lineares robustos e as conclusões.

19
  • ANNA GISELLE CAMARA DANTAS RIBEIRO RODRIGUES
  • Um Sistema Inteligente de Tele-oftalmologia para auxílio no diagnostico de Catarata

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ADRIANO DE ANDRADE BRESOLIN
  • ANA MARIA GUIMARAES GUERREIRO
  • CICILIA RAQUEL MAIA LEITE
  • HELIANA BEZERRA SOARES
  • MARCELO AUGUSTO COSTA FERNANDES
  • Data: Sep 6, 2014


  • Show Abstract
  • O aumento da população mundial, com proporção maior de idosos, acarreta no aumento do número de indivíduos com perda visual, sendo a catarata a maior causa de cegueira no mundo. A Catarata é uma patologia dos olhos que consiste na opacidade parcial ou total do cristalino (lente natural do olho) ou de sua cápsula. Pode ser desencadeada por vários fatores, como traumatismo, idade, diabetes mellitus, uso de medicamentos, entre outros. Sabe-se que o atendimento por oftalmologistas no Brasil nas áreas rurais e mais pobres é inferior ao necessário e muitos pacientes com doenças tratáveis como a Catarata ficam sem diagnóstico e consequentemente sem tratamento.

    Neste contexto, esse projeto tem como proposta o desenvolvimento do OPTICA, um sistema de tele-oftalmologia que utiliza smartphones para detecção de urgências oftalmológicas, disponibilizando um auxílio ao diagnóstico a Catarata utilizando sistemas inteligentes e técnicas de processamento de imagens. As imagens serão capturadas por um celular com uma lente especial acoplada a câmera e juntamente com um questionário com informações do paciente serão transmitidos de forma segura via a plataforma Sana Mobile (sana.mit.edu) para uma central online de laudos que dispõe de um programa inteligente de auxilio ao diagnóstico a Catarata e de médicos oftalmologistas que irão analisar as informações e emitir o laudo do paciente.

    Desta forma, o OPTICA  permite levar atendendimento oftalmológico a população menos favorecida e em áreas remotas , melhorando a triagem de pacientes graves e aumentando o acesso ao diagnóstico e tratamento. 

20
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • Estratégias de Busca Reativa Utilizando Aprendizagem por Reforço e Algoritmos de Busca Local

  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DANIEL ALOISE
  • DARIO JOSE ALOISE
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • GEORGE DARMITON DA CUNHA CAVALCANTI
  • JORGE DANTAS DE MELO
  • Data: Sep 12, 2014


  • Show Abstract
  • Técnicas de otimização conhecidas como as metaheurísticas tem conseguido resolver
    satisfatoriamente problemas conhecidos, mas desenvolvimento das metaheurísticas é
    caracterizado por escolha de parâmetros para sua execução, na qual a opção apropriada
    destes parâmetros (valores). Onde o ajuste de parâmetro é essencial testa-se os parâmetros
    até que resultados viáveis sejam obtidos, normalmente feita pelo desenvolvedor que esta
    implementando a metaheuristica. A qualidade dos resultados de uma instância1 de teste
    não será transferida para outras instâncias a serem testadas e seu feedback pode requerer
    um processo lento de “tentativa e erro” onde o algoritmo têm que ser ajustado para uma
    aplicação especifica. Diante deste contexto das metaheurísticas surgiu a Busca Reativa
    que defende a integração entre o aprendizado de máquina dentro de buscas heurísticas
    para solucionar problemas de otimização complexos. A partir da integração que a Busca
    Reativa propõe entre o aprendizado de máquina e as metaheurísticas, surgiu a ideia de
    se colocar a Aprendizagem por Reforço mais especificamente o algoritmo Q-learning de
    forma reativa, para selecionar qual busca local é a mais indicada em determinado instante
    da busca, para suceder uma outra busca local que não pode mais melhorar a solução
    corrente na metaheurística VNS. Assim, neste trabalho propomos uma implementação reativa,
    utilizando aprendizado por reforço para o auto-tuning do algoritmo implementado,
    aplicado ao problema do caixeiro viajante simétrico e ao problema escalonamento sondas
    para manutenção de poços.
21
  • ERICO CADINELI BRAZ
  • Análise de Superfícies Seletivas em Frequência com Geometrias Multifractais

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • HUMBERTO CESAR CHAVES FERNANDES
  • JOSE PATROCINIO DA SILVA
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • Data: Sep 25, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • As superfícies seletivas em frequência são estruturas cada vez mais comuns em sistemas de telecomunicações por apresentarem vantagens físicas e eletromagnéticas. Já as superfícies seletivas em frequência com geometria do tipo fractal permitiu uma redução, ainda maior, no tamanho dessas
    estruturas. Neste trabalho, é investigado o uso das geometrias Multifractais nas superfícies seletivas em frequência. A principal vantagem da estrutura proposta sobre as convencionais é permitir projetar estruturas Multibanda com maior flexibilidade no controle das frequências de ressonâncias e largura de banda. Além disso, a estrutura proposta aumenta o grau de liberdade nos projetos Multibanda, pois possui múltiplas razões de frequências de ressonâncias entre as bandas adjacentes, e são fáceis de implementar. A validação da estrutura proposta foi verificada inicialmente através de simulações realizadas no software Ansoft Designer e em seguida foram construídas as estruturas e obtidos os resultados experimentais.

22
  • TEOFILO CAMARA MATTOZO
  • Contribuições de modelagem de equações estruturais na análise de dados em modelos comportamentais de destino turístico

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • LAERCIO MARTINS DE MENDONCA
  • PAULO CESAR FORMIGA RAMOS
  • ANTONIO JANIO FERNANDES
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • NILDA MARIA DE CLODOALDO PINTO GUERRA LEONE
  • Data: Oct 8, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • A fragilidade brasileira quanto à competitividade turística é um fato observável nos dados da Organização Mundial do Turismo. O Brasil caiu em 2011, da 45ª para a 52ª posição, apesar de liderar no atributo recursos naturais e estar colocado na 23° em recursos culturais. Assim, grandes interesses e esforços têm sido direcionados para o estudo da competitividade dos produtos e destinos turísticos. O destino turístico é caracterizado por um conjunto complexo e articulado de fatores tangíveis e intangíveis, apresentando alta complexidade, dados de elevada dimensionalidade, não linearidade e comportamento dinâmico, tornando-se difícil a modelagem desses processos por meio de abordagens baseadas em técnicas estatísticas clássicas. Esta tese investigou modelos de equações estruturais e seus algoritmos, aplicados nesta área, analisando o ciclo completo de análise de dados, em um processo confirmatório no desenvolvimento e avaliação de um modelo holístico da satisfação do turista; na validação da estrutura do modelo de medida e do modelo estrutural, por meio de testes de invariância de múltiplos grupos; na análise comparativa dos métodos de estimação MLE, GLS e ULS para a modelagem da satisfação e na realização de segmentação de mercado no setor de destino turístico utilizando mapas auto-organizáveis de Kohonen e sua validação com modelagem de equações estruturais. Aplicações foram feitas em análises de dados no setor de turismo, principal indústria de serviços do Estado do Rio Grande do Norte, tendo sido, teoricamente desenvolvidos e testados empiricamente, modelos de equações estruturais em padrões comportamentais de destino turístico. Os resultados do estudo empírico se basearam em pesquisas com a técnica de amostragem aleatória sistemática, efetuadas em Natal-RN, entre Janeiro e Março de 2013 e forneceram evidências sustentáveis de que o modelo teórico proposto é satisfatório, com elevada capacidade explicativa e preditiva, sendo a satisfação o antecedente mais importante da lealdade no destino. Além disso, a satisfação é mediadora entre a geração da motivação da viagem e a lealdade do destino e que os turistas buscam primeiro à satisfação com a qualidade dos serviços de turismo e, posteriormente, com os aspectos que influenciam a lealdade. Contribuições acadêmicas e gerenciais são mostradas e sugestões de estudo são dadas para trabalhos futuros. 

23
  • EVERTON SANTI
  • Formulações e algoritmos para o problema das p-medianas heterogêneo livre de penalidade

  • Advisor : DANIEL ALOISE
  • COMMITTEE MEMBERS :
  • DANIEL ALOISE
  • ADRIAO DUARTE DORIA NETO
  • CAROLINE THENNECY DE MEDEIROS ROCHA
  • SEBASTIAN ALBERTO URRUTIA
  • SIMON BLANCHARD
  • Data: Nov 14, 2014


  • Show Abstract
  • Apresenta-se neste trabalho uma nova formulação para o Problema das p-medianas Heterogêneo (HPM), proposto para recuperar a estrutura de categorias presente em dados oriundos de uma tarefa de classificação (sorting task). Esta nova formulação é denominada Problema das p-medianas Heterogêneo Livre de Penalidade (PFHPM), uma versão convexa e mono-objetivo do HPM, na qual seu principal parâmetro é eliminado. Este parâmetro, um fator de penalidade, é responsável pela ponderação dos elementos de sua função objetivo. O ajuste deste parâmetro tem influência no modo como o modelo original recupera a estrutura de categorias, dependendo de conhecimento prévio acerca do problema para que este não gere classificações errôneas. Neste trabalho, ainda, duas formulações complementares são apresentadas para o PFHPM, a partir das quais pôde-se obter limitantes inferiores otimistas para o problema. No contexto desta pesquisa, estes limitantes são utilizados para validar um algoritmo de Busca em Vizinhança Variada (VNS) proposto para resolver o PFHPM. Este algoritmo mostrou-se eficiente, obtendo soluções de boa qualidade para o problema, tanto para instâncias geradas por Simulação de Monte Carlo quanto para dados reais, a um custo computacional baixo. As estatísticas mostradas neste trabalho sugerem que o novo algoritmo e a nova formulação do HPM apresentam maior precisão que o modelo original, tanto na recuperação da estrutura de categorias quanto na percepção heterogênea da informação. Finalmente, um exemplo de aplicação do PFHPM é mostrado, assim como alguns direcionamentos futuros, propondo-se a extensão da nova formulação apresentada a ambientes fuzzy.

24
  • RAPHAELL MACIEL DE SOUSA
  • Contribuições à Estratégia de Controle Sem Detecção de Harmônicos Aplicada a Um Filtro Ativo de Potência Paralelo

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ANTONIO MARCUS NOGUEIRA LIMA
  • FLAVIO BEZERRA COSTA
  • MARCELO CABRAL CAVALCANTI
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • VALENTIN OBAC RODA
  • Data: Nov 24, 2014


  • Show Abstract
  • Os esquemas que empregam compensação ativa, conhecidos como
    filtros ativos de potência (FAP), usualmente tem sido utilizados para
    resolver problemas relativos à qualidade de energia, sobretudo, distorção
    nas formas de onda (harmônicos). O filtro ativo de potência paralelo (FAPP)
    comumente é utilizado para compensar componentes harmônicos de corrente.
    Para tanto, utiliza técnicas de extração de harmônicos para geração das
    referências (controle direto). Tais referências também podem ser geradas
    através do balanço de potência do sistema, sem a necessidade de extração de
    harmônicos (controle indireto). Este trabalho propõe ampliar a capacidade
    de compensação da estrutura de controle indireta, que usualmente é
    utilizada no FAPP para compensar componentes harmônicos provenientes de uma
    carga não linear conectada a um ponto comum de acoplamento (PAC). Espera-se
    que a estrutura proposta seja capaz de amortecer oscilações de tensão
    provocadas por distúrbios transitórios, atuando como um sistema de
    estabilização de potência conectado a um protótipo de linha de transmissão
    desenvolvido em laboratório. Além disso, é proposto neste trabalho uma
    simples modificação na geração das referências do controle indireto que
    permite a flexibilização da compensação de reativos, mantendo o FAPP dentro
    dos limites de potência disponível. Resultados experimentais são
    apresentados para demonstrar a capacidade de compensação da estrutura de
    controle proposta para o FAPP.
25
  • RICARDO FERREIRA PINHEIRO FILHO
  • ESTUDO DE UM SISTEMA DE FRENAGEM ELETROMAGNÉTICA EMPREGANDO CORRENTES PARASITAS

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALBERTO SOTO LOCK
  • ANDRES ORTIZ SALAZAR
  • CARLOS EDUARDO TRABUCO DOREA
  • FILIPE DE OLIVEIRA QUINTAES
  • JOSSANA MARIA DE SOUZA FERREIRA
  • Data: Nov 28, 2014
  • View Dissertation/Thesis  

  • Show Abstract
  • O presente trabalho trata do estudo analítico, computacional e experimental dos fenômenos relacionados à indução de correntes parasitas em meios metálicos de baixa permeabilidade para aplicações em sistemas de frenagem eletromagnética embarcadas. São enfocados os fenômenos de geração de forças que se opõem à variação de fluxos magnéticos estacionários, produzidos por alimentação em corrente contínua, postos em movimento pela aplicação de uma força propulsora externa. O estudo é motivado pela busca por solucionar o problema do controle de velocidade dos PIG’s empregados na verificação e manutenção de tubulações, e é conduzido com base na sintetização de modelos analíticos, os quais são validados por intermédio de simulações computacionais no ambiente dos Elementos Finitos, providas por softwares de apoio à engenharia; e por meio de ensaios experimentais conduzidos em laboratório sob condições controladas. Por fim, é apresentada uma metodologia para o projeto de sistemas de frenagem dessa natureza com base nos resultados obtidos das análises desenvolvidas ao longo do estudo.

26
  • ALEXSANDRA OLIVEIRA ANDRADE
  • Sistema de Contagem com Morfologia Matemática Fuzzy

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • BENEDITO MELO ACIOLY
  • HELIANA BEZERRA SOARES
  • REGIVAN HUGO NUNES SANTIAGO
  • ROQUE MENDES PRADO TRINDADE
  • Data: Nov 29, 2014


  • Show Abstract
  • A Morfologia Matemática apresenta um modelo sistemático para extrair características geométricas de imagens binárias usando operadores morfológicos que transformam a imagem original em outra usando uma terceira imagem chamada elemento estruturante e teve origem em 1960 pelos pesquisadores Jean Serra e George Matheron.  A morfologia matemática fuzzy estende os operadores morfológicos para imagens em tons de cinza e coloridas e foi inicialmente  proposta por Goetherian. Neste trabalho propõem-se o desenvolvimento de um sistema adaptativo para a segmentação de imagens baseado em morfologia matemática fuzzy. As conjunções e implicações da fundamentação matemática da morfologia fuzzy serão utilizadas para escolher a melhor adjunção a ser aplicada dependendo do problema a ser abordado, ou seja, utilizaremos automorfismos sobre as implicações e observaremos a influência na segmentação das imagens e posteriormente no processamento das mesmas. Para validação do sistema desenvolvido será aplicado em problemas de contagem em imagens microscópicas estendendo-se para imagens patológicas.

27
  • LINCOLN MACHADO DE ARAUJO
  • Caracterização de Superfícies Seletivas de Frequência Periódicas e Não-Periódicas


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • HERTZ WILTON DE CASTRO LINS
  • LAERCIO MARTINS DE MENDONCA
  • Data: Dec 15, 2014


  • Show Abstract
  • Os últimos anos foram marcados por um grande interesse no uso de superfícies seletivas de frequência (FSS), como filtros espaciais, em diversas aplicações em micro-ondas. Dentre estas, destacam-se as aplicações em sistemas de telecomunicações (tais como: comunicações por satélite e radar), antenas de ganho elevado (em estruturas combinadas com antenas planares) e fornos de micro-ondas (domésticos e industriais). As FSS são geralmente compostas por arranjos periódicos bidimensionais (com elementos igualmente espaçados), que podem ser metálicos (impressos em substratos dielétricos), ou de aberturas (perfuradas em superfícies metálicas finas). Nestas configurações (de arranjos periódicos), as FSS vêm conseguindo atender às demandas da indústria de telecomunicações de maneira satisfatória. Entretanto, novas demandas vêm encontrando limitações na tecnologia empregada. Neste contexto, requisitos de filtragem adversos vêm forçando os projetistas de FSS a utilizarem métodos de otimização na tentativa de encontrar formatos específicos para seus elementos, por exemplo. Outra alternativa que vem sendo utilizada para aumentar a seletividade das FSS é o cascateamento, uma técnica simples que tem como principal ponto negativo o aumento das dimensões da estrutura, assim como do seu peso. Este trabalho propõe o desenvolvimento de uma nova classe de superfícies seletivas de frequência (FSS), constituídas de arranjos quase-periódicos (ou não-periódicos). Portanto, as FSS propostas apresentam uma periodicidade variável, dependente da posição espacial dos elementos metálicos que a compõe. As respostas em frequência destas estruturas foram simuladas utilizando softwares comerciais que implementam métodos de onda completa. Para validação do estudo efetuado, foram construídos e medidos protótipos das FSS propostas, tendo sido observada uma boa concordância entre os resultados simulados e medidos. São apresentadas e comentadas as principais conclusões deste estudo, além de indicadas sugestões para a sua continuidade.

28
  • ALESSANDRA MENDES PACHECO
  • Técnica para Auto-Segmentação de Componentes Sanguíneos e Classificação Diferencial de Leucócitos Baseada em Lógica Fuzzy

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • CICILIA RAQUEL MAIA LEITE
  • MARCO ANTONIO GARCIA DE CARVALHO
  • Data: Dec 26, 2014


  • Show Abstract
  • A detecção automática de componentes sanguíneos em imagens microscópicas é um importante tópico da área hematológica. A segmentação permite que os componentes sanguíneos sejam agrupados em áreas comuns e a classificação diferencial dos leucócitos possibilita que os mesmos sejam analisados separadamente. Com a auto-segmentação e classificação diferencial, contribui-se no processo de análise dos componentes sanguíneos, fornecendo ferramentas que propiciem a diminuição do trabalho manual e o aumento da sua precisão e eficiência. Utilizando técnicas de processamento digital de imagens associadas a uma abordagem fuzzy genérica e automática, este trabalho propõe dois Sistemas de Inferência Fuzzy, definidos como I e II, para a auto-segmentação de componentes sanguíneos e classificação diferencial de leucócitos, respectivamente, em imagens microscópicas de esfregaços. Considerando inicialmente os níveis de cinza presentes no canal G da imagem (modelo RGB), a proximidade entre os centróides dos núcleos leucocitários e os demais pixels que a compõem e utilizando o Sistema de Inferência Fuzzy I, a técnica proposta realiza a segmentação da imagem em quatro regiões: núcleo e citoplasma leucocitários, eritrócitos e área de plasma. Após a segmentação e considerando apenas os leucócitos (núcleo e citoplasma), os classifica diferencialmente utilizando descritores de forma e textura já conhecido e outros descritores definidos neste trabalho e o Sistema de Inferência Fuzzy II. Foram utilizadas para testes 530 imagens contendo amostras microscópicas de esfregaços sanguíneos corados com métodos variados. As imagens foram processadas e seus índices de Acurácia e Gold Standards foram calculados e comparados com os resultados manuais e com outros resultados encontrados na literatura para os mesmos problemas. Quanto à segmentação, a técnica desenvolvida demonstrou percentuais de acurácia de 97,31% para leucócitos, 95,39% para eritrócitos e 95,06% para plasma sanguíneo. Quanto à classificação diferencial, os percentuais variaram entre 92,98% e 98,39% para os diferentes tipos leucocitários. Além de promover a auto-segmentação e classificação diferencial, a técnica proposta contribui ainda com definição de novos descritores e a construção de um banco de imagens utilizando diversos processos de coloração hematológicos.

2013
Dissertations
1
  • CARLA DA COSTA FERNANDES CURVELO
  • S-Educ: Um Simulador de Ambiente de Robótica Educacional em Plataforma Virtual

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • EDUARDO OLIVEIRA FREIRE
  • Data: Jan 30, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Propomos uma plataforma de simulação robótica, denominada S-Educ, desenvolvida especificamente para aplicação em robótica educacional, que pode ser usada como uma alternativa ou em conjunto com kits de robôs em aulas envolvendo uso da robótica. Na abordagem usualmente conhecida, a robótica educacional utiliza-se de kits de robótica em aulas que geralmente contemplam temas interdisciplinares. A ideia deste trabalho não é substituir esses kits, mas sim usar o simulador desenvolvido como uma alternativa, onde, por algum motivo, os kits tradicionais não possam ser usados, ou até mesmo usar a plataforma em conjunto com esses kits. Para o desenvolvimento dos trabalhos, realizamos inicialmente uma pesquisa bibliográfica acerca da utilização de simuladores robóticos voltados para a área educacional, e de kits robóticos, a partir da qual foi possível definir um conjunto de funcionalidades consideradas importantes para a criação de tal ferramenta. Em seguida, na fase de desenvolvimento de software, foi implementado o simulador S-Educ, levando em consideração os requisitos e funcionalidades definidos na fase de projeto. Por fim, para validar a plataforma, foram realizados vários testes com professores, alunos e adultos leigos, nos quais foi utilizado o simulador S-Educ, visando avaliar a sua utilização em aulas de robótica educacional. Os resultados mostram que simuladores robóticos possibilitam uma redução de custos financeiros, facilitam os testes e diminuem os danos, devido ao uso, no robô, além de outras vantagens. Além disso, como contribuição à comunidade, a ferramenta proposta pode ser usada para aumentar a adesão das escolas brasileiras às metodologias de robótica educacional, ou em competições de
    robótica.

2
  • ALLAN ROBSON SILVA VENCESLAU
  • DETECCAO E DIAGNOSTICO DE AGARRAMENTO EM VALVULAS Posicionadoras

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • DIEGO RODRIGO CABRAL SILVA
  • VICENTE DELGADO MOREIRA
  • Data: Jan 31, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Com o advento de equipamentos de campo cada vez mais inteligentes e baratos, uma grande variedade de dados proveniente desses equipamentos pôde ser disponibilizada em tempo real para os sistemas supervisórios ou mesmo para outras aplicações. Assim, o grande desafio atual da engenharia é transformar essa grande quantidade de dados em informação útil à tomada de decisão, de modo que venha a contribuir efetivamente na melhoria da operação e planejamento do processo como um todo.

    Além disso, a detecção e o diagnóstico prematuro de uma falha, enquanto o processo ainda está operando em uma região controlável, pode ajudar a evitar um comportamento inesperado do sistema, que em última análise poderia ocasionar perdas bastante consideráveis como: paralização de processos, danos a equipamentos de custo elevado e principalmente, acidentes envolvendo vidas humanas, etc. O que se traduz, entre outras coisas, em perdas financeiras que podem chegar a valores bastante elevados, dependendo do tamanho e do setor da indústria em questão.

    Um problema muito comum nos processos industriais modernos é o agarramento, ou atrito estático, em válvulas posicionadoras. Recentemente, muitos estudos são desenvolvidos para tentar entender, modelar e detectar esse tipo de problema. Porém quantificar o agarramento ainda é um desafio. Uma vez que a posição da válvula (mv) é normalmente desconhecida em um processo industrial, o principal desafio é diagnosticar agarramento tendo conhecimento apenas dos sinais de saída do processo (pv) e o sinal de controle (op).

    É diante dessa realidade que este trabalho vem a contribuir com o estudo e análise de técnicas de detecção de falhas em válvulas posicionadoras. Neste trabalho é apresentada uma proposta baseada em Redes Neurais Artificiais para detectar e quantificar a quantidade de agarramento em válvulas utilizando apenas as informações de pv e op. São apresentados diferentes métodos para o pré-processamento do conjunto de treinamento da Rede Neural baseados no cálculo de Centroide e de Transformada de Fourier.

3
  • IVO ALVES DE OLIVEIRA NETO
  • DESENVOLVIMENTO DE UMA CADEIRA DE RODAS ROBÓTICA PARA TRANSPORTE DE PORTADOR DE NECESSIDADES ESPECIAIS

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • FILIPE DE OLIVEIRA QUINTAES
  • PABLO JAVIER ALSINA
  • Data: Jan 31, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • O objetivo da dissertação foi a realização da modelagem cinemática usando cadeias virtuais, que permitiu modelar a cadeira de rodas robótica como um conjunto de braços manipuladores cooperativos formando uma cadeia cinemática paralela. O desenvolvimento da cadeira de rodas robótica para transporte de portador de necessidades especiais que supera obstáculos como um degrau e barreiras existentes à acessibilidade em ruas e avenidas, incluindo o estudo sobre tecnologia assistiva, arquitetura paralela, modelagem cinemática, construção e montagem do protótipo do robô com a realização de uma lista de verificação de problemas e barreiras à acessibilidade em diversos percursos, tomando como base normas, decretos e leis existentes. Como resultado, foram realizadas simulações da cadeira em vários estados de operação para realizar a tarefa de subir e descer degrau com diferentes medidas, realizando o controle proporcional baseado na cinemática. Para comprovar os resultados simulados foi desenvolvido um protótipo do robô. Este projeto foi desenvolvido visando proporcionar uma melhor qualidade de vida às pessoas portadoras de necessidades especiais.

4
  • CARLOS ALBERTO DE ARAUJO PADILHA
  • Algoritmos Genéticos Aplicados a um Comitê de LS-SVM em Problemas de Classificação.

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANNE MAGALY DE PAULA CANUTO
  • JORGE DANTAS DE MELO
  • TERESA BERNARDA LUDERMIR
  • Data: Jan 31, 2013


  • Show Abstract
  • A classificação de padrões é uma das subáreas do aprendizado de máquina que possui o maior destaque. Entre as várias abordagens para resolver problemas de classificação de padrões, as Máquinas de Vetor de Suporte ( SVM ) recebem grande ênfase, devido a sua facilidade de uso e boa capacidade de generalização. A formulação por Mínimos Quadrados da SVM (LS-SVM) encontra um hiperplano de separação ótima através da solução de um sistema de equações lineares, evitando assim o uso da programação quadrática implementada na SVM. As LS-SVM fornecem alguns parâmetros livres que precisam ser corretamente selecionados para alcançar resultados satisfatórios em uma determinada tarefa. Apesar de possuir elevado desempenho, várias ferramentas têm sido desenvolvidas para aprimorá-lo, principalmente o desenvolvimento de novos métodos de classificação e a utilização de comitês de máquinas. Neste trabalho, nós propomos tanto o uso de um comitê de máquinas quanto o uso de um Algoritmo Genético (AG) para aprimorar o poder de classificação da LS-SVM. Na construção desse comitê, utilizamos uma seleção aleatória de subespaços de características do problema original, que divide o problema em subespaços onde cada classificador do comitê vai atuar. Então, aplicamos o AG para encontrar valores efetivos para os parâmetros de cada LS-SVM e também encontrando um vetor de pesos, medindo a importância de cada máquina na classificação final. Por fim, a classificação final é dada por uma combinação linear das respostas de cada máquina ponderadas pelos pesos. Foram utilizados vários problemas de classificação, tidos como benchmarks, para avaliar o desempenho do algoritmo e comparamos com outros classificadores.

5
  • DANILO CURVELO DE SOUZA
  • Sistema Especialista para Supressão Online de Alarmes em Processos Industriais

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DIEGO RODRIGO CABRAL SILVA
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MÁRIO CESAR MELLO MASSA DE CAMPOS
  • Data: Feb 1, 2013


  • Show Abstract
  • A operação de processos industriais vem se tornando mais complexa ao longo dos anos, e um dos elementos que possibilita este aumento de complexidade é a integração de novas tecnologias e soluções inteligentes empregadas na indústria, como é o caso dos sistemas de apoio à decisão.
     
    Neste sentido, este trabalho visa o desenvolvimento de um sistema de auxílio à operação baseado em uma ferramenta computacional chamada de sistema especialista. O objetivo principal é tornar a operação mais confiável e segura ao maximizar a quantidade de informações relevantes a cada situação através da utilização de um sistema especialista baseado em regras pré-moldadas para uma determinada área de conhecimento. Para a modelagem de tais regras foi proposto um ambiente de alto-nível, que permite a criação e manipulação de regras de forma facilitada através de programação visual. 
     
    A despeito de sua ampla gama de possíveis aplicações, esta dissertação tem como foco o contexto de filtragem em tempo real de alarmes durante a operação, devidamente validada em um estudo de caso baseado em um cenário real ocorrido em uma planta industrial de uma refinaria de petróleo e gás.
6
  • SUELIO FERNANDES CAROLINO
  • Regulador automático de tensão robusto utilizando técnicas de controle adaptativo
  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • ALEXANDRE CUNHA OLIVEIRA
  • ANDRES ORTIZ SALAZAR
  • FLAVIO BEZERRA COSTA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Feb 1, 2013


  • Show Abstract
  • A estabilidade de geradores síncronos conectados a rede elétrica tem sido objeto de estudo e investigações durante anos. O interesse por este assunto é justificado pelo fato de grande parte da energia elétrica produzida no mundo ser obtida com a utilização de geradores síncronos. Nesse aspecto, muitos trabalhos têm sido propostos utilizando técnicas de controle convencional e não convencional como lógica fuzzy, redes neurais e controladores adaptativos visando aumentar a margem de estabilidade do sistema quando ele está sujeito a falhas súbitas e distúrbios transitórios. Este trabalho apresenta uma estratégia de controle robusta não-convencional para a manutenção da estabilidadedos sistemas de potência e regulação da tensão de saída de geradores síncronos conectados à rede elétrica.
    A estratégia de controle utilizada é composta pela integração de uma superfície deslizante com um controlador linear. Esta estrutura de controle contribui para a prevenção dos sistemas de potência de perder o sincronismo após uma falha súbita e regulação da tensão terminal do gerador após a falta. A viabilidade da estratégia de controle proposta foi testada experimentalmente em um gerador síncrono de pólos salientes de 5 kVA em uma estrutura reduzida de laboratório. Resultados experimentais que comprovam a eficácia dessa estrutura de controle são apresentados.

7
  • ISAEL CALISTRATO JACOME
  • Controle Adaptativo por Modelo de Referência e Estrutura Variável no Caso
    Discreto no Tempo
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • SAMAHERNI MORAIS DIAS
  • DARLAN ALEXANDRIA FERNANDES
  • Data: Feb 5, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Com o avanço da tecnologia os sistemas embarcados utilizando técnicas adaptativas 
    estão sendo utilizados com mais frequência. Uma dessas técnicas é o Controlador Adaptativo
    por Modelo de Referência e Estrutura Variável (VSMRAC). A implementação dessa técnica em
    sistemas embarcados, requer a consideração do período de amostragem que se não for
    levado em consideração, pode afetar de maneira negativa o desempenho do sistema e até
    mesmo levá-lo à instabilização. Este trabalho propõe uma análise de estabilidade do VS-MRAC
    para o caso discreto no tempo para uma planta SISO linear, invariante no tempo, com grau
    relativo unitário. O objetivo é analisar a influência do período de amostragem no desempenho do
    sistema e a relação desse período com o fenômeno de "chattering" e instabilização do sistema.
8
  • WELLINGTON SILVA DE SOUZA
  • Superando os Riscos da Segurança baseada em Perímetro - Uma abordagem com Identificação Federada
     através de Certificados Digitais A3/ICP-Brasil e SAML
  • Advisor : SERGIO VIANNA FIALHO
  • COMMITTEE MEMBERS :
  • SERGIO VIANNA FIALHO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCOS CESAR MADRUGA ALVES PINHEIRO
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Feb 18, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Observa-se que na atualidade as redes corporativas de empresas e
    instituições se mostram completamente despreparadas ao lidar com ameaças
    advindas de novas tecnologias de comunicação, comportamento de risco de
    usuários, interoperabilidade com sistemas de terceiros e outsourcing. A
    visão tradicional de segurança baseada em perímetro (modelo do “castelo e
    fosso”), além de entravar a evolução dos sistemas corporativos, cria, tanto
    em administradores quanto usuários, a falsa ilusão de proteção. Para lidar
    com essa nova gama de ameaças, um novo paradigma orientado à segurança
    intrínseca dos dados, chamado "deperimetrização", começou a ser estudado na
    última década. No entanto, um mecanismo seguro e eficaz de identificação
    federada é um dos pré-requisitos para se alcançar o objetivo de uma rede
    sem fronteiras.
9
  • KENNEDY REURISON LOPES
  • Ambiente Virtual Colaborativo para Suporte à Operação
  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • JORGE DANTAS DE MELO
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • LEOCARLOS BEZERRA DA SILVA LIMA
  • Data: Feb 28, 2013


  • Show Abstract
  • Vem se tornando cada vez mais frequente o uso de mecanismos de comunicação remota em virtude dos avanços das tecnologias de informação e a falta de
    disponibilização de tempo dos especialistas nas atividades industriais. Pensando nisto, este trabalho tem por objetivo desenvolver uma plataforma de
    colaboração entre especialistas para solucionar problemas encontrados na indústria de petróleo e gás natural voltados para a planta simulada do vaso
    separador. O ambiente proposto consiste de um conjunto de ferramentas para troca de informações entre especialistas e a possível incorporação de
    módulos inteligentes ao sistema, permitindo a construção de facilidades computacionais e uma maior interação entre os especialistas mesmo que se
    encontrem em diferentes localizações geográficas.
    
10
  • ANA CAROLINA SALVADOR OURIQUE
  • ANÁLISE DE ANTENAS PARA APLICAÇÃO EM RASTREAMENTO DE ANIMAIS POR SATÉLITE

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • JEAN PAUL DUBUT
  • JOSÉ EDUARDO MANTOVANI
  • LAERCIO MARTINS DE MENDONCA
  • RONALDO DE ANDRADE MARTINS
  • SANDRO GONCALVES DA SILVA
  • Data: Mar 18, 2013


  • Show Abstract
  • A transmissão de dados via satélite possibilita o rastreio de animais durante períodos prolongados e sem a necessidade de recuperar os equipamentos, o que o torna ideal para estudos de longa distância principalmente em ambientes de difícil acesso. A análise destes dados permite determinar zonas utilizadas para alimentação, desenvolvimento e descanso do animal sob análise, informações essas, essenciais para seu estudo de conservação.

    Na caracterização deste problema, o sistema sofre uma forte influência dos parâmetros geoclimáticos do ambiente que deterioram grande parte o sinal transmitido, gerando perdas de informações enviadas. Assim, a análise dos parâmetros práticos do conjunto do transmissor de dados permite fazer alterações nos modelos de antenas  que podem aumentar o número de mensagens recebidas.

    O objetivo do presente estudo é analisar o comportamento e características teóricas do modelo padrão de antena utilizada na aplicação e comparar a outros modelos de antenas, todos para a faixa de 401MHz. Na realização deste trabalho foram realizados uma serie de experimentos, sob diferentes parâmetros geoclimáticas e modelamento computacional.

11
  • KAYO GONCALVES E SILVA
  • Análise de Escalabilidade de uma Implementação Paralela do Simulated Annealing Acoplado

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • DANIEL ALOISE
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • SIMONE DE LIMA MARTINS
  • Data: Mar 25, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • O presente trabalho analisa o desempenho paralelo de uma implementação do Simulated Annealing Acoplado (CSA, do inglês Coupled Simulated Annealing) para otimização de variáveis contínuas sem restrições. O processamento paralelo é uma forma eficiente de processamento de informação com ênfase na exploração de eventos simultâneos na execução de um software. Ele surge principalmente devido às elevadas exigências de desempenho computacional e à dificuldade em aumentar a velocidade de um único núcleo de processamento. Apesar das CPUs multiprocessadas, ou processadores multicore, serem facilmente encontrados atualmente, diversos algoritmos ainda não são adequados para executar em arquiteturas paralelas. No desenvolvimento de aplicações paralelas, é necessário, também, utilizar paralelismo dentro da tarefa. A implementação do CSA descrita no presente trabalho explora o real potencial desse tipo de paralelismo. O algoritmo do CSA é caracterizado por um grupo de otimizadores Simulated Annealing (SA) trabalhando em conjunto no refinamento da solução. Cada otimizador SA é executado em uma única thread, e essas executadas por diferentes processadores. Na análise de desempenho e escalabilidade paralela, as métricas investigadas foram: o tempo de execução; o speedup do algoritmo com respeito ao aumento do número de processadores; e a eficiência na utilização de elementos de processamento com relação ao aumento da instância do problema tratado. Além disso, foi verificado a qualidade da solução final. Para o estudo, esse trabalho analisa uma versão paralela do CSA e sua versão serial equivalente. Ambos algoritmos foram analisados sobre 14 funções de referência. Para cada uma dessas funções, o CSA é avaliado utilizando de 2 a 24 otimizadores. Os resultados obtidos são exibidos e comentados observando-se as métricas de análise. As conclusões do trabalho caracterizam o CSA como um bom algoritmo paralelo, seja na qualidade das soluções como na escalabilidade e eficiência paralela.

12
  • VICTOR LEONARDO CAVALCANTE MELO DA SILVA
  • Predição da Incrustação em um Trocador de Calor Baseada em Redes
    Neurais Artificiais

  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • JORGE DANTAS DE MELO
  • ADRIAO DUARTE DORIA NETO
  • MARCIA MARIA LIMA DUARTE
  • LAERTE DE MEDEIROS BARROS JUNIOR
  • Data: Apr 19, 2013


  • Show Abstract
  • Um problema sério que afeta unidades de refino de petróleo é a
    deposição e incrustação de sólidos nos equipamentos. Esses resíduos estão
    naturalmente presentes no petróleo ou são produtos de reações químicas
    durante o seu transporte. Um permutador de calor, quando sujo, perde sua
    capacidade de aquecer adequadamente o petróleo, precisando,
    periodicamente, ser desligado, para que possa ser realizada uma limpeza.
    Informações prévias de quando será necessário realizar as paradas podem
    melhorar a eficiência geral da planta. Esse trabalho desenvolveu um
    sistema de predição da incrustação em um permutador da Refinaria Potiguar
    Clara Camarão, com base em dados coletados em parceria com a Petrobras.
    Foram utilizadas redes neurais recorrentes que preveem a vazão no
    permutador em instantes futuros. Essa variável é o principal indicador da
    incrustação, pois seu valor diminui gradualmente ao longo do tempo devido
    a esse problema. A predição pode ser usada para dizer quando a vazão terá
    caído abaixo de um valor satisfatório, indicando quando será necessário
    parar o equipamento para limpeza.

13
  • ALMIR SOUZA E SILVA NETO
  • MÉTODO DINÂMICO APLICADO PARA ANTENAS CILÍNDRICAS

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • JOSE PATROCINIO DA SILVA
  • SANDRO GONCALVES DA SILVA
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Data: Jun 28, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Nos dias atuais observa-se um grande avanço na área aeroespacial, no que tange os lançamentos de foguetes para pesquisa, experimentos, sistema de telemetria, sensoriamento remoto, sistema de radar (rastreamento e monitoração), sistemas de comunicações via satélites e inserção de satélites em órbita.

    Em virtude disto, este trabalho estuda a aplicação de uma antena de microfita circular, tipo anel, na estrutura do foguete ou míssel para obter os dados de telemetria, operando na faixa de 2 a 4 GHz, na banda S. Uma das suas vantagens é a estrutura que facilita a transmissão e recepção de dados, resultando em um melhor aproveitamento do sinal.

    Este trabalho tem como objetivo principal a aplicação do Método de Linha de Transmissão Transversa – LTT às estruturas cilíndricas para a obtenção da frequência de ressonância complexa.

    As análises desenvolvidas neste trabalho utilizaram o Método da Linha de Transmissão Transversa que é um método de análise rigorosa no domínio espectral, para aplicação em foguetes e mísseis. Este analisa a propagação na direção “ρ”, transversa às interfaces dielétricas “z” e “φ”, para coordenadas cilíndricas, tendo assim as equações gerais dos campos eletromagnéticos em função de  e  [13].

    Vale ressaltar que para a obtenção das componentes dos campos elétricos e magnéticos em relação aos componentes transversais no Domínio da Transformada de Fourier – DTF são aplicadas as condições de contorno de acordo com a estrutura [13].

    Com a teoria desenvolvida foram utilizados recursos computacionais para obtenção dos cálculos numéricos, através do Fortran Power Station, Silab e o Wolfram Mathematica®. As simulações da estrutura apresentada foi feita através do programa HFSS™ (High Frequency Structural Simulator).

    O protótipo foi construído utilizando, como substrato, o ULTRALAM® 3850, da Rogers Corporation, e uma placa de alumínio como plano terra.

    A concordância entre os resultados desses e a simulada valida o processo estabelecido.

    São apresentadas sugestões e conclusões para a continuidade deste trabalho.
14
  • GLAUCO GEORGE CIPRIANO MANIÇOBA
  • Controle de Temperatura do Sistema de Refrigeração a Água de uma Tocha Plasmática Indutiva Utilizando Lógica Fuzzy

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ALBERTO SOTO LOCK
  • Data: Jul 5, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este projeto propõe desenvolver e implementar um controlador para o sistema de refrigeração da tocha indutiva a plasma térmico. Este processo é feito a partir da medição da temperatura através de um sensor do sistema de refrigeração. O sinal produzido será enviado para uma entrada analógica do microcontrolador da família PIC, que utilizando os conceitos de lógica fuzzy, controla a velocidade de um motor bomba. Este é responsável por diminuir ou aumentar o fluxo circulante de água que passa pela bobina, pelo corpo da tocha e pelo flange de fixação, deixando-os na temperatura desejada. A velocidade desta bomba será controlada a por um inversor de frequência. O microcontrolador, também, acionará um ventilador caso exceda a temperatura de referência.  

     

    A proposta inicial foi o desenvolvimento do controle da temperatura da bobina de uma tocha indutiva a plasma, mas com algumas adequações, foi possível também aplicar no corpo da tocha. Essa tocha será utilizada em uma planta de tratamento de resíduos industriais e efluentes petroquímicos. O controle proposto visa garantir as condições físicas necessárias para tocha de plasma, mantendo a temperatura da água em um determinado nível que permita o resfriamento sem comprometer, no entanto, o rendimento do sistema.

     

    No projeto será utilizada uma tocha de plasma com acoplamento indutivo (ICPT), por ter a vantagem de não possuir eletrodos metálicos internos sendo erodidos pelo jato de plasma, evitando uma possível contaminação, e também devido à possibilidade do reaproveitamento energético através da cogeração de energia.  

     O desenvolvimento da tecnologia a plasma na indústria de tratamento de resíduos vem obtendo grandes resultados. Aplicações com essa tecnologia têm se tornado cada vez mais importantes por reduzir, em muitos casos, a produção de resíduos e o consumo de energia em vários processos industriais.

15
  • CECÍLIO MARTINS DE SOUSA NETO
  • Estabilizador de Sistema de Potência para Máquinas Síncronas de Polos Salientes utilizando a Transformada Wavelet

  • Advisor : FLAVIO BEZERRA COSTA
  • COMMITTEE MEMBERS :
  • FLAVIO BEZERRA COSTA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • ALEXANDRE CUNHA OLIVEIRA
  • Data: Jul 5, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Os estabilizadores de sistemas de potência são empregados para suprimir oscilações eletromecânicas, de baixa frequência, e estender os limites de estabilidade de geradores síncronos. Propõe-se nesta dissertação de mestrado um estabilizador de sistema de potência baseado nas wavelets, composta por uma nova metodologia para extração e compensação de oscilações eletromecânicas em sistemas elétricos de potência baseado nas energias dos coeficientes de aproximação da transformada wavelet discreta redundante, com o objetivo de reduzir os efeitos de atraso e atenuações dos estabilizadores de sistemas de potência convencionais. Por outro lado, as energias dos coeficientes wavelet são utilizadas para detecção das oscilações elétricas e habilitação do estabilizador de sistema de potência proposto apenas nas situações de falta. A eficácia do desempenho do estabilizador de sistema de potência proposto foi comprovada por meio de resultados experimentais, cujo desempenho foi comparado com o desempenho do estabilizador de sistema de potência convencional. Além disso, os efeitos das wavelets mães também foram avaliados. 

16
  • ALBANISA FELIPE DOS SANTOS
  • Desenvolvimento Teórico e Experimental de FSSs com Elementos Fractais de Gosper em Estruturas de Multicamadas

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • GLÁUCIO LIMA SIQUEIRA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Jul 25, 2013


  • Show Abstract
  • Neste trabalho, as propriedades de auto-similaridade dos fractais são exploradas para o desenvolvimento de superfícies seletivas de frequência (Frequency Selectives Surfaces - FSS) com várias bandas de rejeição. Em particular, são considerados fractais de Gosper, na definição dos formatos dos elementos das FSS. Por conta da dificuldade de impressão de detalhes dos elementos das FSS, são considerados apenas elementos pré-fractais, com até três iterações fractais. As simulações foram realizadas com o uso do programa comercial Ansoft Designer. Para fins de validação de resultados, foram construídos vários protótipos de FSS com elementos pré-fractais. No processo de fabricação, os formatos dos elementos pré-fractais foram desenhados com auxílio do programa Corel Draw. Os protótipos construídos foram medidos através de um analisador de redes vetorial (modelo N3250A, da Agilent Technologies). A utilização de elementos pré-fractais nas estruturas de FSS consideradas, permitiu verificar que o aumento do nível fractal possibilita a redução do tamanho dos elementos, porém reduz a largura de banda das mesmas. Neste sentido, é também investigado o efeito produzido pelo cascateamento de estruturas de FSS na largura de banda. Foi observado que o uso de estruturas cascateadas, além de aumentar a largura de banda, permitiu, em alguns casos, a obtenção de até respostas em frequência com três bandas de operação entre 6 GHz e 15 GHz.

17
  • SARAH THOMAZ DE SA ROSSITER
  • Ambiente de Desenvolvimento Web Multiplataforma Configurável para Robótica Educacional

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • RAFAEL VIDAL AROCA
  • FELIPE MAIA GALVÃO FRANÇA
  • Data: Jul 25, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Propomos um ambiente de desenvolvimento online autoconfigurável, desenvolvido especificamente para aplicações em robótica educacional. O ambiente, que surge como uma extensão do software RoboEduc, possibilita que a programação de diversos Robôs programáveis possa ser realizada na linguagem R-Educ. Tornamos possível que o usuário programe na linguagem R-Educ e o seu código seja convertido para uma linguagem cadastrada anteriormente, compilado e em seguida enviado ou executado pelo robô. Para o desenvolvimento deste trabalho, realizamos inicialmente uma pesquisa bibliográfica acerca das principais linguagens de programação utilizadas em robótica, bem como suas definições e paradigmas, a partir da qual foi possível definir um conjunto de padrões considerados importantes para a criação deste ambiente. Em seguida, na fase de desenvolvimento de software, foi implementado o ambiente de desenvolvimento, levando em consideração os requisitos e funcionalidades definidos na fase de projeto. Por fim, para validar a plataforma, realizaremos alguns cadastros de linguagens de programação e verificaremos se o ciclo completo foi satisfeito - cadastro de linguagem, programação em R-Educ, compilação para a linguagem cadastrada, compilação para o código de máquina e envio do código para o robô.

18
  • DIEGO RAMALHO MINERVINO
  • DESENVOLVIMENTO DE ESTRUTURAS INTEGRADAS DE FILTROS E ANTENAS PARA APLICAÇÕES EM SISTEMAS DE COMUNICAÇÕES SEM FIO

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Jul 26, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho apresenta um estudo da integração de filtros e antenas de microfita, originando os dispositivos denominados como filtennas, para aplicações em sistemas de comunicações sem fio. A concepção destas estruturas se deu a partir da observação de filtennas baseadas na integração entre antenas cornetas e superfícies seletivas de frequência (FSS), usadas na banda X. A opção por estruturas de linhas de microfita para o desenvolvimento de uma nova configuração de filtennas se justifica pela larga aplicação dessas linhas de transmissão, nas últimas décadas, resultando sempre na fabricação de circuitos planares com estruturas leves, de dimensões reduzidas, de baixo custo, fáceis de construir e, principalmente, fáceis de integrar com outros dispositivos e circuitos de micro-ondas. Além disso, a estrutura de antena considerada para a composição das filtennas consiste de um monopolo planar de microfita com a integração de filtros de microfita na linha de alimentação da antena. Em particular, são considerados monopolos elípticos de microfita (que operam em banda ultralarga, UWB) e filtros de microfita (em estruturas com seções associadas em série e/ou acopladas).  Além disso, o monopolo de microfita apresenta uma largura de banda adequada e um diagrama de radiação omnidirecional, de tal forma que a sua integração com filtros de microfita resulta na redução da largura de banda, porém com pequenas alterações no diagrama de radiação. Os métodos matemáticos usados na análise dos monopolos, filtros e filtennas foram os dos elementos finitos e dos momentos, através da utilização dos softwares comerciais Ansoft Designer e Ansoft HFSS, respectivamente. Especificamente, são analisadas as características principais das filtennas, tais como: diagrama de radiação, ganho e largura de banda. Foram projetadas, construídas e medidas, diversas estruturas de filtennas, para fins de validação dos resultados simulados. Também foram utilizadas ferramentas computacionais (do tipo CAD) no processo de construção de protótipos dos monopolos planares, dos filtros e das filtennas. Esses protótipos foram construídos sobre substratos de fibra de vidro, referenciados como FR4, com altura, h, igual a 1,57 mm e permissividade relativa, εr , igual a 4,4. As medições foram realizadas com um analisador de redes (modelo FSH-Z3, da Rohde&Schwarz), no Laboratório de Telecomunicações da UFRN. As comparações entre os resultados simulados e medidos foram efetuadas com o uso do programa Matlab (Matrix Laboratory), sendo observada uma boa concordância entre os mesmos.

19
  • AYLANNA RAQUEL DA COSTA OLIVEIRA
  • Uso de Funções de Alívio para estimar o efeito de Chaveamentos Corretivos na eliminação de congestionamentos em Sistemas de Potência


  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE LUIZ DA SILVA JUNIOR
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Jul 26, 2013


  • Show Abstract
  • Em sistemas desregulamentados, a Gestão de Congestionamentos é uma das principais tarefas executadas pelos operadores do sistema de transmissão para garantir o estado seguro da rede. Para resolver este problema, várias estratégias de controle são utilizadas. Dentre elas, destaca-se a técnica de chaveamentos corretivos, devido ao seu baixo custo de implantação e à velocidade do tempo de convergência das soluções obtidas através do uso da metodologia de linearização de cálculos de fluxos de carga, conhecida como Injeção Reversa. Dessa forma, este trabalho tem como objetivo desenvolver um algoritmo determinístico que se proponha a eliminar congestionamentos em Sistemas de Potência por meio de Funções de Alívio, para estimar o efeito das variantes de chaveamento úteis da rede. Através desse método, pretende-se que a abordagem apresentada obtenha um menor custo computacional, de forma que ela permita aplicações de estudo em tempo real.

20
  • VALDEMIR PRAXEDES DA SILVA NETO
  • CARACTERIZAÇAO DE CIRCUITOS PLANARES DE MICRO-ONDAS PELO MÉTODO ITERATIVO DAS ONDAS

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ADAILDO GOMES D ASSUNCAO JUNIOR
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • MURILO ARAUJO ROMERO
  • Data: Jul 26, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Os circuitos planares são estruturas que atraem cada vez mais a atenção dos pesquisadores, tanto pelo bom desempenho como pelo alto grau de integração com outros dispositivos, na prototipagem de sistemas de transmissão e recepção de sinais na faixa de micro-ondas. Neste contexto, o desenvolvimento de novas técnicas de análise desses dispositivos tem contribuído de forma significativa para a concepção de estruturas planares com desempenhos excelentes e alto grau de confiabilidade. Neste trabalho, um método de onda completa, baseado no conceito de ondas eletromagnéticas e no princípio da reflexão e transmissão dessas ondas em uma interface, o Wave Concept Iterative Procedure (WCIP), é descrito como uma ferramenta com um alto grau de precisão na análise de circuitos planares de microondas. A aplicação do método proposto é exemplificada com a caracterização de filtros planares, antenas de microfita e superfícies seletivas de frequência. Em alguns casos, foram construídos protótipos destes dispositivos e os resultados medidos foram comparados com os resultados simulados obtidos através do modelo matemático proposto. Além disso, os resultados simulados deste trabalho também foram comparados com os resultados obtidos através de simulações efetuadas com softwares comerciais. As comparações efetuadas mostram que existe uma boa concordância entre os resultados obtidos através do método WCIP, os resultados calculados através de softwares comerciais e os resultados medidos, confirmando a precisão do método de análise proposto.

21
  • AMANDA DANIELLE OLIVEIRA DA SILVA DANTAS
  • IDENTIFICAÇÃO DE MODELOS POLINOMIAIS NARX UTILIZANDO ALGORITMOS COMBINADOS DE DETECÇÃO DE ESTRUTURA E ESTIMAÇÃO DE PARÂMETROS COM APLICAÇÕES PRÁTICAS

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • LUÍS FERNANDO ALVES PEREIRA
  • OSCAR GABRIEL FILHO
  • Data: Jul 26, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • A modelagem de processos industriais tem auxiliado na produção e minimização dos custos permitindo a previsão do comportamento dos sistemas, supervisão de processos e projeto de controladores. A partir dos benefícios proporcionados pela modelagem, objetiva-se primeiramente, nesta dissertação, apresentar uma metodologia de identificação de modelos não-lineares com estrutura NARX, a partir da implementação de algoritmos combinados de detecção de estrutura e estimação de parâmetros. Inicialmente será ressaltada a importância da identificação de sistemas na otimização de processos industriais, especificamente a escolha do modelo para representar adequadamente as dinâmicas do sistema. Em seguida, é apresentada uma breve revisão das etapas que compõem a identificação de sistemas. Na sequência, são apresentados os métodos fundamentais para detecção de estrutura (Modificado Gram- Schmidt) e estimação de parâmetros (Método dos mínimos quadrados e Método dos mínimos quadrados estendido) de modelos. No trabalho é também realizada, através dos algoritmos implementados, a identificação de dois processos industriais distintos representados por planta de nível didática, que possibilita o controle de nível e vazão, e uma planta de processamento primário de petróleo, que tem como objetivo realizar o tratamento primário do petróleo em plataformas petrolíferas. A dissertação é finalizada com uma avaliação dos desempenhos dos modelos obtidos, quando comparados com o sistema. A partir desta avaliação será possível observar se os modelos identificados são capazes de representar as características estáticas e dinâmicas do sistema, e assim possibilitar a escolha do modelo mais apropriado para descrever os sistemas utilizados no desenvolvimento desta dissertação.



22
  • LEONARDO ENZO BRITO DA SILVA
  • Contribuições a técnicas de agrupamento e visualização de dados multivariados utilizando mapas auto-organizáveis

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • ALLAN DE MEDEIROS MARTINS
  • FLAVIUS DA LUZ E GORGONIO
  • SARAJANE MARQUES PERES
  • Data: Jul 29, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Os mapas auto-organizáveis (SOM) são redes neurais artificiais amplamente utilizadas no campo da mineração de dados, principalmente por se constituírem numa técnica de redução de dimensionalidade dada a grade fixa de protótipos associados à rede. A fim de particionar e visualizar adequadamente a rede SOM, os diversos métodos existentes na literatura devem ser aplicados em uma etapa de pós-processamento nos seus protótipos, visando inferir características relevantes do conjunto de dados. Em geral, tal processamento efetuado sobre os protótipos da rede, ao invés do conjunto de dados em sua totalidade, reduz o custo computacional, dada a quantização vetorial.

    Este trabalho propõe pós-processamentos dos protótipos da rede SOM no espaços de entrada e saída, aliando técnicas de visualização a algoritmos baseados na força gravitacional e na procura do menor caminho com maior recompensa. Tais métodos levam em consideração forças de ligação entre neurônios vizinhos e características de distâncias e densidade de padrões, ambas associadas a posição que o neurônio ocupa no espaço dos dados após o treinamento da rede. Dessa forma, busca-se definir mais nitidamente a disposição dos agrupamentos presentes nos dados. Experimentos foram realizados para avaliar os métodos propostos utilizando diversos conjuntos de dados gerados artificialmente, assim como do mundo real.

23
  • EDSON ANIBAL DE MACEDO REIS BATISTA
  • Estudo da topologia de redes de conexão funcional no córtex sensorial primário e hipocampo durante o sono de ondas lentas

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • ALLAN DE MEDEIROS MARTINS
  • SIDARTA TOLLENDAL GOMES RIBEIRO
  • NIVALDO ANTONIO PORTELA DE VASCONCELOS
  • ODEMIR MARTINEZ BRUNO
  • Data: Jul 30, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • A análise da topologia de redes é uma poderosa ferramenta no estudo de sistemas
    complexos tal como as redes cerebrais. Este trabalho procura descrever as mudanças na
    topologia de redes de conexão funcional em neurônios do córtex sensorial e do hipocampo
    durante o sono de ondas lentas (SWS) em animais expostos à novidade. O sono de ondas
    lentas é um importante estado do sono onde há reverberação de padrões de atividade
    elétrica ocorridos na vigília, tendo com isso papel fundamental na consolidação de memória.
    Apesar de sua importância ainda não há estudos que caracterizam a dinâmica da
    topologia de redes de conexão funcional durante este estado. Tão pouco há estudos que
    descrevem as modificações topológicas que a exposição à novidade traz a essas redes.
    Observamos que várias propriedades topológicas são modificadas após a exposição à novidade
    e que tais modificações se mantêm por um longo período de tempo. A maior parte
    das propriedades modificadas pela exposição à novidade está relacionada à tolerância à
    falha.

24
  • ALESSANDRO VINÍCIUS PEREIRA ROLIM DE ARAÚJO
  • Metodologia para o ensino de Física usando robótica de baixo custo

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • ALBERTO SIGNORETTI
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL VIDAL AROCA
  • Data: Jul 31, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como propósito apresentar uma metodologia baseada na teoria socio-interacionista de Lev Vygotky, através de atividades investigativas, que integra o ensino de Física com a robótica, direcionadas para alunos do curso de licenciatura em Física, na busca de fornecer mais uma capacitação para os futuros professores. Organizada por meio de oficinas de robótica pedagógicas que abordam conceitos de físicas através da utilização do kit didático com robótica de baixo custo proposto juntamente com atividades produzidas, a metodologia foi apresenta e discutida, e posteriormente, colocada em prática nas oficinas para que esses futuros professores possam levar a robótica para sua sala de aula. Participaram alunos do último e do penúltimo período da Licenciatura em Física do Instituo Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte, câmpus Caicó.

25
  • MILTON MEDEIROS DA SILVA
  • Controle de Posição de uma Plataforma Plana Para Captação de Irradiação Solar

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ARIEL AIRES DO NASCIMENTO
  • Data: Aug 6, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho objetiva o projeto, o desenvolvimento e a avaliação de desempenho de uma plataforma plana com dois graus de liberdade para captação da radiação solar. São apresentados o projeto e a implementação de um sistema fuzzy para o controle eficiente do movimento de rastreamento solar da plataforma.  

26
  • AUGUSTO CESAR FIALHO WANDERLEY
  • Perspectivas de Inserção da Energia Solar Fotovoltaica na Matriz Energética do Rio Grande do Norte

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • FILIPE DE OLIVEIRA QUINTAES
  • LUIZ GUILHERME MEIRA DE SOUZA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • Data: Aug 30, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • A geração de energia elétrica no Brasil é predominantemente renovável, com a geração interna hidráulica sendo superior a 74% do total de sua matriz energética. O racionamento de energia elétrica ocorrido em 2001, devido à falta de chuvas, levou o país a incrementar a participação de fontes alternativas de energia. Esta necessidade por novas fontes de energia faz com que as potencialidades regionais sejam aproveitadas, o que configura a mudança do modelo de geração, passando de geração centralizada para geração distribuída. Dentre as fontes alternativas de energia, a solar apresenta-se como uma fonte bastante promissora para o Brasil, tendo em vista que a maior parte do seu território está localizada próximo à linha do equador, o que acarreta em um dia de maior duração solar. O estado do Rio Grande do Norte tem um dos maiores índices de incidência solar do território brasileiro, o que o torna apto a receber investimentos para a instalação de usinas solares fotovoltaicas. Esta dissertação apresentará o estado da arte em geração de energia solar fotovoltaica e analisará o potencial de geração da energia solar fotovoltaica no RN através de medições solarimétricas realizadas em Natal, capital do estado.

27
  • DANIEL WANDERLEY HONDA
  • Controlador Adaptativo por Posicionamento de Polos e Estrutura Variável Aplicado ao Controle de Geradores Eólicos Baseados em Máquina de Indução Duplamente Alimentada

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • FABIANO SALVADORI
  • RICARDO FERREIRA PINHEIRO
  • SAMAHERNI MORAIS DIAS
  • Data: Sep 13, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • As fontes de energias renováveis têm, na última década, ganho uma grande propulsão em todo o mundo devido aos mais diversos fatores: políticos, ambientais, financeiros, entre outros. Dentro deste universo, temos, em especial, a energia obtida através do vento - energia eólica - que tem se destacado com um crescimento vertiginoso nos últimos anos, inclusive no Brasil, principalmente na região Nordeste, devido ao seu custo-benefício entre as energias "limpas". Neste cenário, propõe-se a comparação do controlador por posicionamento de polos e estrutura variável (VS-APPC) com o controlador proporcional integral (PI) aplicados em um sistema de conversão de energia eólica que utiliza um gerador de indução duplamente alimentado (Double-Fed Induction Generator - DFIG). Testes de robustez e desempenho foram realizados com incertezas nos parâmetros da máquina e variações de referência de velocidade.

28
  • ANDERSON BRAULIO NOBREGA DA SILVA
  • Um modelo de unidade de medida inercial utilizando três acelerômetros triaxiais

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • FRANCISCO DAS CHAGAS MOTA
  • PABLO JAVIER ALSINA
  • FABIANO FRAGOSO COSTA
  • Data: Oct 7, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • No espaço tridimensional, um corpo rígido qualquer pode efetuar translações e ou rotações em relação a cada um de seus eixos. Identificar com precisão o deslocamento realizado é fundamental para alguns tipos de sistemas em engenharia. Em sistemas de navegação inercial tradicionais, utilizam-se acelerômetros para reconhecer a aceleração linear e giroscópios para reconhecer a velocidade angular registrada durante o deslocamento. O giroscópio, entretanto, é um dispositivo de custo mais elevado e com alto consumo de energia quando comparado a um acelerômetro. Essa desvantagem deu origem às pesquisas a respeito de sistemas e unidades de medidas inerciais que não utilizam giroscópios. A ideia de utilizar apenas acelerômetros para calcular o movimento linear a angular surgiu no início da década de 60 e vem se desenvolvendo através de modelos que variam no número de sensores, na maneira como estes são organizados e no modelo matemático que é utilizado para derivar o movimento do corpo. Esse trabalho propõe um esquema para construção de uma unidade de medida inercial que utiliza apenas os sinais de três acelerômetros triaxiais para identificar o deslocamento do corpo. A proposta sugere que os sensores sejam montados e distribuídos em um mesmo plano de um sistema de coordenadas, facilitando a configuração destes dispositivos e consequente construção de um equipamento capaz de medir o deslocamento de um corpo rígido. A instalação dos sensores de aceleração no mesmo plano possibilita a implantação dos dispositivos em uma única placa de circuito integrado.
29
  • ANTONIO WALLACE ANTUNES SOARES
  • PROJETO EM FPGA DE UM CONTROLADOR UNIFICADO PARA CORREÇÃO DE FATOR DE POTÊNCIA COM RETIFICADORES BOOST BIDIRECIONAIS MONOFÁSICOS

  • Advisor : ALUIZIO ALVES DE MELO BENTO
  • COMMITTEE MEMBERS :
  • ALUIZIO ALVES DE MELO BENTO
  • VALENTIN OBAC RODA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • PAULO PEIXOTO PRAÇA
  • Data: Dec 18, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • A utilização de FPGA (Field Programmable Gate Array) para o desenvolvimento de estratégias de controle digital para aplicações em eletrônica de potência tem despertado um crescente interesse entre muitos pesquisadores. Tal interesse se deve as grandes vantagens apresentadas pela FPGA, que incluem: menor esforço de projeto, alto desempenho e grande flexibilidade de prototipagem. Este trabalho propõe o desenvolvimento e implementação de um controlador unificado, mediante o uso de FPGA, utilizando a técnica de controle de um ciclo (One-Cycle Control Technique) para correção de fator de potência com retificadores boost. Este controlador pode ser aplicado a um total de doze conversores, sendo seis inversores e seis retificadores definidos pela topologia e pelo tipo de modulação de tensão: (1) ponte completa com modulação bipolar de tensão (MBT), (2), com modulação unipolar de tensão (MUT) e (3) com modulação com grampeamento de tensão (MGT); (4) ponte completa intercalada com MGT; (5) meia ponte com MBT; e (6) meia ponte intercalada com MBT. O projeto é desenvolvido e prototipado utilizando as ferramentas Matlab®/Simulink em conjunto com a biblioteca DSP Builder, disponibilizada pela Altera®. O controlador proposto será validado com resultados de simulação e experimentais.

Thesis
1
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • Uma Metodologia para Modelagem e Avaliação da Dependabilidade de Redes Industriais Sem Fio
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DANIEL ALOISE
  • FRANCISCO VASQUES
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • PAULO JOSÉ LOPES MACHADO PORTUGAL
  • PAULO ROMERO MARTINS MACIEL
  • Data: Jan 21, 2013


  • Show Abstract
  • Garantir os requisitos de dependabilidade é fundamental para as aplicações industriais,
    onde falhas podem conduzir a defeitos cujas consequências impactam em prejuízos
    econômicos e principalmente danos ambientais e riscos aos operadores. Assim, diante da
    relevância do tema, esta tese propõem uma metodologia para análise da dependabilidade
    de redes industriais sem fio (WirelessHART, ISA100.11a, WIA-PA) ainda na fase de projeto.
    Entretanto, a proposta pode ser facilmente estendida para as fases de manutenção
    e expansão da rede. A proposta utiliza a teoria de grafos e o formalismo de Árvores de
    Falhas para criar automaticamente um modelo analítico a partir de uma dada topologia de
    rede industrial sem fio, onde a dependabilidade possa ser avaliada. As métricas de avaliação
    suportadas compreendem confiabilidade, disponibilidade e MTTF da rede, como
    também medidas de importância dos dispositivos, aspectos de redundância e defeitos em
    modo comum. Ressalta-se que a proposta independe de qualquer ferramenta para analisar
    quantitativamente as métricas visadas. Contudo, para propósito de validação da proposta
    utilizou-se uma ferramenta amplamente aceita na academia para esse fim (SHARPE). Adicionalmente,
    um algoritmo para geração dos cortes mínimos originalmente aplicado na
    teoria de grafos foi adaptado para o formalismo das Árvores de Falhas com o objetivo de
    garantir escalabilidade da metodologia às redes industriais sem fio (< 100 dispositivos).
    Finalmente, a metodologia proposta foi validada a partir de cenários típicos encontrados
    em ambientes industriais, como topologias estrela, linha, cluster e mesh. Foram também
    avaliados cenários com defeitos em modo comum e um conjunto de políticas a serem
    seguidas na criação de uma rede industrial sem fio. Para garantir aspectos de escalabilidade,
    uma análise de desempenho foi conduzida, onde pode-se observar a aplicabilidade
    da metodologia para as redes tipicamente encontradas em ambientes industriais.
2
  • TANIA LUNA LAURA
  • Sistema de Supervisão Aérea baseado em Navegação Visual para Detecção de Anomalias em Instalações de Petróleo e Gás

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • ANDRE MACEDO SANTANA
  • CRISTIANE CORRÊA PAIM
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Feb 1, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho trata do desenvolvimento de um protótipo de um helicóptero quadrirrotor para aplicações de monitoramento de instalações petrolíferas. Problemas de detecção de anomalias podem ser resolvidas através de missões de monitoramento executadas pelo quadrirrotor devidamente instrumentado, ou seja, sensores termo-infravermelhos devem ser embarcados. Este sistema de monitoramento proposto, visa reduzir acidentes de trabalho bem como tornar possível o uso de técnicas não destrutivas para detecção e localização de vazamentos causados por corrosões. Com este fim, a implementação de um protótipo, sua estabilização e uma estratégia de navegação foram propostas. O protótipo construído tem alta capacidade de carga e sua estratégia de controle baseia-se na divisão do problema de controle em dois níveis hierárquicos: o nível inferior estabiliza os ângulos e a altitude do veículo em valores desejados, enquanto o nível superior encarrega-se de fornecer referências adequadas para o nível inferior, assim, o quadrirrotor deve executar movimentos desejados. Arquiteturas de hardware e software foram especialmente desenvolvidas e implementadas para este protótipo. A estratégia de navegação em ambientes tridimensionais 3D para um helicóptero quadrirrotor é feita utilizando informações fornecidas por um sistema de aquisição de imagens (câmera monocular) embarcada no helicóptero. Considerando que o controle de nível inferior tenha sido resolvido, a técnica de navegação baseada em visão proposta trata o problema como estratégias de controle em alto nível (controle de posição relativa, geração de trajetória e seguimento de trajetória). Para o controle de posição utiliza-se uma técnica de controle por servovisão baseado
    em caracterísiticas de imagem. Assim, é necessário a extração de características no plano de imagem para controlar os movimentos do helicóptero. A geração de trajetória é feita num passo off-line, a qual é uma trajetória visual composta de características de imagem, especificamente, coordenadas do descritor SURF. Já para o seguimento de trajetórias é proposto uma estratégia de controle por sevovisão contínuo, possibilitando assim, uma estratégia de navegação local sem precisar de mapas métricos. Resultados experimentais e em simulação são apresentados para validar a proposta.

3
  • ARMANDO SANCA SANCA
  • Modelagem e Controle de Um Microveículo Aereo Multirotor: Uma Aplicação de Estabilidade Robusta com a Tecnica Backstepping em Uma Estrutura Hexa-rotor

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • ANDRE MACEDO SANTANA
  • ANFRANSERAI MORAIS DIAS
  • CARLOS EDUARDO TRABUCO DOREA
  • JÉS DE JESUS FIAIS CERQUEIRA
  • PABLO JAVIER ALSINA
  • Data: Feb 1, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Nesta tese, são apresentadas dois modelos dinâmicos de um VANT multirotor com capacidade de decolagem vertical e pouso considerando-se entradas não-lineares conjuntamente com o controlador robusto por backstepping. Os modelos dinâmicos são expressos usando-se as leis de Newton-Euler. Os modelos visam obtenção de uma melhor representação matemática do sistema mecânico para a análise e o projeto de controle, não apenas quando está pairando, mas também de decolagem, de pouso, ou de voo executando uma tarefa. As não linearidades de entrada são a zona-morta e a saturação, onde o efeito gravitacional e as inerentes restrições físicas dos rotores são relacionadas e abordadas. O hexa-rotor experimental está equipado com uma IMU/Ultrassom, que instrumentadas devidamente fornecem as medidas da atitude e altitude para o hexa-rotor. Os sensores foram modelados como o valor real, que ´e o valor ideal com a adição de um viés e mais um ruído branco desconhecidos e limitados. Os controladores de atitude e altitude foram derivadas usando a técnica de estabilidade robusta prática que lida com a convergência e estabilidade dentro de uma região com raio não nula, considerando-se algumas suposições e tratando as incertezas nas medições. A técnica de análise de Lyapunov foi usada para provar a estabilidade do sistema em malha fechada, calcular os limites dos ganhos de controle e a garantia limitada pretendida sobre o erro de seguimento da dinâmica da atitude na presença de distúrbios nas medições. As leis de controle foram testadas em simulações numéricas e em um hexa-rotor experimental, desenvolvido no Laboratório de Robótica da UFRN.

4
  • DANIEL SABINO AMORIM DE ARAUJO
  •  

    Análise de Agrupamentos Com Base na Teoria da Informação: Uma Abordagem  Representativa

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • JORGE DANTAS DE MELO
  • ANNE MAGALY DE PAULA CANUTO
  • ANTONIO DE PADUA BRAGA
  • MARLEY MARIA BERNARDES REBUZZI VELLASCO
  • Data: Mar 18, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Atualmente, um dos maiores desafios para o campo de mineração de dados é realizar a análise de agrupamentos em dados complexos. Diversas técnicas foram propostas mas, em geral, elas só conseguem atingir bons resultados dentro de domínios específicos, não existindo, dessa maneira, um consenso de qual seria a melhor maneira de se agrupar dados. Em geral, essas técnicas falham por fazer suposições nem sempre verdadeiras sobre a distribuição de probabilidade dos dados. Com base nisso, o trabalho proposto neste documento cria uma nova medida baseada no Potencial de Informação Cruzado que utiliza pontos representativos do conjunto de dados e a estatística extraída diretamente deles para medir a interação entre grupos. A abordagem proposta permite usar todas as vantagens desse descritor de informação e contorna as limitações impostas a ele pela sua própria forma de funcionamento. A partir disso, duas funções custo e três algoritmos de foram propostos para realizar a análise de agrupamentos. Como o uso de teoria da informação permite capturar a relação entre diferentes padrões, independentemente de suposições sobre a natureza dessa relação, a abordagem proposta aqui foi capaz de obter um desempenho superior aos principais algoritmos citados na literatura. Esses resultados valem tanto para o contexto de dados sintéticos desenvolvidos para testar os algoritmos em situações específicas quanto em dados extraídos de problemas reais de diferentes naturezas

5
  • CLARISSA DE LUCENA NOBREGA
  • ANÁLISE E PROJETO DE SUPERFÍCIES SELETIVAS DE FREQUÊNCIA COM ELEMENTOS PRÉ-FRACTAIS PARA APLICAÇÕES EM COMUNICAÇÕES INDOOR


  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • GLÁUCIO LIMA SIQUEIRA
  • MARCOS TAVARES DE MELO
  • PAULO HENRIQUE DA FONSECA SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Apr 9, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Nesta Tese, uma superfície seletiva de frequência (FSS) consiste de uma estrutura periódica bidimensional montada sobre um substrato dielétrico, que é capaz de selecionar sinais em uma ou mais faixas de frequências de interesse. Em busca da obtenção de um melhor desempenho, dimensões mais compactas, baixo custo de fabricação, entre outras características, estas estruturas periódicas têm sido continuamente otimizadas ao longo do tempo. Devido às suas características espectrais, que são similares as de filtros rejeita-faixa ou passa-faixa, as FSSs têm sido estudadas e usadas em aplicações diversas por mais de quatro décadas. O projeto de uma FSS com uma estrutura periódica composta de elementos pré-fractais facilita a sintonia destes filtros espaciais e o ajuste de seus parâmetros eletromagnéticos, possibilitando uma construção compacta, que, em geral, apresenta uma resposta estável em frequência e desempenho superior em relação à sua contrapartida Euclidiana. As propriedades únicas dos fractais geométricos têm-se mostrado bastante úteis, principalmente para a construção de antenas e superfícies seletivas de frequência, permitindo soluções inovadoras e aplicações comerciais na faixa de micro-ondas. Em aplicações mais recentes, as FSSs modificam os ambientes de propagação indoor (conceito emergente chamado de “wireless building”). Neste contexto, o uso de elementos pré-fractais também tem apresentado resultados promissores, tornando mais efetiva a filtragem de mais de uma faixa de frequências com uma estrutura de camada simples. Esta Tese aborda o projeto de FSSs com elementos pré-fractais baseados nas geometrias de Vicsek, Peano e dos terágonos, que funcionam como filtros espaciais do tipo rejeita-faixa. As propriedades de transmissão das superfícies periódicas são analisadas para a concepção de dispositivos eficientes, compactos e com respostas estáveis em frequência, aplicáveis na faixa de micro-ondas e adequados para utilizações em comunicações indoor. Os resultados teóricos e experimentais são discutidos em termos do efeito eletromagnético decorrente da variação de parâmetros como, número de iterações fractais (ou nível do fractal), fator de escala, dimensão fractal e periodicidade da FSS, de acordo com o elemento pré-fractal utilizado. A análise da influência da dimensão fractal sobre as propriedades de ressonância de uma FSS é uma contribuição nova no que diz respeito às pesquisas com dispositivos de micro-ondas que utilizam geometrias fractais. Devido às características próprias e a forma geométrica dos elementos pré-fractais de Peano, a possibilidade de reconfiguração destas estruturas também é investigada e discutida. Esta Tese aborda ainda, a construção de filtros seletivos eficientes com novas configurações de patches pré-fractais do tipo terágonos, propostos para controle de cobertura WLAN em ambientes indoor, rejeitando os sinais nas faixas de 2,4~2,5 GHz (IEEE 802.11b) e 5,0~6,0 GHz (IEEE 802.11a). As FSSs são analisadas inicialmente por meio de simulações executadas pelos programas comerciais Ansoft DesignerTM e HFSSTM. A metodologia de projeto é validada através da caracterização experimental dos protótipos construídos utilizando, alternativamente, diferentes setups de medição, com antenas corneta comerciais e monopolos de microfita de fabricação própria para medições de baixo custo.

     
6
  • DANIEL GOUVEIA COSTA
  • Otimizações da Transmissão de Imagens em Redes de Sensores Visuais Sem Fio Explorando a Relevância de Monitoramento dos Nós Fontes e Codificação DWT

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ANTÔNIO ALFREDO FERREIRA LOUREIRO
  • AUGUSTO JOSE VENANCIO NETO
  • CELSO ALBERTO SAIBEL SANTOS
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • Data: Apr 29, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • O desenvolvimento de redes de sensores sem fio para funções de controle e monitoramento tem criado um pulsante cenário de investigação, abrangendo desde aspectos da comunicação em rede até questões como eficiência energética. Quando sensores são equipados com câmeras para funções de monitoramento visual, um novo escopo de
    desafios é lançado, uma vez que há uma mudança significativa nos requisitos de monitoramento e transmissão. Em particular, sensores visuais coletam dados seguindo um modelo direcional de monitoramento, alterando conceitos já estabelecidos de vizinhança e redundância, porém tornando possível a diferenciação de sensores pelas suas relevâncias de monitoramento para a aplicação. Nesse contexto, propomos que a relevância de monitoramento dos sensores fontes sejam exploradas em conjunto com a codificação de imagens por transformada DWT, unindo assim dois diferentes escopos de relevância para a criação de novos parâmetros de QoS. Essa abordagem inovadora permite uma nova gama de otimizações da operação da rede, possibilitando aumento de desempenho com pequenas perdas na qualidade global de monitoramento. Além da definição de um novo conceito de relevância e a proposição de mecanismos para suportar sua utilização prática, cinco diferentes otimizações da transmissão de imagens em redes de sensores visuais sem fio são propostas visando economia de energia, transmissão com baixo atraso e recuperação de erros. Em conjunto, as estratégias de diferenciação e as otimizações relacionadas abrem uma importante vertente de pesquisa, onde os requisitos de monitoramento das aplicações são utilizados para guiar uma operação mais eficiente da rede.



7
  • FRANCISCO JOSÉ TARGINO VIDAL
  • Calibração de Receptores Cinco-Portas Baseada em Separação Cega de Fontes

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • EDMAR CANDEIA GURJÃO
  • HELIO MAGALHAES DE OLIVEIRA
  • Data: May 24, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Estudos recentes apontam que o aumento nas aplicações de rádio frequência (RF) vem acompanhado por grandes desafios tanto no uso eficiente do espectro eletromagnético quanto no projeto de novas arquiteturas para receptores multi-padrão, ou rádio definidos por software (RDS). O principal desafio da arquitetura física de um RDS é a implementação de um receptor banda-larga com características de baixo custo, baixo consumo, maior grau de integração e flexibilidade.

    A arquitetura homodina, baseada na tecnologia cinco-portas, surge como uma alternativa para aplicações em rádio definidos por software. No entanto, a regeneração das componentes em fase e quadratura, no receptor cinco-portas, comumente denominada de calibração, constitui um dos maiores desafios na aplicação dessa tecnologia.

    Os métodos de calibração, propostos na literatura, normalmente baseiam-se no conhecimento do modelo matemático do circuito, em que o mesmo é calibrado previamente (off-line), para um tipo de sinal com características específicas ou em tempo real, com base no conhecimento da sequência de aprendizagem e do tipo de modulação. Nesse trabalho, é apresentado uma proposta de regeneração “cega” dessas componentes, para um receptor homodino cinco-portas, utilizando a abordagem denominada Separação Cega de Fontes (análise de componentes independentes - ICA), que explora as características estatísticas dos três sinais de saída do receptor cinco-portas. A validação dessa abordagem é realizada por meio de simulação e de resultados experimentais obtidos para o receptor cinco portas implementado em tecnologia de microfita.

8
  • JOEMIA LEILANE GOMES DE MEDEIROS MARTINS
  • ANÁLISE DE ANTENAS UTILIZANDO SUBSTRATO  CERÂMICO, ZPT, PRODUZIDO POR SÍNTESE AUTO
    PROPAGANTE PARA APLICAÇÕES EM SISTEMAS  DE MICRO-ONDAS

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • LAERCIO MARTINS DE MENDONCA
  • ADAILDO GOMES D ASSUNCAO
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • ALFREDO GOMES NETO
  • MARCOS TAVARES DE MELO
  • Data: Jun 7, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Nos últimos anos, diversos esforços foram feitos visando à utilização de novos materiais na construção de dispositivos usados na faixa de freqüência de microondas, incluindo as antenas de microfita. Dentre estes, destacam-se os materiais cerâmicos de alta permissividade elétrica. Neste trabalho, foram projetados e construídos substratos dielétricos cerâmicos de alta permissividade elétrica usando o dióxido de titânio ( 2 TiO ). Estes substratos foram utilizados na construção de antenas de microfita para operar na faixa de comunicações sem fio. O uso deste tipo de material cerâmico proporciona uma redução no tamanho das antenas, uma grande eficiência de radiação e boa integração com outros circuitos de micro-ondas.

9
  • LEONARDO AUGUSTO CASILLO
  • Metodologia para adaptação de microarquiteturas microprogramadas soft-core à uma ISA padrão: Estudo do Impacto sobre a complexidade de hardware para o padrão MIPS

  • Advisor : IVAN SARAIVA SILVA
  • COMMITTEE MEMBERS :
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • DANNIEL CAVALCANTE LOPES
  • IVAN SARAIVA SILVA
  • KARLA DARLENE NEPOMUCENO RAMOS
  • MONICA MAGALHAES PEREIRA
  • Data: Jul 11, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • No meio acadêmico, é comum a criação de processadores denominados didáticos ou acadêmicos, voltados para práticas de disciplinas de hardware na área de Computação e que podem ser utilizados como plataformas em disciplinas de softwares, sistemas operacionais e compiladores. Muitas vezes, tais processadores são descritossem uma ISA padrão, o que exige a criação de compiladores e outros softwares básicos para prover a interface hardware/software e dificulta sua integração com outros processadores e demais dispositivos. A Computação Reconfigurável, ao proporcionar a criação ou modificação de qualquer processador descrito em uma linguagem do tipo HDL, permite que o caminho de dados que representa a parte operativa de um processador, bem como a máquina de estados que implementa a unidade de controle do mesmo, possam ser reescritos e alterados conforme surgem novas necessidades.

    Em particular, os processadores RISP possibilitam a alteração das instruções da máquina, permitindo inserir ou modificar instruções, podendo até mesmo se adaptar a uma nova arquitetura. Este trabalho, abordando como objeto de estudo processadores didáticos soft-core descritos em VHDL, a partir de uma metodologia proposta e sua aplicação em dois processadores com diferentes níveis de complexidade, mostra que é possível adaptar processadores para uma ISA padrão sem provocar aumento no nível de complexidade do hardware, ou seja, sem o acréscimo significativo da área em chip, ao mesmo tempo em que o seu nível de desempenho na execução de aplicações permanece inalterado ou é aprimorado. As implementações também permitem afirmar que além de ser possível substituir a arquitetura de um processador sem alterar sua organização, um processador RISP pode alternar entre diferentes conjuntos de instrução, o que pode ser expandido para alternância entre diferentes ISAs, permitindo a um mesmo processador se tornar uma arquitetura híbrida adaptativa, passível de ser utilizada em sistemas embarcados e ambientes multiprocessados heterogêneos.

10
  • HUGO MICHEL CAMARA DE AZEVEDO MAIA
  • Arranjo de Antenas de Microfita com Substrato Anisotrópico com Patch Supercondutor e Aplicações em Nanotecnologia


  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • VALENTIN OBAC RODA
  • ALFREDO GOMES NETO
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Data: Jul 30, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como objetivo principal a aplicação em bandas de alta frequência em estruturas de microfita com substrato anisotrópico e análise de antenas de microfita, com patch circular e retangular supercondutor HTS, com frequência de ressonância em Giga e Terahertz. São desenvolvidos arranjos de antenas de microfita de fase linear e planar , acoplados, com patch supercondutor. É apresentado um estudo das principais teorias que explicam a supercondutividade. As teorias BCS, Equações de London e modelo dos Dois Fluidos são as teorias que dão suporte a aplicação dos supercondutores nas antenas de microfita. Os arranjos de fase são analisados em configurações lineares e planares de suas antenas. Foram obtidos os fatores de arranjos para tais configurações, e os critérios da fase e do espaçamento entre os elementos que compõe o arranjo, ao qual foram examinados com o objetivo de obter um lóbulo principal com alta diretividade e alto ganho. A antena utilizada tem como patch retangular o material supercondutor YBCO, Sn5InCa2Ba4Cu10Oy  foi analisada através do método da Linha de Transmissão Transversa (LTT), aplicado no domínio da transformada de Fourier (FTD). O LTT é um método de onda completa, que tem como regra a obtenção dos campos eletromagnéticos em termos das componentes transversais à estrutura. A inclusão do patch supercondutor é feita utilizando-se a condição de contorno complexa resistiva. São obtidos resultados da freqüência de ressonância em função dos parâmetros da antena; diagramas de radiação do Plano-E e Plano-H para os arranjos de fase de antenas nas configurações lineares e planares para diferentes valores da fase e espaçamento entre os elementos.

11
  • RAFAEL BESERRA GOMES
  • Seleção de features guiada por atenção visual em imagens com fóvea

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • BRUNO MOTTA DE CARVALHO
  • LUIZ CHAIMOWICZ
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • ROBERTO MARCONDES CESAR JUNIOR
  • Data: Aug 2, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • A atenção visual é uma importante tarefa em robótica autônoma, mas devido à sua complexidade, o tempo de processamento necessário é significativo. Propõe-se uma arquitetura para seleção de features usando imagens foveadas que é guiada por tarefas envolvendo atenção visual e que reduz o tempo de processamento para realizar tais tarefas. O sistema proposto pode ser aplicado para atenção bottom-up ou top-down. O modelo de foveamento determina quais escalas devem ser utilizadas no algoritmo de extração de features. O sistema é capaz de descartar features que não são essenciais para a realização da tarefa e, dessa forma, reduz o tempo de processamento. Se a fóvea é corretamente posicionada, então é possível reduzir o tempo de processamento sem comprometer o desempenho da tarefa. A distância da fóvea para o objeto também é analisada. Caso o sistema visual perca o tracking na atenção top-down, estratégias básicas de reposicionamento da fóvea podem ser aplicadas. Experimentos demonstram que é possível reduzir em até 60% o tempo de processamento com essa abordagem. Para validar esse método, testes são realizados com o algoritmo de extração de features SURF, um dos algoritmos mais eficientes na extração de features. Com essa arquitetura, é possível cumprir requisitos de um sistema de visão em tempo-real, principalmente em aplicações de robótica autônoma.

12
  • FERNANDO CESAR DE MIRANDA
  • Métodos Estatísticos Recursivos Aplicados ao Problema de Estimação de Vazão de Gás em Plantas de "Plunger-lift"

  • Advisor : FRANCISCO DAS CHAGAS MOTA
  • COMMITTEE MEMBERS :
  • FRANCISCO DAS CHAGAS MOTA
  • ILONEIDE CARLOS DE OLIVEIRA RAMOS
  • PABLO JAVIER ALSINA
  • RICARDO TAVARES
  • TANIA LUNA LAURA
  • Data: Aug 23, 2013


  • Show Abstract
  • Neste trabalho aprsentamos o desenvolvimento de algoritmos recursivos baseados em técnicas estatísticas aplicados ao problema de estimação de vazão de gás em tempo real para poços de petróleo produzido pelo método de "plunger-lift". Inicialmente descrevemos as características do metodo de "plunger-lift" e as necessidades de um instrumento de medida confiável. A seguir, usamos conceito de função de transferência para sistemas lineares invariantes no tempo sob a ótica de séries temporais, com o objetivo de dar um embasamento teórico ao modelo proposto. Os dados utilizados para validação do modelo foram obtidos de uma planta piloto desenvolvida no Laboratório de Elevação de Petróleo da UFRN.

13
  • HUMBERTO DIONISIO DE ANDRADE
  • Desenvolvimento de um Ressoador Retangular de Fenda com Múltiplas Camadas de Substrato e com Utilização de Material PBG para Sistema de Comunicação Sem Fio

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • VALENTIN OBAC RODA
  • AUGUSTO CARLOS PAVAO
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Data: Sep 2, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • No mundo globalizado moderno, as telecomunicações assumiram papel fundamental dentro das sociedades, provocando um grande aumento de demanda pela a tecnologia de comunicação sem fio, que vem acontecendo nos últimos anos tem aumentado bastante o número de aplicações que utilizam esta tecnologia. Em decorrência dessa demanda, novos materiais são desenvolvidos no sentido de possibilitar novos mecanismos de controle e propagação de ondas eletromagnéticas. A pesquisa para o desenvolvimento de novas tecnologias para comunicação sem fios apresenta caráter multidisciplinar que abrange desde o estudo de novas geometrias para antenas passivas, ativas até o de desenvolvimento de materiais para dispositivos que melhorem se desempenho naquela faixa de freqüência de operação.

    Recentemente as antenas planares tem despertado interesses devido as suas características e vantagens que oferecem quando comparadas com os demais tipos de antenas.

    Na área de comunicações móveis a necessidade de antenas desse tipo, tem se tornado cada vez mais utilizada devido ao intenso desenvolvimento, que necessita de antenas que operem em multifrequência e em banda larga. As antenas de microfita apresentam largura de banda estreita devido às perdas no dielétrico geradas pela irradiação. Outra limitação é a degradação do diagrama de irradiação devido à geração de ondas de superfície no substrato. Algumas técnicas estão sendo desenvolvidas para minimizar esta limitação de banda, como é o caso do estudo de materiais do tipo PBG – Photonic Band Gap, para compor o material dielétrico.

    Este trabalho tem como objetivo principal o desenvolvimento de projeto de um ressoador de fenda com múltiplas camadas e com utilização de substrato do tipo PBG, onde fora realizada a otimização a partir da analise numérica e em seguida, projetado o dispositivo proposto inicialmente para a faixa do espectro eletromagnético compreendida entre 3-9 GHz, que inclui basicamente a banda S até X. Foi utilizado como material dielétrico o RT/Duroid 5870 e RT/Duroid 6010.2LM onde ambos são laminados cerâmicos - PTFE com constantes dielétricas de 2.33 e 10.2, respectivamente. Através de uma investigação experimental foi realizado uma análise dos resultados simulados versus medidos observando o comportamento das características de radiação a partir da variação da altura das multicamadas de subtrato dielétrico.

    Foi utilizado também o método LTT às estruturas ressoadoras retangulares de fenda com múltiplas, para a obtenção da freqüência de ressonância bem como toda a teoria que envolva os parâmetros eletromagnéticos da estrutura em estudo.

    As análises desenvolvidas neste trabalho foram realizadas com utilização do método LTT – Linha de Transmissão Transversa, no domínio da Transformada de Fourier que utiliza uma componente de propagação na direção y (transversa à direção real de propagação z), tratando assim as equações gerais dos campos elétricos e magnéticos em função de e . A teoria PBG será aplicada para a obtenção da permissividade relativa para as polarizações s e p dos substratos compostos de material fotônico.

    Os resultados são obtidos com o software comercial Ansoft HFSS, usado para a análise precisa do comportamento eletromagnético do dispositivo planar em estudo, por meio do Método dos Elementos Finitos (FEM).

    Resultados numérico-computacionais são apresentados em forma de gráfico em duas e três dimensões, para aos parâmetros de perda de retorno, frequência de radiação, e diagrama de radiação para o dispositivo em estudo, e que tem como substratos, materiais fotônicos e que fora simulado em uma ferramenta computacional apropriada. No que diz respeito ao projeto do dispositivo planar em estudo são apresentados os resultados simulados e medidos que apresentam boa concordância com as medições efetuadas. Estes resultados consistem principalmente na identificação dos modos de ressonância e na determinação das características do dispositivo projetado, como freqüência de ressonância, perda de retorno e diagrama de radiação.

14
  • LUIZ AMORIM CARLOS
  • Algoritmos Genéticos: Uso de Lógica Nebulosa e Análise de Convergência por Cadeia de Markov

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ADRIAO DUARTE DORIA NETO
  • DANIEL ALOISE
  • DARIO JOSE ALOISE
  • LUIZ SATORU OCHI
  • Data: Nov 5, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Neste trabalho, a cadeia de Markov será a ferramenta usada tanto na modelagem quanto na análise de convergência do algoritmo genético, tanto na sua versão padrão quanto nas demais. A escolha deste algoritmo deve-se ao fato do mesmo ter se tornado, nos últimos trinta anos, uma das ferramentas mais usadas para achar uma solução do problema de otimização. Esta escolha deve-se à sua comprovada eficácia na busca de uma solução de boa qualidade para o problema, considerando que o conhecimento de uma solução de boa qualidade torna-se aceitável tendo em vista que pode não existir um outro algorimo capaz de obter a solução ótima, para muitos desses problemas. Entretanto, esse algoritmo pode ser definido, levando em conta que o mesmo é dependente não apenas da forma como o problema é representado mas também como são definidos alguns dos operadores, desde sua versão padrão, quando os parâmetros são mantidos fixos, até suas versões com parâmetros variáveis. Por isso, para se alcançar um bom desempenho com o aludido algoritmo é necessário que o mesmo tenha um adequado critério na escolha de seus parâmetros, principalmente a taxa de mutação e taxa de cruzamento ou, até mesmo, o tamanho da populaçao. É importante lembrar que naquelas implementações em que parâmetros são mantidos fixos durante toda a execução, a modelagem do algoritmo por cadeia de Markov resulta numa cadeia homogênea e quando permite a variação de parâmetros ao longo da execução, a cadeia de Markov que o modela passa a ser do tipo não-homogênea. Portanto, na tentativa de melhorar o desempenho do algoritmo, alguns trabalhos têm procurado realizar o ajuste dos parâmetros através de estratégias que captem características intrínsecas ao problema. Essas características são extraidas do estado presente de execução, com o fim de identificar e preservar algum padrão relacionado a uma solução de boa qualidade e, ao mesmo tempo, descartando aquele padrão de baixa qualidade. As estratégias de extração das características tanto podem usar técnicas precisas quanto técnicas nebulosas, sendo neste último caso feita através de um controlador nebuloso. Com o fim de avaliar o desempenho de um algoritmo não-homogêneo, apresenta-se testes onde se compara o algoritmo genético padrão com o algoritmo genético nebuloso, sendo a taxa de mutação ajustada por um controlador nebuloso. Para isso, escolhe-se problemas de otimização cujo número de soluções varia exponencialmente com o número de variáveis. 

15
  • ANDRE PEDRO FERNANDES NETO
  • Modelagem de Equações Estruturais na Análise de Dados em Serviços de Comunicações Móveis.

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • JOSE PATROCINIO DA SILVA
  • PAULO CESAR FORMIGA RAMOS
  • AUGUSTO CARLOS PAVAO
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • Data: Dec 13, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Transformações ocorridas no setor de telecomunicações nas últimas décadas, aliadas

    à competição motivada pelas políticas de concessões e privatizações, fomentaram, de

    forma irrefutável, o mercado mundial, causando o surgimento de uma nova realidade.

    Os reflexos, no Brasil, tornaram-se evidentes devido ao aparecimento de taxas de

    crescimento acentuadas, chegando em 2012 a apresentar uma receita operacional

    líquida de 128 bilhões de reais, colocando o país entre os cinco maiores países em

    relação a comunicações móveis no mundo. Neste contexto econômico, uma questão

    de crescente importância para a saúde financeira das empresas é a sua capacidade

    de reter seus clientes e transformá-los em consumidores leais. O aparecimento da

    infidelidade dos clientes nas operadoras vem gerando valores de taxas de desligamentos

    mensais em média na ordem de dois a quatro por cento, representando para a gestão

    empresarial um dos seus maiores desafios, vez que a captação de um novo cliente

    significa um dispêndio cinco vezes maior que sua retenção. Com este propósito,

    modelos têm sido desenvolvidos, por meio da modelagem de equações estruturais,

    para identificar as relações entre os diversos determinantes da lealdade dos clientes

    no contexto dos serviços. A contribuição original desta tese é o desenvolvimento de

    um modelo para a lealdade a partir da identificação de relações entre determinantes da

    satisfação (variáveis latentes) e da inclusão de atributos que determinam as percepções

    da qualidade de serviço para o setor de comunicações móveis, entre os quais: qualidade,

    satisfação, valor, confiança, expectativa e lealdade. A pesquisa de caráter quantitativo

    foi realizada com os clientes das operadoras por meio da técnica de amostragem

    aleatória simples, por meio de questionários estruturados. Como resultado o modelo

    proposto e as avaliações estatísticas devem possibilitar as operadoras concluírem que

    a lealdade dos clientes é diretamente influenciada pela qualidade técnica e operacional

    dos serviços oferecidos, bem como apresentar um índice de satisfação de comunicações

    móveis para o segmento.

16
  • CARLOS EDUARDO SILVEIRA DIAS
  • Uma Arquitetura para Formação de Inter-Redes de Compartilhamento de Ativos Digitais

  • Advisor : GUIDO LEMOS DE SOUZA FILHO
  • COMMITTEE MEMBERS :
  • ALISSON VASCONCELOS DE BRITO
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • DENIO MARIZ TIMOTEO DE SOUSA
  • GUIDO LEMOS DE SOUZA FILHO
  • LUIZ EDUARDO CUNHA LEITE
  • Data: Dec 18, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Atualmente a produção de conteúdo audiovisual está cada vez mais baseada em sistemas totalmente digitais, onde o conteúdo torna-se um ativo digital de valor para as organizações. Ao mesmo tempo, as organizações trabalham em um ambiente de rede, que impõe desafios para a formação de parcerias para compartilhamento e distribuição dos ativos digitas entre estas organizações, uma vez que cada organização tem um modelo de negócios próprio onde é definido como negociar, compartilhar e distribuir seus ativos digitais, envolvendo contratos de uso e políticas de acesso ao conteúdo. Neste sentido, este trabalho propõe a definição de uma arquitetura para formação uma interrede de compartilhamento de ativos digitais. Na arquitetura proposta, cada organização é vista como uma rede, possuindo suas próprias políticas de acesso aos seus ativos digitais e contratos que regulam a interação os participantes da interrede. Para a formação da interrede, as redes são conectadas através dos Pontos de Troca de Conteúdo (PTC). Cada rede define que ativos digitais publicar, quais os contratos válidos para interconexão entre participantes e quais as políticas de acessos aos ativos digitais disponibilizados. Se algum participante da interrede deseja um ativo digital que não está disponível ou tem uma política limitada de acesso, é possível estabelecer novos contratos através uma negociação entre os participantes para o acesso a este novo ativo digital. Por fim, testes e simulações foram conduzidos para validar aspectos da arquitetura proposta em um ambiente em rede distribuído, como a negociação contratual entre os participantes,respeito às políticas de acesso definidas aos conteúdos, formação da interrede e a escalabilidade da arquitetura.

17
  • JOAO PAULO DE SOUZA MEDEIROS
  • A Influencia da Observabilidade e da Visualização Radial no Projeto de  Sistemas de Monitoramento de Redes de Computadores

  • Advisor : PAULO SERGIO DA MOTTA PIRES
  • COMMITTEE MEMBERS :
  • PAULO SERGIO DA MOTTA PIRES
  • ALLAN DE MEDEIROS MARTINS
  • FRANCISCO DAS CHAGAS MOTA
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ANTÔNIO ALFREDO FERREIRA LOUREIRO
  • ROMMEL WLADIMIR DE LIMA
  • Data: Dec 20, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho apresenta um levantamento dos problemas associados à influência da observabilidade e da visualização radial no projeto de sistemas de monitoramento para redes de grande magnitude e complexidade. Além disso, se propõe a apresentar soluções para parte desses problemas.

    Através da utilização da Teoria de Redes Complexas, são abordadas duas questões:

    (i) a localização e a quantidade de nós necessários para garantir uma aquisição de dados capaz de representar o estado da rede de forma efetiva e

    (ii) a elaboração de um modelo de visualização das informações da rede capaz de ampliar a capacidade de inferência e de entendimento de suas propriedades.

    A tese estabelece limites teóricos a estas questões e apresenta um estudo sobre a complexidade do monitoramento eficaz, eficiente e escalável de redes.

18
  • JOSE ALBERTO DIAZ AMADO
  • Otimização do sistema de supervisão e controle de uma planta de tratamentos de residuos utilizando plasma térmico

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ALBERTO SOTO LOCK
  • JEAN PAUL DUBUT
  • Data: Dec 20, 2013
  • View Dissertation/Thesis  

  • Show Abstract
  • Um dos grandes e crescentes problemas enfrentado pela sociedade moderna é a alta produção de resíduos e os efeitos correlatos que produzem, tais como a degradação do meio ambiente e a poluição dos diversos ecossistemas, com reflexos diretos na qualidade de vida das populações. As tecnologias de tratamento térmico têm sido largamente empregadas no tratamento destes resíduos e o plasma térmico vem ganhando importância no processamento de eliminação de resíduos. O objetivo neste trabalho, está focado no desenvolvimento de um sistema otimizado de supervisão e controle aplicado a uma planta de processamento de resíduos e efluentes petroquímicos utilizando plasma térmico. O sistema é basicamente composto por uma tocha indutiva plasmática, reatores, sistema de lavagem e exaustão de gases e uma fonte de alimentação utilizada na geração de plasma. O desenvolvimento de um ambiente de simulação da planta de inertização de resíduos, permitiu a interação entre a eletrônica, mecânica, monitoramento de dados e controle dos diferentes subsistemas envolvidos, sendo de vital importância na observação e identificação do processo de uma maneira mais clara e viável, dando assim uma cobertura melhorada no desenvolvimento da planta real. Para poder alcançar o estado de ignição de plasma, foi utilizado uma tocha de acoplamento indutivo, analisando o equilíbrio do campo magnético por meio da corrente elétrica, o gás argônio e um sistema de refrigeração aplicada na tocha. O controle deste processo para manter a temperatura desejada, foi por médio da lógica fuzzy em cascata, mostrando resultados satisfatórios em termos de tempo de resposta e viabilidade na implementação.
    Outro desafio encontrado neste trabalho, foi a integração dos subsistemas da planta, já que forem desenvolvidos separadamente e em épocas diferentes.

2012
Dissertations
1
  • ELLON PAIVA MENDES
  • Identificação em Tempo Real de Modelo Dinâmico de Robô Móvel com Acionamento Diferencial e Zona Morta

  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ANDRE GUSTAVO SCOLARI CONCEICAO
  • CARLOS EDUARDO TRABUCO DOREA
  • PABLO JAVIER ALSINA
  • Data: Jan 27, 2012


  • Show Abstract
  • Vários robôs móveis apresentam comportamentos não-lineares, principalmente ocasionados por fenômenos de atrito entre as partes mecânicas do robô ou entre o robô e o solo. Modelagens puramente lineares apresentam-se eficientes em alguns casos, mas é preciso levar em consideração as não-linearidades do robô quando se deseja movimentos ou posicionamentos precisos. Este trabalho propõe um procedimento de identificação paramétrica do modelo de um robô móvel com acionamento diferencial, no qual são consideradas as não-linearidades do tipo zona-morta presente nos atuadores do robô. A proposta baseia-se no modelo de Hammerstein para dividir o sistema em blocos lineares e não-lineares. O princípio da separação do termo chave é utilizado para demonstrar a relação entre as entradas e saídas do sistema com os parâmetros tanto da parcela linear quando da não-linear. Os parâmetros de ambas as parcelas são identificados simultaneamente, através de um algoritmo de mínimos quadrados recursivo.

2
  • VITOR FERNANDES DE BARROS
  • Estudo do Efeito de Substratos Metamateriais em Parâmetros de Antenas de Microfita

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • SANDRO GONCALVES DA SILVA
  • Data: Feb 3, 2012


  • Show Abstract
  • As antenas de microfita podem ser encontradas em diversos campos de pesquis a, devido a suas inúmeras vantagens. A descoberta, mais recente, de uma nova classe de   materiais, chamados metamateriais - normalmente compostos por elementos metálicos imersos em um meio dielétrico, têm atraído a atenção da comunidade científica, graças às suas propriedades eletromagnéticas e, principalmente, pela capacidade de utilização em estruturas planares, tais como a microfita, sem interferir em sua geometria tradicional. O objetivo desse trabalho é analisar os efeitos do uso de substratos metamateriais uni e bidimensionais em antenas de microfita, com diferentes configurações de anéis de ressonância - SRR - na camada dielétrica. A geometria fractal é aplicada a esses anéis, na busca de se obter um comportamento multibanda e de se reduzir a frequência de ressonância das antenas. Os resultados são, então, obtidos com o software comercial Ansoft HFSS, usado para a análise precisa do comportamento eletromagnético das antenas, por meio do Método dos Elementos Finitos (FEM). Para tanto, nessa dissertação, é previamente realizado um breve estudo bibliográfico sobre a geometria fractal e seu processo gerador. Este trabalho apresenta também uma análise sobre as antenas de microfita, com ênfase à abordagem de diferentes tipos de substratos, evidenciando seu comportamento anisotrópico elétrico e magnético. É realizada, ainda, uma abordagem superficial sobre os metamateriais e suas propriedades singulares. Para a validação dos resultados, vários modelos de antena de microfita foram construídos e comparativamente medidos, em relação aos simulados, por meio de um analisador de rede vetorial.

3
  • ANTONIO JOSE FERREIRA VIEIRA
  • Utilização de Substratos Heterogêneos e Planos de Terra Inclinados no Desenvolvimento de Antenas e Filtros de Microfita Sintonizáveis

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • SANDRO GONCALVES DA SILVA
  • MARCOS TAVARES DE MELO
  • SILVIO ERNESTO BARBIN
  • Data: Feb 10, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como objetivo principal apresentar filtros e antenas de microfita sintonizáveis, que permitam alterações da frequência de ressonância e da largura de banda, para aplicações em sistemas de comunicação sem fio. Assim, em sistemas que apresentem níveis elevados de ruídos, alterações da frequência de operação e de largura de banda podem proporcionar maior confiabilidade ao tráfego das informações e melhoria na relação sinal ruído do sistema.

    Para que estes dispositivos se tornassem sintonizáveis foi proposta uma técnica que consiste em introduzir uma inclinação ao plano de terra e variá-la conforme a necessidade de adaptação dos dispositivos. A teoria de circuitos e a teoria da linha de transmissão foram usadas no projeto desses filtros e antenas de microfita, em combinação com a técnica do plano de terra inclinado, foi inserida nas estruturas destes dispositivos, que foram simulados no software comercial Ansoft-HFSS para avaliação da predição teórica.

    Após as simulações foram construídos vários protótipos, que foram medidos em um analisador de rede vetorial. Os resultados simulados e medidos foram então comparados e apresentaram uma boa concordância. Estes resultados mostraram um aumento de até 120% na largura de banda dos filtros e uma variação de até 31% na frequência de ressonância das antenas estudadas. Assim, através da análise das respostas dos dispositivos de microfita estudados pode-se observar que a aplicação da técnica do plano de terra inclinado proporciona um aumento considerável na largura de banda dos filtros e uma variação percentual significativa  na frequência de ressonância das antenas. Portanto, esta técnica mostrou-se adequada para o ajuste das respostas de dispositivos de microfita com aplicação em filtragem e radiação eletromagnética.

4
  • HUGO TACITO AZEVEDO DE SENA
  • TrendTV: Uma Arquitetura para Mudança Automática de Canais de TV Baseada em Redes Sociais Virtuais com Graus de Amizade e Suporte a Múltiplos Dispositivos no Cenário da TV Digital Brasileira

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ EDUARDO CUNHA LEITE
  • JOSE CARLOS ARONCHI DE SOUZA
  • SERGIO QUEIROZ DE MEDEIROS
  • Data: Feb 13, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Devido a grande quantidade de conteúdo televisivo, que surgiu junto a TV Digital, os telespectadores estão diante de um novo desafio, saber como procurar conteúdo interes- sante de maneira intuitiva e eficiente. Os guias eletrônicos de programação personalizado (pEPG) surgem como uma resposta para esse complexo desafio. Propomos a TrendTV, uma arquitetura em camadas que permite a formação de redes sociais entre telespecta- dores de programas de TV Digital Interativa baseada em microblog de conteúdo on-line. Associado a um pEPG, esta rede social permite que um telespectador possa realizar fil- tragens de conteúdo sobre um determinado assunto a partir das indicações feitas por ou- tros telespectadores de sua rede. Permitindo que o telespectador possa criar sua própria indicação para um determinado conteúdo no momento em que ele é exibido, ou ainda analisar a importância de um determinado programa on-line, baseado nessas indicações. Isto permite que qualquer usuário possa realizar filtros no conteúdo, além de gerar e tro- car informações com os outros usuários de modo flexível e transparente, utilizando vários dispositivos diferentes(TVs,Smartfones, Tablets ou PCs). Além disso, essa arquitetura define um mecanismo para realizar a mudança automática de canais baseado no melhor programa que está passando no momento, sugerindo novos componentes a serem agre- gados ao middleware do Sistema Brasileiro de TV Digital (Ginga). Como resultado é construída uma base de dados dinâmica e que contém a classificação de vários programas de TV, bem como uma aplicação que permite mudar automaticamente para o melhor canal do momento.

5
  • RICARDO ALEXANDRE DA ROCHA DIAS
  • MultiArt: Uma API para Integração de Serviços Multimidia e Robótica com Espetáculos de Arte Telemática

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ EDUARDO CUNHA LEITE
  • SERGIO QUEIROZ DE MEDEIROS
  • Data: Feb 13, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho descreve o MultiArt, uma API para o provimento de serviços para apresentações e divulgação de cultura. O MultiArt integra componentes que incluem servidores de ambientes virtuais em 3D, servidores de vídeo, controle robótico, captura de movimentos através de sensores com o objetivo de provimento de serviços a serem utilizados na configuração de espetáculos de arte telemática. Apresentamos sua arquitetura e implementação de casos de uso utilizando o MultiArt. Nosso estudo de caso prevê componentes que capturam movimento de dançarinos, dançando ao som de músicas criadas colaborativamente, seus movimentos são repassados para um ambiente virtual em três dimensões, dando vida a avatares, que por sua vez se conectam a dispositivos robóticos e enviam fluxos de vídeo para um programa de TV digital interativa. 

6
  • ANDRE FREITAS BARBOSA
  • Um sistema inteligente de classificação de sinais para Interface Cérebro-Computador

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • ANTONIO PEREIRA JUNIOR
  • HELIANA BEZERRA SOARES
  • ADRIANO DE ANDRADE BRESOLIN
  • Data: Feb 24, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Uma interface cérebro-computador (ICC) é um sistema computacional capaz de interpretar informação neurofisiológica e, a partir disto, controlar um dispositivo, seja ele um computador, uma cadeira de rodas, ou até mesmo um braço mecânico. Dessa forma é criado um canal de comunicação independente das vias padrão de nervos e músculos. O principal objetivo desta tecnologia é reparar ou ampliar funções motoras ou cognitivas.

    Este trabalho propõe um estudo exploratório  de uma ICC off-line baseada em EEG, utilizando de tarefas mentais para a geração de padrões diferenciáveis entre si. Diferentes combinações de técnicas de pré-processamento, extração de característica e classificadores serão testadas para identificar uma possível estrutura para uma ICC on-line.

7
  • LUIZ PAULO DE SOUZA MEDEIROS
  • Uma ferramenta para a Análise Multiresolução de Dados não regularmente amostrados

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • MARCELO AUGUSTO COSTA FERNANDES
  • JOSE DIAS DO NASCIMENTO JUNIOR
  • ADRIANO DE ANDRADE BRESOLIN
  • Data: Feb 24, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • As missões espaciais, assim como as demais áreas da pesquisa científica, vêm se desenvolvendo e utilizando cada vez mais recursos tecnológicos para a execução de suas observações. A missão espacial CoRoT é um exemplo dessa evolução, com o satélite em funcionamento a aproximadamente 3 anos, já foram coletadas milhares de observações, resultando num massa de
    dados a ser analisada de aproximadamente 1 TB.
                 Devido a essa grande quantidade de informações a serem processadas, faz-se necessário o uso de ferramentas que auxiliem os pesquisadores na análise visual dos dados em questão, bem como o uso de mecanismos inteligentes que sejam capazes de identificar casos que mereçam maior atenção dos pesquisadores.
                 Esse trabalho propõe o desenvolvimento de ferramentas que possam auxiliar essas pesquisas. Tais ferramentas serão desenvolvidas utilizando tecnologias que estão sendo constantemente utilizadas em suas áreas, as transformada wavelet para o processamento dos sinais, e as redes neurais artificias para a identificação e classificação das informações.

8
  • RAPHAEL DANTAS CIRIACO
  • Sistema Embarcado à Microcontrolador para Coleta, Rastreamento e
    Transmissão de dados

  • Advisor : JOSE ALBERTO NICOLAU DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • DAVID SIMONETTI BARBALHO
  • JEAN PAUL DUBUT
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • Data: Mar 30, 2012


  • Show Abstract
  • Propõe o desenvolvimento de um Sistema Embarcado à Microcontrolador para
    Coleta, Rastreamento e Transmissão de dados, o SEMCRTD, de baixo custo
    capaz de obter e transmitir via satélite vários tipos de medições de
    acordo com sua aplicação, desde medições climatológicas até rastreamento
    de animais e de veículos/embarcações, graças a um módulo GPS. O sistema
    foi desenvolvido utilizando um microcontrolador com software embarcado
    em linguagem C, responsável pelo processamento dos dados, compactação da
    mensagem de GPS sem comprometimento de sua precisão e transmissão da
    mensagem aos satélites do Sistema Brasileiro de Coleta de Dados Ambientais
    e do sistema Argos, responsáveis pela retransmissão dos dados aos seus
    usuários.

9
  • BRENO MEIRA MOURA DE AMORIM
  • Controlador Adaptativo Backstepping a Estrutura Variável com Observadores
    de Estado

     

    Projeto de Controlador Adaptativo Backstepping com Estrutura Variável com a Utilização de Observadores de Estado
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • DARLAN ALEXANDRIA FERNANDES
  • JOSENALDE BARBOSA DE OLIVEIRA
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • Data: Apr 12, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Os controladores adaptativos backstepping mesmo com várias vantagens de desempenho, ainda possuem algoritmos muito complexos, principalmente quando se trata da obtenção das variáveis de estado do sistema, pois o uso de filtros no sinal de saída da planta não é algo trivial. Na intenção de
    tornar o projeto do controlador mais intuitivo, pode-se utilizar um observador adaptativo em alternativa aos comumente utilizados filtros K para estimação das variáveis de estado. Além disso, a lei de controle torna-se bem mais simples, pois a substituição diminui a dependência dos parâmetros desconhecidos da planta na fase de projeto, já que as variáveis de estado são consideradas conhecidas. E ainda, leis chaveadas podem ser utilizadas em vez das leis integrais tradicionais porque melhoram o desempenho transitório do sistema e aumentam a robustez perante distúrbios externos na entrada da planta. Esta pesquisa objetiva desenvolver um controlador adaptativo backstepping a estrutura variável (Variable Structure Adaptive Backstepping Controller, VS-ABC) utilizando observadores de estado para plantas monovariáveis, lineares e invariantes no tempo com grau relativo unitário. Para isso, os filtros foram substituídos por um Observador Adaptativo de Luenberger e o algorítmo de controle utiliza leis chaveadas. As simulações apresentadas comparam o desempenho do controlador quando as variáveis de estado são estimadas por um observador, com o caso em que as variáveis estão disponíveis para medição.

10
  • JOSE ANICETO DUARTE COSTA
  • Desenvolvimento de um Sistema de Automação e Supervisão de Máquinas Dispensadoras através da Internet
  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • PABLO JAVIER ALSINA
  • ANDRES ORTIZ SALAZAR
  • FILIPE DE OLIVEIRA QUINTAES
  • Data: Apr 13, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como proposta o desenvolvimento de um sistema de controle e monitoramento de máquinas dispensadora, tendo como base uma Unidade Central de Processamento com periférico de comunicação através da internet. Acoplado às máquinas dispensadoras de preservativos masculinos, um módulo de aquisição de dados coletará e enviará, de forma imediata, as informações para os órgãos governamentais da saúde. Diante disso, tais órgãos poderão analisar os dados estatisticamente e compará-los com os índices de redução das DST/AIDS nas respectivas regiões de implantação dessas máquinas dispensadoras. No que tange à metodologia, cuida-se de um artigo de pesquisa explicativa e bibliográfica, com vertente metodológica quali-quantitativa, apresentando método de abordagem dedutivo e técnica de pesquisa de documentação indireta. No que concerne aos resultados das oitocentos e dezesseis simulações, pudemos concluir que ocorreram como esperado.

    

11
  • RICARDO CESAR DE OLIVEIRA MOREIRA
  • Antenas Planares Integradas com FSSs para Aplicações em Sistemas de Comunicações sem Fio

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • LAERCIO MARTINS DE MENDONCA
  • RONALDO DE ANDRADE MARTINS
  • Data: Apr 18, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho apresenta uma investigação teórica e experimental sobre as propriedades das antenas de microfita integradas com superfícies seletivas em frequência (Frequency Selective Surface – FSS). A integração se dá por meio da inserção da FSS no plano de terra da antena patch de microfita. Essa integração visa a melhoria de algumas características das antenas. As FSS utilizam elementos do tipo patch quadrado nas células unitárias.

    Especificamente, os resultados simulados são obtidos utilizando-se o programa computacional comercial CST Studio Suite® versão 2011. A partir de uma antena padrão, projetada para operar em sistemas de comunicações sem fio dos padrões IEEE 802.11 a/b/g/n as dimensões da FSS são variadas de forma a obter uma otimização de alguns parâmetros da antena, como casamento de impedância e seletividade nas bandas de operação.

    Após a otimização dos parâmetros investigados, são construídos dois protótipos de antenas patch de microfita com e sem a FSS no plano de terra. São feitas comparações dos resultados simulados com os resultados experimentais obtidos pelo analisador de rede ZVB 14 da Rohde & Schwarz®. A comparação visa validar a as simulações efetuadas e mostrar as melhorias obtidas com a FSS integrada no plano de terra da antena. Na construção dos protótipos, foram utilizados substratos dielétricos da Rogers Corporation do tipo RT-3060 com permissividade relativa igual a 10,2 e baixa tangente de perdas. Sugestões de continuidade do trabalho são apresentadas.

12
  • JOSE KLEBER COSTA DE OLIVEIRA
  • Controle Inteligente de Pressão Para uma Rede Sem Reservatório de Abastecimento Urbano de Água

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRES ORTIZ SALAZAR
  • JOSÉ VIEIRA DE FIGUEIREDO JUNIOR
  • Data: May 4, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • As empresas de saneamento do Brasil têm um grande desafio para o século XXI, procurar diminuir o índice de desperdícios físicos (água, produtos químicos e energia elétrica) e financeiros causados pela ineficiência operacional dos sistemas de abastecimentos de água potável, levando-se em consideração que atualmente já se enfrenta, em alguns casos, a escassez dos recursos hídricos. Os sistemas de abastecimentos estão cada vez mais complexos porque buscam minimizar os desperdícios e ao mesmo tempo atender melhor ao crescente número de usuários. Contudo, a evolução tecnológica está presente para diminuir a complexidade dos desafios hora impostos pela necessidade de contemplar os usuários com maior qualidade e eficiência nos serviços. Um dos grandes desafios para as empresas de abastecimentos de água está em proporcionar um serviço de boa qualidade contemplando a diminuição das despesas com energia elétrica. Diante disso, desenvolveu-se um trabalho de pesquisa através de um método que busca controlar a pressão da rede de distribuição em sistemas que não apresentam na sua configuração o reservatório e que por isso a água sai do poço diretamente para a rede de distribuição. O método de controle da pressão (controle inteligente) utiliza a lógica fuzzy para eliminar o desperdício de energia elétrica e os vazamentos provocados pela produção das bombas que injetam diretamente na rede de distribuição, provocando desperdício de energia quando o consumo das residências é reduzido causando o saturamento da rede. Esse trabalho foi realizado no condomínio Green Club II, situado na cidade de Parnamirim - RN, com o objetivo de estudar o comportamento da pressão da bomba que injeta diretamente na rede de distribuição. O estudo só foi possível em virtude da necessidade que havia de se encontrar uma solução para alguns vazamentos existentes na rede de distribuição e nos ramais das residências do respectivo condomínio, fato que despertou o interesse em desenvolver um trabalho com o intuito de realizar as experiências contidas nesta pesquisa.

13
  • TIAGO COSTA DE ARAUJO
  • Estudo e Projeto de Filtro Interdigital para Aplicação no Transponder do Satélite ITASAT

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RONALDO DE ANDRADE MARTINS
  • JEFFERSON COSTA E SILVA
  • Data: May 7, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O ITASAT é um projeto que visa a construção de um satélite de caráter experimental universitário para integrar a constelação de satélites do Sistema Brasileiro de Coleta de Dados, reunindo esforços de diversas instituições do Brasil, incluindo a AEB, o ITA, o INPE/CRN e a UFRN. Este documento demonstra o trabalho realizado para este projeto, com foco no desenvolvimento do primeiro estágio de filtragem na recepção do Transponder do Satélite ITASAT e sua integração com o sistema. Foram estudadas algumas arquiteturas de Filtro em Microfita, em busca da viabilidade de implementação e aplicação, restando-se apenas a arquitetura Interdigital como única estrutura viável de filtro em Microfita para o transponder, por sua economia de espaço na frequência de operação (UHF inferior). Adicionalmente, foram desenvolvidas duas novas arquiteturas completamente aplicáveis ao Transponder ITASAT, onde cada uma apresenta uma vantagem diferente. Todos os filtros foram construídos e medidos em laboratório, e suas performances foram comparadas.

    O ITASAT é um projeto que visa a construção de um satélite de caráter experimental universitário para integrar a constelação de satélites do Sistema Brasileiro de Coleta de Dados, reunindo esforços de diversas instituições do Brasil, incluindo a AEB, o ITA, o INPE/CRN e a UFRN. Este documento demonstra o trabalho realizado para este projeto, com foco no desenvolvimento do primeiro estágio de filtragem na recepção do Transponder do Satélite ITASAT e sua integração com o sistema. Foram estudadas algumas arquiteturas de Filtro em Microfita, em busca da viabilidade de implementação e aplicação, restando-se apenas a arquitetura Interdigital como única estrutura viável de filtro em Microfita para o transponder, por sua economia de espaço na frequência de operação (UHF inferior). Adicionalmente, foram desenvolvidas duas novas arquiteturas completamente aplicáveis ao Transponder ITASAT, onde cada uma apresenta uma vantagem diferente. Todos os filtros foram construídos e medidos em laboratório, e suas performances foram comparadas.

    O ITASAT é um projeto que visa a construção de um satélite de caráter experimental universitário para integrar a constelação de satélites do Sistema Brasileiro de Coleta de Dados, reunindo esforços de diversas instituições do Brasil, incluindo a AEB, o ITA, o INPE/CRN e a UFRN.

                Este documento demonstra o trabalho realizado para este projeto, com foco no desenvolvimento do primeiro estágio de filtragem na recepção do Transponder do Satélite ITASAT e sua integração com o sistema. Foram estudadas algumas arquiteturas de Filtro em Microfita, em busca da viabilidade de implementação e aplicação, restando-se apenas a arquitetura Interdigital como única estrutura viável de filtro em Microfita para o transponder, por sua economia de espaço na frequência de operação (UHF inferior). Adicionalmente, foram desenvolvidas duas novas arquiteturas completamente aplicáveis ao Transponder ITASAT, onde cada uma apresenta uma vantagem diferente. Todos os filtros foram construídos e medidos em laboratório, e suas performances foram comparadas.

    Existem muitas maneiras de melhorar rejeições espúria em frontend de satélites, mas na maioria dos casos há um problema que transforma a solução impraticável para o transponder do Itasat: a dimensão física. Este trabalho mostra o estudo e projeto de filtros interdigitais para melhorar essa rejeição espúria sem alterar a ordem do filtro nem aumentar suas dimensões físicas. O Filtro interdigital de microfita foi escolhido porque a ocupa pouco espaço no transponder do Itasat para a frequência de recepção desejada (401,65 MHz), e também devido à supressão da segunda harmônica. Esse filtro, devido ao terra e ao seu comprimento (um quarto de onda) garante uma maior rejeição espúria sem aumentos nas dimensões físicas. Diversas geometrias foram consideradas, incluindo geometrias fractais, para o projeto do filtro.

14
  • ANDRÉ FELIPE OLIVEIRA DE AZEVEDO DANTAS
  • IDENTIFICAÇÃO E COMPARAÇÃO ENTRE CONTROLE PREDITIVO COM MODELO NÃO LINEAR E PID EM SISTEMA DE SEPARAÇÃO GRAVITACIONAL DE ÁGUA-ÓLEO SINTONIZADOS COM PSO

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ALLAN DE MEDEIROS MARTINS
  • CARLOS EDUARDO TRABUCO DOREA
  • DANIELLE SIMONE DA SILVA CASILLO
  • Data: May 18, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Como um dos processos convencionais de tratamento primário de petróleo é possível encontrar na bibliografia os métodos que utilizam o separador trifásico acoplado a hidrociclones. Esses métodos de tratamento são importantes devido a necessidade de extração dos contaminantes mais indesejados no processo de produção do petróleo, a água, e ao mesmo tempo, a concentração de óleo na água deve ser mínima (da ordem de 40 a 20ppm) para o descarte regular da fase aquosa ao mar. A partir dessa necessidade de tratamento primário objetiva-se, neste trabalho, estudar e implementar algoritmos de identificação para modelos polinomiais NARX em malha fechada, aplicando os métodos MQR, ERR, AIC, e comparar estratégias de controle PI e preditivo utilizando os modelos NARX atualizados online em uma combinação de separador trifásico em série com três baterias de hidrociclones. Os objetivos principais deste trabalho são obter um processo otimizado de separação trifásica que regule o sistema, mesmo na presença de golfadas; mostrar que é possível obter sintonias otimizadas para os controladores analisando a malha como um todo; e, avaliar e comparar as estratégias de controle PI e preditivo aplicadas ao processo. Para cumprir estes objetivos foi ultilizado um simulador para representar o separador trifásico e os hidrociclones, além de desenvolvidos algoritmos de identificação de sistemas (NARX) utilizando MQR, aliados a métodos de detecção de estrutura de modelos. Também foram implementados algoritmos de controle preditivo com modelos NARX atualizado online, e algoritmos de otimização que utilizam PSO. O trabalho finaliza com a comparação de resultados obtidos a partir da utilização dos controladores PI e preditivo no sistema simulado ambos com estado otimizado através do algoritmo de nuvem de partículas, e concluindo que as otimizações realizadas tornam o regulatório menos sensível a perturbações externas (golfadas) e quando otimizados os dois controladores apresentam resultados similares, sendo a avaliação do preditivo um pouco menos sensível às perturbações.

15
  • JOBSON FRANCISCO DA SILVA
  • CONSTRUÇÃO E CONTROLE INTELIGENTE DE UM MANIPULADOR ROBÓTICO COM DOIS GRAUS DE LIBERDADE

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • PAULO HENRIQUE DE MIRANDA MONTENEGRO
  • Data: Jun 8, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O presente trabalho mostra o desenvolvimento e construção de um manipulador robótico de juntas rotativas com dois graus de liberdade, acionado por motores de indução trifásicos. O posicionamento do braço e da base é realizado por um controlador fuzzy, implementado no ambiente de programação LabVIEW®. O robô desenvolvido permite movimentação numa área espacial equivalente a um quarto de esfera. Resultados demonstraram a eficiência do controlador fuzzy quando solicitada a movimentação do braço para valores de referência.

16
  • ISAC CALISTRATO JACOME
  • Estudo Comparativo de Estratégias de Controle Aplicadas a um Gerador Síncrono

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • SAMAHERNI MORAIS DIAS
  • JOSÉ ÁLVARO DE PAIVA
  • Data: Jun 25, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A robustez e o desempenho do Controlador Adaptativo por Posicionamento de Polos e Estrutura Variável são avaliados neste trabalho, onde este controlador é aplicado para o controle de um Gerador Síncrono conectado a um barramento infinito. A avaliação da robustez deste controlador será realizada através de simulações, onde o algoritmo de controle foi submetido a condições adversas, tais como: perturbações,
    variações paramétricas e dinâmica não modelada. Também foi feita uma comparação desta estratégia de controle com outra utilizando controladores clássicos. Nas simulações, é utilizado o modelo acoplado do gerador síncrono, onde suas variáveis apresentam um alto grau de acoplamento, ou seja, se houver alteração em uma das variáveis de entrada do gerador as suas saídas serão alteradas simultaneamente. Os resultados das simulações demonstram qual estratégia de controle apresenta melhor desempenho, e é mais robusta a perturbações, variações paramétricas e dinâmica não modelada para o controle do Gerador Síncrono.

17
  • EDWIN LUIZE FERREIRA BARRETO
  • Estudo de Superfícies Seletivas de Frequência com o uso de inteligência computacional

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Jul 20, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho tem como objetivo principal efetuar a otimização do desempenho de estruturas de superfícies seletivas de frequência – FSS (Frequency Selective Surface), com patches condutores na forma de dipolos em cruz. A otimização foi realizada através da identificação de valores ótimos para a largura do dipolo e a periodicidade do arranjo, considerando o valor do comprimento do dipolo fixo. Especificamente, objetiva-se determinar valores que permitam aumentar a largura de banda, utilizando um algoritmo de busca bioinspirado com representação em números reais. As aplicações típicas de estruturas de FSS com patches condutores utilizam frequências selecionadas através das faixas de rejeição. As estruturas de FSS funcionam basicamente como filtros dependendo do tipo de elemento escolhido. A região do espectro eletromagnético escolhida para este estudo foi a faixa de 7 GHz a 12 GHz, que inclui basicamente a banda X. Essa região do espectro eletromagnético foi escolhida para possibilitar a medição do dispositivo com a utilização de antenas de abertura do tipo corneta, que operam na banda X. O projeto da FSS com a utilização do algoritmo genético – GA (Genetic Algorithm) permitiu aumentar a largura de banda da estrutura

18
  • GUSTAVO HENRIQUE SOUTO DA SILVA
  • Um Sistema de Visão Computacional para o Monitoramento de Parâmetros Respiratórios de Pacientes com Esclerose Lateral Amiotrófica em Ambiente Hospitalar

  • Advisor : RUMMENIGGE RUDSON DANTAS
  • COMMITTEE MEMBERS :
  • RUMMENIGGE RUDSON DANTAS
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • TATIANA AIRES TAVARES
  • Data: Jul 20, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A automação hospitalar está se expandido cada vez mais devido às necessidades do mercado e aos avanços tecnológicos no campo da Tecnologia da Informação. A busca por automatizar os processos na área de saúde é um problema presente tanto nos hospitais públicos quanto privados. Por isso, nos últimos anos, houve um aumento significativo de pesquisas na área de automação hospitalar, com o foco, no monitoramento de pacientes. O objetivo desse trabalho é desenvolver um sistema de visão computacional para monitorar, de forma remota, os parâmetros respiratórios de pacientes com Esclerose Lateral Amiotrófica – ELA em um ambiente hospitalar. Com base nos parâmetros respiratórios do paciente é possível determinar situações de risco para o mesmo. Quando uma situação de risco for detectada uma mensagem de alerta é enviada aos profissionais da saúde que trabalham junto ao paciente e à sua família. Esse sinal de alerta possibilita um atendimento ao paciente com mais rapidez e precisão.

19
  • FERNANDO HILTON TEIXEIRA FERREIRA
  • Automação Residencial Microcontrolada para Transmissão de Dados Via Rede Elétrica

  • Advisor : ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • MANOEL ALVES FILHO
  • Data: Jul 25, 2012


  • Show Abstract
  • A tecnologia da automação residencial utilizando a comunicação por rede elétrica, Power Line Communication (PLC), tem sido objeto de estudo e investigação nos últimos anos.  O crescente interesse desta tecnologia poderá ser justificado pela necessidade emergente de economia dos recursos energéticos e sua automatização da tecnologia residencial. Este trabalho trata da especificação e do desenvolvimento de um protocolo para controlar a comunicação entre dois microcontroladores (PIC), utilizando como meio de transmissão a rede elétrica (PLC), tornando a comunicação mais segura e ecomicamente viável. O protocolo será implementado em linguagem C, tendo como referência alguns protocolos desenvolvidos para o uso automobilístico.

20
  • JAILTON CARLOS DE PAIVA
  • e-Pontos: Uma solução embarcada de automação comercial aplicado a clubes de fidelidades baseado nas tecnologias RFID e smart card

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • CICILIA RAQUEL MAIA LEITE
  • HELIANA BEZERRA SOARES
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Jul 27, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Em praticamente todos os mercados verticais e em cada região do globo, os comerciantes de fidelidade adotaram a tática de reconhecimento e recompensa para identificar, manter e aumentar o rendimento de seus clientes. Várias estratégias têm sido adotadas pelas empresas, e a mais popular entre elas é o programa de fidelidade, que exibe um clube de fidelidade para gerenciar essas recompensas. Mas o problema com os programas de fidelidade é que todos eles se tornaram muito semelhantes, exigindo dessa forma uma revigorarão nesse mercado com novas estratégias, táticas e tecnologia apoiadas pela inovação. Visando isto, o presente trabalho de mestrado visa desenvolver uma solução totalmente automatizada para identificar os clientes, transmitir seus pontos de fidelidade para um servidor central e oferecer serviços de interesse online. Dessa forma, oferecendo métodos mais simples, mais rápidos, mais convenientes e mais flexíveis de resgates de pontos. Para isso, foi desenvolvida uma plataforma de hardware com sistema embarcado e tecnologia RFID que será utilizada nos PCs dos lojistas, um smart card para acumular os pontos a cada compra e um servidor web, o qual disponibilizará serviços de interesse para os lojistas e os clientes conveniado ao clube.

21
  • JOÃO TEIXEIRA DE CARVALHO NETO
  • Controle Robusto Aplicado a um Conversor Buck-Boost em Sistemas Fotovoltaicos

  • Advisor : ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • COMMITTEE MEMBERS :
  • ALBERTO SOTO LOCK
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRES ORTIZ SALAZAR
  • LUÍS FERNANDO ALVES PEREIRA
  • Data: Jul 30, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A utilização de painéis fotovoltaicos para a produção de energia elétrica a partir do aproveitamento da energia solar, é uma forma para a qual países tropicais como o Brasil dispõem de recursos de grande abundância. Os painéis fotovoltaicos são conectados a conversores que servem para definir um estágio de potência para produção de energia elétrica. Normalmente quando o conversor funciona por algum tempo, seus componentes indutivos e capacitivos aquecem, causando um aumento na resistência de saída do conversor. Este problema leva o sistema a outro ponto de operação, contribuindo diretamente para a perda da potência fornecida pelo mesmo. O objetivo do trabalho é de empregar um controlador robusto de realimentação de estados em um conversor CC-CC Buck-Boost ligado a um painel fotovoltaico para que a mudança da resistência de seus componentes ou a diminuição da radiação solar no painel não comprometa a tensão de saída da planta e consequentemente não diminua a potência fornecida pela mesma.

22
  • XIANKLEBER CAVALCANTE BENJAMIM
  • Identificação Visual de Caixas de Medicamentos Usando Features Correspondentes 

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • ANGÉLICA FÉLIX DE CASTRO
  • Data: Jul 30, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho utiliza algoritmos de visão computacional relacionado as features na identificação de caixas de medicamentos para deficientes visuais. O sistema é para pes- soas que apresentam alguma enfermidade que comprometa sua visão, prejudicando a identificação do medicamento correto a ser ingerido. Utilizamos a câmera, disponível em vários dispositivos populares como computadores, televisores e celulares, para identi- ficar a caixa do medicamento correto através da imagem e áudio mostrando ao deficiente as informações sobre a medicação como a posologia, indicação e contra indicações da medicação. Para isso, utilizamos um modelo de detecção de objetos usando algoritmos para identificar as features das caixas pela a imagem da caixa e exibição do áudio do me- dicamento da comparando o tempo que cada deficiente visual identifica a sua medicação e os benefícios que o sistema traz. Fazer uso dessa tecnologia pode ajudar várias pessoas com deficiência visual a tomarem o medicamento certo na hora indicada previamente pelo médico. Os experimentos realizados com 15 pessoas 93% acreditam que o sistema é útil e muito útil para identicar os medicamentos pelas caixas. 

23
  • TÚLIO DE PAIVA MARQUES CARVALHO
  • ISE-SPL: Uma Abordagem Baseada em Linha de Produtos de Software Aplicada à Geração Automática de Sistemas para Educação Médica na Plataforma E-learning

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • GLAUCIO BEZERRA BRANDAO
  • CRISTINE MARTINS GOMES DE GUSMÃO
  • Data: Aug 3, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Iniciada nas décadas de 1960 e 1970, a chamada revolução digital se intensificou com a disseminação da Internet em meados dos anos 1990, provocando significativas mudanças nas mais diversas atividades humanas. Tal revolução incrementou as alterações iniciadas pela difusão dos computadores nos processos produtivos, no mercado de trabalho, nas empresas e organizações, na produção cultural, nas relações sociais e na educação. Os impactos da internet foram tão grandes que a maior parte das atividades humanas atualmente dela não pode se isentar. Permeado por este fenômeno, ou novo paradigma social, o e-learning, também conhecido como educação à distância, surge como uma forma complementar de ensino, apresentando algumas vantagens como: aumento da acessibilidade da informação, aprendizado personalizado, democratização do ensino e facilidade de atualização, distribuição e padronização do conteúdo. Neste sentido, essa proposta de dissertação de mestrado tem como objeto o desenvolvimento de uma LPS (Linhas de Produto de Software), cujo propósito é a geração automática de sistemas e-learning para educação medica. Desta modo, criando um instrumento transversal, visto que este trabalho está na interseção de três áreas: educação, medicina e tecnologia da informação e comunicação. Com isso, a contribuição mais significativa dessa proposta é o desenvolvimento de uma metodologia inovadora para a educação medica que visa auxiliar o docente de medicina na sua prática pedagógica por meio do uso de tecnologias educacionais.

24
  • ARTHUR SALGADO DE MEDEIROS
  • Desenvolvimento de Software para Simulação de Motores com Dispositivos de Partida Baseada na Integração do ATP com o TOpReDE

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • JOSE TAVARES DE OLIVEIRA
  • CLOVIS BOSCO MENDONCA OLIVEIRA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Aug 3, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O transitório que envolve a partida de motores de médio e grande porte ligados no sistema elétrico das concessionárias distribuidoras de energia elétrica tem se situado principalmente nos casos em que essas cargas estão localizadas em pontos mais remotos dos alimentadores, no conjunto dos principais problemas a serem resolvidos, dados os efeitos que as partidas dessas cargas impõem à qualidade do fornecimento de energia elétrica dos consumidores.O Software desenvolvido tem o objetivo de realizar a interação entre os softwares TOpReDE e ATP de forma que as redes de distribuição de energia elétrica contidas no banco de dados do TOpReDE - Técnicas de Otimização para Redes de Distribuição de Energia Elétrica (Programa desenvolvido, entre 2004 e 2005, pela base de pesquisa OSEE - Otimização em Sistemas de Energia Elétrica, que envolve professores dos departamento de Engenharia Elétrica e de Engenharia da Computação da UFRN) sejam convertidas para o formato de dados do ATP (AlternativeTransientProgram) – programa que permite a simulação de transitórios eletromagnéticos em redes polifásicas, para que seja possível adicionar a estas redes de distribuição: motores elétricos de indução, dispositivos de partida de motores, cargas com potência constante e equipamentos de medição com o objetivo de detectar e analisar previamente, tanto graficamente (através do software PlotXY) quanto sob a forma de relatórios, possíveis distúrbios causados a estas redes mediante a partida de motores.

25
  • FRANCISCO ARY ALVES DE SOUZA
  • Análise de desempenho da rede neural artificial do tipo multilayer perceptron na era multicore

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • ALLAN DE MEDEIROS MARTINS
  • DANNIEL CAVALCANTE LOPES
  • Data: Aug 7, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • As redes neurais artificiais geralmente são aplicadas na solução de problemas complexos. Em problemas com maior complexidade ao aumentar o número de camadas e de neurônios é possível conseguir uma maior eficiência funcional, porém, isto acarreta em um maior esforço computacional. O tempo de resposta é um fator importante na decisão
    de usá-la em determinados sistemas. Muitos defendem que o maior custo computacional está na fase de treinamento. Porém, esta fase é realizada apenas uma única vez. Já treinada é necessário usar os recursos computacionais existentes de forma eficiente. Diante da era multicore o problema se resume à utilização eficiente de todos os núcleos de processamento disponíveis. No entanto, é necessário considerar a sobrecarga existente nas aplicações paralelas, neste sentido, esse trabalho propõe uma estrutura modular que mostrou-se ser mais adequado para as implementações paralelas. Neste é proposto paralelizar o processo feedforward (passo para frente) de uma RNA do tipo MLP, implementada com o OpenMP em uma arquitetura computacional de memória compartilhada. A investigação se dará com a realização de testes e análises dos tempos de execução. O speedup, a eficiência e a escalabilidade são analisados. Na proposta apresentada é possível percebe que ao diminuir o número de conexões entre os neurônios remotos o tempo de resposta da rede diminui e por consequência o tempo total de execução. O tempo necessário para comunicação e sincronismo está diretamente ligado ao número de neurônios remotos da rede, sendo então, necessário observar sua melhor distribuição.

26
  • ANTONIO PÉRICLES BONFIM SARAIVA DE OLIVEIRA
  • *

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • LUIZ EDUARDO CUNHA LEITE
  • RICARDO CORDEIRO DE FARIAS
  • Data: Aug 13, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • *

27
  • GIANCARLOS COSTA BARBOSA
  • Projeto de um Transformador utilizado em uma Planta de Plasma

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALBERTO SOTO LOCK
  • ANDRES ORTIZ SALAZAR
  • FILIPE DE OLIVEIRA QUINTAES
  • JOSSANA MARIA DE SOUZA FERREIRA
  • Data: Aug 13, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A contaminação do ambiente é uma questão que diz respeito a todos. O lixo tóxico é uma das principais causas de contaminação e uma solução global para eliminá-lo é o uso do plasma térmico. Atualmente, está em fase de desenvolvimento uma planta de inertização de lixo tóxico. Esta planta é composta, basicamente, por uma fonte de alimentação de radiofrequência (fonte RF) e uma tocha indutiva a plasma. Como a fonte de alimentação e a tocha apresentam uma diferença de impedâncias, faz-se necessário o uso de um transformador. Dessa forma, este trabalho apresenta a metodologia e o desenvolvimento de um transformador de média potência (50 kW) operando a alta frequência (400 kHz), utilizando ferramentas computacionais para os cálculos de campos eletromagnéticos.

28
  • NAIYAN HARI CANDIDO LIMA
  • Classificação de padrões através de um comitê de máquinas aprimorado por aprendizagem por reforço

  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • JORGE DANTAS DE MELO
  • Data: Aug 13, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A aprendizagem por reforço é uma técnica de aprendizado de máquina que, embora já te- nha encontrado uma grande quantidade de aplicações, talvez ainda não tenha alcançado seu pleno potencial. Uma das possibilidades que não foi devidamente testada até hoje foi a utili- zação da aprendizagem por reforço em conjunto com outros métodos para a solução de pro- blemas de classificação de padrões.

    É bem documentada na literatura a problemática que ensembles de máquinas de vetor de suporte encontram em termos de capacidade de generalização. Algoritmos como Adaboost não lidam com apropriadamente com os desequilíbrios que podem surgir nessas situações. Várias alternativas já foram propostas, com margens variadas de sucesso.

    Esta dissertação apresenta uma nova abordagem para a construção de comitês de máqui- nas de vetor de suporte. O algoritmo apresentado combina o algoritmo Adaboost com uma camada de aprendizagem por reforço, para ajustar parâmetros do comitê evitando que dese- quilíbrios nos classificadores componentes do comitê prejudiquem o desempenho de generali- zação da hipótese final. Foram efetuadas comparações de comitês com e sem essa camada adicional de aprendizagem por reforço, testando conjuntos de dados benchmarks amplamente conhecidos na área de classificação de padrões.

29
  • SINARA DA ROCHA MARTINS
  • Estudo Avaliativo de um Algoritmo Genético Auto-Organizável e Multiobjetivo utilizando Aprendizado de Máquina para Aplicações de Telecomunicações

  • Advisor : CLAUDIO RODRIGUES MUNIZ DA SILVA
  • COMMITTEE MEMBERS :
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • JOSE ALFREDO FERREIRA COSTA
  • SANDRO GONCALVES DA SILVA
  • ALEXANDRE DA COSTA PEREIRA
  • Data: Aug 15, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho apresenta um estudo avaliativo dos efeitos da utilização de uma técnica de aprendizado de máquina nas características principais de um algoritmo genético multiobjetivo e auto-organizável. Um algoritmo genético típico pode ser visto como uma técnica de busca que é normalmente aplicada em problemas que envolvem complexidade não polinomial.  Originalmente, estes algoritmos foram idealizados para criar métodos que buscam soluções aceitáveis (ótimos locais) para problemas em que os ótimos globais são inacessíveis ou são de difícil obtenção. À princípio, considerando apenas uma função de adaptação e um único objetivo de otimização. Hoje, entretanto, são comuns as implementações que não só consideram diversos objetivos de otimização simultaneamente (algoritmos multiobjetivos), mas também que permitem a alteração de diversos componentes do algoritmo dinamicamente (algoritmos auto-organizáveis). Além disso, são comuns também as combinações dos algoritmos genéticos com técnicas de aprendizado de máquina para melhorar algumas de suas características de desempenho e utilização. Neste trabalho, um algoritmo genético com recursos de aprendizado de máquina foi desenvolvido e analisado. A técnica de aprendizado de máquina utilizada foi uma variante de interpolação bicúbica, conhecida como Spline 2D. E sua aplicação foi feita para estimar o comportamento de uma função de fitness dinâmica, a partir do conhecimento obtido de um conjunto de experimentos realizados em laboratório. Esta função de fitness é também denominada de função de avaliação e é responsável pela determinação do grau de aptidão de uma solução candidata (indivíduo) em relação às demais de uma mesma população. O algoritmo pode ser aplicado em diversas áreas, inclusive no domínio das telecomunicações, como nos projetos de antenas e de superfícies seletivas de frequência. Neste trabalho em particular, o algoritmo apresentado foi desenvolvido para otimizar o projeto de uma antena de microfita comumente utilizada em sistemas de comunicação sem fio e projetada para aplicação em sistemas de banda ultra larga (Ultra Wideband - UWB). O protótipo de algoritmo final permitiu a otimização de duas dimensões da geometria da antena - a altura (Ls) e a Largura (Ws) de uma fenda no plano de terra com relação a três objetivos: largura de banda do sinal irradiado, perda de retorno e desvio da frequência central. As duas dimensões (Ls e Ws) são usadas como variáveis em três modelos diferentes de spline, uma para cada objetivo da otimização, para compor uma função de adaptação composta multiobjetiva. O resultado final proposto pelo algoritmo foi comparado com o resultado obtido de um programa simulador e com o resultado medido de um protótipo físico da antena construída em laboratório. No estudo apresentado, este protótipo foi analisado com relação ao seu grau de sucesso, no que diz respeito a quatro características importantes de um algoritmo genético multiobjectivo auto-organizável:  desempenho, flexibilidade, escalabilidade e exatidão dos resultados apresentados. Ao final do estudo, observou-se um ganho sensível com relação à flexibilidade e com relação à exatidão, embora tenha havido uma perda observável no que diz respeito ao desempenho e escalabilidade do algoritmo.  

30
  • DANIEL GUERRA VALE DA FONSECA
  • MODELAGEM E CONTROLE ADAPTATIVO DE UMA PLANTA DIDÁTICA DE NÍVEL COM INSTRUMENTAÇÃO INDUSTRIAL

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • LUÍS FERNANDO ALVES PEREIRA
  • Data: Aug 31, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Plantas didáticas são consideradas boas ferramentas para o ensino e aprendizado de controle de processos. Possibilitam o desenvolvimento de pesquisa em diversas áreas, como controle, instrumentação, automação, modelagem e identificação, proporcionando um contato direto com equipamentos semelhantes ou até mesmo usados no setor industrial. Em vista dessas capacidades, o objetivo deste trabalho consiste em modelar e controlar a planta didática T5552 (fabricante Amatrol), que constitui um sistema de controle de processo para vazão e nível com instrumentação industrial. Com o modelo foi possível construir um simulador capaz permitir estudos a respeito do funcionamento do sistema, sem os gastos com a operação do processo real. É o caso de experimentos com controladores, que podem ser testados diversas vezes antes de serem efetivamente utilizados no processo real. O controle mantém as variáveis dentro dos limites de operação desejados. Dentres os diversos tipos de controladores existentes, será dado foco aos de tipo adaptativo, principalmente ao auto-sintonizável direto (Direct Self-Tuning Regulator – DSTR) com ação integral e ao controlador com Escalonado de Ganho (Gain Schedule – GS). O controlador DSTR foi baseado no método de posicionamento de pólos e teve seus parâmetros estimados através da técnica dos mínimos quadrados recursivos. As características dos sistema adaptativo foram de grande valia para garantir um desempenho satisfatório do controlador,  quando aplicado à planta.
31
  • ALYNNE CONCEICAO SARAIVA DE QUEIROZ
  • Extração e Representação de Conhecimento de Séries Temporais de Demanda de Energia Elétrica

    Extração e Representação de Conhecimento de Séries Temporais de Demanda de Energia Elétrica usando o TSKR

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • DANIEL ALOISE
  • ILONEIDE CARLOS DE OLIVEIRA RAMOS
  • CARMELO JOSÉ ALBANEZ BASTOS FILHO
  • Data: Sep 24, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A abertura do mercado brasileiro de energia elétrica e a competitividade entre as empresas ligadas ao setor energético fazem com que a busca por informações úteis e ferramentas que venham a auxiliar na tomada de decisões, aumente por parte das concessionárias. Uma importante fonte de conhecimento para essas concessionárias são as séries temporais de demanda de energia. A identificação de padrões de comportamento e a descrição de eventos se tornam importantes para a execução de atividades de planejamento, buscando melhorias na qualidade de atendimento e vantagens financeiras.
    O presente trabalho expõe uma metodologia baseada em ferramentas de mineração e representação de séries temporais, com o objetivo de extrair conhecimento que relacionam as demandas de energia de diversas zonas de abastecimento de uma concessionária. O método utilizado tem como objetivo a descrição das relações temporais locais de séries temporais multivariadas, chamado de Time Series Knowledge Mining (TSKM), que explora as relações de duração, coincidência e seqüência de eventos. Assim, podemos extrair regras que descrevem a co-ocorrência de eventos nas séries de demanda de energia, de modo a oferecer uma linguagem de fácil compreensão sobre o sistema global. Para a representação desses dados será utilizada a linguagem Time Series Knowledge Representation (TSKR) que representa as relações temporais extraídas pelo TSKM de forma simbólicaA abertura do mercado brasileiro de energia elétrica e a competitividade entre as empresas do setor energético fazem com que a busca por informações úteis e ferramentas que venham a auxiliar na tomada de decisões, aumente por parte das concessionárias. Uma importante fonte de conhecimento para essas concessionárias são as séries temporais de consumo de energia. A identificação de padrões de comportamento e a descrição de eventos se tornam necessárias para a execução de atividades de planejamento, buscando melhorias na qualidade de atendimento e vantagens financeirasA abertura do mercado brasileiro de energia elétrica e a competitividade entre as empresas do setor energético fazem com que a busca por informações úteis e ferramentas que venham a auxiliar na tomada de decisões, aumente por parte das concessionárias. Uma importante fonte de conhecimento para essas concessionárias são as séries temporais de consumo de energia. A identificação de padrões de comportamento e a descrição de eventos se tornam necessárias para a execução de atividades de planejamento, buscando melhorias na qualidade de atendimento e vantagens financeiras.
    A abertura do mercado brasileiro de energia elétrica e a competitividade entre as empresas do setor energético fazem com que a busca por informações úteis e ferramentas que venham a auxiliar na tomada de decisões, aumente por parte das concessionárias. Uma importante fonte de conhecimento para essas concessionárias são as séries temporais de consumo de energia. A identificação de padrões de comportamento e a descrição de eventos se tornam necessárias para a execução de atividades de planejamento, buscando melhorias na qualidade de atendimento e vantagens financeiras.
    O presente trabalho expõe uma metodologia baseada em ferramentas de mineração e representação de séries temporais, com o objetivo de extrair conhecimento que relacionam séries de demanda de energia elétrica de diversas subestações interligadas de uma concessionária. O método utilizado explora relações de duração, coincidência e ordem parcial de eventos em séries temporais multivariadas. Para a representação do conhecimento extraído será utilizada a linguagem proposta por Mörchen (2005) chamada Time Series Knowledge Representation (TSKR).
    Foi realizado um estudo de caso usando séries temporais de demanda de energia de 8 subestações interligadas por um sistema em anel, que alimenta a região metropolitana de Goiânia-GO, cedidas pela CELG (Companhia Energética de Goiás), permissionária do serviço de distribuição de energia no estado de Goiás (Brasil).

    A abertura do mercado brasileiro de energia elétrica e a competitividade entre as empresas do setor energético fazem com que a busca por informações úteis e ferramentas que venham a auxiliar na tomada de decisões, aumente por parte das concessionárias. Uma importante fonte de conhecimento para essas concessionárias são as séries temporais de consumo de energia. A identificação de padrões de comportamento e a descrição de eventos se tornam necessárias para a execução de atividades de planejamento, buscando melhorias na qualidade de atendimento e vantagens financeiras.

    O presente trabalho expõe uma metodologia baseada em ferramentas de mineração e representação de séries temporais, com o objetivo de extrair conhecimento que relacionam séries de demanda de energia elétrica de diversas subestações interligadas de uma concessionária. O método utilizado explora relações de duração, coincidência e ordem parcial de eventos em séries temporais multivariadas. Para a representação do conhecimento extraído será utilizada a linguagem proposta por Mörchen (2005) chamada Time Series Knowledge Representation (TSKR).

    Foi realizado um estudo de caso usando séries temporais de demanda de energia de 8 subestações interligadas por um sistema em anel, que alimenta a região metropolitana de Goiânia-GO, cedidas pela CELG (Companhia Energética de Goiás), permissionária do serviço de distribuição de energia no estado de Goiás (Brasil).

     

    Foi realizado um estudo de caso usando séries temporais de demanda de energia de 8 subestações interligadas por um sistema em anel, que alimenta a região metropolitana de Goiânia-GO, cedidas pela CELG (Companhia Energética de Goiás), permissionária do serviço de distribuição de energia no estado de Goiás (Brasil).O presente trabalho expõe uma metodologia baseada em ferramentas de mineração e representação de séries temporais, com o objetivo de extrair conhecimento que relacionam séries de demanda de energia elétrica de diversas subestações interligadas de uma concessionária. O método utilizado explora relações de duração, coincidência e ordem parcial de eventos em séries temporais multivariadas. Para a representação do conhecimento extraído será utilizada a linguagem proposta por Mörchen (2005) chamada Time Series Knowledge Representation (TSKR).
    Foi realizado um estudo de caso usando séries temporais de demanda de energia de 8 subestações interligadas por um sistema em anel, que alimenta a região metropolitana de Goiânia-GO, cedidas pela CELG (Companhia Energética de Goiás), permissionária do serviço de distribuição de energia no estado de Goiás (Brasil
32
  • JESSÉ HANIEL DO NASCIMENTO BATISTA
  • Sistema de Teleoftalmologia para Auxílio ao Pré-Diagnóstico de Disfunções Oculomotoras

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCELO AUGUSTO COSTA FERNANDES
  • GLAUCIA REGINA MEDEIROS AZAMBUJA SIZILIO
  • Data: Oct 18, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A visão é um dos cinco sentidos do corpo humano e, em crianças, é responsável por até 80% da percepção do mundo ao redor. Segundo a Organização Mundial de Saúde, existem 1,5 milhão de crianças de 0 a 16 anos que possuem baixa visão e são consideradas cegas. Conhecida pelo nome de ambliopia dentro da medicina oftalmológica, a baixa visão (como é conhecida popularmente) é uma deficiência ocular causada pela má captura da imagem pela retina mesmo com o uso de lentes corretivas. O Ministério da Educação do Brasil aponta essa deficiência visual (dentre outras) como um grande desafio aos educadores de crianças, principalmente no processo de alfabetização. Visto que uma das causas da ambliopia é a descoordenação motora dos olhos, o diagnóstico pode ser feito com instrumentos eletrônicos que utilizam técnicas de processamento de imagens para a detecção do movimento dos olhos em tempo real. Esse rastreamento pode ser realizado de forma intrusiva ou não intrusiva em relação ao contato do equipamento com a pele e os olhos do usuário. Este trabalho apresenta uma proposta de sistema embarcado baseado em SOC ARM equipado com uma webcam para auxiliar como ferramenta de equipes itinerantes de saúde básica do governo federal no diagnóstico de deficiências visuais de causa motora, como a ambliopia.

33
  • THIAGO MEDEIROS BARROS
  • SUPERVISÓRIO INTELIGENTE DE PROCESSOS NA INDÚSTRIA DO PETRÓLEO E GÁS: APLICAÇÃO EM
    UMA COLUNA DE DESTILAÇÃO SIMULADA INTEGRADA A INSTRUMENTAÇÃO REAL.

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCIA MARIA LIMA DUARTE
  • FREDE DE OLIVEIRA CARVALHO
  • Data: Nov 12, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A necessidade de desenvolver uma arquitetura que promovesse a monitoração de softwares
    de simulação através de supervisórios, agregando módulos inteligentes e equipamentos como CLP's
    de acordo com necessidade do problema, foi a força motriz desse trabalho. No presente estudo será
    desenvolvido um supervisório inteligente sobre uma simulação modelada no Unisim. Será utilizado
    como comunicação entre o supervisório e o software de simulação o OLE Automation, o qual, junto
    ao uso de banco de dados, promoverá uma arquitetura de fácil manutenção e escalável. Agregando
    valor ao trabalho, serão desenvolvidos módulos inteligentes para pré-processamento e extração de
    características dos dados, e inferência de variáveis. Esses módulos terão como base principal o
    software Encog.

34
  • ADELSON LUIZ DE LIMA
  • Uma aplicação do algoritmo QT clustering para marcação colaborativa de pontos perigosos em vias públicas

  • Advisor : AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • COMMITTEE MEMBERS :
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ALLAN DE MEDEIROS MARTINS
  • GEORGE AZEVEDO DA SILVA
  • PAULO SERGIO DA MOTTA PIRES
  • Data: Dec 7, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O trabalho propõe um sistema colaborativo para marcação de pontos perigosos em vias de transporte e geração de alertas para motoristas. Ele consistira de um sistema de alerta de proximidade de um ponto de perigo, que será alimentado pelos próprios motoristas através de um aparelho móvel equipado com GPS. O sistema deverá consolidar dados fornecidos por vários motoristas diferentes e gerar um conjunto de pontos comum a ser usado no sistema de alerta. Embora a aplicação seja destinada à proteção de motoristas, os dados gerados por ela poderão servir de insumos para os órgãos responsáveis melhorarem a sinalização e recuperação de vias públicas.

35
  • PEDRO IVO DE ARAUJO DO NASCIMENTO
  • Obtenção dos Parâmetros-X de Estruturas Planares

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RONALDO DE ANDRADE MARTINS
  • JEFFERSON COSTA E SILVA
  • Data: Dec 11, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O grande desenvolvimento dos sistemas de comunicação nas últimas décadas, trouxe a necessidade de uma caracterização cada vez mais precisa dos componentes utilizados. A modelagem por meio de parâmetros-S é utilizada para caracterização, modelagem, simulação e testes de sistemas de comunicação desde meados dos anos 60. Contudo a limitação da modelagem dos parâmetros-S para sistemas lineares fez crescer a necessidade por novos tipos de modelagem que incluam as características de sistemas não lineares. A modelagem por distorção poli-harmônica é uma técnica de modelagem para sistemas não lineares que vem ganhando espaço na literatura por sua praticidade e semelhança conceitual com a modelagem por parâmetros-S. Este trabalho apresentará uma análise da modelagem por distorção harmônica, o desenvolvimento de um banco de testes para simulação de estruturas planares e a caracterização de estruturas planares por meio de parâmetros-X. Para com isso analisar a utilização, precisão e eficiência da modelagem por distorção poli-harmônica para estruturas planares.

36
  • ALUISIO IGOR REGO FONTES
  • Classificação Automática de Modulação Digital com uso de Correntropia para Ambientes de Rádio Cognitivo

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • FRANCISCO MARCOS DE ASSIS
  • Data: Dec 14, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Os modernos sistemas de comunicação sem fio empregam, frequentemente, técnicas adaptativas para proporcionar uma alta taxa de transmissão, enquanto asseguram qualidade de serviço (QoS) e abrangência de cobertura. Estudos recentes têm mostrado que esses sistemas podem se tornar ainda mais eficientes com a incorporação de técnicas de inteligência artificial e de conceitos de rádio definido por software. Os sistemas que seguem essa linha, conhecidos como Sistemas de Rádio Cognitivo, podem idealmente explorar de forma dinâmica e oportunística diferentes porções do espectro de frequências não utilizadas, conhecidas como buracos espectrais, com o objetivo de prover altas taxas de transmissão de dados com elevada confiabilidade e disponibilidade de serviço. A Classificação Automática de Modulação (AMC) seria uma habilidade muito útil nesses sistemas. Normalmente, as técnicas de AMC utilizam alguma forma de pré-processamento do sinal para extração de características que pode introduzir um alto custo computacional ou necessitar de suposições ideais, e até mesmo superficiais, sobre o sinal recebido. Este trabalho propõe o uso direto de uma medida de similaridade, baseada na Teoria da Informação, conhecida como coeficiente de correntropia, para se conseguir o reconhecimento automático de modulações digitais sem a necessidade de uma fase intermediária de extração de características. Experimentos realizados por meio de simulação computacional demonstram que a técnica proposta neste trabalho apresenta uma alta taxa de sucesso na classificação de modulações digitais, mesmo na presença de ruído aditivo gaussiano branco (AWGN).

37
  • ANTONIO DOS SANTOS DÁLIA
  • Dimensionamento de Sistemas de Aterramento em Linhas de Transmissão para Escoamento Eficiente de Correntes de Surtos Atmosféricos.

  • Advisor : JOSE TAVARES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • RICARDO FERREIRA PINHEIRO
  • FRANKLIN MARTINS PEREIRA PAMPLONA
  • Data: Dec 14, 2012


  • Show Abstract
  • Este trabalho propõe em ambiente simulado no ATP (Alternative Transient Program),a fim de obter o comprimento necessário de fio contrapeso capaz de evitar o fenômeno de backflashover nas cadeias de isoladores de Linhas de  Transmissão, para determinados valores de resistividade de solo e alguns tipos de disposição de sistemas de aterramento das estruturas.  

38
  • DIEGO ALVES FORMIGA
  • Estimação de fasores aplicada à proteção de linhas de transmissão de energia elétrica baseada em algoritmos recursivos lineares

  • Advisor : FABIANO FRAGOSO COSTA
  • COMMITTEE MEMBERS :
  • FABIANO FRAGOSO COSTA
  • FLAVIO BEZERRA COSTA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • SAMUEL XAVIER DE SOUZA
  • KLEBER MELO E SILVA
  • Data: Dec 18, 2012


  • Show Abstract
  • Neste trabalho, propõe-se uma nova técnica de estimação fasorial, a ser utilizada em relés digitais para proteção de distância de linhas de transmissão, baseada no método dos mínimos quadrados e denominada de mínimos quadrados em caminhada aleatória modificada. Os métodos de estimação fasorial tem seu desempenho deteriorado devido principalmente, a componente DC de decaimento exponencial presente nas correntes de falta. No intuito de reduzir a intensidade da interferência da componente DC, agregou-se ao método de mínimos quadrados um filtro morfológico aplicado previamente ao processo de estimação fasorial. O método apresentado foi implementado em ambiente MATLABr e o seu desempenho comparado aos métodos convencionais de estimação fasorial, também baseados em mínimos quadrados, e ao algoritmo de Fourier de um ciclo. Os métodos baseados na técnica de mínimos quadrados utilizados para comparação com o método proposto foram: recursivo ponderado, com reinicialização da covariância e caminhada aleatória. As análises das técnicas foram realizadas por meio de sinais sintéticos e sinais oriundos de simulações no Alternative Transient Program (ATP). Em comparação aos demais métodos de estimação fasorial, o método apresentado obteve resultados satisfatórios no que se refere à velocidade de resposta, oscilação em regime permanente e percentual de overshoot. Finalmente, a resposta do método proposto à variações nos parâmetros de falta também foi analisada no que se refere à trajetória da impedância aparente e distância estimada da falta.

39
  • JOÃO PAULO FERREIRA GUIMARÃES
  • Controle de Atitude e Altitude Para um Veículo Aéreo Não Tripulado do Tipo Quadrotor

  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • CARLOS EDUARDO TRABUCO DOREA
  • PABLO JAVIER ALSINA
  • SILVIA SILVA DA COSTA BOTELHO
  • Data: Dec 19, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Um Quadrotor é um Veículo Aéreo Não Tripulado (VANT) dotado de quatro rotores distribuídos nas extremidades de uma estrutura mecânica simples em forma de "X".

    O objetivo desse trabalho é construir e estabilizar uma aeronave desse tipo, com alta capacidade de carga, em uma determinada altitude, sob ângulos de rolagem, guinada e arfagem pré-definidos.

    A abordagem de controle de estabilização baseia-se numa transformação das variáveis de entrada do sistema afim de realizar o controle de forma desacoplada. A estratégia proposta se baseia na divisão do problema de controle em dois níveis hierárquicos: o nível inferior, objeto deste trabalho, mantém os ângulos e a altitude do veículo em valores desejados, enquanto o nível superior estabelece referências adequadas para o nível inferior, de forma a executar os movimentos desejados.

    Uma arquitetura de hardware e software foi especialmente desenvolvida e implementada para um protótipo experimental usado para testar e validar a abordagem de controle proposta.

     

40
  • RAFAELLE DE AGUIAR CORREIA
  • Controle Fuzzy Espacialmente Diferenciado para um Sistema de Irrigação

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRE LAURINDO MAITELLI
  • OSCAR GABRIEL FILHO
  • Data: Dec 20, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Projetos de irrigação tradicionais não controlam localmente a disponibilidade de água no solo.
    Assim, podem ocorrer ciclos irregulares de irrigação: alguns insuficientes, o que provoca déficit
    de água; outros em demasia, o que causa falta de oxigenação nas plantas. Devido à natureza
    não-linear do problema e do ambiente multivariável de processos de irrigação, a lógica
    fuzzy é sugerida como substituta aos sistemas comerciais de irrigação tipo ON-OFF com temporização
    pré-definida. Outra limitação das soluções comerciais é que os processos de irrigação
    não atendem às diferentes necessidades hídricas dos ciclos de crescimento das culturas
    nem às mudanças nas variáveis climáticas. Dessa maneira, para atender necessidades agrícolas
    baseadas em localização, é indicado monitorar dados ambientais usando sensores sem fio,
    interligados a um sistema de controle inteligente. Isso é mais evidente em aplicações de agricultura
    de precisão. Este trabalho apresenta o desenvolvimento teórico e experimental de um
    sistema de controle fuzzy espacialmente diferenciado para um sistema de irrigação, baseado
    no sensoriamento da umidade do solo com sensores sem fio. A arquitetura do sistema de controle
    é modular: um subsistema fuzzy central determina o set point de umidade do solo da região
    de atuação do nó sensor (de acordo com o conjunto solo-planta-clima) e um subsistema
    fuzzy, embarcado no nó sensor, faz o controle servo e atua no sistema de irrigação. O sistema
    de controle fuzzy foi simulado com a ferramenta de programação SIMULINK® e foi construído
    experimentalmente como sistema embarcado em um dispositivo móvel SunSPOTTM operando
    com ZigBee. Modelos de controladores foram desenvolvidos e avaliados em diferentes
    combinações de variáveis de entrada e base de regras de inferência.

41
  • DESNES AUGUSTO NUNES DO ROSARIO
  • ESCALABILIDADE PARALELA DE UM ALGORITMO DE MIGRAÇÃO REVERSA NO TEMPO (RTM) PRÉ-EMPILHAMENTO

  • Advisor : SAMUEL XAVIER DE SOUZA
  • COMMITTEE MEMBERS :
  • SAMUEL XAVIER DE SOUZA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ROSANGELA CORREA MACIEL
  • JESSÉ CARVALHO COSTA
  • Data: Dec 21, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O estudo sísmico é uma área de extrema importância na geofísica. Associada principalmente à exploração de petróleo, essa linha de pesquisa concentra boa parte de todo o investimento realizado nessa grande área. Dessa maneira, o processamento sísmico evoluiu significativamente nos últimos anos devido às demandas da indústria petrolífera e ao estudo de novos algoritmos. Uma atividade de suma importância nesse contexto é o imageamento de subsuperfícies, que é iniciado através dos levantamentos sísmicos realizados na superfície da terra ou do mar. Em seguida, realiza-se um processamento constituído por diversas etapas, visando além da eliminação de eventos indesejáveis, a obtenção de uma imagem das subsuperfícies em um tempo viável. Dentre estas diversas etapas desse processamento, a migração tem como objetivo a obtenção de uma seção sísmica que represente de forma precisa e fiel as estruturas geológicas contidas nos dados. O resultado de um algoritmo de migração é uma imagem 2D ou 3D que torna possível a identificação de falhas, domos salinos, reservatórios petrolíferos e muitos outros eventos sísmicos. Entretanto, uma migração sísmica rica em qualidade e precisão pode ser um processo demasiadamente longo, devido às heurísticas matemáticas do algoritmo e à quantidade extensa de entradas e saídas de dados envolvida neste processo, podendo levar dias, semanas e até meses de execução ininterrupta em supercomputadores. Tendo como objetivo a melhoria de desempenho, este trabalho apresenta a paralelização do núcleo do algoritmo de Migração Reversa no Tempo (RTM - do inglês: Reverse Time Migration), utilizando o modelo de programação paralela OpenMP (do inglês: Open Multi-Processing). Devido à continua evolução do ramo de processamento paralelo, foram realizadas análises de desempenho tais como a de speedup, de eficiência, e, por fim, a identificação do grau de escalabilidade algorítmica com relação ao avanço tecnológico esperado por futuros processadores.

Thesis
1
  • JOAO CARLOS XAVIER JUNIOR
  • NatalGIS: Um Sistema Multiagente de Recomendação de Informações Geográficas Baseado em Agrupamento de Dados Relacionais

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRÉ CARLOS PONCE DE LEON FERREIRA DE CARVALHO
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • VALERIA GONCALVES SOARES
  • Data: Feb 3, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Devido a grande quantidade de informação existente nos dias atuais, os sistemas baseados na web que manipulam grande volume de dados enfrentam diariamente o dilema de apresentar de maneira eficiente informações relevantes aos seus usuários. Motivado por esse fato, nosso trabalho apresenta o NatalGIS, que é um sistema multiagentes para recomendação de informações geográficas. O sistema permite que os usuários possam guardar as informações visualizadas em seus próprios históricos de acesso, estruturados para tal, em um banco de dados relacionais. Baseado nesse histórico, o sistema cria agrupamentos de informações relevantes através do uso de métodos de agrupamento de dados relacionais. Através das informações guardadas no perfil dos usuários, os agentes inteligentes podem interagir e recomendar informações geográficas relevantes aos usuários. O processo de recomendação está diretamente baseado nos grupos formados a partir dos históricos de acessos dos usuários e das preferências indicadas por eles. De posse disto, os agentes de recomendação são capazes de criar focos de atenção específicos para cada usuário, que serão baseados no grupo no qual o usuário pertence e nas preferências indicadas pelo próprio usuário. O uso de agrupamentos de dados relacionais no processo de recomendação de informações geográficas reduz consideravelmente o tempo de recuperação, visto que não há a necessidade de recuperá-los diretamente de uma grande base de dados geográficos. Por último, para que fosse possível a utilização de métodos de agrupamentos no processo de recomendação, nós propomos neste trabalho dois métodos de trabalhar com dados relacionais, onde um deles está relacionado a uma alternativa para a organização dos dados e o outro é um método simples para agrupar os dados relacionais. Para analisar a viabilidade destes dois métodos, fizemos uma análise de desempenho desses métodos, comparando-os com dois métodos existentes na literatura. Os resultados iniciais foram promissores e resolvemos fazer uma análise com outras bases de dados relacionais. O melhor método, dentre as diversas bases de dados e critérios avaliados, foi sempre um dos métodos propostos neste trabalho.

2
  • WILFREDO BLANCO FIGUEROLA
  • Dinâmica da Plasticidade Sináptica em neurônios do Hipocampo durante ciclos de sono: um estudo computacional

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • EMILIO DEL MORAL HERNANDEZ
  • MAURO COPELLI
  • SIDARTA TOLLENDAL GOMES RIBEIRO
  • Data: Mar 26, 2012


  • Show Abstract
  • Tem sido proposto que o papel cognitivo do sono se deriva de um redimensionamento global não Hebbiano dos pesos sinápticos, típico de sono de ondas lentas (SOL ou SWS para slow-wave sleep em inglês), e capaz de homeostaticamente restabelecer a capacidade de aprender coisas novas, apagando memórias durante a noite. Outro ponto de vista postula que o sono desencadeia um realce das coneções sinápticas, entendida como a combinação de ambos não Hebbian “rescaling” e Hebbian “upscaling” de pesos sinápticos em circuitos complementares, levando à melhoria da memória seletiva ou de reestruturação. Na transição do SWS para o estagio de movimento rápido dos olhos (MRO ou REM para rapid-eye-movement sleep inglês) tem sido proposto para induzir “upscaling”, possivelmente devido às grandes diferenças entre os regimes das taxas de disparos entre os estados, ou por causa da regulação positiva de fatores envolvidos na plasticidade da memória de longo prazo. Foram comparadas as teorias da homeostase e do realce usando uma rede neural artificial (RNA ou ANN para Artifitial Neural Network em inglês), alimentada com os dados registrados do hipocampo de ratos durante todo o ciclo vigília-sono. Na simulação onde a ANN não aplicou os mecanismos de plasticidade de longo prazo durante o sono, pesos sinápticos foram inexoravelmente re-escalados a uma velocidade proporcional à taxa de disparo, eventualmente, apagando qualquer padrão de pesos sinápticos previamente estabelicidos. Em contraste, quando plasticidade de longo prazo foi modelada durante a transição SWS para REM, o um aumento dos pessos sinapticos foi observado em toda a gama de seus valores, efetivamente redistribuindo-los de modo que reforça um subconjunto de sinapses ao longo do tempo. Os resultados mostram que uma
    regulação positiva proveninte de da plasticidade a longo prazo podem alterar completamente o papel do sono: sua ausência leva ao esquecimento, a sua presença leva a uma mudança mnemônica positiva .

3
  • GLAUCIA REGINA MEDEIROS AZAMBUJA SIZILIO
  • Método Fuzzy para Auxílio ao Diagnóstico de Câncer de Mama em Ambiente Inteligente de Telediagnóstico Colaborativo para Apoio à Tomada 
    de Decisão.
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • CELSO ALBERTO SAIBEL SANTOS
  • JORGE DANTAS DE MELO
  • PEDRO FERNANDES RIBEIRO NETO
  • Data: May 14, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O câncer de mama, apesar de ser uma das principais causas de morte entre as mulheres em todo o mundo, é uma doença que pode ser curada se for diagnosticada precocemente. Uma das principais técnicas utilizadas na detecção de câncer de mama é a Fine Needle Aspirate – FNA (ou Punção Aspirativa por Agulha Fina) que, dependendo do caso clínico, necessita da análise de vários médicos especialistas para a efetivação do diagnóstico. Entretanto, a realização de tais diagnósticos e a emissão de segundos pareceres têm sido prejudicadas pela dispersão geográfica dos médicos e/ou a dificuldade na conciliação de tempo para realizar trabalhos em conjunto. Inserindo-se nessa realidade, esta tese de doutorado utiliza inteligência computacional no apoio à tomada de decisão médica para a realização de telediagnósticos. Para tanto apresenta um método fuzzy destinado a auxiliar o diagnóstico de câncer de mama, capaz de processar e classificar dados extraídos de esfregaços de tecidos mamários obtidos por FNA. Este método está integrado a um ambiente virtual para realização de telediagnóstico colaborativo, cujo modelo foi desenvolvido prevendo a incorporação de Módulos de Pré-Diagnóstico para apoio à tomada de decisão médica. No desenvolvimento do método fuzzy, o processo de aquisição do conhecimento foi realizado pela extração e análise dos dados numéricos em base de dados padrão ouro e por entrevistas e discussões com médicos especialistas. O método foi testado e validado com casos reais e, em função da sensibilidade e da especificidade alcançadas (diagnóstico correto de tumores, respectivamente, malignos e benignos), os resultados obtidos foram satisfatórios, considerando tanto os pareceres de médicos quanto a comparação com outros estudos realizados envolvendo diagnóstico de câncer de mama por FNA.

4
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • DISPOSITIVOS PLANARES INTEGRADOS UTILIZANDO MÉTODO DINÂMICO COM METAMATERIAIS E PBG

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • ELIALDO CHIBERIO DA SILVA
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOSE PATROCINIO DA SILVA
  • Data: May 18, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Esta tese apresenta várias pesquisas, incluindo as análises teóricas e numéricas, dos parâmetros de uma antena de microfita do tipo retangular, sobre substrato EBG/PBG (Eletromagnetic/Photonic Band Gap). É aplicada a teoria de onda completa do método da Linha de Transmissão Transversa - LTT, para a obtenção das equações gerais dos campos eletromagnéticos das estruturas. É obtida a frequência de ressonância complexa usando em conjunto o método dos momentos como o LTT. São desenvolvidos computacionais na linguagem Fortran Power Station, e efetuadas várias simulações de diferentes parâmetros de antenas, com o objetivo de diminuir as dimensões físicas e aumentar a largura de banda das mesmas, incluindo frequências de Terahertz (nanotecnologia).

    É apresentada uma análise teórica e numérica usando o método LTT para linha de lâmina as acopladas com substrato EBG/PBG, com aplicações nas frequências de ondas milimétricas.

    Também são incluídos nesta tese pesquisas e simulações usando software HFSS sobre filtros pseudo-interdigital, filtros de Harpin e diplexer que servem como base teórico-experimental, para o desenvolvimento de uma nova estrutura chamada “filtro-antena integrada”.

    Os resultados são apresentados através de gráficos em 2D e 3D (3 dimensões). A análise teórico-computacional desse trabalho se mostra precisa e concisa. São apresentadas as conclusões e sugestões para trabalhos futuros.

5
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • ESTUDO DO ACOPLAMENTO ENTRE SUPERFÍCIES SELETIVAS DE FREQUÊNCIA ASSIMÉTRICAS EM ESTRUTURAS DE MULTICAMADAS

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • Data: Jun 18, 2012


  • Show Abstract
  • Este trabalho apresenta o desenvolvimento de novas estruturas de micro-ondas, filtros e antena de alto ganho, através do cascateamento de superfícies seletivas em frequência, que usa patches retangulares e fractais de Koch triangular como elementos.

    Superfícies seletivas em frequência (FSS) abrangem uma grande área das Telecomunicações e têm sido largamente utilizadas devido a seu baixo custo, peso reduzido e possibilidade de se integrar com outros circuitos de micro-ondas. Elas são especialmente importantes em diversas aplicações, como aviões, sistemas de antenas, radomes, foguetes, mísseis, etc. Aplicações de FSS em faixas de frequência elevadas têm sido investigadas, assim como aplicações destas estruturas em cascata ou multicamadas, FSS ativas.

    Nesse trabalho, são apresentados resultados simulados e medidos para as características de transmissão de estruturas cascateadas (multicamadas), com intuito de investigar o comportamento do funcionamento em termos de largura de banda, um dos grandes problemas apresentados por superfícies seletivas em frequência.

    São feitas comparações entre resultados simulados, obtidos utilizando software comercial como Ansoft DesignerTM v3 e resultados medidos em laboratório.

    São apresentadas, ainda, sugestões de continuidade do trabalho.

6
  • ANDERSON ABNER DE SANTANA SOUZA
  • Mapeamento Robótico 2,5-D com Representação em Grade de Ocupação-Elevação

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDRE MACEDO SANTANA
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • FLAVIO TONIDANDEL
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Aug 3, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Este trabalho apresenta um novo métodoo de mapeamento de ambientes com robôs móveis com informações tridimensionais para navegação. Muitas abordagens de mapeamento 3D, usam o método em grade de ocupação, o que resulta no uso de muito recurso computacional tanto na construção como no armazenamento desses mapas. A presente pesquisa apresenta o mapeamento 2,5-D em grade de ocupação-elevação, a qual é definida como uma representação discreta, onde cada célula armazena uma probabilidade de ocupação, a altura do espaço mapeado e a variância desse valor de altura. Essa representação permite que um robô móvel tenha a ciência se um lugar do seu ambiente está ocupado por um obstáculo e qual a altura desse obstáculo. Dessa forma, ele pode decidir se é possível navegar sobre o obstáculo ou não, de acordo com suas habilidades motoras. As informações sensoriais necessárias para construir o mapa são providas por um sistema de visão estéreo, o qual foi modelado através de uma robusta análise estatística, considerando os ruídos presentes no processamento estéreo. Os mapas resultantes favorecem a execução de tarefas como tomadas de decisões na navegação autônoma, exploração, localização e planejamento de caminhos. Experimentos práticos reais motram que o método de mapeamento apresentado é útil para a navegação de robôs autônomos.

7
  • JOSÉ MARCELO LIMA DUARTE
  • Algoritmos e Arquiteturas VLSI para Detectores MIMO com Decisão Suave

  • Advisor : JOSE ALBERTO NICOLAU DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • JORGE DANTAS DE MELO
  • MARCELO AUGUSTO COSTA FERNANDES
  • DAVID SIMONETTI BARBALHO
  • LUIZ GONZAGA DE QUEIROZ SILVEIRA JUNIOR
  • DALTON SOARES ARANTES
  • MANOEL EUSEBIO DE LIMA
  • Data: Aug 17, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • O uso de sistemas de Múltiplas Entradas e Múltiplas Saídas (Multiple Input Multiple Output - MIMO) tem permitido a recente evolução dos novos padrões de comunicação móvel. A técnica MIMO da Multiplexação Espacial, em particular, provê um aumento linear na capacidade de transmissão com o mínimo entre número de antenas transmissoras e antenas receptoras. Para se obter um desempenho próximo a capacidade em sistemas com Multiplexação Espacial faz-se necessário o uso de um detector MIMO com decisão suave do tipo Maximum a Posteriori Probability. Entretanto, tal detector é muito complexo para soluções práticas. Assim, o objetivo dos algoritmos de detecção MIMO voltados para implementação é obter uma boa aproximação do detector ideal mantendo um nível de complexidade aceitável. Além disso, o algoritmo precisa ser mapeado para uma arquitetura VLSI de área pequena e que atenda a taxa de transmissão exigida pelos padrões de comunicações móveis. Sendo a multiplexação espacial uma técnica recente, defende-se que ainda há muito espaço para evolução dos algoritmos e arquiteturas relacionadas. Por isso, esta tese se focou no estudo de algoritmos e arquiteturas VLSI para detectores MIMO de banda larga com decisão suave. Como resultado, algoritmos inéditos foram desenvolvidos partindo de propostas de otimizações para algoritmos já estabelecidos. Baseado nesses resultados, novas arquitetura de detectores MIMO com modulação configurável e competitivos parâmetros de área, desempenho e taxa de processamento foram propostas. Os algoritmos desenvolvidos foram extensivamente simulados e as arquiteturas sintetizadas para que os resultados pudessem servir como referência para outros trabalhos na área.

8
  • ALBERTO SIGNORETTI
  • Agentes Inteligentes com Foco de Atenção Afetivo em Simulações Baseadas em Agentes

  • Advisor : SERGIO VIANNA FIALHO
  • COMMITTEE MEMBERS :
  • ANDRE MAURICIO CUNHA CAMPOS
  • ANNE MAGALY DE PAULA CANUTO
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • GEBER LISBOA RAMALHO
  • LUIZ CHAIMOWICZ
  • SERGIO VIANNA FIALHO
  • Data: Aug 17, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Simulações baseadas em agentes cognitivos podem se tornar tarefas computacionalmente intensivas, especialmente quando o ambiente de simulação é um sistema complexo, formado por muitas variáveis. Este panorama se torna pior à medida em que restrições de tempo são adotadas. Simulações desse tipo seriam beneficiadas por um mecanismo que melhorasse o modo pelo qual os agentes percebem e reagem a mudanças nesses tipos de ambiente. Ou seja, uma abordagem para melhorar a eficiência (desempenho e acurácia) no processo de decisão de agentes autônomos em uma simulação, seria útil.

    Em ambientes complexos e repletos de variáveis, é possível que nem todas as informações disponíveis para o agente sejam realmente necessárias para o seu processo de decisão, dependendo, é claro, da tarefa que esteja sendo executada. Com a utilização de um foco de atenção, somente as informações importantes ao contexto de execução do agente percebidas, o que melhoraria o processo de decisão. Esse processo se tornaria mais rápido e também mais acurado, pois estariam sendo usadas somente as informações realmente necessárias.

    A arquitetura proposta neste trabalho apresenta uma estrutura de agentes cognitivos dividida em duas partes: uma parte principal contendo o raciocínio/planejamento, o conhecimento e o estado afetivo do agente e um conjunto de comportamentos que serão acionados pelo planejamento com o intuito de atingir os objetivos do agente. Cada um desses comportamentos possui um foco de atenção ajustável dinamicamente durante o tempo de execução do agente, de acordo com a variação do seu estado afetivo.

    O foco de atenção presente em cada comportamento é dividido em foco espacial, o qual é responsável pela qualidade dos dados percebidos, e no foco temporal, o qual é responsável pela quantidade dos dados percebidos. Desse modo, o comportamento será capaz de filtrar as informações enviadas pelos sensores do agentes e construir uma lista de elementos contendo somente as informações necessária ao agente dependendo do contexto do comportamento em execução no momento.

    O estado afetivo do agente é baseado nas teorias humanas da emoções, humor e personalidade. Esse modelo atua como base para o mecanismo de ajuste contínuo do foco de atenção do agente, tanto da parte espacial, como da parte temporal. Com esse mecanismo, o agente pode ajustar o seu foco de atenção durante a execução do comportamento de forma a tornar-se mais eficiente perante as mudanças ocorridas no ambiente.

    A arquitetura proposta pode ser utilizada de forma bastante flexível. O foco de atenção pode trabalhar de forma fixa, onde nem o espacial e nem o temporal variam, como também com as combinações possíveis entre a variação ou não dos focos espacial e temporal. A arquitetura foi desenvolvida sobre uma plataforma para agentes BDI, mas o seu projeto permite que seja usada em qualquer outro tipo de agente, pois as alterações são feitas apenas no nível da percepção do agente.

    Uma série extensa de experimentos, onde os agentes utilizando a arquitetura proposta neste trabalho são comparados com agentes oniscientes, comprovaram a efetividade dessa arquitetura.

9
  • CLAUDILENE GOMES DA COSTA
  • Probabilidades Imprecisas: Intervalar, Fuzzy e Fuzzy Intuicionista

  • Advisor : BENJAMIN RENE CALLEJAS BEDREGAL
  • COMMITTEE MEMBERS :
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • ADRIAO DUARTE DORIA NETO
  • GRAÇALIZ PEREIRA DIMURO
  • RONEI MARCOS DE MORAES
  • Data: Aug 20, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A idéia de considerar imprecisão em probabilidades é antiga, remontando aos trabalhos de George Booles, que em 1854 pretendia conciliar a lógica clássica, que permite modelar ignorância completa, com probabilidades. Em 1921, John Maynard Keynes em seu livro fez uso explícito de intervalos para representar a imprecisão nas probabilidades. Porém, apenas a partir dos trabalhos de Walley em 1991 que foram estabelecidos princípios que deveriam ser respeitados por uma teoria de probabilidades que lide com imprecisões.


    Com o surgimento da teoria dos conjuntos fuzzy em 1965 por Lotfi Zadeh, surge uma outra forma de lidar com incertezas e imprecisões de conceitos. Rapidamente, começaram a se propor diversas formas de considerar as idéias de Zadeh em probabilidades, para lidar com imprecisões, seja nos eventos associados às probabilidades como aos valores das probabilidades.

    Em particular, James Buckley, a partir de 2003 começa a desenvolver uma teoria de probabilidade fuzzy em que os valores das probabilidades sejam números fuzzy. Esta probabilidade fuzzy segue  princípios análogos ao das probabilidades imprecisas de Walley.

    Por outro lado, usar como graus de verdade números reais entre 0 e 1, como proposto originalmente por Zadeh, tem o inconveniente de usar valores muito precisos para lidar com incertezas (como alguém pode diferenciar de forma justa que um elemento satisfaz uma propriedade com um grau 0.423 de algo que satisfaz com grau 0.424?). Isto motivou o surgimento de diversas extensões da teoria dos conjuntos fuzzy pelo fato de incorporar algum tipo de imprecisão.

    Neste trabalho é considerada a extensão proposta por Krassimir Atanassov em 1983, que adicionou um grau extra de incerteza para modelar a hesitação ao momento de se atribuir o grau de pertinência, e portanto, um valor indicaria o grau com o qual o objeto pertence ao conjunto, enquanto o outro, o grau com o qual não pertence. Na teoria dos conjuntos fuzzy de Zadeh, esse grau de não-pertinência  por defeito é o complemento do grau de pertinência. Assim, nessa abordagem o grau de não-pertinência é de alguma forma independente do grau de pertinência, e nessa diferencia entre essa não-pertinência e o complemento do grau de pertinência revela a hesitação presente ao momento de se atribuir o grau de pertinência. Esta nova extensão hoje em dia é chamada de teoria dos conjuntos fuzzy intuicionistas de Atanassov. Vale salientar, que o termo intuicionista aqui não tem relação com o termo intuicionista como conhecido no contexto de lógica intuicionista.

    Será apresentado neste trabalho duas propostas de probabilidade intervalar: a probabilidade intervalar restrita e a probabilidade intervalar irrestrita; também serão introduzidas duas noções de probabilidade fuzzy: a probabilidade fuzzy restrita e a probabilidade fuzzy irrestrita e por fim serão introduzidas duas noções de probabilidade fuzzy intuicionista: a probabilidade fuzzy intuicionista restrita e a probabilidade fuzzy intuicionista irrestrita.

10
  • JOSE LUIZ DA SILVA JUNIOR
  • Determinação de chaveamentos para recomposição do serviço em redes de distribuição de energia elétrica em média tensão através de método baseado em parâmetros de sensibilidade.

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • ARRHENIUS VINICIUS DA COSTA OLIVEIRA
  • JOÃO PAULO ABREU VIEIRA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Sep 14, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • A reconfiguração de uma rede de distribuição é uma modificação na sua topologia, objetivando o atendimento de determinadas condições operativas dessa rede, através da mudança de estado das suas chaves (NA/NF). Ela pode ser realizada sem que qualquer anomalia tenha ocorrido no sistema. A recomposição de serviço é um caso particular da reconfiguração e deverá ser realizada sempre que ocorrer defeito na rede ou sempre que um ou mais trechos de um alimentador tenham sido retirados de serviço para manutenção. Nesses casos, cargas que são atendidas por trechos que estão a jusante de trechos retirados para manutenção, poderão ser atendidas pelo fechamento de chaves pertencentes ao mesmo alimentador sob manutenção ou através de chaves para outros alimentadores. Pelos métodos de reconfiguração clássicos, vários chaveamentos poderão ser necessários além daqueles utilizados apenas para realizar a recomposição do serviço.  Isso inclui chaveamentos em alimentadores da mesma subestação ou de outras subestações que não guardam qualquer relação direta com o alimentador sob defeito. Esses últimos chaveamentos provocarão  desconforto, prejuízos e insatisfação nos consumidores, além de prejuízos para a imagem da concessionária de energia elétrica. É objetivo desta tese de doutorado desenvolver uma heurística para reconfiguração de uma rede de distribuição, quando da ocorrência de um defeito nessa rede, realizando chaveamentos apenas nos alimentadores diretamente envolvidos nesse defeito, considerando que esses chaveamentos são aqueles destinados exclusivamente à isolação das barras e trechos defeituosos e ao atendimento das ilhas por ele geradas, com redução significativa do número de aplicações de fluxos de cargas aplicados, em função da utilização de parâmetros de sensibilidade para a determinação de tensões e correntes estimadas nas barras e trechos dos alimentadores envolvidos. Uma comparação desse processo com os métodos clássicos é realizada para várias redes testes obtidas na literatura sobre reconfiguração de redes.

11
  • TIAGO MARITAN UGULINO DE ARAUJO
  • Uma Solução para Geração Automática de Trilhas em Língua Brasileira de Sinais em Conteúdos Multimídia

  • Advisor : GUIDO LEMOS DE SOUZA FILHO
  • COMMITTEE MEMBERS :
  • CELSO ALBERTO SAIBEL SANTOS
  • GUIDO LEMOS DE SOUZA FILHO
  • LUIZ FERNANDO GOMES SOARES
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Sep 14, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Os surdos enfrentam sérias dificuldades para acessar informações. As Tecnologias de
    Informação e Comunicação (TIC) quando são desenvolvidas dificilmente levam em consideração os requisitos específicos destes usuários especiais. O suporte para línguas de
    sinais, por exemplo, é raramente explorado nessas tecnologias. Além disso, as soluções
    presentes na literatura relacionadas a tradução automática para línguas de sinais são restritas a um domínio de aplicação específico ou não são viáveis para cenários que necessitam
    de tradução em tempo real, como, por exemplo, na TV. Para reduzir esses problemas,
    neste trabalho é proposta uma solução para geração automática de trilhas em Língua Brasileira de Sinais (LIBRAS) em conteúdos digitais multimídia. As trilhas de LIBRAS são
    geradas a partir de uma estratégia de tradução automática e em tempo real para LIBRAS,
    que realiza a tradução a partir de fluxos de legendas (como, por exemplo, legendas ou
    closed caption) em língua portuguesa. Além disso, a solução proposta é de domínio geral
    e dotada de um conjunto de mecanismos que exploram a colaboração e a computação
    humana para gerar e manter suas construções lingüísticas de forma eficiente. Implementações da solução proposta foram desenvolvidas para as plataformas de TV Digital, Web
    e Cinema Digital, e um conjunto de experimentos, incluindo testes com usuários surdos,
    foi desenvolvido para avaliar os principais aspectos da solução. Os resultados mostraram
    que a solução proposta é eficiente, capaz de gerar e embarcar as trilhas de LIBRAS em
    cenários que exigem tradução em tempo real, além de ser uma alternativa prática e viá-
    vel para redução das barreiras de acesso à informação dos surdos, especialmente quando
    intérpretes humanos não estão disponíveis.

12
  • SAMUEL OLIVEIRA DE AZEVEDO
  • Arquitetura para Aplicações Interativas Imersivas de Televisão Digital

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANDERSON ABNER DE SANTANA SOUZA
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • SERGIO QUEIROZ DE MEDEIROS
  • Data: Sep 24, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Neste trabalho, propomos uma nova abordagem para a Televisão Digital Interativa
    (TVDI), visando explorar os conceitos de imersividade. Várias arquiteturas já foram propostas
    para a TVDI, mas não exploram coerentemente quesitos relacionados à imersão.
    O problema tratado nesta proposta consiste em definir formalmente o que são a imersão
    e a interatividade para a TV digital e em como elas podem ser usadas para melhorar
    a experiência do usuário deste novo modelo televisivo. A abordagem do problema levanta
    questões como a escolha apropriada de equipamentos para ajudar na sensação de
    imersão; que formas de interação entre os usuários podem ser exploradas no contexto
    interação-imersão; se o ambiente em que uma aplicação interativa imersiva é utilizada
    influencia na experiência de imersão; e que novas formas de interatividade dos usuários
    da TVDI entre si, e entre os usuários e as aplicações interativas, podem ser exploradas
    com o uso da imersão. Como um dos objetivos desta proposta, apontamos soluções novas
    para estas questões que carecem de mais estudos. Ensejamos formalizar os conceitos que
    abarcam a interatividade no Sistema Brasileiro de televisão Digital. Num estudo inicial
    realizado, esta definição é organizada em categorias ou níveis de interatividade. A partir
    deste ponto, são feitas análises e especificações para atingir a imersão usando a TVDI.
    Visionamos alguns estudos de caso de aplicações interativas imersivas para televisão digital,
    visando validar a arquitetura proposta. Também, é abordado o uso de dispositivos
    remotos, e a proposta básica de uma arquitetura de middleware que permita sua utilização
    em conjunto com aplicações interativas imersivas.

13
  • ADRIANA TAKAHASHI
  • Máquina de Vetores-Suporte Intervalar

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • JORGE DANTAS DE MELO
  • AARAO LYRA
  • RENATA HAX SANDER REISER
  • TIAGO ALESSANDRO ESPÍNOLA FERREIRA
  • Data: Sep 26, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • As máquinas de vetores suporte (SVM - Support Vector Machines) têm atraído muita
    atenção na área de aprendizagem de máquinas, em especial em classificação e reconhecimento
    de padrões, porém, em alguns casos nem sempre é fácil classificar com precisão
    determinados padrões entre classes distintas. Este trabalho envolve a construção de um
    classificador de padrões intervalar, utilizando a SVM associada com a teoria intervalar,
    de modo a modelar com uma precisão controlada a separação entre classes distintas de
    um conjunto de padrões, com o objetivo de obter uma separação otimizada tratando de
    imprecisões contidas nas informações do conjunto de padrões, sejam nos dados iniciais
    ou erros computacionais.
    A SVM é uma máquina linear, e para que ela possa resolver problemas do mundo
    real, geralmente problemas não lineares, é necessário tratar o conjunto de padrões, mais
    conhecido como conjunto de entrada, de natureza não linear para um problema linear,
    as máquinas kernels são responsáveis por esse mapeamento. Para a extensão intervalar
    da SVM, tanto para problemas lineares quanto não lineares, foi preciso a definição de
    kernel intervalar, bem como o teorema que valida uma função ser um kernel, o teorema
    de Mercer para funções intervalares.

14
  • HERTZ WILTON DE CASTRO LINS
  • Análise e Síntese de Antenas e Superfícies Seletivas de Frequência Utilizando Computação Evolucionária e Inteligência de Enxames

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LAERCIO MARTINS DE MENDONCA
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • Data: Oct 11, 2012


  • Show Abstract
  • As superfícies seletivas de frequência do inglês Frequency Selective Surfaces (FSS), são
    dispositivos utilizados em alta frequência caracterizados por terem na sua composição
    condutores metálicos conhecidos como patches, consistindo de uma disposição periódica
    de elementos. Estas estruturas têm sido utilizadas em aeronaves, satélites, mísseis
    teleguiados e sistemas de antenas refletoras em aplicações como, por exemplo, seleção
    de banda de frequência de operação e filtragem de frequências. Sistemas e tecnologias de
    comunicação modernas, como o GSM (sistema global para comunicações móveis),
    RFID (Radio Frequency Identification), Bluetooth, Wi-Fi e WiMAX, exigem antenas
    com um conjunto de requisitos como: baixo custo, perfil, peso reduzido e pequeno
    tamanho. A antena de microfita representa uma solução possível para atender a esses
    requisitos, alem disso sua versatilidade é observada em aspectos como a capacidade para
    integrar-se com o resto do circuito impresso, a simplicidade na construção e robustez. A
    análise e a síntese destes dispositivos, principalmente a síntese, em face da grande
    possibilidade de formas, dimensões e periodicidade de seus elementos exige uma análise
    numérica complexa, usando: método dos elementos finitos, método dos momentos,
    método das diferenças finitas no domínio do tempo. Neste contexto a inteligência
    computacional tem sido aplicada com sucesso no desenvolvimento e otimização destas
    estruturas. A inteligência computacional é inspirada em fenômenos naturais como:
    aprendizado, percepção e decisão, utilizando técnicas como redes neurais artificiais,
    lógica fuzzy, geometria fractal e computação evolucionária, em diversas áreas da
    engenharia e tecnologia, com o objetivo de resolver problemas complexos em situações
    em que métodos convencionais não são eficientes. Este trabalho realiza um estudo de
    aplicação de inteligência computacional utilizando meta-heuristicas como algoritmos
    genéticos e inteligência de enxames na otimização de antenas e superfícies seletivas de
    frequência. Os algoritmos genéticos são métodos computacionais de busca baseados na
    teoria da seleção natural proposta por Darwin e na genética utilizada para resolver
    problemas complexos como, por exemplo, problemas em que o espaço de busca cresce
    com as dimensões do problema, a otimização por enxame de partículas tem como
    características a utilização da inteligência de forma coletiva sendo aplicada em
    problemas de otimização em diversas áreas de pesquisa. Estas são eficientes quando
    aplicadas nestes dispositivos, a eficiência destas técnicas foi comprovada através de
    resultados simulados e experimentais.

15
  • VALCI FERREIRA VICTOR
  • Viabilidade da Utilização de Máquinas de Indução Convencionais como Motores sem Mancais Mecânicos

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • JOSE ALVARO DE PAIVA
  • JOSSANA MARIA DE SOUZA FERREIRA
  • RICHARD MAGDALENA STEPHAN
  • Data: Nov 5, 2012


  • Show Abstract
  • Este trabalho descreve o estudo e a implementação uma máquina de indução convencional funcionando como uma máquina sem mancais trifásica com bobinado dividido. Utilizando uma maquina convencional  de 4 pólos e 3.7kW. Os controles de velocidade, posicionamento radial e das correntes do estator operam simultaneamente em cada fase do estator. Para o posicionamento radial utilizam-se as forças controladas pelos campos magnéticos no interior da máquina. Todo o controle do sistema é realizado por um programa desenvolvido em linguagem padrão ANSI C. Os recursos do DSP utilizados pelo sistema são: os canais de conversão A/D, as saídas PWM e as interfaces paralela e serial RS-232, as quais são responsáveis, respectivamente, pela programação do DSP e a captura de dados através de um sistema de supervisão. A originalidade do trabalho está é a utilização de um motor de indução trifásico convencional de fácil aquisição sem adaptações no rotor ou estator como máquina sem mancais.

16
  • ROBINSON LUIS DE SOUZA ALVES
  • Uma contribuição ao estudo das categorias internas e de sua proliferação em redes ARTMAP

  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • JORGE DANTAS DE MELO
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • ALUIZIO FAUSTO RIBEIRO ARAÚJO
  • ROGERIO ANDRADE FLAUZINO
  • Data: Nov 5, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • As redes do tipo ART apresentam grandes vantagens, porém alguns problemas existem. O mais importante deles é o problema da proliferação de categorias e é provavelmente o mais crítico. Esse problema faz com que a rede crie várias categorias consumindo recursos (recursos de uso para armazenar uma grande quantidade de categorias impactando negativamente ou até mesmo inviabilizando o tempo de processamento da rede) sem contribuir para a qualidade da representação do problema. Ou seja, em muitos casos a quantidade excessiva de categorias geradas pelas redes ART faz com que a qualidade da generalização da rede seja inferior ao que deveria ser. Outro problema das redes do tipo ART é a dificuldade de aproximar regiões que tem geometria não retangular, ocasionando uma generalização inferior a outros métodos de classificação. A partir da observação desses problemas, foi desenvolvido esse trabalho que utiliza uma geometria mais flexível do que a geometria fixa presente nas redes ART tradicionais. Assim, propõe-se nesse trabalho a utilização de politopos convexos para representar a geometria de cada categoria da rede neural.

17
  • RAFAEL VIDAL AROCA
  • Plataforma robótica de baixíssimo custo para robótica educacional

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • FLAVIO TONIDANDEL
  • GLAUCO AUGUSTO DE PAULA CAURIN
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Dec 17, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Os robôs estão cada vez mais presentes na sociedade, porém ainda são considerados equipamentos caros e restritos para poucas pessoas. Este trabalho consiste no desenvolvimento de uma técnica e arquitetura de controle que possibilita a construção de robôs de baixo custo e com baixa complexidade de construção e programação. Um aspecto chave da arquitetura proposta, é o uso de uma interface de áudio para controlar atuadores e ler sensores, permitindo assim o uso de qualquer dispositivo que produza sons como unidade de controle do robô. Também foram desenvolvidas ferramentas de programação baseadas na web, permitindo o uso de computadores ou telefones celulares como unidade de controle do robô. O trabalho também contempla possíveis aplicações de tal plataforma robótica de baixo custo, incluindo uma pesquisa de opinião realizada com alunos de graduação.

18
  • ROSIERY DA SILVA MAIA
  • Modelo de Desenvolvimento Intelectual para Agentes Robóticos

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • DANIEL ALOISE
  • ANDERSON ABNER DE SANTANA SOUZA
  • SILVIA SILVA DA COSTA BOTELHO
  • Data: Dec 18, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • IDeM-MRS é um formalismo de cooperação para um grupo de robôs heterogêneos eficientemente resolver tarefas em um determinado ambiente fechado. Esse formalismo é totalmente baseado em modelos sociais de aprendizagem de indivíduos reais e coordena o grupo propiciando a assimilação e acomodação do conhecimento através de trocas de experiências. Algumas questões foram particulamente tratadas, como uma representação realista do ambiente multirrobô (que envolve a missão global, as tarefas que pertencem a essa missão e os robôs atuantes) e uma forma de seleção de tarefas, baseada em teorias e abordagens socias de aprendizagem, que permitem a execução cooperativa e eficiente pelos robôs. IDeM-MRS pode ser usado em diferentes tipos de missões, desde as mais simples às mais complexas. Os experimentos e resultados validam a eficiência desse formalismo em comparação a um modelo empírico tradicional.

19
  • CARLOS ANDRE GUERRA FONSECA
  • Estrutura ANFIS Modificada para Identificação e Controle de Plantas com Ampla Faixa de Operação e não Linearidade Acentuada

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • DANIELLE SIMONE DA SILVA CASILLO
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • TAKASHI YONEYAMA
  • Data: Dec 21, 2012
  • View Dissertation/Thesis  

  • Show Abstract
  • Neste trabalho propõe-se uma modificação na estrutura neurofuzzy ANFIS (Adaptive Network Based Fuzzy Inference System) para a obtenção de um método sistemático para identificação e controle de plantas com ampla faixa de operação e não linearidade acentuada, a partir de técnicas lineares de identificação e controle. Este método se baseia na metodologia de múltiplos modelos. Dessa forma, obtêm-se modelos lineares locais e esses são combinados pela estrutura neurofuzzy proposta. Uma métrica que permite combinar adequadamente esses modelos é obtida após o treinamento dessa estrutura, resultando na identificação global da planta. Para cada um desses modelos é projetado um controlador. O controle global é obtido a partir da mistura dos sinais dos controladores locais. Essa mistura é feita pelo ANFIS modificado. A modificação na arquitetura do ANFIS permite o compartilhamento do conhecimento adquirido pelo treinamento da estrutura empregada na combinação de modelos locais. Assim não se faz necessário o treinamento da estrutura empregada na mistura de controladores. Validaram-se as estruturas modificadas através de dois estudos de caso. Verificou-se que é possível treinar apenas um ANFIS, para a obtenção de uma métrica que permita a combinação adequada dos modelos lineares, válidos localmente, e essa estrutura, já ajustada, pode ser aplicada na combinação de controladores lineares, projetados para cada um dos modelos, resultando em um sistema de controle que satisfaz as especificações de desempenho previamente estabelecidas. O método proposto possibilita a utilização de quaisquer técnicas de identificação e controle para a obtenção dos modelos e controladores locais, e a redução da complexidade de utilização do ANFIS para identificação e controle. Neste trabalho priorizaram-se as técnicas mais simples de identificação e controle de sistemas de forma a simplificar a utilização do método.

2011
Dissertations
1
  • BRUNO JÁCOME CAVALCANTI
  • SISTEMA WEB DIDÁTICO PARA A SUPERVISÃO DE REDES FIELDBUS

  • Advisor : CLAUDIO RODRIGUES MUNIZ DA SILVA
  • COMMITTEE MEMBERS :
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • RONALDO DE ANDRADE MARTINS
  • ROSSANA MORENO SANTA CRUZ
  • Data: Jan 31, 2011


  • Show Abstract
  • A evolução tecnológica dos sistemas de automação industrial tem sido norteada pelo dilema entre flexibilização e confiabilidade na integração entre equipamentos e sistemas supervisórios de controle. No entanto, são poucos os sistemas supervisórios cujas atribuições também abrangem o ensino do processo de comunicação que ocorre por trás dessa integração tecnológica, sendo os existentes pouco flexíveis no que se refere ao acesso e à abrangência de padrões. Este trabalho apresenta um sistema supervisório didático, acessível via web, que é utilizado no ensino dos principais protocolos Fieldbus. O aplicativo proposto possui um módulo de descoberta automática da topologia da rede usada e permite que alunos e/ou profissionais da área de automação obtenham um conhecimento mais prático desses protocolos ao auxiliar na construção e envio de quadros próprios da rede Fieldbus considerada, propiciando aos envolvidos um conhecimento mais detalhado do processo de comunicação que ocorre entre um sistema supervisório de automação e os dispositivos escravos utilizados na rede. Pelo fato de ser uma aplicação web, além de contemplar o modo de ensino presencial, o sistema proposto permite o acesso remoto ao CLP, comportando um número bem maior de usuários e tornando mais abrangente seu universo de aplicação. Este primeiro módulo é voltado para o protocolo Modbus (abrangendo suas variações TCP e Serial RTU/ASCII).

2
  • RAPHAELL MACIEL DE SOUSA
  • Estratégia de Controle Robusto para Filtro Ativo Paralelo sem Detecção de Harmônicos de Correntes
  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • FABIANO FRAGOSO COSTA
  • MAURICIO AREDES
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Feb 11, 2011


  • Show Abstract
  • As estratégias de controle convencionais de filtros ativos de potência paralelos empregam esquemas de detecção de harmônicos em tempo real, usualmente implementados com filtros digitais. Isso aumenta o número de sensores na estrutura do filtro, o que resulta em altos custos. Além disso, esses esquemas de detecção introduzem atrasos que podem deteriorar o desempenho da compensação de harmônicos. Diferentemente dos esquemas de controle convencionais, este trabalho pretende desenvolver estudos, para proposição de estratégias de controle, que regulem indiretamente as correntes de fase da rede elétrica e que possuam mecanismos de adaptação, para compensação de eventuais variações paramétricas da rede ou da carga.

3
  • DANIEL LOPES MARTINS
  • Arquitetura de controladores Fuzzy em Redes Foundation Fieldbus

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DENNIS BRANDAO
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Feb 14, 2011


  • Show Abstract
  • Com o avanço da tecnologia da informação e do poder de processamento dos dispositivos, torna-se possível utilizar novas aplicações cada vez mais rápidas, eficientes e seguras no ambiente industrial. Isso permite o aumento da produtividade com cada vez menos desperdício de mão de obra e de matéria prima, o que acarreta no aumento da lucratividade e da produção. Essas aplicações vão desde compensar medições de variáveis não-lineares utilizando tabelas na memória dos dispositivos até controladores para complexos processos. Um desses tipos de controlador é o controlador Fuzzy. A lógica Fuzzy permite que as máquinas possam entender linguagens vagas e imprecisas, como é o caso da linguagem humana, podendo tomar decisões baseadas nelas. Este tipo de controlador é normalmente implementado em dispositivos com grande capacidade de processamento (como CLPs) devido a existência de alguns cálculos complexos que nem sempre podem ser realizados por dispositivos de campo (sensores e atuadores inteligentes). A motivação para a realização deste trabalho surgiu justamente desta ausência de um controlador Fuzzy dentro do ambiente das redes industriais, mais especificamente das redes Foundation Fieldbus. Os principais desafios na construção deste tipo de controlador são as próprias limitações que os blocos funcionais deste tipo de rede impõem, impedindo de realizar determinados tipos de cálculos, e a configuração do controlador, exigindo a implementação de um software que auxiliasse a configuração do controlador dentro da rede Foundation Fieldbus. O controlador desenvolvido foi utilizado no controle do nível de água em
    um sistema de tanques e os resultados obtidos foram comparados com os resultados obtidos no controle do mesmo sistema através de um controlador Fuzzy de um software matemático, o que mostra que o controlador implementado na rede, apesar de suas limitações, pode alcançar resultados tão bons quanto os resultados de controladores em sistemas de maior poder de processamento.

4
  • JOSÉ SOARES BATISTA LOPES
  • Controle Preditivo Robusto baseado em Desigualdades Matriciais Lineares aplicado a um Sistema de Tanques Acoplados

  • Advisor : ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • OSCAR GABRIEL FILHO
  • Data: Feb 14, 2011


  • Show Abstract
  • Este trabalho tem como objetivo desenvolver uma estratégia de controle on-line baseado no Controlador Preditivo Robusto (RMPC, acrônimo do inglês Robust Model Predictive Control) aplicado a um sistema real de tanques acoplados. Este processo consiste em um sistema de dois tanques conectados cujo liquido é enviado, aos mesmos, por uma bomba. Os níveis dos tanques, em centímetros, são transmitidos para um Controlador Lógico Programável (CLP) através de um sinal de tensão, com fator de escala 1V/6,25cm. Já o sinal de controle, em volts, gerado no CLP, é transmitido para a bomba amplificado em cinco vezes. A síntese da técnica RMPC consiste em incorporar de forma explicita as incertezas da planta na formulação do problema. O objetivo do projeto, a cada período de amostragem, é encontrar uma realimentação de estados que minimiza o pior caso de uma função objetivo  com horizonte infinito, sujeita as restrições no sinal de controle. O problema original, do tipo Min-max, é reduzido em um problema de otimização convexa expresso em desigualdades lineares matriciais (LMI, acrônimo do inglês Linear Matriz Inequalities). Mostra-se, nesse trabalho, a descrição da incerteza da planta na forma politopica e as  condições de factibilidade do projeto de controle. A implementação do algoritmo RMPC foi feita utilizando o Scilab e a sua comunicação com o sistema de tanques acoplados foi através do protocolo OPC (do inglês OLE for Process Control).

5
  • BRUNO MARQUES FERREIRA DA SILVA
  • Odometria Visual Baseada em Técnicas de "Structure from Motion"

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • DENNIS BARRIOS ARANIBAR
  • LUIZ MARCOS GARCIA GONCALVES
  • RICARDO CORDEIRO DE FARIAS
  • RUMMENIGGE RUDSON DANTAS
  • Data: Feb 17, 2011


  • Show Abstract
  • Odometria Visual é o processo pelo qual consegue-se obter a posição e orientação de uma câmera, baseado somente em imagens e consequentemente, em características (projeções de marcos visuais da cena) nelas contidas. Com o avanço nos algoritmos e no poder de processamento dos computadores, a subárea de Visão Computacional denominada de Structure from Motion (SFM) passou a fornecer ferramentas que compõem sistemas de localização visando aplicações como robótica e Realidade Aumentada, em contraste com o seu propósito inicial de ser usada em aplicações predominantemente offline como reconstrução 3D e modelagem baseada em imagens. Sendo assim, este trabalho propõe um pipeline de obtenção de posição relativa que tem como características fazer uso de uma única câmera calibrada como sensor posicional e ser baseado interamente nos modelos e algoritmos de SFM. Técnicas usualmente empregadas em sistemas de localização de câmera como filtros de Kalman e filtros de partículas não são empregadas, dispensando que informações adicionais como um modelo probabilístico de transição de estados para a câmera sejam necessárias. Experimentos foram realizados com o propósito de avaliar tanto a reconstrução 3D quanto a posição de câmera retornada pelo sistema, através de sequências de imagens capturadas em ambientes reais de operação e comparações com um ground truth fornecido pelos dados do odômetro de uma plataforma robótica.

6
  • KEYLLY EYGLYS ARAÚJO DOS SANTOS
  • Um método para Localização Facial Invariante a Rotação

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ALLAN DE MEDEIROS MARTINS
  • MÁRIO SARCINELLI FILHO
  • Data: Feb 18, 2011


  • Show Abstract
  • A localização facial tornou-se um assunto muito discutido nos últimos anos, surgiram inúmeras aplicações, desde sistemas biométricos (que necessitam localizar a face antes de identifica-la), até sistemas complexos de varredura de multidões (procurando por criminosos). O método mais utilizado para localizar faces em imagens digitais é a técnica de Vioja e Jones, que não é invariante a rotação, conseguindo identificar apenas pequenos ângulos de rotação, mas ainda assim comprometendo alguns algoritmos que necessitam da face sem rotação, como a biometria facial.

    A técnica apresentada propõe a invariância a rotação da face, baseando-se na segmentação da pele para estimar o ângulo de rotação da face, realizando a rotação inversa para então entregar ao algoritmo de  Viola e Jones. Com isso, é possível obter a invariância a rotação além de estimar o ângulo de rotação da face.

7
  • RENATA PITTA BARROS
  • Evolução, Avaliação e Validação do Software Roboeduc

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • CARMEN RIBEIRO FARIA SANTOS
  • FRANCISCO MILTON MENDES NETO
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Feb 18, 2011


  • Show Abstract
  • Considerando a transição entre a Sociedade Industrial para a Sociedade da Informação, percebemos que a formação digital que é abordada atualmente é insuficiente para navegar no interior de uma realidade digitalizada. Como proposta para minimizar este problema este trabalho desenvolve um software, chamando RoboEduc, para trabalhar com programação de dispositivos robóticos em níveis, considerando as especificidades da realidade formativa, onde o quadro discente atual consiste por analfabetos, migrantes e nativos digitais. A ênfase deste trabalho está na apresentação dos procedimentos e materiais que envolvem o desenvolvimento deste software como também a realização de Testes de Usabilidade para uma análise dos resultados.

8
  • GIANNA RODRIGUES DE ARAUJO
  • Acelerando Algoritmos de Baixo Nivel em Visão Robótica com Hardware Reconfigurável

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • RAQUEL ESPERANZA PATIÑO ESCARCINA
  • RUMMENIGGE RUDSON DANTAS
  • Data: Feb 18, 2011


  • Show Abstract
  • Um desafio que ainda resta no campo da robótica é como fazer um robô reagir em tempo real a estímulos visuais. Técnicas tradicionais de visão robótica usadas para resolver este problema ainda são muito caras tomando muito tempo quando se usa processadores convencionais. Algoritmos simples com filtragem em imagens ou operações de morfologia matemática podem tomar muito tempo de execução. Pesquisadores têm implementado algoritmos de processamento de imagens em dispositivos de hardware com alto grau de paralelismo, visando diminuir o tempo de processamento nos algoritmos, com bons resultados. Usando técnicas de processamento de imagens implementadas em hardware e um sistema orientado a plataforma que usa o processador Nios II, propomos um método que usa processamento em hardware e programação baseada a eventos, para simplificar sistemas baseados em visão, enquanto que, ao mesmo tempo, conseguimos acelerar algumas partes dos algoritmos usados.

9
  • RAFAEL NUNES DE ALMEIDA PRADO
  • DESENVOLVIMENTO DE UMA ARQUITETURA EM HARDWARE PROTOTIPADA EM FPGA PARA APLICAÇÕES GENÉRICAS UTILIZANDO REDES NEURAIS ARTIFICIAIS EMBARCADAS

  • Advisor : JOSE ALBERTO NICOLAU DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DANNIEL CAVALCANTE LOPES
  • DAVID SIMONETTI BARBALHO
  • JORGE DANTAS DE MELO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • KARLA DARLENE NEPOMUCENO RAMOS
  • Data: Feb 22, 2011


  • Show Abstract
  • Propõe-se, neste trabalho, uma arquitetura em hardware, descrita em VHDL, desenvolvida para embarque de redes neurais artificiais, especificamente do tipo Multilayer Perceptron (MLP). Idealiza que nessa arquitetura, as aplicações com RNA tenham facilidade no procedimento de embarque de uma rede neural MLP em hardware, bem como de permitir facilidades na configuração de vários tipos de redes MLP em campo, com diferentes topologias (quantidade de neurônios e camadas). A definição da arquitetura MLP que o sistema proposto irá se configurar e executar depende de uma entrada de dados específica, a qual define a quantidade de neurônios, camadas e tipos de funções de ativação em cada neurônio. Para permitir essa maleabilidade de configurações nas RNA, um conjunto de componentes digitais (datapath) e um controlador foram necessários para executar instruções que definirão a arquitetura da rede MLP. Desta forma, o hardware funciona a partir de uma entrada de instruções previamente conhecidas por um usuário, as quais indicarão as características de uma determinada rede MLP, e o sistema irá garantir a execução da MLP desejada a partir dos processadores neurais desenvolvidos para o sistema, pelo controlador e pelos componentes do datapath. Separadamente, os pesos e bias terão de estar fixos, ou seja, a rede neural a ser embarcada já deve estar treinada de maneira off-line (realizada antecipadamente em software). O dispositivo reconfigurável FPGA foi escolhido para implementação, simulação e testes prototipados oportunizando aplicar o sistema a problemas reais do nosso cotidiano.

10
  • VITOR LOPES DOS SANTOS
  • Contribuições Para a Análise de Sinais Neuronais e Biomédicos

  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • GLAUCIO BEZERRA BRANDAO
  • MAURO COPELLI
  • SIDARTA TOLLENDAL GOMES RIBEIRO
  • Data: Mar 3, 2011


  • Show Abstract
  • Seguindo a nova tendência de interdisciplinaridade da ciência atual, a neuroengenharia vem crescendo nas últimas décadas. A partir do ano 2000, foram criados periódicos científicos e conferências em todo o mundo no tema. Esse trabalho envolve três subáreas da neuroengenharia relacionadas com engenharia elétrica e de computação: controle neural; neurociência teórica e computacional; e processamento de sinais neurais; assim como da engenharia biomédica.

    A pesquisa compreendeu três partes: (i) Uma técnica de fotoestimulação neural foi desenvolvida baseada no uso de compostos enjaulados. Usando o neurotransmissor inibitório GABA preso a um complexo de rutênio, foi possível provocar inibição quase instantânea da atividade cortical de camundongos com um pulso de laser. Os resultados foram obtidos por análise Wavelet de potenciais de campo e testados com estatística não-paramétrica. (ii) Um método matemático foi desenvolvido para identificação de assembléias neurais. Assembléias neurais foram primeiramente propostas por Donald Hebb (1949) como base do aprendizado, e atualmente constituem o modelo mais bem aceito para representação de informação no sistema nervoso. Usando a lei de Marcenko-Pastur da distribuição de autovalores de matrizes aleatórias foi possível detectar assembléias neurais, identificá-las e calcular a força de ativação com alta resolução temporal. Aplicação do método em dados eletrofisiológicos reais revelou neurônios do neocórtex e do hipocampo de ratos participam em uma mesma assembleia, e que neurônios podem participar em múltiplas assembleias. (iii) Um novo método de classificação automática de batimentos de eletrocardiograma foi desenvolvido, que não depende de um banco de dados para treinamento, e que não é especializado em patologias específicas. O método envolve decomposição Wavelet e medidas de normalidade de variáveis aleatórias.

    Em conjunto, os resultados obtidos nas três linhas de pesquisa representam capacitação em neuroengenharia e engenharia biomédica.

11
  • BRUNO XAVIER DA COSTA
  • Ambiente de Simulação Híbrido Integrando Hysys e Rede Industrial Foundation Fieldbus aplicado ao Controle de uma Coluna de Destilação

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • JORGE DANTAS DE MELO
  • LAERTE DE MEDEIROS BARROS JUNIOR
  • Data: Mar 11, 2011


  • Show Abstract
  • O principal objetivo deste trabalho é desenvolver um ambiente que permite a comunicação do simulador de processos químicos HYSYS com medidores e atuadores de uma rede industrial Foundation Fieldbus. O ambiente é considerado híbrido por possuir uma parte real (a rede industrial) e uma parte simulada (o processo) com os sinais de controle e medição sendo reais.O ambiente é bastante flexível, permitindo a reprodução de diversas dinâmicas típicas de processos industriais sem a necessidade de alteração na rede física, possibilitando gerar diversas situações existentes em um ambiente industrial real. Então, no presente trabalho, a dinâmica utilizada é de uma coluna de destilação simulada no HYSYS e as suas variáveis são medidas e controladas pelos dispositivos da rede industrial Foundation Fieldbus.

12
  • TULLIO EMMANUEL MESSIAS RAPOSO
  • Desenvolvimento e Testes de Software de um Receptor de GPS para Uso Espacial

  • Advisor : FRANCISCO DAS CHAGAS MOTA
  • COMMITTEE MEMBERS :
  • FRANCISCO DAS CHAGAS MOTA
  • GILVAN LUIZ BORBA
  • MÁRIO SARCINELLI FILHO
  • Data: Mar 25, 2011


  • Show Abstract
  • Veículos espaciais se movem com velocidades elevadas e sofrem mudanças bruscas de aceleração. Então, para que um receptor de GPS possa calcular soluções de navegação estando a bordo de tais veículos, o efeito Doppler deve ser levado em consideração durante os processos de aquisição e rastreio de sinais de satélites. Assim, para que o receptor submetido à alta dinâmica comporte os deslocamentos de frequência no sinal recebido, decorrentes desse efeito, é necessário ajustar sua largura de banda de varredura de frequências e aumentar a ordem de sua malha de rastreio. Este trabalho apresenta as modificações no software no GPS Orion, um receptor de arquitetura aberta da GEC Plessey Semiconductors, hoje Zarlink, a fim de torná-lo apto a gerar soluções de navegação em veículos submetidos à alta dinâmica, especialmente satélites de órbita baixa. A plataforma de desenvolvimento GPS Architect, comercializada pela mesma empresa, foi utilizada para dar suporte às modificações. Além disso, são apresentadas as características do Monitor GPS Aeroespacial, uma ferramenta computacional desenvolvida para monitorar as soluções de navegação calculadas pelo receptor de GPS através de gráficos. Apesar de não ter sido possível fazer simulações em alta dinâmica com as modificações de software implementadas no receptor, verificou-se seu funcionamento satisfatório, em regime estacionário, fazendo uso, inclusive, da nova interface gráfica. A dissertação apresenta ainda os resultados do experimento Receptor de GPS para Aplicações Aeroespaciais, obtidos com a participação do receptor numa missão suborbital, a Operação Maracati 2, em dezembro de 2010, utilizando uma malha de rastreio de portadora digital de segunda ordem. Apesar de um incidente ocorrido momentos antes do lançamento ter prejudicado a navegação efetiva do receptor, foi observado que o experimento funcionou adequadamente, rastreando e adquirindo novos satélites durante o voo do foguete VSB-30.

13
  • BRUNO LEONARDO MENDES TAVARES DA SILVA
  • IMPLEMENTAÇÃO DE PROCESSADOR BANDA BASE OFDMA PARA DOWNLINK LTE EM FPGA

  • Advisor : IVAN SARAIVA SILVA
  • COMMITTEE MEMBERS :
  • IVAN SARAIVA SILVA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • ANTONIO CARLOS CAVALCANTI
  • Data: Mar 31, 2011


  • Show Abstract
  • Este trabalho trata da implementação de um transmissor banda base em hardware reconfigurável para downlink LTE. O LTE (Long Term Evolution)  ou  3G LTE compreende ao último estágio de desenvolvimento das tecnologias chamadas de 3G (Telefonia Móvel de Terceira Geração) que provê um incremento nas taxas de dados e maior eficiência e flexibilidade na transmissão com emprego de técnicas avançadas de antenas e de técnicas de transmissão de múltiplas portadoras. Esta tecnologia aplica em sua camada física a técnica OFDMA para geração de sinais e mapeamento dos recursos físicos no downlink e tem como base teórica à técnica de múltiplas portadoras OFDM. Com recente finalização das especificações da tecnologia LTE, diversas soluções em hardware tem sido propostas e desenvolvidas, principalmente, ao nível de processamento de símbolo em que a implementação do transmissor OFDMA em banda base é comumente considerada, visto que ela é também considerada como arquitetura básica de outras importantes aplicações. Para implementação do transmissor, hardwares reconfiguráveis oferecidos por dispositivos como FPGA são considerados que visam não só atender os altos requisitos de flexibilidade e adaptabilidade do LTE como também oferecem a possibilidade de uma implementação rápida e eficiente. A implementação do transmissor em hardware reconfigurável atendeu as especificações da camada física LTE bem como se mostrou flexível o suficiente para atender outros padrões e aplicações que utilizem o transmissor OFDMA como arquitetura básica de seus sistemas. Os resultados obtidos através de simulação e verificação funcional do sistema atestam a funcionalidade e a flexibilidade do transmissor implementado

14
  • LEONARDO TELINO DE MENESES
  • Automação da Detecção de Fraudes em Sistemas de Medição de Energia Elétrica Utilizando Lógica Fuzzy e Ambiente SCADA.

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE BEZERRA DE MENEZES FILHO
  • Data: Apr 4, 2011


  • Show Abstract
  • Este trabalho apresenta uma proposta para automação da detecção de fraudes em sistemas de medição de energia elétrica utilizando Lógica Fuzzy em ambiente SCADA.  A solução consiste na coleta de variáveis em pontos de medição de energia elétrica, tais como tensão, corrente, demanda, condições angulares de diagramas fasoriais de tensões e correntes, quedas de consumo e de demanda entre períodos de faturamento e a tratativa destes parâmetros via Lógica Fuzzy fazendo uso do conhecimento de especialistas na área.  Os valores coletados via supervisório são tratados de forma  Fuzzy , em algoritmo de engenharia,  e  a saída do sistema informa ao usuário  quais as possibilidades de fraude no sistema de medição da unidade consumidora cuja memória de massa das variáveis coletadas tenha sido pesquisada pelo algoritmo e assim  estabelece graus de possibilidades para estas ocorrências. A importância da solução apresentada é função da necessidade de o setor elétrico reduzir o alto índice de perdas que já superou vinte por cento .  Trata-se portanto de um sistema especialista para tomada de decisão buscando assertividade e disparo de ações de campo com direcionamento ao problema a ser encontrado, minimizando os impactos negativos de visitas improdutivas de inspeção em unidades consumidoras. O sistema foi testado – e validado – fazendo-se uso de banco de dados real de concessionária de distribuição de energia elétrica, cuja coleta foi realizada por sistema supervisório já existente e a tratativa dos dados foi implementada pela proposta Fuzzy apresentada e pelo algoritmo neste trabalho desenvolvido.


15
  • PAULO ANDERSON HOLANDA CAVALCANTE
  • Localização de Faltas em Linhas de Transmissão usando Morfologia Matemática

  • Advisor : MADSON CORTES DE ALMEIDA
  • COMMITTEE MEMBERS :
  • DARLAN ALEXANDRIA FERNANDES
  • MADSON CORTES DE ALMEIDA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • Data: Apr 19, 2011


  • Show Abstract
  • Devido à desregulamentação do setor elétrico, as concessionárias de energia tem sido impelidas a buscar procedimentos técnicos para se tornarem mais competitivas. Nesse contexto, a localização de faltas em sistemas de energia elétrica é um problema de relevância crescente. Por causa de sua extensão, uma linha de transmissão é o componente do sistema de energia mais susceptível a ocorrência de faltas. Após a ocorrência de uma falta, é desejável que a equipe de manutenção localize-a rapidamente para extingui-la.
    De modo geral, existem duas classes de métodos principais para localização de faltas em linhas de
    transmissão de energia elétrica. Na primeira classe, utilizam-se medidas dos componentes fundamentais de tensão e corrente coletadas em um ou nos dois terminais da linha de transmissão monitorada. Essas medidas são posteriormente processadas para obtenção de uma impedância aparente que está relacionada com a posição da falta. A segunda classe é baseada na detecção dos instantes de chegadas das ondas viajantes de tensão e/ou corrente associados à falta. Nessa classe a implementação pode ser baseada em medidas realizadas em um ou nos dois terminais da linha. A técnica de localização de faltas investigada neste trabalho se encaixa na segunda classe.
    Após a ocorrência de uma falta em uma linha de transmissão, sinais transitórios de tensão e corrente
    superpostos ao sinal de freqüência fundamental se propagam do ponto da falta em direção aos terminais da linha na forma de ondas viajantes. Para detectar os instantes de chegada das frentes das ondas aos terminais monitorados da linha é necessário utilizar ferramentas matemáticas capazes de extrair essas informações dos sinais de tensão e/ou corrente.
    Uma das ferramentas mais difundida para a análise de sinais é a transformada de Fourier. O uso dessa transformada baseia-se na decomposição do sinal em bases senoidais e cossenoidais. Embora seja bastante difundida, a transformada de Fourier não é eficaz para decompor sinais transitórios por utilizarem janela de largura fixa. Uma segunda opção é a transformada wavelet, que se diferencia da transformada de Fourier porque o sinal é decomposto em bases localizadas tanto no domínio da freqüência quanto no domínio do tempo. Uma alternativa às transformadas de Fourier e wavelet para análise de sinais transitórios são os chamados filtros morfológicos. Em contraste com aquelas transformadas lineares, os filtros morfológicos são operadores não lineares baseados apenas em operações de adição e subtração acompanhadas da extração de máximos e mínimos de conjuntos discretos. Apresentam, portanto, a vantagem de serem mais eficientes computacionalmente.
    Neste trabalho serão desenvolvidas metodologias para localização de faltas em linhas de transmissão baseadas nos instantes de chegadas das frentes de ondas de tensão e/ou corrente observadas nos terminais de linhas de transmissão sob falta. Para a determinação dos instantes de chegada das frentes de onda serão utilizadas técnicas baseadas na morfologia matemática. Serão desenvolvidas e analisadas metodologias que utilizam informações de um ou dois terminais da linha de transmissão.

16
  • DIOGO LEITE REBOUCAS
  • Utilização de redes neurais artificiais para detecção e diagnóstico de falhas

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • Data: Jun 21, 2011


  • Show Abstract
  • Em um processo real, todos os recursos utilizados, sejam físicos ou desenvolvidos em software, estão sujeitos a interrupções ou a comprometimentos operacionais. Contudo, nas situações em que operam os sistemas críticos, qualquer tipo de problema pode vir a trazer grandes consequências. Sabendo disso, este trabalho se propõe a desenvolver um sistema capaz de detectar a presença e indicar os tipos de falhas que venham a ocorrer em um determinado processo. Para implementação e testes da metodologia proposta, um sistema de tanques acoplados foi escolhido como modelo de estudo de caso. O sistema a ser desenvolvido deverá gerar um conjunto de sinais que notifiquem o operador do pro- cesso e que possam vir a ser pós-processados, possibilitando que sejam feitas alterações nas estratégias ou nos parâmetros dos controladores. Em virtude dos riscos envolvidos com relação à queima dos sensores, atuadores e amplificadores existentes na planta real, o conjunto de dados das falhas será gerado computacionalmente e os resultados coletados a partir de simulações numéricas do modelo do processo, não havendo risco de dano aos equipamentos. O sistema será composto por estruturas que fazem uso de Redes Neurais Artificiais, treinadas em modo /offline/ pelo software matemático Matlab.

17
  • ANNA GISELLE CAMARA DANTAS RIBEIRO RODRIGUES
  • Implementação de um Controlador PID Embarcado Aplicado ao Controle de Pressão Arterial

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • DANIELLE SIMONE DA SILVA CASILLO
  • GILBERT AZEVEDO DA SILVA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Jun 27, 2011


  • Show Abstract
  • A hipertensão arterial é uma doença perigosa que pode causar danos graves a saúde do paciente. Em algumas situações a necessidade de controlar essa pressão é ainda maior, como em procedimentos cirúrgicos e em pacientes pós-cirurgicos. Para diminuir as chances de uma complicação, é necessário reduzir a pressão arterial o mais rápido possível. A infusão contínua de drogas vasodilatadoras, como o nitroprussiato de sódio (NPS), reduz rapidamente a pressão arterial na maioria dos pacientes, evitando problemas maiores. Manter a pressão arterial pretendida exige um monitoramento constante e um ajuste frequente na taxa de infusão da droga. O controle manual desse procedimento feito por um profissional é muito desgastante, demorado e, como resultado, muitas vezes de má qualidade.
    Desta forma, o objetivo desse trabalho é o projeto e implementação de um banco de controladores sintonizados e baseados em modelos de pacientes visando encontrar o PID adequado para ser embarcado em uma placa de circuito integrado programável (PIC), uma vez que um PIC possui um custo reduzido,  menor em tamanho, e menor no consumo de energia. Para obter melhores resultados no controle da pressão arterial e escolha do controlador mais adequado são utilizados algoritmos de sintonia, técnicas de identificação de sistemas e preditor de Smith.

    O presente trabalho também apresenta um  sistema de monitoramento que auxilia na detecção de anomalias e agiliza o processo de atendimento ao paciente.

18
  • JOAO MARCOS TEIXEIRA LACERDA
  • SOA-DB: Uma Arquitetura Embarcada Orientada a Serviço Para Acesso A Dispositivos Biomédicos

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • GLAUCIO BEZERRA BRANDAO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • FILIPE DE OLIVEIRA QUINTAES
  • Data: Jun 30, 2011


  • Show Abstract
  • A grande diversidade na arquitetura de dispositivos biomédicos, aliada aos seus diferentes protocolos de comunicação, tem dificultado a implementação de sistemas que necessitam realizar o acesso a esses dispositivos. Diante dessas diferenças, surge a necessidade de prover o acesso a esses de forma transparente. Neste sentido, o presente trabalho propõe uma arquitetura embarcada, orientada a serviço, para acesso a dispositivos biomédicos, como forma de abstrair o mecanismo de escrita e leitura de dados nesses dispositivos, contribuindo desta maneira, para o aumento na qualidade e produtividade dos sistemas biomédicos, de forma a possibilitar com que, o foco da equipe de desenvolvimento de softwares biomédicos, seja quase que exclusivamente voltado aos seus requisitos
    funcionais.

19
  • RENATO QUARENTEI GARDIMAN
  • Visão Estéreo com Correspondência Esparsa com Características Extraídas pelo Método SURF

  • Advisor : LUIZ EDUARDO CUNHA LEITE
  • COMMITTEE MEMBERS :
  • ALEJANDRO CESAR FRERY ORGAMBIDE
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Jul 4, 2011


  • Show Abstract
  • Visão Estéreo é um conjunto de técnicas e algoritmos voltados para extração de informação 3D do objeto ou cena que estejam sendo observados. A correspondência entre pixels que representam o mesmo ponto do mundo em imagens estéreo é um ponto chave para um bom desempenho de qualquer sistema de visão estéreo. O presente trabalho aborda uma arquitetura de hardware e os métodos desenvolvidos para extração de pontos característicos como o SURF - Speeded Up Robust Features com o objetivo de usá-los para encontrar a correspondencia entre as duas imagens estéreo e montar um mapa de disparidade esparsa que pode ser posteriormente aproximado para um mapa denso usando-se técnicas de aproximação como interpolação por exemplo. Resultados de implementações são apresentados assim como um conjunto de técnicas e conceitos necessários para a realização e o entendimento do trabalho.

20
  • JULIANO RAFAEL SENA DE ARAUJO
  • Métricas de Desempenho para Sistema de Alarmes de Processos
    Industriais

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DIEGO RODRIGO CABRAL SILVA
  • JOSE ALVARO DE PAIVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jul 4, 2011


  • Show Abstract
  • A evolução da automação nos últimos anos tornou possível o monitoramento contínuo dos processos de plantas industriais. Com esse avanço, a quantidade de informação que os sistemas de automação estão submetidos aumentou significativamente. Os alarmes gerados pelos equipamentos de monitoração são um dos principais responsáveis por esse aumento, sendo que eles geralmente são implantados nas plantas industriais sem uma metodologia formal, o que acarreta um aumento do número de alarmes gerados, sobrecarregando, assim, os sistemas de alarmes e por consequência os operadores dessas plantas. Neste contexto, o trabalho de gerenciamento de alarmes surge com o objetivo de definir uma metodologia formal para a instalação de novos equipamentos e detectar problemas nas configurações existentes. Esta dissertação visa propor um conjunto de métricas para a avaliação dos sistemas de alarmes já implantados, de forma que seja possível identificar a “saúde” deste sistema analisando-se os índices propostos e comparando-os com os parâmetros definidos em normas técnicas da área de gestão de alarmes. Além disso, as métricas permitirão o acompanhamento do trabalho de gerenciamento de alarmes, verificando se o mesmo está melhorando a qualidade do sistema de alarme. Para validação das métricas propostas, utilizou-se dados
    provenientes de plantas de processo reais da indústria petroquímica.

21
  • DIEGO RODRIGUES DE CARVALHO
  • Uma arquitetura para detecção de transientes em sinais de eletrocardiograma sobre o protocolo IEEE 802.3

  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • GLAUCIO BEZERRA BRANDAO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • FILIPE DE OLIVEIRA QUINTAES
  • Data: Jul 11, 2011


  • Show Abstract
  •     A ocorrência de transientes em sinais de eletrocardiograma (ECG) é um indicativo de um fenômeno elétrico externo ao coração, sendo a identificação de transientes a metodologia mais utilizada na análise médica desde que o eletrocardiógrafo (dispositivo responsável pelo aferimento dos sinais de eletrocardiograma) foi inventado, porém, a freqüência de ocorrência desses eventos é muito baixa o que motiva a criação de uma arquitetura para fazer o pré-processamento desse sinal em busca da identificação de transistes. O presente trabalho propõe um método baseado na energia da transformada Hilbert do sinal de eletrocardiograma, sendo uma alternativa aos métodos baseados em morfologia do sinal. Essa informação determinará a formação de quadros do protocolo PM-AH responsável por transmitir os sinais de ECG através de uma rede de computadores do tipo IEEE 802.3 até um dispositivo computacional. Que por sua vez poderá realizar um processamento para fazer a classificação automática do sinal ou apresentá-lo para um médico realizar essa classificação de forma manual.

22
  • RODRIGO SOARES SEMENTE
  • Otimização de algoritmos Criptográficos para redes de Sensores Atuadores Sem-fio para Poços do Tipo Plunger Lift

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ANDRES ORTIZ SALAZAR
  • ANTONIO RAMIREZ HIDALGO
  • Data: Jul 22, 2011


  • Show Abstract
  • As redes de sensores e atuadores sem fio especificadas pelo padrão IEEE 802.15.4, estão cada vez mais sendo aplicadas à instrumentação, como na instrumentação de poços de petróleo com completação do tipo Plunger Lift. Devido às características específicas do ambiente que estão sendo instaladas, verificamos os riscos ao ter a segurança da rede comprometida, apresentando vários cenários de ataques e os danos potenciais dos mesmos. Verificamos assim a necessidade de um estudo mais detalhado de segurança dessas redes, que preconiza o uso de algoritmos de criptografia, como o AES-128 bits e RC6. Assim implementamos então os algoritmos AES-128 e RC6, em um microcontrolador de apenas 8 bits, e estudamos detalhadamente suas características de desempenho, crucial para aplicações embarcadas. A partir desses resultados desenvolvemos um algoritmo criptográfico híbrido, ACH, que apresentou características intermediarias entre o AES e o RC6, mais apropriadas para uso em aplicações com limitações de consumo de energia e memória. Também apresentamos um estudo comparativo da qualidade de segurança entre os três algoritmos, provando a capacidade criptográfica do ACH.

23
  • MADSON ALYSSON AUGUSTO VIEIRA
  • Sistema de Comunicação de Dados via Rede Elétrica para um Motor de Indução Trifásico

     

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FILIPE DE OLIVEIRA QUINTAES
  • Data: Jul 25, 2011


  • Show Abstract
  • O PLC (power line communication) designa uma tecnologia que usa geralmente médias e baixas tensões elétricas para prover serviços de telecomunicações. As redes elétricas apresentam características que dificultam a transmissão de sinais, mas com o desenvolvimento de novas tecnologias já é possível a certeza da robustez e viabilidade de transmissões com a tecnologia PLC. Este trabalho tem por proposta elaborar e projetar um sistema de comunicação de dados pela rede elétrica para o monitoramento de variáveis controladas do motor de indução trifásico e bem como estudar os protocolos de comunicação conhecidos da tecnologia PLC e implementá-los em um microcontrolador. Para tal, será utilizado o software Proteus R para simulação dos componentes do sistema e a construção com a placa de circuitos impressa.

24
  • ANDERSON MAX CIRILO DA SILVA
  • Aplicação de Dispositivos de Microondas utilizando Substrato EBG/PBG para comunicações Móveis

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUGO MICHEL CAMARA DE AZEVEDO MAIA
  • HUMBERTO CESAR CHAVES FERNANDES
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • LAERCIO MARTINS DE MENDONCA
  • Data: Jul 26, 2011


  • Show Abstract
  • A sociedade moderna depende de um eficiente sistema de comunicações, capaz de transmitir e receber informações com uma velocidade e confiabilidade maiores a cada momento. A necessidade de dispositivos cada vez mais eficientes faz surgir técnicas de otimização dos dispositivos em microfita, como por exemplo, técnicas para aumentar a largura de banda: substratos mais espessos e estruturas com substratos de Banda Eletromagnética Proibida - EBG (Electromagnetic Band Gap) e Banda Fotônica Proibida - PBG (Photonic Band Gap). Este trabalho tem como objetivo o estudo da aplicação materiais EBG/PBG em substratos de estruturas planares em microfita, mais precisamente em acopladores direcionais em quadratura e em anel e em transformadores de impedâncias. Foi apresentado um estudo das estruturas planares em microfita e dos substratos EBG/PBG. Substratos PBG podem ser usados para otimizar a irradiação pelo ar, reduzindo assim a ocorrência de ondas superficiais e a conseqüente difração de borda responsável pela degradação do diagrama de radiação. Através de programas específicos em FORTRAN obtiveram-se as freqüências e acoplamentos para cada estrutura. São obtidos resultados da freqüência e acoplamentos dos dispositivos, variando-se banda de freqüência utilizada (sistemas de comunicação celular e Wimax) e a permissividade do substrato, comparando-se os resultados de materiais convencionais e materiais PBG nas polarizações s e p.

25
  • CLAUDIO ALEXANDRE SCHNEIDER
  • SAMVC - Sistema de Autoria de Museus Virtuais Colaborativos

  • Advisor : RUMMENIGGE RUDSON DANTAS
  • COMMITTEE MEMBERS :
  • CLAUDIA MARIA FERNANDES ARAÚJO RIBEIRO
  • LUIZ MARCOS GARCIA GONCALVES
  • RUMMENIGGE RUDSON DANTAS
  • Data: Jul 26, 2011


  • Show Abstract
  • A utilização de objetos gráficos tridimensionais (3D) em aplicações multimídias vem ganhando cada vez mais espaço nos meios de comunicação. Redes com altas taxas de transmissão, computadores com grande capacidade de processamento gráfico impulsionam e popularizam tais aplicações tridimensionais. Os domínios das aplicações 3D variam desde aplicações militares, entretenimento até aplicações voltadas para educação. Dentro das aplicações voltadas a educação, destacamos as aplicações que criam cópias virtuais de espaços culturais, como museus. Através dessa cópia, o usuário pode visitar virtualmente um museu, perceber outros usuários, se comunicar, trocar informações sobre obras, etc. Desse modo, possibilitando a visita remota de museus fisicamente distantes dos usuários. Um grande problema de tais ambientes virtuais reside na sua atualização. Por lidar com mídias diversas (texto, imagens, sons, e modelos 3D), a sua manipulação e conseqüente atualização em um ambiente virtual exige pessoal com conhecimento especializado. Em se falando de museus, eles dificilmente possuem em sua equipe pessoas com tal perfil. Dentro do projeto GT-MV (Grupo de Trabalho de Museus Virtuais), financiado pela RNP (Rede Nacional de Ensino e Pesquisa) propomos um portal para o cadastro, alteração e visita colaborativa de museus virtuais do Brasil. A atualização, seja ela relacionada a obras ou espaço físico, de um sistema com escala nacional como esse, ficaria impossibilitada se realizada apenas pela equipe do projeto. Dentro desse cenário, propomos a modelagem e implementação de uma ferramenta que permita a edição de espaços virtuais de uma maneira fácil e intuitiva, se comparado com as ferramentas atualmente disponíveis. Dentro do contexto do GT-MV, aplicamos o SAMVC (Sistema de Autoria de Museus Virtuais Colaborativos) a museus onde os curadores constroem o museu 3D a partir de uma planta baixa (2D). O sistema, a partir dessas informações bidimensionais, recria o equivalente em três dimensões. Com isso, através de pouco ou nenhum treinamento, membros das equipes de cada museu podem ficar responsáveis pela sua atualização no sistema.

26
  • ODAILSON CAVALCANTE DE OLIVEIRA
  • Desacoplamento de um Gerador Síncrono Através de um Controle Adaptativo por Modelo de Referência Baseado em Funções de Base Radial

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • GUILHERME DE ALENCAR BARRETO
  • JORGE DANTAS DE MELO
  • Data: Jul 28, 2011


  • Show Abstract
  • Neste trabalho será apresentada uma técnica alternativa para desacoplamento e controle de sistemas não lineares baseada numa rede neural RBF (Radial Basis Functions). Essa técnica é aplicada ao modelo de um gerador síncrono cujas variáveis de saída são acopladas. A RBF realizará o desacoplamento das saídas: ângulo do rotor e fluxo concatenado. Tal estratégia não exige conhecimento do sistema e devido a natureza das funções de base radial mostra-se estável, tanto na presença de incertezas como de distúrbios, além de ser bastante simples quando aplicada ao controle. Será discutido como foi projetada a rede RBF para desacoplamento do gerador síncrono. O sistema não linear em questão possui duas entradas e duas saídas, o que caracteriza um sistema não linear MIMO (Multiple Input Multiple Output). Os pesos que interligam as camadas ocultas e de saída da rede neural são ajustados utilizando uma lei adaptativa em tempo real. O sistema de desacoplamento faz uso dos sinais filtrados da saída e dos sinais de erros entre as saídas do sistema e as saídas dos modelos referência para produzir um sinal de controle. Assim cada saída do sistema é forçada a se comportar conforme uma dinâmica desejada. Será mostrada a prova de estabilidade através do método de funções de Lyapunov. Serão apresentadas simulações do desacoplamento e robustez do sistema.

27
  • MARCELO HENRIQUE RAMALHO NOBRE
  • Análise de Desempenho de Redes WirelessHART Baseada em Simulação

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • DENNIS BRANDAO
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jul 29, 2011


  • Show Abstract
  • A utilização de redes sem fio tem crescido nos últimos anos, de modo que podemos perceber sua presença em cenários que vão desde ambientes industriais ao acesso a internet e a transmissão de vídeo e voz em tempo real. Especificamente tratando-se dos ambientes industriais, os requisitos de confiabilidade e escalabilidade tornam-se foco principal de preocupação das empresas. Visando dar embasamento a tais requisitos dos novos protocolos de comunicação, a simulação se torna uma alternativa de baixo custo e alta escalabilidade. No presente trabalho será proposto um módulo de simulação WirelessHART para o simulador de redes Network Simulator 3 tendo em vista aceitação que ambos possuem no atual contexto de pesquisa.

28
  • GILMARA LINHARES DE ARAUJO
  • Estudo de Antenas Planares Multicamadas com Patches Fractais para Aplicações em Redes sem Fio

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • SANDRO GONCALVES DA SILVA
  • Data: Jul 29, 2011


  • Show Abstract
  • Com o crescente avanço das tecnologias sem fio faz-se necessário a criação de antenas cada vez mais compactas que operem em várias frequências simultaneamente e apresentem grandes larguras de banda. O comportamento multibanda desses dispositivos é importante para atender as necessidades dos modernos equipamentos de comunicação sem fio que unem em um único aparelho diversas tecnologias. Atualmente, com o surgimento de tecnologias como o Wimax (Worldwide Interoperability for Microwave Access), Bluetooth, Wi-Fi (Wireless Fidelity), entre outras, as pesquisas neste campo das telecomunicações tem alcançado grandes avanços, pois as antenas de microfita são amplamente utilizadas em diversos sistemas de comunicação sem fio devido às características que apresentam: facilidade de adaptação a superfícies planares, superfícies não-planares, baixo peso, tamanho reduzido e baixo custo. À medida que aumenta a complexidade dos sistemas de comunicações, novas estruturas são desenvolvidas a fim de atender aos requisitos de funcionamento e aperfeiçoamento do desempenho desses sistemas. Para isso, agregam-se a estas estruturas diversas técnicas de melhoramento e adaptação às novas tecnologias. Para isso uma das alternativas encontradas foi a união de conceitos fractais à teoria das antenas de microfita, que vem apresentando bons resultados em pesquisas desenvolvidas atualmente devido algumas propriedades apresentadas pelos fractais, como por exemplo, a auto-similaridade que possibilita às antenas fractais apresentarem características multibanda e maiores larguras de banda. Outra característica das antenas fractais é a possibilidade de arranjos de antenas.
    O objetivo deste trabalho é a análise de antena patch fractal de Koch com multicamadas com plano de terra inclinado. A variação da inclinação do plano de terra faz com que a antena apresente maiores larguras de banda e bom casamento de impedâncias. Essa antena consiste de três camadas dielétricas sobrepostas. Na primeira camada encontra-se o patch retangular com inset-feed (nível zero) o qual irá alimentar, por indução eletromagnética, as demais camadas superiores - segunda e terceira camadas - que contêm os patches com contornos fractais de Koch (níveis 1 e 2).  A eficiência da inclinação do plano de terra foi investigada por meio de simulações realizadas com o software comercial Ansoft HFSS comparando-se os resultados obtidos nas simulações com os resultados obtidos experimentalmente. A validação dos resultados é obtida neste estudo através da comparação entre os resultados simulados e medidos.

29
  • VITOR MENEGHETTI UGULINO DE ARAÚJO
  • Técnicas de SLAM Visual sem Extração de Primitivas Geométricas da Imagem

  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ANDRE MACEDO SANTANA
  • PABLO JAVIER ALSINA
  • Data: Jul 29, 2011


  • Show Abstract
  • Na Localização e Mapeamento Simultâneos (SLAM - Simultaneous Localization and Mapping), um robô posicionado em uma localização desconhecida de um ambiente qualquer deve ser capaz de criar uma perspectiva deste ambiente (um mapa) e se localizar no mesmo simultaneamente, utilizando apenas informações captadas pelos sensores do robô e sinais de controle conhecidos. Recentemente, impulsionados pelo avanço computacional, trabalhos nessa área propuseram usar câmera de vídeo como sensor e surgiu assim o SLAM Visual. Este possui várias abordagens e a grande maioria delas funcionam, basicamente, extraindo características do ambiente, calculando as devidas correspondências e através destas, e de filtros estatísticos, estimam os parâmetros necessários. Neste trabalho foi apresentado um sistema de SLAM Visual Monocular queutiliza registro direto de imagem para calcular o erro de reprojeção entre imagens e métodos de otimização que minimizam esse erro e assim obter os parâmetros relativos a pose do robô e o mapa do ambiente diretamente dos pixels das imagens. Dessa forma as etapas de extração e correspondência de características são dispensadas, possibilitando que nosso sistema funcione bem em ambientes onde as abordagens tradicionais teriam dificuldades. Além disso, ao se abordar o problema do SLAM da forma proposta nesse trabalho evitamos um problema muito comum nas abordagens tradicionais, conhecido como propagação do erro. Preocupando-se com o elevado custo computacional dessa abordagem foram testados vários tipos de métodos de otimização afim de achar um bom equilíbrio entre boas estimativas e tempo de processamento. Os resultados apresentados nesse trabalho comprovam o funcionamento desse sistema em diferentes ambientes.

30
  • BEZALIEL ALBUQUERQUE DA SILVA PIRES
  • Maximização da Penetração da Geração Distribuída Através do Algoritmo de Otimização Nuvem de Partículas

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • CLOVIS BOSCO MENDONCA OLIVEIRA
  • JOSE TAVARES DE OLIVEIRA
  • JOÃO PAULO ABREU VIEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Aug 3, 2011


  • Show Abstract
  • A geração distribuída, especialmente a partir de fontes renováveis, aumenta a sua participação na matriz elétrica nacional, a cada ano.

    Este trabalho objetiva analisar a penetração de geração distribuída em um sistema de distribuição em alta tensão (69 kV), localizado no Estado do Rio Grande do Norte. A proposta inclui o desenvolvimento de uma metodologia para definição dos valores máximos de potência ativa possíveis de serem injetados em barras pré-definidas da rede, considerando a possibilidade de múltiplas propostas de acesso de unidades geradoras.

    A definição desses valores máximos é obtida a partir de um estudo de otimização, em que as novas perdas não devem superar aquelas do caso base, ou seja, sem a presença da geração distribuída. As restrições de carregamentos e tensões do sistema também são respeitadas. Para tratar o problema de otimização utiliza-se o algoritmo Nuvem de Partículas, em um programa desenvolvido em plataforma SCILAB.

31
  • DIEGO ANTONIO DE MOURA FONSECA
  • Desenvolvimento de uma Planta Piloto para Estudos de Poços de Petróleo Produzindo por Plunger Lift

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • CARLA WILZA SOUZA DE PAULA MAITELLI
  • OSCAR GABRIEL FILHO
  • PABLO JAVIER ALSINA
  • Data: Aug 10, 2011


  • Show Abstract
  • Este trabalho se propõe a descrever uma planta piloto para poços de petróleo equipados com elevação artificial por plunger lift. Além de um tamanho reduzido (22 metros) e estar sobre a superfície, a planta possui parte de sua estrutura em acrílico transparente, permitindo a fácil visualização de fenômenos inerentes ao método. A formação rochosa donde o poço da planta piloto extrai seus fluidos (água e ar) é simulada por uma casa de máquinas onde estão localizados o compressor e a bomba d’água responsáveis pela produção de ar e água. Para manter as vazões de ar e água com valores conhecidos e controlados as linhas que conectam a casa de máquina ao fundo do poço são equipadas com sensores de vazão e válvulas. É desenvolvido um sistema supervisório que permite ao usuário uma monitoração em tempo real das pressões e vazões envolvidas no processo. A partir do supervisório é possível ainda o usuário escolher a forma como serão controlados os ciclos do processo, se por tempo, por pressão ou manualmente, e definir os valores de vazão de ar a água utilizado durantes os ciclos. Esses valores podem ser definidos a partir de um set point ou a partir da porcentagem de abertura das válvulas. São apresentados resultados de testes realizado na planta utilizando as formas de controle mais usuais: por tempo e por pressão no revestimento. Por fim, estes serão confrontados com resultados gerados por um simulador configurados com as características da planta piloto.

32
  • ALEXANDRE GOMES DE LIMA
  • Classificador Neural Híbrido para Imagens Obtidas por Sensoriamento Remoto

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • ANTONIO DE PADUA DE MIRANDA HENRIQUES
  • HELIANA BEZERRA SOARES
  • Data: Aug 12, 2011


  • Show Abstract
  • O sensoriamento remoto é uma tecnologia de extrema importância na atualidade, permitindo a captação de dados da superfície terrestre que são utilizados com diversas finalidades, entre as quais, o acompanhamento do meio-ambiente. Uma das aplicações principais do sensoriamento remoto é a geração de mapas temáticos e posterior levantamento de áreas específicas a partir de imagens geradas por sensores orbitais ou sub-orbitais. Métodos de classificação de padrões são utilizados na implementação de rotinas computacionais que automatizem essa atividade. As redes neurais artificiais apresentam-se como métodos alternativos viáveis aos classificadores estatísticos tradicionais, apresentando, em determinadas situações, comportamento superior. Este trabalho tem como objetivo principal propor um classificador baseado nas redes neurais de função de base radial e growing neural gas e que apresenta algumas vantagens em relação à utilização individual de redes neurais. A idéia principal é utilizar as características incrementais da rede growing neural gas para otimizar o quantidade de centros da rede de função de base radial com o intuito de obter um classificador altamente eficaz. Para atestar a relevância da proposta, é apresentado um estudo de caso no qual o desempenho do classificador proposto foi superior ao do classificador bayseano por máxima verossimilhança.

33
  • ALEXANDRE GOMES DE LIMA
  • Classificador Neural Híbrido para Imagens Obtidas por Sensoriamento Remoto

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • HELIANA BEZERRA SOARES
  • ANTONIO DE PADUA DE MIRANDA HENRIQUES
  • Data: Aug 12, 2011


  • Show Abstract
  • O sensoriamento remoto é uma tecnologia de extrema importância na atualidade, permitindo a captação de dados da superfície terrestre que são utilizados com diversas finalidades, entre as quais, o acompanhamento do meio-ambiente. Uma das aplicações principais do sensoriamento remoto é a geração de mapas temáticos e posterior levantamento de áreas específicas a partir de imagens geradas por sensores orbitais ou sub-orbitais. Métodos de classificação de padrões são utilizados na implementação de rotinas computacionais que automatizem essa atividade. As redes neurais artificiais apresentam-se como métodos alternativos viáveis aos classificadores estatísticos tradicionais, apresentando, em determinadas situações, comportamento superior. Este trabalho tem como objetivo principal propor um classificador baseado nas redes neurais de função de base radial e growing neural gas e que apresenta algumas vantagens em relação à utilização individual de redes neurais. A idéia principal é utilizar as características incrementais da rede growing neural gas para otimizar o quantidade de centros da rede de função de base radial com o intuito de obter um classificador altamente eficaz. Para atestar a relevância da proposta, é apresentado um estudo de caso no qual o desempenho do classificador proposto foi superior ao do classificador bayseano por máxima verossimilhança.

34
  • FABIO ARAUJO DE LIMA
  • Sistema Automatizado para o Aproveitamento de Água Cinza e Azul com Controle de pH Utilizando Lógica Fuzzy

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSE BEZERRA DE MENEZES FILHO
  • Data: Aug 31, 2011


  • Show Abstract
  • A cada dia a escassez de água se torna um problema mais grave e que atinge diretamente a sociedade mundial. Estudos são dirigidos no intuito de conscientizar a população do uso racional desse bem natural que é imprescindível à sobrevivência. Somente 0,007% das águas disponíveis no globo apresentam acesso fácil e podem ser consumidas por seres humanos, sendo encontradas em rios, lagos, etc. Para melhor proveito das águas utilizadas em residências e pequenos estabelecimentos, projetos de reuso são muitas vezes implementados, implicando, sua maioria, em economia para os clientes das concessionárias de água. Os projetos de reuso envolvem as mais diversas áreas da engenharia, podendo ser citadas a engenharia ambiental, engenharia química e também a engenharia elétrica, essa última, responsável pelo controle dos processos, que tem por objetivo tornar a água cinza ideal para o consumo, ou apenas para utilização em regas de jardins, descargas sanitárias, entre outros.

    A água, possui várias características que devem ser levadas em consideração, quando em se tratando com relação ao seu reuso, algumas delas são, turbidez, temperatura, condutividade elétrica, pH. Nesse trabalho é apresentada uma proposta de controle de pH (potencial hidrogeniônico), através de microcontrolador, utilizando-se como estratégia de controle lógica fuzzy. O controlador foi desenvolvido no toolbox fuzzy do software Matlab.

35
  • MARCILIO DE PAIVA ONOFRE FILHO
  • Lógica Fuzzy Para Controle de pH em um Processo Petrolífero

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRE LAURINDO MAITELLI
  • GIOVANNI LOUREIRO FRANCA DE MENDONCA
  • Data: Sep 2, 2011


  • Show Abstract
  • Propõem-se neste trabalho a concepção e a avaliação do desempenho de um controlador Fuzzy-PI, tipo Takagi-Sugeno-Kang, para o acompanhamento de referências de pH em um tanque reator com agitação contínua. O controlador é projetado para executar a neutralização do pH em plantas industriais, principalmente em unidades encontradas em refinarias de petróleo. O sistema emula, com base no modelo de Hammerstein, uma planta real que se ajusta às mudanças no processo de neutralização do pH, evitando ou reduzindo a necessidade de ressintonia. O desempenho do controlador é avaliado pelos overshoots, pelos tempos de acomodação, pelos índices Integral do valor absoluto do erro (IAE) e Integral do valor absoluto do erro com ponderação do tempo (ITAE), e através de um índice desenvolvido por Goodhart que leva em consideração tanto informações do erro quanto do sinal de controle. O controlador Fuzzy-PI é comparado com controladores PI e PI Escalonado utilizados previamente na planta de teste, cujos resultados estão disponíveis na literatura.

36
  • MÁRCIO EMANUEL UGULINO DE ARAÚJO JÚNIOR
  • Desenvolvimento de um Ambiente Para Sintonia de Controladores Fuzzy Para Dispositivos Móveis

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ANDRE LAURINDO MAITELLI
  • GIOVANNI LOUREIRO FRANCA DE MENDONCA
  • Data: Sep 2, 2011


  • Show Abstract
  • Sistemas inteligentes Fuzzy estão presentes nos mais variados equipamentos, desde eletrodomésticos e máquinas industriais até dispositivos de pequeno porte, como máquinas digitais e aparelhos celulares, sendo utilizados principalmente por lidar com as incertezas inerentes a modelagem dos sistemas reais, que em geral são não lineares. No entanto, as implementações comerciais de sistemas Fuzzy não são de propósito geral e não apresentam portabilidade para diferentes plataformas de hardware. Sobre essas questões, este trabalho apresenta a implementação de um ambiente de desenvolvimento open source composto de um sistema desktop capaz de gerar graficamente um controlador Fuzzy de propósito geral e exportar estes parâmetros para um sistema embarcado com um controlador Fuzzy escrito em Java To Plataform Micro Edition (J2ME), cuja concepção modular o torna portável para qualquer dispositivo móvel que suporte J2ME. Desta forma, a plataforma de desenvolvimento proposta é capaz de gerar todos os parâmetros de um controlador Fuzzy e exportá-lo em arquivo XML. O código responsável pela lógica de controle que se encontra embarcado no dispositivo móvel é capaz de ler o arquivo e iniciar o controlador. Todos os parâmetros de um controlador Fuzzy são configuráveis através do sistema desktop, desde as funções de pertinência e base de regras até o universo de discurso dos termos linguísticos das variáveis de saída. O sistema proposto gera controladores Fuzzy para o modelo de interpolação do tipo Takagi-Sugeno. Como processo de validação e testes da solução proposta, o controlador Fuzzy foi embarcado no dispositivo móvel Sun SPOT® e usado para controle de uma planta de nível da Quanser®, e para comparação do controlador Fuzzy gerado pelo sistema com outros tipos de controladores foi implementado e embarcado no Sun SPOT um controlador PID para a mesma planta de nível.

37
  • FLAVIO GONCALVES DANTAS
  • Controle Vetorial Para Velocidade De Um Motor de Indução Trifásico Utilizando Estimador Filtro de Kalman

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • JOSE ANDRES SANTISTEBAN LARREA
  • Data: Sep 9, 2011


  • Show Abstract
  •  

    Este trabalho descreve o estudo, da simulação computacional e a viabilidade da implementação do controle de velocidade de um motor de indução trifásico 
    utilizado para tal finalidade o FILTRO de KALMAN EXTENDIDO como estimador do fluxo do rotor. A motivação da pesquisa está na utilização de um sistema de 
    controle que não necessite no eixo da maquina, proporcionando desta forma uma considerável redução nos custo de acionamento e manutenção; aumentando 
    da confiabilidade, robustez  e imunidade a ruído além relação ao controle do motor convencional com sensores.

    Esta dissertação apresenta o desenvolvimento de uma simulação computacional com a finalidade de demonstrar o funcionamento do controle vetorial para velocidade de um motor de indução trifásico utilizando método de estimação pelo Filtro de Kalman Estendido, bem como os procedimentos necessários para sua implementação prática. A motivação maior que influenciou a pesquisa está na utilização de um sistema de controle inovador que não necessita de sensores no eixo da máquina (técnica sensorless), proporcionando desta forma uma considerável redução nos custos de acionamentos e manutenção, aumento da confiabilidade, da robustez e da imunidade a ruídos em relação ao controle de motores convencionais com sensores.

     

38
  • LEONARDO GOMES DE PAIVA AMORIM
  • Utilização de Sistemas Dedicados e Protocolos de Rede Aplicados à Eficiência Energética da Iluminação Pública

  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • FILIPE DE OLIVEIRA QUINTAES
  • GLAUCIO BEZERRA BRANDAO
  • PABLO JAVIER ALSINA
  • Data: Nov 14, 2011


  • Show Abstract
  • O sistema de iluminação pública do Natal/RN apresenta problemas recorrentes no aspecto do monitoramento, visto que atualmente não é possível detectar  em tempo real as lâmpadas que estão acesas durante o dia, ou as que estão apagadas (queimadas) durante a noite. Estes fatores depreciam a eficiência dos serviços prestados, bem como, do uso dos recursos energéticos, posto que há desperdício de energia e, consequentemente, de recursos financeiros que poderiam ser aplicados no próprio sistema de iluminação pública. Este trabalho  teve como objetivo a criação de um novo produto em substituição aos atuais relés fotoelétricos utilizados na iluminação publica,  os quais possuem as mesmas funções, como também agregam outras: ligar ou desligar a lâmpada remotamente (flexibilização do controle a partir do uso de algoritmos supervisórios específicos), verificação do status
    da lâmpada (acesa ou apagada) e comunicação sem fio com o sistema através do protocolo ZigBee. Relata-se aqui as etapas de desenvolvimento deste produto e os testes realizados como forma de validar e justificar seu emprego  na  iluminação pública.

39
  • RONALDO MAIA DE MEDEIROS
  • Análise de Desempenho na Rede Metropolitana de Saúde da Universidade Federal do Rio Grande do Norte: um dimensionamento aplicado a Telemedicina e a Telessaúde utilizando QoS baseado no padrão IEEE 802.1Q

  • Advisor : RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • COMMITTEE MEMBERS :
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • FILIPE DE OLIVEIRA QUINTAES
  • Data: Nov 14, 2011


  • Show Abstract
  • É notório o avanço das redes de computadores nas últimas décadas, seja em relação às taxas de transmissão, ao número de dispositivos interconectados ou mesmo às aplicações existentes. Em paralelo, percebemos também este avanço nos diversos segmentos da área de automação, tais como: industrial, comercial e residencial. Em uma de suas ramificações, encontram-se as redes hospitalares, que podem fazer uso de uma gama de serviços, que vão desde o simples cadastro de pacientes até uma cirurgia feita por um robô sob a supervisão de um médico especialista. No contexto dos dois universos, aparecem as aplicações em telemedicina e telessaúde, que trabalham com a transferência, em tempo real, de imagens de alta resolução, som, vídeo e dados de pacientes. Surge então um problema, visto que as redes de computadores, inicialmente criadas para a transferência de dados menos complexos, está sendo agora usada por um serviço que envolve altas taxas de transferência e apresenta requisitos em relação à qualidade do serviço (QoS) oferecido pela rede. Desta forma, este trabalho pretende fazer a análise e comparação de desempenho de uma rede quando submetida a esse tipo de aplicação, para duas situações distintas: a primeira sem o uso de políticas de QoS, e a segunda com a aplicação de tais políticas, usando como cenário para os testes, a rede da Universidade Federal do Rio Grande do Norte.

40
  • MARINALDO PINHEIRO DE SOUSA NETO
  • Caracterização de Antenas Planares com Substrato Metamaterial

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • LUIZ MARCOS GARCIA GONCALVES
  • JOABSON NOGUEIRA DE CARVALHO
  • JOSE PATROCINIO DA SILVA
  • Data: Nov 25, 2011


  • Show Abstract
  • Esta dissertação de Mestrado apresenta uma análise teórica e numérico-computacional, das características ressonantes de uma antena de microfita com patch retangular utilizando substrato metamaterial. A análise utiliza o formalismo de onda completa através da aplicação do método da Linha de Transmissão Transversa - LTT, no domínio da transformada de Fourier. É realizado um estudo acerca da teoria dos metamateriais com o intuito de obter seus parâmetros construtivos, sendo caracterizados através de tensores permissividade e permeabilidade. As equações gerais para os campos eletromagnéticos da antena são desenvolvidas aplicando o método da Linha de Transmissão Transversa - LTT. A aplicação das condições de contorno adequadas à estrutura permite determinar as funções diádicas de Green, relacionando os componentes da densidade de corrente no patch com os componentes tangenciais do campo elétrico. O método de Galerkin é então usado para obter a equação matricial, cuja solução não trivial fornece a freqüência de ressonância da antena. A partir da modelagem foram desenvolvidos programas computacionais, para obter resultados da freqüência de ressonância em diferentes configurações de antenas e substratos, além da perda de retorno destas antenas.

     

     

41
  • EMANUEL GUERRA DE BARROS FILHO
  • Controle Inteligente Aplicado a uma Mesa de Coordenadas de Dois Graus de Liberdade

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • SAULO DE TARSO MARQUES BEZERRA
  • Data: Dec 9, 2011


  • Show Abstract
  • Apresenta-se, neste trabalho, o projeto e a construção de uma mesa de coordenadas de dois graus de liberdade, bem como o desenvolvimento de um sistema fuzzy para o controle de posição e trajetória dessa mesa. A mesa é composta de duas bases que se movimentam perpendicularmente entre si, no plano horizontal, e sao acionadas por dois motores de corrente contínua. As posições das bases sao detectadas por dois sensores de posição acoplados aos eixos dos motores. Uma placa de aquisição de dados realiza a interface entre um computador portátil e a planta. O algoritimo do sistema fuzzy foi implementado no ambiente de programação LabVIEW®,  que processa os sinais proveniente dos sensores e determina as variáveis de controle que acionam os motores. Resultados experimentais utilizando sinais de referência de posição (sinais tipo degrau) e sinais de referencia de trajetórias retilíneas e circulares sao apresentados para mostrar o comportamento dinâmico do sistema fuzzy.

42
  • LEONARDO RENE DOS SANTOS CAMPOS
  • Roteamento em Redes Sensores Sem Fio com Base em Aprendizagem por Reforço

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • GUILHERME DE ALENCAR BARRETO
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Dec 19, 2011


  • Show Abstract
  • A utilização das redes de sensores e atuadores sem fio nas plantas das indústrias vem
    crescendo nos últimos anos, trazendo vários benefícios em relação aos sistemas cabeados,
    como flexibilidade na instalação e manutenção da rede. Tais redes consistem basicamente
    de um número possivelmente grande de dispositivos sensores e atuadores pequenos e
    autônomos que possuem capacidade de comunicação sem fio. Os dados coletados pelos
    sensores são enviados—seja diretamente ou passando através de nós intermediários pela
    rede — até uma estação-base conhecida como nó sink. O roteamento nesse ambiente
    é uma questão essencial já que está intimamente ligado à eficiência energética e consequentemente
    ao tempo de vida da rede. Este trabalho investiga a aplicação de uma técnica
    de roteamento baseado no algoritmo Q-Learning de Aprendizado por Reforço a uma rede
    de sensores sem fio através de simulações no ambiente ns-2. Diversas métricas como
    consumo de energia, taxa de pacotes entregues com sucesso e atrasos são utilizadas para
    validar a proposta comparando-a com outras soluções existentes na literatura.

43
  • JOSE HAROLDO CAVALCANTE DE MORAIS
  • Projeto de Antenas de Microfita Banda Larga para Aplicação em Dispositivos Móveis e/ou Portáteis

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • JEFFERSON COSTA E SILVA
  • Data: Dec 19, 2011


  • Show Abstract
  • Este trabalho apresenta resultados simulados e medidos de antenas planares de microfita banda larga para aplicações em notebooks. Para isso, é utilizado o programa computacional comercial Ansoft Designer HFSS. São consideradas técnicas de miniaturização e de melhoria de largura de banda, para antenas de microfita sobre uma camada dielétrica isotrópica. Serão analisadas diferentes geometrias, para as principais aplicações de sistemas de radiofrequência de notebooks. Por fim, será mostrado como melhorar algumas deficiências de antenas planares de microfita, para se obter as dimensões físicas e respostas desejadas.

44
  • LEONARDO RODRIGUES DE LIMA TEIXEIRA
  • Uma Abordagem Indireta para o Controlador em Modo Dual Adaptativo Robusto

  • Advisor : JOSENALDE BARBOSA DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • CAIO DORNELES CUNHA
  • JOSENALDE BARBOSA DE OLIVEIRA
  • TIAGO ROUX DE OLIVEIRA
  • Data: Dec 19, 2011


  • Show Abstract
  • Este trabalho propõe uma abordagem indireta para o Controlador em Modo Dual Adaptativo Robusto (DMARC), o qual une as características transitórias e de robustez típicas dos Sistemas a Estrutura Variável, mais especificamente o VS-MRAC, com um sinal de controle suave em regime permanente, típico dos Controladores Adaptativos convencionais, como o MRAC. O objetivo é proporcionar uma maneira mais intuitiva de realizar o projeto do controlador, baseado nos parâmetros físicos da planta, tais como: resistência, momento de inércia, capacitância, dentre outros. Adicionalmente, com a finalidade de seguir a linha evolutiva dos controladores diretos, será proposta uma versão indireta para
    o B-MRAC, o qual foi precursor na tentativa de atuar tanto como MRAC quanto como VS-MRAC, a depender de um parâmetro fixo pré-definido.

45
  • JOAO COELHO DE SOUSA FILHO
  • SENSORES E INTERFACES COM APLICAÇÕES EM MOTOR MANCAL

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ANDRES ORTIZ SALAZAR
  • JOSE ALVARO DE PAIVA
  • Data: Dec 19, 2011


  • Show Abstract
  • Relevantes pesquisas vêm sendo desenvidas em máquinas elétricas desprovidas de

    mancais ou rolamentos, também conheidas como motor mancal. Neste trabalho faz-se

    uma abordagem de um sistema que pode ser aplicado a uma máquina sem mancal enfatizado

    o projeto e implementação dos sensores e interfaces necessários ao controle de

    posicionamento do eixo do rotor, rotação e troque da máquina. Os sinais oriundos do motor

    são condicionados às entradas analógicas do DSP TMS320F2812 e utilizados como

    variáveis no programa de controle. Este trabalho tem por proposta elaborar e implementar

    um sistema envolvendo sensores e interfaces compatíveis as entradas e saídas do DSP

    TMS320F2812, para controle dá máquina, tendo como foco a modularidade e simplicidade

    de circuitos, redução das fontes de alimentação, melhoria na imunidade a ruído e

    melhor resposta em frequência acima de 10 kHz. O sistema é testado em um motor de

    indução de 2 kVA modificado para operar como motor mancal.

    Palavras-chave

    : Digital Signal Processor (DSP), Máquinas sem Mancais, Motor

46
  • TERCIO DE LIMA SILVA
  • Análise de Onda Completa de Superfície Seletiva em Frequência do Tipo Anteparo Duplo

  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • Data: Dec 21, 2011


  • Show Abstract
  • Este trabalho descreve a análise completa de um FSS do tipo anteparo duplo. A estrutura é composta por duas FSS  de camadas individuais composta por materiais dielétricos isotrópicos. A relação entre os campos espalhados e as fontes de corrente é apresentada. O procedimento analítico para obter a função diádica de Green e os campos incidentes é detalhado. O procedimento numérico para obter a densidade de corrente superficial induzida nos patches e, conseqüentemente, os campos espalhados também é apresentada. Por fim, mostramos como a transferir as impedâncias vistas pelo fontes de corrente para o topo e para a base da estrutura.

47
  • HELIO HENRIQUE CUNHA PINHEIRO
  • Sistema para Detecção e Diagnóstico de Falhas em Motores Elétricos de Indução Utilizando Lógica Fuzzy

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FILIPE DE OLIVEIRA QUINTAES
  • Data: Dec 22, 2011


  • Show Abstract
  • Os motores de indução constituem-se num dos equipamentos mais
    importantes da indústria moderna. Contudo, em muitas situações, ficam sujeitos a
    condições inadequadas como temperaturas e pressões elevadas, variações de
    carga e vibrações constantes, por exemplo. Tais condições, deixa-os mais
    susceptíveis a falhas, seja de natureza externa ou interna, indesejadas no processo
    industrial. Neste contexto, a manutenção preditiva desempenha um papel relevante,
    onde a detecção e o diagnóstico de falhas conseguidos em tempo hábil possibilita o
    aumento do tempo de uso do motor e a possibilidade de diminuição de custos,
    causados principalmente, com a parada da produção e com a manutenção corretiva
    do próprio  motor. Diante desta conjuntura, este trabalho propõe a concepção de um
    sistema que seja capaz de detectar e de diagnosticar falhas em motores de indução,
    a partir da leitura e da interpretação de diagramas fasoriais de tensão e de corrente
    de linha e da velocidade do motor, executados por um sistema inteligente baseado
    em lógica fuzzy.

48
  • CARLOS GOMES DE MOURA
  • Predição de Campo em Comunicação sem Fio

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • HUMBERTO CESAR CHAVES FERNANDES
  • IDALMIR DE SOUZA QUEIROZ JÚNIOR
  • JOSE PATROCINIO DA SILVA
  • LAERCIO MARTINS DE MENDONCA
  • Data: Dec 29, 2011


  • Show Abstract
  • Mesmo vivendo em pleno século XXI ainda encontram-se dificuldades no acesso à internet banda larga nos diversos municípios brasileiros, em decorrência do poder aquisitivo dos habitantes bem como falta de investimento do governo. A tecnologia das redes de acesso sem fio baseadas no protocolo IEEE 802.11b - também denominada de Wi–Fi, (Wireless Fidelity) Fidelidade em Comunicações sem Fio, possui larga gama de aplicações atualmente no mercado mundial comercial, nacional e internacional. No Brasil, esta tecnologia encontra-se em plena operação nas principais cidades e tem-se mostrado atrativa no que concerne aos acessos ponto–multiponto e ponto-a-ponto.

    Neste trabalho são elaborados, uma análise comparativa de predição de campo, e analisados modelos de predição das perdas de propagação,  Modelo Okumura-Hata,  Lee, Modelo de Ikegami-Walfisch, para uma rede de computadores sem fio, no bairro de Cajupiranga e no Centro, no município de Parnamirim, no Rio Grande do Norte.

    São usados equipamentos de redes sem fio do padrão 802.11b, analisador de espectro, onde os níveis de sinais são medidos, além das alturas das antenas e das distâncias em relação ao transmissor. Os dados de potência versus distância são adicionados nos gráficos gerados e comparados com os resultados obtidos.

Thesis
1
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • Análise de Estabilidade e Generalização do Controlador Adaptativo Backstepping a Estrutura Variável

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • EDVALDO ASSUNÇÃO
  • LIU HSU
  • SAMAHERNI MORAIS DIAS
  • Data: Jan 18, 2011


  • Show Abstract
  • Neste trabalho, a análise de estabilidade do Controlador Adaptativo Backstepping a Estrutura Variável (Variable Structure Adaptive Backstepping Controller, VS-ABC) para plantas lineares com grau relativo unitário será apresentada. Apesar de suas propriedades de robustez, nenhum dos trabalhos anteriores abordou a prova de estabilidade do controlador na presença de distúrbios externos, nem a sua convergência em tempo fi nito. Diferentes algoritmos são ainda propostos, chamados de VS-ABC à relé e VS-ABC compacto, onde o número de relés é signi cativamente reduzido, motivando aplicações em ambientes industriais. Outros aspectos de natureza prática, como a suavização do sinal de controle também são discutidos. Adicionalmente, o VS-ABC para plantas com grau relativo arbitrário será apresentado com base nas abordagens clássicas do controle adaptativo backstepping (modular e por funções de sintonia), resultando nas versões M/VS-ABC (Modular VS-ABC) e T/VS-ABC (Tuning Functions VS-ABC). Neste último, ao invés do uso de derivadas parciais, o controlador utiliza o diferenciador exato e robusto (Robust Exact Di erentiator, RED), garantindo apenas propriedades locais de estabilidade. Resultados práticos são incluídos de modo a corroborar os estudos teóricos.

2
  • ANDRE MACEDO SANTANA
  • Localização e Mapeamento Simultâneos de Ambientes Planos Usando Visão Monocular e Representação Híbrida do Ambiente

  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ADRIAO DUARTE DORIA NETO
  • ANNA HELENA REALI COSTA
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • PABLO JAVIER ALSINA
  • SILVIA SILVA DA COSTA BOTELHO
  • Data: Feb 11, 2011


  • Show Abstract
  • O objetivo desta tese é apresentar uma técnica de SLAM (Localização e Mapeamento Simultâneos) adequada para ambientes planos com linhas presentes no chão, de modo a permitir que o robô navegue no ambiente fundindo informações de odometria e de visão monocular. Inicialmente, é feita uma etapa de segmentação para classificar as partes da imagem em "chão" e "não-chão". Em seguida, o processador de imagem identifica linhas na parte "chão" e os parâmetros dessas linhas são mapeados para o mundo, usando uma matriz de homografia. Finalmente, as linhas identificadas são usadas como marcos no SLAM, para construir um mapa de características.
    Em paralelo, a pose corrigida do robô, a incerteza em relação à pose e a parte "não-chão" da imagem são usadas para construir uma grade de ocupação, gerando um mapa métrico com descrição dos obstáculos.
    A utilização simultânea dos dois tipos de mapa obtidos (métrico em grade e de características) dá maior autonomia ao robô, permitindo acrescentar tarefas de planejamento em simultâneo com a localização e mapeamento.

3
  • ARRHENIUS VINICIUS DA COSTA OLIVEIRA
  • Dedução de Funções de Alívio para Priorização de Variantes de Chaveamento Adequadas à Eliminação de Sobrecargas

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • UBIRATAN HOLANDA BEZERRA
  • Data: Mar 3, 2011


  • Show Abstract
  • Na operação de sistemas elétricos, eventualmente, verificam-se violações operativas, dentre as quais, é possível citar: o nível de tensão em barramentos de uma rede, o carregamento de linhas de transmissão e transformadores de potência, etc. Caso o monitoramento dessas grandezas indique possíveis problemas, é necessário aplicar procedimentos para eliminá-los ou atenuar sua intensidade. No atual contexto do setor elétrico nacional, em que as metas de qualidade e continuidade do fornecimento de energia elétrica, impostas pelo órgão regulador, são cada vez mais desafiadoras, a restrição de carga é uma solução extrema e somente deve ser utilizada como último recurso. Para evitar o corte de carga, é possível adotar medidas de controle, tais como: re-despacho de potências ativa ou reativa, ajuste de transformadores defasadores, redistribuição de carga. Essas medidas de controle estão associadas, em geral, a aumento de custos. Outra maneira de controlar eventuais restrições operacionais pode ocorrer pela mudança da topologia da rede, através de uma metodologia que ficou conhecida na literatura técnica como Chaveamentos Corretivos. A metodologia de Chaveamentos Corretivos data do final da década de 70 e consiste de uma ferramenta de controle de fluxo de carga para a operação de sistemas elétricos. Através dessa metodologia, usando como mecanismos de controle o chaveamento de linhas de transmissão, barramentos de subestações ou elementos shunt, é possível alterar o estado de uma rede elétrica, afetando a distribuição do fluxo de potência, as perdas técnicas no sistema de transmissão, o nível de curto-circuito, o nível de tensão nos diversos barramentos de um sistema, bem como a estabilidade transitória. Uma das principais vantagens desse método de controle, comparativamente aos anteriormente citados, é a economia, haja vista que sua implementação depende da operação de elementos já existentes no sistema.

                Para a aplicação da técnica de Chaveamentos Corretivos na operação de sistemas elétricos, é necessário que os cálculos sejam processados rapidamente. O cálculo de fluxo de carga é um processo não-linear e, em certos casos, pode apresentar divergência, delongando a tomada de decisão dos operadores dos centros de controle. Dessa forma, o processo de linearização da solução é uma alternativa atraente, devido à rapidez no processamento de cálculos. Inicialmente, esse processo foi desenvolvido heuristicamente através de Funções de Alívio, baseadas em experimentos de cálculo em redes reais, para avaliar a estimativa de corrente em ramos sobrecarregados a partir da abertura de barras de uma subestação, originariamente acopladas. Entretanto, para apresentar estimativas mais próximas aos resultados calculados através de um fluxo de carga exato, desenvolveram-se, analiticamente, equações que permitem avaliar tanto a abertura quanto o acoplamento de barras numa subestação. Simulações mostraram que o tempo computacional necessário para se obter uma solução através do método linear desenvolvido é cerca de dez vezes menor que o tempo para processamento de uma solução através de um fluxo de carga exato.

                Para comprovar a eficácia do método linear desenvolvido, serão apresentados testes em diversas redes elétricas. Para variantes de chaveamento promissoras, ou seja, que apresentaram estimativas com redução no carregamento dos ramos, será criada uma lista prioritária para testar tais variantes através de um fluxo de carga exato. A ordem para classificar essas variantes será baseada de forma ascendente de acordo com o mínimo distúrbio transitório causado pelo chaveamento, cuja avaliação será realizada para cada variante através do ATP - Alternative Transient Program.

     

     

4
  • CICILIA RAQUEL MAIA LEITE
  • Arquitetura Inteligente Fuzzy para Monitoramento de Sinais Vitais de Pacientes: um Estudo de Caso em UTI

    Arquitetura baseada em Técnicas de Sistemas Inteligentes para Monitoramento de Sinais Vitais
  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • HELIANA BEZERRA SOARES
  • PEDRO FERNANDES RIBEIRO NETO
  • VINICIUS PONTE MACHADO
  • Data: Jun 10, 2011


  • Show Abstract
  • A área da automação hospitalar tem sido alvo de muitas pesquisas, abordando problemas pertinentes que podem ser automatizados, como: gerenciamento e controle (prontuário eletrônico, marcação de consulta, internamento, entre outros); comunicação (rastreamento de pacientes, materiais e funcionários); desenvolvimento de equipamentos médicos, hospitalares e laboratoriais; monitoramento (pacientes, materiais e funcionários); e auxílio ao diagnóstico médico (de acordo com cada especialidade). Esta tese de doutorado apresenta a Arquitetura de um Sistema Inteligente de Monitoramento e Envio de Alertas de Pacientes (SIMAp). A sua arquitetura está baseada em técnicas de sistemas inteligentes e aplicada na automação hospitalar, mais especificamente em Unidade de Terapia Intensiva (UTI) para monitoramento de pacientes. Para o monitoramento foi desenvolvido um modelo fuzzy para auxílio ao pré-diagnóstico médico de pacientes internados em UTI e com seus sinais vitais monitorados através de um monitor cardíaco multiparamétrico. Por fim, alertas são gerados e podem ser enviados para equipe médica, caso seja encontrada alguma anormalidade no monitoramento.

5
  • ELDER ELDERVITCH CARNEIRO DE OLIVEIRA
  • Desenvolvimento de Antenas de Microfita e Antenas DRA Broadband/Ultra Wideband para Sistemas de Comunicação Sem Fio Através de Sínteses de Pós-Cerâmicos Nanoestruturados

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • JOAO BOSCO LUCENA DE OLIVEIRA
  • RONALDO DE ANDRADE MARTINS
  • LUCIANNA DA GAMA FERNANDES VIEIRA
  • MARCOS TAVARES DE MELO
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Sep 2, 2011


  • Show Abstract
  • A busca por dispositivos cada vez menores e sem perda de desempenho vem sendo cada dia mais investigada pelos pesquisadores da área envolvendo eletromagnetismo aplicado. Antenas utilizando materiais cerâmicos com uma alta constante dielétrica, sejam elas atuando como suporte do elemento patch radiante ou como sendo o próprio elemento radiante estão em evidência nas pesquisas atuais, isso devido às inúmeras vantagens que apresentam, tais como: baixo perfil, capacidade de redução de suas dimensões quando comparado a outros dispositivos, alta eficiência de radiação, adequabilidade a faixa de micro-ondas e/ou ondas milimétricas, baixo coeficiente de temperatura e baixo custo. A razão para essa alta eficiência, é que as perdas dielétricas é devido a tangente de perdas dielétricas das cerâmicas serem muito baixas quando comparado a materiais comercialmente vendidos, por exemplo, as placas de circuito impresso, tais como: fibra de vidro e fenolite. Essas características tornam dispositivos cerâmicos adequados para operar na faixa de micro-ondas. Aliando o projeto de antenas patch e/ou antenas ressoador dielétrico (DRA) a certos materiais e ao método de síntese desses pós na fabricação dos dispositivos, é possível escolher um material com uma determinada constante dielétrica no projeto de uma antena com o tamanho considerado. O objetivo desse trabalho consiste no projeto de antenas patches eantenas DRA sob síntese de pós-cerâmicos (síntese por combustão e por precursores poliméricos-método Pechini) nanoestruturados com aplicações na faixa de micro-ondas. O método convencional de mistura de óxidos também foi utilizado na obtenção de pós nanométricos para a confecção das pastilhas e ressoadores dielétricos. Em que, os dispositivos fabricados e estudados sobre materiais de alta constante dielétrica os tornam bons candidatos a terem suas dimensões reduzidas quando comparado a outros dispositivos operando na mesma faixa de frequência. As estruturas analisadas são excitadas por três diferentes técnicas: i) linha de microfita, ii) acoplamento por abertura e iii)acoplamentoindutivo.

    A eficiência dessas técnicas foram investigada experimentalmente e comparada com simulações realizadas pelo Ansoft HFSS, utilizado na análise precisa do comportamento eletromagnético dasantenas através dométodo do elementofinito (FEM). Nessa tese um estudo bibliográfico sobre teoria de antenas de microfita e antenas DRA é realizado. O mesmo estudo é realizado a respeito dos materiais e dos métodos de síntese dos pós cerâmicos que serão utilizados na fabricação das pastilhas e dos cilíndros dielétricos que comporão os dispositivos investigados. Os meios dielétricos os quais servirão de suporte na análise das antenas patch e/ou DRA serão analisados através de simulações precisas utilizando o método das diferenças finitas no domínio do tempo (FDTD) com base na permissividade elétrica relativa (εr) e tangente de perdas desses meios (tanδ).   

    Este trabalho ainda apresenta um estudo em redes neurais artificiais, evidenciando os tipos/arquitetura de redes utilizadas e suas características, bem como os algoritmos de treinamento que foram utilizados no treinamento e na modelagem de alguns parâmetros associados aos dispositivos investigados.

6
  • CHRISTIAN CESAR DE AZEVEDO
  • Controle Robusto para Filtros Ativos de Potência Paralelo

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • CURSINO BRANDÃO JACOBINA
  • MARCELO CABRAL CAVALCANTI
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Nov 4, 2011


  • Show Abstract
  • As estratégias de controle convencionais de filtros ativos de potência paralelos (Shunt Active Power f ilters - SAPF) empregam esquemas de detecção de harmônicos em tempo real, usualmente implementados com filtros digitais. Isso pode resultar em altos custos devido o aumento no número de sensores na estrutura do filtro. Além disso, esses esquemas de detecção introduzem atrasos que podem deteriorar o desempenho da compensação de harmônicos. Diferentemente dos esquemas de controle convencionais, este trabalho propõe uma nova estratégia de controle que regula indiretamente as correntes de fase da rede elétrica. As correntes de referência do sistema são geradas pelo controle de tensão do barramento CC e são baseadas no balanço de potência ativa do sistema SAPF. As correntes de referência são alinhadas com o ângulo de fase do vetor tensão da rede, que é obtido usando um PLL (Phase Locked Loop). O controle de corrente é implementado por uma estratégia de controle adaptativo por alocação de pólos, integrada com um esquema de controle com estrutura variável (VS-APPC). No VS-APPC, o princípio do modelo interno (IMP) de referência é
    usado para eliminar o erro em regime permanente das correntes de fase do sistema. Isso força as correntes de fase do sistema a serem senoidais e com baixo teor de harmônicos. Além disso, os controladores de corrente são implementados no referencial estacionário para evitar transformações nas coordenadas de referência do vetor tensão da rede. Esta estratégia de controle de corrente melhora a performance do SAPF com uma resposta transitória rápida e robusto a incertezas paramétricas. Resultados experimentais são apresentados para demonstrar a eficácia do sistema de
    controle proposto para o SAPF.

7
  • FABIANA TRISTAO DE SANTANA
  • Fundamentação Teórica e Propriedades de Aritméticas Complexas Intervalares Aplicadas em Processamento de Sinais

  • Advisor : REGIVAN HUGO NUNES SANTIAGO
  • COMMITTEE MEMBERS :
  • AARAO LYRA
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • REGIVAN HUGO NUNES SANTIAGO
  • RENATA HAX SANDER REISER
  • Data: Dec 2, 2011


  • Show Abstract
  • Nesse trabalho fizemos um estudo detalhado de algumas aritméticas que lidam com números complexos sujeitos à imprecisões, investigamos algumas propriedades que serão relevantes no desenvolvimento do trabalho e apresentamos alguns resultados à respeito dessa teoria. Estendemos o conceito de sinais e sistemas para o caso intervalar utilizando a função de representação que mapeia um número com incerteza no menor intervalo de máquina que o represente. Investigamos as principais propriedades de sinais intervalares complexos, definimos a convolução intervalar para os sinais complexos intervalares, além de apresentar um estudo sobre os sitemas intervalares complexos lineares e invariantes no tempo. Apresentamos uma fundamentação intervalar complexa para a transformada Z e para a transformada de Fourier discreta no tempo e investigamos as principais propriedades.

2010
Dissertations
1
  • ALLAN DAVID GARCIA DE ARAUJO
  • Uma Proposição para Cálculo de Mapas de Disparidades de Imagens Estéreo usando um Interpolador Neural Baseado em Funções de Base Radial

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ALLAN DE MEDEIROS MARTINS
  • ANTONIO DE PADUA DE MIRANDA HENRIQUES
  • Data: Jan 13, 2010


  • Show Abstract
  • Realizar o casamento de dois pontos em um par de imagens estéreo é um dos desafios atuais no processamento digital de imagens. As técnicas atuais de casamento estéreo possuem um alto custo computacional, não oferecendo uma solução definitiva para resolver o problema da correspondência de forma especialmente eficiente. Este trabalho irá apresentar uma proposição para otimização do cálculo do mapa de disparidades, introduzindo um casamento espaçado e uma etapa de pós-processamento para reconstrução dessas superfícies através da interpolação dos dados não calculados utilizando uma rede neural artificial de função de base radial (RBF).

2
  • ADERSON JAMIER SANTOS REIS
  • Reconhecimento de Padrões de Falhas em Motores Trifásicos Utilizando Redes Neurais

  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • JOSE ALVARO DE PAIVA
  • JOSSANA MARIA DE SOUZA FERREIRA
  • Data: Feb 19, 2010


  • Show Abstract
  • Este trabalho apresenta um sistema de diagnóstico de falhas (rotor, estator e contaminação) do motor de indução trifásico através dos parâmetros do circuito equivalente e utilizando técnicas de reconhecimento de padrões. A tecnologia de detecção de falhas em motores está evoluindo e tornando cada vez mais importante na área de máquinas elétricas. As redes neurais possuem a habilidade de classificar relações não lineares entre sinais através da identificação de padrões dos sinais relacionados. São realizados simulações do motor de indução através do programa Matlab® \& Simulink® e produzido alguns tipos de falhas no conjunto a partir de modificações nos parâmetros do circuito equivalente. É implementado um sistema com múltiplos classificadores neurais para receber estes resultados e, após o treinamento, realizar a identificação dos padrões de falhas.

3
  • ALAN PAULO OLIVEIRA DA SILVA
  • Uma Implementação da Análise de Componentes Independentes em Plataforma de Hardware Reconfigurável

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • DANNIEL CAVALCANTE LOPES
  • GLAUCIO BEZERRA BRANDAO
  • Data: Feb 19, 2010


  • Show Abstract
  • A Separação Cega Fontes (BSS) refere-se ao problema de estimar sinais originais a partir de misturas lineares observadas sem nenhum tipo de conhecimento acerca das fontes ou do processo de mistura. A Análise de Componentes Independentes (ICA) é uma técnica aplicada principalmente ao problema do BSS e dentre os algorítmos que implementam essa técnica, o FastICA é um algorítmo iterativo de alto desempenho e de baixo custo computacional que utiliza medidas de não-gaussianidade baseadas em estatística de alta ordem para estimar as fontes originais. O grande número de aplicações onde ICA se mostra útil reflete a necessidade da implementação dessa técnica em hardware e o paralelismo natural do FastICA favorece a implementação desse algorítmo em plataforma de hardware digital.
    Este trabalho propõe a implementação do FastICA em uma plataforma de hardware reconfigurável para a viabilização de sua utilização em problemas de separação cega de fontes, mais especificamente em um protótipo de hardware embarcado em uma placa Fiel Programmable Gate Array (FPGA) para a monitoração de leitos em ambientes hospitalares. As implementações serão realizadas através de modelos em Simulink e a sintetização dos mesmos será feita com o auxílio do software DSP Builder da Altera Corporation.

4
  • PATRICIA ALOISE COUTO
  • Estudo da Qualidade de Serviço de uma Aplicação VoIP em Ambientes Wireless com Handoff

  • Advisor : JOAO BATISTA BEZERRA
  • COMMITTEE MEMBERS :
  • JOAO BATISTA BEZERRA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • SERGIO VIANNA FIALHO
  • Data: Feb 19, 2010


  • Show Abstract
  • Esse trabalho tem como objetivo analisar o desempenho de uma aplicação Voz sobre IP – VoIP  quando submetida ao handoff  em rede 802.11b, tomando como estudo de caso, dois ambientes da rede sem fio da Universidade Federal do Rio Grande do Norte – UFRN, denominados de indoor e outdoor. A comunicação VoWiFi  é realizada pela aplicação Ekiga entre uma estação em mobilidade na rede 802.11b e outra estação fixa em rede FastEthernet. Nos experimentos é considerado o efeito da carga da aplicação VoIP, com e sem concorrência de tráfego, tanto no ambiente WiFi Indoor quanto no ambiente WiFi outdoor. Essa concorrência de tráfego é “provocada” na rede 802.11b através da ferramenta Iperf. Já os resultados das métricas de desempenho de qualidade de serviço, como o jitter, a vazão e a perda de pacotes, são analisadas mediante o analisador de desempenho, Wimanager e os Scripts em Bash Shell.  Já o atraso foi obtido através de estimativas baseadas no cálculo do jitter. São realizados 295 (duzentos e noventa e cinco) experimentos, porém só foram utilizados 48 (quarenta e oito) experimentos. Nesses 48 experimentos é evidenciada a ocorrência de “queda” da conexão no momento da migração de uma “célula” para outra, sendo todas perceptíveis ao usuário. Essa descontinuidade das conexões no momento de handoff, utilizando o padrão 802.11b também foram evidenciados por alguns trabalhos da literatura, como a Transmissão de Voz sobre Redes IEEE 802.11 e o trabalho sobre a Avaliação de Desempenho de uma Aplicação VoIP, produzidos respectivamente por Conceição et al. (2006) e Barbosa et al. (2006).

5
  • MARCIO VALERIO DE ARAUJO
  • Desenvolvimento de Uma Órtese Ativa Para os Membros Inferiores Com Sistema Eletrônico Embarcado

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • PABLO JAVIER ALSINA
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ADRIANO ALMEIDA GONCALVES SIQUEIRA
  • Data: Feb 26, 2010


  • Show Abstract
  • Este trabalho tem como objetivo apresentar o desenvolvimento de um protótipo de órtese ativa inteligente para membros inferiores com um sistema eletrônico embarcado. A órtese proposta é um dispositivo ortopédico com o principal objetivo de proporcionar a capacidade de caminhar para pessoas com parcial ou total perda dos movimentos nos membros inferiores. A fim de determinar a cinemática, dinámica e as características mecânicas do protótipo, foi analisada a biomecânica do corpo humano. A órtese foi projetada para reproduzir alguns dos movimentos da marcha humana como andar em linha reta, sentar, levantar, subir e descer degraus. O acionamento das articulações da órtese
    é realizado por motores CC equipados com caixa de redução, cujo objetivo é reduzir a velocidade de rotação e aumentar o torque, gerando assim, movimentos suaves. O sistema eletrônico embarcado é composto por duas placas controladoras de motores com dois canais que se comunicam com um computador embarcado, sensores de posição e de fim de curso. O movimento de marcha da órtese é controlado por comandos de alto nível fornecidos através da interface homem-máquina do sistema. O sistema eletrônico
    embarcado é utilizado para interpretar os comandos de alto nível, gerar as referências angulares para as juntas da órtese, acionar e controlar os atuadores da órtese de forma a executar os movimentos desejados pelo usuário.

6
  • JANIO MENDONCA JUNIOR
  • Um sistema para simular o comportamento de bancos trifásicos de reguladores de tensão usados em  sistemas de distribuição de energia elétrica

  • Advisor : JOSE ALBERTO NICOLAU DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Mar 5, 2010


  • Show Abstract
  • A crescente concorrência nos serviços de distribuição de energia elétrica de boa qualidade obriga as concessionárias a investirem em projetos que garantam a sua qualidade. Manter níveis de tensão em padrões aceitáveis no ponto de entrega da energia elétrica ao consumidor é um dos principais problemas enfrentados. A utilização de reguladores de tensão torna-se uma forma viável para garantir a qualidade do serviço na entrega do produto (energia elétrica), no entanto, a especificação de seus ajustes não se constitue em tarefa simples, principalmente quando se tem grande variação de carregamentos, inclusive, desequilíbrios. Com base nos problemas expostos na utilização de reguladores de tensão, foi desenvolvido um sistema para simular o comportamento de bancos trifásicos de reguladores de tensão usados em sistemas de distribuição de energia elétrica. Tal simulação será de grande valor para visualização do comportamento de bancos trifásicos de reguladores de tensão, antes de sua instalação na rede de distribuição, para definição de parâmetros de regulação e restrições de regulação, para visualização de valores de ajuste de regulação e variações de tensão. Uma característica importante deste simulador é fato deste se comunicar com um programa TOpReDE (Técnicas de otimização para redes de distribuição de energia elétrica), com intuito de comparar e validar resultados através da geração de gráficos, a partir do Matlab®. Nesta implementação foram utilizados os blocos funcionais do Matlab® /Simulink em conjunto com a biblioteca da Altera®, chamada DSP builder, ambiente no qual serão feitas simulações e testes do sistema de regulação de tensão.

7
  • HUMBERTO ARAUJO DA SILVA
  • Controlador Preditivo Generalizado Multi-Modelo para Controle de Pressão Arterial

  • Advisor : ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JULIO ELIAS NORMEY-RICO
  • Data: Mar 19, 2010


  • Show Abstract
  • Em muitos procedimentos cirúrgicos existe a necessidade de realizar o controle da pressão arterial para, com isto, preservar a saúde do paciente. Para diminuir as chances de uma complicação, é necessário reduzir a pressão arterial o mais rápido possível. A infusão contínua de drogas vasodilatadoras, como o nitroprussiato de sódio (NPS), reduz rapidamente a pressão arterial na maioria dos pacientes. Porém, cada paciente tem uma sensibilidade diferente a infusão do NPS, o que faz com que os parâmetros e os atrasos do sistema sejam desconhecidos a priori. Além disso, os parâmetros de uma função de transferência associados à um paciente particular são variantes no tempo. Desta forma, o objetivo do trabalho consiste em desenvolver uma metodologia capaz de controlar de forma automática a pressão arterial na presença de incertezas de parâmetros e de grandes atrasos. Para isto foi desenvolvida uma metodologia multi-modelo, onde para cada modelo existe um Controlador Preditivo especificamente sintonizado, e um mecanismo adaptativo decide qual controlador deve ser o dominante para uma determinada planta.

8
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • Sistema Híbrido de Inferência Baseado em Análise de Componentes Principais e Redes Neurais Artificiais Aplicado à Plantas de Processamento de Gás Natural

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • VICENTE DELGADO MOREIRA
  • Data: Mar 19, 2010


  • Show Abstract
  • Nos dias atuais, onde a concorrência de mercado exige produtos de melhor qualidade e a busca constante pela redução de custos e pelo melhor aproveitamento das matérias primas, a utilização de estratégias de controle mais eficientes torna-se fundamental. Nas Unidade de Processamento de Gás Natural (UPGNs), assim como na maioria dos processos químicos, o controle de qualidade é realizado a partir da composição de seus produtos. Entretanto, a análise de composições químicas, mesmo quando realizada por instrumentos como os cromatógrafos a gás, apresenta longos intervalos de medição. Esse fato acaba por dificultar a elaboração de estratégias de controle que proporcionem um melhor rendimento do processo.
    O principal produto econômico de uma UPGN é o GLP (Gás Liquefeito de Petróleo). Outros produtos comumente obtidos nessas unidades são a gasolina natural e o gás residual. O GLP é formado idealmente por propano e butano, entretanto, na prática, apresenta em sua composição contaminantes, tais como o etano e o pentano. Neste trabalho é proposto um sistema de inferência utilizando redes neurais para estimar as frações molares de etano e pentano no GLP e a fração molar de propano no gás residual. O objetivo é estimar essas variáveis a cada minuto com uma única rede neural de múltiplas camadas, permitindo a aplicação de técnicas de controle inferencial visando a controlar a qualidade do GLP e reduzir a perda de propano no processo.
    No desenvolvimento deste trabalho, é utilizada uma UPGN simulada no software HYSYS R, sendo formada pelas colunas de destilação deetanizadora e debutanizadora. A inferência é realizada a partir das variáveis de processo dos controladores PIDs presentes na instrumentação das colunas citadas. Com o intuito de reduzir a complexidade da rede neural de inferência, é utilizada a técnica estatística de análise de componentes principais (ACP) para diminuir o número de entradas da rede, tem-se, portanto, um sistema híbrido de inferência. Também é proposta neste trabalho, uma estratégia simples para a correção em tempo real do sistema de inferência, tendo como base as medições dos possíveis cromatógrafos de linha presentes no processo em estudo.

9
  • ERICO CADINELI BRAZ
  • Técnicas de Controle Adaptativo Robusto aplicadas a Filtro Ativos de Potência em Paralelo

  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANDRES ORTIZ SALAZAR
  • ISAAC SOARES DE FREITAS
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Mar 26, 2010


  • Show Abstract
  • Neste trabalho, é investigado o uso de uma técnica de controle adaptativo robusto para incrementar a eficiência na compensação de harmônicos em filtro ativo de potência paralelo trifásico (FAPPT). A técnica de controle proposta é aplicada às malhas de controle de corrente e de tensão do filtro. Ela é baseada na combinação das técnicas de controle adaptativo por posicionamento de pólos e de estrutura variável. Esta técnica de controle, aplicada ao FAPPT, minimiza o conteúdo harmônico das correntes de fase da fonte primária. As vantagens do método proposto sobre os convencionais são menor taxa de distorção harmônica, maior flexibilidade, capacidade de adaptação e robustez para o sistema. Além disso, a técnica de controle proposta aumenta a eficiência do filtro ativo e melhora o desempenho transitório. A validação da técnica proposta foi verificada inicialmente através de um programa de simulação implementado em linguagem C++ e em seguida foram obtidos resultados experimentais usando um protótipo de um filtro ativo trifásico de 1 kVA.

10
  • RAFAELA VILELA FRANCA
  • Um Estimador de Estado Trifásico para Sistemas de Distribuição com base no Método da Soma de Potências

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Mar 26, 2010


  • Show Abstract
  • Uma avaliação em tempo real da segurança do sistema vem se tornando uma prática essencial para a maioria das concessionárias de energia elétrica. Essa avaliação se faz a partir da monitorização das condições dos sistemas elétricos e do controle da sua operação. Essas tarefas são realizadas nos modernos centros de controle dos sistemas. A Estimação de Estados é a ferramenta mais adequada para realizar uma avaliação das condições operativas de um sistema em tempo real, e o seu desempenho depende da disponibilidade de informações confiáveis sobre o ponto atual de operação. Com esse objetivo, o trabalho desenvolvido trata de um novo modelo de estimador de estado para sistemas de distribuição, baseado no algoritmo do fluxo de carga soma de potências. O intuito deste trabaho foi de desenvolver uma formulação matemática trifásica para todos os componentes que compõe o sistema de potência. A abordagem da aproximação dos mínimos quadrados ponderados é utilizada para estimar os estados do sistema e será discutida ao longo deste trabalho.

11
  • VINICIUS SAMUEL VALERIO DE SOUZA
  • Modelagem aplicada à análise de desempenho do Provedor de Serviços de uma rede de automação hospitalar IEEE 802.3/PM-AH de tempo real

  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • GLAUCIO BEZERRA BRANDAO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: May 7, 2010


  • Show Abstract
  • Com a incorporação de conceitos da automação industrial na área médica, surge a necessidade de estabelecer mecanismos que permitam a comunicação entre os dispositivos biomédicos de maneira segura e eficiente. Dentre as soluções para esse problema tem-se o PM-AH (Protocolo Multiciclos para Automação Hospitalar) que estabelece uma rede segmentada por leitos e coordenada por um elemento chamado Provedor de Serviços. O objetivo desse trabalho é modelar esse Provedor de Serviços e efetuar análises de desempenho sobre as tarefas realizadas pelo mesmo no estabelecimento e manutenção da rede hospitalar.

12
  • GUILHERME LEAL SANTOS
  • Localização de Robôs Móveis Autônomos Utilizando Fusão Sensorial de Odometria e Visão Monocular

  • Advisor : PABLO JAVIER ALSINA
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ANFRANSERAI MORAIS DIAS
  • PABLO JAVIER ALSINA
  • Data: May 7, 2010


  • Show Abstract
  • O desenvolvimento e aperfeiçoamento de técnicas que façam simultaneamente o mapeamento e a localização (Simultaneous Localization and Mapping - SLAM) de um robô móvel autônomo e a criação de mapas locais 3-D, a partir de uma sequência de imagens, é bastante estudada no meio científico. A principal razão é a acessibilidade, porque o uso de um sistema de visão é uma alternativa barata em relação ao uso de outros tipos de sensores, como sonar, sensor infravermelho, telêmetro laser. A captura de imagens pode ser realizada por uma simples webcam. Além do baixo custo, a quantidade de dados fornecidos por uma sequência de imagens é grande.
    Neste trabalho é apresentado uma técnica de SLAM visual monocular, que utiliza características encontradas em uma sequência de imagens através do descritor SURF (Speeded Up Robust Features) para determinar quais características podem ser utilizadas como marcas. Para iniciar o mapeamento e localização, é necessário primeiro determinar a posição das marcas presentes no ambiente. Para isso, tem-se disponível apenas as coordenadas (u,v) das características detectadas na imagem e os parâmetros intrínsecos e extrínsecos da câmera. É possível determinar a posição das marcas somente com a disponibilidade da profundidade.
    Os testes mostraram que durante o percurso, o robô móvel detecta a presença de ca-racterísticas nas imagens e, através de uma técnica proposta para inicialização atrasada de marcas, adiciona centenas de novas marcas ao vetor de estados do filtro de Kalman estendido (FKE) após estimar a profundidade das características. Com a posição estimada das marcas, foi possível estimar a posição atualizada do robô a cada passo; obtendo resultados satisfatórios que comprovam a eficiência do sistema de SLAM visual monocular proposto neste trabalho.

13
  • MARCOS VINICIUS MILFONT DE AGUIAR
  • Proposta de um Compensador de Reativos Aplicado a um Gerador de Indução Utilizando Técnicas Digitais de Controle digital

  • Advisor : CAIO DORNELES CUNHA
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • CAIO DORNELES CUNHA
  • JOSE ALVARO DE PAIVA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • Data: Jun 4, 2010


  • Show Abstract
  • Neste trabalho é apresentada uma proposta para a compensação de reativos para motores de indução, em particular para aproveitamento na geração eólica. Para tanto, foi desenvolvida uma estrutura experimental composta de um motor CC, o qual simulará a propulsão eólica e um motor de indução que será utilizado como gerador de indução, um banco de capacitores em configuração delta/série, um retificador a Insulated Gate Bipolar Transistor (IGBT) controlado por pulsos PWM’s e uma carga resistiva composta de lâmpadas. Para o funcionamento do motor de indução como gerador foi desenvolvido um sistema de comando, o qual é responsável por realizar a transferência da energia armazenada nos capacitores para a bobina do estator do motor.
    Para a realização do controle do retificador, que funcionará como compensador de reativos, foi confeccionado um programa na linguagem C++ usando um controlador Proporcional Integral (PI) para controlar o nível de tensão do barramento CC e para atingir o fator de potência unitário utilizou-se dois outros PI’s para controle das correntes em referencial estacionário. Para a modelagem do compensador foi utilizada a transformada de Clarke e Park. A malha de controle em tempo real utilizou controle vetorial a fim de diminuir as perdas por chaveamento real e foi projetada utilizando um Processador de Sinais Digitais (DSP), o qual é composto de todas as ferramentas necessárias para o perfeito controle do sistema implementado. A avaliação do desempenho do sistema foi realizada com uma carga de 400W.

14
  • LEONARDO MARTINS CAETANO
  • Aplicações de Arranjos de Antenas de Microfita com Patch supercondutor

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • CLODOMIRO ALVES JUNIOR
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Jun 11, 2010


  • Show Abstract
  • Este trabalho tem como objetivo principal o estudo dos arranjos de fase (observados em sua maioria nos diagramas de radiação) em antenas de microfita com patch retangular supercondutor. Será apresentado um estudo das principais teorias que explicam com clareza a questão da supercondutividade. As teorias BCS, Equações de London e modelo dos Dois Fluidos serão as teorias que darão suporte a aplicação dos supercondutores nas antenas microfita. Os arranjos de fase serão analisados em configurações lineares e planares de suas antenas. Serão obtidos os fatores de arranjos para tais configurações e os critérios da fase e do espaçamento entre os elementos que compõe o arranjo, ao qual serão examinados com o objetivo de minimizar as perdas devido aos lóbulos secundários. A antena com patch retangular, constituído de material supercondutor é analisada através do método da Linha de Transmissão Transversa (LTT), aplicado no domínio da transformada de Fourier (FTD). O LTT é um método de onda completa, que tem como regra a obtenção dos campos eletromagnéticos em termos das componentes transversais à estrutura. A inclusão do patch supercondutor é feita utilizando-se a condição de contorno complexa resistiva. São obtidos resultados da freqüência de ressonância em função dos parâmetros da antena; diagramas de radiação do Plano-E e Plano-H para os arranjos de fase de antenas nas configurações lineares e planares para diferentes valores da fase e espaçamento entre os elementos.

15
  • VALDEZ ARAGAO DE ALMEIDA FILHO
  • Arranjos Log-Períodicos Compactos em Microfita com Elementos Fractais de Koch

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • GLAUCO FONTGALLAND
  • PAULO HENRIQUE DA FONSECA SILVA
  • RONALDO DE ANDRADE MARTINS
  • Data: Jun 14, 2010


  • Show Abstract
  • Este trabalho tem como objetivo apresentar como a aplicação de contornos fractais aos elementos de um arranjo log-periódico se torna uma alternativa bastante interessante quando se deseja reduzir as dimensões do arranjo. Foram propostos dois tipos de arranjos log-periódicos: um com alimentação por linha de microfita e outro com alimentação por acoplamento eletromagnético. Aos elementos desses arranjos foram aplicados contornos fractais de Koch, em dois níveis. Com a finalidade de validar os resultados obtidos foram construídos protótipos, que foram medidos em um analisador de rede vetorial e simulados em software para comparação. Os resultados mostraram reduções de 60% nas dimensões dos arranjos, para ambos os tipos. Através da análise dos gráficos da perda de retorno, pôde-se observar que a aplicação dos contornos fractais fez com que aparecessem diferentes frequências de ressonância nos arranjos. O arranjo com alimentação por acoplamento eletromagnético apresentou, após aplicação dos contornos fractais, diagramas de radiação com formas mais suaves do que o arranjo com alimentação por linha de microfita.

16
  • ALINE FARIAS GOMES
  • ENUMERAÇÃO DO ESPECTRO DE DISTÂNCIAS DE ESQUEMAS DE MODULAÇÃO CODIFICADA EM TRELIÇA EMPREGANDO CODIFICAÇÃO TURBO

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • HUMBERTO CESAR CHAVES FERNANDES
  • SUZETE ELIDA NOBREGA CORREIA
  • Data: Jun 14, 2010


  • Show Abstract
  • Neste trabalho é feita a análise de desempenho de esquemas de transmissão TTCM, utilizando uma técnica de limitante expurgado da união. Esta técnica é baseada na enumeração do espectro de distâncias deste esquema turbo, utilizando uma técnica proposta de perfuração, onde a técnica de perfuração é empregada a nível de símbolo e não de bit como na maioria dos trabalhos da literatura. Neste trabalho também são apresentados dois algoritmos matriciais de redução de estados do codificador bem como do cálculo da função de transferência deste. Os resultados deste trabalho são apresentados em forma de comparações dos limitantes obtidos com a técnica proposta, com alguns códigos turbo da literatura.

17
  • BRUNA ALICE TAVEIRA DE LIMA
  • Antenas Monopolo Planar com Patch em Anel Circular para Sistemas UWB

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • GLAUCO FONTGALLAND
  • LAERCIO MARTINS DE MENDONCA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Jun 14, 2010


  • Show Abstract
  • As antenas de microfita são largamente utilizadas nos sistemas de comunicação sem fio devido às suas características de baixo custo, peso e complexidade de projeção, além de sua versatilidade, o que faz com que estes dispositivos venham sendo amplamente estudados. Os sistemas UWB surgiram como uma alternativa às comunicações sem fio de curtas distâncias por oferecerem maior capacidade que outros sistemas com a mesma finalidade, a exemplo do Bluetooth e RFID, bem como menor distorção por multipercurso. Aliando as vantagens das antenas de microfita às características do UWB, é possível desenvolver dispositivos cada vez menores e com geometrias diversificadas para operar satisfatoriamente nesses sistemas. Este trabalho tem como objetivo propor alternativas de antenas de microfita para operar em sistemas UWB, na faixa entre 3,1 e 10,6 GHz, com patch  em anel circular. Como alternativas, são empregadas e analisadas algumas técnicas para aumentar a largura de banda das antenas propostas, sendo estas técnicas a inserção de elementos parasitas e de uma fenda retangular no plano terra deslocado. Para isto, são apresentados temas fundamentais como os princípios básicos dos sistemas UWB, a teoria fundamental de antenas e antenas de microfita. São apresentadas as simulações e medições realizadas dos protótipos construídos, bem como uma análise de parâmetros como a largura de banda e o diagrama de radiação.

18
  • PAULO VITOR SILVA
  • Implementação Experimental de Filtro Ativo Paralelo de Potência com Aplicação a Gerador de Indução Trifásico
  • Advisor : RICARDO FERREIRA PINHEIRO
  • COMMITTEE MEMBERS :
  • RICARDO FERREIRA PINHEIRO
  • ANDRES ORTIZ SALAZAR
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • FERNANDO LUIZ MARCELO ANTUNES
  • Data: Jun 28, 2010


  • Show Abstract
  • Este trabalho descreve a montagem de um filtro ativo paralelo de potência para viabilizar a produção de energia elétrica através de um gerador de indução trifásico. O sistema foi desenvolvido para o aproveitamento prioritário de fontes de energias renováveis como pch’s e centrais eólicas. A estratégia de controle do filtro ativo envolveu a implementação de um chaveamento PWM digital, tendo sido realizada a comparação de duas técnicas para obtenção das correntes de referência. A primeira técnica se baseia no método referencial síncrono dq e a segunda se baseia nas potências instantâneas desenvolvidas por Akagi et al. A comparação é realizada via simulação e via resultados experimentais. Para obtenção dos resultados experimentais, foi montada uma bancada experimental e o controle e comunicações necessárias ao estágio supervisório foram implementadas via DSP - TMS320F2812

19
  • CARLOS ALBERTO DE ALBUQUERQUE SILVA
  • CONTRIBUIÇÃO PARA O EMBARQUE DE UMA REDE NEURAL ARTIFICIAL EM FIELD PROGRAMMABLE GATE ARRAY (FPGA)

     

    CONTRIBUIÇÃO PARA O EMBARQUE DE UMA REDE NEURAL          ARTIFICIAL EM Field Programmable Gate Array (FPGA)
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DANNIEL CAVALCANTE LOPES
  • JORGE DANTAS DE MELO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • Data: Jun 30, 2010


  • Show Abstract
  • O presente trabalho se propõe a apresenta os desafios e soluções deparadas durante o fluxo de projeto de desenvolvimento de uma arquitetura de Redes Neurais Artificiais (RNA) em hardware, por meio de um dispositivo programável do tipo Field Programmable Gate Arrays (FPGA). Para esta aplicação convencionou-se empregar duas abordagens para o desenvolvimento, uma em software que utiliza o MATLAB® para treinamento e validação da rede e outra em hardware, que parte da descrição em VHDL de um neurônio artificial capaz de lidar com os dados de entrada, pesos sinápticos e bias através da aritmética em ponto fixo. A arquitetura em hardware da uma RNA pode ser estruturada, de acordo com a necessidade de resolução de cada problema proposto, replicando o neurônio artificial e organizando-os em camadas, a fim de processarem a saída desejada da rede.

20
  • HUMBERTO DIONISIO DE ANDRADE
  • RESSOADOR RETANGULAR DE FENDA COM QUATRO CAMADAS FOTÔNICAS

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • ELIALDO CHIBERIO DA SILVA
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Data: Jun 30, 2010


  • Show Abstract
  • Recentemente as antenas planares tem despertado interesses devido as suas características assim como pelas vantagens que oferecem quando comparadas com os demais tipos de antenas.

    Na área de comunicações móveis a necessidade de antenas desse tipo, tem se tornado cada vez mais devido ao intenso desenvolvimento, que necessita de antenas que operem em multifreqüência e em banda larga. As antenas de microfita apresentam largura de banda estreita devido as perdas no dielétrico geradas pela irradiação. Outra limitação é a degradação do diagrama de irradiação devido a geração de ondas de superfície no substrato. Algumas técnicas estão sendo desenvolvidas para minimizar esta limitação de banda, como é o caso do estudo de materiais do tipo PBG – Photonic Band Gap, para compor o material dielétrico.

    As análises desenvolvidas neste trabalho foram realizadas com utilização do método LTT – Linha de Transmissão Transversa, no domínio da Transformada de Fourier que utiliza uma componente de propagação na direção y (transerva à direção real de propagação z), tratando assim as equações gerais dos campos elétricos e magnéticos em função de e .

    Este trabalho tem como objetivo principal a aplicação do método LTT às estruturas ressoadoras de linha de fenda com quatro camadas de material fotônico PBG, para a obtenção da freqüência de ressonância complexa e a eficiência dessa estrutura.

    A teoria PBG será aplicada para a obtenção da permissividade relativa para as polarizações s e p dos substratos compostos de material fotônico.

    Resultados numérico-computacionais em forma de gráfico em duas  dimensões para todas as análises realizadas são apresentados, para as estruturas propostas que tem como substratos materiais fotônicos.  

    São apresentadas conclusões e sugestões para a continuidade deste trabalho.

21
  • HUGO MICHEL CAMARA DE AZEVEDO MAIA
  • ANTENAS DE MICROFITA COM PATCH SUPERCONDUTOR A 212 K

  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • ELIALDO CHIBERIO DA SILVA
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • LEONARDO MARTINS CAETANO
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Data: Jul 9, 2010


  • Show Abstract
  • Este trabalho tem como objetivo principal o estudo da aplicação de antenas de microfita com patch supercondutor e uso dos arranjos de fase linear e planar. Será apresentado um estudo das principais teorias que explicam com clareza a supercondutividade. As teorias BCS, Equações de London e modelo dos Dois Fluidos serão as teorias que darão suporte a aplicação dos supercondutores nas antenas de microfita. Os arranjos de fase serão analisados em configurações lineares e planares de suas antenas. Serão obtidos os fatores de arranjos para tais configurações e os critérios da fase e do espaçamento entre os elementos que compõe o arranjo, ao qual serão examinados com o objetivo de minimizar as perdas devido aos lóbulos secundários. A antena com patch retangular, constituído de material supercondutor é analisada através do método da Linha de Transmissão Transversa (LTT), aplicado no domínio da transformada de Fourier (FTD). O LTT é um método de onda completa, que tem como regra a obtenção dos campos eletromagnéticos em termos das componentes transversais à estrutura. A inclusão do patch supercondutor é feita utilizando-se a condição de contorno complexa resistiva. São obtidos resultados da freqüência de ressonância em função dos parâmetros da antena; diagramas de radiação do Plano-E e Plano-H para os arranjos de fase de antenas nas configurações lineares e planares para diferentes valores da fase e espaçamento entre os elementos.Comunicações sem fio, algoritmos genéticos, otimização, modelos de predição de perda de propagação

22
  • GUSTAVO ARAÚJO CAVALCANTE
  • Otimização de Modelos de Predição da Perda de Propagação Aplicáveis em 3,5 GHz Utilizando Algoritmos Genéticos

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • RONALDO DE ANDRADE MARTINS
  • ALFREDO GOMES NETO
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • Data: Jul 9, 2010


  • Show Abstract
  • O setor de telecomunicações tem passado por recentes transformações, devido ao aumento da busca por acesso a serviços digitais de transmissão de dados, vídeo e multimídia, especialmente, por meios das redes de telefonia móvel. Recentemente no Brasil as operadoras de telefonia móvel vêm atualizando suas redes para sistemas de terceira geração (3G) proporcionando aos usuários serviços em banda larga como vídeo conferencia, Internet, tv digital entre outros. Essas novas redes que proporcionam mobilidade e elevadas taxas de transmissão tem permitido o desenvolvimento de novos conceitos de mercado. Atualmente o mercado está voltado para a expansão da tecnologia WiMAX, que vêm ganhando cada vez mais o mercado das comunicações móveis de voz e de dados. No Brasil o interesse comercial para esta tecnologia aparece com a primeira outorga de licenças na faixa de 3,5 GHz. Em fevereiro de 2003 a ANATEL realizou a licitação 003/2002/SPV-ANATEL, onde ofereceu blocos de frequência na faixa de 3,5 GHz. As operadoras que adquiriram os blocos de frequência foram: Embratel, Brasil Telecom (Vant), Grupo Sinos, Neovia e WKVE, cada uma com operações distribuídas em algumas regiões do Brasil. Para que esse e outros sistemas de comunicações sem fio sejam implementados com eficiência, muitos esforços têm sido investidos na tentativa de desenvolvimentos de métodos de simulação de predição de cobertura que se aproximem da realidade o melhor possível de forma a que se possam tornar ferramentas fiéis e indispensáveis no planejamento dos sistemas de comunicações sem fio. Neste trabalho foi desenvolvido um algoritmo genético (AG’s) capaz de otimizar os modelos de predição de perda de propagação aplicáveis a faixa de frequência de 3,5 GHz, possibilitando dessa forma uma estimativa do sinal mais próxima da realidade evitando erros significativos no planejamento e implementação de um sistema de comunicação sem fio.

23
  • NATHALEE CAVALCANTE DE ALMEIDA
  • Sistema Inteligente para Diagnóstico de Patologias na Laringe utilizando Máquinas de Vetor de Suporte

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ADRIANO DE ANDRADE BRESOLIN
  • ANA MARIA GUIMARAES GUERREIRO
  • HELIANA BEZERRA SOARES
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • SANDRO GONCALVES DA SILVA
  • Data: Jul 23, 2010


  • Show Abstract
  • A voz humana é uma importante ferramenta de comunicação e qualquer funcionamento inadequado da voz pode ter profundas implicações na vida social e profissional de um indivíduo. Técnicas de processamento digital de sinais têm sido utilizadas através da análise acústica de desordens vocais provocadas por patologias na laringe, devido à sua simplicidade e natureza não-invasiva. Este trabalho trata da análise acústica de sinais de vozes afetadas por patologias na laringe, especificamente, edemas e nódulos nas pregas vocais. A proposta deste trabalho é desenvolver um sistema de classificação de vozes para auxiliar no pré-diagnóstico de patologias na laringe, bem como no acompanhamento de tratamentos farmacológicos e pós-cirúrgicos. Os coeficientes de Predição Linear (LPC), Coeficientes Cepstrais de Freqüência Mel (MFCC) e os coeficientes obtidos através da Transformada Wavelet Packet (WPT) são aplicados para extração de características relevantes do sinal de voz. Para a tarefa de classificação é utilizado a Máquina de Vetor de Suporte (SVM), que tem como objetivo construir hiperplanos ótimos que maximizem a margem de separação entre as classes envolvidas. O hiperplano gerado é determinado pelos vetores de suporte, que são subconjuntos de pontos dessas classes. De acordo com o banco de dados utilizado neste trabalho, os resultaram apresentaram um bom desempenho, com taxa de acerto de 98,46% para classificação de vozes normais e patológicas em geral, e 98,75% na classificação de patologias entre si: edemas e nódulos

24
  • JOILSON BATISTA DE ALMEIDA REGO
  • Identificação de uma planta de corrente de um motor de indução utilizando redes de base radial

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • GUILHERME DE ALENCAR BARRETO
  • Data: Jul 30, 2010


  • Show Abstract
  • O presente trabalho descreve a utilização de uma ferramenta matemática na solução de problemas decorrentes da teoria de controle, incluindo a identificação, a análise do retrato de fase e a estabilidade, bem como a evolução temporal do sistema. A identificação de sistemas é uma área da modelagem matemática que tem como objetivo o estudo de técnicas que possam determinar um modelo dinâmico na representação de um sistema real. A ferramenta utilizada na identificação e análise do sistema dinâmico não linear será as Funções de Base Radial (RBF). O processo ou a planta que será utilizada possui um modelo matemático desconhecido, mas pertence a uma determinada classe que contém uma dinâmica interna que pode ser modelada. A análise de estabilidade da RBF é apresentada. A elevada eficácia da abordagem proposta é ilustrada pela sua aplicação a diversos sistemas físicos (tais como: sistemas elétricos, projeto de controladores, robótica, processos químicos, dentre outros). A identificação utilizando Funções de Base Radial é demonstrada através de simulações computacionais a partir de um conjunto de dados reais obtidos da planta.

25
  • JULIO CESAR PAULINO DE MELO
  • Utilizando a Televisão Digital como um Meio de Comunicação para Ambientes Interativos Reais

  • Advisor : LUIZ EDUARDO CUNHA LEITE
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • GUIDO LEMOS DE SOUZA FILHO
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Aug 2, 2010


  • Show Abstract
  • Esta dissertação foca em prover um mecanismo de comunicação entre telespectadores de TV Digital e Dispositivos de Interação, como robôs, por exemplo, dispostos no ambiente de onde um programa de TV está sendo transmitido. Este mecanismo de comunicação foi projetado usando uma arquitetura baseada em Middleware. Nossa solução consiste em interconectar os dispositivos de interação, de um ambiente em um programa de TV Digital, em uma rede de Dispositivos de Interação. Com essa solução nosso sistema é capaz de gerenciar os dispositivos na rede independente da camada de comunicação física usada por eles, permitindo que os dispositivos se comuniquem entre sí e sejam controlados por aplicações externas. Após, usando uma solução baseada em middleware, nós permitimos que os telespectadores controlem entidades que compõem a rede através de um processo de comunicação
    distribuída e aplicações de controle.

26
  • MELINDA CESIANARA SILVA DA CRUZ
  • LOCALIZAÇÃO DE FALTAS EM LINHAS DE TRANSMISSÃO DE MÚLTIPLOS TERMINAIS A PARTIR DE REGISTROS OSCILOGRÁFICOS SINCRONIZADOS VIA TRANSFORMADA WAVELET

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • FABIANO FRAGOSO COSTA
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • CRISLUCI KARINA SOUZA SANTOS CANDIDO
  • DENIS VINICIUS COURY
  • JOSE JULIO DE ALMEIDA LINS LEITAO
  • Data: Aug 6, 2010


  • Show Abstract
  • A energia elétrica é indispensável para o desenvolvimento da sociedade moderna e sua crescente demanda nos últimos anos, fruto dos crescimentos populacional e econômico, faz com que as concessionárias se tornem mais comprometidas com a qualidade e a continuidade do fornecimento, fatores que são regulamentados pela ANEEL (Agência Nacional de Energia Elétrica). Para que esses fatores sejam atendidos quando ocorre uma falta permanente no sistema, faz-se necessária, primeiramente, uma rápida localização do defeito causador da interrupção da energia, o que não é uma tarefa tão simples devido à complexidade dos sistemas atuais. Um exemplo disso ocorre nas linhas de transmissão com múltiplos terminais, que interligam circuitos existentes com objetivo de atender à demanda. Nestas linhas, derivações para atender a cargas de porte que não justificam economicamente a construção de novas subestações são adotadas como medidas viáveis para aliviar outros circuitos. Este trabalho propõe um algoritmo de localização de faltas que é aplicado em linhas de transmissão com múltiplos terminais – dois e três terminais. O método de localização baseia-se no uso de fasores fundamentais de tensão e corrente, bem como na representação da linha através de sua impedância série. A Transformada Wavelet é uma ferramenta matemática eficaz na análise de descontinuidades de sinais e, por este motivo, é utilizada na sincronização dos dados de tensão e corrente oriundos de faltas. A transformada de Fourier é outra ferramenta utilizada neste trabalho para extração dos fasores fundamentais de tensão e corrente. Para testar e validar a aplicabilidade do algoritmo de localização, utilizaram-se dados de sinais faltosos simulados no ATP (Alternative Transients Program) e também dados reais obtidos de registradores oscilográficos instalados em linhas da CHESF.

27
  • BRUNO GOMES DE ARAUJO
  • Modelo Arquitetural de Comunicação para Monitoramento de Pacientes Baseado em Middleware, Computação Móvel e Ubíqua

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • GLAUCIO BEZERRA BRANDAO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • Data: Aug 10, 2010


  • Show Abstract
  • A Automação Hospitalar consiste numa área que está em constante crescimento. Os processos envolvidos estão sendo informatizados e automatizados cada vez mais com o surgimento de novas tecnologias e novos hardwares. Apesar disso, muitos dos processos envolvidos ainda estão sendo realizados de forma manual, como é o caso do monitoramento de pacientes, considerado um processo crítico por estar envolvido com vidas humanas. Um dos fatores que deve ser levado em conta durante um monitoramento é a agilidade na detecção de alguma anomalia nos sinais vitais de pacientes, assim como o aviso desta anomalia à equipe médica envolvida. Visando isto, o presente trabalho de mestrado visa desenvolver uma arquitetura para automatizar este processo de monitoramento e comunicação de possíveis alertas a um profissional da área, para que o atendimento de urgências possa ser feito de forma eficaz. Foi utilizada a computação móvel e distribuída para a comunicação e envio de mensagens entre uma central localizada no hospital, e o dispositivo móvel portado pelo plantonista.

28
  • JANNAYNA DOMINGUES BARROS FILGUEIRA
  • Estudo da detecção preventiva da osteoporose pela aplicação da variação da permissividade elétrica a partir de sondagem eletromagnética

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • CLAUDIO RODRIGUES MUNIZ DA SILVA
  • JOSE JOSEMAR DE OLIVEIRA JUNIOR
  • ROBSON FERNANDES DE FARIAS
  • SANDRO GONCALVES DA SILVA
  • Data: Aug 13, 2010


  • Show Abstract
  • As doenças Osteometabólicas, entre elas a osteoporose, caracterizam-se pela fragilidade nos ossos e afeta cerca de 10 milhões de brasileiros, na maioria mulheres no período da menopausa. Nessa fase, a ausência do hormônio feminino faz com que os ossos percam cálcio e fiquem porosos como uma esponja. Esta fragilidade dos ossos expõe a mulher a riscos maiores de fraturas tanto por quedas como espontâneas. Os locais mais comuns são a coluna, o colo do fêmur, e o pulso. A doença progride lentamente e raramente apresenta sintomas antes que aconteça algo de maior gravidade, como uma fratura, que costuma ser espontânea, porém, a osteoporose pode ter sua evolução retardada por medidas preventivas.
    A detecção da Osteoporose é feita através da Densitometria Óssea, exame que avalia a densidade de mineração óssea (DMO), permitindo ao médico diagnosticá-la antes do aparecimento de fraturas, avaliar o risco futuro de nova fratura nos doentes que tiveram fratura prévia e monitorizar a eficácia do tratamento. Outros métodos são utilizados para diagnosticar a osteoporose, como Tomografia Computadorizada Quantitativa (TCQ) e Avaliação óssea com ultra-som, porém. Esta dissertação propõe um método capaz de avaliar o nível de massa óssea utilizando ondas eletromagnéticas não ionizantes. Utilizamos também técnicas de processamento de sinais (Wavelet) e reconhecimento de padrões (RNA e KNN)

29
  • CLAUDIO JOSE FRANCA DE MEDEIROS
  • Um Estudo Comparativo de Métodos Não Supervisionados de Redução de Dimensionalidade Aplicados à Visualização de Dados

  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • GUILHERME DE ALENCAR BARRETO
  • JOSE ALFREDO FERREIRA COSTA
  • PABLO JAVIER ALSINA
  • Data: Sep 24, 2010


  • Show Abstract
  • Devido às marcantes evoluções tecnológicas experimentadas nas últimas décadas, a crescente quantidade de informação produzida tem criado novas oportunidades e desafios na área de descoberta do conhecimento e mineração de dados.  Porém, fatores como tamanho das bases de dados, dimensionalidade, problemas de escalonamento e a necessidade descoberta dos padrões escondidos nas massas de dados acrescentam dificuldades à complexa tarefa de análise de dados. Este trabalho aborda comparações qualitativas e quantitativas de métodos de redução de dimensionalidade,  com aplicações a visualização de dados. A avaliação inclui métodos lineares (como análise de componentes principais) e não lineares, como Projeção de Sammon, Redes Auto-associativas, mapas auto-organizáveis, Isomap e LLE. Para as avaliações foram utilizados índices de manutenção da topologia, como medida da qualidade das projeções fornecidas por cada um dos métodos.  Testes enfocaram projeções para espaços bidimensionais, com objetivo de visualizar os resultados, auxiliando etapas subsequentes do processo de mineração de dados. As bases de dados utilizadas incluíram a Wine, Syntethic Control e animals. Os resultados retratam avaliações baseadas em dois aspectos: as visualizações proporcionadas por cada um desses métodos e o grau de fidelidade topológica das projeções obtidas.

30
  • THALES AUGUSTO DE OLIVEIRA RAMOS
  • Estimação da Demanda de Instalações Elétricas de Edificações com Múltiplas Unidades de Consumo

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • ESTEFANE GEORGE MACEDO DE LACERDA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MARCOS ANTONIO DIAS DE ALMEIDA
  • MAX CHIANCA PIMENTEL FILHO
  • Data: Oct 18, 2010


  • Show Abstract
  • Este trabalho tem como objetivo prever a demanda total máxima de um transformador que será usado na rede elétrica para atendimento de uma Múltipla Unidade de Consumo (MUC) ainda inexistente. Em 1987, a COSERN observou que o cálculo de demanda total máxima para uma edificação deveria ser diferente daquele que define o dimensionamento da proteção do ramal de entrada, a fim de não sobredimensionar a potência do transformador. Desde então, houve inúmeras mudanças ocorridas, tanto nos hábitos de consumo da população, como nos aparelhos elétricos, de forma que o presente trabalho envidará esforços para melhorar a estimativa da demanda máxima. Para a realização da pesquisa, foram levantados dados sobre identificação e projetos elétricos de diversas MUCs situadas na Grande Natal. Em algumas delas, foram realizadas medições de demanda durante 7 dias consecutivos e ajustadas para um intervalo de integração de 30 minutos. A estimação da demanda máxima foi feita através de modelos matemáticos que, a partir de um conjunto de informações previamente conhecidos das MUCs, calculam a resposta desejada. Os modelos testados foram regressões lineares simples e múltiplas e redes neurais artificiais. Os diversos resultados calculados ao longo do trabalho foram comparados e, ao final, a melhor resposta encontrada foi posta em comparação com o modelo de estimação proposto anteriormente. 

31
  • FRANCISCO SALES DE LIMA FILHO
  • Mecanismos de segurança para um sistema cooperativo de armazenamento de arquivos baseado em P2P

  • Advisor : SERGIO VIANNA FIALHO
  • COMMITTEE MEMBERS :
  • SERGIO VIANNA FIALHO
  • MARCOS CESAR MADRUGA ALVES PINHEIRO
  • CLAUDIA MARIA FERNANDES ARAÚJO RIBEIRO
  • Data: Nov 3, 2010


  • Show Abstract
  • Trabalhos anteriores estudaram características e peculiaridades das redes P2P, especialmente no que se refere aos aspectos de segurança da informação. A maioria dos trabalhos aborda, de alguma maneira, o compartilhamento de recursos e, em especial, o armazenamento de arquivos. Este trabalho complementa estudos anteriores e acrescenta novas definições referentes a este tipo de sistemas. Foi especificado e construído um sistema de armazenamento seguro, baseado na tecnologia P2P (SAS-P2P), utilizando a plataforma JXTA. Tal sistema utiliza certificados digitais padrão X.509 e PKCS#12 (RSA 1999), emitidos e gerenciados por uma infraestrutura de chaves públicas, que também foi especificada e construída baseada na tecnologia P2P. As informações são armazenadas no sistema SAS-P2P em arquivos no formato XML que é especialmente preparado, facilitando a manipulação e interoperabilidade entre aplicações. O sistema SAS-P2P foi desenvolvido com o intuito de ser oferecido como um serviço complementar da rede GigaNatal, através do qual os participantes dessa rede possam, colaborativamente, construir uma área de armazenamento compartilhada com importantes recursos de segurança como disponibilidade, confidencialidade, autenticidade e tolerância a falhas. Além da especificação, construção e experimentos do sistema SAS-P2P como um todo, também foram realizados testes do módulo PKIX-P2P no que se refere à tolerância a falhas e cálculo efetivo da reputação das autoridades certificadoras participantes do sistema.

32
  • HELTON MAIA PEIXOTO
  • Sistema Não-Intrusivo para Estimação da Direção do Olhar Utilizando Redes Neurais Artificiais

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • ADRIAO DUARTE DORIA NETO
  • HELIANA BEZERRA SOARES
  • CELSO ALBERTO SAIBEL SANTOS
  • Data: Nov 26, 2010


  • Show Abstract
  • Os sentidos fundamentais do corpo humano são: visão, audição, tato, gustação(ou paladar) e olfato. Estes constituem as funções que propiciam o nosso relacionamento com o ambiente. A visão funciona como um receptor sensorial responsável pela captação de informações do mundo exterior que serão enviadas ao cérebro. O olhar reflete a sua atenção, intenção e interesse. Sendo assim, a estimação da direção do olhar, a partir de modelos computacionais, possibilita uma alternativa promissora para melhorar a capacidade de interação homem-máquina, inclusive dos portadores de deficiências motoras. O objetivo deste trabalho consiste em apresentar um sistema não-intrusivo que utiliza basicamente um computador pessoal e uma webcam de baixo custo que, quando aliados ao uso das técnicas de processamento digital de imagens, transformadas Wavelets e reconhecimento de padrões, com as redes neurais artificiais, resultam em um sistema completo que realiza desde a aquisição de imagens (passando pela detecção da face e rastreamento dos olhos) ate a estimação da direção do olhar. Os resultados apresentados mostram a viabilidade do sistema proposto assim como diversas vantagens em seu uso.

33
  • NIELSEN CASTELO DAMASCENO DANTAS
  • Separação cega de fontes lineares e não lineares usando Algoritmo Genético, Redes Neurais Artificiais RBF e Negentropia de Rényi como medida de independência

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ALLAN DE MEDEIROS MARTINS
  • ANA MARIA GUIMARAES GUERREIRO
  • EVANDRO OTTONI TEATINI SALLES
  • Data: Dec 20, 2010


  • Show Abstract
  • Os métodos convencionais para resolver o problema de separação cega de fontes não lineares, em geral, utilizam série de restrições à obtenção da solução, levando muitas vezes, a uma não perfeita separação das fontes originais e alto custo computacional. Neste trabalho, propõe-se uma alternativa de medida de independência com base na teoria da informação e utiliza-se ferramentas da inteligência artificial para resolver problemas de separação cega de fontes lineares e posteriormente não lineares. No modelo linear aplica-se algoritmos genéticos e a Negentropia de Rényi como medida de independência para encontrar uma matriz de separação linear a partir de misturas lineares usando sinais de forma de ondas, áudios e imagens. Fazemos uma comparação com dois tipos de algoritmos de Análise de Componentes Independentes bastante difundido na literatura. Posteriormente, utiliza-se a mesma medida de independência, como função custo no algoritmo genético para recuperar sinais de fontes que foram misturadas por funções não lineares a partir de uma rede neural artificial do tipo base radial. Algoritmos genéticos são poderosas ferramentas de pesquisa global, e, portanto, bem adaptados para utilização em problemas de separação cega de fontes. Os testes e as análises se dão através de simulações computacionais.

34
  • EMANUELE DA SILVA RODRIGUES MONTALVAO
  • Uma Proposta de FSS fractal com Geometria Simplificada

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • LAERCIO MARTINS DE MENDONCA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Dec 21, 2010


  • Show Abstract
  • As Superfícies Seletivas de Frequência (FSS) são estruturas periódicas em uma ou duas dimensões que atuam como filtros espaciais, podendo ser formadas por elementos do tipo patches condutores ou aberturas, funcionando como filtros rejeita-faixa ou passa-faixa, respectivamente. O interesse no estudo das FSS tem crescido através dos anos, pois tais estruturas atendem a requisitos específicos como baixo custo, dimensões e pesos reduzidos, além da possibilidade de se integrar com outros circuitos de micro-ondas. As mais variadas aplicações para tais estruturas têm sido investigadas, como por exemplo, radomes, sistemas de antenas para aviões, filtros eletromagnéticos para antenas refletoras, estruturas absorvedoras, etc. Vários métodos têm sido utilizados para a análise de FSS, dentre eles, o Método das Ondas (WCIP). São diversas as formas de elementos que podem ser utilizados em FSS, como por exemplo, os do tipo fractal, que apresenta uma relativa complexidade geométrica. Este trabalho tem como objetivo principal propor um procedimento de simplificação geométrica de uma FSS fractal, a partir da análise da influência dos detalhes (fendas) da geometria da mesma no comportamento da frequência de ressonância. De forma complementar é mostrado um método simples de ajustar a frequência de ressonância através da análise de uma FSS, que utiliza uma célula básica retangular, na qual são inseridas duas reentrâncias e as dimensões dessas reentrâncias são variadas, tornando possível o ajuste da frequência. Para isso, as estruturas são analisadas numericamente, utilizando o WCIP, e posteriormente são caracterizadas experimentalmente, comparando-se os resultados obtidos. Para os dois casos é avaliada, a influência dos campos elétrico e magnético, este último através do vetor densidade de corrente elétrica. É realizado um estudo bibliográfico acerca do tema e são apresentadas sugestões para a continuidade deste trabalho.

35
  • AUGUSTO CÉSAR PEREIRA DA SILVA MONTALVÃO
  • Caracterização Numérica de Antenas para aplicações RFID utilizando o Método das Ondas – WCIP

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • LAERCIO MARTINS DE MENDONCA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Dec 21, 2010


  • Show Abstract
  • Nos últimos anos, a tecnologia de Identificação por Radiofrequência (RFID) tem ganhado grande interesse tanto de comunidades industriais como de comunidades científicas. A sua capacidade de localizar e monitorar objetos e pessoas com etiquetas passivas ou ativas permite o desenvolvimento fácil, com uma boa relação custo-benefício e ainda apresenta inegáveis benefícios em aplicações que variam de logística a cuidados de saúde, robótica, segurança, entre outras. Dentro desse aspecto o que mais vem se destacando são as etiquetas RFID e as antenas usadas em leitores RFID. A maioria das etiquetas possui antenas omnidirecionais e normalmente são fabricadas como dipolos modificados impressos. O objetivo principal de um projeto de antena para etiqueta é conseguir a impedância de entrada necessária para realizar um bom casamento de impedância com a impedância de carga do microchip. Já o objetivo principal no projeto de antenas para leitores é conseguir estruturas de tamanhos reduzidos e com boa capacidade de transmissão de dados. Este trabalho traz a caracterização numérica de antenas para aplicações RFID, sendo estas divididas em etiquetas RFID e antenas para leitores. São analisadas três etiquetas RFID e duas antenas para leitores RFID encontradas na literatura. A análise dessas estruturas é feita utilizando o Método das Ondas - WCIP. São comparados os resultados iniciais encontrados na literatura com os obtidos através de simulações no WCIP com o objetivo de mostrar que o Método das Ondas é capaz de analisar tais estruturas. Para ilustrar os resultados obtidos nas simulações, é apresentado o comportamento dos campos elétrico e magnético. É realizada também uma revisão bibliográfica a respeito das características e princípios da Tecnologia RFID. São apresentadas, ainda, sugestões de continuidade para este trabalho.

36
  • JOSE IDIFRANSE AGUIAR TRINDADE
  • Caracterização de Superfícies Seletivas de Frequência e de Antenas Fractais para Aplicações em Redes Sem Fio

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • LAERCIO MARTINS DE MENDONCA
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Dec 22, 2010


  • Show Abstract
  • Este trabalho tem como objetivo investigar o comportamento de estruturas fractais em estruturas planares de microfita. Em particular, as antenas patch de microfita e as superfícies seletivas de frequência tiveram seus elementos radiantes tradicionais alterados para a forma geométrica fractal. Para as antenas, usou-se como elemento radiante o fractal de Minkowski. Além do patch retangular, considerado como nível 0, onde nenhuma iteração é feita, os contornos fractais de Minkowski foram aplicados até o nível 3 dessa estrutura, resultando em quatro antenas. O método de alimentação utilizado nas antenas foi a alimentação por linha de microfita. A fim de validar os resultados obtidos na simulação, os protótipos foram construídos e medidos e seus resultados comparados aos simulados. Através da análise gráfica, observou-se a possibilidade de miniaturização das estruturas, além do comportamento multibanda proporcionado pela geometria fractal. Em geral, os resultados medidos mostraram-se concordantes com os resultados simulados. Em particular, a antena fractal de Minkowski de nível 3 foi utilizada para explorar a característica multibanda, possibilitando seu funcionamento simultâneo em duas faixas comerciais Wi-Fi e WiMAX, regulamentadas pela ANATEL. Em seguida, chaves foram colocadas nas bordas fractais da estrutura e seu comportamento eletromagnético foi analisado. A análise levou em consideração as chaves em pares. Observou-se um melhoramento no casamento de impedâncias para algumas frequências da faixa de medição, bem como, esse melhoramento a caracterizou como uma antena reconfigurável em frequência. A geometria fractal também foi utilizada nas superfícies seletivas de frequência. O fractal adotado para atuar como elemento da FSS foi o pentágono de Dürer. Para este caso, o pentágono de Dürer foi implementado até o nível 3, porém o protótipo construído se limitou ao nível 2, uma vez que para o nível 3, as dimensões ficaram muito pequenas impossibilitando desta maneira a sua fabricação. A fim de validar os resultados simulados, as estruturas foram fabricadas e medidas, e estes resultados foram comparados. Mais uma vez, observou-se o comportamento multibanda da estrutura, proporcionado pela geometria fractal. Os resultados promissores motivaram uma análise paramétrica. Com isto, constatou-se que a variação da periodicidade influencia no comportamento eletromagnético da estrutura e essa influência diminui à medida que a iteração fractal aumenta. A largura de banda diminui à medida que a periodicidade aumenta, causando um aumento do fator de qualidade. Esse aumento do fator de qualidade nós fornece uma estrutura mais seletiva para uma determinada frequência. Para caracterizar estas estruturas, utilizamos na simulação o software comercial Ansoft Designer™. Na medição, utilizamos um analisador de redes vetorial, modelo HP8757D da Hewlett Packard.

Thesis
1
  • MARLOS ANDRE MARQUES SIMOES DE OLIVEIRA
  • Um Protocolo de Comunicação Multicast na Camada de Aplicação com Consciência de Localização
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • CARLOS BARROS MONTEZ
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • MARCOS CESAR MADRUGA ALVES PINHEIRO
  • RICARDO ALEXANDRE REINALDO DE MORAES
  • Data: Jan 15, 2010


  • Show Abstract
  • Atualmente aplicações em grupo na Internet estão em ascensão, como por exemplo
    transmissão de áudio e vídeo, computação colaborativa e jogos com múltiplos
    participantes. Isso leva à necessidade de comunicação multicast, mas infelizmente o
    suporte a este tipo de serviço não está amplamente disponível pela camada de rede.
    Por isso, no atual estágio tecnológico surgiram soluções de protocolos multicast
    implementados na camada de aplicação para suprir tal deficiência. Além disso, estas
    aplicações muitas vezes se apresentam simultaneamente como provedores e clientes dos
    serviços utilizados, caracterizando-as como aplicações denominadas peer-to-peer,
    possuindo características dinâmicas, onde os participantes podem entrar e sair de um
    grupo com uma freqüência muito alta. Assim, algoritmos centralizados de gerência de
    grupo não apresentam bom desempenho para essa classe de aplicações, e mesmo as
    soluções peer-to-peer
    tradicionais necessitam ter algum mecanismo que leve em consideração essa
    mobilidade. A idéia de consciência de localização permite distribuir os
    participantes na rede virtual de acordo com a sua proximidade na rede física,
    permitindo um bom desempenho nas operações de gerenciamento do grupo. Diante deste
    contexto, nesta tese é proposto um protocolo de comunicação multicast na camada de
    aplicação, que leva em consideração a topologia da rede real no processo de
    montagem da rede virtual. O algoritmo de gerência de grupos utiliza uma nova
    métrica para prover a consciência de localização, e foi implementado utilizando uma
    árvore distribuída compartilhada e bi-direcional, possuindo uma heurística
    sub-ótima para o processo de inclusão de novos participantes que visa minimizar o
    custo de construção da árvore de distribuição de dados. A avaliação da proposta foi
    realizada de duas formas distintas: i) através de um simulador
    próprio onde se procurou avaliar a qualidade de construção da árvore de
    distribuição gerada, avaliando-se métricas como o número de filhos por cada nó e a
    distância final entre os nós; e ii) através de cenários reais construídos no
    simulador de redes ns-3, onde foi avaliado o desempenho do protocolo através de
    métricas como stress, stretch e tempos de associação e reconfiguração dos grupos.
2
  • RUMMENIGGE RUDSON DANTAS
  • GATE – Uma abordagem baseada em middleware para aplicações interperceptivas envolvendo múltiplos dispositivos

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ALEJANDRO CESAR FRERY ORGAMBIDE
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • ELIANA SILVA DE ALMEIDA
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • TATIANA AIRES TAVARES
  • Data: Jan 18, 2010


  • Show Abstract
  • Neste trabalho, estendemos o conceito da Interpercepção para a integração com aplicações da TV Digital, celulares e outros dispositivos portáteis como PDA e Palm-Tops. Através desta extensão, pretendemos garantir a execução de ambientes virtuais na TV Digital e celulares, bem como a sua integração com a versão deste ambiente executada em um computador pessoal (PC) ou mesmo um celular. Assim usuários que acessarem a versão do ambiente pelo computador poderão interagir com aqueles que acessarem o mesmo ambiente pela TV Digital. Esta mesma extensão da Interpercepção poderá ser utilizada para criação de jogos que também serão compartilhados pelos usuários do computador e da TV Digital.

3
  • SAMAHERNI MORAIS DIAS
  • Controle Adaptativo Robusto para um Modelo Desacoplado de um Robô Móvel

  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • EDSON ROBERTO DE PIERI
  • MÁRIO SARCINELLI FILHO
  • PABLO JAVIER ALSINA
  • Data: Feb 1, 2010


  • Show Abstract
  • Esta tese apresenta o desenvolvimento de uma nova estrutura de controlador adaptativo robusto aplicado a sistemas robóticos móveis com rodas (robô móvel de superfície) e restrições não-holonômicas de movimento. Este controlador atua tanto na dinâmica como na cinemática do robô, e pode ser dividido em duas partes distintas. A primeira parte controla a dinâmica, através da utilização de controladores adaptativos por modelo de referência e estrutura variável. A segunda parte controla a cinemática do robô através de um controlador de posição, cujo objetivo é fazer com que o robô seja capaz de atingir um ponto qualquer no plano cartesiano, sendo que este controlador cinemático é baseado apenas em informações da configuração do robô. O trabalho aplica um método de desacoplamento para transformar o modelo linear do robô móvel, que é um sistema com múltiplas entradas e múltiplas saídas, em dois sistemas desacoplados com apenas uma entrada e
    uma saída, para reduzir a complexidade do projeto do controlador. Em seguida, aplica-se um controlador adaptativo por modelo de referência e estrutura variável a cada um dos sistemas resultantes. Um controlador será responsável pelo erro linear e o outro pela orientação do robô, sendo que estes controladores utilizam como referências sinais provenientes do controlador de posição. Para comprovar o funcionamento da estrutura proposta, utilizam-se resultados simulados e experimentais para o robô móvel com acionamento diferencial de um kit de futebol de robôs. O simulador possui as principais características do sistema físico real, dentre as quais podem-se destacar os ruídos de entradas e as não-linearidades como zona morta e saturação. Os resultados experimentais foram obtidos através de um programa desenvolvido em C++ e aplicado a um kit de futebol de robôs da empresa Microrobot no laboratório de acionamento, controle e instrumentação da Universidade Federal do Rio Grande do Norte (LACI/UFRN). Os resultados simulados e experimentais são apresentados e discutidos ao final da tese.

4
  • RAIMUNDO VIEGAS JUNIOR
  • Group Sequential Communication (GSC): Especificação e Análise de Desempenho de um Mecanismo de Comunicação de Tempo Real Compatível ao Padrão IEEE 802.11/11e Aplicado à Automação Industrial

  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADILSON BARBOZA LOPES
  • CARLOS BARROS MONTEZ
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARCOS CESAR MADRUGA ALVES PINHEIRO
  • Data: Feb 11, 2010


  • Show Abstract
  • Esta tese propõe a especificação e análise de desempenho de um mecanismo de comunicação de tempo real compatível com o Padrão IEEE 802.11/11e, chamado Group Sequential Communication (GSC). O GSC apresenta um melhor desempenho quando comparado ao mecanismo HCCA para tratar pequenos pacotes de dados, além de adotar uma abordagem descentralizada do controle de acesso ao meio baseado no conceito produtor/consumidor. O objetivo principal da proposta é a redução de overheads da rede, oriundos de quadros de Polling, ACK e QoS Null trocados entre o controlador híbrido e as estações no HCCA padrão. O mecanismo GSC elimina o uso de quadros de
    Polling utilizados pelo escalonador do HCCA, através de um procedimento de Virtual Token Passing entre os membros do grupo de tempo real, a quem é garantida alta prioridade de acesso ao meio de forma sequencial. A fim de melhorar a confiabilidade da proposta em ambientes ruidosos é apresentado um esquema de recuperação de erro chamado algoritmo de segunda chance.
    Este esquema é baseado em uma estratégia de reconhecimento em bloco das mensagens enviadas, com possibilidade de serem retransmitidas quando não recebidas com sucesso. Desta forma, o mecanismo GSC mantém o tráfego das estações de tempo real entre os diversos dispositivos compatível ao Padrão IEEE 802.11/11e, com o uso otimizado da banda e variações mínimas de atraso médio entre as entregas dos pacotes de dados pertencentes à rede sem fio. Para propósito de validação da proposta, os mecanismos GSC e HCCA foram implementados através de um software de simulação de redes desenvolvido em C/C++ e os resultados de desempenho foram comparados. Os experimentos mostram a eficiência do mecanismo GSC, principalmente em cenários de comunicações industriais.

5
  • CLOVIS BOSCO MENDONCA OLIVEIRA
  • Título: Técnicas de Simplificação de Redes e Otimização Multiobjetivo para Análise de Variações de Tensão em Regime Permanente Provocadas por Parques Eólicos Integrados ao Sistema Elétrico.

  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • ESTEFANE GEORGE MACEDO DE LACERDA
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • MAX CHIANCA PIMENTEL FILHO
  • RICARDO FERREIRA PINHEIRO
  • SELÊNIO ROCHA SILVA
  • UBIRATAN HOLANDA BEZERRA
  • Data: Mar 12, 2010


  • Show Abstract
  • Este trabalho apresenta uma descrição do desenvolvimento de modelo para representação de rede simplificada aplicado em fluxo de carga híbrido para cálculo das variações de tensão em regime permanente provocadas pela conexão de aerogeradores na rede elétrica. Além disso, se apresenta um fluxo de carga ótimo capaz de controlar remotamente o fator de potência na barra de conexão e minimizar perdas. O princípio do processo de análise do sistema, conduzido pelo acessante, tem como base dados técnicos fornecidos pela rede acessada. Assim, se propõe um modelo para simplificação de redes que permita a necessidade do conhecimento apenas dos dados referente a rede interna, ou seja, a parcela da rede de interesse para análise. Dessa forma, pretende-se fornercer meios para auxiliar na sistematização das relações entre concessionária e acessante. O modelo para simplificação de rede proposto identifica a rede interna, rede externa e as barras de fronteira a partir de dados provenientes de um estudo de vulnerabilidade da rede, atribuindo-as potências líquidas flutuantes, ou seja, modelando-as como barras slack. Aplica-se o referido modelo no fluxo de carga Newton-Raphson e em um fluxo de carga híbrido, composto pelos métodos de Gauss Seidel Zbarra e Soma de Potências. Ao final, apresentam-se os resultados obtidos por um ambiente computacional desenvolvido do SCILAB e FORTRAN, com suas respectivas análises e conclusões, comparando-os com o ANAREDE.

6
  • MARCONI CAMARA RODRIGUES
  • Identificação Fuzzy-Multimodelos para Sistemas Não Lineares

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • CAIRO LUCIO NASCIMENTO JUNIOR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • Data: Mar 16, 2010


  • Show Abstract
  • Este trabalho apresenta uma nova técnica de identificação multimodelos baseada em ANFIS para sistemas não lineares. Nesta técnica, a estrutura utilizada é do tipo \emph{fuzzy} Takagi-Sugeno cujos consequentes são modelos lineares locais que representam o sistema em
    diferentes pontos de operação e os antecedentes são funções de pertinência cujos ajustes são realizados pela fase de aprendizagem da técnica neuro-fuzzy ANFIS. Modelos que representem o sistema em diferentes pontos de operação podem ser encontrados com técnicas de linearização como, por exemplo, o método de Mínimos Quadrados que é robusto a ruídos e de simples aplicação. Cabe à fase de implicação do sistema fuzzy informar a proporção de cada modelo que deve ser
    empregada, utilizando, para isto, as funções de pertinência. As funções de pertinência podem ser ajustadas pelo ANFIS com o uso de algoritmos de redes neurais, como o de retropropagação do erro, de modo que os modelos encontrados para cada região sejam devidamente interpolados e, assim, definam-se a atuação de cada modelo para as possíveis entradas do sistema. Em multimodelos a definição de atuação de modelos é conhecida por métrica e, como neste trabalho é realizada pelo ANFIS, será denominada de métrica ANFIS. Desta forma, uma métrica ANFIS é utilizada para interpolar vários modelos, compondo o sistema a ser identificado. Experimentos são realizados em um tanque didático, com multisseções, projetado e desenvolvido ao longo dessa pesquisa, com a finalidade de mostrar características da técnica.

7
  • CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS
  • Desenvolvimento de Antenas de Microfita com Patch em Anel Utilizando Materiais Ferrimagnéticos e Metamateriais

  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • CASSIO GONCALVES DO REGO
  • JEFFERSON COSTA E SILVA
  • LUIZ ALENCAR REIS DA SILVA MELLO
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • SANDRO GONCALVES DA SILVA
  • Data: Apr 19, 2010


  • Show Abstract
  • Em geral, os materiais utilizados como substratos no projeto de antenas de microfita são: dielétricos isotrópicos, dielétricos anisotrópicos e ferrimagnéticos (anisotrópicos magnéticos). No entanto, o uso de materiais ferrimagnéticos em substratos de antenas de microfita do tipo patch tem-se concentrado em análises que utilizam geometrias circulares e retangulares. Na última década, uma nova classe de materiais com características bianisotrópicas, apresentando permissividade e permeabilidade tensoriais, tem surgido e despertado bastante interesse, sendo denominados metamateriais. Portanto, este trabalho apresenta uma análise teórica e numérica das características ressonantes de uma antena de microfita com patch em anel, utilizando como substratos materiais ferrimagnéticos e metamateriais. A análise utiliza o formalismo de onda completa através da aplicação do método dos potenciais vetoriais de Hertz, no domínio da transformada de Hankel. A definição dos potenciais vetoriais de Hertz e a imposição das condições de contorno adequadas à estrutura permitem determinar as funções diádicas de Green, relacionando as componentes da densidade de corrente no patch com as componentes tangenciais do campo elétrico. O método de Galerkin é então usado para obter a equação matricial, cuja solução não trivial fornece a freqüência de ressonância da antena. A partir da modelagem, é possível obter resultados para a freqüência de ressonância em função de vários parâmetros da antena de microfita com patch em anel, para diferentes configurações e substratos, além do diagrama de radiação, perda de retorno e da largura de banda. São consideradas estruturas de antenas de microfita com patch em anel sobre múltiplas camadas ferrimagnética/metamaterial sobre dielétrico isotrópico. A análise numérica para antenas com uma única camada ferrimagnética/metamaterial e para antenas suspensas são obtidas como casos particulares.

8
  • JEAN PAUL DUBUT
  • Conversor CC/CA de Alta Freqüência Baseado em Inversores Ressonantes com Comutação Seqüencial para Excitação de uma Tocha Indutiva a Plasma Térmico.

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • FERNANDO SOARES DOS REIS
  • FRANCISCO DE ASSIS OLIVEIRA FONTES
  • Data: Jul 15, 2010


  • Show Abstract
  • Este trabalho descreve o estudo, a análise e a metodologia de projeto de um conversor ressonante CC/CA de alta freqüência usando técnicas de comutação seqüencial (sequential pulse gating), para a excitação de uma tocha indutiva a plasma térmico. Esta tese objetiva mostrar a potencialidade desta nova técnica de modulação e apresentar uma alternativa tecnológica para o projeto de conversores de potência em altas freqüências. O conversor ressonante opera na freqüência nominal de 400kHz, com potência de 50kW, e é constituído por células inversoras empregando chaves IGBTs de comutação rápida. Para minimizar as perdas de comutação no corte, as células ressonantes operam no modo de chaveamento suave “ZVS”, referenciado por uma malha “PLL” modificada que mantém esta condição estável em função das variações de carga. A estratégia de comando empregada permite operar os dispositivos IGBTs no seu limite superior de corrente usando a propriedade “derating” proporcionada pelo modo de seqüenciamento e aproveitar o efeito de multiplexação que soma as freqüências de cada um dos inversores. A saída do conversor é conectada a um circuito ressonante série formado pelo aplicador da tocha a plasma e um capacitor de compensação, por intermédio de um transformador de adaptação de impedâncias. Inicialmente, é feita uma retrospectiva das razões que originaram e motivaram o desenvolvimento deste projeto. Na seqüência dos capítulos desta tese é apresentada a planta onde o conversor está sendo usado, o estudo das diversas soluções e topologias usadas em conversores ressonantes, as possíveis estratégias de comando, a análise e modelagem do sistema, o dimensionamento e a implementação dos módulos, bem como os resultados experimentais e ensaios conduzidos em laboratório como forma de validar as metas estabelecidas e comprovar o pleno atendimento das especificações propostas.

9
  • RANILSON CARNEIRO FILHO
  • DESENVOLVIMENTO DO SUBSTRATO CERÂMICO BINBO4 PARA ANTENAS DE MICROFITA DE SISTEMAS DE COMUNICAÇÕES SEM FIO

  • Advisor : LAERCIO MARTINS DE MENDONCA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • JOSE HUMBERTO DE ARAUJO
  • LAERCIO MARTINS DE MENDONCA
  • MURILO ARAUJO ROMERO
  • Data: Jul 27, 2010


  • Show Abstract
  • Nos últimos anos, diversos esforços foram feitos visando à utilização de novos materiais na construção de dispositivos usados na faixa de freqüência de microondas, incluindo as antenas de microfita. Dentre estes, destacam-se os materiais cerâmicos de alta permissividade elétrica, as ferritas e os metamateriais. Neste trabalho, foram projetados e construídos substratos dielétricos cerâmicos de alta permissividade elétrica usando o niobato de bismuto, dopado com óxido de vanádio. Estes substratos foram utilizados na construção de antenas de microfita para operar na faixa de freqüências de microondas, e, em particular, na faixa de comunicações sem fio. Além de possuirem possui baixo peso, um valor de temperatura relativamente baixa na sinterização, seus materiais constituintes são de fácil aquisição, sua construção é relativamente simples e de baixo custo. O uso deste tipo de material cerâmico proporciona uma redução no tamanho das antenas, uma grande eficiência de radiação e boa integração com outros circuitos de microondas.

10
  • DAVI BIBIANO BRITO
  • Metamaterial Inspired Improved Antennas and Circuits

  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • HUMBERTO CESAR CHAVES FERNANDES
  • JOSÉ RICARDO BEGMANN
  • Data: Dec 6, 2010


  • Show Abstract
  • Metamaterials exhibiting negative refraction attracted a great amount of attention in recent years mostly due to their exquisite electromagnetic properties. These matirials are artificial structures that exhibit characteristics not found in nature. It is possible to obtain a metamaterial by combining artificial structures periodically. We investigated the unique properties of Split Ring Resonators, High impedance Surfaces and Frequency Selective Surfaces and composite metamaterials. We have successfully demonstrated the practical use of these structures in antennas and circuits. We experimentally confirmed that composite metamaterial can improve the performance of the structures considered in this thesis, at the frequencies where electromagnetic band gap transmission takes place.

2009
Dissertations
1
  • Danise Suzy da Silva Oliveira
  • Desenvolvimento e Implementação de um Sistema de Supervisão e Controle Residencial
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • Data: Jan 23, 2009


  • Show Abstract
  • Com o avanço tecnológico as pessoas estão cada vez mais buscando praticidade, comodidade e segurança para seus lares. A automação residencial vem ganhando espaço no mercado não só pelo status e modernidade que proporciona, mas também por permitir uma melhor utilização de recursos naturais, diminuindo assim as despesas para se manter uma residência. Este trabalho consiste no desenvolvimento de um sistema de controle e supervisão destinado à automação residencial. O software desenvolvido vai trabalhar juntamente com um controlador (CLP), atuando no gerenciamento, controle e supervisão de todos os dispositivos ligados a ele, oferecendo ao usuário um ambiente simples e prático para o controle de sua residência.
2
  • FELIPE DENIS MENDONCA DE OLIVEIRA
  • Desenvolvimento de um Software de Comunicação sem Fio Aplicado à Instrumentação de Unidade de Elevação de Petróleo Tipo Plunger Lift
  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRES ORTIZ SALAZAR
  • CARLOS ALBERTO VILLACORTA CARDOSO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Feb 13, 2009


  • Show Abstract
  • Este trabalho tem por finalidade desenvolver um software aplicado a um sistema de comunicação de uma rede de sensores sem fio (RSSF), para monitoramento de variáveis analógicas, digitais e comando de válvulas de passagem do fluxo de gás em unidades de elevação artificial de petróleo e gás natural do tipo Plunger Lift. A razão desta implementação deve-se ao fato que, na configuração da planta estudada, os sensores comunicam-se com o CLP (Controlador Lógico Programável) através de cabos e dutos, dificultando eventuais modificações nesse sistema, tais como mudança de layout do mesmo, além de inconveniências que venham a surgir da própria natureza do local, como a presença de animais nas redondezas que tendem a destruir os cabos de interconexão dos sensores ao CLP. Para o desenvolvimento do software, foi utilizado o método de comunicação polling, através do protocolo SMAC (Simple Medium Access Control - padrão IEEE 802.15.4), no ambiente CodeWarrior, ao qual gerou um firmware, carregado nas placas de monitoramento da RSSF, presentes no kit MC13193-EVK, (todos os itens descritos acima são proprietários da Freescale Semiconductors Inc.). O monitoramento e parametrização da rede utilizou uma aplicação, desenvolvida no software LabVIEW, da National Instruments. Os resultados foram obtidos através da observação do comportamento da rede de sensores proposta, focando aspectos, tais como: quantidade de pacotes recebidos e perdidos em ambientes externos (Outdoor) e internos (Indoor), aspectos gerais de confiabilidade na transmissão dos dados, coexistência entre outros tipos de redes sem fio e consumo de energia sob diferentes condições de operação. Os resultados obtidos foram considerados satisfatórios, o que comprovou a eficiência do software neste sistema de comunicação.
3
  • ROBERTO RANNIERE CAVALCANTE DE FRANCA
  • Bianisotropia Uniaxial em Estruturas Irradiantes com Multicamadas e Supercondutores
  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • Data: Feb 19, 2009


  • Show Abstract
  • Este trabalho apresenta a análise teórica e numérica dos parâmetros de uma antena de micro?ta do tipo retangular sobre substrato bianisotrópico e também incluindo simul-taneamente supercondutor na antena. É aplicada a teoria de onda completa do método da Linha de Transmissão Transversa - LTT, para a caracterização das grandezas do substrato e obtenção das equações gerais dos campos eletromagnéticos. É realizado um estudo através da teoria bianisotrópica com o intuito de obter alguns parâmetros. Os mesmos são caracterizados através de tensores permissividade e permeabilidade, chegando-se às equações gerais para os campos eletromagnéticos da antena. É apresentado um estudo das principais teorias que explicam o fenômeno da super-condutividade. As teorias BCS, Equações de London e modelo dos Dois Fluidos são usadas no estudo nas antenas de microfita com estrutura bianisotrópica pela primeira vez. A inclusão do patch supercondutor é feita utilizando-se a condição de contorno com-plexa resistiva. Em seguida é obtida a freqüência de ressonância complexa. São simu-lados vários parâmetros de antenas com o intuito de diminuir as dimensões físicas e aumentar a largura de banda das mesmas. Os resultados são apresentados através de gráficos. A análise teórico-computacional desse trabalho se mostra precisa e relati-vamente concisa. São apresentadas as conclusões e sugestões para trabalhos futuros.
4
  • JOÃO PAULO QUEIROZ DOS SANTOS
  • Uma Implementação Paralela Híbrida para o Problema do Caixeiro Viajante usando Algoritmos Genéticos, GRASP e Aprendizagem por Reforço
  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • JORGE DANTAS DE MELO
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Mar 6, 2009


  • Show Abstract
  • As metaheurísticas são técnicas conhecidas para a resolução de problemas otimização de problemas classificados como NP-Completos e vêm obtendo sucesso na obtenção de soluções aproximandas de boa qualidade. Elas fazem uso de abordagens não determinísticas que geram soluções que se aproximam do ótimo, mas no entanto, sem a garantia de que se encontre o ótimo global. Motivado pelas dificuldades em torno da resolução destes problemas, esse trabalho se propôs o desenvolvimento de métodos paralelos híbridos utilizando a aprendizagem por reforço e as metaheurísticas GRASP e Algoritmos Genéticos. Com a utilização dessas técnicas em conjunto, contribuir para uma melhor eficiência na obtenção das soluções. Neste caso, ao invés de utilizar o algoritmo Q-learning da aprendizagem por reforço, apenas como técnica de geração das soluções iniciais das metaheurísticas, utilizá-lo de forma cooperativa e competitiva com o Algoritmo Genético e o GRASP, em uma implementação paralela. As implementações realizadas neste trabalho apresentaram resultados satisfatórios, tanto na parte de cooperação e competição entre eles, quanto na parte de cooperação e competição entre grupos, em algumas instâncias foram encontradas o ótimo global, quando não encontrado conseguiu-se chegar bem próximo do ótimo global. Foi feito uma análise do desempenho da abordagem proposta e verificou-se um bom comportamento em relação aos quesitos que comprovam a eficiência e o speedup das implementações realizadas.
5
  • TALLES RODRIGUES FERREIRA
  • Modulação Quantizada para Sistemas com Codificação Wavelet Sujeitos ao Desvanecimento Rayleigh
  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • FABIANO FRAGOSO COSTA
  • JEFFERSON COSTA E SILVA
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • SANDRO GONCALVES DA SILVA
  • Data: Mar 12, 2009


  • Show Abstract
  • A codificação por matrizes wavelets tem se mostrado um método eficiente para combater o desvanecimento, fenômeno que causa flutuações na intensidade do sinal transmitido em um canal de comunicação sem fio, devido à propagação por múltiplos percursos. Mas como os símbolos codificados pelo sistema wavelet são não-equiprováveis, os esquemas de modulação influenciam de maneira fundamental o desempenho desse sistema. Por isso se torna essencial um método eficaz para a obtenção desses esquemas de modulação de forma a otimizar o desempenho do sistema wavelet, principalmente quando se emprega matrizes wavelets de grandes dimensões. Esse trabalho aborda o projeto de esquemas de modulação para um sistema de transmissão sem fio baseado na codificação por matrizes wavelets em canais com desvanecimento Rayleigh plano. Para o projeto desses esquemas de modulação são criados novas constelações e esquemas de quantização. O projeto desses esquemas de modulação é guiado por um algoritmo genético. Os esquemas obtidos são simulados em canais com desvanecimento Rayleigh e os resultados são apresentados.
6
  • JOAO DE DEUS FREIRE DE ARAUJO
  • UMA METODOLOGIA PARA REDUÇÃO DE INCERTEZAS EM SISTEMA DE MEDIÇÃO DE VAZÃO DE ÓLEO E GÁS

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • BENNO WALDEMAR ASSMANN
  • Data: Mar 23, 2009


  • Show Abstract
  • O objetivo deste trabalho de pesquisa é abordar a necessidade de implementação de novas alternativas para a execução da gestão no controle metrológico: quanto às verificações das medições iniciais e posteriores; nos procedimentos de controle da incerteza de medição; aplicada na avaliação das perdas ou sobras constatadas nas operações de movimentação de granéis líquidos; quando utilizamos medidores tipo turbina na medição fiscal utilizada nos negócios da Petrobras, em virtude ao atual cenário da metrologia legal e científica; no contexto nacional e internacional. Almeja-se, com estas alternativas: padronizarmos a minimização dos erros aleatórios e sistemáticos; a estimativa dos erros remanescentes; assim como, a gestão no controle metrológico dos procedimentos de calibração; controle das incertezas de medições; e contribuirmos para a mudança na forma de atuação da metrologia legal e científica, divulgando novas informações para a gestão de mudanças do controle metrológico, voltadas objetivamente para os aspectos de supervisão na execução destas atividades no controle das incertezas de medição utilizadas em nossos processos de medição fiscal no sistema Petrobras. São apresentados resultados, informações e comentários sobre a influência da incerteza de medição nos resultados atuais das medições fiscais e transferências de custódia. Isto enfatizará a necessidade, dentre outras coisas, de melhoria e na ampliação do controle metrológico monitorado, definindo um melhor atendimento à demanda de calibrações dos equipamentos e instrumentos de medições da Petrobras. Finalmente, pretendese concluir pela necessidade do aprimoramento do método de avaliação dos dados do medidor aplicado na gestão atual do controle de incertezas de medições, propondo metodologia para a abordagem do problema, assim como, destacando os resultados esperados.

7
  • LUCIANO PEREIRA DOS SANTOS JUNIOR
  • Uma Fonte Chaveada de 50kW Com Correção de Fator de Potência Para Alimentação de uma Tocha de Plasma Indutiva, Utilizando Técnicas de Controle Digital

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • MARCELO CABRAL CAVALCANTI
  • Data: Apr 17, 2009


  • Show Abstract
  • O presente trabalho trata do desenvolvimento de um estudo experimental sobre uma fonte de alimentação de alta freqüência que alimentará a tocha plásmica a ser implementada no projeto PLASPETRO, o qual consta de dois conversores estáticos desenvolvidos com o uso de transistores Insulated Gate Bipolar Transistor (IGBT). Os drivers utilizados no controle dessas chaves são acionados por um controlador de sinal digital -Digital Signal Processor (DSP) através de fibras ópticas a fim de reduzir problemas com interferência eletromagnética -Electricomagnetic Interference (EMI). O primeiro consiste de um estágio pré-regulador na forma de um conversor CA-CC boost trifásico com correção de fator de potência, cujo é tema principal deste trabalho, enquanto o segundo consiste na fonte de alta frequência propriamente dita. Um inversor série-ressonante composto por 4 (quatro) células inversoras operando a uma frequência de cerca de 115 kHz cada, em modo de comutação suave, alternando-se para fornecer à carga (tocha de plasma) uma corrente alternada com uma frequência de 450 kHz. O primeiro estágio tem a função de fornecer ao inversor série-ressonante uma tensão CC de valor controlado a partir da rede de alimentação disponibilizado pelo sistema elétrico da concessionária, além de corrigir o fator de potência do sistema como um todo. Esse nível CC de tensão no barramento de saída do primeiro estágio será utilizado para o controle da potência transferida pelo inversor à carga. Podendo variar desde 550Vcc até um valor máximo de 800Vcc. Para controlar o nível de tensão do barramento CC utilizou-se um controlador Proporcional Integral (PI) e para atingir o fator de potência unitário utilizou-se dois outros PIs para controle das correntes em referencial estacionário. Este conversor utiliza controle vetorial a fim de diminuir as perdas por chaveamento. Simulações computacionais foram realizadas para auxiliar no dimensionamento e previsão de performance. Todo o controle e comunicações necessárias ao estágio supervisório foram implementadas em um DSP.

8
  • WILMA MARIA DA COSTA MEDEIROS
  • SisOnt - Sistema de Informação em Saúde Baseado em Ontologias
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • GLAUCIO BEZERRA BRANDAO
  • HELIANA BEZERRA SOARES
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Apr 24, 2009


  • Show Abstract
  • O compartilhamento de conhecimentos e integração de dados é um dos maiores desafios da área da Saúde e essencial para contribuição de melhoria da qualidade da assistência em saúde. Uma vez que a mesma pessoa recebe atendimento em diversas instituições de saúde ao longo de sua vida, suas informações ficam distribuídas em diferentes sistemas de informação que são executados em plataformas de hardware e software heterogêneas. Este trabalho propõe um sistema de informação em saúde baseado em ontologias (SISWeb) para compartilhamento de conhecimento e integração de dados em saúde, que permite inferir novas informações a partir de bases de dados e da base de conhecimento, para esse fim foram criadas três ontologias representadas através dos padrões e conceitos propostos pela Web Semântica. A primeira ontologia provê a representação dos conceitos de agravos [SVS 2006] e as demais estão relacionadas à representação dos conceitos das bases de dados dos sistemas de informação em saúde (SIS), especificamente do sistema de informação de agravos de notificação (SINAN) e do sistema de informações sobre mortalidade (SIM).
9
  • TIAGO HIROSHI KOBAYASHI
  • Uma Ferramenta de Manipulação de Pacotes para Análise de Protocolos de Redes Industriais Baseados em TCP/IP
  • Advisor : PAULO SERGIO DA MOTTA PIRES
  • COMMITTEE MEMBERS :
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • JORGE DANTAS DE MELO
  • JOSÉ SÉRGIO DA ROCHA NETO
  • PAULO SERGIO DA MOTTA PIRES
  • Data: Jun 7, 2009


  • Show Abstract
  • Neste trabalho é apresentada uma ferramenta de manipulação de pacotes destinada à realização de testes em dispositivos que implementam protocolos de comunicação baseados em TCP/IP utilizados em redes industriais. A ferramenta foi desenvolvida em linguagem de programação Python, como uma extensão ao Scapy. Esta ferramenta, denominada IndPM - Industrial Packet Manipulator, permite testar os dispositivos presentes em redes industriais em relação a possíveis vulnerabilidades, realizar testes de conformidade de protocolos, coletar respostas de servidores existentes nas redes e utilizar os recursos do interpretador Python para compor testes. Como prova de conceito, foi implementado o protocolo Modbus/TCP. O protocolo DNP3 sobre TCP também foi implementado, mas não foi testado por indisponibilidade de recursos. Os resultados dos testes obtidos com a manipulação de pacotes Modbus/TCP mostram falhas de implementação em um módulo de comunicação para um Controlador Lógico Programável bastante utilizado na indústria.
10
  • JOAO PAULO DE SOUZA MEDEIROS
  • Identificação Remota de Sistemas Operacionais Utilizando Análise de Processos Aleatórios e Redes Neurais Artificiais
  • Advisor : AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • EDUARDO BRAULIO WANDERLEY NETTO
  • JORGE DANTAS DE MELO
  • PAULO SERGIO DA MOTTA PIRES
  • Data: Jun 19, 2009


  • Show Abstract
  • É proposto um novo método para identificação remota de sistemas operacionais que operam em redes TCP/IP. Tal procedimento possui diversas aplicações relacionadas à segurança em redes de computadores e é normalmente adotado tanto em atividades de ataque quanto de defesa de sistemas. O método proposto é capaz de obter sucesso em situações onde diversas soluções atuais falham, inclusive na lide com dispositivos sensíveis. A novo método realiza a análise dos geradores de números aleatórios usados nas pilhas TCP/IP e, usando redes neurais artificiais, cria mapas que representam o comportamento destes geradores. Tais mapas são usados para comparação com mapas rotulados que representam sistemas já conhecidos, concretizando o processo de identificação.
11
  • EVELLYNE DA SILVA BATISTA
  • Desenvolvimento de uma Ferramenta Computacional para Aplicação no Método de Elevação por Bombeio Centrífugo Submerso
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • BENNO WALDEMAR ASSMANN
  • RUTACIO DE OLIVEIRA COSTA
  • Data: Jun 26, 2009


  • Show Abstract
  • O Bombeio Centrífugo Submerso (BCS) tem se mostrado uma das soluções mais adequadas como método de elevação em aplicações onshore e offshore. As características típicas desssas aplicações são condições adversas de temperatura, fluidos viscosos e ambientes gaseificados. As dificuldades encontradas na manutenção e instalação de equipamentos são fatores que oneram a produção de petróleo em águas profundas, com isso, a otimização via automação, pode ser um passo fundamental para a redução de custos e falhas nos equipamentos de subsuperfície. Este trabalho apresenta um simulador computacional relacionado ao método de elevação artificial BCS. A ferramenta representa o comportamento dinâmico, considerando a transmissão de energia elétrica da superfície ao motor, modelo do motor elétrico (incluindo o efeito térmico), simulação do escoamento na tubulação, simulação do comportamento da bomba centrífuga, levando em consideração os efeitos da natureza do líquido e os aspectos do reservatório. Adicionalmente, são encontrados animações tridimensionais para cada subsistema BCS (transformador, motor, bomba, selo ou protetor, separador de gás e quadro de comando). O simulador computacional propõe uma melhoria no acompanhamento de poços de petróleo visando o aumento da produtividade do poço. Atualmente, os simuladores comerciais estão baseados em equipamentos específicos do fabricante, dificultando obter resultados com outros equipamentos. Na técnica proposta, existe suporte para diversos fabricantes.
12
  • CARLOS MANUEL DIAS VIEGAS
  • Análise de Desempenho de Estratégias de Retransmissão para o Mecanismo HCCA do Padrão de Redes Sem Fio IEEE 802.11e
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • ADRIAO DUARTE DORIA NETO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Jul 3, 2009


  • Show Abstract
  • Este trabalho apresenta a análise de desempenho de algoritmos de retransmissão de tráfego propostos para o mecanismo de acesso ao meio HCCA do padrão IEEE 802.11e aplicados ao ambiente industrial. Devido à natureza deste tipo de ambiente, repleto de interferências eletromagnéticas, e à do meio de transmissão sem fio do padrão IEEE 802.11, susceptível a tais interferências, em conjunto com a ausência de mecanismos de retransmissão, remete a uma situação impraticável para garantias de qualidade de serviço ao tráfego de tempo real, ao qual o padrão IEEE 802.11e se propõe e este tipo de ambiente requer. Desta forma, para resolver este problema, este trabalho propõe uma nova abordagem que engloba a criação e avaliação de algoritmos de retransmissão com o intuito de garantir um nível de robustez, confiabilidade e qualidade de serviço à comunicação sem fio presente em tais ambientes. Assim, de acordo com esta abordagem, em caso de erros na transmissão, o escalonador de tráfego poderá gerenciar retransmissões para que os dados perdidos possam ser recuperados. A avaliação da abordagem proposta é realizada através de simulações, onde os algoritmos de retransmissão são aplicados a diferentes cenários, que são abstrações de um ambiente industrial, e os resultados dessa avaliação são obtidos com o auxílio de um simulador de redes desenvolvido e comparados entre si para avaliar qual dos algoritmos possui melhor eficiência em determinada aplicação.
13
  • AGUINALDO BEZERRA BATISTA JÚNIOR
  • Firewall para Protocolos Industriais
  • Advisor : PAULO SERGIO DA MOTTA PIRES
  • COMMITTEE MEMBERS :
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • JORGE DANTAS DE MELO
  • JOSÉ SÉRGIO DA ROCHA NETO
  • PAULO SERGIO DA MOTTA PIRES
  • Data: Jul 6, 2009


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  • A utilização de firewalls é uma abordagem amplamente aceita quando se deseja proteger redes de Tecnologia de Automação (TA) de redes de Tecnologia da Informação (TI). Esta dissertação aborda o desenvolvimento de uma firewall para redes de automação baseadas em TCP/IP que protege dispositivos industriais de tráfego em desconformidade com o tráfego esperado. Todo tráfego de rede que não está de acordo com os padrões de um determinado protocolo industrial ou que não respeitas as limitações impostas é considerado anormal e deve ser bloqueado. Foi desenvolvida uma aplicação em nível de usuário que realiza a filtragem de tráfego sobre a camada de aplicação. O protocolo industrial escolhido como estudo de caso foi o Modbus/TCP, devido à sua simplicidade, documentação abundante e alta relevância em redes industriais.
14
  • WANY LEYDIANE SOUZA DE ANDRADE
  • Estimação de Modelos ARIMA/ARIMAX e Aplicação em Inferência de Perdas de Propano
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • DIEGO RODRIGO CABRAL SILVA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jul 16, 2009


  • Show Abstract
  • Nesta dissertação de mestrado realiza-se um estudo sobre séries temporais, que contém uma descrição das principais técnicas existentes para análise de séries temporais lineares, detalhando-se mais profundamente os modelos ARIMA e ARIMAX. Os modelos ARIMA e ARIMAX destinam-se à modelagem de séries temporais que podem ser representadas por equações lineares, sejam elas estacionárias ou não-estacionárias. Dentro do processo de estimação do modelo ARIMA/ARIMAX, usam-se várias técnicas combinadas, em diferentes partes desse processo, como: Critério de Informação de Akaike para a escolha das ordens e atrasos do modelo e o algoritmo Recursive Least Squares para estimar os coeficientes do modelo. O problema a ser abordado nesta dissertação consiste em, de posse apenas de amostras de uma série temporal no domínio do tempo, e de uma entrada (ou várias) do sistema gerador dessa série temporal, estimar um modelo que represente adequadamente essa série, com o menor erro possível em relação à série real e à série ajustada pelo modelo. Os principais resultados desta dissertação são a implementação e validação de algoritmos para determinação de ordens, coeficientes e atrasos dos modelos ARIMA/ARIMAX. Outro resultado refere-se à estimação do modelo e à realização de inferências para a série temporal do estudo de caso, a série de Perdas de Propano no topo da coluna deetanizadora de uma Unidade de Processamento de Gás Natural. As estimações realizadas sobre a saída da série do estudo de caso funcionarão como um sensor de software capaz de indicar a perda de propano nessa coluna em caso de ausência de um sensor de hardware para tal finalidade.
15
  • ANTONIO HIGOR FREIRE DE MORAIS
  • eOSI: Um modelo para Desenvolvimento de Sistemas Embarcados Tolerantes a Falhas
  • Advisor : GLAUCIO BEZERRA BRANDAO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • GLAUCIO BEZERRA BRANDAO
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Jul 17, 2009


  • Show Abstract
  • A evolução das tecnologias em semicondutores possibilita que dispositivos sejam desenvolvidos cada vez mais com uma maior capacidade de processamento. Neste sentido, estes componentes passam a ter sua utilização ampliada para um maior campo de atuação. Ambientes da indústria petroleira, mineração, automotivos e hospitalares são exemplos de setores que estão utilizando tais dispositivos com maior frequência em seus processos. As atividades que são desenvolvidas por estas indústrias estão diretamente envolvidas com a segurança ambiental e a saúde daqueles que nela trabalham. Desta forma, torna-se mister a utilização de sistemas que sejam dotados de características de segurança extra que possam conferir a estes sistemas maior confiabilidade, segurança e disponibilidade. O modelo de referencia eOSI que será apresentado por esta Dissertação tem por objetivo permitir que estes sistemas sejam desenvolvidos sob uma nova perspectiva que facilite a escolha das estratégias de tolerância a falha a serem empregadas na aplicação. Como forma de validar a utilização deste modelo será apresentada uma arquitetura de suporte que foi desenvolvida em FPGA com base neste modelo.
16
  • RICARDO WENDELL
  • Seleção de Características de Imagem Para Reconhecimento e Classificação em Tempo Real

  • Advisor : AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • COMMITTEE MEMBERS :
  • ALEJANDRO CESAR FRERY ORGAMBIDE
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Jul 29, 2009


  • Show Abstract
  • Neste trabalho, introduzimos melhorias na abordagem de redução de dados e na ex-
    tração e seleção de características visuais com o objetivo principal de melhorar a per-
    formance no processamento de visão de baixo nível visando possibilitar a realização
    de tarefas envolvendo reconhecimento de objetos por plataformas robóticas em tempo
    real. O modelo proposto pode ser aplicado em diversas situações e em ambientes não-
    estruturados, proporcionando funcionalidades requisitadas em uma grande categoria de
    problemas de visão computacional. Discutimos os conceitos e soluções propostos pelo
    modelo, incluindo a organização e estruturação dos algoritmos propostos, apresentando
    implementações realizadas em linguagem C e usando a plataforma Java, demonstrando
    sua aplicabilidade. A validação deste modelo é realizada com experimentos práticos que
    demonstram a redução no tempo de processamento e a capacidade de reconhecimento e
    classificação de objetos utilizando uma rede neural do tipo perceptron em multi-camadas
    treinada com algoritmo Backpropagation. Convém ressaltar que a base deste modelo
    propiciou o desenvolvimento de novas funcionalidades tais como a atenção visual e a
    implementação de uma fóvea móvel para a melhor abstração das informações visuais,
    desenvolvido em outro trabalho paralelo ao nosso.

17
  • RAFAEL BESERRA GOMES
  • Multi-resolução com Fóvea Móvel para Redução e Abstração de Dados em Tempo Real
  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • BRUNO MOTTA DE CARVALHO
  • HERMAN MARTINS GOMES
  • LUIZ EDUARDO CUNHA LEITE
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Aug 7, 2009


  • Show Abstract
  • Nós propomos uma nova abordagem para reduzir e abstrair informações visuais para aplicações de visão robótica. Basicamente, uma fóvea móvel em combinação com uma representação em multi-resolução é criada a partir de um par de imagens, reduzindo a quantidade de informações das imagens originais. Com essa nova abordagem teórica, é possível aplicar diversos filtros, calcular disparidade estéreo e obter análise de movimento em tempo real (pelo menos 30 quadros por segundo). Como principal contribuição, a fóvea móvel permite, na maior parte do tempo, que um robô não necessite realizar movimentação física de dispositivos de forma a ter a região de interesse no centro das imagens. Nós apresentamos a formalização matemática da abordagem com fóvea móvel e os algoritmos. Validamos o modelo proposto com resultados experimentais.
18
  • ANTONIO SALVIO DE ABREU
  • Desenvolvimento de Monopolos Quase-Espirais para Aplicações em Sistemas UWB
  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • LAERCIO MARTINS DE MENDONCA
  • RONALDO DE ANDRADE MARTINS
  • Data: Aug 11, 2009


  • Show Abstract
  • Este trabalho consiste na análise de uma estrutura de antena de microfita projetada para aplicação em sistemas de banda ultra larga (ultra wideband – UWB). Trata-se de um estudo prospectivo e analítico onde são experimentadas as modificações na geometria da antena, observando-se sua adequação aos objetivos propostos. Sabe-se que a antena UWB deve operar numa faixa de no mínimo 500 MHz, e atender uma banda fracionária maior ou igual a 25%. É desejável ainda, que a antena atenda às especificações de faixa determinadas pela FCC – Federal Communication Commission, que em 2002 regulamentou o sistema UWB designando a largura de banda de 7,5 GHz, numa faixa que varia de 3,1 GHz a 10,6 GHz. fixando a densidade espectral de potência máxima de operação em -41,3 dBm/MHz, e definindo a banda fracionária em 20%. O estudo parte de uma estrutura de geometria em forma de @ estilizada, que evolui através de modificações na sua forma, simuladas nos softwares comerciais CST MICROWAVE STUDIO, versão 5.3.1, e, em seguida, testado com o uso do ANSOFT HFSS, versão 9. Variações estas, com base em observações de publicações disponíveis na literatura, referentes a antenas de microfita monopolo planar. Como resultado é proposta uma antena, denominada Antena Monopolo Quase-Espiral Planar Retangular para aplicações em sistemas UWB – AMQEUWB, que apresenta resultados simulados e medidos satisfatórios, coerente com os objetivos do estudo. Algumas propostas para trabalhos futuros estão citadas.
19
  • IRADILSON FERREIRA DA COSTA
  • Antenas e Superfícies Seletivas de Frequência Reconfiguráveis para Sistemas de Comunicação sem Fio
  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • GLAUCO FONTGALLAND
  • RONALDO DE ANDRADE MARTINS
  • SILVIO ERNESTO BARBIN
  • Data: Aug 11, 2009


  • Show Abstract
  • Este trabalho tem como objetivo apresentar como as antenas de microfita e as superfícies seletivas de frequência reconfiguráveis podem ser alternativas para operar em sistemas de comunicação sem fio que necessitem alterar sua frequência de operação de acordo com os requisitos impostos a este sistema ou condições do meio. O propósito central é apresentar uma antena de microfita com patch circular reconfigurável utilizando um anel parasita e uma superfície seletiva de frequência tipo dipolo reconfigurável. Para isto são apresentados temas fundamentais como as antenas de microfita, diodos PIN e a teoria fundamental de operação das antenas e superfícies seletivas de frequência reconfiguráveis. São apresentadas todas as simulações e medições realizadas dos protótipos construídos e é feita uma análise de alguns parâmetros como largura de banda e diagrama de radiação, para as antenas, e características de transmissão, para as superfícies seletivas de frequência. Foram utilizadas fitas de cobre no lugar das chaves para a prova do conceito de reconfigurabilidade.
20
  • DIEGO FERNANDES SALES
  • Análise de Handover inter e intra – célula em um Sistema de Telefonia Celular através de Método de Medição Simplificado
  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • JOABSON NOGUEIRA DE CARVALHO
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • SANDRO GONCALVES DA SILVA
  • Data: Aug 12, 2009


  • Show Abstract
  • Esta dissertação apresenta a aplicação de um aparelho portátil, PlugData MG100G, equipado com um módulo celular, para análise de cobertura de radiofreqüência em uma rede GSM na cidade de João Pessoa - PB em quatro regiões distintas. O equipamento, originalmente, foi criado para uso em ambientes fixos, e para isso, tornou-se necessária sua adaptação para que fosse utilizado em condições de mobilidade. A análise de RF é feita através do Mobile Measurement Reports (MMRs) que são usados com propósitos de avaliar o handover na rede. Por intermédio do Measurement Reports é possível identificar a célula que serve o móvel e uma lista de células vizinhas mais próximas monitoradas pelo próprio móvel. Neste trabalho são analisados apenas os dados referentes à célula servidora e às duas células vizinhas mais próximas. Verificam-se tanto handovers inter– células (entre células) como handovers intra – células (no interior das células). Através dos resultados obtidos pode-se fazer uma análise em relação ao planejamento de freqüências criado para as regiões onde as medidas foram realizadas e à qualidade de serviço oferecida pela rede.
21
  • ROBSON HEBRAICO CIPRIANO MANICOBA
  • Estudo Comparativo de Técnicas de Cascateamento de Superfícies Seletivas em Frequência
  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • GLAUCO FONTGALLAND
  • LAERCIO MARTINS DE MENDONCA
  • Data: Aug 12, 2009


  • Show Abstract
  • Este trabalho apresenta uma análise teórica e numérica do cascateamento de superfícies seletivas de frequência, que usa patches retangulares e fractais de Koch triangular como elementos. Para isto, são utilizadas duas técnicas de cascateamento, visando à determinação das características de transmissão e de reflexão. Superfícies seletivas de frequência abrangem uma grande área das Telecomunicações e têm sido largamente utilizadas devido a seu baixo custo, peso reduzido e habilidade de se integrar com outros circuitos de microondas. Elas são especialmente importantes em diversas aplicações, como aviões, sistemas de antenas, radomes, foguetes, mísseis, etc. Aplicações de FSS em faixas de freqüência elevadas têm sido investigadas, assim como aplicações destas estruturas em cascata ou multicamadas, e FSS ativas. Especificamente, as análises usam a teoria de circuitos de microondas, em conjunto com os harmônicos de Floquet, permite a obtenção das expressões dos parâmetros de espalhamento de cada estrutura e também da estrutura composta por duas ou mais FSS. No trabalho, são apresentados resultados numéricos para as características de transmissão. São feitas comparações com resultados experimentais e também com resultados simulados utilizando o software comercial Ansoft Designer® v3. São apresentadas, ainda, sugestões de continuidade do trabalho.
22
  • LINCOLN MACHADO DE ARAUJO
  • Análise Teórica e Experimental de Antenas Planares e Suas Aplicações em Superfícies Seletivas de Frequência
  • Advisor : ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • COMMITTEE MEMBERS :
  • ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
  • JEFFERSON COSTA E SILVA
  • PAULO HENRIQUE DA FONSECA SILVA
  • RONALDO DE ANDRADE MARTINS
  • Data: Aug 13, 2009


  • Show Abstract
  • Este trabalho apresenta uma análise teórica e numérica de estruturas que utilizam superfícies seletivas de frequência aplicadas a antenas do tipo patch.. Para isso, é utilizado o método FDTD visando determinar os campos refletidos no domínio do tempo. As aplicações das superfícies seletivas de freqüência e antenas patch abrangem uma grande área das Telecomunicações, principalmente em comunicações móveis e vão desde filtros até as antenas banda larga. Especificamente, a análise usa os campos transmitidos e refletidos obtidos no domínio do tempo, em conjunto com transformada de Fourier permitindo a obtenção dos parâmetros de transmissão da antena. A condição de contorno absorvedora utilizada foi a de camada perfeitamente casada (PML), permitindo a determinação numérica dos campos com uma quantidade menor de interferências provenientes de reflexões nos limites do espaço discretizado. São considerados patches retangulares condutores sobre uma camada dielétrica e alimentados por linha de microfita. Foram analisadas superfícies seletivas de frequência periódicas e quase periódicas tanto no plano de terra quanto no plano do próprio patch. E realizada uma revisão bibliográfica a respeito da utilização de superfícies seletivas de frequência em antenas patch. Também são comparados resultados numéricos e medidos para a perda de retorno das estruturas analisadas. São apresentadas, ainda, sugestões de continuidade para este trabalho.
23
  • PLINIO ALTOE COSTA VIEIRA
  • Projeto de um Sistema Emulador de Escoamentos e Vaso de Separação Primária
  • Advisor : FRANCISCO DAS CHAGAS MOTA
  • COMMITTEE MEMBERS :
  • BENNO WALDEMAR ASSMANN
  • FRANCISCO DAS CHAGAS MOTA
  • SERGIO JOSE GONCALVES E SILVA
  • VANJA MARIA DE FRANCA BEZERRA
  • Data: Sep 2, 2009


  • Show Abstract
  • A proposta desse trabalho foi desenvolver uma planta-piloto com o objetivo principal de emular picos de pressão de escoamentos num vaso de separação. Efeito semelhante ao provocado pela produção em forma de golfadas em poços de produção equipados com o método de elevação artificial plunger lift. A motivação para o desenvolvimento do mesmo foi a necessidade de se testar, numa planta em escala menor, uma nova técnica desenvolvida para a estimação da vazão de gás em poços produtores equipados com plunger lift. Para seu desenvolvimento foram realizados estudos sobre dos efeitos dos escoamentos multifásicos, funcionamento de métodos de elevação artificial em poços de plunger lift, dos elementos de instrumentação industrial, válvulas de controle, dimensionamento de vasos separadores e sistemas de medição. A metodologia utilizada foi a definição dos fluxogramas do processo, seus parâmetros e como seriam gerados os efeitos necessários para o sucesso dos experimentos. Assim, foram definidas as válvulas de controle, o dimensionamento e construção dos vasos e a aquisição dos demais equipamentos utilizados. Um dos vasos funciona como reservatório de ar comprimido que, conectado ao vaso de separação, gera pulsos de gás controlados por uma válvula on/off. Com o sistema emulador pronto, foram realizadas diversas experiências de controle, sendo o controle de pressão com geração de picos e medição de vazão a principal experiência, onde se comprovou a eficiência da utilização da planta no problema que a motivou. Concluiu-se que o sistema é capaz de gerar efeitos de escoamentos com picos de pressão num vaso de separação primária. Estudos como a estimação de vazão de gás na saida do vaso e diversos estudos acadêmicos poderão ser feitos e testados numa escala menor sendo aplicados em seguida nas plantas reais, evitando perda de tempo e dinheiro.
24
  • FRANCISCO DE ASSIS BRITO FILHO
  • VCO Banda Larga Integrado para Receptor a Cinco Portas

  • Advisor : FERNANDO RANGEL DE SOUSA
  • COMMITTEE MEMBERS :
  • FERNANDO RANGEL DE SOUSA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • ROBSON NUNES DE LIMA
  • VINCENT PATRICK MARIE BOURGUET
  • Data: Sep 3, 2009


  • Show Abstract
  • Este trabalho apresenta um VCO anel banda-larga para ser utilizado em receptores para Rádio Cognitivo baseados no correlator a cinco portas. Uma arquitetura diferencial de três estágios com porta de transmissão é utilizada como forma de manter uma sintonia linear em larga faixa de frequências, bem como, um baixo ruído de fase. Análises de Monte-Carlo foram feita para avaliar as variações de fase em cada estágio, o que constitui uma figura de mérito importante em receptores baseados no correlator de cinco portas. Observou-se correspondência razoavelmente linear entre tensão de controle e frequência de oscilação na faixa compreendida entre 200 MHz e 1800 MHz. O VCO foi preliminarmente projetado para tecnologia CMOS IBM de 130 nanômetros.

25
  • HAULISSON JODY BATISTA DA COSTA
  • Modelagem em SystemC-AMS de uma plataforma compativel com o sistema de Coleta de dados Brasileiro
  • Advisor : FERNANDO RANGEL DE SOUSA
  • COMMITTEE MEMBERS :
  • DAVID SIMONETTI BARBALHO
  • FERNANDO RANGEL DE SOUSA
  • SEBASTIAN YURI CAVALCANTI CATUNDA
  • Data: Sep 3, 2009


  • Show Abstract
  • A dissertação apresenta os resultados de modelagem e simulação em SystemC-AMS de uma plataforma de identificação compatível com o sistema de Coleta de Dados do INPE. O sistema foi concebido a partir de quatro blocos comportamentais que compreende o modelo orbital do canal, do identificador, do controlador e transmissor. Todos esses modelos foram simulados simultaneamente a fim de especificar os componentes e para obter um banco de testes que guie no projeto da plataforma.
26
  • ADAUTO LUIS TADEO BERNARDES DA FONSECA
  • Metodologia de Verificação Funcional para Circuitos Analógicos

  • Advisor : FERNANDO RANGEL DE SOUSA
  • COMMITTEE MEMBERS :
  • ELMAR UWE KURT MELCHER
  • FERNANDO RANGEL DE SOUSA
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • VINCENT PATRICK MARIE BOURGUET
  • Data: Sep 4, 2009


  • Show Abstract
  • O presente trabalho tem como objetivo desenvolver uma ferramenta de verificação para circuitos analógicos. O principal objetivo desta é aumentar a automação dos processos de verificação. Além disso, proporcionar a construção de um ambiente de verificação capaz de gerar relatórios ao longo deste processo. Esta metodologia é baseada na técnica do Modelo de Ouro, no entanto, ela também propõe uma segunda técnica para verificar o modelo de referência, para se obter resultados mais confiáveis. A metodologia foi utilizada, como estudo de caso, na verificação de um amplificador operacional.


27
  • FABIANO MEDEIROS DE AZEVEDO
  • Proposta de Algoritmo para Detecção de Vazamentos em Oleodutos utilizando Análise Freqüencial de Sinais de Pressão

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • VICENTE DELGADO MOREIRA
  • Data: Oct 23, 2009


  • Show Abstract
  • A detecção de vazamentos em dutos é assunto de grande interesse para empresas que realizam o transporte de petróleo e seus derivados, tendo em vista o crescente rigor da legislação ambiental nos países industrializados e em processo de industrialização. No entanto, as tecnologias existentes hoje ainda não estão plenamente consolidadas e estudos vêm sendo realizados com vistas a atingir maiores níveis de sensibilidade e confiabilidade para a detecção de vazamentos em uma ampla variedade de regimes de escoamento.
       Neste sentido, este estudo apresenta os resultados obtidos com a análise do espectro de freqüência de sinais de pressão de oleodutos em diversas situações de escoamento, tais como escoamento normal, vazamentos, partida e parada de bombas, etc. Os resultados indicam que é possível diferenciar o espectro freqüencial dessas diferentes condições de escoamento, o que permite reconhecer e indicar a ocorrência de vazamentos em dutos transportando fluidos líquidos a partir da monitoração de sua pressão.
       Com base nestes resultados, são propostos um algoritmo para detecção de vazamentos em dutos utilizando a análise freqüencial de sinais de pressão e uma metodologia para sintonia e calibração deste algoritmo. O algoritmo e a metodologia de sintonia propostos são avaliados com dados obtidos a partir de vazamentos reais provocados em dutos transferindo petróleo e água, a fim de avaliar sua sensibilidade, confiabilidade e aplicabilidade para diferentes condições de escoamento.

28
  • MANOEL DO BONFIM LINS DE AQUINO
  • Antena de Microfita com Substrato Metamaterial
  • Advisor : HUMBERTO CESAR CHAVES FERNANDES
  • COMMITTEE MEMBERS :
  • ALFREDO GOMES NETO
  • HUMBERTO CESAR CHAVES FERNANDES
  • LAERCIO MARTINS DE MENDONCA
  • SANDRO GONCALVES DA SILVA
  • Data: Nov 19, 2009


  • Show Abstract
  • Este trabalho apresenta a análise teórica e numérica dos parâmetros de uma antena de microfita tipo patch retangular sobre substrato metamaterial. Para isso, é aplicada a teoria de metamateriais - MTM, em conjunto com o método da Linha de Transmissão Transversa - LTT, para a caracterização das grandezas do substrato e obtenção das equações gerais dos campos eletromagnéticos. É realizado um estudo acerca da teoria de metamateriais com o intuito de obter seus parâmetros construtivos, os mesmos são caracterizados através de tensores permissividade e permeabilidade. Essa teoria é aplicada ao método da Linha de Transmissão Transversa chegando-se às equações gerais para os campos eletromagnéticos da antena. Em seguida são utilizados princípios da teoria eletromagnética para obter-se características como: freqüência de ressonância complexa, diagramas de radiação e largura de banda. São simulados diferentes configurações de metamateriais e antenas com o intuito de miniaturizar as dimensões físicas e aumentar a largura de banda das mesmas, os resultados são apresentados através de gráficos. A análise teórica computacional deste trabalho se mostra precisa, em comparação a outros, podendo ser empregado em dispositivos que utilizem metamateriais como substratos. Ao final são apresentadas conclusões e sugestões para trabalhos futuros.
29
  • GLAUBERTO LEILSON ALVES DE ALBUQUERQUE
  • Construção e Validação de um Receptor de GPS para uso Espacial

  • Advisor : FRANCISCO DAS CHAGAS MOTA
  • COMMITTEE MEMBERS :
  • FRANCISCO DAS CHAGAS MOTA
  • GILVAN LUIZ BORBA
  • JOSE BEZERRA PESSOA FILHO
  • Data: Nov 20, 2009


  • Show Abstract
  • O Sistema de Posicionamento Global, conhecido mundialmente pala sigla GPS, é um
    sistema de radionavegação construído pelos norte-americanos com intenções
    militares, mas que tiveram, com o passar do tempo, muitas aplicações de uso
    civil. No Brasil, além do desenvolvimento de foguetes de sondagem, começam a
    aparecer projetos de construção de microsatélites. Estes veículos denominados
    espaciais ou de alta dinâmica podem, quando em vôo, usufruir do sistema GPS
    para localização autônoma e verificação/controle das suas trajetórias. Apesar
    da enorme disponibilidade de receptores GPS no mercado civil, estes não podem
    ser utilizados em veículos de alta dinâmica, seja por questões ambientais
    (vibrações, temperaturas elevadas, etc.) ou por proteção lógica (via software).
    Os receptores para uso em veículos de alta dinâmica, ou veículos espaciais,
    fazem parte de uma tecnologia restrita a poucos países, que estabelecem regras
    muito rígidas para suas aquisições. O presente projeto objetiva construir e
    validar funcionamento básico deste receptor ao instalá-lo num foguete de
    sondagem e coleta de dados em vôo. O software a ser utilizado no receptor já
    estava disponível em código fonte e testado em uma plataforma de
    desenvolvimento denominada GPS Architect. Vários organismos cooperaram para
    realização projeto: AEB, UFRN, IAE, INPE e CLBI. Após vários passos para
    realização do projeto: definição das condições de funcionamento, escolha e
    aquisição dos componentes eletrônicos, fabricação das placas de circuito
    impresso, montagem e testes de integração; o mesmo foi instalado num foguete de
    sondagem VS30 lançado a partir do Centro de Lançamento da Barreira do Inferno em
    Natal/RN. Apesar da coleta parcial dos dados do receptor, por falha técnica do
    sistema de telemetria do foguete, os resultados obtidos foram suficientes para
    validar o funcionamento do receptor nas condições foram propostas.
30
  • RICARDO BARROS DE MENDONCA
  • Modelagem de Usinas Eólicas através de um Processo de Markov e Técnicas de Confiabilidade para a Estimativa Anual da Energia Produzida

  • Advisor : RICARDO FERREIRA PINHEIRO
  • COMMITTEE MEMBERS :
  • RICARDO FERREIRA PINHEIRO
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • PEDRO ANDRE CARVALHO ROSAS
  • Data: Dec 9, 2009


  • Show Abstract
  • Este trabalho tem por objetivo, utilizar um modelo computacional que considera as características estatísticas da velocidade do vento e as características de confiabilidade de uma turbina eólica, tais como taxas de falha e de reparo, representando a usina eólica por um processo de Markov, para determinação da estimativa anual da energia gerada e compará-la com um caso real. Este modelo também pode ser utilizado em estudos de confiabilidade, além de fornecer alguns indicadores de desempenho, que ajudarão na análise de viabilidade de implantação de uma usina eólica. Para a validação deste modelo, foram feitas simulações utilizando o banco de dados da usina eólica de Macau da PETROBRAS. Os resultados obtidos foram bem próximos do real, confirmando, assim, que o modelo reproduziu com sucesso o comportamento de todos os componentes envolvidos. Finalmente, foi feita uma comparação dos resultados apresentados por este modelo, com o resultado da energia anual estimada considerando a modelagem do comportamento do vento por uma distribuição estatística de Weibull.

31
  • JOSE MACEDO FIRMINO FILHO
  • Implementação e Análise de Desempenho dos Protocolos de Criptografia Neural e Diffie-Hellman em Sistemas RFID Utilizando uma Plataforma Embarcada

  • Advisor : ANA MARIA GUIMARAES GUERREIRO
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • GLAUCIO BEZERRA BRANDAO
  • HELIANA BEZERRA SOARES
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Data: Dec 16, 2009


  • Show Abstract
  • Identificação por rádio freqüência, também chamada de RFID (Radio Frequency Identification), representa uma tecnologia de transmissão de dados sem fio. Estes dados são relacionados principalmente a códigos de identificação. A tecnologia RFID vem apresentando um grande potencial de utilização em setores da automação industrial, residencial e hospitalar. No entanto, estas aplicações podem resultar em riscos a segurança e privacidade dos usuários. Recentemente, pesquisadores vêm apresentando possíveis soluções as ameaças de segurança da tecnologia. Entre estas soluções estão os protocolos de distribuição de chaves criptográficas. O presente trabalho tem como objetivo realizar uma avaliação de desempenho dos protocolos de Criptografia Neural e Diffie-Hellman na geração de chaves em sistemas RFID. Para isso, iremos mensurar o tempo de processamento destes protocolos. Para os testes foi desenvolvido uma plataforma em FPGA (Field-Programmable Gate Array) com o processador embarcado Nios II. Sobre esta plataforma foram utilizados os protocolos de Criptografia Neural e Diffie-Hellman no processo de geração de chaves criptográficas. A metodologia de pesquisa baseia-se na agregação de conhecimento ao desenvolvimento de novos sistemas RFID através de uma análise comparativa entre esses dois protocolos de segurança da informação. As principais contribuições deste trabalho são: avaliação de desempenho dos protocolos (Diffie-Hellman e Criptografia Neural) em uma plataforma embarcada e um levantamento bibliográfico de pesquisas relacionadas à segurança da informação em sistemas RFID. Nos resultados obtidos foi possível observar que o protocolo de Diffie-Hellman é mais apropriado para sistemas RFID.

32
  • BRUNO SIELLY JALES COSTA
  • Ambiente para Desenvolvimento de Aplicações Fuzzy Industriais

     

    Ambiente para Desenvolvimento de Aplicações Fuzzy Industriais
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • JOSE ALVARO DE PAIVA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Dec 22, 2009


  • Show Abstract
  • Este trabalho descreve o design, implementação e aplicação de um sistema para controle de processos industriais, baseado na lógica fuzzy e desenvolvido na linguagem Java, com suporte à comunicação industrial através do protocolo OPC. Além do framework Java, o software é completamente independente de outras plataformas. Ele provê ferramentas amigáveis e funcionais para modelagem, construção e edição de sistemas de inferência fuzzy complexos, e utiliza tais sistemas lógicos no controle de uma grande variedade de processos industriais. Os principais requisitos do sistema desenvolvido devem ser flexibilidade, robustez, confiabilidade e facilidade de expansão.

33
  • ÁLVARO MEDEIROS AVELINO
  • Processamento embarcado aplicado a um sistema de detecção de vazamentos

  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • JOSE ALVARO DE PAIVA
  • JOSE BEZERRA DE MENEZES FILHO
  • Data: Dec 23, 2009


  • Show Abstract
  • Os sistemas embarcados estão amplamente difundidos atualmente. Um exemplo é o
    Digital Signal Processor (DSP), que é um dispositivo com alto poder de processamento.
    A contribuição deste trabalho consiste na implementação em DSP da lógica de um sis-
    tema de detecção de vazamentos em tempo real. Dentre os vários métodos de detecção de
    vazamentos existentes atualmente este trabalho se desenvolve utilizando uma técnica ba-
    seada na análise da pressão no duto e que utiliza Transformada Wavelet e Redes Neurais.
    Nesse contexto o DSP, além de realizar o processamento digital do sinal de pressão, tam-
    bém comunica-se com um Global Positioning System (GPS), que auxilia na localização
    do vazamento e com um sistema supervisório, disponibilizando informações para este.
    Para garantir robustez e confiabilidade na comunicação entre DSP e sistema supervisório
    é utilizado o protocolo Modbus. Como trata-se de uma aplicação de tempo real, uma aten-
    ção especial é dada ao tempo de resposta de cada uma das tarefas realizadas pelo DSP. Os
    testes e simulações de vazamentos foram realizados utilizando a estrutura do Laboratório
    de Avaliação de Medição em Petróleo (LAMP), da Universidade Federal do Rio Grande
    do Norte (UFRN).

Thesis
1
  • FLAVIUS DA LUZ E GORGONIO
  • Uma Arquitetura para Análise de Agrupamentos sobre Bases de Dados Distribuídas Aplicada a Segmentação de Mercado
  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ANNE MAGALY DE PAULA CANUTO
  • GUILHERME DE ALENCAR BARRETO
  • JOSE ALFREDO FERREIRA COSTA
  • PAULO JORGE LEITÃO ADEODATO
  • Data: Mar 6, 2009


  • Show Abstract
  • Mineração de dados pode ser definida como um conjunto de técnicas para a extração de conhecimento e procura de padrões úteis e previamente desconhecidos em grandes volumes de dados multidimensionais. Algoritmos tradicionais de análise de agrupamento, como mapas auto-organizáveis e K-means têm sido largamente utilizados como ferramentas de mineração de dados, com o objetivo de permitir a visualização de dados de elevada dimensionalidade, auxiliando na identificação de agrupamentos de dados com características semelhantes. No entanto, algoritmos tradicionais para análise de dados podem não ser eficientes para algumas aplicações atuais por não considerarem a existência de dados armazenados de forma distribuída. Assim, uma crescente tendência de minerar dados armazenados de forma distribuída tem motivado o surgimento de métodos que permitem analisar cada uma das bases de dados isoladamente e combinar os resultados parciais para obter um resultado final. Este trabalho apresenta uma arquitetura para análise de agrupamentos em bases de dados distribuídas, a partir da utilização de algoritmos tradicionais, que reduz sensivelmente a quantidade de dados transferidos entre as unidades remotas e a unidade central. A arquitetura é composta por uma estratégia, baseada em quantização vetorial, que possibilita extrair um conjunto de representantes a partir de partições horizontais e/ou verticais da base de dados, a fim de se obter visões parciais dos agrupamentos existentes em cada um dos conjuntos de dados locais. Posteriormente, os representantes de cada unidade local são enviados à unidade central, que efetua a combinação dos resultados parciais através de um processo de agrupamento sobre os representantes dos dados. Os resultados experimentais obtidos com a utilização da arquitetura proposta sobre diferentes conjuntos de dados demonstram que essa estratégia consegue obter resultados com mesma eficácia que os obtidos com as técnicas de mineração de dados convencionais, onde todas as bases de dados são transferidas para uma unidade central durante a etapa de pré-processamento.
2
  • ALZIRA FERREIRA DA SILVA
  • RoboEduc: Uma Metodologia de Aprendizado com Robótica Educacional
  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • JOAO VILHETE VIEGAS DABREU
  • LUIZ MARCOS GARCIA GONCALVES
  • MARIA DAS GRAÇAS GALVÃO PINTO COELHO
  • SILVIA SILVA DA COSTA BOTELHO
  • Data: Mar 16, 2009


  • Show Abstract
  • Propomos uma metodologia de ensino-aprendizagem com base na teoria sócio-histórica de Vygostky para uso da robótica em escolas do Ensino Fundamental. Buscando ampliar o leque de aplicação da robótica na educação, o tema deste trabalho é o uso de robôs como mediadores no processo ensino-aprendizagem. O objetivo prático é fazer experiências em escolas do ensino fundamental, com robôs sendo construídos, programados e controlados por crianças na faixa etária de seis a dez anos. Nossa proposta situa-se na área de pesquisa denominada de Robótica Educacional (ou Pedagógica), que busca utilizar a robótica como instrumento no combate da exclusão digital e tecnológica. Basicamente, analisamos como as crianças resolvem problemas contextualizados com a utilização de robôs. A partir dessas situações, podemos verificar que as interações entre os integrantes de cada grupo crescem à medida que as oficinas se desenvolvem. Isto reforça o modelo de aprendizado de Vigotsky, baseado na teoria sócio-interacionista. As oficinas realizadas são um meio efetivo e promissor para desenvolvimento de projetos de Inclusão Digital e Tecnológica.
3
  • DENNIS BARRIOS ARANIBAR
  • Aprendizado por Reforço com Valores de Influência em Sistemas Multi-agentes
  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ALEXANDRE DA SILVA SIMÕES
  • ANNE MAGALY DE PAULA CANUTO
  • JORGE DANTAS DE MELO
  • LUIZ MARCOS GARCIA GONCALVES
  • RICARDO CORDEIRO DE FARIAS
  • Data: Mar 19, 2009


  • Show Abstract
  • Neste trabalho, propomos um novo paradigma de aprendizado coletivo baseado em retornos fornecidos por vários agentes que tentam realizar uma tarefa sobre um mesmo ambiente. O paradigma é apresentado na forma do algoritmo de aprendizado por reforço e o denominamos de aprendizado por reforço com valores de influência. Este novo paradigma é de certa forma inspirado nas interações sociais entre pessoas, onde as opiniões de uns influenciam nas decisões dos outros. Com base no modelo proposto foi criado o algoritmo IVQ-Learning o qual depois de ser testado em jogos repetitivos, e jogos estocásticos simples, se mostrou como uma boa opção na tentativa de obter algoritmos que garantam a convergência para o equilíbrio de Nash ótimo em problemas cooperativos. Assim, estes resultados nos encorajam a continuar com a presente pesquisa, de forma a modelar completamente o paradigma e definir a influência dos seus parâmetros no processo de aprendizado. Pretendemos aplicar este paradigma ao problema de geração de mapas de ambientes de forma cooperativa, e é importante observar que, a luz da bibliografia estudada, este problema ainda não foi abordado com a utilização de agentes com capacidade de aprender.
4
  • FRANCISCO CHAGAS DE LIMA JUNIOR
  • Algoritmo Q-Learning como Estratégia de Exploração e/ou Explotação para as Metaheurísticas GRASP e Algoritmo Genético
  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • CARLOS HENRIQUE COSTA RIBEIRO
  • DARIO JOSE ALOISE
  • GERARDO VALDISIO RODRIGUES VIANA
  • JORGE DANTAS DE MELO
  • Data: Mar 20, 2009


  • Show Abstract
  • Técnicas de otimização conhecidas como metaheurísticas têm obtido sucesso na resolução de problemas classificados como NP - Árduos. Estes métodos utilizam abordagens não determinísticas que geram soluções próximas do ótimo sem, no entanto, garantir a determinação do ótimo global. Além das dificuldades inerentes à complexidade que caracteriza os problemas de otimização, as metaheurísticas enfrentam ainda o dilema de exploração/explotação, que consiste em escolher entre intensificação da busca em uma região específica e a exploração mais ampla do espaço de soluções. Uma forma de orientar tais algoritmos em busca de melhores soluções é supri-los de maior conhecimento do problema através da utilização de um agente inteligente, capaz de reconhecer regiões promissoras e/ou identificar em que momento deverá diversificar a direção de busca, isto pode ser feito através da aplicação de Aprendizagem por Reforço. Neste contexto, este trabalho propõe o uso de uma técnica de Aprendizagem por Reforço - especificamente o Algoritmo Q-learning - como uma estratégia de exploração/explotação para as metaheurísticas GRASP (Greedy Randomized Adaptive Search Procedure) e Algoritmo Genético. Na implementação da metaheurística GRASP proposta, utilizou-se o Q-learning em substituição ao algoritmo guloso-aleatório tradicionalmente usado na fase de construção. Tal substituição teve como objetivo melhorar a qualidade das soluções iniciais que serão utilizadas na fase de busca local do GRASP, e, ao mesmo tempo, suprir esta metaheurísticas de um mecanismo de memória adaptativa que permita a reutilização de boas decisões tomadas em iterações passadas e que evite a repetição de decisões não promissoras. No Algoritmo Genético, o algoritmo Q-learning foi utilizado para gerar uma população inicial de alta aptidão, e após um determinado número de gerações, caso a taxa de diversidade da população seja menor do que um determinado limite L, ele é também utilizado em uma forma alternativa de operador de cruzamento. Outra modificação importante no algoritmo genético híbrido é a proposta de um processo de interação mutuamente cooperativa entre o os operadores genéticos e o Algoritmo Q-learning. Neste processo interativo/cooperativo o algoritmo Q-learning recebe uma atualização adicional na matriz dos Q-valores com base na solução elite da população corrente. Os experimentos computacionais apresentados neste trabalho consistem em comparar os resultados obtidos com a implementação de versões tradicionais das metaheurísticas citadas, com aqueles obtidos utilizando os métodos híbridos propostos. Ambos os algoritmos foram aplicados com sucesso ao problema do caixeiro viajante simétrico, que por sua vez, foi modelado como um processo de decisão de Markov.
5
  • RAQUEL ESPERANZA PATIÑO ESCARCINA
  • Seleção Seqüencial de Descritores por análise da Semântica para Recuperação de Imagens Baseada no Conteúdo
  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • AARAO LYRA
  • ADILSON GONZAGA
  • JOSE ALFREDO FERREIRA COSTA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Mar 20, 2009


  • Show Abstract
  • Com o crescimento acelerado dos bancos de dados de diversos tipos (texto, multimí- dia, etc.), é visto que existe uma necessidade de propor métodos que permitam ordenar, acessar e recuperar os dados de forma simples e rápida. Os bancos de dados de imagens além de ter estas necessidades, requerem de uma representação das imagens de forma que as características de conteúdo semântico sejam consideradas. Neste sentido, diversas propostas tais como a recuperação baseada em anotações textuais vem sendo feitas. Na proposta com anotações, a recuperação é baseada na comparação entre a descrição textual que um usuário possa fazer da imagem e as descrições das imagens armazenadas no banco de dados. Entre suas desvantagens vemos que a descrição textual é muito dependente do observador, além do esforço computacional requerido para descrever todas as imagens no banco de dados. Uma outra proposta é a recuperação baseada no conteúdo - CBIR, onde cada imagem é representada pelas suas características de baixo nível como são: cor, forma, textura, etc. Neste sentido, os resultados na área de CBIR tem-se mostrado muito promissores. porém, a representação da semântica das imagens por caracter ísticas de baixo nível é um problema em aberto. Novos algoritmos para a extração de características assim como novos métodos de indexação tem sido propostos na literatura. Porém, estes algoritmos tornam-se cada vez mais complexos. Logo, fazendo uma análise, é natural perguntar se existe uma relação entre a semântica e as características de baixo nível extraídas em uma imagem? e se existe uma relação, quais descritores a representam melhor? o que nos leva a uma nova pergunta: quantos descritores usar para a representação do conteúdo das imagens?. O trabalho apresentado nesta tese, propõe um método para analisar a relação que existe entre descritores de baixo nível e a semântica, na tentativa de responder às perguntas formuladas. Ainda, observou-se que em relação as formas de indexar as imagens existem três possibilidades: Usando vetores característicos compostos, usando estruturas de indexação independentes e paralelas para cada descritor ou conjunto deles e usando vetores característicos ordenados em forma seqüencial. Assim, as duas primeiras formas foram amplamente estudadas e aplicadas na literatura, porém não se encontraram registros da terceira forma ter sequer sido explorada. Então nesta tese propõe-se também indexar usando uma estrutura seqüencial dos descritores e ainda, a ordem destes descritores deve estar baseada na relação que existe entre cada descritor e a semântica dos usuários. Finalmente, a proposta de indexação realizada nesta tese se mostrou superior às propostas tradicionais e ainda, mostrou-se experimentalmente que a ordem nesta seqüência é relevante e existe uma relação direta entre esta ordem e a relação dos descritores de baixo nível com a semântica dos usuários.
6
  • DANIELLE SIMONE DA SILVA CASILLO
  • Controle Preditivo Não Linear Baseado no Modelo de Hammerstein com Prova de Estabilidade
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ADHEMAR DE BARROS FONTES
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OSCAR GABRIEL FILHO
  • OTACILIO DA MOTA ALMEIDA
  • Data: Mar 27, 2009


  • Show Abstract
  • O Controle Preditivo tem recebido muita atenção nas últimas décadas, visto que a necessidade de compreender, analisar, predizer e controlar sistemas reais tem crescido rapidamente com o avanço tecnológico e industrial. O objetivo desta tese é apresentar uma contribuição para o desenvolvimento e implementação de Controladores Preditivos Não lineares baseado no modelo de Hammerstein, bem como fazer uma avaliação de suas propriedades. Neste caso, no desenvolvimento do Controlador Preditivo Não Linear utiliza-se o método de linearização por degrau de tempo e é introduzido um termo de compensação a fim de melhorar o desempenho do mesmo. A principal motivação desta tese é o estudo e a prova da estabilidade para o Controlador Preditivo Não Linear baseado no modelo de Hammerstein. Para isso utilizou-se os conceitos de setores e Critério de Popov. Testes de simulação com modelos da literatura mostram que as abordagens propostas são capazes de controlar com um bom desempenho e garantir a estabilidade dos sistemas.
7
  • ROMMEL WLADIMIR DE LIMA
  • Mapa de Conteúdos e Mapa de Dependências: Ferramentas Pedagógicas para uma Metodologia de Planejamento baseada em Objetivos Educacionais e sua Implementação em um Ambiente Virtual de Aprendizagem
  • Advisor : SERGIO VIANNA FIALHO
  • COMMITTEE MEMBERS :
  • APUENA VIEIRA GOMES
  • ARNON ALBERTO MASCARENHAS DE ANDRADE
  • FRANCISCO MILTON MENDES NETO
  • MARIA ELIZABETH SUCUPIRA FURTADO
  • SERGIO VIANNA FIALHO
  • Data: Jun 1, 2009


  • Show Abstract
  • Com a expansão da Educação a Distância, promovida principalmente pelos novos recursos tecnológicos, existe atualmente uma procura por ferramentas e metodologias que possibilitem trabalhar o ensino-aprendizagem, de acordo com teorias pedagógicas consolidadas e que possam ser inseridas nos Ambientes Virtuais de Aprendizagem. O objetivo deste trabalho é apresentar uma metodologia de planejamento, baseada em teorias pedagógicas já comprovadas, e que contribua para a inserção da avaliação no processo de ensino-aprendizagem. Para isso foi realizado uma revisão da literatura para identificação dos conceitos pedagógicos necessários à definição da metodologia e utilizado um método descritivo no estabelecimento das relações existentes entre esses conceitos e a Educação a Distância. Como resultado desse processo, foram especificados e implementados o Mapa de Conteúdos e o Mapa de Dependências, duas ferramentas pedagógicas que promovem o planejamento de uma disciplina e possibilitam pensar a avaliação ainda nessa fase. Implementadas no Moodle, as ferramentas desenvolvidas foram testadas em uma disciplina a distância para observação, na prática, dos conceitos implementados. Com isso, foi possível verificar que a metodologia de planejamento proposta, através das ferramentas desenvolvidas, auxilia no planejamento da disciplina e no processo de avaliação do aluno, contribuindo para inserção da avaliação no processo de ensino-aprendizagem e colocando o aluno como elemento central desse processo.
8
  • ROQUE MENDES PRADO TRINDADE
  • Uma Fundamentação Matemática para Processamento Digital de Sinais Intervalares
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • AARAO LYRA
  • ADRIAO DUARTE DORIA NETO
  • BENEDITO MELO ACIOLY
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • RENATA HAX SANDER REISER
  • ROBERTO CALLEJAS BEDREGAL
  • Data: Jun 5, 2009


  • Show Abstract
  • Este trabalho explora uma fundamentação matemática, para o processamento digital de sinais sob uma óptica da matemática intervalar. Pretende explorar o problema aberto de precisão e de representação de dados em sistemas digitais, trabalhando com uma versão intervalar de representação de sinais. Processamento de sinais é uma área muito rica e complexa, por isso, faremos um recorte e focaremos em sistemas lineares invariantes no tempo. Existe uma vasta literatura na área, mas mesmo assim, ainda existe alguns conceitos na matemática intervalar que precisam ser redefinidos ou elaborados para a construção de uma teoria sólida de processamento de sinais intervalares. Construiremos os fundamentos básicos para processamentos de sinais na versão intervalar, tais como as propriedades básicas linearidade, estabilidade, causalidade, uma versão intervalar de sistemas lineares e suas propriedades. Serão apresentadas versões intervalares da convolução e da transformada Z. Será feita análise de convergências de sistemas usando a transformada Z intervalar, uma distância essencialmente intervalar, números complexos intervalares, aplicação em um filtro intervalar.
9
  • RAIMUNDO SANTOS MOURA
  • Metodologia para Modelagem, Validação e Programação de Controladores Lógicos Industriais Usando Statecharts Básicos
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ANDRE LAURINDO MAITELLI
  • CARLOS EDUARDO TRABUCO DOREA
  • PAULO ROMERO MARTINS MACIEL
  • Data: Jun 9, 2009


  • Show Abstract
  • Apesar de muitos estudos tentarem desenvolver métodos ``amigáveis'' para programação de controladores lógicos industriais, estes ainda são programados através de métodos convencionais no estilo tentativa e erro e, na prática, usualmente não existe documentação escrita para esses sistemas. A solução ideal seria usar um ambiente computacional que permita engenheiros industriais implementar o sistema usando linguagens de alto nível e que obedeçam padrões internacionais. Baseado nessa perspectiva, este trabalho propõe um procedimento sistemático para modelar a planta e o controle de sistemas com dinâmica discreta que incluem operações sequenciais, paralelas e temporizadas, usando um formalismo baseado nos Statecharts, denominado Statecharts Básicos (SCB). A metodologia também permite procedimentos automáticos de validação e implementação desses sistemas. Inicialmente, descreve-se a realidade atual da área de automação industrial e apresenta-se os principais formalismos usados no processo de modelagem e síntese de controladores industriais, a saber: autômatos, teoria de controle supervisório, redes de Petri e os diagramas Statecharts. Em seguida, define-se a sintaxe e a semântica formal dos SCB e, posteriormente, descreve-se a metodologia proposta nesta Tese, que inclui a modelagem da planta e do programa de controle, a validação do modelo completo (controle+planta), bem como o algoritmo para traduzir o modelo do controle para a linguagem Ladder. Por fim, dois exemplos típicos de aplicações da área de manufatura são discutidos como estudos de casos para validar a proposta.
10
  • DANNIEL CAVALCANTE LOPES
  • Implementação e Avaliação de Máquinas de Comitê em um Ambiente com Múltiplos Processadores Embarcados em um Único Chip
  • Advisor : JORGE DANTAS DE MELO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANA MARIA GUIMARAES GUERREIRO
  • JORGE DANTAS DE MELO
  • JOSE ALBERTO NICOLAU DE OLIVEIRA
  • MANOEL EUSEBIO DE LIMA
  • PEDRO FERNANDES RIBEIRO NETO
  • Data: Jul 30, 2009


  • Show Abstract
  • O número de aplicações baseadas em sistemas embarcados cresce significativamente a cada ano. Isso se deve ao fato que apesar de sistemas embarcados possuírem restrições e unidades de processamento simples, o desempenho dessas tem melhorado a cada dia. Entretanto a complexidade das aplicações também cresce, fazendo com que sempre exista a necessidade de um desempenho melhor. Portanto apesar dessa evolução, existem casos, nos quais, um sistema embarcado com uma única unidade de processamento não é suficiente para realizar o processamento das informações em tempo hábil. Para melhorar o desempenho destes sistemas, pode-se analisar a implementação de soluções com processamento paralelo e assim utilizar-los em aplicações mais complexas que exigem um alto desempenho. A idéia é avançar além das aplicações que já utilizam sistemas embarcados, explorando a utilização de um conjunto de unidades de processamento cooperando entre si para execução de um algoritmo inteligente. O número de trabalhos existentes nas áreas de processamento paralelo, sistemas inteligentes e sistemas embarcados é grande. Entretanto trabalhos que unam essas três áreas para a solução de algum tipo de problema, são reduzidos. Diante deste contexto, esse trabalho teve como objetivo utilizar ferramentas disponíveis para arquiteturas FPGA, desenvolvendo uma plataforma com múltiplos processadores para utilização em problemas de processamento inteligente com redes neurais artificiais.
11
  • ALEXANDRE MAGNUS FERNANDES GUIMARAES
  • Desenvolvimento de um Sistema de Automação para uma Planta de Inertização de Resíduos por Plasma
  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRES ORTIZ SALAZAR
  • ANDRE LAURINDO MAITELLI
  • JOSSANA MARIA DE SOUZA FERREIRA
  • ANTONIO RAMIREZ HIDALGO
  • OTACILIO DA MOTA ALMEIDA
  • Data: Aug 28, 2009


  • Show Abstract
  • Os processos tradicionais de tratamento de resíduos perigosos são questionáveis por gerar outros resíduos que afetam negativamente à saúde das pessoas. Como tentativa de minimização desses problemas foi desenvolvido um sistema de tratamento de resíduos perigosos por plasma térmico, uma tecnologia adequada por produzir altas temperaturas, impedindo a formação de poluentes bastantes tóxicos ao homem. Uma planta de tratamento de resíduos perigosos por plasma térmico foi desenvolvida, e o trabalho aqui exposto traz uma solução de controle e automação para essa planta, com a aplicação de dispositivos e técnicas de controle modernos. O sistema dispõe de recursos de monitoramento e proteções local e remoto que garantem a segurança do processo e dos operadores. Para controle de temperatura do reator principal da planta foi dada uma atenção especial por ser o recinto onde ocorre o principal processamento e por apresentar um complexo modelo matemático. Para esse fim, foram empregados controles em cascata baseados em lógica Fuzzy. O elemento central de gerenciamento da automação e controle da planta fica a cargo de um módulo CLP compacto. Um computador de processo, com uma interface homem-máquina específica, disponibiliza ao operador informações e controles da planta.
12
  • ROSSANA MORENO SANTA CRUZ
  • Análise e Otimização de Superfícies Seletivas de Frequência Utilizando Redes Neurais Artificiais e Algoritmos de Otimização Natural
  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • FLAVIO JOSE VIEIRA HASSELMANN
  • GERVASIO PROTASIO DOS SANTOS CAVALCANTE
  • LUIZ ALENCAR REIS DA SILVA MELLO
  • MARIA ROSA MEDEIROS LINS DE ALBUQUERQUE
  • PAULO HENRIQUE DA FONSECA SILVA
  • Data: Sep 28, 2009


  • Show Abstract
  • As estruturas planares periódicas bidimensionais, conhecidas como Superfícies Seletivas de Frequência, têm sido bastante estudadas por causa da propriedade de filtragem de frequência que apresentam. Similares aos filtros que operam na faixa tradicional de radiofrequência, tais estruturas podem apresentar características espectrais de filtros rejeita-faixa ou passa-faixa, dependendo do tipo de elemento do arranjo (patch ou abertura, respectivamente) e podem ser utilizadas em uma variedade de aplicações, tais como radomes, refletores dicróicos, filtros de micro-ondas, condutores magnéticos artificiais, absorvedores etc. Para aumentar o desempenho de tais dispositivos eletromagnéticos e investigar suas propriedades, muitos estudiosos têm analisado vários tipos de estruturas periódicas: superfícies seletivas de frequência reconfiguráveis, filtros de múltiplas camadas seletivas, além de arranjos periódicos impressos sobre substratos dielétricos anisotrópicos e que utilizam geometrias fractais na sua formação. Em geral, não existe uma solução analítica diretamente extraída a partir da resposta em frequência de um dispositivo; desta forma, a análise de suas características espectrais requer a aplicação de técnicas de onda completa rigorosas, como o método da equação integral, por exemplo. Além disso, devido à complexidade computacional exigida para a implementação destes métodos, muitos estudiosos ainda utilizam a investigação por tentativa e erro, para alcançar critérios satisfatórios ao projeto dos dispositivos. Como este procedimento é muito trabalhoso e dependente do homem, faz-se necessário o emprego de técnicas de otimização que acelerem a obtenção de estruturas periódicas com especificações de filtragem desejadas. Alguns autores têm utilizado redes neurais artificiais e algoritmos de otimização natural, como os algoritmos genéticos e a otimização por enxame de partículas no projeto e otimização das superfícies seletivas de frequência. Este trabalho tem como objetivo realizar um estudo mais aprofundado sobre o comportamento eletromagnético das estruturas periódicas seletivas de frequência, possibilitando a obtenção de dispositivos eficientes e aplicáveis na faixa de micro-ondas. Para isto, redes neurais artificiais são utilizadas em conjunto com técnicas de otimização baseadas na natureza, permitindo a investigação precisa e eficiente de vários tipos de superfícies seletivas de frequência, de forma simples e rápida, tornando-se, portanto, uma poderosa ferramenta de projeto e otimização de tais estruturas.
13
  • KELSON ROMULO TEIXEIRA AIRES
  • ŽSegmentação de Planos Baseada em Homografia Afim, Fluxo Óptico e Reconstrução Métrica
  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • BRUNO MOTTA DE CARVALHO
  • EDUARDO OLIVEIRA FREIRE
  • GUILHERME DE ALENCAR BARRETO
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Oct 5, 2009


  • Show Abstract
  • Planos são importantes componentes geométricos e podem ser utilizados em uma larga variedade de tarefas de visão como reconstrução de cenas e navegação de robôs. É proposto neste trabalho um sistema de segmentação de planos baseado no cálculo de homografias, na estimação do fluxo óptico e na reconstrução métrica. Primeiramente, usando duas imagens de uma sequência monocular, um conjunto de pares de pontos de interesse correspondentes é obtido. Um algoritmo foi desenvolvido para agrupar pontos de interesse pertencentes ao mesmo plano baseado no erro de reprojeção da homografia afim. Em seguida, a informação do fluxo óptico estimado é utilizada na expansão dos planos detectados. Um novo método de estimação de fluxo óptico baseado na informação de cor é proposto. O próximo passo consiste na extração da geometria epipolar da cena. A matriz fundamental é estimada utilizando um procedimento iterativo para descartar correspondências espúrias. Assumindo o sistema calibrado a priori, as matrizes da câmera são computadas a partir da matriz essencial. Finalmente, os pontos são triangulados e a reconstrução métrica dos principais planos da cena é obtida. Testes foram executados em diferentes sequências de imagens capturadas em ambientes internos e externos, e os resultados são apresentados e discutidos.
14
  • VINICIUS PONTE MACHADO
  • Uma Arquitetura MultiAgente aplicada a Redes Industriais Foundation FieldBus para Alocação Dinâmica de Aplicações Inteligentes baseadas em Blocos Funcionais Padrão

  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DENNIS BRANDAO
  • JOAO JOSE VASCO PEIXOTO FURTADO
  • JORGE DANTAS DE MELO
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Dec 11, 2009


  • Show Abstract
  • A automação industrial está diretamente ligada ao crescimento da tecnologia da informação. Tanto as melhorias em soluções de hardware quanto o aprimoramento em metodologias de desenvolvimento de software propiciaram o crescimento do controle do processo produtivo ao longo dos anos. Nesta tese, propomos uma arquitetura que permitirá a união de duas tecnologias no âmbito de hardware (redes industriais) e software (sistemas multiagente). O objetivo de nossa proposta é unir essas tecnologias em uma arquitetura multiagente para permitir implementação de aplicações inteligentes nos dispositivos de campo. Com isso pretendemos fazer que os agentes possam detectar e apontar soluções para problemas encontrados no ambiente de rede industrial. Este trabalho ainda alia a aprendizagem de máquina ao contexto industrial, permitindo dessa forma que a arquitetura de agentes proposta possa se tornar adaptável a um contexto de produção desconhecido ou inesperado. Para isso, utilizamos redes neurais e mostramos uma estratégia para alocação destas redes em dispositivos da rede industrial. Pretendemos assim viabilizar uma melhoria no suporte a decisão em ocorrências no nível de planta auxiliando os operadores na detecção e correção de problemas e falhas.

2008
Dissertations
1
  • RICARDO DE SOUSA BRITTO
  • Uma Arquitetura Distribuída de Hardware e Software para Controle de um Robô Móvel Autônomo
  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • PABLO JAVIER ALSINA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: Jan 25, 2008


  • Show Abstract
  • Neste trabalho é apresentada uma arquitetura de hardware e software para controle do robô móvel autônomo Kapeck. O hardware do robô Kapeck é composto por um conjunto de sensores e atuadores organizados em um barramento de comunicação CAN. Dois computadores embarcados e oito placas microcontroladas foram utilizadas no sistema. Um dos computadores foi utilizado para o sistema de visão, devido à grande necessidade de processamento deste tipo de sistema. O outro computador foi utilizado para coordenar e acessar o barramento CAN e realizar as outras atividades do robô. Placas microcontroladas foram utilizadas nos sensores e atuadores. O robô possui esta configuração distribuída para um bom desempenho em tempo-real, onde os tempos de resposta e a previsibilidade temporal do sistema são importantes. Foi seguido o paradigma híbrido deliberativo-reativo para desenvolver a arquitetura proposta, devido à necessidade de aliar o comportamento reativo da rede de sensores-atuadores com as atividades deliberativas necessárias para realizar tarefas mais complexas.
2
  • ANDERSON ABNER DE SANTANA SOUZA
  • Mapeamento Com Sonar Usando Grade de Ocupação Baseado em Modelagem Probabilística
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • Data: Feb 14, 2008


  • Show Abstract
  • Neste trabalho, propomos um método de mapeamento probabilístico com a representação do ambiente mapeado em uma grade de ocupação modificada. A idéia principal do método proposto é deixar que um robô móvel construa de forma sistemática e incremental a geometria do seu entorno, obtendo ao final um mapa completo do ambiente. Como conseqüência, o robô poderá locomover-se no seu ambiente de modo seguro, baseando-se em um índice de confiabilidade dos dados colhidos do seu sistema perceptivo. O mapa é representado de forma coerente com os dados sensoriais, sejam esses ruidosos ou não, oriundos dos sensores externoceptivos e proprioceptivos do robô. Os ruídos característicos incorporados nos dados de tais sensores são tratados por modelagem probabilística, de modo que seus efeitos possam ser visíveis no resultado final do processo de mapeamento. Os resultados dos experimentos realizados, mostrados no presente trabalho, indicam a viabilidade desta metodologia e sua aplicabilidade na área da robótica móvel autônoma, sendo assim uma contribuição para a área.
3
  • RUMMENIGGE RUDSON DANTAS
  • Interpercepção: Uma Arquitetura de Software Para Compartilhamento de Ambientes Virtuais com Interfaces Gráficas Distintas
  • COMMITTEE MEMBERS :
  • JAUVANE CAVALCANTE DE OLIVEIRA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • Data: Feb 15, 2008


  • Show Abstract
  • Neste trabalho, é apresentado o paradigma Interperceptivo, uma nova abordagem que inclui um conjunto de regras e uma arquitetura de software que une usuários de interfaces diferentes no mesmo ambiente virtual. O sistema detecta os recursos do usuário e realiza transformações nos dados para sua visualização nas interfaces 3D, 2D e textual (1D). Isto permite que qualquer usuário conecte, acesse todas as informações, e troque informações com os outros usuários de um modo flexível, sem necessitar de alterações no hardware e sofware. Como resultados são apresentados dois ambientes virtuais construídos segundo este paradigma.
4
  • FRANCISCO CANINDE HOLANDA DE QUEIROZ
  • CONTROLE VETORIAL DE VELOCIDADE DE UM MOTOR DE INDUÇÃO TRIFÁSICO COM ESTIMAÇÃO NEURAL DE FLUXO
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • JOSSANA MARIA DE SOUZA FERREIRA
  • RICARDO FERREIRA PINHEIRO
  • Data: Mar 17, 2008


  • Show Abstract
  • Este trabalho descreve o estudo e a implementação de um controle vetorial de velocidade para um motor de indução trifásico de 1.1 kW / 4 pólos utilizando estimação neural de fluxo do rotor. O controle vetorial de velocidade opera em conjunto com o controle das correntes nos enrolamentos de cada fase do estator. A estimação neural de fluxo aplicada ao controle vetorial de velocidade tem como objetivo compensar a dependência dos estimadores convencionais em relação às variações nos parâmetros da máquina devido a aumentos de temperatura ou saturação magnética do rotor. O sistema de controle implementado possibilita uma comparação direta dos respectivos desempenhos de velocidade sob orientação do estimador neural em relação ao estimador convencional de fluxo. Todo o controle do sistema é realizado por um programa desenvolvido em linguagem padrão ANSI C. Os principais recursos do DSP utilizados pelo sistema são, respectivamente, os canais de conversão A/D, as saídas PWM e as interfaces paralela e serial RS-232, as quais são responsáveis, respectivamente, pela programação do DSP e a captura de dados através de um sistema de supervisão.
5
  • SERGIO PINHEIRO DOS SANTOS
  • Aplicação de sistemas multiclassificadores no diagnóstico de falhas de motores de indução trifásicos.
  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • PABLO JAVIER ALSINA
  • JÉS DE JESUS FIAIS CERQUEIRA
  • Data: Apr 11, 2008


  • Show Abstract
  • xxxx
6
  • SERGIO PINHEIRO DOS SANTOS
  • Aplicação de sistemas multiclassificadores no diagnóstico de falhas de motores de indução trifásicos.
  • Advisor : JOSE ALFREDO FERREIRA COSTA
  • COMMITTEE MEMBERS :
  • JOSE ALFREDO FERREIRA COSTA
  • JÉS DE JESUS FIAIS CERQUEIRA
  • PABLO JAVIER ALSINA
  • Data: Apr 11, 2008


  • Show Abstract
  • xxxx
7
  • GUTEMBERG SANTOS SANTIAGO
  • Navegação cooperativa de um robô humanóide e de um robô com rodas usando informação visual
  • Advisor : ADELARDO ADELINO DANTAS DE MEDEIROS
  • COMMITTEE MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • PABLO JAVIER ALSINA
  • DIOGO PINHEIRO FERNANDES PEDROSA
  • Data: May 30, 2008


  • Show Abstract
  • xxx
8
  • VIVIANE GURGEL DE CASTRO
  • RoboEduc: Especificação de um Software Educacional para Ensino da Robótica às Crianças como uma Ferramenta de Inclusão Digital.
  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • GLAUCIO BEZERRA BRANDAO
  • LUCIANE TERRA DOS SANTOS GARCIA
  • LUIZ MARCOS GARCIA GONCALVES
  • TATIANA AIRES TAVARES
  • Data: Aug 4, 2008


  • Show Abstract
  • Devido ao problema da exclusão social no Brasil e tendo como foco a inclusão digital, iniciou-se, na Universidade Federal do Rio Grande do Norte, um projeto que pudesse tratar ao mesmo tempo de conceitos de aprendizagem colaborativa e de robótica educacional, voltado a crianças digitalmente excluídas. Dentro deste contexto, foi criada uma metodologia onde são abordados assuntos que vão desde elementos tecnológicos, como informática e robótica, até as disciplinas curriculares como português, matemática, geografia e história, colocadas em situações do dia a dia. São também observados os conceitos pedagógicos de aprendizagem colaborativa e o desenvolvimento das capacidades desses alunos como trabalho em grupo, conhecimento lógico e capacidade de aprendizado. Esta dissertação propõe um software educacional para ensino da robótica denominado RoboEduc, criado para ser utilizado por crianças digitalmente excluídas do ensino fundamental. Sua implementação prioriza uma interface amigável, podendo ser ensinados conceitos de robótica e programação, de uma maneira inovadora, fácil e divertida. Com essa nova ferramenta, usuários sem conhecimento prévio algum de informática ou robótica são capazes de controlar um robô, previamente montado com os kits Lego, ou até programá-lo para realizar determinadas tarefas. A presente dissertação provê a implementação da versão 2 do software. Essa versão apresenta o controle do robô já utilizado. Posteriormente foram implementadaos os diferentes níveis de programação ligados aos diversos graus de aprendizagem dos usuários e suas diferentes interfaces e funcionalidades. Atualmente, encontra-se em fase de implementação a versão 3, com o aprimoramento de cada uma das etapas citadas anteriormente. Para validar, comprovar e testar a eficácia da metodologia desenvolvida para o RoboEduc, foram realizados experimentos, através de oficinas de robótica, com crianças dos quarto e quinto ano do ensino fundamental da Escola Municipal Ascendino de Almeida, localizada na periferia de Natal (Zona Oeste), Rio Grande do Norte. Como resultado preliminar da presente tecnologia, verificamos que o uso de robôs em conjunto com um software bem elaborado pode ser estendido a usuários leigos, sem a necessidade de conhecimentos prévios avançados de tecnologia. Assim, mostraram ser ferramentas acessíveis e eficientes no processo de inclusão digital.
9
  • JOSE ALBERTO DIAZ AMADO
  • Projeto e Implementação de um Sistema de Aquecimento no Laboratório de Avaliação de Medição em Petróleo.
  • Advisor : ANDRES ORTIZ SALAZAR
  • COMMITTEE MEMBERS :
  • ANDRE LAURINDO MAITELLI
  • ANDRES ORTIZ SALAZAR
  • CARLOS ALBERTO VILLACORTA CARDOSO
  • PABLO JAVIER ALSINA
  • Data: Sep 5, 2008


  • Show Abstract
  • O Laboratório de Avaliação de Medição em Petróleo (LAMP), da Universidade Federal Rio Grande do Norte (UFRN), tem como meta principal avaliar medidores de vazão BS&W, onde a simulação do maior numero de variáveis de operação em campo, garante uma avaliação com menor porcentagem de incertezas. O objetivo do trabalho foi projetar e controlar um sistema de aquecimento, o qual dará cobertura de controle na temperatura de forma segura e eficiente no laboratório. A temperatura é o parâmetro que mais influencia na exatidão em medição de vazão e BS&W, afetando diretamente a viscosidade e a densidade do fluido no teste. Para projetar o sistema de aquecimento foram de vital importância os requisitos do laboratório, os quais são condições e restrições atuais. Três alternativas para projetar o sistema foram avaliadas em função dos requisitos: trocador de calor, resistências externas e resistências internas. Depois de análises feitas para escolher a melhor alternativa para o sistema de aquecimento do laboratório, foram determinadas as estratégias de controle combinando metodos de control PID e logica fuzzy. Os melhores resultados obtidos de melhor performance usando logica fuzzy comparado com um clasico PID.
10
  • CLARISSA DE LUCENA NOBREGA
  • Otimização dos Parâmetros de Monopolos Planares de Microfita para Aplicações em Sistemas de Banda Ultra Larga
  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • LAERCIO MARTINS DE MENDONCA
  • PAULO HENRIQUE DA FONSECA SILVA
  • RONALDO DE ANDRADE MARTINS
  • Data: Oct 21, 2008


  • Show Abstract
  • Este trabalho apresenta uma investigação teórica e experimental sobre as propriedades de antenas de microfita para sistemas de banda ultralarga (ultra wideband, UWB). São consideradas configurações de monopolos elípticos com excentricidades diferentes, e monopolos circulares. Foram construídos dois protótipos para cada configuração de antena, um com a configuração típica de microfita e outro similar ao primeiro, mas com uma pequena abertura no plano de terra. Assim, este trabalho objetiva modificar a configuração do plano de terra dos monopolos projetados através da inserção de um recorte retangular, para fins de otimização e melhoria nos desempenhos das estruturas. Os resultados obtidos mostram que a introdução dessa abertura retangular no plano de terra permite melhorar a resposta em freqüência das antenas consideradas. Observa-se uma boa concordância entre os resultados medidos e simulados. Algumas propostas para a realização de trabalhos futuros são apresentadas.
11
  • MARCUS VINICIUS ARAUJO FERNANDES
  • Controlador Adaptativo por Modelo de Referência e Estrutura Variável Aplicado ao Controle de Ângulo de Carga e Fluxo de Campo de um Gerador Síncrono
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ALLAN DE MEDEIROS MARTINS
  • JOSE ALVARO DE PAIVA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Oct 23, 2008


  • Show Abstract
  • Nesta dissertação de mestrado é apresentada uma aplicação do Controlador Adaptativo por Modelo de Referência e Estrutura Variável em um Gerador Síncrono conectado a um barramento infinito, para o controle do ângulo de carga e fluxo de campo deste gerador. Uma teoria de desacoplamento é usada no modelo do Gerador Síncrono para se obter dois subsistemas, onde o ângulo de carga e o fluxo de campo podem ser controlados independentemente. A avaliação da estratégia de controle proposta será realizada através de simulações para o modelo desacoplado do Gerador Síncrono. Também será feita uma comparação com os controladores Proporcional Derivativo aplicado ao Gerador Síncrono desacoplado e Proporcional Integrativo Derivativo aplicado ao Gerador Síncrono acoplado, sendo este último, o sistema vigente hoje no Brasil. Os resultados das simulações comprovarão a eficiência e robustez desta estratégia de controle.
12
  • IVANOVITCH MEDEIROS DANTAS DA SILVA
  • Análise de Desempenho de Sistemas de Comunicação Sem-Fio para Monitoramento de Unidade de Produção de Poços Petrolíferos Terrestres
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • PAULO SERGIO DA MOTTA PIRES
  • RICARDO ALEXANDRE REINALDO DE MORAES
  • Data: Oct 30, 2008


  • Show Abstract
  • Grande parte do monitoramento de poços petrolíferos terrestres realizados atualmente está baseado em soluções sem fio (wireless). Todavia, essas soluções apresentam uma configuração defasada tecnologicamente na medida em que são utilizados rádios analógicos e topologias de comunicação ineficientes. Por outro lado, tecnologias que adotam rádios digitais podem proporcionar soluções mais eficientes relacionadas com o consumo de energia, segurança e tolerância a falhas. O trabalho investiga se as Redes de Sensores Sem Fio, tecnologia de comunicação que utiliza rádios digitais, são adequadas para o monitoramento de poços petrolíferos terrestres. Porcentagem de pacotes entregues com sucesso, consumo de energia, atrasos de comunicação e técnicas de roteamento para uma topologia em malha são as métricas usadas para validar a proposta através da ferramenta de simulação NS-2.
13
  • LIVIANE CATARINE ALMEIDA MELO
  • Contribuições para a Detecção e Identificação de Faltas em Inversores Multiníveis
  • Advisor : RICARDO LUCIO DE ARAUJO RIBEIRO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • EDISON ROBERTO CABRAL DA SILVA
  • RICARDO LUCIO DE ARAUJO RIBEIRO
  • Data: Nov 19, 2008


  • Show Abstract
  • Este trabalho apresenta contribuições para a detecção e identificação de faltas em inversores multiníveis, baseado no estudo do comportamento desse conversor sob essas condições de operação. Basicamente, a falta abordada consiste na abertura não comandada de uma das chaves de um inversor de tensão de três níveis com diodos de grampeamento. O funcionamento do conversor é caracterizado nos estados de pré e pós-falta. É, também, feita uma análise dos comportamentos das formas de onda das tensões de pólo, corrente de fase e correntes do barramento CC, as quais apontam características que possibilitam detectar falta e, ainda, em condições favoráveis, identificar o dispositivo que apresentou defeito. Uma estratégia de compensação da falta abordada (chave aberta) também é investigada, com o propósito de manter a continuidade de funcionamento do sistema de acionamento, quando da ocorrência de uma falha. A topologia proposta utiliza SCRs em paralelo com as chaves internas do inversor, a qual permite, em algumas ocasiões, a total utilização do barramento CC.
14
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • Controlador adaptativo backstepping a estrutura variável
  • Advisor : ALDAYR DANTAS DE ARAUJO
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • JOSENALDE BARBOSA DE OLIVEIRA
  • RAMON ROMANKEVICIUS COSTA
  • Data: Nov 20, 2008


  • Show Abstract
  • Neste trabalho, um controlador adaptativo backstepping a estrutura variável (Variable Structure Adaptive Backstepping Controller, VS-ABC) é apresentado para plantas monovariáveis, lineares e invariantes no tempo com grau relativo unitário. Ao invés das tradicionais leis integrais para estimação dos parâmetros da planta, leis chaveadas são utilizadas com o objetivo de aumentar a robustez em relação a incertezas paramétricas e distúrbios externos, bem como melhorar o desempenho transitório do sistema. Adicionalmente, o projeto do novo controlador é mais intuitivo quando comparado ao controlador backstepping original, uma vez que os relés introduzidos apresentam amplitudes diretamente relacionadas com os parâmetros nominais da planta. Esta nova abordagem, com uso de estrutura variável, também reduz a complexidade das implementações práticas, motivando a utilização de componentes industriais, tais como, FPGAs (Field Programmable Gate Arrays), MCUs (Microcontrollers) e DSPs (Digital Signal Processors). Simulações preliminares para um sistema instável de primeira e segunda ordem são apresentadas de modo a corroborar os estudos. Um dos exemplos de Rohrs é ainda abordado através de simulações, para os dois cenários adaptativos: o controlador backstepping adaptativo original e o VS-ABC.
15
  • ELDER ELDERVITCH CARNEIRO DE OLIVEIRA
  • Antenas de Microfita com Patch Quse-fractal para Aplicações em Redes WPAN/WLAN
  • Advisor : SANDRO GONCALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • ALFREDO GOMES NETO
  • PAULO HENRIQUE DA FONSECA SILVA
  • RONALDO DE ANDRADE MARTINS
  • SANDRO GONCALVES DA SILVA
  • Data: Dec 3, 2008


  • Show Abstract
  • As antenas de micro?ta estão em constante evidência nas pesquisas atuais, isso devido às inúmeras vantagens que apresentam. A geometria fractal aliada ao bom desempenho e comodidade das estruturas planares são uma excelente combinação para projetos e análise de estruturas cada vez menores e com características multi-ressonantes e banda larga. Essa geometria tem sido aplicada em antenas tipo patch em micro?ta para reduzir o seu tamanho e evidenciar o seu comportamento multi-banda. Em comparação com as antenas em micro?ta convencionais, as antenas patch quase-fractais apresentam freqüências de ressonância inferiores, possibilitando a fabricação de antenas ainda mais compactas. O objetivo desse trabalho consiste no projeto de antenas patches quase-fractal por meio da utilização de curvas fractais de Koch e Minkowski aplicado às margens radiante e não-radiante de uma antena inset-fed patch retangular convencional alimentada por linha de micro?ta com reentrâncias, inicialmente projetada para a freqüência de 2,45 GHz a ser observada. A técnica inset-fed é investigada para o casamento de impedâncias das antenas fractais, que são alimentadas através de linhas de micro?ta com reentrâncias. A e?ciência dessa técnica é investigada experimentalmente e comparada com simulações realizadas pelo software comercial Ansoft Designer, usado para a análise precisa do comportamento eletromagnético das antenas através do método dos momentos e pelo modelo neural proposto. Nessa dissertação um estudo bibliográ?co em teoria de antenas de micro?ta é realizado, o mesmo estudo é realizado a respeito da geometria fractal, dando ênfase a suas mais diversas formas, técnicas de geração desses fractais bem como sua aplicabilidade. Este trabalho ainda apresenta um estudo em redes neurais arti?ciais, evidenciando os tipos/arquitetura de redes utilizadas e suas características, bem como os algoritmos de treinamento que foram utilizados para sua implementação. As equações dos ajustes dos parâmetros para as redes utilizadas nesse trabalho foram deduzidas a partir do método do gradiente. Também será realizada uma investigação com ênfase na miniaturização dessas novas estruturas propostas, indicando o quanto uma antena projetada com contornos fractais é capaz de miniaturizar uma antena patch retangular convencional. O estudo também consiste de uma modelagem por meio de redes neurais arti?ciais dos mais diversos parâmetros eletromagnéticos das antenas quase-fractal. Os resultados apresentados demonstram a excelente capacidade das técnicas neurais para modelagem de antenas de micro?ta, e todos os algoritmos utilizados nesse trabalho na obtenção dos modelos propostos foram implementados no software comercial de simulação Matlab 7. Com a ?nalidade de validar os resultados obtidos, vários protótipos de antenas foram construídos, medidos em um analisador de rede vetorial e simulados em software para comparação.
16
  • MARCELO RIBEIRO DA SILVA
  • Novas Configurações de Monopolos Planares Quase-Fractais para Sistemas de Comunicações Móveis
  • Advisor : ADAILDO GOMES D ASSUNCAO
  • COMMITTEE MEMBERS :
  • ADAILDO GOMES D ASSUNCAO
  • GLAUCO FONTGALLAND
  • PAULO HENRIQUE DA FONSECA SILVA
  • RONALDO DE ANDRADE MARTINS
  • Data: Dec 29, 2008


  • Show Abstract
  • As propriedades únicas da geometria fractal têm-se mostrado bastante úteis para a construção de filtros, superfícies seletivas em freqüência, circuitos sintonizados e antenas, possibilitando soluções otimizadas para uma variedade de usos comerciais na faixa de microondas. A geometria fractal está incluída na tecnologia dos sistemas de comunicação por microondas devido a algumas propriedades interessantes para a fabricação de dispositivos compactos, com desempenho superior em termos de largura de banda, bem como, comportamento multibanda. Neste trabalho, descrevem-se os procedimentos para o projeto, construção e medição de monopolos quase-fractais de Koch, com níveis 1 e 2, projetados para se investigar o efeito produzido na largura de banda de antenas planares, a partir da utilização de estruturas quase-fractais nos seus patches retangulares. O efeito eletromagnético da variação do nível dos fractais, bem como, da miniaturização das estruturas, foram avaliados. Também foram realizadas parametrizações com o intuito de se verificar o comportamento da largura de banda, tanto para a perda de retorno quanto para o SWR. Os resultados foram obtidos através de medições realizadas por um analisador de redes vetorial e por meio de simulações no Ansoft HFSS. Algumas propostas para trabalhos futuros foram citadas.
Thesis
1
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • H-N2N: Uma Arquitetura Hierárquica Escalável Para Ambientes de Realidade Mista de Grande Porte
  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • JAUVANE CAVALCANTE DE OLIVEIRA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • NATASHA CORREIA QUEIROZ LINO
  • TATIANA AIRES TAVARES
  • Data: Feb 15, 2008


  • Show Abstract
  • Neste trabalho, propomos uma solução para resolver o problema de escalabilidade encontrado nos ambientes virtuais e de realidade mista colaborativos de grande porte, que usam o modelo cliente-servidor hierárquico. Basicamente, usamos uma hierarquia de servidores. Quando a capacidade de um servidor é atingida, um novo servidor é criado subordinado a ele e a carga atual do sistema é distribuída entre eles (pai e filho). Propomos ferramentas e técnicas eficientes para solucionar problemas inerentes ao modelo cliente-servidor, tais como a definição de agrupamentos de usuários, a distribuição e redistribuição de usuários entre servidores e operações de mixagem e filtragem, que são necessárias à redução de fluxo de informação entre servidores. O novo modelo e técnicas propostas foram testados, em simulação, emulações e em aplicações interativas que foram implementadas. Os resultados destas experimentações mostram melhorias nos modelos tradicionais anteriores, indicando a usabilidade do framework proposto em problemas de comunicação todos para todos. Este é o caso de jogos interativos e outras aplicações voltadas à Internet (incluindo ambientes multiusuário) e aplicações interativas do Sistema Brasileiro de Televisão Digital, a serem desenvolvidas pelo grupo de pesquisa.
2
  • HELIANA BEZERRA SOARES
  • ANÁLISE E CLASSIFICAÇÃO DE IMAGENS DE LESÕES DA PELE POR ATRIBUTOS DE COR, FORMA E TEXTURA UTILIZANDO MÁQUINA DE VETOR DE SUPORTE
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • ALLAN DE MEDEIROS MARTINS
  • ANA MARIA GUIMARAES GUERREIRO
  • JORGE DANTAS DE MELO
  • MARCO ANTONIO GARCIA DE CARVALHO
  • VICENTE IDALBERTO BECERRA SABLON
  • Data: Feb 22, 2008


  • Show Abstract
  • O câncer de pele é o mais comum de todos os cânceres e o aumento da sua incidência deve-se, em parte, ao comportamento das pessoas em relação à exposição ao sol. No Brasil, o câncer de pele não melanoma é o mais incidente na maioria das regiões. A dermatoscopia e videodermatoscopia são os principais tipos de exames para o diagnóstico de doenças da pele dermatológicas. O campo que envolve o uso de ferramentas computacionais para o auxílio ou acompanhamento do diagnóstico médico em lesões dermatológicas ainda é visto como muito recente. Vários métodos foram propostos para classificação automática de patologias da pele utilizando imagens. O presente trabalho tem como objetivo apresentar uma nova metodologia inteligente para análise e classificação de imagens de câncer de pele, baseada nas técnicas de processamento digital de imagens para extração de características de cor, forma e textura, utilizando a Transformada Wavelet Packet (TWP) e técnicas de aprendizado de máquina denominada Máquina de Vetor de Suporte (SVM – Support Vector Machine). A Transformada Wavelet Packet é aplicada para extração de características de textura nas imagens. Esta consiste de um conjunto de funções base que representa a imagem em diferentes bandas de freqüência, cada uma com resoluções distintas correspondente a cada escala. Além disso, são calculadas também as características de cor da lesão que são dependentes de um contexto visual, influenciada pelas cores existentes em sua volta, e os atributos de forma através dos descritores de Fourier. Para a tarefa de classificação é utilizado a Máquina de Vetor de Suporte, que baseia-se nos princípios da minimização do risco estrutural, proveniente da teoria do aprendizado estatístico. A SVM tem como objetivo construir hiperplanos ótimos que apresentem a maior margem de separação entre classes. O hiperplano gerado é determinado por um subconjunto dos pontos das classes, chamado vetores de suporte. Para o banco de dados utilizado neste trabalho, os resultados apresentados mostraram-se eficiente obtendo um acerto global de 92,73% para melanoma, e 86% para lesões não-melanoma e benigna. O potencial dos descritores extraídos aliados ao classificador SVM tornou o método capaz de reconhecer e classificar as lesões analisadas.
3
  • CAIO DORNELES CUNHA
  • Controlador em Modo Dual Adaptativo Robusto-DMARC
  • COMMITTEE MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • DAVID SIMONETTI BARBALHO
  • FRANCISCO DAS CHAGAS MOTA
  • LIU HSU
  • MARCELO CARVALHO MINHOTO TEIXEIRA
  • Data: Feb 24, 2008


  • Show Abstract
  • Neste trabalho é apresentada uma proposta de um controlador, denominado Controlador em Modo Dual Adaptativo Robusto (DMARC), que estabelece uma ligação entre um controlador adaptativo por modelo de referência (MRAC) e um controlador adaptativo por modelo de referência e estrutura variável (VS-MRAC). A idéia básica é incorporar as vantagens de desempenho transitório do controlador VS-MRAC com as propriedades de regime permanente do controlador MRAC convencional. São desenvolvidos dois algoritmos básicos para o controlador DMARC. No primeiro o ajuste do controlador é feito, em tempo real, através da variação de um parâmetro na lei de adaptação. No segundo algoritmo a lei de controle é gerada, utilizando o modelo Takagi-Sugeno da lógica nebulosa, para obter uma composição ponderada das leis de controle do MRAC e do VS-MRAC. Em ambos os casos, o esquema combinado de controle é mostrado ser robusto às incertezas paramétricas e perturbações externas, além de apresentar um desempenho rápido e pouco oscilatório durante o transitório e um sinal de controle suave em regime permanente.
4
  • ANTONIO DE PADUA DE MIRANDA HENRIQUES
  • Classificação de Imagens de Ambientes Coralinos: Uma Abordagem Empregando uma Combinação de Classificadores e Máquina de Vetor de Suporte
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • DOUGLAS FRANCISCO MARCOLINO GHERARDI
  • FRANCISCO HILARIO REGO BEZERRA
  • LUIZ MARCOS GARCIA GONCALVES
  • MARCELINO PEREIRA DOS SANTOS SILVA
  • RICARDO FARIAS DO AMARAL
  • Data: Aug 8, 2008


  • Show Abstract
  • A utilização de mapas, derivados da classificação de imagens de sensores remotos orbitais, tornou-se de fundamental importância para viabilizar ações de conservação e monitoramento de recifes de corais. Entretanto, a acurácia atingida no mapeamento dessas áreas é limitada pelo efeito da variação da coluna d’água, que degrada o sinal recebido pelo sensor orbital e introduz erros no resultado final do processo de classificação. A limitada capacidade dos métodos tradicionais, baseados em técnicas estatísticas convencionais, para resolver este tipo de problema determinou a investigação de uma estratégia ligada à área da Inteligência Computacional. Neste trabalho foi construído um conjunto de classificadores baseados em Máquinas de Vetor de Suporte e classificador de Distância Mínima, com o objetivo de classificar imagens de sensoriamento remoto de ecossistema de recifes de corais. O sistema é composto por três estágios, através dos quais acontece o refinamento progressivo do processo de classificação. Os padrões que receberam uma classificação ambígua em uma determinada etapa do processo são reavaliados na etapa posterior. A predição não ambígua para todos os dados aconteceu através da redução ou eliminação dos falsos positivos. As imagens foram classificadas em cinco tipos de fundos: águas profundas, corais submersos, corais intermarés, algas e fundo arenoso. A melhor acurácia geral (89%) foi obtida quando foram utilizadas Máquinas de Vetor de Suporte com kernel polinomial. A acurácia das imagens classificadas foi comparada, através da utilização de matriz de erro, aos resultados alcançados pela aplicação de outros métodos de classificação baseados em um único classificador (redes neurais e o algoritmo k-means). Ao final, a comparação dos resultados alcançados demonstrou o potencial do conjunto de classificadores como instrumento de classificação de imagens de áreas submersas, sujeitas aos ruídos provocados pelos efeitos atmosféricos e da coluna d’água.
5
  • MARCIA MARIA DE CASTRO CRUZ
  • Uma Fundamentação Intervalar Aplicada à Morfologia Matemática
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • AARAO LYRA
  • ADRIAO DUARTE DORIA NETO
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • GRAÇALIZ PEREIRA DIMURO
  • REGIVAN HUGO NUNES SANTIAGO
  • RONEI MARCOS DE MORAES
  • Data: Sep 5, 2008


  • Show Abstract
  • Este trabalho apresenta uma abordagem intervalar para lidar com imagens que contêm incertezas, bem como tratar essas incertezas através de operações morfológicas. Foram apresentados dois modelos intervalares. Para o primeiro, é introduzido um espaço algébrico com três valores que foi construído com base na lógica tri-valorada de Lukasiewiecz. Com essa estrutura algébrica, introduz-se a teoria das imagens binárias intervalares, que estende o modelo clássico binário, com a inclusão da informação de incerteza. A mesma pode ser aplicada para representar imagens binárias com incerteza em certos pixels, que foi originada, por exemplo, durante o processo da aquisição da imagem. A estrutura reticular dessas imagens permite a definição de operadores morfológicos, onde as incertezas são tratadas localmente. O segundo modelo, estende o modelo clássico para imagens em níveis de cinza, onde as funções que representam essas imagens são mapeadas em um conjunto finito de valores intervalares. A estrutura algébrica desse conjunto pertence a classe dos reticulados completos, o que permite a definição dos operadores elementares da morfologia matemática, dilatação e erosão para essas imagens. Dessa forma, fica estabelecida uma teoria intervalar aplicada à morfologia matemática para tratar problemas de incertezas em imagens.
6
  • CRISLUCI KARINA SOUZA SANTOS CANDIDO
  • CLASSIFICAÇÃO DE DISTÚRBIOS NA REDE ELÉTRICA USANDO REDES NEURAIS E WAVELETS
  • Advisor : MANOEL FIRMINO DE MEDEIROS JUNIOR
  • COMMITTEE MEMBERS :
  • BENEMAR ALENCAR DE SOUZA
  • JORGE DANTAS DE MELO
  • JOSE JULIO DE ALMEIDA LINS LEITAO
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • UBIRATAN HOLANDA BEZERRA
  • Data: Oct 13, 2008


  • Show Abstract
  • Análises pós-despacho de sinais oriundos de registradores de perturbações fornecem muitas vezes informações importantes para identificação e classificação de distúrbios nos sistemas, visando a uma gestão mais eficiente do fornecimento de energia elétrica. Para auxiliar nessa tarefa, faz-se necessário recorrer a técnicas de processamento de sinais, a fim de automatizar o diagnóstico sobre os tipos de distúrbio presentes nos sinais registrados. A transformada wavelet constitui-se em uma ferramenta matemática bastante eficaz na análise de sinais de tensão ou corrente, obtidos imediatamente após a ocorrência de distúrbios na rede. Este trabalho apresenta uma metodologia baseada na transformada wavelet discreta e na comparação de curvas de distribuição da energia de sinais, com e sem distúrbio, para diferentes níveis de resolução de sua decomposição, com o objetivo de obter descritores que permitam a sua classificação através do uso de redes neurais artificiais.
7
  • ANDERSON LUIZ DE OLIVEIRA CAVALCANTI
  • Análise e Desenvolvimento de Controladores Preditivos Multivariáveis Baseados em Multi- Modelos Bilineares
  • Advisor : ANDRE LAURINDO MAITELLI
  • COMMITTEE MEMBERS :
  • ADHEMAR DE BARROS FONTES
  • ANDRE LAURINDO MAITELLI
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • OTACILIO DA MOTA ALMEIDA
  • VALTER JUNIOR DE SOUZA LEITE
  • Data: Oct 17, 2008


  • Show Abstract
  • Este trabalho aborda aspectos relacionados à análise e ao desenvolvimento de controladores preditivos multivariáveis baseados em multi-modelos bilineares. O Controlador Preditivo Generalizado (GPC) Monovariável e Multivariável para o caso linear é apresentado, sendo destacadas suas propriedades, características principais e aplicações na indústria. O GPC bilinear, que é o controlador base de todo o desenvolvimento desta Tese, é apresentado através da abordagem da quasilinearização por degrau de tempo. Alguns resultados empregando este controlador são apresentados de forma a evidenciar o melhor desempenho do mesmo, quando comparado ao GPC linear, visto que os modelos bilineares representam melhor a dinâmica de determinados processos. A quasilinearização por degrau de tempo, devido ao fato de ser uma aproximação, provoca um erro de predição, que limita o desempenho deste controlador à medida que seu horizonte de predição aumenta. Devido ao referido erro de predição, o GPC bilinear com compensação iterativa é mostrado de forma a minimizar o referido erro, buscando um melhor desempenho que o GPC bilinear clássico. Alguns resultados utilizando o algoritmo de compensação iterativa são mostrados. O emprego dos multi-modelos é abordado nesta Tese, buscando suprir a deficiência existente em controladores baseados em modelo único, quando os mesmos são aplicados em processos com grandes faixas de operação. Formas de mensuração de distância entre modelos, também chamadas de métricas, consistem na principal contribuição desta Tese. Diversos resultados de aplicação em colunas de destilação simuladas, que se aproximam bastante do comportamento real das mesmas, foram realizados, e os resultados se mostraram satisfatórios.
8
  • RICARDO ALEXSANDRO DE MEDEIROS VALENTIM
  • Protocolo Multiciclos para Automação Hospitalar sobre Multicast com IEEE 802.3 utilizando IGMP Snooping
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ANA MARIA GUIMARAES GUERREIRO
  • GLAUCIO BEZERRA BRANDAO
  • JOSE DE RIBAMAR SILVA OLIVEIRA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • MEUSE NOGUEIRA DE OLIVEIRA JUNIOR
  • Data: Oct 31, 2008


  • Show Abstract
  • Os conceitos da automação industrial já estão a algum tempo sendo incorporados na área médica, passando também a ser utilizados na automação hospitalar. Nesse sentido, várias pesquisas têm sido desenvolvidas e geralmente tem abordado vários dos problemas que são pertinentes aos processos que podem ser automatizados no ambiente hospitalar. Considerando que nos processos de automação um fator imperativo é a comunicação, visto que os sistemas geralmente são distribuídos, a rede para transferência de dados passa a ser um elemento fundamental desses processos, pois devem ser capazes de prover a troca de dados e garantir as exigências impostas pelo processo de automação. É nesse contexto, que a presente tese de doutorado propôs, especificou, validou e analisou o PM-AH (Protocolo Multiciclos para Automação Hospitalar). O PM-AH é customizado para atender as exigências dos processos de monitoramento de pacientes (redes de controle) em ambientes hospitalares e visa garantir o determinismo nas comunicações otimizando o fator de utilização do meio de transmissão.
9
  • ADRIANO DE ANDRADE BRESOLIN
  • Reconhecimento de Voz através de unidades menores do que a palavra, utilizando Wavelet Packet e SVM, em uma nova Estrutura Hierárquica de Decisão
  • Advisor : ADRIAO DUARTE DORIA NETO
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • JORGE DANTAS DE MELO
  • JOSE MANOEL DE SEIXAS
  • JOSEANA MACEDO FECHINE
  • PABLO JAVIER ALSINA
  • Data: Dec 2, 2008


  • Show Abstract
  • O reconhecimento automático da voz por máquinas inteligentes tem sido a meta de muitos pesquisadores nas últimas cinco décadas. Neste período, inúmeros avanços foram alcançados, como por exemplo no campo de reconhecimento de palavras isoladas (comandos), o qual atualmente apresenta taxas de reconhecimento muito altas. No entanto, ainda se está longe de desenvolver um sistema que possa ter um desempenho parecido com o ser humano, ou seja, reconhecimento automático de voz em modo contínuo. Um dos grandes desafios das pesquisas de reconhecimento de voz contínuo é a grande quantidade de padrões existentes, pois as linguagens modernas tais como: Inglês, Francês, Espanhol e Português possuem aproximadamente 500.000 palavras ou padrões a serem identificados. A proposta deste trabalho é utilizar unidades menores do que a palavra tais como: fonemas, difones e sílabas como unidades base para o reconhecimento da voz, visando o reconhecimento quaisquer palavras sem necessariamente utilizá-las. O objetivo principal deste trabalho é reduzir a restrição imposta pela quantidade excessiva de padrões existentes, ou seja, a quantidade excessiva de palavras. Com o objetivo de validar esta proposta, o sistema foi desenvolvido e testado para o reconhecimento de palavras isoladas no modo dependente do locutor. O sistema apresentado neste trabalho foi desenvolvido com uma lógica de reconhecimento hierárquica baseada nas características de produção dos fonemas da língua Portuguesa do Brasil. Estas decisões são feitas através da utilização de redes neurais do tipo Máquinas de Vetor de Suporte agrupadas na forma de Máquinas de Cômite. Os principais descritores do sinal de voz utilizados, foram obtidos através da Transformada Wavelet Packet. Os descritores MFCC (Mel-Frequency Cepstral Coefficient) também são utilizados neste trabalho. Pode-se concluir que o método proposto apresentou bons resultados nas etapas de reconhecimento de vogais, consoantes (sílabas) e palavras se comparado com outros métodos existentes na literatura.
10
  • DIEGO RODRIGO CABRAL SILVA
  • Sistema de Detecção e Isolamento de Falhas em Sistemas Dinâmicos Baseado em Identificação Paramétrica
  • Advisor : LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • ANDRE LAURINDO MAITELLI
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • OSCAR GABRIEL FILHO
  • ROBERTO CÉLIO LIMÃO DE OLIVEIRA
  • Data: Dec 11, 2008


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  • O presente trabalho visa contribuir com a área de detecção e diagnóstico de falhas em sistemas dinâmicos através da proposta de uma nova arquitetura de sistemas de detecção e isolamento de falhas (FDI, Fault Detection and Isolation). A arquitetura proposta traz inovações no que se refere à maneira como as grandezas físicas do processo monitorado são relacionadas ao sistema FDI e, em conseqüência disso, à maneira como as falhas são detectadas, isoladas e classificadas. Uma busca por ferramentas matemáticas capazes de satisfazer os objetivos da arquitetura proposta apontou para o uso do filtro de Kalman e seus derivados EKF (Extended Kalman Filter) e UKF (Unscented Kalman Filter). O uso do primeiro algoritmo mostra-se eficaz no caso em que o processo monitorado apresenta uma relação linear entre suas grandezas físicas a serem monitoradas e sua saída. Os outros dois, caso a dinâmica seja não linear. Posteriormente, um comparativo entre o EKF e o UKF mostra que o segundo se adequa melhor às necessidades da arquitetura proposta. Os resultados mostrados no final da tese são referentes a plantas lineares e não-lineares, onde se pode observar a eficácia da arquitetura proposta quando a mesma foi aplicada a processos simulados e reais.
11
  • IGOR PINHEIRO DE SALES CABRAL
  • Novas Ferramentas para Monitoramento Ambiental Usando SIG Web
  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • AQUILES MEDEIROS FILGUEIRA BURLAMAQUI
  • LUIZ MARCOS GARCIA GONCALVES
  • RICARDO FARIAS DO AMARAL
  • VALERIA GONCALVES SOARES
  • Data: Dec 19, 2008


  • Show Abstract
  • O uso de Sistemas de Informações Geográficas (SIG) tem se tornado essencial nos campos onde os detalhes e estudos precisos da superfície terrestre são requeridos. Aplicações em monitoramento ambiental são exemplos que requerem o uso de um SIG para que os gestores e toda a comunidade envolvida possam realizar as análises e decisões em cima das áreas de proteção ambiental. Neste campo específico, um desafio é construir um SIG que possa ser alimentado dinamicamente com dados, permitindo que os próprios pesquisadores enviem freqüentemente os dados ao sistema. Em alguns casos, os dados são adquiridos de diferentes fontes e precisam ser centralizados em um só sistema. Para solucionar este problema, ferramentas foram implementadas nesta Tese, possibilitando que os dados espaciais sejam devidamente tratados na Web. Com efeito, a pesquisa envolvida nesta Tese tem início a partir da inserção e processamento de dados obtidos in-loco, como variáveis bióticas e geológicas, e é finalizada com a representação dessas informações na Web. Para a consecução deste processo dinâmico foram desenvolvidas ferramentas que tornam o MapServer mais flexível e dinâmico, permitindo que o próprio usuário envie os dados coletados. Além disso, um módulo que utiliza técnicas de interpolação espacial para auxiliar as análises espaciais foi, também, implementado. Como meio de validação do sistema foram utilizados dados provenientes de pesquisas em uma região de recifes de corais, no Nordeste do Brasil. Por fim, este sistema foi implementado através do uso dos conceitos de interatividade que são dados pelo AJAX, se tornando uma ferramenta para controle dos eventos relacionados ao monitoramento ambiental.
2007
Dissertations
1
  • FRANCISCO DE ASSIS F MATIAS
  • Comparação entre Modelos de Aerogeradores Síncronos Utilizando o Programa ATP
  • Advisor : JOSE TAVARES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • JOSE TAVARES DE OLIVEIRA
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • RICARDO FERREIRA PINHEIRO
  • UBIRATAN HOLANDA BEZERRA
  • Data: Dec 21, 2007


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  • A geração de eletricidade através da energia eólica teve, recentemente, um importante crescimento em todo planeta, com a existência de vários planos de instalações de potência eólica para o futuro. Dessa forma, o aumento na geração de eletricidade através da energia eólica requer, cada vez mais, análise de estudos da interação entre os parques eólicos e os sistemas elétricos de potência. Este trabalho tem como objetivos implementar modelos equivalentes de aerogeradores síncronos para representar um parque eólico no programa ATP e examinar o comportamento dos modelos através de simulações. Simulações com aplicações de faltas foram realizadas para avaliar o comportamento das tensões do sistema para cada modelo equivalente, através de comparações entre os resultados dos modelos propostos, para verificar se as diferenças obtidas permitem a adoção do modelo mais simples.
Thesis
1
  • KARLA DARLENE NEPOMUCENO RAMOS
  • CADZ: UMA METODOLOGIA DE PROJETO BASEADA EM Z PARA REDES-EM-CHIP

  • Advisor : IVAN SARAIVA SILVA
  • COMMITTEE MEMBERS :
  • BENJAMIN RENE CALLEJAS BEDREGAL
  • CLAUDIA MARIA FERNANDES ARAÚJO RIBEIRO
  • IVAN SARAIVA SILVA
  • JOSÉ ANTONIO GOMES DE LIMA
  • LUIZ AFFONSO HENDERSON GUEDES DE OLIVEIRA
  • Data: May 31, 2007


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  • The fast market growth of embedded systems and the growing capacity of circuits integration have created many challenges for the integrated hardware and software system design, offering countless research opportunities. The performance of a complex embedded system, which is characterized by the high structural complexity and functional diversity, it is related directly to the communication infrastructure. In the last years the Network-on-Chip emerged as interconnection structure to interconnect the components of complex embedded systems. Despite presenting some characteristics of the computer network, network-on-chip project is not a trivial task, because it deals with peculiar restrictions of the embedded systems that elevate the level of complexity of the same. It is ideal making use of methodologies and CAD tools that help the hardware designer on network-on-chip design to assist the requirements of its projects. This thesis proposes the methodology (Computer Aided Design based on Z), which uses formal methods as support to the qualitative analysis of properties of the communication system, even before the development of the own system. The methodology should be used in the initial phase of the project, being possible to be incorporated to a flow of traditional project, where the qualitative analysis can be followed by the code generation and quantitative analysis. The methodology is validated by studies cases that prove its effectiveness.

2005
Dissertations
1
  • MEIKA IWATA MONTEIRO
  • Predição de Promotores de Bacillus subtilis usando técnicas de Aprendizado de Máquina

  • COMMITTEE MEMBERS :
  • ADRIAO DUARTE DORIA NETO
  • JAUVANE CAVALCANTE DE OLIVEIRA
  • LUIZ MARCOS GARCIA GONCALVES
  • MARCILIO CARLOS PEREIRA DE SOUTO
  • Data: Dec 13, 2005


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  • Um dos grandes desafios da Bioinformática é manipular e analisar os dados acumulados nas bases de dados mundiais. A expressão dos genes em procariotos é iniciada quando a enzima RNA polimerase une-se com uma região próxima ao gene, chamada de promotor, onde é localizado os principais elementos regulatórios do processo de transcrição. Apesar do crescente avanço das técnicas experimentais (in vitro) em biologia molecular, caracterizar e identificar um número significante de promotores ainda é uma tarefa difícil. Os métodos computacionais existentes enfrentam a falta de um número adequado de promotores conhecidos para identificar padrões conservados entre as espécies. Logo, um método para predizê-los em qualquer organismo procariótico ainda é um desafio. Neste trabalho, apresentamos uma comparação empírica de técnicas individuais de aprendizado de máquina, tais como: Classificador Bayesiano Ingênuo, Árvores de Decisão, Máquinas de Vetores de Suporte, Redes Neurais do tipo VotedPerceptron, PART e k-Vizinhos Mais Próximos e sistemas multiclassificadores (Bagging e Adaboosting) e Modelo Oculto de Markov à tarefa de predição de promotores procariotos em Bacilos subtilis. Utilizamos a validação cruzada para avaliar todos os métodos de AM. Para esses testes, foram construídas base de dados com seqüências de promotores e não-promotores do Bacillus subtilis e uma base de dados híbrida. Os métodos de AM obtiveram bons resultados com o SVM e o Naïve Bayes. Não conseguimos entretanto, obter resultados relevantes para a base de dados híbrida.

2004
Dissertations
1
  • BERNARDO EMÍDIO FERNANDES DE OLIVEIRA
  • *

  • Advisor : SERGIO VIANNA FIALHO
  • COMMITTEE MEMBERS :
  • MANOEL FIRMINO DE MEDEIROS JUNIOR
  • SERGIO VIANNA FIALHO
  • EDUARDO BRAULIO WANDERLEY NETTO
  • Data: Jul 30, 2004


  • Show Abstract
  • *

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