Programa de Pós-Graduação em Engenharia Elétrica - PPGEE/ITEC

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2314

O Programa de Pós-Graduação em Engenharia Elétrica (PPGEE) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA) foi o primeiro e é considerado o melhor programa de pós-graduação em Engenharia Elétrica da Região Amazônica. As atividades acadêmicas regulares dos cursos de mestrado e doutorado são desenvolvidas principalmente nas Faculdades de Engenharia Elétrica e Engenharia de Computação, supervisionadas pela Coordenação do Programa de Pós-Graduação em Engenharia Elétrica (CPPGEE).

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Acesso aberto (Open Access)
Desenvolvimento de uma ferramenta de autoria de conteúdo para aprendizado via web
(Universidade Federal do Pará, 2003-03-27) LOPES, Luiz Alano Alexandre; OLIVEIRA, Roberto Célio Limão de; http://lattes.cnpq.br/4497607460894318
Web has been very used lately for companies and institutions of education as a way to offer learning. The creation of contents for the learning through web is an activity that has demanded human resources specialized in technologies and concepts, so that the contents created are not restricted the tools, platforms and formats of presentation. This work presents the development of a content authoring tool prototype for learning through web, in which the created contents are independents of the authoring tool, platform and presentation formats that are used. Being a development work, a process is defined and its phases and activities are used to organize the job and to register all the taken decisions.
Acesso aberto (Open Access)
Estudo de secagem por microondas e eólica-solar térmica
(Universidade Federal do Pará, 2003-04-29) PAIVA, Reginaldo Sabóia de; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; PINHO, João Tavares; http://lattes.cnpq.br/0847897516772421
With the main objective of studying and developing methodologies of control and simulation of microwave drying processes, this work uses as tool the physical-mathematical modelling of the thermal effects and mass transfer caused by microwave radiation in porous solid materials, taking into account the important variables for each case. Several results are presented, such as simulations of electric field profiles, power density, temperature and humidity inside materials with homogeneous characteristics and with simple geometry for the one, two and three-dimensional excitations. As a complementary study, the thermal process for the sizing of solar and wind dryers is modeled including the presentation of the results of the simulations developed.
Acesso aberto (Open Access)
Utilização de ambientes virtuais tridimensionais colaborativos em visualização de informação
(Universidade Federal do Pará, 2005-01-14) SOUZA JÚNIOR, Rosevaldo Dias de; MEIGUINS, Bianchi Serique; http://lattes.cnpq.br/3032638002357978; RIBEIRO FILHO, Manoel; http://lattes.cnpq.br/9329438229733907
Now thanks to the exponential evolutionary process of the hardware equipments, mainly the related to storage of data, it is possible to store enormous amounts of data, of all possible types, in a centralized base and/or distributed. There are some a little years ago was known what to do with such amount of stored data, in the days you act is known already that the organization that best to dominate the coming information of the is half that more chance will have to be well happened. Based on the mentioned premises is necessary that the responsible for the take of decision use tools of information visualization to aid in the ruling process, doing with that the same if turns more reliable, fast, intuitive and accurate. The information visualization uses techniques of data presentation with the objective of turning them more perceptible and intuitive for the user, however when there is need to present great amounts of data, the visualization is prejudiced for several reasons. To resolve this visualization problem, the use of the Virtual Reality (VR) if it turns essential due to the possibility that this interface provides just as interaction and navigability, characteristics that turn the most productive and interesting visualization. However, usually the ruling of decision is not made by a single person, and the tools in his great majority are mono-users, harming the ruling decision, mainly if the people are distant some of the other ones. With a collaborative environment of data visualization, it is possible to discuss on the same vision of data decreasing the time and unnecessary misunderstandings to the ruling decision. This work has for aim project and implementation a tool of information visualization in an environment three-dimensional virtual collaborative to aid the user in the ruling decentralized decision. Therefore it was used in the development of this characteristic tool of the areas of Database, Information Visualization and Collaborative Virtual Environments.
Acesso aberto (Open Access)
Amplificador para registro de potenciais corticais
(Universidade Federal do Pará, 2005-02-02) CARDOSO, Marcelo Ramos; SILVA, Ivan Sebastião de Souza e; http://lattes.cnpq.br/2033251521156161
Many organs in the human body manifest their functions through electric activities. Measurements of these and other biopotentials can provide vital clues that permits study as real functions of the organs. These measurements are not an easy task because envolves extremely low amplitudes data acquisition, between 1 μV and 10 mV, and also because these bioelectric recordings are often disturbed by an excessive level of interference presents, resulting in signal/noise degradation. Therefore, the biopotential amplifier project must be associated with precaution to final circuit can meet great characteristics in such signals measureming. This work shows a study about biopotentials origins, their characteristics, circuits used in signal amplifiering and filtering, interferences present in measurement systems and some circuits used to reduce such interferences. Thereafter, is developed a cortical biopotential amplifier with filtering and gain blocks. The tests with amplifier where realized by registering a visual evoked potential and the electroencephalogram. In the experimental results is possible to observe a satisfactory equipment performance.
Acesso aberto (Open Access)
Análise da qualidade de energia em sistemas de distribuição através de medição e fluxo de carga harmônico trifásico
(Universidade Federal do Pará, 2005-02-10) BRANCHE, Marcos Nascimento; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
This work presents an analysis about the power quality, carried out in a real electrical energy distribution grid, considering different customers groups, located in the low voltage grid. The study was made in two steps. The first one through measurements registered in the transformers of the distribution grid supplied by CEA – Amapá’s Electricity Company, previously classified in groups as: commercial group, residential group and home-and-commercial group, identifying and characterizing the generators sources of harmonics generation in the system, making possible, this way, an analysis of the harmonic injection level in the distribution grid as well as the impacts these distribution sources of harmonic generation can provoke in the power quality offered by the CEA utility. The last stage of the study presents the use of a threephase harmonic load flow, where, considering the harmonic profile found out through the measurements carried out, a global evaluation of the system is provided.
Acesso aberto (Open Access)
Modelagem e avaliação de estabilidade transitória de aerogeradores síncronos com magneto permanente em sistemas de energia elétrica
(Universidade Federal do Pará, 2005-04-29) SANTOS, Fernando Manuel Carvalho da Silva; NUNES, Marcus Vinicius Alves; http://lattes.cnpq.br/9533143193581447; BRANCO, Tadeu da Mata Medeiros; http://lattes.cnpq.br/8911039344594817
This work presents a study of the dynamic behaviour of permanent magnet variable speed wind generators, comparing it with doubly-fed and squirrel cage assynchronous generators. It also presents transient studies that have to be considered when evaluating the impacts of the grid-connection of wind turbines in the presence of the three technologies mentioned above, inserted in a standard electrical power system and supposing the operation of the wind farm together with conventional generation sources that use a diesel prime mover. The studies developed in this work are simulated through an algorithm of transient stability analysis, developed on MATLABTM computational programming language.
Acesso aberto (Open Access)
Análise da área de vulnerabilidade e estabilidade de tensão em sistemas elétricos com a inserção de parques eólicos
(Universidade Federal do Pará, 2005-09-30) MATOS, Kayt Nazaré do Vale; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
The present dissertation evaluates the voltage sag and stability of the real electrical system with the insertion of wind farms. The voltage sags studies serve of base for determination of the vulnerability areas of the electrical system, in which, in turn, the aspects are investigated regarding the voltage instability caused by the integration of wind systems with asynchronous generators. For that, the computational program ANAQUALI developed by CEPEL (Centro de Pesquisas de Energia El?trica) was used. In the study of the voltage dynamic behavior due to short circuit, in which the wind system is inserted in the conceptions of fixed speed and variable speed, a computational program developed in the MATLABTM software is used. The results of these simulations evidence that variable speed wind system provides a larger voltage stability edge to the electrical system, due to presence of the speed and voltage control. These studies commonly are not applied to the distributed generation system, and therefore, this dissertation also contributes in this aspect, and the results can serve of base for the planning of wind parks inserted in conventional electrical systems.
Acesso aberto (Open Access)
Desenvolvimento e animação de atores sintético e articulados: uma simulação futebolística
(Universidade Federal do Pará, 2005-12-09) QUINTO, Wanderson Alexandre da Silva; RIBEIRO FILHO, Manoel; http://lattes.cnpq.br/9329438229733907
This master’s dissertation aims to construct one 3D virtual environment in the form of a soccer stadium where simulations of a soccer game will be carried through, with the use of independent avatars. The construction of avatar use the H - Anim 1.1 modeling technique that it brings the concept of hierarchies and articulated body. The implementation of the application was developed with Java and API Java 3D. The autonomy is obtained by aid of Artificial Intelligence (AI) that it will act in the solution of the problems together with the use of rules previously known and tested. Intelligence, in this in case that, it can be observed by the use of three main components of the architecture of avatar: physical characteristics, behaviors and knowledge. For a better efficiency in the choice of which action avatar must make, was developed a strategy with assists of genetic algorithms that provides a better exactness.
Acesso aberto (Open Access)
Modelo estatístico para aplicações no planejamento de sistemas móveis celulares em ambiente indoor multifontes
(Universidade Federal do Pará, 2005-12-15) LIMA, Rosely dos Anjos; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
The project of systems of mobile communications requires the knowledge of the environment where it will be implemented. For so much, the accuracy is looked for in the prediction of propagation of the signal through the use of prediction models. The present work proposes an empirical model for estimating of the signal strength received in indoor environments that presents more than indoor transmitter source, using Distributed Antennas Systems (DAS). The method presents a generalization for the case of multiple sources, also called multisources and as particular case to only one source. The modeling is made through the use of radial go away of each transmitter, with aim to consider the variability of the signal in indoor environments. These some disturbances in the signal, that they cause fast fading; they are characterized through the statistical distributions of fading. The most used as of Rayleigh, Rice and Nakagami are presented for characterization of the channel; besides the distributions recently developed are calculated, so Kappa-mi and Eta-mi. For the validation of the model, campaigns of measurements in shopping center were made, where possesses one DAS, with the test in two distinct environments, a supermarket and a feeding square. The simulations are carried out through using the software MATLAB® and the performance of the results evaluated through the calculation of the absolute error, standard deviation and rms error.
Acesso aberto (Open Access)
Controle automático de adição de AlF3 em cubas de redução de alumínio, usando lógica fuzzy
(Universidade Federal do Pará, 2005-12-21) PEREIRA, Vanilson Gomes; OLIVEIRA, Roberto Célio Limão de; http://lattes.cnpq.br/4497607460894318
This work describes a data analysis system, which generates an intelligent aluminum fluoride (AlF3) addition strategy for electrolytic cells. The project is based on Fuzzy logic concepts, wherein the knowledge accumulated by the process specialist is translated in a qualitative manner into a set of linguistic rules such as: IF THEN. The use of this fuzzy technique for fluoride addition control seeks to explicitly represent an implicit knowledge, retained by the cell operators of the electrolytic cells. Due the conventional system not to contemplate the variations of the phenomena that they involve the dynamics of the process, a controller fuzzy was implemented in the real system for taking of decisions, using the minimum model of Mandani. Based this model, the process variables to input fuzzy system, such as bath temperature and fluoride of aluminum were manipulated to estimate the tendency up and down, through the Method of Least Squares(MLS). The controller fuzzy is applied to calculate the amount of fluoride of aluminum (AlF3) to be added in the electrolytic cells in an automatic way without the need of the the specialist?s of the process intervention. The use of a fuzzy control system is justified by the fact of not having an available dynamic model for aluminum fluoride addition process in electrolytic cells. This lack of modeling is due to the great complexity of the phenomena involved in a cell, which are thermodynamic and electromagnetic processes linked together.
Acesso aberto (Open Access)
Classificação fonética utilizando Boosting e SVM
(Universidade Federal do Pará, 2006-02-17) TEIXEIRA JÚNIOR, Talisman Cláudio de Queiroz; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
With the aim of setting up a Automatic Speech Recognition (ASR) system, a task named Phonetic Classification can be used. That task consists in, from a speech sample, deciding which phoneme was pronounced by a speaker. To ease the classification task and to enhance the most marked characteristics of the phonemes, the speech samples are usually pre-processed by a front-end. A front-end, as a general rule, extracts a set of features to each speech sample. After that, these features are inserted in a classification algorithm, that (already properly trained) will try to decide which phoneme was pronounced. There is a rule of thumb which says that the more features the system uses, the smaller the classification error rate will be. The disadvantage to that is the larger computational cost. Feature Selection task aims to show which are the most relevant (or more used) features in a classification task. Therefore, it is possible to discover which are the redundant features, that make little (or no) contribution to the classification task. The aim of this work is to apply SVM classificator in Phonetic Classification task, using TIMIT database, and discover the most relevant features in this classification using Boosting approach to implement Feature Selection.
Acesso aberto (Open Access)
IETS: Ferramenta interativa de ensino de SQL
(Universidade Federal do Pará, 2006-03-24) FREIRE, José Antônio Sarmanho dos Santos; FAVERO, Eloi Luiz; http://lattes.cnpq.br/1497269209026542
This work considers a tool in the Web for programming teaching. The work is based on a study of case for teaching of the programming language of data bases SQL and is inserted in the context of an interactive environment of learning. This experimental tool for teaching of programming languages, presents as objective: 1) complete integration between the teaching of concepts of programming with example of fragments of executable programs on line; 2) integration with a component of evaluation of programs verifying it the reply of the learner is the same one of the teacher; 3) complete control of the learner´s activities (how many examples had been executed; in each exercise, how many execution attempts had been made, etc). 4) to serve as a laboratory for experimentation of tow new techniques of evaluation and accompaniment, that are being searched in works in parallel: (a) automatic evaluation of metric programs with of software engineering , allowing informing how much the solution of the student if approaches to a “ideal solution”; e (b) automatic evaluation of discursive conceptual questions, besides allowing the traditional objective questions. This work is a first step in the direction of construction of an environment total attended (for example with automatic evaluation) for teaching of the programming language SQL, where the teacher will have a minimum load of work, more as supervisor.
Acesso aberto (Open Access)
Avaliação estocástica de afundamentos de tensão através de análise de curtos-circuitos deslizantes e banco de dados relacional
(Universidade Federal do Pará, 2006-03-30) SILVA, Jucileno Silva e; GARCEZ, Jurandyr Nascimento; http://lattes.cnpq.br/7097554286671669; CARDOSO JÚNIOR, Ghendy; http://lattes.cnpq.br/6284386218725402
Nowadays, it is great the concern regarding the disturbances that affect electric power quality, especially voltage sags, due to the associated customer damages. This elapses from the growing presence of sensitive loads to theses disturbances, mainly in industrial processes. To evaluate the problem correctly, it is fundamental to have reliable estimates of the number and characteristics of the voltage sags that can affect certain load or process. In this context, this work proposes the implementation of a methodology for estimation of voltage sags that consists in calculate amplitude, duration and frequency of occurrence of the phenomenon, based on probabilistic study. In this study, the position of the fault along the lines is raffled, in order to best represent the randomness of occurrence of faults in the system. To evaluate the applicability of the implemented methodology, case studies are made using a real electric grid of a distribution utility in the north of Brazil (CELPA). The resultant analysis, allows to affirm that, the implemented methodology can be used efficiently to aid engineers in planning of electric systems and in diagnosing power quality related customer equipment problems.
Acesso aberto (Open Access)
Avaliação tecnológica, operacional e de gestão de sistemas híbridos para geração de eletricidade na Região Amazônica
(Universidade Federal do Pará, 2006-05-16) BARBOSA, Claudomiro Fábio de Oliveira; PINHO, João Tavares; http://lattes.cnpq.br/0847897516772421
The objective of this work consists of contributing with the knowledge on the hybrid power systems implanted in the Amazon Region and based on the use of the solar, wind and diesel-electric energy sources. The work presents firstly the state-of-the-art of the hybrid power systems, characterizing their historical evolution, the main types and classifications, the basic composition and the advantages and disadvantages of the electrification through these types of systems. Afterwards, the identification and the description of the regional systems is made through the existent bibliographical references and information collected in field researches. The technical, operational, economic and administrative characteristics of those systems are briefly analyzed, serving as basis to the proposition of models for hybrid power systems, which influence directly the operation strategy and administration of the regional hybrid power systems. Those models after being implemented will allow for the optimization of the operation of the systems and their sustainability.
Acesso aberto (Open Access)
Detecção, classificação e quantificação automática de variações de tensão de curta duração para aplicação em análise de pós-operação em sistemas de energia elétrica
(Universidade Federal do Pará, 2006-05-19) MACHADO, Raimundo Nonato das Mercês; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
The analysis of occurrences in electric power systems is of fundamental importance for secure operation of the system, and to maintain quality of the electric energy supplied to the consumers. The electric power utilities use equipments called disturbance registers (DR’s) for monitoring and diagnose of problems in the electric and protection systems. The waveforms usually analyzed in the electric power utilities operation centers, are those generated by events that usually cause the opening of lines due to circuitbreakers operation commanded by the protection devices. However, a great amount of stored data that can contain important information on the behavior and the performance of the system is not analyzed. The proposal of this work is to use the available data in electric power utilities control and operation centers obtained from DR’s equipments, to classify and quantify of automatic form signals that characterize power quality problems, such as, short duration voltage variations: sags, swells and interruptions. The proposed method uses wavelet transform to obtain a characteristic vector for voltages in phases A, B and C, and a probabilistic neural network is used for classification. The classified signals as presenting short-duration variation are quantified for duration and magnitude of the event, using the multiresolution decomposition signal analysis properties. Those parameters, then, will form a database where statistical procedures of analysis can be used to prepare reports regarding power quality features. The results obtained with the application of this proposed methodology to a real system are also presented.
Acesso aberto (Open Access)
Conversão grafema-fone para um sistema de reconhecimento de voz com suporte a grandes vocabulários para o português brasileiro
(Universidade Federal do Pará, 2006-06-12) HOSN, Chadia Nadim Aboul; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
Speech processing has become a data-driven technology. Hence, the success of research in this area is linked to the existence of public corpora and associated resources, as a phonetic dictionary. In contrast to other languages such as English, one cannot find, in public domain, a Large Vocabulary Continuos Speech Recognition (LVCSR) System for Brazilian Portuguese. This work discusses some efforts within the FalaBrasil initiative [1], developed by researchers, teachers and students of the Signal Processing Laboratory (LaPS) at UFPA, providing an overview of the research and softwares related to Automatic Speech Recognition (ASR) for Brazilian Portuguese. More specifically, the present work discusses the implementation of a large vocabulary ASR for Brazilian Portuguese using the HTK software, which is based on hidden Markov models (HMM). Besides, the work discusses the implementation of a grapheme-phoneme conversion module using machine learning techniques.
Acesso aberto (Open Access)
Caracterização de canais multipercurso utilizando filtros digitais parametrizados com técnicas de traçado de raios
(Universidade Federal do Pará, 2006-06-23) MELLO JÚNIOR, Harold Dias de; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362
In this work, multipath radio propagation channels are characterized by FIR filters. The filters parameters are obtained from ray-tracing techniques, jointly with electromagnetic theory needed to is application. As study of case, modeling of an outdoor wideband channel impulse response is undertaken and time dispersion issues are discussed.
Acesso aberto (Open Access)
Localização de falhas em linhas de transmissão utilizando decomposição harmônica e redes neurais artificiais
(Universidade Federal do Pará, 2006-07-05) GOMES, Cristiane Ruiz; VIEIRA JÚNIOR, Petrônio; http://lattes.cnpq.br/1958791286192330
This work proposes a new methodology for fails location in transmission lines. This methodology consists in using harmonic decomposition of the leakage current and in the application of an Artificial Neural Network (ANN), this is able to recognize patterns of normal and fails conditions of a transmission line. It was developed a Pi model capable to use real data of voltage and current of the three phases. In this model values of capacitance, inductance and resistance can be modified in agreement of weather conditions. Fails were generated in all the towers with different values of capacitance. The input/output data were used to train the neural network. The real voltage and current data acquisition were done by instruments installed in the two terminals of the Guamá-Utinga transmission line belonging to Centrais Elétricas do Norte - ELETRONORTE. The computation of the parameters was made by the well known matricial method and was improved by Finite Element Method. An ANN was developed with Matlab software. For training the ANN it was used the backpropagation resilient algorithm, which presented good performance, been fast and accurate. The ANN was trained by two different sets to analyze differences between outputs. In the two cases results were satisfactory.
Acesso aberto (Open Access)
Tolerância a falha em redes ópticas de nova geração
(Universidade Federal do Pará, 2006-08-21) SOUZA, Jaime Viana de; ABELÉM, Antônio Jorge Gomes; http://lattes.cnpq.br/5376253015721742
Availability is of considerable concern for network desingners due to the increasing importance of the information that pass through them, motivating the providers of telecommunications services to improve the capacity and the qyality of their backbones. Optical networks that use WDM (“Wavelength Division Multiplexing”) usually present control plane based in GMPLS (Generalized Multiproptocol Label Switching) architecture, because it provides one batter adequation between IP protocol and the optical layer. This work makes a comparative study, between the machanisms used for the traditional optical networks and the said ones of the next generation. It considers the adoption of different mechanism of fault tolerance in function of the traffic model, through simulations, in the networks implemented by SDH/SONET architecture and simulations in computer of the main mechanisms offered for the multilayer model IP-GMPLS/WDM to provide protection and restoration of connectivity in nexte-generation optical networks, being objectified to authenticate our proposal.
Acesso aberto (Open Access)
Desenvolvimento de aplicativos usando reconhecimento e síntese de voz
(Universidade Federal do Pará, 2006-08-30) SAMPAIO NETO, Nelson Cruz; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
Speech is a natural mechanism for human-machine interaction. Speech (or voice) technology is a well-developed field when one considers the international community. There is a wide variety of academic and industrial software. The majority of them assumes a recognizer or synthesizer is available, and can be programmed through an API. In contrast, there are no such resources in public domain for Brazilian Portuguese. This work discusses some of these issues and compares SAPI and JSAPI, which are APIs promoted by Microsoft and Sun, respectively. We also present two examples: a CALL application using SAPI-based speech synthesis in English and Portuguese, recognition in English, and visual agents; and a JSAPI-based software that incorporates speech synthesis and recognition to IRC through Java APIs.