Engenharia Elétrica

URI Permanente desta comunidade

http://repositorio.ufes.br/handle/10/17617
Programa de Pós-Graduação em Engenharia Elétrica

Centro: CT
Telefone: (27) 4009 2663
URL do programa: https://engenhariaeletrica.ufes.br/pt-br/pos-graduacao/PPGEE

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Navegando Engenharia Elétrica por Autor "Almeida, Ailson Rosetti de"

Agora exibindo 1 - 5 de 5
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    Comparação das técnicas de modulação multiportadoras aplicadas às comunicações via rede elétrica
    (Universidade Federal do Espírito Santo, 2004-07-09) Dezan, Tadeu Leite; Segatto, Marcelo Eduardo Vieira; Salles, Evandro Ottoni Teatini; Almeida, Ailson Rosetti de; Lima, Antônio César de Castro
    The use of the low voltage energy grid as high speed communication networks, known as Power Line Communication – PLC, opens up the possibility to establish low cost widespread local area networks services such as internet. In this master thesis dissertation, transmission issues on the power line are investigated and modeling aproaches are investigated. Multi-carrier modulation based on orthogonal transmultiplexer is used, because of its fast algoritms capabilities. Three diferent techniques are compared: Orthogonal Frequency Division Multiplexing, Discrete Wavelet Multitone through Extended Lapped Transform and Wavelet Packet Modulation. The main characteristics of each technique, including their computational cost, are described based on the filter banks theory. The system performance is analysed in terms of the bit-error rate versus signal-tonoise rate in a multipath powerline channel.
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    Estudo do sinal eletroencefalográfico (EEG) aplicado a interfaces cérebro computador com uma abordagem de reconhecimento de padrões
    (Universidade Federal do Espírito Santo, 2005-09-06) Azevedo, Anderson Prado; Almeida, Ailson Rosetti de; Salles, Evandro Ottoni Teatini; Bastos Filho, Teodiano Freire; Andreão, Rodrigo Varejão
    The conjunction of signal processing, pattern recognition and brain electrical signal acquisition made possible a new communication modality, until now a subject for science fiction movies: the Brain-Computer Interface (BCI). This complex system can acquire and process the brain signals in order to obtain information to be used as a control signal. This innovation can benefit people who have neuromuscular disorders, which cause damages on the volunteer movement. These people would communicate, or even move, using a BCI to control electronic devices. Looking ahead, these systems can be used in other applications, mainly for multimedia purposes. The purpose of this work is study the EEG characteristics, the signal processing and pattern recognition techniques in order to use in a Brain Computer Interface (BCI) For this, will be used a international data base, in order to compare our results with results of other international groups. In this context, this work describes the human brain and the EEG characteristics relevant to BCI understanding. Moreover, it presents the implementation of a pattern recognition system, which is able to classify the motor imagination laterality with accuracy over 85%.
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    Implementação de métodos biométricos bi-modais baseados em fusão de características para reconhecimento de indivíduos
    (Universidade Federal do Espírito Santo, 2007-08-24) Salomão, João Marques; Salles, Evandro Ottoni Teatini; Almeida, Ailson Rosetti de; Baptista, Edson; Montalvão Filho, Jugurta Rosa; Sarcinelli Filho, Mário; Bastos Filho, Teodiano Freire
    This research proposes a bi-modal personal recognition system based on the information fusion in the level of the characteristics (also called features). The biometric and behavioral features considered in the validation of our proposal are obtained from the video sequences of the human gait and face images. It evaluates some proposals of architectures and algorithms in the implementation of multiple biometric methods for recognition and authentication of individuals through the fusion of face features and the human gait, whose research subject is scarcely available in the scientific literature. The choice of the approach for the fusion of the two particularly considered information sources (not to be confused with multiple attributes of a feature vector from one information source) is justified by the supposition that it must offer a better classification performance, robustness and safety as it allows the night identification at a certain distance. Furthermore, it is considered less intrusive than all the other biometric systems since it presents little or no need for the collaboration of a person to be identified. The research, being an state of the art theme, has few bibliographical references and starts by evaluating the performance of the human recognition system through gait as it applies, on the video sequences, techniques of extraction and selection of silhouette features based on PCA (Principal Component Analysis), ICA (Independent Component Analysis), Wavelet transforms and PoV (Proportion of Variances), combined with the classifiers based on Euclidian distances, SVM (Support Vector Machines) and neural networks with RBF (Radial Base Functions). Using databases of public domain, a special study was carried out on gait aiming at an initial evaluation of its performance in human recognition systems, as well as the choice of methods and techniques more appropriate to make the fusion of this gait with the face images of the individual. As an improvement, on a second step, own databases were obtained based on an experimental setup that allowed the extraction of silhouettes from gait video sequences as well as face images corresponding to each sequence. This research also evaluated the performance of the recognition system when determining the fusion of both biometric features. Then, after the definition of the most adequate architecture, the fusion of two biometric systems face-gait on public domain databases, as well as our particular one, is proposed and implemented. In this final phase of the work, the proposed implementations use extraction techniques and features selection based on gait silhouettes energy, in the proportion of variances (PoV) and in the classification algorithms based on neural networks with radial base functions (RBF). The obtained results allowed the evaluation of the non-error rates, the false acceptance (FAR) and rejection rates (FRR) and the system performance, when the vectors of individual features of the face images alone, the gait video sequences alone, as well as the fusion of both are considered, confirming the validity and viability of the application of our proposal of fusion in the feature level in the bimodal human recognition system
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    Modelo de Seleção de Carteiras Baseado em Erros de Predição
    (Universidade Federal do Espírito Santo, 2008-12-18) Freitas, Fábio Daros de; Souza, Alberto Ferreira de; Almeida, Ailson Rosetti de; Salles, Evandro Ottoni Teatini; Zandonade, Eliana; França, Felipe Maia Galvão
    This work presents a new prediction errors-based portfoliooptimization model that cap-tures short-term investment opportunities. We used autoregressive moving references neuralnetwork predictors to predict the stock’s returns and derived a risk measure based on thepredictor’s errors of prediction that maintains the same statistical foundation of the mean-variance model. The efficient diversification effects hold by selecting predictors with lowand complimentary error profiles. A large set of experimentswith real data from the Brazil-ian stock market was employed to evaluate our portfolio optimization model, which includedthe examination of the Normality of the errors of prediction. Our main results showed that itis possible to obtain Normal prediction errors with non-Normal series of stock returns, andthat the prediction errors-based portfolio optimization model better captured the short termopportunities, outperforming the mean-variance model andbeating the market index.
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    Sistema de visão para robôs móveis: uma aplicação ao reconhecimento de referências geométricas
    (Universidade Federal do Espírito Santo, 1999-02-26) Freitas, Roger Alex de Castro; Sarcinelli Filho, Mário; Bastos Filho, Teodiano Freire; Almeida, Ailson Rosetti de; Rillo, Márcio
    The availability of sensorial data is an important issue for the navigation systemof autonomous mobile robots. The robot needs information about its surroundingenvironment in order to make a decision on what to do when it faces an obstacle. Insome cases, it not only does need to detect the presence of the obstacle but also torecognize it. This way, it is necessary that the onboard sensing system be much morespecialized. For an agent-based controlled autonomous mobile robot, a sensing systemthat combines ultrasonic sensors and artificial vision is here addressed. It makesavailable information about the type of obstacle detected in the trajectory of the robot, aswell as the distance from the detected object to the robot. This external sensing systemis also able to avoid the generation of redundant and unnecessary information, besidesnot demanding too much computational effort to process the acquired images onboardthe robot