5 research outputs found

    Aplicação de meta-heurísticas para afinação de analisadores de espectro de vibração baseados em sistemas microeletromecânicos

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    Orientadores: Mateus Giesbrecht, Fabiano FruettDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: O espectro de vibração mecânica é uma característica do domínio da frequência utilizada para o monitoramento de sistemas diversos e é, tradicionalmente, calculado pela Transformada Rápida de Fourier (FFT) -- do termo em inglês Fast Fourier Transform -- de uma série temporal. Uma alternativa viável, com diversas vantagens operacionais, é o uso de microacelerômetros gêmeos para a obtenção do espectro diretamente no domínio da frequência. Essa estratégia possui sua maior limitação nas diferenças encontradas nos parâmetros físicos de acelerômetros -- devidas a seu processo de fabricação --, de tal forma que o nível de distorção do espectro pode ser consideravelmente superior àquele encontrado no espectro levantado pela FFT. Para contornar essas diferenças, neste trabalho a afinação do microdispositivo analisador de espectro é proposta através do ajuste das amplitudes das tensões de atuação dos acelerômetros. Para realizar a afinação, a Evolução Diferencial (DE, do termo em inglês Differential Evolution) é usada e o problema da afinação é abordado sob duas diferentes perspectivas de otimização: uma mono-objetivo e uma multi-objetivo. Para ambos os problemas de otimização, as funções objetivo e restrições são baseadas nas componentes da série de Fourier do ganho de malha fechada do sistema analisador de espectro -- composição essa que depende das tensões de excitação. Para a solução do problema de otimização multi-objetivo, o algoritmo DE é devidamente adaptado. As vantagens e desvantagens de ambas as estratégias de afinação são discutidas em detalhe, bem como os resultados obtidos para a aproximação do conjunto de Pareto. Esses resultados -- especialmente o compromisso distorção-sensibilidade -- são demonstrados e discutidos. A validade da estratégia de afinação proposta é evidenciada, uma vez que é capaz de determinar as amplitudes das tensões a serem aplicadas ao micro analisador de espectro para atender os requisitos de nível de distorção e sensibilidadeAbstract: The mechanical vibration spectrum is a frequency-domain characteristic used for monitoring various systems and is traditionally calculated by the Fast Fourier Transform (FFT) of a time series. Another possible alternative, with several operational advantages, is the use of twin-microaccelerometers to obtain the spectrum directly in the frequency domain. This strategy has its greatest limitation in the differences found in the accelerometers physical parameters -- due to their manufacturing process --, such that the spectrum distortion level may be considerably higher than that found in the spectrum raised by the FFT. To overcome these differences, in this work the tuning of the spectrum analyzer microdevice is proposed by adjusting the accelerometers actuation voltages amplitudes. To perform the tuning, the Differential Evolution (DE) is used and the tuning problem is approached in two different optimization perspectives: a mono-objective and a multi-objective. For both optimization problems, the objective functions and constraints are based on the Fourier series components of the spectrum analyzer system closed-loop gain -- a composition that depends on the excitation voltages. To solve the multi-objective optimization problem, the DE algorithm is properly adapted. The advantages and disadvantages of both tuning strategies are discussed in detail, as well as the results obtained for the Pareto-set approximation. The results -- specially the distortion-sensitivity compromise -- are demonstrated and discussed. The validity of the proposed tuning strategy is evidenced, since it is able to determine the voltages amplitudes to be applied to the micro spectrum analyzer to attend the distortion level and sensitivity requirementsMestradoAutomaçãoMestra em Engenharia Elétrica161153/2018-6CNP

    Climbing and Walking Robots

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    Nowadays robotics is one of the most dynamic fields of scientific researches. The shift of robotics researches from manufacturing to services applications is clear. During the last decades interest in studying climbing and walking robots has been increased. This increasing interest has been in many areas that most important ones of them are: mechanics, electronics, medical engineering, cybernetics, controls, and computers. Today’s climbing and walking robots are a combination of manipulative, perceptive, communicative, and cognitive abilities and they are capable of performing many tasks in industrial and non- industrial environments. Surveillance, planetary exploration, emergence rescue operations, reconnaissance, petrochemical applications, construction, entertainment, personal services, intervention in severe environments, transportation, medical and etc are some applications from a very diverse application fields of climbing and walking robots. By great progress in this area of robotics it is anticipated that next generation climbing and walking robots will enhance lives and will change the way the human works, thinks and makes decisions. This book presents the state of the art achievments, recent developments, applications and future challenges of climbing and walking robots. These are presented in 24 chapters by authors throughtot the world The book serves as a reference especially for the researchers who are interested in mobile robots. It also is useful for industrial engineers and graduate students in advanced study

    Intelligent Systems

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    This book is dedicated to intelligent systems of broad-spectrum application, such as personal and social biosafety or use of intelligent sensory micro-nanosystems such as "e-nose", "e-tongue" and "e-eye". In addition to that, effective acquiring information, knowledge management and improved knowledge transfer in any media, as well as modeling its information content using meta-and hyper heuristics and semantic reasoning all benefit from the systems covered in this book. Intelligent systems can also be applied in education and generating the intelligent distributed eLearning architecture, as well as in a large number of technical fields, such as industrial design, manufacturing and utilization, e.g., in precision agriculture, cartography, electric power distribution systems, intelligent building management systems, drilling operations etc. Furthermore, decision making using fuzzy logic models, computational recognition of comprehension uncertainty and the joint synthesis of goals and means of intelligent behavior biosystems, as well as diagnostic and human support in the healthcare environment have also been made easier

    Proceedings of the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008

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    This volume contains full papers presented at the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008, held in Braga, Portugal, between September 4th and 6th, 2008.FC
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