Fast Fourier Transform
Mostrando 25-36 de 88 artigos, teses e dissertações.
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25. Construção e adequação de uma bancada de ensaios para investigações de técnicas não destrutivas de detecção de falhas incipientes em rolamentos
O monitoramento de vibração de máquinas rotativas é de grande interesse da indústria, uma vez que se tem a possibilidade de detectar, com certa antecedência, problemas relacionados à condição de funcionamento do equipamento, possibilitando reparos, ajustes ou consertos e, assim, minimizando custos no caso de falhas graves ou paradas inesperadas. Nes
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2012
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26. Avaliação de duas ferramentas para a representação das variáveis acústicas implicadas no vibrato da flauta.
This work investigated the flute vibrato, to determine which analytical tools that represent it in a more comprehensive way. Our aim is to use these tools to improve flute instrumental technic. After considering previously published works on this topic, it has been decided to focus this investigation on the following vibrato acoustical parameters: extent, ra
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 08/08/2011
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27. Acoplamento de técnicas espectrométricas com métodos quimiométricos de classificação e calibração multivariada em alimentos / Coupling spectrometric techniques with chemometric methods for classification and multivariate calibration in food
This research work describes three studies of chemometric methods employed for the classification and characterization of edible oils and its quality parameters through Fourier Transform mid infrared spectroscopy and near infrared spectroscopy, and for the monitoring the oxidative stability and quality of yogurt using fluorescence spectroscopy . The first an
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 06/05/2011
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28. Modelagem matemática de escoamentos bifásicos usando o Meto- Do Espectral de Fourier / Mathematics modeling of two-phase ows using spectral method of Fourier
A simulação numérica de escoamentos bifásicos requer alta acurácia para se obter maiores detalhes do escoamento. Além disso, busca-se baixo custo computacional, pois de modo geral, as metodologias necessitam de um elevado refinamento da malha ou possuem um grande estêncil de discretização, o que as torna onerosas. Portanto, o presente trabalho prop�
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 25/03/2011
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29. Numerical simulations of flows over a rotating circular cylinder using the immersed boundary method
In this paper, numerical simulations of incompressible flows around rotating circular cylinders have been performed. The two-dimensional Navier-Stokes equations are solved by using a Cartesian non-uniform grid. The Immersed Boundary Method (IBM) with the Virtual Physical Model (VPM) was used in order to model the presence of the circular cylinder in the flow
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2011-03
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30. EXPLORAÇÃO DE OPERADORES ARITMÉTICOS NA TRANSFORMADA RÁPIDA DE FOURIER / ARITHMETICS OPERATORS EXPLORATION IN FAST FOURIER TRANSFORM
The power consumption reduction in the fast Fourier transform (FFT) is important because applications in battery-powered embedded systems grows daily. Thus this work focuses on the application of techniques to reduce power in specific projects of FFT algorithms. The goal is to achieve an architectural exploration in the FFT core, the decimation in time butte
Publicado em: 2010
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31. Editorial
The aim of this present work was to provide a more fast, simple and less expensive to analyze sulfur content in diesel samples than by the standard methods currently used. Thus, samples of diesel fuel with sulfur concentrations varying from 400 and 2500 mgkg-1 were analyzed by two methodologies: X-ray fluorescence, according to ASTM D4294 and by Fourier tran
Eclética Química. Publicado em: 2010
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32. Solvolysis reactions of cation +SiCl3: Experiment and Theory / Reações de solvólise em fase gasosa do cátion +SiCl3: experimento e teoria
Polyhalogenated silicenium ions, X3Si+ (X = F, Cl), are common fragment ions in the mass spectra of polyhalogenated silanes obtained by electron ionization. These ions are powerful electrophiles and are believed to play a role in plasma enhanced corrosion processes and plasma enhanced chemical vapour deposition processes. In this dissertation, we present som
Publicado em: 2010
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33. Critical analysis of autoregressive and fast Fourier transform markers of cardiovascular variability in rats and humans
The autonomic nervous system plays an important role in physiological and pathological conditions, and has been extensively evaluated by parametric and non-parametric spectral analysis. To compare the results obtained with fast Fourier transform (FFT) and the autoregressive (AR) method, we performed a comprehensive comparative study using data from humans an
Brazilian Journal of Medical and Biological Research. Publicado em: 2009-04
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34. Teste de hipóteses sobre o espectro de freqüência, aplicado na manutenção preditiva de motores de indução
This project had begun with the aim of technical improvement and a predictive maintenance tool development for electrical machines diagnosis. Based on nonintrusive approach Motor Current Signature Analysis - MCSA for three-phase induction motor broken bars detection, it was developed a spectral analysis method able to increase accuracy and reliability, compa
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 21/08/2008
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35. Analise dinamica da interação solo-estrutura para estruturas superficiais utilizando a transformada implicita de Fourier (ImFT) / Dynamic analysis of soil-structure interaction for surface structures using the implicit Fourier transform (ImFT)
As características que determinam o comportamento de uma estrutura sob carregamento dinâmico são as massas dos vários elementos, a rigidez dos seus membros e a dissipação de energia. Para avaliar corretamente a resposta dinâmica de uma estrutura levando em conta os efeitos da interação, é necessário incorporar as propriedades dinâmicas do solo de
Publicado em: 2008
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36. Estudo da copolimerização em mini emulsão de metacrilato de metila/metacrilato de etila / Study of methyl methacrylate/ethyl methacrylate in mini emulsion copolimerization
Reduction of volatile organic compounds (VOC) usage is a constant environmental demand. Polymeric aqueous emulsion of low surfactant contends produced from direct miniemulsion synthesis are used with advantages to replace organic solvents media as well as aqueous emulsions of high surfactant concentration. Water as continuous phase and organic monomers with
Publicado em: 2008