Amplitude Modulation
Mostrando 25-36 de 286 artigos, teses e dissertações.
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25. Modulação autonômica cardíaca: influência da aptidão aeróbia, nível de atividade física e idade / Cardiac autonomic modulation: influence of the aerobic fitness, physical activity level and age
O sistema nervoso autônomo (SNA) modula a freqüência cardíaca (FC) em situações de repouso e dinâmicas. Em repouso a variabilidade da freqüência cardíaca (VFC) é uma ferramenta não invasiva para avaliação do SNA. Em situação dinâmica, a transição repouso exercício (Ton) e testes provocativos como manobra postural ativa (MPA) são capazes
Publicado em: 2010
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26. Detección de perturbaciones en soldadura basado en el monitoreo de la acústica aerotransportada del proceso MIG / MAG
The welding process's sound is a consequence of the modulation in amplitude of the current for the voltage of the electric arc. Previous experiments demonstrated that an experienced welder has an absolute dependence of the acoustics in the control of the welding process. In this work a new technique of detection of welding defects is presented based on the s
Soldagem & Inspeção. Publicado em: 2009-06
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27. Development of strongly modulated pulses for quantum information processing via Nuclear Magnetic Resonance / Utilização de pulsos de radiofrequência fortemente modulados no processamento de informação quântica via ressonância magnética nuclear
This dissertation presents the development and use of radiofrequency pulses simultaneously modulated in frequency, amplitude and phase (Strongly Modulated Pulses, SMP) for creating initial states and executing logical operations used as building blocks for Quantum Information Processing via Nuclear Magnetic Resonance (NMR-QIP). The experimental implementatio
Publicado em: 2009
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28. Estudo numÃrico do acoplador duplo simÃtrico de fibras Ãpticas operando com PPM e PAM para obtenÃÃo de portas lÃgicas / Numerical study of symmetrical double coupler for fiber optic operating with PPM and WFP to obtain gate
Neste trabalho, foram investigadas as caracterÃsticas de operaÃÃo de um Acoplador Direcional NÃo-Linear(NLDC) Duplo SimÃtrico, trabalhando com pulsos de , em duas diferentes aplicaÃÃes: ObtenÃÃo de portas lÃgicas E e OU, sob ModulaÃÃo Por PosiÃÃo de Pulsos (PPM); obtenÃÃo de portas lÃgicas E e OU, sob ModulaÃÃo Por Amplitude de Pulsos (PAM
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 22/01/2008
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29. Glass Difractive Optical Elements (DOEs) with complex modulation DLC thin film coated
We developed a complex (amplitude and phase) modulation Diffractive Optical Element (DOE) with four phase levels, which is based in a glass substrate coated with DLC (Diamond Like Carbon) thin film as the amplitude modulator. The DLC film was deposited by magnetron reactive sputtering with a graphite target and methane gas in an optical glass surface. The gl
Materials Research. Publicado em: 2008-09
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30. Modulation of cosmic rays at different cutoff rigidity
The present work deals with the study of first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period 1981-1993 for Deep River and Inuvik neutron monitoring stations having mid and low cutoff rigidity. The amplitude of first harmonic remains high for Deep River having mid cutoff rigidity as compared to Inuvik neutron monitor h
Brazilian Journal of Physics. Publicado em: 2008-03
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31. Generalized scalar modulation strategy for matrix converters / EstratÃgia de modulaÃÃo escalar generalizada para conversores matriciais
Power processors are devices capable to convert a set of voltages, with fixed amplitude and frequency, in other set, with controlled amplitude and frequency. The main function of these processors is to work as an adjustable power supply. The direct power converters are a class of power processors. They have significant advantages compared with the traditiona
Publicado em: 2008
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32. Modulação dos genes de relógio Per1, Cry1b, Clock e da melanopsina por endotelina-1 em células embrionárias de Danio rerio / Modulation of clock genes Per1, Cry1b, Clock and of melanopsin by endothelin-1 in Danio rerio embryonic cells
Biological clocks are endogenous timekeepers that are present both in eukaryotic as in prokaryotic organisms. Different clocks have different periods, and those that have about 24h of oscillation are called circadian clocks. In mammals, the first identified circadian clock is located in the suprachiasmatic nucleus, in the hipothalamus. It is now well known t
Publicado em: 2007
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33. Sobre equalizadores autodidatas de decisão realimentada aplicados a sistemas multiusuário
Due to the growing demand for mobile communications, adaptive equalizers play an important role for enhancing the efficiency of data transmission. In this scenario, the Decision Feedback Equalizer (DFE) stands out. It presents a favorable tradeoff between computational cost and efficient behavior, mainly when compared to Linear Transversal Equalizer. In this
Publicado em: 2007
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34. Fabricação de elementos ópticos difrativos de modulação completa. / Complex modulation diffractive optical elements fabrication.
Neste projeto foram desenvolvidos elementos ópticos difrativos fabricados em vidro óptico com modulação de fase, elementos fabricados em silício e em Diamond Like Carbon (carbono tipo diamante) com modulação completa de fase e amplitude. O vidro óptico começa a transmitir em 277 nm (ultravioleta) e vai até o infravermelho próximo (2200 nm) da mesm
Publicado em: 2007
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35. AnÃlise e resultados experimentais de sistemas de distribuiÃÃo quÃntica de chaves usando fÃtons isolados e estados coerentes mesoscÃpicos. / Theorical analysis and experimental results of quantum key distribution systems using single-photons and mesoscopic coherent states
In this dissertation it is realized a study about quantum key distribution (QKD) in optical networks. Initially, a review of the theory of quantum key distribution and some of its implementations with strongly attenuated coherent states, as well a review of an optical system for physical encryptation using mesoscopic coherent states are realized. Following,
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 13/09/2006
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36. Effects of effective mass discontinuity on the conductance of three-dimensional quantum wires
We calculate the conductance of three-dimensional semiconductor quantum wires considering different effective masses in the contacts and in the channel. We show that, with respect to the case with equal masses in the channel and in the contacts, the amplitude of the conductance oscillations increases if the electron effective mass in the channel is larger an
Brazilian Journal of Physics. Publicado em: 2006-09