Electric Oscillations
Mostrando 1-12 de 31 artigos, teses e dissertações.
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1. Electric and magnetic field signatures of gravity waves and 2-day planetary waves in the equatorial E-region / Assinaturas nos campos elétricos e magnéticos às ondas de gravidade e ondas planetárias de 2-dias na região E equatorial
Equatorial electrojet (EEJ) observations using VHF radars show backscattered echoes from two types of electron density irregularities explained by the modified two-stream (Type I) and the gradient drift (Type 11) instabilities. From the Type II irregularity velocities obtained by radar data we have inferred the vertical electric fields (E_z). The harmonic an
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/02/2009
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2. Potential performance of SiC and GaN based metal semiconductor field effect transistors
A Monte Carlo simulation has been used to model steady-state electron transport in SiC and GaN field effect transistor. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible. Simulations of SiC MESFETs of lengths 2, 2.6 and 3.2 µm have been carried out and compared t
Brazilian Journal of Physics. Publicado em: 2009-03
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3. Magnetotransporte em poços-quânticos de AlGaAs/GaAs com diferentes formas de potencial / Magnetotransport in AlGzAs/GzAs quantum wells with different potential shapes
In this thesis we present studies of magnetotransport in double quantum wells (DQWs) in low magnetic fields and under application of an external electric field (gate potential). Measurements of magnetoresistance have been carried out in both linear and non-linear regime. We report on the observation of magneto-intersubband (MIS) oscillations for the first ti
Publicado em: 2009
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4. Utilização do elo de corrente continua para o amortecimento de oscilações eletromecanicas em sistemas eletricos de potencia / Use of the direct current link for the electromechanical oscillations damping in electric power systems
This dissertation presents a study about the HVDC (High Voltage Direct Current) link contribution for damping low frequency electromechanical oscillations when Electric Energy System suffers small-signal disturbances. The HVDC link components models were included in the Power Flow method as well as the steady-state characteristics of the dynamic devices (cur
Publicado em: 2009
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5. Assinaturas nos campos elétricos e magnéticos às ondas de gravidade e ondas planetárias de 2-dias na região E equatorial / Electric and magnetic field signatures of gravity waves and 2-day planetary waves in the equatorial E-region
Equatorial electrojet (EEJ) observations using VHF radars show backscattered echoes from two types of electron density irregularities explained by the modified two-stream (Type I) and the gradient drift (Type 11) instabilities. From the Type II irregularity velocities obtained by radar data we have inferred the vertical electric fields (E_z). The harmonic an
Publicado em: 2009
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6. Estabilização de oscilações de potencia de linhas de intercambio atraves de um elo de corrente continua / Stabilization of power lines interchange oscillations through a direct-current link
When an interconnected alternate-current power system suffers variations of loads, its frequency can exhibit an oscillatory behavior. If this system possesses a direct-current link in parallel with the inter-tie lines, this effect could be decreased, due to the link current controller action. This work presents a study that evaluates the efficiency of DC lin
Publicado em: 2009
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7. Diagnosis of the use of electric energy of slaugterhouse chicken emphasing action of energy efficiency / Diagnostico do uso de energia de um frigorifico de frangos de corte enfatizando medidas de eficiencia energetica
In the slaughterhouses the operations that if unchain in the one before slaughter until the storage of the end item are intensely dependents of the electric energy and answer for the final product quality. This work had as objective to diagnosis, to analyze and to consider solutions that lead to the rational use of the electric energy without intervening or
Publicado em: 2008
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8. Electromyographic pattern in lower limbs in response to postural perturbations / Padrão eletromiográfico de membros inferiores em resposta a perturbações posturais
Balance depends on the synergic activation of muscles bilaterally, and there is evidence that this coordination is mediated by spinal circuits, which are under supra-spinal control. The objective of this study is to describe neurophysiologic and biomechanical mechanisms involved in the postural control of healthy subjects submitted to a disturbance provoked
Publicado em: 2008
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9. Dois Elétrons em cadeias cristalinas e aperiódicas: efeito de campo elétricos.
Recently much attention was drived to the interplay between dynamical localization and electron-electron interaction. In this master degree thesis we contribute to futher understanding of the phenomenon of electronic Bloch oscillations in both periodic and apperiodic low-dimensional systems with two interacting electrons. We followed two distinct quantum for
Publicado em: 2007
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10. Robust control of FACTS devices to damp oscillations in electric power systems / Controle robusto de dispositivos FACTS para o amortecimento de oscilações em sistemas elétricos de potência
Este trabalho apresenta um método sistemático para projeto de controladores suplementares para um tipo de dispositivo FACTS (o modelo TCSC) para o amortecimento de oscilações em sistemas elétricos de potência. Adota-se uma metodologia previamente desenvolvida para projeto de apenas controladores de tipo PSS. Tal metodologia é fundamentada na teoria de
Publicado em: 2007
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11. Coherent properties and rabi oscillations in two-level donor systems
Coherent properties and Rabi oscillations in two-level donor systems, under terahertz excitation, are theoretically investigated. Here we are concerned with donor states in bulk GaAs and GaAs - (Ga, Al)As quantum dots. We study confinement effects, in the presence of an applied magnetic field, on the electronic and on-center donor states in GaAs - (Ga, Al)As
Brazilian Journal of Physics. Publicado em: 2006-06
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12. Modeling chaotic current oscillations in semi-insulating GaAs with rate-equations of impact ionization and field-enhanced trapping
We investigated the effect of adding the field-dependent recombination process, namely field-enhanced trapping, to the generation-recombination processes of charge carriers that model current oscillations in semiconductors. The main new features arising from this modification are identified in bifurcation diagrams with the electric field as the control param
Brazilian Journal of Physics. Publicado em: 2006-06