Self Excitation
Mostrando 13-24 de 43 artigos, teses e dissertações.
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13. Anomalous shift of the recombination energy in single asymmetric quantum wells
Self-consistent numerical calculation and photoluminescence (PL) measurements have been used to investigate the temperature dependence of the optical Stark effect in n-doped GaAs/AlGaAs single asymmetric quantum wells (SAQWs), grown by molecular beam epitaxy. In the low-temperature regime (5 to 40 K) a remarkable blue shift (9.8 meV) is observed in the PL pe
Brazilian Journal of Physics. Publicado em: 2002-06
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14. MAPEAMENTO DO VALOR ECONÔMICO DOS EQUIPAMENTOS DE COMPENSAÇÃO DE POTÊNCIA REATIVA / ECONOMIC VALUE OF REACTIVE POWER DEVICES
No novo modelo para o setor elétrico brasileiro a operação do sistema é de responsabilidade do Operador Independente do Sistema enquanto que a propriedade do equipamento e os gastos com a sua manutenção são de responsabilidade do agente prestador do serviço ancilar.Desta forma, o lucro do agente prestador do serviço ancilar de potência reativa ser�
Publicado em: 2002
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15. Propriedades Ópticas de Semicondutores Orgânicos à Base de Polímeros Emissores de Luz / Optical proprieties of organic semiconductors based on light emitting polymers.
In this work, we studied the optical proprieties of absorption and emission of luminescent conjugated polymers based on poly(p-phenylene vinylene) (PPV). This material was processed in thin films by casting, spin-coating, self-assembled (SA) e Langmuir-Blodgett (LB) techniques, available in the Grupo de Polímeros Bernhard Gross, where the samples were chara
Publicado em: 2001
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16. UM MÉTODO PARA A ANÁLISE DA RESSONÂNCIA SUBSÍNCRONA DEVIDO A AUTO-EXCITAÇÃO / A METHOD FOR SUBSYNCHRONOURS RESONANCE ANALYSIS DUE TO SELF-EXCITATION
One of the methods used to increase power transfer capability is the partial compensation of the inductive reactance of lines through the use of series capacitors. This compensation, however, gives rise to subsynchronours resonance frequencies to appear in the system. Having as main objective of this work to present a method for subsynchronours resonance ana
Publicado em: 1981
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17. Self-excited mono-ion oscillator
We propose self-excitation as a potentially more sensitive technique for studying a mono-ion oscillator of frequency vz ≈ 0.1-100 MHz. This technique also makes only low demands on the harmonicity of the ion oscillation. It should therefore work with inexpensive, easily constructed rf traps. In our analysis, the bound ion between the trap electrodes is rep
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18. Vortex shedding as a precursor of turbulent electrical activity in cardiac muscle.
In cardiac tissue, during partial blockade of the membrane sodium channels, or at high frequencies of excitation, inexcitable obstacles with sharp edges may destabilize the propagation of electrical excitation waves, causing the formation of self-sustained vortices and turbulent cardiac electrical activity. The formation of such vortices, which visually rese
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19. Myxococcus xanthus fibril appendages are essential for excitation by a phospholipid attractant
Isolated (A-motile) Myxococcus xanthus cells glide over solid surfaces and display excitation, a suppression of direction reversals, when presented with phosphatidylethanolamine (PE) purified from its own membranes or synthetic dilauroyl PE and dioleoyl PE. Although the mechanism of PE signal transduction is unknown, we hypothesized that M. xanthus migh
The National Academy of Sciences.
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20. Unstable spiral modes in disk-shaped galaxies
The mechanisms for the maintenance and the excitation of trailing spiral modes of density waves in diskshaped galaxies, as proposed by Lin in 1969 and by Mark recently, are substantiated by an analysis of the gas-dynamical model of the galaxy. The self-excitation of the unstable mode in caused by waves propagating outwards from the corotation circle, which c
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21. The effects of reflex path length on clonus frequency in spastic muscles.
Clinical evaluation of clonus in spastic muscles was performed by comparing reflex path length with clonus frequency for different muscles in the same patient. It was found that clonus frequency varied inversely with reflex path length (r = 0.84, p less than 0.001). The findings confirm that clonus is generated by a peripheral mechanism of self re-excitation
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22. Birhythmicity, chaos, and other patterns of temporal self-organization in a multiply regulated biochemical system.
We analyze on a model biochemical system the effect of a coupling between two instability-generating mechanisms. The system considered is that of two allosteric enzymes coupled in series and activated by their respective products. In addition to simple periodic oscillations, the system can exhibit a variety of new modes of dynamic behavior; coexistence betwe
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23. Sustained vortex-like waves in normal isolated ventricular muscle.
Sustained reentrant excitation may be initiated in small (20 x 20 x less than 0.6 mm) preparations of normal ventricular muscle. A single appropriately timed premature electrical stimulus applied perpendicularly to the wake of a propagating quasiplanar wavefront gives rise to circulation of self-sustaining excitation waves, which pivot at high frequency (5-7
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24. Theory and application of fluorescence homotransfer to melittin oligomerization.
Fluorescence homotransfer (electronic energy transfer between identical fluorophores) has the potential to quantitate the number of subunits in membrane protein oligomers. Homotransfer strongly depolarizes fluorescence emission as a result of intermolecular excitation energy exchange between an initially excited, oriented molecule and a randomly oriented nei