Wave Scattering
Mostrando 13-24 de 71 artigos, teses e dissertações.
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13. Autoionization of He atoms induced by partially stripped ion impact
A study of the autoionization process induced by partially stripped ion impact is performed. The Barrachina-Macek model is extended to the case in which the projectile-emitted electron interaction is represented by means of a non-Coulombic central potential at all times. Electron spectra in momentum space are predicted and compared to the Barrachina-Macek mo
Brazilian Journal of Physics. Publicado em: 2010-03
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14. Gas de Bose diluido fracamente confinado / Dilute Bose gas weakly confined
A critical study of atomic Bose-Einstein condensates (BECs) is presented. Taking as a starting point the physics of the free gas, we study the effect of weakly confining potentials. Two cases were studied in detail: i) an atomic gas in a finite square well potential with a few bound states; and ii) a system confined in two-dimensions by an isotropic harmonic
Publicado em: 2010
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15. Espalhamento de ondas eletromagnéticas por esferas e cilindros magnéticos: confinamento e transporte de ondas no limite de pequenas partículas e independência da energia armazenada com relação à forma do centro espalhador / Electromagnetic wave scattering by magnetic spheres and cylinders: waves confinement and transport in the small particle limit and independence of the stored energy with respect to the shape of the scatterer
O espalhamento eletromagnético por uma esfera com propriedades ópticas e raio arbitrários, conhecido como espalhamento de Lorenz-Mie, ou por um cilindro circular infinito, pode ser resolvido analiticamente e é comumente tratado dentro da abordagem de espalhadores dielétricos. Na região óptica, tanto meio circundante quanto partícula espalhadora possu
Publicado em: 2010
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16. First principle calculation of potential and multi-channel transport in Fe/MgO/Fe hetero-junction
In this work we studied the behavior of multi-channel tunneling through a realistic Fe/MgO/Fe hetero-junction ab initio potential. For this purpose we obtained Fe/MgO/Fe(001) hetero-junction effective potentials using the full potential-linear augmented plane wave WIEN2k code together with the generalized gradient approximation for the exchange-correlation p
Brazilian Journal of Physics. Publicado em: 2009-04
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17. Modelagem Computacional da Propagação Acústica Proveniente de Fontes Multifrequênciais Usando Guias Digitais de Ondas / Computational Modeling of Wave Propagation from Multifrequêncial Source Using Mesh Digital Waveguide
The goal of this research is the creation of virtual acoustic environments, in this context, was constructed a computational tool, aiming to the acoustic modeling of reverberation environment. In this way, it was necessary to elaborate a numerical system able to simulate the wave sound propagation and, mainly its interactions with the surfaces encountered in
Publicado em: 2009
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18. SYNTHESIS AND ANALYSIS OF CIRCULARLY SYMMETRIC REFLECTORS VIA PHYSICAL OPTICS AND FRINGE WAVE CURRENTS / ANÁLISE E SÍNTESE DE REFLETORES CIRCULARMENTE SIMÉTRICOS PELOS MÉTODOS DA ÓTICA FÍSICA E CORRENTES DE FRANJA
The usual algorithms employed in the design of shaped reflector antennas for satellite applications embed an electromagnetic analysis method in an optimization technique. In general, these algorithms demand considerable computation time, limiting its intensive use in the study to explore different sets of specifications and to search for more compact geometr
Publicado em: 2009
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19. The role of crossing symmetry for a low energy pion-nucleon scattering from dispersive method
The slow convergence of chiral perturbation theory for heavy baryons (HBChPT) suggests that any attempt to unitarize the amplitude following from this method will fail to describe the experimental phase shifts. However, it was possible to obtain a ChPT pion nucleon amplitudes respecting exact unitarity relation by using the Inverse Amplitude Method (IAM), bu
Brazilian Journal of Physics. Publicado em: 2008-09
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20. Propagação e espalhamento de odas escalares em espaços-tempos de dimensões superiores
In this Dissertation we study the scattering of massless monochromatic scalar waves by 5-dimensional (5D) Schwarzschild-Tangherlini black holes. We compute the scattering phase shifts using Prüfer method for high frequencies and high-values of the angular multipole index l. The phase shifts are then used to analyze the glory effect, in comparison with the r
Publicado em: 2008
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21. Propriedades eletrônicas de nanofios semicondutores / Electronic properties of semiconductor nanowires
We have performed an extensive study on the electronic and structural properties of silicon nanowires (NWs) using parameter free computational simulations (DFT). We show that in Si NWs, surfaces whose atoms are connected to inner ones perpendicularly to the wires axes become electronically inactive at the band edges. However, when these bonds are oriented al
Publicado em: 2008
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22. High sensitivity Thermal Lens spectroscopy / Espectroscopia de lente térmica de alta sensibilidade
The efficiency of conventional transmission methods used to measure absorption of hightransparent materials is usually limited by light scattering and reflection. On the other hand, Thermal Lens spectroscopy is insensible to such phenomena and has been widely applied to determinate low optical absorptions. In this thesis, we have studied a recently developed
Publicado em: 2008
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23. Análise de antenas refletoras circularmente simétricas com a presença de corpos dielétricos
This work develops theoretical, analytical and numerical tools for solution of electromagnetic scattering from bodies of revolution, composed by perfect conductors and dielectrics, such as reflector antennas with radomes. Accurate analyses of these structures are performed through algorithms based on electric and magnetic integral equations, numerically eval
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 04/05/2007
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24. BK equation and traveling wave solutions
It has been shown that the transition to the saturation regime of high energy QCD is similar to the formation of the front of a traveling wave. In particular, it can be verified that Balitsky-Kovchegov (BK) evolution equation reduces, after some approximations, to the nonlinear Fisher and Kolmogorov-Petrovsky-Piscounov (FKPP) equation, well-known from statis
Brazilian Journal of Physics. Publicado em: 2007-07