Scattering Theory
Mostrando 37-48 de 113 artigos, teses e dissertações.
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37. Discrete evolutions in quantum systems with noncommutative coordinates / "Evoluções discretas em sistemas quânticos com coordenadas não-comutativas"
Estudamos a Mecânica Quântica não-relativística de sistemas físicos caracterizados pela presença de um grau de liberdade extra, que não comuta com a coordenada temporal. Na linguagem da Geometria Não-Comutativa, tratamos de sistemas descritos por uma álgebra da forma F(Q) X "A IND."teta""(R X "S POT.1"), onde F(Q) é a álgebra de funções sobre o
Publicado em: 2006
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38. Desenvolvimento de um sistema de imageamento usando a tomografia por coerÃncia Ãptica no domÃnio temporal e de Fourier
In this dissertation, we describe the basic theory and details of the implementation of three experimental optical coherence tomography systems, two in the time domain and one in the spectral (Fourier) domain. Optical coherence tomography (OCT) is a non invasive optical imaging method, capable of producing cross-sectional images of materials and biological t
Publicado em: 2006
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39. Phase-shift definition for pion-nucleon scattering from chiral perturbation theory
Chiral Perturbation Theory is considered as a very precise method when applied to pion-nucleon scattering near threshold and in the unphysical region since in these cases the pion momenta are small. In this framework, third order calculation yields a non-relativistic scattering amplitude with nine free parameters. From the fact that the resulting partial-wav
Brazilian Journal of Physics. Publicado em: 2004-03
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40. Magnetotransport and Hall ferromagnetism in magnetic semiconductor heterostructures / Magneto-transporte e ferromagnetismo Hall em heteroestruturas semicondutoras magnéticas
Digital magnetic heterostructures (DMHs) are semiconductor structures with magnetic impurities (Mn) restricted to some planar arrangements (monolayers) regularly spaced. In the presence of an external magnetic field, the sp-d exchange interaction between the localized magnetic moments and the itinerant carriers is responsible for a giant spin splitting, of t
Publicado em: 2004
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41. Cinetica de foto e termoisomerização de azocompostos em matrizes polimericas
In this work we had been studied the photo and thermal isomerization processes of the azo dyes (4-Dimethyl aminoazobenzene (DAB); [4-(N-(2-hidroxiethyl)-N-ethyl)-4 -nitroazobenzene] (DR1); [4-(N-(2-hidroxiethyl)-N-ethyl)-2 -chlore-4 nitroazobenzene] (DR13)) searching to make correlation with rate constants and the viscosity of the polymeric solutions, the ef
Publicado em: 2004
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42. O potencial nucleon-nucleon e a troca de dois píons relativística / Nucleon-nucleon potential and the relativistic exchange of two pions
This work is devoted to the construction of a two-pion Exchange nucleon-nucleon potential in the framework of the relativist chiral perturbation theory, formulated by Becher and Leutwyler. In their study of pion-nucleon scattering they developed a method to regain the Power counting rules while keeping Lorentz invariance. These authors also Drew attention to
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 21/08/2003
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43. Transporte quântico em poços parabólicos largos / Transportation wide parabolic quantum wells
The gradual progress, or evolution, of the two-dimensional (2D) toward three-dimensional (3D) Landau states was studied in wide parabolic quantum Wells (W = 1000 6000 Å). As transport technique, we used measurements of the magnetoresistence in intense (B = 0 15 T) and tilted ( = 0 90°; perpendicular parallel) magnetic Field at low temperature (T = 50 Mk).
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 25/07/2003
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44. Cálculo ab initio de intensidades Raman dinâmicas utilizando a teoria da resposta linear
In this paper a methodology for the computation of Raman scattering cross-sections and depolarization ratios within the Placzek Polarizability Theory is described. The polarizability gradients are derived from the values of the dynamic polarizabilities computed at the excitation frequencies using ab initio Linear Response Theory. A sample application of the
Química Nova. Publicado em: 2003-08
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45. Deflexão solar do gráviton-energia gravitacional em uma teoria não-simétrica da gravitação. / Solar gravitational deflection of a graviton - Ghost free analysis of a nonsymmetric theory of gravitation.
In this work two problems are studied, as summarized below: Part I - Deflection of the Solar Gráviton. This work calculated the deflection angle of the sun through the graviton your section of the shock of differential scattering. The term for the section of shock is obtained through a semi-classical theory. The result obtained for the angle of deflection o
Publicado em: 2003
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46. Efeitos de temperatura e de interação finita em sistemas desordenados correlacionados
The main goal of this work is to study the role of disorder in strongly correlated systems, where the electron-electron interaction is comparable to or dominates over the electron kinetic energy. Keeping this in mind, we solve the Hubbard model and the Anderson lattice model in the presence of disorder. The main theory in which our work is based is the Dynam
Publicado em: 2003
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47. Estudo de ordenamento multipolar eletrico de holmio por difração de raios-X
Multipolar ordering in metallic holmium 4f shell was extensively studied for the first time, by resonant and non resonant X-ray scattering at the helical antiferromagnetic and conical ferromagnetic phases. The strong spin-orbit coupling drives the multipolar order as it was experimentally confirmed through the temperature dependence of the ordering wave-vect
Publicado em: 2003
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48. P-Band radar data classification by neural network for Amazonin land cover assessment / Uso de rede neural artificial não supervisionada na classificação de dados de radar na Banda-P para mapeamento de cobertura da terra em floresta tropical
The applicability of P-band radar data for land cover mapping using the unsupervised artificial neural network Fuzzy-ART (Adaptive Resonance Theory) is evaluated. The study area is located near Tapajós National Forest in the State of Para, Brazil. The radar data was acquired during an airborne mission conducted by AeroSensing RadarSystem GmbH in september 2
Publicado em: 2003