Parabolic Equation
Mostrando 13-24 de 24 artigos, teses e dissertações.
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13. Spin valve effect and hall resistance in a wide parabolic well
We report observation of the Hall slope change in wide Al cGa1-cAs parabolic wells in the presence of a quasi-parallel magnetic field. Above the critical magnetic field B > 4T, the Hall resistance becomes temperature dependent and can be described by equation Rxy/costheta ~ (B-B0)/en s, where n s is the electron density, B0=2-2.6 T and theta is the angle bet
Brazilian Journal of Physics. Publicado em: 2006-06
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14. APPLICATION OF COMPUTATIONALLY-INTENSIVE PROPAGATION MODELS TO THE PREDICTION OF PATH LOSSES DUE TO MOUNTAINOUS TERRAIN IN THE VHF FREQUENCY BAND / APLICAÇÃO DE MODELOS COMPUTACIONALMENTE INTENSIVOS NA PREVISÃO DAS PERDAS DE PROPAGAÇÃO DEVIDAS A TERRENOS IRREGULARES NA FAIXA DE VHF
Os efeitos da difração na propagação de ondas de rádio sobre terreno irregular em VHF e outras bandas a ser usado por futuras aplicações da TV digital são normalmente estimados usando um dos muitos modelos clássicos. Nesta dissertação é feita uma comparação dos erros cometidos na previsão do sinal recebido por três modelos de propagação com
Publicado em: 2005
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15. Solidificação de ligas binarias : existencia de soluções de modelos do tipo campo de fase
In this work we present results of existence of solutions for some mathematical models of phase- field type for solidification of binary alloys. Firstly, we consider a model based on a highly non-linear degenerate parabolic system of partial differential equations, with three independent variables: phase-field, solute concentration and temperature. After tha
Publicado em: 2002
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16. Analise de solidificação em geometria cilindrica e a sua aplicação em armazenamento termico
In this work, a phase change thermal storage system of the shell and tube type is modelled. The phase change material is located in the shell and the heat transfer fluid is circulating in the tubes by forced convection. The system is solved using numerical and semi-analytical models. The numerical model consists of solving the momentum and energy equations u
Publicado em: 1999
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17. Strongly nonlinear parabolic initial-boundary value problems
An existence and uniqueness result is presented for the solution of a parabolic initial-boundary value problem under Dirichlet null boundary conditions for a general parabolic equation of order 2m with a strongly nonlinear zeroth-order perturbation. This is the parabolic generalization of a class of elliptic results considered earlier by the writers and othe
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18. DIRECT SOLUTION OF GENERAL ONE-DIMENSIONAL LINEAR PARABOLIC EQUATION VIA AN ABSTRACT PLANCHEREL FORMULA
We use the formalism of Fourier transformation to derive a functional calculus for the generator of an abstract group. As an application we obtain a new direct solution of Cauchy's problem for one-dimensional stationary parabolic equations of arbitrary order with bounded coefficients.
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19. New Integral Representations for Solutions of Cauchy's Problem for Abstract Parabolic Equations
A study has been made of Cauchy's problem for a class of abstract parabolic differential equations. Our study is based upon a transformation that maps solutions of second-order abstract Cauchy problems into solutions of first-order. This is a preliminary report on some of the results obtained. These results include (1) new representations for solutions of ab
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20. Self-similar intermediate asymptotics for a degenerate parabolic filtration-absorption equation
The equation ∂tu = u∂xx2u − (c − 1)(∂xu)2 is known in literature as a qualitative mathematical model of some biological phenomena. Here this equation is derived as a model of the groundwater flow in a water-absorbing fissurized porous rock; therefore, we refer to this equation as a filtration-absorption equation. A family of self-similar solutions
The National Academy of Sciences.
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21. Self-similar intermediate asymptotics for nonlinear degenerate parabolic free-boundary problems that occur in image processing
In the boundary layers around the edges of images, basic nonlinear parabolic equations for image intensity used in image processing assume a special degenerate asymptotic form. An asymptotic self-similar solution to this degenerate equation is obtained in an explicit form. The solution reveals a substantially nonlinear effect—the formation of sharp steps a
The National Academy of Sciences.
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22. The directional sensitivity of retinal rods.
Rod field sensitivity, 10-S(r) (i.e. the reciprocal of the radiance of a background required for 10-fold elevation of rod threshold) was measured for monochromatic backgrounds traversing the pupil at various points (r) on three subjects. The wave-length dependency of the directional sensitivities of the three foveal cone mechanisms of the principal subject h
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23. The flow of human blood through capillary tubes.
1. The current interpretation of in vivo blood flow is mainly based on the Hagen-Poiseuille equation, although blood is not a Newtonian fluid. In this paper, experimental pressure-flow curves of blood are explained on the basis that the viscosity of the blood is the sum of two components, a Newtonian viscosity term, N, and an anomalous viscosity term equal t
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24. Orthophosphate transport in the erythrocyte of normal subjects and of patients with X-linked hypophosphatemia.
We have examined the mechanism of TCA-soluble orthophosphate (Pi) transfer across the membrane of mature human erythrocytes in normal subjects and in patients with X-linked hypophosphatemia (X-LH). The studies were carried out largely at pH 7.4 and 37 degrees C, in partial stimulation of conditions in vivo. (a) At physiological concentrations (1-2 mM) Pi ent