摘要:

The present paper deals with the fine structure of the real point spectrum of a class of transport operators with unsymmetric scattering kernels. We give necessary and sufficient conditions for existence, finiteness and sufficient conditions for infiniteness of the real point spectrum. Estimates of the number of eigenvalues and localization results are given.

ISSN:0041-1450    

DOI:10.1080/00411459308203834

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Numerical algorithms for the solution of the Boltzmann equation in multi-valley semiconductors with carrier-carrier (e-e) interactions are developed. These algorithms are treated as numerical methods solving a system of stochastic differential equations which approximates the Boltzmann equation. Numerical results showing the influence of e-e interactions on electron transport in n-GaAs are obtained.

ISSN:0041-1450    

DOI:10.1080/00411459308203835

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Adaptive characteristic spatial quadrature schemes for use in discrete ordinates neutral particle transport computer codes in slab geometry have been introduced recently; the extension to two-dimensional Cartesian coordinates with rectangular cells is presented here. These quadratures differ from previous schemes in using strictly non-negative finite-element-like representations of the entering fluxes and scattering source, which adapt to match both the zeroth and first spatial moments. (These input moments are obtained from the boundary conditions or as output moments of the upstream adjacent cells and from the angular quadrature of the spatial flux moments in the outer iteration, respectively.) The flux throughout the cell is found by integration of the transport equation along streaming (characteristic) lines. The moments of the flux through the cell and along the exiting boundaries are then obtained. The resulting quadratures are nonlinear and strictly non-negative, while satisfying zeroth-spatial-moment and first-spatial-moment balances within each cell and globally.

ISSN:0041-1450    

DOI:10.1080/00411459308203836

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The problem of uniformly valid asymptotic expansion for the singular perturbed Boltzmann equation in the limiting case of both small Knudsen and Mach numbers is being considered. The one-dimensional sound wave propagation is used as a control problem to find secular terms. The multivariable technique alone permits removing these terms and obtaining the time-uniformly valid asymptotic representation. It also determines the essentially two-time character of relaxation processes in a simple gas. It is remarkable that the Burnett equations do not arise in this expansion.

ISSN:0041-1450    

DOI:10.1080/00411459308203837

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The spectrum of the transport operator A in a nonhomogeneous finite convex medium is discussed in consideration of anisotropic scattering and fission. The nonexistence of accumulation points of σ(A) in the open half plane (λ ∈ C|Reλ > – ess in f v∑ (r, v)}is proved, provided that the total collision frequencyv∑ (r, v) is piecewise continuous with respect to (r, v), the scattering—fission kernelk(r, v, Ω, v', Ω') is piecewise continuous with respect to (r, v, Ω, v', Ω') or has the formN(r)k(v, Ω, v', Ω').

ISSN:0041-1450    

DOI:10.1080/00411459308203838

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Singular integral equations defined over closed contours in the complex plane were treated in a previous paper by a generalization of the orthogonality method introduced into transport theory by Kuščer, McCormick and Summerfield. In this paper, we show how in some cases the solutions described in the previous work may be evaluated analytically.

ISSN:0041-1450    

DOI:10.1080/00411459308203839

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0041-1450    

DOI:10.1080/00411459308203840

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor