ISSN:0041-1450    

DOI:10.1080/00411458208230834

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Riemann-Hilbert problems arising in two-group neutron transport theory and linearly anisotropic scattering, connected with half-space homogeneous media, are considered. A detailed procedure for obtaining a fundamental matrix for the case of the same total cross sections in both groups is given following a recent idea of Cercignani. Next, a first order correction to the fundamental matrix is obtained by applying a perturbation technique with respect to the difference between total cross sections as an expansion parameter. Stability of the total index to the Riemann-Hilbert problem is also considered.

ISSN:0041-1450    

DOI:10.1080/00411458208230835

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The standard iterative procedure for solving fixed-source discrete-ordinates problems converges very slowly for problems in optically thick regions with scattering ratios c near unity. The diffusion-synthetic acceleration method has been proposed to make use of the fact that for this class of problems, the diffusion equation is often an accurate approximation to the transport equation. How-ever, stability difficulties have historically hampered the implementation of this method for general transport differencing schemes In this article we discuss a recently developed procedure for obtaining unconditionally stable diffusion-synthetic acceleration methods for various transport differencing schemes. We motivate the analysis by first discussing the exact transport equation; then we illustrate the procedure by deriving a new stable acceleration method for the linear discontinuous transport differencing scheme. We also provide some numerical results.

ISSN:0041-1450    

DOI:10.1080/00411458208230836

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Transport calculations presented here are of photoelectron fluxes and energy spectra in the ionosphere for electrons along the magnetic field lines of the earth in an inhomogeneous anisotropically scattering atmosphere, which takes account of elastic, and inelastic collisions, and energy loss to ambient plasma. The transport fluxes at low altitudes are found to be lower than the local fluxes, while at high altitudes the transport fluxes are higher than the local fluxes. Results of our calculations are given and compared with the experimental data obtained from NASA Satellite Explorer C. The methodology used here is relatively new, interesting and powerful.

ISSN:0041-1450    

DOI:10.1080/00411458208230837

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor