共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Elghazaly 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(3):482-491
The coupled conductive radiative transfer problem in two homogeneous layers slab of anisotropic scattering with specularly reflecting boundaries has been considered. A Galerkin-iterative technique is used to solve the coupled conductive radiative heat equations in integral forms for the two layers. Numerical results are obtained for the temperature, the conductive, radiative and the total heat fluxes for the two homogeneous layers with isotropic and anisotropic scattering. The calculations are also carried out for homogeneous plane parallel medium with anisotropic scattering which show good agreement with the published calculations. 相似文献
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V.V. Kocharovsky VI.V. Kocharovsky 《Physica C: Superconductivity and its Applications》1992,200(3-4):385-402
The Green's function method and diagram technique for umklapp electron-electron scattering mediated by the screened Coulomb interaction in layered anisotropic conductors are examined. Gor'kov-type equations and their general solution for anomalous and normal temperature Green's functions are derived taking into account umklapp scattering of all orders. Explicit equations for dielectric and superconducting order parameters, including coexistent Bragg and BCS pairing, are found. The possibility of the first-order phase transition to the superconducting state is discussed. The theory elucidates the origin of Bragg-Coulomb high-Tc superconductivity, proposed by the authors. 相似文献
4.
E. Z. Gribova 《Acoustical Physics》2011,57(3):359-367
Closed integrodifferential equations are derived for the coherence function and the ray intensity in the ocean. Random inhomogeneities
of the medium are assumed to be large-scale and statistically anisotropic. The influence of anisotropy on the angular scattering
pattern is analyzed. 相似文献
5.
Numerical 1D-3V solutions of the Wong-Yang-Mills equations with anisotropic particle momentum distributions are presented.
They confirm the existence of plasma instabilities for weak initial fields and of their saturation at a level where the particle
motion is affected, similar to Abelian plasmas. The isotropization of the particle momenta by strong random fields is shown
explicitly, as well as their nearly exponential distribution up to a typical hard scale, which arises from scattering off
field fluctuations. By variation of the lattice spacing we show that the effects described here are independent of the UV
field modes near the end of the Brioullin zone. 相似文献
6.
He-Ping Tan 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,87(2):175-192
It is not by isotropic scattering but by anisotropic scattering that radiant energy is redistributed in some materials containing real particles, fibers, or impurities. In some instances, great difference can be caused in transient thermal behavior between isotropic scattering and anisotropic scattering media. Ray tracing method combined with Hottel's zonal method is introduced to deduce thermal radiative source term for various optical boundary conditions induced by collimated incidence passing through translucent boundary. Temperature response caused by laser pulse at non-incident side of participating and anisotropic scattering media is examined. We investigate effects of scattering albedo, scattering phase function, initial temperature of media and thickness of media on temperature response. Results obtained for anisotropic scattering media are compared with those for isotropic scattering one and show that anisotropic scattering must be considered in the simulating measurement of thermophysical properties by the laser flash method for some materials with big scattering albedo which behave anisotropically, or big error will be introduced; forward scattering can increase excess temperature and backward scattering can decrease it at non-incident side of the considered sample irradiated by laser pulse. 相似文献
7.
A.L. Crosbie R.G. Schrenker 《Journal of Quantitative Spectroscopy & Radiative Transfer》1982,28(6):507-526
The equations for the source function, flux, and scattered intensity normal to the surface are formulated in cartesian coordinates for a 3-D rectangular absorbing, emitting, isotropically scattering medium exposed to both diffuse and collimated radiation. Simplifications of these equations for certain important geometries and uniform loading are presented. Also, superposition of these equations and radiative equilibrium are discussed. For pure scattering, the source function at the center of the square and cubic geometries is analytically determined for the diffuse boundary condition. The generalized 3-D equations are shown to reduce to the familiar 1-D results. Also, the equations for a strongly anisotropic phase function which is made up of a spike in the forward direction superimposed on an otherwise isotropic phase function are expressed in terms of the isotropic expressions. 相似文献
8.
R.O. Buckius M.M. Tseng 《Journal of Quantitative Spectroscopy & Radiative Transfer》1978,20(4):385-402
Radiation heat transfer in an absorbing, emitting and scattering medium has been the subject of many previous investigations. Most solutions are numerically complex and the existing analytical solutions are restricted in application by the simplifying assumptions involved. A plane-parallel medium is considered which scatters anisotropically. The boundaries are considered to be specular reflectors, as predicted by Fresnel's relations, while the diffusely incident radiation is refracted according to Snell's law. The emission is restricted to a medium with a uniform temperature distribution. Approximate closed-form solutions for the radiative heat flux and incident intensity are presented for dielectric layers and linear anisotropic scattering. Numerical results are also presented and show that the effects of directional boundaries, anisotropic scattering, scattering albedo and optical depth are accurately predicted by the approximate solution. 相似文献
9.
N. J. McCormick R. Sanchez 《Journal of Quantitative Spectroscopy & Radiative Transfer》1983,30(6):527-535
The equation of transfer for a plane-parallel medium is used to derive two independent sets of algebraic equations that can be used to determine the basic parameters that define the phase matrix for Lth degree anisotropic scattering of polarized light. The equations require that the four Stokes parameters be measured only on the surfaces of the medium that can be optically thick. There are (3L + 2) equations in each set for a general source distribution. 相似文献
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Edward F. Redish 《Nuclear Physics A》1974,235(1):82-122
The recently derived connected kernel equation (CKE) for N-body scattering operators is applied to direct nuclear reactions. A spectral representation is derived for the kernel of the CKE in order to obtain manageable approximations. This allows the kernel to be split into orders corresponding to the propagation of different numbers of bound clusters. By formally solving one part of the kernel at a time, the CKE is written as a hierarchy of nested equations in increasingly many variables. The first equation of this hierarchy is a set of coupled channel Lippmann-Schwinger equations coupling together all two-cluster channels. These equations reduce to the usual coupled channel equations for inelastic scattering and to the coupled channel Born approximation for rearrangement reactions when weak coupling assumptions are made. The second equation of the hierarchy is a two-variable integral equation for the effective interactions appearing in the coupled channel equations. The driving terms and kernel of this integral equation are obtained from the third equation of the hierarchy which is a three-variable integral equation and so forth. The use of the spectral expansion results in a renormalized theory in the sense that the bound state and reaction problems are separated. This permits the inclusion of nuclear models in the theory in a straightforward manner. The hierarchy is applied to a particular example, that of nucleon-nucleus scattering. For this case the hierarchy is truncated at the level allowing no more than three clusters in the continuum. By suppressing exchange and keeping only one-particle transfer and single-nucléon knockout channels, a set of equations for the optical potentials and transfer operators is obtained. These equations provide a three-body treatment of the single scattering approximation to the optical potential. Iteration of the equations yields the usual single scattering approximation in first order including three-body off-shell effects. After suppression of Fermi motion and off-shell effects, the standard impulse approximation is recovered. Modifications of the method for other cases are discussed and other possible applications suggested. 相似文献
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The kinetic equation for the case of anisotropic scattering of electrons by dislocations is written in the form of coupled algebraic equations for the expansion coefficients of the distribution function in spherical harmonics. The electrokinetic coefficient tensor is obtained for the case of arbitrarily oriented external fields. Departures from Matthiesen's rule due to anisotropy of the scattering process are obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 80–85, March, 1977. 相似文献
14.
H. Grissa F. Askri M. Ben Salah S. Ben Nasrallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(3):494-513
In this paper, the control volume finite element method (CVFEM) is applied for the first time to solve nonaxisymmetric radiative transfer in inhomogeneous, emitting, absorbing and anisotropic scattering cylindrical media. Mathematical formulations as well as numerical implementation are given and the final discretized equations are based on similar meshes used for convective and conductive heat transfer in computational fluid dynamic analysis. In order to test the efficiency of the developed method, four nonaxisymmetric problems have been examined. Also, the grid dependence and the false scattering of the CVFEM are investigated and compared with the finite volume method and the discrete ordinates interpolation method. 相似文献
15.
Low energy ion scattering (< 2 keV) in combination with LEED allows surface structure analysis in the case of gases adsorbed on single crystal surfaces. Strong shadowing and anisotropic effects observed are used to estimate the position of the adsorbed species. These techniques may also be extended to study adsorption on polycrystals. For the study of the faces of polar crystals multiple scattering effects in conjunction with shadowing offer a method of surface structure analysis. Surface relaxation effects may possibly be successfully measured by high energy (100 keV – 2 MeV) ion scattering making use of channelling and blocking effects. 相似文献
16.
Using the tadpole improved Wilson quark action on small, coarse,
and anisotropic lattices, meson-meson scattering lengths are
calculated within quenched approximation. The study covers
pion-pion scattering in the I=2 channel and kaon-pion scattering
in the I=3/2 channel. The results are extrapolated towards the
chiral limit. Finite volume and finite lattice spacing errors are
also analyzed and results in the infinite volume and continuum
limit are obtained. Our results are compared with the results
obtained using Roy equations, chiral perturbation theory,
dispersion relations, and the experimental data. We also compare
our results with other lattice results on the scattering lengths. 相似文献
17.
Maxwell equations are solved in a layer comprising a finite number of homogeneous isotropic dielectric regions ended by anisotropic perfectly matched layers (PMLs). The boundary-value problem is solved and the dispersion relation inside the PML is derived. The general expression of the eigenvalues equation for an arbitrary number of regions in each layer is obtained, and both polarization modes are considered. The modal functions of a single layer ended by PMLs are found, and their orthogonality relation is derived. The present method is useful to simulate scattering problems from dielectric objects as well as propagation in planar slab waveguides. Its potential to deal with more complex problems such as the scattering from an object with arbitrary cross section in open space using the multilayer modal method is briefly discussed. 相似文献
18.
The high field strength of femtosecond laser pulses leads to nonlinear effects during the interaction with condensed matter. One such effect is the ablation process, which can be initiated below the threshold of common thermal ablation if the excitation pulses are sufficiently short. This effect leads to structure formation, which is anisotropic because of the polarization properties of the near field and can result in pattern sizes below the resolution limit of light. These effects are explored by temporally resolved scattering methods and by post‐mortem analysis to show the non‐thermal and anisotropic nature of this process. The near‐field distribution of plasmon modes can be tailored to a large extent in order to obtain control of the pattern formation. 相似文献
19.
散射介质中层间杂质检测是一个非常重要的研究课题.改进现有的Monte Carlo方法,模拟大量光子在散射介质中的传输,得到入射光强、杂质埋藏深度、介质折射率、介质散射系数和各向异性因子对光学透反射成像法检测层间杂质效率的影响规律.结果表明,入射光强、杂质埋藏深度和介质折射率对透反射成像检测结果均有影响,且影响规律相似.增加入射光强、减小杂质埋藏深度或减小介质折射率均可提高反射光成像的检测效率;增大入射光强、减小介质折射率、减小介质散射系数或增大各向异性因子均可提高透射光成像的检测效率.这些规律对散射介质中层间杂质检测具有一定指导意义. 相似文献
20.
We investigate the analytical expression of the spectrum that is produced by scattering of a polychromatic plane light wave incident upon a rotational anisotropic particle. It is found that the appearance of extrema in the frequency shift of the scattered field can be exactly predicted by our derived equations of the rotation angle. Numerical examples are presented to illustrate the theoretical results and also to show the impact of the effective radius of the scattering potential on the frequency shift. 相似文献