共查询到20条相似文献,搜索用时 31 毫秒
1.
The article investigates the convergence of an iterative method of solution of the integral equation for the diffraction problem of an electromagnetic field in a nonabsorbing medium. The convergence region of the iterative process is determined for the diffraction of a plane wave on a dielectric cylinder in a homogeneous space.Translated from Matematicheskie Modeli Estestvoznaniya, Published by Moscow University, Moscow, 1995, pp. 112–114. 相似文献
2.
E. V. Zakharov S. N. Levchenko Yu. Ya. Kharlanov 《Computational Mathematics and Modeling》1997,8(3):282-287
The article considers the mathematical model of a lens antenna in the shape of a homogeneous dielectric torus excited by an
axial magnetic dipole. The boundary-value problem for an elliptical differential equation is posed and reduced by the fundamental
solution method to an integral equation of 2nd kind over the torus section. A numerical algorithm is proposed, and the numerical
results are compared with experimental findings.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 109–115. 相似文献
3.
The inverse problem of electromagnetic sounding of the shape of a conducting body is considered in the framework of the two-dimensional
model with E-polarization, assuming a cylindrical body of an arbitrary cross section embedded in a layered medium. The integral
equations are obtained for the case of an ideally conducting body and a body of finite conductivity. The linearization method
is applied to obtain an iterative method that finds a correction to the initial shape.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 96–103. 相似文献
4.
A method is proposed for constructing the field of a point source in an axial two-dimensionally nonhomogeneous medium. The
problem is reduced to an integral equation of the 2nd kind. If the frequency ω of the point source is sufficiently high, the
equation can be solved by the method of successive approximations. The Neumann series converges in the usual sense for ω>>1
and it is an asymptotic series for ω→∞. The Neumann series also converges in the case of weak dependence of the medium on
the coordinate φ.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 104–108. 相似文献
5.
A new partial differential equation to be called the layered medium equation is introduced, and it is proved that certain relevant initial or periodic boundary conditions give well-posed problems. Then, the homogenized limit of the layered medium equation is studied. It is shown to be preserved in limit in the limit in the physical problem in which the coefficients that arise from the dielectric layer are both proportional to thickness. Otherwise, a non-local problem is obtained as the limiting form 相似文献
6.
Method of asymptotic perturbation of fundamental solution and electromagnetic waves in layered media
V. I. Selin 《Computational Mathematics and Modeling》1999,10(3):255-266
The method of asymptotic perturbation of the fundamental solution of the wave equation is applied to compute the rapidly oscillating
integrals that arise in wave fields in layered media. The principal part is separated for one of the integrals determining
the electromagnetic waves in a layer medium.
Translated from Chislennye Metody v Matematicheskoi Fizike, Moscow State University, pp. 53–66, 1998. 相似文献
7.
A. L. Kalamkarov B. A. Kudryavtsev V. Z. Parton 《Journal of Applied Mathematics and Mechanics》1991,55(6):844-852
An elliptic equation for a layered regularly inhomogeneous (composite) material serves as an example for the introduction of new integral transforms that enable boundary-value problems to be solved in quadratures, without the need to solve boundary-layer problems. These integral transforms are used to solve simple boundary-value problems for a layered composite and to obtain a fundamental solution of an elliptic equation in an infinite two-dimensional laminar medium. 相似文献
8.
V. I. Dmitriev P. S. Belkin N. A. Mershchikova 《Computational Mathematics and Modeling》2005,16(4):289-300
The article computes the electromagnetic field on the surface of a layered medium with a local nonhomogeneity. The problem
is transformed from three- to two-dimensional and the singulari-ties are investigated using the integral equation method.
The proposed algorithm efficiently sim-ulates two-dimensional H-polarization fields by solving a system of integral equations. The method is particularly effective for solving inverse problems.
__________
Translated from Prikladnaya Matematika i Informatika, No. 18, pp. 5–16, 2004. 相似文献
9.
V. F. Apel'tsin 《Computational Mathematics and Modeling》1997,8(4):369-384
An incomplete Galerkin projection method is constructed and proved as a generalization of the Sommerfeld method for the problem
of plane diffraction of the field of a point source on an ideally conducting circular cylinder coated by a thin homogeneous
dielectric layer with an arbitrary boundary, in the H-polarization case. An explicit asymptotic solution is obtained in the
form of a generalized Watson series. Specific eesonance phenomena are investigated for a boundary layer with corner points.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 132–149. 相似文献
10.
M. S. Kruglyakov 《Computational Mathematics and Modeling》2010,21(1):30-40
We consider the direct problem of aerial electric sounding for a layered medium with a vertical cylindrical anomaly. We determine
the minimum size of the anomaly when it is indistinguishable from an infinite layer of the same conductivity. The integral
equation is solved by the integral current method. The concept of apparent conductivity is introduced for sounding problems
using a magnetic dipole. The calculations support the conjecture of the locality of aerial sounding and prove the high efficiency
of the integral current method for such problems. 相似文献
11.
In this paper, we consider the inverse problem of recovering a doubly periodic Lipschitz structure through the measurement of the scattered field above the structure produced by point sources lying above the structure. The medium above the structure is assumed to be homogeneous and lossless with a positive dielectric coefficient. Below the structure is a perfect conductor partially coated with a dielectric. A periodic version of the linear sampling method is developed to reconstruct the doubly periodic structure using the near field data. In this case, the far field equation defined on the unit ball of ?3 is replaced by the near field equation which is a linear integral equation of the first kind defined on a plane above the periodic surface. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
The article examines the general Galerkin method scheme for the singular integral equation in the problem of radiation from
a finite-thickness linear radiator.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 150–158. 相似文献
13.
Fredholm equations of the first kind 总被引:2,自引:0,他引:2
A method is described for solving the Fredholm integral equation of the 1st kind by passage to the moment L-problem. The problem
is reduced to a linear programming problem. A bound of the method for a particular normed space is derived.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 34–38. 相似文献
14.
The paper examines the scattering of a Gaussian video signal by an ideally conducting circular cone coated with a dielectric
layer. The problem is solved by the method of integral equations for monochromatic waves at low and resonance frequencies
with subsequent Fourier transformation to the time domain. The response is investigated with signals propagating along the
symmetry axis from the direction of the apex and from the direction of the base for dielectric layers of various permittivities.
Translated from Chislennye Metody v Matematicheskoi Fizike, Moscow State University, pp. 46–52, 1998. 相似文献
15.
V. I. Dmitriev 《Computational Mathematics and Modeling》1997,8(3):270-277
We consider the inverse sounding problem for a stratified medium using the variable magnetic field of a loop. A uniqueness
theorem and a theorem ensuring stable determination of the integral conductivity of the medium are proved. An algorithm is
proposed for the solution of the inverse problem based on a transformation from the time domain to the frequency domain.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 87–95. 相似文献
16.
É. A. Al'khovskii I. V. Berezhnaya K. V. Grishin A. S. Il'inskii A. G. Kondrat'ev 《Computational Mathematics and Modeling》1996,7(2):180-184
A method is proposed for calculating the current distribution in an unsymmetric oscillator with several excitation points joined by a common distribution line. The radiator and the distribution line are represented by multipoles, which are described by scattering matrices. The elements of the radiator scattering matrix are calculated by the integral equation method. The calculation results are compared with experimental findings.Translated from Matematicheskie Modeli Estestvoznaniya, Published by Moscow University, Moscow, 1995, pp. 71–76. 相似文献
17.
This paper assembles a variety of methods which have been devisedfor acoustic and elastic wave propagation inverse problems andadapts them to the problem of determining the shear modulusprofile of an elastic half-space from a knowledge of the torsionaldeflection and shear stress distributions on the surface. Methodsinclude the reduction to a Gel'fand-Levitan integral equation,for which a fast numerical algorithm is presented; a methodbased on modelling the half-space as a layered medium; identificationof the medium as a member of a family for which a closed formsolution is possible; a Green's function approach for a mediumwith small variations from uniformity. 相似文献
18.
A nonlinear integrodifferential equation that arises in polaron theory is considered. The integral nonlinearity is given by a convolution with the Coulomb potential. Radially symmetric solutions are sought. In the semiclassical limit, an equation for the self-consistent potential is found and studied. The potential has a logarithmic singularity at the origin, and also a turning point at 1. The phase shifts at these points are determined. The quantization rule that takes into account the logarithmic corrections gives a simple asymptotic formula for the polaron spectrum. Global semiclassical solutions of the original nonlinear equation are constructed.Moscow Institute of Electronic Engineering; Moscow Power Institute. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 97, No. 1, pp. 78–93, October, 1993. 相似文献
19.
In this paper, a new integral equation of electrostatics is proposed as an integral form of a basic dielectric continuum model,
which is traditionally represented in a form of Poisson differential equation. As an application in protein simulations, the
new integral equation is reduced to a second kind Fredholm boundary integral equation on the interface between the solute
and solvent regions for a piecewise constant permittivity function, together with two new integral expressions for the electrostatics
within the solute and solvent regions. The new integral equation and expressions work for any charge problem over the whole
space (including the one with charges on the interface). This valuable feature is verified numerically for a dielectric sphere
model with a point charge inside, outside, or on the sphere in this paper. 相似文献
20.
This paper is concerned with the problem of heat conduction from an inclusion in a heat transfer layered medium. Making use of the boundary integral equation method, the well-posedness of the forward problem is established by the Fredholm theory. Then an inverse boundary value problem, i.e. identifying the inclusion from the measurements of the temperature and heat flux on the accessible exterior boundary of the medium is considered in the framework of the linear sampling method. Based on a careful analysis of the Dirichlet-to-Neumann map, the mathematical fundamentals of the linear sampling method for reconstructing the inclusion are proved rigorously. 相似文献