共查询到19条相似文献,搜索用时 78 毫秒
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该文建立了手性障碍电磁散射问题的二维模型, 给出问题的有限元分析, 并利用结合PML(perfectly matched layers)技术的有限元法进行数值模拟. 相似文献
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Problems for electromagnetic scattering are of significant importance in many areas of technology. In this paper we discuss the scattering problem of electromagnetic wave incident by using boundary element method associated with splines. The problem is modelled by a boundary value problem for the Helmholtz eouation 相似文献
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§1Introduction Phenomenaofopticalactivityinspecialmaterialshavebeenknownsincethe beginningoflastcentury.Thoughopticalactivityhasbeenconsideredinopticsandin quantummechanicsformanyyears,itsanalysiswithintheframeworkofclassical electromagneticfieldtheoryarosemuchlater.Recently,therehasbeenaconsiderable interestinthestudyofscatteringanddiffractionbychiralmedium.Ingeneral,the electromagneticfieldsinsidethechiralmediumaregovernedbyMaxwellequations togetherwithDrude-Born-Fedorovequationsinwhichth… 相似文献
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陈国庆 《高等学校计算数学学报》2000,22(3):248-255
且引言考虑线性互补问题**P(q,M):求X二(X;,x。,…,x。厂E”使得x>O,训x)E*x+g>o,/U(X)一O(1)其中M一(m;。)为nXn矩阵(不必对称),q一切,q。,…,q。)rER“为给定常向量.通常情况下已有求解LCP(q,M)的若干著名算法[‘-’j.本文提出求解LCP(q,M)的一种新算法一行作用法,方法具有如下特点:(i)每次迭代只需n个简单的投影运算,每次投影只涉及矩阵M的一行;(n)生成新的迭代点x‘“‘时只利用前次迭代点/;(iii)对矩阵M不实施任何整体运算.因而适合于求解大型(巨型)稀疏问题,且… 相似文献
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声波障碍体的散射中(obstaucle scattering),由散射波的远场数据{u∞(■,d):■,d∈Sm-1}重构散射体是一个标准的逆散射问题.在单个散射体的情形,已经有了大量的研究工作.然而,如果所讨论的逆散射现象是由多个散射体引起的,则除了重建散射体的边界外,还需要确定不同散射体的边界类型.本文主要考虑用探测法重构两个不同类型散射体边界的数值实现.与以往单个散射体的探测方法相比,需要更为仔细地考虑针的选取和包含多个散射体的非凸性区域的构造.在构造指示函数时所需要的Neumann数据■Ω,是采取边界积分方程法直接求解Helmholtz混合边值问题得到的. 相似文献
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In this paper, we consider the electromagnetic scattering by a periodic chiral structure. The media is homogeneous and the structure is periodic in one direction and invariant in another direction. The electromagnetic fields inside the chiral medium are governed by Maxwell equations together with the Drude-BornFedorov equations. We simplify the problem to a two-dimensional scattering problem and discuss the existence and the uniqueness of solutions by an integral equation approach. We show that for all but possibly a discrete set of wave numbers, the integral equation has a unique solution. 相似文献
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A.G. Ramm Semion Gutman 《应用数学学报(英文版)》2005,21(3):399-404
Some difficulties are pointed out in the methods for identification of obstacles based on the numerical verification of tile inclusion of a function in the range of an operator. Numerical examples are given to illustrate theoretical conclusions. Alternative methods of identification of obstacles are mentioned: the Support Function Method (SFM) and the Modified Rayleigh Conjecture (MRC) method. 相似文献
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L. Fatone M. C. Recchioni F. Zirilli 《Journal of Optimization Theory and Applications》2004,121(2):223-257
In this paper, we consider furtivity and masking problems in time-dependent three-dimensional electromagnetic obstacle scattering. That is, we propose a criterion based on a merit function to minimize or to mask the electromagnetic field scattered by a bounded obstacle when hit by an incoming electromagnetic field and, with respect to this criterion, we drive the optimal strategy. These problems are natural generalizations to the context of electromagnetic scattering of the furtivity problem in time-dependent acoustic obstacle scattering presented in Ref. 1. We propose mathematical models of the furtivity and masking time-dependent three-dimensional electromagnetic scattering problems that consist in optimal control problems for systems of partial differential equations derived from the Maxwell equations. These control problems are approached using the Pontryagin maximum principle. We formulate the first-order optimality conditions for the control problems considered as exterior problems defined outside the obstacle for systems of partial differential equations. Moreover, the first-order optimality conditions derived are solved numerically with a highly parallelizable numerical method based on a perturbative series of the type considered in Refs. 2–3. Finally, we assess and validate the mathematical models and the numerical method proposed analyzing the numerical results obtained with a parallel implementation of the numerical method in several experiments on test problems. Impressive speedup factors are obtained executing the algorithms on a parallel machine when the number of processors used in the computation ranges between 1 and 100. Some virtual reality applications and some animations relative to the numerical experiments can be found in the website http://www.econ.unian.it/recchioni/w10/. 相似文献
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An improved hybrid method is introduced in this paper as a numerical method to reconstruct the scatterer by far-field pattern for just one incident direction with unknown physical properties of the scatterer. The improved hybrid method inherits the idea of the hybrid method by Kress and Serranho which is a combination of Newton and decomposition method, and it improves the hybrid method by introducing a general boundary condition. The numerical experiments show the feasibility of this method. 相似文献
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Juan Liu & Fuming Ma 《数学研究通讯:英文版》2011,27(3):215-226
An improved hybrid method is introduced in this paper as a numerical
method to reconstruct the scatterer by far-field pattern for just one incident direction
with unknown physical properties of the scatterer. The improved hybrid method inherits the idea of the hybrid method by Kress and Serranho which is a combination
of Newton and decomposition method, and it improves the hybrid method by introducing a general boundary condition. The numerical experiments show the feasibility
of this method. 相似文献
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This paper is concerned with the electromagnetic scattering by a nonperfectly conductor obstacle in chiral environment.A two-dimensional mathematical model is established.The existence and uniqueness o... 相似文献
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In this paper,we study the electromagnetic scattering from a two dimen- sional large rectangular open cavity embedded in an infinite ground plane,which is modelled by Helmholtz equations.By introducing nonlocal transparent boundary con- ditions,the problem in the open cavity is reduced to a bounded domain problem.A hypersingular integral operator and a weakly singular integral operator are involved in the TM and TE cases,respectively.A new second-order Toeplitz type approximation and a second-order finite difference scheme are proposed for approximating the hyper- singular integral operator on the aperture and the Helmholtz in the cavity,respectively. The existence and uniqueness of the numerical solution in the TE case are established for arbitrary wavenumbers.A fast algorithm for the second-order approximation is pro- posed for solving the cavity model with layered media.Numerical results show the second-order accuracy and efficiency of the fast algorithm.More important is that the algorithm is easy to implement as a preconditioner for cavity models with more general media. 相似文献
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Well-posedness of nonlocal boundary value problems is studied for some class of mixed-type equations which includes the Chaplygin equation and parabolic equations with varying time direction. 相似文献
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We are interested in approximating the solution of a first-order quasi-linear equation associated with a forced unilateral obstacle condition. With this view, we make use of the time-splitting method developed classically to compute discontinuous solutions of nonhomogeneous scalar conservation laws. Here, one proves that this fractional step method converges in L1 to the weak entropy solution of the considered obstacle problem. In the case of the Cauchy problem, an L1-error bound in
is established. 相似文献
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The object of this paper is to investigate the three-dimensional electro- magnetic scattering problems in a two-layered background medium. These problems have an important application in today's technology, such as to detect objects that are buried in soil. Here, we model both the exterior impedance problem and the inhomogeneous medium problem in R3. We establish uniqueness and existence for the solution of the two scattering problems, respectively. 相似文献