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1.
预条件共轭梯度法在辐射和散射问题中的应用   总被引:3,自引:1,他引:2  
用矩量法求解一些辐射和散射问题 ,如线天线辐射和线状体散射等问题时 ,可以产生一个 Toeplitz线性方程组 ,采用预条件共轭梯度法 (PCG)与快速富里叶变换 (FFT)的结合方法 (PCGFFT)来求解该方程组 ,其中预条件器采用 T.Chan的优化循环预条件器。使用 PCGFFT算法 ,可有效地节省内存 ,提高了计算速度。为说明其有效性 ,将 PCGFFT算法与 CGFFT算法以及 Levinson递推算法进行了对比。  相似文献   

2.
班永灵  聂在平  于哲峰 《电子学报》2007,35(9):1739-1744
基于六面体的高阶叠层基函数,提出了一种新颖的构造预条件矩阵的方法.该方法基于叠层基函数特有的嵌套性质,利用特殊的编号策略,将由有限元方法导致的系数矩阵分成块矩阵的形式,最后由不完全LU分解(ILU)导出近似的预条件矩阵.结合该预条件技术,发展了一种叠层预条件-GMRES算法,并将该预条件算法用于加速三维腔体散射的矢量有限元/边界积分(FE-BI)矩阵方程的迭代求解,讨论了该预条件算法中块矩阵ILU分解截断门限Tdr对算法的影响.  相似文献   

3.
袁浩波  杨蒙  党晓杰  王楠 《电子学报》2017,45(10):2549-2554
计算电磁学中矩量法产生的系统矩阵是病态矩阵,使用迭代方法求解时很难收敛,即使采用现有的预条件技术也经常不收敛.本文借用不适定问题求解中的正则化方法的概念,提出采用正则化矩阵作为矩量法中矩阵方程的一个预条件矩阵.这种预条件方法可以直接改善原矩阵的特征值分布,而且不需要额外的空间来存储预条件矩阵.此外,本文提出通过正则化矩阵方程的L曲线的二阶导数的最大值点来确定正则化参数,使得预条件矩阵方程求解的效率最高.数值实验表明,对于高阶矩量法求解电场积分方程或者磁场积分方程时分别产生的矩阵方程,采用常见的预条件迭代方法求解时收敛很慢,但是采用本文的预条件迭代方法却可以较快地收敛.  相似文献   

4.
王文博  徐金平 《电子学报》2010,38(9):2009-2013
 本文针对体积分方程矩量法(VIE-MoM)分析三维非均匀介质电磁散射问题所导出的大型矩阵方程的求解问题, 基于多层快速极子技术(MLFMA)算法研究了快速近似迭代方法.提出了一种基于MLFMA分组方案对系数矩阵进行重组并提取强耦合元素的近场预条件器的构造方法,有效地提高了广义最小余量法(GMRES)的迭代收敛速度.提出了一种在迭代计算过程中的近似矩阵向量乘积方案,明显降低了单步计算过程中MLFMA远区耦合作用的计算时间.计算实例表明,采用本文的迭代加速技术可使计算速度提高3至5倍,有效地提高了VIE-MoM大型矩阵方程的迭代求解速度.  相似文献   

5.
周后型  洪伟  童创明 《电子学报》2001,29(12):1601-1604
本文提出三重Toeplitz线性方程组预条件共轭梯度法,并将该法与快速付里叶变换(FFT)结合.这种结合算法称为PCGFFT.将PCGFFT应用于振子阵列天线的RCS分析中.由于预条件器的使用,系数矩阵的条件数得到了很大改善.数值结果表明,PCGFFT不仅降低了对计算机内存的需求,加快了迭代速度而且提高了算法的收敛性.  相似文献   

6.
张玉  梁昌洪 《电子学报》2005,33(9):1623-1625
针对矩量法分析大型波导缝隙阵时矩阵填充和方程求解速度慢的问题,本文首先给出了负载均衡的并行计算方案,解决了阻抗矩阵填充非常慢这一困难,接着提出了一种新的 —"缝隙邻居"预条件方法,因其具有从物理上将基函数之间的近场作用充分考虑到预条件矩阵中的优点,故可将典型共轭梯度法求解矩量法分析缝隙阵所得矩阵方程的收敛速度提高了约一个数量级,从而实现了大型缝隙阵列的快速仿真.数值实例表明本文方法的高效性和准确性.  相似文献   

7.
一种基于Doolittle LU分解的线性方程组并行求解方法   总被引:1,自引:0,他引:1  
矩阵方程的快速求解是矩量法计算电大问题的关键,LU分解是求解线性方程组的有效方法.该文详细地分析了Doolittle LU分解过程,基于分解过程的特点,在MPI(Message-Passing interface) 并行环境下,提出了按直角式循环对进程进行任务分配的并行求解方法.实验证明该方法可以有效地减少进程间数据通信量,从而加快计算速度.  相似文献   

8.
李月卉    聂在平  孙向阳  张向前 《半导体光电》2013,34(1):34-37,41
提出了一种新型RIC预条件COCG迭代技术,用于改善有限元法仿真分析光电工程问题所产生的高度非正定的线性系统的迭代求解.提出的RIC预条件子是针对基本IC算法可能出现的分解崩溃问题,通过对主元进行加强来获得稳定的分解过程,进而产生高效的预条件子.数值试验表明,提出的RIC预条件子不仅能有效避免COCG迭代等方性崩溃,而且比常用的预条件子更高效;此外,RIC对其他若干Krylov子空间迭代法求解性能的改善作用也相当明显.  相似文献   

9.
景杨  余超  陈艳  匡恒 《信息通信》2014,(6):31-32
首先介绍求解稀疏线性方程组的选主元LU分解法、SOR法和共轭梯度法,然后分析不同阶的线性方程组用三种方法求解时的误差、运算时间、迭代次数等参数。最终得出:在运算小型稀疏矩阵时采用选主元LU分解法,当阶数较大时选取共轭梯度法将更为妥当。  相似文献   

10.
频域高阶矩量法越来越多地用于求解目标散射问题.但高阶矩量法得到的矩阵方程中,系数矩阵条件数较差,并且一般为非对角占优阵,通常用计算效率较低的直接方法求解.本文针对叠层高阶基函数的特点,提出了一种函数空间域分解的加性Schwarz预处理技术.通过数值计算,给出了最优分解方案,并数值验证了预处理技术的有效性.  相似文献   

11.
FAFFA加速的PO-MM研究复杂金属载体上线天线电磁特性   总被引:3,自引:0,他引:3       下载免费PDF全文
华夷和  徐金平  牛臻弋 《电子学报》2003,31(Z1):2045-2049
本文提出了一种快速远场近似(FAFFA)加速的混合物理光学矩量法(POMM),利用FAFFA加速计算矩阵方程中的矩阵矢量积,明显提高了计算效率.对物体表面上的远场组之间的耦合作用推导出了一组简洁的计算公式,并分析了计算复杂度.复杂金属组合体上线天线输入导纳、互导纳和方向性图的计算结果与文献结果一致.利用该方法分析计算了一个舰船模型上线天线的电磁特性.数值结果表明了这种方法的正确性和工程应用中的有效性.  相似文献   

12.
An iterative solution of linear systems is studied,which arises from the discretization of a wire antennas attached with dielectric objects by the hybrid finite-element method and the method of moment (hybrid FEM-MoM).It is efficient to model such electromagnetic problems by hybrid FEM-MoM,since it takes both the advantages of FEM's and MoM's ability.But the resulted linear systems are complicated,and it is hard to be solved by Krylov subspace methods alone,so a two-level preconditioning technique will be studied and applied to accelerate the convergence rate of the Krylov subspace methods.Numerical results show the effectiveness of the proposed two-level preconditioning technique.  相似文献   

13.
The Incomplete Cholesky factorizations preconditioning scheme is applied to the conjugate gradient (CG) method for solving a large system of linear equations resulting from finite element method (FEM) analysis of millimeter wave filters. As is well known, the convergence of CG method deteriorates with increasing EM wave number and in millimeter wave band the eigen-values of A are more and more scattered between both the right and the left half-plane. The efficient implementation of this preconditioned CG (PCG) algorithm is described in details for Complex coefficient matrix. With incomplete factorization preconditioning scheme in the conjugate gradient algorithm, this PCG approach can reach convergence in 20 times CPU time shorter than CG for several typical millimeter wave structures.  相似文献   

14.
Application of on-surface MEI method on wire antennas   总被引:1,自引:0,他引:1  
The formulas of the on-surface measured equation of invariance (OSMEI) for wire antennas are derived. The unknowns of each node on the antenna surface are expressed by the vector potential function and surface current density. The unknowns in the vicinity of each node are coupled in a linear equation and the coefficients of the linear equation are determined by the measured equation of invariance (MEI) method. The final impedance matrix obtained by the OSMEI is a highly sparse matrix. It demonstrates that the currents on thin wire antennas may also be solved by a differential equation-based formulation in addition to the conventional integral equations  相似文献   

15.
The symmetric successive overrelaxation (SSOR) preconditioning scheme is applied to the conjugate-gradient (CG) method for solving a large system of linear equations resulting from the use of edge-based finite-element method (FEM). For this scheme, there is no additional computing time required to construct the preconditioning matrix and it contains more global information of the coefficient matrix when compared with those of the banded-matrix preconditioning scheme. The efficient implementation of this preconditioned CG (PCG) algorithm is described in details for complex coefficient matrix. With SSOR as the preconditioner and its efficient implementation in the CG algorithm, this PCG approach can reach convergence in five times CPU time shorter than CG for several typical structures. By comparison with other preconditioned techniques, these results demonstrate that SSOR preconditioning strategy is especially effective for CG iterative method when an edge FEM is applied to solve large-scale time-harmonic electromagnetic-field problems  相似文献   

16.
The method of conjugate gradients is applied to the analysis of radiation from thin-wire antennas. With this iterative technique, it is possible to solve electrically large arbitrarily oriented wire structures without storing any matrices as is conventionally done in the method of moments. The basic difference between the proposed method and Galerkin's method, for the same expansion functions, is that for the iterative technique we are solving a least squares problem. Hence, as the order of the approximation is increased, the proposed technique guarantees a monotonic decrease of the least squared error (parallel AI - Yparallel^{2}), whereas Galerkin's method does not. Even though the method converges for any initial guess, a good one may significantly reduce the time of computation. Also, explicit error formulas are given for the rate of convergence of this method. Hence, any problem can be solved to a prespecified degree of accuracy. It is shown that the method has the advantage of a direct solution as the final solution is obtained in a finite number of steps. The method is also suitable for solving singular operator equations in which case the method monotonically converges to the least squares solution with minimum norm. Numerical results are presented for the thin-wire antennas and are compared with the solution obtained by the method of moments.  相似文献   

17.
Matrix methods for field problems   总被引:9,自引:0,他引:9  
A unified treatment of matrix methods useful for field problems is given. The basic mathematical concept is the method of moments, by which the functional equations of field theory are reduced to matrix equations. Several examples of engineering interest are included to illustrate the procedure. The problem of radiation and scattering by wire objects of arbitrary shape is treated in detail, and illustrative computations are given for linear wires. The wire object is represented by an admittance matrix, and excitation of the object by a voltage matrix. The current on the wire object is given by the product of the admittance matrix with the voltage matrix. Computation of a field quantity corresponds to multiplication of the current matrix by a measurement matrix. These concepts can be generalized to apply to objects of arbitrary geometry and arbitrary material.  相似文献   

18.
This paper presents an integral equation that can handle wire antennas on a semi-infinite dielectric material. The integral equation is reduced to a set of linear equations by the method of moments. For efficiency, the impedance matrix element Zm,n is divided into two parts on the basis of weighted Green's function extractions. The far-zone radiation field, which is formulated using the stationary phase method, is also described. After the validity of the presented numerical techniques is checked using a bow-tie antenna, a spiral antenna is analyzed. The current distribution, radiation pattern, axial ratio, power gain, and input impedance are discussed. It is found that the radiation field inside a dielectric material is circularly polarized. As the relative permittivity of the dielectric material increases, the angle coverage over which the axial ratio is less than 3 dB becomes narrower  相似文献   

19.
Generalization of the matrix inversion lemma   总被引:1,自引:0,他引:1  
A generalized form of the matrix inversion lemma is shown which allows particular forms of this lemma to be derived simply. The relationships between this direct method for solving linear matrix equations, lower-diagonal-upper decomposition, and iterative methods such as point-Jacobi and Hotelling's method are established. The generalized form is used to derive a new factorization scheme and a new matrix inversion algorithm with a high degree of parallelism.  相似文献   

20.
A review of the finite-difference time-domain (FDTD) method is presented and then employed to model and predict the radiation patterns of three basic configurations of mobile antennas. The directive gain and the input impedance are also calculated. The antennas' configurations considered are a quarter-wavelength monopole mounted on a conducting box, a bent-slot half-wavelength dipole flush mounted on a conducting box, and a quarter-wavelength monopole mounted on the top of an automobile. Three-feed models are discussed and the contour integral is used to model the wire antenna. Transformation of the near field data, resulting from the FDTD, to obtain the radiation patterns is discussed based on the equivalence principle. The radiation patterns obtained using the FDTD compare well with published results  相似文献   

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