一个逆奇异值问题

１引言是Ｃｈｕ,Ｍ．Ｔ［２］．首先提出逆奇异值问题,他（那时就）认为［２］,尽管还没看到这样的问题在物理等方面的应用,但这个问题本身是有意义的．在文［６］中,ＲａｍＹ．Ｍ．和Ｅｌｈａｙ,Ｓ．就提出了一个具有物理背景的逆奇异值问题．本文考虑的问题如下：问题Ｐ　找（如果存在的话）一个ｎ阶的单位下三角阵,使它有预先给定的正数１,２,…,ｎ作为它的奇异值．这个问题与Ｒａｍ和Ｅｌｈａｙ提出的问题［６］相近,但显然要简单得多．在下一节我们将讨论问题Ｐ的可解性和解存在的充分必要条件,第三节给出求解问题Ｐ的算法…     

THE SOLVABILITY CONDITIONS FOR AN INVERSE EIGEN-PAIR PROBLEM

This paper discusses problem IEP:Given n×m matrix X and m×m diagonal matrix A, find an n×n matrix A such that AX=XA.The new solvablily conditions for the problem IEP are obtained. The eigenvalue dislribulaion of the solutions for the problem IEP are described in detail.     

SOLUTION OF BACKWARD HEAT PROBLEM BY MOROZOV DISCREPANCY PRINCIPLE AND CONDITIONAL STABILITY

Consider a 1-D backward heat conduction problem with Robin boundary condition. We recover u(x, 0) and u(x, t0) for to ∈(0, T) from the measured data u(x, T) respectively. The first problem is solved by the Morozov discrepancy principle for which a 3-order iteration procedure is applied to determine the regularizing parameter. For the second one, we combine the conditional stability with the Tikhonov regularization together to construct the regularizing solution for which the convergence rate is also established. Numerical results are given to show the validity of our inversion method     

AN ITERATIVE BEM FOR THE INVERSE PROBLEM OF DETECTING CORROSION IN A PIPE

In this paper, we consider an inverse problem of determining the corrosion occurring in an inaccessible interior part of a pipe from the measurements on the outer boundary. The problem is modelled by Laplace's equation with an unknowm term γ in the boundary condition on the inner boundary. Based on the Maz'ya iterative algorithm, a regularized BEM method is proposed for obtaining approximate solutions for this inverse problem. The numerical results show that our method can be easily realized and is quite effective.     

子空间上的一类矩阵反问题

1 引言 设Rn×m为所有n×m实矩阵的集合,ASRn×n为n阶实反对称矩阵的集合,ORn×n 为n阶实正交矩阵的全体. In是n阶单位矩阵,A+,R(A),N(A)分别表示矩阵A的 Moore-Penrose广义逆、值域及零空间,并记EA=I-AA+,FA=I-A+A(I为单位矩 阵,A为任意矩阵).对A=(aij),B=(bij)∈Rn×m,A*B=(aijbij)表示矩阵A与B 的Hadamard积.在Rn×m上定义矩阵A与B的内积为(A,B)=tr(BT A),则由此内积 导出的范数‖A‖=(A,A)~(1/2)是矩阵的Frobenius范数,并且Rn×m构成一个完备的内积 空间.     

振动杆有限差分模型的一类特征值反问题

1引言杆是重要的工程构件之一,具有分布质量的杆的纵向振动由下面的偏微分方程描述:     

AN INVERSE EIGENVALUE PROBLEM FOR JACOBI MATRICES

Let T1,n be an n x n unreduced symmetric tridiagonal matrix with eigenvaluesand is an (n - 1) x (n - 1) submatrix by deleting the kth row and kth column, k = 1, 2,be the eigenvalues of T1,k andbe the eigenvalues of Tk+1,nA new inverse eigenvalues problem has put forward as follows: How do we construct anunreduced symmetric tridiagonal matrix T1,n, if we only know the spectral data: theeigenvalues of T1,n, the eigenvalues of Ti,k-1 and the eigenvalues of Tk+1,n?Namely if we only know the data: A1, A2, An,how do we find the matrix T1,n? A necessary and sufficient condition and an algorithm ofsolving such problem, are given in this paper.     

AN INVERSE EIGENVALUE PROBLEM FOR JACOBI MATRICES

In this paper, we discuss an inverse eigenvalue problem for constructing a 2n × 2n Jacobi matrix T such that its 2n eigenvalues are given distinct real values and its leading principal submatrix of order n is a given Jacobi matrix. A new sufficient and necessary condition for the solvability of the above problem is given in this paper. Furthermore, we present a new algorithm and give some numerical results.     

一类Jacobi矩阵广义特征值反问题

称为n阶Jacobi矩阵,振动反问题讨论由特征值（频率）和特征向量（模态）数据确定振动系统的物理参数,其研究对结构设计和结构物理参数识别具有重要意义,弹簧-质点系统的振动反问题归结为Jacobi矩阵的特征值反问题,这类问题已被许多学者研究[1-3]．     

一类Jacobi矩阵的逆特征问题

1 引 言n阶实对称矩阵J=若bi>0(i=1,2,…,n-1),称J为Jacobi矩阵,全体记为Jn. Jacobi矩阵的逆特征问题有广泛的应用.文[1]给出了由三个特征对构造相应的Jaco-bi矩阵的逆特征问题有唯一解的条件,但没有考虑到特征对的顺序,也没有给出有解的条件.本文从振动工程的实际出发,提出如下两个问题:     

反中心对称矩阵的广义特征值反问题

Given matrix X and diagonal matrix A , the anti-centrosymmetric solutions (A, B) and its optimal approximation of inverse generalized eigenvalue problem AX = BXA have been considered. The general form of such solutions is given and the expression of the optimal approximation solution to a given matrix is derived. The algorithm and one numerical example for solving optimal approximation solution are included.     

一维半线性双曲型方程未知源的反问题

We concern the inverse problem of determination of unknown source term for one-dimensional hyperbolic half-linear equation. Approach form for inverse problem is given by using correlative problem of assistant. We concern more ordinary problem than this paper, which is turned into integral equation with the method of characteristic line. We prove the existence and uniqueness of part solution for inverse problem, and unknown source can be solved bv successive approximation.     

代数特征值反问题Hermite情形可解的充分条件

１　引言及主要结果 本论文将要讨论如下问题［２,４］： 问题ＨＧ给定ｎ＋１个Ｈｅｒｍｉｔｅ矩阵Ａ＝（ａｉｊ）ｎ×ｎ和Ａｋ＝Ｓ和ｎ个实数　,求个实数ｃ１,…,ｃｎ,使得Ａ（ｃ）＝ ．的特征值为 对于上述问题,有解的充分条件已有许多研究结果,如［２,４,６］．下面将利用Ｂｒｏｕｗｅｒ不动点定理给出新的充分条件． 本文的符号和定义如下： 对任意ｎ阶Ｈｅｒｍｉｔｅ矩阵Ｂ＝（ｂｉｊ）,记Ｂ（０）＝Ｂ－ｄｉａｇ（ｂ１１,ｂ２２,…,ｂｎｎ）,ρ（Ｂ）表示Ｂ的谱半径, ｛λ（Ｂ）｝表示Ｂ的特征值（谱）集合,且设　表…     

子空间上亚半正定矩阵反问题解存在的条件

1 引 言 本文用R~(m×n)表示全体m×n阶实矩阵的集合,R~n为所有n维列向量的全体,OR~(n×n)为n阶正交矩阵的集合,I_n为n阶单位矩阵,A~T,A~ ,B(A),R(A)~⊥,N(A)分别表示矩阵A的转置,Moore-Penrose广义逆,值域,值域的正交补空间及零空间,Ps是     

偏微分方程边值反问题的数值方法研究

本文研究了奇异积分方程在反边值问题中的应用问题.利用圆周上的自然积分方程及其反演公式,把Laplace方程的边值反问题转化为一对超奇异积分方程和弱奇异积分方程的组合,通过选取三角插值近似奇异积分的计算并构造相应的配置格式,并使用Tikhonov正则化方法求解所得到的线性方程组.数值实验表明了该方法的有效性.     

A STABILITY ANALYSIS OF THE （k） JACOBI MATRIX INVERSE EIGENVALUE PROBLEM

In this paper we will analyze the perturbation quality for a new algorithm of the (k) Jacobi matrix inverse eigenvalue problem.     

离散形式的声阻抗反演问题的稳定性分析

1．引言考虑一维声波方程组从脉冲响应州附ω（0.t）反演声阻抗ε（x）,是一个适定问题（[1],[2],[3]）．声阻抗ε（X）具有明确的物理意义,它大于民与之对应的脉冲响应自然也应具有某种特殊的性质,本文对此进行深入的分析．本文首先引入KennethP．Bube和RobertBurrdge关于离散形式的声阻抗反演问题的一些基本结果,分析其实物理系统的脉冲响应的特征,说明了真实物理系统的脉冲响应具有某种正定性,这种特征是本质性的,由真实物理系统的内部固有性质所决定．在实际计算中,作为观测数据给出的脉冲响应数据如果具有这种特征,则反…     

A VARIATIONAL EXPECTATION-MAXIMIZATION METHOD FOR THE INVERSE BLACK BODY RADIATION PROBLEM

The inverse black body radiation problem, which is to reconstruct the area temperature distribution from the measurement of power spectrum distribution, is a well-known ill-posed problem. In this paper, a variational expectation-maximization （EM） method is developed and its convergence is studied. Numerical experiments demonstrate that the variational EM method is more efficient and accurate than the traditional methods, including the Tikhonov regularization method, the Landweber method and the conjugate gradient method.     

一类抛物型方程系数反问题的分裂算法

考虑利用终端时刻的温度u(x,T)=Z_T(x)反演热传导方程u_t-a~2u_(xx) q(x)u=0,x∈(0,1)中的未知系数q(x)的反问题.通过引进变换v(x,t)=(u_t(x,t)/u(x,t))将此非线性不适定问题的求解分解为两步.首先利用输入数据迭代求解一个非线性的正问题(该过程独立于未知系数),得到其迭代解v~(k)(x,t).其次利用q(x)与v(x,t)的关系式求出q(x)的近似解.对提出的反演方法,证明了采用的变换的可行性,得到了原反问题与由变换后的非线性正问题反演q(x)的等价性并且证明了迭代解的收敛性,给出了收敛速度.数值结果表明了该方法的有效性.