共查询到19条相似文献,搜索用时 62 毫秒
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针对双曲型方程定解问题{utt=a2uxx+f(t),0xπ,a∈R且a≠0,u(0,t)=v1(t),u(π,t)=v2(t),t0,u(x,0)=g(x),ut(x,0)=h(x),0≤x≤π研究了可以唯一决定未知函数组{v1(t),v2(t),f(t)}的基本条件,提出了该定解问题的反问题,并且讨论了此反问题的存在性与唯一性. 相似文献
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代数特征值反问题可解的充分条件 总被引:4,自引:1,他引:3
本文讨论如下代数特征值反问题的可解性:问题G.设A=(a_(ij))和A_k=(a_(ij)~((k)))(k=1,…,n)是一组n+1个n×n实矩 相似文献
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关于代数特征值反问题对称情况可解的充分条件 总被引:2,自引:1,他引:1
§1.引言 本文讨论下述特征值反问题的可解性: 问题 G.设A_0=(a_(ij)~((0)))和A_k=(a_(ij)~((k)))(k=1,…,n)是一组n+1个n×n实对称矩阵,λ_1,…,λ_n是n个不同的实数.求实数c_1,…,c_n使得矩阵A_0+sum from k-1 to n C_k·A_k的特征值为λ_1,…,λ_n. [1]和[2]曾给出此问题可解的充分条件.本文应用Rothe不动点定理[3]给出问题G可解的另外两个充分条件.本文的结果可判定[1]和[2]中定理所不能判定的某些问题 相似文献
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热传导反问题中非线性热源的存在性 总被引:2,自引:0,他引:2
研究热传导方程在一类非局部时间的边界条件下线性热源的反演问题。文中应用Sobolev紧性方法证明了热源在Hoelder空间中的(关于时间的)局部存在性。 相似文献
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本文讨论了椭圆型方程发((?)~2u)/((?)y~2) (?)/((?)x)(a(x)((?)u)/((?)x))=0在区域x>0,y>0上确定未知系数a(x)的反问题,文中给出了局部解的存在性、唯一性。 相似文献
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We consider the inverse problem to determine the shape of a open cavity embedded in the infinite ground plane from knowledge of the far-field pattern of the scattering of TM polarization.For its approximate solution we propose a regularized Newton iteration scheme.For a foundation of Newton type methods we establish the Fréchet differentiability of solution to the scattering problem with respect to the boundary of the cavity.Some numerical examples of the feasibility of the method are presented. 相似文献
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We consider the inverse problem to determine the shape of a open cavity embedded in the infinite ground plane from knowledge of the far-field pattern of the scattering of TM polarization.For its approximate solution we propose a regularized Newton iteration scheme.For a foundation of Newton type methods we establish the Fréchet differentiability of solution to the scattering problem with respect to the boundary of the cavity.Some numerical examples of the feasibility of the method are presented. 相似文献
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The inverse problem considered in this paper is to determine the
shape and the impedance of crack from a knowledge of the
time-harmonic incident field and the corresponding far field pattern
of the scattered waves in two-dimension. The combined single- and
double-layer potential is used to approach the scattered waves. As
an important feature, this method does not require the solution of $u$ and $\partial u / \partial \nu$ at each iteration. An
approximate method is presented and the convergence of this method
is proven. Numerical examples are given to show that this method is
both accurate and simple to use. 相似文献
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Uniqueness theorems are obtained for the problem of determiningthe shape of a sound-soft or sound-hard obstacle from a knowledgeof (1) the far-field pattern at a fixed value of the wave numberand a finite number of distinct incident fields, or (2) thetotal scattering cross section for an interval of wave numbersand the incident field propagating in an arbitrary direction. 相似文献
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We consider inverse potential scattering problems where the source of the incident waves is located on a smooth closed surface outside of the inhomogeneity of the media. The scattered waves are measured on the same surface at a fixed value of the energy. We show that these data determine the bounded potential uniquely. 相似文献
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Michael V. Klibanov 《Applicable analysis》2013,92(6):1135-1149
Uniqueness is proven for two non-overdetermined 3-d inverse problems of the determination of the spatially distributed sound speed in the frequency dependent acoustic PDE. The main new point is the assumption that only the modulus of the scattered complex valued wave field is measured on a certain set. The phase is unknown. 相似文献
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We give an example of an inverse problem for a hyperbolic equation which has a unique local solution but no global solutions. 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