Overdetermined systems of first kind integral equations appear in many applications. When the right-hand side is discretized, the resulting finite-data problem is ill-posed and admits infinitely many solutions. We propose a numerical method to compute the minimal-norm solution in the presence of boundary constraints. The algorithm stems from the Riesz representation theorem and operates in a reproducing kernel Hilbert space. Since the resulting linear system is strongly ill-conditioned, we construct a regularization method depending on a discrete parameter. It is based on the expansion of the minimal-norm solution in terms of the singular functions of the integral operator defining the problem. Two estimation techniques are tested for the automatic determination of the regularization parameter, namely, the discrepancy principle and the L-curve method. Numerical results concerning two artificial test problems demonstrate the excellent performance of the proposed method. Finally, a particular model typical of geophysical applications, which reproduces the readings of a frequency domain electromagnetic induction device, is investigated. The results show that the new method is extremely effective when the sought solution is smooth, but gives significant information on the solution even for non-smooth solutions.
Linear Lavrent'ev Integral Equation for the Numerical Solution of a Nonlinear Coefficient Inverse Problem
本文首次对M. M. Lavrent'ev在1964年提出了一个三维波动方程的系数反问题。数据不是超定的。收敛性分析以及数值结果。Lavrent'ev方程的一个有趣的特点是,在不进行任何线性化的情况下,它将一个高度非线性系数的反问题归结为一个第一类线性积分方程。然而,该方程的数值结果,其中使用的系数反问题产生的数据,显示出良好的重建精度。这与1951年导出的经典Gelfand-Levitan方程相似,该方程在一维情况下是有效的。
Boundary integral equation methods for the elastic and thermoelastic waves in three dimensions
School of Mathematical Sciences, Zhejiang University(浙江大学数学系);School of Mathematical Sciences, University of Electronic Science and Technology of China(电子科技大学数学系);Department of Computing and Mathematical Sciences, California Institute of Technology(加州理工学院计算与数学科学系)
Stability estimates of Nyström discretizations of Helmholtz decomposition boundary integral equation formulations for the solution of Navier scattering problems in two dimensions with Dirichlet boundary conditions