Numerical methods for determining the coefficients of elastic wave equation
Organizer
Speaker
Wensheng Zhang
Time
Thursday, December 12, 2024 2:30 PM - 3:30 PM
Venue
A7-201
Online
Zoom 435 529 7909
(BIMSA)
Abstract
Wave propagation based on elastic wave equation has wide applications in various scientific problems. In this talk, I will introduce the numerical methods for determining coefficients of elastic wave equation by the trust-region method. The elastic wave equation is solved by the staggered-grid finite-difference method in the time domain. The inverse problem is an optimization problem of minimizing the misfit between the observed data and simulated data. Usually the gradient-based search methods are applied to update the model parameters iteratively. Here we investigate the trust region method to invert the three media parameters, i.e., the density and two Lamé parameters, simultaneously. In order to solve the trust-region subproblem, the dogleg method and the two dimensional subspace method are adopted. In the trust region method, as long as the trust-region radius is well updated, the model updating can be performed for every iteration with the fixed trial step and there is no more extra computation for forward problem like the line search method. Numerical computations for the benchmark Marmousi model are given. The inversion results and comparisons show that the trust region method is efficient and behaves better than the line search method.
Speaker Intro
张文生，中国科学院数学与系统科学研究院，研究员，博士生导师，长期从事波动方程正反问题的数值计算与理论分析的研究工作，发表论文数十篇，专著两部。曾主持或作为主要成员完成了多个国家重大科研项目，包括两项国家重点基础研究发展计划项目、国家重点基金项目和国家自然基金面上项目。在波场参数成像与反演的研究中，解决了其中的重要科学问题，推动了相关领域的研究和发展。