We propose elastic isotropic wavefield tomography formulated with the misfit of observed and recorded data as the objective function. The adjoint-state method enables efficient calculation of the gradient of this data misfit function. We solve this optimization problem with the gradient-descent method in order to update the model parameters iteratively. Using the elastic isotropic wave-equation...

Abstract We study a PDE-constrained optimal control problem that involves functions of bounded variation as controls and includes the TV seminorm in objective. apply path-following inexact Newton method to problems arise from smoothing adding an $$H^1$$ H 1 regularizati...

This paper discusses the computation of derivatives for optimization problems governed by linear hyperbolic systems of partial differential equations (PDEs) that are discretized by the discontinuousGalerkin (dG)method.An efficient and accurate computation of these derivatives is important, for instance, in inverse problems and optimal control problems. This computation is usually based on an ad...

An optimal estimation method for state and distributed parameters in 1-D hyperbolic system based on adjoint method is proposed in this paper. A general form of the partial differential equations governing the dynamics of system is first introduced. In this equation, the initial condition or state variable as well as some empirical parameters are supposed to be unknown and need to be estimated. ...

We propose an image-domain velocity model building method using the two-way wave equation and extended seismic images. We show that common-image-point gathers can effectively extract velocity information from steep reflections imaged with the two-way wave propagator. Such gathers have the advantages over conventional common-image gathers that they are capable of characterizing reflections with ...

This note is a first attempt to perform waveform inversion by utilizing recent developments in semidefinite relaxations for polynomial equations to mitigate non-convexity. The approach consists in reformulating the inverse problem as a set of constraints on a low-rank moment matrix in a higher-dimensional space. While this idea has mostly been a theoretical curiosity so far, the novelty of this...

The spherical harmonics (PN) method is widely used in solving the neutron transport equation, but it has some disadvantages. One of them omes from the complexity of the PN equations. Another one comes from the difficulty of dealing with the vacuum boundary condition exactly. In his paper, the PN method is applied to the self-adjoint angular flux (SAAF) neutron transport equation and a set of PN...

Using the Modified Picard Method of Parker and Sochacki [1, 2], we derive a hybrid scheme using the analytical Picard method with approximations to the differential operators. This new method, called Discretized Picard’s Method, uses approximations in the space dimensions to compute derivatives but utilizes a continuous approximation in the time dimension. We illustrate the method using finite ...

application of backward probability method in pollutant source tracking in non-uniform flow riversalireza ghanem.sc. student of water structures, tarbiat modares university, tehranmehdi mazaheri assistant prof., department of water structures, tarbiat modares university, tehranjamal mohammad vali samaniprofessor, department of water structures, tarbiat modares university, tehranintroductionriv...