Determination of the initial data in a time-fractional diffusion-wave problem by a final time data

This paper is to determine an initial value for a time-fractional diffusion-wave equation from the final time data. The regularity of the weak solution for the direct problem is improved. The existence and uniqueness of a weak solution for the adjoint problem are proved by using the Fourier method. The Tikhonov regularization method is applied for finding a stable approximate solution. In order to get the minimizer of the Tikhonov regularization functional, we propose a conjugate gradient algorithm based on the strict deductions of the sensitive problem and the adjoint problem. Four numerical examples in one-dimensional and two-dimensional cases are provided to show the effectiveness and stability of the proposed algorithm. (C) 2019 Elsevier Ltd. All rights reserved.