Qianshun Chang

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In this paper, we consider solutions of Toeplitz systems A n u = b where the Toeplitz matrices A n are generated by nonnegative functions with zeros. Since the matrices A n are ill-conditioned, the convergence factor of classical iterative methods, such as the damped Jacobi method, will approach 1 as the size n of the matrices becomes large. Here we propose(More)
In this paper, we construct a Lattice Boltzmann scheme to simulate the well known total variation based restoration model, that is, ROF model. The advantages of the Lattice Boltzmann method include the fast computational speed and the easily implemented fully parallel algorithm. A conservative property of the LB method is discussed. The macroscopic PDE(More)
For a given blur, we apply a fixed point method to solve the total variation-based image restoration problem. A new algorithm for the discretized system is presented. Convergence of outer iteration is efficiently improved by adding a linear term on both sides of the system of nonlinear equations. In inner iteration, an algebraic multigrid (AMG) method is(More)
Based on the approach suggested by Tarantola, and Gauthier et al., we show that the alternate use of the step (linear) function basis and the block function (quasi-delta function) basis can give accurate full waveform inversion results for the layered acoustic systems, starting from a uniform background. Our method is robust against additive white noise (up(More)