An improved iteration regularization method and application to reconstruction of dynamic loads on a plate

We present an improved iteration regularization method for solving linear inverse problems. The algorithm considered here is detailedly given and proved that the computational costs for the proposed method are nearly the same as the Landweber iteration method, yet the number of iteration steps by the present method is even less. Meanwhile, we obtain the optimum asymptotic convergence order of the regularized solution by choosing a posterior regularization parameter based on Morozov’s discrepancy principle, and the present method is applied to the identification of the multi-source dynamic loads on a surface of the plate. Numerical simulations of two examples demonstrate the effectiveness and robustness of the present method.     

A numerical method of structure-preserving model updating problem and its perturbation theory

A method is presented to update a special finite element (FE) analytical model, based on matrix approximation theory with spectral constraint. At first, the model updating problem is treated as a matrix approximation problem dependent on the spectrum data from vibration test and modal parameter identification. The optimal approximation is the first modified solution of FE model. An algorithm is given to preserve the sparsity of the model by multiple correction. The convergence of the algorithm is investigated and perturbation of the modified solution is analyzed. Finally, a numerical example is provided to confirm the convergence of the algorithm and perturbation theory.     

关于强增生算子的带误差项的Ishikawa和Mann迭代程序的注记

设Ｘ是实Ｂａｎａｃｈ空间,Ｈ：Ｘ→Ｘ是Ｌｉｐｓｃｈｉｔｚ算子,Ｔ：Ｘ→Ｘ是值域有界且一致连续的算子,Ｈ＋Ｔ是强增生算子,则具有误差项的Ｉｓｈｉｋａｗａ和Ｍａｎｎ迭代序列强收敛到方程Ｈｘ＋Ｔｘ＝ｆ的唯一解,这些结论推广了最新文献中的相应结果。     

Geometrically nilpotent subvarieties

We construct some examples of polynomial maps over finite fields that admit subvarieties with a peculiar property: every geometric point is mapped to a fixed point by some iteration of the map, while the whole subvariety is not. Several related open questions are stated and discussed.