关于一类广义Tikhonov 正则化方法的饱和效应分析

Tikhonov正则化方法是研究不适定问题最重要的正则化方法之一,但由于这种方法的饱和效应出现的太早,使得无法随着对解的光滑性假设的提高而提高正则逼近解的收敛率,也即对高的光滑性假设,正则解与准确解的误差估计不可能达到阶数最优.Schrroter T 和Tautenhahn U给出了一类广义Tikhonov正则化方法并重点讨论了它的最优误差估计, 但却未能对该方法的饱和效应进行研究.本文对此进行了仔细分析,并发现此方法可以防止饱和效应,而且数值试验结果表明此方法计算效果良好.     

非线性不适定问题的Tikhonov正则化的参数选取方法

在Ｔｉｋｈｏｎｏｖ正则化中，如何选取正则参数极为重要，直至现在，仍有许多问题期待解决．本文对非线性不适定问题考虑了Ｔｉｋｈｏｎｏｖ正则化，提出了一个新的简单的正则参数的最优选取法，并对由此得到的正则参数，研究了Ｔｉｋｈｏｎｏｖ正则化解的收敛性，并且当ｘ－最小范数解满足“源条件”时，在适当的条件下，导出了最优收敛率．     

一类非线性不适定问题的Tikhonov正则化

本文在B anach空间中,研究一类非线性不适定问题的正则化,所研究的算子是多值的,且是近拟的,假定原始问题是可解的,利用带双参数的T ikhonov正则化方法构造出逼近步骤.     

非线性不适定问题的正则化方法

本文考虑非线性不适定问题Tx=y的近似求解,利用Тихоноь正则化方法来逼近问题的x-极小模解,当算子和右端都近似已知时,给出一种决定正则化参数的方法,并给出正则解的收效性和渐近收敛阶估计。     

约束Fractional Tikhonov正则化的模迭代方法

反问题是现在数学物理研究中的一个热点问题,而反问题求解面临的一个本质性困难是不适定性。求解不适定问题的普遍方法是:用与原不适定问题相“邻近”的适定问题的解去逼近原问题的解,这种方法称为正则化方法.如何建立有效的正则化方法是反问题领域中不适定问题研究的重要内容.当前,最为流行的正则化方法有基于变分原理的Tikhonov正则化及其改进方法,此类方法是求解不适定问题的较为有效的方法,在各类反问题的研究中被广泛采用,并得到深入研究.     

Tikhonov 正则化的饱和性与逆结果及后验参数选取 *

对解非线性不适定问题的Tikhonov正则化证明了饱和性与一些逆结果 ,并考虑了正则化参数的最优后验选取 .     

应用正则化子建立求解不适定问题的正则化方法的探讨

根据紧算子的奇异系统理论,提出一种新的正则化子进而建立了一类新的求解不适定问题的正则化方法。分别通过正则参数的先验选取和后验确定方法,证明了正则解的收敛性并得到了其最优的渐近收敛阶;验证了应用Newton迭代法计算最佳参数的可行性。最后建立了当算子与右端均有扰动时相应的正则化求解策略。文中所述方法完善了一般优化正则化策略的构造理论。     

非线性不适定问题的双参数正则化

在Banach空间中, 研究一类非线性不适定问题的正则化. 所研究的算子是多值的, 且是近似的. 假定原始问题是可解的, 利用带双参数的Tikhonov正则化方法构造出强收敛的逼近步骤. 所得结论是前人结论的推广和延拓.     

MULTI-PARAMETER TIKHONOV REGULARIZATION FOR LINEAR ILL-POSED OPERATOR EQUATIONS

We consider solving linear ill-posed operator equations. Based on a multi-scale decomposition for the solution space, we propose a multi-parameter regularization for solving the equations. We establish weak and strong convergence theorems for the multi-parameter regularization solution. In particular, based on the eigenfunction decomposition, we develop a posteriori choice strategy for multi-parameters which gives a regularization solution with the optimal error bound. Several practical choices of multi-parameters are proposed. We also present numerical experiments to demonstrate the outperformance of the multiparameter regularization over the single parameter regularization.     

关于迭代Tikhonov正则化的最优正则参数选取

本文讨论了算子和右端都近似给定的第一类算子方程的迭代Ｔｉｋｈｏｎｏｖ正则化，给出了不依赖于准确解的任何信息但能得到最优收敛阶的正则参数选取法。     

用Tikhonov正则化方法求一阶和两阶的数值微分

Numerical differentiation is an ill-posed problem, which is important in scientific research and practical applications.In this paper, we use the Tikhonov regularization method to discuss the first and secord order derivatives of a smooth function. The error estimate is also given. And the numerical results prove that our method is applicable.     

A FAST CONVERGENT METHOD OF ITERATED REGULARIZATION

This article presents a fast convergent method of iterated regularization based on the idea of Landweber iterated regularization, and a method for a-posteriori choice by the Morozov discrepancy principle and the optimum asymptotic convergence order of the regularized solution is obtained. Numerical test shows that the method of iterated regularization can quicken the convergence speed and reduce the calculation burden efficiently.     

MULTILEVEL ITERATION METHODS FOR SOLVING LINEAR ILL-POSED PROBLEMS

In this paper we develop multilevel iteration methods for solving linear systems resulting from the Galerkin method and Tikhonov regularization for ill-posed problems, The algorithm and its convergence analysis ave presented in an abstract framework.     

非线性不适定问题一种双循环的牛顿型迭代格式

本文研究非线性算子方程F(x)=y的解,结合最速下降法,Newton-Landweber迭代格式及正则化思想,在F满足适当的条件下,构造出新的双循环迭代格式。本文对格式的收敛性进行了严格论证,并估计出迭代格式的收敛精度。     

A UNIFIED TREATMENT OF REGULARIZATION METHODS FOR LINEAR ILL-POSED PROBLEMS

1　ＩｎｔｒｏｄｕｃｔｉｏｎＬｅｔＡ :Ｘ→ＹｂｅａｂｏｕｎｄｅｄｌｉｎｅａｒｏｐｅｒａｔｏｒｂｅｔｗｅｅｎＨｉｌｂｅｒｔｓｐａｃｅｓＸａｎｄＹ ,ａｎｄｌｅｔＡ ｄｅ ｎｏｔｅｔｈｅＭｏｏｒｅ ＰｅｎｒｏｓｅｇｅｎｅｒａｌｉｚｅｄｉｎｖｅｒｓｅｏｆＡ (ｃｆ.[4 ]) .Ｔｈｉｓｐａｐｅｒｃｏｎｃｅｒｎｓｔｈｅｒｅｓｏｌｕｔｉｏｎｏｆｔｈｅｇｅｎｅｒａｌｉｚｅｄｓｏｌｕｔｉｏｎｘ :=Ａ ｙ0 ｏｆｔｈｅｅｑｕａｔｉｏｎＡｘ=ｙ0 (1.1)ｗｉｔｈｙ0 ∈Ｄ(Ａ ) :=Ｒ(Ａ) +Ｒ(Ａ) ⊥,ｗｈｅｒｅＤ(Ａ )ａｎｄＲ(Ａ)ｄｅｎｏｔ…     

REGULARIZATION OF AN ILL-POSED HYPERBOLIC PROBLEM AND THE UNIQUENESS OF THE SOLUTION BY A WAVELET GALERKIN METHOD

We consider the problem K(x)u xx = u tt , 0 < x < 1, t ≥ 0, with the boundary condition u(0,t) = g(t) ∈ L 2 (R) and u x (0, t ) = 0, where K(x) is continuous and 0 < α≤ K (x) < +∞. This is an ill-posed problem in the sense that, if the solution exists, it does not depend continuously on g. Considering the existence of a solution u(x, ) ∈ H 2 (R) and using a wavelet Galerkin method with Meyer multiresolution analysis, we regularize the ill-posedness of the problem. Furthermore we prove the uniqueness of the solution for this problem.