求一阶数值微分的L-广义解方法cTSVD

<正>1引言数值微分也就是给定一个函数在一个区间或某些离散点上的扰动数据来求函数的导数,它产生于很多实际问题当中,比如,图象处理中的边界识别问题;Abel积分方程的求解问题;化学中波谱的波峰识别问题.以及一些数学物理反问题当中.数值微     

线性算子方程广义解的存在性

本文中我们研究并得到了线性算子方程的Moore-Penrose广义解的稳定性性质。     

解不适定算子方程的一个定常二步隐式迭代法

１．引言 设Ｘ,Ｙ是两个Ｈｉｌｂｅｒｔ空间,Ａ：Ｘ→Ｙ是有界线性算子,考虑算子方程 Ａｘ＝ｙ（１．１）如果Ａ的值域Ｒ（Ａ）在Ｙ中非闭,则方程（１．１）是不适定的［１］．许多应用科学中都归结出这一类方程,特别地,许多反问题是不适定的［２,３］．本文考虑方程（１．１）的 Ｍｏｏｒｅ－Ｐｅｎｒｏｓｅ广义解,这里Ａ是算子Ａ的Ｍｏｏｒｅ－Ｐｅｎｒｏｓｅ广义逆［１］．Ａ＋ｙ存在当且仅当本文均作这一假设．在实际中,通常代替（１．１）的是扰动方程这里右端项,为一给定的误差水平,Ｑ是Ｙ到Ｒ（Ａ）的正交投影算子．对扰…     

A Newton type iterative method for heat-conduction inverse problems

An inverse problem for identification of the coefficient in heat-conduction equation is considered. After reducing the problem to a nonlinear ill-posed operator equation, Newton type iterative methods are considered. The implicit iterative method is applied to the linearized Newton equation, and the key step in the process is that a new reasonable a posteriori stopping rule for the inner iteration is presented. Numerical experiments for the new method as well as for Tikhonov method and Bakushikskii method are given, and these results show the obvious advantages of the new method over the other ones.     

Nonlinear implicit iterative method for solving nonlinear ill-posed problems

In the paper, we extend the implicit iterative method for linear ill-posed operator equations to solve nonlinear ill-posed problems. We show that under some conditions the error sequence of solutions of the nonlinear implicit iterative method is monotonically decreasing and, with this monotonicity, prove convergence of the new method for both the exact and perturbed equations.     

求解热传导反问题的一种正则化Newton型迭代法

讨论热传导方程求解系数的一个反问题.把问题归结为一个非线性不适定的算子方程后,考虑该方程的Newton型迭代方法.对线性化后的Newton方程用隐式迭代法求解,关键的一步是引入了一种新的更合理的确定(内)迭代步数的后验准则.对新方法及对照的Tikhonov方法和Bakushiskii方法进行了数值实验,结果显示了新方法具有明显的优越性.     

Reconstruction of high order derivatives by new mollification methods

In this paper, the problem of reconstructing numerical derivatives from noisy data is considered. A new framework of mollification methods based on the L generalized solution regularization methods is proposed. A specific algorithm for the first three derivatives is presented in the paper, in which a modification of TSVD, termed cTSVD is chosen as the regularization technique. Numerical examples given in the paper verify the theoretical results and show efficiency of the new method.     

渐近因子分离法及其在多项式求根中的应用

[1]提出了一种渐近分离多项式因子的方法,并考虑了在求根中的应用,但尚有许多问题没有解决,也没有给出实用的算法。其实Sebastiao,Silva早就提出过类似的方法。[1]和[2]都只考虑了f(x)没有重根的特殊情形,本文把渐近因子分离过程推广到任意f(x)的情形,并且给出了几种有实用价值的算法和两个实例。     

广义K.d.V.方程的数值方法

本文研究一般的广义K.d.V.方程的数值方法,给出了广义K.d.V.方程的一类半离散差分格式,证明了它们的守恒性。作者还严格证明了这类格式的广义稳定性,并由此推出收敛性。文章的最后考虑了全离散情形和两步格式。     

一种带噪声的周期函数数值微分方法

本文利用Thkhonov正则化方法讨论了带有噪声离散数据的周期函数的数值微分问题,证明了该方法存在唯一的三次周期样条函数解,并给出了其误差估计,而且从理论和数值例子说明了此方法的有效性．