再谈中值定理“中间点”的渐近估计

在较一般的条件下,本文讨论了当b→a~+时,积分中值定理∫_a~bf(x)g(x)dx=f(ξ)b∫_a~bg(x)dx的“中间点”ξ的渐近估计.     

关于《一元线性模型最小二乘估计的强相合性》的注记

通过直接考虑随机误差变量的方差,研究了一元线性模型最小二乘估计的强相合性,所给定理减弱并简化了[1]的条件和形式,从而推广了结果、扩大了应用范围。     

关于P—调和障碍问题解之正则性

本文讨论一类向量值泛函在障碍约束下的极小化问题，得到了此类问题有界解之存在性和部分正则性。     

对流扩散方程基于三次自然样条插值特征差分方法

针对一维对流扩散方程提出了基于三次自然样条插值的特征差分格式，给出了L2模误差估计武．数值算例表明，本文格式在很大程度上消除了插值误差对计算格式的影响．     

具有声学边界条件的非线性波动方程的整体解

研究具有声学边界条件的非线性波动方程初边值问题,得到整体强解的存在惟一性.     

协方差改进法在半相依回归模型中的应用

文章系统地总结了协方差改进法及两步协方差改进法在半相依回归模型中的应用，推导了协方差改进估计的具体表达形式。     

Error Estimation and Optimization of the Functional Algorithms of a Random Walk on a Grid Which Are Applied to Solving the Dirichlet Problem for the Helmholtz Equation

We consider the algorithms of a random walk on a grid which are applied to global solution of the Dirichlet problem for the Helmholtz equation (the direct and conjugate methods). In the metric space C we construct some upper error bounds and obtain optimal values (in the sense of the error bound) of the parameters of the algorithms (the number of nodes and the sample size).     

About the sharpness of the stability estimates in the Kreiss matrix theorem

One of the conditions in the Kreiss matrix theorem involves the resolvent of the matrices under consideration. This so-called resolvent condition is known to imply, for all , the upper bounds and . Here is the spectral norm, is the constant occurring in the resolvent condition, and the order of is equal to .

It is a long-standing problem whether these upper bounds can be sharpened, for all fixed 1$">, to bounds in which the right-hand members grow much slower than linearly with and with , respectively. In this paper it is shown that such a sharpening is impossible. The following result is proved: for each 0$">, there are fixed values 0, K>1$"> and a sequence of matrices , satisfying the resolvent condition, such that for .

The result proved in this paper is also relevant to matrices whose -pseudospectra lie at a distance not exceeding from the unit disk for all 0$">.

     

L^2（R^n） Boundedness for a Class of Multilinear Singular Integral Operators

The L^2(R^n) boundedness for the multilinear singular integral operators defined by TAf(x)=∫R^nΩ（x-y）/|x-y|^n 1(A(x)-A(y)-△↓A(y)(x-y))f(y)dy is considered,where Ω is homogeneous of degree zero,integrable on the unit sphere and has vanishing moment of order one,A has derivatives of order one in BMO(R^n） boundedness for the multilinear operator TA is given.     

Notes on the Norm Estimates for the Sum of Two Matrices

This is a lecture note of my joint work with Chi-Kwong Li concerning various results on the norm structure of n x n matrices (as Hilbert-space operators). The main result says that the triangle inequality serves as the ultimate norm estimate for the upper bounds of summation of two matrices.In the case of summation of two normal matrices, the result turns out to be a norm estimate in terms of the spectral variation for normal matrices.