On the rate of pointwise strong summability of orthogonal expansions

There is introduced a modificated local modulus of continuity as a measure of pointwise strong summability of expansion with respect to polynomial-like orthonormal system. The approximation versions and generalizations of the some special cases of the known results of K. Tandori [6], [7] and G. Freud [4] are obtained.     

On asymptotic pointwise nonexpansive mappings in modular function spaces

We prove the existence of fixed points of asymptotic pointwise nonexpansive mappings in modular function spaces.     

THE POINTWISE ESTIMATES TO SOLUTIONS FOR 1-DIMENSIONAL LINEAR THERMO-VISCO-ELASTIC SYSTEM

In this paper, we study the linear thermo-visco-elastic system in one-dimensional space variable. The mathematical model is a hyperbolic-parabolic partial differential system. The solutions of the system show some decay property due to the parabolicity. Based on detailed analysis on the Green function of the system, the pointwise estimates of the solutions are obtained, from which the generalized Huygens’ principle is shown.     

各向异性双3次Hermite元的超收敛性与点态超收敛性

本文研究了双三次Hermite 矩形元的超收敛问题. 利用双线性引理和Bramble-Hilbert引理, 在无正则性条件的假设下, 得到了双三次Hermite 矩形元的自然超收敛性及点态超收敛性结果.该结论与传统的有限元正则条件下的结论一致; 与传统的超收敛分析方法-积分恒等式法相比, 本文的方法既简单又便于推广.     

Uniform error estimates in the finite element method for a singularly perturbed reaction-diffusion problem

Consider the problem with homogeneous Neumann boundary condition in a bounded smooth domain in . The whole range is treated. The Galerkin finite element method is used on a globally quasi-uniform mesh of size ; the mesh is fixed and independent of .

A precise analysis of how the error at each point depends on and is presented. As an application, first order error estimates in , which are uniform with respect to , are given.

     

Pointwise approximation of corner singularities for a singularly perturbed reaction-diffusion equation in an -shaped domain

A singularly perturbed reaction-diffusion equation is posed in a two-dimensional -shaped domain subject to a continuous Dirchlet boundary condition. Its solutions are in the Hölder space and typically exhibit boundary layers and corner singularities. The problem is discretized on a tensor-product Shishkin mesh that is further refined in a neighboorhood of the vertex of angle . We establish almost second-order convergence of our numerical method in the discrete maximum norm, uniformly in the small diffusion parameter. Numerical results are presented that support our theoretical error estimate.

     

Fourier级数的点态（e,c) 可和性

级数∑_0~∞a_n为(e,c)(c>0)可求和是指极限     

Maximal theorems for the directional Hilbert transform on the plane

For a Schwartz function on the plane and a non-zero define the Hilbert transform of in the direction to be

p.v.

Let be a Schwartz function with frequency support in the annulus , and . We prove that the maximal operator maps into weak , and into for . The estimate is sharp. The method of proof is based upon techniques related to the pointwise convergence of Fourier series. Indeed, our main theorem implies this result on Fourier series.

     

On pointwise bounded approximation

Let G be an open subset in the extended complex plane and let A（G） denote the algebra of all functions analytic on G and continuous on G. We call a domain multi-nicely connected if there is a circular domain W and a conformal map ~ from W onto G such that the boundary value function of φ is univalent almost everywhere with respect to the arclength on aW. Suppose that every component of G is finitely connected and none of the components of G have single point boundary components. We show that for every bounded analytic function on G to be the pointwise limit of a bounded sequence of functions in A（G）, it is necessary and sufficient that each component of G is multi-nicely connected and the harmonic measures of G are mutually singular. This generalizes the corresponding result of Davie for the case when the components of G are simply connected.     

INTERSECTION OF TRANSLATIONS OF CANTOR TRIADIC SET

Let C be the Cantor triadic set and let Cα=C+α={β+α: β∈C} for -1≤α≤ 1. Let Hp={α∈C: dim H(Cα∩C)=dim B(C α∩C)=(1-p)log 2/log 3}, 0＜ p＜ 1. The authors give the dimensions of C α∩C and Hp. In additionthe characteristic of Hp is described by means of some measure μ supported on C.