一类非线性双曲方程整体弱解的存在性及能量衰减性

讨论了一类非线性双曲方程u_u-m(‖▽u‖_2~2)△u-γ△u_t=β|u|~αu的初边值问题整体弱解的存在性和指数衰减..     

一类平均曲率型抛物方程解的存在性和解的熄灭

在Rn有界域上考虑一类带有非线性迁移项的平均曲率型方程div{σ(|　Δu|2)　Δu}+b(u)·　Δu=0的第一类初边值问题.主要得到了弱解的存在性,并且给出了解的熄灭性质及解的L∞估计.     

一个带非线性项的退化四阶抛物方程弱解的存在性

讨论一个带非线性项的退化四阶抛物方程的初边值问题,在一些初值的假定下,证明了弱解的存在性.     

关于具有阻尼项的扩散方程

文章研究了具有阻尼项的扩散方程?u/?t=div(ρα|▽u|p-2▽u)-a(x)|▽u|q,讨论了该方程的初边值问题解的存在性,其中α＞0,q＜p,ρ(x)=dist(x,?Ω)是空间变量到边界?Ω的距离函数,a(x)是已知非负有界函数.作者利用抛物正则化的方法,证明了方程弱解的存在性.通过对检验函数的适当选取,可...     

非线性退缩抛物型方程弱解的梯度的Holder连续性

本文我们讨论如下的非线性退缩抛物型方程：设为上述方程的弱解．在一些结构性条件下，我们得到△ｕ的Ｈ　ｌｄｅｒ连续性．     

一个非散度型的退化抛物型方程

本文讨论非散度型的退化扩散问题(1) 主部是呈散度型的退化扩散问题已得到了广泛的研究(如见仁[1]),对于非散度型的退化抛物型方程,已有的工作甚少。[2]研究了φ(u)=u时的问题(1),得出其弱解的存在性,局部性,并讨论了唯一性。     

拟线性抛物方程的弱解

该文给出了拟线性退化抛物方程pa_t{u}+pa_x{f(u)}=pa_xx{A(u(x,t))}∈R^2_+×(0,+∞) ,u(x,0)=u_0(x),x∈R 一种弱解的新定义, 利用Div Curl引理证明了解的存在性．     

R2上一类非线性抛物方程弱解的渐近性态

本文研究R2上一类非线性抛物方程弱解的渐近性态,利用改进的Fourier分解方法,证明了其解在L2范数下的衰减速率为(1 t)-12,与在相同初值条件下线性热方程解的衰减速率是一致的.     

一类强退化抛物方程弱解的惟一性

研究了如下形式的强退化抛物方程(C)(u)/(t)=(2A(u,x,t))/(x2)+(B(u,x,t))/(x),基于Holm gren方法,证明了弱解的惟一性.     

乘子空间中广义Navier-Stokes方程弱解的正则性准则(英文)

利用能量估计与不等式研究三维广义Navier-Stokes方程弱解的正则性准则,证明如果速度场的水平分量ū=(u1,u2,0)满足ū∈L2α-(r+1)2α(0,T;r),r∈[0,1),或者水平速度场的水平梯度▽hū=(α1ū,α2ū)满足▽hū∈L2α-r2α(0,T;r),r∈[0,1],则弱解在[0,T)是唯一的强解.     

RECENT PROGRESS ON SPHERICAL HARMONIC APPROXIMATION MADE BY BNU RESEARCH GROUP ——In memory of Professor Sun Yongsheng

As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years （2001-2005）. The main topics are： convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths.     

On a class of self-similar processes with stationary increments in higher order Wiener chaoses

We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals.     

On a class of Riemann surfaces

It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary.     

A REPRESENTATION FORMULA RELATED TO SCHR(O)DINGER OPERATORS

Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V.     

Boundedness for commutators of multipliers on Hardy type spaces

In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p（R^n） into the Lebesgue space L^p with p 〈 1.     

A unified approach to certain problems of best local approximation

In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms.     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

<正>August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists     

Towards Excellence in Science Chinese Academy of Sciences

<正>May 26,2014,Beijing Science is a human enterprise in the pursuit of knowledge.The scientific revolution that occurred in the 17th Century initiated the advances of modern science.The scientific knowledge system created by