时空离散FitzHugh-Nagumo方程解的渐近行为

本文用有限差分格式对FitzHugh-Nagumo方程的时间变量和空间变量同时离散，给出了离散模型整体吸引子存在的条件。     

一类有条件异方差的非线性自回归模型的高阶矩

本文对一类非线性时间序列模型ｘｔ＝φ（ｘｔ－１，…，ｘｔ－ｐ）＋εｔｈ（ｘｔ－１，…，ｘｔ－ｐ）给出了高阶矩的存在条件。     

一维Dirac-Klein-Gordon方程组解的存在时间

本文研究具弱衰减、小初值初始条件的一维Dirac－Klein－Gordon方程组解的存在时间估计问题，结果表明这类问题解的存在时间几乎比e－4大初值的弱衰减条件使得通常的方法不能使用，在此，通过利用Delort曾用过的方程组特征的曲率性质以及2次微局部椭圆正则性解决了该问题.     

奇异随机Markov跳变系统的N人Nash博弈问题

分别研究了有限时间和无限时间情形下的一类奇异随机Markov跳变系统的N人微分博弈问题.利用配方法,得到了有限时间N人博弈的Nash均衡策略的微分Riccati方程,证明了Nash均衡策略的存在条件等价于微分Riccati方程存在解;无限时间内,N人博弈的Nash均衡策略的存在条件等价于代数Riccati方程存在解,并分别给出了均衡策略的显式表达及最优性能泛函值.最后,将所得的结果应用于现代鲁棒控制中的随机H_2/H_∞控制问题,得到了鲁棒控制策略的存在条件及显式表达.     

关于非稳态反应扩散对流方程的死核问题

本文研究非稳态反应扩散对流方程ｕｔ＝△ｕ－ｆ（ｕ，Ｄｕ）的死核问题，给出了一些死核存在的充分条件、死核形成时间的估计和死核大小的估计．     

具非线性控制变量的非自治松驰系统时间最优追踪控制问题中的若干结果

本文讨论了一类广义非自治离散松驰系统的时间最优控制问题，将R^n中点曲线的目标约束推广为凸集值函数的超曲线约束．在证明了松驰系统与原系统可达集相等的基础上，得到了最优控制的存在性．由凸集分离定理及终端时间闺值函数方程，我们获得了最大值原理及最优控制时间的确定方法．较之Hamilton方法，本文的条件更一般．离散松驰系统的相关结论可以用于分散控制．     

非线性边界条件下高维拋物方程解的全局存在性及爆破现象

该文研究了非线性边界条件下高维空间上更一般化的非线性抛物问题解的爆破现象以及全局解的存在性.通过构造辅助函数,并对方程中的已知数据项进行一些必要的假设,应用微分不等式技术,当爆破发生时推导了爆破时间的下界.也推到了方程的解一定发生的条件并得到了爆破时间的上界.同时,不管方程对外施力还是受到外力的作用,也研究了方程的解全局存在的条件.     

非对称稳定幂GARCH的严平稳性与解的唯一性

平稳性是研究时间序列的重要条件，本讨论一个扰动项为非对称稳定幂GARCH过程的模型的严平稳性与解的唯一性，并给出严平稳性与解存在的充要条件。     

非自治Lotka-Volterra扩散模型的持续生存与周期轨道(英)

本文研究了一类非自治的捕食者一食饵扩散模型；其中食饵能在环境相异的两个缀块间有限制地扩散，但对捕食者来说，缀块间的扩散不受任何限制；另外假设模型的系数都是时间的函数．我们证明了在适当的条件下，这个系统能够持续生存，进一步给出了系统存在唯一全局渐近稳定正周期轨道的充分条件．     

一个可修系统的最优更换模型

本文考虑了单部件、一个修理工组成的可修系统，在故障系统不能“修复如新”的前提下，我们利用几何过程，以系统年龄Ｔ为策略，选择最优的Ｔ使得系统经长期运行单位时间的期望效益达到最大．本文还在一定的条件下证明了最优更换策略Ｔ的唯一存在，且求出了系统经长期运行单位时间的最大期望效益的明显表达式．     

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.     

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.     

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.     

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