变系数高阶中立型泛函数分方程的振动性与渐近性

考虑变系数高阶中立型泛函微分方程ｄ＾ｎ／ｄｔ＾ｎ（ｘ（ｔ）＋ｐ（ｔ）ｘ（ｔ－τ（ｔ））＋ｍ∑ｉ＝１Ｐｉ（ｔ）ｘ（ｔ－τｉ（ｔ）＝０，在－１＜ｐ（ｔ）≤０情形下解的振动性与渐近性，取消了Ｐｉ（ｔ）≥ｑｉ＞０的限制，改进以往的相应结果，本文结果时高阶泛函方程Ｘ＾（ｎ）（ｔ）＋ｍ∑ｉ＝１ｐｉ（ｔ）ｘ（ｔ－τｉ（ｔ））＝０也是适用的。     

一类二阶中立型方程的周期解

利用Ｆｏｕｒｉｅｒ级数理论，研究了一类二阶中立型方程ｘ（ｔ）＋ａ１ｘ（ｔ）＋ａ２ｘ（ｔ）＋ｍ／∑ｉ＝１《ｕｉｘ（ｔ－ｈｉ）＋ｕｉｘ（ｔ－ｈｉ）＋ｗｉｘ（ｔ－ｈ）ｉ］＝ｆ（ｔ）的周期解问题，获得了保证其具有连续二阶导数的周期解存在唯一的些简便的充分条件。     

关于МОФОНЪКО不等式的精确性

证明了如下定理：设Φ（ｚ）＝Σ↑ｎ↓ｕ＝１∏↑ｔ↓ｉ＝１ｆｉ＾ａ＾ｕｉ０…（ｆｉ＾（ｋｉ））＾ａｉｋｉ＾ｕ／Σ↑ｍ↓ｖ＝１∏↑ｔ↓ｉ＝１ｆｉ＾ｂ＾ｖｉ０…（ｆｉ＾（ｋｉ））＾ｂｉｋｉ＾ｖ其中ｆｉ（ｚ），（１≤ｉ≤ｔ）是亚纯函数，ａｉｊ＾ｕ，ｂｉｊ＾ｖ为非负整数，则有Ｔ（ｒ，Φ）≤Σ↑ｔ↓ｉ＝１｛［Ｓｉ＋ｏ（１）］ｍ（ｒ，ｆｉ）＋［△ｉ＝ｕｉ＋ｏ（１）］Ｎ（ｒ，ｆｉ）＋（△ｉ－Ｓｉ）Ｎ↑－（ｒ，ｆｉ     

变系数一阶中立型微分方程的振动性

考虑了微分方程［ｘ（ｔ）－ｐｘ（ｔ－τ）］′＋∑ｎｉ＝１Ｑｉ（ｔ）ｘ（ｔ－τｉ）＝０ｔ≥ｔ０（１）其Ｐ∈Ｒ＋＝［０,∞）,τ,τｉ为正常数,Ｑｉ（ｔ）∈Ｃ（［ｔ０,∞）,Ｒ＋）（ｉ＝１,２,…,ｎ）且∑ｎｉ＝１∫∞ｔ０Ｑｉ（ｔ）ｄｔ＝∞,获得了方程（１）振动的几个充分条件;减弱了文［１］Ｑ（ｔ）为周期系数的条件,推广和改进了文［１］的相应结果,并且有一些结果是新的     

红血球补充模型的全局吸引性

研究动物体内红血球补充模型 Ｎ（ｔ） ＝ ｒ（ｔ）（－ μ Ｎ（ｔ） ＋ ∑ｍｉ＝ ０ Ｐｉｅ－ ｒｉ Ｎ （ｔ－ τｉ） ）， ｔ ≥０其中 ｒ（ｔ） ∈ Ｃ（［０， ＋ ∞），（０， ＋ ∞））， Ｐｉ，ｒｉ，τｉ（ｉ＝ ０，１，…，ｍ － １） ∈［０， ＋ ∞）， Ｐｍ＞ ０，ｒｍ ＞ ０，τｍ ＞ ０，μ＞ ０，证明了如果 　　　　∫ｔｔ－ τｒ（ｓ）ｄｓ ≤ Ｂ，∫∞０ ｒ（ｓ）ｄｓ ＝ ＋ ∞．则方程的正平衡点是全局吸引子．     

一类时滞神经网络模型的稳定性

利用Ｌｙａｐｕｎｏｖ泛函,讨论了一类时滞神经网络模型ｕ′ｉ（ｔ）＝－ｂｉｕｉ（ｔ）＋∑ｎｊ＝１Ｔｉｊｆｊ（μｊｕｊ（ｔ－τｊ））＋ｃｉτｊ≥０,ｉ＝１,２,…,ｎ平衡态的稳定性,获得了几个充分条件     

线性常微分方程组解的特征数的估计

复数域上线性系统ｘ＝Ａ（ｔ）ｘ，当Ａ（ｔ）＝（ａｉｊ（ｔ））ｎ×ｎ具有（ｎ，Ｎ，ｒ） 差异性质且ｒｎ时，解的特征数ｊ有估计λｊ－ｌｉｍｔ→∞１ｔ∫ｔｔ０Ｒｅａｊ（τ）ｄτｎ－１ｒ＋１－ｎｌｉｍｔ→∞１ｔ∫ｔｔ０Ａ（τ）ｄτ，ｊ＝１，２，…，ｎ，其中Ａ（ｔ）＝ｍａｘ｛｜ａｉｊ（ｔ）｜：ｉ，ｊ＝１，２，…，ｎ，ｉ≠ｊ．｝     

向量自激门限自回归（VSETAR）序列的遍历性

本文主要考虑二维自激门限自回归模型：Ｘ（ｔ）＝Ｉ［Ｘ（ｔ－１）∈Ｒｉ］ＡｉＸ（ｔ－１）＋ε（ｔ），其中Ａｉ（ｉ＝１，２，３，４）为２×２系数矩阵，｛ε（ｔ）｝为二维ｉ．ｉ．ｄ序列。我们得到｛Ｘ（ｔ）｝为遍历的四个充分条件。     

变量满足多个线性关系且部分变量带误差的回归分析

考虑独立变量ａ１ｔ，ａｐｔ，它们满足ｍ（≥１）个线性回归关系，ｐΣｊ＝１ｂｉｊａｊｔ＝ｃｉ，ｉ＝１，ｍ，这些变量中的一些，比如ａｉｔ（ｉ＝ｒ＋１，ｐ）可以被确切观测到，而另一些变量的观测值带有误差。即ａｉｔ的观测值为ｘｉｔ＝ａｉｔ＋∈ｉｔ（ｉ＝１，ｒ，ｔ＝１，ｎ），而ｘｉｔ＝ａｉｔ（ｉ＝ｒ＋１，ｐ，ｔ＋１，ｎ），在?ｔ＝（∈１ｔ，∈ｒｔ）ｔ，ｔ＝１，ｎ为ｉｉｄ。且Ｅ∈ｔ＝０，Ｅ∈ｔ∈ｔｒ＝σ＾２Ｉ     

稳定分量过程的图集的Packing测度

本文考虑Ｒ~ｄ中具有如下形式的过程：Ｘ（ｔ）＝（Ｘ_１（ｔ），Ｘ_２（ｔ），…，Ｘ_Ｎ（ｔ）），其中Ｘ_ｉ（ｔ）为Ｒ~ｄｉ中指标为α_ｉ的稳定过程（１≤ｉ≤Ｎ），Ｘ_１（ｔ），…，Ｘ_Ｎ（ｔ）相互独立，ｄ＝ｄ１＋…＋ｄ_Ｎ．通过讨论过程Ｇ（ｔ）＝（ｔ，Ｘ（ｔ））的逗留时分布的渐近性质，研究图集Ｇ［０，１］的Ｐａｃｋｉｎｇ测度函数问题。获得了ψ－ｐ（Ｇ［０，１］）＝０或＋∞的积分判别法，或者其确切测度函数．     

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.     

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.     

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.     

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     

Bounds for the zeros of polynomials

Let P(z)=∑↓j=0↑n ajx^j be a polynomial of degree n. In this paper we prove a more general result which interalia improves upon the bounds of a class of polynomials. We also prove a result which includes some extensions and generalizations of Enestrǒm-Kakeya theorem.     

Boundedness of commutators related to Marcinkiewicz integrals on hardy type spaces

In this paper, the authors study the boundedness of the operator [μΩ, b], the commutator generated by a function b ∈ Lipβ(Rn)(0 ＜β≤ 1) and the Marcinkiewicz integrals μΩ, on the classical Hardy spaces and the Herz-type Hardy spaces in the case Ω∈ Lipα(Sn-1)(0 ＜α≤ 1).     

Jacobi polynomials used to invert the laplace transform

Given the Laplace transform F(s) of a function f(t), we develop a new algorithm to find an approximation to f(t) by the use of the classical Jacobi polynomials. The main contribution of our work is the development of a new and very effective method to determine the coefficients in the finite series expansion that approximation f(t) in terms of Jacobi polynomials. Some numerical examples are illustrated.     

Generalization of the interaction between Haar approximation and polynomial operators to higher order methods

In applications it is useful to compute the local average empirical statistics on u. A very simple relation exists when of a function f（u） of an input u from the local averages are given by a Haar approximation. The question is to know if it holds for higher order approximation methods. To do so, it is necessary to use approximate product operators defined over linear approximation spaces. These products are characterized by a Strang and Fix like condition. An explicit construction of these product operators is exhibited for piecewise polynomial functions, using Hermite interpolation. The averaging relation which holds for the Haar approximation is then recovered when the product is defined by a two point Hermite interpolation.