两类非线性发展方程的新的显式解

应用指数函数法,得到了(1+1)维Sinh-Gordon方程、(2+1)维Boiti-Leon-Manna-Pempinelli(BLMP)方程的一些新的显式解.     

(2+1)-维破裂孤子方程的群叶状方法和显式解

利用等变活动标架理论,研究(2+1)-维破裂孤子方程的群叶状方法和显式解.原方程的对称群的无穷维部分被用来产生整个解空间的叶状结构,于是分解系统就继承了对称群的有限维部分.求解的过程完全符号化和算法化.利用群叶状方法,破裂孤子方程的一些显式精确解被得到,这些解关于无穷维对称子群封闭.     

新(2+1)-维MKP方程的精确行波解

利用平面动力系统方法,在不同的参数条件下,获得了对应行波系统的相图.给出了新(2+1)-维MKP方程的五个行波解的精确参数表达式.     

(2+1)维非线性Schr(o)dinger型方程的同宿轨道

研究了几类(2 1)维非线性Schr(o)dinger型方程同宿轨道的问题.利用Hirota双线性算子方法, 通过给出的相关变换, 得到了包括(2 1)维的长短波相互作用方程, 广义Zakharov方程, Mel'nikov方程和g-Schr(o)dinger方程的同宿轨道解的显式解析表达式,从而讨论了这些方程的同宿轨道.     

Wick型随机(2+1)维Broer-Kaup方程的Bcklund变换和白噪声泛函解(英文)

本文对(2+1)维变系数Broer-Kaup方程和 wick型随机(2+1)维Broer-Kaup方程进行了研究,利用 Hermite变换、齐次平衡法以及tanh函数法给出了wick型随机(2+1)维Broer-Kaup方程的Bcklund变换和白噪声泛函解.     

一个综合植被地表径流与饱和地下水流之间相互作用的数值模型

构建一个综合的数值模型,用来处理植被地表径流与饱和地下水流之间的相互作用问题.综合了早先提出的准三维植被地表径流模型,与二维饱和地下水流模型建立起该数值模型.植被地表水流模型被构建为,二维浅水方程(SWE)显式的有限体积解,耦合了Navier-Stokes方程(NSE)隐式的有限差分解,得到了竖向速度的分布.地下水流模型是以二维饱和地下水流方程(SGE)显式的有限体积解为基础构建.通过在连续方程中引入源-汇项,达到植被地表径流和地下水流之间的相互作用.单一的规则将2个解紧密地耦合在一起.最后,应用4个案例来验证本综合模型,结果是令人满意的.     

Wick型随机(2+1)维Broer-Kaup方程的B(a)cklund变换和白噪声泛函解

本文对(2+1)维变系数Broer-Kaup方程和wick型随机(2+1)维Broer-Kaup方程进行了研究,利用Hermite变换、齐次平衡法以及tanh函数法给出了wick型随机(2+1)维Broer-Kaup方程的B(a)cklund变换和白噪声泛函解.     

利用推广的(G'/G)展开法求解(2+1)维BBM方程

利用推广的(G'/G)展开法,借助于计算机代数系统Mathematica,获得了(2+1)维BBM方程的丰富的显式行波解,分别以含两个任意参数的双曲函数、三角函数及有理函数表示.     

利用推广的(G′/G)展开法求解(2+1)维BBM方程

利用推广的(G′/G)展开法,借助于计算机代数系统Mathematica,获得了(2+1)维BBM方程的丰富的显式行波解,分别以含两个任意参数的双曲函数、三角函数及有理函数表示.     

解二维抛物型方程的高精度显式差分格式

<正> 1 引言从扩散、渗流、热传导等问题中可以提出很多抛物型方程。对于一维的抛物型方程u_1=σu_(xx)(σ>0),文[1]给出了一个截断误差为O(△t~2+△x~4)的高精度显式差分格式,对于二维的抛物型方程u_t=σ(u_(xx)+u_(yy))(σ>0),文[2]给出了截断误差为O(△t~2+△x~2+△y~2)的绝对稳定的显     

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.     

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.     

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     

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     

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).     

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.     

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.