Toader型平均与几种经典平均的确界

给出了最佳参数α_1,α_2,α_3,β_1,β_2,β_3∈R,使得双向不等式α_1Q(a,b)+(1-α_1)G(a,b)0且a≠b成立.其中A(a,b)=(a+b)/2,H(a,b)=2ab/(a+b),G(a,b)=(ab)~(1/2),Q(a,b)=((a~2+b~2)/2)~(1/2),C(a,b)=(a~2+b~2)/(a+b),T(a,b)=2/π∫_0~(π/2)(a~2cos~2t+b~2sin~2)~(1/2)tdt分别是两个正数a和b的算术平均,调和平均,几何平均,二次平均,反调和平均和Toader平均.     

一个定理的再推广

定理若函数f-1(x),g-1(x)分别是函数f(x),g(x)的反函数(下同),且g-1(x)=g(x),则方程f(x)=g(x)有根a方程f-1(x)=g(x)有根g(a).证由f(a)=g(a),可得f-1(g(a))=a=g-1(g(a))=g(g(a)),即方程f-1(x)=g(x)有根g(a).由f-1(g(a))=g(g(a))=g-1(g(a))=a得f(a)=g(a),即方程f(x)=g(x)有根a.推     

一类基于量子环面非交换结合代数的模

在量子环面[1]上构造一类非交换结合代数AQ-模M(a,b),我们还刻划了AQ-模的结构并揭示[2]一类商模序列:每个商模Mn(a)/Mn+1(a)都同构于M(a,0),每个商模的自同构群AutMn(a)/Mn+1(a)均与C*同构.     

北大保送试题与代数基本定理

题目 已知f(x)是二次函数,且a,f(a),f(f(a)),f(f(f(a)))构成正项等比数列,求证:f(a)=a. 证明:设f(a)=qa(q＞0),则f(f(a))=q2a,即f(qa)=q2a;同理有f(q2a)=q3a.     

连立方根序列的收敛性及其估值不等式

研究了连立方根序列{Sn(a)}:Sn(a)=3a+3a+…+3a(n个根号),n∈N,a∈R的收敛性,并得到了一些与序列Sn(a)相关的不等式.     

涉及例外函数与分担函数的正规族

设F是区域D内的一族亚纯函数,a(z),b(z),c(z)是区域D内三个判别的亚纯函数,其中一个可以恒为无穷,且对于任意z∈D,a(z)≠b(z),a(z)≠c(z),b(z)≠c(z),S={a(z),b(z),c(z)}.若对于任意两个函数f,g∈F,f与g在D内分担集合S,则F在D内正规.该结果推广了著名的Montel正规定则.     

一类双曲型方程反问题的存在性与唯一性

针对双曲型方程定解问题{utt=a2uxx+f(t),0xπ,a∈R且a≠0,u(0,t)=v1(t),u(π,t)=v2(t),t0,u(x,0)=g(x),ut(x,0)=h(x),0≤x≤π研究了可以唯一决定未知函数组{v1(t),v2(t),f(t)}的基本条件,提出了该定解问题的反问题,并且讨论了此反问题的存在性与唯一性.     

Neuman平均与算术平均、反调和平均的最佳不等式

给出了关于Neuman平均NQA(a,6),NQA(a,b)与算术平均A(a,b)和反调和平均C(a,b)的两个最佳双向不等式,所得结论加细了已知结果.     

极限函数的连续性与一致收敛性的关系

<正> 我们知道:如果f_1(x),f_2(x).…,f_n(x)…都在[a,b]上连续且f_1(x),f_2(x)…,f_n(x),…在[a,b]上一致收敛于f(x),那末f(x)必在[a,b]上连续.现在我们提出一个相反的问题:如果f_1(x),f_2(x),…,f_n(x),…都在[a,b]上连续,且f_1(x),f_2(x),…,f_n(x),…在[a,b]上收敛于     

二阶模糊线性微分方程边值问题的模糊近似解

讨论了二阶模糊线性微分方程边值问题{y"+p(t)y'+q(t)y=g(t),t∈[a,b],t∈[a,b]y(a)=(a),y(b)=(β),(α),(β)∈E1的模糊近似解,即利用配置法将微分方程转化为函数线性方程组,针对其系数函数的符号的不同,通过计算函数线性方程组获得了原模糊微分方程的模糊近似解.     

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.     

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.