广义ω-Calderón-Zygmund算子的有界性

本文证明了广义ω-Calderón-Zygmund算子是HA_ω^p到HA^p的有界算子.     

Szász型算子线性组合的同时逼近

本文利用ω^2r_φλ(f,t)代替ω^r_φλ(f,t)给出了Szász-Kantorovich算子线性组合同时逼近的估计。     

球上Zygmund 型空间上的加权Cesàro 算子

该文在Cⁿ中单位球上讨论了Zygmund 型空间(小Zygmund 型空间)之间的加权Cesàro 算子T_g 的有界性和紧性特征, 得到了以下的结果: (1) T_g 是Z^p 到Z^q的有界算子或紧算子的充要条件; (2) T_g 是 Z^p₀ 到Z^q₀ 的有界算子或紧算子的充要条件.     

Bernstein算子的逼近

本文利用点态光滑模ωφλ2r(f,t)研究了Bernstein算子的r阶线性组合的点态逼近.当1-1/r≤λ≤1时,用ωφλ2r(f,t)给出了—个点态逼近等价定理.且用反例说明了当0≤λ<1-1/r 时,此结论不成立.但若限制0<αφλ2r(f,t)给出     

关于广义Calderon－Zygmund算子

本文讨论了θ（ｔ）型和（ｌｏｇ，θ）型Ｃａｌｄｅｒóｎ－Ｚｙｇｍｕｎｄ算子在加权Ｈａｒｄｙ型空间ＨＡ_w^p上的有界性，θ（ｔ）型Ｃａｌｄｅｒóｎ－Ｚｙｇｍｕｎｄ算子在Ｈａｒｄｙ型加权块空间上的有界性，以及广义的ｗ－Ｃａｌｄｅｒóｎ－Ｚｙｇｍｕｎｄ算子是Ｈ^Ap_w到ＨＡ^p上的有界算子．     

关于复平面上H∞空间,βp空间以及β0p空间的几个问题

本文讨论了单位圆中Hardy空间H^∞到p-Bloch空间β^p的复合算子T_1,φ加权复合算子T_ψ,φ的有界性,也讨论了H^∞到小p-Bloch空间β₀^p的复合算子T_1,φ的有界性问题;另外还讨论了小p-Bloch空间到H^∞空间的点乘子及小p-Bloch空间上复合算子的紧性等.     

一类具多重特征的无解算子

本文给出一类型如P(x,D)=D₁⁴+x₁⁴D₂⁴-(i^1/2+(-i)^1/2)D₁²D₂+4x₁D₁D₂²-i(i^1/2-(-i)^1/2)x₁²D₂³+(1+2i)D₂²+C 或更一般地p(x,D)=L^tL(x,D)+C(L为无解算子)的多重特征算子。指出包括零阶项在内的低阶项对局部可解性能具有决定性影响。具体地说,在原点邻域上面所给算子p(x,D)的主部D₁⁴+x₁⁴D₂⁴为可解算子,当C=0时P(x,D)为不可解算子。但当C>0时又变为局部可解算子。类似地讨论了算子附加零阶项的一些情况。文章最后证明了当自由项f具形|x₁|ψ＇(x₂)(ψ为实函数)时,在原点邻域有古典解的充要条件为ψ(x₂)解析。     

二元三次样条空间S31,2(Δmn(2)) 的样条拟插值

本文首先利用由两组具有局部最小支集的样条所组成的基函数,构造非均匀2 型三角剖分上二元三次样条空间S₃^1,2(Δ_mn⁽²⁾)的若干样条拟插值算子. 这些变差缩减算子由样条函数B_ij¹支集上5 个网格点或中心和样条函数B_ij²支集上5 个网格点处函数值定义. 这些样条拟插值算子具有较好的逼近性,甚至算子V_mn（f） 能保持近最优的三次多项式性. 然后利用连续模,分析样条拟插值算子V_mn（f）一致逼近于充分光滑的实函数. 最后推导误差估计.     

非周期函数类WrHω的宽度估计

In this paper, we obtain the strong assymptotic values of n-width d_n(W^rH^ω, C)and d_n(W^rH^ω, L) for non-periodic function class W^rH^ω, wheve ω is a concave modulus of continuity.     

Cn中单位球上&mu|-Bloch空间之间的加权复合算子

设 μ 和 ν 是[0,1)上两个正规函数, 该文给出了Cⁿ(n>1)中单位球上Bloch型空间β_μ 到β_ν 之加权复合算子T_ψ,φ为有界算子和紧算子的充要条件.     

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.