可补为可逆2×2分块算子缺项矩阵

本文给出了缺项算子矩阵可补为可逆算子矩阵，且它的逆矩阵的一块等于已知矩阵的条件，同时给出了问题解的一般形式，对可补为可逆自共轭算子的问题也进行了一些讨论．     

关于一类分块矩阵弱相似性质的理论探讨

本文提出了分块矩阵弱相似的概念,探讨了分块矩阵弱相似的条件和性质,得到了若干有意义的结果,为解决有关实际问题提供了一定的理论依据。     

矩阵对角化的弱可逆矩阵刻画

引入弱可逆矩阵,并用它来刻画矩阵可对角化的充要条件.     

用线性弱正算子逼近

用线性正算子的逼近理论飞速发展,但正性是一个较强的限制,孙永生,王仁宏等研究过减弱正性限制,作者研究用线性弱正算子逼近,推广Korovkin定理和Grundmann定理等等.     

Matrix Summability and Positive Linear Operators

In the present paper we prove a Korovkin type approximation theorem for a sequence of positive linear operators acting from a weighted space C_ρ1 into a weighted space B_ρ2 with the use of a matrix summability method which includes both convergence and almost convergence. We also study the rates of convergence of these operators.     

Selfadjointness of Integral and Matrix Operators

Criteria for selfadjointness of integral operators, includingmatrix operators, based on our earlier domination results areestablished. The range of applicability is elucidated by carefullychosen examples, not covered by previously known criteria.     

求分块三对角矩阵和分块周期三对角矩阵逆矩阵的快速算法

给出了分块三对角矩阵逆矩阵的快速算法,并利用所给算法得到了求分块周期三对角矩阵逆矩阵的快速算法.最后通过算例表示算法的有效性.     

富里算子及共轭变换的弱有界性

石油资源已频临日益枯竭的境地,因而对内燃机代用燃料的研究广泛廾展,植物油做为柴油机代用燃料的研究已遍布世界各国,本文主要介绍国内外植物油燃料的试验研究情况,植物油与其他代用燃料的比较,以及对发展我国植物油燃料的研究谈一些看法,提出一些具体建议。     

Ounded Operators on Weak Hardy Spaces and Applications

The atomic decomposition of weak Hardy spaces consisting of Vilenkin martingales is formulated. Some sufficient conditions for a sublinear operator T to be bounded from the weak Hardy space wHp to the weak wLp space are given. As applications a weak version of the Hardy-Littlewood inequality is obtained and it is shown that the maximal operator of the Cesàro means of a Vilenkin-Fourier series is bounded from wHp to wLp and is of weak type (1, 1). This yields that the Cesàro means of a function f L1 converge a.e. to the function in question, provided that the Vilenkin system is bounded.     

Matrix Models from Operators and Topological Strings

We propose a new family of matrix models whose 1/N expansion captures the all-genus topological string on toric Calabi–Yau threefolds. These matrix models are constructed from the trace class operators appearing in the quantization of the corresponding mirror curves. The fact that they provide a non-perturbative realization of the (standard) topological string follows from a recent conjecture connecting the spectral properties of these operators, to the enumerative invariants of the underlying Calabi–Yau threefolds. We study in detail the resulting matrix models for some simple geometries, like local \({\mathbb{P}^2}\) and local \({\mathbb{F}_2}\), and we verify that their weak ’t Hooft coupling expansion reproduces the topological string free energies near the conifold singularity. These matrix models are formally similar to those appearing in the Fermi-gas formulation of Chern–Simons matter theories, and their 1/N expansion receives non-perturbative corrections determined by the Nekrasov–Shatashvili limit of the refined topological string.     

块对偶Toeplitz算子的乘积

本文刻画了向量值Bergman空间上块对偶Toeplitz算子有界性和紧性,给出了块对偶Toeplitz算子的乘积是块对偶Toeplitz算子的充要条件.     

Scattering Operators for Matrix Zakharov-Shabat Systems

In this article the scattering matrix pertaining to the defocusing matrix Zakharov-Shabat system on the line is related to the scattering operator arising from time-dependent scattering theory. Further, the scattering data allowing for a unique retrieval of the potential in the defocusing matrix Zakharov-Shabat system are characterized. The research leading to this article was supported in part by the Italian Ministery of Education and Research (MIUR) under PRIN grant no. 2006017542-003, and by INdAM. One of the authors (CvdM) wishes to express his gratitude for the hospitality of the Department of Mathematics of the University of Texas at Arlington during the Spring Semester of 2008 when part of the paper was written.     

Operator Matrix Forms of Positive Operators

If a 3-tuple (A:H1→H1,B:H2→H1,C:H2→H2）of operators on Hibert spaces is given,we proved that the operator ～↑A:=(↑A ↓B^*↑B ↓C) on H=H1 H2 is ≥0 is and only if A≥0,R(B)∪→R（A^1/2) and C≥B^* A^ b,where A^ is the generalized inverse of A.In general,A^ is a closed operator,but since R(B)∪→R(A^1/2,B^* A^ B is bounded yet.     

Sharp Weak Type Inequalities for Fractional Integral Operators

Suppose that d≥1 is an integer, α∈(0,d) is a fixed parameter and let I _α be the fractional integral operator associated with d-dimensional Walsh-Fourier series on (0,1] ^d . Let p, q be arbitrary numbers satisfying the conditions 1≤p<d/α and 1/q=1/p?α/d. We determine the optimal constant K, which depends on α, d and p, such that for any f∈L ^p ((0,1] ^d ) we have

$$ ||I_{\alpha } f||_{L^{q,\infty }((0,1]^{d})}\leq K||f||_{L^{p}((0,1]^{d})}. $$

In fact, we shall prove this inequality in the more general context of probability spaces equipped with a regular tree-like structures. This allows us to obtain this result also for non-integer dimension. The proof exploits a certain modification of the so-called Bellman function method and appropriate interpolation-type arguments. We also present a sharp weighted weak-type bound for I _α , which can be regarded as a version of the Muckenhoupt-Wheeden conjecture for fractional integral operators.

     

坡矩阵的积和式算子及若干不等式

引入坡矩阵积和式算子的概念．获得坡矩阵积和式算子关于偏序“≤”的若干不等式．     

分块初等方阵及其应用

本文我们先引入分块初等矩阵的概念，然后说明它的一些应用．     

On One Class of Matrix Differential Operators

We consider one class of matrix differential operators in the whole space. For this class of operators we establish the isomorphic properties in some special scales of weighted Sobolev spaces and study the regularity properties for solutions to the system of differential equations defined by these operators. The class of operators under consideration contains the stationary Navier–Stokes operator.     

缺项算子矩阵的谱

本文对缺项算子矩阵L=A&B ?&C的谱进行了一些深入的讨论,得出了∩X(LX)与∩X(LX)的表示,这里LX=A&B X&C.