理想收敛的若干研究及推广

在Banach空间X中利用序列的I-收敛与I*-收敛给出理想I具可加性质(AP)的等价刻画,并进一步研究弱I-收敛、弱I*-收敛、一致弱I*-收敛之间,以及弱I-收敛与收敛之间的关系,最后基于I-λ-统计收敛给出其推广:I-A-统计收敛,并以次微分映射为工具定义一族有限可加测度,用于等价刻画I-A-统计收敛,这亦是有限可加测度的一个应用体现.     

关于集值逆鞅的一些结果

证明了集值逆(上、下)鞅在Hausdorff收敛意义下的收敛定理,给出了集值逆鞅、逆上鞅在Kuratowski收敛意义下的收敛定理及集值逆下鞅在Kuratowski-Mosco收敛意义、弱收敛意义下的收敛定理。     

统计收敛与概率测度

早在1951年,H.F ast[6]就引入了统计收敛的定义.之后,出现了许多相关文章(如[4,7-14]等)对统计收敛做了进一步的探索与研究.自上世纪末本世纪初以来,统计收敛作为活跃的领域而得到了深入的研究.例如,统计收敛在数值理论[5],三角级数[15],强可和性[3],局部凸空间[10,13]以及局部紧空间中有界连续函数的理想结构[2]等领域中的讨论.本文通过引入μ-稠密收敛和μ-统计收敛的定义,对于给定一类概率测度U,证明了μ∈U,则序列μ-稠密收敛与统计收敛等价;对μ∈U,序列统计收敛必μ-统计收敛;μ∈U,序列都μ-统计收敛当且仅当序列统计收敛.     

几种收敛间的关系

归纳总结可测函数列关于一致收敛、近一致收敛、几乎处处收敛、依测度收敛等情况之间在一定前提条件下的关系,反例说明条件的变化将影响结论的正误,从而使收敛及其相互关系更为清晰和透彻.     

集值逆鞅的收敛性

研究集值逆鞅(集值逆上鞅)在Kuratowski收敛意义,Kuratowski-Mosco收敛意义及弱收敛意义下的收敛定理.     

加快迭代收敛速度的两个命题

定义了单调收敛函数和交错收敛函数,并根据其收敛特点,提出并证明了加快其收敛速度的两个命题.算例表明其效果较好.     

中国地区能源强度收敛性研究

基于1985-2010年中国29个地区的面板数据,对能源强度的收敛性进行了分析.在研究方法上,除了考察常见的β收敛和σ收敛外,还引入排名一致性系数对γ收敛进行了检验.研究结果表明,中国地区能源强度存在显著的β收敛和γ收敛;对于σ收敛,在采用变异系数法进行检验时,并未反映出显著的σ收敛特征,但采用核密度估计则较好的验证了我国地区能源强度的σ收敛性.     

实变函数课程教学中的反例应用

通过构造反例,辅助说明一致收敛和几乎处处收敛、依测度收敛和几乎处处收敛、可测函数和连续函数等概念间的关系,以加深学生对相关知识的理解.     

Fourier级数两个收敛定理的关系及反例

Fourier级数的收敛问题一直是很多数学研究者关注的问题,不同的数学分析教材和高等数学教材对收敛定理的表述各不相同。本文通过实例说明这些收敛定理之间不存在包含关系,并进一步说明这些收敛定理都是判别Fourier级数收敛的充分条件,而不是充要条件。     

关于可测函数列各种收敛性的几点注记

关于可测函数列的收敛性，除了众所周知的处处收敛、一致收敛、几乎处处收敛外，尚有依测度收敛、平均收敛和弱收敛等．本文将主要讨论它们之间的相互关系．     

The inviscid limit for the complex Ginzburg-Landau equation

We study the inviscid limit of the complex Ginzburg-Landau equation. We observe that the solutions for the complex Ginzburg-Landau equation converge to the corresponding solutions for the nonlinear Schrödinger equation. We give its convergence rate. We estimate the integral forms of solutions for two equations.     

Uniform convexity and the splitting problem for selections

We continue to investigate cases when the Repovš–Semenov splitting problem for selections has an affirmative solution for continuous set-valued mappings. We consider the situation in infinite-dimensional uniformly convex Banach spaces. We use the notion of Polyak of uniform convexity and modulus of uniform convexity for arbitrary convex sets (not necessary balls). We study general geometric properties of uniformly convex sets. We also obtain an affirmative solution of the splitting problem for selections of certain set-valued mappings with uniformly convex images.     

Economical Iterative Algorithms for Solving Stationary Problems of Mathematical Physics

We construct and investigate additive iterative methods of complete approximation for solving stationary problems of mathematical physics. We prove the convergence of the proposed methods and obtain error estimates without the requirement of commutativity of the decomposition operators. We provide the results of a computational experiment for a three-dimensional boundary-value problem. We consider possible generalizations of algorithms for equations with mixed derivatives and Navier–Stokes equation systems.     

Stochastic center of systems of stochastic differential equations on the plane

We study a stochastic analogy of the famous center problem of Dulac for quadratic differential equations in the plane. We introduce the concept of center for systems of stochastic differential equations of It\^o''s type on the plane, called stochastic center. We derive a criterion for the existence of such a center. We apply it to obtain necessary and sufficient conditions for quadratic stochastic differential equations in dimension 2.     

Bounds and Characterizations of Authentication/Secrecy Schemes

We consider authentication/secrecy schemes from the information theoretic approach. We extend results on unconditionally secure authentication schemes and then consider unconditionally secure authentication schemes that offer perfect L-fold secrecy. We consider both ordered and unordered secrecy. We establish entropy bounds on the encoding rules for authentication schemes with these types of secrecy. We provide some combinatorial characterizations and constructions for authentication schemes having perfect L-fold secrecy that meet these bounds.     

Blow-up solutions of cubic differential systems

We investigate the existence problem for blow-up solutions of cubic differential systems. We find sets of initial values of the blow-up solutions. We also discuss a method of finding upper estimates for the blow-up time of these solutions. Our approach can be applied to systems of partial differential equations. We apply this approach to the Cauchy-Dirichlet problem for systems of semilinear heat equations with cubic nonlinearities.     

Periodic non-autonomous second-order dynamical systems

We study the existence of periodic solutions for a second-order non-autonomous dynamical system. We give three sets of hypotheses which guarantee the existence of non-constant solutions. We were able to weaken the hypotheses considerably from those used previously for such systems. We employ a saddle point theorem using linking methods.     

On vector formulations of auction-type problems with applications

We propose an extension of the auction model with many divisible commodities for vector price (validity) functions. It can be viewed as a new general equilibrium model for complex systems with active elements. We give its sufficient vector variational inequality formulation and new general existence results for different ordering cones. We suggest vector extensions of network and spatial equilibrium problems with capacity bounds and show that they are particular cases of the general auction model. We also give new sufficient conditions for existence of solutions for these problems.     

Supersymmetry, Witten Complex and Asymptotics for Directional Lyapunov Exponents in Zd

. We study the long distance asymptotic for random walks in random potentials. We use the analytical formulation. We relate the problem to Witten Laplacians via using supersymmetry. We obtain the asymptotic for the directional Lyapunov exponents.     

APPROXIMATE DUALITY OF g-FRAMES IN HILBERT SPACES

In this article, we introduce and characterize approximate duality for g-frames. We get some important properties and applications of approximate duals. We also obtain some new results in approximate duality of frames, and generalize some of the known results in approximate duality of frames to g-frames. We also get some results for fusion frames, and perturbation of approximately dual g-frames. We show that approximate duals are stable under small perturbations and they are useful for erasures and reconstruction.