Louis H．Y．Chen定理的推广

ＬｏｕｔｓＨ．Ｙ．Ｃｈｅｎ在文［１］中应用测度论的方法，证明标准正态随机向量的一个充分条件．本文指出它也是必要条件．同时将它推广到一般多元正态分布的情形，从而得到几个一般性结论．     

Integrating Multi-Source Web Records into Relational Database

How to integrate heterogeneous semi-structured Web records into relational database is an important and challengeable research topic. An improved model of conditional random fields was presented to combine the learning of labeled samples and unlabeled database records in order to reduce the dependence on tediously hand-labeled training data. The pro- posed model was used to solve the problem of schema matching between data source schema and database schema. Experimental results using a large number of Web pages from diverse domains show the novel approach＇s effectiveness.     

Protein folding revisited. A polypeptide chain at the folding – misfolding – nonfolding cross-roads: which way to go?

The structure-function paradigm claims that a specific function of a protein is determined by its unique and rigid three-dimensional (3D) structure. Thus, following its biosynthesis on the ribosome, a protein must fold to be functional. This idea represents one of the cornerstones of modern biology. Numerous cases when, due to the effect of environmental factors or because of genetic defects (mutations), a polypeptide chain has lost its capability to gain a proper functional 3D structure (i.e. became misfolded), seem to confirm this concept. Consequences of such misfolding are well known and represent lost of function, aggregation, development of conformational disorders and cell death. However, the recent revelation of countless examples of intrinsically disordered proteins has cast doubt on the general validity of the structure-function paradigm and revealed an intriguing route of functional disorder. Thus, in a living cell, a polypeptide chain chooses between three potential fates – functional folding, potentially deadly misfolding and mysterious nonfolding. This choice is dictated by the peculiarities of amino acid sequence and/or by the pressure of environmental factors. The aim of the present review is to outline some interesting features of these three routes.Received 5 March 2003; received after revision 28 March 2003; accepted 31 March 2003     

Internet网上汉字与图形E-mail的解读、编存与传送

分析了用Internet传送汉字与图形E-mail时的"乱码"问题.介绍了汉字与图形电子邮件的解读、编写、存储及传送的方法.     

循环平稳性与随机共振理论的非绝热描述

噪声背景中周期信号的循环平稳性是信号处理中一个重要的特征.本文利用随机循环平稳过程的有关理论研究复杂随机动态系统中的随机共振现象.依据系统输出的一维准稳态概率密度近似理论,本文推导了系统输出二维跃迁概率密度、稳态自相关函数和系统输出信噪比的公式.输出信噪比随着输入噪声强度增加而呈现的随机共振现象,理论分析和数值试验结果非常吻合.此理论为随机共振理论的一种非绝热描述,不仅能够解释经典随机共振现象,而且能够描述驻留随机共振现象,对于复杂随机动态系统的信息处理机制具有重要理论指导意义.     

一种K分布随机数产生方法

Abraham（2002）从海底散射的物理现象出发。提出并证明了有限个幅度服从指数分布，相位服从均匀分布的复随机变量之和的模服从K分布．本文以Abraham的上述理论为基础构造了一种K分布随机数产生方法．该方法以一组相互独立。在区间[0，1]服从均匀分布随机数为基础，经过一系列运算，即可产生服从K分布的随机数．还对该方法进行了仿真分析，结果表明该方法可以有效地产生K分布随机数，而且比较简单，易于实现。     

元胞蚂蚁算法的收敛性分析

提出一种新的优化算法，元胞蚂蚁算法，该算法将元胞自动机的邻居和规则引入传统的蚂蚁算法，实验结果证明该算法可行且有效，有良好的全局优化能力。定义元胞蚂蚁算法的求解迭代过程为一个概率测度空间中的随机算子，利用随机不动点理论，证明了该算子为连续压缩算子，存在唯一的随机不动点，从而给出了元胞蚂蚁算法的收敛性的论证，为算法奠定了相应的理论基础。     

一种基于FFT的高动态GPS信号快速捕获方法

对高动态GPS信号快速捕获问题进行了研究,提出了一种适应高动态环境,捕获时间短的捕获方法。该方法采用多普勒频域串行捕获,时域由FFT代替滑动相关的并行捕获的二维策略,从而大大提高了高动态GPS接收机的信号捕获性能。分析了基于FFT的快速捕获原理和软件实现,并通过对实测的GPS信号的捕获验证了该捕获方法的正确性。     

基于三维混沌猫映射图像加密算法的改进

针对基于三维混沌猫映射的图像钥加密算法,提出了一种有效的改进算法。该算法使用随机扫描进行加密预处理,并在扩散过程和密钥产生器中分别使用双密钥和组密钥的方式,而且采用混沌物理量进一步衡量该加密系统的性能。仿真结果表明,该方法具有高置乱程度、良好的扩散性能和足够大的密钥空间,可获得足够高的安全性,不仅能抵抗差分攻击、选择明文攻击、统计攻击等,而且取得了复杂度和速度的良好折中,适合应用于实时的按安全级别加密的网络图像加密中。     

The Classification of States for Markov Chain in Random Environments and m-irreducible

First of all,we introduces the concept of m-irreducible of Markov chain in random environment. Then under the condition of m-irreducible,the relationship of recurrent and positive recurrent between two states is studied. We also give several conditions that can imply a state is recurrent and positive recurrent. And then the period of a state is discussed and we obtained that under the condition of m-irreducible,for any two states in X ,they have the same period.