一类具有logistic源的高维Keller-Segel模型的爆破

本文考虑如下带有logistic源的Keller-Segel模型的Cauchy问题：■其中χ>0,λ≥0,μ≥0,k>1,证得当n≥5时若■则问题解在有限时间爆破.这表明在高维情况下即便有logistic源的存在也不能排除爆破的发生.     

Specification and Verification for Semi-Structured Data

Tree logic, inherited from ambient logic, is introduced as the formal foundation of related programming language and type systems, In this paper, we introduce recursion into such logic system, which can describe the tree data more dearly and concisely. By making a distinction between proposition and predicate, a concise semantics interpretation for our modal logic is given. We also develop a model checking algorithm for the logic without △ operator. The correctness of the algorithm is shown. Such work can be seen as the basis of the semi-structured data processing language and more flexible type system.     

A heuristic algorithm to solve the task partition problem in MDOCEM

This paper examines task partition problem in a Multiagent-based Distributed Open Computing Environment Model (MDOCEM). We first present a formal method to describe the task partition problem, then give a heuristic algorithm to solve the task partition problem that gives an approximate optimum solution. Foundation item: Supported partially by the National 863 High Technology Project (863-306-05-01-1B) Biography: He Yan-xiang (1952-), male, Professor, Research interests include distributed OS and distributed information processing, distributed software engineering, parallel compiler.     

Design and Implementation of FAQ Automatic Return System Based on Similarity Computation

FAQ （frequently asked question） is widely used on the Internet, but most FAQ＇s asking and answering are not automatic. This paper introduces the design and imple mentation of a FAQ automatic return system based on semantic similarity computation, including computation model choo sing, FAQ characters analyzing, FAQ data formal expressing, feature vector indexing, and weight computing and so on. According to FAQ features of sentence length short, two mapping, strong domain characteristics etc. Vector Space Model with special semantic process was selected in system, and corresponding algorithm of similarity computation was proposed too. Experiment shows that the system has a good performance for high frequent and common questions.     

中介命题系统MP推理规则的简化

对中介逻辑命题演算系统MP的18条推理规则作了简化,从中删除了5条不独立的推理规则,构成与原推规则集S等价的形式推理规则集S1。     

Towards the Idealization Procedure of BAN-Like Logics

We demonstrate the flaws of Mao‘s method, which is an augmentation of protocol idealization in BAN-like logics, and then offer some new idealization rules based on Mao‘s method. Furthermore, we give some theoretical analysis of our rules using the strand space formalism, and show the soundness of our idealization rules under strand spaces. Some examples on using the new rules to analyze security protocols are also concerned. Our idealization method is more effective than Mao‘s method towards many protocol instances, and is supported by a formal model.     

Global Existence and Decay of Solution to Parabolic-Parabolic Keller-Segel Model in Rd

We consider the global existence and decay of integral solutions to the parabolic-parabolic Keller-Segel system in d-dimension. On the one hand, by Banach fixed...     

The Reliability Design and Availability Analysis of a Distributed Storage System

Current distributed parallel file systems and database systems can not satisfy the demands of data-intensive applications, such as storage capacity, access performance, reliability, scalability, and so on. Cluster-based storage sys tems have some shortcomings, too. To solve this kind of problems, a novel PC storage cluster solution is proposed, a distributed storage system based on 3-tiered agent architecture is designed, the system reliability model based on the masterslave backup mode is built, and the system availability is analyzed with the Markov model. According to the system availability formula and the values of the system parameters, the novel system can provide higher reliability and availability to satisfy users＇ requirements,     

Specifying requirements of real-time system with rules and templates

This paper presents a model specifying requirements of real-time systems. Different from existing researches, this model mainly uses rules and templates to represent hierarchical FSMs (Finite State Machine). In this model, one rule corresponds to one state transition of FSM and one template corresponds to one FSM. Rules and information with respect to a FSM can be written in a template. So templates include not only state diagrams, but also information that can not be described by FSM, such as performance requirements. The specification using this model consists of a collection of templates and it is easy for users to understand and to review. After introduced the related researches and principles of the model, this paper specifies requirements of a real-time system with this model, and discusses characters of this model in the end. Foundation item: Supported by the National Natural Science Foundation of China (69873035) and the Research Fund for the Doctoral Program of Higher Education(RFDP) Biography: Wu Guo-qing(1954-), male, Professor, research interest: software formal theory, requirement engineering.     

Describing Service-Oriented Architecture by Extended Darwin

Describing Service-Oriented Architecture （SOA） is critical in the development of Web based system, in this paper, an approach for describing SOA by extended Darwin is proposed. The requirements for describing SOA, which are different from that of ordinary architecture, are highlighted firstly, and then a solution for extending Darwin is presented. Using the extended Darwin, service components and connectors can be described explicit by the extended construct, as well as precise operational semantics of SOA by the π-calculus. Finally an example of supply-chain management system is given for manifesting the effect of the extended Darwin.     

An effective novel reaction system for the photo-degradation of aqueous organic pollutants

A novel reaction system consisted of a supported TiO₂ film electrode, a Ru−Ti oxide film electrode and air (oxygen) electrode is reported. The air (oxygen) electrode can provide H₂O₂ continuously for homogeneous photochemical oxidation reaction on the spot. In this reactor, degradation reaction of aniline occur from interface of TiO₂ film to all solution which is irradiated by ultraviolet ray. The degradation rate of aniline was characterized by measuring the change of chemical oxygen demand (COD) in solution under different conditions. It was found that the degradation rate of aniline in the novel system increased apparently as compared with single heterogeneous photocatalysis and homogeneous photochemistry system. It can be explained in terms of combining acts of heterogeneous photocatalysis and homogeneous photochemistry. Foundation item: Supported by the National Natural Science Foundation of China (10791033) Biography: CAI Nai-cai (1946-), male, Associate professor, Research direction: electrochemical catalysis and photocatalysis.     

A Robust IP Packets Filtering Mechanism for Protecting Web Server from DDoS Attacks

Distributed denial of service （DDoS） attacks exploit the availability of Web servers, resulting in the severe loss of their connectivity. We present a robust IP packets filtering mechanism which combines the detection and filtering engine together to protect Web Servers from DDoS Attacks. The mechanism can detect DDoS attacks by inspecting inbound packets with an IP address database, and filter out lower priority IP addresses to preserve the connection for valid users by monitoring the queues status. We use the Netfilter＇s technique, a framework inside the Linux 2.4. X, to implement it on a Web server. Also, we evaluate this mechanism and analyze the influence of some important parameters on system performance. The experimental results show that this mechanism is effective against DDoS attacks.     

Remote intelligent identification system of structural damage

The focus of this paper is to build the damage identify system, which performs “system identification“ to detcct the positions and extents of structural damages. The identification of structural damage can be characterized as a nonlinear process which linear prediction models such as linear regression are not suitable. However. neural network techniques may provide an effective tool for system identification. The method of damage identification using the radial basis function neural network (P, BFNN) is presented in this paper. Using this method, a simple reinforced concrete structure has been tested both in the absence and presence of noise. The resuits show that the RBFNN identification technology can he used with related success for the solution of dynamic damage identification problems, even in the presence of a noisy identify data. Furthermore, a remote identification system based on that is set up with Java Technologies.     

On the approximation solvability of the abstract differential inclusion

The approximation solvability of the abstract differential inclusion du/dt∈f(t,u) is presented. The convergence of the approximation solution and the existence of the solution for abstract evolution multivalued problem are discussed. Foundation item: Supported by the National Natural Science Foundation of China (No. 19771062) Biography: Xia Jin-sheng (1975-), Ph.D candidate, research interest: the approximate solution of differential equation.     

A generalized Riemann boundary value problem

The generalized Riemann boundary value problem for analytic functions is considered, where the unknown function may have branch points of the second order. Under certain assumptions, its general solution as well as the condition of solvability is obtained when the solution is required to be of finite order at infinity. Foundation item: Supported by the National Natural Science Foundation of China (No. 19871064) Biography: LIU Hua(1971-), male, Ph. D candidate, Research interests being in complex analysis and its applications.     

偏好、强序刻画和社会选择形式空间等价

为研究一般社会选择函数的构造机制,该文通过一般性偏好的运算形成偏好的强序刻画,并基于此证明在形式背景下社会选择函数全空间的一些等价性和自等价性.但是在强序刻画下,社会选择函数的存在性定理(Arrow定理)的构造相对简化,约束公理系统的配置也简化,这为全面形式化处理Arrow定理提供了有力工具.     

An improved moving mesh algorithm

We consider an iterative algorithm of mesh optimization for finite element solution, and give an improved moving mesh strategy that reduces rapidly the complexity and cost of solving variational problems. A numerical result is presented for a 2-dimensional problem by the improved algorithm. Foundation item: Supported by the National Natural Science Foundation of China(No. 19771062) Biography: Cheng Jian(1977-), male, Master candidate, research interests: the numerical solution of PDE.     

One method for improving RAID5 performance

As a kind of parallel storage system, RAID5 has been becoming a popular solution for providing better performance at low cost and without sacrificing much redundant data, its main disadvantage is poor performance. It is a general method to improve RAID5 performance by using cache. However, it often happens that the data is not hit in cache, in this case, the RAID5 performance also will be very poor. The method based on combination of disk I/O operations has been proposed for impriving the I/O response time through reducing the number of low-level operations. According to theoretic analysis and experimental test, we find that RAID5 access time and data transfer rate could be largely improved than conventional method. Foundation item: Supported by the National Natural Science Foundation of China under grant 69773046 and (69973017), and Defense Advanced Research Foundation of China under grant (98J15. 1. 1. JW0516) Biography, Chen Qiong (1963-), female, Ph. D candidate, research interests: computer architecture, parallel processing, disk arrays.     

The Configuration Strategies on Caching for Web Servers

The Web cluster has been a popular solution of network server system because of its scalability and cost effective ness. The cache configured in servers can result in increasing significantly performance, In this paper, we discuss the suitable configuration strategies for caching dynamic content by our experimental results. Considering the system itself can provide support for caching static Web page, such as computer memory cache and disk＇s own cache, we adopt a special pattern that only caches dynamic Web page in some experiments to enlarge cache space. The paper is introduced three different replacement algorithms in our cache proxy module to test the practical effects of caching dynamic pages under different conditions. The paper is chiefly analyzed the influences of generated time and accessed frequency on caching dynamic Web pages. The paper is also provided the detailed experiment results and main conclusions in the paper.     

A formula of solution for a class of homogeneous recurrence of variable coefficients with two indices

In this paper, we obtain an explicit formula of general solution for a class of the homogeneous recurrence of variable coefficients with two indices. Foundation item: Supported by the National Natural Science Foundation of China(19771063) Biography: YU Chang-an(1948-), male, Professor, Current research interest is in combinatorial theory