Structure and BIBO stability of a three-dimensional fuzzy two-term control system

A novel three-dimensional fuzzy logic controller (3D FLC) was developed recently for spatially distributed systems. In this study, the inherent spatial structure feature of a 3D FLC with two spatial inputs (also called as 3D two-term FLC) is first exposed via an analytical model. Then, the global bounded-input/bounded-output (BIBO) stability of the 3D fuzzy two-term control system is discussed. A sufficient condition is derived and provided as a useful criterion for the controller design of the 3D two-term FLC. Finally, a catalytic packed-bed reactor is presented as an example of spatially distributed process to demonstrate the effectiveness of the controller.     

Transient model of induction machine using rotating magnetic field approach

Most simulation models of electric machines use the coupled circuit approach, where the machine is considered as an electric circuit element with time-varying inductances (abc model) or with constant inductances (dq0 model). On the other hand, the rotating magnetic field approach, which considers the electric machine as two groups of windings producing rotating magnetic fields and can give insight into internal phenomena of the machines, has not yet received much attention in electric machines modeling, especially for machine transient analysis. Based on the rotating magnetic field approach, this paper presents a transient model of the induction machine including main flux saturation effect. Based on the direct computation of the magnetizing fluxes of all machine windings, the model represents instantaneous main flux saturation by simply introducing a main flux saturation factor. No iteration process is involved to incorporate the saturation effects. The model combines the advantages of the dq0 and abc models advantages, such as rapid computation time and nonsymmetrical conditions simulation, respectively. The simulation results and the experimental tests show advantages and verification of the model.     

User goals in social virtual worlds: A means-end chain approach

The purpose of this study is twofold: first, to investigate user goals in social virtual worlds; second, to introduce a methodological alternative (i.e., a means-end chain approach) for analyzing user goals in cyberspaces. The data were acquired from a web survey, and were analyzed by means-end chain analysis (MECA), which produces users’ goal structure in reference to a hierarchical system of interrelated goals (Olson & Reynolds, 1983). The results show that people come to social virtual worlds to satisfy their social and hedonic needs, and to escape from real world constraints, as do virtual community members and virtual gamers; they also pursue unique activities, such as creating virtual objects and selling them. On the other hand, by clarifying relations among users’ goals, MECA provides a richer explanation for user goals than prior research which only offers separate user goals for cyberspace users without explanation of relationship among goals.     

Towards a web-based progressive handwriting recognition environment for mathematical problem solving

The emergence of pen-based mobile devices such as PDAs and tablet PCs provides a new way to input mathematical expressions to computer by using handwriting which is much more natural and efficient for entering mathematics. This paper proposes a web-based handwriting mathematics system, called WebMath, for supporting mathematical problem solving. The proposed WebMath system is based on client–server architecture. It comprises four major components: a standard web server, handwriting mathematical expression editor, computation engine and web browser with Ajax-based communicator. The handwriting mathematical expression editor adopts a progressive recognition approach for dynamic recognition of handwritten mathematical expressions. The computation engine supports mathematical functions such as algebraic simplification and factorization, and integration and differentiation. The web browser provides a user-friendly interface for accessing the system using advanced Ajax-based communication. In this paper, we describe the different components of the WebMath system and its performance analysis.     

非安全协议脆弱性的混合分析方法

针对手动方法对非安全协议分析过程中存在的不足,提出一种用于非安全协议的混合分析方法,并在手动分析的基础上,应用形式化自动工具分析协议的脆弱性。通过将该方法应用到移动IPv6协议,发现了新的脆弱性问题。仿真实验结果表明,该方法适合分析非安全协议,能够检查协议设计中的细微脆弱性问题,具有一定的系统性和较好的完备性。     

2009年下半年网络规划设计师考试分析

网络规划设计师考试属于全国软件水平考试中高级级别的考试。该文根据2009年11月网络规划设计师考试试题的情况,分析了考试的难点和重点。     

基于SSH架构的高职院校成绩管理系统的分析和设计

本文介绍了当前基于Struts2、Spring、Hibernate框架的高职院校成绩管理系统的分析和设计。     

Robust MIMO disturbance observer analysis and design with application to active car steering

A multi‐input–multi‐output extension of the well‐known two control degrees‐of‐freedom disturbance observer architecture that decouples the problem into single‐input–single‐output disturbance observer loops is presented in this paper. Robust design based on mapping D‐stability and the frequency domain specifications of weighted sensitivity minimization and phase margin bound to a chosen controller parameter space is presented as a part of the proposed design approach. The effect of the choice of disturbance observer Q filter on performance is explained with a numerical example. This is followed by the use of structured singular values in the robustness analysis of disturbance observer controlled systems subject to structured, real parametric and mixed uncertainty in the plant. A design and simulation study based on a four wheel active car steering control example is used to illustrate the methods presented in the paper. Copyright © 2009 John Wiley & Sons, Ltd.     

Multiple robust H∞ controller design using the nonsmooth optimization method

This paper proposes a systematic technique to design multiple robust H_∞ controllers. The proposed technique achieves a desired robust performance objective, which is impossible to achieve with a single robust controller, by dividing the uncertainty set into several subsets and by designing a robust controller to each subset. To achieve this goal with a small number of divisions of the uncertainty set, an optimization problem is formulated. Since the cost function of this optimization problem is not a smooth function, a numerical nonsmooth optimization algorithm is proposed to solve this problem. This method avoids the use of Lyapunov variables, and therefore it leads to a moderate size optimization problem. A numerical example shows that the proposed multiple robust control method can improve the closed‐loop performance when a single robust controller cannot achieve satisfactory performance. Copyright © 2009 John Wiley & Sons, Ltd.     

社保网络信息安全防护

本文针对各种威胁社保网络安全的多种因素,进行有的放矢地构建相应策略,综合立体地进行网络安全防护,构建了一个多方面考虑的安全网络,这样社保部门在保护计算机网络设备安全和计算机网络系统安全的同时也保护了数据的安全,为构建和谐社会贡献力量。