一种基于Linux嵌入式系统的防火墙的开发

介绍了一种基于Linux嵌入式系统的防火墙解决方案。文章首先简要介绍了嵌入式系统的特点,然后分析Linux内核中的防火墙实现方法,然后介绍该防火墙系统的硬件和软件结构,并详细阐述了该防火墙系统中的软件实现。     

基于单片机的USB传输系统的设计与实现

本文介绍了一种基于SL8111HS芯片及单片机的USB传输系统;系统由单片机、USB接口控制器、高速RAM、串口等设备组成;首先分析了USB系统的通信协议,然后介绍系统的硬件设计,最后介绍系统的软件实现过程。     

基于计算机网络管理的高速公路上收费系统的建立

本文首先介绍我国联网收费所面临的问题提出实施"高速公路上收费系统网络架构"的必要性,然后具体介绍高速公路上收费系统网络的架构,详细介绍高速公路上收费系统网络的系统功能设计,介绍路网智能化收费系统的应用情况,包括取得的成绩和效益.     

脉冲发电机组计算机控制系统的研究

介绍了一种脉冲发电机组的计算机控制系统, 介绍了该系统的励磁控制系统、模式识别系统和工业控制网络, 介绍了该系统的软、硬件设计以及控制系统特点。     

GPS车辆追踪系统的实现

依据珠海１２０系统的实际研制、开发,介绍了ＧＰＳ系统在汽车监控领域的一种应用──车辆自动追踪系统,重点介绍了系统的整体结构、系统原理、系统功能、系统的优点及系统的技术指标。     

基于ARM的RFID阅读器设计

本文给出了基于ARM微处理器的RFID阅读器设计方案。文章介绍了RFID概念、发展现状及系统组成;介绍了系统的硬件组成模块,讨论两款主要芯片的功能,给出系统总体设计和各模块功能说明;介绍了系统的软件组成模块,并给出模块说明及模块流程图;详细介绍了一种改进的防碰撞算法;最后,总结并展望了本系统。     

仿生系统：一种进化仿真框架的简介

文章主要介绍了一种进化仿真框架——仿生系统SimBioSys,首先介绍了这种仿生系统的概念,其次通过介绍它的类关系和定义揭示了它的静态结构,最后提出这种仿生系统的动态循环结构,并简单介绍了仿生系统在科学研究中的应用。     

基于PLC的水泥磨控制系统的设计

文章介绍了一种基于PLC的水泥磨控制系统,详细介绍了该系统的硬件组成,给出了系统硬件和软件设计。实际应用表明,该系统操作灵活,运行安全可靠。     

点焊机器人系统在一汽轿车生产线上的应用及经验

本文介绍点焊机器人系统在汽车生产中的应用,着重介绍点焊机器人系统的构成和控制方式,详尽介绍点焊机器人系统的应用经验,同时结合作者亲身经历,总结点焊机器人系统在使用过程中的注意事项。     

基于FPGA的QPSK高速数字调制系统的研究与实现

介绍了一种基于FPGA的QPSK高速数字调制系统的实现方案。先从调制系统的基本框图入手,简要介绍其实现原理及流程;然后着重介绍FPGA功能模块的软件编程、优化及整个系统的性能。     

针对同步时序电路VHDL设计的有效模型判别器VERIS

介绍了一个针对同步时序电路VHDL设计的性质验证的解决方案-一个有效的符号模型判别器VERIS,该模型判别器利用同步时序电路设计的特点以及待验证性质的局部性,可显著地减少有限状态机（FSM）的状态空间;大大地提高可达性分析和性质验证的速度;同时,实现了反例生成机制,实验结果表明,与Deharbe的模型判别器相比,用这个模型判别器验证一些基准电路更加适用于同步时序电路。     

一个经过证明的类型化汇编语言的类型检查器

编程语言类型系统的类型安全性可以保证程序运行时满足基本安全属性,包括控制流安全, 内存安全等.类型化编程语言都需要一个类型检查器来检查程序的良类型性,因此编程语言的具体实现是否能保证类型安全性,还依赖类型检查器的可靠性.本文给出一种类型化汇编语言,然后给出相应的类型检查器,并证明了此类型检查器的可靠性,从而保证经过类型检查的汇编程序的安全性.文本的所有工作,包括类型化汇编语言、类型检查器以及相关定理证明,均已在证明辅助工具Coq中实现.本文方法也可用于证明类型化高级语言的类型检查器的可靠性.     

Designing and developing a language environment for second language writers

This paper presents a field study carried out with learners who used a grammar checker in real writing tasks in an advanced course at a Swedish university. The objective of the study was to investigate how students made use of the grammar checker in their writing while learning Swedish as a second language. Sixteen students with different linguistic and cultural backgrounds participated in the study. A judgment procedure was conducted by the learners on the alarms from the grammar checker. The students’ texts were also collected in two versions; a version written before the session with the grammar checker, and a version after the session. This procedure made it possible to study to what extent the students followed the advice from the grammar checker, and how this was related to their judgments of its behavior.The results obtained demonstrated that although most of the alarms from the grammar checker were accurate, some alarms were very hard for the students to judge correctly. The results also showed that providing the student with feedback on different aspects of their target language use; not only on their errors, and facilitating the processes of language exploration and reflection are important processes to be supported in second-language learning environments.Based on these results, design principles were identified and integrated in the development of Grim, an interactive language-learning program for Swedish. We present the design of Grim, which is grounded in visualization of grammatical categories and examples of language use, providing tools for both focus on linguistic code features and language comprehension.     

Designing and developing a language environment for second language writers

This paper presents a field study carried out with learners who used a grammar checker in real writing tasks in an advanced course at a Swedish university. The objective of the study was to investigate how students made use of the grammar checker in their writing while learning Swedish as a second language. Sixteen students with different linguistic and cultural backgrounds participated in the study. A judgment procedure was conducted by the learners on the alarms from the grammar checker. The students’ texts were also collected in two versions; a version written before the session with the grammar checker, and a version after the session. This procedure made it possible to study to what extent the students followed the advice from the grammar checker, and how this was related to their judgments of its behavior.The results obtained demonstrated that although most of the alarms from the grammar checker were accurate, some alarms were very hard for the students to judge correctly. The results also showed that providing the student with feedback on different aspects of their target language use; not only on their errors, and facilitating the processes of language exploration and reflection are important processes to be supported in second-language learning environments.Based on these results, design principles were identified and integrated in the development of Grim, an interactive language-learning program for Swedish. We present the design of Grim, which is grounded in visualization of grammatical categories and examples of language use, providing tools for both focus on linguistic code features and language comprehension.     

A model checker for linear time temporal logic

This report describes the design and implementation of a model checker for linear time temporal logic. The model checker uses a depth-first search algorithm that attempts to find a minimal satisfying model and uses as little space as possible during the checking procedure. The depth-first nature of the algorithm enables the model checker to be used where space is at a premium.This work was supported both by Alvey under grant PRJ/SE/054 (SERC grant GR/D/57942) and by ESPRIT under Basic Research Action 3096 (SPEC).     

Automated analysis of timed security: a case study on web privacy

This paper presents a case study on an automated analysis of real-time security models. The case study on a web system (originally proposed by Felten and Schneider) is presented that shows a timing attack on the privacy of browser users. Three different approaches are followed: LH-Timed Automata (analyzed using the model checker HyTech), finite-state automata (analyzed using the model checker NuSMV), and process algebras (analyzed using the model checker CWB-NC ). A comparative analysis of these three approaches is given.     

Tool support for verifying UML activity diagrams

We describe a tool that supports verification of workflow models specified in UML activity diagrams. The tool translates an activity diagram into an input format for a model checker according to a mathematical semantics. With the model checker, arbitrary propositional requirements can be checked against the input model. If a requirement fails to hold, an error trace is returned by the model checker, which our tool presents by highlighting a corresponding path in the activity diagram. We summarize our formal semantics, discuss the techniques used to reduce an infinite state space to a finite one, and motivate the need for strong fairness constraints to obtain realistic results. We define requirement-preserving rules for state space reduction. Finally, we illustrate the whole approach with a few example verifications.     

Improving Web site design

Using quantitative measures of the informational, navigational, and graphical aspects of a Web site, a quality checker aims to help nonprofessional designers improve their Web sites. As part of the WebTango project, we explore automated approaches for helping designers improve their sites. Our goal is to create an interactive tool that helps steer occasional Web site builders away from bad designs and toward better ones - a "quality checker" tool, analogous to a grammar checker in a word processor. What distinguishes our work from most others is that this tool is based on empirically derived measures computed over thousands of Web pages. We converted these measures, which characterize the informational, navigational, and graphical aspects of a Web site, into profiles for a variety of site types. Our rudimentary design-checking tool uses these profiles to assess Web site designs; future versions will also suggest design improvements     

Checking the correctness of memories

We extend the notion of program checking to include programs which alter their environment. In particular, we consider programs which store and retrieve data from memory. The model we consider allows the checker a small amount of reliable memory. The checker is presented with a sequence of requests (on-line) to a data structure which must reside in a large but unreliable memory. We view the data structure as being controlled by an adversary. We want the checker to perform each operation in the input sequence using its reliable memory and the unreliable data structure so that any error in the operation of the structure will be detected by the checker with high probability.We present checkers for various data structures. We prove lower bounds of logn on the amount of reliable memory needed by these checkers wheren is the size of the structure. The lower bounds are information theoretic and apply under various assumptions. We also show time-space tradeoffs for checking random access memories as a generalization of those for coherent functions.This work was supported in part by NSF Grant CCR 88-13632. A preliminary version of this paper appeared at the 32nd IEEE Symposium on Foundations of Computer Science [2].