Development of a web-based system for engineering change management

Engineering changes (ECs) are changes and/or modifications in forms, fits, functions, materials, dimensions, etc., of products and constituent components. ECs usually induce a series of downstream changes. Multiple disciplines and responsibilities are therefore involved in managing ECs. Previous investigations conducted by the authors and other researchers have shown that paper-based and standalone computerised EC management (ECM) systems have limited support for such intensive teamwork and close communication. This paper proposes to establish a web-based framework that supports ECM procedures and activities. A web-based ECM system is able to provide better information sharing, simultaneous data access and processing and more prompt communication and feedback. The amount of paperwork and the throughput time of managing ECs are significantly reduced while the effectiveness and the efficiency are substantially improved. This paper focuses on discussing the issues of design, development, and implementation of this prototype web-based ECM system.     

Presheaves as Configured Specifications

The paper addresses a notion of configuring systems, constructing them from specified component parts with specified sharing. This notion is independent of any underlying specification language and has been abstractly identified with the taking of colimits in category theory. Mathematically it is known that these can be expressed by presheaves and the present paper applies this idea to configuration. We interpret the category theory informally as follows. Suppose ? is a category whose objects are interpreted as specifications, and for which each morphism u : X→Y is interpreted as contravariant ‘instance reduction’, reducing instances of specification Y to instances of X. Then a presheaf P: Set ^?op represents a collection of instances that is closed under reduction. We develop an algebraic account of presheaves in which we present configurations by generators (for components) and relations (for shared reducts), and we outline a proposed configuration language based on the techniques. Oriat uses diagrams to express colimits of specifications, and we show that Oriat's category Diag(?) of finite diagrams is equivalent to the category of finitely presented presheaves over ?. Received May 1998 / Accepted in revised form August 2000     

基于VB的模型组态仿真软件的技术研究

介绍了利用Visual Basic开发对象模型组态仿真软件的一些技术,主要包括用户界面的建立、创建并调用ActiveX控制实现I／O操作及与使用控件建立与访问历史数据数据库,最后给出仿真实例界面。     

Analysis of control interval for foundation fieldbus-based control systems

Fieldbus-based control systems (FCS) have been increasingly used in process automation. Some processes and dynamic specifications need higher control frequencies to avoid instability. The aim of this paper is to analyze the temporal characteristics of communication and computation tasks and the configuration of the function blocks in a FCS and to allow the control interval to be shortened. An FCS for a water tank process is used as a case study. The experimental results show that the execution time of function blocks and the margin time are dominant over communication delays, and optimizing configuration by reducing the number of external links can contribute to increasing the control frequency.     

基于软件芯片的可重构远程故障诊断系统*

提出了一种具有充分柔性与可重构性的远程故障诊断系统的结构模型,利用软件芯片技术对系统中的各功能模块进行封装,并描述了系统的运行原理。根据应用设备的不同要求,通过系统数据组织、诊断芯片适配和运行结构设计,可以快速重构出不同的诊断系统。     

To lock, or not to lock: That is the question

Mechanisms to control concurrent access over project artefacts are needed to execute the software development process in an organized way. These mechanisms are implemented by concurrency control policies in version control systems that may inhibit (i.e. ‘to lock’) or allow (i.e., ‘not to lock’) parallel development. This work presents a novel approach named Orion that analyzes the project's historical changes and suggests the most appropriate concurrency control policy for each software element. This suggestion aims at minimizing conflict situations and thus improving the productivity of the development team. In addition, it identifies critical elements that do not work well with any of these policies and are candidates to refactoring. We evaluated Orion through two experimental studies and the results, which indicated it was effective, led us to a prototype implementation. Apart from the Orion approach this paper also presents the planning, execution, and analysis stages of the evaluation, and details of prototype internals.     

基于多线程的文件推送系统的设计与实现

气象部门采用传统的FTP数据文件推送方式存在着几个不足：问题之一就是难以实现实时快速将数据中心的有关数据文件传送到所需要的相关下级业务部门;问题之二是难以根据数据文件自身具有的重要性实时进行传送;问题之三是难以满足用户需要的采用定制来实时推送相应的数据文件。基于多线程的应用,以Socket为推送技术,实现对多类数据源进行实时决速的多目的传送,结合数据库技术实现了使用者对数据文件的查询、统计和实时管理等操作。测试结果表明：在满足用户的功能需求的同时,系统能有效解决以上存在的不足,并且实现了对数据的后期管理,对日志的查询筛选等数据管理功能。     

基于混合加密的可信软件栈数据封装方案

可信计算的RSA密钥机制会制约运算速度。为此,提出一种基于混合加密的可信软件栈数据封装方案。介绍可信软件栈的结构以及密封过程和解封过程,改进可信密码模块功能函数。实验结果表明,该方案能减少加密时间,适用于较大数据量的密封,能在较小性能损失的情况下,保障用户数据安全。     

基于DCS的循环流化床锅炉FSSS系统的实现

简要的介绍了循环流化床锅炉以及其保护系统FSSS的基本知识。以越南林同铝厂热电站的DCS控制系统项目为背景较为详细地介绍了如何在Honeywell的DCS系统中实现FSSS系统的功能,并且对FSSS系统的具体逻辑实现进行了详细的讲解。     

锅炉的计算机冗余控制系统

锅炉计算机自动控制系统,可为操作人员提供方便的数据显示和操作,系统的多级报警功能,可提示系统故障和维修措施。自动控制系统设备可冗余互补工作,提高了锅炉系统的稳定性和安全性。