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关键词： 状态事件故障树   交互马尔可夫链   平均时间分析   形式化方法  

摘要： 状态事件故障树是一种适合于描述构件化嵌入式系统失效因果链的建模技术,其顶层事件描述失效发生的结果.对顶层事件发生的平均时间进行分析,是获得系统平均失效时间参数的一种有效方法,可为系统的安全性评估提供支持.由于状态事件故障树缺乏严格语义,使得必须先对其进行形式化描述才能进行定量分析.为此,提出了一种基于交互马尔可夫链的状态事件故障树时间特性分析方法.首先,精化交互马尔可夫链的交互动作,建立接口交互马尔可夫链模型,并基于该模型对状态事件故障树的构件和逻辑门进行形式语义描述;其次,通过并行组合构件与逻辑门的形式语义模型,得到整个状态事件故障树的形式语义模型,并在该过程中使用弱互模拟对状态空间进行约简;然后,基于状态事件故障树的形式语义给出顶层事件发生的平均时间计算方法;最后,给出飞机着陆雷达控制系统和喷淋防火系统的状态事件故障树时间特性分析的实例研究.为构件化系统失效时间特性的分析提供了一种新方法.

关键词： 雷达   伺服性能   在线自动测试   面向对象  

摘要： 雷达伺服性能的在线自动测试对系统调试和维护具有十分重要的意义。文中在认真梳理雷达伺服性能测试方法的基础上,采用面向对象设计方法实现了在线自动测试。经多套伺服系统的在线实际验证,该测试模块使用方便,可信度高,具有很高的工程应用价值。

关键词： 软件可信   运行监控   体系设计  

摘要： 随着网络信息技术的不断进步,计算机网络技术在人们工作和生活中的应用越来越普遍,计算机网络软件已经成为人们日常工作应用的一部分。然而值得注意是,计算机网络软件的使用必须拥有一定的可信度,否则就会对用户计算机网络的正常使用造成一定信息泄露的危险。如何对软件体系的实时运行进行监控和控制,保证软件的可信程度,是软件设计必须要考虑的问题。笔者将对支持运行监控的可信软件体系结构的设计做出具体的分析和讨论。

关键词： DOD   AF   体系结构设计   作战视图   系统视图  

摘要： 针对装备体系结构设计标准不统一,装备之间互操作性差的问题,借鉴了美军的国防部体系结构框架,分析了其作战视图和系统视图在装备需求阶段需要重点回答的问题,研究了由作战视图产品向系统视图产品的映射方法,分析归纳了以数据为核心的体系结构产品开发顺序。

关键词： 结构化   设计   道路桥梁   应用  

摘要： 随着我国经济的不断发展以及人们生活水平的不断提高，很好地促进了桥梁工程的发展。在桥梁工程发展的同时，其结构设计方面是桥梁工程的重要内容。在对其结构进行设计的过程中，必须要从桥梁工程现场的实际情况进行出发，使其设计的内容不管是在理论方面能够满足施工条件，同时在实际施工过程中也能够使其满足。本文主要对结构化的设计在道路桥梁设计中的应用进行了分析，进而提出了一些要求。

关键词： 结构化设计   道路桥梁设计   具体应用  

摘要： 经济建设的不断变化发展,从而使得交通建设也发生了根本性的转变,道路桥梁设计作为交通运输中重要的组成部分之一,对其有着极其重要的影响和作用。文章主要结合道路桥梁设计中如何进行结构化设计进行了简要的分析与总结,并针对存在的问题提出了合理化的解决方法,以便更好的促进我国交通运输业的发展,仅供同仁参考。

关键词： formal method   Cloud computing   resources scheduling  

摘要： In the virtualization based cloud computing environment, multiple computers are allowed to run as virtual machines (VM) in a single physical computer. Efficient scheduling of limited underlying resources has been a key issue. This paper presents a formal method of CPU resources scheduling (FRS). VMs are divided into three resources statuses according to resources requirements and their run information. FRS scheduling is formally scheduling CPU resources according to the resources statuses. The implementation of FRS is confined to the VMM layer, without VM dependency. The evaluation shows that idle CPU resources of VMs are be used by those VMs which need more CPU resources and the CPU resources overall utilization is improved.

关键词： SOFTWARE engineering   COMPUTER-aided software engineering   SPECIFICATIONS   SOFTWARE productivity   ALGORITHMS  

摘要： Software engineering is concerned with the design, development and maintenance of large software using systematic techniques. Research performed in software engineering includes a variety of topics like studies on psychological aspects of teams developing software, new agile methodologies, software processes and architectures, model-based development approaches, and validation and verification, to mention only a few. Though the discipline has considerably advanced in the last twenty years, it still lacks a formal and rigorous approach in some of its specific topics or subareas, making it difficult to assess in general that a software product satisfies its requirements. Besides, some specific software development standards require a certain minimum level of rigorousness in the development and validation of tools in order to be certified, justifying the use of more formal techniques.

关键词： Digital factory   Manufacturing system design   Petri nets   Semantic models   Virtual reality  

摘要： The work presented in this paper outlines a design framework for flexibly automated manufacturing cells in a Virtual Reality environment. Design encompassing structure/configuration and control/operation aspects of manufacturing cells is supported through different levels of analysis. The cornerstone is semantic models that are constructed for stereotypical manufacturing cell objects and their relations but are extensible for new ones. VRML 3D models of these objects are created and introduced into the virtual world. Core methods are developed for object functional control. A major class of methods at object level refers to trivial and non-trivial kinematics for stereotypical objects such as robots, machine tools and conveyors. The main method at cell level pertains to controlling interactions among different manufacturing tasks and is based on definition of control-interpreted Petri Nets at two levels of detail: generic nets, which are less detailed and directly derive from semantic models, and specific nets, which add further detail that cannot be included in a practical way in the semantic nets. Furthermore, special attention is directed to the user within the virtual environment, by providing mostly visual tools that enhance user perception as well as information and manipulation tools that facilitate interaction with the virtual manufacturing cell being designed. The virtual environment was developed from scratch using relatively high-level 3D graphics development tools and open libraries and is thus amenable to extensions.

关键词： COMMUNICATIVE competence   SCHOLARSHIPS   PATIENTS -- Psychology   PAIN management   SYMPTOMS