基于层次实时有色Petri网的实时系统建模与分析方法研究

Petri网是一种基于图形进行模拟和分析的数学工具,能够描述系统的异步和并发行为,但是现有高级Petri网不能对嵌入式实时系统进行完整的模拟与实时性分析。该文首先通过扩展有色Petri网提出了层次实时有色Petri网模型,然后描述了嵌入式实时系统的建模和实时性分析方法。最后,将该文提出的方法应用于硬实时系统列车通信网络MVB总线控制器的建模和实时性分析过程,仿真和分析结果表明,该方法能够满足列车通信网络系统设计对MVB总线控制器的功能验证和实时性分析需求。     

需求演化过程建模

对需求任务、需求活动、需求工程过程以及需求工程过程系统进行形式化定义.用信息熵对需求任务演化进行度量,用联合熵对需求活动、需求工程过程以及需求工程过程系统演化进行度量.从需求工程过程的角度,用条件-事件网对需求工程过程的迭代、反馈进行微观演化建模.从系统工程的角度,用耗散结构理论对整个软件需求工程过程系统进行宏观演化建模.     

含有非马尔可夫过程的排队Petri网模型和性能分析

本文提出了一种新的高级性能模型技术,称作NM-QPN(含有非马尔可夫过程的排队Petri网,Queuing Petri Net including Non-Markovian processes),它综合了排队网,随机Petri网以及模拟求解各自的特点.NM-QPN以模拟模型为总体框架,发挥排队网和随机Petri网各自的优势对系统进行建模.提出了一套完整的NM-QPN模型求解方案,通过流等价方法将模型中的马尔可夫过程进行化简,这样可以大大减少模型的状态,最后再用模拟求解方法求解剩下的非马尔可夫过程.     

敏捷需求过程建模

将敏捷方法融入软件需求工程过程的每一个活动之中,充分发挥敏捷方法和计划驱动方法的优势,体现了规范的力量和安慰以及敏捷的宽松和创造性,并用双变迁Petri网DTPN为敏捷需求工程过程活动建立反馈、迭代模型.     

SPN在网络安全保密系统可靠性分析中的应用

文章针对网络安全保密系统的安全需求和运行特性,引入Petri网理论指导网络安全保密系统的可靠性建模与分析过程。首先详细描述了运用随机Petri网对网络安全保密系统进行可靠性建模与分析的具体方法和过程;然后给出一个实例,对系统的保密性服务子系统进行建模,并分析了该子系统在安全运行状态下的可靠性。通过对可靠性建模分析方法的应用,不仅实现了系统方案设计阶段可靠性的可评估性,而且提高了系统后期开发过程的可操作性。     

铁路计算机联锁软件测试技术的优化实现

铁路信号的联锁逻辑非常复杂,针对联锁逻辑的测试工作也就十分的艰巨.目前计算机联锁软件测试领域所涉及的测试技术也在不断研究过程中,将Petri网等形式化描述方法引入联锁测试是国内外研究的一个重要方向.介绍了软件测试的一般方法,并引入有色Petri网的概念与特点,将有色Petri网建模方法应用到计算机联锁软件测试技术中,给出一种优化实现.     

有色Petri网在C~3I系统建模中的应用

C3I系统对现代化战争的支持越来越大，许多发达国家均投入大量人力和物力来提高C3I系统的性能，但是系统多维性和复杂性使得系统的建模一直是一个难点，至今还没有较好的系统化的模型产生。本文讨论了一种基于有色Petri网的模型的建立方法，克服了以往用普通Petri网建模的一些缺点。     

利用CPN分析通信装备战场抢修系统效能

基于有色Petri网理论,运用建模与仿真技术,对通信装备战场抢修系统效能进行了分析;运用CPN-tools对具体实例进行了仿真实现,其运行结果与该抢修系统的统计结果基本一致;证明了有色Petri网理论和仿真工具在本领域运用的可行性和科学性,为战场抢修系统的效能评估探索出了一种新的方法.     

基于有色Petri网模型的安全协议检测方法

提出了一种用有色Petri网对安全协议建模，并通过模拟和对状态空间检测来发现协议漏洞的方法。利用这一方法对著名的Needham-Schroedor公钥协议建模，然后用CPN Tools实现并对协议进行检测，发现了协议存在的漏洞。应用结果表明，方法有效。     

基于Petri网的入侵检测模型研究

随着计算机网络的广泛应用,非法的入侵与攻击行为不断发生,严重威胁着网络信息的安全,对入侵和攻击进行检测与防范已经成为刻不容缓的重要课题。讲述了Petri网(PN)和有色Petri网(CPN),通过将入侵分为“存在”,“顺序”,“偏序”三种类型,描述入侵检测系统(IDS)中的攻击模式用Petri网实现,并且给出了使用有色Petri网描述攻击模式。     

Risk assessment of software-system specifications

This paper presents a methodology and an example of risk assessment of functional-requirement specifications for complex real-time software systems. A heuristic risk-assessment technique based on CPN (colored Petri-net) models is presented. This technique is used to classify software functional-requirement specification components according to their relative importance in terms of such factors as severity and complexity. A dynamic complexity measure, based on concurrence in the functional requirements, is introduced. This technique is applied on the Earth Operation Commanding Center (EOC COMMANDING), a large component of the NASA Earth Observing System (EOS) project. Two specification models of the system are considered. Results of applying this technique to both CPN models are presented. The risk assessment methodology in this paper suggests the following conclusions: (i) risk assessment at the functional-requirement specification phase can be used to classify functional requirements in terms of their complexity and severity; (ii) dynamic complexity metrics and the concurrence metric can be important in assessing the risk factors based on the complexity of functional specifications; (iii) the concurrence complexity metric is an important aspect of dynamic complexity; and (iv) CPN models can be used to build an executable specification of the system, which helps the analyst not only to acquire deep understanding of the system but also to study the dynamic behavior of the system by simulating the model     

A Software Safety Requirements Elicitation Approach Based on Hazardous Control Action Tree Modelling

Software safety requirements are crucial for safety assurance of safety-critical software systems.A novel accident causality model,Systems-theoretic accident modeling and processes (STAMP),has been proposed to overcome the limitations of traditional safety techniques in software safety requirements elicitation.However,the STAMP-based method is ad-hoc with no rigorous procedure to elicit software safety requirements effectively.Furthermore,the time-related safety requirements,which are important to software safety,have been paid little attention in STAMP-based method.With the purpose of overcoming these limitations,this paper strives to find a systematic approach to elicit software safety requirements with STAMP,especially the time-related safety requirements.Firstly,a new process model of STAMP is proposed to model all the system varilables and the ralationship of them in control processes.Then based on the process model,an approach HCAT-SSRA is proposed to elicit the software safety requirements by building Hazardous control action tree (HCAT) for each control action in system control processes.Additionally,several rules are proposed to guide time-related software safety requirements analysis.Finally,a case study is given to illustrate the availability and feasibility of the proposed method.     

浅析中职教务管理系统需求

随着我国大力发展中等职业教育,各校招生规模不断扩大,采用传统的教务管理模式将会浪费大量的人力、物力、财力,所以教务管理系统的开发已成为中职学习工作的重点。为了满足学校教务工作的需求,教务管理系统共设置了五大子系统：用户权限管理子系统、教学计划管理子系统、成绩管理子系统、学生考勤管理子系统、教材管理子系统,并对系统功能和非功能需求进行分析。     

一种面向领域的软件组件模型的研究

面向领域的嵌入式系统具有严格实时性、资源受限性、特定领域需求、极高可靠性等特点,这些特点给嵌入式系统软件组件化技术的研究和应用带来了新的课题。文中提出了一种面向领域的软件组件模型,着重介绍了对软件组件的功能属性和非功能属性的考虑及实现。     

Combining aspects and object-orientation in model-driven engineering for distributed industrial mechatronics systems

Recent advances in technology enable the creation of complex industrial systems comprising mechanical, electrical, and logical – software – components. It is clear that new project techniques are demanded to support the design of such systems. At design phase, it is extremely important to raise abstraction level in earlier stages of product development in order to deal with such a complexity in an efficient way. This paper discusses Model Driven Engineering (MDE) applied to design industrial mechatronics systems. An aspect-oriented MDE approach is presented by means of a real-world case study, comprising requirements engineering up to code generation. An assessment of two well-known high-level paradigms, namely Aspect- and Object-Oriented paradigms, is deeply presented. Their concepts are applied at every design step of an embedded and real-time mechatronics system, specifically for controlling a product assembler industrial cell. The handling of functional and non-functional requirements (at modeling level) using aspects and objects is further emphasized. Both designs are compared using a set of software engineering metrics, which were adapted to be applied at modeling level. Particularly, the achieved results show the suitability of each paradigm for the system specification in terms of reusability quality of model elements. Focused on the generated code for each case study, statistics depicted an improvement in number of lines using aspects.     

基于CPN的服务交互行为关键属性的运行时确保机制

为了保证服务交互行为与其定义的关键属性相一致,本文提出了一种基于有色Petri网模型的运行时确保机制,从而提高服务组合运行的可靠性.文章首先介绍了服务交互行为CPN模型,用于精确刻画服务交互行为及其重要属性.结合服务实例,进一步对模型可达集和关键监控属性展开深入分析.在可达集的基础上,描述将模型运用于运行时监控的方式确...     

基于多粒度软件网络模型的软件系统演化分析

软件系统是一类典型的人工参与的复杂系统,理解软件系统的演化规律有助于更好地指导软件工程实践.本文从包、类和特征三个粒度上构建软件系统的网络模型,利用复杂网络理论依次从网络规模、质量、结构控制三方面定量分析软件系统演化规律.以经典的Lehman演化定律为基准,对比软件系统在不同粒度下的演化差异.研究结果表明：（1）不同粒度下软件系统表现出的演化特性有所不同,其中在类粒度下效果更好;（2）持续增长、持续变化、自我调节和主体维持四项定律表现出与构建软件网络的粒度无关;（3）包粒度下系统演化对软件质量影响不大,而反馈系统定律仅在类粒度下成立.     

Specifying software requirements

Many of the problems of software system development can be traced to poor understanding or specification of what the system is supposed to do. Much attention is now being given to producing requirements specifications that are understandable, formal, complete, and modifiable. The structure and content of conceptual models for problem understanding are discussed; such models can form the basis for requirements analysis. Techniques for "tuning" and formally specifying the conceptual model are surveyed, and the proper scope of a software requirements document-including nonfunctional requirements such as performance-is explained.