使用时间化自动机形式化带有时间扩展的UML状态图

严格建模是嵌入式实时系统设计的核心技术，通过UMI。方法与形式化方法结合可以给严格建模提供很好的工具支持。时间化自动机(Timed Automata)是一种用于描述、验证实时系统的理论模型。文中提出了一种通过时间化自动机来形式化带有时间扩展的UML状态图的方法，这种方法为UMI。与形式化方法的结合构造了桥梁作用。带有时间扩展的UML状态图用于嵌入式系统动态模型的建模，从时间化自动机模型得到形式化规范将更容易。UML状态图的形式化分为两部分完成；层次状态图的平面化以及时间化自动机的构造。  

并发和实时系统的模型检验技术

模型检验是一种重要的自动验证技术，通过显式状态搜索或隐式不动点计算来验证并发或实时系统的模态／命题性质，以保证通信协议、数字电路等设计的正确性。详细阐述了模型检验技术的发展与研究现状。首先描述了并发系统分别基于自动机理论和符号化的两种主要模型检验策略，并给出解决状态爆炸问题的主要方法；然后介绍了针对实时系统以及面向对象设计的模型检验方法；对每种方法都介绍了相应的典型工具，最后分析了模型检验面临的困难以及今后的发展趋势。  

有限精度时间自动机的可达性检测

为了缓解状态空间爆炸问题,减小模型检测过程中生成的状态空间,加快模型检测速度,引入有限精度时间自动机(finite precision timed automata,简称FPTA)作为实时系统的形式模型,并提出了一种数据结构SDS(series of delay sequence)符号化表示状态空间中的状态集.FPTA只记录时钟变量的整数值及时钟变化的先后次序,从而减小生成的状态空间.在一定的时间约束下,Alur与Dill提出的时间自动机的可达性检测可简化为FPTA的可达性检测.举例描述了状态空间的生成过程和表示方法.最后,列出部分初步的实验结果,分析了SDS的特点及不足.  

基于UPPAAL的实时系统模型验证

UPPAAL是一种使用时间自动机模型的实时系统验证工具，它可以避免时间自动机求积时状态空间的爆炸。介绍了时间自动机理论和工具UPPAAL，着重说明如何用UPPAAL进行模型检查，并给出了一个应用实例。  

Forward Analysis of Updatable Timed Automata

Timed automata are a widely studied model. Its decidability has been proved using the so-called region automaton construction. This construction provides a correct abstraction for the behaviours of timed automata, but it suffers from a state explosion and is thus not used in practice. Instead, algorithms based on the notion of zones are implemented using adapted data structures like DBMs. When we focus on forward analysis algorithms, the exact computation of all the successors of the initial configurations does not always terminate. Thus, some abstractions are often used to ensure termination, among which, a widening operator on zones.In this paper, we study in detail this widening operator and the corresponding forward analysis algorithm. This algorithm is most used and implemented in tools like KRONOS and UPPAAL. One of our main results is that it is hopeless to find a forward analysis algorithm for general timed automata, that uses such a widening operator, and which is correct. This goes really against what one could think. We then study in detail this algorithm in the more general framework of updatable timed automata, a model which has been introduced as a natural syntactic extension of classical timed automata. We describe subclasses of this model for which a correct widening operator can be found.  

UPPAAL--一种适合自动验证实时系统的工具

UPPAAL是一个基于时间自动机的自动验证工具,已成功地用于实时控制器和通信协议等实时系统的验证.本文介绍了UPPAAL的语法,语义和语用,列举了它的几种扩展形式,并归纳了其应用及研究现状.  

AFDX冗余管理机制的仿真

介绍了AFDX系统的组成及体系结构,通过对AFDX实时通信协议的冗余管理机制和冗余帧处理算法的分析和研究,提出具有较高可靠性的冗余帧处理算法ESKM.并通过时间自动机理论和UPPAAL工具模拟仿真,验证了其满足航空电子网络数据传输的可靠性需求.  

Model-checking discrete duration calculus

Duration Calculus was introduced in [ZHR91] as a logic to specify and reason about requirements for real-time systems. It is an extension of Interval Temporal Logic [Mos85] where one can reason about integrated constraints over time-dependent and Boolean valued states without explicit mention of absolute time. Several major case studies, e.g. the gas burner system in [RRH93], have shown that Duration Calculus provides a high level of abstraction for both expressing and reasoning about specifications. Using Timed Automata [A1D92] one can express how real-time systems can be constructed at a level of detail which is close to an actual implementation. We consider in the paper the correctness of Timed Automata with respect to Duration Calculus formulae. For a subset of Duration Calculus, we show that one can automatically verify whether a Timed Automaton is correct with respect to a formulaD, abbreviated D, i.e. one can domodel-checking. The subset we consider is expressive enough to formalize the requirements to the gas burner system given in [RRH93]; but only for a discrete time domain. Model-checking is done by reducing the correctness problem D to the inclusion problem of regular languages.