混合系统的分析

在人们日常生活中,混合系统(Hybrid Sstem)应用的实例很多,如汽车中的计算机控制系统、飞机中的平稳飞行痤制系统等都属于混合系统的范畴,并且随着计算机技术的发展,混合系统的应用范围会更加广泛,入们的生活会更加依赖于混合系统,固此社会应用的需求要求研究人员对混合系统进行比较深入的研究,保证混合系统运行的正确性。     

混合系统的形式验证技术及其在化工过程控制中的应用

针对PLC等逻辑控制器控制连续对象的可靠性问题。给出了混合系统的形式验证的方法,即用混合矩形自动机建模,通过其商迁移的可达性分析,证明了控制程序的正确性,应用实例表明该方法是可行和有效的。     

基于多面体包含的非线性混成系统可达性分析

针对一类非线性混成系统的可达性问题,提出了一种基于多面体包含的分析方法。首先介绍了混成系统及其可达性,讨论了如何应用多面体包含对多项式混成系统进行线性近似,并采用量词消去和非线性优化方法来构造相应的线性混成系统,然后运用验证工具SpaceEx求得原非线性混成系统的过近似可达集,并应用于验证系统的安全性。     

混合投影时序逻辑与混合系统的形式化验证

为了描述混合系统的性质和行为，10多年来，各种时序逻辑，如Hybrid Temporal Logic等相继出现。这些时序逻辑适用于刻画混合系统的性质和规范，但不适宜表示描述系统的实现模型。本文定义了一个混合投影时序逻辑（Hybrid Projection Temporal Logic，简称HPTL），既能刻画混合系统的性质，又能表示混合系统的实现。这样，混合系统的验证就可以很方便地在统一的数学模型框架下进行。同时，给出了HPTL的基本的逻辑等价式系统和一个用HPTL进行混合系统验证的实例。     

标记迁移系统的组合可达性分析

标记迁移系统是一种在计算机辅助设计和验证中得到广泛使用的形式模型。当系统中的模块比较多时,系统的整体模型有可能出现状态空间的指数级爆炸,组合可达性分析是缓解这一问题的一种有效方法。已有的工作缺乏对该方法基本原理的清晰描述和精确表达。本文对其基本原理进行了分析和概括,并作了形式化陈述,证明了相关结论。本文的工作有助于深入理解和澄清组合可达性分析的内部工作机制。     

混合系统的稳定性分析

研究了混合系统的稳定性问题.首先,对于混合系统给出了一种一般的模型,该模型能够描述混合状态的跳变现象.然后,定义了一种辅助函数作为系统能量的一种度量.基于该模型和辅助函数,得到了混合系统稳定性判定的一些新结果.这些结果给出了在离散状态改变时,在由于连续状态的跳变而引起的系统能量增加的情况下,混合系统仍保持稳定的充分条件.最后,给出了一种能量函数的寻找方案,并利用一个仿真实例验证了该方案的有效性.     

时间自动机可达性分析算法的改进

模型检测时,实时系统的大多数安全属性和部分活性都可以通过可达性分析算法来验证。本文介绍了时间自动机和可达性分析算法,并对可达性分析算法中的后继算法进行了改进。     

混合系统建模理论与混合系统模型

在现代工程仿真中,大部分仿真对象表现出同时具有连续和离散对象的特征,利用现有的离散或者连续建模理论不能全面的反应出对象特性,需要对混合系统的建模进行相应的理论研究.从系统理论出发,围绕着系统的连续属性和离散属性,以及他们对系统信息的响应,还有他们之间的相互作用为中心,建立混合系统模型的形式化表达和系统理论基础,并在此基础上建立了混合系统模型.以此模型为基础,在实践中为某大型仿真项目中的工程对象建立了混合模型,在仿真中得到有效的应用.     

BACH:线性混成系统有界可达性模型检验工具

混成自动机的模型检验问题非常困难,即使是其中相对简单的一个子类--线性混成自动机,它的可达性问题仍然是不可判定的.现有的相关工具大都使用多面体计算来判定线性混成自动机状态空间的可达集,复杂度高、效率低,无法解决实际应用规模的问题.描述了一个面向线性混成系统有界可达性模型检验工具--BACH(bounded reacha...     

Towards an Efficient Path-Oriented Tool for Bounded Reachability Analysis of Linear Hybrid Systems using Linear Programming

The existing techniques for reachability analysis of linear hybrid automata do not scale well to problem sizes of practical interest. Instead of developing a tool to perform reachability check on all the paths of a linear hybrid automaton, a complementary approach is to develop an efficient path-oriented tool to check one path at a time where the length of the path being checked can be made very large and the size of the automaton can be made large enough to handle problems of practical interest. This approach of symbolic execution of paths can be used by design engineers to check important paths and thereby, increase the faith in the correctness of the system. Unlike simple testing, each path in our framework represents a dense set of possible trajectories of the system being analyzed. In this paper, we develop the linear programming based techniques towards an efficient path-oriented tool for the bounded reachability analysis of linear hybrid systems.     

An Automata-Theoretic Approach to the Reachability Analysis of RPPS Systems

We show how the tree-automata techniques proposed by Lugiez and Schnoebelen apply to the reachability analysis of RPPS systems. Using these techniques requires that we express the states of RPPS systems in a tailor-made process rewrite system where reachability is a relation recognizable by finite tree-automata.     

时间符号迁移图上的可达性分析

提出了以时间符号迁科为建模语言、基于可达性分析的模型检测算法，并给出了算法的正确性证明。该算法可被用于硬件设计和通信协议验证等领域。     

Reachability Analysis over Term Rewriting Systems

This paper surveys some techniques and tools for achieving reachability analysis over term rewriting systems. The core of those techniques is a generic tree automata completion algorithm used to compute in an exact or approximated way the set of descendants (or reachable terms). This algorithm has been implemented in the tool. Furthermore, we show that many classes with regular sets of descendants of the literature corresponds to specific instances of the tree automata completion algorithm and can thus be efficiently computed by . An extension of the completion algorithm to conditional term rewriting systems and some applications are also presented.     

Language-Emptiness Checking of Alternating Tree Automata Using Symbolic Reachability Analysis

Alternating tree automata and AND/OR graphs provide elegant formalisms that enable branching- time logics to be verified in linear time. The seminal work of Kupferman et al. [Orna Kupferman, Moshe Y. Vardi, and Pierre Wolper. An automata-theoretic approach to branching-time model checking. J. ACM, 47(2):312–360, 2000] showed that 1) branching-time model checking is reducible to the language non-emptiness checking of the product of two alternating automata representing the model and property under verification, and 2) the non-emptiness problem can be solved by performing a search on an AND/OR graph representing this product. Their algorithm, however, can only be implemented in an explicit-state model checker because it needs stacks to detect accept and reject runs. In this paper, we propose a BDD-based approach to check the language non-emptiness of the product automaton. We use a technique called “state recording” from Schuppan and Biere [Viktor Schuppan and Armin Biere. Efficient reduction of finite state model checking to reachability analysis. Int. Journal on Software Tools for Technology Transfer (STTT), 5(2–3):185–204, 2004] to emulate the stack mechanism from explicit-state model checking. This technique allows us to transform the product automaton into a well-defined AND/OR graph. We develop a BDD-based reachability algorithm to efficiently determine whether a solution graph for the AND/OR graph exists and thereby solve the model-checking problem. While “state recording” increases the size of the state space, the advantage of our approach lies in the memory saving BDDs can offer and the potential it opens up for optimisation of the reachability analysis. We remark that this technique always detects the shortest counter-example.     

基于状态可达图的离散事件系统时态性质分析

离散事件系统的许多重要性质可用时态逻辑方便，直接和简明地进行描述，系统的性质分析可转化成时态满足关系的判定。基于状态可达图，给出了有限系统时态特征的判定方法。