基于UPPAAL的AADL模型可调度性验证

针对体系结构分析设计语言(AADL)模型的可调度性验证问题,提出了利用模型检测工具UPPAAL对其线程组件在非抢占型调度策略下的可调度性进行形式化分析和验证的方法,并实现了从AADL模型到UPPAAL中模型的模型转换工具。实验结果证明了通过UPPAAL来分析和验证AADL模型的可调度性问题的可行性。相比其他方法而言,基于形式化理论的本方法的验证结果更加精确。     

基于体系结构模型的综合化航电分区可调度性验证

分区可调度性验证是影响综合模块化航电系统(IMA)可靠性与安全性的关键问题。为解决现有的模型驱动验证方法难以满足系统整体验证需求或需要繁琐的二次建模的问题,提出一种基于体系结构分析与设计语言(AADL)的IMA分区可调度性验证建模方法。在构建分区静态体系结构模型的基础上,通过AADL行为附件建模描述系统中任务的调度过程。再采用AADL Inspector工具对模型中的任务调度行为进行动态仿真,根据仿真结果即可对IMA分区可调度性进行评估。案例实验表明,该方法能够有效发现分区调度配置信息中的错误。此外,只需一次性建模即可直接完成可调度性验证。与现有方法相比,避免了对AADL模型进行繁琐的二次转化。     

多处理器实时系统可调度性分析的UPPAAL模型

随着多处理器实时系统在安全性攸关系统中的广泛应用,保证这类系统的正确性成为一项重要的工作.可调度性是实时系统正确性的一项关键性质.它表示系统必须满足的一些时间要求.传统的可调度性分析方法结论保守或者不完备,为了避免这些方法的缺陷,提出使用模型检测的方法来实现可调度性分析.提出了一个用于多处理器实时系统可调度性分析的模板,将与系统可调度性相关的部分包括实时任务、运行平台和调度管理模块都用时间自动机建模,并使用UPPAAL验证可调度的性质是否总被满足.符号化模型检测方法被用于推断可调度性,但是由于秒表触发的近似机制,符号化模型检测方法不能用于证明系统不可调度.作为补充,统计模型检测方法被用于估算系统不可调度的概率,并在系统不可调度时生成反例.此外,在系统可调度时,通过统计模型检测方法获取一些性能相关的信息.     

基于Uppaal的实时系统AADL数据流模型的转换与验证

体系结构分析设计语言AADL是一种可支持软硬件一体化建模及同一模型多元分析的形式化与图形化建模语言。采用时间自动机形式化模型检验方法对AADL模型中的数据流进行转换和验证。考虑到单一数据流与混合数据流的差异性,分别设计了数据流到时间自动机模型的转换规则,并通过时间自动机网络实现数据流的综合分析。设计开发了自动化模型转换的插件AADLToUppaal Plug-in,将其嵌入到OSTATE工具中,使用时间自动机建模与验证工具Uppaal对转换得到的时间自动机进行模拟和验证,等价地验证所设计的AADL模型数据流时延是否满足系统实时性要求。仿真实验结果表明,所设计的数据流模型转换方法能有效地将AADL模型转换到时间自动机模型,并能在Uppaal中正确地分析原模型的数据流时延特性。     

基于AADL的综合航电分区系统可调度性判定

综合模块化航电(IMA)系统中的分区系统提高了其可靠性和安全性,但在系统设计和实现过程中,应采用各种分析和验证方法确保系统的时间需求得到满足。为此,针对符合ARINC653规范的IMA系统,根据分区系统层级调度的特性,提出一种基于仿真的分区任务集可调度性判定方法。借助Cheddar工具及其自定义调度策略功能,使架构分析和设计语言(AADL)具有对分区系统进行建模的能力,并利用该工具对AADL模型进行仿真以判定系统的可调度性。实例分析结果表明,该方法能自动、准确、快速地进行可调度性判定,并以甘特图的方式绘制任务调度过程,得到直观、详细的结果。     

基于时间自动机的嵌入式系统调度分析工具

为验证嵌入式实时系统开发过程中任务集的可调度性,设计并实现一种嵌入式系统调度分析工具。提出通用任务模型,建立任务与事件到达自动机和任务状态自动机的状态关系映射,利用基于模型检测的时间自动机可达性方法判定系统的可调度性。仿真实例结果表明,该工具的分析准确性较高。     

AADL模型的形式化研究

在嵌入式系统建模领域,AADL以其软硬件协同建模的特点已经逐渐成为业界的标准。围绕AADL的形式化特点,国内外众多学者展开了热烈的讨论。为了帮助系统开发人员深入了解AADL,指导软件开发进程,提高基于AADL模型的软件开发效率,分别从AADL模型可靠性分析、可调度性分析以及AADL模型测试这三个不同角度综述了已经出现的各种AADL形式化验证理论,对比分析了它们的优点和不足。简要介绍有关AADL验证工具,研究基于AADL模型的嵌入式开发平台的构建。     

AADL模型的形式化研究

在嵌入式系统建模领域,AADL以其软硬件协同建模的特点已经逐渐成为业界的标准。围绕AADL的形式化特点,国内外众多学者展开了热烈的讨论。为了帮助系统开发人员深入了解AADL,指导软件开发进程,提高基于AADL模型的软件开发效率,分别从AADL模型可靠性分析、可调度性分析以及AADL模型测试这三个不同角度综述了已经出现的各种AADL形式化验证理论,对比分析了它们的优点和不足。简要介绍有关AADL验证工具,研究基于AADL模型的嵌入式开发平台的构建。     

基于时间自动机的AADL端到端流规约验证方法

体系结构分析及设计语言(AADL)作为一种标准且直观的实时系统分析与设计工具，可以为系统设计、分析、验证、自动代码生成等关键环节提供统一的抽象表示。然而，AADL模型采用仿真的验证方法无法得到精确的端到端延迟验证结果，尤其是对于资源动态分配的实时系统。为解决结果不精确的问题，可结合基于系统有穷状态空间遍历的模型检验方法。首先，将实时系统AADL模型转换为时间自动机(TA)模型，以TA为理论体系进行模型检验。其次，基于反应链的需求分类定义端到端延迟需求表达模式。最后，给出对应需求模式的观察者模型，与系统模型并行组合，优化模型验证的时空资源消耗。     

ARINC653航空电子系统AADL建模技术研究

随着ARINC653系统在我国航空领域的广泛应用,研究ARINC653系统建模方法将为进一步研究基于模型的ARINC653系统可靠性、可调度性分析奠定基础.详细研究了ARINC653系统AADL建模的方法,具体描述了ARINC653系统、分区、进程、进程通信和健康监控等核心元素的AADL建模映射机制,并进行实例说明.     

Fast and precise points-to analysis

Many software engineering applications require points-to analysis. These client applications range from optimizing compilers to integrated program development environments (IDEs) and from testing environments to reverse-engineering tools. Moreover, software engineering applications used in an edit-compile cycle need points-to analysis to be fast and precise.In this article, we present a new context- and flow-sensitive approach to points-to analysis where calling contexts are distinguished by the points-to sets analyzed for their call target expressions. Compared to other well-known context-sensitive techniques it is faster in practice, on average, twice as fast as the call string approach and by an order of magnitude faster than the object-sensitive technique. In fact, it shows to be only marginally slower than a context-insensitive baseline analysis. At the same time, it provides higher precision than the call string technique and is similar in precision to the object-sensitive technique. We confirm these statements with experiments using a number of abstract precision metrics and a concrete client application: escape analysis.     

源代码分析技术的理论与实践发展

源代码分析技术对于软件安全缺陷分析是一项非常重要的手段.分析了软件源代码分析工具的技术手段和发展过程,最后对源代码分析的理论和实践进行了分析总结.     

C语言的别名分析方法研究

别名分析对于数据流分析、程序优化和分析工具的实现非常重要.文章提出了一种需求驱动,流非敏感的分析算法来解决指针别名问题.通过构造程序表达式图(PEG)把指针别名问题转化成判断两个指针节点是否是联通的问题,它不同于传统的别名分析方法,它不需要构造别名集合和对其求交集,所以提高了分析指针别名的效率.     

The use of protocol analysis for determining ability requirements for personnel selection on a computer-based task

Abstract

The role of cognitively oriented tasks in the workplace continues to increase as automation of physical task components advances. Difficulties in automating the operator's cognitive processes have placed a renewed emphasis on the human component in advanced manufacturing systems. While traditional task analysis techniques have made significant contributions to improving productivity when important task elements are visually observable, their focus on manual task procedures make them less effective for cognitively oriented activities. This research has made a first attempt at integrating techniques from several disciplines to develop a cognitive task analysis methodology. The utility of this combined approach is examined for a new system being tested in the United States Postal Service. This task requires operators to encode, via a keyboard, addresses presented on a video display terminal. Results support the hypothesis that, for cognitively oriented tasks, a consensus based analysis technique (the Position Analysis Questionnaire) can be significantly improved by including data from task analysis provided the methodology is suitable for identifying non-physical task components.     

A system to assist survey analysts

The researcher who knows little about computers but wants to conduct a survey and analyse the results by computer can land himself in some difficulty if he does not appreciate some of the problems of computerization. This paper describes a system which is designed to aid such a person by providing assistance with the design of the questionnaire, the capturing of the data and the final analyses.     

A novel analysis space for pointer analysis and its application for bug finding

The size of today’s programs continues to grow, as does the number of bugs they contain. Testing alone is rarely able to flush out all bugs, and many lurk in difficult-to-test corner cases. An important alternative is static analysis, in which correctness properties of a program are checked without running it. While it cannot catch all errors, static analysis can catch many subtle problems that testing would miss.We propose a new space of abstractions for pointer analysis—an important component of static analysis for C and similar languages. We identify two main components of any abstraction—how to model statement order and how to model conditionals, then present a new model of programs that enables us to explore different abstractions in this space. Our assign-fetch graph represents reads and writes to memory instead of traditional points-to relations and leads to concise function summaries that can be used in any context. Its flexibility supports many new analysis techniques with different trade-offs between precision and speed.We present the details of our abstraction space, explain where existing algorithms fit, describe a variety of new analysis algorithms based on our assign-fetch graphs, and finally present experimental results that show our flow-aware abstraction for statement ordering both runs faster and produces more precise results than traditional flow-insensitive analysis.     

基于因子分析法和聚类分析法的副省级城市宜居情况聚类评价

重点选取了15个副省级城市的第一产业比重、人口密度、人均绿地、园林面积、医院数目,市政建设面积、地方财政税收等42个指标,使用SPSS作为计算工具,使用因子分析方法简化评价指标,计算相关系数矩阵,判别因子分析可行性,利用主成分分析法求因子载荷,将因子进行旋转得出更有实际意义的因子解释,并计算因子得分,利用该结果计算Mi...     

Cost analysis of object-oriented bytecode programs

Cost analysis statically approximates the cost of programs in terms of their input data size. This paper presents, to the best of our knowledge, the first approach to the automatic cost analysis of object-oriented bytecode programs. In languages such as Java and C#, analyzing bytecode has a much wider application area than analyzing source code since the latter is often not available. Cost analysis in this context has to consider, among others, dynamic dispatch, jumps, the operand stack, and the heap. Our method takes a bytecode program and a cost model specifying the resource of interest, and generates cost relations which approximate the execution cost of the program with respect to such resource. We report on COSTA, an implementation for Java bytecode which can obtain upper bounds on cost for a large class of programs and complexity classes. Our basic techniques can be directly applied to infer cost relations for other object-oriented imperative languages, not necessarily in bytecode form.     

数据分析需求与实现

数据分析是从海量数据中发现隐含信息或知识的过程。基于一个公安破案辅助数据分析系统,深入研究数据分析任务的需求与实现,提出首先规划分析思路、细化分析功能,然后用多视角数据透视和智能分析两种手段,从微观与宏观、定量与定性等不同角度互为补充地使系统具有完备的分析功能。该研究对如何开发具有实用价值的数据分析系统有普遍的指导意义。