带数据约束的概率实时系统的验证

带数据约束的概率实时系统是指一种既带有概率时间约束又带有数据变量约束的计算系统。目前将离散数据约束和连续时间约束统一在一个概率模型中的规范及验证研究较少。提出了一种既带有连续数据约束又带有离散数据约束的规范——基于连续时间的概率ZIA规范,并给出了它的时序逻辑。对于CTL和PCTL而言,尽管这些逻辑很强大,但是只能反映时序性质,因此提出一个新的形式化语言CTML来表达度量性质查询,同时保留表达时序性质的能力并给出概率ZIA规范的验证算法。     

基于MARTE的面向混成系统的模型形式化转换

混成系统是离散逻辑跳转与实时连续行为交织的复杂状态变迁系统,形式化建模与验证是确保混成系统正确性和可靠性的重要途径。首先介绍一种混成ZIA形式规范;然后,基于建模语言MARTE建立扩展Object-Z的规范,即OZ-MARTE,该规范弥补了MARTE规范在形式化描述方面的不足,同时为了方便描述混成系统中连续动态行为属性,给出对混成系统中连续变量的描述转换规则,增强了MARTE对混成系统的描述能力;最后,给出OZ-MARTE规范到混成ZIA规范的转换方法,因此针对混成ZIA规范的验证技术同样适用于对MARTE模型进行形式化验证。     

构建度量区时序逻辑的时间自动机

在实时系统的形式验证中,为了直接验证带有明显时间约束的性质,选用了一种被广泛接受的(线性时间)实时时序逻辑——度量区时序逻辑来描述待验证的性质;提出了基于迁移的扩展时间B chi自动机;构建了度量区时序逻辑的基于迁移的扩展时间B chi自动机。这样扩展了已有实时系统模型检测工具的性质规范语言的表达能力,使其能直接处理和验证带有明显时间约束的性质。实现的工具表明,该算法有效且可行,并且显著地减少了结果自动机节点和迁移的数量,从而降低了结果自动机的大小,有利于进一步的模型检测过程。     

模型驱动的嵌入式系统设计安全性验证方法研究

基于模型的嵌入式系统安全性分析与验证方法是近年来在安全攸关系统工程领域中出现的一个重要研究热点。提出一种基于模型驱动架构的面向SysML/MARTE状态机的系统安全性验证方法,具体包括:构建了具备SysML/MARTE扩展语义的状态机元模型,以及安全性建模与分析语言AltaRica的语义模型GTS的元模型;然后建立了从SysML/MARTE状态机模型分别到时间自动机模型以及AltaRica模型的语义映射模型转换规则,并基于AMMA平台和时间自动机验证工具UPPAAL设计实现了对SysML/MARTE状态机的模型转换与系统安全性形式化验证的框架。最后给出了一个飞机着陆控制系统设计模型的安全性验证实例分析。     

一种实时系统时间约束验证方法研究

目前,能够对汽车电子领域中复杂嵌入式系统安全关键软件功能模和时间约束分析的方法尚在研究中,而这些系统作为实时控制系统,应该确保其具有准确的、可分析的时间行为。时钟约束规范语言CCSL是实时系统的标准描述语言中描述时钟约束的规范语言。采用CCSL规范表达式描述实时系统时间约束;设计了CCSL基本元素到时间自动机基本元素的转换规则;使用时间自用机验证工具UPPAAL对转换得到的自动机模型进行验证分析,验证实时系统是否满足相应的时间约束。     

基于模型转换的MARTE顺序图的形式化分析

作为一项新规范,MARTE有许多方面亟待完善.如何对依照MARTE设计的模型开展验证是待解决问题之一.对象管理组织提出用模型转换的方法将依照MARTE设计的模型(记为A)转换成另一种具有完备的验证方法和工具的形式化模型(记为B),然后对B进行验证和精化,以完成A的验证和精化工作.此思想面临的难题是如何保证B能够完整且准确地模拟A的行为.提出了形式化模型-TrS4SD,用来描述MARTE规范定义的带时间约束的顺序图的形式语义并在此基础上展开分析.首先给出顺序图的形式定义,把时阃变迁系统(TrS)扩充成TrS4SD,用TrS4SD描述顺序图的形式语义,最后对TrS4SD展开分析.这在一定程度上提高了设计阶段模型的正确性.通过一个实例说明从顺序图到TrS4SD的转化过程以及基于TTS4SD的验证方法.     

基于进程代数规约生成软件体系结构模型的方法

需求规约到软件体系结构(SA)模型的转换是软件工程领域的一个研究热点,UML-RT广泛用于实时系统软件体系结构建模,然而基于自然语言规约建立的UML-RT模型往往是不精确的,存在二义性,为了解决这一问题,需要赋予UML-RT模型形式化语义.进程代数是一种用来解决并发系统通信问题的形式化方法,具有精确的语法和语义,并且便于机器自动检验与验证.TCSP是进程代数CSP的实时扩展,适合于规约实时系统带有时间约束的行为.提出一种基于进程代数规约生成SA模型的方法.首先建立了自然语言规约到SA模型的转换框架;然后使用时间通信顺序进程(TCSP)描述实时系统需求规约,通过建立TCSP到UML-RT的转换机制,从而实现进程代数规约到SA模型的转换;最后通过一个实例来验证该方法在实时软件建模过程中的有效性.实验分析表明通过该方法建立的UML-RT模型能够从整体上提高实时系统SA设计的可信性.     

时间区间时序逻辑的判定性与表达能力

模型检测技术在实时系统验证中被广泛使用。离散时间区间时序逻辑满足性是可判定的,因而也是可模型检测的。连续时间域时间区间时序逻辑是否可模型检测,则并不清楚。约束时间域到非负实数,证明了其可满足性是不可判定的,但存在该逻辑的可判定子集,并发现了这样的子集。由于模型检测问题可归约为时序逻辑满足性判定问题,因此结果表明,时间区间时序逻辑不可模型检测,但其可判定子集可模型检测。     

带有时钟变量的线性时序逻辑与实时系统验证

为了描述实时系统的性质和行为,10多年来,各种不同的时序逻辑,如Timed Computation Tree Logic,Metric Interval Temporal Logic和Real-Time Temporal Logic等相继提出来.这些时序逻辑适于表示实时系统的性质和规范,但不适于表示实时系统的实现模型.这样,在基于时序逻辑的实时系统的研究中,系统的性质和实现通常是用两种不同的语言来表示的.定义了一个带有时钟变量的线性时序逻辑(linear temporal logic with clocks,简称LTLC).它是由Manna和Pnueli提出的线性时序逻辑在实时情况下的一个推广.LTLC既能表示实时系统的性质,又能很方便地表示实时系统的实现.它能在统一的语义框架中表示出从高级的需求规范到低级的实现模型之间的不同抽象层次上的系统描述,并且能用逻辑蕴涵来表示不同抽象层次的系统描述之间的语义一致性.LTLC的这个特点将有助于实时系统的性质验证和实时系统的逐步求精.     

基于DDS的发布/订阅中间件设计

基于OMG组织颁布的实时系统中数据分发服务最新标准设计了一个新的发布/订阅中间件,实现了分布式环境中以数据为中心的数据实时传输,解决了分布式实时系统中服务质量约束和单点失效等问题。提出一种全局数据空间管理策略,解决了通信节点动态增删问题。该模型与CORBA规范和其他发布/订阅模型相比,具有较好的灵活性、实时性、可扩展性和可靠性。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.