面向模型检验的UML状态机语义

UML状态机(SM)是UML中用来对系统各种元素的离散行为建模的图.它丰富的表示符号提供了强大的描述机制,但也降低了其结构的模块性,提高了对其分析验证的难度.模型检验是自动检验有限状态并发系统的技术.通过模型检验SM描述的不同系统元素的行为是否满足某些性质,能尽早发现设计中的错误.为了将模型检验技术应用于SM的验证,本文用kripke结构定义SM的操作语义.与已有的SM语义定义不同,本文考虑到了SM中包含的不确定因素,用kripke结构描述系统所有可能的演化轨迹.通过检验从SM翻译得到的kripke结构达到模型检验SM的目的.     

Process control software

This paper examines the nature of the software which is necessary so that a real-time computer may be used to control industrial processes. The general nature of a process control software system is discussed, and several methods for implementing such a system are examined. This paper is divided into several sections. First, the general structure of process control software systems is examined, and the programming problems associated with developing such a system are discussed. Then several tools for doing this programming are discussed, including problem-oriented languages, "fill-in-the-blank programming systems," procedural programming languages, and the operating systems which are used to tie the different portions of a process control system together. This paper closes with a dicussion of future trends in process control software, and recent activities in developing software standards. It will be assumed that the reader is generally familiar with software with at least a passable knowledge of FORTRAN programming.     

Model-integrated mechatronics - toward a new paradigm in the development of manufacturing systems

The traditional approach for the development of manufacturing systems considers the constituent parts of the system, i.e., mechanical, electronic, and software, to be developed independently and then integrated to form the final system. This approach is being criticized as inappropriate for the complexity and the dynamics of today's systems. This paper proposes an architecture that promotes model integration not only for implementation space artifacts but also in artifacts of the early analysis and design phases of the development process. The proposed architecture, which promotes reuse and significantly decreases development and validation time, is at the heart of a new paradigm called model-integrated mechatronics (MIM). MIM applies domain-specific modeling languages for the concurrent engineering of mechanical, electronic and software components of mechatronic systems. It simplifies the integrated development process of manufacturing systems by using as basic construct the mechatronic component. The MIM paradigm was utilized to define "Archimedes," a system platform that supports the engineer through a methodology, a framework, and a set of tools to automate the development process of agile mechatronic manufacturing systems.     

System Prototype and Verification Using Metamodel-Based Transformations

Mapping domain-specific languages' core concepts into the concurrent object-oriented Petri nets formal specification language provides users with the semantics necessary for developing prototypes for these DSLs. Different knowledge domains demand different types of support from software languages. Domain engineers often use domain-specific languages to overcome this problem. DSLs are difficult to design, implement, and maintain and are often less efficient than hand-coded software. To address some of these problems, we propose transforming a DSL into the concurrent object-oriented Petri nets formalism. The DSL metamodel serves as the transformation's starting point. The transformation represents the semantic mapping between the DSL and CO-OPN. We aim both to provide a formally defined semantics for the DSL and, because we integrate CO-OPN in a framework, to provide the functionalities that allow model verification and fast prototype generation for the DSL     

基于目标语义特征的图像检索系统

为克服当前基于内容的图像检索技术中低级特征无法准确全面地描述高级语义的问题,该文设计和实现了一个基于目标高级语义特征的检索系统。该系统利用了一个多级图像描述模型将语义特征结合到图像检索技术中。该图像描述模型通过在不同层次上对图像内容进行分析和描述,实现了从低级特征到高级语义的过渡。在此模型的基础上还研究了相应的检索机制和反馈技术。该系统的检索机制定位于图像中目标的语义内容,与传统的图像检索系统相比更接近人对图像内容的理解,从而使检索过程更简便,检索效率也得到很大提高。基于目标描述的自适应相关反馈可针对不同用户的不同需求给出相应的检索方案,从而使检索结果得到优化。     

Heterogeneous Simulation—Mixing Discrete-Event Models with Dataflow

This paper relates to system-level design of signal processing systems, which are often heterogeneous in implementation technologies and design styles. The heterogeneous approach, by combining small, specialized models of computation, achieves generality and also lends itself to automatic synthesis and formal verification. Key to the heterogeneous approach is to define interaction semantics that resolve the ambiguities when different models of computation are brought together. For this purpose, we introduce a tagged signal model as a formal framework within which the models of computation can be precisely described and unambiguously differentiated, and their interactions can be understood. In this paper, we will focus on the interaction between dataflow models, which have partially ordered events, and discrete-event models, with their notion of time that usually defines a total order of events. A variety of interaction semantics, mainly in handling the different notions of time in the two models, are explored to illustrate the subtleties involved. An implementation based on the Ptolemy system from U.C. Berkeley is described and critiqued.     

CoWare—A design environment for heterogeneous hardware/software systems

This paper addresses CoWare: an environment for design of heterogeneous systems on chip. These systems are heterogeneous both in terms of specification and implementation. CoWare is based on a communicating processes data-model which supports encapsulation and refinement and makes a strict separation between functional and communication behaviour. Encapsulation enables the reuse of existing specification and design environments (languages, simulators, compilers). Refinement provides for a consistent and integrated path from specification to implementation. The design steps that will be addressed include: system specification, simulation at various abstraction levels, data path synthesis, communication refinement and hardware/software co-design. A spread-spectrum based pager system serves to illuminate the design process in the CoWare environment.     

Ontologies: giving semantics to network management models

The multiplicity of network management models may imply in some scenarios the use of multiple management information languages defining the resources to be managed. Each language has a different level of semantic expressiveness, which is not easily measurable. Also, these management information models cannot be easily integrated due to the difficulty of translation of the semantics they contain. The article proposes the use of ontologies as a new approach to improving the semantic expressiveness of management information languages. Ontologies are currently used, for instance, to provide Web pages and Web services the semantics they usually lack (known today as the semantic Web). Applying ontologies to management information languages can also be useful for integration of information definitions specified by different management languages and adding behavior information to them.     

Interlanguage Communication Synthesis for Heterogeneous Specifications

Nowadays the design of complex systems requires the cooperation of several teams belonging to different cultures and using different languages. It is necessary to dispose of new design and verification methods to handle multilanguage approaches. This paper presents an approach for the interlanguage communication synthesis of heterogeneous specifications. The system is represented by a set of interconnected subsystems specified in different languages with different concepts, different interface types, different communication schemes and some of them can even be IP modules. The subsystems exchange data through abstract communication channels. The objective is to refine the abstract communication channels into an implementation. The result is a set of interconnected processors communicating through signals, buses and dedicated components. An example illustrates the usefulness of this approach for the design of an adaptive speed control system that was described in SDL and Matlab.     

Reprogrammable Platforms for High-Speed Data Acquisition

Complex embedded systems that do not target mass marketsoften have design and engineering costs that exceed production costs. Oneexample is the triggering and data acquisition system (DAQ) integrated intohigh-energy physics experiments. Parameterizable and reprogrammable architecturesare natural candidates as platforms for specialized embedded systems likehigh-speed data acquisition systems. In order to facilitate the design ofspecialized embedded systems, design strategies and tools are needed thatgreatly increase the efficiency of the design process. End-user programmabilityof reprogrammable platforms is essential, because system designers, withouttraining in low-level programming languages, are required to change the basedesign, compare designs, and generate configuration data for the reprogrammableplatforms. This paper presents a methodology for designing and evaluatinghigh-speed data acquisition systems using reprogrammable platforms.     

Temporal representation and reasoning for workflow in engineeringdesign change review

Workflow management, which is concerned with the coordination and control of business processes using information technology, has grown from its origins in document routing to include the automation of process logic in business process reengineering. Workflow also has a strong temporal aspect; activity sequencing, deadlines, routing conditions, and scheduling all involve the element of time. Temporal expert systems, which use knowledge-based constructs to represent and reason about time, can be used to enhance the capabilities of workflow software. This paper presents a temporal expert system workflow component for tracking engineering design changes. The authors use Allen's theory of temporal intervals in their model to enhance the decision-making, timing, and routing activities in a workflow application. They test the model using information from a “real-world” engineering design situation and suggest further research opportunities     

基于端到端的多语种语音识别研究

端到端语音识别模型无需发音词典进行训练,可以大幅降低开发新语种语音识别系统的负担。本文利用端到端模型的这一优势,建立了一种语种无关的端到端多语种语音识别系统。该模型使用基于字符的建模方法进行训练,同时构建多语种输出符号集,使其包括所有目标语言中出现的字符。模型训练生成单一模型,其网络参数为所有语种共享。在OLR竞赛提供的10个语种数据集上,相较于单语种语音识别系统,本文提出的多语种语音识别系统在所有语言上的表现都更加优秀。      

Variance of system-reliability estimates with arbitrarily repeatedcomponents

A model is developed to determine the variance of system reliability estimates and to estimate confidence intervals for series-parallel systems with arbitrarily repeated components. For these systems, different copies of the same component-type are used several or many times within the system, but only a single reliability estimate is available for each distinct component-type. The single estimate is used everywhere the component appears in the system design, and component estimation-error is then magnified at the system-level. The "system-reliability estimate" variance and confidence intervals are derived when the number of component failures follow the binomial distribution with an unknown, yet estimable, probability of failure. The "system-reliability estimate" variance and confidence intervals are obtained by expressing system reliability as a linear sum of products of higher order moments for component unreliability. The generating function is used to determine the moments of the component-unreliability estimates. This model is preferable for many system reliability estimation problems because it does not require independent component and subsystem reliability estimates; it is demonstrated with an example     

面向对象程序设计语言研究现状

面向对象程序设计已成为一种重要的程序设计范型，被广为接受和使用，数量众多的程序设计语言提供了对这种范型的支持，本文综述了面向对象程序设计语言的研究现状，着重讨论了如下几方面的问题：语义研究、类型系统、语言特性、分布性、语言的变种及Ｓｍａｌｌｔａｌｋ等。     

High-level protocols

High-level protocols (HLP's) are the high-level languages of distributed systems. In a resource-sharing network, HLP's link processes working on a conmmn application. The design of an HLP is decomposed into three components: language, coding, and transport. The language expresses the commands and data passed between processes. It is designed to provide standardization and device independence, in order to use a small number of HLP's to address a range of applications implemented on a variety of computer systems. Coding converts the language into digital messages. Finally, a transport system is used to transmit the messages from one process to another-experience with HLP's has shown that different HLP's require different transport behaviors. This paper describes some examples of HLP's (ARPA network voice and graphics protocols), and argues that modern techniques for expressing structure and control in programming languages should be applied to analogous problems in communication among application processes in a network.     

Analysing Internet Software Retrieval Systems: Modeling and Performance Comparison

Nowadays, there exist web sites that allow users to retrieve and install software in an easy way. The performance of these sites may be poor if they are used in wireless networks; the reason is the inadequate use of the net resources that they need. If these kinds of systems are designed using mobile agent technology the previous problem might be avoided. In this paper, we present a comparison between the performance of a software retrieval system especially designed to be used in a wireless network and the performance of a software retrieval system similar to the well-known Tucows.com web site. In order to compare performance, we make use of a software performance process enriched with formal techniques. The process has as important features that it uses UML as a design notation and it uses stochastic Petri nets as formal model. Petri nets provide a formal semantics for the system and a performance model.