A methodology for design, test, and evaluation of real-time systems

This article presents a methodology that is suitable for use as part of either a prototyping approach or a component-reuse approach. This methodology integrates modeling and simulation as well as developmental and operational testing over the life cycle. The type of systems or components we address operate in real time. Designing and testing real-time systems involves the use of multiple processors and communication links. The real-time system itself can run on a single processor or multiple processors. Even when the system runs on a single processor, the test and evaluation environment uses multiple processors. If the evaluation environment were hosted on the system processor, system performance would be affected. For ease of exposition, we focus on sensor systems; the methodology described is widely applicable to other kinds of systems. We use two examples (a space-borne navigation system and an interferometer system) to describe the methodology and show how it can be used. This methodology can reduce project costs and shorten schedules because it requires performance evaluation and integration testing early, when problems are generally easier and less costly to correct     

Matching, linear systems, and the ball and beam

A recent approach to the control of underactuated systems is to look for control laws which will induce some specified structure on the closed loop system. In this paper, we describe one matching condition and an approach for finding all control laws that fit the condition. After an analysis of the resulting control laws for linear systems, we present the results from an experiment on a nonlinear ball and beam system.     

Managing, Modeling, and Visualizing High-dimensional Spatio-temporal Data in an Integrated System

An approach to an interoperable object-oriented GIS-framework for atmospheric modeling (AtmoGIS), which can be used to implement integrated information systems, is presented. The consideration of user-workflows leads to the specification of the projected system. Using an object-oriented approach, the system is based on a spatio-temporal database management system, a mesoscale model and an environment for scientific visualization.     

Risk modeling in distributed, large-scale systems

Risk is inherent in distributed, large-scale systems. The paper explores the challenges of risk modeling in such systems, and suggests a risk modeling approach that is responsive to the requirements of complex, distributed, large-scale systems. An example of the use of the approach in the marine transportation system is given. The paper concludes with a discussion of limitations of the approach and of future work     

关于非线性系统的对程性、可达性与可控性*

本文讨论对称及广义对称非线性系统的可达性与可控性。文中证明了如果广义对称系统在一点的邻域可控,那么系统在包含该点群作用轨道的一个开集上是可控的。利用广义对称性还给出了控制律的原则算法。对于对称系统,给出了可控性的充要条件。     

Overlapping decompositions, expansions, contractions, and stabilityof hybrid systems

Inclusion and extension principles are defined and studied for hybrid systems. The controller design problem for hybrid systems is then considered within the framework of the extension principle. It is shown that if the extension principle is used, then any controller designed in the expanded spaces is contractible to the original spaces for implementation. The stability of hybrid systems is also considered. A number of definitions of stability for hybrid systems are given and it is shown that if a system, which includes another system, is stable, then the included system is also stable. Furthermore, it is shown that, if a controller designed for the expanded system achieves stability, then the contracted controller also achieves stability for the original system. Decentralized controller design with overlapping decompositions is also discussed within the framework of extension. An example is provided to illustrate the proposed approach     

MAPIS,a multi-agent system for information personalization

In the domain of multi-user and agent-oriented information systems, personalized information systems aim to give specific and customized responses to individual user requests. In addition to the ability to analyze user needs and to retrieve, understand and act on distributed data that is offered by any agent-oriented system, multi-agent systems also offer interesting possibilities for interaction, particularly with regard to information sharing and task coordination. Our approach exploits these interactive possibilities in order to make the system capable of personalizing information. In addition, reusable models at both the social and individual levels were chosen for this approach in order to facilitate subsequent information system design. With these two ideas in mind, several models of agent interaction (social) and the internal activity cycles (individual) have been proposed with the aim of creating a multi-agent system for information personalization.     

ABC:基于体系结构、面向构件的软件开发方法

基于构件的软件复用和开发被认为是提高软件开发效率和质量的有效途径,并在分布式系统中得到了广泛的应用.但是,目前的软件构件技术主要还是着眼于构件实现模型和运行时互操作,缺乏一套系统的方法以指导整个开发过程.近年来,以构件为基本单元的软件体系结构研究取得了较大的发展.它通过对软件系统整体结构和特性的描述,为面向构件的软件开发提供了一个自顶向下的途径.介绍了一种以软件体系结构为指导,面向构件的软件开发方法,试图为基于构件的软件复用提供一种有效的解决方案.这种方法主要是将软件体系结构引入到软件开发的各个阶段,作为系统开发的蓝图,利用工具支持的自动转换机制缩小从高层设计到实现的距离,而后在构件平台的运行支持下实现自动的系统组装生成.     

Integrating vision modules: stereo, shading, grouping, and linelabeling

It is generally agreed that individual visual cues are fallible and often ambiguous. This has generated a lot of interest in design of integrated vision systems which are expected to give a reliable performance in practical situations. The design of such systems is challenging since each vision module works under a different and possibly conflicting set of assumptions. We have proposed and implemented a multiresolution system which integrates perceptual organization (grouping), segmentation, stereo, shape from shading, and line labeling modules. We demonstrate the efficacy of our approach using images of several different realistic scenes. The output of the integrated system is shown to be insensitive to the constraints imposed by the individual modules. The numerical accuracy of the recovered depth is assessed in case of synthetically generated data. Finally, we have qualitatively evaluated our approach by reconstructing geons from the depth data obtained from the integrated system. These results indicate that integrated vision systems are likely to produce better reconstruction of the input scene than the individual modules     

Specification, decomposition and agent synthesis for situation-aware service-based systems

Service-based systems are distributed computing systems with the major advantage of enabling rapid composition of distributed applications, such as collaborative research and development, e-business, health care, military applications and homeland security, regardless of the programming languages and platforms used in developing and running various components of the applications. In dynamic service-oriented computing environment, situation awareness (SAW) is needed for system monitoring, adaptive service coordination and flexible security policy enforcement. To greatly reduce the development effort of SAW capability in service-based systems and effectively support runtime system adaptation, it is necessary to automate the development of reusable and autonomous software components, called SAW agents, for situation-aware service-based systems. In this paper, a logic-based approach to declaratively specifying SAW requirements, decomposing SAW specifications for efficient distributed situation analysis, and automated synthesis of SAW agents is presented. This approach is based on AS³ calculus and logic, and our declarative model for SAW. Evaluation results of our approach are also presented.     

Focusing and polarization in linear,intuitionistic, and classical logics

A focused proof system provides a normal form to cut-free proofs in which the application of invertible and non-invertible inference rules is structured. Within linear logic, the focused proof system of Andreoli provides an elegant and comprehensive normal form for cut-free proofs. Within intuitionistic and classical logics, there are various different proof systems in the literature that exhibit focusing behavior. These focused proof systems have been applied to both the proof search and the proof normalization approaches to computation. We present a new, focused proof system for intuitionistic logic, called LJF, and show how other intuitionistic proof systems can be mapped into the new system by inserting logical connectives that prematurely stop focusing. We also use LJF to design a focused proof system LKF for classical logic. Our approach to the design and analysis of these systems is based on the completeness of focusing in linear logic and on the notion of polarity that appears in Girard’s LC and LU proof systems.     

Multimachine power systems: Stability, decomposition, and aggregation

A new approach is proposed for transient stability analysis of interconnected power systems, which is based upon the concept of vector Lyapunov functions and the decomposition-aggregation method. The approach results in an exact procedure for computation of stability region estimates which are expressed explicitly in terms of system parameters. More refined models of the subsystems can be readily accommodated by the new approach. In particular, the transfer conductances are included in the present study, a feature which is almost exclusively missing in transient stability analysis of multimachine systems by Lyapunov's method.     

Organization-based agent-oriented programming: model, mechanisms, and language

An increasing number of social computational systems consist of a great amount of autonomous entities and operate in highly dynamic and unpredictable environments. To construct such systems needs to seek high-level abstraction to manage the complexity of the systems and novel mechanism to support their characteristics, i.e., dynamism and flexibility. Agent-oriented programming (AOP) is considered as a potential paradigm for developing such systems by exhibiting a number of characteristics, such as autonomy, flexibility, social ability, etc. However, current researches on AOP mainly focus on the construction of multi-agent system (MAS) with theory and language facilities inspired from artificial intelligence (AI) and distributed AI, seldom considering and integrating the proven principles and practices of programming and software engineering. Moreover, abstractions and mechanism based on AI are inadequate for developing dynamic and flexible MAS in open environment. This paper proposes a novel AOP approach, namely Oragent, for constructing and implementing dynamic and flexible systems. From a software engineering perspective, Oragent integrates organizational concepts and mechanism into AOP language, and support the dynamism and flexibility with explicit primitives. The proposed approach consists of a programming model and a corresponding programming language. This paper presents the syntax and formal operational semantics of Oragent language, and studies a case to demonstrate our approach.     

Work-arounds, make-work, and kludges

Paradigms are often defined partly in terms of what they are not, or in terms of what they are reacting against. The paradigm of human-centered computing is no exception. We discuss about a user-hostile system. We decided that the terms kludge and work-around, and also the related concept of make-work, has yet to be clearly defined for the intelligent systems community. Human-centered systems are different from user-hostile systems as well as from systems based on a designer-centered approach. We try to clarify the senses of these three terms and suggest ways we might study work-around, make-work, and kludges as an integral part of human-computer systems-rather than as embarrassing necessities that are best swept under the computing research rug.     

A generic, object-oriented case-knowledge representation scheme, and its integration into a wider information management scenario

Abstract: A knowledge base management system (KBMS) realises a combination of techniques found in database management systems and knowledge-based systems. At the data model and knowledge representation level, many systems of this kind constitute a marriage of the relational data model and the rule-based reasoning. Experience has shown that either approach is restricted in the way it can express the demanding information and knowledge structures required for applications like decision support systems. Two new technologies offer an exciting new integrated approach to knowledge management. Object-oriented database management systems (OODBMS) provide an object model that supports powerful abstraction mechanisms to facilitate the modelling of highly structured information. Whereas case-based reasoning (CBR) systems are knowledge bases which organise their capabilities around a memory of past cases and the notion of similarity. Both types of system are built upon two fundamental concepts: 1) the retrieval of entities with potentially complex structure, called objects in the former, and cases in the latter type of system; 2) the organisation of those entities in collections with common characteristics. In an OODBMS such collections are termed extents, and in CBR they are usually called categories. In either system, the conceptual meta notion to represent both, objects as well as extents, and cases as well as categories, is the class.
Revolving around a Conceptual Case Class and extending a standard object model, this paper proposes a novel and general approach to represent case-knowledge and to build KBMSs. The work presented here is a spin-off of the design of an object query language within the ESPRIT project Lynx.     

Estimation of states,faults and unknown disturbances in non-linear systems

In this paper, we extend existing theory on non-linear unknown input observer design to a wider class of non-linear systems where the systems are subject to unknown input and output disturbances and experience faults. The approach used is to decouple the faults and unknown disturbances from the rest of the system through a series of transformations on state and output equations. Once total disturbance decoupling is achieved, an appropriate observer for the disturbance free part of the non-linear system is proposed and designed. The designed observer is, subsequently, used for estimation of unknown inputs, outputs, and fault signals. Two examples are given for illustration.     

An approach to improve the performance of adaptive predictive control systems: theory,simulations and experiments

In this paper an approach to improve the overall performance of indirect adaptive control systems tailored for non-linear stable plants is presented. The approach involves a commutation of a linear time-varying robustness filter in the feedback path of the control loop in synchronization with an adaptive controller. The algorithm is framed in the celebrated IMC structure for predictive control systems. It can automatically suit to structural changes in the system as order and dead-time, and can deal with plants with zero dynamics. The convergence and stability of the system is analysed in details. It is shown through numeric simulations and experimentation on a heat exchanger with cooling system, that undesired transients due to abrupt and significative changes in the dynamics can be efficiently damped down by the developed control algorithm, achieving a high-quality performance in steady state.     

The PROTEVS approach: A short presentation of background,principles and methods

Prototyping is not a new approach to computer-based information system development. It is just one technique among many used in system design. What might be new is for what purpose prototyping is used. The purpose could be to achieve a more user controlled system development and to give the future users a tool that will enable them to fully participate in not only the work with requirements specifications, but also in the actual systems design and organisational change. This paper describes a working model of an approach-the PROTEVS model-in which it is recommended that the future system users design their own prototype systems. The prototypes may act as both requirements specifications and solutions for actual change. This alternative approach aims to offer a basis for new ways of action for future users as participants in the design, evaluation, and change of a workplace. A suitable environment for the approach to act within is also described—a local design shop.     

The reliability estimation, prediction and measuring of component-based software

Reliability is a key driver of safety-critical systems such as health-care systems and traffic controllers. It is also one of the most important quality attributes of the systems embedded into our surroundings, e.g. sensor networks that produce information for business processes. Therefore, the design decisions that have a great impact on the reliability of a software system, i.e. architecture and components, need to be thoroughly evaluated. This paper addresses software reliability evaluation during the design and implementation phases; it provides a coherent approach by combining both predicted and measured reliability values with heuristic estimates in order to facilitate a smooth reliability evaluation process. The approach contributes by integrating the component-level reliability evaluation activities (i.e. the heuristic reliability estimation, model-based reliability prediction and model-based reliability measuring of components) and the system-level reliability prediction activity to support the incremental and iterative development of reliable component-based software systems. The use of the developed reliability evaluation approach with the supporting tool chain is illustrated by a case study. The paper concludes with a summary of lessons learnt from the case studies.