一种弱耦合电子商务模型

提出了一种适合大型软件系统耦合性分析的系统耦合度模型SCD。在Web Services基础上，构建了一个开放的、可扩展的、弱耦合应用程序架构。以电子商务模型的体系架构作为研究对象，按照Web Service方式初步实现了电子商务模型的所有重要环节，、实现了电子商务系统在Internet之上的弱耦合集成。     

Latent benefits of consensus processes

The history of technology is the history of the birth, weaning and (mostly) death of ideas. Action based on consensus requires a thorough understanding of all significant opposing points of view. Standardization deliberations employ formal consensus processes and (in the United States) are the most common forums to do so. But in a larger sense, consensus processes are central to scientific and technological progress. The role of consensus processes, and of standardization deliberations, in progress at the state-of-the-art is discussed.     

New methods for interaction analysis of complex processes using weighted graphs

The selection of the structure of a controller in large scale industry processes usually requires extensive process knowledge. The aim of this paper is to report new results on recently suggested methods for the analysis of complex processes. These methods aid the designers in comprehending a process by representing structural and functional relationships from actuators and process disturbances to measured or estimated variables. The methods are formulated in a flexible framework based on graph theory, which can also be used for closed-loop analysis. Additionally, the sensitivity of the methods to scaling and time delays are discussed and resolved. It is also proposed how filtering can be used to restrict the analysis to a frequency region of interest.The feasibility of the methods is shown by the use of three case studies. A quadruple tank process is used to exemplify the methods and their use. Then the methods are applied on a real-life process, the stock preparation plant of a pulp and paper mill. The third study case analyzes a previously published example in closed loop.It is shown that the methods can be used to take efficient decisions on decentralized and sparse control structures, as well as assessing the channel interactions in a closed-loop system.     

Fail-Awareness: An Approach to Construct Fail-Safe Systems

We present a framework for building fail-safe hard real-time applications in timed asynchronous distributed systems subject to communication partitions and performance, omission, and crash failures. Most distributed systems built from commercial-off-the-shelf (COTS) processor and communication services are subject to such partitions because their COTS components do not provide hard real-time guarantees. Also custom designed systems can be subject to partitions due to unmaskable link or router failures. The basic assumption behind our approach is that each processor has a local hardware clock that proceeds within a linear envelope of real-time. This allows one to compute an upper bound on the actual delays incurred by a particular processing sequence or message transmission. Services and applications can use these computed bounds to detect when they cannot guarantee all their standard properties because of excessive delays. This allows an application to be fail-aware, that is, to detect when it cannot guarantee all its safety properties and in particular, to detect when to switch to a fail-safe mode.     

Markov跳变系统的非同步事件触发耗散容错控制

本文主要研究一类具有执行器故障的Markov跳变系统的非同步事件触发耗散容错控制问题.通过引入非同步事件触发器来降低传感器的采样数据传输频率,从而降低通信消耗.采用两个独立的隐Markov模型分别描述触发器、控制器与原系统之间的非同步现象.在此框架下,基于Lyapunov稳定性和耗散理论,得到了闭环控制系统在执行器存在故障的情况下随机稳定并严格耗散的充分条件.并借助矩阵不等式变换技术给出了触发器和控制器矩阵参数的求解方法,实现了触发器和控制器的协同设计.最后,通过仿真研究验证了所提出的设计方法的有效性.     

实时产生式系统

产生式系统是一种重要的人工智能程序设计语言,但却比较难于应用到实时领域之中.本文在分析其在实时应用方面两个主要不足的基础上,对实现实时产生式系统的几种可能途径与方法做了较为深入的探讨.     

Discrepancy based control of particulate processes

This article deals with a new approach to particulate process control. The model system under investigation, the continuous fluidized bed spray granulation with external product classification, is described by a nonlinear partial integro-differential equation, the population balance equation for the particle size distribution. This process exhibits interesting dynamical behavior, i.e. a change of the stability behavior and the occurrence of limit cycles. In addition, the zero dynamics with respect to moment measurements frequently used in practice are unstable in certain parameter regions. In order to stabilize these types of systems in this contribution the use of a generalized distance measure, the discrepancy, is proposed. Applying, the associated stability theory, i.e. stability theory with respect to two discrepancies, a stabilizing control law can be derived. One of the main advantages of the proposed discrepancy based control method is that no model reduction is required.     

Voltage-Clock Scaling for Low Energy Consumption in Fixed-Priority Real-Time Systems

Power and energy constraints are becoming increasingly prevalent in real-time embedded systems. Voltage-scaling is a promising technique to reduce energy and power consumption: clock speed tends to decrease linearly with supply voltage while power consumption goes down quadratically. We therefore have a tradeoff between the energy consumption of a task and the speed with which it can be completed. The timing constraints associated with real-time tasks can be used to resolve this tradeoff. In this paper, we present two algorithms for voltage-scaling. Assuming that a processor can operate in one of two modes: high voltage and low voltage, we show how to schedule the voltage settings so that deadlines are met while reducing the total energy consumed. We show that significant reductions can be made in energy consumption.     

Communicating parallel processes

By considering the problem of an event timer it is shown that the commonly available synchronizing facilities (monitors, CSP, distributed processes) are not able to always satisfactorily model the requirements of several processes which must run in parallel and which have to communicate with each other. The problem is discussed in general terms which show that what is required are new concepts for communicating processes. The synchronization facilities proposed are augmented to incorporate the concept of process scheduling directly from a process. This ensures that proper scheduling of process components can take place. The new mechanism is then applied to a number of the standard problems. It is also shown that the use of nondeterminacy in current facilities is probably not required and is, in fact, for many applications, a positive disadvantage.     

Integrating primary ocular processes

The study of active vision using binocular head-eye systems requires answers to some fundamental questions in control of attention. This paper presents a cooperative solution to resolve the ambiguities generated by the processes engaged in fixation. We suggest an approach based on integration of these processes, resulting in cooperatively extracted unique solutions. The discussion begins by looking at biological vision. Based on this discussion, a model of integration for machine vision is suggested. The implementation of the model on the KTH-head — a head-eye system simulating the essential degrees of freedom in mammalians — is explained, and in this context the primary processes in the head-eye system are briefly described. The major stress is put on the idea that the rivalry processes in vision in general, and the head's behavioural processes in particular, results in a reliable outcome. As an experiment, the ambiguities raised by fixation at repetitive patterns is tested; the cooperative approach proves to handle the problem correctly and find a unique solution for the fixation point dynamically and in real-time.     

Visualizing processes on the web

In this paper, we describe 3WPS, a framework to build distributed systems that are able to monitor and interact with a process through a 3D interface that is accessible via the World Wide Web (WWW). The 3WPS is easily configurable, easily adaptable to different processes with high reuse of its software components and its distributed architecture leverages on off-the-shelf components of the WWW infrastructure such as Java applets and Virtual Reality Modeling Language (VRML) browsers. We describe the characteristics of 3WPS framework by mainly focusing on the issue of programmability and by contextually providing an example tour of its usage.     

ISE-optimal nonminimum-phase compensation for nonlinear processes

This work concerns the optimal regulation of single-input–single-output nonminimum-phase nonlinear processes. The problem of calculation of an ISE-optimal, statically equivalent, minimum-phase output for nonminimum-phase compensation is formulated using Hamilton–Jacobi theory and the normal form representation of the nonlinear system. A Newton–Kantorovich iteration is developed for the solution of the pertinent Hamilton–Jacobi equations, which involves solving a Zubov equation at each step of the iteration. The method is applied to the problem of controlling a nonisothermal CSTR with Van de Vusse kinetics, which exhibits nonminimum-phase behaviour.     

Stabilisation of a class of positive switched nonlinear systems under asynchronous switching

This paper addresses the stabilisation problem for a class of positive switched nonlinear systems under asynchronous switching, which means that the switches between the candidate controllers and the system modes are not synchronous. The continuous and discrete cases are considered respectively. Sufficient conditions are firstly provided for the existence of the asynchronous switching controllers to guarantee the closed-loop system to be positive and exponentially stable, and the corresponding admissible switching signals are presented. As a special case, the stabilisation results for positive switched linear systems under asynchronous switching are provided accordingly. Finally, two numerical examples are given to illustrate the effectiveness of the proposed methods.     

Reset control of integrating plus dead time processes

This work develops a tuning method for a reset compensator and an integrating plus dead time system. The reset compensator consists of a proportional integral compensator plus a Clegg integrator (PI+CI), and is equipped with a variable band resetting law, which allows to reduce the harmful effect of time-delay, and a switching reset ratio that obtains a superior performance in comparison with a well-tuned PI compensator. This work exposes a simple tuning rule for setting all the parameters of the PI+CI compensator with the aim of improving both setpoint tracking and load disturbance rejection. A case study is analyzed by simulation, discussing both performance and robustness of several PI+CI and PI compensators. Finally, an experiment of liquid level control shows the advantages of the proposed reset compensator.     

Asynchronous consensus of continuous-time multi-agent systems with intermittent measurements

This article is concerned with asynchronous consensus problems of continuous-time second-order agents with fixed topology and time-varying delays. It is assumed that each agent obtains the measurements of its states relative to its neighbours only at discrete times and the discrete times of each agent are independent of the others'. It is proven that the asynchronous consensus is equivalent to the global asymptotic stability of a time-varying discrete-time system with delays. Furthermore, a sufficient condition for asynchronous consensus is established in virtue of the Lyapunov's direct method. Simulations are performed to validate the theoretical results.     

Relaxation and well-posedness of nonlinear optimal processes

An optimal control problem with perturbed nonlinear dynamics and perturbed state constraints is considered. The equivalence between performance well-posedness and regularity in the sense of relaxation is studied.     

Anticipatory network models of multicriteria decision-making processes

In this article, we will investigate the properties of a compromise solution selection method based on modelling the consequences of a decision as factors influencing the decision making in subsequent problems. Specifically, we assume that the constraints and preference structures in the (k?+?1)st multicriteria optimisation problem depend on the values of criteria in the k-th problem. To make a decision in the initial problem, the decision maker should take into account the anticipated outcomes of each linked future decision problem. This model can be extended to a network of linked decision problems, such that causal relations are defined between the time-ordered nodes. Multiple edges starting from a decision node correspond to different future scenarios of consequences at this node. In addition, we will define the relation of anticipatory feedback, assuming that some decision makers take into account the anticipated future consequences of their decisions described by a network of optimisers ? a class of information processing units introduced in this article. Both relations (causal and anticipatory) form a feedback information model, which makes possible a selection of compromise solutions taking into account the anticipated consequences. We provide constructive algorithms to solve discrete multicriteria decision problems that admit the above preference information structure. An illustrative example is presented in Section 4. Various applications of the above model, including the construction of technology foresight scenarios, are discussed in the final section of this article.     

Asynchronous Distributed Algorithms for Heading Consensus of Multi‐Agent Systems with Communication Delay

In this paper, we propose two asynchronous distributed protocols for the heading consensus of a multi‐agent group which cannot access a global coordinate system and a global time. Both the leaderless and leader‐following cases are addressed, and inter‐agent communication delay is taken into account. It is proved, under some standard connectivity assumptions, that our leaderless algorithm ensures the heading consensus provided the initial headings are not balanced; and the leader‐based algorithm guarantees the global heading consensus.