Distributed real-time embedded systems: Recent advances, future trends and their impact on manufacturing plant control

Real-time and embedded systems have historically been small scale. However, advances in microelectronics and software now allow embedded systems to be composed of a large set of processing elements, and the trend is towards significant enhanced functionality, complexity, and scalability, since those systems are increasingly being connected by wired and wireless networks to create large-scale distributed real-time embedded systems (DRES). Such embedded computing and information technologies have become at the same time an enabler for future manufacturing enterprises as well as a transformer of organizations and markets. This paper discusses opportunities for using recent advances in the DRES area in the deployment of intelligent, adaptive, and reconfigurable manufacturing plant control architectures.     

Emergence of auto-catalytic structure in stochastic self-reinforcing reaction networks

We consider a chemical reaction network model in which some of the reactions are stochastic and depend on past history. In this chemical reaction network, we found the emergence of autocatalytic sets (ACS) and complex dynamics in which ACS are repeatedly created and destroyed. This work was presented in part at the 7th International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18, 2002     

Intelligent control for urban traffic systems

This paper proposes a hierarchically intelligent control procedure to resolve certain aspects of the urban traffic management problem. Three levels of the hierarchical system: the linguistic organization, the coordinator, and the on-line controller are responsible, respectively, for the management of traffic in city, neighborhood, and single intersection. Traffic situations are partitioned into five different categories, ranging from sparse to immobile traffic. For each category (except the immobile traffic which is not probed in this paper) a suitable control scheme is introduced. The control at the lowest level, single intersection, will be exerted by optimizing an assigned subgoal. Each coordination level will manage the interaction among the single intersections within its jurisdiction. A learning algorithm is incorporated at this level in order to reduce considerably the need for extensive a priori numerical computations.     

基于变迁系统的反应型控制系统建模与分析

文中通过对基本变迁系统进行相应的扩充，分别给并发、实时及混成等3个不同轴象层次反应型控制系统的计算模型，并分析它们各自不同的特点。     

Expert support systems design issues

Expert support systems (ESSs) promise valuable support to decision-makers in business settings where a number of complex and interacting decisions must be accommodated. Even though the proliferation of ESSs in business has been limited, the issues involved in designing such systems need to be addressed so that development resources are well utilized and the end product is successful. This paper addresses the following questions: What are the factors that affect the successful design of an ESS? And how do these factors affect the design process? These factors are identified by considering factors that are relevant to MIS development and how they relate to the new technology of expert systems. A prototype ESS is used to illustrate the issues addressed in this paper.     

Positive invariance, monotonicity and comparison of nonlinear systems

In this paper, the interrelation between positive invariance, monotonicity and comparison of iterated nonlinear systems defined in partially ordered sets is studied. First, necessary and sufficient conditions guaranteeing the positive invariance of sets defined by relations of the form v(x)≤w with respect to nonlinear systems are established. Then, various characterizations of monotone nonlinear systems are developed and a connection between positive invariance and monotonicity is established. Finally, necessary and sufficient conditions for a, not necessarily monotone, nonlinear system to be a comparison system are established. No specific algebraic structure is necessary for developing the main results of this work. Numerical examples illustrating the applicability of all these results to the case of discrete-time dynamical systems are also given.     

Hybrid expert systems: A survey of current approaches and applications

This paper is a statistical analysis of hybrid expert system approaches and their applications but more specifically connectionist and neuro-fuzzy system oriented articles are considered. The current survey of hybrid expert systems is based on the classification of articles from 1988 to 2010. Present analysis includes 91 articles from related academic journals, conference proceedings and literature reviews. Our results show an increase in the number of recent publications which is an indication of gaining popularity on the part of hybrid expert systems. This increase in the articles is mainly in neuro-fuzzy and rough neural expert systems’ areas. We also observe that many new industrial applications are developed using hybrid expert systems recently.     

Discrete output feedback sliding‐mode control with integral action

This paper presents a novel approach to the problem of discrete time output feedback sliding‐mode control design. The method described applies to uncertain systems (with matched uncertainties) which are not necessarily minimum phase or relative degree one. A new sliding surface is proposed, which is associated with the equivalent control of the output feedback sliding‐mode controller. Design freedom is available to select the sliding surface parameters to produce an appropriate reduced‐order sliding motion. In order for this to be achieved, a static output feedback condition associated with a certain reduced‐order system obtained from the original plant must be solvable. The practicality of the results are demonstrated through the implementation of the controller on a small DC motor test rig. Copyright © 2005 John Wiley & Sons, Ltd.     

广义系统观控性及正则束条件的数值判定

本文提出了一种用于判定广义系统观控性及正则束条件的算法.该算法具有误差小、数 值稳定的特点.     

Observing linear dynamics with polynomial output functions

We address the problem of observing a linear system by a scalar polynomial output function. We show that if the null space of A has dimension at most one, then one can always find such an output function which observes the system and when all the eigenvalues of A are real, then a necessary condition for the observability of the system is that the degree of the polynomial is greater than a certain integer which is related to the maximum number of Jordan blocks corresponding to any eigenvalue.     

Files in an interactive environment

A well designed file system can significantly simplify the design of and increase the reliability of interactive programs. A summary of the specifications of a convenient file system that is substantially independent of the host operating system and some experiences using the system are described.     

HAGI, a High-level Application/Graphics Interface

HAGI is an object-oriented graphics system developed on top of the X window system. In addition to providing facilities that structured graphics systems such as GKS usually have, HAGI supports a high- level graphics paradigm with the following features:

• + In addition to graphical objects, the system provides a class of application objects with a higher level of abstraction than graphical objects.
• + Graphics manipulation operations can be issued simplyfrom application objects without explicitly referring to specific graphical objects. Thus graphics manipulation appears to be transparent to application programmers.
• + Graphical objects are designed to encompass more semantics, thus are at a level close to the application. For example, they useflexible visual objects to determine their visual appearance.

HAGI provides such a high-level application/graphics interface by maintaining a dependency relationship between graphical objects and application objects.     

Integrating job parallelism in real-time scheduling theory

We investigate the global scheduling of sporadic, implicit deadline, real-time task systems on multiprocessor platforms. We provide a task model which integrates job parallelism. We prove that the time-complexity of the feasibility problem of these systems is linear relatively to the number of (sporadic) tasks for a fixed number of processors. We propose a scheduling algorithm theoretically optimal (i.e., preemptions and migrations neglected). Moreover, we provide an exact feasibility utilization bound. Lastly, we propose a technique to limit the number of migrations and preemptions.     

On the necessity of looped-functionals arising in the analysis of pseudo-periodic,sampled-data and hybrid systems

Looped-functionals have been shown to be relevant for the analysis of a wide variety of systems. However, the conditions obtained in previous papers on the analysis of sampled-data, impulsive and switched systems have only been shown to be sufficient for the characterisation of their associated discrete-time stability conditions. We prove here that these conditions are also necessary. This result is derived for a wider class of linear systems, referred to as impulsive pseudo-periodic systems, that encompass periodic, impulsive, sampled-data and switched systems as special cases.     

Towards client-led development of information systems

Abstract. With the incorporation of Information Technology into most areas of modern life, the methods used by the Computer System Analyst (CSA) needs to be reconsidered. To suppose Systems Analysis to be concerned solely with computing is to minimize the task as an information system is greater than a computer system. As such, the information system designer needs to be able to 'appreciate' the wider implications of a clients information needs. An argument is put forward that Information System Design should be undertaken by the client with the CSA acting as facilitator. This paper attempts to provide a re-appraisal of the CSA and arising from this re-appraisal, suggest that ideas originating from organizational analysis could be usefully embodied in the design process for Information Systems.     

An impulsive dynamical systems framework for reset control systems

Impulsive dynamical systems is a well-established area of dynamical systems theory, and it is used in this work to analyse several basic properties of reset control systems: existence and uniqueness of solutions, and continuous dependence on the initial condition (well-posedness). The work scope is about reset control systems with a linear and time-invariant base system, and a zero-crossing resetting law. A necessary and sufficient condition for existence and uniqueness of solutions, based on the well-posedness of reset instants, is developed. As a result, it is shown that reset control systems (with strictly proper plants) do not have Zeno solutions. It is also shown that full reset and partial reset (with a special structure) always produce well-posed reset instants. Moreover, a definition of continuous dependence on the initial condition is developed, and also a sufficient condition for reset control systems to satisfy that property. Finally, this property is used to analyse sensitivity of reset control systems to sensor noise. This work also includes a number of illustrative examples motivating the key concepts and main results.     

Necessary conditions for positive realizability of continuous-time linear systems

This paper deals with the positive realization problem. The problem is to find, from a given transfer function, a state equation in which state variables and the output take nonnegative values whenever initial states and inputs are nonnegative. Necessary conditions are investigated and a new one is given, together with some related results.     

On perturbations of linear controllable infinite-dimensional time-varying discrete-time systems

It is shown that for a broad class of linear (possibly time-varying and infinite-dimensional) discrete-time systems x_k+1 = A_kx_k + B_ku_k the property of being uniformly equicontrollable is preserved under small perturbations of system parameters. The problem of controllability of asymptotically time-invariant systems is also studied.