Compact disc standards: an introductory overview

The success of the compact disc (CD) as a storage medium for digital audio has, over the last ten years, resulted in a number of initiatives to use the CD for other applications as well, e.g., as read-only memory for computers, as a storage medium for audio-visual material for multimedia applications, and as a storage medium for photographs. Each of these applications poses additional requirements on how the corresponding information is stored and retrieved, resulting in a range of different CD standards. The functional specifications of these standards are each given a specific color for ease of reference: the Red Book for CD-DA, the Yellow Book for CD-ROM, the Green Book for CD-I, etc. This paper aims at giving an overview of the various CD standards by explaining what is specified in each of the colored books and by indicating how they relate to one another.     

Stability of pull production control methods for systems with significant setups

In manufacturing, a pull production control method is a method of authorizing production based on replenishing current and past consumption, as opposed to forecasts or orders for future consumption. We consider special classes of pull systems for operations that involve significant setup times. In particular, we present a model for variations of the signal Kanban method and the pattern production method, each of which is used in industry when conventional Kanban methods are inappropriate. The paper examines such systems under demands with unpredictable load content but an upper bound on the total load. It is shown that, under appropriate conditions, such systems are stable in the sense that cumulative production at any time trails cumulative demand by no more than a constant. We determine buffer parameters under each protocol (including reorder points in the signal Kanban case) such that the backorder queue will clear to zero and remain empty thereafter. The results are then extended to consider multiple machines fulfilling production authorizations in parallel.     

Optimal control of pull manufacturing systems

We consider the problem of optimal control of pull manufacturing systems. We study a fluid model of a flow shop, with buffer holding costs nondecreasing along the route. The system is subject to a constant exogenous demand, thus incurring additional shortfall/inventory costs. The objective is to determine the optimal control for the production rate at each machine in the system. We exhibit a decomposition of the flow shop into “sections” of contiguous machines, where, in each section, the head machine is the bottleneck for the downstream system. We exhibit the form of an optimal control and show that it is characterized by a set of “deferral times”, one for each head machine. Machines which are upstream of a head machine simply adopt a “just-in-time” production policy. The head machines initially stay idle for a period equal to their deferral time and thereafter produce as fast as possible, until the initial shortfall is eliminated. The optimal values of these deferral times are simply obtained by solving a set of quadratic programming problems. We also exhibit special cases of re-entrant lines, for which the optimal control is similarly computable     

Intelligent tutoring systems: an overview

This is a non-expert overview of Intelligent Tutoring Systems (ITSs), a way in which Artificial Intelligence (AI) techniques are being applied to education. It introduces ITSs and the motivation for them. It looks at its history: its evolution from Computer-Assisted Instruction (CAI). After looking at the structure of a typical ITS, the paper further examines and discusses some other architectures. Several classic ITSs are reviewed, mainly due to their historical significance or because they best demonstrate some of the principles of intelligent tutoring. A reasonably representative list of ITSs is also provided in order to provide a better appreciation of this vibrant field as well as reveal the scope of existing tutors. The paper concludes, perhaps more appropriately, with some of the author's viewpoints on a couple of controversial issues in the intelligent tutoring domain.     

On the search of workstations arrangement in pull production systems

This research presents a model to determine the workstation arrangement and kanban number for pull production systems. Several practical production line characters are considered, and evolutionary algorithms are utilized to obtain the optimal/near-optimal result. The proposed system is a flow-shop, pull production line with N unreliable workstations and N ? 1 inter-stage buffers. Workstations may be allocated to any stage in the production line and have a different processing rate at each stage. Workstations will breakdown/recover at fixed rates, and the operating-breakdown-recovery process is formulated as a Markov process in this model. The size of the inter-stage buffers varies according to the arrangements of workstations. A model is established on the objective of minimizing the total production cost per item of the finished product. The costs considered in the system contain the allocation of workstations, operations, inventory, and production shortage costs. An evolutionary algorithm, genetic algorithm, is used to obtain the allocation of workstations in the production line.     

Main memory database systems: an overview

Main memory database systems (MMDBs) store their data in main physical memory and provide very high-speed access. Conventional database systems are optimized for the particular characteristics of disk storage mechanisms. Memory resident systems, on the other hand, use different optimizations to structure and organize data, as well as to make it reliable. The authors survey the major memory residence optimizations and briefly discuss some of the MMDBs that have been designed or implemented     

Production control of a pull system with production and demanduncertainty

We consider a continuous material-flow manufacturing system with an unreliable production system and a variable demand source which switches randomly between zero and a maximum level. The failure and repair times of the production system and the switching times of the demand source are assumed to be exponentially distributed random variables. The optimal production flow control policy that minimizes the expected average inventory carrying and backlog costs is characterized as a double-hedging policy. The optimal hedging levels are determined analytically by minimizing the closed-form expression of the cost function. We investigate two approximate single hedging policies. It is empirically shown that an approximate policy that uses a single hedging level which is the sum of a production uncertainty term and a demand uncertainty term gives accurate results for the expected average cost     

Testing hybrid control systems with TTCN-3: an overview on continuous TTCN-3

TTCN-3 has gained increasing significance in recent years. It was originally developed to fit the needs of testing software-based applications and systems in the telecommunication industry and has shown its applicability to a wide range of other industrial domains in the mean time. TTCN-3 provides platform-independent, universal and powerful concepts to describe tests, especially for discrete, interactive systems. However, TTCN-3 addresses systems with discrete input and output characteristics only. The lack of powerful means that reasonably allow specifying and evaluating continuous data flow makes TTCN-3 sufficient neither for the automotive industry nor for other industries that deal with highly complex software-based control systems. This paper introduces the notion of streams, stream ports and stream templates to TTCN-3. It revises the initial design of continuous TTCN-3, a TTCN-3 extension for testing continuous or hybrid systems [20,21] and demonstrates the applicability for a case study that is typical for testing embedded control systems in the automotive industry.     

Walsh transform theory and its application to systems analysis and control: an overview

The purpose of this paper is to provide an overview of the works dealing with the application and utilization of Walsh function series and transforms to a variety of systems and control applications. The works reviewed are classified in the following groups: 1. Walsh signal definition and generation, 2. Walsh transform Computation, 3. System analysis using Walsh functions, 4. System identification via Walsh functions, 5. Optimal control via Walsh functions, 6. Block-pulse functions, 7. Miscellaneous properties of Walsh functions, 8. Walsh-to-Fourier transform conversion, and 9. Walsh transform applications.     

基于令牌的无线工业控制网络的信道接入控制

针对无线工业控制网络(WICN)的实时性和可靠性要求,在分析了几种常见的无线局域网的MAC协议(MACA、MA-CAW和IEEE802.11)的不足后,提出了一种基于令牌控制的MAC协议.并且还详细介绍了该协议中的令牌恢复机制、优先级机制和数据帧确认机制,并利用离散事件仿真平台OMNeT 对该协议和CSMA/CA协议进行了仿真对比试验.仿真结果表明,该协议保证了信道接入的公平性,减少了数据传输时延,增强了数据传输的可靠性,适用于无线工业控制网络.     

Type-2 fuzzy sets and systems: an overview

This paper provides an introduction to and an overview of type-2 fuzzy sets (T2 FS) and systems. It does this by answering the following questions: What is a T2 FS and how is it different from a T1 FS? Is there new terminology for a T2 FS? Are there important representations of a T2 FS and, if so, why are they important? How and why are T2 FSs used in a rule-based system? What are the detailed computations for an interval T2 fuzzy logic system (IT2 FLS) and are they easy to understand? Is it possible to have an IT2 FLS without type reduction? How do we wrap this up and where can we go to learn more?     

Digital paint systems: an anecdotal and historical overview

The history of digital paint systems derives from many things-chance meetings, coincidences and boredom, artistic license, brilliant researchers, a wealthy benefactor, and, of course, lawsuits. The author tells the fascinating story-facts first, then anecdotes-in his own words     

Distributed control of production systems

This editorial introduces the special issue of the Elsevier journal, Engineering Application of Artificial Intelligence, on Distributed control of production systems. The current technology in communication and embedded systems allows products and production resources to play a more active role in the production process. This new active capacity will generate major changes in organizations and information systems (e.g., Enterprise Resource Planning (ERP) and Manufacturing Execution Systems (MES)). New approaches are now required for modelling, testing and assessing the features made possible by the decisional and informational capabilities of these new active entities. One among the many possibilities is to use agents and holons, since agent and holon-based approaches assume interaction between intelligent entities to facilitate the emergence of a global behavior. This special issue thus focuses on the possible applications of distributed approaches for the design, evaluation and implementation of new control architectures for production systems. Both fundamental and applied research papers are presented.     

Procedural control in production systems

This paper proposes a general production system architecture that allows procedural control knowledge to be directly represented and used. This architecture, called a controlled production system, is based on a separately specified control structure that effects control over production invocation and interaction independently of the search strategy.It is shown that a controlled production system provides a basis for describing and implementing control constructs which, unlike most existing schemes, is formally adequate and retains all the properties desired of a knowledge based system—modularity, flexibility, extensibility and explanatory capacity. We also show that this architecture provides for a uniform programming methodology—the procedural languages and the declarative languages turn out to be special cases of a controlled production system.Schemes for improving system efficiency and resolving nondeterminism are also examined. It is shown that the separate representation of control provides a basis for a theory of efficiency transformations on production systems, and allows for more effective means of directing search.     

A reactive blended learning proposal for an introductory control engineering course

As it happens in other fields of engineering, blended learning is widely used to teach process control topics. In this paper, the inclusion of a reactive element – a Fuzzy Logic based controller – is proposed for a blended learning approach in an introductory control engineering course. This controller has been designed in order to regulate the workload for each student, according to his activity and performance. The proposed course is based on a web tool called ControlWeb, which includes a complete vision of control topics and is used intensively along the course. The results of the evaluation of the methodology attest its efficiency in terms of learning degree and performance of the students.     

An adaptive pull strategy for remanufacturing systems

Recently, remanufacturing systems have been studied from various viewpoints. Van der Laan and Teunter (Eur J Oper Res 175(2):1084–1102, 2006), for example, proposed simple heuristics for push and pull remanufacturing strategies. However, because they are only simple heuristics they are not very useful in a stochastic demand situation. An adaptive strategy should be incorporated into the pull strategy to improve performance; therefore, we propose an adaptive pull strategy for remanufacturing systems that can control manufacturing and remanufacturing rates in the remanufacturing system. The performance and effectiveness of our proposed system is analyzed by Markov analysis, and the results are shown in this paper.     

Decentralized control: An overview

The paper reviews the past and present results in the area of decentralized control of large-scale complex systems. An emphasis is laid on decentralization, decomposition, and robustness. These methodologies serve as effective tools to overcome specific difficulties arising in large-scale complex systems such as high dimensionality, information structure constraints, uncertainty, and delays. Several prospective topics for future research are introduced in this contents. The overview is focused on recent decomposition approaches in interconnected dynamic systems due to their potential in providing the extension of decentralized control into networked control systems.     

Parallel models of computation: an introductory survey

The paper gives an overview of some models of computation which have proved successful in laying a foundation for a general theory of parallel computation. We present three models of parallel computation, namelyboolean andarithmetic circuit families, andParallel Random Access Machines. They represent different viewpoints on parallel computing: boolean circuit families are useful for in-depth theoretical studies on the power and limitations of parallel computers; Parallel Random Access Machines are the most general vehicles for designing highly parallel algorithms; arithmetic circuit families are an important tool for undertaking studies related to one of the most active areas in parallel computing, i.e. parallel algebraic complexity.     

工业控制系统IDS技术研究综述

工业控制系统(Industrial Control System,ICS)作为工业大脑,与互联网连接的趋势越来越明显,但是开放的同时也暴露出严重的脆弱性问题。入侵检测作为重要的安全防御措施,能及时发现可能或潜在的入侵行为。论文从ICS网络安全现状及国家法律政策入手,首先介绍了ICS系统架构及其特点,给出了IDS入侵检测系统(Intrusion Detection System,IDS)的介绍,其次从误用入侵检测、异常入侵检测两个方面,对现有的ICS IDS的技术、算法的研究现状进行分析,最后针对当前ICS IDS的发展与应用现状,对整个ICS IDS的研究趋势进行了展望。     

Time-delay systems: an overview of some recent advances and open problems

After presenting some motivations for the study of time-delay system, this paper recalls modifications (models, stability, structure) arising from the presence of the delay phenomenon. A brief overview of some control approaches is then provided, the sliding mode and time-delay controls in particular. Lastly, some open problems are discussed: the constructive use of the delayed inputs, the digital implementation of distributed delays, the control via the delay, and the handling of information related to the delay value.