摘要:

This paper develops an automatic scheme to detect and resolve deadlocks in discrete-event simulation systems with entities capable of requesting multiple units of a resource. The research extends earlier deadlock work on discrete simulation systems with unit resource requests. The purpose of the deadlock handling scheme is to provide for additional capabilities in discrete simulation systems. This is accomplished by endowing the simulation system with appropriate data structures and algorithms. The algorithms presented are based on a graph model of deadlocks in the simulation system. The proposed algorithms identify different categories of permanent and transient deadlocks in the simulation system. A deadlock resolution scheme is also developed in the case of group-processing for permanent deadlocks.

ISSN:0740-817X    

DOI:10.1080/07408179808966451

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper describes the development of a prototype object-oriented software system for discrete event simulation and the embedded decision processes of a system being modeled based on previously defined formalism [1] and the Smalltalk programming language. The paper addresses the modular and structured representations of physical and logical entities of a manufacturing system for simulation modeling in the form of reusable software objects. The software takes advantage of the natural link between object-oriented programming and simulation and utilizes inheritance and other features of object-oriented programming to achieve modular yet uniform representation at every level of the model. After giving a brief overview of the object-oriented modeling environment and the relationships between software objects and formalism constructs, a small number of object classes and their operations are summarized. The intelligent entities of the formalism utilize a knowledge-based non-programmed decision mechanism implemented in Smalltalk.

ISSN:0740-817X    

DOI:10.1080/07408179808966452

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Traditional statistical process control (SPC) techniues of control charting are not applicable in many process industries because data from these facilities are autocorrelated. Therefore the reduction in process variability obtained through the use of SPC techniques has not been realized in process industries. Techniques are needed to serve the same function as SPC control charts, that is to identify process shifts, in correlated parameters. Radial basis function neural networks were developed to identify shifts in process parameter values from papermaking and viscosity data sets available in the literature. Time series residual control charts were also developed for the data sets. Networks were successful at separating data that were shifted 1.5 and 2 standard deviations from nonshifted data for both the papermaking and viscosity parameter values. The network developed on the basis of the papermaking data set was also able to separate shifts of 1 standard deviation from nonshifted data. The SPC control charts were not able to identify the same process shifts. The radial basis function neural networks can be used to identify shifts in process parameters, thus allowing improved process control in manufacturing processes that generate correlated process data.

ISSN:0740-817X    

DOI:10.1080/07408179808966453

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This research presents guidelines to design control processes where improving quality is achieved by improving the manufacturing consistency through the use of intelligent process control. Conventional control processes cannot include the theoretical knowledge, experimental knowledge, and expert knowledge available concerning the product. A hybrid intelligent process control (IPC) combining a continuous simulation (CS) and an artificial neural network (ANN) can make this knowledge available to the operator for process control. This paper presents a methodology for combining the CS and ANN to achieve real-time process control. A human-machine interface (HMI) is included in the process to aid operators in communication with the CS/ANN hybrid IPC. The result of the new process is a real-time process control advisor (RTPCa). A case example for the methodology of formulating, formalizing, validating, and evaluating the RTPCa is given. The case studied concerns galvanizing continuous sheet steel at a steel plant. The CS is written in SIM AN, and the ANN in C. The research validates and evaluates the RTPCa using plant data, simulation output, and face validation by plant personnel. The authors conclude that the benefits of the RTPCa over other forms of IPC include better process communication to the operator, robustness to moderate changes in system parameters, the flexibility to retrain the ANN if conditions change dramatically, and the computation speed necessary for real-time process control. This methodology has further applications to other continuous processes where quality is determined by manufacturing consistency of the product, such as in the pulp paper and film processing industries.

ISSN:0740-817X    

DOI:10.1080/07408179808966454

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

There has been considerable interest in investigating control policies that can be applied to dynamic systems to take advantage of engineering process control (EPC) and statistical process control (SPC). We design two simulation models using SIMULINK to represent control of noisy dynamic systems given by a state-space representation. We use the models on systems with dynamic behavior that have been degraded by an additive ARMA noise process. Our findings show that the combination of EPC and SPC is a more effective policy on a complex dynamic system than on a simple dynamic system.

ISSN:0740-817X    

DOI:10.1080/07408179808966455

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In order to provide models of human behavior useful in selecting tradeoffs in function allocation of inspection systems, an experiment was performed to test five optimization models of the decision component of inspection tasks. Ten subjects examined numbers printed on computer-generated Integrated Circuit (IC) chips to decide whether to accept or reject the ICs under different conditions of defective rate and payoff. The best fitting model was a form of the Expected Utility model, modified to account for the sluggish beta phenomenon. There was a significant relationship between subjects classified as Accurate on the Matching Familiar Figures Test and subjects best fitted by the modified Expected Utility model.

ISSN:0740-817X    

DOI:10.1080/07408179808966456

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Conventional wisdom suggests that a fast single-server queue is preferable to a number of slower single-server queues. The rationale is that if the service rate of the superposed queue is the sum of the service rates of the individual queues, then the average waiting time for the superposed queue is smaller than the weighted average waiting time of the individual queues. This argument, however, assumes that the service time of the customers is perfectly scalable. Unfortunately, this assumption rarely holds in reality. In this paper we analyze the superposition ofM/G/1 queues. We assume that there are scalable and unscalable components in the service time. On the basis of the criteria of average waiting time and average response time, we derive necessary and sufficient conditions for whether the superposition of queues is preferable. Examples of magnetic rotational disks are given to illustrate our findings.

ISSN:0740-817X    

DOI:10.1080/07408179808966457

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Recently Keefer and Verdini (Management Science, 39 (9), 1086-1091 (1993)) and Lau, Lau and Zhang (IIE Transactions, 28, 183–192 (1996)) showed that well-known PERT-type formulas for computing standard deviation from fractiles are very unreliable, and they presented alternative formulas that are more accurate. This note extends their results and present a formula that is simpler, more meaningful and yet more accurate.

ISSN:0740-817X    

DOI:10.1080/07408179808966458

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0740-817X    

DOI:10.1080/07408179808966460

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0740-817X    

DOI:10.1080/07408179808966461

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor