Showing papers in "Simulation in 1986"
TL;DR: It is concluded that the most fruitful areas of cross-fertilization are advice-giving ex pert systems that assist the simulation scientist and simulation user, new simulation tools built from knowledge-based tools, and intelligent front ends for simulation packages.
Abstract: Simulation and expert systems are remarkably similar. Both employ various representations to model some aspect of an uncertain world, with the model being formed as a piece of com puter software. This is then employed to aid decision making. Ideas about combining simulation and expert systems are presented, and a taxonomy is developed. It is concluded that the most fruitful areas of cross-fertilization are advice-giving ex pert systems that assist the simulation scientist and simulation user, new simulation tools built from knowledge-based tools, and intelligent front ends for simulation packages. Advice-giving systems will increasingly be part of simulation environments, rather than stand alone. They will be aimed primarily at the in experienced simulationist. An example of a system developed in this vein, which advises on experimentation with transaction flow models, is presented. Regarding the use of knowledge-based tools, induction as an aid to the development of a discrete model is considered.
204 citations
TL;DR: Journal and conference Proceedings' articles spanning many years have been reviewed, including the development of algorithms for each of the three strategies, and the use of the algorithms for in-depth comparisons of the char acteristics of languages employing each strategy.
Abstract: In regard to available features, discrete-event simulation languages differ in many respects. There is, however, one aspect of a simula tion language that transcends all others in significance - na...
55 citations
TL;DR: A vapour compression heat pump simulation model has been developed to predict the overall performance of a system by employing a simple model for the components of the heat pump cycle - namely, the compressor, condenser and evaporator.
Abstract: A vapour compression heat pump simulation model has been developed to predict the overall performance of a system by employing a simple model for the components of the heat pump cycle - namely, the...
30 citations
TL;DR: The incorporation of two AIP techniques in modelling and simulation of knowledge-based simulation and Al supported model synthesis are illustrated on the basis of research activities in the Benelux countries.
Abstract: Advanced Information Processing (AIP) techniques are felt to play an important role in next generation simulation tools. Here we will review and illustrate the incorporation of two such AIP techniques in modelling and simulation. Simulation-oriented information-base management systems are considered to auto matize one of the major activities, peripheral to large-scale modelling and model implementation : the management of the descriptive and quantitative data involved. On the other hand, attention is paid to the impact of artificial intelligence techniques in modelling and simulation. Knowledge-based simulation, Al supported model synthesis and some additional topics with respect to integrating Al and the system analysis approach are briefly reviewed.Some concepts are illustrated on the basis of research activities in the Benelux countries.
29 citations
TL;DR: This work proposes a description system based on the concept of hierar chical decomposition utilizing the Ada programming language in conjunction with established diagrammatical decomposition methods, and shows how a simulation of the operation of the manufacturing cell can be embedded in its description.
Abstract: A useful tool in the development of flexible automation is a system description language which can generate a complete func tional description of a manufacturing cell of arbitrary complexity. We propose a description system based on the concept of hierar chical decomposition utilizing the Ada programming language in conjunction with established diagrammatical decomposition methods. The distinguishing aspect of our work is that it takes advantage of certain features of Ada (such as type checking) to create a description that can be automatically verified for con sistency Simulation is often an indispensable tool in the develop ment of manufacturing systems. We show how a simulation of the operation of the manufacturing cell can be embedded in its description. Finally, we apply the methodology to a specific instance of a manufacturing cell.
22 citations
TL;DR: A system for simulating neural networks has been written in the LISP dialect, Scheme, using an object-oriented style of program ming, rather than the standard numerical techniques used in previous studies, which allows the construction of hierarchical networks with several interacting levels.
Abstract: A system for simulating neural networks has been written in the LISP dialect, Scheme, using an object-oriented style of program ming, rather than the standard numerical techniques used in previous studies. Each node in the Scheme network represents either a neuron or a functional group of neurons, and can pass messages which trigger computations and actions in other nodes.The Scheme modeling approach overcomes two major problems inherent to the standard numerical approach. First, it provides a flexible environment for systematically studying the effects of perturbing a network's structure, response, or updating param eters. In fact, the Scheme system can recreate any previously studied neural network. Second, it allows the construction of hierarchical networks with several interacting levels. This system can handle hierarchical organization in a natural way, because a single node in a Scheme network can contain a model of an entire lower level of neural processing. The implementation of neural networks wi...
10 citations
9 citations
TL;DR: The Function Net approach, which has been derived from the Petri Net model, provides general but compact modeling capabilities combined with a clear graphic notation, and has been successfully applied in a performance evaluation model of database machines.
Abstract: Simulation models often suffer from a discrepancy between general modeling capabilities and support for efficient ex periments in a particular application field. The Function Net approach represents a tool to bridge this gap. The model, which has been derived from the Petri Net model, provides general but compact modeling capabilities combined with a clear graphic notation. Integrated with the model is a software package to conduct simulation experiments. A number of useful features like predefined elements for statistical analysis are already available in the system. The tool has been successfully applied in a performance evaluation model of database machines. An analysis of a sample architecture is used to illustrate the capabilities of the Function Net approach.
7 citations
TL;DR: A model to aid in the evaluation of disk subsystem performance, with special emphasis on the rotational position sensing (RPS) feature due to its widespread use, which produces I/O service times broken down by device within the disk subsystem.
Abstract: The performance of a computer system is often directly depen dent on the performance of the disk subsystems supporting it. Therefore, we have developed a model to aid in the evaluation of disk subs...
3 citations
TL;DR: Since its inception in the late nineteen forties simulation has undergone some interesting evolutionary changes.
Abstract: The use of computers to model things, both real and imaginary, and the use of those models as surrogates for investigative and experimental purposes, constitute the art and science of simulation.Since its inception in the late nineteen forties simulation has undergone some interesting evolutionary changes. Paced by the development of rapidly improving computing and allied equip ment, the technology and methodology of simulation have faced — and to varying degrees learned to cope with - changing chal lenges as the ever-widening fields of application have multiplied.Hard limits are not in sight. However, vestiges of some original problems remain while others have been solved as simulation progresses from an art toward becoming a science.
3 citations
TL;DR: An interactive threaded command language (TCL) was developed for design and simulation applications that incorporates the extensibility and interactive features of threaded interpretive languages, but it allows use of all the flexible data structures and numerical capabilities of FORTRAN 77.
Abstract: An interactive threaded command language (TCL) was developed for design and simulation applications. The FORTRAN imple mentation of this language emphasizes a basic approach toward developing simulation software rather then the specific command language. TCL incorporates the extensibility and interactive features of threaded interpretive languages such as FORTH and STOIC, but it allows use of all the flexible data structures and numerical capabilities of FORTRAN 77. The approach presented here can easily be adapted to develop other higher level languages tailored to specific applications.Another interesting feature, within a FORTRAN 77 program, is the handling of various display terminals through an internal data structure and an ASCII text file that contains the terminal's "characteristics".
TL;DR: This current article focuses on the evaluation of six expert system shells that are currently available for in dustrial applications.
Abstract: "Applications of artificial intelligence" was featured on page 306 in the June 1985 SIMULATION. A section titled, "Expert systems for industrial applications, by Warren Foster, looked at the basic perspective of artificial intelligence (Al) and how it is used in solving industrial problems. This current article focuses on the evaluation of six expert system shells that are currently available for in dustrial applications.
TL;DR: In this paper, the Adams-Moulton numerical integration technique was used to solve the coupled differential equations of a coal gasifier and the trajectories of variable changes were plotted in phase planes.
Abstract: Dynamic simulation and phase plane analysis techniques were used to examine the stability of an entrained coal gasifier. The mathematical model consists of a set of algebraic and ordinary differential equations which represent the time-dependent in terrelationships among reaction kinetics, heat transfers and mass transports; and the variable physical properties of both gaseous mixture and coal particles. For simplicity, the shift-reaction and volatilization were not considered in the study. This model is expected to be valid for dynamic simulation of gasification of char with low iron content and negligible shift reaction.During simulation the coupled differential equations are solved by the Adams-Moulton numerical integration technique.After the simulation is run to a steady state, the temperatures and composition of this system were perturbed in many com binations. The trajectories of variable changes were plotted in phase planes. It was noted that the system was stable for all the variable combinations...
TL;DR: Experiments with a simulation model where the above assumptions have been relaxed indicate that the results are significantly affected by these assumptions and that the steady state may take too long to reach.
Abstract: Locational issues arise in the provision of urban services; for in stance, finding an optimal home location for a service facility in an urban setting is difficult when the interarrival times of se...
TL;DR: In this article, the authors used SIMAN to simulate a preheat train with different over-design factors and found that the operating cost was minimized by maximising the furnace coil outlet temperature.
Abstract: Determining the sizes of heat exchangers which minimize the cost of a crude preheat train were investigated. SIMAN was used to simulate the system for different overdesign factors, and it was found out that the operating cost was minimized by maximiz ing the furnace coil outlet temperature.An overdesign factor of 10% yielded the best results; this is less than the 25% normally used in practice. This suggests that time- dependent simulation can lead to tighter control of overdesign in the design of process equipment under risk and uncertainty conditions. Time-dependent simulations are rarely used in the chemical process industry.
TL;DR: In this paper, rank transformations of simulated multivariate data with a com-mon mean vector are shown to be functions of correlation struc ture only, and are used in certain multivariate analyses such as in the Multivariate Multisample Rank Sum and Median tests.
Abstract: Transformations of multivariate data to ranks for each multivariate response is used in certain multivariate analyses such as in the Multivariate Multisample Rank Sum and Median tests.Rank transformations of simulated multivariate data with a com mon mean vector are shown to be functions of correlation struc ture only.
TL;DR: The researchers are exploring ways to increase the productivity of the people who program the real-time computers by developing software written in Ada, the object-oriented language recently adopted as a standard for military computers.
Abstract: The R&D Center is comprised of four component Laboratories: Chemical, Electronics, Engineering Physics, and Materials. In these four components are a diversity of talent creating a unique strength the ability to assemble large, multidisciplinary research terms to tackle complex projects. The Engineering Physics Laboratory is developing and integrating the technologies that will launch a generation based on &dquo;intelligent&dquo; machines. The researchers are exploring ways to increase the productivity of the people who program the real-time computers. This includes an effort aimed at workstations specifically tailored for developing software written in Ada, the object-oriented language recently adopted as a standard for military computers.
TL;DR: The preliminary modelling of simulation steps required in the development of a generalised CAD (Computer-Aided-Design) package for textile machinery designers is presented and the false twist texturing process is chosen as the starting point.
Abstract: The preliminary modelling of simulation steps required in the development of a generalised CAD (Computer-Aided-Design) package for textile machinery designers is presented.The false twist texturing process (FTTP) is chosen as the starting point, since it is the most important texturing process and it con tains most of the thermomechanical processes used in other tex turing processes. It also has an inherent problem associated with it; at high speed it is very difficult to analyse using conventional analytical techniques.The paper is divided into four sections: an introductory section which describes the false twist texturing process and reviews what modelling work has been done to date; this is followed by a sec tion which describes the simulation techniques employed and the mathematical models used; a results section where the simulation techniques are validated; and a conclusions section.
TL;DR: A relatively small and inexpensive peripheral array processor is described to be used to identify and characterize sources of water pollution on the basis of measure ments of pollution concentrations downstream from suspected sources and its performance is evaluated.
Abstract: In the modeling of distributed parameter systems, it is sometimes necessary to utilize system observations to identify or estimate the boundary conditions of the field. For example, in dealing with water resources systems, it may be desired to identify and characterize sources of water pollution on the basis of measurements of pollution concentrations downstream from suspected sources. A computational technique based on pattern recognition has been found to be relatively effective in this application. However, the algorithms involved are highly computation-intensive and therefore tend to place a considerable burden on most conventional digital computer facilities. Array processors, though primarily designed for signal processing are playing an increasingly important role in the modeling and simulation of physical systems. It is a purpose of this paper to describe the application of a relatively small and inexpensive peripheral array processor to this problem and to evaluate its performance.
TL;DR: Speakers from the University of Central Florida (UCF) presented three facets of simulation education, including the Masters Program in Simulation Systems at UCF, which was developed in response to booming industrial and defense simulation opportunities in the Orlando area.
Abstract: Continuing the discussion of &dquo;Simulation in Education,&dquo; session chairman, Fred Simons (Florida State University), introduced speakers from the University of Central Florida (UCF) who presented three facets of simulation education. Lucy Morse covered &dquo;The future of workstations in engineering education&dquo;; Harold Klee discussed &dquo;The use of simulation in teaching systems analysis&dquo;; and, a presentation prepared by Jose A. Sepulveda and Christian S. Bauer covered &dquo;The Masters Program in Simulation Systems at UCF&dquo; The latter program was developed in response to booming industrial and defense simulation opportunities in the Orlando area.
TL;DR: A range-doppler spread target model is modified to obtain a clutter modeling model that is applied in a simulation of an FMCW radar sensor that uses an adaptive moving target indicator and a monopulse antenna to detect slow-moving ground targets.
Abstract: A range-doppler spread target model is modified to obtain a clut ter model by including the effect of beam and range gate shape. This clutter modeling is then applied in a simulation of an FMCW radar sensor that uses an adaptive moving target indicator (AMTI) and a monopulse antenna to detect slow-moving ground targets. The ability of the AMTI to discriminate a slow-moving point target from ground clutter is shown via simulation.