bluuebunny/crossref_metadata_2025 huggingface dataset:
Unpredictable/Unsimulatable?
Authors: Bekey George A.
Published: March 2008

George Bekey has been involved in simulation since 1950, when he started graduate work at UCLA (BSEE, UC Berkeley, 1950) and worked as a research assistant on the UCLA mechanical differential analyzer and ac network analyzer. He was in charge of those two machines from 1952-54, when he was inducted into the U.S. Army and spent two years "simulating an enlisted man. After discharge he did analog computer simula tions with Beckman Instruments in Richmond, Califor nia, and subsequently organized and directed a Beckman analog simulation center in Los Angeles.

In 1958 George joined TRW (Thompson Romo Woolridge, the Space Technology Laboratories) and was named head of its Analysis and Simulation Center, where he was responsible for hybrid computers. After receiving his PhD from UCLA in 1962, he spent another year at TRW simulating manned space vehicles before joining the USC faculty, where he has been since 1963. For the last eight or ten years he has continued his simulation activities, but now with digital computers and digital simulation languages. He is primarily interested in mathematical models of biological sys tems, manual and automatic control, and system iden tification-as well as backpacking in the High Sierras.
The Greatest Challenge
Authors: Forrester Jay W.
Published: March 2008

Jay W. Forrester began his simulation work when he was directing development of the Whirlwind computer for the study of engineering systems at MIT, circa 1950, and the SAGE man/machine air-defense system at MIT's Lincoln Laboratories. Later, as professor of management at MIT, he developed system dynamics, a methodology which makes use of computer modeling and simulation to study corporate and social systems.
Hear it from the UK
Authors: Crosbie Roy E.
Published: March 2008

Roy Crosbie first became involved with simulation in 1957 when, as a senior at the University of Liverpool in England, he designed "a 4-amplifier, 8-tube super computer. " In spite of that, he says, he was awarded his BEng degree and went on to use "bigger and better analog computers" in his PhD research on nuclear reactors. After a stint with Marconi, Roy returned to academia in 1963, this time with the Royal College of Advanced Technology - now the University of Salford. We in simulation, and especially in SCS., are indebted to Roy for his work in putting together the United Kingdom Simulation Council in 1968 and for continuing to contribute his valuable talents ever since. Besides being a founding member of the UKSC, Roy has served since its inception as -either secretary or chairman. He has also been a frequent contributor to Simulation.
Three Short Thoughts - With Long Implications
Authors: Utsumi Takeshi
Published: March 2008

Tak Utsumi is a fireball. Ask a question and you get an answer-probably many pages in length. If I had asked for details I would probably have gotten a book! I will here try to condense his six-page reply. (However, all of it would be of interest if we only had room.)

Heat-transfer phenomena with chemical reactions got Tak involved with simulation in 1960 when he was a PhD candidate at the Polytechnic Institute of Brook lyn. Since then he has been with Mobile Chemical

Company, MIT Sloan School of Management, Stone and Webster Engineering Corporation, Mitsubishi Research Institute (in Japan), and Japan GLOSAS (GLObal Systems Analysis and Simulation) Association before forming his own company GIS/USA.

It is interesting that in 1971 Tak began advocating the term "peace game" instead of "war game." It was that way of thinking that led to the formation of GLOSAS, rahich is dedicated to the use of computer conferencing and distributed computer simulations simultaneously running different area and sector models to solve the problems associated with complex socioeconomic systems.

Currently., this simulation activist is concerned with the commercial application of the GLOSAS concept - the promotion of worldwide understanding and coop eration among people of various countries through technology and information transfer.
Models and reality : some reflections on the art and science of simulation
Authors: Bekey George A.
Published: March 2008

This paper presents a philosophical overview of simulation, with an emphasis on the nature of the relation between models and the systems they repre sent. Model-making is shown to be an essential feature of human thinking. The "abstraction ladder," which leads from observations of reality to mathemat ical models, is reviewed from a semantic viewpoint. The problem of validation of the results of a simula tion is then outlined. The paper concludes with some philosophical observations on the relation of model and reality.
WISPAC: a parallel array computer for large-scale system simulation
Authors: Cyre W.R. , Davis C.J. , Frank A.A. , Jedynak L. , Redmond M.J. , Rideout V.C.
Published: March 2008

This paper discusses the multiple-instruction stream/ multiple-data stream (MIMD) Wisconsin parallel array computer (WISPAC). The design of the computer makes use of current, low-cost microprocessor technology and is intended to meet future needs in large-scale simulation. A modular approach is taken where smaller configurations are meant as direct competi tive replacements of current hybrid systems. Larger configurations will allow high-speed solution of large-scale simulation problems using a one-to-one correspondence of each microprocessor to each node of the system being modeled. A three-dimensional configuration is used to allow a high degree of iso morphism between the computer setup and the model to be investigated. These schemes simplify programming requirements and overall machine conceptualization. New techniques of high-speed internode communication utilizing a serial "pass-through" scheme are des cribed. The scheme allows general cross-array com munication that is competitive with cross-point methods. Initial work on a minimal parallel config uration is also described.
Right turn on red- a traffic management simulation
Authors: Lidor Gideon , Wiener Richard
Published: March 2008

This paper outlines a stochastic model of the right- turn-on-red (RTOR) policy for a high-density urban area consisting of one-way streets. This model is used to investigate the effects of (1) cross-street traffic volume, (2) right-turn lane traffic volume, (3) pedestrian arrival rate, and (4) balking rate for right-turning vehicles. The model provides the methodology for studying the RTOR maneuver under various conditions. Specific recommendations on when to use RTOR are developed for typical urban conditions.
Models for the automatic factory
Authors: Talavage Joseph J.
Published: March 2008

The structure of computerized manufacturing systems is quite complex and only a few systems have been implemented. A design procedure for such systems is sketched, and simulation is seen to be useful for evaluating alternative configurations. An existing system at Caterpillar Tractor is described and a simulation model is shown for the system. An example is shown of the model's application to improve the productivity of the Caterpillar system.
Issues in the development of a model for planning health manpower
Authors: Standridge Charles R. , Alan A. , Pritsker B. , Delcher Harry
Published: March 2008

This paper describes the development of a GASP IV simulation of the primary health-care system of Indiana. In the course of this research, other prob lems were found to be as important as the construc tion of the model. These problems included data acquisition and analysis, definition of system per formance measures, the comparison of alternative policies, and the interaction between physicians and system analysts.
Large-scale simulation of brain cortices
Authors: Wittie Larry D.
Published: March 2008

BOSS is a highly parameterized large-scale discrete- event simulation system for brain structures. BOSS has been written in FORTRAN for the Univac 1106 and in PASCAL for the Control Data Cyber 173. It permits the simulation of detailed three-dimensional models involving up to 8,000 neurons and 80,000 synapses. Instead of describing the individual elements of a model, parameters specify spatial lattices and intersecting probability distributions which position neurons and synapses with any desired variance. To avoid sorting overhead, time is finely quantized and events are posted and scanned via a circular array of pointers to lists of simultaneous events. Synap tic weights may be modified systematically to reflect changes resulting from learning. BOSS can be used to simulate large logic arrays as well as neural networks.
Simulation of conveyor systems with dual inputs
Authors: Elsayed E.A. , Elayat Hatem , Ragab A.M.
Published: March 2008

This paper develops a simulation approach to the solution of closed-loop conveyor systems for which analytical solutions are infeasible or too compli cated. In addition, the paper considers cases involving more than one type of input to the conveyor systems. The arrival distribution patterns of re circulated units are also studied. The systems' measures of performance are evaluated. GPSS III/360 is utilized as the simulation language.
Operation of multivariable function generators
Authors: Asthana Abhaya
Published: March 2008

The multivariable function generator (MVFG) is a multiport device which, given a set of continuous bounded analog inputs at time t, produces estimates for a set of bounded outputs after a processing time delay Δt u. The transfer characteristics of the MVFG can be both arbitrary and nonlinear and are specified by defining the output variables at a finite number of coordinate points. The operation of the device described in this paper is based on first-order interpolation techniques and combines the flexibility of digital processing with the continuity and speed of analog processing. The speed and accuracy of the device result from its distributed-processor archi tecture in which several independent operations proceed concurrently. Sources of errors and tech niques for minimizing their effects are discussed.
Large network models using the brain organization simulation system (BOSS)
Authors: Wittie Larry D.
Published: March 2008

BOSS is a discrete-event simulation system designed for large models of neural networks. Because of the flexibility of its parameters, it has also been used to simulate an integrated-circuit logic array intend ed for picture processing. A test of a circuit of 2700 logic elements illustrates the pictorial inputs and outputs for BOSS simulations. A much more com plex model of a section of cerebellar cortex involving 22,000 synapses and 1,800 neurons of 12 different functional types has been used to demonstrate one possible mechanism by which the brain is able to learn.
Micronet: A reconfigurable microcomputer network for distributed systems research
Authors: Wittie Larry D.
Published: March 2008

MICRONET is a reconfigurable network of closely cou pled microcomputers intended for general-purpose com puting. The initial system will consist of 16 Digital Equipment Corporation LSI-11 microcomputer nodes, each with its own set of peripherals. The nodes are linked via front-end computers which send packet-switched messages over shared buses which form a passive com munications network.

The specially designed front ends are on interface cards which fit in LSI-11 backplanes in each node. Each front end controls three high-speed ports: two for communications on shared buses at 0.7 megabytes per second and one for direct memory access at 0.3 megabytes per second to the LSI-11. Each front end contains 4096 bytes of memory for use in queuing message packets. Each uses two microprocessors: a Signetics 8X3006 for logic control and a Zilog Z-808 for communications routines.

MICRONET has been designed to be a flexible research and simulation tool for studying distributed computer hardware and software. The topology of its communi cations network can be altered simply by reconnecting cables to a bus-definition board. Software for MICRONET will include a distributed operating system, parallel programming languages, and a network version of a simulation system for modeling the brain.
A modeling package for simulation of computer networks
Authors: Schneider G. Michael
Published: March 2008

The VANS (Value Added Network Simulator) system re presents a new approach to the simulation of distrib uted resource-sharing computer networks. It allows the network designer either to manipulate the struc ture of the protocols (sets of rules) that govern the handling of communications in different types of networks or to investigate the effects of changing the parameters of networks operating under a fixed set of protocols. This paper describes the VANS sys tem and its use in conducting a wide range of experi ments in network design. While a number of simula tion programs permit experimenting with network parameters, VANS is the first to permit both that type of experimentation and experimentation with the protocols that control the operation of a computer network.
Simulation of random packing of spheres
Authors: Jodrey W. Steven , Tory Elmer M.
Published: March 2008

PACKS simulates the very slow settling of rigid spheres (as in sedimentation) from a dilute suspen sion into a randomly packed bed. Spheres are intro duced one at a time in a potential field and fall or roll until they occupy one of the available sites. The position of an incoming sphere is calculated at each of the significant events in its history. Thus, probabilities for each site are assigned on a realis tic basis. Periodic boundary conditions eliminate wall effects (smooth walls induce partial ordering) and a rough floor reduces the disturbance at the bottom. These features make a greater proportion of simulated spheres truly random in final position and so available for analysis. A new search routine greatly reduces the time required to assemble a pack ing. Preservation of the addresses of supporting spheres simplifies the subsequent analysis for near est neighbors. Packings of 100 000 or more spheres are feasible. The simulation has potential applica tions in crystallography, soil engineering, biology, nuclear engineering, and petroleum engineering.
Concepts for advanced simulation methodologies
Authors: Ören Tuncer I. , Zeigler Bernard P.
Published: March 2008

Conventional simulation techniques have three short comings when applied to large-scale modelling : They provide an inadequate man-machine interface, they provide a poor conceptual framework, and they lack needed tools for managing data and model. These shortcomings may be ameliorated by developing new simulation languages that differentiate the function aZ elements of simulation programs and by recognizing the goals of these functional elements. This paper provides concepts for the design and implementation of such advanced simulation methodologies.
The Ten Most Frequent Causes of Simulation Analysis Failure- and How To Avoid Them !
Authors: Annino Joseph S. , Russell Edward C.
Published: March 2008

Simulation analysis studies too often fail to yield use ful results, and the reasons for failure are frequently the same. This paper states the ten most common causes of failure and outlines the principles for overcoming them.
Methodological problems in global models
Authors: Gelovani V.A. , Dubovsky S.V. , Yurchenko V.V.
Published: March 2008

This paper discusses the combined use of extrapola tive and normative models for studying global socio- economic problems. The prescribed modeling approach is illustrated through use of WORLD3, presented originally by D. L. Meadaws et al. in The Dynamics of Growth in a Finite World. Included is a compari son of Meadows' standard simulation run with a sub stantially improved modification that resulted from use of the authors' normative approach.
Controller for a solar heating system with an electrical backup
Authors: Eltimsahy Adel H. , Santos Emilio A.
Published: March 2008

This paper describes the mathematical modeling and optimization of a solar heating system that stores reserve energy from the electric power network. The paper focuses on the design of a controller which minimizes use of electric energy, uses that energy at times when its cost is low, and maximizes human comfort.

The mathematical model has identifiable state vari ables, control input variables, disturbance input variables, and system parameters. The state vari ables are temperatures in the solar collector, in the first storage tank, in the second storage tank, and in the room and walls. Electric power input to the heating coils, heat pump, and circulating pump form the control input vector. Ambient temperatures and solar radiation are treated as uncontrollable input variables.

The objectives of the optimization scheme are

(1) maximizing the use of solar energy, (2) minimi zing the cost of electricity, and (3) maximizing human comfort. These are combined into an overall system performance index. A suboptimal feedback con troller based on this index uses an extension of Pearson's method 6; it involves (1) linearizing the system about an equilibrium point which shifts with time, (2) employing on-line computer control of the linearized system, and (3) changing the control strategy frequently.

Results of computer simulations show that the formu lated controller acceptably achieved the design objectives.
The treatment of inputs in real-time digital simulation
Authors: Bernstein Dennis S.
Published: March 2008

Real-time simulation often requires a computer to interact with external hardware in a dynamic loop. Data must be sampled from input signals and incor porated into the numerical integration algorithm to evaluate the derivatives of the state variables. Also, data from the integration must be available for external use with a minimum of delay. This paper will show that, because of these requirements, cer tain numerical integration routines are best suited for real-time simulation. A new fourth-order Runge- Kutta routine designed for real-time use is presented along with its derivation.
The dynamics of water policy in southwestern Saudi Arabia
Authors: Picardi Anthony C. , Saeed Khalid
Published: March 2008

The effects of water-supply policies on growth in southwestern Saudi Arabia are examined with the aid of a system dynamics model. The Southwest Zone is predominantly agricultural and relatively isolated by its difficult terrain. It is losing population to regions of the country in which industry, commerce, and the public sector are growing more rapidly.
A model of the warp dynamics on power looms
Authors: Bedini Raffaele , Del Taglia Andrea
Published: March 2008

In some types of power looms, the tension on the warp (lengthwise strands of yarn) is regulated by matching the rate at which yarn is unwound from the beam (yarn supply roll) to the weaving rate. This paper reports a simulation study of one such type of loom in which the regulator permitted too much variation in tension and under certain conditions became unstable.

The study uses a nonlinear model of the warp dynamics derived from fundamental principles of elasticity theory and rigid-body equilibrium. The mathematical model is ill-suited to the application of the general methods of control theory. A simulation approach was therefore chosen; it uses a Continuous System Modeling Program (CSMP) operating on a PDP 11/40 computer. The model was successfully calibrated using experimental data from the shop and was validated by comparing its output with manufacturer's data.

An extensive study of the warp dynamics under various operating conditions was completed with only two man- months of work. Knowledge gained in the study led to a simple, retrofittable modification of the loom. Its purpose was to improve the control of warp tension and to eliminate the instabilities. It was analyzed by simulation, built in the shop, installed, and found to work well. It is now incorporated in the manufac turer's standard machines.
Faculty dynamics
Authors: Innis George S.
Published: March 2008

University faculty members may be characterized by a set of interacting attributes. Some of these are con crete (e.g., rank, tenure, years of service) and others abstract (e.g., quality, production). This paper presents a model embodying specific but modifi able rules describing the interactions. The model is then used to investigate the consequences of adminis trative practices in hiring, promotion, tenure, and retirement.

While the abstract attributes are measurable, no attempt to measure them was made; instead, reasonable assumptions (obtained by consensus) about them and their interactions were made. The results of the simulation runs, of course, depend on these assump tions, but they suggest that promotion and retirement are much less important than hiring policies.
Making better use of jurors through computer simulation
Authors: Greilich William
Published: March 2008

The examination of social systems requires the devel opment of flexible tools. This paper focuses on the court system, specifically on one of its most import ant areas, the effective operation of the jury system. The paper examines the management of juries and pre sents a simulation which can aid in developing new policies for using jurors more efficiently.
Signal flow graphs for network simulation
Authors: Tavangarian Djamshid , Waldschmidt Klaus
Published: March 2008

This paper describes an interactive graphical use of signal flow graphs (Mason graphs) to simulate linear networks in either the time or frequency domain. The program allows the user to describe, manipulate, and compute signal flow graphs for up to 64 nodes on a screen. Since many readers may not be familiar with these graphs, the paper includes a general introduction to them.

The program is written in FORTRAN IV and runs on a Hewlett-Packard 21 MX minicomputer. A low-cost, low- resolution (256x 256 points) TV display is used as the input and output device.
A comparison of SIMULA and GPSS for simulating sparse traffic
Authors: Atkins M. Stella
Published: March 2008

This paper describes the features needed in a simula tion language to model a network with sparse traffic. GPSS does not provide two necessary features, inter process communication and list processing, in con venient forms. SIMULA's built-in list-handling features and its powerful class construct can be used to model such a traffic network conveniently. The differences between the languages are illustrated by modelling a road network in two versions of GPSS and one of SIMULA.
Dynamic analysis of a simplified free-piston Stirling engine
Authors: Daniele Carl J. , Lorenzo Carl F.
Published: March 2008

Lumped-volume dynamic equations are derived using an energy-state formulation. This technique requires the writing of state functions for kinetic and poten tial energy. A Rayleigh dissipation function accounts for losses in the system. Using these functions, a Lagrangian is formed and the equations of motion for the system are derived. An example of the application of this technique is a model of the free-piston Stirling engine. The model was simplified and pro grammed on an analog computer. Data obtained by simulation compares favorably with experimental data.
Simulation and the space shuttle
Authors: Pratt Charles A.
Published: March 2008

One of the current projects in which simulation plays a critical role is the United States space shuttle program. Clearly, simulation is the only way to investigate the feasibility and safety of the multi- billion-dollar space craft program. Its launch, orbit, and re-entry have been analyzed meticulously by an experienced team of engineers, but we still cannot be certain that the craft works properly until after the first landing from space.

That first landing is critical. The spacecraft has one shot at one of three 2.8-mile-long landing strips that NASA (The U.S. National Aeronautics and Space Administration) has constructed in widely scattered locations: the Kennedy Space Center in Florida, Edwards Air Force Base in California, and White Sands Missile Range in New Mexico. Its two highly trained pilots know they have one shot at that runway, and one shot only. While simulation has been used in every aspect of the program, its use in training the pilots is certainly one of the most important aspects of the entire effort. Let's talk to the man in charge of Mission Simulation and Training at the Johnson Space Center in Houston, Texas. He is Frank Hughes, a 15-year veteran of simulation at NASA.
Designing a production line for howitzer projectiles
Authors: Sims Michael K.
Published: March 2008

As real budgets have become increasingly austere, the Department of Defense has recently begun to rely on simulation as a planning tool. In some cases simulation has become mandatory before significant projects are undertaken. This was the case in the modernization of a production line for howitzer pro jectiles in the Midwest. Simulation proved worth while in this project. Although there was initial resistance to the burdensome data-collection effort, simulation gained increased credibility with the con tracted engineering design team. It provided great insights into the requirements of this queuing net work during the initial phases of the design. Later, after initial development and verification, the model was used to explore a variety of design contingencies.
Simulation of a telecommunications multiprocessor switching system
Authors: McQuade Eamonn , Salih Abdul M. , Gray Harry J.
Published: March 2008

The stringent real-time operating requirements of telecommunications switching systems have prompted the design of special-purpose processors that allow modular growth and provide high levels of reliabil ity, availability, security, flexibility, and capacity. One such system is the Mark II BL (MKIIBL), a telecommunications-oriented multiproces sor developed by GEC as the controller for the British Post Office's SYSTEM X. The complexity of the Mark II BL makes computer-aided design tools essential in initial design, design evaluation, per formance evaluation, and the writing of applications software.

We have developed a computer-aided design package for the Mark II BL system. It is based on a simulation using the process interaction approach and is imple mented in SIMULA. We have validated the simulation by comparing the performance of simulated applica tions software for a particular digital exchange with the performance of the real system. The simulator has been used to gain insight into the detailed be havior of the system and to test alternative strate gies and design modifications. A typical result of such an investigation is reported. We conclude by mentioning some proposed extensions to the simulator and its application in design.
Modeling the shearing and rehybridization process of DNA
Authors: Iyengar S. Sitharama
Published: March 2008

The physiological complexity of biological systems makes it very difficult to formulate hypotheses to explain their behavior and to test such hypotheses. Simulation models are precise statements of hypo theses ; hence comparing the behavior of a model with that of the corresponding real-world system is a way of testing the adequacy of the hypothesis represent ed by the model.

In this paper we use a simulation model to assess a hypothesis about the hydrodynamic shearing of DNA. A second model uses the output of the first one as an input. This latter model is being used to study the rehybridization process, which involves several unknown stochastic distributions.
Combining simulation and optimization to solve the multimachine interference problem
Authors: Garcia-Diaz Alberto , Hogg Gary L. , Tari Farhad G.
Published: March 2008

Optimal allocation of operations to automated ma chines becomes more complex if the labor force or the machinery is heterogeneous. The stochastic nature of the system must also be considered. Thus the problem is a stochastic, integer, nonlinear con strained-optimization problem. We solve it by con structing a simulation model of the operator/machine system and optimizing the simulator using several direct-search methods. The results provide optimal or near-optimal strategies for assigning operators of different skill levels to multiple classes of machines under constraints of operator availability.
Coping With Business Risk Through Probabilistic Financial Statements
Authors: Coats Pamel a K. , Chesser Delton L.
Published: March 2008

Today's financial environment is a broad arena with many uncertain economic, political, and operational factors. Because of this widespread uncertainty, corporations of all sizes are turning to financial forecasting models. For the most part, however, these models are deterministic and do not consider the riskiness, or likelihood, of the projections fed to them. Our model includes risk explicitly through the introduction of Monte Carlo techniques into a traditional corporate model. The resulting model produces both standard financial reports and the associated probabilities of occurrence, confidence intervals, and standard deviations. The model, which has been validated by historical comparisons, allows the planner to test many scenarios and deter mine the likelihood of satisfactory financial performance.
Simulating an Integrated Energy System
Authors: Mehrez Abraham , Sinuany-Stern Zilla
Published: March 2008

A simulation model of an integrated energy system can help a consumer decide whether to purchase a new sys tem for generating electricity, and what the size of its components should be. In the present study, the system consists of a liquid-metal magnetohydrodynamic (LMMHD) converter, parabolic sun collectors, and a heat storage unit. The system is in the final stages of development at the Ben-Gurion University of the Negev. The consumer in this study is a typical Israeli col lective farm (kibbutz). The consumer's aim is to reduce the expected discounted unit cost of electricity.
The Pennsylvania Corporate Tax Model
Authors: Allen I. Elaine
Published: March 2008

We have designed and constructed a corporate tax model for the state of Pennsylvania to aid in forecasting revenues and in performing policy analysis. The model contains two sub- models. One submodel is broad-based and includes corpora tions from all industrial sectors and firms of all sizes. The other submodel includes only the largest corporate taxpayers. The models are used for policy simulations including forecasting tax revenue and estimating the financial impact of new legisla tion.
Analog simulation of the human microvascular exchange system
Authors: Bert Joel L. , Pinder Kenneth L.
Published: March 2008

An analog model of human microvascular exchange of fluids and plasma proteins has been programmed and tested. The results agree well with clinical observations but less well with indirectly calculated terms. Examples show the model used to predict the dynamic response of the microvascular exchange system to body changes. These changes include a simulated heart attack and an allergic reaction.
Modeling continuous noise sources in digital simulations
Authors: Riggs Tom L. , Phillips Charles L.
Published: March 2008

Physical systems often contain subsystems that are "best" model ed as continuous random processes. When these processes are included in digital simulations, the statistics of the random num ber generator used in the simulation must be selected such that the continuous random process is modeled faithfully. In general the statistics of the random number generator will be drastically different from the statistics of the continuous random process. This paper presents the functional relationship between the sta tistics of the random number generator and the statistics of the continuous random process for simulations using two commonly employed integration methods.
2ND SECOND PLACE WINNER An interactive simulator for the designing of woven fabric structures
Authors: Shyong Shing-Kuo
Published: March 2008

Traditionally, point paper is used for the design of woven fabric patterns. Processing of point paper designing is tedious, time con suming and inefficient. What's more, the process is not cost ef fective from the viewpoint of marketing. Computerization is one way to resolve the problems inherent in the traditional process.

A microcomputer-aided textile design system has been developed which allows the visualization of woven fabric patterns (struc tures) either as traditional painted point paper or as a simulated graphic image of the fabric. The system contains routines for auto matic presentation of most basic weaves, such as plain, twill, basket, and satin. Other options are provided for the direct crea tion of more complex weaves or the manipulation of basic weave structures which leads to a more complex weave creation. Den sity of warp (lengthwise) and weft (widthwise) yarns can be se lected, and color can be assigned to each yarn. Once all the parameters are selected, the fabric pattern may be placed in disk files for later consideration or produced as hard copy from a color plotter.

The program has been implemented on a NEC Advanced Per sonal Computer using CPM 86 with GSX, CB 86 (compiled BASIC), and a Houston Instruments DMP 29 eight pen plotter. It is significant that the hardware cost is under $10,000. The pro gram has been used as a classroom teaching tool and, after con version to IBM-PC format, may be useful in industry.
Modeling noncoventional sampling schemes with a combined discrete-continuous language
Authors: Kilgore Richard A. , Kleindorfer George B.
Published: March 2008

Combined discrete-continuous simulation languages can pro vide a convenient and flexible structure for modeling a wide variety of nonconventional sampled-data control problems. Using the language SIMAN, it is shown how to model fixed, random, and signal-dependent nonconventional sampling schemes in cluding a nonsynchronous multirate system with a PID controller.
On the computation of digital filter coefficients
Authors: Shoucri R. , Benesch R.
Published: March 2008

Using the Taylor series expansion, a method is developed for estimating the value of a signal and its first derivative based on previous samples of the signal.
Quality assurance paradigms for artificial intelligence in modelling and simulation
Authors: Ören Tuncer I.
Published: March 2008

New classes of quality assurance concepts and techniques are required for the advanced knowledge-processing paradigms (such as artificial intelligence, expert systems, or knowledge-based sys tems) and the complex problems that only simulative systems can cope with. A systematization of quality assurance problems as well as examples are given to traditional and cognizant quality assurance techniques in traditional and cognizant modelling and simulation.
Epistemology of knowledge based simulation
Authors: Reddy Ramana
Published: March 2008

Combining artificial intelligence concepts with traditional simula tion methodologies yields a powerful design support tool known as knowledge based simulation. This approach turns a descrip tive simulation tool into a prescriptive tool, one which recom mends specific goals. Much work in the area of general goal pro cessing and explanation of recommendations remains to be done.
An expert system for FMS design
Authors: Mellichamp Joseph M. , Wahab Ahmed F. A.
Published: March 2008

Implementation of flexible manufacturing technology has created major problems for designers and engineers who are responsi ble for specification and design of flexible manufacturing systems (FMS). The FMS design task appears to be an excellent applica tion for expert system techniques. The objective of this research was to develop an expert system which could analyze the out put from an FMS simulation model, determine whether opera tional and financial objectives were met, identify design defi ciencies, and propose designs which would overcome identified deficiencies. An overview of the system is given and a case study is presented to illustrate how the FMS design expert system operates.
A port simulation model for bulk cargo operations
Authors: Park Chan S. , Yong Deok Noh
Published: March 2008

A port simulation model (Monte Carlo type) is presented to simulate the future economic port capacity to meet projected cargo demand. The first part of the model determines the effects caused by the port capacity expansion. The second part evaluates the port economics due to changes in the port capacity. The simulation model was tested by applying it to the actual port expansion followed at the Port of Mobile in Alabama.
Dynamic multi-level simulation of digital hardware designs
Authors: Ghosh Sumit
Published: March 2008

This paper presents the issue of dynamic multi-level simulation of hardware designs that addresses the problem of inefficiency associated with the conventional static multi-level simulation ap proaches as in ADLIB-SABLE (Hill 1980), DIANA (Demou and Arnout 1979), and SPLICE (Newton 1978). In this approach, digital sim ulation or verification (McWilliams 1980) of hardware designs is initiated at a high level of abstraction. When detailed results are required for one or more high-level components or for tracing the source of an error to any of the lower-level devices, the appropriate components are expanded into their lower-level implementations. Then simulation or verification initiates at that level. Following completion of execution at the lower level, con trol returns to the higher level. Consequently, only those sub parts of a digital design are selected for expansion and detailed simulation that are dynamically warranted by the higher-level simulation results. Unnecessary simulation effort may be elimi nated. Dynamic multi-level simulation or zooming is a generaliza tion of the swapping technique (Szygenda 1973) to functional and fault simulation and timing verification and to the differ ent abstraction levels in the hierarchy between the gate- and behavior-levels. This paper also addresses the implementation of zooming in the rule-based design verifier, RDV (Ghosh 1984), at Stanford University. That RDV uses Ada (U.S. Dept. of Defense 1983) as a hardware description language and simulation envi ronment (Ghosh 1985).
Prediction of receiver performance using the receiver design modeling simulator
Authors: Fox Richard L. , Neyens Patricia A.
Published: March 2008

The Receiver Design Modeling (RDM) simulator can construct a model to simulate receiver architecture. It has been used to model receivers such as the crystal video, superheterodyne, chan nelized, compressive microscan, instantaneous frequency mea surement (IFM), and Bragg cell. Example receiver simulation re sults are presented for the first four of these types.

RDM is implemented on a VAX 11/780 and written in FOR TRAN 77 using the VMS operating system.
Simultaneous estimation of several percentiles
Authors: Raatikainen Kimmo E. E.
Published: March 2008

In many simulation studies the performance of the modeled system is characterized only by mean values of the performance indices. However, the percentiles are more informative in sum marizing the performance. Several simultaneous percentiles, pre sented for example in the form of the boxplot, provide the analyst with better understanding of the system's behaviour.

The simultaneous estimation of several percentiles is a cumber some task. The extended P2-algorithm proposed in this study significantly reduces the computation of the estimation. The algorithm simultaneously estimates several percentiles without storing and sorting the observations. Empirical validation studies indicate the algorithm can be used in simulation studies.
A simulation model for ergonomic design of industrial processes
Authors: Kachitvichyanukul Voratas , Buck James R. , Ong Chee-Seng
Published: March 2008

This study examines the feasibility and potential benefits of using simulation to aid designers of large industrial processes. A demon stration of simulations is provided in the basic oxygen furnace shop and subsequent steel-making operations prior to rolling slabs. We explore three design situations: (1) a new processing technology, (2) the removal of bottlenecks in current operations, and (3) sensitivities of processing to equipment failures. Overall shop productivity and the time workloads of crews and indi vidual process operators are examined. Contrasts are made on these criteria between the current mode of operation and the potential design situations stated above through simulation ex periments. Results of these simulation experiments provide the basis for economic and ergonomic justification as well as indica tions for further improvements in the ergonomic facets of design.
Linguistic dynamic simulation A new approach
Authors: Câmara António S. , Antunes Paula C. , Duarte Pinheiro Manuel , Fonseca de Seixas Maria Julia
Published: March 2008

A new dynamic modeling methodology, SLIN, allows for the analysis of systems defined by linguistic variables. SLIN applies a set of logical rules which include base, tactical, strategic and structural change. To make the transition from qualitative to quantitative modes, logical rules are also used. SLIN is advanta geously implemented in a very high-level language such as PRO LOG. A simple ecological modeling problem illustrates SLIN's potential applications.
Programming for a nuclear reactor instrument simulation
Authors: Cohn Charles E.
Published: March 2008

This note discusses 8086/8087 machine-language programming for simulation of nuclear reactor instrument current inputs by means of a digital-analog converter (DAC) feeding a bank of series input resistors. It also shows FORTRAN programming for generat ing the parameter tables used in the simulation. These techniques would be generally useful for high-speed simulation of quantities varying over many orders of magnitude.
A hierarchical approach to computer animation in simulation modeling
Authors: Johnson M. Eric , Poorte Jacob P.
Published: March 2008

The trend toward animation in simulation yields interesting and exciting new techniques for simulation modeling. We discuss some of the benefits of using animation and propose a hierar chical approach to effectively use animation during all phases of the modeling process. We then illustrate the use of this hierar chical structure with a manufacturing case study involving the integration of AGV's with non-automated material handling devices.
SIMTOOLS: A software tool kit for discrete event simulation in Pascal
Authors: Seila Andrew F.
Published: March 2008

SIMTOOLS is a collection of procedures and functions that allow discrete event simulation programs to be easily developed in Pascal. The package, which implements the event view, has pro cedures for creating and deleting entities, managing lists or queues, event scheduling and sequencing, system tracing and data collection. It is useful for any model-building effort, but especially those which do not fall neatly into the class of queu ing networks where specialized simulation software is available. The advantages of such an approach include the ability to apply top-down design, self-documentation, portability and the fact that the only development software required is the Pascal compiler.
Radar target signal modeling and validation
Authors: Bertolini A. , Long J.H.
Published: March 2008

The performance of a radar system is greatly affected by the elec tromagnetic scattering properties of the targets to be tracked. A key target parameter is the radar cross section, defined as an effective area that scatters incident power in the direction of the radar receiver.

Two target modeling approaches used at Raytheon and their validation are described. One of the methods computes a com posite signal and equivalent cross section and glint from a num ber of discrete point scatterers. The other method, a statistical model, combines filtered and scaled noise sources from a ran dom number generator to produce the desired results.

The outputs presented include plots of sample radar cross sec tion, glint and angle tracking error histories as functions of target aspect and target aspect rate. There are also comparisons of results computed by the two methods, as well as with actual flight data.
A simulation study of hardwood rootstock populations in young loblolly pine plantations
Authors: Weise David R. , Glover Glenn R.
Published: March 2008

A computer program to simulate spatial distribution of hard wood rootstock populations is presented. Nineteen 3 to 6 year- old loblolly pine (Pinus taeda L.) plantations in Alabama and Georgia were measured to provide information for the simula tor. Spatial pattern, expressed as Pielou's nonrandomness index (PNI), ranged from 0.47 to 2.45. Scatterplots illustrated no rela tionship between pattern, species relative density, site prepara tion, or stand age.

Newnham's point pattern generator was modified to reduce execution time. Equations to predict program inputs as a func tion of PNI and desired number of points were developed for uniform, random, and randomly clumped populations. Total rootstock height distribution was fitted using a two-parameter, left- and right-truncated Weibull function. Crown area was de termined conditionally by total rootstock height. The simulator may be used to generate populations for evaluating different sampling methods for hardwood rootstock attributes or in in dividual tree growth and yield models.
Simulation of problems in propositional calculus
Authors: Rao V. V. Bapeswara
Published: March 2008

A simulation technique for the solution of problems in proposi tional calculus is described. An example is presented to illustrate the method.
Effects of relative humidity and yield on self-induced rainout from tactical nuclear explosions
Authors: Carhart R.A. , Policastro A.J.
Published: March 2008

We have studied the process of wet fallout from a tactical nuclear explosion due to scavenging of radioactivity by self-induced rain (rain produced by the explosion itself) using a numerical two- dimensional model of an axisymmetric cloud. Under mid-latitude summertime conditions and for yields of 20 to 100 kilotons, the model shows that self-induced rainout is not significant for low relative humidities, is very important for high relative humidities (> 80%), and is moderately important for relative humidities down to about 50%. When self-induced rainout occurs, it is heavy within a couple of kilometers of ground zero and peaks early in the episode. The model has successfully predicted observed radioac tive self-induced rainout for the Hiroshima and Nagasaki detona tions (both in the 20 kiloton range), and does not predict rain under conditions typical of U.S. tests in Nevada, where self-induced rainout has not been observed. The model is interesting as a hybrid of Eulerian and Lagrangian methods.
Simulation experiments for performance analysis of multiple-bus multiprocessor systems with nonexponential service times
Authors: Onyuksel Ibrahim H. , Irani K.B.
Published: March 2008

A simulation model (program) is constructed for performance analysis of multiple-bus multiprocessor systems with shared memories. It is assumed that the service time of the common memory is either hypo- or hyperexponentially distributed. Process ing efficiency is used as the performance index. To investigate the effects of different service time distributions on the system perfor mance, comparative results are obtained for a large set of input parameters. The simulation results show that the error in approx imating the memory access time by an exponentially distributed random variable is less than 6% if the coefficient of variation is less than 1, but it increases drastically with this factor if it is greater than 1.
Building intelligence into an autopilot using qualitative simulation to support global decision making
Authors: Vesanterä Pentti J. , Cellier François E.
Published: March 2008

In this paper, qualitative simulation is applied to reason induc tively about the behavior of a quantitatively simulated aircraft model, to determine on-line when a malfunction occurs in the quantitative model, to hypothesize about the nature of this malfunction, and to decide upon a global strategy that allows to operate (control) the quantitative aircraft model under the modified flying conditions.