bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hybrid techniques for generation of arbitrary functions
Authors: Rubin Arthur I. 
Published: March 2008

A discussion of the implementation of a true hybrid func tion generator module is presented. Included is a detailed description of how two of these modules, when used in conjunction with a hybrid computer, are used simultane ously to generate a continuous function of two variables, and how four modules are used to generate a continuous function of three variables. From a variety of possible con figurations, an optimum choice for a general-purpose HFG module is made, taking into account digital coefficient storage requirements and analog multiplier requirements. A detailed error analysis compares the errors produced in generating an arbitrary function using the HFG module with the errors produced by the classical hybrid (or purely digital) method of generating an arbitrary function by table look-up and interpolation for discrete values of the argu ment. The conclusion is reached that the hybrid method can be an order of magnitude more accurate than the classical discrete method for generating arbitrary functions and has further advantages in that the hybrid method does not require a 100% duty cycle in the digital processor for accurate function generation.
A remote terminal for accessing large hybrid computers
Authors: Ricci Fred J. , Nixon Floyd E. 
Published: March 2008

Hybrid computers can be controlled from remote termi nals which provide both alphanumeric and continuous waveform plots of the problem solution. For many scientific problems, hybrid computers have demonstrat ed computational speeds several orders of magnitude faster than digital computers. As the need for hybrid computation grows, more and more users will want ac cess to hybrid computers in order to take advantage of their speed and economy. This paper discusses the progress to date in the development of an experimental hybrid-computer network (EHCN) and describes a simula tion that has been performed using this network. The paper emphasizes the advantages of utilizing large- scale hybrid facilities accessed from remote termin als. Specifically, a network has been established between several locations. Details on the design and develop ment of the terminals associated with this network are presented and future applications of the network in government, industry, and universities are outlined. Transmission standards are being established so that additional locations which are either hybrid computa tional centers or remote terminals can be readily con nected. Access to a hybrid computer offers computer terminal users four distinct advantages which users will find highly beneficial: the economy of hybrid, analog graphics, high solution speed, and voice communica tion with computer specialists.
Dispersion of active pollutants in a shallow sea
Authors: Adam Yves 
Published: March 2008

Shallow coastal seas are the "priviledged" places for the dumping of wastes of all kinds: sewage, mud re leases, and chemical refuses are typical examples. In most cases, the shallow coastal seas are therefore very polluted. This paper describes a digital simu lation of the diffusion and transportation of pollu tants released in the shallow sea bordering Belgium. The model of course has much wider application. The principal new development in this paper is the method of integration of equations which describe such systems. The equations of the model have dominant advection terms, mixed derivatives, and nonlinear interaction terms, and are solved by a special predictor- corrector scheme consisting of three distinct steps. The mixed derivative is separated into second deri vatives along the grid axes and an auxiliary axis. The first two steps (implicit and locally one-dimen sional) form the predictor. The third one is the corrector, and it yields a consistent discrete approximation of the time derivative. The accuracy is 0(τ2 + τh + h2). A stability condition is derived and some problems in implementing the method are discussed. The paper concludes by presenting the results of a simulation of pollutant dumping in the North Sea near Ostend.
AQUARIUS: a simulation of communit water planning
Authors: Howard Richard A. , Wessler Eliot J. 
Published: March 2008

Simulation is used to give students of resources management an opportunity to form and evaluate a water resources plan. The focus of the planning problem is a mythical New England city called Aquar ius. In the first stage of the simulation, students work as a planning group and design a fifty-year comprehensive water plan. The students assume dif ferent roles and report to a director as they would in a real planning agency. In the second stage of the simulation, students use a computer model to simulate the operation of the water resources plan. They can observe the impacts of their plan over a period of years and revise the plan as needed.
Toward guidelines for designing experiments in queuing simulation
Authors: Turnquist Mark A. , Sussman Joseph M. 
Published: March 2008

The simulation of complex queuing systems is an im portant application for discrete-event digital simula tion. In many cases, the object of the analysis is estimation of steady-state measures (e.g., mean and variance of waiting time) for the system. The initial conditions in the system at the start of a simulation run may introduce a "bias" into the experimental re sults; several methods have been suggested to eliminate this bias. One common approach is a warm-up period at the beginning of the simulation run, during which no data are collected. The length of this warm-up period is determined by a tradeoff between the reduction in bias caused by the initial conditions and the increase in variance of the statistical estimates resulting from discarding the initial data, given that the analyst is operating with a fixed experimental budget. This paper explores the effect of initial conditions and the warm-up period on the design of simulation experiments for the simple case of a single-server queuing system with Poisson input and exponential service times. The experimental design problem is to determine the number of independent replications of a simulation run, the length of the warm-up period, and the length of the data-collection period, which together minimize the mean-square error of the estimated mean waiting time, subject to a budget constraint on the total number of customers whose progress through the system can be simulated. Optimal experiment design was found to be strongly affected by how busy the system is.
Simulating the consumption of gasoline
Authors: Wong Edwin , Venegas E.C. , Antiporta D.B. 
Published: March 2008

This study used econometric models to estimate the parameters of gasoline demand. The first model re lates gasoline consumption directly to income and price variables. The second model takes account of the market split between small and large cars, as well as the fuel-efficiency rating for each car type. Gasoline consumption is indirectly estimated through the relationship of vehicle miles traveled and price of gasoline and income. Both models allow for be havioral changes over time so that long-term response is greater than short-term response. Both models were fitted to Minnesota data and used to simulate future consumption under alternative price, income, and fuel efficiency scenarios. The effects of income level dominate the effects of price level in both models. Consequently, changes in real income level are important for forecasting future energy demands for automobiles in the state.
Catastrophe theory applied to ecological systems
Authors: Jones Dixon D. 
Published: March 2008

Catastrophe theory is a new field in mathematical topology that allows the formulation of comprehensive qualitative models of systems which have previously eluded rigorous mathematical formulation. Because the models have a topological foundation, many seem ingly dissimilar phenomena can be related to a common underlying topological structure. The properties of that structure can then be studied in a convenient form and the conclusions related back to the original problem. This paper provides an introduction to catastrophe theory and defines the principal condi tions required for its application. The basic prop erties of bimodality, discontinuity (catastrophe), hysteresis, and divergence are defined and illustra ted using the simplest structures of the theory. In this paper the spruce budworm/forest ecosystem of eastern Canada illustrates how catastrophe theory may be applied in ecology. With only a minimum of general descriptive information about the budworm system, a qualitative catastrophe theory model is hypothesized. This model is rich in its ability to provide predictions and insight about the global behavior of the system. To further check and verify the assumptions of this qualitative model, an exist ing detailed simulation model is analyzed from the perspective of catastrophe theory and is found to exhibit a basic underlying structure that is very similar to the catastrophe theory model. A detailed examination of the simulation model shows that catas trophe theory provides a consistent framework for analyzing and interpreting the behavior of this eco system.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.