Abstract: This paper describes a visual simulation technique by which fully computer-generated perspective views of three-dimensional objects may be produced. The method is based on a relatively simple geometric modeling technique for the mathematical representa tion of the three elements essential to the picture- taking process, namely, a camera, a light source, and the object or objects to be photographed. Once these three basic components have been defined, geometric ray tracing is employed to compute a "picture" of the object as it appears in the simu- Zated camera. In essence, individual light rays are traced from their source to the surface of the object. The reflected component of each ray is computed and traced to its point of intersection with the film plane. Thus, each reflected ray pro vides the intensity at a single point on the pic ture, and, when a sufficient number of points have been computed, the entire area of intensity data may be displayed on a cathode ray tube. Several examples of the pictorial...

Abstract: A class of algorithms known as random search methods has been developed for obtaining solutions to para meter optimization problems. This paper provides a guide to the literature in this area, while describ ing some of the theoretical results obtained as well as the development of practical algorithms. Included are brief descriptions of the problems associated with inequality constraints, noisy measurements, and the location of the global optimum. An attempt is made to indicate types of problems for which random search methods are especially attractive.

Abstract: Historically, one may identify many of the hybrid and analog methods for partial differential equations with the &dquo;methods of lines,&dquo; which were first described in the late 1920’s and early 1930’s. Several papers published then were concerned with problems in two independent variables, in which the technique of approximation by finite differences was used to reduce the partial differential equations to systems of ordinary differential equations.20,28 The original intent of these methods was to provide a means of paper-and-pencil solution or to approxi-

Abstract: This simulation language survey is a followup of the survey published in SIMULATION, in May 1970, p. 225. The previous report generated much inter est, criticism pro and con, and most importantly some additional responses. Consequently the responses summarized below, including the 30 re sponses from the original survey, now total 103. Responses were solicited by direct request, the generous efforts of others (notably Ira Key of Southern Simulation Service, Inc.), and a "Dear John" letter published in the October 1970 issue of SIMULATION.

Abstract: Mr. Blumberg has had extensive experience in the direction of major projects in urban and community planning and in the development of simulation models for regional and urban analysis. He has been a consultant to a number of government organizations such as the Office of Economic Opportunity, the Advanced Research Projects Agency, the City of Toronto, the Province of Ontario, Canada, the Canadian Manpower Development Commission.

Abstract: screening sequence was developed as a tool for redesigning the screening procedure to maximize the total number of patients that can go through the system and to minimize patient delay by varying the number and characteristics of the components of the system as well as by varying the arrival pattern of patients. The simulation permits a user to define and manipulate the elements in the system and the activities performed by these elements. The effect of each modification on the system’s performance can be directly observed through plots and tables displayed at the user’s terminal.

Abstract: ROBERT W. LAWLESS is Director of the Doctoral Program in Business Administration and Associate Professor of Quantitative Management Science at the University of Houston. He holds an AS in chemistry from Lee College, a BS in mathematics from the University of Houston, and a PhD in Industrial Engineering from Texas A & M University. His experience includes positions as Researchs Instrumentation Engineer at Monsanto Company, Texas City, Assistant Research Engineer at the Texas Transportation Institute, Assistant Professor of Industrial Engineering with Texas A & M University, Consultant to the Operations Analysis Branch of the National Aeronautical and Space Administration, and consulting with the Health Resources PZanning Unit of the Texas HospitaZ Association.

Abstract: Electronic analog computers and the applications of analog computations and simulations have grown and expanded fast, attaining age, maturity, and technical sophistication these days. Remember a few years ago--when paper presentation and panel discussions abounded in gloomy predictions and dim prognostications for this type of computing technology? It appears most of these visions of the analog computer’s impending demise carried along a lot of Mark Twainian exaggeration. Now the general realization of almost ever-present time-and-money limitations have turned a good many all-digital users to analog and hybrid computers. Simulation has rapidly become

Abstract: The trajectories of liquid droplets and dust parti cles in a wet cyclonic scrubber were studied via mathematical modeling on TR-20 analog computers. This simulation study was restricted (1) to two- dimensional flow and (2) by the assumption of Stokes' Law behavior.The penetration of spray droplets into the gas flow field and the time of effective contact with the gas field at high relative velocities were found to be critically dependent on the diameter of the spray droplet and on the angle of injection, in addition to the anticipated dependency on gas flow rate and on projection velocity of the spray particle.It was found that for small particles (<50μ) the drag forces were so high relative to the initial forces that only insignificant penetration of the vapor body occurred, even at a projection velocity of 200 feet per second.At an average rotational air velocity of 50 fps a maximum probability of effective interception and impaction of spray and entrained particles occurred in the region of a spray ang...

Abstract: ISL-8 is the first single precision, parallel interactive simulation language available for a minicomputer. This paper illustrates ISL-8 programming procedures and opera tional conveniences for solving a second-order differential equation and three nonlinear problems from science and engineering. The relationship to integration step size and computational accuracy is also shown. The article con cludes that ISL-8 as implemented on any of the 4K PDP-8 family of computers can accommodate up to 25 nonlinear differential equations at computational speeds 10 to 50 times faster than languages using floating-point methods. (8K systems can accommodate up to 100 nonlinear equa tions.)

Abstract: Compufilms is a computer-generated animation tech nique developed jointly by Pennsylvania Research Associates Inc. (PRA) and film producer, Stanley Rose. A medium-scale general-purpose digital compu ter (RCA Spectra 70/46) is used to generate display instructions for a Digital Equipment Corporation PDP 8/338 connected as a satellite computer via telephone lines. The DEC 338 CRT display is photographed with a motor-driven motion picture camera having a "single frame" feature. Special effects and color are added at this point.The basic movie generating softwave was written at the Moore School of Electrical Engineering, Univer sity of Pennsylvania, on sponsored projects. The developers have been able to extend the use of this software and combine it effectively with special animation and cinemagraphic processes to create Compufilms. This article describes the system and its operation, and illustrates its use as a practi cal animation process.

Abstract: An essential part of almost all air-defense computer simulation models is the visibility subroutine. This subroutine performs the necessary computations and provides the data required to determine whether enemy aircraft or missiles may be detected by stationary ground-based air-defense system sensors- that is, whether they are within sensor range and whether their visibility is obstructed by terrain irregularities and/or the curvature of the earth. This paper presents a new approach to the visibility subroutine, entitled MAVD (Minimum AltitudeVisibi Zi ty Diagram). MAVD provides a visibility subroutine which could be incorporated into existing models relatively easily. The authors believe that it would result in a more realistic simulation and provide a significant reduction in computer time, in comparison with other simulation methods with which the authors are familiar.

Abstract: Hybrid Monte Carlo Techniques for the solution of elliptical and parabolic partial differential equa tions have been developed. This paper primarily con cerns the implementation of these techniques with a small, general-purpose digital conputer, a modest analog computer, and a minimal interface.

Abstract: This paper investigates the stability of tubular reactors by both theoretical and computational techniques. Liapunov's second method using a Liapunov functional of the general norm is used to show that tubular reactors without diffusion and without temperature effects and reactors with diffusion and without temperature effects are globally, uniformly asymptotically stable. The theorem fails for reactors with temperature effects. The results of computer simulations show that the system with temperature effects is not uni formly stable.

Abstract: E. DAWSON WARD was born in 1942 in Pittsburgh, but considers himself a native of Kansas City. He received his BS degree in Mechanical Engineering in 1964 from Kansas State University and the SM degree from MIT the foZZoroing year. During the summer before entering MIT he was employed by E. I. duPont de Nemours and Company in vilmington, Delaware. Upon comp Ze ting the SM degree, he joined the faculty at Kansas State, where he taught for three years and was engaged in research in the area of room air distribution. During the summer of 1967 he was empZoyed by the Detroit Edison Company, for whom he developed a simulation of

Abstract: The Federal Aviation Administration, at its National Aviation Facilities Experimental Center, has recent ly completed a new air traffic control system Digital Simulation Facility. The facility allows for improved real-time systems simulation and is currently being used to support two important pro jects aimed at improving control and safety of air traffic: It is being used to evaluate the inter action between a proposed airborne collision avoidance system and the air traffic control system, and to validate the various levels of automation in the air-terminal automation development program. The facility was developed for simulating present and proposed air traffic control systems and has twelve digital displays, five used as pilot consoles and seven as controlleer consoles. Each is equip ped with data entry devices for communicating with the computer which controls the simulation. This article describes the operation of the system, the hardware which comprises it, and the software required to control the equipment, to simulate air craft flights, and to collect and reduce data. Advantages of the new simulation facility over prior ones are discussed, as are plans for its use and expansion. The new facility provides an environment for con ducting simulations required in developing improved air traffic control systems to meet the needs of our increasing air traffic. Language: en

Abstract: programs (FN2SET) is used in the INITIAL segment of a CSMP program to add an identifier index to each set of data representing a function of two variables. The second subprogram (FUN2) performs table search of the X and Y input data arrays and two dimensional linear interpolation. FUN2 can be used anywhere in the CSMP program after FN2SET has been used to set up the data arrays. The table search method used in FUN2 was made very fast by using two table-search indices. These search indices are used as the starting points in the table searches of the X and Y input data arrays. If the X or Y inputs are not in the same intervals between X breakpoint pairs or Y curve values that they were in for the preceding entry, the search indices are incremented either up or down until the proper intervals are found. The final values of

Abstract: The mathematical model of the diode proposed in this investigation for the analysis of nonideal poly phase converters has finite forward and reverse resistances. Since current-dependent diode impedances exist at all times, only one set of piecewise-linear time-invariant state-variable equations is required to describe the nonideal polyphase diode converter completely. A digital computer solution of the state- variable equations was obtained to verify the inte grity and tractability of this method of analysis.

Abstract: an approximate solution which is equivalent to a certain number of terms in a Taylor series, and an approximate evaluation of the error in this solution. In some cases this error estimation is equivalent to evaluating the next term in the Taylor series, and is therefore fairly accurate and can be combined with the original solution, thus increasing its order of accuracy. It would be untrue to say that in such a case the error was known accurately as the magnitude of the last term included will normally be considerably greater than the error. This is not to say that such techniques do not have their uses. It is not uncommon for a series to be evaluated until the last term included falls below a specified magnitude. What must be remembered is that this magnitude gives

Abstract: neer from April 1948 to October 1949. He then joined the General Engineering Laboratory (now part of the GE Research and Development Center) as a development engineer, and held this position from 1949 until 1956. During this period he engaged in advanced development of nuclear, industrial and military control including position servos, regulated power supplies, motor and generator voltage, current, frequency, and/or speed regulators involving magnetic amplifier and electronic amplifier circuits.

Abstract: Medical College of Virginia, and at Stanford University, where he received the PhD in 1956. After a year’s postdoctoral work in Texas, he returned to Michigan Tech to teach chemistry until 1962, when he was appointed head of the newly-organized Department of Biological Sciences. In 1968 he gave up his administrative duties to return to full-time teaching and research on analysis and synthesis of aquatic ecosystems. Dr. Spain’s interest in simulation has evolved from the hobby stage. which resulted shortly after the department purchased its first Olivetti Programma 101, to a stage where a considerable amount of his time is now spent in writing papers and developing coursework on the subject of simulation for undergraduate science students. The tremendous potential for developments in this field could in the future further distract Dr Spain from the skiing and trout fishing that originally brought him to Michigan’s great Upper Peninsula.

Abstract: Recently, Monsanto Company’s engineers found themselves in an enviable position of being able to select which simulation tool they would use rahen doing dynamic simulations. The choices open to them taere Monsanto Company’s hybrid computer and S/360 CSMP operating on the company’s IBM 360/65 digital computer. The hybrid system was a Control Data 1700 digitaZ computer coupled to two EAI 680 analog computers through a Control Data supplied interface. This communication will document some of the facets of the decision that led Monsanto to go exclusively the digitaZ simulation route.

Abstract: A method is given to eliminate hidden lines from line drawings of volumes whose surfaces are a union of polygons. Projected polygons are tested pair- wise for overlap by looking for lines with the property that all vertices of one polygon lie on one side of the line and all vertices of the other pdygon lie on the opposite side. When a pair is found to overlap, hidden line endpoints are found by searching a table that was constructed in the test for overlap. Some results of a program written to demonstrate the method are given.

Abstract: ALLAN G. LINDGREN received his BEE degree from the University of Minnesota in 1964 and went to Control Data Corporation the same year. He is a Project Manager in the Design Automation Department, where he is responsible for the development of computer-aided circuit design capabilities and the design of computer circuitry. Initially Allan wrote programs for the computer solution of circuit equations for specific circuits. As general programs became available he developed the computer-aided design capability for use by Control Data circuit designers. Allan spent some 23 years in Uncle Sam’s Army as an Artillery officer, retiring in 1962 with the rank of Major after having served in three wars.

Abstract: Every simulation requires a good static check to be performed to insure that,initially, the equations being simulated match those of the analysis and, subsequently, to be sure that the analog computer's patchboards remain free from wiring errors. Custom arily the static check is prepared by hand using a desk calculator, since the time required for pro gramming a "one-shot" digital program is typically not a good investment. However, by utilizing the capabilities of a suitable simulation language (such as CSMP or DSL/91), digital static checks can be made economically in less time than that required for a hand-calculated check, especially in the case of hybrid computations. Also, with a little ingenuity, the efficiency of hybrid simulation can be greatly increased by combining the static-check calculation and automatic analog setup via the simulation-language static check. (Familiarity with analog programming and the use of simulation languages is assumed.)

Abstract: EVERETT L. JOHNSON, CSSC GORDON BOLTON, SWSC JOHN LEDGER, UKSC The Boeing Company tockheed Electronics Company University of Manchester Augusta, Kansas s .. ,;~ ,j a ~! r,r, ,,vv,~ r~ , , a , 4 , s&dquo; . ~,,t r;., e, , a~r, ~,,,~,,in a ,a= La Porte, Texas ~n ~a ,~,, ~P,,,~3.~~f~ rav, ,r ~~~’:~ ; ~ , ~tq~ ! ~c , ,wl, s r,;~ ~a,~ c~l, ®, i~lq ,r 499&dquo;p,9 ~ ~ p~ ~V oo&dquo;&dquo;,ld, !!’’’!,,! Manchester, England

Abstract: September, 1969 that Mr. Callan began working with CRT displays. Since then, however, he has devoted most of his working time and energy to programming the LDS-1 graphics system. Probably the most obvious of his achievements was the preparation of five demonstration programs for his company’s Spring Joint Computer Conference exhibit (1970). One of these programs, on the creation and editing of printed circuit boards, was chosen as the basis for a paper at the Fall 1970 Digital Equipment Computer Users Society (DECUS) symposium.

Abstract: (abridged): many of the present problems in automatic control economic systems and living organism can be converted to parameter optimization in stochastic systems. foremost among these problems are questions of the control of systems with incomplete information, learning problems, adaptive control, identification of objects, and the automatic synthesis of objects. such problems can be solved by stochastic approximation methods which are, essentially, iterative procedures. for this reason, great attention is paid to these methods in connection with practical applications. they were elaborated as a purely mathematical problem a long time ago and a number of valuable results are now available. not only the conditions of convergence,but some properties of the asymptotic speed of convergence are also known. in some cases, however, a disadvantage of stochastic approximations is the slow convergence to the desired extreme of the optimality criterion. at present, utmost attention is devoted to the elimination of these undesirable properties. unfortunately, practical requirements are often in disagreement with the assumptions from which we start when seeking more effective algorithms. (...);