bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear system simulation
Authors: Howard Bernard E. 
Published: March 2008

The ideas presented in this paper have evolved gradually over the past 10 to 15 years. Their genesis may be ob served in the three reports in the bibliography, covering work the author contributed to and directed. The approach has been used in many practical problems, including the simulation of guided missile systems at the large analog computer facility at Wright-Patterson Air Force Base, Ohio. The ideas have further evolved during the teaching of courses in numerical analysis at the University of Miami, a two week session at the EAI Princeton Computation Center in 1964, and extensive use of the Milgo Computa tion Center in Miami. The paper itself was prepared specifically for the meet ing at which it was presented. It was couched in general phase-space terminology, but the examples were all two dimensional. The reviewer kindly suggested that either the discussion be directed toward the phase plane, or higher dimensional examples be included. Following his sug gestion, higher dimensional examples have been solved which will be presented as a sequel, to avoid making this paper too long. In addition, one of the author's graduate students, Mr. Alex Koler, has been producing some inter esting results on the global topology of the phase plane of quadratic systems, which will be presented separately. The field appears fruitful for further investigations.
Acoustical simulation of a randomly fading Communication channel
Authors: Manders A.M. , Wait J.V. 
Published: March 2008

Experimental studies of fading RF communication chan nels are usually very difficult to perform under actual operating conditions. This paper describes a fading chan nel simulator which is easily constructed and flexible in operation. Using this simulator, modulation and coding techniques suitable for use in communication and ranging equipment can be tested and optimized for operation dur ing periods of severe fading. The simulator uses ultrasonic acoustical waves transmitted through water to achieve favorable changes in the space and time scales; typical fading rates are from 2 to 30 fades per second. The paper also describes simple hybrid statistical mea surement equipment used in studying the probability dis tributions and correlation functions of the received signals.
Simulation of frequency tracking loops with complex targets
Authors: Engle J.O. , Nisson C.J. 
Published: March 2008

This paper was written for the analog user to relate some of our experience in the area of signal processing (in this case signal processing by a radar receiver) to fit the theme of the Eastern Simulation Council meeting at which it was presented. "In the paper we attempted to give a complete but simple picture; by describing the signals and system, de veloping the simulation models, instrumenting the models with available computing equipment and finally by dis cussing simulation difficulties. (We wish that we had more modern equipment so that the instrumentation, particu larly of the dc models, could be more significant relative to state-of-the-art.)"
An example program for the determination of chemical rate coefficients from experimental data
Authors: Nesbit Richard A. , Engel Robert D. 
Published: March 2008

A program for matching experimental data to the com puted concentrations of various components of a dynamic chemical process is implemented. The digital subsection of the computer is programmed to execute a steepest descent search procedure. The analog section is programmed to solve the chemical rate equations which simulate the re action dynamics. These equations form a two-point bound ary value problem. The search procedure changes param eters in the rate equations, and it compares the computed concentrations to the experimental ones. The squared error is summed over all data points, and this sum is minimized by the search. Significant speedup of the solution to this type of problem is possible with the hy brid system due to the fast solution of the differential equations on the analog and the automated search pro cedure on the digital.
Application of process simulation to operator training and startup of a high-speed paper machine
Authors: Rounsley Robert R. 
Published: March 2008

Because of the complexity of operation of a paper machine, a simulation of operation would provide three avenues through which better startup and operation could be obtained: (1) engineering evaluation, (2) operator training, and (3) control-program evaluation. Prior to the startup of a new high-speed paper machine, a simulation of the stock system where the suspended fibers are formed into a sheet of paper was undertaken. Basic information on the steady-state and dynamic be havior of such a system was obtained on a highly instru mented paper machine having components similar to those of the new machine. The system was analyzed one component at a time to fit available theoretical equations with minor modifications. This allowed reasonable extrap olation and reassembly of the system to describe the new machine. An important factor in describing such a system was the transport lag in the pipelines. This facet of the simulation was accomplished with prewired Padé approximations of these lags. A second important characteristic in describing a paper machine in real time is the long time-constants involved in the rates of change. These may run as long as 10 minutes. A replica of the main control panels was constructed for use as a training aid for the operating crews of the new machine. The panels were programmed on the computer to respond to upsets and grade changes as part of an inten sive training program for the operators. Exploitation of the simulation system is still in progress. It is evident, however, that the smooth startup resulted from careful planning and effective operator training.
Highlights of two and one-half years of simulation efforts for deep submergence vehicles
Authors: Noble Tom F. 
Published: March 2008

This paper describes the highlights of two and one-half years of computer simulation effort on the deep submer gence vehicles Trieste II (Trieste), NR-1, and Deep Sub mergence Rescue Vehicle (DSRV). The work, which is still in progress, is being performed by Sperry Gyroscope Com pany under Navy and company-funded programs. Introductory material of the paper presents the simula tion program objectives, outlines the simulation facilities, and gives an overall simulation block diagram. The com puter simulations are being used in control-system, hull, and force-effector design efforts for the development of operational doctrine, as a tool for human engineering as sessment of displays, control input devices, and console layouts, and as a pilot training aid. Basic computation equipment consists of a hybridiza tion between an Electronic Associates 231-R analog com puter and an Ambilog Model 200 digital computer. Major facilities used to supplement these computers are a two- degree-of-freedom cab containing console mockup, pilot's control station, and an electronic flying-spot-scanner tele vision display generator. Major elements characterized in the simulations are six- degree-of-freedom boat dynamics; coordinate transforma tions for television display cues and real-world television pictures; various effectors, actuators, and sensors; and control computer equations. The body of the paper gives details on the use of the computer simulation in deep submergence craft design work. The design stages are broken down as: statement of design criteria, analysis of system parts, analysis of com plete system, synthesis of system design, fabrication of system hardware, test and evaluation, and improvement of design. Unique hull, effector, actuator, and control-system design problems encountered during the two-and-one- half-year simulation study are outlined.. This paper on simulation is concluded with a summary which indicates the need for highly integrated displays, control input devices, and control computers for deep sea craft.
Selected generalized integration techniques for analog computation
Authors: Hausner Arthur 
Published: March 2008

Generalized integration is a technique for generating ex plicit functions on an analog computer by solving the appropriate differential equations they satisfy. Setting up the solution of differential equations using the parametric technique is first reviewed. Two theorems regarding the capability of linear equipment in generating sums and products are stated, and their usefulness is illustrated with examples. Applications of the technique to generating high-degree oscillatory polynomials and rational functions (which require nonlinear equipment) are also described. The major advantage of the technique is achievement of great accuracy with minimum equipment in some cases. The major disadvantage is that, with time, errors may sometimes increase and may not be bounded.
Discussion of computer simulation techniques and comparison of languages
Authors: Tiechroew Daniel , Lubin John Francis , Truitt Thomas D. 
Published: March 2008

A draft of this paper was prepared for the Workshop on Simu lation Languages, Graduate School of Business, Stanford Univer sity, March 6 and 7, 1964. The paper has benefited from sugges tions from participants at the Workshop, particularly Michael Montalbano, and from projects carried out by students in the Graduate School of Business: H. Barnett, H. Guichelaar, Lloyd Krause, John P. Seagel, Charles Turk, Victor Preisser. The paper has also benefited from discussions held in connection with the Workshop on Simulation Languages, University of Pennsylvania, March 17 and 18, 1966. Characteristics of computer languages and software packages change rapidly. Some statements in the paper were originally intended for the situation current in March, 1964. Where signifi cant changes have occurred the text has been modified.
A comparison of two digital methods of EEG simulation
Authors: Bower Edward K. , Dwyer Samuel J. , Lago Gladwyn V. 
Published: March 2008

This article applies two very different approaches to the problem of digital simulation of a stationary time function, and compares their results. The first technique approxi mates the sampled time function by a Markov process of small order. The transition probabilities are estimated from samples of actual EEG, and a waveform is generated from these probabilities, using random number techniques. The second technique treats a time function as the out put produced by a linear filter on some random input. The transfer function of the filter and the distribution of the in put signal are then calculated. Graphs of the autocorrelation functions of actual EEG and both types of simulation are included for comparison. In the author's opinion, these graphs show the filtered- noise simulation to be somewhat superior to the Markov process simulation.
An example program for the determination of chemical rate coefficients from experimental data
Authors: Nesbit Richard A. , Engel Robert D. 
Published: March 2008

A program for matching experimental data to the com puted concentrations of various components of a dynamic chemical process is implemented. The digital subsection of the computer is programmed to execute a steepest descent search procedure. The analog section is programmed to solve the chemical rate equations which simulate the re action dynamics. These equations form a two-point bound ary value problem. The search procedure changes param eters in the rate equations, and it compares the computed concentrations to the experimental ones. The squared error is summed over all data points, and this sum is minimized by the search. Significant speedup of the solution to this type of problem is possible with the hybrid system due to the fast solution of the differential equations on the analog and the automated search pro cedure on the digital.
A new high performance computer d-c amplifier
Authors: Naylor Jimmy Ray 
Published: March 2008

A new computer d-c amplifier designed for very fast as well as for real-time analog/hybrid computation combines large bandwidth (30 MHz gain-bandwidth product) and high mid-band gain (68 dB at 10 KHz) with full ± 10V, 30mA output to 5.0 MHz, and low open-loop output im pedance (50 ohms at 10 KHz). High d-c gain (120 dB) and exceptionally low drift (50 pA/°C, 2.5 μV/°C ) is obtained with the aid of an inexpensive hot-substrate integrated- circuit preamplifier rather than with conventional chopper stabilization. A three-channel feedforward design employs an overcurrent-protected 30 mA class AB wideband output stage in the high-frequency channel, a feedback-equalized integrated-circuit operational amplifier as the intermedi ate-frequency channel, and the hot-substrate integrated differential amplifier stage as the low-frequency channel. Overcurrent protection makes the new amplifier short- circuit proof. Table 1 shows the performance of the new d-c amplifier.
Sample sizes and confidence intervals associated with a Monte Carlo simulation model possessing a multinomial output
Authors: Hurtubise Rolland A. 
Published: March 2008

A new classification of Monte Carlo digital computer simulations is suggested. The body of this paper centers on the determination of sample sizes and confidence intervals associated with a simulation model which has a multinomially distributed output. A brief description of a 'multinomial' Monte Carlo model is given. The theoretical considerations put forth are then verified on this model.
On the application of a variable transport lag
Authors: Nilsen R.N. 
Published: March 2008

This paper discusses various hybrid applications of a variable transport lag. A specific example, the simulation of a thermally controlled environment, is presented. In it the transport lag is due to the delay caused by having to move a mass of heated air by pump from the heating element into the environment. Various forms of heater control and delay function are presented and their effects on the system are described. Experimental results for various forms of heater con trol and transport lag variation are presented along with a discussion of the problems involved with this type of simulation. Finally, remarks as to possible methods of improvement and extensions are made.
Automatic patching for analog and hybrid computers
Authors: Hannauer George 
Published: March 2008

This paper describes the results of an investigation into the feasibility of an automatic patching system for an analog or hybrid computer. The objective of the study is to reduce the number of switches required to a "rea sonable" number. Actual design of hardware is not con sidered. The final result is a "paper" design, which is evaluated by attempting to program several problems to see if enough paths exist. The proposed design uses about 8,000 switches for an EAI-680-sized computer, which is far fewer switches than are required by any previously proposed system. The evaluation shows that this system is more than adequate and that, in fact, about 2,000 switches could be saved by modifying the design slightly.
Generalized finite-difference approximations f or the parallel solution of initial value problems
Authors: Vichnevetsky R. 
Published: March 2008

Methods used in analog computation for the parallel- finite-differences solution of partial differential equations have been almost universally based on the "classical" derivation of finite-difference approximations. That is, the space-dependence of the approximate solution is lo cally assumed to be appropriately represented by a Tay lor (or polynomial) truncated series of low1, or higher7, order. Although known to introduce higher truncation errors than the use of other functional series2,3, this re striction has been mostly accepted for reasons of con venience because no simple method for obtaining more general approximations was available in practice. We show in this paper that completely general finite- difference approximations of linear partial differential operators in space, based on functional (rather than, but including, polynomial) approximations, can be easily ob tained in a direct method involving only the inversion and multiplication of constant matrices. One of the drawbacks of the analog computer imple mentation of equations obtained by application of the method presented here is that it requires more attenu ators than the classical low-order method. However, as suggested by Deiters and Nomura3, this is alleviated in a hybrid computer by introducing at discrete time inter vals the higher-order terms as digital corrections super imposed upon an analog low-order implementation. Examples of the derivation of generalized finite-differ ence equations are shown for the representation of the Laplacian (diffusion) operator in circular (r, θ) and linear (x) coordinates.
Padé approximations and analog computer simulations of time delays
Authors: Holst Per A. 
Published: March 2008

The Padé approximations 1 of e- x are reviewed in con nection with their application in simulations of transpor tation delays (time delays) by analog computers. The approximation coefficients are specified in terms of the order of the approximations, and recurrence relation ships are established for the most common types. Analog computer circuits are given for general Padé approxima tions of any order and type, together with practical exam ples of both constant and variable transportation delay simulations. Special attention is paid to the zero-variable delay time constant, and circuits are given for this type of application. The performance of the Padé approximation circuits is discussed in terms of phase error and amplitude char acteristics for sinusoidal signals, together with rate-of- change measures in connection with step-response analy ses. Conclusions are drawn as to the order and type of Padé approximation to be selected to meet given per formance requirements. A table of Padé approximations up to the 12th order is included.
Engineering applications of finite automata
Authors: Lutter Bernard E. , Huntsinger Ralph C. 
Published: March 2008

The study of automata has been acquiring increasing im portance for engineers in many fields. For some time, the capabilities of these automata have been of the greatest interest to logicians and mathematicians. However, the expanding literature on the use of finite automata as probabilistic models demonstrates the growing interest in the application of these mechanisms to engineering phenomena. We, the authors, became interested in these probabil istic models in an effort to develop a general self-adaptive control scheme based on the prediction of the future of the process to be controlled. Conceivably, an adequate model of a particular process could be generated by simply observing the process parameters. With this goal in mind we began an investigation of several different modeling techniques. The ability to model stochastic data was our primary concern. We feel that the results of several modeling experiments presented here may be of interest to our readers, and we hope to encourage the use of these techniques, especially in control applications.
Determination of the time-domain equivalents of higher-order Laplace transfer functions by analog computation
Authors: León Jesús , Herrero Emilio E. 
Published: March 2008

In the theory of optimal inventory control, a class of com plex Laplace transforms arises for which the theoretist needs to know the form and shape of the time domain equivalents. Several methods have been used to obtain these time domain equivalents. In this paper simulation by analog computer has been used, and a low-order approximation of higher-order transfer functions has been simulated. The accuracy of this low-order approximation has been de termined by use of time domain plots.
A user specifies software for hybrid computing
Authors: Krasno L. 
Published: March 2008

The article discusses a subject about which much is said and little is written—the writing of specifications for hybrid software. The basis for the article is an Aerospace Corpora tion Hybrid Computing Center study of the upgrading of the digital portion of our hybrid system. In the process of discussing the study, a philosophy for writing specifications for hybrid software is presented. The philosophy, herein called "Functional Specifications," can be used by any facility regardless of its requirements. With Functional Specifications, a facility states only its require ments and leaves the designing of the system to the vendor.
Continuous Flow Charts
Authors: Gieszl Louis R. , Rieman Frank C. 
Published: March 2008

The current concept of the flow chart for documenting a computer program seems to be more heavily influenced by its business data processing background than by its mathematically oriented inception. The result of this is a loss of definition which inhibits further developments in program documentation. This paper proceeds from an analysis of the structure of a program and how this structure is represented by a flow chart to derive an extension of this: continuous flow charts. A continuous flow chart, which may be constructed from a conventional flow chart by removing its points of (flow) discontinuity, is shown to be a form of docu mentation ideally suited for large-scale programs that by their nature involve complex logic (such as a war-game simulation). The motivation for continuous flow charting is the pos sibility of dynamic documentation arising from a set of such flow charts. That is, the requirements suggested in this paper for a flow chart to be called continuous pro vide an inductive definition for the members of a set of levels of documentation of a simulation (such that the ease of a user's level to level transition of understanding [the logic depicted] is maintained). Such a set would have, at its highest level, a flow chart picturing the overall logic of the entire simulation, and, at successively lower levels it would contain flow charts describing smaller portions of the program in greater detail. An actual machine-language program would constitute the lowest level of documentation in this set. Since the creation of such a set of continuous flow charts can be started from either the highest level or the lowest level, then this procedure should serve equally well for either developing a complex program from its most basic logical conception, or for documenting such a program as has already been written.
The lunar module simulator
Authors: Brown Malcolm O. , Waters John G. 
Published: March 2008

The Lunar Module Simulators (LMS) in Houston and at Cape Kennedy are highly complex devices used for flight crew training and systems engineering evaluations to support the Apollo missions. Each of the two simulators consists of a three-machine digital computer complex, associated digital conversion electronics, a crew station that is an accurate replica of the Lunar Module cockpit, an infinity-optics visual display system, and an instructor-operator control con sole.