Analog Simulation of Rigid Link Mechanisms

1967 ◽  
Vol 89 (2) ◽  
pp. 199-204 ◽  
Author(s):  
R. F. Timm
Keyword(s):  
Analog Circuit ◽  
Analog Computer ◽  
Analog Simulation ◽  
Rigid Link ◽  
Four Bar Linkage

This paper describes a procedure for simulating rigid link mechanisms on an analog computer. The computer circuit enables one to record all kinematic variables, i.e., displacements, velocities, and accelerations, for any point on the mechanism using conventional, commercially available computing elements. Also included in the paper is a scaled analog circuit for simulating velocities and displacements for the four-bar linkage, along with records of these parameters from the author’s simulation.

Dynamic Response of Surface-Moored Vertical Barrier to Wave Action by Analog and Digital Simulation

1974 ◽  
Vol 96 (1) ◽  
pp. 335-342
Author(s):  
J. R. Fowler ◽  
E. I. Bailey
Keyword(s):  
Theoretical Model ◽  
Digital Simulation ◽  
Nonlinear Problems ◽  
Analog Computer ◽  
Two Dimensional ◽  
Test Program ◽  
Analog Simulation ◽  
Vertical Barrier ◽  
Amplitude Data ◽  
Lab Test

The two-dimensional dynamics of an oil containment barrier, which was designed to have very low tensile loads due to current and waves, were simulated with a theoretical model. The model was solved on both analog and digital computers, and a lab test program conducted to verify the model. For nonlinear problems such as this, for which “exact” solutions do not exist, the analog computer has many advantages, principally rapid parameter studies and convenient plotting output, plus giving the engineer a real time “feel” for the problem. The problem treated here was especially well-suited to analog simulation. Charts and graphs present maximum force and amplitude data, and experimental verification of the solution was obtained from wave tank studies.

The Accuracy of One Method for Mechanism Simulation by Electronic Analog Computer

1965 ◽  
Vol 87 (2) ◽  
pp. 235-242 ◽  
Author(s):  
Robert E. Keller
Keyword(s):  
Computer System ◽  
Analog Computer ◽  
Four Bar Linkage

A method for the simulation of mechanisms on the electronic analog computer has been developed. In this paper a detailed discussion of the accuracy of the simulation is presented. Particular attention is given to the accuracy of the simulation of the simple kinematic link. Consideration is also made of the accuracy of the simulation when utilized in the study of complete mechanisms, for example, the accuracy to be expected of coupler curves for the four-bar linkage as generated by the simulation. Sample curves are given and their accuracy discussed. General relationships for achievement of an optimal computer system are presented.

Analog Simulation of a Bilinear Hysteretic System Undergoing Random Vibration

1969 ◽  
Vol 91 (4) ◽  
pp. 1051-1056
Author(s):  
R. N. Brown
Keyword(s):  
Computer Simulation ◽  
Probability Distribution ◽  
Random Vibration ◽  
Analog Computer ◽  
Equivalent Linearization ◽  
Level Crossing ◽  
Analog Simulation ◽  
Physical Behavior ◽  
Hysteretic System ◽  
Level Crossing Rate

An analog computer simulation is used to substantiate an equivalent linearization analysis of a bilinear hysteretic system undergoing random vibration. An interpretation of the physical behavior of the system is presented. Quantities useful in failure prediction—the average level crossing rate and the probability distribution of the displacement—are also measured, and it is shown that the hysteretic system can have a longer life than a linear system based on a low level approximation.

Improving the analog simulation of partial differential equations by hybrid computation

SIMULATION ◽  
1968 ◽  
Vol 11 (2) ◽  
pp. 73-80 ◽  
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Adaptive Sampling ◽  
Analog Computer ◽  
Correction Function ◽  
Partial Differential ◽  
Analog Simulation ◽  
Error Corrections ◽  
Hybrid Computation ◽  
Truncated Fourier Series

The conventional analog computer simulation of partial differential equations is very useful, especially where fast repetitive runs are desired. However, the rough approxi mations in the space derivatives obtained by differencing one or more of the space variables in a time-independent equation can lead to considerable error. We propose here several methods of correcting this error which require hy brid computation for their meaningful use. The integrator outputs from each "cell" of the analog computer are sampled simultaneously, and these sample values are then processed numerically in the digital com puter to produce corrections to the derivative first-order approximations being mechanized on the analog com puter. These corrections are supplied to the analog solu tion through the DAC as a continuous correction function throughout the time transient. We have, so far, found that the best method of computing these corrections is based on the truncated Fourier series. We also found that axis transformations can be used very simply and effectively to compute better derivative approximations. By the transformation, samples are bunched in the more active and spread in the less active space regions in a type of adaptive sampling. The digital computer easily computes the necessary transformations and automatically sets the analog potentiometers. Using these two methods, together with some calcula tions to prevent error-noise corruption, we obtained error corrections of the order of 15 to 30 percent in some de rivative approximations now in common use.

BEYOND SPICE, A REVIEW OF MODERN ANALOG CIRCUIT SIMULATION TECHNIQUES

1998 ◽  
Vol 09 (03) ◽  
pp. 783-805
Author(s):  
TROND YTTERDAL ◽  
TOR A. FJELDLY ◽  
MICHAEL S. SHUR
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Analog Circuit ◽  
Circuit Simulation ◽  
Continuation Methods ◽  
Relaxation Methods ◽  
Analog Simulation ◽  
Simulation Techniques ◽  
Circuit Decomposition ◽  
Difference Time

We present a review of modern analog simulation techniques based on time- and frequency-domain algorithms. For time-domain techniques, important topics such as circuit decomposition, relaxation methods, latency, multirate integration, continuation methods, parallel algorithms, and finite difference time-domain methods are discussed. Frequency-domain simulation techniques included are harmonic balance, harmonic relaxation, harmonic-Newton, spectral balance, methods for quasiperiodic circuits, and device modeling for frequency domain simulators. Also included are examples of modern simulators.

Analog simulation of satellite times-in-view

SIMULATION ◽  
1967 ◽  
Vol 8 (2) ◽  
pp. 105-110
Author(s):  
Roger N. Bryan
Keyword(s):  
Real Time ◽  
Digital Computer ◽  
Satellite Orbit ◽  
Analog Computer ◽  
Paper Strip ◽  
Analysis Tool ◽  
Analog Simulation ◽  
Satellite Geometry ◽  
The One ◽  
Orbit Geometry

During the planning stages of any communication or com mand/control system utilizing satellites, it is necessary to examine the ground-terminal/satellite geometry for many proposed configurations in order to find the one most suitable. By "most suitable," I mean the configuration exhibiting the greatest ground-terminal-to-satellite acces sibility as demonstrated by a maximum time-in-view. The procedures I describe in this paper provide a means for rapidly generating ground terminal/satellite visibility records via an analog computer simulation of the Earth's surface/satellite orbit geometry. The analog simulation has several significant advantages relative to similar digital computer approaches-(1) it is significantly faster (easily 15,000 times real-time) and less expensive to operate; (2) the output, ink-on-paper strip-chart recordings, is directly interpretable without further data reduction; (3) system parameter changes are readily introduced while a simula tion is in progress; (4) the Systems Analyst can maintain a decidedly greater rapport with his configuration analysis. The disadvantages are: (1) diminished accuracy, and (2) exclusion of Earth/orbit non-linearities and anomalies—in a real-time tracking or scheduling simulation, these dis advantages are serious; in a systems analysis tool such as this time-in-view simulation, they are not of great con sequence. I have devoted the first five sections of this paper to a description of the development of the vector-matrix model underlying the simulation. The sixth section describes the mechanization of the model using an electronic analog computer. The equations from which the computer potentiometer settings are derived are quite tedious to manipulate man ually—even aided by a desk calculator. In an appendix, I describe the simple digital computer (in my case, a RE- COMP II) program used to obtain the desired potentiom eter settings. It strikes me that, while lack of simultaneity in the usage of the analog and digital machines precludes the use of the word hybrid, we may validly coin the expression "syner getic computing" to describe this simulation.

Study of Gas Reservoirs Subject to Water Drive on Electronic Differential Analyzer

1961 ◽  
Vol 1 (04) ◽  
pp. 287-297
Author(s):  
H.D. Yoo ◽  
D.L. Katz ◽  
M.R. Tek
Keyword(s):  
Water Flux ◽  
Gas Storage ◽  
Analog Computer ◽  
The Body ◽  
Simulation Technique ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Analog Simulation ◽  
Storage Reservoirs ◽  
Differential Analyzer

Abstract The behavior of gas-storage reservoirs subject to water drive is investigated through analog simulation on an electronic differential analyzer. The simulation technique developed on an LM–10 computer permits the prediction of reservoir volume or pressure resulting from the movement of water in the surrounding aquifer. The method developed on the analog computer consists off-setting up an appropriate transfer-function circuit and feeding the arbitrary time-varying boundary conditions as an input signal. The input may be specified as gas reservoir pressure, pore volume or the water flux. Several cases studied include an isolated gas reservoir on a limited aquifer, interference among three reservoirs adjacent to a common aquifer and the growth of gas-storage volume on an aquifer. It is concluded that the method developed on an electronic differential analyzer provides an excellent technique to simulate and investigate the behavior of gas reservoirs subject to water drive. The agreement between the reservoir performance as predicted from the simulation technique and as measured from actual field data is found to be better than the range usually encountered in predicting water-drive behavior. Introduction It is generally known that some gas-storage reservoirs are located on top of blanket sands of large extent, saturated with brine called aquifers. Because the volume of the body of water associated with aquifers is usually very large and water is compressible, the cyclic pressure variations encountered in normal storage service inevitably cause unsteady, compressible flow conditions in the adjacent aquifers. The solution to radial diffusivity equation for a limited aquifer for constant terminal conditions has been known since the early 1930's. The solution for the constant terminal conditions for an infinite aquifer was published in 1949.

Optimization of the Idling and Acceleration Characteristics of a Vehicular Gas Turbine by Analog Simulation

1974 ◽  
Author(s):  
C. Klarhoefer
Keyword(s):  
Gas Turbine ◽  
Control Unit ◽  
Torque Converter ◽  
Analog Computer ◽  
Ambient Conditions ◽  
Gas Generator ◽  
Analog Simulation ◽  
Idle Speed ◽  
Power Turbine ◽  
Nozzle Opening

For simulating the performance of a two-shaft regenerative gas turbine with variable nozzles on the power turbine, a mathematical model for the whole system engine-control unit-vehicle was programmed on an analog computer. This paper reports on a study carried out to discover the extent to which the acceleration of the car is influenced by the following parameters: (a) Idle speed of gas generator; (b) Power consumption of auxiliary units; (c) Transmission with a hydrokinetic torque converter; (d) Time constants of temperature gauge and fuel metering system; (e) Variation of nozzle opening during acceleration; (f) Ambient conditions.

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