Electronic Analog Computer Research Articles

フーリエ解析機による波浪・動揺の解析について(日本航海学会第24回講演会)

In their studies of ship's oscillations in a seaway, in order to analyse a large amount of data concernig ship's oscillations automatically in a short time, the authors used a Fourier Analyser, a kind of electronic analog computer, which was designed so work as in M.J. Tucker and T.B. Whiteley's way. A view of the whole apparatus and diagram illustrating the principle of the Fourier Analyser are shown in Photo.1 and Fig.2 respectively. By this apparatus, the spectra of ship's oscillations and wave heights were calculated on some examples which were discussed in the former paper by one of the authors. Results of the calculation are shown in Figs.8, 9, 10 and 11.

Pacit, a small-budget expandible precision analog computer

With the initiation of nuclear reactor design and construction in Finland, a general purpose precision electronic analog computer becomes a valuable development and training tool. The design and construction of the nucleus of an analog facility on a small equipment budget is described. The unit-package design and other provisions make this 12 amplifier computer readily expandible to a 24 amplifier machine with equivalent expandibility as well in its non-linear simulation components. A detailed enumeration of the design criteria used to guide the construction of PACIT is presented. A general description of the console is accompanied by details of several control, safety, and flexibility features. Recommendations concerning operating techniques and future expansion components are made.

A New, Solid-State, Nonlinear Analog Component

Since the inception of the electronic analog computer as a useful engineering tool, the need for practical methods of solving nonlinear problems has steadily increased. This paper describes a passive, nonlinear device which, when used with operational amplifiers, provides the means for obtaining a large class of functions. These are obtained to a degree of accuracy and reliability not previously possible with a simple, economical device. A basic varistor squaring unit is described. The unit has been compensated for the various types of error inherent in the varistor itself, and is capable of providing approximately fifteen of the most basic and commonly used nonlinear functions.

The Numbers Game

Electronic Computers Principles and Applications. By T. E. Ivall. Second edition. Pp. viii + 263 (32 plates). (London: Iliffe and Sons, Ltd.; New York: Philosophical Library, 1960.) 25s. net. Computer Engineering Edited by S. A. Lebedev. Translated from the Russian by Jane Stuart. Translation edited by J. P. Cleave and F. A. Sowan. Pp. vii + 184. (London and New York: Pergamon Press, 1960.) 63s. net. Analogue and Digital Computers Consulting Editor: Dr. M. G. Say. Advisory Editors: A. C. D. Haley and W. E. Scott. Pp. viii + 308 + 12 plates. (London: George Newnes, Ltd., 1960.) 50s. net. Introduction to Electronic Analog Computers By Prof. John N. Warfield. (London: Prentice-Hall Electrical Engineering Series.) Pp. ix + 175. (London: Prentice-Hall International, Inc., 1959.) 30s.

Diffusion of oxygen into a film of whole blood.

In the study of artificial blood oxygenation, the mechanism of oxygen diffusion and absorption in a blood film is of particular interest. An equation was derived for the diffusion of oxygen into whole blood films that are thick compared to the red cell size. The equation, which was solved on an electronic analogue computer, showed that simple expressions for an advancing interface of oxygenated blood are good approximations. An equation for a blood film bounded by a semipermeable membrane was also derived. An experiment was conducted to confirm the advancing interface theory. In a second experiment, the diffusivity of oxygen in whole blood was found to be approximately 1.3 (10–5) cm2/sec. When using highly permeable membranes, such as silicone rubber, in a blood oxygenator, the relative permeabilities of a blood film and the membrane are such that in many cases the resistance of the blood film is the controlling factor. Submitted on October 5, 1959

A Computer for the Automatic Processing of Fiber, Yarn, and Fabric Stress-Strain Data

During single-fiber tensile tests, major transitions in rheological behavior occur at the Young's modulus and yield-point regions. In the former region there is a transition from uncrimping (nonlinear spring) to approximate spring-like or Hookean behavior, and then to viscoelastic or plastic flow. In the latter region the transition is from Hookean extension to maximum plastic flow. The center of each transition region provides the basis of a new and better definition of the Young's modulus and yield points since these points are directly determined by the molecular-flow properties of the fiber. The uncrimping point is also defined on the basis that it is at or near the center of a transition from pure lielical spring to nonlinear spring and then to approximate Hookean behavior. An advantage of defining the parameters in this way is that they may be located through the use of the second and third stress derivatives as obtained by electronic analog computer techniques. Such techniques involve the use of inexpensive standard laboratory-type computer components. Thirty percent stretch and the ultimate tensile points may also be obtained. Voltage analogs of stress, strain, slope, and energy are stored in the computer's memory section at any of these points, or at any other selected stress or strain points. Twenty-one or more parameters may be computed and stored. Adaptations to yarn and fabric tensile tests and a modification to automatically dial in initial fiber length and reverse elongation are also descrihed. Through the use of analog-to-digital converters, these data may be automatically punched on cards or tape for storage or further analysis on a digital computer.

A stochastic method of solving partial differential equations using an electronic analogue computer

A stochastic method of solving partial differential equations using an electronic analogue computer

Computer Training Equipment — an approach to the economic and educational problems of computer teaching

THE STEADY increase in the number of electronic digital and analogue computers used in industry for scientific and commercial work has stimulated a demand for education in the computer field to be provided by colleges of technology.

A Precision Amplitude-Distribution Amplifier

A new electronic slicer circuit produces output pulses whenever a random input voltage x(t) is between two slicing levels X - Δx/2 and X+Δx/2. The slicer pulses gate a counter to produce a direct digital readout count equal to the estimated first-order probability density of the input signal. The system was designed for random process studies with conventional electronic analog computers and has compatible accuracy.

クロマグロと沿岸魚種との相互関係について

As to theoretical models of prey-predator relationships among fishes, VOLTERRA's differential equations are well-known. Nevertheless, there are a great deal of criticism that those equations cannot stand for real circumstances of community of fishes or animals. But as the equations are convenient to examine the community problems of fishes, discussions about the equations are now often presented. This report is a trial to prove whether VOLTERRA's equations are applicable to the predatory relationships between bluefin tuna, a predator, and coastal fishes in the southern waters of Japan. An electronic analogue computer was employed in solving the equation which is a kind of non-linear differential equations. The following are the results obtained. First, relationships between bluefin tuna and common squid in the waters for the years 1951 to 1955 have been examined. In Fig. 2 the broken line, generated by a function fitter of the analogue computer, represents the actual variations in the stock of common squid for the years 1951 to 1955, and the other curves stand for the theoretical variations in the bluefin tuna computed by the analogue computer for various values of a parameter of VOLTERRA's equation. The graphical form in the middle of theoretical curves is similar to an actual variation of bluefin tuna. Therefore, as far as those years are concerned, it seems that these two fishes are in prey-predator relationships fitted to VOLTERRA's equation. In the second place, for the years 1951 to 1956 instead of to 1955, it was found impossible to make a theoretical graphical form similar to actual variations of bluefin tuna. But when total catch of coastal fishes is considered instead of common squid alone, it is possible to find out the predatory relationships between bluefin tuna and the sum of coastal fishes for the year 1951 to 1956, as shown in Fig. 4. From these results it is concluded that bluefin tuna and coastal fishes including common squid are in predatory relationships in the southern waters of Japan.

Respiratory control of heart rate: laws derived from analog computer simulation.

The application of dynamic systems analysis, essential for the design of controlled missiles and of man-made automatic control systems of all kinds, to the control systems within the human organism, is beginning to bear fruit in medical science. These organic control systems, which are part of the living process, generally far surpass any man-made systems in subtlety and ingenuity. Their exploration in terms of feedback control theory is highly instructive both to the medical scientist and to the control engineer, since these systems generally display a quality and perfection of control design several orders of magnitude greater than the human mind can now conceive. Some aspects of the control of the human heart rate are presented here. Normal and irregular respiration widely changes the rate of the heart from beat to beat. The mathematical laws describing this behavior were derived from analog computer simulation. On the analog computer a mathematical model of the dynamics of the processes involved was created. This was achieved through the use of dynamic data obtained from experiments designed by the help of control theory. These mathematical laws are useful for understanding the operation of the system concerned, and especially valuable for predicting the existence of hitherto unknown structural and organizational relationships, which can be confirmed experimentally. The electronic analog computer, being fed information about the respiration of the subject, in the form of an electric signal proportional to chest circumference, is able to calculate the timing of the heart beat from beat to beat.

The use of silicon diodes in d.c. modulators and their applications to drift correctors for computing amplifiers

The basic computing element of an electronic analogue computer is the high-gain d.c. amplifier, but in order to overcome its inherent drift some form of auxiliary drift-correcting amplifier is frequently used.The paper describes a silicon diode modulator for use in such drift correctors, and shows that the zero stability which can be achieved is comparable with that given by the conventional relay modulator. It is also shown that the use of the diode circuit results in a number of improvements in the overall drift-corrector performance, such as a higher frequency response and practically unlimited life; the design of such a drift corrector for use with a given d.c. amplifier is described in detail and the resulting performance is assessed.

Use of an electronic analogue computer with resistance network analogues

Use of an electronic analogue computer with resistance network analogues

Reply to "Use of an electronic analogue computer with resistance network analogues"

Reply to "Use of an electronic analogue computer with resistance network analogues"

Analog computer analysis of flow characteristics and volume of the pulmonary vascular bed.

Radioisotope dilution data were obtained from the pulmonary artery and pulmonary vein of catheterized dogs and an analysis for pulmonary transfer characteristics was performed with an electronic analog computer. The analog for these studies consisted of a cascade of linear delay units arranged so that both transport delay and dispersion could be independently varied. This technic makes it possible to characterize the pulmonary vascular bed without making any assumptions as to its nature. The results indicate that the dominant response of the lung is not that of a single mixing pool as suggested by Newman and others, but rather is more analogous to a laminar flow system. In addition it has been shown that an exponential extrapolation of the downslopes of the indicator dilution curves to calculate pulmonary blood volume results in a measurable error.

Generalized Integration on the Analog Computer

One of the major limitations of the electronic analog computer is its inability to perform directly an integration with respect to a dependent variable. This paper reviews the usual methods of overcoming this limitation, describes the results on an attempt to use Pade time-delay units in generalized integration, and presents the development of a new analog integrator based on a simple numerical integration formula. The integrator can be instrumented using standard analog computer components. The performance of the device is illustrated with several examples.

Optimization by Random Search on the Analog Computer

One method of searching a system for optimum operating conditions is to evaluate system performance for many randomly-chosen combinations of the independent parameters. This paper explains the use of standard electronic analog computer equipment to accomplish such a search of a mathematical model quickly and economically. Gaussian noise sources generate values of the independent parameters and sample-hold circuits hold those values which give the best value of the optimization criterion. An application of the method to a production allocation problem is mentioned.

Distributed Parameter Vibration with Structural Damping and Noise Excitation

A method is described for the electronic analog computer that will permit the determination of the vibration amplitude responses of a distributed system with structural damping to a random-noise excitation such as might be experienced by a missile structure accelerated by a jet propulsion system. There is general agreement among the investigators in the literature that structural damping is both frequency independent and amplitude dependent. Simulation of the structure by a method of normal modes permits the introduction of a discrete equivalent viscous-damping coefficient for each mode frequency, thereby effecting the frequency-independent characteristic of structural damping.

THE ESTIMATION OE THE TRANSFER FUNCTION OF A HUMAN OPERATOR BY A CORRELATION METHOD OF ANALYSIS

Abstract This paper records an experiment to determine the transfer-function of a human operator, when he is acting as an element in a closed-loop control-system, by a mothod of analysis which is based on correlation functions. The theoretical analysis shows that under certain conditions the transfer-function of the operator can be defined by an integral equation that relates a, cross-correlation function of his response to an observed ‘ error ’, to the auto-correlation function of tluit ‘ error ’. It is shown how this integral equation can be solved approximately by a technique which uses an electronic analogue-computer. In this instance such a computer has been used to determine the parameters that will ‘ best fit ’ an assumed form of transfer-function to the recorded data.

A MECHANICAL ANALOGUE COMPUTER

The Bush Differential Analyser. This machine was the forerunner of the electronic analogue computer. The first engineering model was constructed in 1931 at Massachusetts Institute of Technology. Dr Hartree first tried out at Manchester a small scale model, largely made of Meccano parts, and was surprised at the accuracy obtained. Dr Bush's machine was eventually fitted with a number of electronic controls, and so foreshadowed present day electronic analogue computers.