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American Institute of Electrical Engineers, Part II: Applications and Industry, Transactions of the

Issue 6 • Date Jan. 1961

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Displaying Results 1 - 19 of 19
  • Application of cryogenics to electrical and electronic design

    Page(s): 433 - 438
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    CRYOGENICS is a science concerned with the very-low-temperature environment, extending from a high of 77 K (degrees Kelvin), or ¿196 C (degrees centigrade), where liquid nitrogen (N) boils at standard pressure, down to absolute zero (0 K or ¿273 C). This region has come to be associated with rockets, many of which carry large quantities of liquefied hydrogen (H) and oxygen (O) as propellants. View full abstract»

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  • Model laws of eddy-current couplings for aircraft alternator drives

    Page(s): 438 - 442
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    A description of different types of eddy-current clutches is given. The difficulties encountered in designing these are explained. A method to predict the torque-speed characteristic of eddy-current devices based on dimensional analysis and model theory is developed. Experimental data show the calculations made with the method are sufficiently accurate for engineering purposes. View full abstract»

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  • Precise frequency power generation from an unregulated shaft

    Page(s): 442 - 451
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    A system for generating precise frequency power from an unregulated shaft is described. The system comprises a high-frequency variable-speed generator, a semiconductor frequency changer, an output filter, and a voltage and frequency regulator. The semiconductor frequency changer employs silicon p-n-p-n switches as the power handling components. The operation of a typical frequency changer is described, and an oscillogram is presented which verifies the performance. Also, the ability of the frequency changer to supply a lagging reactive load is illustrated. The generator described is a brushless Secsyn type. The rotor of this machine has no rotating exciting windings and is of tubular steel construction which permits very-high-speed operation. This results in a lightweight system. Voltage regulation is accomplished by controlling both the frequency changer and the excitation of the generator. This improves speed of response. The frequency regulator is open-loop with a frequency transient that is no more than wave distortion. The accuracy of the system frequency is determined entirely by the accuracy of the frequency reference which can be as high as 0.001%. Application of the system to emergency power systems, auxiliary power systems, and secondary power systems is mentioned. View full abstract»

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  • Determination of intermittent duty rating of an aircraft motor by equivalent thermal circuit and a direct analog computer

    Page(s): 451 - 460
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    THE ELECTRIC MOTOR is an important accessory in the functioning of modern aircraft. Motors like all other accessories must be tailored to the job to be done and, because of unknown factors of application, aircraft design, to be successful, cannot tolerate wastefully large and bulky accessories, nor can it tolerate the risk of plane and mission with equipment that is undersized for its task. View full abstract»

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  • Gas discharge lamp fixtures for aircraft navigation lights

    Page(s): 461 - 466
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    ONE of the objectives of an aircraft exterior lighting system is to assist in the avoidance of aircraft collisions. Lights can do this in clear weather by attracting the attention of an observer, and by presenting visual information which will enable the observer to take evasive action. There is considerable lack of agreement as to the fundamental requirements for an exterior lighting system which will provide the highest level of conspicuity. It is generally agreed that no single direction has a monopoly on collision courses. Red flashing anti-collision beacon lights are now being provided to attract the attention of the observer. Red, green, and white navigation lights provide the observer with the information required to determine the position or orientation of the aircraft, and therefore its direction of travel, so that an avoidance maneuver may be executed. View full abstract»

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  • Integral of the error squared as a performance index for automatic control systems

    Page(s): 467 - 471
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    IN 1943, Hall proposed the integral-of-squared-error (ISE) criterion as an indirect measure of the speed of response (to a step input) of servomechanism systems.1 This index of performance was proposed as an analytical function of the servomechanism parameters which would be minimized by adjustment of the system parameters, the relationship between the parameters and the ISE being less complex than that between the parameters and the speed of response itself. As a result of Hall's work the ISE was tabulated as a function of system constants for systems whose error function is of tenth order or less.2,3 View full abstract»

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  • Optimization of multioutput linear time-varying systems subject to multiple or redundant nonstationary inputs

    Page(s): 471 - 475
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    THE OPTIMIZATION of linear systems with single input and output terminals has already been treated in considerable detail. Booton demonstrated that the impulse response of such systems satisfies a modified Wiener-Hopf linear-integral equation.1 The practical solution of such equations was materially enhanced by Shinbrot, who demonstrated that relatively simple closed-form solutions could be obtained for suitable approximations to the associated correlation functions.2,3 View full abstract»

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  • Control programing ¿ Key to the synthesis of efficient digital computer control systems

    Page(s): 475 - 502
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    Dost thou love life? Then do not squander time, for that is the stuff life is made of¿ Remember that time is money. View full abstract»

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  • On the information-handling efficiency of a digital computer program

    Page(s): 502 - 508
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    The use of a stored-program digital computer as an element in a control system raises a number of problems which have not previously been encountered in the control field. This paper is concerned with the effectiveness of the computer program in performing its assigned task (of satisfying the precision and dynamic response requirements of the system) with a computer of minimum capability. The concept of information-handling efficiency is utilized as a measure of program effectiveness and is related to the problem of minimizing the computer cycle times. A procedure is described in detail for developing an optimum program schedule for a multivariable control system. View full abstract»

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  • The concept of in-phase transfer applied to industrial systems serving essential service motors

    Page(s): 508 - 518
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    THE PROBLEM of transferring industrial loads from a preferred source to an emergency source has become more important as an increasing number of electric motors are being used to drive critical loads. The previous practice of having turbines drive these critical loads has, as the trend shows, shifted to replacement of turbines by motors. In those cases it is desirable that the continuity of electrical service should be such that an unscheduled shutdown of this type of load be practically eliminated. View full abstract»

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  • Derivation of economic dispatch equations: A step in the automation of gas transmission

    Page(s): 518 - 523
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    THE NATURAL GAS transmission industry has been an industry of rapid growth. The physical expansion has been paralleled by rapid technological developments and, at the moment, there is considerable interest in computer-controlled systems. There is a general understanding of the form of such systems evidenced by the many articles and publications dealing with the subject. This understanding is based on experience with automatic sequence and feedback control of individual compressors or stations and with supervisory control of several stations from a central point. Relieving the central dispatcher of his routine duties through the use of a computer to collect and process data and make decisions is not difficult conceptually. In this respect, the stage is set for the introduction of computer-controlled systems. View full abstract»

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  • An automatic root locus plotter using an analog computer

    Page(s): 523 - 527
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    THE METHOD of plotting the locus of roots of the characteristic equation of a linear feedback control system has been essentially a manual point-by-point calculation. The basic principles for plotting the root locus were first developed by Evans. The details for analytically calculating some portions of the curves and the procedures for finding points on the curves by a trial-and-error procedure are found in many books in the area of feedback controls. One source for this material is reference 1. It is also possible to calculate points on the root locus by equations developed in reference 2. These equations can be set up on a digital computer, if one is available. View full abstract»

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  • A direct method of compensating linear feedback systems

    Page(s): 527 - 538
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    A NEW METHOD of direct synthesis of a series compensator for a linear feedback control system is presented. The method permits the designer to satisfy simultaneously specifications on the location of the complex closed-loop poles and on steady-state behavior, taking into account constraints on the open-loop pole and zero configurations. View full abstract»

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  • Optimum transmission of continuous signal over a sampled data link

    Page(s): 538 - 542
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    THE PRESENCE of a sampler in a data transmission link necessarily introduces an error because of frequency aliasing, and a problem solved in the present paper is how to minimize the mean-square value of this error by linear filtering before and after sampling. An equation for determining the least-mean-square value of this error is also derived. View full abstract»

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  • A graphical approach to motor time response

    Page(s): 542 - 545
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    IN the application of motors for specific duty cycles, driving an arbitrary time varying load, affected by nonlinear damping and dry friction, the time response is often quite difficult to determine analytically. In this paper a method is presented that yields a quick graphical answer which avoids all the difficulties that appear in the analytical treatment of the problem. View full abstract»

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  • Design of an inductive load for D-C control circuit devices

    Page(s): 546 - 549
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    The term ¿inductive load¿ is often seen in connection with the ratings of contacts. At times an attempt has been made to eliminate some of the ambiguity associated with this term by using a value of circuit ¿time constant¿ or ¿L/R ratio,¿ to specify the type of load which the contacts might be required to interrupt. When there are no iron or eddy currents present in the load inductance, this type of description is sufficient; but when the load consists of iron-core inductances, this type of description is not sufficient to describe the effects of the circuit inductance on circuit interruption. An interesting discussion on this subject can be found in reference 1. This paper will attempt to show why further factors must be considered when iron is present in an inductance, and will propose a method of specifying the characteristics of an inductive load. With the aid of such specifications, an equivalent test load for any type of inductive device might be built with some degree of confidence that the test load-interruption characteristics will be similar to the actual load-interruption characteristics. View full abstract»

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  • Optimum linear filtering of signals prior to sampling

    Page(s): 549 - 555
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    A SOLUTION of the problem of determining a filter for the optimum recovery ¿ In a mean-square sense ¿ Of sampled data has been presented previously.1¿6 Examples for the application of this solution include radar tracking systems and systems where measuring instruments provided values at discrete time-instants. These are cases in which the data are available only in sampled form. However, there are important situations involving sampled data which are not included in this category. The case which is considered here is the one in which a continuous signal, consisting of data and noise, is to be sampled. In such a case, it is shown that the signal should be filtered before sampling. An expression is derived for the optimum ¿prefilter¿ as specified by a mean-square-error criterion, and examples are presented for illustration purposes. View full abstract»

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  • Statistical analysis of amplitude-quantized sampled-data systems

    Page(s): 555 - 568
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    QUANTIZATION, or round-off, occurs whenever physical quantities are represented numerically. The values of measurements may be designated by integers corresponding to their nearest numbers of units. Round-off errors have values between ±1/2 unit, and can be made small by choice of the basic unit. It is apparent, however, that the smaller the size of the unit, the larger will be the numbers required to represent the same physical quantities and the greater will be the difficulty and expense in storing and processing these numbers. Often, a balance has to be struck between accuracy and economy. In order to establish such a balance, it is necessary to have a means of evaluating quantitatively the distortion resulting from rough quantization. The analytical difficulty arises from the inherent nonlinearities of the quantization process. View full abstract»

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  • Applications and industry index for 1960

    Page(s): 569 - 575
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    Freely Available from IEEE

Aims & Scope

This Transaction ceased production in 1963. The current retitled publication is IEEE Transactions on Industry Applications.

Full Aims & Scope