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Electrical Engineers, Proceedings of the Institution of

Issue 5 • Date May 1973

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Displaying Results 1 - 25 of 25
  • Spectral-energy dispersal in digital communication-satellite systems

    Publication Year: 1973 , Page(s): 529 - 532
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (458 KB)  

    Communication-satellite systems employing analogue or digital modulation techniques generally require some means of artificially dispersing their spectra to reduce interference to other services sharing the same frequency bands. In digital systems, the dispersal can be obtained by the modulo-2 addition of a pseudorandom sequence to the information signal. Expressions have been derived for the maximum spectral power in the signals of time-division multiple-access systems employing p.s.k. modulation and using this means of dispersal. The spectral density due to the preambles in such signals is also determined. An example of the practical application of the expressions is given. View full abstract»

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  • Waiting time in common-control queuing system

    Publication Year: 1973 , Page(s): 533 - 538
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (594 KB)  

    The paper presents a detailed study of a general combined delay and loss common-control queuing system with a Poisson input, first-come-first-served queue discipline and negative exponential distribution for the operating times of the common control and the service times of the servers. In terms of the system state probabilities, a new approach is developed for the investigation of the waiting-time distribution in the system. This approach makes use of the stochastic-transition signal-flowgraph representation. Formulas for calculating the loss probability and waiting probability are also given. View full abstract»

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  • Studies on waveguide-fed slot antenna

    Publication Year: 1973 , Page(s): 539 - 540
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (235 KB)  

    The paper presents investigations of the effect of stored energy inside a waveguide, near a displaced narrow longitudinal slot, on the immittance properties of the radiating slot. It is shown that internal stored energy accounts for the discrepancy between the theoretical and experimental results of the immittance characteristics observed in earlier studies. The effect of stored energy is to contribute an additional reactive term in the expression for the immittance of the slot. By the addition of this extra reactive term to the theoretical expression for the immittance, it has been possible to predict the point of resonance with better accuracy. Further, an expression is derived for the immittance presented by a slot to the transmission-line representation of the waveguide, as a function of slot length, displacement etc. by the application of the principle of duality to the dipole antenna. View full abstract»

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  • Concept of phase centre of an array applied to elevation-angle measurements

    Publication Year: 1973 , Page(s): 541 - 543
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    A linear receiving array can be regarded as possessing a phase centre the position of which varies with the direction of arrival of the signal. This concept has proved useful in a study of the effects of imperfect ground reflection on elevation-angle measurements made with the wavefront-analysis technique. A distinction is drawn between ground-interference minima and free-space nulls. View full abstract»

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  • Thin monopole antenna: finite-size belt-generator representation of coaxial-line excitation

    Publication Year: 1973 , Page(s): 544 - 550
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (827 KB)  

    The real system of a vertical monopole, obtained as a simple protrusion of the inner conductor of a coaxial line through the ground plane, is approximated by a monopole base driven by a finite-size belt generator. A simple formula is derived for determining the size of the belt generator so that it is equivalent to the coaxial-line excitation. The integral equation for current obtained with the finite-size belt generator is similar to the well known equation for the delta-function generator. However, the new equation has an integrable solution, convergent at all points. In particular, the monopole admittance obtained from the modified integral equation closely approaches, in the limit, the apparent admittance of the monopole, as measured by reflection measurements on the coaxial line and referred to the ground plane. View full abstract»

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  • Sequential-circuit characterisation and synthesis using a `transition-equation¿ approach

    Publication Year: 1973 , Page(s): 551 - 556
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (623 KB)  

    The characteristics of combinational and sequential circuits or networks can be expressed in `transition-equation¿ form. Transition characteristic equations carry complete information on the behaviour of the circuit, and are readily derived for any circuit or from any reasonable circuit data sheet. Synchronous, clock and asynchronous inputs can be shown, and also the nature of the clock activation, where appropriate. Propagation delays may also be manipulated with the characteristic expressions. Network characteristics can also be expressed in terms of desired transitions from one state to another, and this leads to straightforward synthesis procedures when circuit characteristics are in transition-equation form. Analysis is equally straightforward. The paper briefly introduces transition characteristic equations by way of J-K flip-flops and NAND gates, and then uses a simple example to illustrate the approach to synthesis. It is clearly shown that the transition equations allow for several different approaches to be taken to the same problem. Hazards due to propagation delays are also revealed, which is particularly helpful, for example, when dealing with `ripple-through¿ arrays. View full abstract»

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  • New active-RC-network realisation for nth-order transfer functions. Signal-flowgraph approach

    Publication Year: 1973 , Page(s): 557 - 559
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (239 KB)  

    A general synthesis method is given for the realisation of nth-order transfer functions by active RC networks containing n unity-gain amplifiers, one differential-input operational amplifier and a minimum number of capacitors. View full abstract»

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  • Erratum: Computer technique for solving 3-dimensional electron-optics and capacitance problems

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (102 KB)  
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  • Erratum: New definitions for loudness ratings

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (102 KB)  
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  • Erratum: Precision hardware circular-arc generation for computer graphic-display systems using line-segment data

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (102 KB)  
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  • Overhead-line parameters for circuit-breaker application

    Publication Year: 1973 , Page(s): 561 - 573
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1365 KB)  

    The paper presents the results of a comprehensive series of measurements and calculations by a collaborative committee aimed at determining values of overhead-line parameters (particularly for lines 1¿8 km long), significant in circuit-breaker application. Line models used in the calculations are discussed, as are refinements made to the models as the work progressed to give a final accuracy of calculation within ±5%. Measurement techniques are described, and the results of surge impedance and 50 Hz inductance and resistance measurements presented. Typical values calculated for the CEGB standard 275 kV and 400 kV lines are given, together with the effect of varying parameters such as frequency, line height and earth resistivity. A particular study was made of the effect of high tower-footing resistance, which was found to increase the 50 Hz inductance per unit length for the shorter line lengths. High footing resistance of the sending-end tower also increases surge impedance, but this is of no importance in practice. From a circuit-breaker viewpoint, the effect of subconductors touching due to attraction under short circuit is shown to be significant, since it increases the rate of rise of transient recovery voltage. View full abstract»

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  • Optimisation of economic dispatch through quadratic and linear programming

    Publication Year: 1973 , Page(s): 574 - 580
    Cited by:  Papers (17)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (915 KB)  

    Mathematical programming offers attractive advantages as an optimising technique. Unfortunately, the optimisation of economic dispatch in power systems is a nonlinear problem, and so it is, in principle, beyond the reach of mathematical programming. In the paper, this difficulty is resolved by the derivation of linear constraints through the system sensitivity relations and by the use of a 2nd-order approximation to the power-generation-cost function. Quadratic programming is employed to solve the problem, and, with only one application of the algorithm, the results are comparable to those obtained from gradient techniques. The use of quadratic programming and the change of type of control variables during optimisation obviate the need for penalty functions. The computing times taken by the algorithm when it is applied to test systems are encouragingly short. Security constraints can be easily incorporated, and, if required, the minimum-reactive-power problem can be solved. A solution of the minimum-loss problem with linear programming is also illustrated. View full abstract»

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  • Discussion on ¿Remote measurement of phase angle¿

    Publication Year: 1973 , Page(s): 581 - 582
    Save to Project icon | PDF file iconPDF (387 KB)  
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  • Discussion on ¿Some aspects of effects of longitudinal and normal stress on power loss and flux distribution within a transformer core¿

    Publication Year: 1973 , Page(s): 583 - 584
    Save to Project icon | PDF file iconPDF (331 KB)  
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  • Design of low-voltage distribution networks. Interactive computer method based on the calculus of variations

    Publication Year: 1973 , Page(s): 585 - 592
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1427 KB)  

    UK electricity boards spend a significant proportion of their capital expenditure on low-voltage distribution systems. Because of the relatively low equipment cost, this leads to a large volume of design work. At present, most of this work is done by hand. The paper describes a method that has been developed to assist engineers in the design of these networks. The method is based on an interactive use of a computer program that derives network configurations, automatically, from single load-flow computations. The kernel of the method is a route-finding algorithm whose theoretical basis is derived from the calculus of variations. The application of the method to the design of networks supplying housing estates, including the problem of evaluating alternative sites for single or multisubstations feeding these networks, is described. Results are presented for practical design studies based on a 500-house estate. View full abstract»

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  • Reduction of cable-joint temperatures by oscillation of oil in the conductor duct a theoretical study

    Publication Year: 1973 , Page(s): 593 - 594
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (298 KB)  

    The effect of oil oscillation in the conductor duct on the temperature distribution in a low-pressure oil-filled cable-and-joint system has been studied by means of a thermal analogue of the system and a digital computer. It is seen that, for a 400 kV cable and joint with integral or sheath cooling, a 50% reduction in the conductor-temperature differential between the joint centre and the remote cable is achieved with oil flows of the order of 10¿5 m3/s and an oscillation period of 20 min. View full abstract»

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  • Lightning-surge distribution in h.v. d.c. convertors

    Publication Year: 1973 , Page(s): 595 - 600
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (678 KB)  

    A complete model of a typical h.v.d.c. converter station suitable for fast transient studies is used to investigate the lightning-surge distribution within the convertor plant. The model is also used to assess the effect of the surge capacitor on the incident wave and the influence of the d.c.-reactor size and the lightning-surge characteristics on the surge transfer to the convertor side. View full abstract»

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  • Erratum: Control by digital computer of multiterminal h.v. d.c. system under fault conditions

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (89 KB)  
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  • Discussion on ¿Behaviour of h.v. d.c. links under unbalanced-a.c.-fault conditions¿ and ¿Control by digital computer of multiterminal h.v. d.c. system under fault conditions¿

    Publication Year: 1973 , Page(s): 601 - 603
    Save to Project icon | PDF file iconPDF (561 KB)  
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  • Discussion on ¿Supply to arc furnaces: measurement and prediction of supply-voltage fluctuation¿

    Publication Year: 1973 , Page(s): 603 - 607
    Save to Project icon | PDF file iconPDF (947 KB)  
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  • Efficient multiple solutions for changes in a network using sparsity techniques

    Publication Year: 1973 , Page(s): 607 - 608
    Save to Project icon | PDF file iconPDF (284 KB)  
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  • Electric-field distribution around an isolated stranded conductor

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (164 KB)  
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  • Reduced-gradient method for economic dispatch

    Publication Year: 1973 , Page(s): 608 - 610
    Cited by:  Papers (3)
    Save to Project icon | PDF file iconPDF (467 KB)  
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  • Polish developments in inductance coils for lightning protection of power stations and substations

    Publication Year: 1973 , Page(s): 610 - 612
    Save to Project icon | PDF file iconPDF (383 KB)  
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  • Effects of flexibility on a momentum-stabilised communication-satellite attitude-control system

    Publication Year: 1973 , Page(s): 613 - 619
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (811 KB)  

    Transfer functions are derived for the coupled roll-yaw-axes control system of a momentum-stabilised satellite. First-mode approximation to the flexural response of movable solar paddles is included in the dynamic equations. The performance of the control system for varying degrees of flexibility is studied using root-locus techniques. The presence of a single flexural mode in the system transfer functions causes an additional pole-zero pair to appear on, or just to the left of, the imaginary axis in the root-locus diagrams. Instability, recognised by root-loci crossing into the right half s plane does not occur. However, flexible modes could be excited by disturbing forces, and, depending on the amplitude of the ensuing motions, would seriously degrade the attitude performance of the satellite. View full abstract»

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Aims & Scope

The Proceedings of the Institution of Electrical Engineers was published by the IET between 1963 and 1979.

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