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Electrical Engineers, Proceedings of the Institution of

Issue 1 • Date January 1976

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Displaying Results 1 - 20 of 20
  • Inaugural address. `Only connect¿

    Publication Year: 1976
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (3391 KB)  

    The title suggests both the benefits and the problems of communication and the relationships between communication systems and those who use them. The theme is the role that electrical engineering can play in improving communications and in the optimisation of relations between equipment and people. The profession has made major contributions to increasing man's abilities to communicate. Its technologies have given us a variety of methods of communication for differing purposes and will continue to offer increasing speed and greater quantity. In the future these should not be the only objectives. The ultimate object of communications is to connect people. The aim must be for systems matched to users which meet needs, at desired times, between places of people's choice and at a cost and use of resources which can be afforded. A number of recent advances are described, and ways suggested by which various modes of communication, and combinations of them, could offer increasing scope for a variety of versatile facilities in the future. Development of communication technology will and should continue, and advances will change ways of life. The challenge is to use them in the right way; to use them for personal development rather than becoming passive terminals; and to advance understanding of the possibilities, the dangers of misuse, and the way they can be used for the advancement of man. View full abstract»

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  • IEE Electronics Division: Chairman's address. Electronics and the aeroplane

    Publication Year: 1976 , Page(s): 13 - 15
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    The paper traces the development of electronics applications to aviation (avionics). The rapid development of electronic equipment and systems is discussed, and the paper points out the mutual dependence of air frame and equipment in aerospace projects. View full abstract»

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  • Experimental airborne radar transmitter

    Publication Year: 1976 , Page(s): 16 - 20
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (930 KB)  

    The design, manufacture and commissioning of an airborne radar transmitter amplifier is described. The microwave valve employed is a crossed-field amplifier (c.f.a.), cathode modulated by a hard-valve shunt modulator. The peak output power is 15 kW, and pulse lengths up to 5 ¿s may be used. The e.h.t. supply is derived from a high frequency transistor invertor stabilised by a feedback loop. View full abstract»

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  • Capacitance-change transducer applied to rotating vane anemometry and tachometry

    Publication Year: 1976 , Page(s): 21 - 25
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    Electrical transducing methods for use in rotating-vane anemometry and tachometry are discussed and the advantages to be gained from a capacitance-change pickoff are outlined. Both a theoretical and practical analysis for the capacitance variation in such systems is given, leading to the conclusion that the resulting change, when converted into a voltage-time signal is ideally suited to cable and telemetry transmission. A simple transducingcircuit technique is then presented with measured results indicating that changes of less than 0.01 pF can readily be resolved. In addition, the circuit performance with high residual-capacitance values is investigated, the results of which have led to the development of an insertion-type flowmeter. The paper is concluded by illustrating the application of the techniques in a respiratory-flow transducer. View full abstract»

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  • On the error-correcting capability of optimum linear block codes

    Publication Year: 1976 , Page(s): 26 - 31
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    The performance of optimum linear block codes has been examined by computer simluation, and the error distribution at the decoder output, the block-error probability and the bit-error probability have been determined for the codes when they are used on a binary symmetric channel with random errors. A table showing the distribution of errors in the decoder output is presented, and it is shown how the table can be used to determine exact values for the bit-error probability and the block-error probability. The exact values of bit-error probability computed from the table are compared with values obtained using a known theoretical approximation to the bit-error probability, and some conclusions are drawn as to the general usefulness of the theoretical approximation. Also, block-error probabilities are computed from the information presented in the table and these values are compared with the estimates of block-error probability obtained from minimumdistance considerations. View full abstract»

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  • Nonlinear equalisers using modulo arithmetic

    Publication Year: 1976 , Page(s): 32 - 38
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (860 KB)  

    The recent published literature contains a description of a data-transmission system in which the data signal at the transmitter is fed through a channel equaliser that includes a device for holding the transmitted signal within a given range of values. The paper presents a theoretical analysis of the system, together with the results of computer simulation tests, and proposes a simple modification to the equaliser that maximises the tolerance of the data-transmission system to additive white Gaussian noise. It is shown that the original and modified equalisers are equivalent, both in their basic methods of operation and in their tolerances to noise, to the corresponding conventional nonlinear equalisers, used at the receiver. Finally, a simple error detector is described which operates on the received signal, with no need for any redundant data, and which gives extremely powerful protection against errors when used with the original nonlinear equaliser at the transmitter. View full abstract»

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  • Distortion performance of the parametric upconvertor as a communications receiver front end

    Publication Year: 1976 , Page(s): 39 - 43
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (570 KB)  

    An analysis is developed for the prediction of intermodulation distortion effects in abrupt-junction current pumped varactor frequency convertors optimised to satisfy the requirements of communications-receiver front-end performance. The technique is extended to the prediction of gain compression effects, and is applied to a practical circuit. Excellent agreement with predictions is demonstrated for intermodulation performance; and a useful indication of gain compression is shown. View full abstract»

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  • IEE Power Division: Chairman's address. Consulting engineering for power projects

    Publication Year: 1976 , Page(s): 45 - 50
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    The different roles of manufacturers, supply authorities and consultants in the British electrical-supply industry date from the very start of electrical power engineering at the end of the 19th century. The paper traces the role of the consulting-engineering profession in the development of the home supply industry through the men who founded practices at that time leading to the development of today's British consulting engineering firms which serve the power industry of the world. The development of these firms is shown throughout the years to have depended on engineering, economic and political factors. Consulting-engineering work is illustrated with reference to two projects: an unusual power station project in Mexico and the topical Hong Kong mass-transit system. The changing problems of the consulting-engineering profession are considered in the light of current economic pressures, energy patterns and the increase of nationalism overseas, and it is shown why the services of British consulting engineers have never been in greater demand throughout the world than at the present time. View full abstract»

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  • Design, testing and construction of the 500 kV overhead lines for the El Chocon-Buenos Aires transmission system

    Publication Year: 1976 , Page(s): 51 - 59
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    The paper describes, briefly, the background to the El Chocon 500 kV transmission system, indicating the size and location of the generating plant together with the atmospheric and natural conditions prevailing along the line route to the greater Buenos Aires load centre, some 1040 km to the north east of the generating sources. The electrical requirements of the two physically independent but parallel overhead lines are discussed in terms of the required phase-conductor arrangement. The optimum economic conductor size is shown to co-ordinate with the requirements of radio interference and line reactance. The expected fault performance of the lines is examined, and the earthwire and tower-foot earthing requirements to give satisfactory lightning performance are outlined. The mechanical design of fittings, including joints, clamps, spacers and dampers is described. A section is devoted to the electrical-performance requirements of the insulation, mainly in terms of the required switchingsurge performance and radio-interference characteristics. The tests necessary to prove the performance of the `V¿ string insulators in satisfying the above requirements are described. The type of suspension tower finally chosen, of guyed construction, is justified, together with a description of tower foundations, guy anchors and tower tests. The paper concludes with a discussion of tower-assembly and erection techniques and the problems relating to conductor stringing. View full abstract»

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  • Assessment of the influence of soil thermal resistivity on the ratings of distribution cables

    Publication Year: 1976 , Page(s): 60 - 72
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1653 KB)  

    The paper summarises the findings of an extensive field investigation into the behaviour of soils affecting operation of buried power cables. Statistical treatment of the large volume of results available leads to the establishment of thermal-resistivity values for defined groups of soils and the main types of load encountered in practice. View full abstract»

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  • Discussion on ¿Proposals for installation of single-core cables¿

    Publication Year: 1976 , Page(s): 73 - 75
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  • Development of a 300 kW 3000 rev/min d.c. machine using thyristor-assisted commutation

    Publication Year: 1976 , Page(s): 76 - 80
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (907 KB)  

    The principle of thyristor-assisted commutation was easily demonstrated on small laboratory-type machines, but the commercial significance of the concept could only be investigated by constructing a machine of a size where commutation would normally be a problem. A 300 kW, 3000 rev/min version was built and the performance of this prototype is described. In particular, it is explained how the problematic sliding-contact performance of this type of machine was satisfactorily achieved using (eventually) only commutators and brushgear of conventional construction. Companion papers describe the commutating-time calculations and the terminal characteristics of the machine. View full abstract»

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  • Commutating time calculations for machines using thyristor-assisted commutation

    Publication Year: 1976 , Page(s): 81 - 84
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    A calculation of the commutating time for machines using thyristor-assisted commutation is as important to these machines as the calculation of current-reversal curves for conventional d.c. machines. New factors enter into the determination of the inductance of a commutating coil, particularly an inductance component attributable to a main-pole-axis flux change. Different procedures also apply to the calculation of armaturereaction m.m.f. and interpole-induced voltage. A logical design procedure is described and applied to a typical machine. The development and the terminal characteristics of such a machine are described in companion papers. View full abstract»

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  • Terminal characteristics of machines with thyristor-assisted commutation

    Publication Year: 1976 , Page(s): 85 - 88
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (567 KB)  

    Machines with thyristor-assisted commutation(t.a.c.) have some unusual output characteristics. The small number of commutator sections and the consequently wide interpoles cause voltage and torque pulsations of appreciable amplitude, although the current ripple is usually small. A change in the commutating time with current causes an effective brush swing, resulting in an interpole-generated component of the armature voltage that is current dependent, and also changing the main-pole flux. This current-dependent brush-swing is very advantageous in lapwound machines, as it automatically acts to compensate unbalance of the generated voltages to an extent that makes equalising connections unnecessary. The development of a t.a.c. machine and the commutating-time calculations are described in companion papers. View full abstract»

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  • Optimum goodness criterion for linear-induction-motor design

    Publication Year: 1976 , Page(s): 89 - 92
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Linear induction motors (l.i.ms) have many possible applications, ranging from low-speed cranes to high-speed ground-vehicle propulsion. However, in average and high-speed l.i.ms, the end effects cause considerable deterioration in the performance in low-slip regions. The paper introduces the concept of realistic goodness factor GR, which takes into account by appropriate coefficients the airgap leakage, secondary sheet skin effect and transverse edge effects. Approximations involved in obtaining GR are discussed and essentially a one-dimensional analysis is used. It is shown that the end-effect influence can be expressed as a function of GR, slip and the number of poles. An optimum goodness-factor criterion Go to aid an optimum l.i.m. design is proposed. It is demonstrated that Go can be achieved in practice, and leads to a good-performance, low-weight l.i.m. Numerical results based on a full-size existing l.i.m. test vehicle are given. View full abstract»

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  • Simulation of power-system fault currents and voltages for protective-equipment testing

    Publication Year: 1976
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  • IEE Control & Automation Division: Chairman's address. Some developments in computer-aided information services for the blind

    Publication Year: 1976 , Page(s): 93 - 97
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (647 KB)  

    The paper reviews the needs of the blind community for printed material, and surveys current developments in the applications of automation to increase the availability of Braille. The problems of automatic translation of English text to Braille are considered. Some possible systems for giving a greatly improved access to Braille are surveyed, and an automated system for map and diagram production is reviewed. The future provision of information services for the blind, using special systems or existing systems with special terminals, is discussed. The technical problems are not trivial, but collaborative ventures, with international cooperation, could offer solutions in a relatively short time scale. View full abstract»

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  • Design of multivariable digital control systems using the sequential return difference method

    Publication Year: 1976
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (318 KB)  

    The sequential return difference method is applied to the design of a digital controller for a multivariable digital system. Although the open loop system is unstable, it is shown that a controller which provides good transient behaviour and low interaction may be designed by the appropriate sequence of single-loop, digital, root-locus designs. View full abstract»

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  • IEE Science Education & Management Division: Chairman's address. The professional engineer in the 1990s

    Publication Year: 1976 , Page(s): 101 - 106
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    The paper deals briefly with the history of engineering and its recognition as a profession. The growth of professional institutions is traced and their contribution to the education, training and qualification of engineers is explained, with reference to the Council of Engineering Institutions. After a review of the present situation, the roles of professional chartered and technician engineers are considered, with special emphasis on trends and possibilities in the development of engineering, especially electrical engineering, in the final decade of the 20th century. A significant problem is likely to be a decline in the output of engineering graduates; some reasons for this and some possible solutions are suggested in the paper. View full abstract»

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  • Sparking potentials and ionisation coefficients in SF6

    Publication Year: 1976 , Page(s): 107 - 108
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (374 KB)  

    Steady-state ionisation currents under uniform field conditions have been measured in SF6 over the range 110 ¿E/p¿1000V cm¿1torr¿1 with gas pressures varying from 1 to 10 torr, at 20°C. Sparking potentials Vs were also measured for a range 1¿pd¿20 torr-cm. Townsend's primary ionisation (¿/p) and electron-attachment (¿/p) coefficients were found to depend on E/p only. The values of secondary-ionisation coefficient (¿) were also determined over the range 140¿E/p¿600 V cm¿1 torr¿1. Measurements of Vs of SF6 have shown that the deviations from Paschen's law rise up to ±3.5% at values of pd near the Paschen minimum. 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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