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Volume 125
Issue 11R
Proceedings of the Institution of Electrical Engineers
Volume 125, Issue 11R, November 1978
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Volume 126 (1979)
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Volume 125 (1978)
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Volume 124 (1977)
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Volume 123 (1976)
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Volume 122 (1975)
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Volume 121 (1974)
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Volume 120 (1973)
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Volume 119 (1972)
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Volume 113 (1966)
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Volume 112 (1965)
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Volume 111 (1964)
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Volume 125, Issue 11R
November 1978
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- Author(s): G.F. Weston
- Source: Proceedings of the Institution of Electrical Engineers, Volume 125, Issue 11R, p. 1077 –1099
- DOI: 10.1049/piee.1978.0245
- Type: Article
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(23)
Alphanumeric displays are playing an increasing role in electronic equipment. Two main applicational areas can be defined: that requiring digital output of up to 16 numerals and that requiring full alphanumeric output of at least 200 characters. For digital output, there are several technologies offering 7-bar displays, the major contenders for the market being light-emitting-diode (l.e.d.), gas-discharge and liquid-crystal displays. Others are vacuum-fluorescent, electroluminescent and incandescent filaments. Above 200 characters, the technologies are more limited and, indeed, the demands are met mainly by the cathode-ray tube (c.r.t.). Flat cross-bar addressed displays, however, are being introduced to challenge the c.r.t., the most advanced being the gas-discharge plasma panel. The technologies determine the display output characteristics and dictate largely the drive circuits. This review is, therefore, oriented towards devices, with the major technologies being described in detail. The display market is a large one and there is extensive continuing research and development to improve present performance. The main advances and innovations are also outlined. In spite of the effort involved, none of the devices offers the ideal display module, and how closely the requirements of the electronic engineers can be met in the various types of equipment by available devices provides the main theme of the review. - Author(s): M.F. Radford
- Source: Proceedings of the Institution of Electrical Engineers, Volume 125, Issue 11R, p. 1100 –1112
- DOI: 10.1049/piee.1978.0246
- Type: Article
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Electronic scanning allows the direction, shape, or rate of change of direction of an antenna beam to be varied faster than is possible by mechanical movement of the aperture. The principal application is in advanced radar systems. Scanning may be in one or two dimensions, using linear, planar, circular or orthogonal apertures. Control may be by mechanical, ferrite, diode or circuit-type phase shifters, or by frequency variation. This control may be applied directly to the aperture, or indirectly by means of some collimation system. The most cost-effective solution to any given scanning problem is usually the configuration that provides no more facilities than the application is able to exploit. During the last two decades, antenna-scanning capabilities have exceeded requirements and few advanced systems have gone into production. However, appropriate applications are now emerging, and a steady but unspectacular growth in electronic scanning may be expected. - Author(s): D.M. Rowe
- Source: Proceedings of the Institution of Electrical Engineers, Volume 125, Issue 11R, p. 1113 –1136
- DOI: 10.1049/piee.1978.0247
- Type: Article
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Thermoelectric generators have no moving parts, are silent in operation and are compact, and, when coupled to an isotropic heat source, can operate unattended over long periods in inhospitable and inaccessible environments. In recent years, thermoelectric generators have found increased application in situations where combinations of their desirable properties outweigh their relatively high cost and low generating efficiency. This paper reviews the present ‘state of the art’ of generating electricity by the thermoelectric effect and looks at future prospects. A brief history of thermoelectricity is followed by definitions and an introduction to its basic theory. Factors that influence the selection of materials for a particular application are discussed, together with the preparation and properties of established materials. A Section dealing with the fabrication of thermoelements and the various configurations employed in module construction is followed by a general discussion of thermoelectric generators. These are divided into two types: nonisotopic powered and isotopic powered. Emphasis is placed on the latter, and applications of this type of generator are covered in some detail. The conclusion is reached that the development and application of thermoelectric generators is assured with the continuation of the US space programme, with radioisotopic thermoelectric generators (r.t.g.s) providing onboard power for deep-space missions. In marine applications, the requirement for isotopic-powered generators in submerged situations will increase, whereas their prospects in surface and terrestrial applications is not so certain. From an economic point of view, it seems unlikely that the use of radioisotopic generators can be justified in situations where air is available to burn hydro carbon fuel. In situations where it is difficult to get fuel to the site, a thermomechanical generator provides a possible alternative to thermoelectric generators. In medical applications, particularly the nuclear-powered cardiac pacemaker, the future is more promising. Less risk to the patient results from the use of a nuclear-powered pace maker than from chemical batteries, and, as for environmental objections, the Fuel Directorate of Licensing have made it clear that their social and economic benefits far outweigh the social and economic costs. - Author(s): J.E. Gould
- Source: Proceedings of the Institution of Electrical Engineers, Volume 125, Issue 11R, p. 1137 –1151
- DOI: 10.1049/piee.1978.0248
- Type: Article
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The review gives an initial survey of magnetic units, the hysteresis loop, domain theory, crystal and shape anisotropy, single-domain particles, self-demagnetising field and demagnetisation factors, the criteria for permanent-magnet materials, and the methods and conditions for magnetisation of magnets. This is followed by an outline of the properties and production methods for those materials now in wide use. Cast or sintered Alnico alloys require field heat treatment to produce a structure of very small elongated single-domain particles in a nonmagnetic matrix. The range of properties obtainable by composition variation is exemplified. Magnets in these alloys are usable from extreme subzero temperatures to about 600° C. The ceramic barium/strontium ferrite magnets depend on the production of an array of single-crystal particles of the size for single domains. Remanence values are lower than for Alinico alloys but coercivity is substantially higher. The widely used flexible-strip magnets are obtained by plastic bonding of the same single-crystal particles. The recently developed cobalt/rare-earth metal magnets give uniquely high properties but with high material cost and difficult production methods. Other permanent magnet materials have limited uses. A short note on comparative costs is given. The factors controlling magnet stability are outlined and the limitations of the various materials discussed. The wide range of permanent-magnet applications are discussed under the classifications of electromechanical (speakers, measuring instruments, eddy-current devices, motors and generators), ion and electron-beam control (magnetrons, travelling-wave tubes) and magnetomechanical (holding and lifting, drives, repulsion devices) - Author(s): B. Jones and R.T. Waters
- Source: Proceedings of the Institution of Electrical Engineers, Volume 125, Issue 11R, p. 1152 –1176
- DOI: 10.1049/piee.1978.0249
- Type: Article
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The nature of recent international research collaboration is described. Breakdown data obtained on a wide variety of air clearances are comprehensively summarised; the effects of the polarity and shape of the testing impulse, the geometry of the electrodes and the condition of the atmosphere are considered separately. Recent improvements in the physical understanding of the pre-breakdown phenomena are discussed in some detail, and their application to engineering problems, by means of models, is considered. Newly developed methods of field calculation are applied to complex configurations subjected to more than one voltage stress. Statistical methods are used, both in assigning confidence intervals to test data, and in predicting risks of failure. - Author(s): D. Gray
- Source: Proceedings of the Institution of Electrical Engineers, Volume 125, Issue 11R, p. 1177 –1194
- DOI: 10.1049/piee.1978.0250
- Type: Article
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The review gives a very brief history of the early days of the use of electric power at sea in commercial ships and then proceeds to the post-1960 period when marine systems changed from d.c. to a.c. Before system design is considered, the constraints imposed on designers are dealt with, such as the marine ambient conditions and the activites of regulatory bodies such as classification societies, statutory authorities and the Intergovernmental Maritime Consultative Organisation. Some recent statistical information is provided on d.c. and a.c. systems, choice of system frequency and voltage and relative sizes of installed generating capacity. System layout is described and the arguments in favour of earthed or insulated systems reviewed. Factors in the selection of generating plant are discussed and the need for voltage regulation and frequency regulation. This lead to the evaluation of system short-circuit currents and their inter-relationship with installed generating capacity and voltage regulation. Protection, installation of switchboards and cable construction are described. The problems associated with electrical installations in tankers (oil, gas and chemical) are outlined and some comparison made with tanker safety practices and safety practices employed in petrochemical plants ashore. Control and instumentation systems are then described. The history is briefly outlined leading to the present state where control arrangements are such that watchkeepers are withdrawn from the machinery spaces. System safety aspects and protective measures are described and operational experience to date outlined. A brief history of the modest use of computers at sea to date is included. This then leads to a forecast for future developments in marine control engineering. Finally, the review concludes by describing the equipment designed for use in the bridge area and the need for such equipment. Static electricity, electromagnetic compatibility and electric propulsion have not been dealt with in this review.
Alphanumeric display
Electronically scanned antenna systems
Thermoelectric power generation
Permanent magnets
Air insulation at large spacings
Marine electrical installations
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