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Electrical Engineers, Proceedings of the Institution of

Issue 10  Part R • Date October 1973

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Displaying Results 1 - 6 of 6
  • Techniques of frequency synthesis

    Publication Year: 1973 , Page(s): 1057 - 1077
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2303 KB)  

    A brief outline of the initial development of synthetiser techniques is followed by a description of two early types, and reference is given to a comprehensive survey in the late 1960s. The concurrent advance in solid-state technology has had a major impact on synthetiser development, mainly in regard to divider- and voltage-controlled-oscillator techniques, resulting in improved performance combined with reductions in size, weight, power consumption and cost. For economic viability, synthetisers must be designed for specific systems, and a section is devoted to the requirements for several systems. To meet such requirements, descriptions are given of the techniques used in a number of synthetisers, both variable-divider/voltage-controlled oscillator types and others. Although mainly in the h.f. band, examples are also given in the audio, v.h.f. and u.h.f. bands. Economic aspects are considered in regard to relative performance and to equipment replaced by synthetisers. As all synthetiser output frequencies are derived from a single master source, the reliability of this oscillator is of paramount importance. Finally, it is noted that miniaturisation has tended to reduce v.c.o. output to a level which makes noise-performance requirements difficult to achieve. View full abstract»

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  • Surface-acoustic-wave components, devices and applications

    Publication Year: 1973 , Page(s): 1078 - 1110
    Cited by:  Papers (16)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (5201 KB)  

    Since the mid-1960s, there has been a strong upsurge of interest in the propagation of surface acoustic waves on solids. The stimulus for this interest came from the realisation that simple, compact, and potentially cheap surface-acoustic-wave devices could be made which performed valuable signal-processing functions principally at intermediate frequencies. In a very short space of time these devices have met demanding specifications and have been accepted for military systems. This article reviews the recent work on surface acoustic waves (s.a.w.s) with the main emphasis on devices and applications. The introductory section provides basic background information on the nature, propagation and transduction of s.a.w.s. In some s.a.w. devices, propagation of the surface wave is influenced by surface structures which reflect, couple, guide or amplify the wave, and these are reviewed prior to the main section which is devoted to the more important s.a.w. devices, i.e. delay lines, tapped delay lines, frequency filters, oscillators, fixed and programmable analogue matched filters, convolvers and correlators, and finally, devices related to displays. Surface-wave devices are beginning to have an impact in both radar and communications systems. Both these areas of application are reviewed with particular reference to code generation and matched filtering (pulse compression) for high-performance radars, correlation systems for simple radars, synthetic-clutter generation for clutter-reference radars, compressive receivers, processors for fusing and filters for acquisition of synchronisation in communication systems. At appropriate points in the review, basic limitations of s.a.w. devices are indicated and the competition offered by other devices is assessed. View full abstract»

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  • Large a.c. motors

    Publication Year: 1973 , Page(s): 1111 - 1132
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    This review covers the range of basic large a.c. motors, comprising squirrel-cage and slip-ring induction, synchronous and a.c.-commutator motors, in the output range of 1¿20/30 MW, and the size range of 0.5¿30 kW per rev/min, with centre heights ranging from 450 to 1250 mm. The underlying theme may be described in general terms as `system design¿ in the widest sense; i.e. the effect of the environment on motor design and application, and vice versa. Thus, amongst the major topics covered are stator-insulation requirements and techniques, with particular reference to the surge voltages encountered in modern supply systems that have high short-circuit capacities. This leads to the consideration of system-stability problems on the one hand, and the choice of enclosures on the other. Conversely, the effect of motors on the environment, e.g. noise and the problems of heat removal (again affecting the choice of enclosures) are dealt with as complementary problems. With respect to motor design proper, emphasis is placed on aerodynamic and thermodynamic problems, and the importance of 2nd-order electromagnetic phenomena and reliability. To allow the reader to obtain detailed information (which cannot be covered in a broad survey of this type) on specific subjects, a carefully selected list of relevant references is given. View full abstract»

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  • Electricity in horticulture

    Publication Year: 1973 , Page(s): 1133 - 1164
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (7658 KB)  

    British horticulture has developed from a way of life to an industry run on factory lines, where all facets of growing, from seed sowing to marketing, depend on precise control of the environment and maximum operating efficiency. The need to improve the output and quality of greenhouse crops has demanded a strict control of plant climate; the increasing cost of labour, the drift of workers to factories and the restriction of the working week to five days has forced growers to adopt mechanised and automatic methods from seed sowing to harvesting. In 20 years the industry has progressed from using practically no electricity to being completely reliant upon it. A grower without a standby generator could face serious financial loss. Although electricity is not used as a source of heat except in very small holdings, it is essential for ancillary equipment and for the close control of the plant climate, with automatically operated heating, ventilating and watering systems. Concentrating the heat where it is wanted (e.g. in the soil or on the bench) with soil-warming cables can effect economies. There are spectacular results being obtained by using supplementary lighting and propagating plants in a completely controlled environment (i.e. a growing room where heating, ventilating, watering and lighting are provided). The increasing use of ?nightbreak? and ?dusk-to-dawn? lighting enable crops to be produced all the year round to meet market requirements. There are improved methods of rooting cuttings and germinating seeds under intermittent mist, and also of germinating seeds in a germinating cabinet. The grower relies on electric power to shred and mix composts, fill pots, make soil blocks, plant and gather many crops, move material about the holding, and to pump water for irrigation and frost protection of field crops. There is an increasing use of cool stores to hold cuttings until the propagating benches are ready, to store fruit, vegetables and flowers for a favourable - - market, and to remove quickly field heat from greenhouse and field crops as the first step of a cool chain from grower to consumer. Air-supported plastics houses are an alternative to rigid structures, one such experimental ?house? having rigid sides and an inflated roof. Mushrooms are a crop with considerable potential here as air conditioning in the growing sheds is now essential for maximum crop output. The British horticulture industry still needs extensive research and development to be done, particularly in the full and economic use of all forms of lighting for plant production. View full abstract»

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  • Computer-controlled road-traffic signal systems in the United Kingdom

    Publication Year: 1973 , Page(s): 1165 - 1180
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2739 KB)  

    The paper is concerned with dynamic control, and, in particular, traffic-signalling systems that use computers as the controlling element. In the UK, such systems have two principal applications: the first deals with traffic problems in cities and towns, and the other applies to motorways. Area traffic control is the name given to those systems that apply to cities and towns, and traffic control for motorways is provided for by the motorway communication system. These systems have evolved at different times and for different reasons, and are fundamentally different in their operation, and so are dealt with separately. The history of traffic control, the development of computer-controlled traffic-signalling systems and their subsequent implementation are described, as are types of detector now in use and current research projects. View full abstract»

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  • Ergonomics in control

    Publication Year: 1973 , Page(s): 1181 - 1192
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2074 KB)  

    Discussions of completely automatic plants, pilotless aircraft and other fantasies of the automation euphoria have now become outmoded and replaced by more rational considerations concerning the proper integration of men into complex systems. Ergonomics is the technology concerned with the application of the human sciences to problems of the effective deployment of manpower. This review attempts to outline the history and scope of ergonomics, and to indicate the types of problems which arise and the general way in which solutions are approached. A brief account is provided of the nature of human abilities, and the ways in which such knowledge should be applied to the design of equipment and systems. The object throughout is to provide a frame of reference, indicating the types of questions which require to be asked and answered. No attempt is made to provide a compendium of detailed facts and figures for designers to use. 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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