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Physical Science, Measurement and Instrumentation, Management and Education - Reviews, IEE Proceedings A

Issue 8 • Date November 1982

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Displaying Results 1 - 8 of 8
  • Electromagnetic suspension and levitation

    Publication Year: 1982 , Page(s): 549 - 581
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (5289 KB)  

    The phenomenon of levitation has attracted attention from philosophers and scientists in the past. Recent advances, notably in power electronics and magnetic materials, have focused this attention within the last decade on the application of electromagnetic suspension and levitation techniques to advanced ground transportation. Regardless of the fact that there is, in effect, a separate technology involved for each electromagnetic method, the whole subject is given a blanket title of `maglev¿¿. There is also a very wide range of industrial applications to which magnetic suspension techniques could be profitably applied, particularly in the area of high-speed bearings to reduce noise and to eliminate friction, and yet it is only high-speed ground transportation that has caught the imagination of the media. The review deals with the physics and engineering aspects of the four principal contenders for advanced ground transportation and describes the most up to date developments in Germany, Japan, the USA and the UK in this field. The review also describes some of the very recent challenging developments in the application of electromagnetic suspension and levitation techniques to contactless hearings. A fairly comprehensive bibliography is given to enable the more interested reader to pursue the topic further in any one of the technologies dealt with in the paper. View full abstract»

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  • Electromagnetic properties of a circular cylindrical coil in a set of planar ferromagnetic regions

    Publication Year: 1982 , Page(s): 582 - 589
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (884 KB)  

    A general form of analysis is described for a solenoidal coil immersed in a set of ferromagnetic regions. The axis of the coil is perpendicular to the planar regions. Expressions are developed for power flow, impedance and normal force. Use is made of the Hankel transform and a transmission-line analogue. Results obtained agree with those calculated by previous authors. A phenomenon reported by E.R. Laithwaite is analysed. The method offers economies in effort and computing time. View full abstract»

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  • Current density in thin nonmagnetic tapes induced by the short-circuit current

    Publication Year: 1982 , Page(s): 590 - 592
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    A method of calculation of the current density in thin nonmagnetic tapes, which are generated by the short-circuit current flowing through parallel conductors, is presented. The method discussed is based on the integral formulas for the time-domain response of linear systems and the integral equation with respect to the space variable is applied. As an example, current density as a function of position and time is given. The method presented can be applied to solve problems concerning transient processes occuring in linear systems of complex form. View full abstract»

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  • Relationship between various measurement techniques for void discharges

    Publication Year: 1982 , Page(s): 593 - 606
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1303 KB)  

    The paper examines three insulation-measurement techniques, individual discharge measurements, conventional power frequency bridge techniques and the charge-transfer oscillogram; and shows the theoretical link between the results of each. The theoretical predictions are confirmed by experimental results on an artificial void model. This model demonstrates that, for a given voltage above discharge inception, two discharge states are possible. In practice, the void oscillates between the two states and noninteger values of average number of discharge per cycle are produced. A linear relationship between average number of discharges and voltage is observed. Consideration is given to the form of charge-transfer oscillograms, and the conductance and capacitance voltage curves, implied by an idealised trace growing in the specified manner, are given. View full abstract»

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  • Effect of temperature on the impulse life expectancy of crosslinked polythene

    Publication Year: 1982 , Page(s): 607 - 610
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    The Weibull statistical method is widely used to predict the failure of electrical insulation in terms of stress and time (or, in this case, the number of applied impulses) for a given temperature. In the present work the probability of breakdown has been determined for flat-disc samples of crosslinked polythene, subject to repeated application of impulse voltages for various stresses and temperatures. The results obtained indicate that an extension of the Weibull equation to include temperature is valid. Hence the probability of failure P for a given number of impulses n with the sample at stress E and temperature T is given by P(E, n, T) = 1 ¿¿ exp[¿¿(E/E0)b ¿¿ (n/n0)a ¿¿ (T/T0)c], where E0, n0 and T0 refer to a probability value of 63.2% View full abstract»

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  • Self-magnetic effects in a model gas-blast circuit breaker at very high currents

    Publication Year: 1982 , Page(s): 611 - 618
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (935 KB)  

    Substantial self-magnetic effects are anticipated within the arc columns of gas-blast circuit breakers at very high currents (10¿¿100kA). The paper reports measurements of gas pressure within the arc column, at the tip of the upstream electrode in a model gas-blast circuit breaker, which, along with a knowledge of the ambient gas pressure, yields values for the pressure elevation due to self-magnetic effects. The results of the investigation confirm the exitence of such self-magnetic effects but indicate that for peak currents in excess of typically 20kA the self-magnetic pressure elevation is less pronounced than predicted by simple theory. There is evidence that these abnormally low magnetic pressures are due to increased swirl of the arc plasma at high-current levels. Possible consequences of such a plasma swirl in relation to current-zero arc behaviour are considered. View full abstract»

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  • Design of two-dimensional electrodes by the field-plane method

    Publication Year: 1982 , Page(s): 619 - 624
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (610 KB)  

    An extension of the Schwarz-Christoffel transformation is applied to the design of two-dimensional electrodes, subject to specified field strengths, when placed in the vicinity of a plane insulating wall. It is shown that the nonclosure of the resulting profiles limits the degree of field uniformity that can be prescribed. Finally, a condition for closure is proposed and an example of a closing electrode is given. View full abstract»

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  • Large-scale project management

    Publication Year: 1982 , Page(s): 625 - 633
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1337 KB)  

    A forum on the total management of large-scale projects was organised within the Management & Design Division of the IEE,* with the objective of providing an interchange of ideas among engineers actively engaged in this field, at superior levels of responsibility. Part 1 of this record of the forum is a summary of the introductory address by Vice Admiral Sir Lindsay Bryson, who traced the history of project management in the defence procurement sphere, leading to the recent trend towards placing management responsibility with a prime contractor in industry, taking as an example the Sting Ray torpedo project. The participants in the forum comprised some thirty invited members from the fields of industry, research and development, the public sector, and the armed services. They were invited to discuss a number of problem areas, and their views and experience have been collated and summarised in Part 2. This is intended to serve as a primer and checklist to assist those who are required to engage in such projects. It is proposed to initiate a further study of how project experience may be recorded, and to develop a recommended code of practice. View full abstract»

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