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

Issue 4 • Date April 1987

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Displaying Results 1 - 16 of 16
  • Eddy currents in a rectangular toroid

    Page(s): 309 - 316
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (826 KB)  

    Eddy currents flowing in a metallic toroid of rectangular section modify the mutual resistance and mutual inductance between a pair of windings around the metal. These effects can be used to determine the metal's conductivity. This paper presents a two-dimensional analysis of the process, using a Green's function method to determine the magnetic field, from which the resistance and inductance are derived. The results are compared both with a one-dimensional theory and with experimental data. View full abstract»

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  • Assessment and improvement of electric-field measurements using a bias probe with particular reference to twin-point-plane geometry

    Page(s): 317 - 327
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1192 KB)  

    A commonly used method of measuring current density and electric field at the surface of an electrode is by the use of a bias probe which is inserted into the contours of the electrode. Values of the electric field can be found by applying a bias voltage to the instrument and measuring the ratio of received currents, with and without this bias voltage in operation. The field strengths are then read off a previously obtained calibration curve. These curves are all obtained under the assumption that the current densities and electric fields to be measured are constant in the vicinity of the instrument. Such direct use of the calibration curves in regions with significant spatial field variations are here shown to give spurious results, for example there are large oscillations in field measurements as a probe traverses an abrupt change in current. The anomalies are well exhibited by measurements on a twin-point-plane corona discharge in air, and the behaviour has been explained and quantified by using a simple model. An improved measurement procedure has been developed for such situations. This has been expedited by fitting an analytic curve to the calibration and then programming a method which uses adjacent readings to predict the field strength. The anomalous readings have been shown to be false, and significant overestimates of the field strength can be avoided by following the procedures described in the paper. View full abstract»

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  • Book review: Accounting for Profit with the IBM PC

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    Freely Available from IEEE
  • Eye word processor (EWP) and peripheral controller for the ALS patient

    Page(s): 328 - 330
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (435 KB)  

    The authors have designed an eye word processor (EWP) controlled by eye movements for victims of amyotrophic lateral sclerosis (ALS). Instead of unnatural side-to-side eye movement or blinking, the system employs the eye's natural focusing movements. It allows a patient to input eight letters per minute, call a nurse, or control certain appliances. It takes only five minutes to set up, and it has been praised by nursing staff. View full abstract»

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  • Instrument for real-time measurements of airgap flux distribution of on-load synchronous generators

    Page(s): 331 - 334
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (441 KB)  

    The behaviour of airgap flux of synchronous generators was studied and a measurement method for airgap flux density distribution was established. Based on these results, a microprocessor-based instrument for the measurement of airgap flux density distribution has been developed. The authors describe this instrument, by the use of which it is possible to measure exact airgap flux distribution of on-load synchronous generators in real time. View full abstract»

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  • Fast measurement of active and reactive power in three-phase systems

    Page(s): 335 - 338
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (447 KB)  

    The paper presents a new method to measure the active and reactive power in three¿¿phase systems. The method is based on the space vector formulation, which uses the instantaneous values of voltages and currents in a three-phase system. The work with instantaneous values allows the authors to obtain the instantaneous active and reactive power, because the measuring circuit requires no filters or integrators. The circuit is used in a transistor rectifier, which includes the control of the reactive component of the input currents. The convertor has sinusoidal input currents and these currents keep in phase with the source voltages independent of the amplitude and polarity of the load current, which means operation with optimum power factor without requiring reactive power. These results confirm that the measuring circuit can be used in high-quality reactive-power compensators for critical loads. View full abstract»

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  • Contactless measurement of mechanical vibrations based on the Doppler effect

    Page(s): 339 - 342
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (459 KB)  

    The paper presents a contactless measurement of mechanical structure vibrations based on the Doppler effect. The range of the measured velocities and amplitudes of the mechanical vibrations and the errors of the measurement method are analysed. The range of applicability of the method as well as measurement results of the vibrations of a loudspeaker and a loudspeaker cabinet are also presented. View full abstract»

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  • Fachw¿¿rterbuch Energie- und Automatisierungs-Technik. A Dictionary of Power Engineering and Automation. Part 1

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    Freely Available from IEEE
  • Dictionary of Electrical Engineering and Electronics

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    Freely Available from IEEE
  • Arbitration in mechanical and electrical engineering

    Page(s): 343 - 349
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1165 KB)  

    An introduction to arbitration in engineering, for those unfamiliar with this means of determining all kinds of dispute: it is available provided that both parties are agreeable, and the awards are legally binding. The main purpose is to find a swift and just settlement, preferably in such a way that other social and commercial relationships are not soured. It is usual for the arbitrator to have some knowledge of the general subject, and of the law as it affects the matters in dispute. Most cases in engineering arise from standard conditions of contract and, if there is not mutual agreement, either party can apply to the President of the appropriate Institution to appoint an arbitrator, or he may be appointed by the Court, usually from the list of the Chartered Institute of Arbitrators. International cases where two countries are involved may be taken to a third, for example to Switzerland. These proceedings have the advantage of privacy and simplicity, and parties need not be represented by lawyers, although it is wise to take legal advice initially. Sometimes when the parties see their differences clearly set out, they may find it easier to agree to some settlement, and save the expense of a full hearing. The 1979 Act provides a procedure for the appeal of awards, and for the Court to act when one party has failed to comply. View full abstract»

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  • Book review: The Technical History of the Beginnings of Radar

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    Freely Available from IEEE
  • The Cambridge Scientific Instrument Company from 1881 to 1968

    Page(s): 351 - 358
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1784 KB)  

    The author, a past employee of the company, traces its early history from the time, in 1878, when Robert Fulcher and Albert George Dew-Smith began making instruments commercially in Professor Stuart's departmental workshop at Cambridge University. The company's name originated in 1881 when Horace Darwin entered into partnership with Dew-Smith, Darwin, who subsequently became sole owner, was regarded as a father figure by the firm's employees. Reference is made to a number of the innovative instruments for which the company became world renowned. The narrative concludes with the takeover of the company by the George Kent Group in 1968. View full abstract»

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  • 1985 Parsons Memorial Lecture 1884: the rebirth of steam power

    Page(s): 359 - 368
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1669 KB)  

    In the early 1880s the steam engine was considered to be obsolescent and it was predicted that the internal combustion engine would become the more efficient machine of the future. Both engines relied on the conversion of reciprocating to rotary motion, and thus their speed and output were limited by inertial forces. The paper suggests that in 1881 Parsons foresaw that the infant market for distributed electricity would develop into one of immense size requiring prime movers of vastly increased powers, and that his initial ideas were centred on a rotary internal combustion engine. The paper describes the 1884 Patents, their practical details and their wide coverage. Parsons had to circumvent them when he lost their use in 1890, and it is a measure of his immense determination and courage that he persevered both to win through to the ultimately successful exploitation of his inventions in the field of electrical generation, and also to establish his steam turbine for marine propulsion. Any major innovation requires a long term and absorbs much effort and money before its exploitation yields financial returns. This fact is as true today as it was at the end of the 19th century. View full abstract»

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  • Book review: Mathematical Methods in Electrical Engineering

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    Freely Available from IEEE