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IEE Proceedings A (Science, Measurement and Technology)

Volume 139, Issue 4, July 1992

Volumes & issues:

Volume 139, Issue 4

July 1992

Electromagnetic field energy containment
  • Author(s): V.G. Endean
  • Source: IEE Proceedings A (Science, Measurement and Technology), Volume 139, Issue 4, p. 137 –140
  • DOI:  10.1049/ip-a-3.1992.0024
  • Type: Article
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  • p. 137 –140 (4)
    An electromagnetic virial relation in cylindrical geometry is derived which shows that limits on field energy containment imposed by the tensile strength of containment structures can be circumvented. The result is illustrated by two possible machines for which there is a much weakened theoretical virial constraint on the containment of field energy and which should be practically realisable with low dissipation. Not only do these machines represent potentially very useful high energy storage devices given development of appropriate technology, but also, one of them provides helpful insights into the dipolar rotating electric field model of ball lightning with confinement of electromagnetic field energy by atmospheric pressure.
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Criterion for the performance analysis of synchronous and asynchronous sampling instruments based on nonlinear processing
  • Author(s): M.A. Catelani ; G. Iuculano ; D. Mirri ; F. Filicori ; A. Menchetti
  • Source: IEE Proceedings A (Science, Measurement and Technology), Volume 139, Issue 4, p. 141 –152
  • DOI:  10.1049/ip-a-3.1992.0025
  • Type: Article
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  • p. 141 –152 (12)
    We propose a criterion for the comparison of different sampling strategies (synchronous, asynchronous and random) and filtering algorithms used in digital instruments which provide the estimate of the time average of a signal processed with a nonlinear conversion of multiple inputs (e.g. wattmeters, RMS voltmeters,…). This criterion uses the Bayesian approach to incorporate, for every sampling strategy, any prior information on the influences of each incidental quantity which can vary the output of the instrument, transforming this output into a statistic. The asymptotic mean-squared error of the measurements has been assumed as an estimator of the error and its general expression, valid for the most common sampling strategies used in practice, has been deduced. This asymptotic error is a function of the frequency response of the digital filter used and, eventually, of the characteristic function of the probability distribution selected for the random variables generating the sampling instants. Finally, the particular formulae for different sampling strategies and filtering algorithms are discussed and compared.
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Chronic disease management supported by informatics: example diabetes
  • Author(s): I.D. Nussey
  • Source: IEE Proceedings A (Science, Measurement and Technology), Volume 139, Issue 4, p. 153 –160
  • DOI:  10.1049/ip-a-3.1992.0026
  • Type: Article
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  • p. 153 –160 (8)
    The management of chronic health care conditions already consumes more than half of all health care expenditure in developed countries. Well before the end of the century, demographic trends will make current arrangements unaffordable. Fortunately, advances in medical and scientific knowledge, together with increasingly affordable and pervasive information technology (IT), make it possible to anticipate the delivery of good preventive management and the best clinical practice, closer to the patient, which can simultaneously improve the quality of patient care and provide substantial cost benefits. This paper describes the investigations made by the Eurodiabeta Consortium with regard to diabetes, a lifelong condition affecting more than 2% of the population. Partly funded by the European Community's Advanced Informatics in Medicine (AIM) framework programme, the Eurodiabeta Consortium comprised 16 complementary clinical, medical informatics and industrial partners, drawn from seven countries. Progress is reviewed and the opportunities and challenges ahead are explored. Other aspects covered are the Consortium's approach to the sensitive and crucial consideration of medical quality assurance, experience working with the European Commission, and the non-technological factors-social, economic and political—which must be addressed in the runup to bringing Eurodiabeta-type products into the market place.
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Photoacoustic and photothermal deflection spectroscopy of semiconductors
Influence of space charge on field emission of electrons from sharp edges
  • Author(s): C.B. Wheeler
  • Source: IEE Proceedings A (Science, Measurement and Technology), Volume 139, Issue 4, p. 169 –173
  • DOI:  10.1049/ip-a-3.1992.0028
  • Type: Article
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  • p. 169 –173 (5)
    A sharp-edged cathode and its adjacent anode are represented as a section of a pair of coaxial cylinders with an inner radius r0 and an outer radius r1 The field emission current density J is determined as a function of the anode voltage V1 and the cathode work function potential φ for degrees of space-charge that lead to a cathode field E in the range 0.9 E0 ≤ E ≤ E0, where E0 is the cathode field when there is no current flow. In the case where eV1 ≪ mc2 there is a particular value of J which is dependent on r0, r1, φ but independent of V1, for which space-charge effects have caused the current to be reduced to half of the emission current appropriate to the field E0. It is shown that this current is of particular significance to the experimenter when designing a field emission diode which uses a razor blade cathode. In SI units this reduced current density is: J = .86×106r00.423r1−0.997φ2.657
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Potential gradient measuring device based on a partial method
Current shunts and resistors in use in NAMAS accredited laboratories
Statistical process control in PCB manufacture: what are the lessons?
  • Author(s): B.G. Dale  and  P. Shaw
  • Source: IEE Proceedings A (Science, Measurement and Technology), Volume 139, Issue 4, p. 182 –188
  • DOI:  10.1049/ip-a-3.1992.0031
  • Type: Article
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  • p. 182 –188 (7)
    A number of printed circuit board (PCB) manufacturers perceive that they face difficulties in the application of statistical process control (SPC). The difficulties include the product characteristics and process parameters to be measured and charted, the mix of different manufacturing technologies, the inherent variability of the chemistry used in the process, the interconnecting nature of the processes, small batch production runs, and the concept of performance-based charts. This paper reports and examines the most common queries raised by representatives of the industry under the broad headings of: application, type of control chart and its design, interpretation, and capability.
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Electromagnetic theory without electric flux
  • Author(s): C.J. Carpenter
  • Source: IEE Proceedings A (Science, Measurement and Technology), Volume 139, Issue 4, p. 189 –209
  • DOI:  10.1049/ip-a-3.1992.0032
  • Type: Article
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  • p. 189 –209 (21)
    Whereas, to the physicist, the electric field in space is completely described by the field vector E, engineers commonly add the flux density, or displacement vector D as a separate quantity, and many regard the SI units as endorsing the need for two different vectors. The paper examines the practical implications of a treatment which makes the concept of electric flux unnecessary by concentrating attention on the charges. The electric field is defined as the potential φ, and its gradient becomes an auxiliary function, thus reversing their customary roles. The distinction between what is meant by the terms ‘electric’ and ‘magnetic’ also changes. It is shown that this approach has advantages in electrostatic theory, clarifies the concept of potential datum, and gives an entirely different view of electromagnetic propagation. Energy radiation is described in terms of the behaviour of the charges instead of the fluxes and characterises most electromagnetic devices. It resolves into two different components, one due to the vector A in magnetic devices, and the other, due to φ, defines those operating electrically, which are considered explicitly in the paper. The energy transfers sum to zero, unless the time delays within the system are significant, when a net energy radiation appears as a dissipative component instead of a stored energy. Retardation is accepted as an empirical observation, making the concepts of displacement current and flux inter-linkages unnecessary. It is shown that one of the consequences of the changes is to remove an apparent anomaly between classical theory and quantum mechanics, as φ, not E, appears in the Schrödinger equation.
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Conditions for coalescence of multiple electric discharges

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