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1887

Proceedings of the Institution of Electrical Engineers

Volume 121, Issue 4, April 1974

Volumes & issues:

Volume 121, Issue 4

April 1974

Application of dispersive networks in data-transmission receivers
Decision-directed delay-lock loop using fast Fourier-transform crosscorrelation
  • Author(s): S.S. Haykin  and  C.M. Thorsteinson
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 121, Issue 4, p. 245 –248
  • DOI:  10.1049/piee.1974.0046
  • Type: Article
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  • p. 245 –248 (4)
    A decision-directed delay-lock loop is described using the fast Fourier transform (f.f.t.) for cross-correlation, together with decisions based on maximum likelihood. The f.f.t. produces a complete set of lagged products of the received echo and the delayed replica of the transmitted signal. This enables the loop to realise a wide dynamic range. Another useful feature of the loop is that it has the ability to detect unlocking and to switch automatically between the modes of acquisition, tracking, and detection of unlocking and reacquisition.
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Use of practical circuits switched with alternating polarity
Theory of cylindrical monopole antennas immersed in conducting media
Polynomial approach to study of single-ring circular antenna array
Effect of scattering by rain on radiometer measurements at millimetre wavelengths
Analytical expression for prediction of F0E for solar zenith angles 0–78°
Thyristor chopper control and the introduction of harmonic current into track circuits
  • Author(s): T.J. Lowe  and  B. Mellitt
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 121, Issue 4, p. 269 –275
  • DOI:  10.1049/piee.1974.0052
  • Type: Article
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  • p. 269 –275 (7)
    Alternating currents will generally be present in a d.c. traction supply owing to the action of synchronously switched power-control equipment and also to the presence of mains-frequency-harmonic voltage ripple. This paper describes the factors that determine the magnitude and frequency of such current in the power rails, for various conditions of d.c.-chopper operation. Models that describe the introduction of harmonic current into track circuits are developed from power-circuit considerations, and theoretical predictions are compared with practical results obtained from measurements undertaken by London Transport. The use of multiphase chopper equipments to reduce the size of the input filter is considered, and it is shown that, when normal-load unbalance conditions are considered, no advantage is gained by using more than two phases.
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Field-theory analysis of saturation harmonics in induction machines
Approximate frequency-response values for transmission-line transient analysis
  • Author(s): R.G. Wasley  and  S. Selvavinayagamoorthy
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 121, Issue 4, p. 281 –286
  • DOI:  10.1049/piee.1974.0054
  • Type: Article
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  • p. 281 –286 (6)
    To reduce computational effort when evaluating the transient response of multiconductor transmission lines, a simplified means of obtaining frequency responses is described. The method employs the concept of frequency-independent modal matrices, and in this respect involves an approximate application of the theory of natural modes. Together with the modified Fourier transform, it is used to provide the transient-response characteristics of typical line configurations found in practice. Furthermore, these results are compared with those obtained more precisely, so as to indicate the high order of accuracy that is possible.
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Laboratory tests of self-cleaning properties of polluted high-voltage insulators
  • Author(s): J.L. Diesendorf  and  T.M. Parnell
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 121, Issue 4, p. 287 –292
  • DOI:  10.1049/piee.1974.0055
  • Type: Article
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  • p. 287 –292 (6)
    The ability of insulators in a polluted environment to benefit from rain washing may significantly influence their service performance. A number of laboratory tests designed to assess self-cleaning properties were applied to a selected group of insulators. Orders of merit based on various criteria have been compared and found to differ with variations in test procedure. It is concluded that no single test can be prescribed at this time. It is recommended that future laboratory investigations be based on an analysis of data on the rain washing of insulators in service and in natural-pollution testing stations.
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Discussion on “Calculation of the external thermal resistance of buried cables through conformal transformation” and “Moisture control of cable environment with particular reference to surface troughs”
Stability study of controlled rectifiers using a new discrete model
Erratum: Large a.c. motors
Erratum: Rectifier action with constant load voltage: infinite-capacitance condition
Relay control of undamped linear systems using Lyapunov's second method
Analysis of nonlinear time-varying discrete systems by the use of multidimensional Z transforms
  • Author(s): N.C. Jagan  and  R.C. Desai
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 121, Issue 4, p. 307 –309
  • DOI:  10.1049/piee.1974.0061
  • Type: Article
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  • p. 307 –309 (3)
    Two methods based on the functional approach are presented for the solution of nonlinear time-varying discrete systems. The first method is based on the successive-approximation method due to Higgins and Ridings, and the second method is based on the technique proposed by Bansal for nonlinear continuous systems. In both the methods, the analysis is carried out in the multidimensional Z domain. They yield analytical expressions for the approximate transient response, and hence afford considerable insight into the physical system. Moreover, these methods are simple and straightforward in their application.
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Computer-aided design procedure for reduced-order observers

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