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Electrical Engineers, Proceedings of the Institution of

Issue 2 • Date February 1975

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Displaying Results 1 - 25 of 40
  • Data transmission with variable-redundancy error control over a high-frequency channel

    Publication Year: 1975, Page(s):113 - 118
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (618 KB)

    Results of computations and field tests on a binary-data-transmission system, operating at 1 kbaud over an h.f. channel, are presented. Error correction is effected by means of error detection and automatic request for repeat, via a feedback channel (a Post Office private line). A set of short, fixed-block-length cyclic codes is available, a code of appropriate redundancy being automatically selec... View full abstract»

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  • Zero-crossing preservation in the low-bit-rate pseudorandomly dithered quantisation of speech signals

    Publication Year: 1975, Page(s):119 - 123
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (730 KB)

    In earlier investigations, it has been found that, at low bit rates, the dithered quantisation of speech samples in pulse-code modulation (p.c.m.) is perceptually pleasing but is less intelligible than normal fixed-level quantised p.c.m. Also, it has been suggested that a possible cause of the reduced intelligibility of the dithered p.c.m. is the effect that the dithering has on the zero crossings... View full abstract»

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  • Two-dimensional computer analysis of a dielectric surface-loaded GaAs bulk element

    Publication Year: 1975, Page(s):124 - 130
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (800 KB)

    It is well established by experiment and theory that a travelling high-field domain in a GaAs bulk element is suppressed by surface loading of a dielectric material on the GaAs. To investigate this effect in more detail, a computer analysis based on a 2-dimensional model is performed. For the simulation, the full surface of a GaAs element of n = 5 × 1015cm¿3, L = 8.7 ¿m and d = 4.2 ¿m is loade... View full abstract»

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  • Geostationary-satellite earth coverage

    Publication Year: 1975, Page(s):131 - 134
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (542 KB)

    The basic problem considered is the relation of the shape of the beam of a geostationary satellite antenna to the area that it covers on the surface of the earth. It is envisaged that circular or elliptical beams may be used, but the beam is defined in general terms by a beam contour on a beam plane perpendicular to the beam axis by two angular co-ordinates ¿ and¿, while the earth contour in whi... View full abstract»

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  • Modified butterworth functions with low Q factor

    Publication Year: 1975, Page(s):135 - 136
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (281 KB)

    A method is given to determine the coefficients of a modified lowpass maximally flat (at the origin) Butterworth polynomial, with a reduced dominant-pole-pair Q factor at the expense of increasing order of the transfer function with multiplicity of the dominant pole pair greater than one. View full abstract»

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  • Hardware implementation of a recursive digital filter for m.t.i. radar

    Publication Year: 1975, Page(s):137 - 141
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (591 KB)

    The important features of the hardware implementation of a recursive digital filter for use with m.t.i. radar are described.The filter can operate with pulse widths of 0.8¿6 ¿s, over a wide range of pulse-repetition frequencies, and can handle up to 512 range bins in multiples of 8. It is programmable to realise a 1st-, 2nd- or 3rd-order Butterworth or Cheb¿shev frequency response, by simply en... View full abstract»

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  • Effect of numerical integration on the poles and zeros of a transfer function

    Publication Year: 1975, Page(s):142 - 144
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (395 KB)

    An expression for the transfer function of a numerical integrator is derived, and is illustrated by a mapping in the complex plane. Analysing a complete system using numerical integration is shown to be equivalent to displacing the poles and zeros of its transfer function. A simple graphical method for determining this displacement is described. The implicit Euler, trapezoidal and Shichman integra... View full abstract»

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  • Unified theory of cascade synthesis

    Publication Year: 1975
    IEEE is not the copyright holder of this material | PDF file iconPDF (150 KB)
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  • Part symmetrisation of 3-phase windings

    Publication Year: 1975, Page(s):145 - 148
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (475 KB)

    Polyphase symmetrisation has become a valuable technique in the design of pole-amplitude-modulated (p.a.m.) windings. Electrical unbalance in asymmetrical windings has been almost completely eliminated by its application. Difficulties have remained only in a few, but very important, special cases, such as in p.a.m. machines with very small numbers of slots per pole per phase. Part symmetrisation i... View full abstract»

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  • Axial magnetic forces in induction motors with skewed slots

    Publication Year: 1975, Page(s):149 - 153
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (566 KB)

    A comprehensive analysis of the axial force experienced by the rotor of an induction motor, as a function of slip, is presented. It is shown that the varying saturation along the stack of a skewed induction motor considerably affects the axial force due to skew. The calculated values obtained for the force are found to compare quite favourably with experimental results. It is also established that... View full abstract»

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  • Pole-change windings for linear induction motors

    Publication Year: 1975, Page(s):154 - 160
    Cited by:  Papers (7)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (791 KB)

    Pole-change techniques are potentially valuable for the speed control of linear induction motors. However, they are more difficult to apply in the linear case because of the nonuniform nature of the airgap flux. This precludes the use of parallel paths which are normally employed to reduce the complexity of the switching. The paper describes a new winding connection technique, and shows how it can... View full abstract»

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  • IEE Conference Publication 99. Electricity distribution: CIRED 1973. Part 2: Discussion

    Publication Year: 1975
    IEEE is not the copyright holder of this material | PDF file iconPDF (125 KB)
    Freely Available from IEEE
  • Transfer functions for variable-frequency induction motors with high-inertia loads

    Publication Year: 1975, Page(s):161 - 162
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (199 KB)

    A variable-speed induction motor is a nonlinear system, but, for small perturbations about an equilibrium point, it is approximately linear. For the case of ¿high¿-inertia loads a simplified approximate transfer function is proposed that relates speed variations to input-frequency variations. A method of determining the ¿high¿ criterion is suggested and computed. Predicted and measured results... View full abstract»

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  • D.C. dynamic braking of induction motors with secondary capacitors

    Publication Year: 1975, Page(s):163 - 164
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (232 KB)

    The presence of secondary-circuit capacitance permits large torque to be developed in induction motors at high speeds, with d.c. dynamic braking. Variation of braking torque at fixed speed can be achieved by variation of excitation current or capacitance, or by the inclusion of resistance in series or parallel with the capacitor. Test results are given for an experimental drive with a 3-phase woun... View full abstract»

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  • Induction-run performance of single-phase motors

    Publication Year: 1975, Page(s):165 - 167
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (406 KB)

    On a basis of the ¿exact¿ equivalent circuit of a single-phase induction motor operating on its main winding only, accurate solutions are obtained for (a) speed and torque at pullout,(b) speed and torque-gradient at zero torque, and (c) torque, current, power factor and efficiency at any speed. These are derived for a gap m.m.f. sinusoidally distributed and modified in a simple manner for the pr... View full abstract»

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  • Discussion on 'Distance-protection comparator with signal-dependent phase-angle criterion'

    Publication Year: 1975, Page(s):167 - 168
    IEEE is not the copyright holder of this material | PDF file iconPDF (336 KB)
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  • Some concepts involved in the analysis of the magnetic field in cage induction machines

    Publication Year: 1975, Page(s):169 - 175
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (919 KB)

    The precise meaning of terms widely used in the analysis of harmonic fields in the airgaps of rotating machines is examined. The available methods of analysis of induction-motor fields are compared, and a simplified approach to field harmonics involving the concept of modulation is outlined. The flux components observed at stator and rotor in a cage-rotor machine are classified, and their relative... View full abstract»

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  • IEE North Midland Centre: Chairman's address. The engineer in electricity distribution

    Publication Year: 1975, Page(s):175 - 176
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (319 KB)

    First Page of the Article
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  • Solution of the transmission-line equations for lossy conductors and imperfect earth

    Publication Year: 1975, Page(s):177 - 182
    Cited by:  Papers (10)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (880 KB)

    A numerically stable and efficient method of diagonalising the product of the per-unit-length impedance and admittance matrices for multiconductor transmission lines with lossy conductors or lossy earth return is presented. Cases are discussed where, by an approximation, the product of these matrices, which is complex and frequency-dependent, can be diagonalised using a real, frequency-independent... View full abstract»

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  • IEE Conference Publication 123. Power electronics: semiconductors and their applications

    Publication Year: 1975
    IEEE is not the copyright holder of this material | PDF file iconPDF (148 KB)
    Freely Available from IEEE
  • Optimal profiles of disc-type spacers for gas insulation

    Publication Year: 1975, Page(s):183 - 188
    Cited by:  Papers (5)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (835 KB)

    By adopting the suitable contact angle of a disc-type spacer, the surface flashover may be effectively suppressed on account of the decrease of the maximum field strength at the spacer surface. The calculation has clarified that the optimal contact angle of the spacer is 60¿70° according to the relative permittivity of the spacer for R2/R1 (ratio of inner and outer electrode radii) = 1/3, and th... View full abstract»

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  • Speed and torque control of a single-phase linear induction motor

    Publication Year: 1975, Page(s):188 - 189
    IEEE is not the copyright holder of this material | PDF file iconPDF (267 KB)
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  • New technique for quadrilateral distance relay

    Publication Year: 1975, Page(s):189 - 190
    IEEE is not the copyright holder of this material | PDF file iconPDF (198 KB)
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  • New superconducting switch: field-circuit version

    Publication Year: 1975, Page(s):191 - 192
    IEEE is not the copyright holder of this material | PDF file iconPDF (268 KB)
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  • Sufficient conditions for the nonoscillation of nonlinear pulse-controlled systems

    Publication Year: 1975, Page(s):193 - 196
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (521 KB)

    In this paper, the sufficient conditions for the absence of periodic modes for unforced nonlinear pulse-controlled feedback systems are given. These criteria relate to the behaviour of discrete nonlinear feedback systems within the Popov-Hurwitz sector, and the structurally similar in form to the well known circle and Popov criteria of the frequency domain, with the same simple graphical interpret... View full abstract»

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The Proceedings of the Institution of Electrical Engineers was published by the IET between 1963 and 1979.

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