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Electrical Engineers, Proceedings of the Institution of

Issue 1 • Date January 1969

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Displaying Results 1 - 25 of 38
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  • Development, design and test procedures for random generators using chaincodes

    Page(s): 22 - 26
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (646 KB)  

    The paper considers the development, design and test procedures for a range of random-pulse generators which exploit the properties of chaincodes. While the generators were developed for simulation of road-traffic situations, they have wide applications in the simulation of the central processors of digital computers and the testing of digital control systems. The generators operate at high speed in a parallel fashion. They require only a very limited number of logical elements, and output-pulse patterns may be repeated starting at any point. View full abstract»

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  • Evaluation of performance of random generators employing chaincodes

    Page(s): 27 - 34
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (900 KB)  

    The objective of this paper is to contrast random generators built by Redshaw and Robinson with simpler generators devised by the author. The test procedures laid down in an earlier paper are followed. Both types of random generator were designed for the simulation of random arrivals of vehicles at road-traffic intersections. There is, however, a wide variety of other applications for such generators. These include message-switching simulation, and the simulation of the operation of the central processor of a multiprogram computer. The tests performed indicated that both classes of generator satisfied criteria for randomness, provided that care was exercised at the design stage. View full abstract»

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  • Transistor-feedback-amplifier stabilisation using admittance measurements

    Page(s): 35 - 42
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (893 KB)  

    A method is described for stabilising a single-loop negative-feedback transistor amplifier based on measurements of a chosen short-circuit-stable closed-loop driving-point admittance between two terminals within the amplifier. A correcting network is synthetised, the admittance of which, when added to the measured admittance, prevents zero encirclement by the locus of the total admittance by an adequate margin. Formulas are given enabling margins against zero encirclement to be interpreted in terms of movements of corner frequencies associated with a frequently used internal amplifier configuration. The method is demonstrated to be straightforward for an amplifier requiring measurements up to 20MHz, and the admittance margins obtained are compared with margins obtained from loop-gain measurements. View full abstract»

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  • Analysis of the statistics and threshold of the phase-lock loop

    Page(s): 43 - 52
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1190 KB)  

    The mean-square value of the phase error in the phase-lock loop is determined from the linear differential equation. Conditions are then derived, for its minimisation, with an integral plus proportional filter in the loop, for an input consisting of an f.m. f.d.m. carrier plus thermal noise. The statistics of the phase error are then deduced using the Fokker-Planck technique for an arbitrary loop filter. From the statistics, the loss of lock rate is derived and each loss of lock is assumed to produce an inpulse in the baseband. The well known result of Rice is used to determine the output signal/noise ratio, and the point of threshold arising from the loss of lock is shown. View full abstract»

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  • Bandpass LC filters having prescribed amplitude and nearly constant group-delay characteristics

    Page(s): 53 - 58
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (830 KB)  

    The paper describes the synthesis of arithmetically symmetrical, broadband LC filters having prescribed amplitude response and nearly constant group delay, with particular reference to i.f. filters for radio-relay systems. These filters must suppress unwanted signals, particularly the adjacent carrier frequencies, without significantly distorting the required signal. For low distortion, the filters must have both flat amplitude and constant group-delay responses over the passband centre. Filters synthetised for 1800- and 960-channel systems have satisfied these requirements, the transfer-function design and measured characteristics of the filter for the 960-channel system being given as an example. The filters have the advantages that they can be inserted in the i.f. chain without the need for further phase equalisation, and that they give improved amplitude responses compared with conventional filter and equaliser combinations. View full abstract»

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  • Transformed hypergeometric transmission lines

    Page(s): 59 - 64
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (554 KB)  

    A transformation procedure is described for determining a set of nonautonomic distributions which are complementary to previously described general classes of lines. A table of these distributions is presented, together with the conditions necessary for their evaluation. In particular, for the Gaussian distributed RC line, which is inherent, for example, in some diffused-semiconductor realisations, a solution is obtained in terms of a convergent confluent hypergeometric series which is equivalent to an earlier solution in terms of Hermite polynomials. Finally, its performance is evaluated and experimentally compared with a well known distribution. View full abstract»

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  • Driving-point-function synthesis using nonuniform lines

    Page(s): 65 - 70
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    Necessary and sufficient conditions for the synthesis of a driving-point function using any two kinds of one-port impedances are presented, and the result is used to develop a procedure for synthetising a driving-point function using tapered lines. The result also provides a short proof for O'Shea's necessary and sufficient conditions for the realisation of a driving-point function using symmetric structures. It is shown that any impedance which can be realised using symmetric lines may always be realised using the one-port impedances of the nonuniform transmission lines used in the construction of the symmetric lines. It is shown that all the existing synthesis procedures for the realisation of a driving-point function using any two one-port impedances are special cases of the general procedure advanced in this paper. Necessary and sufficient conditions for realising a driving-point function as a cascade of symmetric structures have been advanced. These are shown to be equivalent to those for realising the same driving-point function using the open- and short-circuit impedances of a symmetric structure. A procedure for such a cascade synthesis is advanced. If the structure is a uniform line, it provides a simple alternative to Wyndrum's cascade-synthesis procedure. An illustrative example is also included. By using known transformations, all the results may be applied to other types of lines such as lossless lines. View full abstract»

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  • Wedge-diffraction functions and their use in quasioptics

    Page(s): 71 - 76
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (681 KB)  

    Asymptotic and other formulas are derived ab initio for the field diffracted by a perfectly conducting wedge when illuminated by a line source. In the transition zone between lit and shadowed regions, the field is decomposed into image and diffraction terms which enable the formulas to be used throughout the region for self-consistent field analyses. The wedge-diffraction functions are finding a growing application in the investigation of electromagnetic problems in which the dimensions are too large for waveguide-mode analysis, but too small for geometric optics to apply. Various formulas are scattered throughout the literature. In this paper, they are derived from first principles and presented in a form in which the areas of use are indicated, and the important transition zone near a shadow boundary is explained in some detail. View full abstract»

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  • Representation of noise sources in pumped nonlinear systems

    Page(s): 77 - 83
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (683 KB)  

    Several different methods have been used to represent physical sources of noise at a frequency ¿0 in a linear 2-port network, and this representation usually simplifies the analysis of propagation of noise through the network when it is connected to another network or a set of networks. It is shown that similar methods can be used to represent physical sources of noise in a nonlinear network when it is pumped by a strong signal and when the noise sources present in the system are small. In such a case, the device acts as a linear system to the noise and the terminal noise components are linearly related. This kind of representation simplifies the noise analysis of such systems and enables us to investigate how the noise propagates through the system. It will be shown that, at each port, for each frequency ¿0 present in the system, it is necessary to have two equivalent noise sources rather than the one that is required in circuit theory of linear noisy networks. View full abstract»

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  • Inhomogeneous dielectric filling to simulate curvature in model Earth-ionosphere waveguide

    Page(s): 84 - 86
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    A careful study of the variation of the permittivity of synthetic foam materials under compression has led to a physically realisable solution to the problem of synthetising an inhomogeneous medium of propagation used to simulate curvature artificially in a microwave model of the Earth-ionosphere waveguide. View full abstract»

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  • Single-phase autoreclosure of extra-high-voltage transmission lines. An investigation into the residual fault current and recovery voltage

    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (631 KB)  

    The success of single-phase autoreclosure of extra-high-voltage transmission lines is based on the possibility of self extinction of the secondary arc, in spite of the influence of the sound phases. The residual fault current and the recovery voltage of the switched phase are among the most essential factors affecting self extinction of the residual fault. In this paper, a method is developed for the calculation of the recovery voltage and residual fault current during single-pole switching. The power system investigated consists of a remote power station interconnected to a large electrical system, through a single-circuit extra-high-voltage transmission line. The analysis includes the effect of fault location, line length, station parameters, transmission-line loading and the electromechanical swing subsequent to fault occurrence. The effects of the above factors on recovery voltage and residual current are investigated on the basis of numerical computations for a 500 kV transmission system. View full abstract»

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  • Calculation of steady-state temperature rise of water-cooled buried cables using a new iterative method

    Page(s): 101 - 106
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (763 KB)  

    The paper describes a new iterative method for calculating the steady-state temperature rise of water-cooled cables buried in a homogeneous soil. Cables and water pipes are represented by line heat sources and sinks of variable magnitude and position, and a computer program is used to calculate the necessary magnitudes and positions of the heat sources and sinks needed to represent the temperature distribution accurately. Open boundaries are used, and this avoids possible errors resulting from the usual practice of imposing isothermal surfaces at finite distances from the cables. It allows a check to be made on boundary conditions used for relaxation calculations or electrolytic-tank measurements. However, the method of analysis described here is considered superior to relaxation for calculating cable temperature rise in a homogeneous soil. A detailed example is given of a calculation carried out at one point in a cable run, including the complete temperature distribution in the soil. A technique is then outlined for applying the method at various points along a cable run, and consequently for calculating the rate of water flow required to maintain an acceptable conductor temperature. View full abstract»

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  • Divided-winding-rotor synchronous generator. A comparison of simulated 30 MW conventional- and divided-winding-rotor turbogenerators

    Page(s): 113 - 126
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1473 KB)  

    Experiment with a 5kVA machine showed the feasibility of a new form of turbogenerator using a rotor winding of two sections, in X formation, controlling the torque and reactive requirements separately. The performance of a conventionally wound rotor turbogenerator (c.w.r.) of 30MW size, described by Shackshaft, is compared with that of a divided-winding-rotor (d.w.r.) arrangement (CEGB patent application 2240/65) of the same machine. The analogue simulation shows that the d.w.r. can control power and reactive output satisfactorily, without altering the rotor position in relation to the generator air-gap flux. Fully rated stator current at leading power factor can be obtained continuously from no load to full load. The speed of response of the d.w.r.-generator reactive power to a step change of infinite-busbar voltage is, on average, twice that of the c.w.r. Turbogenerator stability is improved, and is shown to be independent of reactive generation or absorption, being affected only by active-power generation. Transient-stability comparisons are made by simulating 3-phase short-circuit faults close up to the high-voltage busbar, with low- and high-impedance connections to the infinite busbar. The c.w.r. simulation at full load with full excitation withstands a fault duration of 0.45s, which comes down, with reducing excitation, to 0.32s when Qu = ¿ 0.225 p.u. and rotor angle = 70°; 0.2s when Qu = ¿ 0.6 p.u. and rotor angle = 100°; and less than 0.1 s when Qu = ¿ 0.9 p.u. and rotor angle = 120°. Comparable d.w.r. simulation of load and excitation conditions all require a fault duration exceeding 0.4s to cause instability. Even the Qu = ¿ 2.3 p.u. condition is simulated without deterioration of control, and requires 0.4s fault duration to cause instability. The high-impedance connection to the infinite-busbar simulation shows, in general, that the maximum fault duration for each type of generator is reduced by 0.1s. View full abstract»

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  • Current distribution in sheet- and foil-wound transformers

    Page(s): 127 - 129
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (303 KB)  

    In foil-wound transformers, the width of the foil used in one winding is generally the full winding height of the transformer so that the current density is nonuniform. A mathematical model is set up for such transformers, and the current density is obtained as the solution to an integral equation. A method of solution suitable for use on a digital computer is outlined. View full abstract»

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Aims & Scope

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

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