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Electrical Engineers, Proceedings of the Institution of

Issue 2 • Date February 1973

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Displaying Results 1 - 25 of 32
  • Determination of vocal-tract-area function from transfer impedance

    Publication Year: 1973 , Page(s): 153 - 158
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (845 KB)  

    A procedure is described for calculating the cross-sectional area of the vocal tract from the magnitude of its transfer impedance when the lips are resistively terminated. The process is noniterative and 5 kHz of line spectrum with normal-pitch frequency spacing contains sufficient information for the synthesis to be performed. The synthetised area functions are unique, and are good approximations to smoothed versions of the actual area functions. Area-function data of Fant are used to test the procedure. View full abstract»

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  • Radiometer measurements of atmospheric attenuation at 19 and 37 GHz along Sun-Earth paths

    Publication Year: 1973 , Page(s): 159 - 164
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (675 KB)  

    The measurements of attenuation described in the paper refer to data recorded over a 3-year period at a frequency of 19 GHz, and over a 1-year period at 37 GHz. The relevance of these data to Earth-space communication links is discussed. Statistics showing the percentage of observation time for which the attenuation exceeds various values are given for each year for various ranges of elevation angle. At 19 GHz, the values of attenuation obtained from the extreme annual distributions differ by a factor of about two at a given percentage of time. Also, the percentage of time for which the attenuation at 19 GHz exceeded 10 dB for the `worst¿ month is an order of magnitude larger than the corresponding value for the 3-year period. Statistics derived from data obtained during periods of common observation at 19 and 37 GHz are compared for various ranges of elevation angle. Histograms showing the number of fades as a function of the duration of the fade are presented for both frequencies for fades greater than 5 and 10 dB, and a comparison of the instantaneous values of attenuation at 19 and 37 GHz at fade maxima has been made. View full abstract»

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  • Transhorizon propagation on v.h.f. and u.h.f. radio links in the United Kingdom

    Publication Year: 1973 , Page(s): 165 - 172
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (756 KB)  

    An analysis has been made of v.h.f. and u.h.f. transmission data on 65 overland links of up to 400 km in length in the United Kingdom. The analysis reveals that the field strength exceeded for 1% of the time is significantly greater than that predicted by CCIR recommendation 370-1, especially for band III (150¿250 MHz), but also to some extent for band I (41.68 MHz). A detailed analysis is made of several transmission links in which the factors distance, antenna height, terrain irregularities and meteorological condition were very similar, but the operating frequencies were different. The results of the detailed analysis are interpreted in terms of reflection theory using a 4-ray model. The layer heights at which partial reflection gives enhancements of band-III transmissions similar to those observed experimentally are found to correspond approximately to atmospheric layers of maximum lapse rate of refractive index, as computed from meteorological-radiosonde observations. View full abstract»

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  • Transmission loss at high frequencies on 3260 km temperate-latitude path

    Publication Year: 1973 , Page(s): 173 - 180
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1124 KB)  

    Measurements of the pulse modal patterns and received-signal strengths were made at frequencies of 9.9, 17.5 and 23.0 MHz over a 3260 km path from Akrotiri, Cyprus to Slough, England for 12 months during 1968¿69 at sunspot maximum. The principal modes of propagation involved one and two reflections from the F2 layer. The oblique-path ionospheric absorptions are estimated from the signal-strength data by allowing for all other transmission-loss factors. The absorptions so deduced are compared with those given by various published formulas. View full abstract»

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  • Scattering by perfectly conducting rotational bodies of arbitrary form excited by an obliquely incident plane wave or by a linear antenna

    Publication Year: 1973 , Page(s): 181 - 182
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (261 KB)  

    An algorithm based on the rigorous spherical-wave-expansion method is developed that is capable of treating rotational bodies excited by an obliquely incident plane wave or a thin linear antenna. The algorithm is used to compute the scattering behaviour of various rotational objects, such as cone-spheres, discs, finite cylinders, spheroids and some other shapes. View full abstract»

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  • Near-field technique for inferring aperture antenna radiation patterns

    Publication Year: 1973 , Page(s): 183 - 185
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (357 KB)  

    The method of Brown and Jull for inferring the far field from the near field has been extended to arbitrary antennas, with measurements made in one plane only. The primary concern has been with aperture antennas. The theory of the computational reduction of the measured data has been obtained. The results of a practical application of this near-field technique (n.f.t.) to a circular-waveguide-aperture antenna are described. The modal distribution in the waveguide aperture is estimated. This distribution has been substituted into a variational expression for the waveguide admittance. The result is close to the measured value, thereby confirming the accuracy of the n.f.t. View full abstract»

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  • Microwave data link for computer communication

    Publication Year: 1973 , Page(s): 186 - 190
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    An experiment is described in linking to a large digital computer at data rates in the order of 107 bit/s. The system is based on standard British Post Office microwave equipment and well established high-speed wire links; the interface between the two sections uses the CAMAC-system convention. The total system is described, and details are given of some of the equipment not previously published. Important features of the system are the termination of both ends of the link in a high-level-language module (in this case PL1), executing in a multiprogramming operating system, and corrected error rates better than 1 bit in 109. View full abstract»

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  • Application of time-series algebra to the adaptive equalisation of band-limited waveform-transmission systems

    Publication Year: 1973 , Page(s): 191 - 196
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (861 KB)  

    Using time-series algebra, the operation of adaptive equalisers for both minimum-mean-signal-error and minimum-mean-square-error criteria are considered, and the convergence properties of the iterative procedures generally used are discussed. It is pointed out that, in any practical situation, the control criterion and the iterative algorithm to be used, must be selected to provide the desired performance over the range of situations likely to be encountered. The effect of the equaliser on the regenerator-input signal/noise ratio is also considered, and this, together with the economic need to minimise the equaliser length, is shown to lead to a requirement to select the reference sampling point accordingly. One selection algorithm is described, and its operation is demonstrated in an example. View full abstract»

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  • Millimetre-wave generator that uses a spiralling electron beam

    Publication Year: 1973 , Page(s): 197 - 205
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1249 KB)  

    A millimetre-wave generator that uses a helical electron beam spiralling around the axis of a nearly square wave-guide is described. The frequency of gyration round the axis is made equal to one-half of the signal frequency, thus halving the longitudinal magnetic field by comparison with those of cyclotron devices. Power outputs in excess of 2W at Q band wavelengths have been achieved with low-current, high-voltage beams, but the most important feature of the device is that the same electro-optical system can be used at considerably shorter wavelengths, for example ¿ = 2 mm. A brief historical introduction describes the development of this tube in relation to the better known cyclotron tubes. View full abstract»

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  • Precision hardware circular-arc generation for computer graphic-display systems using line-segment-data

    Publication Year: 1973 , Page(s): 206 - 212
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (819 KB)  

    For advanced graphics, it is required that both general and circular functions should be displayed, in addition to alphanumeric and line diagrams. For general functions, software is used, owing to the low frequency of occurrence of general functions on display diagrams. For circular functions, this is not the case, and there is a need for hardware generation with scaling, windowing and scissoring properties. Further, for precision, the circular arc should start and finish exactly on the m × m screen matrix, with points on the drawn arc within one increment of the true arc. This paper describes the generation of arcs by hardware, using successive line-segment data that satisfy the error equations. These errors are derived, and a computer simulation of the hardware logic design is used to analyse the errors and to determine the bit redundancy in the ¿¿2/2 registers. The final design is capable of generating circular arcs within the prescribed error limits at high generation speeds. The generator may be included in any display system that possesses accurate line-drawing facilities. View full abstract»

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  • Computer technique for solving 3-dimensional electron-optics and capacitance problems

    Publication Year: 1973 , Page(s): 213 - 220
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (911 KB)  

    Electron-optics problems involving planar and axial symmetry are frequently analysed by using iterative procedures to solve Laplace's equation within a specified boundary. The computation time and storage requirement for these procedures may be prohibitive when it is necessary to extend the analysis to three dimensions for problems involving asymmetric fields. An alternative approach is described, known as the method of moments, which does not use an iterative method, but calculates the field directly from the charges induced on the electrodes by the excitation potentials. This technique provides a further facility, which permits the capacitances between arbitrary 3-dimensional electrodes to be obtained. The basic theory and operation of a computer program which employs this method are described. As a practical application, the program has been used to investigate the electron-optical properties of a mesh with rectangular apertures. View full abstract»

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  • IEE Western Centre Electronics & Control Section: Chairman's address. Electrical aspects of aircraft control

    Publication Year: 1973
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (114 KB)  

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  • Feasibility of turbogenerator with superconducting rotor and conventional stator

    Publication Year: 1973 , Page(s): 221 - 227
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (914 KB)  

    In a 660 MW turbogenerator, the losses associated with the rotor total some 4.5 MW, mainly due to direct current in the field winding. The feasibility of saving this by making the winding superconducting is examined. The stator coils carry alternating current, and so they cannot be made superconducting, and, in the concept proposed here, the stator is substantially conventional. The new rotor has no iron, except for shaft ends, and the winding is embedded in an insulating cylinder cooled with liquid helium from a refrigeration plant. The winding is protected from harmful a.c. fields by a copper cylinder which rotates with it. The gap is evacuated, and this screening cylinder is kept cold by thermal conduction in the residual gas to a stationary low-temperature shield. The machine has high steady-state-and transient-stability margins, and the need for rapid field changes is greatly diminished The new rotor allows the present stator to be uprated. The economic advantage of the machine, taking refrigeration into account, depends on the degree of uprating found possible, and is in the range £290 000¿£830 000 for an output range of 660¿1000 MW. Many problems, particularly of a mechanical nature, remain to be solved, but none appears insuperable. View full abstract»

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  • Open-circuit voltage decay of a turbogenerator

    Publication Year: 1973 , Page(s): 228 - 232
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (597 KB)  

    The decay of terminal voltage of an unexcited turbogenerator, following its disconnection from the a.c. busbars, is determined analytically. It is shown that, because of eddy current in the solid rotor, an infinite number of exponential-decay terms are required to describe the voltage decay. Results obtained theoretically are compared with those of tests carried out by the Central Electricity Generating Board at Northfleet, and good agreement is obtained. Of particular interest are the large quadrature-axis time constants evident in both theoretical and experimental studies. View full abstract»

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  • IEE Mersey & North Wales Power Section: Chairman's address. Switchgear progression

    Publication Year: 1973
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (118 KB)  

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  • Improvement of turbogenerator transient performance by control means

    Publication Year: 1973 , Page(s): 233 - 240
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (861 KB)  

    The availability of electric governors and the provision for continuous control over the turbine interceptor valves, in addition to the high-pressure-steam valves, present a readily controllable, fast-response turbine-power-output system. This paper looks at the capability of such a system for improving turbogenerator transient performance for both large and small disturbances. The performance capabilities of excitation control are also considered for comparison. View full abstract»

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  • New temperature test for synchronous machines

    Publication Year: 1973 , Page(s): 241 - 242
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    A novel temperature-test method for synchronous machines is described. The test machine is operated either as a motor at no load or as a generator supplying a reactive load, both with rated field excitation, while a second source is applied to cause full r.m.s. current to circulate in the armature winding. The test simulates a true temperature test in every respect, and is of special value for machines rated at power factors above 0.9. The new test may additionally be used to determine the machine efficiency at rated load. View full abstract»

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  • Simplified universal-commutator electric motor

    Publication Year: 1973 , Page(s): 243 - 244
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (271 KB)  

    The paper presents a universal-commutator motor of less than 1 kW power, the construction of which is different from that of the classical motor, both in the winding and in the lamination positions. The performances of experimental models and the economical advantages of this type of motor are presented. View full abstract»

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  • Power-factor compensation of thyristor-controlled single-phase load

    Publication Year: 1973 , Page(s): 245 - 246
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    It is found that an effective way to obtain a, good power factor with a thyristor-controlled load is to use a parallel-connected uncontrolled resistive load of similar rating. The use of parallel-connected capacitance alone gives no significant degree of power-factor improvement, even when the capacitance is adjusted to the optimum value for each step of thyristor firing angle. View full abstract»

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  • Improvement of power-system transient stability by phase-shift insertion

    Publication Year: 1973 , Page(s): 247 - 252
    Cited by:  Papers (15)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    Computational studies of the transient stability of a synchronous machine connected to an infinite busbar by a double-circuit transmission line are used to illustrate the effect of relative phase-shift insertion between the machine and its associated power system. This method of obtaining a change in the effective rotor-excitation angle, and thereby the power transfer, is described, together with an outline of possible methods of implementation by a phase-shifting transformer in a power system. View full abstract»

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  • IEE North-Western Utilisation Section: Chairman's address. Less and less about more and more¿some aspects of utilisation engineering

    Publication Year: 1973
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (127 KB)  

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  • Erratum: Safety of household electrical appliances

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (127 KB)  
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  • Transient analysis of underground power-transmission systems. System-model and wave-propagation characteristics

    Publication Year: 1973 , Page(s): 253 - 260
    Cited by:  Papers (123)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (942 KB)  

    A mathematical model suitable for the analysis of travelling-wave phenomena in underground power-transmission systems is presented. The model is developed in terms of a generalised angular frequency, and may therefore be applied to the solution of steady-state problems or, by means of Fourier-transform techniques, to the solution of transient problems. The model takes into account skin effect in the conductors and in the soil. It is then shown how the system model may be analysed using multiconductor-transmission-line theory to give the transient response of the cable system. The wave-propagation characteristics are given for the natural modes of a certain cable system. These characteristics are examined with a view to their implications on transient phenomena. View full abstract»

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  • Optical technique for measurement of current at high voltage

    Publication Year: 1973 , Page(s): 261 - 267
    Cited by:  Papers (14)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (973 KB)  

    Consideration is given to the design of an optical device for the measurement of current at high voltage based on the Faraday magneto-optic effect in flint glass. A laser beam directed upward from the ground passes through the free atmosphere to interrogate a passive transducer situated on the high-voltage line. The beam is then reflected down to a ground-based detector system. The investigation has been directed, in the first instance, towards the provision of a versatile research tool for the analysis of disturbed-line conditions, although, ultimately, such an arrangement could obviate the necessity for the expensive and bulky insulation found in conventional current transformers. This is particularly relevant in view of the trend towards higher transmission voltages. The appropriate design features are considered in some detail. Their implementation in a prototype device is also considered. The bandwidth of the prototype device was from direct current to 2 MHz, and its dynamic range for less than 5% nonlinearity was 10¿12000 A (these figures are not fundamental and can be varied). The device promises to provide a cheap, accurate and robust current-measurement system for various applications in power-transmission networks. View full abstract»

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  • IEE Western Power Section: Chairman's address. A century of overvoltages

    Publication Year: 1973
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (113 KB)  

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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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