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Electrical Engineers, Proceedings of the Institution of

Issue 11 • Date November 1973

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Displaying Results 1 - 25 of 38
  • Digital-summation threshold-logic gates: a new circuit element

    Publication Year: 1973 , Page(s): 1301 - 1307
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (805 KB)  

    Threshold-logic gates are memoryless, multiple-binary-input single-binary-output circuits that operate by an arithmetic summation process to determine the 0 or 1 gate output state. The availability of such gates would be of great advantage to digitial system design. A new approach to the circuit realisation of such gates is presented here, i.e. to use digital-summation techniques within the gate circuitry, as distinct from the analogue-summation techniques previously employed. The adoption of digital summation removes the former circuit-tolerance problems, and allows gates with great potential usefulness to be readily designed. View full abstract»

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  • Content-addressable memories based on magnetic-domain logic

    Publication Year: 1973 , Page(s): 1308 - 1314
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1041 KB)  

    The paper proposes the implementation of logic into magnetic-bubble memories, and particularly the realisation of a content-addressable data storage. The basic bubble-interactive logic and flip-flop functions are briefly reviewed. This is followed by the discussion of the most suitable memory structure and of the logical requirements for content addressing. Two cellular bubble logic-in-memory arrays and their operation modes are described in some detail. One employs successive, the other simultaneous, data access. A comparison between these two designs and a similarly structured random-access bubble memory device is given with special consideration for bit packaging density, interface terminals and data-access time. View full abstract»

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  • Variable-function logic circuit design with memory elements

    Publication Year: 1973 , Page(s): 1315 - 1320
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (697 KB)  

    A memory element such as a random-access (r.a.m.) may be used as a variable-logic device, the logic function being found between the address terminals and the output. This paper discusses design techniques whereby a single system of such memory elements may be used to implement several logic functions. The question of training or programming such systems is also considered with particular reference to cases in which the system is required to imitate another operational circuit. To this end a concept of `trainability¿ is introduced and it is shown that this is a nontrivial parameter that has to be taken into account at the design stage. Trainability tests are introduced and techniques for deriving training sequences for trainable systems are derived. View full abstract»

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  • Automated system for testing visual fields

    Publication Year: 1973 , Page(s): 1321 - 1327
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1093 KB)  

    An electronic system for automatically testing the human visual field is described in the context of mass screening for visual disorders, such as glaucoma. Present methods of field testing are briefly reviewed. The new system is patient operated and uses a television monitor as the means for presenting the test stimuli and displaying the results. A multilevel map of a patient's retinal sensitivity is produced in a form which is readily interpreted by an ophthalmologist. A data-transfer unit enables the local storage of results and allows direct access to a computer. Preliminary clinical trials show good agreement with conventional field-testing methods, and yield more detailed information than has hitherto been feasible on a routine basis. View full abstract»

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  • Linear-harmonic generation

    Publication Year: 1973 , Page(s): 1328 - 1330
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (407 KB)  

    A linear-harmonic generator is a nonlinear device in which an applied cosine wave of amplitude A causes some harmonic(s) of the input to be generated with amplitude(s) proportional to A. Such devices find application in phase-envelope processing in some types of modulation and speech-transmission systems. The present paper provides a theoretical study of the ability some characteristics have to generate linear harmonics. Linear-harmonic generation by single-valued characteristics which are representable by piecewise linearisation and those representable by a power series are investigated. It is shown that piecewise linear characteristics cannot generate linearly odd components. Also, it is shown that a characteristic expanded by a power series cannot generate linear harmonics, for either even or odd components. A particular single-valued characteristic, which precisely generates odd-harmonic components, is found, although it cannot be practically realised without approximation. View full abstract»

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  • Multiserver computer-controlled queuing system with pre-emptive priorities and feedback

    Publication Year: 1973 , Page(s): 1331 - 1336
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (601 KB)  

    The paper is concerned with the investigation of a multiserver computer-controlled queuing system with preemptive priorities and feedback. A formula for the generating function of the state probabilities of the system is derived and a method using the transition probabilities of a Markov chain for determining the first waiting-time distribution in the system is presented. View full abstract»

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  • Intermodulation interference in mobile multiple-transmission communication systems operating at high frequencies (3¿30 MHz)

    Publication Year: 1973 , Page(s): 1337 - 1344
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1150 KB)  

    Nonlinear responses in the transmitters, antennas and surroundings of a mobile multiple-transmission communication system give rise to intermodulation interference to the desired weaker signals at the receiver. The major sources of nonlinearity, for various transmitter configurations such as narrowband and wideband, have been identified. Laboratory-based experiments supporting the field trial work have investigated the nonlinear behaviour of ferromagnetic materials from the standpoint of surface preparation and chemical composition. Emphasis has been given to the shipborne environment. View full abstract»

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  • Synthesis of a fundamental cutset matrix

    Publication Year: 1973 , Page(s): 1345 - 1348
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (494 KB)  

    A simple and systematic procedure for the synthesis of a fundamental cutset matrix of a nonoriented graph is presented. The synthesis procedure is based on finding a cutset matrix Afs which has the property that a row in Afs corresponding to an incidence set has Vs nonzero entries where Vs corresponds to the number of rows in Afs. The method uses the results obtained by Mayeda and Iri. View full abstract»

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  • Measurements of the input admittance of thick spheroidal antennas in conductive mediums.

    Publication Year: 1973 , Page(s): 1349 - 1354
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (749 KB)  

    A measuring apparatus and experimental procedures have been developed to test the validity of a theoretically derived equivalent-circuit representation of the input admittance of prolate spheroidal antennas immersed in a general isotropic homogeneous medium. The experimental results reported are in excellent agreement with theoretical predictions and validate the possibility of computing antenna response by means of a very simple equivalent circuit. This is particularly important when the antenna is used for diagnostic purposes. With regard to the latter application, experiments have shown the opportunity of further investigations, both theoretical and experimental, especially to minimise the effect of the feeding connections on the antenna behaviour. View full abstract»

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  • Relationship between h.f. absorption at vertical and oblique incidence

    Publication Year: 1973 , Page(s): 1355 - 1361
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (835 KB)  

    Calculations are made of the absorption, in model ionospheres, by a phase-integral method, at vertical incidence and by 3-dimensional ray tracing at oblique incidence. The results are used to derive an empirical relationship for the variation of the absorption with path obliqueness, to an accuracy considered adequate for the prediction of the performance of h.f. communication circuits. The relationship takes into account both nondeviative and deviative absorption, and includes the effects of the Earth's magnetic field and is applicable to both E and F modes. It is shown to be more accurate than three other expressions currently in use. View full abstract»

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  • Modal analysis of triangular-cored glass-fibre waveguide

    Publication Year: 1973 , Page(s): 1362 - 1370
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1093 KB)  

    The modal analysis is given of a new optical glass-fibre waveguide configuration having a core with an equilateral triangular-shaped cross-section. Calculations are based on the point-matching method, which is known to be inaccurate if sharp corners exist in the boundary geometry. In view of this, two numerical methods are derived to check and correct the resulting eigenvalues and their fields. These new methods involve, respectively, a varia-tional formula and a harmonic-correction integral. A comparison of computations shows that the lower-order point-matched eigenvalue solutions are sufficiently accurate for the constraints laid down by manufacturing tolerances, and apart from regions near to the dielectric interface, the field plots require only a small correction. Close to the apexes, however, the mathematically exact correction procedure also becomes numerically unstable. Modal charts, field and power-density plots, and estimates of cladding field leakage, are given, and degenerate modes and symmetry properties are discussed. Experimental data available confirm the usefulness of the analysis, and it is concluded that the new triangular-cored guide may be operated in a very similar manner to the circular-cored monomode fibre. View full abstract»

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  • Propagation behaviour of cylindrical-dielectric-rod waveguides

    Publication Year: 1973 , Page(s): 1371 - 1378
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (911 KB)  

    The exact propagation behaviour is considered of cylindrical dielectric waveguides possessing a central core of higher permittivity than the surrounding cladding. Results are compared with those obtained by making the coremode and cladding-mode approximations. The former approximation is found to be valid for most purposes; the latter is much more restricted. Although the waveguide parameters chosen are representative of monomode optical waveguides, the results should find wider application. View full abstract»

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  • Digital-computer-simulation results of multistage delta-modulation systems

    Publication Year: 1973 , Page(s): 1379 - 1382
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Digital-computer-simulation results of multistage delta-modulation systems are reported. Considerable improvement in the tradeoff between signal/noise ratio and transmission rate is possible. Results for 2- and 3-stage systems with band-limited flat spectrum and RC-integrated spectrum are given. Significant decrease in the idle-channel noise of the first stage is possible with the help of the second stage in a 2-stage coder. View full abstract»

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  • New approach to m.t.i. clutter locking

    Publication Year: 1973 , Page(s): 1383 - 1390
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (975 KB)  

    Proposals are made for new techniques, for clutter locking in m.t.i. radar systems, that adapt automatically to rapid variations in the clutter bias velocity with range. The proposed schemes are based upon what is believed to be the novel principle of correcting for the clutter bias velocity after the radar returns have been read-out from the vector canceller stores and demand no additional storage. The basic arrangements have been analysed in detail and procedures have been established with which to design systems to meet specified performances. An analysis based on generalised symmetric and skew clutter spectra has shown that the performances of these systems are very little affected by the shape of the spectrum. Using these procedures, a design has been derived for a clutter-locking arrangement for a pulse-staggering radar in which the mean Doppler frequency of the clutter can rise to 30% of the p.r.f. Addition of the proposed clutter-locking arrangement is expected to give an overall improvement factor which will be better than 23 dB at all Doppler shifts, and when averaged over all shifts will be 25 dB. In order to confirm the design analysis and to establish the degree of smoothing required in range, a program was written to simulate this particular design and to inject noiselike clutter having either a Gaussian or a highly skew spectrum. The results of this simulation corresponded satisfactorily with the predicted performance and yielded the result that the range smoothing required corresponded to only 4 range cells. The design awaits experimental verification. View full abstract»

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  • IEE Conference Publication 105. Raderߝpresent and future

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (172 KB)  
    Freely Available from IEEE
  • IEE Conference Publication 106. Digital instrumentation

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (86 KB)  
    Freely Available from IEEE
  • Method of predicting transient-current patterns in transformers

    Publication Year: 1973 , Page(s): 1393 - 1396
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The paper describes a method for analysing the transient behaviour of a transformer, taking into account the mutua-coupling between phases and the nonlinearity of the magnetic material. A 3-phase, 3-limb transformer is taken as the basis for illustrating the theoretical analysis, but the method can be applied to any electromagnetic configuration. A selection of calculated and experimental results are presented, illustrating the accuracy achieved in both magnitude and waveform. View full abstract»

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  • Arc-quenching transients in h.v. d.c. convertors

    Publication Year: 1973 , Page(s): 1397 - 1402
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (683 KB)  

    A mathematical model is described suitable to analyse the transient response of present-day h.v. d.c. convertor stations to arc-quenching disturbances in the main valves and bypass valves. The model is used to determine the voltage stresses at the convertor plant and the effect of valve restrike following the disturbance. View full abstract»

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  • Topological approach to thyristor-circuit analysis

    Publication Year: 1973 , Page(s): 1403 - 1405
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (303 KB)  

    In the thyristor-circuit analysis, the open-circuit branches are removed from the associated graph to formulate the modified incidence matrix. An algorithm for the formulation of incidence matrix is presented. On the basis of a normal tree, the state equations are derived. As the open-circuit branches are removed from the graph, the usual problem of widely varying time constants associated with the digital computation of the thyristor circuits is completely eliminated. Necessary on-switch-current and off-switch-voltage equations required for the device logic modules are derived. The method is illustrated with an example. View full abstract»

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  • Selection of p.v.c.-insulated cables for 415 V motors in CEGB power stations

    Publication Year: 1973 , Page(s): 1406 - 1413
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (976 KB)  

    The choice of size of power cables for connections between power-station auxiliary motors and associated starters invariably has to be made before precise information on the cable environment and type of drive is available. The paper analyses the various factors that govern the selection of these cables, and offers a synthetic solution to the problem for all conditions normally encountered, so that for a given duty and route length the necessary cables may be scheduled in advance of the final operating data. Each rating of squirrel-cage motor with direct-to-line starting is considered in conjunction with cable characteristics, circuit parameters, switchgear, protection, earthing, environment and economics. The paper concludes with a recommended range of p.v.c.-insulated cable sizes for each motor rating to meet normal conditions. View full abstract»

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  • Discussion on ¿Asynchronous starting of synchronous machines with or without rectifiers in the field circuit¿

    Publication Year: 1973 , Page(s): 1414 - 1416
    Save to Project icon | PDF file iconPDF (575 KB)  
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  • Discussion on ¿Short-line fault tests on the CEGB 275 kV system¿

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (177 KB)  
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  • Response of an optimally controlled d.c. transmission system

    Publication Year: 1973 , Page(s): 1418 - 1419
    Save to Project icon | PDF file iconPDF (183 KB)  
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  • Reduced-gradient method for economic dispatch

    Publication Year: 1973 , Page(s): 1419 - 1420
    Save to Project icon | PDF file iconPDF (217 KB)  
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  • Erratum: Moisture control of cable environment with particular reference to surface troughs

    Publication Year: 1973
    Save to Project icon | PDF file iconPDF (105 KB)  
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Aims & Scope

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

Full Aims & Scope