Proceedings of the IEE  Part C: Monographs
Volume 108, Issue 14, September 1961
Volumes & issues:
Volume 108, Issue 14
September 1961
Interconnected rotor induction motors
 Author(s): N.C. Enslin
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 281 –286
 DOI: 10.1049/pic.1961.0038
 Type: Article
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The stators of two identical woundrotor induction motors are connected to a common supply to produce fields revolving in the same direction. The shafts are coupled mechanically and the rotor circuits are electrically connected together with the voltages initially phased so that no rotor current flows. By rotating one stator relative to the other through an angle β the rotor voltages are no longer in antiphase, rotor currents flow and the unit produces torque.Boucherot adopted a similar scheme in the construction of a composite machine with two stators and a common squirrelcage rotor. The midpoints of the rotor bars were connected together through a resistive element so that currents always flowed in the rotor circuits and zero torque could not be obtained.Expressions for torque are derived for the shuntinterconnected rotor developed by Boucherot and for the purely seriesinterconnected motor investigated by the author. It is shown that, for the former, torque cannot be controlled from zero without voltage variation, whereas in the latter arrangement zero torque is always obtained when the phases of the induced rotor voltages are in opposition.The properties and applications of the series interconnected motor circuit are discussed. By the insertion of impedance the torque/speed characteristics of the motors can be modified retaining the zero torque position. Possible applications include small hoists, cranes or lifts, and positioning, manipulating or tensioning drives for which precise control is required.
Frequency response of feedback relay amplifiers
 Author(s): Ze'ev Bonenn
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 287 –295
 DOI: 10.1049/pic.1961.0039
 Type: Article
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The frequency response of feedback relay amplifiers is analysed by the dualinput describingfunction method. At low signal frequencies, the amplifier behaves like a saturating linear amplifier. This picture is modified at higher frequencies, owing to synchronous effects, and it is difficult to achieve satisfactory operation when the ratio of the inputsignal frequency to the periodic excitation frequency is appreciable. To eliminate synchronous effects within the signal band, restrictions must be imposed on the forward lineartransfer function. The theory is compared with an experimental example.
Sign matrices and realizability of conductance matrices
 Author(s): G. Biorci
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 296 –299
 DOI: 10.1049/pic.1961.0040
 Type: Article
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Given a conductance matrix G of order n, the problem of realizing it by a network with n + 1 nodes can be split in two parts: to find the tree of the ports corresponding to the given matrix G; and to determine the actual resistances of the branches of the network.A procedure to solve the first (topological) problem is proposed, which is simply concerned with the signs of the elements of the given matrix G. The successful development of the procedure can be considered as a necessary and sufficient condition for the existence of a tree corresponding to G.
Travellingwave analysis of generalized networks
 Author(s): J. Zawels
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 300 –308
 DOI: 10.1049/pic.1961.0041
 Type: Article
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The behaviour of networks, whether lumped, distributed, active or passive, is analysed from a fundamental travellingwave point of view. Generalized wave parameters are derived for a 2port network from which image, conjugate and iterative parameters follow as special cases. The relationship of these to short and opencircuit parameters are also given.A matrix organization of waves in a multiport network is next presented, which distinguishes between waves internal and external to the network. Through special transformations, voltage and powergain matrices are derived and their relationship to the conventional scattering matrix is shown.Finally, a visual representation of the wave trains set up in cascaded stages is given in the form of wave flow diagrams, reminiscent of Mason's feedback graphs.
Optimum sampleddata control
 Author(s): R. Jackson
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 309 –316
 DOI: 10.1049/pic.1961.0042
 Type: Article
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A method of rendering feedback control systems amenable to treatment by the Wiener theory is applied to the case in which the controller operates on a sampled measurement. An explicit expression is obtained for the minimum attainable meansquare error for certain classes of system transfer functions and disturbance power spectra, and the form of the optimum controller is derived. The results show the inherent limitations in controllability imposed by the structure of the controlled system and by the sampling process.
The stability of permanent magnets
 Author(s): C.E. Webb
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 317 –324
 DOI: 10.1049/pic.1961.0043
 Type: Article
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The paper describes tests made to compare the magnetic stability of representative martensitic and precipitationhardening (isotropic and anisotropic) permanentmagnet materials. The weakening of magnets with time after magnetization, when left as free from disturbance as possible, was measured over a period of about three years, both on unstabilized magnets and on magnets artificially stabilized by weakening them 1% or 5% by applying demagnetizing fields. Anisotropic alloys were found to be much more stable than isotropic alloys, the stability of Columax being outstanding. Alnico, in spite of its much higher coercive force, was not more stable than the martensitic steels.The effect on stability of the workingpoint of the permanentmagnet material was also examined and found to be small above the (BH)_{max} point on the demagnetization curve. Below the (BH)_{max} point, however, the stability of both isotropic and anisotropic materials was considerably reduced.Further tests were made on the effects of heating at various temperatures up to 220° C and of mechanical stress and impact. Stability in hightemperature treatment is only roughly related to stability in time tests. The results of the mechanical tests were inconclusive as the magnet assemblies available, designed primarily for longterm tests, were not suitable for subjection to severe mechanical treatment.
Topological synthesis of nonreciprocal resistance networks
 Author(s): R. Onodera
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 325 –334
 DOI: 10.1049/pic.1961.0044
 Type: Article
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The paper deals with the topological synthesis of nonreciprocal resistance networks specified by the socalled drivingconductance matrix. Synthesis of nonreciprocal networks has already been treated by H. J. Carlin and Y. Oono, and their networks are specified by scattering matrices and consequently nport impedance matrices. One of the merits of this paper, which differs from their paper, is in the determination of the connection and ideal transformers. Factors which determine the network are the connection and element resistances, and they therefore make possible the determination of the nodebranch incidence matrix and resistances so that the drivingconductance matrix may equal the given matrix. When we denote the branch e.m.f. matrix by V and the branchcurrent matrix by I, I = GV, where G is called the drivingconductance matrix, which is assumed to be given, and, in general, G′ ≠ G. If a maximal set of solutions for Gx = 0 and x′G = 0 is denoted by X as the matrix expression, X is called the zero factor of G. Provided that the zero factor X satisfies the character of a nodebranch incidence matrix, the connection can be fixed directly. If not, the connection is determined by the part of X which satisfies the character of a nodebranch incidence matrix, and the ideal transformers needed are determined by the other part. After the connection and the ideal transformers are determined, the branch resistances are determined by comparing the given matrix with the matrix calculated from the newly determined connection and the unknown branch resistances.
The impulse response of a number of identical circuits in cascade
 Author(s): K. Tharmalingam
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 335 –338
 DOI: 10.1049/pic.1961.0045
 Type: Article
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Approximate analytical expressions are derived for the impulse response of identical circuits in cascade. The results obtained from these approximate expressions, tested for an exactly solvable case, show remarkable accuracy. Cruder approximations to obtain a quick estimate of peaktopeak ring in response to a step function, and the first zero of impulse response, are also given.
Microwave propagation through round waveguide partially filled with ferrite
 Author(s): A.J. Baden Fuller
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 339 –348
 DOI: 10.1049/pic.1961.0046
 Type: Article
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The theory of microwave propagation through an unbounded ferrite medium magnetized along the direction of microwave propagation is considered, and expressions are derived for the components of the microwave field. Boundary conditions are applied, and characteristic equations are derived for four circularly symmetric shapes, namely(a) Ferritefilled round waveguide.(b) Ferrite rod at the centre of round waveguide.(c) Ferrite tube adjacent to the wall of round waveguide.(d) Ferrite tube in the centre of round waveguide.Some propagation constants have been computed for the last three shapes. The method is such that it may easily be extended to give the characteristic equations for any circularly symmetric shape of ferrite inside round waveguide in addition to the characteristic equations given in the paper. At 9370Mc/s some computed results of Faraday rotation have shown reasonable agreement with those measured on ferrite rods. The results of a specimen investigation of the variation of the propagation coefficient with change of ferrite dimension are included.
Microwave Hall effect and the accompanying rotation of the plane of polarization
 Author(s): H.E.M. Barlow
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 349 –353
 DOI: 10.1049/pic.1961.0047
 Type: Article
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Faraday rotation of the plane of polarization of an electromagnetic wave, propagated through a medium in the direction of an independently applied steady magnetic field, has been interpreted in terms of gyromagnetic action and in certain circumstances as a consequence of Hall effect.The paper calls particular attention to the Halleffect mechanism, which is shown to lead to different propagation coefficients for the righthanded and lefthanded circularlypolarized components of a plane wave.The contention is advanced that a Hall effect can be expected to arise from a displacement current in the material medium and that, as a consequence, the Faraday rotation effect in dielectrics and semiconductors may, in some cases, be significantly modified at frequencies above the microwave part of the spectrum. Some elementary calculations are given in support of this argument.
A method of calculating the transfer functions of ladder networks
 Author(s): N. Ream
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 354 –358
 DOI: 10.1049/pic.1961.0048
 Type: Article
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From the Kirchhoff equations applied to a ladder network, recurrence equations are derived for calculating the voltages and currents in terms of the output voltage and current; from these, another set of equations is obtained for working from the input end of the network. It is shown that either set of equations is particularly suitable for the numerical calculation of transfer functions. A few general formulae are included for the voltagetransfer ratio of an RC ladder network.
The part played by surface waves on the reflection at a ferrite boundary
 Author(s): L. Lewin
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 359 –361
 DOI: 10.1049/pic.1961.0049
 Type: Article
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It is shown that the solution given in a previous paper for the reflection at a ferrite boundary in a rectangular waveguide is invalid in a certain region because it implies a finite power flux into the waveguide walls. This flux can be taken care of by means of Bresler's surface waves, which can propagate in the anomalous region, and which were postulated in order to resolve a thermodynamic paradox. Their reality when the ferrite is lossy, however, requires further elucidation.
The surface impedance concept and the structure of radio waves over real earth
 Author(s): Z. Godziński
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 362 –373
 DOI: 10.1049/pic.1961.0050
 Type: Article
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The paper is concerned with the concept of surface impedance as applied to the theory of radiowave propagation over a real, i.e. inhomogeneous and irregular, earth; some of the conclusions may also be of value in the theory of waveguides, cavity resonators and certain types of aerial.The advantages and limitations of the surfaceimpedance concept are shown in connection with a very general integral equation for the field strength.The approximations and physical phenomena underlying the surfaceimpedance concept are first discussed in the simplest case of a homogeneous and flat earth. The analysis is then extended to a horizontally stratified earth; it is then possible to characterize the earth by certain effective parameters depending on frequency and the geometric structure of the soil. The same is also true in the cases of a spherical or not too excessively irregular earth. The discussion is then generalized to the case of an arbitrarily inhomogeneous earth. The height/gain function and the shape of the ellipse of polarization are discussed. Approximate boundary conditions for the Hertzian vector and Hertzian scalar function are related to the concept of surface impedance.Practical conclusions are drawn with regard to the existence and measurement of the effective earth constants and to some aspects of geological prospecting by radio methods.
The analysis of nonlinear resonant circuits
 Author(s): C.B. Newport and D.A. Bell
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 374 –385
 DOI: 10.1049/pic.1961.0051
 Type: Article
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The paper describes two graphical methods of calculating the instantaneous voltages and currents which result from feeding a sinusoidal current to a resonant circuit which employs a nonlinear inductor. The voltageintegral method uses a stepbystep approximation to the actual inductor characteristic, including hysteresis. Knowledge of the detailed waveforms facilitates the determination of the optimum magnitude and timing of a pulse to trigger a ferroresonant circuit from the dissonant to the resonant state. Calculated waveforms are satisfactorily confirmed experimentally.Alternatively, the phaseplane method allows the use of a piecewise linear approximation to the magnetization characteristic of the core of the inductor (e.g. three straight lines), but at the cost of ignoring hysteresis.
Design of cylindrical surface waveguides with dielectric and magnetic coating
 Author(s): T. Berceli
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 386 –397
 DOI: 10.1049/pic.1961.0052
 Type: Article
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The paper deals with wires whose coating has both dielectric and magnetic properties. Approximate formulae are given for the field concentration, propagation time, group velocity, power distribution, characteristic impedance, losses and maximum transmissible power for such coated wires.The magnetic coat concentrates the field more strongly than does the dielectric one. The field concentration increases quickly with increase of permeability and hardly depends on permittivity.The attenuation is due to the conductive, dielectric and magnetic losses of the guide. The dielectric loss depends also on permeability, and vice versa. The total loss of a given transmission line as a function of field concentration has a minimum, which can be achieved by a coating of appropriate thickness.To determine the maximum transmissible power, two formulae can be used. One determines the maximum transmissible power from the highest permissible value of electric field strength, and the other from the highest permissible degree of overheating.The paper concludes with a description of design procedure for surface waveguides, illustrated by an example.
A broadband waveguide junction containing dielectric
 Author(s): P.J.B. Clarricoats
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 398 –404
 DOI: 10.1049/pic.1961.0053
 Type: Article
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A method is described for obtaining a broadband impedance match between two joined waveguides of differing crosssection. The method involves the use of an axially mounted dielectric which partially fills the waveguide crosssection. With an appropriate choice of dielectric crosssectional area and permittivity the electromagnetic field is mainly confined to the region of the rod. Under these conditions the waveguide crosssection may be abruptly changed without appreciable reflection. The case of two joined circular waveguides containing an axial dielectric rod is treated theoretically for H_{01}mode propagation. A similar configuration is studied experimentally for the H_{11}type mode of propagation. In both cases an appreciable reduction in reflection coefficient is demonstrated when the rod is present. The application of the principle to other waveguide crosssections is briefly mentioned.
Certain approaches to electromagnetic field problems pertaining to dynamoelectric machines
 Author(s): K.C. Mukherji
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 405 –411
 DOI: 10.1049/pic.1961.0054
 Type: Article
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Currentcarrying circuits in electrical rotating machines give rise to electromagnetic fields which are modified by surface polarities induced in adjacent ferromagnetic media and by eddy currents induced in neighbouring conducting media. The paper reviews certain approaches towards solving some of the electromagnetic problems involved and introduces a method for taking account of the reaction of eddy currents induced in a ferromagnetic medium on their inducing field.
A note on optimum linear multivariable filters
 Author(s): R.J. Kavanagh
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 412 –417
 DOI: 10.1049/pic.1961.0055
 Type: Article
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The explicit solution for the optimum linear physically realizable multivariable filter involves the factorization of a powerspectra matrix into two matrices, one having all its poles in the lefthalf pplane and the other having all its poles in the righthalf pplane. No general method of accomplishing this factorization has previously been available.This note contributes a method of factorizing any powerspectra matrix in the required manner. As a result, the explicit solution for the optimum filter is obtainable in a number of cases not previously solvable without resort to implicit methods. In the course of developing the factorization method it is shown that it is always possible to obtain a physically realizable multivariable system which will transform any given set of signals into an equal number of incoherent whitenoise signals. Similarly it is shown that a physically realizable multivariable shaping filter may always be found to transform a set of incoherent whitenoise signals into an equal number of signals with any desired powerspectra matrix.
Factors affecting the behaviour of an electric arc under transient conditions
 Author(s): I.A. Black
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 418 –423
 DOI: 10.1049/pic.1961.0056
 Type: Article
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The paper describes an investigation into the relationship between voltage and current in an arc under transient conditions. It is shown theoretically that the arc resistance is a function of the energy in the arc column, while the power loss from the arc is a function of arc resistance.The relationship between arc resistance and change of arc energy has been obtained by injecting pulses into a static arc. This relationship is valid for periods from 3 μs up to at least a millisecond. The relationship between power loss and arc resistance has also been derived experimentally. Measurement of the electrode voltage drop under transient conditions has enabled electrode and arc column effects to be separated.It is shown how the relationship between resistance and energy, as well as between power loss and resistance, is affected by a change of arc length, initial arc current and electrode material.Finally, the experimental results are compared with dynamic arc equations published in the literature.
An experimental proton linear accelerator using a helix structure
 Author(s): D.P.R. Petrie ; R. Bailey ; D.G. KeithWalker ; H. Longley ; D.R. Chick
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 424 –432
 DOI: 10.1049/pic.1961.0057
 Type: Article
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The paper describes the design and construction of a short experimental length of linear accelerator using a helical waveguide as the slowwave structure to accelerate protons from 2.5 MeV to 4 MeV.Factors influencing the design of the helix structure are considered; these include the maximum voltage between turns which can be tolerated and the available power and frequency of the r.f. supply. The theory of a helix supported on a dielectric tube is given, and from the results the variations of pitch are determined to give the required acceleration.The accelerator was driven by a pushpull triode oscillator operating under 6μs pulsed conditions at 300Mc/s with a peak output of 600 kW. The oscillator and r.f. components are described in detail.The beamenergy spectrum at the output of the accelerator was measured for a variety of working conditions, changes being made in beamenergy input and power and frequency of the r.f. supply. The results obtained confirm the theory and show that with certain restrictions a helix slowwave structure of the type described provides a convenient me hod of proton acceleration.
Wideband coupling systems between a waveguide and a transmission line
 Author(s): B. Rogal and A.L. Cullen
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 433 –437
 DOI: 10.1049/pic.1961.0058
 Type: Article
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The paper describes a wideband microwave system suitable for coupling power between a coaxial line and a waveguide or between two waveguides. Such a system can be applied to normal matched transmission as well as, for example, to coupling power between a coaxial klystron cavity and a waveguide. An appreciable improvement in performance over other schemes results in an almost constant power transfer over a bandwidth in the region of 25%. A practical example of the system in Xband is described.
The conductivity of oxide cathodes. Part 10: Spontaneous generation of negative ions
 Author(s): G.H. Metson
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 438 –449
 DOI: 10.1049/pic.1961.0059
 Type: Article
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The experimental work described here proves that a bariumstrontiumoxide matrix is thermally unstable at 1020°K and continuously generates negative ions of oxygen in its hollow pore system. The bariumoxide component of the matrix is essentially stable and the strontiumoxide component is the oxygenion generator. The action is a fundamental one and proceeds at constant and unalterable rate. Factors determining the equilibrium concentration of free oxygen ions in the pores are examined and described. One conclusion reached is that donor concentration of a thermallyactivated bariumstrontiumoxide matrix is almost wholly strontium metal.
The conductivity of oxide cathodes. Part 11: Thermal stability of the alkalineearth oxides
 Author(s): G.H. Metson and H. Batey
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 450 –454
 DOI: 10.1049/pic.1961.0060
 Type: Article
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The three common alkalineearth oxides are examined for thermal stability at 1200°C. In an experimental arrangement involving a massive evaporation from a platinum substrate it is shown that barium oxide is removed in the form of unchanged molecules while strontium and calcium oxides leave the substrate in elemental form as metal and oxygen. It is concluded that the dissociation is a thermal one and not concerned with the nature of the substrate.
Transitional electrical units
 Author(s): Leo Young
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 455 –457
 DOI: 10.1049/pic.1961.0061
 Type: Article
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The paper is concerned with the six metric systems of electrical units in common use. The equations of each system differ by constants involving 4 π and (approximately) 3 × 10^{10}. Although this is well understood and accepted, difficulties sometimes arise when a comparison is made between the units or quantities of different systems. The paper endeavours to show that these difficulties are largely semantic, and that they can be overcome with ‘transitional electrical units’ by converting a given unit into its transitional counterpart, and thence into the unit of the desired system.
Internal waveform distortion in siliconiron laminations for magnetization at 50 c/s
 Author(s): F. Brailsford and J.M. Burgess
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 458 –462
 DOI: 10.1049/pic.1961.0062
 Type: Article
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The internal distribution of magnetic flux and eddy currents to be expected in a homogeneous magnetic lamination having a sinusoidal total flux has been investigated experimentally using an analogue. It is concluded that the anomalous loss in laminations found to occur in practice cannot be accounted for by waveform distortions within the lamination.
The motion of coldcathode arcs in magnetic fields
 Author(s): A.E. Guile ; T.J. Lewis ; P.E. Secker
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 463 –470
 DOI: 10.1049/pic.1961.0063
 Type: Article
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The paper first discusses the way in which theories concerning the motion of coldcathode arcs when acted upon by a magnetic field have ranged from proposing cathodefall mechanisms for retrograde motion to column processes for forward motion. A very recent mechanism proposed by Ecker for retrograde motion is then examined and found to be capable of extension to higher pressures where forward motion occurs.Previously published experimental results for forward motion are viewed in the light of this mechanism, which is found to be consistent with them, and some features which had hitherto been anomalous may now be explained. Thus there emerges a unified model for the cathode spot and fall region which appears to be valid for both forward and retrograde movements of the arc. It is suggested that this provides a vital step in the approach to the development of certain devices in which arc discharges take place.
Frequency response analysis of displacement governing in synchronous power systems
 Author(s): P.A.W. Walker and A.S. Aldred
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 471 –477
 DOI: 10.1049/pic.1961.0064
 Type: Article
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The paper describes the application of the frequencyresponse concept to the analysis of displacement governing in a synchronous machine system. The governor loop is shown to combine with the basic closedloop pattern of the generator and modifies only the feedback element in the original basic loop. The analysis is used to compare stability boundaries for different governor conditions, these boundaries being derived by the application of the Nyquist stability criterion. The results obtained by this method, although based on smalldisplacement theory, were found to be in agreement with those obtained from a powersystem simulator.The effects of phase lags, arising in the steam header of the turbine and the servo mechanism operating the throttle valve, on the stability of the system are considered together with that of a secondderivative stabilizer. An examination is also made of the damping in the system, as this provides a useful appraisement when comparing the relative stability of different configurations in the governor loop.
Analytical determination of the characteristics of enclosed and oilimmersed fuses
 Author(s): Colin Adamson and M. Viseshakul
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 478 –491
 DOI: 10.1049/pic.1961.0065
 Type: Article
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In a previous paper the authors dealt with the case of semienclosed fuses, manufactured from uniform thin strip or with single or double discontinuities in their crosssections. An analytical solution for the time/current characteristic of such fuses was shown to exist, which was in very close correlation with experimental derivations of the same characteristics.This work has now been extended in two ways. First, the analytical derivation of fuse characteristic has been extended to cases of fuses with n discontinuities in their crosssections, where n > 2; this work was carried out with the aim of investigating the full range of alternative characteristics available from such fuses. Secondly, and the most important part of the work, has been the extension of the solution obtained for a semienclosed fuse to fuses of similar metallic construction but immersed in oil or enclosed in a silicatype filler.Having established a method and form of solution, a substantial amount of computation is necessary in any one case; in order to facilitate computation, a simple form of transient analogue computer has been used, and is described in the paper. In the case of fuses immersed in oil or enclosed in silicatype filler, the main problems have been to establish the parameters of heat transfer prior to finding a form of solution of the relevant equations.The Appendices contain representative Tables of results in the form in which they were obtained from the analogue computer, and an analysis showing the feasibility of establishing a single series of Tables of analoguecomputer results for fuses with multiple discontinuities in crosssection.
The launching of surface waves by an endfire array of slots
 Author(s): A.L. Cullen and J.A. Staniforth
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 492 –495
 DOI: 10.1049/pic.1961.0066
 Type: Article
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An endfire array of slots suitable for launching a surface wave on a dielectriccoated metal sheet is described and analysed. The analysis is based on the representation of the slots as magnetic dipoles in the plane of the sheet, their axes being perpendicular to the line of the array.In a practical embodiment of the scheme the elements take the form of slots fed by quarterwavelength branch guides series fed from a waveguide partially filled with dielectric mounted beneath the metal sheet. Experimental results are given which support the theoretical conclusion that a high launching efficiency is possible. A launching efficiency of 95% is obtained theoretically for a 12slot array launching a surface wave on a metal sheet coated with dielectric of relative permittivity 2.56 and of thickness 0.125 in at a frequency of 9.38 Gc/s.
Backward waves in waveguides containing dielectric
 Author(s): P.J.B. Clarricoats
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 496 –501
 DOI: 10.1049/pic.1961.0067
 Type: Article
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A method is described for determining the conditions which ensure backwardwave propagation in dielectricloaded inhomogeneous waveguide structures. It is established that backwardwave propagation can be ensured for the hybrid H_{11}mode in a circular waveguide containing an axial dielectric rod whose relative permittivity exceeds approximately 9.4. The possibility of other inhomogeneouswaveguide modes exhibiting backwardwave properties is also examined.
The relation between discrete periodic inputs, the transfer function and the transient response of a system
 Author(s): T. Glucharoff
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 502 –508
 DOI: 10.1049/pic.1961.0068
 Type: Article
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Sampleddata systems are characterized by the presence of discrete signals at some point of the system, but the overall output is usually a continuous function of time. It is shown that the pulse sequence of discrete periodic signals, which result in a finitesettlingtime response when applied to the input of a system, can be determined directly from the system transient response. Such a pulse sequence can be used to design a discrete controller to compensate the system, when its transfer function is not known. Further, it is shown that the transfer function of a system can be found once an input pulse sequence has been determined, with an accuracy limited only by the accuracy of the given transient response.
A theoretical and analogue approach to stray eddycurrent loss in laminated magnetic cores
 Author(s): D.A. Jones and W.S. Leung
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 509 –515
 DOI: 10.1049/pic.1961.0069
 Type: Article
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A method of obtaining the interlaminar eddycurrent loss in laminated magnetic cores is devised by using a resistancenetwork analogy. It is assumed that in a laminatedcore section the flux distribution is uniform, that there is a uniform resistivity in the direction across the laminations and that the IR drops in the direction along the planes of the laminations are negligible compared with those in the perpendicular direction. The stray eddycurrent loss is derived as a function of the resistivity ratio between the two directions. The network analogy leads to the subsequent estimation of the effect on core loss of any shortcircuiting paths in the section. An experimental technique was developed to investigate the eddycurrent distribution in any conductive network through which a uniform alternating magnetic flux passes. The eddycurrent distribution for an isotropic section was first obtained. An analogy to the laminatedcore section from the point of view of conductivity was effected using a differential wire network whose resistivity in one direction was of the order of 10^{4} times that in the perpendicular direction. The eddycurrent distribution in such a network under an alternating magnetic field was found to confirm the theoretical calculations for core sections with and without interlaminar shortcircuits.
A hunting analysis of a permanentmagnet alternator and a synchronous motor
 Author(s): M.H. Walshaw and J.W. Lynn
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 516 –527
 DOI: 10.1049/pic.1961.0070
 Type: Article
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p.
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(12)
Little has hitherto been written about the transient analysis of interconnected salientpole synchronous machines of comparable size, where infinite busbars cannot be assumed to exist.The paper describes theoretical and practical work carried out on a simple power system of this type, in which a 60 kW permanentmagnet alternator supplies power to a synchronous motor. For analytical purposes the permanentmagnet alternator is shown to be equivalent to a conventional alternator with a constant field voltage. The measurement of the parameters of the machines is described and the steadystate performance of the interconnected system is predicted by Kron's method of analysis.The hunting equations of the system are examined, and a frequencyresponse method involving Nyquist's stability criterion is used to predetermine the effects of armature resistance on the hunting stability of the system under various conditions of load and saturation. A digital computer is used to perform the calculations and the predicted results are found to agree well with those obtained experimentally from the actual system.
Discussion on “Orthogonal codes”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, page: 528 –528
 DOI: 10.1049/pic.1961.0071
 Type: Article
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p.
528
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Discussion on “Calculation of the current in nonlinear surgecurrentgenerator circuits”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, page: 529 –529
 DOI: 10.1049/pic.1961.0072
 Type: Article
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p.
529
(1)
Discussion on “Eddycurrent effects in rectangular ferromagnetic rods”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 529 –530
 DOI: 10.1049/pic.1961.0073
 Type: Article
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p.
529
–530
(2)
Discussion on “Electric and magnetic images”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, page: 530 –530
 DOI: 10.1049/pic.1961.0074
 Type: Article
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p.
530
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Discussion on “Optimum combination of pulse shape and filter to produce a signal peak upon a noise background”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 531 –532
 DOI: 10.1049/pic.1961.0075
 Type: Article
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p.
531
–532
(2)
Discussion on “An analytical review of powersystem frequency, time and tieline control”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, page: 532 –532
 DOI: 10.1049/pic.1961.0076
 Type: Article
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p.
532
(1)
Discussion on “Numerical evaluation of inductance and a.c. resistance”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 533 –534
 DOI: 10.1049/pic.1961.0077
 Type: Article
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p.
533
–534
(2)
Discussion on “Frequency spectrum distortion of random signals in nonlinear feedback systems”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 534 –535
 DOI: 10.1049/pic.1961.0078
 Type: Article
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p.
534
–535
(2)
Discussion on “The stability of permanent magnets”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, p. 535 –536
 DOI: 10.1049/pic.1961.0079
 Type: Article
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p.
535
–536
(2)
Discussion on “Matrix analysis of constrained networks”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 14, page: 536 –536
 DOI: 10.1049/pic.1961.0080
 Type: Article
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p.
536
(1)
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