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Electrical Engineers, Proceedings of the Institution of

Issue 11 • Date November 1978

 This issue contains several parts.Go to:  Part R 

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Displaying Results 1 - 25 of 28
  • Signal/noise performance evaluation for colour-television picture sources

    Publication Year: 1978 , Page(s): 1195 - 1198
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The signal/noise performance of a colour picture source is known to be an extremely difficult parameter to measure and specify. Owing to the complexity of signal processing within the picture chain, conventional methods of measuring r.m.s. noise levels at the outputs of the picture source can give a figure of merit that is substantially different from that obtained by direct observation of the subjective noise impairment of the final displayed picture. The paper describes the results of research to establish standard test procedures for the measurement of noise in picture sources. It is shown that noise-measuring equipment may be designed that yields a figure of merit termed `the display signal/noise ratio¿ for the source under test. This figure of merit corresponds well with the subjective noise performance of the equipment. View full abstract»

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  • Detection of totally symmetric Boolean functions with the aid of decimal combination tables

    Publication Year: 1978 , Page(s): 1199 - 1202
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (481 KB)  

    A method of detecting and identifying the total symmetry of an n-variable Boolean function F with the use of decimal combinational tables is presented. Instead of using maps, charts or truth tables, with permutations and complementations of variables, this method uses a table which gives for each minterm mi (that makes F=1) the number of adjacencies w1 ranging from 0 to n. The detection of the variables of symmetry is based on finding out from the table a pair of minterms m* and its is complement m* (or pairs of similar minterms) that among all minterms appearing in F (or in F¿) are distinguished by having w1 equalling n or 0. The parameter w1 is the total number of other minterms appearing in F (or in F¿) that differ from any function minterms, e.g. m by one complementation of literal, and is easily determined from the table of combinations. The minterms m and m* are likely contenders to define the literals of symmetry and merit further investigation. The identification of F as a totally symmetric function is completed if and when a set of a-numbers is determined from the combinational table. The paper describes the construction of the combinational table and illustrates the method with example. View full abstract»

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  • Performance results for an m.i.m.d. computer organisation using pipelined binary switches and cache memories

    Publication Year: 1978 , Page(s): 1203 - 1207
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (598 KB)  

    Simulation results of a multiple-instruction multiple-data-stream (m.i.m.d.) organisation are presented. The results deal with the behaviour of throughput performance with respect to variations in cache-memory parameters, number of processors and processing time, of a m.i.m.d. system in which a pipelined binary switch is used as the interconnection network. The results indicate the viability of systems utilising cache memories and pipelined switches which exhibit performance comparable to systems with crosspoint switches. This aspect is attractive, since it is likely that m.i.m.d. systems with pipelined binary switches can be implemented at a lower cost than those with crosspoint switches. View full abstract»

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  • Characteristics of interfering signals in aeronautical h.f. voice channels

    Publication Year: 1978 , Page(s): 1208 - 1212
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (721 KB)  

    Interference from other users can be an important source of errors in aeromobile h.f. data transmission and is often more detrimental than the effects of multipath propagation and atmospheric and receiver noise. This paper describes briefly an initial investigation into the frequency and time characteristics of interfering signals within aeronautical h.f. voice channels and considers modem proposals that can improve the performance of slow-rate data transmissions in the presence of such interference. View full abstract»

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  • Compact resonant slot for waveguide arrays

    Publication Year: 1978 , Page(s): 1213 - 1216
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (483 KB)  

    The development of an I-shaped novel geometry for radiating slots entirely in the narrow wall of a waveguide is outlined. I2R losses in the metal of the waveguide wall are identified as an undesirable feature of impedance-loaded slots or slots of reduced height. The I-shaped geometry developed does not include these features, and is demonstrated to be a useful low-loss waveguide array element, offering a wide range of coupling values. View full abstract»

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  • Multiport network analysis by matrix renormalisation: extension to 5- and 6-ports

    Publication Year: 1978
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (127 KB)  

    The principle of network analysis by scattering matrix renormalisation, described in earlier papers, is extended to 5- and 6-port networks. The 5-port renormalisation transforms are given in detail and the 6-port transforms in symbolic form. A new method of deriving the transforms is briefly described. View full abstract»

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  • Application of forward-error correction to a rayleigh fading h.f. communication channel

    Publication Year: 1978
    Save to Project icon | PDF file iconPDF (120 KB)  
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  • Design optimisation of starting windings for 1-phase induction motors

    Publication Year: 1978 , Page(s): 1219 - 1222
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (451 KB)  

    The paper describes a method of minimising the material cost of starting windings for split-phase induction motors. The quantities considered as variables are the number of turns and the wire diameter. The method is considered in the context of a typical starting specification for this type of motor, and the effect of various constraints is discussed. View full abstract»

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  • Scale-model linear induction motors with solid iron secondaries

    Publication Year: 1978 , Page(s): 1223 - 1226
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (381 KB)  

    The performance of large linear induction machines with nonlinear secondaries is predicted utilising the principle of electromagnetic similitude and small-scale models. A set of scaling factors is derived and confirmed initially using a pair of physically similar solenoids with solid iron cores. Static and dynamic characteristics of the model are scaled and compared with the full-size machine for both dynamic a.c. and dynamic d.c. braking modes. It is concluded that the technique can be used, instead of analysis, to give adequate prediction of performance. View full abstract»

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  • Radial tooth-ripple forces in induction motors due to the main flux

    Publication Year: 1978 , Page(s): 1227 - 1231
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    Radial tooth-ripple forces that are associated with tooth-ripple flux pulsations give rise to undesirable effects in induction motors. The relation between these pulsations due to the main flux and the airgap geometry is considered. By evaluating the amplitude of the tooth-ripple carrier, for a wide range of parameters, general conclusions are drawn that help in the understanding of design problems. View full abstract»

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  • Interlamination voltages in large turbogenerators

    Publication Year: 1978 , Page(s): 1232 - 1238
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (884 KB)  

    The magnetic flux in a generator induces a voltage between adjacent laminations of the stator core. These voltages are uniformly low (less than 50 mV) along the length of the core, and so only light interlamination insulation is required to prevent troublesome heating in the core. However, near the end of the core, additional interlamination voltages are induced by the axial magnetic fields in the core-end region and the radial leakage field at the core back. These voltages result from the segmentation of the laminations, and their magnitude depends on the way in which individual laminations are earthed to the stator building bars. These `segmentation voltages¿ are calculated by considering the eddy currents induced in the laminations by the axial magnetic fields, the currents flowing from the laminations to the stator building bars and the currents induced in these bars by the radial leakage fields. It is shown that, if the contact resistance between the laminations and the building bars is relatively high, and varies from contact to contact, the segmentation voltages are an order of magnitude higher than those induced by the main generator flux and hence sufficient to cause troublesome heating in damaged areas of the core. View full abstract»

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  • Design of fail-safe electromagnetic train-speed sensor

    Publication Year: 1978 , Page(s): 1239 - 1244
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (670 KB)  

    The paper describes the design of a fail-safe sensor used for the detection of the speed of a moving railway vehicle. The sensor is required for use in automatically controlled trains that run at one of a number of predetermined speeds, selected with reference to safety criteria, and governed by conditions ahead of the train. The device uses an axle-coupled permanent-magnet a.c. generator that, at the predetermined speed, saturates a transformer with low-frequency current, choking the passage of an audio-frequency signal from a constant-voltage source, and hence cutting off the output. Positive feedback is employed to sharpen the cut-off slope. A computer model based on a sinusoidal analytical method, superimposing the low and audio-frequency signals, predicts the possibility of in stability and hysteresis occuring in the output characteristic under certain conditions. Computed and test results are found to be in good agreement, and a series of circuit-design criteria are derived. View full abstract»

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  • Turboalternator excitation control incorporating nonlinear state feedback

    Publication Year: 1978 , Page(s): 1245 - 1246
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (274 KB)  

    The improvement in transient performance obtained by use of a nonlinear combination of feedback of several system states to the excitation circuit of a turboalternator is described. It is also shown that acceptable system performance can be obtained with only two extra system-states fedback in this nonlinear manner. View full abstract»

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  • Step response of a governed hydrogenerator

    Publication Year: 1978 , Page(s): 1247 - 1248
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (182 KB)  

    Stable control of the frequency in an electrical power system is essential to ensure continuity of supply. It is determined by the combined effect of the speed governors fitted to the generating sets throughout the system. The power output response of a steam-driven set to sudden loss in generating capacity is initially fast, but, after a few seconds, loss of boiler pressure reduces the output of the set. On the other hand, the response of a hydroelectric generator, although initially less rapid (due to the need to accelerate the water column), can be maintained at a high level for as long as storage water is available. Hydrosets are therefore particularly useful for system-frequency control provided they are fitted with governors that ensure a fast, but stable, response to a sudden change of load. In practice, governor settings are usually made during commissioning on the basis that the set will be stable when fully loaded and electrically isolated from the rest of the system. Attention, in the paper, is therefore given to the transient speed response of a single, isolated, governed hydrogenerator operating at, or near, full load. View full abstract»

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  • Transient stability augmentation with a braking resistor using optimal aiming strategies

    Publication Year: 1978 , Page(s): 1249 - 1255
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (811 KB)  

    A braking resistor is used to improve the transient stability of a one-machine, infinite-busbar system. The minimum-angle and minimum-norm aiming strategies are used to provide explicit feedback solutions to the control problem. Several choices of the aim state are proposed. Simulation results show that both these methods result in an improvement of the critical clearing time, and that they result in a more desirable state trajectory than simple on/off control based on angular-velocity measurements. The sensitivity of the control strategies to inaccurate angle information is discussed. View full abstract»

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  • Discussion on ¿Electric fuses¿

    Publication Year: 1978 , Page(s): 1256 - 1258
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  • Discussion on "Measurement of rotor temperatures of a 500 MW turbine generator with unbalanced loading" and "Analysis of the losses in a turbine-generator rotor caused by unbalanced loading"

    Publication Year: 1978 , Page(s): 1259 - 1264
    Save to Project icon | PDF file iconPDF (957 KB)  
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  • A.C.-d.c. and a.c.-a.c. convertor control with selective reduction of line harmonics

    Publication Year: 1978 , Page(s): 1269 - 1270
    Cited by:  Papers (6)
    Save to Project icon | PDF file iconPDF (206 KB)  
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  • Torque optimisation of a variable-reluctance stepping motor

    Publication Year: 1978 , Page(s): 1271 - 1272
    Save to Project icon | PDF file iconPDF (247 KB)  
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  • Use of a voltage follower for the error reduction of a voltage transformer

    Publication Year: 1978 , Page(s): 1272 - 1273
    Save to Project icon | PDF file iconPDF (275 KB)  
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  • Variable-speed single-phase linear induction motor

    Publication Year: 1978 , Page(s): 1273 - 1274
    Save to Project icon | PDF file iconPDF (218 KB)  
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  • Design of stochastic optimal feedback control systems

    Publication Year: 1978 , Page(s): 1275 - 1284
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1285 KB)  

    The design of stochastic, linear, multivaribale feedback systems is considered where the plant is constant and the noise processes are stationary. The plant can be unstable and nonminimum-phase and feedback-system dynamics can be modelled. Approximate methods are described for limiting the effects of plant saturation and for modelling transport delays. The closed-loop system is assumed, to have a coloured process, disturbance and measurement noise inputs and a coloured reference input. The plant disturbance and the closed-loop-system reference inputs are also assumed to contain deterministic components, e.g. step or ramp signals. The design procedure is original and involves two stages. A performance criterion is defined first that is not sensitive to the deterministic signals, and this defines the closed-loop controller. The resulting closed-loop system acts as an optimum regulator to minimise the effects of stochastic disturbances. A second tracking-error performance criterion is then specified that determines the optimal reference input to the closed-loop system. This reference signal is generated by two optimal open-loop controllers. One controller ensures the plant output is following a desired trajectory, and the second acts as a feedforward controller to offset plant disturbances. View full abstract»

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  • Decoupling controller design via exact model-matching techniques

    Publication Year: 1978 , Page(s): 1285 - 1289
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (483 KB)  

    This paper presents a new method for synthesising decoupling controllers for linear time-invariant multivariable systems. The novel approach proposed is based on the idea of formulating, and subsequently solving, the decoupling problem as an exact model-matching problem. This, in effect, results in reducing the decoupling problem to one of solving a linear system of equations. View full abstract»

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  • Design of hierarchical computer control systems for industrial plant. Part 1: Modelling of the output dynamics of a multiple-effect evaporator

    Publication Year: 1978 , Page(s): 1290 - 1298
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1152 KB)  

    The paper describes the application of an interactive identification procedure, based on recursive least-squares analysis and supported by a graphics-display facility. The derivation of a multivariable equation is reviewed. This is structured in terms of inputs and outputs, and is demonstrated to provide a very effective means for the modelling of the dynamics of industrial plant. Application is to a multiple-effect evaporator that is used as a first stage in the concentration of milk for the preparation of milk powder. The interactive facility is integrated into a scheme for the design and implementation of hierarchical computer-control systems for the milk-powder plant. 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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