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Electrical Engineers, Proceedings of the Institution of

Issue 6 • Date June 1977

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Displaying Results 1 - 25 of 26
  • Process-parameter variability in the manufacture of m.o.s. integrated circuits

    Publication Year: 1977 , Page(s): 505 - 507
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (498 KB)  

    The integrated circuits produced on a manufacturer's process line incorporate a standardised m.o.s. transistor providing a set of seven process-parameter values per die at the wafer-probe stage. A statistical analysis of the parameters measured on batches of wafers withdrawn in consecutive weeks from the line shows that the batches received different process treatments. A similar analytical procedure applied to the individual wafers of the batches yields the more surprising result that the wafers were also dissimilarly processed. View full abstract»

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  • Orthogonally aliased fourier transforms for the analysis of sparsely populated frequency spectra

    Publication Year: 1977 , Page(s): 508 - 510
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (409 KB)  

    A trick permits the use of several aliased fast Fourier transforms (f.f.t.) in place of a single unambiguous f.f.t. If the proportion of active spectral lines, or directions of arrival, is well under 1%, their location, but not the amplitude, can then be computed with a dramatically reduced workload. View full abstract»

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  • Theoretical analysis of the junction discontinuity between a straight and a curved section of rectangular waveguide

    Publication Year: 1977 , Page(s): 511 - 516
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    The asymptotic form of orthonormal eigenfunctions in the curved guide is obtained, and an integral equation is set up for the junction field. The latter is found as a power series in theguide curvature, and the first-order coefficient is determined explicitly. The odd-order mode-conversion coefficients are found to the first order and vary asymptotically as the inverse cubeof the mode order. A variational technique then determines the reflection coefficient exactly, to the second order in the curvature expansion parameter. The junction parameters are found to this order of accuracy, and are shown to involve a junction transformer which represents the radiation coupling between the dominant modes in the straight and curved guide sections. The even-order mode-conversion coefficients are found by a formulation analgous to that used for the reflection coefficient, and are shown to vary as the square of the curvature and asymptotically asthe inverse cube of the mode number. The form of the junction field is determined and is shown to possess a logarithmic singularity in its second derivative at the guide wall. View full abstract»

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  • Computer-aided design of thin-film optical devices

    Publication Year: 1977 , Page(s): 517 - 518
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (239 KB)  

    The paper describes a technique for the computer-aided design of optical devices which are structured from multilayer thin films. The method overcomes some of the disadvantages usually associated with the design of optical multilayer systems, such as a requirement for approximate initial designs and excessive computing time. Results are presented for both bandpass and bandstop optical filters. The design system has been planned to integrate with the requirements of a computer-controlled process for manufacturing optical devices. View full abstract»

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  • Computer-aided wideband antenna design in the broadcast band II

    Publication Year: 1977 , Page(s): 519 - 523
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (469 KB)  

    The paper describes the design of a wideband antenna suitable for relay stations broadcasting in band II over the range 88¿100MHz. The optimisation of various design parameters was carried out with a computer program to meet the desired performance standards. Subsequent measurements on a scale model confirmed the calculations. The antenna has an operating bandwidth from 88 to 100 MHz: An outline of the method of computation is appended. View full abstract»

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  • Erratum: Input admittance of a circular waveguide aperure loaded with an iris

    Publication Year: 1977
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  • Characteristics of j.f.e.t.s. taking the separation of gate electrode from the source and drain electrodes into account

    Publication Year: 1977
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (113 KB)  

    The performance characteristics of a junction field-effect transistor (j.f.e.t.) are evaluated considering the presence of the gap between the gate electrode and the source and drain terminals. It is concluded that the effect of the gap is to demand a higher drain voltage to maintain the same drain current. So long as the device is operated at the same drain current, the presence of the gap does not change the performance of the device as an amplifier. The nature of the performance of the device as a variable resistor is not affected by the gap if it is less than or equal to the physical height of the channel. For gap lengths larger than the channel height, the effect of the gap is to add a series resistance in the drain. View full abstract»

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  • Probabilistic reliability of a canonical fault-tolerant standby redundancy

    Publication Year: 1977
    Save to Project icon | PDF file iconPDF (209 KB)  
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  • On 1-step majority-logic decoding

    Publication Year: 1977 , Page(s): 527 - 528
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  • Linear dependence between nodal powers in probabilistic a.c. load flow

    Publication Year: 1977 , Page(s): 529 - 534
    Cited by:  Papers (14)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (626 KB)  

    The paper describes how positive and negative dependence between the nodal powers of a power system can be formulated and included in the probabilistic a.c. load-flow problem. A typical system is analysed using nodal powers that are assumed, first, to be totally independent, and, secondly, to exhibit dependence. This analysis indicates clearly that it is not possible to predetermine the effect of dependence and illustrates how the standard deviations and the shape of the probability-density curves of the calculated parameters change when dependence between the input nodal powers is assumed. View full abstract»

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  • Reliability modelling and evaluation of transmission and distribution systems

    Publication Year: 1977 , Page(s): 535 - 541
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1030 KB)  

    This paper considerably extends the modelling and evaluation techniques presently used in assessing the reliability of transmission and distribution networks. The concepts described lead to a realistic analysis of such systems. The most important features that are described concern the incorporation of all realistic failure and restoration modes, development of the concept for overall system indices, inclusion of variable repair times and the ability to extend the usual loss of continuity criterion to include loss of quality, this often being of vital importance. All the techniques and concepts discussed were used to analyse a typical system, the results of which are included in the paper. View full abstract»

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  • Magnetic permeance of doubly-salient airgaps

    Publication Year: 1977 , Page(s): 542 - 544
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (261 KB)  

    Design data are presented in the form of permeance factors for the airgap between doubly-slotted surfaces, for the cases in which the teeth are perfectly aligned and symmetrically misaligned. Data previously available are thus extended to become applicable to stepping motors as well as to other types of machine, and the new data are in a more convenient form. The permeance factors are used to calculate the average force over a step length, and these results confirm the accuracy of earlier studies based on more approximate data. The effect of finite slot depth is discussed, and the solution of the troublesome implicit equations involved is obtained using a patternsearch minimisation procedure. View full abstract»

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  • Discussion on "Thyristor chopper control and the introduction of harmonic current into track circuits" and "Thyristor chopper control and the introduction of harmonic current into track circuits: practical tests"

    Publication Year: 1977 , Page(s): 545 - 548
    Save to Project icon | PDF file iconPDF (675 KB)  
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  • Analysis of synchronous generator sequential short circuits

    Publication Year: 1977 , Page(s): 549 - 553
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (612 KB)  

    A method of analysing sequential short circuits on a synchronous machine is presented, and is applied to the detailed analytical solution for the armature currents following a line-to-line/3-line and a line-to-neutral/3-line-toneutral short circuit. The analysis is carried out in the d, q, o reference frame by a Laplace transform method using the voltages during the unbalanced s.c., which are known from previous analyses. The results show that, following the 3-phase s.c., the currents decay with the same time constants as during a simultaneous 3-phase s.c. together with an additional time constant for the `o¿ component in the s.c. involving the neutral. The magnitudes of all these components, not just the asymmetrical component as indicated by previous workers, are influenced by the duration and time constants of the unbalanced s.c. As pointed out by previous authors, it is shown that a sequential s.c. can be more severe than a simultaneous s.c., if the duration of the initial s.c. is short compared with the subtransient time constants. The effect of subtransient saliency, which is included in the analysis, is also discussed. View full abstract»

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  • Simplification, by use of Ku's transformation, of the analytical study of an asynchronous motor fed by stepped voltages

    Publication Year: 1977 , Page(s): 554 - 556
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (259 KB)  

    If the values of the 2p steps of equal duration T/2p, generating an alternating signal whose period is T, are chosen in order to eliminate all the harmonics whose order is between 2 and p, Y.H. Ku's transformation of a 3-phase balanced system of such signals gives components of period T/2p, when p is equal to three or a multiple of three. Only one-2pth of T is necessary to study the supply of a load as it is shown in the case of an asynchronous motor. View full abstract»

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  • Static Scherbius system of induction-motor speed control

    Publication Year: 1977 , Page(s): 557 - 560
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    The paper describes a control system in which a cycloconvertor is connected between the secondary winding of a 3-phase induction motor and the a.c. mains supply to give variable-speed subsynchronous and supersynchronous operation. Considerations of power flow in the secondary circuit show that for stable operation the cycloconvertor must be controlled from a frequency signal source synchronised to the secondary e.m.f. A secondary e.m.f. signal generator is described which produces the necessary control signal and provides a means of power-factor control. A simple model is proposed in which the cycloconvertor appears as a current source in the secondary circuit of the machine. Experimental results are presented showing smooth operation below, through and above synchronous speed with either driving or braking torques. View full abstract»

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  • Discussion on ¿A.C. security assessment¿

    Publication Year: 1977 , Page(s): 561 - 562
    Save to Project icon | PDF file iconPDF (411 KB)  
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  • Discussion on "Long-term-creep assessment for overhead-line conductors"

    Publication Year: 1977 , Page(s): 562 - 564
    Save to Project icon | PDF file iconPDF (526 KB)  
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  • Overvoltage counter for distribution lines

    Publication Year: 1977 , Page(s): 565 - 566
    Save to Project icon | PDF file iconPDF (269 KB)  
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  • Influence of surge impedance of the connecting lead in response time measurement of u.h.v. damped capacitive voltage dividers

    Publication Year: 1977 , Page(s): 566 - 568
    Save to Project icon | PDF file iconPDF (309 KB)  
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  • Analysis and synthesis of dynamic systems via block-pulse functions

    Publication Year: 1977 , Page(s): 569 - 571
    Cited by:  Papers (19)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (314 KB)  

    The paper presents a method of numerically integrating a system of differential equations based on an idea of orthogonal approximation of functions. Here, block-pulse functions are chosen as the orthogonal set. The method gives piecewise constant solutions with minimal mean-square error and is computationally similar to the familiar trapezoidal rule of integration. Design of piecewise constant controls or feedback gains for dynamic systems can be simplified following this approach. View full abstract»

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  • Lynch-Ayers microwave dielectric loss bridge for use over a range of temperatures

    Publication Year: 1977 , Page(s): 572 - 574
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (379 KB)  

    Precision measurements of losses in low-loss liquid dielectrics at microwave frequencies may be performed by means of a bridge method described by Lynch and Ayers. The paper describes modifications to such a bridge in order that measurements may be made over a range of temperatures. Results are presented for the temperature variation of loss angle at X-band in two very low-loss materials (cyclohexane and cycloheptane). The errors arising in the measurements are analysed; the overall likely error in the determination being ±(1¿rad or 2.4%). View full abstract»

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  • Assessment of random and systematic errors in microwave and submillimetre dielectric measurements

    Publication Year: 1977 , Page(s): 575 - 577
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    By considering the variation between runs comprising a given experiment, between the average results of independent experiments and between the extrapolated results of different experimental methods, some assessment of the systematic and random errors to be expected in high-frequency dielectric measurements is obtained. The liquid investigated is chlorobenzene as this has good chemical properties, possesses a rigid molecule and has been extensively investigated over a wide frequency range by other workers. Our results show that the random errors are frequency dependent but have average values of ±1.5% for ¿ and ±0.1% for n but that the systematic errors may reach as much as ± 3% for ¿ and ± 0.6% for n in the difficult regions. By combining data over a wide frequency range one may arrive at continuous curves whose estimated errors are ±1% for ¿ and ±0.2% for n. View full abstract»

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  • Simulation of transient and steady-state magnetisation characteristics with hysteresis

    Publication Year: 1977 , Page(s): 578 - 582
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (485 KB)  

    A simulation technique is described to generate both transient and steady-state B/H characteristics including hysteresis. The basic linear model is defined by three constant parameters, and, by refining these parameters to be nonlinear functions, the accuracy of representation is then improved. Additional features to improve the modelling technique for recoil characteristics are discussed. Good agreement was obtained between predicted and measured values for a wide range of materials. View full abstract»

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  • Influence of surface coating on transverse magnetostriction in silicon iron

    Publication Year: 1977 , Page(s): 583 - 585
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (502 KB)  

    Samples of grain-oriented 3¿% silicon iron have been tested for magnetostriction when magnetised at 90° to the rolling direction, and the effects of tensile stress have been observed. These tests were performed on coated and decoated samples, and included the effect of magnetic annealing. From variations in magnetostriction, an assessment has been made of the internal stresses in the materials, and a stress equivalent for magnetic annealing has been deduced. The influence of the coating has been considered in the light of the various stresses which it sets up, both on the magnetostriction and magnetic-annealing processes. A comparison has been made of the differing contributions of the coating to the performance of conventional and highly oriented silicon iron. 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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