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Electrical Engineers, Proceedings of the Institution of

Issue 1 • Date January 1972

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Displaying Results 1 - 19 of 19
  • Inaugural address. Computers and the professional engineer

    Publication Year: 1972
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (4359 KB)  

    The rapidly increasing population in most parts of the world is making most countries more and more dependent on technological development. There is, therefore, a most urgent need to find means of making engineering systems more economical in the use of raw materials and natural resources, easier to control and operate, simpler and more reliable. This calls for ingenuity based on a better understanding of the principles involved in these complex systems, and for just as much creativity and probably better engineering judgment than does the development of bigger and better systems. The challenge to the IEE at the start of its second 100 years is therefore to ensure that its members have the education and training to make them resourceful in emergencies, experience wide enough to have critical judgment and the determination to combat inefficiency wherever it may be. The development of computers is described in the paper to illustrate this need. Powerful and inexpensive computers with large data banks and a supporting data-transmission network should open up wonderful new opportunities for professional engineers. Computer-aided-design techniques should allow professional engineers to spend more time on creative work. The young engineer will be able to call on the designs of his predecessors, held in data banks, and to use his ingenuity to modify these in the light of new techniques and materials. Simulation methods enable a designer to test the performance of his designs quickly, and so he can try out many different designs in a few days instead of years. Provided that he is a good learner, therefore, he can gain experience very quickly indeed. It should therefore be possible to modify our engineering education to avoid the tedium of having to learn formulas and facts by rote, and, instead, to concentrate on an education which prepares engineers for a creative role in society. View full abstract»

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  • IEE Electronics Division: Chairman's address. Computer-aided design in electronics

    Publication Year: 1972 , Page(s): 17 - 27
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2266 KB)  

    The address reviews the development of computer-aided design (c.a.d.) in the last few years. In a historical introduction, the main characteristics of c.a.d. are outlined, particularly the use of interactive computing with time-sharing teletype keyboards or with c.r.t. graphics. The main applications to electronics are then reviewed, including device modelling, circuit analysis, network optimisation, logic simulation and general computing for local needs. The design of integrated circuits and their extensive use of computer aids are treated in more detail. Some less well established topics are then briefly touched on, particularly the possibilities of automatic layout of integrated and printed circuits and c.a.d. methods for large-systems design. The address continues with a section on equipment and software for c.a.d. and typical costs. It concludes with some comments on the present usefulness and limitations of c.a.d. and on trends for the immediate future. Batch processing will occupy a continuing role for large-scale calculations. The time-sharing teletype terminal is the most useful and flexible link to the computer for most applications. Interactive graphic displays are useful for layout tasks, but are still complex and expensive. View full abstract»

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  • Filter with periodic phase delay and insertion-loss ripple

    Publication Year: 1972 , Page(s): 28 - 32
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    An analytical design procedure is presented for the lowpass prototype selective linear phase filter, from which bandpass-channel filters may be deduced, whose insertion-loss and phase-delay-error functions vanish at an optimum number of equidistant points in the passband. Synthesis is performed using an even-and-odd-mode decomposition for a symmetrical filter comprising capacitors and impedance invertors. Finally, explicit formulas are given for element values in the 2nd-, 4th- and 6th-degree networks from which a simple realisability condition is deduced for all positive coupling elements, and numerical results on a 12th-degree filter are presented to illustrate the typical response characteristics. The main application of the design technique is in the construction of channel filters in high-capacity communication systems which use frequency modulation, particularly at microwave frequencies where the compact physical devices are readily constructed View full abstract»

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  • Review of methods for numerical solution of the hollow-waveguide problem

    Publication Year: 1972 , Page(s): 33 - 37
    Cited by:  Papers (14)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (923 KB)  

    A review is given of current methods for numerically solving the hollow-waveguide problem. Attention is drawn to the relative advantages of the various methods, particularly with regard to their performance with different waveguide shapes. Any requirement for a completely automatic algorithm, or for the computation of fields as well as cutoff values, is also found to put some methods to particular advantage. An attempt is made to compare and contrast the various formulations of finite-difference and finite-element methods (and other similar approaches) which result in a standard form of matrix-eigenvalue problem. Other methods studied are those of point-matching, integral equations and conformal transformations. View full abstract»

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  • Applicability of the Hansen-Woodyard condition

    Publication Year: 1972 , Page(s): 38 - 40
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    The Hansen-Woodyard condition is reviewed, and some of its various forms are discussed. For continuous arrays, the directivities for ordinary endfire and Hansen-Woodyard excitation are compared with the maximum obtainable directivity. Similarly, the directivities of discrete arrays, which are optimised with respect to the spacing under the above excitation constraints, are compared with the maximum obtainable directivity. It is concluded that, from a practical point of view, the Hansen-Woodyard condition yields results which are very close to the optimum, except for very short arrays. View full abstract»

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  • Intermodulation and a.m./p.m. distortion in f.m./f.d.m. radio systems during 2-path propagation

    Publication Year: 1972 , Page(s): 41 - 47
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (783 KB)  

    The total phase distortion on a path of an f.m./f.d.m. radio system under 2-path-propagation conditions consists of two components, intermodulation and amplitude/phase distortion which are not, in general, uncorrelated. It shown in the Appendix that the Taylor-series method of expanding a memoryless nonlinearity is, strictly, never valid in the case of 2-path propagation. The Fourier-series method of computing the path-intermodulation noise used previously is therefore extended to determine the power spectrum of the total phase-distortion noise. The analysis is confined to cases where the a.m./p.m.-conversion coefficient, expressed in degrees per decibel, is substantially constant and independent of frequency at low signal levels. Calculated results for total distortion noise in 1800- and 2700-channel systems are shown in the form of graphs which indicate that the values of the a.m./p.m. coefficient occurring in present receivers do not significantly degrade the system performance during 2-path propagation. View full abstract»

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  • Radiation by a dielectric-loaded cylindrical antenna with a wall airgap

    Publication Year: 1972 , Page(s): 48 - 54
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (713 KB)  

    Previous solutions for the radiation by a cylindrical antenna loaded with a single dielectric layer are extended to the multilayered case. For the sake of convenience, and without any loss of generality, only the 2-layered method of loading is considered by a boundary-value approach. Graphical results are presented to show the effect of the dielectric on the radiation pattern and conductance when the first layer is a thin air gap. It is shown that significant improvement in the pattern may be achieved with critical dimensions of the air gap. With a single or double layer, the dimensions may be selected to produce a broadside pattern similar to that of the unloaded dipole of less than half a wavelength. It is expected that this behaviour will be employed to improve the radiation characteristics when the antenna length is finite, provided that optimisation techniques are employed in designing the critical dimensions. View full abstract»

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  • Log-periodic transducers for acoustic surface waves

    Publication Year: 1972 , Page(s): 55 - 60
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (766 KB)  

    Nonuniform interdigital transducers, i.e. those in which the periodicity and aperture may vary, can be used to obtain a response not available from uniform transducers. Here, the log-periodic type, which is designed to give a large bandwidth, is investigated, and a bandwidth of 39% is achieved experimentally. Using certain assumptions, a simplified theory for nonuniform transducers is developed. The theory gives results in good agreement with the experiments. It is shown that it is necessary to profile the transducer if the passband ripple is to be minimised. View full abstract»

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  • IEE Power Division: Chairman's address. The shape of things to come

    Publication Year: 1972 , Page(s): 61 - 68
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1970 KB)  

    The design of electrical machines is almost entirely a problem concerned with shape. Some of our manufactured articles are the shape they are of necessity. Others may be designed in a variety of shapes within certain rules. For example, a drinking vessel must have at least one concave surface. But many other articles have stayed the same shape for generations purely by tradition. An engineer, who is primarily concerned with making inanimate objects, may be advised to study shapes found in Nature, to study the reason why one particular shape has evolved and then to ask himself seriously whether his products have really been designed or whether they have simply `evolved¿. Evolution in engineering means the result of an ever-changing sense of economic values, and often in the past we have, in effect, produced monstrosities by this process. An academic engineer may set himself the task of changing the shape of machines entirely for the sake of curiosity, and there is evidence that such an approach can lead to useful new commercial products. To `think shape¿ is often to think profitably. View full abstract»

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  • Civil-engineering works for a.c. electrification. Developments since 1960

    Publication Year: 1972 , Page(s): 69 - 73
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    An account is given of the change in conditions on British Railways during the period 1960¿1970 which have required developments in methods of achieving clearances for a.c. electrification. Relatively lightweight precast reinforced-concrete arch units have been developed for erection by off-track equipment to replace many existing arch bridges. Different techniques for individual bridges are also described. Experience in running has indicated that waterproofing is a very important factor, and this, together with parapet treatments, is reviewed. View full abstract»

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  • Calculation of gas pressures in oil-circuit-breaker arc-control pots

    Publication Year: 1972 , Page(s): 74 - 75
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  • Calculation of system-fault currents due to induction motors

    Publication Year: 1972
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  • Reply: Calculation of system-fault currents due to induction motors

    Publication Year: 1972 , Page(s): 75 - 76
    Cited by:  Papers (3)
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  • IEE Control & Automation Division: Chairman's address. Communications in control

    Publication Year: 1972 , Page(s): 77 - 82
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    Communications and control can be regarded as complementary components of an overall system, and there should be an adequate match between them at all interfaces. Communications degraded by noise, delays and interruptions can have adverse effects on control performance, but can be mitigated by the proper use of redundancy and by such operations as modelling, statistical filtering and prediction. Errors occurring at the source should be identified and allowed for. Illustrative examples include air navigation, the CEGB automatic-control experiment looked at in retrospect, and future trends in computer-aided command and control on the battlefield. In the last of these, the complexity of man-machine interactions brings special problems in design, in programming and in adapting the organisation to incorporate the new techniques with maximum effectiveness. View full abstract»

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  • Combined delay and loss common-control queuing system

    Publication Year: 1972 , Page(s): 83 - 87
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    The paper presents a detailed study of a combined delay and loss common-control queuing system which has a limited waiting capacity. The common-control queuing system considered is one with a Poisson input, first-come-first-served queue discipline and a negative exponential distribution for both the operating time of the common control and the service time of the server. The stationary-state probabilities of the system, the loss probability, the waiting probability and the waiting-time distribution function are obtained in explicit form. It is shown that, using the unified approach (the notion of combined delay and loss), the system studied includes the pure-delay and pure-loss systems as special cases. In addition, many results reported in the literature can be derived from those presented in the paper. View full abstract»

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  • Predictive model of an operator in a decision-making task

    Publication Year: 1972 , Page(s): 88 - 90
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    A model is described in the paper which simulates the behaviour of an operator in a decision-making task where successive decisions must be made at a faster rate as the task proceeds. The model has provided a possible explanation for the discrete-data nature of the human transfer function. View full abstract»

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  • Optimal control of synchronous-machine excitation by quasilinearisation techniques

    Publication Year: 1972 , Page(s): 91 - 98
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    This paper describes the application of quasilinearisation techniques in solving nonlinear optimal-control problems in power systems. The computational effectiveness of this method is demonstrated in controlling the excitation to optimise the performance of a synchronous machine simulated as a simple 3rd-order system. The results presented in this paper show that the application of quasilinearisation technique gives an accurate solution utilising considerably less computer time compared with the more commonly used gradient method. However, the core requirements for this method are greater than those for the gradient method. To examine the effects of the relative emphasis placed on the different state variables in the performance criterion, optimisation has been carried out with respect to two different quadratic indices. The usefulness of the quasilinearisation technique is further demonstrated by its application to an optimisation problem with practical constraints on the control variable. View full abstract»

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  • IEE Science, Education & Management Division: Chairman's address. Physics in the service of the engineer

    Publication Year: 1972
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2020 KB)  

    The exceptional periods when physics research readily led to innovations of vast consequence in engineering, such as the period of solid-state research which led to the transistor, have tended to obscure the valuable role of physics in providing steady support to technological development. In an attempt to redress the balance, the stress in this review has been placed on the evolutionary role of physics, as illustrated by examples drawn from a few selected fields. In lighting, assistance from materials science, discharge physics and optics has led to major improvements in the performance of lamps and associated equipment. The practicability of homopolar machines, where the principle dates back to Faraday's disc, depends to no small extent on progress made by physicists working closely with engineers in solving the slipring problem. Microwave radar ushered in a virtually new engineering field supported by a still widening range of solid-state and other components, of which gyromagnetic ferrites and special dielectrics are typical examples. Applicable over the whole of engineering are the physical methods of materials characterisation, such as X ray techniques and mass spectrometry, hitherto mainly operated by the specialist but now also moving into the hands of the engineer, for example, in process control and automation. A concluding look at the future outlines some of the newer developments in applied physics, especially in solid-state physics and optics, in relation to present and foreseeable engineering requirements. There is a final brief reference to the educational implications as more physicist-engineers take their place in the profession. View full abstract»

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  • Square-wave-source gated-detector bridge system for the precise measurement of resistance

    Publication Year: 1972 , Page(s): 108 - 112
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (645 KB)  

    The design and performance of a square-wave system for the precise measurement of resistance are described. A 25 Hz square wave is applied to a conventional resistance bridge, and the output of the bridge is sampled, after the decay of transients owing to reactances, by a gated detector. A single adjustment is sufficient to balance the bridge, and the balance is independent of thermal electromotive forces. The system is suitable for platinum-resistance thermometry, and a square-wave-to-d.c. error of less than 10 ¿¿ may be obtained in the resistance range 0¿100 ¿. 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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