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Volume 126
Issue 6
Proceedings of the Institution of Electrical Engineers
Volume 126, Issue 6, June 1979
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Volume 126 (1979)

Volume 125 (1978)

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Volume 126, Issue 6
June 1979

 Author(s): H.W. Thomas
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 469 –475
 DOI: 10.1049/piee.1979.0113
 Type: Article
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This paper describes an approach to the detection of turns in a radar tracking system and discusses some of the difficulties encountered in a multiradar system when using more conventional manoeuvre detectors with αβ or Kalman filter trackers. Typical aircraft tracks are presented to illustrate the improvements possible using the approach described.  Author(s): D.C. Cooper
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 476 –480
 DOI: 10.1049/piee.1979.0114
 Type: Article
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p.
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A 2axis sumanddifference monopulse radar incorporating a signal processor which is close to optimum is considered to operate in an environment consisting of a Rayleigh fluctuating target and an arbitrary spatial distribution of fluctuating sources of clutter and intereference or jamming. The bivariate probability density function for the system indications, one for each axis, is derived and some examples of monopulse operation are considered.  Author(s): G.F. Gott and B. Hillam
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 481 –486
 DOI: 10.1049/piee.1979.0115
 Type: Article
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p.
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An f.s.k. signal keyed at 75 bauds with 850 Hz frequency shift, can have one of several frequency allocations within any given h.f. voice channel. In the presence of interference from other users, the f.s.k. system performance may be improved by choosing the f.s.k. tone frequencies before message transmission, to correspond to frequencies within the voice channel where the interference is least. This paper reports on an 800 km pointtopoint h.f. link experiment which investigated this principle, combined with forward errorcorrecting codes, with the aim of improving aeromobile data transmission.  Author(s): S.W. Lee ; E. Yung ; R. Mittra
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 487 –492
 DOI: 10.1049/piee.1979.0116
 Type: Article
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p.
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The input admittance of an elemental radiator on a curved surface, e.g. a slot on a cone, plays an important role in the design of conformal arrays. A search through the literature reveals that, at present, there is no reliable theoretical method available for computing this admittance. The objective of this paper is to provide a solution to this problem using a surfaceray approach–within the framework of g.t.d. The solution is verified for the limiting case where the cone degenerates into a cylinder, and it is shown that the g.t.d. results compare extremely well with the exact modal solution to the cylinder problem. Extensive numerical results are presented in the paper for the input admittance of a cone as a function of various design parameters.
Manoeuvre handling in a multiradar a.t.c. system
Probability density function for the indications of a 2axis monopulse radar operating in the presence of system noise, clutter and interference
Improvement of slowrate f.s.k. by frequency agility and coding
G.T.D. solution of slot admittance on a cone or cylinder

 Author(s): J. Arrillaga and R.M. Duke
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 493 –498
 DOI: 10.1049/piee.1979.0117
 Type: Article
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With reference to the conventional quadrature booster transformer, this paper describes a way of achieving continuous phaseshift control based on pointonwave thyristor switching. The proposed unit can provide continuous and practically instantaneous powertransfer control in transmission circuits. The theoretical waveforms are verified by experimental tests and computer studies. Consideration is also given to the harmonic content produced.  Author(s): S.K. Salman and R.N. Allan
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 499 –505
 DOI: 10.1049/piee.1979.0118
 Type: Article
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499
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The economy of u.h.v. lines is of such importance that it is essential to select the parameters which decide its cost in a most careful way. Therefore, the application of optimisation techniques to the design of a transmission line has been considered. A nonlinear algorithm, using the concept of n.l.p. algorithm, and a mathematical representation of the line have been developed.  Author(s): F. Donazzi ; E. Occhini ; A. Seppi
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 506 –516
 DOI: 10.1049/piee.1979.0119
 Type: Article
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In the present paper, the thermal and hydrological characteristics of the soil surrounding buried cables are investigated. First, the dependence of the soil thermal resistivity on two easily measurable parameters is shown. These parameters are the porosity and the saturation degree. The soil hydrological stability is then investigated and is found to be governed by one hydrological parameter only; namely, the saturation degree. Finally, the conditions governing soil hydrological equilibrium are investigated, which appear to be dependent both on the initial soil saturation degree and on the applied thermal gradient (i.e. on the thermal flow). In principle, on the basis of this simple information, it is possible to carry out a rational design of a buriedcables system preventing any hydrological instability.  Author(s): G.J. Berg ; P. Subramanian ; K.R.C. Mamandur
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 517 –519
 DOI: 10.1049/piee.1979.0120
 Type: Article
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The summary discusses the computational aspects and requirements of load flow solution methods. In particular, new piecewise solution technique is considered. In the new algorithm, based on the NewtonRaphson method, the Jacobian is block diagonalised according to chosen subsystems, and the voltage correction vectors of the respective subsystems are solved independently. The effects of interconnections are taken into account using a method of successive approximation. The memory and computational requirements of the new technique are discussed and compared with those of the onepiece solution. The computational requirements are indicated analytically, facilitating examination of the effects of tearing. The number of subdivisions required to minimise computing effort is also indicated.  Author(s): C.S. Indulkar and S. Thiruvengadam
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, page: 519 –519
 DOI: 10.1049/piee.1979.0121
 Type: Article
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 Author(s): D.J. Wilcox
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 519 –520
 DOI: 10.1049/piee.1979.0122
 Type: Article
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p.
519
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 Author(s): L.S. Cornish and S.K. Tso
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 520 –521
 DOI: 10.1049/piee.1979.0123
 Type: Article
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 Author(s): P. Vas
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, page: 522 –522
 DOI: 10.1049/piee.1979.0124
 Type: Article
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 Author(s): K. Manickam and R. Srinivasan
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, page: 522 –522
 DOI: 10.1049/piee.1979.0125
 Type: Article
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 Author(s): K. Manickam and R. Srinivasan
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, page: 523 –523
 DOI: 10.1049/piee.1979.0126
 Type: Article
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Thyristorcontrolled quadrature boosting
Application of optimisation techniques to the design of veryhighvoltage power lines
Soil thermal and hydrological characteristics in designing underground cables
Performance and computational requirements of new piecewise load flow algorithm
Transient analysis and performance of crossbonded cable systems
Reply: Transient analysis and performance of crossbonded cable systems
Use of triacs in naturally commutated cycloconvertors
Plugging of capacitor motors
Reply: Plugging of capacitor motors
Erratum: Plugging of capacitor motors

 Author(s): D.H. Owens
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 525 –530
 DOI: 10.1049/piee.1979.0127
 Type: Article
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p.
525
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The concept of an m×m invertible continuous firstorder lag is extended to define an equivalent formulation for multivariable sampleddata systems. A large class of proportionalplussummationoutput feedback controllers is constructed. Each controller guarantees the stability of the closedloop system and, also, lowclosedloop interaction effects if the sampling rate is high enough. The results are extended to show that a multivariable discrete firstorder lag is, in many cases of practical interest, a quite adequate approximation for the purpose of controller design provided that the plant is minimum phase and satisfies a contractionmapping condition. In particular, any discrete model of a minimumphase continuous linear timeinvariant plant with a nonsingular value of CB will satisfy the contraction condition provided that the sampling rate is high enough.
Discrete firstorder models for multivariable process control

 Author(s): I. Ishii and T. Noguchi
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 532 –536
 DOI: 10.1049/piee.1979.0128
 Type: Article
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p.
532
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The paper reports the results of an experimental investigation into the dielectricbreakdown behaviour of supercritical helium, in the range from 4.2 to 30 K and 0.4 to 1.5 MPa under d.c., a.c. and standard impulse voltages, to assist the development of superconducting power cables. At helium densities above 80 kg m^{−3}, the uniformfield breakdown voltage for d.c. or a.c. is about 55 MV m^{−1} at 0.8 MPa and has a slight pressure dependence. In nonuniform fields, the breakdown voltage with a negative electrode is considerably increased by corona stabilisation in the density range from 30 to 83 kg m^{−3}.
Dielectric breakdown of supercritical helium

 Author(s): C.J. Harris and D.H. Owens
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, page: 537 –537
 DOI: 10.1049/piee.1979.0129
 Type: Article
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 Author(s): D.H. Owens
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 538 –541
 DOI: 10.1049/piee.1979.0130
 Type: Article
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p.
538
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By regarding system compensation as the manipulation of the asymptotic directions and pivots of the root locus of the closedloop multivariable system, the paper describes a general framework for the construction of forward path and minor loop compensation elements for a square, invertible plant with a transferfunction matrix G(s). The approach is based on the use of dynamic transformations of G and the properties of the inverse plant G^{−1}.  Author(s): B.A. Kouvaritakis
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 542 –548
 DOI: 10.1049/piee.1979.0131
 Type: Article
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p.
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Recent work on the application of complexvariable theory to the analysis of linear multivariable systems has led to a design philosophy that integrates the frequencyresponse and the rootlocus approach. A brief discussion of the 2stage design technique that derives from this philosophy is first undertaken, and its application to a 3input/3output model of a oncethrough boiler is considered. On the face of lack of excess measurements an outerloop design study only is carried out where frequencyresponse techniques are employed for the adjustment of the openloop characteristic properties of the system. Through the use of the approximately commutative controller, it is shown that it is possible to gain/phase compensate the system characteristic gain using classical lead/lag and proportional plus integral controllers. The overall control scheme results in a system whose response is fast, nonoscillatory, accurate in the steady state and largely nonovershooting and noninteractive.  Author(s): N. Munro
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 549 –554
 DOI: 10.1049/piee.1979.0132
 Type: Article
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549
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The problem of pole assignment using state feedback or output feedback is examined. A new algorithm for the design of fullrank minimum degree outputfeedback compensators is presented, and results in a unification of previously obtained results.  Author(s): I. Postlethwaite
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 555 –562
 DOI: 10.1049/piee.1979.0133
 Type: Article
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p.
555
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The ‘characteristic locus design method’ is essentially a complexvariable approach, which relies heavily on algebraicfunction theory for its rigorous foundation. In the paper, a summary is given of results developed during the past three years from an algebraicfunction theoretic approach to the analysis of multivariable feedback systems.  Author(s): D.H. Owens
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 563 –567
 DOI: 10.1049/piee.1979.0134
 Type: Article
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p.
563
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This is an expository paper devoted to surveying and explaining some of the basic concepts required, and the motivations for, the definition and use of dyadic expansions in systems analysis and controller design. Where possible, the material is related to the inverse Nyquist array and characteristic locus design methods.  Author(s): D.Q. Mayne
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 568 –572
 DOI: 10.1049/piee.1979.0135
 Type: Article
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p.
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The paper describes and critically assesses, in the light of recent advances, the sequential return difference method for the computeraided design of linear multivariable control systems. In this method, a sequence of singleloop designs, using classical procedures, yields a multivariable design satisfying various criteria such as stability, disturbance attenuation, low interaction and integrity.  Author(s): R.G. Becker ; A.J. Heunis ; D.Q. Mayne
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 573 –578
 DOI: 10.1049/piee.1979.0136
 Type: Article
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p.
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The paper describes a computeraideddesign procedure which may be used to design, inter alia, multivariable control systems which satisfy constraints on peak overshoot of step response on control magnitudes, control rates and on states, as well as conventional constraints.  Author(s): V. Zakian
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 579 –584
 DOI: 10.1049/piee.1979.0137
 Type: Article
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p.
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A new version of the method of inequalities is developed for the design of feedback control systems that have nonlinear and multivariable characteristics and are subject to disturbances. The system is required to behave in accordance with a criterion which takes the form of a prescribed bound on each component of the error vector.  Author(s): N. Karcanias
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 585 –590
 DOI: 10.1049/piee.1979.0138
 Type: Article
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p.
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A number of relationships between the geometric and the algebraic linear system theory are briefly surveyed, which may be discussed in terms of the classical theory of matrix pencils. The inputoutput pencil is defined and used for the characterisations of the geometrical concepts of (A, B)invariant subspace, controllability subspace and transmission subspace. The problem of finding the maximal (A, B)invariant and maximal controllability subspaces contained in another subspace is finally reduced to a problem of analysing the structure of a particular pencil, the restriction pencil. A common theme running through all the analyses is the use of the canonical forms of Weierstrass and Kronecker.  Author(s): M.J. Denham and A.I.G. Vardulakis
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 591 –595
 DOI: 10.1049/piee.1979.0139
 Type: Article
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p.
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The design of controllers for multivariable systems, in particular largescale systems, requires knowledge and exploitation of the structural properties of the systems. The ability to achieve certain structural properties, e.g. regulation, tracking, noninteraction, disturbance, rejection etc., can be determined on the basis of a small number of basic system concepts. In this paper, structural decomposition of a multivariable system is studied using the concept of a controllability subspace, and a review of recent work to investigate this concept is given.  Author(s): K. Glover
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 596 –604
 DOI: 10.1049/piee.1979.0140
 Type: Article
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p.
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The problem of approximate realisation is described and various methods are discussed. A new method is then given which directly identifies the system poles from pulse response data by finding the local minima of a real function of a complex variable. These estimates of the poles are then refined using a new iterative nonlinear leastsquares algorithm. Finally, these methods are applied to a ‘seismic wavelet’, and are shown to give good qualitative and quantitative information on the system being modelled.  Author(s): P.E. Crouch
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 605 –615
 DOI: 10.1049/piee.1979.0141
 Type: Article
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The paper is concerned with certain aspects of modelling dynamical systems. This problem can be divided into two parts; first, there is the question of identifying the system structure, and secondly of identifying the parameters defining the structure. Realisation theory provides a framework in which models of dynamical systems can be analysed mathematically, and in particular affects the structural identification problem. This paper is an expository paper devoted to surveying the main results. Three main areas are treated, those of linear, bilinear and nonlinear systems, providing a natural progression of technique and applicability. The complexities of the nonlinear theory have been minimised as far as possible, so that the results can be applied with a limited knowledge of calculus and algebra. Examples on Hamiltonian and polynomic systems are included to show how realisation theory is used in structural identification.  Author(s): P.A. Cook
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 616 –622
 DOI: 10.1049/piee.1979.0142
 Type: Article
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p.
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The paper gives a selective review of the results obtained by applying the methods of functional analysis to stability problems in dynamical system theory.  Author(s): J.M.E. Valenca and C.J. Harris
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 623 –627
 DOI: 10.1049/piee.1979.0143
 Type: Article
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p.
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In the paper, multivariable input/output stability criteria of a graphical nature for nonlinear multivariable feedback systems are developed. The derived stability criteria, which are of the circle type, use the frequency plots of the eigenvalues of a normal transferfunction matrix which approximates the linear part of the nonlinear feedback system. An iterative design procedure is introduced which reduces the error of approximation and the feedback systems sensitivity to disturbances, while ensuring the stability of the closedloop system.  Author(s): A.I. Mees and D.J. Allwright
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 628 –632
 DOI: 10.1049/piee.1979.0144
 Type: Article
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p.
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The Hopf bifurcation theorem is used by physicists, biologists and others interested in oscillations in systems described by differential equations. This paper presents a version of the theorem applicable directly to feedback systems, using the method of characteristic loci in an interpretation which looks rather like a multipleloop version of the graphical describing function method. Frequency, amplitude and stability of oscillations about an equilibrium state are predicted by an iterative process which starts with a 2ndorder harmonic balance and successively increases the number of harmonics taken into account. The results from each stage of the process are used to define a curve in the complex plane from which the results of the next stage can be read off; consequently, the user has a visual indication of the accuracy and rate of convergence. The main theoretical limitation is that the nonlinear elements in the system must be continuously differentiable at least once more than the order of the highest harmonic used, whereas the main practical limitation is that the formula for the curve becomes extremely complicated if more than about six harmonics are considered.  Author(s): D.W. Clarke and P.J. Gawthrop
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 633 –640
 DOI: 10.1049/piee.1979.0145
 Type: Article
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Self tuning is an important new branch of control which is attracting increasing theoretical and practical interest. The objective of self tuning is to control systems with unknown constant or slowly varying parameters, so theoretical interest is concerned with the stability, performance and convergence of the recursive algorithms involved, while practical interest derives from its potential as a simple controller commissioning tool, both as a method for controlling timevarying or nonlinear plant over a range of operating points, and for dealing with batch problems where the plant or materials vary over successive batches. This paper summarises and expands previous work on the design of selftuning controllers. It discusses the closedloop properties of various classes of self tuner, convergence concepts and results, and some of the technical problems involved with implementing self tuners on small computers or microprocessors.  Author(s): A.J. Pritchard
 Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 6, p. 641 –648
 DOI: 10.1049/piee.1979.0146
 Type: Article
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p.
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The paper considers some control problems for systems described on infinitedimensional spaces. A mathematical framework in terms of semigroups is developed which enables the generalisation of the finitedimensional results to infinite dimensions, and which includes partial differential equations and delay equations as special cases. After first surveying some finitedimensional results, abstract dynamical systems are introduced and the systems theory concepts of stability, controllability, observabiity and the linear quadratic problem are analysed. Throughout the paper the abstract theory is applied to a number of examples to obtain specific results.
Editorial
Compensation theory of multivariable root loci
Theory and practice of the characteristic locus design method
Pole assignment
Algebraicfunction theory in the analysis of multivariable feedback systems
Dyadic expansions and their applications
Sequential design of linear multivariable systems
Computeraided design of control systems via optimisation
New formulation for the method of inequalities
Matrix pencil approach to geometric system theory
Structural properties of multivariable linear systems
New techniques for approximate realisation
Realisation theory for dynamical systems
Circle theorems and functional analytic methods in stability theory
Stability criteria for nonlinear multivariable systems
Using characteristic loci in the Hopf bifurcation
Selftuning control
Infinitedimensional linearsystems theory
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