Now showing items 21-40 of 2014

  • Linear system reduction by impulse energy approximation 

    Lucas, T. Nigel (Institute of Electrical and Electronics Engineers, 1985-08)
    A method is given for linear system reduction which is a more general form of the Routh method. The reduced models retain stability, and a fuller contribution is made to the impulse response energy of the reduced system ...
  • Model reduction by condensed continued-fraction method 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1985-08)
    It is shown how the continued-fraction method of Chen and Shieh may be used on part of the transfer function to produce reduced-order models when its normal application is unsatisfactory. In addition, the truncation method ...
  • Magnesium and cell cycle control: an update. 

    Walker, Graeme M. (Karger, 1986)
    Accumulating evidence, from bacteria to human cells, points to a universal role for magnesium in controlling the cell cycle. In microorganisms, the co-ordinate sequence of events which culminate in biomass doubling and ...
  • Continued-fraction expansion about two or more points: a flexible approach to linear system reduction 

    Lucas, T. Nigel (Elsevier, 1986-01)
    Model reduction by continued-fraction expansion about two or more points, including the general point s = a, is shown to be a real alternative to the methods which guarantee stability. Suitable choice of a is seen to ...
  • Linear system reduction by the modified factor division method 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1986-11)
    A novel method of linear system simplification is presented based on a modified factor division approach. It is seen to be more flexible than most model reduction methods in that families of reduced models may be easily ...
  • Stable reduced-order models for discrete-time systems 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1987-01)
  • Further discussion on impulse energy approximation 

    Lucas, T. Nigel (Institute of Electrical and Electronics Engineers, 1987-02)
    Recent criticisms by Rao about impulse energy approximation are answered in detail. Further ideas are put forward as to how weighted energy parameters may be used to determine the reduced models for step inputs.
  • Comment: Taylor series approach to functional approximation for inversion of Laplace transforms 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1987-02)
  • Differentiation reduction method as a multipoint Pade approximant 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1988-01)
    The differentiation method for model order reduction is shown to be a special case of multipoint Pade approximation. This link also extends to other reduction methods where reduced models are generated successively. An ...
  • Scaled impulse energy approximation for model reduction 

    Lucas, T. Nigel (Institute of Electrical and Electronics Engineers, 1988-08)
    It is shown that the impulse energy approximation technique for model reduction can be improved by scaling in the frequency domain. The method remains simple to use and retains the stability property of impulse energy ...
  • Evaluation of scalar products of repeated integrals by Routh algorithm 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1988-09)
    It is shown that evaluation of Gram matrix entries for model reduction information may be carried out by repeated use of the well known Routh algorithm. This procedure is seen to enhance both the understanding and ...
  • Induction of a heat shock-type response in fission yeast following nitrogen starvation 

    Walker, Graeme M.; McWilliams, Philip G (Wiley-Blackwell, 1989)
    When cells of the fission yeast, Schizosaccharomyces pombe, are incubated in medium devoid of a nitrogen source, they accelerate into cell division and differentially synthesize two polypeptides at 46 and 27 kD (named p46 ...
  • New results on relationships between multipoint Pade approximation and stability preserving methods in model reduction 

    Lucas, T. Nigel (Taylor & Francis, 1989)
    Three well-known stability preserving methods of reduction are shown to be special forms of the multipoint pade approximation. Two of the methods—the modified forms of the Schwarz approximation and the stability equation ...
  • Comment on 'biased model reduction by simplified Routh approximation method' 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1989-10)
    For the original article see ibid., vol.23, p.1045-7 (1987). Sastry and Krishnamurthy recently suggested a 'simplified' Routh approximation method (SRAM) for model order reduction of linear systems. They claim that one of ...
  • The importance of magnesium ions in yeast biotechnology 

    Walker, Graeme M.; Maynard, A. Ian; Johns, Colin G. W. (Elsevier Applied Science, 1990)
  • Finding roots by deflated polynomial approximation 

    Lucas, T. Nigel (Elsevier, 1990)
    A numerical technique is presented which evaluates the roots of polynomials with real coefficients. Features of the method include no complex arithmetic requirements, no need to guess at initial quadratic factor estimates, ...
  • Microbial aspects of sewage and sewage sludge in Dundee, Scotland 

    Jefferies, Christopher; Young, H. K.; McGregor, I. (IWA Publishing, 1990)
    Studies of the populations of coliforms and faecal streptococci in sewage and sewer sediments have been carried out in Dundee. Samples have been obtained and tested by standard methods from five storm and five dry weather ...
  • The quality of sewage flows and sediment in Dundee 

    Ashley, R. M.; Coghlan, B. P.; Jefferies, Christopher (IWA Publishing, 1990)
    Inter-related studies are underway in Dundee to investigate the nature, origins, disposition and movements of sewer sediments and associated pollutants. These studies, funded mainly by the Water Research Centre, have ...
  • Model reduction by least-squares moment matching 

    Lucas, T. Nigel; Beat, I. F. (Institution of Engineering and Technology, 1990-07)
    Model reduction by least-squares moment matching is shown to be very sensitive to the pole distribution of the original system. Systems with poles of modulus less than unity are seen to present numerical problems. A ...
  • Modelling an athletics track 

    Lucas, T. Nigel (Oxford University Press, 1991)
    When introducing students to mathematical modelling ideas it is often useful to have them tackle a fairly "well-defined" problem, possibly related to an outside interest, involving the use of traditional mathematical ...