Now showing items 26-45 of 47

  • Linear system reduction by continued-fraction expansion about three points 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1984-01)
    The method of model reduction by continued-fraction expansion about s = 0 and s = a is extended to include the point s = à ¿ also. This achieves more accurate transient approximations and thus highlights further the ...
  • 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 ...
  • 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 ...
  • Linear system reduction using Schwarz canonical form 

    Davidson, A. M.; Lucas, T. Nigel (Institution of Engineering and Technology, 1976-06)
    A system reduction method based on Schwarz canonical form has recently been observed to have certain moment-matching properties. By reformulating the method, these properties are proved and extended and the stability of ...
  • Linear-system reduction by continued-fraction expansion about a general point 

    Davidson, A. M.; Lucas, T. Nigel (Institution of Engineering and Technology, 1974-07)
    Capacity requirements for multiple-access demand-assigned communication systems are broken down into information, demand and assignment signalling. A simultaneous-transmission scheme for demand signalling greatly reduces ...
  • 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 ...
  • Model reduction by generalised least-squares method 

    Lucas, T. Nigel; Munro, A. R. (Institution of Engineering and Technology, 1991-07)
    The method of model reduction by least-squares moment matching is generalised to include Markov parameters in the process. This is seen to enhance the flexibility of the method with very little extra computational requirement. ...
  • 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 ...
  • New matrix method for multipoint Pade approximation of transfer functions 

    Lucas, T. Nigel (Taylor & Francis, 1993)
    A new way of formulating a multipoint Pad approximant of a linear system transfer function is given. It is seen to be very flexible and computationally efficient. The expansion points can be a mixture of real, complex, ...
  • 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 ...
  • A note on order reduction by the discrete-time least-squares Padé method 

    Lucas, T. Nigel (Sage Publications, 1999)
    It is shown that reduced order models produced by the least-squares Padé method for discrete-time systems can sometimes produce misleading results for step and polynomial inputs. A more representative way of deriving such ...
  • Optimal discrete model reduction by multipoint Padé approximation 

    Lucas, T. Nigel (Elsevier, 1993-09)
    A discrete-time multipoint Padé approximation method is presented that derives optimal reduced-order models. The method is seen to be easily implemented using a recently developed way of calculating Padé approximants. An ...
  • Optimal model reduction by multipoint Padé approximation 

    Lucas, T. Nigel (Elsevier, 1993-01)
    A novel method of obtaining optimal reduced-order models of linear system transfer functions is presented. It uses the popular multipoint Padé approximation technique in an iterative way to generate efficiently the optimal ...
  • 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 ...
  • Shift-and-scale model reduction: an alternative stability-preserving approach 

    Lucas, T. Nigel (Sage Publications, 2004)
    A new stability-preserving model order-reduction method is presented for continuous-time systems. It makes use of the relatively new idea of transformed whole-system parameter matching for calculating the poles of the ...
  • Some further observations on the differentiation method of modal reduction 

    Lucas, T. Nigel (Institute of Electrical and Electronics Engineers, 1992-09)
    The differentiation method of model reduction is shown to be equivalent to forming successive ratios of multipoint Taylor polynomial approximation of the numerator and denominator of the transfer function, respectively. ...
  • Stable reduced-order models for discrete-time systems 

    Lucas, T. Nigel (Institution of Engineering and Technology, 1987-01)
  • Sub-optimal discrete model reduction by multipoint Padé approximation 

    Lucas, T. Nigel (Elsevier, 1996-01)
    A multipoint Padé approximation method is presented for obtaining a reduced order z-transfer function, with a pre-determined denominator, such that the square-error-sum of time responses between the full and reduced models ...
  • Suboptimal model reduction by multi‐point Padé approximation 

    Lucas, T. Nigel (Sage Publications, 1994)
    A novel Pade approximation method is used to obtain a reduced-order transfer function, with a predetermined denominator, such that the integral square error between the time responses ofthe full and reduced models is ...