Browsing by Author "Lucas, T. Nigel"
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Model reduction by condensed continuedfraction method
Lucas, T. Nigel (Institution of Engineering and Technology, 198508)It is shown how the continuedfraction method of Chen and Shieh may be used on part of the transfer function to produce reducedorder models when its normal application is unsatisfactory. In addition, the truncation method ... 
Model reduction by generalised leastsquares method
Lucas, T. Nigel; Munro, A. R. (Institution of Engineering and Technology, 199107)The method of model reduction by leastsquares 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 leastsquares moment matching
Lucas, T. Nigel; Beat, I. F. (Institution of Engineering and Technology, 199007)Model reduction by leastsquares 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 "welldefined" 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 wellknown 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 discretetime leastsquares Padé method
Lucas, T. Nigel (Sage Publications, 1999)It is shown that reduced order models produced by the leastsquares Padé method for discretetime 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, 199309)A discretetime multipoint Padé approximation method is presented that derives optimal reducedorder 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, 199301)A novel method of obtaining optimal reducedorder 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, 198808)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 ... 
Shiftandscale model reduction: an alternative stabilitypreserving approach
Lucas, T. Nigel (Sage Publications, 2004)A new stabilitypreserving model orderreduction method is presented for continuoustime systems. It makes use of the relatively new idea of transformed wholesystem 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, 199209)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 reducedorder models for discretetime systems
Lucas, T. Nigel (Institution of Engineering and Technology, 198701) 
Suboptimal discrete model reduction by multipoint Padé approximation
Lucas, T. Nigel (Elsevier, 199601)A multipoint Padé approximation method is presented for obtaining a reduced order ztransfer function, with a predetermined denominator, such that the squareerrorsum 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 reducedorder transfer function, with a predetermined denominator, such that the integral square error between the time responses ofthe full and reduced models is ... 
A tabular approach to the stability equation method
Lucas, T. Nigel (Elsevier, 199201)A tabular method for reducing polynomial degrees by the stability equation criterion is given. It is the consequence of an interesting multipoint Taylor polynomial approximation property which is shown to hold for the ... 
A unifying theory of least‐squares Padé model reduction methods
Smith, I. D.; Lucas, T. Nigel (Sage Publications, 1996)