Browsing Mathematics and Statistics by Issue Date

Now showing items 1-20 of 79

Impedance boundary condition in the boundary element-vector potential formulation

Subramaniam; Srisivane; Hoole, S; Ratnajeevan, H (1988-11)

The impedance boundary condition has been used with great profit to eliminate large regions from the solution to solve eddy current problems. In the boundary element formulation, the reduction of the order of singularities ...
A scheme for the implementation of implicit Runge-Kutta methods

Cooper, G.J; Vignesvaran, R (Springer-Verlag, 1990-12)

The computational work required to implement implicit Runge-Kutta methods is often dominated by the cost of solving large sets of nonlinear equations. As an alternative to modified Newton methods, iteration schemes, which ...
Two requisite tools in the optimal design of electromagnetic devices

Subramaniam; Srisivane; Kanaganathan, S; Hoole, S; Ratnajeevan (1991-09)

The requisite methodology for performing optimal design--the synthesis of devices from specified performance standards--is now in place. Software that is reliable and transparent to the user is required. If this could be ...
Singularly perturbed linear boundary value problems

Kathirkamanayagan, M; Ladde, G.S (1992-08)

In this paper an alternative approach to the method of asymptotic expansions for the study of a singularly perturbed linear system with multiparameters and multiple time scales is developed. The method consists of developing ...
Some schemes for the implementation of implicit Runge-Kutta methods

Cooper, G.J; Vignesvaran, R (1993-04)

The nonlinear equations, arising in the implementation of implicit Runge-Kutta methods, may be solved by a modified Newton iteration, but alternative iteration schemes have been suggested to reduce the linear algebra costs. ...
On the use of parallel processors for implicit Runge-Kutta methods

Cooper, G.J; Vignesvaran, R (Springer-Verlag, 1993-06)

An iteration scheme, for solving the non-linear equations arising in the implementation of implicit Runge-Kutta methods, is proposed. This scheme is particularly suitable for parallel computation and can be applied to any ...
Improving Rates of Convergence of Iterative Schemes for Implicit Runge-Kutta Methods

Vigneswaran, R. (Springer-Verlag, 1993-06-13)

Various iterative schemes have been proposed to solve the non-linear equations arising in the implementation of implicit Runge-Kutta methods. In one scheme, when applied to an s-stage Runge-Kutta method, each step of the ...
Matrix D.G. Near-rings

Tharmaratinam, V (1998)

Matrix near-rings had been defined by Meldrum and Van der Walt in 1986 and although a fair amount of results on the structure of these near-rings have been obtained since then, a satisfactory structure theory has yet to ...
Strong invariant approximation property for discrete groups

Kannan, K (Academic Publications, Ltd, 2003)

Let G be a countable exact discrete group. We show that G has the approximation property if and only if C* u(G, S) G = Cλ(G) ⊗ S for any Hilbert space H and closed subspace S ⊆ H, we have where C* u(G) is the uniform Roe ...
Phase Space Stability Error Control with Variable Time-stepping Runge-Kutta Methods for Dynamical Systems

Humphries, T.; Vigneswaran, R. (Wiley, 2004-12)

We consider a phase space stability error control for numerical simulation of dynamical systems. We illustrate how variable time-stepping algorithms perform poorly for long time computations which pass close to a fixed ...
Erroneous intracranial pressure measurements from simultaneous pressure monitoring and ventricular drainage catheters

Birch, A.A; Eynon, C.A; Schley, D (Humana Press Inc, 2006-08)

The objective of this report is to highlight the potential for false pressure measurements from systems that combine intracranial pressure (ICP) measurement and ventricular drainage. If the ports of the drain become blocked ...
Dynamics of a structured slug population model in the absence of seasonal variation

Bees, M.A; Angulo, O; López-Marcos, J.C; Schley, D (World Scientific Publishing Company, 2006-12)

We develop a novel, nonlinear structured population model for the slug Deroceras reticulatum, a highly significant agricultural pest of great economic impact, in both organic and non-organic settings. In the absence of ...
Development of a benchmark problem and a general optimisation package with Powell's method to develop the benchmark

Hoole, S.R.H; Udawalpola, R; Wijesinghe, K.R.C (Elsevier B.V., 2007-01)

Several methods of optimisation exist. Which method to use and under what circumstances is a difficult issue. A proper study requires a benchmark problem with known characteristics on which various methods and different ...
A new language for electromagnetic knowledge specification

Hoole, S.R.H; Mascrenghe, A; Navukkarasu, K (Elsevier B.V., 2007-01)

Knowledge specification languages are used in the design of electromagnetic and other products. But these, traditionally used to represent knowledge, do not exploit the full features of object-oriented programming and lack ...
Unified global optimality conditions for smooth minimization problems with mixed variables

Jeyakumar, V; Srisatkunarajah, S; Huy, N.Q (EDP Sciences, 2008-07)

In this paper we establish necessary as well as sufficient conditions for a given feasible point to be a global minimizer of smooth minimization problems with mixed variables. These problems, for instance, cover box ...
Lagrange multiplier necessary conditions for global optimality for non-convex minimization over a quadratic constraint via S-lemma

Jeyakumar, V; Srisatkunarajah, S (Springer-Verlag, 2009-01)

In this paper, we present Lagrange multiplier necessary conditions for global optimality that apply to non-convex optimization problems beyond quadratic optimization problems subject to a single quadratic constraint. In ...
New sufficiency for global optimality and duality of mathematical programming problems via underestimators

Jeyakumar, V; Srisatkunarajah, S (Springer Science+Business Media, LLC, 2009-02)

We present new conditions for a Karush-Kuhn-Tucker point to be a global minimizer of a mathematical programming problem which may have many local minimizers that are not global. The new conditions make use of underestimators ...
Geometric conditions for Kuhn-Tucker sufficiency of global optimality in mathematical programming

Jeyakumar, V; Srisatkunarajah, S (2009-04)

We present geometric criteria for a feasible point that satisfies the Kuhn-Tucker conditions to be a global minimizer of mathematical programming problems with or without bounds on the variables. The criteria apply to ...
A note on sufficient global optimality conditions for fixed charge quadratic programs

Jeyakumar, V; Srisatkunarajah, S (Elsevier Ltd, 2009-07)

In this work we establish conditions for a feasible point to be a global minimizer of a fixed charge quadratic model program. This program has a wide variety of classic applications, for instance, in facility location, ...
New Kuhn-Tucker sufficiency for global optimality via convexification

Jeyakumar, V; Lee, G.M; Srisatkunarajah, S (Elsevier Ltd, 2009-07)

In this paper, we first establish that the Kuhn-Tucker necessary optimality condition is sufficient for global optimality of the class of convexifiable programming problems with bounds on variables for which a local minimizer ...

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