Tuesday, May 24. 2011
M.K. Kadalbajoo and A.S.Yadaw2 Department of Mathematics and Statistics, Indian Institute of Technology Kanpur, Kanpur 208016, India Received 9 December, 2009; accepted in revised form 20 December, 2010 Abstract: The objective of this paper is to present a comparative study of fitted-mesh finite difference method, Ritz-Galerkin finite element method and B-spline collocation method for a two-parameter singularly perturbed boundary value problems. Due to the small parameters ϵ and μ, the boundary layers arise. We have taken a piecewise-uniform fittedmesh to resolve the boundary layers and shown that fitted-mesh finite difference method has almost first order parameter-uniform convergence, Ritz-Galerkin finite element method has almost second order parameter-uniform convergence and B-spline collocation method has second order parameter-uniform convergence. Numerical experiments support these theoretical results.
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Tuesday, May 24. 2011
Gloria Cravo2 Centro de Ciˆencias Exactas e da Engenharia, Universidade da Madeira, 9000-390 Funchal, Madeira, Portugal Received 17 January, 2009; accepted in revised form 14 December, 2010 Abstract: In this paper we present a new formalism to study the structure of workflows. A workflow is an abstraction of a business process that consists of one or more activities that need to be executed to reach a final objective. Our formalism is based on Graph Theory, Propositional Logic, and Boolean matrices. Indeed, we model workflows with tri-logic acyclic directed graphs. Moreover, we analyze the behavior of workflows using a certain type of Boolean matrices. In particular, we establish a necessary and sufficient condition for the logical termination of workflows. Finally, we show that a derived workflow has the same behavior as the original workflow.
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Tuesday, May 24. 2011
R. Cavoretto2, A. De Rossi3 Department of Mathematics, University of Turin, via C. Alberto 10, I–10123, Turin, Italy B. Quatember4 Innsbruck Medical University (Radiology), Anichstrasse 35, 6020 Innsbruck, Austria Received 19 January, 2009; accepted in revised form 18 December, 2010 Abstract: In this paper we propose the use of a local image transformation involving radial basis functions for landmark-based registration of medical images. More precisely, we consider radial basis functions as nodal functions in the modied Shepard method. In this way we obtain an image transformation more accurate and stable than the one given by the global radial basis functions, as shown by numerical results. ⃝c 2011 European Society of Computational Methods in Sciences and Engineering
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Tuesday, May 24. 2011
M.H. Alizadeh2 Department of Mathematics, Islamic Azad University-Nur Branch, Nur, P. O. Box: 46415/444, Iran Received 30 September, 2008; accepted in revised form 8 December, 2010 Abstract: This paper gives a complete characterization of covariance set of regular elements in a C-algebra. Moreover, it is proved that if a and b are simply polar and regular with same range ideals, then they have the same covariance sets. ⃝c 2011 European Society of Computational Methods in Sciences and Engineering Keywords: Generalized inverse, Moore-Penrose inverse, Covariance set, C-algebra. Mathematics Subject Classication: 46L05, 15A09
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