Download or read book Acc l ration de la convergence de m thodes num riques parall les pour r soudre des syst mes d quations diff rentielles lin aires et transitoires non lin aires written by Laurent Berenguer and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: La résolution des équations différentielles (EDP/EDO/EDA) est au cœur de la simulation de phénomènes physiques. L'accroissement de la taille et de la complexité des modèles nécessite la mise en œuvre de méthodes de résolution robustes et performantes en termes de temps de calcul. L'objectif de cette thèse est de proposer des méthodes pour accélérer la résolution des équations différentielles par des méthodes de décomposition de domaine. On considère d'abord les méthodes de décomposition de domaine de Schwarz pour la résolution de grands systèmes linéaires issus de la discrétisation d'EDP. Afin d'accélérer la convergence de la méthode de Schwarz, on propose une approximation de l'opérateur de propagation d'erreur. Cette approximation respectera la structure de l'opérateur exact, ce qui conduira à une réduction très significative des temps de calcul sur le problème des écoulements dans les milieux poreux hétérogènes. La deuxième contribution concerne la résolution de la suite de systèmes linéaires provenant de l'intégration en temps de problèmes non linéaires. On propose deux approches en utilisant le fait que la matrice jacobienne ne varie que peu d'un système à l'autre. Premièrement, on applique la mise à jour de Broyden au préconditionneur RAS (Restricted Additive Schwarz) au lieu de recalculer les factorisations LU. La deuxième approche consiste à dédier des processeurs a la mise à jour partielle et asynchrone du préconditionneur RAS. Des résultats numériques sur le problème de la cavité entrainée et sur un problème de réactiondiffusion montrent qu'une accélération super linéaire peut être obtenue. La dernière contribution a pour objet la résolution simultanée des problèmes non linéaires de pas de temps consécutifs. On étudie le cas où la méthode de Broyden est utilisée pour résoudre ces problèmes non linéaires. Dans ce cas, la mise à jour de Broyden peut être propagée d'un pas de temps à l'autre. La parallélisation à travers les pas de temps est également appliquée a la recherche d'une solution initiale consistante pour les équations différentielles algébriques.

Download or read book M thodes Hybrides Pour Les Grilles de Calcul Et Les Supercalculateurs written by Haiwu He and published by Omniscriptum. This book was released on 2010-10 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: De nombreux probl mes scientifiques et industriels ont besoin de la r solution de syst mes lin aires non sym triques grande chelle, qui sont d crits par des matrices creuses de tr s grande taille. On utilise fr quemment dans ce cas des m thodes num riques it ratives et on fait appel au parall lisme pour une r solution rapide et efficace. L'algorithme GMRES(m) est une m thode it rative qui donne de bons r sultats dans la plupart des cas. Mais on observe une limitation sa parall lisation en raison des nombreuses communications produites. Nous pr sentons dans cette th se une m thode hybride GMRES(m)/LS-Arnoldi qui acc l re la convergence gr ce la connaissance des valeurs propres calcul es parall lement par la m thode d'Arnoldi pour les cas r els. Une extension aux cas complexes est galement tudi e. L'environnement XtremWeb est un syst me de grille l ger, tol rant aux d faillances et s curis pour l'ex cution d'applications parall les. Nous pr sentons dans cette th se les implantations de la m thode GMRES(m) sur ce syst me de grille XtremWeb ainsi que sur un environnement distribu de calcul LAM-MPI.

Download or read book Analysis and Optimization of Systems written by Alain Bensoussan and published by . This book was released on 1986 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nondifferentiable Optimization written by Philip Wolfe and published by . This book was released on 1975 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimal Shape Design for Elliptic Systems written by O. Pironneau and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of optimal shape design can be arrived at by asking the following question: "What is the best shape for a physical system?" This book is an applications-oriented study of such physical systems; in particular, those which can be described by an elliptic partial differential equation and where the shape is found by the minimum of a single criterion function. There are many problems of this type in high-technology industries. In fact, most numerical simulations of physical systems are solved not to gain better understanding of the phenomena but to obtain better control and design. Problems of this type are described in Chapter 2. Traditionally, optimal shape design has been treated as a branch of the calculus of variations and more specifically of optimal control. This subject interfaces with no less than four fields: optimization, optimal control, partial differential equations (PDEs), and their numerical solutions-this is the most difficult aspect of the subject. Each of these fields is reviewed briefly: PDEs (Chapter 1), optimization (Chapter 4), optimal control (Chapter 5), and numerical methods (Chapters 1 and 4).

Download or read book Radiation Protection Activities written by United States. Environmental Protection Agency. Office of Radiation Programs and published by . This book was released on 1976 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimization of Distributed Parameter Structures written by Edward J. Haug and published by Kluwer Academic Publishers. This book was released on 1981 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimal Shape Design written by B. Kawohl and published by Springer Science & Business Media. This book was released on 2000-11-16 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optimal Shape Design is concerned with the optimization of some performance criterion dependent (besides the constraints of the problem) on the "shape" of some region. The main topics covered are: the optimal design of a geometrical object, for instance a wing, moving in a fluid; the optimal shape of a region (a harbor), given suitable constraints on the size of the entrance to the harbor, subject to incoming waves; the optimal design of some electrical device subject to constraints on the performance. The aim is to show that Optimal Shape Design, besides its interesting industrial applications, possesses nontrivial mathematical aspects. The main theoretical tools developed here are the homogenization method and domain variations in PDE. The style is mathematically rigorous, but specifically oriented towards applications, and it is intended for both pure and applied mathematicians. The reader is required to know classical PDE theory and basic functional analysis.

Download or read book Operational Radiation Protection written by International Atomic Energy Agency and published by . This book was released on 1990 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides practical guidance on the application of the dose limitation system contained in the Basic Safety Standards for Radiation Protection, Safety Series No. 9, to operational situations both in large nuclear installations and in much smaller facilities, with special reference to the principles of optimisation.

Download or read book Handbook of Functional Equations written by Themistocles M. Rassias and published by Springer. This book was released on 2014-11-18 with total page 555 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Richard Bellman has so elegantly stated at the Second International Conference on General Inequalities (Oberwolfach, 1978), “There are three reasons for the study of inequalities: practical, theoretical, and aesthetic.” On the aesthetic aspects, he said, “As has been pointed out, beauty is in the eye of the beholder. However, it is generally agreed that certain pieces of music, art, or mathematics are beautiful. There is an elegance to inequalities that makes them very attractive.” The content of the Handbook focuses mainly on both old and recent developments on approximate homomorphisms, on a relation between the Hardy–Hilbert and the Gabriel inequality, generalized Hardy–Hilbert type inequalities on multiple weighted Orlicz spaces, half-discrete Hilbert-type inequalities, on affine mappings, on contractive operators, on multiplicative Ostrowski and trapezoid inequalities, Ostrowski type inequalities for the Riemann–Stieltjes integral, means and related functional inequalities, Weighted Gini means, controlled additive relations, Szasz–Mirakyan operators, extremal problems in polynomials and entire functions, applications of functional equations to Dirichlet problem for doubly connected domains, nonlinear elliptic problems depending on parameters, on strongly convex functions, as well as applications to some new algorithms for solving general equilibrium problems, inequalities for the Fisher’s information measures, financial networks, mathematical models of mechanical fields in media with inclusions and holes.