1,720,970 research outputs found
A Hierarchical Preconditioner For The Mortar Finite Element Method
No full textMortar elements form a family of nonconforming finite element methods that are more flexible than conforming finite elements and are known to be as accurate as their conforming counterparts. A fast iterative method is developed for linear, second order elliptic equations in the plane. Our algorithm is modeled on a hierarchical basis preconditioner previously analyzed and tested, for the conforming case, by Barry Smith and the second author. A complete analysis and results of numerical experiments are given for lower order mortar elements and geometrically conforming decompositions of the region into subregions. Copyright ©1996, Kent State University.47588Achdou, Y., Kuznetsov, Y.A., Substructuring preconditioners for finite element methods on nonmatching grids (1995) East-West J. Numer. Math., 3, pp. 1-28Achdou, Y., Kuznetsov, Y.A., Pironneau, O., Substructuring preconditioners for the Qi mortar element method (1995) Numer. Math., 71, pp. 419-449Achdou, Y., Maday, Y., Widlund, O.B., Methode iterative de sous-structuration pour les elements avec joints (1996) C.R. Acad. Sci. Paris, 322, pp. 185-190Achdou, Y., Maday, Y., Widlund, O.B., Iterative Substructuring preconditioners for the mortar finite element method in two dimensions (1996) Tech. Rep., Courant Institute of Mathematical Sciences, , In preparationBen Belgacem, F., Discretisations 3D Non Conformes pour la Methode de Decomposition de Domaine des Element avec Joints: Analyse Mathematique et Mise en vre pour le Probleme de Poisson (1993) Tech. Rep. HI-72/93017, , PhD thesis, Universite Pierre et Marie Curie, Paris, France, January Electricite de FranceBen Belgacem, F., Maday, Y., Adaption de la methode des elements avec joints au couplage spectral elments finis en dimension 3: Etude de l'erreur pour l'equation de Poisson, tech. rep., Electricite de France, April 1992 Tech. Rep. HI-72/7095.The mortar element method for three dimensional finite elements (1993) Unpublished Paper Based on Yvon Maday's Talk at the Seventh International Conference of Domain Decomposition Methods in Scientific and Engineering Computing, Held at Penn State University, , October 27-30Bernardi, C., Maday, Y., Mesh adaptivity in finite elements by the mortar method (1995) Tech. Rep. R94029, , Laboratoire d'Analyse Numerique, Universite Pierre et Marie Curie -Centre National de la Recherche Scientifique, JanuaryBernardi, C., Maday, Y., Patera, A.T., A new non conforming approach to domain decomposition: The mortar element method (1994) Collège De France Seminar, , H. Brezis and J.-L. Lions, eds., PitmanBjrstad, P.E., Wldlund, O.B., Iterative methods for the solution of elliptic problems on regions partitioned into substructures (1986) SIAM J. Numer. Anal., 23, pp. 1093-1120Bramble, J.H., A second order finite difference analogue of the first biharmonic boundary value problem (1966) Numer. Math., 9, pp. 236-249Casarin, M.A., Diagonal edge preconditioners in p-version and spectral element methods (1995) Tech. Rep., 704. , Department of Computer Science, Courant Institute, September SIAM J. Sci. ComputClarlet, P.G., (1978) The Finite Element Method for Elliptic Problems, , North-Holland, AmsterdamDryja, M., Additive Schwarz methods for elliptic mortar finite element problems (1996) Modeling and Optimization of Distributed Parameter Systems with Applications to Engineering, , K. Malanowski, Z. Nahorski, and M. Peszynska, eds., IFIP, Chapman & Hall, London, To appearDryja, M., Wldlund, O.B., Schwarz methods of Neumann-Neumann type for threedimensional elliptic finite element problems (1995) Comm. Pure Appl. Math., 48, p. 121155Tallec, P.L.E., Neumann-Neumann domain decomposition algorithms for solving 2D elliptic problems with nonmatching grids (1993) East-West J. Numer. Math., 1, pp. 129-146Maday, Y., Wldlund, O.B., Some iterative sub structuring methods for mortar finite elements: The lower order case (1996) Tech. Rep., Courant Institute of Mathematical Sciences, , In preparationSmith, B.F., Domain Decomposition Algorithms for the Partial Differential Equations of Linear Elasticity Tech. Rep., 517. , PhD thesis, Courant Institute of Mathematical Sciences, September 1990. Department of Computer Science, Courant InstituteSmith, B.F., Wldlund, O.B., A domain decomposition algorithm using a hierarchical basis (1990) SIAM J. Sci. Stat. Comput., 11, pp. 1212-1220Wldlund, O.B., Iterative sub structuring methods: Algorithms and theory for elliptic problems in the plane (1988) First International Symposium on Domain Decomposition Methods for Partial Differential Equations, , R. Glowinski, G. H. Golub, G. A. Meurant, and J. Periaux, eds., Philadelphia, PA, SIAMYserentant, H., On the multi-level splitting of finite element spaces (1986) Numer. Math., 49, pp. 379-41
Local defect correction for time-dependent partial differential equations
No full textA Local Defect Correction (LDC) method for solving time-dependent partial differential equations whose solutions have highly localized properties is discussed. We present some properties of the technique. Results of numerical experiments illustrate the accuracy and the efficiency of the method
A Smooth Transition Approach Between the Vlasov–Poisson and the Euler–Poisson System
No full textIn the present work, we extend a novel numerical algorithm which was constructed for the solution of gas dynamics problems cite{degond1, degond3} to the solution of the Vlasov-Poisson equation in combination with the Euler-Poisson system. The new method is designed for computing the solution of plasma problems which require a localized resolution of the kinetic scale. The main idea relies on the introduction of buffer zones which realize a smooth transition between the kinetic and the fluid regions. The buffer zone is drawn around the kinetic regions by introducing a cut-off function.
We numerically validate the presented method and demonstrate its performances
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
New results on FETI methods for elliptic problems with discontinuos coefficients
No full textS.191-20
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
FETI and Neumann-Neumann iterative substructuring methods. Connections and new results
No full textDie FETI und Neumann-Neumann Algorithmen gehören mit zu den bekanntesten und meist getesteten Gebietszerlegungsverfahren für elliptische partielle Differentialgleichungen. Es handelt sich bei diesen Algorithmen um iterative Substrukturierungsmethoden; beide Verfahren haben viele algorithmische Komponenten gemeinsam, aber es gibt auch einige Unterschiede. Die Absicht dieses Artikels ist es, die Theorie für diese beiden Verfahrensklassen weiter zu vereinheitlichen und eine neue Familie von FETI Algorithmen einzuführen. Für eine Klasse elliptischer Probleme mit heterogenen Koefizienten wird gezeigt, daß die Konvergenzraten dieser Verfahren bezüglich der Koefizienten gleichmäßig beschränkt sind. Für eine Variante der Neumann-Neumann Algorithmen wird die Theorie reformuliert, wobei die Zusammenhänge zu den FETI Verfahren besonders hervorgehoben wird.The FETI and Neumann-Neumann families of algorithms are among the best known and most severely tested domain decomposition methods for elliptic partial differential equations. They are iterative substructuring methods and have many algorithmic components in common but there are also differences. The purpose of this paper is to further unify the theory for these two families of methods and to introduce a new family of FETI algorithms. Bounds on the rate of convergence, which are uniform with respect to the coefficients of a family of elliptic problems with heterogeneous coefficients, are established for these new algorithms. The theory for a variant of the Neumann-Neumann algorithm is also redeveloped stressing similarities to that for the FETI methods
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