Martedi' 26 Novembre 2019 presso la sala conferenze dell'IMATI-CNR di Pavia si terranno due seminari nell'ambito del Seminario di Matematica Applicata (IMATI-CNR e Dipartimento di Matematica, Pavia), http://matematica.unipv.it/it/seminari-matematica-applicata

ore 15 precise: "Least Squares Method for Eigenvalue Problem", Fleurianne Bertrand, Humboldt University

ore 16 precise: "Partial relaxation of C^0 vertex continuity of stresses of conforming mixed finite elements for the elasticity problem", Rui Ma, Humboldt University

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Abstract Bertrand. The Least Squares method has been successfully applied to the numerical solution of partial differential equations in several contexts and in connection with various applications. Despite the popularity of the method, its use for the solution of eigenvalue problems arising from partial differential equations has not attracted so much attention so far. In this talk we recall the existing literature on this subject and we discuss various schemes for the approximation of the eigensolutions associated with the Laplace equation. This is joint work with Daniele Boffi.

Abstract Ma. A conforming triangular mixed element recently proposed by Hu and Zhang for linear elasticity is extended by rearranging the global degrees of freedom.
A feature of this extended discrete stress space is its nestedness in the sense that a space on a coarse mesh is a subspace of a space on any refinement, which allows a proof of convergence of a standard adaptive algorithm. The idea is extended to impose a general traction boundary condition on the discrete level. Numerical experiments are provided to illustrate performance on both uniform and adaptive meshes.