2,481 research outputs found
Numerical analysis of a transmission problem with Signorini contact using mixed-FEM and BEM
No full text© EDP Sciences, SMAI 2011This paper is concerned with the dual formulation of the interface problem consisting of a linear partial differential equation with variable coefficients in some bounded Lipschitz domain Ω in
Rn (n ≥ 2) and the Laplace equation with some radiation condition in the unbounded exterior domain Ωc := Rn\￣Ω. The two problems are coupled by transmission and Signorini contact conditions on the interface Γ = ∂Ω. The exterior part of the interface problem is rewritten using a Neumann to Dirichlet mapping (NtD) given in terms of boundary integral operators. The resulting variational formulation becomes a variational inequality with a linear operator. Then we treat the corresponding numerical scheme and discuss an approximation of the NtD mapping with an appropriate discretization of the inverse Poincar´e-Steklov operator. In particular, assuming some abstract approximation properties and a discrete inf-sup condition, we show unique solvability of the discrete scheme and obtain the corresponding a-priori error estimate. Next, we prove that these assumptions are satisfied with Raviart- Thomas elements and piecewise constants in Ω, and continuous piecewise linear functions on Γ. We suggest a solver based on a modified Uzawa algorithm and show convergence. Finally we present some numerical results illustrating our theory
rec. a Autografi dei letterati italiani: Le Origini e il Trecento / a cura di G. Brunetti, M. Fiorilla e M. Petoletti
No full textIt is here presented the latest volume of the 'Autografi dei letterati italiani' series, that concernes the catalouguing and description of the surviving autograph sources related to 26 literati of the XIII and XIV centuries. The attention is focused on Giacomo Lentini, Bonaggiunta Orbicciani, Albertano da Brescia, Iacomo della Lana, Neri di Landoccio Pagliaresi and Zanobi da Strada
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