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Affichage de 531 à 540 sur 596

Article dans une revue

Stability results for the approximation of weakly coupled wave equations

Farah Abdallah, Serge Nicaise, Julie Valein, Ali Wehbe

In this note, we consider the approximation of two coupled wave equations with internal damping. Our goal is to damp the spurious high frequency modes by introducing numerical viscosity terms in the approximation schemes. With these viscosity terms, we show the exponential or polynomial decay of…

Comptes Rendus de l'Académie des Sciences - Series I - Mathematics, 2012, 350 (1-2), pp.29-34. ⟨10.1016/j.crma.2011.12.004⟩. ⟨hal-00755739⟩

Article dans une revue

Analytic Regularity for Linear Elliptic Systems in Polygons and Polyhedra

Martin Costabel, Monique Dauge, Serge Nicaise

We prove weighted anisotropic analytic estimates for solutions of second order elliptic boundary value problems in polyhedra. The weighted analytic classes which we use are the same as those introduced by Guo in 1993 in view of establishing exponential convergence for <i>hp</i> finite…

Mathematical Models and Methods in Applied Sciences, 2012, 22 (8), 63 p. ⟨10.1142/S0218202512500157⟩. ⟨hal-00454133v3⟩

Article dans une revue

Influence of temperature on the hydration products of low pH cements

T. T. H. Bach, C. Cau Dit Coumes, Isabelle Pochard, Cyrille Albert-Mercier, B. Revel, André Nonat

The chemical evolution of two hydrated "low pH" binders prepared from binary (60% Portland cement + 40% silica fume) or ternary (37.5% Portland cement +32.5% silica fume + 30% fly-ash) mixtures was characterized over one year at 20 degrees C. 50 degrees C, and 80 degrees C. The main…

Cement and Concrete Research, 2012, 42 (6), pp.805-817. ⟨10.1016/j.cemconres.2012.03.009⟩. ⟨hal-00760349⟩

Article dans une revue

Infinitely many radial solutions of a mean curvature equation in Lorentz-Minkowski space

Denis Bonheure, Colette De Coster, Ann Derlet

In this paper, we show that the quasilinear equation - div(\frac{\nabla u}{\sqrt{1-|\nabla u|^{2}}}) = |u|^{\alpha-2}u, in R^N has a positive smooth radial solution at least for any α > 2 = 2N/(N − 2), N ≥ 3. Our approach is based on the study of the optimizers for the best constant in the…

Rendiconti dell'Istituto di Matematica dell'Universita di Trieste: an International Journal of Mathematics, 2012, 44 (1), pp.259-284. ⟨hal-03721671⟩

Article dans une revue

Existence of solutions for second-order differential inclusions involving proximal normal cones

Frederic Bernicot, Juliette Venel

In this work, we prove global existence of solutions for second order differential problems in a general framework. More precisely, we consider second order differential inclusions involving proximal normal cone to a set-valued map. This set-valued map is supposed to take admissible values (so in…, Dans cet article on démontre un résultat dʼexistence globale de solutions pour des inclusions différentielles du second ordre. Ou consideré plus précisément des inclusions différentielles du second ordre faisant apparaître le cône proximal normal dʼun ensemble C dépendant du temps. La multifonction…

Journal de Mathématiques Pures et Appliquées, 2012, 98 (3), pp.257-294. ⟨10.1016/j.matpur.2012.05.001⟩. ⟨hal-00491094⟩

Article dans une revue

Micro-Macro Correlation in Ferroelectric Materials: Depolarization Mechanism Owing Mechanical Stress

Abdelowahed Hajjaji, Mohamed Rguiti, Yahia Boughaleb, Zina Sassi, Sophie d'Astorg, Rith Ly, Christian Courtois, Gérard Moreau, Anne Leriche

Piezoelectric ceramics are commonly used in numerous piezoelectric actuators and sensors. Most ferroelectric materials behave as piezoelectric for low driving levels. The increase of electric field, temperature or stress levels leads to a depoling and results in some degradation of dielectric and…

Sensor letters, 2011, 9 (6), pp.2190-2193. ⟨10.1166/sl.2011.1792⟩. ⟨hal-04283044⟩

Article dans une revue

Microstructure and Nanoscale Piezoelectric/Ferroelectric Properties in La 2 Ti 2 O 7 Thin Films Grown on (110)‐Oriented Doped Nb:SrTiO 3 Substrates

Zhenmian Shao, Sébastien Saitzek, Pascal Roussel, Anthony Ferri, Émilie Bruyer, Adlane Sayede, Mohamed Rguiti, Olivier Mentré, Rachel Desfeux

(00l)‐Oriented La 2 Ti 2 O 7 (LTO) thin films with monoclinic perovskite‐layer structure [a = 7.806(2) Å, b = 5.552(3) Å, c = 13.015(5) Å, β = 98.62(2)°] have been grown by a sol–gel route on conducting (110)‐oriented doped Nb:SrTiO 3 (STO) substrates. The narrow rocking curves (0.24° width for 004…

Advanced Engineering Materials, 2011, 13 (10), pp.961-969. ⟨10.1002/adem.201100105⟩. ⟨hal-04282981⟩

Article dans une revue

Influence of hydrothermal synthesis conditions on BNT-based piezoceramics

Jean-François Trelcat, Sophie d'Astorg, Philippe Champagne, Christian Courtois, Mohamed Rguiti, Anne Leriche

The Bi0.5Na0.5TiO3 perovskite (BNT) is a very promising lead-free candidate for piezoelectric applications. Nevertheless a low reproducibility is commonly reported for the solid state synthesized BNT. In this work, the hydrothermal synthesis was investigated to improve the BNT ceramics…

Journal of the European Ceramic Society, 2011, 31 (11), pp.1997-2004. ⟨10.1016/j.jeurceramsoc.2011.04.025⟩. ⟨hal-04283000⟩

Article dans une revue

Characterization of sol–gel synthesised lead-free (1−x)Na0.5Bi0.5TiO3–xBaTiO3-based ceramics

A. Chaouchi, S. Kennour, Sophie d'Astorg, Mohamed Rguiti, Christian Courtois, S. Marinel, M. Aliouat

The crystal structure, microstructure, dielectric and ferroelectric properties of (1 − x)Na0.5Bi0.5TiO3–xBaTiO3 ceramics with x = 0, 0.03, 0.05, 0.07 and 0.1 are investigated. A structural variation according to the system composition was investigated by X-ray diffraction (XRD) analyses. The…

Journal of Alloys and Compounds, 2011, 509 (37), pp.9138-9143. ⟨10.1016/j.jallcom.2011.06.085⟩. ⟨hal-02450370⟩

Article dans une revue

Efficient 3D numerical prediction of the pressure wave generated by high-speed trains entering tunnels

David Uystepruyst, Mame William-Louis, Emmanuel Creusé, Serge Nicaise, François Monnoyer de Galland

The topic of this paper is to present a new methodology for the three-dimensional numerical simulation of the entrance of high-speed trains in a tunnel. The movement of the train is made thanks to a technique of sliding meshes and a conservative treatment of the faces between two domains. All parts…

Computers and Fluids, 2011, 47 (1), pp.165-177. ⟨10.1016/j.compfluid.2011.03.005⟩. ⟨hal-00768640⟩