Nonlinear forced vibration of damped plates by an asymptotic numerical method

International audienceThis work deals with damped nonlinear forced vibrations of thin elastic rectangular plates subjected to harmonic excitation by an asymptotic numerical method. Using the harmonic balance method and Hamilton’s principle, the governing equation is converted into a static formulation. A mixed formulation is used to transform the problem from cubic nonlinearity to quadratic one sequence. Displacement, stress and frequency are represented by power series with respect to a path parameter. Equating the like powers of this parameter, the nonlinear governing equation is transformed into a sequence of linear problems with the same stiffness matrix. Through a single matrix inversion, a considerable number of terms of the perturbation series can easily be computed with a limited computation time. The starting point, corresponding to a regular solution, is obtained by the Newton–Raphson method. In order to increase the step length, Padé approximants are used. Numerical tests are presented and compared with numerical and analytical results in the literature, for different boundary conditions, excitations and damping coefficients

L’exploitation médiévale du plomb argentifère sur le mont Lozère

Avec près de quatre vingt sites à scories de plomb argentifère (vestiges d’anciens ateliers de réduction du minerai) et plus de 230 charbonnières associées (produisant le combustible nécessaire à la réduction), datés du Moyen Âge central et du bas Moyen Âge, le massif du mont Lozère présente un intérêt scientifique exceptionnel. Après une synthèse taphonomique et une discussion sur la représentativité spatiale du corpus disponible, l’analyse archéologique et géographique conduite à trois niveaux scalaires différents plaide pour une organisation territoriale contrôlée par l’alimentation des bas fourneaux en combustible.With nearly 80 sites with argentiferous lead slag (remains of ancient ore reduction workshops) and more than 230 related charcoal-making sites (producing the fuel needed for smelting), dating back to the central Middles Ages and late Middle Ages, the Mont Lozère massif is of exceptional scientific interest. Following a taphonomical summary and a discussion of the representative spatial character of the corpus available, the archaeological and geographical analysis carried out at the three different scale levels, speaks in favour of a territorial organisation controlled by the fuelling of the furnaces

La formation initiale en géomatique

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Le partenariat Universités et collectivités pour une EADSI au Burkina Faso

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