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Espaces variationnels et mécanique

Joseph Klein (1962)

Annales de l'institut Fourier

Ce travail est essentiellement consacré aux systèmes dynamiques Σ non conservatifs, la force généralisée dépendant à la fois des paramètres de position x α et de vitesse y α . V désignant l’espace-temps de configuration, V l’espace fibré des vecteurs tangents, W celui des directions tangentes à V , on caractérise Σ par son lagrangien homogène L et le tenseur-force S antisymétrique dont le produit contracté par le vecteur vitesse donne le vecteur force généralisé.Dans la première partie, on étudie l’algèbre...

Essential Killing fields of parabolic geometries: projective and conformal structures

Andreas Čap, Karin Melnick (2013)

Open Mathematics

We use the general theory developed in our article [Čap A., Melnick K., Essential Killing fields of parabolic geometries, Indiana Univ. Math. J. (in press)], in the setting of parabolic geometries to reprove known results on special infinitesimal automorphisms of projective and conformal geometries.

Estimates of the Kobayashi-Royden metric in almost complex manifolds

Hervé Gaussier, Alexandre Sukhov (2005)

Bulletin de la Société Mathématique de France

We establish a lower estimate for the Kobayashi-Royden infinitesimal pseudometric on an almost complex manifold ( M , J ) admitting a bounded strictly plurisubharmonic function. We apply this result to study the boundary behaviour of the metric on a strictly pseudoconvex domain in M and to give a sufficient condition for the complete hyperbolicity of a domain in ( M , J ) .

Estimation of vibration frequencies of linear elastic membranes

Luca Sabatini (2018)

Applications of Mathematics

The free motion of a thin elastic linear membrane is described, in a simplyfied model, by a second order linear homogeneous hyperbolic system of partial differential equations whose spatial part is the Laplace Beltrami operator acting on a Riemannian 2-dimensional manifold with boundary. We adapt the estimates of the spectrum of the Laplacian obtained in the last years by several authors for compact closed Riemannian manifolds. To make so, we use the standard technique of the doubled manifold to...

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