HAL :: Accueil

L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion d'articles scientifiques de niveau recherche, publiés ou non, et de thèses, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Derniers Dépôts

Chimie

Économie et finance quantitative

Informatique

Mathématiques

Physique

Planète et Univers

Science non linéaire

Sciences cognitives

Sciences de l'environnement

Sciences de l'Homme et Société

Sciences de l'ingénieur

Sciences du Vivant

Statistiques

Weighted Mourre's commutator theory, application to Schrödinger operators with oscillating potential

Sylvain Golenia et al.

We present a variant of Mourre's commutator theory. We apply it to prove the limiting absorption principle for Schrödinger operators with a perturbed Wigner-Von Neumann potential at suitable energies. To our knowledge, this result is new since we allow a long range pertubation of the Wigner-Von Neumann potential. Furthermore, we can show that the usual Mourre theory, based on differential inequalities and on the generator of dilations, cannot apply to our Schrödinger operators.

Besov algebras on Lie groups of polynomial growth and related results

Isabelle Gallagher et al.

In this paper we prove an algebra property under pointwise multiplication for Besov spaces defined on Lie groups of polynomial growth. When the setting is restricted to the case of H-type groups, this algebra property is generalized to paraproduct estimates.

Fine Gaussian fluctuations on the Poisson space II: rescaled kernels, marked processes and geometric U-statistics

Raphael Lachieze-Rey et al.

Continuing the analysis initiated in Lachiéze-Rey and Peccati (2011), we use contraction operators to study the normal approximation of random variables having the form of a U-statistic written on the points in the support of a random Poisson measure. Applications are provided: to boolean models, and coverage of random networks.

Simple asymptotic forms for Sommerfeld and Brillouin precursors

Bruno Macke et al.

This article mainly deals with the propagation of step-modulated light pulses in a dense Lorentz-medium at distances such that the medium is opaque in a broad spectral region including the carrier frequency. The transmitted field is then reduced to the celebrated precursors of Sommerfeld and Brillouin, far apart from each other. We obtain simple analytical expressions of the first (Sommerfeld) precursor whose shape only depends on the order of the initial discontinuity of the incident field and whose amplitude rapidly decreases with this order (rise-time effects). We show that, in a strictly speaking asymptotic limit, the second (Brillouin) precursor is entirely determined by the frequency-dependence of the medium attenuation and has a Gaussian or Gaussian-derivative shape. We point out that this result applies to the precursor directly observed in a Debye medium at decimetric wavelengths. When attenuation and group-delay dispersion both contribute to its formation, we establish a more general expression of the Brillouin precursor, containing the previous one (dominant-attenuation limit) and that obtained by Brillouin (dominant-dispersion limit) as particular cases. We finally study the propagation of square or Gaussian pulses and we determine the pulse parameters optimizing the Brillouin precursor. Obtained by standard Laplace-Fourier procedures, our results are explicit and contrast by their simplicity from those derived by the uniform saddle point methods, from which it is very difficult to retrieve our asymptotic forms.

Damage-cluster distributions and size effect on strength in compressive failure

Lucas Girard et al.

We investigate compressive failure of heterogeneous materials on the basis of a continuous progressive-damage model. The model explicitly accounts for tensile and shear local damage and reproduces the main features of compressive failure of brittle materials like rocks or ice. We show that the size distribution of damage clusters, as well as the evolution of an order parameter--the size of the largest damage cluster-- argue for a critical interpretation of fracture. The compressive failure strength follows a normal distribution with a very small size effect on the mean strength, in good agreement with experiments.

SIMULATION OF PARTICLE SEGREGATION IN A BIDISPERSE SUSPENSION

Raphael Pesche et al.

We have developed a numerical simulation including many body hydrodynamic interactions which allows to reproduce particle's migration in a monodisperse or a bidisperse suspension placed in a two dimensional Couette flow. The concentration profiles obtained by numerical simulation have been compared to the predictions of models based on the ideas of Leighton and Acrivos. For monodisperse suspensions it appears that taking into account the flux due to the curvature of streamlines well improve the agreement of the model with the numerical simulation. In the bidisperse case for a ratio of sizes a1/a2=0.2, we observe a strong segregation with the large particles going towards the lower shear rate gradients. Our model for bidisperse suspensions fairly well predicts this behaviour without the addition of others parameters. The comparison between numerical simulations and the bidisperse model will be worked out for different size ratios and volume fractions. Concerning the phase separation in bidisperse 2D suspension under simple shear rate, we perform now a theoretical interpretation including diffusion coefficients in order to predict the appearance of stripes depending on the radius ratio and concentration of the spheres.

À l'attention du déposant

Le dépôt doit être effectué en accord avec les co-auteurs et dans le respect de la politique des éditeurs
La mise en ligne est assujettie à une modération, la direction de HAL se réservant le droit de refuser les articles ne correspondant pas aux critères de l'archive (voir le guide du déposant)
Tout dépôt est définitif, aucun retrait ne sera effectué après la mise en ligne de l'article
Consulter le ManuHAL
Les fichiers textes au format pdf ou les fichiers images composant votre dépôt sont maintenant envoyés au CINES dans un contexte d'archivage à long terme.

À l'attention des lecteurs

Dans un contexte de diffusion électronique, tout auteur conserve ses droits intellectuels, notamment le fait de devoir être correctement cité et reconnu comme l'auteur d'un document.

Déposer

Documents avec texte intégral

195291

Evolution des dépôts

Contact

- support.ccsd.cnrs.fr
-

Actualités

Projet MedOANet (19/04/2012)

Passage à TeXLive2011 (27/02/2012)

Créer votre liste de publication (14/12/2011)

Un nouveau module permettant de faire une page WEB "formatée à son goût" avec un ensemble de publications sélectionnées grâce à des critères de recherche (un chercheur, un laboratoire, une collection...) a été intégré dans HAL.

Métadonnée "équipe de recherche" (17/11/2011)

La métadonnée "équipe de recherche" disponible précédemment au niveau d'un article est maintenant a ajouter pour chaque auteur si vous le souhaitez.

À voir

TED 2009, le discours de Tim Berners-Lee sur le web de données (sous titré en français)