Numerical multi-scale simulations of the mechanical behavior of β-metastable titanium alloysTi5553 andTi 17

International audienceThe purpose of this study is to investigate the deformation mechanisms in the β-metastable titanium alloys Ti17 and Ti5553, which exhibit an important fraction of β phase (not, vert, similar 40%). A mean field model is introduced to depict the effect of microstructure onmechanical properties. The average behavior of each phase is taken into account : the micromechanical model simulates for each phase the respective elastic anisotropy and thevisco-plastic flow with kinematic and isotropic hardening. A good agreement has been obtained between numerical simulations andexperiments for several microstructure

Mono-boratabenzene and phospholyl zirconocene(IV) derivatives : towards mixed heterocycles zirconocene complexes

In hopes of extending the existing knowledge on the chemistry of phospholyl and boratabenzene complexes of zirconium, which have shown potential notably as polymerization catalysts, this study aims at exploring the synthesis of mono boratabenzene and mono phospholyl zirconium complexes and at studying their reactivity towards the formation of mixed (boratabenzene)(phospholyl)zirconium complexes. Several derivatives of (η5-phospholyl)Zr(NMe2)xCl3−x and (η6-boratabenzene-NMe2)Zr(NMe2)xCl3−x were synthesized and used as precursors for the formation of mixed (boratabenzene)(phospholyl)zirconium complexes

Hybrid spectral-particle method for the turbulent transport of a passive scalar

International audienceThis paper describes a novel hybrid method, combining a spectral and a particle method, to simulate the turbulent transport of a passive scalar. The method is studied from the point of view of accuracy and numerical cost. It leads to a significative speed up over more conventional grid-based methods and allows to address challenging Schmidt numbers. In particular, theoretical predictions of universal scaling in forced homogeneous turbulence are recovered for a wide range of Schmidt numbers for large, intermediate and small scales of the scalar

A batch scheduler with high level components

In this article we present the design choices and the evaluation of a batch scheduler for large clusters, named OAR. This batch scheduler is based upon an original design that emphasizes on low software complexity by using high level tools. The global architecture is built upon the scripting language Perl and the relational database engine Mysql. The goal of the project OAR is to prove that it is possible today to build a complex system for ressource management using such tools without sacrificing efficiency and scalability. Currently, our system offers most of the important features implemented by other batch schedulers such as priority scheduling (by queues), reservations, backfilling and some global computing support. Despite the use of high level tools, our experiments show that our system has performances close to other systems. Furthermore, OAR is currently exploited for the management of 700 nodes (a metropolitan GRID) and has shown good efficiency and robustness

Corte et Omessa – Création d’une voie nouvelle

Le réaménagement de la section de la RN193 entre Corte et Omessa a provoqué une campagne de diagnostic sur son tracé. La construction de 8 km de route nouvelle a permis, au-delà de son périmètre, l’étude d’une des vallées périphériques de Corte. Suite à la prospection de l’ensemble du fuseau, sept parcelles furent sondées. Une seule avait livré quelques tessons modernes, les autres ne présentant comme seul intérêt que d’être sur des replats propices à une mise en culture avec des apports de p..

Structure et dynamique de la dynorphine et de son recepteur

International audienceDynorphin is a neuropeptide involved in pain, addiction and mood regulation. It exerts its activity by binding to the kappa opioid receptor (KOP) which belongs to the large family of G-protein coupled receptors. The dynorphin peptide was discovered in 1975, while its receptor was cloned in 1993. This review will describe: a) the activities and physiological functions of dynorphin and its receptor, b) early structure-activity relationship studies performed before cloning of the receptor (mostly pharmacological and biophysical studies of peptide analogues), c) structure-activity relationship studies performed after cloning of the receptor via receptor mutagenesis and the development of recombinant receptor expression systems, d) structural biology of the opiate receptors culminating in X-ray structures of the four opioid receptors in their inactive state and structures of MOP and KOP receptors in their active state. X-ray and EM structures are combined with NMR data, which gives complementary insight into receptor and peptide dynamics. Molecular modelling greatly benefited from the availability of atomic resolution 3D structures of receptor-ligand complexes and an example of the strategy used to model a dynorphin-KOP receptor complex using NMR data will be described. These achievements have led to a better understanding of the complex dynamics of KOP receptor activation and to the development of new ligands and drugs

Contact élastique entre des surfaces rugueuses représentatives

National audienceDans ce travail nous étudions l'évolution de l'aire réelle de contact entre des surfaces nominalement plates mais réellement rugueuses. Puis nous explicitons la loi phénoménologique proposé dans [28] pour décrire cette évolution. Enfin, nous suggérons des pistes pour le développement de la théorie du contact rugueux en partant des résultats de simulations numériques