Résistance au cisaillement d'une liaison monobloc CFC/cuivre

La résistance au cisaillement de la liaison CFC/cuivre réalisée par procédé AMC est testée dans la configuration monobloc. Un dispositif spécifique a été développé pour permettre de tester la liaison suivant des secteurs de 53° afin d'évaluer la tenue de la liaison en fonction de son orientation par rapport aux directions principales du CFC, matériau orthotrope, et du flux thermique subi par la liaison lors de tests de fatigue. Les résultats obtenus sont comparés aux contraintes résiduelles lors de l’assemblage, calculées par éléments finis

La longue séquence de Marchésieux: reconstitution de paléoenvironnements marins durant le premier cycle glaciaire de l'hémisphère nord

International audienceA l'échelle des cinq derniers millions d'années, les enregistrements paléoclimatiques restitués par les sédiments océaniques illustrent le contrôle des paramètres orbitaux (précession, obliquité et excentricité) sur le climat global. La tendance au refroidissement qui accompagne la fin du Néogène est ainsi marquée, vers -2,4 Ma, par le développement rapide des calottes de glace de l'hémisphère nord (Shackleton et al., 1984). Alors que l'histoire du climat global restituée par les enregistrements océaniques est sans cesse précisée, les données concernant l'évolution des environnements continentaux et côtiers au cours de ces changements restent essentiellement fragmentaires. Le forage effectué à Marchésieux (Manche; Normandie) a permis de réaliser une étude pluridisciplinaire de la signature de ce premier cycle glaciaire de l'hémisphère nord (Prétiglien). Les premiers résultats stratigraphiques, paléoenvironnementaux (eustatisme, température, paléobathymétrie) sont présentés

Low loss coatings for the VIRGO large mirrors

présentée par L. PinardThe goal of the VIRGO program is to build a giant Michelson type interferometer (3 kilometer long arms) to detect gravitational waves. Large optical components (350 mm in diameter), having extremely low loss at 1064 nm, are needed. Today, the Ion beam Sputtering is the only deposition technique able to produce optical components with such performances. Consequently, a large ion beam sputtering deposition system was built to coat large optics up to 700 mm in diameter. The performances of this coater are described in term of layer uniformity on large scale and optical losses (absorption and scattering characterization). The VIRGO interferometer needs six main mirrors. The first set was ready in June 2002 and its installation is in progress on the VIRGO site (Italy). The optical performances of this first set are discussed. The requirements at 1064 nm are all satisfied. Indeed, the absorption level is close to 1 ppm (part per million), the scattering is lower than 5 ppm and the R.M.S. wavefront of these optics is lower than 8 nm on 150 mm in diameter. Finally, some solutions are proposed to further improve these performances, especially the absorption level (lower than 0.1 ppm) and the mechanical quality factor Q of the mirrors (thermal noise reduction)

Sand injectites

A study was conducted to understand the impact of injectites (sandstone dikes and sills), subsurface exploration, and hydrocarbon reservoirs. The study used sediments of the Great Valley sequence disintegrated from the Sierra Nevada mountains. It was observed during the study that a injection event caused the formation of the Panoche injectite complex and some of the dikes reached to the ocean. The study also used dating techniques for marine fossils to determine the exact timing of the injection event. The distribution and orientation of injectities at the Panoche helped to determine the state of stress at time of sand intrusion. FMI Fullbore Formation MicroImager, the OBMI OilBase MicroImager, and the UBI Ultrasonic Borehole Imager are some borehole imaging tools that can be used to detect sand injectities.</p

Importations et remaniements de thanatofaunes dans les sables de la plate-forme profonde des approches occidentales de la Manche

Macro- and micro-faunas are reported from six gravity cores collected at a mean depth of 150 m in the surficial deposits of the Kaiser sand bank in the Southern Western Channel Approaches. These are bivalves (mainly), gastropods, echinids, crustaceans and foraminifers. These fauna present a very rich association of numerous, well preserved species from various ecological settings. Such an association is commonly reported from the continental shelf of the last transgressive cycle. In addition, the sediment comprises two imported faunal associations. The first one corresponds to thanatocaenoses of Pliocene/lowermost Pleistocene and Weichselian age, reworked respectively from the underlying celtic incised valley fills and the Celtic Sand Banks. The absence of Quaternary fauna prior to the Weichselian suggests that the introduction of Pliocene sources occurred during the last climatic cycle. The second stage of importation took place after the last transgression in the Western Channel, and corresponds to the enrichment of the sediment in coastal fauna derived from western Brittany by the the predominant ebb tidal current. The variations of taxonomic diversity from core to core suggest a sediment transport around the bank that matches the one deduced from the study of tidal bedforms. At the present day, the wave action is highlighted by accumulation of species of the same shape, size and density inside storm beds. However, the survival within these beds of very small,juvenile shells indicate that each storm reworking was short in duration

Scattered light noise in gravitational wave interferometric detectors : a statistical approach

Available from INIST (FR), Document Supply Service, under shelf-number : RP 14800 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc