564 research outputs found
A study of composite material damage induced by laser shock waves
A laser shock wave technique has been used to study the damage tolerance of T800/M21 CFRP (Carbon Fiber Reinforced Polymer) composite material with different lay_ups. Different levels of damage have been created according to various laser irradiation conditions. Several characterization methods such as Optical Microscopy, X-ray Radiography, or Interferometric Confocal Microscopy have been used to quantify these defects. The nature of the defects induced by the shock wave propagation has been studied. The sensitivity of the composite material damage to the shock conditions has been shown and quantified. Moreover, the experimental results gathered with each technique have been compared to each other and it leads to a better understanding of the CFRP behavior under high dynamic loading. These original results have enabled the definition of a specific damage criterion for CFRP under dynamic loading
Long range coherent magnetic bound states in superconductors
The quantum coherent coupling of completely different degrees of freedom is a
challenging path towards creating new functionalities for quantum electronics.
Usually the antagonistic coupling between spins of magnetic impurities and
superconductivity leads to the destruction of the superconducting order. Here
we show that a localized classical spin of an iron atom immersed in a
superconducting condensate can give rise to new kind of long range coherent
magnetic quantum state. In addition to the well-known Shiba bound state present
on top of an impurity we reveal the existence of a star shaped pattern which
extends as far as 12 nm from the impurity location. This large spatial
dispersion turns out to be related, in a non-trivial way, to the
superconducting coherence length. Inside star branches we observed short scale
interference fringes with a particle-hole asymmetry. Our theoretical approach
captures these features and relates them to the electronic band structure and
the Fermi wave length of the superconductor. The discovery of a directional
long range effect implies that distant magnetic atoms could coherently interact
leading to new topological superconducting phases with fascinating properties
Abnormal cortical sensorimotor activity during âTargetâ sound detection in subjects with acute acoustic trauma sequelae: an fMRI study
The most common consequences of acute acoustic trauma (AAT) are hearing loss at frequencies above 3 kHz and tinnitus. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to visualize neuronal activation patterns in military adults with AAT and various tinnitus sequelae during an auditory âoddballâ attention task. AAT subjects displayed overactivities principally during reflex of target sound detection, in sensorimotor areas and in emotion-related areas such as the insula, anterior cingulate and prefrontal cortex, in premotor area, in cross-modal sensory associative areas, and, interestingly, in a region of the Rolandic operculum that has recently been shown to be involved in tympanic movements due to air pressure. We propose further investigations of this brain area and fine middle ear investigations, because our results might suggest a model in which AAT tinnitus may arise as a proprioceptive illusion caused by abnormal excitability of middle-ear muscle spindles possibly link with the acoustic reflex and associated with emotional and sensorimotor disturbances
Ăges et modalitĂ©s de la mise en place de la couverture limoneuse de la basse plaine de la Garonne dâaprĂšs lâexemple du site de FontrĂ©al (Castelnau-dâEstrĂ©tefonds, Haute Garonne)
Les opĂ©rations dâarchĂ©ologie prĂ©ventive menĂ©es sur la basse plaine de la Garonne, Ă sa confluence avec les vallĂ©es de lâHers et du Girou, ont permis de rĂ©aliser une sĂ©rie dâobservations concernant lâorigine de la couverture limoneuse. Ainsi, sa mise en place a pu ĂȘtre prĂ©cisĂ©e par lâappoint de donnĂ©es stratigraphiques et sĂ©dimentologiques, couplĂ©es aux informations palĂ©oenvironnementales et archĂ©ologiques. Cette couverture limoneuse, clairement polygĂ©nique, moule les irrĂ©gularitĂ©s du toit du corps alluvial de la basse plaine. Elle dĂ©bute par des limons dâinondation qui nappent les reliefs sablo-graveleux. Une abondante malacofaune y est prĂ©servĂ©e et a fourni des Ă©lĂ©ments convergents pour situer leur accumulation Ă la fin du PlĂ©niglaciaire supĂ©rieur. Dans les points bas de la topographie, cette formation a ensuite Ă©tĂ© recouverte par des limons argileux hydromorphes qui correspondent au colmatage de bas-fonds palustres. Leur accumulation est pro parte synchrone de lâoccupation nĂ©olithique du site de FontrĂ©al et comprend, Ă sa base, du matĂ©riel archĂ©ologique Ă©pars ainsi que quelques foyers lenticulaires en place. La rĂ©partition des vestiges nĂ©olithiques montre, en outre, que la topographie de ce secteur Ă©tait encore nettement diffĂ©renciĂ©e il y a 4 000 Ă 5 000 ans et que les secteurs en relief ont Ă©tĂ© prĂ©fĂ©rentiellement occupĂ©s. Le reste du colmatage est nettement plus rĂ©cent et lâon retrouve, parfois sur plus de deux mĂštres dâĂ©paisseur, des fragments de briques et de mortier roulĂ©s. Leur prĂ©sence permet de rattacher cette importante sĂ©dimentation Ă lâĂ©poque moderne et dĂ©coule de lâimpact des dĂ©boisements massifs et de la mise en culture du versant molassique qui domine le site. Sur la basse plaine, les activitĂ©s agricoles ont finalement achevĂ© son nivellement complet et lui ont donnĂ© lâaspect uniformĂ©ment plan que lâon observe aujourdâhui.Preventive archaeological researches on the lower plain of the Garonne river, around the confluence with the Hers and Girou valleys, allow us to do new observations about the origin of the loam cover. Its origin has been made clearer by the stratigraphic and sedimentological studies, coupled with palaeoenvironnemental and archaeological data. This loam cover, clearly polygenic, blankets the coarse-grained alluvial body of the lower plain. It begins with loams flood deposits which cover the sandy and gravely units. A rich malacofauna was discovered and supplied convergent elements to place their accumulation at the end of the Upper Pleniglacial. In the low-lying areas of the topography, this cover was then covered by clayey silt which corresponds to the filling of paludal depressions. Their accumulation is partially synchronous with the Neolithic occupation of the FontrĂ©al site and includes, at its base, in situ archaeological remains. The distribution of Neolithic remains shows that the topography of this area was still clearly differentiated 4000 - 5000 years ago and that the highest places were preferentially occupied. The rest of the filling, which can be more than two meters thick, is more recent and yielded abundant fragments of bricks and rolled mortar. Their presence allows us to link this important sedimentary phase with the modern period. This should be the consequence of massive deforestations on the sandy-clay hillside that dominates the site. Agricultural activities finished the complete levelling of the lower plain and gave it the uniformly flat aspect that one can see today
Une nécropole protohistorique à incinération dans le Toulousain : le site de Grand Noble 2 à Blagnac (Haute-Garonne)
Faisant suite aux reconnaissances archĂ©ologiques rĂ©alisĂ©es en 2005 sur la ZAC AndromĂšde Ă Blagnac (Haute-Garonne), la fouille prĂ©ventive du site de Grand noble 2 s'est dĂ©roulĂ©e au cours du printemps 2006 et a permis dâĂ©tudier pour la premiĂšre fois dans la vallĂ©e de la Garonne en Midi toulousain une nĂ©cropole protohistorique Ă incinĂ©ration. Cet ensemble regroupe une dizaine de sĂ©pultures rĂ©parties sur une surface dâenviron 800 mÂČ. Les tombes sont limitĂ©es au dĂ©pĂŽt dâun unique ossuaire placĂ© dans une fosse Ă©troite et circulaire comblĂ©e en partie avec les restes du bĂ»cher funĂ©raire. Lâutilisation dâun vase cinĂ©raire fermĂ© par un couvercle est attestĂ©e dans les dĂ©pĂŽts les mieux conservĂ©s. Lâabsence dâoffrandes animales non brĂ»lĂ©es est Ă relever comme celle de dĂ©pĂŽt dâobjets mĂ©talliques. LâĂ©tude anthropologique rĂ©alisĂ©e sur les ossuaires les plus complets montre la prĂ©sence exclusive de sujets adultes. Le mobilier cĂ©ramique prĂ©sente des affinitĂ©s avec les productions du Fer I ancien. Les caractĂ©ristiques gĂ©nĂ©rales des dĂ©pĂŽts permettent de rapprocher ces sĂ©pultures de celles de la vallĂ©e de lâAveyron (Camp dâAlba Ă RĂ©alville, Le Tap Ă NĂ©grepelisse), de la vallĂ©e du Tarn (Gabor Ă Saint-Sulpice-la-Pointe), et du bas Quercy (Camp-de-lâĂglise Sud Ă Flaujac-Poujols) ainsi que de lâAgenais (La GraviĂšre Ă Fauillet, Lesparre et les RibĂ©rotes Ă Barbaste).After the first archaeological investigations accomplished in 2005 on the AndromĂšde ZAC (Commercial Activities Area) in Blagnac (France, Haute-Garonne), the preventive excavations on the site « Grand Nobleâ2 » were carried out during the spring 2006 and allowed the study, for the first time in the Garonne valley, in the area of Toulouse, of a protohistorical incineration necropolis. This site is comprised of ten burials spread over an area of 800 mÂČ. The burials are restricted to a deposit of a single ossuary standing in a small, narrow, round pit partly filled with the funerary woodshed. The use of a cinerary vase sealed with a lid is acknowledged in the best preserved deposits. The absence of unburnt animal offerings should be mentioned as well as the lack of iron artifacts. The anthropological study made on the best preserved ossuaries shows the exclusive presence of adult subjects. The ceramic artifacts show affinities with Old Iron Age I productions. General characteristics of these burial deposits can be compared with those from the Aveyron valley («âCamp d'Alba » in RĂ©alville, «âLe Tap » in NĂ©grepelisse), Tarn valley («âGabor » in Saint-Sulpice-la-Pointe) and from the Low Quercy (âCamp-de-l'Eglise Sud » in Flaujac-Poujols) also those from around Agen («âLa GraviĂšre » in Fauillet, «âLesparre » and «âLes RibĂ©rotes » in Barbaste)
LAser Shock Adhesion Test (LASAT), an innovation dedicated to industry
NonWOSAvailable online for free at http://www.ila.org.in/kiran/kiran_19_2.pdfInternational audienc
Numerical investigation of three-dimensional asymmetric hovering flapping flight
Direct numerical simulations are performed to assess the aerodynamic performance of three-dimensional wings undergoing asymmetric hovering flapping flight. A large number of flapping kinematics is investigated, varying the pitch rate and the upstroke and downstroke angles of attack. We show that, for all cases, time-average performance is driven, to leading order, by the mean angle of attack over a flapping period despite the increased contribution of drag to vertical force with increased stroke plane angle. We hence suggest that asymmetric hovering is not intrinsically more efficient than normal hovering, conversely to what has been previously reported in the literature. This may explain the underrepresentation of this flight mode in nature
MENTOR ou une méthodologie et des outils opérationnels de conception et de qualification de sites de mesures en réseau d'assainissement
International audienceLe projet MENTOR (MEasurement sites conception method for sewer NeTwORks) a pour objectif principal d'aider les gestionnaires dans la mise en place d'une instrumentation intégrée de la chaßne de mesures visant à mieux surveiller en continu la quantité et la qualité des masses d'eau rejetées par les systÚmes urbains d'assainissement. Ce projet permettra la mise au point d'outils opérationnels destinés aux gestionnaires et aux responsables de métrologie des réseaux d'assainissement urbains. Il fournira également des recommandations au niveau organisationnel qui aideront à l'acquisition de " bonnes pratiques métrologiques ". Nous présenterons le détail de la démarche puis nous illustrerons cela par quelques cas concrets traités par les partenaires du projet
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