Simulation of the aeroelastic behavior of a possibly detached flow airfoil by a discrete vortex method

International audienceThe aeroelastic behavior of an airfoil results in a complex coupling between the elastic response of the structure and the dynamics of the flow. It can lead to the failure of a lifting surface which consequences could be catastrophic. Experiments and high-order computations contribute to the understanding of this phenomenon, but fast low-order methods are needed for engineering tasks. In the present work, we implement a loose fluid-structure coupling between a discrete-time vortex method, using a leading edge shedding criterion, and the structure motion equations. For each time step, the aerodynamic coefficients are first calculated before the computation of the motion of the structure. Flutter velocity is obtained with the same precision as unsteady standard method. The advantage of the method proposed is the ability to catch the limit cycle for velocities larger than flutter speed due to dynamic stall of the airfoil

Formes et conditions de sortie de la vulnérabilité en milieux populaires

synthèse des recherche de l'équipe Formes et conditions d'entrée et de sortie de la "vulnérabilité" en milieux populaire

Evolution of product phase assemblages during thermal decomposition of muscovite under strong disequilibrium conditions

http://www.minsocam.org/MSA/AmMin/TOC/Abstracts/2006_Abstracts/FM06_Abstracts/Devineau_p413_06.pdfWe investigated the thermal decomposition of muscovite in natural granite powders heated to 1175°C for durations from 5 min to 68 h, at 1 bar, paying special attention to the early stages of decomposition. This study shows that muscovite is completely transformed after 5 min. Muscovite pseudomorphs consist of glass, mullite, and Al-rich oxides. For short durations (5 and 40 min), the Al-rich phase was identiÞ ed by XRD, electron diffraction, and TEM microanalysis as γ-Al2O3 containing 4.8 wt% FeO (total Fe), probably a few weight percents of MgO, and possibly up to 10 wt% SiO2. Faint superstructure spots and diffuse streaks observed in electron-diffraction patterns suggest vacancy or trace elements ordering in the γ-Al2O3 defect spinel structure. γ-Al2O3 displays an unexpected acicular morphology, elongated along three directions at 120° in the basal (001)musc planes and parallel to lateral faces of the former muscovite. Mullite forms rods elongated in the basal (001)musc planes along a direction at 90° from one set of γ-Al2O3 needles. The γ-Al2O3 structure appears to be a metastable phase that is replaced by corundum for longer durations

Sancta Maria

French Marian hymn by Jean-Baptiste Faure with lyrics by J. Bertrand, dedicated to Marie-Henriette, Queen Consort of the Belgians. This edition is arranged for a solo soprano or tenor voice with piano accompaniment.https://ecommons.udayton.edu/imri_sheetmusic/1057/thumbnail.jp

Extreme congestion of microswimmers at a bottleneck constriction

When attracted by a stimulus (e. g. light), microswimmers can build up very densely at a constriction and thus cause clogging. The micro-alga \textit{Chlamydomonas Reinhardtii} is used here as a model system to study this phenomenon. Its negative phototaxis makes the algae swim away from a light source and go through a microfabricated bottleneck-shaped constriction. Successive clogging events interspersed with bursts of algae are observed. A power law decrease is found to describe well the distribution of time lapses of blockages. Moreover, the evacuation time is found to increase when increasing the swimming velocity. These results might be related to the phenomenology of crowd dynamics and in particular what has been called the Faster is Slower effect in the dedicated literature. It also raises the question of the presence of tangential solid friction between motile cells densely packed that may accompany arches formation. Using the framework of crowd dynamics we analyze the microswimmers behavior and in particular question the role of hydrodynamics

La caméline, une plante modèle pour la recherche translationnelle

National audienceEn biologie végétale, la recherche translationnelle vise à accélérer la valorisation de découvertes scientifiques réalisées à partir de plantes modèles au bénéfice de plantes d’intérêt agronomique. Dans ce domaine, la caméline est un outil particulièrement efficace : génétiquement proche de l’espèce modèle Arabidopsis thaliana, elle permet d’évaluer simplement de nouveaux caractères associés aux plantes oléoprotéagineuses

Transpressional tectonics and Carboniferous magmatism in the Limousin, Massif Central, France: Structural and ⁴⁰Ar/³⁹Ar investigations

New structural, microstructural, and 40Ar/39 Ar data from the NW Massif Central (France) provide additional constraints on the timing and tectonic setting of late Variscan granite magmatism. Previous studies had emphasized the role of late orogenic extension in the emplacement of granite plutons in the Limousin region. In contrast, the new data set is consistent with syntectonic emplacement of magma in a dextral simple shear active from 350 to 300 Ma in a transpressional regime. As an alternative hypothesis to late orogenic extension, we propose that magmas migrated into tensional bridges between active P shears associated with a lithospheric shear zone comparable to a pop-up structure. The Galician region, in the western end of the Ibero-Armorican tectonic arc, exhibits major left-lateral ductile shear zones which can be interpreted as conjugate structures to the Limousin and Armorican shear zones. Copyright 2007 by the American Geophysical Union