Applied multi-pulsed laser in surface treatment and numerical–experimental analysis

International audienceThis paper presents a comparison between simulation and experimental results of the melting process of metallic material by a pulsed laser source Nd–YAG. The simulations of temperature and velocity fields of melted material were done by solving the transient heat transfer and fluid-flow equations. Variations of the thermophysical properties were considered. Furthermore, the model included the effects of the surface-tension gradient on the fluid surface and the buoyancy force. The simulation was useful in improving our understanding of the phenomena occurring in the treated material. Using a laser triangulation sensor, an experimental study was also conducted on the surface profile of the melted zones to seek a relationship between the so-called keyhole effect and the laser triangulation measurements. The keyhole effect induced strong surface deformations and often formed cavities, which were undesirable in the surface treatment process. The laser power, energy density, and treatment duration could be optimized to prevent the keyhole effect. The predicted laser melted zone (LMZ) morphology was in good agreement with the corresponding experimental measurements for various irradiation conditions, as long as the keyhole effect did not occur

Valoriser les dires d'acteurs locaux dans les démarches préventives – Retours d'expérience sur la vulnérabilité aux inondations dans trois agglomérations du bassin de la Loire (Nantes, Orléans et Saint-Etienne

International audienceSince a few years, the recurrence of floods causing important material and human damages in Europe and in other parts of the world, led to the development of operational procedures and research in order to reduce its impact This paper presents a flood risk prevention approach successfully combining geomatic tools, multi-criteria analyses to identify the vulnerability of urban areas in the Loire basin and 3 towns (Nantes, Angers,Saint-Etienne, France). The analyses are carried out with homogenous and national database to progressively improve the knowledge on the most vulnerable areas. Transposable to other territories, such systemic approach differs from classical "Top-Down" tools required by the government (prevention plans for example), supporting the idea that the local and stakeholders knowledge (in a "Bottom-Up" way) have to be linked with scientific methods to conduct a better systemic risk prevention and to enhance further appropriated spatial decision-making solutions.Les travaux présentés ont pour objectif d’analyser la mise en œuvre d’outils destinés à réduire la vulnérabilité des zones inondables du bassin versant de la Loire et de trois agglomérations (Nantes, Orléans et St-Etienne). Pour cela, il a été élaboré une méthodologie visant à caractériser la vulnérabilité des espaces urbains soumis au risque inondation en combinant de la géomatique (SIG) à des analyses multicritères (AMC). Les données mobilisées sont disponibles à l’échelle nationale ceci afin de garantir une qualité spatiale et sémantique identique sur la totalité de la surface du bassin (IGN ou l’INSEE par exemple). Cette démarche a pour particularité d’intégrer le point de vue des acteurs concernés (gestionnaires de crise, sécurité civile…) dans le choix des variables du SIG et de l’AMC. L’analyse aboutit à des résultats scientifiques et opérationnels : l’identification d’espaces vulnérables où l’action doit être privilégiée ainsi que la définition d’un outils intégrant les dires d'expert et reproductible pour d’autres territoires. Il faut souligner que la démarche proposée se démarque de celles mises en place dans les approches préventives imposées par l’Etat : il s’agit bien d’intégrer dans une démarche scientifique les avis, positions et priorités des acteurs locaux pour une évaluation plus intégrée du risque d’inondation

Morphology, ontogenesis and mechanics of cervical vertebrae in four species of penguins (Aves: Spheniscidae).

16 pagesInternational audiencePenguins (Aves: Spheniscidae) are pelagic, flightless seabirds, restricted to the southern hemisphere (Antarctic and sub-Antarctic areas, New Zealand, Australia, and nearby islands, as well as parts of South America and South Africa). They spend much of their life at sea, but return to islands and coasts to breed. Penguins are terrestrial as juveniles and aquatic as adults. To improve hydrodynamics, penguins tuck in their necks while swimming. They thus attain an ‘‘ichthyosaur'' or ‘‘cetacean'' body shape: characterised by telescoped cervicals. This mechanism is also used on land, associated with the posture of these birds. Our study of neck structure and cervical vertebrae morphology (morphological description, biometry and contour analysis) of the King Penguin (Aptenodytes patagonicus), Gentoo Penguin (Pygoscelis papua), Macaroni Penguin (Eudyptes chrysolophus) and Humboldt Penguin (Sphensicus humboldti) shows a highly specialised fitting in adults, which develops during ontogenesis. The growth of penguins proceeds by stages and there are key stages with regard to the design of the neck. Despite a common main structure, some characteristics vary between species. Distribution of cervical vertebrae can be defined by six modules. There are differences in modularity between species and also within species between different ontogenetical phases

: Quantification of the morphological evolution of the Hominid skull and heterochronies

International audienceComparisons of adult skulls of various species of great apes, fossil hominids and modem humans in the sagittal, Francfort and ortho-sagittal planes reveal a series of three separate organisation plans: 'GreatApe', 'Australopithecine'and 'Homo', tbe latter including primitive men (Homo ergaster-erectus-neandertalensis) and modern humans (Homo sapiens). Morphological changes between these plans are quantified for the first time here by vector fields. This study confirms the existence of cranio-facial contraction, which occurs as a series of leaps. The juvenile morphology of the great ape skull is broadly preserved in adult Homo sapiens, suggesting that numerous heterochronies have occurred in mosaic during ontogeny (hypermorphosis, hypomorphosis, post-displacements).Les comparaisons réalisées entre des crânes d'individus adultes de diverses espèces de singes supérieurs, d'hommes fossiles et modernes dans les plans sagittal, Francfort et orthosagittal, révèlent la succession de trois plans d'organisation distincts ; - Singe supérieur », « Australopithèque », et « Homo ». renfermant les hommes archaïques {Homo ergaster - erectus - neandertalensis) et les hommes modernes (Homo sapiens). Les changements morphologiques entre ces plans sont quantifiés pour la première fois par des champs vectoriels. Cette étude confirme l'existence d'une contraction crânio-faciale qui s'effectue par à-coups. Au niveau du crâne, la morphologie juvénile du singe supérieur est globalement conservée chez l'adulte d'Homo sapiens, ce qui implique un jeu complexe d'hétérochronies (hyperrnorphose, hypomorphose, post-déplacements

Social Facilitation of Eating Familiar Food in Tufted Capuchins 189

Social facilitation of eating familiar foods might serve to synchronize eating activities within groups. We aimed to assess whether capuchins (Cebus apella) are prompted to eat when observing other conspecifics eat-ing a familiar food. Subjects were 8 male captive-born tufted capuchins. One pair of capuchins acted as demonstrators for the other 6 observer subjects. In the Experimental condition, the demonstrator pair was given fresh chow in addition to having access to the leftover food and ate continuously. In the Control condition, the demonstrator pair had access to food leftover from the morning feed and ate very little. The initiation of feeding by the demon-strator pair prompted the initiation of feeding behavior in the observers, and the latter ate significantly more of their leftovers in the Experimental than in the Control condition. The tempo of the social facilitation of eating fa-miliar foods in capuchins support isomorphic coordination, a process that occurs when one individual’s activity focuses the attention of another in-dividual to the same activity, thereby increasing behavioral similarity in a group. KEY WORDS: capuchin monkey; social facilitation; feeding behavior

Le traitement de l’immigration, entre logique administrative et logique pénale

Les contributions de ce dossier se proposent d’examiner la tendance à la "pénalisation" du contrôle de l’immigration dans une double perspective : en privilégiant les approches empiriques, et en appréhendant cette évolution comme une tension dynamique née non seulement des dispositions législatives, mais aussi des registres d’interaction mobilisés par les acteurs du contrôle