Alain Gauthier Sellier

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The Gaia mission is designed as a Galaxy explorer, and will measure simultaneously, in a survey mode, the five or six phase space parameters of all stars brighter than 20th magnitude, as well as providing a description of their astrophysical characteristics. These measurements are obtained by combining an astrometric instrument with micro-arcsecond(More)
Since many decades efforts have been made to reduce the brittleness of cementitious materials by the use of micro and macro fibers of different mechanical, geometrical and physical properties. This contribution presents the results of an experimental investigation carried out to study the effect of fiber aspect ratio on the flexural properties of metallic(More)
The mobility matrix of a spherical particle moving in a spherical cavity, filled with a viscous incompressible fluid, and with no-slip boundary condition at the wall of the cavity, is evaluated from the Oseen tensor for the cavity by the method used by Lorentz for a particle near a planar wall. For the case that the particle is a rigid sphere with no-slip(More)
Clustering is a relevant problem that takes place in many practical environments. This paper presents some meta-heuristic approaches as an alternative to the traditional clustering techniques, like K-means or C-means. They are based on some metaheuristic optimization algorithms as tabu search, simulated annealing, genetic algorithms and ant colony. The(More)
When earthquakes occur, energy released by the earthquake gets induced into the structure as ground motion and this energy has to be dissipated for safety reasons. To release seismic energy, the structure should damage in such a way that on one hand, collapse of structure should not occur and on the other hand, after the earthquake, damage should be(More)
Flexural behaviour of reinforced fibrous concrete beams was investigated in this research study. Two types of metallic fibers were studied: amorphous metallic fibers (FibraFlex fibers), and carbon steel hooked-end fibers (Dramix fibers). Four types of reinforced concretes were made: one control (without fibers) and three fibrous. Among three reinforced(More)
Using Hipparcos parallaxes and proper motions together with radial velocity complementary data (Coravel for late type stars and new ground-based data for early type stars) for several thousand B-F type stars, the velocity ellipsoid has been determined as a function of age. The variations with age of the ratio of the velocity dispersions, of the vertex(More)
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