Search results for "physics.class-ph"
showing 10 items of 334 documents
Towards a rapidly rotating liquid sodium dynamo experiment
2002
The main characteristics of the Earth's dynamo are reviewed. The combined actions of Coriolisand Lorentz forces lead to the so--called ``magnetostrophic'' regime. We derive an estimate of the power needed to sustain the magnetic field in this regime. We show that an experimentwith liquid sodium can be designed to operate in the magnetostrophic regime. Such an experiment would bring most valuable informations on the mechanisms of planetary dynamos. In order toprepare this large--scale experiment and explore the magnetostrophic balance, a smaller scale liquid sodium set--up has been designed and is being built. It consists of a rapidly rotating spherical shell filled with liquid sodium, in wh…
Fabrication et usinage des guides en verre de tellurite pour l'optique non-linéaire intégrée
2021
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Rational solutions to the mKdV equation associated to particular polynomials
2021
International audience; Rational solutions to the modified Korteweg-de Vries (mKdV) equation are given in terms of a quotient of determinants involving certain particular polynomials. This gives a very efficient method to construct solutions. We construct very easily explicit expressions of these rational solutions for the first orders n = 1 until 10.
L’Observatoire de l’environnement nocturne de La Réunion, un dispositif partenarial de recherche-action territorialisée
2022
Présentation du dispositif Observatoire de l'environnement nocturne (CNRS) et Observatoire de l'environnement nocturne de La Réunion (CNRS/Parc national de La Réunion) aux services internes du Parc national de La Réunion.
Study of acoustic properties and impact behavior of porous materials homogeneous type metal foams and inhomogeneous
2015
This work is concerned with the theoretical and experimental study of the acoustical properties of macroscopically homogenous and inhomogeneous porous media as well as their mechanical response to impacts. The model of Johnson - Champoux - Allard appeared adapted for the acoustical modeling. This model, associated with a recently developed approach involving the concept of parallel transfer matrices has lead to a new approach of macroscopically inhomogeneous porous materials based on “mixtures of materials”. Furthermore, a parametric study of the absorption coefficient as a function of porosity and frequency has been proposed. The maximums of absorption as well as the envelop of the absorpt…
Oblique angle co-deposition of nanocolumnar tungsten thin films with two W sources: Effect of pressure and target current
2022
Two series of tungsten thin films are sputtered on silicon and glass substrates by oblique angle co-deposition technique with an original configuration. Two opposite distinct tungsten targets are simultaneously used, both tilted with an oblique angle of 80°. The growth is performed at low (0.33 Pa) and high (1.5 Pa) argon sputtering pressure and the current intensity applied to the targets varies between 50 and 250 mA. The effect of these deposition parameters on the films microstructure and electrical properties is investigated by scanning and transmission electron microscopy, X-ray diffraction and pole figures, and van der Pauw method. Due to self-shadowing effect, all tungsten sputtered …
Multicriteria optimization of 3D printed wing using PLA reinforced with carbon fiber
2021
The purpose of this work is the optimal conception of a wing built using fused deposition modeling (FDM),<br>which is one of the main additive manufacturing (AM) process. PLA reinforced with carbon fiber was selected for the<br>filament as we have defined their mechanical properties in previous work. The optimization approach use hybrid strategy<br>based on surface response method with kriging model and a heuristic method to avoid to be trapped in local<br>minimization/maximization. The objective functions for this optimization are the weight, the drag (functions to minimize)<br>and the lift (function to maximize) with respect to the failure criteria of the composite material used…
Ballistic and thermalized regimes to tune structure and conducting properties of W-Mo thin films
2022
Detection of Indoor Air Pollutants Using Reactive Sputtering/GLAD of Tin Oxide Thin Films
2021
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Recent developments in the acoustical properties of perforated and porous materials containing dead-end pores
2017
It was shown recently in Nevers, France, Sherbrooke, Canada and Salford, UK, that porous materials with semi-opened pores or materials with open pores bearing lateral cavities or resonators at the microscopic scale of the pores can result in peculiar sound absorption properties. Various examples of these materials can be found in engineering and in everyday life including bio-based materials. The cavities and resonators can be assimilated to dead-end pores, which are opened at one end and closed at the other. The dead-end pores are known to geophysicists. We studied them more recently in the field of engineering acoustics where the saturating fluid is air. The closed ends prevent the fluid …