Search results for "Matériaux [Chimie]"
showing 4 items of 14 documents
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…
Les matériaux pour capteurs chimiques
2002
National audience; A chemical sensor is composed of one part supplying chemical reco gnition coupled to one transducingsystem. At the recognition origin, interaction with the target chemical species is oftwo types, either electronicexchange, or ionic exchange. Two large classes of materials that can supply recognition proceed: metals andsemiconductors giving rise to electronic exchange and ionic conducting materials giving rise to ionic exchan-ge. This paper is structured in tw o large parts, emphasizing on materi als inducing specific interactions:semiconductor materials (metallic oxides and molecular semiconductors) and ionic conductor materials.In each part will be presented nature of ma…
Conception basée sur les origamis pour l'impression 4D de structures déployables
2020
Deployable structures can be deformed between the different configurations through predetermined mechanisms, showing the great potential in many engineering applications. However, their exquisite and intricate mechanisms also bring a great difficulty to the design of its structure. With the growing 4D printing efforts, its self-transforming characteristics under external stimuli provide new possibilities for deploying complex and challenging driving structures. Furthermore, origami-based engineering has provided tremendous technical support for structural conversion, especially from 2D to 3D states, leading to many design studies based on origami-inspired deployable structures. However, the…
Statistique de l'efficacité de blindage de matériaux composites pour la 5G: méthodes avancées d'échantillonnage
2020
International audience; Cette proposition présente une méthodologie pour l'estimation statistique du niveau de protection offert par des matériaux composites constitués par des fibres de carbone sur une large gamme de fréquences contenant la bande 5G. La variabilité géométrique des nanostructures de carbone (essentiellement en termes de formes et de dimensions) impose, dans un premier temps, une caractérisation fréquentielle précise de la distribution statistique des propriétés diélectriques des matériaux. La propagation, dans un second temps, des incertitudes précédentes au niveau de l'efficacité de blindage des matériaux apporte des contraintes particulières quand aux méthodes statistique…