32 research outputs found
La tribune peinte de l'Ă©glise Sainte-Eulalie de Millas: Ă©tude technique et conservation
La rĂ©alisation de la tribune de l'Ă©glise de Millas est bien documentĂ©e entre 1440 et 1442. Sa grande originalitĂ© rĂ©side dans la prĂ©sence de 52 tĂȘtes sculptĂ©es et polychromes et de 13 armoiries diffĂ©rentes rĂ©pĂ©tĂ©es Ă 132 reprises qui correspondent probablement aux personnes ayant participĂ© Ă son financement. Elle est composĂ©e de 26 poutres, 104 corbeaux, 156 closoirs et 104 caissons sculptĂ©s. DiffĂ©rentes interventions par le passĂ© ont contribuĂ© Ă endommager la structure, mais surtout la polychromie. Une intervention de restauration est nĂ©cessaire afin de reprendre les assemblages, consolider le bois, refixer la polychromie et Ă©liminer les restes de repeints
Etude des hĂ©tĂ©rogĂ©nĂ©itĂ©s des champs mĂ©caniques dans un acier bainitique Ă lâaide de la diffraction des neutrons
Nous avons développé une méthodologie qui
associe détermination de texture cristallographique et mesures de déformations
Ă©lastiques par diffraction de neutrons afin dâanalyser les contraintes dans des familles
de grains de mĂȘme orientation cristallographique au sein dâun matĂ©riau polycristallin.
Nous présentons ici son application sur un acier bainitique constitutif des cuves des
centrales nuclĂ©aires. Cette mĂ©thode semble ĂȘtre trĂšs prometteuse pour tester et valider
les modÚles de comportement mécanique
The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description
On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds
Fotografia e ciĂȘncia: a utopia da imagem objetiva e seus usos nas ciĂȘncias e na medicina
Sauvegarde et valorisation dâun patrimoine en dĂ©shĂ©rence
Le projet mĂ©diterranĂ©en sur les dĂ©cors de la semaine sainte est nĂ©, dans les PyrĂ©nĂ©es-Orientales, de la mise au jour dâĂ©lĂ©ments matĂ©riels : la re-dĂ©couverte de 4 grandes toiles du Monument dâEspira-de-Conflent, en 1993, suivie dâautres dĂ©cors peints, et dâobjets liĂ©s Ă la liturgie des Jeudi et Vendredi saints. En une dizaine dâannĂ©es ce sont une vingtaine de Monuments et de nombreux objets associĂ©s Ă ces dĂ©cors qui ont Ă©tĂ© retrouvĂ©s dans prĂšs de 40 églises du dĂ©partement. Patrimoine abandonnĂ©..
Introduction : un outil pour la recherche
Lâobjectif essentiel de la publication de ce corpus des Vierges Ă lâEnfant mĂ©diĂ©vales des PyrĂ©nĂ©es-Orientales est de mettre Ă disposition des historiens dâart, conservateurs, scientifiques, historiens, restaurateurs et anthropologues un outil de travail afin dâapprofondir lâĂ©tude de ces Ćuvres du point de vue stylistique, technique, historique et des pratiques dĂ©votionnelles. Tous les passionnĂ©s dâart et de culture y trouveront aussi un catalogue complet des Vierges romanes et gothiques du dĂ©..
Vierges
Cet ouvrage rassemble les actes du Colloque transfrontalier et international « Vierges mĂ©diĂ©vales de Catalogue : mises en perspective » qui sâest dĂ©roulĂ© Ă lâUniversitĂ© de Perpignan, les 1er et 2 dĂ©cembre 2011, en parallĂšle avec lâexposition des Vierges romanes et gothiques des PyrĂ©nĂ©es-Orientales proposĂ©e par le Centre de conservation et de restauration du Patrimoine. Lâinventaire de ces Vierges, dirigĂ© par Jean-Bernard Mathon, est publiĂ© en deuxiĂšme partie. Comme lâindique son titre, ce colloque a eu comme objectif dâĂ©largir les points de vue sur ces Vierges des PyrĂ©nĂ©es-Orientales, en les croisant avec dâautres apports, Ă partir de comparaisons avec des Ćuvres conservĂ©es tant en Espagne, quâen Italie, quâen Languedoc voisin, ou en Ăle de France et plus largement encore en Europe. Ces actes constituent donc un apport important Ă la connaissance des Ćuvres catalanes, en permettant dâen souligner la spĂ©cificitĂ© au sein dâun vaste corpus de Vierges Ă lâEnfant sur lesquelles les publications dâensemble en français sont rares ou dĂ©jĂ anciennes. La seconde partie de ce volume prĂ©sente le rĂ©pertoire exhaustif et abondamment illustrĂ© des 150 Vierges Ă l'Enfant mĂ©diĂ©vales des PyrĂ©nĂ©es-Orientales, Ă©tudiĂ©es du point de vue historique, technique, matĂ©riel et dĂ©votionnel. Ce corpus dĂ©partemental est le premier rĂ©alisĂ© en France ; il ouvre ainsi de nouveaux horizons Ă la recherche
Experimental study of the relation between the permeability of kaolinite and its deformation at micro and macro scale
We present an experimental study of relations between hydraulic properties of clayey rocks and their deformation at bulk and micro scale. The experimentation is based on triaxial deformation of kaolinitic core samples, on permeability measurements, and on several methods of analysis of the microstructure. To produce the samples, remoulded kaolinite material is consolidated by axial loading up to 20 MPa in an oedometric cell. Then, in a triaxial cell, an undrained stress path is applied in order to induce shearing damage in the sample. The permeability of the sample is measured by fluid flow across the sample. Before and after these hydro-mechanical tests, the evolution and the homogeneity of the pore space and moreover the texture of the material are analysed by X-ray tomography, environmental scanning electron microscopy and thermic neutron diffraction. Contrary to expectations, the permeability at the sample scale does not vary significantly, although quite large deformation is reached. The final deformation is heterogeneous, with well-developed shear bands. It appears that the development of compacting and dilating zones generates a heterogeneous permeability field, which results in a negligible variation of the bulk permeability at the sample scale
Role of Zinc and Niobium in the Giant Piezoelectric Response of PbZn1/3Nb2/3O3
International audienceRelaxor ferroelectric perovskites are highly polarizable and can exhibit giant coupling between elastic strain and an applied electric field. Here, we report an in situ extended X-ray absorption fine structure (EXAFS) study of a PbZn1/3Nb2/3O3 (PZN) single crystal as a function of the electric field. We show that the strong dipoles in the NbO6 octahedra bonds are aligned along the four directions close to the orientation of the electric field, while a small reversible polar shift occurs for Zn in the direction of the electric field, i.e., positive or negative. This reversible Zn-O polar shift is proposed to play an important role in both the "easy" switching of the ferroelectric polarization and the giant piezoelectric effect in PZN