Download or read book tude num rique de l interaction d un atome de carbone avec la dislocation vis dans le fer written by Quoc Hoang Nguyen and published by . This book was released on 2009 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les aciers de structures sont sujets aux phénomène de vieillissement sous déformation qui se traduit, par exemple, par des modifications de la limite d'élasticité, une augmentation du durcissement et une diminution de la ductilité. Le vieillissement statique est associé aux pics et aux paliers de Lüders, tandis que le vieillissement dynamique est associé à l'effet Portevin - Le Chatelier, responsable de la localisation de la plasticité et des instabilités mécaniques. L'origine de ces comportements macroscopiques provient des interactions fortes à l'échelle atomique entre les atomes de soluté, et en particulier le carbone, et les dislocations. Ce travail de thèse se propose de caractériser l'interaction entre un atome de carbone en site interstitiel octaédnque et une dislocation vis par des simulations numériques à l'échelle atomique, Les propriétés des dislocations dans le fer cubique centré étant étroitement liées à la structure de cœur des dislocations, structure dépendant elle-même fortement du potentiel interatomique utilisé, ce travail a été effectué à l'aide d'un potentiel d'interaction empirique récemment mis au point et qui reproduit correctement la structure non dégénérée du cœur de la dislocation vis, comme le prédisent les calculs ab initio, Dans un premier temps, do:s calculs de statique moléculaire ont permis de déterminer les énergies d'interaction entre la dislocation et le carbone pour diverses positions de ce dernier. Une étude dynamique a ensuite été menée permettant de déterminer de manière qualitative l'influence du carbone sur le mouvement de la dislocation et le développement des mécanismes fondamentaux de la plasticité. Les simulations effectuées dans le cadre de cette thèse s'inscrivent dans la démarche de la modélisation multi-échelles dont l'objectif à long terme est de prédire l'évolution des propriétés des matériaux en se basant sur des mécanismes physiques élémentaires décrits depuis les échelles atomiques

Download or read book Int raction dislocations de matrice joints de grains dans le fer written by Omar Khalfallah and published by . This book was released on 1988 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: ANALYSE THEORIQUE PAR LE CALCUL DE LA FORCE IMAGE ET EXPERIMENTALE PAR MICROSCOPIE ELECTRONIQUE EN TRANSMISSION DE L'INTERACTION D'UNE DISLOCATION AVEC UN JOINT DE GRAINS. CALCUL SUR LA BASE DE L'ELASTICITE ANISOTROPE DE L'ENERGIE DONT DERIVE LA FORCE IMAGE POUR DIFFERENTES SITUATIONS CRISTALLOGRAPHIQUES. LES FAIBLES INTERACTIONS SONT ASSOCIEES AUX CONFIGURATIONS DE HAUTE SYMETRIE. LA FORCE IMAGE PEUT AGIR SUR UNE DISLOCATION JUSQU'A UNE DISTANCE DE L'ORDRE DE 100NM. LES SITUATIONS DE NON INCORPORATION DE LA DISLOCATION DE MATRICE AU JOINT S'EXPLIQUENT PAR L'INTERVENTION DES PARAMETRES CRISTALLOGRAPHIQUES.

Download or read book Etude du vieillissement des aciers ferritiques par simulations atomiques written by Romain Candela and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dans les réacteurs à eau pressurisée, les tuyaux des circuits secondaires sont soumis à de fortes pressions et des températures élevées (70 bars, 600 K). Ils sont constitués d'aciers Fe-Mn-C qui sont donc soumis au vieillissement statique, i.e. la formation d'atmosphères de Cottrell qui décorent les dislocations. Les dislocations sont des défauts linéaires dans une matrice, et le mouvement de ces dislocations est responsable de la plasticité dans les matériaux. Les dislocations agissent de plus comme des puits pour les hétéro-interstitiels : il est donc possible d'observer la formation d'atmosphère de Cottrell, ce qui impacte les propriétés macroscopiques de ces aciers en ayant un effet d'ancrage sur les dislocations. En revanche, les boucles de dislocation d'auto interstitiels sont des défauts bien plus mobiles que les dislocations dans le fer bcc. A cause de la haute énergie de formation d'un atome auto interstitiel, ces boucles sont considérées comme la signature du dommage d'irradiation. Leur très grande mobilité fait qu'elles impactent grandement la microstructure du matériau étudié en interagissant avec beaucoup d'autres défauts. Une méthode de simulation atomique est développée donc afin d'étudier la cinétique de formation des atmosphères de Cottrell: le Mixed-Lattice Kinetic Monte-Carlo (MLKMC). Le MLKMC consiste en une division spatiale de la boîte de simulation pour traiter les zones distordues avec k-ART, un KMC sur réseau souple, et traiter les zones non distordues avec l'approximation du réseau rigide. Le modèle est tout d'abord testé pour retrouver le coefficient de diffusion du carbone dans le fer bcc avec succès. Il est ensuite testé sur des dislocations vis et sur des boucles de dislocations d'auto interstitiels dans le fer bcc. Pour la première fois, la formation d'une atmosphère de Cottrell est observée à l'échelle atomique, avec des temps simulés de l'ordre de l'heure à 300 K. Des mécanismes intéressants sont également observés et expliqués, comme l'impact de la dislocation sur la migration des atomes de carbones.

Download or read book Satellite Situation Report written by Goddard Space Flight Center. Office of Public Affairs and published by . This book was released on 1977 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ZnO Thin Films written by Paolo Mele and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) is an n-type semiconductor with versatile applications such as optical devices in ultraviolet region, piezoelectric transducers, transparent electrode for solar cells and gas sensors. This book "ZnO Thin Films: Properties, Performance and Applications" gives a deep insight in the intriguing science of zinc oxide thin films. It is devoted to cover the most recent advances and reviews the state of the art of ZnO thin films applications involving energy harvesting, microelectronics, magnetic devices, photocatalysis, photovoltaics, optics, thermoelectricity, piezoelectricity, electrochemistry, temperature sensing. It serves as a fundamental information source on the techniques and methodologies involved in zinc oxide thin films growth, characterization, post-deposition plasma treatments and device processing. This book will be invaluable to the experts to consolidate their knowledge and provide insight and inspiration to beginners wishing to learn about zinc oxide thin films.

Download or read book Diffusion in Materials DIMAT 2011 written by I. Bezverkhyy and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Conference on Diffusion in Materials (DIMAT) is the benchmark conference series for diffusion in solids. DIMAT 2011 was organized by the University of Bourgogne in association with CNRS, Dijon (France). The conference showcased new results concerning theoretical tools as well as applied research approaches. Diffusion processes affect all types of materials: nanomaterials, materials for energy, metallurgy, glasses and ceramics, but each requires its own numerical tools.Volume is indexed by Thomson Reuters CPCI-S (WoS). This volume comprises most of the contributions presented at DIMAT 2011: 4 plenary lectures delivered by famous high-level scientists plus 88 contributions in the form of keynote lectures, talks and posters.

Download or read book Simon Denny written by Simon Denny and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Simon Denny's new body of work for Portikus ranks among the most ambitious the artist has developed to date. Over the period of one year, the artist researched and developed an intricate project that has grown to considerable dimensions -- both physically and in terms of its critical content. For two months, the monumental gallery space is turned into an homage to technology, communication, and the relentless need for innovation. Simon Denny has produced an embracing and multi-faceted installation that functions as a documentary of the South Korean technology giant Samsung and its global success story. The exhibition's title, "New Management", refers to the legendary management philosophy that Lee Kun-hee, Chairman of the Samsung Group, infamously introduced in the early nineties."--Publisher's website.

Download or read book Molecular Mechanisms of Hormone Action written by Gesellschaft für Biologische Chemie. Colloquium and published by . This book was released on 1989 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Heidegger Change written by Catherine Malabou and published by SUNY Press. This book was released on 2011-12-01 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elaborates the author’s conception of plasticity by proposing a new way of thinking through Heidegger’s writings on change.

Download or read book Space Debris written by Heiner Klinkrad and published by Springer Science & Business Media. This book was released on 2006-09-01 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: The future evolution of the debris environment will be forecast on the basis of traffic models and possible hazard mitigation practices. The text shows how large trackable objects will have re-entry pinpointed and predictions made on related risk assessment for possible ground impact. Models will also be described for meteoroids which are also a prevailing risk.

Download or read book In the Flow written by Boris Groys and published by Verso Books. This book was released on 2016-02-16 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the early 20th century, art and its institutions came under critique from a new democratic and egalitarian spirit. In an age of secularism and materialism, artworks would be understood as merely things among other things. This meant an attack on the techniques of realism, and the traditional mission of the museum, both designed shield a small class of objects from the entropic fate awaiting everything else-and the development of an approach that Boris Groys calls "direct realism": an art that would not produce objects, but practices that could enter the flow of time to live and die like the rest of us. But for more than a century now, every advance in this direction has been quickly followed by new means of preserving art's distinction. In this major new work, Groys, one of the world's leading art theorists, charts the paradoxes produced by this tension, which continues to structure the production and reception of new art. The internet, the latest medium through which artists have attempted to disavow this special status, inverts the most notorious consequence of early modernist developments. If the techniques of mechanical reproduction gave us objects without aura, digital production generates aura without objects, transforming all its materials into vanishing markers of the transitory present.

Download or read book Wim Delvoye written by Wim Delvoye and published by Rectapublishers. This book was released on 2001 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Borrowing its name from the ancient sewer in Rome, Belgian conceptualist Wim Delvoye's new and improved "Cloaca" is a room-sized shit-making machine whose bowels process two meals a day, serving up a mouthful of complex themes: scatalogy and disgust, high and low culture, man as machine and vice-versa, and the inversion of art semiotics. Many of these same concerns are processed in Delvoye's other work, like the life-sized carved walnut replica of a cement truck, the wood cabinet stocked with 32 circular saw blades painted with scenes in Delft China blue, and a herd of pigs tatooed by Antwerp's finest needle-men. Feces and other anal subjects are parsed in accompanying essays by such luminaries as Milan Kundera, Gerardo Mosquera, Dan Cameron, Georges Bataille and Salvador Dali.

Download or read book Water Treatment Handbook written by and published by . This book was released on 2007 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt: