Download or read book DIFFUSION DANS LES ALLIAGES PAR MECANISME LACUNAIRE ET CINETIQUE DE DECOMPOSITION written by MANUEL.. ATHENES and published by . This book was released on 1997 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: NOUS ETUDIONS LA DIFFUSION PAR MECANISME LACUNAIRE ET LES CINETIQUES DE DECOMPOSITION DANS DES ALLIAGES EN UTILISANT UN MODELE ATOMIQUE SUR RESEAU RIGIDE DANS LEQUEL LES INTERACTIONS ENTRE ATOMES SONT REPRESENTEES PAR DES ENERGIES DE PAIRES. POUR UN ALLIAGE BINAIRE, UNE FOIS LE DIAGRAMME DE PHASE FIXE, IL RESTE UN DEGRE DE LIBERTE QUI CORRESPOND A L'ASYMETRIE DES INTERACTIONS ATOMIQUES ENTRE LES DEUX CORPS PURS. LA SIMPLICITE DU MODELE NOUS A PERMIS D'EXPLORER DE MANIERE GENERIQUE L'INFLUENCE DE CETTE ASYMETRIE EN EFFECTUANT DES SIMULATIONS PAR LA METHODE DE MONTE CARLO. NOUS MONTRONS QUE LA VARIATION DE CE PARAMETRE ENGENDRE UNE RICHESSE INSOUPCONNEE DE COMPORTEMENTS DE DIFFUSION ET DE CINETIQUE. L'ALGORITHME CLASSIQUE DIT A TEMPS DE RESIDENCE A ETE AMELIORE POUR PALLIER LE PROBLEME DU PIEGEAGE DE LA LACUNE DANS UNE STRUCTURE ORDONNEE, CE QUI NOUS A PERMIS D'ETUDIER LA DIFFUSION DANS LES PHASES B2 ET L12. NOUS MONTRONS QUE L'ASYMETRIE TRADUIT L'ENERGIE DE LIAISON QUI EXISTE ENTRE UNE LACUNE ET LES ANTISITES, ET QUE CELLE-CI DETERMINE NON SEULEMENT LE DETAIL DES CHEMINS LACUNAIRES, MAIS AUSSI LES ENERGIES D'ACTIVATION DE LA DIFFUSION DE CHACUN DES DEUX ELEMENTS ET LE RAPPORT DE LEURS COEFFICIENTS DE DIFFUSION. NOUS ETUDIONS EGALEMENT LES DIFFERENTS CHEMINS DE DECOMPOSITION LORS DES TOUS PREMIERS STADES DES CINETIQUES DANS DES ALLIAGES PRESENTANT SOIT DES PHASES ORDONNEES, SOIT UNE LACUNE DE MISCIBILITE A L'EQUILIBRE THERMODYNAMIQUE. LORS D'UNE MISE EN ORDRE, NOUS CONSTATONS QUE LA PHASE ORDONNEE APPARAIT DE MANIERE LOCALISEE AUTOUR DES LACUNES POUR UN PARAMETRAGE SYMETRIQUE, OU DE MANIERE HOMOGENE POUR DE FORTES ASYMETRIES. LORS DE LA PRECIPITATION D'UNE PHASE COHERENTE RICHE EN SOLUTE, L'ASYMETRIE EN FIXANT LES INTERACTIONS LACUNE-SOLUTES, GOUVERNE LES MOBILITES DES N-MERES. CELLES-CI DETERMINENT NON SEULEMENT LA CINETIQUE DE PRECIPITATION, ET MAIS AUSSI LA MORPHOLOGIE DE LA PHASE QUI PRECIPITE.

Download or read book CONTRIBUTION A L ETUDE DES MECANISMES DE DIFFUSION DANS LES ALLIAGES METALLIQUES AMORPHES written by Jean-Marc Delaye and published by . This book was released on 1993 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE THESE EST CONSACREE A L'ETUDE DU MECANISME DE DIFFUSION LACUNAIRE DANS LES SYSTEMES AMORPHES LENNARD-JONES MONOELEMENTAIRES ET BINAIRES, PAR UNE METHODE DE SIMULATION PAR DYNAMIQUE MOLECULAIRE. LE PREMIER CHAPITRE CONSTITUE UNE REVUE DE L'ETAT DES CONNAISSANCES AU DEBUT DE LA THESE, LA METHODE UTILISEE EST DECRITE AU CHAPITRE TROIS. NOUS AVONS MONTRE DANS LES CHAPITRES SUIVANTS QUE LES LACUNES, INTRODUITES PAR LE RETRAIT D'UN ATOME, SONT DES DEFAUTS STABLES SUR UN POURCENTAGE ELEVE DE SITES, NOTAMMENT DANS LES SYSTEMES BINAIRES. PAR LE CALCUL DES GRANDEURS THERMODYNAMIQUES, ENTHALPIES ET ENTROPIES DE FORMATION ET DE MIGRATION, NOUS AVONS MONTRE LE RENFORCEMENT DU MECANISME LACUNAIRE DANS UN SYSTEME DESORDONNE PAR RAPPORT A UN CRISTAL DE MEME COMPOSITION, CE QUI PEUT EXPLIQUER LES ORDRES DE GRANDEUR DES COEFFICIENTS DE DIFFUSION MESURES EXPERIMENTALEMENT. PARALLELEMENT, UNE METHODE DE MESURE EXPERIMENTALE DE COEFFICIENTS DE DIFFUSION BASEE SUR L'EVOLUTION DE LA RESISTIVITE D'UN MULTICOUCHES AU COURS DE L'INTERDIFFUSION A ETE MISE AU POINT SUR LE SYSTEME CRISTALLIN OR-ARGENT (CHAPITRE DEUX). DES MESURES SOUS PRESSION PERMETTENT DE DETERMINER LE VOLUME D'ACTIVATION ET NOS RESULTATS SONT EN ACCORD AVEC LES RESULTATS ANTERIEURS

Download or read book Surface Photovoltage Analysis Of Photoactive Materials written by Thomas Dittrich and published by World Scientific. This book was released on 2020-02-04 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface photovoltage (SPV) techniques provide information about photoactive materials with respect to charge separation in space. This book aims to share experience in measuring and analyzing SPV signals and addresses researchers and developers interested in learning more about and in applying SPV methods. For this purpose, basics about processes in photoactive materials and principles of SPV measurements are combined with examples from research and development over the last two decades.SPV measurements with Kelvin probes, fixed capacitors, electron beams and photoelectrons are explained. Details are given for continuous, modulated and transient SPV spectroscopy. Simulation principles of SPV signals by random walks are introduced and applied for small systems. Application examples are selected for the characterization of silicon surfaces, gallium arsenide layers, electronic states in colloidal quantum dots, transport phenomena in metal oxides and local charge separation across photocatalytic active crystallites.

Download or read book Complexity Science and Society written by Jan Bogg and published by Radcliffe Publishing. This book was released on 2007 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complexity is a new interdisciplinary approach to science and society that challenges traditional academic divisions, frameworks and paradigms. This book helps the expert, student or policy practitioner have a better understanding of the enormous potential of complexity, and how it relates to their particular area of interest or expertise.

Download or read book Organization at the Limit written by William Starbuck and published by John Wiley & Sons. This book was released on 2009-02-09 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book offers important insight relevant to Corporate, Governmentand Global organizations management in general. The internationallyrecognised authors tackle vital issues in decision making, howorganizational risk is managed, how can technological andorganizational complexities interact, what are the impediments foreffective learning and how large, medium, and small organizationscan, and in fact must, increase their resilience. Managers,organizational consultants, expert professionals, and trainingspecialists; particularly those in high risk organizations, mayfind the issues covered in the book relevant to their daily workand a potential catalyst for thought and action. A timely analysis of the Columbia disaster and theorganizational lessons that can be learned from it. Includes contributions from those involved in the InvestigationBoard report into the incident. Tackles vital issues such as the role of time pressures andgoal conflict in decision making, and the impediments for effectivelearning. Examines how organizational risk is managed and howtechnological and organizational complexities interact. Assesses how large, medium, and small organizations can, and infact must, increase their resilience. Questions our eagerness to embrace new technologies, yetreluctance to accept the risks of innovation. Offers a step by step understanding of the complex factors thatled to disaster.

Download or read book Proceedings of the Second Resilience Engineering Symposium written by Eric Rigaud and published by Presses des MINES. This book was released on 2006 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: