Download or read book OPTIMISATION DE LA TREMPE SUPERFICIELLE PAR LASER D ALLIAGES BASE FER written by CHRISTOPHE.. RENARD and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: DANS LE CADRE D'UNE ACTION ENGAGEE AVEC UN INDUSTRIEL FRANCAIS CONCERNANT LE TRAITEMENT DES CONGES DE VILEBREQUIN PAR LASER CO#2, CETTE ETUDE PRESENTE LA METHODOLOGIE ADOPTEE POUR REALISER CE TYPE DE TRAITEMENT SUPERFICIEL EN PHASE SOLIDE SUR DES ALLIAGES BASE FER (ACIERS ET FONTE). POUR CELA, LES PARAMETRES PERTINENTS GOUVERNANT L'INTERACTION LASER-MATERIAU SONT PRECISEMENT DEGAGES ET UN MODELE THERMIQUE AUSSI SIMPLE QU'ANALYTIQUE PERMETTANT LE CHOIX DES CONDITIONS OPERATOIRES EST DEVELOPPE. LE TRAITEMENT DES DIFFERENTES NUANCES EST EFFECTUE AU MOYEN D'UN DISPOSITIF OPTIQUE DE TRANSFORMATION DE FAISCEAU PAR DIVISION ET RECOMBINAISON. LA REPRODUCTIBILITE DE TOUS LES ESSAIS LASERS EST ASSUREE PAR UN SUIVI EN TEMPS REEL DE LA TEMPERATURE DE SURFACE ATTEINTE EN COURS DE TRAITEMENT. ENSUITE, UNE CARACTERISATION METALLURGIQUE ET MECANIQUE DES MATERIAUX TRAITES EST ENGAGEE. CE SAVOIR-FAIRE EST ENSUITE APPLIQUE AU TRAITEMENT D'EPROUVETTES DE SIMULATION DE VILEBREQUIN. UNE DERNIERE PARTIE EST RESERVEE A UNE ANALYSE PRECISE DE L'ENSEMBLE DES RESULTATS DE FATIGUE AU MOYEN DU CRITERE DE CROSSLAND CE QUI PERMET DE MONTRER LA BONNE COHERENCE ENTRE LES RESULTATS OBTENUS SUR DES EPROUVETTES DE GEOMETRIE DIFFERENTE ET PAR LA MEME DE PRECISER L'AMELIORATION DU COMPORTEMENT EN FATIGUE SUSCEPTIBLE D'ETRE ATTEINT SUR UN VILEBREQUIN DONT LES CONGES SERAIENT TRAITES PAR LASER

Download or read book DURCISSEMENT SUPERFICIEL PAR IRRADIATION LASER CO2 ET NEODYME YAG D ALLIAGE A BASE DE FER DE TYPE FONTE APPLICATION A LA TREMPE SUPERFICIELLE DES ALESAGES D UN BLOC CYLINDRE DE MOTEUR DE VEHICULE AUTOMOBILE written by PASCAL.. KIRAT and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: DANS LE CADRE DES TRAITEMENTS DE SURFACE PAR LASERS DE PUISSANCE CO2 ET YAG, NOUS NOUS SOMMES INTERESSES A LA TREMPE SUPERFICIELLE DE LA FONTE A GRAPHITE LAMELLAIRE ET A MATRICE PERLITIQUE QUI CONSTITUE LES BLOCS-MOTEURS DE VEHICULES AUTOMOBILES. CE TRAVAIL PORTE D'ABORD SUR L'AMELIORATION DU COUPLAGE ENTRE LE FAISCEAU LASER ET LA SURFACE METALLIQUE. PLUSIEURS REVETEMENTS ABSORBANTS SONT TESTES. UNE ETUDE EXPERIMENTALE A PERMIS DE DETERMINER LES PARAMETRES (DENSITE DE PUISSANCE, TEMPS D'INTERACTION) CONDUISANT A LA TREMPE MARTENSITIQUE SUR UNE PROFONDEUR DONNEE. LES RESULTATS EXPERIMENTAUX SONT COMPARES AUX PREVISIONS D'UN MODELE THERMIQUE ANALYTIQUE REPOSANT SUR LA RESOLUTION DE L'EQUATION DE CONDUCTION DE LA CHALEUR AU TRAVERS D'UN MILIEU SEMI-INFINI CONSTITUE PAR UN MATERIAU HOMOGENE ET ISOTROPE. DES TRAITEMENTS DE TREMPE SUPERFICIELLE ONT ETE REALISES AVEC UN LASER CO2 CONTINU ET AVEC DES LASERS YAG IMPULSIONNEL ET CONTINU. LES ECHANTILLONS TRAITES SONT CARACTERISES EN TERMES DE MICROSTRUCTURE, DE DIMENSIONS ET DE DURETES DES ZONES DURCIES. LA RUGOSITE DE LA SURFACE INDUITE PAR LA TREMPE EST AUSSI MESUREE. ENFIN, UN MONTAGE OPTIQUE ORIGINAL BASE SUR UN MIROIR A GENERATRICE PARABOLIQUE A ETE DEVELOPPE. IL A SERVI A EFFECTUER LA TREMPE DES ALESAGES DES CYLINDRES DE BLOCS-MOTEURS DE VEHICULES AUTOMOBILES

Download or read book REALISATION ASSISTEE PAR LASER D ALLIAGES DE SURFACE BASE ALUMINIUM OU CUIVRE ASPECTS MECANIQUE PHYSIQUE THERMODYNAMIQUE ET STATISTIQUE written by AHMAD.. ISSA and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: NOUS NOUS SOMMES INTERESSES A LA REALISATION D'ALLIAGES DE SURFACE, PAR IRRADIATION A L'AIDE D'UN LASER CO#2, D'ECHANTILLONS CONSTITUES: SOIT D'UN SUBSTRAT BASE ALUMINIUM, ET D'UN DEPOT DE 30 A 200 MICRONS DE NICKEL OU D'UN DEPOT D'ALLIAGE BASE COBALT; LE BUT EST L'AMELIORATION DES PROPRIETES MECANIQUES ET TRIBOLOGIQUES DE LA SURFACE, SOIT D'UN SUBSTRAT BASE CUIVRE ET D'UN DOUBLE DEPOT DE NICKEL (20-30 MICRONS) ET DE CHROME (1-5 MICRONS); DANS CE CAS LA FINALITE RECHERCHEE EST L'ACCROISSEMENT DES PROPRIETES MECANIQUES ET PHYSICOCHIMIQUES, C'EST-A-DIRE LA RESISTANCE A LA CORROSION. LE PRINCIPE ADOPTE CONSISTE A PORTER LA SURFACE DE L'ECHANTILLON AU-DELA DU POINT DE FUSION, POUR PROVOQUER L'INTERDIFFUSION, EN PHASE LIQUIDE, DES DIFFERENTS ELEMENTS CHIMIQUES EN PRESENCE. APRES UNE PHASE D'OPTIMISATION DES PARAMETRES EXPERIMENTAUX, DES ALLIAGES DE SURFACE SAINS ET HOMOGENES SONT OBTENUS, PUIS CARACTERISES; UNE CORRELATION EST ETABLIE ENTRE LA MICROSTRUCTURE ET LES PROPRIETES MECANIQUES OU PHYSICOCHIMIQUES. EN PARALLELE, NOUS AVONS DEVELOPPE UN MODELE DE TRANSFERT THERMIQUE DANS LES ECHANTILLONS BI-COUCHES. TROIS TYPES DE PARAMETRES ENTRENT EN JEU, LIES AU FAISCEAU LASER LUI-MEME, A L'INTERACTION LASER-MATERIAU ET MATERIAU PROPREMENT DIT (PROPRIETES THERMIQUES ET PHYSICOCHIMIQUES). UNE COMPARAISON AVEC LES RESULTATS EXPERIMENTAUX PERMET DE VALIDER CE MODELE, SEMI-QUANTITATIVEMENT

Download or read book Contribution l tude de l interaction laser mati re written by Didier Kechemair and published by . This book was released on 1989 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pour améliorer la compréhension et les applications industrielles de l'interaction laser-matière, on étudie l'exemple de la trempe superficielle des aciers par laser CO2 continu dont on recherche un modèle numérique validé par des mesures en cours de traitement. On résout l'équation instationnaire de la chaleur, à coefficients dépendant de la température, avec dépôt d'énergie en surface, par éléments finis bidimensionnels. Une configuration expérimentale "étalon" est également définie : le faisceau est homogénéisé par un kaléidoscope, on trempe à cœur les éprouvettes (35NCD16) préalablement pour limiter l'effet de la diffusion du carbone sur l'austénitisation, et on dépose en surface un revêtement absorbant (graphite ou peinture). La comparaison des températures mesurées en profondeur et des duretés permet de valider la technique de mesure. On compare ensuite les cycles thermiques calculés et mesurés, considérant l'absorption comme un paramètre ajustable. Les valeurs obtenues sont assez dispersées, l'identification par calcul du flux absorbé montre les variations du couplage le long de la zone éclairée. On recherche alors la répartition de flux absorbé optimisant le traitement. On discute l'interprétation physique de résultats théoriques obtenus par ailleurs; les premières réalisations expérimentales des répartitions optimales calculées amènent une augmentation du temps de maintien en profondeur avec un risque moindre de fusion en surface. Enfin, on aborde les méthodes de contrôle en temps réel du procédé d'après des techniques d'intelligence artificielle : deux jeux de règles de décision sont suggérés.

Download or read book REALISATION D ALLIAGES DE SURFACE SOUS FAISCEAU LASER written by GUO QIANG.. SONG and published by . This book was released on 1995 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: UN RECENSEMENT DES DIFFERENTES ETUDES REALISEES DANS LE DOMAINE DE L'ALLIAGE DE SURFACE PAR LASER, NOUS A TOUT D'ABORD PERMIS DE FAIRE LE LIEN ENTRE LES DIFFERENTES MICROSTRUCTURES RENCONTREES DANS LES ACIERS CONSTITUANT LES OUTILS DE COUPE ET LEURS PROPRIETES MECANIQUES, ENTRE LE CHOIX DES DIVERS MATERIAUX UTILISES EN MODIFICATION DE SURFACE ET LA NATURE DES LIAISONS CHIMIQUES ENTRE PARTICULES D'APPORT ET MATRICES. A LA SUITE DE CE TRAVAIL, NOUS AVONS REALISE, A L'AIDE D'UN LASER CO#2, DES ALLIAGES DE SURFACE EN INJECTANT TROIS TYPES DE POUDRES: DU CARBURE DE TUNGSTENE ENROBE DE NICKEL, DU CARBURE DE BORE, ET UN MELANGE DE CARBURE DE BORE ET DE ZIRCONE, DANS DEUX TYPES DE SUBSTRAT: ACIER RAPIDE M42 ET ACIER 35CD4. CHAQUE COUCHE TRAITEE PAR LASER A ETE CARACTERISEE PAR DES MESURES DE MICRODURETE, DE CONTRAINTES RESIDUELLES, DES OBSERVATIONS METALLOGRAPHIQUES REALISEES AU MICROSCOPE OPTIQUE ET AU MICROSCOPE ELECTRONIQUE AU BALAYAGE, DES ANALYSES DE PHASES PAR DIFFRACTION DE RAYONS X ET PAR SPECTROSCOPIE ELECTRONIQUE AUGER. TROIS SERIES D'ESSAIS ONT ETE EFFECTUEES: A. INJECTION DE CARBURE DE TUNGSTENE ET DE CARBURE DE BORE DANS L'ACIER RAPIDE M42 L'ACIER RAPIDE M42 REFONDU PAR LASER SANS INJECTION DE POUDRE ATTEINT UNE DURETE DE 1000 HV ; UNE INJECTION DE POUDRE DE CARBURE DE TUNGSTENE PERMET, A CONDITION DE MAINTENIR UN DEBIT DE POUDRE INFERIEUR A 3 G/MN, D'OBTENIR APRES REVENU UNE DURETE DE 1200 HV, DUE A LA PRESENCE DE MARTENSITE ET DE CARBURES DE TYPE M#2#3C#6 ET M#1#2C. L'INJECTION DE CARBURE DE BORE DONNE UNE MICROSTRUCTURE PLUS HETEROGENE OU L'ON RENCONTRE DES PHASES DE FER ET FER , DE BORURE DE FER FE#2#3B ET FE#3B, DE CARBURE M#6C ET DU CARBURE DE BORE NON DISSOUS: UN DEBIT DE 0.8 G/MN A PERMIS D'OBTENIR DES VALEURS DE DURETE COMPRISES ENTRE 1300 HV ET 1900 HV DANS LA ZONE FONDUE. B. INJECTION DE CARBURE DE BORE DANS L'ACIER 35CD4 L'ACIER 35CD4 REFONDU PAR LASER A UNE DURETE DE 800 HV DUE A LA MARTENSITE ET NE PRESENTE NI FISSURE NI POROSITE. L'INJECTION DE CARBURE DE BORE AVEC DEBIT DE POUDRE OPTIMISE PERMET L'OBTENTION D'UN CORDON NON POREUX ET SANS FISSURE A CONDITION DE PRECHAUFFER PREALABLEMENT: DANS CE CAS, LA DURETE VARIANT DE 1400 A 1800 HV EST DUE A UNE STRUCTURE TRES FINE ET HOMOGENE OU LE CARBURE DE BORE BIEN DISSOUS PERMET LA DIFFUSION DU BORE ET DU CARBONE AINSI QUE LA FORMATION DE BORURE DE FER FE#2B (1800 HV) ET D'EUTECTIQUES TRES FINS. L'ACIER 35CD4 TRAITE PAR LASER VOIT AINSI SES PROPRIETES DE SURFACE REJOINDRE CELLES DES ACIERS RAPIDES PLUS CHERS ET GENERALEMENT PLUS PERFORMANTS. C. INJECTION D'UN MELANGE B#4C ET ZIRCONE ZRO#2 DANS L'ACIER 35CD4 LE BUT DE CETTE INJECTION EST D'OPTIMISER LES CONDITIONS OPERATOIRES RENCONTREES AVEC LE B#4C SEUL EN UTILISANT DE LA ZIRCONE PERMETTANT DE SUPPRIMER L'ETAPE DE PRECHAUFFAGE INDISPENSABLE A LA DISPARITION DES FISSURES: EN EFFET ZRO#2 INTRODUIT DES CONTRAINTES EN COMPRESSION DANS LA ZONE FONDUE QUI PERMET DE REFERMER LES FISSURES. ZRO#2 SE TROUVE ALORS A L'ETAT DE PHASE TETRAGONALE INSTABLE A L'INTERIEUR DE LA ZONE FONDUE QUI PRESENTE UNE DURETE CONSTANTE DE 1400 HV SUR UNE PROFONDEUR DE 1.8 MM. DES ALLIAGES DE SURFACE REMARQUABLES PAR LEUR DURETE ET LEURS PROPRIETES MECANIQUES ONT AINSI ETE REALISES PAR INJECTION DE CARBURE DE BORE ET OXYDE DE ZIRCONIUM ; LEUR MICROSTRUCTURE, TRES REPRODUCTIBLE DANS LES CONDITIONS EXPERIMENTALES UTILISEES, NE PRESENTE NI FISSURE NI POROSITE. LEUR UTILISATION DEVRAIT PRESENTER UN INTERET ECONOMIQUE CERTAIN DANS LE DOMAINE INDUSTRIEL. MAIS SURTOUT, D'UN POINT DE VUE THEORIQUE, CETTE ETUDE NOUS A PERMIS D'ETABLIR LE ROLE STABILISANT JOUE PAR L'OXYDE DE ZIRCONIUM AU NIVEAU DE LA REPARTITION DES CONTRAINTES OCCASIONNEES PAR L'INTRODUCTION DE PARTICULES DURES DANS UN SUBSTRAT SOUS FAISCEAU LASER ET DE PRECISER AINSI LES DIFFERENTS MECANISMES QUI ENTRENT EN JEU LORS DE LA SOLIDIFICATION DE TELS ALLIAGES

Download or read book Flexoelectricity in Liquid Crystals written by Agnes Buka and published by World Scientific. This book was released on 2013 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.

Download or read book Government Reports Annual Index written by and published by . This book was released on 1986 with total page 866 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1986 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Historical Dictionary of Iran written by John Henry Lorentz and published by Historical Dictionaries of Asia, Oceania, and the Middle East. This book was released on 2007 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an overview of specific events, movements, people, political and social groups, places, trends, and chronology. Allows for considerable exploration of a number of historical and contemporary topics and issues. The modern period, defined as 1800-present, is covered extensively.

Download or read book Metamorphoses written by Emanuele Coccia and published by John Wiley & Sons. This book was released on 2021-06-09 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are all fascinated by the mystery of metamorphosis – of the caterpillar that transforms itself into a butterfly. Their bodies have almost nothing in common. They don’t share the same world: one crawls on the ground and the other flutters its wings in the air. And yet they are one and the same life. Emanuele Coccia argues that metamorphosis – the phenomenon that allows the same life to subsist in disparate bodies – is the relationship that binds all species together and unites the living with the non-living. Bacteria, viruses, fungi, plants, animals: they are all one and the same life. Each species, including the human species, is the metamorphosis of all those that preceded it – the same life, cobbling together a new body and a new form in order to exist differently. And there is no opposition between the living and the non-living: life is always the reincarnation of the non-living, a carnival of the telluric substance of a planet – the Earth – that continually draws new faces and new ways of being out of even the smallest particle of its disparate body. By highlighting what joins humans together with other forms of life, Coccia’s brilliant reflection on metamorphosis encourages us to abandon our view of the human species as static and independent and to recognize instead that we are part of a much larger and interconnected form of life.

Download or read book Nonlinear Optical Materials written by Jerome V. Moloney and published by Springer Science & Business Media. This book was released on 1998-08-13 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical methods play a significant role in the rapidly growing field of nonlinear optical materials. This volume discusses a number of successful or promising contributions. The overall theme of this volume is twofold: (1) the challenges faced in computing and optimizing nonlinear optical material properties; and (2) the exploitation of these properties in important areas of application. These include the design of optical amplifiers and lasers, as well as novel optical switches. Research topics in this volume include how to exploit the magnetooptic effect, how to work with the nonlinear optical response of materials, how to predict laser-induced breakdown in efficient optical devices, and how to handle electron cloud distortion in femtosecond processes.

Download or read book Historical Dictionary of Pakistan written by Shahid Javed Burki and published by . This book was released on 1999 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pakistan is unlike most other countries in the emerging world. It is one of the two nations – the other being the state of Israel – founded on the basis of religion. Although it was created to provide a homeland for the Muslim community of British India, in its original form it was able to accommodate only about half of the people of Islamic faith who lived in the subcontinent. Pakistan’s birth in 1947 resulted in one of the largest movements of people in human history when some 14 million people left their homes, with 8 million Muslims leaving India for what is now Pakistan and 6 million Hindus and Sikhs moving in the opposite direction. This was the first large-scale incidence of ethnic cleansing the world was to witness. --

Download or read book The Open Work written by Umberto Eco and published by Harvard University Press. This book was released on 1989 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is significant for its concept of "openness"--the artist's decision to leave arrangements of some constituents of a work to the public or to chance--and for its anticipation of two themes of literary theory: the element of multiplicity and plurality in art, and the insistence on literary response as an interaction between reader and text.

Download or read book Cambridge Yearbook of European Legal Studies Vol 13 2010 2011 written by Catherine Barnard and published by Bloomsbury Publishing. This book was released on 2011-12-15 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cambridge Yearbook of European Legal Studies provides a forum for the scrutiny of significant issues in EU Law, the law of the European Convention on Human Rights, and Comparative Law with a 'European' dimension, and particularly those issues which have come to the fore during the year preceding publication. The contributions appearing in the collection are commissioned by the Centre for European Legal Studies (CELS) Cambridge, a research centre in the Law Faculty of the University of Cambridge specialising in European legal issues. The papers presented are at the cutting edge of the fields which they address, and reflect the views of recognised experts drawn from the University world, legal practice, and the institutions of both the EU and its Member States. Inclusion of the comparative dimension brings a fresh perspective to the study of European law, and highlights the effects of globalisation of the law more generally, and the resulting cross fertilisation of norms and ideas that has occurred among previously sovereign and separate legal orders. The Cambridge Yearbook of European Legal Studies is an invaluable resource for those wishing to keep pace with legal developments in the fast moving world of European integration. INDIVIDUAL CHAPTERS Please click on the link below to purchase individual chapters from Volume 13 through Ingenta Connect: www.ingentaconnect.com SUBSCRIPTION TO SERIES To place an annual online subscription or a print standing order through Hart Publishing please click on the link below. Please note that any customers who have a standing order for the printed volumes will now be entitled to free online access. www.hartjournals.co.uk/cyels/subs Editorial Advisory Board: Albertina Albors-Llorens, John Bell, Alan Dashwood, Simon Deakin, David Feldman, Richard Fentiman, Angus Johnston, John Spencer Founding Editors: Alan Dashwood and Angela Ward Ius Commune Prize 2012 Alexandre Saydé wrote Chapter 15 in this volume entitled: 'One Law, Two Competitions: An Enquiry into the Contradictions of Free Movement Law' and we are delighted to announce that he has been awarded the Ius Commune Prize 2012.

Download or read book Socialism Perestroika and the Dilemmas of Soviet Economic Reform written by John E Tedstrom and published by Routledge. This book was released on 2021-12-13 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights that Soviet economic planners and politicians must come to recognize the need to make fundamental changes, not simply incremental refinements, in the failing Soviet system. It examines the dynamics of the process of perestroika and the complexity of individual economic issues.

Download or read book The Ladybird Illustrated written by D H Lawrence and published by . This book was released on 2020-11-09 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Ladybird is a long tale or novella by D. H. Lawrence. It was first drafted in 1915 as a short story entitled The Thimble. Lawrence rewrote and extended it under a new title in December 1921 and sent the final version to his English agent on 9 January 1922. It was collected with two other tales, The Captain's Doll and The Fox, and the three novellas were then published in London by Martin Secker in March 1923 under the title The Ladybird and in New York by Thomas Seltzer as The Captain's Doll in April 1923."

Download or read book Notes on the Minor Prophets written by Henry Allan Ironside and published by . This book was released on 1955 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: