Download or read book Transformation des alumines de transition en alumine alpha Influence d l ments trangers sur la stabilit des alumines written by Pierre Burtin and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les oxydes et hydroxydes d'aluminium sont des produits chimiques très répandus industriellement. La principale utilisation des alumines est la production de l'aluminium, mais elles sont également très employées dans l'industrie des abrasifs, des céramiques et des matériaux réfractaires. De même parmi les oxydes métalliques utilisés dans les processus catalytiques, l'alumine est l'un des plus employés. Elle peut être utilisée comme catalyseur intrinsèque, ou comme l'un des éléments d'un catalyseur multicomposant ou encore comme support d'un catalyseur métallique. En tant que support de catalyseur, une des applications de l'alumine est l'épuration des gaz d'échappement des véhicules automobiles rendue obligatoire depuis quelques années dans certains pays (1974 pour les U.S.A. et le Japon), et qui le deviendra également dans certains pays de la Communauté Européenne au cours des prochaines années (vers 1989 en Allemagne). Les normes ainsi imposées pour la composition des effluents gazeux rejetés par les moteurs et leur teneur en composés nocifs: nécessitent de la part du catalyseur une bonne efficacité. D'autre part le support du catalyseur est caractérisé par la nature du produit, sa résistance mécanique, sa texture et sa stabilité. Toutes ces propriétés doivent être conservées dans les conditions d'utilisation. L'épuration des gaz d'échappement demande donc un système catalytique très performant, notamment pour les propriétés mécaniques et surtout pour la résistance à l'attrition. Et ces propriétés ne doivent pas être affectées aux hautes températures (1000 à 1100°C). A ces températures le support doit également rester neutre vis-à-vis des espèces catalytiques (métal ou oxyde) déposées à sa surface.
Download or read book Effect of Trace Elements V and Ni on Fe Intermetallic Phases Formation and Distribution in DC Cast 5xxx Series Al Ingots written by Gaofeng Li and published by . This book was released on 2012 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolution thermique des alumines de transition Mod lisation written by Marc Dauzat and published by . This book was released on 1989 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Le traitement thermique à 1378K d'une alumine gamma de haute surface spécifique met en évidence plusieurs phénomènes qui modifient considérablement les caractéristiques structurales et texturales du matériau: une importante chute et surface spécifique connue sous le nom de frittage initial des poudres qui se produit lors de la transformation de l'alumine gamma en alumine delta. Expérimentalement, ce phénomène est fortement influence par la présence de vapeur d'eau, ou, dans certains cas par la pression partielle d'oxygène gazeux; une réorganisation du sous-réseau cationique assimilée a un saut des cations aluminium des sites divalents de la structure spinelle vers les sites trivalents des alumines de transition. Cette transformation permet d'obtenir la phase thêta; une précipitation de la seule forme stable à haute température, la phase alpha ou corindon. Cette transformation survient après des hydroxylation complète du matériau. Ces trois phénomènes sont fortement influences par l'addition de cations étrangers: en fonction de la concentration et des caractéristiques de ces cations ces différents phénomènes peuvent être soit ralentis soit accélérés.
Download or read book Etude de la d composition thermique de l alun d ammonium written by Francis Mauss (auteur en génie des procédés).) and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: La décomposition thermique de l'alun d'ammonium permet d'obtenir des alumines alpha de haute pureté. Cette décomposition se déroule en plusieurs étapes: - déshydratation de l'alun d'ammonium hydrate en alun anhydre ; - décomposition de cet alun anhydre en sulfate d'aluminium ; - transformation du sulfate d'aluminium en alumine de transition ; - précipitation de la phase alpha de l'alumine. La décomposition de l'alun dépend fortement de l'environnement gazeux. En particulier la déshydratation de l'alun est influencée par la pression physique dont le rôle est de modifier la diffusion de la vapeur d'eau au sein de l'échantillon. Au cours de la déshydratation, il se forme, selon la pression de vapeur d'eau créée a l'interface réactionnel, deux types d'alun partiellement déshydrate amorphe qui se différencient par leur texture et leur composition. Les conditions de déshydratation jouent un rôle important sur certaines propriétés physico-chimiques des alumines résultantes en modifiant probablement leur concentration en défauts ponctuels ce qui entraine des conséquences au niveau de leur surface spécifique, leur température de transformation gamma-alpha et leur thermoluminescence. Aspect théorique: décomposition des solides, thermodynamique des réactions chimiques diffusion de gaz à travers un solide, texture et structure des solides. Aspect pratique: obtention d'alumine de très haute pureté présentant des propriétés thermoluminescentes intéressantes
Download or read book Etude de la d composition thermique de l alun d ammonium written by Francis Mauss and published by . This book was released on 1994 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: La décomposition thermique de l'alun d'ammonium permet d'obtenir des alumines alpha de haute pureté. Cette décomposition se déroule en plusieurs étapes: - déshydratation de l'alun d'ammonium hydrate en alun anhydre ; - décomposition de cet alun anhydre en sulfate d'aluminium ; - transformation du sulfate d'aluminium en alumine de transition ; - précipitation de la phase alpha de l'alumine. La décomposition de l'alun dépend fortement de l'environnement gazeux. En particulier la déshydratation de l'alun est influencée par la pression physique dont le rôle est de modifier la diffusion de la vapeur d'eau au sein de l'échantillon. Au cours de la déshydratation, il se forme, selon la pression de vapeur d'eau créée a l'interface réactionnel, deux types d'alun partiellement déshydrate amorphe qui se différencient par leur texture et leur composition. Les conditions de déshydratation jouent un rôle important sur certaines propriétés physico-chimiques des alumines résultantes en modifiant probablement leur concentration en défauts ponctuels ce qui entraine des conséquences au niveau de leur surface spécifique, leur température de transformation gamma-alpha et leur thermoluminescence. Aspect théorique: décomposition des solides, thermodynamique des réactions chimiques diffusion de gaz à travers un solide, texture et structure des solides. Aspect pratique: obtention d'alumine de très haute pureté présentant des propriétés thermoluminescentes intéressantes.
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer. This book was released on 1976 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis· seminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) *at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac· tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 20 (thesis year 1975) a total of 10,374 theses titles from 28 Canadian and 239 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. The organization of Volume 20 is identical to that of past years. It consists of theses titles arranged by discipline and by university within each discipline.
Download or read book Antifascisms written by David Ward and published by Fairleigh Dickinson Univ Press. This book was released on 1996 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an in-depth analysis of three of the most crucial years in twentieth-century Italian history, the years 1943-46. After more than two decades of a Fascist regime and a disastrous war experience during which Italy changed sides, these years saw the laying of the political and cultural foundations for what has since become known as Italy's First Republic. Drawing on texts from the literature, film, journalism, and political debate of the period, Antifascisms offers a thorough survey of the personalities and positions that informed the decisions taken in this crucial phase of modern Italian history.
Download or read book Microdosimetry written by Lennart Lindborg and published by CRC Press. This book was released on 2020-10-02 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental microdosimetry deals with the measurement of charged particle energy deposition in tissue equivalent volumes, ranging in size from nanometres to micrometres. Microdosimetry is employed to improve our understanding of the relationship between radiation energy deposition, the resulting biological effects, and the appropriate quantities to be used in characterizing and quantifying radiation quality. Although many reviews and contributions to the field have been published over the past fifty years, this new book is the first to provide a single, up to date, and easily accessible account of experimental microdosimetry. This book is designed to be used in medical, radiation, and health physics courses and by Master's and PhD students. In addition to serving as an introductory text to the field for graduate students, this book will also be of interest as a teaching and reference resource for graduate supervisors and established researchers. Drs. Lennart Lindborg and Anthony Waker have spent a life-time career in experimental microdosimetry research in academic, industrial and regulatory environments and have observed the development of the field from its early days as a recognized discipline; they bring to this book particular knowledge and experience in the design, construction, operation and use of tissue equivalent gas ionization counters and chambers.
Download or read book The U S Sheep Industry written by Richard P. Stillman and published by . This book was released on 1990 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Type Typo written by and published by Omair Nazir. This book was released on with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High LET Radiations in Clinical Radiotherapy written by and published by . This book was released on 1979 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sisters Super Creeps and Slushy Gushy Love Songs written by Karen McCombie and published by . This book was released on 2011 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ally knows her super-efficient big sis Linn finds their chaotic family a bit ... exasperating. But when Linn falls for Q, the tearaway lead singer in a local band, all her sensible ways go out of the window. Everyone else can see that Q's a creep, but does Ally have the courage to burst Linn's heart-shaped bubble?
Download or read book Merriam Webster s Rhyming Dictionary written by and published by . This book was released on 2007 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This new edition of Merriam-Webster's Rhyming Dictionary contains over 71,000 rhyming words, about 16,000 more than the first edition. The additions naturally include words that have come into common use since the earlier book's publication -- words such as busk, blog, out-there, dreadlocked, fearmonger, and jaw-dropper. But most of the book's additions are not actually new to the language. For the first time, most of the two-, three-, four-, and five-word entries found in Merriam-Webster's Collegiate Dictionary have been given their own place in this volume's lists of rhyming words."--Preface.
Download or read book Ptolemy s Almagest written by Ptolemy and published by Princeton University Press. This book was released on 1998-11-08 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ptolemy's Almagest is one of the most influential scientific works in history. A masterpiece of technical exposition, it was the basic textbook of astronomy for more than a thousand years, and still is the main source for our knowledge of ancient astronomy. This translation, based on the standard Greek text of Heiberg, makes the work accessible to English readers in an intelligible and reliable form. It contains numerous corrections derived from medieval Arabic translations and extensive footnotes that take account of the great progress in understanding the work made in this century, due to the discovery of Babylonian records and other researches. It is designed to stand by itself as an interpretation of the original, but it will also be useful as an aid to reading the Greek text.
Download or read book Health Protection written by Samuel Ghebrehewet and published by Oxford University Press. This book was released on 2016 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Health Protection: Principles and practice is a practical guide for practitioners working at all levels in public health and health protection, including those with a non-specialist background. It is the first textbook in health protection to address all three domains within the field (communicable disease control; emergency preparedness, resilience and response (EPRR); and environmental public health) in a comprehensive and integrated manner. Written by leading practitioners in the field, the book is rooted in a practice-led, all-hazards approach, which allows for easy real-world application of the topics discussed. The chapters are arranged in six sections, which begin with an in-depth introduction to the principles of health protection and go on to illuminate the three key elements of the field by providing: case studies and scenarios to describe common and important issues in the practice of health protection; health protection tools, which span epidemiology and statistics, infection control, immunisation, disease surveillance, and audit and service improvement; and evidence about new and emerging health protection issues. It includes more than 100 health protection checklists (SIMCARDs), covering infections from anthrax to yellow fever, non-infectious diseases emergencies and environmental hazards. Written from first-hand experience of managing communicable diseases these provide practical, stand-alone quick reference guides for in-practice use. Both the topical content of Health Protection: Principles and practice, and the clearly described health protection principles the book provides, makes it a highly relevant resource for wider public health and health protection professionals in this continually evolving field.
