Download or read book Comportement l oxydation des verres m talliques massifs base de zirconium written by Bin Wang and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les verres métalliques massifs à base de zirconium, développés depuis la fin des années 80, présentent des propriétés mécaniques très intéressantes. Ils peuvent être envisagés pour de multiples applications y compris à des températures élevées et il est donc intéressant d'étudier leur résistance à l'oxydation dans de telles conditions. L'objectif fondamental de cette étude consiste à mieux comprendre le rôle de divers paramètre thermodynamiques et chimiques sur le comportement à l'oxydation des verres métalliques à base de zirconium à des températures intermédiaires sous air sec, à déterminer les contraintes résiduelles au sein de la couche d'oxyde formée, en comparaison avec des alliages amorphe cristallisés après un traitement de recuit. La cinétique d'oxydation de ces verres et la structure cristalline de la couche d'oxyde ZrO2 dépend de la température et de la durée d'oxydation : pour des durées courtes d'oxydation et pour une température légèrement inférieure à Tg, la cinétique d'évolution est parabolique alors que si l'échantillon est oxydé à T > Tg, la loi cinétique peut être décomposée en deux parties. Les mêmes alliages cristallisés après un traitement de recuit, s'oxydent selon une loi parabolique quelque soit la température. Pour des durées d'oxydation longues à une température proche de Tg, les lois cinétiques deviennent plus complexes et la cristallisation du verre métallique pouvant avoir lieu au cours des essais d'oxydation. De même la structure cristalline des couches d'oxyde dépend de la température d'oxydation. Ainsi, pour T Tg, la couche d'oxyde des alliages amorphes est uniquement constituée de la zircone tétragonale alors que pour ces mêmes alliages portés à une température T Tg et pour les alliages cristallisés, on observe de la zircone monoclinique. Les mécanismes d'oxydation dépendent de la température d'oxydation. Pour les températures où les alliages restent vitreux, la formation de l'oxyde est due à la fois à la diffusion des ions d'oxygène vers l'intérieur mais également à la diffusion des ions de zirconium vers l'extérieur de la couche. En revanche, pour les alliages en cours de cristallisation, la diffusion des ions de zirconium est progressivement freinée jusqu'à devenue nulle lorsque la cristallisation est totale, l'oxydation étant alors uniquement contrôlée par la diffusion interne des ions d'oxygène.Les contraintes résiduelles correspondantes au sein de couches d'oxyde sont de compression, aussi bien pour les alliages amorphes que pour les alliages cristallisés, et qu'elles augmentent linéairement avec l'épaisseur de la couche. Les contraintes de croissance lors de l'oxydation et résiduelle après l'oxydation sont fortement influencées par le changement de phase de la zircone.
Download or read book In Vessel Melt Retention and Ex Vessel Corium Cooling IAEA Tecdoc No 1906 written by International Atomic Energy Agency and published by International Atomic Energy Agency. This book was released on 2020-08-06 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication results from a technical meeting on phenomenology and technologies relevant to in-vessel melt retention (IVMR) and ex-vessel corium cooling (EVCC). The purpose of the publication is to capture the state of knowledge, at the time of that meeting, related to phenomenology and technologies as well as the challenges and pending issues relevant to IVMR and EVCC for water cooled reactors by summarizing the information provided by the meeting participants in a form useful to practitioners in Member States.
Download or read book Underground Disposal of Radioactive Wastes written by International Atomic Energy Agency and published by . This book was released on 1981 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Arsenic in Drinking Water written by National Research Council and published by National Academies Press. This book was released on 2001-11-26 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Having safe drinking water is important to all Americans. The Environmental Protection Agency's decision in the summer of 2001 to delay implementing a new, more stringent standard for the maximum allowable level for arsenic in drinking water generated a great deal of criticism and controversy. Ultimately at issue were newer data on arsenic beyond those that had been examined in a 1999 National Research Council report. EPA asked the National Research Council for an evaluation of the new data available. The committee's analyses and conclusions are presented in Arsenic in Drinking Water: 2001 Update. New epidemiological studies are critically evaluated, as are new experimental data that provide information on how and at what level arsenic in drinking water can lead to cancer. The report's findings are consistent with those of the 1999 report that found high risks of cancer at the previous federal standard of 50 parts per billion. In fact, the new report concludes that men and women who consume water containing 3 parts per billion of arsenic daily have about a 1 in 1,000 increased risk of developing bladder or lung cancer during their lifetime.
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 Critical Metals Handbook written by Gus Gunn and published by John Wiley & Sons. This book was released on 2014-01-06 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mankind is using a greater variety of metals in greater quantities than ever before. As a result there is increasing global concern over the long-term availability of secure and adequate supplies of the metals needed by society. Critical metals, which are those of growing economic importance that might be susceptible to future scarcity, are a particular worry. For many of these we have little information on how they are concentrated in the Earth’s crust, how to extract them from their ores, and how to use, recycle and dispose of them effectively and safely. Published with the British Geological Survey, the Critical Metals Handbook brings together a wealth of knowledge on critical metals and provides a foundation for improving the future security and sustainability of critical metal supplies. Written by international experts, it provides a unique source of authoritative information on diverse aspects of the critical metals, including geology, deposits, processing, applications, recycling, environmental issues and markets. It is aimed at a broad non-specialist audience, including professionals and academics working in the exploration and mining sectors, in mining finance and investment, and in mineral processing and manufacturing. It will also be a valuable reference for policy makers concerned with resource management, land-use planning, eco-efficiency, recycling and related fields.
Download or read book The Rare Earth Elements written by David A. Atwood and published by John Wiley & Sons. This book was released on 2013-02-19 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lanthanides are of great importance for the electronic industries, this new book (from the EIBC Book Series) provides a comprehensive coverage of the basic chemistry, particularly inorganic chemistry, of the lanthanoid elements, those having a 4f shell of electrons. A chapter is describing the similarity of the Group 3 elements, Sc, Y, La, the group from which the lanthanoids originate and the group 13 elements, particularly aluminum, having similar properties. Inclusion of the group 3 and 13 elements demonstrates how the lanthanoid elements relate to other, more common, elements in the Periodic Table. Beginning chapters describe the occurrence and mineralogy of the elements, with a focus on structural features observed in compounds described in later chapters. The majority of the chapters is organized by the oxidation state of the elements, Ln(0), Ln(II), Ln(III), and Ln(IV). Within this organization the chapters are further distinguished by type of compound, inorganic (oxides and hydroxides, aqueous speciation, halides, alkoxides, amides and thiolates, and chelates) and organometallic. Concluding chapters deal with diverse and critically important applications of the lanthanoids in electronic and magnetic materials, and medical imaging.
Download or read book Radioactive Waste Management and Regulation written by Mason Willrich and published by . This book was released on 1977 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discusses the nature of post-fission radioactive waste, the operations that spent fuel goes through after it is discharged from a reactor, and the problem of waste management.
Download or read book Total Diet Studies written by Gerald G. Moy and published by Springer. This book was released on 2016-08-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unless a food is grossly contaminated, consumers are unable to detect through sight or smell the presence of low levels of toxic chemicals in their foods. Furthermore, the toxic effects of exposure to low levels of chemicals are often manifested slowly, sometimes for decades, as in the case of cancer or organ failure. As a result, safeguarding food from such hazards requires the constant monitoring of the food supply using sophisticated laboratory analysis. While the food industry bears the primary responsibility for assuring the safety of its products, the overall protection of people’s diets from chemical hazards must be considered one of the most important public health functions of any government. Unfortunately, many countries do not have sufficient capability and capacity to monitor the exposure of their populations to many potentially toxic chemicals that could be present in food and drinking water. Without such monitoring, public health authorities in many countries are not able to identify and respond to problems posed by toxic chemicals, which may harm their population and undermine consumer confidence in the safety of the food supply. From a trade perspective, those countries that cannot demonstrate that the food they produce is free of potentially hazardous chemicals will be greatly disadvantaged or even subject to sanctions in the international marketplace. The goal of a total diet study (TDS) is to provide basic information on the levels and trends of exposure to chemicals in foods as consumed by the population. In other words, foods are processed and prepared as typical for a country before they are analyzed in order to better represent actual dietary intakes. Total diet studies have been used to assess the safe use of agricultural chemicals (e.g., pesticides, antibiotics), food additives (e.g., preservatives, sweetening agents), environmental contaminants (e.g., lead, mercury, arsenic, cadmium, PCBs, dioxins), processing contaminants (e.g., acrylamide, polycyclic aromatic hydrocarbons, chloropropanols), and natural contaminants (e.g., aflatoxin, patulin, other mycotoxins) by determining whether dietary exposure to these chemicals are within acceptable limits. Total diet studies can also be applied to certain nutrients where the goal is to assure intakes are not only below safe upper limits, but also above levels deemed necessary to maintain good health. International and national organizations, such as the World Health Organization, the European Food Safety Agency and the US Food and Drug Administration recognize the TDS approach as one of the most cost-effective means of protecting consumers from chemicals in food, for providing essential information for managing food safety, including food standards, and for setting priorities for further investment and study. Total Diet Studies introduces the TDS concept to a wider audience and presents the various steps in the planning and implementation of a TDS. It illustrates how TDSs are being used to protect public health from chemicals in the food supply in many developed and developing countries. The book also examines some of the applications of TDSs to specific chemicals, including contaminants and nutrients.
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 Reactor Fuel Processing written by and published by . This book was released on 1964 with total page 928 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Heat Pipe Technology written by D. A. Reay and published by Elsevier. This book was released on 2015-11-24 with total page 831 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Heat Pipe Technology covers the proceedings of the Fourth International Heat Pipe Conference, held at the Royal Aeronautical Society in London, United Kingdom on September 7-10, 1981. This conference focuses on the advances in heat pipe and thermosyphon technology. This book is organized into seven parts encompassing 69 chapters. The first part describes the design and features of heat pipes, as well as their terrestrial and spacecraft applications. The subsequent parts deal with the performance, heat transfer and hydrodynamic properties, and entrainment of thermosyphon and heat pipes, with an emphasis on their application to energy conservation. The last parts discuss the heat pipe theory, and the experimental techniques and life tests of heat pipes.
