Download or read book ETUDE DE RESONATEURS ET D OSCILLATEURS A QUARTZ A TRES BASSES TEMPERATURES written by ABDELLATIF.. EL HABTI and published by . This book was released on 1993 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: CE MEMOIRE TRAITE, EN SA MAJEURE PARTIE, DE LA MESURE DU COEFFICIENT DE QUALITE DES RESONATEURS A QUARTZ AYANT SUBI DIFFERENTS TRAITEMENTS DE SURFACE. LES MESURES SONT EFFECTUEES ENTRE 300 K ET 1,4 K ET POUR DIFFERENTS PARTIELS. ON MONTRE QU'EN DESSOUS DE 20 K, L'INVERSE DU COEFFICIENT DE QUALITE EST LA SOMME D'UN TERME EN T PUISSANCE 4 ATTRIBUE A L'ATTENUATION INTRINSEQUE DU CRISTAL DE QUARTZ ET D'UN TERME CONSTANT. CE DERNIER TERME QUI VARIE CONSIDERABLEMENT D'UN QUARTZ A UN AUTRE EST ATTRIBUE A LA RUGOSITE EN SURFACE, A LA PRESENCE D'UNE COUCHE AMORPHE EN SURFACE ET EVENTUELLEMENT A L'AMORTISSEMENT PAR LES SUPPORTS. CE RESULTAT EST OBTENU APRES EVALUATION PAR DES MODELES THEORIQUES D'UNE PART ET D'AUTRE PART PAR DES EXAMENS SUR DES RESONATEURS DONT LES QUARTZ ONT ETE ANALYSES AUX RAYONS X ET PAR UNE METHODE D'INTERFEROMETRIE POUR LE CONTROLE DE L'ETAT DE SURFACE. LA SECONDE PARTIE DE CE TRAVAIL EST CONSACREE A LA REALISATION D'UN OSCILLATEUR QUI FONCTIONNE AUSSI BIEN A LA TEMPERATURE AMBIANTE QU'A TRES BASSE TEMPERATURE. CET OSCILLATEUR A PERMIS DE MESURER LA VARIATION DE LA FREQUENCE EN FONCTION DE LA TEMPERATURE POUR DIFFERENTES COUPES DE QUARTZ A SIMPLE ROTATION. ON TROUVE POUR T INFERIEURE A 15 K UNE VARIATION DE FREQUENCE DE L'ORDRE DE 1 HZ PAR #OK

Download or read book tude et r alisation d un oscillateur quartz tr s basse temp rature written by Gabriel Mossuz and published by . This book was released on 1975 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: ETUDE D'OSCILLATEURS A QUARTZ DEVANT FONCTIONNER A TRES BASSE TEMPERATURE. L'ECART DE FREQUENCE D'OSCILLATION ENREGISTRE PEUT ETRE CORRIGE EN REALISANT A LA T AMBIANTE DES QUARTZ DE FREQUENCE CONVENABLE. UTILISATION D'UN MATERIEL CRYOGENIQUE TRES EVOLUE. ETUDE DU VIEILLISSEMENT DES RESONATEURS A QUARTZ ET DES COMPOSANTS ELECTRONIQUES AUX T CRYOGENIQUES. ETUDE DE LA STABILITE A COURT TERME. ETUDE DU RESONATEUR ET DE L'ELECTRONIQUE DE L'OSCILLATEUR, L'UTILISATION DE TRES BASSES TEMPERATURES DOIT PERMETTRE D'AMELIORER LES STABILITES.

Download or read book Evaluation des potentialit s des mat riaux du type langasite pour la r alisation d oscillateurs ultra stables written by Joël Imbaud and published by . This book was released on 2008 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les travaux présentés dans ce mémoire portent sur l'amélioration des sources ultra-stables de fréquences dans le domaine des temps courts (typiquement inférieurs à une minute). Deux voies d'investigations ont été explorées. L'évaluation des potentialités des matériaux de la famille de la langasite (LGS). Une classification des coefficients de qualité (Q) des matériaux LGS et langatate (LGT) en fonction de leurs provenances a été mise en évidence. Les premiers prototypes de résonateurs à ondes de volume ont eté réalisés dans un cristal de LGT à fort Q. A cette occasion un procédé de fabrication spécifique a été mis au point. Une électronique d'oscillateur et un packaging thermique adaptés aux caractéristiques de ces résonateurs ont été développés. Enfin, ces premiers prototypes d'oscillateurs ont été caractérisés en terme de stabilité temporelle et de vieillissement. La mise en place d'un ensemble expérimental permettant la réfrigération d'oscillateurs à résonateurs à ondes de volume à des températures inférieures à celles de l'hélium liquide (4,2K). Pour cela, des résonateurs en quartz de coupe SC et LD, et en LGT de coupe Y, ont été caractérisés à basses températures. Une campagne de mesures systématiques a révélé des coefficients de qualité exceptionnels pour certains modes de vibration. Par ailleurs, différents modèles de transistors ont été testés et l'une des références testées a été modélisée simplement, à température cryogénique. Deux premiers prototypes d'oscillateurs à résonateur à quartz de coupe SC ont été développés puis testés à basses températures. Il en résulte les toutes premières caractérisations en terme de stabilité temporelle.

Download or read book Contribution l tude d un oscillateur quartz de tr s haute fr quence written by pascal Siffert and published by . This book was released on 1974 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: RAPPEL CONCERNANT LA MESURE DES INSTABILITES DE FREQUENCE D'UN OSCILLATEUR DANS LE DOMAINE TEMPOREL ET SPECTRAL, LE BRUIT ENGENDRE DANS LA BOUCLE OSCILLATRICE, LE BRUIT RAMENE PAR LES AMPLIFICATEURS DE SORTIE. ETUDE DU QUARTZ EN TANT QUE RESONATEUR. MISE EN EVIDENCE DES PROBLEMES POSES PAR LA TRES HAUTE FREQUENCE D'OSCILLATION (125 MHZ) ET SON EFFET SUR LE COEFFICIENT DE QUALITE. METHODES DE MESURE DANS LE DOMAINE TEMPOREL ET LE DOMAINE SPECTRAL. RESULTATS DE MESURE

Download or read book R sonateurs ondes acoustiques de volume pi g es tr s basses temp rature written by Jérémy Bon and published by . This book was released on 2018 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Depuis plusieurs années, le département Temps-Fréquence de l'institut FEMTO-ST mène une étude sur le comportement des résonateurs à ondes acoustiques de volume à énergie piégée dans des cristaux à quartz à température cryogénique, typiquement proche de 4 K. Les performances en termes de coefficient de qualité mécanique relevé à ces températures, plusieurs milliards à quelques dizaines de MHz, font des cavités acoustiques en quartz de bons candidats pour des sources de fréquences cryogéniques ultrastables.Les travaux présentés dans ce manuscrit s'inscrivent dans la continuité de ce programme d'étude. Ils visent à consolider l'intérêt du quartz mais aussi à envisager des solutions alternatives à base de matériaux à très faibles pertes acoustiques mais non piézoélectriques pour lesquels l'excitation optique est une alternative crédible. Les présents travaux peuvent être résumés en trois parties majeures :- La première partie a été réalisée dans le but de déterminer une coupe de quartz possédant un point d'inversion sur sa caractéristique fréquence-température aux températures cryogéniques. La seule régulation de température du résonateur d'une source de fréquence ultrastable est en effet insuffisante sans l'existence d'un tel point qui doit servir de point de fonctionnement à la régulation thermique. La recherche d'une coupe compensée a nécessité une campagne préliminaire de mesure des coefficients de température des coefficients élastiques du matériau, inconnus à basses températures. Il a alors été possible, à partir de la connaissance de ces coefficients, d'identifier par le calcul puis de réaliser une coupe remplissant les conditions recherchées.- La seconde partie a pour objectif de faire la preuve de concept consistant à utiliser une cavité acoustique en quartz en cavité optique. Dans sa version de base, le résonateur à quartz à onde de volume piégée est plan-convexe (pour assurer le piégeage) et à électrodes (métalliques pour assurer l'excitation électrique !) déposées sur chacune de ses faces. Il est démontré, théoriquement et expérimentalement, qu'une telle géométrie fonctionne en cavité optique, avec son avantage de simplicité mais avec ses limites. Cette structure de base doit être mise à profit pour le couplage optomécanique abordé en troisième partie et constitue le socle de conception de dispositifs optomécaniques plus performants.- La troisième partie est consacrée à l'évaluation de la pertinence du couplage optomécanique de tels dispositifs fonctionnant à température cryogénique. Une étude portant sur la quantification théorique du couplage optomécanique que peut atteindre une telle cavité a été réalisée.

Download or read book ICREEC 2019 written by Ahmed Belasri and published by Springer Nature. This book was released on 2020-06-10 with total page 659 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights peer reviewed articles from the 1st International Conference on Renewable Energy and Energy Conversion, ICREEC 2019, held at Oran in Algeria. It presents recent advances, brings together researchers and professionals in the area and presents a platform to exchange ideas and establish opportunities for a sustainable future. Topics covered in this proceedings, but not limited to, are photovoltaic systems, bioenergy, laser and plasma technology, fluid and flow for energy, software for energy and impact of energy on the environment.

Download or read book Ceramic Materials written by Philippe Boch and published by John Wiley & Sons. This book was released on 2010-01-05 with total page 593 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is primarily an introduction to the vast family of ceramic materials. The first part is devoted to the basics of ceramics and processes: raw materials, powders synthesis, shaping and sintering. It discusses traditional ceramics as well as “technical” ceramics – both oxide and non-oxide – which have multiple developments. The second part focuses on properties and applications, and discusses both structural and functional ceramics, including bioceramics. The fields of abrasion, cutting and tribology illustrate the importance of mechanical properties. It also deals with the questions/answers of a ceramicist regarding electronuclear technology. As chemistry is an essential discipline for ceramicists, the book shows, in particular, what soft chemistry can contribute as a result of sol-gel methods.

Download or read book Frequency and Time written by P. Kartaschoff and published by . This book was released on 1978 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Organic Solid State Lasers written by Sébastien Forget and published by Springer. This book was released on 2013-07-03 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic lasers are broadly tunable coherent sources, potentially compact, convenient and manufactured at low-costs. Appeared in the mid 60’s as solid-state alternatives for liquid dye lasers, they recently gained a new dimension after the demonstration of organic semiconductor lasers in the 90's. More recently, new perspectives appeared at the nanoscale, with organic polariton and surface plasmon lasers. After a brief reminder to laser physics, a first chapter exposes what makes organic solid-state organic lasers specific. The laser architectures used in organic lasers are then reviewed, with a state-of-the-art review of the performances of devices with regard to output power, threshold, lifetime, beam quality etc. A survey of the recent trends in the field is given, highlighting the latest developments with a special focus on the challenges remaining for achieving direct electrical pumping of organic semiconductor lasers. A last chapter covers the applications of organic solid-state lasers.

Download or read book Molecular Beams written by Norman Ramsey and published by Oxford University Press. This book was released on 1956 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: First published in 1956, this classic work by N.F. Ramsey, 1989 Nobel Laureate in Physics, provides an account of atomic and molecular structure. After an introductory section reviewing experimental apparatus and the kinds of quantities that can be measured, Ramsey provides comprehensive accounts of gas kinetics, chemical equilibria, and atomic and nuclear magnetic moments by nonresonance methods. He also provides tables of nuclear moments, as well as detailed accounts of nuclear and molecular interactions. Finally there are sections on atomic fine and hyperfine structure, and the design of experimental apparatus. The focus throughout is on the physics of beams composed of electrically neutral particles. As a seminal work by one of the world's leading scientists, this volume will interest students and researchers in a range of fields, including atomic physics, physical chemistry, spectroscopy, and biological chemistry.

Download or read book Physical Properties of Amorphous Materials written by David Adler and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public ,and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach.

Download or read book Laser 50 Years Of Discoveries written by Fabien Bretenaker and published by World Scientific. This book was released on 2014-10-27 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book provides an overview of the principle and applications of lasers enriched with numerous illustrations.Being over fifty years old, lasers continue to amaze us. Their performance characteristics are constantly reaching new limits, and the scope of their applications continues to expand. Yet, it took years of effort by teams of physicists to transform the fundamental notions of Einstein into the first experimental beam of laser light. And history is still going on as fundamental research is now triggered by its remarkable properties.This book addresses every aspects of laser light, from its fundamental principles to its industrial applications, at a level particularly suited for high school teachers, students, and anybody curious about science and technology.

Download or read book Fundamentals of Ceramic Powder Processing and Synthesis written by Terry A. Ring and published by Elsevier. This book was released on 1996-04-30 with total page 985 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ceramic powder synthesis and processing are two of the most important technologies in chemical engineering and the ceramics-related area of materials science. This book covers both the processing and the synthesis ofceramic powders in great depth and is indeed the only up-to-date, comprehensive source on the subject available.The application of modern scientific and engineering methods to the field of ceramic powder synthesis has resulted in much greater control of properties. Fundamentals of Ceramic Powder Processing and Synthesis presents examples of these modern methods as they apply to ceramic powders. The book is organized to describe the natural and synthetic raw materials that comprise contemporary ceramics. It covers the three reactant processes used in synthetic ceramic powder synthesis: solid, liquid, andgas.Ceramic powder processing, as a field of materials processing, is undergoing rapid expansion. The present volume is intended as a complete and useful source on this subject of great current interest. It provides comprehensive coverage from a strong chemistry and chemical engineering perspective and is especially applicable to materials scientists, chemical engineers, and applied chemists.Key Features* The most complete and updated reference source on the subject* Comprehensive coverage from a stron chemical engineering and chemistry perspective* Emphasis on both natural and synthetic raw materials in ceramic powder synthesis* Information on reaction kinetics* Superior, more comprehensive coverage than that in existing texts* Sample problems and exercises* Problems at the end of each chapter which supplement the material

Download or read book Glasses and the Vitreous State written by Jerzy Zarzycki and published by Cambridge University Press. This book was released on 1991-07-25 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an up-to-date and comprehensive coverage of the properties of glasses as materials and of the vitreous state in general. The broad coverage of the book includes a study of the methods of studying the structure, glass classification, and electrical, optical, thermal and mechanical properties of glasses.

Download or read book Forest Fire Research written by Universidade de Coimbra and published by . This book was released on 2010 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Properties of MgO and Al2O3 Ceramics written by W. D. Kingery and published by . This book was released on 1984 with total page 886 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ceramic Science for Materials Technologists written by I. J. McColm and published by . This book was released on 1983 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: