Download or read book Analyse comportementale et conception des mat riaux di lectriques Bande Interdite Photonique written by Marc Thévenot and published by . This book was released on 1999 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: EN 1986 DEBUTA LA RECHERCHE SCIENTIFIQUE SUR LES MATERIAUX A BANDE INTERDITE PHOTONIQUE (B.I.P.). CETTE RECHERCHE DEVAIT DEBOUCHER SUR DES SYSTEMES OPTIQUES ET SUR LE CONTROLE DE L'EMISSION SPONTANEE DE LA LUMIERE DANS LES LASERS A SEMI-CONDUCTEUR. AUJOURD'HUI, LES MATERIAUX A B.I.P. SUSCITENT L'INTERET DES CHERCHEURS A DES LONGUEURS D'ONDES BEAUCOUP PLUS GRANDES POUR DEVELOPPER DE NOUVEAUX SYSTEMES AUX FREQUENCES MICROONDES ET MILLIMETRIQUES. CE TRAVAIL DECRIT LES PROPRIETES ELECTROMAGNETIQUES DES MATERIAUX DIELECTRIQUES A B.I.P. IL DETAILLE LES METHODES DEVELOPPEES ET UTILISEES POUR LOCALISER LES BANDES DE FREQUENCES INTERDITES ET POUR ANALYSER LES PROPRIETES DISPERSIVES (VECTEURS D'ONDES EXCITES EN FONCTION DE LA FREQUENCE) D'ECHANTILLONS DE STRUCTURES DIELECTRIQUES PERIODIQUES EXCITEES PAR UNE SOURCE ELECTROMAGNETIQUE PHYSIQUE LOCALISEE. DEUX APPLICATIONS POUR CES MATERIAUX ONT ETE DEVELOPPEES DANS LE DOMAINE DES ANTENNES. L'UNE EST UN REFLECTEUR PARABOLIQUE DIELECTRIQUE A B.I.P.. LES RESULTATS ET LES MESURES DE SIMULATION MONTRENT QUE LE REFLECTEUR DIELECTRIQUE EST AUSSI PERFORMANT QUE LA PARABOLE METALLIQUE DE MEMES DIMENSIONS. L'AUTRE APPLICATION EST NOMMEE ANTENNE PLANAIRE A B.I.P. RAYONNANT. IL S'AGIT D'UN SYSTEME FONCTIONNANT SUR LE MODE DE DEFAUT D'UN RESEAU PERIODIQUE DIELECTRIQUE QUI, POSITIONNE SUR UN PLAN METALLIQUE PERMET D'AUGMENTER CONSIDERABLEMENT LA DIRECTIVITE DES ANTENNES IMPRIMEES.

Download or read book Mat riaux bandes interdites photoniques written by D. Cassagne and published by . This book was released on 1998 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: LES MATERIAUX A BANDES INTERDITES PHOTONIQUES SONT DES STRUCTURES DIELECTRIQUES PERIODIQUES QUI CONTROLENT LA PROPAGATION DES ONDES ELECTROMAGNETIQUES. DANS CE MEMOIRE, NOUS DECRIVONS LA METHODE DES ONDES PLANES QUI PERMET DE CALCULER LES STRUCTURES DE BANDES DES CRISTAUX PHOTONIQUES. PAR UNE ANALYSE DE LA SYMETRIE ET UNE APPROCHE PERTURBATIVE, NOUS PRECISONS LES CONDITIONS D'EXISTENCE DES BANDES INTERDITES DE BASSE ENERGIE. NOUS PROPOSONS DE NOUVELLES STRUCTURES BIDIMENSIONNELLES APPELEES GRAPHITE ET NITRURE DE BORE. GRACE A UNE METHODE DE MATRICES DE TRANSFERT, NOUS CALCULONS LA TRANSMISSION DE LA STRUCTURE GRAPHITE ET NOUS METTONS EN EVIDENCE LE ROLE FONDAMENTAL DU COUPLAGE AVEC LES MODES EXTERIEURS. NOUS ETUDIONS L'APPARITION DE MODES PERMIS DANS LA BANDE INTERDITE GRACE A L'INTRODUCTION DE DEFAUTS DANS LA PERIODICITE. ENFIN, NOUS DISCUTONS LES PROPRIETES DES OPALES CONSTITUEES DE MICRO-BILLES DE SILICE AUTO-ORGANISEES QUI SONT TRES PROMETTEUSES POUR LA FABRICATION DE CRISTAUX PHOTONIQUES TRIDIMENSIONNELS.

Download or read book Etude de la dispersion lectromagn tique dans les mat riaux di lectriques bidimensionnels written by Yannick Merle and published by . This book was released on 2003 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Depuis une vingtaine d'années, les matériaux à Bande Interdite Photonique (arrangement périodique de structure métalliques ou diélectriques) font l'objet de nombreuses études. Ils ont pour propriété d'interdire la propagation d'ondes électromagnétiques dans une certaine bande de fréquence. De telles structures peuvent aussi être utilisées pour réaliser un filtrage spatial.Ce mémoire présente une étude de matériaux à Bande Interdite Photonique infinis à deux dimensions. Ils permettent le calcul de contour de dispersion donnant accès aux différentes directions que peut prendre le vecteur d'onde dans le matériau. Puis, nous nous sommes intéressés à donner une interprétation des propriétés dispersives des matériaux périodiques. Grâce aux conditions de résonance, aux vitesses de phase et aux coefficients de transmission, nous avons montré pourquoi à certaines fréquences le matériau est totalement transparent tandis qu'à d'autres il réfléchit les ondes.

Download or read book MATERIAUX A BANDES PHOTONIQUES INTERDITES POUR L OPTIQUE ET LES TERAHERTZ REALISATION A BASE DE SILICIUM ETUDE ET CARACTERISATION written by SEBASTIAN.. ROWSON and published by . This book was released on 2000 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: UN MATERIAU A BANDE INTERDITE PHOTONIQUE OU CRISTAL PHOTONIQUE EST UNE STRUCTURE OU LA PERIODICITE SPATIALE DE LA CONSTANTE DIELECTRIQUE ENGENDRE DES PLAGES DE FREQUENCES PERMISES OU INTERDITES POUR LA PROPAGATION D'ONDES ELECTROMAGNETIQUES. TOUS LES DOMAINES DE LONGUEUR D'ONDE SONT CONCERNES, DU VISIBLE JUSQU'AUX ONDES CENTIMETRIQUES, AVEC UN EVENTAIL D'APPLICATIONS POTENTIELLES TOUT AUSSI VARIE. AU COURS DE CETTE THESE, DIFFERENTES TECHNIQUES D'ELABORATION SUR SILICIUM ONT ETE MISES AU POINT QUI PERMETTENT DESORMAIS DE REALISER DES STRUCTURES PERIODIQUES A DEUX OU TROIS DIMENSIONS AVEC UNE GRANDE SOUPLESSE QUANT A LA TAILLE ET A LA PERIODICITE DES MOTIFS. LES RESULTATS PRESENTES, NUMERIQUES ET EXPERIMENTAUX, COUVRENT AINSI PRES DE TROIS DECADES EN LONGUEUR D'ONDE EN ALLANT DU PROCHE INFRAROUGE AUX ONDES MILLIMETRIQUES. LES CRISTAUX BIDIMENSIONNELS SONT OBTENUS PAR PHOTO-ELECTROCHIMIE DU SILICIUM. CETTE TECHNIQUE DU SILICIUM MACROPOREUX DONNE DES GRAVURES PROFONDES AVEC DES FACTEURS D'ASPECTS SUPERIEURS A LA CENTAINE ET PEUT ETRE APPLIQUEE DEPUIS LE MOYEN INFRAROUGE JUSQU'AU PROCHE INFRAROUGE. CETTE TECHNIQUE A PERMIS DE DEMONTRER UNE BANDE INTERDITE PHOTONIQUE COMPLETE AUX LONGUEURS D'ONDE DES TELECOMMUNICATIONS (1,5 MICRONS). AU COURS DE CE TRAVAIL, DES CRITERES DE CHOIX POUR LES APPLICATIONS FUTURES DES CRISTAUX PHOTONIQUES BIDIMENSIONNELS ONT ETE APPORTES, NOTAMMENT PAR LA COMPARAISON DES DEUX RESEAUX, TRIANGULAIRE ET HEXAGONAL. CES CRITERES DE CHOIX SONT GENERAUX ET NE SE LIMITENT PAS AU SILICIUM MACROPOREUX. UNE TECHNIQUE DE FABRICATION PAR USINAGE MECANIQUE EST DEMONTREE POUR OBTENIR DES CRISTAUX TRIDIMENSIONNELS POUR LES ONDES MILLIMETRIQUE. CETTE TECHNIQUE A PERMIS D'ETUDIER L'INFLUENCE DES DEFAUTS INTERSTITIELS VOLONTAIREMENT INTRODUITS DANS LES STRUCTURES ET DE DEMONTRER LA POSSIBILITE DE CONTROLER DE L'EXTERIEUR LES NIVEAUX DE TRANSMISSION DE MODES DE DEFAUT.

Download or read book Contribution l tude des mat riaux Bande Interdite Photonique written by Marie-Sandrine Denis and published by . This book was released on 1998 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les matériaux à Bande Interdite Photonique (composés d'arrangements périodiques de la constante diélectrique) présentent d'intéressantes propriétés de réflexion dans une large bande de fréquence. L'introduction de défauts (rupture de la périodicité) au sein de tels matériaux conduit à l'apparition de pics de transmission à l'intérieur de la bande interdite. De telles structures peuvent être utilisées comme filtres fréquentiel ou angulaire. Ce mémoire décrit les méthodes de simulation utilisées pour la caractérisation de matériaux à BIP. Puis une étude théorique et expérimentale d'un BIP bidimensionnel diélectrique est effectuée. Les résultats expérimentaux, en parfaite concordance avec les résultats de simulation, permettent de valider les codes de calcul. Différentes applications dans le domaines des antennes imprimées sont ensuite données : 1) Antennes à réflecteur : un matériau BIP, placé sous un dipôle électrique, joue un rôle de plan réflecteur. 2) Antennes imprimées sur substrats BIP : la mise en place de matériau BIP comme substrat d'antennes permet de diminuer le rayonnement à 90°. 3)Antennes imprimées possédant un radôme BIP : la perturbation du rayonnement d'une antenne sous un radôme BIP est mise en évidence. Une antenne fort gain est obtenue en insérant un gap d'air entre l'élément rayonnant et le radôme

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 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 An Introduction to Differential Manifolds written by Jacques Lafontaine and published by Springer. This book was released on 2015-07-29 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an introduction to differential manifolds. It gives solid preliminaries for more advanced topics: Riemannian manifolds, differential topology, Lie theory. It presupposes little background: the reader is only expected to master basic differential calculus, and a little point-set topology. The book covers the main topics of differential geometry: manifolds, tangent space, vector fields, differential forms, Lie groups, and a few more sophisticated topics such as de Rham cohomology, degree theory and the Gauss-Bonnet theorem for surfaces. Its ambition is to give solid foundations. In particular, the introduction of “abstract” notions such as manifolds or differential forms is motivated via questions and examples from mathematics or theoretical physics. More than 150 exercises, some of them easy and classical, some others more sophisticated, will help the beginner as well as the more expert reader. Solutions are provided for most of them. The book should be of interest to various readers: undergraduate and graduate students for a first contact to differential manifolds, mathematicians from other fields and physicists who wish to acquire some feeling about this beautiful theory. The original French text Introduction aux variétés différentielles has been a best-seller in its category in France for many years. Jacques Lafontaine was successively assistant Professor at Paris Diderot University and Professor at the University of Montpellier, where he is presently emeritus. His main research interests are Riemannian and pseudo-Riemannian geometry, including some aspects of mathematical relativity. Besides his personal research articles, he was involved in several textbooks and research monographs.

Download or read book Aeronomy written by P. M. Banks and published by Elsevier. This book was released on 2013-09-24 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aeronomy, Part A is an attempt to make a comprehensive exposition of the processes in aeronomy, the study of composition, movement, and thermal balance of the upper regions of the planetary atmosphere. The text covers topics such as atmospheric regions and atmospheric density, the temperature and molecular mass of the atmosphere; the permanent constituents and the molecular and isotonic composition of the homosphere; and the transition from the homosphere to the heterosphere. Also covered are topics such as the temperature gradient and energies in the thermosphere, conditions at 200km and above 250km, solar radiation and ionization, and aeronomic reactions. The book is recommended for scientists, especially natural physicists, who would like to know more about the field of aeronomy and its advances.

Download or read book Waves and Vibrations in Soils written by Jean-François Semblat and published by Iuss Press. This book was released on 2009 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inequalities in Mechanics and Physics written by G. Duvant and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. We begin by giving a simple example of a partial differential inequality that occurs in an elementary physics problem. We consider a fluid with pressure u(x, t) at the point x at the instant t that 3 occupies a region Q oflR bounded by a membrane r of negligible thickness that, however, is semi-permeable, i. e., a membrane that permits the fluid to enter Q freely but that prevents all outflow of fluid. One can prove then (cf. the details in Chapter 1, Section 2.2.1) that au (aZu azu aZu) (1) in Q, t>o, -a - du = g du = -a z + -a z + -a z t Xl X X3 z l g a given function, with boundary conditions in the form of inequalities u(X,t»o => au(x,t)/an=O, XEr, (2) u(x,t)=o => au(x,t)/an?:O, XEr, to which is added the initial condition (3) u(x,O)=uo(x). We note that conditions (2) are non linear; they imply that, at each fixed instant t, there exist on r two regions r~ and n where u(x, t) =0 and au (x, t)/an = 0, respectively. These regions are not prescribed; thus we deal with a "free boundary" problem.

Download or read book Mechanics of Generalized Continua written by Gérard A. Maugin and published by Springer Science & Business Media. This book was released on 2010-03-24 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: In their 1909 publication Théorie des corps déformables, Eugène and François Cosserat made a historic contribution to materials science by establishing the fundamental principles of the mechanics of generalized continua. The chapters collected in this volume showcase the many areas of continuum mechanics that grew out of the foundational work of the Cosserat brothers. The included contributions provide a detailed survey of the most recent theoretical developments in the field of generalized continuum mechanics and can serve as a useful reference for graduate students and researchers in mechanical engineering, materials science, applied physics and applied mathematics.

Download or read book Mathematical Methods for Wave Phenomena written by Norman Bleistein and published by Academic Press. This book was released on 2012-12-02 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computer Science and Applied Mathematics: Mathematical Methods for Wave Phenomena focuses on the methods of applied mathematics, including equations, wave fronts, boundary value problems, and scattering problems. The publication initially ponders on first-order partial differential equations, Dirac delta function, Fourier transforms, asymptotics, and second-order partial differential equations. Discussions focus on prototype second-order equations, asymptotic expansions, asymptotic expansions of Fourier integrals with monotonic phase, method of stationary phase, propagation of wave fronts, and variable index of refraction. The text then examines wave equation in one space dimension, as well as initial boundary value problems, characteristics for the wave equation in one space dimension, and asymptotic solution of the Klein-Gordon equation. The manuscript offers information on wave equation in two and three dimensions and Helmholtz equation and other elliptic equations. Topics include energy integral, domain of dependence, and uniqueness, scattering problems, Green's functions, and problems in unbounded domains and the Sommerfeld radiation condition. The asymptotic techniques for direct scattering problems and the inverse methods for reflector imaging are also elaborated. The text is a dependable reference for computer science experts and mathematicians pursuing studies on the mathematical methods of wave phenomena.

Download or read book Minimum competence in scientific English written by Sue Blattes and published by L'Editeur : EDP Sciences. This book was released on 2003 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cet ouvrage, devenu célèbre sous son sigle MCSE, a déjà été utilisé par plus de 50 000 étudiants, chercheurs, professionnels. L'objectif est de lire et écrire des textes en anglais scientifique avec facilité et pertinence. L'ouvrage est conçu pour que l'apprenant devienne un véritable utilisateur de l'anglais. La méthode originale repose sur l'analyse des fonctions et structures nécessaires : measurement, frequency, comparison, modification, link words, time, cause and consequence, hypothesis, modality, purpose and process, impersonal forms, compound nouns and adjectives. Dans chaque unit, des tests d'auto-évaluation permettent de se situer et de construire son parcours de formation, d'abord en définissant ses objectifs à l'aide des key points et du lexis, puis, de façon plus personnalisée, en puisant dans les examples in context, checkpoints (back to basics, word web), web search, FAQs... MCSE est l'outil de base d'une méthode qui comprend aussi d'autres outils dans la même collection (Listening Comprehension for Scientiflc English et Speaking Skills in Scientitic English). L'ouvrage est destiné à tout apprenant de niveau baccalauréat qui désire acquérir une réelle compétence dans l'écriture et la lecture de textes en anglais scientifique.

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 Phononic Crystals written by Vincent Laude and published by Walter de Gruyter GmbH & Co KG. This book was released on 2015-09-14 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phononic crystals are artificial periodic structures that can alter efficiently the flow of sound, acoustic waves, or elastic waves. They were introduced about twenty years ago and have gained increasing interest since then, both because of their amazing physical properties and because of their potential applications. The topic of phononic crystals stands as the cross-road of physics (condensed matter physics, wave propagation in inhomogeneous and periodic media) and engineering (acoustics, ultrasonics, mechanical engineering, electrical engineering). Phononic crystals cover a wide range of scales, from meter-size periodic structures for sound in air to nanometer-size structures for information processing or thermal phonon control in integrated circuits. Phononic crystals have a definite relation with the topic of photonic crystals in optics. The marriage of phononic and photonic crystals also provides a promising structural basis for enhanced sound and light interaction. As the topic is getting popular, it is nowadays presented and discussed at various international conferences. After the first ten years during which the topic has remained mainly theoretical with a few proof-of-concept demonstrations in the literature, the evolution has been towards applications, instrumentation, and novel designs. The physical explanations for various effects are now well understood and efficient numerical methods and analysis tools have been developed. The book contains a comprehensive set of finite element model (FEM) scripts for solving basic phononic crystal problems. The scripts are short, easy to read, and efficient, allowing the reader to generate for him(her)self band structures for 2D and 3D phononic crystals, to compute Bloch waves, waveguide and cavity modes, and more.

Download or read book Popular Astronomy written by Camille Flammarion and published by . This book was released on 1894 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt: