Author: SEN.. WANG Publisher: ISBN: Category : Languages : fr Pages :
Book Description
L'INTERACTION ACOUSTO-OPTIQUE EST UTILISE EN CONCURRENCE AVEC DES SYSTEMES PUREMENT ELECTRONIQUES, POUR L'ANALYSE SPECTRALE, EN TEMPS REEL, DE SIGNAUX RADIOELECTRIQUES. NOUS AVONS CONDUIT UNE ETUDE THEORIQUE APPROFONDIE SUR L'OPTIMISATION DES PROCESSEURS ACOUSTOOPTIQUES (EFFICACITE, BANDE PASSANTE, RESOLUTION ET DYNAMIQUE). NOUS PRESENTONS UNE NOUVELLE FORMULATION DU COUPLAGE ELECTROMECANIQUE DU TRANSDUCTEUR PIEZO-ELECTRIQUE ET PROPOSONS UN MODELE TRIDIMENSIONNEL DE LA GENERATION ET DE LA PROPAGATION DES ONDES DE VOLUME DANS UN TRANSDUCTEUR RELIE A UN CRISTAL DE PROPAGATION. LA QUANTIFICATION DES MODES PARASITES ET L'ADAPTATION DES IMPEDANCES MECANIQUES SONT AINSI DETERMINEES, EN PARTICULIER, DANS LES STRUCTURES LINBO#3 (Y+36)-GAP(110) ET LINBO#3 (Y+163)-LINBO#3 (Y+115). NOUS AVONS PU PRECISER QUE LES PARAMETRES DE REALISATION D'UNE CELLULE DE BRAGG IGHZ BANDE ET DE RESOLUTION DE 1000 POINTS. DEUX DE CES PROCESSEURS ONT ETE REALISES AVEC LA SOCIETE THOMSON SINTRA. ILS CONSTITUENT LE CUR D'UN PROTOTYPE DE SPECTROMETRE MINIATURE DEDIE A DES APPLICATIONS SPATIALES DANS LE DOMAINE DE LA RADIOASTRONOMIE SUBMILLIMETRIQUE
Author: Philippe Goutin Publisher: ISBN: Category : Languages : fr Pages : 34
Book Description
Les filtres acousto-optiques transversaux et leurs applications sont maintenant bien connus. Parmi ceux-ci, le convoluteur acousto-optique a été l'objet d'un intérêt particulier. Le travail a consisté en la conception d'algorithmes et la réalisation d'un système digital de pilotage adapté à la structure de ce composant en vue de traitements numériques du signal. Nous rappelons d'abord le principe du convoluteur acousto-optique. Les problèmes de synchronisation entre l'émission des différents signaux et la mémorisation du signal de convolution après détection sont ensuite présentés. Ces contraintes ont débouché sur plusieurs algorithmes possibles. Le choix de l'un d'entre eux est justifié par le meilleur compromis performances/complexité. Il en découle la structure du pilote, conçu à partir de circuits PLD. L'évaluation des caractéristiques du système a été obtenue à partir des résultats expérimentaux, dont nous donnons quelques exemples : autoconvolution, filtrage F.I.R., corrélation, codes de Golay et multiplication matricielle. Pour terminer, nous présentons des améliorations et extensions possibles : augmentation de la longueur des filtres, optimisation de la vitesse de calcul par double échantillonnage et emploi de réseaux logiques à plus haute densité d'intégration, traitement multicanal.
Author: Alexander V. Sergienko Publisher: CRC Press ISBN: 1420026607 Category : Science Languages : en Pages : 248
Book Description
All current methods of secure communication such as public-key cryptography can eventually be broken by faster computing. At the interface of physics and computer science lies a powerful solution for secure communications: quantum cryptography. Because eavesdropping changes the physical nature of the information, users in a quantum exchange can easily detect eavesdroppers. This allows for totally secure random key distribution, a central requirement for use of the one-time pad. Since the one-time pad is theoretically proven to be undecipherable, quantum cryptography is the key to perfect secrecy. Quantum Communications and Cryptography is the first comprehensive review of the past, present, and potential developments in this dynamic field. Leading expert contributors from around the world discuss the scientific foundations, experimental and theoretical developments, and cutting-edge technical and engineering advances in quantum communications and cryptography. The book describes the engineering principles and practical implementations in a real-world metropolitan network as well as physical principles and experimental results of such technologies as entanglement swapping and quantum teleportation. It also offers the first detailed treatment of quantum information processing with continuous variables. Technologies include both free-space and fiber-based communications systems along with the necessary protocols and information processing approaches. Bridging the gap between physics and engineering, Quantum Communications and Cryptography supplies a springboard for further developments and breakthroughs in this rapidly growing area.
Author: Xavier Begaud Publisher: John Wiley & Sons ISBN: 1118586573 Category : Technology & Engineering Languages : en Pages : 217
Book Description
Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recognized studies.
Author: Alain Sibille Publisher: Academic Press ISBN: 0123821959 Category : Technology & Engineering Languages : es Pages : 385
Book Description
Foreword from Arogyaswami Paulraj, Professor (Emeritus), Stanford University (USA) - The first book to show how MIMO principles can be implemented in today's mobile broadband networks and components - Explains and solves some of the practical difficulties that arise in designing and implementing MIMO systems - Both theory and implementation sections are written in the context of the most recent standards: IEEE 802.11n (WiFi); IEEE 802.16 (WIMAX); 4G networks (3GPP/3GPP2, LTE)
Author: Roberto Verdone Publisher: Springer Science & Business Media ISBN: 144712314X Category : Computers Languages : en Pages : 696
Book Description
Reporting the findings of COST 2100, a major European intergovernmental project, this volume offers system designers a good source of guidelines based on channel characterization and measurement-based modeling, as well as worthwhile ideas for future research.
Author: Michael Möser Publisher: Springer Science & Business Media ISBN: 3540927239 Category : Technology & Engineering Languages : en Pages : 540
Book Description
Suitable for both individual and group learning, Engineering Acoustics focuses on basic concepts and methods to make our environments quieter, both in buildings and in the open air. The author’s tutorial style derives from the conviction that understanding is enhanced when the necessity behind the particular teaching approach is made clear. He also combines mathematical derivations and formulas with extensive explanations and examples to deepen comprehension. Fundamental chapters on the physics and perception of sound precede those on noise reduction (elastic isolation) methods. The last chapter deals with microphones and loudspeakers. Moeser includes major discoveries by Lothar Cremer, including the optimum impedance for mufflers and the coincidence effect behind structural acoustic transmission. The appendix gives a short introduction on the use of complex amplitudes in acoustics.
Author: Francine Krief Publisher: John Wiley & Sons ISBN: 1118580893 Category : Technology & Engineering Languages : en Pages : 235
Book Description
This book focuses on green networking, which is an important topic for the scientific community composed of engineers, academics, researchers and industrialists working in the networking field. Reducing the environmental impact of the communications infrastructure has become essential with the ever increasing cost of energy and the need for reducing global CO2 emissions to protect our environment. Recent advances and future directions in green networking are presented in this book, including energy efficient networks (wired networks, wireless networks, mobile networks), adaptive networks (cognitive radio networks, green autonomic networking), green terminals, and industrial research into green networking (smart city, etc.).
Author: SEN.. WANG
Author: Philippe Goutin
Author: Philippe Goutin
Author: Alexander V. Sergienko
Author: Xavier Begaud
Author: Alain Sibille
Author: Roberto Verdone
Author: Eric Brousseau
Author: Michael Möser
Author: Francine Krief