Download or read book Contr le actif du bruit en utilisant un r seau de transducteurs distribu s written by Petr David and published by . This book was released on 2008 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cette thèse aborde une nouvelle méthode de contrôle du bruit en utilisant des changements actifs de l'impédance acoustique sur la frontière du domaine contrôlé. Une étude multidisciplinaire, incluant l'acoustique, l'électrotechnique, le traitement du signal, le contrôle, l'informatique et la modélisation numérique, a permis la conception et la mise en œuvre d'un système efficace et robuste pour atténuer les ondes acoustiques dans une large bande de fréquences par un réseau de transducteurs électrodynamiques distribués. La loi de contrôle théorique a été initialement implémentée dans un modèle éléments finis multi-physique simplifié. Les résultats très prometteurs ont abouti à l'application expérimentale du contrôle centralisé dans un tube de Kundt. Après la validation du bon fonctionnement du dispositif, la conception et la réalisation de cellules indépendantes ont été effectuées pour implémenter le contrôle complètement décentralisé, Chacune de ces cellules possède son propre capteur, actionneur et le microcontrôleur, Une interconnexion appropriée des cellules a permis de réaliser un réseau 20 et d'appliquer l'algorithme de contrôle spatialement distribué, Pour implémenter l'opérateur spatial, chaque cellule nécessite les signaux de cellules voisines. Ce réseau a été implémenté sur deux parois d'un tube de section rectangulaire et le comportement prévu a été de nouveau validé expérimentalement. La robustesse, l'efficacité, la simplicité numérique ainsi q la stabilité de cette nouvelle stratégie montrent le grand potentiel de la méthode et encouragent de nouveaux efforts pour améliorer ce système actif de contrôle du bruit pour une application future dans des turboréacteurs d'avions.
Download or read book OPTIMISATION DU PLACEMENT DES ACTIONNEURS ET DES SENSEURS DANS UN PROBLEME DE CONTROLE ACOUSTIQUE ACTIF APPLICATION AUX TRANSFORMATEURS ELECTRIQUES written by Thierry Martin and published by . This book was released on 1996 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: EN CONTROLE ACTIF, L'OPTIMISATION DU POSITIONNEMENT DES TRANSDUCTEURS REPRESENTE UN AXE DE RECHERCHE IMPORTANT ET INCONTOURNABLE. LE BUT DE L'ETUDE EST DE REPONDRE A LA QUESTION SUIVANTE: COMBIEN DE TRANSDUCTEURS DOIT-ON UTILISER ET OU DOIT-ON LES PLACER POUR CONCEVOIR UN SYSTEME DE CONTROLE ACTIF REALISANT UNE ATTENUATION GLOBALE DU CHAMP RAYONNE PAR UNE SOURCE DE BRUIT, LORSQU'ON S'IMPOSE UNE CERTAINE DISTANCE ENTRE CETTE SOURCE PRIMAIRE ET LES SOURCES SECONDAIRES ? PLUTOT QUE L'APPROCHE EMPIRIQUE COMMUNEMENT UTILISEE CONSISTANT A REPARTIR UNIFORMEMENT SOURCES ET SENSEURS AUTOUR DE LA SOURCE PRIMAIRE, NOUS AVONS MONTRE QU'UNE METHODE MIXTE UTILISANT UN MODELE DU CHAMP PRIMAIRE ET DES ALGORITHMES DE RECHERCHE SELECTIVE POUVAIT CONDUIRE A UNE OPTIMISATION DU PROBLEME. L'OBJECTIF EST DE RESOUDRE UN PROBLEME DE CONTROLE ACOUSTIQUE ACTIF DE SOURCES DE BRUIT RAYONNANT EN ESPACE LIBRE. L'APPROCHE QUE NOUS PROPOSONS CONSISTE A MODELISER LE CHAMP PRIMAIRE A ATTENUER EN UTILISANT DES FONCTIONS HARMONIQUES SPHERIQUES. L'IDENTIFICATION DE CES FONCTIONS AU RAYONNEMENT DE SOURCES MULTIPOLAIRES PERMET ALORS DE DETERMINER DE MANIERE NATURELLE UN ENSEMBLE DE SOURCES DE CONTRE-BRUIT. LA DEUXIEME PARTIE DE LA METHODE CONSISTE A REDUIRE LE NOMBRE DE SENSEURS D'ERREUR ET A OPTIMISER LEURS POSITIONS EN UTILISANT DES ALGORITHMES DE RECHERCHE SELECTIVE APPELES ALGORITHMES GENETIQUES. CES ALGORITHMES, ISSUS DE LA BIOLOGIE, SONT BASES SUR LES MECANISMES DE LA SELECTION NATURELLE ET DE LA GENETIQUE, MELES A DES TECHNIQUES ALEATOIRES. ILS PERMETTENT DE TROUVER, DANS LE CAS DE PROBLEMES NON CONVEXES ET A GRAND NOMBRE DE DEGRE DE LIBERTE, UNE SOLUTION PROCHE DE L'OPTIMALE EN UN TEMPS DE CALCUL ECONOMIQUE. DES ESSAIS EN SALLE ANECHOIQUE PERMETTENT DE TESTER L'EFFICACITE DE LA METHODE SUR DES SOURCES DE BRUIT REELLES DE PETITES DIMENSIONS (ASSOCIATIONS DE HAUT-PARLEURS) OU ETENDUES (TRANSFORMATEURS ELECTRIQUES INDUSTRIELS). LES CONFIGURATIONS D'ACTIONNEURS ET DE SENSEURS D'ERREUR ISSUES DES SIMULATIONS NUMERIQUES UTILISANT LE CHAMP PRIMAIRE EXPERIMENTAL SONT ALORS TESTEES EN TEMPS REEL. LA MESURE DU CHAMP AVEC ET SANS CONTROLE PERMET ALORS D'EVALUER L'EFFICACITE DU SYSTEME DE CONTROLE ACTIF ET DE QUANTIFIER LA REDUCTION DE BRUIT OBTENUE.
Download or read book Digital Holography written by Pascal Picart and published by John Wiley & Sons. This book was released on 2013-01-24 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a substantial description of the principles and applications of digital holography. The first part of the book deals with mathematical basics and the linear filtering theory necessary to approach the topic. The next part describes the fundamentals of diffraction theory and exhaustively details the numerical computation of diffracted fields using FFT algorithms. A thorough presentation of the principles of holography and digital holography, including digital color holography, is proposed in the third part. A special section is devoted to the algorithms and methods for the numerical reconstruction of holograms. There is also a chapter devoted to digital holographic interferometry with applications in holographic microscopy, quantitative phase contrast imaging, multidimensional deformation investigations, surface shape measurements, fluid mechanics, refractive index investigations, synthetic aperture imaging and information encrypting. Keys so as to understand the differences between digital holography and speckle interferometry and examples of software for hologram reconstructions are also treated in brief. Contents 1. Mathematical Prerequisites. 2. The Scalar Theory of Diffraction. 3. Calculating Diffraction by Fast Fourier Transform. 4. Fundamentals of Holography. 5. Digital Off-Axis Fresnel Holography. 6. Reconstructing Wavefronts Propagated through an Optical System. 7. Digital Holographic Interferometry and Its Applications. Appendix. Examples of Digital Hologram Reconstruction Programs
Download or read book Dictionary of Building and Civil Engineering written by Don Montague and published by Taylor & Francis. This book was released on 1996 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dual-language dictionary lists over 20,000 specialist terms in both French and English, covering architecture, building, engineering and property terms. It meets the needs of all building professionals working on projects overseas. It has been comprehensively researched and compiled to provide an invaluable reference source in an increasingly European marketplace.
Download or read book Properties of UO2 written by J. Belle and published by . This book was released on 1957 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MRI of the Body written by Daniel Vanel and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: As with the introduction of x -ray computed tomography, much of the initial development of magnetic resonance applications tended to focus on the central nervous system. The development of magnetic resonance imaging applications to other organ systems such as the chest, abdomen, pelvis and extremities has lagged somewhat behind, awaiting technical improvements, and a broader user base. The past two years have seen a marked increase in imaging applications throughout the body, most notably the musculoskeletal system. It is in this regard, that MRI of the Body is a welcome arrival as a text which describes both basic principles of magnetic resonance ima ging and surveys the current status of magnetic resonance imaging applications throughout the body. The volume is concise, focused, clinically oriented, and abun dantly illustrated. In each organ system, the appropriate technical approach is discussed, the normal anatomic features are reviewed, and the range of pathologic appearances which may be encountered are described. The authors of the chapters provide a balanced overview of MR applications and describe both present limitations and future potential of magnetic resonance imaging applications in the organ system described.
Download or read book Combustion and Flames written by Roland Borghi and published by Editions Technips. This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Professionals working in the field of combustion may well find many points of interest, highlighted by the book's logical and global approach to phenomena, which considers mechanical, thermal and chemical aspects simultaneously. The book prioritises an understanding of the physical and chemical aspects of the phenomena, and lays particular emphasis on experimental analyses and modern numerical simulations, and on the way in which these phenomena are translated into equations.Contents: Introduction: Discovering combustion and flames. 1. Combustion thermodynamics. 2. Chemical kinetics applied to combustion. 3. Mass and energy transport by convection and diffusion. 4. Self-ignitions in closed systems. 5. Laminar flames and deflagrations. 6. Turbulent flames and deflagrations. 7. Detonation and supersonic combustion. 8. Flame ignition. 9. Combustion of liquids and sprays. 10. Pollutant emissions in combustion reactions. Index.
Download or read book Microphone Arrays written by Michael Brandstein and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to provide a single complete reference on microphone arrays. Top researchers in this field contributed articles documenting the current state of the art in microphone array research, development and technological application.
Download or read book Low Frequency Scattering written by George Dassios and published by Oxford University Press. This book was released on 2000 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scattering theory deals with the interactions of waves with obstacles in their path, and low frequency scattering occurs when the obstacles involved are very small. This book gives an overview of the subject for graduates and researchers, for the first time unifying the theories covering acoustic, electromagnetic and elastic waves.
Download or read book Biomimicry written by Janine M. Benyus and published by Harper Collins. This book was released on 2009-08-11 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Repackaged with a new afterword, this "valuable and entertaining" (New York Times Book Review) book explores how scientists are adapting nature's best ideas to solve tough 21st century problems. Biomimicry is rapidly transforming life on earth. Biomimics study nature's most successful ideas over the past 3.5 million years, and adapt them for human use. The results are revolutionizing how materials are invented and how we compute, heal ourselves, repair the environment, and feed the world. Janine Benyus takes readers into the lab and in the field with maverick thinkers as they: discover miracle drugs by watching what chimps eat when they're sick; learn how to create by watching spiders weave fibers; harness energy by examining how a leaf converts sunlight into fuel in trillionths of a second; and many more examples. Composed of stories of vision and invention, personalities and pipe dreams, Biomimicry is must reading for anyone interested in the shape of our future.
Download or read book A Practical Introduction to Borehole Geophysics written by J. Labo and published by . This book was released on 1987 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Submarine Mass Movements and Their Consequences written by Vasilios Lykousis and published by Springer Science & Business Media. This book was released on 2007-09-14 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions from leading researchers in science and engineering, this book provides a global perspective on submarine mass movements and their consequences. Authors report on new findings from fundamental as well as site-specific studies from around the world. All studies relied on the most recent technologies, including multi-beam sonar imaging techniques, 3D seismic analysis, slope stability analysis, debris flow, and tsunami modeling.
Download or read book Phase Noise and Frequency Stability in Oscillators written by Enrico Rubiola and published by Cambridge University Press. This book was released on 2010-06-10 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for academic researchers, industry practitioners, and graduate students in RF engineering and communications engineering.
Download or read book Quantum Theory of Finite Systems written by Jean-Paul Blaizot and published by Mit Press. This book was released on 1986 with total page 657 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive and pedagogical account of the various methods used in the quantum theory of finite systems, including molecular, atomic, nuclear, and particle phenomena. Covering both background material and advanced topics and including nearly 200 problems, Quantum Theory of Finite Systems has been designed to serve primarily as a text and will also prove useful as a reference in research. The first of the book's four parts introduces the basic mathematical apparatus: second quantization, canonical transformations, Wick theorems and the resulting diagram expansions, and oscillator models. The second part presents mean field approximations and the recently developed path integral methods for the quantization of collective modes. Part three develops perturbation theory in terms of both time-dependent Feynman diagrams and time-independent Goldstone diagrams. A fourth part discusses variational methods based on correlated wavefunctions, including spin correlations. The approximation schemes are formulated for fermions and bosons at eigher zero or non-zero temperature. Although the formalism developed applies to both finite and infinite systems, the book stresses those aspects of the theory that are specific to the description of finite systems. Thus special attention is given to mean field approximations, the ensuing broken symmetries, and the associated collective motions such as rotations. Conversely, some specific features of systems with infinite numbers of degrees of freedom (such as the thermodynamic limit, critical phenomena, and the elimination of ultraviolet divergencies) are deliberately omitted. Jean-Paul Blaizot and Georges Ripka are associated with the Centre d'Etudes Nucleaires de Saclay.
Download or read book Clinical Chronopharmacology written by Alain Reinberg and published by CRC Press. This book was released on 1990-07 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Periodical and predictable changes in biological susceptibility and response to a large variety of chemical agents, including drugs and food, have been documented since the early 1970s. This book provides a survey of clinically-documented research in chronopharmacology.
Download or read book Theoretical and Experimental Modal Analysis written by Nuno Manuel Mendes Maia and published by Wiley-Blackwell. This book was released on 1997 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modal analysis is a discipline that has developed considerably during the last 30 years. Theoretical and Experimental Modal Analysis is a new book on modal analysis aimed at a wide range of readers, from academics such as post-graduate students and researchers, to engineers in many industries who use modal analysis tools and need to improve their knowledge of the subject. Divided into eight chapters, the book ranges from the basics of vibration theory and signal processing to more advanced topics, including identification techniques, substructural coupling, structural modification, updating of finite element models and nonlinear modal analysis. There is also an entire chapter dedicated to vibration testing techniques. It has been written with a diversity of potential readers in mind, so that all will be able to follow the book easily and assimilate the concepts involved.
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.
