Download or read book R ponse d une plaque coupl e une cavit acoustique excit e par un coulement turbulent written by Emmanuel Levitte and published by . This book was released on 2008 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mod lisation de la r ponse lectro acoustique d une structure coupl e une cavit en pr sence d un coulement turbulent written by Damien Leclercq and published by . This book was released on 1999 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Etude num rique du comportement vibro acoustique d un syst me plaque cavit dans un coulement uniforme pour diff rents types d excitation written by Franck Sgard and published by . This book was released on 1995 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: La réduction du bruit émis et transmis par les structures en mouvement excitées mécaniquement, aérodynamiquement ou acoustiquement, intéresse de nombreux secteurs industriels tels que l'automobile, l'aéronautique et la marine. Les mécanismes physiques qui régissent le comportement vibra-acoustique de structures se déplaçant dans des écoulements font cependant intervenir des mécanismes de couplage fluide-structure très complexes et difficiles à modéliser, notamment dans le cas d'excitations par couches limites turbulentes. Les structures courantes en mouvement, peuvent être souvent modélisées par des systèmes constitués par une structure vibrante, couplée à une cavité. Dans ce travail, on propose une formulation pour estimer l'influence d'un écoulement uniforme sur la réponse vibra-acoustique basses fréquences d'un système particulier: une plaque bafflée, encastrée, immergée dans un écoulement uniforme et couplée à une cavité et excitée mécaniquement, acoustiquement ou par une couche limite turbulente. Les originalités de cette étude sont multiples: prise en compte des effets liés au mouvement du fluide extérieur à la cavité, caractère inédit de la formulation intégrale prenant en compte l'écoulement, caractère général de la formulation, basée sur une méthode mixte éléments finis-éléments de frontières, permettant le traitement de plaques et de cavités de formes quelconques (pourvu que la cavité comporte une face plane), mise en évidence des effets de l'écoulement uniforme en termes de masse, d'amortissement et de raideur ajoutés, et enfin puissance des algorithmes intervenant dans l'implantation numérique de la formulation. Les résultats montrent que l'écoulement a des effets sensibles pour des vitesses d'écoulement importantes lorsque le fluide convecteur est de l'air (Mach supérieur à 0.4), et relativement faibles lorsque le fluide convecteur est de l'eau (vitesse supérieure à quelques m/ s). L'ampleur des changements dans les niveaux des indicateurs dépend aussi du type d'excitation.
Download or read book Rayonnement acoustique d une cavit rectangulaire soumise un coulement turbulent written by David Mas (auteur en mécanique des fluides).) and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lorsqu'une cavité est soumise à un écoulement turbulent, de forts niveaux sonores peuvent être engendrés. Pur évaluer les niveaux de pression acoustique en champ lointain une approche en deux étapes est proposée. Tout d'abord, des simulations numériques de l'écoulement, considéré comme incompressible, sont réalisées à partir des équations de Reynolds complétées par des lois de fermeture élémentaires (k-c, sgs Smagorinsky). En outre, des visualisations et des mesures de pression fluctuante pariétale sont réalisées en tunnel hydraulique ; ces mesures ne sont pas suffisamment exhaustives pour conduire à une validation totale des modèles numériques dont on a pu cependant repérer certaines lacunes, En conséquence, on a plutôt cherché à combiner les résultats issus de ces modèles et les données expérimentales pour constituer des données d'entrée cohérentes du modèle acoustique correspondant à la deuxième étape. Ensuite, un modèle acoustique simple, fondé sur l'analogie de Lighthill, permet le calcul de la fréquence et de l'amplitude de pression acoustique en champ lointain. Pour tester ce modèle, on s'appuie par ailleurs sur des mesures acoustiques en champ lointain réalisées dans une soufflerie anéchoïque. Le modèle acoustique fournit un ordre de grandeur très satisfaisant des niveaux de pression acoustique mesurés. Enfin, un développement annexe de ce travail a consisté à raffiner la typologie des écoulements dans les cavités lorsque le rapport géométrique L/H augmente. On distingue alors trois configurations d'écoulement. Pour une cavité carrée, l'écoulement est quasi-2D. Pour un rapport géométrique de l'ordre de 1,5, l'écoulement fortement 3D se caractérise par une ondulation transverse de la zone de recirculation principale. Enfin, pour des rapports géométriques supérieurs à 2, la zone de recirculation se concentre sur la partie aval de la cavité ; l'écoulement est alors 2D.
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 Dictionary of French and English English and French written by John Bellows and published by Legare Street Press. This book was released on 2022-10-27 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Download or read book Advances in Rotorcraft Technology written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Flight Vehicle Integration Panel. Symposium and published by . This book was released on 1997 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Hydroinformatics written by Philippe Gourbesville and published by Springer. This book was released on 2015-08-21 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a collection of extended papers based on presentations given during the SIMHYDRO 2014 conference, held in Sophia Antipolis in June 2014. It focuses on the modeling and simulation of fast hydraulic transients, on 3D modeling, and on uncertainties and multiphase flows. The book explores both the limitations and performance of current models and presents the latest developments based on new numerical schemes, high-performance computing, multiphysics and multiscale methods, and better interaction with field or scale model data. It addresses the interests of practitioners, stakeholders, researchers and engineers active in this field.
Download or read book Historical Dictionary of Iran written by John Henry Lorentz and published by Historical Dictionaries of Asia, Oceania, and the Middle East. This book was released on 2007 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an overview of specific events, movements, people, political and social groups, places, trends, and chronology. Allows for considerable exploration of a number of historical and contemporary topics and issues. The modern period, defined as 1800-present, is covered extensively.
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 Historical Dictionary of Pakistan written by Shahid Javed Burki and published by . This book was released on 1999 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pakistan is unlike most other countries in the emerging world. It is one of the two nations – the other being the state of Israel – founded on the basis of religion. Although it was created to provide a homeland for the Muslim community of British India, in its original form it was able to accommodate only about half of the people of Islamic faith who lived in the subcontinent. Pakistan’s birth in 1947 resulted in one of the largest movements of people in human history when some 14 million people left their homes, with 8 million Muslims leaving India for what is now Pakistan and 6 million Hindus and Sikhs moving in the opposite direction. This was the first large-scale incidence of ethnic cleansing the world was to witness. --
Download or read book Advances in Acoustic Microscopy written by Andrew Briggs and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second volume of Advances in Acoustic Microscopy. It continues the aim of presenting applications and developments of techniques that are related to high-resolution acoustic imaging. We are very grateful to the authors who have devoted considerable time to preparing these chapters, each of which describes a field of growing importance. Laboratories that have high-performance acoustic microscopes are frequently asked to examine samples for which the highest available resolution is not necessary, and the ability to penetrate opaque layers is more significant. Such applications can be thought of as bridging the gap be tween acoustic microscopy at low gigahertz frequencies, and on the one hand nondestructive testing of materials at low megahertz frequencies and on the other hand medical ultrasonic imaging at low megahertz frequencies. Commercial acoustic microscopes are becoming increasingly available and popular for such applications. We are therefore delighted to be able to begin the volume with chapters from each of those two fields. The first chapter, by Gabriele Pfannschmidt, describes uses of acoustic microscopy in the semiconductor industry. It provides a splendid balance to the opening chapter of Volume 1, which came from a national research center, being written from within a major European electronics industry itself. Dr Pfann schmidt describes the use of two quite different types of acoustic microscopes, and points out the advantages of each for specific purposes.
Download or read book Transport Phenomena in Membranes written by N. Lakshminarayanaiah and published by . This book was released on 1969 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrically Small Superdirective and Superconducting Antennas written by R. C. Hansen and published by John Wiley & Sons. This book was released on 2006-06-19 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: A seminal reference to electrically small antennas for today's wireless and Wi-Fi world This book is dedicated to the challenges posed by electrically small antennas and their solutions. Electrically small antennas have characteristics that limit performance: low radiation resistance, high reactance, low efficiency, narrow bandwidth, and increased loss in the matching network. Most of these limitations are shared by two other classes of antennas: superdirective and superconducting antennas. All three classes of antennas are thoroughly treated in three interrelated parts: * Part One, Electrically Small Antennas, begins with a discussion of the fundamental limitations of bandwidth and matching, then provides detailed design information on loaded whips and dipoles, ferrite loops, patches with unusual substrates, and dielectric resonator antennas. In addition to exploring designs that work, the author sets forth antenna designs that are based on good physics yet are poor performers, as well as designs with both poor underlying physics and poor performance. * Part Two, Superdirective Antennas, sets forth basic capabilities and limitations of superdirective antennas, both apertures and arrays, and investigates bandwidth, efficiency, and tolerances. The author explores the magnification of intrinsic matching circuit loss due to a large mismatch and evaluates the recent and promising non-Foster matching circuits. * Part Three, Superconducting Antennas, reviews superconductivity concepts and new principles for dipole, loop, and patch antennas. The author concludes with a discussion of superconducting delay lines for wideband phased array steering. Throughout the book, the author provides readers with a historical perspective, setting forth what has been investigated, what works, and what does not. Each part has its own author index and a list of references to help readers continue their explorations of particular topics.With the explosive demand for wireless and Wi-Fi, this seminal reference is essential reading for all antenna professionals and is recommended as a graduate-level course book.
Download or read book Earth Resources Satellites written by United States. Congress. Senate. Committee on Aeronautical and Space Sciences and published by . This book was released on 1974 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics of Satellites 1969 written by Bruno Morando and published by Springer. This book was released on 2012-02-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the proceedings of a symposium on Dynamics of satellites which took place in Prague in May 1969 during the twelfth COSPAR meeting. This symposium was sponsored by the International Astronomical Union, the International Association of Geodesy, the International Union of Theoretical and Applied Mechanics and COSPAR (Committee on Space Research). The organizing committee was composed of Dr. KOVALEVSKY chair man, Dr. Yu. V. BATRAKOV representing IAU, Dr. A. H. COOK for lAG, Dr. D. KING-HELE for COSPAR, Prof. M. Roy for IUTAM and Dr. ROSENBERG. I wish to take advantage of the opportunity to thank, on behalf of all the participants, the organizing committee members, Prof. BUCHAR, Dr. RAJSK:I and Dr. SEHNAL, for the kindness and efficiency of their welcome. The interpreters who translated with virtuosity during the whole symposium also deserve our gratitude. I am grateful also for the care and skill with which Springer-Verlag has printed this volume.
Download or read book Exact and Approximate Controllability for Distributed Parameter Systems written by Roland Glowinski and published by . This book was released on 2008-03-20 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough mathematical analysis of controllability problems with a detailed investigation of methods for solving them numerically.
