Download or read book MODELISATION ET COMPRESSION D UN SIGNAL ULTRASONORE A SCAN written by SEBASTIEN.. MAIZY and published by . This book was released on 2000 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'OBJECTIF DE CETTE THESE EST DE MODELISER EN VUE D'UNE COMPRESSION UN SIGNAL ULTRASONORE A-SCAN. POUR DETECTER DES DEFAUTS DANS DES MATERIAUX, DES TECHNIQUES SONT MISES AU POINT TELLES QUE LE CONTROLE NON DESTRUCTIF ULTRASONORE. MAIS LES SIGNAUX RECUPERES (A-SCAN ET B-SCAN) PRESENTENT LE DOUBLE INCONVENIENT D'ETRE LOURDS AU STOCKAGE ET DIFFICILES A INTERPRETER. LE BUT ICI N'EST PAS D'INTERPRETER LE SIGNAL (ET DE DIMENSIONNER LES DEFAUTS), MAIS DE LE COMPRIMER TOUT EN CONSERVANT L'INFORMATION RELATIVE AUX DEFAUTS. POUR CE FAIRE, NOUS CLASSIFIERONS LES METHODES DE COMPRESSION EN DEUX CATEGORIES : LES METHODES GENERIQUES (QUI PEUVENT S'APPLIQUER A N'IMPORTE QUEL SIGNAL DISCRET : LEMPEL ZIV, JPEG, TRANSFORMEE DE KARHUNEN LOEVE ET EN ONDELETTES, ) ET LES METHODES DEDIEES (METHODES QUI TIENNENT COMPTE DE LA SPECIFICITE ULTRASONORE DU SIGNAL). LES METHODES GENERIQUES TESTEES SONT LES PLUS COURAMMENT REPANDUES DANS LA LITTERATURE ET NOUS PERMETTENT D'ARRIVER A DES PREMIERS RESULTATS DE COMPRESSION (50% POUR LES METHODES SANS PERTE, 90% AVEC PERTE). MAIS ELLES PRESENTENT L'INCONVENIENT DE DEVOIR RECONSTITUER LE SIGNAL POUR L'INTERPRETER. LES COMPRESSIONS DEDIEES SE PRESENTENT SOUS DEUX FORMES : D'ABORD IL S'AGIRA D'AMELIORER LES COMPRESSIONS GENERIQUES EN LES DEDIANT A NOS SIGNAUX (METHODES QUI PRESENTENT ENCORE L'INCONVENIENT DE DEVOIR REPASSER PAR L'ETAPE D'UNE RECONSTRUCTION TEMPORELLE DU SIGNAL COMPRIME), PUIS DANS UN DEUXIEME TEMPS DE MODELISER LE SIGNAL DE MANIERE A NE CONSERVER QUE LES PARAMETRES QUI SERONT DIRECTEMENT RELIES A L'IDENTIFICATION DU DEFAUT. EN CONCLUSION NOUS MONTRERONS L'INTERET DU MODELE PARAMETRIQUE QUI NE SE JUSTIFIE QUE SI L'ON ARRIVE A IDENTIFIER LE DEFAUT DEPUIS LE JEU DE PARAMETRES SANS PASSER PAR LA RECONTRUCTION DU SIGNAL (COMPRESSION > 95%), ET METTRONS EN EVIDENCE LA METHODE QUI A L'HEURE ACTUELLE EST LA PLUS EFFICACE.
Download or read book Modelisation parametrique et detection de ruptures en traitement du signal ultrasonore written by Denis Kouamé and published by . This book was released on 1996 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'UTILISATION DES ULTRASONS DANS LES DOMAINES INDUSTRIEL ET MEDICAL REVET UNE IMPORTANCE CAPITALE A L'HEURE ACTUELLE. DE NOMBREUSES ETUDES ONT DE CE FAIT ETE MENEES POUR DIMINUER LES COUTS ET AMELIORER LES PERFORMANCES DES TRANSDUCTEURS QUI SERVENT A LES GENERER ET A LES DETECTER. DANS BIEN DES CAS, LE TRAITEMENT DU SIGNAL INDISPENSABLE ASSOCIE DEMEURE SOMMAIRE ET INADAPTE AUX CONTRAINTES DE TEMPS REEL ET A LA PRISE EN COMPTE DE NON-STATIONNARITES. L'OBJET DE CETTE THESE EST L'EXTRACTION DE CARACTERISTIQUES DE SYSTEMES PHYSIQUES, A PARTIR DE SIGNAUX DOPPLER ULTRASONORES. DEUX APPLICATIONS SPECIFIQUES VONT MOTIVER CETTE ETUDE. 1) LA MESURE DE LA VITESSE D'ECOULEMENT D'UN FLUIDE. SA FINALITE EST D'AMELIORER LA PRECISION DES METHODES USUELLES UTILISEES DANS LES APPAREILS DE MESURE DE FLUX (TELS QUE LES DEBITMETRES) CONVENTIONNELS, AINSI QUE LEURS APTITUDES A SUIVRE LES NON-STATIONNARITES. 2) LA DETECTION D'EMBOLES, C'EST-A-DIRE LA DETECTION DU PASSAGE DE PARTICULES ETRANGERES A LA CONSTITUTION NORMALE DU SANG, MAIS TRANSPORTEES LORS DE SON ECOULEMENT. LE BUT EST ICI DE DETECTER, EN TEMPS REEL ET DE FACON AUSSI CERTAINE QUE POSSIBLE, LE PASSAGE DE MICRO-EMBOLES QUI PEUVENT ETRE A L'ORIGINE DE GRAVES PATHOLOGIES. POUR RESOUDRE CES DEUX PROBLEMES, NOUS UTILISONS DES APPROCHES REPOSANT SUR L'IDENTIFICATION PARAMETRIQUE. AGIN DE SURMONTER LES INCONVENIENTS DES METHODES D'ESTIMATION PARAMETRIQUE CONVENTIONNELLE DES MOINDRES CARRES, NOUS PRESENTONS UNE NOUVELLE APPROCHE FONDEE SUR LA PRISE EN COMPTE DES CONNAISSANCES PARTIELLES DISPONIBLES PENDANT L'ESTIMATION ET SUR L'UTILISATION DE L'OPERATEUR DELTA. LE NOUVEL ESTIMATEUR, UTILISE CONJOINTEMENT AVEC UNE PROCEDURE D'ESTIMATION DE LA FREQUENCE DOPPLER FONDEE SUR LA DECOMPOSITION DE LA DENSITE SPECTRALE DE PUISSANCE, A PERMIS D'APPORTER UNE REPONSE EN TERME DE RAPIDITE ET DE PRECISION AU PROBLEME DE LA VELOCIMETRIE, DANS LE CAS DE SIGNAUX FORTEMENT NON STATIONNAIRES. LE PROBLEME DE LA DETECTION D'EMBOLES A ETE POSE DANS LE CADRE DE LA DETECTION DE RUPTURES DE MODELES. PLUSIEURS PROCEDURES SONT AINSI COMPAREES, ET LA COMPENSATION DE LA RUPTURE REVISITEE. LA VALIDATION DES METHODES EMPLOYEES EST REALISEE A PARTIR D'UNE PART, DE SIMULATIONS ET D'AUTRE PART, DE SIGNAUX REELS.
Download or read book Mod lisation de signaux d chographie ultrasonore provenant de d fauts de type plan et de type volumique written by Nazir Chebbo and published by . This book was released on 1996 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Un modèle en géométrie bidimensionnelle de l'interaction soit d'un faisceau ultrasonore avec un défaut plan pour simuler une fissure de fatigue dans un solide, soit d'une seule onde plane avec un défaut volumique simple (un cylindre de section circulaire et d'extension infinie) pour simuler des inclusions dans un solide élastique a été développe, dans le but d'obtenir les signaux temporels issus du défaut. La première partie de ce travail a consiste à modéliser les signaux échographiques diffractes issus de l'interaction d'un faisceau ultrasonore avec un défaut plan. Parmi les méthodes existantes pour traiter l'interaction d'une onde incidente avec ce défaut, nous avons choisi d'utiliser la théorie géométrique de la diffraction. Le formalisme du spectre angulaire applique à une variable vectorielle dans un solide (le cas fluide n'étant qu'un cas particulier du solide) a été étudie pour décrire la propagation et la transmission a travers une interface plane. Le faisceau ultrasonore incident est émis dans un fluide. Le défaut considère est dans un solide. Le vecteur spectre angulaire est décompose en milieu solide et fluide. Un certain nombre de problèmes numériques ont été résolus tels que l'échantillonnage de la phase du spectre angulaire et le choix de l'incrément spatial a l'interface solide-fluide. Le modèle développé permet de reconstituer le signal échographique issu du champ diffracte par les bords d'une fissure. Des signaux échographiques issus du modèle montrent que ce dernier permet de retrouver d'une part l'inversion de polarité entre les deux bords de la fissure, et d'autre part que le premier écho a une forme comparable à celle de la dérivée première du signal émis par le transducteur. Une comparaison avec des résultats simules et expérimentaux obtenus au cea a enfin permis la validation du logiciel. La deuxième partie de ce travail a consiste a modéliser les signaux diffuses issus de l'interaction d'une onde plane incidente avec un cylindre de section circulaire et d'extension infinie représentant un défaut volumique simple. Le champ diffuse par le cylindre et transmis a l'intérieur du cylindre constitue soit d'un milieu fluide, soit du vide, soit d'un solide élastique ou d'un solide rigide a été étudie dans le cas ou le cylindre est contenu soit dans un fluide, soit dans un solide élastique. La diffusion a été décrite par une série de modes de vibration normaux. Il a alors fallu déterminer dans chaque cas traite le nombre de modes à conserver dans la série, ce qui est résolu par un test de convergence. Des signaux numériques ont été compares avec des signaux expérimentaux dans le cas ou le milieu de propagation est de l'aluminium ou de l'acier, et le cylindre est soit le vide, soit de l'alumine ou de la silice. Un très bon accord permet ainsi la validation du logiciel.
Download or read book Mod lisation des m canismes de r trodiffusion du signal ultrasonore par le sang written by Isabelle Fontaine and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mod lisation des m canismes de r trodiffusion du signal ultrasonore par le sang written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mod lisation des m canismes de r trodiffusion du signal ultrasonore par le sang microforme written by Isabelle Fontaine and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 1999 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Apport du traitement du signal la mod lisation d un syst me d imagerie ultrasonore written by Marc Bernard and published by . This book was released on 1985 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Delamination in Wood Wood Products and Wood Based Composites written by Voichita Bucur and published by Springer Science & Business Media. This book was released on 2010-11-02 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last quarter century, delamination has come to mean more than just a failure in adhesion between layers of bonded composite plies that might affect their load-bearing capacity. Ever-increasing computer power has meant that we can now detect and analyze delamination between, for example, cell walls in solid wood. This fast-moving and critically important field of study is covered in a book that provides everyone from manufacturers to research scientists the state of the art in wood delamination studies. Divided into three sections, the book first details the general aspects of the subject, from basic information including terminology, to the theoretical basis for the evaluation of delamination. A settled terminology in this subject area is a first key goal of the book, as the terms which describe delamination in wood and wood-based composites are numerous and often confusing. The second section examines different and highly specialized methods for delamination detection such as confocal laser scanning microscopy, light microscopy, scanning electron microscopy and ultrasonics. Ways in which NDE (non-destructive evaluation) can be employed to detect and locate defects are also covered. The book’s final section focuses on the practical aspects of this defect in a wide range of wood products covering the spectrum from trees, logs, laminated panels and glued laminated timbers to parquet floors. Intended as a primary reference, this book covers everything from the microscopic, anatomical level of delamination within solid wood sections to an examination of the interface of wood and its surface coatings. It provides readers with the perspective of industry as well as laboratory and is thus a highly practical sourcebook for wood engineers working in manufacturing as well as a comprehensively referenced text for materials scientists wrestling with the theory underlying the subject.
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 An Introduction to Mathematics of Emerging Biomedical Imaging written by Habib Ammari and published by Springer Science & Business Media. This book was released on 2008-05-21 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomedical imaging is a fascinating research area to applied mathematicians. Challenging imaging problems arise and they often trigger the investigation of fundamental problems in various branches of mathematics. This is the first book to highlight the most recent mathematical developments in emerging biomedical imaging techniques. The main focus is on emerging multi-physics and multi-scales imaging approaches. For such promising techniques, it provides the basic mathematical concepts and tools for image reconstruction. Further improvements in these exciting imaging techniques require continued research in the mathematical sciences, a field that has contributed greatly to biomedical imaging and will continue to do so. The volume is suitable for a graduate-level course in applied mathematics and helps prepare the reader for a deeper understanding of research areas in biomedical imaging.
Download or read book Physics for Medical Imaging Applications written by Yves Lemoigne and published by Springer Science & Business Media. This book was released on 2007-01-05 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the fundamental aspects of digital imaging and covers four main themes: ultrasound techniques and imaging applications, magnetic resonance and MPJ in hospital, digital imaging with X-rays, and emission tomography (PET and SPECT). Each topic is developed by analyzing the underlying physics principles and their implementation, quality and safety aspects, clinical performance, and recent advancements in the field.
Download or read book Mechanical Identification of Composites written by A. Vautrin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applications of X ray Computed Tomography in the Geosciences written by Florias Mees and published by Geological Society of London. This book was released on 2003 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: X-ray computed tomography (CT) is a technique that allows non-destructive imaging and quantification of internal features of objects. X-ray CT reveals differences in density and atomic composition and can therefore be used for the study of porosity, the relative distribution of contrasting solid phases and the penetration of injected solutions. In this book, various applications of X-ray CT in the geosciences are illustrated by papers covering a wide range of disciplines, including petrology, soil science, petroleum geology, geomechanics and sedimentology.
Download or read book 5th International Conference on Biomedical Engineering in Vietnam written by Vo Van Toi and published by Springer. This book was released on 2014-11-18 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the proceedings of the Fifth International Conference on the Development of Biomedical Engineering in Vietnam which was held from June 16-18, 2014 in Ho Chi Minh City. The volume reflects the progress of Biomedical Engineering and discusses problems and solutions. I aims identifying new challenges, and shaping future directions for research in biomedical engineering fields including medical instrumentation, bioinformatics, biomechanics, medical imaging, drug delivery therapy, regenerative medicine and entrepreneurship in medical devices.
Download or read book Food Engineering Integrated Approaches written by Gustavo F. Gutiérrez-Lopez and published by Springer Science & Business Media. This book was released on 2008-02-29 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a significant and up-to-date review of various integrated approaches to food engineering. Distinguished food engineers and food scientists from key institutions worldwide have contributed chapters that provide a deep analysis of their particular subjects. Emerging technologies and biotechnology are introduced, and the book discusses predictive microbiology, packing materials for foods, and biodegradable films. This book is mainly directed to academics, and to undergraduate and postgraduate students in food engineering and food science and technology, who will find a selection of topics.
Download or read book Mechcomp2 written by Antonio J.M. Ferreira and published by Società Editrice Esculapio. This book was released on 2016-05-20 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composites materials have aroused a great interest over the last few decades. Several applications of fibrous composites, functionally graded materials, laminated composites, nano-structured reinforcements, morphing structures, can be found in many engineering fields, such as aerospace, mechanical, naval and civil engineering. The necessity of lightweight structures, smart and adaptive systems, high-level strength, have led both the academic research and the manufacturing development to a recurring employment of these materials. Many journal papers and technical notes have been published extensively over the last seventy years in international scientific journals of different engineering fields. For this reason, the establishment of this second edition of Mechanics of Composites International Conference has appeared appropriate to continue what has been begun during the first edition occurred in 2014 at Stony Brook University (USA). MECHCOMP wants to be an occasion for many researchers from each part of the globe to meet and discuss about the recent advancements regarding the use of composite structures. As a proof of this event, which has taken place in Porto (Portugal), selected plenary and key-note lectures have been collected in the present book.
Download or read book Biomedical Images and Computers written by J. Sklansky and published by Springer. This book was released on 2014-03-12 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: The technology of automatic pattern recognition and digital image processing, after over two decades of basic research, is now appearing in important applications in biology and medicine as weIl as industrial, military and aerospace systems. In response to a suggestion from Mr. Norman Caplan, ·the Program Director for Automation, Bioengineering and Sensing at the United States National Science Foundation, the authors of this book organized the first Uni ted States-France Seminar on Biomedical Image Processing. The seminar met at the Hotel Beau Site, St. Pierre de Chartreuse, France on May 27-31, 1980. This book contains most of the papers presented at this seminar, as weIl as two papers (by Bisconte et al. and by Ploem ~ al.) discussed at the seminar but not appearing on the program. We view the subject matter of this seminar as a confluence amon~ three broad scientific and engineering disciplines: 1) biology and medicine, 2) imaging and optics, and 3) computer science and computer engineering. The seminar had three objectives: 1) to discuss the state of the art of biomedical image processing with emphasis on four themes: microscopic image analysis, radiological image analysis, tomography, and image processing technology; 2) to place values on directions for future research so as to give guidance to agencies supporting such research; and 3) to explore and encourage various areas of cooperative research between French and Uni ted States scientists within the field of Biomedical Image Processing.
