Download or read book RECONNAISSANCE DE CIBLES PAR SONAR ACTIF APPLICATION A DES COQUES DE FORME SIMPLE ET A LA CLASSIFICATION DES ESPECES DE POISSONS EN MER written by FRANCOIS.. MAGAND and published by . This book was released on 1996 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE ETUDE PRESENTE UNE METHODE DE CLASSIFICATION DE CIBLES SONAR QUI S'APPUIE SUR LA MODELISATION DES PHENOMENES PHYSIQUES MIS EN JEU DANS LA DIFFUSION D'UNE ONDE ACOUSTIQUE PAR UNE COQUE DE FORME SIMPLE (SPHERE, CYLINDRE). LE PROCEDE DE RECONNAISSANCE COMPORTE DEUX ETAPES. DANS UN PREMIER TEMPS, ON REALISE LA DISCRIMINATION ENTRE L'ECHO D'UNE COQUE ET CELUI D'UNE CIBLE NATURELLE, ASSIMILEE A UNE CIBLE PLEINE. LA SECONDE ETAPE CONSISTE A ESTIMER LES CARACTERISTIQUES GEOMETRIQUES (RAYON EXTERNE, EPAISSEUR) ET MECANIQUES (CELERITE TRANSVERSALE, DENSITE) DE LA COQUE QUE L'ON SUPPOSE MINCE. DEUX METHODES DE CLASSIFICATION SONT COMPAREES: UNE APPROCHE BAYESIENNE ET UNE APPROCHE CONNEXIONNISTE. LES PARAMETRES CLASSIFIANT SONT EXTRAITS DE LA SIGNATURE SPECTRALE DES CIBLES AU MOYEN D'UN MODELE PARAMETRIQUE (MODELISATION AUTOREGRESSIVE) AINSI QU'AU MOYEN D'UN MODELE DE DIFFUSION (POINTS BRILLANTS COLORES). LES RESULTATS OBTENUS MONTRENT LA FAISABILITE DE LA DISCRIMINATION, MEME EN PRESENCE DE BRUIT OU D'EFFET DOPPLER. L'ESTIMATION DES CARACTERISTIQUES DE LA CIBLE REPOSE SUR UNE ANALYSE APPROFONDIE DE LA STRUCTURE TEMPS-FREQUENCE DES ECHOS DE COQUES SPHERIQUES MINCES, QUI MONTRE QUE LA CONTRIBUTION ENERGETIQUE PRINCIPALE PROVIENT DE L'INTERACTION CONSTRUCTIVE ENTRE DEUX ONDES DE SURFACE. L'ESTIMATION DU RAYON EXTERNE S'EFFECTUE EN COMPARANT LE SIGNAL INCONNU A L'ECHO DILATE OU COMPRIME D'UNE CIBLE DE REFERENCE. CELLE DES AUTRES PARAMETRES S'OBTIENT EN INVERSANT LA RELATION NON-LINEAIRE QUI LIE CES PARAMETRES A LA FORME DU MOTIF D'INTERACTION DANS LE PLAN TEMPS-FREQUENCE AU MOYEN D'UN RESEAU DE NEURONES MULTICOUCHE. LA METHODE DE RECONNAISSANCE, TESTEE AVEC SUCCES SUR DES DONNEES EXPERIMENTALES, S'AVERE PARTICULIEREMENT ROBUSTE EN PRESENCE DE BRUIT. L'APPLICATION DE LA CLASSIFICATION A UN CAS REEL S'INSCRIT DANS LE CONTEXTE DE L'ACOUSTIQUE DE PECHE (RECONNAISSANCE DES ESPECES DES POISSONS PAR LEUR SIGNATURE ACOUSTIQUE). LES DONNEES ONT ETE OBTENUES A PARTIR DE MESURES EN LAC SUR DES POISSONS EN CAGE AINSI QU'A PARTIR D'ESSAIS EN MER. DANS LE CAS DES POISSONS EN CAGE, ON MONTRE QUE LA SIGNATURE SPECTRALE DES ECHOS EST CORRELEE A L'ESPECE, INDEPENDAMMENT DU NOMBRE D'INDIVIDUS OU DE LEUR TAILLE. LES DONNEES ISSUES DES ESSAIS EN MER PERMETTENT QUANT A ELLES DE MONTRER LA FAISABILITE DE LA DISCRIMINATION DES ESPECES

Download or read book Theoretical And Computational Acoustics 97 written by Er-chang Shang and published by World Scientific. This book was released on 1999-05-11 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is dedicated to Dr Ding Lee for his untiring efforts in promoting the advancement of theoretical and computational acoustics.This proceedings volume provides a forum for active researchers to discuss the state-of-the-art developments and results in theoretical and computational acoustics, covering aero-, seismo- and ocean acoustics and related topics. It discusses multidimensional wave propagation modeling, methods of computational acoustics, wave propagation in rocks, fluid-solid interfaces, nonlinear acoustics, neural networks, real applications and experimental results.

Download or read book Proceedings of the 1998 IEEE International Conference on Acoustics Speech and Signal Processing written by and published by . This book was released on 1998 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Contribution la caract risation et l identification de formes simples par sonar actif written by Manell E.. Zakharia and published by . This book was released on 1982 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: PERCEPTION ACOUSTIQUE D'UN MILIEU PAR SONAR ACTIF. MODELISATION DE LA CIBLE. METHODES D'ANALYSE ET DE CLASSIFICATION DES CIBLES. APPLICATION A L'ETUDE ET LA REALISATION D'UN SONAR DE PECHE

Download or read book La classification de cibles aquatiques par sonar large bande written by Cecile Chorier and published by . This book was released on 1996 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: EN RECONNAISSANCE DES ESPECES DE POISSONS PAR SONAR LARGE BANDE, L'ETUDE EST CONSACREE AUX POISSONS ISOLES, NAGEANT LIBREMENT EN CUVE. LA CLASSIFICATION SE DECOMPOSE EN TROIS ETAPES: L'ACQUISITION DE DONNEES, L'EXTRACTION DE PARAMETRES PERTINENTS PUIS LA DECISION. C'EST POURQUOI, LE TRAVAIL A D'ABORD CONSISTE A METTRE EN UVRE UN SYSTEME SONAR ADAPTE: LARGE BANDE (20-140 KHZ). POUR MAINTENIR LE POISSON DANS LE FAISCEAU ACOUSTIQUE, UNE CAGE EST CONSTRUITE. UNE ETUDE BIBLIOGRAPHIQUE ET EXPERIMENTALE A PERMIS DE COMPARER PREALABLEMENT DIFFERENTS MATERIAUX: LE FILET A FOURNI LA REPONSE LA PLUS FAIBLE. LA BASE DE DONNEES EST COMPOSEE DE 1950 ECHOS, ASSOCIES A 39 POISSONS, REPARTIS EN TROIS ESPECES DE POISSONS (PERCHE, GARDON ET OMBLE). SOIT 50 ECHOS POUR CHAQUE POISSON, CHAQUE ECHO CORRESPONDANT A UNE POSITION DIFFERENTE. ENSUITE, UNE ETUDE PRELIMINAIRE SUR LES PRETRAITEMENTS A PERMIS D'EN RETENIR QUATRE: LES MOYENNES SUR DES BANDES DE FREQUENCE DE LARGEUR CONSTANTE, LES MOYENNES SUR DES BANDES DE FREQUENCE D'AIRES CONSTANTES DU SPECTRE MOYEN, DES COEFFICIENTS DE LA MODELISATION AR ET DES COEFFICIENTS DE LA MODELISATION ARMA. L'ETAPE DE DECISION EST REALISEE PAR UN RESEAU DE NEURONES PARTICULIER: LE RESEAU PERCEPTRON MULTICOUCHE ENTRAINE PAR L'ALGORITHME DE RETROPROPAGATION DU GRADIENT. EN CONCLUSION, LE TAUX DE RECONNAISSANCE INTERSPECIFIQUE ATTEINT 80% AVEC UNE CLASSIFICATION HIERARCHIQUE NEURONALE. LES RESULTATS, OBTENUS SUR DES POISSONS DE TAILLES DIFFERENTES, MONTRENT QUE LA RECONNAISSANCE DES ESPECES PAR ECHO SONAR LARGE BANDE EST POSSIBLE

Download or read book Regional Conference on building a future for sustainable small scale fisheries in the Mediterranean and the Black Sea written by Food and Agriculture Organization of the United Nations and published by Food & Agriculture Org.. This book was released on 2018-10-31 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: According to the report, the conference focused on the main challenges for the sustainable development of small-scale fisheries, including promoting political commitment and tailored strategies, raising awareness, and sharing knowledge.

Download or read book The Athenian Trireme written by J. S. Morrison and published by Cambridge University Press. This book was released on 2000-07-20 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Second edition of the technical and historical background to the reconstruction of a Greek warship.

Download or read book Audio Effectiveness in Aviation written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Aerospace Medical Panel. Symposium and published by . This book was released on 1997 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ships of the Pharaohs written by Björn Landström and published by . This book was released on 1970 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Classical Marble Geochemistry Technology Trade written by N. Herz and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marble in Ancient Greece and Rome: Geology, Quarries, Commerce, Artifacts Marble remains the sine qua non raw material of the an cient Greeks and Romans. Beginning in the Bronze Age sculptu re began in marble and throughout classical times the most im portant statues, reliefs, monuments and inscriptions were made of it. Yet, quarry sources changed in time as preferences for different marbles were influenced by local traditions, the pos sibilities of transport, esthetic tastes, and economics. Marble studies and the identification of the provenance of marble can thus reveal much about Greek and Roman history, trade, esthe tics and technology. Persons in many disciplines are studying various aspects of Greek and Roman marble usage. Geologists and geochemists are working on methods to determine the provenance of marble; ar chaeologists are noting changing patterns of import and use in excavation~ and discovering how improving quarrying techniques and prelimihary dressing of the extracted material influenced the final shape of artifacts; ancient historians are now under standing quarry organization and bureaucracies that controlled marble production and trade; art historians are seeing how phy sical characteristics of the stone affected the techniques and style of sculpture; architects and engineers are interested in quarry technologies and usage in building construction. These specialists drawn from many disciplines rarely have an opportu nity to compare notes and see how each can contribute to the research effort of others.

Download or read book Ancient Greece written by and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Great Inventions written by Richard Wood and published by . This book was released on 2003 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Yassi Ada written by George Fletcher Bass and published by Texas A&M University Press. This book was released on 1982 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book forms a final report on the underwater excavations I directed at Yassi Ada, Turkey, during the summers of 1961 through 1964 for the University Museum of the University of Pennsylvania. The excavation was the first to have been completed on the floor of the Mediterranean of a wreck with substantial hull remains. This pioneering work required the ingenuity, effort, and generosity of many people and institutions. The seventh- century ship was chosen for primary excavation not only for its lesser depth, which allowed longer working dives, but also because Throckmorton had uncovered traces of its timbers just beneath the sand and because it was more intelligible from the outset: a stack of concreted iron anchors, lying across the cargo at its upper end, suggested the forward part of the ship pointing up the slope, toward Yassi Ada, while a mass of broken terra-cotta tiles and cooking ware suggested the galley--and, presumably, the stern--at the deeper end of the site.

Download or read book Marine Archaeology written by Elisha Linder and published by Weidenfeld & Nicolson. This book was released on 1975 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: