Download or read book ANALYSE TEMPS FREQUENCE DE SIGNAUX SONAR TRES LARGE BANDE written by NING.. MA and published by . This book was released on 1996 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: CE TRAVAIL CONCERNE LA CARACTERISATION DU FOND MARIN AU MOYEN D'UN SONAR TRES LARGE BANDE A DIRECTIVITE CONSTANTE. L'ORIGINALITE DE L'ETUDE REPOSE D'UNE PART SUR LA MISE EN UVRE D'UN SYSTEME SONAR EXPERIMENTAL CAPABLE D'EMETTRE ET DE RECEVOIR DES SIGNAUX CHIRP (MODULATION LINEAIRE DE FREQUENCE ENTRE 20-140 KHZ) ET D'AUTRE PART SUR LE DEVELOPPEMENT DE METHODES DE MODELISATION, D'IDENTIFICATION ET DE CLASSIFICATION ADAPTEES A L'ANALYSE DES SIGNAUX RETRODIFFUSES PAR LE FOND MARIN. DANS UNE PREMIERE PARTIE, LES SIGNAUX COLLECTES SUR 5 TYPES DE FONDS DIFFERENTS SONT ANALYSES PAR LA FONCTION D'AMBIGUITE POUR LAQUELLE ON COMPARE LES PERFORMANCES DES FORMULATIONS LARGE BANDE ET BANDE ETROITE AINSI QUE LES RELATIONS EXISTANT AVEC LES REPRESENTATIONS TEMPS-FREQUENCE. DANS UNE DEUXIEME PARTIE, LA REPARTITION DE L'ENERGIE RETRODIFFUSEE PAR LE FOND EST ANALYSEE DANS LE PLAN TEMPS-FREQUENCE CE QUI PERMET DE RENDRE COMPTE DES PHENOMENES DE DIFFUSION DE L'ONDE ACOUSTIQUE D'UN POINT DE VUE SPATIAL ET FREQUENTIEL. AFIN D'AMELIORER LA LISIBILITE DES REPRESENTATIONS TEMPS-FREQUENCE DE TYPE WIGNER-VILLE, NOUS AVONS PROPOSE UNE REPRESENTATION ORIGINALE ADAPTEE AUX SIGNAUX CHIRP ET LA COMPARAISON AVEC LES AUTRES REPRESENTATIONS DE LA CLASSE DE COHEN MONTRE L'AMELIORATION APPORTEE PAR NOTRE METHODE. ENFIN, DANS UNE 3EME PARTIE, UN MODELE DE RETRODIFFUSION PAR UNE SURFACE RUGUEUSE EST DEVELOPPE. NOUS MONTRONS QUE CE MODELE EST LA CONVOLUTION ENTRE LA REPONSE IMPULSIONNELLE D'UN FOND PLAN ET LA DENSITE DE PROBABILITE DES RUGOSITES. UNE PROCEDURE D'ESTIMATION DE LA RUGOSITE A PARTIR DES DONNEES EXPERIMENTALES EST PROPOSEE. CE MODELE EST BIEN ADAPTE AUX FONDS DE SABLE, GRAVIERS ET GALETS ALORS QUE LE FOND DE VASE NECESSITE UN MODELE PRENANT EN COMPTE LA PROPAGATION DE L'ONDE ACOUSTIQUE DANS LA COUCHE SEDIMENTAIRE. DANS CHAQUE SITUATION, LES RESULTATS DES ANALYSES DES SIGNAUX SONT CONFRONTES AUX ANALYSES GEOTECHNIQUES REALISEES DURANT L'ETUDE
Download or read book Analyse et mod lisation de signaux sonores par des repr sentations temps fr quence lin aires written by Philippe Guillemain and published by . This book was released on 1994 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE THESE CONCERNE L'ANALYSE ET LA MODELISATION DE SIGNAUX SONORES. LES TECHNIQUES DEVELOPPEES FONT APPEL A DES REPRESENTATIONS TEMPS-ECHELLE ET TEMPS-FREQUENCE LINEAIRES ET CONTINUES, TELLES QUE LA TRANSFORMEE EN ONDELETTES ET LA TRANSFORMEE DE GABOR. A PARTIR DE L'ETUDE THEORIQUE DU COMPORTEMENT DES TRANSFORMEES DE SIGNAUX DETERMINISTES APPARTENANT A DES CLASSES SPECIFIQUES, TELS QUE LES SIGNAUX ASYMPTOTIQUES ET LES SIGNAUX TRANSITOIRES, ON DEVELOPPE UN ENSEMBLE DE TECHNIQUES CONDUISANT A L'ESTIMATION DE PARAMETRES QUANTITATIFS CARACTERISANT LE SIGNAL. DANS UNE OPTIQUE D'ANALYSE-SYNTHESE DE SONS PRODUITS PAR DES INSTRUMENTS DE MUSIQUE TRADITIONNELS, ON CONSIDERE TOUT D'ABORD LE CAS DE SIGNAUX NON STATIONNAIRES COMPOSES DE SOMMES DE CONTRIBUTIONS ELEMENTAIRES MODULEES EN AMPLITUDE ET EN FREQUENCE AU COURS DU TEMPS. A PARTIR DE DEVELOPPEMENTS EN SERIE ET D'APPROXIMATIONS ASYMPTOTIQUES DE LEURS TRANSFORMEES, ON PROPOSE DES ALGORITHMES PERMETTANT D'ISOLER CHAQUE COMPOSANTE ET D'ESTIMER SON AMPLITUDE ET SA FREQUENCE INSTANTANEES, SANS HYPOTHESE A PRIORI SUR LA SELECTIVITE TEMPORELLE ET FREQUENTIELLE DE L'ANALYSE. UNE MODELISATION DE CE TYPE CONDUIT NATURELLEMENT A UNE RESYNTHESE DITE ADDITIVE, QUI PEUT EGALEMENT DONNER LIEU A DES TRANSFORMATIONS MUSICALES INTIMES PAR SIMPLE MODIFICATION DES PARAMETRES ESTIMES. ON S'INTERESSE ENSUITE A LA CARACTERISATION DE SIGNAUX TRANSITOIRES. POUR CELA, ON CHOISIT TOUT D'ABORD LA CLASSE DES FONCTIONS HOMOGENES DE DEGRE COMPLEXE COMME MODELE DE SIGNAL, QUI DONNE LIEU A UNE TRANSFORMEE EN ONDELLETTES EXPLICITE DONT ON EXPLOITE LES PROPRIETES AFIN D'ESTIMER LE DEGRE D'HOMOGENEITE. LES RESULTATS OBTENUS SONT ETENDUS AU CAS DE SIGNAUX LARGE BANDE, POUR LESQUELS ON PROPOSE DES ALGORITHMES PERMETTANT D'ESTIMER LA DENSITE SPECTRALE ET LE RETARD DE GROUPE. CETTE ETUDE A PERMIS EN PARTICULIER DE METTRE EN PARALLELE LE COMPORTEMENT DES TRANSFORMEES DE SIGNAUX LOCALISES SOIT SPECTRALEMENT, SOIT TEMPORELLEMENT
Download or read book METHODES ACTIVES SPATIO TEMPORELLES LARGE BANDE TECHNIQUES ET PERFORMANCES APPLICATION A DES SIGNAUX SONAR ET A DES SIGNAUX OBTENUS EN TRANSMISSION written by PHILIPPE.. GRAFFOULIERE and published by . This book was released on 1997 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: METHODES ACTIVES SPATIO-TEMPORELLES LARGE BANDE : TECHNIQUES ET PERFORMANCES. APPLICATION EN SONAR. CERTAINS PROCEDES D'ESTIMATION ET DE DETECTION SONT DITS ACTIFS, LORSQUE LA PREMIERE ETAPE CONSISTE EN L'EMISSION D'UN SIGNAL CONNU. NOUS NOUS SOMMES INTERESSES AUX METHODES DE TRAITEMENT DES SIGNAUX ISSUS DE CE TYPE D'EXPERIMENTATION, COMME LES SIGNAUX DE SONAR ACTIF OU DE TOMOGRAPHIE OCEANIQUE, EN S'APPUYANT SYSTEMATIQUEMENT SUR UNE HYPOTHESE DE BANDE LARGE. LA PREMIERE PARTIE EST CONSACREE AU TRAITEMENT D'ANTENNE ACTIF, ON Y RAPPELLE LES ESTIMATEURS OPTIMAUX, LES BORNES DE CRAMER-RAO ASSOCIEES, DANS DIVERSES CONFIGURATIONS D'ANTENNE ET DE SIGNAUX. LE TRAITEMENT OPTIMAL Y EST COMPARE A UNE METHODE RAPIDE INTERFEROMETRIQUE. LA DEUXIEME PARTIE EST CONSACREE A L'ESTIMATION RETARD DOPPLER, ON Y RAPPELLE LES ESTIMATEURS OPTIMAUX, LES BORNES DE CRAMER-RAO ASSOCIEES, EN INSISTANT SUR LES NOTIONS DE DECOUPLAGE DES ESTIMATEURS. LES RESULTATS SONT DISCUTES EN FONCTION DU DECOUPLAGE, DEPENDANT DE LA NATURE DES SIGNAUX. LA TROISIEME PARTIE EST CONSACREE A L'ESTIMATION ACTIVE SPATIO-TEMPORELLE HAUTE RESOLUTION. L'UTILISATION DE METHODES DE MAXIMUM DE VRAISEMBLANCE DANS CE BUT A ETE MONTREE POSSIBLE, MOYENNANT QUELQUES AMELIORATIONS APPORTEES. UNE EXTENSION A L'ESTIMATION HR RETARD-DOPPLER EST RAPIDEMENT DEVELOPPEE. LA QUATRIEME PARTIE EST CONSACREE A L'EVALUATION DE LA PERTE DE PERFORMANCES QUAND CES METHODES NE SONT PLUS OPTIMALES : SI LE BRUIT EST COLORE, L'ANTENNE DEFORMEE, LE SIGNAL EMIS DISTORDU... LA METHODE UTILISEE POUR CE FAIRE EST LE CALCUL DE PERTURBATIONS. DE NOMBREUSES SIMULATIONS CORROBORENT LES RESULTATS. ENFIN, LES METHODES HR SONT TESTEES AU MOYEN DE DEUX EXPERIMENTATIONS. LES RESULTATS OBTENUS SONT SATISFAISANTS, ET MONTRENT LA POSSIBILITE D'APPLIQUER CES METHODES AVEC SUCCES.
Download or read book METHODES EXPERIMENTALES DE DETECTION ET D IDENTIFICATION DE SIGNAUX ACOUSTIQUES A BANDE ETROITE BASEES SUR UNE INTERPRETATION DES FREQUENCES INSTANTANEES written by CHRISTINE.. BERNERDINI and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: L'OBJET DU TRAVAIL PRESENTE DANS CETTE THESE, EST UNE CONTRIBUTION A L'ANALYSE EXPERIMENTALE DES EMISSIONS SONAR DANS LE BUT D'UNE IDENTIFICATION DE CELLES-CI. APRES AVOIR PRESENTE UN BREF APERCU DES TECHNIQUES ET MOYENS LE PLUS SOUVENT UTILISES DANS LES LABORATOIRES D'ESSAIS, NOUS EFFECTUONS UNE ETUDE TEMPORELLE PAR LA DESCRIPTION DE L'ENVELOPPE DES DIVERS SIGNAUX TRANSITOIRES. CETTE ETUDE EXPERIMENTALE APPORTE CERTES DES INFORMATIONS, NOTAMMENT SUR LA DUREE DES TRANSITOIRES, MAIS LARGEMENT INSUFFISANTE POUR REPONDRE A NOTRE SOUHAIT DE CLASSIFICATION. L'ETUDE FREQUENTIELLE, BASEE SUR LA LOCALISATION ET L'INTERPRETATION DES DATES POUR LESQUELLES LE SIGNAL CENTRE EST NUL, TENTE DE METTRE EN EVIDENCE LES FLUCTUATIONS DE FREQUENCES INSTANTANEES. NOUS DONNONS UNE INTERPRETATION QUANTITATIVE DE CES FLUCTUATIONS AU MOYEN D'UN MODELE SIMPLIFIE DE LA DENSITE SPECTRALE DE PUISSANCE DES EMISSIONS SONAR, QUI DANS LE PLUS GRAND NOMBRE DE SITUATIONS, PERMET UNE IDENTIFICATION DES SIGNAUX EXPERTISES AU PREALABLE. LES MODULATIONS DE PHASE OU DE FREQUENCE MISES EN EVIDENCE SUR DES SIGNAUX REPUTES DE FREQUENCE PURE, LAISSENT PENSER QU'ELLES DEVRAIENT SE TRADUIRE PAR LA PRESENCE DE RAIES SPECTRALES SYMETRIQUES PAR RAPPORT A LA FREQUENCE CENTRALE DE L'EMISSION. LA MISE EN EVIDENCE D'AUTRES RAIES NECESSITE DONC UNE PROCEDURE DE BLANCHIMENT. NOUS PRESENTONS LA METHODE DE BLANCHIMENT ET LES CONSIDERATIONS QUI NOUS CONDUISENT A JUSTIFIER DE SON EMPLOI. LES ANALYSES REALISEES MONTRENT QUE DANS TOUS LES CAS, DE NOMBREUSES RAIES PEUVENT ETRE LOCALISEES. NOUS PENSONS QUE LA DISTRIBUTION DES FREQUENCES DE CES RAIES PEUT LARGEMENT PARTICIPER A L'IDENTIFICATION DES SOURCES SONORES
Download or read book Wavelets written by Jean-Michel Combes and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last two subjects mentioned in the title "Wavelets, Time Frequency Methods and Phase Space" are so well established that they do not need any explanations. The first is related to them, but a short introduction is appropriate since the concept of wavelets emerged fairly recently. Roughly speaking, a wavelet decomposition is an expansion of an arbitrary function into smooth localized contributions labeled by a scale and a position pa rameter. Many of the ideas and techniques related to such expansions have existed for a long time and are widely used in mathematical analysis, theoretical physics and engineering. However, the rate of progress increased significantly when it was realized that these ideas could give rise to straightforward calculational methods applicable to different fields. The interdisciplinary structure (R.C.P. "Ondelettes") of the C.N.R.S. and help from the Societe Nationale Elf-Aquitaine greatly fostered these developments. The conference, the proceedings of which are contained in this volume, was held at the Centre National de Rencontres Mathematiques (C.N.R.M) in Marseille from December 14-18, 1987 and bought together an interdisciplinary mix of par ticipants. We hope that these proceedings will convey to the reader some of the excitement and flavor of the meeting.
Download or read book Modelling the Wireless Propagation Channel written by Fernando P¿rez Font¿n and published by John Wiley & Sons. This book was released on 2008-09-15 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical tool for propagation channel modeling with MATLAB® simulations. Many books on wireless propagation channel provide a highly theoretical coverage, which for some interested readers, may be difficult to follow. This book takes a very practical approach by introducing the theory in each chapter first, and then carrying out simulations showing how exactly put the theory into practice. The resulting plots are analyzed and commented for clarity, and conclusions are drawn and explained from the obtained results. Key features include: A unique approach to propagation channel modeling with accompanying MATLAB® simulations to demonstrate the theory in practice Contains step by step commentary and analysis of the obtained simulation results in order to provide a comprehensive and structured learning tool Covers a wide range of topics including shadowing effects, coverage and interference, Multipath Narrowband channel, Multipath Wideband channel, propagation in micro and pico-cells, the land mobile satellite (LMS) channel, the directional Multipath channel and MIMO and propagation effects in fixed radio links (terrestrial and satellite) The book comes with an accompanying website that contains the MATLAB® simulations and allows readers to try them out themselves Well suited for lab-use, as reference and as a self-learning tool both for advanced students and professionals Modeling the Wireless Propagation Channel: A simulation approach with MATLAB® will be best suited for postgraduate (Masters and PhD) students and practicing engineers in telecommunications and electrical engineering fields, who are seeking to familiarise themselves with the topic without too many formulas. The book will also be of interest to network engineers, system engineers and researchers
Download or read book Catalogue of Marine Instrumentation written by M. Weydert and published by . This book was released on 1991 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colloque de Physique written by and published by . This book was released on 1990 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transforms and Applications Handbook written by Alexander D. Poularikas and published by CRC Press. This book was released on 2018-09-03 with total page 911 pages. Available in PDF, EPUB and Kindle. Book excerpt: Updating the original, Transforms and Applications Handbook, Third Edition solidifies its place as the complete resource on those mathematical transforms most frequently used by engineers, scientists, and mathematicians. Highlighting the use of transforms and their properties, this latest edition of the bestseller begins with a solid introduction to signals and systems, including properties of the delta function and some classical orthogonal functions. It then goes on to detail different transforms, including lapped, Mellin, wavelet, and Hartley varieties. Written by top experts, each chapter provides numerous examples and applications that clearly demonstrate the unique purpose and properties of each type. The material is presented in a way that makes it easy for readers from different backgrounds to familiarize themselves with the wide range of transform applications. Revisiting transforms previously covered, this book adds information on other important ones, including: Finite Hankel, Legendre, Jacobi, Gengenbauer, Laguerre, and Hermite Fraction Fourier Zak Continuous and discrete Chirp-Fourier Multidimensional discrete unitary Hilbert-Huang Most comparable books cover only a few of the transforms addressed here, making this text by far the most useful for anyone involved in signal processing—including electrical and communication engineers, mathematicians, and any other scientist working in this field.
Download or read book Ambient Noise in the Sea written by Robert J. Urick and published by . This book was released on 1984 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 2020 17th European Radar Conference EuRAD written by IEEE Staff and published by . This book was released on 2021-01-10 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: radar
Download or read book First French Conference on Acoustics written by Paul Filippi and published by . This book was released on 1990 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geology and Natural Hazards of the Fraser River Delta British Columbia written by John Joseph Clague and published by . This book was released on 1998 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 16 papers in this volume constitute a summary of recent research on the geological architecture and environment of the Fraser River delta, and the physical and chemical processes operating on it. The first two papers are overviews of the geological and seismic setting of the delta. The next two papers summarize present-day sedimentary environments on the delta. A third group of papers covers the geological architecture, or lithostratigraphy, of the delta and the biological structure or biofacies of the delta. The final group of papers is concerned with natural hazards and environmental issues, including earthquakes, geotechnical stability, and seafloor sediment geochemistry.
Download or read book Telecommunication Journal written by and published by . This book was released on 1989 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Limitations Neurologiques Des Op rations A riennes 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 1996 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 2nd Pan African Symposium on the Sustainable Use of Natural Resources in Africa written by Bihini won wa Musiti and published by IUCN. This book was released on 2003 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: This bilingual publication results from a four-day symposium aimed at capturing the general directions and analytical issues that characterize approaches to sustainable use in Africa. The papers included in this work are organized under four major headings: modes of use, devolution, scale issues and external issues. Authors explore these themes through the use of case studies and the description of specific regional experiences. External issues are further explored in a series of commissioned policy papers which have also been included.
