A time-frequency approach to blind deconvolution in multipath underwater channels

Blind deconvolution is presented in the underwater acoustic channel context, by time-frequency processing. The acoustic propagation environment was modelled as a multipath propagation channel. For noiseless simulated data, source signature estimation was performed by a model-based method. The channel estimate was obtained via a time-frequency formulation of the conventional matched-filter. Simulations used a ray-tracing physical model, initiated with at-sea recorded environmental data, in order to produce realistic underwater channel conditions. The quality of the estimates was 0.793 for the source signal, and close to I for the resolved amplitudes and time-delays of the impulse response. Time-frequency processing has proved to overcome the typical ill-conditioning of single sensor deterministic deconvolution techniques

Optimal design of a whale of anti-collision system

This paper summerizes tools coming from estimation’s theory to evaluate and design experimental device. Theses tools are applied to the "Whale Anti Collision System" dedicated to localise Sperm Whales and to avoid collision with ships. Relying on theoretical tools, our approach tries to be as close as possible of reality by using true sperm clicks, realistic measurement noise by allowing sensors and acoustic environmental missknowledges. Without any acoustic environmental assesment, WACS system shows to be a good tool for biology study but may not be enougth accurate to be included in a anti-collision network. With an acoustic environmental assesment, WACS system is accurate enough to be included in an anti-collision network. WACS settings and step of the anti-collision network are identified.Dans cet article, des outils issus de la théorie de l’estimation sont proposés pour permettre l’évaluation des performances et le dimensionnement de systèmes expérimentaux. Ceux-ci ont été appliqués au système WACS (Whales Anti Collision System), système de localisation passive des cachalots vocalisants ou non afin de contribuer à réduire les collisions avec les navires. Basée sur des outils théoriques, l’approche proposée s’attache à se rapprocher au mieux de la réalité par les hypothèses effectuées. Sans monitorage de l’environnement acoustique, il est démontré que WACS est un bon outil pour le biologiste mais pourraît ne pas être assez précis pour être inséré au sein d’un réseau anti-collision. Associé à un monitorage de l’environnement acoustique, il est démontré que WACS est assez précis pour être inclus dans un réseau anti-collision, les degrés de liberté de WACS sont optimisés et la maille du réseau est identifiée

Modelling of ambient noise created by a shipping lane to prepare passive inversion: application to Ushant

The Ushant thermal front is a seasonal phenomenon which occurs from May to October in a shallow water environment (100m) of the Iroise Sea (off the coast of the north-western France). It corresponds to the boundary separating a well mixed inner shelf water from an open sea stratified water. To determine the dynamic of the front -or more basically the presence of a stratified or homogeneous water column- the possibility to use a shipping lane as a continuous acoustic source is studied. The originality of this work is to use a single receiver. Simulation results of sounds radiated by a shipping lane in a shallow water environment are presented, both for stratified and homogeneous water column. The corresponding pressure fields show a mean level difference in the frequency band 50-300 Hz. This feature will be used in the future as an observable to differentiate both environments, and thus passively detect the Ushant thermal front. One of the issue to get the mean level offset is to record the shipping lane noise without isolated ship interferences. As a consequence, an optimum mooring position to track the thermal front is suggested by the analysis of the vessel traffic from AIS data (Automatic Identification System)

Passive geoacoustic inversion of very shallow water environment with ship's noise: incoherent processing

In the context of the passive geoacoustic inversion, this manuscript proposes a new Inversion Method suitable for very shallow water environments (10 to 30 m) from the broadband noise produced by ships of opportunity. The solution is dedicated to a small number of hydrophones and is easy to implement. The interference patterns generated by the ship movement and the propagation properties are exploited to extract the relative dispersion curves on a chosen bandwidth then the geoaoustic inversion is performed. Here, we describe our algorithms and validate them on realistic synthetic data as well as on real data from a very shallow water trial performed off the Southern coast of Barcelona, Spain. Valuable results are obtained and allow to draw some way of improvement.Dans le contexte de l'inversion géoacoustique passive, nous proposons une méthode d'estimation des propriétés acoustiques d'un canal océanique très petits fonds (profondeur de 10 à 30 m) à partir du bruit large bande rayonné par des navires en transit. La solution est développée afin de conduire à un système de mesure minimisant le nombre d'hydrophones requis, pour cela elle utilise le mouvement des sources. À partir de l'observation acoustique de radiales centrées sur un hydrophone, les phénomènes d'interférences entre modes de propagation sont utilisés pour extraire les courbes de dispersion relatives du canal sur une bande fréquentielle choisie entre 50 et 500Hz. La contribution d'un navire est alors inversée pour fournir les propriétés du canal. Une description des algorithmes et de leurs implémentations est effectuée et leurs validations sont envisagées sur des données synthétiques réalistes ainsi que sur des données réelles issues d'une campagne expérimentale très petits fonds (profondeur~20 m) réalisée au sud de Barcelone à partir de petits navires d'opportunité constitués principalement de chalutiers. Les résultats produits sont encourageants et permettent de dresser des perspectives d'amélioration pour la méthode proposée

Measuring hearing in wild beluga whales

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in "The Effects of Noise on Aquatic Life II," edited by Arthur N. Popper, Anthony Hawkins, 729-735. New York, NY: Springer, 2016. doi: 10.1007/978-1-4939-2981-8_88.We measured the hearing abilities of seven wild beluga whales (Delphinapterus leucas) during a collection-and-release experiment in Bristol Bay, AK, USA. Here we summarize the methods and initial data from one animal, discussing the implications of this experiment. Audiograms were collected from 4-150 kHz. The animal with the lowest threshold heard best at 80 kHz and demonstrated overall good hearing from 22-110 kHz. The robustness of the methodology and data suggest AEP audiograms can be incorporated into future collection-and-release health assessments. Such methods may provide high-quality results for multiple animals facilitating population-level audiograms and hearing measures in new species.Project funding and field support provided by Georgia Aquarium and the National Marine Mammal Laboratory of the Alaska Fisheries Science Center (NMML/AFSC). Field work also supported by National Marine Fisheries Service Alaska Regional Office (NMFS AKR), WHOI Arctic Research Initiative, WHOI Ocean Life Institute, U.S. Fish and Wildlife Service, Bristol Bay Native Association, Alaska SeaLife Center, Shedd Aquarium and Mystic Aquarium. Audiogram analyses were funded by the Office of Naval Research award number N000141210203 (from Michael Weise)

David Hume on Banking and Hoarding

David Hume opposes banks and favors hoarding. The only bank he reluctantly approves of is a public, 100% reserve bank. Other banks increase money supply and prices, hindering exports and economic growth. For Hume, a 100% reserve public bank would lead to ‘‘the destruction of paper-credit’’ ([1752] 1985, p. 285), fostering economic growth instead by preventing inflation. Additionally, a 100% reserve bank hoards a large quantity of gold and silver, which is available in case of national emergency

In vitro studies and preliminary in vivo evaluation of silicified concentrated collagen hydrogels

Hybrid and nanocomposite silicacollagen materials derived from concentrated collagen hydrogels were evaluated in vitro and in vivo to establish their potentialities for biological dressings. Silicification significantly improved the mechanical and thermal stability of the collagen network within the hybrid systems. Nanocomposites were found to favor the metabolic activity of immobilized human dermal fibroblastswhile decreasing the hydrogel contraction. Cell adhesion experiments suggested that in vitro cell behavior was dictated by mechanical properties and surface structure of the scaffold. First-to-date in vivo implantation of bulk hydrogels in subcutaneous sites of rats was performed over the vascular inflammatory period. These materials were colonized and vascularized without inducing strong inflammatory response. These data raise reasonable hope for the future application of silicacollagen biomaterials as biological dressings.Fil: Desimone, Martín Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Hélary, Christophe. Université Pierre et Marie Curie; FranciaFil: Quignard, Sandrine. Université Pierre et Marie Curie; FranciaFil: Rietveld, Ivo B. Universite de Paris; FranciaFil: Bataille, Clement. Université de Versailles Saint-quentin-en-yvelines.; FranciaFil: Copello, Guillermo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Mosser, Gervaise. Université Pierre et Marie Curie; FranciaFil: Giraud Guille, Marie-Madeleine. Université Pierre et Marie Curie; FranciaFil: Livage, Jacques. Université Pierre et Marie Curie; FranciaFil: Meddahi Pellé, Anne. Université de Versailles Saint-quentin-en-yvelines.; FranciaFil: Coradin, Thibaud. Université Pierre et Marie Curie; Franci