Consulta: subjectFacets:"Sonar"
Registros recuperados: 10
Data/hora: 01/06/2024 08:06:29

Apports de l''imagerie fournie par le sonar a balayage lateral a la connaissance de la dynamique sedimentaire en Baie de Seine
Provedor de dados: 5
Autores: Auffret, J; D'Ozouville, L.
Continous process recording of lateral scanning sonar allows the observation of bottom sediments repartition contrasts. Their heterogeneity and evolution, the nature of contacts between different sediment deposits can be studied by this instrument, which completes the different techniques used for the sediment dynamics study.
Tipo: Text
Palavras-chave: Sediment composition; Sediment distribution; Sonar imagery; Sediment dynamics; Sonar.
Ano: 1985
URL: http://archimer.ifremer.fr/doc/1985/acte-1284.pdf

Observing the ocean interior in support of integrated management
Provedor de dados: 5
Autores: Trenkel, Verena; Handegard, Nils Olav; Weber, Thomas C.
Active- and passive-acoustic methods are widely used tools for observing, monitoring, and understanding marine ecosystems. From 25 to 28 May 2015, 214 scientists from 31 nations gathered for an ICES symposium on Marine Ecosystem Acoustics (SoME Acoustics) to discuss three major themes related to acoustic observations of marine ecosystems: (i) recent developments in acoustic and platform technologies; (ii) acoustic characterisation of aquatic organisms, ecosystem structure, and ecosystem processes; and (iii) contribution of acoustics to integrated ecosystem assessments and management. The development of, and access to new instruments, such as broad bandwidth systems, enables insightful ecological studies and innovative management approaches. Unresolved...
Tipo: Text
Palavras-chave: Acoustics; Broadband; Multi-frequency; Passive and active acoustics; Ecosystem approach to management; Ecosystem monitoring; Pelagic ecosystem; Echosounder; Sonar.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00347/45820/45921.pdf

Etude des conséquences du fonctionnement de la centrale de Gravelines sur le milieu marin 1986
Provedor de dados: 5
Autores: Gentien, Patrick; Gros, Philippe; Le Fevre-lehoerff, Geneviève.
Une étude de rejet d'eau chaude (chlorée) du Centre de Production nucléaire a été effectuée selon deux méthodologies.
Tipo: Text
Palavras-chave: Centrale nucléaire; Gravelines; Impact; Dilution; Phytoplancton; Sonar; Nuclear power plant; Gravelines; Impact; Dilution; Phytoplankton; Sonar.
Ano: 1986
URL: http://archimer.ifremer.fr/doc/00006/11722/8391.pdf

Three dimensional characteristics of young-of-year pelagic fish schools in lake
Provedor de dados: 5
Autores: Guillard, Jean; Brehmer, Patrice; Colon, Michel; Guennegan, Yvon.
Fish schools are aggregative structures encountered in all types of aquatic environments but have as yet been little studied in freshwaters except at small spatial scales. This study represents the three dimensional description of juvenile fish schools (Perca fluviatilis and Rutilus rutilus) in a lake environment using high resolution multibeam sonar system operating at a frequency of 455 kHz, composed of 60 beams of 1.5 degrees allowing a 90 degrees observation plane. The in situ diurnal schooling behaviour of young-of-the-year fish of both species is confirmed. The morphological, energetic and spatial variables of these schools are described and related to one another. The structures described are of the same order of magnitude as those described in the...
Tipo: Text
Palavras-chave: Annecy Lake; Rutilus rutilus; Perca fluviatilis; Sonar; 3 D structure; Shoaling behaviour.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1661.pdf

Acoustique sous-marine. Présentation et applications
Provedor de dados: 5
Autores: Lurton, Xavier.
Sound waves are the only practical means of remote investigation and transmission in seawater. All along the XXth century, underwater acoustics became one of the major technologies used for exploration and exploitation of the oceans for scientific, industrial, or military purposes. It is nowadays able to play, inside the oceans, the roles devoted to radio and radar in atmosphere and space, and is widely employed in the fields of navigation, fisheries, defence, oceanography and ocean engineering. This book presents, in a clear and concise way, the basic physical phenomena governing underwater acoustical waves, the general features of sonar systems, and an overview of their applications.
Tipo: Text
Palavras-chave: Acoustique sous-marine; Propagation; Traitement du signal; Sonar; Sondeur; Underwater acoustics; Propagation; Signal processing; Sonar; Echosounder.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00017/12790/9731.pdf

A Measurement Quality Factor for Swath Bathymetry Sounders
Provedor de dados: 5
Autores: Lurton, Xavier; Augustin, Jean-marie.
The quality estimation associated with individual soundings measured and computed by swath bathymetry sonars is a paramount issue which is most often imperfectly addressed today by sonar manufacturers. In this paper, a unified definition is proposed for a quality factor usable for all swath bathymetry sonars; the depth-relative error is directly estimated from the signal characteristics used in the sounding computation. The basic algorithms are presented for both phase-difference (oblique incidence) and amplitude (normal incidence) detection, and can be readily implemented in any swath bathymetry system using these detection principles. This approach gives a direct access to the objective bathymetric performance of individual soundings, and hence avoids...
Tipo: Text
Palavras-chave: Bathymetry; Interferometry; Multibeam echosounder (MBES); Sonar.
Ano: 2010

Delphinid whistle production and call matching during playback of simulated military sonar
Provedor de dados: 5
Autores: De Ruiter, Stacy; Boyd, Ian L.; Claridge, Diane E.; Clark, Christopher W.; Gagnon, Chuck; Southall, Brandon L.; Tyack, Peter L.
In 2007 and 2008, controlled exposure experiments were performed in the Bahamas to study behavioral responses to simulated mid-frequency active sonar (MFA) by three groups of odontocetes: false killer whales, Pseudorca crassidens; short-finned pilot whales, Globicephala macrorhynchus; and melon-headed whales, Peponocephala electra. An individual in each group was tagged with a Dtag to record acoustic and movement data. During exposures, some individuals produced whistles that seemed similar to the experimental MFA stimulus. Statistical tests were thus applied to investigate whistle-MFA similarity and the relationship between whistle production rate and MFA reception time. For the false killer whale group, overall whistle rate and production rate of the...
Tipo: Text
Palavras-chave: Noise; Sonar; Mid-frequency sonar; Whistle; Behavioral effects; Sound production; Pseudorca crassidens; Globicephala macrorhynchus; Peponocephala electra; False killer whale; Pilot whale; Melon-headed whale.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00138/24974/23185.pdf

Analyse des risques pour les mammifères marins liés à l'emploi des méthodes acoustiques en océanographie
Provedor de dados: 5
Autores: Lurton, Xavier; Antoine, Loic.
The use of acoustical systems in various human activities in the ocean (industry, defence, science) raises the issue of their impact upon marine mammals populations. Several serious accidents linked to the use of naval sonars led the military, industrial and scientific communities to investigate the potential dangers of their own activity.    This report aims at identifying the risks for the cetaceans linked to the use of acoustic and seismic systems currently used for oceanographic science. The analysis proposed here stays within the frame of bibliography synthesis and elementary modelling, and brings no new scientific elements on the topic. An overview of the status of cetacean populations is given first, with a summary of the possible acoustical...
Tipo: Text
Palavras-chave: Seismics; Sonar; Acoustics; Oceanography; Acoustical methods; Auditory threshold; Stranding; Acoustical risks; Marine mammals.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/rapport-2390.pdf

Multibeam sonar detection of suspended mussel culture grounds in the open sea: Direct observation methods for management purposes
Provedor de dados: 5
Autores: Brehmer, Patrice; Vercelli, Catherine; Gerlotto, Francois; Sanguinede, Fabien; Pichot, Yves; Guennegan, Yvon; Buestel, Dominique.
The exploitation of offshore mussel farms is becoming important throughout the world, but monitoring this activity remains a difficult task. Here, we propose a specific method for this purpose. A total of 140 long-lines were monitored on a mussel culture ground in the French Mediterranean Sea during four experimental surveys deploying multibeam sonar devices mounted on poles (Reson Seabat 6012, 455 kHz) on small boats. This allowed geo-referenced observations to be made of the submerged mussel long-lines, as well as three-dimensional (3D) drawings of the long-line structures and the sea bed shapes, using long-line longitudinal sonar sampling. Three sonar data-analysis methods were applied: (i) direct two-dimensional (2D) visual interpretation of raw sonar...
Tipo: Text
Palavras-chave: Management; Sonar; Open sea; Long line; Mussel.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1672.pdf

Observaciones sobre el comportamiento de la merluza (Merluccius hubbsi) durante la pesca de arrastre
Provedor de dados: 20
Autores: Casarsa, L.; Madirolas, A.
The normal behavioral patterns of several fish species is altered during trawling affecting the fish spatial distribution. Sonar methods were carried out in this research work in order to study the reaction of reproductive concentrations of the Argentine hake (Merluccius hubbsi) during mid-water and bottom fishing trawls. Observations made from a trawl sonar mounted on the headrope of an ENGEL (35 m) bottom trawl, showed that this species concentrates at the lower-central sector of the net mouth. During daytime trawls fish schools with a vertical distribution exceeding ten meters were observed entering the trawl within the first two meters from the bottom. Some observations during pelagic trawls carried out at night, showed no specific pattern at the net...
Tipo: Journal Contribution
Palavras-chave: Behaviour; Bottom trawling; Sonar; Echo surveys; Vertical distribution; Behaviour; Http://aims.fao.org/aos/agrovoc/c_868.
Ano: 2007
URL: http://hdl.handle.net/1834/2517