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| 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 |
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| David, P; Guerin-ancey, O; Oudot, G; Van Cuyck, Jp. |
| Although zooplanktonic organisms nearly have the acoustical impedance of water, they backscatter the sound. Strong acoustical echoes from salps were recorded in the Weddell sea at 150 kHz (1992), in the Indian ocean at 12 kHz (1994) and in the Mediterranean at 120 and 38 kHz (1996). Sphere and cylinder models were applied to estimate the salp target strength. The salp is modelled by a cylindrical gelatinous body (length L) and a spherical nucleus (radius a). Backscattering from each part was estimated individually. With a detection threshold of -100 dB, the minimum body length and the minimum radius of nucleus to be theoretically detected were estimated for each of the following frequencies: 12, 38, 120 and 150 kHz. A small salp (L = 14 rum and a = I mm)... |
| Tipo: Text |
Palavras-chave: Salpe; Target strength; Acoustique sous-marine; Salp; Target strength; Underwater acoustics. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/00322/43341/42886.pdf |
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