東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back to Search results for [ null ]

Switch To: Labeled | MARC Mode | ISBD

Investigation of ocean acoustics usi...

Holmes, Jason David.

Linked to FindBook

Google Book

Amazon

博客來

Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties./
Author:	Holmes, Jason David.
Description:	315 p.
Notes:	Source: Dissertation Abstracts International, Volume: 67-05, Section: B, page: 2793.
Contained By:	Dissertation Abstracts International67-05B.
Subject:	Engineering, Mechanical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3218544
ISBN:	9780542704543

Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties.
Holmes, Jason David.

Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties. - 315 p.

Source: Dissertation Abstracts International, Volume: 67-05, Section: B, page: 2793.

Thesis (Ph.D.)--Boston University, 2007.

Sound propagation in shallow water is characterized by interaction with the oceans surface, volume, and bottom. In many coastal margin regions, including the Eastern U.S. continental shelf and the coastal seas of China, the bottom is composed of a depositional sandy-silty top layer. Previous measurements of narrow and broadband sound transmission at frequencies from 100 Hz to 1 kHz in these regions are consistent with waveguide calculations based on depth and frequency dependent sound speed, attenuation and density profiles. Theoretical predictions for the frequency dependence of attenuation vary from quadratic for the porous media model of M.A. Biot to linear for various competing models. Results from experiments performed under known conditions with sandy bottoms, however, have agreed with attenuation proportional to f 1.84, which is slightly less than the theoretical value of f2 [Zhou and Zhang, J. Acoust. Soc. Am. 117, 2494]. This dissertation presents a reexamination of the fundamental considerations in the Biot derivation and leads to a simplification of the theory that can be coupled with site-specific, depth dependent attenuation and sound speed profiles to explain the observed frequency dependence. Long-range sound transmission measurements in a known waveguide can be used to estimate the site-specific sediment attenuation properties, but the costs and time associated with such at-sea experiments using traditional measurement techniques can be prohibitive. Here a new measurement tool consisting of an autonomous underwater vehicle and a small, low noise, towed hydrophone array was developed and used to obtain accurate long-range sound transmission measurements efficiently and cost effectively. To demonstrate this capability and to determine the modal and intrinsic attenuation characteristics, experiments were conducted in a carefully surveyed area in Nantucket Sound. A best-fit comparison between measured results and calculated results, while varying attenuation parameters, revealed the estimated power law exponent to be 1.87 between 220.5 and 1228 Hz. These results demonstrate the utility of this new cost effective and accurate measurement system. The sound transmission results, when compared with calculations based on the modified Biot theory, are shown to explain the observed frequency dependence.

ISBN: 9780542704543Subjects--Topical Terms:

783786
Engineering, Mechanical.

Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties.
LDR:03298nmm 2200289 4500 001 1826018
005 20061206120647.5
008 130610s2007 eng d
020 $a 9780542704543
035 $a (UnM)AAI3218544
035 $a AAI3218544
040 $a UnM $c UnM
100 1 $a Holmes, Jason David. $3 1914990
245 1 0 $a Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties.
300 $a 315 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-05, Section: B, page: 2793.
500 $a Adviser: William M. Carey.
502 $a Thesis (Ph.D.)--Boston University, 2007.
520 $a Sound propagation in shallow water is characterized by interaction with the oceans surface, volume, and bottom. In many coastal margin regions, including the Eastern U.S. continental shelf and the coastal seas of China, the bottom is composed of a depositional sandy-silty top layer. Previous measurements of narrow and broadband sound transmission at frequencies from 100 Hz to 1 kHz in these regions are consistent with waveguide calculations based on depth and frequency dependent sound speed, attenuation and density profiles. Theoretical predictions for the frequency dependence of attenuation vary from quadratic for the porous media model of M.A. Biot to linear for various competing models. Results from experiments performed under known conditions with sandy bottoms, however, have agreed with attenuation proportional to f 1.84, which is slightly less than the theoretical value of f2 [Zhou and Zhang, J. Acoust. Soc. Am. 117, 2494]. This dissertation presents a reexamination of the fundamental considerations in the Biot derivation and leads to a simplification of the theory that can be coupled with site-specific, depth dependent attenuation and sound speed profiles to explain the observed frequency dependence. Long-range sound transmission measurements in a known waveguide can be used to estimate the site-specific sediment attenuation properties, but the costs and time associated with such at-sea experiments using traditional measurement techniques can be prohibitive. Here a new measurement tool consisting of an autonomous underwater vehicle and a small, low noise, towed hydrophone array was developed and used to obtain accurate long-range sound transmission measurements efficiently and cost effectively. To demonstrate this capability and to determine the modal and intrinsic attenuation characteristics, experiments were conducted in a carefully surveyed area in Nantucket Sound. A best-fit comparison between measured results and calculated results, while varying attenuation parameters, revealed the estimated power law exponent to be 1.87 between 220.5 and 1228 Hz. These results demonstrate the utility of this new cost effective and accurate measurement system. The sound transmission results, when compared with calculations based on the modified Biot theory, are shown to explain the observed frequency dependence.
590 $a School code: 0017.
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Engineering, Marine and Ocean. $3 1019064
650 4 $a Engineering, Electronics and Electrical. $3 626636
690 $a 0548
690 $a 0547
690 $a 0544
710 2 0 $a Boston University. $3 1017454
773 0 $t Dissertation Abstracts International $g 67-05B.
790 1 0 $a Carey, William M., $e advisor
790 $a 0017
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3218544