2026-09-18T22:51:48Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/361972022-01-13T07:54:36Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Nicholas C. Makris.
Lee, Sunwoong
Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
2007-02-21T12:04:14Z
2007-02-21T12:04:14Z
2006
2006
http://hdl.handle.net/1721.1/36197
76877642
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.
Includes bibliographical references (p. 211-225).
Methods are developed for passive source localization and environmental parameter estimation in seismo-acoustic waveguides by exploiting the dispersive behavior of guided wave propagation. The methods developed are applied to the terrestrial continental shelf environment and the Jovian icy satellite Europa. The thesis is composed of two parts. First, a method is derived for instantaneous source-range estimation in a horizontally-stratified ocean waveguide from passive beam-time intensity data obtained after conventional plane-wave beamforming of acoustic array measurements. The method is advantageous over existing source localization methods, since (1) no knowledge of the environment is required except that the received field should not be dominated by purely waterborne propagation, (2) range can be estimated in real time with little computational effort beyond plane-wave beamforming, and (3) array gain is fully exploited. Second, source range estimation and environmental parameter inversion using passive echo-sounding techniques are discussed and applied to Europa. We show that Europa's interior structure may be determined by seismo-acoustic echo sounding techniques by exploiting natural ice fracturing events or impacts as sources of opportunity.
(cont.) A single passive seismic sensor on Europa's surface may then be used to estimate the thickness of its ice shell and the depth of its subsurface ocean. To further understand the seismo-acoustic characteristics of natural sources on Europa, a fracture mechanics model is developed for the initiation and propagation of a crack through a porous ice layer of finite thickness under gravitational overburden. It is found that surface cracks generated in response to a tidally induced stress field may penetrate through the entire outer brittle layer if a subsurface ocean is present on Europa. While Europa's ice is likely highly porous and fractured, our current caculations show that porosity-induced scattering loss of ice-penetrating radar waves should not be significant.
by Sunwoong Lee.
Ph.D.
225 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Mechanical Engineering.
Efficient localization in a dispersive waveguide : applications in terrestrial continental shelves and on Europa
Thesis
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<Abstract>Methods are developed for passive source localization and environmental parameter estimation in seismo-acoustic waveguides by exploiting the dispersive behavior of guided wave propagation. The methods developed are applied to the terrestrial continental shelf environment and the Jovian icy satellite Europa. The thesis is composed of two parts. First, a method is derived for instantaneous source-range estimation in a horizontally-stratified ocean waveguide from passive beam-time intensity data obtained after conventional plane-wave beamforming of acoustic array measurements. The method is advantageous over existing source localization methods, since (1) no knowledge of the environment is required except that the received field should not be dominated by purely waterborne propagation, (2) range can be estimated in real time with little computational effort beyond plane-wave beamforming, and (3) array gain is fully exploited. Second, source range estimation and environmental parameter inversion using passive echo-sounding techniques are discussed and applied to Europa. We show that Europa's interior structure may be determined by seismo-acoustic echo sounding techniques by exploiting natural ice fracturing events or impacts as sources of opportunity.</Abstract>
<Abstract>(cont.) A single passive seismic sensor on Europa's surface may then be used to estimate the thickness of its ice shell and the depth of its subsurface ocean. To further understand the seismo-acoustic characteristics of natural sources on Europa, a fracture mechanics model is developed for the initiation and propagation of a crack through a porous ice layer of finite thickness under gravitational overburden. It is found that surface cracks generated in response to a tidally induced stress field may penetrate through the entire outer brittle layer if a subsurface ocean is present on Europa. While Europa's ice is likely highly porous and fractured, our current caculations show that porosity-induced scattering loss of ice-penetrating radar waves should not be significant.</Abstract>
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