Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 19 of 19 for “"Hydrophone Array"”.
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Sub-bottom profiling using an Autonomous Underwater Vehicle equipped with a sound source and towed hydrophone array
… vehicle equipped with a source and a towed array is an excellent method to finely survey large areas of the ocean bottom with minimal interference from the water column. This approach has the benefit of being able to determine the range dependence of the sub-bottom on a meter-by-meter scale …
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Sub-Bottom Profiling Using an Autonomous Underwater Vehicle Equipped With a Sound Source and Towed Hydrophone Array
… vehicle equipped with a source and a towed array is an excellent method to finely survey large areas of the ocean bottom with minimal interference from the water column. This approach has the benefit of being able to determine the range dependence of the sub-bottom on a meter-by-meter scale …
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Design and Development of a Hydrophone Array for an Autonomous Underwater Vehicle Capable of Real-Time Detection and Tracking of Surface Vessels
Passive acoustic systems composed of hydrophone array have been shown useful for underwater acoustic source detection and tracking. The work presented here demonstrates use of a passive acoustic system for an Autonomous Underwater Vehicle (AUV) composed of a 2D hydrophone array along with a post …
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Prediction of the beamformed acoustic ray arrival structure for the 1992 Barents Sea coastal tomography test
… from a near bottom sound source to a vertical hydrophone array was simulated based on three-dimensional ray theory. based on three- dimensional ray theory. Through numerical raytracing, followed by eigenray searches and estimations of ray amplitudes, searches and estimations of ray amplitudes, …
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High frequency sonar components of normal and hearing impaired dolphins
… of capturing sonar signals by means of a two-hydrophone array, and a digital video camera in a submersible housing. Cooperation with marine biologists at SSC San Diego enabled the sampling of three animals performing echolocation tasks. Their sonar signals, transmissions of rapid high …
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Forward sound propagation around seamounts : application of acoustic models to the Kermit-Roosevelt and Elivs seamounts
… and scattering by the seamounts. A towed hydrophone array, with 64 sensors cut for 250Hz (3m spacing), was used to measure the signals transmitted from the aforementioned broadband sources at many locations around the Kermit-Roosevelt and Elvis seamounts. Utilizing the measured broadband …
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Sound propagation around underwater seamounts
… around the seamount at megameter ranges. A hydrophone array was towed around the seamount to locations which allowed measurement of the perturbation zone. Results from the method developed in this thesis show that the size and shape of the perturbation zone measured coincides with …
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Sound propagation around underwater seamounts
… around the seamount at megameter ranges. A hydrophone array was towed around the seamount to locations which allowed measurement of the perturbation zone. Results from the method developed in this thesis show that the size and shape of the perturbation zone measured coincides with …
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Modal analysis of vertical array receptions for the Heard Island Feasibility Test
… 1991 Heard Island Feasibility Test, a vertical hydrophone array deployed off Monterey, CA, recorded transmissions from a low-frequency acoustic source nearly 18,000 km away. By determining the modal structure of the received transmissions, it is possible to characterize the physics of such long …
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Reducing mechanical and flow-induced noise in the surface suspended acoustic receiver
… ratios in the frequency band of the hydrophones. This thesis details efforts to reduce the hydrophone noise level by combining the analysis of experimental data with the results from numerical models. Experiments were conducted to quantify both the frequency content and magnitude of …
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Sound propagation around underwater seamounts
… respectively. The receiver was a towed hydrophone array with 3 m sensor spacing, cut for 250 Hz. BASSEX is the first experiment to measure acoustic arrival patterns in the scattered field of a seamount at many locations at sound path ranges of order 500 km, utilizing a rich bathymetry …
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Oceanic lithosphere magnetization : marine magnetic investigations of crustal accretion and tectonic processes in mid-ocean ridge environments
… hydroacoustic waves (T-phases) recorded by a hydrophone array. Observations and ray trace models of event propagation show bathymetric blockage along propagation paths, but suggest current models of T-phase excitation and propagation need to be improved to explain observed characteristics of …
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Whistle use and whistle sharing by allied male bottlenose dolphins, Tursiops truncatus
… may not represent its complete repertoire. A hydrophone array was used to record whistles of free-swimming, socializing individuals to compare to the whistles produced by those animals in isolation. There was no significant difference in the whistle repertoires of restrained vs. free-swimming …
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Ocean acoustic applications of an autonomous underwater vehicle at the New England Shelfbreak
… with an onboard 2.5-4.5 kHz transducer and towed hydrophone array, was deployed among a network of oceanographic and transceiver moorings. Acoustic signals transmitted and received throughout this network were used to analyze the physical links between environmental variability and acoustic …
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Oceanic lithosphere magnetization : marine magnetic investigations of crustal accretion and tectonic processes in mid-ocean ridge environments
… hydroacoustic waves (T-phases) recorded by a hydrophone array. Observations and ray trace models of event propagation show bathymetric blockage along propagation paths, but suggest current models of T-phase excitation and propagation need to be improved to explain observed characteristics of …
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Forward sound propagation around seamounts : application of acoustic models to the Kermit-Roosevelt and Elvis seamounts
… and scattering by the seamounts. A towed hydrophone array, with 64 sensors cut for 250Hz (3m spacing), was used to measure the signals transmitted from the aforementioned broadband sources at many locations around the Kermit-Roosevelt and Elvis seamounts. Utilizing the measured broadband …
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Acoustical characterization of glacierized fjords
… October 2016 and May 2017 from an underwater hydrophone array moored 500 m from LeConte Glacier. Ambient noise levels (ANL) from recordings were clustered, revealing relationships between ambient noise and the speed of icebergs above the mooring and with calving events. In particular, the …
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Tracking sperm whales using passive acoustics and particle filters
… academic institutions from boats or ships towing hydrophone arrays often comprising only two elements. The arrival time-delay of the acoustic wavefront from the vocalising animals across the array aperture is computed, often using freely available software, and typically regarded as the bearing of …
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Sensor Array Processing with Manifold Uncertainty
… realizable source locations for a given array configuration is referred to as the array manifold. In this thesis, array manifold ambiguities for linear arrays of omni-directional sensors in non-dispersive fields are considered. </p><p>First, the problem of underwater a hydrophone array …