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Acoustic phase measurements from volume scatter in the oceanHuston, Robert Delmar 12 November 2014 (has links)
A primary goal of this thesis has been to demonstrate that stable, useful
measurements of the orientation of the acoustic signal vector as a function of
range and time can be obtained from ocean backscatter, and that this orientation,
or acoustic phase, can be related to the local sound speed distribution.
Such a measurement is quite distinct from the related problem of detecting the
rate of phase change, which forms the basis of Doppler technology. Doppler
measurements can be made using echoes from a single point, or a sparsely
distributed set of targets. Consistent and useful measurement of absolute phase,
is inherently more difficult, since it depends upon the positions of individual scatterers, which are normally random and sparse relative to the acoustic
wavelength. / Graduate
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Geophysical studies of sediments in waters near Hong Kong and in the Gulf of St. LawrenceWong, How-Kin. January 1967 (has links)
Thesis (Ph.D.)--University of Hong Kong, 1968. / Also available in print.
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Acoustically induced fluid flows in a model fish earKotas, Charlotte Walker. January 2008 (has links)
Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Co-Chair: Rogers, Peter; Committee Co-Chair: Yoda, Minami; Committee Member: Giddens, Don; Committee Member: Sotiropoulos, Fotis; Committee Member: Trivett, David; Committee Member: Yen, Jeanette. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Report on the Office of Naval Research Shallow Water Acoustics Workshop, April 24-26, 1991 /Frisk, George V. January 1900 (has links)
"January 1992." / "Technical report." "Funding was provided by the Office of Naval Research through Contract no. N00014-91-J-1776." Includes bibliographical references (p. 7).
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Report on the Office of Naval Research USA-China Conference on Shallow Water Acoustics, December 18-21, 1995Chiu, Ching-Sang. Denner, Warren W. January 1997 (has links)
"January 1997." Thesis (Ph. D.)--Naval Postgraduate School, 1996. / "Prepared for: Office of Naval Research, Arlington, VA 22217-5660."
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Undersea acoustic propagation channel estimation /Dessalermos, Spyridon. January 2005 (has links) (PDF)
Thesis (M.S. in Electrical Engineering and M.S. in Applied Physics)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Joseph Rice, Roberto Cristi. Includes bibliographical references (p. 117-119). Also available online.
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Pulsed parabolic equation model of acoustic transmission (PPEMAT)Acebo, Alicia Gonzalez 08 April 1986 (has links)
Underwater sound is very important in the field of oceanography where it is used for remote sensing in much the same way that radar is used in atmospheric studies. One way to mathematically model sound propagation in the ocean is by using the parabolic-equation method, a technique that allows range dependent environmental parameters. More importantly, this method can model sound transmission where the source emits either a pure tone or a short pulse of sound. Based on the parabolic approximation method and using the split-step Fourier algorithm, a computer model for underwater sound propagation was designed and implemented. This computer model differs from previous models in its use of the interactive mode, structured programming, modular design, and state-of-the-art graphics displays. In addition, the model maximizes the efficiency of computer time through synchronization of loosely coupled dual processors and the design of a restart capability. Since the model is designed for adaptability and for users with limited computer skills, it is anticipated that it will have many applications in the scientific community.
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Multiresolution Signal Cross-correlationNovaes, Marcos (Marcos Nogueira) 12 1900 (has links)
Signal Correlation is a digital signal processing technique which has a wide variety of applications, ranging from geophysical exploration to acoustic signal enhancements, or beamforming. This dissertation will consider this technique in an underwater acoustics perspective, but the algorithms illustrated here can be readily applied to other areas. Although beamforming techniques have been studied for the past fifty years, modern beamforming systems still have difficulty in operating in noisy environments, especially in shallow water.
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The Design and Analysis of a Rare Earth Iron Magnetostrictive Underwater Sound TransducerMeeks, Steven Wayne 01 January 1977 (has links) (PDF)
The design and analysis of a low-frequency, resonant, tonpilz type, rare earth iron underwater sound transducer using rods of Tb.27Dy.73Fe1.95 are described. An equivalent circuit is presented which predicts the performance of the transducer in the presence of eddy currents and demagnetization. The effect of eddy currents on the impedance of a rod is discussed. The predicted performance of a laminated transducer is compared with that of an unlaminated transducer. The performance of the rare earth iron transducer is compared with the performance of the same transducer with identical ceramic active elements. Data on transmitting current response, transmitting voltage response, free field voltage sensitivity, coupling coefficient, efficiency, and linearity are presented. Advantages, disadvantages, and possible uses of rare earth iron material are discussed.
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Acoustic Techniques for Tuna Biomass EstimationLadino Velásquez, Anderson 02 September 2024 (has links)
[ES] Esta Tesis Doctoral aborda una problemática crítica en el ámbito de la acuicultura y la pesca sostenible del atún, centrándose en la identificación de especies y la estimación de la biomasa. La importancia de este enfoque radica en su relevancia para la gestión efectiva de los recursos marinos y la conservación de los océanos, alineándose con los Objetivos de Desarrollo Sostenible de las Naciones Unidas. Un aspecto fundamental de esta Tesis es la aplicación de técnicas de simulación acústica. A través de simulaciones numéricas, se exploran diversos aspectos de la acústica submarina, desde la propagación de ondas acústicas hasta la retrodispersión acústica en diferentes estructuras y tejidos de especies marinas. Estas simulaciones permiten comprender y predecir cómo las propiedades acústicas de los objetos influyen en la respuesta acústica.
El objetivo central de esta Tesis de investigación es desarrollar y aplicar técnicas acústicas para abordar la problemática de la identificación de especies y la estimación de la biomasa. Cada capítulo aborda aspectos específicos de la acústica submarina, desde las bases teóricas de los ultrasonidos en medios líquidos, la influencia de factores como el tamaño y la forma de los peces en la retrodispersión acústica, hasta la medición de las propiedades acústicas de los tejidos y cómo estas propiedades afectan la retrodispersión acústica. La Tesis también incluye un estudio de la combinación de los métodos numéricos de simulación para analizar la retrodispersión acústica en geometrías complejas. Por otra parte, se realizan estudios sobre el desarrollo temprano de larvas de peces, monitorización de la inflación de la vejiga natatoria y la variación del Target Strength en respuesta a diferentes duraciones de pulso en ecosondas.
Por lo tanto, la investigación desarrollada en esta Tesis abre un camino en el campo de la acuicultura y la pesca sostenible del atún, permitiendo mejorar significativamente la identificación de especies y la estimación de la biomasa. La aplicación de técnicas de simulación acústica y la comprensión profunda de la acústica submarina proporcionan un enfoque interdisciplinario que contribuye a resolver desafíos críticos en la gestión de recursos marinos. Estos avances no solo impulsan la eficiencia en la acuicultura y la pesca sostenible, sino que también fortalecen la conservación de los océanos y la biodiversidad marina. / [CA] Aquesta Tesi Doctoral aborda una qüestió crítica en el camp de l'acuicultura i la pesca sostenible de la tonyina, centrant-se en la identificació d'espècies i l'estimació de biomassa. La importància d'aquest enfocament rau en la seva rellevància per a la gestió efectiva dels recursos marins i la conservació oceànica, alineant-se amb els Objectius de Desenvolupament Sostenible de les Nacions Unides. Un aspecte fonamental d'aquesta Tesi és l'aplicació de tècniques de simulació acústica. Mitjançant simulacions numèriques, s'exploren diversos aspectes de l'acústica submarina, des de la propagació d'ones acústiques fins a la retrodispersió acústica en les diferents estructures i teixits que constitueixen algunes espècies. Aquestes simulacions ens permeten comprendre i predir com les propietats acústiques dels objectes sota estudi influeixen en la resposta acústica.
L'objectiu central d'aquesta Tesi de recerca és desenvolupar i aplicar tècniques acústiques per abordar el problema de la identificació d'espècies i l'estimació de biomassa. Cada capítol aborda aspectes específics de l'acústica submarina, des dels fonaments teòrics de la propagació d'ones acústiques en medis líquids fins a la influència de factors com la mida i la forma dels peixos en la retrodispersió acústica, així com la mesura de les propietats acústiques dels teixits i com aquestes propietats afecten la retrodispersió acústica. La Tesi també inclou un estudi de la combinació de mètodes de simulació numèrica per analitzar la retrodispersió acústica en geometries complexes. A més, es realitzen estudis sobre el desenvolupament primerenc de les larves de peixos, el seguiment de la inflació de la bufeta natatòria i la variació de la Força de l'Objectiu en resposta a diferents durades de pols en ecosondes.
Per tant, la recerca desenvolupada en aquesta Tesi contribueix a obrir una nova via en el camp de l'acuicultura i la pesca sostenible de la tonyina, aportant millores significatives en la identificació d'espècies i l'estimació de biomassa. L'aplicació de tècniques de simulació acústica i un profund coneixement de l'acústica submarina proporcionen un enfocament interdisciplinari que contribueix a abordar desafiaments crítics en la gestió de recursos marins. Aquests avenços no només milloren l'eficiència en l'acuicultura i la pesca sostenible, sinó que també reforcen la conservació oceànica i la biodiversitat marina. / [EN] This Doctoral Thesis addresses a critical issue in the field of aquaculture and sustainable tuna fishing, focusing on species identification and biomass estimation. The significance of this approach lies in its relevance to effective marine resource management and ocean conservation, aligning with the United Nations' Sustainable Development Goals. A fundamental aspect of this Thesis is the application of acoustic simulation techniques. Through numerical simulations, various aspects of underwater acoustics are explored, from the propagation of acoustic waves to acoustic backscatter in different structures and tissues of marine species. These simulations enable us to understand and predict how the acoustic properties of the targets influence the acoustic response.
The central objective of this research Thesis is to develop and apply acoustic techniques to address the issue of species identification and biomass estimation. Each chapter addresses specific aspects of underwater acoustics, from the theoretical foundations of ultrasounds propagation in liquid media to the influence of factors such as the size and shape of fish on acoustic backscatter, as well as the measurement of acoustic properties of tissues and how these properties affect acoustic backscatter. The Thesis also includes a study of the combination of numerical simulation methods to analyse acoustic backscatter in complex geometries. Furthermore, studies are conducted on the early development of fish larvae, monitoring of swimbladder inflation, and the variation in Target Strength in response to different pulse durations in echosounders.
Therefore, the research developed in this Thesis opens a new avenue in the field of aquaculture and sustainable tuna fisheries, allowing for significant improvements in species identification and biomass estimation. The application of acoustic simulation techniques and a deep understanding of underwater acoustics provide a interdisciplinary approach that contributes to addressing critical challenges in marine resource management. These advances not only enhance efficiency in aquaculture and sustainable fishing but also strengthen ocean conservation and marine biodiversity. / Ladino Velásquez, A. (2024). Acoustic Techniques for Tuna Biomass Estimation [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/207341
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