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- Title
- Boundary reflection coefficient estimation from depth dependence of the acoustic Green's function.
- Creator
- Conrad, Alexander., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Sound propagation in a waveguide is greatly dependent on the acoustic properties of the boundaries. The effect of these properties can be described by a bottom reflection coefficient RB, and surface reflection coefficient RS. Two methods for estimating reflection coefficients are used in this research. The first, the ratio method, is based on the variations of the Green's function with depth utilizing the ratio of the wavenumber spectra at two depths. The second, the pole method, is based on...
Show moreSound propagation in a waveguide is greatly dependent on the acoustic properties of the boundaries. The effect of these properties can be described by a bottom reflection coefficient RB, and surface reflection coefficient RS. Two methods for estimating reflection coefficients are used in this research. The first, the ratio method, is based on the variations of the Green's function with depth utilizing the ratio of the wavenumber spectra at two depths. The second, the pole method, is based on the wavenumbers of the modal peaks in the spectrum at a particular depth. A method to invert for sound speed and density is also examined. Estimates of RB and RS based on synthetic data by the ratio method were very close to their predicted values, especially for higher frequencies and longer apertures. The pole method returned less precise estimates though with longer apertures, the estimates were better. Using experimental data, results of the pole method as well a geoacoustic inversion technique based on them were mixed. The ratio method was used to estimate RS based on the actual data and returned results close to the predicted phase of p.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/3164094
- Subject Headings
- Underwater acoustics, Acoustic surface waves, Green's functions, Electromagnetic waves, Mathematics, Wave equation, Numerical solutions
- Format
- Document (PDF)
- Title
- Geoacoustic inversion of subbottom channels using mulitple frequency input parameters.
- Creator
- Weeks, Rebecca., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This thesis investigates inversion techniques used to determine the geoacoustic properties of a shallow-water waveguide. The data used were obtained in the Shallow Water '06 Modal Mapping Experiment in which four buoys drifted over a system of subbottom channels. The method used was perturbative inversion using modal eigenvalues as input parameters, which were found using an autoregressive spectral estimator. This work investigates the differences between a "channel" region and a "no channel"...
Show moreThis thesis investigates inversion techniques used to determine the geoacoustic properties of a shallow-water waveguide. The data used were obtained in the Shallow Water '06 Modal Mapping Experiment in which four buoys drifted over a system of subbottom channels. The method used was perturbative inversion using modal eigenvalues as input parameters, which were found using an autoregressive spectral estimator. This work investigates the differences between a "channel" region and a "no channel" region based on an inferred stratigraphic model. Inversions were performed on data from a single buoy both at individual frequencies and multiple frequencies simultaneously. Since the use of multiple frequencies and a certain set of constraints proved to be an effective method of inversion, the method was applied to data from the other three buoys as well. It is shown that the "channel" and "no channel" regions have significantly different sound speed profiles.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/1930486
- Subject Headings
- Oceanographic buoys, Stochastic processes, Acoustic surface waves, Underwater acoustics, Wave equation, Numerical solutions
- Format
- Document (PDF)
- Title
- A Study of the Underwater Acoustic Propagation in a Turning Basin Modeled as a Three-Dimensional Duct Closed at One End Using the Method of Images.
- Creator
- Staska, Matthew D., Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A computer-efficient model of the underwater acoustic propagation m a shallow, three-dimensional duct closed at one end has been developed using the method of images. Presented in this research is the development of this three-dimensional method of images analysis for a rectangular duct. Using this analysis, a model of the impulse response of the acoustic channel is constructed. Also presented in this work is the actual impulse response collected during field experimentation in the south...
Show moreA computer-efficient model of the underwater acoustic propagation m a shallow, three-dimensional duct closed at one end has been developed using the method of images. Presented in this research is the development of this three-dimensional method of images analysis for a rectangular duct. Using this analysis, a model of the impulse response of the acoustic channel is constructed. Also presented in this work is the actual impulse response collected during field experimentation in the south turning basin of Port Everglades in Fort Lauderdale, Florida. The results demonstrate that the impulse response is modeled with a relative echo magnitude error of 1.62 dB at worst, and a relative echo location error varying between 0% and 4% when averaged across multiple measurements and sensor locations.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00012557
- Subject Headings
- Underwater acoustics--Measurement, Wave motion, Theory of, Wave equation--Numerical solutions, Sound-waves--Transmission--Mathematical models
- Format
- Document (PDF)
