Current Search: Sediment (x)
Pages
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Title
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Morphodynamic evolution of a newly formed tidal inlet.
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Creator
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Liu, James T., Stauble, Donald K., Giese, Graham S., Aubrey, David G., Harbor Branch Oceanographic Institute
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Date Issued
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1993
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PURL
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http://purl.flvc.org/FCLA/DT/3172977
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Subject Headings
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Coast changes, Tides, Inlets, Sediment transport, Lagoons
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Format
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Document (PDF)
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Title
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Effects of physical gradients on the production dynamics of sediment-associated algae.
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Creator
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Davis, M. W., McIntire, C. D., Harbor Branch Oceanographic Institute
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Date Issued
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1983
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PURL
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http://purl.flvc.org/FCLA/DT/3350843
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Subject Headings
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Biomass, Seagrasses, Estuaries, Marine sediments, Algae, Diatoms
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Format
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Document (PDF)
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Title
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The effect of hyperpycnal water on tidal exchange.
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Creator
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Smith, Ned P.
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Date Issued
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1996
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PURL
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http://purl.flvc.org/FCLA/DT/3172981
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Subject Headings
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Hydrology, Tides, Sediment transport, Salinity, Temperature
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Format
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Document (PDF)
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Title
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Wind domination of residual tidal transport in a coastal lagoon.
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Creator
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Smith, Ned P.
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Date Issued
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1990
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PURL
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http://purl.flvc.org/FCLA/DT/3174018
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Subject Headings
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Lagoons, Coasts, Tidal currents, Sediment transport, Wind
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Format
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Document (PDF)
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Title
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Diel variations of dissolved ammonia and phosphate in estaurine sediment pore water.
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Creator
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Montgomery, John R., Zimmermann, Carl F., Peterson, Gary N., Price, Mary T., Harbor Branch Oceanographic Institute
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Date Issued
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1983
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PURL
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http://purl.flvc.org/fau/fd/FA00007476
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Subject Headings
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Estuarine sediments, Pore water, Ammonia, Phosphates
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Format
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Document (PDF)
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Title
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Model experiments for the acoustic field in a water column which includes the effects of shear in marine sediments.
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Creator
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Hundley, Allen John., Florida Atlantic University, Glegg, Stewart A. L.
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Abstract/Description
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A scaled, horizontally stratified shallow water marine acoustic model is constructed for the purpose of investigating the sound field resulting from long range propagation. The characteristics of this sound field in the water column are strongly dependent upon properties of the surficial sediment. One effect is the conversion from compressional waves in the water column to shear waves in the sediment at grazing angles less than the critical. To model a shallow marine environment, concrete is...
Show moreA scaled, horizontally stratified shallow water marine acoustic model is constructed for the purpose of investigating the sound field resulting from long range propagation. The characteristics of this sound field in the water column are strongly dependent upon properties of the surficial sediment. One effect is the conversion from compressional waves in the water column to shear waves in the sediment at grazing angles less than the critical. To model a shallow marine environment, concrete is used as a substrate rock and laminating epoxy is used to model a surficial sediment. Preliminary tests of the effects of the model's environment are performed, and the range dependent sound field as a function of depth is measured for several CW frequencies. These sound field profiles are compared with an approximate predictive theory, and with a numerical solution which treats the sediment properties exactly.
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Date Issued
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1990
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PURL
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http://purl.flvc.org/fcla/dt/14618
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Subject Headings
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Underwater acoustics, Marine sediments--Acoustic properties
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Format
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Document (PDF)
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Title
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Nitrate partitioning between water and sediments.
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Creator
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Kari, Ramanaprasad., Florida Atlantic University, Scarlatos, Panagiotis (Pete) D., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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A complete understanding of nitrate partitioning between water and sediments is absolutely necessary to quantify eutrophication and other harmful effects of nitrate addition to a lake. The bottom sediments can act both as source and sink for nitrates. Turbulent conditions induced by wind forces cause sediments to suspend in the water column. During suspension sediments adsorb/release nitrates and other contaminants into the ambient water. This study investigated the effects of temperature,...
Show moreA complete understanding of nitrate partitioning between water and sediments is absolutely necessary to quantify eutrophication and other harmful effects of nitrate addition to a lake. The bottom sediments can act both as source and sink for nitrates. Turbulent conditions induced by wind forces cause sediments to suspend in the water column. During suspension sediments adsorb/release nitrates and other contaminants into the ambient water. This study investigated the effects of temperature, sediment and nitrate concentration on the exchange and partitioning of nitrates between water and sediments. The Langmuir adsorption model was used to quantify the adsorption/desorption processes. A decrease in the value of partition coefficient with increase in sediment concentration was observed. The laboratory experiments revealed that an increase in temperature of the water column favored the adsorption of nitrates by the bottom sediments. The nitrate diffusion coefficients were estimated by utilizing Fick's second law of diffusion. Sediment concentration profiles were strongly dependant on the oscillating-grid induced turbulence effects.
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Date Issued
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1993
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PURL
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http://purl.flvc.org/fcla/dt/14946
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Subject Headings
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Nitrates, Water--Pollution, Sediments, Suspended
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Format
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Document (PDF)
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Title
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Impact of noise on seafloor property estimation using Biot model parameters obtained through an inversion of chirp sonar data.
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Creator
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Munro, Lachlan I., Florida Atlantic University, Schock, Steven G., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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This thesis describes the development and testing of an inversion method, based on the Biot-Stoll acoustic wave propagation model, for estimating sediments properties from acoustic reflection measurements of the seabed. The Biot-Stoll model is a physics-based model which describes the propagation of compressional and shear waves through porous media. Given the physical sediment properties of the seabed, the pressure reflection coefficient of the seabed is calculated using the Biot-Stoll model...
Show moreThis thesis describes the development and testing of an inversion method, based on the Biot-Stoll acoustic wave propagation model, for estimating sediments properties from acoustic reflection measurements of the seabed. The Biot-Stoll model is a physics-based model which describes the propagation of compressional and shear waves through porous media. Given the physical sediment properties of the seabed, the pressure reflection coefficient of the seabed is calculated using the Biot-Stoll model. The proposed inversion procedure varies sediment properties until a least squares fit is obtained between the output of the model and the measured reflection coefficient. Random errors are introduced into the reflection coefficient measurement to determine the effect of measurement error in the estimation of seabed properties such as permeability, porosity, mean grain diameter, and sediment type.
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Date Issued
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2003
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PURL
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http://purl.flvc.org/fcla/dt/13084
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Subject Headings
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Underwater acoustics, Marine sediments--Acoustic properties
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Format
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Document (PDF)
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Title
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POLYCHAETE-SEDIMENT RELATIONSHIPS ALONG A SUBTIDAL TRANSECT OFF SOUTHEASTERN FLORIDA.
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Creator
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WAINRIGHT, SAM CHAPMAN, Florida Atlantic University
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Abstract/Description
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The benthic polychaete community and its associated sedimentary environment were examined in February and August, 1978, at five stations ranging in depth from 2.3 to 19.8 m off Highland Beach, Florida. A total of 176 species were collected; the numbers of species and individuals increased from the nearshore station to the station farthest from shore. These increases are thought to be a result of decreased wave-induced turbulence and increased food supply in deeper waters. Motile infaunal...
Show moreThe benthic polychaete community and its associated sedimentary environment were examined in February and August, 1978, at five stations ranging in depth from 2.3 to 19.8 m off Highland Beach, Florida. A total of 176 species were collected; the numbers of species and individuals increased from the nearshore station to the station farthest from shore. These increases are thought to be a result of decreased wave-induced turbulence and increased food supply in deeper waters. Motile infaunal feeders comprised the majority of the community at the shallower stations (especially in winter) while discretely motile and sessile surface feeders dominated in deeper water. Dominant species at each station showed little functional overlap, suggesting that resource partitioning was occurring. Sediment parameters, although not as important as depth and turbulence in regulating community structure, showed significant correlations with biological parameters.
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Date Issued
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1983
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PURL
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http://purl.flvc.org/fcla/dt/14144
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Subject Headings
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Polychaeta--Florida--Highland Beach, Marine sediments
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Format
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Document (PDF)
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Title
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Validation of numerical modelling for long range acoustic propagation.
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Creator
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Riley, Joseph M., Florida Atlantic University, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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Laboratory scale measurements were conducted to validate numerical prediction models used to predict the acoustic field in a shallow water ocean environment. Experimental measurements were conducted in a range independent environment which included the effects of shear in marine sediments and in a depth varying range dependent environment. Good agreement between the experimental measurements and the numerical prediction codes were obtained using optimized values for the input parameters of...
Show moreLaboratory scale measurements were conducted to validate numerical prediction models used to predict the acoustic field in a shallow water ocean environment. Experimental measurements were conducted in a range independent environment which included the effects of shear in marine sediments and in a depth varying range dependent environment. Good agreement between the experimental measurements and the numerical prediction codes were obtained using optimized values for the input parameters of the environmental model. In comparing experimental measurements to the numerical prediction codes it became apparent that the codes were very sensitive to the input parameters describing the bottom boundary of the ocean waveguide.
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Date Issued
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1992
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PURL
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http://purl.flvc.org/fcla/dt/14819
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Subject Headings
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Acoustical engineering, Underwater acoustics, Marine sediments
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Format
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Document (PDF)
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Title
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APPLICATION OF A MICROPROCESSOR TO ACOUSTIC DATA SAMPLING AND MANAGEMENT TASKS (AS APPLIED TO MANGANESE NODULE MINING).
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Creator
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MURPHY, DAVID PAUL, JR., Florida Atlantic University, Davidson, J. Blaine, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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Methods of collecting information about the deep ocean sediments are considered. A compact, flexible data collection and management system based on microprocessor technology is developed. The hardware of the system is detailed and a typical software operating system is presented which controls sensor operations, stores temporary data and communicates with a shipboard computer system.
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Date Issued
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1979
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PURL
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http://purl.flvc.org/fcla/dt/13987
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Subject Headings
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Microprocessors, Marine sediments--Sampling, Manganese nodules
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Format
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Document (PDF)
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Title
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A volume scattering model for sediment classification through acoustic means.
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Creator
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Jenkins, Michael Gerard., Florida Atlantic University, LeBlanc, Lester R.
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Abstract/Description
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A simple model is developed to evaluate the acoustic scattering environment of sediments based on the envelope function of digital sub-bottom sonar data. Scattering pressure and intensity histograms are produced from model results. These histograms are compared to the theoretical distributions expected for scattering event pressure and intensity. Sediment composition is inferred from the determined acoustic scattering environment. The model has been applied to X-Star digital sub-bottom data...
Show moreA simple model is developed to evaluate the acoustic scattering environment of sediments based on the envelope function of digital sub-bottom sonar data. Scattering pressure and intensity histograms are produced from model results. These histograms are compared to the theoretical distributions expected for scattering event pressure and intensity. Sediment composition is inferred from the determined acoustic scattering environment. The model has been applied to X-Star digital sub-bottom data taken in the vicinity of St. John's Harbor, New Brunswick. Model results are compared to ground truth (Borehole logs) taken within the survey area. This comparison indicates general trends within the sediment scattering environment which may be linked to sediment composition. Distinct differences in model results were noted over areas of differing sediment types.
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Date Issued
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1993
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PURL
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http://purl.flvc.org/fcla/dt/14945
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Subject Headings
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Sedimentation analysis, Underwater acoustics, Sound--Reverberation
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Format
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Document (PDF)
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Title
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Event-driven Nearshore Sediment Transport and Morphodynamics of a Beach in Boca Raton, Florida.
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Creator
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Priddy, Michael S., Briggs, Tiffany Roberts, Florida Atlantic University, Department of Geosciences, Charles E. Schmidt College of Science
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Abstract/Description
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Tropical storms and mid-latitude cyclones are major drivers of coastal change and damage in coastal communities. Beaches act as a first line of defense against storms, as well as provide recreation, contribute to the economy, and serve as ecological habitat for coastal flora and fauna. Throughout the year, meteorological event-driven increases in wave energy result in higher amounts of sediment transport that cause rapid coastal zone morphology alterations and threaten these beach functions....
Show moreTropical storms and mid-latitude cyclones are major drivers of coastal change and damage in coastal communities. Beaches act as a first line of defense against storms, as well as provide recreation, contribute to the economy, and serve as ecological habitat for coastal flora and fauna. Throughout the year, meteorological event-driven increases in wave energy result in higher amounts of sediment transport that cause rapid coastal zone morphology alterations and threaten these beach functions. This study uses streamer traps to evaluate cohesionless sediment dynamics in the surf zone and storm-induced morphology change in Boca Raton, Florida. The quantitative and sedimentological characteristics of sediment collected in the bottom streamer trap bins was larger grains with a higher capture weight near the seabed compared to sediment captured in the middle and upper streamer trap bins during both the cold front and the tropical storm. A greater quantity of sediment was captured in transport due to the tropical storm compared to the cold front. Morphology change observed as a result of the cold front included berm erosion, swash zone and foreshore accretion, and erosion beyond the -1.0m contour elevation. Analysis of the morphology observed post-tropical storm included berm accretion, and swash zone and foreshore erosion that continued seaward to the end of the profile. Dean number calculations using pre-cold front sediments and wave parameters predicted erosion, and the post-cold front BMAP measurements confirmed this prediction. Dean number calculations using pre-tropical storm sediments and wave parameters predicted accretion and the post-tropical storm BMAP measurements invalidated this prediction at all capture locations, although above the 1.0m contour the berm did exhibit accretion. Results of this study aim to quantify granulometric differences in event-driven sediment transport in Boca Raton, FL for improved prediction capabilities. Given the current trajectory of climate change, sea-level rise, and increased storm intensity, better understanding the morphological impact of different classes of storms is necessary to ensure and improve coastal resiliency and management.
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Date Issued
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2022
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PURL
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http://purl.flvc.org/fau/fd/FA00014005
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Subject Headings
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Sediment transport, Boca Raton (Fla.), Geomorphology, Beaches
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Format
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Document (PDF)
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Title
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MORPHOLOGIC CHANGES AND SEDIMENTOLOGICAL SIGNATURES RESULTING FROM HURRICANE IAN IN SOUTHWEST FLORIDA.
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Creator
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McCormick, W. Mathew, Roberts, Tiffany Briggs, Florida Atlantic University, Department of Geosciences, Charles E. Schmidt College of Science
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Abstract/Description
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On September 28, 2022, Hurricane Ian, a large Category 4 hurricane, caused catastrophic damage and significant morphologic change along the southwest Florida barrier islands. This study evaluates the morphologic changes and sedimentological signatures of deposits resulting from Hurricane Ian through a combination of sediment cores, RTK-GPS beach profiles, and pre- and post-storm digital elevation models. During the storm, bidirectional sediment transport processes occurred along both...
Show moreOn September 28, 2022, Hurricane Ian, a large Category 4 hurricane, caused catastrophic damage and significant morphologic change along the southwest Florida barrier islands. This study evaluates the morphologic changes and sedimentological signatures of deposits resulting from Hurricane Ian through a combination of sediment cores, RTK-GPS beach profiles, and pre- and post-storm digital elevation models. During the storm, bidirectional sediment transport processes occurred along both developed and undeveloped shorelines, producing extensive washover deposits and ebb scour channels from the flood and ebb surges, respectively. Washover deposits contained interbedded sand and shell fragments with vertical grain size distributions dependent on position relative to the dune crest. Both washover deposits and ebb scour channels formed along dune crest elevational lows and were limited by dense vegetation and anthropogenic structures. Results from this study can be used to better constrain morphologic changes resulting from bidirectional sediment transport processes during large magnitude storm events.
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Date Issued
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2024
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PURL
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http://purl.flvc.org/fau/fd/FA00014383
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Subject Headings
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Hurricane Ian, Geomorphology--Florida, Coastal sediments
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Format
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Document (PDF)
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Title
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Investigating a Cryptic Iron-Nitrogen Cycle in Lake Okeechobee Sediments`.
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Creator
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Silvera, Owen, Beckler, Jordon, Florida Atlantic University, Department of Marine Science and Oceanography, Charles E. Schmidt College of Science
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Abstract/Description
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The overall objective was to elucidate the effect of iron (Fe) on nitrogen (N) diagenesis in Lake Okeechobee. Somewhat counterintuitively, sediment ammonium (NH+4) inventories decreased during algal growth as dissolved organic nitrogen (DON) inventories increased. Whole core incubations were staged for denitrification experiments using isotopic N tracer. Core incubations showed the percentage of sediment N removal increase between summer (25 ± 21 %) and winter (39 ± 13 %). The amendment of...
Show moreThe overall objective was to elucidate the effect of iron (Fe) on nitrogen (N) diagenesis in Lake Okeechobee. Somewhat counterintuitively, sediment ammonium (NH+4) inventories decreased during algal growth as dissolved organic nitrogen (DON) inventories increased. Whole core incubations were staged for denitrification experiments using isotopic N tracer. Core incubations showed the percentage of sediment N removal increase between summer (25 ± 21 %) and winter (39 ± 13 %). The amendment of Fe2+ enhanced this seasonal effect likely via dissimilatory nitrate reduction to ammonium (DNRA). The isotopic signature of N2 flux also suggested an additional, sedimentary, N2 source via Fe coupled anaerobic oxidation of ammonium (feammox). Sediment slurry incubations supported the occurrence of both DNRA and feammox, showing first that nitrate (NO3−) was converted to NH4+ via DNRA, which contributed 23-26% of overall NO3− reduction. Fe amendment in slurries similarly stimulated the feammox process. However, aged Fe minerals accumulated linearly with N bound to Fe (Fe-N) in a subseasonal sediment time series, suggesting Fe-organic matter aggregation may lower the sediment NH4+ equilibrium concentration and benthic flux.
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Date Issued
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2024
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PURL
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http://purl.flvc.org/fau/fd/FA00014486
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Subject Headings
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Okeechobee, Lake (Fla.), Diagenesis, Sediments (Geology), Biogeochemistry
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Format
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Document (PDF)
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Title
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Links between iron input and opal deposition in the Pleistocene equatorial Pacific Ocean.
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Creator
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Murray, Richard W., Leinen, M. S., Knowlton, C. W., Harbor Branch Oceanographic Institute
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Date Issued
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2012
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PURL
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http://purl.flvc.org/FCLA/DT/3351986
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Subject Headings
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Pleistocene Epoch, Iron, Opals, Marine sediments--Pacific Ocean, Sedimentation and deposition
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Format
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Document (PDF)
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Title
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Deep-Water Biogenic Sediment off the Coast of Florida.
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Creator
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Zuccarelli, Claudio L., Oleinik, Anton E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
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Abstract/Description
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Biogenic “oozes” are pelagic sediments that are composed of > 30% carbonate microfossils and are estimated to cover about 50% of the ocean floor, which accounts for about 67% of calcium carbonate in oceanic surface sediments worldwide. These deposits exhibit diverse assemblages of planktonic microfossils and contribute significantly to the overall sediment supply and function of Florida’s deep-water regions. However, the composition and distribution of biogenic sediment deposits along these...
Show moreBiogenic “oozes” are pelagic sediments that are composed of > 30% carbonate microfossils and are estimated to cover about 50% of the ocean floor, which accounts for about 67% of calcium carbonate in oceanic surface sediments worldwide. These deposits exhibit diverse assemblages of planktonic microfossils and contribute significantly to the overall sediment supply and function of Florida’s deep-water regions. However, the composition and distribution of biogenic sediment deposits along these regions remains poorly documented. Seafloor surface sediments have been collected in situ via Johnson- Sea-Link I submersible along four of Florida’s deep-water regions during a joint research cruise between Harbor Branch Oceanographic Institute (HBOI) and Florida Atlantic University (FAU). Sedimentological analyses of the taxonomy, species diversity, and sedimentation dynamics reveal a complex interconnected development system of Florida’s deep-water habitats. Results disclose characteristic microfossil assemblages of planktonic foraminiferal ooze off the South West Florida Shelf, a foraminiferal-pteropod ooze through the Straits of Florida, and pteropod ooze deposits off Florida’s east coast. The distribution of the biogenic ooze deposits is attributed to factors such as oceanographic surface production, surface and bottom currents, off-bank transport, and deep-water sediment drifts. The application of micropaleontology, sedimentology, and oceanography facilitate in characterizing the sediment supply to Florida’s deep-water regions.
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Date Issued
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2017
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PURL
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http://purl.flvc.org/fau/fd/FA00004857
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Subject Headings
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Marine sediments., Sediment transport., Deep-sea ecology., Ecosystem management., Micropaleontology
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Format
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Document (PDF)
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Title
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EVALUATION OF LOCAL OFFSHORE SEDIMENTS FOR COASTAL RESTORATION PROJECTS IN PALM BEACH COUNTY, FL, USA.
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Creator
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Palaparthi, Jyothirmayi, Briggs, Tiffany Roberts, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
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Abstract/Description
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Open-coast beach-dune environments are vulnerable to erosion, such as from storms or interruption of littoral drift. Although protected from event-driven wave energy, backbarrier shorelines are also susceptible to erosion, due to tidal currents and boat wakes. A common response to mitigate erosion is to place sediment and restore the environment. For placement on beaches, a significant effort has been made to identify offshore resources available; however, offshore resources have seldom been...
Show moreOpen-coast beach-dune environments are vulnerable to erosion, such as from storms or interruption of littoral drift. Although protected from event-driven wave energy, backbarrier shorelines are also susceptible to erosion, due to tidal currents and boat wakes. A common response to mitigate erosion is to place sediment and restore the environment. For placement on beaches, a significant effort has been made to identify offshore resources available; however, offshore resources have seldom been considered for dune or backbarrier shoreline restoration. This study evaluates the geotechnical sediment properties of offshore sediments in proven borrow areas for beach nourishment and reclassifies them for placement in dunes and along the backbarrier in Palm Beach County, Florida. Two different methods calculate volume of offshore resources available for dune or backbarrier projects, including numerical calculations and interpolation of volume through SURFER. Because existing proven borrow areas are delineated for beach nourishment, less volume of sediment available in these areas for other coastal environments. The results of this study suggest that identifying offshore sediment sources for lower-energy environments would not adversely impact sediment needed for beach nourishment. As coastal environments are increasingly threatened by climate change and sea level rise, sediment resources become scarcer, the need to efficiently and effectively use sediments will be of utmost importance for scientists, engineers, and managers in their efforts to protect coastal habitat and communities.
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Date Issued
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2019
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PURL
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http://purl.flvc.org/fau/fd/FA00013337
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Subject Headings
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Sedimentation and deposition, Coastal erosion, Palm Beach County (Fla ), Sediments (Geology)--Analysis, Dunes, Coastal restoration
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Format
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Document (PDF)
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Title
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Classification of marine sediments using a fuzzy logic impedance inversion model.
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Creator
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DeBruin, Darryl L., Florida Atlantic University, LeBlanc, Lester R., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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In this dissertation, a fuzzy logic impedance inversion model is developed to classify marine sediments. Expert knowledge and fuzzy decision making constrain the inversion procedures to the resolving ability of the transmitted. The model is validated by comparing the estimated impedance profile with the measured impedance profile. A coherent surface scattering and incoherent volume scattering model are incorporated into a single geoacoustic scattering model that is applied to acoustic...
Show moreIn this dissertation, a fuzzy logic impedance inversion model is developed to classify marine sediments. Expert knowledge and fuzzy decision making constrain the inversion procedures to the resolving ability of the transmitted. The model is validated by comparing the estimated impedance profile with the measured impedance profile. A coherent surface scattering and incoherent volume scattering model are incorporated into a single geoacoustic scattering model that is applied to acoustic subbottom measurements. The reflected signal is modeled as the convolution of the transmitted processed wavelet and the impulse response of the sea bottom. The impedance of the acoustic return is inverted at the layer interfaces and the volume scattering strength is measured between layer interfaces. The model is applied to acoustic subbottom measurements obtained by an X-STAR subbottom profiler sonar system. The inversion techniques are developed for a 2-10 kHz 20 msec swept FM pulse. A fuzzy logic layer tracking procedure identifies the coherent surface scattering layer interfaces in a subbottom profile image. The peak amplitudes and locations are used as fuzzy inputs in the layer tracking rule base. The rule base determines which peak is assigned to the layer when two peaks compete for assignment or which layer is assigned to the peak when two layers compete for assignment. The fuzzy event detection algorithm estimates the impulse response of the acoustic return by complex least squares fitting parts of the transmitted wavelet with sections of the acoustic return. Reflectors are iteratively identified and removed from the return and the residual return is reprocessed. The detection procedure is constrained by the resolving ability of the matching signals and the peak envelope shape of the acoustic return. A genetic algorithm allows up to five low error reflector estimates to be processed until converging on the correct estimated impulse response (the tree branch whose summed error is minimized). The impedance is correlated with sediment bulk density by empirical relation. Experimental results validate that the fuzzy logic impedance inversion model reliably estimates the impedance of the sea bottom. The estimated impedance profiles of fifty acoustic returns are averaged and compared with measured impedance values.
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Date Issued
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1995
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PURL
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http://purl.flvc.org/fcla/dt/12415
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Subject Headings
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Fuzzy logic, Marine sediments, Acoustic impedance, Marine sediments--Acoustic properties
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Format
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Document (PDF)
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Title
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The normal incidence reflection coefficient of a sandy seabed as a function of frequency.
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Creator
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Arizzi, Ernest Allen., Florida Atlantic University, Schock, Steven G.
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Abstract/Description
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A thesis investigates the measured and theoretical pressure reflection coefficients of the seabed at normal incidence. The theoretical reflection coefficient is calculated using a physics-based model developed by Maurice Biot. The model describes sound propagation in saturated porous media and interrelationships between the acoustic properties of the media and the physical properties of the pore fluid and the porous solid. Stoll modified the Biot model for the case of ocean sediments and...
Show moreA thesis investigates the measured and theoretical pressure reflection coefficients of the seabed at normal incidence. The theoretical reflection coefficient is calculated using a physics-based model developed by Maurice Biot. The model describes sound propagation in saturated porous media and interrelationships between the acoustic properties of the media and the physical properties of the pore fluid and the porous solid. Stoll modified the Biot model for the case of ocean sediments and developed an expression for calculating the reflection coefficient as a function of frequency. This thesis tests the model by comparing the reflection coefficient measured with chirp sonar to the reflection coefficient calculated using the Biot model. An experiment was conducted off Fort Walton Beach, Florida where chirp sonar transmitted FM pulses at normal incidence to a sandy seabed. Sediment properties measured during SAX-99 are used to calculate the theoretical reflection coefficient using the Biot-Stoll model. The agreement of the measured reflection coefficients with the theoretical calculations over the band of 1500 to 16000 Hz varies as much as 70%. The plotted results show a reduction of the reflection coefficient with frequency but the large deviations from the trend prevent any further conclusions.
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Date Issued
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2004
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PURL
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http://purl.flvc.org/fcla/dt/13191
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Subject Headings
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Marine sediments--Acoustic properties, Underwater acoustics--Measurement, Sedimentation analysis
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Format
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Document (PDF)
Pages