摘要 :
The physical mechanisms involved in the scattering of a linear acoustic field from a bubble, collection of bubbles, or other targets embedded in a fluid-saturated sediment are not well known. This research seeks to establish the u...
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The physical mechanisms involved in the scattering of a linear acoustic field from a bubble, collection of bubbles, or other targets embedded in a fluid-saturated sediment are not well known. This research seeks to establish the underlying physics particularly when the acoustic field excites resonances of the scatterer(s).
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摘要 :
This research investigated the scattering of an acoustic field from a bubble embedded in a saturated sediment. The primary objective was to establish the underlying physical mechanisms of resonance scattering near the breathing mo...
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This research investigated the scattering of an acoustic field from a bubble embedded in a saturated sediment. The primary objective was to establish the underlying physical mechanisms of resonance scattering near the breathing mode (or monopole) resonance.
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摘要 :
The long-term goal of this work is: (1) to develop a reverberation model for predicting the reverberation level and the echo-to-reverberation ratio in shallow water (SW) in a frequency band of 100-3000 Hz, and (2) to analyze the m...
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The long-term goal of this work is: (1) to develop a reverberation model for predicting the reverberation level and the echo-to-reverberation ratio in shallow water (SW) in a frequency band of 100-3000 Hz, and (2) to analyze the mechanisms of seabed scattering at low frequencies (LF). The objective is to set up a quality reverberation data base, to validate the SW reverberation model derived from the energy flux method, and to charaterize LF seabed scattering parameters.
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摘要 :
A model for acoustic scattering from the seabed was previously developed by Boyleand Chotiros. The model treats acoustic scattering as a sum of three independent processes, including scattering from the sediment interface, volume ...
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A model for acoustic scattering from the seabed was previously developed by Boyleand Chotiros. The model treats acoustic scattering as a sum of three independent processes, including scattering from the sediment interface, volume scattering from sediment grains, and volume scattering from trapped gas bubbles that might exist between grains. Recently, the gas bubble component of this model has been modified to allow for bistatic scattering and depth dependent sediment gas fractions. The theories behind these modifications are described, and in each case the character of the resulting model studied. jg.
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摘要 :
Normally incident sound pulses were used to investigate sediment types in the laboratory. Materials of five different grain sizes, ranging in diameter from 0.16 to 5.30mm, were used to find acoustic volume reverberation at three f...
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Normally incident sound pulses were used to investigate sediment types in the laboratory. Materials of five different grain sizes, ranging in diameter from 0.16 to 5.30mm, were used to find acoustic volume reverberation at three frequencies. An acoustic volume reverberation model was used to test the experimental data and to determine the scattering coefficients for the individual sediments. It was found that different sediments have different volume reverberations. From the slope of the trailing edge of the volume reverberation, the sediment type can be determined roughly. Different frequencies were used to find the relationship between volume reverberation and frequency, and the results showed that with increase in frequency the volume reverberation of the sediment will be decreased.
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摘要 :
Our long-term goal is to understand the processes that contribute to the establishment of the vertical structure of suspended sediment size-distribution and concentration with the bottom boundary layer acting as the principal source.
摘要 :
The goal of this work is to further develop and test models of volume scattering by utilizing the existing suite of instrumentation previously developed at APL- UW for the study of high-frequency acoustics. These models include pe...
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The goal of this work is to further develop and test models of volume scattering by utilizing the existing suite of instrumentation previously developed at APL- UW for the study of high-frequency acoustics. These models include perturbation models applied to scattering from the seafloor due to heterogeneities in the sediment properties, recently developed models by Dr. Ivakin, which model scattering from inclusions in the sediment such as shells and coarse grains, models which account for the transition layer observed during SAX99 which could have a strong effect on volume scattering at high frequencies, and perturbation theory for sound propagation through a varying poroelastic sediment.
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