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Full-Text Articles in Engineering
Seabed Observations At The New England Mud Patch: Reflection And Scattering Measurements And Direct Geoacoustic Information, Charles W. Holland, Chad M. Smith, Zackary Lowe, Jim Dorminy
Seabed Observations At The New England Mud Patch: Reflection And Scattering Measurements And Direct Geoacoustic Information, Charles W. Holland, Chad M. Smith, Zackary Lowe, Jim Dorminy
Electrical and Computer Engineering Faculty Publications and Presentations
Seabed reflection and scattering measurements were conducted at the New England Mud Patch to better understand the acoustic properties of fine-grained (muddy) sediments. The measurement philosophy and the measurements themselves are summarized. In addition, geoacoustic information accessed directly from the data in the time and frequency domains is presented. The main result is the existence of an angle of intromission. This observation proves that the mud sound speed is less than that of the water and yields a sediment sound speed ratio 0.9865 with outer bounds {0.985 0.989}. Another result is the observation of strong scattered arrivals from within the …
Sound Speed Gradients In Mud, Charles W. Holland
Sound Speed Gradients In Mud, Charles W. Holland
Electrical and Computer Engineering Faculty Publications and Presentations
Various methods have been used to estimate sound speed profiles in mud at the New England Mud Patch. Some of these methods show large sound speed gradients of order 10 s−1. New measurements of the seabed reflection coefficient exhibit an angle of intromission over three octaves in frequency; these data constrain the range of possible sound speed gradient values. The data indicate that sound speed gradients must be quite weak, i.e., much smaller than |10 s−1|. This conclusion is supported by core data which indicate nearly constant porosity in most of the mud layer.
On Compressional Wave Attenuation In Muddy Marine Sediments, Charles W. Holland, Stan E. Dosso
On Compressional Wave Attenuation In Muddy Marine Sediments, Charles W. Holland, Stan E. Dosso
Electrical and Computer Engineering Faculty Publications and Presentations
A method for measuring in situ compressional wave attenuation exploiting the spectral decay of reflection coefficient Bragg resonances is applied to fine-grained sediments in the New England Mud Patch. Measurements of layer-averaged attenuation in a 10.3 m mud layer yield 0.04 {0.03, 0.055} dB/m/kHz (braces indicate outer bounds); the attenuation is twice as large at a site with 3.2 m mud thickness. It is shown that both results are heavily influenced by a ∼1 m sand-mud transition interval created by geological and biological processes that mix sand (at the base of the mud) into the mud. Informed by the observations, …