摘要 :
Echoes reflected from the sea floor hold a great deal of information beyond whatis visible in simple time series of spectra. In addition to reflections from different boundary layers, structures contained in these layers will be e...
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Echoes reflected from the sea floor hold a great deal of information beyond whatis visible in simple time series of spectra. In addition to reflections from different boundary layers, structures contained in these layers will be excited by energy from the incident pulse and may reradiate this energy. This reradiated energy will contain information about the physical nature of the structure and surrounding media. This work looks at application of time scale signal expansions to extracting such information from fathometer echoes.
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摘要 :
A need exists in both the civilian and military communities for an automatedseafloor classification system that can remotely and accurately estimate and map sediment properties for a number of seafloor engineering applications and...
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A need exists in both the civilian and military communities for an automatedseafloor classification system that can remotely and accurately estimate and map sediment properties for a number of seafloor engineering applications and for input to acoustic propagation prediction models. Over the past several years the Naval Research Laboratory (NRL) has been developing a normal incidence, narrow beamwidth, high resolution seismic system that has the capability to accurately predict, in near real-time, acoustic impedance, sediment type and a number of selected geotechnical properties of the upper several meters of the seafloor while in an underway survey mode, Lambert. The system is designated the Acoustic Seafloor Classification System (ASCS) and is technology based on the Echo-strength Measuring System (EMS) developed in the early 1980's by Honeywell ELAC of Kiel, Germany. A detailed description of this system can be found in Lambert and Fielder.
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摘要 :
Induced excess pore water pressures resulting from the insertion of piezometerprobes of 8-mm (0.31-in.) diameter and a simulated waste canister of 102-mm (4.0-in.) diameter and the dissipation of these excess pressures were measur...
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Induced excess pore water pressures resulting from the insertion of piezometerprobes of 8-mm (0.31-in.) diameter and a simulated waste canister of 102-mm (4.0-in.) diameter and the dissipation of these excess pressures were measured during deep-ocean component tests of the In Situ Heat Transfer Experiment (ISHTE). The sediment at the Pacific test site 1100 km north of Oahu, Hawaii, is an illitic clay. Insertion-induced excess pore pressures were found to agree well with those predicted by models. Several aspects of the induced excess pressure dissipation were evaluated including the effects of probe and heater diameter, distal excess pore pressure response, and the synergistic excess pore pressure response from multiple insertions. The dissipation of induced excess pressures measured at each piezometer is predicted well by theory. The same analytical models predict the excess pore pressure history measured at the piezometers in response to hte waste canister insertion. Present models were evaluated that predict insertion excess pressures and their dissipation rate at the probe surface and at distal, far field, points. Keywords: Piezometer; Pore pressure; Consolidation permeability; Ocean waste disposal. (RH)
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摘要 :
Sewage sludge in the New York Bight has been detected using a modified 200 KHz acoustic echo sounder. The three-dimensional distribution of suspended material and its rate of diffusion have been determined after digital processing...
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Sewage sludge in the New York Bight has been detected using a modified 200 KHz acoustic echo sounder. The three-dimensional distribution of suspended material and its rate of diffusion have been determined after digital processing of data. Increased biological activity is apparently associated with the presence of sewage sludge.
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