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The location of the hydrophones on a towed underwater acoustic array as a function of time (array element localization) is needed for signal processing. Methods to perform this localization using least squares polynomial fitting to data from depth sensors, heading sensors, and sensors detecting a ping from a single source are discussed. Arc distance along the array is used as the independent parameter so that all solutions are constrained to be space curves. Examples of application to real data are presented, and techniques to discriminate against bad sensor data are discussed 相似文献
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A dredged material disposal operation was monitored at a location in Lake Erie, 8 km offshore at Ashtabula, Ohio, in 1975.
Approximately 200 sediment cores were collected from 12 experimental and 4 control locations before and after dredging and
analyzed for the grain-size distribution and related heavy-metal content.
The dredged sediments were similar to those from the lake bottom at the disposal and control sites. Because of this similarity,
it was extremely difficult to distinguish between the dredged material and the lake bottom sediments without tagging the material
with dyes or radioactive isotopes. A sequence consisting of a linear discriminant analysis followed by a univariate and multivariate
analysis of variance was successfully applied to discriminate between the dredged and the original lake sediments. Results
indicate that 4 months after the disposal operation some stations had returned to predisposal conditions, a probable result
of currents stripping dredged material off the lake bottom. The analysis of variance indicated that the clay-size fraction
was responsible for initial changes in the grain-size distribution. Storm induced scouring caused an eventual return of the
grain-size distribution to predisposal conditions.
In support of this observation, the concentrations of iron and zinc, which were statistically correlated to the clay size
fraction, also exhibited the same trends. 相似文献
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