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Full-Text Articles in Physical Sciences and Mathematics
Sidescan Sonar Image Enchancement Using A Decomposition Based On Orthogonal Functions. Applications With Chebyshev Polynomials, Pierre Cervenka, Christian De Moustier
Sidescan Sonar Image Enchancement Using A Decomposition Based On Orthogonal Functions. Applications With Chebyshev Polynomials, Pierre Cervenka, Christian De Moustier
Center for Coastal and Ocean Mapping
A method is presented to remove from sidescan sonar images of the seafloor, artifacts that are clearly unrelated to the backscattering properties of the seafloor. A spectral analysis performed on a ping by ping basis proved to be well suited to the problem. The technique relies on a decomposition using Chebyshev polynomials. This stochastic method does not require a priori knowledge of deterministic parameters. It deals with the low spatial frequency components of the image whose wavelengths are not very small compared to the swath width. Applications to sidescan sonar images obtained with the SeaMARC LI system are presented.
Angular Dependence Of 12-Khz Seafloor Acoustic Backscatter, Christian De Moustier, Dimitri Alexandrou
Angular Dependence Of 12-Khz Seafloor Acoustic Backscatter, Christian De Moustier, Dimitri Alexandrou
Center for Coastal and Ocean Mapping
The angular dependence of seafloor acoustic backscatter,measured with a 12‐kHz multi narrow‐beam echo‐sounder at two sites in the central North Pacific with water depths of 1500 and 3100 m, respectively, has been determined for incidence angles between 0° and 20°. The acoustic data consist of quadrature samples of the beamformed echoes received on each of the 16 2.66° beams of a Sea Beam echo‐sounder. These data are subjected to adaptive noise cancelling for sidelobe interference rejection, and the centroid of each echo is determined. After corrections for the ship’s roll and raybending effects through the water column, the angles of …
Grape Density Records And Density Cyclicity, Eystein Jansen, Larry A. Mayer, Shipboard Scientific Party
Grape Density Records And Density Cyclicity, Eystein Jansen, Larry A. Mayer, Shipboard Scientific Party
Affiliate Scholarship
No abstract provided.
High-Resolution, Whole-Core Magnetic Susceptibility Data From Leg 130, Ontong Java Plateau, John A. Tarduno, Larry A. Mayer, Robert Musgrave
High-Resolution, Whole-Core Magnetic Susceptibility Data From Leg 130, Ontong Java Plateau, John A. Tarduno, Larry A. Mayer, Robert Musgrave
Affiliate Scholarship
High-resolution, whole-core magnetic susceptibility data, recorded at 3-cm intervals, were obtained for advanced hydraulic piston (APC) cores at Sites 805, 806, and 807 of Leg 130 on the Ontong Java Plateau. In this initial report, we present a preliminary evaluation of these data for their use in core correlations and paleoclimatic studies. The data allow detailed intrasite correlations between the offset APC cores and provide a means for intersite correlations of Pleistocene sediments. Variations in magnetic susceptibility values probably mirror variations in terrestrial influx and may act as proxy indicators of climate. Highly coherent cyclicity, representing Milankovitch orbital frequencies, is …
Ontong Java Plateau, Leg 130: Synopsis Of Major Drilling Results, W. H. Berger, Loren W. Kroenke, Larry A. Mayer, Shipboard Scientific Party
Ontong Java Plateau, Leg 130: Synopsis Of Major Drilling Results, W. H. Berger, Loren W. Kroenke, Larry A. Mayer, Shipboard Scientific Party
Affiliate Scholarship
Sixteen holes were drilled at five sites on the northeastern flank of Ontong Java Plateau during Leg 130 (Sites 803 through 807). All of these sites are near the equator, but are at different depths (803: 02°26.0'N, 3410 m; 804: 01°00.3'N, 3861 m; 805: 01°13.7'N, 3188 m; 806: 00°19.1'N, 2520 m; and 807: 03°36.4'N, 2805 m). One of our goals was to obtain a depth transect of Neogene carbonate deposition for reconstructing the history of ocean climate, chemistry, and productivity, and for understanding the origin of acoustic reflectors. Another goal was to achieve considerable penetration into basement for elucidating the …