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  • Other Sources  (7)
  • American Institute of Physics
  • 1995-1999  (4)
  • 1990-1994  (2)
  • 1980-1984  (1)
  • 1
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    Classification of heterogeneous seafloor topography through surface slope distributions (1991)
    American Institute of Physics
    In:  Journal of the Acoustical Society of America, 90 (4, Pt. 2). pp. 2255-2256.
    Details
    Publication Date: 2020-07-16
    Description: Seafloor topography is neither spatially homogeneous, nor does it obey Gaussian statistics; deviations from both of these assumptions are important from a geological and acoustic point of view. It has been found that the distribution of topographic slopes can be used as a primary tool for understanding the sources and extent of spatial heterogeneities and patterns on the seafloor. The covariance function has been widely used to characterize seafloor topography, but requires the assumption of Gaussian joint probability statistics to be valid. For heterogeneous topography characterized by large transient signals such as steep scarps and volcanoes, the covariance becomes dominated by the transients; in contrast the family slope distributions can still be used to derive stable descriptors for regions with large transient signals, as well as regions containing asymmetric features, and regions with only limited sampling. Knowledge of slopes is useful because a direct relation exists between the covariance and the slope distributions at different spatial scales. Studies of the slope distribution provide a means of identifying the presence of the non‐Gaussian elements in the topography, and flagging their spatial locations. The methods used here are demonstrated by applying them to three small patches of topography located within 20 km of each other in the Eastern Pacific. It is found that dominant azimuthal directions and dip angles differ widely between the patches. In addition, asymmetries in the cross‐sectional shapes of faulted abyssal hills are documented. [Work supported by ONR.]
    Type: Article , PeerReviewed
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  • 2
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    High‐frequency bottom backscattering: Roughness versus sediment volume scattering (1992)
    American Institute of Physics
    In:  Journal of the Acoustical Society of America, 92 (2). pp. 962-977.
    Details
    Publication Date: 2020-07-16
    Description: High‐frequency bottom acoustic and geoacoustic data from three well‐characterized sites of different bottom composition are compared with scattering models in order to clarify the roles played by interface roughness and sediment volume inhomogeneities. Model fits to backscattering data from two silty sites lead to the conclusion that scattering from volume inhomogeneities was primarily responsible for the observed backscattering. In contrast, measured bottom roughness was sufficient to explain the backscattering seen at a sandy site. Although the sandy site had directional ripples, the model and data agree in their lack of anisotropy.
    Type: Article , PeerReviewed
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  • 3
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    Dependence of multiple-attenuation techniques on the geological setting: A case study from offshore Taiwan (1999)
    American Institute of Physics
    In:  The Leading Edge, 18 (1). pp. 74-80.
    Details
    Publication Date: 2018-01-18
    Type: Article , NonPeerReviewed
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  • 4
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    3-D seismic discontinuity for faults and stratigraphic features: The coherence cube (1995)
    American Institute of Physics
    In:  The Leading Edge, 14 (10). pp. 1053-1058.
    Details
    Publication Date: 2016-07-26
    Description: Seismic data are usually acquired and processed for imaging reflections. This paper describes a method of processing seismic data for imaging discontinuities (e.g., faults and stratigraphic features). One application of this nontraditional process is a 3-D volume, or cube, of coherence coefficients within which faults are revealed as numerically separated surfaces. Figure 1 compares a traditional 3-D reflection amplitude time slice with the results of the new method. To our knowledge, this is the first published method of revealing fault surfaces within a 3-D volume for which no fault reflections have been recorded.
    Type: Article , PeerReviewed
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  • 5
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    Depth-pressure relationships in the oceans and seas (1998)
    American Institute of Physics
    In:  Journal of the Acoustical Society of America, 103 (3). pp. 1346-1352.
    Details
    Publication Date: 2020-07-16
    Description: Two sets of equations, covering all world oceans and seas, are presented to calculate pressure from depth for the computation of sound speed, and depth from pressure for use in ocean engineering. They are based on the algorithm of UNESCO 1983 [N. P. Fofonoff and R. C. Millard, Jr., Unesco Tech. Papers in Mar. Sci. No. 44 (1983)], and on calculations from temperature and salinity profiles. The pressure to depth conversion is presented first. The equations can be used in those cases where the desired accuracy is reduced to ±0.8 m. The equations to convert depth to pressure provide an overall accuracy between ±8000 Pa and ±1000 Pa. This leads to errors in sound speed consistently smaller than ±0.02 m/s. The discussion, and comparisons with results and other formulas, suggest that the new equations are a substantial improvement on the previous simplified ones, which should now be abandoned.
    Type: Article , PeerReviewed
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  • 6
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    Seismic attributes and their classification (1996)
    American Institute of Physics
    In:  The Leading Edge, 15 (10). p. 1090.
    Details
    Publication Date: 2016-08-30
    Description: Attributes have proliferated recently with different selections available on different workstations. What do they all mean? When do we use one and when another? The answers to these questions are not easy but the first step is to understand what our options are, and herein lies the purpose of this article.
    Type: Article , PeerReviewed
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  • 7
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    Optimum frequencies for noise‐limited active sonar detection (1981)
    American Institute of Physics
    In:  The Journal of the Acoustical Society of America, 70 (5). pp. 1336-1338.
    Details
    Publication Date: 2020-05-11
    Description: The curves of optimum frequencies versus maximum range for active sonar detection under specific sets of assumptions are presented for the more recent expressions for attenuation given by Lovett [J. Acoust. Soc. Am. 58, 620–625 (1975)] for the eastern North Pacific and Thorp [J. Acoust. Soc. Am. 42, 270 (1967)] for the western North Atlantic as corrected at low frequencies by Kibblewhite et al. [J. Acoust. Soc. Am. 60, 1040–1047 (1976)].
    Type: Article , PeerReviewed
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