Little William S.

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Little
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William S.
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  • Working Paper
    LFASE data processing system overview
    (Woods Hole Oceanographic Institution, 1990-06) Little, William S. ; Bolmer, S. Thompson ; Stephen, Ralph A.
    This technical report provides an overview of the LFASE data processing system. This software system is made up of over twenty-five programs which are used to acquire, reduce, and analyze acoustic seismic data collected during the Low Frequency Acoustic Seismic Experiment (LFASE) (Stephen et al, 1989; Koelsch et al, 1990). This report is directed at scientific and engineering personnel who wish to understand the overall LFASE data processing system as well as the individual processing procedures which are utilized during each stage of data reduction and interpretation. The report is also directed at programmers, data processors, technicians, and other individuals who plan to work with LFASE programs and data.
  • Working Paper
    LFASE data transcription software CGG2ROSE2 version 1.1 : program report
    (Woods Hole Oceanographic Institution, 1990-05) Little, William S. ; Galbraith, Nancy R. ; Bolmer, S. Thompson
    Seismic data obtained using borehole seismometers during the LFASE experiment (Stephen et al, 1989; Koelsch et al, 1990) are retrieved from the seafloor instrument package and converted to a data format more suitable for analysis with existing computer systems. This report describes the computer program CGG2ROSE2 for converting LFASE optical disk files recorded in CGG format by the data acquisition computer into standard ROSE format data files on a VAX/VMS computer. CGG2ROSE2 provides features for rearranging LFASE data into smaller segments, making corrections to timing information, and replacing file header information.
  • Technical Report
    WHOI silhouette DIGITIZER version 1.0 user’s guide
    (Woods Hole Oceanographic Institution, 2003-07) Little, William S. ; Copley, Nancy J.
    WHOI Silhouette DIGITIZER is a MATLAB-based computer program for measuring the lengths of marine organisms in the macrozooplankton size range. DIGITIZER displays a scanned photographic image of a seawater slurry containing large numbers of marine organisms, upon which is superimposed a reference grid. DIGITIZER then allows you to measure the organisms' lengths using the cursor on the computer screen. DIGITIZER automatically calculates each organism’s biomass and generates spreadsheet compatible output listings of basic statistics derived from the data. DIGITIZER also produces text files of lengths, weights, and size-frequency histograms.
  • Working Paper
    AFRAME : a video animation capability for displaying FINDIF numerical model output
    (Woods Hole Oceanographic Institution, 1995-07) Little, William S. ; Stephen, Ralph A.
    This report describes the development of a facility for recording time-varying computer graphics on video tape. The primary purpose of the facility is to produce animation sequences of ocean and seafloor acoustic wave fields from output of the synthetic seismogram numerical model FINDIF, and to record them on convenient portable VHS video tapes. The facility utilizes a suite of computer programs called AFRAME, and an Abekas model A60 digital video disk which is connected to the modeling computer and to broadcast quality video recording equipment.
  • Working Paper
    Signal and noise levels in numerical scattering chamber snapshots
    (Woods Hole Oceanographic Institution, 1995-05) Swift, Stephen A. ; Little, William S. ; Stephen, Ralph A.
    A study was carried out to quantify the level of numerical noise in numerical scattering chamber (NSC) calculations and to compare these noise levels with signal levels of body waves, interface waves and ambient noise. The amplitudes of signal and noise in snapshots from the numerical scattering chamber were quantified at 50 and 65 periods for a few reference models. Models with homogeneous subseafloor structure were studied to determine the level of numerical noise; models with a wavenumber-correlation length product of one were examined to determine signal levels. Models were run with both Higdon and telegraph equation absorbing boundaries since the numerical noise within the grid depends on the boundary formulation. Amplitudes were measured along data traces obtained at a grid depth of 3.33 λw and at the seafloor. Forward traveling head waves had typical amplitudes of ±125 but may reached ±250 near the direct wave. Diffraction amplitudes were observed up to ±300. Stoneley wave amplitudes ranged from ±800 up to ±20,000. Numerical noise levels were less than ±25 in most areas of the water and less than ±350 along most of the seafloor. Regardless of the absorbing boundary type, however, there was a region of noise extending up to 15 λw behind the first seafloor reflection at 3.33 λw in which noise levels range from ±100 up to ±600. In this region it is difficult to resolve signal from systematic numerical noise.