Now showing items 560-579 of 854

  • On the echo interference in sound backscattering by densely aggregated targets 

    Gorska, Natalia; Chu, Dezhang (2004-12-01)
    It is important to understand the volume backscattering by dense aggregations of a variety of scattering objects such as bubbles or biological targets. This paper addresses the interference of the echoes from randomly ...
  • On the electromagnetic fields produced by marine frequency domain controlled sources 

    Chave, Alan D. (John Wiley & Sons, 2009-10-14)
    In recent years, marine controlled source electromagnetics (CSEM) has found increasing use in hydrocarbon exploration due to its ability to detect thin resistive zones beneath the seafloor. Although it must be recognized ...
  • On the statistics of magnetotelluric rotational invariants 

    Chave, Alan D. (Oxford University Press on behalf of The Royal Astronomical Society, 2013-10-25)
    The statistical properties of the Swift skew, the phase-sensitive skew and the WAL invariants I1−I7 and Q are examined through analytic derivation of their probability density functions and/or simulation based on a Gaussian ...
  • On the turbulent co-spectrum of two scalars and its effect on acoustic scattering from oceanic turbulence 

    Ross, Tetjana; Garrett, Christopher; Lueck, Rolf (Cambridge University Press, 2004-08-24)
    While acoustic scatter from oceanic turbulence is sensitive to temperature–salinity covariations, there are unfortunately no published measurements of the turbulent temperature–salinity co-spectrum. Several models have ...
  • On whether azimuthal isotropy and alongshelf translational invariance are present in low-frequency acoustic propagation along the New Jersey shelfbreak 

    Lynch, James F.; Emerson, Chris; Abbot, Philip A.; Gawarkiewicz, Glen G.; Newhall, Arthur E.; Lin, Ying-Tsong; Duda, Timothy F. (Acoustical Society of America, 2012-02)
    To understand the issues associated with the presence (or lack) of azimuthal isotropy and horizontal (along isobath) invariance of low-frequency (center frequencies of 600 Hz and 900 Hz) acoustic propagation in a shelfbreak ...
  • Optical tools for ocean monitoring and research 

    Moore, C.; Barnard, A.; Fietzek, P.; Lewis, Marlon R.; Sosik, Heidi M.; White, Sheri N.; Zielinski, O. (Copernicus Publications on behalf of the European Geosciences Union, 2009-12-10)
    Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based ...
  • Optimal mode localization in disordered, periodic structures 

    Rajagopal, Gopalkrishna (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-02)
    Periodic structures which are slightly disordered undergo dramatic changes in mode shapes such that the responses go from being spatially extended to spatially localized. This phenomenon called mode localization, offers ...
  • Optimal source localization and tracking using arrays with uncertainties in sensor locations 

    Segal, Mordechai; Weinstein, Ehud (Woods Hole Oceanographic Institution, 1989-08)
    We develop a computationally efficient iterative algorithm for source localization and tracking using active/passive arrays with uncertainties in sensor locations. We suppose that the available data consist of time delay, ...
  • Optimizing copper spheres for precision calibration of hydroacoustic equipment 

    Foote, Kenneth G. (Acoustical Society of America, 1982-03)
    An operational definition of backscattering cross section is developed for the wideband reception of finite echoes. This is supported by relative measurements on a set of copper spheres by each of four echo sounders operating ...
  • Orientation dependence of broadband acoustic backscattering from live squid 

    Lee, Wu-Jung; Lavery, Andone C.; Stanton, Timothy K. (Acoustical Society of America, 2012-06)
    A controlled laboratory experiment of broadband acoustic backscattering from live squid (Loligo pealeii) was conducted using linear chirp signals (60–103 kHz) with data collected over the full 360° of orientation in the ...
  • Orientation dependence of the acoustic backscatter for elongated zooplankton 

    Johnson, Matthew L. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-09)
    The width of the main lobe of the acoustic backscatter directivity pattern of decapod shrimp (Palaemonetes vulgaris) is examined versus acoustic frequency. Using the distorted wave Born approximation (DWBA) and the ...
  • Overview of results from the Asian Seas International Acoustics Experiment in the East China Sea 

    Dahl, Peter H.; Zhang, Renhe; Miller, James H.; Bartek, Louis R.; Peng, Zhauhui; Ramp, Steven R.; Zhou, Ji-Xun; Chiu, Ching-Sang; Lynch, James F.; Simmen, Jeffrey A.; Spindel, Robert C. (IEEE, 2004-10)
    The Asian Seas International Acoustics Experiment (ASIAEX) included two major field programs, one in the South China Sea and the other in the East China Sea (ECS). This paper presents an overview of research results from ...
  • A parallel hypothesis method of autonomous underwater vehicle navigation 

    LaPointe, Cara Elizabeth Grupe (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2009-06)
    This research presents a parallel hypothesis method for autonomous underwater vehicle navigation that enables a vehicle to expand the operating envelope of existing long baseline acoustic navigation systems by incorporating ...
  • Particle fluxes associated with mesoscale eddies in the Sargasso Sea 

    Buesseler, Ken O.; Lamborg, Carl H.; Cai, Pinghe; Escoube, Raphaelle; Johnson, Rodney J.; Pike, Steven M.; Masque, Pere; McGillicuddy, Dennis J.; Verdeny, E. (2007-09-25)
    We examined the impact of a cyclonic eddy and mode-water eddy on particle flux in the Sargasso Sea. The primary method used to quantify flux was based upon measurements of the natural radionuclide, 234Th, and these flux ...
  • Passive acoustic detection of deep-diving beaked whales 

    Zimmer, Walter M. X.; Harwood, John; Tyack, Peter L.; Johnson, Mark P.; Madsen, Peter T. (Acoustical Society of America, 2008-11)
    Beaked whales can remain submerged for an hour or more and are difficult to sight when they come to the surface to breathe. Passive acoustic detection (PAD) not only complements traditional visual-based methods for detecting ...
  • A passive capture latch for ODYSSEY-class AUVs 

    Bowen, Martin F. (Woods Hole Oceanographic Institution, 1998-06-12)
    Under subcontract to the Massachusetts Institute of Techology's (MIT) Sea Grant Autonomous Ocean Sampling Network (AOSN) program, the Woods Hole Oceanographic Institution's Deep Submergence Laboratory (WHOI-DSL) produced ...
  • Passive localization of underwater acoustic beacons 

    Wojcik, Dennis M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-09)
    This thesis examines the use of a single, omnidirectional hydrophone as a receiving sensor to passively localize an acoustic beacon. The localization problem is presented as a constrained, nonlinear parameter estimation ...
  • Passive time reversal acoustic communications through shallow-water internal waves 

    Song, Aijun; Badiey, Mohsen; Newhall, Arthur E.; Lynch, James F.; DeFerrari, Harry A.; Katsnelson, Boris G. (IEEE, 2010-11-30)
    During a 12-h period in the 2006 Shallow Water Experiment (SW06), binary phase shift keying (BPSK) signals at the carrier frequencies of 813 and 1627 Hz were propagated over a 19.8-km source–receiver range when a packet ...
  • Passive wake detection using seal whisker-inspired sensing 

    Beem, Heather R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02)
    This thesis is motivated by biological experiments, which display the harbor seal's ability to track the wake of an object several seconds after it swam by. In this work, I elucidate the basic fluid mechanisms that seals ...
  • A pendulum inclinometer for use with small deep-submersibles 

    Sharp, Arnold G.; Sullivan, James R. (Woods Hole Oceanographic Institution, 1976-09)
    The authors developed a pendulum inclinometer suitable for use with small deepsubmersibles or surface craft. The instrument uses a relatively short heavy pendulum and a viscous damping system for minimizing the effects ...