Now showing items 420-439 of 843

  • K-distribution fading models for Bayesian estimation of an underwater acoustic channel 

    Laferriere, Alison Beth (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2011-02)
    Current underwater acoustic channel estimation techniques generally apply linear MMSE estimation. This approach is optimal in a mean square error sense under the assumption that the impulse response fluctuations are well ...
  • The Kallisti Limnes, carbon dioxide-accumulating subsea pools 

    Camilli, Richard; Nomikou, Paraskevi; Escartin, Javier; Ridao, Pere; Mallios, Angelos; Kilias, Stephanos P.; Argyraki, Ariadne; Andreani, Muriel; Ballu, Valerie; Campos, Ricard; Deplus, Christine; Gabsi, Taoufic; Garcia, Rafael; Gracias, Nuno; Hurtos, Natalia; Magi, Lluis; Mevel, Catherine; Moreira, Manuel; Palomeras, Narcis; Pot, Olivier; Ribas, David; Ruzie, Lorraine; Sakellariou, Dimitris (Nature Publishing Group, 2015-07-16)
    Natural CO2 releases from shallow marine hydrothermal vents are assumed to mix into the water column, and not accumulate into stratified seafloor pools. We present newly discovered shallow subsea pools located within the ...
  • Kalman filter estimation of underwater vehicle position and attitude using Doppler velocity aided inertial motion unit 

    Leader, Daniel Eugene (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1994-09)
    This Paper explores the use of an extended Kalman filter to provide real-time estimates of underwater vehicle position and attitude. The types of previously available sensors are detailed including strapdown accelerometers, ...
  • Kinematic evaluation of end effector design 

    Edwards, Gary W. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1992-09)
    The complex, many degree-of-freedom end effectors at the leading edge of technology would be unusable in the sea bottom research environment. Simpler designs are required to provide adequate reliability for subsea ...
  • Laboratory evaluation of laser-induced breakdown spectroscopy (LIBS) as a new in situ chemical sensing technique for the deep ocean 

    Michel, Anna Pauline Miranda (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-09)
    Present-day expeditionary oceanography is beginning to shift from a focus on short- term ship and submersible deployments to an ocean observatory mode where long- term temporally-focused studies are feasible. As a result, ...
  • Laboratory measurements of high-frequency, acoustic broadband backscattering from sea ice and crude oil 

    Bassett, Christopher; Lavery, Andone C.; Maksym, Ted; Wilkinson, Jeremy P. (Acoustical Society of America, 2014-12-18)
    Recent decreases in summer sea ice cover are spurring interest in hydrocarbon extraction and shipping in Arctic waters, increasing the risk of an oil spill in ice covered waters. With advances in unmanned vehicle operation, ...
  • Laboratory measurements of the sound generated by breaking waves 

    Loewen, Mark Richard (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1991-12)
    Breaking waves dissipate energy, transfer momentum from the wind to surface currents and breaking enhances the transfer of gas and mass across the air-sea interface. Breaking waves are believed to be the dominant source ...
  • Laboratory observations of double-diffusive convection using high-frequency broadband acoustics 

    Ross, Tetjana; Lavery, Andone C. (2008-09)
    High-frequency broadband (200-300 kHz) acoustic scattering techniques have been used to observe the diffusive regime of double-diffusive convection in the laboratory. Pulse compression signal processing techniques allow ...
  • The landward and seaward mechanisms of fine-sediment transport across intertidal flats in the shallow-water region—A numerical investigation 

    Hsu, Tian-Jian; Chen, Shih-Nan; Ogston, Andrea S. (2011-03-15)
    This study investigates transport of fine sediment across idealized intertidal flats with emphasis on resolving processes at the tidal edge, which is defined as the very shallow region of the land-water interface. We first ...
  • Large-area visually augmented navigation for autonomous underwater vehicles 

    Eustice, Ryan M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2005-06)
    This thesis describes a vision-based, large-area, simultaneous localization and mapping (SLAM) algorithm that respects the low-overlap imagery constraints typical of autonomous underwater vehicles (AUVs) while exploiting ...
  • Large-eddy simulation of the tidal-cycle variations of an estuarine boundary layer 

    Li, Ming; Radhakrishnan, Senthilkumaran; Piomelli, Ugo; Geyer, W. Rockwell (American Geophysical Union, 2010-08-03)
    The estuarine boundary layer affected by a horizontal density gradient exhibits temporal evolution over a tidal cycle, in a manner similar to the diurnal cycle of the ocean surface mixed layer. A large eddy simulation (LES) ...
  • Larval dispersion along an axially symmetric mid-ocean ridge 

    McGillicuddy, Dennis J.; Lavelle, J. William; Thurnherr, Andreas M.; Kosnyrev, V. K.; Mullineaux, Lauren S. (2009-12-22)
    We investigated planktonic larval transport processes along an axially symmetric mid-ocean ridge with characteristics similar to that of the East Pacific Rise (EPR) segment at 9-10°N. The hydrodynamic basis for this study ...
  • Laser diffraction particle sizing : sampling and inversion 

    Riley, James B. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1987-08-13)
    The inverse problem of obtaining particle size distributions from observations of the angular distribution of near forward scattered light is reexamined. Asymptotic analysis of the forward problem reveals the ...
  • Laser Raman spectroscopy as a technique for identification of seafloor hydrothermal and cold seep minerals 

    White, Sheri N. (2008-11)
    In situ sensors capable of real-time measurements and analyses in the deep ocean are necessary to fulfill the potential created by the development of autonomous, deep-sea platforms such as autonomous and remotely operated ...
  • Lateral circulation and sediment transport driven by axial winds in an idealized, partially mixed estuary 

    Chen, Shih-Nan; Sanford, Lawrence P.; Ralston, David K. (American Geophysical Union, 2009-12-03)
    A 3D hydrodynamic model (ROMS) is used to investigate lateral circulation in a partially mixed estuary driven by axial wind events and to explore the associated transport of sediments. The channel is straight with a ...
  • Linearity of fisheries acoustics, with addition theorems 

    Foote, Kenneth G. (Acoustical Society of America, 1983-06)
    An experiment to verify the basic linearity of fisheries acoustics is described. Herring (Clupea harengus L.) was the subject fish. Acoustic measurements consisted of the echo energy from aggregations of encaged but otherwise ...
  • The load/deflection behavior of pretensioned cable/pulley transmission mechanisms 

    Snow, Edward R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-12)
    Mechanical transmission mechanisms enable a designer to match the abilities (e .g. velocity, torque capacity) of an actuator to the needs of an application. Unfortunately the mechanical limitations of the transmission ...
  • LOCOMOOR : a LOw-COst MOORing for the measurement of internal solitary waves 

    Lord, Jeffrey; Irish, James D.; Duda, Timothy F.; Kemp, John N. (2000-05-09)
    In order to supplement the ASIAEX field effort to measure the temporal and spatial structure of the internal solitary wave field in relationship to acoustic propagation and scattering studies, an array of low-cost ...
  • Long distance passive localization of vocalizing sei whales using an acoustic normal mode approach 

    Newhall, Arthur E.; Lin, Ying-Tsong; Lynch, James F.; Baumgartner, Mark F.; Gawarkiewicz, Glen G. (Acoustical Society of America, 2012-02)
    During a 2 day period in mid-September 2006, more than 200, unconfirmed but identifiable, sei whale (Balaenoptera borealis) calls were collected as incidental data during a multidisciplinary oceanography and acoustics ...
  • Long-baseline acoustic navigation for under-ice autonomous underwater vehicle operations 

    Jakuba, Michael V.; Roman, Christopher N.; Singh, Hanumant; Murphy, Christopher A.; Kunz, Clayton G.; Willis, Claire; Sato, Taichi; Sohn, Robert A. (2008-05-19)
    The recent Arctic GAkkel Vents Expedition (AGAVE) to the Arctic Ocean’s Gakkel Ridge (July/August 2007) aboard the Swedish ice-breaker I/B Oden employed autonomous underwater vehicles (AUVs) for water-column and ocean ...