Fully nonlinear numerical wave tank (NWT) simulations and wave run-up prediction around 3-D structures     

J. -C. Park  M. -H. Kim  H. Miyata  H. -H. Chun 《Ocean Engineering》2003,30(15):1969-1996

A finite-difference scheme and a modified marker-and-cell (MAC) algorithm have been developed to investigate the interactions of fully nonlinear waves with two- or three-dimensional structures of arbitrary shape. The Navier–Stokes (NS) and continuity equations are solved in the computational domain and the boundary values are updated at each time step by the finite-difference time-marching scheme in the framework of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique developed for two fluid layers.To demonstrate the capability and accuracy of the present method, the numerical simulation of backstep flows with free-surface, and the numerical tests of the MDF technique with limit functions are conducted. The 3D program was then applied to nonlinear wave interactions with conical gravity platforms of circular and octagonal cross-sections. The numerical prediction of maximum wave run-up on arctic structures is compared with the prediction of the Shore Protection Manual (SPM) method and those of linear and second-order diffraction analyses based on potential theory and boundary element method (BEM). Through this comparison, the effects of non-linearity and viscosity on wave loading and run-up are discussed.  相似文献   

Seasonality and selectivity in the feeding ecology and reproductive biology of deep-sea bathyal holothurians     

Ian R. Hudson  Benjamin D. Wigham  David S. M. Billett  Paul A. Tyler 《Progress in Oceanography》2003,59(4):381-407

Chlorophyll and carotenoid pigments were determined from the gut sediments of five species of bathyal holothurian in the NE Atlantic, sampled shortly after the spring/summer phytoplankton bloom in 2001 and prior to the spring bloom in 2002. Three species, Laetmogone violacea, Paroriza pallens and Bathyplotes natans, sampled within a similar depth range (900–1100 m) in the summer of 2001 showed significant differences in their chlorophyll and carotenoid pigment concentrations. This suggests they may select for slightly different components from the available food resource. Four species sampled in early spring 2002, Laetmogone violacea, Paroriza pallens, Benthogone rosea and Benthothuria funebris, also had significant differences in their pigment concentrations. These species were sampled over a wider depth range (1000–3100 m) showing a bathymetric trend in pigment concentrations. There was a distinct seasonal change in the composition and concentration of the pigments, linked to a reduction in the availability of fresh organic material during autumn and winter periods.Ovarian tissue was also examined. The carotenoid pigments found in the ovary also occurred in the OM ingested by the holothurians. The dominant gonadal carotenoid pigments were β-carotene, echinenone and zeaxanthin. The potential for using these carotenoids to gain a competitive advantage through selectivity of chlorophyll and carotenoid pigment biomarkers are discussed in relation to competition for food resources by deposit-feeders. The results were also compared with selectivity in abyssal species.  相似文献   

Dynamics and control of a towed underwater vehicle system, part I: model development     

B. Buckham  M. Nahon  M. Seto  X. Zhao  C. Lambert 《Ocean Engineering》2003,30(4):82-470

Autonomous vehicles are being developed to replace the conventional, manned surface vehicles that tow mine hunting towed platforms. While a wide body of work exists that describes numerical models of towed systems, they usually include relatively simple models of the towed bodies and neglect the dynamics of the towing vehicle. For systems in which the mass of the towing vehicle is comparable to that of the towed vehicle, it becomes important to consider the dynamics of both vehicles. In this work, we describe the development of a numerical model that accurately captures the dynamics of these new mine hunting systems. We use a lumped mass approximation for the towcable and couple this model to non-linear numerical models of an autonomous surface vehicle and an actively controlled towfish. Within the dynamics models of the two vehicles, we include non-linear controllers to allow accurate maneuvering of the towed system.  相似文献   

Research challenges at the land–sea interface     

Drew M. Talley  Elizabeth W. North  Andrew R. Juhl  David A. Timothy  Daniel Conde  Jody F. C. deBrouwer  Cheryl A. Brown  Linda M. Campbell  Tobias Garstecki  Catherine J. Hall  Filip J. R. Meysman  David M. Nemerson  Pedro W. Souza Filho  Robert J. Wood 《Estuarine, Coastal and Shelf Science》2003,58(4):699

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Characterization of Estuarine Marine Clays for Coastal Reclamation in Pusan, Korea     

S. G. Chung  P. H. Giao  T. S. Nagaraj  J. M. Kwag 《Marine Georesources & Geotechnology》2002,20(4):237-254

Large scale reclamation works in coastal areas of the Nakdong River plain are at various stages of progress, since early 1990's on in-situ soft marine clay deposits. These deposits are of the order of 30 to 40 m thick. A realistic rapid characterization of soft ground would ensure success of any reclamation work in this area. In order to cope with the work carried out with different agencies, it is desirable to evolve a systematic methodology. In this study, engineering properties of clays at three coastal areas, Gadukdo, Noksan and Shinho, have been generated. The analysis of data has been done within the framework of classical developments in soil mechanics. Analysis has also been made by making use of the recent developments in dealing with soft clays. The dominant factors, namely, stress, time, and environment influencing the response of clay to loading are identified.  相似文献   

Physical and biological conditions and processes in the northeast Pacific Ocean     

Harold P. Batchelder  Thomas M. Powell 《Progress in Oceanography》2002,53(2-4)

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Atmospheric forcing of the southeast Bering Sea Shelf during 1995–99 in the context of a 40-year historical record     

N. A. Bond  J. M. Adams   《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26):5869-5887

The atmospheric forcing of the Bering Sea over its eastern shelf is estimated using the 40-year record of daily data from the NCEP/NCAR Reanalysis. This data set includes estimates of the processes responsible for the atmospheric forcing, namely the surface fluxes of momentum, sensible and latent heat, and longwave and shortwave radiation, and therefore permits quantifying effects that previously could be inferred only from the large-scale nature of the flow. The forcing in 1995–1999 is described in detail using daily time series; historical context for these results is provided with seasonal averages for the years 1959–1999.The analysis for winter concentrates on aspects related to the formation and advection of sea ice. Results indicate that the presence of sea ice is strongly related to the net surface-heat fluxes as well as the cross-shelf component of the wind. The 40-year record lacks any discernible long-term trend in the winter forcing and response. There was a notably cold period in the early to middle 1970s, and a warm period from the late 1970s into the early 1980s, but conditions during the 1990s are similar to those in the late 1950s and 1960s.The analysis for the warm season focuses on the mechanisms responsible for the variability in SST warming. Much of the intraseasonal and interannual variability in this warming can be attributed to variations in the downward shortwave radiation (solar heating). The 40-year record does indicate a long-term trend toward increased solar heating, and reduced surface latent-heat fluxes (evaporative cooling). These changes have led to August SSTs in the 1990s that are roughly 1°C warmer than in the 1960s.  相似文献   

Modern sediment supply to the lower delta plain of the Ganges-Brahmaputra River in Bangladesh     

M. Allison  E. Kepple 《Geo-Marine Letters》2001,21(2):66-74

Vibracores and auger samples collected from the lower (tidal) delta plain of the Ganges-Brahmaputra River in Bangladesh were examined to determine whether the area is a significant sink for riverine sediments. Measurements of ¹³⁷Cs activity and radiocarbon in the sediments indicate sediment accumulation is taking place on decadal and millennial time scales at rates reaching 1.1 cm/year. The sediment of the lower delta plain is primarily derived from an offshore source after having originally been supplied by the Ganges-Brahmaputra river system, carried westward by prevailing currents and advected inland by monsoonal coastal setup and cyclonic events.  相似文献   

Effects of crustacean traps on benthic fauna     

Eno  N. Clare; MacDonald  David S.; Kinnear  Jim A. M.; Amos  S. Chris; Chapman  Colin J.; Clark  Robin A.; Bunker  Francis St P.D.; Munro  Colin 《ICES Journal of Marine Science》2001,58(1):11-20

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Erratum     

Marteinsdottir  Gudrun; Gunnarsson  Bjorn; Suthers  Iain M. 《ICES Journal of Marine Science》2001,58(1):361

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