A bucket wheel dredge system for offshore tin mining beyond the 50 m water depth     

A. Albar  R. E. Randall  B. Dwibarto  B. L. Edge 《Ocean Engineering》2002,29(14):1751-1767

A bucket wheel dredge (BWD) for offshore tin mining is part of the long term plan of PT Timah Tbk to identify new dredging technologies for mining in greater than 50 m water depths. Measured tin-ore physical properties are used in a new BWD computer model to investigate deep water tin mining. The model simulates the cutting and hydraulic transport of submerged tin-ore. The results show that hydraulic tin mining beyond water depths of 50 m is feasible. It is best to employ hydraulic transport for lifting the tin-ore from the ocean floor to the surface and to use barges to transport the tin-ore to land processing plants.  相似文献   

Cohesive sediment transport in the 3D-hydrodynamic-baroclinic circulation model,: study case for idealized tidal inlet     

Wahyu W. Pandoe  Billy L. Edge 《Ocean Engineering》2004,31(17-18):2227-2252

This work provides a general hydrodynamic circulation model that can be used to understand density driven flows, which may arise in the case of suspension of fine-grained materials. The research is expected to provide a better understanding of the characteristics of spatial and temporal variability of current, which is associated with the period of ebb and flood tidal cycles.The model development includes extending the existing three-dimensional (3D) ADCIRC model with (1) baroclinic forcing term and (2) transport module of suspended and soluble materials. The transport module covers the erosion, material suspension and deposition processes for cohesive type sediment. In the case of an idealized tidal inlet in stratified water, the inclusion of baroclinic term can demonstrate the prevailing longshore sediment transport. It is shown that the model has application to the transport of the cohesive sediments from the mouth of the Mississippi River along the north shore of the Gulf of Mexico towards and along the Texas coast.  相似文献   

Three-dimensional hydrodynamic model, study cases for quarter annular and idealized ship channel problems     

W. W. Pandoe  B. L. Edge 《Ocean Engineering》2003,30(9):1117-1135

An extended version of the three-dimensional hydrodynamic model, ADCIRC 3D-DSS, was utilized to simulate both horizontal and vertical flows in a (quarter) annular harbor (QATP and ATP) and rectangular basin with an idealized ship channel (RBSC). Comparison of horizontal and vertical solutions to the analytical solution and results of other researchers are in good agreement. The vertical velocity solution is highly sensitive to the horizontal velocity solutions. The presence of the sidewall boundary may also affect the vertical solutions. Around the sloping bank of RBSC channel with one-third gradient, the vertical velocity becomes important. The maximum vertical velocity approaches ±50% of the sediment fall velocity of fine sand.  相似文献   

Dark times for dageraad Chrysoblephus cristiceps: evidence for stock collapse     

D Parker  H Winker  CG Attwood  SE Kerwath 《African Journal of Marine Science》2016,38(3):341-349

The declaration of a state of emergency in the South African linefishery in 2000 has had a positive impact on a few overexploited endemic seabreams (Family Sparidae). However, the population of the reef-dwelling dageraad Chrysoblephus cristiceps has been unresponsive to progressively stricter management regulations. After decades of unsustainable fishing mortality the species is in a critical state. In this paper, a method based on standardised probability of capture is used to develop an index of relative abundance for rare species, such as dageraad, which is more robust to changes in output control regulations than conventional methods. The results show a severe decline in dageraad capture probability in the south-west region of South Africa, from 8% in 1985 to <0.1% in 2011. The east region experienced a more rapid decline, from 24% in 1999 to <0.1% in 2011. A spatial comparison of the distribution of historical and recent dageraad probability of capture along the South African coastline indicates a range contraction commonly associated with the collapse of a population. The once-widespread species is now largely limited to a few locations in the Eastern Cape province and dageraad is mostly absent across its former western distribution. Although the historical decline has commonly been attributed to commercial overexploitation, the recreational sector had an estimated 3–5 times greater impact on the dageraad population than the commercial sector in recent years. Given that previous management regulations have been unsuccessful in arresting the decline of dageraad populations, assertive management is necessary to ensure the species’ sustainability. Rehabilitation of dageraad stocks will require a further decrease in fishing mortality, in conjunction with maintaining an appropriate marine protected area (MPA) network.  相似文献   

A necessary voice: Climate change and lived experiences of youth in Rigolet,Nunatsiavut, Canada     

Joanna Petrasek MacDonald  Sherilee L. Harper  Ashlee Cunsolo Willox  Victoria L. Edge 《Global Environmental Change》2013,23(1):360-371

Globally, youth voices and their experiences, observations, and perceptions about climatic and environmental change and variability are relatively absent in the published literature to date. To address this gap, the goal of this research was to explore the observations and perceptions of climate change held by youth (12–25 years old) in the Inuit community of Rigolet, Nunatsiavut, Canada. Twenty in-depth interviews were conducted with youth in Rigolet to gather data about climatic and environmental changes young people have observed, and the subsequent impacts of these changes on their lives, culture, and community. Youth reported observing and experiencing climatic and environmental changes throughout their lives, with reported impacts falling within five main themes: changing travel conditions and access to hunting; challenges to Inuit culture; a concern for Elder and senior well-being; strong climate-related emotional responses; and youth-identified potential adaptation strategies. More broadly, this research demonstrated that young people have valuable knowledge and perspectives to offer. In particular, researchers, community leaders, and policy makers are encouraged to meaningfully engage youth as crucial stakeholders in future climate change work, research, dialogue, and policy.  相似文献   

Optical properties of Small Magellanic Cloud X-ray binaries     

M. J. Coe  W. R. T. Edge  J. L. Galache  V. A. McBride 《Monthly notices of the Royal Astronomical Society》2005,356(2):502-514

This work represent the first major study of the optical and infrared characteristics of the mass donor companions to the X-ray pulsars in the Small Magellanic Cloud (SMC). In this work several new counterparts have been identified, and possible ones confirmed, as companions to X-ray pulsars in the SMC giving a total of 34 such objects now identified. In addition this work presents three new binary periods and confirms two X-ray periods using optical data for objects in this group. This homogeneous sample has been studied as a group to determine important general characteristics that may offer an insight into the evolution of such systems. In particular, the spectral class distribution shows a much greater agreement with those of isolated Be stars, and appears to be in some disagreement with the galactic population of Be stars in Be/X-ray binaries. Studies of the long-term optical modulation of the Be star companions reveal an extremely variable group of objects, a fact which will almost certainly make a major contribution to the pronounced X-ray variability. The spatial distribution of these systems within the SMC is investigated and strongly suggests a link between massive star formation and the H  i density distribution. Finally, studies of the circumstellar disc characteristics reveal a strong link with optical variability offering important clues into the long-term stability of such discs.  相似文献   

The Las Campanas/Anglo–Australian Telescope Rich Cluster Survey – III. Spectroscopic studies of X-ray bright galaxy clusters at z∼ 0.1     

Kevin A. Pimbblet  Ian Smail  Alastair C. Edge  Eileen O'Hely  Warrick J. Couch  Ann I. Zabludoff 《Monthly notices of the Royal Astronomical Society》2006,366(2):645-666

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Three new X-ray pulsars detected in the Small Magellanic Cloud and the positions of two other known pulsars determined     

W. R. T. Edge  M. J. Coe  J. L. Galache  V. A. McBride  R. H. D. Corbet  C. B. Markwardt  S. Laycock 《Monthly notices of the Royal Astronomical Society》2004,353(4):1286-1292

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A measurement of H₀ from Ryle Telescope, ASCA and ROSAT observations of Abell 773     

Richard Saunders  Rüdiger Kneissl  Keith Grainge  William F. Grainger  Michael E. Jones  Alessia Maggi  Rhiju Das  †  Alastair C. Edge  Anthony N. Lasenby  G. G. Pooley  Shigeru J. Miyoshi  Taisuke Tsuruta  Koujun Yamashita  Yuzuru Tawara  Akihiro Furuzawa  Akihiro Harada  Izamu Hatsukade 《Monthly notices of the Royal Astronomical Society》2003,341(3):937-940

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The Las Campanas/AAT Rich Cluster Survey – II. The environmental dependence of galaxy colours in clusters at z∼0.1     

Kevin A.Pimbblet  IanSmail  TadayukiKodama  Warrick J.Couch  Alastair C.Edge  Ann I.Zabludoff  EileenO'Hely 《Monthly notices of the Royal Astronomical Society》2002,331(2):333-350

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