Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Current speed"”.
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Characterizing and comparing the spawning habitats of anchovy (Engraulis capensis) and sardine (Sardinops sagax) in the Southern Benguela upwelling ecosystem
… physical and biological data were collected concurrently with egg samples. Physical variables measured included sea surface temperature, nitrate concentration, water depth, salinity, current speed, wind speed and mixed layer depth, whereas biological variables included phytoplankton biomass (as …
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Environmental drivers of variation in shellfish landings in Shetland creel fisheries
… <i>a</i> concentrations (Chl <i>a</i>), wind speed and direction and tidal current speed. Exploratory time series analyses in four areas using generalised additive mixed models (GAMMs) revealed that differenced SST and Chl <i>a</i> (with seasonal trends removed) had very little effect on LPUE …
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Investigating sediment size distributions and size-specific Sm-Nd isotopes as paleoceanographic proxy in the North Atlantic Ocean: reconstructing past deep-sea current speeds since Last Glacial Maximum
… Meridional Overturning Circulation (AMOC) flow speed, particle size distributions (weight%, Sortable Silt mean grain size) and grain-size separated (0–4, 4–10, 10–20, 20–30, 30–40 and 40–63 µm) Sm-Nd isotopes and trace element concentrations are measured on 12 cores along the flow-path of …
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Dispersion of material by wind and tide in shallow seas
… action of Langmuir circulation and a mean current. The numerical simulations show the general patterns the plume will form, with initial meanders leading to the formation of distinct windrows. The analytical model shows that the lateral diffusivity, the rate of across-current dispersion of …
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Population Status of Beaver on the Free-running Missouri River in Southeastern South Dakota
… river showed a significantly higher (P < 0. 01) current speed 2 m from the shoreline in the stabilized subsection and no significant difference (P > 0. 05) in river depth at 2 m from the shoreline. Distance from beaver dens to standing willows (Salix spp.) and cottonwoods (Populus deltoides) was …
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Behavioral ecology of coral reef fishes at spawning aggregation sites
… variables measured included time of day, tides, current velocity, current speed and abundance of piscivorous predators, and were correlated with observed spawning outputs through multifactorial analyses. High interspecific variability in spawning patterns was found among the eleven monitored …
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A numerical investigation of tidal current circulation in the Gulf of Maine
… is used to computer tidal heights and tidal currents in the Gulf of Maine. The model uses two adjacent open boundaries at which the tides are prescribed at each time step, using four tidal constituents. The grid size is six nautical miles and the time step is thirty-one seconds. Seven data …
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An intensive study of the currents and general hydrology of an anomalous upwelling area off South West Africa
The currents, winds and hydrology of a coastal site of approximately 120 square miles off South West Africa were studied intensively for two weeks during June/July 1978. Currents were measured by means of drogues tracked by RADAR from a central station at 45m of water depth. Classical inertial …
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Small-Scale Resuspension and Redistribution of Surface Sediments in the Northeast Gulf of Mexico
… gravitational processes and events of increased current speed in the deep ocean setting can result in recently deposited sediments to resuspend and be moved laterally with the current flow, increasing the area effected by the oil spill. Erosion experiments performed in a closed-loop resuspension …
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Operational profiling and statistical analysis of Arleigh Burke-class destroyers
… ship system selections. The most common is the speed-time profile, normally depicted as a histogram showing the percent of time spent at each speed. Many shortcomings exist in the current Arleigh Burke (DDG 51)-class operational profiles. The current speed-time profile is out of date, based on …
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Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations
The Agulhas Current is the strongest Western Boundary Current of the Southern Hemisphere and it plays a significant role in the circulation of the shelf and coastal waters, whereby mesoscale (50- 500 km) and submesoscale (1 -10 km) instabilities in the Agulhas Current impact the local oceanography …
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Storehouse of the Earth : to document the fast-changing environment
… so drastically as to cause damage to the Earth. Currently, as a consequence of accumulated modification, the rapidity of environmental change accelerates and causes hazards all over the world. Though the earth is always changing, the current speed of change is unprecedented and problematic. The …
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THE EFFECTS OF CURRENT BLOCKAGE ON OFFSHORE STRUCTURES
… in combined waves and an in-line steady current. Because of current blockage, the actual drag force experienced by such structures is over-predicted by the standard Morison equation and the present industry standard practice. A set of analytical models of current blockage is formulated …
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Developing an alternative means of assessing speed limits on rural single carriageway roads in Ireland using observed driver behaviour.
Speed limits in Ireland have undergone many changes since first introduced, most notably in 2005 when the State adopted metric speed limits. The challenge presented to the Department of Transport, Tourism and Sport and Local Authorities is to assess, manage and implement a system of speed limits …
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Dynamics of particle clouds in ambient currents with application to open-water sediment disposal
… examples include the land reclamation campaign currently underway in Singapore and the Boston Harbor Navigation Improvement Project. Both of these projects required the precise dumping of millions of cubic meters of purchased sediment, in the former example, and dredged material (both clean and …
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Splined Speed Control using SpAM (Speed-based Acceleration Maps) for an Autonomous Ground Vehicle
There are many forms of speed control for an autonomous ground vehicle currently in development. Most use a simple PID controller to achieve a speed specified by a higher-level motion planning algorithm. Simple controllers may not provide a desired acceleration profile for a ground vehicle. Also, …
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An application of ocean wave-current refraction to the Gulf Stream using SEASAT SAR data
When ocean waves in deep water interact with a current, the direction of propagation and characteristics of the waves such as height and length are affected. Swell in the open ocean can undergo significant refraction as it passes through major current systems like the Gulf Stream or Antarctic …
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Ice-ocean interactions beneath the north-western Ross Ice Shelf, Antarctica
… to the site. Tides account for half of the flow speed variance, and low frequency variability is influenced by local winds, and eddies associated with sea ice production in the polynya. Four years of basal melt rate observations show a mean melt rate of 1.8 m y$^{-1}$ at the mooring site and a …
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Impacts of coastal realignment on intertidal sediment dynamics: Freiston Shore, the Wash
… than the adjacent saltmarsh, causing high tidal current speeds as water flowed into the site and prolonged drainage of the site. This resulted in sheetflow over the intertidal flats, which caused an enhancement to the natural creek development. The water and sediment interaction between this …
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Towards Improved Estimates of Upper Ocean Energetics
… to the interaction between ocean surface currents and surface wind stress, a number of surface current decompositions can be used to decompose wind work calculations. In this research, geostrophic, ageostrophic, Ekman, and total current decompositions are all used to calculate wind work. …
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