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Full-Text Articles in Engineering
Modeling Flocculation And Deflocculation Processes Of Cohesive Sediments, Xiaoteng Shen
Modeling Flocculation And Deflocculation Processes Of Cohesive Sediments, Xiaoteng Shen
Dissertations, Theses, and Masters Projects
The transport and fate of cohesive sediments are responsible for many engineering, environmental, economic and policy issues that relate to, for example, siltation and dredging in navigation channels, water quality, water turbidity, pollutant transports, and biological ecosystem responses. Our current understanding, however, is insufficient to conduct accurate quantitative predictions of these processes. This is because the cohesive particles in natural waters will flocculate, which determines the settling, and thus the deposition behaviors. The simulation of flocculation processes is a primary challenge since the time variation of Floc Size Distribution (FSD) is controlled by a partial differential equation that also contains …
An Evaluation Of A Reduced Bar Spacing Turtle Excluder Device In The U.S Gulf Of Mexico Offshore Shrimp Trawl Fishery, Michel Anthony Nalovic
An Evaluation Of A Reduced Bar Spacing Turtle Excluder Device In The U.S Gulf Of Mexico Offshore Shrimp Trawl Fishery, Michel Anthony Nalovic
Dissertations, Theses, and Masters Projects
Shrimp are the most economically valuable internationally-traded seafood commodity, and wild-caught, trawled shrimp make up almost half of the ~6.6 million metric tons of annual global production. Shrimp trawling is responsible for one-third of the world’s total fisheries bycatch, leading many to consider shrimp trawling to be the single most destructive fishing practice in the world. Though the bycatch of large marine animals can be significantly reduced by use of turtle excluder devices (TEDs) on shrimp trawls, current TED designs are ineffective at reducing the capture of smaller organisms which represent a large portion of the total bycatch. To further …
Twine-Top Modifications Of Sea-Scallop Dredges: Reducing Yellowtail-Flounder Bycatch, Kelli A. Milleville
Twine-Top Modifications Of Sea-Scallop Dredges: Reducing Yellowtail-Flounder Bycatch, Kelli A. Milleville
Dissertations, Theses, and Masters Projects
No abstract provided.
Simulation Of Turbidity Maximums In The York River, Virginia, Jae-Il Kwon
Simulation Of Turbidity Maximums In The York River, Virginia, Jae-Il Kwon
Dissertations, Theses, and Masters Projects
Two of the most important processes in cohesive sediment transport, erosion rate and settling velocity, were the focus of this study. Settling velocities were estimated by the Owen tube method and the acoustic Doppler velocimeter (ADV) method. A novel erosion model, namely a constant erosion rate model, was implemented in a three-dimensional hydrodynamic eutrophication model (HEM-3D) to simulate the turbidity maximums in the York River system, Virginia. Two one-month periods of model simulations were conducted to mimic typical dry (November--December, 2001) and wet (March--April, 2002) seasons. In order to have enough data to verify the model, four slack water surveys …
Evaluating Restored Oyster Reefs In Chesapeake Bay: How Habitat Structure Influences Ecological Function, Janet A. Nestlerode
Evaluating Restored Oyster Reefs In Chesapeake Bay: How Habitat Structure Influences Ecological Function, Janet A. Nestlerode
Dissertations, Theses, and Masters Projects
A shortage of shell resources for restoring reefs of the Eastern oyster, Crassostrea virginica, has led to widespread use of substitute materials. The effectiveness of such alternative substrates as habitat for reef-associated fauna other than oysters is largely unresolved. I investigated the habitat value of oyster shell, surf clam (Spisula solidissima) shell, and pelletized coal ash reefs for benthic and nektonic communities. Oyster recruitment, survival, and growth were monitored on reefs of oyster and surf clam shell near the mouth of Chesapeake Bay and York River, USA. Oyster shell supported greater oyster growth and survival and offered the highest degree …
Gaseous Flux And Distribution Of Polycyclic Aromatic Hydrocarbons Across The Air-Water Interface Of Southern Chesapeake Bay, Kurt E. Gustafson
Gaseous Flux And Distribution Of Polycyclic Aromatic Hydrocarbons Across The Air-Water Interface Of Southern Chesapeake Bay, Kurt E. Gustafson
Dissertations, Theses, and Masters Projects
Gaseous fluxes of polycyclic aromatic hydrocarbons (PAHs) across the air-water interface of Southern Chesapeake Bay were calculated for the period January 1994 through May 1995 using a modified two-film model. Additionally, the distributions of PAHs between the vapor and aerosol phase in the atmosphere, and between the freely dissolved and suspended particulate phase in the water column were investigated. Net instantaneous gaseous fluxes of PAHs were determined to vary in direction and magnitude both spatially and temporally across the air-water interface of Southern Chesapeake Bay at four sites ranging from remote to urban and highly industrialized. The magnitude of gas …
Water Quality Modeling As An Inverse Problem, Jian Shen
Water Quality Modeling As An Inverse Problem, Jian Shen
Dissertations, Theses, and Masters Projects
An inverse mathematical estuarine eutrophication model has been developed. The model provides a framework to estimate unknown parameters by assimilation of the concentration data of those state variables. The inverse model developed is a laterally integrated, two-dimensional, real-time model which consists of a hydrodynamic model, an eutrophication model and an adjoint model. The hydrodynamic model provides the dynamic fields for both the eutrophication model and the adjoint model. The eutrophication model simulates eight water quality state variables which are phytoplankton, organic nitrogen, ammonium nitrogen, nitrite-nitrate nitrogen, organic phosphorus, inorganic (ortho) phosphorus, carbonaceous biochemical oxygen demand and dissolved oxygen. The adjoint …
Impact Of Artificial Reef Associates On Macrobenthic Community Structure In Florida Bay, Heinz Michael Proft
Impact Of Artificial Reef Associates On Macrobenthic Community Structure In Florida Bay, Heinz Michael Proft
Dissertations, Theses, and Masters Projects
No abstract provided.
Crassostrea Virginica On Constructed Intertidal Oyster Reefs: The Effects Of Tidal Height And Substrate Level On Settlement, Growth, And Mortality, Ian K. Bartol
Dissertations, Theses, and Masters Projects
No abstract provided.
Resuspension Behavior Of Natural Estuarine Sediments, Chang-Hee Lee
Resuspension Behavior Of Natural Estuarine Sediments, Chang-Hee Lee
Dissertations, Theses, and Masters Projects
The resuspension behavior of natural estuarine sediments was studied using the VIMS Sea Carousel, a benthic annular flume. The bed shear stresses produced by the flume were measured by a hot-film sensor mounted flush on the bottom of a laboratory version of the Carousel under a clear-water and flat-bottom condition. Measurements showed a reasonably uniform bed shear stress across the channel and agreed with the relationship &\tau\sb{lcub}\rm b{rcub}=0.011\Omega\sp{lcub}1.69{rcub},& where &\Omega& = ring speed (rpm) and &\tau\sb{lcub}\rm b{rcub}& = spatially-averaged bed shear stress (N/m&\sp2&), predicted from a previous numerical study. Thus, the &\tau\sb{lcub}\rm b{rcub}& was used as a bed shear stress …
Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen
Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen
Dissertations, Theses, and Masters Projects
No abstract provided.
Dynamics Of Fish Assemblages Associated With An Offshore Artificial Reef In The Southern Mid-Atlantic Bight, Aaron J. Adams
Dynamics Of Fish Assemblages Associated With An Offshore Artificial Reef In The Southern Mid-Atlantic Bight, Aaron J. Adams
Dissertations, Theses, and Masters Projects
No abstract provided.
Interspecific And Intraspecific Variability In Placoid Scale Morphology In Relation To Body Form Variability In Squaliformes, Christopher R. Tabit
Interspecific And Intraspecific Variability In Placoid Scale Morphology In Relation To Body Form Variability In Squaliformes, Christopher R. Tabit
Dissertations, Theses, and Masters Projects
An ontogenetic series of nine species; Centrophorus granulosus, Centroscymnus coelolepis, Dalatias licha, Deania calcea, Echinorhinus cookei, Isistius brasiliensis, Oxynotus centrina and Squalus acanthias were studied to determine swimming capabilities, boundary-layer flow conditions and placoid scale functional morphologies. Body morphometric variables included the girth and the distance from snout to the orbitals, origin of the median and paired fins, and the caudal peduncle, body and fin surface area, fin aspect ratios and caudal fin angles. Placoid scales were sampled from sixteen regions across the body. Morphometric variables included the number of scales per area of integument, scale crown width, length and …
Beach Forms Induced By Coastal Structures Forming Embayments In Fetch-Limited Environments, Jian Hua Li
Beach Forms Induced By Coastal Structures Forming Embayments In Fetch-Limited Environments, Jian Hua Li
Dissertations, Theses, and Masters Projects
No abstract provided.
The Effects Of Shading By Open-Pile Structures On The Density Of Spartina Alterniflora, Heather L. Mcguire
The Effects Of Shading By Open-Pile Structures On The Density Of Spartina Alterniflora, Heather L. Mcguire
Dissertations, Theses, and Masters Projects
No abstract provided.
Interaction Of Long Waves And Nearshore Barred Topography--A Mechanism Of Bar Migration, Chang-Shik Kim
Interaction Of Long Waves And Nearshore Barred Topography--A Mechanism Of Bar Migration, Chang-Shik Kim
Dissertations, Theses, and Masters Projects
It has been widely observed in nature that longshore bar topography changes profile in the onshore-offshore direction. It is common for some bars to migrate onshore during post-storm phases and offshore during storms. Although the behavior of submarine bars has been widely reported, its mechanisms and forcings are far less clear. to determine the mechanism for bar migration or for the persistence of bar systems, a numerical model is developed, which accounts for the mass transport velocities in the bottom boundary layer induced by a family of combined long waves at surf-beat frequencies and wind waves. The present approach simulates …
The Effects Of Petroleum On The Salt Marsh Ecosystem, James L. Lake
The Effects Of Petroleum On The Salt Marsh Ecosystem, James L. Lake
Dissertations, Theses, and Masters Projects
No abstract provided.