Engineering Commons^™

Passive And Active Nonlinear Control Of Ship Roll Motions Using U-Tube Tanks, Thongchai Phairoh

Mechanical & Aerospace Engineering Theses & Dissertations

A U-tube water tank is first designed to roll a ship floating on still water. The 6-degree of freedom (DOF) dynamic model of U-tube tank is derived and the effects of its parameters on ship roll motion are studied. Numerical simulations show that the U-tube tank is an effective stimulator to roll the ship on still water. For a rolling ship, the U-tube tank can be used as a damper to reduce ship roll motion quickly.

Active control of ship roll motion with a proportional and derivative (PD) controller, linear quadratic regulator (LQR), generalized predictive control (GPC), and deadbeat predictive …

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 …

Wind-Induced Exchange In Semi-Enclosed Basins, Rosario Sanay

OES Theses and Dissertations

The wind-induced circulation over laterally varying bathymetry was investigated in homogeneous and in stratified systems using the three-dimensional Regional Ocean Model (ROMS). For homogeneous systems, the focus was to describe the influence of the earth's rotation on the lateral distribution of the flow with particular emphasis on the transverse circulation. Along-basin wind-stress with no rotation caused a circulation dominated by an axially symmetric transverse structure consisting of downwind flow over the shoals and upwind flow in the channel along the whole domain. Transverse circulation was important only at the head of the system where the water sank and reversed direction …

Laboratory Oxide Coatings: Physical Form And Surface Chemistry, Kea U. Duckenfield

Dissertations, Theses, and Masters Projects

The impact of dissolved trace metals on aquatic ecosystems and human health is controlled by sorption, i.e., binding to the surfaces of environmental particles. Since many environmental particles are coated with highly reactive substances, and since discrepancies in trace metal sorption behavior persist between oxides developed in the laboratory and environmental oxide phases, it was hypothesized that the physical form of oxide coatings may influence the chemical properties of the coated particle. Therefore, relationships between the physical forms of several different Fe(III) oxide coatings and the Cu(II) sorption behavior of the coated solids were investigated in comparison with the component …

Optimal Feedback Control For Ship Roll Motion Under Sea States, Anusit Anmanatarkul

Mechanical & Aerospace Engineering Theses & Dissertations

The primary influences of ship motion are roll motion. The purpose of this dissertation is to discuss a means to reduce the roll amplitude of ship motion in the case of zero forward speed using the roll mitigation device known as the flume tank, or U-tube, tank. Passive control and active control are studied. Optimal feedback control is the designated algorithm for activated roll mitigation device. The assumed model in this study is a submarine chaser. The linear coupled equation of swaying, rolling, and yawing motion of this assumed model is studied. The roll motion of this vessel is investigated …

Generalized Predictive Control Of Ship Coupling Motions Using Active Flume Tanks, Abdulkarim Mohammed Alotaiwi

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation uses the Generalized Predictive Control (GPC) approach to design a control system for a ship rolling motion coupled with the sway and yaw using an activated flume tank. GPC is a strategy based on system output prediction over finite horizon known as the prediction horizon. GPC controller is designed from the coefficients of the Autoregressive model with exogenous input (ARX) that are computed directly from input and output data. It computes the future control input based on the cost function with weighted input and output. System identification approach is implemented on the system to find the ARX coefficients …

Fish Cage Physical Scale Modeling, Michael J. Palczynski

Master's Theses and Capstones

Scale model tests were completed in the University of New Hampshire (UNH) Wave/Tow tank to determine the movements and forces on two different fish cage models. The results of the testing were used to validate a finite element analysis and also were scaled up to that of a full sized, deployed fish cage used for aquaculture purposes.

The first model was a “skeleton” cage (without nets) rectangular in shape. This model was moored submerged in front of a viewing window and subjected to various regular waves. The motions were then recorded nonintrusively by means of an optical system acting through …

Stratal Architecture In A Prograding Shoreface Deposit, Eastern Shore, Va: Relationship To Grain Size, Permeability, And Facies Distribution, Andrew C. Miller

OES Theses and Dissertations

A fundamental concern of the stratigrapher is to develop predictive models of stratigraphic organization. In sedimentology one of the most significant problems that has yet to be resolved is the fact that there is a lack of quantitative information regarding the relationship between geometry of beds, thickness of beds, grain size and sedimentary structures in sandy environments, especially shallow marine deposits. Scientists have also realized the need to correlate quantitative permeability to sedimentary structures and scales of stratigraphic organization. The purpose of the study is to investigate the scales of stratigraphic organization that control the variation of grain size and …

Nitrate Reduction At The Groundwater - Salt Marsh Interface, Craig -1967 Tobias

Dissertations, Theses, and Masters Projects

The influence of groundwater discharge on the hydrology and biogeochemical cycling of nitrogen in a fringing intertidal wetland was studied by characterizing groundwater discharge, determining N-cycling rates in cores, and examining nitrate reduction in situ using 15N enrichment and natural gradient tracer techniques. Groundwater discharge was estimated by three independent methods: Darcy's Law, a water/salt mass balance, and a subsurface tracer test. Seasonal patterns of discharge predicted by Darcy's Law and the mass balance were similar. Discharge maxima and minima occurred in April and September, respectively. The water/salt mass balance provided the more reasonable estimate of groundwater flux at high …

Ecosystem Analysis Of Water Column Processes In The York River Estuary, Virginia: Historical Records, Field Studies And Modeling Analysis, Yongsik Sin

Dissertations, Theses, and Masters Projects

Analyses of EPA long-term datasets (1985--1994) combined with field studies and ecosystem model development were used to investigate phytoplankton and nutrient dynamics in the York River estuary. Analysis of the EPA dataset showed that algal blooms occurred during winter-spring followed by smaller summer blooms. Peak phytoplankton biomass during the winter-spring blooms occurred in the mid reach of the mesohaline zone whereas during the summer bloom it occurred in the tidal fresh-mesolialine transition zone. River discharge appears to be the major factor controlling the location and timing of the winter-spring blooms and the relative degree of potential nitrogen (N) and phosphorus …

The Study Of Wave-Blocking And Current Effects On Nonlinear Interactions Of Shallow-Water Waves Using Advanced Boussinesq Models, Qin Chen

Civil & Environmental Engineering Theses & Dissertations

The first part of this work focuses on the derivation of enhanced Boussinesq-type equations for the combined motion of waves and currents in shallow water areas.

The strategy proposed in this work is to couple two known methods which are the sponge layer concept suitable for short waves and Sommerfeld radiation condition for currents. This coupling method provides satisfactory non-reflective boundaries for the simulation of fully coupled wave/current motion as demonstrated by the numerical experiments. We verify the model against the well known solutions based on the existing theories and good agreement has been observed. The numerical results confirm the …

A Design Of A Marine Radar Mast System For Minimum Vibration, Suey-Yueh Hu

Dissertations and Theses @ UNI

This experimental research focused on four areas: (a) the design of a new procedure for imitating the dynamic behavior of an electronic base plate on a radar mast system; (b) determination of a reasonable oscillation modal state; (c) avoidance of the destruction of the ability of the radar on the mast of a ship to receive and analyze incoming signals; and (d) design of a vibration absorber and vibration isolator based on an oscillation frequency. An adapted design for the vibration absorber and vibration isolator contributed to the prevention of excessive amplitude being produced by random forces acting upon a …

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.

Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen

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

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 …

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.

Characterization Of Anti-Tumor Immunity In Oyster Toadfish (Opsanus Tau), And The Effects Of 7,12 -Dimethylbenz(A)Anthracene On This Immune Response, Kenneth R. Seeley

Dissertations, Theses, and Masters Projects

Cell-mediated lysis of cultured tumor target cells by nonspecific cytotoxic cells (NCC) was examined in the oyster toadfish (Opsanus tau), an estuarine teleost. NCC activity was evaluated in cells taken from the head kidney, peripheral blood, spleen and peritoneal cavity. NCC activity was a property of plastic nonadherent cells which lacked phagocytic activity, indicating that in terms of their functional capacity, the cells which mediate nonspecific cytoxic immune responses in oyster toadfish do not appear to be monocytes or macrophages. However, light and electron microscopic examination of these cells revealed that morphologically, they resemble monocytes and macrophages. A new technique …

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

Dissertations, Theses, and Masters Projects

No abstract provided.

Recommendations For Amelioration Of Legal And Environmental Concerns About Mining Of Deepsea Deposits Of Polymetallic Sulfides, Michael P. De Luca

Dissertations, Theses, and Masters Projects

No abstract provided.

Late Cenozoic Landforms, Stratigraphy And History Of Sea Level Oscillations Of Southeastern Virginia And Northeastern North Carolina, Pamela Crowson Peebles

Dissertations, Theses, and Masters Projects

A depositional model accounting for the stratigraphic sequences which accumulate during a marine transgression across a dissected coastal plain aids in understanding the geologic history of southeastern Virginia and northeastern North Carolina. Application of this model to the Shirley Formation (middle Pleistocene) and the Sedgefield and Lynnhaven members of the Tabb Formation (late Pleistocene) allows delineation of (1) the facies within, (2) the areal extent of, and (3) the landforms associated with these lithostratigraphic units. Facies within each lithostratigraphic unit consist of (1) a vertical succession from local, basal, channel-fill deposits and coarse, basal, lag deposits which grade upward into …

Water Wave Refraction With Non-Linear Theory, Im Sang Oh

OES Theses and Dissertations

Two different kinds of wave refraction models are formulated in the present study using Stokes' third order wave theory. One type of model is utilized in a parametric study employing several different topographies. Wave trajectories obtained from this model, when obtained by using first and third order wave theory with and without the consideration of energy dissipation, show considerable differences. These differences are examined in more detail for a bottom of constant slope: (1) An approximate 10% difference occurs between the refraction coefficients obtained using the first and the third order wave theory. (2) Considerably different ray trajectories are detected …