Physical Sciences and Mathematics Commons^™

Hydrogeology And Water Budget Analysis Of Two Interdunal Ponds Nags Head Woods Ecological Preserve, Dare County, North Carolina, Richard A. Hisert

OES Theses and Dissertations

Ground-water-fed interdunal ponds in Nags Head Woods Ecological Preserve lose as much as 7600 m³ yr^-1 of water through evaporation. This withdrawal of groundwater is sufficient to significantly alter flow patterns through the surficial aquifer on Bodie Island, N.C. Statistical analyses of evaporation estimates derived by various methods indicate a weak correlation, (r²=0.4-0.5) between pan evaporation data from Aurora, N.C. and pond evaporation at Nags Head Woods calculated by water budget analyses.

Results of stratigraphic and pedologic analyses in and around the ponds indicate that the ponds formed after development of multiple generations of dunes. This …

Trace Metals And Pyrite In Sediments Of Chesapeake Bay, Robert S. Kluckhohn

OES Theses and Dissertations

The formation and cycling of iron sulfides within anoxic sediments can affect the cycling of trace metals. The sediments at station CB-27 (near Annapolis, Maryland) in Chesapeake Bay were rich in FeS (39% of TS), low in greigite (3.6% of TS), and has a relatively constant pyrite concentration (50 - 60% of TS) with depth. The percent composition of total metals in pyrite were 25.7% cu, 11.8% Zn, 15.8% Fe, and non-detectable to 2.1% Cd. At Station CB- 28 (near the Choptank River), the sediments were low in FeS (1.7% of TS), richer in greigite (up to 14% of TS), …

The Effects Of Two Polycyclic Aromatic Hydrocarbons Benzo[A]Pyrene And Naphthalene On Reproductive Success Embryological Development Larval Physiology And Mortality Of The Mud Crab Rhithropanopeus Harisii (Gould), Gregory V. White

OES Theses and Dissertations

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and benzo[a]pyrene (B[a]P) are common in the water column and sediments of estuarine and coastal areas. The mud crab Rhithropanopeus harrisii was exposed to varying concentrations of Nap or B[a]P to determine the effects on reproductive success, embryological development, larval physiology and mortality. Nap and B[a]P decreased hatching success and prolonged embryological development. Both pollutants produced high abnormality frequencies for egg exposed larvae. Molt frequency and respiratory rates of larvae from non-exposed eggs were more chronically affected by these pollutants than were egg exposed larvae. The EC₅₀ concentrations were determined for …

The Hydrogeology And Leachate Generation Of An Alum Sludge Lagoon Chesapeake Virginia, Charles M. Darling

OES Theses and Dissertations

In 1986 the City of Chesapeake, Virginia began to dig shallow ponds ("lagoons") to contain alum sludge, a waste generated by the City from the process of treating potable water. Borings at the disposal site reveal that the near-surface geologic units include a thin mud-rich facies which overlies a thick sandy facies, both of which are in the Lynnhaven Member of the Tabb Formation. At 7 meters depth, a clay-rich facies of the Yorktown Formation (Morgarts Beach Member?) underlies the sandy water table aquifer. Water levels from twenty observation wells and two monitoring wells installed into the water table aquifer …

The Fokker-Planck And Related Equations In Theoretical Population Dynamics, George Derise

Mathematics & Statistics Theses & Dissertations

The population growth of a single species is modeled by a differential equation with initial condition(s) so that the number of organisms in the population is derived using some mechanism of growth, i.e. a growth rate function. However, such deterministic models are often highly unrealistic in population dynamics because population growth is basically a random event. There are a large number of chance factors influencing growth that might not be taken into account by deterministic models. The effect of other species (for example, in the chance meeting of a predator), population fluctuations due to weather changes that would alter food …

A Potentiometric Gaseous Hydrogen Sensor, Anne Guillory

Chemistry & Biochemistry Theses & Dissertations

The development of a potentiometric gaseous hydrogen sensor using a 75% palladium - 25% silver alloy as a selectively hydrogen permeable electrode is described. The sensor showed some promise when used with a molten base electrolyte. Other electrolytes are investigated at ambient and higher temperatures. Various cell designs including a platinum/silver-silver chloride sensor with a gel electrolyte are discussed.

The Study Of Oxygen Transport Through Polycrystalline, Single Crystal And Alloyed Silver, Dongchuan Wu

Physics Theses & Dissertations

The permeation of oxygen through large grain polycrystalline silver, through the (110), (111) and (100) single crystals of silver and through Ag0.05Zr alloy have been studied over the temperature range of 400 - 800 °C. In addition, studies were also conducted using glow discharge dissociation of the supply side ( upstream ) molecular oxygen in order to examine whether normal dissociative adsorption is a limiting step in the overall transport process.

The permeability of oxygen through polycrystalline silver was found to be quite linear and quite repeatable. The diffusivity measurements were found to exhibit two distinct linear regions, one above …

A Mathematical Model Of The Dynamics Of An Optically Pumped Codoped Solid State Laser System, Thomas G. Wangler

Mathematics & Statistics Theses & Dissertations

This is a study of a mathematical model for the dynamics of an optically pumped codoped solid state laser system. The model comprises five first order, nonlinear, coupled, ordinary differential equations which describe the temporal evolution of the dopant electron populations in the laser crystal as well as the photon density in the laser cavity. The analysis of the model is conducted in three parts.

First, a detailed explanation of the modeling process is given and the full set of rate equations is obtained. The model is then simplified and certain qualitative properties of the solution are obtained.

In the …

Seasonal And Diel Patterns Of Abundance And Productivity Of Phototrophic Picoplankton In The Lower Chesapeake Bay, Lewis Francis Affronti Jr.

Biological Sciences Theses & Dissertations

This study was performed to evaluate phototrophic pico-plankton (0.2 to 2.0 μm) dynamics within the lower Chesapeake Bay. A 15 month study of phototrophic picoplankton abundance and productivity was made from June 1988 to October 1989. Annual picoplankton abundance using epifluorescence microscopy ranged from 7.26 x 10⁶ cells/1 in the winter to 9.28 x 10⁸ cells/1 during late summer.

In situ incubations of natural picoplankton populations over the 15 month study were used to test the applicability of the frequency of dividing cells technique in estimating phototrophic picoplankton growth rates. The regression equation o fμ = 2.37 x …

The Role Of Longshore Sediment Transport In The Loss Of Fill Material From An Estuarine Groin System, R. Neville Reynolds

OES Theses and Dissertations

The influence of shoreline structures on longshore sediment transport and the evolution of a stable beach planform was investigated at Willoughby Spit, Virginia following the placement of 410,590 cubic meters of beach fill within a groin system. Shoreline changes and wave conditions in a single groin compartment, and the growth rate of a downdrift terminal spit were monitored during 1985 and 1986. Short term fluctuations in the shoreline position within the groin compartment suggested an episodic westerly movement of sediment through the groin system. Primary sediment moving events were associated with northerly winds which produced waves up to 50 cm …

Metal Mobilization From A Near-Shore Lake Sediment Under Simulated Acidic Groundwater Inputs, Raveendra V. Ika

OES Theses and Dissertations

Simulation of acidic groundwater passing through lake sediments was conducted under controlled conditions in a laboratory. Three sediment cores collected intact from the near-shore region of an acidic lake were subjected to simulated groundwater inputs of initially identical chemistry for a seven day period. Following this period water being used in the simulation for two of the sediment cores was acidified by hydrochloric acid (HC1) addition to examine the ability of these sediments to neutralize acidic groundwater with varying H⁺ concentration.

Simulated acidic water passing through the sediment cores mobilized significant amounts of metals. The sediment acted as a …

A Root Finding Algorithm For Parallel Architecture Machines, Stuti Moitra

Computer Science Theses & Dissertations

In this thesis a parallel algorithm for determining the zeros of any given analytic function is described. Parallelism is achieved by modifying the traditional bisection algorithm for architecture machines.

Given any user supplied function f(X), continuous on the interval A_o ≤ x ≤ B₀, and the tolerance of accuracy an algorithm of determining up to ten roots, with error of approximation less than or equal to tolerance, on parallel systems like Distributed Array Processor (OAP) and N-cube is considered.

A variation of the bisection method has been adapted for this purpose. At each level of iteration a …

The Reaction Of Organoboranes With N-Chloro-N-Sodiocarbamates: A Convenient Synthesis Of N-Alkylcarbamates, Nanette M. Wachter-Jurcsak

Chemistry & Biochemistry Theses & Dissertations

N-alkylcarbamic acid esters are used extensively as fungicides, herbicides and pesticides. Industrial methods of preparation employ highly toxic reagents in their synthesis. Convenient and safe alternative methods are necessary.

Organoboranes are electrophilic compounds which can be employed as a source of alkyl substituents. They have been shown to successfully transfer alkyl groups to the nitrogen of chloramines. N-Alkylation of carbamic acid esters by reacting the corresponding N-chloro-N-sodiocarbamate with a variety of trialkylboranes is described. The yields of the various N-substituted products are discussed.

Two synthetic methods were devised. Originally, an equivalent of the isolated N-chlorocarbamate salt was added to the …

Boundary Value Problems In Elasticity And Thermoelasticity, Stuart Davidson

Mathematics & Statistics Theses & Dissertations

In this dissertation the author solves a series of mixed boundary value problems arising from crack problems in elasticity and thermoelasticity. Using integral transform techniques and separation of variables appropriately, it is shown that the solutions can be found by solving a corresponding set of triple or dual integral equations in some instances, while in others the solutions of triple or dual series relations are required. These in turn reduce to various singular integral equations which are solved in closed form, in two cases, or by numerical methods. The stress intensity factors at the crack tips, the physical parameters of …

The Truncated Cauchy Distribution: Estimation Of Parameters And Application To Stock Returns, Paul G. Staneski

Mathematics & Statistics Theses & Dissertations

The problem addressed in this dissertation is the existence and estimation of the parameters of a truncated Cauchy distribution. It is known that when a number of distributions with infinite support are truncated to a finite interval that the maximum likelihood estimator of the scale parameter fails to exist with positive probability. In particular, necessary and sufficient conditions which give rise to instances of non-existence have been found for the exponential (Deemer and Votaw (1955)), gamma (Broeder (1955), Hegde and Dahiya (1989)), Weibull (Mittal and Dahiya (1989)) and normal distribution (Barndorff-Nielsen (1978), Mittal and Dahiya (1987), Hegde and Dahiya (1989)). …

A Comparison Of Metals In Several Ahermatypic Corals And Surficial Sediments: Mobile Pinnacles And Hoffa Reef, Northcentral Gulf Of Mexico, Kathryn M. Conko

OES Theses and Dissertations

Metal concentrations in marine sediment and carbonate secreting invertebrates are representative of surrounding environmental chemistry. Aluminum, Ba Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, and Zn were measured in carbonate and terrigenous phases of the $<$63 um fraction of sediment samples from two locations in the northcentral Gulf of Mexico. Enrichment factors indicate that Al, Ba, Cu, Cr, Mg, Mn, and Ni are all slightly depleted in these sediments relative to crustal abundances. Discriminant function analyses shows that the concentrations of five elements differ between locations.

Ahermatypic coral (106 specimens) from five genera collected from the study sites were analyzed for Cd, Cu, Cr, Pb, Zn, Mn, Sr, Ba, Fe, Ca and Mg. Eight elements vary between some genera, Al and Ba also vary in concentration in corals between either location. All elements except Sr are significantly depleted in the coral with respect to Ca in the …

The Role Of The Voltage Gradient In The Agarose Gel Electrophoresis Of Dna, David Wheeler

Theses and Dissertations in Biomedical Sciences

In Part I of this dissertation, empirical equations for predicting DNA mobility during agarose gel electrophoresis (AGE) from voltage gradient are developed from the data of McDonnel (36) for electrophoresis in a 1.6% agarose gel. These equations represented the data well for DNA between 2 and 10 kilobase pairs (KBp) in length. A computer program, called GELSIM, which incorporates these equations is described in Part II. GELSIM was designed to allow researchers to analyze electrophoresis data by predicting the effect on DNA migration of altering the voltage of electrophoresis. In this way, electrophoretic banding patterns produced using different voltages could …

A Pulse Gas Chromatographic Method For Determining The Dispersion And Surface Area Of Co Oxidation Catalysts, Susan Kay Ohorodnik

Chemistry & Biochemistry Theses & Dissertations

Catalysts composed of platinum and/or palladium on tin(IV) oxide supports with or without silica gel have been developed for the recombination of carbon monoxide and oxygen to form carbon dioxide for use in carbon dioxide lasers. A pulse gas chromatographic method has been developed to measure the chemisorption properties of the catalysts. From the chemisorption measurements, the active surface area and dispersion of the catalysts have been determined.

A Generalization Of Linear Multistep Methods, Leon Arriola

Mathematics & Statistics Theses & Dissertations

A generalization of the methods that are currently available to solve systems of ordinary differential equations is made. This generalization is made by constructing linear multistep methods from an arbitrary set of monotone interpolating and approximating functions. Local truncation error estimates as well as stability analysis is given. Specifically, the class of linear multistep methods of the Adams and BDF type are discussed.

Performance Improvements For Fddi And Csma/Cd Protocols, David Earl Game

Computer Science Theses & Dissertations

The High-Performance Computing Initiative from the White House Office of Science and Technology Policy has defined 20 major challenges in science and engineering which are dependent on the solutions to a number of high-performance computing problems. One of the major areas of focus of this initiative is the development of gigabit rate networks to be used in environments such as the space station or a National Research and Educational Network (NREN).

The strategy here is to use existing network designs as building blocks for achieving higher rates, with the ultimate goal being a gigabit rate network. Two strategies which contribute …

An Extension Of Essentially Non-Oscillatory Shock-Capturing Schemes To Multi-Dimensional Systems Of Conservation Laws, Jay Casper

Mathematics & Statistics Theses & Dissertations

In recent years, a class of numerical schemes for solving hyperbolic partial differential equations has been developed which generalizes the first-order method of Godunov to arbitrary order of accuracy. High-order accuracy is obtained, wherever the solution is smooth, by an essentially non-oscillatory (ENO) piecewise polynomial reconstruction procedure, which yields high-order pointwise information from the cell averages of the solution at a given point in time. When applied to piecewise smooth initial data, this reconstruction enables a flux computation that provides a time update of the solution which is of high-order accuracy, wherever the function is smooth, and avoids a Gibbs …

The Effects Of Variable Parameters On The Behavior Of Initial Wind Waves, Glen Harvey Wheless

OES Theses and Dissertations

The generation mechanism of short wind waves is generally thought to be a viscous instability at the air-sea interface. The short, regular waves arising from a sudden wind on a still water surface have a dispersion relation which is characteristic of gravity-capillary waves. The effects of variable surface tension, viscosity and shear flow parameters on the behavior of these waves were studied.

A numerical hydrodynamic stability analysis of a coupled laminar shear flow was accomplished by integrating a transformed version of the Orr-Sommerfeld equation, subject to the boundary conditions at a two-fluid interface. Unbounded growth problems usually encountered in a …

Middle Eocene Foraminifera From The Piney Point Formation Of The Virginia And Maryland Coastal Plain, Megan S. Jones

OES Theses and Dissertations

This study examines the foraminiferal fauna, both benthic and planktonic, of the outcropping (45 samples) and subsurface (31 samples) middle Eocene Piney Point Formation in Virginia and Maryland. The primary objective of this study is to further refine the depositional history of the Salisbury Embayment which is represented by the middle Eocene Piney Point Formation. Ninety-six species of benthic and planktonic foraminifera were identified in this study. Of these, several are characteristic of the middle Eocene: Asterigerina texana, Hanzawaia danvillensis, Ceratobulimina exima, Cibicides westi, Chiloguembelitria columbiana, C. stavensis, Testacarinata inconspicua and Pseudohastigerina wilcoxensislmicra. While these were relatively abundant, diagnostic middle …