Physical Sciences and Mathematics Commons^™

Sufficiency Of A Numerical Downstream Continuation, Charlie H. Cooke

Mathematics & Statistics Faculty Publications

(First paragraph) Customarily one does not impose n-th order boundary conditions on the solution of initial/boundary value problems whose characterizing partial differential equations are also n-th order. However, conjecture that such problems are not well-posed, or that a solution might not exist, is not always justified [l]. Perhaps a physically more natural example is provided by problems of computational fluid dynamics. Here boundary conditions which correctly should be applied at an infinite distance downstream from the region of interest are for computational convenience often applied at a finite location [2]. Results of numerical experimentation on viscous flows governed by …

Note: On Summability And Positive Linear Operators, J. J. Swetits

Mathematics & Statistics Faculty Publications

Quantitative estimates for approximation by positive linear operators are obtained with the use of a summability method which includes both convergence and almost convergence.

Spring Phytoplankton Composition And Distribution In Coastal Waters Between Nova Scotia And The Chesapeake Bay, Larry William Neal

OES Theses and Dissertations

This investigation was directed toward satisfying a recognized lack of informat on regarding phytoplankton composition and density in shelf waters between Nova Scotia and the Chesapeake Bay. A sedimentation technique was used in determining the phytoplankton composition of 99 samples collected between 2 March and 3 April 1971. Chlorophyll-a samples collected concurrently were analyzed fluorometrically. Simple correlation analyses were utilized in describing distributional patterns of phytoplankton density and chlorophyll-a concentration with respect to water temperature, salinity, density, depth, distance from shore and latitude. Analysis of variance was employed in assessing regional differences in phytoplankton density and chlorophyll-a.

The phytoplankton flora …

The Distribution Of Several Metals And Cation Exchange Capacity In Sediment Fractions From An Artificial And Natural Marsh, James River, Virginia, William Nivens

OES Theses and Dissertations

In order to examine the mechanisms by which Fe, Mn, Ca, Zn, Cu, Ni and Pb are bound in sediments, a sequential selective extraction procedure was employed on sediment samples collected at an experimental dredge disposal marsh and a neighboring natural marsh located near Windmill Point, James River, Va. The metal concentrations were determined in six phases, interstitial water, exchangeable, easily reducible (oxides of Mn), organic, moderately, reducible (oxides of Fe), and residual fractions. In addition, the cation exchange capacity (CEC) of the sediments was determined as well as the actual role of organics and colloidal iron coatings as they …

Mercury, Copper, And Zinc In Selected Ichthyofauna Of Lower Chesapeake Bay And Hampton Roads, Virginia, W. Bruce Aitenhead

OES Theses and Dissertations

Anchovys, croaker, spat, summer flounder and hogchokers were collected monthly to seasonally from November 1972 to October 1973 at three locations in the southern Chesapeake Bay region of Virginia.

The concentrations of mercury, copper and zinc were determined by atomic absorption spectrophotometry in whole fishes. Metal concentration varied with species and location. Anchovys had the highest mean concentrations of mercury and zinc while hog- chokers had the highest mean copper concentration. Mercury levels exceeding O.5 ppm were observed in species from all three loca- tions, but maximum heavy metal concentrations per species were highest in Craney Island fishes.

Temporal variations …

Conservation According To The Pure Theory Of Exhaustible Resources, George Lymbouris

Economics Theses & Dissertations

The objective of this thesis is to develop a theory for defining optimal conservation and applying definition to the prevailing rate of domestic petroleum production. Optimal conservation is defined as action designed to achieve or to maintain, from the point of view of society as a whole, the maximum present value of natural resources (or of a natural resource). The proper "action" is defined according to the pure theory of exhaustible resources. The literature survey is a chronological series of articles concerning this theory.

Through building a model which shows that optimal conservation occurs when the marginal internal rate of …

Experiments In Attempted Interspecific And Interpopulational Hybridzation Of Grass Shrimp Of The Genus Palaemonetes (Caridea Palaemonidae), Mark Andrew Boston

OES Theses and Dissertations

The present study investigates the interfertility of Palaemonetes populations, Interspecific crosses were attempted between representatives of sympatric :populations of P. pugio, P. vulgaris, and P. intermedius, Intraspecific crosses were undertaken between geographically separated :populations of P. pugio. Laboratory conditions of 25°c, 25°/oo, and 14.5 hour photoperiod per day were maintained for all breeding attempts, Under these conditions interspecific hybridization of Palaemonetes pugio and P. vulgaris was not feasible. P. intermedius could not be hybridized with P. pugio and P. vulgaris. At 40 days of age P. pugio juveniles were significantly larger than P. vulgaris juveniles of …

The Response Of An Idealized Continental Shelf To Atmospheric Forcing, Paul Francis Moersdorf

OES Theses and Dissertations

The response of continental shelf water to cooling and wind stress is investigated using a two-dimensional numerical model. The topography of the east coast continental shelf was idealized by connecting a shallow (50 m) rectangular nearshore basin to a deeper (100 m) rectangular offshore basin. Numerous cases were examined using a wide range of values for both the air•sea temperature difference and the Wind speed, although the direction of the wind was always perpendicular to the coast.

The model predicts large excursions of shelf water offshore, and the subsequent surfacing of lower waters. Upwelling velocities of close to five meters …

The Photosynthetic Action Spectra Of The Phytoplankton And Their Role In Governing Spatial And Temporal Distribution: A Numerical Modeling Approach, William Morrow Willis

OES Theses and Dissertations

In the present study a numerical modeling approach is employed to examine the role of division spedific differences in photosynthetic action spectra in governing the relative size of diatom and dinoflagellate carbon synthesis along various marine light regime gradients. A radiative transfer model taking into account both Rayleigh and Mie atmospheric optical properties is employed to define the light regime incident on the sea surface. The hydrospheric light regime is defined by an exponential decay model with a correction for diffuse back scatter. Taken together, the atmospheric and hydrospheric models define the spectral composition and intensity of light in the …

The Chemical And Biological Effect Of A Gulf Stream Intrusion Off St. Augustine, Florida, Larry P. Atkinson, Gustav-Adolf Paffenhöfer, William M. Dunstan

CCPO Publications

During a 3-day anchor station in shelf waters off St. Augustine, Florida we observed the effect of an intruding mass of deeper Gulf Stream water. The shelf waters were relatively low in nutrients and salinity while the Gulf Stream waters were high in salinity and nutrients. Onshore currents correlated with increases in nitrate and chlorophyll concentrations.

The advection of higher nutrient Gulf Stream water coincided with high chlorophyll (∼ mg chl a m⁻³) concentrations and dense populations of Phaeocystis pouchetii (up to 3.12 × 10°1⁻¹). Zooplankton sampling was impossible in the bottom layer because of the …

The Results Of Four Oceanographic Cruises In The Georgia Bight, L. P. Atkinson

CCPO Publications

During 1973 and 1974 we conducted four oceanographic cruises in the Georgia Bight with the purpose of gaining background seasonal data with which to plan more scientific experiments. In this technical report the data are presented in graphical form with interpretation. The data itself was published in two technical reports (Atkinson, 1975 and 1976). Some of the interpretations in this report will be given in more detail in published journal articles.

The Relationship Of Bottom Sediments To The Current-Generated Topography On Crumps Bank And Willoughby Bank, Southern Chesapeake Bay, Virginia, Eugene Robert Brush

OES Theses and Dissertations

Crumps Bank and Willoughby Bank in Southern Chesapeake Bay are an area of varying topography. The area is bounded by two large bridge-tunnel spans, the dredged Thimble Shoal Channel borders it to the north, and the Ocean View section of Norfolk, Virginia lies to the south. The purpose of this investigation is to determine the relationship of the bottom sediments of Crumps Bank and Willoughby Bank.to the current-generated topography, and that this topography is the result of tidal currents.

The bathymetry, bottom sediment characteristics, bottom tidal currents, and the correlation of depth to various sediment parameters were examined to determine …

Complementary Extremum Principles, J. Swetits, C. Rogers

Mathematics & Statistics Faculty Publications

Important complementary extremum principles are generated without recourse to general variational theory. The results are illustrated by an application to a class of boundary value problems in Magnetohydrodynamics.

Approximation By Discrete Operators, J. J. Swetits, B. Wood

Mathematics & Statistics Faculty Publications

A discrete, positive, weighted algebraic polynomial operator which is based on Gaussian quadrature is constructed. The operator is shown to satisfy the Jackson estimate and an optimal version is obtained.

A Study Of The Gas-Solid Reaction Between Hydrogen Sulfide And Mercury(I) Chloride; Development Of A Method For Determination Of Atmospheric Hydrogen Sulfide, Eric H. De Carlo

Chemistry & Biochemistry Theses & Dissertations

The possibility of measuring hydrogen sulfide indirectly by measuring the mercury evolved from the gas-solid reaction between hydrogen sulfide and mercury(I) chloride was studied. DMCS treated glass wool was coated with mercurous chloride and used as a conversion material. The response to hydrogen sulfide was studied as a function of concentration and temperature. The possible interference of other sulfur gases and water was examined.

The studies indicated that hydrogen sulfide could be determined at concentrations as low as 15 ppb. It was found that mercaptans would actively interfere with the hydrogen sulfide to mercury conversion, but that sulfur dioxide would …

Description Of The Larval Development Of Squilla Empusa Say (Crustacea Stomatopoda) With Aspects Of Larval Ecology In Chesapeake Bay, Steven Gaines Morgan

OES Theses and Dissertations

Larvae of Sguilla empusa were collected from the plankton and were reared in the laboratory to describe the pelagic larval development and the postlarval stage. Nine pelagic stages are passed through before the postlarval stage is attained.

The larvae reared for descriptive purposes were subjected to sixteen combinations of temperature and salinity to determine their tolerance to the two parameters. Larvae survived longer and molted more frequently when reared at 25°/oo and 20°C or 25°C, which corresponds to the natural conditions of the Chesapeake Bay when the larvae were collected.

A three year planktonic survey conducted in the lower region …

Suspended Matter And Light Attenuation In A Turbid Estuary, Daniel E. Campbell

OES Theses and Dissertations

A study was made in Hampton Roads, Virginia, to characterize the suspended matter and to investigate its relationship to the light attenuation coefficient. The study gives a detailed description of the seston and its variations with time and space. An evaluation of the light attenuation coefficient as an indicator of seston distributional parameters was made.

The distribution of the suspended matter is obtained through gravimetric, Coulter counter and microscopic analyses. Microscopic analysis is employed to determine the composition of the seston and ATP determinations give the amount of living biomass. The suspended matter is characterized in terms of weight, numbers, …

A Seasonal Study Of Phytoplankton Composition Abundance And Productivity In Back Bay, Virginia, Robert Ringgold Comegys

Biological Sciences Theses & Dissertations

Phytoplankton samples were collected monthly (August 1974-June 1975) at two stations in the Back Bay system of southeastern Virginia. Measurements of phytoplankton productivity and potentially influencing environmental parameters (water and air temperature, turbidity, depth, pH, salinity, dissolved oxygen) accompanied sample collections. A total of 106 phytoplankton species, representing six algal divisions and 54 genera were identified. Cyanophyta species were dominant at both stations in the warmer months of August, September, October, and June, and in April at one station only. In all remaining months, Chlorophyta species were dominant, indicating a seasonal shift in phytoplankton composition during winter and spring. The …

Sediment Interstitial Dissolved Mercury And Carbon Relationships In An Artificial And Natural Marsh, James River, Virginia, Apostolos Katsaounis

OES Theses and Dissertations

Thirty six sediment cores were collected during August, 1976 and January, 1977 in order to examine the relationships between dissolved organic carbon and total dissolved mercury in the interstitial water of two marshes located near Windmill Point, James River, 16 km downstream from Hopewell, Virginia. The Windmill Point marsh development site is a dredged material disposal island in the James River. The reference marsh which does not contain dredged material, is located 2.3 km upstream at Ducking Stool Point.

The concentrations of dissolved organic carbon and total dissolved mercury showed no significant difference between the two marshes. Trends in the …

Static Temperature Measurements In Supersonic Flow Using Lasar Raman Spectroscopy, Paul A. Nystrom

Mechanical & Aerospace Engineering Theses & Dissertations

Laser Raman spectroscopy is a nonintrusive technique which can generate mean static temperature (MST) data within flow fields. By ratioing two simultaneously gathered portions of the Raman scattered spectrum, absolute intensity measurements were not needed. This method was applied to a supersonic cold air jet, where the NST ranged from 160'K to 300'K. Accurate measurements were not realized due to the presence of flow contaminates, especially water vapor.

The Effects Of Electron Irradiation On Mosfets, Mark D. Skeldon

Physics Theses & Dissertations

The characteristics of n and p-channel MOSFETs have been investigated while irradiated with electron radiation from Strontium 9Ø. The drain current vs. gate voltage of the p-channel MOSFET and the threshold voltage changes in n and p-channel MOSFETs have been studied with and without aluminum shielding. The switching characteristics and threshold voltage changes of COS/MOS dual input NAND gates have been investigated while exposed to electron radiation. Various methods of annealing the radiation damage to these devices is discussed.

Effect Of Nitrite And Nitrate On The Larval Development Of The Grass Shrimp Palaemonetes Pugio Holthuis, Carl Bingham Hinesman

OES Theses and Dissertations

The effects of nitrite and nitrate on survival and larval development of the grass shrimp Palaemonetes pugio were investigated in the laboratory. Nitrite concentrations assayed were 0 (control), 0.5, 1.0, 10, 25 and 50 mg NO₂/1. Nitrate concentrations tested were 0 (control), 100, 250, 500, 1000 and 2000 mg NO₃/1. Temperature and salinity conditions were 25 C and 25 ‰, respectively, and all tests occurred in the dark. Thirty-six larvae were reared in each assay, twelve from each of three adult females.

Nitrite levels of'5 and 50 mg NO₂/1 significantly reduced survival of larvae …

A Baseline Study On The Possible Mechanisms Of Larval Stomatopod Distribution On The Carolina Shelf, Carl Robert Berman Jr.

OES Theses and Dissertations

The South Carolina Marine Resources Institute provided the author with 198 station samples containing 2,193 stomatopod larvae. These larvae had been collected during ichthyoplankton Bongo tows on five separate cruises aboard the Institute's vessel R/V DOLPHIN (February, 1972 to January, 1975). The larvae were examined microscopically and divided into early, middle, and late stages according to known growth criteria. The larval distribution was plotted geographically, by seasons, and larval density (larvae/m3) was graphed against distance offshore. Using these data, together with the circulation characteristics on the Carolina Shelf, significant distributional data appeared which supported the hypothesis that the stomatopod population …

Temperature And Salinity Tolerance Of The Larvae Of The Sand Shrimp, Crangon Septemspinosa (Say), Karen Lyttle Hinsman

OES Theses and Dissertations

The effects of temperature and salinity on the larval development of the sand shrimp, Crangon septemspinosa, were investigated in the laboratory using 30 combinations of temperature and salinity in a five by six factorial experiment. The five temperatures were 5°c, 10°c, 15°c, 20°c, and 25°c and the six salinities were 10°/oo, 15°/oo, 20°/oo, 25°/oo, 30°/oo and 35°/oo. Thirty-six larvae were used for each temperature-salinity combination. Temperature and salinity produced significant differences (1% level) in survival and the duration of larval development. Highest survival occurred at 15°c and 20°/oo. At optimum temperatures (15°c to 20°c) larvae exhibited the broadest tolerance …

A Model To Investigate The Influence Of Suspended Sediment On The Mass Transport Of A Pollutant In Open Channel Flow, Raymond Scott Chapman

Civil & Environmental Engineering Theses & Dissertations

The environmental impact of the transport of pollutants in open channel flow has for many years been of interest due to the continuous introduction of heavy metals, pesticides, herbicides, and other foreign substances into natural waterways. In order to fully understand this transport process, it-is necessary to examine the significance of its individual components. In the present study an explicit two-dimensional finite difference model, designed to investigate the influence of suspended sediment on the pollutant transport process, is presented. Specific attention is directed toward examining the role of suspended sediment in 1) the turbulent vertical transport mechanism in a stratified …

Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley. Copyright © 1977 American Institute of Physics.

Modes Of Gulf Stream Intrusion Into The South Atlantic Bight Shelf Waters, Larry P. Atkinson

CCPO Publications

Consideration is given to the intrusion of Gulf Stream waters into the shelf waters of the South Atlantic Bight. It is observed that three modes of intrusion may occur, depending on particular ambient shelf water density. They are override, interleave, and bottom intrusion. It is noted that: (1) except in January, when the shelf water densities are relatively higher, 20°C Gulf Stream water can form a bottom intrusion anywhere along the coast, (2) Gulf Stream waters of 24°C can only form bottom intrusions from April to November, and (3) the rest of the year, 24°C waters interleave or override.

Solar Magnetoatmospheric Waves-A Simplified Mathematical Treatment, John A. Adam

Mathematics & Statistics Faculty Publications

The inhomogeneous wave equation for a special class of magnetoatmospheric waves is formally solved, and the principle of stationary phase used to provide information on the group velocity properties of such waves. General results are presented concerning the associated mechanical energy flux. The basic problem considered is relevant to waves initiated by sudden events in the solar atmosphere.

Feeding Ecology Of Black Sea Bass Centropristis Striata On An Artificial Reef Off Virginia (Perciforms: Serranidae), Ping K. Chee

OES Theses and Dissertations

The feeding ecology of the black sea bass, Centropristis striata, associated with artificial reefs shows seasonal and size-related changes. Monthly collections totaling 520 black sea bass taken from an artificial reef near the Chesapeake Light Tower, Virginia, between August 1975 and May 1976, were analyzed for food habits as revealed by number, volume, frequency of occurrence and a modified Index of Relative Importance.

The black sea bass feeds on the artificial reef as well as the adjacent areas. When food was abundant on the reef, food items from the reef and the surrounding area were consumed. Upon depletion of the …

The Effects Of Dredging On The Stability Of An Ebb-Tidal Delta, Lynnhaven Inlet, Virginia, Donald Keith Riggenbach

OES Theses and Dissertations

A channel was dredged in 1965 through the ebb-tidal delta of Lynnhaven Inlet, Virginia. The purpose of this study was to determine if this channel has affected the morphological configuration of the delta. It was proposed that the channel caused the dynamically stable delta to become unstable and change its morphology.

Bathymetric comparisons of seven surveys during the last 122 years, including one conducted during this investigation, show that prior to 1962 and the dredging operations, the delta had become dynamically stable. The present survey shows that the delta has changed its shape in response to the interaction of the …