Physical Sciences and Mathematics Commons^™

Picosecond Laser Pulse Irradiation Of Crystalline Silicon, K. L. Merkle, H. Baumgart, R.H. Uebbing, F. Phillipp

Electrical & Computer Engineering Faculty Publications

Morphology changes introduced by picosecond laser pulses at λ = 532 nm and 355 nm in (111) and (100) silicon samples are studied by means of optical and high-voltage electron microscopy. Depending on energy fluence, orientation and wavelength, amorphous or highly defective regions may be created. From an analysis of damage thresholds and damage depth distributions it is concluded that melting and energy confinement precedes the formation of the structural changes.

An Evaluation Of Nutrient Sources To Onslow Bay, North Carolina, Larry P. Atkinson, Leonard J. Pietrafesa, Eileen E. Hofmann

CCPO Publications

Hydrographic and current meter data from Onslow Bay, North Carolina, were examined to determine the relative importance of various nutrient sources.

Upwelled Gulf Stream water is the major source of nutrients while rivers represent a minor, if not insignificant, source. In the summer during stratified conditions, the upwelled water penetrates across the shelf, but in the winter the upwelled water is restricted to the outer shelf. Nitrate flux across the 40 m isobath was calculated from continuous temperature and current records. Flux during the summer of 1976 was 2 μM m² sec^-1 which is considerably less than flux …

Organic N-Chloramines: Chemistry And Toxicology, Frank E. Scully, Jr., Maxwell A. Bempong

Chemistry & Biochemistry Faculty Publications

The stability of aqueous solutions of organic N-chloramines, suspected of contaminating chlorinated water, has been studied. Two factors influence the decomposition of solutions of N-chloropiperidine and N-chlorodiethylamine: a spontaneous decomposition and photodecomposition. Since solutions of these compounds are relatively long-lived, a need for an analytical method for their identification is discussed. A new method is described which involves reaction of organic N-chloramines with arenesulfinic acid salts. The method gives high yields of stable arenesulfonamides. Several toxicological studies of N-chloropiperidine are described. The compound is mutagenic by Ames assay in Salmonella typhimurium strain TA 100 and does not require metabolic activation …

Smallest Cubic And Quartic Graphs With A Given Number Of Cutpoints And Bridges, Gary Chartrand, Farrokh Saba, John K. Cooper Jr., Frank Harary, Curtiss E. Wall

Mathematics & Statistics Faculty Publications

For positive integers b and c, with c even, satisfying the inequalities b+1≤c≤2b, the minimum order of a connected cubic graph with b bridges and c cutpoints is computed. Furthermore, the structure of all such smallest cubic graphs is determined. For each positive integer c, the minimum order of a quartic graph with c cutpoints is calculated. Moreover, the structure and number of all such smallest quartic graphs are determined.

Local Lp-Saturation Of Positive Linear Convolution Operators, J. J. Swetits, B. Wood

Mathematics & Statistics Faculty Publications

Local L_p-saturation of positive linear convolution operators is investigated. Results are obtained for two important classes of operators previously studied by Bojanic, DeVore, Korovkin and the authors.

Unbounded Functions And Positive Linear-Operators, J. J. Swetits, B. Wood

Mathematics & Statistics Faculty Publications

The approximation of unbounded functions by positive linear operators under multiplier enlargement is investigated. It is shown that a very wide class of positive linear operators can be used to approximate functions with arbitrary growth on the real line. Estimates are given in terms of the usual quantities which appear in the Shisha-Mond theorem. Examples are provided.

Synthesis Of Dihydroisoquinolines And Tetrahydroisoquinolines, John J. Schlager

Chemistry & Biochemistry Theses & Dissertations

Dihydroisoquinolines and tetrahydroisoquinolines are compounds which possess a variety of pharmacological activities. New easier methods of synthetic manipulations of these structures is of constant interest in the pharmaceutical industry.

This paper describes a new three step method of preparing 1-alkyl- and 1-aryl-tetrahydroisoquinolines from a tetrahydroisoquinoline. The synthesis involves the N-chlorination of tetrahydroisoquinoline followed by dehydrohalogenation with potassium superoxide. The reaction products are the dihydroisoquinolines. Overall yields range from 85-96%. The unsubstituted, 1-methyl-, and 1-phenyl-J,4-dihydroisoquinolines have been formed. Organometallation of the unsubstituted dihydroisoquinoline provides the 1-substituted tetrahydroisoquinoline. The 1-benzyl-, 1-n-butyl-, 1-ethyl-, 1-methyl-, and 1-phenyl-1,2,J,4-tetrahydroisoquinolines were prepared. The use of Grignard and …

A Quantitative Description Of Migratory Behavior Of The Brown Shrimp (Penaeus Aztecus) With Applications In Fisheries Management, Anne Madolyn Babcock

OES Theses and Dissertations

A quantitative description of the migratory behavior of the brown shrimp, Penaeus aztecus, was established using the density approach. A theoretical time density was estimated by the proportion of catch and catch per boat hour NOAA-NMFS fisheries statistics collected in Pamlico Sound, the Neuse River, and Core Sound. A clear quantitative description of brown shrimp migratory timing is found in the time densities. The impact of various physical tactors on the progress of the fishery in time and space can be objectively evaluated by using the time density statistics as dependent variables in modeling efforts. The distributions also enable …

Algal Dynamics In A Cypress Stand In The Seasonally Flooded Great Dismal Swamp, Joseph A. Atchue Iii

Biological Sciences Theses & Dissertations

The dynamics of epiphytic algae and phytoplankton were studied at a cypress stand in the Great Dismal Swamp, Virginia. Mean epiphytic algal biomass was 19.9 g m^-2 and mean planktonic biomass was 3.4 g m^-2.Nutrient concentrations in the epiphytic algae and the litter were determined. The algae had mean concentrations of 1.67% and 0.18%. They were found to immobilize as much as 0.5 g N m^-2 and 0.06 g P m^-2. This suggests that the algae are important as nutrient conservers. The phytoplankton were composed primarily of Bacillariophyceae. They exhibited a more or less …

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 …

A Direct Formulation And Computer-Implementation Of A Symbolic Network Analysis Algorithm, Timothy James Knerr

Electrical & Computer Engineering Theses & Dissertations

An algorithm for the symbolic analysis of linear, time-invariant, active or passive networks is presented. The algorithm incorporates the best features of earlier numerical and topological methods of symbolic analysis. A hybrid set of equations is formulated for a closed linear graph and arranged in matrix form. A numerical evalu­ation procedure for the determinant of this hybrid matrix results in an efficient method of symbolic analysis. A proof of the algorithm based on determinant evaluation by a permutation product expansion provides insight into relationships with other methods of symbolic analysis. A computer program implementation of the algorithm is described and …

Experimental Investigation Of A Rectangular Surface Thermal Plume, Li-Cheng Chu

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental investigation of the three dimensional mean temperature distribution of a rectangular buoyant surface thermal plume has been conducted for a range of buoyancies, velocity ratios, Reynolds numbers, and for various turbulence generating screens in the crossflow. This study has been motivated by a concern about the applicability of laboratory model data for predicting prototype plume behavior.

A large scale model has been built to study a buoyant, rectangular surface thermal plume which enters at right angles to a constant temperature uniform crossflow of depth equal to that of the plume. A large water tank and flume with weir …

Petroleum-Utilizing Bacteria: The Biological Line Defense Against Oil Pollution, Steven W. Sokolowski

Biological Sciences Theses & Dissertations

A silica gel-petroleum (SGP) medium was developed which is reliable, approximately the same cost as that of the corresponding agar-based petroleum medium, and can be made sufficiently firm to use in streaking or the spread-plate technique. Advantages of the medium include: the incorporation of all of the major ions of seawater in accordance with Dittmar's Law (the salinity of which can easily be varied from 0 to 35 parts per thousand); a wide workable pH range (5.5 to 11.6); negligable pH drift(~ 0.2 pH units after 166 days); the elimination of all but negligable amounts of syneresis, the ability to …

A Technique For The Isolation And Identification Of Aliphatic Amines In Water, Peter Alan Drew

Chemistry & Biochemistry Theses & Dissertations

Small, aliphatic amines added to a basic, aqueous solution (16.2 L) at a concentration of 100 parts per billion were isolated by sorption on a small column of macroreticular resin. The amines were eluted with diethyl ether; the eluate concentrated, and the compounds separated and identified by gas chromatography. The efficiency of the recovery of a-nines ranged from 5 to 28%.

A protocol for derivatizing pyrrolidine and n-pentylamine in ether with fluorinated acylating agents was developed. The method was found to be adequate for the detection of approximately 13 micrograms of &-nines in concentrated ether extract.

Environmental water samples …

Growth And Recruitment Of Two Penaeids In The Bay Of St. Louis, Mississippi During 1979, Teresa C. Heaton

OES Theses and Dissertations

Juvenile brown (Penaeus aztecus, Ives) and white (Penaeus setiferus, Linnaeus) shrimp were collected from two stations of a nursery area in St. Louis Bay Mississippi, during May to October, 1979. Periods of shrimp recruitment and growth were determined to discern whether the concurrent environmental variables of salinity and temperature had an influence on shrimp abundance and yield. Growth estimates were obtained from length frequency measurements of trawl samples taken over a 24-h period per month from each station. An analysis of variance of length versus the variables of sex, month, station, time of day, salinity and …

Chemistry Of Organic N-Chloramines, Formation Of Arenesulfonamides By Derivatization Of Organic N-Chloramine With Sodium Arenesulfinate, Katherine F. Bowdring

Chemistry & Biochemistry Theses & Dissertations

Organic N-chloramines are recognized by-products of chlorinated water systems. Because of their chemistry, none have been isolated or identified.

This paper discusses a method for the derivatization of the organic N-chloramines based on a nucleophillic substitution mechanism. N-Chloro derivatives of amines of various structures were studied including primary and secondary aliphatic amines, as well as amino acids. The effect of the presence of other functional groups including aromatic and unsaturated systems was investigated.

Derivatization was done by three different methods, one involving derivatization of the pure N-chloramine, and two involving derivatizations of the N-chloramine generated in situ. Seventeen arenesulfonamides have …

High Performance Liquid Chromatographic Analysis Of Biogenic Amines, Thais Edwina Ahrendt Keegan

Chemistry & Biochemistry Theses & Dissertations

The objectives of this research were to develop a sensitive method for separation and quantitation of biogenic amines and to apply that procedure by monitoring neurochemical changes resulting from stimuli to the test system.

Primary aromatic amines were derivatized with o-phthalaldehyde-mercaptoethanol prior to chromatography, Separation of the fluorescent adduct was achieved using a μBondapak/ phenyl reversed-phase column and a two-step gradient of methanol:0.08 M acetic acid, pH J.O. Fluorescence was monitored using a J40 nm excitation energy and an emission filter which transmits radiation greater than 400 nm (50% T at 418 nanometers).

Following optimization of the chromatographic conditions, studies …

Characteristics Of Sediment Transport In Overwash Surges, Paul Richardson Bowen

OES Theses and Dissertations

Sediment samples taken from a washover deposit were used to determine the mode of sediment transport within overwash surges. The determination of sediment transport mode is based on the concept of hydraulic equivalency of different density grains. Hydraulic equivalency may be based on settling velocities or entrainment velocities. Two individual mineral grains of different densities cannot have the same settling and entrainment velocities. If the settling velocities of each grain are similar, then the less dense grain must be physically larger to settle at the same rate as the smaller denser mineral. However, once both of these grains have made …

A Method Of Modeling Multirate Two-Dimensional Recursive Digital Filters Author, Albert P. Gerheim

Electrical & Computer Engineering Theses & Dissertations

This dissertation presents a method of modeling two dimensional sampled data systems with two sampling rates in each dimension. This methodology is applied to the problem of synthesizing two dimensional velocity filters using one dimensional prototypes and multirate concepts.

The modeling method includes the replacement of scalar z-transforms of signals by vectors of polynomials, and the replacement of scalar z-transforms of impulse responses by matrices of polynomials.

The synthesis of velocity filters is accomplished through the use of coordinate transformations in the z-transform domain which skew the ω₁ -ω₂ axes on the unit bidisc. The filters synthesized using …

Continental Shelf Processes Affecting The Oceanography Of The South Atlantic Bight. Progress Report, 1 June 1980-1 June 1981, Larry P. Atkinson

CCPO Publications

(Introduction) In the past year we executed our largest field effort to date, GABEX-1. The vast amount of data gathered has now been reduced to workable form and we report on some of the first results in this report. The GABEX-1 measurements combined with other observations in the last year have greatly increased our understanding of the South Atlantic Bight during the spring transition period when the shelf goes from horizontal to vertical stratification.

This progress report contains selected reprints, drafts, and parts of technical reports that represent our work over the past three years.

Recommendations For Master's Level Programs In Computer Science: A Report Of The Acm Curriculum Committee On Computer Science, Kenneth I. Magel, Richard H. Austing, Alfs Berztiss, Gerald L. Engel, John W. Hamblen, A. A. J. Hoffmann, Robert Mathis

Computer Science Faculty Publications

The ACM Committee on Curriculum in Computer Science has spent two years investigating master's degree programs in Computer Science. This report contains the conclusions of that effort. Recommendations are made concerning the form, entrance requirements, possible courses, staffing levels, intent, library resources, and computing resources required for an academic, professional, or specialized master's degree. These recommendations specify minimum requirements which should be met by any master's programs. The Committee believes that the details of a particular master's program should be determined and continually updated by the faculty involved. A single or a small number of model programs are not as …

Role Of Gulf Stream Frontal Eddies In Forming Phytoplankton Patches On The Outer Southeastern Shelf, James A. Yoder, Larry P. Atkinson, Thomas N. Lee, Hongsuk H. Kim, Charles R. Mcclain

CCPO Publications

Continuous surface mapping of temperature, salinity, and chlorophyll along a 300-km segment of the Gulf Stream cyclonic front defined the spatial scales of a large diatom patch that persisted throughout a 10-day study. The patch was localized in the upwelled cold core of a Gulf Stream frontal eddy centered over the 200-m isobaths off Jacksonville, Florida, in April 1979. The µ g liter^-1 surface chlorophyll isopleth enclosed an area >1,000km² with an alongshore dimension of 130km. Surface chlorophyll exceeded 5µg liter^-1 within the upwelled cold core of the eddy, 10-100X higher than concentrations in Gulf Stream or …

Numerical Model Simulation Of Offshore Flow During The Winter Season, Maria Cintia Piccolo

OES Theses and Dissertations

Because of the step function variability of heat and moisture flux in coastal zones, adequate descriptive models of mesoscale coastal circulation and weather patterns demand high spatial resolution in the analysis of wind, temperature and moisture patterns. To obtain realistic concepts of offshore flow the sparse offshore data networks need to be supplemented by mesoscale numerical models. The problems associated with the modeling of offshore flow across the east coast of the United States during the winter season have been investigated with a simple two dimensional numerical model of the planetary boundary layer.

The model has two predictive equations for …

Geomorphology And Dynamics Of A Sand Wave In Lower Chesapeake Bay, Virginia, Gerardo Miguel Eduardo Perillo

OES Theses and Dissertations

A single, more or less isolated, sand wave in a sand wave field recently discovered in the lower Chesapeake Bay, Virginia, was studied intensively for morphology, sedimentology and in terms of dynamic processes. The morphologic investigation consisted of bathymetric surveys of the sand wave field and the specific sand wave. Twenty-five grab samples and four box cores were obtained from different segments of the feature studied. Textural parameters of the samples were determined, and a multivariate technique was utilized to identify subenvironments on the feature. The box cores provided information on the internal structure of the sand wave.

Observations of …

Sound Absorption In N2-H2O Gas Mixtures At Elevated Temperatures, Roger W. Meredith

Physics Theses & Dissertations

Sound absorption measurements were conducted in N₂ -H₂O gas mixtures at 297, 343, and 387 Kelvin to determine the location of the vibrational relaxation peak of nitrogen on the frequency/pressure, (f/P), axis as a function of humidity and temperature. At low humidities the best fit of the data is to a linear relationship between (f/P)_max and humidity (h) yields a slope of 1 .84 X 10⁴ Hz/ atm mole fraction at all three temperatures. The slope is the same as that reported by Zuckerwar and Griffin (2.00 X 10⁴ Hz/atm mole fraction) but is …

High Resolution Laser Absorption Spectroscopy Of Ozone Near 1129.4 Cm-1, Lawrence N. Majorana

Physics Theses & Dissertations

A Beer's Law experiment was performed with a tunable laser to determine self broadened line shape parameters of one infrared absorption ozone line in the v1 band for ten pressures from 0.26 to 6.29 Torr at 285K. SO₂ line positions were used for wavelength calibration. Line shapes were iteratively fitted to the Voigt function at a Doppler width of 29.54 MHz (HWHM) resulting in values for the integrated line• strength, ( S), of (0.144 +/- 0.007 ) x ·10^-20 cm-1/molecule cm-2, line center frequency, (υ_ο) of 1129.426 cm-1 and the Lorentzian contributions to half width, (α …

Hydrographic Observations In The Georgia Bight (April 1979), S. R. Lansey, L. P. Atkinson

CCPO Publications

During a cruise in the Georgia Bight in April 1979, an onshore-offshore hydrographic section of thirteen stations was repeated thirteen times. Four additional onshore-offshore hydrographic sections were completed north and south of the main section. Temperature, salinity, dissolved oxygen, and nutrient (N0₃, PO₄, and Si0₂) data were collected.

Two spin off eddies were observed at the Gulf Stream front at the shelfbreak. These eddies resulted in the upwelling of nutrient-enriched North Atlantic Central Water. A period of downwelling was observed between the two upwelling events. The cycling between upwelling and downwelling was relatively rapid. …

The Distribution Of Cesium-137, Copper, Lead And Zinc In Various Sedimentary Environments Of The James River Estuary, Virginia, Colin Stevenson Moy

OES Theses and Dissertations

Ten grab samples and eight cores were obtained within a short stretch of the James River estuary. The distribution of CU, Pb, Zn, Cs-137, organic carbon (TOC) and fine-grained sediments in various depositional environments were examined. Within the past quarter of a century, these measured parameters have been accumulating preferentially in the low energy environment (Burwell Bay). The inventory of Cs-137 in the cores was linearly related to the inventory of heavy metals and TOC. The concentrations of Cs-137 in the surface sediments vary linearly to those of the other parameters suggesting that Cs-137 may be used as a tracer …

Litter Production And Nutrient Content Of Litter In The Seasonally Flooded Dismal Swamp, Marta M. Gomez

Biological Sciences Theses & Dissertations

Litter production was studied in four plant communities in the Great Dismal Swamp, Virginia, that differ primarily in species composition and flooding regime. Greatest leaf deposition occurred in the more flooded communities, maple-gum (Acer-Nyssa) with 536 g m^-2 yr^-1 and cypress (Taxodium distichum (L.) Richard) with 528 g m^-2 yr^-1, followed by the cedar (Chamaecyparis thyoides (L.) BSP) and mixed hardwood (Quercus-Acer-Nyssa-Liquidambar) communities with 506 g m^-2 yr^-1 and 455 g m^-2 yr^-1, respectively. Litter nutrient concentrations were generally higher in the cypress and maple-gum stands, indicating greater nutrient availability …

Feasibility Of Quasi-Random Band Model In Evaluating Atmospheric Radiance, Navin Mirakhur

Mechanical & Aerospace Engineering Theses & Dissertations

The use of the quasi-random band model in evaluating the upwelling atmospheric radiation is investigated. The spectral transmittance and total band absorptance are evaluated for selected molecular bands by using the line-by-line model, quasi-random band model, exponential sum fit method, and empirical correlations, and these are compared with the available experimental results. The atmospheric transmittance and up­ welling radiance have been calculated by using the line-by-line and quasi-random models and are compared with the results of an existing program called LOWTRAN. The results obtained by the exponential sum fit and empirical relations are not in good agreement with experimental results …