Digital Commons Network^™

Block Transform Coding Of Presample Filtered Data, Thomas A. Shull

Electrical & Computer Engineering Theses & Dissertations

This dissertation addresses the application of non-adaptive transform coding for bit rate reduction of presampled filtered data. Transform coding is examined as an alternative to conventional pulse code modulation (PCM) for multi-source, fixed rate data acquisition systems. Typical bandlimiting presample filters introduce redundancy into the sequence of data samples. Linear transformation of successive N-length blocks of the data sequence and subsequent binary coding of the resulting components is shown to lead to reduced average bit rate for the same less distortion as PCM.

Four Butterworth filters, two corresponding to eight bit PCM systems, and two corresponding to ten bit PCM …

Changes In The Lower Chesapeake Bay Food-Chain In Presence Of The Sea Nettle Chrysaora-Quinquecirrha (Scyphomedusa), David Feigenbaum, Michael Kelly

OES Faculty Publications

The abundance of 4 levels of the lower Chesapeake Bay food chain (Chlorophyll a, herbivores, ctenophore Mnemiopsis leidyi, and Scyphomedusa Chrysaora quinquecirrha) were moni­tored twice weekly at 4 stations from May 10 through Sep 30, 1982 in the Lafayette and Elizabeth Rivers (Virginia). The herbivore standing stock, largely copepods, declined sharply in late May when M. Jeidyi appeared, but rebounded a month later when C. quinquecirrha medusae reduced the ctenophore population. Despite the additional presence of Aurelia aurita (Scyphomedusa) from Jul onward, herbivore abundance remained at moderate levels until the end of the study period. Phytoplankton abundance fluctuated …

Staff Nurses' Self-Esteem As It Relates To Working In Specialty Areas, Donna Lynn Evans

Ellmer School of Nursing Theses & Dissertations

This study compared the levels of self-esteem of hospital staff nurses working in specialty areas versus those working in general medical-surgical areas. Fifty registered nurses employed full-time in staff positions at a large, acute-care hospital participated in the study. After indicating the area of the hospital in which they worked, the type of education they had, and the number of years of experience as a registered nurse, they then completed the Tennessee Self-Concept Scale. Scores were then compared using independent t-tests applied to the area in which the subject worked, the type of education, and the years of experience. Results …

Underwater Acoustic Wavefront Phase Fluctuations, George L. Vojtech Jr.

OES Theses and Dissertations

In conventional underwater acoustics sound propagation is generally modeled and applied as a coherent or incoherent process. This paper addresses a relatively new theory, that of a range driven increasingly incoherent ray propagation through a real ocean environment, Possible mechanisms are discussed and experimental data presented to reinforce the theory.

Breeding Birds In Cedar Stands In The Great Dismal Swamp, Karen A. Terwilliger, Robert K. Rose

Biological Sciences Faculty Publications

The Great Dismal Swamp located in the coastal plain on the Virginia- North Carolina border, has long been recognized as a vegetationally distinctive region with many unusual geological and biological features. Formerly at least twice the currently estimated size of 85,000 hectares (Carter 1979), the Great Dismal Swamp is still shrinking because of a dropping water table caused by more than 200 years of logging, ditching, and other human activities. In 1973, the Union Camp Corporation donated a 19,871-hectare tract located near Suffolk, Virginia. to The Nature Conservancy, which transferred the land to the U.S. Fish and Wildlife Service. This …

A Study To Determine The Effectiveness Of The Vocational Resource Program In Newport News Public Schools, Newport News, Virginia, Maury Eugene Middleton

OTS Master's Level Projects & Papers

The objectives of this research were: 1. To determine to what extent the services were being used and if they were not, why; 2. To determine the usefulness of the services provided by the Vocational Resource Program; 3. To determine the desired needs of the teachers that were covered by the Vocational Resource Program; 4. To determine the effectiveness of the vocational aides.

Assessment Criteria For Special Education Students In Vocational Education, Joyce A. Francis

OTS Master's Level Projects & Papers

The basic research questions of this study are as follows: 1. What are the exit competencies for a given learning disabled according to the student's career/vocational goals and/or needs? 2. Is it possible for a special education student to be placed in a vocational learning environment with their peers that are "normal" (mainstreaming)? 3. Can a special education student be productive during this period of mainstreaming?

Review Of Upwelling Off The Southeastern United States And Its Effect On Continental-Shelf Nutrient Concentrations And Primary Productivity, Larry P. Atkinson, James A. Yonder, Thomas N. Lee

CCPO Publications

Gulf Stream induced upwelling occurs along the length of the southeastern United States continental shelf break. Upwelling events are produced by northward propagating Gulf Streams frontal meanders and eddies and travel northwards with these features. Meanders and eddies occur throughout the year in a period band of 2-14 days; however, resultant upwellings can affect the shelf quite differently. During fall, winter, and spring, upwelling is restricted to the outer shelf by cross-shelf density distributions, but in the summer upwelled water may penetrate across as a subsurface intrusion if aided by upwelling-favorable winds. If water does penetrate across the shelf, it …

Coastal Upwelling Off The Rias Bajas, Galicia, Northwest Spain I: Hydrographic Studies, J. O. Blanton, L. P. Atkinson, F. Fernandez De Castillejo, A. Lavin Montero

CCPO Publications

Coastal upwelling occurs off the Rias Bajas of Spain between April and October. Superimposed on large-scale upwelling is a mesoscale regime of enhanced upwelling induced by topographic influences. We show that the region surrounding Cape Finisterre has intensified topographically induced upwelling.

The rias have a relatively unobstructed connection with the open ocean. Upwelling of high nitrate water on the continental shelf by Ekman transport sets up pressure gradients at the mouth of the rias that induce upwelled water to flow into the rias. Deep water in the rias responds directly to cycles of upwelling and downwelling on the continental shelf.

Trace-Elements In Ilmenite - A Way To Discriminate Provenance Or Age In Coastal Sands, Dennis A. Darby

OES Faculty Publications

Trace elements and Ti percentage in ilmenite grains magnetically separated from modern and late Pleistocene coastal sands of southeastern Virginia and northwestern North Carolina were used to distinguish different deposits. Multivariate analysis of ilmenite composition (Ti, Mn, Mg, Cr, V, Ni, and Cu) from coastal deposits and potential source rivers enabled the identification of dominant source rivers. Using the trace element content of one mineral instead of heavy-mineral suites eliminated most of the hydraulic sorting, selective weathering, and intrastratal solution problems that often obscure heavy-mineral provenance determinations. Most ilmenite grains lacked exsolution or twinning, which are common to ilmenite; however, …

Mass Spectrometric Studies Of Oxygen Isotope Exchange Reactions With Oxide Surfaces, Gayle J. Allen

Chemistry & Biochemistry Theses & Dissertations

Isotopic exchange reactions with the surface of amorphous silica and crystalline quartz were studied mass spectrometrically. A mixture of approximately 2%18_o2 in neon was used as the test gas, and was passed over the surface of the oxides. Measurements were taken as a function of temperature and residence time, for kinetic studies.

These studies clearly show a second order rate law for the surfaces examined. The rate constant on amorphous silica was 2.2xl0²L/mol/sec. The energy of activation was 35.3 kcal/mol and the frequency factor was l.35xl0⁹L/mol/sec. On the crystalline quartz the rate constant was 2.0xl0 …

A Study Of The Attitudes And Beliefs Of Tidewater Area Businesses Regarding The Employment Of The Trainable Mentally Retarded, Fred Hadley

OTS Master's Level Projects & Papers

The research goals of this study were: 1. Accumulate and analyze data on the attitudes currently held by both prospective and actual employers regarding the employment of mentally retarded persons; 2. Demonstrate a relationship between the attitudes of employers who had actually hired mentally retarded persons and those who had not.

Determining The Validity Of The Auto Mechanics I Curriculum And Student Competencies At Virginia Peninsula Vo-Tech (South Campus), Bruce M. Godwin

OTS Master's Level Projects & Papers

The objectives of this study were as follows: 1. Craft committees, consisting of members of the business community, were used to review the curriculum and offer ideas that would help update the curriculum; 2. An employer follow-up was developed to survey the abilities of automotive graduates working in the community and determine the effectiveness of their educational experience at Vo-Tech; 3. By talking to area employees and industry representatives, we were able to determine those work traits most necessary for successful employment.

An Analysis Of The Reasons And Influences Causing Students To Enroll In Industrial Arts Education Programs At Virginia Universities, Robert Beauter

OTS Master's Level Projects & Papers

The problem of this study was to conduct a survey of industrial arts education majors at Virginia universities to identify and analyze their reasons for enrolling in a university industrial arts education program and who had the most influence on their decision. This data would be used as an aid in recruiting students for the Industrial Arts Education Program at Old Dominion University.

Systematic Estimate Of Binding Energies Of Weakly Bound Diatomic Molecules, Linda L. Vahala, Mark D. Havey

Electrical & Computer Engineering Faculty Publications

There is often insufficient spectroscopic data for a full RKR inversion to yield a potential for weakly bound diatomic molecules. In these cases, parametrized functions such as the Morse or Thakkar potentials may be used to obtain estimates of the binding energy. The Thakkar potential is more flexible, and has been used successfully on some weakly bound systems. In the more usual case, the Thakkar parameter p, which determines long range behavior R^-p, is chosen by p=-a₁-1, where a₁ is the first Dunham coefficient; p is usually noninteger. The authors present …

The Marine Biogeochemistry Of Selenium: A Re-Evaluation, Gregory A. Cutter, Kenneth W. Bruland

OES Faculty Publications

Vertical and horizontal profiles from the North and South Pacific Oceans demonstrate the existence of three species of dissolved selenium: selenite, selenate, and organic selenide (operationally defined). In surface waters, organic selenide makes up about 80% of the total dissolved selenium, selenite concentrations are uniformly low, and selenate concentrations rise with increased vertical mixing. The organic selenide maximum (thought to consist of seleno-amino acids in peptides) coincides with the maxima of primary productivity, pigments, bioluminescence, and dissolved free amino acids. Deep ocean waters are enriched in selenite and selenate, while organic selenide is nondetectable. In suboxic waters of the tropical …

Episodic Nutrient Supply To A Kelp Forest Ecosystem In Southern California, Richard C. Zimmerman, James N. Kremer

OES Faculty Publications

Temporal patterns of nutrient input into a Southern California kelp forest were measured using traditional hydrocast sampling coupled with high frequency temperature profiling. Patterns of nutrient input were related to growth rates of Macrocystis pyrifera located in an adjacent kelp forest. There were 2 distinct components to the pattern of nutrient availability. The long term, or seasonal, component was consistent with large-scale storm-induced mixing and horizontal advection during winter months. In addition, vertical motions of the thermocline, bringing nutrients into the kelp forest, occurred throughout the year with a frequency of about 2 per day and were strongest during the …

Radiation Damage To Gaas Solar Cells Including Isotropic Effects, Larry Victor Stock

Physics Theses & Dissertations

A model is developed for the short circuit current of a GaAs solar cell due to radiation (proton or electron) induced defects in the crystal structure. This model is verified by a comparison with proton and electron irradiation results. For electron radiation and energetic protons (energy> 10 MeV), it is found that the damage in the crystal is independent of the angle of incidence. On the other hand, for lower energy proton radiation, the damage as a function of cell thickness is highly dependent on incident angle and energy. The cell's response to low energy protons is strongly dependent on …

Valuing In The Arts, Nonna B. Runner

Institute for the Humanities Theses

The topic of this thesis, valuing in the arts, involves the fine and performing arts, cultural values, kinds of education, and the quality of life. The purpose in talking about the value of the arts is to show how and why they have been valued throughout recorded history, to present an approach to art which fosters personal growth and enjoyment in the interaction with the arts, and to present arguments for the continued support by the present society for their encouragement and preservation. I will discuss false impressions about art which have limited the general public's enjoyment of arts, then …

Collision-Induced Bands Of Lithium-Rare Gas Molecules, Wen Jong Wang

Physics Theses & Dissertations

Lithium vapor is optically excited by two-step laser excitation of the 3d state in the presence of the rare gases He, Ne, Ar, Kr, and Xe. Collision induced bands are observed in Li-Ar, Li-Kr, and Li-Xe mixtures. The bands are believed to be due to transitions to the dissociating 2s~ ground state from states above the 2p state of the Li-RG molecules. The Li-Ar, Li-Kr, and Li-Xe 3sб -2sб collision induced bands are progressively shifted, for the heavier rare gases, further to the red of the asymptotic atomic Li 3s-2s energy difference. A qualitative comparison is made between the spectra …

The Effect Of Polynuclear Aromatic Hydrocarbons On The Fecundity Of Acartia Tonsa (Calanoid Copepoda), Juanita Y. Grabarczyk

OES Theses and Dissertations

The concentrations of polynuclear aromatic hydrocarbons (PNAHs) were determined for several stations in the Elizabeth River. Thirteen PNAHs of the sixteen EPA priority pollutant PNAHs were present in the particulate fraction. The concentrations ranged from 10.0 ng/1 to 1000 ng/1. Ten of the sixteen EPA priority pollutant PNAH were present in the dissolved phase. Concentrations ranged from 2.0 ng/1 to 100 ng/1.

The environmental PNAHs concentrations were used to determine test concentrations. Bioassays were conducted to determine the effects of indigenous concentrations of seven predominant PNAHs (0.01 mg/1 to 2.4 mg/1 concentrations) on the fecundity of Acartia tonsa (calanoid Copepoda). …

Close-Coupling Calculations For Naar, Nane, And Nahe, Linda Lindroth Vahala

Physics Theses & Dissertations

The non-adiabatic close-coupled theory, developed by Mies and by George, is employed in a time-independent molecular calculation for Na-rare gas collisions in a radiations field. The intensity of the Na D1/D2 lines is calculated for both blue- and red-wing excitation and is in good agreement with the experimental results of Havey, Copeland, and Wang for NaAr. The effects of different Born-Oppenheimer potentials on D1/D2 line intensity is considered by also treating NaNe and NaHe. The individual parity contributions to the line intensities are significantly different from each other.

Adaptations Of Dolphin Vision To The Oceanic Environment, Andre Rivamonte

OES Theses and Dissertations

The objective of this study has been to develop an hypothesis explaining comparable aerial and underwater visual acuity of the bottlenose dolphin, Tursiops truncatus. This objective was accomplished by integrating the findings of other dolphin researchers working in the fields of comparative psychology, histology and ophthalmology. Their combined results enabled the formulation of a schematic dolphin eye. It is proposed that a dolphin lens, similar to the spherical lens of teleost fish with a rigid core of uniformly high refractive index and a margin of radially decreasing refractive index, could function as a bifocal lens and compensate for the eye's …

The Effects Of Dominant Species Removal On Subtidal Community Development, H. Russell Barker Jr.

Biological Sciences Theses & Dissertations

Acrylic panels were used to follow the development of the fouling community at Channel Points, Lynnhaven Bay, Virginia, from April through October 1979. The roles of Membranipora tenuis, an encrusting ectoproct, and Molgula manhattensis, a solitary tunicate, were studied by removing each species from the developing community on a weekly basis.

Early colonization was dominated by Membranipora followed by Corophium spp. (Amphipoda), Polydora ligni (Polychaeta), and Balanus eberneus (Arthropoda). Molgula colonized the panels later in the study and became a dominant occupier of primary space by the end of the study.

The removal of Membranipora and Molgula …

Employee Perceptions Of Performance Appraisal Systems: Causal Determinants Of Fairness, Accuracy, And Acceptability, Michael Dale Secunda

Psychology Theses & Dissertations

The purpose of this research was to develop an initial model of employee perceptions of performance appraisal systems which would integrate available literature and provide a point of departure for future research endeavors. To accomplish these goals, this study had three objectives: (1) integrate the large body of literature to develop constructs that adequately describe employee perceptions of appraisal processes and systems, (2) integrate these constructs into a causal model that is consistent with current literature, and (3) test the model using linear structural modeling.

Seven constructs hypothesized as representing various aspects of employee perceptions were conceptualized and operationalized, and …

The Distribution Of Phytoplankton In Frontal Regions Of The Lower Chesapeake Bay, Richard V. Lacouture

OES Theses and Dissertations

The spatial and temporal distribution of phytoplankton was measured in relation to frontal areas located in the entrance to the Chesapeake Bay. Phytoplankton biomass, taxonomy, and several physical parameters were measured on fifteen sampling cruises between September,1981 and February, 1983.

Several statistical tests revealed that phytoplankton biomass did not accumulate at the fronts and that generally the distribution of phytoplankton biomass was homogenous across the frontal region. The cell count data indicated that the community structure of the phytoplankton assemblage was usually very similar on both sides of the front. The data which was concerned with temporal variations in the …

The Effects Of The Mud Snail Ilyanassa Obsoleta (Say) Upon The Benthic Community Of Broad Bay, Virginia, Wick Timothy Harlan

Biological Sciences Theses & Dissertations

The effects of the presence of the mud snail Ilyanassa obsoleta (Say) upon the benthic community of Broad Bay, Virginia were examined through artificial removal and exclusion of the snail and artificial increase of the snail population. The enclosure treatment exhibited a significantly higher number of macrofaunal individuals than the control. The control had a significantly higher number of meiofaunal individuals than either treatment. There were no significant differences for the chlorophyll a. The increase in macrofauna and corresponding decrease in meiofauna were probably due to cage effects and not snail densities. The presence of the fences can act as …

Circuit Analysis Of A Gas Flow Switch, Teri Marie Owens

Electrical & Computer Engineering Theses & Dissertations

The circuit analysis of a gas flow switch is presented. The objective of the analysis is to model the switching process during spark gap breakdown. This information is useful in understanding switch operation and identifying ways to improve switch performance.

A lumped circuit model is used to describe a gas flow switch during the switching process. Certain circuit element values are determined experimentally through static tests. Other component values, including a time-varying switch resistance and inductance, are estimated from current measurements. In particular, unknown constants in expressions for gap resistance and inductance are determined using an iterative parameter estimation technique. …

Experiments On Melting Around An Isothermal Horizontal Cylinder Under Computer Control, Timothy Moore Rothgeb

Mechanical & Aerospace Engineering Theses & Dissertations

The melting of a solid around an isothermal horizontal cylinder is a physical phenomenon which must be understood when attempting to design a latent heat storage system. The desire to design such a system is the motivating factor in this research. To gain this understanding of the fundamental melting processes several experiments were designed, and two sets of Stefan and Rayleigh number experiments were undertaken. Experiments were also performed to determine the properties of the paraffin that was used in these investigations. During the investigations of the melting processes, the temperature was measured at several locations throughout the liquid and …

Determination Of N,N'-Diphenylguanidine In Biological Tissues And Fluids Using High Pressure Liquid Chromatography, Edward Sidney Hunter Iii

Chemistry & Biochemistry Theses & Dissertations

N,N'-Diphenylguanidine (DPG) is a potentially toxic compound used in the vulcanization of rubber products. Distribution of DPG in hybrid mice (C57BL/6J interbred with DAB₂) was determined following intraperitoneal injection. Urine, fecal material, whole blood and tissues were collected at various times after administration of DPG and the extracts analyzed for DPG by high pressure liquid chromatography. Recovery of DPG from spiked urine and whole blood exceed 90%, however, the recovery of DPG from spiked tissue samples was approximately 70%.

DPG concentration in whole blood reached a maximum within ten minutes and rapidly decreased through 180 minutes after administration …