Digital Commons Network^™

Analytical Modeling And Simulation For Investigation Of A Digital Gas Filter Correlation Radiometer, Catherine P. Mcgowan

Electrical & Computer Engineering Theses & Dissertations

This thesis investigates a digital gas filter correlation radiometer called the Tropospheric Radiometer for Atmospheric Chemistry and Environmental Research (TRACER), which will be used to remotely measure carbon monoxide at three levels in the troposphere. The nadir-viewing radiometer measures the differential absorption of radiation through the atmosphere at 4.67@m and 2.33pm wavelengths. This thesis develops an analytical model of the TRACER measurement process to evaluate the effect of varying certain system parameters on the measurement. The independent sampling criterion and the response of linear systems to random signals are explained. A parametric simulation model is also developed to evaluate the …

Investigation Of Effects Of Nose Bluntness And Angle Of Attack On Slender Bodies In Viscous Hypersonic Flows, Ashwini Kumar Sehgal

Mechanical & Aerospace Engineering Theses & Dissertations

Hypersonic flows over cones and straight biconic configurations are calculated for a wide range of free stream conditions in which the gas behind the shock is treated as perfect. Effect of angle of attack and nose bluntness on these slender bodies in air is investigated extensively. The numerical procedures are based on the solution of complete Navier-Stokes equations at the nose section and parabolized Navier Stokes equations further downstream. The flow field variables and surface quantities show significant differences when the angle of attack and nose bluntness are varied. The complete flow field is thoroughly analyzed with respect to velocity, …

Maximum Likelihood Estimation For Distributed Parameter Models Of Large Beam-Like Structures, Ji Yao Shen

Mechanical & Aerospace Engineering Theses & Dissertations

Proposed large space structures have many characteristics that give an advantage to modeling their structural dynamics by a set of partial differential equations (PDE's). By far, the most effort put forth in studying system identification and control to date has been based on finite element models. Despite its acceptability, such lumped parameter models have inevitable deficiencies primarily because of their complexity. Both approaches are complementary and each should be used where it is most effective. But the fact is that the distributed parameter approach has not been developed to the level of maturity as for the lumped parameter approach.

Motivated …

Magnetic-Field Distributions In Zinc-Nickel Ferrite, T. A. Dooling, Desmond C. Cook

Physics Faculty Publications

The Mössbauer effect has been used to study the microscopic magnetic properties of the cubic microwave ferrite (Zn_0.41Ni_0.59)Fe₂O₄ at 300 K. The magnetically split spectrum is broad and unresolved due to the overlap of the hyperfine magnetic fields at the tetrahedral and octahedral sites. This is caused by a distribution of magnetic fields at each site. The distribution is especially large and asymmetric at the octahedral site and is due to the fact that the iron atoms at this site are influenced by the presence of both iron and zinc at the tetrahedral …

An Erasable Optical Memory Based On Stimulated Electronic Transition Concept, James D. Satira

Electrical & Computer Engineering Theses & Dissertations

Erasable optical memory systems with a high storage density and a large data transfer rate are required for many real time data acquisition systems such as those placed aboard NASA's space born platforms. A new concept for erasable optical memory involving stimulated electronic transitions (SET) will meet these requirements. The SET concept useful in erasable optical storage systems was demonstrated in MgS and SrS doped with Eu and Sm. The optical properties of these materials were studied. The reading and writing wavelengths for these samples were determined to be 950 and 514 nm respectively. The peaks of the emission spectra …

Signal Processing Methodologies For An Acoustic Fetal Heart Rate Monitor, Robert A. Pretlow Iii

Electrical & Computer Engineering Theses & Dissertations

Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones within a noise-contaminated signal from a passive acoustic sensor. A linear predictor algorithm is utilized for detection of the heart tone event and additional processing derives heart rate. The linear predictor is adaptively "trained" in a least mean square error sense on generic fetal heart tones recorded from patients. A real time monitor system is described which outputs to a strip chart recorder for plotting the time history of the fetal heart rate. The system is validated in the context of the …

Prediction And Control Of Asymmetric Vortical Flows Around Slender Bodies Using Navier-Stokes Equations, Tin-Chee Wong

Mechanical & Aerospace Engineering Theses & Dissertations

Steady and unsteady vortex-dominated flows around slender bodies at high angles of attack are solved using the unsteady, compressible Navier-Stokes equations. An implicit upwind, finite-volume scheme is used for the numerical computations.

For supersonic flows past pointed bodies, the locally-conical flow assumption has been used. Asymmetric flows past five-degree semiapex cones using the thin-layer Navier-Stokes equations at different angles of attack, freestream Mach numbers, Reynolds numbers, grid fineness, computational domain size, sources of disturbances and cross-section shapes have been studied. The onset of flow asymmetry occurs when the relative incidence of pointed forebodies exceeds certain critical values. At these critical …

Rx For Success At Back Bay National Wildlife Refuge: Take Two Committed Partners-Add Water, Janet Taylor, Julia Herrick, Ben Mathias

V. Poster Abstracts

As part of a major effort to improve habitats for waterfowl and other wetland-dependent wildlife, Ducks Unlimited, Inc. is contributing $187,500 in matching funds to help the U.S. Fish and Wildlife Service rehabilitate wetland impoundments at Back Bay NWR.

The three-year project will increase Refuge management capabilities on existing wetland areas, create 300 acres of new marsh habitat and increase water management flexibility throughout the impoundment system. Components of the project include:

• Raising and re-sloping 8 miles of existing dikes
• Installing 13 new water control structures
• Constructing 6,000 feet of new dikes
• Creating two storage pools totalling 53 acres and …

Environmental Education: A Chance For The Future, Ben Mathias

V. Poster Abstracts

The U.S. Fish and Wildlife Service is committed to providing environmental education opportunities for the Nation's student body. Local, regional and national educators are invited to investigate and utilize the resources of Back Bay National Wildlife Refuge with their colleagues and students. Teacher workshops at the Refuge provide orientation to Refuge lands, outdoor classroom sites, trails, interpretive facilities and equipment, and potential field activities. Refuge staff members are available to assist with: • Preliminary planning • Group scheduling • Library research • Workshop registration • Trip logistics and • On-site group orientation. Most classroom sites, associated trails/boardwalks, and Visitor Contact …

Assessment Of Organic And Metal Contaminants In Lower Back Bay And Upper Currituck Sound, Kate Benkert

V. Poster Abstracts

Studies were conducted at Mackay Island National Wildlife Refuge in 1988 and 1989 to provide baseline data for an assessment of organic chemicals and metal contaminants in the aquatic ecosystem. Longnose gar, gizzard shad, snapping turtles, common rangia clams and sediments were collected from sites in lower Back Bay and upper Currituck Sound for contaminant analyses.

Composite sediment samples were analyzed for the presence of metals, organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs). Organochlorine pesticides were not detected in the sediments. Various PAH compounds were detected in the sediments, although at trace concentrations which just exceeded the analytical detection limit …

Refuge Land Acquisition: Helping Preserve Back Bay's Wildlife Heritage, Julia Herrick, Ben Mathias, Janet Taylor

V. Poster Abstracts

The once-renowned waterfowl populations and bass fishery of Back Bay, Virginia have declined dramatically in recent years. Lands surrounding Back Bay are increasingly threatened by on-going and potential land development. These lands serve as an important filter for pollutant and sediment-laden runoff from adjacent areas. The boundary of the Back Bay National Wildlife Refuge was expanded in 1989 to include an additional 6,340 acres of brackish marsh, forested swamp, and "critical edge" upland habitat, important to a variety of wildlife species and for its natural filtering effect. Within the U.S. Fish and Wildlife Service's policy of working with willing sellers, …

Best Lp Aapproximation With Multiple Constraints For 1 ⩽ P < ∞, J. J. Swetits, S. E. Weinstein, Yuesheng Xu

Mathematics & Statistics Faculty Publications

The problem considered in this paper is best L_p approximation with multiple constraints for 1 ⩽ p < ∞. Characterizations of best L_p approximations from multiple n-convex splines and functions are established and the relationship between them is investigated. Applications to best monotone convex approximation are studied.

A Duality Approach To Best Uniform Convex Approximation, S. E. Weinstein, Yuesheng Xu

Mathematics & Statistics Faculty Publications

Let C[a, b] be the space of continuous functions on [a, b] endowed with the uniform norm llƒll _∞ = sup{ Iƒ(x)1 :x∈ [a, b]}. Let K be the set of convex functions defined on [a, b]. A function g* ∈ K is said to be a best uniform convex approximation to ƒ ∈ C[a, b] if ∥ƒ - g*∥ _∞ = inf { ∥ƒ - g∥_∞ : g ∈ K}.

Parametric Instability Of Supersonic Shear Layers Induced By Periodic Mach Waves, Fang Q. Hu, Christopher K. W. Tam

Mathematics & Statistics Faculty Publications

It is suggested that parametric instability can be induced in a confined supersonic shear layer by the use of a periodic Mach wave system generated by a wavy wall. The existence of such an instability solution is demonstrated computationally by solving the Floquet system of equations. The solution is constructed by means of a Fourier-Chebyshev expansion. Numerical convergence is assured by using a very large number of Fourier and Chebyshev basis functions. The computed growth rate of the induced flow instability is found to vary linearly with the amplitude of the mach waves when the amplitude is not excessively large. …

Electric Field Induced Emission As A Diagnostic Tool For Measurement Of Local Electric Field Strengths, A. N. Dharamsi, K. H. Schoenbach

Bioelectrics Publications

The phenomenon of electric field induced (EFI) emission is examined in several diatomic and polyatomic molecules. The possibility of using this phenomenon as a diagnostic tool to measure, nonintrusively, the strength and direction of local electric fields in plasmas is discussed. An estimate of the EFI signal emitted in a typical application plasma is given. This yields a lower bound on the detector sensitivity necessary to exploit EFI emission in practical applications. It is concluded that, at present, the EFI signal could be measured by some very sensitive infrared detection schemes available. Current progress in infrared detector technology, if maintained, …

Observations Of The Phytoplankton Standing Crop At The Shelf Margin Of The Mid Atlantic Bight, Bruce B. Wagoner, Harold G. Marshall

Biological Sciences Faculty Publications

A comparison of the total percentage cell abundance and cell biovolume relationships of major phytoplankton categories was made between two station sets across the shelf margin. Diatom values for abundance and biovolume were greater at oceanic stations compared to the outer shelf stations, with dinoflagellates having the reverse pattern. The composite contributions to biovolume and abundance in the standing crop from other phytoplankton categories were greater over the outer shelf than beyond the shelf margin. The major source of biovolume (biomass) from the outer shelf and these oceanic stations came from the diatoms and dinoflagellates, with an average mean of …

Second Coefficient Of Viscosity In Air, Robert L. Ash, Allan J. Zuckerwar, Zhonquan Zheng

Mechanical & Aerospace Engineering Faculty Publications

Acoustic attenuation measurements in air were analyzed in order to estimate the second coefficient of viscosity. Data over a temperature range of 11 C to 50 C and at relative humidities between 6 percent and 91 percent were used. This analysis showed that the second coefficient of viscosity varied between 1900 and 20,000 times larger than the dynamic or first coefficient of viscosity over the temperature and humidity range of the data. In addition, the data showed that the molecular relaxation effects, which are responsible for the magnitude of the second coefficient of viscosity, place severe limits on the use …

Distribution Of Terrestrially Derived Dissolved Organic Matter On The Southeastern United States Continental Shelf, Mary Ann Moran, Lawrence R. Pomeroy, Edward S. Sheppard, Larry P. Atkinson, Robert E. Hodson

CCPO Publications

Dissolved lignin-derived compounds in seawater indicate the presence of organic matter originating from vascular plants and therefore from terrestrial (upland and coastal marsh) ecosystems. We used a hydrophobic resin to concentrate lignin-rich humic substances and to determine concentrations of lignin oxidation products (vanillyl lignin phenols) for waters of the continental shelf of the southeastern U.S. Lignin phenol concentrations ranged from 0.05 to 4.2µg liter‒1 and accounted for 0.002–0.13% of the total dissolved organic carbon (DOC) pool in continental shelf waters. Dissolved lignin concentrations were generally highest near the shore and in those areas receiving greatest river and marsh …

Gulf Stream Frontal Eddy Influence On Productivity Of The Southeast United States Continental Shelf, Thomas N. Lee, James A. Yoder, Larry P. Atkinson

CCPO Publications

Weekly period meanders and eddies are persistent features of Gulf Stream frontal dynamics from Miami, Florida, to Cape Hatteras, North Carolina. Satellite imagery and moored current and temperature records reveal a spatial pattern of preferred regions for growth and decay of frontal disturbances. Growth regions occur off Miami, Cape Canaveral, and Cape Fear due to baroclinic instability, and decay occurs in the confines of the Straits of Florida between Miami and Palm Beach, between 30° and 32°N where the stream approaches the topographic feature known as the Charleston bump and between 33°N and Cape Hatteras. Eddy decay regions are associated …

A Study To Determine The Supply And Demand Of Marketing Education Teachers Within The Next Five School Years In The Tidewater, Virginia Area, Christin Leigh Gilbert

OTS Master's Level Projects & Papers

The following goals were established to find a solution to this problem: 1. Determine the number of graduates in this field that will be seeking employment; 2. Determine the number of positions to be filled due to the number of persons retiring from Marketing Education teaching positions; 3. Determine the number of positions to be filled due to career changes of Marketing Education teachers; 4. Determine the growth of local school district Marketing Education programs; 5. Determine the future needs for Marketing Education teachers.

The Implementation Of "Lab 2000" And "Synergistic Systems" In Middle School Laboratories In Virginia, Patricia M. Ways

OTS Master's Level Projects & Papers

To solve this problem, the following goals were developed: 1. Determine the effectiveness of the "high tech" laboratories with regard to implementing the middle school curriculum; 2. Make recommendations for facility and curriculum changes based upon the observations of the practicing middle school teachers.

A Study To Determine The Effectiveness Of Self-Paced Learning Activity Packaged Compared With Various Teacher Directed Instructional Classroom Techniques On Fundamentals Of Marketing Students At Lakeland High School, Edward L. Sawyer

OTS Master's Level Projects & Papers

The hypothesis of this study was: 1) there would be no significant difference in the learning outcomes of the students who were exposed to various teaching techniques and those who were exposed to only using IDECC learning activity packages.

The Ability Of The Special Needs Child In Comparison To The Average Child In A Beginning Computerized Keyboarding Class, Deborah K. Marshall

OTS Master's Level Projects & Papers

The problem of this study was to determine how the ability of the special needs child, when mainstreamed into a Beginning Computerized Keyboarding course, compared to that of the average child. The hypothesis was that there was no significant difference in the learning of special needs students and academically average students when taught Beginning Computerized Keyboarding.

A Survey Of The Student Attitudes Toward Woodworking Technology At F. E. Kellam High School, Michael R. Vanture

OTS Master's Level Projects & Papers

The problems of this study was to determine the reason or reasons behind the selection of woods technology by those students who were fulfilling an elective course credit at Kellam High School. Among those ideas that were being examined were 1) the student's attraction to the material and the product that results from the material; 2) other influences such as parents, peers, and school counselors; 3) to what degree does occupational or vocational intent interest the student.

Nonlinear-Interaction Of A Detonation Vorticity Wave, D. G. Lasseigne, T. L. Jackson, M. Y. Hussaini

Mathematics & Statistics Faculty Publications

The interaction of an oblique, overdriven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multidomain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results whenever obtained in this study agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient …

Self-Activation And Inhibition: A Simple Nonlinear Model, J. A. Adam

Mathematics & Statistics Faculty Publications

Self-activation and self-inhibition of cell number density (or growth factor concentration) due to a spatially localized source are studied. Both the time-independent and time-dependent models are examined, and the linear stability of the resulting three steady states of the former is discussed.

Activator-Inhibitor Control Of Tissue Growth, John A. Adam

Mathematics & Statistics Faculty Publications

This note develops a simple model for the competition between activator and inhibitor control mechanisms in one-dimensional tissue growth. The pedagogic usefulness of such a model is that it is easily accessible to undergraduate applied mathematicians and is suggestive of behavior known to occur in more realistic biological systems (e.g., some types of cancer). The limitations of the model are obvious and can provide a basis for discussion of the applicability of complementary levels of description in mathematical modeling.

Virginia Woolf's Keen Sensitivity To War: It's Roots And It's Impact On Her Novels, Nancy Topping Bazin, Jane Hamovit Lauter

English Faculty Publications

(First paragraph) War InspIred Horror In Virginia Woolf. Her antipathy toward those who cause wars is evident in her two essays, A Room of One's Own and Three Guineas. The impact of war on her fiction expands from a portrayal of individuals as victims of war to a vision of war that encompasses the possible annihilation of civilization. Between the Acts, Woolf's final novel, is obviously an artistic response to the threat posed by World War II. However, a close examination of her works reveals, to a surprising degree, her early and persistent preoccupation with the consequences of war, …

Observations Of A Cyclonic Ring: Gulf Stream Coalescence Event Over The Blake Plateau, Julie Mcclean-Padman, Larry P. Atkinson

CCPO Publications

Hydrographic data collected in September 1980 over the Blake Plateau were analyzed using a combination of empirical search and inverse techniques. Five sections, extending from the continental shelf break eastward across the Blake Plateau, were positioned at approximately 1-degrees intervals between 28-degrees and 32-degrees-N. The empirical search procedure was applied to four closed regions (boxes), constructed from adjacent sections, where each region was assumed to consist of two conservative layers. Five geostrophic velocity sections were obtained using the average optimum reference level for the four boxes. The inverse technique provided barotropic correction velocities that caused all layers to conserve mass. …

The Effect Of Age Misreporting In China On The Calculation Of Mortality Rates At Very High Ages, Ansley J. Coale, Shaomin Li

Management Faculty Publications

When mortality rates by age are calculated from recorded deaths and enumerated populations, rates at higher ages are typically in error because of misstated ages. Mortality rates for China in 1981 have been calculated from the number of deaths in 1981 in each household recorded in the 1982 census, and from the census population back-projected one year. Because age was determined from date of birth, and because persons of the Chinese culture have very precise knowledge of date of birth, the mortality rates even at high ages should be unusually accurate. This expectation is fulfilled for most of China, but …