Digital Commons Network^™

A Geophysical Study Of The Easternmost Piedmont: Brunswick County, Virginia, Mark A. Corbin

OES Theses and Dissertations

Gravity and magnetic models indicate that a steeply dipping, mylonitic shear zone recognized by reconnaissance mapping in the easternmost Piedmont of Brunswick County, Virginia is a listric fault. A pronounced 3 to 5 mgal Bouguer anomaly high is associated with the fault zone. A band of N10° trending aeromagnetic anomalies delineate the areal extent of the fault zone. The fault zone flattens eastward over a short distance to a depth of 15 kms where it joins a near horizontal surface that cuts across the region. This surface is herein interpreted to be a decollement. The fault zone of this study …

Synthesis Of An Efficient Band Mechanism For Robots And Prosthetic Devices, Run Chen Zhou

Mechanical & Aerospace Engineering Theses & Dissertations

A noncircular pulley has been applied to improve the system efficiency of an electrical-powered elbow prosthesis. The dynamics of the motor and the prosthetic arm have been incorporated into the kinematic synthesis relationships for determining the pulley profile that maximizes the efficiency of the elbow prosthesis.

The nonlinear dynamic equations have been solved by the code Differential Equation (DE) while determining the motor power and efficiency which are the criteria in the nonlinear programming problem. The optimal design variables for determining the pulley profile along with some simulation results have been obtained from an optimization program (based on the Generalized …

Electrostatic Effects On Airborne Asbestos Monitoring, Roxanne Francis

Biological Sciences Theses & Dissertations

The affects of electrostatic forces on the Membrane Filter Method (MFM) used for air-borne asbestos monitoring have been investigated for many years. Several studies have indicated that these forces interfere with the collection of asbestos fibers on the membrane filter, which results in an underestimated analysis of the airborne concentration. By varying the electroconductivity of the extension cowls on the filter cassettes, it was speculated that the significance of the electrostatic forces could be statistically analyzed. Four sets of filter cassettes with grounded conductive (GC) extension cowls, ungrounded conductive (UC) extension cowls, grounded nonconductive (GN) extension cowls, and ungrounded nonconductive …

Lithofacies Of The Pliocene Yorktown Formation In The Vicinity Of Kingsmill On The James River, Virginia, Michael David Lawless

OES Theses and Dissertations

The Yorktown Formation beds which crop out along the James River in southeastern Virginia near Kingsmill and Carter's Grove are lithologically described in order to compare them with the "typical" Yorktown beds upriver in the area of Fort Boykins, Rushmere, and Cobham Wharf. Thirty-four stratigraphic sections are constructed of the bluffs along the river. The Yorktown beds in the area of Kingsmill and Cobham Wharf are divided into ten lithofacies: the silty sand facies (B), the Chesapecten facies (C), the Glycymeris facies (D), the Chama facies (E), the glauconitic biofragmental sand facies (F), the laminated silty clay facies (G), the …

Domain Decomposition For Multigrid, Finite Volume Flow Solvers, Victor Robert Lessard

Mechanical & Aerospace Engineering Theses & Dissertations

Computing the flow fields about three-dimensional complex configurations accurately becomes a difficult task, if it is attempted to generate a single, body fitted grid with proper clustering. The domain decomposition methods, which divide the computational domain into less complex subdomains, are extensively used to decrease the grid generation workload. A domain decomposition technique also allows the use of different solution methods for different subdomains. The objective of this work is to develop a domain decomposition method via overlapping/embedding the component grids, which is to be used by upwind, multigrid, finite volume solution algorithms. A computer code, given the name MaGGiE, …

The Role Of Values In Personality Development, Joanne Peterson

Institute for the Humanities Theses

As an important element of human life, values play a distinctive role in structuring the developing personality. Considerations of this role are discussed from an objective, subjective, and situational perspective, recognized as three known value orientations incorporated into differing personality theories. Initial inquiries suggest that values are not as important as the degree to which an individual commits to a moral life and then employs this viewpoint in sorting through various alternatives to select those beliefs, attitudes and behaviors best reflecting this commitment.

Optical Machine Recognition Of Lower-Case Greek Characters Of Any Size, Ivan X. D. D'Cunha

Electrical & Computer Engineering Theses & Dissertations

An algorithm utilizing a syntactic approach and a criterion based on normalized moments is defined for the reliable, automatic, machine recognition of handwritten and printed Greek characters of any size and font. In this approach a binary image of the character in question is obtained initially; its skeleton is then produced by utilizing a standard thinning algorithm. The classification process then incorporates the topological features of the characters such as existence of closed curves, number of intersections, number and location of free ends, axial symmetry, and the criteria derived from normalized moments to uniquely identify each pattern. Experiments conducted demonstrated …

Nonlinear Solutions To A Two-Layer Quasi-Geostrophic Model Of The Gulf Stream, Eiichi Oka

OES Theses and Dissertations

The Gulf Stream shows a large meander off Cape Hatteras. This is driven by an energy conversion process known as baroclinic instability and observations suggest that nonlinearity is an important part in this process. In order to understand the fundamental role of nonlinearity in baroclinic instability, an inviscid 2-layer quasi-geostrophic model is studied.

The linear solution is obtained by methods of normal mode and Fourier-Laplace transforms. It is found that the set corresponding to the continuous spectrum is null and the set corresponding to the discrete spectrum is complete.

The nonlinear solution is expanded in terms of the complete set …

Auditory Feedback And Fitts' Law, Tamara L. Atkinson

Psychology Theses & Dissertations

Previous research on Fitts' Law has concentrated on presenting tracking tasks using visual feedback. The present research investigated the effect of auditory and/or visual feedback with a tracking task. Thirty subjects (15 male, 15 female) performed the tracking task using a mouse control to track a target on a computer monitor. The three feedback conditions included auditory, visual, and auditory/visual. For each condition, the Index of Difficulty was varied and the movement time was measured. It was predicted that the auditory feedback would produce movement times that would conform to Fitts' Law. The results indicted that the auditory condition did …

Navier-Stokes Analysis Of Cold Gas Scramjet Nozzle-Afterbody Flowfields, Walter C. Engelund

Mechanical & Aerospace Engineering Theses & Dissertations

The recent renewal of interest in hypersonic aerodynamics, brought about largely in part due to the development of the National Aerospace Plane (NASP), is resulting in an increased reliance on computational fluid dynamics for flowfield data in this flight regime. The design of the nozzle-afterbody section for a hypersonic transport such as the NASP is currently underway, and is being conducted using both computational fluid dynamics and cold, non-reacting, simulant gas experimental models. In this study, a computational analysis is conducted for the flow through a scramjet nozzle-afterbody test section.

Computations have been performed for a cold gas simulation of …

Application Of Shape Sensitivity Analysis For Computation Of Transient Free-Surface Flows, Frank Nicolas Michel

Mechanical & Aerospace Engineering Theses & Dissertations

Shape sensitivity analysis is introduced into a numerical scheme simulating a transient free-surface flow and applied to the case of a fluid advancing through a bed of cylinders. For this incompressible Newtonian flow, viscous forces are dominant. A penalty function finite element formulation is used to solve the problem. Coordinates of nodes on the moving boundary are chosen as design variables and an analytical formulation of the gradient of the finite element algebraic system, with respect to these variables, is derived.

In a numerical example, the results obtained with and without sensitivity analysis are compared. The efficiency and accuracy of …

Identification And Quantitation Of Volatile Amines In Marine Sediments, Chuen Mei Huang

Chemistry & Biochemistry Theses & Dissertations

Pore waters which were taken from sediments of the Chesapeake Bay were analyzed to determine the presence of volatile amines. A purge-and-trap technique was used to concentrate the amines. Then, following derivatization with heptaflourobutyric anhydride, the HFBA-amines were analyzed by gas chromatography with electron capture detection and with mass spectrometric detection. One secondary amine, diethylamine with a concentration of 0.3-0.6 uM, was found in a total of three pore water samples from cores collected on two different dates. A primary amine, sec-butylamine with a concentration of O. 05 AIM, was also found in one of these same samples. Another primary …

Comparison Of Digital Controllers Used In Magnetic Suspension And Balance Systems, William Allen Kilgore

Mechanical & Aerospace Engineering Theses & Dissertations

Dynamic systems that were once controlled by analog circuits are now controlled by digital computers. Presented is a comparison of the digital controllers presently used with magnetic suspension and balance systems. The overall response of the systems are compared using a computer simulation of the magnetic suspension and balance system and the digital controllers. The comparisons include responses to both simulated force and position inputs. A preferred digital controller is determined from the simulated responses.

Non-Linear Dynamics And Control For Thermal Room Models, Milind Prabhakar Oak

Mechanical & Aerospace Engineering Theses & Dissertations

Heating, Ventilation and Air Conditioning (HVAC) building operations with emphasis on reduced energy costs and occupant comfort require a dynamic control of short response (minutes) elements of HVAC systems. Hence, it is imperative to acquire better methods of non-linear modeling for prescription of thermal controls which will regulate space conditions over wide parameter ranges without undue cycling or steady state errors. A first step towards this goal is identification and inclusion of short response dynamics elements in the HVAC systems model while retaining essential non-linearities. A single zone environmental chamber is modeled in the heating mode. In the model, …

An Analysis Of Selected Family Life Education Curricula, Phoebe Terry Butler

Community & Environmental Health Theses & Dissertations

The purpose of this study was to examine the content of family life education curricula in Virginia's public schools and determine its appropriateness for the mentally handicapped students. It was the intent of this study to determine if existing curricula were designed to address the needs of mentally handicapped students according to a standard curricula designed by the American Association for Health, Physical Education and Recreation and the Sex Information and Education Council of the United States. The 15 participants of this study were selected from a random sample of 69. The response rate was 20.2%.

A letter soliciting family …

On The Unique Tree Representation Of Graphs, Beverly Jamison

Computer Science Theses & Dissertations

This dissertation investigates classes of graphs which admit tree representations unique up to isomorphism. The definitions of these classes are based on local properties of P₄'s, A template structure theorem is given which illustrates the nature of the local properties. The template theorem is instantiated for three different classes of graphs. Properties specific to each of the classes are used to produce a tree representation which can be used for graph computations, such as efficient resolution of graph isomorphism. Linear time algorithms for the recognition of three classes of graphs and for the construction of their tree representations …

Identification And Ranking Of Stressors In Nuclear Medicine Technology, Scott R. Sechrist

Community & Environmental Health Theses & Dissertations

The purpose of this study was to identify the most significant stressors in the field of nuclear medicine technology. A sample of convenience of 25 nuclear medicine technologists was used to generate a list of 35 stressors specific to the occupation. Sixty-three randomly selected nuclear medicine technologists responded to a mailed questionnaire which asked the technologist to assess the relative stressfulness of each of the 35 items on a scale of "0 to 1000". Data from the 59 valid responses indicated that equipment malfunctions, add on exams, uncooperative physicians, lack of staff, and uncooperative patients were the most significant stressors …

The Remipedia (Crustacea): A Study Of Their Reproduction And Ecology, Jill Yager

Biological Sciences Theses & Dissertations

Remipedes are an unusual group of troglobitic crustaceans that live exclusively in anchialine caves. Since their discovery in 1979, nine species have been described, seven of which are found in caves in the West Indies, one from the Yucatan peninsula of Mexico and one from the Canary Islands. Most of what is known about these animals has come mainly from taxonomic descriptions. Little has been published about their reproductive biology or ecology. The objectives of this dissertation were to investigate the reproductive biology and ecology of the remipedes inhabiting Sagittarius Cave on Grand Bahama Island, Bahamas.

Sagittarius Cave was chosen …

Microwell Based Competitive Enzyme Immunoassay For Quantifying Serum Triiodothyronine And Thyroxine Levels, Yiwen Yang

Chemistry & Biochemistry Theses & Dissertations

A microwell based competitive enzyme immunoassay for determination of total thyroxine and triiodothyronine in human serum was developed with use of horseradish peroxidase conjugate. The assay, which can be performed in only 1.5 hours at room temperature, involves simultaneous incubation of T₃- or T₄- HRPO conjugate and serum sample in anti-T₃ or anti-T₄ gamma globulin fraction coated polystyrene microwells.

Isolation of anti-T₃ and anti-T₄ gamma globulin fractions were accomplished from whole antiserum by using DEAE-cellulose chromatograph. A carbodiimide coupling method was described to prepare the T₄- and T₃-HRPO …

Mounting Sex Pheromone: A Novel Pheromone Responsible For Mate Recognition In The Ixodidae, Jgc Hamilton

Theses and Dissertations in Biomedical Sciences

Cholesterol oleate was demonstrated to be the cuticular contact sex pheromone of Dermacentor variabilis. This pheromone which has been termed the Mounting Sex Pheromone (MSP) was also demonstrated to be present on the surface of D. andersoni, Amblyomma maculatum and A. americanum. This contact sex pheromone enables males excited and attracted by 2,6-dichlorophenol to identify the female as a potential mating partner. The MSP is the second in the series of three sex pheromones guiding the hierarchy of behavioral responses which constitute tick courtship behavior. Tests with D. variabilis and D. andersoni showed that this pheromone …

Detection Of Outliers And Influential Observations In Regression Models, Anwar M. Hossain

Mathematics & Statistics Theses & Dissertations

Observations arising from a linear regression model, lead one to believe that a particular observation or a set of observations are aberrant from the rest of the data. These may arise in several ways: for example, from incorrect or faulty measurements or by gross errors in either response or explanatory variables. Sometimes the model may inadequately describe the systematic structure of the data, or the data may be better analyzed in another scale. When diagnostics indicate the presence of anomalous data, then either these data are indeed unusual and hence helpful, or contaminated and, therefore, in need of modifications or …

Simultaneous Determination Of 3-Methoxy-4-Hydroxyphenyl-Glycol, Homovanillic Acid, And 5-Hydroxyindoleacetic Acid In Plasma By High Performance Liquid Chromatography, Yung-Te Tseng

Chemistry & Biochemistry Theses & Dissertations

A rapid, reliable, and sensitive method for simultaneous determination of 3-methoxy-4-hydroxyphenylglycol (MHPG), Homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5- HIAA) in plasma is described. The method is based on high performance liquid chromatography with electrochemical detection. Samples were filtered with Amicon Centrifree micropartition systems and extracted with organic solvent before chromatography. Chromatographic separation of sample components was achieved isocratically in a C18 reverse-phase column. Quantitation was performed by measuring the peak height ratios of the sample components to an internal standard. Analytical recoveries ranged from 50.78 (SD 4.2%) to 67.94 (SD 3.28). Within-run coefficient of variations (CVs) ranged from 3.78 …

Best Approximation With Geometric Constraints, Yuesheng Xu

Mathematics & Statistics Theses & Dissertations

This is a study of best approximation with certain geometric constraints. Two major problem areas are considered: best L_p approximation to a function in L_p (0,1) by convex functions, (m, n)-convex functions, (m, n)-convex functions and (m, n)-convex splines, for 1 < p < ∞ , and best uniform approximation to a continuous function by convex functions, quasi-convex functions and piecewise monotone functions.

Software Reliability Models, Syed Afzal Hossain

Mathematics & Statistics Theses & Dissertations

The problem considered here is the building of Non-homogeneous Poisson Process (NHPP) model. Currently existing popular NHPP process models like Goel-Okumoto (G-O) and Yamada et al models suffer from the drawback that the probability density function of the inter-failure times is an improper density function. This is because the event no failure in (0, oo] is allowed in these models. In real life situations we cannot draw sample(s) from such a population and also none of the moments of inter-failure times exist. Therefore, these models are unsuitable for modelling real software error data. On the other hand if the density …

Spatiality In Ulysses And Cubism, Lingchei Chen

English Theses & Dissertations

The paper is a study of James Joyce's Ulysses and Cubism in modern art. Both forms, as the paper presents, use similar techniques to establish multidimensionality in the work of art. In a spatial novel like Ulysses, because of its techniques, the reader is allowed to experience exactly what the characters experience as Joyce presents every aspect of the Dublin life simultaneously. A Cubist painting does the same. As the Cubist painter captures every side of the object and simultaneously presents these different views on the canvas, the spectator is therefore able to apprehend the object from every possible angle, …

The Use Of Rhythm In The Acquisition Of Motor Skills, Ann C. Fulop

Psychology Theses & Dissertations

This research assessed whether rhythm aids in the acquisition of motor skills by providing cues for the timing of those skills. The nature of representations of rhythms in memory was also explored. Certain rhythms have stable memory representations, while others have unstable representations. It was hypothesized that rhythms that had stable memory representations would be more beneficial in learning a skill than unstable rhythms. Three groups learned three different rhythms by practicing a tracking task. Three different tracks displayed the three rhythms. Following training, subjects attempted to reproduce the rhythms from memory. The results suggest that rhythms do help in …

The Geomorphology And Surficial Geology Of The West Flank Of The Blue Ridge, Sherando Area, Virginia, Derek Weston Ryter

OES Theses and Dissertations

The west flank of the Blue Ridge near Sherando, Virginia (Augusta County) consists of many landforms including talus slopes, bedrock cliffs, boulder streams, colluvial slopes, residual knobs, and debris fans. The purpose of this study is to describe the geomorphic history of the area by understanding the spatial and temporal relationships between landforms on the hillslopes.

Boulder streams (maximum 30 m wide, 400 m long, 6.1 m thick) exhibit a gently dipping imbricated fabric and basal shear stresses of 0.1 to 0.4 bars.

Debris fans in Group L (lower) and Group U (upper) are distinguished by topographic position, degree of …

The Temporal And Spatial Distribution Of Blue Crab Larvae On The Mid-Atlantic Bight Adjacent To The Chesapeake Bay, 1982-1983, Lyle Michael Varnell

OES Theses and Dissertations

Recruitment processes are important information for the management of commercially and recreationally exploited marine species. Recruitment processes of the Chesapeake Bay's most important commercial and recreational species, the blue crab, are unknown, due in part to the lack of knowledge of the processes directly preceeding recruitment.

The present study was undertaken to investigate and explain the movement and developmental patterns of blue crab larvae while offshore. Interannual and intraseasonal variations of these patterns were also examined.

Sampling occurred from May to November during 1982 and 1983. Larvae were collected at three depths (neuston layer (upper 10 cm), one meter and …

Picoplankton/Phytoplankton Dynamics In Hampton Roads, Virginia, Leslie E. Dorworth

OES Theses and Dissertations

The biomass distribution of the three main size components of the phytoplankton (net, nano, and picoplankton) was examined in the lower Chesapeake Bay. Work was done at two stations during the spring and neap tidal cycles when freshwater flow into the bay was at its seasonal minimum and maximum. Emphasis was placed on how the picoplankton ( < 2.0 μm, > 0.2 μm) reacted during the sampling period.

Picoplankton made up approximately 13% of the total biomass, during the observed time period, at the more oceanic station. The picoplankton fraction contributed up to 16% of the total biomass at the estuarine station. From this …

Stability Design Of A Slender Column With Curved Longitudinal Stiffeners, Mark S. Lake

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis presents the results of a stability design study of a slender column with curved longitudinal stiffeners for large space structure applications. The stiffened column concept is attractive because it allows the buckling load of a slender column to be increased at a fairly low cost in increased mass, and at no change in the column packaged size. Linear stability analyses are performed using a "linked-plate" representation of the stiffeners to determine stiffener local buckling stresses. Results from a set of parametric analyses are used to determine an approximate explicit expression for stiffener local buckling in terms of its …