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A Generalization Of Linear Multistep Methods, Leon Arriola

Mathematics & Statistics Theses & Dissertations

A generalization of the methods that are currently available to solve systems of ordinary differential equations is made. This generalization is made by constructing linear multistep methods from an arbitrary set of monotone interpolating and approximating functions. Local truncation error estimates as well as stability analysis is given. Specifically, the class of linear multistep methods of the Adams and BDF type are discussed.

Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola

Electrical & Computer Engineering Faculty Publications

The influence of the copper concentration in silicon-doped gallium arsenide on the photoionization and photoquenching of charge carriers was studied both experimentally and theoretically. The studies indicate that the compensation ratio (N_Cu/N_Si) is an important parameter for the GaAs:Si:Cu switch systems with regard to the turn-on and turn-off performance. The optimum copper concentration for the use of GaAs:Si:Cu as an optically controlled closing and opening switch is determined.

Electrical Properties Of Hydrogenated Diamond, Sacharia Albin, Linwood Watkins

Electrical & Computer Engineering Faculty Publications

Hydrogen passivation of deep traps in diamond is demonstrated. Current‐voltage (I‐V) characteristics of polycrystalline thin film and bulk diamond were studied before and after hydrogenation. On hydrogenation, all the samples showed several orders of magnitude increase in conductivity. Hydrogenation was carried out under controlled conditions to study the changes in the I‐V characteristics of the samples. The concentration of uncompensated traps was varied systematically by hydrogenation. The concentration of electrically active hydrogen was determined from the I‐V data. It is shown that hydrogenation is an alternative to deep‐level transient spectroscopy, suitable for …

Brochure: 12th Annual Literary Festival, 1989, Publications Department, Old Dominion University

12th Annual Literary Festival at ODU: October 2-5, 1989

No abstract provided.

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.

Spire And Tower: The History, Architecture And Art Of Two Norfolk, Virginia Churches, Judith L. Smith

Institute for the Humanities Theses

While St. Mary of the Immaculate Conception Roman Catholic Church and Epworth Methodist Episcopal Church are dissimilar in origin, religious practices, and architectural style, when taken together, their periods of construction in their respective revival styles span and define an important era in Norfolk, Virginia's urban history.

Original research in the sparse records of several Catholic parishes identifies the previously known name of the architect of St. Mary's church. The study also offers additional information on that church's stained glass window.

The author presents the heretofore scattered history of Epworth Church in chronological order. The study develops new information concerning …

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.

The Electrical Characteristics Of Semi-Insulating Gallium Arsenide A Material For High Power Switches, David Clifton Stoudt

Electrical & Computer Engineering Theses & Dissertations

An experimental study of the electrical characteristics of semi-insulating gallium arsenide has been performed. The goal of this research was to aid in the development of an electron-beam controlled high-power semiconductor switch. The electrical characteristics were found to be heavily dependent on the deep level configuration of the material being investigated. Two methods of deep level characterization are discussed and their results are compared to the information given by the material manufacturer. Studies were conducted to determine both the steady-state and transient dark current characteristics of the switch. Along with being a function of the applied voltage and the deep …

The Effects Of Bending On The Strain Distributions In A Stiffener-Skin Interface Region, Osvaldo F. Lopez

Mechanical & Aerospace Engineering Theses & Dissertations

An analytical and experimental study to assess the effect of bending on the adhesive strain distributions in a stiffener-skin interface region is described. A one-dimensional beam analysis is derived using a variational approach. Parametric studies are conducted to assess the effects of stiffener, skin, and adhesive thickness and adhesive material nonlinearity on the adhesive layer extensional and shear strain distributions subjected to applied bending. Two experimental methods of measuring through-the-thickness extensional strains in an adhesive are investigated. One method involves measuring the changes in the resistance of a composite strain sensor subjected to applied tension and compression loads. The second …

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 …

Sojourn: A Time In Egypt, Deborah L. Miller

Institute for the Humanities Theses

This work is a chronicle of events and ideas experienced by the author while traveling in the Arab Republic of Egypt in December, 1986 and January, 1987. The illustrations at each chapter head were drawn to help the reader understand the nature of the story of each chapter.

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 …

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, …

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 …

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 …

Productivity Measurement For Home Health Care Registered Nurses, Lazelle Emminizer Benefield

Theses and Dissertations in Urban Services - Urban Management

The purpose of this study is to develop a productivity measurement applicable to home health registered nurses (RNs) by identifying and quantifying the knowledge and ability variables that define productive nurse practice.

A preliminary set of knowledge and ability variables was identified based on content analysis of interviews with local nurse managers and round I of a three round Delphi procedure, using a purposive sample of nurse managers from nationally preeminent agencies. A randomized national sample of 337 nurse managers was then surveyed to determine the relative value and rank of the knowledge and ability variables. These variables were refined …

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, …

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 …

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 …

Three American Resistance Leaders In The Philippine Islands During World War Ii, Brian W. Mclean

History Theses & Dissertations

This thesis compares the effectiveness of three Americans who led major guerrilla groups against the Japanese in the Philippine Islands during World War II. It is limited to Wendell Fertig on Mindanao, James Cushing on Cebu, and Russell Volckmann on Luzon. Previous works addressed only individual leaders; this thesis compares different leaders.

The thesis concludes that although differences did exist in how each individual officer rose to command, all three were effective in leading resistance efforts against the Japanese. The greatest differences among them were the amount of support they received from MacArthur's General Headquarters Southwest Pacific Area (GHQ SWPA) …

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 …

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 …

Beetle Wings And Other Savory Tidbits, Krystyna Rozanski Stefansky

English Theses & Dissertations

Journalism is not a field in which facts must always be written black on white, opinion deleted. As a writer, largely of features, rather than what editors in my profession call "hard news," I particularly like writing the personal column.

In those 14 inches I can explore issues of the day, take a closer look at my life, family and neighbors, The looks are at some times more thoughtful than at others. Some topics are meant merely to entertain. Others to fuel discussion. All are meant to be gentle examinations of the truth, the tidbits of life that keep all …

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 …

An Assessment Of The Characteristics And Attrition Rates Of Physical Therapist Assistant Educational Programs, Pamela Ann Bayliss

Community & Environmental Health Theses & Dissertations

The purpose of this study was to determine the student attrition rate in physical therapist assistant programs accredited by the American Physical Therapy Association (APTA) at the time of the study and to identify factors which may affect student attrition. The survey instrument was designed to gather data on student attrition rates for the classes which graduated in 1984, 1985, and 1986 and on program characteristics such as admission policies and curricular requirements. The mean student attrition rates were 32%, 28.6%, and 26.4% in 1984, 1985 and 1986, respectively. There were no significant differences identified via Chi Square (p

Articulation Of Practical Nursing Programs To Institutes Of Higher Learning, Gwendolyn T. Sweat

Community & Environmental Health Theses & Dissertations

This study investigated the size of the Practical Nursing schools, the student/faculty ratio, the admission process, the number of program hours as well as individual course hours of each program, specific aspects of articulation agreements in place, and the need for a bridge course and its contents. Also collected was demographic information regarding the students. The study involved the aggregate population of 43 Practical Nursing Programs in Virginia. Study findings, based on responses from 28 schools, included the following: the practical nursing schools are or the most part 18 months long, have three faculty members, admit students in late summer …

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 …

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 …

The Effects Of Life Stress And Risk-Taking Style On Risk Perception And Driver Performance, Christine B. Philput

Psychology Theses & Dissertations

This study examined the effects of risk-taking style, stress level, and highway environment on driver performance. In Phase I, 50 subjects were assessed for risk-taking style and stress level. In Phase II, the same subjects were presented with slides of traffic situations that varied in terms of risk of accident. This was a paired comparison task in which they rank-ordered ten highway sites, producing a measure of subjective risk. No significant relationships were identified between these subjective risk judgments and objective data regarding those sites (accidents and fatalities), though this is most likely due to problems with the slide presentation. …

Numerical Study Of Three-Dimensional Separation And Flow Control At A Wing/Body Junction, Balakrishnan Lakshmanan

Mechanical & Aerospace Engineering Theses & Dissertations

The problem of three-dimensional separation and flow control at a wing/body junction has been investigated numerically using a three-dimensional Navier-Stokes code. The numerical code employs an algebraic grid generation technique for generating the grid for unmodified junction and an elliptic grid generation technique for filleted fin junction. The results for laminar flow past a blunt fin/flat plate junction demonstrate that after grid refinement, the computations agree with experiment and reveal a strong dependency of the number of vortices at the junction on Mach number and Reynolds number. The numerical results for pressure distribution, particle paths and limiting streamlines for turbulent …