Digital Commons Network^™

Growth Characteristics Downstream Of A Shallow Bump: Computation And Experiment, Ronald D. Joslin, Chester E. Grosch

CCPO Publications

Measurements of the velocity field created by a shallow bump on a wall revealed that an energy peak in the spanwise spectrum associated with the driver decays and an initially small-amplitude secondary mode rapidly grows with distance downstream of the bump. Linear theories could not provide an explanation for this growing mode. The present Navier-Stokes simulation replicates and confirms the experimental results. Insight into the structure of the flow was obtained from a study of the results of the calculations and is presented.

An Optimal Path Cover Algorithm For Cographs, R. Lin, S. Olariu

Computer Science Faculty Publications

The class of cographs, or complement-reducible graphs, arises naturally in many different areas of applied mathematics and computer science. In this paper, we present an optimal algorithm for determining a minimum path cover for a cograph G. In case G has a Hamiltonian path (cycle) our algorithm exhibits the path (cycle) as well.

Predicting Strategic Orientations Of Public Research Universities In Economic Development: A Test Of The Resource Dependence Model, Steven Rae Hoagland

Theses and Dissertations in Urban Services - Urban Management

This study is an original application of resource dependence theory to research administration at public universities. It examines the extent to which and under what conditions economic development orientations can be predicted by resource dependence theory. Data analyses concentrate on the combined effects of administrative structure and variations in federal financial support on the economic development orientations of public doctorate-granting universities nationwide.

Data were collected from three sources: (a) published data on the research dollar volume of public universities; (b) higher education personnel directories containing information about research offices; and (c) a mailed survey instrument containing four orientations in economic …

Scanning-Tunneling-Microscopy Study Of Pb On Si(111), D. Tang, H. E. Elsayed-Ali, J. Wendelken, J. Xu

Electrical & Computer Engineering Faculty Publications

Scanning-tunneling microscopy has been used to study temperature and coverage dependence of the structure of lead on the Si(111)-7×7 surface. For low Pb coverage, the Pb atoms favored the faulted sites. The ratio between the number of Pb atoms on faulted to unfaulted sites increased after sample annealing. An energy difference of 0.05 eV associated with a Pb atom on these two sites is estimated. The mobility of Pb atoms on Si(111) was observed at a temperature as low as 260°C for a coverage of 0.1 and 1 ML. © 1995 The American Physical Society.

A Diamond Thin Film Flow Sensor, Sacharia Albin, John C. Hagwood, John B. Cooper, David L. Gray, Scott D. Martinson, Michael A. Scott

Electrical & Computer Engineering Faculty Publications

We present the results of theoretical modeling and experimental testing of a diamond thin film sensor for flow studies. It is shown that the high thermal conductivity of a diamond film can enhance the frequency response of the flow sensor. One-dimensional heat diffusion equation was solved using the finite difference method for determining the frequency response. Two different sensor structures were analyzed: a Ni film on a quartz substrate (Ni/Q) and an intermediate layer of diamond film between the Ni film and quartz substrate (Ni/D/Q). The theoretical model predicts a frequency response for the Ni/D/Q sensor higher than that of …

Gender Bias In Selection For Honors Mathematics At Kempsville Middle School, William P. Mcbride

OTS Master's Level Projects & Papers

The following objectives were established to guide the conduct of this research study: 1. To identify the percentage of females enrolled in the general population of the seventh and eighth grades at Kempsville Middle School; 2. To identify the percentage of females enrolled in the seventh and eighth grade honors mathematics courses at Kempsville Middle School; 3. To determine if a significant difference exists between the percentages determine in objectives one and two above; 4. To interview the personnel involved with the honors mathematics selection process and to review it for gender impartiality.

A Study Of Typing Speed And Accuracy Development Using Computer-Based And Typewriter-Based Instruction In A Public High School, Dale Mcpherson

OTS Master's Level Projects & Papers

To evaluate the effect of computer-based versus typewriter-based instruction on keyboarding speed, the following hypotheses were proposed: 1. Students acquire keyboarding speed more quickly using computer-based instruction than using typewriter-based instruction; 2. Students in computer-based keyboarding classes will demonstrate a lower error rate than students in typewriter-based keyboarding classes.

Effects Of Large Aspect Ratios And Fluctuations On Hard X-Ray-Detection In Lower Hybrid Driven Divertor Tokamaks, Linda L. Vahala, George Vahala, Paul Bonoli

Electrical & Computer Engineering Faculty Publications

It is shown that lower hybrid wave scattering from fluctuations plays a critical role in large aspect ratio divertor plasmas even through the edge density fluctuation levels are only at 1%. This is seen in the theoretically calculated electron power-density profiles which can be directly correlated to the standard experimental chordal hard x-ray profiles. It thus seems that fluctuation effects must be included in determining rf current-density profiles.

Compensation And Characterization Of Gallium Arsenide, Randy A. Roush

Electrical & Computer Engineering Theses & Dissertations

The properties of transition metals in gallium arsenide have been previously investigated extensively with respect to activation energies, but little effort has been made to correlate processing parameters with electronic characteristics. Diffusion of copper in gallium arsenide is of technological importance due to the development of GaAs:Cu bistable photoconductive devices. Several techniques are demonstrated in this work to develop and characterize compensated gallium arsenide wafers. The material is created by the thermal diffusion of copper into silicon-doped GaAs. Transition metals generally form deep and shallow acceptors in GaAs, and therefore compensation is possible by material processing such that the shallow …

A Nonlinear Dynamic Method For Supporting Large-Scale Decision-Making In Uncertain Environments, Wayne Woodhams

Engineering Management & Systems Engineering Theses & Dissertations

This research developed a methodology for supporting decision making by reducing uncertainty in decision environments which are too large, dynamic and complex to be treated by traditional quantitative and simulation techniques. These environments are complex because of the free choice associated with human involvement, and the existence of a large number of interrelated factors which influence the outcomes of the decision process. They are dynamic because the ground rules affecting those interrelationships are constantly changing. Uncertainty cannot be treated probabilistically, since identification of a full set of outcomes and factors of influence is not possible.

The venue for the investigation …

Investigation Of The Relationship Between Pelvic Tilt And Unilateral Sacroiliac Pain, Beth-Anne Moody Jones

Rehabilitation Sciences Theses & Dissertations

Low back pain is the nation's leading cause of disability. Differential diagnosis of a low back injwy can be complicated and uncommon disorders can be overlooked. Many of the signs and symptoms related to low back pain may in fact be caused by sacroiliac dysfunction. Reliability of the current clinical tests for detection of sacroiliac involvement has been of concern. Recently more focus has been given to the use of pelvic tilt measurement as a source of clinical information on the sacroiliac joint. The purpose of this study was to examine the correlation of unilateral sacroiliac dysfunction with asymmetrical changes …

Computer Networks And The Teaching Of English As A Second Language: How Networks Affect Second Language Acquisition, Kirstin J. Reed-Perez

English Theses & Dissertations

No abstract provided.

Autonomous Robot Navigation In Unknown Terrains Using Parallel Numerical Artificial Potential Fields, John C. Schneider

Computer Science Theses & Dissertations

We present a new artificial potential field formulation for resolution complete robot navigation that unifies the purely geometric path planning problem with the lower level force control problem. Our formulation is designed for numerical computation over a massively parallel mesh of processors and is responsive to newly discovered terrain features. It does not suffer from many of the problems commonly associated with potential fields and with adequate resolution provides provably correct, collision free convergence to the goal. In addition, our formulation supports many desirable, practical features required for implementation, such as bounded actuator torques, attainable incremental constructability, realizable computation and …

Simulation Of Active Control Of Asymmetric Flows Around Slender Pointed Forebodies, Hazem Sharaf El-Din

Mechanical & Aerospace Engineering Theses & Dissertations

At high angles of attack, the flowfield over slender forebodies becomes asymmetric with substantial side force, which may exceed the available control capability. The unsteady compressible Navier-Stokes equations are used to investigate the effectiveness of different active control methods to alleviate and possibly eliminate the flow asymmetry and the subsequent side force. Although the research work focuses on active control methods, a passive control method has been investigated. The implicit, Roe flux-difference splitting, finite volume scheme is used for the numerical computations. Both locally-conical and three-dimensional solutions of the Navier-Stokes equations are obtained.

The asymmetric flow over five-degree semi-apex angle …

The Influence Of Seawalls On Beach Responses To Storms, Seasonal Transitions And Long-Term Erosion, John Marshall Hazelton

Civil & Environmental Engineering Theses & Dissertations

It has been argued that seawalls have a detrimental effect on the adjacent beaches. These effects may only be noticeable over a period of years or may be short-term effects associated with storms or with seasonal transitions of the beach. Many theories on beach and seawall interaction have been speculative and have lacked actual field or laboratory evidence for their basis.

This study uses four years of monthly and post-storm beach profile data to examine what influences the seawalls at Sandbridge, Virginia have on the adjacent beaches. Long-term effects of the seawalls are analyzed using fourteen years of profile data. …

Development Of A Knowledge-Based System For Wastewater Pipeline Rehabilitation, David Allen Reaves

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this thesis is to study and develop a knowledge-based system to make decisions for the rehabilitation of wastewater pipelines. Development includes justification for the use of an expert system, data acquisition from knowledge experts, program model development, model testing, implementation and future considerations including expansion. The model is developed and implemented using an expert system shell called XIPlus ®.

This knowledge-based system is designed specifically for the Navy Public Works Center Utilities Department at Norfolk Naval Base in Norfolk, Virginia for making decisions for the rehabilitation of the 50-year-old wastewater collection system. Recent sewer collapses and a …

The Current Voltage Characteristics Of Electron Beam Controlled Thin Film Diamond Switches, Christopher Anthony Molina

Electrical & Computer Engineering Theses & Dissertations

The dark current of natural diamond thin films and the induced current due to electron-beam irradiation was measured up to a range of 7000Ncm'. The contact material was aluminum, annealed and unannealed. Switching experiments were performed with electron energies ranging from 70keV to 172keV. The switching results obtained are strongly dependent on the biasing polarity, incident electron energy, and whether the contact is blocking or Ohmic in nature. A simple model which takes traps into consideration allows us to explain the various switching responses. The range of electrons which define, in part, the switch mode was measured for one sample …

An Approach For Representation Of Organizational Mental Models Using System Dynamics, Jörg-Peter Theissen

Engineering Management & Systems Engineering Theses & Dissertations

The concept of mental models has received much attention within recent years, especially within the context of organizational learning. This research is based on and departs from the Organizational Learning Process as developed by Keating, Robinson, and Clemson (1994). That process, which is based on a verbal representation of mental models, does not call forth the kind of change that is desired in Organizational Learning. This research investigates if mental models can be represented in the form of system dynamics models and inquires if this representation is beneficial to the process of Organizational Learning.

The research was designed as a …

Circulation, Fall 1994, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Fall 1994 issue of CCPO Circulation featuring article "Modeling Circulation and Larval Transport in the Chesapeake Bay"

Allied Communications Intelligence And The Monsoon Group, 1943-1945, Christopher G. Stuart

History Theses & Dissertations

The critical weakness of trade between Germany and Japan during the Second World War was exposed in 1943, when, after all other methods had failed, the Axis powers resorted to submarines as their main means of transportation. The Allied powers succeeded in disrupting the submarines, which the Germans called the Monsoon group. The Allies used communications intelligence to disrupt the Monsoon group in the Atlantic and Indian Oceans. Recently released United States Armed Forces LTRA decrypts, MAGIC messages and their summaries, and Selected Research Histories (SRH) provide the previously top secret details.

Biofeedback Gait Training Auditory Vs. Visual Techniques, Timothy D. Hiemenz

Electrical & Computer Engineering Theses & Dissertations

Training lower extremity amputees to walk normally is quite a difficult task. Amputees must wear a prosthesis so they can walk at all. This allows them some mobility, but their walking pattern may be unnatural. If their gait is temporally asymmetric, they need to exert more energy to move about. This research was initiated to help lower extremity amputees to walk more efficiently using biofeedback gait training. Two types of feedback were developed and tested to determine which method gave the most understandable feedback, validating its use in a clinical setting.

A normal gait cycle uses the lower limbs to …

Defining Locally Shared Memory Constructs For Special Purpose Parallel Architectures, David J. Nielsen

Electrical & Computer Engineering Theses & Dissertations

Locally shared memory systems offer significant advantages over other parallel processing systems for specific classes of problems. Locally shared memory systems tend to be easier to program because explicit passing of messages is not necessary. The goal in defining a locally shared memory system is to allow only a small number of processors access to any single memory. If this goal is met, locally shared memory systems provide an architecture which is relatively simple to implement.

To make shared memory architectures attractive to designers of special purpose parallel architectures, the architectures must be scalable. To be scalable, the number of …

A Study Of The Thermodynamic And Heat Transfer Characteristics Of Two-Phase Two-Component Flow With Application To A Solar-Assisted Heat Pump, Walid A. Aziz

Mechanical & Aerospace Engineering Theses & Dissertations

Two-phase flow of single component refrigerants has been studied, theoretically and experimentally, for many CFCs, in many industrial applications, including the solar-assisted heat pump system. This study extends the thermodynamic and heat transfer analysis in the phase transition boiling region, to newly proposed refrigerant mixtures, which are candidates for replacing the classical CFCs for future HVAC applications. The goal of this study is to develop a methodology, to design the collector/evaporator tubes of a solar-assisted heat pump, using a binary refrigerant mixture as the working fluid. The method is implemented numerically as a computer algorithm. In order to do that, …

Seasonal Phytoplankton Dynamics In The Pagan River, David Wade Seaborn

Biological Sciences Theses & Dissertations

The composition and seasonal abundance patterns for phytoplankton in the Pagan River, Virginia, were determined. This river is characterized as a nutrient enriched system with annual mean levels of total nitrogen and phosphorus at 1.8 and 0.8 mg/I respectively. Three phytoplankton maxima occurred during the year with the highest in fall, followed by summer and spring peaks. A diatom flora was dominant throughout the year at concentrations of 107 to 108 cells/I. Other algal populations exhibited distinct periods of abundance, which seasonally varied in magnitude and time of development. Turbidity levels were high throughout the year, with a mean secchi …

African-American Women's Career Development: Predicting Nontraditional Educational And Career Choices Educational And Career Aspirations And Career Salience, Tonya Alicia Miller

Psychology Theses & Dissertations

The purpose of the current research was to develop and to test a model pertaining to the unique career development experiences of African-American women. The model concentrates on African-American women's educational and career aspirations, educational and career choices, and their career salience. A sample of 183 female African American undergraduate and graduate students from three local universities supplied data for the study. Results of the hierarchical block regression analyses conducted to test the proposed model were mixed. The proposed predictor sets, self-perceptions, career exposure, and relational support, were more strongly related to educational aspirations, career choice, and career salience, than …

The Effect Of Same-Sex Grouping Versus Mixed-Sex Grouping On Mathematics Achievement And Attitudes Of Academically Gifted Fourth And Fifth Grade Females In The Urban Classroom, Martha J. Tompkins

Theses and Dissertations in Urban Studies

Reports of the neglect of gifted students in America's schools and the inadequate mathematics involvement of females have made educators aware of a crisis in public education. Attitudes and opportunities are believed to be major influences in helping females become more involved with mathematics courses and careers. The research project examined the effect of same-sex groups versus mixed-sex groups on mathematics attitudes and achievement in fourth and fifth grade females in a mathematically gifted pilot program at a magnet center. The experimental study was analyzed with Multivariate Analysis of Variance (MANOVA), Analysis of Variance (ANOVA), Regression Analysis, Post-Hoc tests, and …

Radiative Interactions In Multi-Dimensional Chemically Reacting Flows Using Monte Carlo Simulations, Jiwen Liu

Mechanical & Aerospace Engineering Theses & Dissertations

The Monte Carlo method (MCM) is applied to analyze radiative heat transfer in nongray gases. The nongray model employed is based on the statistical narrow band model with an exponential-tailed inverse intensity distribution. The amount and transfer of the emitted radiative energy in a finite volume element within a medium are considered in an exact manner. The spectral correlation between transmittances of two different segments of the same path in a medium makes the statistical relationship different from the conventional relationship, which only provides the noncorrelated results for nongray analysis. Two features of the MCM that are different from other …

Investigation Of Computational And Spectral Analysis Methods For Aeroacoustic Wave Propagation, Florence Odile Vanel

Mechanical & Aerospace Engineering Theses & Dissertations

Most computational fluid dynamics (CFD) schemes are not adequately accurate for solving aeroacoustics problems, which have wave amplitudes several orders of magnitude smaller yet with frequencies larger than the flow field variations generating the sound. Hence, a computational aeroacoustics (CAA) algorithm should have minimal dispersion and dissipation features. A dispersion relation preserving (DRP) scheme is, therefore, applied to solve the linearized Euler equations in order to simulate the propagation of three types of waves, namely: acoustic, vorticity, and entropy waves. The scheme is derived using an optimization procedure to ensure that the numerical derivatives preserve the wave number and angular …

Circulation, Summer 1994, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Summer 1994 issue of CCPO Circulation featuring article "Large Influences From Small Features: Submarine Canyons"

An Assessment Of Personal Characteristics, Job Satisfaction And Semantic Descriptors Of Virginia Acute And Tertiary Care Hospitals' Chief Executive Officers, Justin C. Matus

Health Services Research Dissertations

The purpose of the study was to identify the determinants of job satisfaction of Virginia Hospital CEO's and to identify those descriptors that best characterize the role of the hospital CEO as defined by the CEO's themselves. The study sample consisted of all hospital CEO's in Virginia as listed by the Virginia Hospital Association. The study employed a four part survey instrument that investigated four major areas: (1) personal and hospital demographics; (2) self rated performance; (3) a semantic scale measuring the concept of Hospital CEO; and (4) The Minnesota Satisfaction Questionnaire. A survey was mailed to 119 CEO's. The …