Digital Commons Network^™

Resource Utilization Model For The Algorithm To Architecture Mapping Model, Rakesh R. Patel

Electrical & Computer Engineering Theses & Dissertations

The analytical model for resource utilization, and the variable node time and conditional node model for the enhanced ATAMM model for a real-time data flow architecture, is presented in this research. The Algorithm To Architecture Mapping Model, ATAMM, is a Petri net based graph theoretic model developed at Old Dominion University, and is capable of modeling the execution of large-grained algorithms on a real-time data flow architecture. Using the resource utilization model, the resource envelope may be obtained directly from a given graph and, consequently, the maximum number of required resources may be evaluated. The node timing diagram for one …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone, John Roland Moisan

OES Theses and Dissertations

Two time- and space-dependent, physical-bio-optical models have been developed for the California Coastal Transition Zone (CTZ) region with the overall objective of understanding and quantifying the processes th at contribute to the spatial and temporal development of nutrient and plankton distributions in the CTZ. The first of these models considers only time- and vertical processes at specific locations in the CTZ. The model food web components include: silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids and a detritus pool. The wavelength dependent attenuation of the subsurface irradiance field, due to sea water, phytoplankton pigment concentrations and dissolved organic …

Measurement Of The Casimir-Polder Force, C. I. Sukenik, M. G. Boshier, S. Cho, V. Sandoghdar, E. A. Hinds

Physics Faculty Publications

The authors have studied the deflection of ground-state sodium atoms passing through a micron-sized parallel-plate cavity by measuring the intensity of a sodium atomic beam transmitted through the cavity as a function of cavity plate separation. This experiment provides clear evidence for the existence of the Casimir-Polder force, which is due to modification of the ground-state Lamb shift in the confined space of a cavity. The results confirm the magnitude of the force and the distance dependence predicted by quantum electrodynamics.

Strong Large Deviation And Local Limit Theorms, Narasinga Rao Chaganty, Jayaram Sethuraman

Mathematics & Statistics Faculty Publications

Most large deviation results give asymptotic expressions for log P(Y_n ≥ y_n), where the event {Y_n ≥ y_n} is a large deviation event, that is, P(Y_n ≥ y_n) goes to 0 exponentially fast. We refer to such results as weak large deviation results. In this paper we obtain strong large deviation results for arbitrary random variables {Y_n}, that is, we obtain asymptotic expressions for P(Y_n ≥ y_n), where {Y_n ≥ y_n} is a large deviation event. These strong large deviation results …

The Sharp Lipschitz-Constants For Feasible And Optimal-Solutions Of A Perturbed Linear Program, Wu Li

Mathematics & Statistics Faculty Publications

The purpose of this paper is to derive the sharp Lipschitz constants for the feasible solutions and optimal solutions of a linear program with respect to right-hand-side perturbations. The Lipschitz constants are given in terms of pseudoinverses of submatrices of the matrices involved and are proven to be sharp.

Paschen's Law For A Hollow Cathode Discharge, H. Eichhorn, K. H. Schoenbach, T. Tessnow

Bioelectrics Publications

An expression for the breakdown voltage of a one‐dimensional hollow cathode discharge has been derived. The breakdown condition which corresponds to Paschen’s law contains, in addition to the first Townsend coefficient, and the secondary electron emission coefficient two parameters which characterize the reflecting action of the electric field and the lifetime of the electrons in the discharge. The breakdown voltage for a hollow cathode discharge in helium was calculated and compared to that of a glow discharge operating under similar conditions.

A Magnetic Suspension System With A Large Angular Range, Colin P. Britcher, Mehran Ghofrani

Mechanical & Aerospace Engineering Faculty Publications

In order to explore and develop technology required for the magnetic suspension of objects over large ranges of orientation, a small-scale laboratory system, the large-angle magnetic suspension test fixture (LAMSTF) has been constructed at NASA Langley Research Center. This apparatus falls into the category of large-gap, actively stabilized magnetic levitation systems. The hardware comprises five conventional electromagnets in a circular arrangement, each driven from a separate bipolar power amplifier. Electromagnet currents are commanded by a digital control system, implemented on a microcomputer, which in turn derives the position and attitude of the suspended element from an infrared optical system. The …

Glow-Discharge Enhanced Permeation Of Oxygen Through Silver, D. Wu, R. A. Outlaw, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The permeation of oxygen through Ag0.05Zr over the temperature range of 300-650°C under glow-discharge conditions has been studied and compared to the permeation of thermally dissociated molecular oxygen. A low-energy dc glow-discharge in O₂ has been employed which produced approximately 10% atoms. The permeation rate during the glow discharge was found to be much higher (a factor of ∼10) than without the glow discharge. The small fraction of oxygen atoms generated appears to dominate the permeation because of much higher solution probabilities. Below 500°C, the activation energy for the permeation with glow discharge was found to be 15.5 kcal/mol …

Environmental Effects On The Growth And Development Of Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), Larvae: A Modeling Study, Margaret M. Dekshenieks, Eileen E. Hofmann, Eric N. Powell

CCPO Publications

The effects of temperature, food concentration, salinity and turbidity on the growth and development of Crassostrea virginica larvae were investigated with a time-dependent mathematical model. Formulations used in the model for larval growth are based upon laboratory data. Simulations were done using temperature conditions characteristic of Laguna Madre, Galveston Bay, Apalachicola Bay, North Inlet and Chesapeake Bay. These simulations show that the duration of the planktonic larval phase, which is determined by larval growth rate, decreases at lower latitudes in response to warmer water temperatures. Also, oysters in the more southern locations have a longer spawning season during which the …

A Study To Determine If Ged Classes Helped Students To Gain Employment And Build Self-Esteem, Diane J. Calhoun

OTS Master's Level Projects & Papers

The objectives of this study were to determine: 1. If GED classes were adequately preparing students to compete in the high-tech, competitive job market; 2. If GED classes are building student self-esteem.

A Study To Determine If Telecommunications Can Be Used As A Medium To Teach Basic Literacy Skills To Illiterate Adults In Virginia, Joan Hairston Jones

OTS Master's Level Projects & Papers

The following goals were selected to guide this study: 1. Determine which methods have been used and how successful they have been in the past to teach basic literacy skills to illiterate adults; 2. Determine the methods currently being used to supplement classroom instruction; 3. Determine how receptive adults are to self-paced, self-directed methods; 4. Determine the type of problems experienced using telecommunications to teach literacy skills.

A Study To Determine The Effectiveness Of Manipulative Mathematics On Student Learning Outcomes As Compared To Textbook Practices, Cheryl F. Robinson

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 the manipulative mathematics curriculum as compared to those who were exposed only to textbook practices.

Scans-Identified Employment Skills And Hampton Roads Employers, Glennon J. Lovett

OTS Master's Level Projects & Papers

There were three goals of this research study: 1) Examine the basic employment skills required by employers; 2) Examine the basic employment skills identified in the SCANS report; 3) Examine the correlation between employer identified skills and the skills outlined in the SCANS report.

A Study To Determine The Correlation Between The Virginia Common Core Of Learning And The Secretary's Commission On Achieving Necessary Skills Reports To The Marketing Education Curriculum, Lalita Brinkley Samrai

OTS Master's Level Projects & Papers

The problem of this study was to determine the correlation between the Virginia Common Core of Learning and the Secretary's Commission on Achieving Necessary Skills Reports to the marketing education curriculum in Newport News. The research goals of the study were 1) to determine how Marketing Education Curriculum compares to the outcomes identified in the Virginia Common Core of Learning; 2) to determine how the Marketing Education Curriculum compares with the Secretary's Commission on Achieving Necessary Skills Report; and 3) to develop a plan to improve the Marketing Curriculum to meet the demands of society.

A Study To Determine What Knowledge, Skills And Abilities Chesapeake Marketing Education Students Should Possess In Order To Fulfill The Needs Of Retailers In Chesapeake, Virginia, Stephanie L. Freeman

OTS Master's Level Projects & Papers

To find a solution to the problem, the following questions had to be answered: 1. What background knowledge should Marketing Education students display before applying for a retail job? 2. What specific skills should Marketing Education students possess? 3. What abilities should Marketing Education students be able to perform without extemporization? 4. What additional needs do retailers have of Marketing Education students?

A Study To Determine The Correlation Between School Attendance And The Passing Rate On The Virginia Literacy Passport Test At Rosemont Middle School 1990-1992, Victoria R. Porter

OTS Master's Level Projects & Papers

Examination of the following questions established a relationship between school attendance and the passing rater of the test: 1. Did students with high attendance records earn higher test scores? 2. Did students with low school attendance records earn lower test scores? 3. Is there a relationship between Literacy Passport Test Scores and school attendance?

Direct Measurements Of The Transport Of Nonequilibrium Electrons In Gold Films With Different Crystal Structures, T. Juhasz, H. E. Elsayed-Ali, G. O. Smith, C. Suárez, W. E. Bron

Electrical & Computer Engineering Faculty Publications

The transport of femtosecond-laser-excited nonequilibrium electrons across polycrystalline and single-crystalline gold films has been investigated through time-of-flight measurements. The thicknesses of the films range from 25 to 400 nm. Ballistic electrons as well as electrons interacting with other electrons and/or with the lattice have been observed. The ballistic component dominates the transport in the thinner films, whereas the interactive transport mechanism is dominant at the upper end of the thickness range. A slower effective velocity of the interactive component is observed in the polycrystalline samples, and is assumed to arise from the presence of grain boundaries. The reflection coefficient of …

A Numerical Study Of Wave Propagation In A Confined Mixing Layer By Eigenfunction Expansions, Fang Q. Hu

Mathematics & Statistics Faculty Publications

It is well known that the growth rate of instability waves of a two-dimensional free shear layer is reduced greatly at supersonic convective Mach numbers. In previous works, it has been shown that new wave modes exist when the shear layers are bounded by a channel due to the coupling effect between the acoustic wave modes and the motion of the mixing layer. The present work studies the simultaneous propagation of multiple stability waves using numerical simulation. It is shown here that the coexistence of two wave modes in the flow field can lead to an oscillatory growth of disturbance …

Temporal Model Of An Optically Pumped Co-Doped Solid State Laser, T. G. Wangler, J. J. Swetits, A. M. Buoncristiani

Mathematics & Statistics Faculty Publications

Currently, research is being conducted on the optical properties of materials associated with the development of solid-state lasers in the 2 micron region. In support of this effort, a mathematical model describing the energy transfer in a holmium laser sensitized with thulium is developed. In this paper, we establish some qualitative properties of the solution of the model, such as non-negativity, boundedness, and integrability. A local stability analysis is then performed from which conditions for asymptotic stability are obtained. Finally, we report on our numerical analysis of the system and how it compares with experimental results.

The Scattering Potential For A Polytrope Of Degree-5, J. A. Adam

Mathematics & Statistics Faculty Publications

By regarding the study of radial and non-redial stellar oscillations as a problem in potential scattering theory, a standard form of the radial Schrödinger equation can be derived. After establishing some preliminary results of astrophysical interest, an analytic expression for the potential is derived for a truncated (i.e., finite radius) polytrope (or class of self-gravitating compressible spheres) of degree n = 5. Properties of the potential are discussed.

Age, Growth, And Reproduction Of Tautog Tautoga Onitis (Labridae: Perciformes) From Coastal Waters Of Virginia, E. Brian Hostetter, Thomas A. Munroe

Biological Sciences Faculty Publications

Tautog Tautoga onitis are gaining popularity in Virginia's coastal waters as a recreational and food fish. Adult tautog are seasonally abundant on inshore hard-bottom habitats (1-10 m) and inhabit offshore areas (10-75 m) year-round. Juveniles, especially newly-settled recruits, inhabit vegetated areas in shallow water (usually < 1 m). From March 1979 to July 1986, tautog were collected in lower Chesapeake Bay and nearby coastal waters to examine age, growth, and sexual maturation. Age estimates were determined from annular marks on opercle bones: 82% of the fish were age-10 or younger, 18% exceeded age-10, and 1% were age-20 or older. Marginal increment analysis revealed that annuli formed concurrent with a protracted spawning season (April-July). The von Bertalanffy growth equation, derived from back-calculated mean lengths-at-age, was l(t) = 742 [1-e-0.085 (t-1.816)]. Tautog are long-lived (25+ yr) and attain relatively large sizes (672 mm TL) slowly (K for sexes combined = 0.085). Growth rates of both sexes are similar, although males grow slightly faster (K = 0.090 vs. 0.085 for females). Maturity occurs at age-3 in both sexes. Growth rates for tautog from Virginia are similar to those reported nearly 25 years ago for tautog in Rhode Island. Growth rates for tautog are similar to those of other reef fishes, such as snappers and groupers. Habitat restriction, slow growth, great longevity, and increasing popularity by user groups may contribute to over-exploitation of this species in Virginia waters.

Phytoplankton Relationships To Water Quality In Lake Drummond And Two Drainage Ditches, Christine G. Phillips, Harold G. Marshall

Biological Sciences Faculty Publications

A twelve-month phytoplankton study was conducted in Lake Drummond and Washington and Jericho Ditches from December 1988 to November 1989. Four dominant phytoplankton groups were identified at these sites. These were the Bacillariophyceae, Cyanophyceae, Cryptophyceae and an autotrophic picoplankton component. Over the past 20 years there has been a decrease in the mean pH levels of Lake Drummond and the replacement of one its former major components, the Chlorophyceae, by the Cyanophyceae. Based on water quality analysis results and species diversity indices, Lake Drummond is classified as in an early eutrophic stage of development.

Induced Mach Wave-Flame Interactions In Laminar Supersonic Fuel Jets, F. Q. Hu, T. L. Jackson, D. G. Lasseigne, C. E. Grosch

Mathematics & Statistics Faculty Publications

A model problem is proposed to investigate the steady response of a reacting, compressible laminar jet to Mach waves generated by wavy walls in a channel of finite width. The model consists of a two-dimensional jet of fuel emerging into a stream of oxidizer which are allowed to mix and react in the presence of the Mach waves. The governing equations are taken to be the steady parabolized Navier-Stokes equations which are solved numerically. The kinetics is assumed to be a one-step, irreversible reaction of the Arrhenius type. Two important questions on the Mach wave-flame interactions are discussed: (i) how …

Studies Of Electron-Beam Penetration And Free-Carrier Generation In Diamond Films, R. P. Joshi, K. H. Schoenbach, C. Molina, W. W. Hofer

Bioelectrics Publications

Experimental observations of the energy‐dependent electron‐beam penetration in type II‐A natural diamond are reported. The experimental data are compared with results obtained from numerical Monte Carlo simulations, and the results are in very good agreement. The results also reveal that a threshold energy of about 125 keV is necessary for complete penetration for a 35 μm sample. It is found that over the 30–180 keV range, the energy dependence of the penetration depth and total path length exhibits a power‐law relation. Monte Carlo simulations have also been performed to investigate the excess carrier‐generation profiles within diamond for a set of …

A Comparison Of Gulf Stream Sea Surface Height Fields Derived From Geosat Altimeter Data And Those Derived From Sea Surface Temperature Data, Tal Ezer, George L. Mellor, Dong-Shan Ko, Ziv Sirkes

CCPO Publications

Two types of satellite data, Geosat altimeter data and sea surface temperature data (SST), are compared and evaluated for their usefulness in assimilation into a numerical model of the Gulf Stream region. Synoptic sea surface height (SSH) fields are derived from the SST data in the following way: first three-dimensional temperature and salinity analysis fields are obtained through the Optimum Thermal Interpolation System (OTIS), and then SSH fields are calculated using a primitive equation, free-surface, numerical model running in a diagnostic mode. The aforementioned SSH fields are compared with SSH fields obtained from the Geosat altimeter data. Use of Geosat …

Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen

Bioelectrics Publications

The temporal development of the electric field distribution in semi‐insulating GaAs photoconductive switches operated in the linear and lock‐on mode has been studied. The field structure was obtained by recording a change in the absorption pattern of the switch due to the Franz–Keldysh effect at a wavelength near the band edge of GaAs. In the linear mode, a high field layer develops at the cathode contact after laser activation. With increasing applied voltage, domainlike structures become visible in the anode region and the switch transits into the lock‐on state, a permanent filamentary electrical discharge. Calibration measurements show the field intensity …

The Dynamics Of Growth-Factor-Modified Immune-Response To Cancer Growth: One-Dimensional Models, J. A. Adam

Mathematics & Statistics Faculty Publications

By characterizing the effect of tumor growth factors as deviations from normal logistic-type growth rates, the spatio-temporal dynamics for a one-dimensional model of cancer growth incorporating immune response are studied. The growth rates considered are classified respectively as normal, activated, inhibited and delay activated. The homogeneous steady states are defined by relative extrema of a ''free energy'' function V(x) for each of the above four cases. This function is of particular importance in studying the coexistence of tumoral and cancer-free steady states, and in identifying the nature (progressive or regressive) of travelling wave solutions to the nonlinear partial differential equation …

Reliability Trend Analyses With Statistical Confidence Limits Using The Luke Reliability Trend Chart, Stephen R. Luke

Engineering Management & Systems Engineering Theses & Dissertations

In electronic systems, it is interesting to understand exactly how the reliability is changing with time. Dynamic performance changes when a system passes from infant mortality stage into useful life phase and when the system passes from useful life phase into wearout phase. Dynamic performance also changes when the system is redesigned or when the system is acted on by a number of other outside forces such as a change in maintenance policy, escalation of alignment problems, or a change in training program. It is important to know when a system is changing dynamically in order to assess design, policy …

Heat Storage And Transport Processes In The Tropical Atlantic Ocean, Andras Kapolnai

OES Theses and Dissertations

Heat storage and transport processes of the tropical Atlantic play an important role in the climate of three continents. The exploration of how the warm water mass maintenance in the equatorial basin depends on various external factors is therefore an important task. This study examines the annual cycle of the warm water mass formation and its transport in the equatorial Atlantic through the interaction of the atmospheric and oceanic boundary layers. Key features of the model are the sea level wind field, equatorial upwelling rate and escape transport of the formed warm water out of the equatorial basin.

The model …

The Effect Of Noncognitive Variables On The Prediction Of Academic Difficulty And Attrition Of Freshman Student-Athletes, Bruce W. Cunningham

Theses and Dissertations in Urban Services - Urban Education

This study identified a set of noncognitive variables, indicators of attitudes, habits, and beliefs as they relate to an individual's educational pursuits, in the form of Probation and Attrition Scores, to be used as alternatives to the exclusive use of cognitive variables to identify freshman student-athletes who are at risk of academic difficulty or attrition. Data were collected at an urban, public university of approximately 17,000 students using the University's Freshman Survey, an instrument that combines a number of scales designed to measure specific sets of noncognitive indicators.

Noncognitive survey data, as well as demographic information and cognitive admissions data, …