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Active And Adaptive Flow Control Of Twin-Tail Buffet And Applications, Zhi Yang

Mechanical & Aerospace Engineering Theses & Dissertations

Modern fighter aircraft with dual vertical tails are operated at high angles of attack. The vortex generated by leading edge extension (LEX) breaks down before reaching the two vertical tails. The wake of highly unsteady, turbulent flow causes unbalanced broadband aerodynamic loading on the tails and may produce severe buffet on the tails and lead to tail fatigue failure.

Flow suction along the vortex cores (FSVC) is investigated as an active control method for tail-buffet alleviation. Suction tubes have been tilted at different angles to study the control effectiveness of suction tubes orientation. Flow field response, aerodynamic loading and aeroelastic …

Federating Heterogeneous Digital Libraries By Metadata Harvesting, Xiaoming Liu

Computer Science Theses & Dissertations

This dissertation studies the challenges and issues faced in federating heterogeneous digital libraries (DLs) by metadata harvesting. The objective of federation is to provide high-level services (e.g. transparent search across all DLs) on the collective metadata from different digital libraries. There are two main approaches to federate DLs: distributed searching approach and harvesting approach. As the distributed searching approach replies on executing queries to digital libraries in real time, it has problems with scalability. The difficulty of creating a distributed searching service for a large federation is the motivation behind Open Archives Initiatives Protocols for Metadata Harvesting (OAI-PMH). OAI-PMH supports …

Dark Production: A Significant Source Of Oceanic Cos, M. Von Hobe, Gregory A. Cutter, A. J. Kettle, M. O. Andreae

OES Faculty Publications

Carbonyl sulfide (COS) in air and dissolved in seawater was determined during a cruise in August 1999 in the Sargasso Sea in the northwest Atlantic Ocean. Dissolved concentrations at the sea surface displayed only a weak diel cycle with a mean of 8.6 ± 2.8 pmol dm⁻³ owing to low abundance of photochemical precursors and high temperatures causing rapid hydrolysis. Depth profiles measured over the oceanic mixed layer revealed significant vertical gradients of COS concentration with higher values at the surface, suggesting that the rate of photochemical production at the surface exceeds the rate of vertical mixing. The mean …

The Standardized Fish Bioassay Procedure For Detecting And Culturing Actively Toxic Pfiesteria, Used By Two Reference Laboratories For Atlantic And Gulf Coast States, Joann M. Burkholder, Harold G. Marshall, David W. Seaborn, Nora J. Deamer-Melia

Biological Sciences Faculty Publications

In the absence of purified standards of toxins from Pfiesteria species, appropriately conducted fish bioassays are the "gold standard" that must be used to detect toxic strains of Pfiesteria slop. from natural estuarine water or sediment samples and to culture actively toxic Pfiesteria. In this article, we describe the standardized steps of our fish bioassay as an abbreviated term for a procedure that includes two sets of trials with fish, following the Henle-Koch postulates modified for toxic rather than infectious agents. This procedure was developed in 1991, and has been refined over more than 12 years of experience in …

Determination Of Life Cycle Cost Under Uncertainty, Hamoud R. Al-Otaibi

Mechanical & Aerospace Engineering Theses & Dissertations

The subject of this thesis is a Life Cycle Cost (LCC) model that takes into consideration the uncertainty of equipment failure rate and input data. The outcome of LCC depends on numerous estimates, forecasts, assumptions, and approximations of real-life data. Each of these factors has the potential to introduce error into the results. The study focuses upon the database generated for equipment failure rates data developed from historical database based on Weibull distribution parameters. The model provides a method to simulate real-world project life cycle.

Computational Fluid Dynamic Study Of A Nascar Winston Cup Series Race Car, Terry L. Meek Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Since the goal of NASCAR racing is to win and since drag is a force the vehicle must overcome, a thorough understanding of the drag generating airflow around and through the automobile is greatly desired. The external airflow contributes to most of the drag that a car experiences and most of the downforce the vehicle produces. Therefore, an estimate of the vehicle's performance may be evaluated using a computational aerodynamics model. This thesis presents a computational fluid dynamic (CFD) analysis of a NASCAR Winston Cup series race car to investigate the salient flow characteristics.

Before a computational analysis could be …

An Object-Oriented Resource Pool Model In Support Of Discrete Event Simulations, Srinivas Gullapalli

Electrical & Computer Engineering Theses & Dissertations

The proper distribution of resources is a key factor in simulation. Resources provide the supporting facilities, equipment, and personnel for carrying out activities. The number of resources has a direct impact on the overall effectiveness of the simulation as it does in real life. If the number is insufficient, it generally takes more time for the process to complete. On the other hand, if the number is too high, the cost incurred on the resources will be unnecessarily large. Therefore, the count should be a compromise between the two extremes.

In this thesis, an attempt is made to generalize the …

The Distribution Of Airborne Coal Dust In Soil Profiles Of Norfolk, Va And Its Implication For Arsenic Loading To These Soils, William Joseph Bounds

OES Theses and Dissertations

Norfolk, Virginia is home to the Northern Hemisphere's largest coal terminal the Lamberts Point Docks. The coal loading process of this terminal creates large amounts of coal dust, which subsequently is distributed throughout the local region by atmospheric transport and deposition. While the coal dust itself poses only minor health hazards, certain trace elements within the coal, particularly arsenic, may pose environmental as well as significant health hazards. Within coal, arsenic occurs primarily in the mineral pyrite. As pyrite in the coal dust is subsequently oxidized via exposure to the atmosphere and/or meteoric water, arsenic may be released to the …

Investigation Of Dual-Mode Combustion With Large Upstream Interaction, Melanic Olynciw-Mills

Mechanical & Aerospace Engineering Theses & Dissertations

Dual-mode scramjet combustor configuration with significant upstream interaction is investigated numerically. The possibility of scaling the domain to accelerate the convergence an3 reduce the computational time is explored. The supersonic combustor configuration was selected to provide an understanding of key features of upstream interaction and to identify physical and numerical issues relating to modeling of dual-mode configurations. The numerical analysis was performed with vitiated air at freestream Mach number of 2.5 using hydrogen as the sonic injectant. Results are presented for two-dimensional models and a three-dimensional jet-to-jet symmetric geometry. Comparisons are made with experimental results. Two-dimensional and three-dimensional results show …

Transonic And Supersonic High Alpha Flow Prediction And Control For An Sc-X Space Vehicle, Ruobo You

Mechanical & Aerospace Engineering Theses & Dissertations

Universal Space Line (USL) is interested in developing an aerospace vehicle that flies at very high angles of attack (AOAs) through wide range of Mach numbers. The basic model configuration is called SC-X model, which consists of a blunt cone and a cylindrical afterbody. A structured O-type grid was generated for this model by numerically solving elliptic partial differential equations. The three-dimensional, unsteady, compressible, Reynolds-averaged Navier-Stokes equations coupled with Spalart-Allmaras turbulence model were used as computational tool to investigate the transonic and supersonic flows around the SC-X model pitched at AOA of 45°. For the code validation, this computational solver …

Longitudinal Analysis Of Cohesion In Student Work Teams: The Efficacy Of Teamwork Skills Training, Kari Rachel Strobel

Psychology Theses & Dissertations

This study was a longitudinal examination of the effects of teamwork skills training on team cohesion and team performance. Participants were 11 teams, made up of three-to-five undergraduate students who enrolled in a team-based Industrial/Organizational psychology course. For 16 weeks, each team completed three graded assignments per week and was tracked with regard to levels of task and social cohesion. During the seventh week, teams received theory-based training on basic teamwork processes. Results indicate that the training intervention had a significant positive impact on team cohesion. However, training did not affect team performance levels as expected. Discussion centered on the …

Changing Roles Of Title I Reading Teachers In Light Of New Provisions And Teamteaching Model, Abha Gupta, Eileen S. Oboler

Teaching & Learning Faculty Publications

We present the important and very complicated roles of the Title I Reading teacher in light of a new instructional paradigm: teamteaching. Following the 1994 reauthorization of Title I, Reading teachers often find themselves in multiple professional roles (Improving America's Schools Act, 1994). Based on observational data collected in our research on elementary school communities, five major categories of professional roles emerged (Oboler, 1993; Gupta and Oboler, 1998). We interpret Reading teachers' roles with respect to the new provisions found in the Interim Report, 1996, issued by the U.S. Department of Education (http://www.ed.gov/pubs/NatAssess), and Title I, Part A, Title I …

Circulation, Vol. 8, No. 2, Center For Coastal Physical Oceanography, Old Dominion University, Larry P. Atkinson

CCPO Circulation

Summer 2001 issue of CCPO Circulation featuring article "Oceanographic Research in the Antarctic" by Larry Atkinson

Abstracts Of Papers, 79th Annual Meeting Of The Virginia Academy Of Science, May 22-25, 2001, James Madison University, Harrisonburg, Virginia

Virginia Journal of Science

Abstracts of papers that were presented at the 79th Annual Meeting of the Virginia Academy of Science, May 22-25, 2001, James Madison University, Harrisonburg, Virginia.

Virginia Junior Academy Of Science 2001 Award Winners, Virginia Journal Of Science

Virginia Journal of Science

Virginia Junior Academy of Science 2001 Award Winners, presented at James Madison University, Harrisonburg, VA, on May 23, 2001.

Benthic Biological Monitoring Program Of The Elizabeth River Watershed (2000), Daniel M. Dauer

Elizabeth River Reports

Executive Summary

A study of the macrobenthic communities of the Elizabeth River watershed was initiated in summer 1999. This report presents the data from the second year of sampling in 2000. The three objectives of the Benthic Biological Monitoring Program of the Elizabeth River watershed are: (1) To characterize the health of the tidal waters of the Elizabeth River watershed as indicated by the structure of the benthic communities. ( 2) To conduct trend analyses on long-term data at 14 fixed-point stations to relate temporal trends in the benthic communities to changes in water and/or sediment quality. Trend analyses will …

Measurement Of The Gπnn(T) Form Factor, Kelly Gene Vansyoc

Physics Theses & Dissertations

Cross sections were measured for the reaction ¹H(e, e′π+) n at the energy W = 1.95 GeV and momentum transfer Q² = 0.6 (GeV/c)². At this W and Q², the longitudinal cross section is dominated by t-channel production, giving a unique opportunity to examine the strong coupling form factor gπNN(t). The measured cross sections were separated using a method similar to a Rosenbluth separation. For the extraction of gπNN(t), the Actor and Körner model [42] and a parameterization of the MAID2000 …

Dynamical Sedimentary Models Of Shallow Marine Environments, Yong Zhang

OES Theses and Dissertations

This treatise represents a contribution of quantitative, dynamical sedimentary modeling to the analytical understanding of sedimentary processes in shallow marine environments. The dynamical sedimentary models in this treatise numerically simulate the sedimentary processes from an event time scale, based on the fundamental physics of sediment dynamics in coastal and shelf depositional environments, to a longer, facies time scale. The simulated geologic processes serve to the illustrate shoreface equilibrium profile, shelf storm bed generation, and the shelf sedimentary facies system.

This treatise presents a nearshore profile evolution model for the abandoned Huanghe Delta, a two-dimensional storm deposition model, and a sedimentary …

Simulation Optimization Studies Of Routing And Process Flow Problems, Satish Ravichandran

Electrical & Computer Engineering Theses & Dissertations

Computer aided simulation is emerging as a powerful tool for numerical analysis and in conducting performance evaluations of complex systems that depend on a multitude of variables. The primary objective in such simulation studies is to gauge the performance of the system under a various constraints and operating conditions. The effects of changing the operating parameter space can thus be analyzed without having to implement costly changes. Simulations are also carried out for the baseline scenarios to verity and validate the basic underlying system model. In this thesis research, two practical problems were studied through numerical modeling, and optimized solutions …

A Scanning Electron Microscopy Comparison Of The Effects Of The Arkansas Stone And The Ida-Hone Ceramic Stone On Curet Sharpness And Root Smoothness, Marian Gayle Rubino

Dental Hygiene Theses & Dissertations

Purpose: The purpose of this study was to determine if there are statistically significant differences between the Arkansas sharpening stone and the Ida-Hone ceramic sharpening stone in producing a sharper cutting edge on dental curets, and to determine if there is a statistically significant difference between the degree of root smoothness achieved by the sharpened curet cutting edges on extracted human teeth.

Methods: A two-group, randomized subject (n=39), double blind, post-test only design was employed using 39 factory new Hu-Friedy 11/12 gracey curets. Curets in group one were sharpened using the Ida-Hone ceramic stone, curets in group two were sharpened …

The Effects Of Occupational Ultrasonic Noise Exposure On Hearing In Dental Hygienists: A Pilot Study, Jennifer S. Dunning

Dental Hygiene Theses & Dissertations

The purpose of this case-control study was to determine whether long-term ultrasonic noise exposure via the dental office environment is related to dental hygienists' hearing status. Registered dental hygienists (N = 698) who live in the Hampton Roads area were mailed a Dental Hygiene Work History Questionnaireto determine those meeting the inclusion criteria and willing to participate in the study. Consenting subjects were categorized into one of two groups according to ultrasonic scaler usage rate and matched on age. Persons with known hearing loss due to infection, disease, or congenital defect were excluded from the study. The final sample …

Trichodesmium Spp.: Numerical Studies Of Resource Competition, Carbohydrate Ballasting, And Remote-Sensing Reflectance, Tonya Denise Clayton

OES Theses and Dissertations

In recent years, a new appreciation for the role of diazotrophy in the oceans has emerged. This dissertation reports on three modeling studies designed to investigate ecological processes associated with Trichodesmium spp., the most conspicuous marine diazotroph: (1) characterization of a generalized model Trichodesmium and issues of macronutrient resource competition; (2) carbohydrate ballasting by Trchodesmium and implications for the formation of surface accumulations; and (3) the vertical distribution of Trichodesmium and implications for detection from space.

The first study focuses on issues of nitrogen and phosphorus competition and ecosystem structure. It utilizes a simple ecosystem model that includes dissolved nitrogen …

Hydrographic Variability On Decadal And Interdecadal Scales In The Northern Gulf Of Alaska, Nandita Sarkar

OES Theses and Dissertations

The mixed layer depth (MLD) in the North Pacific is important to vertical mixing and hence the flux nutrients into the euphotic zone. A time series of hydrographic measurements, tem perature and salinity versus depth, at a coastal site in the northern Gulf of Alaska is used to determine the seasonal and interannual variations in the MLD. Data from this station called GAK 1 (59°50.7‘X. 149C28.0'\V) in 203 m of water begin in 1974 and end in 1998. The MLD changes seasonally from about 50 m in summer to more than 130 m in winter. These changes are in response …

Transverse Variability Of The Flow And Density In Inlets Of Southern Chile, Mario Arturo Cáceres Muñoz

OES Theses and Dissertations

Measurements of velocity and density profiles were made to describe the flow transverse structure in three inlets of southern Chile. The inlets show marked differences in their transverse dynamics in response to external forcing. In Aysen Fjord (45.2°S) the mean flow showed a three layer structure that was consistent with up-fjord wind-induced exchange, while in Chacao Channel (41.8°S), the mean flow exhibited predominantly a lateral structure that featured sharp velocity shears. In both cases, a bank in the center of the sections seemed to play an important role in shaping the mean flows. In Ventisquero Sound (44.4°S), the presence of …

Development Of Atlas Based Simulation Capability For Automated Testing, Rami Hanbali

Electrical & Computer Engineering Theses & Dissertations

Computer software is emerging as a powerful tool for controlling a large number of instruments and for the testing of these instruments. The main aim of this work is to provide a software program capable of controlling a large number of engineering instruments at the touch of a button. In addition, the software is to have the capability of connecting the instruments with the desired Unit Under Test. There is great need for such software driven testing in industry, especially for large complex systems. Advantages of such an approach include: (a) automated testing in a very quick and efficient manner; …

Optimal Aeroelastic Vehicle Sensor Placement For Root Migration Flight Control Applications, Abdul Ghafoor Al-Shenhabi

Mechanical & Aerospace Engineering Theses & Dissertations

An important step in control design for elastic systems is the determination of the number and location of control system components, namely sensors. The number and placement of sensors can be critical to the robust functioning of active control systems, especially when the system of interest is a large high-speed aeroelastic vehicle. The position of the sensors affects not only system stability, but also the performance of the closed-loop system. In this dissertation, a new approach for sensor placement in the integrated rigid and vibrational control of flexible aircraft structures is developed. Traditional rigid-body augmentation objectives are addressed indirectly through …

Pulsed Electron Heating Of Atmospheric Pressure Air Glow Discharges, Hisham Merhi

Electrical & Computer Engineering Theses & Dissertations

By applying electric field pulses of short duration (compared to the time constant for glow-to-arc transitions) to a weakly ionized gas, the electron energy distribution can be temporarily shifted to higher energies. This effect causes a nonlinear increase in the ionization rate and consequently a larger electron decay time. This effect has been demonstrated using single pulse operation.³ In order to generate plasma with semi-continuous electron density, repetitive operation is required. As a first step towards repetitive pulsed electric field operation, the temporal development of the voltage across the plasma for two subsequent pulses was measured. The dual pulse …

Minimum Mean Square Error Spectral Peak Envelope Estimation For Automatic Vowel Classification, Jaishree Venugopal

Electrical & Computer Engineering Theses & Dissertations

Spectral feature computations continue to be a very difficult problem for accurate machine recognition of speech. In this work, which focuses on vowels, a new spectral peak envelope method for vowel classification is developed, based on a missing frequency components model of speech recognition. According to the missing frequency components model, vowel recognition depends only on the spectral (harmonic) peaks. Smoothing and interpolation of the spectra, performed in the standard cepstral analysis method commonly used in automatic speech recognition, actually loses valuable information and results in reduced recognition accuracy. The new method for feature extraction presented in this thesis is …

Sulphur By-Product: A Potential Indicator Of Early Dental Plaque-Induced Gingival Disease Activity: A Pilot Study, Hui Zhou

Dental Hygiene Theses & Dissertations

The purpose of this study was to determine the relationship between volatile sulfide compounds and gingival health status, and to identify if volatile sulfide compounds can detect early dental plaque-induced gingival disease, using an experimental gingivitis model. The sample consisted of 12 subjects between 19 and 28 years, with a healthy gingival status. A split-mouth design utilizing only the mandibular arch was used. A baseline full-mouth periodontal probing status was measured. After baseline data collection and for two weeks, subjects refrained from brushing and flossing one randomly selected half of the mandibular arch. At baseline and six subsequent appointments, gingival …

Circulation, Vol. 8, No. 1, Center For Coastal Physical Oceanography, Old Dominion University, Ann E. Gargett

CCPO Circulation

Spring 2001 issue of CCPO Circulation featuring article "Remarks from a New Arrival: Dr. Ann Gargett"