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Adaptive Control Of Large Amplitude Nonlinear Free Vibrations Of Composite Shallow Shells Using System Identification And Self-Sensing Piezoelectric Actuators, Minseock Park

Mechanical & Aerospace Engineering Theses & Dissertations

A coupled structural-electrical nonlinear modal finite element formulation for anti-symmetrical laminated composite shallow shells with embedded piezoelectric sensors and actuators is presented for the suppression of large-amplitude nonlinear free vibrations. The triangular shallow shell finite element is utilized, which is developed &om an extension of the triangular Mindlin (MIN3) element with the improved shear correction factor. The system equations of motion are first derived in the physical structural-node degrees of freedom (DOF), However, numerical simulation in structural-node DOF is costly in computation due to the large size of system matrices, and the nonlinear terms have to be updated at each …

Stochastic Calculations For Computation Of Radiation Effects And Cell Survivability Under Voltage Pulsing, Madhuri Ganapathiraju

Electrical & Computer Engineering Theses & Dissertations

Statistical computations are an important tool for the analysis of stochastic phenomena and processes that are characterized by variability. Biological systems (e.g., cells, tissues etc.) are perfect examples wherein response to a given external stimulus can be varied and needs to be adequately considered. The Monte Carlo method of analysis has now been recognized as the most effective way of treating stochastic variability.

This thesis uses Monte Carlo based simulations to probe two problems that require the quantification and modeling of effects caused by energy deposition onto biological matter from external sources. One problem involves the probabilistic study of the …

Uncertainty Assessment Of Aircraft Maintenance Times By Using Evidence Theory And Expert Judgment Elicitation, Huseyin Kudak

Engineering Management & Systems Engineering Theses & Dissertations

The goal of this study is to demonstrate the use of the Dempster-Shafer Theory of evidence as a decision aid to predict aircraft maintenance times during wartime operations using expert judgment elicitation. Increased precision in time estimation enables the jet engine aircraft maintenance facility commander to make more accurate decisions for the Air Force's wartime tactical operations allowing the commander to gain a decisive advantage. A questionnaire was designed to elicit judgments from experts in the Aircraft Maintenance Facility (AMF) to investigate maintenance times of the major failure modes (Ignition, Fuel, and Electrical). Results of the expert judgment elicitation were …

Analysis And Application Of Perfectly Matched Layer Absorbing Boundary Conditions For Computational Aeroacoustics, Sarah Anne Parrish

Mathematics & Statistics Theses & Dissertations

The Perfectly Matched Layer (PML) was originally proposed by Berenger as an absorbing boundary condition for Maxwell's equations in 1994 and is still used extensively in the field of electromagnetics. The idea was extended to Computational Aeroacoustics in 1996, when Hu applied the method to Euler's equations. Since that time much of the work done on PML in the field of acoustics has been specific to the case where mean flow is perpendicular to a boundary, with an emphasis on Cartesian coordinates. The goal of this work is to further extend the PML methodology in a two-fold manner: First, to …

Parallel Mpi/Fortran Finite Element Symmetrical/Unsymmetrical Domain Decomposition, Siroj Tungkatara

Civil & Environmental Engineering Theses & Dissertations

MPI/FORTRAN finite element analysis software based on Domain Decomposition (DD) formulas has been developed in this work. Efficient input data storage/data communication schemes, domain partitioning, fast symbolical and numerical sparse assembly, symmetrical/unsymmetrical sparse solver and robust symmetrical/unsymmetrical iterative solvers algorithms are all incorporated into the developed code. Parallel Precondition Conjugated Gradient (PCG) and Flexible Generalized Minimum Residual (FGMRES) are developed. Efficient computational techniques used in the developed code are explained. Numerical performance and the accuracy of the developed code are conducted on acoustic examples with medium to large grid sizes. The results obtained from ODU Wilbur cluster (under parallel processing …

Validation Of A New Method Of Estimating Vo2max Based On Vo2Reserve With Treadmill Exercise, Julie Lynn Ward

Human Movement Studies & Special Education Theses & Dissertations

The purpose of the current study was to establish and then validate a treadmill protocol to predict VO_2max based on VO₂Reserve.

Methods

A treadmill protocol was developed to elicit approximately 60-70% of heart rate reserve (HRR) in the fifth and sixth minutes of the final stage. The protocol involved walking on a treadmill at 3.0 mph, with grade increasing by 1 % each minute until 50% HRR was reached. Then, an additional 5 minutes of walking at the final grade was performed. A study population of 60 volunteers (30 male; 30 female), considered low risk by ACSM …

Disassembly Planning And Costing Through Petri Net Approach, Chunhsi Lei

Mechanical & Aerospace Engineering Theses & Dissertations

In the current consumer oriented environment, many new products appear in the market almost on a daily basis. Lured by advertisements and tempted by new product features, customers are constantly purchasing newer products. Acquiring newer products for often leads to throwing out older ones, but it is a totally different story for manufacturers. They need to consider the best way to reuse a product both for economic purposes and for environmental protection. Considerations for them often include: how to minimize total disassembly cost, how to achieve the lowest total disassembly time at each processing step, and how to sort valuable …

Real-Time Ultrasound Simulation For Medical Training And Standardized Patient Assessment, Bo Sun

Computational Modeling & Simulation Engineering Theses & Dissertations

With the increasing role played by ultrasound in clinical diagnostics, ultrasound training in medical education has become more and more important. The clinical routine for ultrasound training is on real patients; therefore monitored and guided examinations involving medical students are quite time-constrained. Furthermore, standardized patients (SPs), who are increasingly used in medical school for teaching and assessing medical students, need to be augmented. These SPs are typically healthy individuals who can not accurately portray the variety of abnormalities that are needed for training especially when medical examinations involve instrument interactions. To augment SPs in a realistically effective way and also …

Circulation, Vol. 15, No. 1, Center For Coastal Physical Oceanography, Old Dominion University, Tal Ezer

CCPO Circulation

Spring 2008 issue of CCPO Circulation featuring article "Hydrodynamic Numerical Ocean Models Support Environmental Studies and Conservation Efforts: From an Arctic Estuary to a Caribbean Coral Reef" by Dr. Tal Ezer

Hydrodynamic Numerical Ocean Models Support Environmental Studies And Conservation Efforts: From An Arctic Estuary To A Caribbean Coral Reef, Tal Ezer

CCPO Publications

Potential future climate changes, as highlighted recently by the Intergovernmental Panel on Climate Change (IPCC) report, are likely to have different local impacts in different regions of the globe. Oceanic ecosystems may be especially sensitive to large environmental variation, and they are closely connected to physical changes such as temperature, salinity, currents and sea level. Two examples, from very different environments – one in a cold climate and one in a tropical climate, will be discussed here to show how hydrodynamic numerical models are helping to understand physical-biological interactions and potentially help dealing with future climate changes.

Numerical Simulations Of A Nonlinear Transmission Line, Stuart Rogers

Electrical & Computer Engineering Theses & Dissertations

This thesis investigates wave propagation along a nonlinear transmission line having a voltage-dependent capacitance. The telegrapher's equations that model wave propagation along such a transmission line are derived and shown to represent a nonlinear hyperbolic system of balance laws. The Lax-Friedrichs, Lax-Wendroff, and hybrid numerical schemes for obtaining approximate solutions to nonlinear hyperbolic systems of balance laws are presented, analyzed, and applied to the nonlinear telegrapher's equations. The Lax-Wendroff and hybrid schemes are invoked to numerically simulate wave propagation along a nonlinear transmission line. Simulations obtained via the hybrid scheme are used to briefly study the potential application of a …

The Effect Of Hans Device On Brain Pressure Values In Finite Element Brain Models, Mihir M. Jawale

Mechanical & Aerospace Engineering Theses & Dissertations

A parametric study of behavior of different brain material properties when exposed to a mid-high severity pulse is presented. Few studies have considered brain pressure as a parameter to study the effect of change of brain material properties. Specifically pressure and strain values in the frontal and posterior fossa and occipital region of the brain are investigated for mid-high severity pulse.

The brain model is composed of several parts modeled as hexahedral elements and with different material properties. A parametric study of several material types of brain is conducted using MAthematical DYnamic MOdel (MADYMO). Initially only the finite element (FE) …

In Vitro Comparison Of 360° Unirotational Disposable Prophylaxis Angles Versus 90° Reciprocating Disposable Prophylaxis Angles On Spatter During Rubber Cup Polishing, Kelly Marie Schulz

Dental Hygiene Theses & Dissertations

The purpose of this in vitro study was to compare the traditional 360° unirotational disposable prophylaxis angle (DPA) to a 90° reciprocating DPA in terms of spatter production. The 2x3x3 factorial design involved: 2 types of DP As x 3 types of prophylaxis pastes (fine, medium and coarse) x 3 dental handpiece revolutions per minute (rpm) settings (1500, 2000, and 3000). The eStylus'™ operated the DP As under controlled speeds. Using a mounted dental manikin, 90° reciprocating DP As and 360° unirotational DP As were evaluated for spatter production with the use of prophylaxis pastes of various grits in 270 …

A Weighted Modular Principal Component Analysis Approach For Face Authentication, Chandrika Tummala

Electrical & Computer Engineering Theses & Dissertations

A weighted modular approach for face authentication based on the priorities of different facial regions that change with varying poses, expressions and occlusions is presented in this thesis. This helps in verifying the identity of an individual who claims to be a subject in the database and is unaware of the presence of the face authentication system. A sequence of face images is selected from a video in a particular predefined interval and is used for verification. The face images are divided into different horizontal modules based on the regions representing facial features. A principal component analysis on these modules …

Virginia Standards Of Learning: An Analysis Of Sociodemographic Effects On Exam Passing Rates, Anne E. Foster

Sociology & Criminal Justice Theses & Dissertations

This study proposed to analyze the effects that sociodemographic variables have on Virginia Standards of Learning (SOL) exam passing rates. By analyzing Census data along with passing rates from the Virginia Department of Education, the researcher determined if the independent variables white, non-white, poverty, female-headed household and foreign born explained variance in the SOL passing rates. By using linear regressions for each independent variable as well as a regression for a combination of the independent variables, the researcher was able to show the amount of variance that was explained. The results confirm that variance was present in each test subject …

Modeling The Seasonal Sea Ice Cycle In The Ross Sea, Antarctica, Yusuf Sinan Hûsrevoğlu

OES Theses and Dissertations

A mesoscale resolution (5 km) regional ocean model (ROMS), coupled thermodynamically/dynamically to a sea ice model (CICE) and thermodynamically to an ice shelf is used to investigate Ross Sea seasonal sea ice cycle, polynya dynamics, distribution and transformations of continental shelf water masses, and bottom water formation. Daily atmospheric forcing is from the ECMWF ERA-40 dataset, and for a separate simulation, wind forcing for Terra Nova Bay is substituted from daily automatic weather station (AWS) data. Simulated Ross Sea sea ice concentration reproduces the winter lead opening events observed in the SSM/I signal; however, it underestimates open water area (rmsd …

The Relationship Of Teacher Route To Certification To Student Outcomes On Statewide Social Studies Assessment, Aaron L. Smith

Educational Leadership & Workforce Development Theses & Dissertations

Public school divisions face daunting challenges today. One such challenge is the ability to recruit and retain highly qualified and effective teachers. Endemic teacher shortages coupled with escalating national education standards make it imperative that school divisions hire and retain teachers who can positively and immediately impact student achievement. Schools without effective teachers face possible sanctions, which could include re-staffing of the school, parental choice that would allow the student population to attend more successful schools and loss of funds.

At the same time, colleges and universities have begun alternative certification programs in an effort to compensate for teacher shortages …

A Program Evaluation Of Supplemental Instruction For Developmental Mathematics At A Community College In Virginia, Marilyn Lawson Peacock

Educational Leadership & Workforce Development Theses & Dissertations

With the current emphasis on accountability and the importance of math skills in our present economy, the success of developmental mathematics students at community colleges is critical. How to improve the success of these developmental students has become the impetus for many educational initiatives. One educational innovation in tutoring, called supplemental instruction, has been successfully applied to high-risk courses which are defined to have a failure rate in excess of 30%. Mid-Atlantic Community College, in its Title III grant which seeks to improve the success of developmental students, selected supplemental instruction as its initiative. This program evaluation investigated the effects …

Photoassociative Spectroscopy Of Ultracold Metastable Argon And Study Of Dual Species Trap Loss In A Rubidium-Metastable Argon Mot, Michael K. Shaffer

Physics Theses & Dissertations

This dissertation presents the findings of two experimental investigations in ultracold atomic and molecular physics: The study of the dual species trap loss in a rubidium - metastable argon magneto-optical trap and the photoassociative spectroscopy of ultracold metastable argon. The interspecies trap loss rate coefficients have been measured for ultracold collisions between ⁸⁵Rb and ⁴⁰Ar* in a dual-species magneto-optical trap (MOT) and the two rates have been found to be approximately equal over the range of intensities studied with values of β'_Rb–Ar* = 3.0 ± 1.3 × 10^-11 cm³/s and β'_Ar*–Rb = 1.9 …

Developing A Repeatable And Reliable Methodology To Determine Return-On-Investment, Mark Cullen Nesselrode

Computational Modeling & Simulation Engineering Theses & Dissertations

The high costs of modern weapons systems, fuel, personnel, and increasing environmental awareness is forcing U.S. forces to rely on simulation for training. Further, the need to train in a robust and theater specific environment is critical to ensure operational readiness immediately upon reaching the combat theater. Finally, the rapidly changing nature of the conflicts, crises, or contingencies in which U.S. forces are involved requires a new approach to training.

The purpose of this research is to develop and demonstrate the feasibility of a methodology that can provide a reliable, consistent method for determining ROI in various forms, focusing on …

Frontal Variability In Drake Passage - A Modeling Study, Bin Zhang

OES Theses and Dissertations

The Antarctic Circumpolar Current (ACC) features three major fronts: the Sub-antarctic Front (SAF), the Polar Front (PF), the Southern ACC Front (SACCF). The locations of these fronts are not stable. The PF can shift away from its historical mean locations on the order of 100 km. The ACC transport in Drake Passage varies over a large range (50 to 60 Sv). Numerical simulations with the Regional Ocean Modeling System are carried out to study the frontal variability under the influence of ACC transport, local wind stress and bottom topography in Drake Passage.

Front-embedded numerical experiments are carried out without surface …

Study Of Multibody Dynamics Using Matlab, Kalyani Soman

Mechanical & Aerospace Engineering Theses & Dissertations

Research in computational dynamics has gained importance in the past few years because of the demand for analysis and simulation of various multi-body systems in the growing mechanical and aerospace industry. These multi-body systems are made of individual bodies that are interconnected via mechanical joints. Mathematically, these joints that connect the bodies can be described as constraint equations imposed upon the motions of the involved free bodies. This process will result in an equation of motion expressed in the form of a differential-algebraic equation. It is the main objective of this thesis to develop a solution algorithm that can take …

Community-Of-Interest (Coi) Model-Based Languages Enabling Composable Net-Centric Services, Andreas Tolk, Saikou Y. Diallo

Computational Modeling & Simulation Engineering Faculty Publications

Net-centric services shall be designed to collaborate with other services used within the supported Community of Interest (COI). This requires that such services not only be integratable on the technical level and interoperable on the implementation level, but also that they are composable in the sense that they are semantically and pragmatically consistent and able to exchange information in a consistent and unambiguous way.

In order to support Command-and-Control with Composable Net-centric Services, the human-machine interoperation must be supported as well as the machine-machine interoperation. This paper shows that techniques of computer linguistic can support the human-machine interface by structuring …

Dedication To Pierre Lallemand On The Occasion Of His Retirement, Dominque D'Humieres, Manfred Krafczyk, Li-Shi Luo, Robert Rubinstein

Mathematics & Statistics Faculty Publications

The fourth international conference for mesoscopic methods in engineering and science (http://www.icmmes. org), held in Munich, Germany, 16–20 July 2007, was closed with a celebration honouring Dr Pierre Lallemand on the occasion of his retirement from the Centre National de la Recherche Scientifique (CNRS) after more than 40 years of service.

Exploring Interdisciplinary Prayer Research In A Health Context, E. James Baesler

Communication & Theatre Arts Faculty Publications

Communication, Psychology, and Sociology are three leading academic disciplines engaged in the social scientific study of prayer, the spiritual communication between a believer(s) and God, but rarely do these disciplines collaborate in interdisciplinary prayer scholarship. Possibilities for interdisciplinary prayer research in a health context are explored through a review of the literature and academic interviews. Interdisciplinary linkages in the prayer-health context are organized in an integral "all-quadrant" theoretical model, and an assessment of the viability of interdisciplinary prayer-health research is considered.

Professor Gopal Kanji's Retirement As Editor Of Journal Of Applied Statistics, M. C. Agrawal, Steven B. Caudill, S. Chakraborti, Norman Draper, Ian Dryden, Joe Gani, Steven G. Gilmour, Z. Govindarajulu, David J. Hand, Dayanand Naik

Mathematics & Statistics Faculty Publications

(First paragraph) This. issue of Journal of Applied Statistics marks the first in its history which does not fall under the editorship of its founder Professor Gopal Kanji. Following his retirement from the role we would like to use this editorial to outline the history and development of the Journal and pay tribute to the many achievements of Gopal’s career.

A Comparison Of Different Methods For Predicting Cancer Mortality Counts At The State Level, Corinne Wilson

Virginia Journal of Science

Cancer is a major health issue in the United States. Reliable estimates of yearly cancer mortality counts are essential for resourcing and planning. The American Cancer Society has used several methods of forecasting to estimate the future cancer burden and researchers are continually working to develop new methods with improved performance. There have been studies comparing different models for predicting the US cancer mortality counts. This study explores and compares several different models for cancer mortality count predictions at the state level, principally for the state of Virginia. Results of the comparisons appear to show the final improved model to …

Studies Of Breakdown In A Pressurized Rf Cavity, M. Bastaninejad, A. A. Elmustafa, C. M. Ankenbrandt, A. Moretti, M. Popovic, K. Yonehara, D. M. Kaplan, M. Alsharo'a, P. M. Hanlet, R. P. Johnson, M. Kuchnir, D. Newsham, D. V. Rose, C. Thoma, D. R. Welch

Mechanical & Aerospace Engineering Faculty Publications

Microscopic images of the surfaces of metallic electrodes used in high-pressure gas-filled 805 MHz RF cavity experiments [1] have been used to investigate the mechanism of RF breakdown [2]. The images show evidence for melting and boiling in small regions of ∼10 micron diameter on tungsten, molybdenum, and beryllium electrode surfaces. In these experiments, the dense hydrogen gas in the cavity prevents electrons or ions from being accelerated to high enough energy to participate in the breakdown process so that the only important variables are the fields and the metallic surfaces. The distributions of breakdown remnants on the electrode surfaces …

Naturally Present Fatty Acids As Internal Calibrants For Fourier Transform Mass Spectra Of Dissolved Organic Matter, Rachel L. Sleighter, Georgina A. Mckee, Zhanfei Liu, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The analysis of dissolved organic matter ( DOM) by Fourier transform ion cyclotron resonance mass spectrometry ( FTICR- MS) has gained wide interest recently, driven primarily by its ultrahigh resolving power and mass accuracy. Accurate calibration of mass spectra is a key step to successfully decipher the DOM components. We propose a simple and accurate method to internally calibrate the peaks in the complex spectra without the need to add a calibrant. Mass spectra of DOM samples from the Dismal Swamp, Virginia, and the lower Chesapeake Bay display the presence of naturally occurring fatty acids which can be readily recognized …

Determination Of Photochemically Produced Carbon Dioxide In Seawater, Emily M. White, David J. Kieber, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

An analytical system was developed to determine photochemically produced carbon dioxide in marine waters. Our system was designed to measure low levels of carbon dioxide by maintaining a closed system to prevent atmospheric contamination during sample preparation, irradiation, and analysis. To detect low levels of photoproduced carbon dioxide in seawater, background dissolved inorganic carbon (DIC) was removed before irradiation. To strip out DIC, samples were acidified to pH 3.0 (converting DIC to carbon dioxide) and bubbled with low carbon dioxide air. The pH was then readjusted back to the original value, and the resulting low-DIC seawater samples were transferred pneumatically …