Physical Sciences and Mathematics Commons^™

Chemical Modification Of Cvd Diamond Electrodes, Robert Matthew Johnson

Chemistry & Biochemistry Theses & Dissertations

The micro-array behavior of boron doped CVD diamond thin film electrodes has been studied in acetonitrile containing two redox couples. The analytical technique employed in these studies was cyclic voltammetry. One system is 0.4 mM ferrocene containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAH). This reversible redox system is not only well-known, but also involves only one electron transfer with no breakage/formation of chemical bonds, thus making it a simple system for analysis. The second test is 0.8 mM cobaltocenium hexafluorophosphate, with 0.4 mM ferrocene as an internal standard. Unlike ferrocene, which is neutral initially, cobaltocenium is positively charged, and is reduced …

Architectural Optimization Of Digital Libraries, Aileen O. Biser

Computer Science Theses & Dissertations

This work investigates performance and scaling issues relevant to large scale distributed digital libraries. Presently, performance and scaling studies focus on specific implementations of production or prototype digital libraries. Although useful information is gained to aid these designers and other researchers with insights to performance and scaling issues, the broader issues relevant to very large scale distributed libraries are not addressed. Specifically, no current studies look at the extreme or worst case possibilities in digital library implementations. A survey of digital library research issues is presented. Scaling and performance issues are mentioned frequently in the digital library literature but are …

Determination Of The N-Terminal Amino Acid Residues On Polypeptides In Secondary Wastewaters, Edward L. Creecy

Chemistry & Biochemistry Theses & Dissertations

The N-terminal amino acid residues on polypeptides and proteins were determined in wastewaters prior to chlorination. The terminal amino groups'ere first derivatized with the well known derivatizing agent dansyl chloride, and then the resulting dansyl amino acid hydrolyzed from the peptide chain by a propionic acid/ hydrochloric acid mixture. The resulting dansyl amino acids were then separated and detected using reversed phase high performance liquid chromatography with fluorescence detection. The majority of N-terminal residues detected were the more polar amino acids. Concentrations ranged from 1 x 10^-10 to 3 x 10^-7 moles/liter. It is suggested that the shorter …

Superconvergence In Iterated Solutions Of Integral Equations, Peter A. Padilla

Mathematics & Statistics Theses & Dissertations

In this thesis, we investigate the superconvergence phenomenon of the iterated numerical solutions for the Fredholm integral equations of the second kind as well as a class of nonliner Hammerstein equations. The term superconvergence was first described in the early 70s in connection with the solution of two-point boundary value problems and other related partial differential equations. Superconvergence in this context was understood to mean that the order of convergence of the numerical solutions arising from the Galerkin as well as the collocation method is higher at the knots than we might expect from the numerical solutions that are obtained …

Multiple Streams Synchronization In Collaborative Multimedia Systems, Emilia Stoica

Computer Science Theses & Dissertations

With the recent increase of the communication bandwidth and processor power, new types of applications have emerged. Among them, there are multimedia application, in which users are able to control, combine, and manipulate different types of media, such as text, sound, video, computer graphics, and animation. A key requirement in any multimedia application is to synchronize the delivery of various media streams to the user. To achieve this, the sender has to provide the temporal relations between the streams as they are captured. Since the receiver uses this information in streams presentation, its accuracy is very important.

Our main contribution …

The Solution Of Hypersingular Integral Equations With Applications In Acoustics And Fracture Mechanics, Richard S. St. John

Mathematics & Statistics Theses & Dissertations

The numerical solution of two classes of hypersingular integral equations is addressed. Both classes are integral equations of the first kind, and are hypersingular due to a kernel containing a Hadamard singularity. The convergence of a Galerkin method and a collocation method is discussed and computationally efficient algorithms are developed for each class of hypersingular integral equation.

Interest in these classes of hypersingular integral equations is due to their occurrence in many physical applications. In particular, investigations into the scattering of acoustic waves by moving objects and the study of dynamic Griffith crack problems has necessitated a computationally efficient technique …

Analyzing The Effects Of Display Characteristics And Cognitive Variables On Performance Using Keystroke And Eye Movement Data, Orhan E. Beckman

Psychology Theses & Dissertations

Information about how operators use their eyes while interacting with visual displays is often an overlooked aspect of human-computer interaction. Such information is fundamental to assessing the quality of software interfaces and understanding the cognitive processes that underlie operator behavior. Other research evaluating information displays evolved from using reaction time and subjective data as dependent variables to using oculometric measures. In the current research conventional performance measures are coupled with oculometric measures to evaluate the influence display characteristics and cognitive variables have on performance.

Twelve subjects used a software program to complete a series of specified tasks. Subjects were asked …

Vortex Wake And Exhaust Plume Interaction, Including Ground Effect, Ihab Gaber Adam

Mechanical & Aerospace Engineering Theses & Dissertations

Computational modeling and studies of the near-field wake-vortex turbulent flows, far-field turbulent wake-vortex/exhaust-plume interaction for subsonic and High Speed Civil Transport (HSCT) airplane, and wake-vortex/exhaust-plume interaction with the ground are carried out. The three-dimensional, compressible Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The turbulence models of Baldwin and Lomax, one-equation model of Spalart and Allmaras and two-equation shear stress transport model of Menter are implemented with the RANS solver for turbulent-flow modeling.

For the near-field study, computations are carried out on a fine grid for a rectangular wing with a NACA-0012 airfoil section and …

The Cluster Multipole Algorithm For Far-Field Computations, Rakesh R. Patel

Electrical & Computer Engineering Theses & Dissertations

Computer simulations of N-body systems are beneficial to study the overall behavior of a number of physical systems in fields such as astrophysics, molecular dynamics, and computational fluid dynamics. A new approach for computer simulations of N-body systems is proposed in this research. The new algorithm is called the Cluster Multipole Algorithm (CMA). The goals of the new algorithm are to improve the applicability to non-point sources and to provide more control on the accuracy over current algorithms. The algorithm is targeted to applications that do not require rebuilding the data structure about the system every time step due to …

The Geomorphological History Of An Alluvial Fan Complex In Nelson County, Virginia, Melinda Ann Youngblood

OES Theses and Dissertations

An alluvial fan complex blankets a portion of the Rockfish Valley in Nelson County Virginia, located along the eastern slope of the Blue Ridge Mountains. The seven-km² field area contains three mappable relict alluvial surfaces (Qf1, Qf2, and Qf3) and one modern surface (Qa1), each of which is underlain by fluvial deposits dominated by greenstone and charnokite cobbles. The four surfaces were mapped according to topographic position and degree of stream dissection. Alluvial deposits underlying each surface were characterized using a 3-part clast weathering scale based on greenstone clast weathering rinds and using soil development criteria (clay content, Munsell …

Modeling Environmental Effects On Msx Prevalence And Intensity In Eastern Oyster (Crassostrea Virginica) Populations, Michelle Christine Paraso

OES Theses and Dissertations

An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease. Simulations with this model were designed to investigate the effect of increased or decreased spring freshwater discharge, the timing of high freshwater runoff, the presence or absence of a fall or late spring phytoplankton bloom, and the occurrence of a warm winter on MSX prevalence and intensity in Delaware Bay oyster populations. Model simulations for the lower Bay site …

Reaction-Diffusion Models Of Cancer Dispersion, Kim Yvette Ward

Mathematics & Statistics Theses & Dissertations

The phenomenological modeling of the spatial distribution and temporal evolution of one-dimensional models of cancer dispersion are studied. The models discussed pertain primarily to the transition of a tumor from an initial neoplasm to the dormant avascular state, i.e. just prior to the vascular state, whenever that may occur. Initiating the study is the mathematical analysis of a reaction-diffusion model describing the interaction between cancer cells, normal cells and growth inhibitor. The model leads to several predictions, some of which are supported by experimental data and clinical observations $\lbrack25\rbrack$. We will examine the effects of additional terms on these characteristics. …

Studies Of Warm-Core Rings Using A Particle-In-Cell Method, John James Holdzkom Ii

OES Theses and Dissertations

A particle-in-cell (PIC) model is developed and applied to problems involving the evolution of warm-core rings. Such models are a hybrid of conventional Eulerian and Lagrangian models. They are ideally suited for problems in which a lower layer outcrops to the surface, such as at the boundary of a ring.

The model is developed in three implementations. First, for purposes of model validation, a reduced gravity model is described. The PIC model reproduces the essential characteristics of analytical solutions to the reduced gravity equations and integral invariants are conserved to a high degree. Next, a 1.5-layer model is developed and …

Study Of Human Factors Variables In Battle Outcome Prediction Models, David Andrew Glovier

Engineering Management & Systems Engineering Theses & Dissertations

Over time there have been many improvements in models that are used to predict the outcome of battles. Currently there is much supposition and speculation surrounding the use of human performance related factors as additional inputs to battle simulation models to improve their accuracy. However there is no conclusive scientific evidence which shows that these factors do make a significant difference. This study investigates the use of factors that may impact on the human performance directly or indirectly in battle prediction models. These factors consist of traditional human factors and external factors that may influence the human performance. The research …

A Paleoenvironmental Study Of A Middle Wisconsinan Biota Site, Russell County, Virginia, Thomas C. Wynn

OES Theses and Dissertations

The study area lies in a first-order valley on the northwestern slope of Clinch Mountain that drains into Moccasin Creek. The deposit is 50 m long, 25 m wide and approximately 10 m thick and overlies the Ordovician Moccasin Formation. Preserved within the deposit are mammoth and mastodon bones, logs, and plant macrofossils. Radiocarbon analyses indicate the age of the organic-rich sediments ranges from 29, I 00 BP to >44,000 BP, a time period with no fossil remains reported in this region of the Appalachians. Analyses of field observations, textural data, organic carbon content, and plant macrofossils indicate the organic-rich …

Sparse Equation-Eigen Solvers For Symmetric/Unsymmetric Positive-Negative-Indefinite Matrices With Finite Element And Linear Programming Applications, Hakakizumwami Birali Runesha

Civil & Environmental Engineering Theses & Dissertations

Vectorized sparse solvers for direct solutions of positive-negative-indefinite symmetric systems of linear equations and eigen-equations are developed. Sparse storage schemes, re-ordering, symbolic factorization and numerical factorization algorithms are discussed. Loop unrolling techniques are also incorporated in the coding to enhance the vector speed. In the indefinite solver, which employs various pivoting strategies, a simple rotation matrix is introduced to simplify the computer implementation. Efficient usage of the incore memory is accomplished by the proposed "restart memory management" schemes. A sparse version of the Interior Point Method, IPM, has also been implemented that incorporates the developed indefinite sparse solver for linear …

Inversion And Analysis Of Remotely Sensed Atmospheric Water Vapor Measurements At 940nm, Jack Cutler Larsen

Mechanical & Aerospace Engineering Theses & Dissertations

The understanding and acceptance of remotely sensed atmospheric data depends strongly on the steps taken to characterize experiment error and validate observations through comparisons to other independent measurements. A formal error analysis of the Stratospheric Aerosol and Gas Experiment II (SAGE II) water vapor operational inversion algorithm is performed and compared to previous results. Random measurement errors were characterized by segmented least-squares profile fitting of the slant path absorption which found the error to be uncorrelated in the stratosphere with estimated variances significantly smaller than expected from 18-30 km. Estimates of null space error were developed from radiosonde hygrometers in …

The Effects Of Fabry-Perot Fringing On The Sensitivity Of A Wavelength Modulation Experiment, Patrick C. Shea

Electrical & Computer Engineering Theses & Dissertations

Parasitic Fabry-Perot etaloning plagues many experiments which use wavelength modulation spectroscopy. This fringing, which is an artifact that almost always appears in such experiments, arises from multiple reflections in the optical elements in the experimental apparatus. The etaloning plays a detrimental role and limits the ultimate sensitivity of wavelength modulation spectroscopy experiments. The research described in this thesis investigates this phenomenon. Experimental results are presented which show that when the Q-factor of the parasitic etalon is smaller that that of the absorption line being measured, significant improvement in the Signal to Fringe Noise Ratio can be obtained through the use …

Mathematical Models Of Tumors And Their Remote Metastases, Carryn Bellomo

Mathematics & Statistics Theses & Dissertations

Clinical observations and indications in the literature have led us to investigate several models of tumors. For example, it has been shown that a tumor has the ability to send out anti-growth factors, or inhibitors, to keep its remote metastases from growing. Thus, we model the depleting effect of such a growth inhibitor after the removal of the primary tumor (thus removing the source) as a function of time t and distance from the original tumor r.

It has also been shown clinically that oxygen and glucose are nutrients critical to the survival and growth of tumors. Thus, we model …

Explosive Vapor Generation And Sampling In Conjunction With Ion Mobility Spectrometry, Saeed H. Almeer

Chemistry & Biochemistry Theses & Dissertations

The primary objective of this research is to develop an inexpensive and reliable method to generate vapor pulses of explosives using 2,4,6-trinitrotoluene TNTl for proof of concept. A secondary objective is to demonstrate the use of the vapor generator in various applications keeping in mind potential field scenarios involving explosives. A vapor generator/collector system was developed which gives reproducible pulses of TNT vapors at nanogram levels. The use of this technology was demonstrated in evaluating different surfaces for vapor adsorption of TNT in conjunction with ion mobility spectrometry as the primary analytical tool. Of the materials examined, Teflon was by …

Non-Volatile Dissolved Organic Iodine In Marine Water, Xianhao Cheng

OES Theses and Dissertations

An analytical scheme for the determination of marine DOI has been established. The concentration of DOI is estimated as total iodine (TI) minus total inorganic iodine (TII). The concentration of total iodine is determined as [special characters omitted] after DOI has been oxidized to inorganic iodine quantitatively by intensive UV-irradiation and all the inorganic iodine in the samples had been converted to [special characters omitted] by the addition of NaClO.

Production of DOI in seawater can be via both non-phytoplankton and phytoplankton related processes. In the former, iodide is converted to DOI. In the latter, most likely, iodate is converted …

Error-Correcting Codes Associated With Generalized Hadamard Matrices Over Groups, Iem H. Heng

Mathematics & Statistics Theses & Dissertations

Classical Hadamard matrices are orthogonal matrices whose elements are ±1. It is well-known that error correcting codes having large minimum distance between codewords can be associated with these Hadamard matrices. Indeed, the success of early Mars deep-space probes was strongly dependent upon this communication technology.

The concept of Hadamard matrices with elements drawn from an Abelian group is a natural generalization of the concept. For the case in which the dimension of the matrix is q and the group consists of the p-th roots of unity, these generalized Hadamard matrices are called “Butson Hadamard Matrices BH(p, q)”, …

A Framework For Controlling Quality Of Sessions In Multimedia Systems, Alaa S. Youssef

Computer Science Theses & Dissertations

Collaborative multimedia systems demand overall session quality control beyond the level of quality of service (QoS) pertaining to individual connections in isolation of others. At every instant in time, the quality of the session depends on the actual QoS offered by the system to each of the application streams, as well as on the relative priorities of these streams according to the application semantics. We introduce a framework for achieving QoSess control and address the architectural issues involved in designing a QoSess control laver that realizes the proposed framework. In addition, we detail our contributions for two main components of …

An Alternative Method For Determining Adjusted Function Points As The Basis For Software Cost Estimating, William Alexander Eldred

Engineering Management & Systems Engineering Theses & Dissertations

As software costs become an increasingly higher percentage of total computer system costs, it becomes increasingly more important for software development managers to have the ability to predict development costs with reasonable accuracy early in the software development cycle. Software development cost estimates are based in large measure on software size. Function points are considered by many to be a de facto industry standard as a size metric. The function points technique, unlike lines-of-code, can be applied early in the software development cycle and is language independent. Critics claim that the function point “value adjustment factor,” which purports to capture …

A Hierarchical Filtering-Based Monitoring Architecture For Large-Scale Distributed Systems, Ehab Salem Al-Shaer

Computer Science Theses & Dissertations

On-line monitoring is essential for observing and improving the reliability and performance of large-scale distributed (LSD) systems. In an LSD environment, large numbers of events are generated by system components during their execution and interaction with external objects (e.g. users or processes). These events must be monitored to accurately determine the run-time behavior of an LSD system and to obtain status information that is required for debugging and steering applications. However, the manner in which events are generated in an LSD system is complex and represents a number of challenges for an on-line monitoring system. Correlated events axe generated concurrently …