Digital Commons Network^™

Virtual Compton Scattering In The Nucleon Resonance Region, Luminita Anca Todor

Physics Theses & Dissertations

This thesis is a study of virtual Compton scattering reaction in which a virtual photon is elastically scattered off a proton γv p → γp. The p( e,e′p)γ reaction was measured in the nucleon resonance region for the first time in the experiment E93-050 in Hall A at Thomas Jefferson National Accelerator Facility. To lowest order in ^αQED, this reaction is a coherent superposition of radiation from the incident or scattered electron in elastic ep scattering (Bethe-Heitler) and exclusive production of a photon on the proton, by absorption of a virtual photon …

The Ups Prototype: An Experimental End-User Service Across E-Print Archives, Herbert Van De Sompel, Thomas Krichel, Michael L. Nelson, Patrick Hochstenbach, Victor Lyapunov, Kurt Maly, Mohammad Zubair, Mohamed Kholief, Xiaoming Liu, Heath O'Connell

Computer Science Faculty Publications

A meeting was held in Santa Fe, New Mexico, October 21-22, 1999, to generate discussion and consensus about interoperability of publicly available scholarly information archives. The invitees represented several well known e-print and report archive initiatives, as well as organizations with interests in digital libraries and the transformation of scholarly communication. The central goal of the meeting was to agree on recommendations that would make the creation of end-user services -- such as scientific search engines and linking systems -- for data originating from distributed and dissimilar archives easier. The Universal Preprint Service (UPS) Prototype was developed in preparation for …

Adaptive Object-Oriented Filtering Framework For Event Management Applications, Ehab Al-Shaer, Mohamed Fayad, Hussein Abdel-Wahab, Kurt Maly

Computer Science Faculty Publications

Event filtering is an essential element in event management applications. In event management environments, the filtering mechanisms are employed to track the events generated from applications at run-time and perform the corresponding appropriate actions. Several key applications domains, such as system and network management, distributed system toolkits, communication protocols and active databases, utilize event filtering for various management purposes. The goal of this paper is to describe the object-oriented design and implementation of an adaptive event filtering framework which can be integrated and reused efficiently to develop event management applications for various domain environments. In our approach, the event filtering …

Textured Mos 2 Thin Films Obtained On Tungsten: Electrical Properties Of The W/Mos 2 Contact, E. Gourmelon, J. C. Bernède, J. Pouzet, S. Marsillac

Electrical & Computer Engineering Faculty Publications

Textured films of molybdenum disulfide have been obtained by solid state reaction between the constituents in thin films form when a (200) oriented tungsten sheet is used as substrate. The crystallites have their c axis perpendicular to the plane of the substrate. The annealing conditions are T=1073K and t=30 min. The films are stoichoimetric and p type. Such highly textured films are achieved without foreign atom addition (Ni, Co...). It appears, as shown by x-ray photoelectron spectroscopy, that a thin WS₂ layer is present at the interface W/MoS₂. The crystallization process is discussed by a …

The Influence Of Selected Noncognitive Variables On The Academic Success Of Urban Black High School Males In An Enrichment Pre-College Program, Leon Rouson

Theses and Dissertations in Urban Services - Urban Education

The thrust of this study was to examine the influence of selected noncognitive variables on the academic success of urban Black high school males in an enrichment Pre-College Program. The major research question was: Which of the selected noncognitive variables are most useful in predicting academic success for urban Black high school males?

This study reinvestigated Sedlacek and Brooks' (1976) proposed set of seven noncognitive variables related to academic success: (a) self-concept; (b) realistic self-appraisal; (c) understanding of and ability to deal with racism; (d) preference for long-term goals over more immediate, short-term needs; (e) availability of a strong support …

Piezoceramic Actuator Placement For Acoustic Control Of Panels, Jeffrey S. Bevan

Mechanical & Aerospace Engineering Theses & Dissertations

Optimum placement of multiple traditional piezoceramic actuators is determined for active structural acoustic control of flat panels. The structural acoustic response is determined using acoustic radiation filters and structural surface vibration characteristics. Linear Quadratic Regulator (LQR) control is utilized to determine the optimum state feedback gain for active structural acoustic control. The optimum actuator location is determined by minimizing the structural acoustic radiated noise using a modified genetic algorithm. Experimental tests are conducted and compared to analytical results.

Anisotropic piezoceramic actuators exhibit enhanced performance when compared to traditional isotropic piezoceramic actuators. As a result of the inherent isotropy, these advanced …

Quantitative Analysis Of Ultra-Fine Goethite In Rust Layer On Steel Using Mossbauer And X-Ray Diffraction Spectroscopy, Masato Yamashita, Toshihei Misawa, H. E. Townsend, D. C. Cook

Physics Faculty Publications

We have proposed determination procedure of the relative amounts of rust constituents of steel. Mossbauer spectroscopy provides the relative amounts of crystalline rust constituents including ultra-fine crystals. A quantitative analysis of ultra-fine crystals is possible with the resolution of several percent by comparing the Mossbauer results with the relative amounts of rust constituents determined by X-ray diffraction spectroscopy.

Renormalons As Dilation Modes In The Functional Space, A. Babansky, I. Balitsky

Physics Faculty Publications

There are two possible sources of the factorial large-order behavior of a typical perturbative series. First, the number of different Feynman diagrams may be large; second, there may be abnormally large diagrams known as renormalons. It is well known that the large combinatorial number of diagrams is described by instanton-type solutions of the classical equations. We demonstrate that, from the functional-integral viewpoint, the renormalons do not correspond to a particular configuration but manifest themselves as dilatation modes in the functional space.

Deeply Virtual Compton Scattering At Small X, Ian Balitsky, Elena Kuchina

Physics Faculty Publications

We calculate the cross section of deeply virtual Compton scattering at large energies and intermediate momentum transfers.

High Energy Effective Action From Scattering Of Shock Waves In Qcd, Ian Balitsky

Physics Faculty Publications

The author demonstrates that the amplitude for high-energy scattering can be factorized as a convolution of the contributions due to fast and slow fields. The fast and slow fields interact by means of Wilson-line operators -- infinite gauge factors ordered along the straight line. The resulting factorization formula gives a starting point for a new approach to the effective action for high-energy scattering in QCD.

A Simplified Model Of Wound Healing - Ii: The Critical Size Defect In Two Dimensions, J. S. Arnold, John A. Adam

Mathematics & Statistics Faculty Publications

Recently, a one-dimensional model was developed which gives a reasonable explanation for the existence of a Critical Size Defect (CSD) in certain animals [1]. In this paper, we examine the more realistic two-dimensional model of a circular wound of uniform depth to see what modifications are to be found, as compared with the one-dimensional model, in studying the CSD phenomenon. It transpires that the range of CSD sizes for a reasonable estimate of parameter values is 1 mm-1 cm. More realistic estimates await the appropriate experimental data.

Three-Dimensional Reconstructions Of Tadpole Chondrocrania From Historical Sections, Gary Radice, Mary K. Boggiano, Mark Desantis, Peter Larson, Joseph Oppong, Matthew Smetanick, Todd Stevens, James Tripp, Rebecca Weber, Michael Kerckhove, Rafael De Sá

Virginia Journal of Science

Reconstructing three dimensional structures (3DR) from histological sections has always been difficult but is becoming more accessible with the assistance of digital imaging. We sought to assemble a low cost system using readily available hardware and software to generate 3DR for a study of tadpole chondrocrania. We found that a combination of RGB can1era, stereomicro­scope, and Apple Macintosh PowerPC computers running NIH Image, Object Image, Rotater, and SURFdriver software provided acceptable reconstruc­tions. These are limited in quality primarily by the distortions arising from histological protocols rather than hardware or software.

A Generic Object-Oriented Random Variate Model For Discrete Event Simulations Separating The Data Model From The Process Model, Palathingal Frank

Computational Modeling & Simulation Engineering Theses & Dissertations

Data is the lifeline of any simulation model. The validity of the data is a primary determining factor on the accuracy of a simulation. Hence the data model is an important part of any simulation model. But this is, in most occasions, the most neglected part of any model. Most people view the model correctness in te1ms of the process model functionality rather than the data that is being used in the simulation. As simulation gets more accepted as a reliable problem-solving tool, it is increasingly important to pay careful attention to the accuracy of the simulation and that can …

Evaluation Of The Transport Properties Of Gasb For Bipolar Applications Through Monte Carlo Simulations, Damayanthi Palaniappan

Electrical & Computer Engineering Theses & Dissertations

GaAs is currently the semiconductor material of choice for high speed, low power applications. Its electronic transport properties are superior to almost all other semiconductors. It is also used in a variety of bipolar applications such as photodetectors and photo-mixers. However, as is well known, the hole mobility and related transport parameters of GaAs are not very good. This is a serious drawback, and poses a potential problem for all applications involving bipolar conductivity. In order to increase the high :frequency limits and high-speed capability of bipolar devices, the choice of an alternative material, therefore, becomes necessary. An important first …

Humic Substances As Interferences In The Analysis Of Nitrite In Water, Stephanie Ann Tebault

Chemistry & Biochemistry Theses & Dissertations

Humic substances are of current interest because of their roles in environmental processes involving pollutants. It is also becoming recognized that humic substances may interfere in analysis of environmental samples though the possible adverse effects do not appear to be fully appreciated. The present effort focuses on determining whether humic materials interfere in the analysis of nitrite in water using the Griess reaction. This is a well-known reaction using nitrosation to gjve a diazonium salt followed by coupling with an appropriate reagent to form a dye. This colorimetric method continues to be applied in the laboratory and the field for …

A Pressure Transducer Using Field Emitter Arrays, Mark David Richmond

Electrical & Computer Engineering Theses & Dissertations

A new pressure sensing device using field emission from diamond coated silicon tips has been developed. A high electric field applied between a nano-tip array and a diaphragm configured as electrodes produces electron emission governed by the Fowler - Nordheim equation. The electron emission is very sensitive to the separation between the diaphragm and the tips, which is fixed at an initial spacing and bonded such that a cavity is created between them. Pressure applied to the diaphragm decreases the spacing between the electrodes, thereby increasing the number of electrons emitted.

Silicon has been used as a substrate on which …

A Simplified Model Of Wound Healing (With Particular Reference To The Critical Size Defect), J. A. Adam

Mathematics & Statistics Faculty Publications

This paper is an attempt to construct a simple mathematical model of wound healing/tissue regeneration which reproduces some of the known qualitative features of those phenomena. It does not address the time development of the wound in any way, but does examine conditions (e.g., wound size) under which such healing may occur. Two related one-dimensional models are examined here. The first, and simpler of the two corresponds to a "swath" of tissue (or more realistically in this case, bone) removed from an infinite plane of tissue in which only a thin band of tissue at the wound edges takes part …

Virginia Academy Of Science 1999 Best Student Paper Awards

Virginia Journal of Science

List of award winning student papers by section from the Virginia Academy of Science, 1999

Abstracts Of Papers, 77th Annual Meeting Of The Virginia Academy Of Science, May 26-28, 1999, Old Dominion University, Norfolk, Virginia

Virginia Journal of Science

This document is a list of abstracts presented at the 77th annual meeting of the Virginia Academy of Science, between May 26 and May 28th, 1999, at Old Dominion University.

Virginia Junior Academy Of Science Awards, 1999 Annual Meeting

Virginia Journal of Science

List of award winning student papers by section from the 1999 Annual Meeting of the Virginia Junior Academy of Science

Zinc Speculation And Ligand Fluxes In Chesapeake Bay And Elizabeth River Pore Waters, Duncan Glover Byers

Chemistry & Biochemistry Theses & Dissertations

Presented here are the first data on the vertical concentrations, complexation, speciation, and fluxes of total dissolved zinc and zinc complexing ligands, and zinc speciation in sediment pore waters in the Chesapeake Bay and Elizabeth River, Virginia.

Sediment pore waters were collected in mid and southern Chesapeake Bay in November 1997 and in the Elizabeth River (Pinner's Point) in March, April, and July 1998. Flux experiments were conducted in Elizabeth River sediment cores in April and July 1998. [TDZn] and zinc complexation were determined using differential pulse anodic stripping voltammetry at a hanging mercury drop electrode (DPASV-HMDE).

[TDZn] in the …

Generation Of Human Chorionic Gonadotropin Beta Subunit Specific Monoclonal Antibody Using A Synthetic Peptide, Zhe Huang

Chemistry & Biochemistry Theses & Dissertations

Human chorionic gonadotropin (hCG) is well known for early immunological and bioassay tests for early detection of pregnancy. Since the hormone specific beta subunit confers unique biological and immunological specificity to hCG, immunochemical measurement of hCG has achieved greater specificity and sensitivity in recent years by using either the beta subunit as an immunogen or a partially reduced beta subunit polypeptide chain. However, antiserum raised against the entire hCG beta subunit usually cross-reacts to some extent with human luteinizing hormone (hLH). hCG has been found to be present in the extract of tumors and minute quantities of hCG are synthesized …

Nitrate Reductase Activity, Nitrate Uptake And Iodine Speciation In The Marine Environment, Chin-Chang Hung

OES Theses and Dissertations

The present method for the determination of new production (NP) by measuring the uptake of added ¹⁵NO₃^– suffers from a number of limitations. In an attempt to improve this situation, this research examined the possibility of estimating ¹⁵NO₃– uptake by measuring the activity of nitrate reductase (NRA). In addition, because it has long been suspected that the biological reduction of IO₃^– to I^– may be mediated by nitrate reductase (NR), this research investigated the ability of NR to catalyze the reduction of iodate to iodide.

An improved method for the determination …

Large Amplitude Pitching Of Supermaneuver Delta Wings Including Flow Control, Yahia A. Abdelhamid

Mechanical & Aerospace Engineering Theses & Dissertations

The unsteady, three-dimensional Navier-Stokes equations are solved to simulate and study the aerodynamic response of a delta wing undergoing large amplitude pitching motion up to 90° angle of attack. The primary model under consideration consists of a 76° swept, sharp-edged delta wing of zero thickness, initially at zero angle of attack. The freestream Mach number and Reynolds number are 0.3 and 0.45 × 106, respectively. The governing equations are solved time-accurately using the implicit, upwind, Roe flux-difference splitting, finite-volume scheme. Both laminar and turbulent flow solutions are investigated. In the laminar flow solutions, validation of the computational results is carried …

A Family Of Hierarchical Encoding Techniques For Image And Video Communications, Samah A. Senbel

Computer Science Theses & Dissertations

As the demand for image and video transmission and interactive multimedia applications continues to grow, scalable image and video compression that has robust behavior over unreliable channels are of increasing interest. These desktop applications require scalability as a main feature due to its heterogeneous nature, since participants in an interactive multimedia application have different needs and processing power. Also, the encoding and decoding algorithm complexity must be low due to the practical considerations of low-cost low-power receiver terminals. This requires image and video encoding techniques that jointly considers compression, scalability, robustness, and simplicity.

In this dissertation, we present a family …

Traning Strategy Use And Its Effects On Working Memory Capacity, Jennifer Lynn Scott

Psychology Theses & Dissertations

Two experiments were conducted to examine whether strategy use affects the storage component of a working memory task. In Experiment 1, all 21 participants were given training to create stories from lists of to-be-remembered words (i.e., chaining) within a short-term memory task (i.e., including only a storage task). Short-term memory task performance and working memory span task performance were examined before and after training. Both short-term memory and working memory task performance improved from pretest to post-test. In Experiment 2, the same strategy training was given to 30 participants. In addition, another 30 participants were assigned to a control condition. …

Ls-Dyna3d Modeling And Simulation For Uncontained Engine Debris Impact On Fuselage Skins, Robin Eileen Lawson

Mechanical & Aerospace Engineering Theses & Dissertations

Impact and penetration events for uncontained engine debris on fuselage skins are simulated using the LS-DYNA3D finite element analysis code. The LS-DYNA3D code is a nonlinear transient dynamic simulation tool with contact algorithms for impact. A finite element analysis is used to simulate the penetration of aluminum plates impacted by titanium impactors on aircraft-like skin panels. By gaining a more comprehensive understanding of this dynamic impact event, this work is meant to contribute to improving designs for damage tolerance and residual strength by providing modeling and analysis guidelines for the analyst.

Parametric studies are performed to determine the influence of …

Development And Application Of Adaptive Dynamic Grids For Wake Vortex/Ground Interaction, Ilker Emin Türkgeldi

Mechanical & Aerospace Engineering Theses & Dissertations

An adaptive and dynamic grid approach is developed for the numerical computations of wake vortex flow problems with ground interaction. The unnecessary grid points at the far field of the original, large, single zone grid are removed for computational efficiency. Next, the grid is modified into an adaptive one, where the fine core region keeps track of the vortices and can be split into two regions when the vortex separation distance exceeds a specified limit length. In the final step a multi zonal feature is added to this grid by means of two embedded grids placed at the vortex centers …

Newton Parameter Update Algorithm For Recurrent Neural Networks Applied To Adaptive System Identification And Control, Donald Allen Gates

Electrical & Computer Engineering Theses & Dissertations

This paper shows that the combination of a second-order neural network parameter update algorithm and internal network feedback can be effectively used for adaptive, nonlinear, dynamical system identification and control. Adaptive neural identification and control algorithms are typically utilized for real-time applications where the rate of adaptation is often critical. A fast, adaptive network parameter update algorithm is presented.

Simulation results show that this algorithm is capable of quickly identifying and adapting to changes in system parameters, making it feasible to use for real-time control and fault accommodation applications.

Dynamic And Interactive 3d Simulation Over The World Wide Web, Rajesh Vennam

Electrical & Computer Engineering Theses & Dissertations

The thesis presents the development of a new and novel three-dimensional simulation tool over the WWW using Virtual Reality Modeling Language (VRML). VRML is a 3D analog to HTML and serves as a simple, multiplatform language for publishing 3D Web pages. In general, most people use VRML for developing three-dimensional models or worlds that provide little or no interaction for the users. This tool combines interaction and dynamic object creation. A thorough study of VRML is done to explore the features of VRML that could be combined to develop methodologies for creation of dynamic and interactive 3D objects over the …