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William & Mary

Theses/Dissertations

2000

Articles 31 - 43 of 43

Full-Text Articles in Physical Sciences and Mathematics

Precision Measurements Of The Proton And Deuteron Polarized Structure Functions, Paul Mcconihay King Ii Jan 2000

Precision Measurements Of The Proton And Deuteron Polarized Structure Functions, Paul Mcconihay King Ii

Dissertations, Theses, and Masters Projects

Experiment E155 at the Stanford Linear Accelerator Center measured the longitudinal and transverse polarized deep-inelastic scattering asymmetries for the proton and deuteron using longitudinally-polarized electron beams with energies of 48.3 GeV and 38.8 GeV, respectively. The electron beam polarization was measured by Moller polarimetry to be 0.81 +/- 0.02. Dynamically-polarized solid 15N3 and 6Li2H were used as the target materials. The scattered electrons were detected in three independent spectrometers at 2.75??, 5.5??, and 10.5??, covering a kinematic range of 0.014 ≤ x ≤ 0.9 and 1.0(GeV/ c)2 ≤ Q2 ≤ 40(GeV/ c)2. The 10.5?? spectrometer was constructed for this experiment. …

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Plasma Source Ion Implantation Of High Voltage Electrodes, Thomas Joseph Venhaus Jan 2000

Plasma Source Ion Implantation Of High Voltage Electrodes, Thomas Joseph Venhaus

Dissertations, Theses, and Masters Projects

Field emission and breakdown characteristics of high voltage, large area electrodes determine the performance of many vacuum-based electron sources. A corroborative project with the Thomas Jefferson National Accelerator Facility involves studying the behavior of such electrodes after nitrogen ion implantation. A Plasma Source Ion Implantation (PSII) facility is designed and constructed at William and Mary, and used to treat stainless steel electrodes. PSII is a novel implantation technique developed at the University of Wisconsin-Madison. A workpiece is submerged in a quiescent plasma of the species to be implanted. A series of high, negative voltages (30--100 kV) is applied to the …

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Theoretical And Experimental Study Of Generation Mechanisms For Laser Ultrasound In Woven Graphite /Epoxy Composites With Translaminar Stitching, Adam D. Friedman Jan 2000

Theoretical And Experimental Study Of Generation Mechanisms For Laser Ultrasound In Woven Graphite /Epoxy Composites With Translaminar Stitching, Adam D. Friedman

Dissertations, Theses, and Masters Projects

The aerospace industry is beginning to use advanced composite materials for primary load bearing structures and their failure mechanisms must be better understood to predict their behavior in service. The Combined Loads Tests (COLTS) facility is being constructed at the NASA Langley Research Center to characterize these failure mechanisms. Laser based ultrasonic NDE can monitor the samples during dynamic loading without interfering with the structural tests. However, the constraints of implementing laser ultrasound in a structures laboratory reduces the efficiency of the technique. The system has to be "eye-safe" because many people will be present during the structural tests. Consequently, …

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Redistribution Of Rydberg States By Terahertz Radiation, Jonathan David Curley Jan 2000

Redistribution Of Rydberg States By Terahertz Radiation, Jonathan David Curley

Dissertations, Theses, and Masters Projects

We present the technique and results of our study of the redistribution of Rydberg states in barium by a half cycle pulse (HCP). A survey of previous research concerning the interaction of half cycle pulses with Rydberg atoms reveals a lack of experimental data in the area of state redistribution. This is primarily due to an inability to identify the redistributed states accurately using the currently available tool: selective field ionization (SFI). We present the limitations of SFI as a state identification tool. We then present a survey of isolated core excitation as a state identification tool, along with its …

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Structural Instabilities In Strontium Titanate From First-Principles Calculations, Christopher A. Lasota Jan 2000

Structural Instabilities In Strontium Titanate From First-Principles Calculations, Christopher A. Lasota

Dissertations, Theses, and Masters Projects

For some time now, first-principles calculation methods have proven to be an effective tool for investigating the physics of condensed matter systems. The additional use of density functional theory (DFT) and the local density approximation (LDA) has permitted even complex materials to be studied on desktop workstations with remarkable success. The incorporation of linear response theory into these methods has extended their power, allowing investigation of important dynamical properties.;Contained within the following pages are the results of a first-principles study of SrTiO3. This transition metal oxide is often grouped with ferroelectric materials, due to its similar composition and perovskite structure. …

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Studies In Hard Pion Photoproduction, Christian Jens Wahlquist Jan 2000

Studies In Hard Pion Photoproduction, Christian Jens Wahlquist

Dissertations, Theses, and Masters Projects

The production of high transverse momenta mesons via polarized photoproduction can be a means of determining the parton structure of the target. at the regions of highest transverse pion momenta, kT, it can be shown that short distance, direct, pion production dominates and is sensitive to the polarized quark distributions. as the produced pions transverse momenta decreases the importance of pions produced through fragmentation following photon-gluon fusion increases. This process give us sensitivity to the form of the polarized gluon distribution. Both processes are calculable with perturbative Quantum Chromodynamics (pQCD) due to the high kT of the pion produced. Numerical …

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An Interactive Simulation Environment For End-To-End Digital Imaging System Design And Fidelity Analysis, Moira Joyce Turner Jan 2000

An Interactive Simulation Environment For End-To-End Digital Imaging System Design And Fidelity Analysis, Moira Joyce Turner

Dissertations, Theses, and Masters Projects

The detailed specification, implementation, and documentation of an interactive software environment based on a continuous/discrete/continuous imaging system model is presented. The purpose of the interactive environment is to support the design and performance analysis of end-to-end digital imaging systems. Development of the environment is based on the objectives of acceptable response time, large sampling grid capability, good graphical user interface design, independence from proprietary applications and portability among UNIX workstations. While one-dimensional variations of interactive design environments have been developed by the commercial active filter design community, there is little or no evidence that the increased complexity associated with the …

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Accelerating The Simulation Of Wireless Cellular Systems, Luiz Felipe Perrone Jan 2000

Accelerating The Simulation Of Wireless Cellular Systems, Luiz Felipe Perrone

Dissertations, Theses, and Masters Projects

The simulation of comprehensive models for cellular wireless systems poses a computational burden of great proportions. When a sub-model for transmitter power level control is included in the simulation, a continuous process in discrete-time is introduced, requiring traditional execution to advance in small, regular time-steps. to accelerate these simulations, we propose the use of interval jumping, a novel technique which allows time to progress in adaptive, irregularly-sized jumps in time. The foundations for this mechanism are laid out in the light of the simulation of a complex simulation model which includes teletraffic, radio propagation, channel allocation, transmitter power control, and …

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Application Of Genetic Markers To Provide Species Identification And Define Stock Structure: Analyses Of Selected Marine Fishes Of The Mid -Atlantic Bight, Jan F. Cordes Jan 2000

Application Of Genetic Markers To Provide Species Identification And Define Stock Structure: Analyses Of Selected Marine Fishes Of The Mid -Atlantic Bight, Jan F. Cordes

Dissertations, Theses, and Masters Projects

Molecular markers and techniques were employed to develop a genetic key for the forensic identification of 16 species of Chesapeake Bay sportfishes and to investigate the stock structure of one of those species, the weakfish Cynoscion regalis. Regions within the ATP synthetase 6 (ATPase 6), Cytochrome b , cytochrome c oxidase I, NADH dehydrogenase 4 (ND4), and 12S/16S ribosomal RNA mitochondrial genes were amplified using the polymerase chain reaction (PCR) and digested with a bank of restriction endonucleases to find a genetic marker that exhibited complete interspecific differentiation and low intraspecific variation. Complete separation of all sixteen species was accomplished …

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Bioremediation Of Tributyltin Contaminated Sediment Using Spartina Alterniflora In A Created Tidal Wetland, Britt-Anne Anderson Jan 2000

Bioremediation Of Tributyltin Contaminated Sediment Using Spartina Alterniflora In A Created Tidal Wetland, Britt-Anne Anderson

Dissertations, Theses, and Masters Projects

No abstract provided.

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The Habitat Utilization Of Juvenile Hawksbill Sea Turtles (Eretmochelys Imbricata) At Buck Island Reef National Monument, St Croix, U.S Virgin Islands, Roy A. Pemberton Jan 2000

The Habitat Utilization Of Juvenile Hawksbill Sea Turtles (Eretmochelys Imbricata) At Buck Island Reef National Monument, St Croix, U.S Virgin Islands, Roy A. Pemberton

Dissertations, Theses, and Masters Projects

No abstract provided.

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Maturation And Repeat Spawning By American Shad In The York River, Virginia, Kristin L. Maki Jan 2000

Maturation And Repeat Spawning By American Shad In The York River, Virginia, Kristin L. Maki

Dissertations, Theses, and Masters Projects

No abstract provided.

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Biology Of The Spotted Seatrout, Cynoscion Nebulosus, In The Chesapeake Bay Region, Thomas F. Ihde Jan 2000

Biology Of The Spotted Seatrout, Cynoscion Nebulosus, In The Chesapeake Bay Region, Thomas F. Ihde

Dissertations, Theses, and Masters Projects

No abstract provided.

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