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Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

Description: This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intr… more
Date: December 31, 2002
Creator: Agio, Mario
Partner: UNT Libraries Government Documents Department
open access

Scalable Computational Chemistry: New Developments and Applications

Description: The computational part of the thesis is the investigation of titanium chloride (II) as a potential catalyst for the bis-silylation reaction of ethylene with hexaclorodisilane at different levels of theory. Bis-silylation is an important reaction for producing bis(silyl) compounds and new C-Si bonds, which can serve as monomers for silicon containing polymers and silicon carbides. Ab initio calculations on the steps involved in a proposed mechanism are presented. This choice of reactants allows … more
Date: December 31, 2002
Creator: Alexeev, Yuri
Partner: UNT Libraries Government Documents Department
open access

Near Threshold electroproduction of the Omega Meson at Momentum Transfer Q2=0.5 (GeV/c)2

Description: Jefferson Lab kaon experiments E91016/E93018 produced data on both strangeness and vector meson electroproduction. The latter part of the experiments was focused on the electroproduction of the omega meson for momentum transfer Q 2 near 0.5 (GeV/c) 2. This reaction was selected from the inelastic ep channel, H-1 (e, e' p)X, by performing involved signal background separation. Tagging the omega meson production only on electron and proton not only introduced appreciable statistical error but als… more
Date: January 1, 2002
Creator: Ambrosewicz, P.
Partner: UNT Libraries Government Documents Department
open access

Development of Novel Polymeric Materials for Gene Therapy and pH-Sensitive Drug Delivery: Modeling, Synthesis, Characterization, and Analysis

Description: The underlying theme of this thesis is the use of polymeric materials in bioapplications. Chapters 2-5 either develop a fundamental understanding of current materials used for bioapplications or establish protocols and procedures used in characterizing and synthesizing novel materials. In chapters 6 and 7 these principles and procedures are applied to the development of materials to be used for gene therapy and drug delivery. Chapter one is an introduction to the ideas that will be necessary to… more
Date: August 27, 2002
Creator: Anderson, Brian Curtis
Partner: UNT Libraries Government Documents Department
open access

Evaluating Radionuclide Air Emission Stack Sampling Systems

Description: The Pacific Northwest National Laboratory (PNNL) operates a number of research and development (R&D) facilities for the U.S. Department of Energy at the Hanford Site, Washington. These facilities are subject to Clean Air Act regulations that require sampling of radionuclide air emissions from some of these facilities. A revision to an American National Standards Institute (ANSI) standard on sampling radioactive air emissions has recently been incorporated into federal and state regulations and … more
Date: December 16, 2002
Creator: Ballinger, Marcel Y.
Partner: UNT Libraries Government Documents Department
open access

Design and Evaluation of System Configurations for an EUV Mask Inspection Microscope

Description: This document is the third sub-report of the EUV AIM design study being conducted at LLNL on behalf of International Sematech (ISMT). The purpose of this study as identified in section 1.2 of the statement of work is to research the basic user requirements of an actinic defect characterization tool, potential design configurations and top-level specifications. The objectives of this design study specifically identified in section 1.3 of the statement of work were to: (1) Determine the user requ… more
Date: August 20, 2002
Creator: Barty, Anton; Taylor, John S.; Hudyma, Russell & Spiller, Eberhard
Partner: UNT Libraries Government Documents Department
open access

A study of B(s)0 to J/psi phi in the D0 experiment and an example of HEP technology transfer

Description: After years of preparation, data taking with the upgraded D0 detector at the Tevatron proton-antiproton collider has begun. The large amount of data produced in a p{bar p}-collider requires sophisticated triggers to filter out the interesting events. Described in this thesis is the development of trigger software for the newly implemented Silicon Microstrip Tracker. D0 is a multi-purpose detector with a broad physics program. one area being studied at D0 is B mesons. An algorithm for reconstruc… more
Date: January 1, 2002
Creator: Bauer, Daniela Ursula
Partner: UNT Libraries Government Documents Department
open access

The Effect of Oxygen Contamination on the Amorphous Structure of Thermally Sprayed Coatings of Cu47Ti33Zr11Ni8Si1

Description: this research has shown that it is possible to deposit coatings of gas atomized Cu{sub 47}Ti{sub 33}Zr{sub 11}Ni{sub 8}Si{sub 1} powders containing various levels of oxygen contamination using plasma arc spray methods. The structure of the coating was found to depend primarily on the spray environment, with an argon atmosphere producing the most amorphous samples for a given starting powder. The oxygen content of the coatings reflected the relative levels of the oxygen contamination in the star… more
Date: May 27, 2002
Creator: Besser, Matthew Frank
Partner: UNT Libraries Government Documents Department
open access

Study of the Delta (1232) Using Double Polarization Asymmetries

Description: An extensive experimental program to measure the spin structure of the nucleus is underway in Hall B at Jefferson Lab using a polarized electron beam incident on a polarized target. Spin degrees of freedom offer the possibility to test, in an independent way, existing models of resonance electro-production. The present analysis selects the Delta{sup +} (1232) in the exclusive channel {rvec p}({rvec e}, e'p)pi{sup 0} from data of the EG1 run period, taken in the Fall of 1998, to extract single a… more
Date: March 1, 2002
Creator: Biselli, Angela
Partner: UNT Libraries Government Documents Department
open access

Design of Surface micromachined Compliant MEMS

Description: The consideration of compliant mechanisms as Microelectromechanical Systems (MEMS) is the focus of this research endeavor. MEMS are micron to millimeter devices that combine electrical, mechanical, and information processing capabilities on the same device. These MEMS need some mechanical motion or parts that move relative to each other. This relative motion, using multiple parts, is not desired because of the assembly requirement and the friction introduced. Compliant devices limits or elimina… more
Date: August 1, 2002
Creator: Bradley, Joe Anthony
Partner: UNT Libraries Government Documents Department
open access

Design of Surface Micromachined Compliant MEMS

Description: The consideration of compliant mechanisms as Microelectromechanical Systems (MEMS) is the focus of this research endeavor. MEMS are micron to millimeter devices that combine electrical, mechanical, and information processing capabilities on the same device. These MEMS need some mechanical motion or parts that move relative to each other. This relative motion, using multiple parts, is not desired because of the assembly requirement and the friction introduced. Compliant devices limits or elimina… more
Date: December 31, 2002
Creator: Bradley, Joe Anthony
Partner: UNT Libraries Government Documents Department
open access

Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

Description: Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submi… more
Date: December 31, 2002
Creator: Cai, Tanhong
Partner: UNT Libraries Government Documents Department
open access

Studies in High Current Density Ion Sources for Heavy Ion FusionApplications

Description: This dissertation develops diverse research on small (diameter {approx} few mm), high current density (J {approx} several tens of mA/cm{sup 2}) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield (<J>… more
Date: June 1, 2002
Creator: Chacon-Golcher, E.
Partner: UNT Libraries Government Documents Department
open access

Coherence techniques at extreme ultraviolet wavelengths

Description: The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. t… more
Date: October 1, 2002
Creator: Chang, Chang
Partner: UNT Libraries Government Documents Department
open access

Implementation of MP{_}Lite for the VI Architecture

Description: MP{_}Lite is a light weight message-passing library designed to deliver the maximum performance to applications in a portable and user friendly manner. The Virtual Interface (VI) architecture is a user-level communication protocol that bypasses the operating system to provide much better performance than traditional network architectures. By combining the high efficiency of MP{_}Lite and high performance of the VI architecture, they are able to implement a high performance message-passing libra… more
Date: December 31, 2002
Creator: Chen, Weiyi
Partner: UNT Libraries Government Documents Department
open access

Efficient Video Similarity Measurement and Search

Description: The amount of information on the world wide web has grown enormously since its creation in 1990. Duplication of content is inevitable because there is no central management on the web. Studies have shown that many similar versions of the same text documents can be found throughout the web. This redundancy problem is more severe for multimedia content such as web video sequences, as they are often stored in multiple locations and different formats to facilitate downloading and streaming. Similar… more
Date: December 19, 2002
Creator: Cheung, Sen-Cheng S.
Partner: UNT Libraries Government Documents Department
open access

Authenticated group Diffie-Hellman key exchange: theory and practice

Description: Authenticated two-party Diffie-Hellman key exchange allows two principals A and B, communicating over a public network, and each holding a pair of matching public/private keys to agree on a session key. Protocols designed to deal with this problem ensure A (B resp.)that no other principals aside from B (A resp.) can learn any information about this value. These protocols additionally often ensure A and B that their respective partner has actually computed the shared secret value. A natural exte… more
Date: October 3, 2002
Creator: Chevassut, Olivier
Partner: UNT Libraries Government Documents Department
open access

Superconducting High Energy Resolution Gamma-ray Spectrometers

Description: We have demonstrated that a bulk absorber coupled to a TES can serve as a good gamma-ray spectrometer. Our measured energy resolution of 70 eV at 60 keV is among the best measurements in this field. We have also shown excellent agreement between the noise predictions and measured noise. Despite this good result, we noted that our detector design has shortcomings with a low count rate and vulnerabilities with the linearity of energy response. We addressed these issues by implementation of an act… more
Date: February 22, 2002
Creator: Chow, Daniel Tun Lai
Partner: UNT Libraries Government Documents Department
open access

Imaging Catalytic Surfaces by Multiplexed Capillary Electrophoresis With Absorption Detection

Description: A new technique for in situ imaging and screening heterogeneous catalysts by using multiplexed capillary electrophoresis with absorption detection was developed. By bundling the inlets of a large number of capillaries, an imaging probe can be created that can be used to sample products formed directly from a catalytic surface with high spatial resolution. In this work, they used surfaces made of platinum, iron or gold wires as model catalytic surfaces for imaging. Various shapes were recorded i… more
Date: August 27, 2002
Creator: Christodoulou, Michael
Partner: UNT Libraries Government Documents Department
open access

Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

Description: The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methyleneger… more
Date: December 31, 2002
Creator: Classen, Nathan Robert
Partner: UNT Libraries Government Documents Department
open access

The Zintl Chemistry of the Heavy Tetrel Elements

Description: Exploration of the alkali metal/alkaline-earth metal/heavy tetrel (Sn or Pb) systems has revealed a vast array of new chemistry and novel structure types. The structures and properties of these new materials have been studied in an attempt to understand the chemistry of these and other related systems. The first phase reported is Rb{sub 4}Pb{sub 9} (K{sub 4}Pb{sub 9} type). The compound contains two different types of Pb{sub 9}{sup 4-} deltahedra, a monocapped square pyramid and a distorted tri… more
Date: December 31, 2002
Creator: Corbett, John D.
Partner: UNT Libraries Government Documents Department
open access

Aerosol Property Comparison Within and Above the ABL at the ARM Program SGP Site

Description: This thesis determines what, if any, measurements of aerosol properties made at the Earth surface are representative of those within the entire air column. Data from the Atmospheric Radiation Measurement site at the Southern Great Plains, the only location in the world where ground-based and in situ airborne measurements are routinely made. Flight legs during the one-year period from March 2000 were categorized as either within or above the atmospheric boundary layer (ABL) by use of an objectiv… more
Date: May 1, 2002
Creator: Delle Monache, L
Partner: UNT Libraries Government Documents Department
open access

Comparison of Aerosol Properties Within and Above the ABL at the ARM Program's SGP Site

Description: The goal of this thesis is to determine under what conditions, if any, measurements of aerosol properties made at the Earth's surface are representative of aerosol properties within the column of air above the surface. This thesis will use data from the Atmospheric Radiation Measurement (ARM) site at the Southern Great Plains (SGP) which is the only location in the world where ground-based and in situ airborne measurements are made on a routine basis. All flight legs in the one-year period from… more
Date: May 1, 2002
Creator: Delle Monache, L
Partner: UNT Libraries Government Documents Department
open access

Constructing Predictive Estimates for Worker Exposure to Radioactivity During Decommissioning: Analysis of Completed Decommissioning Projects

Description: An analysis of completed decommissioning projects is used to construct predictive estimates for worker exposure to radioactivity during decommissioning activities. The preferred organizational method for the completed decommissioning project data is to divide the data by type of facility, whether decommissioning was performed on part of the facility or the complete facility, and the level of radiation within the facility prior to decommissioning (low, medium, or high). Additional data analysis … more
Date: October 1, 2002
Creator: Dettmers, Dana Lee & Eide, Steven Arvid
Partner: UNT Libraries Government Documents Department
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