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Centrifugal Atomization of Lanthanide Materials for Cryogenic Coolers

Description: Until recently, Pb was the preferred heat exchanger matrix material used in low temperature cryocoolers; however, the heat capacity of Pb drops drastically below {approximately}15K and new matrix materials based on the lanthanide elements have been developed. These materials magnetically order at low temperatures and the entropy change associated with ordering contributes to the materials` heat capacities. The drawback to widespread use of lanthanide intermetallic compounds in cryocoolers has b… more
Date: January 4, 1994
Creator: Osborne, Matthew G.
Partner: UNT Libraries Government Documents Department
open access

Pion single charge exchange in three body nuclei at intermediate energies

Description: The purpose of this thesis is to present new experimental information about modifications to the pion-nucleon single charge exchange interaction, {pi}{sup +}n {yields}{pi}{sup 0} p or {pi}{sup {minus}} p {yields} {pi}{sup 0}n, due to the presence of other nucleons. The results of two experimental studies of pion single charge exchange in the three nucleon system near the {triangle}-resonance are presented. Both of these experiments were performed at the Clinton P. Anderson Meson Physics Facilit… more
Date: January 1, 1994
Creator: Dowell, M. L.
Partner: UNT Libraries Government Documents Department
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Measurement of magnetic turbulence structure and nonlinear mode coupling of tearing fluctuations in the Madison Symmetric Torus reversed field pinch edge

Description: Linear and nonlinear magnetohydrodynamic (MHD) stability of current-driven modes are studied in the MST reversed field pinch. Measured low frequency (f < 35 kHz) magnetic fluctuations are consistent with the global resistive tearing instabilities predicted by 3-D MHD simulations. At frequencies above 35 kHz, the magnetic fluctuations were detected to be localized and externally resonant. Discrete dynamo events, ``sawtooth oscillations,`` have been observed in the experimental RFP plasmas. This … more
Date: January 1, 1994
Creator: Assadi, S.
Partner: UNT Libraries Government Documents Department
open access

Perturbation theory in light-cone quantization

Description: A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the pertu… more
Date: January 1, 1992
Creator: Langnau, A.
Partner: UNT Libraries Government Documents Department
open access

Fate of polycyclic aromatic hydrocarbons in plant-soil systems: Plant responses to a chemical stress in the root zone

Description: Under laboratory conditions selected to maximize root uptake, plant tissue distribution of PAH-derived {sup 14}C was largely limited to root tissue of Malilotus alba. These results suggest that plant uptake of PAHs from contaminated soil via roots, and translocation to aboveground plant tissues (stems and leaves), is a limited mechanism for transport into terrestrial food chains. However, these data also indicate that root surface sorption of PAHs may be important for plants grown in soils cont… more
Date: January 1, 1994
Creator: Hoylman, A. M. & Walton, B. T.
Partner: UNT Libraries Government Documents Department
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Encapsulation of Hazardous Wastes Into Agglomerates

Description: The objective of this study was to investigate the feasibility of using the cementitious properties and agglomeration characteristics of coal conversion byproducts to encapsulate and immobilize hazardous waste materials. The intention was to establish an economical way of co-utilization and co-disposal of wastes. In addition, it may aid in the eradication of air pollution problems associated with the fine-powdery nature of fly ash. Encapsulation into agglomerates is a novel approach of treating… more
Date: January 28, 1992
Creator: Guloy, Aida
Partner: UNT Libraries Government Documents Department
open access

A comparative evaluation of conceptual models for the Snake River Plain aquifer at the Idaho Chemical Processing Plant, INEL

Description: Geologic and hydrologic data collected by the United States Geological Survey (USGS) are used to evaluate the existing ground water monitoring well network completed in the upper portion of the Snake River Plain aquifer (SRPA) beneath the Idaho Chemical Processing Plant (ICPP). The USGS data analyzed and compared in this study include: (a) lithologic, geophysical, and stratigraphic information, including the conceptual geologic models intrawell, ground water flow measurement (Tracejector tests)… more
Date: January 1, 1992
Creator: Prahl, C. J.
Partner: UNT Libraries Government Documents Department
open access

The use of ultraviolet Thomson scattering as a versatile diagnostic for detailed measurements of a collisional laser produced plasma

Description: Collective Thomson scattering from ion-acoustic waves at 266nm is used to obtain spatially resolved, two-dimensional electron density, sound speed, and radial drift profiles of a collisional laser plasma. An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where the electron densities approach n{sub c}/10. Laser plasmas of this type are important because they model some of the aspects of the … more
Date: January 8, 1993
Creator: Tracy, M. D.
Partner: UNT Libraries Government Documents Department
open access

A research study to determine the effect of Total Quality Management (TQM) on employee morale in Plant Procedures Division at EG&G, Rocky Flats, Inc.

Description: EG&G at Rocky Flats, Golden, Colorado, experienced a high amount of low morale, due to the plant site having been designated to close, and the uneasiness of the working force was very visible. Some employees accepted early retirement in October 1992, however, all received letters of 120 days notice in March 1993, and were advised several cuts Would be made by October 1, 1993. This information alone caused many insecurities in employees, and caused morale to decrease even more. This is an in dep… more
Date: January 1, 1994
Creator: Casey, E. F.
Partner: UNT Libraries Government Documents Department
open access

Low frequency ultrasonic nondestructive inspection of aluminum/adhesive fuselage lap splices

Description: This thesis is a collection of research efforts in ultrasonics, conducted at the Center for Aviation Systems Reliability located at Iowa State University, as part of the Federal Aviation Administration`s ``Aging Aircraft Program.`` The research was directed toward the development of an ultrasonic prototype to inspect the aluminum/adhesive fuselage lap splices found on 1970`s vintage Boeing passenger aircraft. The ultrasonic prototype consists of a normal incidence, low frequency inspection tech… more
Date: January 4, 1994
Creator: Patton, T.
Partner: UNT Libraries Government Documents Department
open access

Theoretical study of the conformation and energy of supercoiled DNA

Description: The two sugar-phosphate backbones of the DNA molecule wind about each other in helical paths. For circular DNA molecules, or for linear pieces of DNA with the ends anchored, the two strands have a well-defined linking number, Lk. If Lk differs from the equilibrium linking number Lk{sub 0}, the molecule is supercoiled. The linking difference {Delta}Lk = Lk-Lk{sub 0} is partitioned between torsional deformation of the DNA, or twist ({Delta}Tw), and a winding of the DNA axis about itself known as … more
Date: January 1, 1992
Creator: Hunt, N. G.
Partner: UNT Libraries Government Documents Department
open access

Reactivity effects of void formations in a solution critical assembly

Description: SHEBA II (Solution High Energy Burst Assembly) was constructed in order to better understand the neutronics of solutions of fissile materials. In order to estimate the effect on criticality from the formation of bubbles, models were devised in MCNP (Monte Carlo Neutron Photon transport code) and THREEDANT (THREE dimensional, Diffusion-Accelerated, Neutral-Particle Transport). It was found that the formation of voids in all but the outside bottom edge of the assembly cylinder tend to act as a ne… more
Date: January 1, 1994
Creator: Walters, S. G.
Partner: UNT Libraries Government Documents Department
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Strange meson spectroscopy in K{omega} and K{phi} at 11 GeV/c and Cherenkov ring imaging at SLD

Description: This thesis consists of two independent parts; development of Cherenkov Ring Imaging Detector (CRID) system and analysis of high-statistics data of strange meson reactions from the LASS spectrometer. Part 1: The CRID system is devoted to charged particle identification in the SLAC Large Detector (SLD) to study e{sup +}e{sup {minus}} collisions at {radical}s = m{sub Z{sup 0}}. By measuring the angles of emission of the Cherenkov photons inside liquid and gaseous radiators, {pi}/K/p separation wi… more
Date: January 1993
Creator: Kwon, Youngjoon
Partner: UNT Libraries Government Documents Department
open access

Isotopic tracer studies of Fischer-Tropsch Synthesis over Ru/TiO{sub 2} catalysts

Description: Fischer-Tropsch synthesis is a process in which CO and H{sub 2} react to give predominantly liquid hydrocarbons. The reaction can be considered a special type of polymerization in which the monomer is produced in situ, and chain growth occurs by a sequence of independently repeated additions of the monomer to the growing chain. A investigation has been conducted to study the CO hydrogenation reaction in order to better understand catalyst deactivation and the elementary surface processes involv… more
Date: January 1, 1992
Creator: Krishna, K. R.
Partner: UNT Libraries Government Documents Department
open access

Sequence modelling and an extensible data model for genomic database

Description: The Human Genome Project (HGP) plans to sequence the human genome by the beginning of the next century. It will generate DNA sequences of more than 10 billion bases and complex marker sequences (maps) of more than 100 million markers. All of these information will be stored in database management systems (DBMSs). However, existing data models do not have the abstraction mechanism for modelling sequences and existing DBMS`s do not have operations for complex sequences. This work addresses the pr… more
Date: January 1, 1992
Creator: Li, Peter Wei-Der
Partner: UNT Libraries Government Documents Department
open access

Laser: a Tool for Optimization and Enhancement of Analytical Methods

Description: In this work, we use lasers to enhance possibilities of laser desorption methods and to optimize coating procedure for capillary electrophoresis (CE). We use several different instrumental arrangements to characterize matrix-assisted laser desorption (MALD) at atmospheric pressure and in vacuum. In imaging mode, 488-nm argon-ion laser beam is deflected by two acousto-optic deflectors to scan plumes desorbed at atmospheric pressure via absorption. All absorbing species, including neutral molecul… more
Date: January 1, 1997
Creator: Preisler, Jan
Partner: UNT Libraries Government Documents Department
open access

An Experiment in School/Museum/University Collaboration

Description: A thesis submitted by Dr. Jack Davis, Dean and Professor, School of Visual Arts, University of North Texas, and Dr. William McCarter, Regents Professor of Art, School of Visual Arts, University of North Texas, titled "An Experiment in School/Museum/University Collaboration," January 14, 1994. The thesis describes the formation and work of the North Texas Institute for Educators on the Visual Arts, a consortia of six school districts, five museums, two arts councils, two state agencies and the U… more
Date: January 14, 1994
Creator: Davis, Donald Jack & McCarter, William, 1939-
Partner: UNT Libraries Special Collections
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Studies of high temperature ternary phases in mixed-metal-rich early transition metal sulfide and phosphide systems

Description: Investigations of ternary mixed early transition metal-rich sulfide and phosphide systems resulted in the discovery of new structures and new phases. A new series of Zr and Hf - group V transition metal - sulfur K-phases was synthesized and crystallographically characterized. When the group V transition metal was Nb or Ta, the unit cell volume was larger than any previously reported K-phase. The presence of adventitious oxygen was determined in two K-phases through a combination of neutron scat… more
Date: January 4, 1994
Creator: Marking, G. A.
Partner: UNT Libraries Government Documents Department
open access

Studies on the Optimization of Deformation Processed Metal Metal Matrix Composites

Description: A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New… more
Date: January 4, 1994
Creator: Ellis, Tim W.
Partner: UNT Libraries Government Documents Department
open access

Metastable phases in the aluminum-germanium alloy system: Synthesis by mechanical alloying and pressure induced transformations

Description: Al and Ge form a simple equilibrium eutectic with limited mutual solubility and no intermetallic intermediate phases. We used a regular solution approach to model effects of pressure on Al-Ge. Effects of pressure are to extend solubility of Ge in Al, to displace the eutectic composition towards the Ge rich side, and to slightly decrease the eutectic temperature. We designed thermobaric treatments to induce crystal-to-glass transformations in fine grain mixtures of Al and Ge. We used Merrill-Bas… more
Date: January 1, 1994
Creator: Yvon, P.
Partner: UNT Libraries Government Documents Department
open access

The intramolecular cyclization of bis-2,5-dimethylene-2,5-dihydrofurans and bis-2,5-dimethylene-2,5-dihydrothiophenes: An approach to macrocycles

Description: The first two papers of this dissertation present our work with the intramolecular cyclizations of a pair of p-quinodimethanes. The p-quinodimethanes were generated by flash vacuum pyrolysis (FVP) and were linked by a bridging chain. The third paper of this dissertation presents our work in the synthetic manipulation of the products formed from the intramolecular reactions of the p-quinodimethanes.
Date: January 11, 1994
Creator: Klumpp, D. A.
Partner: UNT Libraries Government Documents Department
open access

Solution based synthesis of perovskite-type oxide films and powders

Description: Conventional solid state reactions are diffusion limited processes that require high temperatures and long reaction times to reach completion. In this work, several solution based methods were utilized to circumvent this diffusion limited reaction and achieve product formation at lower temperatures. The solution methods studied all have the common goal of trapping the homogeneity inherent in a solution and transferring this homogeneity to the solid state, thereby creating a solid atomic mixture… more
Date: January 1, 1995
Creator: McHale, J. M. Jr.
Partner: UNT Libraries Government Documents Department
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Comparative plant uptake and microbial degradation of trichloroethylene in the rhizospheres of five plant species-- implications for bioremediation of contaminated surface soils

Description: The objective of this study was to collect data that would provide a foundation for the concept of using vegetation to enhance in situ bioremediation of contaminated surface soils. Soil and vegetation (Lespedeza cuneata, Paspalum notatum, Pinus taeda, and Solidago sp.) samples from the Miscellaneous Chemicals Basin (MCB) at the Savannah River Site were used in tests to identify critical plant and microbiological variables affecting the fate of trichloroethylene (TCE) in the root zone. Microbiol… more
Date: January 1, 1992
Creator: Anderson, T. A. & Walton, B. T.
Partner: UNT Libraries Government Documents Department
open access

A global conformance quality model. A new strategic tool for minimizing defects caused by variation, error, and complexity

Description: The performance of Japanese products in the marketplace points to the dominant role of quality in product competition. Our focus is motivated by the tremendous pressure to improve conformance quality by reducing defects to previously unimaginable limits in the range of 1 to 10 parts per million. Toward this end, we have developed a new model of conformance quality that addresses each of the three principle defect sources: (1) Variation, (2) Human Error, and (3) Complexity. Although the role of … more
Date: January 1, 1994
Creator: Hinckley, C. M.
Partner: UNT Libraries Government Documents Department
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