14 Matching Results

Search Results

Results: 1 - 14
open access

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
open access

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

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
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

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
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
open access

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

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
open access

Development of a low-latency scalar communication routine on message-passing architectures

Description: One of the most significant advances in computer systems over the past decade is parallel processing. To be scalable to a large number of processing nodes and to be able to support multiple levels and forms of parallelism and its flexible use, new parallel machines have to be multicomputer architectures that have general networking support and extremely low internode communication latencies. The performance of a program when ported to a parallel machine is limited mainly by the internode commun… more
Date: January 11, 1994
Creator: Pai, R.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen