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Carbon doping of III-V compound semiconductors

Description: Focus of the study is C acceptor doping of GaAs, since C diffusion coefficient is at least one order of magnitude lower than that of other common p-type dopants in GaAs. C ion implantation results in a concentration of free holes in the valence band < 10% of that of the implanted C atoms for doses > 10{sup 14}/cm{sup 2}. Rutherford backscattering, electrical measurements, Raman spectroscopy, and Fourier transform infrared spectroscopy were amonth the techniques used. Ga co-implantation increase… more
Date: September 1, 1994
Creator: Moll, A. J.
Partner: UNT Libraries Government Documents Department
open access

Laser trapping of {sup 21}Na atoms

Description: This thesis describes an experiment in which about four thousand radioactive {sup 21}Na (t{sub l/2} = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped {sup 21}Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of {sup 21}Na {yields} {sup 21}Ne + {Beta}{sup +} + v{sub e}, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trap… more
Date: September 1, 1994
Creator: Lu, Zheng-Tian
Partner: UNT Libraries Government Documents Department
open access

Analysis of in-situ rock joint strength using digital borehole scanner images

Description: The availability of high resolution digital images of borehole walls using the Borehole Scanner System has made it possible to develop new methods of in-situ rock characterization. This thesis addresses particularly new approaches to the characterization of in-situ joint strength arising from surface roughness. An image processing technique is used to extract the roughness profile from joints in the unrolled image of the borehole wall. A method for estimating in-situ Rengers envelopes using thi… more
Date: September 1, 1994
Creator: Thapa, B. B.
Partner: UNT Libraries Government Documents Department
open access

Straddle-packer determination of the vertical distribution of hydraulic properties in the Snake River Plain Aquifer at well USGS-44, Idaho Chemical Processing Plant, INEL

Description: Many of the monitor wells that penetrate the upper portion of the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL) are open over large intervals that include multiple water-bearing zones. Most of these wells are equipped with dedicated submersible pumps. Water of varying quality from different water-bearing zones is mixed within the wells. The hydrologic properties of individual water bearing zones are difficult to determine. Water quality and water-level data on or… more
Date: September 23, 1994
Creator: Monks, J. I.
Partner: UNT Libraries Government Documents Department
open access

Dependency visualization for complex system understanding

Description: With the volume of software in production use dramatically increasing, the importance of software maintenance has become strikingly apparent. Techniques now sought and developed for reverse engineering and design extraction and recovery. At present, numerous commercial products and research tools exist which are capable of visualizing a variety of programming languages and software constructs. The list of new tools and services continues to grow rapidly. Although the scope of the existing comme… more
Date: September 1, 1994
Creator: Smart, J.A.C.
Partner: UNT Libraries Government Documents Department
open access

Efficient biased random bit generation for parallel processing

Description: A lattice gas automaton was implemented on a massively parallel machine (the BBN TC2000) and a vector supercomputer (the CRAY C90). The automaton models Burgers equation {rho}t + {rho}{rho}{sub x} = {nu}{rho}{sub xx} in 1 dimension. The lattice gas evolves by advecting and colliding pseudo-particles on a 1-dimensional, periodic grid. The specific rules for colliding particles are stochastic in nature and require the generation of many billions of random numbers to create the random bits necessa… more
Date: September 28, 1994
Creator: Slone, D.M.
Partner: UNT Libraries Government Documents Department
open access

Superconducting and normal-state properties of novel materials

Description: Interest in solid state physics naturally gravitates towards novel systems such as the copper oxide superconductors or the alkali-doped fullerenes. This paper tackles high temperature superconductivity by extension of the BCS theory for ordinary superconductors, in particular, incorporation of anharmonicity in phonon dynamics and anisotropy in electron-phonon coupling. These refinements can account for many anomalous properties of the cuprates. Phonon anharmonicity is consistent with a small is… more
Date: September 1, 1994
Creator: Crespi, V.H.
Partner: UNT Libraries Government Documents Department
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