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12th Annual ALS Users' Association Meeting (open access)

12th Annual ALS Users' Association Meeting

Science took the front seat as 219 Advanced Light Source (ALS) users and staff gathered on Monday and Tuesday, October 18 and 19 for the twelfth annual users' meeting. The bulk of the meeting was dedicated to reports on science at the ALS. Packed into two busy days were 31 invited oral presentations and 80 submitted poster presentations, as well as time to visit 24 vendor booths. The oral sessions were dedicated to environmental science, chemical dynamics, biosciences, magnetic materials, and atomic and molecular science. In addition, there was an ALS highlights session that emphasized new results and a session comprising highlights from the young scientists who will carry the ALS into the future.
Date: December 17, 1999
Creator: Robinson, Arthur L.
System: The UNT Digital Library
Reactor-Based Plutonium Disposition: Opportunities, Options, and Issues (open access)

Reactor-Based Plutonium Disposition: Opportunities, Options, and Issues

The end of the Cold War has created a legacy of surplus fissile materials (plutonium and highly enriched uranium) in the United States (U.S.) and the former Soviet Union. These materials pose a danger to national and international security. During the past few years, the U.S. and Russia have engaged in an ongoing dialog concerning the safe storage and disposition of surplus fissile material stockpiles. In January 1997, the Department of Energy (DOE) announced the U. S. would pursue a dual track approach to rendering approximately 50 metric tons of plutonium inaccessible for use in nuclear weapons. One track involves immobilizing the plutonium by combining it with high-level radioactive waste in glass or ceramic ''logs''. The other method, referred to as reactor-based disposition, converts plutonium into mixed oxide (MOX) fuel for nuclear reactors. The U.S. and Russia are moving ahead rapidly to develop and demonstrate the technology required to implement the MOX option in their respective countries. U.S. MOX fuel research and development activities were started in the 1950s, with irradiation of MOX fuel rods in commercial light water reactors (LWR) from the 1960s--1980s. In all, a few thousand MOX fuel rods were successfully irradiated. Though much of this work …
Date: July 17, 1999
Creator: Greene, S. R.
System: The UNT Digital Library
Performance Study of Scepter<sup>TM</sup> Metal Bond Diamond Grinding Wheel (open access)

Performance Study of Scepter<sup>TM</sup> Metal Bond Diamond Grinding Wheel

Advanced ceramics are attractive for many applications in the transportation, energy, military, and industrial markets because they possess properties of high-temperature durability, corrosion resistance, strength, hardness, stiffness, and wear resistance. Unfortunately, these same properties make advanced ceramics more difficult to machine than traditional materials. The reliability and manufacturing costs of advanced ceramic components are significant concerns that must be overcome. Nevertheless, the use of advanced ceramic materials is expected to increase dramatically in new transportation systems in response to more stringent energy conservation and pollution reduction requirements. This study discusses the goals, commercialization plans, phased development, scale-up, testing, and external verification of performance of the innovative grinding wheel that evolved from the project.
Date: June 17, 1999
Creator: Denison, S. K.; Licht, R. W.; McSpadden Jr., S. B.; Parten, R. J.; Picone, J. W. & Shelton, J. E.
System: The UNT Digital Library
CP Violation in B Decays at the Tevatron (open access)

CP Violation in B Decays at the Tevatron

Between 1992 to 1996, the CDF and D0 detectors each collected data samples exceeding 100 pb{sup {minus}1} of p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. These data sets led to a large number of precision measurements of the properties of B hadrons including lifetimes, masses, neutral B meson flavor oscillations, and relative branching fractions, and to the discovery of the B{sub 0} meson. Perhaps the most exciting result was the first look at the CP violation parameter sin ({vert_bar}2{beta}){vert_bar} using the world's largest sample of fully reconstructed B{sup 0}/{bar B}{sup 0} {r_arrow} J/{psi}K{sub s}{sup 0} decays. A summary of this result is presented here. In the year 2000, the Tevatron will recommence p{bar p} collisions with an over order of magnitude expected increased in integrated luminosity (1 fb{sup {minus}1} per year). The CDF and D0 detectors will have undergone substantial upgrades, particularly in the tracking detectors and the triggers. With these enhancements, the Tevatron B physics program includes precision measurements of sin(2{beta}) and B{sub s}{sup 0} flavor oscillations, as well as studies of rare B decays that are sensitive to new physics. The studies of B{sub s}{sup 0} mesons will be particularly interesting as this …
Date: September 17, 1999
Creator: Kroll, I. Joseph
System: The UNT Digital Library
Validating the role of AFVs in voluntary mobile source emission reduction programs. (open access)

Validating the role of AFVs in voluntary mobile source emission reduction programs.

Late in 1997, EPA announced new allowances for voluntary emission control programs. As a result, the US Department of Energy's (DOE) Clean Cities and other metro areas that have made an ongoing commitment to increasing participation by alternative fuel vehicles (AFVs) in local fleets have the opportunity to estimate the magnitude and obtain emission reduction credit for following through on that commitment. Unexpectedly large reductions in key ozone precursor emissions in key locations and times of the day can be achieved per vehicle-mile by selecting specific light duty AFV offerings from original equipment manufacturers (OEMs) in lieu of their gasoline-fueled counterparts. Additional benefit accrues from the fact that evaporative emissions of non-methane hydrocarbons (generated in the case of CNG, LNG, and LPG by closed fuel-system AFV technology) can be essentially negligible. Upstream emissions from fuel storage and distribution with the airshed of interest are also reduced. This paper provides a justification and outlines a method for including AFVs in the mix of strategies to achieve local and regional improvements in ozone air quality, and for quantifying emission reduction credits. At the time of submission of this paper, the method was still under review by the US EPA Office of Mobile …
Date: March 17, 1999
Creator: Santini, D. J. & Saricks, C. L.
System: The UNT Digital Library
Stress Voiding in IC Interconnects - Rules of Evidence for Failure Analysts (open access)

Stress Voiding in IC Interconnects - Rules of Evidence for Failure Analysts

Mention the words ''stress voiding'', and everyone from technology engineer to manager to customer is likely to cringe. This IC failure mechanism elicits fear because it is insidious, capricious, and difficult to identify and arrest. There are reasons to believe that a damascene-copper future might be void-free. Nevertheless, engineers who continue to produce ICs with Al-alloy interconnects, or who assess the reliability of legacy ICs with long service life, need up-to-date insights and techniques to deal with stress voiding problems. Stress voiding need not be fearful. Not always predictable, neither is it inevitable. On the contrary, stress voids are caused by specific, avoidable processing errors. Analytical work, though often painful, can identify these errors when stress voiding occurs, and vigilance in monitoring the improved process can keep it from recurring. In this article, they show that a methodical, forensics approach to failure analysis can solve suspected cases of stress voiding. This approach uses new techniques, and patiently applies familiar ones, to develop evidence meeting strict standards of proof.
Date: September 17, 1999
Creator: FILTER, WILLIAM F.
System: The UNT Digital Library
Decay heat removal by natural convection - the RVACS system. (open access)

Decay heat removal by natural convection - the RVACS system.

In conclusion, this work shows that for sodium coolant the reactor vessel auxiliary cooling system (RVACS) is an effective passive heat removal system if the reactor power does not exceed about 1600 MW(th). Its effectiveness is limited by the effective radiative heat transfer coefficient in the inner gap. In a lead cooled system, economic considerations may impose a lower limit.
Date: August 17, 1999
Creator: Tzanos, C. P.
System: The UNT Digital Library
Terascale spectral element algorithms and implementations. (open access)

Terascale spectral element algorithms and implementations.

We describe the development and implementation of an efficient spectral element code for multimillion gridpoint simulations of incompressible flows in general two- and three-dimensional domains. We review basic and recently developed algorithmic underpinnings that have resulted in good parallel and vector performance on a broad range of architectures, including the terascale computing systems now coming online at the DOE labs. Sustained performance of 219 GFLOPS has been recently achieved on 2048 nodes of the Intel ASCI-Red machine at Sandia.
Date: August 17, 1999
Creator: Fischer, P. F. & Tufo, H. M.
System: The UNT Digital Library
What's in your bookmark? Green building information on the Web. (open access)

What's in your bookmark? Green building information on the Web.

In listing web sites that are of special interest to the Affordable Comfort community, we will try to categorize sites in six major areas: Green Building Product Directories, Software Tools on the Web, Good Places for Learning, Health and Indoor Environment Information, Important Discussion Groups and E-mail Lists, and Sites of Sites. Since we can not help but leave out a great deal, we invite the reader to contact us for lists of sites that we could not include.
Date: February 17, 1999
Creator: Cavallo, J. D. & Iversen, M. R.
System: The UNT Digital Library
Fluoro-Carbonate Solvents for Li-Ion Cells (open access)

Fluoro-Carbonate Solvents for Li-Ion Cells

A number of fluoro-carbonate solvents were evaluated as electrolytes for Li-ion cells. These solvents are fluorine analogs of the conventional electrolyte solvents such as dimethyl carbonate, ethylene carbonate, diethyl carbonate in Li-ion cells. Conductivity of single and mixed fluoro carbonate electrolytes containing 1 M LiPF{sub 6} was measured at different temperatures. These electrolytes did not freeze at -40 C. We are evaluating currently, the irreversible 1st cycle capacity loss in carbon anode in these electrolytes and the capacity loss will be compared to that in the conventional electrolytes. Voltage stability windows of the electrolytes were measured at room temperature and compared with that of the conventional electrolytes. The fluoro-carbon electrolytes appear to be more stable than the conventional electrolytes near Li voltage. Few preliminary electrochemical data of the fluoro-carbonate solvents in full cells are reported in the literature. For example, some of the fluorocarbonate solvents appear to have a wider voltage window than the conventional electrolyte solvents. For example, methyl 2,2,2 trifluoro ethyl carbonate containing 1 M LiPF{sub 6} electrolyte has a decomposition voltage exceeding 6 V vs. Li compared to &lt;5 V for conventional electrolytes. The solvent also appears to be stable in contact with lithium at room temperature.
Date: September 17, 1999
Creator: Nagasubramanian, Ganesan
System: The UNT Digital Library
Measuring explosive non-ideality (open access)

Measuring explosive non-ideality

The sonic reaction zone length may be measured by four methods: (1) size effect, (2) detonation front curvature, (3) crystal interface velocity and (4) in-situ gauges. The amount of data decreases exponentially from (1) to (4) with there being almost no gauge data for prompt detonation at steady state. The ease and clarity of obtaining the reaction zone length increases from (1) to (4). The method of getting the reaction zone length, &lt;x{sub e}&gt;, is described for the four methods. A measure of non-ideality is proposed: the reaction zone length divided by the cylinder radius. N = &lt;x{sub e}&gt;/R{sub o}. N = 0 for true ideality. It also decreases with increasing radius as it should. For N &lt; 0.10, an equilibrium EOS like the JWL may be used. For N &gt; 0.10, a time-dependent description is essential. The crystal experiment, which measures the particle velocity of an explosive-transparent material interface, is presently rising in importance. We examine the data from three experiments and apply: (1) an impedance correction that transfers the explosive C-J particle velocity to the corresponding value for the interface, and (2) multiplies the interface time by 3/4 to simulate the explosive speed of sound. The result is …
Date: February 17, 1999
Creator: Souers, P C
System: The UNT Digital Library
Thermal Stability of Li-Ion Cells (open access)

Thermal Stability of Li-Ion Cells

The thermal stability of Li-ion cells with intercalating carbon anodes and metal oxide cathodes was measured as a function of state of charge and temperature for two advanced cell chemistries. Cells of the 18650 design with Li{sub x}CoO{sub 2} cathodes (commercial SONY cells) and Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2} cathodes were measured for thermal reactivity in the open circuit cell condition. Accelerating rate calorimetry (ARC) was used to measure cell thermal runaway as a function of state of charge (SOC). Microcalorimetry was used to measure the time dependence of heat generating side reactions also as a function of SOC. Components of cells were measured using differential scanning calorimetry (DSC) to study the thermal reactivity of the individual electrodes to determine the temperature regimes and conditions of the major thermal reactions. Thermal decomposition of the SEI layer at the anodes was identified as the initiating source for thermal runaway. The cells with Li{sub x}CoO{sub 2} cathodes showed greater sensitivity to SOC and higher accelerating heating rates than seen for the cells with Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2}cathodes. Lower temperature reactions starting as low as 40 C were also observed that were SOC dependent but not accelerating. These reactions were also measured …
Date: September 17, 1999
Creator: ROTH,EMANUEL P.
System: The UNT Digital Library
ORIGEN-ARP, A Fast and Easy-to-Use Source Term Generation Tool (open access)

ORIGEN-ARP, A Fast and Easy-to-Use Source Term Generation Tool

ORIGEN-ARP is a new SCALE analytical sequence for spent fuel characterization and source term generation that serves as a faster alternative to the SAS2H sequence by using the Automatic Rapid Processing (ARP) methodology for generating problem-dependent ORIGEN-S cross-section libraries. ORIGEN-ARP provides an easy-to-use menu-driven input processor. This new sequence is two orders of magnitude faster than SAS2H while conserving the rigor and accuracy of the SAS2H methodology. ORIGEN-ARP has been validated against pressurized water reactor (PWR) and boiling water reactor (BWR) spent fuel chemical assay data.
Date: October 17, 1999
Creator: Bowman, S.M.; Hermann, O.W.; Leal, L.C. & Parks, C.V.
System: The UNT Digital Library
Shielding Experimental Benchmark Storage, Retrieval, and Display System (open access)

Shielding Experimental Benchmark Storage, Retrieval, and Display System

The complete description of an integral shielding benchmark experiment includes the radiation source, materials, physical geometry, and measurement data. This information is not usually contained in a single document, but must be gathered from several sources, including personal contact with the experimentalists. A comprehensive database of the experimental details is extremely useful and cost-effective in present day computations. Further, experimental data are vulnerable to being lost or destroyed as a result of facility closures, retirement of experimental personnel, and ignorance. A standard set of experiments, used globally, establishes a framework to validate and verify models in computer codes and guarantee comparative analyses between different computational systems. SINBAD is a database that was conceived in 1992 to store, retrieve, and display the measurements from international experiments for the past 50 years in nuclear shielding. Based at Oak Ridge National Laboratory's Radiation Safety Information and Computational Center (RSICC) SINBAD has a collection of integral benchmark experiments from around the world. SINBAD is shared with the Office of Economic and Cooperative Development/Nuclear Energy Agency Data Bank, which provides contributions from Europe, Russia, and Japan.
Date: October 17, 1999
Creator: Hunter, H.; Kodeli, I.; Marshall, W. J.; Parson, J. & Sartor, E.
System: The UNT Digital Library
In-Situ Chemical Dynamics and Phase Mapping Under Steep Thermal Gradients Using Time-Resolved and Spatially Resolved X-Ray Diffraction (open access)

In-Situ Chemical Dynamics and Phase Mapping Under Steep Thermal Gradients Using Time-Resolved and Spatially Resolved X-Ray Diffraction

Time-resolved and spatially-resolved diffraction techniques have been developed recently to perform materials dynamics study in-situ extending into the time and spatial domain in high temperature processes. The applications of these methods to investigate the chemical dynamics of solid combustion reactions and to map phases and their transformation in fusion welds are exemplified in this paper.
Date: September 17, 1999
Creator: Wong, J.; Larson, E.M.; Holt, J.B.; Ressler, T. & Elmer, J.W.
System: The UNT Digital Library
Stress Corrosion Crack Detection on HU-25 Guardian Aircraft (open access)

Stress Corrosion Crack Detection on HU-25 Guardian Aircraft

Several ultrasonic inspection methods were developed at the Federal Aviation Administration's Airworthiness Assurance NDI Validation Center (AANC) to easily and rapidly detect hidden stress corrosion cracks in all vertical windshield posts on the US Coast Guard (USCG) HU-25 Guardian aircraft. The inspection procedure locates cracks as small as 2.0 millimeters emanating from internal fastener holes and determines their length. A test procedure was developed and a baseline assessment of the USCG fleet was conducted. Inspection results on twenty-five aircraft revealed a good correlation with results made during subsequent structural disassembly and visual inspection.
Date: February 17, 1999
Creator: Blackmon, R.; Huffman, J.; Mello, C.W.; Moore, D.G. & Walkington, P.D.
System: The UNT Digital Library
Applications of Solar Technology for Catastrophe Response, Claims Management, and Loss Prevention (open access)

Applications of Solar Technology for Catastrophe Response, Claims Management, and Loss Prevention

Today's insurance industry strongly emphasizes developing cost-effective hazard mitigation programs, increasing and retaining commercial and residential customers through better service, educating customers on their exposure and vulnerabilities to natural disasters, collaborating with government agencies and emergency management organizations, and exploring the use of new technologies to reduce the financial impact of disasters. In June of 1998, the National Renewable Energy Laboratory (NREL) and the National Association of Independent Insurers (NAII) sponsored a seminar titled, ''Solar Technology and the Insurance Industry.'' Presentations were made by insurance company representatives, insurance trade groups, government and state emergency management organizations, and technology specialists. The meeting was attended by insurers, brokers, emergency managers, and consultants from more than 25 US companies. Leading insurers from the personal line and commercial carriers were shown how solar technology can be used in underwriting, claims, catastrophe response, loss control, and risk management. Attendees requested a follow-up report on solar technology, cost, and applications in disasters, including suggestions on how to collaborate with the utility industry and how to develop educational programs for business and consumers. This report will address these issues, with an emphasis on pre-disaster planning and mitigation alternatives. It will also discuss how energy efficiency and renewable …
Date: February 17, 1999
Creator: Deering, A. & Thornton, J.P.
System: The UNT Digital Library
High-Density Plasma Etching of Group-III Nitride Films for Device Application (open access)

High-Density Plasma Etching of Group-III Nitride Films for Device Application

As III-V nitride device structures become more complicated and design rules shrink, well-controlled etch processes are necessary. Due to limited wet chemical etch results for the group-III nitrides, a significant amount of effort has been devoted to the development of dry etch processing. Dry etch development was initially focused on mesa structures where high etch rates, anisotropic profiles, smooth sidewalls, and equi-rate etching of dissimilar materials were required. For example, commercially available LEDs and laser facets for GaN-based laser diodes have been patterned using reactive ion etching (RIE). With the recent interest in high power, high temperature electronic devices, etch characteristics may also require smooth surface morphology, low plasma-induced damage, and selective etching of one layer over another. The principal criteria for any plasma etch process is its utility in the fabrication of a device. In this study, we will report plasma etch results for the group-III nitrides and their application to device structures.
Date: February 17, 1999
Creator: Baca, A. G.; Crawford, M. H.; Han, J.; Lester, L. F.; Pearton, S. J.; Ren, F. et al.
System: The UNT Digital Library
Seismic studies of the San Francisco-Oakland Bay Bridge (open access)

Seismic studies of the San Francisco-Oakland Bay Bridge

Computational simulation plays a central role in the engineering analysis and design of major bridge structures and accurate simulations are essential for the development of earthquake resistant and economical structural designs. This paper describes new methodologies and computational tools which have recently been developed for simulating earthquake ground motions and the seismic response of cable supported bridges. The simulation tools are described and an example application for an important long-span suspension bridge is demonstrated. The application portion of the study has particular focus on the potential damaging effects of long period displacement pulses and permanent ground displacements which can occur when a bridge is located in the near-field of a major earthquake fault.
Date: August 17, 1999
Creator: Astaneh-Asl, A.; Larsen, S. & McCallen, D.
System: The UNT Digital Library
Target experimental area and systems of the U.S. National Ignition Facility (open access)

Target experimental area and systems of the U.S. National Ignition Facility

One of the major goals of the US National Ignition Facility is the demonstration of laser driven fusion ignition and burn of targets by inertial confinement and provide capability for a wide variety of high energy density physics experiments. The NIF target area houses the optical systems required to focus the 192 beamlets to a target precisely positioned at the center of the 10 meter diameter, 10-cm thick aluminum target chamber. The chamber serves as mounting surface for the 48 final optics assemblies, the target alignment and positioning equipment, and the target diagnostics. The internal surfaces of the chamber are protected by louvered steel beam dumps. The target area also provides the necessary shielding against target emission and environmental protection equipment. Despite its complexity, the design provides the flexibility to accommodate the needs of the various NIF user groups, such as direct and indirect drive irradiation geometries, modular final optics design, capability to handle cryogenic targets, and easily re-configurable diagnostic instruments. Efficient target area operations are ensured by using line-replaceable designs for systems requiring frequent inspection, maintenance and reconfiguration, such as the final optics, debris shields, phase plates and the diagnostic instruments. A precision diagnostic instrument manipulator (DIMS) allows fast …
Date: December 17, 1999
Creator: Tobin, M.; Van Wonterghem, B.; MacGowan, B. J.; Hibbard, W.; Kalantar, D.; Lee, F. D. et al.
System: The UNT Digital Library
Theoretical developments in inclusive B decays (open access)

Theoretical developments in inclusive B decays

Some recent theoretical work on inclusive B decays relevant for the model independent determination of {vert_bar}V{sub ub}{vert_bar} and {vert_bar}V{sub cb}{vert_bar} is summarized. The theoretical predictions and their reliability for several differential decay distributions in {anti B}{yields}X{sub c,u}e{anti {nu}} and {anti B}{yields}X{sub s}{gamma} are reviewed. These can be used to determine certain important HQET matrix elements. The upsilon expansion and ways of testing it are discussed.
Date: May 17, 1999
Creator: Ligeti, Zoltan
System: The UNT Digital Library
Nuclear Science at GEANIE (open access)

Nuclear Science at GEANIE

GEANIE at LANSCE/WNR combines the precision energy resolution of germanium detectors with the advantages of a white source providing neutrons with energies 1 &lt; E{sub n}(MeV) &lt; 250 to address a variety of topics in nuclear physics. The authors present the analysis of two data sets, n+{sup 235}U and n+{sup 92}Mo, acquired at GEANIE during the 1998 beam cycle. These data showcase the breadth of subjects under study at this facility, including the spectroscopy of stable and near-stable nuclei, reaction dynamics, fission studies, and the relative population of isomer and ground states in neutron-induced reactions.
Date: December 17, 1999
Creator: Younes, W.; Becker, J. A.; Bernstein, L. A.; Garrett, P. E.; McNabb, D. P.; McGrath, C. A. et al.
System: The UNT Digital Library
Selective depredation of planted hardwood seedlings by wild pigs in a wetland restoration area (open access)

Selective depredation of planted hardwood seedlings by wild pigs in a wetland restoration area

Following the planting of several thousand hardwood seedlings in a 69-ha wetland restoration area in west-central South Carolina, wild pigs (Sus scrofa) depredated a large percentage of the young trees. This planting was undertaken as part of a mitigation effort to restore a bottomland hardwood community in the corridor and delta of a third order stream that had been previously impacted by the discharge of heated nuclear reactor effluent. The depredated restoration areas had been pretreated with both herbicide and control burning prior to planting the hardwood seedlings. After discovery of the wild pig damage, these areas were surveyed on foot to assess the magnitude of the depredation on the planted seedling crop. Foraging by the local wild pigs in the pretreatment areas selectively impacted only four of the nine hardwood species used in this restoration effort. Based on the surveys, the remaining five species did not appear to have been impacted at all. A variety of reasons could be used to explain this phenomenon. The pretreatment methodology is thought to have been the primary aspect of the restoration program that initially led the wild pigs to discover the planted seedlings. In addition, it is possible that a combination of …
Date: December 17, 1999
Creator: Mayer, J.J.
System: The UNT Digital Library
Measuring Property Management Risk and Loss: Step One Toward Managing Property on a Foundation of Risk, Cost, and Benefit (open access)

Measuring Property Management Risk and Loss: Step One Toward Managing Property on a Foundation of Risk, Cost, and Benefit

This is a period of ever-tightening defense budgets and continuing pressure on the public sector to be more commercial-like, Property policies, practices, and regulations are increasingly being challenged and changed. In these times, we must be leaders in understanding and defining the value of our profession from a commercial standpoint so that we can provide the right services to our customers and explain and defend the value of those services. To do so, we must step outside current property management practices, regulations, and oversight. We must learn to think and speak in the language of those who fund us--a financial language of risk, cost, and benefit. Regardless of regulation and oversight, our bosses are demanding that we demonstrate (financially) the benefits of current practice, or else. This article is intended to be the beginning of an effort to understand and define our profession in terms of risk, cost, and benefit so that we can meet these new challenges. The first step in this effort must be defining and measuring risk, cost, and benefit. Our costs, although sometimes difficult to capture, are easy to understand: they are almost exclusively the effort, both within and without the property management organization, involved in …
Date: May 17, 1999
Creator: Johnson, Curtis
System: The UNT Digital Library