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MACHO project 9 million star color-magnitude diagram of the large magellanic cloud
The authors present a 9 million star color-magnitude diagram (9M CMD) of the Large Magellanic Cloud (LMC) bar. The 9M CMD reveals a complex superposition of different age and metallicity stellar populations, with important stellar evolutionary phases occurring over three orders of magnitude in number density. First, they count the non-variable red and blue supergiants, the associated Cepheid variables, and measure the stellar effective temperatures defining the Cepheid instability strip. Lifetime predictions of stellar evolution theory are tested, with implications for the origin of low-luminosity Cepheids. The highly-evolved asymptotic giant branch (AGB) stars in the 9M CMD have a bimodal distribution in brightness, which they interpret as discrete old populations ({ge} 1 Gyr). The faint AGB sequence may be metal-poor and very old. Comparing the mean properties of giant branch and horizontal branch (HB) stars in the 9M CMD to those of clusters, they identify NGC 411 and M3 as templates for the admixture of old stellar populations in the bar. However, there are several indications that the old and metal-poor field population has a red HB morphology: the RR Lyrae variables lie preferentially on the red edge of the instability strip, the AGB-bump is very red, and the ratio …
Date:
January 31, 2000
Creator:
Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Basu, A.; Becker, A. C. et al.
Object Type:
Report
System:
The UNT Digital Library
A Hybrid Hydrologic-Geophysical Inverse Technique For The Assessment And Monitoring Of Leachates In The Vadose Zone
At many DOE facilities, the presence of radioactive wastes and other contaminants within the vadose zone poses a serious and ongoing threat to public health and safety. In many cases these contaminants have been introduced directly to the vadose zone through releases on the surface or in shallow pits, and through leaking storage facilities. To reduce the environmental risks these wastes pose, the DOE is currently considering two fundamentally different approaches. The first involves remediation by treating contaminants in-place while the second, and more economically feasible being examined by DOE, involves in-situ immobilization of the wastes. Immobilization would be achieved through both injection of subsurface grout barriers to block transport pathways and installation of surface caps to prevent additional water infiltration into contaminated formations. A necessary requirement of both remediation approaches is the need to obtain information on the spatial distributions of the hydraulic and transport properties, the amount of contamination in place, and flow and transport processes that are occurring. With this information in hand, informed decisions can be made in order to optimize the remediation process for each particular case. In particular, these capabilities could result in reduced remediation costs, as well as providing necessary data to illustrate …
Date:
December 31, 2000
Creator:
Alumbaugh, David L.
Object Type:
Report
System:
The UNT Digital Library
LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES
This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and Testing of Planar Single Cells. During this time period substantial progress has been made in developing low temperature deposition techniques to produce dense, nanocrystalline yttrium-stabilized zirconia films on both dense oxide and polymer substrates. Progress has been made in the preparation and characterization of thin electrolytes and porous LSM substrates. Both of these tasks are essentially on or ahead of schedule. In our proposal, we suggested that the ZrO{sub 2}/Sc system needed to be considered as a candidate as a thin electrolyte. This was because microcrystalline ZrO{sub 2}/Sc has a significantly higher ionic conductivity than YSZ, particularly at the lower temperatures. As a result, some 0.5 micron thick film of ZrO{sub 2}/16% Sc on an alumina substrate (grain size 20nm) was prepared and the electrical conductivity measured as a function of temperature and oxygen activity. The Sc doped ZrO{sub 2} certainly has a higher conductivity that either 20nm or 2400nm YSZ, however, electronic conductivity dominates the conductivity for oxygen activities below 10{sup -15}. Whereas for YSZ, electronic conductivity is not a problem until the oxygen activity decreases below 10{sup -25}. These …
Date:
March 31, 2000
Creator:
Anderson, Harlan U.
Object Type:
Report
System:
The UNT Digital Library
Recovery of Valuable Chlorosilane Intermediates by a Novel Waste Conversion Process, Phase IIIB (Progress)
From June 1998 through September 1999, direct process residue (DPR, a waste byproduct) hydrogenolysis has been studied at a large pilot plant within Dow Corning's Carrollton, KY, facility. The system reacts filtered DPR with chlorosilane monomers at high temperature and pressure. The process routinely demonstrates DPR conversions from 59% to 89% on a monthly basis. The reaction product contains high concentrations of valuable monomers such as dimethyldichlorosilane and methyldichlorosilane. An expansion of the current unit's capacity is planned to be on-line by the end of CY2000. Furthermore, a larger DPR hydrogenolysis reactor based on these results is being designed for operation in Europe at Dow Corning's Barry, Wales, site.
Date:
March 31, 2000
Creator:
Anderson, Kurt E.
Object Type:
Report
System:
The UNT Digital Library
The Mailbox Computer System for the IAEA verification experiment on HEU downlending at the Portsmouth Gaseous Diffusion Plant
IN APRIL 1996, THE UNITED STATES (US) ADDED THE PORTSMOUTH GASEOUS DIFFUSION PLANT TO THE LIST OF FACILITIES ELIGIBLE FOR THE APPLICATION OF INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) SAFEGUARDS. AT THAT TIME, THE US PROPOSED THAT THE IAEA CARRY OUT A ''VERIFICATION EXPERIMENT'' AT THE PLANT WITH RESPECT TO DOOWNBLENDING OF ABOUT 13 METRIC TONS OF HIGHLY ENRICHED URANIUM (HEU) IN THE FORM OF URANIUM HEXAFLUROIDE (UF6). DURING THE PERIOD DECEMBER 1997 THROUGH JULY 1998, THE IAEA CARRIED OUT THE REQUESTED VERIFICATION EXPERIMENT. THE VERIFICATION APPROACH USED FOR THIS EXPERIMENT INCLUDED, AMONG OTHER MEASURES, THE ENTRY OF PROCESS-OPERATIONAL DATA BY THE FACILITY OPERATOR ON A NEAR-REAL-TIME BASIS INTO A ''MAILBOX'' COMPUTER LOCATED WITHIN A TAMPER-INDICATING ENCLOSURE SEALED BY THE IAEA.
Date:
July 31, 2000
Creator:
Aronson, Arnold L. & Gordon, David M.
Object Type:
Report
System:
The UNT Digital Library
Low-Dislocation-Density GaN from a Single Growth on a Textured Substrate
The density of threading dislocations (TD) in GaN grown directly on flat sapphire substrates is typically greater than 10{sup 9}/cm{sup 2}. Such high dislocation densities degrade both the electronic and photonic properties of the material. The density of dislocations can be decreased by orders of magnitude using cantilever epitaxy (CE), which employs prepatterned sapphire substrates to provide reduced-dimension mesa regions for nucleation and etched trenches between them for suspended lateral growth of GaN or AlGaN. The substrate is prepatterned with narrow lines and etched to a depth that permits coalescence of laterally growing III-N nucleated on the mesa surfaces before vertical growth fills the etched trench. Low dislocation densities typical of epitaxial lateral overgrowth (ELO) are obtained in the cantilever regions and the TD density is also reduced up to 1 micrometer from the edge of the support regions.
Date:
July 31, 2000
Creator:
Ashby, Carol I.; Willan, Christine C.; Han, Jung; Missert, Nancy A.; Provencio, Paula P.; Follstaedt, David M. et al.
Object Type:
Article
System:
The UNT Digital Library
Chemical Conversion of TNT: Production of 2,4,6-Trinitrobenzoic Acid
Oxidation of 2,4,6-trinitrotoluene (TNT) by aqueous nitric acid at high temperature and pressure gives 2,4,6-trinitrobenzoic acid (TNBA) and other valuable products, such as 1,3,5-trinitrobenzene (TNB). Optimization of the kinetics proved to be critical for the selective oxidation of the methyl group. High yield of a desired product can be obtained only under a narrow range of conditions. Thus, the best yield (70 to 75%) of TNBA was achieved at a 35 to 45% conversion of TNT (80% nitric acid, 194 C, 20 min), whereas the decarboxylation product (TNB) was the major component of the reaction mixture after a 50-min reaction. Subsequent separation of TNBA was achieved by selective extraction with aqueous bicarbonate. Practical technology development steps for a continuous mode of operation leading to the chief products are also discussed. This technology can use commercial raw trotyl and trotyl from discharged ammunition as the starting material. The latter could be of particular importance for the conversion program aimed at the utilization of ammunition supplies.
Date:
August 31, 2000
Creator:
Astrat'ev, A.A.
Object Type:
Report
System:
The UNT Digital Library
ADVANCED SORBENT DEVELOPMENT PROGRAM DEVELOPMENT OF SORBENTS FOR MOVING-BED AND FLUIDIZED-BED APPLICATIONS
The integrated gasification combined cycle (IGCC) power system using high-temperature coal gas cleanup is one of the most promising advanced technologies for the production of electric power from coal in an environmentally acceptable manner. Unlike conventional low-temperature cleanup systems that require costly heat exchangers, high-temperature coal gas cleanup systems can be operated near 482-538 C (900-1000 F) or higher, conditions that are a closer match with the gasifier and turbine components in the IGCC system, thus resulting is a more efficient overall system. GE is developing a moving-bed, high-temperature desulfurization system for the IGCC power cycle in which zinc-based regenerable sorbents are currently being used as desulfurization sorbents. Zinc titanate and other proprietary zinc-based oxides are being considered as sorbents for use in the Clean Coal Technology Demonstration Program at Tampa Electric Co.'s (TECo) Polk Power Station. Under cold startup conditions at TECo, desulfurization and regeneration may be carried out at temperatures as low as 343 C (650 F), hence a versatile sorbent is desirable to perform over this wide temperature range. A key to success in the development of high-temperature desulfurization systems is the matching of sorbent properties for the selected process operating conditions, namely, sustainable desulfurization kinetics, high …
Date:
March 31, 2000
Creator:
Ayala, R.E; Venkataramani, V.S.; Abbasian, Javad; Slimane, Rachid B.; Williams, Brett E.; Zarnegar, Minoo K. et al.
Object Type:
Report
System:
The UNT Digital Library
Preliminary Closure Plan for the Immobilized Low Activity Waste (ILAW) Disposal Facility
This document describes the preliminary plans for closure of the Immobilized Low-Activity Waste (ILAW) disposal facility to be built by the Office of River Protection at the Hanford site in southeastern Washington. The facility will provide near-surface disposal of up to 204,000 cubic meters of ILAW in engineered trenches with modified RCRA Subtitle C closure barriers.
Date:
August 31, 2000
Creator:
BURBANK, D.A.
Object Type:
Report
System:
The UNT Digital Library
IFSAR for the Rapid Terrain Visualization Demonstration
The Rapid Terrain Visualization Advanced Concept Technology Demonstration (RTV-ACTD) is designed to demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies. The primary sensor for this mission is an interferometric synthetic aperture radar (IFSAR) designed at Sandia National Laboratories. This paper will outline the design of the system and its performance, and show some recent flight test results. The RTV IFSAR will meet DTED level III and IV specifications by using a multiple-baseline design and high-accuracy differential and carrier-phase GPS navigation. It includes innovative near-real-time DEM production on-board the aircraft. The system is being flown on a deHavilland DHC-7 Army aircraft.
Date:
October 31, 2000
Creator:
BURNS,BRYAN L.; EICHEL,PAUL H.; HENSLEY JR.,WILLIAM H. & KIM,THEODORE J.
Object Type:
Article
System:
The UNT Digital Library
Today Cedar Hill (Duncanville, Tex.), Vol. 35, No. 23, Ed. 1 Thursday, August 31, 2000
Weekly newspaper published in Duncanville, Texas that includes local Cedar Hill, state, and national news along with advertising.
Date:
August 31, 2000
Creator:
Balentine, Kevin
Object Type:
Newspaper
System:
The Portal to Texas History
Solid Waste Integrated Forecast Technical (SWIFT) Report FY2001 to FY2046 Volume 1
This report provides up-to-date life cycle information about the radioactive solid waste expected to be managed by Hanford's Waste Management (WM) Project from onsite and offsite generators. It includes: an overview of Hanford-wide solid waste to be managed by the WM Project; program-level and waste class-specific estimates; background information on waste sources; and comparisons to previous forecasts and other national data sources. This report does not include: waste to be managed by the Environmental Restoration (EM-40) contractor (i.e., waste that will be disposed of at the Environmental Restoration Disposal Facility (ERDF)); waste that has been received by the WM Project to date (i.e., inventory waste); mixed low-level waste that will be processed and disposed by the River Protection Program; and liquid waste (current or future generation). Although this report currently does not include liquid wastes, they may be added as information becomes available.
Date:
August 31, 2000
Creator:
Barcot, R. A.
Object Type:
Report
System:
The UNT Digital Library
News Bulletin (Castroville, Tex.), Vol. 42, No. 35, Ed. 1 Thursday, August 31, 2000
Weekly newspaper from Castroville, Texas that includes local, state, and national news along with extensive advertising.
Date:
August 31, 2000
Creator:
Barnes, Thomas
Object Type:
Newspaper
System:
The Portal to Texas History
Groundwater Monitoring and Tritium-Tracking Plan for the 200 Area State-Approved Land Disposal Site
The 200 Area State-Approved Land Disposal Site (SALDS) is a drainfield which receives treated wastewater, occasionally containing high levels of tritium from treatment of Hanford Site liquid wastes. Only the SALDS proximal wells (699-48-77A, 699-48-77C, and 699-48-77D) have been affected by tritium from the facility thus far; the highest activity observed (2.1E+6 pCi/L) occurred in well 699-48-77D in February 1998. Analytical results of groundwater geochemistry since groundwater monitoring began at the SALDS indicate that all constituents with permit enforcement limits have been below those limits with the exception of one measurement of total dissolved solids (TDS) in 1996. The revised groundwater monitoring sampling and analysis plan eliminates chloroform, acetone, tetrahydrofuran, benzene, and ammonia as constituents. Replicate field measurements will replace laboratory measurements of pH for compliance purposes. A deep companion well to well 699-51-75 will be monitored for tritium deeper in the uppermost aquifer.
Date:
August 31, 2000
Creator:
Barnett, D. Brent
Object Type:
Report
System:
The UNT Digital Library
Groundwater Monitoring and Tritium-Tracking Plan for the 200 Area State-Approved Land Disposal Site
The 200 Area State-Approved Land Disposal Site (SALDS) is a drainfield which receives treated wastewater, occasionally containing tritium from treatment of Hanford Site liquid wastes at the 200 Area Effluent Treatment Facility (ETF). Since operation of the SALDS began in December 1995, discharges of tritium have totaled {approx}304 Ci, only half of what was originally predicted for tritium quantity through 1999. Total discharge volumes ({approx}2.7E+8 L) have been commensurate with predicted volumes to date. This document reports the results of all tritium analyses in groundwater as determined from the SALDS tritium-tracking network since the first SALDS wells were installed in 1992 through July 1999, and provides interpretation of these results as they relate to SALDS operation and its effect on groundwater. Hydrologic and geochemical information are synthesized to derive a conceptual model, which is in turn used to arrive at an appropriate approach to continued groundwater monitoring at the facility.
Date:
August 31, 2000
Creator:
Barnett, DB
Object Type:
Report
System:
The UNT Digital Library
Tank Farm WM-182 and WM-183 Heel Slurry Samples PSD Results
Particle size distribution (PSD) analysis of INTEC Tank Farm WM-182 and WM-183 heel slurry samples were performed using a modified Horiba LA-300 PSD analyzer at the RAL facility. There were two types of testing performed: typical PSD analysis, and setting rate testing. Although the heel slurry samples were obtained from two separate vessels, the particle size distribution results were quite similar. The slurry solids were from approximately a minimum particle size of 0.5 mm to a maximum of 230 mm with about 90% of the material between 2-to-133 mm, and the cumulative 50% value at approximately 20 mm. This testing also revealed that high frequency sonication with an ultrasonic element may break-up larger particles in the WM-182 and WM-183 tank from heel slurries. This finding represents useful information regarding ultimate tank heel waste processing. Settling rate testing results were also fairly consistent with material from both vessels in that it appears that most of the mass of solids settle to an agglomerated, yet easily redispersed layer at the bottom. A dispersed and suspended material remained in the ''clear'' layer above the settled layer after about one-half an hour of settling time. This material had a statistical mode of approximately 5 …
Date:
August 31, 2000
Creator:
Batcheller, T. A. & Huestis, G. M.
Object Type:
Report
System:
The UNT Digital Library
Characterization of Ce-doped scintillating crystals for imaging electron beams at the APS linac
None
Date:
August 31, 2000
Creator:
Berg, W. J.; Lumpkin, A. H. & Yang, B. X.
Object Type:
Article
System:
The UNT Digital Library
Final Report U.S. Department of Energy Joint Inversion of Geophysical Data for Site Characterization and Restoration Monitoring
The purpose of this project was to conduct basic research leading to significant improvements in the state-of-the-art of geophysical imaging of the shallow subsurface. Geophysical techniques are commonly used for underground imaging for site characterization and restoration monitoring. in order to improve subsurface imaging, the objective was to develop improved methods for interpreting geophysical data collected in the field, by developing better methods for relating measured geophysical properties, such as seismic velocity and electrical conductivity, to hydrogeology parameters of interest such as porosity, saturation, and soil composition. They met the objectives using an approach that combined laboratory experiments, comparison to available field data, rock physics theories, and modeling, to find relationships between geophysical measurements, hydrogeological parameters and soil composition. The primary accomplishments of this project in the last year (FY99) were that they completed the laboratory measurements of ultrasonic velocities in soils at low pressures and the measurements of complex electrical conductivity in those same soils; they used x-ray computed microtomography to image the microstructure of several soil samples; they used rock physics theories and modeling to relate the geophysical measurements to the microstructure and hydrological properties; they developed a theoretical technique for relating compressional and shear wave velocities to …
Date:
July 31, 2000
Creator:
Berge, P. A.; Berryman, J. G.; Bertete-Aguirre, H.; Bonner, B. P.; Roberts, J. J. & Wildenschild, D.
Object Type:
Report
System:
The UNT Digital Library
The Harper Herald (Harper, Tex.), Vol. 70, No. 42, Ed. 1 Tuesday, October 31, 2000
Weekly newspaper from Harper, Texas that includes local, state, and national news along with advertising.
Date:
October 31, 2000
Creator:
Bishop, Karen
Object Type:
Newspaper
System:
The Portal to Texas History
Photocatalytic and Chemical Oxidation of Organic Compounds in Supercritical Carbon Dioxide
The goal of the proposed research is to develop new chemistry for the removal of organic contaminants from supercritical carbon dioxide. This has application in processes used for continuous cleaning and extraction of parts and waste materials. Cleaning and extraction using supercritical carbon dioxide (scCO2) can be applied to the solution of a wide range of environmental and pollution prevention problems in the DOE complex. The objectives at the outset of the project were to: (1) determine if photocatalytic or other clean oxidation chemistry can be applied to the removal of organic or inorganic contaminants that are introduced into supercritical carbon dioxide during its use as an extraction and cleaning medium. The target will be contaminants left in solution after the bulk of solutes have been separated from the fluid phase by changing pressure and/or temperature (but not evaporating the CO2). This is applicable to development of efficient separations and will strengthen pollution prevention strategies that eliminate hazardous solvents and cleaning agents. (2) explore the use of supercritical carbon dioxide as a solvent for the photocatalytic oxidation of organic compounds and to compare it to other types of oxidation chemistry. This will add to the fundamental understanding of photocatalytic oxidation …
Date:
December 31, 2000
Creator:
Blake, Daniel M.
Object Type:
Report
System:
The UNT Digital Library
Calculation: Values and Consumption Rates of Locally Produced Food and Tap Water for the Receptor of Interest
This calculation produces standard statistical data on the consumption of locally produced food and tap water. The results of this calculation provide input parameters for the GENII-S (Leigh et al. 1993) computer code to support calculation of Biosphere Dose Conversion Factors (BDCF) for the nominal performance (groundwater contamination) scenario and the volcanic eruption (contamination of soil by volcanic ash deposition) scenario. The requirement and parameters for these data are identified in ''Identification Of The Critical Group (Consumption Of Locally Produced Food And Tap Water)'' (CRWMS M&O 2000a). This calculation is performed in accordance with the ''Development Plan for Calculation: Values and Consumption Rates of Locally Produced Food and Tap Water for the Receptor of Interest'' (CRWMS M&O 2000b).
Date:
July 31, 2000
Creator:
Bland, J.
Object Type:
Report
System:
The UNT Digital Library
NOx Control Options and Integration for US Coal Fired Boilers Quarterly Progress Report: July-September 2000
This report summarizes the research that has been performed by Reaction Engineering International (REI) during the last three months on demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for firing US coals. The focus of our efforts during the last six months have been on: (1) Field Tests for RRI at the Conectiv BL England Station Unit No.1, a 130 MW cyclone fired boiler; (2) Extending our Computational Fluid Dynamics (CFD) based NOx model to accommodate the chemistry for Rich Reagent Injection (RRI) in cyclone fired boilers; (3) Applying the NOx model to evaluate RRI systems integrated into a boiler with Over Fired Air (OFA) and Selective Non-Catalytic Reduction (SNCR); (4) Field Tests of the REI Corrosion Probe at the Conectiv BL England Station Unit No.1; (5) Commence engineering study of ammonia adsorption mechanisms for Fly Ash; (6) Presentation of current program accomplishments and plans for future work to DoE staff members at NETL-FE (Pittsburgh); and (7) Presentation of preliminary field test results for RRI to EPRI CNCIG.
Date:
October 31, 2000
Creator:
Bockelie, Michael J.
Object Type:
Report
System:
The UNT Digital Library
Measurement of d{sigma}/dy for high mass Drell-Yan e+ e- pairs at CDF
None
Date:
October 31, 2000
Creator:
Bodek, Atie
Object Type:
Article
System:
The UNT Digital Library
University Press (Beaumont, Tex.), Vol. 76, No. 41, Ed. 1 Friday, March 31, 2000
Semiweekly newspaper from Lamar University in Beaumont, Texas that includes local, national, and campus news along with advertising.
Date:
March 31, 2000
Creator:
Bordeman, Christina
Object Type:
Newspaper
System:
The Portal to Texas History