Ab initio study of optical absorption spectra of semiconductors and conjugated polymers (open access)

Ab initio study of optical absorption spectra of semiconductors and conjugated polymers

The effects of electron-hole interaction on the optical properties of a variety of materials have been calculated using an ab initio method based on solving the Bethe-Salpeter equation. Results on selected semiconductors, insulators, and semiconducting polymers are presented. In the cases of alpha-quartz (SiO2) and poly-phenylene-vinylene, resonant excitonic states qualitatively alter the absorption spectra.
Date: April 30, 2000
Creator: Tiago, M.L.; Chang, Eric K.; Rohlfing, Michael & Louie, Steven G.
Object Type: Article
System: The UNT Digital Library
Advanced Cuttings Transport Study Quarterly Technical Report: January 1999-April 2000 (open access)

Advanced Cuttings Transport Study Quarterly Technical Report: January 1999-April 2000

ACTS flow loop is now operational under elevated pressure and temperature. Currently, experiments with water under pressure and temperature are being conducted. Based on the analysis of Fann 70 data, empirical correlations defining the shear stress as a function of temperature, pressure and the shear rate have been developed for Petrobras synthetic drilling fluids. PVT equipment has been modified for testing Synthetic drilling fluids. Initial calibration tests have been conducted by using water. Currently, the base oil of the Petrobras synthetic drilling fluid is being tested. Foam flow experiments have been conducted. Currently, more experiments are being conducted while data are being analyzed to characterize the rheology of the foam. Cuttings transport experiments have been conducted using air, water and cuttings. Preliminary results have shown that it may not be possible to avoid cuttings bed deposition under any practical combination of air and water flow rates. Foam stability analyses have been conducted. Effects of salt and oil concentration on the foam stability have been investigated. A software for controlling the data sampling and data storage during cuttings monitoring process have been developed.
Date: April 30, 2000
Creator: Kuru, Ergun; Miska, Stefan; Takach, Nicholas; Ashenayi, Kaveh; Kane, Gerald; Volk, Len et al.
Object Type: Report
System: The UNT Digital Library
Department of Energy manpower assessment brief Number 46: Nuclear engineering enrollments and degrees (open access)

Department of Energy manpower assessment brief Number 46: Nuclear engineering enrollments and degrees

Based on a survey of 42 institutions, nuclear engineering enrollments and degrees decreased overall in 1999, continuing a steady decline of several years.
Date: April 30, 2000
Creator: unknown
Object Type: Report
System: The UNT Digital Library
DOE manpower assessment brief Number 47: Health physics enrollments and degrees (open access)

DOE manpower assessment brief Number 47: Health physics enrollments and degrees

Based on a survey of 49 institutions, health physics enrollments increased at the bachelor's and doctoral level, while master's enrollments decreased. Bachelor's and master's degrees increased slightly and doctoral degrees decreased.
Date: April 30, 2000
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Effect of Radiation on Spinel Ceramics for Permanent Containers for Nuclear Waste Transportation and Storage. (open access)

Effect of Radiation on Spinel Ceramics for Permanent Containers for Nuclear Waste Transportation and Storage.

None
Date: April 30, 2000
Creator: Adams, J.; Cowgill, M.; Moskowitz, P. & Rokhvarger, A.
Object Type: Article
System: The UNT Digital Library
Effect of Radiation on Spinel Ceramics for Permanent Containers for Nuclear Waste Transportation and Storage. (open access)

Effect of Radiation on Spinel Ceramics for Permanent Containers for Nuclear Waste Transportation and Storage.

None
Date: April 30, 2000
Creator: Adams, J.; Cowgill, M.; Moskowitz, P. & Rokhvarger, A.
Object Type: Article
System: The UNT Digital Library
Hand-held radio-isotope detection and identification instrument (open access)

Hand-held radio-isotope detection and identification instrument

An instrument combining an array of Cadmium-Zinc-Telluride (CZT) detectors, a NaI scintillator, and two {sup 3}He neutron detectors has been constructed. The instrument uses the CZT array to identify radioactive materials. As an example of this application, the 3 {sigma} Minimum Detectable Activity for the 375 keV peak of {sup 238}Pu is less than 1 gram at a distance of 20 cm for a 100-second counting time. The 2 x 2 NaI scintillator has a dual purpose. First, it is used to supplement the CZT array for identification of high-energy gammas, such as those from {sup 60}Co. Second, the principle use of the NaI scintillator is to help search for radioactive material and to find a suitable measurement location on a suspect package for the CZT-based isotope-identification measurement. This detector also produces energy-corrected exposure-rate data. The {sup 3}He neutron detectors provide an additional confirmation of the presence of some plutonium isotopes. The neutron sensitivity is 90 counts per second at 20 cm from a moderated {sup 252}Cf neutron source.
Date: April 30, 2000
Creator: Quam, W. M.
Object Type: Article
System: The UNT Digital Library
IMPROVED OIL RECOVERY IN MISSISSIPPIAN CARBONATE RESERVOIRS OF KANSAS - NEAR TERM - CLASS 2 (open access)

IMPROVED OIL RECOVERY IN MISSISSIPPIAN CARBONATE RESERVOIRS OF KANSAS - NEAR TERM - CLASS 2

This annual report describes progress during the final year of the project entitled ''Improved Oil Recovery in Mississippian Carbonate Reservoirs in Kansas''. This project funded under the Department of Energy's Class 2 program targets improving the reservoir performance of mature oil fields located in shallow shelf carbonate reservoirs. The focus of the project was development and demonstration of cost-effective reservoir description and management technologies to extend the economic life of mature reservoirs in Kansas and the mid-continent. As part of the project, tools and techniques for reservoir description and management were developed, modified and demonstrated, including PfEFFER spreadsheet log analysis software. The world-wide-web was used to provide rapid and flexible dissemination of the project results through the Internet. A summary of demonstration phase at the Schaben and Ness City North sites demonstrates the effectiveness of the proposed reservoir management strategies and technologies. At the Schaben Field, a total of 22 additional locations were evaluated based on the reservoir characterization and simulation studies and resulted in a significant incremental production increase. At Ness City North Field, a horizontal infill well (Mull Ummel No.4H) was planned and drilled based on the results of reservoir characterization and simulation studies to optimize the location …
Date: April 30, 2000
Creator: Carr, Timothy R.; Green, Don W. & Willhite, G. Paul
Object Type: Report
System: The UNT Digital Library
Improving Paper Machine Efficiency (open access)

Improving Paper Machine Efficiency

None
Date: April 30, 2000
Creator: Allun, Cyrus
Object Type: Report
System: The UNT Digital Library
Interim report on task 1.2: near equilibrium processing requirements - attrition milling appendices part 2 of 2 to Lawrence Livermore National Laboratory for contract b345772 (open access)

Interim report on task 1.2: near equilibrium processing requirements - attrition milling appendices part 2 of 2 to Lawrence Livermore National Laboratory for contract b345772

None
Date: April 30, 2000
Creator: Stewart, M W A; Vance, E R; Day, R A; Eddowes, T & Moricca, S
Object Type: Report
System: The UNT Digital Library
Interim report on task 1.2: near equilibrium processing requirements - attrition milling part 1 of 2 to Lawrence Livermore National for contract b345772 (open access)

Interim report on task 1.2: near equilibrium processing requirements - attrition milling part 1 of 2 to Lawrence Livermore National for contract b345772

The objective of Task 1.2 has only partly been achieved as the work on Pu/U-formulations and to a significant degree on Th/U-formulations has been performed under grinding/blending conditions that did not replicate plant-like fabrication processes, particularly in the case with the small glovebox attritor. Nevertheless the results do show that actinide-rich particles, not present in specimens made via the alkoxide-route (equilibrium conditions), occur when the grinding process is not efficient enough to ensure that high-fired PuO{sub 2}, ThO{sub 2} and UO{sub 2} particles are below a critical size. Our current perception is that the critical size for specimens sintered at 1350 C for 4 hours is about 5 {micro}m in diameter. The critical size is difficult to estimate, as it is equal to the starting diameter of actinide oxides just visible within brannerite regions. Our larger scale attritor experiments as well as experience with wet and dry ball milling suggests that acceptable mineralogy and microstructure can be obtained by dry milling via attritor and ball mills. This is provided that appropriate attention is paid to the size and density of the grinding media, grinding additives that reduce caking of the powder, and in the case of attritors the grinding speed …
Date: April 30, 2000
Creator: Stewart, M W A; Vance, E R; Day, R A; Eddowes, T & Moricca, S
Object Type: Report
System: The UNT Digital Library
Interim report task 2: performance testing - task 2.4: natural mineral analog studies physical and chemical characteristics of brannerite in natural systems to Lawrence Livermore National Laboratory under contract B345772 (open access)

Interim report task 2: performance testing - task 2.4: natural mineral analog studies physical and chemical characteristics of brannerite in natural systems to Lawrence Livermore National Laboratory under contract B345772

To investigate the long-term alteration behavior of brannerite, we have undertaken a study of 13 natural samples from various geological environments, including granites, granitic pegmatites, quartz veins, and placer deposits. Literature data and U-Th-Pb chemical dating carried out in this work indicate that the samples range in age from approximately 20 Ma to 1580 Ma. Where independent age data or estimates are available for comparison, the U-Th-Pb chemical ages are in reasonable agreement for the younger samples, but the older samples tend to show evidence for Pb loss (up to about 80%), a common feature of metamict Nb, Ta, and Ti oxide minerals. Our results show that many of the samples exhibit only minor alteration, usually within small patches, microfractures, or around the rims of the brannerite crystals. Other samples consist of variable amounts of unaltered and altered brannerite. Heavily altered samples may contain anatase and thorite as fine-grained alteration products. Certain samples exhibited fracturing of the associated rock matrix or mineral phase in the immediate vicinity of the brannerite grains. These fractures contain U bearing material and indicate that some U migrated locally from the source brannerite.
Date: April 30, 2000
Creator: Lumpkin, G. R.; Colella, M. & Leung, S. H. F.
Object Type: Report
System: The UNT Digital Library
Interim report task 3: immobilization process/equipment testing - task 3.4: non-destructive evaluation appendices part 2 of 2 to Lawrence Livermore National Laboratory under contract b345772 (open access)

Interim report task 3: immobilization process/equipment testing - task 3.4: non-destructive evaluation appendices part 2 of 2 to Lawrence Livermore National Laboratory under contract b345772

None
Date: April 30, 2000
Creator: Stewart, M W A; Vance, E R; Day, R A & Lumpkin, G R
Object Type: Report
System: The UNT Digital Library
LIMB demonstration project extension and Coolside demonstration: A DOE assessment (open access)

LIMB demonstration project extension and Coolside demonstration: A DOE assessment

The goal of the US Department of Energy (DOE) Clean Coal Technology (CCT) program is to furnish the energy marketplace with a number of advanced, more efficient, and environmentally responsible coal utilization technologies through demonstration projects. These projects seek to establish the commercial feasibility of the most promising advanced coal technologies that have already reached the proof-of-concept stage. This document serves as a DOE post-project assessment of the CCT Round 1 project ``LIMB Demonstration Project Extension and Coolside Demonstration'', described in a report to Congress (Babcock and Wilcox 1987), a paper by DePero et al. (1992), and in a report by Goots et al. (1992). The original limestone injection multistage burner (LIMB) demonstration work was conducted by Babcock and Wilcox Company (B and W) beginning in 1984, under the sponsorship of the US Environmental Protection Agency (EPA) and the State of Ohio Coal Development Office (OCDO). In 1987, B and W and the Ohio Edison Company agreed to extend the full-scale demonstration of LIMB technology under the sponsorship of DOE through its CCT Program, and with support from OCDO and Consolidation Coal Company, now known as CONSOL. In a separate effort, CONSOL had been developing another flue gas desulfurization (FGD) …
Date: April 30, 2000
Creator: National Energy Technology Laboratory (U.S.)
Object Type: Report
System: The UNT Digital Library
MCFC PRODUCT DESIGN IMPROVEMENT (open access)

MCFC PRODUCT DESIGN IMPROVEMENT

The objective of the DOE program is to advance the direct carbonate fuel cell technology to a level suitable for commercial entry. The specific objectives of the DOD's initiative on 2 MW Fuel Cell Fixed Base Power Plant are: (1) To provide a detailed engineering design, development and cost estimate of the 2 MW fuel cell fixed base dual fuel power plant for DOD applications. Installation and operational support systems will also be developed. (2) To construct a full-size MW-class dual fuel power plant simulator. These objectives are planned to be achieved in the program coordinated with the Department of Energy, which has been funding a multiyear natural gas fueled direct fuel cell power plant program (DE-FC21-95MC31184) for civilian applications. Because many DARPA and DOE objectives are similar, the coordinated program activities are considered the most cost-effective for accomplishment of the program objectives. The DARPA/DOE joint program was launched in 1994. The DOE part of the program is expected to continue to Year 2000. The final output of this DOE program is to construct and operate a 2 MW power plant on an East Coast site. The site will be accessible to DOD energy/environmental systems base planners and logistics personnel …
Date: April 30, 2000
Creator: unknown
Object Type: Report
System: The UNT Digital Library
National Ignition Facility Quarterly Status Report Second Quarter 2000, Jan-Mar 2000 (open access)

National Ignition Facility Quarterly Status Report Second Quarter 2000, Jan-Mar 2000

The Project provides for the design, procurement, construction, assembly, installation, and acceptance testing of the National Ignition Facility (NIF), an experimental inertial confinement fusion facility intended to achieve controlled thermonuclear fusion in the laboratory by imploding a small capsule containing a mixture of the hydrogen isotopes deuterium and tritium. The NIF will be constructed at the Lawrence Livermore National Laboratory (LLNL), Livermore, California as determined by the Record of Decision made on December 19, 1996, as a part of the Stockpile Stewardship and Management Programmatic Environmental Impact Statement.
Date: April 30, 2000
Creator: Moses, E.
Object Type: Report
System: The UNT Digital Library
Scaled Vitrification System III (SVS III) Process Development and Laboratory Tests at the West Valley Demonstration Project (open access)

Scaled Vitrification System III (SVS III) Process Development and Laboratory Tests at the West Valley Demonstration Project

At the West Valley Demonstration Project (WVDP),the Vitrification Facility (VF)is designed to convert the high-level radioactive waste (HLW)stored on the site to a stable glass for disposal at a Department of Energy (DOE)-specified federal repository. The Scaled Vitrification System III (SVS-III)verification tests were conducted between February 1995 and August 1995 as a supplemental means to support the vitrification process flowsheet, but at only one seventh the scale.During these tests,the process flowsheet was refined and optimized. The SVS-III test series was conducted with a focus on confirming the applicability of the Redox Forecasting Model, which was based on the Index of Feed Oxidation (IFO)developed during the Functional and Checkout Testing of Systems (FACTS)and SVS-I tests. Additional goals were to investigate the prototypical feed preparation cycle and test the new target glass composition. Included in this report are the basis and current designs of the major components of the Scale Vitrification System and the results of the SVS-III tests.The major subsystems described are the feed preparation and delivery, melter, and off-gas treatment systems. In addition,the correlation between the melter's operation and its various parameters;which included feed rate,cold cap coverage,oxygen reduction (redox)state of the glass,melter power,plenum temperature,and airlift analysis;were developed.
Date: April 30, 2000
Creator: Jain, V.; Barnes, S. M.; Bindi, B. G. & Palmer, R. A.
Object Type: Report
System: The UNT Digital Library
Second-Generation PFBC Systems R&D (open access)

Second-Generation PFBC Systems R&D

No work was performed; the two remaining Multi Annular Swirl Burner test campaigns are on hold pending selection of a new test facility (replacement for the shut down UTSI burner test facility) and identification of associated testing costs. The Second-Generation PFB Combustion Plant conceptual design prepared in 1987 is being updated to reflect the benefit of pilot plant test data and the latest advances in gas turbine technology. The updated plant is being designed to operate with 95 percent sulfur capture and a single Siemens Westinghouse (SW) 501G gas turbine. Using carbonizer and gas turbine data generated by Foster Wheeler (FW) and SW respectively, Parsons Infrastructure & Technology prepared preliminary plant heat and material balances based on carbonizer operating temperatures of 1700 and 1800 F and found the former to yield the higher plant efficiency. As a result, 1700 F has been selected as the preferred operating condition for the carbonizer. The 501G gas turbine has an air compressor discharge temperature of 811EF and an exhaust temperature of 1140 F. Both of these streams represent high sources of heat and must be cooled, the air to 600 F to be compatible with a 650 F PCFB pressure vessel design temperature …
Date: April 30, 2000
Creator: Robertson, Archie
Object Type: Report
System: The UNT Digital Library
Advanced Hydrogen Transport Membranes for Vision 21 Fossil Fuel Plants (open access)

Advanced Hydrogen Transport Membranes for Vision 21 Fossil Fuel Plants

Eltron Research Inc., and team members, are developing an environmentally benign, inexpensive, and efficient method for separating hydrogen from gas mixtures produced during industrial processes, such as coal gasification. This project was motivated by the National Energy Technology Laboratory (NETL) Vision 21 initiative which seeks to economically eliminate environmental concerns associated with the use of fossil fuels. This objective is being pursued using dense membranes based in part on Eltron-patented ceramic materials with a demonstrated ability for proton and electron conduction. The technical goals are being addressed by modifying single-phase and composite membrane composition and microstructure to maximize proton and electron conductivity without loss of material stability. Ultimately, these materials must enable hydrogen separation at practical rates under ambient and high-pressure conditions, without deactivation in the presence of feedstream components such as carbon dioxide, water, and sulfur. During this quarter, it was demonstrated that increasing the transition metal loading in a model perovskite composition resulted in an increase in hydrogen flux. Improved flux corresponded to the emergence of additional phases in the ceramic membrane, and highest flux was achieved for a composite consisting of pseudo-cubic and rhombohedral perovskite phases. A 0.9-mm thick membrane of this material generated a hydrogen flux …
Date: April 30, 2001
Creator: Roark, Shane E.; Sammells, Tony F.; Calihman, Adam E.; Pitzman, Lyrik Y.; Calcar, Pamela M. Van; Mackay, Richard A. et al.
Object Type: Report
System: The UNT Digital Library
AMBIENT PM2.5 SAMPLING AND ANALYSIS (open access)

AMBIENT PM2.5 SAMPLING AND ANALYSIS

This is the third semi-annual technical progress report summarizing observations and tentative conclusions drawn from evaluations of the data captured to date from the operation of the ambient PM{sub 2.5} speciation sites in a geographical area encompassing southeastern Ohio, western Pennsylvania, and northwestern West Virginia. The overall goal of this program, called the Upper Ohio River Valley Project (UORVP), is to better understand the relationship between coal-based power system emissions and ambient air quality in the upper Ohio River Valley region through the collection of chemically resolved or speciated data. In order to provide a ''stand alone'' document, this report contains updated versions of Section 1 (Introduction) and Section 2 (Experimental) in their entirety from the first report.
Date: April 30, 2001
Creator: unknown
Object Type: Report
System: The UNT Digital Library
AMBIENT PM2.5 SAMPLING AND ANALYSIS (open access)

AMBIENT PM2.5 SAMPLING AND ANALYSIS

This is the third semi-annual technical progress report summarizing observations and tentative conclusions drawn from evaluations of the data captured to date from the operation of the ambient PM{sub 2.5} speciation sites in a geographical area encompassing southeastern Ohio, western Pennsylvania, and northwestern West Virginia. The overall goal of this program, called the Upper Ohio River Valley Project (UORVP), is to better understand the relationship between coal-based power system emissions and ambient air quality in the upper Ohio River Valley region through the collection of chemically resolved or speciated data. In order to provide a ''stand alone'' document, this report contains updated versions of Section 1 (Introduction) and Section 2 (Experimental) in their entirety from the first report.
Date: April 30, 2001
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Applied techniques for high bandwidth data transfers across wide area networks (open access)

Applied techniques for high bandwidth data transfers across wide area networks

Large distributed systems such as Computational/Data Grids require large amounts of data to be co-located with the computing facilities for processing. Ensuring that the data is there in time for the computation in today's Internet is a massive problem. From our work developing a scalable distributed network cache, we have gained experience with techniques necessary to achieve high data throughput over high bandwidth Wide Area Networks (WAN). In this paper, we discuss several hardware and software design techniques and issues, and then describe their application to an implementation of an enhanced FTP protocol called GridFTP. We also describe results from two applications using these techniques, which were obtained at the Supercomputing 2000 conference.
Date: April 30, 2001
Creator: Lee, Jason; Gunter, Dan; Tierney, Brian; Allcock, Bill; Bester, Joe; Bresnahan, John et al.
Object Type: Article
System: The UNT Digital Library
Characterization of Contaminant Transport using Naturally-Occurring U-Series Disequilibria - Final Report - 05/01/1997 - 04/30/2001 (open access)

Characterization of Contaminant Transport using Naturally-Occurring U-Series Disequilibria - Final Report - 05/01/1997 - 04/30/2001

The interactions of mixed wastes containing radionuclides with solid rock surface and the mobility of the radionuclides in aquifer systems depend not only on the chemistry of the nuclides and the physico-chemical effects of radioactive decay, but also on the site-specific hydrogeology. Thus, to characterize contaminant transport, it is best to cross-check figures derived from any small-scale laboratory experiments over limited times with that obtained from field-oriented, natural analog studies. We propose such a study using the naturally-occurring U and Th decay-series disequilibria. The work of ours and other researchers have shown that the parent/daughter disequilibrium patterns existing in groundwater systems can be modeled in terms of local nuclide mass balance to arrive at such information as the rock-water contact time (fluid flow) and rates of contaminant transport, taking into account the retardation effect due to nuclide/rock interaction contaminants at INEL by grouping them into three categories, represented by isotopes of (1) Th and Pa, (2) U and (3) Ra. Mass spectrometric measurements of these elements will be emphasized in order to minimize sample size requirements and to maximize precision. Results will form the data base for a model code for computing: (1) Fluid residence time (transport rates) in the …
Date: April 30, 2001
Creator: Murrell, Michael T. & Ku, Teh-Lung
Object Type: Report
System: The UNT Digital Library
Clean Cities National Partner Awards: Clean Cities Fact Sheet (open access)

Clean Cities National Partner Awards: Clean Cities Fact Sheet

This fact sheet briefly describes each of the 10 winners of the Clean Cities National Partner Awards.
Date: April 30, 2001
Creator: LaRocque, T.
Object Type: Book
System: The UNT Digital Library