Resource Type

Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight-binding approaches (open access)

Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight-binding approaches

Semiempirical interatomic potentials are developed for silicon and carbon by modeling the total energy of the system using tight-binding approaches. The parameters of the models were obtained by fitting to results from accurate first-principles Local Density Functional calculations. Applications to the computation of phonons as a function of volume for diamond-structured silicon and carbon and the thermal expansions for silicon and diamond yields results which agree well with experiment. The physical origin of the negative thermal expansion observed in silicon is explained. A tight-binding total energy model is generated capable of describing carbon systems with a variety of atomic coordinations and topologies. The model reproduces the total energy versus volume curves of various carbon polytypes as well as phonons and elastic constants of diamond and graphite. The model has also been used in the molecular-dynamics simulation of the properties of carbon clusters. The calculated ground-state geometries of small clusters (C{sub 2}--C{sub 10}) correlates well with results from accurate quantum chemical calculations, and the structural trend of clusters from C{sub 2} to C{sub 60} are investigated. 67 refs., 19 figs.
Date: October 25, 1991
Creator: Xu, Chunhui.
System: The UNT Digital Library
Monthly energy review, October 1991. [Contains glossary] (open access)

Monthly energy review, October 1991. [Contains glossary]

This report presents current data on production, consumption, stocks, imports, exports, and prices of the principal energy commodities in the United States. Also included are data on international production of crude oil, consumption of petroleum products, petroleum stocks, and production of electricity from nuclear-powered facilities. 36 figs., 57 tabs.
Date: October 25, 1991
Creator: unknown
System: The UNT Digital Library
The Brady Handgun Control Act: Constitutional Issues (open access)

The Brady Handgun Control Act: Constitutional Issues

The Brady Handgun Control Act established a five-day waiting period for handgun purchases, during which local law enforcement can make reasonable efforts to conduct background checks in available records and block and sales to convicted felons and other disqualified persons. This report reviews the background of federal gun control legislation, analyzes the conflict in the courts over the constitutionality under the Tenth Amendment of the duties placed on local law enforcement, and considers the implications of the decisions for Brady Act enforcement.
Date: October 25, 1995
Creator: Schrader, Dorothy
System: The UNT Digital Library
Iraq-Kuwait: United Nations Security Council Resolutions Test and Votes -- 1991 (open access)

Iraq-Kuwait: United Nations Security Council Resolutions Test and Votes -- 1991

This report lists the 12 adopted United Nations Security Council resolutions relating to the Iraq-Kuwait situation through October 1991. The texts of these resolutions, along with the votes by members of the Council, are included in this report.
Date: October 25, 1991
Creator: Browne, Marjorie Ann
System: The UNT Digital Library
Shot report, Holo-17-Holo-22 Rex-9 (open access)

Shot report, Holo-17-Holo-22 Rex-9

We report on a series of holographic shots using explosives to generate ejecta from lead. These experiments covered a range of geometries including point initiation and plane wave initiation for the H.E., and using a gas-fill in the cavity where the ejecta was produced. The final experiment, Rex-9 was a Fabry-Perot experiment at Site 300 which provided the velocity history of the lead surface for the purpose of normalizing the code being used to calculate the position of the lead surface in these experiments. The focus of this report is on the experimental technique rather than on the size measurements. We want to insure that the advances in mechanical design and experimental technique that were made during these experiments are preserved in future experiments. 8 figs., 2 tabs.
Date: October 25, 1990
Creator: McMillan, C.; Whipkey, R. & Vance, P.
System: The UNT Digital Library
Fundamental Studies of Water Pretreatment of Coal (open access)

Fundamental Studies of Water Pretreatment of Coal

During the seventh quarter, water pretreatment experiments were done at lower pressures (1000 psig), with early H{sub 2}O injection or continuous H{sub 2}O injection, and with demineralized coals. In addition, a set of blank experiments was done with all four coals in helium at the following conditions: 350{degrees}C; 4000 psig; 20 minutes. An additional experiment was done with the Zap lignite at atmospheric pressure. Helium was used instead of nitrogen since it can be obtained in highly pure grades. The purpose of the blank experiments is to determine how much of the water pretreatment process is a thermal and/or pressure effort. The residues from the standard water pretreatment experiments with Illinois and Pittsburgh coals were subjected to analysis by TG-FTIR, solvent extraction, solvent swelling, oxygen reactivity index and donor solvent liquefaction. The pyridine extractables were analyzed. With regard to liquefaction behavior, improvements in the yields of oils and toluene solubles are observed for selected Illinois and Pittsburgh coals at longer pretreatment times ({ge} 60 minutes).
Date: October 25, 1991
Creator: Serio, M. A.; Solomon, P. R.; Kroo, E.; Charpenay, S. & Bassilakis, R.
System: The UNT Digital Library
Topics in theoretical surface science (open access)

Topics in theoretical surface science

The energetics and structures of clean and adsorbate covered surfaces are investigated in this dissertation. First, the formalism, within the Corrected Effective Medium (CEM) method, for calculating the surface energy of a clean surface is derived. The surface energies for many different metals and their low index surfaces are presented. The minimization of the surface energy is then used to predict the multilayer relaxation of the Al(111), (100), Ni(100), (110) and Fe(100) surfaces. Extensions of the surface CEM formalism to calculate the binding energies of ordered adsorbates on metals surfaces are also derived. The minimization of the binding energy allowed determination of the binding heights, sites and the extent of induced multilayer relaxation for H and N atoms on the Fe(110), (100) and W(110) surfaces. The last topic deals with the dynamics of the epitaxial growth of metals on metal surfaces. The CEM method was first modified by making approximations to enable faster evaluations of the potential and its corresponding forces for molecular dynamics simulations. The goal of these simulations was to identify the important steps in the formation of equilibrium epitaxial structures. 180 refs., 31 figs., 18 tabs.
Date: October 25, 1991
Creator: Todd, R.
System: The UNT Digital Library
FY90 milestone report for the CIT (Compact Ignition Tokamak) project: Localizability of electron-cyclotron heating power (open access)

FY90 milestone report for the CIT (Compact Ignition Tokamak) project: Localizability of electron-cyclotron heating power

Estimates of the localizability of electron-cyclotron heating power are made for the Compact Ignition Tokamak. A particular heating scenario is examined, namely, the fundamental O-mode, injected nearly perpendicular to the toroidal magnetic field. The absorption depth due to finite T{sub e} is very small, about 1 cm, near the q = 2 surface. Absorption is even better localized near q = 1. Several issues that might lead to degraded localizability are reviewed. Use of an intense, pulsed microwave source is the only issue with a possibly significant impact. 3 refs.
Date: October 25, 1990
Creator: Smith, G. R.
System: The UNT Digital Library
Optical techniques for measurement of high temperatures (open access)

Optical techniques for measurement of high temperatures

The availability of instrumentation to measure the high outlet gas temperature of a particle bed reactor is a topic of some concern. There are a number of possible techniques with advantages and disadvantages. In order to provide some baseline choice of instrumentation, a review has been conducted of these various technologies. This report summarizes the results of this review for a group of technologies loosely defined as optical techniques (excluding optical pyrometry). The review has concentrated on a number of questions for each technology investigated. These are: (1) Description of the technology, (2) Anticipated sensitivity and accuracy, (3) Requirements for implementation, (4) Necessary development time and costs, (5) Advantages and disadvantages of the technology. Each of these areas was considered for a technology and a large number of technologies were considered in a review of the literature. Based upon this review it was found that a large number of methods exist to measure temperatures in excess of 2000 K. None of the methods found were ideal. Four methods, however, appeared to warrant further consideration: opto-mechanical expansion thermometry, surface Raman spectroscopy, gas-phase Raman spectroscopy and coherent anti-Stokes Raman spectroscopy (CARS). These techniques will be discussed further in this document.
Date: October 25, 1991
Creator: Veligdan, J.T.
System: The UNT Digital Library
Temperature Control Feedback Loops for the Linac Upgrade Side Coupled Cavities at Fermilab (open access)

Temperature Control Feedback Loops for the Linac Upgrade Side Coupled Cavities at Fermilab

The linac upgrade project at Fermilab will replace the last 4 drift-tube linac tanks with seven side coupled cavity strings. This will increase the beam energy from 200 to 400 MeV at injection into the Booster accelerator. The main objective of the temperature loop is to control the resonant frequency of the cavity strings. A cavity string will constant of 4 sections connected with bridge couplers driven with a 12 MW klystron at 805 MHz. Each section is a side coupled cavity chain consisting of 16 accelerating cells and 15 side coupling cells. For the linac upgrade, 7 full cavity strings will be used. A separate temperature control system is planned for each of the 28 accelerating sections, the two transition sections, and the debuncher section. The cavity strings will be tuned to resonance for full power beam loaded conditions. A separate frequency loop is planned that will sample the phase difference between a monitor placed in the end cell of each section and the rf drive. The frequency loop will control the set point for the temperature loop which will be able to maintain the resonant frequency through periods within beam or rf power. The frequency loop will need …
Date: October 25, 1990
Creator: Crisp, Jim
System: The UNT Digital Library
(Biotechnology for the conversion of lignocellulosics) (open access)

(Biotechnology for the conversion of lignocellulosics)

This report summarizes the results of the traveler's participation in the International Energy Agency (IEA) Network planning meeting for Biotechnology for the Conversion of Lignocellulosics,'' held at the Institut Francais du Petrole (IFP), Rueil-Malmaison, France. It also summarizes the results of discussions held at Aston University, Birmingham, UK, with Dr. Martin Beevers with whom the traveler is attempting to initiate a collaborative research project that will be beneficial to ongoing research programs at Oak Ridge National Laboratory (ORNL). The itinerary for the trip is given in Appendix A; the names of the people contacted are listed in Appendix B. Also, pertinent information about the Institut Francais du Petrole is attached (Appendix C). 1 tab.
Date: October 25, 1990
Creator: Woodward, J.
System: The UNT Digital Library
Fundamental Studies of Water Pretreatment of Coal. Seventh Quarterly Report, April 1, 1991--June 30, 1991 (open access)

Fundamental Studies of Water Pretreatment of Coal. Seventh Quarterly Report, April 1, 1991--June 30, 1991

During the seventh quarter, water pretreatment experiments were done at lower pressures (1000 psig), with early H{sub 2}O injection or continuous H{sub 2}O injection, and with demineralized coals. In addition, a set of blank experiments was done with all four coals in helium at the following conditions: 350{degrees}C; 4000 psig; 20 minutes. An additional experiment was done with the Zap lignite at atmospheric pressure. Helium was used instead of nitrogen since it can be obtained in highly pure grades. The purpose of the blank experiments is to determine how much of the water pretreatment process is a thermal and/or pressure effort. The residues from the standard water pretreatment experiments with Illinois and Pittsburgh coals were subjected to analysis by TG-FTIR, solvent extraction, solvent swelling, oxygen reactivity index and donor solvent liquefaction. The pyridine extractables were analyzed. With regard to liquefaction behavior, improvements in the yields of oils and toluene solubles are observed for selected Illinois and Pittsburgh coals at longer pretreatment times ({ge} 60 minutes).
Date: October 25, 1991
Creator: Serio, M. A.; Solomon, P. R.; Kroo, E.; Charpenay, S. & Bassilakis, R.
System: The UNT Digital Library
[Oxygenated octane enhancers: Syngas to isobutylene]. Technical progress report No. 8, January 1, 1993--March 31, 1993 (open access)

[Oxygenated octane enhancers: Syngas to isobutylene]. Technical progress report No. 8, January 1, 1993--March 31, 1993

The goal of this program is to develop a catalyst and a process for the conversion of syngas to isobutylene. However, due to the low conversion and selectivity generally experienced by the industry in direct conversion of syngas to isobutylene, indirect conversion via branched C{sub 4} alcohol intermediates is being explored. The objectives of the current program are to develop a catalyst and process for the conversion of syngas to isobutanol and to evaluate the commercial potential of the new process. The research program underway at UOP will identify and optimize key catalyst and process characteristics. This report covers the modification and shake-down of a fixed-bed pilot plant (No. 700) for the testing of catalysts and catalyst combinations. A separate syngas feed system has been added to an existing fixed bed Fischer-Tropsch pilot plant and new reactors are constructed to avoid catalyst cross contamination. Shake-down testing with a commercial Cu/Zn/Al oxide catalyst alone and in combination with a basic Mg/Al MOSS (Metal Oxide Solid Solution) catalyst have demonstrated good CO and H{sub 2} conversion. However, contamination of the product by residual Fischer-Tropsch product in the exit lines and the liquid gas chromatograph (GC) has prevented accurate product analyses. A separate …
Date: October 25, 1993
Creator: Barger, P. T.
System: The UNT Digital Library
Development of an extraction process for removal of heteroatoms from coal liquids. Technical progress report No. 6, 1 July, 1993--30 September, 1993 (open access)

Development of an extraction process for removal of heteroatoms from coal liquids. Technical progress report No. 6, 1 July, 1993--30 September, 1993

The objective of this contract is to develop a CO{sub 2}-water extraction process for the removal of heteroatoms from coal-derived naphtha, diesel, and jet fuel. Coal liquids are characterized by their high content of heteroatoms. Conventional techniques could remove the heteroatoms from coal liquids, but at a high hydrogen consumption and at a high cost. A successful development of the CO{sub 2}-water extraction process will increase the environmental acceptability of coal liquids and reduce the H{sub 2} requirements for the upgrading of coal liquids. This report describes activities under two tasks: Task 2.0, Feed procurement and Task 3.0, Process variable screening studies.
Date: October 25, 1993
Creator: Gala, H. B.
System: The UNT Digital Library
Awards of Attorney's Fees to Small Businesses and Labor Organizations that Prevail Against the NLRB or OSHA: H.R. 1987, 106th Congress (open access)

Awards of Attorney's Fees to Small Businesses and Labor Organizations that Prevail Against the NLRB or OSHA: H.R. 1987, 106th Congress

H.R. 1987, 106th Congress, the Fair Access to Indemnity and Reimbursement (FAIR) Act, which was reported by the Committee on Education and the Workforce on October 14, 1999, would make it easier for small businesses and labor organizations that prevail against the NLRB or OSHA, in administrative or court proceedings, to recover their attorneys' fees from the government. It would do so by requiring fees to be awarded automatically in cases to which it applied, instead of only when the government's position was not substantially justified.
Date: October 25, 1999
Creator: Cohen, Henry
System: The UNT Digital Library
Iraq-Kuwait: United Nations Security Council Resolutions Tests and Votes – 1991 (open access)

Iraq-Kuwait: United Nations Security Council Resolutions Tests and Votes – 1991

None
Date: October 25, 1991
Creator: unknown
System: The UNT Digital Library
D-Zero Central Calorimeter Pressure Vessel and Vacuum Vessel Safety Notes (open access)

D-Zero Central Calorimeter Pressure Vessel and Vacuum Vessel Safety Notes

The relief valve and relief piping capacity was calculated to be 908 sefm air. This exceeds all relieving conditions. The vessel also has a rupture disc with a 2640 scfm air stamped capacity. In order to significantly decrease the amount of time required to fill the cryostats, it is desired to raise the setpoint of the 'operating' relief valve on the argon storage dewar to 20 psig from its existing 16 psig setting. This additional pressure increases the flow to the cryostats and will overwhelm the relief capacity if the temperature of the modules within these vessels is warm enough. Using some conservative assumptions and simple calculations within this note, the maximum average temperature that the modules within each cryostat can be at prior to filling from the storage dewar with liquid argon is at least 290 K. The average temperature of the module mass for any of the three cryostats can be as high as 290 K prior to filling that particular cryostat. This should not be confused with the average temperature of a single type or location which is useful in protecting the modules-not necessarily the vessel itself. A few modules of each type and at different elevations …
Date: October 25, 1990
Creator: Rucinski, R. & Luther, R.
System: The UNT Digital Library
Full-scale demonstration Low-NO{sub x} Cell{trademark} Burner retrofit. Quarterly report No. 8, 1 July, 1992--30 September, 1992: Revision 1 (open access)

Full-scale demonstration Low-NO{sub x} Cell{trademark} Burner retrofit. Quarterly report No. 8, 1 July, 1992--30 September, 1992: Revision 1

The Full Scale Demonstration Low-NO{sub x} Cell{trademark} Burner (LNCB{trademark}) project involves retrofitting the two-nozzle cell burners at Dayton Power and Light`s, 605 MW(e) J.M. Stuart Unit No. 4 boiler near Aberdeen, Ohio with LNCB{trademark} (a burner and integral No{sub x} port). Previous pilot-scale tests have shown such an arrangement to achieve 50% reduction in NO{sub x} emission levels. This full-scale project will determine the commercial applicability of this technology. Long-term testing via a Continuous Emission Monitor (CEM) began in August, 1992. CEM testing will continue until Spring of 1993 when Unit No. 4 comes off line for its annual outage which at this time is scheduled for April 4, 1993. A key item remaining to be evaluated as part of the long term testing is furnace tube wall corrosion. H{sub 2}S probing similar to optimized test probing was repeated during the week of August 17, 1992. During the Spring `93 outage, ultrasonic testing of the furnace wall tubes as well as destructive examination of samples from the corrosion test panel will be accomplished.
Date: October 25, 1993
Creator: unknown
System: The UNT Digital Library
Revalidation studies of Mark 16 experiments: J70 (open access)

Revalidation studies of Mark 16 experiments: J70

The MGBS-TGAL combination of the J70 criticality modules was validated for Mark 16 lattices by H. K. Clark as reported in DPST-83-1025. Unfortunately, the records of the calculations reported can not be retrieved and the descriptions of the modeling used are not fully provided in DPST-83-1025. The report does not describe in detail how to model the experiments and how to set up the input. The computer output for the cases reported in the memorandum can not be located in files. The MGBS-TGAL calculations reported in DPST-83-1025 have been independently reperformed to provide retrievable record copies of the calculations, to provide a detailed description and discussion of the methodology used, and to serve as a training exercise for a novice criticality safety engineer. The current results reproduce Clark`s reported results to within about 0.01% or better. A procedure to perform these and similar calculations is given in this report, with explanation of the methodology choices provided. Copies of the computer output have been made via microfiche and will be maintained in APG files.
Date: October 25, 1993
Creator: Lee, S. Y.
System: The UNT Digital Library
Bioconversion of coal derived synthesis gas to liquid fuels. Final quarterly technical progress report, July 1, 1993--September 30, 1993 (open access)

Bioconversion of coal derived synthesis gas to liquid fuels. Final quarterly technical progress report, July 1, 1993--September 30, 1993

The overall objective of the project is to develop an integrated two stage fermentation process for conversion of coal-derived synthesis gas to a mixture of alcohols. This is achieved in two steps. In the first step, Butyribacterium methylotrophicum converts carbon monoxide (CO) to butyric and acetic acids. Subsequent fermentation of the acids by Clostridium acetobutylicum leads to the production of butanol and ethanol. The tasks for this quarter were: (1) development/isolation of superior strains for fermentation of syngas, (2) optimization of process conditions for fermentation of syngas, (3) evaluation of bioreactor configuration for improved mass transfer of syngas, (4) development of a membrane-based pervaporation system, (5) optimization of process conditions for reducing carbon and electron loss by H{sub 2}-CO{sub 2} fermentation, and (6) synthesis gas fermentation in single-stage by co-culture. Progress is reported in isolation of CO utilizing anaerobic strains; investigating the product profile for the fermentation of syngas by B. methylotrophicum; and determining the effect of carbon monoxide on growth of C. acetobutylicum.
Date: October 25, 1993
Creator: Jain, M. K.; Worden, R. M. & Grethlein, H.
System: The UNT Digital Library
Optical techniques for measurement of high temperatures (open access)

Optical techniques for measurement of high temperatures

The availability of instrumentation to measure the high outlet gas temperature of a particle bed reactor is a topic of some concern. There are a number of possible techniques with advantages and disadvantages. In order to provide some baseline choice of instrumentation, a review has been conducted of these various technologies. This report summarizes the results of this review for a group of technologies loosely defined as optical techniques (excluding optical pyrometry). The review has concentrated on a number of questions for each technology investigated. These are: (1) Description of the technology, (2) Anticipated sensitivity and accuracy, (3) Requirements for implementation, (4) Necessary development time and costs, (5) Advantages and disadvantages of the technology. Each of these areas was considered for a technology and a large number of technologies were considered in a review of the literature. Based upon this review it was found that a large number of methods exist to measure temperatures in excess of 2000 K. None of the methods found were ideal. Four methods, however, appeared to warrant further consideration: opto-mechanical expansion thermometry, surface Raman spectroscopy, gas-phase Raman spectroscopy and coherent anti-Stokes Raman spectroscopy (CARS). These techniques will be discussed further in this document.
Date: October 25, 1991
Creator: Veligdan, J. T.
System: The UNT Digital Library
Analysis of offsite emergency planning zones (EPZs) for the Rocky Flats Plant. Phase 3, Sitewide spectrum-of-accidents and bounding EPZ analysis (open access)

Analysis of offsite emergency planning zones (EPZs) for the Rocky Flats Plant. Phase 3, Sitewide spectrum-of-accidents and bounding EPZ analysis

This Charter provides the basis for a cooperative, interagency effort to conduct Phase III of the ``Analysis of Offsite Emergency Planning Zones (EPZs) for the Rocky Flats Plant`` Project. The purpose of this Charter is to define the Project and establish an Oversight Committee management structure together with responsibilities and commitments. This Charter establishes a commitment on the part of the signing agencies to participate in a Phase III EPZ analysis to refine existing EPZs for the Rocky Flats Plant. These agencies agree to commit resources to this Project to fulfill their identified roles. The specific types and levels of resources committed by each agency will be determined as part of the Project planning process. This Charter does not commit any agency to any specific level of effort or resources. It does, however, commit these agencies to support the Phase III analysis to completion.
Date: October 25, 1993
Creator: Petrocchi, A. J. & Smith, M. L.
System: The UNT Digital Library
Radiological impact of Par Pond drawdown from liquid effluent pathways (open access)

Radiological impact of Par Pond drawdown from liquid effluent pathways

The water level of Par Pond has been lowered over the past several months to reduce the effects in the event of catastrophic dam failure while assessing the condition of the dam and determining if repairs are necessary. In lowering the level of Par Pond, 60 billion liters of water containing low levels of tritium and cesium-137 were discharged to several onsite streams. SRS surface streams flow to the Savannah River. An assessment made to determine the total amount of tritium and Cs-137 discharged and to estimate the consequences to downstream Savannah River users. It is estimated that a total of 160 curies of tritium were displaced from Par Pond to the Savannah River between June 28, 1991 and September 19, 1991. This release could hypothetically result in a maximum individual dose of 3. 2{times}10{sup {minus}4} mrem and a total (80-km and drinking water populations) population dose of 1.4{times}10{sup {minus}2} person-rem. Likewise, a maximum individual dose of 5.0{times}10{sup {minus}2} mrem and a total population dose of 1.7{times}10{sup {minus}1} person- rem are predicted as a result of an estimated 0.21 curies of Cs-137 being discharged from Par Pond to the Savannah River.
Date: October 25, 1991
Creator: Carlton, W. H. & Hamby, D. M.
System: The UNT Digital Library
Director of Development and Administration: October 25, 1993 (open access)

Director of Development and Administration: October 25, 1993

Report for the finances of the Texas Human Rights Foundation regarding pending and declined grants for which the foundation has applied.
Date: October 25, 1993
Creator: unknown
System: The UNT Digital Library