States

Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, October 1-December 31, 1982 (open access)

Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, October 1-December 31, 1982

The overall objective of the Westinghouse coal gasification program is to demonstrate the viability of the Westinghouse pressurized, fluidized bed, gasification system for the production of medium-Btu fuel gas for syngas, electrical power generation, chemical feedstocks, or industrial fuels and to obtain performance and scaleup data for the process and hardware. Progress reports are presented for the following tasks: (1) operation and maintenance of the process development unit (PDU); (2) process analysis; (3) cold flow scaleup facility; (4) process component engineering and design; and (5) laboratory support studies involving gas solids flow modeling and coal/ash behavior. 9 figures, 19 tables.
Date: April 21, 1983
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Gene-enzyme telationships in somatic cells and their organismal derivatives in higher plants. Progress report (open access)

Gene-enzyme telationships in somatic cells and their organismal derivatives in higher plants. Progress report

Progress is reported in the following subject areas: (1) chemistry of the arogenate molecule; (2) plant enzymology at the organismal level; (3) isolation of regulatory mutants in tobacco; and (4) stability of the haploid state in Nicotiana sylvestris.
Date: April 21, 1980
Creator: Jensen, R. A.
Object Type: Report
System: The UNT Digital Library
Annual environmental monitoring report: calendar year 1981 (open access)

Annual environmental monitoring report: calendar year 1981

The environment locally surrounding Mound was monitored primarily for tritium and plutonium-238. The results are reported for CY-1981. The environmental medium analyzed included air, water, vegetation, foodstuffs, and sediment. The average concentrations of plutonium-238 and tritium were within the applicable standards (adopted by the US DOE) for radioactive species.
Date: April 21, 1982
Creator: Farmer, B. M. & Carfagno, D. G.
Object Type: Report
System: The UNT Digital Library
Volume reduction system for solid and liquid TRU waste from the nuclear fuel cycle: October--December 1977 (open access)

Volume reduction system for solid and liquid TRU waste from the nuclear fuel cycle: October--December 1977

A bench-scale incinerator for the investigation of unusual particulate and gaseous radioactive material in the incinerator off-gas was assembled and equipment checkout was begun. Modifications to a glovebox to be used for the demonstration phase of incinerator-ash immobilization are approximately 80% completed with demonstration to begin next quarter. The curing time for ash-cement pressed pellets was optimized by periodic crush-strength testing of open-air and underwater cured samples. Leach tests were performed at 70 and 100/sup 0/C to simulate normal and extreme storage conditions. Long-term leach tests were initiated on plutonium-238 doped ash-cement pressed pellets in distilled water at ambient temperature. Pressed pellets of bone char, ash, and sludge-ash in several mixtures were fabricated and tested to establish pressing and curing parameters. Leach tests were also performed on bone char-cement pressed pellets. Curing studies have been conducted on the pressed pellet matrix to define differences between curing in the open atmosphere and under water. Leachability studies have been initiated on the pressed pellet ash/cement matrix in distilled water at ambient, 70 and 100/sup 0/C. Also, leachability studies on doped plutonium-238 pressed ash/cement pellets and pressed bone char/cement pellets in distilled water at ambient temperature have been conducted. Compressive strengths of bone …
Date: April 21, 1978
Creator: Luthy, D. F. & Bond, W.H.
Object Type: Report
System: The UNT Digital Library
Preliminary planning study for safety relief valve experiments in a Mark III BWR pressure suppression system (open access)

Preliminary planning study for safety relief valve experiments in a Mark III BWR pressure suppression system

In response to a request from the Water Reactor Safety Research Division of the US NRC, a preliminary study is provided which identifies key features and consideration involved in planning a comprehensive in-plant Safety Relief Valve experimental program for a Mark III containment design. The report provides identification of program objectives, measurement system requirements, and some details quantifying expected system response. In addition, a preliminary test matrix is outlined which involves a supporting philosophy intended to enhance the usefulness of the experimental results for all members of the program team: experimentalists, analysts, and plant operator.
Date: April 21, 1980
Creator: McCauley, E.W. & Holman, G.S.
Object Type: Report
System: The UNT Digital Library
Interim report: studies of boron deposition near geothermal power plants (open access)

Interim report: studies of boron deposition near geothermal power plants

Measurements in the Geysers area from April until October 1979 when the onset of seasonal rains limited field work are presented. Field studies involved the following three basic types of measurements: cooling tower drift deposition, plant ecological studies, and animal population studies. Brief summaries of the data are presented to demonstrate the types of information obtained. (MHR)
Date: April 21, 1980
Creator: Koranda, J.J.
Object Type: Report
System: The UNT Digital Library
Linear induction accelerator parameter options (open access)

Linear induction accelerator parameter options

The principal undertaking of the Beam Research Program over the past decade has been the investigation of propagating intense self-focused beams. Recently, the major activity of the program has shifted toward the investigation of converting high quality electron beams directly to laser radiation. During the early years of the program, accelerator development was directed toward the generation of very high current (>10 kA), high energy beams (>50 MeV). In its new mission, the program has shifted the emphasis toward the production of lower current beams (>3 kA) with high brightness (>10/sup 6/ A/(rad-cm)/sup 2/) at very high average power levels. In efforts to produce these intense beams, the state of the art of linear induction accelerators (LIA) has been advanced to the point of satisfying not only the current requirements but also future national needs.
Date: April 21, 1986
Creator: Birx, D.L.; Caporaso, G.J. & Reginato, L.L.
Object Type: Report
System: The UNT Digital Library
Qualification of tribological materials and coatings for use in sodium. [LMFBR] (open access)

Qualification of tribological materials and coatings for use in sodium. [LMFBR]

This paper describes some of the essential performance measures used to qualify materials for tribological applications in liquid sodium environments and summarizes relative properties of some of the newer tribological materials now qualified for use in sodium systems.
Date: April 21, 1980
Creator: Johnson, R. N. & Farwick, D. G.
Object Type: Article
System: The UNT Digital Library
Silicon-on ceramic process: silicon sheet growth and device development for the large-area silicon sheet task of the Low-Cost Solar Array Project. Quarterly report No. 14, January 1-March 31, 1980 (open access)

Silicon-on ceramic process: silicon sheet growth and device development for the large-area silicon sheet task of the Low-Cost Solar Array Project. Quarterly report No. 14, January 1-March 31, 1980

The purpose of this research program is to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by coating inexpensive ceramic substrates with a thin layer of polycrystalline silicon. The coating methods to be developed are directed toward a minimum-cost process for producing solar cells with a terrestrial conversion efficiency of 11% or greater. By applying a graphite coating to one face of a ceramic substrate, molten silicon can be made to wet only that graphite-coated face and produce uniform, thin layers of large-grain polycrystalline silicon; thus, only a minimal quantity of silicon is consumed. A dip-coating method for putting silicon on ceramic (SOC) has been shown to produce solar-cell-quality sheet silicon. This method and a continuous-coating process also being investigated have excellent scale-up potential which offers an outstanding, cost-effective way to manufacture large-area solar cells. The dip-coating investigation has shown that, as the substrate is pulled from the molten silicon, crystallization continues to occur from previously grown silicon. Therefore, as the substrate length is increased (as would be the case in a scaled-up process), the expectancy for larger crystallites increases. Results and accomplishments are reported. (WHK)
Date: April 21, 1980
Creator: Whitehead, A B; Zook, J D; Grung, B L; McHenry, K; Schuldt, S B & Chapman, P W
Object Type: Report
System: The UNT Digital Library
Innovative Clean Coal Technology (ICCT): 500 MW demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NO sub x ) emissions from coal-fired boilers (open access)

Innovative Clean Coal Technology (ICCT): 500 MW demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NO sub x ) emissions from coal-fired boilers

This quarterly report discusses the technical progress of an Innovative Clean Coal Technology (ICCT) demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NO{sub x}) emissions from coal-fired boilers. The project is being conducted at Georgia Power Company's Plant Hammond Unit 4 located near Rome, Georgia. The primary goal of this project is the characterization of the low NO{sub x} combustion equipment through the collection and analysis of long-term emissions data. A target of achieving fifty percent NO{sub x} reduction using combustion modifications has been established for the project. The project provides a stepwise retrofit of an advanced overfire air (AOFA) system followed by low NO{sub x} burners (LNB). During each test phase of the project, diagnostic, performance, long-term, and verification testing will be performed. These tests are used to quantify the NO{sub x} reductions of each technology and evaluate the effects of those reductions on other combustion parameters such as parameters such as particulate characteristics and boiler efficiency.
Date: April 21, 1992
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Decommissioning of Division of Military Application equipment at Richland Operations Office for period ending March 31, 1975 (open access)

Decommissioning of Division of Military Application equipment at Richland Operations Office for period ending March 31, 1975

The scope of the decommissioning work provides for (1) the removal of all Division of Military Application (DH) fabrication and inspection equipment held in standby status in the 234-5Z Building, (2) disposition of all contaminated equipment and materials removed by packaging for 20-year retrievable storage, (3) reclamation of salvageable materials and equipment for use on site by other Energy Research and Development Administration contractors, and (4) restoration of cleared-out areas for other future Richland Operations Office programs.
Date: April 21, 1975
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Thermal analysis of LOFT containment vessel penetrations S-5E and S-6A (open access)

Thermal analysis of LOFT containment vessel penetrations S-5E and S-6A

Thermal analysis of the LOFT containment vessel penetration S-6A was conducted for steady-state operation and blowdown transients. Penetration S-6A is a 20-inch pipe through which passes a 10-inch pipe from the steam generator containing 600/sup 0/F steam. Recommendations for penetration S-5E were based on the analysis of penetration S-6A. Penetration S-5E is an 18-inch pipe through which pass a 4-inch pipe containing the steam generator feedwater at 430/sup 0/F and a 0.5-inch pipe containing sample water at 600/sup 0/F. The thermal analysis is necessary to determine the maximum temperature gradient in the containment vessel around the penetrations. The outside of the penetrations protrude into a room adjacent to the containment vessel which will be maintained at a minimum temperature of 50/sup 0/F. The steady-state temperature inside the containment vessel was assumed to be 100/sup 0/F. Table I of LOFT Containment Vessel Specification S-1 was used for inside transient temperatures.
Date: April 21, 1970
Creator: Condie, K.G.
Object Type: Report
System: The UNT Digital Library
2005 Annual Health Physics Report for HEU Transparency Program (open access)

2005 Annual Health Physics Report for HEU Transparency Program

During the 2005 calendar year, LLNL provided health physics support for the Highly Enriched Uranium Transparency Program (HEU-TP) in external and internal radiation protection and technical expertise into matters related to BDMS radioactive sources and Russian radiation safety regulatory compliance. For the calendar year 2005, there were 161 person-trips that required dose monitoring of the U.S. monitors. Of the 161 person-trips, 149 person-trips were SMVs and 12 person-trips were Transparency Monitoring Office (TMO) trips. Additionally, there were 11 monitoring visits by TMO monitors to facilities other than UEIE and 3 to UEIE itself. There were two monitoring visits (source changes) that were back to back with 16 monitors. Each of these concurring visits were treated as single person-trips for dosimetry purposes. Counted individually, there were 191 individual person-visits in 2005. The LLNL Safety Laboratories Division provided the dosimetry services for the HEU-TP monitors.
Date: April 21, 2006
Creator: Radev, R
Object Type: Report
System: The UNT Digital Library
DSP-Based dual-polarity mass spectrum pattern recognition for bio-detection (open access)

DSP-Based dual-polarity mass spectrum pattern recognition for bio-detection

The Bio-Aerosol Mass Spectrometry (BAMS) instrument analyzes single aerosol particles using a dual-polarity time-of-flight mass spectrometer recording simultaneously spectra of thirty to a hundred thousand points on each polarity. We describe here a real-time pattern recognition algorithm developed at Lawrence Livermore National Laboratory that has been implemented on a nine Digital Signal Processor (DSP) system from Signatec Incorporated. The algorithm first preprocesses independently the raw time-of-flight data through an adaptive baseline removal routine. The next step consists of a polarity dependent calibration to a mass-to-charge representation, reducing the data to about five hundred to a thousand channels per polarity. The last step is the identification step using a pattern recognition algorithm based on a library of known particle signatures including threat agents and background particles. The identification step includes integrating the two polarities for a final identification determination using a score-based rule tree. This algorithm, operating on multiple channels per-polarity and multiple polarities, is well suited for parallel real-time processing. It has been implemented on the PMP8A from Signatec Incorporated, which is a computer based board that can interface directly to the two one-Giga-Sample digitizers (PDA1000 from Signatec Incorporated) used to record the two polarities of time-of-flight data. By using …
Date: April 21, 2006
Creator: Riot, V; Coffee, K; Gard, E; Fergenson, D; Ramani, S & Steele, P
Object Type: Article
System: The UNT Digital Library
Fluorine for Hydrogen Exchange in the Hydrofluorobenzene Derivatives C6HxF(6-x), where x = 2, 3, 4 and 5 by Monomeric [1,2,4-(Me3C)3C5H2]2CeH; The Solid State Isomerization of [1,2,4-(Me3C)3C5H2]2Ce(2,3,4,5-C6HF4) to [1,2,4-(Me3C)3C5H2]2Ce(2,3,4,6-C6HF4) (open access)

Fluorine for Hydrogen Exchange in the Hydrofluorobenzene Derivatives C6HxF(6-x), where x = 2, 3, 4 and 5 by Monomeric [1,2,4-(Me3C)3C5H2]2CeH; The Solid State Isomerization of [1,2,4-(Me3C)3C5H2]2Ce(2,3,4,5-C6HF4) to [1,2,4-(Me3C)3C5H2]2Ce(2,3,4,6-C6HF4)

The reaction between monomeric bis(1,2,4-tri-t-butylcyclopentadienyl)cerium hydride, Cp'2CeH, and several hydrofluorobenzene derivatives is described. The aryl derivatives that are the primary products, Cp'2Ce(C6H5-xFx) where x = 1,2,3,4, are thermally stable enough to be isolated in only two cases, since all of them decompose at different rates to Cp'2CeF and a fluorobenzyne; the latter is trapped by either solvent when C6D6 is used or by a Cp'H ring when C6D12 is the solvent. The trapped products are identified by GCMS analysis after hydrolysis. The aryl derivatives are generated cleanly by reaction of the metallacycle, Cp'((Me3C)2C5H2C(Me2)CH2)Ce, with a hydrofluorobenzene and the resulting arylcerium products, in each case, are identified by their 1H and 19F NMR spectra at 20oC. The stereochemical principle that evolves from these studies is that the thermodynamic isomer is the one in which the CeC bond is flanked by two ortho-CF bonds. This orientation is suggested to arise from the negative charge that is localized on the ipso-carbon atom due to Co(delta+)-Fo(delta-) polarization. The preferred regioisomer is determined by thermodynamic rather than kinetic effects; this is illustrated by the quantitative, irreversible solid-state conversion at 25oC over two months of Cp'2Ce(2,3,4,5-C6HF4) to Cp'2Ce(2,3,4,6-C6HF4), an isomerization that involves a CeC(ipso) for C(ortho)F …
Date: April 21, 2008
Creator: Andersen, Richard; Werkema, Evan L. & Andersen, Richard A.
Object Type: Article
System: The UNT Digital Library
Borehole Seismic Monitoring of Injected CO2 at the Frio Site (open access)

Borehole Seismic Monitoring of Injected CO2 at the Frio Site

As part of a small scale sequestration test (about 1500 tonsof CO2) in a saline aquifer, time-lapse borehole seismic surveys wereconducted to aid in characterization of subsurface CO2 distribution andmaterial property changes induced by the injected CO2. A VSP surveydemonstrated a large increase (about 75 percent) in seismic reflectivitydue to CO2 injection and allowed estimation of the spatial extent of CO2induced changes. A crosswell survey imaged a large seismic velocitydecrease (up to 500 m/s) within the injection interval and provided ahigh resolution image of this velocity change which maps the subsurfacedistribution of CO2 between two wells. Numerical modeling of the seismicresponse uses the crosswell measurements to show that this small CO2volume causes a large response in the seismic reflectivity. This resultdemonstrates that seismic detection of small CO2 volumes in salineaquifers is feasible and realistic.
Date: April 21, 2006
Creator: Daley, Thomas M.; Myer, Larry R.; Hoversten, G.M.; Peterson, JohnE. & Korneev, Valeri A.
Object Type: Article
System: The UNT Digital Library
A Beamline for High Pressure Studies at the Advanced Light Source With a Superconducting Bending Magnet as the Source (open access)

A Beamline for High Pressure Studies at the Advanced Light Source With a Superconducting Bending Magnet as the Source

A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/{Delta}E {approx} 7000) and a W/B{sub 4}C multilayer (E/{Delta}E {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.
Date: April 21, 2005
Creator: Kunz, M.; MacDowell, A. A.; Caldwell, W. A.; Cambie, D.; Celestre, R. S.; Domning, E. E. et al.
Object Type: Article
System: The UNT Digital Library
Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration, Annual Technical Progress Report: 2005 (open access)

Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration, Annual Technical Progress Report: 2005

Molecular modeling was employed to both visualize and probe our understanding of carbon dioxide sequestration within a bituminous coal. A large-scale (>20,000 atoms) 3D molecular representation of Pocahontas No. 3 coal was generated. This model was constructed based on a the review data of Stock and Muntean, oxidation and decarboxylation data for aromatic clustersize frequency of Stock and Obeng, and the combination of Laser Desorption Mass Spectrometry data with HRTEM, enabled the inclusion of a molecular weight distribution. The model contains 21,931 atoms, with a molecular mass of 174,873 amu, and an average molecular weight of 714 amu, with 201 structural components. The structure was evaluated based on several characteristics to ensure a reasonable constitution (chemical and physical representation). The helium density of Pocahontas No. 3 coal is 1.34 g/cm{sup 3} (dmmf) and the model was 1.27 g/cm{sup 3}. The structure is microporous, with a pore volume comprising 34% of the volume as expected for a coal of this rank. The representation was used to visualize CO{sub 2}, and CH{sub 4} capacity, and the role of moisture in swelling and CO{sub 2}, and CH{sub 4} capacity reduction. Inclusion of 0.68% moisture by mass (ash-free) enabled the model to swell by …
Date: April 21, 2006
Creator: Evanseck, Jeffrey D.; Madura, Jeffry D. & Mathews, Jonathan P.
Object Type: Report
System: The UNT Digital Library
FLUOR HANFORD DECOMMISSIONING UPDATE (open access)

FLUOR HANFORD DECOMMISSIONING UPDATE

Fluor Hanford is completing D&D of the K East Basin at the U.S. Department of Energy's (DOE's) Hanford Site in southeastern Washington State this spring, with demolition expected to begin in June. Located about 400 yards from the Columbia River, the K East Basin is one of two indoor pools that formerly contained irradiated nuclear fuel, radioactive sludge and tons of contaminated debris. In unique and path-breaking work, workers finished removing the spent fuel from the K Basins in 2004. In May 2007, workers completed vacuuming the sludge into containers in the K East Basin, and transferring it into containers in the K West Basin. In December, they finished vacuuming the remainder of K West Basin sludge into these containers. The K East Basin was emptied of its radioactive inventory first because it was more contaminated than the K West Basin, and had leaked in the past. In October 2007, Fluor Hanford began physical D&D of the 8,400-square foot K East Basin by pouring approximately 14-inches of grout into the bottom of it. Grout is a type of special cement used for encasing waste. Two months later, Fluor Hanford workers completed sluicing contaminated sand from the large filter that had …
Date: April 21, 2008
Creator: MS, GERBER
Object Type: Article
System: The UNT Digital Library
CARBOXYLATIONS AND DECARBOXYLATIONS (open access)

CARBOXYLATIONS AND DECARBOXYLATIONS

A brief survey of decarboxylation reactions and carboxylation reactions that are known or presumed in biological systems will be presented. While a considerable number of amino acid decarboxylations are known, their mechanisms will not be included in the present discussion but will be reserved for a later paper in the symposium. The remaining decarboxylation reactions may be subdivided into oxidative and nonoxidative decarboxylations. In most cases, these reactions are practically irreversible except when coupled with suitable energy-yielding systems. The carboxylation reactions which are useful in the formation of carbon-carbon bonds in biological systems seem to fall into two or three groups: those which exhibit an apparent ATP requirement, and those which exhibit a reduced pyridine nucleotide requirement, and those which exhibit no apparent ATP requirement. Of the first group at least four cases, and possibly six or seven, are known, and one interpretation of them involves the preliminary formation of 'active' carbon dioxide, generally in the form of a carbonic acid-phosphoric acid anhydride. Those exhibiting no apparent ATP requirement seem to be susceptible to classifications as enol carboxylations in which the energy level of the substrate compound is high, rather than that of the carbon dioxide. There appear to be …
Date: April 21, 1959
Creator: Calvin, Melvin & Pon, Ning G.
Object Type: Report
System: The UNT Digital Library
Proceedings of RIKEN BNL Research Center Workshop entitled Hydrodynamics in Heavy Ion Collisions and QCD Equation of State (Volume 88) (open access)

Proceedings of RIKEN BNL Research Center Workshop entitled Hydrodynamics in Heavy Ion Collisions and QCD Equation of State (Volume 88)

The interpretation of relativistic heavy-ion collisions at RHIC energies with thermal concepts is largely based on the relative success of ideal (nondissipative) hydrodynamics. This approach can describe basic observables at RHIC, such as particle spectra and momentum anisotropies, fairly well. On the other hand, recent theoretical efforts indicate that dissipation can play a significant role. Ideally viscous hydrodynamic simulations would extract, if not only the equation of state, but also transport coefficients from RHIC data. There has been a lot of progress with solving relativistic viscous hydrodynamics. There are already large uncertainties in ideal hydrodynamics calculations, e.g., uncertainties associated with initial conditions, freezeout, and the simplified equations of state typically utilized. One of the most sensitive observables to the equation of state is the baryon momentum anisotropy, which is also affected by freezeout assumptions. Up-to-date results from lattice quantum chromodynamics on the transition temperature and equation of state with realistic quark masses are currently available. However, these have not yet been incorporated into the hydrodynamic calculations. Therefore, the RBRC workshop 'Hydrodynamics in Heavy Ion Collisions and QCD Equation of State' aimed at getting a better understanding of the theoretical frameworks for dissipation and near-equilibrium dynamics in heavy-ion collisions. The topics …
Date: April 21, 2008
Creator: Karsch, F.; Kharzeev, D.; Molnar, K.; Petreczky, P. & Teaney, D.
Object Type: Article
System: The UNT Digital Library
Security Proof for Password Authentication in TLS-Verifier-based Three-Party Group Diffie-Hellman (open access)

Security Proof for Password Authentication in TLS-Verifier-based Three-Party Group Diffie-Hellman

The internet has grown greatly in the past decade, by some numbers exceeding 47 million active web sites and a total aggregate exceeding100 million web sites. What is common practice today on the Internet is that servers have public keys, but clients are largely authenticated via short passwords. Protecting these passwords by not storing them in the clear on institutions's servers has become a priority. This paper develops password-based ciphersuites for the Transport Layer Security (TLS) protocol that are: (1) resistant to server compromise; (2) provably secure; (3) believed to be free from patent and licensing restrictions based on an analysis of relevant patents in the area.
Date: April 21, 2008
Creator: Chevassut, Olivier; Milner, Joseph & Pointcheval, David
Object Type: Report
System: The UNT Digital Library
Predicting dissolution patterns in variable aperture fractures: 1. Development and evaluation of an enhanced depth-averaged computational model (open access)

Predicting dissolution patterns in variable aperture fractures: 1. Development and evaluation of an enhanced depth-averaged computational model

Water-rock interactions within variable-aperture fractures can lead to dissolution of fracture surfaces and local alteration of fracture apertures, potentially transforming the transport properties of the fracture over time. Because fractures often provide dominant pathways for subsurface flow and transport, developing models that effectively quantify the role of dissolution on changing transport properties over a range of scales is critical to understanding potential impacts of natural and anthropogenic processes. Dissolution of fracture surfaces is controlled by surface-reaction kinetics and transport of reactants and products to and from the fracture surfaces. We present development and evaluation of a depth-averaged model of fracture flow and reactive transport that explicitly calculates local dissolution-induced alterations in fracture apertures. The model incorporates an effective mass transfer relationship that implicitly represents the transition from reaction-limited dissolution to transport-limited dissolution. We evaluate the model through direct comparison to previously reported physical experiments in transparent analog fractures fabricated by mating an inert, transparent rough surface with a smooth single crystal of potassium dihydrogen phosphate (KDP), which allowed direct measurement of fracture aperture during dissolution experiments using well-established light transmission techniques [Detwiler, et al., 2003]. Comparison of experiments and simulations at different flow rates demonstrate the relative impact of the …
Date: April 21, 2006
Creator: Detwiler, R L & Rajaram, H
Object Type: Article
System: The UNT Digital Library
PREPARATION AND CHARACTERIZATION OF POROUS WALLED HOLLOW GLASS MICROSPHERES (open access)

PREPARATION AND CHARACTERIZATION OF POROUS WALLED HOLLOW GLASS MICROSPHERES

Porous-walled hollow glass microspheres (PWHGMs) of a modified alkali borosilicate composition have been successfully fabricated by combining the technology of producing hollow glass microspheres (HGMs) with the knowledge associated with porous glasses. HGMs are first formed by a powder glass--flame process, which are then transformed to PWHGMs by heat treatment and subsequent treatment in acid. Pore diameter and pore volume are most influenced by heat treatment temperature. Pore diameter is increased by a factor of 10 when samples are heat treated prior to acid leaching; 100 {angstrom} in non-heat treated samples to 1000 {angstrom} in samples heat treated at 600 C for 8 hours. As heat treatment time is increased from 8 hours to 24 hours there is a slight shift increase in pore diameter and little or no change in pore volume.
Date: April 21, 2008
Creator: Raszewski, F; Erich Hansen, E; Ray Schumacher, R & David Peeler, D
Object Type: Article
System: The UNT Digital Library