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3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI (open access)

3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI

None
Date: January 1, 2000
Creator: Morel, J.
System: The UNT Digital Library
ACTINYL(VI) SPECIATION IN CONCENTRATED SODIUM CHLORIDE SOLUTIONS (open access)

ACTINYL(VI) SPECIATION IN CONCENTRATED SODIUM CHLORIDE SOLUTIONS

None
Date: January 1, 2000
Creator: Runde, W. & Neu, M.
System: The UNT Digital Library
AGE-RELATED CHANGES IN PU DEDUCED FROME XAFS DATA WITH A NEW SUPER-RESOLUTION FAST FOURIER TRANSFORM (open access)

AGE-RELATED CHANGES IN PU DEDUCED FROME XAFS DATA WITH A NEW SUPER-RESOLUTION FAST FOURIER TRANSFORM

None
Date: January 1, 2000
Creator: ZWEIG, G. & WOHLBERG, B.
System: The UNT Digital Library
Los Alamos Plutonium Facility Waste Management System (open access)

Los Alamos Plutonium Facility Waste Management System

None
Date: January 1, 2000
Creator: Smith, C. A. & Sparks, D.
System: The UNT Digital Library
All-Hot-Wire Chemical Vapor Deposition a-Si:H Solar Cells (open access)

All-Hot-Wire Chemical Vapor Deposition a-Si:H Solar Cells

Efficient hydrogenated amorphous silicon (a-Si:H) nip solar cells have been fabricated with all doped and undoped a-Si:H layers deposited by hot-wire chemical vapor deposition (HWCVD). The total deposition time of all layers, except the top ITO-contact, is less than 4 minutes.
Date: January 1, 2000
Creator: Iwaniczko, E.; Wang, Q.; Xu, Y.; Nelson, B. P.; Mahan, A. H.; Crandall, R. S. et al.
System: The UNT Digital Library
Analysis of Moisture and CO(2) Uptake in Anhydrous CdCl(2) Powders Used for Vapor CdCl(2) Treatment of CdS/CdTe PV Devices (open access)

Analysis of Moisture and CO(2) Uptake in Anhydrous CdCl(2) Powders Used for Vapor CdCl(2) Treatment of CdS/CdTe PV Devices

Water and CO(2) uptake in CdCl(2) powder precursors was investigated using thermogravimetric analysis/Fourier transform infrared spectroscopy (TGA/FTIR). Exposure of powders under ambient conditions shows that a steady-state hydration level near 9% (by weight) is achieved after brief exposure to room air.
Date: January 1, 2000
Creator: Mazur, T.; Gessert, T.; Martins, G. & Curtis, C.
System: The UNT Digital Library
Anomalous {gamma} {r_arrow} 3{pi} amplitude in a bound-state approach (open access)

Anomalous {gamma} {r_arrow} 3{pi} amplitude in a bound-state approach

The form factor for the anomalous process {gamma}{pi}{sup +} {r_arrow} pi{sub +}{pi}{sup 0}, which is presently being measured at CEBAF, is calculated in the Schwinger-Dyson approach in conjunction with an impulse approximation. The form factors obtained by the author are compared with the ones predicted by the simple constituent quark loop model, vector meson dominance and chiral perturbation theory, as well as the scarce already available data.
Date: January 1, 2000
Creator: Bistrovic, Bojan & Klabucar, Dubravko
System: The UNT Digital Library
APPLICATION OF FUZZY SET THEORY FOR EXPOSURE CONTROL IN BERYLLIUM PART MANUFACTURING (open access)

APPLICATION OF FUZZY SET THEORY FOR EXPOSURE CONTROL IN BERYLLIUM PART MANUFACTURING

None
Date: January 1, 2000
Creator: Parkinson, W.J. & Abeln, S.P.
System: The UNT Digital Library
AN ASSESSMENT OF MCNP WEIGHT WINDOWS (open access)

AN ASSESSMENT OF MCNP WEIGHT WINDOWS

The weight window variance reduction method in the general-purpose Monte Carlo N-Particle radiation transport code MCNPTM has recently been rewritten. In particular, it is now possible to generate weight window importance functions on a superimposed mesh, eliminating the need to subdivide geometries for variance reduction purposes. Our assessment addresses the following questions: (1) Does the new MCNP4C treatment utilize weight windows as well as the former MCNP4B treatment? (2) Does the new MCNP4C weight window generator generate importance functions as well as MCNP4B? (3) How do superimposed mesh weight windows compare to cell-based weight windows? (4) What are the shortcomings of the new MCNP4C weight window generator? Our assessment was carried out with five neutron and photon shielding problems chosen for their demanding variance reduction requirements. The problems were an oil well logging problem, the Oak Ridge fusion shielding benchmark problem, a photon skyshine problem, an air-over-ground problem, and a sample problem for variance reduction.
Date: January 1, 2000
Creator: HENDRICKS, J. S. & CULBERTSON, C. N.
System: The UNT Digital Library
AUTOMATED DECONTAMINATION OF NUCLEAR MATERIAL CONTAINERS AT LOS ALAMOS NATIONAL LABORATORY (open access)

AUTOMATED DECONTAMINATION OF NUCLEAR MATERIAL CONTAINERS AT LOS ALAMOS NATIONAL LABORATORY

None
Date: January 1, 2000
Creator: Dennison, D.K. & Gallant, D.A.
System: The UNT Digital Library
BAs-GaAs Semiconductor Alloys as a Photovoltaic Alternative to Nitride Alloys (open access)

BAs-GaAs Semiconductor Alloys as a Photovoltaic Alternative to Nitride Alloys

Nitrogen alloyed III-V semiconductor compounds have been intensely studied in recent years due to unusual effects caused by nitrogen alloying. These effects are exploited in band gap engineering for specific applications such as solar cells and blue lasers.
Date: January 1, 2000
Creator: Hart, G. L. W. & Zunger, A.
System: The UNT Digital Library
BGaInAs Alloys Lattice-Matched to GaAs for High-Efficiency Solar Cells (open access)

BGaInAs Alloys Lattice-Matched to GaAs for High-Efficiency Solar Cells

A novel alloy, BGaInAs, may prove useful in high-efficiency III-V multijunction solar cells.
Date: January 1, 2000
Creator: Geisz, J. F.; Friedman, D. J.; Olson, J. M.; Kurtz, S. R.; Reedy, R. C.; Swartzlander, A. B. et al.
System: The UNT Digital Library
Carbon dioxide sequestration by direct aqueous mineral carbonation (open access)

Carbon dioxide sequestration by direct aqueous mineral carbonation

Carbon dioxide sequestration by an ex-situ, direct aqueous mineral carbonation process has been investigated over the past two years. This process was conceived to minimize the steps in the conversion of gaseous CO2 to a stable solid. This meant combining two separate reactions, mineral dissolution and carbonate precipitation, into a single unit operation. It was recognized that the conditions favorable for one of these reactions could be detrimental to the other. However, the benefits for a combined aqueous process, in process efficiency and ultimately economics, justified the investigation. The process utilizes a slurry of water, dissolved CO2, and a magnesium silicate mineral, such as olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. These minerals were selected as the reactants of choice for two reasons: (1) significant abundance in nature; and (2) high molar ratio of the alkaline earth oxides (CaO, MgO) within the minerals. Because it is the alkaline earth oxide that combines with CO2 to form the solid carbonate, those minerals with the highest ratio of these oxides are most favored. Optimum results have been achieved using heat pretreated serpentine feed material, sodium bicarbonate and sodium chloride additions to the solution, and high partial pressure of CO2 (PCO2). Specific …
Date: January 1, 2000
Creator: O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P. & Turner, Paul C.
System: The UNT Digital Library
Carbon dioxide sequestration by direct mineral carbonation with carbonic acid (open access)

Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation, and the DOE National Energy Technology Laboratory. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3 -. The H+ reacts with the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted …
Date: January 1, 2000
Creator: O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P. & Turner, Paul C.
System: The UNT Digital Library
Carbon dioxide sequestration by ex-situ mineral carbonation (open access)

Carbon dioxide sequestration by ex-situ mineral carbonation

The process developed for carbon dioxide sequestration utilizes a slurry of water mixed with olivine- forsterite end member (Mg{sub 2}SiO{sub 4}), which is reacted with supercritical CO{sub 2} to produce magnesite (MgCO{sub 3}). Carbon dioxide is dissolved in water to form carbonic acid, which likely dissociates to H{sup +} and HCO{sub 3}{sup -}. The H{sup +} hydrolyzes the silicate mineral, freeing the cation (Mg{sup 2+}), which reacts with the HCO{sub 3}{sup -} to form the solid carbonate. Results of the baseline tests, conducted on ground products of the natural mineral, have demonstrated that the kinetics of the reaction are slow at ambient temperature (22 degrees C) and subcritical CO{sub 2} pressures (below 7.4 MPa). However, at elevated temperature and pressure, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant conversion to the carbonate occurs. Extent of reaction is roughly 90% within 24 h, at 185 degrees C and partial pressure of CO{sub 2} (P{sub CO{sub 2}}) of 11.6 MPa. Current studies suggest that reaction kinetics can be improved by pretreatment of the mineral, catalysis of the reaction, and/or solution modification. Subsequent tests are intended to examine these options, as well as other mineral groups.
Date: January 1, 2000
Creator: O'Connor, W. K.; Dahlin, D. C.; Turner, P. C. & Walters, R.
System: The UNT Digital Library
Characterization for the Onset of Crystallization of Amorphous to Microcrystalline Silicon by Optical Spectroscopies (open access)

Characterization for the Onset of Crystallization of Amorphous to Microcrystalline Silicon by Optical Spectroscopies

We study the amorphous to microcrystalline silicon films made at three laboratories by using Raman, photoluminescence- and optical-abosrption spectroscopies.
Date: January 1, 2000
Creator: Yue, G.; Han, D.; Ganguly, G.; Wang, Q.; Yang, J. & Guha, S.
System: The UNT Digital Library
CHARACTERIZATION OF EPITAXIAL GROWTH OF SEMICONDUCTING RHENIUM ''DISILICIDE'' FILMS (open access)

CHARACTERIZATION OF EPITAXIAL GROWTH OF SEMICONDUCTING RHENIUM ''DISILICIDE'' FILMS

None
Date: January 1, 2000
Creator: Misra, A. & Verdier, M.
System: The UNT Digital Library
CO2 storage in solid form: a study of direct mineral carbonation (open access)

CO2 storage in solid form: a study of direct mineral carbonation

Direct mineral carbonation by an ex-situ process in an aqueous system has been investigated over the past two years. The process utilizes a slurry of water mixed with a magnesium silicate mineral, such as olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with sub- or supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3-. The H+ ion hydrolyzes the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. Results of the baseline tests, conducted on ground products of the natural minerals, have demonstrated that the kinetics of the reaction are slow at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm). However, at elevated temperature and pressure, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant conversion to the carbonate occurs. Extent of reaction is roughly 90% within 24 hours, at 185 C and partial pressure of CO2 (PCO2) of 115 atm. Heat pretreatment of the serpentine, coupled with bicarbonate and salt additions to the solution, improve reaction kinetics, resulting in an extent of reaction of roughly …
Date: January 1, 2000
Creator: O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Rush, G.E.; Walters, Richard P. & Turner, Paul C.
System: The UNT Digital Library
Comparison of 3D Maximum A Posteriori and Filtered Backprojection algorithms for high resolution animal imaging in microPET (open access)

Comparison of 3D Maximum A Posteriori and Filtered Backprojection algorithms for high resolution animal imaging in microPET

We have evaluated the performance of two three dimensional reconstruction algorithms with data acquired from microPET, a high resolution tomograph dedicated to small animal imaging. The first was a linear filtered-backprojection algorithm (FBP) with reprojection of the missing data and the second was a statistical maximum-aposteriori probability algorithm (MAP). The two algorithms were evaluated in terms of their resolution performance, both in phantoms and in vivo. Sixty independent realizations of a phantom simulating the brain of a baby monkey were acquired, each containing 3 million counts. Each of these realizations was reconstructed independently with both algorithms. The ensemble of the sixty reconstructed realizations was used to estimate the standard deviation as a measure of the noise for each reconstruction algorithm. More detail was recovered in the MAP reconstruction without an increase in noise relative to FBP. Studies in a simple cylindrical compartment phantom demonstrated improved recovery of known activity ratios with MAP. Finally in vivo studies also demonstrated a clear improvement in spatial resolution using the MAP algorithm. The quantitative accuracy of the MAP reconstruction was also evaluated by comparison with autoradiography and direct well counting of tissue samples and was shown to be superior.
Date: January 1, 2000
Creator: Chatziioannou, A.; Qi, J.; Moore, A.; Annala, A.; Nguyen, K.; Leahy, R. M. et al.
System: The UNT Digital Library
Comparison of Dye-Sensitized Rutile- and Anatase-Based TiO2 Solar Cells (open access)

Comparison of Dye-Sensitized Rutile- and Anatase-Based TiO2 Solar Cells

The objective of this work is to develop and optimize the new dye-sensitized solar cell technology. In view of the infancy of rutile material development for solar cells, the PV response of the dye-sensitized rutile-based solar cell is remarkably close to that of the anatase-based cell.
Date: January 1, 2000
Creator: Park, N. G.; van de Lagemaat, J. & Frank, A. J.
System: The UNT Digital Library
Competitive ancillary service procurement in California (open access)

Competitive ancillary service procurement in California

California has undertaken a major restructuring of its electricity utility sector. Most electricity is now sold in open markets operated by the PX and other entities. Bilateral contracting among some market participants is also permitted. A group of independent generating companies bids into these markets together with out of state resources. In addition to these markets, CAISO operates markets for both imbalance energy and AS, a quite unusual feature of the California system. These markets were initially quite chaotic and were rife with market power problems. However, various reforms have now created a system that functions well. During the restructuring process, special provisions were made to protect public purpose programs, including renewable generation.
Date: January 1, 2000
Creator: Marnay, Chris; Siddiqui, Afzal S. & Khavkin, Mark
System: The UNT Digital Library
A comprehensive landscape approach for monitoring bats on the Nevada Test Site in south-central Nevada (open access)

A comprehensive landscape approach for monitoring bats on the Nevada Test Site in south-central Nevada

The Nevada Test Site (NTS) is located in south-central Nevada and encompasses approximately 3,497 square kilometers (1,350 square miles). It straddles both the Mojave and Great Basin Deserts and includes a distinct transition region between these two deserts. Because of its geographical location, a great level of vegetative and physiographic diversity exists on the NTS. Also, numerous mines and tunnels are found on the NTS which are potential roost sites for bats. Multiple technqiues are being used to inventory and monitor the bat fauna on the NTS. These techniques include mistnetting at water sources with concurrent use of the Anabat II bat detection system, conducting road surveys with the Anabat II system, and conducting exit surveys at mine and tunnel entrances using the Anabat II system. To date, a total of 13 species of bats has been documented on the NTS, of which six are considered species of concern by the US Fish and Wildlife Service. These include Townsend's big-eared bat (Corynorhinus townsendii), spotted bat (Euderma maculatum), small-footed myotis (Myotis ciliolabrum), long-eared myotis (M. evotis), fringed myotis (M. thysanodes), and long-legged myotis (M. volans). Results from mistnet and Anabat surveys reveal that all bat species of concern except for the …
Date: January 1, 2000
Creator: Hall, D.
System: The UNT Digital Library
Copper in Contacts to CdTe (open access)

Copper in Contacts to CdTe

Cu from the back contact of a polycrystalline CdS/CdTe solar cell does more than assist in forming a low-resistance contact.
Date: January 1, 2000
Creator: Gessert, T. A.; Asher, S.; Narayanswamy, C. & Rose, D.
System: The UNT Digital Library
Cross-Section AFM and EFM Examination of Thin-Film Solar Cells (open access)

Cross-Section AFM and EFM Examination of Thin-Film Solar Cells

We demonstrated the feasibility of analyzing cross sections of thin-film CdTe/CdS and CIGS/CdS solar cells using atomic force microscopy (AFM).
Date: January 1, 2000
Creator: Moutinho, H. R.; Ballif, C.; Al-Jassim, M. M.; Dhere, R. G. & Kazmerski, L. L.
System: The UNT Digital Library