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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.
Object Type:
Article
System:
The UNT Digital Library
Bio-Terrorism Threat and Casualty Prevention
The bio-terrorism threat has become the ''poor man's'' nuclear weapon. The ease of manufacture and dissemination has allowed an organization with only rudimentary skills and equipment to pose a significant threat with high consequences. This report will analyze some of the most likely agents that would be used, the ease of manufacture, the ease of dissemination and what characteristics of the public health response that are particularly important to the successful characterization of a high consequence event to prevent excessive causalities.
Date:
January 1, 2000
Creator:
NOEL,WILLIAM P.
Object Type:
Report
System:
The UNT Digital Library
Biomass power for rural development. Quarterly report for the period July 1, 1999 - September 30, 1999
None
Date:
January 1, 2000
Creator:
Cooper, James T.
Object Type:
Report
System:
The UNT Digital Library
Biomass power for rural development. Quarterly report, October 1, 1999 - December 31,1999
None
Date:
January 1, 2000
Creator:
Cooper, James T.
Object Type:
Report
System:
The UNT Digital Library
Biomass stakeholder views and concerns: Environmental groups and some trade association
This exploratory study of the views and concerns of 25 environmental organizations found high interest and concern about which biomass feedstocks would be used and how these biomass materials would be converted to energy. While all favored renewable energy over fossil or nuclear energy, opinion diverged over whether energy crops, residues, or both should be the primary source of a biomass/bioenergy fuel cycle. About half of the discussants favored biomass ``in general'' as a renewable energy source, while the others were distributed about equally over five categories, from favor-with-conditions, uncertain, skeptical, opposed, to ``no organizational policy.''
Date:
January 1, 2000
Creator:
Peelle, E.
Object Type:
Report
System:
The UNT Digital Library
Bull Trout Distribution and Abundance in the Waters on and Bordering the Warm Springs Indian Reservation, 2000 Annual Report.
The range of bull trout (Salvelinus confluentus) in the Deschutes River basin has decreased from historic levels due to many factors including dam construction, habitat degradation, brook trout introduction and eradication efforts. While the bull trout population appears to be stable in the Metolius River-Lake Billy Chinook system they have been largely extirpated from the upper Deschutes River (Buchanan et al. 1997). Little was known about bull trout in the lower Deschutes basin until BPA funded project No.9405400 began during 1998. In this progress report we describe the findings from the third year (2000) of the multi-year study aimed at determining the life history, genetics, habitat needs and limiting factors of bull trout in the lower Deschutes subbasin. Juvenile bull trout and brook trout (Salvelinus fontinalis) relative abundance was assessed in the Warm Springs River and Shitike Creek by night snorkeling. In the Warm Springs R. juvenile bull trout were slightly more numerous than brook trout, however, both were found in low densities. Relative densities of both species declined from 1999 observations. Juvenile bull trout vastly out numbered brook trout in Shitike Cr. Relative densities of juvenile bull trout increased while brook trout abundance was similar to 1999 observations in …
Date:
January 1, 2000
Creator:
Brun, Christopher
Object Type:
Report
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
CHARACTERIZATION OF EPITAXIAL GROWTH OF SEMICONDUCTING RHENIUM ''DISILICIDE'' FILMS
None
Date:
January 1, 2000
Creator:
Misra, A. & Verdier, M.
Object Type:
Article
System:
The UNT Digital Library
Chemistry of the heaviest elements--one atom at a time
In keeping with the goal of the Viewpoint series of the Journal of Chemical Education, this article gives a 75-year perspective of the chemistry of the heaviest elements, including a 50-year retrospective view of past developments, a summary of current research achievements and applications, and some predictions about exciting, new developments that might be envisioned within the next 25 years. A historical perspective of the importance of chemical separations in the discoveries of the transuranium elements from neptunium (Z=93) through mendelevium (Z=101) is given. The development of techniques for studying the chemical properties of mendelevium and still heavier elements on the basis of measuring the radioactive decay of a single atom (''atom-at-a-time'' chemistry) and combining the results of many separate experiments is reviewed. The influence of relativistic effects (expected to increase as Z{sup 2}) on chemical properties is discussed. The results from recent atom-at-a-time studies of the chemistry of the heaviest elements through seaborgium (Z=106) are summarized and show that their properties cannot be readily predicted based on simple extrapolation from the properties of their lighter homologues in the periodic table. The prospects for extending chemical studies to still heavier elements than seaborgium are considered and appear promising.
Date:
January 1, 2000
Creator:
Hoffman, Darleane C. & Lee, Diana M.
Object Type:
Report
System:
The UNT Digital Library
Cleburne Times-Review (Cleburne, Tex.), Ed. 1 Saturday, January 1, 2000
Daily newspaper from Cleburne, Texas that includes local, state, and national news along with advertising.
Date:
January 1, 2000
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Closed-loop biomass co-firing. Quarterly technical progress report for the period October - December 1999
Tasks included the following: analyze data from small plot harvests; large-scale planting of high-fiber cane variety; pilot-scale testing of fuel blends; procuring harvest equipment; perform harvest and co-firing trials for full-scale demonstration.
Date:
January 1, 2000
Creator:
Jakeway, Lee & Nakahata, Mae
Object Type:
Report
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
Collaborative Research: Hydrogeological-Geophysical Methods for Subsurface Site Characterization - Final Report
This research contributes three newly-developed relationships that significantly improve aquifer characterization: (1) a general relationship between total and channel porosities, (2) a general relationship between electrical resistivity and channel porosity, and (3) bounds on the electrical resistivity - seismic velocity relationship.
Date:
January 1, 2000
Creator:
Mavko, G.
Object Type:
Report
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
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
Object Type:
Article
System:
The UNT Digital Library
The Complete Fast Fourier Transform and Cascaded Transition-Band Filters to Reduce the Noise of Deconvolution
A measurement system's components: cabling, delay line, waveform recorder, etc., degrade acquired signals and their respective bandlimited frequency responses. Compensation software corrects for this frequency-dependent spectral degradation by deconvolving the transfer function of the entire measurement system out of the measured signal spectra. This report describes methods to transfer the characteristics of a wide bandwidth repetitive sampling oscilloscope to a single-shot transient digitizer, characterize the measurement system, develop a cascaded transition-band filter, and compensate data acquired with the filtered, characterized measurement system. These procedures are easily implemented, execute quickly, and successfully compensate waveforms possessing endpoint discontinuities. Waveforms possessing endpoint discontinuities are made to appear duration-limited and continuous. The spectra for these modified waveforms are correct, including at dc. The deconvolution process introduces unavoidable noise. Filtering is applied to reduce the deconvolution noise while minimally affecting compensated waveform risetime and amplitude. Resultant compensated data retains its initial dc baseline offset with improved waveform fidelity and low noise of deconvolution.
Date:
January 1, 2000
Creator:
Patterson, P.E.
Object Type:
Report
System:
The UNT Digital Library
Composite electrodes for advanced electrochemical applications. Quarterly report for the period October 1, - December 31, 1999
The electrochemical industry is one of the most highly energy intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating costs, and the proprietary nature of the technology. In addition, DSAs experience problems that include: contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from underattack, generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.
Date:
January 1, 2000
Creator:
Kovach, Chris
Object Type:
Report
System:
The UNT Digital Library
Composite wire plasma formation and evolution
The detailed understanding of the formation and evolution of plasma from rapidly heated metallic wires is a long-standing challenge in the field of plasma physics and in exploding wire engineering. This physical process is made even more complicated if the wire material is composed of a number of individual layers. The authors have successfully developed both optical and x-ray backlighting diagnostics. In particular, the x-ray backlighting technique has demonstrated the capability for quantitative determination of the plasma density over a wide range of densities. This diagnostic capability shows that the process of plasma formation is composed of two separate phases: first, current is passed through a cold wire and the wire is heated ohmically, and, second, the heated wire evolves gases that break down and forms a low-density plasma surrounding the wire.
Date:
January 1, 2000
Creator:
Spielman, Rick B.
Object Type:
Report
System:
The UNT Digital Library
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.
Object Type:
Article
System:
The UNT Digital Library
Computer-specific metrics for the regulation and load following ancillary services
In competitive electricity markets, the costs for each ancillary service should be charged to those who cause the costs to be incurred with charges based on the factors that contribute to these costs. For example, the amount of generating capacity assigned to the regulation service is a function of the short-term volatility of system load. Therefore, the charges for regulation should be related to the volatility of each load, not to its average demand. This report discusses the economic efficiency and equity benefits of assessing charges on the basis of customer-specific costs (rather than the traditional billing determinants, MWh or MW), focusing on two key real-power ancillary services, regulation and load following. The authors determine the extent to which individual customers and groups of customers contribute to the system's generation requirements for these two services. In particular, they analyze load data to determine whether some customers account for shares of these two services that differ substantially from their shares of total electricity consumption.
Date:
January 1, 2000
Creator:
Kirby, B. & Hirst, E.
Object Type:
Report
System:
The UNT Digital Library