UNT Libraries Government Documents Department - 117,647 Matching Results

Search Results

Results: 1 - 50 next
3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI
No Description Available.
2020 Foresight Forging the Future of Lawrence Livermore National Laboratory
The Lawrence Livermore National Laboratory (LLNL) of 2020 will look much different from the LLNL of today and vastly different from how it looked twenty years ago. We, the members of the Long-Range Strategy Project, envision a Laboratory not defined by one program--nuclear weapons research--but by several core programs related to or synergistic with LLNL's national security mission. We expect the Laboratory to be fully engaged with sponsors and the local community and closely partnering with other research and development (R&D) organizations and academia. Unclassified work will be a vital part of the Laboratory of 2020 and will visibly demonstrate LLNL's international science and technology strengths. We firmly believe that there will be a critical and continuing role for the Laboratory. As a dynamic and versatile multipurpose laboratory with a national security focus, LLNL will be applying its capabilities in science and technology to meet the needs of the nation in the 21st century. With strategic investments in science, outstanding technical capabilities, and effective relationships, the Laboratory will, we believe, continue to play a key role in securing the nation's future.
2020 Vision Project Summary: FY99
During the 1998-99 school year, students from participating schools completed and submitted a variety of scenarios describing potential world and regional conditions in the year 2020 and their possible effect on U.S. national security. This report summarizes the student's views and describes trends observed over the course of the 2020 Vision project's four years.
4D RECONSTRUCTIONS FROM LOW-COUNT SPECT DATA USING DEFORMABLE MODELS WITH SMOOTH INTERIOR INTENSITY VARIATIONS
The Bayes Inference Engine (BIE) has been used to perform a 4D reconstruction of a first-pass radiotracer bolus distribution inside a CardioWest Total Artificial Heart, imaged with the University of Arizona's FastSPECT system. The BIE estimates parameter values that define the 3D model of the radiotracer distribution at each of 41 times spanning about two seconds. The 3D models have two components: a closed surface, composed of hi-quadratic Bezier triangular surface patches, that defines the interface between the part of the blood pool that contains radiotracer and the part that contains no radiotracer, and smooth voxel-to-voxel variations in intensity within the closed surface. Ideally, the surface estimates the ventricular wall location where the bolus is infused throughout the part of the blood pool contained by the right ventricle. The voxel-to-voxel variations are needed to model an inhomogeneously-mixed bolus. Maximum a posterior (MAP) estimates of the Bezier control points and voxel values are obtained for each time frame. We show new reconstructions using the Bezier surface models, and discuss estimates of ventricular volume as a function of time, ejection fraction, and wall motion. The computation time for our reconstruction process, which directly estimates complex 3D model parameters from the raw data, is performed in a time that is competitive with more traditional voxel-based methods (ML-EM, e.g.).
Accelerated Strategic Computing Initiative (ASCI) Program Plan [FY2000]
In August 1995, the United States took a significant step to reduce the nuclear danger. The decision to pursue a zero- yield Comprehensive Test Ban Treaty will allow greater control over the proliferation of nuclear weapons and will halt the growth of new nuclear systems. This step is only possible because of the Stockpile Stewardship Program, which provides an alternative means of ensuring the safety, performance, and reliability of the United States' enduring stockpile. At the heart of the Stockpile Stewardship Program is ASCI, which will create the high-confidence simulation capabilities needed to integrate fundamental science, experiments, and archival data into the stewardship of the actual weapons in the stockpile. ASCI will also serve to drive the development of simulation as a national resource by working closely with the computer industry and with universities.
ACTINYL(VI) SPECIATION IN CONCENTRATED SODIUM CHLORIDE SOLUTIONS
No Description Available.
ADVANCED DIRECT LIQUEFACTION CONCEPTS FOR PETC GENERIC UNITS
The results of Laboratory and Bench-Scale experiments and supporting technical and economic assessments conducted under DOE Contract No. DE-AC22-91PC91040 is reported for the period October 1, 1999 to December 31, 1999. This contract is with the University of kentucky Research Foundation, which supports work with the University of Kentucky Center for Applied Energy Researc, CONSOL, Inc., LDP Associates, and Hydrocarbon Technologies, Inc. This work involves the introduction into the basic two-stage liquefaction process several novel concepts, which include dispersed lower-cost catalysts, coal cleaning by oil agglomeration, and distillate hydrotreating and dewaxing. This project has been modified to include an investigation into the production of value added materials from coal using liquefaction based technologies.
Advanced Fusion Power Plant Studies. Annual Report for 1999
Significant progress in physics understanding of the reversed shear advanced tokamak regime has been made since the last ARIES-RS study was completed in 1996. The 1999 study aimed at updating the physics design of ARIES-RS, which has been renamed ARIES-AT, using the improved understanding achieved in the last few years. The new study focused on: Improvement of beta-limit stability calculations to include important non-ideal effects such as resistive wall modes and neo-classical tearing modes; Use of physics based transport model for internal transport barrier (ITB) formation and sustainment; Comparison of current drive and rotational flow drive using fast wave, electron cyclotron wave and neutral particle beam; Improvement in heat and particle control; Integrated modeling of the optimized scenario with self-consistent current and transport profiles to study the robustness of the bootstrap alignment, ITB sustainment, and stable path to high beta and high bootstrap fraction operation.
ADVANCED GAS TURBINE SYSTEMS RESEARCH
The activities of the Advanced Gas Turbine Systems Research (AGRSR) program are described in the quarterly report. The report is divided into discussions of Membership, Administration, Technology Transfer (Workshop/Education) and Research. Items worthy of note are presented in extended bullet format following the appropriate heading.
Advanced high temperature superconductor film-based process using RABiTS
The purpose of this Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Research Corporation (Contractor), Managing contractor for Oak Ridge National Laboratory (ORNL) and Midwest Superconductivity, Inc. (MSI) and Westinghouse Science and Electric Company (WEC) was to develop the basis for a commercial process for the manufacturing of superconducting tape based on the RABiTS technology developed at ORNL. The chosen method for deposition of YBCO films on RABiTS was Metal Organic chemical Vapor Deposition (MOCVD).
Advanced laser diodes for sensing applications
The authors have developed diode lasers for short pulse duration and high peak pulse power in the 0.01--100.0 m pulsewidth regime. A primary goal of the program was producing up to 10 W while maintaining good far-field beam quality and ease of manufacturability for low cost. High peak power, 17 W, picosecond pulses have been achieved by gain switching of flared geometry waveguide lasers and amplifiers. Such high powers area world record for this type of diode laser. The light emission pattern from diode lasers is of critical importance for sensing systems such as range finding and chemical detection. They have developed a new integrated optical beam transformer producing rib-waveguide diode lasers with a symmetric, low divergence, output beam and increased upper power limits for irreversible facet damage.
ADVANCED SORBENT DEVELOPMENT
The overall objective of this program was to develop regenerable sorbents for use in the temperature range of 343 to 538 C (650 to 1000 F) to remove hydrogen sulfide (H{sub 2}S) from coal-derived fuel gases in a fluidized-bed reactor. The goal was to develop sorbents that are capable of reducing the H{sub 2}S level in the fuel gas to less than 20 ppmv in the specified temperature range and pressures in the range of 1 to 20 atmospheres, with chemical characteristics that permit cyclic regeneration over many cycles without a drastic loss of activity, as well as physical, characteristics that are compatible with the fluidized bed application. This topical report focuses on the investigation directed toward preparation of zinc-based sorbents using the sol-gel approach that has been shown to require only a moderate temperature for calcination, while resulting in significantly more attrition-resistant sorbents. The sorbents prepared in this part of the investigation and the results from their evaluation in packed-bed and fluidized-bed reactors are described in this report.
AGE-RELATED CHANGES IN PU DEDUCED FROME XAFS DATA WITH A NEW SUPER-RESOLUTION FAST FOURIER TRANSFORM
No Description Available.
Los Alamos Plutonium Facility Waste Management System
No Description Available.
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.
Alloy design of Nd
This report summarizes the results of research conducted as part of CRADA ORNL94-0279 between Oak Ridge National Laboratory and Magnequench International, Inc. The objective was to gain a better understanding of the fracture process in the rare earth based permanent magnets in order to possibly improve the mechanical properties of these inherently brittle intermetallics. The first part of the study established a technique for measuring a critical property, fracture toughness, and surveying currently available commercial material made by a number of different processes.
ALTERNATING CURRENT LOSSES IN AG-SHEATHED BSCCO (2212 AND 2223) TAPES AND WIRES AND YBCO (123) COATED CONDUCTORS
In this study, we focus on the examination of ac losses in conductors utilizing Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O [BSCCO (2223)] high TC superconductors (HTS). In addition, we seek to assist other facilities such as the University of Wisconsin-Madison Applied Superconductivity Center (UW-ASC), Brookhaven National Laboratory, and other DoE facilities investigating the use of HTS in electric power applications (e.g., generators, motors, and transformers). To accomplish this we will develop an ac losses capability at Clark Atlanta University to complement the established ac losses efforts at Brookhaven National Laboratory (BSCCO) on BSCCO/Ag and various material characterization efforts taking place at the UW-ASC. Our goal is through this effort to gain a greater understanding of the effects on ac losses due to parameters such as ac/dc current, J{sub c}, tape geometry, voltage tap placement, field orientation, material anisotropy, surface irregularities, percolations and filament coupling effects. As a result, we expect to better understand how to minimize ac losses in applications requiring real or practical conductors. HTS conductors based on BSCCO-2223 are now being routinely produced in industrial lengths of high quality. Vendors such as Southwire and ASC are producing multi-filamentary tapes in lengths of 6 km or more carrying critical current densities of up to 3 kA/cm**2 at 77 K. While this is approaching the level of performance where some large-scale applications are considered to be economically viable, a number of problems remain to be solved. The remaining issues include: rapid reduction in JC in magnetic fields; and power dissipation due to varying magnetic fields or currents (ac losses).
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.
Analysis of the radiation fallout tests at ETBS, France (Fall 1996)
A series of experiments were carried out at the Etablissement Technique de Bourges (ETBS), France to measure protection factors for the Russian T72M tank during exposure to gamma radiation emanating from the ground. The purpose of these measurements was to determine the reduction in the dose rate to the tank occupants when the vehicle traverses terrain that has been contaminated as the result of fallout from a nuclear weapon or when the ground has been contaminated by the distribution of radioactive material by terrorists. This report summarizes results of calculations that replicate the measurements. Comparisons of measured and calculated protection factors are reported for a series of nested iron cylinders and the T72M tank. The cylinder measurements were performed to compare protection factors measured at Bourges with those obtained previously at the US Army Aberdeen Test Center.
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.
APPLICATION OF FUZZY SET THEORY FOR EXPOSURE CONTROL IN BERYLLIUM PART MANUFACTURING
No Description Available.
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.
Asynchronous parallel pattern search for nonlinear optimization
Parallel pattern search (PPS) can be quite useful for engineering optimization problems characterized by a small number of variables (say 10--50) and by expensive objective function evaluations such as complex simulations that take from minutes to hours to run. However, PPS, which was originally designed for execution on homogeneous and tightly-coupled parallel machine, is not well suited to the more heterogeneous, loosely-coupled, and even fault-prone parallel systems available today. Specifically, PPS is hindered by synchronization penalties and cannot recover in the event of a failure. The authors introduce a new asynchronous and fault tolerant parallel pattern search (AAPS) method and demonstrate its effectiveness on both simple test problems as well as some engineering optimization problems
AUTOMATED DECONTAMINATION OF NUCLEAR MATERIAL CONTAINERS AT LOS ALAMOS NATIONAL LABORATORY
No Description Available.
AVATAR -- Adaptive Visualization Aid for Touring And Recovery
This document provides a report on the initial development of software which uses a standard visualization tool to determine, label and display salient regions in large 3D physics simulation datasets. This software uses parallel pattern recognition behind the scenes to handle the huge volume of data. This software is called AVATAR (Adaptive Visualization Aid for Touring and Recovery). It integrates approaches to gathering labeled training data, learning from large training sets utilizing parallelism and the final display of salient data in unseen visualization data sets. The paper uses vorticity fields for a large-eddy simulation to illustrate the method.
Ballistic Missile Silo Door Monitoring Analysis
This paper compares the cost and effectiveness of several potential options that may be used to monitor silo-based ballistic missiles. Silo door monitoring can be used to verify that warheads removed to deactivate or download silo-based ballistic missiles have not been replaced. A precedent for monitoring warhead replacement using reentry vehicle on site inspections (RV-OSIs) and using satellites has been established by START-I and START-II. However, other monitoring options have the potential to be less expensive and more effective. Three options are the most promising if high verification confidence is desired: random monitoring using door sensors; random monitoring using manned or unmanned aircraft; and continuous remote monitoring using unattended door sensors.
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.
BENCH-SCALE DEMONSTRATION OF HOT-GAS DESULFURIZATION TECHNOLOGY
No Description Available.
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.
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.
Biomass power for rural development. Quarterly report for the period July 1, 1999 - September 30, 1999
No Description Available.
Biomass power for rural development. Quarterly report, October 1, 1999 - December 31,1999
No Description Available.
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.''
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 eight index reaches. The utility of using index reaches to monitor trends in juvenile bull trout and brook trout relative abundance was assessed in the Warm Springs R. for the second year. Mean relative densities of both species, within the index reaches was slightly higher than what was observed in a 2.4 km control reach. Mill Creek was surveyed for the presence of juvenile bull trout. The American Fisheries Society ''Interim protocol for determining bull trout presence'' methodology was field tested. No bull trout were found in the 2 km survey area.
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 conditions include: 155?C; PCO2=185 atm; 15% solids. Under these conditions, 78% conversion of the silicate to the carbonate was achieved in 30 minutes. Future studies are intended to investigate various mineral pretreatment options, the carbonation solution characteristics, alternative reactants, scale-up to a continuous process, geochemical modeling, and process economics.
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 at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185?C and a partial pressure of CO2 (PCO2) of 115 atm. Recent tests using a bicarbonate solution, under identical …
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.
Cetaceans, Sea Turtles and Seabirds in the Northern Gulf of Mexico: Distribution, Abundance and Habitat Associations, Volume 1: Executive Summary
This report covers three years of research on the distribution and number of whales, dolphins, sea turtles, and sea birds in the Gulf of Mexico.
Cetaceans, Sea Turtles and Seabirds in the Northern Gulf of Mexico: Distribution, Abundance and Habitat Associations, Volume 2: Technical Report
The main purpose of this report covers three years of research on the distribution and number of whales, dolphins, sea turtles, and sea birds in the Gulf of Mexico. Volume two contains the technical report, going into the details and findings of the research.
Cetaceans, Sea Turtles and Seabirds in the Northern Gulf of Mexico: Distribution, Abundance and Habitat Associations, Volume 3: Data Appendix
The main purpose of this report covers three years of research on the distribution and number of whales, dolphins, sea turtles, and sea birds in the Gulf of Mexico. Volume three contains an appendix of all the available data.
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.
CHARACTERIZATION OF EPITAXIAL GROWTH OF SEMICONDUCTING RHENIUM ''DISILICIDE'' FILMS
No Description Available.
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.
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.
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 80% within 0.5 hours, at 155 C and PCO2 of 185 atm. Subsequent tests are intended to examine various pretreatment options, the carbonation solution characteristics, as well as other mineral groups.
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.
Compact Single-Stage Fuel Processor for PEM Fuel Cells. Final report
Based on observations during the steam reforming of ethanol, the authors conclude that carbon was forming in the steam generator due to the thermal decomposition of ethanol. Since ethanol is being thermally decomposed, they were operating the steam generator at too high of a temperature. The thermal degradation of ethanol was confirmed by using a GC with a flame ionization detector. They observed trace amounts of additional hydrocarbons other than methane in the effluent which we assume maybe ethane and ethylene. We identified the operating conditions that allowed us to steam reform ethanol for an acceptable amount of time. These conditions were a steam temperature of 200 C and a wall temperature of 400 C at the center of the reactor. The calculated ratios of CO{sub 2}/CO indicate that we can lower the potential for carbon deposition from the Boudouard further by reducing the pressure.
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.
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.
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.
Back to Top of Screen