UNT Libraries Government Documents Department - 117,460 Matching Results

Search Results

2020 Foresight Forging the Future of Lawrence Livermore National Laboratory

Description: 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.
Date: January 1, 2000
Creator: Chrzanowski, P.

2020 Vision Project Summary: FY99

Description: 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.
Date: January 2000
Creator: Gordon, K. W. & Scott, K. P.


Description: 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.).
Date: January 2000
Creator: Cunningham, G. S. & Lehovich, A.

Accelerated Strategic Computing Initiative (ASCI) Program Plan [FY2000]

Description: 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.
Date: January 2000


Description: 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.
Date: January 1, 2000
Creator: Berkovich, Adam J.

Advanced Fusion Power Plant Studies. Annual Report for 1999

Description: 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.
Date: January 1, 2000
Creator: Chan, V.S.; Chu, M.S.; Greenfield, C.M.; Kinsey, J.E. & al., et


Description: 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.
Date: January 1, 2000

Advanced high temperature superconductor film-based process using RABiTS

Description: 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).
Date: January 1, 2000
Creator: Goyal, A.; Hawsey, R.A.; Hack, J. & Moon, D.

Advanced laser diodes for sensing applications

Description: 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.
Date: January 1, 2000


Description: 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.
Date: January 1, 2000
Creator: Abbasian, Javad

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

Description: 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.

Alloy design of Nd

Description: 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.
Date: January 2000
Creator: Horton, J. A. & Herchenroeder, J. W.


Description: 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).
Date: January 1, 2000
Creator: Hurley, John S.

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

Description: 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.

Analysis of the radiation fallout tests at ETBS, France (Fall 1996)

Description: 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.
Date: January 1, 2000
Creator: Barnes, J.M. & Santoro, R.T.

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

Description: 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


Description: 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

Asynchronous parallel pattern search for nonlinear optimization

Description: 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
Date: January 1, 2000
Creator: Hough, P. D.; Kolda, T. G. & Torczon, V. J.