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Spheromak formation studies in SSPX

Description: We present results from the Sustained Spheromak Physics Experiment (SSPX) at LLNL, which has been built to study energy confinement in spheromak plasmas sustained for up to 2 ms by coaxial DC helicity injection. Peak toroidal currents as high as 600kA have been obtained in the 1m dia. (0.23m minor radius) device using injection currents between 200-400kA; these currents generate edge poloidal fields in the range of 0.2-0.4T. The internal field and current profiles are inferred from edge field m… more
Date: September 29, 2000
Creator: Hill, D. N.; Bulmer, R. H.; Cohen, B. L.; Hooper, E. B.; LoDestro, L. L.; Mattor, N. et al.
Partner: UNT Libraries Government Documents Department
open access

A Sequential Fluid-mechanic Chemical-kinetic Model of Propane HCCI Combustion

Description: We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as inp… more
Date: November 29, 2000
Creator: Aceves, S M; Flowers, D L; Martinez-Frias, J; Smith, J R; Westbrook, C; Pitz, W et al.
Partner: UNT Libraries Government Documents Department
open access

FAUST observations of ultraviolet sources in the directions of NGC 4038-39 and 6752

Description: This article discusses an analysis of ultraviolet observations with the FAUST shuttle-borne telescope toward the Antennae and NGC 6752 celestial regions resulting in the detection of 46 and 221 candidate sources respectively, for a signal-to-noise ratio of 8.
Date: December 29, 2000
Creator: Daniels, Julian; Brosch, Noah; Almoznino, Elchanan; Shemmer, Ohad; Bowyer, Stuart & Lampton, Michael
Partner: UNT College of Arts and Sciences
open access

Effect of Extrusion Temperature on the Microstructural Development of Powder Metallurgy Ti-47A1-2Cr-1Nb-1Ta Alloy

Description: Effect of extrusion temperatures on the microstructural development of a powder metallurgy (PM) Ti-47Al-2Cr-1Nb-1Ta (at. %) alloy has been investigated. Microstructure of the PM alloy extruded at 1150 C consists of a fine-grained ({gamma} + {alpha}{sub 2}) two-phase structure in association with coarse grains of metastable B2 (ordered bcc) phase. In addition, fine {omega} (ordered hexagonal) particles are also found within some B2 grains. The PM alloy containing the metastable B2 grains display… more
Date: June 29, 2000
Creator: Hsiung, L. & Nieh, T.G.
Partner: UNT Libraries Government Documents Department
open access

Waste In-Situ Stabilization/Entombment Research and Development Project

Description: The technical basis and stakeholder acceptance of entombment technology is necessary before entombment becomes a decontamination and decommissioning (D and D) option for nuclear reactors. The authors present a research and development (R and D) approach addressing technical basis and stakeholder acceptance of entombment technology. The approach includes a consortium and the conceptual R and D program.
Date: August 29, 2000
Creator: Vernon, D.K.; Birk, S.M. & Hanson, R.G.
Partner: UNT Libraries Government Documents Department
open access

A Portable System for Nuclear, Chemical Agent and Explosives Identification

Description: The FRIS/PINS hybrid integrates the LLNL-developed Field Radionuclide Identification System (FRIS) with the INEEL-developed Portable Isotopic Neutron Spectroscopy (PINS) chemical assay system to yield a combined general radioisotope, special nuclear material, and chemical weapons/explosives detection and identification system. The PINS system uses a neutron source and a high-purity germanium {gamma}-ray detector. The FRIS system uses an electrochemically cooled germanium detector and its own an… more
Date: September 29, 2000
Creator: Parker, W. E.; Buckley, W. M.; Kreek, S. A.; Caffrey, A. J.; Mauger, G. J.; Lavietes, A. D. et al.
Partner: UNT Libraries Government Documents Department
open access

Gamma Attribute Measurements - Pu300, Pu600, Pu900

Description: Gamma rays are ideal probes for the determination of information about the special nuclear material that is in the transparency regime. Gamma rays are good probes because they interact relatively weakly with the containers that surround the SNM under investigation. In addition, gamma rays carry a great deal of information about the material under investigation. We have leveraged these two characteristics to develop three technologies that have proven useful for the measurements of various attri… more
Date: June 29, 2000
Creator: Luke, S.J. & Archer, D.E.
Partner: UNT Libraries Government Documents Department
open access

Numerical Results for Antiproton - Hydrogen Atom Scattering

Description: A great variety of numerical methods have been employed to solve the Schroedinger equation, the basic equation of theoretical atomic physics. Being a three body problem, the scattering of an incoming antiproton (p{sup -}) by a hydrogen atom (H, consisting of an electron, e{sup -}, bound to a proton, p) is one of the simplest problems in field of atomic theory that requires a numerical solution. Described and compared here are three methods, valid in essentially separate energy ranges from zero … more
Date: September 29, 2000
Creator: Morgan, D. L.
Partner: UNT Libraries Government Documents Department
open access

Constructing Material Interfaces from Data Sets with Volume-Fraction Information

Description: We present a new algorithm for material boundary interface reconstruction from data sets containing volume fractions. We transform the reconstruction problem to a problem that analyzes the dual data set, where each vertex in the dual mesh has an associated barycentric coordinate tuple that represents the fraction of each material present. After constructing the dual tetrahedral mesh from the original mesh, we construct material boundaries by mapping a tetrahedron into barycentric space and calc… more
Date: March 29, 2000
Creator: Bonnell, K.; Duchaineau, M. A.; Schikore, D. R.; Hamann, B. & Joy, K. I.
Partner: UNT Libraries Government Documents Department
open access

An Experimental Investigation of a Prescription for Identifying Plastic Strain

Description: A series of experiments is described in which a novel prescription for the identification of plastic strain is tested to determine its validity in the context of the strain-space formulation of rate-independent plasticity. Biaxial experiments were performed on several thin-walled aluminum 1100-O cylindrical specimens.
Date: February 29, 2000
Creator: Brown, A. A.; Casey, J. & Nikkel, D. J.
Partner: UNT Libraries Government Documents Department
open access

Profiling users in the UNIX os environment

Description: This paper presents results obtained by using a method of profiling a user based on the login host, the login time, the command set, and the command set execution time of the profiled user. It is assumed that the user is logging onto a UNIX host on a computer network. The paper concentrates on two areas: short-term and long-term profiling. In short-term profiling the focus is on profiling the user at a given session where user characteristics do not change much. In long-term profiling, the dura… more
Date: September 29, 2000
Creator: Dao, V N P; Vemuri, R & Templeton, S J
Partner: UNT Libraries Government Documents Department
open access

Distinct element modeling of the drift scale test

Description: A drift-scale distinct element model (DSDE) is being used to analyze geomechanical behavior in the Drift Scale Test (DST) now underway at Yucca Mountain, Nevada. The DST is a large-scale, long-term thermal test designed to investigate coupled thermal-mechanical-hydrological-chemical behavior in a fractured, welded tuff rock mass. Electric heaters are being used to heat a 50 m length of drift for 4 years, followed by 4 years of cooling. The target drift wall temperature is 200 C during much of t… more
Date: September 29, 2000
Creator: Blair, S. C.; Carlson, S. R. & Wagoner, J. L.
Partner: UNT Libraries Government Documents Department
open access

Dense Matter Characterization by X-ray Thomson Scattering

Description: We discuss the extension of the powerful technique of Thomson scattering to the x-ray regime for providing an independent measure of plasma parameters for dense plasmas. By spectrally-resolving the scattering, the coherent (Rayleigh) unshifted scattering component can be separated from the incoherent Thomson component, which is both Compton and Doppler shifted. The free electron density and temperature can then be inferred from the spectral shape of the high frequency Thomson scattering compone… more
Date: December 29, 2000
Creator: Landen, O. L.; Glenzer, S. H.; Edwards, M. J.; Lee, R. W.; Collins, G. W.; Cauble, R. C. et al.
Partner: UNT Libraries Government Documents Department
open access

Characterization of oxynitride dielectric films grown in NO/O{sub 2} mixtures by rapid thermal oxynitridation

Description: Ultra-thin oxynitride films were grown on Si by direct rapid thermal processing (RTP) oxynitridation in NO/O{sub 2} ambients with NO concentrations from 5% to 50%. During oxynitridation, nitrogen accumulated at the Si/dielectric interface and the average concentration of in N through the resulting films ranged from 0.3 to 3.0 atomic percent. The average concentration of N in the films increased with increasing NO in the ambient gas, but decreased with longer RTP times. The maximum N concentrati… more
Date: February 29, 2000
Creator: Everist, Sarah C.; Meisenheimer, Timothy L.; Nelson, Gerald C. & Smith, Paul Martin
Partner: UNT Libraries Government Documents Department
open access

Analytic Models of High-Temperature Hohlraums

Description: A unified set of high-temperature-hohlraum models has been developed. For a simple hohlraum, P{sub s} = [A{sub s}+(1{minus}{alpha}{sub W})A{sub W}+A{sub H}]{sigma}T{sub R}{sup 4} + (4V{sigma}/c)(dT{sub R}{sup r}/dt) where P{sub S} is the total power radiated by the source, A{sub s} is the source area, A{sub W} is the area of the cavity wall excluding the source and holes in the wall, A{sub H} is the area of the holes, {sigma} is the Stefan-Boltzmann constant, T{sub R} is the radiation brightnes… more
Date: November 29, 2000
Creator: Stygar, W. A.; Olson, R. E.; Spielman, R. B. & Leeper, R. J.
Partner: UNT Libraries Government Documents Department
open access

Wind tunnel tests of two airfoils for wind turbines operating at high reynolds numbers

Description: The objectives of this study were to verify the predictions of the Eppler Airfoil Design and Analysis Code for Reynolds numbers up to 6 x 106 and to acquire the section characteristics of two airfoils being considered for large, megawatt-size wind turbines. One airfoil, the S825, was designed to achieve a high maximum lift coefficient suitable for variable-speed machines. The other airfoil, the S827, was designed to achieve a low maximum lift coefficient suitable for stall-regulated machines. B… more
Date: June 29, 2000
Creator: Sommers, D. & Tangler, J.
Partner: UNT Libraries Government Documents Department
open access

Development of reference materials for SNF NDA systems

Description: The Department of Energy has over 200 different fuel types which will be placed in a geologic repository for ultimate disposal. At the present time, DOE EM is responsible for assuring safe existing conditions, achieving interim storage, and preparing for final disposition. Each task is governed by regulations which dictate a certain degree of knowledge regarding the contents and condition of the fuel. This knowledge and other associated characteristics are referred to as data needs. It is the s… more
Date: February 29, 2000
Creator: Klann, R. T.
Partner: UNT Libraries Government Documents Department
open access

Recordkeeping in the decommissioning process

Description: In the US, there are two sets of key decommissioning records clearly identified -- those that are essential for planning the D and D of a facility and then those that are the result of the decommissioning process itself. In some cases, the regulatory authorities require and in others advise the licensees of the records that may be useful or which are required to be kept from the decommissioning. In the remainder of the paper, the author attempts to highlight some important aspects of decommissi… more
Date: February 29, 2000
Creator: Boing, L. E.
Partner: UNT Libraries Government Documents Department
open access

Economics of grid-connected small wind turbines in the domestic market

Description: Exploitation of certain niche markets for small wind turbines is one strategy that could help speed the commercialization of grid-connected small turbines. The authors review the world's turbine manufacturers, the utility grid-connected applications and selected niche markets for grid-connected small wind systems (0.1 to 100 kilowatts). Wind turbine installation and purchase are handled under three different payment scenarios: paid in full up front, paid through a second mortgage, or paid as pa… more
Date: June 29, 2000
Creator: Forsyth, T.; Tu, P. & Gilbert, J.
Partner: UNT Libraries Government Documents Department
open access

Tensile instabilities for porous plasticity models

Description: Several concepts (and assumptions) from the literature for porous metals and ceramics have been synthesized into a consistent model that predicts an admissibility limit on a material's porous yield surface. To ensure positive plastic work, the rate at which a yield surface can collapse as pores grow in tension must be constrained.
Date: February 29, 2000
Creator: BRANNON,REBECCA M.
Partner: UNT Libraries Government Documents Department
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