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Reduced Pressure Electron Beam Welding Evaluation Activities on a Ni-Cr-Mo Alloy for Nuclear Waste Packages

Description: The current waste package design for the proposed repository at Yucca Mountain Nevada, USA, employs gas tungsten arc welding (GTAW) in fabricating the waste packages. While GTAW is widely used in industry for many applications, it requires multiple weld passes. By comparison, single-pass welding methods inherently use lower heat input than multi-pass welding methods which results in lower levels of weld distortion and also narrower regions of residual stresses at the weld TWI Ltd. has developed… more
Date: September 11, 2003
Creator: Wong, F.; Punshon, C.; Dorsch, T.; Fielding, P.; Richard, D.; Yang, N. et al.
Item Type: Refine your search to only Article
open access

On Issues of Precision for Hardware-based Volume Visualization

Description: This paper discusses issues with the limited precision of hardware-based volume visualization. We will describe the compositing OVER operator and how fixed-point arithmetic affects it. We propose two techniques to improve the precision of fixed-point compositing and the accuracy of hardware-based volume visualization. The first technique is to perform dithering of color and alpha values. The second technique we call exponent-factoring, and captures significantly more numeric resolution than dit… more
Date: April 11, 2003
Creator: LaMar, E C
Item Type: Refine your search to only Article
open access

Re-Assessing the Maximum Allowed Infrared (IR) Power for Enchanced Layering in a Conduction Dominated Cryogenic NIF-Scale Hohlraum

Description: Recent measurements of the infrared (IR) absorption coefficient of CH and CD capsules differ significantly from earlier estimated values from thin flat samples. The optimum wavelength for IR enhanced layering of DT and D{sub 2} ice layers inside of a NIF scale hohlraum depends on the relative ice and capsule absorption coefficients. This update of a previous memo shows the maximum ice heating with IR as a function of ice and capsule absorption instead of at discrete wavelengths. Also discussed … more
Date: August 11, 2003
Creator: Kozioziemski, B J
Item Type: Refine your search to only Report
open access

Radiative Corrections to One-Photon Decays of Hydrogenic Ions

Description: Radiative corrections to the decay rate of n = 2 states of hydrogenic ions are calculated. The transitions considered are the M1 decay of the 2s state to the ground state and the E1(M2) decays of the 2p{sub 1/2} and 2p{sub 3/2} states to the ground state. The radiative corrections start in order {alpha}(Z{alpha}){sup 2}, but the method used sums all orders of Z{alpha}. The leading {alpha}(Z{alpha}){sup 2} correction for the E1 decays is calculated and compared with the exact result. The extensi… more
Date: November 11, 2003
Creator: Sapirstein, J; Pachucki, K & Cheng, K T
Item Type: Refine your search to only Article
open access

Investigate Methods to Decrease Compilation Time-AX-Program Code Group Computer Science R& D Project

Description: Large simulation codes can take on the order of hours to compile from scratch. In Kull, which uses generic programming techniques, a significant portion of the time is spent generating and compiling template instantiations. I would like to investigate methods that would decrease the overall compilation time for large codes. These would be methods which could then be applied, hopefully, as standard practice to any large code. Success is measured by the overall decrease in wall clock time a devel… more
Date: June 11, 2003
Creator: Cottom, T
Item Type: Refine your search to only Report
open access

Rates, Polarizations, and Asymmetries in Charmless Vector-Vector B Decays

Description: With a sample of approximately 89 million B{bar B} pairs collected with the BABAR detector, they measure branching fractions, determine the degree of longitudinal polarization, and search for direct CP violation in the decays B{sup 0} {yields} {phi}K*{sup 0} and B{sup +} {yields} {phi}K*{sup +}. They perform a search for other charmless vector-vector B decays involving {rho} and K*(892) resonances and observe the decays B{sup +} {yields} {rho}{sup 0} K*{sup +} and B{sup +} {yields} {rho}{sup 0}… more
Date: March 11, 2003
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Gaillard, J.-M.; Hicheur, A.; Karyotakis, Y. et al.
Item Type: Refine your search to only Article
open access

Effects of Spatial Variations in Packing Fraction of Reactor Physics Parameters in Pebble-Bed Reactors

Description: The well-known spatial variation of packing fraction near the outer boundary of a pebble-bed reactor core is cited. The ramifications of this variation are explored with the MCNP computer code. It is found that the variation has negligible effects on the global reactor physics parameters extracted from the MCNP calculations for use in analysis by diffusion-theory codes, but for local reaction rates the effects of the variation are naturally important. Included is some preliminary work in using … more
Date: June 11, 2003
Creator: Terry, W. K.; Ougouag, A. M.; Rahnema, F. & Mckinley, M. S.
Item Type: Refine your search to only Article
open access

On the Existence of Pathological Detonation Waves

Description: Pathological detonation waves with velocities greater than Chapman-Jouguet (C-J) have been proposed theoretically but never observed experimentally in gaseous, liquid or solid explosives. Two types of pathological chemical reaction zones have been identified within the Zeldovich-von Neumann-Doring (ZND) model: an exothermic chemical decomposition with a mole decrease during from the von Neumann spike state to the C-J state and an exothermic reaction followed by an endothermic reaction (eigenval… more
Date: July 11, 2003
Creator: Tarver, Craig M.
Item Type: Refine your search to only Article
open access

Large Diffractive Optics for GEo-Based Earth Surveillance

Description: The natural vantage point for performing Earth-centric operations from space is geosynchronous orbit (GEO); a platform there moves at the same rate as the Earth's surface, so appears to continually ''hover'' over a fixed site on the Earth. Unlike spacecraft in other orbits, which rapidly fly-over targets, a GEO-based platform remains in-position all the time. In order to insure continual access to sites using low earth orbit (LEO) platforms, one needs a large enough constellation ({approx} 50) … more
Date: September 11, 2003
Creator: Hyde, R A
Item Type: Refine your search to only Report
open access

Hydroacoustic Blockage Calibration for Discrimination

Description: The core focus of this hydroacoustic research is to develop a better understanding of hydroacoustic blockage to better predict those stations that can be used in discrimination analysis for any particular event. The research involves two approaches: (1) model-based assessment of blockage and (2) ground-truth data-based assessment of blockage. The goal is to reliably determine all hydroacoustic stations that can be brought to bear on a discrimination analysis from any event location in the world… more
Date: July 11, 2003
Creator: Harben, Philip E.; Matzel, Eric; Upton, Zachary & Pulli, Jay J.
Item Type: Refine your search to only Article
open access

Tests of the Contamination Analysis Unit, Phase 2

Description: Lawrence Livermore National Laboratory (LLNL) has developed a mass spectrometer-based system that measures organic surface residues in situ. This system, called the Contamination Analysis Unit (CAU), can detect and quantify a variety of volatile surface residues on a range of different substrates. Residue samples are removed from the substrate using a combination of vacuum and thermal desorption, and are then ionized and quantified by a quadrupole mass spectrometer. The current effort (Phase 2)… more
Date: September 11, 2003
Creator: Meltzer, Michael & Daley, Paul
Item Type: Refine your search to only Report
open access

Reference Artifacts for NDE

Description: Two reference artifacts will be fabricated for this study. One of the artifacts will have a cylindrical geometry and will contain features similar to those on an SNRT target. The second artifact will have a spherical geometry and will contain features similar to those on a Double Shell target. The artifacts were designed for manufacturability and to provide a range of features that can be measured using NDE methods. The cylindrical reference artifact is illustrated in Figure 1. This artifact co… more
Date: February 11, 2003
Creator: Bono, M.; Hibbard, R. & Martz, H. E.
Item Type: Refine your search to only Report
open access

Multiple Access in Ultra-Wideband Communications Using Multiple Pulses

Description: Multiple access (MA) in UWB communication is an area of active research. To date several time-division or code-division pulse amplitude modulation (PAM) or pulse position modulation (PPM) schemes have been proposed to separate multiple users in UWB communications. Conventionally, all users employ the same pulse shape and modulate the transmit pulse based on changing amplitude or position. One concern with using the same pulse for all channels is that the multiple access interference (MAI) incre… more
Date: April 11, 2003
Creator: Nekoogar, F. & Dowla, F.
Item Type: Refine your search to only Article
open access

Fragmentation, Merging, and Internal Dynamics for PIC Simulation with Finite Size Particles

Description: In plasma or rarified gas physics, collisions are rare but non-ignorable events. To model systems with arbitrary collisonality, it is necessary to start with a model that is fully capable of capturing collisionless, kinetic behavior. It is also necessary to build strategies to provide the essential economies into the scheme as collisions become more frequent. The desired model should progress smoothly and continuously from collisionless particle dynamics to collision-dominated fluid. We are dev… more
Date: August 11, 2003
Creator: Hewett, D. & Larson, D. J.
Item Type: Refine your search to only Article
open access

Edge Detection to Isolate Motion in Adaptive Optics Systems

Description: Adaptive optics uses signal processing techniques and deformable mirrors to minimize image degradation caused by phase aberrations. In the case of telescope imaging, the atmosphere causes phase aberrations. In the case of satellite imaging, errors due to the ultra-light-weight characteristics of the primary mirror cause phase aberrations. Scene-based Shack-Hartmann Wave Front Sensing takes the correlation between successive wavelets to determine these phase aberrations. A large problem with the… more
Date: July 11, 2003
Creator: Chan, C W
Item Type: Refine your search to only Report
open access

Loops in Reeb Graphs of 2-Manifolds

Description: Given a Morse function f over a 2-manifold with or without boundary, the Reeb graph is obtained by contracting the connected components of the level sets to points. We prove tight upper and lower bounds on the number of loops in the Reeb graph that depend on the genus, the number of boundary components, and whether or not the 2-manifold is orientable. We also give an algorithm that constructs the Reeb graph in time O(n log n), where n is the number of edges in the triangulation used to represen… more
Date: February 11, 2003
Creator: Cole-McLaughlin, K; Edelsbrunner, H; Harer, J; Natarajan, V & Pascucci, V
Item Type: Refine your search to only Article
open access

Pressure Wave Measurements Resulting from Thermal Cook-Off of the HMX Based High Explosive LX-04

Description: Experiments that investigate thermal and nearby explosion scenarios are needed to provide essential data to models for accurate predictions. A porous LX-04 (85/15 wt% HMX/Viton) sample was heated in a heavily confined donor charge until it thermally exploded. The reaction accelerated a steel cover plate across a 10 cm gap into a preheated gauged acceptor cylinder (near its theoretical maximum density) of LX-04. The carbon resistor gauges in the acceptor measured the resulting multi-dimensional … more
Date: July 11, 2003
Creator: Garcia, F.; Vandersall, K. S.; Forbes, J. W.; Tarver, Craig M. & Greenwood, D.
Item Type: Refine your search to only Article
open access

Composite Species in the Hydrodynamic Theory of Atomic Mixing in Multicomponent Partially Ionized Gases

Description: A dynamical description of atomic mixing in multicomponent gases and plasmas was summarized in a previous report (UCRL-ID-145502). That description is based on the use of separate continuity and momentum equations for each species present, including neutral atoms, ions, and free electrons. This level of detail is not always feasible in practical problems, where subsets of species (e.g., neutral atoms of a particular element together with their ionization products) must be grouped or lumped toge… more
Date: September 11, 2003
Creator: Ramshaw, J D
Item Type: Refine your search to only Report
open access

Development of High Power Lasers for Materials Interactions

Description: The Lawrence Livermore National Laboratory (LLNL) has a long history of developing high power lasers for use in basic science and applications. The Laser Science and Technology Program (LS&T) at LLNL supports advanced lasers and optics development both for the National Ignition Facility (NIF) as well as for high power lasers and optics technology for a broader range of government, military and industrial applications. The NIF laser is currently under construction with the first of the 192 b… more
Date: April 11, 2003
Creator: Hackel, L A
Item Type: Refine your search to only Article
open access

Feasibility Study on Using a Single Mixer Pump for Tank 241-AN-101 Waste Retrieval

Description: The objective of this evaluation was to determine whether a single rotating pump located 20 ft off-center would adequately mix expected AN-101 waste. Three-dimensional, AN-101 pump jet mixing simulation results indicate that a single, 20-ft off-centered mixer pump would mobilize almost all solids even at the furthest tank wall for sludge yield strength up to 150 Pa or less. Because the yield strength of the AN-101 waste was estimated to be less than 150 Pa, the AN-101 pump mixing model results … more
Date: February 11, 2003
Creator: Onishi, Yasuo; Wells, Beric E.; Yokuda, Satoru T. & Terrones, Guillermo
Item Type: Refine your search to only Report
open access

A Comparison of the Effect of Temperature on the Passivity Breakdown and Repassivation Potentials of Wrought and Welded Alloy 22 in 5 M CaC12

Description: The study of the electrochemical behavior of wrought and welded Alloy 22 was carried out in 5 M CaCl{sub 2} between 45 and 120 C. Comparisons were made between the electrochemical behaviors of the wrought and welded forms of Alloy 22 Multiple Crevice Assembly (MCA) specimens. The susceptibility to corrosion was found to increase with increase in temperature in both the wrought and the welded forms of the alloy. The weld metal was found to be less susceptible to localized corrosion under the con… more
Date: August 11, 2003
Creator: Ilevbrave, G
Item Type: Refine your search to only Article
open access

Progress in Long Scale Length Laser-Plasma Interactions

Description: The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneous… more
Date: November 11, 2003
Creator: Glenzer, S. H.; Arnold, P.; Bardsley, G.; Berger, R. L.; Bonanno, G.; Borger, T. et al.
Item Type: Refine your search to only Article
open access

Direct Observations of Phase Transitions in Ti-6Al-4V Alloy Transient Welds using Time Resolved X-Ray Diffraction

Description: Time Resolved X-Ray Diffraction (TRXRD) experiments were used to directly observe phase transformations occurring during gas tungsten arc spot welding of Ti-6Al-4V. These in-situ x-ray diffraction experiments tracked the evolution of the {alpha} {yields} {beta} {yields} L {yields} {beta} {yields} {alpha}/{alpha}{prime} phase transformation sequence in real time during rapid weld heating and cooling. Three different weld locations were examined, providing kinetic information about phase transfor… more
Date: November 11, 2003
Creator: Elmer, J. W.; Palmer, T. A.; Babu, S. S.; Zhang, W. & Debroy, T.
Item Type: Refine your search to only Article
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