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Verification & Validation: Goals, Methods, Levels, and Metrics

Description: This work briefly summarizes the current status of the V and V Program at LLNL regarding goals, methods, timelines, and issues for Verification and Validation (V and V) with Uncertainty Quantification (UQ). The goals are to evaluate various V and V methods, to apply them to computational simulation analyses, and integrate them into methods for Quantitative Certification techniques for the nuclear stockpile. Methods include qualitative and quantitative V and V processes with numerical values for… more
Date: April 29, 2003
Creator: Logan, R W & Nitta, C K
Partner: UNT Libraries Government Documents Department
open access

A Mortar Segment-to-Segment Frictional Contact Method for Large Deformations

Description: Contact modeling is still one of the most difficult aspects of nonlinear implicit structural analysis. Most 3D contact algorithms employed today use node-on-segment approaches for contacting dissimilar meshes. Two pass node-on-segment contact approaches have the well known deficiency of locking due to over constraint. Furthermore, node-on-segment approaches suffer when individual nodes slide out of contact at contact surface boundaries or when contacting nodes slide from facet to facet. This ca… more
Date: October 29, 2003
Creator: Puso, M & Laursen, T
Partner: UNT Libraries Government Documents Department
open access

Observations of Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Spot Welds Using Time Resolved X-Ray Diffraction

Description: Time Resolved X-Ray Diffraction (TRXRD) measurements are made in the Heat Affected Zone (HAZ) of 2205 Duplex Stainless Steel (DSS) spot welds. Both the {gamma} {yields} {delta} and {delta} {yields} {gamma} transformations are monitored as a function of time during the rapid spot weld heating and cooling cycles. These observations are then correlated with calculated thermal cycles. Where the peak temperatures are highest ({approx}1342 C), the {gamma} {yields} {delta} transformation proceeds to c… more
Date: October 29, 2003
Creator: Palmer, T.; Elmer, J. & Babu, S.
Partner: UNT Libraries Government Documents Department
open access

Linear and Nonlinear Wave Propagation in Negative Refraction Meta-materials

Description: We discuss linear and nonlinear optical wave propagation in a left-handed medium (LHM) or medium of negative refraction (NRM). We use the approach of characterizing the medium response totally by a generalized electric polarization (with a dielectric permittivity {tilde {var_epsilon}}(w, {rvec k})) that can be decomposed into a curl and a non-curl part. The description has a one-to-one correspondence with the usual approach characterizing the LHM response with a dielectric permittivity {var_eps… more
Date: May 29, 2003
Creator: Agranovich, V.M.; Shen, Y.R.; Baughman, R.H. & Zakhidov, A.A.
Partner: UNT Libraries Government Documents Department
open access

Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations

Description: We report a spin-unrestricted density functional theory (DFT) solution at the symmetric dimer structure for cluster models of Si(100). With this solution, it is shown that the symmetric structure is a minimum on the DFT potential energy surface, although higher in energy than the buckled structure. In restricted DFT calculations the symmetric structure is a saddle point connecting the two buckled minima. To further assess the effects of electron correlation on the relative energies of symmetric… more
Date: August 29, 2003
Creator: Jung, Yousung; Shao, Yihan; Gordon, Mark S.; Doren, Douglas J. & Head-Gordon, Martin
Partner: UNT Libraries Government Documents Department
open access

Computational economy improvements in PRISM

Description: The PRISM piecewise solution mapping procedure, in which the solution of the chemical kinetic ODE system is parameterized with quadratic polynomials, is applied to CFD simulations of H{sub 2}+air combustion. Initial cost of polynomial construction is expensive, but it is recouped as the polynomial is reused. We present two methods that help us to parameterize only in places that will ultimately have high reuse. We also implement non-orthogonal Gosset factorial designs, that reduce polynomial co… more
Date: January 29, 2003
Creator: Tonse, Shaheen R. & Brown, Nancy J.
Partner: UNT Libraries Government Documents Department
open access

Effects of Scatter Modeling on Time-Activity Curves Estimated Directly From Dynamic SPECT Projections

Description: Quantitative analysis of uptake and washout of cardiac single photon emission computed tomography (SPECT) radiopharmaceuticals has the potential to provide better contrast between healthy and diseased tissue, compared to conventional reconstruction of static images. Previously, we used B-splines to model time-activity curves (TACs) for segmented volumes of interest and developed fast least-squares algorithms to estimate spline TAC coefficients and their statistical uncertainties directly from d… more
Date: October 29, 2003
Creator: Reutter, Bryan W.; Gullberg, Grant T. & Huesman, Ronald H.
Partner: UNT Libraries Government Documents Department
open access

Fracture and fatigue resistance of Mo-Si-B alloys for ultrahigh-temperature structural applications

Description: Fracture and fatigue-crack growth properties are examined for a series of Mo-Mo3Si-Mo5SiB2 containing alloys, which utilize a continuous a-Mo matrix to achieve unprecedented room-temperature fracture resistance (>20 MPaAm). Mechanistically, these properties are explained in terms of toughening by crack trapping and crack bridging by the more ductile a-Mo phase.
Date: August 29, 2003
Creator: Kruzic, J. J.; Schneibel, J. H. & Ritchie, R. O.
Partner: UNT Libraries Government Documents Department
open access

A week of SRI 2003 in San Francisco

Description: The Eighth International Conference on Synchrotron Radiation (SRI 2003) ended its August 25-28 run at the Yerba Buena Center for the Arts in San Francisco with almost as many in attendance as at the beginning. The steady attendance was surely a tribute to the quality of the program and the excitement it generated among the more than 700 registrants who gathered for four days of plenary talks, parallel sessions, and posters, as well as facility tours of the ALS and SSRL on August 29.
Date: September 29, 2003
Creator: Robinson, Art
Partner: UNT Libraries Government Documents Department
open access

Towards increased policy relevance in energy modeling

Description: Historically, most energy models were reasonably equipped to assess the impact of a subsidy or change in taxation, but are often insufficient to assess the impact of more innovative policy instruments. We evaluate the models used to assess future energy use, focusing on industrial energy use. We explore approaches to engineering-economic analysis that could help improve the realism and policy relevance of engineering-economic modeling frameworks. We also explore solutions to strengthen the poli… more
Date: July 29, 2003
Creator: Worrell, Ernst; Ramesohl, Stephan & Boyd, Gale
Partner: UNT Libraries Government Documents Department
open access

Observation of Microwave Induced Zero-Conductance State in Corbino Rings of a Two-Dimensional Electron System

Description: Using Corbino samples they have observed oscillatory dc conductance in a high-mobility two-dimensional electron system when it is subjected to crossed microwave and magnetic fields. At the strongest of the oscillation minima the conductance is found to be vanishingly small, indicating a macroscopic insulating state associated with this minimum. With increasing voltage bias, a crossover from Ohmic to electron-heating regime is observed.
Date: August 29, 2003
Creator: Yang, C. L.; Pfeiffer, M. A.; Knuttila, T. A.; Du, R. R.; Pfeiffer,, L. N. & West, K. W.
Partner: UNT Libraries Government Documents Department
open access

Signatures of special nuclear material: High-energy gamma rays following fission

Description: Since September 11, 2001, much effort has been devoted to the development of new and improved means for the detection and prevention of the clandestine transport of special nuclear material (SNM, i.e. {sup 235}U or {sup 239}Pu) and other materials for producing weapons of mass destruction. In a recent Brief Communication, Borozdin et al. showed that cosmic-ray muons could be used to image dense objects inside containers. Here we describe a method for unequivocally identifying SNM in large seago… more
Date: May 29, 2003
Creator: Norman, Eric B.; Prussin, Stanley G.; Larimer, Ruth-Mary; Shugart, Howard; Browne, Edgardo; Smith, Alan R. et al.
Partner: UNT Libraries Government Documents Department
open access

Strategies for gas production from hydrate accumulations under various geologic conditions

Description: In this paper we classify hydrate deposits in three classes according to their geologic and reservoir conditions, and discuss the corresponding production strategies. Simple depressurization appears promising in Class 1 hydrates, but its appeal decreases in Class 2 and Class 3 hydrates. The most promising production strategy in Class 2 hydrates involves combinations of depressurization and thermal stimulation, and is clearly enhanced by multi-well production-injection systems. The effectiveness… more
Date: April 29, 2003
Creator: Moridis, G. & Collett, T.
Partner: UNT Libraries Government Documents Department
open access

Imaging of CO{sub 2} injection during an enhanced-oil-recovery experiment

Description: A series of time-lapse seismic cross well and single well experiments were conducted in a diatomite reservoir to monitor the injection of CO{sub 2} into a hydrofracture zone, using P- and S-wave data. During the first phase the set of seismic experiments were conducted after the injection of water into the hydrofrac-zone. The set of seismic experiments was repeated after a time period of 7 months during which CO{sub 2} was injected into the hydrofractured zone. The issues to be addressed ranged… more
Date: April 29, 2003
Creator: Gritto, Roland; Daley, Thomas M. & Myer, Larry R.
Partner: UNT Libraries Government Documents Department
open access

Use of Modeling for the Prevention of Solids Formation During Canyon Processing of Legacy Nuclear Materials at the Savannah River Site

Description: The Savannah River Site (SRS) Environmental Management (EM) nuclear material stabilization program includes the dissolution and processing of legacy materials from various DOE sites. The SRS canyon facilities were designed to dissolve and process spent nuclear fuel and targets. As the processing of typical materials is completed, unusual and exotic nuclear materials are being targeted for stabilization. These unusual materials are often difficult to dissolve using historical flowsheet condition… more
Date: January 29, 2003
Creator: Rhodes, W. D.
Partner: UNT Libraries Government Documents Department
open access

Mercury in Fish from a Sulfate-Amended Wetland Mesocosm

Description: This study used an experimental model of a constructed wetland to evaluate the risk of mercury methylation when the soil is amended with sulfate. The model was planted with Schoenoplectus californicus, and the sediments were varied during construction to provide a control and two levels of sulfate treatment.
Date: May 29, 2003
Creator: Harmon, S.M.
Partner: UNT Libraries Government Documents Department
open access

Measurement of the t{bar t} cross section at {radical}s = 1.96 TeV

Description: A measurement of the t{bar t} cross section at {radical}s = 1.96 TeV is carried out on data samples of {approx}40 pb{sup -1} in dilepton channels (e{mu}, ee and {mu}{mu}) and lepton+jets channels using two complementary approaches: a fully topological analysis and a soft-muon-tag. Overall, 17 events are observed with an expected background of 6.5 {+-} 0.6. This excess corresponds to an observation probability of three standard deviations and the measured t{bar t} cross section is: {sigma}{sub p… more
Date: July 29, 2003
Creator: al., Victor Abazov et
Partner: UNT Libraries Government Documents Department
open access

Towards a new LHC interaction region design for a luminosity upgrade

Description: After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the low-{beta} insertions with a higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. Preliminary studies show that, with magnet technology that is expected to be developed by early in the next decade, a factor of 2 to 5 reduction in {beta}* could be achieved with new insertions, as part of … more
Date: May 29, 2003
Creator: al., James Strait et
Partner: UNT Libraries Government Documents Department
open access

Characterizing emerging industrial technologies in energy models

Description: Conservation supply curves are a common tool in economic analysis. As such, they provide an important opportunity to include a non-linear representation of technology and technological change in economy-wide models. Because supply curves are closely related to production isoquants, we explore the possibility of using bottom-up technology assessments to inform top-down representations of energy models of the U.S. economy. Based on a recent report by LBNL and ACEEE on emerging industrial technolo… more
Date: July 29, 2003
Creator: Laitner, John A.; Worrell, Ernst; Galitsky, Christina & Hanson, Donald A.
Partner: UNT Libraries Government Documents Department
open access

An unsplit, cell-centered Godunov method for ideal MHD

Description: We present a second-order Godunov algorithm for multidimensional, ideal MHD. Our algorithm is based on the unsplit formulation of Colella (J. Comput. Phys. vol. 87, 1990), with all of the primary dependent variables centered at the same location. To properly represent the divergence-free condition of the magnetic fields, we apply a discrete projection to the intermediate values of the field at cell faces, and apply a filter to the primary dependent variables at the end of each time step. We tes… more
Date: August 29, 2003
Creator: Crockett, Robert K.; Colella, Phillip; Fisher, Robert T.; Klein, Richard I. & McKee, Christopher F.
Partner: UNT Libraries Government Documents Department
open access

Repackaging of Two Bulged Crimp Sealed Cans Containing Plutonium Bearing Materials

Description: Two cans containing plutonium bearing materials were found during radiography surveillance activities to be bulged. The cans had been stored in DOT 6M shipping containers at the Savannah River Site. The material in the first can (Item CZA96-179) was packaged can/bag/can configuration with the inner and outer cans being crimp sealed. The crimp sealed innermost can was clearly deformed from the radiography picture taken for surveillance purposes. This material had been stored in the shipping cont… more
Date: April 29, 2003
Creator: Watkins, R. W.
Partner: UNT Libraries Government Documents Department
open access

Novel integrated CMOS pixel structures for vertex detectors

Description: Novel CMOS active pixel structures for vertex detector applications have been designed and tested. The overriding goal of this work is to increase the signal to noise ratio of the sensors and readout circuits. A large-area native epitaxial silicon photogate was designed with the aim of increasing the charge collected per struck pixel and to reduce charge diffusion to neighboring pixels. The photogate then transfers the charge to a low capacitance readout node to maintain a high charge to voltag… more
Date: October 29, 2003
Creator: Kleinfelder, Stuart; Bieser, Fred; Chen, Yandong; Gareus, Robin; Matis, Howard S.; Oldenburg, Markus et al.
Partner: UNT Libraries Government Documents Department
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