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High-resolution simulations and modeling of reshocked single-mode Richtmyer-Meshkov instability. I. Comparison to experimental data and to amplitude growth model predictions

Description: The reshocked single-mode Richtmyer-Meshkov instability is simulated in two spatial dimensions using the fifth- and ninth-order weighted essentially non-oscillatory shock-capturing method with uniform spatial resolution of 256 points per initial perturbation wavelength. The initial conditions and computational domain are modeled after the single-mode, Mach 1.21 air(acetone)/SF{sub 6} shock tube experiment of Collins and Jacobs [J. Fluid Mech. 464, 113 (2002)]. The simulation densities are shown… more
Date: May 15, 2006
Creator: Latini, M; Schilling, O & Don, W
Partner: UNT Libraries Government Documents Department
open access

Statistical characterization of dislocation ensembles

Description: We outline a method to study the spatial and orientation statistics of dynamical dislocation systems by modeling the dislocations as a stochastic fiber process. Statistical measures have been introduced for the density, velocity, and flux of dislocations, and the connection between these measures and the dislocation state and plastic distortion rate in the crystal is explained. A dislocation dynamics simulation model has been used to extract numerical data to study the evolution of these statis… more
Date: May 17, 2006
Creator: El-Azab, A.; Deng, J. & Tang, M.
Partner: UNT Libraries Government Documents Department
open access

Beyond Spin-Orbit: Probing Electron Correlation in the Pu 5f States

Description: Experiments planned to address the issue of electron correlation in the Pu 5f states are described herein. The key is the utilization of the Fano Effect, the observation of spin polarization in nonmagnetic systems, using chiral excitation such as circularly polarized X-rays.
Date: May 8, 2006
Creator: Tobin, J G
Partner: UNT Libraries Government Documents Department
open access

Melting of bcc Transition Metals and Icosahedral Clustering

Description: In contrast to polyvalent metals, transition metals have low melting slopes(dT/dP) that are due to partially filled d-bands that allow for a lowering of liquid phase energy through s-d electron transfer and the formation of local structures. In the case of bcc transition metals we show the apparent discrepancy of DAC melting measurements with shock melting of Mo can be understood by reexamining the shock data for V and Ta and introducing the presence of an icosahedral short range order (ISRO) m… more
Date: May 26, 2006
Creator: Ross, M; Boehler, R & Japel, S
Partner: UNT Libraries Government Documents Department
open access

Holographic Grand Unification

Description: No Description Available.
Date: May 7, 2006
Creator: Nomura, Yasunori; Poland, David & Tweedie, Brock
Partner: UNT Libraries Government Documents Department
open access

Towards an Accurate Performance Modeling of Parallel SparseFactorization

Description: We present a performance model to analyze a parallel sparseLU factorization algorithm on modern cached-based, high-end parallelarchitectures. Our model characterizes the algorithmic behavior bytakingaccount the underlying processor speed, memory system performance, aswell as the interconnect speed. The model is validated using theSuperLU_DIST linear system solver, the sparse matrices from realapplications, and an IBM POWER3 parallel machine. Our modelingmethodology can be easily adapted to stud… more
Date: May 26, 2006
Creator: Grigori, Laura & Li, Xiaoye S.
Partner: UNT Libraries Government Documents Department
open access

Mesoscale modeling of irreversible volume growth in powders of anisotropic crystals

Description: Careful thermometric analysis (TMA) on powders of micron-sized triamino-trinitrobenzene (TATB) crystallites are shown to display irreversible growth in volume when subjected to repeated cycles of heating and cooling. Such behavior is counter-intuitive to typical materials response to simulated annealing cycles in atomic-scale molecular dynamics. However, through coarse-grained simulations using a mesoscale Hamiltonian we quantitatively reproduce irreversible growth behavior in such powdered mat… more
Date: May 5, 2006
Creator: Gee, R.; Maiti, A. & Fried, L.
Partner: UNT Libraries Government Documents Department
open access

Transmission electron microscopy of actinide materials

Description: Actinide metallurgy, crystallography, physics, and chemistry are of great interest due to the unique behavior of the 5f states that dominate the electronic structure. The 5f states produce a wide range of fascinating behaviors in the actinide materials. from superconductivity to exotic magnetism. Accordingly, they are of great interest, but are difficult to work with. Transmission electron microscopy (TEM) can overcome many of the problems of working with actinide materials and can be used to i… more
Date: May 30, 2006
Creator: Moore, K
Partner: UNT Libraries Government Documents Department
open access

Target Plate Conditions During Stochastic Boundary Operation on DIII-D

Description: A major concern for large tokamaks like ITER is the presence of edge localized modes (ELMs) that repeatedly send large bursts of particles and heat into the divertor plates. Operation with resonant magnetic perturbations (RMP) at the boundary of DIII=D has suppressed ELMs for values of q95 {approx} 3.7. At the target plate, the conditions during ELM suppressed operation for both high and low collisionality are observed by a set of radially distributed Langmuir probes. At high collisionality (n*… more
Date: May 15, 2006
Creator: Watkins, J; Evans, T; Moyer, R; Lasnier, C & Rudakov, D
Partner: UNT Libraries Government Documents Department
open access

Experimental and Numerical Studies of Separatrix Splitting and Magnetic Footprints in DIII-D

Description: A numerical field line integration code is used to study the structure of divertor footprints produced by small non-axisymmetric magnetic perturbation in the DIII-D tokamak. The numerical modeling results are compared to experimental infrared camera data which show a splitting of the divertor target plate heat flux into several distinct peaks when an n=3 magnetic perturbation from the DIII-D I-coil is applied. The heat flux splitting consistently appears when the n=3 perturbation is applied and… more
Date: May 15, 2006
Creator: Evans, T; Joseph, I; Moyer, R; Fenstermacher, M; Lasnier, C & Yan, L
Partner: UNT Libraries Government Documents Department
open access

Application of the TraPPE force field to predicting isothermal pressure-volume curves at high pressures and high temperatures

Description: Knowledge of the thermophysical properties of materials at extreme pressure and temperature conditions is essential for improving our understanding of many planetary and detonation processes. Significant gaps in what is known about the behavior of materials at high density and high temperature exist, largely due to the limitations and dangers of performing experiments at the necessary extreme conditions. Modeling these systems through the use of equations of state and particle-based simulation … more
Date: May 19, 2006
Creator: Eggimann, B L; Siepmann, J I & Fried, L E
Partner: UNT Libraries Government Documents Department
open access

TOUGH+/GasH20 study of the effects of a heat source buried in theMartian permafrost

Description: We use TOUGH+/GasH2O to study the effects of a heat sourceburied in the Martian permafrost to evaluate the possibility ofestablishing a wet zone of liquid water, in which terrestrialmicroorganisms could survive and multiply. Analysis of the problemindicates that (1) only a limited permafrost volume (not exceeding 0.35 min radius) is affected, (2) a "wet" zone with limited amounts of liquidwater de-velops (not exceeding 8 and 0.7 kg for a 250 W and a 62.5 Wsource, respectively), (3) the wet zone… more
Date: May 12, 2006
Creator: Moridis, George J. & Pruess, Karsten
Partner: UNT Libraries Government Documents Department
open access

U.S. Aims for Zero-Energy: Support for PV on New Homes

Description: As a market segment for solar photovoltaic (PV) adoption, new homes have a number of attractive attributes. Homebuyers can easily roll the cost of the PV system into their mortgage and, with rebates or other financial incentives, potentially realize an immediate net positive cash flow from the investment. PV system performance can be optimized by taking roof orientation, shading, and other structural factors into account in the design of new homes. Building-integrated photovoltaics (BIPV), whic… more
Date: May 11, 2006
Creator: Barbose, Galen; Wiser, Ryan & Bolinger, Mark
Partner: UNT Libraries Government Documents Department
open access

Toroidally Asymmetric Distributions of Hydrocarbon (CD) Emission and Chemical Sputtering Sources in DIII-D

Description: Measurements in DIII-D show that the carbon chemical sputtering sources along the inner divertor and center post are toroidally periodic and highest at the upstream tile edge. Imaging with a tangentially viewing camera and visible spectroscopy were used to monitor the emission from molecular hydrocarbons (CH/CD) at 430.8 nm and deuterium neutrals in attached and partially detached divertors of low-confinement mode plasmas. In contrast to the toroidally periodic CD distribution, emission from de… more
Date: May 16, 2006
Creator: Groth, M.; Brooks, N. H.; Fenstermacher, M. E.; Lasnier, C. J.; McLean, A. G. & Watkins, J. G.
Partner: UNT Libraries Government Documents Department
open access

Tomographic wavefront correction for the LSST

Description: The Large Synoptic Survey Telescope (LSST) is a three mirror modified Paul-Baker design with an 8.4m primary, a 3.4m secondary, and a 5.0m tertiary followed by a 3-element refractive corrector producing a 3.5 degree field of view. This design produces image diameters of <0.3 arcsecond 80% encircled energy over its full field of view. The image quality of this design is sufficient to ensure that the final images produced by the telescope will be limited by the atmospheric seeing at an excelle… more
Date: May 3, 2006
Creator: Phillion, D. W.; Olivier, S. S.; Baker, K.; Seppala, L. & Hvisc, S.
Partner: UNT Libraries Government Documents Department
open access

Proteomic Analysis of Calcium- and Phosphorylation-dependentCalmodulin Complexes in Mammalian Cells

Description: Protein conformational changes due to cofactor binding (e.g. metal ions, heme) and/or posttranslational modifications (e.g. phosphorylation) modulate dynamic protein complexes. Calmodulin (CaM) plays an essential role in regulating calcium (Ca{sup 2+}) signaling and homeostasis. No systematic approach on the identification of phosphorylation-dependent Ca{sup 2+}/CaM binding proteins has been published. Herein, we report a proteome-wide study of phosphorylation-dependent CaM binding proteins fro… more
Date: May 26, 2006
Creator: Jang, Deok-Jin & Wang, Daojing
Partner: UNT Libraries Government Documents Department
open access

High-voltage-compatible, fully depleted CCDs

Description: We describe charge-coupled device (CCD) developmentactivities at the Lawrence Berkeley National Laboratory (LBNL).Back-illuminated CCDs fabricated on 200-300 mu m thick, fully depleted,high-resistivity silicon substrates are produced in partnership with acommercial CCD foundry.The CCDs are fully depleted by the application ofa substrate bias voltage. Spatial resolution considerations requireoperation of thick, fully depleted CCDs at high substrate bias voltages.We have developed CCDs that are c… more
Date: May 15, 2006
Creator: Holland, Stephen E.; Bebek, Chris J.; Dawson, Kyle S.; Emes, JohnE.; Fabricius, Max H.; Fairfield, Jessaym A. et al.
Partner: UNT Libraries Government Documents Department
open access

High Bandwidth Data Recording Systems for Pulsed Power and Laser Produced Plasma Experiments.

Description: We present two high bandwidth data transmission and recording systems for the measurement of transient signals during pulsed power and laser produced plasmas. These systems use fiber optic cables to transmit analog data over long distances to high bandwidth digitizing oscilloscopes. One system is based on the direct modulation of a laser diode and has a bandwidth of 1.5 GHz. The other system is based upon a fiber-optic Mach-Zehnder modulator and has a bandwidth of 12 GHz, and is limited by the … more
Date: May 2, 2006
Creator: May, M. J.; Clancy, T.; Fittinghoff, D.; Halvorson, C.; MIlls, T.; Nikitin, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Observation of amplification of a 1ps pulse by SRS of a 1 ns pulse in a plasma with conditions relevant to pulse compression

Description: The compression of a laser pulse by amplification of an ultra short pulse beam Which seeds the stimulated Raman scatter of the first beam has been long been discussed in the context of solid and gas media. We investigate the possibility of using intersecting beams in a plasma to compress nanosecond pulses to picosecond duration by scattering from driven electron waves. Recent theoretical studies have shown the possibility of efficient compression With large amplitude, non-linear Langmuir waves … more
Date: May 24, 2006
Creator: Kirkwood, R K; Dewald, E; Wilks, S C; Meezan, N; Niemann, C; Berger, R L et al.
Partner: UNT Libraries Government Documents Department
open access

Elastic Scattering of Low-Energy Electrons byTetrahydrofuran

Description: We present the results of ab initio calculations for elasticelectron scattering by tetrahydrofuran (THF) using the complex Kohnvariational method. We carried out fixed-nuclei calculations at theequilibrium geometry of the target molecule for incident electronenergies up to 20 eV. The calculated momentum transfer cross sectionsclearly reveal the presence of broad shape resonance behavior in the 8-10eV energy range, in agreement with recent experiments. The calculateddifferential cross sections a… more
Date: May 9, 2006
Creator: Trevisan, Cynthia S.; Orel, Ann E. & Rescigno, Thomas N.
Partner: UNT Libraries Government Documents Department
open access

The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot

Description: We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number… more
Date: May 10, 2006
Creator: Vomel, Christof; Tomov, Stanimire Z.; Wang, Lin-Wang; Marques,Osni A. & Dongarra, Jack J.
Partner: UNT Libraries Government Documents Department
open access

Simulations of liquid ribidium expanded to the critical density

Description: Quantum molecular dynamic simulations were used to examine the change in atomic and electronic structure in liquid rubidium along its liquid-vapor coexistence curve. Starting from the liquid at the triple point, with increasing expansion we observe a continuous increase in the electron localization leading to ion clustering near the metal-nonmetal transition at about twice the critical density, in agreement with electrical measurements, and to the presence of dimers near and below the critical … more
Date: May 16, 2006
Creator: Ross, M; Yang, L H & Pilgrim, W
Partner: UNT Libraries Government Documents Department
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