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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

Similarity-Guided Streamline Placement with Error Evaluation

Description: Most streamline generation algorithms either provide a particular density of streamlines across the domain or explicitly detect features, such as critical points, and follow customized rules to emphasize those features. However, the former generally includes many redundant streamlines, and the latter requires Boolean decisions on which points are features (and may thus suffer from robustness problems for real-world data). We take a new approach to adaptive streamline placement for steady vector… more
Date: August 15, 2007
Creator: Chen, Y.; Cohen, J. D. & Krolik, J. H.
Partner: UNT Libraries Government Documents Department
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Increasing FTIR spectromicroscopy speed and resolution through compressive imaging

Description: At the Advanced Light Source at Lawrence Berkeley National Laboratory, we are investigating how to increase both the speed and resolution of synchrotron infrared imaging. Synchrotron infrared beamlines have diffraction-limited spot sizes and high signal to noise, however spectral images must be obtained one point at a time and the spatial resolution is limited by the effects of diffraction. One technique to assist in speeding up spectral image acquisition is described here and uses compressive … more
Date: October 15, 2007
Creator: Gallet, Julien; Riley, Michael; Hao, Zhao & Martin, Michael C
Partner: UNT Libraries Government Documents Department
open access

Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

Description: Among the olivine-structured metal phosphate family, LiMnPO{sub 4} exhibits a high discharge potential (4V), which is still compatible with common electrolytes, making it interesting for use in the next generation of Li ion batteries. The extremely low electronic conductivity of this material severely limits its electrochemical performance, however. One strategy to overcome this limitation is to make LiMnPO{sub 4} nanoparticulate to decrease the diffusion distance. Another is to add a carbon or… more
Date: May 15, 2008
Creator: Chen, Jiajun; Doeff, Marca M. & Wang, Ruigang
Partner: UNT Libraries Government Documents Department
open access

Analysis of Injection-Induced Micro-Earthquakes in a Geothermal Steam Reservoir, The Geysers Geothermal Field, California

Description: In this study we analyze relative contributions to the cause and mechanism of injection-induced micro-earthquakes (MEQs) at The Geysers geothermal field, California. We estimated the potential for inducing seismicity by coupled thermal-hydrological-mechanical analysis of the geothermal steam production and cold water injection to calculate changes in stress (in time and space) and investigated if those changes could induce a rock mechanical failure and associated MEQs. An important aspect of th… more
Date: May 15, 2008
Creator: Rutqvist, Jonny; Rutqvist, J. & Oldenburg, C.M.
Partner: UNT Libraries Government Documents Department
open access

An Implicit "Drift-Lorentz" Particle Mover for Plasma and Beam Simulations

Description: In order to efficiently perform particle simulations in systems with widely varying magnetization, we developed a drift-Lorentz mover, which interpolates between full particle dynamics and drift kinetics in such a way as to preserve a physically correct gyroradius and particle drifts for both large and small ratios of the timestep to the cyclotron period. In order to extend applicability of the mover to systems with plasma frequency exceeding the cyclotron frequency such as one may have with fu… more
Date: July 15, 2008
Creator: Friedman, A.; Grote, D. P.; Vay, J. L. & Cohen, R. H.
Partner: UNT Libraries Government Documents Department
open access

Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

Description: Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic con… more
Date: March 15, 2008
Creator: Seol, Yongkoo & Javandel, Iraj
Partner: UNT Libraries Government Documents Department
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2007 Plant Metabolic Engineering Gordon Conference and Graduate Research Seminar

Description: Plant Metabolic Engineering is an emerging field that integrates a diverse range of disciplines including plant genetics, genomics, biochemistry, chemistry and cell biology. The Gordon-Kenan Graduate Research Seminar (GRS) in Plant Metabolic Engineering was initiated to provide a unique opportunity for future researcher leaders to present their work in this field. It also creates an environment allowing for peer-review and critical assessment of work without the intimidation usually associated … more
Date: September 15, 2008
Creator: Grotewold, Erich
Partner: UNT Libraries Government Documents Department
open access

Evaluation of production samples of the scintillators LaBr3:Ce and LaCl3:Ce

Description: We report on the evaluation of the performance of two recently developed scintillator materials, LaCl{sub 3}:Ce and LaBr{sub 3}:Ce, at the task of gamma ray spectroscopy. Their performance is compared to a standard scintillator used for gamma ray spectroscopy--a 25 mm diameter 25 mm tall cylinder of NaI:Tl. We measure the pulse height, energy resolution, and full-energy efficiency of production LaBr{sub 3}:Ce and LaCl{sub 3}:Ce scintillation crystals of different sizes and geometries for a vari… more
Date: September 15, 2005
Creator: Choong, Woon-Seng; Derenzo, Stephen E. & Moses, William W.
Partner: UNT Libraries Government Documents Department
open access

PREDICTION OF CHARACTERISTIC LENGTH AND FRACTURE TOUGHNESS IN DUCTILE-BRITTLE TRANSITION

Description: Finite element method was used to analyze the three-point bend experimental data of A533B-1 pressure vessel steel obtained by Sherry, Lidbury, and Beardsmore [1] from -160 to -45 C within the ductile-brittle transition regime. As many researchers have shown, the failure stress ({sigma}{sub f}) of the material could be approximated as a constant. The characteristic length, or the critical distance (r{sub c}) from the crack tip, at which {sigma}{sub f} is reached, is shown to be temperature depen… more
Date: April 15, 2008
Creator: Lam, P
Partner: UNT Libraries Government Documents Department
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Spatial resolution limits for synchrotron-based infrared spectromicroscopy

Description: Detailed spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source synchrotron facility in Berkeley, CA. The high-brightness synchrotron source is coupled at this beamline to a Thermo-Electron Continumum XL infrared microscope. Two types of resolution tests in both the mid-IR (using a KBr beamsplitter and an MCT-A* detector) and in the near-IR (using a CaF2 beamsplitter and an InGaAS detector) were performed and compared to a simple diffraction-limited spot size mod… more
Date: October 15, 2007
Creator: Levenson, Erika; Lerch, Philippe & Martin, Michael C.
Partner: UNT Libraries Government Documents Department
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Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars

Description: Where Martian rocks have been exposed to liquid water, chemistry versus depth profiles could elucidate both Martian climate history and potential for life. The persistence of primary minerals in weathered profiles constrains the exposure time to liquid water: on Earth, mineral persistence times range from {approx}10 ka (olivine) to {approx}250 ka (glass) to {approx}1Ma (pyroxene) to {approx}5Ma (plagioclase). Such persistence times suggest mineral persistence minima on Mars. However, Martian so… more
Date: March 15, 2008
Creator: Steefel, Carl; Hausrath, E. M.; Navarre-Sitchler, A. K.; Sak, P. B.; Steefel, C. & Brantley, S. L.
Partner: UNT Libraries Government Documents Department
open access

Localized or Systemic {italic In Vivo} Heat-Inactivation of Human Immunodeficiency Virus (HIV): A Mathematical Analysis

Description: Temperatures as low as 42 C, maintained for a little as 25 minutes, inactivate {approx}25% of HIV. Furthermore, human immunodeficiency virus (HIV)-infected T-cells are more sensitive to heat than healthy lymphocytes and susceptibility increases when the cells are pre-sensitized by exposure to tumor necrosis factor. Thus, induction of a whole-body hyperthermia, or hyperthermia specifically limited to tissues having a high viral load, are potential antiviral therapies for acquired immunodeficienc… more
Date: December 15, 1993
Creator: Pennypacker, Carl R.; Perelson, A.S.; Nys, N.; Nelson, G. & Sessler, D.I.
Partner: UNT Libraries Government Documents Department
open access

Sugar-mediated semidian oscillation of gene expression in the cassava storage root regulates starch synthesis

Description: Starch branching enzyme (SBE) activity in the cassava storage root exhibited a diurnal fluctuation, dictated by a transcriptional oscillation of the corresponding SBE genes. The peak of SBE activity coincided with the onset of sucrose accumulation in the storage, and we conclude that the oscillatory mechanism keeps the starch synthetic apparatus in the storage root sink in tune with the flux of sucrose from the photosynthetic source. When storage roots were uncoupled from the source, SBE expres… more
Date: January 15, 2008
Creator: Jansson, Christer; Baguma, Yona; Sun, Chuanxin; Boren, Mats; Olsson, Helena; Rosenqvist, Sara et al.
Partner: UNT Libraries Government Documents Department
open access

Ground Penetrating Radar in Hydrogeophysics

Description: To meet the needs of a growing population and to provide us with a higher quality of life, increasing pressures are being placed on our environment through the development of agriculture, industry, and infrastructures. Soil erosion, groundwater depletion, salinization, and pollution have been recognized for decades as major threats to ecosystems and human health. More recently, the progressive substitution of fossil fuels by biofuels for energy production and climate change have been recognized… more
Date: January 15, 2008
Creator: Hubbard, Susan; Lambot, S.; Binley, A.; Slob, E. & Hubbard, S.
Partner: UNT Libraries Government Documents Department
open access

The continental margin is a key source of iron to the HNLC North Pacific Ocean

Description: Here we show that labile particulate iron and manganese concentrations in the upper 500m of the Western Subarctic Pacific, an iron-limited High Nutrient Low Chlorophyll (HNLC) region, have prominent subsurface maxima between 100-200 m, reaching 3 nM and 600 pM, respectively. The subsurface concentration maxima in particulate Fe are characterized by a more reduced oxidation state, suggesting a source from primary volcagenic minerals such as from the Kuril/Kamchatka margin. The systematics of the… more
Date: January 15, 2008
Creator: Lam, P. J. & Bishop, J. K. B
Partner: UNT Libraries Government Documents Department
open access

Electrokinetic Power Generation from Liquid Water Microjets

Description: Although electrokinetic effects are not new, only recently have they been investigated for possible use in energy conversion devices. We have recently reported the electrokinetic generation of molecular hydrogen from rapidly flowing liquid water microjets [Duffin et al. JPCC 2007, 111, 12031]. Here, we describe the use of liquid water microjets for direct conversion of electrokinetic energy to electrical power. Previous studies of electrokinetic power production have reported low efficiencies (… more
Date: February 15, 2008
Creator: Duffin, Andrew M. & Saykally, Richard J.
Partner: UNT Libraries Government Documents Department
open access

Measurement of the Decay B- to D*0 e- anti-nu_e

Description: Using 226 million B{bar B} events recorded on the {Upsilon}(4S) resonance with the BABAR detector at the SLAC e{sup +}e{sup -} PEP-II storage rings, they reconstruct B{sup -} {yields} D*{sup 0}e{sup -}{bar {nu}}{sub e} decays using the decay chain D*{sup 0} {yields} D{sup 0}{pi}{sup 0} and D{sup 0} {yields} K{sup -} {pi}{sup +}. From the dependence of their differential rate on the w, the dot product of the four-velocities of B{sup -} and D*{sup 0}, and using the form factor description by Capr… more
Date: January 15, 2008
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department
open access

Comparing FRACHEM and TOUGHREACT for reactive transport modelingof brine-rock interactions in enhanced geothermal systems (EGS)

Description: Coupled modelling of fluid flow and reactive transport ingeothermal systems is challenging because of reservoir conditions such ashigh temperatures, elevated pressures and sometimes high salinities ofthe formation fluids. Thermal hydrological-chemical (THC) codes, such asFRACHEM and TOUGHREACT, have been developed to evaluate the long-termhydrothermal and chemical evolution of exploited reservoirs. In thisstudy, the two codes were applied to model the same geothermal reservoir,to forecast reser… more
Date: November 15, 2005
Creator: Andre, L.; Spycher, N.; Xu, T.; Pruess, K. & Vuataz, F.-D.
Partner: UNT Libraries Government Documents Department
open access

Promising X-ray fluorescence tests for superconducting tunneljunction detector

Description: Scientists in the Physical Biosciences Division of the Ernest Orlando Berkeley National Laboratory (Berkeley Lab) studying transition metals in proteins with fluorescence-detected L-edge absorption spectroscopy have found the measurements to be extremely challenging. The difficulty is that the metal centers are present in very dilute concentrations so that their weak fluorescence is often obscured by strong background signals carbon and oxygen. To solve this problem, the Berkeley group has been… more
Date: May 15, 2001
Creator: Friedrich, Stephan & Robinson, Arthur L.
Partner: UNT Libraries Government Documents Department
open access

LUsim: A Framework for Simulation-Based Performance Modelingand Prediction of Parallel Sparse LU Factorization

Description: Sparse parallel factorization is among the most complicated and irregular algorithms to analyze and optimize. Performance depends both on system characteristics such as the floating point rate, the memory hierarchy, and the interconnect performance, as well as input matrix characteristics such as such as the number and location of nonzeros. We present LUsim, a simulation framework for modeling the performance of sparse LU factorization. Our framework uses micro-benchmarks to calibrate the param… more
Date: April 15, 2008
Creator: Univ. of California, San Diego
Partner: UNT Libraries Government Documents Department
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Gravity monitoring of CO2 movement during sequestration: Model studies

Description: We examine the relative merits of gravity measurements as a monitoring tool for geological CO{sub 2} sequestration in three different modeling scenarios. The first is a combined CO{sub 2} enhanced oil recovery (EOR) and sequestration in a producing oil field, the second is sequestration in a brine formation, and the third is for a coalbed methane formation. EOR/sequestration petroleum reservoirs have relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine… more
Date: July 15, 2008
Creator: Gasperikova, E. & Hoversten, G.M.
Partner: UNT Libraries Government Documents Department
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