Effect of Ethanol and Methyl-tert-Butyl Ether on Monoaromatic Hydrocarbon Biodegradation: Response Variability for Different Aquifer Materials Under Various Electron-Accepting Conditions (open access)

Effect of Ethanol and Methyl-tert-Butyl Ether on Monoaromatic Hydrocarbon Biodegradation: Response Variability for Different Aquifer Materials Under Various Electron-Accepting Conditions

Aquifer microcosms were used to determine how ethanol and methyl-tert-butyl ether (MtBE) affect monoaromatic hydrocarbon degradation under different electron-accepting conditions commonly found in contaminated sites experiencing natural attenuation. Response variability was investigated by using aquifer material from four sites with different exposure history. The lag phase prior to BTEX (benzene, toluene, ethylbenzene, and xylenes) and ethanol degradation was typically shorter in microcosms with previously contaminated aquifer material, although previous exposure did not always result in high degradation activity. Toluene was degraded in all aquifer materials and generally under a broader range of electron-accepting conditions compared to benzene, which was degraded only under aerobic conditions. MtBE was not degraded within 100 days under any condition, and it did not affect BTEX or ethanol degradation patterns. Ethanol was often degraded before BTEX compounds, and had a variable effect on BTEX degradation as a function of electron-accepting conditions and aquifer material source. An occasional enhancement of toluene degradation by ethanol occurred in denitrifying microcosms with unlimited nitrate; this may be attributable to the fortuitous growth of toluene-degrading bacteria during ethanol degradation. Nevertheless, experiments with flow-through aquifer columns showed that this beneficial effect could be eclipsed by an ethanol-driven depletion of electron acceptors, which …
Date: October 6, 2003
Creator: Ruiz-Aguilar, G L; Fernandez-Sanchez, J M; Kane, S R; Kim, D & Alvarez, P J
Object Type: Article
System: The UNT Digital Library
Analyses in Support of Z-IFE: LLNL Progress Report for FY-04 (open access)

Analyses in Support of Z-IFE: LLNL Progress Report for FY-04

During the last quarter of FY2004, Lawrence Livermore National Laboratory (LLNL) conducted a brief study of power plant options for a z-pinch-based inertial fusion energy (Z-IFE) power plant. Areas that were covered include chamber design, thick-liquid response, neutronics and activation, and systems studies. This report summarizes the progress made in each of these areas, provides recommendations for improvements to the basic design concept, and identifies future work that is needed. As a starting point to the LLNL studies, we have taken information provided in several publications and presentations. In particular, many of the basic parameters were taken from the ZP-3 study, which is described in reference 4. The ZP-3 design called for 12 separate target chambers, with any 10 of them operating at a given time. Each chamber would be pulsed at a repetition rate of 0.1 Hz with a target yield of 3 GJ. Thus, each chamber would have a fusion power of 300 MW for a power plant total of 3000 MW. The ZP-3 study considered several options for the recyclable transmission lines (RTL). Early in the study, the LLNL group questioned the use of many chambers as well as the yield limitation of 3 GJ. The feeling …
Date: October 6, 2004
Creator: Meier, W; Abbott, R; Latkowski, J; Moir, R; Reyes, S & Schmitt, R
Object Type: Report
System: The UNT Digital Library
Investigating Sources of Toxicity in Stormwater: Algae Mortality in Runoff Upstream of the Lawrence Livermore National Laboratory (open access)

Investigating Sources of Toxicity in Stormwater: Algae Mortality in Runoff Upstream of the Lawrence Livermore National Laboratory

A source evaluation case study is presented for observations of algae toxicity in an intermittent stream passing through the Lawrence Livermore National Laboratory near Livermore, California. A five-step procedure is discussed to determine the cause of water toxicity problems and to determine appropriate environmental management practices. Using this approach, an upstream electrical transfer station was identified as the probable source of herbicides causing the toxicity. In addition, an analytical solution for solute transport in overland flow was used to estimate the application level of 40 Kg/ha. Finally, this source investigation demonstrates that pesticides can impact stream water quality regardless of application within levels suggested on manufacturer labels. Environmental managers need to ensure that pesticides that could harm aquatic organisms (including algae) not be used within close proximity to streams or storm drainages and that application timing should be considered for environmental protection.
Date: October 6, 2003
Creator: Campbell, C G; Folks, K; Mathews, S & Martinelli, R
Object Type: Article
System: The UNT Digital Library
Weighted Essentially Non-Oscillatory Simulations and Modeling of Complex Hydrodynamic Flows. Part 2. Single-Mode Richtmyer-Meshkov Instability with Reshock (open access)

Weighted Essentially Non-Oscillatory Simulations and Modeling of Complex Hydrodynamic Flows. Part 2. Single-Mode Richtmyer-Meshkov Instability with Reshock

The Richtmyer-Meshkov instability is a fundamental fluid instability that occurs when perturbations on an interface separating gases with different properties grow following the passage of a shock. This instability is typically studied in shock tube experiments, and constitutes a fundamental example of a complex hydrodynamic flow. Numerical simulations and models for the instability growth and evolution have also been used to further understand the physics of the Richtmyer-Meshkov instability. In the present work, the formally high-order accurate weighted essentially non-oscillatory (WENO) shock-capturing method using a third-order total-variation diminishing (TVD) Runge-Kutta time-evolution scheme (as implemented in the HOPE code [57]) is applied to simulate the single-mode Richtmyer-Meshkov instability with reshock in two spatial dimensions. The initial conditions and computational domain for the simulations are modeled after the Collins and Jacobs [23] single-mode, Mach 1.21 air(acetone)/SF6 shock tube experiment. The following boundary conditions are used: (1) periodic in the spanwise direction corresponding to the cross-section of the test section; (2) outflow at the entrance of the test section in the streamwise direction, and; (3) reflecting at the end wall of the test section in the streamwise direction. The present investigation has three principal motivations: (1) to provide additional validation of the HOPE …
Date: October 6, 2004
Creator: Schilling, O & Latini, M
Object Type: Report
System: The UNT Digital Library
Dataflow and remapping for wavelet compression and realtime view-dependent optimization of billion-triangle isosurfaces (open access)

Dataflow and remapping for wavelet compression and realtime view-dependent optimization of billion-triangle isosurfaces

Currently, large physics simulations produce 3D fields whose individual surfaces, after conventional extraction processes, contain upwards of hundreds of millions of triangles. Detailed interactive viewing of these surfaces requires powerful compression to minimize storage, and fast view-dependent optimization of display triangulations to drive high-performance graphics hardware. In this work we provide an overview of an end-to-end multiresolution dataflow strategy whose goal is to increase efficiencies in practice by several orders of magnitude. Given recent advancements in subdivision-surface wavelet compression and view-dependent optimization, we present algorithms here that provide the ''glue'' that makes this strategy hold together. Shrink-wrapping converts highly detailed unstructured surfaces of arbitrary topology to the semi-structured form needed for wavelet compression. Remapping to triangle bintrees minimizes disturbing ''pops'' during real-time display-triangulation optimization and provides effective selective-transmission compression for out-of-core and remote access to these huge surfaces.
Date: October 6, 2000
Creator: Duchaineau, M A; Porumbescu, S D; Bertram, M; Hamann, B & Joy, K I
Object Type: Article
System: The UNT Digital Library
Trip Report United Arab Emirates (open access)

Trip Report United Arab Emirates

Keith Nakanishi and Arthur Rodgers traveled to the United Arab Emirates in February, 2004 to continue an on-going technical collaboration with UAE University and to service the two temporary LLNL seismic stations. Nakanishi and Rodgers then participated in the Gulf Seismic Forum, which was organized by LLNL and sponsored by the University of Sharjah.
Date: October 6, 2004
Creator: Nakanishi, K. & Rodgers, A.
Object Type: Report
System: The UNT Digital Library
Bilirubin UDP-Glucuronosyltransferase 1A1 (UGT1A1) Gene Promoter Polymorphisms and HPRT, Glycophorin A, and Micronuclei Mutant Frequencies in Human Blood (open access)

Bilirubin UDP-Glucuronosyltransferase 1A1 (UGT1A1) Gene Promoter Polymorphisms and HPRT, Glycophorin A, and Micronuclei Mutant Frequencies in Human Blood

A dinucleotide repeat polymorphism (5-, 6-, 7-, or 8-TA units) has been identified within the promoter region of UDP-glucuronosyltransferase 1A1 gene (UGT1A1). The 7-TA repeat allele has been associated with elevated serum bilirubin levels that cause a mild hyperbilirubinemia (Gilbert's syndrome). Studies suggest that promoter transcriptional activity of UGT1A1 is inversely related to the number of TA repeats and that unconjugated bilirubin concentration increases directly with the number of TA repeat elements. Because bilirubin is a known antioxidant, we hypothesized that UGT1A1 repeats associated with higher bilirubin may be protective against oxidative damage. We examined the effect of UGT1A1 genotype on somatic mutant frequency in the hypoxanthine-guanine phosphoribosyl-transferase (HPRT) gene in human lymphocytes and the glycophorin A (GPA) gene of red blood cells (both N0, NN mutants), and the frequency of lymphocyte micronuclei (both kinetochore (K) positive or micronuclei K negative) in 101 healthy smoking and nonsmoking individuals. As hypothesized, genotypes containing 7-TA and 8-TA displayed marginally lower GPA{_}NN mutant frequency relative to 5/5, 5/6, 6/6 genotypes (p<0.05). In contrast, our analysis showed that lower expressing UGT1A1 alleles (7-TA and 8-TA) were associated with modestly increased HPRT mutation frequency (p<0.05) while the same low expression genotypes were not significantly associated …
Date: October 6, 2004
Creator: Grant, D.; Hall, I. J.; Eastmond, D.; Jones, I. M. & Bell, D. A.
Object Type: Article
System: The UNT Digital Library
Needs Differing: Personality Dynamics for Peer Ombuds in a Research Setting (open access)

Needs Differing: Personality Dynamics for Peer Ombuds in a Research Setting

The peer ombuds program at University of California's Lawrence Livermore National Laboratory (LLNL) is unique in many respects, and the challenges it poses for its practitioners are likewise unique. The ombuds themselves are members of the workforce they serve, and must constantly fulfill a dual role. Cases range from conflict with supervisors or co-workers to medical leave issues. Mismatched expectations and poor communication skills obviously underlie many problems. The interplay of personality type affects conflict (and its resolution) more subtly, principally through its role in shaping client needs. Through a hypothetical case description, the author highlights the dynamics of personality type involved in the ombuds process at LLNL. The implications of temperamental difference argue for an awareness of, and sensitivity to, type differences in the population served.
Date: October 6, 2004
Creator: Wolford, J. K., Jr.
Object Type: Article
System: The UNT Digital Library
DO -- antiMixing and Rare Charm Decays (open access)

DO -- antiMixing and Rare Charm Decays

We review the current status of flavor-changing neutral currents in the charm sector. We focus on the standard-model predictions and identify the main sources of theoretical uncertainties in both charm mixing and rare charm decays. The potential of these observables for constraining short-distance physics in the standard model and its extensions is compromised by the presence of large nonperturbative effects. We examine the possible discovery windows in which short-distance physics can be tested and study the effects of various extensions of the standard model. The current experimental situation and future prospects are reviewed.
Date: October 6, 2003
Creator: Miller, Jeanne M & Burdman, Gustavo
Object Type: Article
System: The UNT Digital Library
A Laser Technology Test Facility for Laser Inertial Fusion Energy (LIFE) (open access)

A Laser Technology Test Facility for Laser Inertial Fusion Energy (LIFE)

A LIFE laser driver needs to be designed and operated which meets the rigorous requirements of the NIF laser system while operating at high average power, and operate for a lifetime of >30 years. Ignition on NIF will serve to demonstrate laser driver functionality, operation of the Mercury laser system at LLNL demonstrates the ability of a diode-pumped solid-state laser to run at high average power, but the operational lifetime >30 yrs remains to be proven. A Laser Technology test Facility (LTF) has been designed to specifically address this issue. The LTF is a 100-Hz diode-pumped solid-state laser system intended for accelerated testing of the diodes, gain media, optics, frequency converters and final optics, providing system statistics for billion shot class tests. These statistics will be utilized for material and technology development as well as economic and reliability models for LIFE laser drivers.
Date: October 6, 2009
Creator: Bayramian, A. J.; Campbell, R. W.; Ebbers, C. A.; Freitas, B. L.; Latkowski, J.; Molander, W. A. et al.
Object Type: Article
System: The UNT Digital Library
QCD Corrections in Transversely Polarized Scattering (open access)

QCD Corrections in Transversely Polarized Scattering

We discuss two recent calculations of higher-order QeD corrections to scattering of transversely polarized hadrons. A basic concept underlying much of the theoretical description of high-energy hadronic scattering is the factorization theorem, which states that large momentum-transfer reactions may be factorized into long-distance pieces that contain information on the structure of the nucleon in terms of its parton densities, and parts that are short-distance and describe the hard interactions of the partons. Two crucial points are that on the one hand the long-distance contributions are universal, i.e., they are the same in any inelastic reaction under consideration, and that on the other hand the short-distance pieces depend only on the large scales related to the large momentum transfer in the overall reaction and, therefore, may be evaluated using QCD perturbation theory. The lowest order for the latter can generally only serve to give a rough description of the reaction under study. It merely captures the main features, but does not usually provide a quantitative understanding. The first-order ('next-to-leading order' (NLO)) corrections are generally indispensable in order to arrive at a firmer theoretical prediction for hadronic cross sections, and in some cases even an all-order resummation of large perturbative corrections is …
Date: October 6, 2008
Creator: Vogelsang, W.
Object Type: Article
System: The UNT Digital Library
Enhancing Condensers for Geothermal Systems: the Effect of High Contact Angles on Dropwise Condensation Heat Transfer (open access)

Enhancing Condensers for Geothermal Systems: the Effect of High Contact Angles on Dropwise Condensation Heat Transfer

Phase change heat transfer is notorious for increasing the irreversibility of, and therefore decreasing the efficiency of, geothermal power plants. Its significant contribution to the overall irreversibility of the plant makes it the most important source of inefficiency in the process. Recent studies here have shown the promotion of drop wise condensation in the lab by means of increasing the surface energy density of a tube with nanotechnology. The use of nanotechnology has allowed the creation of surface treatments which discourage water from wetting a tube surface during a static test. These surface treatments are unique in that they create high- contact angles on the condensing tube surfaces to promote drop wise condensation.
Date: October 6, 2009
Creator: Kennedy, John M.; Kim, Sunwoo & Kim, Kwang J.
Object Type: Text
System: The UNT Digital Library
RHIC Polarized proton performance in run-8 (open access)

RHIC Polarized proton performance in run-8

During Run-8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin-polarized proton beams at two interaction regions. Physics data were taken with vertical orientation of the beam polarization, which in the 'Yellow' RHIC ring was significantly lower than in previous years. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run-8, and we discuss possible causes of the not as high as previously achieved polarization performance of the 'Yellow' ring.
Date: October 6, 2008
Creator: Montag, C.; Bai, M.; MacKay, W. W.; Roser, T.; Abreu, N.; Ahrens, L. et al.
Object Type: Article
System: The UNT Digital Library
The Future of High Energy Polarized Proton Beams (open access)

The Future of High Energy Polarized Proton Beams

None
Date: October 6, 2008
Creator: Roser, T.
Object Type: Article
System: The UNT Digital Library
Selection and Implementation of a Replacement Cutting Tool Selection Application (open access)

Selection and Implementation of a Replacement Cutting Tool Selection Application

A new commercial cutting tool software package replaced an internally created legacy system. This report describes the issues that surfaced during the migration and installation of the commercial package and the solutions employed. The primary issues discussed are restructuring the data between two drastically different database schemas and the creation of individual component graphics.
Date: October 6, 2008
Creator: Rice, Gordon
Object Type: Report
System: The UNT Digital Library
Spin resonance strength calculations (open access)

Spin resonance strength calculations

In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.
Date: October 6, 2008
Creator: Courant, E. D.
Object Type: Article
System: The UNT Digital Library
Addendum to Engineering Evaluation of Proposed Alternative Salt Transfer Method for the Molten Salt Reactor Experiement for the Oak Ridge National Laboratory (open access)

Addendum to Engineering Evaluation of Proposed Alternative Salt Transfer Method for the Molten Salt Reactor Experiement for the Oak Ridge National Laboratory

The purpose of this addendum is to graphically publish data which indicate moisture in leakage and corrosion may have occurred during heating of the tanks at the Molten Salt Reactor Experiment (MSRE) for and during hydrofluorination, fluorination and transfer of uranium. Corrosion, especially by hydrofluoric acid, is not expected to occur uniformly over the tank and piping inner surfaces and therefore is not easily measured by nondestructive techniques that can measure only limited areas. The rate of corrosion exponentially escalates with both temperature and moisture. The temperature, pressure, and concentration data in this addendum indicate periods when elevated corrosion rates were likely to have been experienced. This data was not available in time to be considered as part of the evaluation that was the focus of the report. Pressure and temperature data were acquired via the LabView{trademark} Software, while concentration data was acquired from the Fourier Transform InfraRed (FTIR) system.
Date: October 6, 2009
Creator: Wilson, Guy
Object Type: Report
System: The UNT Digital Library
RESULTS FOR THE FIRST QUARTER 2009 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS (open access)

RESULTS FOR THE FIRST QUARTER 2009 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS

This report details the chemical and radionuclide contaminant results for the characterization of the 2009 First Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC). Information from this characterization will be used by Liquid Waste Operations (LWO) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: (1) The concentrations of the chemical and radioactive contaminants were all less than their respective WAC Targets or Limits except for Am-242m. (2) The radionuclide Am-242m was not detected; however, its detection limit is above the WAC Target given in Attachment 8.4. The higher detection limit was expected based on current analytical capabilities as stated in the Task Technical and Quality Assurance Plan (TTQAP). (3) The reported detection limit of isopropanol was lower than its WAC Limit for accident analysis but higher than its WAC concentration given in Table 4 for vault flammability. The higher detection limit was expected based on current analytical capabilities and is …
Date: October 6, 2009
Creator: Reigel, M.; Diprete, C. & Bibler, N.
Object Type: Report
System: The UNT Digital Library
Predicting Efficient Antenna Ligands for Tb(III) Emission (open access)

Predicting Efficient Antenna Ligands for Tb(III) Emission

A series of highly luminescent Tb(III) complexes of para-substituted 2-hydroxyisophthalamide ligands (5LI-IAM-X) has been prepared (X = H, CH{sub 3}, (C=O)NHCH{sub 3}, SO{sub 3}{sup -}, NO{sub 2}, OCH{sub 3}, F, Cl, Br) to probe the effect of substituting the isophthalamide ring on ligand and Tb(III) emission in order to establish a method for predicting the effects of chromophore modification on Tb(III) luminescence. The energies of the ligand singlet and triplet excited states are found to increase linearly with the {pi}-withdrawing ability of the substituent. The experimental results are supported by time-dependent density functional theory (TD-DFT) calculations performed on model systems, which predict ligand singlet and triplet energies within {approx}5% of the experimental values. The quantum yield ({Phi}) values of the Tb(III) complex increases with the triplet energy of the ligand, which is in part due to the decreased non-radiative deactivation caused by thermal repopulation of the triplet. Together, the experimental and theoretical results serve as a predictive tool that can be used to guide the synthesis of ligands used to sensitize lanthanide luminescence.
Date: October 6, 2008
Creator: Samuel, Amanda P.S.; Xu, Jide & Raymond, Kenneth
Object Type: Article
System: The UNT Digital Library
Photoproduction at RHIC and the LHC (open access)

Photoproduction at RHIC and the LHC

The strong electromagnetic fields carried by relativistic highly charged ions make heavy-ion colliders attractive places to study photonuclear interactions and two-photon interactions. At RHIC, three experiments have studied coherent photoproduction of {rho}{sup 0}, 4{pi}, J/{psi}, e{sup +}e{sup -} pairs, and e{sup +}e{sup -} pairs where the electron is bound to one of the incident nuclei. These results show that photoproduction studies are possible, and demonstrate some of the unique possibilities due to the symmetric final states and the ion targets. The LHC will reach photon-nucleon energies many times higher than at HERA; these collisions can be used to measure the gluon distributions in nuclei at very low Bjorken-x, where shadowing and gluon saturation may become important; LHC {gamma}{gamma} collisions may also be attractive places to search for some types of new physics. ATLAS, CMS and ALICE are all planning to study photoproduction. After introducing the principles of photoproduction at hadron colliders, I will review recent results from RHIC on meson and e{sup +}e{sup -} production, and then discuss prospects for studies at the LHC.
Date: October 6, 2008
Creator: Klein, Spencer
Object Type: Article
System: The UNT Digital Library
Tough, bio-inspired hybrid materials (open access)

Tough, bio-inspired hybrid materials

The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs extremely difficult to replicate synthetically. Here we emulate Nature's toughening mechanisms through the combination of two ordinary compounds, aluminum oxide and polymethylmethacrylate, into ice-templated structures whose toughness can be over 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic material whose high yield strength and fracture toughness ({approx}200 MPa and {approx}30 MPa{radical}m) provide specific properties comparable to aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.
Date: October 6, 2008
Creator: Munch, Etienne; Launey, Maximimilan E.; Alsem, Daan H.; Saiz, Eduardo; Tomsia, Antoni P. & Ritchie, Robert O.
Object Type: Article
System: The UNT Digital Library
Class-specific Error Bounds for Ensemble Classifiers (open access)

Class-specific Error Bounds for Ensemble Classifiers

The generalization error, or probability of misclassification, of ensemble classifiers has been shown to be bounded above by a function of the mean correlation between the constituent (i.e., base) classifiers and their average strength. This bound suggests that increasing the strength and/or decreasing the correlation of an ensemble's base classifiers may yield improved performance under the assumption of equal error costs. However, this and other existing bounds do not directly address application spaces in which error costs are inherently unequal. For applications involving binary classification, Receiver Operating Characteristic (ROC) curves, performance curves that explicitly trade off false alarms and missed detections, are often utilized to support decision making. To address performance optimization in this context, we have developed a lower bound for the entire ROC curve that can be expressed in terms of the class-specific strength and correlation of the base classifiers. We present empirical analyses demonstrating the efficacy of these bounds in predicting relative classifier performance. In addition, we specify performance regions of the ROC curve that are naturally delineated by the class-specific strengths of the base classifiers and show that each of these regions can be associated with a unique set of guidelines for performance optimization of binary …
Date: October 6, 2009
Creator: Prenger, Ryan J.; Lemmond, Tracy D.; Varshney, Kush R.; Chen, Barry Y. & Hanley, William G.
Object Type: Article
System: The UNT Digital Library
Top Jets at the LHC (open access)

Top Jets at the LHC

We investigatethe reconstruction of high pT hadronically-decaying top quarksat the Large Hadron Collider. One of the main challenges in identifying energetictop quarks is that the decay products become increasingly collimated. This reducesthe efficacy of conventional reconstruction methods that exploit the topology of thetop quark decay chain. We focus on the cases where the decay products of the topquark are reconstructed as a single jet, a"top-jet." The most basic"top-tag" methodbased on jet mass measurement is considered in detail. To analyze the feasibility ofthe top-tagging method, both theoretical and experimental aspects of the large QCDjet background contribution are examined. Based on a factorization approach, wederive a simple analytic approximation for the shape of the QCD jet mass spectrum.We observe very good agreement with the Monte Carlo simulation. We consider high pT tt bar production in the Standard Model as an example, and show that our theoretical QCD jet mass distributions can efficiently characterize the background via sideband analyses. We show that with 25 fb-1 of data, our approach allows us to resolve top-jets with pT _> 1 TeV, from the QCD background, and about 1.5 TeV top-jets with 100 fb-1, without relying on b-tagging. To further improve the significancewe consider jet shapes …
Date: October 6, 2008
Creator: Almeida, L.G.; Lee, S.J.; Perez, G.; Sung, I. & Virzi, J.
Object Type: Article
System: The UNT Digital Library
The Vetter-Sturtevant Shock Tube Problem in KULL (open access)

The Vetter-Sturtevant Shock Tube Problem in KULL

The goal of the EZturb mix model in KULL is to predict the turbulent mixing process as it evolves from Rayleigh-Taylor, Richtmyer-Meshkov, or Kelvin-Helmholtz instabilities. In this report we focus on an example of the Richtmyer-Meshkov instability (which occurs when a shock hits an interface between fluids of different densities) with the additional complication of reshock. The experiment by Vetter & Sturtevant (VS) [1], involving a Mach 1.50 incident shock striking an air/SF{sub 6} interface, is a good one to model, now that we understand how the model performs for the Benjamin shock tube [2] and a prototypical incompressible Rayleigh-Taylor problem [3]. The x-t diagram for the VS shock tube is quite complicated, since the transmitted shock hits the far wall at {approx}2 millisec, reshocks the mixing zone slightly after 3 millisec (which sets up a release wave that hits the wall at {approx}4 millisec), and then the interface is hit with this expansion wave around 5 millisec. Needless to say, this problem is much more difficult to model than the Bejamin shock tube.
Date: October 6, 2005
Creator: Ulitsky, M S
Object Type: Report
System: The UNT Digital Library