Addressing Failures in Exascale Computing (open access)

Addressing Failures in Exascale Computing

This report talks about the Exascale Computing Failures in detail.
Date: April 24, 2013
Creator: Snir, M.; Wisniewski, R. W.; Abraham, J. A.; Adve, S. V.; Bagchi, S.; Balaji, P. et al.
Object Type: Report
System: The UNT Digital Library
Compositional threshold for Nuclear Waste Glass Durability (open access)

Compositional threshold for Nuclear Waste Glass Durability

Within the composition space of glasses, a distinct threshold appears to exist that separates "good" glasses, i.e., those which are sufficiently durable, from "bad" glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region.
Date: April 24, 2013
Creator: Kruger, Albert A.; Farooqi, Rahmatullah & Hrma, Pavel R.
Object Type: Article
System: The UNT Digital Library
Cosmic Ray Studies with the Fermi Gamma-ray Space Telescope Large Area Telescope (open access)

Cosmic Ray Studies with the Fermi Gamma-ray Space Telescope Large Area Telescope

None
Date: April 24, 2013
Creator: Thompson, D. J.; Baldini, L. & Uchiyama, Y.
Object Type: Article
System: The UNT Digital Library
Flow Shear Effects in the Onset Physics of Resistive MHD Instabilities in Tokamaks. Final report (open access)

Flow Shear Effects in the Onset Physics of Resistive MHD Instabilities in Tokamaks. Final report

The progress in this research centers around the computational analysis of flow shear effects in the onset of a 3/2 mode driven by a 1/1 mode in DIII-D equilibria. The initial idea was to try and calculate, via nonlinear simulations with NIMROD, the effects of rotation shear on driven 3/2 and 2/1 seed island physics, in experimentally relevant DIIID equilibria. The simulations indicated that very small seed islands were directly driven, as shielding between the sawtooth and the surfaces is significant at the high Lundquist numbers of the experiment. Instead, long after the initial crash the difference in linear stability of the 3/2, which remained prevalent despite the flattening of the core profiles from the sawtooth, contributed to a difference in the eventual seed island evolution. Essentially the seed islands grew or decayed long after the sawtooth crash, and not directly from it. Effectively the dominant 1/1 mode was found to be dragging the coupled modes surrounding it at a high rate through the plasma at their surfaces. The 1/1 mode is locked to the local frame of the plasma in the core, where the flow rate is greatest. The resonant perturbations at the surrounding surfaces propagate in the 'high …
Date: April 24, 2013
Creator: Brennan, Dylan P.
Object Type: Report
System: The UNT Digital Library
A Fundamental Investigation on the Structural Dynamics of Model Siloxane Networks under Extreme Pressure (open access)

A Fundamental Investigation on the Structural Dynamics of Model Siloxane Networks under Extreme Pressure

None
Date: April 24, 2013
Creator: Harley, S J & Lewicki, J P
Object Type: Report
System: The UNT Digital Library
Geometrical Optics of Dense Aerosols (open access)

Geometrical Optics of Dense Aerosols

Assembling a free-standing, sharp-edged slab of homogeneous material that is much denser than gas, but much more rare ed than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed fi eld, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the nite particle density reduces the eff ective Stokes number of the flow, a critical result for controlled focusing. __________________________________________________
Date: April 24, 2013
Creator: Hay, Michael J.; Valeo, Ernest J. & Fisch, Nathaniel J.
Object Type: Report
System: The UNT Digital Library
Interactions in 1-ethyl-3-methyl imidazolium tetracyanoborate ion pair: Spectroscopic and density functional study (open access)

Interactions in 1-ethyl-3-methyl imidazolium tetracyanoborate ion pair: Spectroscopic and density functional study

Density Functional Theory is used to investigate a weakly coordinating room-temperature ionic liquid, 1-ethyl-3-methyl imidazolium tetracyanoborate ([Emim]{sup +}[TCB]{sup -}). Four locally stable conformers of the ion pair were located. Atoms-in-molecules (AIM) and electron density analysis indicated the existence of several hydrogen bonds. Further investigation through the Natural Bond Orbital (NBO) and Natural Energy Decomposition Analysis (NEDA) calculations provided insight into the origin of interactions in the [Emim]{sup +}[TCB]{sup -} ion pair. Strength of molecular interactions in the ionic liquid was correlated with frequency shifts of the characteristic vibrations of the ion pair. Harmonic vibrations of the ion pair were also compared with the experimental Raman and Infrared spectra. Vibrational frequencies were assigned by visualizing displacements of atoms around their equilibrium positions and through Potential Energy Distribution (PED) analysis.
Date: April 24, 2013
Creator: Mao, James X.; Lee, Anita S.; Kitchin, John R.; Nulwala, Hunaid B; Luebke, David R. & Damodaran, Krishnan
Object Type: Article
System: The UNT Digital Library
ION EXCHANGE PERFORMANCE OF TITANOSILICATES, GERMANATES AND CARBON NANOTUBES (open access)

ION EXCHANGE PERFORMANCE OF TITANOSILICATES, GERMANATES AND CARBON NANOTUBES

This report presents a summary of testing the affinity of titanosilicates (TSP), germanium-substituted titanosilicates (Ge-TSP) and multiwall carbon nanotubes (MWCNT) for lanthanide ions in dilute nitric acid solution. The K-TSP ion exchanger exhibited the highest affinity for lanthanides in dilute nitric acid solutions. The Ge-TSP ion exchanger shows promise as a material with high affinity, but additional tests are needed to confirm the preliminary results. The MWCNT exhibited much lower affinities than the K-TSP in dilute nitric acid solutions. However, the MWCNT are much more chemically stable to concentrated nitric acid solutions and, therefore, may candidates for ion exchange in more concentrated nitric acid solutions. This technical report serves as the deliverable documenting completion of the FY13 research milestone, M4FT-13SR0303061 – measure actinide and lanthanide distribution values in nitric acid solutions with sodium and potassium titanosilicate materials.
Date: April 24, 2013
Creator: Alsobrook, A. & Hobbs, D.
Object Type: Report
System: The UNT Digital Library
Jet Substructure in ATLAS (open access)

Jet Substructure in ATLAS

None
Date: April 24, 2013
Creator: Miller, David W.
Object Type: Article
System: The UNT Digital Library
LEEM investigations of clean surfaces driven by energetic ion beams (open access)

LEEM investigations of clean surfaces driven by energetic ion beams

The original purpose of this award was to use low‐energy electron microscopy (LEEM) to explore the dynamics of surfaces of clean single crystal surfaces when driven by a beam of energetic ions. The goal was to understand the nanoscience of hyperthermal growth, surface erosion by sublimation and irradiation, operation of surface sinks in irradiated materials, diffusion on driven surfaces, and the creation of structural patterns. This project was based on a novel LEEM system constructed by C. P. Flynn, which provided real‐time imaging of surface dynamics by scattering low energy electrons. With the passing of Prof. Flynn in late 2011, this project was completed under a slightly different scope by constructing a low‐energy, inelastic electron scattering (�EELS�) instrument. Consistent with Flynn�s original objectives for his LEEM system, this device probes the dynamics of crystal surfaces. However the measurements are not carried out in real time, but instead are done in the frequency domain, through the energy lost from the probe electrons. The purpose of this device is to study the collective bosonic excitations in a variety of materials, including high temperature superconductors, topological insulators, carbon allotropes including (but not limited to) graphene, etc. The ultimate goal here is to identify …
Date: April 24, 2013
Creator: Abbamonte, Peter M.
Object Type: Report
System: The UNT Digital Library
Properties of Alfven Eigenmodes in the TAE range on the National Spherical Torus Experiment-Upgrade (open access)

Properties of Alfven Eigenmodes in the TAE range on the National Spherical Torus Experiment-Upgrade

A second Neutral Beam (NB) injection line is being installed on the NSTX Upgrade device, resulting in six NB sources with di erent tangency radii that will be available for heating and current drive. This work explores the properties of instabilities in the frequency range of the Toroidal Alfv#19;en Eigenmode (TAE) for NSTX-U scenarios with various NB injection geometries, from more perpendicular to more tangential, and with increased toroidal magnetic eld with respect to previous NSTX scenarios. Predictions are based on analysis through the ideal MHD code NOVA-K. For the scenarios considered in this work, modi cations of the Alfv#19;en continuum result in a frequency upshift and a broadening of the radial mode structure. The latter e ect may have consequences for fast ion transport and loss. Preliminary stability considerations indicate that TAEs are potentially unstable, with ion Landau damping representing the dominant damping mechanism
Date: April 24, 2013
Creator: unknown
Object Type: Report
System: The UNT Digital Library
redMaPPer I: Algorithm and SDSS DR8 Catalog (open access)

redMaPPer I: Algorithm and SDSS DR8 Catalog

None
Date: April 24, 2013
Creator: Rykoff, E. S.; Rozo, E.; Busha, M. T.; Cunha, C. E.; Finoguenov, A.; Evrard, A. et al.
Object Type: Article
System: The UNT Digital Library
redMaPPer II: X-ray and SZ Performance Benchmarks for the SDSS Catalog (open access)

redMaPPer II: X-ray and SZ Performance Benchmarks for the SDSS Catalog

None
Date: April 24, 2013
Creator: Rozo, Eduardo & Rykoff, Eli S.
Object Type: Article
System: The UNT Digital Library
Betatron-Function Measurement in Lattices with 90-Degrees Sections (open access)

Betatron-Function Measurement in Lattices with 90-Degrees Sections

Lattice functions derived from betatron phase-advance measurements have been used successfully at many e{sup +}-e{sup -} facilities in the world, including at the PEP-II High Energy Ring. For the Low energy Ring of PEP-II, however, extraction of meaningful beta functions is hampered by the 90{sup o} phase advance/cell in the arcs, which causes a singularity in the expressions for beta. An algorithm has been developed calculating beta functions based on {beta} and {alpha} at the beginning of an arc and tracking the Twiss parameters through the arc while matching the observed phase advance/cell. Stability of the algorithm is improved by doing the same calculation 'backward' as well as forward and averaging the result. The algorithm allows estimating beta functions at bad BPMs in many cases. The paper presents the algorithm used as well as examples of use in PEP.
Date: April 24, 2012
Creator: Wienands, U. & Biagini, M.E.
Object Type: Report
System: The UNT Digital Library
Dielectric-Lined High-Gradient Accelerator Structure (open access)

Dielectric-Lined High-Gradient Accelerator Structure

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 …
Date: April 24, 2012
Creator: Hirshfield, Jay L.
Object Type: Report
System: The UNT Digital Library
FINAL TECHNICAL REPORT FOR FORESTRY BIOFUEL STATEWIDE COLLABORATION CENTER (MICHIGAN) (open access)

FINAL TECHNICAL REPORT FOR FORESTRY BIOFUEL STATEWIDE COLLABORATION CENTER (MICHIGAN)

A team composed of scientists from Michigan State University (MSU) and Michigan Technological University (MTU) assembled to better understand, document, and improve systems for using forest-based biomass feedstocks in the production of energy products within Michigan. Work was funded by a grant (DE-EE-0000280) from the U.S. Department of Energy (DOE) and was administered by the Michigan Economic Development Corporation (MEDC). The goal of the project was to improve the forest feedstock supply infrastructure to sustainably provide woody biomass for biofuel production in Michigan over the long-term. Work was divided into four broad areas with associated objectives: • TASK A: Develop a Forest-Based Biomass Assessment for Michigan – Define forest-based feedstock inventory, availability, and the potential of forest-based feedstock to support state and federal renewable energy goals while maintaining current uses. • TASK B: Improve Harvesting, Processing and Transportation Systems – Identify and develop cost, energy, and carbon efficient harvesting, processing and transportation systems. • TASK C: Improve Forest Feedstock Productivity and Sustainability – Identify and develop sustainable feedstock production systems through the establishment and monitoring of a statewide network of field trials in forests and energy plantations. • TASK D: Engage Stakeholders – Increase understanding of forest biomass production systems …
Date: April 24, 2012
Creator: LaCourt, Donna M.; Miller, Raymond O. & Shonnard, David R.
Object Type: Report
System: The UNT Digital Library
High Multiplicity Searches at the LHC Using Jet Masses (open access)

High Multiplicity Searches at the LHC Using Jet Masses

This article introduces a new class of searches for physics beyond the Standard Model that improves the sensitivity to signals with high jet multiplicity. The proposed searches gain access to high multiplicity signals by reclustering events into large-radius, or 'fat', jets and by requiring that each event has multiple massive jets. This technique is applied to supersymmetric scenarios in which gluinos are pair-produced and then subsequently decay to final states with either moderate quantities of missing energy or final states without missing energy. In each of these scenarios, the use of jet mass improves the estimated reach in gluino mass by 20% to 50% over current LHC searches.
Date: April 24, 2012
Creator: Hook, Anson; /SLAC /Stanford U., Appl. Phys. Dept.; Izaguirre, Eder; /SLAC /Stanford U., Phys. Dept.; Lisanti, Mariangela; U., /Princeton et al.
Object Type: Article
System: The UNT Digital Library
Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence (open access)

Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence

An existing linear magnetized plasma device, the Controlled Shear Decorrelation experiment (CSDX) was used to study the transition from a state of coherent wave like activity to a state of turbulent activity using the magnetic field and thus magnetization of the plasma as the control parameter. The results show the onset of coherent drift waves consistent with linear stability analysis. As the magnetization is raised, at first multiple harmonics appear, consistent with wave steepening. This period is then followed by the beginning of nonlinear interactions between different wave modes, which then results in the formation of narrow frequency but distributed azimuthal wave number fluctuations that are consistent with the formation of long-lived coherent nonlinear structures within the plasmas. These structures, termed quasicoherent modes, persist as the magnetic field is raised. Measurements of turbulent momentum flux indicate that the plasma is also forming an azimuthally symmetric radially sheared fluid flow that is nonlinearly driven by smaller scaled turbulent fluctuations. Further increases in the magnetic field result in the breakup of the quasicoherent mode, and the clear formation of the sheared flow. Numerical simulations of the experiment reproduce the formation of the sheared flow via a vortex merging process, and confirm that …
Date: April 24, 2012
Creator: Tynan, George R.
Object Type: Report
System: The UNT Digital Library
PEP-II Status and Outlook (open access)

PEP-II Status and Outlook

PEP-II/BABAR are presently in their second physics run. With machine and detector performance and reliability at an all-time high, almost 51 fb{sup -1} have been integrated by BABAR up to mid-October 2001. PEP-II luminosity has reached 4.4 x 10{sup 33} cm{sup -2} s{sup -1} and our highest monthly delivered luminosity has been above 6 pb{sup -1}, exceeding the performance parameters given in the PEP-II CDR by almost 50%. The increase compared to the first run in 2000 has been achieved by a combination of beam-current increase and beam-size decrease. In this paper we will summarize the PEP-II performance and the present limitations as well as our plans to further increase machine performance.
Date: April 24, 2012
Creator: Wienands, H. U.; Biagini, M. E.; Decker, F. J.; Donald, M. H.; Ecklund, S.; Fisher, A. et al.
Object Type: Article
System: The UNT Digital Library
Resolving Lifshitz Horizons (open access)

Resolving Lifshitz Horizons

Via the AdS/CFT correspondence, ground states of field theories at finite charge density are mapped to extremal black brane solutions. Studies of simple gravity + matter systems in this context have uncovered wide new classes of extremal geometries. The Lifshitz metrics characterizing field theories with non-trivial dynamical critical exponent z {ne} 1 emerge as one common endpoint in doped holographic toy models. However, the Lifshitz horizon exhibits mildly singular behaviour - while curvature invariants are finite, there are diverging tidal forces. Here we show that in some of the simplest contexts where Lifshitz metrics emerge, Einstein-Maxwell-dilaton theories, generic corrections lead to a replacement of the Lifshitz metric, in the deep infrared, by a re-emergent AdS{sub 2} x R{sup 2} geometry. Thus, at least in these cases, the Lifshitz scaling characterizes the physics over a wide range of energy scales, but the mild singularity is cured by quantum or stringy effects.
Date: April 24, 2012
Creator: Harrison, Sarah; Kachru, Shamit; Wang, Huajia & /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
Object Type: Report
System: The UNT Digital Library
SAMPLE RESULTS FROM THE INTEGRATED SALT DISPOSITION PROGRAM MACROBATCH 5 TANK 21H QUALIFICATION MST, ESS AND PODD SAMPLES (open access)

SAMPLE RESULTS FROM THE INTEGRATED SALT DISPOSITION PROGRAM MACROBATCH 5 TANK 21H QUALIFICATION MST, ESS AND PODD SAMPLES

Savannah River National Laboratory (SRNL) performed experiments on qualification material for use in the Integrated Salt Disposition Program (ISDP) Batch 5 processing. This qualification material was a composite created from recent samples from Tank 21H and archived samples from Tank 49H to match the projected blend from these two tanks. Additionally, samples of the composite were used in the Actinide Removal Process (ARP) and extraction-scrub-strip (ESS) tests. ARP and ESS test results met expectations. A sample from Tank 21H was also analyzed for the Performance Objectives Demonstration Document (PODD) requirements. SRNL was able to meet all of the requirements, including the desired detection limits for all the PODD analytes. This report details the results of the Actinide Removal Process (ARP), Extraction-Scrub-Strip (ESS) and Performance Objectives Demonstration Document (PODD) samples of Macrobatch (Salt Batch) 5 of the Integrated Salt Disposition Program (ISDP).
Date: April 24, 2012
Creator: Peters, T. & Fink, S.
Object Type: Report
System: The UNT Digital Library
Stress Testing of the Philips 60W Replacement Lamp L Prize Entry (open access)

Stress Testing of the Philips 60W Replacement Lamp L Prize Entry

The Pacific Northwest National Laboratory, operated by Battelle for the U.S. Department of Energy, worked with Intertek to develop a procedure for stress testing medium screw-base light sources. This procedure, composed of alternating stress cycles and performance evaluation, was used to qualitatively compare and contrast the durability and reliability of the Philips 60W replacement lamp L Prize entry with market-proven compact fluorescent lamps (CFLs) with comparable light output and functionality. The stress cycles applied simultaneous combinations of electrical, thermal, vibration, and humidity stresses of increasing magnitude. Performance evaluations measured relative illuminance, x chromaticity and y chromaticity shifts after each stress cycle. The Philips L Prize entry lamps appear to be appreciably more durable than the incumbent energy-efficient technology, as represented by the evaluated CFLs, and with respect to the applied stresses. Through the course of testing, all 15 CFL samples permanently ceased to function as a result of the applied stresses, while only 1 Philips L Prize entry lamp exhibited a failure, the nature of which was minor, non-destructive, and a consequence of a known (and resolved) subcontractor issue. Given that current CFL technology appears to be moderately mature and no Philips L Prize entry failures could be produced within …
Date: April 24, 2012
Creator: Poplawski, Michael E.; Ledbetter, Marc R. & Smith, Mark
Object Type: Report
System: The UNT Digital Library
Technical bases and guidance for the use of composite soil sampling for demonstrating compliance with radiological release criteria (open access)

Technical bases and guidance for the use of composite soil sampling for demonstrating compliance with radiological release criteria

This guidance provides information on methodologies and the technical bases that licensees should consider for incorporating composite sampling strategies into final status survey (FSS) plans. In addition, this guidance also includes appropriate uses of composite sampling for generating the data for other decommissioning site investigations such as characterization or other preliminary site investigations.
Date: April 24, 2012
Creator: Vitkus, Timothy J.
Object Type: Report
System: The UNT Digital Library
Real space soft x-ray imaging at 10 nm spatial resolution (open access)

Real space soft x-ray imaging at 10 nm spatial resolution

Using Fresnel zone plates made with our robust nanofabrication processes, we have successfully achieved 10 nm spatial resolution with soft x-ray microscopy. The result, obtained with both a conventional full-field and scanning soft x-ray microscope, marks a significant step forward in extending the microscopy to truly nanoscale studies.
Date: April 24, 2011
Creator: Chao, Weilun; Fischer, Peter; Tyliszczak, T.; Rekawa, Senajith; Anderson, Erik & Naulleau, Patrick
Object Type: Article
System: The UNT Digital Library