Light-Front Holographic Quantum Chromodynamics (open access)

Light-Front Holographic Quantum Chromodynamics

None
Date: September 23, 2013
Creator: Brodsky, Stanley J.; de Teramond, Guy F. & Dosch, Hans Gunter
Object Type: Article
System: The UNT Digital Library
A PROTOTYPE FOUR INCH SHORT HYDRIDE (FISH) BED AS A REPLACEMENT TRITIUM STORAGE BED (open access)

A PROTOTYPE FOUR INCH SHORT HYDRIDE (FISH) BED AS A REPLACEMENT TRITIUM STORAGE BED

The Savannah River Site (SRS) tritium facilities have used 1st generation (Gen1) metal hydride storage bed assemblies with process vessels (PVs) fabricated from 3 inch nominal pipe size (NPS) pipe to hold up to 12.6 kg of LaNi{sub 4.25}Al{sub 0.75} metal hydride for tritium gas absorption, storage, and desorption for over 15 years. The 2nd generation (Gen2) of the bed design used the same NPS for the PV, but the added internal components produced a bed nominally 1.2 m long, and presented a significant challenge for heater cartridge replacement in a footprint limited glove-box. A prototype 3rd generation (Gen3) metal hydride storage bed has been designed and fabricated as a replacement candidate for the Gen2 storage bed. The prototype Gen3 bed uses a PV pipe diameter of 4 inch NPS so the bed length can be reduced below 0.7 m to facilitate heater cartridge replacement. For the Gen3 prototype bed, modeling results show increased absorption rates when using hydrides with lower absorption pressures. To improve absorption performance compared to the Gen2 beds, a LaNi{sub 4.15}Al{sub 0.85} material was procured and processed to obtain the desired pressure-composition-temperature (PCT) properties. Other bed design improvements are also presented.
Date: February 23, 2011
Creator: Klein, J.; Estochen, E.; Shanahan, K. & Heung, L.
Object Type: Article
System: The UNT Digital Library
AutomaDeD: Automata-Based Debugging for Dissimilar Parallel Tasks (open access)

AutomaDeD: Automata-Based Debugging for Dissimilar Parallel Tasks

Today's largest systems have over 100,000 cores, with million-core systems expected over the next few years. This growing scale makes debugging the applications that run on them a daunting challenge. Few debugging tools perform well at this scale and most provide an overload of information about the entire job. Developers need tools that quickly direct them to the root cause of the problem. This paper presents AutomaDeD, a tool that identifies which tasks of a large-scale application first manifest a bug at a specific code region at a specific point during program execution. AutomaDeD creates a statistical model of the application's control-flow and timing behavior that organizes tasks into groups and identifies deviations from normal execution, thus significantly reducing debugging effort. In addition to a case study in which AutomaDeD locates a bug that occurred during development of MVAPICH, we evaluate AutomaDeD on a range of bugs injected into the NAS parallel benchmarks. Our results demonstrate that detects the time period when a bug first manifested itself with 90% accuracy for stalls and hangs and 70% accuracy for interference faults. It identifies the subset of processes first affected by the fault with 80% accuracy and 70% accuracy, respectively and the …
Date: March 23, 2010
Creator: Bronevetsky, G; Laguna, I; Bagchi, S; de Supinski, B R; Ahn, D & Schulz, M
Object Type: Article
System: The UNT Digital Library
SECAD-- a Schema-based Environment for Configuring, Analyzing and Documenting Integrated Fusion Simulations. Final report (open access)

SECAD-- a Schema-based Environment for Configuring, Analyzing and Documenting Integrated Fusion Simulations. Final report

SECAD is a project that developed a GUI for running integrated fusion simulations as implemented in FACETS and SWIM SciDAC projects. Using the GUI users can submit simulations locally and remotely and visualize the simulation results.
Date: May 23, 2012
Creator: Shasharina, Svetlana
Object Type: Report
System: The UNT Digital Library
Design and Construction of Prototype Dark Matter Detectors (open access)

Design and Construction of Prototype Dark Matter Detectors

The Lepton Quark Studies (LQS) group is engaged in searching for dark matter using the Dark Matter Time Projection Chamber (DMTPC) at the Waste Isolation Pilot Plant (WIPP) (Carlsbad, NM). DMTPC is a direction-sensitive dark matter detector designed to measure the recoil direction and energy deposited by fluorine nuclei recoiling from the interaction with incident WIMPs. In the past year, the major areas of progress have been: #15; to publish the #12;first dark matter search results from a surface run of the DMTPC prototype detector, #15; to build and install the 10L prototype in the underground laboratory at WIPP which will house the 1 m{sup 3} detector, and #15; to demonstrate charge and PMT readout of the TPC using prototype detectors, which allow triggering and #1;{Delta}z measurement to be used in the 1 m{sup 3} detector under development.
Date: March 23, 2012
Creator: Fisher, Peter
Object Type: Report
System: The UNT Digital Library
Climate change and forests in India: note from the guest editors (open access)

Climate change and forests in India: note from the guest editors

Forestry is one of the most important sectors in the context of climate change. It lies at the center-stage of global mitigation and adaptation efforts. Yet, it is one of the least understood sectors, especially in tropical zones, which constitute a significant portion of the global forests. Recently, there has been a growing interest in forests in addressing global climate change. The IPCC Assessment Report 4 (2007) Chapters related to forests have highlighted the limited number of studies on the impact of climate change on forests at the regional, national and sub-national level, while policy makers need information at these scales. Further, implication of projected climate change on mitigation potential of forest sector is only briefly mentioned in the IPCC report, with limited literature to support the conclusions. India is one among the top ten nations in the world in terms of forest cover. It is also sixth among the tropical countries in terms of forested area. As IPCC Assessment Report 5 work is about to be initiated soon, studies on the impact of climate change on forests as well as the mitigation potential of the forest sector, particularly at regional and national level, will be of great interest to …
Date: December 23, 2010
Creator: Ravindtranath, N.H. & Aaheim, Asbjporn
Object Type: Article
System: The UNT Digital Library
TUNING SILICON NANORODS FOR ANODES OF LI-ION RECHARGEABLE BATTERIES (open access)

TUNING SILICON NANORODS FOR ANODES OF LI-ION RECHARGEABLE BATTERIES

Silicon is a promising anode material for Li-ion batteries in regarding of high capacity, low cost and safety, but it suffers poor cycling stability due to the pulverization induced by severe volume expansion/shrinkage (297%) during lithium insertion/extraction. In our previous investigation on aluminum nanorods anodes, it is found the selection of substrates in which Al nanorods grown plays the role in prevention of pulverization resulting in the increase of cycling life. Adapting this knowledge, we investigated the Si based nanorods anodes by tuning its composition and element distribution. Our results show that although the Si nanorods demonstrated higher initial anodic capacity of 1500 mAh/g, it diminished after 50 cycles due to morphology change and pulverization. By codepositing Cu, the Si-Cu composite nanorods demonstrated sustainable capacity of 500 mAh/g in 100 cycles attributing to its flexible and less brittle nature.
Date: November 23, 2010
Creator: Au, M.
Object Type: Article
System: The UNT Digital Library
A Model for Tow Impregnation and Consolidation for Partially Impregnated Thermoset Prepregs (open access)

A Model for Tow Impregnation and Consolidation for Partially Impregnated Thermoset Prepregs

The formation and transport of voids in composite materials remains a key research area in composite manufacturing science. Knowledge of how voids, resin, and fiber reinforcement propagate throughout a composite material continuum from green state to cured state during an automated tape layup process is key to minimizing defects induced by void-initiated stress concentrations under applied loads for a wide variety of composite applications. This paper focuses on modeling resin flow in a deforming fiber tow during an automated process of partially impregnated thermoset prepreg composite material tapes. In this work, a tow unit cell based model has been presented that determines the consolidation and impregnation of a thermoset prepreg tape under an input pressure profile. A parametric study has been performed to characterize the behavior of varying tow speed and compaction forces on the degree of consolidation. Results indicate that increased tow consolidation is achieved with slower tow speeds and higher compaction forces although the relationship is not linear. The overall modeling of this project is motivated to address optimization of the 'green state' composite properties and processing parameters to reduce or eliminate 'cured state' defects, such as porosity and de-lamination. This work is partially funded by the Department …
Date: May 23, 2011
Creator: Jr, John J. Gangloff; Sinha, Shatil & Advani, Suresh G.
Object Type: Article
System: The UNT Digital Library
Changes to MFRSRCLDOD1MIN Datastream (open access)

Changes to MFRSRCLDOD1MIN Datastream

Significant updates were made to the multifilter rotating shadowband radiometer (MFRSR) cloud optical depth (MFRSRCLDOD) value-added product (VAP) in 2011. The original intent of the update was to add quality control (QC) flags and to update the VAP to use the improved retrievals of liquid water path (LWP) from the Microwave Radiometer Retrievals (MWRRET) VAP rather than the statistical retrievals of LWP from the Microwave Radiometer Line of Sight (MWRLOS) datastream. Although this was originally intended to be a straightforward update of the code, it became more complicated due to the following factors: (1) a new developer and translator team were working with the code; (2) numerous small changes had to be made to the code to consistently implement the QC flags; and (3) ARM standards have changed over the years since the code was originally developed.
Date: May 23, 2012
Creator: McFarlane, S. & Shi, Y.
Object Type: Report
System: The UNT Digital Library
Carboxysomal carbonic anhydrases: Structure and role in microbial CO2 fixation (open access)

Carboxysomal carbonic anhydrases: Structure and role in microbial CO2 fixation

Cyanobacteria and some chemoautotrophic bacteria are able to grow in environments with limiting CO2 concentrations by employing a CO2-concentrating mechanism (CCM) that allows them to accumulate inorganic carbon in their cytoplasm to concentrations several orders of magnitude higher than that on the outside. The final step of this process takes place in polyhedral protein microcompartments known as carboxysomes, which contain the majority of the CO2-fixing enzyme, RubisCO. The efficiency of CO2 fixation by the sequestered RubisCO is enhanced by co-localization with a specialized carbonic anhydrase that catalyzes dehydration of the cytoplasmic bicarbonate and ensures saturation of RubisCO with its substrate, CO2. There are two genetically distinct carboxysome types that differ in their protein composition and in the carbonic anhydrase(s) they employ. Here we review the existing information concerning the genomics, structure and enzymology of these uniquely adapted carbonic anhydrases, which are of fundamental importance in the global carbon cycle.
Date: June 23, 2010
Creator: Cannon, Gordon C.; Heinhorst, Sabine & Kerfeld, Cheryl A.
Object Type: Article
System: The UNT Digital Library
On the Importance of Symmetrizing RF Coupler Fields for Low Emittance Beams (open access)

On the Importance of Symmetrizing RF Coupler Fields for Low Emittance Beams

The input power of accelerator structure is normally fed through a coupling slot(s) on the outer wall of the accelerator structure via magnetic coupling. While providing perfect matching, the coupling slots may produce non-axial-symmetric fields in the coupler cell that can induce emittance growth as the beam is accelerated in such a field. This effect is especially important for low emittance beams at low energies such as in the injector accelerators for light sources. In this paper, we present studies of multipole fields of different rf coupler designs and their effect on beam emittance for an X-band photocathode gun being jointly designed with LLNL, and X-band accelerator structures. We will present symmetrized rf coupler designs for these components to preserve the beam emittance.
Date: June 23, 2011
Creator: Li, Zenghai.; Zhou, Feng.; Vlieks, Arnold. & Adolphsen, Chris.
Object Type: Article
System: The UNT Digital Library
ARPES Studies of Cuprate Fermiology: Superconductivity, Pseudogap and Quasiparticle Dynamics (open access)

ARPES Studies of Cuprate Fermiology: Superconductivity, Pseudogap and Quasiparticle Dynamics

We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below T{sub c}. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a function of temperature and doping, implying that different orders dominate in different momentum-space regions. However, the ubiquity of sharp quasiparticles all around the Fermi surface in Bi-2212 indicates that superconductivity extends into the momentum-space region dominated by the pseudogap, revealing subtlety in this dichotomy. In Bi-2201, the temperature dependence of antinodal spectra reveals particle-hole asymmetry and anomalous spectral broadening, which may constrain the explanation for the pseudogap. Recognizing that electron-boson coupling is an important aspect of cuprate physics, we close with a discussion of the multiple 'kinks' in the nodal dispersion. Understanding these may be important to establishing which excitations are important to superconductivity.
Date: June 23, 2011
Creator: Vishik, Inna
Object Type: Article
System: The UNT Digital Library
STATUS REPORT FOR MOISTURE EFFECTS ON COMPACTION OF FIBERBOARD IN A 9975 SHIPPING PACKAGE (open access)

STATUS REPORT FOR MOISTURE EFFECTS ON COMPACTION OF FIBERBOARD IN A 9975 SHIPPING PACKAGE

Compaction of lower layers in the fiberboard overpack has been observed in 9975 packages that contain elevated moisture. Lab testing has resulted in a better understanding of the relationship between the fiberboard moisture level and compaction of the lower fiberboard assembly, and the behavior of the fiberboard during transport. In laboratory tests, higher moisture content has been shown to correspond to higher total compaction of fiberboard material, greater rate of compaction, and continued compaction over a longer period of time. In addition, laboratory tests have shown that the application of a dynamic load results in higher fiberboard compaction. The test conditions and sample geometric/loading configurations were chosen to simulate the regulatory requirements for 9975 package input dynamic loading. Dynamic testing was conducted over a period of six months to acquire immediate and cumulative changes in geometric data for various moisture levels. Currently, one sample set has undergone a complete dynamic test regimen, while testing of another set is still in-progress. The dynamic input, data acquisition, test effects on sample dynamic parameters, and interim results from this test program are summarized and compared to regulatory specifications for dynamic loading. This will provide a basis from which to evaluate the impact of …
Date: June 23, 2011
Creator: Stefek, T.; Daugherty, W. & Estochen, E.
Object Type: Report
System: The UNT Digital Library
Glass Ceramic Waste Forms for Combined CS+LN+TM Fission Products Waste Streams (open access)

Glass Ceramic Waste Forms for Combined CS+LN+TM Fission Products Waste Streams

In this study, glass ceramics were explored as an alternative waste form for glass, the current baseline, to be used for immobilizing alkaline/alkaline earth + lanthanide (CS+LN) or CS+LN+transition metal (TM) fission-product waste streams generated by a uranium extraction (UREX+) aqueous separations type process. Results from past work on a glass waste form for the combined CS+LN waste streams showed that as waste loading increased, large fractions of crystalline phases precipitated upon slow cooling.[1] The crystalline phases had no noticeable impact on the waste form performance by the 7-day product consistency test (PCT). These results point towards the development of a glass ceramic waste form for treating CS+LN or CS+LN+TM combined waste streams. Three main benefits for exploring glass ceramics are: (1) Glass ceramics offer increased solubility of troublesome components in crystalline phases as compared to glass, leading to increased waste loading; (2) The crystalline network formed in the glass ceramic results in higher heat tolerance than glass; and (3) These glass ceramics are designed to be processed by the same melter technology as the current baseline glass waste form. It will only require adding controlled canister cooling for crystallization into a glass ceramic waste form. Highly annealed waste form …
Date: September 23, 2010
Creator: Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Tang, Ming; Kossoy, Anna & Sickafus, Kurt E.
Object Type: Report
System: The UNT Digital Library
Magnetic stochasticity in gyrokinetic simulations of plasma microturbulence (open access)

Magnetic stochasticity in gyrokinetic simulations of plasma microturbulence

None
Date: November 23, 2010
Creator: Nevins, W M; Wang, E & Candy, J
Object Type: Article
System: The UNT Digital Library
Scoping Thermal Analysis of Alternative Dual-Purpose Canister Disposal Concepts (open access)

Scoping Thermal Analysis of Alternative Dual-Purpose Canister Disposal Concepts

None
Date: June 23, 2013
Creator: Greenberg, H R; Wen, J & Buscheck, T A
Object Type: Report
System: The UNT Digital Library
OECD 2-D Core Concrete Interaction (CCI) tests : CCI-2 test plan, Rev. 0 January 31, 2004. (open access)

OECD 2-D Core Concrete Interaction (CCI) tests : CCI-2 test plan, Rev. 0 January 31, 2004.

The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed …
Date: May 23, 2011
Creator: Farmer, M. T.; Kilsdonk, D. J.; Lomperski, S.; Aeschlimann, R. W. & Basu, S. (Nuclear Engineering Division)
Object Type: Report
System: The UNT Digital Library
Simulation of the High-Pass Filter for 56MHz Cavity for RHIC (open access)

Simulation of the High-Pass Filter for 56MHz Cavity for RHIC

The 56MHz Superconducting RF (SRF) cavity for RHIC places high demands High Order Mode (HOM) damping, as well as requiring a high field at gap with fundamental mode frequency. The damper of 56MHz cavity is designed to extract all modes to the resistance load outside, including the fundamental mode. Therefore, the circuit must incorporate a high-pass filter to reflect back the fundamental mode into the cavity. In this paper, we show the good frequency response map obtained from our filter's design. We extract a circuit diagram from the microwave elements that simulate well the frequency spectrum of the finalized filter. We also demonstrate that the power dissipation on the filter over its frequency range is small enough for cryogenic cooling.
Date: May 23, 2010
Creator: Wu, Q. & Ben-Zvi, Ilan
Object Type: Article
System: The UNT Digital Library
Electron Cloud at Low Emittance in CesrTA (open access)

Electron Cloud at Low Emittance in CesrTA

The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.
Date: May 23, 2010
Creator: Alexander, J. P.; Billing, M. G.; Calvey, J.; Crittenden, J. A.; Dugan, G.; Eggert, N. et al.
Object Type: Article
System: The UNT Digital Library
Bexar County Parking Garage Photovoltaic Panels (open access)

Bexar County Parking Garage Photovoltaic Panels

The main objective of the Bexar County Parking Garage Photovoltaic (PV) Panel project is to install a PV System that will promote the use of renewable energy. This project will also help sustain Bexar County ongoing greenhouse gas emissions reduction and energy efficiency goals. The scope of this project includes the installation of a 100-kW system on the top level of a new 236,285 square feet parking garage. The PV system consists of 420 solar panels that covers 7,200 square feet and is tied into the electric-grid. It provides electricity to the office area located within the garage. The estimated annual electricity production of the PV system is 147,000 kWh per year.
Date: January 23, 2012
Creator: Weir, Golda
Object Type: Report
System: The UNT Digital Library
Estimation of Steady-State and Transcient Power Distributions for the RELAP Analyses of the 1963 Loss-Of-Flow and Loss-Of-Pressure Tests at br2. (open access)

Estimation of Steady-State and Transcient Power Distributions for the RELAP Analyses of the 1963 Loss-Of-Flow and Loss-Of-Pressure Tests at br2.

To support the safety analyses required for the conversion of the Belgian Reactor 2 (BR2) from highly-enriched uranium (HEU) to low-enriched uranium (LEU) fuel, the simulation of a number of loss-of-flow tests, with or without loss of pressure, has been undertaken. These tests were performed at BR2 in 1963 and used instrumented fuel assemblies (FAs) with thermocouples (TC) imbedded in the cladding as well as probes to measure the FAs power on the basis of their coolant temperature rise. The availability of experimental data for these tests offers an opportunity to better establish the credibility of the RELAP5-3D model and methodology used in the conversion analysis. In order to support the HEU to LEU conversion safety analyses of the BR2 reactor, RELAP simulations of a number of loss-of-flow/loss-of-pressure tests have been undertaken. Preliminary analyses showed that the conservative power distributions used historically in the BR2 RELAP model resulted in a significant overestimation of the peak cladding temperature during the transient. Therefore, it was concluded that better estimates of the steady-state and decay power distributions were needed to accurately predict the cladding temperatures measured during the tests and establish the credibility of the RELAP model and methodology. The new approach ('best …
Date: May 23, 2011
Creator: Dionne, B. & Tzanos, C. P. (Nuclear Engineering Division)
Object Type: Report
System: The UNT Digital Library
Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen (open access)

Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen

We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of {sup 136}Xe. The measured two-neutrino double-beta decay half-life of {sup 136}Xe is T{sup 2{nu}}{sub 1/2} = 2:38 {+-}#6; 0:02(stat)#6;{+-}0.14(syst)#2;x10{sup 21} yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, T{sup 0{nu}}{sub 1/2} > 5.7 x#2; 10{sup 24} yr at 90% C.L.
Date: January 23, 2012
Creator: Collaboration, KamLAND-Zen; Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K. et al.
Object Type: Article
System: The UNT Digital Library
Uncompensated magnetization and exchange-bias field in La0.7Sr0.3MnO3/YMnO3 bilayers: The influence of the ferromagnetic layer (open access)

Uncompensated magnetization and exchange-bias field in La0.7Sr0.3MnO3/YMnO3 bilayers: The influence of the ferromagnetic layer

None
Date: May 23, 2011
Creator: Zandalazini, C.; Esquinazi, P.; Bridoux, G.; Barzola-Quiquia, J.; Ohldag, H. & Arenholz, E.
Object Type: Article
System: The UNT Digital Library
Comment on Li pellet Conditioning in TFTR (open access)

Comment on Li pellet Conditioning in TFTR

Li pellet conditioning in TFTR results in a reduction of the edge electron density which allows increased neutral beam penetration, central heating, and fueling. Consequently the temperature profiles became more peaked with higher central Ti, Te, and neutron emission rates.
Date: May 23, 2011
Creator: Budny, R.V.
Object Type: Report
System: The UNT Digital Library