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A Load Balanced Domain Decomposition Method Using Wavelet Analysis (open access)

A Load Balanced Domain Decomposition Method Using Wavelet Analysis

Wavelet Analysis provides an orthogonal basis set which is localized in both the physical space and the Fourier transform space. We present here a domain decomposition method that uses wavelet analysis to maintain roughly uniform error throughout the computation domain while keeping the computational work balanced in a parallel computing environment.
Date: May 31, 2001
Creator: Jameson, L; Johnson, J & Hesthaven, J
System: The UNT Digital Library
Reconstruction of FXR Beam Conditions (open access)

Reconstruction of FXR Beam Conditions

Beam-envelope radius, envelope angle, and beam emittance can be derived from measurements of beam radius for at least three different transport conditions. We have used this technique to reconstruct exit parameters from the FXR injector and accelerator. We use a diamagnetic loop (DML) to measure the magnetic moment of the high current beam. With no assumptions about radial profile, we can derive the beam mean squire radius from the moment under certain easily met conditions. Since it is this parameter which is required for the reconstruction, it is evident that the DML is the ideal diagnostic for this technique. The simplest application of this technique requires at least three shots for a reconstruction but in reality requires averaging over many more shots because of shot to shot variation. Since DML measurements do not interfere with the beam, single shot time resolved measurements of the beam parameters appear feasible if one uses an array of at least three DMLs separated by known transport conditions.
Date: May 31, 2001
Creator: Nexen, W E; Scarpetti, R D & Zentler, J
System: The UNT Digital Library
Small Nuclear Technology and Market Entry (open access)

Small Nuclear Technology and Market Entry

An overview of energy-system projections into the new century leads to the conclusion that nuclear power will play a significant role. How significant a role will be determined by the marketplace. Within the range of nuclear-power technologies available, small nuclear-power plants of innovative design appear to fit the needs of a number of developing nations and states. Under similar financing options used by the airline industry and others, the capital requirement barrier that puts the nuclear industry at a disadvantage in deregulated markets could be reduced. These plants have the potential advantage of modularity, are proliferation-resistant, incorporate passive safety features, minimize waste, and could be cost-competitive with fossil-fuel plants.
Date: May 31, 2002
Creator: Stewart, Jeffrey S.; Schock, Robert N.; Brown, Neil W. & Smith, Craig F.
System: The UNT Digital Library
Pressure Wave Measurements from Thermal Cook-Off of an HMX Based High Explosive PBX 9501 (open access)

Pressure Wave Measurements from Thermal Cook-Off of an HMX Based High Explosive PBX 9501

A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.
Date: May 31, 2001
Creator: Garcia, F.; Forbes, J. W.; Tarver, Craig M.; Urtiew, P. A.; Greenwood, D. W. & Vandersall, K. S.
System: The UNT Digital Library
Electromechanical Battery Program at the Lawrence Livermore National Laboratory (open access)

Electromechanical Battery Program at the Lawrence Livermore National Laboratory

New materials and new design concepts are being incorporated in a new approach to an old idea -- flywheel energy storage -- to create an important alternative to the electrochemical storage battery for use in electric vehicles or for stationary applications, such as computer back-up power or utility load-leveling. We visualize such EMBs (electromechanical batteries) as being modular in character, with small (1--5 kWh) modules being used for power-conditioning and for vehicular use, and paralleled 25 kWh modules being used for bulk storage, i.e., load-leveling, applications. In a funded program at the Laboratory two fractional kWh, 200 kW (design peak power) modules have been constructed and subjected to shake-down testing. Their design for high peak power was prompted by awareness of a particular commercial need, as a component in a power-line conditioning device. In addition to such stationary applications, the high power capability of our EMB designs makes them attractive for use in hybrid-electric vehicles. Important elements of the LLNL program include the development of passive magnetic bearings and the application of new high-efficiency permanent magnet arrays to an ironless generator/motor. Use of these particular elements, together with a multi-ring design for the flywheel rotor, is particularly conducive to a …
Date: May 31, 1994
Creator: Post, R. F.; Bender, D. A. & Merritt, B. T.
System: The UNT Digital Library
Accelerator-Based Surface Chemistry by Combined Time-of-Flight Mass Spectrometry (TOF-MS) and Particle-Induced X-Ray Emission (PIXE) (open access)

Accelerator-Based Surface Chemistry by Combined Time-of-Flight Mass Spectrometry (TOF-MS) and Particle-Induced X-Ray Emission (PIXE)

We describe the development of a new capability for performing microscopic chemical analysis in the near surface of a sample. The technology uses a focused high-energy ion beam from an accelerator to cause characteristic elemental x-rays to be emitted and, simultaneously, molecules and fragments to be desorbed from the surface of the sample. Spectroscopic analysis of the fluoresced x-rays provides quantitative trace element information of the sample volume probed by the beam. The elemental data are subsequently used to identify peaks in the mass analysis of the desorbed species, thereby providing a detailed description of the local surface chemistry. High-resolution (micron-scale) chemical imaging is possible by scanning the beam over the sample.
Date: May 31, 2002
Creator: Morse, D. H.; Grant, P. G.; Antolak, A. J.; Sproch, N. & Fernando, Q.
System: The UNT Digital Library
Search for the Inclusive B to D Gamma Decay at BaBar (open access)

Search for the Inclusive B to D Gamma Decay at BaBar

None
Date: May 31, 2013
Creator: Bard, Deborah & U., /Edinburgh
System: The UNT Digital Library
Loss of Migratory Traditions Makes the Endangered Patagonian Huemul Deer a Year-Round Refugee in Its Summer Habitat (open access)

Loss of Migratory Traditions Makes the Endangered Patagonian Huemul Deer a Year-Round Refugee in Its Summer Habitat

This article analyzes the historical spatiotemporal behavior of the huemul (Hippocamelus bisulcus), an endangered deer endemic to Patagonia. Losing migratory traditions is a major threat, and may explain their presently prevalent skeletal diseases, reduced longevity, and lacking recolonizations for most remaining huemul subpopulations.
Date: May 31, 2022
Creator: Flueck, Werner T.; Smith-Flueck, Jo Anne M.; Escobar, Miguel E.; Zuliani, Melina; Fuchs, Beat; Geist, Valerius et al.
System: The UNT Digital Library
Exploring the Potential Impact of Artificial Intelligence (AI) on International Students in Higher Education: Generative AI, Chatbots, Analytics, and International Student Success (open access)

Exploring the Potential Impact of Artificial Intelligence (AI) on International Students in Higher Education: Generative AI, Chatbots, Analytics, and International Student Success

Article asserts that international students face unique challenges in pursuing higher education in a foreign country. To address these challenges and enhance their academic experience, higher education institutions are increasingly exploring the use of artificial intelligence (AI) applications. The research paper explores various AI applications, such as personalized learning experiences, adaptive testing, predictive analytics, and chatbots for learning and research.
Date: May 31, 2023
Creator: Wang, Ting; Lund, Brady D.; Marengo, Agostino; Pagano, Alessandro; Mannuru, Nishith Reddy; Teel, Zoë A. et al.
System: The UNT Digital Library
Atomic Phase Shifts In Mixed-Glass, Multi-Petawatt Laser Systems (open access)

Atomic Phase Shifts In Mixed-Glass, Multi-Petawatt Laser Systems

None
Date: May 31, 2011
Creator: Filip, C V
System: The UNT Digital Library
Simulation of Aluminum Combustion and PETN Afterburning in a Confined Explosion (open access)

Simulation of Aluminum Combustion and PETN Afterburning in a Confined Explosion

None
Date: May 31, 2007
Creator: Kuhl, A L; Bell, J B; Beckner, V E & Khasainov, B
System: The UNT Digital Library
Afterburning and Combustion in Explosions in Barometric Calorimeters (open access)

Afterburning and Combustion in Explosions in Barometric Calorimeters

None
Date: May 31, 2007
Creator: Reichenbach, H; Neuwald, P & Kuhl, A L
System: The UNT Digital Library
The Young Planet-Mass Object 2M1207b: A Cool, Cloudy, and Methane-Poor Atmosphere (open access)

The Young Planet-Mass Object 2M1207b: A Cool, Cloudy, and Methane-Poor Atmosphere

None
Date: May 31, 2011
Creator: Barman, T. S.; Macintosh, B. A.; Konopacky, Q. M. & Marois, C.
System: The UNT Digital Library
The Last of the Finite Loop Amplitudes in QCD (open access)

The Last of the Finite Loop Amplitudes in QCD

We use on-shell recursion relations to determine the one-loop QCD scattering amplitudes with a massless external quark pair and an arbitrary number (n - 2) of positive-helicity gluons. These amplitudes are the last of the unknown infrared- and ultraviolet-finite loop amplitudes of QCD. The recursion relations are similar to ones applied at tree level, but contain new non-trivial features corresponding to poles present for complex momentum arguments but absent for real momenta. We present the relations and the compact solutions to them, valid for all n. We also present compact forms for the previously-computed one-loop n-gluon amplitudes with a single negative helicity and the rest positive helicity.
Date: May 31, 2005
Creator: Bern, Zvi; Dixon, Lance J. & Kosower, David A.
System: The UNT Digital Library
TransCom model simulations of CH4 and related species: Linking transport, surface flux and chemical loss with CH4 variablity in troposphere and lower stratosphere (open access)

TransCom model simulations of CH4 and related species: Linking transport, surface flux and chemical loss with CH4 variablity in troposphere and lower stratosphere

None
Date: May 31, 2011
Creator: Patra, P. K.; Houweling, S.; Krol, M.; Bousquet, P.; Belikov, D.; Bergmann, D. et al.
System: The UNT Digital Library
US-Russian Collaboration in Nuclear Forensics - INMM 2011 (open access)

US-Russian Collaboration in Nuclear Forensics - INMM 2011

None
Date: May 31, 2011
Creator: Kristo, M J
System: The UNT Digital Library
Optimization of Direct Ionization of CO2 by Controlling the Gas Flow inside of a Beam-Target (open access)

Optimization of Direct Ionization of CO2 by Controlling the Gas Flow inside of a Beam-Target

None
Date: May 31, 2011
Creator: Salazar Quintero, G A & Ognibene, T
System: The UNT Digital Library
Simulation of Hypervelocity Penetration in Limestone (open access)

Simulation of Hypervelocity Penetration in Limestone

A parameter study was performed to examine the (shock) damage obtained with long-rod and spherical mono-material penetrators impacting two varieties of limestone. In all cases, the impacts were assumed to be normal to the plane of the rock and at zero angle of attack (in the case of the rods). Impact velocities ranged to 15 km/s but most calculations were performed at 4 and 6 km/s and the penetrator mass was fixed at 1000 kg. For unlined underground structures, incipient damage was defined to occur when the peak stress, {sigma}{sub pk}, exceeds 1 kb (100 MPa) and the applied impulse per unit area, I{sub pk}, exceeds 1 ktap (1 kb-{micro}s). Severe damage was assumed to occur when {sigma}{sub pk} exceeds 1 kb and I{sub pk} exceeds 1000 ktaps. Using the latter definition it was found that severe damage in hard, non-porous limestone with spherical impactors extended to a depth of 9 m on-axis for an impact velocity of 4 km/s and 12 m at 6 km/s. Cylinders with length-to-diameter (L/D) ratio of 8.75 achieved depth to severe damage of 23 m and 40 m, respectively under the same conditions. For a limestone medium with 2% initial gas porosity, the latter …
Date: May 31, 2005
Creator: Antoun, T; Glenn, L; Walton, O; Goldstein, P; Lomov, I & Liu, B
System: The UNT Digital Library
Simulation of penetration into porous geologic media (open access)

Simulation of penetration into porous geologic media

We present a computational study on the penetration of steel projectiles into porous geologic materials. The purpose of the study is to extend the range of applicability of a recently developed constitutive model to simulations involving projectile penetration into geologic media. The constitutive model is non-linear, thermodynamically consistent, and properly invariant under superposed rigid body motions. The equations are valid for large deformations and they are hyperelastic in the sense that the stress tensor is related to a derivative of the Helmholtz free energy. The model uses the mathematical structure of plasticity theory to capture the basic features of the mechanical response of geological materials including the effects of bulking, yielding, damage, porous compaction and loading rate on the material response. The new constitutive model has been successfully used to simulate static laboratory tests under a wide range of triaxial loading conditions, and dynamic spherical wave propagation tests in both dry and saturated geologic media.
Date: May 31, 2005
Creator: Vorobiev, O Y; Liu, B T; Lomov, I N & Antoun, T
System: The UNT Digital Library
Parallel Measurement and Modeling of Transport in the Darht Ii Beamline on Eta Ii (open access)

Parallel Measurement and Modeling of Transport in the Darht Ii Beamline on Eta Ii

To successfully tune the DARHT II transport beamline requires the close coupling of a model of the beam transport and the measurement of the beam observables as the beam conditions and magnet settings are varied. For the ETA II experiment using the DARHT II beamline components this was achieved using the SUICIDE (Simple User Interface Connecting to an Integrated Data Environment) data analysis environment and the FITS (Fully Integrated Transport Simulation) model. The SUICIDE environment has direct access to the experimental beam transport data at acquisition and the FITS predictions of the transport for immediate comparison. The FITS model is coupled into the control system where it can read magnet current settings for real time modeling. We find this integrated coupling is essential for model verification and the successful development of a tuning aid for the efficient convergence on a useable tune. We show the real time comparisons of simulation and experiment and explore the successes and limitations of this close coupled approach.
Date: May 31, 2005
Creator: Chambers, F. W.; Raymond, B. A.; Falabella, S.; Lee, B. S.; Richardson, R. A.; Weir, J. T. et al.
System: The UNT Digital Library
Optimum model-E-GAMS for Distributed Energy System by Using GAMSMethod (open access)

Optimum model-E-GAMS for Distributed Energy System by Using GAMSMethod

DER-CAM Developed by the Lawrence Berkeley National Laboratory (LBNL), is an optimization tool for DER technology selection. However it can not be simply applied to the Japanese case because of the different climate and the utility tariff. This research aims to develop an optimization tool for distributed energy for Japanese buildings using GAMS, a high-level modeling system for mathematical programming and optimization. This paper describes how we apply and demonstrate the tool to the energy center at Kitakyushu Research city, where has installed a fuel cell and a gas engine. An analysis has also been conducted to see how the utility tarriff and the equipment efficiency can affect the operation of the DER system.
Date: May 31, 2005
Creator: Yang, Yongwen; Gao, Weijun; Ruan, Yingjun; Zhou, Nan; Xuan, Ji & Marnay, Chris
System: The UNT Digital Library
Bank Upgrade for Sspx at Llnl (open access)

Bank Upgrade for Sspx at Llnl

A new 5kV, 1.5MJ modular capacitor bank has been designed for the Sustained Spheromak Physics Experiment (SSPX) at LLNL. The new bank consists of thirty 4mF capacitors that are independently controlled by light-triggered thyristors. By closing all switches simultaneously, the bank will provide a mega-ampere discharge. The new bank will also allow additional capabilities to SSPX, including higher peak gun current, longer current pulses, and multi-pulse plasma buildup. Experiment results for a single stage prototype will be presented, deliver a single large current spike, or, switches can be triggered in sequence to deliver a longer lower current pulse. Multiple pulses can be created by triggering sections of the modular bank in intervals.
Date: May 31, 2005
Creator: Marchiano, M. M.; Cook, E. G.; Geer, R. W.; Kemptner, R. O.; McLean, H. S.; Martovetsky, N. N. et al.
System: The UNT Digital Library
Electronic Properties of LiFePO4 and Li doped LiFePO4 (open access)

Electronic Properties of LiFePO4 and Li doped LiFePO4

LiFePO{sub 4} has several potential advantages in comparison to the transition metal oxide cathode materials used in commercial lithium-ion batteries. However, its low intrinsic electronic conductivity ({approx} 10{sup -9} S/cm) is problematic. We report here a study by soft x-ray absorption/emission spectroscopy of the electronic properties of undoped LiFePO{sub 4} and Li-doped LiFePO{sub 4} in which Li{sup +} ions are substituted for Fe{sup 2+} ions in an attempt to increase the intrinsic electronic conductivity. The conductivities of the Li{sub 1+x}Fe{sub 1-x}PO{sub 4} samples were, however, essentially unchanged from that of the undoped LiFePO{sub 4}. Nonetheless, evidence for changing the electronic properties of LiFePO{sub 4} by doping with excess Li+ was observed by the XAS/XES spectroscopy. New pre-edge features the O-1s XAS spectrum of Li{sub 1.05}Fe{sub 0.95}PO4 is a direct indication that the charge compensation for substitution of Fe{sup 2+} by Li{sup +} resides in the unoccupied O-2p orbitals. A charge transfer (CT) excitation was also observed in the doped material implying that the unoccupied O-2p orbitals created by doping are strongly hybridized with unoccupied Fe-3d orbitals of neighboring sites. However, the strong covalent bonding within the (PO{sub 4}){sup 3-} anions and the large separation of the Fe cations means that …
Date: May 31, 2006
Creator: Allen, J.L.; Zhuang, G.V.; Ross, P.N.; Guo, J.-H. & Jow, T.R.
System: The UNT Digital Library