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Many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions (open access)

Many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions

This article discusses many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions.
Date: May 31, 2005
Creator: Ilton, Eugene S. & Bagus, Paul S.
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
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
Status of Continuum Edge Gyrokinetic Code Physics Development (open access)

Status of Continuum Edge Gyrokinetic Code Physics Development

We are developing an edge gyro-kinetic continuum simulation code to study the boundary plasma over a region extending from inside the H-mode pedestal across the separatrix to the divertor plates. A 4-D ({psi}, {theta}, {epsilon}, {mu}) version of this code is presently being implemented, en route to a full 5-D version. A set of gyrokinetic equations[1] are discretized on computational grid which incorporates X-point divertor geometry. The present implementation is a Method of Lines approach where the phase-space derivatives are discretized with finite differences and implicit backwards differencing formulas are used to advance the system in time. A fourth order upwinding algorithm is used for particle cross-field drifts, parallel streaming, and acceleration. Boundary conditions at conducting material surfaces are implemented on the plasma side of the sheath. The Poisson-like equation is solved using GMRES with multi-grid preconditioner from HYPRE. A nonlinear Fokker-Planck collision operator from STELLA[2] in ({nu}{sub {parallel}},{nu}{sub {perpendicular}}) has been streamlined and integrated into the gyro-kinetic package using the same implicit Newton-Krylov solver and interpolating F and dF/dt|{sub coll} to/from ({epsilon}, {mu}) space. With our 4D code we compute the ion thermal flux, ion parallel velocity, self-consistent electric field, and geo-acoustic oscillations, which we compare with standard neoclassical …
Date: May 31, 2005
Creator: Xu, X Q; Xiong, Z; Dorr, M R; Hittinger, J A; Kerbel, G D; Nevins, W M et al.
System: The UNT Digital Library
Structural Studies on Dy to 119 GPa and Applications to Lanthanide Systematics (open access)

Structural Studies on Dy to 119 GPa and Applications to Lanthanide Systematics

The Rare Earth elements (REE) are known to undergo crystallographic as well as electronic structure changes with applied pressure. On increasing pressure, the trivalent lanthanides follow the sequence hcp {yields} Sm-type {yields} dhcp {yields} fcc {yields} dfcc. In this report we present room-temperature high-pressure x-ray diffraction data for Dy as well as our observations on the post-dfcc phases and concomitant volume changes in the heavy REE.
Date: May 31, 2005
Creator: Patterson, J & Akella, J
System: The UNT Digital Library
Class B0631+519: Last of the Class Lenses (open access)

Class B0631+519: Last of the Class Lenses

We report the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the VLA, MERLIN and the VLBA reveals a doubly-imaged flat-spectrum radio core, a doubly-imaged steep-spectrum radio lobe and possible quadruply-imaged emission from a second lobe. The maximum separation between the lensed images is 1.16 arcsec. High resolution mapping with the VLBA at 5 GHz resolves the most magnified image of the radio core into a number of sub-components spread across approximately 20 mas. No emission from the lensing galaxy or an odd image is detected down to 0.31 mJy (5{sigma}) at 8.4 GHz. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as previously discovered by optical spectroscopy. We find that the foreground galaxy at z=0.0896 is a small irregular, and that the other, at z=0.6196 is a massive elliptical which appears to contribute the majority of the lensing effect. The host galaxy of the lensed source is detected in the HST near-infrared imaging as a set of arcs, which form a nearly complete Einstein ring. Mass modeling using non-parametric techniques can reproduce the near-infrared observations and …
Date: May 31, 2005
Creator: York, Tom; Jackson, N.; Browne, I. W. A.; Koopmans, L. V. E.; McKean, J. P.; Norbury, M. A. et al.
System: The UNT Digital Library
Workforce Planning and Analytics (open access)

Workforce Planning and Analytics

None
Date: May 31, 2005
Creator: More, J & Presta, C
System: The UNT Digital Library
Accounting Procedures for Foreign-owned Nuclear Material Located Temporarily in the Russian Federation (open access)

Accounting Procedures for Foreign-owned Nuclear Material Located Temporarily in the Russian Federation

None
Date: May 31, 2005
Creator: Pitel, V. A.; Kasumova, L. A. & Babcock, R. A.
System: The UNT Digital Library