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Two implementations of shared virtual space environments.

Description: While many issues in the area of virtual reality (VR) research have been addressed in recent years, the constant leaps forward in technology continue to push the field forward. VR research no longer is focused only on computer graphics, but instead has become even more interdisciplinary, combining the fields of networking, distributed computing, and even artificial intelligence. In this article we discuss some of the issues associated with distributed, collaborative virtual reality, as well as … more
Date: January 13, 1998
Creator: Disz, T. L.
Partner: UNT Libraries Government Documents Department
open access

Thermophotovoltaic Cell Temperature Measurement Issues

Description: The power produced by photovoltaic devices changes with temperature, ranging from 0.1% to nearly 1% per degrees Celsius depending on the structure. The temperature across the surface of TPV cells will vary depending on the amount of absorbed power. Thus the temperature over a region of a wafer where there is no cell will be different from a region of the wafer containing a cell with an antireflection coating and back surface reflector. Vacuum hold-downs or back surface probes may result in loca… more
Date: November 13, 1998
Creator: Emery, K. & Moriarty, T.
Partner: UNT Libraries Government Documents Department
open access

Detector limitations, STAR

Description: Every detector has limitations in terms of solid angle, particular technologies chosen, cracks due to mechanical structure, etc. If all of the presently planned parts of STAR [Solenoidal Tracker At RHIC] were in place, these factors would not seriously limit our ability to exploit the spin physics possible in RHIC. What is of greater concern at the moment is the construction schedule for components such as the Electromagnetic Calorimeters, and the limited funding for various levels of triggers.
Date: July 13, 1998
Creator: Underwood, D. G.
Partner: UNT Libraries Government Documents Department
open access

Comparison of measured and calculated composition of irradiated EBR-II blanket assemblies.

Description: In anticipation of processing irradiated EBR-II depleted uranium blanket subassemblies in the Fuel Conditioning Facility (FCF) at ANL-West, it has been possible to obtain a limited set of destructive chemical analyses of samples from a single EBR-II blanket subassembly. Comparison of calculated values with these measurements is being used to validate a depletion methodology based on a limited number of generic models of EBR-II to simulate the irradiation history of these subassemblies. Initial … more
Date: July 13, 1998
Creator: Grimm, K. N.
Partner: UNT Libraries Government Documents Department
open access

Experimental observations to the electrical field for electrorefining of spent nuclear fuel in the Mark-IV electrorefiner.

Description: Experimental results from the pilot scale electrorefiner (Mark-IV ER) treating spent nuclear fuel are reported in this article. The electrorefining processes were carried out in a LiCl-KCl-UCl{sub 3} electrolyte. It has been noted that spool of molten cadmium below the electrolyte plays an important role in the electrorefining operations. In addition, formations of electrical shorting path between anode baskets and the electrorefiner vessel were observed, which lessened the uranium dissolution … more
Date: May 13, 1998
Creator: Li, S. X.
Partner: UNT Libraries Government Documents Department
open access

Massively Parallel Linear Stability Analysis with P_ARPACK for 3D Fluid Flow Modeled with MPSalsa

Description: We are interested in the stability of three-dimensional fluid flows to small dkturbances. One computational approach is to solve a sequence of large sparse generalized eigenvalue problems for the leading modes that arise from discretizating the differential equations modeling the flow. The modes of interest are the eigenvalues of largest real part and their associated eigenvectors. We discuss our work to develop an effi- cient and reliable eigensolver for use by the massively parallel simulatio… more
Date: October 13, 1998
Creator: Lehoucq, R. B. & Salinger, A. G.
Partner: UNT Libraries Government Documents Department
open access

Superconducting nanostructured materials.

Description: Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical c… more
Date: July 13, 1998
Creator: Metlushko, V.
Partner: UNT Libraries Government Documents Department
open access

Modeling tritium behavior in Li{sub 2}ZrO{sub 3}.

Description: Lithium metazirconate (Li{sub 2}ZrO{sub 3}) is a promising tritium breeder material for fusion reactors because of its excellent tritium release characteristics. In particular, for water-cooled breeding blankets (e.g., ITER), Li{sub 2}ZrO{sub 3} is appealing from a design perspective because of its good tritium release at low operating temperatures. The steady-state and transient tritium release/retention database for Li{sub 2}ZrO{sub 3} is reviewed, along with conventional diffusion and first-… more
Date: January 13, 1998
Creator: Billone, M. C.
Partner: UNT Libraries Government Documents Department
open access

Marginal Stability of D-Wave Superconductor: Spontaneous P and T Violation in the Presence of Magnetic Impurities

Description: The author argues that the d{sub x{sup 2}{minus}y{sup 2}}-wave superconductor is marginally stable in the presence of external perturbations. Subjected to the external perturbations by magnetic impurities, it develops a secondary component of the gap, complex d{sub xy}, to maximize the coupling to impurities and lower the total energy. The secondary d{sub xy} component exists at high temperatures and produces the full gap {approximately} 20K in the single particle spectrum around each impurity,… more
Date: May 13, 1998
Creator: Balatsky, A. V.
Partner: UNT Libraries Government Documents Department
open access

Next-generation laser for inertial confinement fusion

Description: We are developing and building the ''Mercury'' laser system as the first in a series of a new generation of diode-pumped solid-state lasers (DPSSL) for advanced high energy density (HED) physics experiments at LLNL. Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced Inertial Confinement Fusion (ICF) goals. Primary performance goals include 10% efficiencies at 10 Hz and a <10 ns pulse with l {omega} energies of 100 J and with 2 {omega}… more
Date: March 13, 1998
Creator: Marshall, C.; Bibeau, C.; Bayramian, A.; Beach, R.; Ebbers, C. A.; Emanuel, M. et al.
Partner: UNT Libraries Government Documents Department
open access

Recent advances in indirect drive ICF target physics at LLNL

Description: In preparation for ignition on the National Ignition Facility, the Lawrence Livermore National Laboratory� s Inertial Confinement Fusion Program, working in collaboration with Los Alamos National Laboratory, Commissariat a 1� Energie Atomique (CEA), and Laboratory for Laser Energetics at the University of Rochester, has performed a broad range of experiments on the Nova and Omega lasers to test the fundamentals of the NIF target designs. These studies have refined our understanding of the impor… more
Date: January 13, 1998
Creator: Bernat, T. P.; Collins, G. W.; Haan, S.; Hammel, B. A.; Landen, O. L.; MacGowan, B. J. et al.
Partner: UNT Libraries Government Documents Department
open access

New Neutron Rich Nuclei Near {sup 208}Pb

Description: The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may tr… more
Date: November 13, 1998
Creator: Aeystoe, J.; Andreyev, A.; Evensen, A.-H.; Hoff, P.; Huhta, M.; Huyse, M. et al.
Partner: UNT Libraries Government Documents Department
open access

Stability of regional configurations

Description: At moderate force levels the first strike stability index is proportional to the first strike cost, so as the attacker minimizes attack costs, he automatically minimizes stability. Weapons grow rapidly and saturate to levels comparable to the number of value targets held at risk. This growth could appear destabilizing to dominant regional powers, whose response could in turn appear threatening to the major nuclear powers, which could slow or halt efforts towards deep reductions. The fundamental… more
Date: August 13, 1998
Creator: Canavan, G. H.
Partner: UNT Libraries Government Documents Department
open access

EM-PIC simulations of e-beam interaction with field emitted ions from bremsstrahlung targets

Description: We investigate electron beam defocusing caused by field emitted ions from the bremsstrahlung target of a radiography machine using fully electromagnetic particle-in-cell simulations. This possibly deleterious effect is relevant to both current radiography machines (FXR) and machines being built (DARHT-2) or planned (AHF). A simple theory of the acceleration of ions desorbed from the heated target, and subsequent beam defocusing due to partial charge neutralization is in reasonable agreement wit… more
Date: August 13, 1998
Creator: Rambo, P. W., LLNL
Partner: UNT Libraries Government Documents Department
open access

Proton Radioactivity Measurements at HRIBF: Ho, Lu, and Tm Isotopes

Description: Two new isotopes, {sup 145}Tm and {sup 140}Ho and three isomers in previously known isotopes, {sup 141m}Ho, {sup 150m}Lu and {sup 151m}Lu have been discovered and studied via their decay by proton emission. These proton emitters were produced at the Holifield Radioactive Ion Beam Facility (HRIBF) by heavy-ion fusion-evaporation reactions, separated in A/Q with a recoil mass spectrometer (RMS), and detected in a double-sided silicon strip detector (DSSD). The decay energy and half-life was measu… more
Date: November 13, 1998
Creator: Akovali, Y.; Batchelder, J. C.; Bingham, C. R.; Davinson, T.; Ginter, T. N.; Gross, C. J. et al.
Partner: UNT Libraries Government Documents Department
open access

Predicting flammable gas mixtures in Hanford double-contained receiver tanks

Description: This study presents a methodology to estimate the maximum concentrations of flammable gases (ammonia, hydrogen, and methane) which could exist in the vapor space of a double-contained receiver tank (DCRT). DCRTs are temporary storage tanks which receive highly radioactive liquid wastes from salt well pumping of Hanford single-shell tanks (SST). The methodology of this study could be used in other applications involving the storage and transfer of radioactive liquid wastes which generate or cont… more
Date: May 13, 1998
Creator: Hedengren, D.C.
Partner: UNT Libraries Government Documents Department
open access

The Use of X-Ray Microbeams in Materials Science

Description: Most materials are heterogeneous on mesoscopic length scales (tenths-to-tens of microns), and materials properties depend critically on mesoscopic structures such as grain sizes, texture, and impurities. The recent availability of intense, focused x-ray microbeams at synchrotron facilities has enabled new techniques for mesoscale materials characterization. We describe instrumentation and experiments on the MHATT-CAT and UNICAT undulator beamlines at the Advanced Photon Source which use micron … more
Date: October 13, 1998
Creator: Budai, J. D.; Chung, J.-S.; Ice, G. E.; Larson, B. C.; Lowe, W. P.; Norton, D. P. et al.
Partner: UNT Libraries Government Documents Department
open access

Fabrication and testing of optics for EUV projection lithography

Description: Extreme Ultraviolet Lithography (EUVL) is a leading candidate as a stepper technology for fabricating the ``0.1 {micro}m generation`` of microelectronic circuits. EUVL is an optical printing technique qualitatively similar to Deep UV Lithography (DUVL), except that 11-13nm wavelength light is used instead of 193-248nm. The feasibility of creating 0.l{micro}m features has been well-established using small-field EWL printing tools, and development efforts are currently underway to demonstrate tha… more
Date: March 13, 1998
Creator: Taylor, J. S.
Partner: UNT Libraries Government Documents Department
open access

Improving analytical understanding through the addition of information: Bayesian and hybrid mathematics approaches

Description: Safety analysts frequently must provide results that are based on sparse (or even no) data. When data (or more data) become available, it is important to utilize the new information optimally in improving the analysis results. Two methods for accomplishing this purpose are Bayesian analysis, where "prior" probability distributions are modified to become "posterior" distributions based on the new data, and hybrid (possibilistic/probabilistic analysis) where possibilistic "membership" portrays th… more
Date: September 13, 1998
Creator: Cooper, J.A. & Diegert, K.V.
Partner: UNT Libraries Government Documents Department
open access

The Performance of the HRIBF Recoil Mass Spectrometry

Description: The Recoil Mass Spectrometer (RMS) is a mass separator located at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. This paper describes the RMS, its performance, its detector systems, and discusses some experiments to illustrate its capabilities.
Date: November 13, 1998
Creator: Ginter, T. N.
Partner: UNT Libraries Government Documents Department
open access

Hydrogen peroxide propulsion for smaller satellites (SSC98-VIII-1)

Description: As satellite designs shrink, providing maneuvering and control capability falls outside the realm of available propulsion technology. While cold gas has been used on the smallest satellites, hydrogen peroxide propellant is suggested as the next step in performance and cost before hydrazine. Minimal toxicity and a small scale enable benchtop propellant preparation and development testing. Progress toward low-cost thrusters and self-pressurizing tank systems is described.
Date: July 13, 1998
Creator: Whitehead, J. C.
Partner: UNT Libraries Government Documents Department
open access

Linear dichroism and resonant photoemission in Gd 011

Description: Magnetic Linear Dichroism in Angular Distributions (MLDAD) from Photoelectron Emission was used to probe the nature of Resonant Photoemission. Gd 5p and Gd 4f emission were investigated. Using novel theoretical simulations, we were able to show that temporal matching is a requirement for ``True`` Resonant Photoemission, where the Resonant Photoemission retains the characteristics of Photoelectron Emission.
Date: May 13, 1998
Creator: Mishra, S. R.; Cummins, T. R.; Gammon, W. J.; van der Laan, G.; Goodman, K. W. & Tobin, J. G.
Partner: UNT Libraries Government Documents Department
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