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Atom-in-jellium models (open access)

Atom-in-jellium models

The author describes in this paper the atom-in-jellium calculations he has been doing over the last ten years. He tries to emphasize reasons for doing this sort of calculations and why he devised a model which is different in some respects from others.
Date: April 26, 1985
Creator: Liberman, D.A.
System: The UNT Digital Library
Executive committee report: geotechnical instrumentation working group meeting (open access)

Executive committee report: geotechnical instrumentation working group meeting

Responding to the widespread need for the geotechnical community to discuss instrumentation for nuclear waste repositories, a meeting was held December 2 and 3, 1981, in Denver, Colorado. This report gives the group's consensus recommendations to aid in making decisions for development of instrumentation for future repository work. The main conclusions of the working group meeting were as follows: (1) monitoring of geotechnical parameters in nuclear waste repositories will be necessary to meet licensing requirements; (2) currently available instruments are underdeveloped for this monitoring; (3) research and development to provide adequate instrumentation will need to be performed under federal sponsorship by national laboratories, universities, contractors, and consultants; and (4) a NASA-type reliability program is needed to meet the quality assurance, durability, calibration, and time schedule demands of geotechnical instrumentation development. This will require significant financial commitments from the federal sector.
Date: April 26, 1982
Creator: Wilder, D. G.; Rogue, F.; Beloff, W. R.; Binnall, E. & Gregory, E. C.
System: The UNT Digital Library
Detection of coherent structures in the edge of the TEXT tokamak plasma (open access)

Detection of coherent structures in the edge of the TEXT tokamak plasma

This paper discusses detection of coherent structures in the edge of the text tokamak plasma. (LSP)
Date: April 26, 1991
Creator: Filippas, A. V.; Ritz, Ch. P.; Koniges, A. E.; Crotinger, J. A. & Diamond, P. H.
System: The UNT Digital Library
Surface species formed by the adsorption and dissociation of water molecules on Ru(0001) surface containing a small coverage of carbon atoms studied by scanning tunneling microscopy (open access)

Surface species formed by the adsorption and dissociation of water molecules on Ru(0001) surface containing a small coverage of carbon atoms studied by scanning tunneling microscopy

The adsorption and dissociation of water on a Ru(0001) surface containing a small amount ({le} 3 %) of carbon impurities was studied by scanning tunneling microscopy (STM). Various surface species are formed depending on the temperature. These include molecular H{sub 2}O, H{sub 2}O-C complexes, H, O, OH and CH. Clusters of either pure H{sub 2}O or mixed H{sub 2}O-OH species are also formed. Each of these species produces a characteristic contrast in the STM images and can be identified by experiment and by ab initio total energy calculations coupled with STM image simulations. Manipulation of individual species via excitation of vibrational modes with the tunneling electrons has been used as supporting evidence.
Date: April 26, 2008
Creator: UCB, Dept of Materials Science and Engineering
System: The UNT Digital Library
Cobra-IE Evaluation by Simulation of the NUPEC BWR Full-Size Fine-Mesh Bundle Test (BFBT) (open access)

Cobra-IE Evaluation by Simulation of the NUPEC BWR Full-Size Fine-Mesh Bundle Test (BFBT)

The COBRA-IE computer code is a thermal-hydraulic subchannel analysis program capable of simulating phenomena present in both PWRs and BWRs. As part of ongoing COBRA-IE assessment efforts, the code has been evaluated against experimental data from the NUPEC BWR Full-Size Fine-Mesh Bundle Tests (BFBT). The BFBT experiments utilized an 8 x 8 rod bundle to simulate BWR operating conditions and power profiles, providing an excellent database for investigation of the capabilities of the code. Benchmarks performed included steady-state and transient void distribution, single-phase and two-phase pressure drop, and steady-state and transient critical power measurements. COBRA-IE effectively captured the trends seen in the experimental data with acceptable prediction error. Future sensitivity studies are planned to investigate the effects of enabling and/or modifying optional code models dealing with void drift, turbulent mixing, rewetting, and CHF.
Date: April 26, 2006
Creator: Burns, C. J. and Aumiler, D. L.
System: The UNT Digital Library
Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate (open access)

Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate

New high-performance ferroelectric materials based on Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} (PZT) that are doped with cryolite-type strontium niobate (SNO, Sr{sub 4}(Sr{sub 2-2y/3}Nb{sub 2+2y/3})O{sub 11+y}V{sub 0,1-y} with 0 {le} y {le} 1), hence denoted PZT:SNO, and their microscopic structure are described. The combination of exceptional piezoelectric properties, i.e. a piezoelectric strain constant of d{sub 33} {approx} 760 pm/V, with excellent stability and degradation resistance makes ferroelectric PZT:SNO solid solutions very attractive for use in novel and innovative piezoelectric actuator and transducer applications. Extended X-ray absorption fine-structure (EXAFS) analyses of PZT:SNO samples revealed that {approx}10 % of the Sr cations occupy the nominal B-sites of the perovskite-type PZT host lattice. This result was supported by EXAFS analyses of both a canonical SrTiO{sub 3} perovskite and two SNO model and reference compounds. Fit models that do not account for Sr cations on B-sites were ruled out. A clear Sr-Pb peak in Fourier transformed EXAFS data visually confirmed this structural model. The generation of temporary oxygen vacancies and the intricate defect chemistry induced by SNO-doping of PZT are crucial for the exceptional materials properties exhibited by PZT:SNO materials.
Date: April 26, 2007
Creator: Feltz, A.; Schmidt-Winkel, P.; Schossman, M.; Booth, C.H. & Albering, J.
System: The UNT Digital Library
Visualization of Force Fields in Protein StructurePrediction (open access)

Visualization of Force Fields in Protein StructurePrediction

The force fields used in molecular computational biology are not mathematically defined in such a way that their mathematical representation would facilitate the straightforward application of volume visualization techniques. To visualize energy, it is necessary to define a spatial mapping for these fields. Equipped with such a mapping, we can generate volume renderings of the internal energy states in a molecule. We describe our force field, the spatial mapping that we used for energy, and the visualizations that we produced from this mapping. We provide images and animations that offer insight into the computational behavior of the energy optimization algorithms that we employ.
Date: April 26, 2005
Creator: Crawford, Clark; Kreylos, Oliver; Hamann, Bernd & Crivelli, Silvia
System: The UNT Digital Library
Review and interpretation of recent cosmic ray beryllium isotope measurements (open access)

Review and interpretation of recent cosmic ray beryllium isotope measurements

Be/sup 10/ has long been of interest for cosmic ray propagation, because its radioactive decay half-life is well matched to the expected cosmic ray age. Recent beryllium isotope measurements from satellites and balloons have covered an energy range from about 30 to 300 MeV/nucleon/sup 1-3/. At the lowest energies, most of the Be/sup 10/ is absent, indicating a cosmic ray lifetime of order 2 x 10/sup 7/ years and the rather low average density of 0.2 atoms/cc traversed by the cosmic rays. At higher energies, a greater proportion of Be/sup 10/ is observed, indicating a somewhat shorter lifetime. These experiments will be reviewed and then compared with a new experiment covering from 100 to 1000 Mev/nucleon/sup 4/. Although improved experiments will be necessary to realize the full potential of cosmic ray beryllium isotope measurements, these first results are already disclosing interesting and unexpected facts about cosmic ray acceleration and propagation.
Date: April 26, 1978
Creator: Buffington, A.
System: The UNT Digital Library
Manganin stress gages in reacting high explosive environment (5. Experimental methods and techniques). [PBX-9404 and TATB] (open access)

Manganin stress gages in reacting high explosive environment (5. Experimental methods and techniques). [PBX-9404 and TATB]

Manganin stress gages have been fabricated and used successfully to study initiation and detonation of high explosives. These four-terminal, low-impedance gages have been specially designed and encapsulated to minimize the effects of various gage failure mechanisms. Several candidate dielectric encapsulation materials have been tested in the reactive environment, and of these polytetrafluoroethylene has been chosen. Gage stations are formed by thermally bonding the manganin foil between layers of this dielectric. Gages manufactured in this way have been used to provide stress profiles throughout the region of build-up to detonation in PBX-9404 and TATB.
Date: April 26, 1978
Creator: Weingart, R.; Barlett, R.; Cochran, S.; Erickson, L.; Chan, J.; Janzen, J. et al.
System: The UNT Digital Library
A freon-filled, holographic bubble chamber as a high energy photon burst spectrometer (open access)

A freon-filled, holographic bubble chamber as a high energy photon burst spectrometer

A small holographic, freon-filled bubble chamber is being built to measure the energy spectrum of high-energy photons (energy above a few 100 keV) emitted in a short burst (less than about 1 ms duration). The photon energy is calculated from the scattered electron`s energy and direction in the case of Compton scattering or from the electron and positron energies in the case of pair production. Electron and positron energies are determined from the curvature of the tracks in a magnetic field. The use of freon results in a large photon interaction probability. Holography combines good spatial resolution with large depth of field. The main concern for the holographic system is the minimization of the bubble image size, so as to maximize the number of bubbles visible in one hologram. A high energy photon burst spectrometer has several potential applications in Inertial Confinement Fusion research.
Date: April 26, 1994
Creator: Dendooven, P. G. & Lerche, R. A.
System: The UNT Digital Library
Automated binding of attributes to telemetry data (open access)

Automated binding of attributes to telemetry data

An automated method is described for binding attributes to extracted data from a telemetry steam. These attributes can be used by post processing utilities to facilitate efficient analysis. A practical implementation of such a scheme is described.
Date: April 26, 1993
Creator: Kalibjian, J. R.; Voss, T. J.; Yio, J. J. & Hedeline, B.
System: The UNT Digital Library
Accelerator-based atomic physics experiments with photon and ion beams (open access)

Accelerator-based atomic physics experiments with photon and ion beams

Accelerator-based atomic physics experiments at Brookhaven presently use heavy-ion beams from the Dual MP Tandem Van de Graaff Accelerator Facility for atomic physics experiments of several types. Work is presently in progress to develop experiments which will use the intense photon beams which will be available in the near future from the ultraviolet (uv) and x-ray rings of the National Synchrotron Light Source (NSLS). Plans are described for experiments at the NSLS and an exciting development in instrumentation for heavy-ion experiments is summarized.
Date: April 26, 1984
Creator: Johnson, B. M.; Jones, K. W. & Meron, M.
System: The UNT Digital Library
Development of LLNL Methodology for Nonnuclear Safety Bases (open access)

Development of LLNL Methodology for Nonnuclear Safety Bases

The objective of this paper is to introduce the process and philosophies used to develop LLNL methodology for performing nonnuclear safety bases. Our former approach needed revision in order to implement the new Work Smart Standard (WSS), 'Safety Basis Requirements for Nonnuclear Facilities at Lawrence Livermore National Laboratory Site Specific Standard' (UCRL-ID-150214), approved in 2003 and revised January, 2004. This work relates directly to the following workshop theme: 'Improvements in Chemical, Biological, and Non-nuclear Safety analysis.' A requirements document, Environmental Safety and Health Manual, Document 3.1 provides safety bases methodology 'how-to' for LLNL personnel. This methodology document had to undergo a major revision, and essentially was completely re-written, since the nonnuclear requirements underwent a major change due to the new standard. The new methodology was based on a graded approach respective to risk level for each hazard type and facility classification. The development process included input from a cross-section of representatives of LLNL organizations at every step in the process. The initial methodology was tested in a pilot project that resulted in completed safety basis analyses and documentation for a major facility at LLNL. Feedback from the pilot was used to refine the methodology. The new methodology promotes a graded …
Date: April 26, 2004
Creator: van Warmerdam, C M & Pinkston, D M
System: The UNT Digital Library
General Relativistic Magnetohydrodynamic Simulations of Magnetically Choked Accretion Flows around Black Holes (open access)

General Relativistic Magnetohydrodynamic Simulations of Magnetically Choked Accretion Flows around Black Holes

Black hole (BH) accretion flows and jets are qualitatively affected by the presence of ordered magnetic fields. We study fully three-dimensional global general relativistic magnetohydrodynamic (MHD) simulations of radially extended and thick (height H to cylindrical radius R ratio of |H/R| {approx} 0.2-1) accretion flows around BHs with various dimensionless spins (a/M, with BH mass M) and with initially toroidally-dominated ({phi}-directed) and poloidally-dominated (R-z directed) magnetic fields. Firstly, for toroidal field models and BHs with high enough |a/M|, coherent large-scale (i.e. >> H) dipolar poloidal magnetic flux patches emerge, thread the BH, and generate transient relativistic jets. Secondly, for poloidal field models, poloidal magnetic flux readily accretes through the disk from large radii and builds-up to a natural saturation point near the BH. While models with |H/R| {approx} 1 and |a/M| {le} 0.5 do not launch jets due to quenching by mass infall, for sufficiently high |a/M| or low |H/R| the polar magnetic field compresses the inflow into a geometrically thin highly non-axisymmetric 'magnetically choked accretion flow' (MCAF) within which the standard linear magneto-rotational instability is suppressed. The condition of a highly-magnetized state over most of the horizon is optimal for the Blandford-Znajek mechanism that generates persistent relativistic jets with …
Date: April 26, 2012
Creator: McKinney, Jonathan C.; Tchekhovskoy, Alexander & Blandford, Roger D.
System: The UNT Digital Library
Acoustic emission experiments for safety of nuclear reactor vessels (open access)

Acoustic emission experiments for safety of nuclear reactor vessels

Acoustic emission monitoring was used in hydrostatic experiments on flawed pressure vessels and thermal shock experiments on flawed cylindrical specimens. The results of the experiments are discussed.
Date: April 26, 1976
Creator: Ying, S. P.
System: The UNT Digital Library
Biospecimen Reporting for Improved Study Quality (BRISQ) (open access)

Biospecimen Reporting for Improved Study Quality (BRISQ)

Human biospecimens are subject to a number of different collection, processing, and storage factors that can significantly alter their molecular composition and consistency. These biospecimen preanalytical factors, in turn, influence experimental outcomes and the ability to reproduce scientific results. Currently, the extent and type of information specific to the biospecimen preanalytical conditions reported in scientific publications and regulatory submissions varies widely. To improve the quality of research utilizing human tissues it is critical that information regarding the handling of biospecimens be reported in a thorough, accurate, and standardized manner. The Biospecimen Reporting for Improved Study Quality (BRISQ) recommendations outlined herein are intended to apply to any study in which human biospecimens are used. The purpose of reporting these details is to supply others, from researchers to regulators, with more consistent and standardized information to better evaluate, interpret, compare, and reproduce the experimental results. The BRISQ guidelines are proposed as an important and timely resource tool to strengthen communication and publications around biospecimen-related research and help reassure patient contributors and the advocacy community that the contributions are valued and respected.
Date: April 26, 2011
Creator: Moore, Ph.D., Helen M.; Kelly Ph.D., Andrea; Jewell Ph.D., Scott D.; McShane Ph.D., Lisa M.; Clark M.D., Douglas P.; Greenspan M.D., Renata et al.
System: The UNT Digital Library
Beyond Mean-Field Calculation For Pairing Correlation (open access)

Beyond Mean-Field Calculation For Pairing Correlation

None
Date: April 26, 2012
Creator: Hupin, G & Lacroix, D
System: The UNT Digital Library
A New Limit on Time-Reversal Violation in Beta Decay (open access)

A New Limit on Time-Reversal Violation in Beta Decay

We report the results of an improved determination of the triple correlation DP {center_dot} (p{sub e} x p{sub v}) that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the Standard Model. Our result is D = (-0.96 {+-} 1.89(stat) {+-} 1.01(sys)) x 10{sup -4}. The corresponding phase between g{sub A} and g{sub V} is {phi}{sub AV} = 180.013{sup o} {+-} 0.028{sup o} (68% confidence level). This result represents the most sensitive measurement of D in nuclear beta decay.
Date: April 26, 2011
Creator: Mumm, H P; Chupp, T E; Cooper, R L; Coulter, K P; Freedman, S J; Fujikawa, B K et al.
System: The UNT Digital Library
Measurement of electron-hole friction in an n-doped GaAs/AlGaAs quantum well using optical transient-grating spectroscopy (open access)

Measurement of electron-hole friction in an n-doped GaAs/AlGaAs quantum well using optical transient-grating spectroscopy

We use phase-resolved transient grating spectroscopy to measure the drift and diffusion of electron-hole density waves in a semiconductor quantum well. The unique aspects of this optical probe allow us to determine the frictional force between a two-dimensional Fermi liquid of electrons and a dilute gas of holes. Knowledge of electron-hole friction enables prediction of ambipolar dynamics in high-mobility electron systems.
Date: April 26, 2011
Creator: Yang, Luyi; Koralek, J. D.; Orenstein, J.; Tibbetts, D. R.; Reno, J. L. & Lilly, M. P.
System: The UNT Digital Library
Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions (open access)

Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions

We report on the experiments aimed at obtaining core temperature and density maps in direct drive implosions at the OMEGA Laser Facility using multi-monochromatic X-ray imagers. These instruments use an array of pinholes and a flat multilayer mirror to provide unique multi-spectral images distributed over a wide spectral range. Using Argon as a dopant in the DD-filled plastic shells produces emission images in the Ar He-b and Ly-b spectral regions. These images allow the retrieval of temperature and density maps of the plasma. We deployed three identical multi-monochromatic X-ray imagers in a quasi-orthogonal line-of-sight configuration to allow tomographic reconstruction of the structure of the imploding core.
Date: April 26, 2006
Creator: Tommasini, R; Koch, J A; Izumi, N; Welser, L A; Mancini, R C; Delettrez, J et al.
System: The UNT Digital Library
Biogeophysical effects of CO2-fertilization on global climate (open access)

Biogeophysical effects of CO2-fertilization on global climate

CO{sub 2}-fertilization affects plant growth, which modifies surface physical properties, altering the surface albedo, and fluxes of sensible and latent heat. We investigate how such CO{sub 2}-fertilization effects on vegetation and surface properties would affect the climate system. Using a global three-dimensional climate-carbon model that simulates vegetation dynamics, we compare two multi-century simulations: a ''Control'' simulation with no emissions, and a ''Physiol-noGHG'' simulation where physiological changes occur as a result of prescribed CO{sub 2} emissions, but where CO{sub 2}-induced greenhouse warming is not included. In our simulations, CO{sub 2}-fertilization produces warming; we obtain an annual- and global-mean warming of about 0.65 K (and land-only warming of 1.4 K) after 430 years. This century-scale warming is mostly due to a decreased surface albedo associated with the expansion of the Northern Hemisphere boreal forests. On decadal time scales, the CO{sub 2} uptake by afforestation should produce a cooling effect that exceeds this albedo-based warming; but if the forests remain in place, the CO{sub 2}-enhanced-greenhouse effect would diminish as the ocean equilibrates with the atmosphere, whereas the albedo effect would persist. Thus, on century time scales, there is the prospect for net warming from CO{sub 2}-fertilization of the land biosphere. Further study is …
Date: April 26, 2006
Creator: Bala, G.; Caldeira, K.; Mirin, A.; Wickett, M.; Delire, C. & Phillips, T. J.
System: The UNT Digital Library
Axisymmetric Tandem Mirror Magnetic Fusion Energy Power Plant with Thick Liquid-Walls (open access)

Axisymmetric Tandem Mirror Magnetic Fusion Energy Power Plant with Thick Liquid-Walls

A fusion power plant is described that utilizes a new version of the tandem mirror device including spinning liquid walls. The magnetic configuration is evaluated with an axisymmetric equilibrium code predicting an average beta of 60%. The geometry allows a flowing molten salt, (flibe-Li{sub 2}BeF{sub 4}), which protects the walls and structures from damage arising from neutrons and plasma particles. The free surface between the liquid and the burning plasma is heated by bremsstrahlung radiation, line radiation, and by neutrons. The temperature of the free surface of the liquid is calculated, and then the evaporation rate is estimated from vapor-pressure data. The allowed impurity concentration in the burning plasma is taken as 1% fluorine, which gives a 17% reduction in the fusion power owing to D/T fuel dilution, with F line-radiation causing minor power degradation. The end leakage power density of 0.6 MW/m{sup 2} is readily handled by liquid jets. The tritium breeding is adequate with natural lithium. A number of problem areas are identified that need further study to make the design more self-consistent and workable; however, the simple geometry and the use of liquid walls promise the cost of power competitive with that from fission and coal.
Date: April 26, 2006
Creator: Moir, R W & Rognlien, T D
System: The UNT Digital Library
TIME RESOLVED X-RAY SPOT DIAGNOSTIC (open access)

TIME RESOLVED X-RAY SPOT DIAGNOSTIC

A diagnostic was developed for the determination of temporal history of an X-ray spot. A pair of thin (0.5 mm) slits image the x-ray spot to a fast scintillator which is coupled to a fast detector, thus sampling a slice of the X-Ray spot. Two other scintillator/detectors are used to determine the position of the spot and total forward dose. The slit signal is normalized to the dose and the resulting signal is analyzed to get the spot size. The position information is used to compensate for small changes due to spot motion and misalignment. The time resolution of the diagnostic is about 1 ns and measures spots from 0.5 mm to over 3 mm. The theory and equations used to calculate spot size and position are presented, as well as data. The calculations assume a symmetric, Gaussian spot. The spot data is generated by the ETA II accelerator, a 2kA, 5.5 MeV, 60 ns electron beam focused on a Tantalum target. The spot generated is typically about 1 mm FWHM. Comparisons are made to an X-ray pinhole camera which images the X-Ray spot (in 2D) at four time slices.
Date: April 26, 2005
Creator: Richardson, R.; Guethlein, G.; Falabella, S.; Chambers, F.; Raymond, B. & Weir, J.
System: The UNT Digital Library
The March 11, 2002 Masafi, United Arab Emirates Earthquake: Insights into the Seismotectonics of the Northern Oman Mountains (open access)

The March 11, 2002 Masafi, United Arab Emirates Earthquake: Insights into the Seismotectonics of the Northern Oman Mountains

A moderate (M{approx}5) earthquake struck the northeastern United Arab Emirates (UAE) and northern Oman on March 11, 2002. The event was felt over a wide area of the northern Emirates and was accompanied by smaller (felt) events before and after the March 11 main shock. The event was large enough to be detected and located by global networks at teleseismic distances. We estimated focal mechanism and depth from broadband complete regional waveform modeling. We report a normal mechanism with a slight right-lateral strike-slip component consistent with the large-scale tectonics. The normal component suggests relaxation of obducted crust of the Semail Ophilite (specifically, the Khor Fakkan Block) while the right-lateral strike-slip component of the mechanism is consistent with shear across the Oman Line. Felt earthquakes are rare in the region, however no regional seismic network exists in the UAE to determine local seismicity. This event offers a unique opportunity to study the active tectonics of the region as well as inform future studies of seismic hazard in the UAE and northern Oman.
Date: April 26, 2005
Creator: Rodgers, A.; Fowler, A.; Al-Amri, A. & Al-Enezi, A.
System: The UNT Digital Library