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3-D Hydrodynamic Modeling in a Geospatial Framework (open access)

3-D Hydrodynamic Modeling in a Geospatial Framework

3-D hydrodynamic models are used by the Savannah River National Laboratory (SRNL) to simulate the transport of thermal and radionuclide discharges in coastal estuary systems. Development of such models requires accurate bathymetry, coastline, and boundary condition data in conjunction with the ability to rapidly discretize model domains and interpolate the required geospatial data onto the domain. To facilitate rapid and accurate hydrodynamic model development, SRNL has developed a pre- and post-processor application in a geospatial framework to automate the creation of models using existing data. This automated capability allows development of very detailed models to maximize exploitation of available surface water radionuclide sample data and thermal imagery.
Date: August 24, 2006
Creator: Bollinger, J.; Alfred Garrett, A.; Larry Koffman, L. & David Hayes, D
System: The UNT Digital Library
3w Transmitted Beam Diagnostic at the Omega Laser Facility (open access)

3w Transmitted Beam Diagnostic at the Omega Laser Facility

A 3{omega} transmitted beam diagnostic has been commissioned on the Omega Laser at the Laboratory for Laser Energetics, University of Rochester [Soures et.al., Laser Part. Beams 11 (1993)]. Transmitted light from one beam is collected by a large focusing mirror and directed onto a diagnostic platform. The near field of the transmitted light is imaged; the system collects information from twice the original f-cone of the beam. Two gated optical cameras capture the near field image of the transmitted light. Thirteen spatial positions around the measurement region are temporally resolved using fast photodiodes to allow a measure of the beam spray evolution. The Forward stimulated Raman scattering and forward simulated Brillion scattering are spectrally and temporally resolved at 5 independent locations within twice the original f-cone. The total transmitted energy is measured in two spectral bands ({delta}{lambda} < 400 nm and {delta}{lambda} > 400 nm).
Date: April 24, 2006
Creator: Froula, D. H.; Rekow, V.; Sorce, C.; Piston, K.; Knight, R.; Alvarez, S. et al.
System: The UNT Digital Library
Accelerator Physics Code Web Repository (open access)

Accelerator Physics Code Web Repository

In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this repository, illustrate its usage, and discuss our future plans, with emphasis on code benchmarking.
Date: October 24, 2006
Creator: Zimmermann, F.; Basset, R.; Bellodi, G.; Benedetto, E.; Dorda, U.; Giovannozzi, M. et al.
System: The UNT Digital Library
Anodic Kinetics of NiCriMo Alloys during Localized Corrosion (open access)

Anodic Kinetics of NiCriMo Alloys during Localized Corrosion

This report talks about Anodic Kinetics of NiCriMo Alloys during Localized Corrosion
Date: February 24, 2006
Creator: He, David X. & Newman, Roger C.
System: The UNT Digital Library
Birds of a Feather: Supporting Secure Systems (open access)

Birds of a Feather: Supporting Secure Systems

Over the past few years Lawrence Livermore National Laboratory has begun the process of moving to a diskless environment in the Secure Computer Support realm. This movement has included many moving targets and increasing support complexity. We would like to set up a forum for Security and Support professionals to get together from across the Complex and discuss current deployments, lessons learned, and next steps. This would include what hardware, software, and hard copy based solutions are being used to manage Secure Computing. The topics to be discussed include but are not limited to: Diskless computing, port locking and management, PC, Mac, and Linux/UNIX support and setup, system imaging, security setup documentation and templates, security documentation and management, customer tracking, ticket tracking, software download and management, log management, backup/disaster recovery, and mixed media environments.
Date: April 24, 2006
Creator: Braswell, H. V., III
System: The UNT Digital Library
CHARACTERIZING THE YUCCA MOUNTAIN SITE FOR DEVELOPING SEISMIC DESIGN GROUND MOTIONS (open access)

CHARACTERIZING THE YUCCA MOUNTAIN SITE FOR DEVELOPING SEISMIC DESIGN GROUND MOTIONS

Yucca Mountain, Nevada is the designated site for the first long-term geologic repository to safely dispose spent nuclear fuel and high-level nuclear waste in the U.S. Yucca Mountain consists of stacked layers of welded and non-welded volcanic tuffs. Site characterization studies are being performed to assess its future performance as a permanent geologic repository. These studies include the characterization of the shear-wave velocity (Vs) structure of the repository block and the surface facilities area. The Vs data are an input in the calculations of ground motions for the preclosure seismic design and for postclosure performance assessment and therefore their accurate estimation is needed. Three techniques have been employed: 24 downhole surveys, 15 suspension seismic logging surveys and 95 spectral-analysis-of-surface-waves (SASW) surveys have been performed to date at the site. The three data sets were compared with one another and with Vs profiles developed from vertical seismic profiling data collected by the Lawrence Berkeley National Laboratory and with Vs profiles developed independently by the University of Nevada, Reno using the refraction microtremor technique. Based on these data, base case Vs profiles have been developed and used in site response analyses. Since the question of adequate sampling arises in site characterization programs …
Date: February 24, 2006
Creator: S. Upadhyaya, I. Wong, R. Kulkarni, K. Stokoe, M. Dober, W. Silva, and R. Quittmeyer
System: The UNT Digital Library
Closure of the Fast Flux Test Facility (FFTF) History & Status & Future Plans (open access)

Closure of the Fast Flux Test Facility (FFTF) History & Status & Future Plans

In 1993, the US Department of Energy (DOE) decided to shut down the Fast Flux Test Facility (FFTF) due to lack of national missions that justified the annual operating budget of approximately $88M/year. The initial vision was to ''deactive'' the facility to an industrially and radiologically safe condition to allow long-term, minimal surveillance storage until approximately 2045. This approach would minimize near term cash flow and allow the radioactive decay of activated components. The final decontamination and decommissioning (D and D) would then be performed using then-current methodology in a safe and efficient manner. the philosophy has now changed to close coupling the initial deactivation with final D and D. This paper presents the status of the facility and focuses on the future challenge of sodium removal.
Date: February 24, 2006
Creator: Farabee, O. A.
System: The UNT Digital Library
COMPARISON OF NATURAL BACKGROUND DOSE RATES FOR RESIDENTS OF THE AMARGOSA VALLEY, NV, TO THOSE IN LEADVILLE, CO, AND THE STATES OF COLORADO AND NEVADA (open access)

COMPARISON OF NATURAL BACKGROUND DOSE RATES FOR RESIDENTS OF THE AMARGOSA VALLEY, NV, TO THOSE IN LEADVILLE, CO, AND THE STATES OF COLORADO AND NEVADA

In the latter half of 2005, the U.S. Environmental Protection Agency (USEPA) published a Proposed Rule (40 CFR Part 197) for establishing a dose rate standard for limiting radionuclide releases from the proposed Yucca Mountain high-level radioactive waste repository during the time period from 10{sup 4} to 10{sup 6} years after closure. The proposed standard was based on the difference in the estimated total dose rate from natural background in the Amargosa Valley and the ''average annual background radiation'' for the State of Colorado. As defined by the USEPA, ''natural background radiation consists of external exposures from cosmic and terrestrial sources, and internal exposures from indoor exposures to naturally-occurring radon''. On the basis of its assessments, the USEPA estimated that the difference in the dose rate in the two identified areas was 3.5 mSv y{sup -1}. The purpose of this review was to provide an independent evaluation and review of this estimate. One of the first observations was that, because site-specific dose rate measurements for the Amargosa Valley ''were not available'', the dose rates for various sources of natural background in that area, used by the USEPA in its assessment, were based on modifications of the average values for the …
Date: February 24, 2006
Creator: Sun, D. Moeller and L. C.
System: The UNT Digital Library
Comparison of the Acceptability of Various Oil Shale Processes (open access)

Comparison of the Acceptability of Various Oil Shale Processes

None
Date: November 24, 2006
Creator: Burnham, A K & McConaghy, J R
System: The UNT Digital Library
Coulomb Excitation of the 242mAm Isomer (open access)

Coulomb Excitation of the 242mAm Isomer

The {sup 242m}Am isomer, a well-known candidate for photo-depopulation research, has been studied in this first ever Coulomb excitation of a nearly pure ({approx} 98%) isomer target. Thirty new states, including a new rotational band built on a K{sup {pi}} = 6{sup -} state have been identified. Strong K-mixing results in nearly equal populations of the K{sup {pi}} = 5{sup -} and 6{sup -} states. Newly identified states have been assigned to the K{sup {pi}} = 3{sup -} rotational band, the lowest states of which are known to decay into the ground-state band. Implications regarding K-mixing and Coulomb excitation paths to the ground state are discussed.
Date: October 24, 2006
Creator: Hayes, A. B.; Cline, D.; Moody, K. J.; Wu, C. Y.; Becker, J. A.; Carpenter, M. P. et al.
System: The UNT Digital Library
T. D. Lee: Relativistic Heavy Ion Collisions and the Riken Brookhaven Center. (open access)

T. D. Lee: Relativistic Heavy Ion Collisions and the Riken Brookhaven Center.

This paper presents the history of Professor T. D. Lee's seminal work on the theory of relativistic heavy ion collisions, and the founding and development of the Riken Brookhaven Center. A number of anecdotes are given about Prof. Lee, and his strong positive effect on his colleagues, particularly young physicists.
Date: November 24, 2006
Creator: McLerran, L. & Samios, N.
System: The UNT Digital Library
Development of Alternative Glass Formulations for Vitrification of Excess Plutonium - SEM/XRD Analyses (open access)

Development of Alternative Glass Formulations for Vitrification of Excess Plutonium - SEM/XRD Analyses

None
Date: April 24, 2006
Creator: Crawford, Charles L.; Marra, J. C.; Peeler, D. K. & Bibler, N. E.
System: The UNT Digital Library
Discovery of a z = 6.1 Radio-Loud Quasar in the NDWFS (open access)

Discovery of a z = 6.1 Radio-Loud Quasar in the NDWFS

From examination of only 4 deg{sup 2} of sky in the NOAO Deep Wide-Field Survey (NDWFS) region, we have identified the first radio-loud quasar at a redshift z > 6. The object, FIRST J1427385+331241, was discovered by matching the FLAMEX IR survey to FIRST survey radio sources with NDWFS counterparts. One candidate z > 6 quasar was found, and spectroscopy with the Keck II telescope confirmed its identification, yielding a redshift z = 6.12. The object is a Broad Absorption Line (BAL) quasar with an optical luminosity of M{sub B} {approx} -26.9 and a radio-to-optical flux ratio {approx} 60. Two Mg II absorptions systems are present at redshifts of z = 2.18 and z = 2.20. We briefly discuss the implications of this discovery for the high-redshift quasar population.
Date: July 24, 2006
Creator: McGreer, I D; Becker, R H; Helfand, D J & White, R L
System: The UNT Digital Library
Elevated Uptake of Th and U by Netted Chain Fern (Woodwardia areloata) (open access)

Elevated Uptake of Th and U by Netted Chain Fern (Woodwardia areloata)

None
Date: March 24, 2006
Creator: KNOX, ANNA
System: The UNT Digital Library
Emittance Limitation of a Conditioned Beam in a Strong Focusing FEL Undulator (open access)

Emittance Limitation of a Conditioned Beam in a Strong Focusing FEL Undulator

Various methods have been proposed to condition an electron beam in order to reduce its emittance effect and to improve the short-wavelength free electron laser (FEL) performance. In this paper, we show that beam conditioning does not result in a complete elimination of the emittance effect in an alternating-gradient focusing FEL undulator. Using a one-dimensional model and a three-dimensional simulation code, we derive a criteria for the emittance limitation of a perfectly conditioned beam that depends on the focusing structure.
Date: March 24, 2006
Creator: Huang, Z.; Stupakov, G. & Reiche, S.
System: The UNT Digital Library
Encouraging PV Adoption in New Market-Rate ResidentialConstruction: A Critical Review of Program Experiences to Date (open access)

Encouraging PV Adoption in New Market-Rate ResidentialConstruction: A Critical Review of Program Experiences to Date

In this paper, we review experiences with programs to support the deployment of photovoltaics (PV) in new, market-rate homes, drawing upon interviews with program managers around the country, project data, and publicly-available documentation on program design, impacts, and experiences. We focus on state clean energy funds, which have been established in 14 U.S. states to build markets for clean energy resources, as well as a select number of other state or local organizations whose activities are particularly noteworthy. We describe the types of programs implemented and their impacts to date, and discuss key issues and lessons learned for initiatives aimed at growing the new home market for PV.
Date: April 24, 2006
Creator: Barbose, Galen; Wiser, Ryan & Bolinger, Mark
System: The UNT Digital Library
Enhanced Energetic Stability and Optical Activity of Symmetry-Reduced C60 (open access)

Enhanced Energetic Stability and Optical Activity of Symmetry-Reduced C60

Since its discovery in 1985, the celebrated geodesic cage structure of the C{sub 60} molecule has been recognized: a truncated icosahedron in which all sixty vertices are equivalent and has the full I{sub h} symmetry, making it thus far the most spherical of all known molecules. Inherent in this high symmetry is an intricate network of electron-phonon coupling, evident in phonon progressions and vibronic peak broadening, and resulting in structural distortions of neutral C{sub 60} in the presence of solvent. Within the I{sub h} symmetry group of this molecule, of the forty-six distinct vibrational frequencies only ten are Raman-active and four are IR-active (in the first order), while the remaining 32 modes are optically silent. Symmetry-reduced structures of C{sub 60} would activate some of these silent modes, which could then be amenable to experimental verification such as in resonance Raman scattering. Here, quantum chemical calculations within density functional theory establish for the first times (1) lower-symmetry, energetically more stable structures for C{sub 60}, the lowest of which is of D{sub 3d} symmetry, and with a new assignment of the ground state as the {sup 1}A{sub 1g} state, (2) the activation of some IR and Raman I{sub h} silent modes: the …
Date: January 24, 2006
Creator: Manaa, M R
System: The UNT Digital Library
Environmental Degradation of Materials for Nuclear Waste Repositories Engineered Barriers (open access)

Environmental Degradation of Materials for Nuclear Waste Repositories Engineered Barriers

Several countries are considering geological repositories for the storage of nuclear waste. Most of the environments for these repositories will be reducing in nature, except for the repository in the US, which is going to be oxidizing. For the reducing repositories, alloys such as carbon steel, copper, stainless steels and titanium are being evaluated. For the repository in the US, some of the most corrosion resistant commercially available alloys are being investigated. This paper presents a summary of the behavior of the different materials under consideration for the repositories and the current understanding of the degradation modes of the proposed alloys in ground water environments from the point of view of general corrosion, localized corrosion and environmentally assisted cracking.
Date: December 24, 2006
Creator: Rebak, R B
System: The UNT Digital Library
EUV testing of multilayer mirrors: critical issues (open access)

EUV testing of multilayer mirrors: critical issues

Recently, while performing extensive EUV irradiation endurance testing on Ru-capped multilayer mirrors in the presence of elevated partial pressures of water and hydrocarbons, NIST has observed that the amount of EUV-induced damage actually decreases with increasing levels of water vapor above {approx} 5 x 10{sup -7} Torr. It is thought that the admitted water vapor may interact with otherwise stable, condensed carbonaceous species in an UHV vacuum system to increase the background levels of simple gaseous carbon-containing molecules. Some support for this hypothesis was demonstrated by observing the mitigating effect of very small levels of simple hydrocarbons with the intentional introduction of methyl alcohol in addition to the water vapor. It was found that the damage rate decreased by at least an order of magnitude when the partial pressure of methyl alcohol was just one percent of the water partial pressure. These observations indicate that the hydrocarbon components of the vacuum environment under actual testing conditions must be characterized and controlled to 10{sup -11} Torr or better in order to quantify the damage caused by high levels of water vapor. The possible effects of exposure beam size and out-of-band radiation on mirror lifetime testing will also be discussed.
Date: February 24, 2006
Creator: Hill, S B; Ermanoski, I; Grantham, S; Tarrio, C; Lucatorto, T B; Madey, T E et al.
System: The UNT Digital Library
Experiment and theory in interplay on high-Z few-electron ion spectra from foil-excited ion beams and electron beam ion traps (open access)

Experiment and theory in interplay on high-Z few-electron ion spectra from foil-excited ion beams and electron beam ion traps

None
Date: July 24, 2006
Creator: Trabert, E; Beiersdorfer, P; Pinnington, E H; Utter, S B; Vilkas, M J & Ishikawa, Y
System: The UNT Digital Library
Experimental characterization of initial conditions and spatio-temporal evolution of a small Atwood number Rayleigh-Taylor mixing layer (open access)

Experimental characterization of initial conditions and spatio-temporal evolution of a small Atwood number Rayleigh-Taylor mixing layer

The initial multi-mode interfacial velocity and density perturbations present at the onset of a small Atwood number, incompressible, miscible, Rayleigh-Taylor instability-driven mixing layer have been quantified using a combination of experimental techniques. The streamwise interfacial and spanwise interfacial perturbations were measured using high-resolution thermocouples and planar laser-induced fluorescence (PLIF), respectively. The initial multi-mode streamwise velocity perturbations at the two-fluid density interface were measured using particle-image velocimetry (PIV). It was found that the measured initial conditions describe an initially anisotropic state, in which the perturbations in the streamwise and spanwise directions are independent of one another. The evolution of various fluctuating velocity and density statistics, together with velocity and density variance spectra, were measured using PIV and high-resolution thermocouple data. The evolution of the velocity and density statistics is used to investigate the early-time evolution and the onset of strongly-nonlinear, transitional dynamics within the mixing layer. The early-time evolution of the density and vertical velocity variance spectra indicate that velocity fluctuations are the dominant mechanism driving the instability development. The implications of the present experimental measurements on the initialization of Reynolds-averaged turbulent transport and mixing models and of direct and large-eddy simulations of Rayleigh-Taylor instability-induced turbulence are discussed.
Date: March 24, 2006
Creator: Mueschke, N J; Andrews, M J & Schilling, O
System: The UNT Digital Library
Extending the cereus group genomics to putative food-borne pathogens of different toxicity (open access)

Extending the cereus group genomics to putative food-borne pathogens of different toxicity

The cereus group represents sporulating soil bacteriacontaining pathogenic strains which may cause diarrheic or emetic foodpoisoning outbreaks. Multiple locus sequence typing revealed a presencein natural samples of these bacteria of about thirty clonal complexes.Application of genomic methods to this group was however biased due tothe major interest for representatives closely related to B. anthracis.Albeit the most important food-borne pathogens were not yet defined,existing dataindicate that they are scattered all over the phylogenetictree. The preliminary analysis of the sequences of three genomesdiscussed in this paper narrows down the gaps in our knowledge of thecereus group. The strain NVH391-98 is a rare but particularly severefood-borne pathogen. Sequencing revealed that the strain must be arepresentative of a novel bacterial species, for which the name Bacilluscytotoxis is proposed. This strain has a reduced genome size compared toother cereus group strains. Genome analysis revealed absence of sigma Bfactor and the presence of genes encoding diarrheic Nhe toxin, notdetected earlier. The strain B. cereus F837/76 represents a clonalcomplex close to that of B. anthracis. Including F837/76, three such B.cereus strains had been sequenced. Alignment of genomes suggests that B.anthracis is their common ancestor. Since such strains often emerge fromclinical cases, they merit a special attention. The …
Date: August 24, 2006
Creator: Lapidus, Alla; Goltsman, Eugene; Auger, Sandrine; Galleron, Nathalie; Segurens, Beatrice; Dossat, Carole et al.
System: The UNT Digital Library
The First Estimate of BR(\bar B to X_s\gamma) at O(\alpha_s^2) (open access)

The First Estimate of BR(\bar B to X_s\gamma) at O(\alpha_s^2)

Combining our results for various {Omicron}({alpha}{sub s}{sup 2}) corrections to the weak radiative B-meson decay, we are able to present the first estimate of the branching ratio at the next-to-next-to-leading order in QCD. We find {Beta}({bar B} {yields} X{sub s}{gamma}) = (3.15 {+-} 0.23) x 10{sup -4} for E{sub {gamma}} > 1.6 GeV in the {bar B}-meson rest frame. The four types of uncertainties: non-perturbative (5%), parametric (3%), higher-order (3%) and m{sub c}-interpolation ambiguity (3%) have been added in quadrature to obtain the total error.
Date: October 24, 2006
Creator: Misiak, M.; Asatrian, H. M.; Bieri, K.; Czakon, M.; Czarnecki, A.; Ewerth, T. et al.
System: The UNT Digital Library
The fixed hypernode method for the solution of the many body Schroedinger equation (open access)

The fixed hypernode method for the solution of the many body Schroedinger equation

We propose a new scheme for an approximate solution of the Schroedinger equation for a many-body interacting system, based on the use of pairs of walkers. Trial wavefunctions for these pairs are combinations of standard symmetric and antisymmetric wavefunctions. The method consists in applying a fixed-node restriction in the enlarged space, and computing the energy of the antisymmetric state from the knowledge of the exact ground state energy for the symmetric state. We made two conjectures: first, that this fixed-hypernode energy is an upper bound to the true fermion energy; second that this bound would necessarily be lower than the usual fixed-node energy using the same antisymmetric trial function. The first conjecture is true, and is proved in this paper. The second is not, and numerical and analytical counterexamples are given. The question of whether the fixed-hypernode energy can be better than the usual bound remains open.
Date: January 24, 2006
Creator: Pederiva, F; Kalos, M H; Reboredo, F; Bressanini, D; Guclu, D; Colletti, L et al.
System: The UNT Digital Library