Field Line Resonance at Mercury's Magnetosphere: A Simulation Study (open access)

Field Line Resonance at Mercury's Magnetosphere: A Simulation Study

Ultra low frequency (ULF) waves, which are assumed to be standing waves on the field, are observed by the Mariner 10 spacecraft at Mercury. These waves are oscillating at 38% of the proton gyrofrequency. It is well known that the heavy ions, such as Na+, are abundant in Mercury's magnetosphere. Because the presence of different ion species has an influence on the plasma dispersion characteristics near the ion gyro-frequencies, such relatively high frequencies of magnetospheric eigenoscillations at Mercury require a multi-fluid treatment for the plasma. Thus ULF waves at Mercury may have a distinct difference from typical ULF oscillations at Earth, which are often described in terms of magnetohydrodynamics (MHD). By adopting a multi-fluid numerical wave model, we examine how magnetic eigenoscillations occur in Mercury's magnetosphere. Because protons and sodium ions are the main constituents at Mercury, we assume an electron-proton- sodium plasma in our model. The frequency spectra and time histories of the electromagnetic fields at the ion-ion hybrid (IIH) and cavity resonances are presented. Our results show: (1) The observed ULF waves are likely compressional waves rather than FLR. (2) Resonant absorption occurs at the IIH resonance, thus incoming compressional waves are converted into the IIH resonance. (3) …
Date: May 22, 2008
Creator: Eun-Hwa Kim, Jay R. Johnson, and Dong-Hun Lee
Object Type: Report
System: The UNT Digital Library
Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source (open access)

Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source

Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power …
Date: May 22, 2009
Creator: Lacy, Jeffrey L
Object Type: Report
System: The UNT Digital Library
RIA Superconducting Drift Tube Linac R & D (open access)

RIA Superconducting Drift Tube Linac R & D

Cavity and cryomodule development work for a superconducting ion linac has been underway for several years at the National Superconducting Cyclotron Laboratory. The original application of the work was the proposed Rare Isotope Accelerator. At present, the work is being continued for use with the Facility for Rare Isotope Beams (FRIB). The baseline linac for FRIB requires 4 types of superconducting cavities to cover the velocity range needed to accelerate an ion beam to #21; 200 MeV/u: 2 types of quarter-wave resonator (QWR) and 2 types of half-wave resonator (HWR). Superconducting solenoids are used for focussing. Active and passive shielding is required to ensure that the solenoids’ field does not degrade the cavity performance. First prototypes of both QWR types and one HWR type have been fabricated and tested. A prototype solenoid has been procured and tested. A test cryomodule has been fabricated and tested. The test cryomodule contains one QWR, one HWR, one solenoid, and one super-ferric quadrupole. This report covers the design, fabrication, and testing of this cryomodule
Date: May 22, 2009
Creator: Popielarski, J.; Bierwagen, J.; Bricker, S.; Compton, C.; DeLauter, J.; Glennon, P. et al.
Object Type: Report
System: The UNT Digital Library
Atmospheric Radiation Measurement program climate research facility operations quarterly report January 1 - March 31, 2008. (open access)

Atmospheric Radiation Measurement program climate research facility operations quarterly report January 1 - March 31, 2008.

Individual raw data streams from instrumentation at the Atmospheric Radiation Measurement (ARM) Program Climate Research Facility (ACRF) fixed and mobile sites are collected and sent to the Data Management Facility (DMF) at Pacific Northwest National Laboratory (PNNL) for processing in near real time. Raw and processed data are then sent daily to the ACRF Archive, where they are made available to users. For each instrument, we calculate the ratio of the actual number of data records received daily at the Archive to the expected number of data records. The results are tabulated by (1) individual data stream, site, and month for the current year and (2) site and fiscal year (FY) dating back to 1998. Table 1 shows the accumulated maximum operation time (planned uptime), actual hours of operation, and variance (unplanned downtime) for the period January 1 - March 31, 2008, for the fixed sites. The AMF is being deployed to China and is not in operation this quarter. The second quarter comprises a total of 2,184 hours. The average as well as the individual site values exceeded our goal this quarter. The Site Access Request System is a web-based database used to track visitors to the fixed and …
Date: May 22, 2008
Creator: Sisterson, D. L.
Object Type: Report
System: The UNT Digital Library
Fast spot-based multiscale simulations of granular drainage (open access)

Fast spot-based multiscale simulations of granular drainage

We develop a multiscale simulation method for dense granular drainage, based on the recently proposed spot model, where the particle packing flows by local collective displacements in response to diffusing"spots'" of interstitial free volume. By comparing with discrete-element method (DEM) simulations of 55,000 spheres in a rectangular silo, we show that the spot simulation is able to approximately capture many features of drainage, such as packing statistics, particle mixing, and flow profiles. The spot simulation runs two to three orders of magnitude faster than DEM, making it an appropriate method for real-time control or optimization. We demonstrateextensions for modeling particle heaping and avalanching at the free surface, and for simulating the boundary layers of slower flow near walls. We show that the spot simulations are robust and flexible, by demonstrating that they can be used in both event-driven and fixed timestep approaches, and showing that the elastic relaxation step used in the model can be applied much less frequently and still create good results.
Date: May 22, 2009
Creator: Rycroft, Chris H.; Wong, Yee Lok & Bazant, Martin Z.
Object Type: Article
System: The UNT Digital Library
California GAMA Special Study: Examination of Water Quality of Tritium-Dead Drinking Water Wells (open access)

California GAMA Special Study: Examination of Water Quality of Tritium-Dead Drinking Water Wells

None
Date: May 22, 2012
Creator: Visser, A.; Moran, J. E.; Singleton, M. J.; Hillegonds, D. J.; Belitz, K.; Kulongoski, J. et al.
Object Type: Report
System: The UNT Digital Library
Observation of direct CP violation in the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma with B+- to D(*)K(*)+- decays (open access)

Observation of direct CP violation in the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma with B+- to D(*)K(*)+- decays

None
Date: May 22, 2013
Creator: Lees, J. P.; Poireau, V.; Tisserand, V.; /Annecy, LAPP; Grauges, E.; /Barcelona U., ECM et al.
Object Type: Article
System: The UNT Digital Library
Reach the Bottom Line of the Sbottom Search (open access)

Reach the Bottom Line of the Sbottom Search

We propose a new search strategy for directly-produced sbottoms at the LHC with a small mass splitting between the sbottom and its decayed stable neutralino. Our search strategy is based on boosting sbottoms through an energetic initial state radiation jet. In the final state, we require a large missing transverse energy and one or two b-jets besides the initial state radiation jet. We also define a few kinematic variables to further increase the discovery reach. For the case that the sbottom mainly decays into the bottom quark and the stable neutralino, we have found that even for a mass splitting as small as 10 GeV sbottoms with masses up to around 400 GeV can be excluded at the 95% confidence level with 20 inverse femtobarn data at the 8 TeV LHC.
Date: May 22, 2012
Creator: Alvarez, Ezequiel & Bai, Yang
Object Type: Article
System: The UNT Digital Library
Environmental Impacts of Wind Power Development on the Population Biology of Greater Prairie-Chickens (open access)

Environmental Impacts of Wind Power Development on the Population Biology of Greater Prairie-Chickens

Executive Summary 1. We investigated the impacts of wind power development on the demography, movements, and population genetics of Greater Prairie-Chickens (Tympanuchus cupido) at three sites in northcentral and eastern Kansas for a 7-year period. Only 1 of 3 sites was developed for wind power, the 201MW Meridan Way Wind Power Facility at the Smoky Hills site in northcentral Kansas. Our project report is based on population data for prairie chickens collected during a 2-year preconstruction period (2007-2008), a 3-year postconstruction period (2009-2011) and one final year of lek surveys (2012). Where relevant, we present preconstruction data from our field studies at reference sites in the northern Flint Hills (2007-2009) and southern Flint Hills (2006-2008). 2. We addressed seven potential impacts of wind power development on prairie chickens: lek attendance, mating behavior, use of breeding habitat, fecundity rates, natal dispersal, survival rates, and population numbers. Our analyses of pre- and postconstruction impacts are based on an analysis of covariance design where we modeled population performance as a function of treatment period, distance to eventual or actual site of the nearest wind turbine, and the interaction of these factors. Our demographic and movement data from the 6-year study period at the …
Date: May 22, 2013
Creator: Sandercock, Brett K.
Object Type: Report
System: The UNT Digital Library
Final Report - Dynamic Path Scheduling through Extensions to Generalized Multiprotocol Label Switching (GMPLS) (open access)

Final Report - Dynamic Path Scheduling through Extensions to Generalized Multiprotocol Label Switching (GMPLS)

The major accomplishments of the project are the successful software implementation of the Phase I scheduling algorithms for GMPLS Label Switched Paths (LSPs) and the extension of the IETF Path Computation Element (PCE) Protocol to support scheduling extensions. In performing this work, we have demonstrated the theoretical work of Phase I, analyzed key issues, and made relevant extensions. Regarding the software implementation, we developed a proof of concept prototype as part of our Algorithm Evaluation System (AES). This implementation uses the Linux operating system to provide software portability and will be the foundation for our commercial software. To demonstrate proof of concept, we have implemented LSP scheduling algorithms to support two of the key GMPLS switching technologies (Lambda and Packet) and support both Fixed Path (FP) and Switched Path (SP) routing. We chose Lambda and Packet because we felt it was essential to include both circuit and packet switching technologies as well as to address all-optical switching in the study. As conceptualized in Phase I, the FP algorithms use a traditional approach where the LSP uses the same physical path for the entire service duration while the innovative SP algorithms allow the physical path to vary during the service duration. …
Date: May 22, 2009
Creator: Battou, Principal Investigator: Dr. Abdella
Object Type: Report
System: The UNT Digital Library
Molecular architecture of axonemal microtubule doublets revealedby cryo-electron tomography (open access)

Molecular architecture of axonemal microtubule doublets revealedby cryo-electron tomography

The axoneme, which forms the core of eukaryotic flagella and cilia, is one of the largest macromolecular machines with a structure that is largely conserved from protists to mammals. Microtubule doublets are structural components of axonemes containing a number of proteins besides tubulin, and are usually found in arrays of nine doublets arranged around two singlet microtubules. Coordinated sliding of adjacent doublets, which involves a host of other proteins in the axoneme, produces periodic beating movements of the axoneme. We have obtained a 3D density map of intact microtubule doublets using cryo-electron tomography and image averaging. Our map, with a resolution of about 3 nm, provides insights into locations of particular proteins within the doublets and the structural features of the doublets that define their mechanical properties. We identify likely candidates for several of these non-tubulin components of the doublets. This work offers novel insight on how tubulin protofilaments and accessory proteins attach together to form the doublets and provides a structural basis for understanding doublet function in axonemes.
Date: May 22, 2006
Creator: Sui, Haixin & Downing, Kenneth H.
Object Type: Article
System: The UNT Digital Library
CENP-A mutations in Drosophila cause a BubR1-dependent earlymitotic delay without kinetochore localization of Spindle AssemblyCheckpoint components (open access)

CENP-A mutations in Drosophila cause a BubR1-dependent earlymitotic delay without kinetochore localization of Spindle AssemblyCheckpoint components

None
Date: May 22, 2006
Creator: Blower, Michael D.; Daigle, Tanya; Kaufman, Thom & Karpen, Gary H.
Object Type: Article
System: The UNT Digital Library
Dynamic response of single crystalline copper subjected to quasi-isentropic laser and gas-gun driven loading (open access)

Dynamic response of single crystalline copper subjected to quasi-isentropic laser and gas-gun driven loading

Single crystalline copper was subjected to quasi-isentropic compression via gas-gun and laser loading at pressures between 18 GPa and 59 GPa. The deformation substructure was analyzed via transmission electron microscopy (TEM). Twins and laths were evident at the highest pressures, and stacking faults and dislocation cells in the intermediate and lowest pressures, respectively. The Preston-Tonks-Wallace (PTW) constitutive description was used to model the slip-twinning process in both cases.
Date: May 22, 2006
Creator: Meyers, M; Jarmakani, H; McNaney, J; Schneider, M; Nguyen, J & Kad, B
Object Type: Article
System: The UNT Digital Library
Charm Spectroscopy, Charm Decays And New States at BaBar (open access)

Charm Spectroscopy, Charm Decays And New States at BaBar

This document presents the recent studies of Charmed hadrons at BABAR BELLE and CLEO. Here the author focuses on the recent developments on the study of D*{sub sJ}, observation of D{sup +} {yields} K{sup +} {pi}{sup 0}, D{sup 0} - {bar D}{sup 0} mixing in the doubly cabibbo-suppressed decays using D{sup 0} {yields} K{sup +}{pi}{sup +}{pi}{sup 0} and the measurement of the decay constants using the leptonic D decays.
Date: May 22, 2007
Creator: Saleem, M. & U., /Brunel
Object Type: Article
System: The UNT Digital Library
SCOPING SUMMARY FOR THE P-AREA OPERABLE UNIT (open access)

SCOPING SUMMARY FOR THE P-AREA OPERABLE UNIT

This scoping summary supports development of the combined Remedial Investigation (RI)/Baseline Risk Assessment (BRA)/Feasibility Study (FS) for the P-Area Operable Unit (PAOU), or Combined document, which will be submitted on or before 09/28/2007. The objective of this Feasibility Study scoping summary meeting is to agree on the likely response actions to be evaluated and developed as alternatives in the combined document and agree on the uncertainties identified and whether they have been adequately managed.
Date: May 22, 2007
Creator: Kupar, J; Sadika Baladi, S & Mark Amidon, M
Object Type: Report
System: The UNT Digital Library
Materials and Fabrication Issues for Large Machined Germanium Immersion Gratings (open access)

Materials and Fabrication Issues for Large Machined Germanium Immersion Gratings

LLNL has successfully fabricated small (1.5 cm{sup 2} area) germanium immersion gratings. We studied the feasibility of producing a large germanium immersion grating by means of single point diamond flycutting. Our baseline design is a 63.4o blaze echelle with a 6 cm beam diameter. Birefringence and refractive index inhomogeneity due to stresses produced by the crystal growth process are of concern. Careful selection of the grating blank and possibly additional annealing to relieve stress will be required. The Large Optics Diamond Turning Machine (LODTM) at LLNL is a good choice for the fabrication. It can handle parts up to 1.5 meter in diameter and 0.5 meter in length and is capable of a surface figure accuracy of better than 28 nm rms. We will describe the machine modifications and the machining process for a large grating. A next generation machine, the Precision Optical Grinder and Lathe (POGAL), currently under development has tighter specifications and could produce large gratings with higher precision.
Date: May 22, 2006
Creator: Kuzmenko, P J; Davis, P J; Little, S L & Hale, L C
Object Type: Article
System: The UNT Digital Library
Stab Sensitivity of Energetic Nanolaminates (open access)

Stab Sensitivity of Energetic Nanolaminates

This work details the stab ignition, small-scale safety, and energy release characteristics of bimetallic Al/Ni(V) and Al/Monel energetic nanolaminate freestanding thin films. The influence of the engineered nanostructural features of the energetic multilayers is correlated with both stab initiation and small-scale energetic materials testing results. Structural parameters of the energetic thin films found to be important include the bi-layer period, total thickness of the film, and presence or absence of aluminum coating layers. In general the most sensitive nanolaminates were those that were relatively thick, possessed fine bi-layer periods, and were not coated. Energetic nanolaminates were tested for their stab sensitivity as freestanding continuous parts and as coarse powders. The stab sensitivity of mock M55 detonators loaded with energetic nanolaminate was found to depend strongly upon both the particle size of the material and the configuration of nanolaminate material, in the detonator cup. In these instances stab ignition was observed with input energies as low as 5 mJ for a coarse powder with an average particle dimension of 400 {micro}m. Selected experiments indicate that the reacting nanolaminate can be used to ignite other energetic materials such as sol-gel nanostructured thermite, and conventional thermite that was either coated onto the multilayer …
Date: May 22, 2006
Creator: Gash, A; Barbee, T & Cervantes, O
Object Type: Article
System: The UNT Digital Library
Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics (open access)

Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics

The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over …
Date: May 22, 2006
Creator: Cannon, W. Roger
Object Type: Report
System: The UNT Digital Library
Results of the development and field demonstration program on cavitation descaling techniques for pipes and tubes used in geothermal energy plants. Volume I (open access)

Results of the development and field demonstration program on cavitation descaling techniques for pipes and tubes used in geothermal energy plants. Volume I

The conversion of geothermal energy into usable electrical power has become increasingly important to the overall national energy needs. A major area of technical interest which has resulted from the initial development of geothermal power plants is the scale formation developed in the facility pipes and related components. This scale formation is due to the concentration of minerals in the geothermal water and steam. The current state-of-technology utilized for descaling consists of a combination of sandblasting, water blasting, acid soaking and scraping. These cleaning methods, used individually or collectively, do not provide an acceptable descaling operation due to excessive facility downtime and cost.
Date: May 22, 1978
Creator: Graham, F.C.; Thiruvengadam, A.P. & Hochrein, A.A., Jr.
Object Type: Report
System: The UNT Digital Library
Influence of Black Annealing Oxide Scale on the Anodic Behavior of Alloy 22 (open access)

Influence of Black Annealing Oxide Scale on the Anodic Behavior of Alloy 22

The resistance of Alloy 22 (N06022) to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. The effect of influencing variables such as temperature, applied potential, chloride concentration and nitrate inhibitor concentration have been addressed previously. At this time, it was important to address the effect an oxide film or scale that forms during the high temperature annealing process or solution heat treatment (SHT) and its subsequent water quenching. Electrochemical tests such as cyclic potentiodynamic polarization (CPP) have been carried out to determine the repassivation potential for localized corrosion and to assess the mode of attack on the specimens. Tests have been carried out in parallel using mill annealed (MA) specimens free from oxide on the surface. The comparative testing was carried out in six different electrolyte solutions at temperatures ranging from 60 C to 100 C. Results show that the repassivation potential of the specimens containing the black anneal oxide film on the surface was practically the same or higher as the repassivation potential for oxide-free specimens.
Date: May 22, 2006
Creator: Rebak, R. B.; Etien, R. A.; Gordon, S. R. & Ilevbare, G. O.
Object Type: Article
System: The UNT Digital Library
Characterizing Electron Temperature Gradient Turbulence Via Numerical Simulation (open access)

Characterizing Electron Temperature Gradient Turbulence Via Numerical Simulation

Numerical simulations of electron temperature gradient (ETG) turbulence are presented which characterize the ETG fluctuation spectrum, establish limits to the validity of the adiabatic ion model often employed in studying ETG turbulence, and support the tentative conclusion that plasmaoperating regimes exist in which ETG turbulence produces sufficient electron heat transport to be experimentally relevant. We resolve prior controversies regarding simulation techniques and convergence by benchmarking simulations of ETG turbulence from four microturbulence codes, demonstrating agreement on the electron heat flux, correlation functions, fluctuation intensity, and rms flow shear at fixed simulation cross section and resolution in the plane perpendicular to the magnetic field. Excellent convergence of both continuum and particle-in-cell codes with time step and velocity-space resolution is demonstrated, while numerical issues relating to perpendicular (to the magnetic field) simulation dimensions and resolution are discussed. A parameter scan in the magnetic shear, s, demonstrates that the adiabatic ion model is valid at small values of s (s &lt; 0.4 for the parameters used in this scan) but breaks down at higher magnetic shear. A proper treatment employing gyrokinetic ions reveals a steady increase in the electron heat transport with increasing magnetic shear, reaching electron heat transport rates consistent with analyses …
Date: May 22, 2006
Creator: Nevins, W M; Candy, J; Cowley, S; Dannert, T; Dimits, A; Dorland, W et al.
Object Type: Article
System: The UNT Digital Library
Determining (n,f) cross sections for actinide nuclei indirectly: An examination of the Surrogate Ratio Method (open access)

Determining (n,f) cross sections for actinide nuclei indirectly: An examination of the Surrogate Ratio Method

The validity of the Surrogate Ratio method for determining (n,f) cross sections for actinide nuclei is examined. This method relates the ratio of two compound-nucleus reaction cross sections to a ratio of coincidence events from two measurements in which the same compound nuclei are formed via a direct reaction. With certain assumptions, the method allows one of the cross sections to be inferred if the other is known. We develop a nuclear reaction-model simulation to investigate whether the assumptions underlying the Ratio approach are valid and employ these simulations to assess whether the cross sections obtained indirectly by applying a Ratio analysis agree with the expected results. In particular, we simulate Surrogate experiments that allow us to determine fission cross sections for selected actinide nuclei. The nuclei studied, {sup 233}U and {sup 235}U, are very similar to those considered in recent Surrogate experiments. We find that in favorable cases the Ratio method provides useful estimates of the desired cross sections, and we discuss some of the limitations of the approach.
Date: May 22, 2006
Creator: Escher, J E & Dietrich, F S
Object Type: Article
System: The UNT Digital Library
DECOMMISSIONING OF THE 247-F FUEL MANUFACTURING FACILITY AT THE SAVANNAH RIVER SITE (open access)

DECOMMISSIONING OF THE 247-F FUEL MANUFACTURING FACILITY AT THE SAVANNAH RIVER SITE

Building 247-F at SRS was a roughly 110,000 ft{sup 2} two-story facility designed and constructed during the height of the cold war naval buildup to provide additional naval nuclear fuel manufacturing capacity in early 1980s. The building layout is shown in Fig. 1. A photograph of the facility is shown in Fig. 2. The manufacturing process employed a wide variety of acids, bases, and other hazardous materials. As the cold war wound down, the need for naval fuel declined. Consequently, the facility was shut down and underwent initial deactivation. All process systems were flushed with water and drained using the existing process drain valves. However, since these drains were not always installed at the lowest point in piping and equipment systems, a significant volume of liquid remained after initial deactivation was completed in 1990. At that time, a non-destructive assay of the process area identified approximately 17 (+/- 100%) kg of uranium held up in equipment and piping.
Date: May 22, 2007
Creator: Santos, J & Stephen Chostner, S
Object Type: Article
System: The UNT Digital Library
Resonance Parameter Measurements and Analysis of Gadolinium (open access)

Resonance Parameter Measurements and Analysis of Gadolinium

None
Date: May 22, 2006
Creator: Leinweber, G.; Barry, D. P.; Trbovich, M. J.; Burke, J. A.; Drindak, N. J.; Knox, H. D. et al.
Object Type: Report
System: The UNT Digital Library