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Adaptation of a cubic smoothing spline algortihm for multi-channel data stitching at the National Ignition Facility (open access)

Adaptation of a cubic smoothing spline algortihm for multi-channel data stitching at the National Ignition Facility

Some diagnostics at the National Ignition Facility (NIF), including the Gamma Reaction History (GRH) diagnostic, require multiple channels of data to achieve the required dynamic range. These channels need to be stitched together into a single time series, and they may have non-uniform and redundant time samples. We chose to apply the popular cubic smoothing spline technique to our stitching problem because we needed a general non-parametric method. We adapted one of the algorithms in the literature, by Hutchinson and deHoog, to our needs. The modified algorithm and the resulting code perform a cubic smoothing spline fit to multiple data channels with redundant time samples and missing data points. The data channels can have different, time-varying, zero-mean white noise characteristics. The method we employ automatically determines an optimal smoothing level by minimizing the Generalized Cross Validation (GCV) score. In order to automatically validate the smoothing level selection, the Weighted Sum-Squared Residual (WSSR) and zero-mean tests are performed on the residuals. Further, confidence intervals, both analytical and Monte Carlo, are also calculated. In this paper, we describe the derivation of our cubic smoothing spline algorithm. We outline the algorithm and test it with simulated and experimental data.
Date: December 28, 2010
Creator: Brown, C; Adcock, A; Azevedo, S; Liebman, J & Bond, E
System: The UNT Digital Library
Numerical simulation studies of the long-term evolution of a CO2 plume in a saline aquifer with a sloping caprock (open access)

Numerical simulation studies of the long-term evolution of a CO2 plume in a saline aquifer with a sloping caprock

We have used the TOUGH2-MP/ECO2N code to perform numerical simulation studies of the long-term behavior of CO{sub 2} stored in an aquifer with a sloping caprock. This problem is of great practical interest, and is very challenging due to the importance of multi-scale processes. We find that the mechanism of plume advance is different from what is seen in a forced immiscible displacement, such as gas injection into a water-saturated medium. Instead of pushing the water forward, the plume advances because the vertical pressure gradients within the plume are smaller than hydrostatic, causing the groundwater column to collapse ahead of the plume tip. Increased resistance to vertical flow of aqueous phase in anisotropic media leads to reduced speed of updip plume advancement. Vertical equilibrium models that ignore effects of vertical flow will overpredict the speed of plume advancement. The CO{sub 2} plume becomes thinner as it advances, yet the speed of advancement remains constant over the entire simulation period of up to 400 years, with migration distances of more than 80 km. Our simulations include dissolution of CO{sub 2} into the aqueous phase and associated density increase, and molecular diffusion. However, no convection develops in the aqueous phase because it …
Date: December 28, 2010
Creator: Pruess, K. & Nordbotten, J.
System: The UNT Digital Library
DEVELOPMENT AND DEPLOYMENT OF VACUUM SALT DISTILLATION AT THE SAVANNAH RIVER SITE (open access)

DEVELOPMENT AND DEPLOYMENT OF VACUUM SALT DISTILLATION AT THE SAVANNAH RIVER SITE

The Savannah River Site has a mission to dissolve fissile materials and disposition them. The primary fissile material is plutonium dioxide (PuO{sub 2}). To support dissolution of these materials, the Savannah River National Laboratory (SRNL) designed and demonstrated a vacuum salt distillation (VSD) apparatus using both representative radioactive samples and non-radioactive simulant materials. Vacuum salt distillation, through the removal of chloride salts, increases the quantity of materials suitable for processing in the site's HB-Line Facility. Small-scale non-radioactive experiments at 900-950 C show that >99.8 wt % of the initial charge of chloride salt distilled from the sample boat with recovery of >99.8 wt % of the ceric oxide (CeO{sub 2}) - the surrogate for PuO{sub 2} - as a non-chloride bearing 'product'. Small-scale radioactive testing in a glovebox demonstrated the removal of sodium chloride (NaCl) and potassium chloride (KCl) from 13 PuO{sub 2} samples. Chloride concentrations were distilled from a starting concentration of 1.8-10.8 wt % to a final concentration <500 mg/kg chloride. Initial testing of a non-radioactive, full-scale production prototype is complete. A designed experiment evaluated the impact of distillation temperature, time at temperature, vacuum, product depth, and presence of a boat cover. Significant effort has been devoted to …
Date: October 28, 2010
Creator: Pierce, R.; Pak, D. & Edwards, T.
System: The UNT Digital Library
Electronic structure of fully epitaxial Co2TiSn thin films (open access)

Electronic structure of fully epitaxial Co2TiSn thin films

In this article we report on the properties of thin films of the full Heusler compound Co{sub 2}TiSn prepared by DC magnetron co-sputtering. Fully epitaxial, stoichiometric films were obtained by deposition on MgO (001) substrates at substrate temperatures above 600 C. The films are well ordered in the L2{sub 1} structure, and the Curie temperature exceeds slightly the bulk value. They show a significant, isotropic magnetoresistance and the resistivity becomes strongly anomalous in the paramagnetic state. The films are weakly ferrimagnetic, with nearly 1 {mu}{sub B} on the Co atoms, and a small antiparallel Ti moment, in agreement with theoretical expectations. From comparison of x-ray absorption spectra on the Co L{sub 3,2} edges, including circular and linear magnetic dichroism, with ab initio calculations of the x-ray absorption and circular dichroism spectra we infer that the electronic structure of Co{sub 2}TiSn has essentially non-localized character. Spectral features that have not been explained in detail before, are explained here in terms of the final state band structure.
Date: October 28, 2010
Creator: Meinert, Markus; Schmalhorst, Jan; Wulfmeier, Hendrik; Reiss, Gunter; Arenholz, Elke; Graf, Tanja et al.
System: The UNT Digital Library
Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior (open access)

Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior

Vacuum Ultraviolet (VUV) photoionization mass spectrometry has been used to measure the evolution of chemical composition for two distinct organic aerosol types as they are passed through a thermodenuder at different temperatures. The two organic aerosol types considered are primary lubricating oil (LO) aerosol and secondary aerosol from the alpha-pinene + O3 reaction (alphaP). The evolution of the VUV mass spectra for the two aerosol types with temperature are observed to differ dramatically. For LO particles, the spectra exhibit distinct changes with temperature in which the lower m/z peaks, corresponding to compounds with higher vapor pressures, disappear more rapidly than the high m/z peaks. In contrast, the alphaP aerosol spectrum is essentially unchanged by temperature even though the particles experience significant mass loss due to evaporation. The variations in the LO spectra are found to be quantitatively in agreement with expectations from absorptive partitioning theory whereas the alphaP spectra suggest that the evaporation of alphaP derived aerosol appears to not be governed by partitioning theory. We postulate that this difference arises from the alphaP particles existing as in a glassy state instead of having the expected liquid-like behavior. To reconcile these observations with decades of aerosol growth measurements, which indicate …
Date: October 28, 2010
Creator: Davis, UC; Cappa, Christopher D. & Wilson, Kevin R.
System: The UNT Digital Library
Improvement of Laser Damage Resistance and Diffraction Efficiency of Multilayer Dielectric Diffraction Gratings by HF-Etchback Linewidth Tailoring (open access)

Improvement of Laser Damage Resistance and Diffraction Efficiency of Multilayer Dielectric Diffraction Gratings by HF-Etchback Linewidth Tailoring

Multilayer dielectric (MLD) diffraction gratings for Petawatt-class laser systems possess unique laser damage characteristics. Details of the shape of the grating lines and the concentration of absorbing impurities on the surface of the grating structures both have strong effects on laser damage threshold. It is known that electric field enhancement in the solid material comprising the grating lines varies directly with the linewidth and inversely with the line height for equivalent diffraction efficiency. Here, they present an overview of laser damage characteristics of MLD gratings, and describe a process for post-processing ion-beam etched grating lines using very dilute buffered hydrofluoric acid solutions. This process acts simultaneously to reduce grating linewidth and remove surface contaminants, thereby improving laser damage thresholds through two pathways.
Date: October 28, 2010
Creator: Nguyen, H T; Larson, C C & Britten, J A
System: The UNT Digital Library
Simulation of Infrared Laser Heating of Silica Using Heat Conduction and Multifrequency Radiation Diffusion Equations Adapted for Homogeneous Refractive Lossy Media (open access)

Simulation of Infrared Laser Heating of Silica Using Heat Conduction and Multifrequency Radiation Diffusion Equations Adapted for Homogeneous Refractive Lossy Media

Localized, transient heating of materials using micro-scale, highly absorbing laser light has been used in many industries to anneal, melt and ablate material with high precision. Accurate modeling of the relative contributions of conductive, convective and radiative losses as a function of laser parameters is essential to optimizing micro-scale laser processing of materials. In bulk semi-transparent materials such as silicate glass melts, radiation transport is known to play a significantly larger role as the temperature increases. Conventionally, radiation is treated in the frequency-averaged diffusive limit (Rosseland approximation). However, the role and proper treatment of radiative processes under rapidly heated, high thermal gradient conditions, often created through laser-matter interactions, is at present not clear. Starting from the radiation transport equation for homogeneous, refractive lossy media, they derive the corresponding time-dependent multi-frequency diffusion equations. Zeroth and first moments of the transport equation couple the energy density, flux and pressure tensor. The system is closed by neglecting the temporal derivative of the flux and replacing the pressure tensor by its diagonal analogue. The radiation equations are coupled to a diffusion equation for the matter temperature. They are interested in modeling infrared laser heating of silica over sub-millimeter length scales, and at possibly rapid …
Date: October 28, 2010
Creator: Shestakov, A I; Matthews, M J; Vignes, R M & Stolken, J S
System: The UNT Digital Library
Study of the neutron damage on electronics at the National Ignition Facility (open access)

Study of the neutron damage on electronics at the National Ignition Facility

The NIF environment is very complex leading to a large and non trivial radiation background. A shield surrounding the electronics is required to lower the neutron background to less than 1e7 n/cm{sup 2}. Moving electronics to behind the 6 foot-thick target bay wall is the best shield.
Date: October 28, 2010
Creator: Dauffy, L S; Mcnaney, J M & Khater, H Y
System: The UNT Digital Library
Actinic imaging and evaluation of phase structures on EUV lithography masks (open access)

Actinic imaging and evaluation of phase structures on EUV lithography masks

The authors describe the implementation of a phase-retrieval algorithm to reconstruct phase and complex amplitude of structures on EUV lithography masks. Many native defects commonly found on EUV reticles are difficult to detect and review accurately because they have a strong phase component. Understanding the complex amplitude of mask features is essential for predictive modeling of defect printability and defect repair. Besides printing in a stepper, the most accurate way to characterize such defects is with actinic inspection, performed at the design, EUV wavelength. Phase defect and phase structures show a distinct through-focus behavior that enables qualitative evaluation of the object phase from two or more high-resolution intensity measurements. For the first time, phase of structures and defects on EUV masks were quantitatively reconstructed based on aerial image measurements, using a modified version of a phase-retrieval algorithm developed to test optical phase shifting reticles.
Date: September 28, 2010
Creator: Mochi, Iacopo; Goldberg, Kenneth & Huh, Sungmin
System: The UNT Digital Library
Benchmarking ICRF simulations for ITER (open access)

Benchmarking ICRF simulations for ITER

Abstract Benchmarking of full-wave solvers for ICRF simulations is performed using plasma profiles and equilibria obtained from integrated self-consistent modeling predictions of four ITER plasmas. One is for a high performance baseline (5.3 T, 15 MA) DT H-mode plasma. The others are for half-field, half-current plasmas of interest for the pre-activation phase with bulk plasma ion species being either hydrogen or He4. The predicted profiles are used by seven groups to predict the ICRF electromagnetic fields and heating profiles. Approximate agreement is achieved for the predicted heating power partitions for the DT and He4 cases. Profiles of the heating powers and electromagnetic fields are compared.
Date: September 28, 2010
Creator: Budny, R. V.; Berry, L.; Bilato, R.; Bonoli, P.; Brambilla, M.; Dumont, R. J. et al.
System: The UNT Digital Library
CRUSH TESTING OF 9977 GENERAL PURPOSE FISSILE PACKAGINGS (open access)

CRUSH TESTING OF 9977 GENERAL PURPOSE FISSILE PACKAGINGS

The 9977 General Purpose Fissile Package (GPFP) was designed in response to the adoption of the crush test requirement in the US regulations for packages for radioactive materials (10 CFR 71). This presentation on crush testing of the 9977 GPFP Reviews origins of Crush Test Requirements and implementation of crush test requirements in 10 CFR 71. SANDIA testing performed to support the rule making is reviewed. The differences in practice, on the part of the US Department of Energy from those required by the NRC for commercial purposes, are explained. The design features incorporated into the 9977 GPFP to enable it to withstand the crush test and the crush tests performed on the 9977 are described. Lessons learned from crush testing of GPFP packagings are given.
Date: July 28, 2010
Creator: Smith, A.
System: The UNT Digital Library
Effects of Quartz Particle Size and Sucrose Addition on Melting Behavior of a Melter Feed for High-Level Glass (open access)

Effects of Quartz Particle Size and Sucrose Addition on Melting Behavior of a Melter Feed for High-Level Glass

The behavior of melter feed (a mixture of nuclear waste and glass-forming additives) during waste-glass processing has a significant impact on the rate of the vitrification process. We studied the effects of silica particle size and sucrose addition on the volumetric expansion (foaming) of a high-alumina feed and the rate of dissolution of silica particles in feed samples heated at 5 C/min up to 1200 C. The initial size of quartz particles in feed ranged from 5 to 195 {micro}m. The fraction of the sucrose added ranged from 0 to 0.20 g per g glass. Extensive foaming occurred only in feeds with 5-{micro}m quartz particles; particles {ge}150 {micro}m formed clusters. Particles of 5 {micro}m completely dissolved by 900 C whereas particles {ge}150 {micro}m did not fully dissolve even when the temperature reached 1200 C. Sucrose addition had virtually zero impact on both foaming and the dissolution of silica particles. Over 100 sites in the United States are currently tasked with the storage of nuclear waste. The largest is the Hanford Site located in southeastern Washington State with 177 subterranean tanks containing over fifty-million gallons of nuclear waste from plutonium production from 1944 through 1987. This waste will be vitrified at …
Date: July 28, 2010
Creator: Marcial, J.; Kruger, A. A.; Hrma, P. R.; Schweiger, M. J.; Swearingen, K. J.; We, Tegrotenhuis, W. E. et al.
System: The UNT Digital Library
Using End-to-End Bandwidth Estimates for Anomaly Detection beyond Enterprise Boundaries (open access)

Using End-to-End Bandwidth Estimates for Anomaly Detection beyond Enterprise Boundaries

None
Date: July 28, 2010
Creator: Hussain, Fida; Kalim, Umar; Latif, Noman & Khayam, Ali
System: The UNT Digital Library
Bollywood and Beyond: Hinduism Changing the World (open access)

Bollywood and Beyond: Hinduism Changing the World

Article discussing research on the ideals of Hinduism, such as pluralism, dharma, ritam, and nonviolence holding important lessons for the future of Hinduism in particular and for humanity in general.
Date: June 28, 2010
Creator: Jain, Pankaj
System: The UNT Digital Library
A COMPARISON OF GADRAS SIMULATED AND MEASURED GAMMA RAY SPECTRA (open access)

A COMPARISON OF GADRAS SIMULATED AND MEASURED GAMMA RAY SPECTRA

Gamma-ray radiation detection systems are continuously being developed and improved for detecting the presence of radioactive material and for identifying isotopes present. Gamma-ray spectra, from many different isotopes and in different types and thicknesses of attenuation material and matrixes, are needed to evaluate the performance of these devices. Recently, a test and evaluation exercise was performed by the Savannah River National Laboratory that required a large number of gamma-ray spectra. Simulated spectra were used for a major portion of the testing in order to provide a pool of data large enough for the results to be statistically significant. The test data set was comprised of two types of data, measured and simulated. The measured data were acquired with a hand-held Radioisotope Identification Device (RIID) and simulated spectra were created using Gamma Detector Response and Analysis Software (GADRAS, Mitchell and Mattingly, Sandia National Laboratory). GADRAS uses a one-dimensional discrete ordinate calculation to simulate gamma-ray spectra. The measured and simulated spectra have been analyzed and compared. This paper will discuss the results of the comparison and offer explanations for spectral differences.
Date: June 28, 2010
Creator: Jeffcoat, R. & Salaymeh, S.
System: The UNT Digital Library
Confirmation of the Younger Dryas boundary (YDB) data at Murray Springs, AZ (open access)

Confirmation of the Younger Dryas boundary (YDB) data at Murray Springs, AZ

None
Date: June 28, 2010
Creator: Firestone, Richard B.; West, Allen & Bunch, Ted E.
System: The UNT Digital Library
Design and Construction of a Prototype Solenoid Coil for MICE Coupling Magnets (open access)

Design and Construction of a Prototype Solenoid Coil for MICE Coupling Magnets

A superconducting coupling solenoid mounted around four conventional RF cavities, which produces up to 2.6 T central magnetic field to keep the muons within the cavities, is to be used for the Muon Ionization Cooling Experiment (MICE). The coupling coil made from copper matrix NbTi conductors is the largest of three types of magnets in MICE both in terms of 1.5 m inner diameter and about 13MJ stored magnetic energy at full operation current of 210A. The stress induced inside the coil assembly during cool down and magnet charging is relatively high. In order to validate the design method and develop the coil winding technique with inside-wound SC splices required for the coupling coil, a prototype coil made from the same conductor and with the same diameter and thickness but only one-fourth long as the coupling coil was designed and fabricated by ICST. The prototype coil was designed to be charged to strain conditions that are equivalent or greater than would be encountered in the coupling coil. This paper presents detailed design of the prototype coil as well as developed coil winding skills. The analyses on stress in the coil assembly and quench process were carried out.
Date: June 28, 2010
Creator: Wang, Li; Pan, Heng; Guo, XingLong; Xu, FengYu; Liu, XiaoKun; Wu, Hong et al.
System: The UNT Digital Library
Effects of Slip Planes on Stresses in MICE Coupling Solenoid Coil Assembly (open access)

Effects of Slip Planes on Stresses in MICE Coupling Solenoid Coil Assembly

The MICE superconducting coupling solenoid magnet is made from copper matrix Nb-Ti conductors with inner radius of 750 mm, length of 285 mm and thickness of 110.4 mm at room temperature. The coil is to be wound on a mandrel made of aluminum. The peak magnetic field on the conductor is about 7.3 T when fully charged at 210 A. High magnetic field and large size make the stress inside the coupling coil assembly relatively high during cool down and full energizing. The shear stress between coil winding and aluminum casing may cause premature quench. To avoid quench potential induced by stress, slip planes were designed for the coil assembly. In this paper, FE models with and without slip planes for it have been developed to simulate the stresses during the process including winding, cooling down and charging. The stress distribution in the coil assembly with and without slip planes was investigated. The results show that slip planes with low friction coefficients can improve the stress condition in the coil, especially reduce the shear stress largely so that improve the stability.
Date: June 28, 2010
Creator: Wang, Li; Pan, Heng; Wu, Hong; Guo, XingLong; Cheng, Y. & Green, Michael A
System: The UNT Digital Library
Progress on Design and Construction of a MuCool Coupling Solenoid Magnet (open access)

Progress on Design and Construction of a MuCool Coupling Solenoid Magnet

The MuCool program undertaken by the US Neutrino Factory and Muon Collider Collaboration is to study the behavior of muon ionization cooling channel components. A single superconducting coupling solenoid magnet is necessary to pursue the research and development work on the performance of high gradient, large size RF cavities immersed in magnetic field, which is one of the main challenges in the practical realization of ionization cooling of muons. The MuCool coupling magnet is to be built using commercial copper based niobium titanium conductors and cooled by two cryo-coolers with each cooling capacity of 1.5 W at 4.2 K. The solenoid magnet will be powered by using a single 300A power supply through a single pair of binary leads that are designed to carry a maximum current of 210A. The magnet is to be passively protected by cold diodes and resistors across sections of the coil and by quench back from the 6061 Al mandrel in order to lower the quench voltage and the hot spot temperature. The magnet is currently under construction. This paper presents the updated design and fabrication progress on the MuCool coupling magnet.
Date: June 28, 2010
Creator: Wang, L.; Liu, Xiao Kun; Xu, FengYu; Li, S.; Pan, Heng; Wu, Hong et al.
System: The UNT Digital Library
Thermal Stability Analysis for Superconducting Coupling Coil in MICE (open access)

Thermal Stability Analysis for Superconducting Coupling Coil in MICE

The superconducting coupling coil to be used in the Muon Ionization Cooling Experiment (MICE) with inner radius of 750 mm, length of 285 mm and thickness of 110.4 mm will be cooled by a pair of 1.5 W at 4.2 K cryo-coolers. When the coupling coil is powered to 210 A, it will produce about 7.3 T peak magnetic field at the conductor and it will have a stored energy of 13 MJ. A key issue for safe operation of the coupling coil is the thermal stability of the coil during a charge and discharge. The magnet and its cooling system are designed for a rapid discharge where the magnet is to be discharged in 5400 seconds. The numerical simulation for the thermal stability of the MICE coupling coil has been done using ANSYS. The analysis results show that the superconducting coupling coil has a good stability and can be charged and discharged safely.
Date: June 28, 2010
Creator: Wu, Hong; Wang, Li; Pan, Heng; Guo, XingLong & Green, M.A.
System: The UNT Digital Library
Classifying genes to the correct Gene Ontology Slim term in Saccharomyces cerevisiae using neighbouring genes with classification learning (open access)

Classifying genes to the correct Gene Ontology Slim term in Saccharomyces cerevisiae using neighbouring genes with classification learning

Article discussing research on classifying genes to the correct gene ontology slim term in Saccharomyces cerevisiae using neighbouring genes with classification learning.
Date: May 28, 2010
Creator: Amthauer, Heather A. & Tsatsoulis, C. (Costas), 1962-
System: The UNT Digital Library
Thin Silicon MEMS Contact-Stress Sensor (open access)

Thin Silicon MEMS Contact-Stress Sensor

This thin, MEMS contact-stress sensor continuously and accurately measures time-varying, solid interface loads over tens of thousands of load cycles. The contact-stress sensor is extremely thin (150 {mu}m) and has a linear output with an accuracy of {+-} 1.5% FSO.
Date: May 28, 2010
Creator: Kotovksy, J; Tooker, A & Horsley, D
System: The UNT Digital Library
Measurement of the gamma gamma* to eta_c transition form factor (open access)

Measurement of the gamma gamma* to eta_c transition form factor

The authors study the reaction e{sup +}e{sup -} {yields} e{sup +}e{sup -} {eta}{sub c}, {eta}{sub c} {yields} K{sub S}K{sup {+-}}{pi}{sup {-+}} and obtain {eta}{sub c} mass and width values 2982.2 {+-} 0.4 {+-} 1.6 MeV/c{sup 2} and 31.7 {+-} 1.2 {+-} 0.8 MeV, respectively. They find {Lambda}({eta}{sub c} {yields} {gamma}{gamma}){Beta}({eta}{sub c} {yields} K{bar K}{pi}) = 0.374 {+-} 0.009 {+-} 0.031 keV, and measure the {gamma}{gamma}* {yields} {eta}{sub c} transition form factor in the momentum transfer range from 2 to 50 GeV{sup 2}. The analysis is based on 469 fb{sup -1} of integrated luminosity collected at PEP-II with the BABAR detector at e{sup +}e{sup -} center-of-mass energies near 10.6 GeV.
Date: April 28, 2010
Creator: Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E. et al.
System: The UNT Digital Library
Non-diffusive spin dynamics in a two-dimensional electron gas (open access)

Non-diffusive spin dynamics in a two-dimensional electron gas

We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wavevector range from zero to 6 x 10{sup 4} cm{sup -1}. We find that the spin polarization lifetime is maximal at nonzero wavevector, in contrast with expectation based on ordinary spin diffusion, but in quantitative agreement with recent theories that treat diffusion in the presence of spin-orbit coupling.
Date: April 28, 2010
Creator: Weber, C.P.
System: The UNT Digital Library