Edge preserving smoothing and segmentation of 4-D images via transversely isotropic scale-space processing and fingerprint analysis (open access)

Edge preserving smoothing and segmentation of 4-D images via transversely isotropic scale-space processing and fingerprint analysis

Enhancements are described for an approach that unifies edge preserving smoothing with segmentation of time sequences of volumetric images, based on differential edge detection at multiple spatial and temporal scales. Potential applications of these 4-D methods include segmentation of respiratory gated positron emission tomography (PET) transmission images to improve accuracy of attenuation correction for imaging heart and lung lesions, and segmentation of dynamic cardiac single photon emission computed tomography (SPECT) images to facilitate unbiased estimation of time-activity curves and kinetic parameters for left ventricular volumes of interest. Improved segmentation of lung surfaces in simulated respiratory gated cardiac PET transmission images is achieved with a 4-D edge detection operator composed of edge preserving 1-D operators applied in various spatial and temporal directions. Smoothing along the axis of a 1-D operator is driven by structure separation seen in the scale-space fingerprint, rather than by image contrast. Spurious noise structures are reduced with use of small-scale isotropic smoothing in directions transverse to the 1-D operator axis. Analytic expressions are obtained for directional derivatives of the smoothed, edge preserved image, and the expressions are used to compose a 4-D operator that detects edges as zero-crossings in the second derivative in the direction of the …
Date: January 19, 2004
Creator: Reutter, Bryan W.; Algazi, V. Ralph; Gullberg, Grant T. & Huesman, Ronald H.
Object Type: Article
System: The UNT Digital Library
Performance of the Keck Observatory Adaptive Optics System (open access)

Performance of the Keck Observatory Adaptive Optics System

In this paper, the adaptive optics (AO) system at the W.M. Keck Observatory is characterized. The authors calculate the error budget of the Keck AO system operating in natural guide star mode with a near infrared imaging camera. By modeling the control loops and recording residual centroids, the measurement noise and band-width errors are obtained. The error budget is consistent with the images obtained. Results of sky performance tests are presented: the AO system is shown to deliver images with average Strehl ratios of up to 0.37 at 1.58 {micro}m using a bright guide star and 0.19 for a magnitude 12 star.
Date: January 19, 2004
Creator: van Dam, M. A.; Mignant, D. L. & Macintosh, B. A.
Object Type: Article
System: The UNT Digital Library
A study of surface film formation on LiNi0.8Co0.15Al0.05O2 cathodes u sing attenuated total reflection infrared spectroscopy (open access)

A study of surface film formation on LiNi0.8Co0.15Al0.05O2 cathodes u sing attenuated total reflection infrared spectroscopy

The surface films formed on commercial LiNi0.8Co0.15Al0.05O2 cathodes (ATD Gen2) charged from 3.75V to 4.2V vs. Li/Li+ in EC:DEC - 1M LiPF6 were analyzed using ex-situ Fourier transform infrared spectroscopy (FTIR) with the attenuated total reflection (ATR) technique. A surface layer of Li2CO3 is present on the virgin cathode, probably from reaction of the active material with air during the cathode preparation procedure. The Li2CO3 layer disappeared even after soaking in the electrolyte, indicating that the layer dissolved into the electrolyte possibly even before potential cycling of the electrode. IR features only from the binder (PVdF) and a trace of polyamide from the Al current collector were observed on the surfaces of cathodes charged to below 4.2 V, i.e., no surface species from electrolyte oxidation. Some new IR features were, however, found on the cathode charged to 4.2 V and higher. An electrolyte oxidation product was observed that appeared to contain dicarbonyl anhydride and (poly)ester functionalities. The reaction appears to be an indirect electrochemical oxidation with overcharging (removal of > 0.6 Li ions) destabilizing oxygen in the oxide lattice resulting in oxygen transfer to the solvent molecules.
Date: January 19, 2004
Creator: Song, S.-W.; Zhuang, G.V. & Ross Jr., P.N.
Object Type: Article
System: The UNT Digital Library
Analysis of High-n Dielectronic Rydberg Satellites in the Spectra of Na-like ZnXX and Mg-like ZnXIX (open access)

Analysis of High-n Dielectronic Rydberg Satellites in the Spectra of Na-like ZnXX and Mg-like ZnXIX

We have observed spectra from highly charged zinc ions in a variety of laser-produced plasmas. Spectral features that are Na- and Mg-like satellites to high-n Rydberg transitions in the Ne-like ZnXXI spectrum are analyzed and modeled. Identifications and analysis are made by comparison with highly accurate atomic structure calculations and steady state collisional-radiative models. Each observed ZnXX and ZnXIX feature comprises up to {approx} 2 dozen individual transitions, these transitions are excited principally by dielectronic recombination through autoionizing levels in Na- and Mg-like Zn{sup 19+} Zn{sup 18+}. We find these satellites to be ubiquitous in laser-produced plasmas formed by lasers with pulse lengths that span four orders of magnitude, from 1 ps to {approx} 10 ns. The diagnostic potential of these Rydberg satellite lines is demonstrated.
Date: February 19, 2004
Creator: Petrocelli, G; Vinogradov, V I; Magunov, A I; Flora, F; Martellucci, S; Matafonov, A P et al.
Object Type: Article
System: The UNT Digital Library
Anomalous Skin Effect for Anisotropic Electron Velocity Distribution Function (open access)

Anomalous Skin Effect for Anisotropic Electron Velocity Distribution Function

The anomalous skin effect in a plasma with a highly anisotropic electron velocity distribution function (EVDF) is very different from skin effect in a plasma with the isotropic EVDF. An analytical solution was derived for the electric field penetrated into plasma with the EVDF described as a Maxwellian with two temperatures Tx >> Tz, where x is the direction along the plasma boundary and z is the direction perpendicular to the plasma boundary. The skin layer was found to consist of two distinctive regions of width of order nTx/w and nTz/w, where nTx,z/w = (Tx,z/m)1/2 is the thermal electron velocity and w is the incident wave frequency.
Date: February 19, 2004
Creator: Kaganovich, Igor; Startsev, Edward & Shvets, Gennady
Object Type: Report
System: The UNT Digital Library
CO2 SELECTIVE CERAMIC MEMBRANE FOR WATER-GAS SHIFT REACTION WITH CONCOMITANT RECOVERY OF CO2 (open access)

CO2 SELECTIVE CERAMIC MEMBRANE FOR WATER-GAS SHIFT REACTION WITH CONCOMITANT RECOVERY OF CO2

Two process schemes have been investigated by us for the use of hydrotalcites we prepared as CO{sub 2} adsorbents to enhance water gas shift (WGS) reaction: Case I involves the adsorption enhanced WGS packed bed reactor and Case II involves the adsorption enhanced WGS membrane reactor. Both cases will achieve the same objective as the hydrotalcite membrane reactor: i.e., improving the WGS reactor efficiency via the concomitant removal of CO{sub 2} for sequestration. In this report a detailed investigation of the design characteristics and performance of Case II, termed the Hybrid Adsorbent-Membrane Reactor (HAMR), is presented. The HAMR system includes a packed-bed catalytic membrane reactor (hydrogen selective) coupling the WGS reaction (in a porous hydrogen selective membrane) with CO{sub 2} removal with an adsorbent in the permeate side. The reactor characteristics have been investigated for a range of permeance and selectivity relevant to the aforementioned application. The HAMR system shows enhanced CO conversion, hydrogen yield, and product purity, and provides good promise for reducing the hostile operating conditions of conventional WGS reactors, and for meeting the CO{sub 2} sequestration objective. In the next quarterly report we will present the simulation result for Case I as well as the progress on …
Date: February 19, 2004
Creator: Liu, Paul K. T.
Object Type: Report
System: The UNT Digital Library
A Comprehensive Study of Surface Chemistry for Application to Engine NOx Aftertreatment (open access)

A Comprehensive Study of Surface Chemistry for Application to Engine NOx Aftertreatment

This work focuses on developing a scientific understanding of the processes associated with NO{sub x} trap operation. NO{sub x} traps are the most advanced technology for achieving future emissions standards with diesel engines. Successful development of NO{sub x} traps will allow widespread use of diesel engines in light-duty vehicles, reducing oil imports by as much as 60%. Diesel engines have a high efficiency and low maintenance that makes them the ideal choice for transportation applications. Use of diesel engines in all light-duty vehicles would reduce oil consumption in the USA by 30% and oil imports by 60%, considerably improving our energy security. For heavy trucks, there is no viable alternative to diesel engines. Only diesel engines can provide the necessary high efficiency and long life. These benefits are offset by high emission of pollutants. Diesel engines have high emissions of NO{sub x} and particulate matter. Over the last 20 years, EPA has been reducing allowable emissions from diesel engines, and NO{sub x} emissions are scheduled to be cut by a factor of 10 over the next 7 years. The target NO{sub x} emissions for year 2010 is 0.20 g/hp-hr. This value is well below 1 g/hp-hr, which has been identified …
Date: February 19, 2004
Creator: Aceves, S M; Piggot, T; Pitz, W; Mundy, C; Kuo, W & Havstad, M
Object Type: Report
System: The UNT Digital Library
Design, fabrication, and characterization of high-efficiency extreme ultraviolet diffusers (open access)

Design, fabrication, and characterization of high-efficiency extreme ultraviolet diffusers

As the development of extreme ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, makes it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such example is the diffuser often implemented with ordinary ground glass in the visible light regime. Here we demonstrate the fabrication of reflective EUV diffusers with high efficiency within a controllable bandwidth. Using these techniques we have fabricated diffusers with efficiencies exceeding 10% within a moderate angular single-sided bandwidth of approximately 0.06 radians.
Date: February 19, 2004
Creator: Naulleau, Patrick P.; Liddle, J. Alexander; Salmassi, Farhad; Anderson, Erik H. & Gullikson, Eric M.
Object Type: Article
System: The UNT Digital Library
The Dictyostelium discoideum cellulose synthase: Structure/function analysis and identification of interacting proteins (open access)

The Dictyostelium discoideum cellulose synthase: Structure/function analysis and identification of interacting proteins

OAK-B135 The major accomplishments of this project were: (1) the initial characterization of dcsA, the gene for the putative catalytic subunit of cellulose synthase in the cellular slime mold Dictyostelium discoideum; (2) the detection of a developmentally regulated event (unidentified, but perhaps a protein modification or association with a protein partner) that is required for cellulose synthase activity (i.e., the dcsA product is necessary, but not sufficient for cellulose synthesis); (3) the continued exploration of the developmental context of cellulose synthesis and DcsA; (4) the isolation of a GFP-DcsA-expressing strain (work in progress); and (5) the identification of Dictyostelium homologues for plant genes whose products play roles in cellulose biosynthesis. Although our progress was slow and many of our results negative, we did develop a number of promising avenues of investigation that can serve as the foundation for future projects.
Date: February 19, 2004
Creator: Blanton, Richard L.
Object Type: Report
System: The UNT Digital Library
Effects of the Electron Energy Distribution Function on Modeled X-ray Spectra (open access)

Effects of the Electron Energy Distribution Function on Modeled X-ray Spectra

This paper presents the results of a broad investigation into the effects of the electron energy distribution function on the predictions of non-LTE collisional-radiative atomic kinetics models. The effects of non-Maxwellian and suprathermal (''hot'') electron distributions on collisional rates (including three-body recombination) are studied. It is shown that most collisional rates are fairly insensitive to the functional form and characteristic energy of the electron distribution function as long as the characteristic energy is larger than the threshold energy for the collisional process. Collisional excitation and ionization rates, however, are highly sensitive to the fraction of hot electrons. This permits the development of robust spectroscopic diagnostics that can be used to characterize the electron density, bulk electron temperature, and hot electron fraction of plasmas with non-equilibrium electron distribution functions (EDFs). Hot electrons are shown to increase and spread out plasma charge state distributions, amplify the intensities of emission lines fed by direct collisional excitation and radiative cascades, and alter the structure of satellite features in both K- and L-shell spectra. The characteristic energy, functional form, and spatial properties of hot electron distributions in plasmas are open to characterization through their effects on high-energy continuum and line emission and on the polarization …
Date: February 19, 2004
Creator: Shlyaptseva, A S & Hansen, S B
Object Type: Article
System: The UNT Digital Library
Electroweak Symmetry Breaking via UV Insensitive Anomaly Mediation (open access)

Electroweak Symmetry Breaking via UV Insensitive Anomaly Mediation

Anomaly mediation solves the supersymmetric flavor and CP problems. This is because the superconformal anomaly dictates that supersymmetry breaking is transmitted through nearly flavor-blind infrared physics that is highly predictive and UV insensitive. Slepton mass squareds, however, are predicted to be negative. This can be solved by adding D-terms for U(1)_Y and U(1)_{B-L} while retaining the UV insensitivity. In this paper we consider electroweak symmetry breaking via UV insensitive anomaly mediation in several models. For the MSSM we find a stable vacuum when tanbeta< 1, but in this region the top Yukawa coupling blows up only slightly above the supersymmetry breaking scale. For the NMSSM, we find a stable electroweak breaking vacuum but with a chargino that is too light. Replacing the cubic singlet term in the NMSSM superpotential with a term linear in the singlet wefind a stable vacuum and viable spectrum. Most of the parameter region with correct vacua requires a large superpotential coupling, precisely what is expected in the"Fat Higgs'" model in which the superpotential is generated dynamically. We have therefore found the first viable UV complete, UV insensitive supersymmetry breaking model that solves the flavor and CP problems automatically: the Fat Higgs model with UV insensitive …
Date: February 19, 2004
Creator: Kitano, Ryuichiro; Kribs, Graham D. & Murayama, Hitoshi
Object Type: Article
System: The UNT Digital Library
Guided wave acoustic monitoring of corrosion in recovery boiler tubing (open access)

Guided wave acoustic monitoring of corrosion in recovery boiler tubing

Corrosion of tubing used in black-liquor recovery boilers is a major concern in all pulp and paper mills. Extensive corrosion in recovery boiler tubes can result in a significant safety and environmental hazard. Considerable plant resources are expended to inspect recovery boiler tubing. Currently, visual and ultrasonic inspections are primarily used during the annual maintenance shutdown to monitor corrosion rates and cracking of tubing. This Department of Energy, Office of Industrial Technologies project is developing guided acoustic waves for use on recovery boiler tubing. The feature of this acoustic technique is its cost-effectiveness in inspecting long lengths of tubes from a single inspection point. A piezoelectric or electromagnetic transducer induces guided waves into the tubes. The transducer detects fireside defects from the coldside or fireside of the tube. Cracking and thinning on recovery boiler tubes have been detected with this technique in both laboratory and field applications. This technique appears very promising for recovery boiler tube application, potentially expediting annual inspection of tube integrity.
Date: February 19, 2004
Creator: Quarry, M J & Chinn, D J
Object Type: Article
System: The UNT Digital Library
Heat Transfer Analysis for a Fixed CST Column (open access)

Heat Transfer Analysis for a Fixed CST Column

In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow condition through the column was assumed as one of the reference conditions for the simulation of a loss-of-flow accident. A series of the modeling calculations has been performed using a computational heat transfer approach. Results for the baseline model indicate that transit times to reach 130 degrees Celsius maximum temperature of the CST-salt solution column are about 96 hours when the 20-in CST column with 300 Ci/liter heat generation source and 25 degrees Celsius initial column temperature is cooled by natural convection of external air as a primary heat transfer mechanism. The modeling results for the 28-in column equipped with water jacket systems on the external wall surface of the column and water coolant pipe at the center of the CST column demonstrate that the column loaded with 300 Ci/liter heat source can be maintained non-boiling indefinitely. Sensitivity calculations for …
Date: February 19, 2004
Creator: Lee, Si Young
Object Type: Report
System: The UNT Digital Library
Imaging of Isotopically Enhanced Molecular Targeting Agents Final Report (open access)

Imaging of Isotopically Enhanced Molecular Targeting Agents Final Report

The goal of this project is to develop experimental and computational protocols to use SIMS to image the chemical composition of biological samples, focusing on optimizing sample preparation protocols and developing multivariate data analysis methods. Our results on sample preparation, molecular imaging, and multivariate analysis have been presented at several meeting abstracts (UCRL151797ABS, UCRL151797ABSREV1, UCRL151426ABS, UCRL201277, UCRL154757). A refereed paper describing our results for sample preparation and molecular imaging of various endogenous biomolecules as well as the mutagen PhIP has been accepted for publication (UCRL-JC-151797). We are also preparing two additional papers describing our multivariate analysis methods to analyze spectral data. As these papers have not been submitted, their content is included in this final report.
Date: February 19, 2004
Creator: Quong, J N
Object Type: Report
System: The UNT Digital Library
Impact of a Revised Convective Triggering Mechanism on CAM2 Model Simulations: Results from Short-Range Weather Forecasts (open access)

Impact of a Revised Convective Triggering Mechanism on CAM2 Model Simulations: Results from Short-Range Weather Forecasts

This study implements a revised convective triggering condition in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM2) model to reduce its excessive warm season daytime precipitation over land. The new triggering mechanism introduces a simple dynamic constraint on the initiation of convection that emulates the collective effects of lower level moistening and upward motion of the large-scale circulation. It requires a positive contribution from the large-scale advection of temperature and moisture to the existing positive Convective Available Potential Energy (CAPE) for model convection to start. In contrast, the original convection triggering function in CAM2 assumes that convection is triggered whenever there is positive CAPE, which results in too frequent warm season convection over land arising from strong diurnal variation of solar radiation. We examine the impact of the new trigger on CAM2 simulations by running the climate model in Numerical Weather Prediction (NWP) mode so that more available observations and high-frequency NWP analysis data can be used to evaluate model performance. We show that the modified triggering mechanism has led to considerable improvements in the simulation of precipitation, temperature, moisture, clouds, radiations, surface temperature, and surface sensible and latent heat fluxes when compared to the data collected …
Date: February 19, 2004
Creator: Xie, S; Boyle, J S; Cederwall, R T; Potter, G L; Zhang, M & Lin, W
Object Type: Article
System: The UNT Digital Library
Microwave Imaging Reflectometry for the Measurement of Turbulent Fluctuations in Tokamaks (open access)

Microwave Imaging Reflectometry for the Measurement of Turbulent Fluctuations in Tokamaks

This article describes a numerical study of microwave reflectometry for the measurement of turbulent fluctuations in tokamak-like plasmas with a cylindrical geometry. Similarly to what was found previously in plane-stratified plasmas, the results indicate that the characteristics of density fluctuations cannot be uniquely determined from the reflected waves if the latter are allowed to propagate freely to the point of detection, as in standard reflectometry. Again, we find that if the amplitude of fluctuations is below a threshold that is set by the spectrum of poloidal wave numbers, the local characteristics of density fluctuations can be obtained from the phase of reflected waves when these are collected with a wide aperture antenna, and an image of the cutoff is formed onto an array of phase-sensitive detectors.
Date: February 19, 2004
Creator: Mazzucato, E.
Object Type: Report
System: The UNT Digital Library
Observation of Fluorine-Vacancy Complexes in Silicon (open access)

Observation of Fluorine-Vacancy Complexes in Silicon

We show direct evidence, obtained by positron annihilation spectroscopy, for the complexing of fluorine with vacancies in silicon. Both float zone and Czochralski silicon wafers were implanted with 30 keV fluorine ions to a fluence of 2x10{sup 14} ions/cm{sup 2}, and studied in the as-implanted condition, and after annealing to 650o C for 10 and for 30 minutes. The ''2-detector'' background reduction technique for positron annihilation was applied. The spectra reveal a significant concentration of fluorine-vacancy complexes after annealing, for both Czochralski and float zone material, supporting the results of computer simulations of the implantation and annealing process.
Date: February 19, 2004
Creator: Jenei, Z.; Simpson, P. J.; Robison, R. R.; Asoka-Kumar, P. & Law, M. E.
Object Type: Article
System: The UNT Digital Library
PRELIMINARY FIELD EVALUATION OF MERCURY CONTROL USING COMBUSTION MODIFICATIONS (open access)

PRELIMINARY FIELD EVALUATION OF MERCURY CONTROL USING COMBUSTION MODIFICATIONS

In this project General Electric Energy and Environmental Research Corporation conducts a preliminary field evaluation of a novel technology, referred to as Hg/NO{sub x}, that can reduce emissions of both mercury (Hg) and oxides of nitrogen (NO{sub x}) from coal-fired power plants. The evaluation takes place in Green Station Unit 2 operated by Western Kentucky Energy. Reduction of Hg and NO{sub x} emissions in Unit 2 is achieved using coal reburning. Activities during first project year (January 23, 2003--January 22, 2004) included measurements of baseline Hg emissions in Unit 2 and pilot-scale testing. Baseline testing of Hg emissions in Green Unit 2 has been completed. Two fuels were tested with OFA system operating at minimum air flow. Mercury emissions were measured at ESP inlet and outlet, and at the stack using Ontario Hydro revised method. Testing demonstrated that baseline Hg reductions at ESP outlet and stack were 30-45% and 70-80%, respectively. Pilot-scale testing demonstrated good agreement with baseline measurements in Unit 2. Testing showed that fuel composition had an effect on the efficiency of Hg absorption on fly ash. Maximum achieved Hg removal in reburning was close to 90%. Maximum achieved Hg reduction at air staging conditions was 60%. Testing …
Date: February 19, 2004
Creator: Lissianski, Vitali & Marquez, Antonio
Object Type: Report
System: The UNT Digital Library
Quantifying human vitamin kinetics using AMS (open access)

Quantifying human vitamin kinetics using AMS

Tracing vitamin kinetics at physiologic concentrations has been hampered by a lack of quantitative sensitivity for chemically equivalent tracers that could be used safely in healthy people. Instead, elderly or ill volunteers were sought for studies involving pharmacologic doses with radioisotopic labels. These studies fail to be relevant in two ways: vitamins are inherently micronutrients, whose biochemical paths are saturated and distorted by pharmacological doses; and while vitamins remain important for health in the elderly or ill, their greatest effects may be in preventing slow and cumulative diseases by proper consumption throughout youth and adulthood. Neither the target dose nor the target population are available for nutrient metabolic studies through decay counting of radioisotopes at high levels. Stable isotopic labels are quantified by isotope ratio mass spectrometry at levels that trace physiologic vitamin doses, but the natural background of stable isotopes severely limits the time span over which the tracer is distinguishable. Indeed, study periods seldom ranged over a single biological mean life of the labeled nutrients, failing to provide data on the important final elimination phase of the compound. Kinetic data for the absorption phase is similarly rare in micronutrient research because the phase is rapid, requiring many consecutive …
Date: February 19, 2004
Creator: Hillegonds, Darren; Dueker, Stephen R.; Ognibene, Ted; Buchholz, Bruce A.; Lin, Yumei; Vogel, John S. et al.
Object Type: Article
System: The UNT Digital Library
A Report on the use of Weak-Shock Wave Profiles and 3-D Dislocation Dynamics Simulations for Validation of Dislocation Multiplication and Mobility in the Phonon Drag Regime (open access)

A Report on the use of Weak-Shock Wave Profiles and 3-D Dislocation Dynamics Simulations for Validation of Dislocation Multiplication and Mobility in the Phonon Drag Regime

Dynamically loaded gas gun experiments were performed to validate the predictive capabilities of 3-D dislocation dynamics (DD) code simulations at very high strain rates and dislocation velocities where the phonon drag mechanism will be dominant. Experiments were performed in the weak-shock regime on high-purity Mo single crystals with [001] compression axes. We have also performed shock-recovery experiments and are in the process of analyzing the dislocation structure generated by the weak-shock using transmission electron microscopy (TEM), which will also be used to validate the dislocation structure predicted by the DD simulations. The DD simulations being performed at Washington State University by Prof. H. Zbib and co-workers will be compared to the experimentally measured wave profiles, thereby validating mechanisms of dislocation generation and motion. Some DD simulation results are presented to demonstrate the feasibility of using a combined experimental/simulation effort for the validation of dislocation generation and mobility physics issues in the phonon drag regime.
Date: February 19, 2004
Creator: Cazamias, J; Lassila, D; Shehadeh, M & Zbib, H
Object Type: Report
System: The UNT Digital Library
Status of Neutrino Factory R&D within the Muon Collaboration (open access)

Status of Neutrino Factory R&D within the Muon Collaboration

The authors describe the current status of the research within the Muon Collaboration towards realizing a Neutrino Factory. The authors describe briefly the physics motivation behind the neutrino factory approach to studying neutrino oscillations and the longer term goal of building the Muon Collider. The benefits of a step by step staged approach of building a proton driver, collecting and cooling muons followed by the acceleration and storage of cooled muons are emphasized. Several usages of cooled muons open up at each new stage in such an approach and new physics opportunities are realized at the completion of each stage.
Date: February 19, 2004
Creator: Raja, Rajendran
Object Type: Article
System: The UNT Digital Library
Strontium Isotopes in Pore Water as an Indicator of Water Flux at the Proposed High-Level Radioactive Waste Repository, Yucca Mountain, Nevada (open access)

Strontium Isotopes in Pore Water as an Indicator of Water Flux at the Proposed High-Level Radioactive Waste Repository, Yucca Mountain, Nevada

The proposed high-level radioactive waste repository at Yucca Mountain, Nevada, would be constructed in the high-silica rhyolite (Tptp) member of the Miocene-age Topopah Spring Tuff, a mostly welded ash-flow tuff in the {approx}500-m-thick unsaturated zone. Strontium isotope compositions have been measured in pore water centrifuged from preserved core samples and in leachates of pore-water salts from dried core samples, both from boreholes in the Tptp. Strontium isotope ratios ({sup 87}Sr/{sup 86}Sr) vary systematically with depth in the surface-based boreholes. Ratios in pore water near the surface (0.7114 to 0.7124) reflect the range of ratios in soil carbonate (0.7112 to 0.7125) collected near the boreholes, but ratios in the Tptp (0.7122 to 0.7127) at depths of 150 to 370 m have a narrower range and are more radiogenic due to interaction with the volcanic rocks (primarily non-welded tuffs) above the Tptp. An advection-reaction model relates the rate of strontium dissolution from the rocks with flow velocity. The model results agree with the low transport velocity ({approx}2 cm per year) calculated from carbon-14 data by I.C. Yang (2002, App. Geochem., v. 17, no. 6, p. 807-817). Strontium isotope ratios in pore water from Tptp samples from horizontal boreholes collared in tunnels at …
Date: February 19, 2004
Creator: Marshall, B. & Futa, K.
Object Type: Report
System: The UNT Digital Library
Theoretical treatment of double photoionization of helium using a B-spline implementation of exterior complex scaling (open access)

Theoretical treatment of double photoionization of helium using a B-spline implementation of exterior complex scaling

Calculations of absolute triple differential and single differential cross sections for helium double photoionization are performed using an implementation of exterior complex scaling in B-splines. Results for cross sections, well-converged in partial waves, are presented and compared with both experiment and earlier theoretical calculations. These calculations establish the practicality and effectiveness of the complex B-spline approach to calculations of double ionization of atomic and molecular systems.
Date: February 19, 2004
Creator: McCurdy, C. William; Horner, Daniel A.; Rescigno, Thomas N. & Martin, Fernando
Object Type: Article
System: The UNT Digital Library
VISION Model : description of model used to estimate the impact of highway vehicle technologies and fuels on energy use and carbon emissions to 2050. (open access)

VISION Model : description of model used to estimate the impact of highway vehicle technologies and fuels on energy use and carbon emissions to 2050.

The VISION model has been developed by the U.S. Department of Energy (DOE) to provide estimates of the potential energy use, oil use, and carbon emission impacts to 2050 of advanced light- and heavy-duty highway vehicle technologies and alternative fuels. DOE supports research of advanced transportation technologies (including fuels) and is frequently asked to provide estimates of the potential impacts of successful market penetration of these technologies, sometimes on a relatively quick-turnaround basis. VISION is a spreadsheet model in Microsoft Excel that can be used to respond rapidly to quick-turnaround requests, as well as for longer-term analyses. It uses vehicle survival and age-dependent usage characteristics to project total light and heavy vehicle stock, total vehicle miles of travel (VMT), and total energy use by technology and fuel type by year, given market penetration and vehicle energy efficiency assumptions developed exogenously. Total carbon emissions for on-highway vehicles by year are also estimated because life-cycle carbon coefficients for various fuels are included in VISION. VISION is not a substitute for the transportation component of the Energy Information Administration's (EIA's) National Energy Modeling System (NEMS). NEMS incorporates a consumer choice model to project market penetration of advanced vehicles and alternative fuels. The projections …
Date: February 19, 2004
Creator: Singh, M.; Vyas, A. & Steiner, E.
Object Type: Report
System: The UNT Digital Library