An Iterative Phase-Space Explicit Discontinuous Galerkin Method for Stellar Radiative Transfer in Extended Atmospheres (open access)

An Iterative Phase-Space Explicit Discontinuous Galerkin Method for Stellar Radiative Transfer in Extended Atmospheres

A phase-space discontinuous Galerkin (PSDG) method is presented for the solution of stellar radiative transfer problems. It allows for greater adaptivity than competing methods without sacrificing generality. The method is extensively tested on a spherically symmetric, static, inverse-power-law scattering atmosphere. Results for different sizes of atmospheres and intensities of scattering agreed with asymptotic values. The exponentially decaying behavior of the radiative field in the diffusive-transparent transition region and the forward peaking behavior at the surface of extended atmospheres were accurately captured. The integrodifferential equation of radiation transfer is solved iteratively by alternating between the radiative pressure equation and the original equation with the integral term treated as an energy density source term. In each iteration, the equations are solved via an explicit, flux-conserving, discontinuous Galerkin method. Finite elements are ordered in wave fronts perpendicularly to the characteristic curves so that elemental linear algebraic systems are solved quickly by sweeping the phase space element by element. Two implementations of a diffusive boundary condition at the origin are demonstrated wherein the finite discontinuity in the radiative intensity is accurately captured by the proposed method. This allows for a consistent mechanism to preserve photon luminosity. The method was proved to be robust and …
Date: January 28, 2004
Creator: de Almeida, V.F.
Object Type: Report
System: The UNT Digital Library
An Evaluation of Three Commercially Available Technologies For Real-Time Measurement of Rates of Outdoor Airflow Into HVAC Systems (open access)

An Evaluation of Three Commercially Available Technologies For Real-Time Measurement of Rates of Outdoor Airflow Into HVAC Systems

During the last few years, new technologies have been introduced for real-time continuous measurement of the flow rates of outdoor air (OA) into HVAC systems; however, an evaluation of these measurements technologies has not previously been published. This document describes a test system and protocols developed for a controlled evaluation of these measurement technologies. The results of tests of three commercially available measurement technologies are also summarized. The test system and protocol were judged practical and very useful. The three commercially available measurement technologies should provide reasonably, e.g., 20%, accurate measurements of OA flow rates as long as air velocities are maintained high enough to produce accurately measurable pressure signals. In HVAC systems with economizer controls, to maintain the required air velocities the OA intake will need to be divided into two sections in parallel, each with a separate OA damper. All of the measurement devices had pressure drops that are likely to be judged acceptable. The influence of wind on the accuracy of these measurement technologies still needs to be evaluated.
Date: October 28, 2004
Creator: Fisk, William J.; Faulkner, David & Sullivan, Douglas P.
Object Type: Article
System: The UNT Digital Library
Power Systems Development Facility Gasification Test Campaing TC14 (open access)

Power Systems Development Facility Gasification Test Campaing TC14

In support of technology development to utilize coal for efficient, affordable, and environmentally clean power generation, the Power Systems Development Facility (PSDF) located in Wilsonville, Alabama, routinely demonstrates gasification technologies using various types of coals. The PSDF is an engineering scale demonstration of key features of advanced coal-fired power systems, including a KBR Transport Gasifier, a hot gas particulate control device (PCD), advanced syngas cleanup systems, and high pressure solids handling systems. This report details test campaign TC14 of the PSDF gasification process. TC14 began on February 16, 2004, and lasted until February 28, 2004, accumulating 214 hours of operation using Powder River Basin (PRB) subbituminous coal. The gasifier operating temperatures varied from 1760 to 1810 F at pressures from 188 to 212 psig during steady air blown operations and approximately 160 psig during oxygen blown operations.
Date: February 28, 2004
Creator: Southern Company Services
Object Type: Report
System: The UNT Digital Library
Report on Toyota/Prius Motor Design and Manufacturing Assessment (open access)

Report on Toyota/Prius Motor Design and Manufacturing Assessment

In today's hybrid vehicle market the Toyota Prius drive system is currently considered the leader in electrical, mechanical, and manufacturing innovations. It is significant that in today's marketplace Toyota is able to manufacture and sell the vehicle for a profit. This project's objective is to analyze and study the Prius drive system to understand the design and manufacturing mechanisms Toyota utilized to achieved their performance and cost goals. During the course of this research effort ORNL has dissected both the 2003 and 2004 Toyota/Prius drive motors. This study is focused primarily on motor design considerations and an assessment of manufacturing issues.
Date: July 28, 2004
Creator: Hsu, J.S.
Object Type: Report
System: The UNT Digital Library
Mass by Energy Loss Quantitation as a Practical Sub-Microgram Balance (open access)

Mass by Energy Loss Quantitation as a Practical Sub-Microgram Balance

A simple device integrating a thin film support and a standard microcentrifuge tube can be used for making solutions of accurately known concentration of any organic compound in a single step, avoiding serial dilution and the use of microgram balances. Nanogram to microgram quantities of organic material deposited on the thin film are quantified by ion energy loss and transferred to the microcentrifuge tube with high recovery.
Date: September 28, 2004
Creator: Palmblad, M; Bench, G & Vogel, J S
Object Type: Article
System: The UNT Digital Library
Level densities and gamma-ray strength functions in 170,171,172-Yb (open access)

Level densities and gamma-ray strength functions in 170,171,172-Yb

Level densities and radiative strength functions in {sup 171}Yb and {sup 170}Yb nuclei have been measured using the {sup 171}Yb({sup 3}He{sup 3}He{gamma}){sup 171}Yb and {sup 171}Yb({sup 3}He,{alpha}{gamma}){sup 170}Yb reactions. New data on {sup 171}Yb are compared to a previous measurement for {sup 171}Yb from the {sup 172}Yb({sup 3}He,{alpha}{gamma}){sup 171}Yb reaction. Systematics of level densities and radiative strength functions in {sup 170,171,172}Yb are established. The entropy excess in {sup 171}Yb relative to the even-even nuclei {sup 170,172}Yb due to the unpaired neutron quasiparticle is found to be approximately 2k{sub B}. Results for the radiative strength function from the two reactions lead to consistent parameters characterizing the ''pygmy'' resonances. Pygmy resonances in the {sup 170,172}Yb populated by the ({sup 3}He,{alpha}) reaction appear to be split into two components for both of which a complete set of resonance parameters are obtained.
Date: July 28, 2004
Creator: Agvaanluvsan, U.; Schiller, A.; Becker, J.; Bernstein, L.; Garrett, P.; Guttormsen, M. et al.
Object Type: Report
System: The UNT Digital Library
Flor-Essence? Herbal Tonic Promotes Mammary Tumor Development in Sprague Dawley Rats (open access)

Flor-Essence? Herbal Tonic Promotes Mammary Tumor Development in Sprague Dawley Rats

Background: Women who are diagnosed with breast cancer often self-administer complementary and alternative medicines to augment their conventional treatments, improve health, or prevent recurrence. Flor-Essence{reg_sign} Tonic is a complex mixture of herbal extracts used by cancer patients because of anecdotal evidence that it can treat or prevent disease. Methods: Female Sprague Dawley rats were given water or exposed to 3% or 6% Flor-Essence{reg_sign} beginning at one day of age. Mammary tumors were induced with a single oral 40 mg/kg/bw dose of dimethylbenz(a)anthracene at 50 days of age and sacrificed at 23 weeks. Rats were maintained on AIN-76A diet. Results: Control rats had palpable mammary tumor incidence of 51.0% at 19 weeks of age compared to 65.0% and 59.4% for the 3% and 6% Flor-Essence{reg_sign} groups respectively. Overall, no significant difference in time until first palpable tumor was detected among any of the groups. At necropsy, mammary tumor incidence was 82.5% for controls compared to 90.0% and 97.3% for rats consuming 3% and 6% Flor-Essence{reg_sign}, respectively. Mean mammary tumor multiplicity ({+-}SES) for the controls was 2.8 ({+-} 0.5) and statistically different from the 3% or 6% Flor- Essence{reg_sign} groups with 5.2 ({+-} 0.7), and 4.8 ({+-} 0.6), respectively (p{<=}0.01). As expected, …
Date: January 28, 2004
Creator: Bennett, L; Montgomery, J; Steinberg, S & Kulp, K
Object Type: Article
System: The UNT Digital Library
Calculation of Radiative Corrections to E1 matrix elements in the Neutral Alkalis (open access)

Calculation of Radiative Corrections to E1 matrix elements in the Neutral Alkalis

Radiative corrections to E1 matrix elements for ns-np transitions in the alkali metal atoms lithium through francium are evaluated. They are found to be small for the lighter alkalis but significantly larger for the heavier alkalis, and in the case of cesium much larger than the experimental accuracy. The relation of the matrix element calculation to a recent decay rate calculation for hydrogenic ions is discussed, and application of the method to parity nonconservation in cesium is described.
Date: September 28, 2004
Creator: Sapirstein, J & Cheng, K T
Object Type: Article
System: The UNT Digital Library
Techniques for Judging Intent Behind Network Based Cyber Attacks (open access)

Techniques for Judging Intent Behind Network Based Cyber Attacks

This project developed a prototype system that can rapidly differentiate between undirected cyber attacks, and those that have a more specific and concerning intent behind them. The system responds to important cyber attacks in a tactically significant way as the attack is proceeding. It is also creates a prioritized list for the human analysts allowing them to focus on the threats mostly likely to be of interest. In the recent years the volume of attacks over the internet has increased exponentially, as they have become more and more automated. The result of this is that real threats are harder and harder to distinguish from the general threat. It is possible with our current systems to identify network packets that originated from thousands of IP addresses as probing a site like LLNL in a single day. Human analysis of these threats does not result in information that can be used for tactical response because most of the attacks are short and over before the human starts the analysis. Only a very small percentage of attacks can even be evaluated manually due to the volume. This project developed methods, and prototyped tools, that can identify attacks, slow the attack down and aid …
Date: January 28, 2004
Creator: Allen, J M
Object Type: Report
System: The UNT Digital Library
NIF HEPW 2D Radiography Option Survey (open access)

NIF HEPW 2D Radiography Option Survey

None
Date: April 28, 2004
Creator: Koch, J
Object Type: Report
System: The UNT Digital Library
Accurate wavelength measurements and modeling of FeXV to FeXIX spectra recorded in high density plasmas between 13.5 to 17 A. (open access)

Accurate wavelength measurements and modeling of FeXV to FeXIX spectra recorded in high density plasmas between 13.5 to 17 A.

Iron spectra have been recorded from plasmas created at three different laser plasma facilities, the Tor Vergata University laser in Rome (Italy), the Hercules laser at ENEA in Frascati (Italy), and the Compact Multipulse Terawatt (COMET) laser at LLNL in California (USA). The measurements provide a means of identifying dielectronic satellite lines from FeXVI and FeXV in the vicinity of the strong 2p {yields} 3d transitions of FeXVII. About 80 {Delta}n {ge} 1 lines of FeXV (Mg-like) to FeXIX (O-like) were recorded between 13.8 to 17.1 {angstrom} with a high spectral resolution ({lambda}/{Delta}{lambda} {approx} 4000), about thirty of these lines are from FeXVI and FeXV. The laser produced plasmas had electron temperatures between 100 to 500 eV and electron densities between 10{sup 20} to 10{sup 22} cm{sup -3}. The Hebrew University Lawrence Livermore Atomic Code (HULLAC) was used to calculate the atomic structure and atomic rates for FeXV to FeXIX. HULLAC was used to calculate synthetic line intensities at T{sub e} = 200 eV and n{sub e} = 10{sup 21}cm{sup -3} for three different conditions to illustrate the role of opacity: optically thin plasmas with no excitation-autoionization/dielectronic recombination (EA/DR) contributions to the line intensities, optically thin plasmas that included EA/DR …
Date: September 28, 2004
Creator: May, M.; Beiersdorfer, P.; Dunn, J.; Jordan, N.; Osterheld, A.; Faenov, A. et al.
Object Type: Article
System: The UNT Digital Library
Neutron Skyshine Considerations For The NIF Shielding Design (open access)

Neutron Skyshine Considerations For The NIF Shielding Design

A series of coupled neutron-photon transport Monte-Carlo calculations was performed to estimate the roof shielding required to limit the skyshine dose to less than 1 mrem/y at the site boundary when conducting DT experiments with annual fusion yields up to 1200 MJ (4.2E20 neutrons/y). The NIF shielding design consists of many different components. The basic components include 10-cm-thick Al chamber with 40-cm-thick target chamber gunite shield having multiple penetrations, 1.83-m-thick concrete Target Bay walls, 1.37-m-thick concrete roof, and multiple concrete floors with numerous penetrations. Under this shielding configuration, the skyshine dose at the nearest site-boundary was calculated to be less than 0.2 mrem/y for all possible target illumination configurations. The potential dose at the site boundary would be about one-tenth of the cosmic neutron dose that we measured with bubble neutron detectors on board a commercial roundtrip flight from SF to Rochester. This incremental dose increase is well within the normal fluctuations (noise) of the natural background radiation in the Livermore area. The skyshine dose has no impact on the public. The skyshine dose trends at ground and elevated levels are plotted as a function of distance from 20 m to 1000 m from the center of the target bay. …
Date: January 28, 2004
Creator: Singh, M S; Mecozzi, J M & Tobin, M T
Object Type: Article
System: The UNT Digital Library
Micro-Compatibility Testing of Polysulfone (open access)

Micro-Compatibility Testing of Polysulfone

Polysulfone has many useful properties, and its compatibility with other materials is of interest. It is a tough, rigid, high-strength thermoplastic that maintains its properties over a wide temperature range. It is chemically resistant to mineral acids and alkali and moderately resistant to hydrocarbon oils; however, it is not resistant to polar organic solvents such as ketones, chlorinated hydrocarbons and aromatic hydrocarbons. Micro-compatibility experiments were initiated to determine possible detrimental interactions in a sealed environment between polysulfone components and a number of other organic species.
Date: September 28, 2004
Creator: Gregg, H; Harvey, C; Maxwell, R & Vance, A
Object Type: Report
System: The UNT Digital Library
DETERMINING CORRECT LOCATION OF INTERFACES IN X-RAY IMAGES (open access)

DETERMINING CORRECT LOCATION OF INTERFACES IN X-RAY IMAGES

X-ray phase-contrast enhanced imaging enables characterization of objects otherwise transparent to x-rays. Such imaging is accomplished with a point-source or plane-wave x-rays and in the simplest implementation takes advantage of the refraction of x-rays at interfaces to provide contrast. The refraction of x-rays, while small, can lead to measurable displacements of interfaces in the image plane. A simple approximate analytical expression is obtained for the required correction. The resulting expression is verified with a full raytrace calculation.
Date: September 28, 2004
Creator: Kozioziemski, B
Object Type: Report
System: The UNT Digital Library
A Comparison of Digital Signal Extraction Techniques (open access)

A Comparison of Digital Signal Extraction Techniques

We compare the performance of two methods of digital filtering to detect a radioactive source moving past a gamma-ray sensor. The first method is the box-car filter, which is a standard method used in the detection of a moving radioactive source. The second method is the matched filter, which takes into account the variation in the number of photons absorbed in a gamma-ray sensor as a source moves past the sensor. We optimize both methods to detect a source moving at 5, 10, 15 and 20 mph, and the receiver-operator characteristics of the two techniques are plotted for comparison. The improvement of the matched filter over the box car filter is 27% at 5 mph and 22% at 10 mph for a 90% probability of detection and an average hours between false alarms equal to 10.
Date: December 28, 2004
Creator: Cunningham, M. & Dowla, F.
Object Type: Report
System: The UNT Digital Library
Probing the Planck Scale with Proton Decay (open access)

Probing the Planck Scale with Proton Decay

We advocate the idea that proton decay may probe physics at the Planck scale instead of the GUT scale. This is possible because supersymmetric theories have dimension-5 operators that can induce proton decay at dangerous rates, even with R-parity conservation. These operators are expected to be suppressed by the same physics that explains the fermion masses and mixings. We present a thorough analysis of nucleon partial lifetimes in models with a string-inspired anomalous U(1)_X family symmetry which is responsible for the fermionic mass spectrum as well as forbidding R-parity violating interactions. Protons and neutrons can decay via R-parity conserving non-renormalizable superpotential terms that are suppressed by the Planck scale and powers of the Cabibbo angle. Many of the models naturally lead to nucleon decay near present limits without any reference to grand unification.
Date: April 28, 2004
Creator: Harnik, Roni; Larson, Daniel T.; Murayama, Hitoshi & Thormeier, Marc
Object Type: Article
System: The UNT Digital Library
Forest floor bulk density and depth at Savannah River - Draft Final Report. (open access)

Forest floor bulk density and depth at Savannah River - Draft Final Report.

Knowing the amount of biomass across a landscape is becoming increasingly important to fire managers as new fuel and fire management decision support systems come on line. Fire managers rarely have the time or funding available to sample fuels operationally and often depend upon mean values for critical variables whose variation is often associated with simple stand characteristics such as age, forest type, time since last burn, stocking, or site, and other easily measured variables. This report outlines a study to collect and analyze litter and duff bulk density samples for developing a simple predictive tool to estimate forest floor fuel loading based on simple stand characteristics.
Date: December 28, 2004
Creator: Maier, Brian; Ottmar, Roger & Wright, Clint
Object Type: Report
System: The UNT Digital Library
Laser Drilling - Drilling with the Power of Light (open access)

Laser Drilling - Drilling with the Power of Light

Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a recently acquired 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). The HPFL represents a potentially disruptive technology that, when compared to its competitors, is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. To determine how this promising laser compares with other lasers used in past experimental work, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on completion and perforation applications, although the results and techniques apply to well construction and other rock cutting applications. Variables investigated include laser power, beam intensity, external purging of cut materials, sample orientation, beam duration, beam shape, and beam frequency. The investigation also studied the …
Date: September 28, 2004
Creator: Gahan, Brian C. & Batarseh, Samih
Object Type: Report
System: The UNT Digital Library
Topical Report: Task 2.3 "Aphron Shell Hydrophobicity" (open access)

Topical Report: Task 2.3 "Aphron Shell Hydrophobicity"

Various methods were investigated to measure the oil-wetting character of transient bubbles under static and dynamic conditions, in order to determine the roles played by bubble and micellar agglomeration, coalescence and adhesion to mineral surfaces.
Date: October 28, 2004
Creator: Fosdick, Miranda & Growcock, Fred
Object Type: Report
System: The UNT Digital Library
Charge state and time resolved plasma composition of a pulsedzirconium arc in a nitrogen environment (open access)

Charge state and time resolved plasma composition of a pulsedzirconium arc in a nitrogen environment

None
Date: January 28, 2004
Creator: Rosen, Johanna; Anders, Andre; Hultman, Lars & Schneider, Jochen M.
Object Type: Article
System: The UNT Digital Library
Optical pump-probe processes in Nd 3+ doped KPb2Br5, RbPb2Br5, and KPb2CI5 (open access)

Optical pump-probe processes in Nd 3+ doped KPb2Br5, RbPb2Br5, and KPb2CI5

Recently, laser activity has been achieved in the low phonon energy, moisture-resistant bromide host crystals, neodymium-doped potassium lead bromide (Nd{sup 3+}:KPb{sub 2}Br{sub 5}) and rubidium lead bromide (Nd{sup 3+}:RbPb{sub 2}Br{sub 5}). Laser activity at 1.07 {micro}m was observed for both crystalline materials. Laser operation at the new wavelengths 1.18 {micro}m and 0.97 {micro}m resulting from the {sup 4}F{sub 5/2}+{sup 2}H{sub 9/2} {yields} {sup 4}I{sub J} transitions (J=13/2 and 11/2) in Nd:RPB was achieved for the first time in a solid state laser material. In this paper we present cw pump-probe spectra in order to discuss excited state absorption, reabsorption processes due to the long lived lower laser levels as well as possible depopulation mechanisms feasible for more efficient laser operation in these crystals. The bromides will be compared with potassium lead chloride (Nd{sup 3+}:KPb{sub 2}Cl{sub 5}).
Date: October 28, 2004
Creator: Rademaker, K; Huber, G; Payne, S A; Osiac, E & Isaenko, L I
Object Type: Article
System: The UNT Digital Library
Design and simulations of indirect drive ignition targets for NIF (open access)

Design and simulations of indirect drive ignition targets for NIF

None
Date: October 28, 2004
Creator: Haan, S. W.; Amendt, P. A.; Dittrich, T. R.; Hammel, B. A.; Hatchett, S. P.; Herrmann, M. C. et al.
Object Type: Article
System: The UNT Digital Library
Fast Ion Effects on Fishbones and n=1 Kinks in JET Simulated by a Non-perturbative NOVA-KN Code (open access)

Fast Ion Effects on Fishbones and n=1 Kinks in JET Simulated by a Non-perturbative NOVA-KN Code

New global non-perturbative hybrid code, NOVA-KN, and simulations of resonant type modes in JET [Joint European Torus] plasmas driven by energetic H-minority ions are presented. The NOVA-KN code employs the ideal-MHD description for the background plasma and treats non-perturbatively the fast particle kinetic response, which includes the fast ion finite orbit width (FOW) effect. In particular, the n = 1 fishbone mode, which is in precession drift resonance with fast ions, is studied. The NOVA-KN code is applied to model an n = 1 (f = 50-80kHz) MHD activity observed recently in JET low density plasma discharges with high fast ion (H-minority) energy content generated during the ion cyclotron resonance heating (ICRH). This n = 1 MHD activity is interpreted as the instability of the n = 1 precession drift frequency fishbone modes.
Date: October 28, 2004
Creator: Gorelenkov, N. N.; Cheng, C. Z.; Kiptily, V. G.; Mantsinen, M. J.; Sharapov, S. E. & Contributors, the JET-EFDA
Object Type: Report
System: The UNT Digital Library
Advanced ST Plasma Scenario Simulations for NSTX (open access)

Advanced ST Plasma Scenario Simulations for NSTX

Integrated scenario simulations are done for NSTX [National Spherical Torus Experiment] that address four primary milestones for developing advanced ST configurations: high {beta} and high {beta}{sub N} inductive discharges to study all aspects of ST physics in the high-beta regime; non-inductively sustained discharges for flattop times greater than the skin time to study the various current-drive techniques; non-inductively sustained discharges at high {beta} for flattop times much greater than a skin time which provides the integrated advanced ST target for NSTX; and non-solenoidal start-up and plasma current ramp-up. The simulations done here use the Tokamak Simulation Code (TSC) and are based on a discharge 109070. TRANSP analysis of the discharge provided the thermal diffusivities for electrons and ions, the neutral-beam (NB) deposition profile, and other characteristics. CURRAY is used to calculate the High Harmonic Fast Wave (HHFW) heating depositions and current drive. GENRAY/CQL3D is used to establish the heating and CD [current drive] deposition profiles for electron Bernstein waves (EBW). Analysis of the ideal-MHD stability is done with JSOLVER, BALMSC, and PEST2. The simulations indicate that the integrated advanced ST plasma is reachable, obtaining stable plasmas with {beta} {approx} 40% at {beta}{sub N}'s of 7.7-9, I{sub P} = 1.0 MA, …
Date: October 28, 2004
Creator: Kessel, C.E.; Synakowski, E.J.; Gates, D.A.; Harvey, R.W.; Kaye, S.M.; Mau, T.K. et al.
Object Type: Report
System: The UNT Digital Library