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Generalized b-spline subdivision-surface wavelets and lossless compression (open access)

Generalized b-spline subdivision-surface wavelets and lossless compression

We present a new construction of wavelets on arbitrary two-manifold topology for geometry compression. The constructed wavelets generalize symmetric tensor product wavelets with associated B-spline scaling functions to irregular polygonal base mesh domains. The wavelets and scaling functions are tensor products almost everywhere, except in the neighborhoods of some extraordinary points (points of valence unequal four) in the base mesh that defines the topology. The compression of arbitrary polygonal meshes representing isosurfaces of scalar-valued trivariate functions is a primary application. The main contribution of this paper is the generalization of lifted symmetric tensor product B-spline wavelets to two-manifold geometries. Surfaces composed of B-spline patches can easily be converted to this scheme. We present a lossless compression method for geometries with or without associated functions like color, texture, or normals. The new wavelet transform is highly efficient and can represent surfaces at any level of resolution with high degrees of continuity, except at a finite number of extraordinary points in the base mesh. In the neighborhoods of these points detail can be added to the surface to approximate any degree of continuity.
Date: November 24, 1999
Creator: Bertram, M; Duchaineau, M A; Hamann, B & Joy, K I
System: The UNT Digital Library
X-Ray Absorption Characterization of Diesel Exhaust Particulates (open access)

X-Ray Absorption Characterization of Diesel Exhaust Particulates

We have characterized particulates from a 1993 11.1 Detroit Diesel Series 60 engine with electronic unit injectors operated using fuels with and without methylcyclopentadienyl manganese tricarbonyl (MMT) and overbased calcium sulfonate added. X-ray photoabsorption (XAS) spectroscopy was used to characterize the diesel particulates. Results reveal a mixture of primarily Mn-phosphate with some Mn-oxide, and Ca-sulfate on the surface of the filtered particulates from the diesel engine.
Date: November 18, 1999
Creator: Nelson, A J; Ferreira, J L; Reynolds, J G & Roos, J W
System: The UNT Digital Library
Denoising of human speech using combined acoustic and em sensor signal processing (open access)

Denoising of human speech using combined acoustic and em sensor signal processing

Low Power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference. This greatly enhances the quality and quantify of information for many speech related applications. See Holzrichter, Burnett, Ng, and Lea, J. Acoustic. Soc. Am. 103 (1) 622 (1998). By using combined Glottal-EM- Sensor- and Acoustic-signals, segments of voiced, unvoiced, and no-speech can be reliably defined. Real-time Denoising filters can be constructed to remove noise from the user's corresponding speech signal.
Date: November 29, 1999
Creator: Ng, L C; Burnett, G C; Holzrichter, J F & Gable, T J
System: The UNT Digital Library
Radiation Transport in Type IA Supernovae (open access)

Radiation Transport in Type IA Supernovae

It has been said more than once that the critical link between explosion models and observations is the ability to accurately simulate cooling and radiation transport in the expanding ejecta of Type Ia supernovae. It is perhaps frustrating to some of the theorists who study explosion mechanisms, and to some of the observers too, that more definitive conclusions have not been reached about the agreement, or lack thereof, between various Type Ia supernova models and the data. Although claims of superlative accuracy in transport simulations are sometimes made, I will argue here that there are outstanding issues of critical importance and in need of addressing before radiation transport calculations are accurate enough to discriminate between subtly different explosion models.
Date: November 16, 1999
Creator: Eastman, R
System: The UNT Digital Library
Diode-Pumped Solid-State Lasers for Internal Fusion Energy (open access)

Diode-Pumped Solid-State Lasers for Internal Fusion Energy

We have begun building the ''Mercury'' laser system as the first in a series of new generation diode-pumped solid-state lasers for inertial fusion research. Mercury will integrate three key technologies: diodes, crystals, and gas cooling, within a unique laser architecture that is scalable to kilojoule and megajoule energy levels for fusion energy applications. The primary near-term performance goals include 10% electrical efficiencies at 10 Hz and 100J with a 2-10 ns pulse length at 1.047 mm wavelength. When completed, Mercury will allow rep-rated target experiments with multiple chambers for high energy density physics research.
Date: November 15, 1999
Creator: Payne, S. A.; Bibeau, C.; Beach, R. J.; Bayramian, A.; Chanteloup, J. C.; Ebbers, C. A. et al.
System: The UNT Digital Library
EUV emission-line spectrum of OY carinae in superoutburst: scattering in the wind (open access)

EUV emission-line spectrum of OY carinae in superoutburst: scattering in the wind

The ''Extreme Ultraviolet Explorer'' satellite observed the cataclysmic variable OY Carinae in superoutburst for 3 days in March 1997. The resulting 80-180 {angstrom} spectrum, which contains broad (FWHM {approx} 2000 km s{sup -1}) emission lines of O V-VI, Ne V-VI, Mg V-VI, and Fe VI-VIII, is well modeled by scattering of boundary layer radiation in the system's accretion disk wind.
Date: November 21, 1999
Creator: Mauche, C W & Raymond, J C
System: The UNT Digital Library
Stellar Opacity (open access)

Stellar Opacity

The monochromatic opacity, {kappa}{sub v}, quantifies the property of a material to remove energy of frequency v from a radiation field. A harmonic average of {kappa}{sub v}, known as the Rosseland mean, {kappa}{sub R}, is frequently used to simplify the calculation of energy transport in stars. The term ''opacity'' is commonly understood to refer to {kappa}{sub R}. Opacity plays an important role in stellar modeling because for most stars radiation is the primary mechanism for transporting energy from the nuclear burning region in the core to the surface. Depending on the mass, convection and electron thermal conduction can also be important modes of stellar energy transport. The efficiency of energy transport is related to the temperature gradient, which is directly proportional to the mean radiative opacity in radiation dominated regions. When the radiative opacity is large, convection can become the more efficient energy transport mechanism. Electron conductive opacity, the resistance of matter to thermal conduction, is inversely proportional to electron thermal conductivity. Thermal conduction becomes the dominant mode of energy transport at high density and low temperature.
Date: November 7, 1999
Creator: Rogers, F J & Iglesias, C A
System: The UNT Digital Library
Computer simulation of the effect of copper on defect production and damage evolution in ferritic steels (open access)

Computer simulation of the effect of copper on defect production and damage evolution in ferritic steels

It has long been noticed that the effect of Cu solute atoms is important for the microstructural evolution of ferritic pressure vessel steels under neutron irradiation conditions. Despite the low concentration of Cu in steel, Cu precipitates form inside the a-Fe surrounding matrix and by impeding free dislocation motion considerably contribute to the hardening of the material. It has been suggested that Cu-rich clusters and combined Cu solute atoms-defect clusters that may act as initiating structures of further precipitates nucleate during annealing of displacement cascades. In order to assess the importance of the different mechanisms taking place during collision events in the formation and later evolution of these structures, a detailed Molecular Dynamics (MD) analysis of displacement cascades in a Fe-1.3% at. Cu binary alloy has been carried out. Cascade energies ranging from 1 to 20 keV have been simulated at temperatures of 100 and 600 K using the MDCASK code, in which the Ackland-Finnis-Sinclair many-body interatomic potential has been implemented. The behavior of metastable Cu self-interstitial atoms (SIAs) in the form of mixed Fe-Cu features is studied as well as their impact on the resulting defect structures. It is observed that above 300 K generated Cu SIAs undergo recombination …
Date: November 28, 1999
Creator: Perlado, J. M; Marian, J.; Lodi, D. & Diaz de la Rubia, T.
System: The UNT Digital Library
Very intense pulse in the groundwater flow in fissurized-porous stratum (open access)

Very intense pulse in the groundwater flow in fissurized-porous stratum

None
Date: November 1, 1999
Creator: Barenblatt, G.I.; Ingerman, E.A.; Shvets, H. & Vazquez, J.L.
System: The UNT Digital Library
Safety Analyses at the Idaho National Engineering and Environmental Laboratory Test Reactor Area - Past to Present (open access)

Safety Analyses at the Idaho National Engineering and Environmental Laboratory Test Reactor Area - Past to Present

Test reactors are unique in that the core configuration may change with each operating interval. The process of safety analyses for test reactors at the Idaho National Engineering and Environmental Test Reactor Area has evolved as the computing capabilities, software, and regulatory requirements have changed. The evaluations for experiments and the reactor have moved from measurements in a set configuration and then application to other configurations with a relatively large error to modeling in three-dimensions and explicit analyses for each experiment and operating interval. This evolution is briefly discussed for the Test Reactor Area.
Date: November 1, 1999
Creator: Ambrosek, Richard Garry & Ingram, Frederick William
System: The UNT Digital Library
Department of Energy - Field Operations Program (open access)

Department of Energy - Field Operations Program

The Field Operations Program is an advanced-technology alternative fuel vehicle testing and evaluation program sponsored by the U.S. Department of Energy’s (DOE’s) Office of Technology Utilization. This Office is located within the Office of Transportation Technologies. The Program evaluates advanced-technology alternative fuel vehicles in real-world applications and environments, focusing on commercially viable vehicles that represent the “leading edge” in on-road transportation technologies. In the near-term, this includes hybrid electric vehicles and pure electric vehicles with advanced energy storage systems. In the long-term, this may include advanced natural gas vehicles, fuel cell vehicles utilizing a variety of fuels, and vehicles powered by advanced combinations of hybrid technologies.
Date: November 1, 1999
Creator: Francfort, James Edward
System: The UNT Digital Library
Critical Temperatures and Pressures for Hydrocarbon Mixtures Froman Equation of State With Renormalization-Group-Theory Corrections (open access)

Critical Temperatures and Pressures for Hydrocarbon Mixtures Froman Equation of State With Renormalization-Group-Theory Corrections

A recently developed crossover equation of state incorporates contributions from long-wavelength density fluctuations by renormalization-group theory. This equation of state can satisfactorily describes the thermodynamic properties of chain fluids both far-from and near-to the critical region; it is used here to calculate the critical locus of a mixture. Because the calculations require much computation tim, especially for ternary (any higher) mixtures, an interpolation method is used as suggested by Redlich over 30 years ago. For a binary mixture, along the critical line that gives the critical temperature of critical pressure as a function of composition, the limiting slopes at the critical slopes at the critical points of the pure components are explicitly derived from the criteria for a critical point. Logarithmic-hyperbolic interpolation equations are selected to calculate the entire critical line of the binary mixtures; this procedure is then generalized to multicomponent mixtures. Upon comparison with experimental critical lines for binary and multicomponent Type I mixtures of n-alkanes.
Date: November 1, 1999
Creator: Jiang, J. & Prausnitz, J.M.
System: The UNT Digital Library
Transport properties of the solid polymer electrolyte systemP(EO)nLiTFSI (open access)

Transport properties of the solid polymer electrolyte systemP(EO)nLiTFSI

None
Date: November 1, 1999
Creator: Edman, Ludvig; Doeff, Marca M.; Ferry, Anders; Kerr, John & DeJonghe, Lutgard C.
System: The UNT Digital Library
The Experimental Analysis of Local Heat and Mass Transfer Data for Vertical Falling Film Absorption (open access)

The Experimental Analysis of Local Heat and Mass Transfer Data for Vertical Falling Film Absorption

In pure heat transfer, specifications of effectiveness, fluid properties, and flows enable calculation of the heat exchanger area. In the case of falling film absorption, a simultaneous heat and mass transfer governs the performance of the absorber. The exchange of mass across the liquid-vapor interface involves the generation of heat. The heat effects associated with the mass exchange increase the temperature, which affects the equilibrium state of the pressure and composition and in turn affects the mass. The falling film flow rate coupled to the physical properties of kinematic viscosity and surface tension govern the flow regime of a vertical falling film. Wavy-laminar, roll-wave laminar, and turbulent flows will develop convective contributions that can enhance the transfer of mass into the film. The combined interaction of all these factors makes the absorption process very difficult to analyze and predict. A study of simultaneous heat and mass transfer was therefore conduct ed on a vertical falling film absorber to better understand the mechanisms driving the heat and mass transfer processes. Falling films are characteristically unstable, and a wavy-laminar flow was observed during the experimental study. The wavy flow further complicates the problem; therefore, only limited information is known about the temperature …
Date: November 14, 1999
Creator: Keyhani, M. & Miller, W. A.
System: The UNT Digital Library
Heating Distributions in the Target of the Spallation Neutron Source (open access)

Heating Distributions in the Target of the Spallation Neutron Source

Detailed calculation of the heat distributions in the structural parts of the target (Hg) and the target itself were made with realistic proton profiles. Preliminary current profiles of the protons coming from the accumulator ring, calculated and parameterized by the Brookhaven National Laboratory (BNL), were used as input to the Monte Carlo code LAHET. Due to limitations of the present version of the LAHET code, the real source was approximated with a nest of elliptical rings (all with the same eccentricity). The BNL's source was then fitted according to this elliptical description considering two constraints: (1) to preserve the areas of the contours of equal intensity of the real proton current density, and (2) to keep the ellipses with the same shape. In this way the best elliptical shape to describe the source was found. Because of the gaussian nature of the real current distribution, the elliptical fit is also gaussian in the elliptical coordinate.
Date: November 18, 1999
Creator: Charlton, L.A. & Difilippo, F.C.
System: The UNT Digital Library
The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption (open access)

The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption

Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for cotnfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to he one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller�s capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller. The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the …
Date: November 14, 1999
Creator: Keyhani, M. & Miller, W. A.
System: The UNT Digital Library
Neutronic Design Calculations on Moderators for the Spallation Neutron Source (SNS) (open access)

Neutronic Design Calculations on Moderators for the Spallation Neutron Source (SNS)

The Spallation Neutron Source (SNS) to be built at the Oak Ridge National Laboratory will provide an intense source of neutrons for a large variety of experiments. It consists of a high-energy (1-GeV) and high-power ({approximately}1-MW) proton accelerator, an accumulator ring, together with a target station and an experimental area. In the target itself, the proton beam will produce neutrons via the spallation process and these will be converted to low-energy (<2-eV) neutrons in moderators located close to the target. Current plans are to have two liquid-hydrogen (20-K) moderators and two room-temperature H{sub 2}O moderators. Extensive engineering design work has been conducted on the moderator vessels. For our studies we have produced realistic neutronic representations of these moderators. We report on neutronic studies conducted on these representations of the moderators using Monte Carlo simulation techniques.
Date: November 14, 1999
Creator: Murphy, D.B.
System: The UNT Digital Library
Superconducting quadrupole magnets cooling system cost estimation (open access)

Superconducting quadrupole magnets cooling system cost estimation

None
Date: November 30, 1999
Creator: Li, N.
System: The UNT Digital Library
A superconducting quadrupole array for transport of multiple high current beams (open access)

A superconducting quadrupole array for transport of multiple high current beams

We present a conceptual design of a superconducting quadrupole magnet array for the side-by-side transport of multiple high current particle beams in induction linear accelerators. The magnetic design uses a modified cosine 20 current distribution inside a square cell boundary. Each interior magnet's neighbors serve as the return flux paths and the poles are placed as close as possible to each other to facilitate this. No iron is present in the basic 2-D magnetic design; it will work at any current level without correction windings. Special 1/8th quadrupoles are used along the transverse periphery of the array to contain and channel flux back into the array, making every channel look as part of an infinite array. This design provides a fixed dimension array boundary equal to the quadrupole radius that can be used for arrays of any number of quadrupole channels, at any field level. More importantly, the design provides magnetic field separation between the array and the induction cores which may be surrounding it. Flux linkage between these two components can seriously affect the operation of both of them.
Date: November 1, 1999
Creator: Faltens, A. & Shuman, D.
System: The UNT Digital Library
Heavy ion beams for inertial confinement fusion (open access)

Heavy ion beams for inertial confinement fusion

None
Date: November 1, 1999
Creator: Lee, Edward P.
System: The UNT Digital Library
Ultrasonic characterization of synthetic soils for application to near surface geophysics (open access)

Ultrasonic characterization of synthetic soils for application to near surface geophysics

None
Date: November 11, 1999
Creator: Berge, P; Bonner, B P; Boro, C; Hardy, E; Ruddle, C & Trombino, C
System: The UNT Digital Library
Magnetic field generation from Self-Consistent collective neutrino-plasma interactions (open access)

Magnetic field generation from Self-Consistent collective neutrino-plasma interactions

A new Lagrangian formalism for self-consistent collective neutrino-plasma interactions is presented in which each neutrino species is described as a classical ideal fluid. The neutrino-plasma fluid equations are derived from a covariant relativistic variational principle in which finite-temperature effects are retained. This new formalism is then used to investigate the generation of magnetic fields and the production of magnetic helicity as a result of collective neutrino-plasma interactions.
Date: November 24, 1999
Creator: Brizard, A. J.; Murayama, H. & Wurtele, J. S.
System: The UNT Digital Library
Interactions of Uranium and Neptunium with Cementitious Materials Studied by XAFS (open access)

Interactions of Uranium and Neptunium with Cementitious Materials Studied by XAFS

We have investigated the interaction of U(VI) and Np(V) actinide ions with cementitious materials that are relevant to nuclear waste repositories using X-Ray Absorption Fine Structure (XAFS) Spectroscopy. The actinide ions were individually loaded onto untreated as well as hydrothermally treated cements. The mixtures were then equilibrated at varying pH's for a period of approximately 6 months. In all cases uranium was introduced in the form of aqueous uranyl ion, UO{sub 2}{sup 2+}, and was observed to remain in this form based on the Near Edge (XANES) spectra. The uranium samples show evidence of interactions with both treated and untreated cements at all pH's, with uranyl interacting with the cement mineral phases (i.e., SiO{sub 2}) through an inner-sphere mechanism where oxygen atoms in the equatorial plane of the uranyl ion are shared with the mineral surface. In contact with the hydrothermally treated cement, the uranyl ions are also observed to form oligomeric species, proving that hydrothermal treatment of the concrete has a significant effect on the structural bonding characteristics of uranyl on the concrete. Neptunium was introduced as the neptunyl ion, NpO{sub 2}{sup +}, and was observed to undergo a reduction from Np(V) to Np(IV). Percent reduction was calculated from …
Date: November 3, 1999
Creator: Sylwester, E. R.; Allen, P. G.; Zhao, P. & Viani, B. E.
System: The UNT Digital Library
Electronic Effects on Grain Boundary Structure in BCC Metals (open access)

Electronic Effects on Grain Boundary Structure in BCC Metals

The dominant factor in determining the atomic structure of grain boundaries is the crystal structure of the material, e.g. FCC vs. BCC. However, for a given crystal structure, the structure of grain boundaries can be influenced by electronic effects, i.e. by the element comprising the crystal. Understanding and modeling the influence of electronic structure on defect structures is a key ingredient for successful atomistic simulations of materials with more complicated crystal structures than FCC. We have found that grain boundary structure is a critical test for interatomic potentials. To that end, we have fabricated the identical {Sigma}5 (3l0)/[001] symmetric tilt grain boundary in three different BCC metals (Nb, MO, and Ta) by diffusion bonding precisely oriented single crystals. The structure of these boundaries have been determined by high resolution transmission electron microscopy. The boundaries have been found to have different atomic structures. The structures of these boundaries have been modeled with atomistic simulations using interatomic potentials incorporating angularly dependent interactions, such as those developed within Model Generalized Pseudopotential Theory. The differing structures of these boundaries can be understood in terms of the strength of the angular dependence of the interatomic interaction. We report here the results for Ta.
Date: November 15, 1999
Creator: Campbell, G. H.; King, W. E.; Belak, J. A.; Moriarty, J. A. & Foiles, S. M.
System: The UNT Digital Library