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Improving Conservation for First-Order System Least Squares Finite-Element Methods (open access)

Improving Conservation for First-Order System Least Squares Finite-Element Methods

None
Date: September 5, 2012
Creator: Adler, J H & Vassilevski, P S
System: The UNT Digital Library
Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info) (open access)

Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info)

Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.
Date: September 5, 2011
Creator: Aerosol Dynamics Inc.,; Aerodyne Research, Inc.,; Tofwerk AG, Thun, Switzerland; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H. et al.
System: The UNT Digital Library
Progress on the Europium Neutron-Capture Study using DANCE (open access)

Progress on the Europium Neutron-Capture Study using DANCE

The accurate measurement of neutron-capture cross sections of the Eu isotopes is important for many reasons including nuclear astrophysics and nuclear diagnostics. Neutron capture excitation functions of {sup 151,153}Eu targets were measured recently using a 4{pi} {gamma}-ray calorimeter array DANCE located at the Los Alamos Neutron Science Center for E{sub n} = 0.1-100 keV. The progress on the data analysis efforts is given in the present paper. The {gamma}-ray multiplicity distributions for the Eu targets and Be backing are significantly different. The {gamma}-ray multiplicity distribution is found to be the same for different neutron energies for both {sup 151}Eu and {sup 153}Eu. The statistical simulation to model the {gamma}-ray decay cascade is summarized.
Date: September 5, 2006
Creator: Agvaanluvsan, U.; Becker, J. A.; Macri, R. A.; Parker, W.; Wilk, P.; Wu, C. Y. et al.
System: The UNT Digital Library
Role of Artificial Intelligence for Analysis of COVID-19 Vaccination-Related Tweets: Opportunities, Challenges, and Future Trends (open access)

Role of Artificial Intelligence for Analysis of COVID-19 Vaccination-Related Tweets: Opportunities, Challenges, and Future Trends

Article states that vaccines, though reliable preventative measures for diseases, also raise public concerns; public apprehension and doubts challenge the acceptance of new vaccines including the COVID-19 vaccines. This study is the first attempt to review the role of AI approaches in COVID-19 vaccination-related sentiment analysis.
Date: September 5, 2022
Creator: Aljedaani, Wajdi; Saad, Eysha; Rustam, Furqan; de la Torre Díez, Isabel & Ashraf, Imran
System: The UNT Digital Library
The complete genome sequence of Staphylothermus marinus reveals differences in sulfur metabolism among heterotrophic Crenarchaeota (open access)

The complete genome sequence of Staphylothermus marinus reveals differences in sulfur metabolism among heterotrophic Crenarchaeota

Staphylothermus marinus is an anaerobic, sulfur-reducing peptide fermenter of the archaeal phylum Crenarchaeota. It is the third heterotrophic, obligate sulfur reducing crenarchaeote to be sequenced and provides an opportunity for comparative analysis of the three genomes. The 1.57 Mbp genome of the hyperthermophilic crenarchaeote Staphylothermus marinus has been completely sequenced. The main energy generating pathways likely involve 2-oxoacid:ferredoxin oxidoreductases and ADP-forming acetyl-CoA synthases. S. marinus possesses several enzymes not present in other crenarchaeotes including a sodium ion-translocating decarboxylase likely to be involved in amino acid degradation. S. marinus lacks sulfur-reducing enzymes present in the other two sulfur-reducing crenarchaeotes that have been sequenced - Thermofilum pendens and Hyperthermus butylicus. Instead it has three operons similar to the mbh and mbx operons of Pyrococcus furiosus, which may play a role in sulfur reduction and/or hydrogen production. The two marine organisms, S. marinus and H. butylicus, possess more sodium-dependent transporters than T. pendens and use symporters for potassium uptake while T. pendens uses an ATP-dependent potassium transporter. T. pendens has adapted to a nutrient-rich environment while H. butylicus is adapted to a nutrient-poor environment, and S. marinus lies between these two extremes. The three heterotrophic sulfur-reducing crenarchaeotes have adapted to their habitats, terrestrial …
Date: September 5, 2008
Creator: Anderson, iain J.; Dharmarajan, Lakshmi; Rodriguez, Jason; Hooper, Sean; Porat, Iris; Ulrich, Luke E. et al.
System: The UNT Digital Library
Measurement of the Pseudoscalar Decay Constantf_D_s Using Charm-Tagged Events in e+e- Collisions atsqrt{s}=10.58 GeV (open access)

Measurement of the Pseudoscalar Decay Constantf_D_s Using Charm-Tagged Events in e+e- Collisions atsqrt{s}=10.58 GeV

Using 230.2 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector at and near the peak of the {Upsilon}(4S) resonance, 489 {+-} 55 events containing the pure leptonic decay D{sub s}{sup +} {yields} {mu}{sup +}{nu}{sub {mu}} have been isolated in charm-tagged events. The ratio of partial widths {Lambda}(D{sub s}{sup +} {yields} {mu}{sup +}{nu}{sub {mu}})/{Lambda}(D{sub s}{sup +} {yields} {phi}{pi}{sup +}) is measured to be 0.143 {+-} 0.018 {+-} 0.006 allowing a determination of the pseudoscalar decay constant f{sub D{sub 2}} = (283 {+-} 17 {+-} 7 {+-} 14) MeV. The errors are statistical, systematic, and from the D{sub s}{sup +} {yields} {phi}{pi}{sup +} branching ratio, respectively.
Date: September 5, 2006
Creator: Aubert, B.
System: The UNT Digital Library
Re-architecting TEIMS Web-based Legacy Applications Using the Model View Controller Paradigm (open access)

Re-architecting TEIMS Web-based Legacy Applications Using the Model View Controller Paradigm

None
Date: September 5, 2012
Creator: Barbosa, E & Laguna, G W
System: The UNT Digital Library
Novel Six-Quark Hidden-Color Dibaryon States in QCD (open access)

Novel Six-Quark Hidden-Color Dibaryon States in QCD

None
Date: September 5, 2013
Creator: Bashkanov, M.; Brodsky, S.J. & Clement, H.
System: The UNT Digital Library
Parental stressor exposure simultaneously conveys both adaptive and maladaptive larval phenotypes through epigenetic inheritance in the zebrafish (Danio rerio) (open access)

Parental stressor exposure simultaneously conveys both adaptive and maladaptive larval phenotypes through epigenetic inheritance in the zebrafish (Danio rerio)

This article is a study using crude oil as an example of an environmental stressor in adult zebrafish. The offspring obtained were then assessed for transgenerational epigenetic transfer of oil-induced phenotypes. The authors conclude that epigenetic transgenerational inheritance can lead to an immediate and simultaneous inheritance of both beneficial and maladaptive traits in a large proportion of the F1 larvae. The adaptive responses may help fish populations survive when facing transient environmental stressors.
Date: September 5, 2019
Creator: Bautista, Naim M. & Burggren, Warren W.
System: The UNT Digital Library
The representation of numbers by states in quantum mechanics. (open access)

The representation of numbers by states in quantum mechanics.

None
Date: September 5, 2000
Creator: Benioff, P.
System: The UNT Digital Library
Field balancing in the real world (open access)

Field balancing in the real world

Field balancing can achieve significant results when other problems are present in the frequency spectrum and multiple vibrations are evident in the waveform. Many references suggest eliminating other problems before attempting to balance. That`s great - if you can do it. There are valid reasons for this approach, and it would be much easier to balance machinery when other problems have been corrected. It is the theoretical ideal in field balancing. However, in the real world of machinery maintained for years by reacting to immediate problems, the classic vibration signature for unbalance is rarely seen. Maintenance personnel make most of their decisions with limited information. The decision to balance or not to balance is usually made the same way. This paper will demonstrate significant results of field balancing in the presence of multiple problems. By examining the data available and analyzing the probabilities, a reasonable chance for success can be assured.
Date: September 5, 1997
Creator: Bracher, B.
System: The UNT Digital Library
A Photon Free Method to Solve Radiation Transport Equations (open access)

A Photon Free Method to Solve Radiation Transport Equations

The multi-group discrete-ordinate equations of radiation transfer is solved for the first time by Newton's method. It is a photon free method because the photon variables are eliminated from the radiation equations to yield a N{sub group}XN{sub direction} smaller but equivalent system of equations. The smaller set of equations can be solved more efficiently than the original set of equations. Newton's method is more stable than the Semi-implicit Linear method currently used by conventional radiation codes.
Date: September 5, 2006
Creator: Chang, B.
System: The UNT Digital Library
Laboratory measurements of high-n iron L-shell x-ray lines (open access)

Laboratory measurements of high-n iron L-shell x-ray lines

We present a comprehensive wavelength survey of Fe L-shell X-ray lines between 7 and 11 {angstrom} measured using flat crystal spectrometers and the EBIT-I and EBIT-II electron beam ion traps at the Lawrence Livermore National Laboratory. This survey includes all significant emission lines produced by over 200 n {yields} 2 transitions in Fe XIX-XXIV, with n = 4-10. The identification and assignment of transitions are made with the help of detailed theoretical modeling using the Flexible Atomic Code (FAC).
Date: September 5, 2006
Creator: Chen, H; Gu, M F; Behar, E; Brown, G V; Kahn, S M & Beiersdorfer, P
System: The UNT Digital Library
Practical path planning among movable obstacles (open access)

Practical path planning among movable obstacles

Path planning among movable obstacles is a practical problem that is in need of a solution. In this paper an efficient heuristic algorithm that uses a generate-and-test paradigm: a good'' candidate path is hypothesized by a global planner and subsequently verified by a local planner. In the process of formalizing the problem, we also present a technique for modeling object interactions through contact. Our algorithm has been tested on a variety of examples, and was able to generate solutions within 10 seconds. 5 figs., 27 refs.
Date: September 5, 1990
Creator: Chen, Pang C. & Hwang, Yong K.
System: The UNT Digital Library
Theory Issues for Induced Plasma Convection Experiments in the Divertor of the MAST Spherical Tokamak (open access)

Theory Issues for Induced Plasma Convection Experiments in the Divertor of the MAST Spherical Tokamak

This paper surveys theory issues associated with inducing convective cells through divertor tile biasing in a tokamak to broaden the scrape-off layer (SOL). The theory is applied to the Mega-Ampere Spherical Tokamak (MAST), where such experiments are planned in the near future. Criteria are presented for achieving strong broadening and for exciting shear-flow turbulence in the SOL; these criteria are shown to be attainable in practice. It is also shown that the magnetic shear present in the vicinity of the X-point is likely to confine the potential perturbations to the divertor region below the X-point, leaving the part of the SOL that is in direct contact with the core plasma intact. The current created by the biasing and the associated heating power are found to be modest.
Date: September 5, 2001
Creator: Cohen, R. H.; Fielding, S.; Helander, P. & Ryutov, D. D.
System: The UNT Digital Library
Review of Operation and Maintenance Experience in the DOE-EPRI Wind Turbine Verification Program (open access)

Review of Operation and Maintenance Experience in the DOE-EPRI Wind Turbine Verification Program

All the projects within the US Department of Energy (DOE) Electrical Power Research Institute (EPRI) Wind Turbine Verification Program (TVP) are now in operation. As a result, the emphasis of the owners and operators has shifted from installation and commissioning to a focus on optimizing the operation and maintenance (O and M) activities of the projects. Each project utilizes a unique strategy for performing O and M. O and M personnel for projects in Searsburg, Vermont; Glenmore, Wisconsin; Algona, Iowa; Springview, Nebraska; Kotzebue, Alaska; and Big Spring, Texas include on-site vendor representatives, dedicated utility personnel, and utility personnel who split their time between the wind turbines and other utility responsibilities. Each project has its own set of priorities for balancing turbine availability against safety, minimizing overtime pay, and other utility responsibilities. Various strategies have also been employed to ensure access to tools and spare parts. This paper compares and contrasts the various O and M strategies at TVP projects and reviews the causes of turbine downtime and the frequency and duration of faults.
Date: September 5, 2000
Creator: Conover, K.; VandenBosche, J.; Rhoads, H. (Global Energy Concepts, LLC) & Smith, B. (National Renewable Energy Laboratory)
System: The UNT Digital Library
Catalytic Tuning of a Phosphinoethane Ligand for Enhanced C-H Activation (open access)

Catalytic Tuning of a Phosphinoethane Ligand for Enhanced C-H Activation

Article discussing research on the catalytic tuning of a phosphinoethane ligand for enhanced C-H activation.
Date: September 5, 2008
Creator: Cundari, Thomas R., 1964-; Jimenez-Halla, J. Oscar C.; Morello, Glenn R. & Vaddadi, Sridhar
System: The UNT Digital Library
All Fiber Technology for High-Energy Petawatt Front End Laser Systems (open access)

All Fiber Technology for High-Energy Petawatt Front End Laser Systems

We are developing an all fiber front end for the next generation high-energy petawatt (HEPW) laser at Lawrence Livermore National Laboratory (LLNL). The ultimate goal of the LLNL HEPW effort is to generate 5-kJ pulses capable of compression to 5ps at 1053nm, enabling advanced x-ray backlighters and possible demonstration of fast ignition. We discuss the front-end of the laser design from the fiber master oscillator, which generates the mode-locked 20nm bandwidth initial pulses through the 10mJ output of the large flattened mode (LFM) fiber amplifier. Development of an all fiber front end requires technological breakthroughs in the key areas of the master oscillator and fiber amplification. Chirped pulse amplification in optical fibers has been demonstrated to 1mJ. Further increase is limited by the onset of stimulated Raman scattering (SRS). We have recently demonstrated a new flattened mode fiber technology, which reduces peak power for a given energy and thus the onset of SRS. Controlled experiments with 1st generation fibers yielded 0.5mJ of energy while significantly increasing the point at which nonlinear optical effects degrade the amplified pulse. In this paper we will discuss our efforts to extend this work to greater than 20mJ using our large flattened mode fiber amplifier.
Date: September 5, 2003
Creator: Dawson, J W; Liao, Z M; Jovanovic, I; Wattellier, B; Beach, R; Payne, S A et al.
System: The UNT Digital Library
Theoretical/numerical investigation of induction cavity impedances for moderate to large gap widths (open access)

Theoretical/numerical investigation of induction cavity impedances for moderate to large gap widths

In order to understand the coupling of a charged particle beam to modes in induction cells with gap width -- to -- beampipe radius ratio w/b > 1, the variation of the transverse Z/Q for both axially symmetric and axially asymmetric dipole modes in this regime is investigated. It is found that the gross behavior of the axially symmetric modes when w/b > 1 is at least consistent with the approximate analysis of Briggs, although a thorough comparison has not been undertaken. The axially asymmetric modes are found to be unimportant until w/b approaches 2, and they generally exhibit lower values of Z{perpendicular}/Q than the axially symmetric modes.
Date: September 5, 1990
Creator: DeFord, J. F.
System: The UNT Digital Library
Application of Linear Magnetic Loss Model of Ferrite to Induction Cavity Simulation (open access)

Application of Linear Magnetic Loss Model of Ferrite to Induction Cavity Simulation

A linear, frequency independent model of the rf properties of unbiased, soft ferrite has been implemented in finite-difference, time-domain, electromagnetic simulation code AMOS for the purposes of studying linac induction cavities. The simple model consists of adding a magnetic conductivity term ({sigma}{sub m}H) to Faraday's Law. The value of {sigma}{sub m} that is appropriate for a given ferrite at a particular frequency is obtained via an rf reflection experiment on a very thin ferrite toroid in a shorted coaxial line. It was found that in the frequency range 100 to 1000 MHz, the required value of {sigma}{sub m} varies only slightly (<10%), and so we approximated it as a frequency independent parameter in AMOS. A description of the experimental setup and the technique used to extract the complex {mu} from the measurements is described. The model has been used to study the impedances of the DARHT induction cavity, and comparisons between these experimental measurements and AMOS calculations is presented. Implementation of a frequency dependent version of this model in AMOS is being pursued, and a discussion of this effort is given.
Date: September 5, 1990
Creator: DeFord, J. F. & Kamin, G.
System: The UNT Digital Library
Geographic Distance, Contact, and Family Perceptions of Quality Nursing Home Care (open access)

Geographic Distance, Contact, and Family Perceptions of Quality Nursing Home Care

Article on the geographic distance, contact and family perceptions of quality nursing home care.
Date: September 5, 2011
Creator: Dillman, Jennifer L.; Yeatts, Dale E., 1952- & Cready, Cynthia M.
System: The UNT Digital Library
Duals of Tirilman spaces have unique subsymmetric basic sequences (open access)

Duals of Tirilman spaces have unique subsymmetric basic sequences

Article describes how the Tirilman spaces were introduced by Casazza and Shura as variations of the spaces constructed by Tzafriri. We prove that all subsymmetric basic sequences in the dual space are equivalent to its canonical subsymmetic but not symmetric basis.
Date: September 5, 2023
Creator: Dilworth, Steven J.; Kutzarova, Denka; Sari, Bünyamin & Stankov, Svetozar
System: The UNT Digital Library
High-Average Power Facilities (open access)

High-Average Power Facilities

There has been significant progress in the development of high-power facilities in recent years yet major challenges remain. The task of WG4 was to identify which facilities were capable of addressing the outstanding R&amp;D issues presently preventing high-power operation. To this end, information from each of the facilities represented at the workshop was tabulated and the results are presented herein. A brief description of the major challenges is given, but the detailed elaboration can be found in the other three working group summaries.
Date: September 5, 2012
Creator: Dowell, David H. & Power, John G.
System: The UNT Digital Library
Environmental application of stable xenon and radioxenonmonitoring (open access)

Environmental application of stable xenon and radioxenonmonitoring

Characterization of transuranic waste is needed to makedecisions about waste site remediation. Soil-gas sampling for xenonisotopes can be used to define the locations of spent fuel andtransuranic wastes. Radioxenon in the subsurface is characteristic oftransuranic waste and can be measured with extreme sensitivity usinglarge-volume soilgas samples. Measurements at the Hanford Site showed133Xe and 135Xe levels indicative of 240Pu spontaneous fission. Stablexenon isotopic ratios from fission are distinct from atmospheric xenonbackground. Neutron capture by 135Xe produces an excess of 136Xe inreactor-produced xenon providing a means of distinguishing spent fuelfrom separated transuranic materials.
Date: September 5, 2006
Creator: Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre,Justin I.; Waichler, Scott R.; Milbrath, Brian D. et al.
System: The UNT Digital Library