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Non-Markovian Nonstationary Completely Positive Open-Quantum-System Dynamics (open access)

Non-Markovian Nonstationary Completely Positive Open-Quantum-System Dynamics

This article discusses non-Markovian nonstationary completely positive open-quantum-system dynamics.
Date: August 4, 2009
Creator: Budini, Adrián A. & Grigolini, Paolo
System: The UNT Digital Library
Jahn - Teller Distortion in the Phosphorescent Excited State of Three-Coordinate Au(I) Phosphine Complexes (open access)

Jahn - Teller Distortion in the Phosphorescent Excited State of Three-Coordinate Au(I) Phosphine Complexes

This article discusses three-coordinate Au(I) phosphine complexes.
Date: November 4, 2003
Creator: Barakat, Khaldoon A.; Cundari, Thomas R., 1964- & Omary, Mohammad A.
System: The UNT Digital Library
Bonding and Structure of Copper Nitrenes (open access)

Bonding and Structure of Copper Nitrenes

Article discussing research on the bonding and structure of copper nitrenes.
Date: October 4, 2008
Creator: Cundari, Thomas R., 1964- & Dinescu, Adriana
System: The UNT Digital Library
Combined Experimental and Computational Study of TpRu{P(pyr)3} (NCMe)Me (pyr = N-pyrrolyl): Inter- and Intramolecular Activation of C-H Bonds and the Impact of Sterics on Catalytic Hydroarylation of Olefins (open access)

Combined Experimental and Computational Study of TpRu{P(pyr)3} (NCMe)Me (pyr = N-pyrrolyl): Inter- and Intramolecular Activation of C-H Bonds and the Impact of Sterics on Catalytic Hydroarylation of Olefins

This article discusses a combined experimental and computational study of TpRu{P(pyr)3} (NCMe)Me (pyr = N-pyrrolyl).
Date: October 4, 2007
Creator: Foley, Nicholas A.; Lail, Marty; Gunnoe, T. Brent; Cundari, Thomas R., 1964-; Boyle, Paul D. & Petersen, Jeffrey L.
System: The UNT Digital Library
Genetic analysis of the spindle checkpoint genes san-I, mdf-2, bub-3 and the CENP-F homologues hcp-1 and hcp-2 in Caenorhabditis elegans (open access)

Genetic analysis of the spindle checkpoint genes san-I, mdf-2, bub-3 and the CENP-F homologues hcp-1 and hcp-2 in Caenorhabditis elegans

Article on a genetic analysis of the spindle checkpoint genes san-I, mdf-2, bub-3 and the CENP-F homologues hcp-1 and hcp-2 in Caenorhabditis elegans.
Date: February 4, 2008
Creator: Hajeri, Vinita A.; Stewart, Anil M.; Moore, Landon L. & Padilla, Pamela A.
System: The UNT Digital Library
Renewal and memory properties in the random growth of surfaces (open access)

Renewal and memory properties in the random growth of surfaces

Article discussing the renewal and memory properties in the random growth of surfaces.
Date: February 4, 2008
Creator: Cakir, Rasit; Grigolini, Paolo & Ignaccolo, Massimiliano
System: The UNT Digital Library
Comment on "Systematic Investigation of the Sorption Properties of Polyurethane Foams for Organic Vapors" (open access)

Comment on "Systematic Investigation of the Sorption Properties of Polyurethane Foams for Organic Vapors"

This article gives a comment to a previous article entitled "Systematic investigation of the sorption properties of polyurethane foams for organic vapors."
Date: August 4, 2007
Creator: Sprunger, Laura M.; Acree, William E. (William Eugene) & Abraham, M. H. (Michael H.)
System: The UNT Digital Library
Effectiveness of a Community Health Worker as Sole Diabetes Educator: Comparison of CoDE with Similar Culturally Appropriate Interventions (open access)

Effectiveness of a Community Health Worker as Sole Diabetes Educator: Comparison of CoDE with Similar Culturally Appropriate Interventions

Article discussing the effectiveness of a community health worker as sole diabetes educator.
Date: November 4, 2008
Creator: Culica, Dan; Walton, James W.; Harker, Karen & Prezio, Elizabeth A.
System: The UNT Digital Library
Solubility of Clonazepam, Diazepam, Lamotrigine, and Phenobarbital in N-Methyl-2-pyrrolidone + Water Mixtures at 298.2 K (open access)

Solubility of Clonazepam, Diazepam, Lamotrigine, and Phenobarbital in N-Methyl-2-pyrrolidone + Water Mixtures at 298.2 K

Article on the solubility of clonazepam, diazepam, lamotrigine, and phenobarbital in N-methyl-2-pyrrolidone + water mixtures at 298.2 K.
Date: June 4, 2009
Creator: Shayanfar, Ali; Acree, William E. (William Eugene) & Jouyban, Abolghasem
System: The UNT Digital Library
Initial Evidence for Self-Organized Criticality in Electric Power System Blackouts (open access)

Initial Evidence for Self-Organized Criticality in Electric Power System Blackouts

We examine correlations in a time series of electric power system blackout sizes using scaled window variance analysis and R/S statistics. The data shows some evidence of long time correlations and has Hurst exponent near 0.7. Large blackouts tend to correlate with further large blackouts after a long time interval. Similar effects are also observed in many other complex systems exhibiting self-organized criticality. We discuss this initial evidence and possible explanations for self-organized criticality in power systems blackouts. Self-organized criticality, if fully confirmed in power systems, would suggest new approaches to understanding and possibly controlling blackouts.
Date: January 4, 2000
Creator: Carreras, B. A.; Dobson, I.; Newman, D. E. & Poole, A. B.
System: The UNT Digital Library
Monte Carlo simulation of ferroelectric domain structure: Electrostatic and elastic strain energy contributions (open access)

Monte Carlo simulation of ferroelectric domain structure: Electrostatic and elastic strain energy contributions

A lattice-Monte Carlo approach was developed to simulate ferroelectric domain behavior. The model utilizes a Hamiltonian for the total energy that includes electrostatic terms (involving dipole-dipole interactions, local polarization gradients, and applied electric field), and elastic strain energy. The contributions of these energy components to the domain structure and to the overall applied field response of the system were examined. In general, the model exhibited domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. Good qualitative agreement between the appearance of simulated electrical hysteresis loops and those characteristic of real ferroelectric materials was found.
Date: April 4, 2000
Creator: Potter, Barrett G., Jr.; Tuttle, Bruce A. & Tikare, Veena
System: The UNT Digital Library
Effect of firing conditions on thick film microstructure and solder joint strength for low-temperature, co-fired ceramic substrates (open access)

Effect of firing conditions on thick film microstructure and solder joint strength for low-temperature, co-fired ceramic substrates

Low-temperature, co-fired ceramics (LTCC) are the substrate material-of-choice for a growing number of multi-chip module (MCM) applications. Unlike the longer-standing hybrid microcircuit technology based upon alumina substrates, the manufacturability and reliability of thick film solder joints on LTCC substrates have not been widely studied. An investigation was undertaken to fully characterize solder joints on these substrates. A surface mount test vehicle with Daisy chain electrical connections was designed and built with Dupont{trademark} 951 tape. The Dupont{trademark} 4569 thick film ink (Au76-Pt21-Pd3 wt.%) was used to establish the surface conductor pattern. The conductor pattern was fired onto the LTCC substrate in a matrix of processing conditions that included: (1) double versus triple prints, (2) dielectric window versus no window, and (3) three firing temperatures (800 C, 875 C and 950 C). Sn63-Pb37 solder paste with an RMA flux was screen printed onto the circuit boards. The appropriate packages, which included five sizes of chip capacitors and four sizes of leadless ceramic chip carriers, were placed on the circuit boards. The test vehicles were oven reflowed under a N{sub 2} atmosphere. Nonsoldered pads were removed from the test vehicles and the porosity of their thick film layers was measured using quantitative image …
Date: January 4, 2000
Creator: Hernandez, C. L.; Vianco, P. T. & Rejent, J. A.
System: The UNT Digital Library
Targeting refrigerators for repair or replacement. (open access)

Targeting refrigerators for repair or replacement.

Refrigerator energy use is a dominant component of total energy use for many low-income households. Poorly operating or inefficient refrigerators can place an unnecessary financial burden on those households or the public agencies that pay their electricity bills, such as housing authorities. This paper presents an analytic tool that is low cost and easy to use. The procedure can be implemented with minimal staff training. The tool enables housing providers or weatherization agencies to identify poorly operating or high use refrigerators and target them for replacement or repair. The use of the procedure is illustrated, and its value for participants in a bulk refrigerator purchase and replacement program is discussed.
Date: April 4, 2000
Creator: Cavallo, J. & Mapp, J.
System: The UNT Digital Library
System description: IVY (open access)

System description: IVY

IVY is a verified theorem prover for first-order logic with equality. It is coded in ACL2, and it makes calls to the theorem prover Otter to search for proofs and to the program MACE to search for countermodels. Verifications of Otter and MACE are not practical because they are coded in C. Instead, Otter and MACE give detailed proofs and models that are checked by verified ACL2 programs. In addition, the initial conversion to clause form is done by verified ACL2 code. The verification is done with respect to finite interpretations.
Date: February 4, 2000
Creator: McCune, W. & Shumsky, O.
System: The UNT Digital Library
Solventless sol-gel chemistry through ring-opening polymerization of bridged disilaoxacyclopentanes (open access)

Solventless sol-gel chemistry through ring-opening polymerization of bridged disilaoxacyclopentanes

Disilaoxacyclopentanes have proven to be excellent precursors to sol-gel type materials. These materials have shown promise as precursors for encapsulation and microelectronics applications. The polymers are highly crosslinked and are structurally similar to traditional sol-gels, but unlike typical sol-gels they are prepared without the use of solvents and water, they have low VOC's and show little shrinkage during processing.
Date: April 4, 2000
Creator: Rahimian, Kamyar & Loy, Douglas A.
System: The UNT Digital Library
On the influence of applied fields on spinel formation (open access)

On the influence of applied fields on spinel formation

Interfaces play an important role in determining the effect of electric fields on the mechanism of the formation spinel by solid-state reaction. The reaction occurs by the movement of phase boundaries but the rate of this movement can be affected by grain boundaries in the reactants or in the reaction product. Only by understanding these relationships will it be possible to engineer their behavior. As a particular example of such a study, MgIn{sub 2}O{sub 4} can be formed by the reaction between single-crystal MgO substrate and a thin film of In{sub 2}O{sub 3} with or without an applied electric field. High-resolution backscattered electron (BSE) imaging and electron backscattered diffraction (EBSD) in a scanning electron microscope (SEM) has been used to obtain complementary chemical and crystallographic information.
Date: April 4, 2000
Creator: Korte, C.; Farer, J. K.; Ravishankar, N.; Michael, Joseph R.; Schmalzried, J. & Carter, C. B.
System: The UNT Digital Library
Polymethylsilsesquioxanes Through Base-Catalyzed Redistribution of Oligomethylhydridosiloxanes (open access)

Polymethylsilsesquioxanes Through Base-Catalyzed Redistribution of Oligomethylhydridosiloxanes

There has been an increasing amount of interest in silsesquioxanes and polysilsesquioxanes. They have been used as models for silica surfaces and have been shown to have great potential for several industrial applications. Typical synthesis of polysilsesquioxanes involves the hydrolysis of organotricholorosilanes and/or organotrialkoxysilanes in the presence of acid or base catalysts, usually in the presence of organic solvents.
Date: April 4, 2000
Creator: Rahimian, Kamyar; Assink, Roger A. & Loy, Douglas A.
System: The UNT Digital Library
Unusual magnetic quantum oscillations in organic metals at high magnetic fields (open access)

Unusual magnetic quantum oscillations in organic metals at high magnetic fields

The authors report on Shubnikov-de Haas (SdH) and de Haas-van Alphen (dHvA) results for the highly two-dimensional (2D) organic superconductors {kappa}-(ET){sub 2}I{sub 3} ({Tc} = 3.5 K) and {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} ({Tc} = 4.4 K). The SdH oscillations of both materials show an apparent deviation from the well-understood 2D dHvA signal at low temperatures and high magnetic fields. For {kappa}-(ET){sub 2}I{sub 3}, the mechanism leading to this behavior still needs to be clarified. For {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3}, an anomalous steady background part of the magnetoresistance seems to account for the observed discrepancies.
Date: April 4, 2000
Creator: Wosnitza, J.; Wanka, S.; Hagel, J.; Qualls, J. S.; Brooks, J. S.; Balthes, E. et al.
System: The UNT Digital Library
Density functional theory of simple polymers in a slit pore: 3. Surface tension (open access)

Density functional theory of simple polymers in a slit pore: 3. Surface tension

In a previous study of tangent site chains near a surface, the inhomogeneous density profiles were found through Density Functional theory. In the current study, the surface tensions of these systems are found from the results of the previous study through a thermodynamic integration. The calculated surface tensions are then compared to those found directly through computer simulation. Both the surface tension and surface excess for polymeric systems are shown to qualitatively differ from those of atomic systems, although certain similarities are seen at high densities.
Date: April 4, 2000
Creator: HOOPER,JUSTIN B.; MCCOY,JOHN D.; CURRO,JOHN G. & VAN SWOL,FRANK B.
System: The UNT Digital Library
Cathodoluminescent display phosphors (open access)

Cathodoluminescent display phosphors

The past several years rendered a resurgence of interest in phosphors for low-voltage flat panel displays utilizing cathodoluminescence (CL). A major selection criterion for these phosphors is CL efficiency. The objective is to maximize the efficiency at low voltages. This work focuses on understanding the materials properties that influence CL efficiency below 1 kV. Existing high-voltage CL efficiency models take into account intrinsic materials properties such as band-gap energy. Experimental data reveals that the CL efficiency also depends on physical properties such as particle and crystallite size. An update, predictive model of CL efficiency that includes the effects of crystallite size, radiative recombination probability, and electron accelerating potential was developed. The predicted efficiencies agree very well with experimental results. The experimental data were collected using a hot filament electron gun in a demountable high-vacuum chamber. To obtain measurement accuracy, secondary electrons were collected and the phosphor excited with a uniform beam profile. A CL characterization protocol for display phosphors was established at Sandia National Laboratories and made available to phosphor researchers.
Date: January 4, 2000
Creator: Shea, L.E.
System: The UNT Digital Library
Control of the RF waveform at the chuck of an industrial oxide-etch reactor (open access)

Control of the RF waveform at the chuck of an industrial oxide-etch reactor

Radio frequency (rf) power is applied to the chuck of a high-density plasma reactor in order to extract ions and to control the energy of the ions used for the fabrication of microelectronic devices. In many cases, the temporal shape of the rf waveform largely determines the shape of the spectrum of those extracted ions, thereby strongly affecting feature evolution. Using auxiliary rf circuits the authors successfully made major changes to the rf potential waveform at the chuck of an Applied Materials 5300 HDP Omega reactor without affecting the normal functioning of the reactor's control systems. This work established the practical feasibility of techniques for modifying the ion energy distribution functions of industrial reactors.
Date: May 4, 2000
Creator: Berry, Lee; Maynard, Helen; Miller, Paul A.; Moore, Tony; Pendley, Michael; Resta, Victoria et al.
System: The UNT Digital Library
DC characteristics of OMVPE-grown N-p-n InGaP/InGaAsN DHBTs (open access)

DC characteristics of OMVPE-grown N-p-n InGaP/InGaAsN DHBTs

The authors demonstrate, for the first time, a functional N-p-n heterojunction bipolar transistor using a novel material, InGaAsN, with a bandgap energy of 1.2eV as the p-type base layer. A 300{angstrom}-thick In{sub x}Ga{sub 1-x}As graded layer was introduced to reduce the conduction band offset at the p-type InGaAsN base and n-type GaAs collector junction. For an emitter size of 500 {mu}m{sup 2}, a peak current gain of 5.3 has been achieved.
Date: January 4, 2000
Creator: Li, N. Y.; Chang, P. C.; Baca, A. G.; Xie, X. M.; Sharps, P. R. & Hou, H. Q.
System: The UNT Digital Library
Effect of initial seed and number of samples on simple-random and Latin-Hypercube Monte Carlo probabilities (confidence interval considerations) (open access)

Effect of initial seed and number of samples on simple-random and Latin-Hypercube Monte Carlo probabilities (confidence interval considerations)

In order to devise an algorithm for autonomously terminating Monte Carlo sampling when sufficiently small and reliable confidence intervals (CI) are achieved on calculated probabilities, the behavior of CI estimators must be characterized. This knowledge is also required in comparing the accuracy of other probability estimation techniques to Monte Carlo results. Based on 100 trials in a hypothesis test, estimated 95% CI from classical approximate CI theory are empirically examined to determine if they behave as true 95% CI over spectrums of probabilities (population proportions) ranging from 0.001 to 0.99 in a test problem. Tests are conducted for population sizes of 500 and 10,000 samples where applicable. Significant differences between true and estimated 95% CI are found to occur at probabilities between 0.1 and 0.9, such that estimated 95% CI can be rejected as not being true 95% CI at less than a 40% chance of incorrect rejection. With regard to Latin Hypercube sampling (LHS), though no general theory has been verified for accurately estimating LHS CI, recent numerical experiments on the test problem have found LHS to be conservatively over an order of magnitude more efficient than SRS for similar sized CI on probabilities ranging between 0.25 and 0.75. …
Date: May 4, 2000
Creator: ROMERO,VICENTE J.
System: The UNT Digital Library
Performance Assessment Analyses Unique to Department of Energy Spent Nuclear Fuel (open access)

Performance Assessment Analyses Unique to Department of Energy Spent Nuclear Fuel

This paper describes the iterative process of grouping and performance assessment that has led to the current grouping of the U.S. Department of Energy (DOE) spent nuclear fuel (SNF). The unique sensitivity analyses that form the basis for incorporating DOE fuel into the total system performance assessment (TSPA) base case model are described. In addition, the chemistry that results from dissolution of DOE fuel and high level waste (HLW) glass in a failed co-disposal package, and the effects of disposal of selected DOE SNF in high integrity cans are presented.
Date: June 4, 2000
Creator: Loo, H. H. & Duguid, J. O.
System: The UNT Digital Library