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Model studies of Rayleigh instabilities via microdesigned interfaces

Description: The energetic and kinetic properties of surfaces play a critical role in defining the microstructural changes that occur during sintering and high-temperature use of ceramics. Characterization of surface diffusion in ceramics is particularly difficult, and significant variations in reported values of surface diffusivities arise even in well-studied systems. Effects of impurities, surface energy anisotropy, and the onset of surface attachment limited kinetics (SALK) are believed to contribute to… more
Date: October 17, 2000
Creator: Glaeser, Andreas M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Double Shell Tank (DST) Monitor and Control Subsystem Definition Report

Description: The system description of the Double-Shell Tank (DST) Monitor and Control Subsystem establishes the system boundaries and describes the interface of the DST Monitor and Control Subsystem with new and existing systems that are required to accomplish the Waste Feed Delivery (WFD) mission.
Date: March 16, 2000
Creator: Bafus, Ron R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Interface Control Document Between the Double Shell Tank (DST) system and the Waste Encapsulation and Storage Facility (WESF)

Description: This Interface Control Document (ICD) describes interfaces between the Double-Shell Tanks (DST) System and Waste Encapsulation and Storage Facility (WESF) (figure 1). WESF is currently operational as a storage facility for cesium and strontium capsules. This ICD covers current operational interfaces and those envisioned during Terminal Clean Out (TCO) activities in the future. WESF and the DST System do not have a direct physical interface. The waste will be moved by tank trailer to the 204-AR … more
Date: April 19, 2000
Creator: HOFFERBER, G.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final report for grant: DE-FG02-93ER45481 [Polymers at engineered interfaces]

Description: Studies have been made of polymer interfaces, self-assembly of micelles at surfaces, phase separation in blends, diffusion and dewetting at and near interfaces, and nanomechanical properties of thin films. The main projects are summarized under the following topics: dislocations in lamellar diblock structures, effects of surface tension; compliance measurements and profiles of end-grafted polystyrene in solution observed by atomic force microscopy and neutron reflectivity; self-assembly of dibl… more
Date: January 17, 2000
Creator: Rafailovich, Miriam & Sokolov, Jonathan
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Atomic transport at liquid metal/Al{sub 2}O{sub 3} interfaces

Description: In this work, atomic force microscopy (AFM) has been used to identify the controlling transport mechanisms at metal/oxide interfaces and measure the corresponding diffusivities. Interfacial transport rates in our experiments are two to four orders of magnitude faster than any previously reported rates for the oxide surface. The interfacial diffusivities and the degree of interfacial anisotropy depend on the oxygen activity of the system. Atomic transport at metal/oxide interfaces plays a defini… more
Date: October 12, 2000
Creator: Saiz, Eduardo; Cannon, Rowland M. & Tomsia, Antoni P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Constructing Material Interfaces from Data Sets with Volume-Fraction Information

Description: We present a new algorithm for material boundary interface reconstruction from data sets containing volume fractions. We transform the reconstruction problem to a problem that analyzes the dual data set, where each vertex in the dual mesh has an associated barycentric coordinate tuple that represents the fraction of each material present. After constructing the dual tetrahedral mesh from the original mesh, we construct material boundaries by mapping a tetrahedron into barycentric space and calc… more
Date: March 29, 2000
Creator: Bonnell, K.; Duchaineau, M. A.; Schikore, D. R.; Hamann, B. & Joy, K. I.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Development of instrumentation for surface, interface and thin film science at the Advanced Photon Source. Final Technical Report for period September 15, 1994 - September 14, 2000

Description: The P.I. and his research term successfully used the funds from the DOE Instrumentation grant entitled ''Development of Instrumentation for Surface, Interface and Thin Film Science at the Advanced Photon Source'' to design, build, test, and commission a customized surface science x-ray scattering/spectroscopy chamber. This instrumentation, which is presently in use at an APS x-ray undulator beam line operated by the DuPont-Northwestern-Dow Collaborative Access Team, is used for x-ray measuremen… more
Date: September 2000
Creator: Bedzyk, Michael J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Thermomechanical Response of Layered Materials. Final technical report

Description: A new experimental technique involving instrumented indentation was demonstrated for the specific purpose of calibrating certain variations in elastic properties as a function of position in thermally sprayed and sintered materials. This work experimentally demonstrated for the first time that controlled gradients in elastic properties alone can lead to the suppression of damage and cracking during contact loading. New methods were developed in this work for the estimation of mechanical propert… more
Date: May 20, 2000
Creator: Suresh, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Characterization of oxynitride dielectric films grown in NO/O{sub 2} mixtures by rapid thermal oxynitridation

Description: Ultra-thin oxynitride films were grown on Si by direct rapid thermal processing (RTP) oxynitridation in NO/O{sub 2} ambients with NO concentrations from 5% to 50%. During oxynitridation, nitrogen accumulated at the Si/dielectric interface and the average concentration of in N through the resulting films ranged from 0.3 to 3.0 atomic percent. The average concentration of N in the films increased with increasing NO in the ambient gas, but decreased with longer RTP times. The maximum N concentrati… more
Date: February 29, 2000
Creator: Everist, Sarah C.; Meisenheimer, Timothy L.; Nelson, Gerald C. & Smith, Paul Martin
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Numerical simulation of two-phase flow with front-capturing

Description: Because of the complexity of two-phase flow phenomena, two-phase flow codes rely heavily on empirical correlations. This approach has a number of serious shortcomings. Advances in parallel computing and continuing improvements in computer speed and memory have stimulated the development of numerical simulation tools that rely less on empirical correlations and more on fundamental physics. The objective of this work is to take advantage of developments in massively parallel computing, single-pha… more
Date: February 8, 2000
Creator: Tzanos, C. P. & Weber, D. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Real-space and energy representations for the interface roughness scattering in quantum-well structures

Description: The authors show that the real space representation of the interface-roughness as a fluctuating potential in the coordinate space is equivalent to the usual energy-fluctuation representation for intrasublevel scattering in a single quantum well with a generally shaped confinement-potential profile. The coordinate picture is, however, more general and can be used for higher-order effects and multi-sublevel scattering in coupled multi-quantum-well structures.
Date: April 24, 2000
Creator: LYO,SUNGKWUN K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Investigation of self-excited induction generators for wind turbine applications

Description: The use of squirrel-cage induction machines in wind generation is widely accepted as a generator of choice. The squirrel-cage induction machine is simple, reliable, cheap, lightweight, and requires very little maintenance. Generally, the induction generator is connected to the utility at constant frequency. With a constant frequency operation, the induction generator operates at practically constant speed (small range of slip). The wind turbine operates in optimum efficiency only within a small… more
Date: February 28, 2000
Creator: Muljadi, E.; Butterfield, C.P.; Sallan, J. & Sanz, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Ultrathin aluminum oxide films: Al-sublattice structure and the effect of substrate on ad-metal adhesion

Description: First principles density-functional slab calculations are used to study 5 {angstrom} (two O-layer) Al{sub 2}O{sub 3} films on Ru(0001) and Al(111). Using larger unit cells than in a recent study, it is found that the lowest energy stable film has an even mix of tetrahedral (t) and octahedral (o) site Al ions, and thus most closely resembles the {kappa}-phase of bulk alumina. Here, alternating zig-zag rows of t and o occur within the surface plane, resulting in a greater average lateral separati… more
Date: March 6, 2000
Creator: Jennison, Dwight R. & Bogicevic, Alexander
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulation of interfacial fracture in highly crosslinked adhesives

Description: The fracture of highly-crosslinked networks is investigated by molecular dynamics simulations. The network is modeled as a bead-spring polymer network between two solid surfaces. The network is dynamically formed by crosslinking an equilibrated liquid mixture. Tensile pull fracture is simulated as a function of the number of interracial bonds. The sequence of molecular structural deformations that lead to failure are determined, and the connectivity is found to strongly control the stress-strai… more
Date: May 22, 2000
Creator: STEVENS,MARK J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Molecular-To-Continuum Fracture Analysis of Thermosetting Polymer/Solid Interfaces

Description: This report focuses on the relationship between the fundamental interactions acting across an interface and macroscopic engineering observable such as fracture toughness or fracture stress. The work encompasses experiment, theory, and simulation. The model experimental system is epoxy on polished silicon. The interfacial interactions between the substrate and the adhesive are varied continuously using self-assembling monolayer. Fracture is studied in two specimen geometries: a napkin-ring torsi… more
Date: January 1, 2000
Creator: Kent, Michael S.; Reedy, Earl David, Jr. & Stevens, Mark J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Electronic defects and interface potentials for Al oxide films on Al and their relationship to electrochemical properties

Description: The relative electronic defect densities and oxide interface potentials were determined for naturally-occurring and synthetic Al oxides on Al. In addition, the effect of electrochemical treatment on the oxide electrical properties was assessed. The measurements revealed (1) that the open circuit potential of Al in aqueous solution is inversely correlated with the oxide electronic defect density (viz., lower oxide conductivities are correlated with higher open circuit potentials), and (2) the el… more
Date: June 1, 2000
Creator: Sullivan, John P.; Dunn, Roberto G.; Barbour, J. Charles; Wall, Frederick D.; Missert, Nancy A. & Buchheit, R. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Structure within thin epoxy films revealed by solvent swelling: A neutron reflectivity study

Description: The focus of this work is the structure within highly crosslinked, two component epoxy films. The authors examine variations in crosslink density within thin epoxy films on silicon substrates by solvent swelling. The method is based on the fact that the equilibrium volume fraction of a swelling solvent is strongly dependent upon the local crosslink density. The authors examine the volume fraction profile of the good solvent nitrobenzene through the epoxy films by neutron reflection. Isotopic su… more
Date: March 2, 2000
Creator: Kent, Michael S.; Yim, Hyun; Mcnamara, William Frere; Ivkov, R.; Satija, S. & Majewski, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A DSP based power electronics interface for alternate/renewable energy systems. Quarterly report 3.

Description: This report is an update on the research project involving the implementation of a DSP based power electronics interface for alternate/renewable energy systems that was funded by the Department of Energy under the Inventions and Innovations program 1998. The objective of this research is to develop a utility interface (dc to ac converter) suitable to interconnect alternate/renewable energy sources to the utility system. The DSP based power electronics interface in comparison with existing metho… more
Date: March 31, 2000
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Interfacial structures of confined air-water two-phase bubbly flow

Description: The interfacial structure of the two-phase flows is of great importance in view of theoretical modeling and practical applications. In the present study, the focus is made on obtaining detailed local two-phase parameters in the air-water bubbly flow in a rectangular vertical duct using the double-sensor conductivity probe. The characteristic wall-peak is observed in the profiles of the interracial area concentration and the void fraction. The development of the interfacial area concentration al… more
Date: August 2000
Creator: Kim, S.; Ishii, M.; Wu, Q.; McCreary, D. & Beus, S. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Joining of alumina via copper/niobium/copper interlayers

Description: Alumina has been joined at 1150 degrees C and 1400 degrees C using multilayer copper/niobium/copper interlayers. Four-point bend strengths are sensitive to processing temperature, bonding pressure, and furnace environment (ambient oxygen partial pressure). Under optimum conditions, joints with reproducibly high room temperature strengths (approximately equal 240 plus/minus 20 MPa) can be produced; most failures occur within the ceramic. Joints made with sapphire show that during bonding an init… more
Date: March 15, 2000
Creator: Marks, Robert A.; Chapman, Daniel R.; Danielson, David T. & Glaeser, Andreas M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Reactive spreading: Adsorption, ridging and compound formation

Description: Reactive spreading, in which a chemically active element is added to promote wetting of noble metals on nonmetallic materials, is evaluated. Theories for the energetics and kinetics of the necessary steps involved in spreading are outlined and compared to the steps in compound formation that typically accompany reactive wetting. These include: fluid flow, active metal adsorption, including nonequilibrium effects, and triple line ridging. All of these can be faster than compound nucleation under… more
Date: September 11, 2000
Creator: Saiz, E.; Cannon, R. M. & Tomsia, A. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Influence of low temperature-grown GaAs on lateral thermal oxidation of Al{sub 0.98}Ga{sub 0.02}As

Description: The lateral thermal oxidation process of Al{sub 0.98}Ga{sub 0.02}As layers has been studied by transmission electron microscopy. Growing a low-temperature GaAs layer below the Al{sub 0.98}Ga{sub 0.02}As has been shown to result in better quality of the oxide/GaAs interfaces compared to reference samples. While the later have As precipitation above and below the oxide layer and roughness and voids at the oxide/GaAs interface, the structures with low-temperature have less As precipitation and dev… more
Date: June 29, 2000
Creator: Ferrer, J.C.; Liliental-Weber, Z.; Reese, H.; Chiu, Y.J. & Hu, E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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