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Resident Assistant Training: A Southwestern Perspective

Description: Article discussing a study on the similarities and differences in public and private institutions training of resident assistants in the southwest United States.
Date: December 2001
Creator: Elleven, Russell K.; Allen, Jeff M. & Sarkees-Wircenski, Michelle
Partner: UNT College of Information

Low-energy vibrations at the InSb(110) surface

Description: Article on low-energy vibrations at the InSb(110) surface along the ΓΥ direction.
Date: December 15, 1995
Creator: Buongiorno Nardelli, Marco; Cvetko, D.; De Renzi, V.; Floreano, L.; Morgante, A.; Peloi, M. et al.
Partner: UNT College of Arts and Sciences

The Evolution of Publishing Agreements at the University of Michigan

Description: Article on the evolution of publishing agreements at the University of Michigan Library. Taking as an example an open-access journal with a single editor, this article discusses the various configurations of rights agreements used by the University of Michigan Library throughout the evolution of its publishing operation, the advantages of the various models, and the reasons for moving from one to another.
Date: December 11, 2014
Creator: Hawkins, Kevin S.
Partner: UNT Libraries

Care and Health

Description: Encyclopedia article in the 'International Encyclopedia of Economic Sociology' discussing health care, globalization and health, and the effect of the economy on the structure of the health care system.
Date: December 17, 2005
Creator: Eve, Susan Brown
Partner: UNT College of Public Affairs and Community Service

Comparison of predicted far-field temperatures for discrete and smeared heat sources

Description: A fundamental concern in the design of the potential repository at Yucca Mountain. Nevada is the response of the host rock to the emplacement of heat-generating waste. The thermal perturbation of the rock mass has implications regarding the structural, hydrologic. and geochemical performance of the potential repository. The phenomenological coupling of many of these performance aspects makes repository thermal modeling a difficult task. For many of the more complex, coupled models, it is often necessary to reduce the geometry of the potential repository to a smeared heat-source approximation. Such simplifications have impacts on induced thermal profiles that in turn may influence other predicted responses through one- or two-way thermal couplings. The effect of waste employment layout on host-rock thermal was chosen as the primary emphasis of this study. Using a consistent set of modeling and input assumptions, far-field thermal response predictions made for discrete-source as well as plate source approximations of the repository geometry. Input values used in the simulations are consistent with a design-basis a real power density (APD) of 80 kW/acre as would be achieved assuming a 2010 emplacement start date, a levelized receipt schedule, and a limitation on available area as published in previous design studies. It was found that edge effects resulting from general repository layout have a significant influence on the shapes and extents of isothermal profiles, and should be accounted for in far-field modeling efforts.
Date: December 16, 1992
Creator: Ryder, E.E.
Partner: UNT Libraries Government Documents Department

Determination of coupled-lattice properties using turn-by-turn data

Description: A formalism for extracting coupled betatron parameters from multiturn, shock excited, beam position monitor data is described. The most important results are nonperturbative in that they do not rely on the underlying ideal lattice model. Except for damping, which is assumed to be exponential and small enough to be removed empirically, the description is symplectic. As well as simplifying the description, this leads to self-consistency checks that are applied to the data. The most important of these is a {open_quotes}magic ratio{close_quotes} of Fourier coefficients that is required to be a lattice invariant, the same at every beam position monitor. All formulas are applied to both real and simulated data. The real data was acquired June, 1992 at LEP as part of decoupling studies, using the LEP beam orbit measurement system. Simulated data, obtained by numerical tracking (TEAPOT) in the same (except for unknown errors) lattice, agrees well with real data when subjected to identical analysis. For both datasets, deviations between extracted and design parameters and deviations from self-consistency can be accounted for by noise and signal processing limitations. This investigation demonstrates that the LEP beam position system yields reliable local coupling measurements. It can be conservatively assumed that systems of similar design at the SSC and LHC will provide the measurements needed for local decoupling.
Date: December 1, 1992
Creator: Bourianoff, G.; Hunt, S. & Mathieson, D.
Partner: UNT Libraries Government Documents Department

Residual Stress Predictions in Polycrystalline Alumina

Description: Microstructure-level residual stresses arise in polycrystalline ceramics during processing as a result of thermal expansion anisotropy and crystallographic disorientation across the grain boundaries. Depending upon the grain size, the magnitude of these stresses can be sufficiently high to cause spontaneous microcracking during the processing of these materials. They are also likely to affect where cracks initiate and propagate under macroscopic loading. The magnitudes of residual stresses in untextured and textured alumina samples were predicted using object oriented finite (OOF) element analysis and experimentally determined grain orientations. The crystallographic orientations were obtained by electron-backscattered diffraction (EBSD). The residual stresses were lower and the stress distributions were narrower in the textured samples compared to those in the untextured samples. Crack initiation and propagation were also simulated using the Griffith fracture criterion. The grain boundary to surface energy ratios required for computations were estimated using AFM groove measurements.
Date: December 13, 1999
Partner: UNT Libraries Government Documents Department

Catastrophic failure of contaminated fused silica optics at 355 nm

Description: For years, contamination has been known to degrade the performance of optics and to sometimes initiate laser-induced damage to initiate. This study has W to quantify these effects for fused silica windows used at 355 mm Contamination particles (Al, Cu, TiO{sub 2} and ZrO{sub 2}) were artificially deposited onto the surface and damage tests were conducted with a 3 ns NdYAG laser. The damage morphology was characterized by Nomarski optical microscopy. The results showed that the damage morphology for input and output surface contamination is different. For input surface contamination, both input and output surfaces can damage. In particular, the particle can induce pitting or drilling of the surface where the beam exits. Such damage usually grows catastrophically. Output surface contamination is usually ablated away on the shot but can also induce catastrophic damage. Plasmas are observed during illumination and seem to play an important role in the damage mechanism. The relationship between fluence and contamination size for which catastrophic damage occurred was plotted for different contamination materials. The results show that particles even as small as 10 {micro}m can substantially decrease the damage threshold of the window and that metallic particles on the input surface have a more negative effect than oxide particles.
Date: December 3, 1996
Creator: Genin, F. Y., LLNL
Partner: UNT Libraries Government Documents Department

Microstructure and Performance of Kovar/Alumina Joints Made with Silver-Copper Base Active Metal Braze Alloys

Description: Poor hermeticity performance was observed for Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3} ceramic-ceramic joints having a Kovar{trademark} alloy interlayer. The active Ag-Cu-Ti filler metal was used to braze the substrates together. The Ti active element was scavenged from the filler metal by the formation of a (Fe, Ni, Co){sub x}Ti phase (x= 2-3) that prevented development of a continuous Ti{sub x}O{sub y} layer at the filler metal/Al{sub 2}O{sub 3} interface. Altering the process parameters did not circumvent the scavenging of Ti. Molybdenum barrier layers 1000, 2500, or 5000 {angstrom} thick on the Kovar{trademark} surfaces successfully allowed Ti{sub x}O{sub y} formation at the filler metal/Al{sub 2}O{sub 3} interface and hermetic joints. The problems with the Ag-Cu-Ti filler metal for Kovar{trademark}/Al{sub 2}O{sub 3} braze joints led to the evaluation of a Ag-Cu-Zr filler metal. The Zr (active element) in Ag-Cu-Zr filler metal was not susceptible to the scavenging problem.
Date: December 15, 1999
Partner: UNT Libraries Government Documents Department

Innovative vitrification for soil remediation

Description: The objective of this DOE demonstration program is to validate the performance and operation of the Vortec Cyclone Melting System (CMS{trademark}) for the processing of LLW contaminated soils found at DOE sites. This DOE vitrification demonstration project has successfully progressed through the first two phases. Phase 1 consisted of pilot scale testing with surrogate wastes and the conceptual design of a process plant operating at a generic DOE site. The objective of Phase 2, which is scheduled to be completed the end of FY 95, is to develop a definitive process plant design for the treatment of wastes at a specific DOE facility. During Phase 2, a site specific design was developed for the processing of LLW soils and muds containing TSCA organics and RCRA metal contaminants. Phase 3 will consist of a full scale demonstration at the DOE gaseous diffusion plant located in Paducah, KY. Several DOE sites were evaluated for potential application of the technology. Paducah was selected for the demonstration program because of their urgent waste remediation needs as well as their strong management and cost sharing financial support for the project. During Phase 2, the basic nitrification process design was modified to meet the specific needs of the new waste streams available at Paducah. The system design developed for Paducah has significantly enhanced the processing capabilities of the Vortec vitrification process. The overall system design now includes the capability to shred entire drums and drum packs containing mud, concrete, plastics and PCB`s as well as bulk waste materials. This enhanced processing capability will substantially expand the total DOE waste remediation applications of the technology.
Date: December 1, 1995
Creator: Jetta, N.W.; Patten, J.S. & Hart, J.G.
Partner: UNT Libraries Government Documents Department

Mechanical properties of high strength aluminum alloys formed by pulsed laser deposition

Description: Very high-strength alloys of A1(O) have been formed using a pulsed laser deposition (PLD) system to deposit from alternating targets of A1 and A1{sub 2}O{sub 3}. Ion beam analysis and transmission electron microscopy show that the deposited material is uniform in composition with up to 33 at. % O and has a highly refined microstructure consisting of a fine, uniform dispersion of {approximately}1 nm diameter {gamma}-A1{sub 2}O{sub 3} precipitates. Ultra-low-load indentation testing combined with finite-element modeling is used to determine the mechanical properties of the layers. Yield stresses as high as 5.1 GPa have been measured in these materials, greatly exceeding the strengths of aerospace Al alloys (-0.5 GPa) and even high strength steels. The key to the properties of these materials is the dispersion of small, hard precipitates spaced only a few Burgers vectors apart; dislocations are apparently unable to cut through and must bow around them.
Date: December 31, 1995
Creator: Knapp, J.A. & Follstaedt, D.M.
Partner: UNT Libraries Government Documents Department

Method of estimating maximum VOC concentration in void volume of vented waste drums using limited sampling data: Application in transuranic waste drums

Description: A test program has been conducted at the Idaho National Engineering Laboratory to demonstrate that the concentration of volatile organic compounds (VOCs) within the innermost layer of confinement in a vented waste drum can be estimated using a model incorporating diffusion and permeation transport principles as well as limited waste drum sampling data. The model consists of a series of material balance equations describing steady-state VOC transport from each distinct void volume in the drum. The primary model input is the measured drum headspace VOC concentration. Model parameters are determined or estimated based on available process knowledge. The model effectiveness in estimating VOC concentration in the headspace of the innermost layer of confinement was examined for vented waste drums containing different waste types and configurations. This paper summarizes the experimental measurements and model predictions in vented transuranic waste drums containing solidified sludges and solid waste.
Date: December 1, 1995
Creator: Liekhus, K.J. & Connolly, M.J.
Partner: UNT Libraries Government Documents Department

Progress in assessing the effect of ionizing radiation on the anticipated waste package environment at the Yucca Mountain potential repository site

Description: Progress in establishing the effect of ionizing radiation on the expected air/water vapor waste package environment is summarized. This work was performed at Argonne National Laboratory (ANL) in support of the Yucca Mountain Site Characterization Project. The radiolytic issues that have been identified are presented. Long-term gamma experiments with gas compositions ranging from dry air to high-humidity air were completed. The predominant nitrogen fixation products in all air-like systems studied were nitrogen dioxide and nitric acid. Yields between 0.8 and 2.3 molec/100 eV have been measured. Ammonia formation, although not predominant, was also observed at temperature below 100{degrees}C. The ammonia yields were low, and the concentration did not build up with increased absorbed dose. The status of the issues identified is given.
Date: December 31, 1991
Creator: Reed, D.T.
Partner: UNT Libraries Government Documents Department

Advanced materials for solid oxide fuel cells

Description: The purpose of this research is to improve the properties of the current state-of-the-art materials used for solid oxide fuel cells (SOFCs). The objectives are to: (1) develop materials based on modifications of the state-of-the-art materials; (2) minimize or eliminate stability problems in the cathode, anode, and interconnect; (3) Electrochemically evaluate (in reproducible and controlled laboratory tests) the current state-of-the-art air electrode materials and cathode/electrolyte interfacial properties; (4) Develop accelerated electrochemical test methods to evaluate the performance of SOFCs under controlled and reproducible conditions; and (5) Develop and test materials for use in low-temperature SOFCs.
Date: December 31, 1995
Creator: Armstrong, T. & Stevenson, J.
Partner: UNT Libraries Government Documents Department

The {alpha}-decay properties of {sup 181}Pb

Description: Following the production of {sup 181}Pb in {sup 92}Mo irradiations of {sup 90}Zr the isotope`s {alpha}-decay energy was measured to be 7065 (20) keV. This E{sub {alpha}} agrees with one previously published value for {sup 181}Pb but not with another.
Date: December 1995
Creator: Toth, K. S.; Batchelder, J. C. & Conticchio, L. F.
Partner: UNT Libraries Government Documents Department

Structural Modification of Sol-Gel Materials through Retro Diels-Alder Reaction

Description: Hydrolysis and condensation of organically bridged bis-triethoxysilanes, (EtO){sub 3}Si-R-Si(OEt){sub 3}, results in the formation of three dimensional organic/inorganic hybrid networks (Equation 1). Properties of these materials, including porosity, are dependent on the nature of the bridging group, R. Flexible groups (akylene-spacers longer than five carbons in length) polymerize under acidic conditions to give non-porous materials. Rigid groups (such as arylene-, alkynylene-, or alkenylene) form non-porous, microporous, and macroporous gels. In many cases the pore size distributions are quite narrow. One of the motivations for preparing hybrid organic-inorganic materials is to extend the range of properties available with sol-gel systems by incorporating organic groups into the inorganic network. For example, organically modified silica gels arc either prepared by co-polymerizing an organoalkoxysilane with a silica precursor or surface silylating the inorganic gel. This can serve to increase hydrophobicity or to introduce some reactive organic functionality. However, the type and orientation of these organic functionalities is difficult to control. Furthermore, many organoalkoxysilanes can act to inhibitor even prevent gelation, limiting the final density of organic functionalities. We have devised a new route for preparing highly functionalized pores in hybrid materials using bridging groups that are thermally converted into the desired functionalities after the gel has been obtained. In this paper, we present the preparation and characterization of bridged polysilsesquioxanes with Diels-Alder adducts as the bridging groups from the sol-gel polymerization of monomers 2 and 4. The bridging groups are constructed such that the retro Diela-Alder reaction releases the dienes and leaves the dienophiles as integral parts of the network polymers. In the rigid architecture of a xerogel, this loss of organic functionality should liberate sufficient space to modify the overall porosity. Furthermore, the new porosity will be functionalized with the dienophilic olefin bridging group. We also demonstrate that by changing the type of ...
Date: December 8, 1999
Partner: UNT Libraries Government Documents Department