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Atmospheric Radiation Measurement Program Facilities Newsletter, December 1999
Monthly newsletter discussing news and activities related to the Atmospheric Radiation Measurement Program, articles about weather and atmospheric phenomena, and other related topics.
Date:
January 17, 2000
Creator:
Atmospheric Radiation Measurement Program (U.S.)
Object Type:
Journal/Magazine/Newsletter
System:
The UNT Digital Library
Automated Mapping and Facilities Management (AM/FM) Version 8.4 Acceptance Test Report
This document provides the results of testing activities performed in order to verify that version 8.4 of the AM/FM software meets the user's requirements.
Date:
January 17, 2000
Creator:
Zakrajsek, M. F. & Mathison, Kathy M.
Object Type:
Report
System:
The UNT Digital Library
Automated Mapping and Facilities Management Version 8.4 Acceptance Test Plan
This document provides the testing process and activities to be performed in order to verify that version 8.4 of the AM/FM software meets the user's requirements.
Date:
January 17, 2000
Creator:
Zakrajsek, M. F. & Mathison, Kathy M.
Object Type:
Report
System:
The UNT Digital Library
Coupled electron-photon radiation transport
Massively-parallel computers allow detailed 3D radiation transport simulations to be performed to analyze the response of complex systems to radiation. This has been recently been demonstrated with the coupled electron-photon Monte Carlo code, ITS. To enable such calculations, the combinatorial geometry capability of ITS was improved. For greater geometrical flexibility, a version of ITS is under development that can track particles in CAD geometries. Deterministic radiation transport codes that utilize an unstructured spatial mesh are also being devised. For electron transport, the authors are investigating second-order forms of the transport equations which, when discretized, yield symmetric positive definite matrices. A novel parallelization strategy, simultaneously solving for spatial and angular unknowns, has been applied to the even- and odd-parity forms of the transport equation on a 2D unstructured spatial mesh. Another second-order form, the self-adjoint angular flux transport equation, also shows promise for electron transport.
Date:
January 17, 2000
Creator:
Lorence, L.; Kensek, R.P.; Valdez, G.D.; Drumm, C.R.; Fan, W.C. & Powell, J.L.
Object Type:
Article
System:
The UNT Digital Library
Final report for grant: DE-FG02-93ER45481 [Polymers at engineered interfaces]
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 diblock polymer micelles from solution; dewetting dynamics; polymers on patterned surfaces; Flory-Huggins interaction parameter for polystyrene/poly-2-vinylpyridine (PS/P{sub 4}VP) blends; phase separation-induced patterns in dPS/PVME and dPEP/PEP blends; and high-resolution lateral imaging studies of phase separation and dewetting by scanning transmission X-ray microscopy (STXM) and photoemission electron microscopy (PEEM).
Date:
January 17, 2000
Creator:
Rafailovich, Miriam & Sokolov, Jonathan
Object Type:
Report
System:
The UNT Digital Library
Final state interaction in heavy hadron decay
I present a critical account of the final-state interaction (FSI) in two-body B decays from viewpoint of the hadron picture. I emphasize that the phase and the magnitude of decay amplitude are related to each other by a dispersion relation. In a model phase of FSI motivated by experiment, I illustrate how much the magnitude of amplitude can deviate from its factorization value by the FSI.
Date:
January 17, 2000
Creator:
Suzuki, Mahiko
Object Type:
Article
System:
The UNT Digital Library
In situ XAFS of the Li{sub x}Ni{sub 0.8}Co{sub 0.2} cathode for lithium-ion batteries
The layered LiNi{sub 0.8}Co{sub 0.2}O{sub 2} system is being considered as a new cathode material for the lithium-ion battery. Compared with LiCoO{sub 2}, the standard cathode formulation, it possesses improved electrochemical performance at a projected lower cost. In situ x-ray absorption fine-structure spectroscopy (XAFS) measurements were conducted on a cell cycled at a moderate rate and normal Li-ion operating voltages (3.0--4.1 V). The XAFS data collected at the Ni and Co edges approximately every 30 min. revealed details about the response of the cathode to Li insertion and extraction. These measurements on the Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2} cathode (0.29 < x < 0.78) demonstrated the excellent reversibility of the cathode's short-range structure. However, the Co and Ni atoms behaved differently in response to Li insertion. This study corroborates previous work that explains the XAFS of the Ni atoms in terms of a Ni{sup 3+} Jahn-Teller ion. An analysis of the metal-metal distances suggests, contrary to a qualitative analysis of the x-ray absorption near-edge structure (XANES), that the Co{sup 3+} is oxidized to the maximum extent possible (within the Li content range of this experiment) at x = 0.47 {+-} 0.04, and further oxidation occurs at the Ni site.
Date:
January 17, 2000
Creator:
Kropf, J. & Johnson, C. S.
Object Type:
Article
System:
The UNT Digital Library
THE INTERACTIONS OF HEAVY QUARKONIUM: SOME RECENT RESULTS
Some recent developments in the theory of heavy quarkonium interactions are presented. First, the authors consider quarkonium-quarkonium scattering at very low energies--an analog of the Van der Waals interaction. These long-range forces have very surprising properties in QCD--in particular, as a consequence of scale anomaly, the strength of the interaction at large distances appears independent of the coupling constant and is entirely determined by the non-perurbative vacuum energy density. Second, they argue that the scale anomaly can play a dominant role also in high-energy scattering, and discuss the possible origin of the soft Pomeron.
Date:
January 17, 2000
Creator:
Kharzeev, D.
Object Type:
Article
System:
The UNT Digital Library
Investigation of nonlinear dynamic soil property at the Savannah River Site
This document summarizes laboratory dynamic soil testing investigations conducted by the University of Texas at Austin (UTA) for the Savannah River Site (SRS) (Stokoe et al., 1995a, Stokoe et al., 1995b, Sponseller and Stokoe, 1995). The purpose of the investigation is to provide an evaluation of past testing results in the context of new test data and the development of consistent site wide models of material strain dependencies based upon geologic formation, depth, and relevant index properties.
Date:
January 17, 2000
Creator:
Lee, R.C.
Object Type:
Report
System:
The UNT Digital Library
Low temperature growth of ultrananocrystalline diamond on glass substrates for field emission applications.
Recent studies of field emission from diamond have focused on the feasibility of growing diamond films on glass substrates, which are the preferred choice for cost-effective, large area flat panel displays. However, diamond growth on glass requires temperatures {le} 500 C, which is much lower than the temperature needed for growing conventional microwave plasma chemical vapor deposition (CVD) diamond films. In addition, it is desirable to minimize the deposition time for cost-effective processing. The authors have grown ultrananocrystalline diamond (UNCD) films using a unique microwave plasma technique that involves CH{sub 4}-Ar gas mixtures, as opposed to the conventional CH{sub 4}-H{sub 2} plasma CVD method. The growth species in the CH{sub 4}-Ar CVD method are C{sub 2} dimers, resulting in lower activation energies and consequently the ability to grow diamond at lower temperatures than conventional CVD diamond processes. For the work discussed here, the UNCD films were grown with plasma-enhanced chemical vapor deposition (PECVD) at low temperatures on glass substrates coated with Ti thin films. The turn-on field was as low as 3 V/{mu}m for a film grown at 500 C with a gas chemistry of 1%CH{sub 4}/99%/Ar at 100 Torr, and 7 V/{mu}m for a film grown at 350 C. …
Date:
January 17, 2000
Creator:
Corrigan, T. D.; Krauss, A. R.; Gruen, D. M.; Auciello, O. & Chang, R. P. H.
Object Type:
Article
System:
The UNT Digital Library
Molecular modeling of the structure and dynamics of the interlayer and surface species of mixed-metal layered hydroxides: Chloride and water in hydrocalumite (Friedel's salt)
The dynamical behavior of Cl{sup {minus}} and H{sub 2}O molecules in the interlayer and on the (001) surface of the Ca-aluminate hydrate hydrocalumite (Friedel's salt) over a range of temperatures from {minus}100 to 300 C is studied using the technique of isothermal-isobaric molecular dynamics computer simulations. This phase is currently the best available model compound for other, typically more disordered, mixed-metal layered hydroxides. The computed crystallographic parameters and density are in good agreement with available X-ray diffraction data and the force field developed for these simulations preserves the structure and density to within less than 2% of their measured values. In contrast to the highly ordered arrangement of the interlayer water molecules interpreted from the X-ray data, the simulations reveal significant dynamic disorder in water orientations. At all simulated temperatures, the interlayer water molecules undergo rapid librations (hindered hopping rotations) around an axis essentially perpendicular to the layers. This results in breaking and reformation of hydrogen bonds with the neighboring Cl{sup {minus}} anions and in a time-averaged nearly uniaxial symmetry at Cl{sup {minus}}, in good agreement with recent {sup 35}Cl NMR measurements. Power spectra of translational, vibrational, and vibrational motions of interlayer and surface Cl{sup {minus}} and H{sub 2}O were …
Date:
January 17, 2000
Creator:
Kalinichev, Andrey G.; Kirkpatrick, R. James & Cygan, Randall T
Object Type:
Article
System:
The UNT Digital Library
RPP Environmental Permits and Related Documentation
This document contains the current list of environmental permits and related documentation for TWRS facilities and activities.
Date:
January 17, 2000
Creator:
Dexter, M. L.
Object Type:
Report
System:
The UNT Digital Library
Sources of Information on Wind Energy
A 2-color, 7.25-inch by 8.5-inch, one-fold pamphlet that lists the names and addresses of organizations that can be contacted for information on wind energy
Date:
January 17, 2000
Creator:
O'Dell, K.
Object Type:
Book
System:
The UNT Digital Library
Spectral Resolution for Five-Element, Filtered, X-Ray Detector (XRD) Arrays Using the Methods of Backus and Gilbert
The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining spectra from a 5-channel, filtered array of x-ray detectors (XRD's). This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({le}2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with the unfold method currently in use. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV black-body) and the unfold. This function may be used as an initial trial function for iterative methods or a regularization model.
Date:
January 17, 2000
Creator:
FEHL,DAVID LEE; BIGGS,F.; CHANDLER,GORDON A. & STYGAR,WILLIAM A.
Object Type:
Article
System:
The UNT Digital Library
Technical Basis for Radiological Workplace Air Monitoring and Sampling for the River Corridor Project 300 area
This report documents the technical basis by which the workplace air monitoring and sampling program is operated in the 324 and 327 Buildings.
Date:
January 17, 2000
Creator:
Mantooth, D. S.
Object Type:
Report
System:
The UNT Digital Library
Two- and three-dimensional ultrananocrystalline diamond (UNCD) structures for a high resolution diamond-based MEMS technology.
Silicon is currently the most commonly used material for the fabrication of microelectromechanical systems (MEMS). However, silicon-based MEMS will not be suitable for long-endurance devices involving components rotating at high speed, where friction and wear need to be minimized, components such as 2-D cantilevers that may be subjected to very large flexural displacements, where stiction is a problem, or components that will be exposed to corrosive environments. The mechanical, thermal, chemical, and tribological properties of diamond make it an ideal material for the fabrication of long-endurance MEMS components. Cost-effective fabrication of these components could in principle be achieved by coating Si with diamond films and using conventional lithographic patterning methods in conjunction with e. g. sacrificial Ti or SiO{sub 2} layers. However, diamond coatings grown by conventional chemical vapor deposition (CVD) methods exhibit a coarse-grained structure that prevents high-resolution patterning, or a fine-grained microstructure with a significant amount of intergranular non-diamond carbon. The authors demonstrate here the fabrication of 2-D and 3-D phase-pure ultrananocrystalline diamond (UNCD) MEMS components by coating Si with UNCD films, coupled with lithographic patterning methods involving sacrificial release layers. UNCD films are grown by microwave plasma CVD using C{sub 60}-Ar or CH{sub 4}-Ar gas mixtures, which …
Date:
January 17, 2000
Creator:
Auciello, O.; Krauss, A. R.; Gruen, D. M.; Busmann, H. G.; Meyer, E. M.; Tucek, J. et al.
Object Type:
Article
System:
The UNT Digital Library
3-D Numerical Modeling of a Complex Salt Structure
Reliably processing, imaging, and interpreting seismic data from areas with complicated structures, such as sub-salt, requires a thorough understanding of elastic as well as acoustic wave propagation. Elastic numerical modeling is an essential tool to develop that understanding. While 2-D elastic modeling is in common use, 3-D elastic modeling has been too computationally intensive to be used routinely. Recent advances in computing hardware, including commodity-based hardware, have substantially reduced computing costs. These advances are making 3-D elastic numerical modeling more feasible. A series of example 3-D elastic calculations were performed using a complicated structure, the SEG/EAGE salt structure. The synthetic traces show that the effects of shear wave propagation can be important for imaging and interpretation of images, and also for AVO and other applications that rely on trace amplitudes. Additional calculations are needed to better identify and understand the complex wave propagation effects produced in complicated structures, such as the SEG/EAGE salt structure.
Date:
February 17, 2000
Creator:
House, L.; Larsen, S. & Bednar, J. B.
Object Type:
Article
System:
The UNT Digital Library
Aequorin as a bioluminescent indicator for use in the determination of biomolecules in single cells. Final technical report
During this funding period, the laboratories of Drs. Anderson and Daunert have performed a considerable amount of work toward addressing the issues associated with small volume analysis necessary for single cell studies. In that respect, their research has been focused on (1) developing new assays that can be miniaturized and are suitable for small volume and single cell analysis; (2) fabricating pL-vials that simulate the volume of single cells and setting up instrumentation capable of low-volume detection; (3) developing reproducible and reliable microinjection techniques; (4) developing methods of analysis for biomolecules in the pL-vials and employing these assays in the detection of biomolecules in single cells. The accomplishments attained in all these areas are described below. A total of 24 publications and 35 presentations have resulted from this work.
Date:
February 17, 2000
Creator:
Daunert, Sylvia
Object Type:
Report
System:
The UNT Digital Library
Am/Cm Canister Temperature Evaluation in Cim5
To facilitate the evaluation of alternate canister designs, 2 canisters were outfitted with thermocouples at elevations of 1/2, 3 1/2, and 6 1/2 inches from the canister bottom. The canisters were fabricated from two inch diameter schedule 10 and two inch diameter schedule 40 stainless steel pipe. Each canister was filled with approximately 2 kilograms of 49 wt percent lanthanide (Ln) loaded 25SrABS glass during 5 inch Cylindrical Induction Melter (CIM5) runs for TTR Tasks 3.03 and 4.03. Melter temperature, total mass of glass poured, and the glass pour rates were almost identical in both runs. The schedule 40 canister has a slightly smaller ID compared to the schedule 10 canister and therefore filled to a level of 9.5 inches compared to 8.0 inches for the schedule 40 canister. The schedule 40 canister had an empty mass of 1906 grams compared to 919 grams for the schedule 10 canister. The schedule 10 canister was found to have a higher maximum surface temperature by about 50--100 C (depending on height) during the glass pour compared to the schedule 40 canister. The additional thermal mass of the schedule 40 canister accounts for this difference. Once filled with glass, each of the canisters …
Date:
February 17, 2000
Creator:
Baich, M. A.
Object Type:
Report
System:
The UNT Digital Library
Automatic scheme selection for toolkit hex meshing
Current hexahedral mesh generation techniques rely on a set of meshing tools, which when combined with geometry decomposition leads to an adequate mesh generation process. Of these tools, sweeping tends to be the workhorse algorithm, accounting for at least 50% of most meshing applications. Constraints which must be met for a volume to be sweepable are derived, and it is proven that these constraints are necessary but not sufficient conditions for sweepability. This paper also describes a new algorithm for detecting extruded or sweepable geometries. This algorithm, based on these constraints, uses topological and local geometric information, and is more robust than feature recognition-based algorithms. A method for computing sweep dependencies in volume assemblies is also given. The auto sweep detect and sweep grouping algorithms have been used to reduce interactive user time required to generate all-hexahedral meshes by filtering out non-sweepable volumes needing further decomposition and by allowing concurrent meshing of independent sweep groups. Parts of the auto sweep detect algorithm have also been used to identify independent sweep paths, for use in volume-based interval assignment.
Date:
February 17, 2000
Creator:
White, David R. & Tautges, Timothy J.
Object Type:
Article
System:
The UNT Digital Library
Beam Control for Ion Induction Accelerators
Coordinated bending and acceleration of an intense space-charge-dominated ion beam has been achieved for the first time. This required the development of a variable waveform, precision, bi-polar high voltage pulser and a precision, high repetition rate induction core modulator. Waveforms applied to the induction cores accelerate the beam as the bi-polar high voltage pulser delivers a voltage ramp to electrostatic dipoles which bend the beam through a 90 degree permanent magnet quadrupole lattice. Further work on emittance minimization is also reported.
Date:
February 17, 2000
Creator:
Sangster, T.C. & Ahle, L.
Object Type:
Report
System:
The UNT Digital Library
Cap plasticity models and compactive and dilatant pre-failure deformation
At low mean stresses, porous geomaterials fail by shear localization, and at higher mean stresses, they undergo strain-hardening behavior. Cap plasticity models attempt to model this behavior using a pressure-dependent shear yield and/or shear limit-state envelope with a hardening or hardening/softening elliptical end cap to define pore collapse. While these traditional models describe compactive yield and ultimate shear failure, difficulties arise when the behavior involves a transition from compactive to dilatant deformation that occurs before the shear failure or limit-state shear stress is reached. In this work, a continuous surface cap plasticity model is used to predict compactive and dilatant pre-failure deformation. During loading the stress point can pass freely through the critical state point separating compactive from dilatant deformation. The predicted volumetric strain goes from compactive to dilatant without the use of a non-associated flow rule. The new model is stable in that Drucker's stability postulates are satisfied. The study has applications to several geosystems of current engineering interest (oil and gas reservoirs, nuclear waste repositories, buried targets, and depleted reservoirs for possible use for subsurface sequestration of greenhouse gases).
Date:
February 17, 2000
Creator:
FOSSUM,ARLO F. & FREDRICH,JOANNE T.
Object Type:
Article
System:
The UNT Digital Library
Characteristics of GaAsSb single quantum well lasers emitting near 1.3 {micro}m
The authors report data on GaAsSb single quantum well lasers grown on GaAs substrates. Room temperature pulsed emission at 1.275 {micro}m in a 1,250 {micro}m-long device has been observed. Minimum threshold current densities of 535 A/cm{sup 2} were measured in 2000 {micro}m long lasers. The authors also measured internal losses of 2--5 cm{sup {minus}1}, internal quantum efficiencies of 30-38% and characteristic temperature T{sub 0} of 67--77 C. From these parameters a gain constant G{sub 0} of 1,660 cm{sup {minus}1} and a transparency current density J{sub tr} of 134 A/cm{sup 2} were calculated. The results indicate the potential for fabricating 1.3 {micro}m VCSELs from these materials.
Date:
February 17, 2000
Creator:
SPAHN,OLGA B. & KLEM,JOHN F.
Object Type:
Article
System:
The UNT Digital Library
Civil Rights Division: Policies and Procedures for Establishing Litigation Priorities, Tracking and Managing Casework, and Disseminating Litigation Results
Correspondence issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed the Department of Justice's Civil Rights Division's, which uses the abbreviation CRT, management of its responsibilities, focusing on: (1) CRT's role in establishing and coordinating governmentwide civil rights policies and litigation priorities; (2) the division's guidelines, policies, and procedures for tracking and managing its caseload; and (3) the division's guidelines, policies, and procedures for disseminating the results of litigation."
Date:
February 17, 2000
Creator:
United States. General Accounting Office.
Object Type:
Text
System:
The UNT Digital Library