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449
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203
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112
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106
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67
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64
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15,313 Matching Results
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An archaeological reconnaissance of a 14 mile section of the East Fork Poplar Creek for the Environmental Restoration Project, Anderson and Roane Counties, Tennessee
At the request of the US Army Corps of Engineers, Nashville District, Nashville, Tennessee, an archaeological reconnaissance of the potential impact areas of the Environmental Restoration Project (ERP) along the East Fork Poplar Creek was conducted during the period December 16, 1991, and March 3, 1992. The reconnaissance was conducted in response to environmental evaluations as a result of the accidental spillage of approximately 293,000 pounds of mercury, radionuclides, heavy metals and other compounds. The reconnaissance to assess adverse impacts to cultural resources located within the boundaries of Federally-licensed, permitted, funded or assisted projects was conducted in compliance with the National Historic Preservation Act of 1966, National Environmental Policy Act of 1969 and Executive Order 11593.
Date:
January 1, 1993
Creator:
DuVall, G. D.
Object Type:
Report
System:
The UNT Digital Library
Are Bilinear Quadrilaterals Better Than Linear Triangles?
This paper compares the theoretical effectiveness of bilinear approximation over quadrilaterals with linear approximation over triangles. Anisotropic mesh transformation is used to generate asymptotically optimally efficient meshes for piecewise linear interpolation over triangles and bilinear interpolation over quadrilaterals. For approximating a convex function, although bilinear quadrilaterals are more efficient, linear triangles are more accurate and may be preferred in finite element computations; whereas for saddle-shaped functions, quadrilaterals may offer a higher order approximation on a well-designed mesh. A surprising finding is different grid orientations may yield an order of magnitude improvement in approximation accuracy.
Date:
January 1, 1993
Creator:
D'Azevedo, E.F.
Object Type:
Report
System:
The UNT Digital Library
Are there atmospheric neutrino oscillations
The neutrino oscillation explanation ([nu][sub [mu]] [yields] [nu][sub [tau]]) of the atmospheric neutrino deficit is often discussed but is far from widely accepted. This paper discusses several experimental observations, and how a consistent picture pointing towards neutrino oscillations might develop.
Date:
January 1, 1993
Creator:
Goodman, M.C.
Object Type:
Article
System:
The UNT Digital Library
Aromatic-radical oxidation chemistry
There are anomalously high CO[sub 2] concentrations early in the reaction sequence in the oxidation of cyclopentadiene. A number of plausible mechanisms have been developed. NO[sub 2] and CO have been added to the reacting mixture, to assist in selecting the best mechanism. Effects of these chemical perturbations were studied.
Date:
January 1, 1993
Creator:
Glassman, I. & Brezinsky, K.
Object Type:
Report
System:
The UNT Digital Library
Asphaltene reaction via supercritical fluid extraction
Supercritical fluid extraction (SFE) of bitumen was carried out in a continuous extractor using propane as the solvent at several temperatures and pressures. The asphaltene contents of the residual fractions in the extractor were compared to the asphaltene content of the original bitumen. Asphaltenes were defined as pentane insolubles in this study. It was found that the absolute asphaltene content of the residual fractions exceeded the asphaltene content of the original bitumen. Even when the asphaltene content was prorated by the weight percent of the residual material, it was found to be higher than the original asphaltene content. The data established that the types of compounds separating as asphaltenes changed as the nature of the mixture was altered by SFE. The data also indicated that it may be inappropriate to perform asphaltene material balances to assess the amount of precipitate. The original asphaltene content of a bitumen that is undergoing compositional changes in a sequence of operations may not be an accurate measure of the precipitating tendency of the bitumen in production and processing operations. The asphaltene content of the residual material varied depending on the extraction conditions and was as much as 3--5 times the original asphaltene content. The …
Date:
January 1, 1993
Creator:
Deo, M. D. & Hanson, F. V.
Object Type:
Article
System:
The UNT Digital Library
Assessment of dose during an SGTR
The Nuclear Regulatory Commission requires utilities to determine the response of a pressurized water reactor to a steam generator tube rupture (SGTR) as part of the safety analysis for the plant. The SGTR analysis includes assumptions regarding the iodine concentration in the reactor coolant system (RCS) due to iodine spikes, primary flashing and bypass fractions, and iodine partitioning in the secondary coolant system (SCS). Experimental and analytical investigations have recently been completed wherein these assumptions were tested to determine whether and to what degree they were conservative (that is, whether they result in a calculated iodine source term/dose that is at least as large or larger than that expected during an actual event). The current study has the objective to assess the overall effects of the results of these investigations on the calculated iodine dose to the environment during an SGTR. To assist in this study, a computer program, DOSE, was written. This program uses a simple, non-mechanistic model to calculate the iodine source term to the environment during an SGTR as a function of water mass inventories and flow rates and iodine concentrations in the RCS and SCS. The principal conclusion of this study is that the iodine concentration …
Date:
January 1, 1993
Creator:
Adams, J. P.
Object Type:
Report
System:
The UNT Digital Library
Assessment of dose during an SGTR. [Steam Generator Tube Rupture (SGTR)]
The Nuclear Regulatory Commission requires utilities to determine the response of a pressurized water reactor to a steam generator tube rupture (SGTR) as part of the safety analysis for the plant. The SGTR analysis includes assumptions regarding the iodine concentration in the reactor coolant system (RCS) due to iodine spikes, primary flashing and bypass fractions, and iodine partitioning in the secondary coolant system (SCS). Experimental and analytical investigations have recently been completed wherein these assumptions were tested to determine whether and to what degree they were conservative (that is, whether they result in a calculated iodine source term/dose that is at least as large or larger than that expected during an actual event). The current study has the objective to assess the overall effects of the results of these investigations on the calculated iodine dose to the environment during an SGTR. To assist in this study, a computer program, DOSE, was written. This program uses a simple, non-mechanistic model to calculate the iodine source term to the environment during an SGTR as a function of water mass inventories and flow rates and iodine concentrations in the RCS and SCS. The principal conclusion of this study is that the iodine concentration …
Date:
January 1, 1993
Creator:
Adams, J. P.
Object Type:
Report
System:
The UNT Digital Library
Assessment of the Available (Sup 233)U Cross Sections Evaluations in the Calculation of Critical Benchmark Experiments
In this report we investigate the adequacy of the available {sup 233}U cross-section data for calculation of experimental critical systems. The {sup 233}U evaluations provided in two evaluated nuclear data libraries, the U. S. Data Bank [ENDF/B (Evaluated Nuclear Data Files)] and the Japanese Data Bank [JENDL (Japanese Evaluated Nuclear Data Library)] are examined. Calculations were performed for six thermal and ten fast experimental critical systems using the Sn transport XSDRNPM code. To verify the performance of the {sup 233}U cross-section data for nuclear criticality safety application in which the neutron energy spectrum is predominantly in the epithermal energy range, calculations of four numerical benchmark systems with energy spectra in the intermediate energy range were done. These calculations serve only as an indication of the difference in calculated results that may be expected when the two {sup 233}U cross-section evaluations are used for problems with neutron spectra in the intermediate energy range. Additionally, comparisons of experimental and calculated central fission rate ratios were also made. The study has suggested that an ad hoc {sup 233}U evaluation based on the JENDL library provides better overall results for both fast and thermal experimental critical systems.
Date:
January 1, 1993
Creator:
Leal, L.C.
Object Type:
Report
System:
The UNT Digital Library
Assessment of the impact of HTSCs on superconducting fault-current limiters. [High Temperature SuperConductors (HTSCs)]
The possible impact of nitrogen-cooled superconductors on the desip and cost of superconducting fault-current limiters is assessed by considering the technical specifications such devices must meet and by comparing material properties of 77-K and 4-K superconductors. The main advantages of operating superconductors at 77 K are that the refrigeration operating cost is reduced by a factor of up to 25 and the refrigeration capital cost is reduced by a factor of up to 10. The heat capacity is several orders of magnitude Larger at 77 K and at 4 K. This phenomenon increases conductor stability against flux jumps but makes switching from the superconducting to the normal state slow and difficult. Therefore, a high critical current density, probably at least 10[sup 5] A/cm[sup 2], is required.
Date:
January 1, 1993
Creator:
Giese, R.F. (Argonne National Lab., IL (United States)) & Runde, M. (Energiforsyningens Forskningsinstitutt A/S, Trondheim (Norway))
Object Type:
Article
System:
The UNT Digital Library
Astrophysics with MILAGRO
This paper describes how data from a new type of air shower detector, MILAGRO can shed light on a variety of interesting problems in astrophysics. MILAGRO has the capability to make observations of VHE/UHE emission from the recently discovered TeV gamma-ray source Markarian 421, an Active Galactic Nucleus (AGN). An observation of the attenuation of this signal in the range of 1--20 TeV can be used to make the first measurement of the intergalactic infrared radiation. We will also describe how MILAGRO can improve the existing limits on the density of Primordial Black Holes (PBH) by three orders of magnitude. Finally, we will discuss how this instrument can be used to measure the diffuse galactic emission of gamma-rays which must come from the disk.
Date:
January 1, 1993
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Asymmetric-cut monochromator with adjustable asymmetry
A variable incident angle, asymmetric cut, double crystal monochromator was tested for use on beamlines at the Advanced Photon Source (APS). For both undulator and wiggler beams the monochromator can expand area of footprint of beam on surface of the crystals to 50 times the area of incident beam; this will reduce the slope errors by a factor of 2500. The asymmetric cut allows one to increase the acceptance angle for incident radiation and obtain a better match to the opening angle of the incident beam. This can increase intensity of the diffracted beam by a factor of 2 to 5 and can make the beam more monochromatic, as well. The monochromator consists of two matched, asymmetric cut (18 degrees), silicon crystals mounted so that they can be rotated about three independent axes. Rotation around the first axis controls the Bragg angle. The second rotation axis is perpendicular to the diffraction planes and controls the increase of the area of the footprint of the beam on the crystal surface. Rotation around the third axis controls the angle between the surface of the crystal and the wider, horizontal axis for the beam and can make the footprint a rectangle with a …
Date:
January 1, 1993
Creator:
Smither, R.K. & Fernandez, P.B.
Object Type:
Article
System:
The UNT Digital Library
Asymptotic derivation of the simplified P[sub n] equations
The diffusion and simplified P[sub N] equations are derived from the transport equation by means of an asymptotic expansion in which the diffusion equation is the leading order approximation and the simplified P[sub N] equations are higher-order approximations. In addition, the simplified P[sub N] equations are reformulated in a canonical'' form that greatly facilitates the formulation of boundary conditions and the implementation of the resulting problem in a conventional multigroup diffusion code. Numerical comparisons of S[sub N], diffusion, and simplified P[sub N] solutions show that the simplified P[sub N] solutions often contain most of the transport corrections for the diffusion approximation.
Date:
January 1, 1993
Creator:
Larsen, Edward W.; Morel, Jim E. & McGhee, John M.
Object Type:
Article
System:
The UNT Digital Library
ATF beamline 1 analysis spectrometer
We describe the design parameters and expected performance of the analysis spectrometer for beamline 1 at the BNL Accelerator Test Facility. The spectrometer should be well suited for measuring the change in energy caused by the first generation laser acceleration experiments.
Date:
January 1, 1993
Creator:
Fernow, R.C.; Kirk, H.G. & Ulc, S.
Object Type:
Report
System:
The UNT Digital Library
ATF beamline 1 analysis spectrometer
We describe the design parameters and expected performance of the analysis spectrometer for beamline 1 at the BNL Accelerator Test Facility. The spectrometer should be well suited for measuring the change in energy caused by the first generation laser acceleration experiments.
Date:
January 1, 1993
Creator:
Fernow, R. C.; Kirk, H. G. & Ulc, S.
Object Type:
Report
System:
The UNT Digital Library
The Atlas of Major Appalachian Basin Gas Plays: Data collection and compilation
Task 2 of the ``Atlas of Major Appalachian Basin Gas Plays`` a is the data collection and compilation phase of the project. The prime objective is to collect information by pool, i.e., producing reservoir within a field, that will provide (1) basic reservoir data, (2) reservoir parameters, (3) fluid and gas properties, and (4) volumetric data. It is imperative that all data elements be well understood by all participants to facilitate this process. This report presents an overview of data collection topics. Three families of data that be part of this project: (1) the data base of pool information, (2) drawings, charts, and maps, and (3) text data, including bibliographic information. An initial data definition will be presented with an emphasis on the data base of basic information by pool. Because of the direct bearing on Task 2 of the project and the development of a data base as a deliverable product, this report will concentrate mainly on data definition and collection. A basic data collection strategy is included.
Date:
January 1, 1993
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Atom probe field ion microscopy and related topics: A bibliography 1991
This report contains a bibliography for 1991 on the following topics: Atom probe field ion microscopy; field desorption mass spectrometry; field emission; field ion microscopy; and field emission theory.
Date:
January 1, 1993
Creator:
Russell, K. F. & Miller, M. K.
Object Type:
Report
System:
The UNT Digital Library
[Atomic and electronic structure of metals and alloys: Clean surfaces and chemisorbed molecules]
Ultrapure Tb was further purified and surface cleaning procedures developed for basal plane and (11[bar 2]0) surface of Tb. Structure of both surfaces was found to be relaxed: (0001) is contracted by 3.9% in the first and expanded by 1.4% in second interlayer spacing; (11[bar 2]0) is contracted by 3.3% in first layer and shows a change in registry. Thin films of Gd, Tb, Dy, Ho, and Er were grown on W[l brace]110[r brace] substrate in ultrahigh vacuum. Studies have been carried out on epitaxial systems involving Cu, Fe and Mn on Fe and Pt, Cu, and Pd substrates, respectively; new metastable crystalline phases have been found. Studies of possible ferromagnetism in 4d elements (Rh, Ru) and relativistic effects in electron band structure of Cu[l brace]111[r brace] have been completed and published. Plans for the following year are given.
Date:
January 1, 1993
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Attachment 4, RLCA calculation No. P191-1/7, Review of 105K reactor tank lower supports
Confirmatory analyses were performed to examine the adequacy of the 105-K Reactor Tank Bottom Supports. The supports were reviewed for updated loads from a separate confirmatory calculation for the reactor tank and bottom tubesheet. The lower supports were found to be adequate for the current loading even with conservatisms applied to allow for analysis of the nonlinear friction/gapped support design.
Date:
January 1, 1993
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Attack to Cut the Peninsula 19-XXI
Map illustrating the attack to cut the peninsula.
Date:
1993~
Creator:
Lambach R.
Object Type:
Map
System:
The UNT Digital Library
Automated analysis for microcalcifications in high resolution digital mammograms
Digital mammography offers the promise of significant advances in early detection of breast cancer. Our overall goal is to design a digital system which improves upon every aspect of current mammography technology: the x-ray source, detector, visual presentation of the mammogram and computer-aided diagnosis capabilities. This paper will discuss one part of our whole-system approach -- the development of a computer algorithm using gray-scale morphology to automatically analyze and flag microcalcifications in digital mammograms in hopes of reducing the current percentage of false-negative diagnoses, which is estimated at 20%. The mammograms used for developing this ``mammographers assistant`` are film mammograms which we have digitized at either 70 {mu}m or 35 {mu}m per pixel resolution with 4096 (12 bits) of gray level per pixel. For each potential microcalcification detected in these images, we compute a number of features in order to distinguish between the different kinds of objects detected.
Date:
January 1, 1993
Creator:
Mascio, Laura N.; Hernandez, Jose M. & Logan, Clinton M.
Object Type:
Article
System:
The UNT Digital Library
Automated Fuel Element Closure Welding System
The Automated Fuel Element Closure Welding System is a robotic device that will load and weld top end plugs onto nuclear fuel elements in a highly radioactive and inert gas environment. The system was developed at Argonne National Laboratory-West as part of the Fuel Cycle Demonstration. The welding system performs four main functions, it (1) injects a small amount of a xenon/krypton gas mixture into specific fuel elements, and (2) loads tiny end plugs into the tops of fuel element jackets, and (3) welds the end plugs to the element jackets, and (4) performs a dimensional inspection of the pre- and post-welded fuel elements. The system components are modular to facilitate remote replacement of failed parts. The entire system can be operated remotely in manual, semi-automatic, or fully automatic modes using a computer control system. The welding system is currently undergoing software testing and functional checkout.
Date:
January 1, 1993
Creator:
Wahlquist, D. R.
Object Type:
Article
System:
The UNT Digital Library
Backpropagation architecture optimization and an application in nuclear power plant diagnostics
This paper presents a Dynamic Node Architecture (DNA) scheme to optimize the architecture of backpropagation Artificial Neural Networks (ANNs). This network scheme is used to develop an ANN based diagnostic adviser capable of identifying the operating status of a nuclear power plant. Specifically, a root'' network is trained to diagnose if the plant is in a normal operating condition or not. In the event of an abnormal condition, and other classifier'' network is trained to recognize the particular transient taking place. these networks are trained using plant instrumentation data gathered during simulations of the various transients and normal operating conditions at the Iowa Electric Light and Power Company's Duane Arnold Energy Center (DAEC) operator training simulator.
Date:
January 1, 1993
Creator:
Basu, A. & Bartlett, E.B.
Object Type:
Article
System:
The UNT Digital Library
Bacliff Quadrangle
Topographic map of a portion of Texas from the United States Geological Survey (USGS) project. The map includes towns, historic or notable sites, bodies of water, and other geologic features. Scale 1:24000
Date:
1993
Creator:
Geological Survey (U.S.)
Object Type:
Map
System:
The Portal to Texas History
[Band electronic structures and crystal packing forces]
We investigated the electronic and structural properties of low-dimensional materials and explored the structure-property correlations governing their physical properties. Progress was made on how to interpret the scanning tunneling microscopy and atomic force microscopy images of layered materials and on how to account for charge density wave instabilities in 2-D metals. Materials studied included transition metal chalcogenides, transition metal halides, organic conducting salts, Mo bronzes, A[sub 2]PdH[sub 2], fullerenes, squarate tetrahydrate polymers Fe, Cu(C[sub 4]O[sub 4])4[center dot]H[sub 2]O, BEDT salts, etc.
Date:
January 1, 1993
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library