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14,163
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459
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203
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112
USGS Topographic Map Collection
106
Congressional Research Service Reports
67
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64
Office of Technology Assessment
63
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27
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42
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34
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15,321 Matching Results
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Analysis of transposon-insertion mutants of Clostridium acetobutylicum ATCC 824
None
Date:
December 31, 1993
Creator:
Mattsson, D. M. & Rogers, P.
Object Type:
Article
System:
The UNT Digital Library
Analysis, scientific computing and fundamental studies in fluid mechanics. Summary report number 16, April 1, 1992--March 31, 1993
Summaries are given of the progress on each of the following research projects: (1) vortex dynamics, vortical states and turbulence; (2) vortical states for plane Couette flow; (3) homotopy methods for nonsymmetrical eigenproblems; (4) the Recursive Projection Method (RPM); (5) axisymmetric flow with swirl; and (6) pattern selection in solidifying systems.
Date:
December 31, 1993
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Analytical electron microscopy examination of solid reaction products in long-term test of SRL 200 waste glasses
Alteration phases, found on the leached surfaces and present as colloids in the leachates of 200-based frit (fully active and simulated) nuclear waste glass, reacted under static test conditions, at a surface area to leachate volume ratio of 20,000 m{sup {minus}1} for 15 days to 728 days, have been examined by analytical electron microscopy. The compositions of the secondary phases were determined using x-ray energy dispersive spectroscopy and electron energy loss spectroscopy, and structural analysis was accomplished by electron diffraction. Long-term samples of simulated glass, which had undergone an acceleration of reaction after 182 days, possessed a number of silicate secondary phases, including; smectite (iron silicate and potassium iron alumina-silicate, weeksite (uranium silicate), zeolite (calcium potassium alumino-silicate), tobermorite (calcium silicate), and a pure silica phase. However, uranium silicates and smectite have also been observed in tests, which have not undergone the acceleration of reaction, in both the leachate and leached layer, suggesting that these phases are not responsible for the acceleration of reaction.
Date:
December 31, 1993
Creator:
Buck, E. C.; Fortner, J. A.; Bates, J. K.; Feng, X.; Dietz, N. L.; Bradley, C. R. et al.
Object Type:
Article
System:
The UNT Digital Library
Analytical laboratory and mobile sampling platform. Progress report, October 1, 1993--December 31, 1993
Three compounds, trifluoromethane (CHF{sub 3}), 1,1,1,2- tetrafluoroethane (TFA), and octafluoropropane (C{sub 3}H{sub 8}), were compared to SF{sub 6} for use as vapor phase tracers. Dichlorodifluoromethane was also used once for comparison. Experiments were done to test sorption/degradation in a medium colored tuff with (saturated) and without water. A gas chromatograph with an electron capture detector was used. Detection limits were determined.
Date:
December 31, 1993
Creator:
Stetzenbach, K.
Object Type:
Report
System:
The UNT Digital Library
Analyzing organic sulfur in coal/char: Integrated mild degradation/XANES methods. [Quarterly] technical report, September 1--November 30, 1993
To address the acid rain problem effort has been expended on finding methods for the removal of sulfur from coal. Despite these efforts organic sulfur has proven very difficult to remove. Perhaps the single most important reason for this is the fact that the organic sulfur in coal remains very poorly characterized. Thus, objective of this study is to combine advanced nondestructive and advanced destructive methods of sulfur analysis for characterization of the organic sulfur in Illinois Basin coals and mild gasification chars derived from them. Thus, the study combines selective oxidation strategies, analytical pyrolysis, and sulfur X-ray Absorption Near Edge Structure Spectroscopy (XANES) analysis. In, addition identical samples are to be provided for W-Band EPR spectroscopy. During the previous quarter ten coal derived samples have been prepared with the sulfur content varing from 0.77 to 4.4%. Each sample has been submitted for XANES analysis, W-Band EPR analysis, and analytical pyrolysis. A mild gasification reactor has been designed and is undergoing final assembly.
Date:
December 31, 1993
Creator:
Palmer, S. R. & Huffman, G. P.
Object Type:
Report
System:
The UNT Digital Library
Aniline hydrogenolysis on the Pt(111) single crystal surface: Mechanisms for C-N bond activation
Hydrogenolysis of C-N bond on transition metals is a crucial step in hydrodenitrogenation (HDN) reactions. Despite the overall complexity of HDN processes, the details of important surface reactions can be characterized using model reactions of organonitrogen compounds on single crystal model catalysts. The structure and reactivity of well characterized aniline monolayers on the Pt(111) surface both in vacuum and in the presence of hydrogen is discussed here. Adsorption and reactions of aniline were studied by Gland and Somorjai on the Pt(111) and Pt(100) surfaces, and more recently by Benziger`s group on the Ni(111) and Ni(100) surfaces. On both Pt and Ni surfaces, aniline {pi} bonds through the aromatic ring with its ring parallel to the substrate surface.
Date:
December 31, 1993
Creator:
Huang, S. X.; Gland, J. L. & Fischer, D. A.
Object Type:
Report
System:
The UNT Digital Library
ANL/WSU radiation damage studies
We report preliminary results for the radiation hardness of (polystryrene) plastic scintillator stacks using a spectrum of energy hardened neutrons from a MARK-III TRIGA reactor. The total dose ranged from 100 KRad to 3MRad. The corresponding fluence was 3.8 {times} 10{sup 13} to 3.8 {times} 10{sup 14} (n/cm/cm) with the gamma contribution on the order 2--3% (of fluence). The measurements used Li-6, Li-7 Thermo-luminescence dosimeters. Radiochromic/GaF- Chromic film, and activated foils simultaneously allowing an inter-comparison of these various methods of dosimetry.
Date:
December 31, 1993
Creator:
Jankowski, D. J.; Lopiano, D.; Proudfoot, J.; Underwood, D.; Miles, L.; Neidiger, J. et al.
Object Type:
Article
System:
The UNT Digital Library
Annual site environmental report for calendar year 1993
The Western Area Power Administration (Western) has established a formal environmental protection, auditing, monitoring, and planning program that has been in effect since 1978. The significant environmental projects and issues Western was involved with in 1993 are discussed in this annual site environmental report. It is written to show the nature and effectiveness of the environmental protection program. The Department of Energy Order 5400.1, Chapter 2.4, requires the preparation of an annual site environmental report. Because Western has facilities located in 15 States, this report addresses the environmental activities in all the facilities as one ``site``. In 1993, Western provided power to more than 600 wholesale power customers consisting of cooperatives, municipalities, public utility districts, investor-owned utilities, federal and state agencies, irrigation districts, and project use customers. The wholesale power customers, in turn, provide service to millions of retail consumers in the States of California, Nevada, Montana, Arizona, Utah, New Mexico, Texas, North Dakota, South Dakota, Iowa, Colorado, Wyoming, Minnesota, Nebraska, and Kansas.
Date:
December 31, 1993
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
An anodic dissolution-based mechanism for the rapid cracking, ``pre-exposure`` phenomenon demonstrated by Al-Li-Cu alloys
Al-Li-Cu alloys have been observed to fail in less than 24 hours after removal from a one week immersion in aerated 3.5 w/o NaCl solution. Anodic dissolution-based mechanisms proposed previously for this phenomenon have been amended based on further experiment and characterization of the rapid cracking process. Amendments are based on studies of the relative electrochemical behavior of the microstructural elements in the subgrain boundary region, time to failure SCC testing in a simulated crack solution, evolution of crack potential and pH with time, fractographic examination of failed samples, and X-ray diffraction of films passivating crack walls. Results suggest that an active path exists along subgrain boundaries that is comprised of the highly reactive T{sub 1} (Al{sub 2}CuLi) precipitate phase and a solute depleted zone that does not readily passivate when exposed to the crack environment. The matrix phase does appear to passivate in the crack environment thereby confining the crack to the subgrain boundary region. This active path is enabled when cracks are isolated from a bulk environment, but is disabled otherwise. Potential and pH conditions required for cracking are discussed as is the formation of a hydrotalcite Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O film that appears to …
Date:
December 31, 1993
Creator:
Buchheit, R. G.; Wall, F. D.; Stoner, G. E. & Moran, J. P.
Object Type:
Article
System:
The UNT Digital Library
Antiproton production in heavy ion collisions
In high energy p-p and {alpha} {minus} {alpha} collisions, baryons are observed predominantly at rapidities near those of target and projectile; the mean rapidity shift of projectile and target nucleons is approximately one unit. In the central rapidity region, the number of baryons is quite small. In fact, the number of baryons and antibaryons is rather similar, indicating that most of these baryons are CREATED particles rather than projectile and target fragments. Antibaryon production is of interest in heavy ion collisions as enhanced antiquark production has been predicted as a potential signature of quark-gluon plasma formation. Antibaryons also provide a sensitive probe of the hadronic environment, via annihilation and/or mean field effects upon their final distributions. However, the collision dynamics also affect the baryon and antibaryon distributions. Baryons are more shifted toward midrapidity in nucleus-nucleus and p-p nucleus collisions than in p-p collisions, increasing the probability of annihilating the antibaryons. The interpretation of antibaryon yields is further complicated by collective processes which may take place in the dense hadronic medium formed in nucleus-nucleus collisions. Jahns and coworkers have shown that multistep processes can increase antibaryon production near threshold. Antiproton production is clearly very interesting, but is sensitive to a combination …
Date:
December 31, 1993
Creator:
Jacak, B. V. & Collaboration, NA44
Object Type:
Article
System:
The UNT Digital Library
Apparatus and method for extracting power from energetic ions produced in nuclear fusion
This invention is comprised of an apparatus and method of extracting power from energetic ions produced by nuclear fusion in a toroidal plasma to enhance respectively the toroidal plasma current and fusion reactivity. By injecting waves of predetermined frequency and phase traveling substantially in a selected poloidal direction within the plasma, the energetic ions become diffused in energy and space such that the energetic ions lose energy and amplify the waves. The amplified waves are further adapted to travel substantially in a selected toroidal direction to increase preferentially the energy of electrons traveling in one toroidal direction which, in turn, enhances or generates a toroidal plasma current. In an further adaptation, the amplified waves can be made to preferentially increase the energy of fuel ions within the plasma to enhance the fusion reactivity of the fuel ions. The described direct, or in situ, conversion of the energetic ion energy provides an efficient and economical means of delivering power to a fusion reactor.
Date:
December 31, 1993
Creator:
Fisch, N. J. & Rax, J. M.
Object Type:
Patent
System:
The UNT Digital Library
Apparatus and method for laser deposition of durable coatings
Disclosed are method and apparatus for depositing durable coatings onto the surface of a substrate without heating the entire substrate to high temperatures by using lasers to heat the substrate and dissociate a deposition gas. The apparatus comprises a deposition chamber for enclosing the substrate upon which a coating is to be deposited, gas delivery means for directing a flow of deposition gas on the substrate, a first laser for heating the substrate, and a second laser for irradiating the deposition gas to dissociate the gas. The method includes placing a substrate within a vacuum deposition chamber and directing a flow of deposition gas on the substrate. Then the substrate is heated with a first laser while the deposition gas is irradiated with a second laser to dissociate the deposition gas.
Date:
December 31, 1993
Creator:
Veligdan, J.T.; Vanier, P. & Barletta, R.E.
Object Type:
Patent
System:
The UNT Digital Library
Apparent temperature versus true temperature of silicon crystals as a function of their thickness using infrared measurements
The very high intensity x-ray beams that will be present at the Advanced Photon Source and other third generation synchrotron sources will require that the first optical element in the beamline and, possibly, the second optical element as well, be cooled to remove the heat deposited by the x-ray beam. In many of the beamlines this heat will be in the 1 to 5 kW range, and any failure of the cooling system will require a quick response from safety control circuits to shut off the beam before damage is done to the optical element. In many cases, this first optical element will be a silicon diffraction crystal. Viewing the surface of objects subjected to high heat fluxes with an infrared camera or infrared sensor has proved to be a very effective method for monitoring the magnitude and distribution of surface temperatures on the object. This approach has been quite useful in studies of cooling silicon crystals in monochromators subject to high heat loads. The main drawback to this method is that single crystals of silicon are partially transparent to the infrared radiation monitored in most infrared cameras. This means that the infrared radiation emitted from the surface contains a …
Date:
December 31, 1993
Creator:
Smither, R. K. & Fernandez, P. B.
Object Type:
Report
System:
The UNT Digital Library
Application of accident progression event tree technology to the Savannah River Site Defense Waste Processing Facility SAR analysis
The Accident Analysis in the Safety Analysis Report (SAR) for the Savannah River Site (SRS) Defense Waste Processing Facility (DWPF) has recently undergone an upgrade. Non-reactor SARs at SRS (and other Department of Energy (DOE) sites) use probabilistic techniques to assess the frequency of accidents at their facilities. This paper describes the application of an extension of the Accident Progression Event Tree (APET) approach to accidents at the SRS DWPF. The APET technique allows an integrated model of the facility risk to be developed, where previous probabilistic accident analyses have been limited to the quantification of the frequency and consequences of individual accident scenarios treated independently. Use of an APET allows a more structured approach, incorporating both the treatment of initiators that are common to more than one accident, and of accident progression at the facility.
Date:
December 31, 1993
Creator:
Brandyberry, M. D.; Baker, W. H.; Wittman, R. S. & Amos, C. N.
Object Type:
Article
System:
The UNT Digital Library
Application of artificial intelligence to reservoir characterization: An interdisciplinary approach. [Quarterly progress report], October 1--December 30, 1993
This basis of this research is to apply novel techniques from Artificial Intelligence and Expert Systems in capturing, integrating and articulating key knowledge from geology, geostatistics, and petroleum engineering to develop accurate descriptions of petroleum reservoirs. The ultimate goal is to design and implement a single powerful expert system for use by small producers and independents to efficiently exploit reservoirs. The first task under each of the concurrent phases of developing large-scale and small-scale reservoir descriptions is to identify the main knowledge sources. This task involves the identification of the critical variables that have an impact on large-scale heterogeneities. Because of the interdisciplinary nature of the project, we have had to develop a common vocabulary among the researchers to accomplish this identification task of Phases I and II. It was necessary for the computer science faculty and students to familiarize themselves with the information processed in geology geostatistics, and petroleum engineering. In addition, the geology and petroleum engineering researchers required instruction in the process of building expert systems. As part of the simulation task of Phase I and II, we have decomposed the design of the expert system into smaller component parts to get a clearer picture of what expert …
Date:
December 31, 1993
Creator:
Gamble, R. F.; Kerr, D. R.; Thompson, L. G. & Shenoi, S.
Object Type:
Report
System:
The UNT Digital Library
The application of electrodialysis to extend the lifetime of commercial electroplating baths
Electrodialysis has been investigated as a method to extend the lifetime of industrial electroplating solutions via the selective removal of inert electrolyte salts that build up during electroplating operations. The electrodialysis measurements were made using a commercially available plate-and frame-type cell and various combinations of Nafion cation ``change and either Tosflex or Neosepta anion exchange membranes. Two commercial plating solutions were studied: a zinc-tin bath in which there is a buildup of excess potassium hydroxide and a nickel-tungsten bath characterized by a buildup of excess sodium sulfate. Potassium hydroxide was effectively removed from the zinc-tin bath with very little loss of the heavy metals. Two configurations were investigated: a three compartment configuration with potassium hydroxide in the anolyte strip and sulfuric acid in the catholyte strip, and a two compartment configuration with sulfuric acid in the catholyte strip and the anode placed directly in the plating solution. In both cases potassium hydroxide was stripped from the plating solution at greater than 94% current efficiency, but at a slightly greater voltage in the three compartment cell due to increased resistance caused by the extra membrane. A three compartment configuration was used to remove sodium sulfate from the nickel-tungsten bath, with acid …
Date:
December 31, 1993
Creator:
Purdy, G.; Zawodzinski, C.; Smith, B. & Smith, W. H.
Object Type:
Article
System:
The UNT Digital Library
Application of hysteresis modeling to magnetic techniques for monitoring biaxial stress
A probe, consisting of two excitation coils and a detection coil wrapped around a core with a Hall probe between the pole pieces, has been used to measure indirectly the influence of biaxial stress on the magnetic properties of a ferromagnetic specimen, in this case annealed SAE-4130 steel. Properties measured indirectly included remanence, coercivity, and first, third and fifth harmonic amplitudes. The properties were extracted from the voltage measured across the detection coil and incorporate the magnetic influence of the soft iron core, but with the effect of air gap variation between pole piece and sample kept to a controlled range. Results were compared to a micromagnetic model for the effect of biaxial stress on hysteresis and on magnetic properties. The micromagnetic model is a modified version of a model previously employed by Schneider et al. The experimental remanence variation due to biaxial stress compared very well to the predictions of the model. Furthermore, the model predict,s and experiment bears out, that the remanence with the field along one stress axis minus the remanence with the field along the other stress axis falls in a straight-line band of values when plotted against the difference of the two stresses. This suggests …
Date:
December 31, 1993
Creator:
Sablik, M.J.; Burkhardt, G.L. & Kwun, H.
Object Type:
Report
System:
The UNT Digital Library
Application of rotating contactor to natural gas processing
The objective of to evaluate the potential of rotating gas-liquid contactors for natural gas processing by expanding the currently available database. This expansion is leading to commercial demonstration of this technology to environments representative of those typically encountered in the natural gas processing industry. Operational and reliability concerns will be addressed while generating pertinent engineering data relating to the mass-transfer process.
Date:
December 31, 1993
Creator:
Lee, A. L. & Semrau, J. T.
Object Type:
Article
System:
The UNT Digital Library
Application of the Resonating Hartree-Fock Theory to the Lipkin Model
In order to make clear essential features of the resonating Hartree-Fock (Res HF) theory for a Fermion system with large quantum fluctuations and to show its superiority over the usual HF theory, the authors apply it to the exactly solvable Lipkin model. They use a new direct optimization algorithm to optimize orbitals in nonorthogonal Slater determinants (S-dets) in a Res HF wave function. For the sake of simplicity, they assume a Res HF wave function to be superposed by two S-dets {vert_bar}g{sub 1}> {vert_bar}g{sub 2}> which give corresponding two local energy minima of monopole deformation. They make the self-consistent Res HF calculation so as to minimize the energy functional including up to the second order variation. The Res HF ground state generated with only two S-dets brings the ground state energy very near to the exact one and then explains most of the ground state correlation energy.
Date:
December 31, 1993
Creator:
Nishiyama, Seiya
Object Type:
Report
System:
The UNT Digital Library
Applications of molten salts in reactive metals processing
Pyrochemical processes using molten salts provide a unique opportunity for the extraction and refining of many reactive and valuable metals either directly from the beneficiated ore or from other process effluent that contain reactive metal compounds. This research program is aimed at developing a process for the production and recovery of reactive and valuable metals, such as zinc, tin, lead, bismuth and silver, in a hybrid reactor combining electrolytic production of the calcium reductant and in-situ utilization of this reductant for pyrochemical reduction of the metal compounds, such as halide or oxides. The process is equally suitable for producing other low melting metals, such as cadmium and antimony. The cell is typically operated below 1000C temperature. Attempts have been made to produce silver, lead, bismuth, tin and cerium by calciothermic reduction in a molten salt media. In a separate effort, calcium has been produced by an electrolytic dissociation of lime in a calcium chloride medium. The most important characteristic of the hybrid technology is its ability to produce metals under ``zero-waste`` conditions.
Date:
December 31, 1993
Creator:
Mishra, B.; Olson, D. L. & Averill, W. A.
Object Type:
Article
System:
The UNT Digital Library
Applications of the ARGUS code in accelerator physics
ARGUS is a three-dimensional, electromagnetic, particle-in-cell (PIC) simulation code that is being distributed to U.S. accelerator laboratories in collaboration between SAIC and the Los Alamos Accelerator Code Group. It uses a modular architecture that allows multiple physics modules to share common utilities for grid and structure input., memory management, disk I/O, and diagnostics, Physics modules are in place for electrostatic and electromagnetic field solutions., frequency-domain (eigenvalue) solutions, time- dependent PIC, and steady-state PIC simulations. All of the modules are implemented with a domain-decomposition architecture that allows large problems to be broken up into pieces that fit in core and that facilitates the adaptation of ARGUS for parallel processing ARGUS operates on either Cray or workstation platforms, and MOTIF-based user interface is available for X-windows terminals. Applications of ARGUS in accelerator physics and design are described in this paper.
Date:
December 31, 1993
Creator:
Petillo, J. J.; Mankofsky, A.; Krueger, W. A.; Kostas, C.; Mondelli, A. A. & Drobot, A. T.
Object Type:
Article
System:
The UNT Digital Library
Applications of the EBR-II Probabilistic Risk Assessment
A Probabilistic Risk Assessment (PRA) of the Experimental Breeder Reactor 11 (EBR-11), a Department of Energy (DOE) Category A research reactor, has recently been completed at Argonne National Laboratory (ANL), and has been performed with close collaboration between PRA analysts and engineering and operations staff. A product of this Involvement of plant personnel has been a excellent acceptance of the PRA as a tool, which has already resulted In a variety of applications of the EBR-11 PRA. The EBR-11 has been used in support of plant hardware and procedure modifications and In new system design work. A new application in support of the refueling safety analysis will be completed in the near future.
Date:
December 31, 1993
Creator:
Roglans, J.: Ragland, W. A. & Hill, D. J.
Object Type:
Report
System:
The UNT Digital Library
An approach to establishing cooperative R&D projects with Russian Institutes
An important part of technology exchange between the US and the former Soviet Union is the identification and implementation of cooperative projects that benefit both Russia and the US. The US Department of Energy and its laboratories have established an approach to identify potential technologies that can contribute to solving US environmental problems and to establish projects for enhancing technology development. This approach consists of screening technologies for US applications, conducting small-scale pilot projects with Russian scientists to evaluate the validity of mechanisms for larger projects, helping develop direct communication between US and Russian scientists who are developing these technologies, and implementing major projects in specific technology development areas. A recent example of this approach is the initiation of projects between the Khlopin Radium Institute and DOE through Sandia National Laboratories and SAIC. This effort has resulted in not only enhanced technology for the US but has also provided an example for future cooperative projects.
Date:
December 31, 1993
Creator:
Hunter, T.; Albert, T.; Fryberger, T. & Romanovsky, V.
Object Type:
Article
System:
The UNT Digital Library
Archaeological investigations at a toolstone source area and temporary camp: Sample Unit 19-25, Nevada Test Site, Nye County, Nevada. Technical report No. 77
Archaeological investigations were initiated at Sample Unit 19--25 to retrieve information concerning settlement and subsistence data on the aboriginal hunter and gatherers in the area. Studies included collection and mapping of 35.4 acres at site 26NY1408 and excavation and mapping of 0.02 acres at site 26NY7847. Cultural resources include two rock and brush structures and associated caches and a large lithic toolstone source area and lithic artifact scatter. Temporally diagnostic artifacts indicate periodic use throughout the last 12,000 years; however dates associated with projectile points indicate most use was in the Middle and Late Archaic. Radiocarbon dates from the rock and brush structures at site 26NY7847 indicate a construction date of A.D. 1640 and repair between A.D. 1800 and 1950 for feature 1 and between A.D. 1330 and 1390 and repair at A.D. 1410 for feature 2. The dates associated with feature 2 place its construction significantly earlier than similar structures found elsewhere on Pahute Mesa. Activity areas appear to reflect temporary use of the area for procurement of available lithic and faunal resources and the manufacture of tools.
Date:
December 31, 1993
Creator:
Jones, R. C.; DuBarton, A.; Edwards, S.; Pippin, L. C. & Beck, C. M.
Object Type:
Report
System:
The UNT Digital Library