Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, September 1--November 30, 1994 (open access)

Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, September 1--November 30, 1994

The objective of this study is to obtain data on the rates and the extent of sulfation reactions involving partially sulfided calcium-based sorbents, and oxygen as well as sulfur dioxide, at operating conditions closely simulating those prevailing in the second stage (combustor) of Advanced Two-Stage Pressurized Fluidized-Bed Combustors (PFBC). In these systems the CO{sub 2} partial pressure generally exceeds the equilibrium value for calcium carbonate decomposition. Therefore, calcium sulfate is produced through the reactions between SO{sub 2} and calcium carbonate as well as the reaction between calcium sulfide and oxygen. To achieve this objective, the rates of reaction involving SO{sub 2} and oxygen (gaseous reactant); and calcium sulfide and calcium carbonate (solid reactants), will be determined by conducting tests in a pressurized thermogravimetric analyzer (HPTGA) unit. The effects of sorbent type, sorbent particle size, reactor temperature and pressure; and O{sub 2} as well as SO{sub 2} partial pressures on the sulfation reactions rate will be determined. During this quarter, samples of the selected limestone and dolomite were sulfided in the fluidized-bed reactor. These tests were conducted in both calcining and non-calcining operating conditions to produce partially-sulfided sorbents containing calcium oxide and calcium carbonate, respectively. These samples which represent the carbonizer …
Date: December 31, 1994
Creator: Abbasian, Javad; Hill, Andy; Wangerow, James R. & Honea, Franklin I.
Object Type: Report
System: The UNT Digital Library
Disilene Addition to C{sub 70} (open access)

Disilene Addition to C{sub 70}

Semiempirical and ab initio Hartree Fock computational results indicate that the highly reactive dienophile tetramethyldisilene, Me{sub 2}Si=SiMe{sub 2}, is an excellent candidate for a novel functionalization of the equator of C{sub 70} via a [2+4] cycloaddition to the 21, 22, 23, 42 carbons. Thermal or photochemical generation of tetramethyldisilene in the presence of C{sub 70} results in similar complex mixtures in which the major product appears to be that of [2+2] cycloaddition to the 7,8 carbons of C{sub 70}. A minor product clearly results from [2+2] cycloaddition to the 1,9 carbons. Both of these products are hydrolytically unstable and are converted nonspecifically to mixtures of 1,9- and 7,8-C{sub 70}H{sub 2} which are also present in HPLC traces of the reaction mixtures.
Date: December 31, 1994
Creator: Jacobs, S. J.; Cahill, P. A. & Rohlfing, C. M.
Object Type: Article
System: The UNT Digital Library
Mass transport through polycrystalline microstructures (open access)

Mass transport through polycrystalline microstructures

Mass transport properties are important in polycrystalline materials used as protective films. Traditionally, such properties have been studied by examining model polycrystalline structures, such as a regular array of straight grain boundaries. However, these models do not account for a number of features of real grain ensembles, including the grain size distribution and variations in grain shape. In this study, a finite difference scheme is developed to study transient and steady-state mass transport through realistic two dimensional polycrystalline microstructures. Comparisons with the transport properties of traditional model microstructures provide regimes of applicability of such models. The effects of microstructural parameters such as average grain size are examined.
Date: December 31, 1994
Creator: Swiler, T. P.; Holm, E. A.; Young, M. F. & Wright, S. A.
Object Type: Report
System: The UNT Digital Library
Further studies of the effects of oxidation on the surface properties of coal and coal pyrite (open access)

Further studies of the effects of oxidation on the surface properties of coal and coal pyrite

The objective of this research was to investigate the oxidation behavior of coal and coal pyrite and to correlate the changes in the surface properties induced by oxidation, along with the intrinsic physical and chemical properties of these organic and inorganic materials, with the behavior in physical coal cleaning processes. This provide more fundamental knowledge for understanding the way in which different factors interact in a medium as heterogeneous as coal. Fourteen coal samples of different ranks ranging from high to medium sulfur content were studied by dry oxidation tests at different temperatures and humidities, and by wet oxidation tests using different oxidizing agents. The concentration of surface oxygen functional groups was determined by ion-exchange methods. The changes in the coal composition with oxidation were analyzed by spectroscopic techniques. The wettability of as-received and oxidized coal and coal pyrite samples was assessed by film flotation tests. The electrokinetic behavior of different coals and coal pyrite samples was studied by electrokinetic tests using electrophoresis. Possible oxidation mechanisms have been proposed to explain the changes on the coal surface induced by different oxidation treatments.
Date: December 31, 1994
Creator: Herrera, Miguel Nicholas
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Flat panel display development activities at Sandia National Laboratories (open access)

Flat panel display development activities at Sandia National Laboratories

The flat panel display development activities underway at Sandia National Laboratories are described. Research is being conducted in the areas of glass substrates, phosphors, large area processes, and electron emissions. Projects are focused on improving process yield, developing large area processes, and using modeling techniques to predict design performance.
Date: December 31, 1994
Creator: DiBello, E. G.; Worobey, W.; Burchett, S.; Hareland, W.; Felter, T. & Mays, B.
Object Type: Article
System: The UNT Digital Library
Oxygen stoichiometry and its influence on superconductivity in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} (open access)

Oxygen stoichiometry and its influence on superconductivity in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}

Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} (2212) was synthesized from freeze-dried precursors. The oxygen content of 2212 was determined as a function of temperature and oxygen partial pressure and the variation of Tc with oxygen content was determined. It was found that 2212 without excess oxygen (x = 0) is superconducting. This points to the role of the (Bi-O){sub {infinity}} layers as a source for holes in 2212. Four probe resistivity measurements were also performed on 2212. The nature of oxygen intercalation and oxygen removal in 2212 was studied by thermogravimetry and resistivity. It was also found that samples of 2212 with the same oxygen content had different {Tc}`s depending on thermal history. This difference in {Tc} is thought to arise from oxygen occupying different sites in the lattice while maintaining the same total oxygen content.
Date: December 31, 1994
Creator: Krishnaraj, P.; Lelovic, M.; Eror, N. G. & Balachandran, U.
Object Type: Report
System: The UNT Digital Library
The role of the LLNL Atmospheric Release Advisory Capability in a FRMAC response to a nuclear power plant incident (open access)

The role of the LLNL Atmospheric Release Advisory Capability in a FRMAC response to a nuclear power plant incident

The Federal Radiological Emergency Response Plan (FRERP) can provide several emergency response resources in response to a nuclear power plant (NPP) accident if requested by a state or local agency. The primary FRERP technical resources come from the US Department of Energy`s (DOE) Federal Radiological Monitoring and Assessment Center (FRMAC). Most of the FRMAC assets are located at the DOE Remote Sensing Laboratory (RSL) at Nellis Air Force Base, Las Vegas, Nevada. In addition, the primary atmospheric dispersion modeling and dose assessment asset, the Atmospheric Release Advisory Capability (ARAC) is located at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. In the early stages of a response, ARAC relies on its automatic worldwide meteorological data acquisition via the Air Force Global Weather Center (AFGWC). The regional airport data are supplemented with data from on-site towers and sodars and the National Oceanographic & Atmospheric Administration`s (NOAA) field-deployable real-time rawinsonde system. ARAC is prepared with three-dimensional regional-scale diagnostic dispersion model to simulate the complex mixed fission product release from a reactor accident. The program has been operational for 18 years and is presently developing its third generation system. The current modernization includes faster central computers, a new site workstation system. The current …
Date: December 31, 1994
Creator: Baskett, R. L.; Sullivan, T. J.; Ellis, J. S. & Foster, C. S.
Object Type: Article
System: The UNT Digital Library
Study of parity and time reversal violation in neutron-nucleus interactions (open access)

Study of parity and time reversal violation in neutron-nucleus interactions

The parity and time-reversal symmetries can be studies in neutron-nucleus interactions. Parity non-conserving asymmetries have been observed for many p-wave resonances in a compound nucleus and measurements were performed on several nuclei in the mass region of A{approximately}100 and A{approximately}230. The statistical model of the compound nucleus provides a theoretical basis for extracting mean-squared matrix elements from the experimental asymmetry data, and for interpreting the mean-squared matrix elements. The constraints on the weak meson-exchange couplings calculated from the compound-nucleus asymmetry data agree qualitatively with the results from few-body and light-nuclei experiments. The tests of time-reversal invariance in various experiments using thermal, epithermal and MeV neutrons are being developed.
Date: December 31, 1994
Creator: Yen, Yi-Fen; Bowman, J. D.; Frankle, C. M. & Crawford, B. E.
Object Type: Article
System: The UNT Digital Library
Manufacture and testing of the superconducting wire and cable for the RHIC dipoles and quadrupoles (open access)

Manufacture and testing of the superconducting wire and cable for the RHIC dipoles and quadrupoles

Production of superconducting wire and cable for RHIC dipoles and quadrupoles is now complete. This report presents final statistics generated during the manufacture and testing of this cable.
Date: December 31, 1994
Creator: Greene, A. F.; Garber, M. G.; Ghosh, A. K.; McChesney, D.; Morgillo, A.; Shah, R. et al.
Object Type: Article
System: The UNT Digital Library
Accelerator-based systems for plutonium destruction and nuclear waste transmutation (open access)

Accelerator-based systems for plutonium destruction and nuclear waste transmutation

Accelerator-base systems are described that can eliminate long-lived nuclear materials. The impact of these systems on global issues relating to plutonium minimization and nuclear waste disposal can be significant. An overview of the components that comprise these systems is given, along with discussion of technology development status and needs. A technology development plan is presented with emphasis on first steps that would demonstrate technical performance.
Date: December 31, 1994
Creator: Arthur, E. D.
Object Type: Article
System: The UNT Digital Library
Gamma-ray measurements at the WNR white neutron source (open access)

Gamma-ray measurements at the WNR white neutron source

Photon production data have been acquired in the incident neutron energy range, 1 < E{sub n} < 400 MeV, for a number of target nuclei, gamma-ray energy ranges, and reactions, using the continuous-energy neutron beam of the WNR facility at Los Alamos. Gamma-ray production measurements using high resolution Ge detectors have been employed for gamma-rays in the energy range, 0.1 < E{sub {gamma}} < 10 MeV. These measurements allow identification of reactions from the known energies of the gamma-ray transitions between low-lying states in the final nucleus. Some of the targets studied include: N, O, Al, Na, {sup 56}Fe, and {sup 207,208}Pb. These data are useful both for testing nuclear reaction models at intermediate energies and for numerous applied purposes. BGO detectors do not have the good energy resolution of Ge detectors, but have much greater detection efficiency for gamma rays with energies greater than a few MeV. We have used an array of 5 BGO detectors to measure cross sections and angular distributions for photon production from C and N. A large, well-shielded BGO detector has been used to measure fast neutron capture in the giant resonance region with a maximum gamma-ray energy of 52 MeV. We present results …
Date: December 31, 1994
Creator: Nelson, R. O.; Wender, S. A. & Mayo, D. R.
Object Type: Article
System: The UNT Digital Library
Proceedings of the workshop on future hadron facilities in the US (open access)

Proceedings of the workshop on future hadron facilities in the US

This report discusses the following topics on future hadron facilities: Workshop on future hadron facilities in the US; 30 {times} 30 TeV-summary report; A high luminosity, 2 {times} 2 TeV collider in the tevatron tunnel; magnets working group; cryogenics discussion; vacuum report; antiproton source production; injector working group; interaction region working group; lattice/beam dynamics working group; LEBT for high-luminosity colliders; some notes on long-range beam-beam effects for the 2TeV collider; synchrotron radiation masks for high energy proton accelerators. Emittance preservation in a proton synchrotron; beam-beam interaction effects on betatron tunes; analytic solutions for phase trombone modules; and chromatic corrections of RHIC when one or two insertions is at {Beta}* = 0.5m.
Date: December 31, 1994
Creator: unknown
Object Type: Article
System: The UNT Digital Library
Optical properties of fractal nanocomposites (open access)

Optical properties of fractal nanocomposites

Optical prossesses in nanostructured fractal composites are shown to be strongly enhanced. The enhancement occurs because of a localization of dipolar eigenmodes in subwavelength areas.
Date: December 31, 1994
Creator: Markel, V. A.; Kim, W.; Armstrong, R.; Shalaev, V. & Stechel, E. B.
Object Type: Article
System: The UNT Digital Library
Buried Waste Integrated Demonstration lessons learned: 1993 technology demonstrations (open access)

Buried Waste Integrated Demonstration lessons learned: 1993 technology demonstrations

An integrated technology demonstration was conducted by the Buried Waste Integrated Demonstration (BWID) at the Idaho National Engineering Laboratory Cold Test Pit in the summer of 1993. This program and demonstration was sponsored by the US Department of Energy Office of Technology Development. The demonstration included six technologies representing a synergistic system for the characterization and retrieval of a buried hazardous waste site. The integrated technology demonstration proved very successful and a summary of the technical accomplishments is presented. Upon completion of the integrated technology demonstration, cognizant program personnel participated in a lessons learned exercise. This exercise was conducted at the Simplot Decision Support Center at Idaho State University and lessons learned activity captured additional information relative to the integration of technologies for demonstration purposes. This information will be used by BWID to enhance program planning and strengthen future technology demonstrations.
Date: December 31, 1994
Creator: Kostelnik, K. M. & Owens, K. J.
Object Type: Article
System: The UNT Digital Library
A comparison of NH{sub 3} point monitoring and diode laser based path integrated measurements (open access)

A comparison of NH{sub 3} point monitoring and diode laser based path integrated measurements

Measurements made using two different types of ammonia monitors during a two-month field study in the summer of 1994 are discussed. The first was a diode-laser based open path monitor designed for automated operation in an industrial environment. The second is a monitoring analyzer based on thermal decomposition of ammonia to NO and subsequent analysis by O{sub 3}-NO chemiluminescence. The two monitors provided consistent measurements of ammonia concentration during weeks of continuous unattended operation.
Date: December 31, 1994
Creator: Goldstein, N.; Richtsmeier, S. C.; Lee, J.; Bien, F.; Fetzer, G. J. & Groff, K. W.
Object Type: Report
System: The UNT Digital Library
The interactions of high-energy, highly charged Xe ions with buckyballs (open access)

The interactions of high-energy, highly charged Xe ions with buckyballs

Ionization and fragmentation have been measured for C{sub 60} molecules bombarded by highly charged (up to 35+) xenon ions with energies ranging up to 625 MeV. The observed mass distribution of positively charged fragments is explained in terms of a theoretical model indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. Preliminary results of measurements on VUV photons emitted in these interactions are also presented.
Date: December 31, 1994
Creator: Ali, R.; Berry, H. G. & Cheng, S.
Object Type: Report
System: The UNT Digital Library
Energetic particle destabilization of shear Alfven waves in stellarators and tokamaks (open access)

Energetic particle destabilization of shear Alfven waves in stellarators and tokamaks

An important issue for ignited devices is the resonant destabilization of shear Alfven waves by energetic populations. These instabilities have been observed in a variety of toroidal plasma experiments in recent years, including: beam-destabilized toroidal Alfven instabilities (TAE) in low magnetic field tokamaks, ICRF destabilized TAE`s in higher field tokamaks, and global Alfven instabilities (GAE) in low shear stellarators. In addition, excitation and study of these modes is a significant goal of the TFIR-DT program and a component of the ITER physics tasks. The authors have developed a gyrofluid model which includes the wave-particle resonances necessary to excite such instabilities. The TAE linear mode structure is calculated nonperturbatively, including many of the relevant damping mechanisms, such as: continuum damping, non-ideal effects (ion FLR and electron collisionality), and ion/electron Landau damping. This model has been applied to both linear and nonlinear regimes for a range of experimental cases using measured profiles.
Date: December 31, 1994
Creator: Spong, D. A.; Carreras, B. A.; Hedrick, C. L.; Leboeuf, J. N. & Weller, A.
Object Type: Report
System: The UNT Digital Library
Status of nuclear data for ITER applications (open access)

Status of nuclear data for ITER applications

As the development of a near-term fusion reactor, such as the International Thermonuclear Experimental Reactor (ITER), enters the engineering design activity phase, one of the essential elements leading to the successful design, construction and operation of such a reactor is nuclear data. High quality nuclear data for all reactor materials relevant to ITER will be required in order to assess the nuclear performance, radiation damage, and safety and environmental aspects of all reactor components. In this paper the authors review the current ITER design, noting which materials and associated nuclear data are important in the various reactor components. They also review the contents of the Fusion Evaluated Nuclear Data Library (FENDL) accepted for use by ITER, and identify materials for which nuclear data improvements are required.
Date: December 31, 1994
Creator: Larson, D. C.; Cheng, E. T.; Mann, F. M. & Saji, G.
Object Type: Article
System: The UNT Digital Library
Indirectly driven targets for ignition (open access)

Indirectly driven targets for ignition

Both Los Alamos and Lawrence Livermore Laboratories have studied capsule and laser driven target designs for the National Ignition Facility. The current hohlraum design is a 2.76mm radius, 9.5mm long gold cylinder with 1.39mm radius laser entrance holes covered by 1{mu}m thick plastic foils. Laser beams strike the inside cylinder wall from two separate cones with a peak power less than 400 TW. The problem with a pressure pulse caused by wall plasma stagnating on axis has been overcome by filling the hohlraum with gas. Currently this is equi-molar hydrogen-helium gas at 0.83 mg/cc density. One capsule uses a 160 {mu}m plastic ablator doped with oxygen and bromine surrounding an 80 {mu}m thick DT ice layer with an inner radius of 0.87 mm. Los Alamos integrated calculations of the hohlraum and this capsule using 1.4 MJ of laser energy achieve yields of 4.9 MJ using LTE atomic physics, and 3.5 MJ with non-LTE. This confirms Livermore calculations of ignition. For radiation driven implosions, a beryllium ablator offers a viable alternative to plastic. It is strong enough to contain high DT pressures. Copper, soluble at required levels, is an excellent dopant to add opacity. A beryllium capsule with a 155 {mu}m …
Date: December 31, 1994
Creator: Wilson, D. C. & Krauser, W. J.
Object Type: Report
System: The UNT Digital Library
Vacancy related defects in thin film Pb(ZrTi)O{sub 3} materials (open access)

Vacancy related defects in thin film Pb(ZrTi)O{sub 3} materials

Positron annihilation techniques have been applied to characterize vacancy-related defects in ferroelectric thin film structures. Variable energy positron beam measurements were carried out on doped and undoped Pb(ZrTi)O{sub 3} (PZT) samples subjected to different post-deposition cool down and anneal conditions. The PZT was deposited by sol-gel with either with platinum or RuO{sub 2} electrodes, or by laser ablation with La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrodes. The RuO{sub 2} and La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrode samples showed a smaller S-parameter compared to those deposited with Pt electrodes consistent with an improved PZT layer quality. For laser ablated samples cooled in a reducing ambient an increase in S-parameter for both the PZT and La{sub 0.5}Sr{sub 0.5}CoO{sub 3} layers was observed indicating an increase in neutral or negatively charged open-volume defects.
Date: December 31, 1994
Creator: Krishnan, A.; Keeble, D. J.; Ramesh, R.; Warren, W. L.; Tuttle, B. A.; Pfeffer, R. L. et al.
Object Type: Report
System: The UNT Digital Library
Long-Baseline Neutrino Oscillation Experiments (open access)

Long-Baseline Neutrino Oscillation Experiments

There is no unambiguous definition for long baseline neutrino oscillation experiments. The term is generally used for accelerator neutrino oscillation experiments which are sensitive to {Delta}m{sup 2} < 1.0 eV{sup 2}, and for which the detector is not on the accelerator site. The Snowmass N2L working group met to discuss the issues facing such experiments. The Fermilab Program Advisory Committee adopted several recommendations concerning the Fermilab neutrino program at their Aspen meeting immediately prior to the Snowmass Workshop. This heightened the attention for the proposals to use Fermilab for a long-baseline neutrino experiment at the workshop. The plan for a neutrino oscillation program at Brookhaven was also thoroughly discussed. Opportunities at CERN were considered, particularly the use of detectors at the Gran Sasso laboratory. The idea to build a neutrino beam from KEK towards Superkamiokande was not discussed at the Snowmass meeting, but there has been considerable development of this idea since then. Brookhaven and KEK would use low energy neutrino beams, while FNAL and CERN would plan have medium energy beams. This report will summarize a few topics common to LBL proposals and attempt to give a snapshot of where things stand in this fast developing field.
Date: December 31, 1994
Creator: Crane, Dan & Goodman, Maury
Object Type: Article
System: The UNT Digital Library
The hard truth (open access)

The hard truth

In the Bayesian methodology, the posterior probability combines uncertainty about prior knowledge, and available data about alternative models of reality. The posterior quantifies the degree of certainty one has in inferring the truth in terms of those models. We propose a method to determine the reliability of a specific feature of a Bayesian solution. Our approach is based on an analogy between the negative logarithm of the posterior and a physical potential. This analogy leads to the interpretation of gradient of this potential as a force that acts on the model. As model parameters are perturbed from their maximum a posteriori (MAP) values, the strength of the restoring force that drives them back to the MAP solution is directly related to the reliability of those parameter estimates. The correlations between the uncertainties of parameter estimates can be elucidated.
Date: December 31, 1994
Creator: Hanson, K. M. & Cunningham, C. S.
Object Type: Article
System: The UNT Digital Library
High surface area, high permeability carbon monoliths (open access)

High surface area, high permeability carbon monoliths

The goal of this work is to prepare carbon monoliths having precisely tailored pore size distribution. Prior studies have demonstrated that poly(acrylonitrile) can be processed into a precursor having tailored macropore structure. Since the macropores were preserved during pyrolysis, this synthetic process provided a route to porous carbon having macropores with size =0.1 to 10{mu}m. No micropores of size <2 nm could be detected in the carbon, however, by nitrogen adsorption. In the present work, the authors have processed a different polymer, poly(vinylidene chloride) into a macroporous precursor, Pyrolysis produced carbon monoliths having macropores derived from the polymer precursor as well as extensive microporosity produced during the pyrolysis of the polymer. One of these carbons had BET surface area of 1,050 m{sup 2}/g and about 1.2 cc/g total pore volume, with about 1/3 of the total pore volume in micropores and the remainder in 1{mu}m macropores. No mesopores in the intermediate size range could be detected by nitrogen adsorption. Carbon materials having high surface area as well as micron size pores have potential applications as electrodes for double layer supercapacitors containing liquid electrolyte, or as efficient media for performing chemical separations.
Date: December 31, 1994
Creator: Lagasse, R. R. & Schroeder, J. L.
Object Type: Article
System: The UNT Digital Library
Tau as a probe for new physics (open access)

Tau as a probe for new physics

The usage of polarimetry and spin-correlation tests to determine the complete Lorenz structure of the tau lepton`s charged and neutral- current couplings is reviewed. The emphasis is on tests for ``something`` in a (V-A)+ ``something`` structure in J{sup charged} Lepton current, so as to bound the scales {lambda} for ``new physics`` such as arising from tau weak magnetism, weak electricity, and/or second-class currents. Tests for T and for CP violation are discussed.
Date: December 31, 1994
Creator: Nelson, C. A.
Object Type: Article
System: The UNT Digital Library