UNT Libraries Government Documents Department - 1,007 Matching Results

Search Results

Calculating solvation forces and adsorption in complex geometries with a finite element-nonlocal density functional theory method

Description: Density functional theories (DFT) for inhomogeneous fluids have been used profitably to study the structure of fluids near surfaces, and to predict solvation forces, adsorption isotherm, and a variety of surface induced phase transitions. However, in nearly all cases, only geometries with 2 symmetry planes (e.g. fluid near a uniform planar interface or a fluid in a uniform cylindrical pore) have been considered. In this paper the authors discuss the generalization of the DFT to cases with either one or no symmetry planes. They present their computational approach, as well as results for charged cylindrical polyelectrolytes and planar surfaces with inhomogeneous chemistry.
Date: June 14, 1998
Creator: Douglas Frink, L.J. & Salinger, A.G.

Calculation of thermal diffuse scattering

Description: The authors developed a computer program to calculate the thermal diffuse scattering (TDS) intensity distribution for single crystal specimens in a diffractometer with no energy analysis. They assumed that the phonon frequencies are approximated by those of elastic waves and that the elastic constants, density and lattice parameters of the system under study are known. The results of the calculations were compared to experimental data obtained for single crystals of Si, diamond and NiAl at the Wide Angle neutron Diffractometer at the HFIR at Oak Ridge National Laboratory. Excellent agreement was found between the calculations and the experimental observations.
Date: July 14, 1997
Creator: Wakabayashi, N.; Nicklow, R.M.; Child, H.R.; Smith, H.G.; Fernandez-Baca, J.A.; Katano, S. et al.

CALOR as a Single Code Including a Modular Version of HETC

Description: The major components of CALOR are HETC, MORSE, EGS4, EGS4PREP, and SPECT, working sequentially on calorimeter detector for high energy physics, experimental analysis, or shielding studies. An effort to combine the components into a single code is described. The new code is modular in nature. For example, one may run only HETC and MORSE. In addition, HETC itself has become modular and may be run in three energy options--up to 2.5 GeV, 15 GeV, and 20 TeV. The size of the low-energy option of HETC is less than 40% of the original HETC. A great advantage of the new code is the elimination of three huge files for passing information from one component to another.
Date: September 14, 1998
Creator: Fu, C.Y. & Gabriel, T.A.

Campaign Financing: Highlights and Chronology of Current Federal Law

Description: Current law governing financial activity of campaigns for federal office is based on two principal statutes: the Federal Election Campaign Act (FECA) of 1971, as amended in 1974, 1976, and 1979, and the Revenue Act of 1971. These laws were enacted to remedy widely perceived shortcomings of existing law, the Corrupt Practices Act of 1925, and in response to reports of campaign finance abuses over the years, culminating in the 1972-1974 Watergate scandal. This report provides a summary of major provisions of federal law and a chronology of key legislative and judicial actions.
Date: June 14, 1999
Creator: Cantor, Joseph E.

Carbon reduction in uranium alloys utilizing hafnium additions

Description: With increasing environmental concerns regarding the handling and storage of uranium waste, recycling previously used material is becoming exceedingly more important. Carbon is one of the primary trace impurities that builds up in uranium with repeated use. The goal of this study is to reduce carbon in recycled uranium during the casting process to carbon levels associated with virgin uranium derbies. Vacuum-induction casting experiments have demonstrated that hafnium (Hf) additions to unalloyed uranium (U) reduce carbon (C) levels by approximately 80% in up to 6.0 in. in depth in 5 {times} 7 {times} 15 in. (width {times} depth {times} thickness) book mold castings. Analytic modeling of the solidification process was initiated to compare the calculated/predicted thermal profile to the actual experimentally measured temperatures. Temperature profile predictions matched the experimental values at the top of the casting and accurately determined that the predominant heat loss is out of the bottom of the book mold assembly. However, the model overpredicts the temperature half way down the length of the casting. The boundary heat transfer coefficient at the bottom of the casting needs to be more accurately simulated. 4 refs., 5 figs., 3 tabs.
Date: August 14, 1990
Creator: Mackiewicz-Ludtka, G.; Pullen, W.C.; Henderson, C.A. (Oak Ridge Y-12 Plant, TN (USA)); Chu, W. & Wendel, M.W. (Oak Ridge Gaseous Diffusion Plant, TN (USA))

The Carnol process system for CO2 mitigation and methanol production

Description: The feasibility of an alternative CO{sub 2} mitigation system and a methanol production process is investigated. The Carnol system has three components: (1) a coal fired power plant supplying flue gas CO{sub 2} to, (2) the Carnol process which converts the CO{sub 2} with hydrogen from natural gas to methanol which is used, (3) as a fuel component in the automotive sector. For the methanol production process alone, up to 100% CO{sub 2} emission reduction can be achieved while for the entire system up to 65% CO{sub 2} emission reduction can be obtained. The Carnol system is technically feasible and economically competitive with alternative CO{sub 2} disposal systems for coal fired power plants. The Carnol process is estimated to be economically attractive compared to the current market price of methanol, especially if credit can be taken for the carbon as a marketable coproduct.
Date: August 14, 1995
Creator: Steinberg, M.

Case study of isosurface extraction algorithm performance

Description: Isosurface extraction is an important and useful visualization method. Over the past ten years, the field has seen numerous isosurface techniques published leaving the user in a quandary about which one should be used. Some papers have published complexity analysis of the techniques yet empirical evidence comparing different methods is lacking. This case study presents a comparative study of several representative isosurface extraction algorithms. It reports and analyzes empirical measurements of execution times and memory behavior for each algorithm. The results show that asymptotically optimal techniques may not be the best choice when implemented on modern computer architectures.
Date: December 14, 1999
Creator: Sutton, P M; Hansen, C D; Shen, H & Schikore, D

CASIM input parameters for various materials

Description: During the past year, the computer program CASIM has been placed in a common area from which copies can be obtained by a wide array of users. The impetus for this arrangement was the need to have a standard code that could be maintained and transported to other platforms. In addition, an historical record would be kept of each version as the program evolved. CASIM requires a series of parameters (input by the user) that describe the medium in which the cascade develops. Presently a total of 9 materials can be defined. Occasions arise when one needs to know the properties of materials (elements, compounds, and mixtures) that have not been defined. Because it is desirable to have a uniform set of values for all CASIM users, this note presents a methodology for obtaining the input parameters for an arbitrary material. They are read in by the Subroutine CASIM{underscore}PROG from the user supplied file CASIM.DAT.
Date: July 14, 1994
Creator: Malensek, A. J. & Elwyn, A. J.

Catalysts and electrocatalysts for the selective oxidation of propylene. Annual report

Description: This paper presents a summary of the status of the work on three topics: synthesis and characterization of the Mn doped bismuth vanadates; electrode studies; and oxygen permeation. The authors have made a detailed study of manganese doped bismuth vanadates with the general composition Bi{sub 2}V{sub 1{minus}x}Mn{sub x}O{sub 5.5{minus}{delta}}. The phase diagram of Bi{sub 2}V{sub 1{minus}x}Mn{sub x}O{sub 5.5{minus}{delta}} has been investigated by diffraction and thermal analysis and they have found that the tetragonal phase can be stabilized in the composition range 0.1 {le} x {le} 0.25. The have used ac impedance techniques to study the properties of some electrocatalysts. The objective was to investigate the utility of the technique for obtaining mechanistic information relevant to an electrocatalytic reactor. Initial studies were of oxygen activation on silver electrodes. Finally, they have constructed an apparatus for high temperature permeation measurements and studied one system, the defect perovskite oxide SrCo{sub 0.8}Fe{sub 0.2}O{sub 3{minus}{delta}} (SCFO), in detail. Important conclusions of the work are to confirm the high permeation rates at high temperature (a flux of 10{sup {minus}6} mol/sec cm{sup 2} is equivalent to 1 cm{sup 3}/min cm{sup 2}) and to demonstrate that the surface exchange kinetics were rate limiting for this material.
Date: February 14, 1995

Cathodic protection -- Rectifier 46

Description: This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive waste.
Date: June 14, 1995
Creator: Lane, W.M.

Cathodic protection -- Rectifier 47

Description: This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste.
Date: June 14, 1995
Creator: Lane, W.M.

Cattle Prices: Questions and Answers

Description: After 7 years of relatively high returns, cattle producers by 1994 were experiencing steeply falling prices--mainly caused by abundant supplies of cattle destined for U.S. feedlots. Record-high grain prices and dry pastures amplified the problem. Because of the lengthy biological cycle governing cattle production, large numbers will be coming onto the market for some time, as producers undertake the slow process of curtailing herd expansion.
Date: November 14, 1996
Creator: Becker, Geoffrey S.

Chapter 2: Genetic Variability in Nuclear Ribosomal and Chloroplast DNA in Utah (Juniperus Osteosperma) and Western (J. Occidentalis) Juniper (Cupressaceae): Evidence for Interspecific Gene Flow1

Description: Early studies of evolutionary change in chloroplast DNA indicated limited variability within species. This finding has been attributed to relatively low rates of sequence evolution and has been maintained as justification for the lack of intraspecific sampling in studies examining, relationships at the species level and above. However, documentation of intraspecific variation in cpDNA has become increasingly common and has been attributed in many cases to ''chloroplast capture'' following genetic exchange across species boundaries. Rleseberg and Wendel (1993) list 37 cases of proposed hybridization in plants that include intraspecific variation in cpDNA, 24 (65%) of which they considered to be probable instances of introgression. Rieseberg (1995) suspected that a review of the literature at that time would reveal over 100 cases of intraspecific variation in CPDNA that could be attributed to hybridization and introgression. That intraspecific variation in cpDNA is potentially indicative of hybridization is founded on the expectation that slowly evolving loci or genomes will produce greater molecular variation between than within species. In cases where a species is polymorphic for CPDNA and at least one of the molecular variants is diagnostic for a second species, interspecific hybridization is a plausible explanation. Incongruence between relationships suggested by cpDNA variation and those supported by other types of data (e.g., morphology or molecular data from an additional locus) provides additional support for introgression. One aspect of hybridization in both animals and plants that has become increasingly evident is incongruence in the phylogenetic and geographic distribution of cytoplasmic and nuclear markers. In most cases cytoplasmic introgression appears to be more pervasive than nuclear exchange. This discordance appears attributable to several factors including differences in the mutation rate, number of effective alleles, and modes of inheritance of cytoplasmic and nuclear loci. In addition, unidirectional introgression following an initial hybridization event can result in ...
Date: February 14, 1998
Creator: Terry, Randall G.; Tausch, Robin J. & Nowak, Robert S.

Characterization and optimization of sorbents utilized for emission control during coal gasification. Final report

Description: To overcome the shortage of components required for high temperature operation required by current IGCC and PFBC systems, researchers recently have decided that the power systems can be optimized within an operation temperature range of 343 to 538 C. The findings of this research work support the use of iron oxides as an efficient, disposable hot gas desulfurization sorbent candidate to meet the temperature range of 343 to 538 C to further optimize its application for hot gas desulfurization. A parametric study was performed to characterize the controlling parameters dominating the absorption process of hydrogen sulfide by waste iron oxide as a sorbent alternative within a stringent environment with the use of simulated KRW reducing gas. The major parameters studied for hot gas desulfurization with the use of waste iron oxide; mixed in coal ash and reacted with hot sulfurized gas; in hot gas stream include (1) dust cake permeability during heavy dust loading, (2) feasibility of dust cake removal with current back pulse cleaning technology, (3) the reaction temperature, (4) the space velocity of the gas stream. Based on the parametric testing performed on hot gas desulfurization and particulate filtration, the test results of this study indicate that the simultaneous operation of hot gas desulfurization and particulate filtration is feasible. The significant savings of capital investment, system operation and maintenance justify the use of iron oxides as an excellent candidate for hot gas cleanup.
Date: July 14, 1998
Creator: Huque, Z.; Mei, D. & Zhou, J.

Characterization equipment essential drawing plan

Description: The purpose of this document is to list the Characterization equipment drawings that are classified as Essential Drawings and Support Drawings. Essential Drawings: Are those drawings identified by the facility staff as necessary to directly support the safe operation of the facility or equipment (HNF 1997a). Support Drawings: Are those drawings identified by facility staff that further describe the design details of structures, systems, or components shown on essential drawings. (HNF 1997a) The Characterization equipment drawings identified in this report are deemed essential drawings as defined in HNF-PRO-242, Engineering Drawing Requirements (HNF 1997a). These drawings will be prepared, revised, and maintained per HNF-PRO-440, Engineering Document Change Control (HNF 1997b). All other Characterization equipment drawings not identified in this document will be considered General drawings until the Characterization Equipment Drawing Evaluation Report (Wilson 1998) is updated during fiscal year 1999. Trucks 1 and 2 drawings are not included in this revision of the essential drawing list due to uncertainty about future use.
Date: May 14, 1999
Creator: WILSON, G.W.

(Characterization of lignin peroxidases from Phanerochaete)

Description: Work has continued on characterizing the kinetics of lignin peroxidases and has now expanded to include the chemistry of Mn peroxidases. Progress in these two area in addition to the authors work on the molecular biology of lignin biodegradation is briefly described below. Copies of two reprints and one preprint which have resulted from the work are attached.
Date: November 14, 1990

Characterization of short pulse laser-produced plasmas at the Lawrence Livermore National Laboratory ultra short-pulse laser

Description: The K-shell emission from porous aluminum targets is used to infer the density and temperature of plasmas created with 800 nm and 400 nm, 140 fs laser light. The laser beam is focused to a minimum spot size of 5 {mu}m with 800 nm light and 3 {mu}m with 400 nm light, producing a normal incidence peak intensity of 10{sup 18} Watts/cm{sup 2}. A new 800 fs x-ray streak camera is used to study the broadband x-ray emission. The time resolved and time integrated x-ray emission implies substantial differences between the porous target and the flat target temperature.
Date: July 14, 1993
Creator: Shepherd, R.; Price, D.; White, W.; Osterheld, A.; Walling, R.; Goldstein, W. et al.

Characterization of Sputter Deposited Thin Film Scandate Cathodes for Miniaturized Thermionic Converter Applications

Description: We have successfully developed a method for fabricating scandate-based thermionic emitters in thin film form. The primary goal of our effort is to develop thin film emitters that exhibit low work fimction, high intrinsic electron emissivity, minimum thermal activation properties and that can be readily incorporated into a microgap converter. Our approach has been to incorporate BaSrO into a SqOq matrix using rf sputtering to produce thin films. Diode testing has shown the resulting films to be electron emissive at temperatures as low as 900 K with current densities of 0.1 mA.cm-2 at 1100 K and saturation voltages. We calculate an approximate maximum work function of 1.8 eV and an apparent emission constant (Richardson's constant, A*) of 36 mA.cm-2.K-2. Film compositional and structural analysis shows that a significant surface and subsurface alkaline earth hydroxide phase can form and probably explains the limited utilization and stability of Ba and its surface complexes. The flexibility inherent in sputter deposition suggests alternate strategies for eliminating undesirable phases and optimizing thin film emitter properties.
Date: December 14, 1998
Creator: King, D.B.; Ruffner, J.H. & Zavadil, K.R.