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Zone refining high-purity germanium

Description: The effects of various parameters on germanium purification by zone refining have been examined. These parameters include the germanium container and container coatings, ambient gas and other operating conditions. Four methods of refining are presented which reproducibly yield 3.5 kg germanium ingots from which high purity (vertical barN/sub A/ - N/sub D/vertical bar less than or equal to2 x 10/sup 10/ cm/sup -3/) single crystals can be grown. A qualitative model involving binary and ternary complexes of Si, O, B, and Al is shown to account for the behavior of impurities at these low concentrations.
Date: October 1, 1977
Creator: Hubbard, G.S.; Haller, E.E. & Hansen, W.L.

Zone refining of plutonium metal

Description: The purpose of this study was to investigate zone refining techniques for the purification of plutonium metal. The redistribution of 10 impurity elements from zone melting was examined. Four tantalum boats were loaded with plutonium impurity alloy, placed in a vacuum furnace, heated to 700{degrees}C, and held at temperature for one hour. Ten passes were made with each boat. Metallographic and chemical analyses performed on the plutonium rods showed that, after 10 passes, moderate movement of certain elements were achieved. Molten zone speeds of 1 or 2 inches per hour had no effect on impurity element movement. Likewise, the application of constant or variable power had no effect on impurity movement. The study implies that development of a zone refining process to purify plutonium is feasible. Development of a process will be hampered by two factors: (1) the effect on impurity element redistribution of the oxide layer formed on the exposed surface of the material is not understood, and (2) the tantalum container material is not inert in the presence of plutonium. Cold boat studies are planned, with higher temperature and vacuum levels, to determine the effect on these factors. 5 refs., 1 tab., 5 figs.
Date: May 1, 1997

Zone Refining of Plutonium Metal

Description: The zone refining process was applied to Pu metal containing known amounts of impurities. Rod specimens of plutonium metal were melted into and contained in tantalum boats, each of which was passed horizontally through a three-turn, high-frequency coil in such a manner as to cause a narrow molten zone to pass through the Pu metal rod 10 times. The impurity elements Co, Cr, Fe, Ni, Np, U were found to move in the same direction as the molten zone as predicted by binary phase diagrams. The elements Al, Am, and Ga moved in the opposite direction of the molten zone as predicted by binary phase diagrams. As the impurity alloy was zone refined, {delta}-phase plutonium metal crystals were produced. The first few zone refining passes were more effective than each later pass because an oxide layer formed on the rod surface. There was no clear evidence of better impurity movement at the slower zone refining speed. Also, constant or variable coil power appeared to have no effect on impurity movement during a single run (10 passes). This experiment was the first step to developing a zone refining process for plutonium metal.
Date: August 1, 1994
Creator: Blau, M. S.

Zone refining of sintered, microwave-derived YBCO superconductors

Description: Post-sintering treatments such as zone melting under thermal gradient has been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for {approx}4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 C for 5 h. The sintered tapes were subjected to repeated zone refining operations at relatively high speeds of {approx}30 mm/h. A microstructure having uniformly oriented grains in the a-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions, and microstructural features are presented in this paper.
Date: July 1, 1993
Creator: Warrier, K. G. K.; Varma, H. K.; Mani, T. V.; Damodaran, A. D. & Balachandran, U.

Zone sintering of ceramic fuels

Description: Cold pressed UC{sup 2} fuel compacts are sintered at temperatures greater than about 1850 C while in contract with a sintering facilitator material, e.g., tantalum, niobium, tungsten or a metal carbide such as uranium carbide, thereby allowing for a reduction in the overall porosity and leaving the desired product, i.e., a highly dense, large-grained uranium dicarbide. The process of using the sintering facilitator materials can be applied in the preparation of other carbide materials.
Date: December 31, 1991
Creator: Matthews, R.B.; Chidester, K.M. & Moore, H.G.

Zoning for Distributed Wind Power - Breaking Down Barriers: Preprint

Description: Zoning regulations for the use of small wind turbines vary from state to state and from one local jurisdiction to the next. This paper examines the zoning experiences of small wind turbine owners, options for local actions, and examples of state and federal limited preemption of local zoning authority as a means of promoting the implementation of new technologies.
Date: August 1, 2005
Creator: Green, J. & Sagrillo, M.

The ZOOM Fermilab physics class libraries

Description: Several years ago, the two major collider experiments at Fermilab (D#31; and CDF) decided that new software development for Run II will be largely done in C++. The run is slated to start in 1.5 years, an aggressive time frame for a major change in development language and style. If despite the transition each experiment (and sometimes multiple groups within an experiment) were to develop each needed mod- ule, the C++ strategy would not be advantageous. Thus it was deemed useful to have a library development group speci#12;cally responsive to Run II needs. This Fer- milab Physics Class Library Task Force (ZOOM) would also expand the core of C++ expertise available for Fermilab physicists to draw upon. C++ di#11;ers from Fortran in that the for common use of routines and libraries is greater. But this potential is not realized automatically. Unless coordina- tion issues are considered from the start, utilities produced by one group generally do mot meet the needs of other groups|and each group ends up creating independant software. To help increase code sharing, the centralized ZOOM task force must: Actively pursue outside (commercial and free-ware) packages. If ZOOM can verify that package X meets some needs in a sensible manner, then people can gravitate to that and not expend valuable development time. Act as a core for joint develpment of packages needed by both experiments. Develop relevant packages of su#14;ciently high quality as to overcome the natu- ral reluctance of highly skilled physicists to rely on code developed by others. This means more extensive design thought and testing work than might be practical for some groups. Participate in cooperation with HEP groups outside the FNAL community, to acquire tools suitable for the Fermilab e#11;orts. Of particular concern are areas where standardization is important, and thus a single product ...
Date: November 1, 1998
Creator: Mark Fischler, Walter Brown, Philippe Canal and John Marraffino

The ZOOM minimization package

Description: A new object-oriented Minimization package is available for distribution in the same manner as CLHEP. This package, designed for use in HEP applications, has all the capabilities of Minuit, but is a re-write from scratch, adhering to modern C++ design principles. A primary goal of this package is extensibility in several directions, so that its capabilities can be kept fresh with as little maintenance effort as possible. This package is distinguished by the priority that was assigned to C++ design issues, and the focus on producing an extensible system that will resist becoming obsolete.
Date: November 1, 2004
Creator: Fischler, Mark S. & Sachs, D.

A zoomable and adaptable hidden fine-mesh approach to solving advection-dispersion equations

Description: A zoomable and adaptable hidden fine-mesh approach (ZAHFMA), that can be used with either finite element or finite difference methods, is proposed to solve the advection-dispersion equation. The approach is based on automatic adaptation of zooming a hidden fine-mesh in the place where the sharp front locates. Preliminary results indicate that ZAHFMA used with finite element methods can handle the advection-dispersion problems with Peclet number ranging from 0 to infinity. 5 refs., 2 figs.
Date: January 1, 1988
Creator: Yeh, G.T.

A zooming Web browser

Description: We are developing a prototype zooming World-Wide Web browser within Pad++, a multiscale graphical environment. Instead of having a single page visible at a time, multiple pages and the links between them are depicted on a large zoomable information surface. Pages are scaled so that the page in focus is clearly readable with connected pages shown at smaller scales to provide context. We quantitatively compared performance with the Pad++ Web browser and Netscape in several different scenarios. We examined how quickly users could answer questions about a specific Web site designed for this test. Initially we found that subjects answered questions slightly slower with Pad++ than with Netscape. After analyzing the results of this study, we implemented several changes to the Pad++ Web browser, and repeated one Pad++ condition. After improvements were made to the Pad++ browser, subjects using Pad++ answered questions 23% faster than those using Netscape.
Date: December 31, 1996
Creator: Bederson, B.B.; Hollan, J.D.; Stewart, J.; Rogers, D.; Vick, D.; Ring, L. et al.

Zooplankton data: Vertical distributions of zooplankton in the Norweigian and Greenland Seas during summer, 1989

Description: Recent studies of zooplankton populations in the Greenland Sea have focused on processes at the Marginal Ice Zone (MIZ) and the areas immediately adjacent to it under the ice and in open water. These studies have shown a relatively short period of intense secondary productivity which is closely linked temporally and spatially to phytoplankton blooms occurring near the ice edge in spring and early summer. During the summer of 1989 we participated in a project focusing on benthic and water column processes in the basins of the Norwegian and Greenland Seas. This study allowed us to compare biological processes at the MIZ with those occurring in the open waters of the Greenland Sea, and to compare processes at both of these locations with those in the Norwegian Sea. The data presented in this report are the results of zooplankton net tows covering the upper 1000 meters of the water column over the Norwegian Sea basin and the Greenland Sea basin, and the upper 500 meters of open water adjacent to the MIZ in the Greenland Sea. Sampling was conducted between 12 and 29 July 1989.
Date: August 1, 1993
Creator: Lane, P. V. Z.; Smith, S. L. & Schwarting, E. M.

Zooplankton from OTEC sites in the Gulf of Mexico and the Caribbean

Description: The spatial and temporal variations in the abundance of major classes of zooplankton were measured using standard methods, between June and October 1978, at two OTEC sites in the Gulf of Mexico and in the Caribbean near Puerto Rico. The usual oceanic patterns were found with highest numbers near the surface, especially at night, and lowest numbers at 800 to 1000 m. Absolute numbers varied considerably from site to site. As expected, copepods (usually divided between calanoids and cyclopoids) dominated the zooplankton at all sites.
Date: June 1, 1979
Creator: Commins, M.L. & Horne, A.J.

ZORCH--AN IBM 7090 PROGRAM FOR THE ANALYSIS OF SIMULATED MSRE POWER TRANSIENTS WITH A SIMPLIFIED SPACE-DEPENDENT KINETICS MODEL

Description: A program (ZORCH) is described which is an extended and revised version of the point-model kinetics program MURGATROYD. A model is used in which the axial space dependence of the fuel and graphite temperatures is calculated, and the effect on reactivity of deviations from the steady state values is assumed to be given by the product of an appropriate temperature coefficient of reactivity times the deviations from the steady state value of the nuclear average temperature (NAT). The NAT is computed using a sine-squared'' weighting function in the axial direction and using an input weighting factor in the radial direction. The shape of the power density is taken to be - time- independent in contrast to the shapes of the temperature distributions, which are time-dependent in the calculation. This program is intended to be used in surveys of reactor behavior under a wide range of conditions. It is therefore based on a simplified model in order to reduce computing time, but should provide a better approximation to reactor behavior than does a purely space-independent calculation. A derivation of the equations used in the program, instructions for its use, and sample input and output for a test case are included. A FORTRAN source deck and a binary object deck are on file. (auth)
Date: September 18, 1962
Creator: Nestor, C.W. Jr.

ZORNOC: a 1 1/2-D tokamak data analysis code for studying noncircular high beta plasmas

Description: A new tokamak data analysis code, ZORNOC, was developed to study noncircular, high beta plasmas in the Impurity Study Experiment (ISX-B). These plasmas exhibit significant flux surface shifts and elongation in both ohmically heated and beam-heated discharges. The MHD equilibrium flux surface geometry is determined by solving the Grad-Shafranov equation based on: (1) the shape of the outermost flux surface, deduced from the magnetic loop probes; (2) a pressure profile, deduced by means of Thomson scattering data (electrons), charge exchange data (ions), and a Fokker-Planck model (fast ions); and (3) a safety factor profile, determined from the experimental data using a simple model (Z/sub eff/ = const) that is self-consistently altered while the plasma equilibrium is iterated. For beam-heated discharches the beam deposition profile is determined by means of a Monte Carlo scheme and the slowing down of the fast ions by means of an analytical solution of the Fokker-Planck equation. The code also carries out an electron power balance and calculates various confinement parameters. The code is described and examples of its operation are given.
Date: March 1, 1980
Creator: Zurro, B.; Wieland, R.M.; Murakami, M. & Swain, D.W.

ZPPR-20 phase D : a cylindrical assembly of polyethylene moderated U metal reflected by beryllium oxide and polyethylene.

Description: The Zero Power Physics Reactor (ZPPR) fast critical facility was built at the Argonne National Laboratory-West (ANL-W) site in Idaho in 1969 to obtain neutron physics information necessary for the design of fast breeder reactors. The ZPPR-20D Benchmark Assembly was part of a series of cores built in Assembly 20 (References 1 through 3) of the ZPPR facility to provide data for developing a nuclear power source for space applications (SP-100). The assemblies were beryllium oxide reflected and had core fuel compositions containing enriched uranium fuel, niobium and rhenium. ZPPR-20 Phase C (HEU-MET-FAST-075) was built as the reference flight configuration. Two other configurations, Phases D and E, simulated accident scenarios. Phase D modeled the water immersion scenario during a launch accident, and Phase E (SUB-HEU-MET-FAST-001) modeled the earth burial scenario during a launch accident. Two configurations were recorded for the simulated water immersion accident scenario (Phase D); the critical configuration, documented here, and the subcritical configuration (SUB-HEU-MET-MIXED-001). Experiments in Assembly 20 Phases 20A through 20F were performed in 1988. The reference water immersion configuration for the ZPPR-20D assembly was obtained as reactor loading 129 on October 7, 1988 with a fissile mass of 167.477 kg and a reactivity of -4.626 {+-} 0.044{cents} (k {approx} 0.9997). The SP-100 core was to be constructed of highly enriched uranium nitride, niobium, rhenium and depleted lithium. The core design called for two enrichment zones with niobium-1% zirconium alloy fuel cladding and core structure. Rhenium was to be used as a fuel pin liner to provide shut down in the event of water immersion and flooding. The core coolant was to be depleted lithium metal ({sup 7}Li). The core was to be surrounded radially with a niobium reactor vessel and bypass which would carry the lithium coolant to the forward inlet plenum. Immediately inside the ...
Date: September 30, 2006
Creator: Lell, R.; Grimm, K.; McKnight, R.; Shaefer, R.; Division, Nuclear Engineering & INL

ZPPR progress report: August 1987-October 1987

Description: This progress report details activities during the time period of August through October, 1987. Results are presented from the axially heterogeneous assembly ZPPR-17, a part of the Jupiter-III program. The loading of the ZPPR-17B assembly, with 25 control rod positions, is described along with operational measurements, calculation models, measurements and predictions of criticality and measured axial worth profiles for B[sub 4]C. From ZPPR-17A, calculated and measured results are given for banks of control rod positions along with revised measured values for various single, central control rods.
Date: November 16, 1987
Creator: Brumbach, S.B. & Collins, P.J.

ZPPR progress report: February 1988 through April 1988

Description: Results are presented for control rod worth experiments in the axially heterogeneous assembly ZPPR-17, a part of the JUPITER-III program. From the earlier metal-fuel ZPPR-15 program, results are given for measurements and calculations of neutron spectra and sodium voiding in several configurations.
Date: May 13, 1988
Creator: Brumbach, S.B. & Collins, P.J.

ZPPR progress report, January 1989 through April 1989

Description: Further results are presented from the large, homogeneous assembly ZPPR-18 in the JUPITER-III program. Reaction rate results are given for ZPPR-18B along with measured gamma ray dose results from ZPPR-18A and 18B. Control rod worth results from the ZPPR-18 assemblies are included. Calculation models, measured and calculated k-effective values and measured sodium worth values, are presented for the ZPPR-19 assemblies of the lo program.
Date: April 27, 1989
Creator: Collins, P.J. & Brumbach, S.B.

ZPPR progress report: November 1987-January 1988

Description: This report details activities for the time period of November, 1987 through January, 1988. Further results are presented from the axially heterogeneous assembly ZPPR-17, a part of the JUPITER-III program. The loading of the ZPPR-17C assembly, with 13 half-inserted control rods, is described along with operational measurements, calculation models, and measurements and prediction of criticality. From ZPPR-17A, calculated and measured results are given for reaction rates and measured results for bowing, expansion and small sample worth experiments. From the earlier metal-fuel ZPPR-15 program results are given for measurements and calculations of Doppler reactivity coefficients.
Date: February 15, 1988
Creator: Collins, P.J. & Brumbach, S.B.