Ceramic Processing (open access)

Ceramic Processing

Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referred to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or …
Date: November 24, 1999
Creator: EWSUK,KEVIN G.
Object Type: Article
System: The UNT Digital Library
Corrosion Issues in Solder Joint Design and Service (open access)

Corrosion Issues in Solder Joint Design and Service

Corrosion is an important consideration in the design of a solder joint. It must be addressed with respect to the service environment or, as in the case of soldered conduit, as the nature of the medium being transported within piping or tubing. Galvanic-assisted corrosion is of particular concern, given the fact that solder joints are comprised of different metals or alloy compositions that are in contact with one-another. The (thermodynamic) potential for corrosion to take place in a particular environment requires the availability of the galvanic series for those conditions and which includes the metals or alloys in question. However, the corrosion kinetics, which actually determine the rate of material loss under the specified service conditions, are only available through laboratory evaluations or field data that are found in the existing literature or must be obtained by in-house testing.
Date: November 24, 1999
Creator: VIANCO,PAUL T.
Object Type: Article
System: The UNT Digital Library
Current-limited imposed-potential technique for inducing and monitoring metastable pitting events (open access)

Current-limited imposed-potential technique for inducing and monitoring metastable pitting events

A technique has been developed to selectively induce metastable pitting while preventing the transition to stable pit growth. The current-limited imposed-potential (CLIP) technique limits available cathodic current to an initiated site using a resistor in series with the working electrode to form a voltage divider. Potentiodynamic CLIP testing yields a distribution of breakdown potentials from a single experiment. Potentiostatic CLIP testing yields induction time data, which can be used as input to a calculation of germination rate. Initial data indicate that a one-to-one correlation exists between electrochemical transients and observed pitting sites. The CLIP technique provides a consistent means of gathering quantitative potential and current transients associated with localized oxide breakdown.
Date: November 24, 1999
Creator: Wall, F.D.
Object Type: Article
System: The UNT Digital Library
A Database of Herbaceous Vegetation Responses to Elevated Atmospheric CO{sub 2} (open access)

A Database of Herbaceous Vegetation Responses to Elevated Atmospheric CO{sub 2}

To perform a statistically rigorous meta-analysis of research results on the response by herbaceous vegetation to increased atmospheric CO{sub 2} levels, a multiparameter database of responses was compiled from the published literature. Seventy-eight independent CO{sub 2}-enrichment studies, covering 53 species and 26 response parameters, reported mean response, sample size, and variance of the response (either as standard deviation or standard error). An additional 43 studies, covering 25 species and 6 response parameters, did not report variances. This numeric data package accompanies the Carbon Dioxide Information Analysis Center's (CDIAC's) NDP-072, which provides similar information for woody vegetation. This numeric data package contains a 30-field data set of CO{sub 2}-exposure experiment responses by herbaceous plants (as both a flat ASCII file and a spreadsheet file), files listing the references to the CO{sub 2}-exposure experiments and specific comments relevant to the data in the data sets, and this documentation file (which includes SAS{reg_sign} and Fortran codes to read the ASCII data file). The data files and this documentation are available without charge on a variety of media and via the Internet from CDIAC.
Date: November 24, 1999
Creator: Jones, M.H.
Object Type: Report
System: The UNT Digital Library
Design and development of a cathode processor for electrometallurgical treatment of spent nuclear fuel (open access)

Design and development of a cathode processor for electrometallurgical treatment of spent nuclear fuel

The electrometallurgical processing of spent fuel developed at Argonne National Laboratory produces a cathode which contains dendrites of heavy metal (principally U), salts, and residual cadmium. The cathode requires further treatment which is accomplished by loading it into a cathode processor to first purify and then consolidate the heavy metal. The principal steps in cathode processing are: the cathode is loaded into a crucible and both loaded into the cathode processor; the crucible is heated under vacuum to an intermediate temperature to distill the salt and cadmium from the crucible; the crucible is heated further to melt and consolidate the heavy metal; the crucible and charge are then cooled forming a heavy metal ingot in the crucible mold. The cathode processor development program has progressed through the design, fabrication, qualification, and demonstration phases. Two identical units were built. One (a prototype unit) has been installed at Argonne's site in Illinois and the other (the production unit) has been installed in the Fuel Conditioning Facility (FCF) at Argonne's Idaho site. Both units are presently in operation. The most recent activities completed in the FCF fuel processing project were the EBR-II driver fuel and blanket fuel demonstration phases. All of the cathode …
Date: November 24, 1999
Creator: Brunsvold, A. R.; Roach, P. D. & Westphal, B. R.
Object Type: Article
System: The UNT Digital Library
Food Assistance: Efforts to Control Fraud and Abuse in the Child and Adult Care Food Program Should be Strengthened (open access)

Food Assistance: Efforts to Control Fraud and Abuse in the Child and Adult Care Food Program Should be Strengthened

A letter report issued by the General Accounting Office with an abstract that begins "GAO reviewed the Food and Nutrition Service's (FNS) efforts to control the fraud and abuses occurring in its state administered Child and Adult Care Food Program, focusing on: (1) the extent to which the states have implemented required and recommended controls to prevent and detect fraud and abuse; and (2) FNS' effectiveness in directing the states' efforts to implement these controls."
Date: November 24, 1999
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Generalized b-spline subdivision-surface wavelets and lossless compression (open access)

Generalized b-spline subdivision-surface wavelets and lossless compression

We present a new construction of wavelets on arbitrary two-manifold topology for geometry compression. The constructed wavelets generalize symmetric tensor product wavelets with associated B-spline scaling functions to irregular polygonal base mesh domains. The wavelets and scaling functions are tensor products almost everywhere, except in the neighborhoods of some extraordinary points (points of valence unequal four) in the base mesh that defines the topology. The compression of arbitrary polygonal meshes representing isosurfaces of scalar-valued trivariate functions is a primary application. The main contribution of this paper is the generalization of lifted symmetric tensor product B-spline wavelets to two-manifold geometries. Surfaces composed of B-spline patches can easily be converted to this scheme. We present a lossless compression method for geometries with or without associated functions like color, texture, or normals. The new wavelet transform is highly efficient and can represent surfaces at any level of resolution with high degrees of continuity, except at a finite number of extraordinary points in the base mesh. In the neighborhoods of these points detail can be added to the surface to approximate any degree of continuity.
Date: November 24, 1999
Creator: Bertram, M; Duchaineau, M A; Hamann, B & Joy, K I
Object Type: Article
System: The UNT Digital Library
Housekeeping Closure Report for Corrective Action Unit 463: Areas 2, 3, 9, and 25 Housekeeping Waste Sites, Nevada Test Site, Nevada (open access)

Housekeeping Closure Report for Corrective Action Unit 463: Areas 2, 3, 9, and 25 Housekeeping Waste Sites, Nevada Test Site, Nevada

The Federal Facility Agreement and Consent Order was entered into by the State of Nevada, U.S. Department of Energy, and U.S. Department of Defense to identify sites of potential historical contamination and implement corrective actions based on public health and environmental considerations. The facilities subject to this agreement include the Nevada Test Site (NTS), parts of the Tonopah Test Range, parts of the Nellis Air Force Range, the Central Nevada Test Area, and the Project Shoal Area. Corrective Action Sites (CASs) are areas potentially requiring corrective actions and may include solid waste management units, individual disposal, or release sites. Based on geography, technical similarity, agency responsibility, or other appropriate reasons, CASs are grouped together into Corrective Action Units (CAUs) for the purposes of determining corrective actions. This report contains the Closure Verification Forms for cleanup activities that were performed at 13 CASs within CAU 463 on the NTS. The Housekeeping Closure Verification Form for each CAS provides the location, directions to the site, general description, and photographs of the site before and after cleanup activities. Housekeeping activities at these sites included removal of debris (e.g., wooden pallets, metal, glass, and trash) and other material. In addition, these forms confirm prior …
Date: November 24, 1999
Creator: United States. Department of Energy. Nevada Operations Office.
Object Type: Report
System: The UNT Digital Library
Implementation of a distributed multiterabyte storage system (open access)

Implementation of a distributed multiterabyte storage system

The University of Chicago and Argonne National Laboratory are building a highly distributed storage system to meet the needs of a cross-disciplinary group of scientists and to investigate the issues involved in implementing such a system. The storage system is based on IBM 3590/3494 tape technology managed by ADSM software. High-speed wide-area networking is required to support the distributed user community. NFS, DFS, FTP, and other user access methods are supported. A simulation project undertaken to guide system development has provided useful insights even in the calibration and design phases.
Date: November 24, 1999
Creator: Hereld, M.; Nickless, B. & Stevens, R.
Object Type: Report
System: The UNT Digital Library
Long-Range Neutron Detection (open access)

Long-Range Neutron Detection

A neutron detector designed for detecting neutron sources at distances of 50 to 100 m has been constructed and tested. This detector has a large surface area (1 m^2) to enhance detection efficiency, and it contains a collimator and shielding to achieve direction sensitivity and reduce background. An unusual feature of the detector is that it contains no added moderator, such as polyethylene, to moderate fast neutrons before they reach the 3He detector. As a result, the detector is sensitive mainly to thermal neutrons. The moderator-free design reduces the weight of the detector, making it more portable, and it also aids in achieving directional sensitivity and background reduction. Test results show that moderated fission-neutron sources of strength about 3 * 10^5 n/s can be detected at a distance out to 70 m in a counting time of 1000 s. The best angular resolution of the detector is obtained at distances of 30 m or less. As the separation distance between the source and detector increases, the contribution of scattered neutrons to the measured signal increases with a resultant decrease in the ability to detect the direction to a distant source. Applications for which the long-range detector appears to be suitable …
Date: November 24, 1999
Creator: Peurrung, Anthony J.; Stromswold, David C.; Hansen, Randy R.; Reeder, Paul L. & Barnett, Debra S.
Object Type: Report
System: The UNT Digital Library
Long-Range Neutron Detection (open access)

Long-Range Neutron Detection

A neutron detector designed for detecting neutron sources at distances of 50 to 100 m has been constructed and tested. This detector has a large surface area (1 m{sup 2}) to enhance detection efficiency, and it contains a collimator and shielding to achieve direction sensitivity and reduce background. An unusual feature of the detector is that it contains no added moderator, such as polyethylene, to moderate fast neutrons before they reach the {sup 3}He detector. As a result, the detector is sensitive mainly to thermal neutrons. The moderator-free design reduces the weight of the detector, making it more portable, and it also aids in achieving directional sensitivity and background reduction. Test results show that moderated fission-neutron sources of strength about 3 x 10{sup 5} n/s can be detected at a distance out to 70 m in a counting time of 1000 s. The best angular resolution of the detector is obtained at distances of 30 m or less. As the separation .distance between the source and detector increases, the contribution of scattered neutrons to the measured signal increases with a resultant decrease in the ability to detect the direction to a distant source. Applications for which the long-range detector appears …
Date: November 24, 1999
Creator: Peurrung, AJ; Stromswold, DC; Hansen, RR; Reeder, PL & Barnett, DS
Object Type: Report
System: The UNT Digital Library
Magnetic field generation from Self-Consistent collective neutrino-plasma interactions (open access)

Magnetic field generation from Self-Consistent collective neutrino-plasma interactions

A new Lagrangian formalism for self-consistent collective neutrino-plasma interactions is presented in which each neutrino species is described as a classical ideal fluid. The neutrino-plasma fluid equations are derived from a covariant relativistic variational principle in which finite-temperature effects are retained. This new formalism is then used to investigate the generation of magnetic fields and the production of magnetic helicity as a result of collective neutrino-plasma interactions.
Date: November 24, 1999
Creator: Brizard, A. J.; Murayama, H. & Wurtele, J. S.
Object Type: Article
System: The UNT Digital Library
Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy (open access)

Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy

We present a method for assessing the relative vulnerabilities of distinct classes of grain boundaries to localized corrosion. Orientation imaging microscopy provides a spatial map which identifies and classifies grain boundaries at a metal surface. Once the microstructure of a region of a sample surface has been characterized, a sample can be exposed to repeated cycles of exposure to a corrosive environment alternating with topographic measurement by an atomic force microscope in the same region in which the microstructure had been mapped. When this procedure is applied to Ni and Ni-based alloys, we observe enhanced attack at random grain boundaries relative to special boundaries and twins in a variety of environments.
Date: November 24, 1999
Creator: Bedrossian, P. J.
Object Type: Article
System: The UNT Digital Library
Review of Subcritical Source-Driven Noise Analysis Measurements (open access)

Review of Subcritical Source-Driven Noise Analysis Measurements

Subcritical source-driven noise measurements are simultaneous Rossi-{alpha} and randomly pulsed neutron measurements that provide measured quantities that can be related to the subcritical neutron multiplication factor. In fact, subcritical source-driven noise measurements should be performed in lieu of Rossi-{alpha} measurements because of the additional information that is obtained from noise measurements such as the spectral ratio and the coherence functions. The basic understanding of source-driven noise analysis measurements can be developed from a point reactor kinetics model to demonstrate how the measured quantities relate to the subcritical neutron multiplication factor. More elaborate models can also be developed using a generalized stochastic model. These measurements can be simulated using Monte Carlo codes to determine the subcritical neutron multiplication factor or to determine the sensitivity of calculations to nuclear cross section data. The interpretation of the measurement using a Monte Carlo method is based on a perturbation model for the relationship between the spectral ratio and the subcritical neutron multiplication factor. The subcritical source-driven noise measurement has advantages over other subcritical measurement methods in that reference measurements at delayed critical are not required for interpreting the measurements. Therefore, benchmark or in-situ subcritical measurements can be performed outside a critical experiment facility. Furthermore, …
Date: November 24, 1999
Creator: Valentine, T.E.
Object Type: Report
System: The UNT Digital Library
Solid State Experiments at High Pressure and Strain Rates (open access)

Solid State Experiments at High Pressure and Strain Rates

Experiments have been developed using high powered laser facilities to study the response of materials in the solid state under extreme pressures and strain rates. Details of the target and drive development required for solid state experiments and results from two separate experiments are presented. In the first, thin foils were compressed to a peak pressure of 180 GPa and accelerated. A pre-imposed modulation at the embedded RT unstable interface was observed to grow. The growth rates were fluid-like at early time, but suppressed at later time. This result is suggestive of the theory of localized heating in shear bands, followed by dissipation of the heat, allowing for recovery of the bulk material strength. In the second experiment, the response of Si was studied by dynamic x-ray diffraction. The crystal was observed to respond with uni-axial compression at a peak pressure 11.5-13.5 GPa.
Date: November 24, 1999
Creator: Kalantar, D. H.; Remington, B. A.; Colvin, J. D.; Mikaelian, K. O.; Weber, S. V.; Wiley, L. G. et al.
Object Type: Article
System: The UNT Digital Library
Using Cytochrome c{sub 3} to Make Selenium Nanowires (open access)

Using Cytochrome c{sub 3} to Make Selenium Nanowires

We report on a new method to make nanostructures, in this case selenium nanowires, in aqueous solution at room temperature. We used the protein cytochrome c{sub 3} to reduce selenate (SeO{sub 4}{sup 2{minus}}) to selenium (Se{sup 0}). Cytochrome c{sub 3} is known for its ability to catalyze reduction of metals including U{sup VI} {yields} U{sup IV}, Cr{sup VI} {yields} Cr{sup III}, Mo{sup VI} {yields} Mo{sup IV}, Cu{sup II} {yields} Cu{sup 0}, Pb{sup II} {yields} Pb{sup 0}, Hg{sup II} {yields} Hg{sup 0}. Nanoparticles of Se{sup 0} precipitated from an aqueous solution at room temperature, followed by spontaneous self-assembling into nanowires. Cytochrome c{sub 3} was extracted from the sulfate-reducing bacteria Desulfovibrio vulgaris (strain Holdenborough) and isolated by the procedure of DerVartanian and Legall.
Date: November 24, 1999
Creator: Abdelouas, A.; Franco, R.; Gong, W. L.; Lutze, W.; Moura, I. & Shelnutt, John A.
Object Type: Article
System: The UNT Digital Library
324 Facility B-cell quality process plan (open access)

324 Facility B-cell quality process plan

Quality Process Plan for the Restart of Cell Hot-Work. Addition of Table 5B.
Date: November 24, 1998
Creator: RIDDELLE, J.G.
Object Type: Report
System: The UNT Digital Library
324 Facility B-cell quality process plan (open access)

324 Facility B-cell quality process plan

Quality Process Plan for the Restart of Cell Hot-Work. Addition of Table 6a.
Date: November 24, 1998
Creator: RIDDELLE, J.G.
Object Type: Report
System: The UNT Digital Library
Advanced Diagnostics for Developing High-Brightness Electron Beams (open access)

Advanced Diagnostics for Developing High-Brightness Electron Beams

The production of high-brightness particle beams calls for the development of advanced beam diagnostics. High brightness beams, meaning beams with a high density in phase space, are important for many applications, such as short-wavelength Free-Electron Lasers and advanced accelerator systems. A diagnostic that provides detailed information on the density distribution of the electron bunch in multi-dimensional phase-space is an essential tool for obtaining small emittance at a high charge. This diagnostic system has been developed at Brookhaven National Laboratory. One component of the system is the measurement of a slice emittance which provides a measurement of transverse beam properties (such as emittance) as a function of the longitudinal position. Changing the laser pulse profile of a photocathode RF gun has been suggested as one way to achieve non-linear emittance compensation and improve the brightness and that can be diagnosed by the slice emittance system. The other element of the diagnostic is the tomographic reconstruction of the transverse phase. In our work we give special attention to the accuracy of the phase space reconstruction and present an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases. This high precision phase space tomography …
Date: November 24, 1998
Creator: Ben-Zvi, Ilan; Babzien, M.; Malone, R.; Wang, X. J. & Yakimenko, V.
Object Type: Article
System: The UNT Digital Library
Advanced Diagnostics for Developing High-Brightness Electron Beams. (open access)

Advanced Diagnostics for Developing High-Brightness Electron Beams.

The production of high-brightness particle beams calls for the development of advanced beam diagnostics. High brightness beams, meaning beams with a high density in phase space, are important for many applications, such as short-wavelength Free-Electron Lasers and advanced accelerator systems. A diagnostic that provides detailed information on the density distribution of the electron bunch in multi-dimensional phase-space is an essential tool for obtaining small emittance at a high charge. This diagnostic system has been developed at Brookhaven National Laboratory. One component of the system is the measurement of a slice emittance which provides a measurement of transverse beam properties (such as emittance) as a function of the longitudinal position. Changing the laser pulse profile of a photocathode RF gun has been suggested as one way to achieve non-linear emittance compensation and improve the brightness and that can be diagnosed by the slice emittance system. The other element of the diagnostic is the tomographic reconstruction of the transverse phase. In our work we give special attention to the accuracy of the phase space reconstruction and present an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases. This high precision phase space tomography …
Date: November 24, 1998
Creator: Ben-Zvi, Ilan
Object Type: Article
System: The UNT Digital Library
Chemical Kinetics for Modeling Silicon Epitaxy from Chlorosilanes (open access)

Chemical Kinetics for Modeling Silicon Epitaxy from Chlorosilanes

A reaction mechanism has been developed that describes the gas-phas 0971 and surface reactions involved in the chemical vapor deposition of Si from chlorosilanes. Good agreement with deposition rate data from a single wafer reactor with no wafer rotation has been attained over a range of gas mixtures, total flow rates, and reactor temperatures.
Date: November 24, 1998
Creator: Balakrishna, A.; Chacin, J.M.; Comita, P.B.; Haas, B.; Ho, P. & Thilderkvist, A.
Object Type: Article
System: The UNT Digital Library
Clean Water Act Issues in the 106th Congress (open access)

Clean Water Act Issues in the 106th Congress

In the 106th Congress, no comprehensive activity on reauthorizing the Clean Water Act occurred, although a number of individual clean water bills were enacted. Other issues have been debated recently, such as reforming the law to provide regulatory relief for industry, states and cities, and individual landowners. The debate over many of these issues highlights differing views of the Act and its implementation by some who seek to strengthen existing requirements and others who believe that costs and benefits should be more carefully weighed before additional control programs are mandated.
Date: November 24, 1998
Creator: Copeland, Claudia
Object Type: Report
System: The UNT Digital Library
Electron heat transport in improved confinement discharges in DIII-D (open access)

Electron heat transport in improved confinement discharges in DIII-D

In DIII-D tokamak plasmas with an internal transport barrier (ITB), the comparison of gyrokinetic linear stability (GKS) predictions with experiments in both low and strong negative magnetic shear plasmas provide improved understanding for ion and electron thermal transport within much of the plasma. As previously reported, the region for improved ion transport seems well characterized by the condition OE~B>Y-, where SERB is the ExB flow shear, calculated from measured quantities, and y,, is the maximum linear growth rate for ion temperature gradient (ITG) modes in the absence of flow shear. Within a limited region just inside the ITB, the electron temperature gradient (ETG) modes appear to control the electron temperature gradient and, consequently, the electron thermal transport. The increase in electron temperature gradient with more strongly negative magnetic shear is consistent with the increase in the ETG mode marginal gradient. Closer to the magnetic axis the Te profile flattens and the ETG modes are predicted to be stable. With additional core electron heating, FIR scattering measurements near the axis show the presence of high k fluctuations (12 cm-l), rotating in the electron diamagnetic drift direction. This turbulence could impact electron transport and possibly also ion transport. Thermal diffusivities for electrons, …
Date: November 24, 1998
Creator: Stallard, B. W.
Object Type: Article
System: The UNT Digital Library
Environmental Effects in Advanced Intermetallics (open access)

Environmental Effects in Advanced Intermetallics

This paper provides a comprehensive review of environmental embrittlement in iron and nickel aluminizes. The embrittlement involves the interaction of these intermetallics with moisture in air and generation of atomic hydrogen, resulting in hydrogen-induced embrittlement at ambient temperatures. Environmental embrittlement promotes brittle grain-boundary fracture in Ni{sub 3}Al alloys but brittle cleavage fracture in Fe{sub 3}Al-FeAl alloys. The embrittlement strongly depends on strain rate, with tensile-ductility increase with increasing strain rate. It has been demonstrated that environmental embrittlement can be alleviated by alloying additions, surface modifications, and control of grain size and shape. Boron tends to segregate strongly to grain boundaries and is most effective in suppressing environmental embrittlement in Ni{sub 3}Al alloys. The mechanistic understanding of alloy effects and environmental embrittlement has led to the development of nickel and iron aluminide alloys with improved properties for structural use at elevated temperatures in hostile environments.
Date: November 24, 1998
Creator: Liu, C.T.
Object Type: Article
System: The UNT Digital Library