Decadal- to interannual-scale source water variations in the Caribbean Sea recorded by Puerto Rican coral radiocarbon (open access)

Decadal- to interannual-scale source water variations in the Caribbean Sea recorded by Puerto Rican coral radiocarbon

Water that forms the Florida Current, and eventually the Gulf Stream, coalesces in the Caribbean from both subtropical and equatorial sources. The equatorial sources are made up of, in part, South Atlantic water moving northward and compensating for southward flow at depth related to meridional overturning circulation. Subtropical surface water contains relatively high amounts of radiocarbon ({sup 14}C), whereas equatorial waters are influenced by the upwelling of low {sup 14}C water and have relatively low concentrations of {sup 14}C. We use a 250-year record of {Delta}{sup 14}C in a coral from southwestern Puerto Rico along with previously published coral {Delta}{sup 14}C records as tracers of subtropical and equatorial water mixing in the northern Caribbean. Data generated in this study and from other studies indicate that the influence of either of the two water masses can change considerably on interannual to interdecadal time scales. Variability due to ocean dynamics in this region is large relative to variability caused by atmospheric {sup 14}C changes, thus masking the Suess effect at this site. A mixing model produced using coral {Delta}{sup 14}C illustrates the time varying proportion of equatorial versus subtropical waters in the northern Caribbean between 1963 and 1983. The results of the …
Date: December 5, 2006
Creator: Kilbourne, K. H.; Quinn, T. M.; Guilderson, T. P.; Webb, R. S. & Taylor, F. W.
Object Type: Article
System: The UNT Digital Library
Developing Poultry Facility Type Information from USDA Agricultural Census Data for Use in Epidemiological and Economic Models (open access)

Developing Poultry Facility Type Information from USDA Agricultural Census Data for Use in Epidemiological and Economic Models

The epidemiological and economic modeling of poultry diseases requires knowing the size, location, and operational type of each poultry type operation within the US. At the present time, the only national database of poultry operations that is available to the general public is the USDA's 2002 Agricultural Census data, published by the National Agricultural Statistics Service, herein referred to as the 'NASS data'. The NASS data provides census data at the county level on poultry operations for various operation types (i.e., layers, broilers, turkeys, ducks, geese). However, the number of farms and sizes of farms for the various types are not independent since some facilities have more than one type of operation. Furthermore, some data on the number of birds represents the number sold, which does not represent the number of birds present at any given time. In addition, any data tabulated by NASS that could identify numbers of birds or other data reported by an individual respondent is suppressed by NASS and coded with a 'D'. To be useful for epidemiological and economic modeling, the NASS data must be converted into a unique set of facility types (farms having similar operational characteristics). The unique set must not double count …
Date: December 5, 2007
Creator: Melius, C
Object Type: Report
System: The UNT Digital Library
Development of High Waste Loading Glasses for Advanced Melter Technologies (open access)

Development of High Waste Loading Glasses for Advanced Melter Technologies

The vitrification programs at Hanford and Savannah River may benefit from higher temperature glass formulations that are processable in advanced melters (e.g., induction-heated, cold-crucible melter (ICCM)) or by changing the current liquidus temperature (TL) limit for Joule heated ceramic melters (JHCM). The focus of this report was on the glass formulation activities in support of the ICCM and JHCM demonstrations with C-106/AY-102 simulant. The intent was to provide preliminary (non-optimized) glass formulations for a specific waste stream that met processing requirements, DOE product quality specifications, and programmatic objectives for the two melter types.
Date: December 5, 2002
Creator: Peeler, D.K.
Object Type: Report
System: The UNT Digital Library
The diffractive structure function at the Tevatron: CDF results (open access)

The diffractive structure function at the Tevatron: CDF results

None
Date: December 5, 2000
Creator: Goulianos, K.
Object Type: Article
System: The UNT Digital Library
Diffusion Resistant, High-Purity Wafer Carriers For SI Semiconductor Production (open access)

Diffusion Resistant, High-Purity Wafer Carriers For SI Semiconductor Production

The Cooperative Research and Development Agreement (CRADA) was directed towards development of diffusion resistant, high-purity wafer carriers for Si semiconductor production with improved properties compared to current materials. The determination of the infiltration behavior is important for controlling the fabrication process to obtain consistent high-quality products. Ammonium molybdate or molybdenum carbide were found to be suitable as a precursor to produce SiC-MoSi{sub 2}-Si composites by Si infiltration into carbon preforms. Experiments on the pyrolysis of the preforms showed variable infiltration behavior by the molten Si (within the range of conditions in the present study). Further research is required to reproducibly and consistently fabricate flaw-free articles. The strength of the composites fabricated to-date was 325 {+-} 124 MPa, which is higher than current commercial products. Better process control should result in higher average strengths and reduce the variability.
Date: December 5, 2000
Creator: Tiegs, T. N.
Object Type: Report
System: The UNT Digital Library
Economical Recovery of By-products in the Mining Industry (open access)

Economical Recovery of By-products in the Mining Industry

The U.S. Department of Energy (DOE) Office of Industrial Technologies, Mining Industry of the Future Program, works with the mining industry to further the industry's advances toward environmental and economic goals. Two of these goals are (1) responsible emission and by-product management and (2) low-cost and efficient production (DOE 1998). DOE formed an alliance with the National Mining Association (NMA) to strengthen the basis for research projects conducted to benefit the mining industry. NMA and industry representatives actively participate in this alliance by evaluating project proposals and by recommending research project selection to DOE. Similarly, the National Research Council (NRC) has recently and independently recommended research and technology development opportunities in the mining industry (NRC 2001). The Oak Ridge National Laboratory (ORNL) and Colorado School of Mines engineers conducted one such project for DOE regarding by -product recovery from mining process residue. The results of this project include this report on mining industry process residue and waste with opportunity for by-product recovery. The U.S. mineral processing industry produces over 30,000,000 metric tons per year of process residue and waste that may contain hazardous species as well as valuable by-products. This study evaluates the copper, lead, and zinc commodity sectors which …
Date: December 5, 2001
Creator: Berry, J.B.
Object Type: Report
System: The UNT Digital Library
The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers (open access)

The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6{trademark} silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
Date: December 5, 2006
Creator: Marzik, J V; Croft, W J; Staples, R J & MoberlyChan, W J
Object Type: Article
System: The UNT Digital Library
Effect of small-scale fractures on flow and transport processes at Yucca Mountain, Nevada (open access)

Effect of small-scale fractures on flow and transport processes at Yucca Mountain, Nevada

Although many conceptual models for fracture-matrix interaction have been evaluated for Yucca Mountain site-characterization studies, the most widely used model is currently based on the dual-permeability concept. It was chosen for use in site-characterization partially because it has proved to be capable of matching many types of field observed data. Another consideration is that net infiltration rates at the site are estimated to be very low (on the order of millimeters/year), or close to saturated matrix hydraulic conductivity. Recent field studies and tests, in particular, fracture mapping data, collected along the walls of the underground tunnels reveal that there exists a significantly large variety in fracture sizes from centimeters to tens of meters. There is a considerable amount of small-scale fractures that have not been considered in the previous modeling studies. Although the majority of these small fractures may not contribute much to global flow and transport through the fracture-matrix system, they may provide large amounts of storage pore space and allow for additional connection areas for well-connected, large-scale fractures and surrounding matrix blocks, which ultimately affect fracture-matrix interactions. However, the currently used dual-permeability model is unable to include the potentially important effect of small fractures. To overcome the limitations …
Date: December 5, 2002
Creator: Wu, Yu-Shu; Liu, H.H. & Bodvarsson, G.S.
Object Type: Article
System: The UNT Digital Library
Evaluation of the Reproductive Success of Wild and Hatchery Steelhead in Hatchery and Natural and Hatchery Environments : Annual Report for 2008. (open access)

Evaluation of the Reproductive Success of Wild and Hatchery Steelhead in Hatchery and Natural and Hatchery Environments : Annual Report for 2008.

This report summarizes the field, laboratory, and analytical work from December 2007 through November 2008 on a research project that investigates interactions and comparative reproductive success of wild and hatchery origin steelhead (Oncorhynchus mykiss) trout in Forks Creek, a tributary of the Willapa River in southwest Washington. First, we continued to successfully sample hatchery and wild (i.e., naturally spawned) adult and wild smolt steelhead at Forks Creek. Second, we revealed microsatellite genotype data for adults and smolts through brood year 2008. Finally, four formal scientific manuscripts were published in 2008 and two are in press, one is in revision and two are in preparations.
Date: December 5, 2008
Creator: Quinn, Thomas P.; Seamons, todd; Hauser, Lorenz & Naish, Kerry
Object Type: Report
System: The UNT Digital Library
EVALUATION OF THERMAL CONDUCTIVITY OF INSTALLED-IN-PLACE POLYURETHANE FOAM INSULATION BY EXPERIMENT AND ANALYSIS (open access)

EVALUATION OF THERMAL CONDUCTIVITY OF INSTALLED-IN-PLACE POLYURETHANE FOAM INSULATION BY EXPERIMENT AND ANALYSIS

In the thermal analysis of the 9977 package, it was found that calculated temperatures, determined using a typical thermal analysis code, did not match those measured in the experimental apparatus. The analysis indicated that the thermal resistance of the overpack in the experimental apparatus was less than that expected, based on manufacturer's reported value of thermal conductivity. To resolve this question, the thermal conductivity of the installed foam was evaluated from the experimental results, using a simplified analysis. This study confirmed that the thermal resistance of the experimental apparatus was lower than that which would result from the manufacturer's published values for thermal conductivity of the foam insulation. The test package was sectioned to obtain samples for measurement of material properties. In the course of the destructive examination a large uninsulated region was found at the bottom of the package, which accounted for the anomalous results. Subsequent measurement of thermal conductivity confirmed the manufacturer's published values. The study provides useful insight into the use of simplified, scoping calculations for evaluation of thermal performance of packages.
Date: December 5, 2007
Creator: Smith, A; Bruce Hardy, B; Kurt Eberl, K & Nick Gupta, N
Object Type: Article
System: The UNT Digital Library
Exclusive Hadronic Final States in E+ E- Interactions at BaBar (open access)

Exclusive Hadronic Final States in E+ E- Interactions at BaBar

The first observation of e{sup +}e{sup -} annihilation into states of positive C parity, {rho}{sup 0}{rho}{sup 0} and {phi}{phi}{sup 0} is reported. It is shown that these final states are produced through two-virtual-photon annihilation. this is based on the distributions of cos{theta}*, where {theta}* is the center-of-mass polar angle of {phi} or {rho}{sup 0}. The cross sections for the |cos{theta}*| < 0.8 are measured. In addition, the observation of another channel, e{sup +}e{sup -} {yields} {phi}{eta} near {radical}s = 10.58 Gev with a significance of 6.5{sigma} is discussed. The cross section of the later channel for |cos{theta}*| < 0.8 is measured, where {theta}* is the center-of-mass polar angle of {phi} meson.
Date: December 5, 2007
Creator: Saremi, Sepehr
Object Type: Article
System: The UNT Digital Library
Fatigue of polycrystalline silicon for MEMS applications: Crack growth and stability under resonant loading conditions (open access)

Fatigue of polycrystalline silicon for MEMS applications: Crack growth and stability under resonant loading conditions

Although bulk silicon is not known to exhibit susceptibility to cyclic fatigue, micron-scale structures made from silicon films are known to be vulnerable to degradation by fatigue in ambient air environments, a phenomenon that has been recently modeled in terms of a mechanism of sequential oxidation and stress-corrosion cracking of the native oxide layer.
Date: December 5, 2001
Creator: Muhlstein, C. L.; Howe, R. T. & Ritchie, R. O.
Object Type: Article
System: The UNT Digital Library
Ferrenberg Swendsen Analysis of LLNL and NYBlue BG/L p4rhms Data (open access)

Ferrenberg Swendsen Analysis of LLNL and NYBlue BG/L p4rhms Data

These results are from the continuing Lattice Quantum Chromodynamics runs on BG/L. These results are from the Ferrenberg-Swendsen analysis [?] of the combined data from LLNL and NYBlue BG/L runs for 32{sup 3} x 8 runs with the p4rhmc v2.0 QMP-MPI.X (semi-optimized p4 code using qmp over mpi). The jobs include beta values ranging from 3.525 to 3.535 with an alternate analysis extending to 3.540. The NYBlue data sets are from 9k trajectories from Oct 2007, and the LLNL data are from two independent streams of {approx}5k each, taking from the July 2007 runs. The following outputs are produced by the fs-2+1-chiub.c program. All outputs have had checksums produced by addCks.pl and checked by the checkCks.pl perl script after scanning.
Date: December 5, 2007
Creator: Soltz, R.
Object Type: Report
System: The UNT Digital Library
Field Test of Advanced Duct-Sealing Technologies Within the Weatherization Assistance Program (open access)

Field Test of Advanced Duct-Sealing Technologies Within the Weatherization Assistance Program

A field test of an aerosol-spray duct-sealing technology and a conventional, best-practice approach was performed in 80 homes to determine the efficacy and programmatic needs of the duct-sealing technologies as applied in the U.S. Department of Energy Weatherization Assistance Program. The field test was performed in five states: Iowa, Virginia, Washington, West Virginia, and Wyoming. The study found that, compared with the best-practice approach, the aerosol-spray technology is 50% more effective at sealing duct leaks and can potentially reduce labor time and costs for duct sealing by 70%, or almost 4 crew-hours. Further study to encourage and promote use of the aerosol-spray technology within the Weatherization Assistance Program is recommended. A pilot test of full production weatherization programs using the aerosol-spray technology is recommended to develop approaches for integrating this technology with other energy conservation measures and minimizing impacts on weatherization agency logistics. In order to allow or improve adoption of the aerosol spray technology within the Weatherization Assistance Program, issues must be addressed concerning equipment costs, use of the technology under franchise arrangements with Aeroseal, Inc. (the holders of an exclusive license to use this technology), software used to control the equipment, safety, and training. Application testing of the …
Date: December 5, 2001
Creator: Ternes, MP
Object Type: Report
System: The UNT Digital Library
A Flexure-Based Tool Holder for Sub-(micro)m Positioning of a Single Point Cutting Tool on a Four-axis Lathe (open access)

A Flexure-Based Tool Holder for Sub-(micro)m Positioning of a Single Point Cutting Tool on a Four-axis Lathe

A tool holder was designed to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-{micro}m accuracy on a four-axis lathe. A four-axis lathe incorporates a rotary table that allows the cutting tool to swivel with respect to the workpiece to enable the machining of complex workpiece forms, and accurately machining complex meso-scale parts often requires that the cutting tool be aligned precisely along the axis of rotation of the rotary table. The tool holder designed in this study has greatly simplified the process of setting the tool in the correct location with sub-{micro}m precision. The tool holder adjusts the tool position using flexures that were designed using finite element analyses. Two flexures adjust the lateral position of the tool to align the center of the nose of the tool with the axis of rotation of the B-axis, and another flexure adjusts the height of the tool. The flexures are driven by manual micrometer adjusters, each of which provides a minimum increment of motion of 20 nm. This tool holder has simplified the process of setting a tool with sub-{micro}m accuracy, and it has significantly reduced the time required to set a tool.
Date: December 5, 2005
Creator: Bono, M J & Hibbard, R L
Object Type: Article
System: The UNT Digital Library
FRACTIONAL CRYSTALLIZATION OF HANFORD SINGLE SHELL TANK (SST) WASTES LABORATORY DEVELOPMENT (open access)

FRACTIONAL CRYSTALLIZATION OF HANFORD SINGLE SHELL TANK (SST) WASTES LABORATORY DEVELOPMENT

Laboratory studies demonstrate that fractional crystallization is a viable process for separating Hanford medium-curie waste into high-curie and low-curie fractions. The product salt from the crystallization process qualifies as low-curie feed to a supplemental treatment system (e.g., bulk vitrification). The high-curie raffinate is returned to the double-shell tank system, eventually to be sent as feed to the Waste Treatment and Immobilization Plant. Process flowsheet tests were designed with the aid of thermodynamic chemical modeling. Laboratory equipment design and test procedures were developed using simulated tank waste samples. Proof-of-concept flowsheet tests were carried out in a shielded hot cell using actual tank waste samples. Data from both simulated waste tests and actual tank waste tests demonstrate that the process exceeded all of the separation criteria established for the program.
Date: December 5, 2006
Creator: HERTING, D.L.
Object Type: Article
System: The UNT Digital Library
Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2006 (open access)

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2006

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and to report leachate results in fulfillment of the requirements specified in the ERDF ROD.
Date: December 5, 2007
Creator: Weiss, R. L.
Object Type: Report
System: The UNT Digital Library
Hyperspectral Imaging of Functional Patterns for Disease Assessment and Treatment Monitoring (open access)

Hyperspectral Imaging of Functional Patterns for Disease Assessment and Treatment Monitoring

We have designed and built a six-band multi-spectral NIR imaging system used in clinical testing on cancer patients. From our layered tissue model, we create blood volume and blood oxygenation images for patient treatment monitoring.
Date: December 5, 2003
Creator: Hassan, Moinuddin; Hattery, David; Vogel, Abby; Chernomorkik, Victor; Demos, Stavros; Aleman, Karen et al.
Object Type: Article
System: The UNT Digital Library
Ignition on the National Ignition Facility (open access)

Ignition on the National Ignition Facility

None
Date: December 5, 2007
Creator: Moses, Edward
Object Type: Article
System: The UNT Digital Library
Imaging with Mass Spectrometry: A SIMS and VUV-Photoionization Study of Ion-Sputtered Atoms and Clusters from GaAs and Au (open access)

Imaging with Mass Spectrometry: A SIMS and VUV-Photoionization Study of Ion-Sputtered Atoms and Clusters from GaAs and Au

A new mass spectrometry surface imaging method is presented in which ion-sputtered neutrals are postionized by wavelength-tunable vacuum ultraviolet (VUV) light from a synchrotron source. Mass spectra and signal counts of the photoionized neutrals from GaAs (100) and Au are compared to those of the secondary ions. While clusters larger than dimers are more efficiently detected as secondary ions, certain species, such as As2, Au and Au2, are more efficiently detected through the neutral channel. Continuously tuning the photon wavelength allows photoionization efficiency (PIE) curves to be obtained for sputtered Asm (m=1,2) and Aun (n=1-4). From the observed ionization thresholds, sputtered neutral As and Au show no clear evidence of electronic excitation, while neutral clusters have photoionization onsets shifted to lower energies by ~;;0.3 eV. These shifts are attributed to unresolved vibrational and rotational excitations. High-spatial resolution chemical imaging with synchrotron VUV postionization is demonstrated at two different photon energies using a copper TEM grid embedded in indium. The resulting images are used to illustrate the use of tunable VUV light for verifying mass peak assignments by exploiting the unique wavelength-dependent PIE of each sputtered neutral species. This capability is valuable for identifying compounds when imaging chemically complex systems with …
Date: December 5, 2008
Creator: Takahashi, Lynelle; Zhou, Jia; Wilson, Kevin R.; Leone, Stephen R. & Ahmed, Musahid
Object Type: Article
System: The UNT Digital Library
Impaired fertility in T-stock female mice after superovulation (open access)

Impaired fertility in T-stock female mice after superovulation

Superovulation of female mice with exogenous gonadotrophins is routinely used for increasing the number of eggs ovulated by each female in reproductive and developmental studies. We report an unusual effect of superovulation on fertilization in mice. In vivo matings of superovulated T-stock females with B6C3F1 males resulted in a 2-fold reduction (P<0.001) in the frequencies of fertilized eggs compared to control B6C3F1 matings. In addition, {approx}22 hr after mating only 15% of fertilized eggs recovered in T-stock females had reached the metaphase stage of the first cleavage division versus 87% in B6C3F1 females (P < 0.0001). Matings with T-stock males did not improve the reproductive performance of T-stock females. To investigate the possible cause(s) for the impaired fertilization and zygotic development, the experiments were repeated using in vitro fertilization. Under these conditions, the frequencies of fertilized eggs were not different in superovulated T-stock and B6C3F1 females (51.7% {+-} 6.0 and 64.5% {+-}3.8, P=0.10). There was a 7-fold increase in the frequencies of fertilized T-stock eggs that completed the first cell cycle of development after in vitro versus in vivo fertilization. These results rule out an intrinsic deficiency of the T-stock oocyte as the main reason for the impaired fertility after …
Date: December 5, 2003
Creator: Wyrobek, A J; Bishop, J B; Marchetti, F & Zudova, D
Object Type: Article
System: The UNT Digital Library
An Improved BGK-Type Collision-Term Model for Direct Simulation Monte Carlo (DSMC) Methods (open access)

An Improved BGK-Type Collision-Term Model for Direct Simulation Monte Carlo (DSMC) Methods

None
Date: December 5, 2000
Creator: GALLIS,MICHAIL A. & TORCZYNSKI,JOHN R.
Object Type: Article
System: The UNT Digital Library
Intelligent Signal Processing for Detection System Optimization (open access)

Intelligent Signal Processing for Detection System Optimization

A wavelet-neural network signal processing method has demonstrated approximately tenfold improvement over traditional signal-processing methods for the detection limit of various nitrogen and phosphorus compounds from the output of a thermionic detector attached to a gas chromatograph. A blind test was conducted to validate the lower detection limit. All fourteen of the compound spikes were detected when above the estimated threshold, including all three within a factor of two above the threshold. In addition, two of six spikes were detected at levels of 1/2 the concentration of the nominal threshold. Another two of the six would have been detected correctly if we had allowed human intervention to examine the processed data. One apparent false positive in five nulls was traced to a solvent impurity, whose presence was subsequently identified by analyzing a solvent aliquot evaporated to 1% residual volume, while the other four nulls were properly classified. We view this signal processing method as broadly applicable in analytical chemistry, and we advocate that advanced signal processing methods should be applied as directly as possible to the raw detector output so that less discriminating preprocessing and post-processing does not throw away valuable signal.
Date: December 5, 2004
Creator: Fu, C. Y.; Petrich, L. I.; Daley, P. F. & Burnham, A. K.
Object Type: Article
System: The UNT Digital Library
Interconnecting Single-Phase Generation to the Utility Distribution System (open access)

Interconnecting Single-Phase Generation to the Utility Distribution System

One potentially large source of underutilized distributed generation (DG) capacity exists in single-phase standby backup gensets on farms served from single-phase feeder laterals. Utilizing the excess capacity would require interconnecting to the utility system. Connecting single-phase gensets to the utility system presents some interesting technical issues that have not been previously investigated. This paper addresses several of the interconnection issues associated with this form of DG including voltage regulation, harmonics, overcurrent protection, and islanding. A significant amount of single-phase DG can be accommodated by the utility distribution system, but there are definite limitations due to the nature and location of the DG. These limitations may be more restrictive than is commonly assumed for three-phase DG installed on stronger parts of the electric distribution system.
Date: December 5, 2001
Creator: Dugan, Roger C.
Object Type: Report
System: The UNT Digital Library