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DEPOT: A Database of Environmental Parameters, Organizations and Tools (open access)

DEPOT: A Database of Environmental Parameters, Organizations and Tools

The Database of Environmental Parameters, Organizations, and Tools (DEPOT) has been developed by the Department of Energy (DOE) as a central warehouse for access to data essential for environmental risk assessment analyses. Initial efforts have concentrated on groundwater and vadose zone transport data and bioaccumulation factors. DEPOT seeks to provide a source of referenced data that, wherever possible, includes the level of uncertainty associated with these parameters. Based on the amount of data available for a particular parameter, uncertainty is expressed as a standard deviation or a distribution function. DEPOT also provides DOE site-specific performance assessment data, pathway-specific transport data, and links to environmental regulations, disposal site waste acceptance criteria, other environmental parameter databases, and environmental risk assessment models.
Date: December 19, 2000
Creator: CARSON, SUSAN D.; Hunter, Regina Lee; Malczynski, Leonard A.; POHL, PHILLIP I.; Quintana, Enrico; Souza, Caroline A. et al.
System: The UNT Digital Library
Impedance behavior of the LiMn2O4/LiPF6-DMC-EC interface during cycling (open access)

Impedance behavior of the LiMn2O4/LiPF6-DMC-EC interface during cycling

Room temperature impedance measurements of the LiMn2O4/LiPF6-EC-DMC interface have been used to identify a previously unreported step in the formation of the SEI layer on this cathode. The low frequency impedance and potential of pure dense LiMn2O4 films was found to depend logarithmically on time in the end-of-discharge (EOD) state. The rate of the impedance rise decreased with Mn3+ content. The increased impedance was removed by oxidation of the film to 4.5 V vs. Li/Li+. The observations are consistent with a reversible disproportionation of part of the LiMn2O4 into Li2Mn2O4 and l-Mn2O4. Analyses of cyclic voltammograms and impedance spectra at intervals during constant current cycling of the LiMn2O4 films suggest that Li2Mn2O4 on the surface also plays a major role in the capacity fade.
Date: December 19, 2000
Creator: Striebel, Kathryn A.; Sakai, Eiji & Cairns, Elton J.
System: The UNT Digital Library
Internet-Based Calibration of a Multifunction Calibrator (open access)

Internet-Based Calibration of a Multifunction Calibrator

A new way of providing calibration services is evolving which employs the Internet to expand present capabilities and make the calibration process more interactive. Sandia National Laboratories and the National Institute of Standards and Technology are collaborating to set up and demonstrate a remote calibration of multijunction calibrators using this Internet-based technique that is becoming known as e-calibration. This paper describes the measurement philosophy and the Internet resources that can provide real-time audio/video/data exchange, consultation and training, as well as web-accessible test procedures, software and calibration reports. The communication system utilizes commercial hardware and software that should be easy to integrate into most calibration laboratories.
Date: December 19, 2000
Creator: Bunting Baca, Lisa A.; Duda, Leonard E., Jr.; Walker, Russell M.; Oldham, Nile & Parker, Mark
System: The UNT Digital Library
A Semi-Analytical Solution for Steady Infiltration in Unsaturated Fractured Rock (open access)

A Semi-Analytical Solution for Steady Infiltration in Unsaturated Fractured Rock

A semi-analytical solution is developed for one-dimensional steady infiltration in unsaturated fractured rock. The differential form of the mass conservation equation is integrated to yield an analytical expression relating elevation to a function of capillary pressure and relative permeability of the fracture and rock matrix. Constitutive relationships for unsaturated flow in this analysis are taken from van Genuchten [1980] and Mualem [1976], but alternative relations can also be implemented in the integral solution. Expressions are presented for the liquid saturations and pore velocities in the fracture, matrix, and effective continuum materials as a function of capillary pressure and elevation. Results of the analytical solution are applied to examples of infiltration in fractured rock consisting of both homogeneous and composite (layered) domains. The analytical results are also compared to numerical simulations to demonstrate the use of the analytical solution as a benchmarking tool to address computational issues such as grid refinement.
Date: December 19, 2000
Creator: HO,CLIFFORD K.
System: The UNT Digital Library
X-Ray Powder Diffraction Study of Synthetic Palmierite, K{sub 2}Pb(SO{sub 4}){sub 2} (open access)

X-Ray Powder Diffraction Study of Synthetic Palmierite, K{sub 2}Pb(SO{sub 4}){sub 2}

Palmierite (K{sub 2}Pb(SO{sub 4}){sub 2}) has been prepared via a chemical synthesis method. Intensity differences were observed when X-ray powder data from the newly synthesized compound were compared to the published powder diffraction card (PDF) 29-1015 for Palmierite. Investigation of these differences indicated the possibility of preferred orientation and/or chemical inhomogeneity affecting intensities, particularly those of the basal (00{ell}) reflections. Annealing of the Palmierite was found to reduce the effects of preferred orientation. Electron microprobe analysis confirmed K:Pb:S as 2:1:2 for the annealed Palmierite powder. Subsequent least-squares refinement and Rietveld analysis of the annealed powder showed peak intensities very close to that of a calculated Palmierite pattern (based on single crystal data), yet substantially higher than many of the PDF 29-1015 published intensities. Further investigation of peak intensity variation via calculated patterns suggested that the intensity discrepancies between the annealed sample and those found in PDF 29-1015 were potentially due to chemical variation in the K{sub 2}Pb(SO{sub 4}){sub 2} composition. X-ray powder diffraction and crystal data for Palmierite are reported for the annealed sample. Palmierite is Trigonal/Hexagonal with unit cell parameters a = 5.497(1){angstrom}, c = 20.864(2) {angstrom}, space group R-3m (166), and Z = 3.
Date: December 19, 2000
Creator: Tissot, Ralph G., Jr.; Rodriguez, Mark A.; Sipola, Diana L. & Voigt, James A.
System: The UNT Digital Library