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Adaptable Multivariate Calibration Models for Spectral Applications (open access)

Adaptable Multivariate Calibration Models for Spectral Applications

Multivariate calibration techniques have been used in a wide variety of spectroscopic situations. In many of these situations spectral variation can be partitioned into meaningful classes. For example, suppose that multiple spectra are obtained from each of a number of different objects wherein the level of the analyte of interest varies within each object over time. In such situations the total spectral variation observed across all measurements has two distinct general sources of variation: intra-object and inter-object. One might want to develop a global multivariate calibration model that predicts the analyte of interest accurately both within and across objects, including new objects not involved in developing the calibration model. However, this goal might be hard to realize if the inter-object spectral variation is complex and difficult to model. If the intra-object spectral variation is consistent across objects, an effective alternative approach might be to develop a generic intra-object model that can be adapted to each object separately. This paper contains recommendations for experimental protocols and data analysis in such situations. The approach is illustrated with an example involving the noninvasive measurement of glucose using near-infrared reflectance spectroscopy. Extensions to calibration maintenance and calibration transfer are discussed.
Date: December 20, 1999
Creator: THOMAS,EDWARD V.
System: The UNT Digital Library
Extracellular iron-sulfur precipitates from growth of Desulfovibrio desulfuricans (open access)

Extracellular iron-sulfur precipitates from growth of Desulfovibrio desulfuricans

The authors have examined extracellular iron-bearing precipitates resulting from the growth of Desulfovibrio desulfuricans in a basal medium with lactate as the carbon source and ferrous sulfate. Black precipitates were obtained when D. desulfuricans was grown with an excess of FeSO{sub 4}. When D. desulfuricans was grown under conditions with low amounts of FeSO{sub 4}, brown precipitates were obtained. The precipitates were characterized by iron K-edge XAFS (X-ray absorption fine structure), {sup 57}Fe Moessbauer-effect spectroscopy, and powder X-ray diffraction. Both were noncrystalline and nonmagnetic (at room temperature) solids containing high-spin Fe(III). The spectroscopic data for the black precipitates indicate the formation of an iron-sulfur phase with 6 nearest S neighbors about Fe at an average distance of 2.24(1) {angstrom}, whereas the brown precipitates are an iron-oxygen-sulfur phase with 6 nearest O neighbors about Fe at an average distance of 1.95(1) {angstrom}.
Date: December 20, 1999
Creator: Antonio, M. R.; Tischler, M. L. & Witzcak, D.
System: The UNT Digital Library
Glass, Plastic and Semiconductors: Packaging Techniques for Miniature Optoelectric Components (open access)

Glass, Plastic and Semiconductors: Packaging Techniques for Miniature Optoelectric Components

At Lawrence Livermore National Laboratory, they have extensive experience with the design and development of miniature photonic systems which require novel packaging schemes. Over the years they have developed silicon micro-optical benches to serve as a stable platform for precision mounting of optical and electronic components. They have developed glass ball lenses that can be fabricated in-situ on the microbench substrate. They have modified commercially available molded plastic fiber ribbon connectors (MT) and added thin film multilayer semiconductor coatings to create potentially low-cost wavelength combiners and wavelength selective filters. They have fabricated both vertical-cavity and in-plane semiconductor lasers and amplifiers, and have packaged these and other components into several miniature photonics systems. For example, they have combined the silicon optical bench with standard electronic packaging techniques and the custom-made wavelength-selective filters to develop a four-wavelength wavelength-division-multiplexing transmitter module mounted in a standard 120-pin ceramic PGA package that couples light from several vertical-cavity-surface-emitting-laser arrays into one multimode fiber-ribbon array. The coupling loss can be as low as 2dB, and the transmitters can be operated at over 1.25 GHz. While these systems were not designed for biomedical or environmental applications, the concepts and techniques are general and widely applicable.
Date: December 20, 1999
Creator: Pocha, M. D.; Garrett, H. E.; Patel, R. R.; Jones, L. M., II; Larson, M. C.; Emanuel, M. A. et al.
System: The UNT Digital Library
The influence of desulfovibrio desulfuricans on neptunium chemistry. (open access)

The influence of desulfovibrio desulfuricans on neptunium chemistry.

The role of biotic Np(V) reduction is studied in light of its potential role in the environmental immobilization of this hazardous radionuclide. The speciation of Np in Desulfovibrio desulfuricans cultures is compared with Np speciation in the spent medium and in the uninoculated medium. Precipitates formed in all three samples. Optical spectroscopy and X-ray absorption near edge structure (XANES) were used to determine that Np(V) is almost quantitatively reduced in all three samples and that the precipitate is an amorphous Np(IV) species. These results demonstrate that the reduction of Np is independent of Desulfovibrio desulfuricans. The underlying chemistry associated with these results is discussed.
Date: December 20, 1999
Creator: Soderholm, L.; Williams, C.; Antonio, M. R.; Tischler, M. L. & Markos, M.
System: The UNT Digital Library
Influence of Processing Method on the Grain Boundary Character Distribution and Network Connectivity (open access)

Influence of Processing Method on the Grain Boundary Character Distribution and Network Connectivity

There exists a growing body of literature that correlates the fraction of ''special'' boundaries in a microstructure, as described by the Coincident Site Lattice Model, to properties such as corrosion resistance, intergranular stress corrosion cracking, creep, etc. Several studies suggest that the grain boundary character distribution (GBCD), which is defined in terms of the relative fractions of ''special'' and ''random'' grain boundaries, can be manipulated through thermomechanical processing. This investigation evaluates the influence of specific thermomechanical processing methods on the resulting GBCD in FCC materials such as oxygen-free electronic (ofe) copper and Inconel 600. We also demonstrate that the primary effect of thermomechanical processing is to reduce or break the connectivity of the random grain boundary network. Samples of ofe Cu were subjected to a minimum of three different deformation paths to evaluate the influence of deformation path on the resulting GBCD. These include: rolling to 82% reduction in thickness, compression to 82% strain, repeated compression to 20% strain followed by annealing. In addition, the influence of annealing temperature was probed by applying, for each of the processes, three different annealing temperatures of 400, 560, and 800 C. The observations obtained from automated electron backscatter diffraction (EBSD) characterization of the …
Date: December 20, 1999
Creator: Kumar, M & King, W.E.
System: The UNT Digital Library
Nuclear structure of the Cd and Te nuclei: Akin to tin or a breed apart? (open access)

Nuclear structure of the Cd and Te nuclei: Akin to tin or a breed apart?

Many of the {sub 48}Cd nuclei are good examples of U(5) or vibrational nuclei. Like the {sub 50}Sn nuclei and others in the region, states exist which are interpreted in terms of the excitation of a pair of protons across the shell gap (intruders). The features of the comparatively well-understood Cd nuclei will be considered and compared with the{sub 52}Te nuclei where intruders have not been identified experimentally and problems exist with the U(5) interpretation.
Date: December 20, 1999
Creator: Garrett, P E; Warr, N & Hicks, S F
System: The UNT Digital Library
Performance of a high-resolution x-ray microprobe at the Advanced Photon Source. (open access)

Performance of a high-resolution x-ray microprobe at the Advanced Photon Source.

The authors have developed a x-ray microprobe in the energy region from 6 to 20 keV using undulator radiation and zone-plate optics for microfocusing-based techniques and applications at a beamline at the Advanced Photon Source (APS). The performance of the beamline was shown to meet the design objectives, including preservation of the source brilliance and coherence, selectable transverse coherence length and energy bandwidth, high angular stability, and harmonic suppression of the beam. These objectives were achieved by careful thermal management and use of a novel mirror and crystal monochromator cooling geometry. All beamline optical components are water cooled, and the x-ray beam in the experiment station is stable in beam intensity, energy, and position over many days with no active feedback. Using a double-crystal Si(111) monochromator, they have obtained a focal spot size (FWHM) of 0.15 {micro}m (v) x 1.0 {micro}m (h), and a photon flux of 4 x 10{sup 9} photons/sec at the focal spot, and thus a photon flux density gain of 15,000. A circular beam spot of 0.15 {micro}m in diameter can be achieved by reducing the horizontal source size using a white beam slit located 43.5 meters upstream of the zone plate, with an order of …
Date: December 20, 1999
Creator: Cai, Z.; Lai, B.; Yun, W.; McNulty, I.; Khounsary, A.; Maser, J. et al.
System: The UNT Digital Library
Performance of hard X-ray zone plates at the Advanced Photon Source (open access)

Performance of hard X-ray zone plates at the Advanced Photon Source

Fresnel zone plates have been highly successful as focusing and imaging optics for soft x-ray microscopes and microprobe. More recently, with the advent of third-generation high-energy storage rings, zone plates for the hard x-ray regime have been put to use as well. The performance of zone plates manufactured using a combination of electron-beam lithography and x-ray lithography is described.
Date: December 20, 1999
Creator: Maser, J.; Lai, B.; Cai, Z.; Rodrigues, W.; Legnini, D.; Ilinski, P. et al.
System: The UNT Digital Library
Resonance X-ray scattering from Pt(111) surfaces under water (open access)

Resonance X-ray scattering from Pt(111) surfaces under water

The resonance X-ray scattering from the unmodified, clean Pt(111) surface is compared to theoretically predicted scattering. Self-consistent real-space multiple-scattering approach is used to calculate the real and imaginary parts of the atomic platinum scattering factor. The experimentally observed near-edge fine structures of the surface-scattering and fluorescence intensities are well reproduced by the calculations. In addition, more details are presented on their previous study [Phys.Rev.Lett. 83, 552 (1999)] of electrochemically formed oxide monolayer on the Pt(111) surface.
Date: December 20, 1999
Creator: You, H.; Chu, Y. S.; Lister, T. E.; Nagy, Z.; Ankudiniv, A. L. & Rehr, J. H.
System: The UNT Digital Library
{sup 170}Er: The search for multiphonon vibrations in a rotational nucleus (open access)

{sup 170}Er: The search for multiphonon vibrations in a rotational nucleus

To search for candidates for 2-phonon vibrations, {sup 170}Er was studied with the inelastic neutron scattering reaction. The level scheme was extended using {gamma}{gamma} coincidences and excitation functions. Spins were deduced from angular distribution measurements, and the Doppler-shift attenuation method (DSAM) was used to determine lifetimes.
Date: December 20, 1999
Creator: Garrett, P.; Warr, N.; Brown, T. B. & Martin, A.
System: The UNT Digital Library
Material Failure and the Growth of Instabilities in Hollow Cylindrical Samples of Aluminum Shocked to 14Gpa and 50Gpa (U) (open access)

Material Failure and the Growth of Instabilities in Hollow Cylindrical Samples of Aluminum Shocked to 14Gpa and 50Gpa (U)

Understanding the surface stability of metals undergoing dynamic fracture at shock breakout is important to several applications in metals processing. The advantages of using the Pegasus II facility to investigate the phenomena occurring at shock break out are described. As an example of the data collected, we concentrate on brief descriptions of two experiments that compared the tensile failure, i.e. ''spall'', patterns in the presence of sinusoidal perturbations seeded on the free inner surface of cylindrical samples made of structural grade Al 6061.T6. These samples were subjected to ramped waves with shock pressures of 14 GPa and 50 GPa to observe the effect of pressure on the production of a type of volumetric failure that is mentioned here ''microspall.'' This failed region behind the exiting surface of the shock wave is comprised of a significant volume of low-density, probably granular, material. The failure mechanism, combined with the forces that cause inertial instability, leads to rapid pattern growth in the failed material, observable as density variations, as well as to pattern growth on the surface. Pattern growth was observed to vary with perturbation amplitude, wavelength, and shock pressure. Both increased pressure and increased amplitude were shown to destabilize a stable perturbation. …
Date: November 20, 1999
Creator: Stokes, J.; Fulton, R. D.; Morgan, D. V.; Obst, A. W.; Oro, D. M.; Oona, H. et al.
System: The UNT Digital Library
Certification testing for small wind turbines (open access)

Certification testing for small wind turbines

This paper describes the testing procedures for obtaining type certification for a small wind turbine. Southwest Windpower (SWWP) is seeking type certification from Underwriters Laboratory (UL) for the AIR 403 wind turbine. UL is the certification body and the National Renewable Energy Laboratory (NREL) is providing technical assistance including conducting the certification testing. This is the first small turbine to be certified in the US, therefore standards must be interpreted and test procedures developed.
Date: October 20, 1999
Creator: Corbus, D.; Link, H.; Butterfield, S.; Stork, C. & Newcomb, C.
System: The UNT Digital Library
Cone Penetrometer Off-Surface Sensor (open access)

Cone Penetrometer Off-Surface Sensor

Cone penetrometer technology accounts for approximately 50 percent of the subsurface drilling done at the Savannah River Site. This technology provides a means of collecting data for use in the characterization of the subsurface. The cone penetrometer consists of a steel cone attached to a pipe column that is hydraulically inserted into the ground. To allow researchers to accurately measure subsurface properties, without the inherent problems of cone penetrometer equipment, the Savannah River Technology Center has developed the Cone Penetrometer Off-Surface Sensor (CPOSS). The CPOSS design consists of a knife-blade mechanism mounted along the surface of a module capable of attaching to existing cone penetrometer equipment and being deployed at depths of up to 200 feet. CPOSS development is the subject of this report.
Date: October 20, 1999
Creator: Smail, T. R.; French, P. J.; Huffman, R. K. & Hebert, P. S.
System: The UNT Digital Library
Current Issues in Terrestrial Solar Radiation Instrumentation for Energy, Climate and Space Applications Preprint prepared for New RAD '99 (open access)

Current Issues in Terrestrial Solar Radiation Instrumentation for Energy, Climate and Space Applications Preprint prepared for New RAD '99

Reductions of uncertainty in terrestrial solar radiation measurements are needed to validate the Earth's radiation balance derived from satellite data. Characterization of solar energy resources for renewable technologies requires greater time and spatial resolution for economical technology deployment. Solar radiation measurement research at the National Renewable Energy Laboratory addresses calibrations, operational characteristics, and corrections for terrestrial solar radiation measurements. We describe progress in measurements of broadband diffuse-sky radiation, and characterization of field instrument thermal offsets and spectral irradiance. The need and prospects for absolute references for diffuse and long-wave terrestrial solar radiation measurements are discussed. Reductions in uncertainty of broadband irradiance measurements from tens of watts per square meter to a few (one to two) watts per square meter are reported, which reduce time and labor to quantify and identify trends in artificial optical radiation sources, terrestrial solar radiation, and the Earth's radiation budget.
Date: October 20, 1999
Creator: Stoffel, T. L.; Reda, I.; Myers, D. R.; Renne, D.; Wilcox, S. W. & Treadwell, J.
System: The UNT Digital Library
Evaluation of cracking in the 241-AZ tank farm ventilation line at the Hanford Site (open access)

Evaluation of cracking in the 241-AZ tank farm ventilation line at the Hanford Site

In the period from April to October of 1988, a series of welding operations on the outside of the AZ Tank Farm ventilation line piping at the Hanford Site produced unexpected and repeated cracking of the austenitic stainless steel base metal and of a seam weld in the pipe. The ventilation line is fabricated from type 304L stainless steel pipe of 24 inch diameter and 0.25 inch wall thickness. The pipe was wrapped in polyethylene bubble wrap and buried approximately 12 feet below grade. Except for the time period between 1980 and 1987, impressed current cathodic protection has been applied to the pipe since its installation in 1974. The paper describes the history of the cracking of the pipe, the probable cracking mechanisms, and the recommended future action for repair/replacement of the pipe.
Date: October 20, 1999
Creator: ANANTATMULA, R.P.
System: The UNT Digital Library
An Evaluation of Power Law Breakdown in Metals, Alloys, Dispersion Hardened Materials and Compounds (open access)

An Evaluation of Power Law Breakdown in Metals, Alloys, Dispersion Hardened Materials and Compounds

Creep at high stresses often produces strain rates that exceed those that would be predicted by a power law relationship. In this paper, we examine available high stress creep data for pure metals, solid solution alloys, dispersion strengthened powder metallurgy materials and compounds for power law breakdown (PLB). The results show that, if PLB is observed, then the onset of PLB is generally observed at about {epsilon}/D{sub eff} = 10{sup 13} m{sup -2}, where D{sub eff} is the effective diffusion coefficient incorporating lattice and dislocation pipe diffusion. The common origins of PLB for the various systems studied can be found in the production of excess vacancies by plastic deformation. Anomalous behavior in two pure metals (nickel and tungsten) and a solid solution alloy (Fe-25Cr and Fe-26Cr-1Mo) has been analyzed and provides insight into this excess vacancy mechanism. In metal systems, the onset of PLB is related to a change in the nature of the subgrain structure developed. In the PLB region, subgrains become imperfect containing dislocation tangles adjacent to the sub-boundary, and dislocation cells are evident. The dislocation tangles and cells are the source of excess vacancies and increase the creep rate above that predicted from power law creep. If …
Date: October 20, 1999
Creator: Lesuer, D. R.; Syn, C. K. & Sherby, O. D.
System: The UNT Digital Library
Hydrogen Peroxide Storage in Small Sealed Tanks (open access)

Hydrogen Peroxide Storage in Small Sealed Tanks

Unstabilized hydrogen peroxide of 85% concentration has been prepared in laboratory quantities for testing material compatibility and long term storage on a small scale. Vessels made of candidate tank and liner materials ranged in volume from 1 cc to 2540 cc. Numerous metals and plastics were tried at the smallest scales, while promising ones were used to fabricate larger vessels and liners. An aluminum alloy (6061-T6) performed poorly, including increasing homogeneous decay due to alloying elements entering solution. The decay rate in this high strength aluminum was greatly reduced by anodizing. Better results were obtained with polymers, particularly polyvinylidene fluoride. Data reported herein include ullage pressures as a function of time with changing decay rates, and contamination analysis results.
Date: October 20, 1999
Creator: Whitehead, J.
System: The UNT Digital Library
Intelligent Microsystems: Keys to the Next Silicon Revolution (open access)

Intelligent Microsystems: Keys to the Next Silicon Revolution

Paul McWhorter, Deputy Director for of the Microsystems Center at Sandia National Laboratories, discusses the potential of surface micromachining. A vision of the possibilities of intelligent Microsystems for the future is presented along with descriptions of several possible applications. Applications that are just around the corner and some that maybe quite a ways down the road but have a clear development path to their realization. Microsystems will drive the next silicon revolution.
Date: October 20, 1999
Creator: MCWHORTER,PAUL J.
System: The UNT Digital Library
Laboratory Velocity Measurements Used for Recovering Soil Distributions from Field Seismic Data (open access)

Laboratory Velocity Measurements Used for Recovering Soil Distributions from Field Seismic Data

Recent advances in field methods make it possible to obtain high quality compressional (P) and shear (S) velocity data for the shallow subsurface. Environmental and engineering problems require new methods for interpreting the velocity data in terms of sub-surface soil distribution. Recent advances in laboratory measurement techniques have provided high quality velocity data for soils at low pressures that can be used to improve interpretation of field data. We show how laboratory data can be used to infer lithology from field data. We use laboratory ultrasonic velocity measurements from artificial soils made by combining various amounts of sand and peat moss.
Date: October 20, 1999
Creator: Berge, P A & Bertete-Aguirre, H
System: The UNT Digital Library
Laser ablation studies of concrete (open access)

Laser ablation studies of concrete

Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.
Date: October 20, 1999
Creator: Savina, M.; Xu, Z.; Wang, Y.; Reed, C. & Pellin, M.
System: The UNT Digital Library
Modeling access to wind resources in the United States (open access)

Modeling access to wind resources in the United States

To project the US potential to meet future electricity demands with wind energy, estimates of available wind resource and costs to access that resource are critical. The US Department of Energy (DOE) Energy Information Administration (EIA) annually estimates the US market penetration of wind in its Annual Energy Outlook series. For these estimates, the EIA uses wind resource data developed by the Pacific Northwest National Laboratory for each region of the country. However, the EIA multiplies the cost of windpower by several factors, some as large as 3, to account for resource quality, market factors associated with accessing the resource, electric grid impacts, and rapid growth in the wind industry. This paper examines the rationale behind these additional costs and suggests alternatives.
Date: October 20, 1999
Creator: Short, W. D.
System: The UNT Digital Library
Nanoparticle derived contacts for photovoltaic cells (open access)

Nanoparticle derived contacts for photovoltaic cells

Contacts are becoming increasingly important as PV devices move to higher efficiency and lower cost. The authors present an approach to developing contacts using nanoparticle-based precursors. Both elemental, alloy and compound nanoparticles can be employed for contacts. Ink based approaches can be utilized at low temperatures and utilize direct write techniques such as ink jet and screen printing. The ability to control the composition of the nanoparticle allows improved control of the contact metallurgy and the potential for thermodynamically stable interfaces. A key requirement is the ability to control the interface between particles and between particles and the substrate. The authors illustrate some of these principals with recent results on Al, Cu and (Hg,Cu)Te. They show that for the elemental materials control of the surface can prevent oxide formation and act as glue to control the reactivity of the nanoparticles.
Date: October 20, 1999
Creator: Ginley, D.S.
System: The UNT Digital Library
Quark confinement and surface critical phenomena (open access)

Quark confinement and surface critical phenomena

Surface critical phenomena and the related onset of Goldstone modes probe the fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement are presented. Problems with the oversimplified string description of the Wilson flux sheet are discussed.
Date: October 20, 1999
Creator: K.J. Juge, J. Kuti and C.J. Morningstar
System: The UNT Digital Library
Supergravity inspired warped compactifications and effectivecosmological constants (open access)

Supergravity inspired warped compactifications and effectivecosmological constants

None
Date: October 20, 1999
Creator: Grojean, C.; Cline, J. & Servant, G.
System: The UNT Digital Library