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open access

Power electronics reliability analysis.

Description: This report provides the DOE and industry with a general process for analyzing power electronics reliability. The analysis can help with understanding the main causes of failures, downtime, and cost and how to reduce them. One approach is to collect field maintenance data and use it directly to calculate reliability metrics related to each cause. Another approach is to model the functional structure of the equipment using a fault tree to derive system reliability from component reliability. Ana… more
Date: December 1, 2009
Creator: Smith, Mark A. & Atcitty, Stanley
Partner: UNT Libraries Government Documents Department
open access

Adaptive optics and phase diversity imaging for responsive space applications.

Description: The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the e… more
Date: November 1, 2004
Creator: Smith, Mark William & Wick, David Victor
Partner: UNT Libraries Government Documents Department
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Stressed Heat Affected Zone Simulations of AerMet 100 Alloy

Description: AerMet 100 is a high strength, high fracture toughness alloy designed for use in aerospace applications. In previous work the welding behavior of this alloy has been evaluated, and it has been shown that a softened region in the heat-affected zone (HAZ) is a principal feature of the weld zone. A model for this softening, based on classical theories of precipitate coarsening and isothermal softening data, was developed and found to provide a reasonable description for weld thermal cycle simulati… more
Date: August 3, 1999
Creator: Puskar, Joseph D. & Smith, Mark F.
Partner: UNT Libraries Government Documents Department
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Thermal spray and cold spray analysis of density, porosity, and tensile Specimens for use with LIGA applications

Description: This analysis provides a preliminary investigation into using Twin-Wire Arc Thermal Spray and Cold Spray as material deposition processes for LIGA applications. These spray material processes were studied to make an initial determination of their potential as alternatives to producing mechanical parts via the electroplating process. Three materials, UltraMachinable{reg_sign} Stainless Steel, BondArc{reg_sign}, and aluminum, were sprayed using Thermal Spray. Only aluminum was sprayed using the C… more
Date: February 1, 2000
Creator: Decker, Merlin K. & Smith, Mark F.
Partner: UNT Libraries Government Documents Department
open access

Stress Testing of the Philips 60W Replacement Lamp L Prize Entry

Description: The Pacific Northwest National Laboratory, operated by Battelle for the U.S. Department of Energy, worked with Intertek to develop a procedure for stress testing medium screw-base light sources. This procedure, composed of alternating stress cycles and performance evaluation, was used to qualitatively compare and contrast the durability and reliability of the Philips 60W replacement lamp L Prize entry with market-proven compact fluorescent lamps (CFLs) with comparable light output and functiona… more
Date: April 24, 2012
Creator: Poplawski, Michael E.; Ledbetter, Marc R. & Smith, Mark
Partner: UNT Libraries Government Documents Department
open access

Positron Emission Mammography with Multiple Angle Acquisition

Description: Positron emission mammography (PEM) of F-18 fluorodeoxyglucose (FDG) uptake in breast tumors with dedicated detectors typically has been accomplished with two planar detectors in a fixed position with the breast under compression. The potential use of PEM imaging at two detector positions to guide stereotactic breast biopsy has motivated us to use PEM coincidence data acquired at two or more detector positions together in a single image reconstruction. Multiple angle PEM acquisition and iterati… more
Date: November 1, 2002
Creator: Smith, Mark F.; Majewski, Stan & Raylman, Raymond R.
Partner: UNT Libraries Government Documents Department
open access

Optimizing Pinhole and Parallel Hole Collimation for Scintimammography With Compact Pixellated Detectors

Description: The relative resolution and sensitivity advantages of pinhole and parallel hole collimators for planar scintimammography with compact, pixellated gamma detectors were investigated using analytic models. Collimator design was studied as follows. A desired object resolution was specified for a pixellated detector with a given crystal size and intrinsic spatial resolution and for a given object-to- collimator distance. Using analytic formulas, pinhole and parallel hole collimator parameters were c… more
Date: November 1, 2002
Creator: Smith, Mark F.; Majewski, Stan & Weisenberger, Andrew G.
Partner: UNT Libraries Government Documents Department
open access

Positron Emission Mammography with Multiple Angle Acquisition

Description: Positron emission mammography (PEM) of F-18 fluorodeoxyglucose (FbG) uptake in breast tumors with dedicated detectors typically has been accomplished with two planar detectors in a fixed position with the breast under compression. The potential use of PEM imaging at two detector positions to guide stereotactic breast biopsy has motivated us to use PEM coincidence data acquired at two or more detector positions together in a single image reconstruction. Multiple angle PEM acquisition and iterati… more
Date: November 1, 2002
Creator: Smith, Mark F.; Majewski, Stan & Raylman, Raymond R.
Partner: UNT Libraries Government Documents Department
open access

Forming Limits of Weld Metal in Aluminum Alloys and Advanced High-Strength Steels

Description: This work characterizes the mechanical properties of DP600 laser welded TWBs (1 mm-1.5 mm) near and in the weld, as well as their limits of formability. The approach uses simple uniaxial experiments to measure the variability in the forming limits of the weld region, and uses a theoretical forming limit diagram calculation to establish a probabilistic distribution of weld region imperfection using an M-K method approach
Date: October 25, 2010
Creator: Stephens, Elizabeth V.; Smith, Mark T.; Grant, Glenn J. & Davies, Richard W.
Partner: UNT Libraries Government Documents Department
open access

Optimizing Pinhole and Parallel Hole Collimation for Scintimammography with Compact Pixellated Detectors

Description: The relative advantages of pinhole and parallel hole collimators for scintimammography with compact, pixellated gamma detectors were investigated using analytic models of resolution and sensitivity. Collimator design was studied as follows. A desired object resolution was specified for a pixellated detector with a given crystal size and intrinsic spatial resolution and for a given object-to-collimator distance. Using analytic formulas, pinhole and parallel hole collimator parameters were calcul… more
Date: November 1, 2002
Creator: Smith, Mark F.; Kieper, Douglas A.; Majewski, Stan; Weisenberger, Andrew G. & Welch, Benjamin
Partner: UNT Libraries Government Documents Department
open access

Stress testing on silicon carbide electronic devices for prognostics and health management.

Description: Power conversion systems for energy storage and other distributed energy resource applications are among the drivers of the important role that power electronics plays in providing reliable electricity. Wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) will help increase the performance and efficiency of power electronic equipment while condition monitoring (CM) and prognostics and health management (PHM) will increase the operational availability of the equip… more
Date: January 1, 2011
Creator: Kaplar, Robert James; Brock, Reinhard C.; Marinella, Matthew; King, Michael Patrick; Smith, Mark A. & Atcitty, Stanley
Partner: UNT Libraries Government Documents Department
open access

Effect of high magnetic fields on orientation and properties of liquid crystalline thermosets

Description: In this report we provide the first description of the orientation of liquid crystalline thermosets (LCT`s) in field strengths of up to 18 T, as well as the first report of tensile properties for both unoriented and oriented LCT`S. The LCT we have chosen for study is the diglycidyl ether of dihydroxy-a-methylstilbene cured with the diamine, sulfanilamide. Orientation in magnetic fields leads to an increase of almost three times the modulus compared to the unoriented material. These values are m… more
Date: February 1, 1996
Creator: Smith, Mark E.; Benicewicz, Brian C.; Douglas, Elliot P.; Earls, Jim D. & Priester, Ralph D., Jr.
Partner: UNT Libraries Government Documents Department
open access

Processing of polymers in high magnetic fields

Description: Many organic molecules and polymers have an anisotropic diamagnetic susceptibility, and thus can be aligned in high magnetic fields. The presence of liquid crystallinity allows cooperative motions of the individual molecules, and thus the magnetic energy becomes greater than the thermal energy at experimentally obtainable field strengths. This work has determined the effect of magnetic field alignment on the thermal expansion and mechanical properties of liquid crystalline thermosets in the lab… more
Date: May 1, 1996
Creator: Douglas, Elliot P.; Smith, Mark E.; Benicewicz, Brian C.; Earls, Jim D. & Priester, Ralph D., Jr.
Partner: UNT Libraries Government Documents Department
open access

Design of High Sensitivity, High Resolution Compact Single Photon Imaging Devices for Small Animal and Dedicated Breast Imaging

Description: Imaging the biodistribution of single photon emitting radiotracers in small animals and in the breast with high resolution and high sensitivity is an important challenge. Recent work has shown that single photon emission computed tomography (SPECT) imaging of small objects with coded aperture collimators and iterative image reconstruction may provide an order of magnitude increase in sensitivity yet maintain high spatial resolution. We propose a new system design with compact detectors for sing… more
Date: December 1, 2001
Creator: Smith, Mark F.; Majewski, Stan; Meikle, Steven R.; Weisenberger, Andrew G.; Popov, Vladmimir & Wojcik, Randolph F.
Partner: UNT Libraries Government Documents Department
open access

Design of High Sensitivity, High Resolution Compact Single Photon Imaging Devices for Small Animal and Dedicated Breast Imaging

Description: Imaging the biodistribution of single photon emitting radiotracers in small animals and in the breast with high resolution and high sensitivity is an important challenge. Recent work has shown that single photon emission computed tomography (SPECT) imaging of small objects with coded aperture collimators and iterative image reconstruction may provide an order of magnitude increase in sensitivity yet maintain high spatial resolution. We propose a new system design with compact detectors for sing… more
Date: November 1, 2001
Creator: Smith, Mark F.; Majewski, Stan; Meikle, Steven R.; Weisenberger, Andrew G.; Popov, Vladimir & Wojcik, Randolph F.
Partner: UNT Libraries Government Documents Department
open access

High modulus liquid crystalline thermosetting resins through novel processing techniques

Description: The authors have demonstrated the effects of magnetic field alignment for the epoxy resin system, the diglycidyl ether of dihydroxy-{alpha}-methylstilbene cured with sulfanilamide. With increasing magnetic field, the tensile modulus of the thermoset can be enhanced by a factor of three, without compromise to the transverse value. Measurements of the coefficients of thermal expansion and the order parameter as determined by x-ray diffraction elucidate the high degree of alignment obtained at fie… more
Date: May 1, 1996
Creator: Smith, Mark E.; Douglas, Elliot P.; Benicewicz, Brian C.; Earls, J. D. & Priester, R. D., Jr.
Partner: UNT Libraries Government Documents Department
open access

Analysis of Factors Affecting Positron Emission Mammography (PEM) Image Formation

Description: Image reconstruction for positron emission mammography (PEM) with the breast positioned between two parallel, planar detectors is usually performed by backprojection to image planes. Three important factors affecting PEM image reconstruction by backprojection are investigated: (1) image uniformity (flood) corrections, (2) image sampling (pixel size) and (3) count allocation methods. An analytic expression for uniformity correction is developed that incorporates factors for spatial-dependent det… more
Date: November 1, 2001
Creator: Smith, Mark F.; Majewski, Stan; Weisenberger, Andrew G.; Kieper, Douglas A.; Raylman, Raymond R. & Turkington, Timothy G.
Partner: UNT Libraries Government Documents Department
open access

High Speed 2D Hadamard Transform Spectral Imager

Description: Hadamard Transform Spectrometer (HTS) approaches share the multiplexing advantages found in Fourier transform spectrometers. Interest in Hadamard systems has been limited due to data storage/computational limitations and the inability to perform accurate high order masking in a reasonable amount of time. Advances in digital micro-mirror array (DMA) technology have opened the door to implementing an HTS for a variety of applications including fluorescent microscope imaging and Raman imaging. A H… more
Date: February 1, 2003
Creator: WEHLBURG, JOSEPH C.; WEHLBURG, CHRISTINE M.; SMITH, JODY L.; SPAHN, OLGA B.; SMITH, MARK W. & BONEY, CRAIG M.
Partner: UNT Libraries Government Documents Department
open access

Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

Description: This report describes the status of the current process modeling approaches to predict the behavior and flow of fiber-filled thermoplastics under injection molding conditions. Previously, models have been developed to simulate the injection molding of short-fiber thermoplastics, and an as-formed composite part or component can then be predicted that contains a microstructure resulting from the constituents’ material properties and characteristics as well as the processing parameters. Our object… more
Date: November 30, 2006
Creator: Nguyen, Ba Nghiep; Holbery, Jim; Smith, Mark T.; Kunc, Vlastimil; Norris, Robert E.; Phelps, Jay et al.
Partner: UNT Libraries Government Documents Department
open access

Global Land Project: Science Plan and ImplementationStrategy

Description: The Global Land Project (GLP) Science Plan and Implementation Strategy represents the joint research agenda of IGBP and IHDP to improve the understanding of land system dynamics in the context of Earth System functioning. This plan is therefore a first critical step in addressing the interaction between people and their environments. It is part of the broader efforts to understand how these interactions have affected, and may yet affect, the sustainability of the terrestrial biosphere, and the … more
Date: September 2005
Creator: Global Land Project (GLP)
Partner: UNT Libraries
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