Dimensional Measurements of Three Tubes by Computed Tomography (open access)

Dimensional Measurements of Three Tubes by Computed Tomography

Low density polyethylene (LDPE), copper (Cu), and gold (Au) tubes were scanned on KCAT to identify and evaluate the impact of phase effects on quantitative object recovery. These tubes are phantoms for high energy density capsules.[Logan, et al. 2004] Digital radiographs for each tube are shown in Figure 1. The LDPE tube was scanned at 60 kV, while the Cu and the Au tubes were scanned at 140 kV. All tubes were scanned at a magnification of 3, with approximately 100-mm distance between the exit plane of the tube and the scintillator. Notice the prominence of the outer bright and inner dark edges for the LDPE tube DR, and their absence from the Cu and Au tube DRs. The bright and dark edges are a result of change in phase of the x-rays. The x-ray fluence is partly attenuated and partly refracted. The location near the outer edge of the tube appears to be more attenuating since those x-rays have refracted to locations just outside the tube. Alternatively, the added counts from the refraction result in intensities that are greater than the incident intensity effectively representing a ''negative attenuation''. This results in more counts in that location than in the …
Date: October 5, 2004
Creator: Schneberk, D. J.; Martz, H. E., Jr. & Brown, W. D.
Object Type: Report
System: The UNT Digital Library
Marginal Stability Diagrams for Infinite-n Ballooning Modes in Quasi-symmetric Stellarators (open access)

Marginal Stability Diagrams for Infinite-n Ballooning Modes in Quasi-symmetric Stellarators

By perturbing the pressure and rotational-transform profiles at a selected surface in a given equilibrium, and by inducing a coordinate variation such that the perturbed state is in equilibrium, a family of magnetohydrodynamic equilibria local to the surface and parameterized by the pressure gradient and shear is constructed for arbitrary stellarator geometry. The geometry of the surface is not changed. The perturbed equilibria are analyzed for infinite-n ballooning stability and marginal stability diagrams are constructed that are analogous to the (s; alpha) diagrams constructed for axi-symmetric configurations. The method describes how pressure and rotational-transform gradients influence the local shear, which in turn influences the ballooning stability. Stability diagrams for the quasi-axially-symmetric NCSX (National Compact Stellarator Experiment), a quasi-poloidally-symmetric configuration and the quasi-helically-symmetric HSX (Helically Symmetric Experiment) are presented. Regions of second-stability are observed in both NCSX and the quasi-poloidal configuration, whereas no second stable region is observed for the quasi-helically symmetric device. To explain the different regions of stability, the curvature and local shear of the quasi-poloidal configuration are analyzed. The results are seemingly consistent with the simple explanation: ballooning instability results when the local shear is small in regions of bad curvature. Examples will be given that show that …
Date: December 5, 2003
Creator: Hudson, S. R.; Hegna, C. C.; Torasso, R. & Ware, A.
Object Type: Report
System: The UNT Digital Library
International Efforts to Control the Spread of Avian Influenza (H5N1) Virus: Affected Countries' Responses (open access)

International Efforts to Control the Spread of Avian Influenza (H5N1) Virus: Affected Countries' Responses

This report examines the efforts of overseas governments to combat the spread of avian influenza H5N1 which first appeared in birds and humans in Hong Kong in 1997, causing 100 reported human deaths from Vietnam to Turkey and appearing in birds in Africa and Europe.
Date: April 5, 2006
Creator: Chanlett-Avery, Emma; Cook, Nicolas; Dumbaugh, Kerry; Lum, Thomas; Manyin, Mark E.; Nichol, Jim et al.
Object Type: Report
System: The UNT Digital Library
Presidential Claims of Executive Privilege: History, Law, Practice and Recent Developments (open access)

Presidential Claims of Executive Privilege: History, Law, Practice and Recent Developments

None
Date: July 5, 2007
Creator: Rosenberg, Morton
Object Type: Report
System: The UNT Digital Library
Medicare Program Changes in H.R. 3962, Affordable Health Care for America Act (open access)

Medicare Program Changes in H.R. 3962, Affordable Health Care for America Act

None
Date: November 5, 2009
Creator: Davis, Patricia A.
Object Type: Report
System: The UNT Digital Library
Federal Register, Volume 74, Number 2, January 5, 2009, Pages 201-392 (open access)

Federal Register, Volume 74, Number 2, January 5, 2009, Pages 201-392

Daily publication of the U.S. Office of the Federal Register contains rules and regulations, proposed legislation and rule changes, and other notices, including "Presidential proclamations and Executive Orders, Federal agency documents having general applicability and legal effect, documents required to be published by act of Congress, and other Federal agency documents of public interest" (p. ii). Table of Contents starts on page iii.
Date: January 5, 2009
Creator: United States. Office of the Federal Register.
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library