Effects of Global Boundary and Local Collisionality on Magnetic Reconnection in a Laboratory Plasma (open access)

Effects of Global Boundary and Local Collisionality on Magnetic Reconnection in a Laboratory Plasma

The magnetic reconnection process is studied in a wide range of operating conditions in the well-controlled Magnetic Reconnection Experiment. The reconnection rate is observed to be a function of both global (i.e., system size) and local (collisionality) plasma parameters. When only local collisionality is lowered, the current sheet is shortened while effective resistivity is enhanced, both accelerating reconnection rates. At a fixed collisionality, the current sheet length increases with system size, resulting in the reduction of the reconnection rate. These results quantitatively agree with a generalized Sweet-Parker analysis.
Date: July 24, 2007
Creator: A. Kuritsyn, H. Ji, S.P. Gerhardt, Y. Ren, and M. Yamada
Object Type: Report
System: The UNT Digital Library
Micro-Grooving and Micro-Threading Tools for Fabricating Curvilinear Features (open access)

Micro-Grooving and Micro-Threading Tools for Fabricating Curvilinear Features

This paper presents techniques for fabricating microscopic, curvilinear features in a variety of workpiece materials. Micro-grooving and micro-threading tools having cutting widths as small as 13 {micro}m are made by focused ion beam sputtering and used for ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide to create a number of critically aligned facets. Sputtering produces rake facets of desired angle and cutting edges having radii of curvature equal to 0.4 {micro}m. Clearance for minimizing frictional drag of a tool results from a particular ion beam/target geometry that accounts for the sputter yield dependence on incidence angle. It is believed that geometrically specific cutting tools of this dimension have not been made previously. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close match between tool width and feature size. Microtools are used to machine 13 {micro}m wide, 4 {micro}m deep, helical grooves in polymethyl methacrylate and 6061 Al cylindrical workplaces. Micro-grooving tools are also used to fabricate sinusoidal cross-section features in planar metal samples.
Date: July 24, 2000
Creator: Adams, David P.; Vasile, Michael J. & Krishnan, A. S. M.
Object Type: Article
System: The UNT Digital Library
Globalization, Worker Insecurity, and Policy Approaches (open access)

Globalization, Worker Insecurity, and Policy Approaches

None
Date: July 24, 2007
Creator: Aheam, Raymond J.
Object Type: Report
System: The UNT Digital Library
Scalable Analysis Techniques for Microprocessor Performance Counter Metrics (open access)

Scalable Analysis Techniques for Microprocessor Performance Counter Metrics

Contemporary microprocessors provide a rich set of integrated performance counters that allow application developers and system architects alike the opportunity to gather important information about workload behaviors. These counters can capture instruction, memory, and operating system behaviors. Current techniques for analyzing data produced from these counters use raw counts, ratios, and visualization techniques to help users make decisions about their application source code. While these techniques are appropriate for analyzing data from one process, they do not scale easily to new levels demanded by contemporary computing systems. Indeed, the amount of data generated by these experiments is on the order of tens of thousands of data points. Furthermore, if users execute multiple experiments, then we add yet another dimension to this already knotty picture. This flood of multidimensional data can swamp efforts to harvest important ideas from these valuable counters. Very simply, this paper addresses these concerns by evaluating several multivariate statistical techniques on these datasets. We find that several techniques, such as statistical clustering, can automatically extract important features from this data. These derived results can, in turn, be feed directly back to an application developer, or used as input to a more comprehensive performance analysis environment, such as …
Date: July 24, 2002
Creator: Ahn, D H & Vetter, J S
Object Type: Article
System: The UNT Digital Library
European Approaches to Homeland Security and Counterterrorism (open access)

European Approaches to Homeland Security and Counterterrorism

This report examines homeland security and counterterrorist measures in six selected European countries: Belgium, France, Germany, Italy, Spain, and the United Kingdom. None of these European countries currently has a single ministry or department equivalent to the U.S. Department of Homeland Security. In most of these countries, responsibility for different aspects of homeland security and counterterrorism is scattered across several ministries or different levels of government.
Date: July 24, 2006
Creator: Archick, Kristin; Ek, Carl; Gallis, Paul E.; Miko, Francis T. & Woehrel, Steven
Object Type: Report
System: The UNT Digital Library
Recent Advances in High-Pressure Equation-of-State Capabilities (open access)

Recent Advances in High-Pressure Equation-of-State Capabilities

For many scientific and programmatic applications, it is necessary to determine the shock compression response of materials to several tens of Mbar. In addition, a complete EOS is often needed in these applications, which requires that shock data be supplemented with other information, such as temperature measurements or by EOS data off the principal Hugoniot. Recent developments in the use of fast pulsed power techniques for EOS studies have been useful in achieving these goals. In particular, the Z accelerator at Sandia National Laboratories, which develops over 20 million amperes of current in 100-200 ns, can be used to produce muM-Mbar shock pressures and to obtain continuous compression data to pressures exceeding 1 Mbar. With this technique, isentropic compression data have been obtained on several materials to pressures of several hundred kbar. The technique has also been used to launch ultra-high velocity flyer plates to a maximum velocity of 14 km/s, which can be used to produce impact pressures of several Mbar in low impedance materials and over 10 Mbar in high impedance materials. The paper will review developments in both of these areas.
Date: July 24, 2000
Creator: Asay, James R.; Hall, Clint A. & Knudson, Marcus D.
Object Type: Article
System: The UNT Digital Library
Condition Monitoring of a Thermally Aged HTPB/IPDI Elastomer by NMR CP Recovery Times (open access)

Condition Monitoring of a Thermally Aged HTPB/IPDI Elastomer by NMR CP Recovery Times

A hydroxy-terminated polybutadiene (HTPB)/isophorone diisocyanate (IPDI) elastomer is commonly used as propellant binder material. The thermal degradation of the binder is believed to be an important parameter governing the performance of the propellant. The aging of these binders can be monitored by mechanical property measurements such as modulus or tensile elongation. These techniques, however, are not easily adapted to binder agents that are dispersed throughout a propellant. In this paper the authors investigated solid state NMR relaxation times as a means to predict the mechanical properties of the binder as a function of aging time. {sup 1}H spin-lattice and spin-spin relaxation times were found to be insensitive to the degree of thermal degradation of the elastomer. Apparently these relaxation times depend on localized motions that are only weakly correlated with mechanical properties. A strong correlation was found between the {sup 13}C cross-polarization (CP) NMR time constant, T{sub cp}, and the tensile elongation at break of the elastomer as a function of aging time. A ramped-amplitude CP experiment was shown to be less sensitive to imperfections in setting critical instrumental parameters for this mobile material.
Date: July 24, 2000
Creator: Assink, Roger A.; Lang, David & Celina, Mathias C.
Object Type: Article
System: The UNT Digital Library
Does Price Transparency Improve Market Efficiency? Implications of Empirical Evidence in Other Markets for the Health Sector (open access)

Does Price Transparency Improve Market Efficiency? Implications of Empirical Evidence in Other Markets for the Health Sector

None
Date: July 24, 2007
Creator: Austin, D. Andrew & Gravelle, Jane G.
Object Type: Report
System: The UNT Digital Library
INTRACELLULAR COPPER ACCUMULATION ENHANCES THE GROWTH OF KINEOCOCCUS RADIOTOLERANS DURING CHRONIC IRRADIATION (open access)

INTRACELLULAR COPPER ACCUMULATION ENHANCES THE GROWTH OF KINEOCOCCUS RADIOTOLERANS DURING CHRONIC IRRADIATION

The actinobacteria Kineococcus radiotolerans is highly resistant to ionizing radiation, desiccation, and oxidative stress; though the underlying biochemical mechanisms are unknown. The purpose of this study was to explore a possible linkage between the uptake of transition metals and extreme resistance to ionizing radiation and oxidative stress. The effects of 6 different divalent cationic metals on growth were examined in the absence of ionizing radiation. None of the metals tested were stimulatory, though cobalt was inhibitory to growth. In contrast, copper supplementation dramatically increased cell growth during chronic irradiation. K. radiotolerans exhibited specific uptake and intracellular accumulation of copper compared to only a weak response to both iron and manganese supplementation. Copper accumulation sensitized cells to hydrogen peroxide. Acute irradiation induced DNA damage was similar between the copper-loaded culture as the age-synchronized no copper control culture, though low molecular weight DNA was more persistent during post-irradiation recovery in the Cu-loaded culture. Still, the estimated times for genome restoration differed by only 1 hr between treatments. While we cannot discount the possibility that copper fulfills an unexpectedly important biochemical role in a radioactive environment; K. radiotolerans has a high capacity for intracellular copper sequestration, and presumably efficiently coordinated oxidative stress defenses …
Date: July 24, 2007
Creator: Bagwell, C & Charles Milliken, C
Object Type: Article
System: The UNT Digital Library
Defense Cleanup and Environmental Programs: Authorization and Appropriations for FY2003 (open access)

Defense Cleanup and Environmental Programs: Authorization and Appropriations for FY2003

The Department of Defense (DOD) administers five environmental programs in response to various requirements under federal environmental laws. These programs include environmental cleanup, environmental compliance, pollution prevention, environmental technology, and conservation. Additionally, the Department of Energy (DOE) is responsible for managing defense nuclear waste and cleaning up contaminated nuclear weapons sites. The Administration requested a total of $11.17 billion for these programs in FY2003, about $390 million more than the FY2002 funding level of $10.78 billion. Some of the ongoing issues associated with these programs are the adequacy, cost, and pace of cleanup, whether DOD and DOE adequately comply with environmental laws and regulations, and the extent to which environmental requirements encroach upon military readiness.
Date: July 24, 2003
Creator: Bearden, David M.
Object Type: Report
System: The UNT Digital Library
Country-of-Origin Labeling for Foods (open access)

Country-of-Origin Labeling for Foods

This report provides information about the Country-of-Origin Labeling for Foods. Federal law requires most imports, including many food items to bear labels informing the "ultimate purchaser" of their country of origin.
Date: July 24, 2007
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
The (178m2)Hf Controversy (open access)

The (178m2)Hf Controversy

Since its discovery in the 1960's the {sup 178m2}Hf isomer has garnered high attention from both the basic and applied communities in nuclear science. It's combination of high spin (16+), long half life (31 yrs), and high excitation energy (2.446 MeV) offer unique possibilities as an energy storage medium. Interest in the isomer was rekindled beginning in 1999 when a series of publications began to appear from a group (referred to here as the ''Texas collaboration'') primarily based at the University of Texas, Dallas [1]. They reported observations that some of the stored energy could be released (''triggered'') when the isomer was exposed to a fluence of photons in the energy range {approx}10 to {approx}60 keV. The implications of this observation are profound. Even though the claimed cross section for the process was {approx}7 orders of magnitude greater than would be predicted from the known systematics of photon absorption by nuclei in this mass range [2], such a highly efficient method for triggering the isomeric deexcitation immediately suggested applications utilizing the explosive or the controlled gradual energy release from a very compact source. The prospect of such applications has focused considerable interest on realizing the promise that is implicit in …
Date: July 24, 2003
Creator: Becker, J. A.; Gemmell, D. S.; Schiffer, J. P. & Wilhelmy, J. B.
Object Type: Report
System: The UNT Digital Library
Intelligence Issues for Congress (open access)

Intelligence Issues for Congress

None
Date: July 24, 2009
Creator: Best, Richard A. Jr.
Object Type: Report
System: The UNT Digital Library
International Population Assistance and Family Planning Programs: Issues for Congress (open access)

International Population Assistance and Family Planning Programs: Issues for Congress

This report discusses the U.S. population assistance issues, policy issues in the U.S. family planning debate, and U.S. funding levels.
Date: July 24, 2008
Creator: Blanchfield, Luisa
Object Type: Report
System: The UNT Digital Library
The U.N. Population Fund: Background and the U.S. Funding Debate (open access)

The U.N. Population Fund: Background and the U.S. Funding Debate

This report provides an overview of the United Nations Population Fund (UNFPA), its current mission and operations, and recent funding trends. It further discusses the role of the United States in supporting the UNFPA programs, the varying interpretations by several Administrations of legislative authorities pertaining to UNFPA's eligibility for American resources, and congressional debates over how much and under what conditions the United States should voluntarily contribute to UNFPA operations. Finally, it reviews the findings of several private and U.S. government investigations of China's family planning programs and the role UNFPA plays in their implementation.
Date: July 24, 2008
Creator: Blanchfield, Luisa
Object Type: Report
System: The UNT Digital Library
Biological Weapons: A Primer (open access)

Biological Weapons: A Primer

Concerns for Biological weapons (BW) are being viewed as a threat and a "when, if not" scenario. What is the nature of biological weapons and the treat assessments. The U.S laws and regulations that adhere to BW weapons.
Date: July 24, 2001
Creator: Bowman, Steve
Object Type: Report
System: The UNT Digital Library
Kosovo: U.S. and Allied Military Operations (open access)

Kosovo: U.S. and Allied Military Operations

None
Date: July 24, 2000
Creator: Bowman, Steven R.
Object Type: Report
System: The UNT Digital Library
Welding Behavior of Free Machining Stainless Steel (open access)

Welding Behavior of Free Machining Stainless Steel

The weld solidification and cracking behavior of sulfur bearing free machining austenitic stainless steel was investigated for both gas-tungsten arc (GTA) and pulsed laser beam weld processes. The GTA weld solidification was consistent with those predicted with existing solidification diagrams and the cracking response was controlled primarily by solidification mode. The solidification behavior of the pulsed laser welds was complex, and often contained regions of primary ferrite and primary austenite solidification, although in all cases the welds were found to be completely austenite at room temperature. Electron backscattered diffraction (EBSD) pattern analysis indicated that the nature of the base metal at the time of solidification plays a primary role in initial solidification. The solid state transformation of austenite to ferrite at the fusion zone boundary, and ferrite to austenite on cooling may both be massive in nature. A range of alloy compositions that exhibited good resistance to solidification cracking and was compatible with both welding processes was identified. The compositional range is bounded by laser weldability at lower Cr{sub eq}/Ni{sub eq} ratios and by the GTA weldability at higher ratios. It was found with both processes that the limiting ratios were somewhat dependent upon sulfur content.
Date: July 24, 2000
Creator: Brooks, John A.; Robino, Charles V.; Headley, Thomas J. & Michael, Joseph R.
Object Type: Article
System: The UNT Digital Library
Final report on the National Conference of State Legislatures project 'Assistance to State Legislatures on Alternative Fuel Vehicle Issues' (open access)

Final report on the National Conference of State Legislatures project 'Assistance to State Legislatures on Alternative Fuel Vehicle Issues'

This report assesses the effectiveness of state alternative fuel vehicle incentives and suggests incentives that might encourage new vehicle technologies. It does not assess whether a state should promote alternative fuel vehicles or whether such vehicles are the most effective means to reduce air pollution.
Date: July 24, 2000
Creator: Brown, Matthew & Sundeen, Matt
Object Type: Report
System: The UNT Digital Library
Microturbulence, Heat, and Particle Fluxes in JET and DIII-D ITB Plasmas with Highly Reversed Magnetic Shear (open access)

Microturbulence, Heat, and Particle Fluxes in JET and DIII-D ITB Plasmas with Highly Reversed Magnetic Shear

Practical tokamak reactors will need to maintain high ion temperature and nD approximately equal to nT in the core for long durations. These conditions will necessitate low energy transport, low impurity concentrations, and high bootstrap current. Large extrapolations from present experiments are needed to predict performance. A number of approaches are being used for these extrapolations including: (1) dimensionless scaling arguments, (2) empirical scaling, and (3) physics-based simulations of anomalous transport.
Date: July 24, 2003
Creator: Budny, R. V.; Andre, R.; Challis, C. D.; Dorland, W.; Dux, R.; Ernst, D. R. et al.
Object Type: Report
System: The UNT Digital Library
Arroyo Mocho Boulder Removal Project: Lawrence Livermore National Laboratory Hetch Hetchy Pump Station (open access)

Arroyo Mocho Boulder Removal Project: Lawrence Livermore National Laboratory Hetch Hetchy Pump Station

None
Date: July 24, 2007
Creator: Burkholder, L; Kato, T & van Hattem, M
Object Type: Report
System: The UNT Digital Library
DEVELOPMENT OF HIGH ACTIVITY, COAL-DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES (open access)

DEVELOPMENT OF HIGH ACTIVITY, COAL-DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES

This project is directed at an investigation of catalytic NO{sub x} reduction mechanisms on coal-derived, activated carbon supports at low temperatures. Promoted carbon systems offer some potentially significant advantages for heterogeneous NO{sub x} reduction. These include: low cost; high activity at low temperatures, which minimizes carbon loss; oxygen resistance; and a support material which can be engineered with respect to porosity, transport and catalyst dispersion characteristics. During the reporting period, TPD studies were conducted following steady-state reaction in NO/CO mixtures in helium. From these studies, the following points have been concluded: (1) The total amount of CO and N{sub 2} evolved following reaction in NO increases with reaction temperature. The TPD spectra are skewed to high temperatures, indicating more stable surface complexes with high desorption activation energies. (2) The total amount of CO evolved following exposure of the char sample to CO at reaction temperatures decreases with reaction temperature, similar to chemisorption behavior. The CO TPD spectra are shifted to lower temperatures, indicating more labile oxygen surface complexes with lower desorption activation energies. (3) The total amount of CO evolved following reaction in NO/CO mixtures decreases with reaction temperature, while the evolved N{sub 2} still increases with reaction temperature. The …
Date: July 24, 2000
Creator: Calo, Joseph M.
Object Type: Report
System: The UNT Digital Library
Defects at the carbon terminated SiC (001) surface (open access)

Defects at the carbon terminated SiC (001) surface

We present first principle molecular dynamics simulations for selected point defects on the (001) stoichiometric carbon terminated surface of cubic Silicon Carbide. In particular we investigated missing units and coordination defects. The results of our calculations are compared with recent experiments, in particular we discuss simulated STM images, which are in good agreement with measured ones.
Date: July 24, 2000
Creator: Catellani, A & Galli, G
Object Type: Article
System: The UNT Digital Library
2007 SB14 Source Reduction Plan/Report (open access)

2007 SB14 Source Reduction Plan/Report

Aqueous solutions (mixed waste) generated from various LLNL operations, such as debris washing, sample preparation and analysis, and equipment maintenance and cleanout, were combined for storage in the B695 tank farm. Prior to combination the individual waste streams had different codes depending on the particular generating process and waste characteristics. The largest streams were CWC 132, 791, 134, 792. Several smaller waste streams were also included. This combined waste stream was treated at LLNL's waste treatment facility using a vacuum filtration and cool vapor evaporation process in preparation for discharge to sanitary sewer. Prior to discharge, the treated waste stream was sampled and the results were reviewed by LLNL's water monitoring specialists. The treated solution was discharged following confirmation that it met the discharge criteria. A major source, accounting for 50% for this waste stream, is metal machining, cutting and grinding operations in the engineering machine shops in B321/B131. An additional 7% was from similar operations in B131 and B132S. This waste stream primarily contains metal cuttings from machined parts, machining coolant and water, with small amounts of tramp oil from the machining and grinding equipment. Several waste reduction measures for the B321 machine shop have been taken, including the …
Date: July 24, 2007
Creator: Chang, L
Object Type: Report
System: The UNT Digital Library