Local Effects of Biased Electrodes in the Divertor of NSTX (open access)

Local Effects of Biased Electrodes in the Divertor of NSTX

The goal of this paper is to characterize the effects of small non-axisymmetric divertor plate electrodes on the local scrape-off layer plasma. Four small rectangular electrodes were installed into the outer divertor plates of NSTX. When the electrodes were located near the outer divertor strike point and biased positively, there was an increase in the nearby probe currents and probe potentials and an increase in the LiI light emission at the large major radius end of these electrodes. When an electrode located farther outward from the outer divertor strike point was biased positively, there was sometimes a significant decrease in the LiI light emission at the small major radius end of this electrode, but there were no clear effects on the nearby probes. No non-local effects were observed with the biasing of these electrodes.
Date: May 7, 2012
Creator: : S. Zweben, M.D. Campanell, B.C. Lyons, R.J. Maqueda, Y. Raitses, A.L. Roquemore and F. Scotti
Object Type: Report
System: The UNT Digital Library
Search for Extra Dimensions Using Diphoton Events in 7 TeV Proton-Proton Collisions with the ATLAS Detector (open access)

Search for Extra Dimensions Using Diphoton Events in 7 TeV Proton-Proton Collisions with the ATLAS Detector

None
Date: May 7, 2013
Creator: Aad, Georges
Object Type: Article
System: The UNT Digital Library
Early Fermi Gamma-ray Space Telescope Observations of the Quasar 3C454.3 (open access)

Early Fermi Gamma-ray Space Telescope Observations of the Quasar 3C454.3

This is the first report of Fermi Gamma-ray Space Telescope observations of the quasar 3C 454.3, which has been undergoing pronounced long-term outbursts since 2000. The data from the Large Area Telescope (LAT), covering 2008 July 7-October 6, indicate strong, highly variable {gamma}-ray emission with an average flux of {approx} 3 x 10{sup -6} photons cm{sup -2} s{sup -1}, for energies > 100 MeV. The {gamma}-ray flux is variable, with strong, distinct, symmetrically-shaped flares for which the flux increases by a factor of several on a time scale of about three days. This variability indicates a compact emission region, and the requirement that the source is optically thin to pair-production implies relativistic beaming with Doppler factor {delta} > 8, consistent with the values inferred from VLBI observations of superluminal expansion ({delta} {approx} 25). The observed {gamma}-ray spectrum is not consistent with a simple power-law, but instead steepens strongly above {approx} 2 GeV, and is well described by a broken power-law with photon indices of {approx} 2.3 and {approx} 3.5 below and above the break, respectively. This is the first direct observation of a break in the spectrum of a high luminosity blazar above 100 MeV, and it is likely direct …
Date: May 7, 2009
Creator: Abdo, A. A.
Object Type: Article
System: The UNT Digital Library
Raman Spectroscopy Characterization of amorphous carbon coatings for computer hard disks (open access)

Raman Spectroscopy Characterization of amorphous carbon coatings for computer hard disks

Amorphous carbon films are used as protective coatings on magnetic media to protect the magnetic layer from wear and abrasion caused by the read/write head during hard disk drive start-up and operation. A key requirement in increasing the storage capacity and reliability of hard-disk drives is improving the performance of these coatings. This cooperative agreement used optical characterization techniques developed at LBNL to study thin-film hard disk media produced by Seagate Technology, major US hard drive manufacturer. The chief scientific goal was relating quantitatively the results of the optical characterization to the underlying chemical structure of the overcoat. In a collaboration with Seagate, LBNL, and Cambridge University, optical and electron-based characterization were used to evaluate the chemical structure of overcoats. The sp3 fraction of the sputtered amorphous carbon films was measured quantitatively for the first time and related to the optical spectroscopy results. This work and other selected aspects of the research performed under the agreement were presented at technical meetings and published in the open literature. The chief technical goal was designing manufacturing processes for the protective carbon overcoat for use in new generations of Seagate disk drives. To this end, joint research carried out under this agreement enabled …
Date: May 7, 1998
Creator: Ager, Joel W., III
Object Type: Report
System: The UNT Digital Library
Aging and Fracture of Human Cortical Bone and Tooth Dentin (open access)

Aging and Fracture of Human Cortical Bone and Tooth Dentin

Mineralized tissues, such as bone and tooth dentin, serve as structural materials in the human body and, as such, have evolved to resist fracture. In assessing their quantitative fracture resistance or toughness, it is important to distinguish between intrinsic toughening mechanisms which function ahead of the crack tip, such as plasticity in metals, and extrinsic mechanisms which function primarily behind the tip, such as crack bridging in ceramics. Bone and dentin derive their resistance to fracture principally from extrinsic toughening mechanisms which have their origins in the hierarchical microstructure of these mineralized tissues. Experimentally, quantification of these toughening mechanisms requires a crack-growth resistance approach, which can be achieved by measuring the crack-driving force, e.g., the stress intensity, as a function of crack extension ("R-curve approach"). Here this methodology is used to study of the effect of aging on the fracture properties of human cortical bone and human dentin in order to discern the microstructural origins of toughness in these materials.
Date: May 7, 2008
Creator: Ager, Joel; Koester, Kurt J.; Ager, Joel W., III & Ritchie, Robert O.
Object Type: Article
System: The UNT Digital Library
Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM: Spectral Energy Distributions and Variability in a Low State (open access)

Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM: Spectral Energy Distributions and Variability in a Low State

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated …
Date: May 7, 2009
Creator: Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y. et al.
Object Type: Article
System: The UNT Digital Library
Observation of high energy atmospheric neutrinos with antarctic muon and neutrino detector array (open access)

Observation of high energy atmospheric neutrinos with antarctic muon and neutrino detector array

The Antarctic Muon and Neutrino Detector Array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 10{sup 6} times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 x 10{sup 9} cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90 percent of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.
Date: May 7, 2002
Creator: Ahrens, J.; Andres, E.; Bai, X.; Barouch, G.; Barwick, S. W.; Bay, R. C. et al.
Object Type: Article
System: The UNT Digital Library
Plasma-surface interactions in large tandem mirror devices - MFTF-B (open access)

Plasma-surface interactions in large tandem mirror devices - MFTF-B

Present experiments on TMX-U and modeling of MFTF-B indicate that plasma-surface interactions can be controlled in MFTF-B. The MFTF-B configuration uses a hot electron population created by ECRH and a sloshing-ion population created by neutral beams in the thermal barrier region to create a potential that confines the central cell ions. Neutral beams and ICRH are used to heat the central cell ions. Plasma-surface interactions can be minimized at radial surfaces by control of the axial confinement of the edge plasma. The thermal barrier configuration is sensitive to the background neutral density, and requires low wall reflux and efficient shielding by the edge plasma. Glow discharge cleaning, titanium gettering, and control of the gas from neutral beams will be used to provide wall conditioning and to reduce the background gas pressure. The shielding efficiency of the plasma edge has been modeled in MFTF-B by comparing computer codes with current experimental measurements. In addition, it is very important to reduce high-energy neutral-beam-injected impurities; this is accomplished by using gettering or magnetic separation in the injector systems. Plasma-edge scrapers, diverter-like devices, and direct-conversion equipment will be located in the end region. Major disruptions are not anticipated. Finally, MFTF-B will also test some …
Date: May 7, 1984
Creator: Allen, S.L.
Object Type: Article
System: The UNT Digital Library
Women in the United States Congress: 1917-2008 (open access)

Women in the United States Congress: 1917-2008

This report identifies the names, committee assignments, dates of service, and (for Representatives) districts of the 245 women who have served in Congress.
Date: May 7, 2008
Creator: Amer, Mildred L.
Object Type: Report
System: The UNT Digital Library
Animal Baiting and Fighting: Federal and State Statutes (open access)

Animal Baiting and Fighting: Federal and State Statutes

This report details the federal and state laws regarding animal baiting and fighting. In general, this report found three types of state statutes on this matter: specific legal prohibition aimed at stamping out a practice considered either distasteful, immoral, or a nuisance; general animal cruelty provisions enacted into law which may or may not be held applicable to baiting and fighting or any or all animals, and which may be not be enforced against those involved in such activities; and the absence of statutory restraints due either to open acceptance of animal baiting and fighting as a harmless activity or due to lack of concern over the matter.
Date: May 7, 1976
Creator: American Law Division
Object Type: Report
System: The UNT Digital Library
EFFECTS OF MINERALOGY AND CATION-EXCHANGE CAPACITY ON LIGHIUM SORPTION TO YUCCA MOUNTAIN TUFFS. (open access)

EFFECTS OF MINERALOGY AND CATION-EXCHANGE CAPACITY ON LIGHIUM SORPTION TO YUCCA MOUNTAIN TUFFS.

None
Date: May 7, 1998
Creator: Anghel, I.; Turnin, H. J.; Reimus, P. W. & Carey, J. W.
Object Type: Report
System: The UNT Digital Library
The Individuals with Disabilities Education Act (IDEA): Selected Changes that Would be Made to the Law by S. 1248, 108th Congress (open access)

The Individuals with Disabilities Education Act (IDEA): Selected Changes that Would be Made to the Law by S. 1248, 108th Congress

CRS Report for Congress entailing information about changes being made to the law because of the Individuals with Disabilities Act (IDEA). Topics include, eligibility by jurisdiction, safeguarding, evaluation and Individualized Education Programs (IEPS), etc..
Date: May 7, 2004
Creator: Apling, Richard N. & Jones, Nancy Lee
Object Type: Report
System: The UNT Digital Library
Materials Testing Reactor Project Handbook (open access)

Materials Testing Reactor Project Handbook

The following handbook was made for the purpose of: (1) to give a semidetailed description of the testing reactor, and (2) to explain, in so far as possible, the reasons for the design.
Date: May 7, 1951
Creator: Argonne National Laboratory
Object Type: Report
System: The UNT Digital Library
Hay-Press (open access)

Hay-Press

Patent for a press for hay, straw, and similar. This device, intended for horse-powered bailing processes, is designed for cheap and efficient hay press for the bailing process.
Date: May 7, 1901
Creator: Armstrong, James McRae
Object Type: Patent
System: The Portal to Texas History
Measurements of crystal growth kinetics at extreme deviations from equilibrium. Technical progress report, 1 September 1992--31 August 1993 (open access)

Measurements of crystal growth kinetics at extreme deviations from equilibrium. Technical progress report, 1 September 1992--31 August 1993

We have measured solute trapping of Sn in Al over a wide enough range of velocities to make a quantitative test of theory. The Continuous Growth Model of Aziz is the only one-parameter model that fits the data. We have also measured the diffusive speed - the growth rate at which interfacial partitioning is in mid-transition between equilibrium partitioning and complete solute trapping - for several solutes in A1. We have found an inverse correlation between the equilibrium partition coefficient and the diffusive speed. Taken together, these results give us heretofore unprecedented predictive capability in modeling rapid solidification processing. We have also examined theoretically short-range diffusion-limited growth, characteristic of incomplete solute trapping, and interface-limited growth, characteristic of complete solute trapping, in alloy solidification and have shown that the two regimes fall naturally out of a single unified theory of solidification.
Date: May 7, 1993
Creator: Aziz, M. J.
Object Type: Report
System: The UNT Digital Library
Measurements of crystal growth kinetics at extreme deviations from equilibrium. [Rapid solidification processing] (open access)

Measurements of crystal growth kinetics at extreme deviations from equilibrium. [Rapid solidification processing]

We have measured solute trapping of Sn in Al over a wide enough range of velocities to make a quantitative test of theory. The Continuous Growth Model of Aziz is the only one-parameter model that fits the data. We have also measured the diffusive speed - the growth rate at which interfacial partitioning is in mid-transition between equilibrium partitioning and complete solute trapping - for several solutes in A1. We have found an inverse correlation between the equilibrium partition coefficient and the diffusive speed. Taken together, these results give us heretofore unprecedented predictive capability in modeling rapid solidification processing. We have also examined theoretically short-range diffusion-limited growth, characteristic of incomplete solute trapping, and interface-limited growth, characteristic of complete solute trapping, in alloy solidification and have shown that the two regimes fall naturally out of a single unified theory of solidification.
Date: May 7, 1993
Creator: Aziz, Michael J.
Object Type: Report
System: The UNT Digital Library
Pthreads vs MPI Parallel Performance of Angular-Domain Decomposed S (open access)

Pthreads vs MPI Parallel Performance of Angular-Domain Decomposed S

Two programming models for parallelizing the Angular Domain Decomposition (ADD) of the discrete ordinates (S{sub n}) approximation of the neutron transport equation are examined. These are the shared memory model based on the POSIX threads (Pthreads) standard, and the message passing model based on the Message Passing Interface (MPI) standard. These standard libraries are available on most multiprocessor platforms thus making the resulting parallel codes widely portable. The question is: on a fixed platform, and for a particular code solving a given test problem, which of the two programming models delivers better parallel performance? Such comparison is possible on Symmetric Multi-Processors (SMP) architectures in which several CPUs physically share a common memory, and in addition are capable of emulating message passing functionality. Implementation of the two-dimensional,(S{sub n}), Arbitrarily High Order Transport (AHOT) code for solving neutron transport problems using these two parallelization models is described. Measured parallel performance of each model on the COMPAQ AlphaServer 8400 and the SGI Origin 2000 platforms is described, and comparison of the observed speedup for the two programming models is reported. For the case presented in this paper it appears that the MPI implementation scales better than the Pthreads implementation on both platforms.
Date: May 7, 2000
Creator: Azmy, Y. Y. & Barnett, D. A.
Object Type: Article
System: The UNT Digital Library
Doll. (open access)

Doll.

Patent for a doll that will be durable and attractive by constructing a rigid form of the human bust and shoulders which serves to make these parts more durable, including illustrations and instructions.
Date: May 7, 1912
Creator: Baker, Marie K.
Object Type: Patent
System: The Portal to Texas History
Dense ceramic membranes for hydrogen separation. (open access)

Dense ceramic membranes for hydrogen separation.

We have developed cermet membranes that nongalvanically separate hydrogen from gas mixtures. The highest measured hydrogen flux was 20.0 cm{sup 3} (STP)/min-cm{sup 2} for an ANL-3a membrane at 900 C. For ANL-3 membranes with thickness of 40-500 {micro}m, hydrogen permeation is limited by the bulk diffusion of hydrogen through the metal phase. The effect of hydrogen partial pressure on permeation rate confirmed this conclusion, suggesting that higher permeation rates may be obtained by decreasing the membrane thickness. Permeation rate in a syngas atmosphere for times up to 190 h showed no degradation in performance, which indicates that ANL-3 membranes may be suitable for long-term, practical hydrogen separation.
Date: May 7, 2002
Creator: Balachandran, U.; Lee, T. H.; Wang, S.; Zhang, G. & Dorris, S. E.
Object Type: Article
System: The UNT Digital Library
Energy Policy: Setting the Stage for the Current Debate (open access)

Energy Policy: Setting the Stage for the Current Debate

The Bush Administration issued its plan for a national energy policy on May 16, 2001. The plan was controversial, characterized by some as leaner on conservation and renewables than Democratic proposals, and predisposed to trade off environmental considerations to increase supply. Comprehensive energy legislation was introduced in the Senate by both parties by late March (S. 388, S. 389, S. 596, S. 597). Bills reported by several House committees (H.R. 2436, H.R. 2460, H.R. 2511, and H.R. 2587) were combined in a single bill, H.R. 4, passed by the House, August 1, 2001. The House version of H.R. 4 would require a 5 billion gallon reduction in light-duty truck and SUV fuel consumption and would open the Arctic National Wildlife Refuge (ANWR) to leasing.
Date: May 7, 2002
Creator: Bamberger, Robert L.
Object Type: Report
System: The UNT Digital Library
Apparatus for Solidifying Cotton-Batting Preparatory for Pressing and Baling (open access)

Apparatus for Solidifying Cotton-Batting Preparatory for Pressing and Baling

Patent for an apparatus for forming cotton batting into dense rolls to prepare them for bailing and pressing. Illustrations included.
Date: May 7, 1912
Creator: Banister, Charles
Object Type: Patent
System: The Portal to Texas History
Molecular Environmental Science and Synchrotron Radiation Facilities An Update of the 1995 DOE-Airlie Report on Molecular Environmental Science (open access)

Molecular Environmental Science and Synchrotron Radiation Facilities An Update of the 1995 DOE-Airlie Report on Molecular Environmental Science

This workshop was requested by Dr. Robert Marianelli, Director of the DOE-BES Chemical Sciences Division, to update the findings of the Workshop on Molecular Environmental Sciences (MES) held at Airlie, VA, in July 1995. The Airlie Workshop Report defined the new interdisciplinary field referred to as Molecular Environmental Science (MES), reviewed the synchrotron radiation methods used in MES research, assessed the adequacy of synchrotron radiation facilities for research in this field, and summarized the beam time requirements of MES users based on a national MES user survey. The objectives of MES research are to provide information on the chemical and physical forms (speciation), spatial distribution, and reactivity of contaminants in natural materials and man-made waste forms, and to develop a fundamental understanding of the complex molecular-scale environmental processes, both chemical and biological, that affect the stability, transformations, mobility, and toxicity of contaminant species. These objectives require parallel studies of ''real'' environmental samples, which are complicated multi-phase mixtures with chemical and physical heterogeneities, and of simplified model systems in which variables can be controlled and fundamental processes can be examined. Only by this combination of approaches can a basic understanding of environmental processes at the molecular-scale be achieved.
Date: May 7, 1999
Creator: Bargar, John R
Object Type: Report
System: The UNT Digital Library
Vacuum System of the High Energy Ring of an Asymmetric B-Factory Based on Pep (open access)

Vacuum System of the High Energy Ring of an Asymmetric B-Factory Based on Pep

The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs.
Date: May 7, 1991
Creator: Barletta, W. A.; Calderon, M. O.; Wong, R. & Jenkins, T. M.
Object Type: Article
System: The UNT Digital Library
Neutron source strength monitors for ITER (open access)

Neutron source strength monitors for ITER

There are several goals for the neutron source strength monitor system for the International Thermonuclear Experimental Reactor (ITER). Desired is a stable, reliable, time-dependent neutron detection system which exhibits a wide dynamic range and broad energy response to incident neutrons while being insensitive to gamma rays and having low noise characteristics in a harsh reactor environment. This system should be able to absolutely calibrated in-situ using various neutron sources. An array of proportional counters of varying sensitivities is proposed along with the most promising possible locations. One proposed location is in the pre-shields of the neutron camera collimators which would allow an integrated design of neutron systems with good detector access. As part of an ongoing conceptual design for this system, the detector-specific issues of dynamic range, performance monitoring, and sensitivity will be presented. The location options of the array will be discussed and most importantly, the calibration issues associated with a heavily shielded vessel will be presented.
Date: May 7, 1996
Creator: Barnes, C.W. & Roquemore, A.L.
Object Type: Article
System: The UNT Digital Library