2,589 Matching Results

Search Results

Results: 1 - 24 next
open access

New experimental capabilities and theoretical insights of high pressure compression waves

Description: Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition … more
Date: July 20, 2007
Creator: Orlikowski, D.; Nguyen, J.; Patterson, J. R.; Minich, R.; Martin, L. P. & Holmes, N.
Partner: UNT Libraries Government Documents Department
open access

Loss Factor of the PEP-II Rings

Description: An RF power balance method is used to measure the synchrotron radiation losses and the wake field losses. We present the history of the losses in the Low Energy Ring (LER) and the High Energy Ring (HER) during the last several runs of PEP-II.
Date: July 11, 2008
Creator: Novokhatski, A. & Sullivan, M.
Partner: UNT Libraries Government Documents Department
open access

Elastic electron scattering from formic acid

Description: Following our earlier study on the dynamics of low energy electron attachment to formic acid, we report the results of elastic low-energy electron collisions with formic acid. Momentum transfer and angular differential cross sections were obtained by performing fixed-nuclei calculations employing the complex Kohn variational method. We make a brief description of the technique used to account for the polar nature of this polyatomic target and compare our results with available experimental data. more
Date: July 31, 2006
Creator: Trevisan, Cynthia S.; Orel, Ann E. & Rescigno, Thomas N.
Partner: UNT Libraries Government Documents Department
open access

Certifying Industrial Energy Efficiency Performance: AligningManagement, Measurement, and Practice to Create Market Value

Description: More than fifteen years after the launch of programs in theU.K. and U.S., industry still offers one of the largest opportunities forenergy savings worldwide. The International Energy Agency (IEA) estimatesthe savings potential from cost-optimization of industrial motor-drivensystems alone at 7 percent of global electricity use. The U.S. Departmentof Energy (USDOE) Industrial Technologies Program estimates 7 percentsavings potential in total US industrial energy use through theapplication of pro… more
Date: July 1, 2007
Creator: McKane, Aimee; Scheihing, Paul & Williams, Robert
Partner: UNT Libraries Government Documents Department
open access

First Principles Study of Double Photoionization of H2 UsingExterior Complex Scaling

Description: Exterior complex scaling provides a practical path forfirst-principles studies of atomic and molecular ionizationproblemssince it avoids explicit enforcement of asymptotic boundary conditionsfor 3-body Coulomb breakup. We have used the method of exterior complexscaling, implemented with both the discrete variable representation andB-splines, to obtain the first-order wave function for molecular hydrogencorresponding to a single photon having been absorbed by a correlatedinitial state. These wav… more
Date: July 21, 2006
Creator: Rescigno, Thomas N.; Vanroose, Wim; Horner, Daniel A.; Martin,Fernando & McCurdy, C. William
Partner: UNT Libraries Government Documents Department
open access

Quench performance of Nb3Sn cos-theta coils made of 108/127 RRP strands

Description: A series of 1-m long Nb{sub 3}Sn dipole models has been built at Fermilab in an attempt to refine the wind-and-react technology for Nb3Sn accelerator magnets. Three models made with Powder-in-Tube Nb{sub 3}Sn strand reached their design field of 10 T demonstrating a good reproducibility of magnet quench performance and field quality. Recently a new dipole 'mirror' model based on Nb{sub 3}Sn coil made of improved Restack Rod Process strand was constructed and tested reaching the maximum field ab… more
Date: July 1, 2007
Creator: Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R. et al.
Partner: UNT Libraries Government Documents Department
open access

Radio-loud high-redshift protogalaxy canidates in Bootes

Description: We used the Near Infrared Camera (NIRC) on Keck I to obtain K{sub s}-band images of four candidate high-redshift radio galaxies selected using optical and radio data in the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux densities greater than 1 mJy, but are undetected in the optical. Spectral energy distribution fitting suggests that three of these objects are at z > 3, with radio luminosities near the FR-I/FR-II break. The other has photometric redshift z{sub pho… more
Date: July 20, 2007
Creator: Croft, S.; van Breugel, W.; Brown, M. J.; de Vries, W.; Dey, A.; Eisenhardt, P. et al.
Partner: UNT Libraries Government Documents Department
open access

A fast contour descriptor algorithm for supernova imageclassification

Description: We describe a fast contour descriptor algorithm and its application to a distributed supernova detection system (the Nearby Supernova Factory) that processes 600,000 candidate objects in 80 GB of image data per night. Our shape-detection algorithm reduced the number of false positives generated by the supernova search pipeline by 41% while producing no measurable impact on running time. Fourier descriptors are an established method of numerically describing the shapes of object contours, but tr… more
Date: July 16, 2006
Creator: Aragon, Cecilia R. & Aragon, David Bradburn
Partner: UNT Libraries Government Documents Department
open access

Mg-induced increase of bandgap in Zn1-xMgxO nanorods revealed by x-ray absorption and emission spectroscopy

Description: X-ray absorption near-edge structure (XANES) and x-ray emission spectroscopy (XES) measurements were used to investigate the effect of Mg doping in ZnO nanorods. The intensities of the features in the O K-edge XANES spectra of Zn{sub 1-x}Mg{sub x}O nanorods are lower than those of pure ZnO nanorods, suggesting that Mg doping increases the negative effective charge of O ions. XES and XANES spectra of O 2p states indicate that Mg doping raises (lowers) the conduction-band-minimum (valence-band-ma… more
Date: July 10, 2008
Creator: Pong, Way-Faung; Chiou, J. W.; Tsai, H. M.; Pao, C. W.; Chien, F. Z.; Pong, W. F. et al.
Partner: UNT Libraries Government Documents Department
open access

Multiple Valley Couplings in Nanometer Si MOSFETs

Description: We investigate the couplings between different energy band valleys in a MOSFET device using self-consistent calculations of million-atom Schroedinger-Poisson Equations. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. The MOSFET device is under nonequilibrium condition with a source-drain bias up to 2V, and a gate potential close to the threshold potential. We find that all the intervalley couplings are small, with the coup… more
Date: July 11, 2008
Creator: Wang, Lin-Wang; Deng, Hui-Xiong; Jiang, Xiang-Wei; Luo, Jun-Wei; Li, Shu-Shen; Xia, Jian-Bai et al.
Partner: UNT Libraries Government Documents Department
open access

Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds.

Description: Recent in situ observations in stratiform clouds suggest that mixed phase regimes, here defined as limited cloud volumes containing both liquid and solid water, are constrained to narrow layers (order 100 m) separating all-liquid and fully glaciated volumes (Hallett and Viddaurre, 2005). The Department of Energy Atmospheric Radiation Measurement Program's (DOE-ARM, Ackerman and Stokes, 2003) North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) recently started collecting routine mea… more
Date: July 10, 2006
Creator: Rambukkange,M.; Verlinde, J.; Elorante, E.; Luke, E.; Kollias, P. & Shupe, M.
Partner: UNT Libraries Government Documents Department
open access

Pathway confirmation and flux analysis of central metabolicpathways in Desulfovibrio vulgaris Hildenborough using gaschromatography-mass spectrometry and fourier transform-ion cyclotronresonance mass spectrometry

Description: It has been proposed that during growth under anaerobic oroxygen-limited conditions Shewanella oneidensis MR-1 uses theserine-isocitrate lyase pathway common to many methylotrophic anaerobes,in which formaldehyde produced from pyruvate is condensed with glycine toform serine. The serine is then transformed through hydroxypyruvate andglycerate to enter central metabolism at phosphoglycerate. To examine itsuse of the serine-isocitrate lyase pathway under anaerobic conditions, wegrew S. oneidensis… more
Date: July 11, 2006
Creator: Tang, Yinjie; Pingitore, Francesco; Mukhopadhyay, Aindrila; Phan,Richard; Hazen, Terry C. & Keasling, Jay D.
Partner: UNT Libraries Government Documents Department
open access

MODEL-BASED HYDROACOUSTIC BLOCKAGE ASSESSMENT AND DEVELOPMENT OF AN EXPLOSIVE SOURCE DATABASE

Description: We are continuing the development of the Hydroacoustic Blockage Assessment Tool (HABAT) which is designed for use by analysts to predict which hydroacoustic monitoring stations can be used in discrimination analysis for any particular event. The research involves two approaches (1) model-based assessment of blockage, and (2) ground-truth data-based assessment of blockage. The tool presents the analyst with a map of the world, and plots raypath blockages from stations to sources. The analyst inp… more
Date: July 11, 2005
Creator: Matzel, E; Ramirez, A & Harben, P
Partner: UNT Libraries Government Documents Department
open access

Linearly Scaling 3D Fragment Method for Large-Scale Electronic Structure Calculations

Description: We present a new linearly scaling three-dimensional fragment (LS3DF) method for large scale ab initio electronic structure calculations. LS3DF is based on a divide-and-conquer approach, which incorporates a novel patching scheme that effectively cancels out the artificial boundary effects due to the subdivision of the system. As a consequence, the LS3DF program yields essentially the same results as direct density functional theory (DFT) calculations. The fragments of the LS3DF algorithm can be… more
Date: July 1, 2008
Creator: Wang, Lin-Wang; Lee, Byounghak; Shan, Hongzhang; Zhao, Zhengji; Meza, Juan; Strohmaier, Erich et al.
Partner: UNT Libraries Government Documents Department
open access

Light-Front Holography and Hadronization at the Amplitude Level

Description: The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a rela… more
Date: July 25, 2008
Creator: Brodsky, Stanley J.; de Teramond, Guy & Shrock, Robert
Partner: UNT Libraries Government Documents Department
open access

Multizone Age-of-Air Analysis

Description: Age of air is a technique for evaluating ventilation that has been actively used for over 20 years. Age of air quantifies the time it takes for outdoor air to reach a particular location or zone within then indoor environment. Age of air is often also used to quantify the ventilation effectiveness with respect to indoor air quality. In a purely single zone situation this use of age of air is straightforward, but application of age of air techniques in the general multizone environment has not b… more
Date: July 1, 2007
Creator: Sherman, Max H.
Partner: UNT Libraries Government Documents Department
open access

Entropy of near-extremal black holes in AdS5

Description: We construct the microstates of near-extremal black holes in AdS_5 x S5 as gases of defects distributed in heavy BPS operators in the dual SU(N) Yang-Mills theory. These defects describe open strings on spherical D3-branes in the S5, and we show that they dominate the entropy by directly enumerating them and comparing the results with a partition sum calculation. We display new decoupling limits in which the field theory of the lightest open strings on the D-branes becomes dual to a near-horizo… more
Date: July 24, 2007
Creator: Simon, Joan; Balasubramanian, Vijay; de Boer, Jan; Jejjala, Vishnu & Simon, Joan
Partner: UNT Libraries Government Documents Department
open access

Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

Description: Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile D… more
Date: July 24, 2007
Creator: Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min et al.
Partner: UNT Libraries Government Documents Department
open access

Rh(I)-Catalyzed Direct Arylation of Pyridines and Quinolines

Description: The pyridine and quinoline nuclei are privileged scaffolds that occupy a central role in many medicinally relevant compounds. Consequently, methods for their expeditious functionalization are of immediate interest. However, despite the immense importance of transition-metal catalyzed cross-coupling for the functionalization of aromatic scaffolds, general solutions for coupling 2-pyridyl organometallics with aryl halides have only recently been presented. Direct arylation at the ortho position o… more
Date: July 29, 2008
Creator: Berman, Ashley; Lewis, Jared; Bergman, Robert & Ellman, Jonathan
Partner: UNT Libraries Government Documents Department
Back to Top of Screen