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On the occasion of the inauguration of Balenciaga and His Legacy: Haute Couture from the Texas Fashion Collection (open access)

On the occasion of the inauguration of Balenciaga and His Legacy: Haute Couture from the Texas Fashion Collection

Article and gallery of photographs from the gala premiere for the "Balenciaga and His Legacy: Haute Couture from the Texas Fashion Collection" exhibit held at the Meadows Museum in Dallas.
Date: March 24, 2007
Creator: Adams, Sharon
System: The UNT Digital Library
Measurement of Electron Impact Collisional Excitation Cross Sections of Ni to Ga-Like Gold (open access)

Measurement of Electron Impact Collisional Excitation Cross Sections of Ni to Ga-Like Gold

None
Date: August 24, 2004
Creator: May, M.; Beiersdorfer, P.; Jordan, N.; Scofield, J.; Reed, K.; Hansen, S. et al.
System: The UNT Digital Library
Graph based multilevel algorithms for preconditioning finite element problems (open access)

Graph based multilevel algorithms for preconditioning finite element problems

This paper discusses: (1) A general block-factorization (matrix) form of multilevel preconditioners; algebraic methods; (2) Selecting parameters based on the matrix topology; graph based algorithms; (3) Examples of coarsening; (4) Numerical experiments.
Date: March 24, 2000
Creator: Vassilevski, P S
System: The UNT Digital Library
Physics and Applications of NIS Junctions (open access)

Physics and Applications of NIS Junctions

This paper reviews the physics and applications of Normal-Insulator-Superconductor (NIS) tunnel junctions. The current-voltage properties of NIS junctions are diode-like with a strong temperature dependence. Hence, these structures can be used as sensitive thermometers at temperatures well below the energy gap, {Delta}, of the superconducting electrode. For junction voltages comparable to {Delta}/q, current flow removes energy from the normal electrode. This property has been exploited to build refrigerators capable of cooling thin-film circuits from 0.3 K to 0.1 K. Calorimeters and bolometers for the detection of X-rays and millimeter-wave radiation, respectively, have successfully been built from NIS junctions. NIS junctions have also been used to probe the superconducting state. Finally, recent ideas for the use of NIS junctions as simple circuit elements are described.
Date: August 24, 2001
Creator: Ullom, J N
System: The UNT Digital Library
Ultrasound Imaging Using Diffraction Tomography in a Cylindrical Geometry (open access)

Ultrasound Imaging Using Diffraction Tomography in a Cylindrical Geometry

Tomographic images of tissue phantoms and a sample of breast tissue have been produced from an acoustic synthetic array system for frequencies near 500 kHz. The images for sound speed and attenuation show millimeter resolution and demonstrate the feasibility of obtaining high-resolution tomographic images with frequencies that can deeply penetrate tissue. The image reconstruction method is based on the Born approximation to acoustic scattering and is a simplified version of a method previously used by Andre (Andre, et. al., Int. J. Imaging Systems and Technology, Vol 8, No. 1, 1997) for a circular acoustic array system. The images have comparable resolution to conventional ultrasound images at much higher frequencies (3-5 MHz) but with lower speckle noise. This shows the potential of low frequency, deeply penetrating, ultrasound for high-resolution quantitative imaging.
Date: January 24, 2002
Creator: Chambers, D H & Littrup, P
System: The UNT Digital Library
Experimental investigation of high mach number 3D hydrodynamic jets at the National Ignition Facility (open access)

Experimental investigation of high mach number 3D hydrodynamic jets at the National Ignition Facility

The first hydrodynamics experiments were performed on the National Ignition Facility. A supersonic jet was formed via the interaction of a laser driven shock ({approx}40 Mbars) with 2D and 3D density perturbations. The temporal evolution of the jet's spatial scales and ejected mass were measured with point projection x-ray radiography. Measurements of the large-scale features and mass are in good agreement with 2D and 3D numerical simulations. These experiments are the first quantitative measurements of the evolution of 3D supersonic jets and provide insight into their 3D behavior.
Date: September 24, 2004
Creator: Blue, B. E.; Weber, S.; Glendinning, S.; Lanier, N.; Woods, D.; Bono, M. et al.
System: The UNT Digital Library
Simulation of Plasma Fluxes to Material Surfaces with Self-Consistent Edge Turbulence and Transport for Tokamaks (open access)

Simulation of Plasma Fluxes to Material Surfaces with Self-Consistent Edge Turbulence and Transport for Tokamaks

The edge-plasma profiles and fluxes to the divertor and walls of a divertor tokamak with a magnetic X-point are simulated by coupling a 2D transport code (UEDGE) and a 3D turbulence code (BOUT). An relaxed iterative coupling scheme is used where each code is run on its characteristic time scale, resulting in a statistical steady state. Plasma variables of density, parallel velocity, and separate ion and electron temperatures are included, together with a fluid neutral model for recycling neutrals at material surfaces. Results for the DIII-D tokamak parameters show that the turbulence is preferentially excited in the outer radial region of the edge where magnetic curvature is destabilizing and that substantial plasma particle flux is transported to the main chamber walls. These results are qualitatively consistent with some experimental observations. The coupled transport/turbulence simulation technique provides a strategy to understanding edge-plasma physics in more detailed than previously available and to significantly enhance the realism of predictions of the performance of future devices.
Date: May 24, 2004
Creator: Rognlien, T.; Umansky, M.; Xu, X.; Cohen, R. & LoDestro, L.
System: The UNT Digital Library
Actinic inspection of multilayer defects on EUV masks (open access)

Actinic inspection of multilayer defects on EUV masks

The production of defect-free mask blanks, and the development of techniques for inspecting and qualifying EUV mask blanks, remains a key challenge for EUV lithography. In order to ensure a reliable supply of defect-free mask blanks, it is necessary to develop techniques to reliably and accurately detect defects on un-patterned mask blanks. These inspection tools must be able to accurately detect all critical defects whilst simultaneously having the minimum possible false-positive detection rate. There continues to be improvement in high-speed non-actinic mask blank inspection tools, and it is anticipated that these tools can and will be used by industry to qualify EUV mask blanks. However, the outstanding question remains one of validating that non-actinic inspection techniques are capable of detecting all printable EUV defects. To qualify the performance of non-actinic inspection tools, a unique dual-mode EUV mask inspection system has been installed at the Advanced Light Source (ALS) synchrotron at Lawrence Berkeley National Laboratory. In high-speed inspection mode, whole mask blanks are scanned for defects using 13.5-nm wavelength light to identify and map all locations on the mask that scatter a significant amount of EUV light. In imaging, or defect review mode, a zone plate is placed in the reflected …
Date: March 24, 2005
Creator: Barty, A.; Liu, Y.; Gullikson, E.; Taylor, J. S. & Wood, O.
System: The UNT Digital Library
Electron Cyclotron Heating and Current Drive for Maintaining Minimum q in Negative Central Shear Discharges (open access)

Electron Cyclotron Heating and Current Drive for Maintaining Minimum q in Negative Central Shear Discharges

Toroidal plasmas created with negative magnetic shear in the core region offer advantages in terms of MHD stability properties. These plasmas, transiently created in several tokamaks, have exhibited high performance as measured by normalized stored energy and neutron production rates. A critical issue with extending the duration of these plasmas is the need to maintain the off-axis-peaked current distribution required to support the minimum in the safety factor q at large radii. We present equilibrium and transport simulations that explore the use of electron cyclotron heating and current drive to maintain this negative shear configuration. Using parameters consistent with DIII-D tokamak operation, we find that with sufficiently high injected power, it is possible to achieve steady-state conditions employing well aligned electron cyclotron and bootstrap current drive in fully non-inductively current-driven configurations.
Date: April 24, 2003
Creator: Casper, T. A.; Kaiser, T. B.; Jong, R. A.; LoDestro, L. L.; Moller, J.; Pearlstein, L. D. et al.
System: The UNT Digital Library
Comparison of Plasma Parameters Between QH and ELMing Phases of the Same Discharges (open access)

Comparison of Plasma Parameters Between QH and ELMing Phases of the Same Discharges

H-mode confinement is observed for many energy confinement times without edge localized modes (ELMs) in QH (quiescent high-confinement)-mode discharges in DIII-D. To find critical differences between ELMing and QH modes we compared electron temperature (T{sub e}), density (n{sub e}), and ion temperature (T{sub i}), in the pedestal and scrape-off layer (SOL) for a group of discharges. We also compared the electron pressures P{sub ped}, and maximum pressure gradients P{sub e,ped,max grad} because of their importance in confinement and stability. Experimental results show that the core line averaged density, median T{sub e} (pedestal), SOL T{sub e}, and T{sub e} pedestal width, and SOL T{sub i} are nearly the same in QH mode as that during ELMs. The n{sub e} (average pedestal), n{sub e} pedestal width, P{sub ped}, and P{sub e,ped,max grad} are similar to corresponding values in QH mode and at various times between ELMs. However, the pedestal T{sub i} is 1.6 times higher in QH mode than during ELMing.
Date: May 24, 2004
Creator: Lasnier, C.; West, W.; Burrell, K.; deGrassie, J.; Doyle, E. & Osborne, T.
System: The UNT Digital Library
Determining Cross Sections for Reactions on Unstable Nuclei: A Consideration of Indirect Approaches (open access)

Determining Cross Sections for Reactions on Unstable Nuclei: A Consideration of Indirect Approaches

An indirect method for determining cross sections for reactions proceeding through a compound nucleus is presented. The appropriate theoretical framework for applications of this method is reviewed and theoretical and experimental challenges that need to be addressed in applications of the method are outlined. Two approximations are considered and their advantages and limitations are discussed.
Date: May 24, 2005
Creator: Escher, J & Dietrich, F S
System: The UNT Digital Library
UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS. (open access)

UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS.

The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at {radical}(s{sub NN}) = 19.6, 130 and 200 GeV. Two observations indicate universal behavior of charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/{bar p}p and e{sup +}e{sup -} data. <Nch>/<N{sub part}/2> in nuclear collisions at high energy scales with {radical}s in a similar way as N{sub ch} in e{sup +}e{sup -} collisions and has a very weak centrality dependence. These features may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.
Date: July 24, 2002
Creator: STEINBERG,P. A. FOR THE PHOBOS COLLABORATION
System: The UNT Digital Library
Frequency Conversion Activation on the Mercury Laser (open access)

Frequency Conversion Activation on the Mercury Laser

High efficiency frequency conversion while operating at average power is critical for the Mercury laser. We will demonstrate average power frequency conversion of face-cooled DKDP and YCOB crystals using a sapphire heat spreader approach.
Date: September 24, 2004
Creator: Bayramian, A. J.; Beach, R. J.; Bibeau, C.; Campbell, R.; Ebbers, C. A.; Freitas, B. L. et al.
System: The UNT Digital Library
STELLA-II: DEMONSTRATION OF MONOENERGETIC LASER ACCELERATION. (open access)

STELLA-II: DEMONSTRATION OF MONOENERGETIC LASER ACCELERATION.

Monoenergetic laser acceleration of trapped microbunches has been demonstrated for the first time. An inverse free electron laser (IFEL) is used to create microbunches, which are then accelerated by a second IFEL using a tapered undulatos. An adjustable magnetic field chicane is located between the two IFELs and is used to control the phase of the microbunches with respect to the laser field in the second IFEL. The IFELs are driven by a single lases beam from a high peak power CO{sub 2} laser. During the experiment, the trapped portion of the microbunch electrons had an energy gain of >16% with an energy width of -0.86% (full width at half-maximum).
Date: March 24, 2004
Creator: KIMURA,W. D. BABZIEN,M. BEN-ZVI,I. GALLARDO,J. C. KUSCHE,K. P. POGORELSKY,I. V. SKARITKA,J. YAKIMENKO,V. ET AL.
System: The UNT Digital Library
Review of Practice for Deeply Embedded/Buried Npp Structures Subject to Seismic Loadings. (open access)

Review of Practice for Deeply Embedded/Buried Npp Structures Subject to Seismic Loadings.

Motivated by many design considerations, several conceptual designs for advanced reactors have proposed that the entire reactor building and a significant portion of the steam generator building will be either partially or completely embedded below grade. For the analysis of seismic events, the soil-structure interaction (SSI) effect and passive earth pressure for these types of deeply embedded structures will have a significant influence on the predicted seismic response. Sponsored by the US Nuclear Regulatory Commission (NRC), Brookhaven National Laboratory (BNL) is carrying out a research program to assess the significance of these proposed design features for advanced reactors, and to evaluate the existing analytical methods to determine their applicability and adequacy in capturing the seismic behavior of the proposed designs. This paper summarizes a literature review performed by BNL to determine the state of knowledge and practice for seismic analyses of deeply embedded and/or buried (DEB) nuclear containment type structures. Included in the paper is BNL's review of the open literature of existing standards, tests, and practices that have been used in the design and analysis of DEB structures. The paper also provides BNL's evaluation of available codes and guidelines with respect to seismic design practice of DEB structures. Based …
Date: March 24, 2004
Creator: Xu, J.; Hofmayer, C.; Miller, C. & Graves, H.
System: The UNT Digital Library
Understanding Particle Defect Transport in an Ultra-Clean Sputter Coating Process (open access)

Understanding Particle Defect Transport in an Ultra-Clean Sputter Coating Process

Low-defect mask blanks remain a key technical challenge to Extreme Ultraviolet Lithography (EUVL). The mask blank is ion-beam sputter-coated with an 81-layer Mo/Si multilayer stack for high reflectance at {lambda} = 13.4nm. The current mask coating process can achieve a median added defect level of 0.05 defects/cm{sup 2} (12 added defects 90nm or larger on a 200mm Si-wafer test substrate), but this must be reduced by about a factor of 10 to meet mask cost requirements for EUVL. To further reduce the particle defect level, we have studied pathways for particle transport, using test particles and particles native to the coating process, and combined the results into a computational model of particle transport in an ion-beam sputter system. At process pressure, gas drag is negligible for particles above 100nm, so particles travel ballistically until they hit a surface. Bounce from chamber walls allows particles to reach all surfaces in the chamber if they have initial velocities above {approx}100m/s. The ion beam has sufficient momentum to entrain slower particles and accelerate them toward the sputter target, where some can bounce to the substrate. The model shows preliminary agreement with experimental defect distributions on witness wafers at various positions within the coating …
Date: March 24, 2003
Creator: Walton, C.; Kearney, P.; Folta, J.; Sweeney, D. & Mirkarimi, P.
System: The UNT Digital Library
Design and Testing of a Fast, 50 kV Solid-State Kicker Pulser (open access)

Design and Testing of a Fast, 50 kV Solid-State Kicker Pulser

The ability to extract particle beam bunches from a ring accelerator in arbitrary order can greatly extend an accelerator's capabilities and applications. A prototype solid-state kicker pulser capable of generating asynchronous bursts of 50 kV pulses has been designed and tested into a 50{Omega} load. The pulser features fast rise and fall times and is capable of generating an arbitrary pattern of pulses with a maximum burst frequency exceeding 5 MHz If required, the pulse-width of each pulse in the burst is independently adjustable. This kicker modulator uses multiple solid-state modules stacked in an inductive-adder configuration where the energy is switched into each section of the adder by a parallel array of MOSFETs. Test data, capabilities, and limitations of the prototype pulser are described.
Date: June 24, 2002
Creator: Cook, E. G.; Hickman, B. C.; Lee, B. S.; Hawkins, S. A.; Gower, E. J.; Allen, F. V. et al.
System: The UNT Digital Library
Out-of-core Interactive Display of Large Meshes Using an Oriented Bounding Box-based Hardware Depth Query (open access)

Out-of-core Interactive Display of Large Meshes Using an Oriented Bounding Box-based Hardware Depth Query

In this paper we present an occlusion culling method that uses hardware-based depth queries on oriented bounding boxes to cull unseen geometric primitives efficiently. An out-of-core design enables this method to interactively display data sets that are too large to fit into main memory. During a preprocessing phase, a spatial subdivision (such as an octree or BSP tree) of a given data set is constructed where, for each node, an oriented bounding box containing mesh primitives is computed using principal component analysis (PCA). At runtime, the tree indicated by the spatial subdivision is traversed in front-to-back order, and only nodes that are determined to be visible, based on a hardware accelerated depth query, are rendered.
Date: June 24, 2004
Creator: Ha, H; Gregorski, B & Joy, K I
System: The UNT Digital Library
Structure of pyrR (Rv1379) from Mycobacterium tuberculosis: A persistence gene and protein drug target (open access)

Structure of pyrR (Rv1379) from Mycobacterium tuberculosis: A persistence gene and protein drug target

The 1.9 {angstrom} native structure of pyrimidine biosynthesis regulatory protein encoded by the Mycobacterium tuberculosis pyrR gene (Rv1379) is reported. Because pyrimidine biosynthesis is an essential step in the progression of TB, pyrR is an attractive antitubercular drug target. The Mycobacterium tuberculosis pyrR gene (Rv1379) encodes a protein that regulates expression of pyrimidine nucleotide biosynthesis (pyr) genes in a UMP-dependent manner. Because pyrimidine biosynthesis is an essential step in the progression of TB, the gene product pyrR is an attractive antitubercular drug target. We report the 1.9 {angstrom} native structure of Mtb pyrR determined by the TB Structural Genomics Consortium facilities (PDB entry 1W30) in trigonal space group P3{sub 1}21, with cell dimensions at 120K of a = 66.64 {angstrom}, c = 154.72 {angstrom}, and two molecules in the asymmetric unit. The 3D structure and residual uracil phosphoribosyltransferase activity point to a common PRTase ancestor for pyrR. However, while PRPP and UMP binding sites have been retained in Mtb pyrR, a novel dimer interaction among subunits creates a deep, positively charged cleft capable of binding pyr mRNA. In silico screening of pyrimidine nucleoside analogs has revealed a number of potential leads compounds that, if bound to Mtb pyrR, could facilitate …
Date: September 24, 2004
Creator: Kantardjieff, K A; Vasquez, C; Castro, P; Warfel, N M; Rho, B; Lekin, T et al.
System: The UNT Digital Library
Applications of Crystal Plasticity in Multiscale Modeling (open access)

Applications of Crystal Plasticity in Multiscale Modeling

Multiscale modeling with crystal plasticity constitutive relations is used to determine the average response of a polycrystal. The measured crystallographic texture of a copper shaped charge liner is used in a crystal plasticity model to construct a yield surface that exhibits normal-shear coupling. Simulations with this yield surface model demonstrate the spinning behavior observed in the spin formed copper shaped charges.
Date: September 24, 2001
Creator: Becker, R.; Busche, M.; Schwartz, A. J. & Kumar, M.
System: The UNT Digital Library
Review of cathodic arc deposition technology at the start of the new millennium (open access)

Review of cathodic arc deposition technology at the start of the new millennium

The vacuum cathodic arc has been known to provide a means of producing coatings since the second half of the 19th century. This makes it one of the oldest known means for making coatings in a vacuum. In the last century it has been recognized that the copious quantities of ions produced by the process offers certain advantages in terms of coating properties. Specifically, ions can be steered and/or accelerated toward the parts to be coated. This, in turn, can provide enhanced adhesion, film density, and composition stoichiometry in the case of compound coatings. The ions generated by the cathodic arc have high ''natural'' kinetic energy values in the range 20-200 eV, leading to enhanced surface mobility during the deposition process and even ion subplantation. In many cases, dense coatings are achieved even when non-normal arrival angles are involved. The ion energy can further manipulated by the plasma immersion biasing technique. The issue of macroparticle contamination has been addressed by a variety of novel plasma filters. In spite of all of these advantages, this deposition technique has not been widely adopted in the western nations for commercial coating except in the case of enhancing the performance of cutting tools. The …
Date: February 24, 2000
Creator: Sanders, D. M. & Anders, A.
System: The UNT Digital Library
US NEUTRINO FACTORY STUDIES. (open access)

US NEUTRINO FACTORY STUDIES.

The design and simulated performance of a second feasibility study are presented. The efficiency of producing muons is {approx} 0.17 {micro}/p with 24 GeV protons. This study was sponsored by the BNL Director, with BNL site specific driver and layout. It was a follow on to the First Study sponsored by the Fermilab Director, with Fermilab site specific driver and layout, and was the main US collaboration conceptual effort during the past year. Other studies, and technical work by the collaboration is reported in other papers.
Date: May 24, 2001
Creator: OZAKI,S. PALMER,R. B. ZISMAN,M. S.
System: The UNT Digital Library
Predicting and Evaluating the Effectiveness of Ocean Carbon Sequestration by Direct Injection (open access)

Predicting and Evaluating the Effectiveness of Ocean Carbon Sequestration by Direct Injection

Direct injection of CO{sub 2} into the ocean is a potentially effective carbon sequestration strategy. Therefore, we want to understand the effectiveness of oceanic injection and develop the appropriate analytic framework to allow us to compare the effectiveness of this strategy with other carbon management options. Here, after a brief review of direct oceanic injection, we estimate the effectiveness of ocean carbon sequestration using one dimensional and three dimensional ocean models. We discuss a new measure of effectiveness of carbon sequestration in a leaky reservoir, which we denote sequestration potential. The sequestration potential is the fraction of global warning cost avoided by sequestration in a reservoir. We show how these measures apply to permanent sequestration and sequestration in leaky reservoirs, such as the oceans, terrestrial biosphere, and some geologic formations. Under the assumptions of a constant cost of carbon emission and a 4% discount rate, injecting 900 m deep in the ocean avoids {approx}90% of the global warming cost associated with atmospheric emission; an injection 1700 m deep would avoid > 99 % of the global warming cost. Hence, for discount rates in the range commonly used by commercial enterprises, oceanic direct injection may be nearly as economically effective as …
Date: April 24, 2001
Creator: Caldeira, K; Herzog, H J & Wickett, M E
System: The UNT Digital Library
Uranyl-Fluoride (233U) Solutions in Spherical Stainless Steel Vessels with Reflectors of Be, CH2, and Be-CH2 Composites (open access)