Texture Development During Equal Channel Angular Forging of BCC Metals (open access)

Texture Development During Equal Channel Angular Forging of BCC Metals

Equal channel angular forging (ECAF) has been proposed as a severe plastic deformation technique for processing metals, alloys, and composites [e.g. Segal, 1995] (Fig. 1). The technique offers two capabilities of practical interest: a high degree of strain can be introduced with no change in the cross-sectional dimensions of the work-piece, hence, even greater strains can be introduced by re-inserting the work-piece for further deformation during subsequent passes through the ECAF die. Additionally, the deformation is accomplished by simple shear (like torsion of a short tube) on a plane whose orientation, with respect to prior deformations, can be controlled by varying the processing route. There is a nomenclature that has developed in the literature for the typical processing routes: A: no rotations; B{sub A}: 90 degrees CW (clockwise), 90 degrees CCW (counterclockwise), 9O degrees CW, 90 degrees CCW...; Bc: 90 degrees CW, 90 degrees CW, 90 degrees CW...; and C: 180 degrees, 18 0 degrees.... The impact of processing route on the subsequent microstructure [Ferasse, Segal, Hartwig and Goforth, 1997; Iwahashi, Horita, Nemoto and Langdon, 1996] and texture [Gibbs, Hartwig, Cornwell, Goforth and Payzant, 1998] has been the subject of numerous experimental studies.
Date: August 8, 1999
Creator: Agnew, S. R.
Object Type: Article
System: The UNT Digital Library
Simple Stringy Dynamical SUSY Breaking (open access)

Simple Stringy Dynamical SUSY Breaking

We present simple string models which dynamically break supersymmetry without non-Abelian gauge dynamics. The Fayet model, the Polonyi model, and the O'Raifeartaigh model each arise from D-branes at a specific type of singularity. D-brane instanton effects generate the requisite exponentially small scale of supersymmetry breaking.
Date: August 8, 2007
Creator: Aharony, Ofer; /Weizmann Inst. /Stanford U., Phys. Dept. /SLAC; Kachru, Shamit; Silverstein, Eva & /Stanford U., Phys. Dept. /SLAC
Object Type: Article
System: The UNT Digital Library
Probing Dark Energy via Weak Gravitational Lensing with the Supernova Acceleration Probe (SNAP) (open access)

Probing Dark Energy via Weak Gravitational Lensing with the Supernova Acceleration Probe (SNAP)

SNAP is a candidate for the Joint Dark Energy Mission (JDEM) that seeks to place constraints on the dark energy using two distinct methods. The first, Type Ia SN, is discussed in a separate white paper. The second method is weak gravitational lensing, which relies on the coherent distortions in the shapes of background galaxies by foreground mass structures. The excellent spatial resolution and photometric accuracy afforded by a 2-meter space-based observatory are crucial for achieving the high surface density of resolved galaxies, the tight control of systematic errors in the telescope's Point Spread Function (PSF), and the exquisite redshift accuracy and depth required by this project. These are achieved by the elimination of atmospheric distortion and much of the thermal and gravity loads on the telescope. The SN and WL methods for probing dark energy are highly complementary and the error contours from the two methods are largely orthogonal. The nominal SNAP weak lensing survey covers 1000 square degrees per year of operation in six optical and three near infrared filters (NIR) spanning the range 350 nm to 1.7 {micro}m. This survey will reach a depth of 26.6 AB magnitude in each of the nine filters and allow for …
Date: August 8, 2005
Creator: Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J. et al.
Object Type: Report
System: The UNT Digital Library
Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae (open access)

Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae

The Supernova Acceleration Probe (SNAP) will use Type Ia supernovae (SNe Ia) as distance indicators to measure the effect of dark energy on the expansion history of the Universe. (SNAP's weak-lensing program is described in a separate White Paper.) The experiment exploits supernova distance measurements up to their fundamental systematic limit; strict requirements on the monitoring of each supernova's properties leads to the need for a space-based mission. Results from pre-SNAP experiments, which characterize fundamental SN Ia properties, will be used to optimize the SNAP observing strategy to yield data, which minimize both systematic and statistical uncertainties. With early R&D funding, we have achieved technological readiness and the collaboration is poised to begin construction. Pre-JDEM AO R&D support will further reduce technical and cost risk. Specific details on the SNAP mission can be found in Aldering et al. (2004, 2005). The primary goal of the SNAP supernova program is to provide a dataset which gives tight constraints on parameters which characterize the dark-energy, e.g. w{sub 0} and w{sub a} where w(a) = w{sub 0} + w{sub a}(1-a). SNAP data can also be used to directly test and discriminate among specific dark energy models. We will do so by building the …
Date: August 8, 2005
Creator: Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J. et al.
Object Type: Report
System: The UNT Digital Library
Information, complexity and efficiency: The automobile model (open access)

Information, complexity and efficiency: The automobile model

The new, rapidly evolving field of industrial ecology - the objective, multidisciplinary study of industrial and economic systems and their linkages with fundamental natural systems - provides strong ground for believing that a more environmentally and economically efficient economy will be more information intensive and complex. Information and intellectual capital will be substituted for the more traditional inputs of materials and energy in producing a desirable, yet sustainable, quality of life. While at this point this remains a strong hypothesis, the evolution of the automobile industry can be used to illustrate how such substitution may, in fact, already be occurring in an environmentally and economically critical sector.
Date: August 8, 1996
Creator: Allenby, B.
Object Type: Article
System: The UNT Digital Library
Advanced Industrial Materials (AIM) Program Compilation of Project Summaries and Significant Accomplishments FY 1999 (open access)

Advanced Industrial Materials (AIM) Program Compilation of Project Summaries and Significant Accomplishments FY 1999

For the past 10 years the Advanced Industrial Materials (AIM) has supported development of new and improved materials to enable U.S. industry to improve energy efficiency, increase productivity, and reduce waste. It has been a National Laboratory based program, with work currently under way at Oak Ridge National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories, in collaboration with industrial and university partners. With the advent of the Industries of the Future (IOF) strategy within the Office of Industrial Technologies (OIT) and the scheduled completion of the Continuous Fiber Ceramic Composites (CFCC) Program in FY 2002, an integrated materials program is being developed in OIT. So this represents the last summary of AIM research and development. The new program, Industrial Materials for the Future (IMF), will be competitive in operation, with solicitations for proposals for development of materials in accordance with the IOF Technology Roadmaps, followed by merit review and funding of the best proposals. Industry will take the lead in ''industry-specific'' research and development, in cooperation with National Laboratories, as needed. National Laboratories and universities will take the lead in maintaining a base technology program, for the purpose of maintaining a continuing flow of new materials technologies. The …
Date: August 8, 2000
Creator: Angelini, P
Object Type: Report
System: The UNT Digital Library
Evaluation of Salmon Spawning Below Bonneville Dam Annual Report October 2006 - September 2007. (open access)

Evaluation of Salmon Spawning Below Bonneville Dam Annual Report October 2006 - September 2007.

From 1999 through 2007, the Fish and Wildlife Program of the Bonneville Power Administration funded a project to determine the number of fall Chinook and chum salmon spawning downstream of Bonneville Dam, the characteristics of their spawning areas, and the flows necessary to ensure their long-term survival. Data were collected to ensure that established flow guidelines are appropriate and provide adequate protection for the species of concern. The projects objectives are consistent with the high priority placed by the Northwest Power and Conservation Council Independent Scientific Advisory Board and the salmon managers on determining the importance of mainstem habitats to the production of salmon in the Columbia River Basin. Because of the influence of mainstem habitat on salmon production, there is a continued need to better understand the physical habitat variables used by mainstem fall Chinook and chum salmon populations and the effects of hydropower project operations on spawning and incubation. During FY 2007, Pacific Northwest National Laboratory focused on (1) locating and mapping deep-water fall Chinook salmon and chum salmon spawning areas, (2) investigating the interaction between groundwater and surface water near fall Chinook and chum salmon spawning areas, and (3) providing in-season hyporheic temperature and water surface elevation …
Date: August 8, 2008
Creator: Arntzen, Evan V.; Mueller, Robert P.; Murray, Katherine J. & Bott, Yi-Ju
Object Type: Report
System: The UNT Digital Library
Probing Late Neutrino Mass Properties With SupernovaNeutrinos (open access)

Probing Late Neutrino Mass Properties With SupernovaNeutrinos

Models of late-time neutrino mass generation contain new interactions of the cosmic background neutrinos with supernova relic neutrinos (SRNs). Exchange of an on-shell light scalar may lead to significant modification of the differential SRN flux observed at earth. We consider an Abelian U(1) model for generating neutrino masses at low scales, and show that there are cases for which the changes induced in the flux allow one to distinguish the Majorana or Dirac nature of neutrinos, as well as the type of neutrino mass hierarchy (normal or inverted or quasi-degenerate). In some region of parameter space the determination of the absolute values of the neutrino masses is also conceivable. Measurements of the presence of these effects may be possible at the next-generation water Cerenkov detectors enriched with Gadolinium, or a 100 kton liquid argon detector.
Date: August 8, 2007
Creator: Baker, Joseph; Goldberg, Haim; Perez, Gilad & Sarcevic, Ina
Object Type: Article
System: The UNT Digital Library
Shield for Water Boiler (open access)

Shield for Water Boiler

Siimplified shielding calculations indicating the proposed design for the water boiler assembly will reduce the radiation at normal operaton to values well below those which are considered tolerable.
Date: August 8, 1951
Creator: Balent, R.
Object Type: Report
System: The UNT Digital Library
LCLS-II New Instruments Workshops Report (open access)

LCLS-II New Instruments Workshops Report

The LCLS-II New Instruments workshops chaired by Phil Heimann and Jerry Hastings were held on March 19-22, 2012 at the SLAC National Accelerator Laboratory. The goal of the workshops was to identify the most exciting science and corresponding parameters which will help define the LCLS-II instrumentation. This report gives a synopsis of the proposed investigations and an account of the workshop. Scientists from around the world have provided short descriptions of the scientific opportunities they envision at LCLS-II. The workshops focused on four broadly defined science areas: biology, materials sciences, chemistry and atomic, molecular and optical physics (AMO). Below we summarize the identified science opportunities in the four areas. The frontiers of structural biology lie in solving the structures of large macromolecular biological systems. Most large protein assemblies are inherently difficult to crystallize due to their numerous degrees of freedom. Serial femtosecond protein nanocrystallography, using the 'diffraction-before-destruction' approach to outrun radiation damage has been very successfully pioneered at LCLS and diffraction patterns were obtained from some of the smallest protein crystals ever. The combination of femtosecond x-ray pulses of high intensity and nanosized protein crystals avoids the radiation damage encountered by conventional x-ray crystallography with focused beams and opens the …
Date: August 8, 2012
Creator: Baradaran, Samira; Bergmann, Uwe; Durr, Herrmann; Gaffney, Kelley; Goldstein, Julia; Guehr, Markus et al.
Object Type: Article
System: The UNT Digital Library
Report of the CEBAF PAC4 Subcomittee on STAR (open access)

Report of the CEBAF PAC4 Subcomittee on STAR

This report discusses the following topics: the symmetric toroidal array (STAR) spectrometer facility; investigation of the N {yields} {Delta} transition; Hyperon production in the (e, e{prime}k) reactions; investigation of few-body systems with the (e, e{prime}p) reaction; nuclear structure studies with the (e,e{prime}pp) reaction; Measurement of G{sub Em} in a recoil polarimetry measurement; parity violation measurements; and STAR design and performance.
Date: August 8, 1990
Creator: Barnes, P. D.
Object Type: Report
System: The UNT Digital Library
Aggregation kinetics in a model colloidal suspension (open access)

Aggregation kinetics in a model colloidal suspension

The authors present molecular dynamics simulations of aggregation kinetics in a colloidal suspension modeled as a highly asymmetric binary mixture. Starting from a configuration with largely uncorrelated colloidal particles the system relaxes by coagulation-fragmentation dynamics to a structured state of low-dimensionality clusters with an exponential size distribution. The results show that short range repulsive interactions alone can give rise to so-called cluster phases. For the present model and probably other, more common colloids, the observed clusters appear to be equilibrium phase fluctuations induced by the entropic inter-colloidal attractions.
Date: August 8, 2005
Creator: Bastea, S
Object Type: Article
System: The UNT Digital Library
Use of Conducting Polymers for Electronic Communication with Redox Active Nanoparticles (open access)

Use of Conducting Polymers for Electronic Communication with Redox Active Nanoparticles

Nanoscale materials provide unique properties that will enable new technologies and enhance older ones. One area of intense activity in which nanoscale materials are being used is in the development of new functional materials for battery applications.1-4 This effort promises superior materials with properties that circumvent many of the problems associated with traditional battery materials. Previously we have worked on several approaches for using nanoscale materials for application as cathode materials in rechargeable Li batteries.5-11 Our recent work has focused on synthesizing MnO2 nanoparticles and using conducting polymers to electronically address these particles in nanoparticle assemblies. This presentation will focus on those efforts. MnO2 nanoparticles that are encapsulated with poly(3,4-ethylenedioxythiophene) (PEDOT) are prepared using 3,4-ethylenedioxythiophene (EDOT) as a chemical reductant for permanganate anion. This non-aqueous preparation is based on a recent report of a similar method for preparation of PEDOT-encapsulated Au nanoparticles.12 We also describe the synthesis of MnO2 colloidal nanoparticles prepared using an aqueous route involving reduction of permanganate anion with butanol using a previously described route.13 We report the synthesis and characterization of the PEDOT material, and the aqueous colloidal material. We show that the aqueous colloidal nanoparticles can be trapped in thin films using a layer-by-layer deposition …
Date: August 8, 2004
Creator: Bazito, Fernanda; O'Brien, Robert & Buttry, Daniel A.
Object Type: Article
System: The UNT Digital Library
Implementation of Energy-Dependent Q Values for Fission (open access)

Implementation of Energy-Dependent Q Values for Fission

We discuss how the fission Q values for {sup 235}U, {sup 238}U and {sup 239}Pu depend on the energy of the incident neutron. We then describe how these values have been implemented in mcfgen etc. This paper describes the calculation of energy-dependent fission Q values by Madland [1] and explains how it has been implemented in the ENDL database for use in the LLNL codes.
Date: August 8, 2007
Creator: Beck, B.; Brown, D. A.; Daffin, F.; Hedstrom, J. & Vogt, R.
Object Type: Report
System: The UNT Digital Library
A Proposal to Develop Electro-Optical Detection for the Temporal Characterization of Sub-Picosecond Beam Bunch. (open access)

A Proposal to Develop Electro-Optical Detection for the Temporal Characterization of Sub-Picosecond Beam Bunch.

None
Date: August 8, 2006
Creator: Ben-Zvi, Ilan; Burns, R.; Lazarus, D. M.; Semertzidis, Y. K.; Srinivasan-Rao, T. & Tsang, T.
Object Type: Report
System: The UNT Digital Library
Tank characterization report for double-shell tank 241-AN-101 (open access)

Tank characterization report for double-shell tank 241-AN-101

This document summarizes the information on the historical uses, present status, and the sampling and analysis results of waste stored in Tank 241-AN-101. This report supports the requirements of Tri-Party Agreement Milestone M-44-09.
Date: August 8, 1996
Creator: Benar, C. J.
Object Type: Report
System: The UNT Digital Library
Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys (open access)

Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys

The purpose of this study is to investigate the quench sensitivity of mechanical properties of hot extruded 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delzty time at various temperatures between 200-500 C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference.
Date: August 8, 2000
Creator: Bergsma, S C; Kassner, M E; Li, X & Rosen, R S
Object Type: Article
System: The UNT Digital Library
Formation and Reactivity of Biogenic Iron Microminerals (open access)

Formation and Reactivity of Biogenic Iron Microminerals

The overall purpose of the project is to explore and quantify the processes that control the formation and reactivity of biogenic iron microminerals and their impact on the solubility of metal contaminants. The research addresses how surface components of bacterial cells, extracellular organic material, and the aqueous geochemistry of the DIRB microenvironment impacts the mineralogy, chemical state and micromorphology of reduced iron phases.
Date: August 8, 2000
Creator: Beveridge, Terrance J.; Glasauer, Susan; Korenevsky, Anton & Ferris, F. Grant
Object Type: Report
System: The UNT Digital Library
Dislocation nucleation in bcc Ta single crystals studied by nanoindentation (open access)

Dislocation nucleation in bcc Ta single crystals studied by nanoindentation

The study of dislocation nucleation in closed-packed metals by nanoindentation has recently attracted much interest. Here, we address the peculiarities of the incipient plasticity in body centered cubic (bcc) metals using low index Ta single-crystals as a model system. The combination of nanoindentation with high-resolution atomic force microscopy provides us with experimental atomic-scale information on the process of dislocation nucleation and multiplication. Our results reveal a unique deformation behavior of bcc Ta at the onset of plasticity which is distinctly different from that of closed-packed metals. Most noticeable, we observe only one rather than a sequence of discontinuities in the load-displacement curves. This and other differences are discussed in context of the characteristic plastic deformation behavior of bcc metals.
Date: August 8, 2007
Creator: Biener, M M; Biener, J; Hodge, A M & Hamza, A V
Object Type: Article
System: The UNT Digital Library
Numerical analysis of thermal-hydrological conditions in thesingle heater test at Yucca Mountain (open access)

Numerical analysis of thermal-hydrological conditions in thesingle heater test at Yucca Mountain

The Single Heater Test (SHT) is one of two in-situ thermal tests included in the site characterization program for the potential underground nuclear waste repository at Yucca Mountain. The heating phase of the SHT started in August 1996, and was completed in May 1997 after 9 months of heating. The coupled processes in the unsaturated fractured rock mass around the heater were monitored by numerous sensors for thermal, hydrological, mechanical and chemical data. In addition to passive monitoring, active testing of the rock mass moisture content was performed using geophysical methods and air injection testing. The extensive data set available from this test gives a unique opportunity to improve the understanding of the thermal-hydrological situation in the natural setting of the repository rocks. The present paper focuses on the 3-D numerical simulation of the thermal-hydrological processes in the SHT using TOUGH2. In the comparative analysis, they are particularly interested in the accuracy of different fracture-matrix-interaction concepts such as the Effective Continuum (ECM), the Dual Continuum (DKM), and the Multiple Interacting Continua (MINC) method.
Date: August 8, 1998
Creator: Birkholzer, Jens T. & Tsang, Yvonne W.
Object Type: Report
System: The UNT Digital Library
Emerging material systems for solar cell applications (open access)

Emerging material systems for solar cell applications

Primary effort to date involves modifications and additions to the vacuum system in order to produce films of InP by the plasma-induced deposition process.
Date: August 8, 1979
Creator: Biter, W. J. & Szedon, J. R.
Object Type: Report
System: The UNT Digital Library
A New Scheme for Stigmatic X-ray Imaging with Large Magnification (open access)

A New Scheme for Stigmatic X-ray Imaging with Large Magnification

This paper describes a new x-ray scheme for stigmatic imaging. The scheme consists of one convex spherically bent crystal and one concave spherically bent crystal. The radii of curvature and Bragg reflecting lattice planes of the two crystals are properly matched to eliminate the astigmatism, so that the conditions for stigmatic imaging are met for a particular wavelength. The magnification is adjustable and solely a function of the two Bragg angles or angles of incidence. Although the choice of Bragg angles is constrained by the availability of crystals, this is not a severe limitation for the imaging of plasmas, since a particular wavelength can be selected from the bremsstrahlung continuum. The working principle of this imaging scheme has been verified with visible light. Further tests with x rays are planned for the near future. 2012 American Institute of Physics
Date: August 8, 2012
Creator: Bitter, M.; Delgado-Aprico, L. F.; Pablant, N. A.; Scott, S.; Jones, F.; Beiersdorfer, P. et al.
Object Type: Report
System: The UNT Digital Library
Past, Present, Future Erosion at Locke Island (open access)

Past, Present, Future Erosion at Locke Island

This report describes and documents the erosion that has occurred along the northeast side of Locke Island over the last 10 to 20 years. The principal cause of this erosion is the massive Locke Island landslide complex opposite the Columbia River along the White Bluffs, which constricts the flow of the river and deflects the river's thalweg southward against the island.
Date: August 8, 2006
Creator: Bjornstad, Bruce N.
Object Type: Report
System: The UNT Digital Library
Computational model of drilling with high radiance pulsed lasers (open access)

Computational model of drilling with high radiance pulsed lasers

This paper describes a model of drilling by high radiance pulsed lasers. The model contains a one-dimensional description of heat transport below the bottom of the hole, hydrodynamic expansion of the vapor and compressed air, and light propagation through the vapor. The pressure and energy of the vapor are taken from a separate Saha equilibrium code. The boundary conditions at the vaporization surface include the formation of a Knudsen layer within which macroscopic fluid conditions are reached. The absorption mechanisms in the pertinent range of densities and temperatures are photoionization and inverse bremsstrahlung. The model has been applied to the case of drilling in stainless steel with green copper laser light, for peak input intensities ranging from 10{sup 8} to 5 {times} 10{sup 10} W/cm{sup 2}. Below 3 {times} 10{sup 8} W/cm{sup 2}, their is negligible absorption in the vapor and ablation increases rapidly with intensity. Above this point, ablation still generally increases with intensity, because of a combination of partially penetrating light and electron thermal conduction to the surface. The predicted ablation rates agree semiquantitatively with experiment.
Date: August 8, 1994
Creator: Boley, C. D.
Object Type: Article
System: The UNT Digital Library