Effect of the environment and alloy composition on the electrochemical behavior of Ni-Cr-Mo Alloys (open access)

Effect of the environment and alloy composition on the electrochemical behavior of Ni-Cr-Mo Alloys

Alloy 22 (UNS N06022) is the candidate material for the corrosion resistant, outer barrier of the Yucca Mountain nuclear waste containers. One of the potential corrosion degradation modes of the container is uniform or passive corrosion. Therefore it is of importance to understand the stability of the oxide film, which will control the passive corrosion rate of Alloy 22. Many variables such as temperature, composition and pH of the electrolyte, applied potential, and microstructure and composition of the base metal would determine the thickness and composition of the oxide film. The purpose of this research work was to use electrochemical and surface analysis techniques to explore the influence of solution pH and applied potential on the characteristics of the oxide film formed on Alloy 22 and two experimental alloys containing differing amounts of chromium (Cr) and molybdenum (Mo). Results confirm that bulk metal composition is fundamental to the passive behavior and potential breakdown of the studied alloys. In these preliminary results, welded and non-welded Alloy 22 did not show differences in their anodic behavior.
Date: January 5, 2004
Creator: Hayes, J R; Szmodis, A W; Anderson, K L & Orme, C A
Object Type: Article
System: The UNT Digital Library
Search for New Physics at a Super-B Factory (open access)

Search for New Physics at a Super-B Factory

The importance of a Super-B Factory in the search for New Physics, in particular, due to CP-od phase(s) from physics beyond the Standard Model is surveyed. The first point to emphasize is that we know now how to directly measure all three angles of the unitarity triangle very cleanly, i. e. without theoretical assumptions with irreducible theory error {le} 1%; however this requires much more luminosity than is currently available at B-factories. Direct searches via penguin-dominated hadronic modes as well as radiative, pair-leptonic and semi-leptonic decays are also discussed. Null tests of the SM are stressed as these will play a crucial role especially if the effects of BSM phase(s) on B-physics are small.
Date: January 5, 2004
Creator: Browder, T. E. & Soni, A.
Object Type: Article
System: The UNT Digital Library
Poroelastic Fluid Effects on Shear for Rocks with Soft Anisotropy (open access)

Poroelastic Fluid Effects on Shear for Rocks with Soft Anisotropy

None
Date: January 5, 2004
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Energy Efficient Building Equipment and Envelope Technologies: Final Report (open access)

Energy Efficient Building Equipment and Envelope Technologies: Final Report

Objectives of this project under this cooperative agreement are to evaluate the energy efficiency and performance enhancements of a pulsed thermal expansion valve (TXV), its cost and reliability. This device could replace the currently used devices, a capillary tube and modulating TXVs, in household and commercial refrigeration and air conditioners. Determination of the economics and first cost of such devices, once performance enhancements have been defined, shall be performed and reported. This work shall be accomplished with the support of commercial partners in the HVAC and R industries. The reliability of the pulsed TXV shall also be determined, which is an important factor for its commercial success.
Date: January 5, 2004
Creator: Rockenfeller, Uwe
Object Type: Report
System: The UNT Digital Library
Acoustic Detecting and Locating Gas Pipe Line Infringement Quarterly Report: Number 6 (open access)

Acoustic Detecting and Locating Gas Pipe Line Infringement Quarterly Report: Number 6

The power point presentation for the Natural Gas Technologies II Conference held on February 8-11, 2004 in Phoenix AZ, published the presentations made at the conference, therefore required all presenters to submit their presentation prior to November 2003. However in the remainder of year, significant new test data became available which were incorporated in the actual presentation made at the Natural Gas Technologies II Conference. The 6th progress report presents the updated actual slide show used during the paper presentation by Richard Guiler.
Date: January 5, 2004
Creator: LOTH, John L.; MORRIS, GARY J.; PALMER, GEORGE M. & GUILER, RICHARD
Object Type: Report
System: The UNT Digital Library
Taste changing in staggered quarks (open access)

Taste changing in staggered quarks

The authors present results from a systematic perturbative investigation of taste-changing in improved staggered quarks. They show one-loop taste-changing interactions can be removed perturbatively by an effective four-quark term and calculate the necessary coefficients.
Date: January 5, 2004
Creator: Mason, Quentin
Object Type: Article
System: The UNT Digital Library
A relativistic O (a{sup 2}) improved action for heavy quarks (open access)

A relativistic O (a{sup 2}) improved action for heavy quarks

The authors extend the Fermilab formalism for heavy quarks to develop an {Omicron}(a{sup 2}) improved relativistic action. They discuss their construction of the action, including the identification of redundant operators and the calculation of the improvement coefficients.
Date: January 5, 2004
Creator: al., M. B. Oktay et
Object Type: Article
System: The UNT Digital Library
Determining the mechanical constitutive properties of metals as a function of strain rate and temperature: A combined experimental and modeling approach (open access)

Determining the mechanical constitutive properties of metals as a function of strain rate and temperature: A combined experimental and modeling approach

OAK-135 Development and validation of constitutive models for polycrystalline materials subjected to high strain rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions (foreign object damage, high-strain rate forging, high-speed sheet forming, deformation behavior during forming, response to extreme conditions, etc.). To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be closely coupled with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experimentation is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with …
Date: January 5, 2004
Creator: Robertson, I. M.; Beaudoin, A. & Lambros, J.
Object Type: Report
System: The UNT Digital Library
Three-dimensional Global Model Approaches to Understanding Stratospheric Impacts on Tropospheric Ozone (open access)

Three-dimensional Global Model Approaches to Understanding Stratospheric Impacts on Tropospheric Ozone

None
Date: January 5, 2004
Creator: Atherton, C; Bergmann, D; Cameron-Smith, P; Connell, P; Dignon, J; Rotman, D et al.
Object Type: Article
System: The UNT Digital Library
Simple Derivation of the Hauser-Feshbach and Weisskopf-Ewing Formulae, with Application to Surrogate Reactions (open access)

Simple Derivation of the Hauser-Feshbach and Weisskopf-Ewing Formulae, with Application to Surrogate Reactions

The analysis of surrogate reactions, an indirect technique for determining cross sections on unstable nuclei, relies heavily on compound-nuclear reaction models. The purpose of this tutorial is to provide an introduction to the principal models, based on the Hauser-Feshbach and Weisskopf-Ewing formalisms, and to show how they are applied to surrogate reactions.
Date: January 5, 2004
Creator: Dietrich, F S
Object Type: Report
System: The UNT Digital Library
Hydra observations of aluminum abundances in the red giants ofthe globular clusters M80 and NGC 6752 (open access)

Hydra observations of aluminum abundances in the red giants ofthe globular clusters M80 and NGC 6752

Aluminum and other metal abundances were determined in 21 red giants in the globular clusters NGC 6752 and M80 as part of a larger study to determine whether the aluminum distribution on the red giant branch is related to the second parameter effect that causes clusters of similar metallicity to display different horizontal branch morphologies. The observations were obtained of the Al I lines near 6700 Angstroms with the CTIO Blanco 4-m telescope and Hydra multi-object spectrograph. The spectra have a resolving power of 18000 or 9400, with typical S/N ratios of 100-200. Mean [Fe/H] values obtained from the spectra are -1.58 for NGC 6751 and -1.73 for M80; this represents the spectroscopic iron abundance determination for M80. Both NGC 6752 and M80 display a spread in aluminum abundance with mean [Al/Fe] ratios of +0.51 and +0.37 respectively. No trend in the variation of the mean AI abundance with position on the giant branch is discernible in either cluster with our small sample.
Date: January 5, 2004
Creator: Suntzeff, N B; Cavallo, R M & Pilachowski, C A
Object Type: Article
System: The UNT Digital Library
The National Ignition Facility: Laser System, Beam Line Design and Construction (open access)

The National Ignition Facility: Laser System, Beam Line Design and Construction

The construction of the National Ignition Facility (NIF) building and laser beampaths at the Lawrence Livermore National Laboratory has been completed. This 8-year design/construction effort has successfully erected a 450,000 sq ft building and filled its interior with a complex of large-scale optical benches. These benches support all of the large-aperture optic elements of the NIF and the environmentally controlled enclosures that protect each of the 192 laser beamlines as they propagate from the injection laser system, through large aperture amplification stages, and into the target chamber. Even though this facility is very large, nearly 200 m long, 100 m wide, and 30 m tall, stringent mechanical performance requirements have been achieved throughout including temperature control <0.3 C, laser-beam pointing stability on target < 50 {micro}rms, and level 100 surface cleanliness on internal components. This presentation will provide an historical perspective explaining the basis of the design, technical details describing the techniques of construction and a chronological progression of the construction activities from ground breaking to beampath completion.
Date: January 5, 2004
Creator: Sawicki, R H
Object Type: Article
System: The UNT Digital Library
The National Ignition Facility Wavefront Requirements and Optical Architecture (open access)

The National Ignition Facility Wavefront Requirements and Optical Architecture

With the first four of its eventual 192 beams now executing shots, the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is already the world's largest and most energetic laser. The optical system performance requirements that are in place for NIF are derived from the goals of the missions it is designed to serve. These missions include inertial confinement fusion (ICF) research and the study of matter at extreme energy densities and pressures. These mission requirements have led to a design strategy for achieving high quality focusable energy and power from the laser and to specifications on optics that are important for an ICF laser. The design of NIF utilizes a multipass architecture with a single large amplifier type that provides high gain, high extraction efficiency and high packing density. We have taken a systems engineering approach to the practical implementation of this design that specifies the wavefront parameters of individual optics in order to achieve the desired cumulative performance of the laser beamline. This presentation provides a detailed look at the causes and effects of performance degradation in large laser systems and how NIF has been designed to overcome these effects. We will also present results of …
Date: January 5, 2004
Creator: Spaeth, M. L.; Manes, K. R.; Widmayer, C. C.; Williams, W.; Whitman, P. A. & Henesian, M.
Object Type: Article
System: The UNT Digital Library
Actinic Mask Inspection at the Als: Risk Reduction Activities for 2003 (open access)

Actinic Mask Inspection at the Als: Risk Reduction Activities for 2003

This document reports on risk reduction activities performed at the VNL during CY2003 as a part of the Lith-343 actinic inspection project funded by International SEMATECH. The risk reduction activities described in this document comprise deliverable items 3.1.3, 3.1.4, 3.1.5 and 3.1.6 of Amendment 6 to the VNL EUV mask blank technology transfer contract.
Date: January 5, 2004
Creator: Barty, A.; Levesque, R.; Ayers, J.; Liu, Y.; Gullikson, E. & Barale, P.
Object Type: Report
System: The UNT Digital Library
Magnetorheological Finishing for Imprinting Continuous Phase Plate Structure onto Optical Surfaces (open access)

Magnetorheological Finishing for Imprinting Continuous Phase Plate Structure onto Optical Surfaces

Magnetorheological finishing (MRF) techniques have been developed to manufacture continuous phase plates (CPP's) and custom phase corrective structures on polished fused silica surfaces. These phase structures are important for laser applications requiring precise manipulation and control of beam-shape, energy distribution, and wavefront profile. The MRF's unique deterministic-sub-aperture polishing characteristics make it possible to imprint complex topographical information onto optical surfaces at spatial scale-lengths approaching 1 mm. In this study, we present the results of experiments and model calculations that explore imprinting two-dimensional sinusoidal structures. Results show how the MRF removal function impacts and limits imprint fidelity and what must be done to arrive at a high quality surface. We also present several examples of this imprinting technology for fabrication of phase correction plates and CPPs for use at high fluences.
Date: January 5, 2004
Creator: Menapace, J A; Dixit, S N; Genin, F Y & Brocious, W F
Object Type: Article
System: The UNT Digital Library
Introduction to the National Ignition Facility (open access)

Introduction to the National Ignition Facility

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. NIF will be the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion and matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear bum, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} bar, conditions that exist naturally only in the interior of stars, planets and in nuclear weapons. NIF has completed the first phases of its laser commissioning program. The first four beams of NIF have generated 106 kilojoules of infrared light and over 16 kJ at the third harmonic (351 nm). NIF's target experimental systems are being commissioned and experiments have begun. This paper provides a detailed look the NIF laser systems, laser and optical performance and results from recent laser commissioning shots, and plans for commissioning diagnostics for experiments on NIF.
Date: January 5, 2004
Creator: Moses, E I
Object Type: Article
System: The UNT Digital Library
Length-Limited Variable-to-Variable Length Codes for High-Performance Entropy Coding (open access)

Length-Limited Variable-to-Variable Length Codes for High-Performance Entropy Coding

Arithmetic coding achieves a superior coding rate when encoding a binary source, but its lack of speed makes it an inferior choice when true high-performance encoding is needed. We present our work on a practical implementation of fast entropy coders for binary messages utilizing only bit shifts and table lookups. To limit code table size we limit our code lengths with a type of variable-to-variable (VV) length code created from source string merging. We refer to these codes as ''merged codes''. With merged codes it is possible to achieve a desired level of speed by adjusting the number of bits read from the source at each step. The most efficient merged codes yield a coder with a worst-case inefficiency of 0.4%, relative to the Shannon entropy. Using a hybrid Golomb-VV Bin Coder we are able to achieve a compression ratio that is competitive with other state-of-the-art coders, at a superior throughput.
Date: January 5, 2004
Creator: Duchaineau, Mark; Senecal, Joshua & Joy, Kenneth I.
Object Type: Article
System: The UNT Digital Library
Terahertz radiation from laser accelerated electron bunches (open access)

Terahertz radiation from laser accelerated electron bunches

Coherent terahertz and millimeter wave radiation from laser accelerated electron bunches has been measured. The bunches were produced by tightly focusing (spot diameter {approx} 6 {micro}m) a high peak power (up to 10 TW), ultra-short ({ge}50 fs) laser pulse from a high repetition rate (10 Hz) laser system (0.8 {micro}m), onto a high density (>10{sup 19} cm{sup -3}) pulsed gas jet of length {approx} 1.5 mm. As the electrons exit the plasma, coherent transition radiation is generated at the plasma-vacuum boundary for wavelengths long compared to the bunch length. Radiation in the 0.3-19 THz range and at 94 GHz has been measured and found to depend quadratically on the bunch charge. The measured radiated energy for two different collection angles is in good agreement with theory. Modeling indicates that optimization of this table-top source could provide more than 100 {micro}J/pulse. Together with intrinsic synchronization to the laser pulse, this will enable numerous applications requiring intense terahertz radiation. This radiation can also be used as a powerful tool for measuring the properties of laser accelerated bunches at the exit of the plasma accelerator. Preliminary spectral measurements indicates that bunches as short as 30-50 fs have been produced in these laser driven …
Date: January 5, 2004
Creator: Leemans, W. P.; van Tilborg, J.; Faure, J.; Geddes, C. G. R.; Toth, Cs.; Schroe der, C. B. et al.
Object Type: Article
System: The UNT Digital Library