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SALT FOG TEST OF SAM2X5 COATED STAINLESS STEEL CYLINDER (open access)

SALT FOG TEST OF SAM2X5 COATED STAINLESS STEEL CYLINDER

A salt fog test of an iron-based amorphous metal, SAM2X5, coated Type 316L stainless steel (SS316L) cylinder was made. The cylinder was 30-inch diameter by 88-inch long, and 3/8-inch thick. One end was welded shut with a SS316L end cap before coating. The body of the cylinder and the end cap were both coated. The cylinder was coated with SAM2X5 by the HVOF thermal spray process. The coating thickness was 0.015-inch to 0.019-inch thick. The cylinder was tested in a horizontal position. Also included in the test for reference purposes were five coupons (2-inch x 2-inch x 1/8-inch) of uncoated Type 1018 carbon steel (1018CS). The test used an abbreviated form of GM 9540P. Each cycle was 6 hours in duration and the cylinder and reference samples were exposed to a total of eight cycles. The cylinder was in relatively good condition after the test. Along the body of the cylinder only two pinpoint spot sized signs of rust were seen. The 1018CS reference specimens were extensively rusted.
Date: April 23, 2007
Creator: Aprigliano, L F; Rebak, R B; Choi, J; Lian, T & Day, S D
System: The UNT Digital Library
Landscape predictions from cosmological vacuum selection (open access)

Landscape predictions from cosmological vacuum selection

In Bousso-Polchinski models with hundreds of fluxes, we compute the effects of cosmological dynamics on the probability distribution of landscape vacua. Starting from generic initial conditions, we find that most fluxes are dynamically driven into a different and much narrower range of values than expected from landscape statistics alone. Hence, cosmological evolution will access only a tiny fraction of the vacua with small cosmological constant. This leads to a host of sharp predictions. Unlike other approaches to eternal inflation, the holographic measure employed here does not lead to staggering, an excessive spread of probabilities that would doom the string landscape as a solution to the cosmological constant problem.
Date: April 23, 2007
Creator: Bousso, Raphael; Bousso, Raphael & Yang, Sheng
System: The UNT Digital Library
Production of a sterile species: Quantum kinetics (open access)

Production of a sterile species: Quantum kinetics

Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is tau(dec)=2/Gamma(aa), but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: Gamma(1)=Gamma(aa)cos^2theta(m); Gamma(2)=Gamma(aa)sin^2theta(m) where Gamma(aa) is the interaction rate of the active species in the absence of mixing and theta(m) the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the"polarization vector" and show their equivalence to those obtained from the quantum master equation and effective …
Date: April 23, 2007
Creator: Ho, Chiu Man; Boyanovsky, D. & Ho, C.M.
System: The UNT Digital Library
3D Magnetotelluic characterization of the Coso GeothermalField (open access)

3D Magnetotelluic characterization of the Coso GeothermalField

Electrical resistivity may contribute to progress inunderstanding geothermal systems by imaging the geometry, bounds andcontrolling structures in existing production, and thereby perhapssuggesting new areas for field expansion. To these ends, a dense grid ofmagnetotelluric (MT) stations plus a single line of contiguous bipolearray profiling has been acquired over the east flank of the Cosogeothermal system. Acquiring good quality MT data in producing geothermalsystems is a challenge due to production related electromagnetic (EM)noise and, in the case of Coso, due to proximity of a regional DCintertie power transmission line. To achieve good results, a remotereference completely outside the influence of the dominant source of EMnoise must be established. Experimental results so far indicate thatemplacing a reference site in Amargosa Valley, NV, 65 miles from the DCintertie, isstill insufficient for noise cancellation much of the time.Even though the DC line EM fields are planar at this distance, theyremain coherent with the nonplanar fields in the Coso area hence remotereferencing produces incorrect responses. We have successfully unwrappedand applied MT times series from the permanent observatory at Parkfield,CA, and these appear adequate to suppress the interference of thecultural EM noise. The efficacy of this observatory is confirmed bycomparison to stations taken using an ultra-distant …
Date: April 23, 2007
Creator: Newman, Gregory A.; Hoversten, G. Michael; Wannamaker, Philip E. & Gasperikova, Erika
System: The UNT Digital Library
High Power Picosecond Laser Pulse Recirculation (open access)

High Power Picosecond Laser Pulse Recirculation

We propose a novel high peak power ultrashort laser pulse re-circulation technique suitable for gamma-ray generation in Compton-backscattering sources. The two primary obstacles to higher average brightness and conversion efficiency of laser pulse energy to gamma-rays are the relatively small Compton scattering cross-section and the typically low repetition rates of Joule-class interaction lasers (10 Hz). Only a very small fraction (10{sup -10}) of the available laser photons is converted to gamma-rays, while the bulk is discarded. To significantly reduce the average power requirements of the laser and increase the overall system efficiency, we can re-circulate laser light for repeated interactions.
Date: April 23, 2007
Creator: Shverdin, M; Jovanovic, I; Gibson, D; Hartemann, F; Brown, C; Anderson, S et al.
System: The UNT Digital Library
Modeling HCCI using CFD and Detailed Chemistry with Experimental Validation and a Focus on CO Emissions (open access)

Modeling HCCI using CFD and Detailed Chemistry with Experimental Validation and a Focus on CO Emissions

Multi-zone CFD simulations with detailed kinetics were used to model engine experiments performed on a diesel engine that was converted for single cylinder, HCCI operation, here using iso-octane as the fuel. The modeling goals were to validate the method (multi-zone combustion modeling) and the reaction mechanism (LLNL 857 species iso-octane), both of which performed very well. The purpose of this paper is to document the validation findings and to set the ground work for further analysis of the results by first looking at CO emissions characteristics with varying equivalence ratio.
Date: April 23, 2007
Creator: Hessel, R.; Foster, D.; Aceves, S.; Flowers, D.; Pitz, B.; Dec, J. et al.
System: The UNT Digital Library