In-Situ Observations of Sigma Phase Dissolution in 2205 Duplex Stainless Steel using Synchrotron X-Ray Diffraction (open access)

In-Situ Observations of Sigma Phase Dissolution in 2205 Duplex Stainless Steel using Synchrotron X-Ray Diffraction

Synchrotron radiation was used to directly observe the transformation of ferrite, austenite and sigma phases during heating and cooling of 2205 duplex stainless steel. Sigma formed during the initial stages of heating, dissolved as the temperature was increased, and reformed on cooling. The dissolution temperature of sigma was measured to be 985 C {+-} 2.8 C at a heating rate of 0.25 C/s, and the kinetics of sigma formation at 850 C was determined to be slower after dissolving at 1000 C than before.
Date: August 8, 2006
Creator: Elmer, J.; Palmer, T. & Specht, E.
System: The UNT Digital Library
Angularly Adaptive P1 - Double P0 Flux-Limited Diffusion Solutions of Non-Equilibrium Grey Radiative Transfer Problems (open access)

Angularly Adaptive P1 - Double P0 Flux-Limited Diffusion Solutions of Non-Equilibrium Grey Radiative Transfer Problems

The double spherical harmonics angular approximation in the lowest order, i.e. double P{sub 0} (DP{sub 0}), is developed for the solution of time-dependent non-equilibrium grey radiative transfer problems in planar geometry. Although the DP{sub 0} diffusion approximation is expected to be less accurate than the P{sub 1} diffusion approximation at and near thermodynamic equilibrium, the DP{sub 0} angular approximation can more accurately capture the complicated angular dependence near a non-equilibrium radiation wave front. In addition, the DP{sub 0} approximation should be more accurate in non-equilibrium optically thin regions where the positive and negative angular domains are largely decoupled. We develop an adaptive angular technique that locally uses either the DP{sub 0} or P{sub 1} flux-limited diffusion approximation depending on the degree to which the radiation and material fields are in thermodynamic equilibrium. Numerical results are presented for two test problems due to Su and Olson and to Ganapol and Pomraning for which semi-analytic transport solutions exist. These numerical results demonstrate that the adaptive P{sub 1}-DP{sub 0} diffusion approximation can yield improvements in accuracy over the standard P{sub 1} diffusion approximation, both without and with flux-limiting, for non-equilibrium grey radiative transfer.
Date: August 8, 2006
Creator: Brantley, P. S.
System: The UNT Digital Library
ECRbase: Database of Evolutionary Conserved Regions, Promoters, and Transcription Factor Binding Sites in Vertebrate Genomes (open access)

ECRbase: Database of Evolutionary Conserved Regions, Promoters, and Transcription Factor Binding Sites in Vertebrate Genomes

Evolutionary conservation of DNA sequences provides a tool for the identification of functional elements in genomes. We have created a database of evolutionary conserved regions (ECRs) in vertebrate genomes entitled ECRbase that is constructed from a collection of pairwise vertebrate genome alignments produced by the ECR Browser database. ECRbase features a database of syntenic blocks that recapitulate the evolution of rearrangements in vertebrates and a collection of promoters in all vertebrate genomes presented in the database. The database also contains a collection of annotated transcription factor binding sites (TFBS) in all ECRs and promoter elements. ECRbase currently includes human, rhesus macaque, dog, opossum, rat, mouse, chicken, frog, zebrafish, and two pufferfish genomes. It is freely accessible at http://ECRbase.dcode.org.
Date: August 8, 2006
Creator: Loots, G. & Ovcharenko, I.
System: The UNT Digital Library
Dynamical Origin of Memory and Renewal (open access)

Dynamical Origin of Memory and Renewal

This article discusses a dynamical origin of memory and renewal.
Date: August 8, 2006
Creator: Cakir, Rasit; Grigolini, Paolo & Krokhin, Arkadii A.
System: The UNT Digital Library