The erosion/corrosion of small superalloy turbine rotors operating in the effluent of a PFB coal combustor

Superalloy turbine rotors in a single stage turbine with 6 percent partial admittance were operated in the effluent of a pressurized fluidized bed coal combustor for up to 164 hours. Total mass flow was 300 kg/hr and average particulate loadings ranged from 600 to 2800 ppm for several coal/sorbent combinations. A 5.5 atm turbine inlet gas pressure and inlet gas temperatures from 700 to 800 C yielded absolute gas velocities at the stator exit of about 500 m/s. The angular rotation speed (40,000 rpm) of the six inch diameter rotors was equivalent to a tip speed of about 300 m/s, and average gas velocities relative to the rotating surface ranged from 260 to 330 m/s at mean radius. The rotor erosion pattern reflects heavy particle separation with severe (5 to 500 cm/yr) erosion at the leading edge, pressure side center, and suction side trailing edge at the tip. The erosion distribution pattern provides a spectrum of erosion/oxidation/deposition as a function of blade position. This spectrum includes enhanced oxidation (10 to 100 x air), mixed oxides in exposed depletion zones, sulfur rich oxides in deposition zones, and rugged areas of erosive oxide removal

Developing a second generation Laue lens prototype: high reflectivity crystals and accurate assembly

Laue lenses are an emerging technology that will enhance gamma-ray telescope sensitivity by one to two orders of magnitude in selected energy bands of the \sim 100 keV to \sim 1.5 MeV range. This optic would be particularly well adapted to the observation of faint gamma ray lines, as required for the study of Supernovae and Galactic positron annihilation. It could also prove very useful for the study of hard X-ray tails from a variety of compact objects, especially making a difference by providing sufficient sensitivity for polarization to be measured by the focal plane detector. Our group has been addressing the two key issues relevant to improve performance with respect to the first generation of Laue lens prototypes: obtaining large numbers of efficient crystals and developing a method to fix them with accurate orientation and dense packing factor onto a substrate. We present preliminary results of an on-going study aiming to enable a large number of crystals suitable for diffraction at energies above 500 keV. In addition, we show the first results of the Laue lens prototype assembled using our beamline at SSL/UC Berkeley, which demonstrates our ability to orient and glue crystals with accuracy of a few arcsec, as required for an efficient Laue lens telescope.Comment: Published in the proceedings of the SPIE conference held in San Diego in August 201

Sudden To Adiabatic Transition in Beta Decay

We discuss effects in beta decays at very low beta energies, of the order of the kinetic energies of atomic electrons. As the beta energy is lowered the atomic response changes from sudden to adiabatic. As a consequence, the beta decay rate increases slightly and the ejection of atomic electrons (shake off) and subsequent production of X rays is turned off. We estimate the transition energy and the change in decay rate. The rate increase is largest in heavy atoms, which have a small Q value in their decay. The X ray switch-off is independent of Q value.Comment: 6 pages LaTe

Inherited pericentric inversion of chromosome number two: A linkage study *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66205/1/j.1469-1809.1969.tb01629.x.pd

Quasi-particle Density in Sr2RuO4 Probed by means of the Phonon Thermal Conductivity

The thermal conductivity of Sr2RuO4 along the least conducting direction perpendicular to the RuO2 plane has been studied down to 0.3 K. In this configuration the phonons remain the dominant heat carriers down to the lowest temperature, and their conductivity in the normal state is determined by the scattering on conduction electrons. We show that the phonon mean free path in the superconducting state is sensitive to the density of the quasi-particles in the bulk. An unusual magnetic field dependence of the phonon thermal conductivity is ascribed to the anisotropic superconducting gap structure in Sr2RuO4.Comment: 14 pages, 6 eps figures, Latex. This article corresponds to the reference 25 of Phys. Rev. Lett. vol.86 page2649-2652 (2001) and cond-mat/010449

X-ray Photoelectron Spectroscopy (XPS) and Magnetization Studies of Iron–Vanadium Phosphate Glasses

Vanadium phosphate glasses containing Fe2O3 with the chemical composition [(Fe2O3)x(V2O5)0.6−x(P2O5)0.4], where x=0.00, 0.10, 0.20, 0.25 and 0.30, have been prepared and investigated by X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility measurements. The core level binding energies of V 2p, Fe 2p, P 2p and P 2s in the Fe2O3–vanadium phosphate glasses have been measured and shifts from the corresponding binding energies measured for V2O5, Fe2O3 and P2O5 powders are accounted for by changes in the next-nearest neighbor environment of these atoms in the P4O10 local structure. The O 1s spectra for the glasses are single, symmetric peaks arising from nearly 95% of the oxygen sites being occupied by non-bridging oxygen atoms. In addition, the broadened V 2p3/2 and Fe 2p3/2 spectra for the glass samples are decomposed into two peaks that are associated with the presence of V5+ and V4+ and Fe3+ and Fe2+, respectively. The magnetic susceptibility data appear to follow a Curie–Weiss behavior (χ=C/(T−θ)) for temperatures above ∼15 K with negative paramagnetic Curie temperatures indicative of antiferromagnetic interactions between the magnetic Fe3+, Fe2+ and V4+ ions. The experimentally determined Curie constants from the susceptibility data are in good agreement with the calculated values based on the Fe3+, Fe2+ and V4+ concentrations determined from the XPS analyses. Other qualitative features in the magnetic susceptibility results can be explained in terms of the formation of various magnetic clusters (single, dimer and trimer) with the introduction of the magnetic ions onto the P sites of the P4O10 structure

The rarity of terrestrial gamma-ray flashes

We report on the first search for Terrestrial Gamma-ray Flashes (TGFs) from altitudes where they are thought to be produced. The Airborne Detector for Energetic Lightning Emissions (ADELE), an array of gamma-ray detectors, was flown near the tops of Florida thunderstorms in August/September 2009. The plane passed within 10 km horizontal distance of 1213 lightning discharges and only once detected a TGF. If these discharges had produced TGFs of the same intensity as those seen from space, every one should have been seen by ADELE. Separate and significant nondetections are established for intracloud lightning, negative cloud-to-ground lightning, and narrow bipolar events. We conclude that TGFs are not a primary triggering mechanism for lightning. We estimate the TGF-to-flash ratio to be on the order of 10^(−2) to 10^(−3) and show that TGF intensities cannot follow the well-known power-law distribution seen in earthquakes and solar flares, due to our limits on the presence of faint events

An Assessment of a 15 vs. 30 Second Recovery Period on Vertical Jump Performance

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Assessing the Impact of a Governed Focal Point on Broad Jump Performance in Collegiate Females

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