Improved high pressure turbine shroud

A new high pressure turbine shroud material has been developed from the consolidation of prealloyed powders of Ni, Cr, Al and Y. The new material, a filler for cast turbine shroud body segments, is called Genaseal. The development followed the identification of oxidation resistance as the primary cause of prior shroud deterioration, since conversion to oxides reduces erosion resistance and increases spalling under thermal cycled engine conditions. The NICrAlY composition was selected in preference to NIAL and FeCRALY alloys, and was formulated to a prescribed density range that offers suitable erosion resistance, thermal conductivity and elastic modulus for improved behavior as a shroud

Quasiclassical approach to the spin-Hall effect in the two-dimensional electron gas

We study the spin-charge coupled transport in a two-dimensional electron system using the method of quasiclassical ($\xi$-integrated) Green's functions. In particular we derive the Eilenberger equation in the presence of a generic spin-orbit field. The method allows us to study spin and charge transport from ballistic to diffusive regimes and continuity equations for spin and charge are automatically incorporated. In the clean limit we establish the connection between the spin-Hall conductivity and the Berry phase in momentum space. For finite systems we solve the Eilenberger equation numerically for the special case of the Rashba spin-orbit coupling and a two-terminal geometry. In particular, we calculate explicitly the spin-Hall induced spin polarization in the corners, predicted by Mishchenko et al. [13]. Furthermore we find universal spin currents in the short-time dynamics after switching on the voltage across the sample, and calculate the corresponding spin-Hall polarization at the edges. Where available, we find perfect agreement with analytical results.Comment: 9 pages, 6 figure

Sum rules for spin-Hall conductivity cancelation

It has been shown recently that the universal dc spin conductivity of two-dimensional electrons with a Rashba spin-orbit interaction is canceled by vertex corrections in a weak scattering regime. We prove that the zero bulk spin conductivity is an intrinsic property of the free-electron Hamiltonian and scattering is merely a tool to reveal this property in terms of the diagrammatic technique. When Zeeman energy is neglected, the zero dc conductivity persists in a magnetic field. Spin conductivity increases resonantly at the cyclotron frequency and then decays towards the universal value.Comment: 4 pages, 1 figur

Non-Symmetrical Loads in a Model Grain Bin During Eccentric Discharge

Eccentric discharge imposes non-symmetrical bin wall and floor loads. A series of tests were conducted for different eccentric discharge orifice locations. Floor loads during eccentric discharge of 0.61 m diameter model bin were smaller on the side nearest the discharge orifice than on the opposite side. The horizontal pressure distribution around the circumference of the bin wall depends on the height of grain above the floor

Electronic Aharonov-Bohm Effect Induced by Quantum Vibrations

Mechanical displacements of a nanoelectromechanical system (NEMS) shift the electron trajectories and hence perturb phase coherent charge transport through the device. We show theoretically that in the presence of a magnetic feld such quantum-coherent displacements may give rise to an Aharonov-Bohm-type of effect. In particular, we demonstrate that quantum vibrations of a suspended carbon nanotube result in a positive nanotube magnetoresistance, which decreases slowly with the increase of temperature. This effect may enable one to detect quantum displacement fluctuations of a nanomechanical device.Comment: 4 pages, 3 figure

Forces on Temperature Cables in a Model Bin Under Restrained Conditions

Temperature cables restrained from lateral movement, were measured as a function of grain height, cable location and surface coating. For the restrained conditions, the cable forces were one to nine times those previously measured for unrestrained cables. The large load increase on the restrained cables is believed to be caused by the flow profile which existed at each of the three different cable locations. The flow profile at the center cable is predominantly vertical and the forces in the restrained condition resembled those in the unrestrained condition. For the two outer cable locations, both vertical and lateral force components exist because of the nature of the discharging grain at these two different locations. For the restrained condition, the largest forces occurred on the cable located at the middle position. For the unrestrained condition, the largest forces occurred on the cable located at the wall position. Surface coatings on the cable had an effect on the magnitude of the forces. Forces on vinyl coated cables were significantly larger than either the nylon or HDLE polyethylene coated cables in the restrained condition

Measurement of energy eigenstates by a slow detector

We propose a method for a weak continuous measurement of the energy eigenstates of a fast quantum system by means of a "slow" detector. Such a detector is only sensitive to slowly-changing variables, e. g. energy, while its back-action can be limited solely to decoherence of the eigenstate superpositions. We apply this scheme to the problem of detection of quantum jumps between energy eigenstates in a harmonic oscillator.Comment: 4 page

Crossover from diffusive to non-diffusive dynamics in the two-dimensional electron gas with Rashba spin-orbit coupling

We present the calculation of the density matrix response function of the two-dimensional electron gas with Rashba spin-orbit interaction, which is applicable in a wide range of parameters covering the diffusive and non-diffusive, the dirty and the clean limits. A description of the crossover between the different regimes is thus provided as well. On the basis of the derived microscopic expressions we study the propagating charge and spin-polarization modes in the clean, non-diffusive regime, which is accessible in the modern experiments.Comment: 8 pages, 6 figures, a considerable extension of the first versio

Wheat Loads and Vertical Pressure Distribution in a Full-scale Bin Part II—Detention

The vertical loads imposed on a full-scale bin floor by wheat were measured during a storage time of 6 h. The floor loads were determined to be dependent on the length of storage time. A linear regression model was developed to predict this change in loads in relation to detention time. The linear regression equation had coefficient of determination values ranging from 0.230 to 0.817. Analysis of the model slopes also indicated that fill height and radial location affect the vertical floor loads with a statistical significance level of 0.05. The radial distribution of vertical pressure during detention was measured. The vertical pressure distribution is dependent on radial location and is not uniformly distributed. Radial location significantly influenced the vertical pressure at the 0.05 significance level. The distribution pattern is similar to the filling condition