Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated

Life under the "new normal": notes on the future of preparedness

Being prepared for emergencies is not a new concept. At every level of government there are contingency plans for natural disasters, accidental catastrophes, local events and personal emergencies of every conceivable manner. Organizations from the Red Cross to the Federal Emergency Management Agency to hospital emergency departments are in a constant state of readiness. Often, regionally specific plans are in place based on expectations of particular kinds of disasters: earthquakes in the West, hurricanes on the East Coast, and tornados in the Midwest. In fact, long before 9/11, even terrorism had been on the minds of at least a handful of stalwart preparedness experts – mostly in the military and in special governmental agencies (Benjamin & Simon, 2002; Stern, 2003; Clarke, 2004). The chapters in this volume survey the state of our understanding of the psychological response to terrorism and other exigent events. It is clear that much has been learned. At the same time, many questions remain. What are the best interventions post-event? How do we recognize those in most immediate need, or those who may be most susceptible, other than those with pre-existing psychopathology? (North et al. this volume). What sorts of pre-event messages are the most useful for preparing the community

Life under the "new normal": notes on the future of preparedness

Being prepared for emergencies is not a new concept. At every level of government there are contingency plans for natural disasters, accidental catastrophes, local events and personal emergencies of every conceivable manner. Organizations from the Red Cross to the Federal Emergency Management Agency to hospital emergency departments are in a constant state of readiness. Often, regionally specific plans are in place based on expectations of particular kinds of disasters: earthquakes in the West, hurricanes on the East Coast, and tornados in the Midwest. In fact, long before 9/11, even terrorism had been on the minds of at least a handful of stalwart preparedness experts – mostly in the military and in special governmental agencies (Benjamin & Simon, 2002; Stern, 2003; Clarke, 2004). The chapters in this volume survey the state of our understanding of the psychological response to terrorism and other exigent events. It is clear that much has been learned. At the same time, many questions remain. What are the best interventions post-event? How do we recognize those in most immediate need, or those who may be most susceptible, other than those with pre-existing psychopathology? (North et al. this volume). What sorts of pre-event messages are the most useful for preparing the community

Comments on differential cross section of phi-meson photoproduction at threshold

We show that the differential cross section d_sigma/d_t of gamma p --> \phi p reaction at the threshold is finite and its value is crucial to the mechanism of the phi meson photoproduction and for the models of phi-N interaction.Comment: 8 pages, 2 figure

Finite Temperature Spectral Densities of Momentum and R-Charge Correlators in N=4\N=4 Yang Mills Theory

We compute spectral densities of momentum and R-charge correlators in thermal $\N=4$ Yang Mills at strong coupling using the AdS/CFT correspondence. For $\omega \sim T$ and smaller, the spectral density differs markedly from perturbation theory; there is no kinetic theory peak. For large $\omega$, the spectral density oscillates around the zero-temperature result with an exponentially decreasing amplitude. Contrast this with QCD where the spectral density of the current-current correlator approaches the zero temperature result like $(T/\omega)^4$. Despite these marked differences with perturbation theory, in Euclidean space-time the correlators differ by only $\sim 10$ from the free result. The implications for Lattice QCD measurements of transport are discussed.Comment: 18 pages, 3 figure

Up The Street-March

https://digitalcommons.library.umaine.edu/mmb-ps/2035/thumbnail.jp

Arrival time distribution for a driven system containing quenched dichotomous disorder

We study the arrival time distribution of overdamped particles driven by a constant force in a piecewise linear random potential which generates the dichotomous random force. Our approach is based on the path integral representation of the probability density of the arrival time. We explicitly calculate the path integral for a special case of dichotomous disorder and use the corresponding characteristic function to derive prominent properties of the arrival time probability density. Specifically, we establish the scaling properties of the central moments, analyze the behavior of the probability density for short, long, and intermediate distances. In order to quantify the deviation of the arrival time distribution from a Gaussian shape, we evaluate the skewness and the kurtosis.Comment: 18 pages, 5 figure

Magnetovac Cylinder to Magnetovac Torus

A method for mapping known cylindrical magnetovac solutions to solutions in torus coordinates is developed. Identification of the cylinder ends changes topology from R1 x S1 to S1 x S1. An analytic Einstein-Maxwell solution for a toroidal magnetic field in tori is presented. The toroidal interior is matched to an asymptotically flat vacuum exterior, connected by an Israel boundary layer.Comment: to appear in Class. Quant. Gra

Two-dimensional shear modulus of a Langmuir foam

We deform a two-dimensional (2D) foam, created in a Langmuir monolayer, by applying a mechanical perturbation, and simultaneously image it by Brewster angle microscopy. We determine the foam stress tensor (through a determination of the 2D gas-liquid line tension, 2.35 $\pm$ 0.4 pJ$\cdot$m$^{-1}$) and the statistical strain tensor, by analyzing the images of the deformed structure. We deduce the 2D shear modulus of the foam, $\mu= 38 \pm 3 \mathrm{nN}\cdot \mathrm{m}^{-1}$. The foam effective rigidity is predicted to be $35 \pm 3 \mathrm {nN}\cdot \mathrm {m}^{- 1}$, which agrees with the value $37.5 \pm 0.8 \mathrm {nN}\cdot \mathrm {m}^{-1}$ obtained in an independent mechanical measurement.Comment: submitted May 12, 2003 ; resubmitted Sept 9, 200