3,920 research outputs found

    Advanced thermal barrier coating systems

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    Current state-of-the-art thermal barrier coating (TBC) systems consist of partially stabilized zirconia coatings plasma sprayed over a MCrAlY bond coat. Although these systems have excellent thermal shock properties, they have shown themselves to be deficient for a number of diesel and aircraft applications. Two ternary ceramic plasma coatings are discussed with respect to their possible use in TBC systems. Zirconia-ceria-yttria (ZCY) coatings were developed with low thermal conductivities, good thermal shock resistance and improved resistance to vanadium containing environments, when compared to the baseline yttria stabilized zirconia (YSZ) coatings. In addition, dense zirconia-titania-yttria (ZTY) coatings were developed with particle erosion resistance exceeding conventional stabilized zirconia coatings. Both coatings were evaluated in conjunction with a NiCr-Al-Co-Y2O3 bond coat. Also, multilayer or hybrid coatings consisting of the bond coat with subsequent coatings of zirconia-ceria-yttria and zirconia-titania-yttria were evaluated. These coatings combine the enhanced performance characteristics of ZCY with the improved erosion resistance of ZTY coatings. Improvement in the erosion resistance of the TBC system should result in a more consistent delta T gradient during service. Economically, this may also translate into increased component life simply because the coating lasts longer

    Transfer molding of PMR-15 polyimide resin

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    Transfer molding is an economically viable method of producing small shapes of PMR-15 polyimide. It is shown that with regard to flexural, compressive, and tribological properties transfer-molded PMR-15 polyimide is essentially equivalent to PMR-15 polyimide produced by the more common method of compression molding. Minor variations in anisotropy are predictable effects of molding design and secondary finishing operations

    Sexual Predators: Mental Illness or Abnormality? A Psychiatrist\u27s Perspective

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    In this Symposium Article, the author discusses Washington’s Sexually Violent Predator Act, RCW 71.09.060, from a psychiatrist’s perspective

    Sexual Predators: Mental Illness or Abnormality? A Psychiatrist\u27s Perspective

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    In this Symposium Article, the author discusses Washington’s Sexually Violent Predator Act, RCW 71.09.060, from a psychiatrist’s perspective

    Preparation and Measurement Uncertainty in Quantum Mechanics

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    This thesis addresses two forms of quantum uncertainty. In part I, we focus on preparation uncertainty, an expression of the fact that there are sets of observables for which the induced probability distributions are not simultaneously sharp in any state. We exactly characterise the preparation uncertainty regions for several finite dimensional case studies, including a new derivation of the preparation uncertainty region for the Pauli observables of qubits, and two qutrit case studies which have not previously been addressed in the literature. We also consider the variance based preparation uncertainty for position and momentum observables for the well known “particle in a box” system. We see that the appropriate momentum observable is not given by the spectral measure of a self-adjoint operator, although the position observable is. The box system lacks the phase-space symmetry used to determine the free particle and particle on a ring systems so determining the box uncertainty region is rather more difficult than in these cases. We give upper and lower bounds on the boundary of the uncertainty region, and show that our upper bound is exact in an interval. In part II we turn our attention to measurement uncertainty, exploring the space of compatible joint approximations to incompatible target observables. We prove a general theorem, which shows that, for a broad class of figures of merit, the optimal compatible approximations to covariant targets are themselves covariant. This substantially simplifies the problem of determining measurement uncertainty regions for covariant observables, since the space of covariant compatible approximations is smaller than the space of all compatible approximations. We employ this theorem to derive measurement uncertainty regions for three mutually orthogonal Pauli observables, and for the quantum Fourier pair acting in any finite dimension

    Improving the Impact of Market Reform on Agricultural Productivity in Africa: How Institutional Design Makes a Difference

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    Improving the Impact of Market Reform on Agricultural Productivity in Africa: How Institutional Design Makes a Difference Abstract: This paper reviews the emerging empirical record of agricultural marketing policy reform and agricultural productivity, drawing from research on food access and agricultural productivity supported by USAID’s Africa Bureau on seven countries in West, Eastern, and Southern Africa. We also examine key factors constraining past and future performance of the food systems in these countries. The paper concludes by identifying a set of policy issues for further consideration that would help provide the investment incentives to promote productivity growth for the millions of low-input semi-subsistence rural households in the region.food security, food policy, market reform, Agricultural and Food Policy, Marketing, Productivity Analysis, Downloads June 2008 - July 2009: 40, Q13,

    Sampling Problems and Interpretation of Chemical Analysis of Mineral Springs Used by Wildlife

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    Mineral-rich springs used by wildlife were studied in order to develop an appropriate sampling technique. The mineral content of the water varied spatially within a lick, apparently because of contamination by nonlick water and animal urine. The spring source usually could be located with a conductivity meter. Samples contaminated by animal urine could be recognized by their high N content and usually by their color. The distinctive chemical composition of licks is best appreciated by comparing filtered samples of lick water with nonlick water collected nearby. Field filtration was necessary when samples were preserved with acid for trace-metal analysis. Soil samples from lick and nonlick sites revealed of the properties of the spring water, but not as well as water analysis. High levels of Na were found the spring water of all Ontario licks sampled. Many conflicting results among other studies may be attributable to inappropriate sampling

    Sampling Problems and Interpretation of Chemical Analysis of Mineral Springs Used by Wildlife

    Get PDF
    Mineral-rich springs used by wildlife were studied in order to develop an appropriate sampling technique. The mineral content of the water varied spatially within a lick, apparently because of contamination by nonlick water and animal urine. The spring source usually could be located with a conductivity meter. Samples contaminated by animal urine could be recognized by their high N content and usually by their color. The distinctive chemical composition of licks is best appreciated by comparing filtered samples of lick water with nonlick water collected nearby. Field filtration was necessary when samples were preserved with acid for trace-metal analysis. Soil samples from lick and nonlick sites revealed of the properties of the spring water, but not as well as water analysis. High levels of Na were found the spring water of all Ontario licks sampled. Many conflicting results among other studies may be attributable to inappropriate sampling

    A SYSTEM FOR THE EVALUATION OF ON-WATER STROKE FORCE DEVELOPMENT DURING CANOE AND KAYAK EVENTS

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    Sport practitioners, including coaches and athletes of a wide variety of sport disciplines, are becoming more and more aware of the value of recording and analysing the real time data correlates of the force output of the athlete under competitive conditions. In no other comparable onwater sport is the relationship between absolute force development and the manner of its production and application more critical to the final outcome of the event than in flatwater canoe and kayak, particularly in multiple athlete events (Plagenhoef, 1979; Mann and Kearney, 1980)
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