66,299 research outputs found

    Wet atmospheric generation apparatus

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    The invention described relates to an apparatus for providing a selectively humidified gas to a camera canister containing cameras and film used in space. A source of pressurized gas (leak test gas or motive gas) is selected by a valve, regulated to a desired pressure by a regulator, and routed through an ejector (venturi device). A regulated source of water vapor in the form of steam from a heated reservoir is coupled to a low pressure region of the ejector which mixes with high velocity gas flow through the ejector. This mixture is sampled by a dew point sensor to obtain dew point thereof (ratio of water vapor to gas) and the apparatus adjusted by varying gas pressure or water vapor to provide a mixture at a connector having selected humidity content

    Interoperability between Multimedia Collections for Content and Metadata-Based Searching

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    Artiste is a European project developing a cross-collection search system for art galleries and museums. It combines image content retrieval with text based retrieval and uses RDF mappings in order to integrate diverse databases. The test sites of the Louvre, Victoria and Albert Museum, Uffizi Gallery and National Gallery London provide their own database schema for existing metadata, avoiding the need for migration to a common schema. The system will accept a query based on one museum’s fields and convert them, through an RDF mapping into a form suitable for querying the other collections. The nature of some of the image processing algorithms means that the system can be slow for some computations, so the system is session-based to allow the user to return to the results later. The system has been built within a J2EE/EJB framework, using the Jboss Enterprise Application Server

    NONPARAMETRIC ESTIMATION OF MULTIPRODUCT AND PRODUCT-SPECIFIC ECONOMIES OF SCALE

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    Numerous studies have utilized nonparametric estimation of production efficiency but no such study focuses on multiproduct or product-specific economies of scale. A mathematical program is specified to nonparametrically estimate these measures for crops and livestock for Kansas farms. Results show that many farms would realize benefits from expansion.Industrial Organization,

    Hole polaron formation and migration in olivine phosphate materials

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    By combining first principles calculations and experimental XPS measurements, we investigate the electronic structure of potential Li-ion battery cathode materials LiMPO4 (M=Mn,Fe,Co,Ni) to uncover the underlying mechanisms that determine small hole polaron formation and migration. We show that small hole polaron formation depends on features in the electronic structure near the valence-band maximum and that, calculationally, these features depend on the methodology chosen for dealing with the correlated nature of the transition-metal d-derived states in these systems. Comparison with experiment reveals that a hybrid functional approach is superior to GGA+U in correctly reproducing the XPS spectra. Using this approach we find that LiNiPO4 cannot support small hole polarons, but that the other three compounds can. The migration barrier is determined mainly by the strong or weak bonding nature of the states at the top of the valence band, resulting in a substantially higher barrier for LiMnPO4 than for LiCoPO4 or LiFePO4

    Critical evaluation of the computational methods used in the forced polymer translocation

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    In forced polymer translocation, the average translocation time, τ\tau, scales with respect to pore force, ff, and polymer length, NN, as τf1Nβ\tau \sim f^{-1} N^{\beta}. We demonstrate that an artifact in Metropolis Monte Carlo method resulting in breakage of the force scaling with large ff may be responsible for some of the controversies between different computationally obtained results and also between computational and experimental results. Using Langevin dynamics simulations we show that the scaling exponent β1+ν\beta \le 1 + \nu is not universal, but depends on ff. Moreover, we show that forced translocation can be described by a relatively simple force balance argument and β\beta to arise solely from the initial polymer configuration

    MODELING CHANGES IN THE U.S. DEMAND FOR CROP INSURANCE DURING THE 1990S

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    The crop insurance purchase decision for a group of Kansas farmers is analyzed using data from 1990sa period that experienced many changes in the federal crop insurance program. Farm-level data are used. Results indicate a reduction in the elasticity of the demand for crop insurance with respect to premium rates by the end of the decade. This corresponded with a considerable increase in government subsidies by the end of the 1990s. This may also reflect the attractiveness of new revenue insurance products that may have made producers less sensitive to premium changes.Risk and Uncertainty,

    Interfacial friction between semiflexible polymers and crystalline surfaces

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    The results obtained from molecular dynamics simulations of the friction at an interface between polymer melts and weakly attractive crystalline surfaces are reported. We consider a coarse-grained bead-spring model of linear chains with adjustable intrinsic stiffness. The structure and relaxation dynamics of polymer chains near interfaces are quantified by the radius of gyration and decay of the time autocorrelation function of the first normal mode. We found that the friction coefficient at small slip velocities exhibits a distinct maximum which appears due to shear-induced alignment of semiflexible chain segments in contact with solid walls. At large slip velocities the decay of the friction coefficient is independent of the chain stiffness. The data for the friction coefficient and shear viscosity are used to elucidate main trends in the nonlinear shear rate dependence of the slip length. The influence of chain stiffness on the relationship between the friction coefficient and the structure factor in the first fluid layer is discussed.Comment: 31 pages, 12 figure

    Did U.S. Bank Supervisors Get Tougher During the Credit Crunch? Did They Get Easier During the Banking Boom? Did It Matter to Bank Lending?

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    We test three hypotheses regarding changes in supervisory toughness' and their effects on bank lending. The data provide modest support for all three hypotheses that there was an increase in toughness during the credit crunch period (1989-1992), that there was a decline in toughness during the boom period (1993-1998), and that changes in toughness, if they occurred, affected bank lending. However, all of the measured effects are small, with 1% or less of loans receiving harsher or easier classification, about 3% of banks receiving better or worse CAMEL ratings, and bank lending being changed by 1% or less of assets.

    Farmers' Crop Acreage Decisions in the Presence of Credit Constraints: Do Decoupled Payments Matter?

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    While in theory decoupled payments do not distort production decisions, in practice there are several potential coupling mechanisms for these payments. We use farm-level data from Kansas to revisit the issue of how (de)coupled are these supposedly “decoupled” payments by focusing on how they may impact production through credit constraints. In particular, we study how production effects may have differed across farmers with varying levels of debt pressure. Our empirical approach exploits the fact that we can observe the same farm over time (and so can account for the effects of time-constant omitted variables) to study how these payments affected total crop acres, owned acres, and the decisions to plant corn, sorghum, soybeans and wheat. Like previous studies, we find small production effects. Nonetheless our results suggest decoupled payments have potentially distortionary effects on production.decoupled payments, credit constraints, Agricultural Finance, Q17, Q18,

    Activated dynamics and effective temperature in a steady state sheared glass

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    We conduct nonequilibrium molecular dynamics simulations to measure the shear stress, the average inherent structure energy, and the effective temperature TeffT_{eff} of a sheared model glass as a function of bath temperature TT and shear strain rate. For TT above the glass transition temperature T0T_0, the rheology approaches a Newtonian limit and TeffT_{eff} approaches TT as the strain rate approaches zero, while for T<T0T<T_0, the shear stress approaches a yield stress and TeffT_{eff} approaches a limiting value near T0T_0. In the shear-dominated regime at high TT, high strain rate or at low TT, we find that the shear stress and the average inherent structure energy each collapse onto a single curve as a function of TeffT_{eff}. This indicates that TeffT_{eff} is controlling behavior in this regime.Comment: 4 pages, 2 figures. Revised to include additional data. Inherent structure energy results were included, and much of the shear transformation zone discussion was remove
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