14,032 research outputs found

    Seismic Response of Wind Turbines on Caisson-Type Foundations in Soft Clay

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    Selected aspects of lunar mare geology from Apollo orbital photography

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    Crater size-frequency distributions were studied (100-500 m) and are shown to provide significant integrated information concerning mare surface ages, subsurface stratigraphy, and surficial geology. Equilibrium cratering is discussed gradually reducing the relative numbers of craters smaller than 300-400 m in diameter as surfaces age and regolith thickens. Results for surface ages are in good agreement with other published crater ages. The existing correlations of large ring structures among various circular mare basins are shown to be based on criteria that are inconsistent and nonstandardized. A means of comparing equivalent ring structures in the different maria is proposed which takes into account the important characteristics of young unflooded basins (Orientale) as well as the progressive development of tectonic and volcanic features within the older flooded maria. Specific geologic aspects of several of the lunar maria are discussed and especially Mare Smythii, because of its great age and significantly different surface morphology. Lunar photographs and maps are shown

    Calculating partial expected value of perfect information via Monte Carlo sampling algorithms

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    Partial expected value of perfect information (EVPI) calculations can quantify the value of learning about particular subsets of uncertain parameters in decision models. Published case studies have used different computational approaches. This article examines the computation of partial EVPI estimates via Monte Carlo sampling algorithms. The mathematical definition shows 2 nested expectations, which must be evaluated separately because of the need to compute a maximum between them. A generalized Monte Carlo sampling algorithm uses nested simulation with an outer loop to sample parameters of interest and, conditional upon these, an inner loop to sample remaining uncertain parameters. Alternative computation methods and shortcut algorithms are discussed and mathematical conditions for their use considered. Maxima of Monte Carlo estimates of expectations are biased upward, and the authors show that the use of small samples results in biased EVPI estimates. Three case studies illustrate 1) the bias due to maximization and also the inaccuracy of shortcut algorithms 2) when correlated variables are present and 3) when there is nonlinearity in net benefit functions. If relatively small correlation or nonlinearity is present, then the shortcut algorithm can be substantially inaccurate. Empirical investigation of the numbers of Monte Carlo samples suggests that fewer samples on the outer level and more on the inner level could be efficient and that relatively small numbers of samples can sometimes be used. Several remaining areas for methodological development are set out. A wider application of partial EVPI is recommended both for greater understanding of decision uncertainty and for analyzing research priorities

    Improving fertiliser management: redefining the relationship between soil tests and crop responses for wheat in WA

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    Most soils in Western Australia (WA) are highly weathered with very low levels of phosphorus. WA soils initially contained adequate indigenous soil potassium for cropping but removal of potassium over time in harvested grain has gradually resulted in the some soils becoming potassium-deficient for grain production. Fertiliser costs represent a significant part of the variable costs of growing crops in WA. Chen et al. (2009) identified the need for updated soil test interpretations due to substantial changes in farming systems, fertiliser practices and crop yield potential. The aims of this study were (1) to compile experimental data containing the standard soil test measurements and observed wheat crop yield responses for both nil and fertilised treatments across different soil types and seasons from published or unpublished sources, and (2) to critically analyse soil test-crop response relationships to derive better critical soil test values in soils and environments suitable for wheat grain production in WA

    Spatial distribution of the common loon (Gavia immer) in New Hampshire

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    The Common Loon (Gavia immer) is located in many portions of North America. By the early 1970\u27s the Common Loon population in New Hampshire had experienced a dramatic decline in historic numbers. In 1975, the Audubon Society of New Hampshire recognized this problem and established the Loon Preservation Committee (LPC). The intent was to collect information regarding the presence or absence of loons and loon productivity, and, educate the public regarding loon ecology and preservation. This dissertation represents the work completed to fulfill the requirements for the Doctor of Philosophy degree in Natural Resources Management at the University of New Hampshire. The research concentrated on analyzing georeferenced loon management data collected by LPC from 1980--2002 and understanding loon habitat occupancy. Specific objectives of this study were to: (1) investigate the colonization patterns of the Common Loon in New Hampshire, (2) identify and prioritize potential loon habitat in New Hampshire, and (3) develop and implement methods to be used by the Loon Preservation Committee for current and future loon management. Methods are described for converting and analyzing a 29-year historical database maintained by the Loon Preservation Committee located in Moultonborough, New Hampshire. Through this effort, techniques and results for: analog to digital data conversion, automating new data collection, and spatial analysis are discussed. Lake perimeter, lake depth, distance to lakes with and without loons, and lake elevation were identified as significant factors for determining loon habitat occupancy in New Hampshire. The results of implementing a GIS-enabled loon habitat occupancy model are presented

    Cooldown time for simple cryogenic pipelines

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    Cooldown time for simple cryogenic pipeline
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