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More than 200 people have died in automobiles that have encountered flooded roadways in Texas from 1950 to 2004. This study examines the geographical processes that create flood hazards associated with automobile travel to discern the most important factors in their genesis. A database of drowning cases caused by motorists' interactions with flooded roadways in Texas was compiled for the study period. We examine the circumstances and spatial patterns of these events by addressing the following questions: where have motorists drowned? How did rates and spatial patterns of accidents change over the study period? To the extent that we can determine, what were the characteristics of the roads, the drivers, and the landscapes when and where deaths occurred? What factors appear to explain the temporal and spatial distributions of hazard? We conclude that roadway familiarity might have emboldened drivers to attempt to surmount water rushing across a road, that time of day was clearly an important characteristic of the accidents, and that roadway characteristics and sex and age of the drivers seem not to be key contributing factors. The most important factors, however, are associated with growth: increases in population and increased automobile registrations drive the propensity for increased automobile-flood hazards. 相似文献
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Numerous departures from ideal relationships are revealed by Monte Carlo simulations of widely accepted binomial coefficients. For example, simulations incorporating varying levels of matrix sparseness (presence of zeros indicating lack of data) and computation of expected values reveal that not only are all common coefficients influenced by zero data, but also that some coefficients do not discriminate between sparse or dense matrices (few zero data). Such coefficients computationally merge mutually shared and mutually absent information and do not exploit all the information incorporated within the standard 2 × 2 contingency table; therefore, the commonly used formulae for such coefficients are more complicated than the actual range of values produced. Other coefficients do differentiate between mutual presences and absences; however, a number of these coefficients do not demonstrate a linear relationship to matrix sparseness. Finally, simulations using nonrandom matrices with known degrees of row-by-row similarities signify that several coefficients either do not display a reasonable range of values or are nonlinear with respect to known relationships within the data. Analyses with nonrandom matrices yield clues as to the utility of certain coefficients for specific applications. For example, coefficients such as Jaccard, Dice, and Baroni-Urbani and Buser are useful if correction of sparseness is desired, whereas the Russell-Rao coefficient is useful when sparseness correction is not desired. 相似文献
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A. Mautner H. A. Maples T. Kobkeatthawin V. Kokol Z. Karim K. Li A. Bismarck 《International Journal of Environmental Science and Technology》2016,13(8):1861-1872
Copper is a major problem in industrial wastewater streams, seriously affecting the quality of potential drinking water. Several approaches, including continuous membrane processes or batch-wise application of adsorbents, are in use to tackle this problem. Unfortunately, these processes suffer from their particular drawbacks, such as low permeance or disposal of saturated adsorbents. However, a combination of these processes could constitute a step towards a more efficient copper removal solution. Here, we present a nanopaper ion-exchanger prepared from cellulose nanofibrils produced from fibre sludge, a paper industry waste stream, for the efficient, continuous removal of copper from aqueous solutions. This nanopaper ion-exchanger comprises phosphorylated cellulose nanofibrils that were processed into nanopapers by papermaking. The performance of these phosphorylated nanopaper membranes was determined with respect to their rejection of copper and permeance. It was shown that this new type of nanopaper is capable of rejecting copper ions during a filtration process by adsorption. Results suggest that functional groups on the surface of the nanopapers contribute to the adsorption of copper ions to a greater extent than phosphate groups within the bulk of the nanopaper. Moreover, we demonstrated that those nanopaper ion-exchangers could be regenerated and reused and that in the presence of calcium ions, the adsorption capacity for copper was only slightly reduced. 相似文献
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