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High Charge‐Carrier Mobility of 2.5 cm2 V−1 s−1 from a Water‐Borne Colloid of a Polymeric Semiconductor via Smart Surfactant Engineering 下载免费PDF全文
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Walking is a popular form of physical activity associated with clear health benefits. Promoting safe walking for pedestrians requires evaluating the risk of pedestrian–motor vehicle collisions at specific roadway locations in order to identify where road improvements and other interventions may be needed. The objective of this analysis was to estimate the risk of pedestrian collisions at intersections and mid-blocks in Seattle, WA. The study used 2007–2013 pedestrian–motor vehicle collision data from police reports and detailed characteristics of the microenvironment and macroenvironment at intersection and mid-block locations. The primary outcome was the number of pedestrian–motor vehicle collisions over time at each location (incident rate ratio [IRR] and 95% confidence interval [95% CI]). Multilevel mixed effects Poisson models accounted for correlation within and between locations and census blocks over time. Analysis accounted for pedestrian and vehicle activity (e.g., residential density and road classification). In the final multivariable model, intersections with 4 segments or 5 or more segments had higher pedestrian collision rates compared to mid-blocks. Non-residential roads had significantly higher rates than residential roads, with principal arterials having the highest collision rate. The pedestrian collision rate was higher by 9% per 10 feet of street width. Locations with traffic signals had twice the collision rate of locations without a signal and those with marked crosswalks also had a higher rate. Locations with a marked crosswalk also had higher risk of collision. Locations with a one-way road or those with signs encouraging motorists to cede the right-of-way to pedestrians had fewer pedestrian collisions. Collision rates were higher in locations that encourage greater pedestrian activity (more bus use, more fast food restaurants, higher employment, residential, and population densities). Locations with higher intersection density had a lower rate of collisions as did those in areas with higher residential property values. The novel spatiotemporal approach used that integrates road/crossing characteristics with surrounding neighborhood characteristics should help city agencies better identify high-risk locations for further study and analysis. Improving roads and making them safer for pedestrians achieves the public health goals of reducing pedestrian collisions and promoting physical activity. 相似文献
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随着军队信息化建设的加快,复杂电磁环境无疑成为现代信息化战争的基本特征,“制电磁权”将成为作战双方的争夺“制高点”。依据电磁环境的组成和特点,提出了一种基于半实物仿真仿真平台的复杂电磁环境评估方法和分级标准,并通过实例对该方法进行了计算验证,结果表明该方法较好地反映了实验室条件下电磁环境的复杂性,可有效支撑电子装备研究。 相似文献
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腐蚀环境对预腐蚀铝合金腐蚀疲劳性能的影响 总被引:8,自引:0,他引:8
采用不同环境下的轴向加载疲劳性能测试方法,研究了不同环境对预腐蚀7XXX铝合金腐蚀疲劳性能的影响.结果表明:腐蚀环境对其疲劳寿命的影响从重到轻依次是:油箱积水、盐水、潮湿空气和实验室空气.当应力比R为0.5和0.06时,潮湿空气下的疲劳寿命比实验室空气下的略低,降低的幅度随着应力的降低而增大;在低应力水平区盐水和油箱积水环境对疲劳寿命的影响基本相同.当应力比R为-1时,盐水下的疲劳寿命总是略低于油箱积水环境下的疲劳寿命;潮湿空气相比实验室空气下的疲劳寿命随着应力的降低,降低的幅度比应力比为0.5和0.06时要略大. 相似文献
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