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761.
An analysis of motorcycle injury and vehicle damage severity using ordered probit models 总被引:7,自引:0,他引:7
Problem: Motorcycles constitute about 19% of all motorized vehicles in Singapore and are generally overrepresented in traffic accidents, accounting for 40% of total fatalities. Method: In this paper, an ordered probit model is used to examine factors that affect the injury severity of motorcycle accidents and the severity of damage to the vehicle for those crashes. Nine years of motorcycle accident data were obtained for Singapore through police reports. These data included categorical assessments of the severity of accidents based on three levels. Damage severity to the vehicle was also assessed and categorized into four levels. Categorical data of this type are best analyzed using ordered probit models because they require no assumptions regarding the ordinality of the dependent variable, which in this case is the severity score. Various models are examined to determine what factors are related to increased injury and damage severity of motorcycle accidents. Results: Factors found to lead to increases in the probability of severe injuries include the motorcyclist having non-Singaporean nationality, increased engine capacity, headlight not turned on during daytime, collisions with pedestrians and stationary objects, driving during early morning hours, having a pillion passenger, and when the motorcyclist is determined to be at fault for the accident. Factors leading to increased probability of vehicle damage include some similar factors but also show some differences, such as less damage associated with pedestrian collisions and with female drivers. In addition, it was also found that both injury severity and vehicle damage severity levels are decreasing over time. 相似文献
762.
Three mathematical models, the runoff curve number equation, the universal soil loss equation, and the mass response functions,
were evaluated for predicting nonpoint source nutrient loading from agricultural watersheds of the Mediterranean region. These
methodologies were applied to a catchment, the gulf of Gera Basin, that is a typical terrestrial ecosystem of the islands
of the Aegean archipelago. The calibration of the model parameters was based on data from experimental plots from which edge-of-field
losses of sediment, water runoff, and nutrients were measured. Special emphasis was given to the transport of dissolved and
solid-phase nutrients from their sources in the farmers' fields to the outlet of the watershed in order to estimate respective
attenuation rates. It was found that nonpoint nutrient loading due to surface losses was high during winter, the contribution
being between 50% and 80% of the total annual nutrient losses from the terrestrial ecosystem. The good fit between simulated
and experimental data supports the view that these modeling procedures should be considered as reliable and effective methodological
tools in Mediterranean areas for evaluating potential control measures, such as management practices for soil and water conservation
and changes in land uses, aimed at diminishing soil loss and nutrient delivery to surface waters. Furthermore, the modifications
of the general mathematical formulations and the experimental values of the model parameters provided by the study can be
used in further application of these methodologies in watersheds with similar characteristics. 相似文献
763.
764.
This paper compares predictions of the foodchain model SPADE with experimental data for the transfer of (134)Cs and (85)Sr to strawberry plants following acute foliar and soil contamination. The transfer pathways considered in this exercise included direct deposition to fruit, leaf-to-fruit, soil-to-leaf and soil-to-fruit transfers. Following foliar contamination, the difference between predicted and measured radionuclide activity values varied between a factor of 0.5-10 for fruit and 4.5-7 for leaf. Following soil contamination, the difference between predicted and measured values varied between a factor of 3-74 for fruit and 32-44 for leaf. In all cases the difference between measured and predicted values was smaller for (85)Sr than (134)Cs. Measured and predicted activities were higher for leaf than fruit. Both measured and predicted (134)Cs concentrations in fruit and leaf are higher when deposition occurs at ripening than at anthesis. These results confirm the need for more data on fruit, even for Cs and Sr, to support models in predicting the transfer of radionuclides to fruit crops. Ongoing research projects funded by the UK Food Standards Agency aim to provide some data on radionuclide transfer to herbaceous, shrub and tree fruits, which will help improve radiological assessment models in order to provide better protection for consumers. 相似文献
765.
青藏铁路列车运行控制系统的安全性分析 总被引:4,自引:4,他引:0
分析了青藏铁路中多种不利因素对轨道电路参数的影响 ;提出了在青藏铁路不宜采用现行基于轨道电路的列车运行控制系统 ,而应选择基于通信的列车运行控制系统的理由 ;给出了系统的基本结构及提高系统可靠性的措施 ;与此同时 ,就人们关心的无线传输列车控制数据的可靠性和安全性难题 ,通过建立马尔可夫模型的方法进行了分析 相似文献
766.
在实地调查和与专家访谈的基础上设计函调问卷,通过对函调问卷的综合分析,构建模糊评价模型,对西递旅游与社区经济互动持续发展水平做出评判。结果表明,西递旅游与社区经济处在基本可持续发展阶段,但也存在着一些制约旅游与社区经济互动持续发展的因素。在此基础上,提出促进西递旅游与社区经济互动持续发展的建议和措施。 相似文献
767.
768.
国内外油田含油污泥处理技术 总被引:9,自引:1,他引:9
通过对国内外各种含油污泥处理工艺技术的调查分析和对比,提出了适合国内实际的含油污泥处理技术方案。以离心分离技术为核心,辅之以调质、倾析等多种预处理技术和高温裂解、生物处理等后续处理技术的污泥综合处理工艺,适于我国现阶段的含油污泥处理。 相似文献
769.
770.
可拓法评估煤矿瓦斯爆炸易发性 总被引:3,自引:0,他引:3
为了量化煤矿瓦斯爆炸的可能性,并为防治瓦斯爆炸提供量化指标,借鉴可拓学原理,对煤矿瓦斯爆炸易发性进行预评估。首先,详细阐述可拓学评估原理;接着,为了验证煤矿瓦斯爆炸易发性可拓评估的可行性,结合某一煤矿实例,比选煤矿瓦斯爆炸易发性的评价指标,并确定煤矿瓦斯爆炸易发性的分类标准,构建煤矿瓦斯爆炸易发性评估的经典域、节域和物元;然后,为了避免确定指标权重的人为主观因素的影响,提出用简单关联函数确定指标权重;最后,计算煤矿瓦斯爆炸易发性的关联函数值和关联度,确定瓦斯爆炸易发性的等级及其变量特征值。经计算,煤矿爆炸易发性的可拓评估结果为"很小"等级。同时,为了验证可拓评估结果的合理性,将其与模糊评估进行比较,两者所得评估结果相一致。从而表明:将可拓学应用于煤矿瓦斯爆炸易发性评估是合理可行的。 相似文献