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Introduction: Vehicular accidents at horizontal curves are over-represented compared to accidents that occur at tangent sections. Investigations have been conducted aimed at identifying the major causes that result in higher accident risk, both in terms of severity and rate, at curved road sections. Excessive or abrupt changes in speeding and improper vertical position are cited as major factors of lane departure, whereas other factors (either human or environmental) have also been documented. However, most research involves 4-wheel vehicles rather than other modes of transport that behave differently. More specifically, while motorcyclist fatalities occur more frequently than passenger vehicles, when accounting for vehicle distance traveled only a limited number of research studies address their behavior at curved road sections. Method: This paper presents the findings of field operational tests carried out by motorcyclists along two-lane rural roads with a wide range of horizontal curves using an instrumented motorcycle. Key objectives of the research included the conditions under which the motorcyclists differentiate their trajectory in regards to the direction of the horizontal curves, the correlation between the trajectory and the geometry of the road, and the impact of the lighting conditions on riders’ behavior. Results: The research showed that motorcyclists tend to ride closer to the centerline of the road, neglect the hazards associated with dim lighting conditions, and maintain constant speed in the left hand and the right-hand horizontal curves. 相似文献
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高斯轨迹烟云扩散模型在贵阳空气质量预报中的应用 总被引:4,自引:0,他引:4
选择在复杂地区应用较好的高斯轨迹烟云扩散模型,作为贵阳市空气质量预报的数学扩散模式,并利用贵阳市现有的污染源排放资料和气象资料,对贵阳市的大气污染物分布进行了模拟计算,经与实测结果比较表明:实测值与监测值基本一致,相关性较好。该模式可以作为贵阳市空气质量预报的数学扩散模式,对其他城市也具有一定的借鉴作用。 相似文献
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利用徐州2015年PM2.5和PM10逐小时质量浓度数据,分析了徐州颗粒物时空变化特征。同时基于HYSPLIT后向轨迹模式,结合GDAS气象数据和空气质量数据,利用轨迹聚类及潜在源分析法研究徐州不同季节气流轨迹对颗粒物浓度的影响及PM2.5和PM10的潜在来源。结果显示,2015年徐州环境空气中PM2.5和PM10的年均值为65和122μg/m3,分别超过国家《环境空气质量标准》(GB 3095—2012)二级标准限值86%和63%。各国控站点ρ(PM2.5)和ρ(PM10)月变化呈现一致的冬季高夏季低的"V"型变化特征,这与气象条件和气流轨迹特征季节性变化有关。秋冬季污染较高时期徐州主要受西北内陆性气团和较为稳定的气象条件影响,而春夏季来自较为干净的东部海洋性气团利于污染扩散。潜在源分析显示,山东、安徽、苏中南、浙西北等地区是影响徐州市PM2.5和PM10的主要潜在源区。各季节潜在源区分布范围有一定差异,冬季时潜在源区分布最广,并有明显向西北方向转移延伸的趋势。 相似文献
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大气环境质量预测模型研究 总被引:9,自引:0,他引:9
为适应青岛和贵阳地区地形和大气流场复杂的特点,吸收高斯烟云模式和烟团模式的优点,建立高斯轨迹烟云模式,模式同时考虑静风条件下的扩散。应用青岛和贵阳的实测数据对模式的性能进行检验,结果证明,该模式可适用于地形和流场复杂的地区。该模式是环境决策支持系统的一部分。 相似文献
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August Kaiser Helfried Scheifinger Wolfgang Spangl Andrea Weiss Stefan Gilge Wolfgang Fricke Ludwig Ries Danijel Cemas Brigita Jesenovec 《Atmospheric environment (Oxford, England : 1994)》2007,41(40):9273-9287
The Alpine stations Zugspitze, Hohenpeissenberg, Sonnblick, Jungfraujoch and Mt. Krvavec contribute to the Global Atmosphere Watch Programme (GAW) of the World Meteorological Organization (WMO). The aim of GAW is the surveillance of the large-scale chemical composition of the atmosphere. Thus, the detection of air pollutant transport from regional sources is of particular interest. In this paper, the origin of NOx (measured with a photo-converter), CO and O3 at the four Alpine GAW stations is studied by trajectory residence time statistics. Although these methods originated during the early 1980s, no comprehensive study of different atmospheric trace gases measured simultaneously at several background observatories in the Alps was conducted up to present.The main NOx source regions detected by the trajectory statistics are the northwest of Europe and the region covering East Germany, Czech Republic and southeast Poland, whereas the main CO source areas are the central, north eastern and eastern parts of Europe with some gradient from low to high latitudes. Subsiding air masses from west and southwest are relatively poor in NOx and CO.The statistics for ozone show strong seasonal effects. Near ground air masses are poor in ozone in winter but rich in ozone in summer. The main source for high ozone concentration in winter is air masses that subside from higher elevations, often enhanced by foehn effects at Hohenpeissenberg. During summer, the Mediterranean constitutes an important additional source for high ozone concentrations.Especially during winter, large differences between Hohenpeissenberg and the higher elevated stations are found. Hohenpeissenberg is frequently within the inversion, whereas the higher elevated stations are above the inversion.Jungfraujoch is the only station where the statistics detect an influence of air rich in CO and NOx from the Po Basin. 相似文献
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Vertical distribution of polycyclic aromatic hydrocarbons in atmospheric boundary layer of Beijing in winter 总被引:1,自引:0,他引:1
Shu Tao Yi Wang Shiming Wu Shuzheng Liu Han Dou Yanan Liu Chang Lang Fei Hu Baoshan Xing 《Atmospheric environment (Oxford, England : 1994)》2007,41(40):9594-9602
Air samples were collected using active samplers at various heights of 8, 15, 32, 47, 65, 80, 102, 120, 140, 160, 180, 200, 240, 280 and 320 m on a meteorological tower in an urban area of Beijing in two campaigns in winter 2006. Altitudinal distributions of polycyclic aromatic hydrocarbons (PAHs) in atmospheric boundary layer of Beijing in winter season were investigated. Meteorological conditions during the studied period were characterized by online measurements of four meteorological parameters as well as trajectory calculation. The mean total concentrations of 15 PAHs except naphthalene of gaseous and particulate phase were 667±450 and 331±144 ng m−3 in January and 61±19 and 29±6 ng m−3 in March, respectively. Domestic coal combustion and vehicle emission were the dominant PAH sources in winter. Although the composition profiles derived from the two campaigns were similar, the concentrations were different by one order of magnitude. The higher concentrations in January were partly caused by higher emission due to colder weather than March. Moreover, weak wind, passing through the city center before the sampling site, picked up more contaminants on the way and provided unfavorable dispersion condition in January. For both campaigns, PAH concentrations decreased with heights because of ground-level emission and unfavorable dispersion conditions in winter. The concentration ratio of PAHs in gas versus solid phases was temperature dependent and negatively correlated to their octanol–air partition coefficients. 相似文献
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G. Kurata G.R. Carmichael D.G. Streets T. Kitada Y. Tang J.-H. Woo N. Thongboonchoo 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):6977
Long-range transport of pollutants influenced by anthropogenic and natural emission sources in East Asia is investigated by using backward trajectory analysis along the NASA TRACE-P flight tracks and a numerical simulation with the three-dimensional chemical transport model (STEM-2k1). Observation-based regional distributions of trace gases are reconstructed using the observations obtained by measurements on board the DC-8 and P3-B aircrafts. Systematic features of the spatial distribution for each species are identified. It is found that the observed concentrations of CO and some NMHCs, and the ratios between these species, are highly associated with the source distribution features and their regional characteristics. Reconstructed fields of the observed and modeled ethane/CO and ethane/propane are found to reproduce well the estimated emission ratios in East Asia. We also investigated the time rate of change of the concentration of species and their ratio along the trajectory. From this analysis the propane/ethane and propane/acetylene ratios are shown to preserve their emission ratios during regional transport. However systematic differences in the propane vs. acetylene/CO relationships are found between the model and observation values. This analysis suggests that further efforts are needed to improve the estimates of biomass burning emissions in SE Asia. The results presented in this paper also suggest ways to further extend the capabilities to derive observation-based inventories. 相似文献
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辽宁中部地区沙尘来源及输送方式分析 总被引:1,自引:1,他引:0
以2010年春季3~5月间,辽宁省沈阳市、盘锦市、铁岭市3城市发生的3次沙尘天气为主要研究对象,利用安德森大流量采样器采集大气中悬浮颗粒物样品,分析不同沙尘天气状况下的颗粒物粒径组成,并结合气象状况采用后推气流轨迹模型,通过沙尘来临时3城市上空不同高度的后推气流轨迹,分析得出3城市沙尘的主要来源为蒙古高原与西伯利亚地区,输送方式以高空远距离输送为主,并伴随部分低空近距离传输和本地扬尘共同作用。 相似文献