Identifying risk factors for road traffic injuries can be considered one of the main priorities of transportation agencies. More than 12,000 fatal work zone crashes were reported between 2000 and 2013. Despite recent ...Identifying risk factors for road traffic injuries can be considered one of the main priorities of transportation agencies. More than 12,000 fatal work zone crashes were reported between 2000 and 2013. Despite recent efforts to improve work zone safety, the frequency and severity of work zone crashes are still a big concern for transportation agencies. Although many studies have been conducted on different work zone safety-related issues, there is a lack of studies that investigate the effect of adverse weather conditions on work zone crash severity. This paper utilizes probit–classification tree, a relatively recent and promising combination of machine learning technique and conventional parametric model, to identify factors affecting work zone crash severity in adverse weather conditions using 8 years of work zone weatherrelated crashes (2006–2013) in Washington State. The key strength of this technique lies in its capability to alleviate the shortcomings of both parametric and nonparametric models. The results showed that both presence of traffic control device and lighting conditions are significant interacting variables in the developed complementary crash severity model for work zone weather-related crashes. Therefore, transportation agencies and contractors need to invest more in lighting equipment and better traffic control strategies at work zones, specifically during adverse weather conditions.展开更多
Through typical sampling,the species,diameters at breast height (DBH) and growth status of street trees in Donghu Hi-tech Development Zone in Wuhan City were investigated;the characteristics and existing problems were...Through typical sampling,the species,diameters at breast height (DBH) and growth status of street trees in Donghu Hi-tech Development Zone in Wuhan City were investigated;the characteristics and existing problems were analyzed.Constructive suggestions were put forward to enrich urban street tree species and outstand the characteristics of local species,so as to provide references to the street tree planning in Donghu Hi-tech Development Zone in Wuhan City.展开更多
This study was designed to use LiDAR data to research tree heights in montane forest blocks of Kenya. It uses a completely randomised block design to asses if differences exist in forest heights: 1) among montane fore...This study was designed to use LiDAR data to research tree heights in montane forest blocks of Kenya. It uses a completely randomised block design to asses if differences exist in forest heights: 1) among montane forest blocks, 2) among Agro ecological zones (AEZ) within each forest block and 3) between similar AEZ in different forest blocks. Forest height data from the Geoscience Laser Altimeter System (GLAS) on the Ice Cloud and Land Elevation Satellite (ICE-SAT) for the period 2003-2009 was used for 2146 circular plots, of 0.2 - 0.25 ha in size. Results indicate that, tree height is largely influenced by Agro ecological conditions and the wetter zones have taller trees in the upper, middle and lower highlands. In the upper highland zones of limited human activity, tree heights did not vary among forest blocks. Variations in height among forest blocks and within forest blocks were exaggerated in regions of active human intervention.展开更多
[ Objective] The research aimed to study climatic zoning of tea tree cultivation in Hanzhong. [Method] Based on climate data at 11 meteorological observatories of Hanzhong during 1971 -2010, selecting annual average e...[ Objective] The research aimed to study climatic zoning of tea tree cultivation in Hanzhong. [Method] Based on climate data at 11 meteorological observatories of Hanzhong during 1971 -2010, selecting annual average extreme minimum temperature, annual average temperature, accumulative temperature ≥10 ℃ and annual rainfall as climatic zoning factors, regression model between zoning factors and geographic information was established, and comprehensive climatic zoning indicator of tea tree cultivation in Hanzhong was determined. [ Result] Tea tree cultivation in Hanzhong was divided into suitable, more suitable and unsuitable planting zones by using critical value of climatic zoning. [ Conclusion] The research could provide scientific basis for reasonable planning layout and sustainable development of tea tree in the whole city.展开更多
基金sponsored by the Federal Highway Administration(FHWA)in cooperation with the American Association of State Highway and Transportation Officials(AASHTO)
文摘Identifying risk factors for road traffic injuries can be considered one of the main priorities of transportation agencies. More than 12,000 fatal work zone crashes were reported between 2000 and 2013. Despite recent efforts to improve work zone safety, the frequency and severity of work zone crashes are still a big concern for transportation agencies. Although many studies have been conducted on different work zone safety-related issues, there is a lack of studies that investigate the effect of adverse weather conditions on work zone crash severity. This paper utilizes probit–classification tree, a relatively recent and promising combination of machine learning technique and conventional parametric model, to identify factors affecting work zone crash severity in adverse weather conditions using 8 years of work zone weatherrelated crashes (2006–2013) in Washington State. The key strength of this technique lies in its capability to alleviate the shortcomings of both parametric and nonparametric models. The results showed that both presence of traffic control device and lighting conditions are significant interacting variables in the developed complementary crash severity model for work zone weather-related crashes. Therefore, transportation agencies and contractors need to invest more in lighting equipment and better traffic control strategies at work zones, specifically during adverse weather conditions.
文摘Through typical sampling,the species,diameters at breast height (DBH) and growth status of street trees in Donghu Hi-tech Development Zone in Wuhan City were investigated;the characteristics and existing problems were analyzed.Constructive suggestions were put forward to enrich urban street tree species and outstand the characteristics of local species,so as to provide references to the street tree planning in Donghu Hi-tech Development Zone in Wuhan City.
文摘This study was designed to use LiDAR data to research tree heights in montane forest blocks of Kenya. It uses a completely randomised block design to asses if differences exist in forest heights: 1) among montane forest blocks, 2) among Agro ecological zones (AEZ) within each forest block and 3) between similar AEZ in different forest blocks. Forest height data from the Geoscience Laser Altimeter System (GLAS) on the Ice Cloud and Land Elevation Satellite (ICE-SAT) for the period 2003-2009 was used for 2146 circular plots, of 0.2 - 0.25 ha in size. Results indicate that, tree height is largely influenced by Agro ecological conditions and the wetter zones have taller trees in the upper, middle and lower highlands. In the upper highland zones of limited human activity, tree heights did not vary among forest blocks. Variations in height among forest blocks and within forest blocks were exaggerated in regions of active human intervention.
文摘[ Objective] The research aimed to study climatic zoning of tea tree cultivation in Hanzhong. [Method] Based on climate data at 11 meteorological observatories of Hanzhong during 1971 -2010, selecting annual average extreme minimum temperature, annual average temperature, accumulative temperature ≥10 ℃ and annual rainfall as climatic zoning factors, regression model between zoning factors and geographic information was established, and comprehensive climatic zoning indicator of tea tree cultivation in Hanzhong was determined. [ Result] Tea tree cultivation in Hanzhong was divided into suitable, more suitable and unsuitable planting zones by using critical value of climatic zoning. [ Conclusion] The research could provide scientific basis for reasonable planning layout and sustainable development of tea tree in the whole city.
