Compared with roundabouts the main advantages of turbo-roundabouts are the reduction in the number of potential conflicting points and the lower speed of vehicles passing through the intersection, they both can improv...Compared with roundabouts the main advantages of turbo-roundabouts are the reduction in the number of potential conflicting points and the lower speed of vehicles passing through the intersection, they both can improve safety conditions at the .junction. Moreover, the physical delimitation among lanes limits the side-by-side accident risk. These aspects make turbo-roundabouts more appropriate than roundabouts when a higher level of safety has to be guaranteed, particularly in presence of relevant pedestrian and two-wheels traffic volumes. The present paper has three main objectives： （1） to discuss general design criteria and functional principles of turbo roundabouts, （2） to give the geometric design principles of the central island and circulating lanes and （3） to present three case studies from real world concerning the conversion of existing roundabouts into turbo roundabouts.展开更多
This article research the food quality standards covered global and international regulations on food safety and quality, and public and private standards. The effect of global character of food safety and quality sta...This article research the food quality standards covered global and international regulations on food safety and quality, and public and private standards. The effect of global character of food safety and quality standardization shows that the important effect is increasing marginal costs of certification and accreditation, which puts pressure on export company profits in different countries. Main conclusions yield insights into the key following points： Increased food safety has been associated with higher income. Consumers and governments can afford to focus more on reducing food-borne safety risks once basic quantity needs for foods have been met or are in the process of being met. This suggests that policies focused on increasing income are the surest path to improving food safety in all countries. Food safety regulations should be designed to meet the food safety demands of consumers in rich countries and, at the same time, further the interests of both consumers and producers in poor countries.展开更多
Zhangjiakou region is situated in an agro-pastoral ecotone with a fragile ecosystem. While it has limited surface water resources available and serious groundwater over-exploitation, the city is located in the water c...Zhangjiakou region is situated in an agro-pastoral ecotone with a fragile ecosystem. While it has limited surface water resources available and serious groundwater over-exploitation, the city is located in the water conservation zone for the Beijing-Tianjin-Hebei coordinated development area, so its water security is crucial for the entire Beijing-Tianjin-Hebei region. Therefore, it is of vital significance to determine the zoning management of water resources and decision-making according to the magnitude of water resource security risks. This study built an indicator system for water security risk assessment in line with the principles of scientific validity, comparability, operability, and data availability, and this system gives weights to these indicators using the AHP approach. County-level multi-source data for the study area, based on water resource zones, were collected by using mathematical statistics and 3 S technology. With normalized data and a weighting method the water security risks were calculated. The results showed large spatial variations of water security risks in Zhangjiakou on the scales of geomorphic and administrative units as well as river basins. High-risk areas are extensive in the Bashang Plateau, and extremely high risk values are found in the Baxia areas. On the watershed scale, high-risk areas are mainly distributed in the inland river basins and the Yongding River basin. The risk values of the Luanhe River, Chaobai River and Daqing River basins in the Zhangjiakou region tend to decrease from north to south. For the northern and western areas of the Bashang Plateau, the factor of "vulnerability of the disaster-prone environment" contributes the most to the water security risk level. Agricultural water use constrains industrial and ecological water use, but in the context of inadequate water resource endowments, the urban population concentration and industrial development are the main causes of water shortages and water pollution so they contribute more to water security risks. This study of the spatial variation of water security risks in Zhangjiakou can provide an important scientific reference for zone-based management and decision-making for reducing the water security risks in the farming-pastoral ecotone.展开更多
文摘Compared with roundabouts the main advantages of turbo-roundabouts are the reduction in the number of potential conflicting points and the lower speed of vehicles passing through the intersection, they both can improve safety conditions at the .junction. Moreover, the physical delimitation among lanes limits the side-by-side accident risk. These aspects make turbo-roundabouts more appropriate than roundabouts when a higher level of safety has to be guaranteed, particularly in presence of relevant pedestrian and two-wheels traffic volumes. The present paper has three main objectives： （1） to discuss general design criteria and functional principles of turbo roundabouts, （2） to give the geometric design principles of the central island and circulating lanes and （3） to present three case studies from real world concerning the conversion of existing roundabouts into turbo roundabouts.
文摘This article research the food quality standards covered global and international regulations on food safety and quality, and public and private standards. The effect of global character of food safety and quality standardization shows that the important effect is increasing marginal costs of certification and accreditation, which puts pressure on export company profits in different countries. Main conclusions yield insights into the key following points： Increased food safety has been associated with higher income. Consumers and governments can afford to focus more on reducing food-borne safety risks once basic quantity needs for foods have been met or are in the process of being met. This suggests that policies focused on increasing income are the surest path to improving food safety in all countries. Food safety regulations should be designed to meet the food safety demands of consumers in rich countries and, at the same time, further the interests of both consumers and producers in poor countries.
基金The National Major Science and Technology Program for Water Pollution Control and Treatment (2017ZX07101001)Guizhou Normal University Doctoral Funds (GZNUD20178, GZNUD20179)Science and Technology Program of Guizhou Province (20191218, 20191222, 20201Z031)。
文摘Zhangjiakou region is situated in an agro-pastoral ecotone with a fragile ecosystem. While it has limited surface water resources available and serious groundwater over-exploitation, the city is located in the water conservation zone for the Beijing-Tianjin-Hebei coordinated development area, so its water security is crucial for the entire Beijing-Tianjin-Hebei region. Therefore, it is of vital significance to determine the zoning management of water resources and decision-making according to the magnitude of water resource security risks. This study built an indicator system for water security risk assessment in line with the principles of scientific validity, comparability, operability, and data availability, and this system gives weights to these indicators using the AHP approach. County-level multi-source data for the study area, based on water resource zones, were collected by using mathematical statistics and 3 S technology. With normalized data and a weighting method the water security risks were calculated. The results showed large spatial variations of water security risks in Zhangjiakou on the scales of geomorphic and administrative units as well as river basins. High-risk areas are extensive in the Bashang Plateau, and extremely high risk values are found in the Baxia areas. On the watershed scale, high-risk areas are mainly distributed in the inland river basins and the Yongding River basin. The risk values of the Luanhe River, Chaobai River and Daqing River basins in the Zhangjiakou region tend to decrease from north to south. For the northern and western areas of the Bashang Plateau, the factor of "vulnerability of the disaster-prone environment" contributes the most to the water security risk level. Agricultural water use constrains industrial and ecological water use, but in the context of inadequate water resource endowments, the urban population concentration and industrial development are the main causes of water shortages and water pollution so they contribute more to water security risks. This study of the spatial variation of water security risks in Zhangjiakou can provide an important scientific reference for zone-based management and decision-making for reducing the water security risks in the farming-pastoral ecotone.
