A numerical study based on a two-dimensional two-phase SPH(Smoothed Particle Hydrodynamics)model to analyze the action of water waves on open-type sea access roads is presented.The study is a continuation of the analy...A numerical study based on a two-dimensional two-phase SPH(Smoothed Particle Hydrodynamics)model to analyze the action of water waves on open-type sea access roads is presented.The study is a continuation of the analyses presented by Chen et al.(2022),in which the sea access roads are semi-immersed.In this new configuration,the sea access roads are placed above the still water level,therefore the presence of the air phase becomes a relevant issue in the determination of the wave forces acting on the structures.Indeed,the comparison of wave forces on the open-type sea access roads obtained from the single and two-phase SPH models with the experimental results shows that the latter are in much better agreement.So in the numerical simulations,a two-phaseδ-SPH model is adopted to investigate the dynamical problems.Based on the numerical results,the maximum horizontal and uplifting wave forces acting on the sea access roads are analyzed by considering different wave conditions and geometries of the structures.In particular,the presence of the girder is analyzed and the differences in the wave forces due to the air cushion effects which are created below the structure are highlighted.展开更多
Based on space syntax theory, the spatial accessibility of the road network in Wuhan Metropolitan Area has been quantitatively analyzed by building a series of accessibility variables. Topologic connectivity in the ac...Based on space syntax theory, the spatial accessibility of the road network in Wuhan Metropolitan Area has been quantitatively analyzed by building a series of accessibility variables. Topologic connectivity in the accessible rings appears to be broken;traffic axis network is in spatial structure of hub-and-spoke and fishbone-like. Meanwhile, the differences in classified road network have led to inefficiency of its network servo and its ever-worsening capability to respond to traffic jams. Besides, two band-like integrated cores of which one is east to west along the Yangtze River and the other is north to south along Beijing to Guangzhou Railway, have become the first level traffic axis in the whole network, which is responsible for the connectivity of the entire metropolitan area network. This consequently has strengthened the dominant position of Wuhan which is located on the bands’ crossing. In short, the spatial accessibility of that classified space morphology, the urban system, the transport infrastructure as well as the social and economic development of Wuhan Metropolitan Area are highly interrelated to each other, especially to the high level highway network featured by freeways, the development level of which is well in line with that of road network accessibility.展开更多
Before the emergence of modern modes of transport, the traditional road infra structure was the major historical means of carrying out nationwide socioeconomic exchange However, the history of transport infrastructure...Before the emergence of modern modes of transport, the traditional road infra structure was the major historical means of carrying out nationwide socioeconomic exchange However, the history of transport infrastructure has received little attention from researchers. Given this background, the work reported here examined the longterm development of transport networks in China. The national road network was selected for study and the 3500 years from 1600 BC to 1900 AD was chosen as the study period. Indicators were designed for the maturity level of road networks and an accessibility model was developed for the paths of the shortest distance. The evolution of the road network in China since the Shang Dynasty （1600 BC） was described and its major features were summarized to reveal longterm regu larities. The maturity level of the road network and its accessibility was assessed and regions with good and poor networks were identified. The relationship between China＇s natural, social and economic systems and the road network were discussed. Our analysis shows that the road network in China has a number of longterm regularities. The continuously expanding road network follows a path of inland expansion especially towards the border areas. How ever, its coverage and accessibility are characterized by a coreperipheral configuration, which has close relationships with, not only the natural conditions, but also national defense and warfare. The centralization of national power, national land governance, postal transport, the transport of specialized cargos, and international trade are also related to the develop ment of the road network. This research draws attention to the evolving regularities of trans port networks.展开更多
Agriculture is related to the strategy and security of a country. Every country is very discreet about access of foreign capitals to the agricultural field. Countries along the " Belt and Road" also have imp...Agriculture is related to the strategy and security of a country. Every country is very discreet about access of foreign capitals to the agricultural field. Countries along the " Belt and Road" also have imposed restrictions on the access of foreign capitals to the agricultural field.There are restrictions on establishing agriculture-related enterprises,affiliated organizations,and branch offices. Also,there are regulations concerning the scope,proportion,performance requirement,and approval of access of foreign capitals to the agricultural field.展开更多
Road accessibility is considered to be one of the major factors influencing (or correlated to) rural households’ access to- and participation in markets. However, there are few studies that investigate this important...Road accessibility is considered to be one of the major factors influencing (or correlated to) rural households’ access to- and participation in markets. However, there are few studies that investigate this important topic. This paper, therefore, explores the issue from both theoretical and practical perspectives with household and village level data from Northern Ethiopia. It is generally assumed that road accessibility significantly contributes to both access to- and participation in markets by rural households. The results in this study, however, suggest that neither participation in major markets nor the amount of purchased agricultural inputs use are significantly different for households with respect to the degree of road accessibility in the study area. Nevertheless, the situation seems somewhat better in locations with good access to roads. On the other hand, the results in this study confirm that road accessibility significantly contributes to reducing farm gate prices of manufactured goods and increasing farm gate prices of agricultural goods.展开更多
Aiming at the problem of lack of data model to analyze the level of transportation integration, the paper taking Changsha-Zhuzhou-Xiangtan City Group of China as the research object, based on the Gravity measurement m...Aiming at the problem of lack of data model to analyze the level of transportation integration, the paper taking Changsha-Zhuzhou-Xiangtan City Group of China as the research object, based on the Gravity measurement model, transportation comprehensive distance model, weighted road density model, analysis of Changsha-Zhuzhou-Xiangtan City Group accessibility and transportation integration level. A new method to measure the level of traffic integration is proposed and verified by the road network data and socio-economic data of Changsha-Zhuzhou-Xiangtan City Group. The results show that: Changsha-Zhuzhou-Xiangtan City Group traffic accessibility was “point to surface” shape distribution, taking the core region of Changsha as the optimal, Xiangtan, Zhuzhou, Changsha County next, in remote Yanling County, Chaling county has the lowest accessibility;the correlation between traffic network connection degree and economic connection degree reached 0.871, indicating that the transportation integration level of urban agglomerations has a high degree of fit with the level of economic integration. The research results on the one hand for the Chang-Zhuzhou-Xiangtan urban agglomeration traffic present situation to make an annotation;on the other hand, that provide a reference for further optimization of Changsha-Zhuzhou-Xiangtan urban agglomeration traffic planning.展开更多
To determinate the combined effect of bus bay stops near access points on the expressway capacity,a new theoretical approach is developed on the basis of gap acceptance theory and queuing theory. According to the loca...To determinate the combined effect of bus bay stops near access points on the expressway capacity,a new theoretical approach is developed on the basis of gap acceptance theory and queuing theory. According to the location between the bus stop and the access upstream or downstream,the capacity models on the expressway are developed for four cases. The results show that there are no significant differences in the capacity among four cases when the bus arrival rate is less than 60 veh / h and the car volume at the entrance and exit is less than 200 pcu / h. As the bus arrival rate and the car volume at the entrance and exit increase,the bus stops at downstream of an entrance and upstream of an exit have remarkable effect on the capacity. The increasing of berth number of the bus stop has a positive effect on the capacities of four cases.展开更多
基金supported by the New Cornerstone Science Foundation through the XPLORER PRIZE and the National Natural Science Foundation of China(Grant No.52088102).
文摘A numerical study based on a two-dimensional two-phase SPH(Smoothed Particle Hydrodynamics)model to analyze the action of water waves on open-type sea access roads is presented.The study is a continuation of the analyses presented by Chen et al.(2022),in which the sea access roads are semi-immersed.In this new configuration,the sea access roads are placed above the still water level,therefore the presence of the air phase becomes a relevant issue in the determination of the wave forces acting on the structures.Indeed,the comparison of wave forces on the open-type sea access roads obtained from the single and two-phase SPH models with the experimental results shows that the latter are in much better agreement.So in the numerical simulations,a two-phaseδ-SPH model is adopted to investigate the dynamical problems.Based on the numerical results,the maximum horizontal and uplifting wave forces acting on the sea access roads are analyzed by considering different wave conditions and geometries of the structures.In particular,the presence of the girder is analyzed and the differences in the wave forces due to the air cushion effects which are created below the structure are highlighted.
文摘Based on space syntax theory, the spatial accessibility of the road network in Wuhan Metropolitan Area has been quantitatively analyzed by building a series of accessibility variables. Topologic connectivity in the accessible rings appears to be broken;traffic axis network is in spatial structure of hub-and-spoke and fishbone-like. Meanwhile, the differences in classified road network have led to inefficiency of its network servo and its ever-worsening capability to respond to traffic jams. Besides, two band-like integrated cores of which one is east to west along the Yangtze River and the other is north to south along Beijing to Guangzhou Railway, have become the first level traffic axis in the whole network, which is responsible for the connectivity of the entire metropolitan area network. This consequently has strengthened the dominant position of Wuhan which is located on the bands’ crossing. In short, the spatial accessibility of that classified space morphology, the urban system, the transport infrastructure as well as the social and economic development of Wuhan Metropolitan Area are highly interrelated to each other, especially to the high level highway network featured by freeways, the development level of which is well in line with that of road network accessibility.
基金Key Research Program of the Chinese Academy of Sciences, No.KZZD-EW-06-02 Exploratory Forefront Project for the Strategic Science Plan in IGSNRR, CAS, No.2012QY004 National Natural Science Foundation of China, No.41171108
文摘Before the emergence of modern modes of transport, the traditional road infra structure was the major historical means of carrying out nationwide socioeconomic exchange However, the history of transport infrastructure has received little attention from researchers. Given this background, the work reported here examined the longterm development of transport networks in China. The national road network was selected for study and the 3500 years from 1600 BC to 1900 AD was chosen as the study period. Indicators were designed for the maturity level of road networks and an accessibility model was developed for the paths of the shortest distance. The evolution of the road network in China since the Shang Dynasty （1600 BC） was described and its major features were summarized to reveal longterm regu larities. The maturity level of the road network and its accessibility was assessed and regions with good and poor networks were identified. The relationship between China＇s natural, social and economic systems and the road network were discussed. Our analysis shows that the road network in China has a number of longterm regularities. The continuously expanding road network follows a path of inland expansion especially towards the border areas. How ever, its coverage and accessibility are characterized by a coreperipheral configuration, which has close relationships with, not only the natural conditions, but also national defense and warfare. The centralization of national power, national land governance, postal transport, the transport of specialized cargos, and international trade are also related to the develop ment of the road network. This research draws attention to the evolving regularities of trans port networks.
基金Supported by Young Scholar Project of Humanities and Social Science Foundation of Ministry of Education(17YJC820044)Social Science Planning PhD Project of Chongqing(2017BS39)
文摘Agriculture is related to the strategy and security of a country. Every country is very discreet about access of foreign capitals to the agricultural field. Countries along the " Belt and Road" also have imposed restrictions on the access of foreign capitals to the agricultural field.There are restrictions on establishing agriculture-related enterprises,affiliated organizations,and branch offices. Also,there are regulations concerning the scope,proportion,performance requirement,and approval of access of foreign capitals to the agricultural field.
文摘Road accessibility is considered to be one of the major factors influencing (or correlated to) rural households’ access to- and participation in markets. However, there are few studies that investigate this important topic. This paper, therefore, explores the issue from both theoretical and practical perspectives with household and village level data from Northern Ethiopia. It is generally assumed that road accessibility significantly contributes to both access to- and participation in markets by rural households. The results in this study, however, suggest that neither participation in major markets nor the amount of purchased agricultural inputs use are significantly different for households with respect to the degree of road accessibility in the study area. Nevertheless, the situation seems somewhat better in locations with good access to roads. On the other hand, the results in this study confirm that road accessibility significantly contributes to reducing farm gate prices of manufactured goods and increasing farm gate prices of agricultural goods.
文摘Aiming at the problem of lack of data model to analyze the level of transportation integration, the paper taking Changsha-Zhuzhou-Xiangtan City Group of China as the research object, based on the Gravity measurement model, transportation comprehensive distance model, weighted road density model, analysis of Changsha-Zhuzhou-Xiangtan City Group accessibility and transportation integration level. A new method to measure the level of traffic integration is proposed and verified by the road network data and socio-economic data of Changsha-Zhuzhou-Xiangtan City Group. The results show that: Changsha-Zhuzhou-Xiangtan City Group traffic accessibility was “point to surface” shape distribution, taking the core region of Changsha as the optimal, Xiangtan, Zhuzhou, Changsha County next, in remote Yanling County, Chaling county has the lowest accessibility;the correlation between traffic network connection degree and economic connection degree reached 0.871, indicating that the transportation integration level of urban agglomerations has a high degree of fit with the level of economic integration. The research results on the one hand for the Chang-Zhuzhou-Xiangtan urban agglomeration traffic present situation to make an annotation;on the other hand, that provide a reference for further optimization of Changsha-Zhuzhou-Xiangtan urban agglomeration traffic planning.
基金National Basic Research Program of China(No.2012CB723303)
文摘To determinate the combined effect of bus bay stops near access points on the expressway capacity,a new theoretical approach is developed on the basis of gap acceptance theory and queuing theory. According to the location between the bus stop and the access upstream or downstream,the capacity models on the expressway are developed for four cases. The results show that there are no significant differences in the capacity among four cases when the bus arrival rate is less than 60 veh / h and the car volume at the entrance and exit is less than 200 pcu / h. As the bus arrival rate and the car volume at the entrance and exit increase,the bus stops at downstream of an entrance and upstream of an exit have remarkable effect on the capacity. The increasing of berth number of the bus stop has a positive effect on the capacities of four cases.
