The synergistic relationship between urban functions and street networks has al-ways been a focus in the field of urban research and practice.From the perspective of street networks,by adopting space syntax,this study...The synergistic relationship between urban functions and street networks has al-ways been a focus in the field of urban research and practice.From the perspective of street networks,by adopting space syntax,this study analyzed the deep structural characteristics and potential evolution rules of commercial blocks attached to street networks in different periods,as well as the corresponding economic,political,and cultural characteristics of an-cient Beijing city over the past 800 years.By combining these with changes in the street network,we further explained the function mechanism of layout and level adjustment in commercial blocks,and the influence of the street network on commercial blocks in the process of historical change.The main conclusions included the following:(1)The urban centripetal-centrifugal siphon effect:the layout form,topological structure,and traffic mode changes in the street network had corresponding guidance for the layout and hierarchical system of commercial blocks,while the centripetal development of the street network could guide the agglomeration effect of commercial blocks,although centrifugal development caused commercial blocks to display outward evacuation.(2)Stage transformation from mu-tation node to smooth development:the layout of commercial blocks came to depend on the ability to cross the commuting flow center,which originally relied on the accessibility of transportation nodes as local centers.Changes in traffic modes mainly affected the adjust-ment of the first-level commercial blocks,which easily led to overall layout mutation.Traffic levels have an obvious positive hierarchical relation with the second-and third-level com-mercial blocks.(3)The adaptation of traditional commercial blocks to the needs of a modern city:affected by the different emerging times and unevenness of the original commercial foundation,commercial blocks have formed various developmental models that meet the needs of modernization,and reach a balance between cultural continuity and functional ad-aptation.展开更多
In addition to socio-economic factors, major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Irani...In addition to socio-economic factors, major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Iranian cities of Dezful （a river） and Khorramabad （moun- tains and valleys）, but no clear effects on the cities of Yazd and Nain. Also, where the street orientation is peaked, the Gibbs/Shannon entropy （a measure of dispersion or spread） is low, but increases as the distribution becomes more uniform because of landform constraints. The streets in the old inner parts of all the cities are, on average, shorter and denser （more streets per unit area） than the streets of the newer outer parts. The entropies of the outer parts are also greater than those of the inner parts, implying that the street-length distribution gradually becomes more dispersed or spread as the city expands. All these cities have been fast growing in the past decades, with the newer outer parts expanding rapidly. As shown here, the rapidly formed outer parts （with greater dispersion in street patterns） have significantly different textures from those of the older inner parts, indicating different functionality and growth processes. These quantitative methods for street-network analysis can be used worldwide, particularly for analysing the effects of landforms on city shape and texture.展开更多
The huge amount of electrical power of many countries is consumed in lighting the streets. However, vehicles pass with very low rate in specific periods of time and parts of the streets are not occupied by vehicles ov...The huge amount of electrical power of many countries is consumed in lighting the streets. However, vehicles pass with very low rate in specific periods of time and parts of the streets are not occupied by vehicles over time. In this paper, we propose a system that automatically switches off the light for the parts of the streets having no vehicles and turns on the light for these parts once there are some vehicles that are going to come. Logically, this system may save a large amount of the electrical power. In addition, it may increase the lifetime of the lamps and reduce the pollutions. This system automatically controls and monitors the light of the streets. It can light only the parts that have vehicles and help on the maintenance of the lighting equipments. Vehicular Ad-Hoc Networks (VANET) make it possible to propose such system. VANET enables the possibility to know the presence of vehicles, their locations, their directions and their speeds in real time. These quantities are what are needed to develop this system. An advantage of using VANET is that there is no need to use specific network and equipments to design the system, but VANET infrastructure will be used. This decreases the cost and speed up the deployment of such system. This paper focuses on the proposal of different possible architectures of this system. Results show that the saved energy may reach up to 65% and an increase of the lifetime of the lamps of 53%.展开更多
The duality in China's traffic planning has given rise to the basic unit of urban form and function called the superblock,which is defined and bound by an arterial street network.The street network of China's ...The duality in China's traffic planning has given rise to the basic unit of urban form and function called the superblock,which is defined and bound by an arterial street network.The street network of China's superblock un derpins the coexiste nee and in teraction of global and local movement,the public and daily space,and affects place diversity and local characteristics.However,its configuration remains to be articulated because of the lack of a systematic representation method,and the associations between configuration and performance,cognition and design cannot be determi ned.This study proposes an improved representation method for the street network of China's superblocks based on Marshall's route structure analysis to explore the configurational characteristics and sustainability of the network.To fit local conditions,this study improves Marshall's route structure analysis from four perspectives,namely,the judgement of relative hierarchy,the node construction principle,and the deletion and addition of the original indicators.The improved method is then applied to calculate and compare the depth,connectivity,and complexity of the street networks of 10 sample superblocks in Nanjing,which are classified into six types by construction backgrounds,each having two seenarios differing by the level of publicity.Results indicate that the types formed in accordance with the"The Capital Plan"of the Republic of China,which presents a combination of fine orthogonal grids and radiations,and by the renewal of the traditional street-andlane network,which has the"characteristic structure" defined by Marshall,perform best in terms of configurational sustainability.The an alysis also reveals that the addition of semipublic streets formed mainly from the bottom up narrows the sustainability gap among the samples.This study provides a tool for elaborate urban study and design and provides in sights into the cognitive and practical aspects of China's urban planning and design.展开更多
基金National Natural Science Foundation of China,No.51778005Sino-German Center(National Natural Science Foundation of China and German Science Foundation),No.GZ1201
文摘The synergistic relationship between urban functions and street networks has al-ways been a focus in the field of urban research and practice.From the perspective of street networks,by adopting space syntax,this study analyzed the deep structural characteristics and potential evolution rules of commercial blocks attached to street networks in different periods,as well as the corresponding economic,political,and cultural characteristics of an-cient Beijing city over the past 800 years.By combining these with changes in the street network,we further explained the function mechanism of layout and level adjustment in commercial blocks,and the influence of the street network on commercial blocks in the process of historical change.The main conclusions included the following:(1)The urban centripetal-centrifugal siphon effect:the layout form,topological structure,and traffic mode changes in the street network had corresponding guidance for the layout and hierarchical system of commercial blocks,while the centripetal development of the street network could guide the agglomeration effect of commercial blocks,although centrifugal development caused commercial blocks to display outward evacuation.(2)Stage transformation from mu-tation node to smooth development:the layout of commercial blocks came to depend on the ability to cross the commuting flow center,which originally relied on the accessibility of transportation nodes as local centers.Changes in traffic modes mainly affected the adjust-ment of the first-level commercial blocks,which easily led to overall layout mutation.Traffic levels have an obvious positive hierarchical relation with the second-and third-level com-mercial blocks.(3)The adaptation of traditional commercial blocks to the needs of a modern city:affected by the different emerging times and unevenness of the original commercial foundation,commercial blocks have formed various developmental models that meet the needs of modernization,and reach a balance between cultural continuity and functional ad-aptation.
文摘In addition to socio-economic factors, major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Iranian cities of Dezful （a river） and Khorramabad （moun- tains and valleys）, but no clear effects on the cities of Yazd and Nain. Also, where the street orientation is peaked, the Gibbs/Shannon entropy （a measure of dispersion or spread） is low, but increases as the distribution becomes more uniform because of landform constraints. The streets in the old inner parts of all the cities are, on average, shorter and denser （more streets per unit area） than the streets of the newer outer parts. The entropies of the outer parts are also greater than those of the inner parts, implying that the street-length distribution gradually becomes more dispersed or spread as the city expands. All these cities have been fast growing in the past decades, with the newer outer parts expanding rapidly. As shown here, the rapidly formed outer parts （with greater dispersion in street patterns） have significantly different textures from those of the older inner parts, indicating different functionality and growth processes. These quantitative methods for street-network analysis can be used worldwide, particularly for analysing the effects of landforms on city shape and texture.
文摘The huge amount of electrical power of many countries is consumed in lighting the streets. However, vehicles pass with very low rate in specific periods of time and parts of the streets are not occupied by vehicles over time. In this paper, we propose a system that automatically switches off the light for the parts of the streets having no vehicles and turns on the light for these parts once there are some vehicles that are going to come. Logically, this system may save a large amount of the electrical power. In addition, it may increase the lifetime of the lamps and reduce the pollutions. This system automatically controls and monitors the light of the streets. It can light only the parts that have vehicles and help on the maintenance of the lighting equipments. Vehicular Ad-Hoc Networks (VANET) make it possible to propose such system. VANET enables the possibility to know the presence of vehicles, their locations, their directions and their speeds in real time. These quantities are what are needed to develop this system. An advantage of using VANET is that there is no need to use specific network and equipments to design the system, but VANET infrastructure will be used. This decreases the cost and speed up the deployment of such system. This paper focuses on the proposal of different possible architectures of this system. Results show that the saved energy may reach up to 65% and an increase of the lifetime of the lamps of 53%.
基金sponsored by the National Natural Science Foundation of China(NSFC#51578123)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYLX16_0234).
文摘The duality in China's traffic planning has given rise to the basic unit of urban form and function called the superblock,which is defined and bound by an arterial street network.The street network of China's superblock un derpins the coexiste nee and in teraction of global and local movement,the public and daily space,and affects place diversity and local characteristics.However,its configuration remains to be articulated because of the lack of a systematic representation method,and the associations between configuration and performance,cognition and design cannot be determi ned.This study proposes an improved representation method for the street network of China's superblocks based on Marshall's route structure analysis to explore the configurational characteristics and sustainability of the network.To fit local conditions,this study improves Marshall's route structure analysis from four perspectives,namely,the judgement of relative hierarchy,the node construction principle,and the deletion and addition of the original indicators.The improved method is then applied to calculate and compare the depth,connectivity,and complexity of the street networks of 10 sample superblocks in Nanjing,which are classified into six types by construction backgrounds,each having two seenarios differing by the level of publicity.Results indicate that the types formed in accordance with the"The Capital Plan"of the Republic of China,which presents a combination of fine orthogonal grids and radiations,and by the renewal of the traditional street-andlane network,which has the"characteristic structure" defined by Marshall,perform best in terms of configurational sustainability.The an alysis also reveals that the addition of semipublic streets formed mainly from the bottom up narrows the sustainability gap among the samples.This study provides a tool for elaborate urban study and design and provides in sights into the cognitive and practical aspects of China's urban planning and design.
