With rapid urbanization process, the pace of urban sprawl has been quickened and most metropolises have ex-perienced expansions in leaps and bounds in suburbanization, which has greatly changed the urban and rural spa...With rapid urbanization process, the pace of urban sprawl has been quickened and most metropolises have ex-perienced expansions in leaps and bounds in suburbanization, which has greatly changed the urban and rural spatial struc-ture of the metropolis fringe area. In this paper, Shuangliu County is taken as a case, since it is a typical fringe area of Chengdu Metropolis. Based on Landsat TM images of Chengdu City and Shuangliu County obtained in 1985, 2000 and 2004, characteristics of urban and rural spatial structure in Shuangliu County were analyzed, such as core-periphery spa-tial structure and some obvious integration trends. Then the influencing factors for the formation of urban and rural spatial structure were identified, including some natural, social, economic and political factors. According to the discussion of this paper, Shuangliu County is undergoing a key transition and reform period. Its formation of urban and rural spatial structure was affected not only by such common factors as the location, natural background, industrial transition, migra-tion, etc., but also by some unique factors such as city planning and policy guidance, which played an important role in accelerating its uneven spatial structure. The understanding of the role of the influencing factors would be useful for car-rying out spatial management and development planning of metropolis fringe area.展开更多
In 2012 and 2013, the Swiss population voted on two separate yet related issues concerning spatial planning. In 2012 a restriction on second homes was introduced into the Constitution, in 2013 referendum the planning ...In 2012 and 2013, the Swiss population voted on two separate yet related issues concerning spatial planning. In 2012 a restriction on second homes was introduced into the Constitution, in 2013 referendum the planning law was revised. Both issues wanted to restrict disproportionate building activities, and were accepted after a heated debate. This outcome mirrors a change in popular attitude towards constructions in the countryside and so-called "cold beds" (second homes used for a short time only), but also towards the disfiguration of the (rural) landscape in general. At the same time it revealed two social rifts: between urban populations (that are increasingly migrating towards rural landscapes) and rural regions that want to obtain a similar level of living as the urban majority, and between lowland and mountain regions. The results of the referenda show that the population is very much concerned about the future of our landscape and environment. The paper discusses the two referenda and their implications for Switzerland in general and for regions that are considered marginal. Its focus lies on the political aspects of the two issues, which not only concern marginality but also are a challenge for national cohesion and direct democracy.展开更多
Built environments are undergoing a state of crisis, due to fragmentation and obsolescence: consolidated urban areas, suburbs and fringe areas require to be restored so as to recover a sense of vivid places and to av...Built environments are undergoing a state of crisis, due to fragmentation and obsolescence: consolidated urban areas, suburbs and fringe areas require to be restored so as to recover a sense of vivid places and to avoid segregation. Fabric of routes and voids can be considered as a medium in order to structure a landscape, to manage and govern a region, to nurture its unique subculture. A structure of bonds is to be designed to promote a rapid and safe movement of resources, of people, of ideas, even from and to most remote sites. Infrastructure can foster a vast economic development, and also, a profound social and cultural development.展开更多
Based on the geothermal and gravitation methods, this paper investigated the rheological and thermal structure of the lithosphere under the northern margin of South China Sea. The result shows that the temperature of ...Based on the geothermal and gravitation methods, this paper investigated the rheological and thermal structure of the lithosphere under the northern margin of South China Sea. The result shows that the temperature of the upper crust is 150–300°C lower than that of the lower crust, and the viscous coefficient of the upper crust is 2–3 orders of magnitude larger than that of the lower crust. It reveals that the upper crust is characterized by brittle deformation while the lower crust by ductile deformation. A channel of lower-viscosity should be formed between the upper and lower crust when the lithosphere is scattered and spreads out toward ocean from northwest to southeast along the northern margin of South China Sea. And, a brittle deformation takes place in the upper part of the lithosphere while a ductile deformation takes place in the lower part of the lithosphere due to different viscous coefficients and temperature. The layered deformation leads the faulted blocks to rotate along the faulting and the marginal grabens to appear in the northern margin of South China Sea in Cenozoic tectonic expansion.展开更多
By measuring the sand-dust flux,vertical deposition,and the wind velocity throughout 19 sandstorms in the Minqin region,we quantitatively analyzed the horizontal distribution and vertical variation in sandstorm charac...By measuring the sand-dust flux,vertical deposition,and the wind velocity throughout 19 sandstorms in the Minqin region,we quantitatively analyzed the horizontal distribution and vertical variation in sandstorm characteristics under different land cover conditions.The effect of different land cover on mitigating sandstorms was also investigated.The results indicated that,in the surface layer ranging from 0-50 m,the intensity of sand-dust horizontal flux and concentration of sand-dust decreased with the increase of the height in the desert and the edge of oasis,whereas the two physical quantities increased slightly with the increase of the height in the oasis.The two physical quantities obey power function well under all three cover conditions.Moreover,in the desert and at the edge of oasis,the sand-dust vertical deposition decreased with the increase of the height.But a partial unimodal distribution at the oasis site and the maximum deposition occurred at the height of 9 m,which corresponds to the middle height of farmland protection forest.The annual flux that passed through a section of 1 m in width and 50 m in height was 9169 kg in the desert,5318 kg at the edge of oasis,and 2345 kg in the oasis.And the annual fluxes at the edge of oasis and in the oasis are 42% and 74% less,respectively,than that in the desert.This implies that the wind break forest significantly reduced the intensity of sandstorms.展开更多
基金Under the auspices of National Natural Science Foundation of China (No 40571056)
文摘With rapid urbanization process, the pace of urban sprawl has been quickened and most metropolises have ex-perienced expansions in leaps and bounds in suburbanization, which has greatly changed the urban and rural spatial struc-ture of the metropolis fringe area. In this paper, Shuangliu County is taken as a case, since it is a typical fringe area of Chengdu Metropolis. Based on Landsat TM images of Chengdu City and Shuangliu County obtained in 1985, 2000 and 2004, characteristics of urban and rural spatial structure in Shuangliu County were analyzed, such as core-periphery spa-tial structure and some obvious integration trends. Then the influencing factors for the formation of urban and rural spatial structure were identified, including some natural, social, economic and political factors. According to the discussion of this paper, Shuangliu County is undergoing a key transition and reform period. Its formation of urban and rural spatial structure was affected not only by such common factors as the location, natural background, industrial transition, migra-tion, etc., but also by some unique factors such as city planning and policy guidance, which played an important role in accelerating its uneven spatial structure. The understanding of the role of the influencing factors would be useful for car-rying out spatial management and development planning of metropolis fringe area.
文摘In 2012 and 2013, the Swiss population voted on two separate yet related issues concerning spatial planning. In 2012 a restriction on second homes was introduced into the Constitution, in 2013 referendum the planning law was revised. Both issues wanted to restrict disproportionate building activities, and were accepted after a heated debate. This outcome mirrors a change in popular attitude towards constructions in the countryside and so-called "cold beds" (second homes used for a short time only), but also towards the disfiguration of the (rural) landscape in general. At the same time it revealed two social rifts: between urban populations (that are increasingly migrating towards rural landscapes) and rural regions that want to obtain a similar level of living as the urban majority, and between lowland and mountain regions. The results of the referenda show that the population is very much concerned about the future of our landscape and environment. The paper discusses the two referenda and their implications for Switzerland in general and for regions that are considered marginal. Its focus lies on the political aspects of the two issues, which not only concern marginality but also are a challenge for national cohesion and direct democracy.
文摘Built environments are undergoing a state of crisis, due to fragmentation and obsolescence: consolidated urban areas, suburbs and fringe areas require to be restored so as to recover a sense of vivid places and to avoid segregation. Fabric of routes and voids can be considered as a medium in order to structure a landscape, to manage and govern a region, to nurture its unique subculture. A structure of bonds is to be designed to promote a rapid and safe movement of resources, of people, of ideas, even from and to most remote sites. Infrastructure can foster a vast economic development, and also, a profound social and cultural development.
基金the National Natural Science Foundation of China (Grant Nos.49732005, 49733011) and the Chinese Academy of Sciences (Grant No. KZ951-A1-401). We wish to thank Prof. Xu Houze and Lu Yang for their contribution in gravitational model. The authors also than
文摘Based on the geothermal and gravitation methods, this paper investigated the rheological and thermal structure of the lithosphere under the northern margin of South China Sea. The result shows that the temperature of the upper crust is 150–300°C lower than that of the lower crust, and the viscous coefficient of the upper crust is 2–3 orders of magnitude larger than that of the lower crust. It reveals that the upper crust is characterized by brittle deformation while the lower crust by ductile deformation. A channel of lower-viscosity should be formed between the upper and lower crust when the lithosphere is scattered and spreads out toward ocean from northwest to southeast along the northern margin of South China Sea. And, a brittle deformation takes place in the upper part of the lithosphere while a ductile deformation takes place in the lower part of the lithosphere due to different viscous coefficients and temperature. The layered deformation leads the faulted blocks to rotate along the faulting and the marginal grabens to appear in the northern margin of South China Sea in Cenozoic tectonic expansion.
基金supported by National Natural Science Foundation of China (Grant Nos. 30872069, 30960321)National Commonweal Special Research of Forestry of China (Grant No. 200804031)
文摘By measuring the sand-dust flux,vertical deposition,and the wind velocity throughout 19 sandstorms in the Minqin region,we quantitatively analyzed the horizontal distribution and vertical variation in sandstorm characteristics under different land cover conditions.The effect of different land cover on mitigating sandstorms was also investigated.The results indicated that,in the surface layer ranging from 0-50 m,the intensity of sand-dust horizontal flux and concentration of sand-dust decreased with the increase of the height in the desert and the edge of oasis,whereas the two physical quantities increased slightly with the increase of the height in the oasis.The two physical quantities obey power function well under all three cover conditions.Moreover,in the desert and at the edge of oasis,the sand-dust vertical deposition decreased with the increase of the height.But a partial unimodal distribution at the oasis site and the maximum deposition occurred at the height of 9 m,which corresponds to the middle height of farmland protection forest.The annual flux that passed through a section of 1 m in width and 50 m in height was 9169 kg in the desert,5318 kg at the edge of oasis,and 2345 kg in the oasis.And the annual fluxes at the edge of oasis and in the oasis are 42% and 74% less,respectively,than that in the desert.This implies that the wind break forest significantly reduced the intensity of sandstorms.