To detect the impacts of urban surface expansion on surface air temperature at 2-m（SAT） in Shanghai, China, nested numerical integrations based on satellite-derived urban data between the 1980 s and 2010 s were perf...To detect the impacts of urban surface expansion on surface air temperature at 2-m（SAT） in Shanghai, China, nested numerical integrations based on satellite-derived urban data between the 1980 s and 2010 s were performed using the Weather Research and Forecasting（WRF） model. Urban surface expansion induced an annual-averaged warming of 0.31 °C from 1980 to 2016 across the whole of Shanghai, showing the greatest intensity between 2010 and 2016. The values were 0.36, 0.78, and 0.75 °C over grids that were classified as urban in both time periods（U2 U）, landuse grids that changed from non-urban to urban（N2 U）, and urban areas（including U2 U and N2 U）, respectively, and revealed weak warming over the inner-ring areas because the urban surfaces had been there since the 1980 s, whereas warming areas were coincident with the outward expansion of the urban surface. Meanwhile, marked seasonal variations could be detected, which were greater in spring and summer but less in autumn and winter. The approximately homogenously distributed SAT maximum（weaker） and heterogeneously SAT minimum（stronger） contributed to the decreased diurnal temperature range. Regional warming induced by urban surface expansion was approximately 0.12 °C per decade, which accounted for 19% of the overall warming across the whole of Shanghai. The values were 0.11 °C per decade and 0.39 °C per decade over U2 U and N2 U, which accounted for approximately 17% and 42% of the overall warming, respectively, and resulted in approximately 41% of the overall warming over urban areas.展开更多
The economic regionalization practice led by China local governments has gradually evolved into chaos. Local governments compete to declare for higher-leveled and large-scaled economic regions to obtain more economic ...The economic regionalization practice led by China local governments has gradually evolved into chaos. Local governments compete to declare for higher-leveled and large-scaled economic regions to obtain more economic resources and policy support in the way of policy game. The author argues that the regionalization chaos is attributed to the reason that the present theoretical support for economic regionalization overemphasizes the economic growth brought about by the economic regionalization but ignores the effect of transaction cost, which leads to constraint loss on the economic regionalization theory analysis framework. Then, the introduction of economic regionalization analysis framework based on the conflicts between scale expansion and transaction costs would establish equilibrium conditions to set up a moderate scale development for economic regions. The author hopes that the acceptance of this framework into the economic regionalization decision-making system would give guidance for making more appropriate regionalization decisions.展开更多
The expansion of the estimated stability region plays an important role in the stability analysis of nonlinear systems.However,current literatures have not provided a complete mathematical description for this problem...The expansion of the estimated stability region plays an important role in the stability analysis of nonlinear systems.However,current literatures have not provided a complete mathematical description for this problem.This paper reveals that essentially the enlargement or the compression of the estimated stability region results directly from the diffeomorphism map,which is induced by the flow contained in the stability region.By proving that any integration algorithm with an order higher than one can approximately trace the flow of the system,a generalized methodology is proposed to construct various algorithms to realize the enlargement or the compression of the estimated stability region.With this methodology,two new algorithms based on symbolic calculation are suggested to reduce the computational burden.Furthermore,this methodology is applied to construct a scalable numerical algorithm to calculate the critical clearing time(CCT) of the power system for given faults.Tests on the IEEE 10-machine 39-bus system show that the computational results coincide well with the step-by-step simulation with high accuracy.展开更多
基金supported by the National Natural Science Foundation of China[grant number 41775087]the National Natural Science Foundation of China[grant number 41675149]+2 种基金National Key R&D Program of China[grant number 2016YFA0600403]the Chinese Academy of Sciences Strategic Priority Program[grant number XDA05090206]the Jiangsu Collaborative Innovation Center for Climatic Change
文摘To detect the impacts of urban surface expansion on surface air temperature at 2-m（SAT） in Shanghai, China, nested numerical integrations based on satellite-derived urban data between the 1980 s and 2010 s were performed using the Weather Research and Forecasting（WRF） model. Urban surface expansion induced an annual-averaged warming of 0.31 °C from 1980 to 2016 across the whole of Shanghai, showing the greatest intensity between 2010 and 2016. The values were 0.36, 0.78, and 0.75 °C over grids that were classified as urban in both time periods（U2 U）, landuse grids that changed from non-urban to urban（N2 U）, and urban areas（including U2 U and N2 U）, respectively, and revealed weak warming over the inner-ring areas because the urban surfaces had been there since the 1980 s, whereas warming areas were coincident with the outward expansion of the urban surface. Meanwhile, marked seasonal variations could be detected, which were greater in spring and summer but less in autumn and winter. The approximately homogenously distributed SAT maximum（weaker） and heterogeneously SAT minimum（stronger） contributed to the decreased diurnal temperature range. Regional warming induced by urban surface expansion was approximately 0.12 °C per decade, which accounted for 19% of the overall warming across the whole of Shanghai. The values were 0.11 °C per decade and 0.39 °C per decade over U2 U and N2 U, which accounted for approximately 17% and 42% of the overall warming, respectively, and resulted in approximately 41% of the overall warming over urban areas.
文摘The economic regionalization practice led by China local governments has gradually evolved into chaos. Local governments compete to declare for higher-leveled and large-scaled economic regions to obtain more economic resources and policy support in the way of policy game. The author argues that the regionalization chaos is attributed to the reason that the present theoretical support for economic regionalization overemphasizes the economic growth brought about by the economic regionalization but ignores the effect of transaction cost, which leads to constraint loss on the economic regionalization theory analysis framework. Then, the introduction of economic regionalization analysis framework based on the conflicts between scale expansion and transaction costs would establish equilibrium conditions to set up a moderate scale development for economic regions. The author hopes that the acceptance of this framework into the economic regionalization decision-making system would give guidance for making more appropriate regionalization decisions.
基金supported by the National Natural Science Foundation (Grant Nos 50525721, 50595411)
文摘The expansion of the estimated stability region plays an important role in the stability analysis of nonlinear systems.However,current literatures have not provided a complete mathematical description for this problem.This paper reveals that essentially the enlargement or the compression of the estimated stability region results directly from the diffeomorphism map,which is induced by the flow contained in the stability region.By proving that any integration algorithm with an order higher than one can approximately trace the flow of the system,a generalized methodology is proposed to construct various algorithms to realize the enlargement or the compression of the estimated stability region.With this methodology,two new algorithms based on symbolic calculation are suggested to reduce the computational burden.Furthermore,this methodology is applied to construct a scalable numerical algorithm to calculate the critical clearing time(CCT) of the power system for given faults.Tests on the IEEE 10-machine 39-bus system show that the computational results coincide well with the step-by-step simulation with high accuracy.
