A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,China.The 3D images of the lig...A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,China.The 3D images of the lightning progression have been obtained successfully for the first time in China.The 3D-channel evolutions of typical negative CG,positive CG and IC lightning flashes have been discussed together with the data of fast electric field change.It was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation sources.The preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2×104 m/s.The stepped leader of negative CG lightning flashes was trigged by negative initial breakdown.Thereafter,it propagated downward at a speed of 1.3×105 m/s.The initial process of the positive CG lightning flashes was also a propagation process of negative streamer.These streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning,and as a consequence,initiated downward positive streamers.A new type of lightning discharge that was triggered by a narrow bipolar pulse(NBP) is discussed in this study.The NBP was originated at altitude of about 10.5 km in the upper positive charge region.As a distinct difference from normal IC flash,its channels extended horizontally all around and produced a lot of radiation sources.The source power of the NBP could approach 16.7 kW,which is much greater than that of normal lightning discharge ranging between 100 mW and 500 W.The 3D propagation of this new type of lightning discharge was observed and obtained for the first time in China.The possible initiation mechanism of this new type of light-ning is discussed here.展开更多
The future development of new-type urbanization has drawn great attention from both the government and public alike. In this context, the present study had three related research aims. Firstly, it sought to predict th...The future development of new-type urbanization has drawn great attention from both the government and public alike. In this context, the present study had three related research aims. Firstly, it sought to predict the urbanization and population dynamics in China at both national and provincial levels for the period of 2015 to 2030. Secondly, on this basis, it sought to examine the spatial variation of urbanization given the predicted national urbaniza- tion rate of 70.12%. Thirdly, it sought to estimate and evaluate the national and provincial demands of investment in the development of new-type urbanization. The main conclusions from this study were as follows： （1） The population size and urbanization rate will reach 1.445 billion and 70.12%, respectively, from 2015 to 2030. （2） The demographic dividend will vanish when the population pressure reaches its maximum. During this period, there will be 70.16 million urban population born. The suburban population that becomes urbanized will be 316.7 million, and thus the net increase in urban population will reach 386 million. （3） Although the urbanization rate of every Chinese province will increase during 2015-2030, it will do so un- equally, while differences in urbanization quality among provinces will also be substantial. In some provinces, moreover, the urbanization quality is not compatible with their eco-social development. （4）A total of 4,105,380 billion yuan is required to fund new-type urbanization and the investment demand for each province varies greatly; for example, Guangdong prov- ince requires the most funding, amounting to approximately 148 times that required by Tibet, the province in least need of funding. In the final part of this study, policy suggestions con- cerning the investment of the new-type urbanization are put forward and discussed.展开更多
Although the factors affecting rural-to-urban migration have been discussed and analyzed in detail, few studies have examined the spatiotemporal dynamic characteristics of rural migrants’ employment and working-citie...Although the factors affecting rural-to-urban migration have been discussed and analyzed in detail, few studies have examined the spatiotemporal dynamic characteristics of rural migrants’ employment and working-cities in the post-immigrate era, which is essential for the citizenization and social integration of new-type urbanization in China. This study uses survey data from rural migration laborers across the eastern, central, and western China to construct a comprehensive labor migration stability index, and compares the determinants of the migration stability of rural labor among cities and industries using Geodetector. The results are as follows: 1) Compared with the midwestern cities, eastern cities have attracted younger and more skilled rural labor, and industries with higher technical content have higher migration stability among rural laborers. 2) Rural laborers more often adapt to changes by changing employment instead of changing working-cities. 3) The individual experiences of rural laborers and urban characteristics have significant impacts on the stability of migration, and family and societal guanxi(Chinese interpersonal relationships) enhance migration stability. 4) A unified labor market and convenient transportation have somewhat slowed industrial transfers and labor backflow. This study enhances our understanding of the roles of industrial transfer and new-type urbanization in shaping the labor geography landscape and provides policy implications for the promotion of people-oriented urbanization.展开更多
This paper uses the fifth and sixth census data and 2018 demographic statistics to analyze the spatiotemporal evolution of the urbanization of county in China and the factors that influence the evolution.The paper rev...This paper uses the fifth and sixth census data and 2018 demographic statistics to analyze the spatiotemporal evolution of the urbanization of county in China and the factors that influence the evolution.The paper reveals that the urbanization level of counties is a weak area in China’s overall urbanization.During the period from 2000 to 2010,the spatial patterns of the urbanization level of counties remained stable.Counties with high-level urbanization were concentrated in the coastal areas of the eastern region,while counties that experienced rapid urbanization were mainly located in the central and western regions.Regression analyses indicate that harsh natural endowments that constrain economic development are the most important factors that hinder the urbanization of county;these factors include marginalized locations far away from center cities,high altitudes,and a population with a low education level.This paper also compares two theoretical modes of new-type urbanization,nearby urbanization and remote urbanization,and argues that the new-type urbanization of county is the main form of nearby urbanization and provides an example of urbanization for developing countries worldwide.展开更多
Perovskite solar cells(PSCs) have drawn wide attention due to the rapidly rising efficiency which presently attains over 23%. However, problems of instability continue to plague the high-efficiency devices impairing t...Perovskite solar cells(PSCs) have drawn wide attention due to the rapidly rising efficiency which presently attains over 23%. However, problems of instability continue to plague the high-efficiency devices impairing their practical applications. Here, by firstly introducing smaller-size NH4+ into(FAPbI3)0.85(MAPbBr3)0.15(FA/MA) to form a novel 2D-3D mixed structure, we designed and prepared new-type hybrid perovskite materials of [(NH4)2.4(FA)n-1PbnI3n+1.4]0.85(MAPbBr3)0.15(n=3, 5, 7, 9 and 11)(A/FA/MA) and used them as absorber in solar cells. Especially, unlike the reported 2D/MD perovskite perovskites based on larger-size ammonium salts;A/FA/MA perovskites are the first to display red-shift light absorption and decreased band gaps in comparison to normal perovskites. Consequently, when n=9, the A/FA/MA device shows outstanding performance with a solar to electric power conversion efficiency(PCE) of 18.25% and negligible hysteresis. When the encapsulated A/FA/MA perovskite device was soaked in full sunlight for 1,000 h, the PCE remains almost unchanged. Moreover, the unsealed A/FA/MA PSCs maintain 90% of their initial PCE when aged at high humidity conditions over the same 1000-h time period. Our findings provide a guide for the future development of such novel perovskites and it is helpful to select more suitable ammonium salt to obtain highly efficient and stable 2D-3D PSCs.展开更多
Distributed energy systems(DES),as an integrated energy system with coupled distributed energy resources,have great potential in reducing carbon dioxide emissions and improving energy efficiencies.Considering the back...Distributed energy systems(DES),as an integrated energy system with coupled distributed energy resources,have great potential in reducing carbon dioxide emissions and improving energy efficiencies.Considering the background of urbanization and the energy revolution in China,the study investigates the renewable-based DESs supply modes and their application in China.A new method is proposed to classify DESs supply modes into three categories considering the renewable resource in domination,and their application domains are discussed.A comprehensive model is given for economic and environmental evaluation.Typical case studies show that the renewable-based DES systems can supply the energy in a cost-effective and environment-friendly way.Among them,the biomass waste dominated supply mode can not only achieve"zero"carbon emissions but also"zero"energy consumption,even though not yet economically attractive under the present policy and market conditions.Thus,recommendations are given to promote the further deployment of renewable-based DESs,regarding their supply modes,policy requirements,and issues to be addressed.展开更多
From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target a...From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.展开更多
基金supported by National Natural Science Foundation of China (Grant No.40775004)Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KZCX2-YW-206-2)the R & D Special Fund for Public Welfare Industry (meteorology) (Grant No.GYHY2007622)
文摘A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,China.The 3D images of the lightning progression have been obtained successfully for the first time in China.The 3D-channel evolutions of typical negative CG,positive CG and IC lightning flashes have been discussed together with the data of fast electric field change.It was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation sources.The preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2×104 m/s.The stepped leader of negative CG lightning flashes was trigged by negative initial breakdown.Thereafter,it propagated downward at a speed of 1.3×105 m/s.The initial process of the positive CG lightning flashes was also a propagation process of negative streamer.These streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning,and as a consequence,initiated downward positive streamers.A new type of lightning discharge that was triggered by a narrow bipolar pulse(NBP) is discussed in this study.The NBP was originated at altitude of about 10.5 km in the upper positive charge region.As a distinct difference from normal IC flash,its channels extended horizontally all around and produced a lot of radiation sources.The source power of the NBP could approach 16.7 kW,which is much greater than that of normal lightning discharge ranging between 100 mW and 500 W.The 3D propagation of this new type of lightning discharge was observed and obtained for the first time in China.The possible initiation mechanism of this new type of light-ning is discussed here.
基金National Natural Science Foundation of China, No.41501137, No.41530634, No.41271186
文摘The future development of new-type urbanization has drawn great attention from both the government and public alike. In this context, the present study had three related research aims. Firstly, it sought to predict the urbanization and population dynamics in China at both national and provincial levels for the period of 2015 to 2030. Secondly, on this basis, it sought to examine the spatial variation of urbanization given the predicted national urbaniza- tion rate of 70.12%. Thirdly, it sought to estimate and evaluate the national and provincial demands of investment in the development of new-type urbanization. The main conclusions from this study were as follows： （1） The population size and urbanization rate will reach 1.445 billion and 70.12%, respectively, from 2015 to 2030. （2） The demographic dividend will vanish when the population pressure reaches its maximum. During this period, there will be 70.16 million urban population born. The suburban population that becomes urbanized will be 316.7 million, and thus the net increase in urban population will reach 386 million. （3） Although the urbanization rate of every Chinese province will increase during 2015-2030, it will do so un- equally, while differences in urbanization quality among provinces will also be substantial. In some provinces, moreover, the urbanization quality is not compatible with their eco-social development. （4）A total of 4,105,380 billion yuan is required to fund new-type urbanization and the investment demand for each province varies greatly; for example, Guangdong prov- ince requires the most funding, amounting to approximately 148 times that required by Tibet, the province in least need of funding. In the final part of this study, policy suggestions con- cerning the investment of the new-type urbanization are put forward and discussed.
基金the auspices of the National Natural Science Foundation of China(No.41471469)the Key Project of National Natural Science Found of China(No.41930651)Sichuan Provincial Research Center for Philosophy and Social Sciences-Sichuan Rural Development Research Center(No.CR1908)。
文摘Although the factors affecting rural-to-urban migration have been discussed and analyzed in detail, few studies have examined the spatiotemporal dynamic characteristics of rural migrants’ employment and working-cities in the post-immigrate era, which is essential for the citizenization and social integration of new-type urbanization in China. This study uses survey data from rural migration laborers across the eastern, central, and western China to construct a comprehensive labor migration stability index, and compares the determinants of the migration stability of rural labor among cities and industries using Geodetector. The results are as follows: 1) Compared with the midwestern cities, eastern cities have attracted younger and more skilled rural labor, and industries with higher technical content have higher migration stability among rural laborers. 2) Rural laborers more often adapt to changes by changing employment instead of changing working-cities. 3) The individual experiences of rural laborers and urban characteristics have significant impacts on the stability of migration, and family and societal guanxi(Chinese interpersonal relationships) enhance migration stability. 4) A unified labor market and convenient transportation have somewhat slowed industrial transfers and labor backflow. This study enhances our understanding of the roles of industrial transfer and new-type urbanization in shaping the labor geography landscape and provides policy implications for the promotion of people-oriented urbanization.
基金The Second Tibetan Plateau Scientific Expedition and Research Program,No.2019QZKK0406National Natural Science Foundation of ChinaNo.42171204。
文摘This paper uses the fifth and sixth census data and 2018 demographic statistics to analyze the spatiotemporal evolution of the urbanization of county in China and the factors that influence the evolution.The paper reveals that the urbanization level of counties is a weak area in China’s overall urbanization.During the period from 2000 to 2010,the spatial patterns of the urbanization level of counties remained stable.Counties with high-level urbanization were concentrated in the coastal areas of the eastern region,while counties that experienced rapid urbanization were mainly located in the central and western regions.Regression analyses indicate that harsh natural endowments that constrain economic development are the most important factors that hinder the urbanization of county;these factors include marginalized locations far away from center cities,high altitudes,and a population with a low education level.This paper also compares two theoretical modes of new-type urbanization,nearby urbanization and remote urbanization,and argues that the new-type urbanization of county is the main form of nearby urbanization and provides an example of urbanization for developing countries worldwide.
基金financially supported by the National Key Research and Development Program of China (2016YFA0202401)the National Natural Science Foundation of China (51572080)
文摘Perovskite solar cells(PSCs) have drawn wide attention due to the rapidly rising efficiency which presently attains over 23%. However, problems of instability continue to plague the high-efficiency devices impairing their practical applications. Here, by firstly introducing smaller-size NH4+ into(FAPbI3)0.85(MAPbBr3)0.15(FA/MA) to form a novel 2D-3D mixed structure, we designed and prepared new-type hybrid perovskite materials of [(NH4)2.4(FA)n-1PbnI3n+1.4]0.85(MAPbBr3)0.15(n=3, 5, 7, 9 and 11)(A/FA/MA) and used them as absorber in solar cells. Especially, unlike the reported 2D/MD perovskite perovskites based on larger-size ammonium salts;A/FA/MA perovskites are the first to display red-shift light absorption and decreased band gaps in comparison to normal perovskites. Consequently, when n=9, the A/FA/MA device shows outstanding performance with a solar to electric power conversion efficiency(PCE) of 18.25% and negligible hysteresis. When the encapsulated A/FA/MA perovskite device was soaked in full sunlight for 1,000 h, the PCE remains almost unchanged. Moreover, the unsealed A/FA/MA PSCs maintain 90% of their initial PCE when aged at high humidity conditions over the same 1000-h time period. Our findings provide a guide for the future development of such novel perovskites and it is helpful to select more suitable ammonium salt to obtain highly efficient and stable 2D-3D PSCs.
基金supported by National Key Research and Development Program of China(No.2016YFB0900100)Sate Grid of China(Research on the development potential evaluation of distributed generation and its management and control and operation optimization technology under scaleup development stage.No.1400-201927279A-0-0-00)
文摘Distributed energy systems(DES),as an integrated energy system with coupled distributed energy resources,have great potential in reducing carbon dioxide emissions and improving energy efficiencies.Considering the background of urbanization and the energy revolution in China,the study investigates the renewable-based DESs supply modes and their application in China.A new method is proposed to classify DESs supply modes into three categories considering the renewable resource in domination,and their application domains are discussed.A comprehensive model is given for economic and environmental evaluation.Typical case studies show that the renewable-based DES systems can supply the energy in a cost-effective and environment-friendly way.Among them,the biomass waste dominated supply mode can not only achieve"zero"carbon emissions but also"zero"energy consumption,even though not yet economically attractive under the present policy and market conditions.Thus,recommendations are given to promote the further deployment of renewable-based DESs,regarding their supply modes,policy requirements,and issues to be addressed.
基金the Key Program of the National Natural Science Foundation of China (Grant No. 90411014)the National Natural Science Foundation of China (Grant Nos. 40576032 and 40506016).
文摘From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.
