Rapid morphological and socioeconomic changes have accelerated the urbanization process and urban land use transformation in China.Megacities comprise clusters of urban cities and exhibit both newly formed and well-de...Rapid morphological and socioeconomic changes have accelerated the urbanization process and urban land use transformation in China.Megacities comprise clusters of urban cities and exhibit both newly formed and well-developed urban land use development beyond administrative boundaries.It is necessary to distinguish the changing effects of spatial-varying driving factors on newly formed urban land uses from well-developed built-up areas in megacities.This study proposed a multi-spatial urbanization framework to quantify region-level socioeconomics,cluster-level ecological morphologies,and grid-level urban functional morphologies.A three-level Bayesian hierarchical model was developed to investigate the impacts of multi-spatial driving factors on urban land use transformation in megacities.The study period focused on the urbanization process between 2000 and 2018 in Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Results revealed that compared with well-developed urban built-up land,changing impacts of three-level driving factors in urban land use transformation could be captured based on the proposed Bayesian hierarchical model.The region-level total population was associated with increasing possibilities in forming new residential land than the well-developed ones in 35 districts/counties/cities in GBA.Cluster-level ecological attributes with higher proportion,lower edge density of urban built areas,and lower-degree ecological complexity showed increasing probability on newly formed industrial and public land.Grid-level urban functional factors including public transportation density and shopping/dining distribution exhibited significantly decreasing probability(coefficients:−2.12 to−0.51)on contributing newly formed land uses compared with the well-developed areas,whereas business/industry distribution represented higher(coefficients:0.99 and 0.15)and lower probabilities(coefficient:−0.22)of forming industrial/public land and residential land separately.This research shows a new attempt to distinguish multi-spatial morphological and socioeconomic effects in urban land use transformation in megacities.展开更多
In this article, per capita urban carbon emissions were decomposed into manufacturing,transportation, and construction sectors using logarithmic mean Divisia index(LMDI)method. This new decomposition method can provid...In this article, per capita urban carbon emissions were decomposed into manufacturing,transportation, and construction sectors using logarithmic mean Divisia index(LMDI)method. This new decomposition method can provide information about specific drivers of carbon emissions, including urban growth and resident living standards, rather than general demographic and economic factors identified by traditional methods. Using four Chinese megacities(Beijing, Tianjin, Shanghai, and Chongqing) as case studies, we analyzed the factors that influenced per capita carbon emissions from 2010 to 2015. The results showed that per capita carbon emissions increased in Tianjin and Chongqing whereas decreased in Beijing and Shanghai, and that manufacturing was a key driving force. In these four megacities,energy conservation strategies were successfully implemented despite poor energy structure optimization during 2010–2015. Development of manufacturing and improvement of resident living standards in the cities led to an increase in carbon emissions. The unique dual-core urban form of Tianjin might mitigate the increased carbon emissions caused by the transportation sector. Reductions in carbon emissions could be achieved by further optimizing energy structures, limiting the number of private cars, and controlling per capita construction.展开更多
During the prevention of coronavirus disease 2019(COVID-19),epidemiological data is essential for controlling the source of infection,cutting off the route of transmission,and protecting vulnerable populations.Followi...During the prevention of coronavirus disease 2019(COVID-19),epidemiological data is essential for controlling the source of infection,cutting off the route of transmission,and protecting vulnerable populations.Following Law of the People's Republic of China on Prevention and Treatment of Infectious Diseases and other related regulations,medical institutions have been authorized to collect the detailed information of patients,while it is still a formidable task in megacities because of the significant patient mobility and the existing information sharing barrier.As a smart city which strengthens precise epidemic prevention and control,Shanghai has established a multi-department platform named"one-net management"on dynamic information monitoring.By sharing epidemiological data with medical institutions under a safe environment,we believe that the ability to prevent and control epidemics among medical institutions will be effectively and comprehensively improved.展开更多
Objective Improvement in the quality of life is reflected in the narrowing of the gap between healthadjusted life expectancy(HALE)and life expectancy(LE).The effect of megacity expansion on narrowing the gap is rarely...Objective Improvement in the quality of life is reflected in the narrowing of the gap between healthadjusted life expectancy(HALE)and life expectancy(LE).The effect of megacity expansion on narrowing the gap is rarely reported.This study aimed to disclose this potential relationship.Methods Annual life tables were constructed from identified death records and population counts from multiple administrative sources in Guangzhou,China,from 2010 to 2020.Joinpoint regression was used to evaluate the temporal trend.Generalized principal component analysis and multilevel models were applied to examine the county-level association between the gap and social determinants.Results Although LE and HALE in megacities are increasing steadily,their gap is widening.Socioeconomic and health services are guaranteed to narrow this gap.Increasing personal wealth,a growing number of newborns and healthy immigrants,high urbanization,and healthy aging have helped in narrowing this gap.Conclusion In megacities,parallel LE and HALE growth should be highly considered to narrow their gap.Multiple social determinants need to be integrated as a whole to formulate public health plans.展开更多
In the process of new urbanization,the population of megacities is increasing rapidly,the scale of cities is expanding,and the supply of service facilities has been unable to meet the demand.As an important carrier of...In the process of new urbanization,the population of megacities is increasing rapidly,the scale of cities is expanding,and the supply of service facilities has been unable to meet the demand.As an important carrier of urban governance and urban management,the police station should properly deal with the existing problems in the urban police stations,and improve the quality of life of residents by optimizing urban service facilities,which is of great significance for the implementation of people-oriented new urbanization.Taking Changping District of Beijing as an example,this study pointed out that there were many problems in police stations in Changping District.For example,the area of land is not up to the standard,the service capacity is not up to the demand,and the facilities are not up to the demand.Then,three planning strategies:adjusting the planning standards of facilities,optimizing the spatial layout of facilities,and strengthening the later guarantee of facilities were put forward,so as to improve people’s satisfaction with life,promote the high-quality development of new urbanization,and provide reference for the supplement of service facilities in megacities.展开更多
Space monitoring of aerosol optical depth (AOD) trends over megacities can serve as a potential space indicator of global anthropogenic air-pollution changes. Three space aerosol sensors, MODIS-Terra, MODIS-Aqua and M...Space monitoring of aerosol optical depth (AOD) trends over megacities can serve as a potential space indicator of global anthropogenic air-pollution changes. Three space aerosol sensors, MODIS-Terra, MODIS-Aqua and MISR, were used in order to study recent decadal trends of AOD over megacities around the world. Space monitoring of AOD trends has the advantage of global coverage and applies the same approach to detecting AOD trends over different sites. In spite of instrumental and time differences among the three sensors investigated, their global pictures of AOD trends over the 189 largest cities in the world are quite similar. The increasing AOD trends over the largest cities in the Indian subcontinent, the Middle East, and North China can be clearly seen. By contrast, megacities in Europe, the north-east of US, and South-East Asia show mainly declining AOD trends. In the cases where all three sensors show similar signs of AOD trends, the results can be considered as reliable. This is supported by the observed trends in surface solar radiation, obtained by using network pyranometer measurements in North and South China, India, and Europe. In the cases where the three sensors show differing signs of AOD trends (e.g. South America), additional research is required in order to verify the obtained AOD trends.展开更多
As urbanization expands＇ into the suburbs of Chinese cities, the conversion of farmers into citizens with urban social protection is becoming an important issue facing Chinese megacities. Taking Beijing as an example...As urbanization expands＇ into the suburbs of Chinese cities, the conversion of farmers into citizens with urban social protection is becoming an important issue facing Chinese megacities. Taking Beijing as an example, this paper has calculated the one-off urbanization cost of farmers in China and arrived at the results of 500, 000 yuan per person for urbanization of centralized target regions in the suburb and 200, 000 yuan per person for urbanization of scattered target regions in the exurb. This paper considers that a diversified cost sharing mechanism should be put into place for the step-by-step urbanization of farmers. In addition, policy recommendations are proposed regarding the functional transformation of collective economic organizations, eradication of the urban-rural divide, enhancement of land system innovation and policy improvements for urbanization of rural residents.展开更多
Ⅰ. MAIN TRAFFIC PROBLEMS IN THE MEGACITIES IN CHINA (1) Road capacity is far from enough The road space per capita in China’s megacities has long been very limited and it is only recently did it began to increase fr...Ⅰ. MAIN TRAFFIC PROBLEMS IN THE MEGACITIES IN CHINA (1) Road capacity is far from enough The road space per capita in China’s megacities has long been very limited and it is only recently did it began to increase from 2.8 to 6.6 square meters.But, fast as it is, this change still cannot meet the demand of the growing urban traffic volume with an average annual rate of 20 percent. At present,among the 34 cities populated over one million people each in China, 27 are being suffered by展开更多
COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) wit...COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) with limited relaxation in non-hotspot areas. This strict lockdown has severely curtailed human activity across India. Here, aerosol concentrations of particular matters(PM) i.e., PM,PM, carbon monoxide(CO), nitrogen dioxide(NO), sulphur dioxide(SO), ammonia(NH) and ozone(O), and associated temperature fluctuation in four megacities(Delhi, Mumbai, Kolkata, and Chennai)from different regions of India were investigated. In this pandemic period, air temperature of Delhi,Kolkata, Mumbai and Chennai has decreased about 3 ℃, 2.5 ℃, 2 ℃ and 2 ℃ respectively. Compared to previous years and pre-lockdown period, air pollutants level and aerosol concentration(-41.91%,-37.13%,-54.94% and-46.79% respectively for Delhi, Mumbai, Kolkata and Chennai) in these four megacities has improved drastically during this lockdown period. Emission of PMhas experienced the highest decrease in these megacities, which directly shows the positive impact of restricted vehicular movement. Restricted emissions produce encouraging results in terms of urban air quality and temperature, which may encourage policymakers to consider it in terms of environmental sustainability.展开更多
The Belt and Road(B&R)region,a vital area with historical,economic,cultural and political significance,has undergone rapid urbanization in the past several decades,especially in the form of urban expansion.In this...The Belt and Road(B&R)region,a vital area with historical,economic,cultural and political significance,has undergone rapid urbanization in the past several decades,especially in the form of urban expansion.In this study,20 megacities in the B&R region were selected to explore different spatiotemporal patterns of urban expansion.Object-oriented support vector machines(SVM),annual growth rate(AGR)models,and landscape metrics were employed to delineate the urban areas and characterize spatiotemporal characteristics and landscape patterns of these megacities during 1975–2015.All urban maps presented high overall accuracies(80.70%–95.90%)and overall Kappa coefficients(0.76–0.95).The study revealed that megacities in the B&R region have undergone different types of urban sprawl,mainly adopting a‘concentric circle’pattern in inland areas and a‘sector’pattern in coastal areas.Besides,six expansion modes were summarized according to the AGRs of individual megacities.Differences existed in megacities of the developing and developed countries and among five sub-regions.Moreover,‘dispersion,gathering,and re-dispersion’and‘coalescence’were two major landscape patterns of megacities in developing and developed countries.Results of this study can provide a scientific reference for urban planning and aid in sustainable development of local areas.展开更多
The authors regret that in 1.2.Instruments section of the article,when describing the principle of TiH300,the original content of“Briefly,ambient HONO was first absorbed by deionized water in a two-channel stripping ...The authors regret that in 1.2.Instruments section of the article,when describing the principle of TiH300,the original content of“Briefly,ambient HONO was first absorbed by deionized water in a two-channel stripping coil.The absorbed liquid nitrite was mixed with sulfanilamide,N-(1-naphthyl)-ethylenediamine dihydrochloride,and hydrogen chloride solution to form the azo dye derivative.”展开更多
Carbonyl-containing volatile organic compounds （cVOCs） are important precursors of atmospheric photochemical reactions in the formation of ozone, smog and other air pollutants. China＇s megacities are economically d...Carbonyl-containing volatile organic compounds （cVOCs） are important precursors of atmospheric photochemical reactions in the formation of ozone, smog and other air pollutants. China＇s megacities are economically developed and densely populated metropolitan areas, usually with a population over ten million; they drive the rapid growth of surrounding urban clusters. So far, 21 cVOCs have been detected in the atmosphere of these megacities. The average annual total concentration of cVOCs is 55.6 μg/m^3, an alarmingly high level. Vehicle emissions, industrial discharges, excessive use of organic solvents and other factors have led to a situation where hazardous formaldehyde, acetaldehyde and acetone account for 62.4 percent of the total atmospheric concentration of cVOC in Chinese cities. In a quantitative evaluation using daily exposure levels, cancer risk and hazardquotient, we found that the excessive levels of atmospheric cVOCs in Beijing, Shanghai and Guangzhou pose serious health risks to their inhabitants. Air pollution persists, despite the brief improvements in air quality brought about by the air quality campaign undertaken during major intemational events like the 2008 Olympic Games, the 2010 Asian Games, and the 2010 World Expo. The health risks caused by atmospheric cVOCs in Chinese cities require close attention.展开更多
Urbanization is one of the most important social and economic phenomena in the world today.This paper reviews the formation of megacities and summarizes the main problems,challenges and opportunities faced by the sust...Urbanization is one of the most important social and economic phenomena in the world today.This paper reviews the formation of megacities and summarizes the main problems,challenges and opportunities faced by the sustainable development of such large megacities.Issues discussed include the problems of land subsidence in megacities,environmental issues,traffic problems and energy supply aspects.The sustainable development of megacities in other parts of the world provided the references and experiences for the countermeasures of megacity planning and development in China.The vision of Digital Earth and Digital Cities can play a major role in the efficient management and sustainable growth of such megacities all around the world.展开更多
Megacities serve as global centers for economic,cultural,and high-tech industries.The structural features and population agglomerations are typical traits of urbanization,yet little is known about the morphological fe...Megacities serve as global centers for economic,cultural,and high-tech industries.The structural features and population agglomerations are typical traits of urbanization,yet little is known about the morphological features and expansion patterns of megacities worldwide.Here we examined the spatiotemporal variations of urban land in megalopolises from 2000 to 2020 using the Urban Expansion Intensity Differentiation Index.The fractal features and expansion patterns of megacities were analyzed using the Area-Radius Multi-dimensional Scaling Model.Urban land use efficiency was then evaluated based on the linear relationship between urban land area and population.We found that Southeast Asia and China were the hotspots of urban expansion in megacities from 2000 to 2020,with urban land areas expanding by 3148.32 km^(2)and 5996.26 km^(2),respectively.The morphological features and expansion patterns of megacities exhibited a growing trend towards intensification and compactness,with the average radial dimension increasing from 1.54 to 1.56.The annual decrease in fractal dimensions indicated the integration of inner urban areas.North America and Europe megacities showed a low urban land use efficiency,with a ratio of urban land area to population ranging from 0.89 to 4.11 in 2020.Conversely,South Asia and Africa megacities exhibited a high urban land use efficiency,with the ratios between 0.23 and 0.87.Our results provide information for promoting efficient urban land utilization and sustainable cities.It is proposed to control the scale of urban expansion and to promote balanced development between inner and outer urban areas for achieving resilient and sustainable urban development.展开更多
Several factors may contribute to on-going challenges for spatial planning and policy in megacities such as Rome, including rapid population shifts, poorly organized areas, and lack of data through which monitoring ur...Several factors may contribute to on-going challenges for spatial planning and policy in megacities such as Rome, including rapid population shifts, poorly organized areas, and lack of data through which monitoring urban growth and land use change. This research was conducted to examine past and current effects of the urbanization process, occurred over the large Roman urban system, on the basis of multi-source and multi-temporal optical remote sensing (RS) data, collected between 1990 and 2013. These changes were then validated via Geographic Information System (GIS) techniques, in a particular procedure applied to urban land/agricultural transformations. The proposed approach, based on geo-statistical methods, was used to calculate the index of innovative space (AP Index), useful for the monitoring of the urban sprawl phenomenon. Strong evidence of urban expansion over the north-eastern quarter of the city, accompanied by environmental degradation and loss of biodiversity, is provided. Urban infill developments are expected to emerge in the south-eastern areas too, and these might increase urban pressure as well. In conclusion, RS and GIS technologies together with ancillary data can be used to assist decision makers in preparing future plans to find out appropriate solutions to urbanization encroachment.展开更多
Adaptation is the pursuit of active, deliberate measures to enhance humankind’s capacity to manage water supply and attenuate demand in the face of climate uncertainty. This article contends that worsening constraint...Adaptation is the pursuit of active, deliberate measures to enhance humankind’s capacity to manage water supply and attenuate demand in the face of climate uncertainty. This article contends that worsening constraints upon freshwater due to climate variability demand concerted, imaginative, science-based solutions. These solutions must join creative management to co-production of climate knowledge. Through a series of case studies, we analyze the need for adaptation approaches to prevail over climate variability, and the role of these factors to facilitate their implementation. We also examine how translation of climate knowledge is helping spur adaptation at various spatial levels. These experiences point to the challenges in adaptation, and the adversity various regions will be faced if we do not.展开更多
The transformation of Chengdu Tianfu New Area,a state-level new district,from the first site of constructing the“Park City”to the representative of the“Park City”,contains a unique path of“Chinese Style Governanc...The transformation of Chengdu Tianfu New Area,a state-level new district,from the first site of constructing the“Park City”to the representative of the“Park City”,contains a unique path of“Chinese Style Governance”.To expand the diverse paths of constructing megacities,the current research references the nudge theory of behavioral science,adopts the extended case method,and takes Chengdu Tianfu New Area as a typical case to summarize the“nudge”path of“Party City”construction.The study found that the government achieves the lock-in effect by the priming mechanism and uses the nudge strategy of improving environment and guiding public opinion,thereby helping the people make free choices.It realizes the framework effect by the salience mechanism and uses the strategies of highlighting key information and optimizing information delivery methods,which directly affects the behavior of the public.It achieves the commitment effect by the comparison mechanism,including the horizontal comparison and vertical comparison strategies,and gradually realizes the policy goals.It realizes the social norm effect by the imitation mechanism and uses the strategies of creating peer pressure and playing celebrity effect,which in turn influence people’s choices.With the help of the“nudging”mechanism,the construction of the park city has realized the interactive cycle of“government output-citizen feedback”and achieved the goal of“making great change through small actions”.As a new behavioral intervention tool,“nudging”provides an alternative explanation for the construction of the park city in Tianfu New Area and opens up new ideas for the construction of megacities.This study concludes that the construction of megacities can achieve the goal of“common return”through different ways and provides practical inspiration for future urban construction.展开更多
China has witnessed unprecedented urbanization over the past decades. The rapid expansion of urban population has been dominantly contributed by the floating population from rural areas, of which the spatiotemporal pa...China has witnessed unprecedented urbanization over the past decades. The rapid expansion of urban population has been dominantly contributed by the floating population from rural areas, of which the spatiotemporal patterns, driving forces, and multidimensional effects are scrutinized and evaluated in this study by using the latest national censuses conducted in 2000 and 2010. Analysis based on the county-level data comes to conclusions as follows. The spatial pattern of floating population has remained stable over the first decade of the new century. The top 1% cities with the largest floating population received 45.5% of all migrants in China. As the rapid development of mega-city regions, the coastal concentration areas of floating population tended to geographically united as a whole, whereas the spatial distribution of migrants within each region varied significantly. The migrant concentration area in the Yangtze River Delta was the largest and its expansion was also the most salient. However, the floating population has growingly moved into provincial capitals and other big cities in the inland regions and its gravity center has moved northward for around 110 km during the study period. The spatial pattern of floating population has been formed jointly by the state and market forces in transitional China and the impacts of state forces have been surpassed by those of market forces in the country as a whole. The attractiveness of coastal cities and counties to the floating population comes mainly from the nonagricultural employment opportunities and public services, reflecting that long-distance and long-term migrants have moved coastward not only to gain employment but also to enjoy city life. By contrast, in the central and western regions, places with a higher economic development level and at a higher administrative level are more attractive to floating populations, demonstrating that the state remains to play an important role in allocating economic resources and promoting regional development in inland China. As the main body of new urban residents, the floating population has contributed substantially to the elevation of the urbanization levels of migrant-sending and -receiving places, by 20.0% and 49.5% respectively. Compared with ex- tensively investigated interprovincial migrants, intra-provincial migrants have higher intention and ability to permanently live in cities and thus might become the main force of China＇s urbanization in the coming decades. The internal migration has also reshaped China＇s urban system in terms of its hierarchical organization and spatial structure.展开更多
Tianjin is the third largest megacity and the fastest growth area in China,and consequently faces the problems of surface ozone and haze episodes.This study measures and characterizes volatile organic compounds （VOCs...Tianjin is the third largest megacity and the fastest growth area in China,and consequently faces the problems of surface ozone and haze episodes.This study measures and characterizes volatile organic compounds （VOCs）,which are ozone precursors,to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin,China during the HaChi （Haze in China） summer campaign in 2009.A total of 107 species of ambient VOCs were detected,and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv,respectively.Of those,51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization.The identified sources of VOCs were significantly related to vehicular activities,which specifically contributed 60％ to urban and 42％ to suburban VOCs loadings in Tianjin.Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas,although the contribution of industry in the suburban area （36％） was much higher than that at the urban area （16％）.We conclude that controlling vehicle emissions should be a top priority for VOC reduction,and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life,especially in suburban areas.展开更多
基金supported by the General Research Fund[grant numbers 15602619,15603920,14605920,and 14611621]the Collaborative Research Fund[grant numbers C5062-21GF and C4023-20GF]from the Hong Kong Research Grants Council+1 种基金the Research Institute for Land and Space of the Hong Kong Polytechnic University[grant number 1-CD81]the Research Committee on Research Sustainability of Major Research Grants Council Funding Schemes of the Chinese University of Hong Kong.
文摘Rapid morphological and socioeconomic changes have accelerated the urbanization process and urban land use transformation in China.Megacities comprise clusters of urban cities and exhibit both newly formed and well-developed urban land use development beyond administrative boundaries.It is necessary to distinguish the changing effects of spatial-varying driving factors on newly formed urban land uses from well-developed built-up areas in megacities.This study proposed a multi-spatial urbanization framework to quantify region-level socioeconomics,cluster-level ecological morphologies,and grid-level urban functional morphologies.A three-level Bayesian hierarchical model was developed to investigate the impacts of multi-spatial driving factors on urban land use transformation in megacities.The study period focused on the urbanization process between 2000 and 2018 in Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Results revealed that compared with well-developed urban built-up land,changing impacts of three-level driving factors in urban land use transformation could be captured based on the proposed Bayesian hierarchical model.The region-level total population was associated with increasing possibilities in forming new residential land than the well-developed ones in 35 districts/counties/cities in GBA.Cluster-level ecological attributes with higher proportion,lower edge density of urban built areas,and lower-degree ecological complexity showed increasing probability on newly formed industrial and public land.Grid-level urban functional factors including public transportation density and shopping/dining distribution exhibited significantly decreasing probability(coefficients:−2.12 to−0.51)on contributing newly formed land uses compared with the well-developed areas,whereas business/industry distribution represented higher(coefficients:0.99 and 0.15)and lower probabilities(coefficient:−0.22)of forming industrial/public land and residential land separately.This research shows a new attempt to distinguish multi-spatial morphological and socioeconomic effects in urban land use transformation in megacities.
基金supported by the National Key Research & Development Program of China (No.2017YFF0207302)the National Natural Science Foundation of China (Nos.71573242 and 71273252)
文摘In this article, per capita urban carbon emissions were decomposed into manufacturing,transportation, and construction sectors using logarithmic mean Divisia index(LMDI)method. This new decomposition method can provide information about specific drivers of carbon emissions, including urban growth and resident living standards, rather than general demographic and economic factors identified by traditional methods. Using four Chinese megacities(Beijing, Tianjin, Shanghai, and Chongqing) as case studies, we analyzed the factors that influenced per capita carbon emissions from 2010 to 2015. The results showed that per capita carbon emissions increased in Tianjin and Chongqing whereas decreased in Beijing and Shanghai, and that manufacturing was a key driving force. In these four megacities,energy conservation strategies were successfully implemented despite poor energy structure optimization during 2010–2015. Development of manufacturing and improvement of resident living standards in the cities led to an increase in carbon emissions. The unique dual-core urban form of Tianjin might mitigate the increased carbon emissions caused by the transportation sector. Reductions in carbon emissions could be achieved by further optimizing energy structures, limiting the number of private cars, and controlling per capita construction.
文摘During the prevention of coronavirus disease 2019(COVID-19),epidemiological data is essential for controlling the source of infection,cutting off the route of transmission,and protecting vulnerable populations.Following Law of the People's Republic of China on Prevention and Treatment of Infectious Diseases and other related regulations,medical institutions have been authorized to collect the detailed information of patients,while it is still a formidable task in megacities because of the significant patient mobility and the existing information sharing barrier.As a smart city which strengthens precise epidemic prevention and control,Shanghai has established a multi-department platform named"one-net management"on dynamic information monitoring.By sharing epidemiological data with medical institutions under a safe environment,we believe that the ability to prevent and control epidemics among medical institutions will be effectively and comprehensively improved.
基金supported by the Guangdong Basic and Applied Basic Research Foundation[grant 2020A1515011294,2020A1515110230,and 2021A1515011765]the China Postdoctoral Science Foundation[grant 2021M693594]+1 种基金the Guangzhou Municipal Health Commission[grant No.2021-2023-12,No.20201A011054]Guangzhou Municipal Science and Technology Bureau[grant 2021BRP004]。
文摘Objective Improvement in the quality of life is reflected in the narrowing of the gap between healthadjusted life expectancy(HALE)and life expectancy(LE).The effect of megacity expansion on narrowing the gap is rarely reported.This study aimed to disclose this potential relationship.Methods Annual life tables were constructed from identified death records and population counts from multiple administrative sources in Guangzhou,China,from 2010 to 2020.Joinpoint regression was used to evaluate the temporal trend.Generalized principal component analysis and multilevel models were applied to examine the county-level association between the gap and social determinants.Results Although LE and HALE in megacities are increasing steadily,their gap is widening.Socioeconomic and health services are guaranteed to narrow this gap.Increasing personal wealth,a growing number of newborns and healthy immigrants,high urbanization,and healthy aging have helped in narrowing this gap.Conclusion In megacities,parallel LE and HALE growth should be highly considered to narrow their gap.Multiple social determinants need to be integrated as a whole to formulate public health plans.
基金Youth Fund Project of the National Natural Science Foundation of China(51608009)Youth Top Talent Training Project of Support Plan for the Construction of High-level Teachers of Beijing Municipal Colleges and Universities in 2019(CIT&TCD201904010).
文摘In the process of new urbanization,the population of megacities is increasing rapidly,the scale of cities is expanding,and the supply of service facilities has been unable to meet the demand.As an important carrier of urban governance and urban management,the police station should properly deal with the existing problems in the urban police stations,and improve the quality of life of residents by optimizing urban service facilities,which is of great significance for the implementation of people-oriented new urbanization.Taking Changping District of Beijing as an example,this study pointed out that there were many problems in police stations in Changping District.For example,the area of land is not up to the standard,the service capacity is not up to the demand,and the facilities are not up to the demand.Then,three planning strategies:adjusting the planning standards of facilities,optimizing the spatial layout of facilities,and strengthening the later guarantee of facilities were put forward,so as to improve people’s satisfaction with life,promote the high-quality development of new urbanization,and provide reference for the supplement of service facilities in megacities.
文摘Space monitoring of aerosol optical depth (AOD) trends over megacities can serve as a potential space indicator of global anthropogenic air-pollution changes. Three space aerosol sensors, MODIS-Terra, MODIS-Aqua and MISR, were used in order to study recent decadal trends of AOD over megacities around the world. Space monitoring of AOD trends has the advantage of global coverage and applies the same approach to detecting AOD trends over different sites. In spite of instrumental and time differences among the three sensors investigated, their global pictures of AOD trends over the 189 largest cities in the world are quite similar. The increasing AOD trends over the largest cities in the Indian subcontinent, the Middle East, and North China can be clearly seen. By contrast, megacities in Europe, the north-east of US, and South-East Asia show mainly declining AOD trends. In the cases where all three sensors show similar signs of AOD trends, the results can be considered as reliable. This is supported by the observed trends in surface solar radiation, obtained by using network pyranometer measurements in North and South China, India, and Europe. In the cases where the three sensors show differing signs of AOD trends (e.g. South America), additional research is required in order to verify the obtained AOD trends.
基金supported by CASS Innovation Project"Study on the Evaluation and Improvement of Urbanization Quality in the Chinese Mainland."
文摘As urbanization expands＇ into the suburbs of Chinese cities, the conversion of farmers into citizens with urban social protection is becoming an important issue facing Chinese megacities. Taking Beijing as an example, this paper has calculated the one-off urbanization cost of farmers in China and arrived at the results of 500, 000 yuan per person for urbanization of centralized target regions in the suburb and 200, 000 yuan per person for urbanization of scattered target regions in the exurb. This paper considers that a diversified cost sharing mechanism should be put into place for the step-by-step urbanization of farmers. In addition, policy recommendations are proposed regarding the functional transformation of collective economic organizations, eradication of the urban-rural divide, enhancement of land system innovation and policy improvements for urbanization of rural residents.
文摘Ⅰ. MAIN TRAFFIC PROBLEMS IN THE MEGACITIES IN CHINA (1) Road capacity is far from enough The road space per capita in China’s megacities has long been very limited and it is only recently did it began to increase from 2.8 to 6.6 square meters.But, fast as it is, this change still cannot meet the demand of the growing urban traffic volume with an average annual rate of 20 percent. At present,among the 34 cities populated over one million people each in China, 27 are being suffered by
文摘COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) with limited relaxation in non-hotspot areas. This strict lockdown has severely curtailed human activity across India. Here, aerosol concentrations of particular matters(PM) i.e., PM,PM, carbon monoxide(CO), nitrogen dioxide(NO), sulphur dioxide(SO), ammonia(NH) and ozone(O), and associated temperature fluctuation in four megacities(Delhi, Mumbai, Kolkata, and Chennai)from different regions of India were investigated. In this pandemic period, air temperature of Delhi,Kolkata, Mumbai and Chennai has decreased about 3 ℃, 2.5 ℃, 2 ℃ and 2 ℃ respectively. Compared to previous years and pre-lockdown period, air pollutants level and aerosol concentration(-41.91%,-37.13%,-54.94% and-46.79% respectively for Delhi, Mumbai, Kolkata and Chennai) in these four megacities has improved drastically during this lockdown period. Emission of PMhas experienced the highest decrease in these megacities, which directly shows the positive impact of restricted vehicular movement. Restricted emissions produce encouraging results in terms of urban air quality and temperature, which may encourage policymakers to consider it in terms of environmental sustainability.
基金supported by the Key R&D Program Projects in Hainan Province(grant number ZDYF2019008)Strategic Priority Research Program of the Chinese Academy of Sciences(grant number XDA19030104)+1 种基金National Key 84 Z.SUN ET AL.Research and Development Program(grant number 2016YFA0600302)the National Natural Science Foundation of China(grant number 41201357).
文摘The Belt and Road(B&R)region,a vital area with historical,economic,cultural and political significance,has undergone rapid urbanization in the past several decades,especially in the form of urban expansion.In this study,20 megacities in the B&R region were selected to explore different spatiotemporal patterns of urban expansion.Object-oriented support vector machines(SVM),annual growth rate(AGR)models,and landscape metrics were employed to delineate the urban areas and characterize spatiotemporal characteristics and landscape patterns of these megacities during 1975–2015.All urban maps presented high overall accuracies(80.70%–95.90%)and overall Kappa coefficients(0.76–0.95).The study revealed that megacities in the B&R region have undergone different types of urban sprawl,mainly adopting a‘concentric circle’pattern in inland areas and a‘sector’pattern in coastal areas.Besides,six expansion modes were summarized according to the AGRs of individual megacities.Differences existed in megacities of the developing and developed countries and among five sub-regions.Moreover,‘dispersion,gathering,and re-dispersion’and‘coalescence’were two major landscape patterns of megacities in developing and developed countries.Results of this study can provide a scientific reference for urban planning and aid in sustainable development of local areas.
文摘The authors regret that in 1.2.Instruments section of the article,when describing the principle of TiH300,the original content of“Briefly,ambient HONO was first absorbed by deionized water in a two-channel stripping coil.The absorbed liquid nitrite was mixed with sulfanilamide,N-(1-naphthyl)-ethylenediamine dihydrochloride,and hydrogen chloride solution to form the azo dye derivative.”
基金supported by the National Natural Science Foundation of China Fund(No.40975077)the National Natural Science Foundation of China and Guangdong Province Joint Fund(No.U1201232)
文摘Carbonyl-containing volatile organic compounds （cVOCs） are important precursors of atmospheric photochemical reactions in the formation of ozone, smog and other air pollutants. China＇s megacities are economically developed and densely populated metropolitan areas, usually with a population over ten million; they drive the rapid growth of surrounding urban clusters. So far, 21 cVOCs have been detected in the atmosphere of these megacities. The average annual total concentration of cVOCs is 55.6 μg/m^3, an alarmingly high level. Vehicle emissions, industrial discharges, excessive use of organic solvents and other factors have led to a situation where hazardous formaldehyde, acetaldehyde and acetone account for 62.4 percent of the total atmospheric concentration of cVOC in Chinese cities. In a quantitative evaluation using daily exposure levels, cancer risk and hazardquotient, we found that the excessive levels of atmospheric cVOCs in Beijing, Shanghai and Guangzhou pose serious health risks to their inhabitants. Air pollution persists, despite the brief improvements in air quality brought about by the air quality campaign undertaken during major intemational events like the 2008 Olympic Games, the 2010 Asian Games, and the 2010 World Expo. The health risks caused by atmospheric cVOCs in Chinese cities require close attention.
基金the National Key R&D plan on Strategic International Scientific and Technological Innovation Cooperation special project(2016YFE0202300)the Wuhan Chen Guang project(2016070204010114)+2 种基金the Guangzhou Science and Technology project(201604020070)the Special Task of Technical Innovation in Hubei Province project(2016AAA018)the Natural Science Foundation of China(61671332,41771452 and 41771454).
文摘Urbanization is one of the most important social and economic phenomena in the world today.This paper reviews the formation of megacities and summarizes the main problems,challenges and opportunities faced by the sustainable development of such large megacities.Issues discussed include the problems of land subsidence in megacities,environmental issues,traffic problems and energy supply aspects.The sustainable development of megacities in other parts of the world provided the references and experiences for the countermeasures of megacity planning and development in China.The vision of Digital Earth and Digital Cities can play a major role in the efficient management and sustainable growth of such megacities all around the world.
基金The Strategic Priority Research Program of Chinese Academy of Sciences,No.XDA20040403,No.XDA23100201。
文摘Megacities serve as global centers for economic,cultural,and high-tech industries.The structural features and population agglomerations are typical traits of urbanization,yet little is known about the morphological features and expansion patterns of megacities worldwide.Here we examined the spatiotemporal variations of urban land in megalopolises from 2000 to 2020 using the Urban Expansion Intensity Differentiation Index.The fractal features and expansion patterns of megacities were analyzed using the Area-Radius Multi-dimensional Scaling Model.Urban land use efficiency was then evaluated based on the linear relationship between urban land area and population.We found that Southeast Asia and China were the hotspots of urban expansion in megacities from 2000 to 2020,with urban land areas expanding by 3148.32 km^(2)and 5996.26 km^(2),respectively.The morphological features and expansion patterns of megacities exhibited a growing trend towards intensification and compactness,with the average radial dimension increasing from 1.54 to 1.56.The annual decrease in fractal dimensions indicated the integration of inner urban areas.North America and Europe megacities showed a low urban land use efficiency,with a ratio of urban land area to population ranging from 0.89 to 4.11 in 2020.Conversely,South Asia and Africa megacities exhibited a high urban land use efficiency,with the ratios between 0.23 and 0.87.Our results provide information for promoting efficient urban land utilization and sustainable cities.It is proposed to control the scale of urban expansion and to promote balanced development between inner and outer urban areas for achieving resilient and sustainable urban development.
文摘Several factors may contribute to on-going challenges for spatial planning and policy in megacities such as Rome, including rapid population shifts, poorly organized areas, and lack of data through which monitoring urban growth and land use change. This research was conducted to examine past and current effects of the urbanization process, occurred over the large Roman urban system, on the basis of multi-source and multi-temporal optical remote sensing (RS) data, collected between 1990 and 2013. These changes were then validated via Geographic Information System (GIS) techniques, in a particular procedure applied to urban land/agricultural transformations. The proposed approach, based on geo-statistical methods, was used to calculate the index of innovative space (AP Index), useful for the monitoring of the urban sprawl phenomenon. Strong evidence of urban expansion over the north-eastern quarter of the city, accompanied by environmental degradation and loss of biodiversity, is provided. Urban infill developments are expected to emerge in the south-eastern areas too, and these might increase urban pressure as well. In conclusion, RS and GIS technologies together with ancillary data can be used to assist decision makers in preparing future plans to find out appropriate solutions to urbanization encroachment.
文摘Adaptation is the pursuit of active, deliberate measures to enhance humankind’s capacity to manage water supply and attenuate demand in the face of climate uncertainty. This article contends that worsening constraints upon freshwater due to climate variability demand concerted, imaginative, science-based solutions. These solutions must join creative management to co-production of climate knowledge. Through a series of case studies, we analyze the need for adaptation approaches to prevail over climate variability, and the role of these factors to facilitate their implementation. We also examine how translation of climate knowledge is helping spur adaptation at various spatial levels. These experiences point to the challenges in adaptation, and the adversity various regions will be faced if we do not.
基金supported by General Project of National Social Science Fund[Grant number.22BZZ077],Study on Efficiency Improvement Mechanism of Rural Relative Poverty Governance Driven by Big Data.
文摘The transformation of Chengdu Tianfu New Area,a state-level new district,from the first site of constructing the“Park City”to the representative of the“Park City”,contains a unique path of“Chinese Style Governance”.To expand the diverse paths of constructing megacities,the current research references the nudge theory of behavioral science,adopts the extended case method,and takes Chengdu Tianfu New Area as a typical case to summarize the“nudge”path of“Party City”construction.The study found that the government achieves the lock-in effect by the priming mechanism and uses the nudge strategy of improving environment and guiding public opinion,thereby helping the people make free choices.It realizes the framework effect by the salience mechanism and uses the strategies of highlighting key information and optimizing information delivery methods,which directly affects the behavior of the public.It achieves the commitment effect by the comparison mechanism,including the horizontal comparison and vertical comparison strategies,and gradually realizes the policy goals.It realizes the social norm effect by the imitation mechanism and uses the strategies of creating peer pressure and playing celebrity effect,which in turn influence people’s choices.With the help of the“nudging”mechanism,the construction of the park city has realized the interactive cycle of“government output-citizen feedback”and achieved the goal of“making great change through small actions”.As a new behavioral intervention tool,“nudging”provides an alternative explanation for the construction of the park city in Tianfu New Area and opens up new ideas for the construction of megacities.This study concludes that the construction of megacities can achieve the goal of“common return”through different ways and provides practical inspiration for future urban construction.
基金The New Teachers＇ Scientific Research Program funded by Beijing Forestry University, No.BLX2013028 National Natural Science Foundation of China, No.41371166
文摘China has witnessed unprecedented urbanization over the past decades. The rapid expansion of urban population has been dominantly contributed by the floating population from rural areas, of which the spatiotemporal patterns, driving forces, and multidimensional effects are scrutinized and evaluated in this study by using the latest national censuses conducted in 2000 and 2010. Analysis based on the county-level data comes to conclusions as follows. The spatial pattern of floating population has remained stable over the first decade of the new century. The top 1% cities with the largest floating population received 45.5% of all migrants in China. As the rapid development of mega-city regions, the coastal concentration areas of floating population tended to geographically united as a whole, whereas the spatial distribution of migrants within each region varied significantly. The migrant concentration area in the Yangtze River Delta was the largest and its expansion was also the most salient. However, the floating population has growingly moved into provincial capitals and other big cities in the inland regions and its gravity center has moved northward for around 110 km during the study period. The spatial pattern of floating population has been formed jointly by the state and market forces in transitional China and the impacts of state forces have been surpassed by those of market forces in the country as a whole. The attractiveness of coastal cities and counties to the floating population comes mainly from the nonagricultural employment opportunities and public services, reflecting that long-distance and long-term migrants have moved coastward not only to gain employment but also to enjoy city life. By contrast, in the central and western regions, places with a higher economic development level and at a higher administrative level are more attractive to floating populations, demonstrating that the state remains to play an important role in allocating economic resources and promoting regional development in inland China. As the main body of new urban residents, the floating population has contributed substantially to the elevation of the urbanization levels of migrant-sending and -receiving places, by 20.0% and 49.5% respectively. Compared with ex- tensively investigated interprovincial migrants, intra-provincial migrants have higher intention and ability to permanently live in cities and thus might become the main force of China＇s urbanization in the coming decades. The internal migration has also reshaped China＇s urban system in terms of its hierarchical organization and spatial structure.
基金supported by the Tianjin Fundamental Research Program of the Tianjin Committee of Science and Technology (Grant No. 10JCYBJC050800)the National Special Science and Technology Program for Non-Profit Industry of the Ministry of Environmental Protection (Grant No. 200909022)+2 种基金the 973 Program (Grant No. 2011CB403402)the National Natural Science Foundation of China (NSFC) (Grant No. 40875001)the Basic Research Fund of the Chinese Academy of Meteorological Sciences (Grant No. 2008Z011)
文摘Tianjin is the third largest megacity and the fastest growth area in China,and consequently faces the problems of surface ozone and haze episodes.This study measures and characterizes volatile organic compounds （VOCs）,which are ozone precursors,to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin,China during the HaChi （Haze in China） summer campaign in 2009.A total of 107 species of ambient VOCs were detected,and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv,respectively.Of those,51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization.The identified sources of VOCs were significantly related to vehicular activities,which specifically contributed 60％ to urban and 42％ to suburban VOCs loadings in Tianjin.Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas,although the contribution of industry in the suburban area （36％） was much higher than that at the urban area （16％）.We conclude that controlling vehicle emissions should be a top priority for VOC reduction,and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life,especially in suburban areas.
