Guangzhou,a significant hub city in the Guangdong-Hong Kong-Macao Greater Bay Area,has seen fast social and economic growth as well as steady progress in the degree of urbanization.This research,taking Guangzhou city ...Guangzhou,a significant hub city in the Guangdong-Hong Kong-Macao Greater Bay Area,has seen fast social and economic growth as well as steady progress in the degree of urbanization.This research,taking Guangzhou city as an example,aims to provide an understanding of how land resources,urbanization,and spatial planning are coordinated in the study area.It also aims to explore how the coordination degree of land resources,urbanization,and spatial planning changes over time.It seeks to provide effective suggestions for land resource protection,national spatial planning,and urban transformation development to promote the coordinated development of the Guangdong-Hong Kong-Macao Greater Bay Area into a world-class Bay Area.展开更多
The inter-city linkage heat data provided by about:blank Migration is employed as a characterization of inter-city linkages in order to facilitate the study of the network linkage characteristics and hierarchical structure ...The inter-city linkage heat data provided by about:blank Migration is employed as a characterization of inter-city linkages in order to facilitate the study of the network linkage characteristics and hierarchical structure of urban agglomeration in the Greater Bay Area through the use of social network analysis method.This is the inaugural application of big data based on location services in the study of urban agglomeration network structure,which represents a novel research perspective on this topic.The study reveals that the density of network linkages in the Greater Bay Area urban agglomeration has reached 100%,indicating a mature network-like spatial structure.This structure has given rise to three distinct communities:Shenzhen-Dongguan-Huizhou,Guangzhou-Foshan-Zhaoqing,and Zhuhai-Zhongshan-Jiangmen.Additionally,cities within the Greater Bay Area urban agglomeration play different roles,suggesting that varying development strategies may be necessary to achieve staggered development.The study demonstrates that large datasets represented by LBS can offer novel insights and methodologies for the examination of urban agglomeration network structures,contingent on the appropriate mining and processing of the data.展开更多
The micaceous weathered granitic soil(WGS)is frequently encountered in civil engineering worldwide,unfortunately little information is available regarding how mica affects the physico-mechanical behaviors of WGS.This ...The micaceous weathered granitic soil(WGS)is frequently encountered in civil engineering worldwide,unfortunately little information is available regarding how mica affects the physico-mechanical behaviors of WGS.This study prepares reconstituted WGS with different mica contents by removing natural mica in theWGS,and then mixes it with commercial mica powders.The geotechnical behavior as well as the microstructures of the mixtures are characterized.The addition of mica enables the physical indices of WGS to be specific combinations of coarser gradation and high permeability but high Atterberg limits.However,high mica content in WGS was found to be associated with undesirable mechanical properties,including increased compressibility,disintegration,and swelling potential,as well as poor compactability and low effective frictional angle.Microstructural analysis indicates that the influence of mica on the responses of mixtures originates from the intrinsic nature of mica as well as the particle packing being formed withinWGS.Mica exists in the mixture as stacks of plates that form a spongy structure with high compressibility and swelling potential.Pores among the plates give the soil high water retention and high Atterberg limits.Large pores are also generated by soil particles with bridging packing,which enhances the permeability and water-soil interactions upon immersion.This study provides a microlevel understanding of how mica dominates the behavior of WGS and provides new insights into the effective stabilization and improvement of micaceous soils.展开更多
Snow water equivalent(SWE)is an important factor reflecting the variability of snow.It is important to estimate SWE based on remote sensing data while taking spatial autocorrelation into account.Based on the segmentat...Snow water equivalent(SWE)is an important factor reflecting the variability of snow.It is important to estimate SWE based on remote sensing data while taking spatial autocorrelation into account.Based on the segmentation method,the relationship between SWE and environmental factors in the central part of the Tibetan Plateau was explored using the eigenvector spatial filtering(ESF)regression model,and the influence of different factors on the SWE was explored.Three sizes of 16×16,24×24 and 32×32 were selected to segment raster datasets into blocks.The eigenvectors of the spatial adjacency matrix of the segmented size were selected to be added into the model as spatial factors,and the ESF regression model was constructed for each block in parallel.Results show that precipitation has a great influence on SWE,while surface temperature and NDVI have little influence.Air temperature,elevation and surface temperature have completely different effects in different areas.Compared with the ordinary least square(OLS)linear regression model,geographically weighted regression(GWR)model,spatial lag model(SLM)and spatial error model(SEM),ESF model can eliminate spatial autocorrelation with the highest accuracy.As the segmentation size increases,the complexity of ESF model increases,but the accuracy is improved.展开更多
Many countries in the world have experienced extremely rapid urbanization during recent decades. The rapiddevelopment of densely populated areas has produced many urban environmental problems. This researchexplores th...Many countries in the world have experienced extremely rapid urbanization during recent decades. The rapiddevelopment of densely populated areas has produced many urban environmental problems. This researchexplores the relationship between urban morphology and ventilation conditions. Through 3D modeling andComputational Fluid Dynamics (CFD) simulation, we focus on the large scale ventilation of an extended area withseveral buildings. As a testbed, in particular, the core part of Kwun Tong industrial park in Hong Kong is examined, and in order to validate the approach, 10 measurement points are used to get experimental values to be usedfor comparison (such points are located in different positions involving traffic road, pedestrian path and openspace). The error range (±0.7 m/s) indicates that the agreement between field measurement and CFD calculationis good. On the basis of design guidelines and earlier studies, the effective configuration (in terms of building) ofthis area is partially transformed (virtually, i.e., in the numerical simulations) in order to assess the ensuingchanges in terms of wind speed in different locations. This results in a general design and analysis methodologypotentially applicable to other areas.展开更多
Web maps represent an effective source for land cover mapping in capturing human activities.However,due to spatial heterogeneity,previous research has mainly focused on generating land cover maps in partial areas.Infe...Web maps represent an effective source for land cover mapping in capturing human activities.However,due to spatial heterogeneity,previous research has mainly focused on generating land cover maps in partial areas.Inferring spatial distribution patterns in Web maps may provide an alternative perspective on improving map production on a larger scale.This paper represents a novel approach to investigating the spatial distribution in Web maps for land cover mapping.First,linear features from Web maps are utilised to delineate parcels with insufficient Web map data for classification.Then,spatial factors are constructed from point and polygon features to identify the spatial variety of Web maps,with an artificial neural network classifier being adopted to classify land cover automatically.Land cover mapping is finally proposed by combining classified parcels and existing polygon features.The proposed method is applied in Guangzhou,Guangdong Province,using a Web map from AutoNavi.The results show an approximately 88%classification accuracy and an overall mapping accuracy of 85.06%.The results indicate that the proposed approach has the potential to be utilised in land cover mapping,and the constructed spatial factors are effective at characterising land cover information.展开更多
Health impact assessment (HIA) is an approach to identification of potential health benefits or hazards in urban planning schemes.Quantitative HIA provides uniform and comparable health outcomes (e.g.,the morbidity of...Health impact assessment (HIA) is an approach to identification of potential health benefits or hazards in urban planning schemes.Quantitative HIA provides uniform and comparable health outcomes (e.g.,the morbidity of a specific disease),which could effectively assist planning decisions.However,there are currently few quantitative HIA methods specifically for urban planning applications.Based on a review of existing HIA methods,this paper has developed a quantitative HIA system for urban planning schemes in China,and specifically evaluates health risks,health behaviors,and health outcomes.Taking the Territorial and Spatial Master Plan of the Gucun Township of Shanghai as an example,we have illustrated how to evaluate the reduced health risks and increased health behaviors,as well as how to calculate changes in potential health outcomes in order to provide a reference for relevant HIA practices.展开更多
With the continued development of multiple Global Navigation Satellite Systems(GNSS)and the emergence of various frequencies,UnDifferenced and UnCombined(UDUC)data processing has become an increasingly attractive opti...With the continued development of multiple Global Navigation Satellite Systems(GNSS)and the emergence of various frequencies,UnDifferenced and UnCombined(UDUC)data processing has become an increasingly attractive option.In this contribution,we provide an overview of the current status of UDUC GNSS data processing activities in China.These activities encompass the formulation of Precise Point Positioning(PPP)models and PPP-Real-Time Kinematic(PPP-RTK)models for processing single-station and multi-station GNSS data,respectively.Regarding single-station data processing,we discuss the advancements in PPP models,particularly the extension from a single system to multiple systems,and from dual frequencies to single and multiple frequencies.Additionally,we introduce the modified PPP model,which accounts for the time variation of receiver code biases,a departure from the conventional PPP model that typically assumes these biases to be time-constant.In the realm of multi-station PPP-RTK data processing,we introduce the ionosphere-weighted PPP-RTK model,which enhances the model strength by considering the spatial correlation of ionospheric delays.We also review the phase-only PPP-RTK model,designed to mitigate the impact of unmodelled code-related errors.Furthermore,we explore GLONASS PPP-RTK,achieved through the application of the integer-estimable model.For large-scale network data processing,we introduce the all-in-view PPP-RTK model,which alleviates the strict common-view requirement at all receivers.Moreover,we present the decentralized PPP-RTK data processing strategy,designed to improve computational efficiency.Overall,this work highlights the various advancements in UDUC GNSS data processing,providing insights into the state-of-the-art techniques employed in China to achieve precise GNSS applications.展开更多
The development of the Guangdong-Hong Kong-Macao Greater Bay Area is an important part of China’s national strategy in the new era.This paper reviews the process of cross-border planning collaboration in this area,fr...The development of the Guangdong-Hong Kong-Macao Greater Bay Area is an important part of China’s national strategy in the new era.This paper reviews the process of cross-border planning collaboration in this area,from functional division to institutional coordination.However,this process is still constrained by problems such as having few platforms and channels of collaboration,too much reliance on the provincial government,limited measures of collaboration,and weak coordination on the issues concerning core interests.It argues that the orientation should be building an open collaboration framework with multi-party participation and the specific strategies should include establishing a multi-level and multi-party planning collaboration framework,promoting the planning integration of three metropolitan areas,co-building a unified international quality life circle,promoting the co-building and co-sharing of strategic areas,and exploring diversified measures of planning collaboration.展开更多
Opening windows in coach buses is a practical approach to improving natural ventilation and mitigating infection risk(IR).Due to human behavior and weather conditions,the intermittent window opening strategy(IWOS)is a...Opening windows in coach buses is a practical approach to improving natural ventilation and mitigating infection risk(IR).Due to human behavior and weather conditions,the intermittent window opening strategy(IWOS)is a more common practice than keeping windows constantly open.Despite its prevalence,there are no studies exploring IWOS specifically in vehicles.We employed indoor-outdoor coupled CFD simulations to assess the effects of various IWOS on pathogen-laden droplet(PLD)dispersion and IR in a coach bus that occurred a COVID-19 outbreak in Hunan,China.Results reveal that after ventilating through two skylights for 600–1800 s,opening front and rear windows(FW+RW)or FW with a wind catcher(FW+WCH)for just 40 s can reduce PLD concentration(Cave)to 5%of its initial level and the intake fraction of the infector’s neighbor(IFn)drops by 95%.Upon closing FW+RW or FW+WCH,Cave and IFn take over 580 s to return to the pre-opening level.Moreover,intermittent FW opening halves Cave and IFn within 7 min,but leads to rapid increases upon window closure.Therefore,opening FW+RW and FW+WCH intermittently have pronounced impacts on indoor PLD concentration and are applicable approaches to control respiratory disease transmission in vehicles.According to the inhaled viral dose,it is recommended to open windows when driving time is over 12 minutes to reduce infection risk.In scenarios like epidemiological surveys and risk assessments,where assessing passenger infection risk is vital,some behaviors of opening windows cannot be overlooked and necessitate extra attention.展开更多
Metro is an important form of public transport in Shanghai.Based on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with time.Then the...Metro is an important form of public transport in Shanghai.Based on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with time.Then the characteristics of travel time and surrounding land use are investigated for different types of stations to explore the relationship between urban land-use characteristics and travel activities reflected by passenger flow at metro stations.It is found that the passenger flow pattern of metro stations is closely related to the location conditions of stations and its surrounding land-use patterns.Based on various characteristics,285 metro stations are classified into four types,including residential-oriented stations,employmentoriented stations,employment-residence-oriented stations,and integrated functionaloriented stations,reflecting the interaction between spontaneous travel behavior and urban land-use characteristics and providing a reference for optimizing the urban functional structure and the spatial allocation of facilities.展开更多
In the era of stock planning,the renovation of old residential communities has become an important part of urban development in China.However,the renovation planning is difficult to implement.The paper points out thre...In the era of stock planning,the renovation of old residential communities has become an important part of urban development in China.However,the renovation planning is difficult to implement.The paper points out three main factors that affect the implementation of old residential community renovation under the current system:complex property right structure,multiple stakeholders,and lack of funds.Based on the concept of Low Impact Development,and with minimizing the impact as the goal,the paper proposes a new mode for the renovation of old residential communities:through an analysis on property rights and interest game in old residential communities,and according to cost estimation,priority should be given to renovating the public elements that neither involve property rights or core interests nor require too many funds,including public space,roads,supporting facilities,etc.,with community management to be properly improved.In the end,with the renovation of Quanyechang Community of Wuhan City as an example,the paper concludes that this renovation mode can not only meet the urgent needs for renovation,but is also easy to implement.展开更多
High-temperature and high-pressure(high-grade)metamorphic complexes of variable ages are common in the Central Asian orogenic belt(CAOB),and their precise geochronology and origin are essential to unravel the orogenic...High-temperature and high-pressure(high-grade)metamorphic complexes of variable ages are common in the Central Asian orogenic belt(CAOB),and their precise geochronology and origin are essential to unravel the orogenic architecture and crust-production rate of the CAOB.Hereby it is essential to differentiate between pre-orogenic Precambrian basement and Paleozoic arc-accretionary complexes.This study provides precise in situ zircon U-Pb ages for the metasedimentary rocks in the Wuwamen ophiolitic mélange,which is traditionally thought to represent the pre-orogenic basement of the southwestern CAOB.A meta-sandstone from the meta-flysch sequence revealed a widespread ca.1.8 Ga high-grade metamorphic overprint similar to that of the underlying orthogneisses and,thus,was interpreted to represent pre-orogenic basement fragments that occur as tectonic blocks in the Paleozoic ophiolitic mélange.In contrast,a schist from the mélange matrix is characterized by a ca.333 Ma high-grade metamorphic overprint,indicating that the northward subduction of the South Tianshan Ocean was still active at this time.The thrust-imbricated high-grade metamorphic rocks of contrasting origins in an accretionary complex have important implications for the understanding the accretionary history and crustal growth of the CAOB.Furthermore,the strongly deformed ophiolitic mélange was intruded by an undeformed granite dyke with an emplacement age younger than ca.294 Ma,thus providing a minimum age limit for the final closure of the South Tianshan Ocean.展开更多
Level set method has been extensively used for image segmentation,which is a key technology of water extraction.However,one of the problems of the level-set method is how to find the appropriate initial surface parame...Level set method has been extensively used for image segmentation,which is a key technology of water extraction.However,one of the problems of the level-set method is how to find the appropriate initial surface parameters,which will affect the accuracy and speed of level set evolution.Recently,the semantic segmentation based on deep learning has opened the exciting research possibilities.In addition,the Convolutional Neural Network(CNN)has shown a strong feature representation capability.Therefore,in this paper,the CNN method is used to obtain the initial SAR image segmentation map to provide deep a priori information for the zero-level set curve,which only needs to describe the general outline of the water body,rather than the accurate edges.Compared with the traditional circular and rectangular zero-level set initialization method,this method can converge to the edge of the water body faster and more precisely;it will not fall into the local minimum value and be able to obtain accurate segmentation results.The effectiveness of the proposed method is demonstrated by the experimental results of flood disaster monitoring in South China in 2020.展开更多
文摘Guangzhou,a significant hub city in the Guangdong-Hong Kong-Macao Greater Bay Area,has seen fast social and economic growth as well as steady progress in the degree of urbanization.This research,taking Guangzhou city as an example,aims to provide an understanding of how land resources,urbanization,and spatial planning are coordinated in the study area.It also aims to explore how the coordination degree of land resources,urbanization,and spatial planning changes over time.It seeks to provide effective suggestions for land resource protection,national spatial planning,and urban transformation development to promote the coordinated development of the Guangdong-Hong Kong-Macao Greater Bay Area into a world-class Bay Area.
文摘The inter-city linkage heat data provided by about:blank Migration is employed as a characterization of inter-city linkages in order to facilitate the study of the network linkage characteristics and hierarchical structure of urban agglomeration in the Greater Bay Area through the use of social network analysis method.This is the inaugural application of big data based on location services in the study of urban agglomeration network structure,which represents a novel research perspective on this topic.The study reveals that the density of network linkages in the Greater Bay Area urban agglomeration has reached 100%,indicating a mature network-like spatial structure.This structure has given rise to three distinct communities:Shenzhen-Dongguan-Huizhou,Guangzhou-Foshan-Zhaoqing,and Zhuhai-Zhongshan-Jiangmen.Additionally,cities within the Greater Bay Area urban agglomeration play different roles,suggesting that varying development strategies may be necessary to achieve staggered development.The study demonstrates that large datasets represented by LBS can offer novel insights and methodologies for the examination of urban agglomeration network structures,contingent on the appropriate mining and processing of the data.
基金The financial supports of the National Natural Science Foundation of China(Grant No.42177148)the opening fund of State Key Laboratory of Geohazard Prevention and Geo-environment Protection(Grant No.SKLGP 2023K011)Postdoctoral Research Project of Guangzhou(Grant No.20220402)are gratefully thanked.
文摘The micaceous weathered granitic soil(WGS)is frequently encountered in civil engineering worldwide,unfortunately little information is available regarding how mica affects the physico-mechanical behaviors of WGS.This study prepares reconstituted WGS with different mica contents by removing natural mica in theWGS,and then mixes it with commercial mica powders.The geotechnical behavior as well as the microstructures of the mixtures are characterized.The addition of mica enables the physical indices of WGS to be specific combinations of coarser gradation and high permeability but high Atterberg limits.However,high mica content in WGS was found to be associated with undesirable mechanical properties,including increased compressibility,disintegration,and swelling potential,as well as poor compactability and low effective frictional angle.Microstructural analysis indicates that the influence of mica on the responses of mixtures originates from the intrinsic nature of mica as well as the particle packing being formed withinWGS.Mica exists in the mixture as stacks of plates that form a spongy structure with high compressibility and swelling potential.Pores among the plates give the soil high water retention and high Atterberg limits.Large pores are also generated by soil particles with bridging packing,which enhances the permeability and water-soil interactions upon immersion.This study provides a microlevel understanding of how mica dominates the behavior of WGS and provides new insights into the effective stabilization and improvement of micaceous soils.
基金funded by the National Key S&T Special Projects of China(grant number:2018YFB0505302)the National Nature Science Foundation of China(grant number:41671380)。
文摘Snow water equivalent(SWE)is an important factor reflecting the variability of snow.It is important to estimate SWE based on remote sensing data while taking spatial autocorrelation into account.Based on the segmentation method,the relationship between SWE and environmental factors in the central part of the Tibetan Plateau was explored using the eigenvector spatial filtering(ESF)regression model,and the influence of different factors on the SWE was explored.Three sizes of 16×16,24×24 and 32×32 were selected to segment raster datasets into blocks.The eigenvectors of the spatial adjacency matrix of the segmented size were selected to be added into the model as spatial factors,and the ESF regression model was constructed for each block in parallel.Results show that precipitation has a great influence on SWE,while surface temperature and NDVI have little influence.Air temperature,elevation and surface temperature have completely different effects in different areas.Compared with the ordinary least square(OLS)linear regression model,geographically weighted regression(GWR)model,spatial lag model(SLM)and spatial error model(SEM),ESF model can eliminate spatial autocorrelation with the highest accuracy.As the segmentation size increases,the complexity of ESF model increases,but the accuracy is improved.
文摘Many countries in the world have experienced extremely rapid urbanization during recent decades. The rapiddevelopment of densely populated areas has produced many urban environmental problems. This researchexplores the relationship between urban morphology and ventilation conditions. Through 3D modeling andComputational Fluid Dynamics (CFD) simulation, we focus on the large scale ventilation of an extended area withseveral buildings. As a testbed, in particular, the core part of Kwun Tong industrial park in Hong Kong is examined, and in order to validate the approach, 10 measurement points are used to get experimental values to be usedfor comparison (such points are located in different positions involving traffic road, pedestrian path and openspace). The error range (±0.7 m/s) indicates that the agreement between field measurement and CFD calculationis good. On the basis of design guidelines and earlier studies, the effective configuration (in terms of building) ofthis area is partially transformed (virtually, i.e., in the numerical simulations) in order to assess the ensuingchanges in terms of wind speed in different locations. This results in a general design and analysis methodologypotentially applicable to other areas.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.41501420,41301377).
文摘Web maps represent an effective source for land cover mapping in capturing human activities.However,due to spatial heterogeneity,previous research has mainly focused on generating land cover maps in partial areas.Inferring spatial distribution patterns in Web maps may provide an alternative perspective on improving map production on a larger scale.This paper represents a novel approach to investigating the spatial distribution in Web maps for land cover mapping.First,linear features from Web maps are utilised to delineate parcels with insufficient Web map data for classification.Then,spatial factors are constructed from point and polygon features to identify the spatial variety of Web maps,with an artificial neural network classifier being adopted to classify land cover automatically.Land cover mapping is finally proposed by combining classified parcels and existing polygon features.The proposed method is applied in Guangzhou,Guangdong Province,using a Web map from AutoNavi.The results show an approximately 88%classification accuracy and an overall mapping accuracy of 85.06%.The results indicate that the proposed approach has the potential to be utilised in land cover mapping,and the constructed spatial factors are effective at characterising land cover information.
基金supported by the General Program of the National Natural Science Foundation of China(No.52078349)the 2020 Program of the Science and Technology Commission of Shanghai Municipality(No.20DZ1201702)。
文摘Health impact assessment (HIA) is an approach to identification of potential health benefits or hazards in urban planning schemes.Quantitative HIA provides uniform and comparable health outcomes (e.g.,the morbidity of a specific disease),which could effectively assist planning decisions.However,there are currently few quantitative HIA methods specifically for urban planning applications.Based on a review of existing HIA methods,this paper has developed a quantitative HIA system for urban planning schemes in China,and specifically evaluates health risks,health behaviors,and health outcomes.Taking the Territorial and Spatial Master Plan of the Gucun Township of Shanghai as an example,we have illustrated how to evaluate the reduced health risks and increased health behaviors,as well as how to calculate changes in potential health outcomes in order to provide a reference for relevant HIA practices.
基金National Natural Science Foundation of China(No.42022025)。
文摘With the continued development of multiple Global Navigation Satellite Systems(GNSS)and the emergence of various frequencies,UnDifferenced and UnCombined(UDUC)data processing has become an increasingly attractive option.In this contribution,we provide an overview of the current status of UDUC GNSS data processing activities in China.These activities encompass the formulation of Precise Point Positioning(PPP)models and PPP-Real-Time Kinematic(PPP-RTK)models for processing single-station and multi-station GNSS data,respectively.Regarding single-station data processing,we discuss the advancements in PPP models,particularly the extension from a single system to multiple systems,and from dual frequencies to single and multiple frequencies.Additionally,we introduce the modified PPP model,which accounts for the time variation of receiver code biases,a departure from the conventional PPP model that typically assumes these biases to be time-constant.In the realm of multi-station PPP-RTK data processing,we introduce the ionosphere-weighted PPP-RTK model,which enhances the model strength by considering the spatial correlation of ionospheric delays.We also review the phase-only PPP-RTK model,designed to mitigate the impact of unmodelled code-related errors.Furthermore,we explore GLONASS PPP-RTK,achieved through the application of the integer-estimable model.For large-scale network data processing,we introduce the all-in-view PPP-RTK model,which alleviates the strict common-view requirement at all receivers.Moreover,we present the decentralized PPP-RTK data processing strategy,designed to improve computational efficiency.Overall,this work highlights the various advancements in UDUC GNSS data processing,providing insights into the state-of-the-art techniques employed in China to achieve precise GNSS applications.
文摘The development of the Guangdong-Hong Kong-Macao Greater Bay Area is an important part of China’s national strategy in the new era.This paper reviews the process of cross-border planning collaboration in this area,from functional division to institutional coordination.However,this process is still constrained by problems such as having few platforms and channels of collaboration,too much reliance on the provincial government,limited measures of collaboration,and weak coordination on the issues concerning core interests.It argues that the orientation should be building an open collaboration framework with multi-party participation and the specific strategies should include establishing a multi-level and multi-party planning collaboration framework,promoting the planning integration of three metropolitan areas,co-building a unified international quality life circle,promoting the co-building and co-sharing of strategic areas,and exploring diversified measures of planning collaboration.
基金supported by the National Natural Science Foundation of China(No.42175095,No.42005069,and No.42175180)support from Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004,2021B0301030007)the UK GCRF Rapid Response Grant on“Transmission of SARS-CoV-2 virus in crowded indoor environment”,and the Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.311020001)are also gratefully acknowledged.
文摘Opening windows in coach buses is a practical approach to improving natural ventilation and mitigating infection risk(IR).Due to human behavior and weather conditions,the intermittent window opening strategy(IWOS)is a more common practice than keeping windows constantly open.Despite its prevalence,there are no studies exploring IWOS specifically in vehicles.We employed indoor-outdoor coupled CFD simulations to assess the effects of various IWOS on pathogen-laden droplet(PLD)dispersion and IR in a coach bus that occurred a COVID-19 outbreak in Hunan,China.Results reveal that after ventilating through two skylights for 600–1800 s,opening front and rear windows(FW+RW)or FW with a wind catcher(FW+WCH)for just 40 s can reduce PLD concentration(Cave)to 5%of its initial level and the intake fraction of the infector’s neighbor(IFn)drops by 95%.Upon closing FW+RW or FW+WCH,Cave and IFn take over 580 s to return to the pre-opening level.Moreover,intermittent FW opening halves Cave and IFn within 7 min,but leads to rapid increases upon window closure.Therefore,opening FW+RW and FW+WCH intermittently have pronounced impacts on indoor PLD concentration and are applicable approaches to control respiratory disease transmission in vehicles.According to the inhaled viral dose,it is recommended to open windows when driving time is over 12 minutes to reduce infection risk.In scenarios like epidemiological surveys and risk assessments,where assessing passenger infection risk is vital,some behaviors of opening windows cannot be overlooked and necessitate extra attention.
文摘Metro is an important form of public transport in Shanghai.Based on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with time.Then the characteristics of travel time and surrounding land use are investigated for different types of stations to explore the relationship between urban land-use characteristics and travel activities reflected by passenger flow at metro stations.It is found that the passenger flow pattern of metro stations is closely related to the location conditions of stations and its surrounding land-use patterns.Based on various characteristics,285 metro stations are classified into four types,including residential-oriented stations,employmentoriented stations,employment-residence-oriented stations,and integrated functionaloriented stations,reflecting the interaction between spontaneous travel behavior and urban land-use characteristics and providing a reference for optimizing the urban functional structure and the spatial allocation of facilities.
文摘In the era of stock planning,the renovation of old residential communities has become an important part of urban development in China.However,the renovation planning is difficult to implement.The paper points out three main factors that affect the implementation of old residential community renovation under the current system:complex property right structure,multiple stakeholders,and lack of funds.Based on the concept of Low Impact Development,and with minimizing the impact as the goal,the paper proposes a new mode for the renovation of old residential communities:through an analysis on property rights and interest game in old residential communities,and according to cost estimation,priority should be given to renovating the public elements that neither involve property rights or core interests nor require too many funds,including public space,roads,supporting facilities,etc.,with community management to be properly improved.In the end,with the renovation of Quanyechang Community of Wuhan City as an example,the paper concludes that this renovation mode can not only meet the urgent needs for renovation,but is also easy to implement.
基金financially supported by the National Natural Science Foundation of China(Nos.42072079,42172234,41902232)China Geological Survey(No.DD20190060)。
文摘High-temperature and high-pressure(high-grade)metamorphic complexes of variable ages are common in the Central Asian orogenic belt(CAOB),and their precise geochronology and origin are essential to unravel the orogenic architecture and crust-production rate of the CAOB.Hereby it is essential to differentiate between pre-orogenic Precambrian basement and Paleozoic arc-accretionary complexes.This study provides precise in situ zircon U-Pb ages for the metasedimentary rocks in the Wuwamen ophiolitic mélange,which is traditionally thought to represent the pre-orogenic basement of the southwestern CAOB.A meta-sandstone from the meta-flysch sequence revealed a widespread ca.1.8 Ga high-grade metamorphic overprint similar to that of the underlying orthogneisses and,thus,was interpreted to represent pre-orogenic basement fragments that occur as tectonic blocks in the Paleozoic ophiolitic mélange.In contrast,a schist from the mélange matrix is characterized by a ca.333 Ma high-grade metamorphic overprint,indicating that the northward subduction of the South Tianshan Ocean was still active at this time.The thrust-imbricated high-grade metamorphic rocks of contrasting origins in an accretionary complex have important implications for the understanding the accretionary history and crustal growth of the CAOB.Furthermore,the strongly deformed ophiolitic mélange was intruded by an undeformed granite dyke with an emplacement age younger than ca.294 Ma,thus providing a minimum age limit for the final closure of the South Tianshan Ocean.
基金supported by the National Natural Science Foundation of China[grant numbers 41771457 and 41601443]the Research Program of the Department of Natural Resources of Hubei Province of China[grant number ZRZY2020KJ03].
文摘Level set method has been extensively used for image segmentation,which is a key technology of water extraction.However,one of the problems of the level-set method is how to find the appropriate initial surface parameters,which will affect the accuracy and speed of level set evolution.Recently,the semantic segmentation based on deep learning has opened the exciting research possibilities.In addition,the Convolutional Neural Network(CNN)has shown a strong feature representation capability.Therefore,in this paper,the CNN method is used to obtain the initial SAR image segmentation map to provide deep a priori information for the zero-level set curve,which only needs to describe the general outline of the water body,rather than the accurate edges.Compared with the traditional circular and rectangular zero-level set initialization method,this method can converge to the edge of the water body faster and more precisely;it will not fall into the local minimum value and be able to obtain accurate segmentation results.The effectiveness of the proposed method is demonstrated by the experimental results of flood disaster monitoring in South China in 2020.
