Farmland transfer is an important land policy for reducing agricultural fragmentation and improving land use efficiency.Many studies have investigated the driving forces of farmland transfer at the farmers’scale.Howe...Farmland transfer is an important land policy for reducing agricultural fragmentation and improving land use efficiency.Many studies have investigated the driving forces of farmland transfer at the farmers’scale.However,the overall spatial distribution and driving mechanisms of farmland transfer at the county scale has been less quantified.In this study,we evaluated farmland transfer and its spatial pattern in Central Yunnan Urban Agglomeration(CYUA)of China by using statistical data at the county scale in 2020.A so-cial-ecological indicator system,comprising natural endowment,social indicators,economic indicators,and landscape patterns,was es-tablished to explore the relationship between farmland transfer and its driving factors.Additionally,a heuristic structural equation mod-el(SEM)was employed to disentangle direct and indirect drivers of farmland transfer.The results indicated that significant spatial clusters of farmland transfer,with high transfer rates concentrated in highly urbanized areas and low transfer rates prevalent in tradition-al ethnic minority regions.Farmland transfer is primarily driven by soil quality,landscape patterns,terrain,and social-economic rurality.Specifically,higher soil quality and improved landscape connectivity facilitate farmland transfer directly,while gentler slopes promote farmland transfer indirectly by supporting better educational opportunities and fewer minority population.Improving rural vocational training and optimizing landscape patterns through land consolidation and redistribution are important in the mountainous areas.This study can provide valuable analytical framework for farmland management for other mountainous regions.展开更多
Patna is among the cities high populated at risk of ecological and environmental deterioration due to a variety of human activities,such as poor land cover management.One of the most crucial elements of a successful l...Patna is among the cities high populated at risk of ecological and environmental deterioration due to a variety of human activities,such as poor land cover management.One of the most crucial elements of a successful land resource management plan is the evaluation of Land Use Land Cover(LULC).Over the past 20 years,our planet’s land cover resources have undergone substantial changes due to rapid development.The Land Use Land Cover(LULC)categories of the Patna Urban Agglomeration(PUA),including water bodies,agricultural land,barren land,built-up areas,and vegetation,were identified using Geographic Information System(GIS)techniques.Three multi-temporal images were analyzed and classified through supervised classification using the maximum likelihood method.By comparing three separately created LULC categorized maps from 1990 and 2024,temporal changes were analyzed.In order to update land cover or manage natural resources,it is vital to use change detection as a tool to identify changes in LULC over time in PUA,Patna between 1990,2010 and 2024.According to their respective Kappa coefficients,the accuracy rates for 1990,2010 and 2024 LULC are 91.66 and 94.93,respectively.An accuracy evaluation was conducted to determine the correctness of the classification system and to determine the efficacy of the LULC classification maps.One hundred reference test pixels were identified.There have been found significant changes in the LULC were built up area has increased doubled in last thirty-four years of timeline.展开更多
Majority of carbon emissions originate from fossil energy consumption,thus necessitating calculation and monitoring of carbon emissions from energy consumption.In this study,we utilized energy consumption data from Si...Majority of carbon emissions originate from fossil energy consumption,thus necessitating calculation and monitoring of carbon emissions from energy consumption.In this study,we utilized energy consumption data from Sichuan Province and Chongqing Municipality for the years 2000 to 2019 to estimate their statistical carbon emissions.We then employed nighttime light data to downscale and infer the spatial distribution of carbon emissions at the county level within the Chengdu-Chongqing urban agglomeration.Furthermore,we analyzed the spatial pattern of carbon emissions at the county level using the coefficient of variation and spatial autocorrelation,and we used the Geographically and Temporally Weighted Regression(GTWR)model to analyze the influencing factors of carbon emissions at this scale.The results of this study are as follows:(1)from 2000 to 2019,the overall carbon emissions in the Chengdu-Chongqing urban agglomeration showed an increasing trend followed by a decrease,with an average annual growth rate of 4.24%.However,in recent years,it has stabilized,and 2012 was the peak year for carbon emissions in the Chengdu-Chongqing urban agglomeration;(2)carbon emissions exhibited significant spatial clustering,with high-high clustering observed in the core urban areas of Chengdu and Chongqing and low-low clustering in the southern counties of the Chengdu-Chongqing urban agglomeration;(3)factors such as GDP,population(Pop),urbanization rate(Ur),and industrialization structure(Ic)all showed a significant influence on carbon emissions;(4)the spatial heterogeneity of each influencing factor was evident.展开更多
This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking an...This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking and neutrality goals.This research ana-lyzes the spatial characteristics of carbon metabolism from 2000 to 2020 and uses models to identify stable carbon sink areas,positive carbon flow corridors,and carbon sequestration nodes.The goal is to construct a carbon metabolism spatial security pattern(CMSSP)and propose territorial ecological restoration strategies under different development demand scenarios.The results show the following:1)in 2020,the study area’s carbon sink decreased by 8.29×10^(4) t C/yr compared with that in 2010 and by 10.83×10^(4) t C/yr compared with that in 2000.High-carbon sinks were found mainly in mountainous areas,whereas low-carbon sinks are concentrated in urban con-struction land,rural residential areas,and land margins.2)From 2000 to 2020,the spatial security pattern of carbon metabolism tended to be‘high in the middle of the east and west and low in the gulf.’In 2000,2010,and 2020,16 stable carbon sinks were identified.The carbon energy flow density in Guangxi was greater than that in Guangdong and Hainan,with positive carbon flow corridors located primarily in Guangxi and Guangdong.The number of carbon sequestration nodes remained stable at approximately 15,mainly in Guangxi and Hainan.3)Scenario simulations revealed that under the Nature-based mild restoration scenario,the carbon sink rate will reach 611.85×10^(4) t C/yr by 2030 and increase to 612.45×10^(4) t C/yr by 2060,with stable carbon sinks increasing to 18.In the restora-tion scenario based on Anti-globalization,the carbon sink will decrease from 610.24×10^(4) t C/yr in 2030 to 605.19×10^(4) t C/yr in 2060,with the disappearance of some positive carbon flow corridors and stable carbon sinks.Under the Human-based sustainable restoration scenario,the carbon sink area will decrease from 607.00×10^(4) t C/yr in 2030 to 596.39×10^(4) t C/yr in 2060,with carbon sink areas frag-menting and positive carbon flow corridors becoming less dense.4)On the basis of the current and predicted CMSSPs,this study ex-plores spatial ecological restoration strategies for high-carbon storage areas in bay urban agglomerations at four levels:the land control region,urban agglomeration structure system,carbon sink structure and bay structure control region.展开更多
AP(Ammonium Perchlorate)and HMX(Octogen)are the two oxidizers most often used in Nitrate-Ester-Plasticized Polyether(NEPE)rocket propellants.How the AP–HMX ratio influences the agglomeration of NEPE propellants remai...AP(Ammonium Perchlorate)and HMX(Octogen)are the two oxidizers most often used in Nitrate-Ester-Plasticized Polyether(NEPE)rocket propellants.How the AP–HMX ratio influences the agglomeration of NEPE propellants remains unclear.We experimentally investigated the effect of the AP–HMX ratio on the combustion and agglomeration of NEPE propellants using burning rate test,quenched surface analysis,microscopic observations,and the collection of condensed combustion products.It was found that with the decrease in AP content from 40wt%to 10wt%,the burning rate decreased from 14.2 mm/s to 9.2 mm/s because the adiabatic flame temperature of NEPE propellants decreased from 3828 K to 3736 K.Pockets bounded by AP particles appeared on the surface when AP content was 40wt%;however,the accumulations grew and covered the burning surface eventually as the AP–HMX ratio decreased.The time required for the accumulation to coalesce into agglomerates increased with decreasing AP content.Even with similar agglomerate sizes,the coalescence time increased by 83%when the AP content decreased from 40wt%to 30wt%.The agglomerate size in the Condensed Combustion Products(CCPs)increased from 100μm to 200μm,and the fraction of large agglomerations increased from 6.4%to 24.7%when the AP content decreased from 40wt%to 10wt%.Overall,the high flame temperature of the AP particles enhanced the decomposition of the surrounding binder,resulting in the rapid ejection of the aluminum particles into the gas,which had a separating effect on the accumulation,thus weakening the agglomeration.展开更多
Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of dif...Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of different Ti and Al contents on the agglomeration behavior of non-metallic inclusions in low carbon steels.Furthermore,the agglomeration mechanism of inclusions was investigated through quantitative analysis of in-situ observation experiments and a modified Kralchevsky-Paunov model.The obtained results indicate that Al_(2)O_(3)is the main type inclusion in the low-alloys steels with both Al and Ti addition.This type of inclusion is more likely to absorb surrounding small-size inclusion particles,leading to a further growth for the cluster formation and contributing to a serious engineering problem,nozzle clogging.Besides,TiO_(x)is the main type inclusion in the molten steel with only Ti addition,and this type of inclusion is less likely to agglomerate and the individual inclusion particles show a‘free’motion with the fluid of molten steel.The difference between these two types of inclusions is due to the difference in attractive force and action distance at the meniscus created by the inclusion/steel/Ar multiple interfaces and influenced by the physical parameters,e.g.,contact angle and interface energy between inclusion and steel,and surface tension of the melt.展开更多
The formation of large-sized inclusions cluster severely impacts the continuous casting process and product quality of titanium-containing steel.Thermodynamic calculations were initially conducted to predict the forma...The formation of large-sized inclusions cluster severely impacts the continuous casting process and product quality of titanium-containing steel.Thermodynamic calculations were initially conducted to predict the formation of various complex oxide inclusions,namely Al_(2)O_(3),TiO_(x)and Al-Ti-O.Based on that,laboratory-scale experiments were designed to prepare samples with a single type of inclusions.Then,the scanning electron microscope-energy dispersive spectrometer was used for quantitative characterization.Subsequently,the agglomeration behavior of inclusions in Fe-Al-Ti-O melt was observed in situ by high-temperature confocal laser scanning microscopy.Furthermore,a quantitative analysis of the agglomeration characteristics of the various inclusions was conducted based on the attractive forces in accordance with Newton's second law and the capillary forces as described by the Kralchevsky-Paunov model.The results indicate that the size of Al_(2)O_(3)inclusions is larger than that of TiO_(x)and Al-Ti-O,but the number density of TiO_(x)is the highest.Based on the in situ observation and the theoretical calculation,Al_(2)O_(3),TiO_(x)and Al-Ti-O inclusions can all agglomerate into large-sized clusters without segregation,but the agglomeration tendency of Al_(2)O_(3)and TiO_(x)is stronger than that of Al-Ti-O.The attractive force between Al_(2)O_(3)inclusions’pair is the largest,ranging from 2.26×10^(-15)to 6.12×10^(-14)N,followed by TiO_(x)(7.13×10^(-16)to 3.56×10^(-14)N)and Al-Ti-O(1.16×10^(-17)to 3.77×10^(-16)N).展开更多
This study determines whether industrial agglomeration can solve energy poverty(ENPO)by applying a provincial dataset(2002-2019)to assess the potential effect of industrial agglomeration on ENPO.Additionally,this stud...This study determines whether industrial agglomeration can solve energy poverty(ENPO)by applying a provincial dataset(2002-2019)to assess the potential effect of industrial agglomeration on ENPO.Additionally,this study conducts an in-depth exploration of provincial heterogeneity and its influence mechanisms.The conclusions are as follows:①Industrial agglomeration is negatively correlated with ENPO;by implication,enhancing industrial agglomeration is a driving force for reducing ENPO.②The alleviating effect of industrial agglomeration on ENPO in the midwestern region is considerably higher than that in the eastern region,and the ENPO alleviation effect of the high agglomeration region is better than that in the low agglomeration region.③Foreign investment and energy efficiency have a mediating role,that is,they are valid transmission pathways for industrial agglomeration to solve the ENPO issue.Relevant policy suggestions for reducing ENPO by accelerating industrial agglomeration are proposed by drawing on the above three conclusions.展开更多
Research on urban health constitutes an important issue in the field of health geography and also a strong propeller of the Healthy China Initiative.As the main form that realizes new-type urbanization,urban agglomera...Research on urban health constitutes an important issue in the field of health geography and also a strong propeller of the Healthy China Initiative.As the main form that realizes new-type urbanization,urban agglomerations should become the primal sites for the construction of a“Healthy China”.The evaluation of healthy cities’development in urban agglomerations has both theoretical and practical values.Based on the concept of urban health and its evaluation models,this paper developed an evaluation framework for healthy cities that involved multiple data sources.With 19 urban agglomerations in China as the research subjects,we used CRITIC weighting and geographical detectors to examine the geographies of healthy cities and their influencing factors in 2010 and 2020.The results were fourfold.Firstly,the urban health level of China significantly increased from 2010 to 2020,and the comprehensive health index developed towards a positive skewed distribution,along with a shift from“low in the hinterland-high in the coastal areas”to a“multipolar”pattern led by the coastal and southwest urban agglomerations.Secondly,among various dimensions of urban health,the healthy environment index became improved with narrowed regional differences;while the health services index was still polarized;health collaboration was upgraded with a strengthened intercity health network;the healthy population index slightly declined and converged to the middle.Thirdly,urban health in China has initially demonstrated the characteristics of a H-H pattern in the Yangtze River Delta and ChengduChongqing regions,as well as L-L clusters in the northern urban agglomerations,the narrowed regional differences,and increasing coordination within each urban agglomeration.Fourthly,the geographical detector found that economy,urbanization and the human capital were significant external factors that affected urban health development.The explanatory power of technological innovation and opening to the outside world were also increasing.The development of healthy cities is yet to be transformed into regional health integration.展开更多
Dryland regions face complex interactions between urbanization and ecological changes,where effective coordination is essential for enhancing sustainability and resilience.However,most studies concentrate on the natio...Dryland regions face complex interactions between urbanization and ecological changes,where effective coordination is essential for enhancing sustainability and resilience.However,most studies concentrate on the national or provincial scales,with insufficient research on county-level coordination,limiting the ability to provide targeted polifrom a precise perspective.This study addresses this gap by analyzing 39 counties within the Hohhot-Baotou-Ordos-Yulin Urban Agglomeration(HBOYUA),a typical dryland urban cluster in China.We use daytime and nighttime remote sensing images to track the spatio-temporal evolution of urbanization and ecological conditions from 1992 to 2023.A novel quantitative framework based on an improved coupling coordination degree(CCD)is proposed to assess their coordination relationship.The results reveal that:(1)Urbanization and ecological quality both exhibited fluctuating upward trends,with spatial heterogeneity increasing for urbanization and decreasing for the eco-environment.Regions with better ecological conditions had higher urbanization levels.(2)The overall coordinated level improved from imbalance(0.36)to low-level coordination(0.55),although its spatial distribution remained uneven,with central urban areas showing higher CCD than surrounding counties.(3)Socioeconomic factors exerted greater effects on CCD than natural factors,with GDP and land surface temperature(LST)playing a significant role in interaction analysis.(4)In western arid regions,urbanization did not necessarily harm ecosystems;instead,ecological conditions improved alongside urbanization.This research offers targeted and valuable references for county and city governments in resource allocation and sustainable development.The proposed methodology is also adaptable for urban resilience studies in other regions.展开更多
Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking wa...Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks.In this study,tapwater(TW)and bottledwater(BW)sampleswere collected from eight cities in the Yangtze River Delta urban agglomeration in China,and their OAP levelswere analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction(Hi-throat/Hi-volume SPE techniques).This study is the first to systematically characterize the trace levels of OAPs in drinking water in China.Our findings indicated that the total concentration of OAPs(OAPs)in TW(average 11.06±4.99 ng/L)was 29.4%higher than in BW(average 8.55±3.98 ng/L)and fewer kinds(7)of OAPs were detected in BW.Furthermore,the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range,particularly in males,with molinate being the major contributor(61.3%)to OAP exposure.Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants(DWTPs).Furthermore,our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water(up to 87.5%).Therefore,our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.展开更多
In the context of China’ s dual carbon goals, transforming traditional manufacturing agglomeration into green manufacturing agglomeration is pivotal in aligning economic development with environmental protection, ult...In the context of China’ s dual carbon goals, transforming traditional manufacturing agglomeration into green manufacturing agglomeration is pivotal in aligning economic development with environmental protection, ultimately contributing to the country’ s high-quality economic growth. This study examines the dynamic nonlinear effects of manufacturing agglomeration on economic development, energy consumption, environmental pollution, and green total factor productivity. We developed a theoretical framework that considered local government constraints and incentives as transition variables and employed panel data from 280 cities at or above the prefecture level in China from 2006 to 2020 using a Panel Smooth Transition Regression model. The results reveal that, first, under both constraints and incentives, a single threshold effect exists beyond which the positive impact of manufacturing agglomeration on economic development, energy consumption, and environmental pollution gradually weakens. Second, the spatiotemporal evolution of manufacturing agglomeration shows that traditional manufacturing agglomerations are gradually spreading from the central and western regions to the resourcebased regions in the eastern part of the country, while green manufacturing agglomerations are shrinking annually. Third, a comparative analysis indicates that, in both developed and developing countries, manufacturing agglomeration effects are strongest when government constraints do not exceed the threshold. However, in developing countries, when this threshold is surpassed, the momentum for green transformation becomes insufficient. Finally, digital infrastructure positively promotes the green transformation of manufacturing agglomerations, although its effects are influenced by other factors.展开更多
Studying the spatiotemporal variation and driving mechanisms of vegetation net primary productivity(NPP)in the Guanzhong Plain Urban Agglomeration(GPUA)of China is highly important for regional green and low-carbon de...Studying the spatiotemporal variation and driving mechanisms of vegetation net primary productivity(NPP)in the Guanzhong Plain Urban Agglomeration(GPUA)of China is highly important for regional green and low-carbon development.This study used the Theil-Sen trend analysis,Mann-Kendall trend test,coefficient of variation,Hurst index,and machine learning method(eXtreme Gradient Boosting and SHapley Additive exPlanations(XGBoost-SHAP))to analyze the spatiotemporal variation of NPP in the GPUA from 2001 to 2020 and reveal its response to climate change and human activities.The results found that during 2001-2020,the averageNPP in the GPUA showed a significant upward trend,with an annual growth rate of 10.84 g C/(m^(2)•a).The multi-year average NPP in the GPUA was 484.83 g C/(m^(2)•a),with higher values in the southwestern Qinling Mountains and lower values in the central and northeastern cropland and built-up areas.The average coefficient of variation of NPP in the GPUA was 0.14,indicating a relatively stable state overall,but 72.72%of the study area showed weak anti-persistence,suggesting that NPP in most areas may have declined in the short term.According to XGBoost-SHAP analyses,elevation,land use type and precipitation were identified as the main driving factors of NPP.Appropriate precipitation and higher temperatures promote NPP growth,whereas extreme climates,high population density,and nighttime lighting inhibit NPP.This study has important theoretical and practical significance for achieving regional sustainable development,offers a scientific basis for formulating effective ecological protection and restoration strategies,and promotes green,coordinated,and sustainable development in the GPUA.展开更多
The superconducting high gradient magnetic separation(S-HGMS)technology can be used to effectively extract silica from iron ore tailings(IOTs).However,particle agglomeration in strong magnetic fields poses a challenge...The superconducting high gradient magnetic separation(S-HGMS)technology can be used to effectively extract silica from iron ore tailings(IOTs).However,particle agglomeration in strong magnetic fields poses a challenge in achieving optimal performance.In this study,we investigated the agglomeration of IOT particles and the mechanisms for its inhibition through surface analysis,density functional theory(DFT),and extended Derjaguin-Landau-Verwey-Overbeek(EDLVO)theory.Hematite was found to exhibit the highest magnetic moment among the minerals present in IOTs,making it particularly prone to magnetic agglomeration.The addition of the dispersant SDSH into the slurry was essential in promoting the dispersion of IOT particles during the S-HGMS process.This dispersant hydrolyzed to form HPO_(4)^(2-)and RSO_(3)^(-)groups in the solution,which then chemically adsorbed onto the metal ions exposed on the surfaces of non-quartz particles,increasing interparticle electrostatic repulsion.Furthermore,the RSO_(3)^(-)groups physically adsorbed onto the surface of quartz particles,resulting in strong steric repulsion and enhancing the hydrophilicity of the particle surfaces,thereby inhibiting magnetic agglomeration between the particles.Under optimal conditions,the SiO_(2)grade of the obtained high-grade silica powder increased from an initial value of 76.32%in IOTs to 97.42%,achieving a SiO_(2)recovery rate of 54.81%,which meets the requirements for quartz sand used in glass preparation.This study provides valuable insights into the magnetic agglomeration of IOT particles and its inhibition while providing a foundation for regulating S-HGMS processes.展开更多
Understanding the evolutionary trends and driving factors behind extreme hourly precipitation(EHP)in typical urban agglomerations is crucial for predicting and preventing rapid floods.We collected hourly precipitation...Understanding the evolutionary trends and driving factors behind extreme hourly precipitation(EHP)in typical urban agglomerations is crucial for predicting and preventing rapid floods.We collected hourly precipitation datasets from 31 observation stations in the Central Yunnan Urban Agglomeration(CYA)spanning from 2004 to 2020.Urban and rural observations were dynamically classified based on impervious surface fraction.Linear(Granger)and nonlinear causal methods(convergent cross-mapping and Liang–Kleeman information flow)were used to identify the causal impact mechanisms of large-scale circulation,environment and urbanization on EHP.Moreover,geo-detector further reveals the spatial influence of these factors and their interactions on EHP.Our findings revealed that EHP mainly occurred in the afternoon and at midnight.Also,the frequency and intensity of EHP in the CYA significantly(p≤0.05)increased from 2004 to 2020,especially in urban areas.The increasing rate in urban areas was higher than that in rural areas.However,the duration of EHP/hourly total precipitation exhibited a significant/nonsignificant decreasing trend with no significant difference between urban and rural areas.Causality tests and geo-detector indicated that EHP was impacted by natural variability and urbanization.Large-scale circulation indices such as the Pacific Decadal Oscillation,El Ni?o-Southern Oscillation,and Indian Ocean Dipole nonlinearly influenced EHP.Additionally,urban landscape layout,vegetation,and population variation may strengthen EHP by changing environmental factors such as temperature and relative humidity.Interactions exist between these factors and influence EHP,although large-scale circulation remains the dominant influence.With global climate warming and rapid urbanization in the CYA,the frequency and intensity of EHP may further amplify in the future.展开更多
Current mix design practices typically assume total blending and use the white curve of reclaimed asphalt pavement(RAP)to determine the gradation and optimum asphalt content(OAC)of recycled hot mix asphalt(HMA),often ...Current mix design practices typically assume total blending and use the white curve of reclaimed asphalt pavement(RAP)to determine the gradation and optimum asphalt content(OAC)of recycled hot mix asphalt(HMA),often overlooking the effects of RAP agglomeration and partial blending.This oversight can result in unsatisfactory performance,particularly when higher RAP content is used.Therefore,this paper reviews and discusses strategies for adjusting the mix design of recycled HMA to enhance its in-service performance.The discussion begins with RAP particle agglomeration,a significant phenomenon that significantly impacts the aggregate gradation of recycled HMA.Subsequently,detection methods to clarify the blending between virgin and RAP binders are described.Partial blending between RAP and virgin binders is common,and various indexes have been proposed to quantify the blending degree.Finally,the adjusted mix design method of recycled HMA is presented,emphasizing gradation optimization and corrected OAC.Gradation optimization should account for RAP agglomeration,while the corrected OAC should consider particle blending.Recycled HMA using the adjusted mix design exhibits improved crack resistance and fatigue life without substantially impairing rutting performance.This review aims to help both academics and highway agencies maximize the utilization of RAP materials within sustainable pavement frameworks.展开更多
China is one of the countries with the longest history in the world.The protection and development of historical and cultural resources is an issue worthy of attention in the fields of economic geography and urban-rur...China is one of the countries with the longest history in the world.The protection and development of historical and cultural resources is an issue worthy of attention in the fields of economic geography and urban-rural planning at the present stage.This study takes the Zhongyuan Urban Agglomeration,which is rich in historical and cultural heritage,as a specific case,analyzes the characteristics of the spatial-temporal distribution pattern of its historical and cultural resources.The results show that the distribution structure of historical and cultural element resources within the Zhongyuan Urban Agglomeration presents significant regional agglomeration and combination characteristics.In response to the analysis results,the study formulates an optimization strategy for the regional development pattern supported by the protection and development of historical and cultural resources,and initially proposes a matching spatial development pattern plan and policy recommendations for coordinated development.展开更多
Low-carbon urban development in China can pave the way to achieve the dualcarbon goal.Exploring how land use changes(LUCs)impact carbon storage(CS)under multi-climate scenarios in different urban agglomerations helps ...Low-carbon urban development in China can pave the way to achieve the dualcarbon goal.Exploring how land use changes(LUCs)impact carbon storage(CS)under multi-climate scenarios in different urban agglomerations helps to formulate differential scientific carbon mitigation policies.In this regard,this study constructs an integrated model of SD-PLUS-InVEST to simulate LUCs and CS changes under multi-climate change-based scenarios(SSP126,SSP245,SSP585)for three major urban agglomerations(3UAs)in the Yangtze River Economic Belt.Results demonstrate that land use demand in the 3UAs changes considerably in each scenario.Construction land in the 3UAs remains the most important growth category for the coming decade,but its increase varies in different scenarios.CS in the Yangtze River Delta Urban Agglomeration(YRDUA)and Mid-Yangtze River Urban Agglomeration(MYRUA)shows a similar downward trend under different scenarios,with scenario SSP245 decreasing the most,to 184,713.526 Tg and 384,459.729 Tg,respectively.CS in the Cheng-Yu(Chengdu-Chongqing)Urban Agglomeration(CYUA)exhibits the opposite upward trend,with scenario SSP126 increasing the most to 153,007.973 Tg.The major cause of CS loss remains the conversion of forest land to construction land in the YRDUA and MYRUA under different scenarios.However,in the CYUA,the conversion of forest land to cultivated land is the major driver of CS loss under scenario SSP126.In contrast,the conversion of cultivated land to construction land dominantly drives CS loss under scenarios SSP245 and SSP585.The conversion of water body to other land use types is the major cause of CS gain in the YRDUA and MYRUA under different scenarios.At the same time,in the CYUA,the driver is the conversion of cultivated land to forest land.These findings demonstrate the significance of the low-carbon development in urban agglomerations at different development stages at home and abroad.展开更多
Wetlands offer important ecological functions and values.Wetland functional zoning provides a reference and basis for sustainable fulfilment and management.In this study,two coastal urban agglomerations in South China...Wetlands offer important ecological functions and values.Wetland functional zoning provides a reference and basis for sustainable fulfilment and management.In this study,two coastal urban agglomerations in South China were taken as study areas,namely,the Guangxi Beibu Gulf(GBG)and Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Based on multisource information data,a wetland functional zoning system was constructed with the four levels of zoning concept,zoning principle,zoning basis,and zoning scheme.The functional zoning and dynamic analysis of wetlands from 1990 to 2020 were carried out from multiple perspectives of wetland ecological functions,wetland management and conservation functions.The results showed that:1)in terms of wetland ecological functions,the two coastal urban agglomerations were dominated by hydrological regulation and purification of environmental functional areas.The coastal region was largely characterized by the main functional areas of climate regulation and biodiversity maintenance.2)Regarding wetland management and conservation functions,two coastal urban agglomerations exhibited similar trends in terms of the sizes of their conservation and buffer zones from 1990 to 2020.Prevention and control zones were mainly located in core cities in a concentrated manner.Conservation zones largely comprised mountainous woodlands and important wetlands.3)The two coastal urban agglomerations could be divided into 21 wetland functional zones.The central river area has remained the main prevention and control zone for many years.Regarding conservation zones,ecological protection and restoration should be the main focus.Regarding buffer zones,the construction of wetlands and surrounding complex systems should be strengthened or enhanced.Regarding prevention and control zones,activities that do not affect wetland functions should be allowed,provided that they comply with existing laws and regulations.This study could provide technical support and practical application guidance for wetland regulation and management.展开更多
The inter-city linkage heat data provided by Baidu 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 Baidu 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
基金Under the auspices of Yunnan Provincial Science and Technology Project at Southwest United Graduate School(No.202302AO370012)National Natural Science Foundation of China(No.42201290)+1 种基金Talent Introduction Fund of Yunnan University(No.CZ22623101)the Fourteenth Program of Research Innovation Fund for Graduate Students of Yunnan University(No.KC-22221099)。
文摘Farmland transfer is an important land policy for reducing agricultural fragmentation and improving land use efficiency.Many studies have investigated the driving forces of farmland transfer at the farmers’scale.However,the overall spatial distribution and driving mechanisms of farmland transfer at the county scale has been less quantified.In this study,we evaluated farmland transfer and its spatial pattern in Central Yunnan Urban Agglomeration(CYUA)of China by using statistical data at the county scale in 2020.A so-cial-ecological indicator system,comprising natural endowment,social indicators,economic indicators,and landscape patterns,was es-tablished to explore the relationship between farmland transfer and its driving factors.Additionally,a heuristic structural equation mod-el(SEM)was employed to disentangle direct and indirect drivers of farmland transfer.The results indicated that significant spatial clusters of farmland transfer,with high transfer rates concentrated in highly urbanized areas and low transfer rates prevalent in tradition-al ethnic minority regions.Farmland transfer is primarily driven by soil quality,landscape patterns,terrain,and social-economic rurality.Specifically,higher soil quality and improved landscape connectivity facilitate farmland transfer directly,while gentler slopes promote farmland transfer indirectly by supporting better educational opportunities and fewer minority population.Improving rural vocational training and optimizing landscape patterns through land consolidation and redistribution are important in the mountainous areas.This study can provide valuable analytical framework for farmland management for other mountainous regions.
文摘Patna is among the cities high populated at risk of ecological and environmental deterioration due to a variety of human activities,such as poor land cover management.One of the most crucial elements of a successful land resource management plan is the evaluation of Land Use Land Cover(LULC).Over the past 20 years,our planet’s land cover resources have undergone substantial changes due to rapid development.The Land Use Land Cover(LULC)categories of the Patna Urban Agglomeration(PUA),including water bodies,agricultural land,barren land,built-up areas,and vegetation,were identified using Geographic Information System(GIS)techniques.Three multi-temporal images were analyzed and classified through supervised classification using the maximum likelihood method.By comparing three separately created LULC categorized maps from 1990 and 2024,temporal changes were analyzed.In order to update land cover or manage natural resources,it is vital to use change detection as a tool to identify changes in LULC over time in PUA,Patna between 1990,2010 and 2024.According to their respective Kappa coefficients,the accuracy rates for 1990,2010 and 2024 LULC are 91.66 and 94.93,respectively.An accuracy evaluation was conducted to determine the correctness of the classification system and to determine the efficacy of the LULC classification maps.One hundred reference test pixels were identified.There have been found significant changes in the LULC were built up area has increased doubled in last thirty-four years of timeline.
基金supported by the Humanities and Social Sciences Project of the Ministry of Education of the Peoples Republic(No.21YJCZH099)the National Natural Science Foundation of China(Nos.41401089 and 41741014)the Science and Technology Project of Sichuan Province(No.2023NSFSC1979).
文摘Majority of carbon emissions originate from fossil energy consumption,thus necessitating calculation and monitoring of carbon emissions from energy consumption.In this study,we utilized energy consumption data from Sichuan Province and Chongqing Municipality for the years 2000 to 2019 to estimate their statistical carbon emissions.We then employed nighttime light data to downscale and infer the spatial distribution of carbon emissions at the county level within the Chengdu-Chongqing urban agglomeration.Furthermore,we analyzed the spatial pattern of carbon emissions at the county level using the coefficient of variation and spatial autocorrelation,and we used the Geographically and Temporally Weighted Regression(GTWR)model to analyze the influencing factors of carbon emissions at this scale.The results of this study are as follows:(1)from 2000 to 2019,the overall carbon emissions in the Chengdu-Chongqing urban agglomeration showed an increasing trend followed by a decrease,with an average annual growth rate of 4.24%.However,in recent years,it has stabilized,and 2012 was the peak year for carbon emissions in the Chengdu-Chongqing urban agglomeration;(2)carbon emissions exhibited significant spatial clustering,with high-high clustering observed in the core urban areas of Chengdu and Chongqing and low-low clustering in the southern counties of the Chengdu-Chongqing urban agglomeration;(3)factors such as GDP,population(Pop),urbanization rate(Ur),and industrialization structure(Ic)all showed a significant influence on carbon emissions;(4)the spatial heterogeneity of each influencing factor was evident.
基金Under the auspices of the National Natural Science Foundation of China(No.52268008)。
文摘This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking and neutrality goals.This research ana-lyzes the spatial characteristics of carbon metabolism from 2000 to 2020 and uses models to identify stable carbon sink areas,positive carbon flow corridors,and carbon sequestration nodes.The goal is to construct a carbon metabolism spatial security pattern(CMSSP)and propose territorial ecological restoration strategies under different development demand scenarios.The results show the following:1)in 2020,the study area’s carbon sink decreased by 8.29×10^(4) t C/yr compared with that in 2010 and by 10.83×10^(4) t C/yr compared with that in 2000.High-carbon sinks were found mainly in mountainous areas,whereas low-carbon sinks are concentrated in urban con-struction land,rural residential areas,and land margins.2)From 2000 to 2020,the spatial security pattern of carbon metabolism tended to be‘high in the middle of the east and west and low in the gulf.’In 2000,2010,and 2020,16 stable carbon sinks were identified.The carbon energy flow density in Guangxi was greater than that in Guangdong and Hainan,with positive carbon flow corridors located primarily in Guangxi and Guangdong.The number of carbon sequestration nodes remained stable at approximately 15,mainly in Guangxi and Hainan.3)Scenario simulations revealed that under the Nature-based mild restoration scenario,the carbon sink rate will reach 611.85×10^(4) t C/yr by 2030 and increase to 612.45×10^(4) t C/yr by 2060,with stable carbon sinks increasing to 18.In the restora-tion scenario based on Anti-globalization,the carbon sink will decrease from 610.24×10^(4) t C/yr in 2030 to 605.19×10^(4) t C/yr in 2060,with the disappearance of some positive carbon flow corridors and stable carbon sinks.Under the Human-based sustainable restoration scenario,the carbon sink area will decrease from 607.00×10^(4) t C/yr in 2030 to 596.39×10^(4) t C/yr in 2060,with carbon sink areas frag-menting and positive carbon flow corridors becoming less dense.4)On the basis of the current and predicted CMSSPs,this study ex-plores spatial ecological restoration strategies for high-carbon storage areas in bay urban agglomerations at four levels:the land control region,urban agglomeration structure system,carbon sink structure and bay structure control region.
基金supported by the National Natural Science Foundation of China(Nos.U2241250 and U2441284)。
文摘AP(Ammonium Perchlorate)and HMX(Octogen)are the two oxidizers most often used in Nitrate-Ester-Plasticized Polyether(NEPE)rocket propellants.How the AP–HMX ratio influences the agglomeration of NEPE propellants remains unclear.We experimentally investigated the effect of the AP–HMX ratio on the combustion and agglomeration of NEPE propellants using burning rate test,quenched surface analysis,microscopic observations,and the collection of condensed combustion products.It was found that with the decrease in AP content from 40wt%to 10wt%,the burning rate decreased from 14.2 mm/s to 9.2 mm/s because the adiabatic flame temperature of NEPE propellants decreased from 3828 K to 3736 K.Pockets bounded by AP particles appeared on the surface when AP content was 40wt%;however,the accumulations grew and covered the burning surface eventually as the AP–HMX ratio decreased.The time required for the accumulation to coalesce into agglomerates increased with decreasing AP content.Even with similar agglomerate sizes,the coalescence time increased by 83%when the AP content decreased from 40wt%to 30wt%.The agglomerate size in the Condensed Combustion Products(CCPs)increased from 100μm to 200μm,and the fraction of large agglomerations increased from 6.4%to 24.7%when the AP content decreased from 40wt%to 10wt%.Overall,the high flame temperature of the AP particles enhanced the decomposition of the surrounding binder,resulting in the rapid ejection of the aluminum particles into the gas,which had a separating effect on the accumulation,thus weakening the agglomeration.
基金National Natural Science Foundation of China(Nos.U21A20116,U21A20117 and 52304347)National Natural Science Foundation of Liaoning(Nos.2023-MSBA-135 and 2023-BSBA-107)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.N2409006 and N2409008)are acknowledged to support this workSwedish Foundation for International Cooperation in Research and Higher Education(STINT,Project No.IB2022-9228)is acknowledged by W.Mu to support his visit between KTH(Sweden)and NEU(China).
文摘Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of different Ti and Al contents on the agglomeration behavior of non-metallic inclusions in low carbon steels.Furthermore,the agglomeration mechanism of inclusions was investigated through quantitative analysis of in-situ observation experiments and a modified Kralchevsky-Paunov model.The obtained results indicate that Al_(2)O_(3)is the main type inclusion in the low-alloys steels with both Al and Ti addition.This type of inclusion is more likely to absorb surrounding small-size inclusion particles,leading to a further growth for the cluster formation and contributing to a serious engineering problem,nozzle clogging.Besides,TiO_(x)is the main type inclusion in the molten steel with only Ti addition,and this type of inclusion is less likely to agglomerate and the individual inclusion particles show a‘free’motion with the fluid of molten steel.The difference between these two types of inclusions is due to the difference in attractive force and action distance at the meniscus created by the inclusion/steel/Ar multiple interfaces and influenced by the physical parameters,e.g.,contact angle and interface energy between inclusion and steel,and surface tension of the melt.
基金support of Postdoctoral Fellowship Program of CPSF(GZC20230393)Natural Science Foundation of Liaoning Province in China(2023-BSBA-112)Fundamental Research Funds for the Central Universities(N2425032).
文摘The formation of large-sized inclusions cluster severely impacts the continuous casting process and product quality of titanium-containing steel.Thermodynamic calculations were initially conducted to predict the formation of various complex oxide inclusions,namely Al_(2)O_(3),TiO_(x)and Al-Ti-O.Based on that,laboratory-scale experiments were designed to prepare samples with a single type of inclusions.Then,the scanning electron microscope-energy dispersive spectrometer was used for quantitative characterization.Subsequently,the agglomeration behavior of inclusions in Fe-Al-Ti-O melt was observed in situ by high-temperature confocal laser scanning microscopy.Furthermore,a quantitative analysis of the agglomeration characteristics of the various inclusions was conducted based on the attractive forces in accordance with Newton's second law and the capillary forces as described by the Kralchevsky-Paunov model.The results indicate that the size of Al_(2)O_(3)inclusions is larger than that of TiO_(x)and Al-Ti-O,but the number density of TiO_(x)is the highest.Based on the in situ observation and the theoretical calculation,Al_(2)O_(3),TiO_(x)and Al-Ti-O inclusions can all agglomerate into large-sized clusters without segregation,but the agglomeration tendency of Al_(2)O_(3)and TiO_(x)is stronger than that of Al-Ti-O.The attractive force between Al_(2)O_(3)inclusions’pair is the largest,ranging from 2.26×10^(-15)to 6.12×10^(-14)N,followed by TiO_(x)(7.13×10^(-16)to 3.56×10^(-14)N)and Al-Ti-O(1.16×10^(-17)to 3.77×10^(-16)N).
基金sponsored by the National Social Science Fund of China[Grant No.23VMG006].
文摘This study determines whether industrial agglomeration can solve energy poverty(ENPO)by applying a provincial dataset(2002-2019)to assess the potential effect of industrial agglomeration on ENPO.Additionally,this study conducts an in-depth exploration of provincial heterogeneity and its influence mechanisms.The conclusions are as follows:①Industrial agglomeration is negatively correlated with ENPO;by implication,enhancing industrial agglomeration is a driving force for reducing ENPO.②The alleviating effect of industrial agglomeration on ENPO in the midwestern region is considerably higher than that in the eastern region,and the ENPO alleviation effect of the high agglomeration region is better than that in the low agglomeration region.③Foreign investment and energy efficiency have a mediating role,that is,they are valid transmission pathways for industrial agglomeration to solve the ENPO issue.Relevant policy suggestions for reducing ENPO by accelerating industrial agglomeration are proposed by drawing on the above three conclusions.
基金National Natural Science Foundation of China,No.42171216,No.71733001Key R&D Program of Beijing Municipal Education Commission,No.KZ202210038047Tsinghua University Initiative Scientific Research Program,No.2022THZWJC15。
文摘Research on urban health constitutes an important issue in the field of health geography and also a strong propeller of the Healthy China Initiative.As the main form that realizes new-type urbanization,urban agglomerations should become the primal sites for the construction of a“Healthy China”.The evaluation of healthy cities’development in urban agglomerations has both theoretical and practical values.Based on the concept of urban health and its evaluation models,this paper developed an evaluation framework for healthy cities that involved multiple data sources.With 19 urban agglomerations in China as the research subjects,we used CRITIC weighting and geographical detectors to examine the geographies of healthy cities and their influencing factors in 2010 and 2020.The results were fourfold.Firstly,the urban health level of China significantly increased from 2010 to 2020,and the comprehensive health index developed towards a positive skewed distribution,along with a shift from“low in the hinterland-high in the coastal areas”to a“multipolar”pattern led by the coastal and southwest urban agglomerations.Secondly,among various dimensions of urban health,the healthy environment index became improved with narrowed regional differences;while the health services index was still polarized;health collaboration was upgraded with a strengthened intercity health network;the healthy population index slightly declined and converged to the middle.Thirdly,urban health in China has initially demonstrated the characteristics of a H-H pattern in the Yangtze River Delta and ChengduChongqing regions,as well as L-L clusters in the northern urban agglomerations,the narrowed regional differences,and increasing coordination within each urban agglomeration.Fourthly,the geographical detector found that economy,urbanization and the human capital were significant external factors that affected urban health development.The explanatory power of technological innovation and opening to the outside world were also increasing.The development of healthy cities is yet to be transformed into regional health integration.
基金National Natural Science Foundation of China,No.42330106。
文摘Dryland regions face complex interactions between urbanization and ecological changes,where effective coordination is essential for enhancing sustainability and resilience.However,most studies concentrate on the national or provincial scales,with insufficient research on county-level coordination,limiting the ability to provide targeted polifrom a precise perspective.This study addresses this gap by analyzing 39 counties within the Hohhot-Baotou-Ordos-Yulin Urban Agglomeration(HBOYUA),a typical dryland urban cluster in China.We use daytime and nighttime remote sensing images to track the spatio-temporal evolution of urbanization and ecological conditions from 1992 to 2023.A novel quantitative framework based on an improved coupling coordination degree(CCD)is proposed to assess their coordination relationship.The results reveal that:(1)Urbanization and ecological quality both exhibited fluctuating upward trends,with spatial heterogeneity increasing for urbanization and decreasing for the eco-environment.Regions with better ecological conditions had higher urbanization levels.(2)The overall coordinated level improved from imbalance(0.36)to low-level coordination(0.55),although its spatial distribution remained uneven,with central urban areas showing higher CCD than surrounding counties.(3)Socioeconomic factors exerted greater effects on CCD than natural factors,with GDP and land surface temperature(LST)playing a significant role in interaction analysis.(4)In western arid regions,urbanization did not necessarily harm ecosystems;instead,ecological conditions improved alongside urbanization.This research offers targeted and valuable references for county and city governments in resource allocation and sustainable development.The proposed methodology is also adaptable for urban resilience studies in other regions.
基金supported by the National Key Research and Development Program of China(No.2019YFD1100203).
文摘Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks.In this study,tapwater(TW)and bottledwater(BW)sampleswere collected from eight cities in the Yangtze River Delta urban agglomeration in China,and their OAP levelswere analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction(Hi-throat/Hi-volume SPE techniques).This study is the first to systematically characterize the trace levels of OAPs in drinking water in China.Our findings indicated that the total concentration of OAPs(OAPs)in TW(average 11.06±4.99 ng/L)was 29.4%higher than in BW(average 8.55±3.98 ng/L)and fewer kinds(7)of OAPs were detected in BW.Furthermore,the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range,particularly in males,with molinate being the major contributor(61.3%)to OAP exposure.Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants(DWTPs).Furthermore,our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water(up to 87.5%).Therefore,our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.
基金supported by the National Social Science Founda‐tion of China[Grant No.20&ZD100]the Shandong Province Key Research and Development Program(Soft Science)Major Project[Grant No.2024RZA0101].
文摘In the context of China’ s dual carbon goals, transforming traditional manufacturing agglomeration into green manufacturing agglomeration is pivotal in aligning economic development with environmental protection, ultimately contributing to the country’ s high-quality economic growth. This study examines the dynamic nonlinear effects of manufacturing agglomeration on economic development, energy consumption, environmental pollution, and green total factor productivity. We developed a theoretical framework that considered local government constraints and incentives as transition variables and employed panel data from 280 cities at or above the prefecture level in China from 2006 to 2020 using a Panel Smooth Transition Regression model. The results reveal that, first, under both constraints and incentives, a single threshold effect exists beyond which the positive impact of manufacturing agglomeration on economic development, energy consumption, and environmental pollution gradually weakens. Second, the spatiotemporal evolution of manufacturing agglomeration shows that traditional manufacturing agglomerations are gradually spreading from the central and western regions to the resourcebased regions in the eastern part of the country, while green manufacturing agglomerations are shrinking annually. Third, a comparative analysis indicates that, in both developed and developing countries, manufacturing agglomeration effects are strongest when government constraints do not exceed the threshold. However, in developing countries, when this threshold is surpassed, the momentum for green transformation becomes insufficient. Finally, digital infrastructure positively promotes the green transformation of manufacturing agglomerations, although its effects are influenced by other factors.
基金funded by the Xi'an Social Science Fund(24QL38).
文摘Studying the spatiotemporal variation and driving mechanisms of vegetation net primary productivity(NPP)in the Guanzhong Plain Urban Agglomeration(GPUA)of China is highly important for regional green and low-carbon development.This study used the Theil-Sen trend analysis,Mann-Kendall trend test,coefficient of variation,Hurst index,and machine learning method(eXtreme Gradient Boosting and SHapley Additive exPlanations(XGBoost-SHAP))to analyze the spatiotemporal variation of NPP in the GPUA from 2001 to 2020 and reveal its response to climate change and human activities.The results found that during 2001-2020,the averageNPP in the GPUA showed a significant upward trend,with an annual growth rate of 10.84 g C/(m^(2)•a).The multi-year average NPP in the GPUA was 484.83 g C/(m^(2)•a),with higher values in the southwestern Qinling Mountains and lower values in the central and northeastern cropland and built-up areas.The average coefficient of variation of NPP in the GPUA was 0.14,indicating a relatively stable state overall,but 72.72%of the study area showed weak anti-persistence,suggesting that NPP in most areas may have declined in the short term.According to XGBoost-SHAP analyses,elevation,land use type and precipitation were identified as the main driving factors of NPP.Appropriate precipitation and higher temperatures promote NPP growth,whereas extreme climates,high population density,and nighttime lighting inhibit NPP.This study has important theoretical and practical significance for achieving regional sustainable development,offers a scientific basis for formulating effective ecological protection and restoration strategies,and promotes green,coordinated,and sustainable development in the GPUA.
基金supported by USTB Institute for International People-to-People Exchange in Mining,Metallurgy and Metals Industries(No.FRF-IPPE-2404)Scientific Research Platform Construction Fund for the Introduction of High-Level Talents at Kunming University of Science and Technology(No.CA25073M246A).
文摘The superconducting high gradient magnetic separation(S-HGMS)technology can be used to effectively extract silica from iron ore tailings(IOTs).However,particle agglomeration in strong magnetic fields poses a challenge in achieving optimal performance.In this study,we investigated the agglomeration of IOT particles and the mechanisms for its inhibition through surface analysis,density functional theory(DFT),and extended Derjaguin-Landau-Verwey-Overbeek(EDLVO)theory.Hematite was found to exhibit the highest magnetic moment among the minerals present in IOTs,making it particularly prone to magnetic agglomeration.The addition of the dispersant SDSH into the slurry was essential in promoting the dispersion of IOT particles during the S-HGMS process.This dispersant hydrolyzed to form HPO_(4)^(2-)and RSO_(3)^(-)groups in the solution,which then chemically adsorbed onto the metal ions exposed on the surfaces of non-quartz particles,increasing interparticle electrostatic repulsion.Furthermore,the RSO_(3)^(-)groups physically adsorbed onto the surface of quartz particles,resulting in strong steric repulsion and enhancing the hydrophilicity of the particle surfaces,thereby inhibiting magnetic agglomeration between the particles.Under optimal conditions,the SiO_(2)grade of the obtained high-grade silica powder increased from an initial value of 76.32%in IOTs to 97.42%,achieving a SiO_(2)recovery rate of 54.81%,which meets the requirements for quartz sand used in glass preparation.This study provides valuable insights into the magnetic agglomeration of IOT particles and its inhibition while providing a foundation for regulating S-HGMS processes.
基金National Natural Science Foundation of China,No.42461012Yunnan Fundamental Research Projects,No.202201AU070064。
文摘Understanding the evolutionary trends and driving factors behind extreme hourly precipitation(EHP)in typical urban agglomerations is crucial for predicting and preventing rapid floods.We collected hourly precipitation datasets from 31 observation stations in the Central Yunnan Urban Agglomeration(CYA)spanning from 2004 to 2020.Urban and rural observations were dynamically classified based on impervious surface fraction.Linear(Granger)and nonlinear causal methods(convergent cross-mapping and Liang–Kleeman information flow)were used to identify the causal impact mechanisms of large-scale circulation,environment and urbanization on EHP.Moreover,geo-detector further reveals the spatial influence of these factors and their interactions on EHP.Our findings revealed that EHP mainly occurred in the afternoon and at midnight.Also,the frequency and intensity of EHP in the CYA significantly(p≤0.05)increased from 2004 to 2020,especially in urban areas.The increasing rate in urban areas was higher than that in rural areas.However,the duration of EHP/hourly total precipitation exhibited a significant/nonsignificant decreasing trend with no significant difference between urban and rural areas.Causality tests and geo-detector indicated that EHP was impacted by natural variability and urbanization.Large-scale circulation indices such as the Pacific Decadal Oscillation,El Ni?o-Southern Oscillation,and Indian Ocean Dipole nonlinearly influenced EHP.Additionally,urban landscape layout,vegetation,and population variation may strengthen EHP by changing environmental factors such as temperature and relative humidity.Interactions exist between these factors and influence EHP,although large-scale circulation remains the dominant influence.With global climate warming and rapid urbanization in the CYA,the frequency and intensity of EHP may further amplify in the future.
基金sponsored by the National Natural Science Foundation of China(52178420,52408476)Special subsidy from Heilongjiang Provincial People's Government(HITTY-20190028)+1 种基金Postdoctoral Fellowship Program of CPSF(GZC20242207)the Fundamental Research Funds for the Central Universities(HIT.DZJJ.2023086).
文摘Current mix design practices typically assume total blending and use the white curve of reclaimed asphalt pavement(RAP)to determine the gradation and optimum asphalt content(OAC)of recycled hot mix asphalt(HMA),often overlooking the effects of RAP agglomeration and partial blending.This oversight can result in unsatisfactory performance,particularly when higher RAP content is used.Therefore,this paper reviews and discusses strategies for adjusting the mix design of recycled HMA to enhance its in-service performance.The discussion begins with RAP particle agglomeration,a significant phenomenon that significantly impacts the aggregate gradation of recycled HMA.Subsequently,detection methods to clarify the blending between virgin and RAP binders are described.Partial blending between RAP and virgin binders is common,and various indexes have been proposed to quantify the blending degree.Finally,the adjusted mix design method of recycled HMA is presented,emphasizing gradation optimization and corrected OAC.Gradation optimization should account for RAP agglomeration,while the corrected OAC should consider particle blending.Recycled HMA using the adjusted mix design exhibits improved crack resistance and fatigue life without substantially impairing rutting performance.This review aims to help both academics and highway agencies maximize the utilization of RAP materials within sustainable pavement frameworks.
基金Major Program of National Fund of Philosophy and Social Science of China(24&ZD148).
文摘China is one of the countries with the longest history in the world.The protection and development of historical and cultural resources is an issue worthy of attention in the fields of economic geography and urban-rural planning at the present stage.This study takes the Zhongyuan Urban Agglomeration,which is rich in historical and cultural heritage,as a specific case,analyzes the characteristics of the spatial-temporal distribution pattern of its historical and cultural resources.The results show that the distribution structure of historical and cultural element resources within the Zhongyuan Urban Agglomeration presents significant regional agglomeration and combination characteristics.In response to the analysis results,the study formulates an optimization strategy for the regional development pattern supported by the protection and development of historical and cultural resources,and initially proposes a matching spatial development pattern plan and policy recommendations for coordinated development.
基金Key Project of National Social Science Fund,No.23AZD032National Natural Science Foundation of China No.42371258Program of China Scholarship Council No.202306850036。
文摘Low-carbon urban development in China can pave the way to achieve the dualcarbon goal.Exploring how land use changes(LUCs)impact carbon storage(CS)under multi-climate scenarios in different urban agglomerations helps to formulate differential scientific carbon mitigation policies.In this regard,this study constructs an integrated model of SD-PLUS-InVEST to simulate LUCs and CS changes under multi-climate change-based scenarios(SSP126,SSP245,SSP585)for three major urban agglomerations(3UAs)in the Yangtze River Economic Belt.Results demonstrate that land use demand in the 3UAs changes considerably in each scenario.Construction land in the 3UAs remains the most important growth category for the coming decade,but its increase varies in different scenarios.CS in the Yangtze River Delta Urban Agglomeration(YRDUA)and Mid-Yangtze River Urban Agglomeration(MYRUA)shows a similar downward trend under different scenarios,with scenario SSP245 decreasing the most,to 184,713.526 Tg and 384,459.729 Tg,respectively.CS in the Cheng-Yu(Chengdu-Chongqing)Urban Agglomeration(CYUA)exhibits the opposite upward trend,with scenario SSP126 increasing the most to 153,007.973 Tg.The major cause of CS loss remains the conversion of forest land to construction land in the YRDUA and MYRUA under different scenarios.However,in the CYUA,the conversion of forest land to cultivated land is the major driver of CS loss under scenario SSP126.In contrast,the conversion of cultivated land to construction land dominantly drives CS loss under scenarios SSP245 and SSP585.The conversion of water body to other land use types is the major cause of CS gain in the YRDUA and MYRUA under different scenarios.At the same time,in the CYUA,the driver is the conversion of cultivated land to forest land.These findings demonstrate the significance of the low-carbon development in urban agglomerations at different development stages at home and abroad.
基金Under the auspices of National Natural Science Foundation of China(No.U21A2022,U1901219,42101369)National Key Research and Development Program of China(No.2023YFF0807204)。
文摘Wetlands offer important ecological functions and values.Wetland functional zoning provides a reference and basis for sustainable fulfilment and management.In this study,two coastal urban agglomerations in South China were taken as study areas,namely,the Guangxi Beibu Gulf(GBG)and Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Based on multisource information data,a wetland functional zoning system was constructed with the four levels of zoning concept,zoning principle,zoning basis,and zoning scheme.The functional zoning and dynamic analysis of wetlands from 1990 to 2020 were carried out from multiple perspectives of wetland ecological functions,wetland management and conservation functions.The results showed that:1)in terms of wetland ecological functions,the two coastal urban agglomerations were dominated by hydrological regulation and purification of environmental functional areas.The coastal region was largely characterized by the main functional areas of climate regulation and biodiversity maintenance.2)Regarding wetland management and conservation functions,two coastal urban agglomerations exhibited similar trends in terms of the sizes of their conservation and buffer zones from 1990 to 2020.Prevention and control zones were mainly located in core cities in a concentrated manner.Conservation zones largely comprised mountainous woodlands and important wetlands.3)The two coastal urban agglomerations could be divided into 21 wetland functional zones.The central river area has remained the main prevention and control zone for many years.Regarding conservation zones,ecological protection and restoration should be the main focus.Regarding buffer zones,the construction of wetlands and surrounding complex systems should be strengthened or enhanced.Regarding prevention and control zones,activities that do not affect wetland functions should be allowed,provided that they comply with existing laws and regulations.This study could provide technical support and practical application guidance for wetland regulation and management.
文摘The inter-city linkage heat data provided by Baidu 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.
