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
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
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
This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and...This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.展开更多
The article presents the results of experimental studies on the gasification of mixtures of brown coal and polyethylene(up to 20 wt%fraction)in a laboratory reactor.The work aims to study the agglomeration process dur...The article presents the results of experimental studies on the gasification of mixtures of brown coal and polyethylene(up to 20 wt%fraction)in a laboratory reactor.The work aims to study the agglomeration process during the heating and oxidation of the mixtures.The measurement results(gas composition,pressure drop)provide indirect information on the dynamics of thermal decomposition and structural changes in the fuel bed.We have shown that the interaction between polyethylene and a coal surface leads to the formation of dense agglomerates,in which the molten polymer acts as a binder.Clinkers form as a result of interfacial interactions between components and filtration flow rearranging.The hydrogen/carbon ratio in the solid residue of coal-polyethylene co-gasification increases from 0.07–0.2 to 1.11,indicating the formation of stable hydrocarbon compounds on the carbon surface.The conducted research makes it possible to identify possible interactions between chemical reactions and transfer processes that lead to agglomeration in mixtures of coal with polyethylene.展开更多
Asphalt extraction test and scanning electron microscopy(SEM) were used for analysis of agglomerations of reclaimed asphalt pavement(RAP) particles. In order to quantify the agglomeration degree of RAP, the fineness m...Asphalt extraction test and scanning electron microscopy(SEM) were used for analysis of agglomerations of reclaimed asphalt pavement(RAP) particles. In order to quantify the agglomeration degree of RAP, the fineness modulus ratio(FMR) and the percentage loss index(PLI) were proposed. In addition, grey correlation analysis was conducted to discuss the relationship between particle agglomerations and RAP size,asphalt content(AC), and surface area. Two indexes indicate that the agglomeration degree increases in general as the RAP size reduces. This can be attributed to that particles are prone to agglomeration in the case of higher AC. Based on the SEM images and the material composition of RAP, the particle agglomeration in RAP can be classified into weak agglomeration and strong agglomeration. Grey correlation analysis shows that AC is the crucial factor affecting the agglomeration degree and RAP variability. In order to produce consistent and stable reclaimed mixtures, disposal measures of RAP are suggested to lower the AC of RAP.展开更多
Dalian, Shenyang, Changchun and Harbin are the four core cities which play an essential role in terms of promoting the economic development in Northeast China. In this paper, the impact of urban agglomeration on labor...Dalian, Shenyang, Changchun and Harbin are the four core cities which play an essential role in terms of promoting the economic development in Northeast China. In this paper, the impact of urban agglomeration on labor productivity is explored by making comparisons among these four cities. The model used for analysis is a classical model derived from previous studies. Some indicators, such as population density and economic density, were selected to examine the impact of urban agglomeration on the labor productivity based on the time-series data for the four cities from 1990 to 2007. The four main conclusions are： l） The promotion from the growth rate of population density on the growth rate of labor productivity is limited. 2） The negative relationship exists between the growth rate of employment density and the growth rate of labor productivity. 3） Agglomeration effect exists in the four cities, the highest one is Dalian, Shenyang takes the second place, followed by Changchun and Harbin, and the predominant promotion exerted on the labor productivity is the output density.展开更多
The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobicmodified nan...The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobicmodified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly(octadecyl, docosyl acrylate) and poly(acrylate-α-olefin) onto the surface of nano-sized SiO_(2) were synthesized by grafting polymerization method.The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM) and thermogravimetric analysis(TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO_(2) nanoparticle(PDA@SiO_(2)) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20℃, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules,thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO_(2) hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.展开更多
The mechanical properties of graphene reinforced composites are often hampered by challenges related to the dispersion and aggregation of graphene within the matrix.This paper explores the mechanism of cooling rate,pr...The mechanical properties of graphene reinforced composites are often hampered by challenges related to the dispersion and aggregation of graphene within the matrix.This paper explores the mechanism of cooling rate,process temperature,and process pressure’s influence on the agglomeration behavior of graphene and the tensile response of composites from a computer simulation technology,namely molecular dynamics.Our findings reveal that the cooling rate exerts minimal influence on the tensile response of composites.Conversely,processing temperature significantly affects the degree of graphene aggregation,with higher temperatures leading to the formation of larger-sized graphene clusters.In contrast,processing pressure exhibits negligible impact on the degree of graphene aggregation,and increasing pressure effectively mitigates the formation of large-sized graphene clusters.Moreover,we elucidate the intrinsic factors governing the mechanical response to variations in processing parameters.Notably,we observe that the stretching process facilitates the decomposition of large-sized graphene clusters into smaller ones.This research contributes to the advancement of lightweight metal matrix composites by offering insights into optimizing processing parameters.Additionally,it provides crucial theoretical underpinnings for developing high-performance graphene-reinforced composites.展开更多
Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structure...Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.展开更多
It is of importance to enhance the urban areas'capacity for population aggregation in underdeveloped regions,aiming to rectify the imbalanced and insufficient pattern of economic development in China.Taking the Ta...It is of importance to enhance the urban areas'capacity for population aggregation in underdeveloped regions,aiming to rectify the imbalanced and insufficient pattern of economic development in China.Taking the Taiyuan Metropolitan Area(TMA)in central China as a case study,this paper examines the evolutionary process and characteristics of population agglomeration from 2000 to 2020,and identifies factors associated with agglomeration and their spatial effects.The findings indicated that:1)against the background of sustained population shrinkage in the provincial area,the TMA showed a demographic trend of steady increase,albeit with a decelerated growth rate.In the metropolitan area,urban population size continued to grow rapidly,whereas the rural areas endured sustained losses.Disparities in city size continued to widen,and the polarization of concentrated population in the core cities kept increasing.2)Agglomerations in both secondary and service industries had significant positive effects on local population agglomeration,with the former effect being stronger.Regional economic development,government fiscal expenditure,and financial advancement all contributed to facilitating local population clustering.From a spatial spillover perspective,service agglomeration and financial development promoted population agglomeration in surrounding areas.Conversely,fiscal expenditure inhibited such agglomeration.As for industrial agglomeration and regional economic development,their spatial spillover effects were non-significant.The results obtained reveal several policy implications aimed at enhancing the population agglomeration capacity of the metropolitan area in underdeveloped regions during the new era.展开更多
High-quality development is the primary task of comprehensively building a socialist,modern country,as well as the primary task of building urban agglomerations in China.Based on the five development concepts,this pap...High-quality development is the primary task of comprehensively building a socialist,modern country,as well as the primary task of building urban agglomerations in China.Based on the five development concepts,this paper used the entropy method to measure the High Quality Development Index(HQDI)of the five major urban agglomerations.The results showed that the HQDI of the five major urban agglomerations shows a fluctuating upward trend.First,using the Dagum Gini coefficient to explore the sources of HQDI development differences in urban agglomerations,we found that the main source of HQDI differences in urban agglomerations was inter-regional differences,while intra-regional differences were not important.Second,kernel density estimation was used to test the dynamic evolution trend of HQDI within urban agglomerations.There was a polarisation phenomenon in the HQDI of urban agglomerations,such as the Pearl River Delta urban agglomeration and the Chengdu-Chongqing urban agglomeration.But overall,the degree of imbalance had decreased.Third,using geographic detectors to examine the driving factors of HQDI in urban agglomerations,we found that the main driving forces for improving HQDI in urban agglomerations were economic growth,artificial intelligence technology and fiscal decentralisation.All the interaction factors had greater explanatory power for the spatial differentiation of HQDI,which can be divided into two types:two-factor improvement and non-linear improvement.This study is conducive to improving and enriching the theoretical system for evaluating the high quality development of urban agglomerations,and provides policy references for promoting the high quality development of urban agglomerations.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
Under the background of new infrastructure,the Yellow River Basin’s superior growth cannot be separated originating with the synergistic effect of scientific and technological inventiveness and ecological civilizatio...Under the background of new infrastructure,the Yellow River Basin’s superior growth cannot be separated originating with the synergistic effect of scientific and technological inventiveness and ecological civilization construction.In light of the coupling coordination analysis of the coordination effect of provincial high-tech industry agglomeration and resource carrying capacity in the Yellow River Basin from 2009 to 2021,The evolution of the geographical and temporal pattern of development was investigated using the Moran index and kernel density estimation.The results show that the agglomeration of high-tech industries in the Yellow River Basin presents a development trend of seek improvement in stability,and there is a good coupling and coordination throughout the progression of scientific and technological innovation and the loading capacity of the resource,from the viewpoint of a time series.From the perspective of spatial pattern distribution,the whole basin aims at the lower reaches,accelerates the optimization of digital industry and promotes Yellow River Basin development of superior quality through innovation support and increase of input,and based on policy guidance.展开更多
Urban agglomerations,serving as pivotal centers of human activity,undergo swift alterations in ecosystem services prompted by shifts in land utilization.Strengthening the monitoring of ecosystem services in present an...Urban agglomerations,serving as pivotal centers of human activity,undergo swift alterations in ecosystem services prompted by shifts in land utilization.Strengthening the monitoring of ecosystem services in present and future urban agglomerations contributes to the rational planning of these areas and enhances the well-being of their inhabitants.Here,we analyzed land use conversion in the Yangtze River Delta(YRD)urban agglomeration during 1990-2020 and discussed the spatiotemporal response and main drivers of changes in ecosystem service value(ESV).By considering the different development strategic directions described in land use planning policies,we predicted land use conversion and its impact on ESV using the Future Land Use Simulation(FLUS)model in three scenari-os in 2025 and 2030.Results show that:1)from 1990 to 2020,land use change is mainly manifested as the continuous expansion of con-struction land to cultivated land.Among the reduced cultivated land,82.2%were occupied by construction land.2)The land use types conversion caused a loss of 21.85 billion yuan(RMB)in ESV during 1990-2020.Moreover,the large reduction of cultivated land area led to the continuous decline of food production value,accounting for 13%of the total ESV loss.3)From 2020 to 2030,land use change will mainly focus on Yangzhou and Zhenjiang in central Jiangsu Province and Taizhou in southern Zhejiang Province.Under the BAU(natural development)and ED(cultivated land protection)scenarios,construction land expansion remains dominant.In contrast,under the EP(ecological protection)scenario,the areas of water bodies and forest land increase significantly.Among the different scenarios,ESV is highest in the EP scenario,making it the optimal solution for sustainable land use.It can be seen that the space use conflict among urban,agriculture and ecology is a key factor leading to ESV change in the urban agglomeration of Yangtze River Delta.There-fore,it is crucial to maintain spatial land use coordination.Our findings provide suggestions for scientific and rational land use planning for the urban agglomeration.展开更多
This paper falls into the broad area of economic geography and economics of creativity,and it presents an alternative approach to explain why total factor productivity(TFP)growth is different across China′s regions.I...This paper falls into the broad area of economic geography and economics of creativity,and it presents an alternative approach to explain why total factor productivity(TFP)growth is different across China′s regions.It establishes an empirical model to estimate the spatial agglomeration effects of creative industries on regional TFP growth,using China′s provincial panel data during the period of 2003 to 2010.We found that the creative industries agglomeration(CIA)has significant and positive impact on regional TFP growth.The result also implies that the CIA can facilitate regional TFP growth through promoting regional innovation instead of improving regional efficiency.Therefore,we argue that policy makers should take some measures to retain and establish more creative zones.展开更多
Spatial structure of rural tourism in the urban agglomerations of Wuhan was analyzed by comprehensively studying relevant documents about rural tourism,and reviewing previous researches on the concept and spatial stru...Spatial structure of rural tourism in the urban agglomerations of Wuhan was analyzed by comprehensively studying relevant documents about rural tourism,and reviewing previous researches on the concept and spatial structure of rural tourism.Through investigating rural tourist resources in the study area,resource advantages and characteristics of 9 cities were introduced,and the Gini Coefficient was taken to quantitatively analyze spatial patterns of its rural tourist villages,the obviously imbalanced concentration of these villages was pointed out.By measuring connectivity and accessibility of regional spaces in the study area,its traffic connectivity was proved moderate,and accessibility of each tourist village and town was fine.Then an optimized spatial structure was proposed for the rural tourism development in Wuhan Urban Agglomerations,that is,"one core,one belt and three districts".展开更多
[Objective] This paper aimed at studying the agglomeration and fluctuation situation of rice production in Hunan Province during the past 10 years.[Method] Data were collected from Hunan Rural Statistical Yearbook（20...[Objective] This paper aimed at studying the agglomeration and fluctuation situation of rice production in Hunan Province during the past 10 years.[Method] Data were collected from Hunan Rural Statistical Yearbook（2001-2010）.Taking the concentration index of sown area and production（CDI） and the volatility index（VI） as the main indicators,the agglomeration and fluctuation situation of paddy rice,early-season rice,middle-season rice and single-season late rice,late-season rice,good quality early-season rice,good quality middle-season rice and good quality single-season late rice,good quality late-season rice production in each major rice-producing area of Hunan Province during the past 10 years had been studied.[Result] The orders of concentration index of sown areas and production of paddy rice,early-season rice,middle-season rice and single-season late rice,late-season rice,good quality early-season rice,good quality middle-season rice and good quality single-season late rice,good quality late-season rice in Hunan Province varied,but the orders of volatility index were consistent.The stable areas,relatively stable areas and fluctuant areas in sown areas and production of different major rice-producing areas were defined.[Conclusion] The research had provided basis for optimizing the layout of rice production in Hunan Province,promoting agglomeration and development of rice production and translating the comparative advantages into the competitive advantages.展开更多
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support and encouragement of the Joint Funds of the National Natural Science Foundation of China(No.U21B2095)the Major Research Project of National Natural Science Foundation of China(No.91834303).
文摘This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.
文摘The article presents the results of experimental studies on the gasification of mixtures of brown coal and polyethylene(up to 20 wt%fraction)in a laboratory reactor.The work aims to study the agglomeration process during the heating and oxidation of the mixtures.The measurement results(gas composition,pressure drop)provide indirect information on the dynamics of thermal decomposition and structural changes in the fuel bed.We have shown that the interaction between polyethylene and a coal surface leads to the formation of dense agglomerates,in which the molten polymer acts as a binder.Clinkers form as a result of interfacial interactions between components and filtration flow rearranging.The hydrogen/carbon ratio in the solid residue of coal-polyethylene co-gasification increases from 0.07–0.2 to 1.11,indicating the formation of stable hydrocarbon compounds on the carbon surface.The conducted research makes it possible to identify possible interactions between chemical reactions and transfer processes that lead to agglomeration in mixtures of coal with polyethylene.
基金Funded by the Postgraduate Research and Practice Innovation Program of Jiangsu Province (No.KYCX21_0496)the Fundamental Research Funds for the Central Universities (for student)+1 种基金the Fundamental Research Funds for the Central Universities (No.B210202050)the Scientific Research Project of Jiangsu Communications Holding Co.,Ltd (No.JETC-DLJS-2022-001)。
文摘Asphalt extraction test and scanning electron microscopy(SEM) were used for analysis of agglomerations of reclaimed asphalt pavement(RAP) particles. In order to quantify the agglomeration degree of RAP, the fineness modulus ratio(FMR) and the percentage loss index(PLI) were proposed. In addition, grey correlation analysis was conducted to discuss the relationship between particle agglomerations and RAP size,asphalt content(AC), and surface area. Two indexes indicate that the agglomeration degree increases in general as the RAP size reduces. This can be attributed to that particles are prone to agglomeration in the case of higher AC. Based on the SEM images and the material composition of RAP, the particle agglomeration in RAP can be classified into weak agglomeration and strong agglomeration. Grey correlation analysis shows that AC is the crucial factor affecting the agglomeration degree and RAP variability. In order to produce consistent and stable reclaimed mixtures, disposal measures of RAP are suggested to lower the AC of RAP.
基金Under the auspices of National Natural Science Foundation of China (No. 41071088)National Social Science Foundation of China (No. 08BJY056)
文摘Dalian, Shenyang, Changchun and Harbin are the four core cities which play an essential role in terms of promoting the economic development in Northeast China. In this paper, the impact of urban agglomeration on labor productivity is explored by making comparisons among these four cities. The model used for analysis is a classical model derived from previous studies. Some indicators, such as population density and economic density, were selected to examine the impact of urban agglomeration on the labor productivity based on the time-series data for the four cities from 1990 to 2007. The four main conclusions are： l） The promotion from the growth rate of population density on the growth rate of labor productivity is limited. 2） The negative relationship exists between the growth rate of employment density and the growth rate of labor productivity. 3） Agglomeration effect exists in the four cities, the highest one is Dalian, Shenyang takes the second place, followed by Changchun and Harbin, and the predominant promotion exerted on the labor productivity is the output density.
基金Financial support by project of China Petroleum Engineering Corp., Ltd (CPEC), Study on microstructural regulation of polyacrylate and applying as pour-point depressant for crude oil (2021ZYGC-01-01)。
文摘The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobicmodified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly(octadecyl, docosyl acrylate) and poly(acrylate-α-olefin) onto the surface of nano-sized SiO_(2) were synthesized by grafting polymerization method.The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM) and thermogravimetric analysis(TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO_(2) nanoparticle(PDA@SiO_(2)) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20℃, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules,thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO_(2) hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.
基金supported by the National Natural Science Foundation of China (Grant No.52475405,52471164,and 52231004)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University (No.CX2022039).
文摘The mechanical properties of graphene reinforced composites are often hampered by challenges related to the dispersion and aggregation of graphene within the matrix.This paper explores the mechanism of cooling rate,process temperature,and process pressure’s influence on the agglomeration behavior of graphene and the tensile response of composites from a computer simulation technology,namely molecular dynamics.Our findings reveal that the cooling rate exerts minimal influence on the tensile response of composites.Conversely,processing temperature significantly affects the degree of graphene aggregation,with higher temperatures leading to the formation of larger-sized graphene clusters.In contrast,processing pressure exhibits negligible impact on the degree of graphene aggregation,and increasing pressure effectively mitigates the formation of large-sized graphene clusters.Moreover,we elucidate the intrinsic factors governing the mechanical response to variations in processing parameters.Notably,we observe that the stretching process facilitates the decomposition of large-sized graphene clusters into smaller ones.This research contributes to the advancement of lightweight metal matrix composites by offering insights into optimizing processing parameters.Additionally,it provides crucial theoretical underpinnings for developing high-performance graphene-reinforced composites.
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:3052017010。
文摘Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.
基金Under the auspices of the Humanities and Social Sciences Fund of the Ministry of Education of China (No.20YJC790107)Planning Project for Philosophy and Social Sciences of Shanxi Province (No.2021YJ040)Special Foundation for Science and Development of Shanxi Province (No.202204031401052)。
文摘It is of importance to enhance the urban areas'capacity for population aggregation in underdeveloped regions,aiming to rectify the imbalanced and insufficient pattern of economic development in China.Taking the Taiyuan Metropolitan Area(TMA)in central China as a case study,this paper examines the evolutionary process and characteristics of population agglomeration from 2000 to 2020,and identifies factors associated with agglomeration and their spatial effects.The findings indicated that:1)against the background of sustained population shrinkage in the provincial area,the TMA showed a demographic trend of steady increase,albeit with a decelerated growth rate.In the metropolitan area,urban population size continued to grow rapidly,whereas the rural areas endured sustained losses.Disparities in city size continued to widen,and the polarization of concentrated population in the core cities kept increasing.2)Agglomerations in both secondary and service industries had significant positive effects on local population agglomeration,with the former effect being stronger.Regional economic development,government fiscal expenditure,and financial advancement all contributed to facilitating local population clustering.From a spatial spillover perspective,service agglomeration and financial development promoted population agglomeration in surrounding areas.Conversely,fiscal expenditure inhibited such agglomeration.As for industrial agglomeration and regional economic development,their spatial spillover effects were non-significant.The results obtained reveal several policy implications aimed at enhancing the population agglomeration capacity of the metropolitan area in underdeveloped regions during the new era.
基金Under the auspices of National Natural Science Foundation of China(No.72373094,72303149)Scientific Research Start-up Funds of Guangdong Ocean University(No.060302082319)。
文摘High-quality development is the primary task of comprehensively building a socialist,modern country,as well as the primary task of building urban agglomerations in China.Based on the five development concepts,this paper used the entropy method to measure the High Quality Development Index(HQDI)of the five major urban agglomerations.The results showed that the HQDI of the five major urban agglomerations shows a fluctuating upward trend.First,using the Dagum Gini coefficient to explore the sources of HQDI development differences in urban agglomerations,we found that the main source of HQDI differences in urban agglomerations was inter-regional differences,while intra-regional differences were not important.Second,kernel density estimation was used to test the dynamic evolution trend of HQDI within urban agglomerations.There was a polarisation phenomenon in the HQDI of urban agglomerations,such as the Pearl River Delta urban agglomeration and the Chengdu-Chongqing urban agglomeration.But overall,the degree of imbalance had decreased.Third,using geographic detectors to examine the driving factors of HQDI in urban agglomerations,we found that the main driving forces for improving HQDI in urban agglomerations were economic growth,artificial intelligence technology and fiscal decentralisation.All the interaction factors had greater explanatory power for the spatial differentiation of HQDI,which can be divided into two types:two-factor improvement and non-linear improvement.This study is conducive to improving and enriching the theoretical system for evaluating the high quality development of urban agglomerations,and provides policy references for promoting the high quality development of urban agglomerations.
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supported by the 2021 Research and Practice Project of Higher Education Teaching Reform in Henan Province(Grant No.2021SJGLX072Y).
文摘Under the background of new infrastructure,the Yellow River Basin’s superior growth cannot be separated originating with the synergistic effect of scientific and technological inventiveness and ecological civilization construction.In light of the coupling coordination analysis of the coordination effect of provincial high-tech industry agglomeration and resource carrying capacity in the Yellow River Basin from 2009 to 2021,The evolution of the geographical and temporal pattern of development was investigated using the Moran index and kernel density estimation.The results show that the agglomeration of high-tech industries in the Yellow River Basin presents a development trend of seek improvement in stability,and there is a good coupling and coordination throughout the progression of scientific and technological innovation and the loading capacity of the resource,from the viewpoint of a time series.From the perspective of spatial pattern distribution,the whole basin aims at the lower reaches,accelerates the optimization of digital industry and promotes Yellow River Basin development of superior quality through innovation support and increase of input,and based on policy guidance.
基金Under the auspices of National Natural Science Foundation of China(No.42276234)National Social Science Foundation Major Project of China(No.23&ZD105)+1 种基金the Open Fund of the Key Laboratory of Coastal Zone Exploitation and Protection,Ministry of Natural Resources of China(No.2023CZEPK04)the Science and Technology Major Project of Ningbo(No.2021Z181)。
文摘Urban agglomerations,serving as pivotal centers of human activity,undergo swift alterations in ecosystem services prompted by shifts in land utilization.Strengthening the monitoring of ecosystem services in present and future urban agglomerations contributes to the rational planning of these areas and enhances the well-being of their inhabitants.Here,we analyzed land use conversion in the Yangtze River Delta(YRD)urban agglomeration during 1990-2020 and discussed the spatiotemporal response and main drivers of changes in ecosystem service value(ESV).By considering the different development strategic directions described in land use planning policies,we predicted land use conversion and its impact on ESV using the Future Land Use Simulation(FLUS)model in three scenari-os in 2025 and 2030.Results show that:1)from 1990 to 2020,land use change is mainly manifested as the continuous expansion of con-struction land to cultivated land.Among the reduced cultivated land,82.2%were occupied by construction land.2)The land use types conversion caused a loss of 21.85 billion yuan(RMB)in ESV during 1990-2020.Moreover,the large reduction of cultivated land area led to the continuous decline of food production value,accounting for 13%of the total ESV loss.3)From 2020 to 2030,land use change will mainly focus on Yangzhou and Zhenjiang in central Jiangsu Province and Taizhou in southern Zhejiang Province.Under the BAU(natural development)and ED(cultivated land protection)scenarios,construction land expansion remains dominant.In contrast,under the EP(ecological protection)scenario,the areas of water bodies and forest land increase significantly.Among the different scenarios,ESV is highest in the EP scenario,making it the optimal solution for sustainable land use.It can be seen that the space use conflict among urban,agriculture and ecology is a key factor leading to ESV change in the urban agglomeration of Yangtze River Delta.There-fore,it is crucial to maintain spatial land use coordination.Our findings provide suggestions for scientific and rational land use planning for the urban agglomeration.
基金Under the auspices of National Natural Science Foundation of China(No.71172213,71171183)Ministry of Educa-tion,Humanities and Social Sciences Project(No.09YJA630153,10YJA790260)+1 种基金National Social Science Foundation of China(No.08&ZD043)Australian Research Council,and Chinese Academy of Sciences(CAS)Special Grant for Postgraduate Research,Inno-vation and Practice
文摘This paper falls into the broad area of economic geography and economics of creativity,and it presents an alternative approach to explain why total factor productivity(TFP)growth is different across China′s regions.It establishes an empirical model to estimate the spatial agglomeration effects of creative industries on regional TFP growth,using China′s provincial panel data during the period of 2003 to 2010.We found that the creative industries agglomeration(CIA)has significant and positive impact on regional TFP growth.The result also implies that the CIA can facilitate regional TFP growth through promoting regional innovation instead of improving regional efficiency.Therefore,we argue that policy makers should take some measures to retain and establish more creative zones.
基金Supported by Scientific Resarch Program of Humanities and Social Sciences launched by Hubei Provincial Department of Education(2009b530)~~
文摘Spatial structure of rural tourism in the urban agglomerations of Wuhan was analyzed by comprehensively studying relevant documents about rural tourism,and reviewing previous researches on the concept and spatial structure of rural tourism.Through investigating rural tourist resources in the study area,resource advantages and characteristics of 9 cities were introduced,and the Gini Coefficient was taken to quantitatively analyze spatial patterns of its rural tourist villages,the obviously imbalanced concentration of these villages was pointed out.By measuring connectivity and accessibility of regional spaces in the study area,its traffic connectivity was proved moderate,and accessibility of each tourist village and town was fine.Then an optimized spatial structure was proposed for the rural tourism development in Wuhan Urban Agglomerations,that is,"one core,one belt and three districts".
基金Supported by Agricultural Specific Fund Project of Hunan Provincial Department of Finance([2011]No. 10)~~
文摘[Objective] This paper aimed at studying the agglomeration and fluctuation situation of rice production in Hunan Province during the past 10 years.[Method] Data were collected from Hunan Rural Statistical Yearbook（2001-2010）.Taking the concentration index of sown area and production（CDI） and the volatility index（VI） as the main indicators,the agglomeration and fluctuation situation of paddy rice,early-season rice,middle-season rice and single-season late rice,late-season rice,good quality early-season rice,good quality middle-season rice and good quality single-season late rice,good quality late-season rice production in each major rice-producing area of Hunan Province during the past 10 years had been studied.[Result] The orders of concentration index of sown areas and production of paddy rice,early-season rice,middle-season rice and single-season late rice,late-season rice,good quality early-season rice,good quality middle-season rice and good quality single-season late rice,good quality late-season rice in Hunan Province varied,but the orders of volatility index were consistent.The stable areas,relatively stable areas and fluctuant areas in sown areas and production of different major rice-producing areas were defined.[Conclusion] The research had provided basis for optimizing the layout of rice production in Hunan Province,promoting agglomeration and development of rice production and translating the comparative advantages into the competitive advantages.
