Particle agglomeration and inhibition method in the fluidized pyrolysis reaction of waste resin

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.

Agglomeration of coal and polyethylene mixtures during fixed‑bed co‑gasification

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.

Evaluation and Influencing Factors on Particle Agglomeration in RAP

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.

A new fluorocarbon adhesive:Inhibiting agglomeration during combustion of propellant via efficient F-Al_(2)O_(3) preignition reaction

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.

Evolution and Determinants of Population Agglomeration in Less Developed Metropolitan Areas:A Case Study of the Taiyuan Metropolitan Area,China

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.

Dynamic Development Characteristics and Driving Factors of High Quality Development Level in China’s Five Major Urban Agglomerations

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.

Analysis of Urban Agglomeration Network Structure Based on Baidu Migration Data: A Case Study of the Guangdong-Hong Kong-Macao Greater Bay Urban Agglomeration

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.

Spatio-temporal evolution of the coordinated development of high-tech industry agglomeration and resource-environmental carrying capacity in the Yellow River Basin

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.

Land Use Dynamics and Ecosystem Service Value Changes in the Yangtze River Delta Urban Agglomeration Under Different Scenarios

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.

流通业集聚对农业韧性的影响

提升农业韧性是加快推进农业强国的重要内容。面对资源环境约束、人口红利衰减等诸多问题,深入分析流通业集聚对农业韧性的影响,有助于提升供应链效率,推进农业供给侧结构性改革,夯实国家粮食安全根基。以2008—2020年省级面板数据为样本,通过熵值法和区位熵测算农业韧性和流通业集聚程度,采用空间杜宾模型和门槛效应模型进行实证分析。研究发现,流通业集聚与农业韧性存在显著空间关联性,且具有空间集聚特征。流通业集聚对农业韧性存在空间溢出效应。在溢出效应下,流通业集聚不仅对本地区农业韧性存在促进作用,对周边地区也存在积极影响。受到流通业集聚程度影响,流通业集聚对农业韧性的影响在东部地区比较明显,中部地区次之,在西部地区不明显。流通业集聚对农业韧性的影响存在门槛效应,当流通业集聚程度低于门槛值0.803时,存在促进作用;当越过门槛值0.803时,促进作用显著提升。基于此,要进一步发挥流通业集聚效应,加快建设高效的农村现代流通体系,同时要促进地区间合作交流,加强农产品流通枢纽建设,继续为农业发展蓄势赋能。

农业产业集聚对农业碳排放的影响——基于环境规制的调节效应研究

利用2003—2020年中国31个省份的面板数据,通过构建回归方程模型并运用协整检验、系统GMM方法研究了农业产业集聚对农业碳排放的影响以及环境规制所发挥的调节效应。结果发现:在国家层面,农业碳排放受到农业产业集聚的影响显现出“非线性关系”,即随着农业产业集聚程度的上升,农业碳排放总量呈先上升后下降的倒“U”型特征,并且在农业产业集聚对农业碳排放的影响中显著受到了环境规制的调节效应;而在地区层面,东部、中部和西部地区的农业碳排放均受到农业产业集聚的影响显现出先上升后下降的倒“U”型特征,但环境规制在农业产业集聚对农业碳排放的影响中的调节效应仅在东部和西部地区显著存在。

Study on Spatial Structure of Rural Tourism in Wuhan Urban Agglomerations

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".

基于改进DBSCAN空间聚类算法的北京市人工智能产业集聚格局研究

企业作为产业的重要主体,其发展直接表征着产业的发展,企业的空间格局对产业的发展及资源配置具有重要的引导意义。本文基于北京市工商注册在业的人工智能企业数据,提取企业注册地址并转化为地理位置信息,通过改进有噪声的应用背景下的基于密度的空间聚类算法(DBSCAN),分析北京市细粒度层级下人工智能产业集聚在全市域的空间分布格局特征。在DBSCAN算法改进方面,首先调整Minpts参数为企业注册资本总额与企业数量2个维度,企业数量大于5家且注册资本总额大于一定数额,为形成产业集聚区的2个必要条件;其次提取簇内位于边界的企业位置点作为集聚区地理边界点,将边界点连线并绘制形成人工智能产业集聚区。本文重点分析了企业注册资本和地理聚合半径对人工智能产业集聚区形成的影响,同时采用核密度估计法作为参照验证,表明改进DBSCAN方法具有精确刻画产业集聚区地理边界和确定不同规模产业集聚区的优势。通过分析得知,北京市人工智能产业集聚具有明显的中心分布特征,集中在城六区,呈现“两大龙头带动,北京市全域遍地开花”的分布情况,海淀区、朝阳区处于人工智能集聚程度高水平,相较其他区域,人工智能产业发展遥遥领先;西城区、东城区、丰台区、昌平区处于集聚程度较高水平;通州区、大兴区、平谷区、密云区、石景山区、房山区、门头沟区、怀柔区、顺义区处于集聚程度中等水平;延庆区集聚程度较低。通过改进DBSCAN算法精确定位出中关村区域、上地西二旗区域、五道口区域、望京区域、国贸区域、亦庄经开区等人工智能产业集聚区。进一步探究发现,海淀区的人工智能科研人才优势,朝阳区的信息技术领域企业基础,是两区人工智能发展突出的直接原因。延庆区等郊区远离北京市中心城区,产业资源匮乏,同时由于区域功能定位限制等原因,导致人工智能产业集聚水平较低,表明这些区域人工智能产业发展较为缓慢。

人口集聚对城市经济韧性的影响研究

伴随城乡二元结构的逐渐打破,人口自由流动产生的人口集聚成为影响城市经济韧性的重要因素。选取2012—2022年中国城市数据,在厘清人口集聚与城市经济韧性之间内在逻辑关系的基础上,实证检验二者间的因果关系及其存在的空间效应。研究结果表明:人口集聚对城市经济韧性具有显著的正向提升作用;人口集聚可以通过人力资本升级和产业多样化来间接提升城市经济韧性;不同地区的人口集聚对城市经济韧性的影响呈现出显著的区域异质性;人口集聚对城市经济韧性的影响具有空间外溢性,能够间接提升邻近城市的经济韧性。

金融要素集聚的绿色创新效应:空间关联特征与城市群异质性

区域绿色技术创新体系建设是经济绿色转型的重要基础,而金融要素空间集聚则充当着科技创新活动的重要加速器。现有文献围绕着金融要素集聚和绿色技术创新两条主线展开广泛讨论,也关注到金融要素集聚所内生的绿色创新效应,但较少基于城市群这一新时期区域协同发展的新型空间载体,系统考察两者的空间关联效应及其区域异质性特征。因此,选取国内十大代表性城市群,对其内部金融要素集聚和绿色技术创新的时空演变轨迹和空间关联异质性进行多维度诊断。研究发现:第一,金融要素集聚有助于通过各种空间效应加速城市群内部的绿色金融发展,进而正向驱动区域绿色技术创新水平的提升;第二,城市群范围内的金融要素集聚不仅会对区域绿色技术创新产生明显的本地促进效应,也会同时形成显著的空间溢出效果;第三,金融要素集聚对于绿色技术创新的空间效应还会受到城市群金融集聚模式、行政层级特征、经济发展状况等因素制约。有鉴于此,区域协同发展过程中,应围绕城市群发展定位构建差异化的金融要素集聚模式,因之打造契合于不同城市群现实约束的绿色金融服务体系和绿色技术创新体系;同时深度挖掘金融要素集聚对于绿色金融发展和绿色技术创新的空间传导效应及其异质性特征,推动金融改革和绿色发展的有效空间互动。

数字产业与制造业协同集聚对企业绿色创新的影响研究

基于马歇尔集聚经济理论,依据中国工业企业数据和城市面板数据,运用固定效应模型,考量数字产业与制造业协同集聚对企业绿色创新的影响。结果显示,数字产业与制造业协同集聚通过人力资本外部性、知识溢出效应机制促进企业绿色创新,但规模经济效应机制不成立,且该结果在更换核心变量指标、考虑极端值、替换固定效应及内生性问题后依然稳健。鉴于此,应因地施策,加快推动区域内数字产业与制造业协同集聚,提升软环境建设水平,促进企业绿色化发展。

区域旅游产业集聚对旅游经济韧性的影响及其空间效应研究——以长江经济带为例

科学洞悉区域旅游集聚对旅游经济韧性的影响及其空间效应,对提升区域旅游经济韧性和实现旅游经济高质量发展意义重大。文章构建区域旅游产业集聚影响旅游经济韧性的机理框架,以长江经济带11省市为案例地,采用区位熵和熵值法得到长江经济带旅游产业集聚度和旅游经济韧性水平,借助面板空间杜宾模型揭示出区域旅游产业集聚对旅游经济韧性的影响及其空间效应。结果表明:(1)研究期内,长江经济带旅游经济韧性水平整体呈上升趋势,且东部地区大于中西部地区,但存在明显的省际差异。长江经济带东部地区旅游经济韧性水平大于中西部,而中西部地区的旅游经济韧性水平增长率大于东部。(2)长江经济带省市旅游产业集聚水平整体上升,受旅游业在当地经济中的地位影响,呈现出西部高于中部,高于东部的格局。(3)区域旅游产业集聚对旅游经济韧性产生明显的正向空间效应,即区域旅游产业集聚不仅可以提升本省旅游经济韧性水平,并且可以产生显著的空间溢出效应来提升省周边区域的旅游经济韧性水平。

Research on the Agglomeration and Fluctuation Situation of Rice Production in Hunan Province

[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.

民用航空产业集聚对经济高质量发展的影响——基于省级面板数据的门槛回归模型检验

民用航空产业集聚是构建高端供求市场、高度产业协作、高度交通便利而实现区域资源优化配置与区域经济发展的重要因素。采用2009—2020年省级数据,探究民用航空产业的专业化集聚、多样化集聚和竞争效应3种集聚模式对区域经济高质量发展的影响,进一步检验集聚效应的阶段性作用。结果表明,随着集聚水平的上升,民用航空产业的专业化集聚与多样化集聚对区域经济高质量发展呈先抑制、后驱动的影响,竞争效应与区域经济高质量发展呈正相关关系。

生产性服务业与制造业协同集聚对城市创新的影响研究

强化国家战略科技力量,提升国家创新体系整体效能是当今中国加快进入创新型国家前列的重要命题。在构建城市创新质量新指标的基础上,运用空间误差模型和空间滞后模型就生产性服务业与制造业协同集聚对城市创新的影响机制进行深入剖析。研究结果显示:生产性服务业与制造业协同集聚能提升城市创新质量,并能通过推进产业结构高级化、提升城市科技投入水平和吸引研发人员流入三个渠道促进城市创新质量的提升,协同集聚对东部和中部地区城市创新质量有促进作用,高端生产性服务业和低端生产性服务业与制造业协同集聚均能促进城市创新质量提升。此外,生产性服务业与制造业协同集聚能够推动新企业注册量的递增,进而提升城市的创业积极性与创业活跃度。生产性服务业与制造业协同集聚具有促进城市创新质量和创业活力两大功能,可以成为推动城市高质量增长和提升城市竞争力的重要工具。