Agglomeration Characteristics Research Articles

Spatio-temporal pattern and driving factors of tourism ecological security in Fujian Province

The scientific assessment of tourism ecological security holds significant theoretical and practical importance in promoting the sustainable development of the tourism economy and the ecological environment in the region. This study focuses on 84 counties within Fujian Province as its research scope. By utilizing the DPSIR model and integrating the remote sensing ecological index (RSEI), we have established an evaluation index system for assessing tourism ecological security in the region. The tourism ecological security index was quantitatively determined using the SBM-DEA model. Subsequently, a combination of methods, including spatial autocorrelation, exploratory regression analysis, and the GWR model, was employed to explore the spatial and temporal evolution patterns, as well as driving factors affecting tourism ecological security from 2010 to 2019. The findings reveal the following insights: (1) Overall, the level of tourism ecological security within Fujian Province is low, with a decreasing disparity in the security index across different regions. The tourism ecological security mainly falls within the “unsafe” and “relatively unsafe” categories; however, regions with higher security levels are exhibiting an expanding trend. Moreover, the tourism ecological security of each county is improving, with Southern and Central Fujian outperforming other regions. (2) Notably, there is significant spatial correlation among the tourism ecological security of each county in Fujian Province, indicating pronounced agglomeration characteristics. (3) Key drivers contributing to the spatial–temporal disparities in tourism ecological security encompass tourist-related disturbances, income levels of local farmers and herders, tourism-generated income, and government interventions. Among these factors, higher income levels for farmers and herders, increased tourism income, and proactive government intervention have a positive impact on tourism ecological security, whereas tourist disturbances exert a negative influence. Additionally, the impact of each factor on tourism ecological security displays noticeable spatial heterogeneity.

Optimization of product characteristics of porous carbon agglomerates using a design of experiments in fluidized bed agglomeration

Spraying parameters during particle agglomeration processes can affect the agglomeration kinetics and particle growth. This study was conducted to better understand the influence of the spraying parameters in a fluidized bed wet agglomeration process, and the influence on the stability characteristics of carbon tablets. A formulation based on fine carbon and peroxide powder, as well as carboxymethyl cellulose as a binder, was used to produce agglomerates in a first production step. Thereafter in a second production step carbon tablets with a high porosity were molded for the customer goods industry. The optimization of the compressive strength of these carbon tablets was the goal of the trials. Carbon agglomerates were produced with a laboratory scale granulator called “ProCell” and were compressed with a five-cavity mechanical press. The screening of the agglomeration process parameters and their influence on the agglomerates quality, as well as the performance characteristics of the carbon tablets, were investigated using a multilevel factorial design. The experimental runs were done by varying atomized air pressure and feed rate of the fluid. This was determined by the design model. The findings of the statistical trials showed that low atomized air pressure and a low feed rate lead to a higher tablet compressive strength.

Measurement and characteristics of the temporal-spatial evolution of China’s healthcare services efficiency

BackgroundHealthcare services efficiency (HSE) is directly related to the healthcare demands of the general public and also plays an essential role in the country’s coordinated economic and social development.MethodsIn this study, the stochastic frontier approach (SFA)-Malmquist model was applied to measure the HSE of 31 Chinese provinces based on panel data from 2010–2020. Then, kernel density estimation, Markov chain, and exploratory spatial data analysis were adopted to study the temporal-spatial dynamic evolution characteristics of the HSE.ResultsThe study found that China’s HSE showed an average value of approximately 0.841, indicating room for improvement. The HSE varied significantly across regions, presenting an “East > Central > West” distribution layout. The TFP of healthcare services in China grew by 1.6% per year, driven mainly by technological progress of 1.8% per year. The trend of the HSE shifting to a high level in China was significant, but its evolution exhibited stability of maintaining the original state, and it was harder to achieve leapfrog transfer. The temporal-spatial evolution of the HSE was also significantly affected by geospatial factors, with a clear spatial spillover effect and spatial agglomeration characteristics. Provinces with high-level HSE exhibited positive spatial spillover effects, while provinces with low-level HSE had negative spatial spillover effects. Thus, the “club convergence” phenomenon of “high efficiency concentration, low efficiency agglomeration, high levels of radiation, and low levels of suppression” was formed in the spatial distribution.ConclusionsThe results indicate that countermeasures should be taken to improve the HSE in China. Theoretical support for the improvement of HSE is provided in this paper.

Aluminum particle agglomeration characteristics and suppression method during the combustion of aluminum‐based solid propellants: A review

AbstractAluminum is widely used in solid rocket propellants to improve the energy performance of the propellant. However, during propellant combustion, aluminum particles may agglomerate, resulting in slag deposition, incomplete combustion of metal particles, increased two‐phase flow losses, and reduced motor specific impulse. Therefore, it is of great scientific significance and engineering value to understand the agglomeration mechanism of aluminum particles and to explore the method of agglomeration suppression. Based on this, this paper firstly briefly introduced the agglomeration process of aluminum particles during propellant combustion. Subsequently, factors influencing the agglomeration of aluminium particles were analysed. The influencing factors can be roughly divided into two aspects: propellant‘s own formulation and external environment. Immediately afterwards, the existing agglomeration suppression methods were emphasized and summarized and analyzed. Presently, agglomeration suppression methods can be broadly classified into four categories, namely, conventional formulation optimization, use of aluminum nanoparticles, and modification of aluminum particles using fluorine‐containing compounds or alloy particles. Finally, several directions that need to be focused on in the future are proposed to address the problems in the study of aluminum particle agglomeration suppression methods.

Evolution and spatial reconstruction of rural settlements based on composite features of agglomeration effect and ecological effects in the Hexi Corridor, Northwest China.

Rural reconstruction plays a pivotal role in the revitalization of rural areas and the development of regions. Understanding the pattern and direction of rural settlement reconstruction is crucial for effectively coordinating urban and rural development, as well as promoting regional rural revitalization. The present study proposes a novel approach to elucidate the evolution and spatial reconstruction of rural settlements by integrating features of agglomeration effect and ecological effect. By employing GIS spatial analysis technology and ecosystem service value modeling, the research analyzes the combined spatial agglomeration and ecological value characteristics of rural settlements in an arid oasis area, specifically focusing on the Hexi Corridor. Based on the analysis, the study identifies specific rural settlement reconstruction zoning and directions for optimization, considering rural settlement accessibility. The study reveals three key findings: (1) There are significant differences in the scale density and spatial distribution of rural settlements across the Hexi Corridor. (2) The overall ecological environment quality is good, and there is significant spatial differentiation in the ecosystem service value, influenced by topographic factors. (3) The optimal layout mode for rural settlements in the Hexi Corridor is the combination type of 'higher-ecological higher-density'. Based on the combined agglomeration effect and ecological effect features, the research determines the reconstruction scope of alienated rural settlements. Additionally, four predominant reconstruction modes are identified: urban agglomeration type, central village construction type, internal coordination type, and ecological protection type. The study proposes viable reconstruction paths for rural settlements based on these modes.

The impact of rice-crayfish field on socio-ecological system in traditional farming areas: Implications for sustainable agricultural landscape transformation

Agricultural landscape transformation has profound impacts on regional sustainable development. Understanding the relationship between agricultural landscape transformation and socio-ecological system is fundamental to both social prosperity and ecological environment. Rice-crayfish field (RCF) as a unique agricultural model is widely practiced in traditional farming areas and causes significant landscape transformation. However, the RCF remains less understood and its impacts on socio-ecological systems need to be comprehensively investigated. China has a developed crayfish industry with over 90% of the world's crayfish production, which provides an interesting lens to examine the RCF-led agricultural landscape transformation. This research proposes a novel research framework to analyse the spatial dynamic of RCF and its complex impact on socio-ecological system. Using remote sensing and geospatial data analysis, this study explores the spatiotemporal heterogeneity of RCF-led landscape transformation and socio-ecological system. In addition, the impacts of RCF on socio-ecological system are examined by the Pearson correlation analysis, root mean square error and regression model. The results reveal that RCF has dramatically expanded and transformed from paddy fields. The socio-ecological system presents obvious spatial agglomeration characteristics. RCF has the potential to increase farmers' income and alleviate rural poverty, but it is not conducive to grain production and water consumption. The RCF-led agricultural landscape transformation could be a double-edged sword to socio-ecological system. To balance social and ecological systems, it is necessary to manage and design the rational development of RCF to support sustainable agricultural landscape transformation.

Dynamic volatility spillover among cryptocurrencies and energy markets: An empirical analysis based on a multilevel complex network

Based on the DCC-GARCH-CONNECTEDNESS approach, this paper investigates the dynamic volatility spillover among ten cryptocurrency markets and three energy markets. This study constructed a volatility spillover network weighted by the spillover intensity index. The overall network topological properties, node characteristics, and spillover structure were then analyzed by applying the index quantification and hierarchical clustering algorithm. This research examined the multi-level risk spillover structure while realizing network visualization and also judged the dynamic correlation among the spillover network structures. The findings show that the network topology properties are relatively stable, but there is a large heterogeneity among markets. Compared to the energy market, the cryptocurrency market exhibits more profound features of volatility resonance between different currencies. Traditional cryptocurrency markets display higher risk resonance levels than stable coins. In terms of risk spillover structure, different markets tend to rely on market attributes to demonstrate their spillover and agglomeration characteristics. In addition, the risk spillover resonance among the sub-networks is also dynamic and time-varying, and this network structure will continue over time.

Effect of carbon dioxide concentration on the combustion characteristics of boron agglomerates in oxygen-containing atmospheres

Effect of carbon dioxide concentration on the combustion characteristics of boron agglomerates in oxygen-containing atmospheres

Towards a low-carbon society: spatial distribution, characteristics and implications of digital economy and carbon emissions decoupling

Reducing carbon emissions and attaining sustainable economic, social, and environmental development are vital components of the 2030 Agenda for Sustainable Development. Previous research has overlooked the influence of the digital economy on urban carbon decoupling. To bridge this gap, this study employs GIS software and econometric models for analyzing the spatial distribution and characteristics of the digital economy and carbon decoupling and also investigates the direct, heterogeneous, and spatial effects of the digital economy on carbon decoupling. This study reveals: (1) A lesser digital economy presence in the northeast and northwest, while more developed in the Southeast Coast and municipalities directly under the Central Government. Cities with weak carbon decoupling are concentrated in Northeast and North China. (2) The digital economy and the decoupling of urban carbon emissions have spatial correlation and agglomeration characteristics. (3) The digital economy can contribute to decoupling carbon emissions in cities. (4) Improved urban carbon decoupling by the digital economy in central, eastern, and non-resource-based cities. (5) Spatial spillover effect in urban carbon emissions decoupling, yet the digital economy worsens nearby cities’ carbon decoupling due to a siphon effect. That research indicates that the digital economy holds significant promise not only in advancing human progress, bridging the digital divide, and fostering social development but also in driving the decoupling of urban carbon emissions.

Effect of external electric field on agglomeration characteristics of Cu nanoparticles: A molecular dynamics study

In order to study the effect of electric field on the stability of Cu nanoparticles in water, molecular dynamics method was used to simulate the agglomeration characteristics of Cu nanoparticles. The microscopic agglomeration characteristics of nanoparticles by electric field were analyzed using the distribution and collision of nanoparticles in water at different times, as well as the potential energy, kinetic energy, diffusion coefficient and radial distribution function of the system. The results show that the collision of Cu nanoparticles was inhibited in the presence of both uniform and alternation electric fields. The total potential energy of the system decreases with each collision of particles. When all of the particles are agglomerated, the total potential energy of the system remains constant. According to the radial distribution function, when the electric field intensity increases, the degree of aggregation of water molecules on the particle surface strengthens and then weakens as the electric field strength. Meanwhile, the degree of aggregation decreases with the increasing frequency of the alternating electric field. The effect of electric field frequency on the diffusion coefficient of nanofluid is insignificant. However, as the strength of the electric field increases the diffusion coefficient of the nanofluid decreases, while the resistance coefficient of water molecules increases, and the presence of the electric field inhibits the movement of water molecules. The influence of electric field on the heat transfer and deposition characteristics of nanofluids can be obtained by experiments, but the influence mechanism is difficult to be analyzed by experimental means. The molecular dynamics method also provides a new idea to reveal the influence mechanism of electric field.

Thermal behavior and laser-induced heating characteristics of boron agglomerates in various atmospheric conditions

Thermal behavior and laser-induced heating characteristics of boron agglomerates in various atmospheric conditions

Correlation between carbon emissions and water consumption in different industries in China: Spatial and temporal distribution characteristics and driving factors

In order to quantitatively analyze the correlation between carbon emissions and water consumption and identify the main driving factors. Energy consumption and water consumption data of different industries in different provinces of China were collected to calculate the water consumption per unit of carbon dioxide emissions (WCCD) and analyze the characteristics of its spatial and temporal distribution, as well as spatial correlation. The driving factors of WCCD change were quantitatively analyzed by correlation analysis and principal component analysis methods. The results showed that: (1) From 2000 to 2020, WCCD values in each province gradually decreased and approached a plateau. The overall spatial distribution showed more concentration in the south and less in the north, with the North Coastal Economic Zone showing lower values. (2) The spatial correlation of WCCD values is positively correlated, that is, WCCD values have agglomeration characteristics. The WCCD values are mainly ‘high-high aggregation’ and ‘low-low aggregation, which suggests a significant convergence trend and serious polarization. (3) Per capita GDP, per capita energy consumption, and urbanization rate showed an extremely strong correlation with WCCD, while the proportion of the tertiary industry in GDP showed a strong correlation with WCCD. Per capita water resources showed a weak correlation with WCCD. The principal component analysis revealed an increasing impact of economic development on WCCD indicators. This study provides a new perspective for carbon-water relationship research and serves as a fundamental support for water-saving and emission reduction measures.

Mechanism and evolution trend of digital green fusion in China's regional advanced manufacturing industry

This paper has observed pivotal changes in innovative frameworks at the intersection of the digital revolution and sustainable initiatives. Within Industry 4.0, the fusion between intelligent manufacturing and green innovation has become a central driver for sustainability. Integrating these two pivotal forces to harness their collective efficiency is crucial. However, current literature offers limited insights into their combined impact, and the direction of their evolving trends still needs to be defined. Considering this, the research elucidates the core concepts and traits of digital-green fusion (DGF) within regional advanced manufacturing (RAMIDGF). Moreover, this research proposes a double-helix fusion mechanism model. Utilizing data from the advanced manufacturing sectors in six key Chinese urban clusters, this paper adopts a comprehensive analytical toolkit that includes the Coupling Modified Model, Kernel Density Estimation, Markov Chain algorithms, and the Dagum Gini Coefficient for trend analysis. The findings indicate that between 2009 and 2021, RAMIDGF exhibited a trend of initial growth followed by a decline, showing a strong correlation with per capita GDP (RGDP). The principal source of variation in RAMIDGF stems from differences between urban agglomerations, with the Yangtze River Delta and the Beijing-Tianjin-Hebei clusters exhibiting transitional behavior and a ‘ladder-type trend’ in RAMIDGF. As metropolitan clusters become more economically integrated, the probability of transitional behavior in RAMIDGF heightens. However, achieving elevated leapfrog development proves challenging, with an inherent risk of decline. Spatial spillover implications, agglomeration characteristics, and club convergence tendencies mark the RAMIDGF process. These findings expand upon new paradigms for regional sustainable development, offering novel avenues for realizing high-quality growth.

Study on the Spatial Structure of the Complex Network of Population Migration in the Poyang Lake Urban Agglomeration

Population constitutes the foundational element of cities, and population migration drives the transfer of production factors among urban areas. The population migration network serves as an objective representation of intercity interactions, bearing great significance for the analysis of urban network spatial structure. This study focuses on the 10 core cities within the Poyang Lake urban agglomeration. It utilizes population migration data from Tencent’s location-based big data spanning from 2015 to 2018. Employing the point-axis theory from spatial network theory and the directed weighted network theory within the complex network, the study establishes a comprehensive set of network indices and a network model for spatial structure. It investigates the dynamics of population migration networks within the urban agglomeration and considers strategies for enhancing, regulating, or guiding urban agglomeration development to strengthen its overall vitality. The findings indicate that the urban agglomeration displays distinct characteristics of an urban hierarchical sequence and demonstrates gradual improvement in its spatial network development. While network density remains relatively stable across various threshold intervals over an extended period, network connectivity remains weak. Moreover, the urban agglomeration exhibits the lowest degree of centralization, the highest network structure entropy, and limited network connectivity. Migration along the primary power axis within the urban agglomeration remains relatively stable, while the internal network of the urban agglomeration is interconnected through a “core-non-core” network, reflecting near-geographical connection characteristics. Variations in spatial structure are observed, with the spatial network structure following two modes: “weak core city + edge city” and “node city + outer network city”. The trend in network connections diversifies, resulting in both “core-edge” connections and cross-regional connections. In conclusion, the network characteristics of the urban agglomeration surrounding Poyang Lake are consolidated to aid in formulating an optimization plan for the urban agglomeration’s spatial structure. Additionally, these findings serve as a reference for studying the evolution of spatial structures in the other two urban agglomerations within the city agglomeration in the middle reaches of the Yangtze River.

Influence mechanism of dispersion and agglomeration characteristics of micron/nano carbon dust on its combustion kinetics and explosion process

Due to the widespread use of lithium-ion batteries, evaluations of the flammability and explosive characteristics of carbon dust materials as anodes require attention. Carbon dust often reaches the micron/nano scale, and dust particle state and explosion risk generated in different industrial scenarios are different, which is in urgent need of research. Nanoscale dust has relatively static coagulation properties and shows characteristics of dispersion and reagglomeration under a certain airflow. The particle size characteristics affect its thermodynamic characteristics and various consequence parameters of dust explosion. The oxidation and combustion characteristics are mainly affected by dust particle size distribution characteristics. The apparent activation energy is mainly affected by the proportion of small and medium-sized particles and pre-exponential index factor is mainly affected by the dust overall average particle size and specific surface area. The explosion consequence parameters are affected by the thermodynamic parameters, by the disturbance state, particle distribution degree of dust cloud and other factors, which affect the heat radiation and heat transfer process to some extent resulting in different explosion consequence parameters. Due to the agglomeration characteristics of nano-level dust, the minimum ignition energy and minimum ignition temperature of nano-level dust are generally smaller than that of micron level dust.

Controlling the combustion and agglomeration characteristics of solid propellants via new micro-unit composite fuel Al@AP

New micro-unit composite fuels Al@AP with different mass ratios of Al and AP are designed, prepared, and added to solid propellants in place of the original aluminum powder. Through Thermogravimetric Analysis- Differential scanning calorimetry- Mass Spectrometry (TG-DSC-MS), laser ignition experiment, thermocouple temperature measurement, burning rate test, and combustion diagnostic, we study how Al@AP affects the ignition, combustion, and agglomeration properties of solid propellants. The results indicate that the increase of Al content of Al@AP can promote the advance of thermal decomposition of AP. As the AP content increases in Al@AP, the ignition delay time of Al@AP decreases by three times, and the mass burning rate increases by almost five times. At the same time, Al@AP significantly improves the burning rate and temperature gradient. When compare to the baseline propellant, Al@AP-containing propellants present a maximum increase in burning rate of 33% at low pressures and 19% at high pressures. In terms of agglomeration reduction, the number of large-size agglomerates in the CCPs of propellants containing Al@AP is reduced, the average particle size decreases by 78%, and the combustion efficiency increases to 99.34%. A mechanism is proposed to explain how the micro-unit composite fuel Al@AP alters propellant combustion and agglomeration. In summary, Al@AP provides excellent control over ignition, combustion, and agglomeration characteristics. This study provides guidance on the application and development of new aluminum-based composite fuels used in solid propellants.

The Impact of Agricultural Insurance on Urban–Rural Income Gap: Empirical Evidence from China

Based on the panel data of 31 provinces in China from 2005 to 2020, this paper analyzes the mechanism and spatial spillover effect of agricultural insurance on the urban–rural income gap using a fixed effect model, an intermediary effect model, and a two-stage least square method. The results show that agricultural insurance has a significant inhibitory effect on the income gap between urban and rural areas. This inhibitory effect is realized through the path of “improving the development level of agricultural insurance-improving agricultural total factor productivity-reducing the income gap between urban and rural areas”, in which the intermediary effect of agricultural total factor productivity accounts for 19.74% of the total effect. At the same time, the income gap between urban and rural areas in China exhibits typical spatial agglomeration characteristics. The western region has always been the region with the largest income gap between urban and rural areas, while the eastern region is the region with the smallest income gap between urban and rural areas. The development of agricultural insurance has had a spatial spillover effect on the income gap between urban and rural areas, and the development of agricultural insurance in neighboring areas expands the income gap between urban and rural areas in this region. In order to prevent the siphon effect, agricultural insurance investment should be increased in the neighboring regions. The results of this paper support the view of the resource flow model. Finally, we put forward some suggestions for the development of agricultural insurance, improvement in agricultural total factor productivity, and the narrowing of the income gap between urban and rural areas.

Retracted: Research on Spatial Agglomeration Characteristics of Aerospace Cultural and Creative Industries in Smart City under Multidata Fusion

Retracted: Research on Spatial Agglomeration Characteristics of Aerospace Cultural and Creative Industries in Smart City under Multidata Fusion

Spatial and temporal variations of landscape ecological risk in the dry and hot valley of the Jinsha River during 2000-2020

Scientific assessment of landscape ecological risk in ecologically fragile areas of the upper reaches of the Yangtze River is of great significance to regional ecological regulation and construction of the Yangtze River ecological security barrier. With the dry-hot valley area of Jinsha River in Yunnan Province as the research area, we constructed a landscape ecological risk evaluation model, and analyzed the spatial and temporal variations of regional landscape ecological risk. The results showed that the average values of landscape ecological risk index (LER) in the study area were 0.414, 0.398, and 0.462 in 2000, 2010 and 2020, respectively. The LER value of the whole region had reached a higher risk level by 2020. In 2000 and 2010, the landscape ecological risk zones of each level were staggered, and the high-risk zones showed a centralized distribution in 2020. During the two decades, the average LER of each section in the study area was around 0.42, which was close to the high risk level, indicating high landscape ecological risk level. The area of middle and low risk zones had decreased, while the area of high risk zone had significantly increased. The area of high risk zone in the western and middle sections was much higher than that in the eastern section. The area with significant changes of landscape ecological risk accounted for about 55% of the total study area, with obvious spatial agglomeration characteristics of significant increase and decrease of risk. The competition between government-led ecological management policies and measures and market-led land use activities was the main cause of landscape ecological risk variations in this region. In the future, the driving mechanism of climate change coupled with human activities on global and local landscape ecological risk changes in the study area should be uncovered to effectively cope with regional ecological risks.

Research on the spatial-temporal evolution pattern of China's industrial carbon emission efficiency-based on the super-efficiency SBM model

This paper uses the super efficiency SBM model based on unexpected output to calculate the industrial carbon emission efficiency of 30 provinces in China from 2005 to 2019, and uses spatial autocorrelation and other methods to conduct an empirical analysis on the dynamic evolution process and temporal and spatial differences of carbon emission efficiency. The results show that China's industrial carbon emission efficiency is still in the low efficiency stage, with an average value of 0.34. In the study period, although the overall trend is rising, the spatial and temporal differences between provinces are obvious. The overall Moran's I index is subject to the impact of social policy environment on the time path, showing an overall "M" type fluctuation trend, and its spatial difference characteristics change in stages. At the same time, there is a significant global spatial agglomeration effect across the country, and there is a spatial dependency between provinces. The agglomeration trend is significant, forming a cluster with the eastern coastal area as the high value center, and the northwest inland area as the low value center. The Getis OrdGI * index reveals that the local spatial agglomeration characteristics of China's industrial carbon emission efficiency always maintain the pattern of "hot in the east and cold in the west", which echoes the overall spatial evolution pattern of China. The hot spots and sub hot spots of China's industrial carbon emission efficiency are mainly concentrated in the southeast coastal areas with relatively superior economic development, and present a "semi enclosed" pattern. Cold spot area and sub cold spot area gradually evolved into a "suppression" pattern dominated by provinces in northwest China, comprehensively suppressing hot spots. This paper conducts an all-round evaluation of China's industrial carbon emission efficiency from the perspective of regional differentiation, and deeply studies the regional differences and spatial evolution pattern of carbon emission efficien cy in various provinces. It is crucial to achieve the goal of carbon emission reduction in China, and has important practical value and practical significance.