Agglomeration Effects Research Articles

The Impact of Factor Price Change on China’s Cotton Production Pattern Evolution: Mediation and Spillover Effects

Cotton is an important agricultural crop and strategic resource. China is currently the country with the largest global cotton production and consumption, but few studies have systematically analyzed the dynamic relationship between factor price change (FPC) and cotton production pattern evolution (CPPE). Based on provincial panel data from the main cotton planting areas from 1985 to 2021, this paper used spatial econometric models to empirically analyze the impact of FPC including labor price, production material cost, and mechanical cost on CPPE from the perspective of mechanical substitution difficulty. The findings are that (1) FPC significantly affected CPPE, specifically the rise of labor price induced the demand for mechanical substitution, resulting in a significant cotton agglomeration effect; (2) spatial econometric analysis found that FPC had a significant spatial spillover effect on CPPE in adjacent regions; and (3) the transfer analysis found that higher mechanical substitution difficulty exerted an inhibitory effect on cotton planting, leading to a gradual shift of the main cotton planting areas from the Yangtze River Basin and Yellow River Basin with high labor prices to the Northwest Inland region with lower labor prices. Updating the production technology and improving the efficiency of cotton specialization are effective strategies. The results are valuable for policy making related to the development of China’s cotton industry.

Experimental Study on Properties of Graphene and Hollow Glass Powder-Added Ultra-High Strength Concrete

A new ultra-high strength concrete, in which oxidized graphene nanoplatelet (GO) and hollow glass powder (HGP) are added, has been developed by authors. This paper presents the material properties of the concrete such as workability, compressive and tensile strengths, internal micro structure (SEM and MIP) as well as air-tightness which was tested using an equipment developed in this study. Test results show that workability and tensile strength significantly increase by a small addition of HGP, and that cGO (GO product of company c) and HGP are well dispersed without agglomeration effect, resulting in more than 20% of reduction in porosity. It is also observed that air-tightness increases by 40% compared with conventional ultra-high strength concrete due to reduction in porosity; thus, new ultra-high strength concrete is anticipated to be effectively used for structures that requires air-tightness such as hyperloop tube. Consequently, it was observed that the workability and mechanical properties of UHSC were increased when cGO and HGP were used instead of silica fume (SF), and authors believe that utilization of new material would contribute to the change in manufacturing method and increase in mechanical properties of concrete.

Ignition and combustion characteristics of magnesium-based nanofluid fuel

Mg-based nanofluid fuel is a promising fuel for propulsion system in Mars exploration. In this study, Mg-based nanofluid fuel were prepared by one-step method, and the effect of Mg(magnesium) content, Mg size(68 μm,110 μm,175 μm), and oleic acid (OA) on droplet ignition and combustion under the atmosphere of 90 % CO2 and 10 % O2 were investigated. According to the TG-DSC results, 68 m Mg particles under CO2 had the highest exothermic efficiency of 4472 J/g. The combustion of Mg/OA/kerosene droplets consists of five stages: ignition, d2-law combustion, micro-explosion, vapor flame extinguishment, and agglomerate explosion. The ignition delay time of Mg (68 μm, 5 %)/kerosene is 0.045s, which is half that of kerosene (0.0890s). The agglomerates explode violently and emit a brilliant white light at the end of the Mg-based nanofluid fuel combustion. The explosive effect of Mg agglomerates diminishes as the Mg content increases. The rate of combustion decreases with increasing particle size. In the sample with added oleic acid, Mg (68 μm, 5 %)/OA/kerosene shows the best combustion rate of 0.6320 mm2/s. Finally, a numerical model for the combustion of Mg-based nanofluid fuel droplets is proposed. The predictions are within 2 % of the experimental results. The findings are expected to explore future in-situ utilization of CO2 on the Mars surface.

Effects of urban financial agglomeration on managerial mobility and corporate management compensation

Considering the geographical and economic characteristics of corporations, this article examines the impact of financial agglomeration on managerial compensation level and structure in A-share listed corporations from 2008 – 2022. Results demonstrate a direct relationship between urban financial agglomeration and managerial remuneration. Furthermore, the remuneration structure of these managers includes a significant proportion of equity incentives. This conclusion remains significant after conducting robustness tests to ensure reliability and validity. Additional research suggests that management migration is a small-scale mechanism through which urban financial agglomeration boosts managerial compensation and the proportion of equity incentives.

The optimization of mechanical properties of polypropylene/styrene butadiene rubber/silicon carbide nanocomposites using response surface methodology

AbstractPolypropylene is a useful and widely consumed thermoplastic with very good properties that can be mixed with a combination of rubber and nanoparticles in order to eliminate its shortcomings. In this paper, the simultaneous combination of both the toughening effect of styrene–butadiene rubber (SBR) and the reinforcing effect of silicon carbide (SiC) nanoparticles were investigated in polypropylene matrix. Mechanical properties (tensile and impact strength [TS and IS]) of compounds were analyzed using the central composite design approach in Design‐Expert software. With two factors for input variables of SBR and SiC weight percentages, and their five levels (5, 10, 15, 20, and 25) and (0, 1.5, 3, 4.5, and 6), respectively, the central composite design approach employs 11 experiments for creation of models and the analysis of variance investigations with two output responses of TS and IS. Statistical results revealed that SBR and SiC contents had a significant effect on TS, IS, and the microstructure of compounds, as confirmed by scanning electron microscopy and energy‐dispersive spectroscopy images. To maximize all mechanical properties simultaneously with desirability functions, TS and IS of the optimum sample were computed to be 21.98 MPa and 8.66 kJ/m2 in amounts of 13.45 and 2.80 weight percentage (wt%) of SBR and SiC, respectively.Highlights By increasing silicon carbide (SiC) in polypropylene/styrene–butadiene rubber (SBR), tensile strength decreases after a peak due to agglomeration effect. By increasing SiC in polypropylene/SBR, impact strength decreases after a peak due to agglomeration effect. By increasing SiC, the rubber particles' dimensions decrease according to scanning electron microscopy analysis. Simultaneous maximum of tensile strength and impact strength are 21.98 MPa and 8.66 KJ/m2, respectively. Optimum value of SBR and SiC in above maximums are 13.45 and 2.8 wt%, respectively.

Assessing the social risks of flooding for coastal societies: a case study for Prince Edward Island, Canada

With the worldwide growing threat of flooding, assessing flood risks for human societies and the associated social vulnerability has become a necessary but challenging task. Earlier research indicates that islands usually face heightened flood risks due to higher population density, isolation, and oceanic activities, while there is an existing lack of experience in assessing the island-focused flood risk under complex interactions between geography and socioeconomics. In this context, our study employs high-resolution flood hazard data and the principal component analysis (PCA) method to comprehensively assess the social risk of flood exposure and social vulnerability in Prince Edward Island (PEI), Canada, where limited research has been delivered on flood risk assessments. The findings reveal that exposed populations are closely related to the distribution of flood areas, with increasingly severe impact from current to future climate conditions, especially on the island’s north shore. Exposed buildings exhibit a concentrated distribution at different levels of community centers, with climate change projected to significantly worsen building exposure compared to population, possibly due to the urban agglomeration effect. The most populated cities and towns show the highest social vulnerabilities in PEI, and the results reflect a relatively less complex economic structure of islands. Recommendations for research and management in the coming stage include the necessity of particular climate actions, recognizing community centers as critical sites for flood hazard responses, and incorporating flood hazards into urban planning and management to mitigate the impacts of continuous urbanization on ecosystem services for flood prevention.

Assessing the spatiotemporal evolution and socioeconomic determinants of PM2.5-related premature deaths in China from 2000 to 2021

China's swift socioeconomic development has led to extremely severe ambient PM2.5 levels, the associated negative health outcomes of which include premature death. However, a comprehensive explanation of the socioeconomic mechanism contributing to PM2.5-related premature deaths has not yet to be fully elucidated through long-term spatial panel data. Here, we employed a global exposure mortality model (GEMM) and the system generalized method of moments (Sys-GMM) to examine the primary determinants contributing to premature deaths in Chinese provinces from 2000 to 2021. We found that in the research period, premature deaths in China increased by 46 %, reaching 1.87 million, a figure that decreased somewhat after the COVID-19 outbreak. 62 thousand premature deaths were avoided in 2020 and 2021 compared to 2019, primarily due to the decline in PM2.5 concentrations. Premature deaths have increased across all provinces, particularly in North China, and a discernible spatial agglomeration effect was observed, highlighting effects on nearby provinces. The findings also underscored the significance of determinants such as urbanization, import and export trade, and energy consumption in exacerbating premature deaths, while energy intensity exerted a mitigating influence. Importantly, a U-shaped relationship between premature deaths and economic development was unveiled for the first time, implying the need for vigilance regarding potential health impact deterioration and the implementation of countermeasures as the per capita GDP increases in China. Our findings deserve attention from policymakers as they shed fresh insights into atmospheric control and Health China action.

Experiments and kinetic modeling of the sorbitol dehydration to isosorbide catalyzed by sulfuric acid under conditions of non-constant volume

Isosorbide is a novel bio-based material, derived as a secondary dehydration product of sorbitol. This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of non-constant volume. Herein, the effects of stirring rate, catalyst dosage, reaction temperature, and reaction time on the dehydration reaction of sorbitol were investigated. The yield of isosorbide up to 77.13% was obtained after 1.5 hours of reaction time under conditions of 2 kPa, 1.0% (mass) catalyst dosage, and 413.15 K. Based on the sorbitol dehydration reaction mechanism and a simplified reaction network, a kinetic model was developed in this work. A good agreement was accomplished between kinetic modeling and experiments between 393.15 and 423.15 K. The fitting results indicate that side reactions with higher activation energy are more affected by reaction temperatures, and the main side reaction that influences the selectivity of isosorbide is the oligomerization reaction among the primary dehydration products of sorbitol. The model fitting of the catalyst amounts effect shows that the effective concentration of sulfuric acid would be reduced with the increase of dosage due to the molecular agglomeration effect. Hopefully, the kinetic experiments and modeling results obtained in this work will be helpful to the design and optimization of the industrial sorbitol dehydration process.

Predicting effective elastic modulus of CNT metal matrix nanocomposites: A developed micromechanical model with agglomeration and interphase effects

Agglomeration and interphase region of fillers are two important factors that affect the mechanical properties of metal matrix composites reinforced with carbon nanotubes (CNT-CMMs). However, most of the existing theoretical models predict an ascending linear in strength for composites with increasing filler content, which disagrees with the experimental results, especially at high filler loading. In fact, at high CNT concentrations, agglomeration and weak interphase region bonding reduce the strength and consequently degrade the mechanical properties of composites. Based on the mean-field theory, we present a novel micromechanical model to predict the elastic modulus of CNT-CMMs by considering the effects of these two factors. Furthermore, we investigate the effect of other parameters such as CNTs aspect ratio, agglomeration amount, interphase layer thickness and modulus, and matrix modulus on the elastic modulus of CNT-CMMs. Finally, we validate our model by comparing it with numerous experimental outcomes from the literature signifies good precision. Using this model, it is possible to optimize the filler value and also maximize the elastic modulus, which can be a powerful tool for designing the CNT-CMMs.

Land Green Utilization Efficiency and Its Driving Mechanisms in the Zhengzhou Metropolitan Area

Improving land green use efficiency is of great significance for promoting high-quality economic development and promoting the modernization of harmonious coexistence between humans and nature. In this study, the super-efficiency SBM model with non-expected output was used to measure the level of land green use efficiency at county scale in the Zhengzhou metropolitan area from 2005 to 2020. Based on this, the spatio-temporal evolution and spatial agglomeration characteristics were analyzed. Finally, the driving mechanisms were revealed by using the geographical detector model. The results were as follows: (1) From 2005 to 2020, the land green use efficiency of the Zhengzhou metropolitan area fluctuated from 0.5329 to 0.5164, with an average annual decline rate of 0.21%, exhibiting three stages: decline, rise, then another slight decline. At the city level, Luohe City had the highest land green use efficiency, while Zhengzhou City had the lowest. (2) The land green use efficiency of the Zhengzhou metropolitan area showed a significant spatial positive correlation, Moran’s I index increased from 0.1472 to 0.2991, and the spatial agglomeration effect was continuously enhanced. On the local scale, high-high (H-H) aggregation and low-low (L-L) aggregation were dominant, high-high (H-H) aggregation areas were mainly distributed in the southwest and southeast of the Zhengzhou metropolitan area, and low-low (L-L) aggregation areas were mainly distributed in the central and western parts of the Zhengzhou metropolitan area. (3) There is heterogeneity in the degree of influence of different driving factors on land green use efficiency in the Zhengzhou metropolitan area, which is ranked as topographic relief (X7) > forest coverage rate (X8) > social consumption (X6) > industrial structure (X3) > urbanization rate (X2) > economic development (X1) > industrial added value scale (X5) > financial expenditure (X4). q values were 0.1856, 0.1119, 0.1082, 0.0741, 0.0673, 0.0589, 0.0492 and 0.0430, respectively. The interaction of two factors can enhance the explanatory power of land green use efficiency in the Zhengzhou metropolitan area. Except for the interaction of topographic relief and forest coverage rate, the other factors all show double factor enhancement. The explanatory power of the interaction between topographic relief and urbanization rate is the strongest, at 0.3513. In the future, policy regulation should be carried out from the perspectives of the interaction of social and economic conditions such as improving forest coverage rate, improving consumption power, optimizing industrial structure and improving land green use mechanisms to promote the improvement of land green use efficiency.

The Economic Spillover Effect of the Collaborative Agglomeration between Manufacturing and Producer Services

High-quality economic development is an inevitable requirement for promoting sustainable development. Stacks of research papers have suggested that the quality of China’s economic development will make an important contribution to promoting global sustainable development. The collaborative agglomeration between manufacturing and producer services is determined by multiple factors, including industrial characteristics and industrial associations. This is conducive to the efficient evolution of the industrial structure and to further achieving high-quality economic development. Based on the provincial data from 2010 to 2021 in China, this research evaluated the impact of co-agglomeration between manufacturing and producer services on high-quality economic development by using the double-fixed-effect spatial Durbin model. The benchmark regression results showed that industrial co-agglomeration impacted high-quality economic development in an inverted U-shaped. This result had a significant positive spatial spillover and was robust. In the spatial heterogeneity tests, the co-agglomeration of industries had different effects on high-quality development in regions. The strongest spillover effect of positive externalities was in the eastern region, which played an active role as a “growth pole”. The “siphon effect” happened in the central region. The spillover effect had a “U” shape in the western region, and the co-agglomeration inhibited current high-quality development. In the mechanism analysis, the industrial co-agglomeration enhanced high-quality development by stimulating green innovation, and the digital economy had a positive moderating effect. The study presented in this article provides empirical evidence and offers policy recommendations for formulating industrial policies and improving the quality of economic development.

Nano-modified recycled aggregates via vacuum impregnation: Towards stronger and durable recycled concrete

For the first time, this study aimed to enhance the quality of recycled aggregates (RAs) by employing nano-silica (NS) and the vacuum impregnation technique. Specifically, RAs experienced water immersion, ordinary and vacuum impregnation with 2 % NS slurry, and vacuum impregnation with 4 % NS slurry. Subsequently, these nano-modified RAs were incorporated into concrete mixes, and their strength and durability were assessed. Following this, an examination of the pore structures and properties of the interfacial transitional zones (ITZs) in recycled concrete was conducted. The results demonstrate that in contrast to ordinary pretreatment methods, concrete containing nano-modified recycled aggregates after vacuum impregnation exhibits better compressive strength (+18.39 %) and reduced chloride ion penetration (−17.90 %), which is attributable to a more compact pore structure and enhanced ITZs. The findings prove that vacuum impregnation significantly enhances the modification impact of NS on RAs when compared to conventional impregnation methods, owing to the reduced agglomeration effect of NS in concrete.

Research on the Impact of Financial Agglomeration on Green Investment

With growing global attention on sustainable environmental development, green investment has become an important tool to drive the green transformation of the economy. Financial agglomeration areas, as capital-intensive regions, provide strong support for green technological innovation and eco-environmental projects. Additionally, the policy inclinations and investment preferences of financial agglomeration areas directly influence the flow and efficiency of green funds, further shaping the path of economic green transformation. Based on this, this paper selects panel data from 31 provinces in China (except Hong Kong, Macau, and Taiwan) over 15 years from 2007 to 2021. Using the fixed effects model, the study examines the impact of financial agglomeration on the scale of green investment and conducts a heterogeneous analysis of the effects in different regions of China, as well as proposing related policy suggestions. The results show that an increase in the level of financial agglomeration can significantly enhance the scale of green investment in a region, especially in the central regions. Compared to the eastern and western regions, the promotion effect of financial agglomeration is more pronounced in the central region.

Flow Behavior of Nanoparticle Agglomerates in a Fluidized Bed Simulated with Porous-Structure-Based Drag Laws.

Fluidization bed reactor is an attractive method to synthesize and process quantities of functional nanoparticles, due to the large gas-solid contact area and its potential scalability. Nanoparticles fluidize not individually but as a form of porous agglomerates with a typical porosity above 90%. The porous structure has a significant effect on the hydrodynamic behavior of a single nanoparticle agglomerate, but its influence on the flow behavior of nanoparticle agglomerates in a fluidized bed is currently unclear. In the present study, a drag model was developed to consider the porous structure effects of nanoparticle agglomerates by incorporating porous-structure-based drag laws in the Eulerian-Eulerian two-fluid model. Numerical simulations were performed from particulate to bubbling fluidization state to evaluate the applicability of porous-structure-based drag laws. Results obtained for the minimum fluidization and bubbling velocities, bed expansion ratio, and agglomerate dispersion coefficient show that, compared with the drag law of solid sphere, the porous-structure-based drag laws, especially the drag law of fractal porous spheres, provide a closer fit to the experimental data. This indicates that the pore structures have a great impact on gas-solid flow behavior of nanoparticle agglomerates, and the porous-structure-based drag laws are more suitable for describing flows in nanoparticle agglomerate fluidized beds.

Research on enhanced mass transfer using audible acoustic agglomeration technology

Currently, tail flues of coal-fired power plants are treated using wet desulfurization process to remove pollutants. But, the treated flue gas has a significant moisture loss and this process also contributes to environmental pollution. Acoustic agglomeration is a non-contact treatment process that can effectively solve the problem of moisture loss in flue gas; however, there are few theoretical and experimental studies on acoustic droplet agglomeration applied to coal-fired power generation. In this paper, an experimental platform for acoustic droplet agglomeration is demonstrated to recover moisture. Further, the effects of important factors such as acoustic frequency, sound pressure level and droplet flow rate on the agglomeration efficiency are investigated. The experimental results show that there are two optimal frequencies exist, namely 500 Hz and 1200 Hz, for the droplets used in this experiment with acoustic droplet agglomeration. A highest efficiency of 58% is achieved at 500 Hz. The acoustic action differs between the 500 Hz and 1200 Hz cases. The analysis suggests that the primary force driving droplet agglomeration at 500 Hz is likely the acoustic flow effect. On the other hand, the main mechanism behind acoustic agglomeration at 1200 Hz could be related to the acoustic wake effect. Sound pressure level is the primary factor affecting droplet agglomeration, and the agglomeration efficiency increases with sound pressure, reaching 96.7% at 150 dB. Furthermore, the agglomeration effect shows a positive correlation with droplet flow rate, while the agglomerated particle size also increases simultaneously. This research provides a new idea for moisture recovery, which could offer valuable insights for implementing acoustic droplet agglomeration and moisture recovery in power plants.

Flotation behavior and mechanism of microfine apatite and illite in different electrolyte solution systems

The deep sea is rich in mineral resources, and due to the scarcity of freshwater resources, the use of seawater is becoming more widespread. However, the presence of a large number of electrolyte ions in seawater can pose a challenge to mineral flotation and the effects of different electrolytes vary. This study investigated the effects of common chloride (Cl-) electrolyte solutions of Na+, Mg2+ and Ca2+ on the flotation behavior of microfine apatite and illite using sodium oleate (NaOL) as the collector and acidified sodium silicate (ASS) as the depressant. The results showed that ASS can selectively adsorb to the surface of illite as Si(OH)4, hindering the action of NaOL but having little effect on apatite. The electrolyte solution improved the foaming performance of the slurry. It also reduced the critical micelle concentration (CMC) of NaOL and promoted the formation of NaOL micelle, which promoted the adsorption of NaOL on the surface of apatite. However, the reaction of free Mg2+ and Ca2+ in the slurry with oleic anion consumed the effective components of the collector, which was not conducive to mineral flotation. After NaOL interacted with apatite, it had hydrophobic agglomeration effect, which strengthened the flotation recovery of microfine apatite and the separation efficiency from illite.

Can market-oriented and government-led spatial agglomeration of factories reduce carbon emission intensity? Evidence from China

Both market-oriented and government-led spatial agglomeration of factories profoundly affect China's carbon emission intensity. However, few studies have comprehensively examined the effect of spatial agglomeration of factories driven by different motivations on carbon emission intensity, and often ignore the moderating effect of local government attention to the environment. This study attempts to incorporate market-oriented and government-led spatial agglomeration of factories into the same analytical framework and examine their interaction effects on carbon emission intensity. We first calculate an Agglomeration Index based on the geographic coordinates of micro-factories to measure market-oriented agglomeration of factories, and take development zone policies as a proxy for government-led agglomeration of factories. Based on city-level data from 1998 to 2013, we empirically analyze their impacts on carbon emission intensity and further explore regional heterogeneity and mechanisms. The results show that both the market-oriented and government-led spatial agglomeration of factories can significantly reduce carbon emission intensity through scale effect, innovation effect and structure effect. However, the agglomeration of factories caused by government forces has weakened the original effect of market-oriented agglomeration of factories in reducing carbon emission intensity. Heterogeneity analysis indicates that government-led agglomeration of factories is more effective in reducing carbon emission intensity in less-developed regions. Furthermore, the improvement of the governments' attention to the environment can further exert the positive effect of spatial agglomeration of factories on carbon emission intensity. Our study deepens the understanding of the effects of spatial agglomeration of factories caused by different motivations, and provides a reference for China and other developing countries to formulate relevant policies for reducing carbon emission intensity.

Intelligence and carbon emissions: The impact of smart infrastructure on carbon emission intensity in cities of China

Urban infrastructures are facing environmental degradation induced by surging energy demand. There is an urgent need for countries to create a greener and more efficient infrastructure. Smart infrastructure (SI), as a new type of digitally enhanced infrastructure, has a strong potential to reduce carbon emissions. This study examines the nexus between smart infrastructure and carbon emission intensity (CI) in China, encompassing 251 cities from 2011 to 2019. The findings indicate that: (1) Every 1 % improvement in smart infrastructure reduces carbon emission intensity by 0.2810 %. This effect is significant only in more advantageous geographic locations and non-resource-dependent cities. (2) Panel threshold regression analysis demonstrates a nonlinear relationship between smart infrastructure and carbon intensity, showing a decreasing trend followed by an increasing trend under different energy consumption levels. (3) Mechanism analyses show that smart infrastructure affects carbon intensity through technological innovation and agglomeration effects. (4) Smart infrastructure exerts spatial spillover effects on carbon intensity with substantial spatial decay effects. This paper deepens the understanding of smart infrastructures and provides an empirical basis for the deployment of smart infrastructures to achieve carbon neutrality.

How Can Low-Carbon City Construction Enhance Urban Economic Resilience? A Mechanism Analysis Based on Industrial Agglomeration and Technological Innovation Effects

How Can Low-Carbon City Construction Enhance Urban Economic Resilience? A Mechanism Analysis Based on Industrial Agglomeration and Technological Innovation Effects

Is there an agglomeration economy in Eastern Russia?

ABSTRACT This analysis has disproved the widespread opinion that, in Eastern Russia, where the settlement structure and transport network are less dense, agglomeration effects are either absent or negligible. Econometric estimates have revealed a significant contribution of agglomeration economies to the efficiency of companies mainly in the southern regions. However, for a substantial part of Eastern Russia, agglomeration effects are insignificant and for some territories they are negative. The manifestation of agglomeration effects depends neither on the density of economic activity nor on the development of communication infrastructure. Lack of cooperation between local producers hinders the realisation of existing agglomeration potential in Eastern Russia.