Environmental Resource Conservation Research Articles

Development of intelligent waste sorting system of low-value recyclable waste in Xiamen

The classification and recycling of waste are significant for environmental protection and resource conservation. In China, the fine sorting of low-value recyclable waste (LVRW) primarily uses manual sorting, which is inefficient and harmful to health. Automated sorting uses sensors to identify the type of waste on a conveyor belt, which is then automatically separated by a sorting organisation to improve the recycling process. A low-cost, high-performance sorting system was built in this paper. The system used a low-resolution industrial camera to capture colour images of waste and a pneumatic separator to sort the waste. The recognition accuracy of waste was improved by optimising the recognition model and using the copy–paste data augmentation method. Mark pneumatic valve control algorithm is proposed that achieves more than 99% waste recovery even under dense working conditions. The sorting system is suitable for sorting plants and has been applied to a case study of LVRW in Xiamen city. In the sorting experiments under complex working conditions, the purity and recycling rate of plastic and Tetra Pak wastes achieved over 95%. The experiment demonstrates the great potential of the system for waste recycling and will help solve the problem of municipal waste in developing countries.

Magnetization roasting combined with multi-stage extraction for selective recovery of lithium from spent lithium-ion batteries

Lithium-ion batteries recycling is crucial for environmental protection and resource conservation. Among the battery components, lithium holds high value, but current recovery methods exhibit limited efficiency in selectively extracting lithium from spent electrode materials. In this study, we propose a novel pathway that combines magnetization roasting with multi-stage extraction to enhance the recovery of lithium from spent electrode materials. The process begins with the decomposition of the spent ternary cathode material into CoO, NiO, MnO, Co, and Ni at 600 ℃ for 30 min using pyrolysis product-derived reducing agents. Heat-induced magnetization of the cathode plates facilitates magnetic separation, effectively isolating cathode, and anode plates. The cathode material can be recycled by water impact crushing combined with sieving, and 40.80 % lithium dissolves into water for recycling. The comprehensive recycling efficiency of lithium is up to 95.30 % after carbothermal reduction with 15 % carbon addition. The sub-microlevel migration behavior of lithium ions in the proposed scheme was also examined for further mechanistic insights.

Integrated Consideration of Data Flows and Life Cycle Assessment in Vehicle Dismantling processes

The pursuit of environmental sustainability and resource conservation has underscored the growing significance of the circular economy paradigm across industries. This transformation is particularly pertinent within the automotive industry, necessitating a profound restructuring of the value chain, with a specific focus on end-of-life considerations. Significant potential for circular economy arises from the thorough examination of end-of-life vehicles and processes, involving strategies such as component reuse, material recycling and primary resource reduction. Providing process-, product-, component-, and material-specific information at the end-of-life of automotive vehicles can improve decision-making regarding circular strategies. It also demands for new digital solutions. This paper addresses an integrated approach of data flow analysis and Life Cycle Assessment (LCA) to enable a comprehensive monitoring of the environmental impact of these processes. First, the use case of end-of-life dismantling processes is presented - including pyrotechnics neutralization, vehicle dehydration, disassembly of reuse components as well as vehicle compaction. Secondly, the data demand respective information and material flows is depicted. As a main result, the LCA data flow model specifically tailored to the end-of-life vehicle dismantling processes is described. This model serves as a fundamental basis for analyzing the environmental impact of end-of-life processes combined with the underlying data flow.

IMPROVED SORPTION OF PRASEODYMIUM IONS FROM NITRATE SOLUTIONS BY ACTIVATED ION EXCHANGERS

In this research, we investigated the praseodymium ions sorption by the ion exchangers KU-2-8 (H+form) and AV-17-8 (OH-form) as an interpolymer system called "KU-2-8:AV-17-8" (X:Y) with the molar ratio of ionic groups X:Y (6:0, 5:1, 4:2, 3:3, 2:4, 1:5, and 0:6) in praseodymium nitrate solution. To be clear, two cross-linked polymers having active functional groups that are in the same solution but not in direct contact form an interpolymer system. The purposeof our research to demonstrate how activating ion exchangers as functional polymers by remote contact in an aqueous medium enhances the sorption of a variety of valuable metals and their compounds from industrial waste solutions, including praseodymium. Objects.Ion exchangers that are mutually activated in an aqueous medium undergo conformational and electrochemical changes that lead to a shift in their state from neutral to highly ionized and an increase in their sorption activity toward target metal ions. Results.The experimental findings showed that the sorption activity of the interpolymer system KU-2-8:AV-17-8 (5:1) increased significantly when compared to praseodymium ions (43 %), but the sorption activity of the raw KU-2-8 (6:0) and raw AV-17-8 (0:6) had the same values of 25 % and 5 %, respectively. Conclusion. This research sheds light on a novel and promising approach to improve the efficiency of ion exchangers, opening possibilities for the effective recovery and removal of valuable metals from complex solutions. Additionally, it holds practical implications for sustainable waste management and resource recycling, contributing to the advancement of environmental protection and resource conservation in various industrial sectors. Further investigations and optimization of the interpolymer system could yield substantial benefits for greener and more resource-efficient future sorption technologies.

Robust optimization of multi-objective multi-cycle remanufacturing supply chain network considering incentive compatibility theory under improved algorithm

In recent years, industrial production and transportation have generated a significant amount of carbon emissions, leading to a heightened focus on environmental resource conservation. Concurrently, with the development of internet technologies, an increasing number of enterprises are leveraging big data and artificial intelligence for production and logistics. Within this context, the challenge of how enterprises can utilize big data services to reduce costs while minimizing carbon emissions has become a pressing concern. Meanwhile, remanufacturing, as a sustainable solution, has garnered substantial attention. However, remanufacturing supply chain networks become exceptionally complex and challenging when faced with uncertainties in demand and recovery quantities, necessitating government intervention. Thus, to examine the impact of government intervention on the optimization of green remanufacturing supply chain networks, this paper, based on incentive compatibility theory, establishes an optimization function with objectives of minimizing total cost, reducing carbon emissions, and maximizing return on data investment in scenarios marked by uncertain market demand and recovery quantities. It constructs multi-objective fuzzy optimization models for various scenarios. The paper employs improved robust optimization to address uncertainties related to demand and recovery quantities. It also utilizes the Improved Multi-Objective Genetic Algorithm (IMOGA) to address multi-objective optimization, addressing the limitations of Genetic Algorithms (GA) and Multi-Community particle swarm optimization (MPSO). Case study results indicate that robust optimization effectively handles uncertainties in the model, aligning better with real-world conditions. High-tech enterprises often prioritize economic objectives, and government intervention measures can compensate for their limited carbon reduction capabilities. In most cases, the improved multi-objective genetic algorithm (IMOGA) outperforms MPSO and GA in terms of performance. In the context of the evolving internet landscape, high-tech enterprises should harness big data and artificial intelligence to establish green remanufacturing supply chain networks. Simultaneously, government guidance to reduce carbon emissions is instrumental in enhancing corporate competitiveness and industrial upgrading.

Urban polycentrism and total-factor energy efficiency: An analysis based on the night light data

Improving energy efficiency is crucial for environmental protection and resource conservation. Considerable urban system distribution is vital to realizing high energy efficiency. However, studies on energy efficiency from this spatial perspective remain limited. Using the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) and visible infrared imaging radiometer suite (VIIRS) nighttime light data, we measured urban polycentrism (UPC) and employed improved stochastic frontier analysis (SFA) for total-factor energy efficiency (TEE) measurement. Analyzing panel data from 332 prefecture-level cities across 27 provinces of China, we used the spatial economic and threshold models to calculate UPC's impact on TEE and its threshold conditions. The results revealed UPC's effect on TEE and the control variables (economic development, urbanization rate, and industrial structure). The pattern suggests that only when economic development, urbanization rate, and industrial structure reach a certain (range) level in some zones, does the effect change from one condition (inhibition/promotion) to another (promotion/inhibition). Under certain conditions, a win-win situation between UPC and TEE is achieved. Finally, relevant policy recommendations for energy efficiency improvements based on urbanization are discussed. To the best of our knowledge, this is the first study to systematically investigate the impact of UPC on TEE at the city level.

New Optimization Framework for Improvement Sustainability of Wastewater Treatment Plants

Enhancing the sustainability of wastewater treatment plants (WWTPs) is crucial due to their manifold benefits, which encompass environmental preservation, cost reduction, and resource and energy conservation. The achievement of these advantages relies on the careful choice and implementation of retrofit technologies to upgrade WWTPs. However, this decision-making process is intricate, given the trade-offs between the objectives and the inherent decision uncertainties. To address these complexities, this work presents an innovative weighted multi-objective optimization (MOO) framework tailored for WWTP enhancement amid uncertain conditions. This framework comprises two phases. The first phase involves basic definition and information collection through a case-specific assessment, while the second phase includes model formulation and solver optimization, which serves as a generic tool for the weighted MOO problem. In the model formulation, a combined weighting approach that integrates expert opinions and statistical insights is introduced to assign significance to each objective. The solver optimization employs a projection-based algorithm to identify the optimal technology configuration that achieves a satisfactory and balanced improvement across multiple sustainable objectives. By applying this framework to a case plant for retrofit technology selection, the comprehensive sustainability performance, the targeting of discharged pollution, the operational cost, and the GHG emissions improved by 46.7% to 68.3%.

Environmental strategy for sustainable development: Role of digital transformation in China's natural resource exploitation

In light of the rapid evolution of the electrical and electronic industry, coupled with the surge of digitalization and global energy transitions, the imperative for sustainability within various sectors has been accentuated. Rare Earth (RE) metals, pivotal in diverse primary sectors including engine production, aviation, and shipbuilding, are embedded with sustainability challenges such as waste generation and pollution despite their criticality. This research scrutinizes the influence of environmental strategy on the sustainable development of firms within the rare-earth metal sector, with a spotlight on China's substantial sector. Employing hierarchical regression and component-based structural modeling to navigate through causal complexities, the study explores the interplay between digital transformation and environmental sustainability, and their collective impact on sustainable development. Findings unveil a symbiotic relationship between digital transformation and environmental strategy in steering the sustainable development of firms within China's Rare Earth Metals (REMs) sector. The empirical data underscores the pivotal role of Environmental Strategy (ES) in bridging Digital Transformation (DT) and Sustainable Development (SD). The study advocates for a lucid and succinct environmental strategy, encapsulating a firm's dedication to environmental sustainability, encompassing pivotal facets such as environmental compliance, pollution mitigation, and resource conservation. Furthermore, the ES should prioritize measurable environmental targets, embedding specific objectives to mitigate environmental impacts, including the reduction of energy usage, greenhouse gas emissions, and water consumption.

Design Decision-Making for Construction Waste Minimisation: A Systematic Literature Review

The escalating pace of construction activities has triggered a concerning surge in waste accumulation, underscoring the urgent need for the construction industry to prioritise environmental sustainability and resource conservation. Research indicates that construction waste (CW) from a typical building project can comprise a substantial 30% of the total weight of materials transported to the site. Significantly, one-third of this waste could be avoided through judicious decision-making in the design phase. While waste management during construction has gained substantial attention in the existing literature, the domain of decision-making in the design stage remains relatively unexplored. This study addresses this gap by conducting a systematic literature review (SLR) of 59 articles from 2011 to 2022. The findings emphasise the crucial role of informed decision-making processes in minimising CW during building projects. A conceptual framework emerges from the analysis, highlighting the necessity of establishing a foundation for design decision-making to tackle CW issues effectively. Collaborative networks among stakeholders and an enhanced supply chain, bolstered by robust information sharing, are identified as pivotal factors in improving CW minimisation efforts. Consequently, this study advocates for further research to expand the knowledge base in this vital area, underscoring the imperative for collective efforts in advancing sustainable practices within the construction industry.

Valorization of waste gypsum board as a green adsorbent for efficient fluoride removal in groundwater and wastewater treatment

The escalating generation of construction waste during building reconstruction and remodeling underscores the significance of recycling for environmental preservation and resource conservation. In this context, we propose the valorization of waste gypsum board (WGB), a common construction waste material, as a value-added environmental purification agent. WGB, composed primarily of CaSO4, displays the potential to react with fluoride to form CaF2, making it a promising adsorbent for fluoride removal. Through density functional theory analysis, we determined that WGB possesses mesoporous characteristics, with pore sizes ranging from 1 to 20 nm. While thermal treatment has been effective in enhancing fluoride adsorption on other adsorbents, our investigations revealed that the crystalline structure (CaSO4) of WGB remained unchanged under thermal treatment, limiting its impact on the fluoride adsorption capacity. Nevertheless, WGB exhibited a remarkably high fluoride adsorption capacity (285.90 mg/g), surpassing those of other reported adsorbents. Furthermore, the WGB demonstrated excellent fluoride removal performance, even at higher solution pH levels. In artificial wastewater, a dose of 3.33 g/L WGB achieved a remarkable removal efficiency (> 95%). The applicability of WGB was validated by successful fluoride removal in real wastewater and groundwater, with 94% of fluoride in groundwater removed using 0.33 g/L of WGB and 97% of the fluoride in the wastewater removed with 1.67 g/L WGB. This study opens a promising pathway, demonstrating the potential of WGB as a green adsorbent for the effective treatment of fluorine-contaminated wastewater and groundwater, transcending its traditional role in waste recycling.

한국 중고차의 수출경쟁력에 관한 연구

Purpose - For the sustainable trade of the global society, trade phenomena related to the trade of used commodities were analyzed. Used cars are older than new cars, so they are of lower quality and have a lower market value. This makes them a challenging area of research, as there is a lack of prior research.
 Design/Methodology/Approach - From the perspective of environmental conservation and resource conservation, there is a need for research on the export of used cars as a form of resource recycling. The trade phenomenon was analyzed using K-Stat and UN Comtrade Statics data.
 Findings - Used goods trade does not occur only in developing countries, and it is used frequently in developed countries as well. We find a very strong positive correlation between used car exports and new car exports. According to the Trade Specialization Index, used cars have an absolute export competitiveness advantage, even though new cars have low export competitiveness. This suggests that used cars complement new cars in the export market.
 Research Implications - The present study was challenging to undertake due to the fact that it was conducted in the field of used goods, which made it difficult to obtain prior studies and public data. However, the used car sector, a significant component of Korean automobile exports, has been validated as an export product that is competitive with developed countries.

The mutual influence of land-sea ecological security and its coordinated governance in the Guangdong-Hong Kong-Macao greater bay area

Land-sea coordination (LSC) is the key to deepening ecological governance and ensuring the ecological security in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). From the perspective of the human-land-sea giant system, terrestrial and marine environment, terrestrial and marine resources, terrestrial and marine disasters, as well as human socio-economic driving force, pressures and responses are included in the evaluation system of the ecological security of the terrestrial subsystem and the marine subsystem. Using an instrumental variable quantile model, structural equation model and system dynamics model, this study tested the mutual influence of land-sea ecological security in the GBA, as well as its underlying mechanism. The results are summarized as follows: 1) There is a clear non-linear mutualistic symbiosis relationship between the terrestrial subsystem and marine subsystem, while the marine subsystem is influenced by the terrestrial subsystem more significantly; 2) The increasingly scarce terrestrial resources of the GBA cannot provide strong support for turning the GBA into a world-class bay area; however, marine resources effectively offset the shortage of terrestrial resources, the needs of terrestrial socio-economic development provide a core driving force for the marine economy; 3) Ecological problems in the GBA are rooted in the land; the terrestrial socio-economic pressure has unidirectional negative influence on the marine ecology; the terrestrial environment is significantly inferior to the marine environment, and the negative influence on the fostering of terrestrial resources and marine environment is gradually emerging; 4) Marine ecological pressure is mainly rooted in the pollution discharge from terrestrial socio-economic development, but is scarcely related to marine economic development; 5) Owing to the differences in political systems, legal systems and cultural contexts between Guangdong, Hong Kong and Macao, the effectiveness of land-sea ecological governance is not yet significant. Hence, it is advisable to develop an efficient cross-border coordinated governance system, further deepen the land-sea integrated environmental governance, resource conservation, economic transformation and social response across the GBA, build a high-quality land and marine ecological community in accordance with higher standards.

Natural Dyeing with Madder: Exploring Traditional Techniques and Color Characteristics

Abstract The color red has a significant presence in cultures around the world. The organic dye madder, derived from plants, has been used throughout human civilization and remains an important natural dye. The research reviews five traditional madder dyeing techniques from China, Europe, Turkey, and Japan. The techniques are applied to cotton, linen, silk, and wool fabrics, and their similarities and differences are compared and analyzed. Additionally, the environmental sustainability, resource conservation, and process efficiency of these dyeing techniques are also evaluated in this article. The chromatic value of dyed textile color was tested by means of an American Hunterlab spectrophotometer, the influence of different dyeing techniques on textile color characteristics was analyzed, and the artistic features of textile color were analyzed from the perspective of visual art.

Investigating Response Priorities in Oil Pollution Emergencies in an Unloading and Loading Dock Using McKinsey’s 7s Gap Analysis Method

Background & Aims: The most critical environmental challenge of maritime transport in recent decades has been oil pollution. The present study was carried out to identify and determine the rate and ranking of oil pollution in the unloading and loading dock of Imam Khomeini Port by the Development Approach of the Management Model of Prevention and Response against Pollution in Emergencies in 2020. Materials & Methods: In the present descriptive-applied study, the criteria and sub-criteria influencing in prioritizing responses in oil spill emergencies in the unloading and loading dock of Imam Khomeini Port were identified by the documentary method, prioritized based on the technique for order performance by similarity to ideal solution (TOPSIS) multi-criteria decision-making method, and scored by 10 experts. McKinsey’s 7s gap analysis method was also used to estimate the gap between the current and the ideal situation. Results: Out of 18 oil pollution scenarios, 4 were determined as emergencies. Conservation of environmental resources in case of an accident and determination of responsibility before accidents occur, with mean scores of 4.4 and 4.35, were determined as the most important agendas for planning in emergencies. In the gap analysis process with McKinsey’s method and the output spider web model, 7 components of strategy (1.65), skills (1.75), staff (2.2), management style (2.27), shared methods (2.38), structure (2.54), and system (2.79) were determined as the emergency response plan priorities. Conclusion: The study’s results showed that while several factors can result in oil pollution emergencies in the unloading and loading dock of Imam Khomeini Port, there is no ideal situation for managing these threats based on gap analysis.

The use of treated desert sand in sustainable concrete: A mechanical and microstructure study

Desertification stands as a major global issue, while the scarcity of renewable energy sources continues to be a growing concern. To address these challenges, the use of desert sand as a fine aggregate in sustainable concrete has been explored. Desert sand offers numerous advantages such as environmental protection, cost savings, and energy efficiency. This paper examines the impact of treated desert sand on the mechanical and microstructural properties of sustainable concrete. The results of this study reveal that the highest compressive strength was achieved with a 50% replacement level of treated desert sand. The concrete mixture with 50% desert sand achieved the highest 28-day compressive strength at 61.06 MPa. Conversely, the lowest 28-day compressive strength of 41.73 MPa was observed in the concrete mix containing 100% treated desert sand while the control mix with 0% treated desert sand attained a 28-day compressive strength of 48.7 MPa. As the proportion of treated desert sand increased, the workability of concrete decreased. The slump value, which was initially 130 mm for the control mix, dropped to 80 mm in the concrete mix composed of 100% treated desert sand. However, the flexural and tensile strengths tended to decrease as the amount of desert sand increased, particularly beyond a 25% replacement level. The addition of desert sand improves compactness and reduces pores in the samples, as observed through Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy Analysis (EDS) analysis. The results suggest that desert sand can be effectively treated using different treatment methods and used as a fine aggregate in various applications within the construction industry. This research sheds light on the potential of desert sand in sustainable concrete production, contributing to environmental preservation and resource conservation efforts.

A promising method for the liberation and separation of solar cells from damaged crystalline silicon photovoltaic modules

Reasonable and efficient recycling of waste crystalline silicon (c-Si) photovoltaic (PV) modules benefits environmental protection and resource conservation. The liberation and separation of solar cells in modules is the key to achieving effective recycling. The recovery of intact waste modules has been studied by some scholars, but few have specifically examined damaged modules. This study focused on modules that have been broken during transportation, installation, use, or disassembly. Two liberation methods, mechanical crushing and pyrolysis were compared from the perspectives of particle size distribution and morphological characteristics of products. In addition, for separating glass particles and solar cells of coarse fraction, an environmentally-friendly technology of gas-solid fluidized bed was introduced based on their shape and density difference. The effects of airflow velocity and fluidizing time on separation efficiency were investigated for different size fractions. Results showed that pyrolysis was a more suitable liberationliberation method for damaged modules. Higher liberation efficiency could be obtained by pyrolysis, and over-crushing of glass particles and solar cells could be avoided. The optimum pyrolysis conditions were found to be at 500 °C with a holding time of 30 min. The recovery and concentration of solar cells in the >4 mm size fraction were 91.09% and 84.4%, respectively, under the following conditions: 85 m3/h airflow velocity; 90s fluidizing time. For the 2–4 mm size fraction, the recovery and concentration were 82.29% and 80.52% under airflow velocity of 75 m3/h, fluidizing time of 90s. This research presents an alternative process for recovering damaged c-Si PV modules.

통일과 안보 전략상 비무장지대(DMZ) 제도화에 관한 입법적 검토

The current Yoon Suk Yeol administration has clearly defined North Korea and strengthened cooperation between South Korea, the U.S., and Japan, but there is still room for inter-Korean summits due to peaceful unification and national security strategies. Therefore, in the long run, various strategies are needed to improve inter-Korean relations, and one of the issues that can be suggested is the institutionalization of the Demilitarized Zone (DMZ).
 The Demilitarized Zone should be converted from a military zone to a peace zone, developed into a clean ecological zone, and transformed into an inter-Korean joint cooperation project site that creates high added value. In addition, it is important to consistently convey and gain sympathy with North Korea by excluding any political considerations and using them together only from the perspective of economic and social benefits and environmental protection.
 In order to promote inter-Korean cooperation projects in the Demilitarized Zone, new normative systems such as new agreements and treaties that supplement and update the armistice agreement must be derived. South Korea may also consider forming a multilateral consultative body led by the United Nations, the United Nations Command, North Korea, and interested countries.
 Therefore, there is a fundamental limit to planning and implementing a master plan for the Demilitarized Zone and the border area unless compatible measures between legislation are taken suddenly under the current individual law system. Therefore, it is necessary to prepare an “institutional platform” so that all policies and discussions related to the Demilitarized Zone can be implemented consistently within the legal framework.
 Accordingly, an institutional platform for establishing cooperative projects is established through the enactment of the Special Act on Conservation and Sustainable Utilization of Environmental Resources in Demilitarized Zone. A practical project model is needed.

A Comprehensive Approach to Assess the Impact of Agricultural Production Factors on Selected Ecosystem Services in Poland

The conservation of environmental resources is aimed at ensuring the continuity of ecosystem services for future generations and maintaining ecosystem integrity. Given the extensive reliance of agriculture on the environment, it is crucial to identify factors that impact the quality of ecosystem services (ESs), which can be regulated at large and heterogeneous national or European scales. This research, conducted within the Polish use case of the AGRICORE project, aims to demonstrate the feasibility of establishing indicators depicted in three ES categories, which can be shaped under the actions of the Common Agricultural Policy (CAP). The study was conducted based on national sources, mostly the database of the Central Statistical Office. The analyses of regression showed a significant impact of selected agricultural productivity factors on the key performance indicators (KPIs) assessing the level of selected ESs. The yield of cereal grains, which quantitatively expresses the potential of current crop production, depended to the greatest extent (r = 0.81) on a comprehensive indicator of the agricultural production space suitability, as well as on the rise of the level of nitrogen fertilization (r = 0.68), and also on the reduced share of permanent grassland in the agricultural area (r = −0.53). It was proved that in territorial units, in which the level of nitrogen fertilization per 1 ha was greater, the share of soils with favorable pH > 5.5 was also greater. The gross nitrogen balance had a positive and significant correlation with the level of investment subsidies (r = 0.86), the share of agricultural land in the total area (r = 0.67), and the level of nitrogen fertilization (r = 0.66). Notably, there were positive correlations between the level of environmental subsidies and the increase in forestation (r = 0.68) and also between air quality and the share of cereals in the sowing structure (r = 0.86). Additionally, the impact of agricultural productivity factors on cultural eco-services was found, e.g., the share of ecological land had a positive impact on the number of natural monuments, the area of nature reserves, the number of agritourists, and agritourism nights, while the share of cereals in the sowing structure negatively correlated with the most of analyzed cultural indicators. These results are useful for the development of a module for the ABM model that employs the desired environmental parameters to provide different assessments of the impact of selected agricultural productivity factors and ecosystem services on the economic farm status.

Evolution of the pore structure of pumice aggregate concrete and the effect on compressive strength

Abstract China possesses abundant pumice resources and thereby makes the utilization of pumice in the preparation of pumice aggregate concrete (PAC) a significant strategy for environmental protection and resource conservation. To obtain the effect of pumice pore structure variation on the compressive strength of PAC, PACs with strength classes LC20, LC30, and LC40 were prepared. Moreover, the pore structure of PAC was characterized using nuclear magnetic resonance to investigate the effect of pore structure variation on the compressive strength of PAC. Results showed that the higher the coarse aggregate content of PAC, the higher the percentage of large capillary and non-capillary pore sizes of PAC, corresponding to higher porosity and lower compressive strength. The hydration products in PAC continuously fill in the pore structure, the proportion of large capillary pores and non-capillary pore size gradually decreases, the proportion of small capillary pores and medium capillary pore size gradually increases, the pumice concrete matrix gradually becomes dense, and the compressive strength increases. The prediction model of the pore structure and compressive strength is established based on gray theory, and the relative error between predicted and tested values is not significant, which can effectively predict its compressive strength. It provides effective guidance for the engineering practical application of PAC.

Influence of FDI on China's Green Marine Economy

China attaches great importance to the protection of Marine resources, the development of Marine economy and the construction of a maritime power. FDI is highly concentrated in China's coastal areas and accompanied by space spillover, which affects the development speed and quality of Marine economy. Does FDI improve the efficiency of China's Marine green economy? Based on the panel data of 11 coastal provinces and cities in China from 2004 to 2020, the "efficiency evaluation system of Marine green economy" is constructed from the dual perspective of environmental constraints and resource conservation, considering the unexpected output and measuring the efficiency of Marine green economy with the ultra-efficiency SBM model. Then, under the geographical weight and economic geographical weight, the FDI spatial index is constructed to study its influence on the efficiency of Marine green economy. The results show that FDI space can improve the efficiency of Marine green economy in China. FDI has a negative effect on the efficiency of Marine green economy, but after considering the spatial factors, the FDI spatial index has a positive promotion effect on the improvement of the efficiency value, and the promotion effect is more significant under the weight of economic geography and space.