Search Results (117)

This paper examines the operational consequences and energy demands associated with the growing cultural diversity of air travellers at airport security checkpoints. The analysis focuses on how an increasing proportion of passengers requiring enhanced security screening, due to cultural, religious, or linguistic factors, affects both system throughput and energy consumption. The methodology integrates synchronised measurement of passenger flow with real-time monitoring of electricity usage. Four operational scenarios, representing incremental shares (0–15%) of passengers subject to extended screening, were modelled. The findings indicate that a 15% increase in this passenger group leads to a statistically significant rise in average power consumption per device (3.5%), a total energy usage increase exceeding 4%, and an extension of average service time by 0.6%—the cumulative effect results in a substantial annual contribution to the airport’s carbon footprint. The results also reveal a higher frequency and intensity of power consumption peaks, emphasising the need for advanced infrastructure management. The study emphasises the significance of predictive analytics, dynamic resource allocation, and the implementation of energy-efficient technologies. Furthermore, systematic intercultural competency training is recommended for security staff. These insights provide a scientific basis for optimising airport security operations amid increasing passenger heterogeneity. Full article

This study aims to develop and apply an improved flow–consumption statistics (FCS) method to more accurately assess food and grain self-sufficiency in China. By incorporating dynamic food loss and waste estimates, the FCS method enhances accuracy and spatial resolution. Results from 2010 to 2022 show a national decline in food self-sufficiency to 82%, while grain self-sufficiency remains above 90%. Nineteen provinces failed to achieve food self-sufficiency, with notable regional disparities. Northern inland areas outperform southern coastal regions, which rely more on inter-regional transfers. The average national food loss and waste rate reached 22.8%. The FCS method provides a robust tool for policymakers to evaluate food security risks amid shifting socio-economic and environmental conditions. Full article

Thus far, various aquaculture modes have been developed to facilitate the rapid growth of the aquaculture industry and thus meet the heavy demand for aquatic products for human consumption. However, the effects of different culture modes on fish muscular nutritional content and volatile flavor are rarely reported. In the present study, we evaluated the differences in muscular nutrition content and dietary flavor between Chinese longsnout catfish (Leiocassis longirostris) groups cultured in two different modes, i.e., flow-through water tanks (CWWL) and traditional ponds (CWWC). Our statistical results showed that a significantly higher crude protein content and lower crude fat levels were observed in the CWWL group than in the CWWC group (p < 0.05). Similarly, the contents of total aromatic amino acids (Total ∑TAA) and total dicarboxylic amino acids (Total ∑DAA) were also significantly higher in the CWWL group. Among the fatty acids, long-chain polyunsaturated fatty acids (LC-PUFAs), including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (ARA), were recorded at 1.44%, 2.5%, and 9.09%, respectively, in the CWWL group, which were dramatically higher than in the CWWC group. Conversely, the contents of volatile compounds, including 2-tridecanone, dimethyl trisulfide, and isophorone, in the CWWC group were also significant higher, which, however, may contribute to an unpleasant sensory experience. Conversely, other compounds like 2-methylbutanal and 2,3-butanedione were prevalent in the CWWL group, which can induce rich nutty and buttery flavors and thus enhance the freshness of flavor profiles. In conclusion, Chinese longsnout catfish cultured in flow-through tanks show higher nutritional value and better sensory flavor in comparison with those raised in ponds. These findings not only provide novel insights into the potential effects of aquaculture modes on muscular nutrition content and dietary flavor for Chinese longsnout catfish but also lay a solid foundation for optimizing practical culture modes to improve the global aquaculture industry. Full article

The transesterification process for biodiesel production is constrained by high thermal input, prolonged residence time, and intensive mechanical agitation. This study investigates process intensification via hydrodynamic cavitation using a custom-built Shockwave Power Reactor (SPR), enabling continuous biodiesel synthesis from soybean and used cooking oils. A statistically designed experimental matrix was applied to evaluate the reactor’s transient–stable thermal regime and the influence of operational parameters: rotor speed (1700–3415 rpm), volumetric flow rate (60–105 mL/min), methanol-to-oil molar ratio (6:1 to 12:1), and alkali catalyst type (NaOH or KOH). For benchmarking, conventional alkaline transesterification was optimized. The FAME yields from the SPR system exceeded 96.5% and complied with EN14103 standards. Specific energy analysis showed that cavitation-enhanced transesterification reduced energy consumption and peak temperature compared to traditional methods. The SPR’s capacity to induce high shear and localized turbulence under controlled cavitation offers a promising pathway for low-energy, scalable biodiesel production. Full article

The increasing adoption of electric vehicles (EVs) has highlighted the need for sustainable lithium-ion battery (LIB) management. This study presents a material flow analysis (MFA) of EV LIBs in the Republic of Korea (RoK), using both a mass-based MFA and a substance flow analysis (SFA). The analysis defines 33 systems and 170 flows across the manufacturing, consumption, discharge and collection, and treatment stages, based on national statistics and data from 11 commercial facilities. In 2022, about 72,446 t of EV LIBs entered the consumption stage through new vehicle sales and battery replacements. However, domestic recovery was limited, as approximately 76.5% of used EVs were exported, reducing the volume of batteries available for recycling. The SFA, focusing on nickel (Ni), cobalt (Co), manganese (Mn), and lithium (Li), showed recovery rates of 69% for Ni, 80% for Co, 1% for Mn, and 80% for Li. Mn was not recovered because its low market price made the recovery process economically impractical. Additional losses occurred from the incineration of separators containing black mass and lithium discharged through wastewater. These findings offer data-driven insights to improve recovery efficiency, guide policy, and enhance the circularity of EV LIB management in the RoK. Full article

Concrete demolition waste represents a critical bottleneck in achieving a circular economy for the construction sector. This study develops a system-dynamics model that couples material flows with economic and logistical feedback to quantify how cost structures affect concrete recycling in the Sydney (Australia) metropolitan area. The model is calibrated with (i) official New South Wales 2020–2021 construction-and-demolition waste statistics, (ii) concrete consumption data scaled from state infrastructure reports, and (iii) parameters elicited from structured interviews with recycling contractors and plant operators. Scenario analysis systematically varies recycling-plant fees, landfill levies, and transport costs to trace their nonlinear impacts on three core performance metrics: recycling rate, cumulative landfill mass, and virgin gravel extraction. Results reveal distinct cost tipping points: a 10% rise in landfill-logistics costs or a 25% drop in recycling logistics costs shifts more than 95% of concrete waste into the recycling stream, cutting landfill volumes by up to 47% and reducing virgin aggregate demand by 5%. Conversely, easing landfill costs by 25% reverses these gains, driving landfill dependency above 99% and increasing gravel extraction by 39%. These findings demonstrate that carefully calibrated economic levers can override logistical inefficiencies and accelerate circular construction outcomes. The system-dynamics framework offers policymakers and industry stakeholders a decision-support tool for setting landfill levies, recycling subsidies, and infrastructure investments that jointly minimize waste and conserve natural resources. Full article

The COVID-19 pandemic has led to significant shifts in global water consumption, particularly affecting wastewater treatment plants (WWTPs). In Kuwait, where high residential water usage exists, the lockdowns resulting from the pandemic created a unique opportunity to evaluate the effects of altered human activity on wastewater characteristics. This study examines the effects of the lockdown on key wastewater parameters, including flow rate, COD, BOD, TSS, total Kjeldahl nitrogen (TKN), and total phosphorus (TP). Data were collected from four WWTPs in Kuwait over 4 to 8 years, with the Kabd WWTP providing continuous daily data for an 8-year period. A comparative analysis was conducted between pre-lockdown, lockdown, and post-lockdown periods using statistical methods such as paired t-tests. The study also integrates a global comparison to relate Kuwait’s findings. Results indicate a significant increase in wastewater flow (7.6%) during the lockdown, rising from 165,486 m³/d to 178,033 m³/d. COD and BOD levels increased by 27.1% and 18.9%, respectively, while TSS showed the largest rise at 29.9%. TKN increased by 20.1%, indicating higher nitrogenous waste contributions from residential sources. These findings highlight the pandemic’s impact on wastewater characteristics in Kuwait, driven primarily by increased domestic water consumption. The study underscores the necessity of adaptive wastewater management strategies, especially in semi-arid regions, where WWTPs must be equipped to handle unexpected changes in wastewater composition. This research provides essential insights for improving the flexibility of wastewater systems with future disruptions, contributing to both environmental management and public health awareness. Full article

In this study, inexpensive, environmentally friendly, and biodegradable cellulose filter paper was used to load nano zero-valent iron (nZVI), effectively improving the dispersibility of nZVI and successfully preparing the supported modified cellulose filter paper (FP-nZVI). Subsequently, the capacity of FP-nZVI to remove Cr(VI) in a flow system was explored. FP-nZVI was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Traditional single-factor experiments often require a large number of repeated experiments when analyzing the interactions among multiple variables, resulting in a long experimental cycle and high consumption of experimental materials. This research used the Response Surface Methodology (RSM) based on the Box-Behnken Design (BBD) and the Artificial Neural Network (ANN) to optimize and predict the removal process of Cr(VI). This RSM investigated the interactions between the response variable (Cr(VI) removal rate) and the independent variables (Cr(VI) concentration, pH value, and flow rate). A highly significant quadratic regression model was constructed, which was proven by a high F value (93.92), an extremely low p-value (<0.0001), and a high determination coefficient (R² = 0.9918). An ANN model was established to forecast the correlation between independent variables and the removal rate of Cr(VI). Both models demonstrate remarkable consistency with the experimental data; however, from the perspective of statistical parameters, the ANN model has more significant advantages; the coefficient of determination R² reaches 0.9937, which is higher than that of RSM (0.9918); the values of indicators such as MSE, RMSE, MAE, MAPE, AAD, and SEP are all smaller than those of RSM. The ANN exhibits greater excellence in prediction error, value fluctuation, and closeness to the actual value and has a more excellent prediction ability. The experiment for treating Cr(VI) with FP-nZVI was optimized, achieving good results. Meanwhile, it also provides a valuable reference for similar experimental studies. Full article

Regional planning agencies increasingly rely on Spatial Economic Models (SEMs) to evaluate the impact of various policies. However, traditional SEMs often employ homogeneous technical coefficients (TCs) to represent technology patterns used by activities located in very different areas of a region, leading to misrepresentations of production and consumption behaviors, and consequently, inaccurate modeling results. To this end, we propose a Differential Spatial Economic Modeling (DSEM) framework that incorporates region-specific TCs for activities within Independent Planning Units (IPUs), such as provinces or cities, each characterized by unique economic, demographic, and technological features. The DSEM framework comprises three core components: (1) a regional economy model that forecasts activity totals for each IPU using economic and demographic forecasting model, supplemented by statistical analyses like the Gini index and K-means clustering to group activities from different IPUs into homogeneous ‘technology’ clusters based on their TCs; (2) a land use model that allocates IPU activity totals to corresponding traffic analysis zones (e.g., counties or districts) using the Differential Spatial Activity Allocation (DSAA) method. This determines the spatial distribution of commodities (such as goods, services, floor space, and labor) across exchange zones, balancing supply and demand to achieve spatial equilibrium in both quantity and price; and (3) a transport model that performs modal split and network assignment, distributing commodity trip origin–destination matrices across a multimodal transportation supernetwork (highways, railways, and waterways) using a probit-based stochastic user equilibrium assignment model. The proposed method is applied to a case study of the Yangtze River Economic Belt, China. The results demonstrate that the proposed DSEM yields better goodness-of-fit (R²) values between observed and estimated flows compared to the traditional aggregate SEM. This indicates a more precise and objective representation of spatial economic activities and technological patterns, thus resulting in improved estimates of freight flows for individual transportation modes and specific links. Full article

Background/Objectives: Femoral head avascular necrosis (FAN) is a serious orthopedic disorder that causes the death of bone tissue as the outcome of the occlusion or insufficiency of the vessels supplying blood to the femoral head. It is especially common in middle-aged men. Factors such as alcohol consumption, corticosteroid use, trauma, and systemic diseases have influential roles in the development of FAN, and the ensuing vascular disruptions can also negatively affect the patient’s broader systemic vascular health. Erectile dysfunction (ED) is a condition caused by an impairment in penile blood flow, which reduces quality of life in men and has psychosocial effects. This study examined the potential relationship between FAN and ED in consideration of the similar pathophysiological mechanisms of these conditions. Methods: The research was planned as a retrospective case–control study and conducted between January 2020 and December 2023. FAN was diagnosed based on the Ficat–Arlet classification using plain radiography and magnetic resonance imaging, and staging was performed with expert clinical evaluations. The International Index of Erectile Function (IIEF) scale was administered to evaluate ED. Data from 50 patients with FAN and 50 healthy men were evaluated using appropriate statistical methods, including univariate comparisons and correlation analysis. Results: The analysis demonstrated a significant association between increasing FAN stages and greater severity of erectile dysfunction (ED). ED was identified in 35 out of 50 patients in the FAN group (70%), compared to 15 out of 50 individuals in the control group (30%). This difference was statistically significant (p < 0.05), indicating a substantially higher prevalence of ED in patients with FAN. A significant negative correlation was also observed between the FAN stage and International Index of Erectile Function (IIEF) scores (Spearman’s rho = −0.631; p = 0.001). The mean IIEF score was 23.4 in patients with FAN stage 1, which declined to 9.6 in those with stage 4, reflecting a marked deterioration in erectile function with advancing FAN stages. No statistically significant difference was found in the age distribution between the FAN and control groups (p > 0.05). Conclusions: This study demonstrates that, with the progression of FAN, systemic vascular deterioration affects penile blood flow, increasing the severity of ED. This finding highlights the common pathophysiological mechanisms of FAN and ED and reveals the importance of early diagnosis and multidisciplinary treatment approaches. This relationship should be examined in detail with larger samples and prospective designs in future studies. Full article

In dredging operations, the efficient transportation of dredged materials presents a significant and intricate challenge. This study focuses on the motion and resistance characteristics of coarse-grained dredged materials during pipeline conveyance. A specialized simulation experiment platform was developed to investigate the horizontal pipeline transport of coarse-grained materials. The experimental design encompassed varying particle diameters, material volume concentrations, and mixed average flow rates to analyze the motion and resistance characteristics of these materials in horizontal pipelines. Three distinct particle beds were identified based on different coarse particle motion states. This study statistically analyzed the impact of the particle diameter and material volume concentration on the transport efficiency of coarse particle populations. The key findings indicate that the mixed mean flow rate significantly influences the transportation efficiency of coarse particle groups, whereas the particle diameter and material volume concentration have a minimal effect. Specifically, coarse particles with a diameter of 0.9 mm demonstrated optimal water flow following, and higher mixed mean flow rates correlated with increased transportation efficiency of the coarse particle group. The transition speed of the coarse particle group flow type was notably affected by the material volume concentration and particle diameter, exhibiting a linear relationship. Therefore, when the particle size of the dredged material increases or the concentration increases, the average flow rate of the mixture is appropriately increased to ensure that the flow pattern of the dredged material in the pipeline remains in a non-homogeneous suspended flow pattern, thereby improving the efficiency and stability of the transportation system. By optimizing the conveying characteristics of coarse-grained materials, the pipeline conveying efficiency can be improved and the risk of pipeline wear and clogging can be reduced, thus lowering engineering costs and energy consumption and promoting technological innovation in related industries. In addition, this research can enhance engineering safety, reduce resource waste and environmental pollution, promote sustainable development, and provide important theoretical support and practical guidance for emerging fields such as deep-sea mining and environmental engineering. Full article

Secondhand clothing has undergone a significant transformation from a vital household asset in the pre-industrial era to a dynamic segment of global trade in the 21st century. However, the advent of fast fashion has led to overproduction and mass consumption of inexpensive garments, fueling a surge in the secondhand clothing trade. Between 2002 and 2022, the market value of this industry quadrupled, with exports accounting for 1.17% of total global clothing exports in 2022. This study examines global secondhand clothing exports using export competitiveness tools such as revealed comparative advantage (RCA), the index of export market penetration (IEMP), the trade intensity index (TII), unit values, market shares, and the compound annual growth rate (CAGR). The top eleven secondhand clothing exporting countries are analyzed for a ten year period (2013 to 2022) using the United Nations Commodity Trade Statistics Database. The analysis reveals notable trends: the United States and China dominate the market, while Pakistan and the UAE exhibit the highest growth rates. The study also reaffirmed that trade patterns for secondhand clothing continue to flow from the Global North—including China—to the Global South, a trend observed since the early 2000s. This research provides a comprehensive, current analysis of the ever growing secondhand clothing export market within the sustainable management of the secondhand clothing context. Full article

As a clean energy source, shale gas plays a crucial role in mitigating the supply–demand imbalance of natural gas and in facilitating the transition to a low-carbon economy. This study employs a system dynamics model to forecast future production trends in shale gas in China, analyze its implications for the natural gas supply–demand structure, and explore pathways for sustainable development. Firstly, by integrating the characteristics of China’s shale gas resources, market dynamics, and policy frameworks, the key factors influencing production are identified, and their interrelationships are systematically analyzed. Subsequently, a causal loop diagram is constructed using the VENSIM software(VENSIM PLE 9.3.5 x64), a set of representative variables is selected, and the logical relationships among these variables are established through a multivariate statistical analysis, culminating in the development of a production forecasting model for China’s shale gas (stock and flow diagram). Finally, based on parameter assumptions, this study predicts the production trends in shale gas in China under multiple scenarios. The forecasting results reveal that China’s shale gas production is expected to grow at an average annual rate of 3.32% to 8.02%, with production under the reference scenario projected to reach 724.22 × 10⁸ m³ by 2040. However, the growth of shale gas production over the next two decades remains limited, accounting for a maximum of 12.07% of the total natural gas consumption, underscoring its transitional role in the low-carbon transformation. To address these challenges, this study proposes four policy recommendations: (1) prioritize the development of shallow, high-quality gas-bearing blocks while gradually transitioning to deeper formations; (2) intensify technological innovation in deep shale gas extraction to enhance recovery rates and mitigate production decline rates; (3) implement flexible production subsidies and moderately increase natural gas sales prices to incentivize production and optimize resource allocation; and (4) strengthen ecological conservation and improve water resource management to ensure the sustainable development of shale gas. Full article

The membrane-aerated biofilm reactor (MABR) is an emerging technology for the biological treatment of wastewaters. It can achieve simultaneous nitrification and denitrification due to anoxic liquid conditions. The counter diffusion of oxygen and nutrients in the biofilm allows for aerobic and anoxic layers, providing conditions where the formation, accumulation and consumption of nitrous oxide can all occur. The microbial processes involved in the production and consumption of N₂O are complex, and, due to the innovative nature of the MABR, understanding the influence of operational factors helps to minimise N₂O emission. Using a lab-scale 20L MABR system, an investigation was carried out to determine the influence of operational factors on the emission of nitrous oxide from the reactor. A direct link between the nitrous oxide emissions and bulk liquid conditions could not be established with only limited statistical correlation between them. It was found that under both steady loading rates and transient conditions, the emission of nitrous oxide was most influenced by the air flow rate through the membranes. The majority of N₂O emissions occurred via the membrane off-gas and not through the liquid. N₂O flux through the membrane was influenced not only by the accumulation of N₂O in the biofilm side but also by the gas residence time on the lumen side. Therefore, minimising the air flow rate is an effective strategy to mitigate nitrous oxide emissions from the MABR. Full article

Background: Chronic obstructive pulmonary disease (COPD) is a frequent but underdiagnosed disease, primarily due to the lack of access to forced spirometry (FS) in primary care. Portable, easy-to-use expiratory flow meters like Piko-6^® and COPD-6^® that measure FEV₁, FEV₆, and FEV₁/FEV₆ ratio provide an alternative. Given that Piko-6^® and COPD-6^® devices measure FEV₆ but not FVC, the aim of the study is to determine the optimal cutoff value for the FEV₁/FEV₆ ratio of each device to avoid false negatives when these devices are used for COPD screening in primary care (PC). Methods: A total of 664 patients of 35 years of age or older with a cumulative tobacco consumption of 10 or more packs/year were recruited at two university hospitals. FS (gold standard) was performed and FEV₁, FVC, and FEV₁/FVC measurements were compared with FEV₁, FEV₆, and FEV₁/FEV₆ measurements acquired using Piko-6^® and COPD-6^® devices. The devices were compared using statistical methods including Pearson correlation coefficients, the Youden index (YI), kappa coefficient, Bland–Altman plots, and ROC curves analysis. Results: Correlations between FEV₁/FEV₆ using Piko-6^® and COPD-6^® and FEV₁/FVC with FS were 0.79 and 0.73, respectively. Piko-6^® achieved the best YI in FEV₁/FEV₆ (0.73), whereas for COPD-6^®, it was 0.80. Concordance between Piko-6^® and FS was 83.9% (kappa 0.67 ± 0.028) and for COPD-6^®, it was 68.7% (kappa 0.42 ± 0.02). Conclusions: This is the first study that compares two hand-held expiratory flow meters with FS. Piko-6^® and COPD-6^® devices are effective tools for COPD detection, as their measurements provide a good correlation with FS. In order to avoid false negative results, the FEV₁/FEV₆ cutoff point needs to be increased to 0.73 and 0.80 with Piko-6^® and COPD-6^®, respectively. Full article