Search Results (901)

This study assessed the techno-economic performance and energy efficiency of scrap tyre valorization through pyrolysis in Nigeria, comparing two configurations: a pyrolysis plant integrated with power generation (Scenario 1) and a standalone pyrolysis plant (Scenario 2). Process simulations were carried out using Aspen Plus V12, and cost estimations were performed with the Aspen Process Economic Analyzer. For a feed capacity of 20 tons per hour, the pyrolysis process yielded steel wire (15.04%), char (35.57%), pyro-diesel (37.94%), gas (7.91%), and heavy oil (3.54%). Scenario 2 achieved a higher energy efficiency (94.44%) than Scenario 1 (51.23%). However, Scenario 1 demonstrated superior economic performance, with a Net Present Value (NPV) of USD 28.65 million and an Internal Rate of Return (IRR) of 34.48%, despite its higher capital investment of USD 27.63 million. Sensitivity analysis revealed that the selling price of pyro-diesel and the cost of scrap tyres were the most influential parameters affecting profitability. The findings provide useful insights for optimizing scrap tyre pyrolysis systems toward sustainable waste-to-energy applications in developing regions. Full article

In response to the requirements for groundwater pollution risk identification and zoning-based management in typical coastal industrial agglomeration areas, this study takes the coastal industrial zone of the Jidong Plain as the research area and. It develops an integrated evaluation framework for groundwater pollution prevention zoning. The framework is quantitatively centered on pollution source load assessment and groundwater vulnerability analysis, and applies the Analytic Hierarchy Process (AHP) solely as an interpretative and decision-support tool. In this study, the Linear Weighted Function (LWF) method and the DRASTIC model are employed to quantitatively characterize pollution source load intensity (PI) and groundwater system vulnerability (DI), respectively. By constructing a prevention and control index (R) in the form of the product of pollution source load and groundwater vulnerability, the framework achieves an integrated representation of pollution input intensity and the carrying capacity of the groundwater system. The AHP is not directly involved in indicator weighting or zoning calculations; instead, it is applied as a post hoc analytical approach to identify the relative importance of different evaluation factors in groundwater pollution prevention zoning, thereby supporting the interpretation of the zoning results and management priority setting. The results indicate that the overall pollution source load in the study area is relatively low, with low-to-moderately low load zones accounting for 68.7% of the area. In comparison, high-load zones account for only 1.43% and are mainly concentrated in the southeastern coastal industrial belt. Shallow groundwater generally exhibits high vulnerability, with highly vulnerable zones covering 86.56% of the area and predominantly distributed in the northeastern Quaternary unconsolidated sedimentary regions. Based on the prevention and control index (R), the study area is classified into prevention zones and remediation zones. Prevention zones account for 94.47% of the total area, whereas remediation zones account for 5.53%. High-risk areas are mainly concentrated in coastal industrial belts and highly vulnerable cultivated areas. The results demonstrate that the proposed integrated evaluation framework effectively couples pollution source load and groundwater vulnerability, and, on the basis of the finalized zoning results, enhances the interpretability and management specificity of the zoning outcomes through post hoc decision-support analysis, thereby providing a scientific basis and methodological reference for groundwater pollution prevention zoning and differentiated management in coastal industrial regions. Full article

High-speed rotating machinery often demands bearings with superior load capacity and thermal stability. Here, a four-chamber radial hydrodynamic sliding bearing using supercritical carbon dioxide (S-CO₂) as a lubricant is investigated to address these requirements. The work is carried out on the ANSYS Workbench 2024 R1 platform. Computational fluid dynamics (CFD) and structural mechanics are combined to build a fluid–structure interaction (FSI) numerical model. The model accounts for real-gas thermophysical property variations. S-CO₂ properties are dynamically retrieved using the REFPROP database and MATLAB curve fitting. Unlike previous studies that mainly focused on hydrostatic structures and general parameters, this research examines hydrodynamic lubrication behavior under ultra-high-speed conditions. It systematically analyzes the effects of rotational speed on oil film pressure distribution, load capacity, friction coefficient, and housing deformation. It also investigates cavitation characteristics in a specific speed range. Simulation outcomes reveal that higher rotational speeds lead to an increase in both oil film load capacity and peak pressure. In particular, when the speed rises from 4000 r/min to 12,000 r/min, the maximum positive pressure increases from about 10 MPa to approximately 10.4 MPa. Meanwhile, the negative pressure region becomes significantly larger, which raises the cavitation risk and indicates a less stable lubrication state at very high speeds. These results confirm that lubrication simulations incorporating real-gas effects can reliably represent the operating behavior and provide useful guidance. It also provides new theoretical support for the design optimization and engineering application of S-CO₂-lubricated bearings in high-speed machinery. Full article

Against the backdrop of the deepening aging population in rural China and the impetus of government policies, it is necessary for social work to intervene in rural elderly care services. However, issues related to a lack of resources and sustainability exist both in the methods of intervention by social work organizations and in the operation of rural elderly care service sites. Based on a case study and in-depth interviews conducted at a social work-operated elderly care service center in Village N, Guangxi Zhuang Autonomous Region, this study analyzes how social workers can achieve sustained intervention in rural elderly care services and how to promote the sustainability of these services. The findings indicate that through the approach of rural integration, social workers embed themselves into the rural field across three dimensions: organizational structure, local culture, and practical action. In this process of integration, they construct the legitimacy for social workers to carry out services, stimulate the vitality of internal rural resources, enhance the capacity of internal rural resource stakeholders, and simultaneously attract and connect external resource stakeholders to supply resources for rural elderly care services, thereby effectively achieving the integration of internal and external resources. The study concludes that the approach of rural integration enables social workers to rapidly gain legitimacy and facilitates the subsequent delivery of services. Building upon this, effective resource integration can sustain the outcomes of rural elderly care service provision, compensate for resource deficiencies, and enhance the sustainability of rural elderly care services. Full article

The district heating system (DHS) can provide flexibility to the electrical power system (EPS) in the coordinated dispatch of an integrated power and heat system (IPHS). To exploit the energy storage capacity of the DHS and support the flexible IPHS operation, it is essential to characterize the flexible operation region (FOR) of the DHS. This paper proposes an FOR characterization method for the DHS, based on a Farkas-cut outer approximation algorithm (FCOAA). The FOR characterization is formulated as a polyhedral projection problem. Within the FCOAA-based framework, the feasible cut generation model is constructed as a bilinear programming problem, which is relaxed by using the normalized multiparametric disaggregation technique (NMDT) and converted into a mixed-integer linear programming (MILP) problem. Numerical simulations on a 6-bus/6-node IPHS are carried out to validate the proposed method, and key factors influencing the flexibility of the DHS are analyzed. Full article

Seismic performance evaluation of existing buildings is essential for defining effective mitigation strategies in earthquake-prone regions. This study investigates the seismic performance of low-rise unreinforced masonry (URM) residential buildings located in several cities in the Albanian territory. Material properties were obtained from experimental tests conducted on representative samples and subsequently adopted in the development of analytical models. Three-dimensional finite element models were generated based on the collected geometric data and experimentally determined material characteristics. Nonlinear static (pushover) analyses were carried out to assess the seismic capacity and identify the potential failure mechanisms of the buildings. The numerical results showed significant variation in performance depending on the building typology, with some cases reaching the near-collapse limit state under design-level earthquakes. The capacity curves and performance points obtained from the models demonstrate the pronounced influence of construction techniques, boundary conditions, and material properties on the seismic response. The results indicated that URM residential buildings exhibit distinctive seismic performance characteristics influenced by their construction techniques and material properties. Based on the findings, recommendations for retrofit strategies are proposed to enhance the seismic resilience of such structures. Full article

Grasslands represent an essential resource for rural economies and for the provision of ecosystem services, yet they are increasingly affected by anthropogenic pressures, functional land-use changes, and institutional constraints. This study develops a geospatial decision-support framework for assessing grassland suitability in Hunedoara County, Romania, by integrating the Analytic Hierarchy Process (AHP) and Weighted Overlay Analysis (WOA) within a GIS environment. The assessment is based on nine criteria thematically grouped into three dimensions: (A) physical-geographical, including topographic suitability, climatic pressure, and hydrological risk exposure; (B) ecological and conservation-related, reflected by ecological conservation value, ecological carrying capacity, and the anthropic pressure index; and (C) socio-economic and functional, represented by spatial accessibility, recreational value, and policy support mechanisms. Suitability is defined as the integrated capacity of grasslands to sustain productive and multifunctional uses compatible with ecological conservation and the existing policy framework. Results indicate that 0.43% of the grassland area exhibits very high suitability (Class 1), 44.51% high suitability (Class 2), and 54.75% moderate suitability (Class 3), while unfavorable areas account for only 0.31% of the total (Class 4). The proposed methodology is reproducible and transferable, providing support for prioritizing management interventions, agri-environmental payments, and rural planning in mountainous and hilly regions. Full article

This study aims to examine the methodological applicability of the Theory of Inventive Problem Solving (TRIZ) in the conservation and revitalization of traditional military settlements. Using Zhenjing Village in Jingbian County as a case, the research constructs a systematic framework for contradiction identification and strategy generation. Methods: Through preliminary surveys, data integration, and system modeling, the study identifies major conflicts among authenticity preservation, ecological carrying capacity, and community vitality in Zhenjing Village. Technical contradiction matrices, separation principles, and the Algorithm of Inventive Problem Solving (ARIZ) are employed for structured analysis. Further, system dynamics modeling is used to simulate the effectiveness of strategies and to evaluate the dynamic impacts of various conservation interventions on authenticity maintenance, ecological stress, and community vitality. The research identifies three categories of core technical contradictions and translates the 39 engineering parameters into an indicator system adapted to the cultural heritage conservation context. ARIZ is used to derive the Ideal Final Result (IFR) for Zhenjing Village, which includes self-maintaining authenticity, self-regulating ecology, and self-activating community development, forming a systematic strategy. System dynamics simulations indicate that, compared with “inertial development,” TRIZ-oriented strategies reduce the decline in heritage authenticity by approximately 40%, keep ecological pressure indices below threshold levels, and significantly enhance the sustainability of community vitality. TRIZ enables a shift in the conservation of traditional military settlements from experience-driven approaches toward systematic problem solving. It strengthens conflict-identification capacity and improves the logical rigor of strategy generation, providing a structured and scalable innovative method for heritage conservation in arid and ecologically fragile regions in northern China and similar contexts worldwide. Full article

The study presents a stability analysis of an axially compressed column resting on a Winkler foundation with a stepwise variation in stiffness. The solution is based on an energy approach using the Rayleigh quotient, and the original buckling mode function is proposed to capture the localization of deformations in the region of foundation discontinuity. The theoretical model was verified numerically for rectangular-section columns by comparing the results with simulations performed in COSMOS/M and ABAQUS systems. The differences in critical load values did not exceed 1.7%. The investigation showed that increasing the stiffness contrast leads to stronger buckling localization within the weaker foundation segment. The developed model can be used for preliminary assessment of the load-carrying capacity of structural elements interacting with a non-homogeneous distributed foundation. Full article

To investigate the spatiotemporal evolution of ecosystem health in a typical rocky desertification control demonstration zone. This study utilized land use data and remote sensing imagery from 1992, 2003, 2009, 2015, and 2021. Landscape pattern analysis was employed to quantify landscape characteristics. A Pressure-State-Response (PSR) model framework was integrated to establish an ecosystem health assessment system comprising 14 indicator factors, enabling ecosystem health evaluation from the perspective of coupling landscape patterns and ecological processes. Key findings reveal: Significant cropland expansion occurred within the study area, accompanied by mutual transitions within ecological land types, yet the overall landscape structure remained relatively stable. The regional landscape underwent substantial transformations, characterized by grassland reduction alongside increases in cropland and shrubland. These changes led to decreased landscape heterogeneity and fragmentation, an increasingly dominant landscape matrix, significantly enhanced connectivity, and reduced diversity. Ecosystem health experienced an initial deterioration phase followed by gradual recovery. By 2021, a transition trend emerged where a suboptimal state prevailed, yet localized areas exhibited improved quality. Distinct variations in ecological response mechanisms were observed across different geomorphic types. Unhealthy ecosystems were predominantly distributed in areas of intensive human activity, specifically peak-cluster platforms (I), eroded platforms (III), and V-shaped valleys (V). These results underscore the necessity of considering differential ecological carrying capacities inherent to various geomorphic types during rocky desertification control. Implementing differentiated management strategies and adaptive governance is crucial for promoting the sustainable enhancement of regional ecosystem health. Full article

Al–Al₄C₃ composites exhibit promising mechanical properties including high specific strength, high specific stiffness. However, high reinforcement contents often promote brittle behavior, making it necessary to understand the mechanisms governing their limited toughness. In this work, a microstructural and mechanical study was carried out to evaluate the energy storage capacity in Al–Al₄C₃ composites fabricated by mechanical milling followed by heat treatment using X-ray diffraction (XRD) and Convolutional Multiple Whole Profile (CMWP) fitting method, the microstructural parameters governing the initial stored energy after fabrication were determined: dislocation density (ρ), dislocation character (q), and effective outer cut-off radius (R_e). Compression tests were carried out to quantify the elastic energy stored during loading (Es). The energy absorption efficiency (EAE) in the elastic region of the stress–strain curve was evaluated with respect to the elastic energy density per unit volume stored (Ee), obtained from microstructural parameters (ρ, q, and Re) present in the samples after fabrication and determined by XRD. A predictive model is proposed that expresses Es as a function of Ee and q, where the parameter q is critical for achieving quantitative agreement between both energy states. In general, samples with high EAE exhibited microstructures dominated by screw-character dislocations. High-resolution transmission electron microscopy (HRTEM) analyses revealed graphite regions near Al₄C₃ nanorods—formed during prolonged sintering—which, together with the thermal mismatch between Al and graphite during cooling, promote the formation of screw dislocations, their dissociation into extended partials, and the development of stacking faults. These mechanisms enhance the redistribution of stored energy and contribute to improved toughness of the composite. Full article

Against the backdrop of national policies promoting coordinated regional development and ecological civilization construction, the contradiction between ecological security and environmental carrying capacity in the Yangtze River Delta urban agglomeration has become increasingly prominent. However, the interaction mechanisms between these two systems remain insufficiently explored. This study constructs a comprehensive evaluation indicator system for ecological security and environmental carrying capacity in the Yangtze River Delta. A double exponential function is employed to examine the intensity of interaction pressure and reveal their nonlinear relationship. The coupling coordination model is applied to assess coordinated development trends, while a vector autoregression (VAR) model is used to identify the dynamic response relationships among system variables. The results indicate that the overall levels of both systems have improved, with core areas maintaining a leading position and southeastern, northeastern, and western regions remaining in a catching-up stage, accompanied by low-level convergence. Regional coordination exhibits a positive temporal evolution from imbalance to coordination, while its spatial pattern evolves from core dominance toward multi-regional convergence. Significant regional heterogeneity is observed in shock responses, with peripheral cities facing stronger industrial restructuring pressures showing greater ecological volatility. Overall, the dynamic interaction between ecological security and environmental carrying capacity demonstrates a stage-specific transition from mutual constraint to mutual promotion. This study provides empirical support for ecological restoration and regional sustainable development policymaking. Full article

Background and Objectives: Type 2 diabetes mellitus (T2DM) is increasing in prevalence worldwide, placing a substantial burden on healthcare systems, particularly in resource-limited settings. In Yemen, limited screening and diagnostic capacity contribute to delayed detection and management. Prediabetes, a reversible state of dysglycemia, carries significant cardiovascular risk and frequently progresses to diabetes. Early identification of both conditions is vital for prevention and public health planning. Materials and Methods: This cross-sectional study, conducted from July 2024 to May 2025 in three medical centers in Ibb Governorate, Yemen, assessed 1045 adults aged 18–60 years without known diabetes or prediabetes. Glycaemic status was classified according to the 2025 American Diabetes Association criteria. Undiagnosed diabetes was defined using three diagnostic combinations: FBS + OGTT, FBS + HbA1c, and OGTT + HbA1c. Results: The prevalence of undiagnosed diabetes was 8.4% (FBS + OGTT) and 9.76% (FBS + HbA1c or OGTT + HbA1c). Prediabetes prevalence was 23.4%, 14.7% and 26.4% based on FBS, OGTT, and HbA1c, respectively. Females represented a higher proportion of undiagnosed diabetes and prediabetes cases. Age was significantly associated with glycemic status across all tests, while gender showed significant associations with FBS and HbA1c. Family history of chronic disease was significantly associated with HbA1c-based classification. Approximately 8–10% of adults in Ibb had undiagnosed diabetes, while up to one-quarter had prediabetes. Age and family history were key predictors of dysglycaemia. Conclusions: These findings highlight the need for targeted, multi-marker screening and early intervention strategies, particularly in relatively stable regions of conflict-affected settings, to prevent progression to diabetes and reduce long-term complications and healthcare burden. Full article

This study addressed the issue of insufficient lubrication in the thrust washer of the planetary gear reducer during operation. Numerical simulations were performed under fixed operating conditions, combined with sequential optimization strategy, to systematically investigate the influence of V-shaped texture distribution and geometric parameters on lubrication characteristics during unidirectional rotation. The results revealed that, under the examined texture parameters, the oil film pressure increased significantly with increasing radial velocity from inner to outer radius and lubricant viscosity, with area density being the key parameter influencing load-carrying capacity. Moreover, selectively enhancing the texture density in the outer ring region effectively alleviated wear caused by stress concentration in that area. The optimal V-shaped texture parameters were determined as follows: a length ratio of 5, an angle of 30°, an area density of 24.52%, and a depth of 0.02 mm. The symmetry axis of the texture was oriented opposite to the fluid velocity, and the texture distribution exhibited radial densification. This study will inform the design of surface textures and enhance the lubrication performance of mechanical components in thrust washers and similar rotational operating conditions. Full article

Openings are often introduced in continuous reinforced concrete (RC) deep beams to accommodate utility services, which can compromise their structural capacity. This paper presents a numerical investigation—via nonlinear finite element (FE) modeling—into the effects of post-construction rectangular openings in continuous high-strength concrete (HSC) deep beams. A previously tested two-span continuous HSC deep beam with rectangular openings was used for model validation and subsequently adopted in a parametric study, maintaining consistent beam and opening dimensions. The study focuses on the influence of opening location, both symmetric and asymmetric, at mid-depth within critical shear and flexural zones of the two-span continuous deep beam. Key parameters analyzed include load-carrying capacity, support reactions, initial and post-cracking stiffness, reinforcement stresses, and concrete stress distribution. Results indicate that mid-depth openings located in flexure-critical regions have minimal impact, causing only a 3–5% reduction in load-carrying capacity and negligible changes in stress behavior. However, when openings intersect the primary strut paths, reductions in capacity ranged from 17% to 53%, depending on the number and location of the openings (i.e., crossing external or internal struts). Furthermore, symmetric placement of openings was found to significantly mitigate performance degradation compared to asymmetric configurations. These findings provide design insights that enable safe incorporation of service openings without excessive material use, thereby promoting more sustainable and resource-efficient concrete construction. Full article