Search Results (48,417)

As renewable energy sources are integrated into power grids on a large scale, modular multilevel converter-high voltage direct current (MMC-HVDC) systems face two significant challenges: traditional PI (proportional integral) controllers have limited dynamic regulation capabilities due to their fixed parameters, while improved PI controllers encounter implementation difficulties stemming from the complexity of their control strategies. This article proposes a dual-agent adaptive control framework based on the twin delayed deep deterministic policy gradient (TD3) algorithm. This framework facilitates the dynamic adjustment of PI parameters for both voltage and current dual-loop control and capacitor voltage balancing, utilizing a collaboratively optimized agent architecture without reliance on complex control logic or precise mathematical models. Simulation results demonstrate that, compared with fixed-parameter PI controllers, the proposed method significantly reduces DC voltage regulation time while achieving precise dynamic balance control of capacitor voltage and effective suppression of circulating current, thereby notably enhancing system stability and dynamic response characteristics. This approach offers new solutions for dynamic optimization control in MMC-HVDC systems. Full article

Forest cover dynamics are studied on a routine basis, but how changes in forest cover impact forest fragmentation has rarely been studied over a long time period resolution. This is, however, important because forest fragmentation critically impacts ecosystem services, such as biodiversity and cooling effects. Here, we apply a long time series of Landsat images from 1986–2018 and study how forest fragmentation has changed along with forest cover dynamics in southern China. Furthermore, we attribute drivers and study the impact on local air temperature changes. The region is particularly relevant as it was largely deforested three decades ago, and most of the current forests are the result of protection and forestation measures. We found a reduction in the forest fragmentation index FFI (−34.4%) from 1986 to 2018. In 81.2% of the area, forest cover increased and fragmentation decreased, while 18.5% of the area showed increases in both forest cover and fragmentation. The contribution of human activities to forest fragmentation increased by 9%, with a distinct spatial correlation between areas of increasing forest fragmentation and high levels of human disturbance. Furthermore, we found that the average level of cooling effects in areas with increased forest cover of less than 40% is heavily dominated by forest fragmentation, whereas the cooling effects are primarily controlled by changes in forest cover. These findings underscore the role of human disturbance in driving forest fragmentation, which in turn affects the functioning of forest ecosystems. The results emphasize the need for integrated land management strategies that balance forest restoration with the mitigation of human-induced fragmentation to sustain ecosystem services in the face of ongoing environmental change. Full article

The inclusion of people with hearing impairments in logistics environments is a topic of increasing importance, especially when considering the promotion of diversity and accessibility in the workplace. The use of a risk perception questionnaire can represent an effective tool to identify barriers and challenges faced by these workers. The questionnaire covers several aspects, including communication between employees, the adequacy of visual signage, workplace safety and the accessibility of tools and equipment. The responses collected help to understand how people with hearing impairments perceive the risks inherent in their work activities, as well as to identify possible deficiencies in the training and awareness of their coworkers. Analysis of the data collected by the questionnaire allows companies to develop specific strategies and actions to improve inclusion, such as inclusive training, adaptation of the physical environment and implementation of auxiliary technologies. In this way, these actions not only contribute to a safer and more productive work environment, but also value diversity and the unique contribution that each worker can make to the logistics sector. Full article

This study focuses on the importance of the real-time monitoring of bolt loads in roadways affected by high-intensity mining and the limitations of conventional monitoring methods. Fiber Bragg grating (FBG) sensors were embedded and encapsulated in rock bolts, and tensile tests were conducted indoors to verify their feasibility. The research was conducted using the consolidated face of the Bultai Coal Mine in the Shendong Mining Area as the engineering background. Real-time monitoring wavelength data from the FBG bolt sensor were obtained through field tests. The analysis of the data aimed to assess the condition of the FBG sensor and variations in axial force within the service bolts of the mining roadway. Using these monitoring results, the real-time stability and safety of the roadway bolts were evaluated. The study indicates that as the working face advances, the axial force in the bolt progressively rises under the effect of mine pressure. The left gang bolt rod’s shaft force changes significantly, while the right gang’s change is relatively small. When the working face moves 60 m past the bolt rod, the axial force in the bolt rises sharply. Moreover, the axial force at different positions of the left and right gang bolts exhibits a distinct variation pattern. The real-time monitoring of bolt support in the return roadway provides essential data for assessing bolt safety. Full article

With the increasing demand for mineral resources, sustainable mining development faces challenges such as low resource utilization efficiency. Ore blending optimization has emerged as a critical approach to enhance resource utilization. This study constructs a multi-objective ore blending optimization system for complex polymetallic open-pit mines based on the improved matter-element extension model and NSGA-II algorithm. By identifying key blending factors, objective functions are established to minimize both total ore quantity deviation and grade deviation, with six constraints defined to reflect production capacity limits. The NSGA-II algorithm is employed to solve the multi-objective optimization problem, generating a Pareto optimal solution set from which the optimal ore blending scheme is selected using the improved matter-element extension model. A case verification at Dabaoshan Mine demonstrates that the model-verified scheme achieves 1.035% higher total production accuracy than the planned value and 2.828% higher than actual production, while improving Cu grade deviation accuracy by 7.021% over the plan and 1.064% over actual production, and S grade deviation accuracy by 33.027% over the plan and 3.127% over actual production. This study, through the construction of systematic ore blending theory and empirical analysis, provides an important theoretical framework and methodological support for subsequent research on ore blending in polymetallic open-pit mines. It demonstrates significant practical application value in Dabaoshan Mine, offering an intelligent mine solution that combines scientific rationality and engineering practicability for polymetallic open-pit mines. Full article

Background: Phenylketonuria (PKU) is a rare metabolic disorder requiring lifelong dietary treatment. Adolescents and young adults face unique challenges in managing the condition, often compromising adherence and psychological well-being. This study aimed to explore coping strategies used by patients to manage their condition and their associations with dietary adherence, PKU-related symptoms, and quality of life (QoL) in young individuals with PKU. Methods: A cross-sectional study was conducted with 21 adolescents and young adults (13–25 years) with classical PKU, followed at the Unit of Inherited Metabolic Diseases in Padua, Italy. Participants completed questionnaires assessing dietary adherence, QoL, and coping. Biochemical data were collected from medical records. Results: Only 57.1% fully adhered to the diet; social barriers like embarrassment and school/work environments hindered adherence. Adolescents reported more irritability and concentration difficulties, while young adults reported greater fatigue. QoL was moderately impacted. Avoidance coping was more frequent in young adults and correlated with irritability and lower QoL. Transcendence-oriented coping was linked to fewer insomnia symptoms. Conclusions: Coping strategies influence symptom experience and QoL in PKU. Integrating psychological support and personalized care into routine treatment is essential to improve adherence and support patients through the transition to adulthood. Full article

In African patriarchal contexts, women have borne the dual responsibilities of mental and physical caregiving for their households and communities. These responsibilities often contribute to significant emotional, social, and economic burdens imposed by deeply entrenched gender and power structures. Alternative psychological coping mechanisms emerge to navigate these challenges, some deeply rooted in cultural and historical practices. One such practice is soil eating, which has been observed in various African communities. Historically linked to cultural and spiritual beliefs, soil eating has been largely unexplored from a psychological perspective. This paper examined soil eating as a coping strategy among women in Africa, investigating its role as a means of emotional relief, resistance, or a symbolic reclamation of agency in the face of oppression. Drawing on the indigenous knowledge systems (IKS) of eZiko siPheka siSophula as a psychological framework, this study engaged sixteen women aged 20 to 89 in Ha Makintane Lesotho to participate in focus group discussions and reveal their personal narratives, cultural traditions, and the intersections of gender, race, and class to understand how this practice helps them manage their mental and emotional toll of patriarchal dominance. This research contributes to discussions on resilience, survival, and the psychological strategies developed by marginalized communities, shedding light on the complex interplay between cultural practices, mental health, and gendered experiences of power. Full article

An urban heat island (UHI) refers to urban areas that experience higher temperatures due to heat absorption and retention by impervious surfaces compared to the surrounding rural areas. Urban wetlands are crucial in mitigating the UHI effect and improving climate resilience via their cooling effect. This study examines Colombo, Sri Lanka, the RAMSAR-accredited wetland city in South Asia, to assess the cooling effect of urban wetlands based on 2023 dry season data for effective sustainable management. We used Landsat 8 and 9 data to create Land Use/Cover (LUC), Land Surface Temperature (LST), and surface-reflectance-based maps using the Google Earth Engine (GEE). The Enhanced Vegetation Index (EVI), Modified Normalized Difference Water Index (mNDWI), topographic wetness, elevation, slope, and impervious surface percentage were identified as the influencing variables. The results show that urban wetlands in Colombo face tremendous pressure due to rapid urban expansion. The cooling intensity positively correlates with wetland size. The threshold value of efficiency (TVoE) of urban wetlands in Colombo was 1.42 ha. Larger and more connected wetlands showed higher cooling effects. Vegetation- and water-based wetlands play an important role in <10 km urban areas, while more complex shape configuration wetlands provide better cooling effects in urban and peri-urban areas due to edge effects. Urban planners should prioritize protecting wetland areas and ensuring hydrological connectivity and interconnected wetland clusters to maximize the cooling effect and sustain ecosystem services in rapidly urbanizing coastal cities. Full article

Forest shelterbelts and windbreaks play a vital role in protecting ecosystems, mitigating climate change effects, and enhancing agricultural productivity. These vegetative barriers serve as effective tools for soil conservation, reducing wind and water erosion while improving soil fertility. Additionally, they contribute to biodiversity preservation by providing habitat corridors for various plant and animal species. Their role in microclimate regulation, such as temperature moderation and increased humidity retention, further enhances agricultural yields and ecosystem stability. This study examines the historical evolution, design principles, and contemporary applications of forest shelterbelts and windbreaks, drawing insights from scientific research and case studies worldwide. It highlights the economic and environmental benefits, including improved air quality, carbon sequestration, and water management, making them crucial components of sustainable land use strategies. However, challenges such as land use competition, maintenance costs, and policy constraints are also analyzed, underscoring the need for integrated approaches to their management. Through a comprehensive bibliometric analysis of the existing literature and field studies, this paper emphasizes the necessity of strategic planning, community involvement, and adaptive policies to ensure the long-term sustainability of forest shelterbelts and windbreaks. The findings contribute to a broader understanding of their role in combating environmental degradation and promoting ecological resilience in the face of ongoing climate challenges. Full article

Background: Patients with chronic kidney disease (CKD) face an elevated risk of cardiovascular disease (CVD), particularly those with estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m². Aims: To assess low-density lipoprotein cholesterol (LDL-C) values and the proportion of pre-dialysis patients achieving national and international targets. Methods: This was a retrospective audit (May–October 2024) of 272 patients aged >18 years attending pre-dialysis clinic (estimated glomerular filtration rate <30 mL/min/1.73 m²) at the Renal Unit, Birmingham Heartlands Hospital. Data on age, sex, ethnicity, body mass index, smoking status, CVD status, hypertension, diabetes, lipids (including LDL-C using the Friedewald and Sampson algorithms) and lipid-lowering therapy were collected from the hospital electronic records. Statistical analyses evaluated factors that were associated with LDL-C (linear/multiple regression) and statin therapy (Chi square). Results: The median (interquartile range) calculated LDL-C values were 2.2 (1.7–2.8) mmol/L and 2.3 (1.7–2.9) mmol/L using the Friedewald and Sampson algorithms respectively. Age and statin therapy were independently associated with LDL-C. Using the Friedewald algorithm, 83.8%, 70.6% and 60.3% did not achieve LDL-C targets of 1.4 mmol/L, 1.8 mmol/L and 2.0 mmol/L respectively, these figures were higher when the Sampson algorithm was applied. Only 18 and 3 of the patients were on ezetimibe and inclisiran respectively, whilst not a single patient was on bempedoic acid or proprotein convertase subtilisin/kexin type 9 inhibitors. Conclusion: Our data highlight deficiencies in the management of LDL-C in advanced CKD. We would recommend greater awareness of LDL-C targets and the use of combination lipid-lowering therapy following optimisation of statin therapy. Full article

To improve the reliability of the shearer output shaft in coal seams with gangue, taking the MG400/951-WD shearer model as the research object, a test system for the physical and mechanical properties of coal seam samples containing gangue was established. Based on the coal breaking theory, the impact load of the spiral drum in a coal seam with gangue was simulated. Combined with rigid-flexible coupling virtual prototype technology, a rigid-flexible coupling virtual prototype model of a shearer with an output shaft as the modal neutral file was established. The output shaft is a typical symmetrical part, and it is of great significance to analyze it by using dynamic theory and mechanical reliability theory. The shearer system modal, the stress distribution of output shaft, and vibration characteristics were obtained by dynamic simulation. Based on resonance failure criterion and combined with a neural network, the output shaft stress reliability, vibration reliability, amplitude reliability, and reliability sensitivity were analyzed under relevant failure modes. The state function of the output shaft reliability optimization design was established, and the structural evolution algorithm obtained the optimal design variables. The results show that the maximum stress of the output shaft is reduced by 14.06%, the natural frequency of the output shaft is increased, the amplitude of the output shaft is reduced by 31.13%, and the reliability of the output shaft is improved. The combination of rigid-flexible coupling virtual prototype technology, reliability sensitivity design theory considering correlated failure modes, and structural evolution algorithm provides a more reliable analysis method for the reliability analysis and design of mechanical equipment transmission mechanisms, which can enhance the reliability of the shearer’s cutting unit and improve safety in fully mechanized coal mining faces. The proposed methodology demonstrates broad applicability in the reliability analysis of critical components for mining machinery, exhibiting universal adaptability across various operational scenarios. Full article

Tunnel lining structures, which are subjected to the combined effects of water and soil pressure as well as a water-rich erosion environment, undergo a corrosion-induced damage and degradation process in the reinforced concrete, gradually leading to structural failure and a significant decline in service performance. By introducing the Cohesive Zone Model (CZM) and the concrete damage plastic model (CDP), a three-dimensional numerical model of the tunnel lining structure in mining method tunnels was established. This model takes into account the multiple effects caused by steel reinforcement corrosion, including the degradation of the reinforcement’s performance, the loss of an effective concrete cross section, and the deterioration of the bond between the steel reinforcement and the concrete. Through this model, the deformation, internal forces, damage evolution, and degradation characteristics of the structure under the effects of the surrounding rock water–soil pressure and steel reinforcement corrosion are identified. The simulation results reveal the following: (1) Corrosion leads to a reduction in the stiffness of the lining structure, exacerbating its deformation. For example, under high water pressure conditions, the displacement at the vault of the lining before and after corrosion is 4.31 mm and 7.14 mm, respectively, with an additional displacement increase of 65.7% due to corrosion. (2) The reinforced concrete lining structure, which is affected by the surrounding rock loads and expansion due to steel reinforcement corrosion, experiences progressive degradation, resulting in a redistribution of internal forces within the structure. The overall axial force in the lining slightly increases, while the bending moment at the vault, spandrel, and invert decreases and the bending moment at the hance and arch foot increases. (3) The damage range of the tunnel lining structure continuously increases as corrosion progresses, with significant differences between the surrounding rock side and the free face side. Among the various parts of the lining, the vault exhibits the greatest damage depth and the widest cracks. (4) Water pressure significantly impacts the internal forces and crack width of the lining structure. As the water level drops, both the bending moment and the axial force diminish, while the damage range and crack width increase, with crack width increasing by 15.1% under low water pressure conditions. Full article

Curved surfaces are a feature of many engineering applications, and as such, the accurate prediction of separation and reattachment from a curved surface is of great engineering importance. In this study, improved delayed detached eddy simulation (IDDES) is used, in conjunction with synthetic turbulence injection using the synthetic eddy method (SEM), to investigate the boundary layer separation from a curved backward-facing step for which large eddy simulation (LES) results are available. The commercial code Star CCM+ was used with the k-ω shear stress transport (SST) variation of the IDDES model to assess the accuracy of the code for this class of problem. The IDDES model predicted the separation length within 10.4% of the LES value for the finest mesh and 25.5% for the coarsest mesh, compared to 36.2% for the RANS simulation. Good agreement between the IDDES and LES was also found in terms of the distribution of skin friction, velocity, and Reynolds stress, demonstrating an acceptable level of accuracy, as has the prediction of the separation and reattachment location. The model has, however, found it difficult to capture the pressure coefficient accurately in the region of separation and reattachment. Overall, the IDDES model has performed well against a type of geometry that is typically a challenge to the hybrid RANS-LES method (HRLM). Full article

While DC/DC converters for water electrolysis systems have been widely investigated, they inherently face a critical compromise between wide voltage regulation capabilities and dynamic response characteristics. This study is based on a two-stage hybrid topology (TSIB-TPLLC) that synergistically combines a two-phase interleaved buck converter with a three-phase LLC resonant converter to resolve this challenge. The first-stage interleaved buck converter enables wide-range voltage regulation while reducing input current ripple and minimizing intermediate bus capacitance through phase-interleaved operation. The subsequent three-phase LLC stage operates at a fixed resonant frequency, achieving inherent output current ripple suppression through multi-phase cancellation while maintaining high conversion efficiency. A dual-loop control architecture incorporating linear active disturbance rejection control (LADRC) with PI compensation is developed to improve transient response compared to conventional PI-based methods. Finally, a 1.2 kW experimental prototype with an input voltage of 250 V and an output voltage of 24 V demonstrates the converter’s operational feasibility and enhanced steady-state/transient performance, confirming its suitability for hydrogen production applications. Full article

Industrial defect detection in edge computing environments faces critical challenges in balancing accuracy, efficiency, and adaptability under data scarcity. To address these limitations, we propose the Hybrid Anomaly Detection System (HyADS), a novel lightweight framework for edge-based industrial defect detection. HyADS integrates three synergistic modules: (1) a feature extractor that integrates Histogram of Oriented Gradients (HOG) and Local Binary Patterns (LBP) to capture robust texture features, (2) a lightweight U-net autoencoder that reconstructs normal patterns while preserving spatial details to highlight small-scale defects, and (3) an adaptive patch matching module inspired by memory bank retrieval principles to accurately localize local outliers. These components are synergistically fused and then fed into a segmentation head that unifies global reconstruction errors and local anomaly maps into pixel-accurate defect masks. Extensive experiments on the MVTec AD, NEU, and Severstal datasets demonstrate state-of-the-art performance. Notably, HyADS achieves state-of-the-art F1 scores (94.1% on MVTec) in anomaly detection and IoU scores (85.5% on NEU/82.8% on Seversta) in segmentation. Designed for edge deployment, this framework achieves real-time inference (40–45 FPS on an RTX 4080 GPU) with minimal computational overheads, providing a practical solution for industrial quality control in resource-constrained environments. Full article