Search Results (2,796)

It is recognized that a ship’s performance, speed, fuel consumption, and resistance are impacted by the marine environment. The magnitude of this effect, which can be altered by ship design and operational conditions, necessitates added resistance calculations for optimizing these phases. Ship designers can generate efficient hull forms and operators can make sound navigational decisions to reduce emissions within the service zone. For this research, air and wave resistances were calculated using the KCS hull form with a superstructure during a simulated voyage in the North Pacific Ocean. To verify the results, data from towing tank tests available in the literature were used, along with calm water resistance calculations obtained from a computational fluid dynamics (CFD) analysis conducted for this study. When transporting 3600 loaded containers, sea conditions at model-scale impact the ship’s power requirements, leading to air resistance from the superstructure (aerodynamic) and hull resistance from head waves. This research compares the increased wave and air resistance with calm water resistance to provide important insights into the main engine power requirements when traveling in this region. Cruising between 14 and 18 knots generates 8–11% added resistance when encountering head waves at Sea State 5. Full article

Building energy consumption is a major source of carbon emissions, with the heating energy demand of rural buildings in the hot summer and cold winter (HSCW) zone having increased 575-fold over the past 15 years. This research investigated an optimized solar–air source heat pump (SASHP) system to meet the heating demand of rural residences in this region. First, a typical rural building model was developed using SketchUp, and its heating load was simulated using TRNSYS, revealing an average load of 3.38 kW and a peak load of 5.9 kW. Based on the latest technical standards, the SASHP system was designed and simulated using TRNSYS, achieving an overall coefficient of performance (COP) of 3.67 while maintaining indoor thermal comfort within ISO 7730 Category II. Subsequently, the system was optimized through GenOpt to minimize the annual equivalent cost, yielding key parameters: a 15 m² solar collector at a 40.75° tilt, a 0.35 m³ water tank, and a 10.16 kW air source heat pump. Compared with the initial design, the optimized configuration achieved reductions of 35.60% in initial investment and 32.68% in annual equivalent costs. By ensuring thermal comfort and overcoming the economic barrier, this study provides a viable pathway for adoption and promotion of renewable heating technology in rural areas. Full article

To overcome the limitations of lengthy laboratory testing cycles and insufficient on-site responsiveness, this study developed an online rapid monitoring device for volatile organic compounds (VOCs) in soil–water–air systems based on photoionization detection (PID) technology. The device integrates modular sensor units, incorporates an electromagnetic valve-controlled multi-medium adaptive switching system, and employs an internal heating module to enhance the volatilization efficiency of VOCs in water and soil samples. An integrated system was developed featuring “front-end intelligent data acquisition–network collaborative transmission–cloud-based warning and analysis”. The effects of different temperatures on the monitoring performance were investigated to verify the reliability of the designed system. A polynomial fitting model between concentration and voltage was established, showing a strong correlation (R² > 0.97), demonstrating its applicability for VOC detection in environmental samples. Field application results indicate that the equipment has operated stably for nearly three years in a mining area of Shandong Province and an industrial park in Anhui Province, accumulating over 600,000 valid data points. These results demonstrate excellent measurement consistency, long-term operational stability, and reliable data acquisition under complex outdoor conditions. The research provides a distributed, low-power, real-time monitoring solution for VOC pollution control in mining and industrial environments. It also offers significant demonstration value for standardizing on-site emergency monitoring technologies in multi-media environments and promoting the development of green mining practices. Full article

Rain-on-snow (ROS) events significantly impact hydrological processes in snowy regions, yet their seasonal drivers remain poorly understood, particularly in low-elevation and low-gradient catchments. This study uses an XGBoost-SHAP explainable artificial intelligence (XAI) model to analyze meteorological and watershed controls on ROS runoff in the Laurentian Great Lakes region. We used daily discharge, precipitation, temperature, and snow depth data from 2000 to 2023, available from HYSETS, to identify ROS runoff. The XGBoost model’s performance for predicting ROS runoff was higher in winter (R² = 0.65, Nash–Sutcliffe = 0.59) than in spring (R² = 0.56, Nash–Sutcliffe = 0.49), indicating greater predictability in colder months. The results reveal that rainfall and temperature dominated ROS runoff generation, jointly explaining more than 60% of total model importance, while snow depth accounted for 8–12% depending on season. Winter runoff is predominantly governed by climatic factors—rainfall, air temperature, and their interactions—with soil permeability and slope orientation playing secondary roles. In contrast, spring runoff shows increased sensitivity to land cover characteristics, particularly agricultural and shrub cover, as vegetation-driven processes become more influential. Snow depth effects shift from predominantly negative in winter, where snow acts as storage, to positive contributions in spring at shallow to moderate depths. ROS runoff responded positively to air temperatures exceeding approximately 2.5 °C in both winter and spring. Land cover influences on ROS runoff differ by vegetation type and season. Agricultural areas consistently increase runoff in both seasons, likely due to limited infiltration, whereas shrub-dominated regions exhibit stronger runoff enhancement in spring. The seasonal shift in dominant controls underscores the importance of accounting for land–climate interactions in predicting ROS runoff under future climate scenarios. These insights are essential for improving flood forecasting, managing water resources, and developing adaptive strategies. Full article

This study investigates the hydraulic transient behavior and optimization of air-vent configurations in the combined tailrace–diversion system of a hydropower station. The inlet flow boundary conditions were derived from the method of characteristics (MOC), and flow variations were incorporated into the CFD model using a user-defined function (UDF). The CFD results were validated by comparing them to MOC-based simulations of surge oscillations in the downstream chamber. Six different air-vent configurations, varying in number and diameter, were tested under high-water-level load-acceptance and load-rejection conditions. The results demonstrate that increasing the vent diameter, particularly to 3 m, significantly improves pressure regulation and air exchange efficiency, enhancing system stability. In contrast, simply increasing the number of vents did not lead to noticeable improvements. Sensitivity analysis of vent height revealed that raising the vent height from 12 m to 15 m provides sufficient freeboard to prevent overflow, without overdesign. These findings provide practical guidance for optimizing air-vent configurations in hydropower tailrace systems, improving hydraulic stability, and ensuring safe operation. Full article

This study investigates the photocatalytic degradation of organic compounds on TiO₂-coated concrete paving cubes, with a focus on their potential for environmental remediation in urban settings. The TiO₂ P25 coating significantly enhanced the photocatalytic activity of the concrete surface, enabling effective degradation of model pollutants such as methylene blue. Various application methods were evaluated, including surface coating with and without impregnation, and bulk incorporation of TiO₂ into the concrete matrix. Surface properties were assessed using contact angle measurements and absorption tests. Among all tested variants, the surface-coated and impregnated sample (SURF-IMP) showed the highest photocatalytic efficiency, achieving over 67% pollutant degradation. This variant also demonstrated the lowest water absorption and the highest contact angle, confirming improved surface hydrophobicity. In contrast, the bulk-modified sample (MIX) exhibited weaker performance due to limited surface accessibility of TiO₂ particles. These findings highlight the importance of the application method in optimizing the performance of TiO₂-functionalized concrete. The developed system offers a practical approach to integrating photocatalytic properties into paving materials for applications such as air purification, surface decontamination, and sustainable urban infrastructure. Full article

This work illustrates a machine learning methodology to forecast pipe failure frequencies in drinking water systems to enhance asset management and operational planning. Three supervised regression models—Random Forest Regressor (RFR), Extreme Gradient Boosting (XGB), and Multi-Layer Perceptron (MLP)—were developed and evaluated using historical failure data from Malatya, Türkiye. The primary predictive variables identified were pipe diameter, pipe type, pipe age, and seasonal average ambient air temperature. The MLP demonstrated superior performance compared to the other models, attaining the lowest RMSE (1.48) and the highest R² (0.993) with respect to the training data, effectively capturing the nonlinear characteristics and failure patterns. The MLP was validated using two datasets from 24 District Metered Areas (DMAs) in Sakarya and Kayseri, Türkiye. The model’s anticipated failure frequencies exhibited strong concordance with the observed failure frequencies, even in regions of elevated failure density, indicating the model’s proficiency in identifying high-risk locations and facilitating the prioritization of maintenance activities. The work demonstrates the potential of machine learning in water infrastructure management. It emphasizes the importance of employing a hybrid method with Geographic Information Systems (GISs) in future research to enhance forecast accuracy and spatial analysis. Full article

To investigate the deformation characteristics of loess in the Yangling region of Shaanxi Province, China, under different wet-dense states, a fully automatic air pressure consolidation apparatus was used to conduct compression and collapsibility tests. The compression and collapsible deformation mechanisms were revealed from the evolution patterns of compression yield pressure, compression coefficient, and collapsible coefficient. The tests results indicate the following: (1) the greater the compaction degree and the smaller the initial water content, the smaller the amplitude of the compression curve change, the greater the compressive yield stress, and the smaller the compression coefficient; a compression curve model considering initial water content and compaction degree was constructed. (2) The collapsibility coefficient shows a trend of first increasing and then decreasing under low pressure compaction and high initial water content, while under high pressure compaction and low initial water content, it exhibits a continuous increase. The increase in compaction degree and initial water content will both lead to a decrease in the coefficient of collapse. The collapsibility coefficient exhibits a more pronounced response under high pressure compared to low pressure. Soil samples with low compaction and low initial water content demonstrate significantly greater collapsibility sensitivity. (3) A collapsible prediction model applicable to Yangling loess was established based on SPSS software, and the research findings can offer theoretical support for the rapid assessment of loess collapsibility in this region. Full article

This study conducts a numerical investigation of the geometry of the oscillating water column (OWC) wave energy converter under realistic irregular wave conditions found off the coast of Rio Grande, southern Brazil. Two OWC models were compared: the conventional design and the L-shaped configuration (L-OWC). The OWC structure consists of a hydropneumatic chamber and an air duct, where a turbine is coupled to an electric generator. Additionally, in the L-shaped chamber configuration, a water intake duct is considered. The constructal design method was employed for the geometric evaluation of the devices. For the L-OWC, the influence of the height-to-length ratio of the water intake duct on the obtained hydropneumatic power available was analyzed. In parallel, for the conventional OWC, the free-board submergence was investigated. Subsequently, the optimal geometry for each OWC model was selected to study the height-to-length ratio of the hydropneumatic chamber. Numerical simulations were performed using ANSYS Fluent software. Thus, the performance of the converters was improved by approximately 35.76 times for the L-OWC and 3.78 times for the conventional OWC. However, it is noteworthy that the optimal configuration of the conventional OWC achieved a performance 2.62 times higher than the optimal L-OWC geometry. Full article

This study numerically investigates the deformation and consolidation behavior of high-water-content river sediment improved by a combined vacuum preloading and internal air-bag pressurization (VPA) system. A 2D axisymmetric finite-element model in Abaqus 2021 with the Modified Cam-Clay constitutive law is established to simulate the treatment process. Key design parameters—air-bag pressure, pressurization timing, embedment depth, and staged loading—are systematically analyzed. Results show that: (1) Under a −80 kPa vacuum, an additional 20 kPa air-bag pressure reduces the maximum inward horizontal displacement by over 20%, while effective stress increases linearly with pressure; (2) Early pressurization (20 days) better controls lateral deformation and accelerates strength gain; (3) Staged pressurization (20 kPa upper, 40 kPa lower) outperforms uniform loading in both displacement control and cost-effectiveness; (4) Compared to 30 kPa surcharge preloading, VPA further reduces horizontal displacement by 10–18% under equivalent total load. The hybrid “vacuum–air-bag–surcharge” scheme yields the highest effective stress and smallest lateral deformation. The VPA method enhances sediment engineering properties, providing a viable approach for resource utilization of dredged materials. Full article

Ground-penetrating radar (GPR) is widely used for thickness or compaction degree detection of asphalt pavement layers, where the dielectric properties of asphalt mixtures serve as a key parameter influencing detection accuracy. These properties are closely related to the composition of the mixture and are susceptible to environmental factors such as water or ice. To clarify the influence of various factors on the dielectric behavior of asphalt mixtures, an experimental study was conducted under controlled environmental conditions. Asphalt mixture specimens with different air void contents (5.49~10.29%) were prepared, and variables such as void fraction, moisture, and ice presence were systematically controlled. Air-coupled GPR was employed to measure the specimens, and the relative permittivity was calculated using both the reflection coefficient method (RCM) and the thickness inversion algorithm (TIA). Discrepancies between the two methods were compared and analyzed. Results indicate that the RCM is significantly influenced by surface water or ice and is only suitable for dielectric characterization under dry pavement conditions. In contrast, the TIA yields more reliable results across varying surface environments. A unified model (the optimized shape factor u = −4.5 and interaction coefficient v = 5.1) was established to describe the relationship between the dielectric properties of asphalt mixtures and their volumetric parameters (bulk specific density, air void content, voids in mineral aggregate, and voids filled with asphalt). This study enables quantitative analysis of the effects of water, ice, and mixture composition on the dielectric properties of asphalt mixtures, providing a scientific basis for non-destructive and accurate GPR-based evaluation of asphalt pavements. Full article

Air travel contributed 3.5% to global warming in 2020, with a rising tendency. Only one third of the climate impact is caused by CO₂. Other exhaust gases that cause harm to the climate are nitrogen oxides, soot, and water vapor, creating contrails with a negative impact on earth’s albedo. Hence, it is important to reduce any type of emission. As the effects of global climate change become an unneglectable threat to society, calls for quick changes become prominent. Recognizing the need for disruptive changes in air transport, the LuFo-project 328eHY-TECH was initiated to investigate the potential of regional hybrid-electric aircraft. This article focuses on conceptual aircraft design. An aircraft resembling the D328eco is modeled as a baseline aircraft, on which the sizing of the hybrid-electric propulsion systems is performed. As aircraft are mostly operated on a typical mission, which is shorter than the design mission, a distance of 400 nm is found to be a feasible range for this regional aircraft. In a conducted range study, the potential of state-of-the-art battery properties is being investigated and found to be insufficient. Subsequently conducted trade-off studies show that a 104 kW horsepower electric motor and a battery of 1.8 kWh/kg are needed to save 5% block fuel on a mission with 40 passengers of 95 kg over a distance of 400 nm. It is concluded that changing solely the propulsion system will not yield feasible aircraft designs in the near and midterm future. Full article

In heating, ventilation, and air conditioning (HVAC) systems, chiller power model prediction is crucial for control and improving energy efficiency. However, in practical engineering scenarios, the chilled water supply temperature, chilled water flow rate, etc., are mostly set manually, and the system operates at a small number of fixed and sparse operating points. This leads to sparse data availability for model prediction, which seriously limits the prediction accuracy of data-driven models (such as fully connected neural networks). To overcome the above problems, this paper introduces a Physics-Informed Neural Network (PINN), and by embedding physical knowledge, performs predictive modeling of the power of the core equipment in the chiller system—the chiller, condenser water pump, and chilled water pump. Based on the real industrial data of a large building in southern China, the qualitative and quantitative verification shows that the model proposed in this paper has significant advantages in prediction accuracy compared with traditional methods. Full article

Climate change has exacerbated the occurrence of complex extreme hydrological events in high-latitude cold regions, among which drought–flood abrupt events (DFAAEs) threaten food and water security, and accurately predicting their future evolution remains a key challenge. This study used the Community Water Model (CWatM) hydrological model, combined with five CMIP6 climate models, to simulate runoff datasets for historical periods (1985–2014) and future shared socioeconomic pathways (SSPs: SSP126, SSP370, SSP585: 2015–2100). We calculated the DFAA index (DFAAI), analyzed the spatiotemporal distribution patterns and predicted future trends of DFAAEs in the Heilongjiang River Basin, and explored their climatic driving mechanisms. The main conclusions are as follows: (1) Under SSPs, precipitation and evaporation increase from northwest to southeast, and temperature increases from north to south; hotspots expand inland. By 2100, annual precipitation will reach 655, 700, and 720 mm; mean air temperature will rise by 3, 6, and 7 °C; and annual evapotranspiration will reach 460, 515, and 521 mm. (2) Relative to the historical period, DFAAEs increase from 5.9 to 6.6, 7.1, and 7.5 events per year (SSP126/370/585). Coverage rises from 10.6% to 12.7%, 17.1%, and 19.0%, while mean intensity remains 1.8–2.0. Across both the historical period and SSPs, the shares of light (69–74%), moderate (20–24%), and severe (6–8%) events are stable. (3) Principal Component 1 (PC1,62.9%) reflects a precipitation-dominated wetting mode with synchronous increases in evapotranspiration and is the primary driver of DFAAI variability. PC2 (20.3%) captures an energy-related mode governed mainly by evapotranspiration and indirectly modulated by air temperature, providing a secondary contribution. These results clarify DFAA mechanisms and inform water-resources security planning in the Heilongjiang River Basin. Full article

Introduction: Chest drainage is central to thoracic surgery, pleural medicine, and emergency care, yet practice remains heterogeneous in tube caliber, access, suction, device selection, and removal thresholds. This narrative review aims to synthesize evidence and translate it into guidance. Materials and Methods: We performed a narrative review with PRISMA-modeled transparency. Using backward citation from recent comprehensive overviews, we included randomized trials, meta-analyses, guidelines/consensus statements, and high-quality observational studies. We extracted data on indications, technique, tube size, analog versus digital drainage, suction versus water-seal drainage, removal criteria, and key pleural conditions. Due to heterogeneity in device generations, suction targets, and outcomes, we synthesized the findings qualitatively according to converged evidence. Results: After lung resection, single-drain strategies, early use of water-seal, and standardized removal at ≤300–500 mL/day reduce pain and length of stay without increasing the need for reintervention; digital systems support objective removal using sustained low-flow thresholds (approximately 20–40 mL/min). Small-bore (≤14 Fr) Seldinger catheters perform comparably to larger tubes for secondary and primary pneumothorax and enable ambulatory pathways. In trauma, small-bore approaches can match large-bore drainage in stable patients when paired with surveillance and early escalation of care. For pleural infection, image-guided drainage, combined with fibrinolytics or surgery, is key. Indwelling pleural catheters provide relief comparable to talc in dyspnea associated with malignant effusions in patients with non-expandable lungs. Complications are mitigated by ultrasound guidance and avoiding abrupt high suction after chronic collapse; however, these strategies must be balanced against risks of malposition, occlusion or retained collections, prolonged air leaks, and device complexity, which demand protocolized escalation and team training. Conclusions: Practice coalesces around three pillars—right tube, right system, proper criteria. Adopt standardized pathways, device-agnostic thresholds, and volume or airflow criteria. Trials should harmonize “seal” definitions and validate telemetry-informed removal strategies. Full article