Search Results (1,582)

The Southern Ocean (SO) plays a fundamental role in the planet’s climate system, due to its ability to absorb and redistribute heat and CO₂ (an important greenhouse gas). In addition, the SO connects three large oceanic basins the Pacific, the Atlantic, and the Indian Oceans, and it has an important role in the nutrient distribution in these oceans. However, the SO is poorly sampled, with most measurements made in austral spring and summer. The variability in the air–sea CO₂ flux is estimated, as well as the role of atmospheric and oceanic variables in this variability. The CO₂ fluxes are calculated using the bulk parameterization method, in the Atlantic sector of the Southern Ocean, from 2003 to 2022, using in situ measurements, satellites, and a reanalysis data set. A neural network model is built to produce maps of the partial pressure of CO₂ in seawater (pCO_2sea). The CO₂ flux varies from −0.05 to 0.05 gC m⁻² month⁻¹. The Atlantic sector of the SO is a sink of CO₂ in summer and spring and becomes a source in austral winter and autumn. The CO₂ absorption intensifies from 2003 to 2022 by 7.6 mmol m⁻² month⁻¹, due to stronger westerly winds, related to the trend in the positive phase of the Antarctic Oscillation and the extreme El Niño Southern Ocean (ENSO) events (e.g., El Niño and La Niña). Full article

In elevator systems, pressure plates secure guide rails and limit displacement, but defects compromise their performance under stress. Current detection algorithms face challenges in achieving high localization accuracy and computational efficiency when detecting small defects in guide rail pressure plates. To overcome these limitations, this paper proposes a lightweight defect detection network (LGR-Net) for guide rail pressure plates based on the YOLOv8n algorithm. To solve the problem of excessive model parameters in the original algorithm, we enhance the baseline model’s backbone network by incorporating the lightweight MobileNetV3 and optimize the neck network using the Ghost convolution module (GhostConv). To improve the localization accuracy for small defects, we add a high-resolution small object detection layer (P2 layer) and integrate the Convolutional Block Attention Module (CBAM) to construct a four-scale feature fusion network. This study employs various data augmentation methods to construct a custom dataset for guide rail pressure plate defect detection. The experimental results show that LGR-Net outperforms other YOLO-series models in terms of overall performance, achieving optimal results in terms of precision (p = 98.7%), recall (R = 98.9%), mAP (99.4%), and parameter count (2,412,118). LGR-Net achieves low computational complexity and high detection accuracy, providing an efficient and effective solution for defect detection in elevator guide rail pressure plates. Full article

This study utilized CT scanning and image processing techniques to extract and analyze the internal mesostructure and cement paste distribution of porous concrete. The effects of the mesostructure and cement paste distribution on the compressive strength and permeability were studied. Additionally, the research explored the blockage mechanisms and morphology in porous concrete, with CT scanning used to map the distribution of blockages within the material. The results indicate that the impact of the aggregate particle size on the compressive strength is much less significant than the effect of porosity. The images clearly show that the pore size is positively correlated with both porosity and aggregate size. Additionally, the distributions of pore size and cement paste thickness can be described using a lognormal distribution function and a two-parameter Weibull function, respectively. Blockage analysis revealed that the blockages were primarily concentrated within the top 0–30 mm of the porous concrete surface. As the pore size increases, the blockage depth increases, and blockages in the 10–30 mm range are challenging to remove with high-pressure water jets. A degradation model for the permeability performance of aggregate porous concrete, considering blockage consolidation, was established using parameters such as the blockage accumulation per unit area, aggregate particle size, and concrete porosity. This model provides theoretical and data-based references for evaluating the service life of porous concrete. Full article

Introduction: Microvascular free flap surgery is a treatment method for patients with head and neck cancer requiring reconstruction surgery. Patients undergoing this complex, long-lasting surgery are prone to prolonged episodes of intraoperative hypotension, which is associated with increased incidence of postoperative mortality, morbidity, and free flap failure. A new technology recently approved, named the Hypotension Prediction Index (HPI), allows precise hemodynamic monitoring of patients under general anesthesia, with a significant reduction of intraoperative hypotension events. This study aims to assess the impact of the Hypotension Prediction Index (HPI) on the incidence and severity of intraoperative hypotension in patients undergoing free flap surgery. Methods and analysis: Eligible patients will be randomly assigned to one of two groups: Group A, receiving invasive blood pressure monitoring with standard medical therapy, or Group B, undergoing hemodynamic monitoring using the Hypotension Prediction Index (HPI) software. The primary outcome is the time-weighted average (TWA) of mean arterial pressure (MAP) < 65 mmHg. Secondary outcomes include free flap viability and perioperative complications. Ethics and dissemination: Ethics approval was obtained from the Poznan University of Medical Sciences Ethics Committee (KB-560/22; date 1 July 2022). Results will be submitted for publication in a peer-reviewed journal. Trial registration number: NCT 05738603. Full article

Surfactants significantly influence the flow patterns of gas-liquid two-phase flows. Understanding the behavior of multiphase flows in the presence of surfactants is crucial for optimizing hydrate transport in pipelines. This study presents experimental investigations into the effects of surfactant-induced surface tension variations on gas-liquid two-phase spiral flows in horizontal pipelines. Four distinct flow patterns were identified: spiral linear flow, spiral wave-stratified flow, spiral axial flow, and spiral dispersed flow. Notably, spiral bubbly flow and spiral slug flow were absent in gas-liquid two-phase spiral flows with a low concentration of the anionic surfactant sodium dodecyl sulfate (SDS). A flow pattern map was developed to describe gas-liquid two-phase spiral flows in horizontal pipelines with low SDS concentrations. The results indicate that increasing the liquid-phase velocity reduces the spiral diameter and attenuates the flow patterns while increasing the pitch of the spiral flows. Furthermore, at a constant gas-phase void fraction, the pressure drop is highest in spiral wave-stratified flow and lowest in spiral dispersed flow. Full article

As global environmental consciousness continues to expand, the issue of refrigerant alternatives has increasingly become a focal point for scholarly attention. Using CiteSpace visualization technology, a comprehensive and innovative research framework for refrigerant alternatives has been developed. This framework systematically organizes and analyzes not only the volume of publications related to refrigerant alternatives but also the collaborative relationships among authors and research institutions. By employing keyword co-occurrence maps, clustering diagrams, and timeline charts, an in-depth analysis of the academic literature on refrigerant alternatives has been performed, elucidating the core research themes, evolutionary trajectories, and emerging trends in this field. Research indicates an exponential increase in the number of studies on refrigerant alternatives; however, there is insufficient collaboration and communication among researchers and institutions. Key research hotspots in this field encompass the organic Rankine cycle, vapor-liquid equilibria, pressure drop characteristics, vapor compression refrigeration systems, exergy analysis, alternative refrigerants, and performance evaluation of carbon dioxide systems. In future research, the performance of various low GWP refrigerants in refrigeration cycle systems will continue to be a focal point. To address diverse application requirements, developing blended refrigerants represents a pragmatic technical approach. From a sustainability standpoint, natural refrigerants are anticipated to emerge as the ultimate alternative, with the technical challenges associated with their application constituting a critical area for future investigation. Full article

This research investigates the dynamic behavior of flames generated from methyl laurate droplets using advanced deep learning techniques. By analyzing high-resolution image sequences, we aim to extract valuable insights into the flame’s evolution, including its ignition, growth, and extinction phases. YOLOv9, a state-of-the-art object detection model, is employed to automatically segment and track key flame features such as flame shape, size, and intensity. Our results demonstrate a high accuracy of 0.97 and 0.92 mAP for automatic object segmentation of the flame and droplet. Through quantitative analysis of these features, we seek to gain a deeper understanding of the underlying physical processes governing droplet combustion. The results of this study can contribute to the development of more accurate and efficient combustion models, as well as improved fire safety strategies. This study investigates the combustion dynamics of methyl laurate droplets at atmospheric pressure, providing foundational insights into its behavior as a biodiesel fuel. Future research under high-pressure conditions is recommended to better understand its performance in practical engine applications. Full article

This study aims to determine the potential of the area for diversifying ecologically based tourism and recreation activities, with a focus on balancing conservation and use to reduce the pressures on natural and cultural landscape values. Data related to the area were examined according to sustainable tourism principles, resulting in the identification of five feasible ecologically based tourism and recreation activities. In the subsequent phase, to analyze the compatibility of these activities with the area’s natural and cultural landscape values, suitability class values were mapped using GIS, based on evaluation criteria and indicators. The analysis identified suitable and highly suitable areas for camping, hiking, trekking, landscape, and nature photography, which were marked on the maps. By overlaying the activities, optimal land use was determined to cover 16.25% of the total area. Finally, the activities were assessed within the optimal land use framework using one-way analysis of variance, and relationships between different groups were identified. As a result, the most suitable activities for the study area were landscape and nature photography, while caravan camping was identified as a suitable activity. Full article

Hydrogen leakage in Proton Exchange Membrane (PEM) fuel cells poses critical safety, efficiency, and operational reliability risks. This study introduces an innovative infrared (IR) thermography-based methodology for detecting and quantifying hydrogen leaks towards the outside of PEM fuel cells. The proposed method leverages the catalytic properties of a membrane electrode assembly (MEA) as an active thermal tracer, facilitating real-time visualisation and assessment of hydrogen leaks. Experimental tests were conducted on a single-cell PEM fuel cell equipped with intact and defective gaskets to evaluate the method’s effectiveness. Results indicate that the active tracer generates distinct thermal signatures proportional to the leakage rate, overcoming the limitations of hydrogen’s low IR emissivity. Comparative analysis with passive tracers and baseline configurations highlights the active tracer-based approach’s superior positional accuracy and sensitivity. Additionally, the method aligns detected thermal anomalies with defect locations, validated through pressure distribution maps. This novel, non-invasive technique offers precise, reliable, and scalable solutions for hydrogen leak detection, making it suitable for dynamic operational environments and industrial applications. The findings significantly advance hydrogen’s safety diagnostics, supporting the broader adoption of hydrogen-based energy systems. Full article

Background/Objectives: Porcine reproductive and respiratory syndrome virus (PRRSV) is classified into various lineages based on the phylogenetic variation of orf5, which encodes a major surface glycoprotein GP5 containing both neutralizing and non-neutralizing linear epitopes. Several positively selected sites have been identified on the GP5 ectodomain, indicating host immune pressure on these sites. This present study aimed to investigate the kinetics of antibody responses to GP5 and to map the epitope-specific response to the GP5 ectodomain from different PRRSV lineages after vaccination with commercially available modified live virus (MLV) vaccines. Methods: Post-weaning pigs were vaccinated with MLV vaccines derived from either lineage 1D (Prevacent PRRS^®) or lineage 5 (Ingelvac PRRS^®). Animals were challenged with a heterologous (lineage 1A) strain at 64 days post-vaccination (dpv). Blood samples were collected at various times post-vaccination and challenge. Kinetics of antibody response to different PRRSV antigens were monitored and virus neutralization against archetypal and contemporary strains belonging to lineage 5 and 1A were evaluated. In addition, antibody responses to peptides derived from the GP5 ectodomain of different viral lineages were assessed. Results: Our results showed that the GP5-specific antibody response observed between 18 and 35 dpv was delayed compared to responses to the viral nucleocapsid protein. The polyclonal antibody response in both vaccinated groups showed similar levels of binding to variant GP5 peptides from different sub-lineages. Notably, in both vaccinated groups, the antibody directed to a peptide representing the GP5 ectodomain of a lineage 1C strain (variant 1C.5) displayed a rise in titer at 64 dpv, which was further increased by the challenge with the lineage 1A strain. Less than 50% of animals developed heterologous neutralizing antibodies post-vaccination with both MLV vaccines. However, higher neutralization titers were observed in all vaccinated animal post-challenge. Conclusions: Together, these data provide insights into the antibody responses to the GP5 ectodomain in MLV-vaccinated swine herds. Full article

Background: In the study of coronary artery disease, the mechanisms underlying atherosclerosis initiation and progression or regression remain incompletely understood. Our research conceptualized the cardiovascular system as an integrated network of pumps and pipes, advocating for a paradigm shift from static imaging of coronary stenosis to dynamic assessments of coronary flow. Further review of fluid mechanics highlighted the water hammer phenomenon as a compelling analog for processes in coronary arteries. Methods: In this review, the analytical methodology employed a comprehensive, multifaceted approach that incorporated a review of fluid mechanics principles, in vitro acoustic experimentation, frame-by-frame visual angiographic assessments of in vivo coronary flow, and an artificial intelligence (AI) protocol designed to analyze the water hammer phenomenon within an acoustic framework. In the analysis of coronary flow, the angiograms were selected from patients with unstable angina if they had previously undergone one or more coronary angiograms, allowing for a longitudinal comparison of dynamic flow and phenomena. Results: The acoustic investigations pinpointed pockets of contrast concentrations, which might correspond to compression and rarefaction zones. Compression antinodes were correlated to severe stenosis, due to rapid shifts from low-pressure diastolic flow to high-pressure systolic surges, resulting in intimal injury. Rarefaction antinodes were correlated with milder lesions, due to de-escalating transitions from high systolic pressure to lower diastolic pressure. The areas of nodes remained without lesions. Based on the locations of antinodes and nodes, a coronary acoustic action map was constructed, enabling the identification of existing lesions, forecasting the progression of current lesions, and predicting the development of future lesions. Conclusions: The results suggested that intimal injury was likely induced by acoustic retrograde pressure waves from the water hammer phenomenon and developed new lesions at specifically exact locations. Full article

A novel total joint replacement (TJR) that treats lumbar spine degeneration was previously assessed under Mode I and Mode IV conditions. In this study, we relied on these previous wear tests to establish a relationship between finite element model (FEM)-based bearing stresses and in vitro wear penetration maps. Our modeling effort addressed the following question of interest: Under reasonably worst-case misaligned conditions, do the lumbar total joint replacement (L-TJR) polyethylene stresses and strains remain below values associated with Mode IV impingement wear tests? The FEM was first formally verified and validated using the risk-informed credibility assessment framework established by ASME V&V 40 and FDA guidance. Then, based on criteria for unreasonable misuse outlined in the surgical technique guide, a parametric analysis of reasonably worst-case misalignment using the validated L-TJR FEM was performed. Reasonable misalignment was created by altering device positioning from the baseline condition in three scenarios: Axial Plane Convergence (20–40°), Axial Plane A-P Offset (0–4 mm), and Coronal Plane Tilt (±20°). We found that, for the scenarios considered, the contact pressures, von Mises stresses, and effective strains of the L-TJR-bearing surfaces remained consistent with Mode I (clean) conditions. Specifically, the mechanical response values fell below those determined under Mode IV (worst-case) boundary conditions, which provided the upper-bound benchmarks for the study (peak contact pressure 83.3 MPa, peak von Mises stress 32.2 MPa, and peak effective strain 42%). The L-TJR was judged to be insensitive to axial and coronal misalignment under the in vitro boundary conditions imposed by the study. Full article

Deep mining in metal mines faces more and more complex geological conditions, such as “three highs and one disturbance” (high ground stress, high permeability, high temperature, and mining-induced disturbance), which can easily trigger water inrush disasters and seriously affect the safety and efficiency of deep mining. This paper focuses on the deep hydrogeological structural characteristics of the Huize lead–zinc mine. Firstly, two main factors affecting the production safety of the mining area, namely the water source and water channel of the mine, were analyzed. Based on this analysis, nine factors were determined as indicators for the risk assessment of water inrush, including the water head difference, water-bearing capacity, permeability coefficient, aquifer thickness, water pressure, fault type, fault scale, fault water conductivity, and karst zoning characteristics. Then, a water inrush risk assessment model for the deep mine was constructed, and the weights of the individual factors were determined using the analytic hierarchy process (AHP) and entropy weight method (EWM). Combined with the multi-factor spatial fitting function of the GIS, a zoning map of the risk assessment of water inrush was developed. The results showed that the aquifer groups of the Permian Liangshan Formation and the Carboniferous Maping Formation (P₁l + C₃m) were relatively safe, whereas the karst fissure aquifer of the Qixia–Maokou Formation (P₁q + m) posed a high risk of water inrush, necessitating advanced exploration and water drainage in the area. These findings provide guidance for water control measures in the Huize lead–zinc mine and offer valuable insights into the prediction and prevention of mine water hazards associated with ore body mining in karst aquifers. Full article

China has a vast land area, with mountains accounting for 1/3 of the country’s land area. Flooding in these areas can cause significant damage to human life and property. Therefore, rainstorms and flood hazards in Huangshan City should be accurately assessed and effectively managed to improve urban resilience, promote green and low-carbon development, and ensure socio-economic stability. Through the Random Forest (RF) algorithm and the Soil Conservation Service (SCS) model, this study aimed to assess and demarcate rainstorm and flood hazard risks in Huangshan City. Specifically, Driving forces-Pressure-State-Impact-Response (DPSIR)’s framework was applied to examine the main influencing factors. Subsequently, the RF algorithm was employed to select 11 major indicators and establish a comprehensive risk assessment model integrating four factors: hazard, exposure, vulnerability, and adaptive capacity. Additionally, a flood hazard risk zoning map of Huangshan City was generated by combining the SCS model with a Geographic Information System (GIS)-based spatial analysis. The assessment results reveal significant spatial heterogeneity in rainstorm and flood risks, with higher risks concentrated in low-lying areas and urban fringes. In addition, precipitation during the flood season and economic losses were identified as key contributors to flood risk. Furthermore, flood risks in certain areas have intensified with ongoing urbanization. The evaluation model was validated by the 7 July 2020 flood event, suggesting that Huangshan District, Huizhou District, and northern Shexian County suffered the most severe economic losses. This confirms the reliability of the model. Finally, targeted flood disaster prevention and mitigation strategies were proposed for Huangshan City, particularly in the context of carbon neutrality and green urbanization, providing decision-making support for disaster prevention and emergency management. These recommendations will contribute to enhancing the city’s disaster resilience and promoting sustainable urban development. Full article

Cultural heritage serves as a repository of a place’s history and identity, integral to its landscape and central to all three sustainability goals. However, managing and protecting cultural heritage through regulatory planning often proves inadequate. This particularly applies to islands where infrastructure development pressures and urban sprawl lead to significant changes. This study quantifies the impact of uncontrolled built-up area dispersion on islands’ cultural heritage, focusing on the Southern Aegean region. By identifying and delineating the boundaries of archaeological areas and historic sites, we assess pressures through the mapping and quantitative analysis of built-up areas derived from the Global Monitoring for Environment and Security (GMES) program. The results reveal spatial relations and potential conflicts, underscoring the insufficient protection of cultural heritage due to inadequate management and ineffective planning tools. Specifically, on islands like Mykonos and Naxos, over 80% of their archaeological areas are impacted by urban sprawl. Additionally, this study finds that six islands (Antiparos, Irakleia, Kea, Mykonos, Paros and Patmos) have over 60% of their built-up areas in exurban regions, exacerbating pressures on heritage sites. These findings highlight the need for an integrated spatial planning system that incorporates landscape and cultural heritage assets into strategic planning regulations, ensuring the preservation of these essential resources amidst ongoing development pressures. Full article