Search Results (77)

The Latin American and Caribbean (LAC) region faces persistent challenges of inequality, climate change vulnerability, and deteriorating air quality. The Aburrá Valley, where Medellín is located, is a narrow tropical valley with complex topography, strong thermal inversions, and unstable atmospheric conditions, all of which exacerbate the accumulation of pollutants. In Medellín, ${\mathrm{NO}}_2$ concentrations have remained nearly unchanged over the past eight years, consistently approaching critical thresholds, despite the implementation of air quality control strategies. These persistent high concentrations are closely linked to the variability of the atmospheric boundary layer (ABL) and are often intensified by prolonged dry periods. This study focuses on a representative street canyon in Medellín that has undergone recent urban interventions, including the construction of new public spaces and pedestrian areas, without explicitly considering their impact on ${\mathrm{NO}}_x$ dispersion. Using Computational Fluid Dynamics (CFD) simulations, this work evaluates the influence of urban morphology on ${\mathrm{NO}}_x$ accumulation. The results reveal that areas with high Aspect Ratios (AR > 0.65) and dense vegetation exhibit reduced wind speeds at the pedestrian level—up to 40% lower compared to open zones—and higher ${\mathrm{NO}}_2$ concentrations, with maximum simulated values exceeding 50 μg/m³. This study demonstrates that the design of pedestrian corridors in complex urban environments like Medellín can unintentionally create pollutant accumulation zones, underscoring the importance of integrating air quality considerations into urban planning. The findings provide actionable insights for policymakers, emphasizing the need for comprehensive modeling and field validation to ensure healthier urban spaces in cities affected by persistent air quality issues. Full article

The present study was motivated by the need to enhance indoor air quality and reduce airborne disease transmission in dense urban environments where high-rise residential buildings face challenges in achieving effective natural ventilation. The problem lies in the lack of scalable and convenient tools to optimize natural ventilation rate, particularly in urban settings with varying building heights. To address this, the scientific technique developed with an innovative metric, the urbanized natural ventilation effectiveness factor (uNVeF), integrates regression analysis of wind direction, velocity, air change rate per hour (ACH), window configurations, and building height to quantify ventilation efficiency. By employing a field measurement methodology, the measurements were conducted across 25 window-opening scenarios in a 13.9 m² residential unit on the 35/F of a Hong Kong public housing building, supplemented by the Hellman Exponential Law with a site-specific friction coefficient (0.2907, R² = 0.9232) to estimate the lower floor natural ventilation rate. The results confirm compliance with Hong Kong’s statutory 1.5 ACH requirement (Practice Note for Authorized Persons, Registered Structural Engineers, and Registered Geotechnical Engineers) and achieving a peak ACH at a uNVeF of 0.953 with 75% window opening. The results also revealed that lower floors can maintain 1.5 ACH with adjusted window configurations. Using the Wells–Riley model, the estimation results indicated significant airborne disease infection risk reductions of 96.1% at 35/F and 93.4% at 1/F compared to the 1.5 ACH baseline which demonstrates a strong correlation between ACH, uNVeF and infection risks. The uNVeF framework offers a practical approach to optimize natural ventilation and provides actionable guidelines, together with future research on the scope of validity to refine this technique for residents and developers. The implications in the building industry include setting up sustainable design standards, enhancing public health resilience, supporting policy frameworks for energy-efficient urban planning, and potentially driving innovation in high-rise residential construction and retrofitting globally. Full article

Historical districts are the mark of the continuity of urban history and are non-renewable. Typhoon disasters rank among the most serious and frequent natural threats to China’s coastal regions. Improving the wind resilience of China’s coastal historical districts is of great significance for their protection and inheritance. Accurately analyzing the different characteristics of the influencing factors of wind resilience in China’s coastal historical districts can provide a theoretical basis for alleviating the damage caused by typhoons and formulating disaster prevention measures. This paper accurately identifies the main influencing factors of wind resilience in China’s coastal historical districts and constructs an influencing factor system from four aspects: block level, building level, typhoon characteristics, and emergency management. An IIM model for the systematic analysis of influencing factors of wind resilience in China’s coastal historical districts based on the Improved Decision Making Trial and Evaluation Laboratory (IDEMATEL), Interpretive Structural Modeling (ISM), and Matrices Impacts Croises-Multiplication Appliance Classement (MICMAC) methods is established. This allows us to explore the mechanism of action of internal influencing factors of typhoon disasters and construct an influencing factor system, in order to propose prevention measures from the perspective of typhoon disaster characteristics and the overall perspective of China’s coastal historical districts. The results show that the driving force of a building’s windproof design in China’s coastal historical districts is low, but its dependence is strong; the driving forces of block morphology, typhoon level, and emergency plan are strong, but their dependence is low. A building’s windproof design is a direct influencing factor of the wind resilience of China’s coastal historical districts; block morphology, typhoon level, and emergency plan are the most fundamental and key influencing factors of the wind resilience of China’s coastal historical districts. Full article

Ecuador’s power system has experienced a significant decline in reliability due to its strong reliance on hydroelectric generation, which constituted 67.4% of the national energy mix in 2024. The severe drought of 2023–2024 severely diminished generation capacity, exposing critical vulnerabilities in the National Interconnected System. Under actual operating conditions, the system recorded a loss of load expectation (LOLE) of 91 days per year in 2024. Projections indicate that, without urgent corrective actions, energy deficits could exceed 250 days per year by 2029. Addressing these challenges demands a diversification of the energy matrix, integrating flexible generation sources, energy storage systems, and expanded deployment of solar and wind technologies. Achieving international reliability benchmarks (LOLE ≤ 0.1 days/year) will be essential to ensuring a secure and resilient electricity supply. This study underscores that, without strategic intervention, Ecuador may face prolonged energy crises, offering a cautionary outlook for power systems heavily dependent on climate-sensitive resources. Full article

Climate change significantly impacts agricultural infrastructure, particularly in communal land farming systems, where socio-economic vulnerabilities intersect with environmental stressors. This study examined the effects of extreme weather events (floods, droughts, strong winds, frost, and hail) on various agricultural infrastructures—including bridges, arable land, soil erosion control structures, dipping tanks, roads, and fences—using an ordered probit model. A survey was conducted using structured questionnaires between August and September 2023, collecting data from communal farmers (n = 60) in oKhahlamba Municipality, Bergville. Key results from respondents showed that roads (87%), bridges (85%), and both arable land and erosion structures were reported as highly affected by extreme weather events, especially flooding and frost. Gender, the type of farmer, access to climate information, and exposure to extreme weather significantly influenced perceived impact severity. The ordered probit regression model results reveal that drought (p = 0.05), floods (p = 0.1), strong winds (p = 0.05), and frost (p = 0.1) significantly influence the perceived impacts on infrastructure. Extreme weather events, including flooding (p = 0.012) and frost (p = 0.018), are critical drivers of infrastructure damage, particularly for smallholder farmers. Cumulative impacts—such as repeated infrastructure failure, access disruptions, and increased repair burdens—compound over time, further weakening resilience. The results underscore the urgent need for investments in flood-resilient roads and bridges, improved erosion control systems, and livestock water infrastructure. Support should also include gender-sensitive adaptation strategies, education on climate risk, and dedicated financial mechanisms for smallholder farmers. These findings contribute to global policy discourses on climate adaptation, aligning with SDGs 2 (Zero Hunger), 9 (Industry, Innovation, and Infrastructure), and 13 (Climate Action), and offer actionable insights for building infrastructure resilience in vulnerable rural contexts. Full article

Offshore wind turbines serve as critical infrastructure components in marine renewable energy systems, enabling sustainable energy extraction within offshore engineering frameworks. Monopile foundations for offshore wind turbines in deep-water environments are subjected to strong nonlinear wave actions. This study introduces a novel composite monopile foundation specifically designed for deep-sea applications, with its fully nonlinear hydrodynamic performance systematically investigated using potential flow theory. The novel hybrid monopile incorporates a concrete-filled double-skin steel tubular (CFDST) configuration to reduce pile diameter at water level. In the numerical model, the higher-order boundary element method (HOBEM) is implemented to resolve boundary value problems at each temporal iteration. Following numerical validation, nonlinear wave loading and run-up characteristics for the CFDST hybrid structure are quantified, while the limitations of Morison’s equation for large-scale structures under strongly nonlinear wave conditions are concurrently assessed. Results indicate that CFDST implementation effectively attenuates both nonlinear hydrodynamic forces and wave run-up amplitudes, enabling safer and more economical design approaches for deep-water offshore wind turbine foundations. Full article

The response of large temporary working platforms for cross-sea bridges under the action of strong wind and waves with large tidal ranges is one of the key issues in offshore engineering. Based on a grand offshore bridge project in Fujian Province of China, on-site monitoring tests were carried out on a temporary working platform. A high-precision and fully automatic monitoring system was adopted to conduct the all-weather and high-frequency monitoring on vibrations, responses, and sea conditions of the platform, enabling us to grasp its structural mechanical characteristic and ensuring the platform safety. The results show that, under the severe sea conditions of typhoons, the stress of the platform structure increases significantly with the increase in the tidal range and reaches its maximum value at the high tide level. The inclination angle changes violently at the high tide level, while the amplitude of inclination angle change is relatively small at the low tide level. The effective value of the platform displacement under the severe sea conditions of typhoon meteorology is much larger than that under normal sea conditions. Compared with the low tide level, the acceleration of the offshore temporary work platform changes more drastically at the high tide level under severe sea conditions. Under severe sea conditions, the tidal level has a significant impact on the frequency corresponding to the peak value of the acceleration power spectrum of the offshore temporary platform. Full article

Ipomoea pes-caprae (L.) Sweet (Convolvulaceae) is a commonly used marine Chinese medicine in the coastal areas of southern China. Traditionally, it has been used in the treatment of rheumatoid arthritis (RA). However, the mechanism of action against RA remains unclear. This study aimed to explore the mechanism of action of Ipomoea pes-caprae water extract (IPE) in the treatment of RA through serum metabolomics and network pharmacology. Rat models of RA with wind-dampness cold bi-syndrome (WCM) and wind-dampness heat bi-syndrome (WHM) were established to evaluate the therapeutic effect of IPE against RA. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) technology was used to analyze the absorbed components of IPE in the plasma of the two models. Serum metabolomics was employed to identify potential biomarkers and metabolic pathways of IPE in the treatment of RA. The key targets and related pathways of RA were screened using network pharmacology and validated using molecular docking. The biomarker-pathway-target network was mapped via the combination of metabolomics and network pharmacology. A total of 10 chemical constituents were identified from WHM rat plasma, and eight chemical constituents were identified from WCM rat plasma. Serum metabolomics research identified 20 endogenous potential biomarkers, and 10 major metabolic pathways closely related to WHM and WCM. Network pharmacology analysis yielded 65 overlapping targets, with the core targets being ALB, AKT1, EGFR, and CASP3. Molecular docking showed that the four absorbed components in plasma had a strong binding activity with ALB and AKT1. Combining metabolomics and network pharmacology, two major biomarkers and two major pathways were identified. IPE can effectively relieve the symptoms of RA, and the potential mechanism of IPE in treating RA has been preliminarily elucidated. These results can provide a scientific basis for further drug research and development, as well as clinical application. Full article

A cornerstone of climate action plans around the world, wind power is increasingly recognised as a primary source of clean, sustainable energy. Amidst the escalating challenges of global climate change, wind energy provides an essential balance, enabling environmental progress without compromising economic resilience. However, the significant investment costs associated with wind turbines require careful evaluation alongside the projected energy output to ensure both financial viability and operational efficiency. Given the localised nature of wind resources, it is essential that analysis and feasibility studies are carried out on a regional scale to take account of geographical and climatic variations, thereby maximising the effectiveness of wind energy deployment. This study presents a comprehensive analysis of wind turbine deployment in the Eastern Thrace region, using region-specific energy data and wind characteristics together with performance data from twenty comparable installations in the area. A Monte Carlo-based numerical simulation approach using probabilistic models was applied to provide valuable insights into the financial viability of wind energy investment in the region. The results show a strong potential for cost-effective wind power generation in Eastern Thrace, with an estimated 90% probability of achieving payback within five years. These results underline the economic and environmental benefits of wind energy, confirming its attractiveness to investors and its role as a key driver of sustainable development in the region. Full article

In this paper, a brief review regarding the hydrodynamic circulation of the Mediterranean gulfs is presented. Studies concerning the hydrodynamics of the Mediterranean gulfs with significant environmental and commercial importance were gathered as an initial insight of studies in the Mediterranean microtidal environment. Numerical models, field measurements, and satellite images are the methods used by the investigators for the description and prediction of the circulation in the gulfs. The basic hydrodynamic characteristics of the gulfs are mainly defined by the wind action and less by tide and baroclinicity. Most of the gulfs are characterized by a cyclonic wind-driven circulation, since the tidal effect remains weak in the Mediterranean basin. However, tidal resonance and strong currents are evident in the shallow coastal areas as well as in the wider area of straits. Basic gulfs’ characteristics are summarized in a table that gives an overview of the main Mediterranean gulfs, which can be especially useful for young researchers or new hydroenvironmental studies in the Mediterranean marine and coastal environment. Full article

Post-harvest pre-cooling of water bamboo shoots (WBS) [Zizania latifolia] can effectively delay its quality deterioration. Six types of pre-cooling treatments were used to pre-cooling post-harvest WBS, including cold slightly acidic electrolytic water pre-cooling (CSAEW), cold water pre-cooling (CWPC), vacuum pre-cooling (VPC), strong wind pre-cooling (SWPC), refrigerator pre-cooling (RPC), and fluid ice pre-cooling (FIPC). The effects of different pre-cooling treatments on the quality of refrigerated WBS were investigated. The results showed that the FIPC treatment was harmful to the storage quality of WBS, while the other five pre-cooling treatments could extend the shelf life of WBS to some extent. These pre-cooling treatments can inhibit the respiration of WBS, slow down its weight loss and lignification process, and maintain its relatively high levels of nutrient content and antioxidant activity. The CSAEW treatment outperformed other treatments in terms of bactericidal action and microbiological content control for WBS during storage. The protective effect of CSAEW treatment on the storage quality of WBS was relatively the best, and extended the shelf life of WBS by 12 days compared to the control group. This study indicated that the CSAEW pre-cooling treatment offers a new choice for pre-cooling root vegetables. Full article

The present research was carried out in stands of Scots pine and black pine, pure or mixed with deciduous trees, installed on degraded lands from the Curvature Subcarpathian area, Romania, in a representative network of permanent research plots and followed the analysis of the structural diversity and stability indicators of these stands at different ages and in different conditions of degraded lands. The relationships between the quantitative variables with reference to the structure were established by analyzing the significance of the Pearson correlation coefficient (r) and also including datasets of slenderness indexes, which were classed into three domains of vulnerability to abiotic factors (like wind and snow). The compositional diversity of pine stands (pure or mixed with deciduous ones) is different in relation to age and is correlated with the structural diversity. The obtained correlation coefficients (r Pearson) express very strong and significant relationships between biometric parameters (h x Dbh, h x Lc%, Dc x Dbh, and Lc% x Dbh) of the structural diversity (r = 0.800–0.930), which is important for the analysis of the stability and vulnerability of pine forests. The strong correlation between the analyzed variables expresses a weak vulnerability to the action of harmful abiotic factors and the increase in the stability and resilience of the studied stands, especially of over 50 years old. In the old pine stands, the low-vulnerability domain (I < 0.80) is the best represented one, with an average of 64.01% from the total number of trees. At this age, trees with DBH > 22 cm fall into the low-vulnerability category. The explanation is that the stands were affected in their youth by the action of snow and wind, which, combined with the silvotechnical works performed, led to their compositional and structural diversification and increased stability. The young (<45 years) and pure-pine stands with higher consistency (>0.8) and even-aged structure are the most vulnerable to abiotic factors due to the fact that a large number of trees are passing gradually into the higher cenotic classes. Full article

The wake behind an aircraft carrier under heavy wind condition is a key concern in ship design. The Chinese Liaoning ship’s upturned bow and the island on the deck could cause serious flow separation in the landing and take-off area. The flow separation induces strong velocity gradients and intense pulsations in the flow field. In addition, the sway of the aircraft carrier caused by waves could also intensify the flow separation. The complex flow field poses a significant risk to the shipboard aircraft take-off and landing operation. Therefore, accurately predicting the wake of an aircraft carrier during wave action motion is of great interest for design optimization and recovery aircraft control. In this research, the aerodynamic around an aircraft carrier (i.e., Liaoning) was analyzed using the computational fluid dynamics technique. The validity of two turbulence models was verified through comparison with the existing data from the literature. The upturned bow take-off deck and the right-hand island were the main areas where flow separation occurred. Delayed detached eddy simulation (DDES), which combines the advantages of LES and RANS, was adopted to capture the full-scale spatial and temporal flow information. The DDES was also coupled with the overset grid to calculate the flow field characteristics under the effect of hull sway. The downwash area at 15° starboard wind became shorter when the hull was stationary, while the upwash area and turbulence intensity increased. The respective characteristics of the wake flow field in the stationary and swaying state of the ship were investigated, and the flow separation showed a clear periodic when the ship was swaying. Comprehensive analysis of the time-dependent flow characteristic of the approach line for fixed-wing naval aircraft is also presented. Full article

Jiangsu is a province in China and has the highest frequency of tornado occurrences. Studying the meteorological background and mechanisms of tornado formation is crucial for predicting tornado events and preventing the resulting disasters. This paper analyzed the meteorological background, instability mechanisms, and lifting conditions of the two Enhanced Fujita Scale level 2 (EF2) and above tornadoes that occurred in southern Jiangsu on 14 May 2021 (“5.14”) and 6 July 2020 (“7.06”) using ERA5 reanalysis data. Detailed analyses of the internal structure of tornado storms were conducted using Changzhou and Qingpu radar data. The results showed that (1) both tornadoes occurred in warm and moist areas ahead of upper-level troughs with significant dry air transport following the cold troughs. The continuous strengthening of low-level warm and moist advection was crucial in maintaining potential instability and triggering tornado vortices. The 14 May tornado formed within a low-level shear line and a warm area of a surface trough, while the 6 July tornado occurred at the end of a low-level jet stream, north of the eastern section of a quasi-stationary front. (2) The convective available potential energy (CAPE) and K indices for both tornado processes were very close (391 for “5.14” and 378 for “7.06”), with the lifting condensation level (LCL) near the ground. The “5.14” showed greater instability and more favorable thermodynamic conditions, with deep southwesterly jets at the mid-level shear line producing rotation under strong convergent action (convergence center value exceeding −1 $\times {10}^{-4}$${\mathrm{s}}^{-1}$). In contrast, the “7.06” was driven by super-low-level jet stream pulsations and wind direction convergence under the influence of the Meiyu Front (convergence center value exceeding −1.5 $\times {10}^{-4}$ ${\mathrm{s}}^{-1}$), resulting in intense lifting and vertical vorticity triggered by a surface convergence line. (3) The “5.14” tornado process involved a supercell storm over a surface dry line experiencing tilting due to strong vertical wind shear, which led to the formation of smaller cyclonic vortices near a hook echo that developed into a tornado. The “7.06” developed on a bow echo structure within a mesoscale convective system formed over the Meiyu Front, where dry air subsidence, entrainment, and convergence of the southeast jet stream triggered a “miniature” supercell. The relevant research results provide a reference for the prediction and early warning of tornadoes. Full article

In view of the great impact of the pipeline system in a delayed coker unit (DCU) on production and operation safety, we applied computational fluid dynamics (CFD) to investigate the flow in a fractionator overhead vapor line connected to an air cooler in a previous study. The causes of the pipeline damage and the strategies to alleviate the occurrence of the damage were discussed. It is found that if two 24″ pipes are connected and five 18″ pipes are also connected, the force uniformity can be improved, and the forces on the caps, reducers, and T-junctions can be reduced. In this paper, we further applied the finite element method to perform structure analysis to confirm the strength of the original and the improved pipeline system. It is found that the static stress is larger when the pipelines are connected. The first four modes of the pipeline vibration are primarily affected by the vibration of the 30″ main pipe, while the fifth and the sixth modes are primarily affected by the vibration of the smaller pipes. In the case of a magnitude 1 earthquake (parallel mode) and a magnitude 2 wind, the maximum harmonic response stresses (stresses obtained from harmonic response analysis) occur at the same locations. After the pipelines are connected, some positions of the maximum harmonic response stresses are shifted from the 30″ main pipe to the 24″ pipe. In terms of the wind effect, the pipelines connected or unconnected can both withstand moderate typhoons of magnitude 13 without fatigue damage. In terms of the seismic effect, the pipelines connected can withstand a strong earthquake of magnitude 5(+) without fatigue damage, while the pipelines unconnected can withstand a very strong earthquake of magnitude 6(−) without fatigue damage, which is better than the pipelines connected. Under the action of a magnitude 17 severe typhoon, the stresses for the pipelines connected or unconnected are both lower than the yield strength and the ultimate tensile strength (UTS). There is no danger of immediate damage in terms of the wind effect. The pipelines connected or unconnected can withstand magnitude 7 earthquakes up to accelerations of 1718 gal (17.18 m/s²) and 2236 gal (22.36 m/s²), respectively, without exceeding the UTS. The pipelines unconnected are slightly better than the pipelines connected in terms of earthquake resistance. The purpose of this series study is to explore the flow development and the structural strength of the DCU pipeline system to improve its operational safety. Full article