Search Results (2,948)

Transparent building envelopes significantly increase energy demands due to low thermal resistance and solar heat gain, while conventional double-skin facades may lead to overheating and high cooling loads in the summer. This study proposes a novel earth-to-air heat exchanger (EAHE)-assisted ventilated double-skin facade (VDSF) system utilizing low-grade shallow geothermal energy for year-round thermal regulation of transparent building envelopes. A numerical model of this coupled system was developed and validated to estimate the thermal performance of the EAHE-assisted VDSF system in a hot-summer-and-cold-winter climate. Parametric study was conducted to investigate the impact of some key design parameters on thermal performance of the EAHE-assisted VDSF system and further reveal recommended design parameters of this coupled system. The results indicate that the EAHE-VDSF system reduces annual accumulated cooling loads by 20.3% to 76.5% and heating loads by 19.6% to 47.1% in comparison to a conventional triple-glazed, non-ventilated facade. The cavity temperature of the VDSF decreases by 15 °C on average in the summer, effectively addressing the overheating issue in DSFs. The proposed coupled EAHE-VDSF system shows promising energy-saving potential and ensures stability and consistency in the thermal regulation of transparent building envelopes. Full article

As climate variability intensifies, its impacts are increasingly visible through disrupted agricultural systems and rising food insecurity, especially in climate-sensitive regions. This study explores the complex relationships between environmental stressors, such as rising temperatures, erratic rainfall, and soil degradation, with food insecurity outcomes in selected districts of Uttarakhand, India. Using the Fuzzy DEMATEL method, this study analyzes 19 stressors affecting the food supply chain and identifies the nine most influential factors. An Environmental Stressor Index (ESI) is constructed, integrating climatic, hydrological, and land-use dimensions. The ESI is applied to three districts—Rudraprayag, Udham Singh Nagar, and Almora—to assess their vulnerability. The results suggest that Rudraprayag faces high exposure to climate extremes (heatwaves, floods, and droughts) but benefits from a relatively stronger infrastructure. Udham Singh Nagar exhibits the highest overall vulnerability, driven by water stress, air pollution, and salinity, whereas Almora remains relatively less exposed, apart from moderate drought and connectivity stress. Simulations based on RCP 4.5 and RCP 8.5 scenarios indicate increasing stress across all regions, with Udham Singh Nagar consistently identified as the most vulnerable. Rudraprayag experiences increased stress under the RCP 8.5 scenario, while Almora is the least vulnerable, though still at risk from drought and pest outbreaks. By incorporating crop yield models into the ESI framework, this study advances a systems-level tool for assessing agricultural vulnerability to climate change. This research holds global relevance, as food supply chains in climate-sensitive regions such as Africa, Southeast Asia, and Latin America face similar compound stressors. Its novelty lies in integrating a Fuzzy DEMATEL-based Environmental Stressor Index with crop yield modeling. The findings highlight the urgent need for climate-informed food system planning and policies that integrate environmental and social vulnerabilities. Full article

The coastal Oder/Szczecin Lagoon is subject to multiple external changes, particularly the reduction in external nutrient loads and the impacts of climate change, including rising temperatures and more frequent heatwaves. By combining monitoring data covering the past 40 years with 3D ecosystem modelling, we assess changes in phytoplankton abundance and diversity across different temporal scales, ranging from long-term trends to the short-term effects. Despite strong reductions in external nutrient loads, neither the average annual phytoplankton biomass nor the long-term species composition changed significantly, although extreme summer blooms appear to have decreased. In summer, cyanobacteria, usually dominated by Microcystis, can reach a relative biovolume of up to 90%. Bacillariophyceae (diatoms) contribute up to 72% of the annual relative biovolume and dominate in spring. Both interannual and short-term variability in phytoplankton biomass and composition are pronounced. Heat- and coldwaves show no consistent immediate effects; however, results suggest that cyanobacteria, particularly Microcystis, benefit from hot summers. In contrast, diatoms appear less responsive to temperature, although they tend to contribute more in colder years, with distinct shifts in species composition observed between hot and cold springs. Model simulations indicate that a 1.5 °C increase in air temperature would, via elevated water temperatures, raise average monthly phytoplankton biomass by 4% in July and by 9% in August, further promoting cyanobacteria growth. Full article

Internal waves play a critical role in material transport, vertical mixing, and energy dissipation within stratified aquatic systems. Their dynamics are strongly modulated by thermal stratification and surface meteorological forcing. This study examines the influence of interannual meteorological variability from 1980 to 2010 on internal wave behavior using a series of numerical simulations in Lake Biwa in Japan. In each simulation, air temperature, wind speed, or precipitation was perturbed by ±2 standard deviations relative to the climatological mean. Power spectral analysis of simulated velocity fields was conducted for the surface, thermocline, and bottom layers, focusing on super-inertial (6–16 h), near-inertial (~16–30 h), and sub-inertial (>30 h) frequency bands. The results show that higher air temperatures intensify stratification and enhance near-inertial internal waves, particularly within the thermocline, whereas cooler conditions favor sub-inertial wave dominance. Increased wind speeds amplify internal wave energy across all layers, with the strongest effect occurring in the high-frequency band due to intensified wind stress and vertical shear, while weaker winds suppress wave activity. Precipitation variability primarily affects surface stratification, exerting more localized and weaker impacts. These findings highlight the non-linear, depth-dependent responses of internal waves to atmospheric drivers and improve understanding of the coupling between climate variability and internal wave energetics. The insights gained provide a basis for more accurate predictions and sustainable management of stratified aquatic ecosystems under future climate scenarios. Full article

This study investigates the impact of vibration frequency on the performance of a 10-cell open-cathode direct methanol fuel cell (OC-DMFC) stack. Experiments were conducted using three different vibration frequencies (15, 30, and 60 Hz) and compared against a baseline condition without vibration. Performance was evaluated under varying methanol–water fuel flow rates (1, 5, 25, and 50 mL·min⁻¹) while maintaining constant operating conditions: methanol temperature at 70 °C, methanol concentration at 1 M, and cathode air flow velocity at 4.8 m·s⁻¹. The optimal performance was observed at a fuel flow rate of 5 mL·min⁻¹, where the maximum power density reached 26.05 mW·cm⁻² under 15 Hz vibration—representing a 14% increase compared to the non-vibrated condition. These findings demonstrate that low-frequency vibration can enhance fuel cell performance by improving mass transport characteristics. Full article

The urban heat island (UHI) significantly compromises outdoor thermal comfort and public health in hot climates. While urban vegetation is a recognized mitigation strategy, its performance variability across different urban fabrics remains a critical knowledge gap. This research quantitatively evaluates the microclimatic impact of vegetation strategies by comparing two districts with distinct urban morphologies: low-density and high-density. Using the Envi-met software, we simulated a reference case and four vegetation scenarios with constant 50% grass coverage and incrementally increasing tree percentages (0% to 75%). Thermal performance was assessed through key metrics, including air temperature (T_a), relative humidity (RH), mean radiant temperature (T_mrt), and Physiologically Equivalent Temperature (PET). The results reveal that vegetation’s effectiveness is directly correlated with urban density. The most comprehensive strategy (Scenario-D: 50% grass, 75% trees) reduced peak PET by up to 7.5 °C in the low-density El Khazzan, a reduction nearly three times greater than the 2.7 °C achieved in the high-density El Akkad. Similarly, this scenario achieved a maximum daytime T_a reduction of 0.92 K in El Khazzan, compared to only 0.4 K in the high-density district. The study also identifies a critical trade-off: high-density tree scenarios increased nighttime temperatures by up to 0.4 K due to disrupted airflow, whereas the grass-only scenario maintained thermal stability. These findings underscore that a one-size-fits-all approach to urban greening is insufficient. For practical implications, urban planners must abandon generic strategies and integrate a nuanced understanding of local morphology to maximize the thermal benefits of vegetation, particularly in hot, arid environments. Full article

Previous studies have suggested that Earth’s annual cycle of modern climate provides information relevant to orbital-scale climate variability, since both are driven by solar insolation changes determined by orbital geometry. However, there has been no systematic assessment of the climate response to annual-scale insolation changes in climate models, leading to large uncertainty in orbital-scale simulation. In this study, we evaluate the Northern Hemisphere land surface air temperature response to the annual insolation cycle in the Coupled Model Intercomparison Project Phase 6 (CMIP6) models. A polynomial transfer framework reveals that CMIP6 models broadly capture the observed 20–30-day lag between insolation and temperature, indicating realistic land thermal inertia. However, CMIP6 models consistently overestimate temperature sensitivities to insolation, with particularly strong biases over mid-latitude and high-latitude regions in summer and winter, respectively. Applying the annual-scale polynomial transfer framework to the middle Holocene (~6000 years ago) shows that models with the highest sensitivity simulate significantly larger seasonal temperature anomalies than the lowest-sensitivity models, underscoring the impact of modern biases on orbital-scale paleoclimate simulations. The results highlight systematic overestimation of temperature–insolation sensitivity in CMIP6 models, emphasizing the importance of constraining seasonal sensitivity for robust orbital-scale climate modeling. Full article

Coal blending has become a common practice in large-scale boilers due to fluctuations in fuel supply, and it has an important impact on combustion and nitric oxide (NO) formation. To clarify these effects, this study numerically investigates the combustion characteristics and NO generation in a 130 t/h tangentially fired pulverized-coal boiler under boiler maximum continuous rating (BMCR) conditions. A three-dimensional furnace model was developed based on the actual boiler geometry, and combustion was simulated using coal combustion sub-models coupled with the discrete phase model (DPM). The results indicate that increasing the proportion of bituminous coal raises the peak furnace temperature from 1856 K under unblended firing to 1959 K at 80% blending and increases the outlet NO concentration from 357 mg/m³ to 457 mg/m³. Furthermore, coal blending shifts flame intensity toward the furnace wall, enhances carbon monoxide (CO) formation in oxygen-deficient near-wall regions, and promotes NO generation in wall-adjacent high-temperature zones. These findings demonstrate that coal blending significantly influences combustion performance and pollutant emissions, highlighting the need for optimized air distribution and blending strategies in tangentially fired boilers. Full article

Due to the evident increase in tick-borne diseases worldwide, it is necessary to constantly update information on the distribution and zoonotic potential of hard ticks. We studied diversity, population structure, and seasonal dynamics of hard tick fauna, faunal similarity and the climate impact on tick occurrence in natural habitats (NHs) (forest communities) and anthropogenic habitats (AHs) (orchards, grasslands, degraded forests) in eastern and central parts of Continental Croatia. Host-seeking hard ticks were sampled by the flag-dragging method in lowland AHs (Bansko Hill (BH); 2023–2024 yr.) and in mountainous NHs (Medvednica Mountain (MM); 2019–2021, 2024 yr.). Overall, 2726 specimens belonging to eight hard tick species (Ixodes ricinus, I. frontalis, I. hexagonus, I. kaiseri, Haemaphysalis inermis, H. concinna, Dermacentor marginatus, D. reticulatus) were identified in AHs, while in NHs 1543 hard ticks, belonging to three species (I. ricinus, I. frontalis, D. reticulatus), were collected. The most abundant species in both habitat types (47.83% in AHs, 99.80% in NHs) was I. ricinus, showing unimodal seasonal activity within studied NHs and bimodal activity at AHs. Comparison of hard tick fauna in different habitats using the Sørenson index on BH and MM showed a high percentage of similarity (50.0–88.8). At AHs, a significant (p < 0.05) negative correlation was determined between the abundance (N) and the mean monthly air temperatures (°C) for H. inermis (r = −0.5931; p = 0.0421) and D. reticulatus (r = −0.6289; p = 0.0285), while their numbers positively correlated (r = 0.5551; p = −0.2667; r = 0.4430; p = 0.1492) with air humidity (%). In contrast, the number of sampled host-seeking I. ricinus ticks at natural forest habitats on MM was positively associated with air temperature and negatively with air humidity at elevations from 200 to 1000 m a.s.l. (r = −0.7684; p = 0.0259; at 200 m a.s.l.). Collected specimens of I. frontalis mark the first record for Osijek–Baranja County, while the sampled D. reticulatus on MM represents the first catch at 1000 m a.s.l. in Croatia. This new data on the distribution and seasonality of medically important hard tick species in Continental Croatia contributes to identifying tick-risk foci and high-risk periods. Full article

In steel continuous casting, the secondary cooling zone is usually equipped with air-mist nozzles. Spray nozzle clogging is a common problem that reduces cooling efficiency and affects product quality. This study uses a 3D CFD model to investigate its impact on heat transfer. The model includes the full-size caster geometry and actual nozzle layout to analyze the effect of clogging on the cooling process. The solidification process is modeled using the enthalpy-porosity method. Spray cooling is defined through empirical HTC correlations on the slab surface. The study focuses on how nozzle clogging changes the surface temperature, cooling rate, and metallurgical length (ML). Simulation results show that clogging raises the local surface temperature by about 100 K and increases the ML. More clogged nozzles lead to a longer ML. Clogging near the meniscus has a stronger impact, showing that early-stage cooling plays an important role in solidification. Even a single clogged nozzle can increase the ML by 3.2%, highlighting the significant effect of nozzle clogging on the casting process. Full article

Evaporation Duct Height (EDH) is a crucial parameter in evaporation duct modeling, as it directly influences the strength of the waveguide trapping effect and significantly impacts the over-the-horizon detection performance of maritime radars. To address the limitations of low prediction accuracy and limited interpretability in existing deep learning models under complex marine meteorological conditions, this study proposes a surrogate model, BLA-EDH, designed to emulate the output of the Naval Postgraduate School (NPS) model for real-time EDH estimation. Experimental results demonstrate that BLA-EDH can effectively replace the traditional NPS model for real-time EDH prediction, achieving higher accuracy than Multilayer Perceptron (MLP) and Long Short-Term Memory (LSTM) models. Random Forest analysis identifies relative humidity (0.2966), wind speed (0.2786), and 2-m air temperature (0.2409) as the most influential environmental variables, with importance scores exceeding those of other factors. Validation using the parabolic equation shows that BLA-EDH attains excellent fitting performance, with coefficients of determination reaching 0.9999 and 0.9997 in the vertical and horizontal dimensions, respectively. This research provides a robust foundation for modeling radio wave propagation in the Yellow Sea and Bohai Sea regions and offers valuable insights for the development of marine communication and radar detection systems. Full article

Indoor sports facilities present unique challenges for air quality management due to high crowd densities and limited ventilation. This study investigated air quality in a municipal athletic facility in Komotini, Greece, focusing on concentrations of airborne particulate matter (PM_1.0, PM_2.5, PM₁₀), humidity, and temperature across spectator zones, under varying mask scenarios. Sensing devices were installed in the stands to collect high-frequency environmental data. The system, based on optical particle counters and cloud-enabled analytics, enabled real-time data capture and retrospective analysis. The main experiment investigated the impact of spectators wearing medical masks during two basketball games. The results show consistently elevated PM levels during games, often exceeding recommended international thresholds in the spectator area. Notably, the use of masks by spectators led to measurable reductions in PM_1.0 and PM_2.5 concentrations, because they seem to have limited the release of human-generated aerosols as well as the amount of movement among spectators, supporting their effectiveness in limiting fine particulate exposure in inadequately ventilated environments. Humidity emerged as a reliable indicator of occupancy and potential high-risk periods, making it a valuable parameter for real-time monitoring. The findings underscore the urgent need for improved ventilation strategies in small to medium-sized indoor sports facilities and support the deployment of low-cost sensor networks for actionable environmental health management. Full article

Indoor environmental quality in offices, comprising thermal, acoustic, lighting, and air quality domains, is known to influence human comfort, yet the relative importance of their sub-factors—particularly in severe cold regions—remains unclear. This study addresses this gap by integrating objective (Criteria Importance Through Intercriteria Correlation, CRITIC) and subjective (Analytic Hierarchy Process, AHP) weighting methods, supported by field measurements and questionnaire surveys in open-plan offices in three provinces in northeastern China. Cluster analysis categorized acoustic sub-factors into outdoor traffic, outdoor entertainment, people conversation, burst sound, and people movement. Results show that temperature is the dominant thermal comfort driver (39.7% CRITIC; 45.5% AHP), exceeding air velocity and humidity, which had nearly equal influence. Indoor sound exerted greater impact than outdoor sound, with people conversation ranked highest among indoor noise sources, and burst sound and movement showing similar but slightly lower weights. Natural light outweighed artificial light in importance (54.2% CRITIC; 61.0% AHP), while air freshness and pollution were nearly equally influential. Compared to CRITIC, AHP produced more dispersed weights, reflecting subjective bias toward pronounced differences. These findings provide a quantitative basis for prioritizing environmental design interventions—such as controlling indoor conversational noise, optimizing natural lighting, and stabilizing temperature—to enhance comfort in offices in severe cold regions. Full article

This preliminary study investigates the optimization of the mechanical properties of the zinc wrought alloy ZEP1510 with the objective of assessing its potential to approach the hardness, strength, and toughness of the brass alloy, CuZn21Si3P. Enhancing both toughness and hardness was targeted to improve the durability of potential replacement components. Heat treatment was the primary method, applying annealing, air cooling, water quenching, and artificial aging to modify material properties. Mechanical characterization was performed through Brinell hardness, as well as tensile and Charpy impact testing, complemented by metallographic analysis. Air cooling from temperatures near the transformation point at 275 °C produced a visually refined and homogeneous microstructure (qualitative assessment by OM/SEM), resulting in simultaneous increases in hardness and toughness. Water quenching from this range yielded a metastable state with high toughness but low hardness, while subsequent natural aging significantly increased strength and reduced toughness. Artificial aging indicated precipitation hardening behavior similar to that of aluminum alloys. Although property improvements were achieved, the targeted combination of high toughness and high strength was not fully realized. The findings suggest that controlled artificial aging, alternative quenching media and grain refinement strategies could further enhance performance, providing a basis for tailoring ZEP1510 for demanding engineering applications. Full article

Global warming has been altering the East Asian climate at an unprecedented rate since the 20th century. In order to evaluate the changes in the East Asian winter climate (EAWC) and support policy-making for climate mitigation and adaptation strategies, this paper utilizes the multimodel ensemble from the Couple Model Intercomparison Project 6 and a temperature threshold method to investigate the EAWC changes during the period 1979–2100. The results show that the EAWC has been undergoing widespread and robust changes in response to global warming. The winter length in East Asia has shortened and will continue shortening owing to later onsets and earlier withdrawals, leading to a drastic contraction in length from 100 days in 1979 to 43 days (27 days) in 2100 under SSP2-4.5 (SSP5-8.5). While most regions of the East Asian continent are projected to become warmer in winter, the Japan and marginal seas of northeastern Asia will face the risks from colder winters with more frequent extreme cold events, accompanied by less precipitation. Meanwhile, the Tibetan Plateau is very likely to have colder winters in the future, though its surface snow amounts will significantly decline. Greenhouse gas (GHG) emissions are found to be responsible for the EAWC changes. GHG traps heat inside the Earth’s atmosphere and notably increases the air temperature; moreover, its force modulates large-scale atmospheric circulation, facilitating an enhanced and northward-positioned Aleutian low together with a weakened Siberian high, East Asian trough, and East Asian jet stream. These two effects work together, resulting in a contracted winter with robust and uneven regional changes in the EAWC. This finding highlights the urgency of curbing GHG emissions and improving forecasts of the EAWC, which are crucial for mitigating their major ecological and social impacts. Full article