Search Results (2,882)

High-entropy materials have emerged as promising candidates for high-temperature structural, magnetic, and electrochemical applications due to their unique combination of compositional complexity, thermal stability, and tailored functionality. In this study, self-propagating high-temperature synthesis (SHS) was employed to fabricate high-entropy composite in a Ti–Cr–Mn–Co–Ni–Al–C multicomponent system with a focus on elucidating the effect of titanium content on the combustion parameters, as well as on the phase and structure formation patterns of the resulting materials. In situ profiling enables evaluating the maximum combustion temperature of 1560 °C, combustion wave propagation velocity ranging from 0.22 to 4.3 mm/s depending on titanium content, and heating and cooling rates of 300–2000 °C/s and 3 °C/s during synthesis. The synthesized powders exhibited a bimodal particle size distribution, with ~90% of particles below 25 μm and a D50 of 5.38 μm. Post-synthesis densification via spark plasma sintering (SPS) at 1250 °C under 45 MPa yielded dense bulk samples, which exhibited a high relative density and high Vickers microhardness of 1270 ± 35 HV10 attributed to fine TiC dispersion and secondary carbide formation. Thermogravimetric analysis performed under air flow with a heating rate of 20 °C/min showed enhanced thermal stability for both the powder and the sintered bulk. These findings demonstrate the efficacy of SHS for rapid, energy-efficient fabrication of high-entropy composites and underscore the critical role of composition in tailoring their structural and mechanical properties. Full article

Hydrogen-rich gas (HRG) injection is a promising low-carbon solution for blast furnace ironmaking. This study conducted numerical simulations in the lower part of a blast furnace to analyze the combustion behavior of coinjected coke oven gas (COG) and pulverized coal (PC) within the raceway and the associated thermal load on the tuyere. A three-dimensional computational fluid dynamics model incorporating fluid–thermal–solid coupling and the GRI-Mech 3.0 chemical kinetic mechanism (validated for 300–2500 K) was established to simulate the lance–blowpipe–tuyere–raceway region. The simulation results revealed that moderate COG injection accelerated volatile release from PC and enlarged the high-temperature zone (>2000 K). However, excessive COG injection intensified oxygen competition and shortened the residence time of PC, ultimately decreasing the burnout rate. Notably, although COG has high reactivity, its injection did not cause an increase in tuyere temperature. By contrast, the presence of an unburned gas layer near the upper wall of the tuyere and the existence of a strong convective cooling effect contributed to a reduction in tuyere temperature. An optimized cooling water channel was designed to enhance flow distribution and effectively suppress localized overheating. The findings of this study offer valuable technical insights for ensuring safe COG injection and advancing low-carbon steelmaking practices. Full article

This study examines the thermal performance of phase change material (PCM)–metal foam composites under base heating, a configuration more relevant to compact thermal energy storage (TES) and electronics-cooling applications, compared to the widely studied side-heated case. Metal foams with pore densities of 10, 20, and 40 PPI, but identical porosity (volumetric value), were impregnated with two PCMs (paraffin RT55 and RT64HC) and tested under varying heat fluxes. The thermophysical properties of three PCMs (RT42, RT55, and RT64HC) were first characterized using the T-history method. A control case consisting of pure PCM revealed significant thermal lag between the heater and the PCM, whereas the inclusion of a metal foam improved temperature uniformity and accelerated melting. The results showed that PPI variation had little influence on melting completion time, while PCM type, viz., melting temperature, strongly affected duration. Heat flux was the dominant parameter: higher input power substantially reduced melting times, although diminishing returns were observed at elevated heat fluxes. An empirical correlation from the literature, originally developed for side-heated foams, was applied to the base-heated configuration and reproduced the main melting trends, though it consistently underpredicted completion times at high fluxes. Overall, embedding PCMs in metal foams enhances heat transfer, mitigates localized overheating, and enables more compact and efficient TES systems. Future work should focus on developing correlations for non-adiabatic cases, exploring advanced foam architecture, and scaling the approach for practical energy storage and cooling applications. Full article

Two prototype moss-based green roof systems were developed and evaluated using a newly cultivated strain of Racomitrium japonicum (Dozy & Molk.) to investigate their feasibility in mitigating rooftop heat and enhancing carbon sequestration under actual urban conditions. Flat and sloped-type green roof systems (2 m × 2 m each) were developed and installed on a rooftop to investigate their performance in summer (from June to August 2025). The moss-based systems reduced rooftop surface temperature by an average of 6–10 °C during daytime and retained approximately 1.5–2.5 °C of heat at night, thereby contributing to cooling and thermal buffering. The moss layer effectively reduced solar radiation heating of the underlying soil. Despite exposure to intense sunlight and high summer temperatures, the moss maintained a consistent growth rate of 3–5 mm per month. The annual carbon sequestration capacity of the prototype system was estimated at approximately 0.3 kg C/m².year, which is comparable to values reported for other vegetation types. These findings indicate that moss-based green roofs incorporating the newly cultivated moss strain have practical potential for urban heat island mitigation and carbon capture. Full article

Amid long-term human consumption of surface resources and the intensifying climate crisis, underground space has increasingly attracted attention as a viable alternative for habitation, survival, and urban resilience. Historical and contemporary examples—from the Derinkuyu Underground City in Cappadocia, Turkey, to Iran’s “Shavadan” cooling system, as well as subterranean dwellings in hot arid regions such as the Berbers’ homes in Tunisia and miners’ settlements in Coober Pedy, Australia, and underground complexes in cold regions like Harbin, Sapporo, and Helsinki—demonstrate the significant advantages of underground spaces in thermal regulation, protection from extreme weather, and efficient resource utilization. With climate change driving increasingly frequent and severe extreme weather events, including tornadoes, typhoons, and prolonged droughts, surface buildings face growing vulnerability, further emphasizing the potential of underground space for sustainable urban development. In parallel, advances in science and technology, particularly in space exploration, have accumulated extensive practical knowledge, creating pathways to extend terrestrial construction experience into extraterrestrial environments. The Moon, despite its strategic significance and potential resource value, presents an extremely hostile surface environment characterized by microgravity, near-vacuum conditions, extreme diurnal temperature variations of several hundred degrees, and very low thermal conductivity, all of which render conventional surface habitation challenging and prohibitively costly. Consequently, contemporary research has gradually shifted focus from lunar surface facilities toward the development and utilization of lunar underground spaces, which could provide enhanced environmental stability and habitation potential. This paper reviews the historical development and current research on lunar underground space utilization, proposes five guiding principles for its progressive exploration and construction, and presents a phased “1.0–4.0 era” framework for systematic development. Additionally, based on an adaptive design theoretical framework, spatial, environmental, and climatic strategies are proposed to guide future lunar habitation and ensure sustainable extraterrestrial development, providing a comprehensive reference for long-term planning and construction of lunar underground habitats. Full article

Floating and offshore photovoltaic (FPV) installations present a promising solution for addressing land-use conflicts while enhancing renewable energy production. With an estimated global offshore PV potential of 4000 GW, FPV systems offer unique advantages, such as increased efficiency due to water cooling effects and synergy with other offshore technologies. However, challenges related to installation costs, durability, environmental impacts, and regulatory gaps remain. This review provides a comprehensive and critical analysis of FPV advancements, focusing on inland, nearshore, and offshore applications. A systematic evaluation of recent studies is conducted to assess technological innovations, including material improvements, mooring strategies, and integration with hybrid energy systems. Furthermore, the economic feasibility of FPVs is analysed, highlighting cost–benefit trade-offs, financing strategies, and policy frameworks necessary for large-scale deployment. Environmental concerns, such as biofouling, wave-induced stress, and impacts on aquatic ecosystems, are also examined. The findings indicate that while FPV technology has demonstrated significant potential in enhancing solar energy yield and water conservation, its scalability is hindered by high capital costs and the absence of standardised regulations. Future research should focus on developing robust offshore floating photovoltaic (OFPV) designs, optimising material durability, and establishing regulatory guidelines to facilitate widespread adoption. By addressing these challenges, FPVs can play a critical role in achieving global climate goals and accelerating the transition to sustainable energy systems. Full article

Efficient management of heat transfer and entropy generation in nanofluid enclosures is essential for the development of high-performance thermal systems. This study employs the finite element method (FEM) to numerically analyze the effects of wall corrugation and base inclination on magnetohydrodynamic (MHD)-assisted natural convection of Cu–H₂O nanofluid in a trapezoidal cavity containing internal heat-generating obstacles. The governing equations for fluid flow, heat transfer, and entropy generation are solved for a wide range of Rayleigh numbers (10³–10⁶), Hartmann numbers (0–50), and geometric configurations. Results show that for square obstacles, the Nusselt number increases from 0.8417 to 0.8457 as the corrugation amplitude rises (a = 0.025 L–0.065 L) at Ra = 10³, while the maximum heat transfer (Nu = 6.46) occurs at Ra = 10⁶. Entropy generation slightly increases with amplitude (15.46–15.53) but decreases under stronger magnetic fields due to Lorentz damping. Higher corrugation frequencies (f = 9.5) further enhance convection, producing Nu ≈ 6.44–6.47 for square and triangular obstacles. Base inclination significantly influences performance: γ = 10° yields maximum heat transfer (Nu ≈ 6.76), while γ = 20° minimizes entropy (St ≈ 0.00139). These findings confirm that optimized corrugation and inclination, particularly with square obstacles, can effectively enhance convective transport while minimizing irreversibility, providing practical insights for the design of energy-efficient MHD-assisted heat exchangers and cooling systems. Full article

Generalized frosts have a significant impact on the Pampa Húmeda of Argentina, particularly those without persistence (0DP), defined as events that do not last more than one day, and are the most frequent generalized frosts. This study investigates the dynamical and physical mechanisms that sustain these events, emphasizing the nonlinear interactions represented by the Rossby Wave Source (RWS) equation. Composite analysis of pressure, temperature, wind and geopotential height fields were performed, showing that 0DP events are related to abrupt cold air intrusion linked to the enhancement of upper levels troughs over the eastern Pacific Ocean and transient surface anticyclones over South America. This linear analysis only showed a lack of persistent upper-level maintenance and did not explain the dynamics of the rapid weakening of the circulation. For this reason, a nonlinear analysis based on the decomposition of the RWS equation into its advective and divergent terms is performed. The advective term only acts as an initial trigger, deepening troughs and favoring meridional cold air advection, while the divergent term dominates the events, representing 63–67% of the affected area. This term reinforces ridges, promotes subsidence and favors clear sky conditions that enhance nocturnal radiative cooling and frost formation. Positive anomalies of the divergent RWS term strengthen the ridge and advect cold air over the Pampa Húmeda, whereas subsequent negative anomalies over the southwestern Atlantic act as sinks of wave activity, leading to the rapid dissipation of the synoptic configuration. Consequently, the same mechanism that generates favorable conditions for frost development also determines their lack of persistence. These findings demonstrate that the short-lived nature of 0DP frosts is not due to the absence of dynamical forcing, but rather to nonlinear processes that both enable and constrain frost occurrence. This highlights the importance of incorporating nonlinear diagnostics, such as the RWS, to improve the understanding of short-lived atmospheric extremes. Full article

Biomass has long been a major source of energy for residential heating and, in recent decades, has regained attention as a renewable alternative to fossil fuels. This review explores the current state and prospects of domestic biomass-based heating technologies, including biomass-fired boilers, local space heaters, and hybrid systems that integrate biomass with complementary renewable energy sources to deliver heat, electricity, and cooling. The review was conducted to identify key trends, performance data, and innovations in conversion technologies, fuel types, and efficiency enhancement strategies. The analysis highlights that biomass is increasingly recognized as a viable energy carrier for energy-efficient, passive, and nearly zero-energy buildings, particularly in cold climates where heating demand remains high. The analysis of the available studies shows that modern biomass-fired systems can achieve high energy performance while reducing environmental impact through advanced combustion control, optimized heat recovery, and integration with low-temperature heating networks. Overall, the findings demonstrate that biomass-based technologies, when designed and sourced efficiently and sustainably, can play a significant role in decarbonizing the residential heating sector and advancing nearly zero-energy building concepts. Full article

This study investigates the thermal resilience of naturally ventilated Lebanese residential buildings in the context of future climates, based on four climate zones: coastal (moderate and humid), low mountain (cool and seasonally variable), inland plateau (semi-arid with high summer heat), and high mountain (cold, with significant winter conditions). The aim of the study is to evaluate how passive envelope interventions can enhance indoor thermal resilience under five present and future work scenarios: TMY, SSP1-2.6 (2050 and 2080), and SSP5-8.5 (2050 and 2080). A baseline model was developed for typical building stock in each climate using EnergyPlus-23.2.0. The passive design parameters of window type, shading depth, and building orientation were systematically altered to analyze their effect on thermal comfort and building thermal resilience. Unlike previous studies that assessed either individual passive strategies or a single climate condition, this research combines multi-objective optimizations with overheating resilience metrics, by optimizing passive interventions using the GenOpt-3.1.0 and BESOS (Python-3.7.3 packages to minimize indoor overheating degree (IOD) and maximize climate change overheating resistivity (CCOR) index. Our findings indicate that optimized passive interventions, such as deep shading (0.6–1.0 m), low-e or bronze glazing, and southern orientations, can reduce overheating in all climate zones, reflecting a substantial improvement in thermal resilience. The novelty of this work lies in combining passive envelope optimization with future climate situations and a long-term overheating resilience index (CCOR) in the Mediterranean region. The results provide actionable suggestions for enhancing buildings’ resilience to climate change in Lebanon, thus informing sustainable design practice within the Eastern Mediterranean climate. Full article

Wire Arc Additive Manufacturing (WAAM) enables cost-effective fabrication of complex metallic components but faces challenges in achieving consistent tensile strength for cylindrical parts with intricate internal features (e.g., cooling channels, helical grooves), where conventional machining is often infeasible or prohibitively expensive. This study introduces a novel stacked ring substrate strategy with pre-formed low-carbon steel rings defining complex internal geometries, followed by external WAAM deposition using ER70S-6 wire to overcome these limitations. Five process parameters (welding current: 110–130 A; offset distance: 2.5–3.0 mm; Step Length: rotary to straight; torch speed: 400–500 mm/min; weld thickness: 2.0–3.0 mm) were optimized using a Taguchi L25 orthogonal array (25 runs in triplicate). ANOVA identified Step Length as the dominant factor, with straight paths significantly reducing thermal cycling and improving interlayer bonding, alongside a notable current × speed interaction. Optimal settings achieved tensile strengths of 280–290 MPa, significantly below wrought ER70S-6 benchmarks (400–550 MPa) due to interfacial weaknesses at ring fusion zones and thermal accumulation from stacked cylindrical geometry, a limitation acknowledged in the absence of microstructural or thermal history data. A Random Forest Regressor predicted strength with R² = 0.9312, outperforming conventional models. This hybrid approach significantly enhances design freedom and mechanical reliability for high-value cylindrical components in aerospace and tooling, establishing a scalable, data-driven framework for geometry-constrained WAAM optimization. Full article

Sustainable mine geothermal energy causes high-temperature hazards in mine roadways, severely endangering miners’ lives. There is an urgent need to enhance research on the performance of composite phase change material (CPCM) roadway cooling systems, as they can effectively control ambient temperatures. However, existing research on CPCM roadway cooling system performance remains limited. This study innovatively establishes a numerical model for a novel cascade CPCM roadway cooling system and employs the control variable method to investigate the influence of multi-parameter regulation on system performance. The study reveals that the ring pipe radius ratio significantly impacts the system’s heat exchange efficiency and temperature distribution. The optimal comprehensive system performance is achieved at an annular tube radius ratio of 2:3, where the CPCM solid phase percentage for 89.03% and the average temperature of the monitoring surface decreases by 9.54 °C. Increasing the cascaded tube spacing enhances the overall cooling effect, but cooling efficiency diminishes when the spacing exceeds 0.5 m. The CPCM phase change temperature must align with the mine’s geothermal conditions, with CPCM utilization and cooling efficiency peaking at 25 °C. The air deflector structure effectively mitigates cooling lag in the lower roadway section. At an installation angle of 30°, the expansion distance of the lower low-temperature zone increased by up to 48.89% without compromising cooling efficiency in the upper roadway section, while also delaying the recovery rate of heat damage. Full article

The cooling effect from the para-ortho hydrogen conversion (POC) combined with a vapor-cooled shield (VCS) and multi-layer insulation (MLI) can effectively extend the storage duration of liquid hydrogen in cryogenic tanks. However, there is currently no effective and straightforward empirical correlation available for predicting the catalytic POC efficiency in VCS pipelines. This study focuses on the development of correlations for the catalytic conversion of para-hydrogen to ortho-hydrogen in pipelines, particularly in the context of cryogenic hydrogen storage systems. A model that incorporates the Langmuir adsorption characteristics of catalysts and introduces the concept of conversion efficiency to quantify the catalytic process’s performance is introduced. Experimental data were obtained in the temperature range of 141.9~229.9 K from a cryogenic hydrogen catalytic conversion facility, where the effects of temperature, pressure, and flow rate on the catalytic conversion efficiency were analyzed. Based on a validation against the experimental data, the proposed model offers a reliable method for predicting the cooling effects and optimizing the catalytic conversion process in VCS pipelines, which may contribute to the improvement of liquid hydrogen storage systems, enhancing both the efficiency and duration of storage. Full article

Aircraft cargo compartment fires represent a major threat to aviation safety due to their rapid development, concealment, and the challenges associated with suppression in confined spaces. This study analyzes the 2019 A330 cargo compartment fire at Beijing Capital International Airport as a representative case. Based on flight crew statements, ECAM alerts, surveillance footage, and firefighting records, the event timeline was reconstructed and the emergency response process examined. The analysis identified four defining characteristics of cargo fires: rapid escalation, interacting hazards, restricted accessibility, and prolonged suppression duration. To address these challenges, a three-stage investigation framework—comprising timeline reconstruction, evidence analysis, and experimental verification—is proposed to systematically determine the causes of fires. In addition, a portable penetrating fire-suppression device was designed and experimentally validated. Results confirm its effectiveness in achieving rapid agent delivery, enhanced structural cooling, and prevention of re-ignition. The findings demonstrate that comprehensive cargo fire investigations require the integration of multi-source data and experimental validation, while tactical and equipment innovations are critical for improving suppression efficiency in confined environments. This research provides practical insights for optimizing cargo fire investigation methodologies and emergency response strategies, thereby contributing to the advancement of aviation safety management systems. Full article

Dynamical downscaling is an essential approach for bridging the gap between coarse-resolution global climate models and regional details required for climate impact assessment and sustainable development planning. Thailand, a climate-sensitive country in Southeast Asia, requires robust climate information to support its adaptation and resilience strategies. This study evaluated the Weather Research and Forecasting (WRF) model in dynamically downscaling selected Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations over Thailand during the baseline period of 1976–2005. A two-way nested WRF configuration was employed, with domains covering Southeast Asia (36 km) and Thailand (12 km) in the model. Model outputs were compared with gridded observations from the Climatic Research Unit (CRU TS), and spatial variations were analyzed across six administrative regions in Thailand. The WRF successfully reproduces broad climatological patterns, including the precipitation contrast between mountainous and lowland areas and the north–south gradient of temperature. Seasonal cycles of rainfall and temperature are generally well represented, although systematic biases remain, specifically the overestimation of orographic rainfall and a cold bias in high-elevation regions. The 12 km WRF simulations demonstrated improved special and temporal agreement with the CRU TS dataset, showing a national-scale wet bias (MBE = +17.14 mm/month), especially during the summer monsoon (+65.22 mm/month). Temperature simulations exhibited seasonal derivations, with a warm bias in the pre-monsoon season and a cold bias during the cool season, resulting in annual cold biases in both maximum (−1.25 C) and minimum (−0.80 C) temperatures. Despite systematic biases, WRF-CMIP5 downscaled framework provides enhanced regional climate information and valuable insights to support national-to-local climate change adaptation, resilience planning, and sustainable development strategies in Thailand and the broader Southeast Asian region. Full article