Search Results (13,026)

Efficient thermal management of lithium-ion batteries is critical for the safety, performance, and longevity of electric vehicles. This work numerically investigates a battery thermal management system (BTMS) for a LiFePO₄ battery, featuring a liquid-cooling plate with novel droplet-shaped turbulators and coolant with different nanofluids. Computational Fluid Dynamics (CFD) simulations were employed to analyze the effects of cooling channel geometry, nanofluid type, nanoparticle volume fraction, coolant inlet velocity, and battery discharge rate on the system’s thermal performance and pressure drop. Results show that the droplet-shaped channel reduces the maximum battery temperature by 1.64 K compared to a conventional straight channel, owing to enhanced turbulence and larger heat-transfer area. Among different coolants, the 6% Cu–water nanofluid demonstrated the highest cooling effectiveness due to its superior thermal conductivity. To balance competing objectives, a multi-objective optimization using Response Surface Methodology (RSM) and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) was performed. The optimal design was achieved with a coolant velocity of 0.097 m/s and a volume fraction of Cu nanoparticle of 3.85%, which maintained the maximum battery temperature of 299.7 K with a minimal pressure drop of 26.27 Pa at a 1.03 C discharge rate. These findings highlight that a BTMS combining droplet-shaped turbulators with a Cu–water nanofluid provides a highly effective and energy-efficient thermal management strategy. Full article

Urban trees are increasingly deployed as nature-based infrastructure to mitigate heat and manage stormwater, yet quantitative guidance on how species traits and site context shape transpiration remains fragmented. We conducted a systematic metadata analysis of seven field studies that measured daily transpiration rate in urban settings using heat-pulse methods. The units and spatial scales reported were harmonized with the sap flow density across active sapwood (J_s, g H₂O/${\mathrm{cm}}^2$/day) by converting reported stand transpiration and the outer 2 cm of sapwood sap flux using established Gaussian radial distribution functions for angiosperms and gymnosperms, which account for the non-linear decline in sap flux from the vascular cambium to the heartwood boundary. We then summarized distributions and tested group differences with Kruskal–Wallis and Dunn post hoc comparisons across wood anatomy, climate, soil texture, and planting configuration. Conifers exhibited significantly lower median $J_s$ (39.76 g/${\mathrm{cm}}^2$/day) than angiosperms, while the ring-porous group (median $J_s$ = 92.25 g/${\mathrm{cm}}^2$/day) and diffuse-porous groups (median $J_s$ = 96.70 g/${\mathrm{cm}}^2$/day) had similar distributions overall. Climate-modulated responses within wood anatomy groups differed, with diffuse-porous species exhibiting the highest median $J_s$ (152.59 g/${\mathrm{cm}}^2$/day) in semi-arid regions, ring-porous species maintaining comparatively stable median $J_s$ across climates (varying slightly between 80.72 and 99.32 g/${\mathrm{cm}}^2$/day), and conifers reaching their highest median $J_s$ (69.90 g/${\mathrm{cm}}^2$/day) in humid continental sites. Soil texture effects were consistent with moisture availability: sandy loam generally reduced $J_s$ relative to loam or silt loam for conifers and diffuse-porous species. Across anatomies, single trees transpired more than clustered trees or closed canopies. For example, planting as single trees increased median $J_s$ by 86% in conifers (from 33.01 to 61.37 g/${\mathrm{cm}}^2$/day) and by 45% in diffuse-porous species (from 81.31 to 118.25 g/${\mathrm{cm}}^2$/day). These results provide actionable ranges and contrasts to inform species selection and planting design for urban greening and runoff reduction, while highlighting data gaps for future research. Ultimately, by matching specific wood anatomies and planting configurations to local soil and climatic conditions, urban planners and ecohydrologists can strategically optimize urban forests to maximize targeted ecosystem services. Full article

This study conducts multi-scale numerical simulations spanning atomic to macroscopic scales (i.e., from nanometer to millimeter scale) to investigate the fatigue crack propagation behavior in the welded heat-affected zone (HAZ) of AH36 shipbuilding steel. A coupled molecular dynamics–finite element method (MD-FEM) was employed to establish a multi-scale model. Through the transfer of boundary displacements, equivalent mapping of crack morphology, and crack-tip tracking, an iterative multi-scale simulation of 600 tension–tension fatigue cycles was achieved. The results indicate that the crack propagation rate is significantly influenced by crack tip morphology (blunting/sharpening) and growth direction. Notably, the peak strain at the boundary is not the sole determining factor. Periodic blunting of the crack tip occurs during cyclic loading, accompanied by a decrease in the propagation rate. Additionally, the stress field near the crack tip induces microscopic defects such as voids in the nearby area, affecting the crack propagation. This study, based on multi-scale analysis, reveals the microscopic mechanism and evolution law of fatigue crack propagation in the heat-affected zone of AH36 steel welds. Full article

Extreme heat is a major weather-related cause of death and is expected to intensify in European cities. We quantified Milan-specific temperature–mortality relationships, defined impact-based heat thresholds around the minimum mortality temperature (MMT) and identified vulnerable subgroups using individual-level risk factors. We conducted a time-stratified case-crossover study including 2230 natural deaths among Milan residents aged ≥75 years occurring between 15 July and 15 September 2022. The MMT (29 °C) was used as the reference temperature [odds ratio (OR) = 1], and mortality risks were evaluated across high-impact (1.20 < OR ≤ 1.50, ≥35 °C) maximum temperature (Tmax) days. Compared with MMT days, mortality was higher on high-impact days (OR 1.44), with somewhat larger estimates among adults aged ≥85 years (OR 1.63) and men (OR 1.50). Disability (OR 1.51) and socioeconomic deprivation (OR 1.89) were also associated with higher vulnerability, with relatively higher estimates observed in women aged ≥85 years and in men with comorbidities or living alone. Overall, the findings suggest that extreme heat may have had a greater impact on the oldest old and on socially or clinically vulnerable groups, highlighting the possible relevance of targeted heat–health interventions and neighborhood-focused prevention strategies. Full article

Glass preheating prior to laser scanning is expected to enhance internal modification morphology; however, its effect on weld seam topology and welding strength have not been investigated. In the current work, the effects of preheating on ultrafast laser (184 fs and 10 ps) internal modification and welding strength of borosilicate glass slides are investigated. For the internal modification experiments, pulse energy of 30–100 µJ and repetition rate of 10 kHz are used by focusing a laser beam at the interface of optically contacted slides at room temperature (RT ≈ 23 °C), 150 and 200 °C. Welding is conducted by a pulse energy of 4.5–18 µJ and repetition rate of 200 kHz using pre-clamped glass slides with a scanning speed of 10 mm/s at RT and 150 °C. Also, for welding, the optimum number of scans and hatching spacing are identified. Filamentation experiments show that discoloration is not significant when preheat temperature reaches 200 °C. Compared to 10 ps, pulse duration of 184 fs can produce a 19% narrower plasma-modified region at both RT and 150 °C and a 13% wider heat-affected zone at 150 °C. Welding using optimum conditions of 5 scans and 200 µm hatch, and “crack-free” laser parameters produces an average strength of: 50 ± 3.2 MPa at RT and 40 ± 2 MPa at 150 °C for 184 fs compared to 35 MPa at RT and 32 MPa at 150 °C for 10 ps, using 10 replicates each. However, the welding strength upon preheating to 150 °C using 184 fs is still 25% higher compared to average reported laser welding bonding strength, while the 10 ps strength is within the reported average. The enhanced welding strength for 184 fs can be attributed to reduced microcracking, especially when “crack free” combinations are utilized. Full article

In spite of the importance of a detailed description of the filamentary current constriction of the IGBT during the turn-off operation that could lead to the device’s failure, there are to date no quantitative 3D simulation results of the filament growth and dynamic that can be compared with experimental results. In this paper we present 3D numerical simulations on the failure mode in the Unclamped Inductance Switching (UIS) test operation, extended to the full device area, which will be usefully compared with detailed experimental results on a large number of trench IGBT test samples. For the first time extended 3D dynamic electrothermal simulations of the whole die are made, to take into account both the electric and thermal effects of the filamentary conduction in avalanche mode. The onset of a filament growth condition for a current level just above the turnover voltage evaluated by the 3D simulations, and the area of the filament, obtained for the first time, are well in agreement with the quantitative data extracted by the experimental evaluations. Moreover, the thermal heating due to the filament formation is found to be quite independent from the current level, because it depends on the current density in the filament, rather than on the injected current. The delay time between the filament formation and the final failure time seen in the experimental results is verified to be due to the movement of the filament all around the chip surface in search of a cooler spot. The movement of the filament along the whole die area is verified for the first time by full area 3D electrothermal dynamic simulations, with times in agreement with the experimental delay between filament formation and final failure seen in all the failure reports. Full article

Iron-based shape memory alloy (Fe-SMA) fibers can enhance cementitious composites through both crack bridging and thermally activated recovery stresses. Since fiber pull-out governs load transfer at the micro scale, understanding the combined effects of fiber geometry, inclination, and thermal treatment is essential. This study experimentally investigated the pull-out behavior of hooked-end Fe-SMA fibers embedded in high-performance concrete (HPC). A total of 54 ASTM C307-type briquette specimens were tested using single-hook (3D) and double-hook (4D) fibers at inclination angles of 60°, 75°, and 90° under ambient, 100 °C, and 200 °C conditions. Additional flexural, compressive, and direct tensile tests were conducted on plain HPC exposed to the same thermal regime. At ambient temperature, 4D fibers showed 50–70% higher peak pull-out forces than 3D fibers. Heating to 100 °C further increased pull-out resistance by about 6–17%, and the 4D-60-100 configuration achieved the highest performance. In contrast, exposure to 200 °C reduced pull-out resistance by about 5–12% below ambient values. Overall, a 60° inclination generally provided a better response, while 90° produced the lowest. The results confirm that moderate thermal activation combined with double-hook geometry is the most effective strategy for maximizing Fe-SMA fiber–matrix load transfer in HPC. Full article

Despite the growing use of tessellated and patterned façades in contemporary architecture, their thermal performance, particularly in cooling-dominated educational buildings, remains insufficiently quantified, with existing studies largely prioritizing daylighting or aesthetic outcomes over energy-driven thermal behavior. This study aims to systematically evaluate how different tessellated façade geometries and perforation ratios influence thermal performance and cooling demand in a Mediterranean climate, and to identify an optimal façade configuration that balances multiple thermal objectives. Three tessellation typologies—nature-inspired (Voronoi), Islamic geometric, and folded origami-based patterns—were parametrically generated and applied as external shading screens to an educational building. Annual thermal simulations were conducted using Climate Studio to assess four performance metrics: solar heat gain, energy use intensity, hours of overheating derived from operative temperature, and peak cooling demand. A post-simulation, data-driven, multi-objective, decision-support approach was applied using Compromise Programming to systematically evaluate and rank discrete façade alternatives based on multiple thermal performance criteria. Results indicate that all tessellated façades reduce solar heat gain and peak cooling demand relative to the unshaded baseline, with performance strongly dependent on both geometry and perforation ratio. Lower perforation ratios (20%) consistently outperform more open configurations, while Voronoi-based façades achieve the most balanced overall thermal performance across all evaluated criteria and emerging as the top-ranked solution. The study’s novelty lies in its comparative, cooling-focused evaluation of fundamentally different tessellation logics using transparent, decision-oriented optimization rather than subjective comfort indices or computationally intensive evolutionary algorithms. Beyond its specific findings, the research provides a transferable methodological framework for integrating geometry-informed façade design into early-stage decision-making, supporting climate-responsive and energy-efficient educational architecture in Mediterranean and similar climates. Full article

The urban heat island effect is strongly linked to the use of dense mineral pavements with high thermal inertia and lacking passive heat dissipation mechanisms. This article evaluates the potential of evaporatively cooled concrete pavers, based on capillary action and evaporation by incorporating recycled, bio-based, and lightweight materials to develop functional porosity. Ten paver formulations were developed using natural or recycled sand, hemp fibers and shives, and lightweight aggregates. Compressive strength, density, capillary absorption, and thermal behavior were characterized. Tests were conducted outdoors in full sunlight over 48 h in comparison with reference urban materials. The results show that capillary action alone is insufficient to induce effective cooling. The raw recycled sand formulation exhibits high capillary absorption but reaches maximum temperatures of 43–44 °C, which may be due to its low interconnected porosity that limits evaporation. Conversely, formulations incorporating bio-based materials or lightweight aggregates showed a more favorable balance between water availability, reduced density, and surface cooling performance. Hemp-based pavers reach maximum temperatures of 38–40 °C, while those incorporating expanded clay range between 37 and 39 °C, representing a reduction of 7 to 13 °C compared to bitumen and maintaining mechanical strengths suitable for pedestrian use. The results suggest that effective evaporative cooling is associated with sufficient capillary absorption, efficient water transfer toward the surface, and moderate density limiting heat storage. This study demonstrates that high capillary absorption alone does not ensure effective evaporative cooling. By systematically comparing recycled, bio-based and lightweight aggregates, the results reveal that evaporative cooling efficiency probably depends on the functional connectivity of the pore network and on a moderate material density limiting heat storage. Full article

Rapid urbanization and the decline of inner-city areas have led to a sharp increase in vacant houses in large cities. Cities are increasingly converting vacant land into green space to mitigate associated negative externalities. This study quantifies the urban heat island (UHI) mitigation effects of green infrastructure using meta-analysis and applies the derived relationships to predict both on-site and surrounding cooling effects for vacant land. First, we conducted a meta-analysis of published studies reporting the cooling effects of green infrastructure and derived regression equations relating green-space area to (i) cooling within the green space, (ii) cooling in the surrounding area, and (iii) the spatial extent of the cooling effect. Second, we applied these equations to two high-density areas in Sungui-dong, Nam-gu, Incheon, Republic of Korea. The results suggest that introducing a neighborhood park at Site A (7559.5 m²) would reduce air temperature by up to 2.751 °C within the park and by 1.507 °C up to 62 m beyond the park boundary. A pocket park at Site C (992.1 m²) would reduce air temperature by up to 2.269 °C within the park and by approximately 0.92 °C in the surrounding area. These findings provide quantitative evidence that green infrastructure can serve as an effective environmental intervention and support the adoption of climate-responsive urban regeneration policies. Full article

This paper presents a collaborative optimization design methodology aimed at improving heat dissipation efficiency through the modulation of microstructural variations. The approach addresses the thermal protection requirements of high-temperature components, such as ceramic matrix composite turbine blades, which are subjected to complex and elevated thermal loads. Through the integration of numerical simulation and experimental validation, a bidirectional mapping model linking carbon nanotube (CNT) content with the macroscopic anisotropic thermal conductivity of the material was developed. Furthermore, a thermal conduction analysis and optimization framework for Ceramic Matrix Composite (CMC) high-temperature components under non-uniform thermal loads was established. This study expands the adjustable range of the material’s thermal conductivity by allowing flexible modulation of carbon nanotube content. The results demonstrate that this methodology effectively enhances the heat dissipation capacity of CMC materials in extreme thermal environments: the maximum surface temperature of the optimized flat plate is reduced by 8.96%, the peak temperature gradient is lowered by 46.64%, and the maximum thermal stress is decreased by 38.17%. This research provides new insights into the comprehensive integration of thermal dissipation requirements for CMC hot components. Full article

Long-term time series forecasting (LTSF) is critical for modern power systems, energy management, and grid planning. Yet virtually all existing forecasting models employ stationary activation functions that apply identical nonlinear mappings regardless of temporal context—a fundamental mismatch with real-world load data, which exhibits strongly regime-dependent dynamics such as summer demand peaks, winter heating patterns, and overnight low-load periods. We address this gap by proposing TC-KAN (Time-Conditioned Kolmogorov–Arnold Network), the first forecasting architecture to augment KAN activation functions with position-aware coefficient parameterisation. The core innovation replaces the static polynomial coefficients in standard KAN activations with position-conditioned coefficients produced by a lightweight positional-embedding MLP, providing additional learnable capacity beyond standard KAN while adding negligible parameter overhead. TC-KAN further integrates a dual-pathway processing block—combining depthwise convolution for local temporal pattern extraction with the time-conditioned KAN layer for enhanced nonlinear transformation—within a channel-independent framework with Reversible Instance Normalisation. Experiments were conducted on four standard ETT benchmark datasets and the high-dimensional Weather dataset. TC-KAN achieves superior or competitive accuracy in most configurations while requiring merely 51K parameters—approximately 40% of DLinear and ∼100× fewer than iTransformer. On ETTh2, TC-KAN reduces the mean squared error by up to 61.4% over DLinear, and matches the current state-of-the-art iTransformer on ETTm2 at a fraction of the computational cost. This extreme parameter reduction circumvents the steep memory bottlenecks endemic to massive Transformer models, positioning TC-KAN as a highly practical architecture tailored precisely for resource-constrained edge deployments—such as on-device load forecasting inside smart grid sensors and industrial IoT controllers. Full article

Watermelon juice is a nutritious yet highly perishable beverage. Conventional thermal pasteurization ensures safety but degrades heat-sensitive nutrients, color, and flavor. Induced electric field (IEF) is an emerging technology that inactivates microorganisms while better preserving quality. However, its effects on the comprehensive quality retention of watermelon juice during storage remain underexplored. This study investigated the efficacy of IEF treatment on the microbial inactivation and quality preservation of watermelon juice during 25 days of storage at 4 °C. Freshly extracted watermelon juice was subjected to low-temperature IEF at 65 °C (IEF1) for 101 s and 60 °C (IEF2) for 88 s, with conventional pasteurization (65 °C, 30 min) as a control. The results showed that no colonies were detected in the IEF2 group throughout the 25-day storage period. Both IEF treatment and pasteurization effectively inhibited juice acidification. Soluble solids content and electrical conductivity remained stable under refrigeration, and the IEF group showed slower and more controllable acidity on day 25. Notably, the IEF1 group retained the highest lycopene content at the end of storage, while the IEF2 group maintained the highest total phenolic content (TPC). Furthermore, IEF treatment effectively mitigated color deterioration and preserved carbohydrate stability during refrigeration. Flavor analysis revealed that the taste profile of the IEF2 group at the initial storage stage closely resembled that of fresh watermelon juice. Over the 25-day period, the relative content of key volatile compounds characteristic of fresh watermelon decreased by only 3.64% in the IEF2 group. Full article

With global warming and accelerated urbanization, building air-conditioning (AC) releases more heat into the environment, exacerbating the urban heat island (UHI) effects and increasing building cooling energy consumption. Existing research has limited quantification of the impact of air-conditioning anthropogenic heat (ACAH) on the cooling energy consumption of different types. This study aims to explore the distribution characteristics of ACAH and its impact on residential building energy consumption. Firstly, typical residential buildings in the Pearl River Delta region were selected as a case study. Field experiments were conducted to measure temperature and humidity at 0.5 m, 1 m, 2 m, and 3 m from the outdoor unit, alongside ambient temperature and wind speed. Three grid densities were applied to verify the CFD model, with a prediction error of less than 0.3 °C at 0.5 m under a medium grid. The simulated temperature at 1 m from the outdoor unit under calm wind conditions was compared with field measurements to reveal the horizontal and vertical distribution characteristics of ACAH. Secondly, the effects of different building shapes, ambient temperatures, and wind speeds on the spatial distribution of ACAH were investigated. Finally, EnergyPlus (V23.1.0) was employed as the building energy simulation software, with its microclimate coupling interface implemented via Python scripts to quantify cooling energy consumption variations across different building floors under ACAH influence. Results indicated that ACAH exhibits significant horizontal non-uniformity, exerting the greatest impact within a 0.5 m radius (affected air temperature 4.3 °C higher than ambient). Vertically, localized heat accumulation occurs in the building’s central area, with air temperature 3.5 °C higher than at the bottom. Furthermore, compared to fixed meteorological conditions, the cooling energy consumption difference across floors considering ACAH reaches approximately 7.8%. This study provides accurate meteorological boundary conditions for building energy assessment and supports microclimate management in residential areas. Full article

This study investigates the effects of vehicle air-conditioning parameters on cabin thermal environment and occupant comfort. Computational fluid dynamics and discrete particle simulations involving different inlet-vent angles, inlet relative humidity (RH) levels, and occupant counts were conducted to analyze airflow, temperature, and RH. Thermal comfort was assessed using predicted mean vote (PMV), predicted percentage of dissatisfied (PPD), equivalent homogeneous temperature, and mean age of air (MAA). As a result, the uniform airflow at a 30° inlet angle provided the best global thermal comfort based on PMV (0.49) and PPD (10.02), whereas a 0° inlet angle improved local comfort around the chest area. Maintaining an inlet RH of 40–50% enhanced overall thermal comfort. Increasing the occupant counts raised the average cabin temperature to 301.76 K (Case 9), while also affecting local airflow patterns and MAA distributions; the addition of rear-seat occupants increased the local temperature around the driver’s left hand. These findings provide practical guidance for vehicle heating, ventilation, and air-conditioning system design, indicating that ventilation strategies should consider global comfort indices, localized airflow, thermal patterns, and particle removal performance. Overall, this parametric study highlights the association between vehicle cabin conditions and thermal comfort, providing baseline data for digital twin–based adaptive ventilation systems. Full article