Search Results (936)

Optimizing the injection molding of short-fiber-reinforced thermoplastics (SFRTs) is a persistent challenge due to the complex interplay between processing parameters and final mechanical performance. To address this, we developed and validated a machine learning (ML) pipeline to maximize both the tensile strength and Charpy impact resistance in polyamide 6 with 30% glass fiber (PA6-GF30). Through a designed experimental campaign, we systematically varied four key process parameters—melt temperature (260–300 °C), injection pressure (600–1000 bar), packing pressure (400–800 bar), and cooling time (15–35 s). The resulting dataset was used to train and compare three different regression models: Random Forest (RF), Gradient Boosting (GB), and Support Vector Regression (SVR). Our findings indicate that the Gradient Boosting (GB) algorithm yielded the most reliable predictions, significantly outperforming the other evaluated models. Further analysis using SHAP (Shapley Additive exPlanations) identified packing pressure as the dominant factor influencing tensile strength (contributing approximately 40% to the prediction), while melt temperature emerged as the key driver for impact resistance (around 35% contribution). By integrating our best-performing GB model with a multi-objective genetic algorithm, we identified an optimal set of parameters that simultaneously enhances both mechanical properties. Among the evaluated models (Random Forest, Support Vector Regression, and Gradient Boosting), the Gradient Boosting algorithm achieved the highest predictive accuracy. Compared to the baseline condition (280 °C melt temperature, 800 bar injection pressure, 600 bar packing pressure, 25 s cooling time), experimental validation of these optimized settings demonstrated substantial improvement: tensile strength increased from 145 MPa to 171 MPa (an 18% enhancement), and impact resistance rose from 45 kJ/m² to 55 kJ/m² (a 22% gain). This work establishes that an integrated ML and optimization framework can serve as a transformative approach for high-precision manufacturing of advanced engineering polymers. The primary novelty of this work lies in the development of a fully integrated, bias-free methodological framework that explicitly couples physical interpretability with multi-objective optimization, bridging the critical gap between black-box predictions and actionable industrial insights. Full article

6082 aluminum alloy is widely applied in marine engineering, rail transportation and other industries owing to its excellent comprehensive performance. Welding heat source characteristics exert a decisive influence on the microstructure and mechanical properties of welded joints and become a major constraint for the application of medium-thick aluminum alloy welded structures. In this work, comparative tests of TIG and MIG welding were carried out on 16 mm thick 6082 aluminum alloy plates. Combining thermal simulation, metallographic observation and mechanical property tests, the temperature field distribution, microstructure, microhardness, tensile properties and bending properties of the two kinds of joints were systematically studied. The results show that TIG welding possesses high heat input, forming a broad temperature field with steep thermal gradients. Its weld microstructure is coarse and accompanied by severe coarsening of Mg₂Si precipitates, and the joint presents a highly fluctuating M-shaped microhardness distribution. The average tensile strength of TIG welded joints is 194 MPa, and all specimens fracture in the heat-affected zone. By contrast, MIG welding with low heat input produces a uniform temperature field, as well as a fine and homogeneous weld microstructure with dispersed precipitates. Its microhardness distribution is stable, and the average tensile strength reaches 256 MPa, 32% higher than that of TIG joints. Both welding methods deliver favorable bending performance. The difference in heat input and cooling behavior changes the grain evolution and precipitate characteristics and further dominates the final mechanical performance of joints. MIG welding is more suitable for multi-layer, multi-pass welding of 16 mm thick 6082 aluminum alloy. This work clarifies the correlation between heat input, microstructure and mechanical properties, and the optimized process can effectively improve the microstructural uniformity of the weld joint and enhance its mechanical properties. Full article

Heat-treatable aluminum alloys are widely used in aerospace and automotive industries for high-performance structural applications. However, their processing through conventional fusion-based additive manufacturing is limited by solidification-related defects, such as hot cracking, porosity, and elemental segregation. To overcome these limitations, friction-based additive manufacturing (FBAM) has emerged as a promising solid-state alternative. FBAM primarily includes friction stir additive manufacturing (FSAM), additive friction stir deposition (AFSD), friction screw extrusion additive manufacturing (FSEAM), and friction rolling additive manufacturing (FRAM), which differ in feedstock form and process configuration. In these processes, feed material is consolidated through frictional heat generated below the melting temperature, enabling the formation of refined equiaxed microstructures while minimizing solidification defects. Despite these advantages, significant challenges persist in processing heat-treatable aluminum alloys, particularly the 2xxx, 6xxx, and 7xxx series. These include non-uniform microstructure and mechanical properties along the build direction; precipitation instability; process-induced defects, such as tunnel formation; and mechanical properties that are often inferior to those of the corresponding base materials (BMs). Reported FBAM builds generally exhibit equiaxed ultrafine grains below 1 μm; however, the strength and microhardness of heat-treated alloy builds commonly remain around 70–75% of the corresponding BM. Following post-heat treatment, microhardness can be nearly fully recovered, whereas UTS typically reaches about 80–85% of BMs, often with an associated ductility reduction of nearly 50%. This review critically analyzes research reported over the past decade on FBAM processing of heat-treatable aluminum alloys, covering FSAM, AFSD, FSEAM, and FRAM. The key challenges related to microstructural evolution and mechanical performance are systematically discussed for each alloy series. Furthermore, mitigation strategies proposed in the literature, including process parameter optimization, in-process cooling, post-heat treatment, and nanoparticle reinforcement (e.g., SiC, TiC, Ni and ZrO₂), are evaluated. Finally, existing research gaps are identified, and future directions are proposed to support the development of robust, scalable, and high-performance FBAM processes for heat-treatable aluminum alloys. Full article

The automotive panoramic roof exhibits a large-size and thin-wall geometry, with a length-to-thickness ratio approaching the thousand level. This geometric feature makes its forming quality highly sensitive to forming conditions. During the glass molding process, variations in temperature evolution, loading, and cooling parameters may lead to residual stress accumulation and springback deformation, thereby affecting dimensional accuracy and final forming quality. In this study, a full-process finite element model was established and combined with an L16(4^5) orthogonal design to investigate the effects of five key process parameters—heating temperature, holding time, quenching air velocity, quenching air pressure, and quenching time—on the mean residual stress and mean springback displacement in the glass molding process (GMP). The results showed that, within the given parameter ranges, heating temperature, holding time, and quenching time had relatively pronounced effects on the mean residual stress; the mean residual stress was relatively low when the heating temperature was 680 °C, the holding time was 3 s, and the quenching time was 12 s. Heating temperature, quenching air velocity, and quenching time had relatively pronounced effects on the mean springback displacement; the mean springback displacement was relatively low when the heating temperature was 677.5 °C, the quenching air velocity was 13 m/s, and the quenching time was 10 s. Based on the orthogonal analysis, regression models for the mean residual stress and mean springback displacement were further developed, and parameter combinations were screened using the NSGA-III method. Experimental validation showed that the relative error of the mean residual stress was controlled within 15%, indicating that the established model could, to some extent, capture the relationship between process parameters and forming quality indicators, thereby providing guidance for precision forming and process optimization of large-scale thin-walled automotive panoramic roofs. Full article

This study added two types of resistant dextrin (RD), i.e., Bailong (BL) and Luo Gaite (LGT)) to a Japonica (cv. RXY) and an early indica (cv. IP44) rice during cooking and analysed the functional and structural properties of the cooked rice. Compared with no RD addition, 3–10% RD addition induced a declinein cooking time and an incrementin gruel solid loss. Further, 3–10% RD addition increased the hardness, chewiness, and springiness of cooked rice but decreased the cohesiveness. With increases in the added RD amount, the smell, structural appearance, palatability, taste, cool rice texture, and total score of the cooked rice all increased; the peak time and pasting temperature increased, but the peak, final, breakdown, and setback viscosities all significantly decreased. The enthalpy, conclusion temperature of gelatinisation, and gelatinisation peak width and height all decreased with increasing RD amount, but the peak temperature of gelatinisation increased. The addition of 3–7% RD did not change amylopectin ageing, but 10% RD significantly increased amylopectin ageing. RD addition reduced the protein weakness degree and starch breakdown torque of rice doughbut appeared to increase the amorphous and crystalline regions of cooked rice. The addition of 10% BL or LGT induced the formation of α-helix and random coil secondary protein structures in cooked rice, with optimal cooking properties and total sensory score. Microstructure analysis further showed that low-viscous RD induced the formation of new gel-like structures. In conclusion, 3–10% RD addition in cooking rice decreases amylose recrystallisation, weakens the protein structure, and induces new gel-like structures, enhancing the hardness, chewiness, adhesiveness, springiness, and sensory score of cooked rice. This study is useful for developing functionalcooked rice. Full article

This study proposes a multi-objective optimization strategy for the structural design of liquid-cooled channels in battery systems, aiming to identify liquid-cooled plate design schemes with better cooling performance and acceptable flow resistance. Optimal Latin hypercube sampling (OLHS) was combined with computational fluid dynamics (CFD) simulations to construct a CFD-generated dataset that includes the maximum temperature and system pressure drop. Then, modeFRONTIER was employed to integrate surrogate-model training, rapid prediction, and non-dominated sorting genetic algorithm II (NSGA-II) optimization, thereby obtaining the Pareto optimal set. The technique for order preference by similarity to ideal solution (TOPSIS) decision method was further introduced to determine the final optimal design. Results indicate that the optimized liquid-cooling system exhibits outstanding comprehensive performance in terms of balancing heat dissipation and flow resistance at a 5 C discharge rate. Remarkably, sensitivity analysis shows that inlet velocity is the dominant factor affecting the maximum battery temperature, with a correlation coefficient of −0.789. The maximum temperature of the battery module is effectively limited to 30.07 °C, while the flow pressure drop is only 799.58 Pa, achieving an excellent balance between heat dissipation efficiency and energy consumption. Full article

The ventilation system of a mine determines the comfort and safety of the underground working environment. Although many studies have been devoted to reducing the impact of underground heat damage, there are still few comprehensive studies or optimizations aimed at simultaneously considering heat damage prevention and control, exhaust of mechanical equipment, and methane leakage. To address this knowledge gap, a mine ventilation model was built and validated to analyze the impact of different numbers of top fans on the distribution characteristics of temperature and gas mass fraction. Subsequently, the impact of different blowing duct inlet temperatures and velocities on the capacity to cool and dilute hazardous gases was investigated. Finally, a comprehensive coefficient that removes the effect of dimension was proposed for evaluating the cooling and dilution performance of different top fan cases. The results show that a top fan is the most advantageous for cooling the mine, but has a poor ability to dilute hazardous gases. Three top fans have the best performance for diluting hazardous gases, which leads to some degree of heat diffusion, but obtains the maximum total comprehensive coefficient of 0.71246. Full article

Energy pile technology integrates geothermal energy exploitation with pile foundation bearing, yet accurately evaluating its thermo-mechanical performance remains theoretically challenging. To address the limitations of traditional load-transfer methods for accurately locating the neutral plane—which cause inconsistencies between computed pile-head axial forces and applied loads, and calculation discontinuities at the neutral plane—this study proposes an improved method using an iterative algorithm to eliminate unbalanced forces. Furthermore, based on a non-linear load-transfer function for pile-soil displacement compatibility, a model with well-defined parameters is established to capture the impact of long-term temperature cycles on the evolution of shaft resistance. A comprehensive calculation method for pile axial force and shaft resistance under cyclic temperature effects is thereby established. The analytical method is systematically validated against classical numerical methods and field test data from the London and Kunshan energy piles. Subsequent analysis reveals that heating–cooling cycles induce additional pile settlement. With increasing thermal cycles, the pile’s mechanical response evolves and ultimately stabilizes. Finally, increasing the applied mechanical load progressively attenuates the impact of cyclic temperature variations on the pile’s load-bearing performance. Full article

The Nam Xan gold deposit is located in the central Truong Son Fold Belt of Laos. It is a newly identified distal intrusion-related gold system (IRGS) in a continental arc setting. This study uses whole-rock geochemistry, Pb and S isotope systematics, and mineral-scale analyses to trace magmatic evolution and ore-forming processes. Whole-rock data indicate that the associated intrusive suite is a calc-alkaline volcanic-arc granite (VAG) series, derived from a subduction-modified mantle source with notable crustal contributions. Pb isotopes reveal mixing arrays rather than true isochrons. Monte Carlo modeling shows binary mantle–crust mixing for igneous rocks and ternary mixing with an additional radiogenic component in ore samples, indicating enhanced fluid–rock interaction during mineralization. Sulfur isotope data show a shift from magmatic sulfur (δ³⁴S ≈ −5‰) in early skarn-stage pyrite to heavier values (δ³⁴S ≈ +6‰) in gold-bearing stages, reflecting fluid evolution driven by cooling and redox changes. Mineral chemistry data demonstrate that gold is present both as invisible gold within arsenian pyrite and as free gold in late-stage fractures. Strong correlations between Au and As, along with elevated Co/Ni ratios and enrichments in Bi, W, and F, collectively support a magmatic-hydrothermal origin. These findings define a three-stage mineralization process: an initial phase involving high-temperature magmatic fluids, a main stage characterized by sulfidation and gold deposition, and a final stage marked by polymetallic overprinting. The Nam Xan deposit is therefore interpreted as the distal manifestation of a Permian arc-related magmatic system in which magmatic fluids migrated along structural conduits and precipitated gold through interaction with carbonate host rocks. The identification of these intrusions in the distal IRGS at Nam Xan informs regional exploration models in the Truong Son Fold Belt, demonstrating the potential of carbonate platforms near Permian intrusions for future mineral exploration. Full article

For continuous casting of strong reducing steels, the low-reactive aluminate-based mold flux consisting of CaO-SiO₂-Al₂O₃-CaF₂-Li₂O-B₂O₃-Na₂O with low SiO₂ content was designed. The correlation between the melt structure under high temperature and the crystallization phases during the cooling process and the change of viscosity was analyzed. The following conclusions were obtained. The polymerization degree of the mold flux consistently decreased as the w(CaO)/w(Al₂O₃) ratio increased from 0.93 to 1.65. Due to melt structure depolymerization, the viscosity at 1300 °C dropped from 0.132 Pa·s to 0.054 Pa·s. As the w(CaO)/w(Al₂O₃) ratio increases near the breaking temperature, the crystalline phases in the mold flux transition from LiAlO₂ to Ca₂Al₂SiO₇, and finally to a combination of Ca₁₂Al₁₄O₃₂F₂ and LiAlO₂. The rapid viscosity increase at the breaking temperature was primarily due to the precipitation of these phases. Furthermore, influenced by the changes in crystallization tendency and crystalline phase precipitation, the breaking temperature first decreased and then increased. Increasing the Li₂O mass fraction from 5% to 9% led to a decrease in the polymerization degree of the mold flux. Due to the depolymerizing impact of Li₂O on the slag network, the mold flux viscosity at 1300 °C decreased from 0.102 Pa·s to 0.047 Pa·s. The breaking temperature of the mold flux rose notably with a higher Li₂O mass fraction. At the breaking temperature, the crystalline phases in the mold flux transition from Ca₂Al₂SiO₇ to a combination of LiAlO₂ and Ca₁₂Al₁₄O₃₂F₂. The precipitation of these phases at the breaking temperature directly caused a rapid increase in viscosity. The results systematically reveal the coupling mechanism between melt structure, crystalline phase evolution, and viscosity variation of low-SiO₂ aluminate-based mold flux, which provides an important theoretical basis for composition design and performance regulation of mold fluxes for high-aluminum steel continuous casting. Full article

Parabolic solar dish–Stirling (PSDS) technologies are among the most efficient solar-to-electric conversion options, but their system-level modeling remains challenging because optical losses, receiver heat losses, package leakage, and Stirling engine non-idealities are strongly coupled under variable operating conditions. This study develops a modular, energy-consistent system-level framework that couples dish receiver optics and thermal behavior, hot-end package losses, and a non-ideal Stirling engine under variable charge (Qu-mode) control. The key novelty is a receiver engine heat-matching formulation in which receiver temperature, useful heat, working gas charge/mean pressure, and engine output emerge from a closed energy balance rather than from prescribed hot-side temperature, fixed heat input, or prescribed mean pressure. The framework was benchmarked in stages against the Mendoza receiver formulation, GPU-3/LeRC Stirling engine data, and EuroDish dispatch-level measurements. At the integrated EuroDish level, it reproduced heat input, cooler rejection, and net electrical output with mean absolute percentage errors of 2.90%, 4.07%, and 4.28%, respectively, while preserving explicit traceability of optical, receiver, package, engine, generator, and parasitic losses. A receiver formulation comparison showed that the final receiver treatment reduced the cooler rejection MAPE from 8.11% to 4.07% relative to the Mendoza-type receiver swap baseline. A limited-input transferability study for representative pressure-controlled dish–Stirling platforms retained peak power and efficiency within a ±10% envelope for the quantitatively assessed cases. Parametric studies further showed a broad engine speed optimum, a heat exchanger sizing trade-off governed by conductance and pumping/friction losses, stronger sensitivity to ambient temperature than wind over the tested EuroDish range, and cooling boundary effects that redirect fixed thermal input from electricity to rejected heat. The resulting framework provides a compact predictive basis for loss diagnosis, design studies, and control-oriented evaluation of PSDS units. Full article

In recent years, the use of warm-season species, which are species requiring less water, has been pursued in continental areas, but their dormancy and spring green-up need to be properly defined. In urban green areas, we find that small-scale microclimatic differences, while less intense than classical urban–rural gradients, still influence vegetation performance and spring green-up. This study examines the impact of microclimatic temperature variation on the spring green-up of different cool-season and warm-season turfgrasses in the continental climate of Madrid, Spain. The evaluation of colour change during the spring green-up process has been conducted using different vegetation indices, and mathematical models for correlating temperature with the indices’ values have been obtained. The results indicate that with average temperatures varying by about 1.3 °C and 0.9 °C in January and February, respectively, there have been marked differences in spring green-up, especially in cool-season turfgrasses, of almost one month. In contrast, differences in warm-season turfgrasses were reduced. Among the four vegetation indices, Canopeo has proved to be the best for detecting the early stages of spring green-up, with R² values ranging from 0.43 to 0.92. Meanwhile, the tailored greenness index for turfgrass was the most effective for determining the moment at which warm-season grasses achieve the colouration of cool-season grasses, with R² ranging from 0.79 to 0.85. Finally, the green leaf index was particularly valuable for identifying differences among species and sectors throughout the entire spring green-up process. Models based on this index achieve high R² values (0.57 to 0.94), but these models predict the moment at which warm-season grasses achieve cool-season grasses’ colouration later than it actually occurs. Understanding how turfgrasses respond to these localised microclimatic conditions is essential for selecting resilient species and improving maintenance strategies in parks, sports areas, and other components of urban green infrastructure. Full article

As the power density of office computing clusters rises to 200–250 W per chip, the substantial heat generated during operation not only impairs chip performance and shortens lifespan but also compels heating, ventilation, and air conditioning (HVAC) systems to operate at high loads. This increases energy consumption by 30–40% and causes indoor temperature fluctuations that reduce office workers’ comfort. Targeting centralized thermal management for such clusters, this study proposes a hybrid cooling strategy integrating outdoor natural cold air (as a continuous heat sink) with phase change materials (PCMs, for transient heat peak absorption). Six adjustable heating plates (power range: 50–250 W per unit, simulating 7 nm office chips) mimicked heat dissipation in a six-chip cluster. Latent heat storage (LHS) units served as passive cooling, with fan coils as auxiliary for natural/forced convection. By using PCMs (melting point: 48 °C) to absorb transient peaks and coils to utilize outdoor cold air, the system maintained circulating water at approximately 60 °C (steady-state equilibrium temperature under full-load conditions) and kept chip temperatures below 80 °C (industrial safety threshold). The hybrid system reduced combined pump and fan power to 125 W, achieving 75% energy savings compared to the HVAC system (500 W) and 40% savings compared to using only natural cold air (210 W pump and fan power). Positive pressure in the outdoor unit (increasing coil air velocity by 1.2 m/s relative to natural convection) further improved heat dissipation efficiency by 15%. Finally, this study quantifies the influence of PCM thermal conductivity and filling mass on the system’s temperature control performance through numerical simulations, providing direct evidence for parameter design of LHS units. Full article

There is a strong global increase in the installation of renewable energy power plants, due to increasing energy demand in the electricity generation sector and fast cost reduction. Recent studies indicate that the installation and operation of photovoltaic (PV) power plants have negligible microclimatic effects, although there are minor effects on night temperature in some cases, which, however, do not justify climate or environmental change. The development of solar energy and the installation and operation of PV power plants serve as a key solution for the energy transition to reduce carbon emissions and to address global warming. Despite the benefit of emission reduction, the deployment of solar energy through the installation of solar power plants causes land cover changes and may have minor effects on the surface energy balance by modifying roughness and albedo, biodiversity by disturbing habitats, and water resources by requiring water for cooling and cleaning. These changes may also lead to minor climatic, ecological, and social impacts. The objective of the paper consists of assessing the potential microclimatic effects of photovoltaic power plants based on satellite-based land surface temperature (LST) analyses. Specifically, the potential change in the land surface temperature, both under photovoltaic panels and on the panels, in relation to the temperature of the surrounding area is being examined in this study. The implementation is conducted in Mediterranean ecosystems, which are considered vulnerable agroecosystems due to increased climate variability. The final Landsat-based time series analysis further supports this synthesis, reporting that monthly LST differences between the PV Park and surrounding area are negligible and do not indicate a meaningful microclimate alteration attributable to PV operations. Accordingly, the evidence supports the core conclusion: utility-scale PV deployment does not constitute a driver of climate change, and the documented effects are best understood as localized surface–atmosphere energy-balance perturbations whose sign and magnitude depend on land cover, seasonality, and operation. Full article

Liquid-cooled battery thermal management systems are essential for maintaining thermal safety, temperature uniformity, and hydraulic efficiency in electric vehicle battery modules. However, improving heat dissipation often increases pressure drop and pumping demand, making the thermal–hydraulic trade-off a key challenge in cooling plate design. This study develops a CFD–GPR–NSGA-II-based multi-objective optimization framework for a mini-channel liquid cooling plate applied to a cylindrical 18650 lithium-ion battery module under a 4C discharge condition. The mini-channel thickness, wall thickness, and coolant inlet velocity are selected as design variables, while the maximum battery temperature, temperature difference, and pressure drop are used as objective functions. Sixty design samples are generated using Latin hypercube sampling and evaluated through CFD simulations. Gaussian process regression models are then constructed to approximate the nonlinear relationships between the design variables and the thermal–hydraulic responses, and the trained surrogate models are coupled with NSGA-II to identify Pareto-optimal solutions. The selected compromise design is finally verified using a full CFD simulation. Compared with the initial configuration, the CFD-verified optimized design reduces the maximum temperature, temperature difference, and pressure drop by 0.569 K, 0.557 K, and 338.612 Pa, respectively. Although the reduction in peak temperature is moderate, the optimized design improves temperature uniformity by 10.06% and reduces pressure drop by 43.25%, demonstrating a balanced improvement in thermal and hydraulic performance. A heat-load robustness check further confirms that the optimized design maintains a predictable thermal response under different heat generation levels. These results indicate that the proposed CFD–GPR–NSGA-II framework provides an effective and computationally efficient approach for designing mini-channel liquid cooling plates for electric vehicle battery thermal management. Full article