Search Results (1,091)

Microwave-assisted recovery provides a potential approach for restoring fracture damage in asphalt mixtures, but previous studies have mainly focused on heating and curing conditions, while the role of the pre-heating fracture state remains less understood. This study investigated microwave-assisted fracture energy recovery from a damage-state regulation perspective by comparing a control asphalt mixture (CAM) with a basalt fiber-reinforced asphalt mixture (BFAM). Semi-circular bending (SCB) tests were combined with an L9 orthogonal design to evaluate three pre-heating conditions, target surface temperatures of 45–85 °C, and curing times of 6–24 h. Rather than directly enhancing binder recovery, basalt fiber reinforcement increased the initial fracture resistance and altered the relative fracture condition reached under a given external load. The recovery index RI ranged from 20.7% to 55.9% for CAM and from 35.2% to 82.3% for BFAM. Main-effects ANOVA showed that the pre-heating damage condition had the largest main-effect contribution within the adopted L9 framework, reaching 82.3% for CAM and 95.2% for BFAM, substantially exceeding those of target surface temperature and curing time. Under a comparable external load of approximately 2.5 kN, CAM reached the 70% P_max condition, whereas BFAM remained at the 40% P_max condition, with corresponding mean RI values of 42.8% and 76.9%. These results support a proposed conceptual damage-state regulation framework within the investigated material and experimental conditions, in which basalt fiber reinforcement preserves a more favorable pre-heating state and thereby greater recovery potential. The findings highlight the importance of improving fracture resistance and applying microwave-assisted treatment before extensive fracture development occurs, while broader validation is required before generalizing the proposed framework to other materials or field conditions. Full article

To comply with stringent emission regulations, the deployment of hybridized powertrains is continuously expanding. However, architectures such as plug-in and parallel hybrids intrinsically reduce the overall runtime of the internal combustion engine (ICE). Because the battery state-of-charge (SOC) dictates intermittent engine activation, this operational strategy inevitably induces frequent cold-start events. This study investigates the thermal dynamics of commercial catalyst geometries (300–1200 cpsi, 2–8 mil) via 1D numerical simulations under real-world driving conditions. Without active heating, high-thermal-mass substrates unexpectedly outperform ultra-thin-wall variants by buffering against convective quenching during prolonged idling. However, integrating start–stop functionality halts cold exhaust flow, elevating mean temperatures and marginalizing geometric disparities. Evaluating electrically heated catalysts (EHCs) reveals that discrete preheating is highly inefficient due to rapid heat dissipation. Conversely, continuous closed-loop heating coupled with start–stop functionality sustains operational temperatures for over 90% of the cycle. Under continuous heating, substrate geometry ceases to dictate thermal performance; instead, it governs electrical efficiency. Low-thermal-mass monoliths minimize cumulative energy demand to 213 kJ (versus 277 kJ for high-mass variants), incurring a negligible CO₂ penalty. Consequently, future hybrid architectures must integrate lightweight EHCs to ensure sustainable emission control. Full article

The metastable β-phase Ti21S titanium alloy, characterised by its low Young’s modulus, oxidation resistance, creep strength, and high biocompatibility, has potential applications in aeronautical and biomedical fields. Despite these advantages, its adoption in additive manufacturing (AM) processes, particularly powder bed fusion with electron beam (PBF-EB), remains limited. A critical aspect of PBF-EB is the sintering phenomenon during preheating, which influences powder behaviour, thermal dissipation, and part quality. Insufficient sintering leads to poor energy dissipation and charge accumulation, while excessive sintering compromises powder reusability. This study investigates the sintering conditions required to optimise the PBF-EB preheating step for Ti21S. Thermogravimetric (TG) apparatus was employed as a controlled thermal treatment system to conduct a preliminary screening of the influence of temperature on powder sintering over a range of 400 °C to 700 °C. Parallel experiments were conducted using a PBF-EB machine to evaluate sintering behaviour. Scanning electron microscopy (SEM) was used to analyse the degree of sintering, while powder reusability was assessed by comparing the morphology and flowability of virgin and reused powders. The results show that conventional thermal treatment and PBF-EB preheating produce different sintering responses, likely because of the localised and rapid energy deposition associated with electron-beam heating. Nevertheless, controlled thermal treatment may provide a preliminary screening method for identifying temperature ranges for subsequent PBF-EB optimisation. Full article

Smelting with a high scrap ratio in converters holds significant importance for carbon reduction and emission reduction in the iron and steel industry. Under high scrap ratio conditions, the kinetic and thermodynamic conditions of the molten bath change significantly, leading to considerable differences in the elemental reactions and slag formation patterns during the smelting process. To investigate the reaction characteristics and dephosphorization behavior of the molten bath under different scrap ratios, this study conducted thermal simulation experiments of converter smelting with four scrap ratios (20%, 30%, 40%, and 50%) using a 500 kg induction furnace. Scrap preheating and supplemental heating agents were applied as needed. Slag petrographic analysis was carried out using SEM and EDS. The experimental results indicate that with scrap ratios of 20% and 30%, the carbon–oxygen reaction and slag formation efficiency are relatively high. The dephosphorization rate in the early stage of smelting can exceed 50%, and phosphorus is effectively enriched in the CaO–SiO₂ matrix phase, with the highest phosphorus distribution ratio observed at a 30% scrap ratio. In contrast, with scrap ratios of 40% and 50%, the carbon–oxygen reaction is slower, and the dephosphorization rate in the early smelting stage is less than 10%. In the 40% scrap ratio experiment, phosphorus began to accumulate significantly in the dicalcium silicate phase during the mid-smelting stage as the basicity increased. At a 50% scrap ratio, the silicate matrix remained the dominant phase throughout all smelting stages, and no distinct phosphorus-rich phase was formed. Full article

PV/T collectors and Air Source Heat Pump (ASHP) are widely studied for building heating, but solar intermittency and ASHP low-temperature frosting limit their large-scale deployment. A novel PV/T-ASHP coupled heating system is proposed to cut building carbon emissions and relieve ASHP performance degradation in cold zones. Circulating water cools PV/T panels to boost power generation, and the warmed water preheats ASHP evaporator inlet air to reduce frosting and defrosting frequency. With a Xi’an office building as the research object, validated TRNSYS 18.0 models are established for comparative analysis with conventional systems and cross-climate evaluation in Xi’an, Beijing, Shanghai and Chengdu. Results show the new system lifts PV/T combined efficiency by 17.56%, reduces energy consumption by 19.9%, and achieves an average COP of 3.2. Across climate zones, its COP rises 11.5–24.6% and 50-year carbon emissions fall 16.4–26.2%, supporting low-carbon heating promotion for office buildings. Full article

Color instability in anterior composite restorations remains a primary cause for clinical replacement. While pre-polymerization thermal modification is increasingly utilized in daily practice, its precise impact on phase-specific and long-term optical resistance against continuous thermal aging and aggressive dietary staining remains unclarified. This in vitro study evaluated the impact of pre-polymerization thermal modification (4 °C, 23 °C, and 55 °C) on the phase-specific and cumulative color stability (ΔE₀₀) of four anterior composite resins subjected to sequential thermal aging and prolonged coffee immersion. One hundred twenty specimens (n = 10) were prepared, and ΔE₀₀ was assessed using the CIEDE2000 formula at baseline (T0), post-thermal cycling (T1), and post-coffee immersion (T2). Mixed repeated-measures ANOVA revealed a significant three-way interaction (phase × material × temperature, p < 0.001), demonstrating that thermal conditioning effects vary by material formulation and aging dynamics. During thermal aging (ΔE₀₀ T0–T1), pre-polymerization cooling (4 °C) induced significantly higher discoloration in Estelite Sigma Quick compared to preheated conditions (p < 0.001). Following coffee immersion (ΔE₀₀ T1–T2), refrigeration at 4 °C significantly increased staining in Enamel Plus HRI (p = 0.026) and Estelite Sigma Quick (p = 0.007) compared to room temperature and preheated groups. For cumulative color change (ΔE₀₀ T0–T2), the material type was the primary determinant (p < 0.001), while the independent effect of temperature was not statistically significant (p = 0.395). In conclusion, preheating (55 °C) provides no significant cumulative advantage against staining, whereas refrigeration (4 °C) increases susceptibility to physical and chemical discoloration. The intrinsic chemical composition remains the critical factor driving long-term color stability. Full article

The aim of this work is to investigate the influence of different welding technologies on the mechanical properties and corrosion resistance of welded joints of SGH340D + ZMA steel with a Zn–Mg–Al (ZMA) protective coating. Two different welding technologies were used: the gas metal arc welding(GMAW) process at a welding speed of 0.8 m/min and laser welding at speeds of 2 and 4 m/min. Mechanical properties were determined using tensile testing and hardness testing. Corrosion resistance was estimated using a salt spray test. Residual stresses were determined experimentally using the drill hole method. The highest residual stresses were measured in GMAW-welded joints, while the lowest were measured in laser-welded joints at a speed of 4 m/min. The sample welded by laser at a speed of 4 m/min exhibited hardness values close to the upper acceptable limit, indicating that further increases in welding speed without preheating may lead to excessive hardness. All samples exhibited good corrosion resistance in a salt chamber. According to the results, increased welding speed reduced residual stresses but increased the risk of brittle fracture. Full article

Electron beam powder bed fusion (PBF-EB) of TiAl alloys exhibits different grain morphologies: equiaxed grains and columnar grains. However, the rule for controlling grain morphologies has not been found. In addition, the grain morphology is closely related to thermal gradient and growth velocity during PBF-EB. Here, thermal gradient and growth velocity are controlled by preheating temperature, beam current, and scanning speed. Based on the numerical simulation, the relationship between solidification parameters (thermal gradient and growth velocity) and process parameters (preheating temperature, beam current, and scanning speed) has been revealed. Meanwhile, the grain morphology of the topmost region of the PBF-EB-built Ti-48Al-2Cr-2Nb alloy can be controlled. In addition, the columnar-to-equiaxed transition is found in the PBF-EB-built Ti-48Al-2Cr-2Nb alloy. This is attributed to the PBF-EB technology belonging to the layer-by-layer stacking process, and the stacked layer reduces the thermal gradient and increases growth velocity in the remelting region. These findings will contribute to understanding the grain morphology evolution of TiAl alloys during PBF-EB, providing the principle for controlling the grain morphology of PBF-EB-built TiAl alloys. Full article

Background/Objectives: Injection moulding has become a predictable technique for transferring a diagnostic wax-up to direct composite restorations. However, conventional workflows that rely exclusively on injectable flowable composites may have limitations in material handling, mechanical performance, and the dimensional stability of the transparent silicone index. The purpose of this technical note was to describe a silicone-guided modification of the injection moulding workflow, referred to as the compression moulding technique, and to illustrate its clinical application in three representative cases. Methods: The proposed workflow combines a dual-layer silicone index consisting of a transparent polyvinyl siloxane material supported by a high-hardness bite-registration silicone with a preheated medium-viscosity resin composite. Following digital planning and diagnostic wax-up, the composite is positioned within the silicone index and adapted to the prepared tooth surfaces by controlled compression. Three clinical cases with different restorative indications were included to demonstrate the technique’s versatility. Results: In all three cases, the proposed workflow enabled accurate transfer of the diagnostic wax-up while providing improved stabilization of the transparent silicone index during composite placement. The combination of controlled compression, a rigid supporting silicone, and preheated paste composite facilitated material adaptation, minimized manual sculpting, and produced predictable esthetic outcomes in a minimally invasive chairside procedure. Conclusions: The compression moulding technique represents a practical modification of the conventional injection moulding workflow for direct composite restorations. The proposed protocol may improve index stability, material handling, and clinical versatility while maintaining the advantages of silicone-guided restorative procedures. Because the present article is intended to describe a technical workflow supported by representative clinical cases, further prospective clinical studies with long-term follow-up are required before conclusions regarding clinical superiority or long-term performance can be drawn. Full article

Magnesium (Mg) alloys are crucial for lightweight automotive design, underscoring the need for effective welding despite their poor weldability and susceptibility to defects such as cracks. The paper was prepared by reviewing available scientific databases of studies and patents using appropriate keywords. It reviews the properties, applications, and welding methods (fusion, friction, diffusion, explosive, and hybrid) of Mg alloys, assessing their advantages, disadvantages, and precautions. The importance of understanding the mechanical behavior and structural integrity of welded joints was highlighted. The impact of process variables on weld microstructure and properties, along with future research areas, is also addressed. AZ-series Mg alloys were found to be favored for weldability. For them, primary welding methods include GTAW, GMAW, LBW, and FSW. Trends emphasize solid-state techniques, advanced dissimilar metal joining, and AI optimization to enhance welding efficiency and quality. Welding of modern Mg-inclusive high-entropy alloys is under intensive development. Full article

To address the strength–ductility trade-off in titanium alloys, a comparative study was conducted on Ti-6Al-4V (TC4) alloys fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF). The L-PBF specimen primarily consisted of acicular α′ martensite with high residual stress. In contrast, the EB-PBF specimens, owing to a substrate preheating temperature of 740 °C and a reduced cooling rate (10³~10⁵ K/s), exhibited a stable and coarse α + β lamellar structure. Combined with the high oxygen content (0.24 wt.%) that provided solid-solution strengthening, this morphology enabled simultaneous attainment of a yield strength of 1120 ± 12 MPa and an elongation at fracture of 11.1 ± 1.3%. Notably, deformation-induced HCP→FCC phase transformation occurred in EB-PBF alloys, generating a dual-phase HCP/FCC structure that effectively accommodated plastic strain. These results highlight the superior potential of EB-PBF over L-PBF for fabricating titanium alloys with an exceptional strength–ductility synergy. Full article

This study investigates the integration of CO₂/H₂S separation and internal power generation in power- and biomass-to-liquid (PBtL) and fuel-assisted PBtL (FAPBtL) processes to enhance carbon efficiency and reduce external electricity demand. Four configurations (PBtL, FAPBtL-recycle, FAPBtL-purge, and Purge-to-Fuel (Purge-tF)) are evaluated through detailed mass and energy balances, thermal integration analysis, and techno-economic assessment. Reintegration of separated CO₂ eliminates carbon losses in the acid gas removal unit, increasing carbon efficiencies to approximately 98% for PBtL and Purge-tF, 97% for FAPBtL-recycle, and 79% for FAPBtL-purge. Increasing the carbon efficiency from 91% to 98%, for PBTL, comes from capturing 85% of the CO₂ downstream of the acid gas removal unit. In parallel, integration of a supercritical two-step reheat Rankine cycle with preheating enables the recovery of high-temperature process heat, increasing cycle efficiency from 42% to 55% and generating up to 61 MW of internal power. Although CO₂/H₂S separation introduces additional capital and energy requirements, the combined integration of carbon recycling and heat-to-power recovery improves overall system performance. The Purge-tF configuration achieves the lowest net production cost of 2.60 €/kg_fuel (2.11 €/L_fuel). Sensitivity analysis confirms electricity price as the dominant economic driver. The results demonstrate that strategic integration of carbon recycling and advanced heat recovery can substantially improve both the carbon utilization and economic viability of biomass-based synthetic fuel production. Full article

Laminar counterflow multi-branch flames provide a canonical configuration for investigating interactions between oxidizer-rich and fuel-rich streams in liquid-oxygen/methane combustion systems. This study numerically investigates their flame structure and stability under transcritical conditions, with stability characterized by the extinction strain rate. Ideal-fluid (IF), partial real-fluid (PRF), and real-fluid (RF) models are compared to distinguish the effects of real-fluid thermodynamics and high-pressure transport corrections. The multi-branch flame comprises two premixed branches coupled with a central diffusion branch. Heat release from the premixed branches creates high-temperature plateaus that preheat the stagnation-region mixture and sustain the diffusion branch. Although the three models predict similar flame topologies, the IF model gives an extinction strain rate of $3.306\times {10}^6{\mathrm{s}}^{-1}$, whereas both PRF and RF predict $3.256\times {10}^6{\mathrm{s}}^{-1}$. Thus, the ideal-fluid treatment slightly overpredicts the extinction limit under the present reference condition, while high-pressure transport corrections influence the ignition location, peak temperature, and thermal diffusivity. Increasing pressure from 10 MPa to 40 MPa raises the extinction strain rate from $9.336\times {10}^5{\mathrm{s}}^{-1}$ to $4.867\times {10}^6{\mathrm{s}}^{-1}$ by strengthening heat release and reducing thermal diffusion from the high-temperature region. Oxidizer preheating markedly enhances flame stability, whereas fuel preheating has a weak effect. These findings establish the connection between real-fluid thermodynamics, branch interaction, and extinction stability, providing a physical basis for model selection, operating-condition optimization, and stability-margin assessment in transcritical liquid-oxygen/methane combustion systems. Full article

A plethora of studies have demonstrated the bioactive properties of collagen peptides, including the promotion of wound healing and bone health. Research has demonstrated that these effects are attributable to their elevated biocompatibility and signaling capabilities. The present study investigated the effects of collagen peptides produced by enzymatic hydrolysis of perch scales on the induction of extracellular matrix formation and osteogenesis. The findings demonstrated that a combination of pre-heating and enzymatic hydrolysis resulted in the optimal peptide yield, with 94.9% of the peptides exhibiting a molecular weight below 1200 Daltons and containing elevated levels of hydroxyproline. The addition of perch scale collagen peptides to fibroblasts 890510-01F ATIT has been demonstrated to effectively induce the production of type I procollagen and fibronectin, a protein associated with the osteoblast phenotype and osteoblast differentiation. It is also worthy of note that experiments conducted using MC3T3-E1 osteoblasts indicate that collagen peptides significantly increased alkaline phosphatase activity by a factor of 1.46. This study demonstrates that collagen peptides derived from perch scales are enriched in bioactive peptides containing C-terminal tyrosine residues, including DYPRNHY and DPYNRHY. These findings provide a scientific basis for the future development of perch scale-derived collagen peptides as dietary supplements or functional food ingredients for promoting bone health. Full article

In this study a transient finite element model was developed to examine the temperature evolution of continuous casting blooms during reheating prior to rail rolling. The simulation was carried out using COMSOL Multiphysics 5.6, incorporating convective and radiative heat transfer mechanisms under a three-zone furnace (preheating, heating and soaking) temperature schedule. The temperature distribution and soaking uniformity were evaluated over a 7200 s heating cycle. The results indicate that proper adjustment of furnace setpoints enables the bloom center to reach approximately 1220 °C while maintaining acceptable temperature uniformity $∆T\le 50 ℃$. This study shows how numerical modeling can be used to improve thermal homogeneity prior to hot rolling and optimize reheating furnace performance. Full article