Search Results (11,331)

To improve temperature uniformity and reduce thermal stress-induced cracking during laser directed energy deposition (laser DED) repair of TiAl blades, this study proposes a refined induction heating coil design based on coupled electromagnetic-thermal finite element simulation. A temperature-dependent model of the induction heating process for a cast 45XD TiAl blade was established and used to compare circular and elliptical coil cross-sectional shapes. The elliptical coil reduced the magnetic field concentration at the leading and trailing edges and decreased the maximum temperature difference across the blade cross-section to below 100 K, thereby improving transverse temperature uniformity. To further improve the temperature distribution along the blade length, a variable-pitch solenoid coil with sparse turns in the middle and dense turns near both ends was designed. This arrangement improved the balance between local heat generation and heat dissipation and reduced the temperature variation within the central 10 cm region of the blade to about 10 K. Experimental validation showed engineering-level agreement with the simulation results, and the blade body was stably maintained at 1020–1030 K, satisfying the preheating requirement for laser DED repair of TiAl blades within the tested design set. Full article

The construction industry is under increasing pressure to reduce its carbon footprint, driving the development of low-carbon construction technologies. Printable concrete has attracted increasing attention in the construction sector due to its advantages in automation and material efficiency, which are considered beneficial for sustainable and low-carbon construction practices. However, its structural performance under fire exposure remains insufficiently understood, particularly regarding the anisotropic mechanical response induced by layer-by-layer fabrication. This study experimentally investigates the mechanical behavior of printable concrete at ambient temperature and after exposure to elevated temperatures of 200 °C, 400 °C, and 600 °C. Manually printed specimens were prepared to replicate the layered characteristics of printable concrete, while cast concrete specimens served as a reference. Results show clear anisotropy in compressive strength among the X, Y, and Z loading directions, with the Z-direction exhibiting the highest strength due to improved interlayer integrity. Compared with cast concrete, printable concrete showed up to 37.77% lower compressive strength at ambient temperature. After thermal exposure, the compressive strength of printable concrete decreased by 16.68%, 34.40%, and 37.54% after exposure to 200 °C, 400 °C, and 600 °C, respectively, while the elastic modulus decreased by up to 78.18%. Mass loss and surface cracking intensified with increasing temperature, reflecting progressive dehydration and microstructural deterioration. These findings provide important insights into the fire performance and post-fire structural assessment of printable concrete. Full article

Aim: We aimed to provide a structured ex vivo protocol for cardiopulmonary micro-CT that combines gelatin–barium sulfate (gelatin–BaSO₄) contrast medium with agar embedding in neonatal canine cardiopulmonary specimens. Materials and Methods: Heart–lung specimens from 23 puppies that died shortly after birth were collected, stored at −20 °C, and then slowly thawed prior to imaging. Before perfusion, body mass and heart–lung complex mass were recorded. Body mass ranged from 140 to 951 g, and heart–lung complex mass ranged from 1.2 to 51.2 g. The cranial and caudal venae cavae, the brachiocephalic trunk, and the left subclavian artery were ligated. A catheter was introduced into the thoracic aorta. Contrast was prepared by dissolving porcine gelatin in hot water and mixing with a commercial BaSO₄ suspension. The mixture was maintained at a warm temperature to remain free-flowing and was delivered at low pressure until uniform opacification of the coronary and pulmonary arteries was observed. After in situ gelation, the organs were embedded in warm agar and sealed to limit motion and dehydration. Scans were performed on a benchtop system (120 kV, ~83 µA, ~1200 projections, ~2 s exposures; voxel ~40 µm). Reconstruction was performed in XMReconstructor, with post-processing in Falcon and RadiAnt. The reconstructed micro-CT datasets were reviewed anatomically by a medical cardiologist and a veterinary cardiologist, whereas vascular filling was evaluated semi-quantitatively by three observers with expertise in veterinary anatomy and cardiology. Results: In all specimens examined, the main coronary artery course was assessable. Conclusions: The gelatin–BaSO₄ contrast medium combined with agar immobilization provides a simple, lead-free, and affordable approach for structured cardiopulmonary micro-CT in very small post-mortem specimens. In the examined specimens, the workflow provided visually consistent low-pressure vascular opacification without gross evidence of vessel rupture or motion-related acquisition failure under the conditions of this study. Practical mitigations included temperature/viscosity control, avoidance of phosphate buffers, container sealing, and minimization of particle aggregation, bubbles, and dehydration. The protocol may complement conventional autopsy in very small post-mortem specimens in similar ex vivo research settings. Full article

This article examines how social science has recurrently positioned Islam as a problem-case for European narratives of modernity, simultaneously comparable as ‘a religion’ yet cast as the religion that ‘doesn’t fit’ secularisation, differentiation, and liberal public-reason expectations. Moving beyond the view that social science merely misdescribed Islam, this article argues that Islam has often been made to carry an explanatory burden internal to Europe’s self-narration, a limit-case through which stalled secularisation, anxious liberalism, and contested universals are rendered intelligible and governable. The article returns to canonical texts that helped establish such comparative imagination, including Hegel’s philosophy of history, Weber’s typologies of religious ‘bearers,’ and Gellner’s account of Islam as a comprehensive ‘blueprint’ of social order, to show how durable contrast effects were installed and later reactivated in contemporary debates on secularism, gender, security, and belonging. Drawing on Asad’s critique of the category ‘religion’, the article theorises ‘disruption’ as a recurring genre through which Islam is made exceptional, disruptive to secularisation theory, to accounts of modern differentiation, and to liberal self-understanding. It concludes by appealing to a reflexive sociology of religion that historicises its own categories, compares entanglements rather than civilisations, and treats Muslim intellectual traditions as theory-producing interlocutors rather than merely empirical ‘data’. Full article

In a steel continuous casting mold, argon bubbles injected through the submerged entry nozzle undergo transport, coalescence, and turbulent breakup, producing a polydisperse bubble swarm that affects flow stability and defect formation. In this study, an Euler–Lagrange model coupled with bubble collision coalescence and turbulence-induced breakup sub-models was established and validated using water model observations. Three daughter-bubble volume distribution models were compared in terms of bubble-cloud morphology, number-fraction distribution, and median-diameter evolution at different gas flow rates. For the median bubble diameter at different gas flow rates, the M-type model gives the lowest mean absolute error of 0.0349 mm. Large bubbles with diameters greater than 2.5 mm accounted for about 4% of the total number and were mainly concentrated near the SEN, whereas small bubbles with diameters of 1.0–1.5 mm accounted for about 60% and were dispersed throughout the upper recirculation region. Mechanism analysis further shows that bubble transport is drag-dominated in the high-velocity jet region, while buoyancy becomes more important in weaker flow regions; turbulent breakup is localized mainly in high-dissipation regions. Full article

The foundation of nuclear power plants is special as large-scale earth filling is often required. The properties of the backfill soil differ significantly from naturally deposited soils with regard to deformation and bearing capacity. For pile foundations, a thick backfill layer near the top may change the bearing mode around the pile. In this paper, six cast-in-place rock-socketed piles were tested, with three vertical loading tests and three horizontal loading tests. The lengths of four piles are 35–40 m, while the other two piles reach 55 m. The results show that shorter piles with more parts in the backfill layer can endure a hoop-tightening effect that caused by dilatancy at the upper part of the pile, resulting in very little frictional resistance being provided by the lower soil and smaller vertical displacement of the whole pile. The typical mechanism of transition from static to dynamic friction between soil and piles that leads to shaft resistance is more apparent for longer piles, but inhomogeneous soil like the backfill layer will make the transition complex. When subjected to lateral loading, piles with better integrity show more pronounced elastic features, smaller maximum horizontal displacement, and less residual horizontal displacement. The selection of the proportional coefficient for determining piles’ horizontal bearing capacity should correspond to the specific load and displacement in backfill soil. The results and in-depth analysis of the piles’ bearing capacity in backfill soil will provide intuitive experience for the analysis of pile foundations, thus offering references for the design and construction in similar engineering. Full article

Polymeric membranes are widely investigated for CO₂ separation; however, their performance is often limited by the permeability–selectivity trade-off. Incorporating metal–organic frameworks (MOFs) and designing composite membrane architectures are promising strategies to overcome these limitations. This study aims to evaluate the effect of incorporating MOF-74 (Cu and Ni variants) into a polydimethylsiloxane (PDMS) selective layer supported on a polysulfone (PSF) membrane for enhanced CO₂/N₂ separation performance. Dual-layer PDMS/PSF composite membranes were fabricated via phase inversion for the PSF support, followed by solution casting of the PDMS/MOF layer. The developed membrane architecture introduces a synergistic design that combines the mechanical robustness of PSF with the selective transport capability of PDMS and the strong CO₂ affinity of MOF-74, offering an effective strategy for improving gas separation efficiency. Gas permeation performance was assessed using single-gas CO₂ and N₂ measurements at feed pressures of 2–5 bar. The incorporation of MOF-74 improved CO₂ transport properties, with the 1 wt.% Cu-MOF-74 composite membrane achieving a CO₂ permeance of 912.5 GPU and a CO₂/N₂ ideal selectivity of 94.75. The dual-layer configuration significantly enhanced permeance compared with unsupported mixed-matrix membranes while maintaining selectivity. Additionally, the composite membranes exhibited improved mechanical strength due to the PSF support layer. The findings demonstrate that dual-layer PDMS/PSF composite membranes incorporating MOF-74 provide a promising proof-of-concept approach for improving CO₂ separation performance. Further studies involving mixed-gas testing and long-term stability are required to assess their practical applicability. Full article

To optimize the overall performance of as-cast 8021 aluminum alloy billets for power battery foil, this study explores how Ce addition (0–0.4 wt.%) regulates microstructure, mechanical properties, and corrosion resistance via second-phase reconstruction. Microstructure characterization, mechanical property testing and electrochemical corrosion tests were performed. The results show that Ce addition first refines, then stabilizes, and finally coarsens α-Al grains. The addition of 0.2 wt.% Ce promotes the formation of tentatively identified dispersed Al–Ce–Fe ternary phases, achieving the optimal combination of ductility (elongation: 42.7%) and strength (tensile strength: 95.0 MPa), as well as superior corrosion resistance (i_corr = 2.79 × 10⁻⁷ Acm⁻²). Excessive Ce led to possible precipitation of the Al₂Ce phase and grain coarsening, deteriorating alloy properties. In conclusion, 0.2 wt.% Ce is the optimal content to balance the microstructure, mechanical and corrosion properties of 8021 aluminum alloy, providing a theoretical basis for its compositional optimization of as-cast billet for battery foil applications. Full article

This article focuses on the research and development of innovative polymer-concrete composites for the manufacture of precision machine tool frames and critical mechanical engineering components. The relevance of this work stems from the need to replace traditional cast iron and cement concrete with materials with superior damping properties and thermal stability. The polymer matrix used in this study was ED-20 epoxy-diane resin, modified with (FAM) furan resin and cured with polyethylenepolyamine (PEPA), which together ensured minimal linear shrinkage (less than 0.5–1%) during polymerization. The focus was on the effect of multimodal filler distribution, including quartz sand, gabbro, and basalt, as well as reinforcing additives such as silicon carbide and fiberglass, on the final performance characteristics of the material. Experimental studies determined the key physical and mechanical parameters of the obtained samples. The results showed that the optimized composition (Smp_001) exhibited compressive strength up to 92.3 MPa, significantly exceeding that of standard high-strength concrete. It was established that the use of silicon carbide and glass fiber promotes the formation of a dense heterogeneous microstructure characterized by extremely low porosity (1.2–2.5%) and record-low water absorption (less than 0.05%). These characteristics guarantee high dimensional stability of the frames during prolonged contact with process fluids and cutting fluids. The scanning electron microscopy (SEM) and (EDS) energy dispersive X-ray spectroscopy methods confirmed the dense packing and high degree of interaction of the polymer matrix with the crystalline phases of the filler. This condition of the interfacial boundaries guarantees stable stress transfer throughout the entire volume of the material, which minimizes the risk of local damage during operation. The study confirmed that the developed material has vibration damping properties 6–10 times more effective than gray cast iron, a critical factor in improving machining accuracy on modern metal-cutting machines. The scientific novelty of the study lies in its substantiation of the synergistic effect of the combined use of basalt fillers and silicon carbide to achieve the precision properties of a structural material. Its practical significance is confirmed by the possibility of producing large-scale parts by casting without the need for complex finishing, opening up new prospects for modernizing the machine tool industry. Full article

The corrosion behavior of the EN AW-5083 alloy was investigated due to its widespread use in marine and transportation applications. The study examined the influence of microstructure development on corrosion behavior in both as-cast and homogenized conditions. Thermodynamic calculations, differential scanning calorimetry, and metallographic characterization were used to analyze solidification and microstructure development, while electrochemical testing was applied to evaluate corrosion resistance in a solution simulating severe outdoor exposure conditions, primarily marine, industrial, and transportation environments. The results show that the as-cast microstructure contains a heterogeneous distribution of anodic and cathodic intermetallic phases, which promotes localized corrosion. Homogenization at 520 °C led to the dissolution of the Al₈Mg₅ (β) phase, resulting in reduced sensitization effects and slightly improved corrosion resistance. However, high corrosion rates were observed in both metallurgical conditions, indicating limited resistance under the applied testing conditions. The study confirms that microstructural modification through homogenization influences corrosion mechanisms in EN AW-5083. Full article

In this study glycerol-plasticized sodium caseinate/polyvinyl alcohol NaC/PVA composite films were prepared by solution casting, and the effects of incorporating caffeic acid powder at different concentrations 0% 2.5% 5% and 15% w/w on structural mechanical barrier and postharvest performance were investigated. Caffeic acid (CA) (3,4-dihydroxycinnamic acid) is a naturally occurring phenolic compound commonly found in plant tissues and food sources such as apples, blueberries, and coffee. FTIR analysis revealed that shifts and broadening in OH bands indicated hydrogen bonding interactions between caffeic acid and the polymer matrix influencing structural organization. The pure NaC/PVA film exhibited high WVTR due to glycerol while maintaining low OTR. Adding 2.5% caffeic acid reduced WVTR but increased OTR through structural disruption. At 5% a continuous hydrogen-bonded network formed, restricting chain mobility and reducing free volume, thus lowering WVTR and OTR while preserving mechanical integrity. SEM micrographs revealed that high CA concentrations, particularly at 15%, led to aggregation-induced partial phase separation and consequent performance loss. Packaging treatments mainly affected physical and color attributes rather than primary metabolites. The NaC/PVA/5CA reduced weight loss and delayed sugar accumulation compared with NaC/PVA. Sugars peaked earlier in NaC/PVA but increased continuously in NaC/PVA/5CA, reaching maximum at the final storage stage. These findings indicate concentration-dependent mechanisms and highlight the potential of caffeic acid-based active packaging to regulate metabolism and extend postharvest quality. Overall results support its application in sustainable packaging systems for improved shelf life management. Full article

Aiming at the challenging issue of nonlinear coupling control between cooling intensity and solidification rate in the secondary cooling zone of round billet continuous casting, this study proposes an efficient 3D temperature field modeling method that integrates hybrid coordinate systems with equal-area meshing. The model is applicable to the temperature range of 800–1520 °C during the continuous casting process. With the modeling strategies of constructing an r-θ-z hybrid coordinate system and designing a dynamic equal-area meshing method, and combined with a topological structure optimization algorithm, the geometric adaptability and numerical stability of the model are significantly improved. Based on this, an explicit-semi-implicit dual-mode finite difference solution model is developed, where the explicit scheme meets real-time online calculation requirements, and the semi-implicit scheme combined with preconditioned Gauss–Seidel iteration enables high-precision offline simulation. Furthermore, a boundary condition model incorporating adaptive mold heat flux correction and multi-mechanism heat transfer in the secondary cooling zone is established. Based on Microsoft Visual Studio 2019 (Version 16.11) C++ development, SIMD vectorization and temperature gradient threshold optimization technologies are employed, resulting in a 35% improvement in computational efficiency. Industrial validation results show that, taking 42CrMo steel with a casting speed of 0.24 m/min and a cross-section of φ600 mm as an example, the deviation between the calculated surface temperature (887 °C) and the measured value (876 °C) of the round billet in the straightening zone is only 11 °C, and the calculation error of the cold billet diameter is only 0.325% (with a calculated value of 597.548 mm and a measured average value of 599.5 mm), both meeting the accuracy requirements for engineering applications. The model breaks through the limitations of traditional empirical formulas and provides theoretical support for digital control of continuous casting processes and quality optimization of high-alloy steels. Full article

Conventional CaO–SiO₂-based mold fluxes used in the continuous casting of rare-earth weathering steel are prone to severe slag–steel interfacial reactions, resulting in marked compositional changes and progressive property deterioration after rare-earth oxide pickup, which compromises lubrication stability and casting operability. In this study, a novel low-reactivity CaO–Al₂O₃-based mold flux was designed through phase-diagram-guided composition design, IMCT-based thermodynamic screening, and experimental investigation of melting, viscosity, and crystallization behavior. The originality of this work lies in establishing a design–validation framework for fluxes that remain stable after Ce₂O₃ absorption, rather than simply replacing the conventional CaO–SiO₂ system. Validation against literature SiO₂ activity data showed good trend consistency, supporting the use of the IMCT model as a semi-quantitative tool for composition screening. The results showed that CaO, Li₂O, and Ce₂O₃ exhibited relatively high activities, whereas B₂O₃ showed extremely low activity. When the Ce₂O₃ content exceeded 5 wt.%, the viscosity remained about 0.30 Pa·s, and when the w(CaO)/w(Al₂O₃) ratio was higher than 1.6, it stabilized at about 0.25 Pa·s. The minimum melting temperature, 1122.6 °C, was obtained at 5 wt.% Ce₂O₃. Compared with a conventional CaO–SiO₂-based flux, the developed flux showed similar initial processability but much better stability after absorbing 15 wt.% Ce₂O₃, with less severe deterioration in melting, viscosity, and crystallization behavior. These results provide scientific insight into mold-flux design under rare-earth oxide pickup conditions and practical guidance for improving the continuous casting of rare-earth weathering steels. Full article

Grain refinement is a crucial technological strategy for achieving microstructural homogenization and enhancing the mechanical performance of aluminum alloys. This study examines the synergistic effects of trace additions of NbB₂ and Ti on microstructural refinement and the enhancement of mechanical properties in high-pressure die-cast (HPDC) Al-Si series alloys. Through systematic investigations utilizing scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) analyses, the mechanisms by which trace additions of NbB₂ and Ti contribute to the synergistic refinement and strengthening of mechanical properties in HPDC Al-Si alloys are elucidated. The incorporation of NbB₂ effectively refines both the externally solidified crystals (ESCs) and secondary α-Al_II grains. The combined addition of NbB₂ and Ti further amplifies this effect, resulting in optimal refinement outcomes in the Al-Si series alloy, characterized by an ESC grain size of 19.1 μm and an area fraction of 27.5%, as well as an α-Al_II grain size of 6 μm. TEM observations reveal the formation of a Ti-rich transition layer between NbB₂ and Al with the synergistic addition of Ti and NbB₂, which fills interface nucleation vacancies and enhances refinement performance. Full article

Sulfur-containing medium-carbon microalloyed steel blooms are widely used for high-load automotive components, and reducing surface defects is important for improving product yield and lowering downstream processing costs. To address surface defects such as star cracks and microcracks in the continuous casting of these steel blooms, this study redesigned the mold flux on the basis of the steel’s solidification characteristics and crack susceptibility and carried out a twin-strand industrial comparative casting trial. Thermodynamic and thermophysical analyses indicated that the relatively high contents of S, Mn, and Ti/N in the steel promoted the precipitation of MnS and TiN–MnS complex inclusions along grain boundaries, severely weakening grain boundary cohesion. Meanwhile, the high specific heat capacity and low thermal conductivity further intensified thermal stress concentration in the solidifying shell, rendering the steel highly susceptible to cracking. Evaluation of the originally used mold flux (Flux A) revealed that its high melting temperature (1189 °C), long melting time (106 s), high break temperature (1170 °C), and poor crystallization behavior resulted in an excessively thin liquid slag layer (<5 mm) within the mold, making it difficult to provide adequate lubrication and stable heat transfer; these were key external factors inducing surface defects. Accordingly, the optimized mold flux (Flux B) was designed and prepared by increasing the basicity from 0.95 to 1.1, raising the Al₂O₃ content from 9.48% to 11.16%, increasing the F content from 4.93% to 5.58%, and reducing the carbon content from 13.85% to 6.97%. The rheological and crystallization properties of the flux were optimized in a coordinated manner, allowing uniform heat transfer through the crystalline slag layer while maintaining adequate lubrication. Industrial comparative trials demonstrated that Flux B stabilized the liquid slag layer at 8–10 mm, increased slag consumption to 0.56 kg/t, and significantly reduced surface defects such as star cracks and microcracks on blooms. The ultrasonic testing acceptance rate for rolled products increased to 98.6%, thereby meeting stringent quality requirements for the continuous casting of sulfur-containing, medium-carbon, microalloyed steel blooms. Full article