Search Results (5,988)

The growing demand for large, lightweight, heat-resistant, and multifunctional aerospace structures has raised the requirements for metal matrix composites in terms of defect minimization, performance enhancement, and near-net-shape manufacturing. Additive friction stir deposition of composites enables feedstock delivery, reinforcement mixing, and layer-by-layer consolidation in a thermoplastic state below the melting point of the matrix, thereby mitigating porosity, hot cracking, elemental segregation, reinforcement degradation, and excessive interfacial reactions commonly encountered in fusion-based additive manufacturing. This review summarizes recent advances in the application of this technology to the fabrication of metal matrix composites, elucidates the mechanisms of material flow, interlayer bonding, microstructural evolution, and defect formation during deposition, and discusses the effects of tool design, process parameters, and reinforcement characteristics on interfacial bonding, microstructure control, and mechanical properties. Remaining challenges include the uniform delivery and quantitative control of reinforcements, characterization of interfacial bonding and load transfer, forming stability of complex components, and evaluation of in-service performance; accordingly, thermo-mechanical-flow multiphysics models, multisensor closed-loop control systems, and unified quality-assessment methods should be developed to promote the engineering application of large-scale, multimaterial graded aerospace components. Full article

Building thermal performance has become a major concern as global warming intensifies and building energy demand is expected to rise by 30% by 2030. Bio-based construction materials offer a promising solution by improving thermal comfort and reducing operational energy use. This study presents a computational framework for optimising bio-based masonry block design through the integration of numerical simulation and data-driven modelling. A parametric thermal model was developed in COMSOL Multiphysics to simulate steady-state heat transfer through hollow masonry blocks with varying cavity geometries and material properties. A surrogate model-based approach was then used to generate a dataset of simulated block configurations, from which key thermal performance indicators, particularly heat flux, were extracted. These outputs were used to train a machine learning surrogate model capable of accurately predicting thermal performance across a wide design space without repeated finite-element simulations. The proposed workflow achieved an average heat-flux mismatch of 0.23%, reduced computational cost, and improved prediction accuracy by approximately 7%. In addition, the surrogate-assisted optimisation identified block geometries with substantially improved thermal performance compared with conventional reference configurations. The proposed methodology provides a scalable digital design framework for the development and evaluation of bio-based masonry materials. Future work will incorporate real-time sensor networks and Internet of Things (IoT) systems for the continuous monitoring and validation of masonry wall thermal performance. Full article

Geothermal energy piles (GEPs) synergistically integrate structural load-bearing with subsurface heat exchange, yet their deployment in marine soft clay prevalent along China’s eastern coast introduces complex thermo-hydro-mechanical (THM) challenges. Although the Modified Cam-Clay (MCC) model is extensively employed for such soils, regional parameter variability and quantitative sensitivity to energy pile performance remain insufficiently resolved. This study establishes a three-dimensional finite element model using COMSOL Multiphysics and conducts systematic sensitivity analysis by perturbing key MCC parameters (M, λ, and κ) within ±20% and ±40% around benchmark values for Shanghai marine soft clay. Results demonstrate that the compression index λ dominates pile head settlement control, with a ±40% perturbation inducing variations up to 0.7 mm—over five times more sensitive than M or κ—whereas all parameters exhibit negligible influence (<0.5%) on thermal exchange performance. Comparative analysis further reveals significant regional disparities, with Shanghai soft clay showing notably higher λ (0.29) and lower M (0.721) than Fuzhou, Shenzhen, and other coastal regions. Accordingly, for settlement-critical designs, λ should preferentially be determined from high-quality undisturbed sampling. Conservative λ values are to be used where uncertainties remain, laying a rigorous foundation for parameter-testing procedures and safety-factor calibration within GEP design. Full article

Selective laser melting (SLM) produces elemental segregation and nonequilibrium secondary phases in GH4169 superalloys, but the effects of P and C variations on grain-boundary phase evolution and high-temperature tensile behavior remain unclear. Alloys with primarily varied P (0.034–0.058 wt.%) and C (0.009–0.066 wt.%) contents were fabricated and heat treated identically. Microstructures were characterized by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM), and tensile properties were evaluated at 650 °C. The as-built alloys exhibited columnar grains, cellular substructures, cell-wall segregation, and Nb-rich Laves-phase particles. After heat treatment, cellular substructures largely disappeared, γ″ precipitates formed in the γ matrix, and fine Ti/Al-rich particles were tentatively attributed to γ′; δ phase, residual Laves phase, and MC-type carbides were present at grain boundaries. Increasing P reduced the δ-phase area fraction from 2.20% to 1.38% and changed its distribution from continuous chains to semi-continuous and discrete arrangements. Increasing C raised the MC-type carbide area fraction from 0.34% to 1.48% while decreasing the δ-phase area fraction from 1.68% to 0.98%, accompanied by carbide coarsening. The 0.050P alloy exhibited the highest yield and ultimate tensile strengths, whereas the 0.009C alloy showed the best strength–ductility balance. These results reveal distinct P- and C-related changes in grain-boundary phase evolution and tensile behavior at 650 °C. Full article

This paper presents a real-time browser-based platform for thermohydraulic characterization of a compact laboratory heating system, developed using the PolyVR research-grade virtual reality engine. Experimental measurements are retrieved at 1 Hz from a cloud-based database and processed via browser-native computational framework that continuously performs thermophysical modeling, hydraulic analysis and energy balance evaluation. The system calculates the rate of heat transfer (h), overall heat transfer coefficient (U), dimensionless numbers (Re, Pr, Gr, Nu), pump performance, heater efficiency and cumulative thermal energy. PolyVR provides the immersive environment in which the partial digital twin functionality is integrated alongside the browser-based thermohydraulic calculations. The whole system includes support for animations regarding flow diagrams, valve state indicators, thermal field visualization and manipulation of system elements. The system architecture is designed to work on desktops, head-mounted devices, as well as in CAVE (cave automatic virtual environment) systems with remote connection made possible via using ngrok tunnels. The experiments were separated into three categories (steady-state, dynamic and validation). Steady-state and dynamic datasets show that the browser computation with PolyVR achieves high-fidelity thermohydraulic analysis similar to that done in laboratory settings. The steady-state and transient datasets illustrate that browser-based computation provides highly accurate thermohydraulic simulation close to that of the laboratory reference computations. For all experiments performed on the platform, the deviation of measurements does not exceed ±0.5 K in temperature, ±5% in flow rate and ±1% in pressure. The energy balance is closed with a deviation of ±2–3%. Full article

Green chemistry aims to develop more sustainable and environmentally friendly chemical processes by reducing waste, minimising the use of hazardous substances, and identifying alternative catalysts and solvents. Traditional organic synthesis often relies on catalysts that are toxic, flammable, or corrosive, such as phosphoric acid, creating a need for greener alternatives. This study investigated the potential of ash derived from food industry waste as a green catalyst. Various waste materials were utilised, including onion and garlic husks, peanut skins and shells, hop and barley residues after beer production, and cocoa shells and beans. ICP-MS analysis was used to determine the content of 25 elements (Na, Mg, P, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb, B, Al, S, Ga, Rb, Sr, Ba, La) in the food industry waste ash. The catalytic activity of the ash was evaluated in the synthesis of acetylsalicylic acid from salicylic acid and acetic anhydride. Reactions were carried out in the presence of 20 mg of ash by heating the reaction mixture in a water bath at 80–100 °C. Reaction yields ranged from 11% (peanut shell ash) to 78% (barley ash). In addition to barley ash, good reaction yields were also obtained with hop ash, cocoa shell ash, and cocoa bean ash. The results demonstrated that ash-derived materials successfully catalysed the reaction, suggesting that metals present in the ash may play a role in catalysis. These findings indicate that food industry waste may represent a promising and sustainable source of catalysts for organic synthesis. Full article

The use of 3D-printed concrete (3DPC) for home building has been of interest to several newly formed 3D printing companies over the past few years. This interest is largely due to its time and material efficiency, as well as its flexibility in architectural design. Although the structural capabilities of 3DPC are still being researched, the enclosure aspects of printed buildings are not equally studied. Current applications of 3DPC for home building are more suitable for mild climates where there is limited risk from harsh weather and drastic temperature differences throughout the seasons. There is a void in understanding how 3DPC walls in cold climates will perform with respect to heat transfer through the wall, which can affect the energy consumption of the building. Therefore, this literature review will explore select numerical and experimental research studies that have been completed on the building science aspects of 3DPC walls and identify gaps for future research. While the main aspect of interest in building science for this study is related to the thermal conductivity property of 3DPC, other aspects are also addressed to a lesser degree. The review then focuses on the thermal performance of the printed concrete, the print configuration and the cavity infill, various waterproofing methods, and hygrothermal properties relating to humidity levels, freeze–thaw cycles, corrosion and mold risk. The research methodology for this review consisted of using keywords to search for relevant 3DPC documents with some reference to building science aspects, categorizing the literature contents based on relevance, recency and quantifiable data, providing a summary of the studies performed and their conclusions, and suggesting any remaining knowledge gaps that merit future studies. Based on the literature review, it is very unlikely that only adjusting the concrete mixture, changing the print configuration or infilling the cavities of 3DPC walls with insulation will satisfy thermal performance requirements across climate zones. The literature review identifies a few future research and study directions. To meet energy standards such as the International Energy Conservation Code (IECC) and avoid thermal bridging, studies need to explore how a continuous layer of insulation can be incorporated into the wall assembly, whether it is interior or exterior, and how it would affect energy consumption. The humidity distribution and risk of condensation across assemblies should also be further researched to determine if they impact the placement of continuous insulation, as well as the risk of corrosion for any structural metal elements in the assembly. Regarding ongoing 3DPC construction, this study shows that while there exists a good understanding of the material and print characteristics, there is a need to use sensors and monitoring systems within current 3DPC builds to gather data on the enclosure performance through different seasons for future improvement. Full article

Ti65 is a promising structural material for lightweight high-temperature aerospace components, yet the heat-treatment response of Ti65 fabricated by electron beam powder bed fusion (EB-PBF) remains insufficiently understood. In this study, EB-PBF Ti65 specimens were subjected to solution treatments at 800–1000 °C for different holding times followed by aging at 650 °C for 2–8 h. Microstructural evolution was characterized and tensile properties were evaluated at room temperature and 650 °C along the XY and Z directions. The as-built alloy exhibited a fine basketweave α + β lamellar microstructure with evident anisotropy. Increasing the solution temperature promoted α-lamella dissolution, elemental homogenization, discontinuity of grain-boundary α, and microstructural reconstruction. The 1000 °C/2 h + 650 °C/2 h treatment significantly improved room-temperature strength and transverse ductility, giving ultimate tensile strengths of approximately 1050 MPa and reducing anisotropy. At 650 °C, all specimens showed reduced strength but increased ductility; low-temperature solution treatment favored ductility, whereas 1000 °C-based treatments combined with appropriate aging improved elevated-temperature strength. Aging for 4 h provided a balanced strength–ductility combination, while longer aging enhanced yield strength but reduced ductility. These results demonstrate that tailoring solution and aging parameters is essential for optimizing the microstructure and mechanical performance of EB-PBF Ti65 alloy. Specifically, the 1000 °C/2 h + 650 °C/2–4 h regime achieved UTS of ~1050 MPa at room temperature and ~608 MPa at 650 °C, with XY-direction elongation increasing from 5.4% to 11.5%, representing a quantitative anisotropy reduction of approximately 53%. Full article

This manuscript presents the theory and experimental validation of low- and medium-temperature deicing technology that advances the recently developed Ice Cavitation Deicing (ICD) method. Conventional high-temperature ICD (HTICD) efficiently removes ice by explosively vaporizing a thin interfacial melted layer but operates at heating rates above 10⁶ K/s, high voltage, and maximum temperatures exceeding 400 °C. This study develops Low-Temperature and Medium-Temperature Ice Cavitation Deicing (LTICD and MTICD), extending ICD into the previously unexplored intermediate heating-rate regime. Analytical modeling based on energy conservation, transient heat diffusion, water thermodynamics, and thermal-stress analysis was combined with finite-element simulations and experimental testing. Several foil materials were evaluated over heating rates of approximately 10⁴–10⁷ K/s using capacitor banks of 0.1–35 mF. Experiments demonstrated effective removal of thick and thin ice at cavitation temperatures of approximately 120–200 °C, substantially below those of HTICD. The lower operating temperatures and heating rates reduce thermal stress, voltage, and current, enable practical low-voltage electrolytic capacitors, and expand the range of suitable materials. Thus, LTICD and MTICD provide a lower-temperature, more practical electrical architecture for future aircraft ice-protection systems. Full article

Computer models and protocols commonly used for superficial thermotherapy assume anatomically symmetric tissue geometries. However, anatomical variability, particularly the variability of the adipose tissue thickness, may have a significant impact on heat transfer and cause non-uniform thermal doses in the patient population. This paper studies the influence of anatomical asymmetry due to adipose tissue thickness on heat propagation during superficial thermotherapy based on combined computational and experimental analyses. A Finite Element Model of the lower limb was designed with anatomically representative layers and tissue thermal properties. Parametric simulations were conducted for medium (M) and extra-large (XL) models at hot-pack temperatures (38–44 °C) for 15 min. The simulation results were compared with experimental measurements on ex vivo porcine tissue. The results showed that the thickness of adipose tissue significantly affected deep-tissue heating. When the same heating condition was applied, the boundary temperature of the muscle was increased by ~1.38 °C for the 44 °C hot-pack in the M-size model and was restricted to 0.21 °C for the XL-size model. The experimental muscle temperature increased from 22.26 °C to approximately 23.3 °C after 15 min. Under the same initial temperature and nominal 38 °C heating condition, the perfused and zero-perfusion M-size simulations reached approximately 26.8 °C and 30.5 °C, respectively; these endpoint differences support a qualitative comparison rather than quantitative validation. These results show that anatomical asymmetry has a strong effect on heat transfer during superficial thermotherapy and challenge the precept that standard heating protocols provide similar thermal doses in different body morphologies. Full article

To address critical energy access challenges, overcome the limitations of conventional baking systems, and bridge the research gap in solar-assisted injera baking, this paper presents an experimental investigation of a photovoltaic (PV)-powered injera baking system integrated with a solar salt mixture for thermal storage. In addition to introducing the PV system to the injera baking application, this study incorporates self-regulating positive temperature coefficient (PTC) heating elements and a storage design that has not been previously investigated for injera baking—an integrated unit that combines the base plate and thermal storage to facilitate heat transfer during charging and discharging. The system’s performance was assessed by conducting experiments based on energy consumption during charging and the utilized energy during the cyclic baking process. Conducted in May, the test demonstrated that the charging process achieved a complete melting of the PCM within 6.26 h. Under a cycle of 5 min of average baking time followed by 9 min of plate reheating, the system produces 6 injeras from the stored heat with a significant amount still in the storage. The storage system exhibited an efficiency of 74.6% during charging and 65% during discharging. The findings from this research have the potential to address energy challenges in off grid communities, as well as within institutions that still rely on biomass for injera baking by managing solar energy intermittency and providing stable thermal output. For future work, we recommend incorporating customized plate type self-regulating heating elements with higher temperature ratings and non-stick baking plates to enhance performance. Full article

Fused silica–aluminum alloy dissimilar connections are in urgent demand in fields such as aerospace optoelectronic packaging, vacuum optical windows, and micro-electro-mechanical systems, yet the dramatic mismatch in thermal-expansion coefficient and thermophysical properties between the two materials has long been a bottleneck for reliable joining. Current ultrafast laser welding of such heterogeneous systems still suffers from prominent problems, including stringent optical contact requirements, high crack sensitivity on the fused silica side, and unclear coupling mechanism between clamping conditions and joint defects. This work systematically studies the joining process of femtosecond laser welding of fused silica and 6061 aluminum alloy dissimilar materials, focusing on the effects of scanning speed, pulse energy, scanning spacing, and fixture preload on the shear strength, microstructure, and elemental diffusion behavior of the joints. The results confirm that scanning speed and scanning spacing have a synergistic effect on heat input density; the magnitude of the fixture preload is a key factor determining the interfacial residual stress and crack sensitivity. By optimizing the scanning speed (6 mm/s) and combining it with a low preload and 140 μm scanning spacing, a high-strength heterogeneous joint with uniform elemental transition and no macroscopic cracks can be obtained. This study provides a detailed process-optimization approach for high-quality laser welding of dissimilar brittle/ductile materials. Full article

Heritage buildings sit outside most national energy codes, yet Palestine alone hosts over 3000 historic structures whose 80–120 cm two-leaf stone construction is absent from any published, measurement-grounded retrofit dataset. A 19th-century three-storey heritage building (Qaser Morcos, Bethlehem; net floor area 406 m², volume 2100 m³) was investigated through (i) in situ measurements (heat-flux meter to ISO 9869-1; infrared thermography; illuminance survey); (ii) a Heritage Building Information Model (H-BIM) built in DesignBuilder v7 with EnergyPlus 25.1 and the Jerusalem-centre typical meteorological year weather file, with end-uses other than heating, ventilation and air conditioning (HVAC) calibrated to three years of measured electricity records and the HVAC baseline comfort-normalised; (iii) a Heritage Impact Assessment per EN 16883:2017; and (iv) a 5000-run Monte Carlo uncertainty analysis on five envelope and system inputs. Two retrofit stages were evaluated: Stage 1 (passive and renewable measures—roof insulation, shading elements, LED lighting with motion sensors, solar water heating, and a 20 kWp photovoltaic system) and Stage 2 (deep envelope and system upgrade—Stage 1 plus triple-glazing, Variable Refrigerant Flow system, and a 17.5 kWp photovoltaic system). Predicted final (delivered) electricity intensity falls from 94.5 to 71.2 kWh/m²·y under Stage 1 (−24.7%) and to 63.3 kWh/m²·y under Stage 2 (−33.0%; 90% Monte Carlo uncertainty interval 59.0–70.4 kWh/m²·y), both well below the Palestinian Energy Building Code limit of 120 kWh/m²·y. On-site generation exceeds post-retrofit electrical demand under both stages, yielding a net-positive electrical balance. Direct carbon dioxide emissions fall by 6.84 t/y (−33%) at Stage 2. Discounted paybacks are 4.6 y (Stage 1) and 10.4 y (Stage 2), with internal rates of return of 24.7% and 11.7%. All proposed interventions received project-team consensus scores of ≥3/5 against EN 16883:2017 heritage-impact criteria. This study delivers a replicable simulation-based workflow for the energy assessment and heritage-compatible retrofit of thick-walled Palestinian stone buildings and one of the first field-informed heritage-retrofit datasets from the Levant. Full article

This paper investigates the thermal characteristics of machine tools under the influence of multiple heat sources and proposes an active temperature control method. The study was conducted under steady-state conditions with a constant feed rate of 10 m/min and no cutting load. First, finite element simulations are performed to analyze the thermal characteristics of the machine tool subjected to internal heat sources, yielding the corresponding temperature and deformation fields. Second, within the tested temperature range, the thermal characteristics are examined with respect to the layout of temperature control devices, and the best-performing layout schemes for the bed and column are determined. Subsequently, the thermal error resulting from the coupling effect of multiple temperature control devices is studied, and an active control strategy is proposed to obtain the best layout configuration within the tested range. Finally, experiments are conducted using a multi-loop differential active temperature control system, and the validity of the proposed method is verified through comparison between simulation and experimental results. The findings demonstrate that the proposed active control method effectively reduces thermal deformation in machine tool structures. Full article

Background: Nickel–titanium (Ni-Ti) instruments are continuously exposed to irrigating solutions during root canal preparation, which may affect their surface integrity. Evidence regarding the combined morphological and elemental effects of contemporary irrigation protocols on heat-treated single-file systems remains limited. This study evaluated the effects of different irrigation protocols on the surface morphology and elemental composition of Super One File Ni-Ti instruments using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Methods: Thirty Super One File instruments (size 25/.04) were randomly allocated to three groups: distilled water (DW), a sequential NaOCl–EDTA–NaOCl irrigation protocol (NEN), and a NaOCl/HEDP continuous chelation protocol. Instruments were continuously rotated in the assigned solution for 20 min. Surface morphology was assessed by SEM and elemental composition by EDS. SEM data were analysed using the Fisher–Freeman–Halton exact test, whereas EDS data were analysed using linear mixed-effects models with post hoc pairwise comparisons (α = 0.05). Results: SEM analysis revealed protocol- and region-dependent differences in surface alterations. The NEN group showed significantly higher corrosion and pitting frequencies than the DW group in selected regions, whereas no significant differences in these outcomes were detected between the NEN and HEDP groups. EDS analysis showed significant protocol × region interactions for all elements except Cl. These differences were most pronounced in the coronal region, where the HEDP group exhibited lower Ni and Ti and higher O, P, Na, and Ca levels than the DW and NEN groups. Conclusions: The tested irrigation protocols produced distinct, region-dependent surface responses in Super One File instruments, highlighting the potential influence of irrigation chemistry on Ni-Ti instrument surfaces under controlled experimental conditions. The clinical and mechanical implications of these alterations remain to be established. Full article