Search Results (281)

Luminescence thermometry has evolved through decades of research focused on optimising materials and on extracting temperature information from isolated spectral features such as luminescence intensity ratios, bandwidth, line shift and excited-state lifetime. Despite extensive material development, these conventional methods remain fundamentally limited by construction: only a small subset of pre-selected spectral features is exploited, while the bulk of the temperature-relevant information encoded in the full spectrum is systematically discarded. A paradigm shift is presented here: Luminescence Thermometry 2.0 (LT 2.0), implemented through the newly developed SpectraSensML platform, in which machine learning regression operates on the entire emission spectrum to deliver temperature readout. The approach is demonstrated on a Yb³⁺-doped phosphor emitting in the near-infrared biological transparency window across 100 to 700 K. Yb³⁺ is a particularly demanding case: only the single ²F_5/2 multiplet emits, and its weakly thermally coupled Stark sub-levels yield modest sensitivity under conventional intensity-ratio thermometry. A total of 27 regression algorithms drawn from four families, namely tree ensembles, physics-aware regression models, kernel and instance methods, and neural networks, are systematically benchmarked. A sensor-fusion estimator that combines the first three principal components reaches an average root-mean-square error of 0.36 K on an unseen-temperature test set, a seven-fold improvement over the best luminescence intensity ratio variant. Standard normal variate (SNV) normalisation is identified as the most effective preprocessing strategy because it isolates the band-shape deformations that encode temperature. Single-component approaches that rely on the first principal component alone are shown to be quantitatively sub-optimal: multi-component regressors that exploit the first three principal components reduce the temperature uncertainty by close to an order of magnitude. The structural reason behind the failure of decision-tree ensembles on unseen temperatures is explained: their piecewise-constant predictions cannot interpolate beyond training set-points. The open-source SpectraSensML application used to obtain the results is released alongside the manuscript to enable reproducible community benchmarks. Full article

This paper presents a critical review of surface protection strategies for refurbished hydropower components, with emphasis on the manufacturing and materials-processing logic that links damage mechanisms, substrate condition, deposition route, microstructure, and service performance. The literature indicates that cavitation erosion, sediment abrasion, corrosion, and their synergistic interactions are intensified by flexible and off-design hydropower operation, making refurbishment decisions increasingly surface-sensitive rather than purely bulk-material problems. Thermal spray and laser cladding remain the dominant industrially relevant routes, while cold spray and emerging multi-principal-element, high-entropy, and Fe-based amorphous systems expand the design space for lower heat input, better defect control, and improved cavitation resistance. Across the considered studies, the most consistent conclusion is that hardness alone is not a reliable selection criterion; porosity, interfacial integrity, crack susceptibility, residual stress, and the ability to accommodate local deformation govern real durability. Chemical pre-treatments, sealants, and hybrid finishing routes appear less mature as standalone hydropower solutions, but are important enablers for substrate activation, coating densification, and corrosion mitigation. Therefore, the review proposes a refurbishment-oriented framework in which route selection is based on the initial damage state of the component, the admissible thermal load on the substrate, the required build-up thickness, and the expected cavitation/slurry/corrosion regime. Full article

Geohazards in rock mass are essentially results of fracturing evolution. Regarding deeper exploration, to better contribute to evaluating and predicting instability, Particle Flow Code (PFC) has gained increasing popularity because of its logical resemblance in simulating rock composition and cracking processes. However, micro-parameter calibrations in PFC mainly focus on both the peak strength and macroscopic cracks in many previous, as well as current, studies, resulting in the existence of two widely used yet distinct strategies in stiffness calibration. The first is to ensure the consistency of the elastic modulus, and the second is to ensure the deformation consistency at peak-stress states. Do these two stiffness calibrations have a strength equivalence? To explore it, several rock mechanical tests—with and without confining pressures and a pre-existing flaw—were numerically conducted using PFC for two materials produced by these two distinct stiffness-calibration strategies. The results demonstrate that the two stiffness calibrations can yield equivalent strength parameters, including tensile strength, cohesion, and internal friction angle. This strength equivalence could be attributed to the evolutionary process of micro-crack initiation, accumulation, nucleation, and global failure (coalescence). Fracture mechanics analysis demonstrates that crack initiation is independent of the elastic modulus and marginally influenced by Poisson’s ratio, leading to a negligible impact of stiffness-calibration distinction on crack-initiation stress. Subsequent micro-crack accumulation follows a nearly identical non-linear increasing trend, with a high consistency of spatial distributions in stress concentration, displacement gradient, and strain localization. As a result, the near-identical structural logic in micro-crack nucleation results in failure-pattern consensus and governs the macro-scale strength equivalence of these two distinct stiffness-calibration strategies. These findings could help us to better comprehend those previous, as well as current, research results based on the two stiffness-calibration strategies. Full article

Nuclear infrastructure requires reliable gamma radiation shielding, for which heavyweight concrete offers a practical, structural solution. Conventional concrete provides poor gamma shielding and heat durability, demanding a denser alternative. Prior studies show that magnetite enhances attenuation and strength, while dolomite improves thermal/mechanical stability, yet findings are dispersed across materials and test conditions. Hybrid magnetite–dolomite concrete requires systematic evaluation for simultaneous optimal gamma shielding and mechanical performance under nuclear conditions. Two mixes were produced by partial replacement of coarse aggregate (Mix 1: 50% magnetite, 25% dolomite; Mix 2: 25% magnetite, 50% dolomite), casted and cured per standard practice with compressive strength measured at 7 and 28 days. Gamma attenuation was quantified using Cs-137 and Co-60. Mix 1 achieved 78.78% attenuation for Cs-137 and 76.86% for Co-60, while Mix 2 reached 77.65% and 74.68%, respectively. At 28 days, peak compressive strengths were 25.8 MPa (magnetite), 22.6 MPa (dolomite), and 20.6 MPa (control), with pre-peak energy capacity ranking as follows: magnetite > dolomite > control. Magnetite increased strength and attenuation but sharpened post-peak softening, whereas dolomite enhanced deformability and energy dissipation with minimal loss in shielding. Hybrid concrete satisfied shielding and strength targets and outperformed conventional concrete, with a magnetite-forward blend offering the best overall protection. Full article

Problematic subgrade soils degrade pavement performance, while conventional cement/lime stabilizers generate excessive carbon emissions. Unlike earlier reviews that focus on single-material systems—such as industrial by-products, alkali-activated binders for expansive soils, or geopolymers for pavement applications—an integrated framework spanning reaction mechanisms, microstructural evolution, engineering parameterization, and life-cycle validation is proposed The work offers three distinctive contributions: (i) a four-level evidence chain hierarchy (strength → microstructure → durability → leaching/LCA) to grade research completeness; (ii) repositioning resilient modulus, permanent deformation, and pore-connectivity evolution as core engineering outputs bridging material design and structural response; and (iii) a comparative assessment of alkali-activated geopolymers, low-clinker calcium-based composites, and multi-scale reinforcement strategies under consistent durability and environmental boundaries. Quantitative synthesis reveals the following: strength retention after 12 wet–dry/freeze–thaw cycles ranges from 60% to 85%; resilient modulus improvements over untreated soils reach 30%–120%, yet stress-dependent characterization remains essential; leaching concentrations of hazardous elements (Cr, Ba, Pb) can increase by 50%–200% after durability cycling if pore connectivity rebounds. Life-cycle carbon comparisons are boundary-sensitive—geopolymer advantages shrink from 60% to ≤20% when activator transport and pre-treatment are included. We conclude that the primary barrier to engineering adoption is not the absence of high-strength formulations, but the lack of extrapolatable design parameters and closed-loop evidence chains. A decision-support framework incorporating durability retention, leaching safety, carbon footprint, and field validation is proposed to guide robust design and industrial scaling. Critically, the review identifies that engineering adoption is constrained not by the absence of high-strength formulations, but by the lack of standardized construction protocols, quality control procedures, and long-term field performance data—gaps that must be addressed through coordinated field-scale demonstration projects. Full article

Hydrogen embrittlement (HE) is a critical issue that constrains the service reliability of structural alloys in hydrogen-rich environments. For the CoCrNi medium-entropy alloy (MEA), the interplay between deformation twins (DTs) and HE remains controversial, and the mechanism by which pre-strain-induced twin boundaries (TBs) influence hydrogen migration pathways and fracture behavior still requires further elucidation. To address this, the present study employed multiple complementary techniques, including slow strain rate tensile (SSRT) testing, electron backscatter diffraction (EBSD) analysis, direct hydrogen visualization via hydrogen microprinting (HMP), and microhardness measurements, to comparatively investigate the hydrogen-induced cracking behavior of the alloy subjected to pre-strain levels of 0%, 30%, and 50%. Experimental results reveal that dense nanoscale TBs can serve as both effective hydrogen trapping sites and diffusion barriers, substantially modifying the hydrogen distribution pattern and preventing substantial hydrogen enrichment at grain boundaries (GBs). This twin-dominated regulatory mechanism significantly suppresses hydrogen-induced intergranular fracture, endowing the material with outstanding HE resistance. These findings elucidate the intrinsic anti-HE mechanism governed by twin structures and provide a microstructural design basis for the development of high-performance hydrogen-resistant multi-principal element alloys (MPEAs). Full article

Coal has abundant bedding and joint structures, and most of it exhibits obvious brittle characteristics, which leads to its easy cracking and failure under mining stress. This easily leads to slab cracking and roof collapse in coal mining faces, as well as large deformations in roadways. On-site grouting of fractured coal bodies can effectively prevent these disasters. To reveal this mechanism, this study has first developed a modified ultra-fine cement grouting material and high-pressure continuous grouting system, and then conducted grouting and uniaxial compression tests on post-peak coal samples. Test results indicate that the post-peak residual bearing capacity of grouted coal specimens can recover to 65~85% of the peak strength of intact raw coal. The pre-peak plastic deformation becomes significant, and the post-peak stage exhibits stable strain softening. Grouting is considered to serve to improve the internal stress state of coal samples, act as a ductile grid skeleton, coordinate their internal deformation, and enhance their post-peak bearing capacity. Full article

The particular microstructure of hot-deformed Nd-Fe-B magnets leads to difficulties in finding a direct recycling route. In this work, a combination of field-assisted sintering technology/spark plasma sintering (FAST/SPS) and spark plasma texturing (SPT) is used as pre-compaction and deformation techniques, respectively, for the consolidation of crushed, hot-deformed Nd-Fe-B scrap. Field-assisted sintering has the unique advantage of maintaining fine microstructures during material densification, making it an ideal candidate for direct recycling of this material. Recycled magnets, made from 100 wt% crushed magnet scrap, were able to achieve energy products of over 200 kJ m⁻³ after FAST/SPS pre-compaction and SPT deformation. These recycled magnets could then be smoothed and cut to the size of industrial bar magnets for testing in the motor of a water pump. When tested, the recycled magnets could achieve 95% of the electromotive force compared to industrial standard magnets. Full article

Cleft lip with or without cleft palate (CL/P) is one of the most common congenital craniofacial anomalies worldwide and presents significant functional, esthetic, and psychosocial challenges. Despite advances in multidisciplinary care and surgical reconstruction, complications such as impaired wound healing, scar formation, and growth disturbances warrant the development of novel regenerative and surgical strategies, which heavily rely on animal models at the pre-clinical stage. For the current narrative review, the literature search was performed by combining cleft phenotype terms with modeling-approach terms in six databases and was supplemented by manual review of reference lists from full-text articles. The included articles were summarized based on cleft type and the methods for cleft induction (chemically induced, genetically engineered, and surgically created). Particularly, chemical teratogens such as retinoic acid, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), corticosteroids, and 6-aminonicotinamide have been widely used to induce cleft phenotypes and elucidate environmental influences on palatogenesis, whereas genetic models have clarified the roles of key molecules and signaling pathways, including Sonic hedgehog (SHH), bone morphogenetic protein (BMP), and transforming growth factor-β (TGF-β), in the development of lip and palate. Meanwhile, the surgical models have focused on the alveolar cleft in skeletally mature animals for evaluating novel grafting materials. By comparing the strengths and limitations of existing models, this review highlights opportunities for improving experimental design and translational relevance in future cleft research. Overall, despite a wide range of CL/P animal models available, few replicate clinically relevant defect anatomy and the postnatal craniofacial deformation observed in CL/P patients, underscoring the need for the development of new models. Full article

Brittle geomaterials such as coal and rock are prone to unstable failure under high stress and dynamic disturbances, where rapid release of stored elastic strain energy can trigger dynamic disasters. Polyurea, a high-strength and high-ductility elastomer, can form a continuous flexible coating on the surface of coal/rock to regulate their deformation–fracture behavior. Here, uniaxial compression tests were performed on coal specimens coated with polyurea layers of different thicknesses (0–1.25 mm). Acoustic emission (AE) and digital image correlation (DIC) were jointly employed to characterize macroscopic deformation, microcrack evolution, fracture-mode transition, and energy partitioning. The results show that polyurea provides passive lateral confinement that suppresses lateral expansion and shifts macroscopic failure from brittle splitting to progressive ductile damage. AE-based AF–RA analysis indicates that thicker coatings increase the normal stress and shear resistance along potential fracture planes, promoting a microfracture transition from shear-dominated to tension-dominated cracking. Energy analysis demonstrates that the coating enhances pre-peak energy dissipation via coordinated deformation with the coal, while thicker coatings (≥1.00 mm) exhibit pronounced post-peak elastic tensile deformation to absorb and buffer fracture-released energy, impeding the instantaneous energy release typical of bare coal. Moreover, the elastic energy index shows that polyurea markedly reduces impact tendency, with an appropriate thickness stabilizing specimens from strong to weak/non-impact propensity. These findings clarify the coupled confinement–fracture–energy regulation mechanisms of polyurea coatings and provide quantitative guidance for coating-thickness design to mitigate dynamic failure hazards in brittle materials. Full article

This contribution presents a simulation-based approach for optimizing injection molding processes using digital twins. It combines surrogate modeling via response surface methodology (RSM) with the evolutionary algorithm NSGA-II to efficiently capture complex relationships between process parameters and objectives. A key element is the adaptive enhancement of the training dataset within the decision-relevant region of interest (ADEROI) by a modified greedy max–min algorithm. This strategy closes data gaps, improves model accuracy in the potentially optimal region, and directs additional simulations to informative areas. Leave-one-out (LOO) and hold-out (HO) cross-validations show strong root mean square error (RMSE) and $R^2$ values for deformation, shrinkage, cycle time, and mass. NSGA-II converges after 403 generations and results in 191 Pareto-optimal solutions, which are consolidated into preference-consistent operating points. These points make trade-offs between analyzed objectives’ deformation, shrinkage, and cycle time explicit for process pre-design. Preferred solutions are identified through weighted sums of normalized objectives and inversely mapped process parameters. Their agreement with the physics-based digital twin at the hundredths level supports the plausibility of the selected operating points within the investigated simulation-based workflow. A retrospective benchmark against a scaled single-stage LHS baseline shows that ADEROI achieves ROI-equivalent point density with fewer simulation runs for the investigated case, reducing the estimated runtime by $39.1\%$ and resulting in a $1.64\times$ speed-up. The quantitative validation is limited to one thin-walled PP keyholder component; further geometries, mold layouts, and polymer materials are required to empirically assess generalizability. Full article

Marine transportation and storage of liquid hydrogen (LH2) has gained increasing interest, while potential LH2 membrane-type tanks could utilize 316L corrugated austenitic stainless-steel sheets. The corrugation process results in a strain-induced martensitic transformation in the material, introducing rapid diffusion pathways for hydrogen atoms and promoting the formation of hydrogen-trapping sites that alter hydrogen transport and reduce the material’s resistance to hydrogen embrittlement. In this study, 316L sheets were subjected to different levels of uniaxial pre-strain (10, 20, 30, and 40%) with two different strain-rates, to replicate the varying degrees of pre-deformation caused by the corrugation. Microstructural analysis using Electron Backscatter Diffraction (EBSD) (Thermo Fisher Scientific, Waltham, MA, USA) and X-Ray Diffraction (XRD) (Bruker, Billerica, MA, USA) combined with quantitative phase analysis using the Rietveld Method on XRD data, provided valuable insights into the induced phase transformations. Cathodic hydrogen charging method was implemented on as-received and pre-strained material, followed by slow strain rate tensile testing (SSRT) and thermal desorption spectroscopy (TDS) to examine the hydrogen effect on each condition. Experimental results indicated that although 316L exhibits considerable phase stability, it undergoes strain-induced phase transformation resulting in a significant amount of martensite, reaching 5% in the 40% pre-strained condition. Pre-deformation increased hydrogen embrittlement, as evidenced by fractographic analysis which indicated a Relative Reduction of Area (RRA) of 0.83, and by increased hydrogen uptake. These findings contribute to a better understanding of phase transformations and the role of hydrogen in austenitic stainless steels. Full article

Advanced pultrusion technology for composite materials is an automated forming process that uses pre-impregnated materials as raw materials and is oriented towards the manufacturing of continuous components. It is particularly suitable for the continuous manufacturing of ultra-long components with uniform cross-sections and has a promising application prospect in the field of aviation composite materials. However, during the preforming stage, the pre-impregnated materials are prone to strain concentration and uneven thickness under the constraint of the mold surface, and in severe cases, there is a tendency to form wrinkles. Moreover, the severity of these defects is further influenced by the process parameters. In response to the above problems, this paper proposes a mold surface optimization method based on the finite element model with the goal of three-dimensional strain homogenization, which controls the thickness direction and in-plane strain within 5%, effectively improving the material deformation coordination. Furthermore, the influence law of preforming temperature, traction speed and tension on preforming quality was systematically analyzed through experimental research. It was found that the influence of each process parameter on appearance quality, thickness uniformity and internal quality all showed a trend of “improvement first and then deterioration”, thus obtaining a relatively better combination of process parameters for preforming quality. The results of this study provide methodological and technical support for the research on advanced pultrusion preforming processes of complex cross-section components. Full article

Fused filament fabrication (FFF) produces components with characteristic topographical features that influence their tribological behavior. Because conventional roughness parameters may not fully describe the localized surface degradation of reinforced FFF polymers, this study evaluates the wear-track evolution of FFF aramid fiber-reinforced Acrylonitrile Styrene Acrylate (ASA) composites using a comparative profilometric framework based on pre-wear and post-wear measurements. Specimens with different infill configurations underwent dry sliding Ball-on-Disc tribological testing, followed by profilometric wear-track analysis and optical microscopy inspection. The macroscopic wear response exhibited a non-monotonic dependence on infill configuration. Under the present experimental conditions, the 30% infill configuration showed the most favorable average wear response, with the lowest wear volume and specific wear rate, whereas the 90% infill configuration showed the highest material loss. To compare the surface modifications induced by sliding, three derived relative profilometric descriptors were evaluated: Surface Texture Alteration Index (STAI), Peak Deformation Index (PDI) and Material Ratio Preservation Index (MRPI). These descriptors were used as complementary comparative parameters rather than replacements for standardized roughness or Abbott–Firestone-based measurements. Statistical analysis showed a very strong association between maximum wear-track depth and calculated volumetric material loss, indicating that deeper wear-track profiles were consistently associated with higher material removal within the investigated dataset. Furthermore, correlation analysis suggested that the initial material ratio may be more closely associated with the subsequent wear response than the initial arithmetic mean roughness. This study indicates that combining wear volume, wear-track geometry, optical microscopy and relative profilometric descriptors provides a useful comparative approach for evaluating degradation in FFF Kevlar-reinforced ASA components under sliding conditions. Full article

Background and Objectives: Adolescent idiopathic scoliosis (AIS) may influence pelvic orientation and lower-limb alignment; however, data on coronal lower-limb alignment after completion of spinal treatment remain limited. This study aimed to evaluate lower-limb radiographic alignment in AIS patients after spinal treatment and to determine whether these parameters differ according to main curve location. Materials and Methods: In this retrospective study, 70 AIS patients treated surgically (n = 52) or with brace therapy (n = 18) between 2010 and 2020 were analyzed. Patients were grouped according to main curve location as thoracic (n = 28), lumbar (n = 21), or thoracolumbar (n = 21). Pre-treatment standing full-spine radiographs were used to assess Cobb angle, coronal balance, and pelvic coronal obliquity angle (PCOA). After completion of spinal treatment, full-length weight-bearing lower-limb radiographs were evaluated for femoral and tibial lengths, mechanical axis deviation (MAD), femoral neck–shaft angle (NSA), anatomical lateral distal femoral angle (aLDFA), and mechanical lateral distal femoral angle (mLDFA). Additional treatment-stratified, treatment-adjusted, and threshold-based analyses were performed. Results: PCOA, coronal balance, bilateral MAD, right aLDFA, and right mLDFA differed significantly among the three curve-location groups. The lumbar group demonstrated more negative MAD values than the thoracic group, indicating a tendency toward valgus alignment (right MAD: −5.88 ± 8.8 mm vs. 3.65 ± 7.9 mm, p = 0.004; left MAD: −3.5 ± 7.5 mm vs. 3.75 ± 7.0 mm, p = 0.005). After adjustment for treatment modality, age, and main Cobb angle, curve location remained significantly associated with right MAD, left MAD, right aLDFA, and right mLDFA. However, the proportion of patients with clinically relevant malalignment, defined as MAD exceeding ±10 mm in at least one limb, did not differ significantly among the groups. Conclusions: AIS patients show subtle but measurable differences in coronal lower-limb alignment after completion of spinal treatment. Lumbar and thoracolumbar curves are associated with greater pelvic obliquity and a tendency toward more valgus mechanical-axis alignment, whereas limb lengths and NSA remain comparable among curve-location groups. These findings appear to represent mainly radiographic or biomechanical variations rather than overt clinically relevant deformity in most patients. Full article