Search Results (2,886)

Accurate 3D topography measurement of micro-structured surfaces remains challenging due to the limitations of conventional autostereoscopic systems, particularly the intrinsic constraints of light-field imaging and dependence on single-source data. Building on a multichannel autostereoscopic measurement system that simultaneously captures a high-resolution (HR) 2D center view containing rich textural and edge information and a light-field image providing dense multiview geometric cues, a deep learning-enhanced feature fusion network is introduced. This model is a hybrid deep learning architecture featuring a convolutional local feature extractor for the HR image, a Transformer-based global feature extractor for angular relations in the light field, and a cross-channel attention fusion module for effective feature integration. The end-to-end trainable network is optimized using a composite loss function. Experiments on synthetic and real micro-structured surfaces demonstrate stable performance of the proposed approach, achieving improved accuracy and stability over current depth-estimation methods in challenging micro-scale scenarios. Full article

Against the backdrop of global green and low-carbon development, recycling industrial solid waste for building-material applications attracts increasing attention. In this work, a composite solidifier (SGPC) was prepared using soda residue (SR), ground-granulated blast-furnace slag (GGBS), phosphogypsum (PG) and Portland cement. Fluidized solidified soil was produced by incorporating 15% recycled concrete aggregate (RCA). Chemical-erosion tests including strong-acid, strong-alkaline and neutral-sulfate corrosion were carried out. Mass-loss-rate and unconfined-compressive-strength-loss-rate measurements at different exposure ages, combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterisation, were adopted to investigate the macroscopic durability, hydration-product phases and microstructural features of RCA-modified solidified soil. The test results show that under acid corrosion, the 120 d strength-loss rate decreases from 19.86% (RCA-free group) to 9.02% for specimens containing 15% RCA. Under alkaline corrosion, the 120-d mass-loss rate of the RCA-modified group reaches only 0.33%, much lower than 1.46% of the group without RCA. Under sulfate corrosion, the 120-d strength-loss rate drops from 5.65% to 2.02% after RCA addition. This work provides experimental data and theoretical support for the joint utilisation of multi-source solid waste and recycled aggregates in soil-solidification engineering. Full article

Coastal saline soils are vulnerable to degradation under repeated wetting–drying (W–D) exposure, while conventional inorganic stabilizers are associated with high energy consumption and environmental burdens. To address this issue, an environmentally friendly ternary stabilization system consisting of local sandy silt, low-dose cement, and xanthan gum (XG) at different dosages was developed, with emphasis on the particle-scale coating effect of hydrated XG. Accelerated laboratory W–D cycling (0–20 cycles), direct shear tests, unconfined compressive strength (UCS) tests, binary-image crack analysis, and field-emission scanning electron microscopy (FE-SEM) were used to evaluate the effects of W–D cycling and XG dosage (0%–2.0%) on mechanical properties, interfacial bonding, surface deterioration, and microstructural evolution. An optimum XG dosage of 1.5% was identified. Before W–D cycling, the UCS of the 1.5% XG group reached 1005.4 kPa, 94.9% higher than that of the 0% XG control. After 20 W–D cycles, the 1.5% XG group exhibited a mass loss rate of 3.7%, a crack ratio below 4.3%, and a compressive strength retention of 83.8%, whereas the 0% XG control showed more pronounced mass loss and strength degradation. The XG coating limited water and salt migration and provided flexible interparticle bridging that mitigated shrinkage-induced stress concentration. FE-SEM observations further indicated that XG and cement hydration products formed a relatively continuous organic–inorganic interfacial network, which helped preserve particle contacts and restrain microcrack propagation during cyclic exposure. These results demonstrate the potential of particle-scale XG coating for improving the W–D durability of modified saline soil. Full article

Converting waste slurry from underground construction into foamed lightweight soil (FLS) offers a route to waste valorization, but its durability under repeated moisture changes requires evaluation. This study compared FLS prepared with ordinary Portland cement (OPC), alkali-activated slag–fly ash (AASF), and hybrid OPC-AASF. Engineering properties and resistance to 18 wetting and drying (W-D) cycles were evaluated alongside pore structure evolution, microstructural changes, and environmental and economic indicators. Increasing soil content reduced unconfined compressive strength (UCS), with OPC-AASF showing a more gradual decline than OPC. All systems exhibited non-monotonic strength evolution during cycling. After 18 cycles, the UCS losses relative to the 28 d baseline were 1.9%–5.8% for OPC-AASF and 12.3%–17.6% for AASF. In selected specimens, X-ray computed tomography showed that lower macroporosity did not necessarily correspond to better strength retention. The greater strength loss in AASF was accompanied by spatial pore enrichment, coarse low-sphericity pores, and local interfacial damage. X-ray diffraction indicated retention of the main crystalline phases, while scanning electron microscopy showed better local pore wall and interfacial continuity in OPC-AASF. On a common dry-solids mass basis, the hybrid mixture containing 40% soil required 76.0% less OPC than a theoretical OPC foam concrete without waste soil. The estimated carbon emissions, energy intensity, and material cost associated with raw material inputs were 72.2%, 68.0%, and 48.1% lower, respectively. These findings support OPC-AASF as a cement-reduced stabilization system for lightweight backfill, combining waste slurry reuse with strength retention under repeated moisture fluctuations. Full article

This article examines the reuse of waste polyurethane foam (PUF) as a material in line with circular economy principles. The main objective was to evaluate how crushed polyurethane filler of different bulk densities—35 kg·m⁻³ (PUF35), 60 kg·m⁻³ (PUF60), and their blends at 1–5 wt%—affects the mechanical behaviour and structural integrity of hybrid composite systems and bonded laminated joints. An epoxy resin matrix was combined with 3D-printed polylactide (PLA) honeycomb structures, with rectangular and hexagonal core geometries. Static tensile tests showed that the blended filler (PUF35/60) preserves tensile strength and increases the modulus of elasticity for both core geometries, reaching maximum values at 4 wt% (3.8 GPa for rectangular, 3.6 GPa for hexagonal cores). In bonded lap joints, 1 wt% PUF35 resulted in the highest tensile adhesive bond strength (13.3 MPa). SEM confirmed a high-quality phase interface and continuous adhesive contact between the epoxy matrix and the 3D-printed PLA surface, with dominant cohesive failure and effective mechanical anchoring of foam particles, even near local printing defects. The results confirm mechanically recycled PUF as a promising filler for advanced sandwich structures and adhesive systems. Full article

Water-based drilling cuttings (WBDCs) are a large-volume solid waste generated during oil and gas drilling. Their weak cementation and loose particle structure limit their direct engineering utilization. In this study, a multi-source solid-waste binder mainly composed of ground granulated blast furnace slag (GGBS) and fly ash (FA) was used to stabilize WBDCs. Portland cement was used as an auxiliary binder, and sodium silicate was used as the alkaline activator. The effects of sodium silicate modulus, sodium silicate dosage, cement dosage, and GGBS-to-FA mass ratio on strength development were investigated. XRD, FTIR, TG, MIP, and SEM-EDS were further employed to clarify the stabilization mechanism. The results showed that binder composition strongly affected the strength level and strength development rate of stabilized WBDCs. At a total binder dosage of 15%, the mixture with a sodium silicate modulus of 1.4, a sodium silicate dosage of 4%, a cement dosage of 10%, and a GGBS-to-FA mass ratio of 6:1 exhibited the best mechanical performance. Its unconfined compressive strengths reached 6.87, 9.74, and 10.17 MPa at 7, 14, and 28 d, respectively. Microstructural analyses indicated that the strength development of stabilized WBDCs was mainly associated with the formation and continued development of poorly crystalline C-S-H/C-(A)-S-H-type gels and a small amount of AFt. From 7 to 28 d, the porosity and total pore volume decreased by 9.5% and 11.0%, respectively, while the average pore diameter decreased by 31.2%. This study provides a basis for the resource utilization of WBDCs and the design of low-cement binders containing multiple industrial solid wastes. Full article

Bio-based alternatives to conventional rigid foams have proven to be good substitutes owing to their enhanced sustainability and competitive performance. However, because their manufacturing processes are complex and destructive testing is often impractical, this study investigates whether microstructural features can be correlated with mechanical properties in lignin-containing rigid polyurethane (PU) foams using machine learning approaches. Various types and percentages of lignin-based polyols were investigated as partial replacements for polyol, including LHO, DCA, DCA-D, LHO-O, Kraft lignin (KL), and LHO-MD, at polyol replacement levels ranging from 12.5% to 50%, together with a control formulation. Scanning electron microscopy (SEM) images and corresponding mechanical compression data were used to train a custom state-of-the-art dual-head convolutional neural network (CNN) targeting the specific prediction of density, specific compression modulus, specific yield stress, and specific compression strength. The CNN was optimized with a weighted multi-output loss function, achieving strong predictive performance with R² values ranging from 0.850 to 0.91 and correlation coefficients above 0.92, while maintaining mean absolute error percentages below ≈9%. This proves the trained network’s capability to predict and capture morphological features governing load-bearing responses. On the other hand, Grad-CAM visualization revealed that the network focused its predictions on physically meaningful microstructural regions such as cell walls and strut junctions, which confirms that the proposed network can be classified as an interpretable, non-destructive, and data-driven framework for predicting and understanding bio-based PU foams’ mechanical behavior, hence reducing the inconvenience caused by time-consuming manufacturing and destructive testing. Full article

Waste-to-hydrogen technology requires the involvement of new material development and performance evaluation for additive manufacturing (AM). Metal 3D printing is a very good possible alternative and is delivering results visible in the circular-economy environment. By using the AM technique, complex operations are avoided when combining the individual components, which is a typical disadvantage in obtaining composite materials; such samples are prepared with only one operation from the starting melt, which is chemically defined. Pyrolysis rotary kiln sealing rings are to be upgraded with several different microstructure coatings in order to improve the surface performance. The surface topology is aimed to be fine, dense and smooth. Also, the target characteristics are a low friction coefficient and a high hardness value, suggesting enhanced wear resistance. For elevated temperatures, 900 °C is selected for cobalt-based superalloy Stellite types with particle reinforcement. Two possibilities for advanced materials production are proposed with the Directed Energy Deposition Plasma Arc (DED-arc) and Laser Directed Energy Deposition (DED-LB). The shell of the rotary kiln sealing ring is made of stainless steel as the base, with the coating overlaid. Selected mixtures in powder form with defined composition are applied. For the DED-arc, commercially available Stellite 6 (Deloro Stellite^® 6) and 20 vol% WC particles with a grain size of 63–150 µm were employed. For the DED-LB, we employed TRIBALOY^® T-800 (Kennametal Stellite^TM) with 25 vol% TiC and a mesh size of −100/+325 (particle diameter between 45 and 150 µm). After the representative samples were metallurgically bonded with the base stainless steel, the relevant properties were obtained. Manufactured samples are compared in terms of microstructures and mechanical properties. Analysis of structure: Intermetallic carbides that formed on the cobalt basis make the composite harder and increase the plasticity in a defined direction. The hypoeutectic structures of Stellite 6 + 20% WC consist of dendrite and interdendrite eutectic. It is observed that with an increase in WC volume fraction, the size of the dendrites becomes finer, and the amount of eutectic structure is increased. For the TRIBALOY^® T-800 with TiC, we obtained relatively smaller grain sizes. The roughness values for the tested samples with WC were initially Ra = 0.8 µm, increasing up to Ra = 3.44 µm after the wear test, whereas for the TiC, they were slightly lower. Microhardness testing revealed increased values compared to the base stainless steels. Advanced sensor analysis with acoustic emission (AE) and electrical contact resistance (ECR) also showed the properties of the new materials. Customizable coatings with tailored properties were deposited by DED-arc and DED-LB. From the tests performed, a new technological procedure for the production of novel pyrolysis rotary kiln sealing rings is proposed. The microhardness, roughness, microstructure and abrasive wear-resistant response of the metallic composite material were examined in order to characterize the stable multiphase system. Full article

To improve fly ash utilization in mine grouting materials and address the slow reaction and limited early-age strength of fly ash-based binders, a fly ash-based grout was prepared using fly ash and S95-grade ground granulated blast-furnace slag at a mass ratio of 70:30 and activated with NaOH-Na₂SO₄. A full-factorial experiment evaluated the effects of water-to-solid ratio, total activator dosage, and NaOH:Na₂SO₄ on fluidity, bleeding rate, stone formation rate, and compressive strength at 7 and 28 d. Representative 7 d specimens were characterized by SEM, EDS, and XRD. Increasing the water-to-solid ratio improved fluidity but increased the bleeding rate and reduced the stone formation rate and compressive strength. The preferred mixture had a water-to-solid ratio of 0.55, a total activator dosage of 5%, and NaOH:Na₂SO₄ = 2:1. It exhibited a fluidity of 195.0 mm, a bleeding rate of 1.70%, a stone formation rate of 99.50%, and compressive strengths of 8.5 MPa at 7 d and 11.3 MPa at 28 d. At NaOH:Na₂SO₄ = 2:1, the specimen showed a denser microstructure with fewer pores and cracks, a local Ca/Si ratio of approximately 0.94, and more evident reaction-product features. The results provide an experimental basis for mix-proportion selection of fly ash-based grouting materials. Full article

Bread texture and flavor are largely governed by the development of its internal microstructure and the migration dynamics of water and volatile compounds. In this study, a bamboo shoot shell superfine powder/κ-carrageenan composite gel system (KCS) was developed, and the effects of different addition levels (0%, 5%, 10%, 15%, 20%) of KCS on bread performance, structure, and flavor were investigated. Compared with κ-carrageenan (KC), KCS formed a denser and more continuous composite network structure with higher elasticity, freeze–thaw stability, and thermal stability. Bread with KCS showed improved color, reduced hardness, and chewiness. Electronic nose and tongue indicated that KCS effectively suppressed the release of undesirable volatiles and taste-active substances. The addition of 10% KCS promoted the formation of a uniform fine honeycomb gluten network structure, inhibited starch retrogradation, and improved the thermal stability of bread. During storage (1–5 d), KCS reduced the water loss rate of bread, delayed the increase in hardness and chewiness, and maintained good springiness. Metabolomic analysis showed that KCS increased the precursors of small peptides involved in the Maillard reaction, thereby enriching flavor. KCS can effectively improve bread quality, enrich bread flavor, and delay aging, providing a new strategy for the high-value utilization of bamboo shoot processing by-products. Full article

Digital fabrication with concrete enables manufacturing of geometrically complex and individualized elements, increasing the need for scalable non-destructive quality-control methods. This study is a preliminary investigation of the ultrasonic pulse velocity (UPV) use for shotcrete 3D-printed (SC3DP) concrete, with a particular focus on material variability caused by changes in the key manufacturing parameters, i.e., nozzle traverse speed and distance, as well as air volume flow and concrete pump speed. A series of small SC3DP specimens was produced using different manufacturing parameters settings. UPV was first measured transversely, across a single layer. Cores were then extracted, and UPV was measured axially through multiple layers before compression testing. The results showed a good correlation between UPV and bulk density but only a weak relationship between UPV and compressive strength. Pulse velocities measured across a single layer were lower than those measured through multiple layers, indicating direction-dependent wave propagation different to what is known from extrusion-based concrete 3D printing. Subsequently, UPV measurements were performed on two full-scale wall elements. The wall elements exhibited very low spatial variability in UPV, although their absolute velocities were lower than those measured for the small specimens. Overall, UPV appears promising for relative quality and homogeneity assessment of SC3DP elements, but further systematic research is required to clarify its relationships with microstructure and mechanical properties imposed by variation of manufacturing parameters. Full article

The relationship between two-phase flow behavior and pore microstructure in low-permeability gas reservoirs remains poorly understood, particularly during gas accumulation (gas displacing water) and subsequent development (water displacing gas). To address this, five plug cores with permeabilities ranging from 0.02 to 20.92 mD were selected from a low-permeability sandstone gas reservoir in the Tarim Oilfield. A comprehensive experimental program was carried out, including pore-throat structure characterization, wettability measurements, and both steady-state and unsteady-state gas–water relative permeability tests. These data were further integrated with capillary pressure curves derived from high-pressure mercury injection, centrifugation, and semipermeable membrane methods, enabling systematic comparison and parametric modeling. The results indicate that the reservoir is generally characterized by low permeability, fine pore throats, and moderate water-wetness, with contact angles between 49° and 60°. As permeability declines, pore-throat dimensions decrease and pore connectivity worsens: the mercury injection saturation median pressure increases from 0.752 to 16.477 MPa, while mercury withdrawal efficiency drops from 78.59% to 40.54%. These trends suggest that finer throats impose greater resistance to nonwetting phase invasion and that the “ink-bottle” effect intensifies fluid entrapment. Relative permeability measurements show that the unsteady-state method is more responsive to gas breakthrough and localized flow channeling, yielding lower endpoint gas relative permeability compared to the steady-state approach. With deteriorating reservoir quality, irreducible water saturation during gas displacement rises from 29.03% to 45.20%, residual gas saturation during water displacement increases from 17.60% to 38.90%, and the two-phase coexisting flow zone narrows markedly from 53.37% to 15.90%. The consistent trends observed between relative permeability and mercury injection data confirm that reduced pore-throat size and heightened capillary resistance not only hinder the formation of continuous nonwetting phase pathways but also promote water retention and gas trapping. Through normalization, representative Corey-type gas–water relative permeability curves were established for the study area (with Corey exponents of 2.393 and 1.534 for the gas and water phases, respectively, under gas-displacing-water conditions), along with Brooks–Corey-type capillary pressure curves (with equivalent displacement pressures ranging from 0.025 to 0.133 MPa). These results provide essential parameters for seepage characterization and numerical simulation of underground gas storage in low-permeability gas reservoirs. Full article

Particle-reinforced metal matrix composites, wherein preform pore structure dominates liquid infiltration behavior and final composite quality, are essential for high-performance industries. Conventional empirical models predict pore characteristics for bimodal preforms based on ideal particle stacking assumptions yet ignore real compression-induced microstructural changes including particle contact compaction and particle fracture, yielding systematic deviations from actual pore characteristics. This study adopted high-resolution 3D X-ray micro-computed tomography (μ-CT) to quantify such discrepancies for bimodal SiC_p preforms across six coarse-to-fine particle ratios (0–100%). Three-dimensional pore network models were extracted to quantify key characteristics including areal porosity, surface area, and pore/throat dimensions. The results demonstrated that the average areal porosity fell to a minimum at a 67% coarse fraction then rose, while the pore distribution homogeneity steadily declined. Additionally, μ-CT measurements revealed that particle contact compactness reduced the particle surface area per unit volume at coarse fractions below 25% whereas particle fracture increased it at fractions above 25%, deviating significantly from empirical predictions. Larger coarse particle fractions reduced pore/throat quantities but increased their average size and volume. Beyond using established pore network extraction, this work distinguishes these two competing micro mechanisms and provides reasonable datasets to support bimodal preform optimization for composite manufacturing. Full article

This study investigated and optimized the operational process parameters of an extrusion-based 3D food printing system to maximize the dimensional fidelity of newly developed Wolffia globosa (duckweed) starch hydrogel constructs relative to a nominal target specification of 30 × 30 × 30 mm. Prior to parameter optimization, synchrotron X-ray tomographic microscopy (SR-XTM) was used to characterize Wolffia globosa particle size and dispersion within the starch matrix, showing that grinding eliminated large particle agglomerates (up to approximately 150 µm) and was necessary for smooth, continuous extrusion; the ground formulation was accordingly selected for all printing trials. A full factorial experimental configuration was executed to examine the synchronized effects of three core process parameters: print-head traverse speed (5–15 mm/s), extrusion speed (5–15 steps/mm), and layer height (1.9–3.7 mm). Experimental responses were evaluated via Three-Way Analysis of Variance (ANOVA) and Response Surface Methodology (RSM) using triplicate measurements (n = 3) at each of the 27 tested parameter combinations. Residual diagnostics indicated an approximately normal distribution for the height model (Shapiro–Wilk p = 0.716), whereas the width and length models showed some departure from normality (p < 0.01), consistent with the significant lack-of-fit detected for these two responses. Three-way ANOVA confirmed that print-head (nozzle) speed was the dominant factor governing the in-plane dimensions (width and length; partial η² ≈ 0.98), while height was jointly governed by all three factors, with layer height and print-head speed contributing the largest effects. With the statistical power afforded by replicate measurements, all two- and three-way interactions among the three factors were also statistically significant for width and length (p < 0.001), refining the single-replicate interaction pattern reported previously. Empirical second-order polynomial equations explained a substantial share of the variance in each dimension (R² = 0.70–0.85), although formal lack-of-fit testing indicated that higher-order interactions not captured by the quadratic terms remained statistically significant, and the equations should therefore be interpreted as descriptive rather than as precise predictive tools. Based on the triplicate means, a print-head speed of 5 mm/s, extrusion speed of 15 steps/mm, and a layer height of 1.9 mm minimized the mean cumulative absolute error to 4.01 mm, yielding a mean dimensional profile of 28.63 ± 0.78 mm width, 27.76 ± 0.96 mm length, and 30.41 ± 0.70 mm height (mean ± SD, n = 3). Full article

Background/Objectives: Cerebral small vessel disease (SVD) is a heterogeneous condition in which similar conventional MRI findings may be associated with different clinical manifestations and pathogenetic mechanisms. Previously, hierarchical clustering of structural MRI features in patients with severe white matter hyperintensities (Fazekas 3) identified two MRI phenotypes, designated MRI Type 1 and MRI Type 2. Diffusion MRI (dMRI) may provide additional information about the microstructural differences between these phenotypes. To compare white matter microstructure between MRI Type 1 and MRI Type 2 of sporadic age-related SVD using signal-based and biophysical dMRI models. Methods: This cross-sectional study included 75 patients with SVD and 36 age- and sex-matched healthy controls. Among the patients with SVD, 43 had MRI Type 1 and 32 had MRI Type 2. All participants underwent structural and multi-shell dMRI on a 3 Tesla MRI scanner. Diffusion metrics were derived using multiple models: Diffusion Tensor Imaging (DTI), Diffusion Kurtosis Imaging (DKI), Neurite Orientation Dispersion and Density Imaging (NODDI), White Matter Tract Integrity (WMTI), and the Multi-compartment Spherical Mean Technique (MC-SMT). Tract-profile analysis was performed in three corpus callosum segments: the forceps major, forceps minor, and body. Group differences were assessed using age- and sex-adjusted general linear models with correction for multiple comparisons. The combined discriminative value of dMRI metrics was evaluated using regularized Elastic Net logistic regression with repeated nested five-fold cross-validation. Results: After adjustment for age and sex, the overall group effect remained significant for 45 of 48 global dMRI measures following Benjamini–Hochberg correction. Compared with MRI Type 2, MRI Type 1 showed lower fractional anisotropy (FA), neurite density index (NDI), intra-axonal volume fraction (INTRA), axonal water fraction (AWF), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK), and higher mean diffusivity (MD), radial diffusivity (RD), extra-axonal mean diffusivity (EXTRA_MD), extra-axonal transverse diffusivity (EXTRA_TRANS), and extra-axonal radial diffusivity (radEAD). These differences were generally most pronounced in the body of the corpus callosum. In the segmental analysis, 131 of 144 values showed a significant overall group effect after correction, and 108 demonstrated significant differences between MRI Type 1 and MRI Type 2. The largest effects were observed in the 60–80% interval of the corpus callosum body, particularly for AWF, MK, INTRA, EXTRA_TRANS, RK, FA, RD, radEAD, and MD. An Elastic Net model combining age, sex, and 48 global dMRI measures discriminated MRI Type 1 from MRI Type 2 with an internally validated area under the curve of 0.866 (95% CI, 0.762–0.953), accuracy of 86.7%, sensitivity of 75.0%, and specificity of 95.3%. Ten dMRI features showed a selection frequency of at least 70% across repeated model construction. Conclusions: MRI Type 1 is characterized by more severe and spatially extensive corpus callosum microstructural abnormalities than MRI Type 2, despite broadly similar vascular risk-factor profiles. The findings support the heterogeneity of sporadic age-related SVD and indicate that combined signal-based and biophysical dMRI metrics may improve MRI phenotyping. The observed associations should be interpreted as indirect markers of tissue microstructure and require confirmation in larger, independent, and longitudinal cohorts. Full article