Search Results (3,123)

Background: Surface roughness in turning operations is still verified predominantly after machining, which limits the possibility of timely corrective intervention. Methods: This study examined whether normal-direction peak-to-peak vibration displacement can serve as a practical low-frequency indicator of surface roughness during finish turning of EN AW-2011 aluminum alloy. The analysis was based on 190 synchronized displacement-roughness observation pairs obtained in one controlled experimental campaign on a CQ6230 conventional precision lathe, using a VB-8206SD displacement logger mounted radially on the tool holder and contact profilometry measurements reported as Ra and Rz. The analytical workflow included explicit quality-control safeguards for malformed rows, missing values, and obvious artefacts; in the present dataset, these checks did not indicate a failure state that would invalidate the main calculations. The workflow combined descriptive statistics, moving-average trend inspection, low-frequency FFT and STFT descriptors, Pearson correlation analysis, and ordinary least squares regression. Results: The displacement signal exhibited a mean value of 0.0446 mm with a standard deviation of 0.0256 mm and showed strong within-dataset linear relations with roughness parameters: Ra = 14.204 + 24.191 V (R² = 0.9929, RMSE = 0.052 µm) and Rz = 63.207 + 105.253 V (R² = 0.9905, RMSE = 0.264 µm). Conclusions: The results support setup-specific roughness-related process-state assessment using low-rate normal-direction displacement measurements. However, because the 190 records represent a time-ordered synchronized sequence rather than 190 independent cutting trials, and because no separate validation set was available, the fitted equations should be interpreted as descriptive within-setup calibration rather than as universally validated predictive models. Full article

Lignin is an abundant aromatic biopolymer, but its conversion into high-performance fibers remains challenging due to intrinsically poor spinnability, structural heterogeneity, and inefficient stress transfer in lignin-rich systems. In this study, a processing and structure strategy is demonstrated to overcome these limitations by transforming industrial black-liquor kraft lignin into a spinnable and load-bearing fiber component. Kraft lignin recovered from black-liquor waste was extracted and subsequently purified using a hot-water treatment to remove inorganic impurities and thermally unstable fractions, increasing lignin purity to 95.9% through extensive deionized water purification using a water-to-lignin ratio of 300:1. The purified lignin was then blended with poly(vinyl alcohol) (PVA), wet-spun into continuous filaments, and subjected to post-spinning hot drawing to induce molecular orientation. This sequential extraction, purification, blending, spinning, and drawing approach enables stable wet spinning and the continuous formation of lignin-rich lignin/PVA filaments without filament breakage, directly addressing the primary processing bottleneck of lignin-based fibers. Molecular-level miscibility between lignin and PVA is confirmed by the presence of a single glass transition temperature at 88.3 °C, indicating the formation of a homogeneous amorphous phase. SEM observations reveal composition-dependent surface roughness and non-circular cross-sectional morphologies arising from differential coagulation and shrinkage, demonstrating that lignin actively participates in the load-bearing fiber network rather than acting as a passive filler. As a result of purification-enabled spinnability, true blend miscibility, and post-spinning hot drawing, fibers with a lignin-to-PVA composition of 40:60 achieve a maximum tensile strength of 2.8 GPa, approaching the performance range of commercial high-strength polymer fibers. This work establishes a clear relationship between material structure, processing strategy, and resulting properties, highlighting the potential of industrial lignin waste as a sustainable precursor for advanced fiber applications. Full article

In this study, Delrin^® (POM) polymer was reinforced with 15 wt.% chopped ramie fiber (RF) to develop a sustainable composite, which was injection-molded and machined using abrasive waterjet machining (AWJM). SEM revealed a skin-core morphology with flow-induced RF alignment and small voids at bundle crossovers, indicating interfacial adhesion. A Taguchi L₉ (3³) design evaluated waterjet pressure (WJP: 100–300 MPa), traverse speed (TS: 100–200 mm/min), and stand-off distance (SoD: 1–3 mm) on kerf width (KW) and surface roughness (SR). Increasing WJP from 100 to 300 MPa lowered mean SR from 6.23 to 4.80 µm (23% reduction) and KW from 1.31 to 1.07 mm (reduction of 18%); enlarging SoD from 1 to 3 mm raised SR from 4.98 to 5.55 µm (an 11% increase) and KW from 1.12 to 1.20 mm (a of 7% increase); and raising TS from 100 to 200 mm/min narrowed KW from 1.24 to 1.11 mm (a 10.5% reduction) with a modest SR decrease from 5.45 to 5.28 µm. ANOVA confirmed WJP as the dominant factor for SR (79.8%), as well as a significant SoD (18.3%). For KW, the influence of WJP (68.8%) was substantial, followed by TS (19.9%) and SoD (11%). Linear models captured the trends well (SR: R² = 88.29%; KW: R² = 93.36%). A desirability-based multi-response optimizer yielded ideal conditions for TS (200 mm/min), WJP (300 MPa), and SoD (1 mm), predicting a KW of 0.94 mm and an SR of 4.1567 µm. Confirmation tests produced a KW (0.970 ± 0.01 mm) and SR (4.27 ± 0.05 µm), which are within 3.19% and 2.73% of the predicted values, validating the DoE regression approach. Full article

With the shortage of natural aggregates and the massive accumulation of iron tailings (ITs) solid waste restricting the sustainable development of asphalt pavement engineering, replacing natural aggregates with ITs has become a promising low-carbon solution with prominent economic and social benefits. However, the poor interfacial adhesion between ITs and asphalt severely restricts the engineering application of tailings, and the micro-interaction mechanism at their interface still lacks systematic clarification, which is the key research gap addressed in this work. Different from conventional macro road performance tests, this study innovatively combined molecular dynamics (MD) simulation with microscopic characterization, including Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM), to comprehensively reveal the interfacial interaction mechanism between ITs and asphalt at the molecular and microscales. The results indicate that asphalt molecules exhibit higher aggregation concentration and diffusivity on Al₂O₃ and Fe₂O₃ surfaces than on SiO₂ surfaces, proving stronger interfacial interaction between asphalt and iron-rich oxide minerals. Moderate temperature optimizes the adhesion performance of asphalt with Al₂O₃ and Fe₂O₃, while the interfacial bonding of asphalt on CaCO₃ and SiO₂ weakens as temperature rises. The silane coupling agent KH-550 can effectively react with acidic minerals, SiO₂ minerals in ITs, which significantly increases the concentration, diffusion coefficient, and distribution uniformity of asphalt molecules at the interface. FT-IR results verify that the combination of ITs and asphalt mainly relies on physical adsorption without generating new chemical bonds. AFM tests further confirm that alkaline minerals improve the surface roughness of asphalt mastic, and KH-550 greatly enhances the micro-adhesion force of the interface. The novelty of this work lies in clarifying the mechanism of typical mineral components in ITs and revealing the modification enhancement law of silane coupling agent and alkali minerals at the micro level. This study provides a scientific theoretical support for the high-value engineering utilization of ITs in asphalt pavement, and offers a reference for optimizing the interfacial modification design of solid waste aggregate. Full article

Bamboo surfaces are susceptible to scratches and contamination during service, which limits their durability and aesthetic performance. To address this issue, this study aims to develop a natural self-healing coating based on tung oil microcapsules. Tung oil microcapsules encapsulated within chitosan and gum arabic (TO/CS–GA MCs) were prepared by spray drying at two feed rates (100 and 200 mL h⁻¹) and incorporated into tung oil coatings applied on bamboo substrates. The effects of microcapsule content (1.0–11.0 wt%) and feed rate on the optical performance, mechanical performance, and self-healing performance of the coatings were systematically investigated. The results showed that increasing the microcapsule content gradually increased the color difference (ΔE) and surface roughness of the coatings, while the gloss decreased. The hardness, impact resistance, adhesion grade, and self-healing efficiency of the coatings exhibited a similar trend, initially increasing and then decreasing with increasing microcapsule content. This behavior indicates that an appropriate amount of microcapsules can enhance the coating performance, whereas excessive addition leads to particle agglomeration and structural defects. Under the better condition of 5.0 wt% microcapsule content and a spray-drying feed rate of 100 mL h⁻¹, the coating exhibited the best overall performance, including higher gloss retention, a hardness of 2H, an impact resistance of 3 kg·cm, relatively low surface roughness, and a self-healing efficiency of 28.16 ± 0.63%. These results suggest that the spray-drying feed rate plays an important role in regulating the particle size distribution and encapsulation efficiency of the microcapsules, which in turn affects their dispersion and rupture–release behavior within the coating matrix. Therefore, controlling the spray-drying parameters is crucial for optimizing the performance of microcapsule-based self-healing coatings. Overall, this study provides a sustainable strategy for developing natural polymer-based self-healing coatings and offers useful insights into the design of functional microcapsules for bamboo surface protection. Full article

This research aimed to evaluate the effects of formulation and process conditions on the physical and structural properties of starch–brewers’ spent grain films. Three factors were considered: BSG amounts (0, 1, 3, 5%), a possible ultrasonication pre-treatment, and different microwave gelatinization treatments (450 W for 80 and 90 s; 900 W for 45 and 50 s). An increase in BSG is responsible for increases in moisture (10.72 → 23.40%), water absorption (67.65 → 95.73%), density (0.90 → 1.27 g/cm³), browning index (5.86 → 85.88), UV blocking capacity (82.42% → 99.96% for UV_A; 61.28% → 99.86% for UV_B), and degradability in the first 7 days (58.72 → 66.57%), but dramatically decreases the Young’s modulus and tensile strength (fallen to 2.90 N/mm² and 0.21 N/mm², at 5% BSG). Sonication contributes to increased browning index (36.17 → 37.24), UV blocking capacity, solubility (49.35 → 51.49%) and Young’s modulus (4.40 → 4.77 N/mm²). The most severe microwave treatment (900 W, 50 s) minimizes moisture (15.83%) and water absorption (80.89%) and maximizes density (1.21 g/cm³), browning index (37.52), and Young’s modulus (5.37 N/mm²). SEM micrographs allow us to observe that the film surface appears rough, and the structure becomes increasingly porous as BSG % increases. The regression analysis indicates that the quadratic model effectively describes the relationships between the three factors and each of the most important properties of the films; it is suitable for predicting film behavior and optimizing their characteristics depending on the desired use. Full article

Ensuring the durability and safety of modern infrastructure critically depends on the quality and strength of concrete. The Ultrasonic Pulse Velocity (UPV) method is a widely used non-destructive testing technique for evaluating concrete properties; however, factors such as aggregate size distribution, compaction methods, and surface quality can significantly influence UPV results and their correlation with compressive strength. This study investigates the effects of different aggregate sizes and an innovative vibration-assisted compaction method—developed using piezoelectric (PZT) transducers—on the mechanical, ultrasonic, and surface properties of concrete. Four distinct aggregate size distributions were employed to produce sixteen concrete specimens with constant mix proportions. Unlike conventional low-frequency, high-power vibration practices, a high-frequency (40 kHz), low-power (120 W) vibration protocol was applied through PZT elements placed within the molds to enhance compaction and reduce entrapped air. Experimental results indicated that the heaviest specimen (7.13 kg) was the medium-aggregate sample compacted using tamping and rodding methods. The highest UPV value (4143 m/s) was obtained from the coarse-aggregate specimen subjected to three minutes of vibration. In contrast, the best compressive strength performance (22.73 MPa) was observed in the medium-aggregate specimen without any vibration treatment. The findings revealed that both aggregate size and advanced vibration techniques have significant effects on the mechanical properties, ultrasonic response, and surface quality of concrete. In addition, a proof-of-concept portable surface-finishing prototype consisting of a steel plate instrumented with multiple PZT transducers was developed, and preliminary trials qualitatively suggested improved surface leveling when applied in contact with the concrete surface. Surface roughness was quantified via image processing (Light Map 150 and Specular Map 150). The rough-area fraction decreased from ~29.8% in the untreated specimen to ~4.3% after ultrasonic application, indicating a marked improvement in surface leveling and overall surface quality. The results indicate that the applied PZT vibration protocol did not improve compressive strength; in several cases, particularly under prolonged excitation, a reduction in strength was observed. In contrast, a significant improvement in surface quality was achieved, with the rough-area fraction decreasing from approximately 29.8% to 4.3%. However, due to the limited number of specimens, the findings should be interpreted as preliminary. Overall, the method appears more promising as a surface enhancement technique rather than a direct alternative to conventional compaction methods. Full article

Urban heat dynamics are strongly influenced by the interaction between built structures, surface materials, and vegetation cover. This study investigates the relationship between land surface temperature (LST) and key urban morphological and structural parameters in a municipality of Thessaloniki, Greece. LST was retrieved from Landsat imagery using the NDVI-based emissivity method within Google Earth Engine (GEE). To characterize the urban form of the study area, a WorldView-2 summer image was classified to extract indices of surface roughness, built-up density, greenness density, building orientation and roof material type. Statistical analyses, including regression models and one-way ANOVA, were applied to assess the influence of these parameters on LST variability. Results reveal significant correlations between LST and both structural and vegetative factors, highlighting the cooling role of urban greenness and the amplifying effect of dense built-up areas and specific roof materials. The findings provide valuable insights into the spatial drivers of urban heat at a high-resolution scale, and offer practical guidance for planning strategies designed to lessen heat intensity in compact urban environments. Full article

In bridge widening projects under uninterrupted traffic conditions, vehicular vibration easily leads to damage in the interfacial transition zone (ITZ) and microstructural degradation of early-age concrete in wet joints. Taking a typical hollow slab-low T-beam widening structure as the object, this study introduces basalt micro fiber (BMF)-based ultra-high-performance concrete (UHPC) as the wet joint material and establishes a refined vehicle–bridge coupled dynamic model considering the time-varying stiffness of the joint material and road roughness excitation. The research indicates that although UHPC possesses excellent ultimate mechanical properties, its early-age setting process is extremely sensitive to vehicle-induced vibration. Numerical analysis reveals that while traditional temporary steel fixtures can effectively control the vertical relative displacement between the new and old girders within the critical value of 5.5 mm, the peak particle velocity (PPV) induced by heavy vehicles (buses and trucks) during the early pouring stage (<12 h) significantly exceeds the safety threshold of 3 mm/s, posing a severe threat to the directional distribution of steel fibers and interfacial bond strength. Therefore, this paper designs a single tuned mass damper (TMD) optimized based on Den Hartog’s fixed-point theory. Simulation results confirm that with the TMD configured, the vibration responses induced by buses across the entire speed range (≤120 km/h) are reduced below the safety limit; the vibration velocity induced by heavy trucks is also effectively controlled when combined with an 80 km/h speed limit. The collaborative strategy of “passive TMD vibration reduction + active traffic speed limit” proposed in this paper provides a theoretical basis for guaranteeing the early-age micro-forming quality of UHPC wet joints and overall traffic efficiency. Full article

Background: Phenotype prediction for eye, hair and skin color is used in a variety of forensic applications, such as trace analysis, the identification of unknown individuals, and analysis of historical DNA traces. The aim of this study was to evaluate the predictive accuracy of the HIrisPlex-S system in a homogeneous North German population. Methods: A cohort of 155 individuals from this population was sampled, and the 41 HIrisPlex-S SNPs were genotyped using the SNaPshot workflow. In addition, the participants assessed their own eye, hair, and skin color using a standardized questionnaire. The statistical analysis included the calculation of diagnostic indicators such as sensitivity (Sens), specificity (Spec), positive and negative predictive values, and accuracy (Acc). In addition, ROC analyses were performed. Results: The results indicated that predictions of skin and hair color were less accurate, whereas eye color could be determined more reliably. Brown and blue eye colors in particular were predicted accurately (brown: Sens = 94.7%, Spec = 87.7%, Acc = 89.5%; blue: Sens = 98.5%, Spec = 57.7%, Acc = 75.7%), while intermediate eye color (Sens = 0.0%, Spec = 100.0%, Acc = 69.1%), hair color and skin color were difficult to differentiate (e.g., blond hair color: Sens = 80.8%, Spec = 56.0%, Acc = 68.2% and pale skin color: Sens = 73.8%, Spec = 44.8%, Acc = 57.2%). Conclusions: In our study, the HIrisPlex-S system primarily provided rough directional information and could distinguish between very different phenotypes but reached its limits when it comes to similar characteristics. Full article

This study investigates the comminution behavior and beneficiation potential of lithium-bearing ores, zinnwaldite from Cínovec (Czech-Germany border) and lepidolite from Villasrubias (Spain) by integrating mineralogical analysis and mechanical characterization. The research is driven by Europe’s need for secure lithium supply chains. In particular, it focuses on the challenges associated with low-grade, fine-grained lithium micas found in hard-rock ores, which offer significant potential to supply in Europe but also pose substantial processing challenges. QMA (Quantitative Microstructural Analysis) revealed distinct differences in the textural and structural characteristics of the studied ores. Zinnwaldite-bearing rocks are coarser-grained with high interlocking and roughness, while lepidolite-bearing samples showed finer grains, lower roughness, and more disseminated mica distribution, indicated by their low clustering degree. In terms of mechanical characterization, zinnwaldite-rich ores have the lowest compressive strength, while lepidolite-rich samples showed the highest values, attributed to their finer grain size and more cohesive structure. This suggests that lepidolite may require higher energy input and finer crushing stages to achieve the target liberation size. These features influenced the breakage behavior observed during mechanical testing and comminution and are essential for enabling selective comminution, separating mica from gangue material. This study contributes to analyzing the potential of European hard-rock lithium resources from the perspective of upstream comminution, which is an essential step influencing downstream energy consumption, reagent use, and overall recovery efficiency. The results of this research emphasize that selective comminution should not rely solely on mineral hardness contrasts but must incorporate microstructural parameters such as clustering, grain size distribution, and orientation. Full article

Fracture roughness is critical to fluid flow behavior in fractured rock masses. However, the mechanism by which such roughness heterogeneity influences fluid flow and amplifies cubic law deviation remains incompletely understood. Current theoretical analyses are focused on uniform roughness or smooth parallel plates, neglecting the roughness heterogeneity in natural fractures. The equivalent fracture geometry models with heterogeneous roughness are established based on the fracture walls of the smooth parallel plates and the sinusoidal profiles in this study. Based on the geometry models and derived from the Navier–Stokes equations, two simplified fracture models are proposed: the equivalent plate–sinusoidal walled and the sinusoidal–sinusoidal walled fracture model, validated via COMSOL Multiphysics. A roughness heterogeneity index Z_r is defined to quantify the roughness heterogeneity. The influence of roughness heterogeneity on hydraulic behavior (e.g., fluid flow rate, equivalent hydraulic aperture) is analyzed and compared with those of uniform roughness and smooth parallel plates. Additionally, the influence of roughness heterogeneity on the power–law exponent relationship between fracture mechanical aperture and flow rate is examined. The results indicate that the flow rate and hydraulic aperture decrease with increasing roughness heterogeneity, while the deviation of fluid flow from the cubic law increases. The power–law exponent can be as high as 15.5. This study provides theoretical models for understanding the effects of roughness heterogeneity and a reference for extending flow models to complex fracture morphologies. Full article

Efficient heat dissipation is crucial for semiconductor devices; however, conventional thermal management materials often cannot meet practical demands because of inadequate thermal conductivity and mismatched coefficients of thermal expansion with semiconductor materials. In this study, we develop a synergistic process integrating magnetron sputtering and annealing to fabricate a composition-controllable Cr/Cr₃C₂ composite interlayer on diamond surfaces. By regulating the annealing temperature from 700 to 1100 °C, three key parameters of the Cr/Cr₃C₂ composite interlayer can be tailored: the thickness varies from ~200 to 800 nm, the Cr/Cr₃C₂ fraction is adjustable, and the surface roughness ranges from 33.3 to 61.6 nm. In the current research, the sample that was annealed at 900 °C for 2 h exhibited the highest coating uniformity, with carbide coverage exceeding 98% and no discernible porosity. This optimized annealing process produces an interlayer with robust coverage, moderate thickness (~300 nm), and low surface roughness (Ra = 33.3 nm), thereby markedly enhancing interfacial bonding and thermal-transport performance. The resulting composite achieves a maximum thermal conductivity of 605.27 W·m⁻¹·K⁻¹, corresponding to 211% of the experimentally measured value for the uncoated sample. Analyses combining the diffusion mismatch model and experimentation indicate that the enhancement originates from improved phonon spectral matching and increased interfacial adhesion energy. This work provides processing guidance for precise interface engineering in high-thermal-conductivity diamond/copper composites. Full article

The complex surface architecture of natural oyster reefs is widely considered to promote biological attachment, yet the underlying mechanisms and the relevance to the design of artificial reefs are not fully understood. Here, we combined field experiments, 3D surface characterization, and numerical modelling to quantify how reef-like roughness regulates biofouling development and near-wall flow around artificial substrates. Surface morphological characteristics of natural oyster reefs were first obtained by 3D scanning and used to fabricate concrete panels with simulated rough textures, while traditional smooth concrete panels served as controls. The two types of panels were simultaneously deployed in the target sea area for a hanging-panel experiment. Samples were collected after 3, 6, 9, and 12 months to track changes in biofouling communities. At each sampling time, the panel surfaces were quantified by canopy roughness ($R_C$), surface heterogeneity ($\sigma$), and fractal dimension ($D$), and these metrics were integrated into numerical simulations combined to resolve the flow field, turbulence kinetic, and near-wall shear stress around the colonized panels. The research results show that, after 12-month immersion, the mean thickness of the biofouling layer on rough and control panels reached 6.39 mm and 5.91 mm, respectively. Rough panels exhibited consistently higher $R_C$ and $\mathsf{\sigma }$ than controls, and these two parameters are strongly linearly correlated ($R^2=0.891)$. Numerical simulations reveal that increased $R_C$ enlarges the oyster settlement shear-stress window (OSSW), indicating more favorable hydrodynamic conditions for oyster settlement and growth on rough panels. Nevertheless, the hydrodynamic differences between the initial rough panels and control panels gradually diminish over time, suggesting that biological growth can progressively naturalize initially smooth substrates. These findings advance the mechanistic understanding of how small-scale roughness and biofouling co-evolve to shape oyster habitat quality and provide a quantitative basis for the eco-engineering design of artificial oyster reefs. Full article

A rock-socketed pile model load test was conducted for the renovation project of the dangerous old bridge at Shaoping Bridge. The experiment focused on the core parameter of the roughness factor (RF) of the pile body, revealing its influence on the bearing characteristics. The study delved into the load–displacement relationship, ultimate bearing capacity evolution, axial force transmission mechanism, average lateral resistance performance characteristics, and pile–soil relative displacement law of test piles in complex rock formations under different RF values. The research results indicated the following: The test pile exhibited typical brittle failure. At the moment of failure, the load at the pile head dropped abruptly, resulting in a steep drop in its load–displacement curve. Under ultimate load conditions, the average attenuation amplitudes of axial force in the four test piles decreased progressively in Rock Layer I, II, and III, measuring 26.96%, 14.86%, and 10.84%, respectively. The average side resistance distribution along the pile shaft showed a single-peak pattern, peaking in Rock Layer I. Increasing RF effectively enhanced the bearing capacity of test piles. However, a higher RF value does not necessarily yield better results, as it exhibits an inverted U-shaped relationship with bearing capacity. Under the specific conditions of this study, the highest bearing capacity among the tested RF values was observed at RF = 0.168; beyond this threshold, performance actually declined. The pile-top load was primarily shared by side resistance and end bearing resistance. Both components initially increased and then decreased with increasing RF, where the end bearing resistance accounted for 43.64~49.47% of the upper load. Full article