Search Results (6,926)

Expansive mudstone tunnels often suffer long-term convergence and support damage because excavation-induced unloading is coupled with water-induced swelling. This study proposes a particle flow modeling framework for expansive mudstone tunnels by linking tunnel-wall displacement, swelling pressure, and the equivalent particle radius expansion coefficient. Constant-volume swelling pressure tests were first conducted to determine the representative swelling pressure of the mudstone. An independent confined particle model was then established to calibrate the relationship between macroscopic swelling pressure and microscopic particle expansion. The results show that a stable swelling pressure of 300 kPa corresponds to an equivalent particle radius expansion coefficient of 3.11%. Incorporating this calibrated swelling mechanism into the tunnel model indicates that swelling intensifies excavation-induced damage, increasing the final crack number from 1566 to 1852 and enlarging the equivalent damage-zone diameter from 21.6 m to 22.8 m. Under the original support scheme, the damage depth reaches 5.45 m, and the final crown settlement reaches 177.6 mm. After reinforcement, these values decrease to 3.40 m and 81.1 mm, respectively. Field monitoring confirms the predicted deformation-control trend. The proposed framework provides a practical approach for simulating swelling-induced damage evolution and optimizing support design in expansive mudstone tunnels. Full article

Water-retaining roller-compacted concrete (RCC) dams suffer severe deterioration under coupled moisture ingress and freeze–thaw (F-T) cycles. To elucidate the damage mechanisms, this study employed industrial X-ray computed tomography (CT) synchronized with uniaxial compression and acoustic emission (AE) monitoring. The cross-scale damage evolution of RCC was investigated under dry, water-saturated, 25, and 50 F-T cycle conditions. The results indicate the following: (1) Macroscopically, F-T damage causes linear peak stress attenuation, shifting the failure mode from brittle axial splitting to ductile oblique shear. (2) Mesoscopically, frost-heaving stress expands native mesopores (500–2500 μm), increasing their volume fraction from 8.45% to 14.86% and remodeling isolated voids into a 3D interconnected defect network. (3) Microscopically, GMM-based AE clustering reveals a fracture transition. Driven by moisture lubrication and defect propagation, global shear cracks surpass the 50% threshold at 25 cycles (53.5%), reaching 68.6% at 50 cycles. (4) For cross-scale mapping, calibrating the AE b-value via Aki’s method decouples pore-water signal attenuation. Its pre-peak characteristic (an initial decrease followed by a rebound) accurately maps microcracks unstably coalescing along interconnected pores to form macroscopic shear planes. This cross-scale mechanism provides a scientific paradigm for condition monitoring of massive concrete in cold regions. Full article

Multiphase swirling flows in confined spaces induce highly destructive, nonlinear fluid–structure interaction (FSI) vibrations. Understanding the underlying physical mechanisms is critical for ensuring the safety of industrial operations. This study proposes a mesoscopic multiscale framework coupling the Multi-Relaxation Time Lattice Boltzmann Method with Large Eddy Simulation (MRT-LBM-LES) and the Flügge thin-walled cylindrical shell equations to analyze two-way FSI responses. Variational Mode Decomposition (VMD) and the Hilbert–Huang Transform (HHT) are employed to decouple non-stationary broadband excitation signals. The macroscopic topological evolution of the swirling air core—from initial depression to critical breakthrough—is accurately captured. Dynamic mapping reveals a strict time-domain phase-locking mechanism between macroscopic flow instability and microscopic high-frequency structural excitation caused by cavitation bubble collapse. Furthermore, a dimensionless cross-scale energy cascade index is defined to quantify energy transfer. Results indicate that while higher discharge flow rates delay the critical breakthrough, they trigger a delayed, high-amplitude step mutation in the energy cascade, amplifying the global cumulative excitation energy by nearly 75%. Notably, the dominant high-frequency excitation consistently converges within a narrow band of 760 Hz to 790 Hz, independent of flow rate variations. These findings provide a theoretical foundation for unsteady excitation source localization and targeted vibration reduction in complex industrial pipeline networks. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

The Dafosi well field is a typical Huang-Long Jurassic low-rank coalbed methane (CBM) field. Clarifying its CBM geochemical characteristics and the mechanisms of its formation is of significant importance for deepening the understanding of the formation mechanisms of low-rank CBM in China and for the scientific assessment of its resource potential. A total of eight gas emission samples from six coalbed methane wells in the Dafosi coalfield were collected, along with 22 coal samples from the 4^# coal seam. Detailed analyses of microscopic coal petrographic components, gas chemical compositions, and carbon isotopes were performed. By integrating data from the 20 relevant literature sources on coalbed gas composition and isotopic characteristics within the study area, a comprehensive dataset comprising 28 sets was utilized to examine the carbon isotope characteristics and genesis types of both CH₄ and CO₂ in the coalbeds, as well as elucidate the mechanism behind CH₄ carbon isotope depletion. The findings indicate that in the primary 4^# coal seam’s microscopic petrographic composition, the organic matter content is considerably higher, averaging 93.2%. Among these, the inertinite group is dominant, averaging 68.2%; the vitrinite group is the next most abundant, averaging 22.8%. The CBM composition is predominantly CH₄, with concentrations varying from 68.753% to 98.006%, averaging 80.276%. N₂ concentrations range from 1.259% to 29.926%, averaging 17.476%. CO₂ concentrations vary from 0.04% to 2.380%, averaging 1.032%. The average concentration of heavier hydrocarbons C₂ and above is less than 0.078%, indicative of typical dry gas characteristics, C₁/C_1~n > 0.999. The concentration of CH₄ and N₂ was negatively correlated. δ¹³C₁ ranges from −87.200‰ to −62.400‰, averaging −75.802‰. CH₄ is composed of secondary biogenic gas with dominant content and a small amount of thermogenic gas. δ¹³C_CO2 ranges from −41.693‰ to −7.065‰, averaging −20.016‰. CO₂ is an organic gas, mainly derived from thermal degradation and microbial degradation of organic matter. The mechanism responsible for the light carbon isotopic composition of δ¹³C₁ lies in the fact that most of CH₄ is produced by CO₂ reduction, and a small amount is produced by acetic acid fermentation. In the gas generation process of these two pathways, biogenic methane will eventually enrich light carbon isotopes, resulting in light δ¹³C₁. Full article

Traditional cement-based foamed lightweight soils suffer from high construction costs, poor durability, and low solid waste utilization efficiency, which severely restrict their engineering application. A novel polyvinyl alcohol (PVA)-reinforced solid waste-based foamed lightweight soil is fabricated using Bayer red mud, mineral powder, and fly ash. To clarify the durability evolution mechanisms, systematic freeze–thaw cycling, long-term water immersion, and sodium sulfate erosion tests were conducted on PVA-reinforced solid waste-based, unreinforced solid waste-based, and pure cement-based specimens. The results demonstrate that the PVA-reinforced specimen achieves optimal freeze–thaw resistance with only 17.10% strength loss after 50 cycles, owing to the internal three-dimensional fiber network that restrains crack propagation and enhances matrix toughness. It also exhibits excellent long-term water immersion stability, with a mild strength increment of 4.04–10.33% after 120 days. In contrast, the CN exhibited a strength increase of 43.62%, attributed to its lower initial strength caused by incomplete hydration; however, its final strength remained between those of the other two groups. In sulfate environments, unreinforced solid waste-based specimens present superior corrosion resistance, while PVA fiber-induced interconnected pores slightly weaken sulfate erosion resistance. Microscopic analysis confirms that the generation of alunite and gypsum hydration products fundamentally causes performance discrepancies among different specimens. Different from previous studies focusing on single fiber modification or single solid waste partial replacement of cement, this study innovatively adopts a composite modification strategy of “multi-solid waste alkali-activated matrix + PVA fiber toughening”, and systematically reveals the durability evolution mechanism under multiple harsh environments. Full article

Two-dimensional (2D) layered materials—graphene, hexagonal boron nitride (hBN), transition metal dichalcogenides (TMDs), and layered van der Waals (vdW) thiophosphates—constitute a rapidly expanding family whose properties are governed by weak van der Waals interlayer coupling and strong intralayer bonding. This review surveys the principal classes of 2D layered materials and systematically pairs each class with the low-frequency noise (LFN) spectroscopy studies performed on it mainly between 2013 and 2026. Unlike earlier material-specific reviews, it systematically compares the experimental device configurations, assigned microscopic mechanisms, and research gaps. The review also identifies specific research priorities. Full article

Poly (vinyl chloride) (PVC) is widely used in many products due to its increased flexibility and processability. It is preferred in many industrial applications, especially in the plasticized PVC cable industry due to its excellent insulation properties. PVC is quite hard and can be difficult to process. Therefore, it requires additives such as plasticizers. Plasticizers typically reduce the glass transition temperature (Tg) and provide flexibility by reducing the workable temperature level. In the PVC compound production industry, phthalate-based plasticizers are preferred due to their low cost. Commonly used plasticizers are adipates, azelates, trimethylates, phthalates, benzoates, and chlorinated paraffins. The aim of the study was to investigate the plasticizer changes in PVC compounds used in cable insulation applications by synergistic effects of adipate, trimellitate, and phthalate-based plasticizers such as dioctyl terephthalate (DOTP), 2-ethyl hexyl adipate (DOA), and tris(2-ethylhexyl) benzene-1,2,4-tricarboxylate (TOTM). In this study, the effects of plasticizer additives were investigated on the structural, morphological, thermal, and mechanical properties of PVC compounds in the cable industry. Fabricated test products were characterized using characterization methods such as Fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscope–energy-dispersive X-ray (SEM-EDX) spectroscopy, thermal gravimetric analysis (TGA), tensile test, and density test. Successfully fabricated samples were tested before and after aging. The highest elongation at break of PVC flat sheet (244.96%) was obtained with the use of DOA plasticizer. The highest tensile strength was measured as 17.85 MPa for the sample containing 50 phr DOTP. Furthermore, no significant mass loss was observed up to 238 °C, while substantial decomposition occurred in the samples containing 50 phr DOTP, 50 phr DOA, and 50 phr TOTM between 238–338 °C, followed by gradual degradation at 483 °C and 683 °C. As a result, it has been determined that the use of DOA plasticizer in PVC compounds used in the cable industry is more effective than DOTP and TOTM plasticizers. Full article

This study developed a composite rejuvenator comprising recycled polyethylene wax (PREW), waste cooking oil (WCO), and epoxidized soybean oil (ESO) activated by the tertiary amine catalyst BDMA to improve the intermediate-temperature rejuvenation of aged SBS-modified asphalt binder. The binder was subjected to combined rolling thin-film oven and pressure aging vessel aging. Conventional tests, rotational viscosity, bending beam rheometer, multiple stress creep recovery, fluorescence microscopy, and Fourier transform infrared spectroscopy were used to evaluate macroscopic, rheological, and microstructural properties. Aging hardened and embrittled the binder, increased softening point and viscosity, reduced penetration and ductility, and disrupted the polymer-rich phase. PREW reduced flow resistance and retained relatively high-temperature structural stability, whereas WCO improved flexibility and flowability, although excessive softening impaired high-temperature stability. ESO/BDMA treatment was accompanied by changes in oxygen-containing functional group-related absorption regions and improved apparent connectivity of the SBS-rich phase. Among the tested temperatures, 120 °C provided the best overall balance among the evaluated properties, satisfying low-temperature stress-relaxation requirements while limiting high-temperature creep deformation. These results identify 120 °C as the preferred treatment temperature for the PREW/WCO/ESO-BDMA rejuvenation system. Full article

In social and economic systems, collective returns often depend nonlinearly on group size, exhibiting a curvature that can be convex or concave, yet how this curvature reshapes cooperation transitions in higher-order social dilemmas is not fully understood. In this work, we study a controlled public goods game on hypergraphs with minimal ad hoc parameters, where linear pairwise interactions are supplemented by a three-body power-law payoff whose exponent $\gamma$ controls the curvature of the collective return. Through systematic numerical simulations and microscopic diagnostics, we show that this curvature qualitatively reshapes cooperation transitions: for $\gamma <1$, the transition is continuous-like, similar to the linear benchmark $\gamma =1$, whereas for $\gamma >1$, the transition becomes abrupt and first-order-like. This distinction remains robust across different system sizes and multiple hypergraph topologies. We further show that cooperation in the $\gamma >1$ regime is primarily driven by a cascade-like proliferation of fully cooperative triads, accompanied by the depletion of partially cooperative configurations. Based on this mechanism, we predict and verify that a strict three-body product-form payoff—although motivated by a completely different social mechanism—produces the same discontinuous cooperation transition. Full article

Ultraviolet (UV) radiation in high-altitude regions critically accelerates asphalt aging by inducing surface oxidation, molecular chain scission, and loss of low-temperature crack resistance. However, systematic comparisons of the macro-rheological and micro-chemical evolution between base asphalt and SBS-modified asphalt under UV aging remain insufficient. In this study, two types of asphalt (virgin and SBS-modified) were subjected to three aging protocols, namely short-term thermal oxidation (RTFOT), long-term thermal oxidation (PAV), and equivalent UV radiation for 13 h, 26 h, and 37 h. Low-temperature rheological properties were evaluated using the bending beam rheometer (BBR), while atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) characterized the microstructural and chemical changes. The results show that long-term thermal oxidation causes the most severe deterioration of low-temperature rheological performance, whereas short-term thermal oxidation and 13 h UV aging exhibit comparable effects. For SBS-modified asphalt, extending UV exposure from 13 h to 37 h leads to progressive stiffening and loss of relaxation capacity at −12 °C and −18 °C. However, the m-value shows a non-monotonic response at −24 °C, indicating that the temperature dependence of UV aging is more complex at extremely low temperature. For base asphalt, aging promotes the formation and subsequent agglomeration of bee-like structures. For SBS-modified asphalt, the sulfoxide index increases monotonically, while the carbonyl index first increases and then decreases. Although 13 h UV aging and RTFOT produce similar macroscopic outcomes, their mechanisms differ fundamentally, where UV aging is hypothesized to act primarily via photon-induced bond scission, whereas thermal oxidation proceeds through radical chain reactions. Full article

This study investigates the strength development, crack evolution and toughening mechanism of basalt fiber-reinforced desert sand high-strength concrete. An L9(3³) orthogonal design was first used to optimize the reference mixture, after which basalt fibers with volume fractions of 0, 0.3%, 0.4% and 0.5% were incorporated. Mechanical testing, digital image correlation, SEM, XRD, TG and FTIR were combined to clarify the relationship among fiber dosage, crack propagation and microstructural reinforcement mechanisms. The optimized matrix mixture was obtained with a water-to-binder ratio of 0.32, a desert sand replacement ratio of 40% and a fly ash content of 20%. The incorporation of basalt fiber had little influence on the 28 d compressive strength, whereas the splitting tensile strength was markedly improved. The highest splitting tensile strength was observed in the 0.4% fiber group, reaching 5.46 MPa, which was 12.81% higher than that of the reference mixture. DIC results showed that basalt fiber reduced strain localization and limited crack opening. The 0.5% group had the lowest COD, while the 0.4% group showed a better balance among tensile strength, strain redistribution and crack-opening control. SEM observations showed fiber bridging and fiber–matrix interaction near the fracture region. Meanwhile, XRD, TG-DTG and FTIR showed no obvious changes in the main phases or functional groups, indicating that the improvement was mainly related to the physical crack-control effect of basalt fibers rather than chemical modification of the matrix. Overall, 0.4% basalt fiber was identified as the preferred dosage for the present system. Full article

Photocatalysis is a promising route for the environmentally friendly destruction of organic pollutants and recycling the polluted water in industrial contexts for future environmental challenges. In this novel research work, the coupling of definite proportions of silver phosphate and g-C₃N₄ is carried out sonochemically for engineering S-scheme Ag₃PO₄/g-C₃N₄ heterojunctions. With the data obtained from a N₂-adsorption–desorption isotherm, a diffuse reflectance spectrum, X-ray diffraction, a high-resolution transmission electron microscope and zeta potential measurement, as-synthesized nanocomposites are fully characterized and defined. Successful coupling of Ag₃PO₄/g-C₃N₄ heterojunctions was verified given the existence of diffraction peaks of g-C₃N₄ and Ag₃PO₄; the shift in the peak position of the DRS spectrum of g-C₃N₄ from 440 to 463 nm; and the decrease of 68% in the photoluminescence emission peak. The crystalline size of the nanocomposite decreased from 76 to 25 nm, which was ascribed to coupling of Ag₃PO₄ on g-C₃N₄ under sonochemical conditions. The as-synthesized nanocomposites exhibited different trends in the destruction of rhodamine B dye. The experimental results indicated that the sample containing 15 weight % of Ag₃PO₄ degraded 89% of the RhB dye. Precise analysis of reactive radicals species experiments indicated that superoxide radicals and positive roles directed the charge transportation between g-C₃N₄ and Ag₃PO₄ semiconductors toward the S-scheme mechanism that produces charge radicals of auspicious redox efficiency. Full article

Ilmenite is the core carrier of titanium resources in China. Conventional flotation systems generally have the problems of insufficient collector adsorption efficiency and limited separation index. Microwave pretreatment can strengthen the flotation process by activating the surface of minerals, but its regulation mechanism on the interface properties of ilmenite and the adsorption behavior of collectors remains to be systematically elucidated. Based on the previous research on the flotation separation effect of the ‘OHA + HDPA composite collector + microwave pretreatment (power of 800 W and irradiation time of 180s)’ system, this paper uses the OHA + HDPA (mass ratio 3:1) composite system as the collector and uses surface tension, contact angle, Zeta potential, infrared spectroscopy and X-ray photoelectron spectroscopy, and other multi-scale complementary characterization methods to systematically study the effect of microwave activation on the wettability of ilmenite surface and the adsorption of collector interface. The results show that the wettability of ilmenite surface by microwaves presents a two-way regulation characteristic. In a pure water system, microwave activation increases the surface polar active sites, the water contact angle decreases from 48.44° to 46.65°, and the hydrophilicity is slightly enhanced. Under the action of the collector, microwaves promoted the directional adsorption and orderly arrangement of reagents, the contact angle of minerals increased to 85.24°, the adhesion work reached 0.560 J/m², and the surface hydrophobicity and solid–gas adhesion ability were significantly improved. Interfacial electrokinetic analysis showed that microwave activation enhanced the positive surface charge of ilmenite, and the isoelectric point shifted from pH 5.1 to alkaline to pH 6.3. In the range of pH 2–10, the Zeta potential of the sample after microwave treatment shifted more negatively, which was due to the synergistic enhancement of electrostatic attraction and chemical chelation sites. Microscopic characterization confirmed that the collector was attached to the surface of ilmenite in the form of chemical adsorption. Microwaves did not change the essential properties of adsorption but increased the adsorption capacity of the collector by 10.9%, and the adsorption layer was more compact and orderly. A mechanism analysis reveals that microwave irradiation induces the oxidation of surface Fe²⁺ to Fe³⁺, and its atomic proportion increases from 23.91% to 38.64%, which significantly enhances the chelation between the collector and the iron site and the stability of the chemical bond. At the same time, combined with the change of XPS coordination environment, it is speculated that microwaves can induce lattice distortion, change the coordination environment of titanium atoms, increase the proportion of Ti-O-Fe bridge oxygen structure, increase the unsaturated titanium active site, and strengthen the coordination between the collector and the titanium site. The synergistic activation of iron–titanium multi-sites together enhances the adsorption strength and adsorption capacity of the collector. This study can provide theoretical support at the interface chemical level for the development of high-efficiency ilmenite flotation process. Full article

The Shaximiao Formation in the Sichuan Basin hosts abundant tight oil resources; however, its reservoirs are typified by low porosity, low permeability, pronounced pore–throat structural heterogeneity, and highly complex microscopic crude oil seepage behavior. This study systematically investigates the microscopic flow mechanisms of crude oil in the Shaximiao Formation using a microfluidic experimental platform coupled with an integrated physical simulation system that enables real-time monitoring of dynamic imbibition throughout the fracturing–shut-in–flowback cycle. Experiments were conducted across three reservoir quality classes (Class I, II, and III), seven discrete shut-in durations (4, 8, 12, 24, 36, 42, and 54 h), and two representative fracturing fluid injection rates (12 and 20 m³/min). The results show that (1) residual-oil exhibits a distinct spatial distribution pattern: enrichment in large pores and large throats, with minimal retention in small pores and small throats; (2) moderate extension of shut-in duration significantly enhances movable oil saturation, whereas excessive shut-in time drives partial movable oil to transform into film flow or become trapped in dead-end pores, thereby exacerbating residual-oil retention; (3) the proportion of movable oil decreases gradiently with declining reservoir quality, following the order: Class I > Class II > Class III reservoirs; and (4) for the same reservoir type, a lower injection rate (12 m³/min) improves sweep efficiency in small pore–small throat regions and reduces residual oil retention, while a higher rate (20 m³/min) tends to induce an unbalanced seepage phenomenon, “preferential breakthrough in large pores and persistent retention in small pores”, which impairs the overall reservoir stimulation effect. Full article