Search Results (1,253)

The article investigates damage in textile-reinforced rubber conveyor belts caused by impact loading. The study aims to evaluate how impact conditions and belt structural properties affect severe damage formation and to develop predictive models for identifying critical operating conditions. Damage assessment was performed using visual inspection and computed tomography (CT), with CT serving as a reference method due to its ability to detect internal defects in the load-bearing carcass. CT identified more severe damage cases than visual inspection, confirming its higher sensitivity. Experimental tests were carried out with impact heights between 0.8 and 2.6 m and impact weights from 50 to 100 kg. The results showed that impact energy is the dominant factor influencing damage formation, as higher impact heights and weights significantly increased the probability of severe damage. Belt structural characteristics also affected damage resistance, especially the thickness of the top cover, which reduced the risk of failure. To predict severe damage, Logistic Regression, Random Forest, and XGBoost models were applied, all achieving excellent performance (AUC > 0.95). Logistic Regression (AUC = 0.994) additionally enabled the estimation of damage probability and the identification of critical impact conditions. The proposed approach supports safer operating limits, risk assessment, and predictive maintenance in conveyor systems. Full article

In response to the current limitation where conventional constant volume combustion apparatuses are generally confined to pressure ratings of 5–20 MPa, insufficient for the demands of ultra-high-pressure combustion fundamental research, this study designs and verifies a high-pressure-resistant constant volume combustion apparatus with a rated working pressure of 250 MPa. The strength design and safety factor calculation for the combustion chamber main body were conducted based on the Lame thick-walled cylinder elastic theory. A finite element numerical simulation method was systematically employed to perform static analysis, transient impact response analysis, and high-cycle fatigue-life assessment of the key components of the apparatus. The results indicate that under a 250 MPa design internal pressure load, the maximum circumferential stress at the inner wall of the combustion chamber main body is 328.0 MPa, with a safety factor greater than 1.5, complying with relevant safety codes for high-pressure vessels. Under transient loading simulating combustion impact, the maximum equivalent stress of all structural components is below the material yield strength, with a maximum elastic deformation of less than 0.06 mm, demonstrating excellent structural stiffness and impact resistance. Fatigue assessment with a design-life target of 1.0 × 10⁶ pressure cycles shows that the cumulative damage values for all components are significantly less than 1.0, meeting the reliability requirements for long-term cyclic service. This apparatus integrates functional modules such as high-pressure precision gas mixing, high-energy reliable ignition, high-speed transient parameter acquisition, and safe product collection, providing a stable, controllable, and safe experimental platform for in-depth research on the combustion mechanisms of gaseous fuels under ultra-high-pressure conditions. Full article

Localized failures of structural components can lead to serious social, economic, and environmental consequences, such as the collapse of an entire structure or part of it. Therefore, it is important to thoroughly investigate and justify the acceptance criteria for these components, taking into account their performance in extreme conditions. However, the scientific literature lacks a systematic analysis of how various factors can affect the resistance of structures and influence acceptance criteria under extreme conditions. Therefore, this study investigates the typical substructures of reinforced concrete frame buildings in areas that are potentially prone to local collapse. To assess their resistance and structural robustness, an analytical model has been developed. The results of 22 tests on typical substructures of monolithic and precast frames, reported in various research studies, were used to validate this model. Further, this analytical model was used to conduct a parametric study on the impact of various factors on the performance of substructures under extreme conditions. These factors included the depth-to-span ratio of the beam, the strength of the bond between the steel reinforcement and the concrete, the stiffness of the horizontal bracing within the substructure, and the proportion of the effective depth to the total depth of the beam section. It has been found that the ultimate rotation angle in the plastic hinge of beams increases as the ratio of the beam’s cross-sectional depth to the span increases. An increase in the bond strength between the reinforcement and concrete leads to a decrease in the ultimate rotation angles in the plastic hinge at the flexural and arch stages of resistance and, in some cases, to reinforcement rupture without transitioning to the catenary stage of resistance. A decrease in the ratio of the effective depth of the beam section to its overall depth leads to an increase in the load-bearing capacity at the catenary stage of 19%. Full article

High sound pressure level (SPL) acoustic sensing requires miniaturized microphones that can operate under large acoustic loading while maintaining mechanical linearity, sufficient sensing response, and broadband audio frequency behavior. This work targets high-SPL operation and numerically investigates a graphene piezoresistive MEMS microphone based on a membrane-supported beam–island diaphragm. The proposed structure retains a continuous membrane for acoustic load bearing, while the upper beam–island topology redirects deformation-induced strain toward beam root regions where graphene piezoresistors are placed. This design is intended to increase the local strain available for piezoresistive readout without simply relying on larger global diaphragm deflection. Finite-element analysis was used to optimize the diaphragm geometry and evaluate strain enhancement, pressure response linearity, modal behavior, and harmonic response. Under the 170 dB SPL reference condition, the optimized structure increases the peak structural strain from 47.83 με in a thickness-equivalent solid diaphragm to 562.53 με, achieving an approximately 11.8-fold enhancement in local sensing strain while maintaining a highly linear pressure response (R2 > 0.9999). Additionally, the results also show that the sensor exhibits a high first natural frequency of 64.07 kHz and a small response variation of approximately 0.94 dB within the 0–20 kHz target frequency range, indicating excellent dynamic stability and high-fidelity signal transduction characteristics. To connect the structural response with piezoresistive readout, first-order electromechanical output estimation was further performed using representative graphene gauge factors, quarter-bridge readout assumptions, contact resistance correction, and Johnson-noise-limited signal-to-noise ratio estimation. A ±5% geometric tolerance check further indicates that the membrane side length is the most fabrication-sensitive parameter, while the selected design remains generally robust except for reduced linearity margin under positive membrane side-length deviation. These results demonstrate the potential of the proposed graphene-based MEMS microphone for high-SPL broadband acoustic sensing applications in harsh and high-intensity acoustic environments. Full article

Conductive silicone interfaces are promising polymeric materials for wearable bioelectronic systems because they combine electrical continuity with elastomeric compliance, environmental durability, and moldability. In low-voltage wearable microcurrent interfaces, however, functional performance is governed not only by intrinsic material conductivity, but also by conductive network continuity, molded geometry, interfacial contact, and transient electrical response. In this study, we developed a spike-structured conductive silicone interface using a commercially available electrically conductive two-component silicone rubber and investigated its structure–electrical property relationships as a volume-resistive polymer interface. The interface consisted of a conductive silicone body with protrusions 7 mm in height and 3.6 mm in diameter, supported by a 1 mm base layer and electrically integrated through an Ag-paste-connected upper conduction region. Using a representative electrode-level resistance of 47.08 Ω, the geometry-derived apparent interfacial resistive response was estimated as 18.0 Ω·cm for the three-spike configuration and 24.0 Ω·cm for the four-spike configuration. The corresponding effective conductive areas were 0.305 cm² and 0.407 cm², respectively, giving analytical current-density amplification factors of 9.82 and 7.37 relative to a planar 3 cm² reference interface. Positional resistance mapping yielded an overall mean resistance of 47.80 ± 4.57 Ω, indicating acceptable electrical reproducibility across the structured conductive silicone interface. In addition, oscilloscope-based transient response analysis under a 5 V, 1 kHz square-wave input showed that the conductive silicone interface maintained the overall pulse waveform while showing a modest reduction in overshoot from 3.4 ± 0.1% to 2.7 ± 0.1%, with FFT traces used as qualitative waveform-monitoring displays. Formulation-dependent comparison further showed that increasing the silicone-rich fraction increased the measured resistance from 105 Ω to 145 Ω, whereas increasing conductive carbon loading reduced resistance but aggravated surface transfer. These results show that the conductive silicone interface functions not simply as a soft conductor, but as a volume-resistive, geometry-defined current-transfer medium whose behavior is governed by the coupled effects of conductive network formation, spike architecture, electrode-level resistance, and transient pulse response. This study provides a practical materials/interface design framework for spike-structured conductive silicone electrodes in wearable bioelectronic and electroceutical devices. Full article

Adhesive joints typically require high safety factors, as their mechanical performance is highly sensitive to environmental and manufacturing variations. Health monitoring can reduce these safety factors by continuously assessing the condition of the joint. While intrinsic and extrinsic sensing approaches exist, they are often based on periodic inspection or manual sensor integration, which limits their suitability for continuous in-service monitoring. This study investigates a novel sensor placement using additively manufactured strain sensors deposited by jet dispensing across the adhesive gap. Tensile lap-shear specimens were fabricated using CFRP (carbon-fiber-reinforced plastic) laminate, an epoxy adhesive, and silver-ink strain sensors placed internally within the joint and externally across the adhesive gap. Mechanical testing revealed that externally printed sensors produced an average resistance change of 65.3% near the failure stress of the adhesive joint, an order of magnitude higher than sensors embedded within the adhesive layer with 6.6% average resistance change. However, the average coefficient of variation increased as well, from 7.6% for internal to 32.6% for external. This sensor response exceeds reported environmentally induced variations in printed sensors and thus represents a promising candidate for condition monitoring. Further work is required to demonstrate actual damage detection capabilities and assess long-term stability under environmental and cyclic loading conditions. Full article

Constant current/voltage (CC/CV) output of wireless power transfer (WPT) systems deviates due to increased load resistance during charging and mutual inductance variations caused by misalignment. Dynamically regulating the DC input voltage can maintain a stable output at the preset value, and predicting the mutual inductance and load resistance can help monitor charging status. However, joint prediction of characteristics and regulation degree can be nonlinear and complicated. This work proposes a data-driven method for characteristic prediction and output optimization for WPT systems based on the current waveform from only the transmitter side. A Multi-Scale Parallel Convolutional (MSPC) neural network is applied to simultaneously predict the load resistance, mutual inductance, output deviation factor and regulation coefficient. By leveraging its multi-scale feature extraction capabilities, it can accurately estimate the aforementioned parameters based on only the AC current waveform at the transmitter side. To improve the model’s generalizability under practical conditions, transfer learning (TL) is utilized to minimize the discrepancy between simulated and physical data. Finally, a 140 W prototype of the series-series (SS)-compensated WPT system is built to validate the effectiveness of the proposed method. Full article

Protein phosphatase PPM1A plays a critical role in cellular signaling by dephosphorylating key regulatory proteins. According to experimental data, the enzyme requires either Mn²⁺ or Mg²⁺ bound in the active center(s), hence its catalytic activity strongly depends on the chelated metal ions. In this study, the metal ion selectivity of PPM1A is investigated using DFT calculations on active site constructs of bi- and trinuclear metal centers and protein ligands from the first and second metal coordination shells. Binuclear Mn-Mn and trinuclear Mn-Mn-Mn sites show poor resistance to substitution by biogenic Fe²⁺ and Zn²⁺, with Gibbs energies of the Mn²⁺ → Fe²⁺/Zn²⁺ exchange being consistently negative in both the gas phase and condensed media. In contrast, Mg-Mg and Mg-Mg-Mg centers are substantially more robust, with a thermodynamically unfavorable Mg²⁺ → Fe²⁺/Zn²⁺ substitution—except in the case of the Mg-Mg-Zn complex. The primary factors governing this metal competition in the modeled structures are the nature of the competing cation and the solvation properties of its aqua complexes, while solvent exposure of the binding site and the number of metal cations in the catalytic center exert a comparatively minor effect. Overall, these findings demonstrate that Mg²⁺-loaded active sites offer considerably greater protection against biogenic metal displacement than their Mn²⁺ counterparts, thus shedding light on the metalloprotein stability and enzyme fidelity of PPM1A. Full article

Against the background of observed climate change, which increases the risk of glacier-system degradation and the formation of hidden crevasses, the development of lightweight, wideband, and highly directional antenna systems has become a key factor in ensuring the safety of logistics operations and enhancing the spatial resolution and interpretability of ground-penetrating radar monitoring of near-surface snow–ice layers. The effectiveness of such systems is largely determined by the characteristics of the antenna unit, including the operating frequency band, gain, radiation pattern, weight, and resilience under extreme climatic conditions. The aim of this review is to provide a systematic analysis of modern Vivaldi antenna designs and Vivaldi-based antenna arrays, as well as to assess their prospects for application in X-band ground-penetrating radar systems for probing Antarctic snow-ice media. The paper considers the main types of ground-penetrating radar (GPR) antennas, their advantages and limitations, substantiates the priority of detecting hazardous near-surface inhomogeneities, and analyzes the capabilities of the X-band for the high-resolution identification of these inhomogeneities. Particular attention is paid to modern modifications of Vivaldi antennas, including antipodal, balanced, director-loaded, metamaterial-based, and array configurations. The analysis shows that Vivaldi antennas represent a promising basis for lightweight, wideband, and directional GPR systems; however, they require further improvement in terms of gain enhancement, sidelobe and back-lobe suppression, radiation-pattern stabilization, and adaptation to Antarctic operating conditions. Future research should focus on the development of adaptive and phased Vivaldi arrays, the use of metamaterials, Electromagnetic Band-Gap/Frequency-Selective Surfaces (EBG/FSS) structures, and director elements, the creation of lightweight, frost-resistant substrate materials, the advancement of multi-polarization multiple-input multiple-output (MIMO) systems, and the integration of antenna arrays with synthetic aperture radar (SAR) processing adapted to a multilayer snow–ice medium. Full article

Power system parameters are susceptible to multiple influencing factors such as environmental conditions and load current, with line parameters being notably affected. This compromises the accuracy of power flow calculation and fault analysis, and can significantly undermine the reliability of protection schemes. To address these limitations, this study proposes an integrated correction method for power system line parameters via a framework that combines soil resistivity inversion and multi-factor sag calculation. First, based on fault-recording data from external line faults, sequence impedance parameters are calculated using a two-terminal impedance difference subtraction strategy, followed by the inversion of soil resistivity along the transmission corridor. Second, considering the spatial inhomogeneity of the transmission corridor, a sliding-window statistical method is applied to segment the line, and a piecewise series model is employed to correct the zero-sequence impedance parameter. Finally, a conductor temperature and sag model based on the heat balance equation is established. By coupling ambient temperature, wind speed, solar radiation, and mechanical load, the ground capacitance and susceptance parameters are dynamically corrected. Simulation results demonstrate that the proposed framework can systematically achieve dynamic correction of power system line parameters and significantly reduce calculation errors. The developed method provides an effective technical pathway for enhancing the accuracy of power system simulation and improving the reliability of protection schemes. Full article

During heavy oil development, the gathering and transportation of low-temperature wellhead-produced fluids are often accompanied by high viscosity, pipe-wall deposition, and high flow resistance, threatening the continuous and stable operation of gathering systems. Existing studies on wellhead heating mainly focus on overall steady-state heating performance, while variable-flow heat transfer and start–stop control in local heating systems remain insufficiently explored. This study aims to evaluate the steady-state heating capacity, transient thermal response, and start–stop control performance of a localized electric heating section under variable-flow conditions. A 3D fluid–solid-coupled heat-transfer model of the heating element, pipe wall, and internal fluid was developed using COMSOL Multiphysics. The steady-state temperature field, transient heating and cooling behavior, and start–stop control characteristics were analyzed under different flow rates. The results show that, at a heating power of 15 kW and a flow rate of 20 m³/d, the maximum outer-wall temperature reached 564 K, and the average outlet fluid temperature reached 308.83 K, indicating effective heating performance. As the flow rate increased from 10 m³/d to 30 m³/d, the maximum pipe-wall temperature and fluid temperature rise both decreased, whereas the average fluid-side heat-transfer coefficient increased from approximately 700 W/(m²·K) to 1800 W/(m²·K), demonstrating enhanced convective heat transfer. Under a dual-threshold control strategy of 463.15–483.15 K, the system maintained the target temperature near 473.15 K under all tested conditions, while the load factor increased from 37.83% to 86.15%. These findings provide theoretical references and engineering support for optimizing power configuration and improving temperature control strategies in local heating systems for wellhead-produced fluids. Full article

Large civil infrastructures, including high-rise buildings, bridges, offshore platforms, transmission towers, tall chimneys, basements below the water table, etc., are often supported on pile foundations. Apart from the usual dead loads and live loads imposed by superstructures, these piles are often subjected to significant uplift forces due to overturning moments or hydrostatic pressure resulting from the effects of wind and wave loading, traffic movement, buoyancy, etc. Piles that withstand tensile loads are termed tension piles. Since the soil is unable to resist tensile stress, the pullout loads imposed on tension piles are prevented primarily by downward skin friction at the pile–soil interface, as well as by the self-weight of the piles. In this paper, a numerical model was developed using boundary element analysis, wherein piles were assumed to be made of an elastic–perfectly plastic material, and the soil was modeled using a parabolic model. The developed model was validated with available experimental results, and acceptable agreement was found. An in-depth study by detailed parametric analysis revealed that the parabolic soil model yielded satisfactory results. Extensive full-scale case studies were also performed to study the influence of various factors on tension pile performance. A set of important conclusions was drawn from the entire work. Full article

In the design of structural wind resistance, it is necessary to consider the combination of load effect extremum caused by each wind component. The existing combination rules for Gaussian wind load effects are not applicable to the combination of non-Gaussian wind load effects. The Hermite polynomial transformation model is employed to transform the non-Gaussian wind effect process based on a potential standard Gaussian process in this paper. The probability distributions of the non-Gaussian wind effect process and the non-Gaussian peak factor are deduced. A simplified TR1 (Turkstra) combination equation for the two-component non-Gaussian wind effect process and a numerical integration expression for the TR2 combination rule are proposed. The improved simplified CQC (complete quadratic combination) equations for two-component non-zero-mean softening and hardening non-Gaussian wind effect processes are derived. The accuracy and validity of these simplified combination equations are verified using the Monte Carlo simulation method. Full article

To tackle the development of large-capacity titanium shell batteries, resistance spot welding was performed to join 1 mm thick TA2 titanium plate and T2 copper plate with a tungsten electrode on the copper side and a CuCrZr alloy electrode on the titanium side. The microstructure of the interfacial zone of the joint was systematically observed and analyzed, and the tensile shear bearing capacity of the joint was evaluated. At the interface zone in the peripheral region of the weld, a CuTi layer was formed adjacent to the titanium side, and a Cu₄Ti layer was formed adjacent to the copper side; at the interface zone in the central region of the weld, four layers—CuTi₂, CuTi, Cu₄Ti₃, and Cu₄Ti—were formed. The tensile shear load of the joint exhibits a trend of initially increasing and subsequently decreasing as the welding current increases or the welding time extends, and the tensile shear load of the joint reaches the maximum value of 5.50 kN when the welding current is 18 kA and the welding time is 400 ms. The research findings suggest that despite the feasibility of resistance spot welding between titanium and copper by utilizing tungsten electrodes on the copper side, the intermetallic compound layer formed at the welding interface serves as the crucial factor influencing the performance of the joint. Full article

To explore the fracture performance and crack propagation mechanism of basalt fiber (BF)-reinforced asphalt mixtures and overcome the limitations of single-factor performance evaluations, this study systematically investigates the effects of aggregate gradation, material scale and test conditions on fracture behavior. The semi-circular bending (SCB) test was integrated with digital image correlation (DIC) technology to synchronously obtain macroscopic fracture parameters and full-field displacement/strain fields. The findings showed that fine aggregate particle size could better utilize the bridging effect of BFs, increasing fracture energy by 25.8% versus 15.9% for the coarse aggregate particle size. A consistent enhancement in fracture performance is observed between the asphalt mixture and the asphalt mortar after BF incorporation. Under the same test conditions, the addition of fibers increased the fracture energy by 25.8% for the mixture and by 28.4% for the mortar, while fracture toughness increased by 6.9% and 8.3%, respectively. The lower loading rate reduces the reinforcement effect due to viscoelastic stress relaxation, while low temperatures enhance the relative crack resistance efficiency of BFs. The incorporation of fibers increases the crack tortuosity coefficient by a range of 4–14%, leading to greater energy dissipation. However, low temperatures absolutely dominate the crack morphology. This study provides an experimental reference for the differentiated design of BF-reinforced asphalt mixtures under different gradation types and climatic conditions. Full article