Search Results (718)

Hydraulic synchronous jacking technology is extensively employed in bridge reconstruction and new construction, with jacking supports serving as core components whose blast resistance is critical to the structural safety of the bridge jacking system. This study numerically investigates the dynamic response and damage behavior of bridge jacking supports subjected to under-deck gas explosion loading through the finite-element software LS-DYNA. The TNT equivalent method is adopted to convert gas explosion load into equivalent TNT detonation load for simulation, and the effects of TNT detonation location on the blast-resistance performance of the jacking support are analyzed. The results indicate that the bridge segment temporarily loses contact with the jacking support under the action of gas explosion loading. The bridge segment around the web plate undergoes shear damage because of the deformation constraint effect of the web plate. The shear damage level of the bridge segment increases with the increase in TNT mass. The displacement of the jacking support increases with the increase in the mass of the explosive. The enhanced rod around the edge steel pipe support is more prone to damage due to its low local stiffness. The damage level of the bridge segment increases with the decrease in the distance between the TNT detonation and the bridge segment, and then the blast-resistance performance of the jacking support is almost unrelated to the vertical distance. The transverse distance between the TNT detonation and the jacking support has a significant effect on the response of jacking support. Full article

In order to improve the poor wear resistance and adhesive wear of 7075 aluminum alloy under dry friction conditions, a nanosecond pulse laser was used to prepare surface micro-textures with different shapes, surface densities, and feature sizes. Subsequently, their friction and wear behavior, as well as the corresponding failure mechanisms, were systematically investigated. Circular, square, and hexagonal micro-pit textures were selected as the research objects. Combined with surface morphology characterization, ball-on-disk dry wear tests, reciprocating friction tests, and contact stress and wear model analyses, the effects of texture parameters on tribological performance were systematically revealed. The results indicate that laser microtexturing can reduce the coefficient of friction on the surface of 7075 aluminum alloy to a certain extent and improve its wear resistance, with the friction-reducing effect closely related to the texture shape, areal density, and feature size. Among these, hexagonal texturing exhibited the best friction-reducing effect, while circular texturing demonstrated superior formation quality and friction stability. Compared to other specimens, the T8 group with a 7.5% areal density and a feature size of 100 µm exhibited the lowest average coefficient of friction. During the friction process, the microstructures gradually fail due to plastic flow filling, wear debris accumulation, and edge collapse. The research findings provide a reference for the optimized design and engineering applications of surface microstructures on aluminum alloys. Full article

With the rapid development of high-end equipment manufacturing, the number and size of complex surfaces continue to increase. Five-axis machining has become the dominant machining method. Effective prediction of cutting force and stability is of great significance for improving machining efficiency and quality. However, due to the complex and time-varying cutting geometry in five-axis machining of complex surfaces, low prediction efficiency has become a key issue restricting the research and engineering application of cutting force and stability. To address this issue, this study introduces the concept of dimensional compression and establishes an efficient prediction model for cutting force and stability. Each tool position along the tool path is discretized into inclined plane milling based on finite difference, thereby simplifying the research object. The tool twist angle and feed deflection angle are defined to describe the spatial relationship in five-axis machining. Using these two angles as new basis variables, a compressed space is constructed, and a mapping relationship between tool position and spatial point sets is established, further reducing the dimensionality of the research object. The cutting edge contact interval is determined using the spatial constraint method. Based on the full discretization method, the cutting force and stability of inclined plane milling are predicted, and the results are uniformly stored in the compressed space to form a sample point library. Consequently, the prediction process of complex surface five-axis machining is transformed into a process of sample point retrieval, significantly improving computational efficiency. Cutting force and vibration experiments in five-axis machining of complex surfaces are conducted. The results show that the predicted results are in good agreement with the experimental measurements, validating the accuracy of the proposed model and demonstrating its capability to guide practical machining. Full article

Robotic belt finishing of turbine-blade edges is difficult to control because local edge radius, contact compliance, and the incoming profile state jointly affect the final residual profile error. This study develops a sensor-derived, mechanism-informed framework for predicting section-level root-mean-square (RMS) residual profile error. Online force measurements, robot and process records, CAD-derived edge geometry, and coordinate measuring machine (CMM) profiles are converted into interpretable section-level descriptors. Three coupled descriptors are introduced to represent the load-to-radius ratio, the force–radius-mismatch interaction, and the normalized radius mismatch. Four Gaussian process regression (GPR) configurations, a training-mean predictor, and a ridge-regression baseline are evaluated using a grouped leave-one-blade-out protocol on eight blades and 80 measured sections. The proposed descriptors show clear predictive value under blade-wise evaluation. Ridge-B3 achieves the best deterministic accuracy, with RMSE = 1.0285 µm and R² = 0.7759. The predefined GPR-B3 model does not provide the lowest point-prediction error, but it provides predictive intervals and descriptor-attribution information. These results indicate that descriptor construction is the primary source of deterministic accuracy, whereas GPR serves as an uncertainty-aware modeling layer for risk-aware blade-edge quality assessment. Full article

Rockfall from slope unstable rock masses is a typical geological hazard induced by brittle failure, with abrupt occurrence, limited macroscopic deformation before failure, and a short warning lead time. Conventional static analysis methods are useful for design-stage stability checks, but they cannot continuously capture structural-plane damage or update the stability state in real time. Dynamic evaluation based on structural dynamics links measurable parameters such as natural frequency, damping ratio, mode shape, vibration trajectory, wave velocity, and energy dissipation to the degradation of structural planes. This review synthesizes the dynamic behavior mechanism, parameter system, theoretical models, sensing technologies, and engineering applications for slope unstable rock masses. Different from previous reviews that mainly summarize rockfall monitoring or conventional slope stability analysis, this paper organizes the literature by failure mode, monitoring scale, model assumptions, field validation, uncertainty sources, and engineering applicability. The single-degree-of-freedom models for sliding-, toppling-, and falling-type rock masses, multi-block chain-collapse models, and data-physics dual-driven surrogate models are compared critically. Contact monitoring based on MEMS sensors, non-contact LDV monitoring, acoustic emission, microseismic monitoring, coda wave interferometry, and cloud-edge early-warning architectures are further reviewed. Key challenges include field-scale validation under heterogeneous and anisotropic geological conditions, environmental compensation, robust threshold calibration, and probabilistic linkage between dynamic indicators and failure probability. The review provides guidance for selecting dynamic evaluation models, designing field monitoring systems, and developing full-life-cycle digital-twin platforms for rockfall risk mitigation. Full article

Silver conductive structures were fabricated on 96% alumina ceramic substrates by selectively irradiating a silver nitrate precursor liquid film using a 355 nm Nd:YAG nanosecond laser under ambient conditions, without the use of external reducing agents. The effects of laser energy density, scan number, precursor concentration, plasma pretreatment, and PVP-30 addition on the morphology, composition, electrical conductivity, and adhesion of the deposited structures were investigated using XRD, SEM, EDS, contact angle measurements, resistance measurements, and tape-peeling tests. XRD confirmed the formation of metallic Ag in the laser-scanned regions. Insufficient laser energy density led to incomplete Ag⁺ reduction and discontinuous conductive paths, whereas excessive energy input caused hollow formation and Ag edge accumulation. A laser energy density of 12.03 J/cm² provided a favorable balance among structural integrity, Ag enrichment, and electrical conductivity. Increasing the scan number promoted particle coalescence and conductive network formation, while 1000 scanning cycles provided a suitable balance between structural continuity and dimensional precision. As the AgNO₃ concentration increased, the deposited structures evolved from isolated particles into continuous and compact layers, with 5 mol/L showing favorable deposition performance. Plasma pretreatment combined with PVP-30 addition reduced the contact angle of the ceramic surface from 48.25° to 19.05°, thereby improving the continuity, uniformity, and compactness of the deposits. After the scan spacing was reduced to form continuous silver films, the samples retained more than 98% of their conductivity after five tape-peeling cycles, with a resistivity of 6.14 × 10⁻⁸ Ω·m. These results demonstrate that laser-induced deposition is a controllable strategy for fabricating conductive silver structures on ceramic surfaces. Full article

We describe a GPU-resident execution pipeline for explicit large-deformation finite element analysis in which every stage of the timestep—internal force evaluation, contact processing, nodal update, time integration, and minimum edge-length reduction—operates on arrays that remain in device memory, so per-step bulk transfers across PCIe are avoided. Contact is handled on the device through a shared-memory brute-force proximity search with warp-ballot stream compaction. We exercise the solver on a hemisphere compression benchmark at six mesh resolutions (83 K–1.89 M elements). On an NVIDIA L40, per-step speedups over a single CPU core range from about 99× to 138×, increasing with problem size and approaching a plateau near 137× for the largest meshes (above roughly 1 M elements); the contact-enabled configuration adds a net ON/OFF overhead of +13% to +21% to the step time. Against LS-DYNA running in SMP mode on the same problem, the proposed solver is roughly 94× faster than the best 8-core configuration, a margin consistent with the multicore saturation observed in the SMP measurements. The remaining limitations—single-GPU execution, FP32 arithmetic, and rigid-body contact search without a BVH broad phase—are identified as specific targets for multi-GPU, mixed-precision, and scalable-contact extensions. Full article

The spread of infectious diseases on heterogeneous contact networks poses significant challenges for designing effective and cost-efficient intervention strategies. In this work, we investigate optimal epidemic control for a network-based SIR model by explicitly incorporating network topology into the control design. A structurally critical subset of transmission pathways is first identified using a hub-distance-based backbone extraction algorithm, which isolates influential edges associated with highly connected nodes. A global edge-disconnection control acting on this subset is then introduced, and the epidemic mitigation problem is formulated as a continuous-time optimal control problem. By applying Pontryagin’s Maximum Principle, we derive the complete set of necessary optimality conditions and characterize the optimal control via a scalar Hamiltonian minimization involving a time-dependent sensitivity function. Analytical results establish the monotonicity of this function, implying that optimal strategies prioritize strong early intervention followed by gradual or abrupt relaxation depending on the cost structure. Numerical experiments on scale-free networks and three empirical networks demonstrate that the proposed hub-distance-based edge selection strategy, coupled with optimal time-dependent control, effectively suppresses epidemic spreading. Under the same control budget, it outperforms random edge deletion as well as classical critical edge strategies based on degree product and edge betweenness. These findings highlight the importance of network-aware interventions and provide a rigorous and interpretable framework for epidemic control. Full article

To elucidate the wear evolution and failure mechanisms of VL-type composite seals in aviation hydraulic actuators under multiple operating conditions, a two-dimensional plane-strain finite element model was developed for a VL seal consisting of a PTFE L-ring and an NBR O-ring. The model incorporated the Mooney–Rivlin hyperelastic constitutive law and the Archard wear model. The effects of O-ring compression ratio, hydraulic pressure, sliding velocity, and temperature on cumulative wear, wear rate, and contact state were systematically investigated. The results show that the compression ratio has a nonlinear influence on wear. Within 8–16%, the peak wear increases approximately linearly with compression ratio; above 16%, the peak wear reaches a plateau and a secondary wear zone appears, indicating a transition from single-contact to multi-contact sealing. Hydraulic pressure promotes wear over the range of 4–28 MPa, and at 28 MPa the opposite lip edge of the L-ring comes into contact with the cylinder wall, weakening the sealing effectiveness. Within 0.1–0.3 m/s, wear increases approximately linearly with sliding velocity. However, under high velocity and insufficient hydraulic pressure, the L-ring may undergo inversion, resulting in complete seal failure. Temperature exhibits a non-monotonic effect: material softening reduces local contact stress and wear from −55 to 80 °C, whereas excessive softening at 135 °C causes the peak wear rate to increase again. A parametric analysis scheme involving an increased L-ring height and thickness, a reduced O-ring cross-section diameter, and reserved deformation space raises the critical compression ratio for stable single-contact sealing from 16% to above 20%. These findings clarify the contact-stress/contact-area competition mechanism governing VL seal wear and provide guidance for the design of aviation hydraulic actuator seals. Full article

To enhance immersion in virtual reality (VR) environments and improve the fidelity of virtual tactile interaction, this study proposes a perceptually grounded haptic-rendering framework for fine surface-texture simulation. The framework is centred on a Perceptual Haptic Spectrum Model (PHSM), which maps virtual surface attributes, including hardness, elasticity, roughness, friction, and microtexture periodicity, to multi-band tactile targets in perceptual frequency space. A Just Noticeable Difference (JND)-inspired parameterisation strategy is used as a design guideline to avoid imperceptible or redundant actuation, while region-specific response functions adapt the output to the fingertip centre, finger pad, and lateral edge. To improve reproducibility, the revised manuscript now specifies the flexible thin-film force/strain-sensor cell, array quantity, 320 Hz per-cell acquisition setting, signal-conditioning pipeline, contact-state classification rules, delay budget, and dual-actuation scheduling logic. The sensing design is based on a commercial flexible piezoresistive force-sensor cell with microsecond-level response time and a 12-bit ADC acquisition chain that provides a sufficient aggregate sampling margin for a 7–21 cell array. Manufacturer-supported sensor performance and prototype-level acceptance criteria are reported for response time, linearity, repeatability, hysteresis, drift, SNR, contact-state detection, latency, and durability. The system remains a proof-of-concept platform rather than a completed large-scale psychophysical validation. Within these boundaries, the results show coherent integration of perceptual modelling, multi-rate sensing, state monitoring, predictive feedforward control, and coordinated haptic actuation for fine VR texture rendering. Full article

Conductive polymer composites with a segregated structure are a promising route to obtaining electrically active materials at low filler loadings. In this work, aminated graphene (AmG) was used as a functional conductive filler for the fabrication of composites with a segregated structure based on polyvinyl chloride (PVC) and poly(vinylidene fluoride-co-tetrafluoroethylene) (P(VDF-TFE)). AmG was comprehensively characterized by electron microscopy, core-level and near-edge spectroscopy, optical spectroscopy, and electrical measurements. The synthesized AmG contained 14.34 at.% nitrogen, with amines accounting for 81.44% of the nitrogen-related spectral intensity, corresponding to an amine concentration of 11.78 at.%. AmG also exhibited a restored π-conjugated network, intrinsic conductivity of 20–33 S/cm, and a crumpled-flake morphology favorable for interfacial contact with polymer particles. At a filler loading of only 1 wt.%, the segregated composites reached electrical conductivity up to 1.3–1.4 × 10⁻⁴ S/cm, exceeding those of the unfilled polymers by seven orders of magnitude. At 11 GHz, the AmG-filled P(VDF-TFE) composite showed 15.1 dB attenuation for a theoretical thickness of 30 mm, transmitting no more than 3% of the incident radiation. These results identify AmG as a functional conductive filler for segregated electrically conductive polymer composites and demonstrate that the combination of amine-containing surface chemistry, restored electrical conductivity, and crumpled morphology enables conductive interparticle network formation in PVC- and P(VDF-TFE)-based composites at only 1 wt.% filler loading. Full article

Infestation by boring sponges poses a serious problem for Pacific oyster Magallana gigas (Thunberg, 1793) aquaculture. This study aimed to assess the effect of Pione vastifica sponge infestation on the oysters’ capacity for shell repair, antioxidant defence status, and hemocyte functional state. We analysed the expression of VEGF pathway genes and biomineralisation enzymes, molecular chaperones (Hsp70, Hsp90), growth arrest and DNA damage gene (Gadd45α), antioxidant enzyme activity and lipid peroxidation levels in the hemolymph and various mantle parts (central and outer-edge). Intracellular reactive oxygen species (ROS) levels and mitochondrial membrane potential in hemocytes were evaluated. The results showed that infection significantly increases intracellular ROS levels in hemocytes without changing mitochondrial membrane potential. Oxidative damage was localised primarily in the central mantle contacting the damaged shell. In the outer-edge mantle responsible for shell growth, marked upregulation of SodMn, Cat, and Gadd45α was observed, coupled with suppression of VEGF-R receptor expression and organic matrix genes. Heat shock protein expression decreased in all examined tissues of infected molluscs. Our results demonstrate that shell damage induced by boring sponges triggers a tissue-specific reorganisation of physiological priorities, manifesting as a bioenergetic trade-off where limited energy resources are reallocated from the ATP-demanding process of biomineralisation to sustain antioxidant defence and cell survival. Full article

This work investigates the performance improvement of a four-probe ballistic rectifier on bilayer graphene (BLG) through the formation of an energy gap under a perpendicular electric field. For this purpose, exfoliated BLG was deposited on oxidized n⁺-Si and structured into an asymmetric cross junction with 90 nm wide channels. The junction consists of a straight voltage stem (contacts U, L) and slanted current injectors (contacts 1, 2). The differential conductance of the stem, g_UL, as a function of back-gate bias, V_BG, reveals clear indications of energy gap formation and lateral depletion zones at the edges of the channel. The DC characteristic of the ballistic rectifier, V_UL(I₁₂), shows an increase in the output voltage V_UL with increasing V_BG. We attribute this to reduced diffuse scattering at the rough edges when the lateral depletion zones form smooth barriers. Full article

In this study, we introduce a novel method for microscale viscosity measurement that eliminates the need for direct contact angle determination. By utilizing a capillary with a sufficiently small radius (R < 0.2 mm), the sharp outlet edge pins the three-phase contact line, stabilizing the apparent contact angle near 90° and nullifying the capillary pressure term. The rheological parameters (K and n) of power-law fluids are then calculated directly by analyzing image sequences of a growing pendant droplet to obtain its volume flow rate Q. Experiments verify through inversion calculation that the apparent contact angle indeed converges to 90° at a small capillary radius. The proposed method is employed to measure 20 wt% and 40 wt% glycerol aqueous solutions (Newtonian fluids) as well as 0.01 wt% and 0.02 wt% xanthan gum aqueous solutions (non-Newtonian fluids). The obtained rheological parameters agree well with reference values within this range, confirming the method’s reliability for these low-viscosity and moderately non-Newtonian fluids. However, measurements on higher concentration fluids (e.g., 0.1 wt% and 0.2 wt% xanthan gum solutions) reveal increased errors, indicating a current limitation in accurately characterizing fluids with high viscosity or pronounced non-Newtonian behavior under gravity-driven flow. This simple technique provides a reliable and low-cost approach for measuring the viscosity of microliter-volume fluids within its characterized operational range. Full article

Floating rafts are thin, flat mineral layers that precipitate at still air–water interfaces. They are composed of calcite, aragonite, vaterite, gypsum, trona, carnallite, and/or halite. Floating rafts present a flat surface at the top in contact with air, and a rough surface at the bottom, which develops as they grow into the water. In this work, we describe floating rafts from hypersaline environments using imaging and analytical microscopy techniques. The four rafts studied consist of interconnected polycrystalline grains. Scanning electron microscopy (SEM) showed that the top surfaces were flat, whereas in the bottom surfaces, the grains protrude into the water. High magnification revealed nanoparticles arranged in stacks, suggesting growth through the organized agglutination of nanocrystals. Electron diffraction of two of the rafts indicates that they consist of aragonite. Accordingly, electron energy-loss spectroscopy (EELS) shows the C K-edges characteristic of carbonates, along with O and Ca edges. Energy-dispersive spectroscopy (EDS) in the SEM also revealed a few Ca sulfate crystals on the bottom surface. In addition, the presence of cubic shapes indicates the presence of halite. We hypothesize that the genesis of these rafts is driven by evaporation of still water, which increases supersaturation at the very surface, leading to mineral nucleation at the air–water interface, where the activation energy is lower. Full article