Search Results (9,498)

This study devised a blasting experiment to establish a dynamic quantified relationship between blasting and movement, failure, and ejection of rock masses. The experiment was conducted using the 3D digital image correlation method (3D-DIC), which provided high-speed images capturing the process of shallow-buried tunnel blasting. The study analyzed the mechanical behavior of full-section rock mass under blasting action through cross-scale image processing. Yield and elastic points were distinguished based on the time–displacement curve. Then, the spatial vector method was employed to deduce flying rock trajectory and throwing distance, enabling the subdivision of underground space based on risk assessment. The results show that the rock in the cut zone starts moving within 3 ms after initiation, ultimately exhibiting a maximum visible off-plane displacement of 215 mm. Displacements are related to delay time and distance. Different zones show distinct dominant directions of rock mass displacement. The rock mass becomes flying rocks separated from the cross-section. The initial velocity of the flying rocks ranges from 11.8 m·s⁻¹ to 29.9 m·s⁻¹. Around 85% of the flying rocks fall within the range of 0 to 40.8 m. Only 5% of the flying rocks fall outside 64.3 m. Appropriate protective measures should be taken for equipment during experiments. Full article

With the expansion of urban underground space, the structural safety of underground infrastructure has become increasingly critical. The urban underground utility tunnel is a typical deeply buried lifeline project. Its internal environment is humid and confined, and the structure is subjected to long-term heavy loads and earth pressure. Under such conditions, micro-cracks readily propagate into leakage channels and eventually cause structural damage. However, the slender morphology, low contrast, and complex background of cracks make it difficult for traditional inspection methods and general-purpose models to achieve reliable identification and accurate segmentation. This study proposes a two-stage framework that combines YOLOv8 with SAM2 and incorporates a coordinate attention module for high-quality crack segmentation. For image processing, a topology-aware post-processing strategy is introduced, together with a scoring function based on crack morphological features and a post-processing constraint mechanism, to ensure crack continuity and geometric consistency and to mitigate the over-segmentation that may occur during segmentation. YOLOv8-SAM2 achieves 85.2%, 90.5%, 77.2%, and 71.6% in mIoU, mDice, Recall, and Precision, respectively. Compared with YOLOv8-seg, mIoU and Precision are improved by 46.3 and 17.2 percentage points, respectively; compared with the baseline SAM2, mIoU and Precision are improved by 23.0 and 16.9 percentage points, respectively. In summary, on the self-built underground utility tunnel crack dataset, the proposed model significantly outperforms standalone YOLOv8 segmentation and the direct application of SAM2 in terms of intersection-over-union and precision, demonstrating its high-quality segmentation capability. Full article

Electrostatic spraying improves droplet deposition on the undersides of leaves and within canopy-obscured regions. However, existing studies mainly rely on two-dimensional trajectory analyses or simplified computational fluid dynamics (CFD) models, limiting the mechanistic understanding of the three-dimensional transport behaviour of charged droplets. To address this limitation, an integrated analytical framework combining theoretical droplet dynamics, CFD–DPM simulations, high-speed imaging, and wind-tunnel experiments was developed. Within this framework, a three-dimensional trajectory-tracking method was established to quantitatively characterise the electrostatic envelopment effect using measurable transport parameters, including droplet trajectories and effective electrostatic envelopment distance. Numerical simulations and experimental evaluations were combined to analyse the relationships among three-dimensional droplet transport, electrostatic envelopment, and leaf deposition performance. Results showed that deposition efficiency reached 15.92% at an induction voltage of 12 kV, representing an increase of 13.94 percentage points compared with uncharged spraying. Crosswind speed was the dominant factor affecting deposition, followed by induction voltage and spray pressure. The effective electrostatic envelopment distance was approximately 2.1 cm. The proposed framework enables quantitative characterisation of electrostatic envelopment and provides a mechanistic basis for analysing the relationship between three-dimensional droplet transport and deposition performance, offering a framework for electrostatic spraying evaluation and operating parameter optimisation. Full article

To address delayed attitude correction, limited adaptability of single-actuator systems, and reduced tunneling efficiency in full-face shaft-boring machines (SBMs), this study proposes a PSO-LSTM-based hybrid steel strand–support shoe attitude correction strategy. A coupled dynamic model with a 45° offset configuration is developed to enable coordinated multi-actuator control. A PSO-optimized Long Short-Term Memory (PSO-LSTM) network is employed to predict inclination deviation over a 5 s horizon, providing anticipatory information for proactive control. Based on this prediction, a hierarchical control strategy with adaptive torque allocation is designed to seamlessly coordinate fine correction via steel strand cables and high-torque correction via support shoes. Simulation results demonstrate that the proposed model achieves a prediction accuracy within ±0.02°. Under inclination conditions of 0.05°, 0.3°, and 1.0°, rapid attitude correction is achieved. Compared with independent support shoe control, the maximum horizontal displacement is reduced from 64 mm, 131 mm, and 160 mm to 6.3 mm, 65 mm, and 100 mm, corresponding to reductions of 90.2%, 50.4%, and 37.5%, respectively. The results further indicate that small-angle deviations can be compensated by the steel-strand system without additional support-shoe operations, while medium- and large-angle deviations can be regulated through coordinated actuation of multiple correction systems according to deviation magnitude. Simulation results demonstrate that the proposed method improves attitude correction performance and dynamic response under the investigated simulation conditions. The proposed framework provides a potential solution for intelligent attitude control of SBMs, while further field validation is required before practical engineering deployment. Full article

The Co₄₀Fe₄₀B₂₀ alloy is a key magnetic material that combines high saturation magnetization with excellent soft magnetic properties, offering broad application prospects in fields such as spintronic devices, magnetic tunnel junctions, and tunnel magnetoresistive sensors. Hot pressing can be used to produce fine-grained, highly dense CoFeB alloys. However, there is currently a lack of systematic research on the intrinsic mechanisms by which the particle size of gas-atomized CoFeB powders and their non-equilibrium solidification microstructure regulate phase transformations, microstructural evolution, and densification behavior during hot pressing and sintering—particularly regarding the microstructural inheritance effects of powders with different particle sizes. To address this issue, this study used vacuum induction melting and gas atomization technology to prepare Co₄₀Fe₄₀B₂₀ pre-alloyed powders in three particle size ranges: <38 μm, 38–74 μm, and 74–154 μm. Under identical process parameters, corresponding bulk alloys were produced via vacuum hot-press sintering, and the effects of initial powder particle size on phase transformations and microstructural evolution in the sintered bodies were systematically investigated. Microstructural characterization revealed the complete phase evolution of the alloy from the non-equilibrium solidified powder state to the sintered equilibrium state. During hot-press sintering, the metastable (Fe,Co)₃B phase in the powder completely decomposed, transforming into a stable body-centered cubic bcc-(Fe,Co) phase and a bcc-(Fe,Co)₂B second phase. The dispersed (Fe,Co)₂B phase precipitated after sintering strongly inhibits grain boundary migration via the Zener pinning effect, effectively hindering grain growth and resulting in a uniform, fine-grained, equiaxed microstructure. In coarse powders, due to the presence of a portion of the (Fe,Co)₂B phase, this phase aggregates and grows during sintering, weakening the pinning effect and leading to abnormal grain growth. The Hall–Petch fine-grain strengthening effect resulting from grain refinement couples with and offsets the weakening of second-phase strengthening caused by second-phase coarsening, ultimately leading to sintered bodies prepared from powders of different particle sizes exhibiting similar macroscopic density and hardness properties. Full article

The accuracy of the numerical simulation of unsteady cloud cavitation around a hydrofoil depends on the combination of the cavitation model, the Reynolds-Averaged Navier–Stokes (RANS) turbulence model and the exponential coefficient n of the Reboud’s correction. To assess the influence of such choices, three turbulence models, three cavitation models and two values of n have been combined to predict the shedding frequency and the morphology of cloud cavitation around the NACA65012 and NACA0009 hydrofoils. The comparison with analogous experimental results obtained in a cavitation tunnel indicates, firstly, that the same numerical set-up differs in accuracy depending on the hydrofoil geometry. Secondly, within the scope of the two tested hydrofoils and corresponding flow conditions, the Shear Stress Transport (SST) turbulence model and the value of n = 10 appear to be more accurate and more robust for all tested cases. And finally, the predicted shedding frequency is more sensitive to the selection of the turbulence model than to the cavitation model. If an erosion model is implemented, then it is found that the predicted potential energy distribution of the cavitating flow is sensitive to the selected cavitation model. In our case, the Sauer model gives a more accurate distribution and intensity of erosion power than the rest of the cavitation models. Full article

During the floating transportation and installation of immersed tube tunnels, the mechanical stability of the mooring system is a key factor governing construction safety. Current conditions and mooring-line arrangements are two major factors controlling the magnitude and distribution of mooring-line tensions. However, their coupled effects and the applicability of different calculation methods remain insufficiently understood. Based on a large-cross-section immersed tube tunnel project, this study employed a semi-empirical method specified in the Chinese Code for Loads on Port Engineering and a three-dimensional floating-body-mooring numerical model established in ANSYS AQWA. Multiple combinations of current velocity and direction were considered to compare the mooring-line responses under five typical arrangements corresponding to different construction stages. The effects of current conditions and mooring configurations on the magnitude, distribution, and transfer of mooring-line loads were systematically examined. The results show that current velocity is the dominant factor controlling the magnitude of mooring-line tensions, which generally increase with the square of the current velocity. Changes in current direction directly alter the principal load-bearing mooring-line group, and a current velocity of 1.5 m/s during the falling tide represents the most unfavorable current condition throughout the construction process. The mooring-line arrangement governs the spatial distribution and concentration of the line loads. During the floating transportation and mooring stages with multi-line constraints, the maximum mooring-line tensions calculated using China’s code-based method are 18.5–25.2% higher than those obtained from the numerical simulations, indicating relatively conservative predictions. In contrast, during stages with weakened constraints, such as line release and positioning in the foundation trench, the numerical model captures more pronounced local load concentration, yielding maximum tensions 19.4–28.8% higher than those predicted by the code-based method. Across all operating conditions, the maximum mooring-line tensions calculated by the code-based method and numerical model are 924 and 750 kN, respectively. This study clarifies the coupled effects of current conditions and mooring-line arrangements on mooring-load transfer and identifies the applicable scenarios of the two calculation methods. The findings provide a quantitative basis for calculation-method selection, mooring-force assessment, and construction-safety management during immersed tube tunnel installation. Full article

Background and Objectives: Lateral extra-articular tenodesis (LET) is increasingly used to augment anterior cruciate ligament reconstruction (ACLR) in selected high-risk patients. Femoral fixation strategies vary widely and may influence construct behavior, tunnel interaction, technical safety, and ultimately knee stability and functional outcomes. The objectives of this review were to map and compare femoral fixation techniques for LET performed with ACLR, to summarize the cadaveric and clinical evidence relevant to fixation choice, to synthesize imaging and experimental data on femoral tunnel convergence and collision-prevention strategies, and to propose an evidence-informed, collision-aware planning framework for femoral fixation selection. Materials and Methods: A systematic review with narrative synthesis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. PubMed/MEDLINE, Embase, and the Cochrane Library were searched from inception through February 2026. Eligible studies were classified a priori as direct LET clinical evidence, LET biomechanical evidence, LET imaging or convergence evidence, extrapolated anterolateral ligament (ALL) or broader lateral augmentation tunnel-geometry evidence, technical guidance, or contextual background. Results: Thirty-three studies met the eligibility criteria and provided extractable fixation-specific, biomechanical, imaging, or technical data. Femoral fixation techniques clustered into inlay tunnel or socket fixation, onlay cortical fixation, suspensory or indirect concepts, and alternative designs. Biomechanical and imaging studies demonstrated construct-specific differences in restraint behavior, overconstraint signals, tunnel trajectory, and convergence risk. Clinical studies reported fixation-related variation in complications and failures, although comparative fixation-specific clinical evidence remained limited and heterogeneous. Conclusions: Available biomechanical and imaging evidence suggests that the femoral fixation family, implant geometry, tunnel trajectory, and graft fixation angle may influence construct behavior and tunnel safety; however, direct comparative clinical evidence remains limited, and these observations should be interpreted with caution. The fixation taxonomy and collision-aware planning framework proposed here are intended as a structured, evidence-informed aid for describing and planning femoral fixation strategies rather than as a validated decision tool, and they highlight the need for standardized reporting of the fixation family, entry point, drilling trajectory, tunnel or socket dimensions, fixation angle, and collision-control strategy. Full article

Fully grouted rock bolts have been extensively utilized in underground reinforcement. Numerous experimental and theoretical studies have been performed to examine the short-term strength of the fully grouted rock bolts under the normal pullout test. However, the creep behavior closely associated with the long-term strength of the rock-bolting system has been rarely examined. Here, we proposed a fractional-derivative-based constitutive model to simulate the observed creep stages of the fully grouted rock bolts under the confined pullout creep condition. The model leveraged the Abel dashpot to capture the nonlinear creep and an exponentially decaying damage function to represent the accumulated deterioration in the bolt–grout interfacial strength during creep. The proposed constitutive model was validated against a series of laboratory confined pullout creep tests. The tests covered confining pressures up to 3.0 MPa and sustained pullout loads ranging from 37 to 279 kN. The analytical curves agreed closely with the measurements (R² > 0.98), indicating that the model can characterize the time-dependent pullout response of the tested bolt–grout system. Our study facilitates the underground reinforcement system design in the fields of civil and mining engineering where long-term rock-bolting service is required. Full article

Coal dust carried by open-top freight trains can undergo complex transport and redistribution in confined railway tunnels, where train-induced airflow links in-tunnel particle motion to near-portal dispersion. However, how particle size and source position jointly influence transport across the train–tunnel–portal system remains insufficiently understood. A three-dimensional transient CFD–DPM model was developed for an open-top coal train traveling at 80 km/h through a 200 m local tunnel section and adjoining portal air domains. Four controlled cases combined two prescribed particle sources—a coal-surface source and a near-ground source—with representative diameters of 10 and 350 μm. In the simulated cases, the maximum air speed over the exposed coal surface increased from approximately 24 to 39 m/s during tunnel entry. The 350 μm particles exhibited stronger inertial settling and preferential migration toward the lower tunnel, whereas the 10 μm particles were more strongly coupled to the airflow and transported toward the portal by the train wake. Under the same prescribed source strength, the near-ground-source cases produced higher source-normalized concentration responses than the coal-surface-source cases, indicating a stronger suspended-transport response for particles introduced near the tunnel floor. In the 10 μm near-ground-source case, fine particles passed through the outlet portal and formed a transient elevated plume that spread downstream and laterally. Within the prescribed-input cases examined here, the simulations illustrate the joint influence of particle size and source position on cross-region coal-dust transport and organize the transport pathways into four particle-transport regions: the coal-surface, lower-tunnel, train-wake, and near-portal regions. Full article

This study proposes a quality-aware multimodal framework for health-state assessment and remaining useful life (RUL) prediction of cold-region tunnels. The framework integrates structural-response, environmental, apparent-defect, and engineering-inspectiondata, with the apparent-defect pathway jointly encoding raw images through a convolutional neural network and structured defect variables. Five data-quality dimensions-completeness, accuracy, consistency, timeliness, and traceability are incorporated intoreliability-guided multimodal fusion. Their base weights were re-audited through two rounds of expert consultation, each comprising 323 valid questionnaires. The Cr-weighted group analytic hierarchy process yielded weights of 0.0548, 0.1326, 0.1372, 0.2279, and 0.4474, respectively, with a group consistency ratio of 0.0455; the ranking remained stable under one-at-a-time +10% perturbations. In the primary tunnel case study, the framework achieved 89.7% health-state accuracy, a 6.3% RUL mean absolute percentage error, and 84.1% accuracy under Gaussian perturbation of standardized numerical inputs at a noise scale of 0.15. To further examine the reliability contribution of data-quality information, an independent field panel comprising 600 segment-month observations from 25 segments across three operational tunnels was evaluated using target-excluded specifications, two-way fixed effects, leave-one-tunnel-out validation, multiple baseline models, and five fixed random seeds. A one-standard-deviation increase in lagged quality instability was associated with a 0.0151 increase in the subsequent state-error index (95% CI: 0.0118-0.0184; p < 0.001). In cross-tunnel random-forest tests, incorporating quality information increased mean R² from 0.8277 to 0.8323 for state-error prediction and from 0.8517 to 0.8673 for RUL-contraction prediction, with both improvements significant in paired tests (p < 0.001). Split-conformal intervals achieved mean cross-tunnel coverage of 95.8% and 95.9%, respectively. These findings demonstrate that data-quality information provides a modest but statistically supported improvement in cross-tunnel reliability, whilethe principal contribution lies in integrating auditable data governance, reliability-aware fusion, and engineering decision support within a unified tunnel health-management framework. Full article

TBM jamming in deep, weak, squeezing ground poses a persistent threat to construction safety and schedule performance. Most existing approaches evaluate shield jamming and cutterhead jamming independently, even though TBM operation is simultaneously limited by the available thrust and torque capacities. This study proposes a unified thrust–torque assessment framework that integrates the time-dependent response of weak surrounding rock, represented by the Cvisc model, with interface-based rock–TBM contact. The framework was applied to a representative Himalayan tunnel excavated by a double-shield TBM. The calculated total tunnelling resistance and cutterhead torque demand were then evaluated against the corresponding rated machine capacities. A parametric investigation covering advance rates of 0.5–2.5 m/h, over-excavation amounts of 3–9 cm, shield lengths of 12–16.5 m, and surrounding-rock elastic moduli of 2–8 GPa identified advance rate as the dominant controllable factor, contributing 61.6% of the variance in total tunnelling resistance and 96.2% of that in cutterhead torque. Increasing the over-excavation amount primarily alleviated shield–rock contact and reduced shield frictional resistance by up to 56.2%, while exerting only a limited influence on cutterhead torque. These findings were subsequently synthesised into a project-specific jamming-risk zoning matrix, which identified low advance rates combined with small over-excavation under long-shield conditions as the most unfavourable operating regime. Field validation was conducted using 10 representative operating cases satisfying η < 0.9. The calculated responses agreed well with the monitoring data, yielding R² = 0.82 and a MAPE of 12.0% for total tunnelling resistance versus field-monitored thrust, and R² = 0.72 and a MAPE of 16.3% for cutterhead torque. The proposed framework therefore provides a quantitative basis for TBM parameter selection and jamming-risk control in squeezing ground within the validated operating range. Full article

Background and Objectives: Achieving optimal soft-tissue aesthetics is a paramount challenge during an apicoectomy of the maxillary central incisors. This article presents a novel modification of the Eskici Vertical Flap, designed to minimize scar formation, preserve the architectural integrity of the sub-mucosal fibers, and eliminate the risk of marginal gingival recession. Methods: The Transfrenular-Single Incision (TrSI) flap is elevated via a precise two-step process. First, a sagittal incision is carried out through the mucosa along the midline of the maxillary labial frenulum. Blunt lateral tunnel preparation is then performed toward the targeted tooth apex, and a subsequent deep periosteal incision with bony contact provides localized access to the periapical lesion. Following Paraendodontic Surgical Intervention (PSI), a two-layer suturing technique is implemented: the deep layer utilizes resorbable sutures to restore periosteal integrity and reposition the basal fibers of the frenular connective tissue, while the superficial layer promotes accurate mucosal edge adaptation. Results: The surgical access provided by the TrSI flap provides clinically sufficient exposure to perform precise osteotomy, retrograde root-end preparation, and biocompatible sealing. The evaluated clinical cases demonstrated optimal healing kinetics, the complete absence of visible scar tissue, and zero marginal gingival recession. Conclusions: The TrSI flap modification constitutes a highly predictable and effective option for PSI in the aesthetically critical anterior maxilla. Although its application spectrum is primarily limited to the central incisors, its capacity to prevent aesthetic deformities warrants its consideration in selected surgical protocols. Full article

Small multirotor UAVs frequently operate in crosswind conditions, yet the aerodynamic interaction between windward and leeward propeller pairs remains incompletely understood. This study investigates the performance of a quadcopter propeller system under lateral crosswind using steady-state RANS simulations with the Transition SST turbulence model, validated against wind tunnel measurements (thrust and torque deviations within $5.4\%$). A parametric matrix of five rotational speeds (8000–12,000 RPM) and six freestream velocities (0–10 m/s) is systematically examined. While thrust and power coefficients of all propellers increase monotonically with freestream velocity, the figure of merit ($FM$) of leeward propellers exhibits a previously unreported non-monotonic response: it decreases from hover, reaches a minimum near $6 \mathrm{m}/\mathrm{s}$, and partially recovers at higher velocities. Windward propellers show no such degradation. Our velocity contour and streamline analyses reveal that this behavior originates from windward wake ingestion into the leeward inflow region, which peaks at intermediate freestream velocities and is progressively alleviated as the stronger crosswind convects the wake downstream. The non-monotonic $FM$ response is therefore a direct consequence of the competition between wake-induced inflow degradation and freestream-driven aerodynamic augmentation. Our findings provide a systematic aerodynamic dataset essential for crosswind attitude control and propulsion system design in multirotor UAVs. Full article

Aerosol emission and dispersion in transport corridors are central to urban air quality, human exposure assessment and transport planning. Although near-road air pollution has been widely studied, much less is known about analogous processes in rail-related environments, especially in at-grade and semi-open rail corridors. This study presents a comparative systematic mapping review of evidence on air quality, with a focus on aerosol emission, dispersion and exposure in road and rail transport corridors. The literature search was conducted in Scopus, Web of Science Core Collection and PubMed for publications published between 2000 and 28 June 2026, using a PRISMA-based screening procedure. A total of 2958 records were identified. After deduplication, 1693 records were screened, and 1431 records were retained for thematic analysis. Retained set consisted of 885 road/near-road only records, 337 rail/near-rail only records, 193 shared/comparative records and 16 records assigned to other transport microenvironments. The road literature was well developed in relation to concentration gradients, dispersion, monitoring, modelling and exposure assessment. In contrast, the rail literature was dominated by metro systems, underground railways, tunnels and underground stations, which accounted for 435 records, or 82.1% of rail-related records. Only 95 rail records addressed at-grade, open, semi-open or general rail environments. The main research gap concerns aerosol emission, dispersion and human exposure in at-grade railway, tram and light rail corridors. Full article