Search Results (9,005)

Coastal reclaimed areas are characterized by complex strata and high groundwater levels, and pile foundations in such areas often suffer from insufficient uplift resistance. Compared with conventional cast-in-place piles, squeezed branch piles exhibit superior uplift performance; however, studies on squeezed branch piles in reclaimed areas remain limited. To investigate the uplift bearing performance of squeezed branch piles in the complex strata of coastal reclaimed areas, in situ full-scale uplift tests were conducted in the Shenzhen Binhai Avenue (Headquarters Base Section) traffic reconstruction project. Based on the actual physical and mechanical properties of the soil strata, a three-dimensional numerical model was established and validated against the load–displacement curves obtained from the in situ full-scale uplift tests. On this basis, the uplift bearing performance of squeezed branch piles, the differences in uplift bearing performance between branch and plate structures, and their applicable strata were analyzed. The plate structure and different branch configurations of squeezed branch piles exhibit distinct symmetric configuration characteristics, and these configuration differences influence the overall uplift bearing performance. The results show that the load–displacement curves of the uplift piles are generally smooth, without obvious abrupt rises or drops, exhibiting a gradual variation pattern, and the maximum pile-head displacements are all less than 100 mm. The mobilization of the bearing capacity of the branch and plate structures exhibits a distinct temporal and sequential pattern, with the plate structures at shallower embedment depths mobilized earlier than those at greater depths. Compared with conventional cast-in-place pile foundations, the presence of branches and plates endows squeezed branch piles with better elastic mechanical behavior and higher rebound ratios during unloading. Under identical stratum and loading conditions, the uplift bearing performance of the plate is 133% higher than that of the six-radial-branch configuration, while that of the six-radial-branch configuration is 34% higher than that of the four-radial-branch configuration. It is recommended to adopt the six-radial-branch configuration in clayey sandy gravel strata and the plate configuration in gravelly clayey soil and completely weathered coarse-grained granite strata, whereas neither branches nor plates are recommended in soil-like strongly weathered coarse-grained granite strata. Full article

Existing methods for assessing the stability of deep tunnel face rarely account for the weakening effect of rock mass parameters caused by excavation disturbance. This paper employs a vertical discretization method to divide the rigid failure body into vertical strip elements with fixed horizontal widths. By considering the weakening effect of rock mass parameters, a stability analysis model for the tunnel face is established. The equivalent cohesion and internal friction angle of the rock mass are obtained using the Hoek–Brown criterion and the equivalent Mohr–Coulomb transformation. Combined with the disturbance weakening factor, these yield the equivalent rock mass parameters after disturbance. Stability is solved using limit analysis and the principle of virtual power. The accuracy of the established model is verified through numerical simulation, demonstrating that the proposed analytical approach requires only about 90 s per run compared to approximately 7 h for 3D numerical models. The results indicate that the importance of parameters, in descending order under the specified reference conditions for deep-buried tunnels, is GSI > D_r > h₁ > m_i, where GSI play a dominant role. Excavation disturbance significantly reduces rock mass strength numerically. Assessing GSI and controlling the blasting disturbance are key to ensuring the stability of deep tunnels. Full article

This work presents an integrated experimental and numerical determination of the aerodynamic (lift) characteristics of an ogive forebody equipped with all moving canards. Experimental testing was conducted in the subsonic custom-made wind tunnel of the Vlatacom Institute at a nominal free stream velocity of 32 m/s (and Mach number M = 0.09). Aerodynamic loads on the canards were measured using a custom one-component force balance, while free stream flow properties were obtained via a calibrated Pitot–Prandtl probe on the full-scale geometry model. On the numerical side, RANS simulations were performed in ANSYS Fluent using the k-ω SST turbulence model. Two geometric representations were considered: (a) a high-fidelity configuration explicitly resolving the physical gap between the canard and ogive, and (b) a simplified configuration with the gap removed. Boundary conditions, Reynolds number, and operating parameters were matched to the wind tunnel conditions to enable a strict one-to-one comparison. Particular emphasis was placed on examining the effect of geometric simplification on the predicted lift characteristics. The gap-resolved configuration reproduces the experimentally measured lift curve within approximately 10% across the investigated angle-of-attack range, satisfying conventional aerodynamic validation criteria. The results confirm both the robustness of the applied RANS approach for highly three-dimensional separated flows often found in engineering applications, as well as the reliability of the experimental measurement system. Full article

Mechanical construction of metro-connected aisles is a novel construction method in the field of metro engineering, and it is being gradually applied to practical projects at present. However, current research predominantly focuses on the mechanical response of tunnel structures, with insufficient theoretical investigations into ground settlement. To study the ground settlement law caused by the mechanical construction of the metro-connected aisle, the ground settlement was divided into the superposition of settlement caused by the construction of the main shield tunnels and the connected aisle. The modified Peck formula was used to calculate the ground settlement caused by tunnel excavation. Based on the integration of the Mindlin solution, the ground settlement caused by the jacking force of the cutterhead was solved, and the three-dimensional calculation formula for ground settlement was derived. Taking the NO. 1 connected aisle of Shenzhen Metro Line 8 as the research object, the accuracy of the calculation formula was verified through comparative analysis with three-dimensional numerical simulation results and in situ monitoring data, and good agreement was observed. The research results indicate that after the construction of a connected aisle, a wedge-shaped surface appears on the settlement surface at the location of the connected aisle. The surface settlement curve presents a “U”—shaped distribution; as the depth increases, the stratum settlement curve presents a “W”—shaped distribution. The stratum disturbance caused by the connected aisle is more significant in its longitudinal direction than in the transverse direction. The theoretical calculation results show that the maximum surface settlement generated by the construction of the connected aisle is 0.61 mm, accounting for about 15.6% of the total settlement value (3.9 mm), and is far below the control value adopted by Shenzhen Metro. The calculation formula proposed in this article can be used to evaluate the surface settlement caused by the construction of connected aisles. Full article

Beyond their classical role as “cellular powerhouses”, mitochondria are increasingly recognized as dynamic and interconnected networks whose architecture, quality control, and intercellular communication influence cellular and organismal homeostasis. Mitochondrial dynamics—including fusion–fission balance, mitophagy–biogenesis coupling, intracellular organization, and intercellular transfer via tunneling nanotubes, extracellular vesicles, or transient cell fusion—contribute to tissue adaptation and functional decline during aging. Focusing on cardiac muscle, skeletal muscle, and the nervous system, this narrative review synthesizes current evidence describing how aging disrupts mitochondrial network integrity through altered dynamics, impaired organelle positioning and transport, reduced mitophagy, mtDNA instability, and compromised metabolic coupling between cells. These alterations propagate across tissues, limiting energetic flexibility, stress resilience, and regenerative capacity. Building on these mechanisms, we discuss a systems-level perspective in which aging is associated with progressive loss of mitochondrial network coherence rather than solely cumulative molecular damage. Within this framework, mitochondrial connectivity functions as an integrative descriptor of cellular resilience: well-organized networks counteract metabolic perturbations, whereas functionally decoupled networks amplify stress and promote maladaptive aging trajectories. Emerging evidence indicates that physiological and pharmacological interventions, including endurance exercise, caloric restriction or mimetics, fusion-supporting pathways, and mitophagy-enhancing strategies, can partially restore network organization even later in life. Molecular, cellular, and tissue-level insights are integrated to highlight mitochondrial network dynamics as both a mechanistic contributor to aging and a potentially modifiable target for future preventive and therapeutic interventions. Full article

Traditional pipe roof support design methods generally assume horizontal ground conditions and treat the pipe roof as a monolithic beam, thereby neglecting the differential stress distribution among individual steel pipes under unsymmetrical loading. To address this gap, this paper presents two main contributions: a low-carbon cement-based grouting material suitable for pipe roof reinforcement, and a new mechanical model that simultaneously accounts for biased pressure conditions and the inter-pipe micro-arch effect. First, the working performance of limestone calcined clay cement (LC³) grout was systematically tested at a water–cement ratio of 1:1, and the optimal mix ratio was determined. Grout–soil reinforcement tests on weathered granite show that, for grout-to-soil volume ratios between 0.2 and 0.8, the compressive strength of the reinforced material exceeds 10 MPa and the elastic modulus exceeds 600 MPa. Second, a mechanical model for the pipe roof was established based on the Pasternak two-parameter foundation theory, incorporating both biased pressure conditions and the inter-pipe micro-arch effect. The model predictions were compared with existing field monitoring data in the literature, showing consistent trends and good agreement in peak deflection values. Parametric analysis reveals that under horizontal ground conditions, the pipe roof response is symmetric, with the vault as the most critical area. As the bias angle increases, the maximum response shifts toward the higher side of the terrain, and the stress difference between pipes on both sides increases significantly. Theoretical analysis of the low-carbon grouting material shows that pipe roof deflection is moderately reduced compared to traditional grouting materials, but at the cost of increasing bending moment and shear force within the steel pipes. The proposed low-carbon grouting material and the validated mechanical model provide theoretical support for the design optimization of pipe roof support in shallow unsymmetrical loading tunnels. Full article

Due to its strong near-infrared (NIR) absorption and high thermal conductivity, graphene is considered an excellent nanophotothermal filler that can effectively improve the photothermal conversion performance of composites. In particular, graphene–polymer nanocomposites, new types of photothermal conversion materials, have broad application prospects in photothermal therapy, photothermal driving, and micro-/nanomachinery. Recent research results have shown that when the filling concentration of graphene nanosheets (GNSs) in the matrix reaches the percolation threshold, interface effects such as interface tunneling and Maxwell–Wagner–Sillars (MWS) polarization, the key factors affecting the photothermal conversion performance of such composites, will occur. Furthermore, graphene exhibits unique optical conductivity due to its strong interaction with light. To reveal how interface effects influence the photothermal conversion performance of these nanocomposites, the optical conductivity of graphene at near-infrared frequencies was introduced to modify the effective medium theory. By combining this with a photothermal conversion model, the photothermal conversion behaviors of GNS–polymer composites are discussed, taking into account the interface effects and optical conductivity characteristics of GNSs. Full article

Traditional road tunnel ventilation systems suffer from high energy consumption and limited effectiveness in fire smoke control. Thus, there is a pressing need to develop advanced air purification technologies that integrate low energy demand with efficient smoke mitigation capabilities. In this study, a self-developed negative ion purification system was implemented, and systematic full-scale experimental investigations were conducted in both a test tunnel and an operational road tunnel to evaluate its performance in air purification and smoke suppression under normal operation and fire conditions. Key parameters, including negative ion concentration, particulate matter concentration, carbon monoxide (CO) concentration, and smoke distribution characteristics, were measured to elucidate smoke evolution behavior and the underlying mechanisms influenced by negative ions. The results show that the negative ion purification system can rapidly establish a high-concentration negative ion field within the tunnel space. Under normal operating conditions, negative ions markedly reduce particulate matter concentrations and their fluctuations, thereby effectively improving tunnel air quality. Under fire conditions, the system maintains high purification efficiency, with significant reductions in particulate matter concentration observed in the test tunnel and clear suppression of longitudinal particulate transport in the real tunnel. In particular, PM10 exhibits a higher removal efficiency. In addition, negative ions promote particle agglomeration and gravitational settling, accelerate CO dilution and dispersion, and significantly improve tunnel visibility. The results demonstrate that the negative ion purification system exhibits strong applicability and considerable engineering potential across different spatial scales and fire scenarios. Full article

Large-section tunnels produce a large amount of dust after drill-and-blast construction. If not removed in a timely manner, the dust will seriously endanger workers’ health. For the purpose of enhancing the working conditions within the tunnel during construction, this investigation employs an integrated methodology that combines computational simulations with on-site measurements. Drawing upon the principles of gas–solid two-phase flow theory, the coupled diffusion law of airflow and dust in large-section tunnels is investigated. A two-factor orthogonal experiment combined with economic analysis is employed to determine the optimal ventilation parameters for the forced ventilation system. The findings indicate that, when the initial ventilation configuration is applied, the airflow field is divided into three stages, and dust diffusion is primarily driven by airflow. The average dust concentration in the 1.6 m breathing zone at 600 s post-blasting is measured to be 36.8 mg/m³. While satisfying the ventilation demand stipulated for the tunnel, the optimal ventilation parameters are determined as an outlet air velocity of 18 m/s and a duct-to-face distance of 40 m. Under these conditions, the dust concentration is reduced to 1.5 mg/m³, representing a 95.9% improvement in dust removal efficiency. Additionally, the hourly electricity cost at 18 m/s is USD 4.39 lower than that at 20 m/s. This study provides valuable insights for optimizing forced ventilation parameters in large-section tunnels, significantly reducing pollutant levels while saving costs. Full article

Transonic buffet is a critical self-sustained shock/boundary-layer instability limiting the flight envelope of modern transport aircraft. This study investigates the interaction between shock buffet and forced wing motion on the Airbus XRF-1 wind tunnel model, using unsteady Reynolds-Averaged Navier–Stokes (URANS) simulations with the DLR TAU code. The investigation is carried out in deep buffet condition ($\mathrm{Ma}=0.84$, $\alpha =4.5^{\circ }$, $\mathrm{Re}=25\times {10}^6$) and validated against wind tunnel data at the same flow condition. The buffet flow is superimposed with forced wing motions derived from a symmetric wing eigenmode at $\mathrm{Sr}=0.164$. Two different amplitudes scaled with the half-span s are considered: $A_{tip}=0.0025·s$ and $0.01·s$. The baseline no-forcing URANS captures the buffet flow quite well with only small deviations in the standard deviation of the surface pressure coefficient $c_{p,rms}$. A special variant of the Discrete Fourier Transformation for the whole wing upper surface $c_p$ distribution revealed that the typical buffet frequencies are also matched. The analysis of the forced simulations revealed a strong influence of the local wing motion on the increase of $c_{p,rms}$. The spectral content showed a shift and damping or amplification of different buffet modes, which is relevant for the interaction of motion induced and buffed induced aerodynamic forces. Full article

This paper investigates the influence of three key parameters, which are the spacing of cutters, the dip angle of joints and the spacing of joints on the load evolution process of jointed rock masses from the perspective of rock-breaking mechanics. Furthermore, how variations in cutter spacing and joint characteristics affect cutting efficiency is studied from a macroscopic viewpoint, focusing on indicators such as specific energy (SE) for crack propagation and rock fragment formation. Based on the research results, a novel optimization approach for cutter spacing in jointed rock mass conditions is proposed. The optimal cutter spacings under varying joint conditions are calculated, and the effects of joint spacing and dip angle on cutter spacing optimization are systematically discussed. The results show that when the joint dip angle is 60°, the cutter spacing is 100 mm, and the joint spacing is 30 mm, the rock fragmentation efficiency reaches the highest. It is also found that the influence of the joint dip angle on the optimal cutter spacing is greater than that of the joint spacing. When the joint spacing is 70 mm, the corresponding optimal cutter spacing is 100.7 mm. When the joint dip angle increases from 0° to 60°, the optimal cutter spacing gradually increases to 112.8 mm. When the joint spacing is greater than 60 mm, the optimal hammer spacing of the hammer gradually decreases. Full article

Magnetically driven microrobots operating in intestinal environments face two major challenges: difficulty in traversing low-height confined spaces and limited local visibility caused by mucosal obstruction. To address these issues, this study proposes a gradient-field-based force-driven control method for a mudskipper-inspired magnetic microrobot. By establishing the mapping among coil current, magnetic field, and magnetic force at the robot working point, and by solving the control input through singular value decomposition and linear programming, effective magnetic-force output along a desired direction was achieved. On this basis, two representative force-driven motions were designed. The first was a translational mode based on pulsed magnetic-force actuation for stable navigation in low-height confined spaces. The second was a lifting mode based on continuous loading and gradual adjustment of the magnetic-force upper bound to locally lift a flexible “mucosa-like” membrane, thereby simulating intestinal mucosal elevation and local visual field expansion. Experimental results showed that the robot could stably pass through narrow tunnels and effectively lift an overlying flexible membrane under vertical magnetic-force actuation. The proposed method extends both the locomotion capability and the local interaction capability of the mudskipper-inspired magnetic microrobot, and demonstrates a feasible proof-of-concept approach for confined-space navigation and localized manipulation in intestinal applications. Full article

To evaluate the coupled deformation of existing shield tunnels induced by multi-segment excavations with isolation piles, this study develops an integrated analytical framework combining a Kerr three-parameter foundation-plate model with a three-dimensional image-source solution. A closed-form expression for the soil displacement field is first derived by incorporating layered soil conditions, staged excavation, and associated spatial effects. The soil–pile interaction of isolation piles is then modeled using the Kerr foundation, and the flexural response is obtained through variational formulation and finite-difference discretization. These responses are sequentially propagated through the excavation stages, enabling the superposition of multi-pit effects on the final retaining-wall deformation. The image-source method and a volume-equivalent transformation are further used to convert wall deformation into an additional stress field acting on the tunnel, which is ultimately coupled with a tunnel–soil deformation–coordination model to compute horizontal tunnel displacements. This unified workflow establishes a continuous mechanical transfer chain—from excavation-induced soil loss to isolation-pile bending and finally tunnel deformation. Parametric analyses show that lateral displacement of the retaining structure is jointly governed by wall bending and pit-bottom uplift, producing a right-skewed “S-shaped’’ profile. The bending-moment peak shifts toward earlier-excavated zones, indicating a memory effect of excavation sequencing. Two engineering cases verify that the proposed method accurately reproduces the magnitude and depth of measured wall deflections, while predicted tunnel displacements show a near-Gaussian pattern with high accuracy near the peak. The analytical framework provides a robust theoretical basis for optimizing pit segmentation and excavation sequencing adjacent to shield tunnels. Full article

Background: The plantaris muscle (PM) shows substantial variability in its proximal belly attachments. Although often deemed vestigial, specific variants may narrow or reshape the popliteal corridor and contribute to vascular (popliteal artery entrapment syndromes, PAES) and neural conflict (TN, CPN, sural nerves). Despite abundant anatomical descriptions of the plantaris, its contribution to neurovascular compression has not been organised into a classification-linked, imaging-integrated framework. Objective: To synthesise adult and foetal anatomical data with clinical–radiological evidence into a classification-linked framework that stratifies vascular and neural compression risk by proximal PM variants, and to propose an integrated risk matrix and variant-directed diagnostic/operative pathway. Methods: Narrative, classification-centred review centred on the Olewnik schema (Types I–VI) and multi-headed/accessory variants. We mapped variant geometry to (1) physiological compromise on provoked Doppler US and (2) anatomical correlates on MRI/MR angiography (MRA) (axial “band sign”), deriving graded risk for vascular and neural axes and an integrated, action-oriented grade per limb. Results: Baseline risk is low for canonical/compact footprints (Type I–IA, Type V), moderate for capsular-junction patterns (Types II/III), and potentially higher-risk for lateral linkage (Type IV; iliotibial band (ITB)/Kaplan fibres continuity) and multi-headed configurations (duplication, bifurcation, ≥3–4 heads; accessory proximal slips). The integrated matrix upgrades risk for a clear band sign, reproducible compromise on provoked Doppler US, or multi-headed/Type IV anatomy and downgrades when rigorous provocation is negative and muscle volume is small. We provide a variant-indexed imaging checklist, common pitfalls (e.g., Type IV misread as ITB thickening; multi-headed variants misread as cyst/tumour), and operative checkpoints to target capsular clefts, lateral bands, tunnels, and accessory slips. Conclusions: A classification-linked, imaging-integrated approach clarifies which proximal PM variants are plausibly associated with neurovascular entrapment (based on case-level evidence) and aligns work-up with targeted decompression and may improve diagnostic precision and inform surgical planning. Clinical relevance: The framework operationalises variant naming in reports, standardises dynamic provocation and axial mapping, and prioritises variants considered higher risk (Type IV; multi-headed) for early multidisciplinary review. Given that most clinical signals derive from case reports/series (Level IV), these recommendations are inferential and should be applied with clinical judgement. Full article

Impact artificial seismic sources are gaining popularity in reflection seismic exploration. However, challenges arise due to the uncertain delay between the hammer’s acceleration and its impact on the interface, as well as the strong vibrations or pulsed magnetic fields produced during the acceleration process. These factors complicate the synchronous triggering methods typically used in traditional explosive and sledgehammer artificial seismic sources, often resulting in temporal misalignment of the acquired data. To tackle this issue, this study introduces a high-precision synchronous triggering method based on non-contact audio detection. Utilizing an STM32F4 microcontroller as the core hardware, the system collects ambient audio and extracts 39-dimensional acoustic features via Mel-frequency cepstrum coefficients (MFCC). A lightweight convolutional neural network (CNN) model is employed to accurately identify hammer impact events. Additionally, a synchronization time compensation mechanism is implemented to address system processing delays. Results from 300 field tests conducted in three environments—open ground, construction site, and mining tunnel—demonstrate that the system achieves a triggering accuracy of up to 94.6%, with compensated triggering time errors controlled within ±125 μs, thereby meeting the minimum tolerable synchronous triggering error requirement. This study significantly enhances the reliability of impact-type Artificial Seismic Source exploration data and offers insights for the application of sound recognition in engineering surveying and other related fields. Full article