Search Results (2,814)

This paper addresses the chromatic aberration and off-axis collimation issues in the laser–lens–fiber coupling system by proposing a chromatic aberration-corrected Meta-lens design based on a particle swarm optimization algorithm and structural interleaving method. By establishing an optimization model that includes wavelength-dependent phase factors, achromatic performance with a focal length standard deviation of less than 0.4 μm is achieved in the 1260–1360 nm band. Innovatively, the structural interleaving technique is adopted to integrate multiple different phase distributions into a single meta-surface, keeping the coupling efficiency fluctuation within 8% over a ±1 μm off-axis displacement range. The research results demonstrate that this method effectively solves the phase quantization and dispersion matching challenges of large-scale meta-lens, achieving a phase matching efficiency of 95.2%, providing a feasible path for the engineering application of highly robust meta-lens in high-precision optical systems. Full article

Geosynthetics-reinforced soil technology represents an innovative reinforcement method for calcareous sand foundations and revetment engineering in coral reef areas. The interaction response at the reinforced soil interface directly influences the safety and stability of reinforced soil structures. However, research on the interaction mechanisms between geosynthetics and calcareous sand interfaces remains insufficient. Therefore, this paper investigates the effects of different normal stresses and various interface types on the shear characteristics of the geosynthetics–calcareous sand interface through a series of large-scale monotonic direct shear tests. By integrating statistical damage theory and accounting for the influence of residual strength, we establish the constitutive relation for interface damage. The results indicate that the shear stress–displacement curves for both the geosynthetics–calcareous sand interface and the unreinforced calcareous sand exhibit softening behavior. Furthermore, the relationship between the interface shear modulus and horizontal displacement for the geogrid–calcareous sand and unreinforced calcareous sand adheres to a power function model, while the relationship for the geotextile–calcareous sand follows a logarithmic function model. In the structural design of geosynthetics-reinforced calcareous sand, it is crucial to consider the influence of residual shear strength on structural stability. This study proposes a statistical damage constitutive model that accounts for the strain-softening characteristics of the geosynthetics–calcareous sand interface, while also considering the impact of residual strength. The findings provide a theoretical basis for the stability analysis of geosynthetics-reinforced calcareous sand structures in coral reefs with significant engineering implications for island reef construction, coastal development, and bank slope protection projects. Full article

This study tested quarter-scale adobe masonry walls under monotonic in-plane loading, considering the effect of water content at the foundation–wall interface, fiber type, and openings (i.e., door, window). Seven walls were constructed with unstabilized adobe bricks containing either cut straw or sisal fibers and mud mortar. Gravimetric water content (w_b) at the foundation–wall interface (i.e., wall base) varied by test wall, ranging from 2.4 to 4.9% by dry mass. The walls were instrumented to measure in-plane and out-of-plane displacements and vertical deflections during the load tests. Greater water contents at and near the wall base shifted cracking toward the lower courses and along the foundation–wall interface; however, the peak load capacity did not vary significantly with w_b but was strongly influenced by crack trajectory, including whether cracking diverted into the foundation or propagated rapidly along the foundation–wall interface. Peak loads ranged from 1928 N (433 lb) to 6517 N (1465 lb). Fiber type influenced deformation behavior of the walls, with sisal-brick walls generally developing larger vertical deflections and, in some instances, larger peak in-plane displacements than straw-brick walls. Window and door openings altered crack initiation and propagation by concentrating cracking at opening corners and producing segmented mechanisms, increasing in-plane displacements in some cases, but still sustaining comparatively large peak loads. Full article

The Ordos Basin hosts abundant lacustrine shale oil resources. Adequately retained hydrocarbons in source rocks, together with favorable mobility, are prerequisites for large-scale shale oil exploitation. Therefore, the quantitative characterization of retained hydrocarbon content and mobility is a core research focus in shale oil exploration and development. This study investigates Chang 7 shale with varying lithofacies and geochemical characteristics. Stepwise pyrolysis and pyrolysis gas chromatography–mass spectrometry (GC–MS) were applied to analyze retained hydrocarbons in different occurrence states, their compositions, and biomarkers. In addition, nuclear magnetic resonance (NMR) combined with CO₂ flooding experiments was conducted, and the collected products under different displacement pressures were analyzed using GC–MS. The aim was to quantitatively examine the variations in expelled oil volume, compositional differences during migration, and occurrence features of shale oil within reservoir micro-pores. The results show the following: (1) Organic-rich shale is characterized by higher proportions of light and medium hydrocarbons, lower heavy fractions, and elevated aromatic hydrocarbon content. In contrast, low-organic-carbon mudstone or siltstone contains more medium and heavy hydrocarbons, with lower light and aromatic fractions. The C13−/C14+ ratio increases with total organic carbon (TOC). (2) In black shale, oil displacement is mainly contributed by mesopores. At low pressures, oil expulsion is difficult and dominated by heavy hydrocarbons. When pressure reaches a threshold, the capillary-bound oil in micropores is released, increasing production and improving oil quality. Muddy siltstone shows higher displacement efficiency than black shale, with contributions from pores of all sizes. At low pressures, its expelled oil volume is larger and lighter than that of black shale. With increasing pressure, the oil yield rises significantly, and medium–large pores produce heavier fractions compared with micropores, likely because light hydrocarbons preferentially enter micropores and are less prone to dissipation. (3) The main controlling factors for shale oil enrichment include retained hydrocarbon content, mobile hydrocarbon fraction, fluidity, and engineering-related parameters. Thick shale layers with high organic matter abundance, high proportions of light–medium hydrocarbons, and favorable porosity–permeability conditions, as well as interbedded siltstone, are enriched in mobile hydrocarbons. Full article

Accurate prediction of the dynamic load-bearing characteristics of suction anchors is critical for the safety and reliability of floating offshore wind turbines. This study bridges the gap between mooring approaches and anchor foundation response assessment by systematically quantifying how the choice of mooring analysis method (dynamic or quasi-static) affects the predicted displacement response of suction anchors. Using OpenFAST coupled with a validated suction anchor dynamic response model (SADR), the motion responses of the suction anchor foundation for the OC4 semi-submersible platform are computed under regular waves of varying heights and periods, as well as irregular sea states representing operational and extreme conditions. The results reveal that the ratio of the anchor displacement predicted by dynamic mooring analysis to that predicted by quasi-static mooring analysis grows nonlinearly with increasing wave height and rises substantially as wave period lengthens, indicating that mooring dynamic effects become progressively more pronounced under large wave heights and long-period swell conditions. Statistical analysis under irregular waves further reveals that under moderate operational conditions, the response variability predicted by the two methods remains comparable; however, under extreme sea states, dynamic analysis yields not only larger peak displacements but also substantially greater response variability, with standard deviations significantly exceeding those obtained from quasi-static predictions. These findings provide quantitative evidence that the application of quasi-static mooring analysis to anchor foundation design carries a substantial risk of underestimating true responses, and that this underestimation becomes increasingly severe under high wave heights, long periods, and extreme conditions. The work establishes that dynamic mooring analysis is essential for reliable suction anchor foundations design and long-term serviceability assessment. Full article

Human–elephant conflict (HEC) has emerged as a major conservation and socio-economic challenge across Asia, largely driven by habitat degradation and increasing human pressure within elephant ranges. In India, expanding agriculture, mining activities, and infrastructure development have progressively altered forest landscapes, restricting elephant movement and intensifying interactions with human settlements. This study examines the relationship between landscape dynamics and HEC in the West Singhbhum district, Jharkhand, India. A three-year field investigation (2018–2020) across four forest divisions—Porahat, Chaibasa, Kolhan, and Saranda—was integrated with multi-temporal land-use and land-cover (LULC) analysis from 2000 to 2020 to evaluate habitat changes and their influence on conflict patterns. During the study period, 157 human casualties and extensive crop and property losses were recorded, indicating the severity of the conflict in the region. Landscape analysis revealed a substantial decline in dense forest cover and a reduction of large core forest areas (>500 acres), accompanied by increasing agricultural expansion and forest perforation. NDVI trends further indicated widespread deterioration in vegetation condition, reflecting declining habitat quality. These structural landscape changes have fragmented elephant habitats and displaced movement routes toward human-dominated landscapes and are thus associated with a spatial clustering of conflict events, particularly in the Chaibasa Forest Division. In contrast, the Saranda Forest Division retains relatively intact forest cores and supports more stable elephant habitat conditions. The findings demonstrate that HEC in the region is strongly linked to habitat fragmentation and declining vegetation quality rather than random elephant behaviour. Maintaining large contiguous forest blocks, restoring landscape connectivity, and implementing targeted mitigation strategies are therefore essential for sustaining elephant populations while reducing conflict with local communities. Full article

In this study, the sintering behavior and electrical properties of 0.7Pb(Zr_0.46Ti_0.54)O₃ (PZT)–0.1Pb(Zn₁/₃Nb₂/₃)O₃ (PZN)–0.2Pb(Ni₁/₃Nb₂/₃)O₃ (PNN) piezoelectric ceramics with different Pb(Fe₂/₃W₁/₃)O₃ (PFW) doping contents were investigated to obtain a formulation that can be co-fired with silver (Ag) electrodes below 900 °C for multilayer ceramics. PFW was introduced as a sintering aid, which effectively reduced the sintering temperature of the ceramics from 1200 °C to 850 °C. The sample with x = 0.12 exhibited the largest average grain size of 1.72 μm, achieving excellent comprehensive properties with piezoelectric constant (d₃₃) = 477 pC/N, planar electromechanical coupling factor (k_p) = 0.68, dielectric loss tangent (tanδ) = 0.0154, and relative density of 98.2%. Furthermore, the feasibility of fabricating piezoelectric actuators based on this optimized composition was verified. Multilayer piezoelectric devices were prepared via screen printing combined with a carbon-based sacrificial layer method. No obvious interdiffusion was observed at the interface between the Ag internal electrodes and the ceramic matrix. The 9-layer device attained a high d₃₃ = 1470 pC/N and produced a large displacement of 5.5 μm (corresponding to a strain = 1.83%) with a voltage of 500 V. The thickness of the multilayer piezoelectric film was approximately 0.3 mm. Through this, the feasibility of manufacturing a multilayered actuator with an Ag electrode was confirmed through the composition of 0.58PZT–0.1PZN–0.2PNN–0.12PFW. Full article

Excavation and dewatering are the primary factors governing diaphragm wall deformation and ground surface settlement in deep foundation pits. However, their coupled effects in soft-over-hard composite strata remain insufficiently understood. This study investigates a deep metro foundation pit in Jinan, China, and develops a three-dimensional hydro-mechanical coupled model in ABAQUS to simulate the complete staged excavation and dewatering process. The evolution of diaphragm wall lateral displacement, ground surface settlement, and pore-water pressure was systematically analyzed, and the simulation results were validated against field monitoring data. The results show that both excavation and dewatering induced significant wall deformation and surface settlement, with excavation playing the dominant role. The incremental lateral displacement of the diaphragm wall caused by excavation was approximately 2.6–3.8 times that caused by dewatering, while the corresponding ground surface settlement was 7.9–10.7 times greater. Owing to the strong restraint provided by the underlying rock stratum, the maximum lateral displacement of the diaphragm wall occurred at approximately 0.67 H_e, where H_e is the final excavation depth. The primary influence zone of ground surface settlement extended to approximately 2 H_e. In addition, dewatering altered the seepage field inside and outside the pit, leading to a continuous decrease in pore-water pressure within the pit, whereas the external pore-water pressure remained largely unchanged because of the seepage-barrier effect of the diaphragm wall. These findings provide practical guidance for the design and construction of deep foundation pits under similar geological conditions. Full article

Relying on the Dujiangyan Irrigation Project, the Siguniang Mountain Rail Transit project, and the Balang Mountain No.1 Large Longitudinal Slope Tunnel Project, this paper systematically studies the mechanical response of the surrounding rock and support structure induced by TBM tunneling in composite stratum by using the methods of indoor test, similar model test and numerical simulation. In model tests with different rock dip angles (0°, 10°, 20°, 30°), the main findings are as follows: (1) The maximum settlement of the arch crown reaches −4.89 mm (monitoring surface 2, 20° dip angle), the displacement of the arch waist is smaller than that of the arch crown, and the deformation of the soft rock section is more significant. (2) The peak radial surrounding rock pressure generally occurs at a distance of 5 cm from the tunnel wall, with the highest pressure in the soft rock area of the arch waist reaching 16.807 kPa (monitoring surface 4). (3) The lining stress increases with the increase in rock dip angle, and the stress distribution on the same monitoring surface shows as arch waist > arch crown > arch shoulder, with the maximum stress concentrated in the soft rock area of the arch waist. Then, the finite difference method is used for numerical simulation to analyze the convergence deformation mechanism in the composite formation. The results indicate a strong consistency between the simulated displacement/stress patterns of the surrounding rock and lining structure and the experimental data. The research results provide a theoretical basis and experimental reference for the design and construction of similar projects. Full article

Public health suffers from noxious gas emitted by massive beached Sargassum algae. Net-barrages deployed in near-shore seas can contain Sargassum, provided they efficiently resist the additional hydrodynamic pressure induced by the catch. Nowadays, the design and installation of net-barrages are empiric. Structural breaks and anchor and mooring chain drifts can arise. We provide a mechanical model to evaluate stresses and loads on a structure made of fishing nets and buoy moorings. Hydrodynamic uncertainties occur through catches, fouling and sea current amplitudes appearing in lagoons or sheltered bays. This study presents a non-linear four-node finite-element model for continuous elastic membranes undergoing large displacements and small strains. The model relies on the Lagrangian linearly elastic membrane theory, employing the non-linear Green strain tensor and a non-updated hydrodynamic loading. We study forcings fixed a priori on a netting section of barrage that is 50 m long and 1 m high with double layer, e.g., two net-faces. We consider low and moderate current velocities, 0.05 and 0.35 m∙s⁻¹, while assuming specific vertical and horizontal catch pressures. A barrage installed in the reef lagoon at Le François on Martinique Island that is observable by satellite imagery could benefit of the computed net and mooring tensions. Full article

Background: The risk stratification of unruptured intracranial aneurysms (UIAs) relies largely on static clinical and morphological parameters, which may not fully capture aneurysm-specific wall behavior. ECG-gated four-dimensional computed tomography angiography (4D-CTA) enables the time-resolved assessment of aneurysm wall motion, but reliable interpretation requires the differentiation of biological motion from measurement uncertainty. Methods: In this prospective exploratory pilot study, ECG-gated 4D-CTA was used to evaluate the longitudinal aneurysm size change, global volumetric pulsation (GVP), spatial wall pulsation (SWP), intrinsic wall deformability and variability. Size change and pulsation were defined using predefined resolution- and noise-based thresholds. Spatial wall motion was assessed using phase-resolved three-dimensional displacement maps. Harmonic modeling isolated periodic pulsation, and residual variability exceeding empirically derived uncertainty limits was conservatively interpreted as deformability. Associations with aneurysm growth and ELAPSS scores were analyzed using exploratory statistics. Results: Eleven UIAs in ten patients were followed for 4.3 ± 1.1 years. A longitudinal size change occurred in six aneurysms (54.5%). Baseline GVP was present in eight aneurysms (73%) and SWP in nine (82%). GVP was not associated with a size change (p = 1.00). All aneurysms with a size change exhibited baseline SWP, whereas no size change was observed in aneurysms without SWP; however, this association did not reach statistical significance in this small exploratory cohort (p = 0.18). Conservative variability metrics were not associated with growth but correlated with baseline shape irregularity, particularly the undulation index (Spearman’s ρ up to ~0.90). Conclusions: In this small exploratory pilot cohort, spatial wall pulsation showed a descriptive directional pattern with longitudinal aneurysm size changes, whereas global volumetric pulsation did not. These findings are preliminary, should be interpreted cautiously, and require confirmation in larger, adequately powered longitudinal studies before clinical application. Full article

In designing tall buildings, the primary concern is ensuring an effective lateral load-resisting system in addition to the gravity load system, since it largely governs the overall design. This study investigates the influence of X-cable bracing on the structural weight of tall steel frame buildings subjected to service and wind loading. Three numerical case studies, 10-story, 20-story, and 30-story planar steel frames, were modeled and analyzed using SAP2000, then optimized using Differential Evolution (DE) and Enhanced Colliding Bodies Optimization (ECBO) algorithms. These designs were evaluated under both service and wind load conditions, considering strength and drift constraints. The results indicate that the inclusion of wind loads in addition to service loads leads to a higher total structural weight than considering service loads alone, while cable bracing effectively reduces the overall mass by up to 6%, 38%, and 20% for the 10-story, 20-story, and 30-story frames, respectively, compared to unbraced structures, by improving the internal force distribution among structural components. Strength demands, reflected by the interaction ratio, governed all design cases, while lateral displacement was always less than the maximum limit according to AISC and ASCE requirements. Overall, the results highlight the potential of cable bracing systems to deliver efficient tall building designs; however, further studies are needed to generalize these findings to a broader range of building configurations. Full article

With the large-scale construction of coastal high-speed railways, understanding the mechanical behavior of high-speed railway box girders under tsunami waves has become increasingly important. Existing studies on tsunami-induced forces on bridge girders have mainly focused on T-girders and plate-girders in highway bridges. In contrast, research on high-speed railway box girders, which are characterized by a significant height-to-width ratio, large cantilevers, and complex ancillary facilities on the girder top, remains relatively scarce, especially regarding its behavior under tsunami waves and the effects of lateral displacement on its dynamic response. In light of this, this study focuses on the investigation of the mechanical behavior of a single-track high-speed railway box girder under tsunami waves, and fifth-order solitary waves and dam-break waves are comparatively employed to simulate the typical unbroken and broken tsunami waves. The interaction between tsunami waves and the fixed railway box girder is numerically conducted, and the characteristics of the interaction process and the variation in maximum forces with girder clearance are thoroughly investigated. After that, the numerical interaction between tsunami waves and the laterally movable railway box girder is comparatively carried out, and the lateral displacement effects on the girder wave forces are exhaustively investigated. The results indicate that unbroken and broken tsunami waves exhibit distinctly different interaction processes with the box girder. With decreasing girder clearance, for the unbroken wave, the maximum horizontal and vertical forces occur when the girder bottom and the cantilever root descend to the initial water surface, respectively; for the broken wave, the horizontal and vertical forces simultaneously occur when the girder bottom nears the water surface with a small clearance. Lateral displacement can reduce wave forces on the girder, but the reduction is quite limited—remaining below 10% at the reference stiffness of an actual bearing. It validates that using a fixed girder model to estimate wave forces on an actual laterally movable girder is a slightly conservative and reasonable approach. This study provides further insight into wave forces acting on coastal high-speed railway box girders in tsunami-prone areas. Full article

Background: Perineural catheter migration is a clinically relevant cause of continuous block failure, but the present study was not designed to model true clinical displacement. Instead, we investigated whether low-rate infusion pressure differs between two predefined catheter–tissue environments, interfascial and intramuscular, under controlled ex vivo conditions. Methods: Sixty porcine thigh specimens were studied. Under ultrasound guidance, a catheter-over-needle system with a multi-orifice catheter was placed either in the interfascial plane or intramuscularly, with one measurement obtained from each specimen. After baseline recording outside the tissue, saline was infused at 5 mL/h for 10 min. Pressure recordings were normalized to baseline. For each trace, a representative value was obtained using a predefined automated stable-segment algorithm, and between-group differences were assessed using Welch’s t-test. Results: Mean normalized pressure was higher during intramuscular than interfascial infusion (0.3346 ± 0.0635 PSI [17.3 ± 3.3 mmHg] vs. 0.1917 ± 0.0285 PSI [9.9 ± 1.5 mmHg]). The between-group difference was significant (mean difference: 0.1430 PSI [7.4 mmHg], 95% CI: 0.1181 to 0.1679 PSI; p = 7.22 × 10⁻¹⁵), with a very large standardized effect size (Hedges’ g = 2.87), reflecting strong statistical separation between the two predefined groups under controlled ex vivo conditions rather than clinical discriminative ability. However, the absolute pressure difference remained small. Conclusions: Under controlled ex vivo conditions, mean normalized infusion pressure differed between predefined interfascial and intramuscular catheter positions. However, the absolute difference was small. This binary model does not represent real catheter displacement, and the findings do not support current clinical applicability, individual-level interpretation, or the definition of a clinically usable threshold. The results should be considered exploratory and hypothesis-generating. Full article

To investigate the influence of ambient temperature variations on the natural vibration characteristics and seismic responses of suspen-dome structures, a 1:20 geometric similarity dynamic scale model was designed using the symmetric suspen-dome roof of the Lanzhou Olympic Sports Center Gymnasium as the prototype. First, white noise excitation tests and seismic simulation tests were performed on the model, and the indoor ambient temperature was measured simultaneously. Subsequently, a corresponding numerical scaled model was developed using the ABAQUS 2024 finite element software, and its temperature was set according to the shaking table test measurements. Modal analysis and seismic time–history analysis were then performed, and the model’s natural frequencies and seismic responses (such as acceleration, displacement, and internal force) were compared with the shaking table test results, thereby validating the accuracy of the numerical model and confirming that the modeling approach reliably reproduces the natural frequencies and seismic responses measured in the tests. Finally, the ambient temperature of the numerical model was set according to the historical temperature data for Lanzhou. A comparative analysis was performed to examine the variations in the natural vibration characteristics and seismic responses of the suspen-dome structure under different temperature conditions. The result shows that, as the ambient temperature increases from −30 °C to 60 °C, the natural frequencies of the suspen-dome structure decrease by up to 21.8% (e.g., the third-order frequency drops from 9.423 Hz to 7.734 Hz), with low-order natural frequencies being the most significantly affected. Furthermore, under both unidirectional and three-dimensional earthquake excitations, the peak seismic responses increase markedly: acceleration increases by up to 35.5%, displacement increases by up to 88.3%, and internal force in critical members increases by up to 68.9%. Notably, structural members experiencing higher internal force responses demonstrate greater sensitivity to ambient temperature changes. These findings indicate that ambient temperature variation significantly reduces structural stiffness and amplifies seismic responses, providing a valuable reference for the seismic performance evaluation and safety design of suspen-dome structures in regions with large annual temperature fluctuations. Full article