Search Results (416)

Reinforced concrete frame structures (RCFSs) subjected to strong seismic excitation may enter a metastable semi-ruin state before global collapse, characterized by severe local damage, degraded stability, and high secondary collapse risk. However, systematic experimental investigations and quantitative identification techniques for this critical transitional state are still lacking in existing seismic engineering literature, forming a notable research gap for post-earthquake safety evaluation. To investigate this critical transition, a Digital Image Correlation (DIC)-assisted shaking table test was conducted on a 1/25-scale RCFS specimen derived from an earthquake-damaged exterior-corridor teaching building, using the Wolong ground motion recorded during the 2008 Wenchuan earthquake as input. DIC was employed to track the full-field evolution of cracking, through-crack development, and concrete cover spalling under incremental seismic loading. Four local damage indices—crack line density (CLD), crack propagation rate (CPR), through-crack ratio (TCR), and concrete spalling ratio (CSR)—were extracted and evaluated with the inter-story drift ratio (IDR) to quantify local-to-global degradation. The results show that visible cracks initiated at PGA = 0.3 g, while accelerated crack propagation occurred at 0.7–0.8 g, with CPR peaks of 1187.5 and 1140 mm/g, respectively. At 0.5–1.0 g, the crack number increased from 13 to 26, total crack length reached 0.443 m, CLD increased to 3.9 × 10⁻⁴, and TCR reached 37.04%. At 1.1–1.5 g, crack development approached saturation, with total crack length of 0.552 m, maximum TCR of 63.6%, and CLD of 4.8 × 10⁻⁴. Under ultimate excitation of 1.6–1.8 g, the crack number stabilized at 33–34, TCR remained around 63%, cumulative spalling area reached 1026 mm², CSR reached 0.015, and the third-floor IDR approached the 1/50 elastoplastic limit. Severe through-cracking, reinforcement exposure, concrete spalling, and residual inclination indicated the onset of the semi-ruin state. The proposed multi-index framework provides quantitative support for semi-ruin-state identification and post-earthquake secondary collapse risk assessment of RCFSs. Full article

Road traffic injuries remain a central challenge for sustainable transport, public health, and mobility governance. The task of monitoring these injuries requires indicators that jointly capture harm severity, road and environmental context, and patterns of vehicle involvement at scale. Using harmonised English-language Romanian police crash exports (2023–2025), we build 92,790 records with 36 variables and estimate two complementary k-means typologies: a severity partition based on the fatality, injury, and vehicle-count fields (a register proxy for involvement, not vehicle-type attributes) and a context partition based on the road, environment, mechanism, and cause fields with one-hot encoding and TruncatedSVD. Reported tables and figures reproduce the archived MiniBatch pipeline for replication; for context, full-batch k-means clustering on the same embedding is the recommended default when cross-year prevalence stability is required (train–test TVD 0.039 versus 0.569 under MiniBatch). We report silhouette-guided choices ($k=6$ severity, $k=4$ context), cross-seed stability, feature ablations, and a 2023–2024 versus 2025 prevalence comparison. A Pearson ${\chi }^2$ test on severity × context labels reveals strong statistical significance, yet Cramér’s V remains small—statistical association with limited practical coupling, consistent with complementary rather than redundant partitions. Limitations include police-reported injury counts; a coarse vehicle proxy; weak context geometry; and large MiniBatch context drift, which binds inference to within-year descriptive profiling unless analysts refit the model, add version labels, or adopt full-batch context clustering. The contribution is an integrated, reproducible profiling and governance workflow for dashboards and follow-on modelling—not a fixed multi-year cluster taxonomy. Full article

Modern military decision-making demands real-time integration of structured knowledge, causal reasoning, and dynamic operational context. We introduce ARES-KG (Actionable & Reasoned Edge Support over Knowledge Graphs), a hybrid decision-support framework whose central contribution is the integration of explicit causal graph semantics—relations such as BLOCKS_ROUTE, LIMITS_MOBILITY_OF, and DELAYS, elevated to first-class queryable edges—into an LLM–KG pipeline. This design lets commanders trace multi-order operational effects (e.g., bridge destruction → mobility degradation → resupply delay → mission slippage) and answer counterfactual queries through deterministic graph traversal rather than free-form LLM speculation. Three supporting elements operationalize the central claim: a closed-loop NL→Cypher interaction layer that makes the causal layer accessible at staff tempo with full auditability; a lightweight ontology-driven CSV→Neo4j architecture suitable for hybrid edge-cloud deployment; and an eight-dimensional human–AI evaluation rubric in which one dimension, Causal Foresight, directly tests the central claim. In a synthetic brigade-level case study, ARES-KG generated transparent, explainable reasoning chains and exposed hidden multi-hop dependencies across sustainment, maneuver, fires, ISR, and C2. In a small-scale study with 10 active-duty officers spanning ranks from second Lieutenant to Colonel, an ARES-KG–enabled LLM achieved a Decision Support Score in the upper band of the sample—at the field-grade rank-group mean and above every junior officer—while producing answers in seconds rather than minutes. ARES-KG thus represents a concrete step toward next-generation human–AI collaborative command systems that augment, rather than replace, expert judgment under operational time pressure. Full article

Filament–wound carbon fiber composites are widely used in lightweight structural applications, where their mechanical performance is strongly affected by manufacturing-induced heterogeneities. In this study, the tensile behavior of carbon fiber composite specimens produced by filament winding was investigated using Digital Image Correlation (DIC) to obtain full-field strain measurements. Uniaxial tensile tests were performed while monitoring the spatial distribution of strain over the specimen surface. Beyond conventional global stress–strain characterization, DIC enabled the identification of significant strain heterogeneity both within individual specimens and among different specimens manufactured under the same nominal conditions. Localized strain concentrations were observed to develop in specific regions, revealing non-uniform deformation patterns that were not captured by global measurements alone. The results demonstrate that, despite similar global mechanical responses, substantial variability exists at the local scale. This intra and inter-specimen heterogeneity highlights the influence of filament winding architecture and local variability on tensile performance. The study underscores the limitations of relying solely on global measurements and emphasizes the capability of DIC to provide deeper insight into strain distribution and damage initiation mechanisms. These findings support the use of full-field optical techniques as a powerful tool for the mechanical characterization and quality assessment of filament–wound composite structures. Full article

Severe Cu and Pb enrichment in loess areas of northwestern China, mainly associated with mining and smelting activities, has increased the demand for efficient soil decontamination. Electrokinetic (EK) remediation is a promising in situ technology because it can drive ionic contaminants through low-permeability porous media with limited excavation and relatively low secondary disturbance. In this study, the effects of electric field strength, electrode type, and catholyte pH on Cu and Pb removal from contaminated loess were systematically evaluated using a large-scale EK reactor. The full name of EKG is electrokinetic geosynthetics. During treatment, pH, electrical conductivity, electric current, cumulative electroosmotic flow (EOF), and the spatial distributions of Cu and Pb were monitored. Increasing the electric field from 1.0 to 2.0 V cm⁻¹ increased current and EOF and accelerated anodic acid-front propagation, but it also strengthened cathodic alkalization and precipitation. Compared with graphite electrodes, electrokinetic geosynthetics (EKG) electrodes maintained higher current and EOF, generated stronger acidification, and increased Cu and Pb removal by approximately 25% and 5%, respectively. Among the tested catholyte conditions, pH 7.0 provided the best balance between electromigration and electroosmosis, achieving overall soil-phase removal efficiencies of approximately 19.0% for Cu and 8.0% for Pb. These results show that coordinated regulation of the electric field, electrode architecture, and electrolyte chemistry can mitigate the focusing effect in loess, although further enhancement is still required for field-scale decontamination. Full article

This work presents a comprehensive review of axion physics through the generative lens of a novel theoretical framework: Real-Now-Front (RNF) cosmology. Moving beyond the standard treatment of the axion as a fundamental particle in a pre-existing spacetime, we systematically reinterpret it as a specific collective excitation, a “twist” mode, arising from the alignment dynamics of the more fundamental Chronon field, from which spacetime itself emerges. Within this paradigm, the axion’s mass, its couplings to photons and matter, and the symmetry-breaking scale $f_a$ are not independent parameters but are derived from the microscopic stiffness and correlation length of the Chronon field, governed by the Temporal Coherence Principle. We re-examine the entire axion landscape, including benchmark models (KSVZ, DFSZ, ALPs) and the full spectrum of experimental constraints from terrestrial haloscopes, helioscopes, and astrophysical environments, translating them into probes of Chronon alignment dynamics. Furthermore,this generative framework yields unique, testable predictions, such as emergent bimetric effects and primordial black hole seeds from closed domain walls, providing independent avenues for falsification. By synthesizing established knowledge with this foundational new perspective, the review aims to establish a unified basis for the next generation of axion searches, positioning them as direct tests of the microscopic architecture of emergent spacetime, leveraginga multi-decade, multi-messenger observational campaign. Full article

High-altitude, low-pressure environments significantly reduce the insulation strength of air gaps, posing severe risks to live-line working on Ultra High Voltage and Extra High Voltage (UHV/EHV) transmission lines. To address this challenge and ensure operational safety, this paper proposes a predictive gap discharge voltage calculation model based on the dynamic coupling of time-varying electric fields and space charge. Unlike existing approaches that rely on static, geometry-dependent empirical corrections, the proposed model achieves high predictive capability by intrinsically mapping air relative density and absolute humidity to dynamically modify key microscopic discharge parameters, including the effective ionization coefficient, attachment coefficient, and streamer internal electric field strength. This physical framework enables the successful simulation of the complete progression from streamer inception to leader development and final breakdown, thereby calculating the 50% breakdown voltage under varying altitudes and gap distances. To rigorously validate the proposed model, breakdown tests were conducted using simplified sphere–plane gaps and full-scale simulated gaps between a human worker and a tower window at altitudes of 23 m and 2100 m. Additionally, third-party experimental datasets were utilized for comprehensive comparative analysis. The results demonstrate that the model’s predictive values align excellently with multi-source experimental data, establishing its high accuracy and practical engineering value for complex electrode configurations under diverse high-altitude conditions. Full article

Inter-turn insulation failure is the primary cause of dry-type air-core reactor burnout, yet early detection remains challenging due to weak power-frequency fault signatures. This paper proposes an integrated diagnostic framework combining impulse oscillation testing, electromagnetic simulation, and a physics-informed graph neural network. A scaled-down four-layer parallel reactor model and an impulse oscillation platform are developed to extract dynamic equivalent inductance and resistance as sensitive fault indicators. Validated finite element simulations reveal that inter-layer insulation near high-voltage terminals endures the highest electric field stress, with local field strength increasing nearly eightfold under short-circuit faults. For fault localization, a Spatio-Temporal Physics-Informed Graph Neural Network (ST-PIGNN) is constructed, representing winding topology as a heterogeneous graph and embedding electromagnetic transient equations as physical constraints. On a test set of 120 samples, the proposed method achieves 94.17% fault layer classification accuracy and 6.84% axial localization mean absolute error under low-noise conditions, and maintains 85.83% accuracy with 8.12% error under strong-noise interference. The proposed method is currently at the proof-of-concept stage, and further validation on full-scale reactors is required before field deployment. Full article

Beam–column joints are critical elements in reinforced concrete (RC) frame structures. They are subjected to complicated load mechanisms in the event of earthquakes, which often leads to non-ductile damage in the form of shear cracking failure and concrete spalling. With recent advances in computer vision techniques, an image-based methodology is implemented for effectively assessing the seismic damage of RC beam–column joints. Specifically, this study integrates digital image correlation (DIC)-derived strain fields with microplane damage theory to identify concrete surface damage, and subsequently, fractal dimension analysis is employed to quantitatively evaluate the damage metric. The proposed image-based analysis procedures are implemented to investigate the damage evolution of six full-scale RC beam–column joints subjected to quasi-static loading tests. The damage results derived using fractal dimension analysis are compared with those computed using conventional mechanics-based damage models. It is observed that the fractal-based damage index of the RC joints agrees reasonably well with the stiffness-based damage index. The damage curves reveal that the DIC-assisted fractal dimension analysis provides an effective means for automated identification of the surface damage pattern as well as damage progression of RC beam–column joints under seismic loading or other complex loading scenarios. Full article

Low-frequency impact sound control remains a critical challenge for floating floor systems. Conventional resilient underlayment materials exhibit insufficient damping and are prone to long-term deformation, making stable low-frequency sound insulation difficult to achieve. This study presents the development of a composite floating floor underlayment comprising recycled rubber granules, polymer resin, and quartz sand. Based on the constrained layer damping-inspired (CLD-inspired) perspective, the vibration attenuation and noise reduction mechanism is elucidated, and the material’s physical properties, mechanical behavior, microstructure, and acoustic performance are systematically investigated. The results indicate that excessively large rubber granules aggravate curing shrinkage cracking. Optimal processing characteristics are achieved with a binder content of 20 wt% and a rubber granule size of 50 mesh. Laboratory characterization reveals that, compared with conventional cross-linked polyethylene (XLPE) foam underlayments, the proposed composite underlayment reduces the impact sound pressure level by an average of 3–5 dB in the low-frequency band below 250 Hz, and the overall sound insulation performance is improved by 10.77%. Dynamic mechanical analysis shows the composite storage modulus declines from 280 MPa at −20 °C to 10 MPa at 80 °C, while the loss factor remains above 0.2 under typical indoor conditions. Such stable viscoelastic behavior enables efficient shear dissipation of low-frequency vibration energy under the CLD-inspired mechanism. Full-scale field testing combined with long-term observation over 3000 loading cycles demonstrates excellent structural compatibility between the underlayment and the gypsum screed, with no cracking or appreciable deformation observed during prolonged service. The weighted impact sound improvement index (ΔLw) attains 15 dB. These findings verify that the CLD-inspired composite underlayment simultaneously achieves efficient low-frequency impact sound control and superior long-term structural stability, providing an innovative material solution and design strategy for impact noise mitigation in residential floating floor applications. Full article

Conventional masonry infill walls can significantly alter the seismic response of framed buildings and often produce damage patterns incompatible with resilience-based seismic design. Dry-jointed sliding masonry wall systems have therefore emerged as deformation-tolerant alternatives that accommodate drift through controlled interface motion rather than damage accumulation. This study investigates the sequential in-plane (IP) and out-of-plane (OOP) behavior of such systems considering wall thickness, openings, and boundary detailing. Six full-scale specimens were tested, including thick- and thin-wall reference specimens, thick-wall specimens with window openings, and thin-wall specimens with door openings. IP performance was evaluated using global hysteretic and energy-based response parameters, whereas OOP behavior was assessed through load–displacement response, an equivalent acceleration index, and selected image-based displacement fields. The results show that IP drift was mainly accommodated through distributed sliding along horizontal interfaces and local block rotation, without diagonal compression strut formation or brittle cracking, even at drift ratios up to approximately 3.5%. Wall thickness improved IP strength, stiffness, shear resistance, and cumulative energy dissipation, while openings mainly affected deformation compatibility and load-transfer continuity. Under OOP loading, wall thickness and boundary continuity increased stiffness and capacity while enabling resistance mobilization at smaller displacement levels. As inertia-based comparison indicators, boundary-enhanced thick- and thin-wall specimens reached equivalent acceleration capacities of 3.41 g and 1.64 g, respectively. Overall, the system reduced IP damage accumulation, but adequate OOP stability requires appropriate wall thickness, unit geometry, and boundary detailing. Full article

To address prevalent industrial challenges, including the high cost of fabricating microstructures via photolithography and 3D printing, impurity residues easily generated by conventional physical/chemical pore-forming techniques, and the limited sensitivity of regular capacitive sensors, this paper innovatively proposes an integrated low-temperature in situ gas foaming strategy using ammonium bicarbonate for the fabrication of porous TPU-based ionic gels. Relying on the complete gaseous decomposition property of ammonium bicarbonate upon heating, a three-dimensionally interconnected continuous porous network is spontaneously constructed inside the polymer matrix. Thermoplastic polyurethane (TPU) is selected as the continuous polymer phase, and [EMIM][TFSI] imidazolium ionic liquid is blended as the ion source to synthesize composite ionic gel substrates. A PDMS composite slurry filled with graphene is employed to prepare flexible substrates, followed by low-temperature oxygen plasma surface modification to introduce polar functional groups such as hydroxyl and carboxyl onto electrode surfaces. A standard sandwich-structured ionic pressure sensor with the configuration of “top modified electrode—porous ionic gel dielectric layer—bottom modified electrode” is finally assembled. The porous framework and modified electrodes constitute a dual synergistic enhancement system: the porous structure markedly reduces the equivalent elastic modulus of the gel and improves its compressive deformation capacity; polar-modified electrodes optimize the interfacial compatibility between electrodes and gels, shorten ion migration paths and lower interfacial contact resistance. Systematic calibration of multiple batches of parallel samples reveals that the as-fabricated sensor achieves a high sensitivity of 25.3 kPa⁻¹ across the full measuring range from 0 to 1000 kPa with a linear fitting coefficient R² = 0.992. The loading response time and unloading recovery time of the device are 60 ms and 80 ms respectively, with a performance degradation of less than 3% after 1000 consecutive loading–unloading cycles, featuring low hysteresis error and excellent signal repeatability. Multi-scenario in vivo wearable tests on human subjects verify that the device can precisely capture subtle fluctuations of radial artery pulse and periodic laryngeal deformation during swallowing, distinguish characteristic waveform patterns of various English words according to differences in vocal cord vibration, and accurately detect bending motions when attached to finger joints. The entire fabrication process adopts common chemical raw materials and standard laboratory equipment without expensive micro-nano processing facilities, featuring convenient raw material procurement and high process fault tolerance, which enables large-area coating-based mass production. This work delivers a novel technical route for the low-cost large-scale production of high-performance ionic flexible sensors and bears significant industrialization reference value for applications in wearable medical monitoring, bionic robotic electronic skin, flexible human–machine interactive touch panels and other related fields. Full article

Piles with continuous helix (referred to herein as “screw pile”) is a new configuration of helical piles. It features a continuous helix spiraling several pitches around a smooth shaft forming a “threaded shaft”. This study investigates the compressive capacity and behavior of helical and screw piles using 3D numerical models calibrated and validated against full-scale field testing. The bearing capacity factor, $N_c$, for helical piles is back-calculated from the numerical results and compared against standard theoretical assumptions to evaluate their accuracy in predicting ultimate capacity. Parametric studies are conducted considering screw piles configuration, including shaft diameter, pitch size, helix diameter, as well as soil strength. The results reveal that shaft resistance accounts for up to 89% of the total capacity. Analysis of load distribution, shear contours, and displacement contours at failure allowed for the identification of different failure modes of soil adjacent to the pile’s threaded shaft: Individual Bearing Mode (IBM), Cylindrical Shear Mode (CSM), and a combined mode. The study identifies specific parametric thresholds for these modes in both sand and clay layers. Furthermore, varying clay strength is found to alter the development of the shear surface, transitioning from localized bearing to continuous shearing along the threaded shaft. Finally, apparent shaft resistance factors, $\alpha$ and $\beta$, are back-calculated to provide practical parameters for evaluating the resistance of threaded shafts in layered soil. Full article

High-speed railway embankments constructed over karst-prone ground conditions are often challenged by weak soils and subsurface cavities, which can lead to instability and excessive settlement. This study presents a full-scale field investigation conducted in the El-Gharbaniyat area, west of Alexandria, Egypt, where a pile–cap ground improvement system was implemented to support a high-speed railway embankment founded on clayey and silty soils overlying fractured limestone. A comprehensive site investigation program was performed, including 28 boreholes and integrated geophysical surveys using Electrical Resistivity Tomography (ERT) and Seismic Tomography (ST), enabling improved identification of weak zones and cavity-prone formations. Based on these findings, a pile–cap system was designed using reinforced concrete piles of 0.60 m diameter and an average length of 29 m, arranged in a 4 × 4 m grid and capped with reinforced concrete footings to ensure efficient load transfer to deeper competent strata. The system performance was validated through laboratory testing and full-scale in situ pile load tests. The average 28-day compressive strength of 122 tested piles reached approximately 50 MPa, exceeding the design value by approximately 30%. Load test results showed settlements ranging from 1.08 to 2.76 mm at the working load (2200 kN) and 2.16 to 5.10 mm at the maximum load (3300 kN), all well below allowable limits. Comparative evaluation indicated that the proposed system achieves significant material savings (>90%), lower treatment cost (150 USD/m²), reduced carbon emission (5.7 t per pile), and shorter construction duration (7 h per pile). These findings confirm that the pile–cap system provides a robust, cost-effective, and environmentally efficient solution for ground improvement in karst environments. Full article

Suspended ceiling systems are among the most seismically vulnerable non-structural components in buildings, posing significant life-safety risks and economic losses, yet understanding their full-field kinematic behavior under seismic loading remains a major experimental challenge. Conventional contact sensors offer limited spatial coverage and can alter the dynamic properties of lightweight panels due to mass loading. In contrast, non-contact optical alternatives are rarely feasible in shake-table environments due to restricted viewing angles, extensive areal coverage requirements, and the risk of equipment damage from falling panels. This study proposes an end-to-end three-dimensional displacement measurement framework for large-scale shake-table testing of suspended ceiling systems, employing consumer-grade cameras with purpose-built tools that cover the complete experimental workflow, including motion-based video trimming, semi-automated calibration, a robust multi-stage image-tracking pipeline that maintains trajectory continuity under extreme inter-frame displacements, and a ceiling system motion visualization and analysis tool. The framework was validated through a full-scale shake-table experiment continuously tracking 324 spatial nodes across 81 ceiling panels, achieving an RMSE below 3 mm in all spatial directions and exact peak-frequency agreement in 9 out of 10 test cases. A parallel processing architecture reduced total processing time from over 27 h to under 10 min without GPU acceleration, and six-degree-of-freedom rigid-body analysis resolved the complete panel failure sequence from constrained oscillation through multi-axis rotation to gravitational free fall, a level of kinematic detail unattainable with conventional instrumentation. This framework establishes a practical, scalable foundation for full-field seismic performance assessment of non-structural systems where conventional instrumentation is physically or logistically infeasible. Full article