Search Results (395)

Wireless Sensor Networks (WSNs) are pivotal for data acquisition, yet reliability is severely constrained by routing voids induced by sparsity, uneven energy, and high dynamicity. To address these challenges, the Hybrid Acoustic-Optical Adaptive Void-handling Protocol (HAO-AVP) is proposed to satisfy the requirements for highly reliable communication in complex underwater environments. First, targeting uneven energy, a reinforcement learning mechanism utilizing Gini coefficient and entropy is adopted. By optimizing energy distribution, voids are proactively avoided. Second, to address routing interruptions caused by the high dynamicity of topology, a collaborative mechanism for active prediction and real-time identification is constructed. Specifically, this mechanism integrates a Markov chain energy prediction model with on-demand hop discovery technology. Through this integration, precise anticipation and rapid localization of potential void risks are achieved. Finally, to recover damaged links at the minimum cost, a four-level progressive recovery strategy, comprising intra-medium adjustment, cross-medium hopping, path backtracking, and Autonomous Underwater Vehicle (AUV)-assisted recovery, is designed. This strategy is capable of adaptively selecting recovery measures based on the severity of the void. Simulation results demonstrate that, compared with existing mainstream protocols, the void identification rate of the proposed protocol is improved by approximately 7.6%, 8.4%, 13.8%, 19.5%, and 25.3%, respectively, and the void recovery rate is increased by approximately 4.3%, 9.6%, 12.0%, 18.4%, and 24.2%, respectively. In particular, enhanced robustness and a prolonged network life cycle are exhibited in sparse and dynamic networks. Full article

Efficient soil conditioning is critical for controlling the mechanical behavior of sandy muck in earth pressure balance (EPB) shield tunneling. This study investigates the undrained shear response of sand conditioned with slurry, a newly developed bubble–slurry, and foam under vertical stresses of 0–300 kPa, considering different injection ratios and shear rates. Under atmospheric pressure, conditioning reduces both peak and residual shear strengths by more than 90% compared with untreated sand. Foam- and bubble–slurry-conditioned sands show stable strength within 6 h; after 24 h, peak strength increases from 0.39 to 4.67 kPa for foam-conditioned sand but only from 0.67 to 0.84 kPa for bubble–slurry-conditioned sand. Shear strength increases nearly linearly with shear rate, especially for residual strength. Pore-scale mechanisms were interpreted by considering bubble proportion and size, pore-fluid rheology, and surface tension. Rheology governs whether dynamic or viscous resistance dominates at different shear rates, while surface tension influences stress transmission through bubble stability and interparticle lubrication. The void ratio range of e/e_max = 1.00–1.36 was identified as achieving low shear strength and good flowability. Field application in Jinan Metro Line R2 confirmed that combined conditioning (25% foam + 13% slurry) reduced cutterhead torque by about 37% without spewing. Full article

This study examines the torsional behavior of an additively manufactured bushing featuring a unique topology, which includes a flexible gyroid core and rigid inner and outer sleeves. The bushing is designed and fabricated using two materials: thermoplastic polyurethane (TPU) and polylactic acid (PLA), which are interpenetrated in successive layers throughout the bushing’s thickness. First, tensile mechanical tests are conducted on both materials with different infill patterns. The 45/135 infill proves to be the most suitable, providing good stiffness, strength, ductility, and data reproducibility. Additionally, the effectiveness of the interlocking created between the two materials through the printing process is evaluated by testing different overlap lengths. With an overlap of 2 mm, the extrusion process remains unaffected, minimizing voids and defects while ensuring strong interlayer bonding. Next, the designed bushing is subjected to torsional loading under both single and repetitive angular rotations, and its response is measured in terms of torque. The aim of this study is to evaluate the suitability of TPU and PLA materials for developing a design intended for dynamic mechanical environments, serving as a proof of concept. The quasi-static results indicate the presence of local damages and a viscoelastic response of the bushing during twisting, while also demonstrating its strong ability to withstand significant angles of rotation. Quasi-static results indicate local damage and the bushing’s viscoelastic response during twisting, as well as its ability to withstand significant angles of rotation. Full article

This study utilizes the drift–flux model to develop a new flow pattern map designed to facilitate an accurate estimation of gas void fraction (${\alpha }_g$) in vertical upward flow. The map is parameterized by mixture velocity ($u_m$) and gas volumetric quality (${\beta }_g$), integrating transition criteria from the established literature. For applications characterized by significant pressure gradients, such as gas lift, these criteria were reformulated as functions of pressure, enabling direct estimation from operational data. A critical component of this methodology for the estimation of ${\alpha }_g$ is the estimation of the distribution parameter ($C_0$). An analysis of experimental data, spanning pipe diameters from 1.27 to 15 cm across the full void fraction ranges (${0<\alpha }_g<1$), reveals a critical ${\alpha }_g$ threshold beyond which $C_0$ exhibits a distinct decreasing trend. To characterize this phenomenon, the parameter of the distribution-weighted void fraction (${\alpha }_c={\alpha }_g{C}_0$) is introduced. This parameter, representing the dynamically effective void fraction, identifies the critical threshold at its inflection point. The proposed model subsequently defines $C_0$ using a two-part function of ${\alpha }_c$. This generalized approach simplifies the complexity inherent in existing correlations and demonstrates superior predictive accuracy, reducing the average error in ${\alpha }_g$ estimations to 5.4% and outperforming established methods. Furthermore, the model’s parametric architecture is explicitly designed to support the optimization and fine-tuning of coefficients, enabling future use of machine learning for various fluids and complex industrial cases. Full article

To study the creep compression characteristics and evolution mechanism of pressure-bearing graded crushed rock under constant load. Creep compression tests of crushed rock were conducted using the self-developed confined compression test system under different Talbot indexes and axial stresses. The axial displacement, void ratio, mass distribution, fractal dimension, and fragmentation of crushed rock during creep compression were analyzed. And the void ratio-fractal dimension model of crushed rock under pressure was established. The results reveal three-stage characteristics in axial displacement and void change, which correspond to rapid, attenuation, and stable change processes. The axial displacement and fragmentation amount are positively correlated with the axial stress and Talbot index, while the porosity is negatively correlated with them. The fractal dimension shows a positive correlation with axial stress and a negative correlation with the Talbot index. Additionally, a theoretical model was established to characterize the dynamic correlation between void ratio and fractal dimension during compression process, and its accuracy was verified, with a maximum error of only 0.0819. The research findings can provide insights for stability prediction and deformation control of crushed rock in engineering applications such as building foundation pits, ground treatment, and coal mine goafs. Full article

Ground settlement is readily induced by shield–tail gaps formed during tunneling, where soil loss must be compensated through backfill grouting. However, improper grouting control may trigger tunnel uplift, segment misalignment, and, after solidification, problems such as voids, cracking, and water ingress. Ensuring construction safety and long-term serviceability requires both reliable detection of grouting effectiveness and a mechanistic understanding of grout diffusion. This review systematically synthesizes sensing technologies, diffusion modeling, and intelligent data interpretation. It highlights their interdependence and identifies emerging trends toward multimodal joint inversion and real-time grouting control. Non-destructive testing techniques can be broadly categorized into geophysical approaches and sensor-based methods. For synchronous detection, vehicle-mounted GPR systems and IoT-based monitoring platforms have been explored, although studies remain sparse. Theoretically, grout diffusion has been investigated via numerical simulation and field measurement, including the spherical diffusion theory, columnar diffusion theory, and sleeve-pipe permeation grouting theory. These theories decompose the diffusion process of the slurry into independent movements. Nevertheless, oversimplified models and sparse monitoring data hinder the development of universally applicable frameworks capable of capturing diverse engineering conditions. Existing techniques are further constrained by limited imaging resolution, insufficient detection depth, and poor adaptability to complex strata. Looking ahead, future research should integrate complementary non-destructive methods with numerical simulation and intelligent data analytics to achieve accurate inversion and dynamic monitoring of the entire process, ranging from grout diffusion and consolidation to defect evolution. Such efforts are expected to advance both synchronous grouting detection theory and intelligent and digital-twin tunnel construction. Full article

This study developed a natural rubber (NR) composite reinforced with surface-modified pineapple leaf fibres (PALFs) and hemp fibres (HFs) using a layer-by-layer (sandwich-like) fabrication method. The objectives were to increase the utilisation of the natural fibres as reinforcing agents and to investigate the impact of silane fibre surface modification on the properties of the sandwich composites. Fibre surface characterisation was performed using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) to confirm the presence of functional groups from silane and cellulose. The wettability and adhesion properties of the modified fibres were also evaluated. The mechanical properties were investigated via single-fibre tensile tests. Composites with 50 phr silane-treated PALF showed the best compromise in terms of interface adhesion (48.3 mJ/m²) and tensile strength (6 MPa). This result was also supported by scanning electron microscopy (SEM), which revealed the absence of voids between the fibres and the NR matrix. Furthermore, dynamic mechanical analysis showed that the PALF composite treated with silane at 50 phr exhibited the best viscoelastic behaviour. NR composites with 50 phr silane-treated PALF have mechanical properties suitable for potential applications in engineering products. Full article

Traditional scholarship on early Chinese political geography has largely privileged textual analysis, often lacking quantifiable baselines for assessing spatial structure. Addressing this gap, this study utilizes the Shang-Zhou period Shandong region as a focal case to propose a replicable GIS framework—incorporating Kernel Density Analysis (KDA) and Voronoi diagrams—grounded in a null-hypothesis approach. Rather than attempting to simulate theoretical territories, these methods are employed to establish a purely geometric baseline for political space. Central to this study’s findings is the quantification of deviations from this geometric ideal. These measurable discrepancies—manifesting as “Voronoi voids” in mountainous zones and “scale violations” by major powers—serve as empirical indicators for interpreting the tangible impacts of topography, power dynamics, and resource allocation, such as the coastal salt fields identified via KDA. Ultimately, this study demonstrates that this deviation analysis framework functions as a vital quantitative complement to traditional institutional history, effectively elucidating the spatial logic and dynamic evolution of ancient political systems. Full article

The dynamic characterization of historical buildings located in a complex geological and seismological context is essential to assess seismic vulnerability and to guide conservation strategies. This study presents a non-invasive, ambient vibration-based, investigation of the Norman Castle of Aci Castello (Sicily, Italy), applying Horizontal to Vertical Spectral Ratio (HVSR), Horizontal to Horizontal Spectral Ratio (HHSR), and Random Decrement Method (RDM) to evaluate the structure’s dynamic behavior and potential Soil–Structure Interaction (SSI) effects. The fundamental site frequency, estimated within a broad plateau in the range 2.05–2.70 Hz, does not overlap with the structural frequencies of the castle, which range approximately from 6.30 Hz to 9.00 Hz in the N–S structural direction and from 3.50 Hz to 8.50 Hz in the E–W direction, indicating absence of global SSI resonance. However, the structure exhibits a complex multimodal response, with direction-dependent behavior evident both in spectral peaks and in damping ratios, ranging from 2.10–7.73% along N–S and 0.90–5.84% along E–W. These behaviors can be interpreted as possibly linked to structural complexity and the interaction with the fractured volcanic substrate, characterized by shallow cavities, as well as to the material degradation of the masonry. In particular, the localized presence of subsurface voids may induce a perturbation of the low-frequency ambient vibration wavefield (e.g., microseisms), producing a localized increase in spectral amplitude observed at Level I. The analysis indicates the absence of global SSI resonance due to the lack of overlap between site and structural fundamental frequencies, while significant local SSI effects, mainly related to cavity-induced wavefield perturbation, are observed and may represent a potential vulnerability factor. These findings highlight the relevance of vibration-based diagnostics for heritage vulnerability assessment and conservation strategies. Full article

Leakage from defective buried pipelines can lead to progressive soil erosion and void formation, ultimately resulting in ground collapse or sinkhole development. To better understand the underlying mechanisms of this process, this research utilizes a coupled computational fluid dynamics (CFD)–discrete element method (DEM) modeling approach to investigate soil erosion processes driven by water leakage from defective underground pipelines. The numerical model captures fluid–particle interactions at both macroscopic and microscopic scales, providing detailed insights into erosion initiation, void zone evolution, and particle transport dynamics under varying hydraulic and geometric conditions. Parametric studies were conducted to evaluate the effects of exfiltration pressure, defect size, and particle diameter on erosion behavior. Results show that erosion intensity and particle migration increase with hydraulic pressure up to a threshold, beyond which compaction and particle bridging reduce sustained transport. The intermediate defect size (12.7 mm) consistently produced the most continuous and stable erosion channels, while smaller and larger defects exhibited localized or asymmetric detachment patterns. Particle size strongly influenced erosion susceptibility, with finer grains mobilized more readily under the same flow conditions. The CFD–DEM simulations successfully reproduce the nonlinear and self-reinforcing nature of internal erosion, revealing how hydraulic gradients and particle rearrangement govern the transition from local detachment to large-scale cavity development. These findings advance the understanding of subsurface instability mechanisms around leaking pipelines and provide a physically consistent CFD–DEM framework that aligns well with published studies. The model effectively reproduces the key stages of erosion observed in the literature, offering a valuable tool for assessing erosion-induced risks and for designing preventive measures to protect buried infrastructure. Full article

We investigate the explosive-rupture behavior of porcelain hollow bushings using a representative 500 kV SF₆ incident as the reference case. Finite-element simulations are performed for both the static response and the rupture process. Results show that internal SF₆ pressure drives the maximum equivalent (von Mises) stress to the flange, while strain localizes near the bushing mid-span. These findings highlight the cement–grout potting between the porcelain shell and flange, the waterproofing treatment, and the mid-span bonded joint as key manufacturing control points. Dynamic simulations further indicate that comparing the explosive-equivalent energy of the SF₆ pressure impulse with the gas expansion (burst) energy enables diagnosis of the failure mode. From the viewpoint of fragment kinetic energy, the analysis indirectly verifies that rupture is initiated by intrinsic porcelain defects and subsequent crack propagation. The simulated fragment morphology and ground dispersion agree with field observations from the actual event, underscoring the critical role of microcracks in brittle fracture. Accordingly, optimizing firing processes to reduce internal cracks and voids—via raw-material control and firing-temperature optimization—is essential for reliability improvement and life extension. The results provide a practical reference for the design and long-term operation of porcelain bushings. Full article

This study develops and validates the concept of Regulatory Cultural Stewardship (RCS) as a dynamic capability that enables small and medium-sized enterprises (SMEs) to achieve sustainable AI-enabled digital transformation (AIEDT) in a volatile emerging economy. RCS empowers SMEs to harmonize regulatory compliance with cultural legitimacy, a critical nexus for fostering sustainable business practices and long-term resilience (economic viability and social legitimacy), in line with the global sustainable objectives. Using survey data from 391 Pakistani SMEs and Partial Least Squares Structural Equation Modeling (PLS-SEM), we find that four key AIEDT drivers explain 65.1% of the variance in AI innovation, with Technological Infrastructure and Policy and Ecosystem Support as dominant enablers. AI innovation fully mediates the relationship between AIEDT drivers and sustainable business performance. RCS not only enhances SME performance directly but also strengthens the AI innovation–business performance linkage as a significant moderator. Sectoral analysis reveals that services benefit most from Socio-Cultural Readiness, while manufacturing and primary sectors depend more on policy infrastructure and RCS. Significantly, RCS is validated as a distinct construct, integrating compliance and cultural alignment, rather than a subset of existing factors like policy support or cultural readiness. The study emphasizes the importance of scalable AI infrastructure, workforce upskilling, and internal cultural adaptation, while urging policymakers to stabilize AI governance frameworks to ensure a sustainable and equitable digital transition. The findings advance theory by conceptualizing RCS as a meta-capability bridging institutional voids and socio-cultural dynamics and offer practical insights for policymakers and managers seeking to implement ethically aligned and sustainable AIEDT strategies in emerging markets. At a conceptual level, RCS is ethically grounded in global AI principles, including fairness, accountability, and transparency, ensuring that cultural alignment never overrides human-centered values. Full article

Reliable estimates of soil stiffness and energy dissipation are essential for dynamic-response design. This study benchmarks machine learning models for predicting shear modulus (G) and damping ratio (D) using 2738 resonant-column measurements. After data quality control and F-test feature screening, five model families—decision trees and ensembles, support-vector machines, Gaussian-process regression, neural networks, and linear baselines—were trained under uniform 10-fold cross-validation and evaluated with R², RMSE, MAE, and MSE, while recording training time to reflect practical constraints. Results show that model choice materially affects performance. For G, a bagged ensemble of trees delivered the best accuracy (R² = 0.9827) with short training times; single trees provided transparent, fast screening models. For D, tree-based ensembles again performed strongly (R² up to 0.8565), while a rational-quadratic Gaussian-process model offered competitive accuracy (R² ≈ 0.81) together with prediction intervals that support risk-aware design. Feature influence aligned with soil mechanics: G was most sensitive to effective confining pressure (σ′0), initial void ratio (e0), and density (ρ); D was governed mainly by overconsolidation ratio (OCR), depth (z), σ′0, and plasticity, with notable interactions among stress, strain amplitude (γ), and moisture state. The findings provide practice-oriented guidance: use bagged trees for routine predictions of G and D, and add Gaussian-process regression when uncertainty quantification is required. The approach complements laboratory testing and supports safer, more economical dynamic-response design. Full article

Mixing zones in carbonate coastal aquifers are dynamic interfaces where freshwater and seawater converge, triggering complex biogeochemical processes. This study investigates diagenetic barite (BaSO₄) precipitation within such a mixing zone in the dolomitic aquifer of the Sierra de Gádor (SE Spain). Three sectors were analyzed: two active mixing zones—one associated with submarine discharge and the other affected by marine intrusion—and an uplifted, fossilized Pleistocene mixing zone. Mineralogical, petrographic, and geochemical analyses reveal extensive dissolution of the dolomitic bedrock, forming polygonal voids and fracture-controlled porosity, frequently covered by Fe and Mn oxides. Barite crystals were identified exclusively in the Fe oxide precipitates at depths where 80% of seawater is reached. The saturation index for barite in groundwater suggests near-equilibrium conditions across the fresh–brackish–saline transition; however, barite precipitation is localized where Fe oxides act as a geochemical barrier, concentrating Ba and enabling nucleation. SEM imaging shows well-formed euhedral barite crystals up to 100 µm in size. This form of crystallization would be similar to the marine diagenetic barite formation models involving organic matter degradation and Ba remobilization, translated to a coastal aquifer setting in this study. Trace metal analyses show significant enrichment of Pb (up to 20 wt%) and other elements (Zn, Ni, and Co), suggesting potential for ore-forming processes if redox conditions shift. This work proposes a conceptual model for diagenetic barite formation in coastal aquifers, emphasizing the role of Fe and Mn oxides as reactive substrates in metal cycling at the land–sea interface. Full article

The objective of this study is to analyze spatial entropy flows that reveal the directional dynamics of climate change—patterns that remain obscured in traditional statistical analyses. This approach enables the identification of pathways for “climate information transport”, highlights associations with atmospheric circulation types, and allows for the localization of both sources and “informational voids”—regions where entropy is dissipated. The analytical framework is grounded in a quantitative assessment of long-term climate variability across Europe over the period 1901–2010, utilizing Shannon entropy as a measure of atmospheric system uncertainty and variability. The underlying assumption is that the variability of temperature and precipitation reflects the inherently dynamic character of climate as a nonlinear system prone to fluctuations. The study focuses on calculating entropy estimated within a 70-year moving window for each calendar month, using bivariate distributions of temperature and precipitation modeled with copula functions. Marginal distributions were selected based on the Akaike Information Criterion (AIC). To improve the accuracy of the estimation, a block bootstrap resampling technique was applied, along with numerical integration to compute the Shannon entropy values at each of the 4165 grid points with a spatial resolution of 0.5° × 0.5°. The results indicate that entropy and its derivative are complementary indicators of atmospheric system instability—entropy proving effective in long-term diagnostics, while its derivative provides insight into the short-term forecasting of abrupt changes. A lag analysis and Spearman rank correlation between entropy values and their potential supported the investigation of how circulation variability influences the occurrence of extreme precipitation events. Particularly noteworthy is the temporal derivative of entropy, which revealed strong nonlinear relationships between local dynamic conditions and climatic extremes. A spatial analysis of the information entropy field was also conducted, revealing distinct structures with varying degrees of climatic complexity on a continental scale. This field appears to be clearly structured, reflecting not only the directional patterns of change but also the potential sources of meteorological fluctuations. A field-theory-based spatial classification allows for the identification of transitional regions—areas with heightened susceptibility to shifts in local dynamics—as well as entropy source and sink regions. The study is embedded within the Fokker–Planck formalism, wherein the change in the stochastic distribution characterizes the rate of entropy production. In this context, regions of positive divergence are interpreted as active generators of variability, while sink regions function as stabilizing zones that dampen fluctuations. Full article