Search Results (37,633)

Accurate identification of complex crack networks with branching and intersecting topologies remains a challenge in aerospace and civil engineering. Conventional non-destructive testing techniques are constrained by limited coverage and equipment access requirements, while model-based inverse methods face the curse of dimensionality and high computational cost when characterizing intricate crack morphologies. To address these limitations, a Binary-encoded Transformable Modular Component (BTMC) method is proposed, which abstracts complex crack morphologies into combinations of modular components representing elementary crack topological operations and encodes their parameters into a unified binary genotype. This representation converts the high-dimensional continuous inverse problem into a discrete combinatorial optimization task over a bounded search space, and the extended finite element method is coupled with a genetic algorithm for forward analysis and parameter optimization. Numerical simulations covering non-intersecting cracks, intersecting networks, and irregular morphologies beyond the component library demonstrate that the method maintains stable identification accuracy under measurement noise up to 10%. Experimental verification on a metal tensile plate and a wing surface curved-shell structure confirms that the identified configurations are mechanically consistent with the measurements, with the strain-response error on the wing surface reduced from 8.67% for the traditional genetic algorithm to 2.27% for BTMC. Across all test cases, the BTMC method converges in fewer generations with a total identification time of approximately 16 min on average, which provides a computationally efficient framework for online structural health monitoring of aircraft structures. Full article

Most experimental RF/microwave glucose sensors have to operate in conjunction with a vector network analyzer (VNA). Not only is a VNA bulky and expensive, but the process of a VNA-based glucose measurement is extremely tedious. For the first time, a fully customized system has been developed to demonstrate the feasibility of contact-based glucose measurement without any VNA. Method: A sweeping RF synthesizer (LMX2595) was used for scanning a specific range of frequencies that covered the perturbed frequencies of a membrane-supported glucose sensing head (MSSH), which was around 1.3 GHz. During the frequency sweeping process, a gain–phase detector (AD8302) was used to capture the gain, which was one of the parameters for determining the MSSH’s reflection coefficients (S11). During the frequency sweeping process, the measured voltage gains and phases from the AD8302 module were serially sent to a computer, where the reflection coefficients were retrieved and smoothed with a Savitzky–Golay filter augmented with a multilevel neural network implemented in PyTorch 2.13.0. Results: The proposed system was able to conduct continuous measurements on glucose concentrations from 0 to 111 mg/dL with no VNA and no manual intervention. Moreover, it was able to generate highly reproducible results consistent with those of a commercial VNA. Conclusion: The proposed non-VNA glucose sensing system was able to continuously measure the concentrations of a glucose–water solution with results consistent with those of a VNA. Full article

Perforation damage can significantly reduce the load-carrying capacity of aluminum alloy plates. Adhesive–rivet hybrid repair combines the continuous load-transfer capability of adhesive bonding with the reliable mechanical connection provided by riveting; however, quantitative methods for matching damage size, rivet parameters, and adhesive load-carrying capacity remain insufficient. In this study, perforated 2A12-T4 aluminum alloy plates were investigated. Based on the equal-strength criterion and load-transfer equilibrium, a strength-matching relationship between the adhesive layer and blind rivets was established, and a residual-strength assessment method for the repaired structure was proposed. Two typical two-part epoxy adhesives with different shear strengths, Araldite-2015 and Lord 320/322, which have application backgrounds in aerospace structural joining and repair, were selected. Combined with blind rivets of different load-carrying capacities, they formed strong-adhesive/weak-rivet and weak-adhesive/strong-rivet configurations to investigate the mechanical response under different adhesive–rivet strength-matching conditions. Quasi-static tensile tests, digital image correlation (DIC) measurements, and finite element analyses incorporating a cohesive zone model and a ductile damage criterion were performed to investigate load distribution and failure behavior. The results show that the maximum deviation between the finite element predictions and the experimental failure loads is 5.02%. Before significant adhesive failure, the adhesive layer carries up to 67.25% of the transferred load, indicating a substantial load-sharing effect on the rivets. The hybrid-repaired structures mainly fail along the cross-section through the outermost rivet holes. The proposed residual-strength model shows agreement with the investigated experimental dataset, with a maximum deviation of 6.37%; because the reduction coefficient contains an empirical calibration component, broader predictive applicability requires independent validation. For the six repair configurations, the strength recovery ratios all exceed 74%, the maximum strengthening ratio reaches 55.49%, and the maximum value of the newly proposed repair ratio is 0.48 kN/g. Unlike previous studies that mainly focused on comparisons of joining methods, failure behavior, or individual process parameters, this study establishes a quantitative framework that links damage size and material load-carrying capacity with adhesive–rivet parameter matching and post-repair residual-strength assessment. The proposed method provides theoretical and experimental support for the design and strength evaluation of adhesive–rivet hybrid repairs for perforated aluminum alloy thin plates under fully cured conditions. Full article

Remote island buildings often operate under isolated environmental conditions where conventional water supply infrastructures are unavailable or unreliable. However, the lack of theoretical frameworks and integrated technologies for building-scale autonomous water supply remains a critical challenge in sustainable construction and resilient building development. Existing atmospheric water harvesting technologies mainly focus on material-level adsorption capacity or short-term water production performance, while systematic principles for integrating sorption materials, heat transfer structures, and renewable energy subsystems into autonomous building water systems remain insufficiently established. This study develops and validates an active, continuous atmospheric water harvesting (AWH) system utilizing MIL-101(Cr) coated on finned tubes. The system alternates cold water (25 °C) and hot water (50–70 °C during actual experiments; 50–80 °C in simulations) through the piping, allowing the two parallel modules to independently undergo adsorption and desorption phases-thereby breaking away from the traditional daily single-cycle mode. A coupled heat and mass transfer model is developed and validated using experimental measurements obtained from the MIL-101(Cr)-coated finned tube component, with root-mean-square deviations below 8.5% for all key parameters. Under simulated coastal island conditions (75–87% RH, 29–32 °C), the dual-module system achieves a water productivity up to 1.989 kg·m⁻²·day⁻¹ at a desorption temperature of 80 °C, with cycling frequencies reaching 9 cycles per module over 48 h. Parametric analysis reveals that synergy between desorption temperature (50–80 °C) and desorption extent (50–80%) governs daily water yield, while the per-cycle adsorption capacity remains stable at ≈0.91 g/g. Energy and economic analysis shows that the auxiliary electricity required ranges from 0.38 (50 °C) to 6.36 kWh·m⁻³ (80 °C), with a preliminary levelized cost of water of 1.85–3.2 USD·m⁻³ competitive with conventional island supply methods. Full article

Aircraft icing can substantially alter leading-edge geometry and degrade aerodynamic performance, highlighting the need for computationally efficient prediction methods during preliminary aircraft design. This study presents a two-dimensional reduced-order framework for airfoil ice-accretion prediction that couples a Hess–Smith potential-flow solver with Lagrangian droplet tracking, surface collection-efficiency reconstruction, a low-order freezing model, and an iterative geometry-update procedure. After each ice-accretion increment, the aerodynamic flow field and droplet trajectories are recomputed over the updated geometry, thereby capturing the coupled effects of ice growth, local flow acceleration, and downstream droplet impingement. A convergence study was performed to establish suitable surface and particle discretization. The predictive capability of the framework was assessed against four experimental NACA 23012 ice-accretion geometries representing streamwise and roughness-dominated configurations. The numerical predictions reproduced the location, extent, and principal morphological characteristics of the measured leading-edge deposits. Parametric investigations showed that the collection-efficiency distribution is governed primarily by the angle of attack, median volumetric diameter, and freestream velocity, whereas the maximum ice thickness is controlled predominantly by liquid water content and ambient temperature. Two-parameter response maps further revealed nonlinear interactions among droplet inertia, aerodynamic transport, incident water flux, freezing conditions, and geometry evolution. The proposed framework provides a practical, low-cost tool for preliminary icing assessment, sensitivity analysis, and rapid screening of atmospheric and operating conditions prior to higher-fidelity investigation. Full article

Objective: To evaluate whether structural entropy of liver histological sections reflects tissue disorganization in a rat model of constant light exposure (dark deprivation) and to explore its associations with morphofunctional parameters of hepatic remodeling. Methods: Male Wistar rats (n = 120) were divided into a control group (12:12 h light/dark) and a constant light group (24 h/day, 3 months). Biochemical, histological, immunohistochemical (p16, p21, p53, BMAL1, CLOCK, PER2, Ki-67) and ultrastructural parameters were assessed. Shannon entropy was calculated on hematoxylin and eosin-stained sections using a graph-based approach based on nuclear spatial distribution and size heterogeneity. Results: Constant light exposure caused a >2-fold decrease in serum melatonin, suppression of BMAL1 and CLOCK expression (3.7- and 3.5-fold, respectively), a rise in PER2 (+29.8%), and marked increases in p16 (23.8-fold), p21 (6.7-fold), p53 (+80.9%), steatosis, hyperglycemia, and mitochondrial dysfunction (decreased cristae count, reduced circularity index). Entropy increased by 21.4% and showed strong correlations with steatosis score (r = 0.93), p53-positive cells (r = 0.88), PER2-positive cells (r = 0.86), and an inverse correlation with melatonin (r = –0.81). Partial correlations adjusted for treatment revealed that entropy remained associated with local morphological and ultrastructural parameters but not with systemic biochemical markers, suggesting that entropy primarily reflects tissue-level remodeling. An exploratory regression model, albeit with substantial multicollinearity, explained 87.5% of entropy variance, with steatosis and circadian markers as major contributors. Conclusion: Constant light exposure induces hepatic alterations that share multiple features with aging-associated phenotypes, including steatosis, cellular senescence, mitochondrial dysfunction, and circadian disruption. Structural entropy is an exploratory quantitative index of tissue disorganization that correlates with key morphofunctional parameters of hepatic remodeling. However, because the study lacked aged comparator groups, melatonin replacement, recovery models, and independent validation, entropy should not be considered a validated biomarker of biological liver age. Its potential applicability in digital pathology and geroprotective research requires confirmation in future studies with appropriate experimental designs. Full article

Neoadjuvant chemotherapy (NAC) is the standard of care for locally advanced breast cancer, yet the molecular predictors of pathological response remain incompletely defined, particularly regarding microRNA (miRNA) dynamics. We investigated paired pre- and post-NAC miRNA expression profiles in relation to molecular subtype, residual cancer burden (RCB), and clinical timing parameters. Seven patients with invasive breast cancer (Luminal A n = 3, Luminal B n = 1, TNBC n = 2, HER2+ n = 1) who received NAC (AC-T or TCHP) were included in this pilot study. Small-RNA sequencing (NovaSeq X Plus, CeGaT GmbH, project S17293) was performed on 14 FFPE specimens (7 pre-NAC core needle biopsies, 7 post-NAC surgical specimens). Differential expression analysis used the paired Wilcoxon signed-rank test with Benjamini–Hochberg correction. Spearman correlations assessed associations between miRNA expression, RCB score, and clinical timing intervals. Candidate miRNAs were subsequently annotated using experimentally validated miRNA–target interactions. After filtering (≥ three counts in ≥ three samples), 759 miRNAs were analysed. No miRNA reached strict significance (padj < 0.05, |log₂FC| > 1.0) after multiple testing correction, consistent with the limited statistical power (n = 7). Under exploratory criteria (p < 0.10, |log₂FC| > 0.5), 156 candidate miRNAs were identified: 70 upregulated and 86 downregulated post-NAC. Leading candidates included hsa-miR-139-3p (+2.60), hsa-miR-139-5p (+2.36), and hsa-miR-1323 (+1.55) as upregulated, and hsa-miR-429 (−2.53), hsa-miR-141-3p (−1.79), and hsa-miR-1277-5p (−1.25) as downregulated post-NAC. The single patient achieving the lowest residual disease burden (P3, Luminal B, RCB-I, score 1.32) displayed a distinct pre-treatment miRNA profile, separating from all other pre-NAC specimens on principal component analysis and characterised by higher baseline hsa-miR-139-3p/-5p and lower baseline hsa-miR-429 and hsa-miR-141-3p expression, suggesting that baseline miRNA expression patterns may contribute to differential chemotherapy response. RCB score showed a non-significant positive trend with post-NAC Ki-67 (ρ = +0.71, p = 0.07). This pilot study identifies NAC-modulated candidate miRNAs in breast cancer and establishes a paired FFPE-based small-RNA-sequencing workflow applicable in routine clinical settings. The distinct pre-treatment profile of the single best responder generates the testable hypothesis that baseline expression of tumour suppressor miRNAs of the miR-139 family, together with low miR-200-family expression, may track chemosensitivity. As no candidate reached statistical significance after multiple testing correction and none has been validated in an independent cohort or by an orthogonal method, all findings are exploratory and hypothesis-generating. The results support larger prospective validation studies examining miRNA signatures as predictive biomarkers of NAC response across breast cancer molecular subtypes. Full article

Hydraulic fracturing in low-permeability porous rocks involves strong interactions between rock deformation, pore fluid transport, and progressive fracture damage. In this study, a hydro-mechanical phase-field model was developed to investigate hydraulic fracture evolution in saturated porous media. Biot poroelasticity, tensile–compressive strain energy decomposition, irreversible phase-field fracture evolution, and damage-dependent permeability were incorporated within a common finite element framework. The model was implemented in COMSOL Multiphysics 6.4 and used to examine the effects of the horizontal principal stress difference, injection rate, and fracturing fluid viscosity on the fracture morphology and pressure response. Within the investigated parameter ranges, increasing the horizontal principal stress difference from 2 to 14 MPa reduced the stimulated fracture area from 42,640 to 21,300 m² (50.0%) and the number of secondary branches from 12 to 5. Increasing the injection rate from 3 to 6 m³/min increased the stimulated fracture area from 35,771 to 44,138 m² (23.4%), the branch count from 6 to 11, and the breakdown pressure from 135.19 to 162.11 MPa (19.9%). Increasing the fluid viscosity from 1 to 100 mPa·s increased the stimulated fracture area from 35,771 to 48,722 m² (36.2%) and the breakdown pressure from 135.19 to 183.21 MPa (35.5%). The injection rate sensitivity was also compared with published granite hydraulic fracturing experiments, which demonstrated a positive increase in breakdown pressure with injection rate. This comparison was interpreted as trend-level physical consistency rather than direct material-specific validation because the experimental and numerical systems differed in their rock type, scale, stress state, temperature, and injection rate range. The results demonstrated systematic sensitivities of the hydraulic fracture geometry and pressure response within the investigated two-dimensional model configuration. Full article

The durability of prestressed spun-cast concrete poles is typically assessed on the basis of the nominal mix design parameters and the assumption of material homogeneity. However, the centrifugal spinning of fresh concrete mix results in an uneven distribution of its components throughout the wall thickness, which may affect the actual cement content in individual layers and consequently, the durability. As part of this study, the distribution of cement content in spun concrete poles was analysed using an experimental approach based on the analysis of hardened concrete composition. Samples were taken from various locations along the height of the pole and divided into layers across wall thickness. Cement content, aggregate distribution, porosity, and water absorption were determined using a combination of chemical and physical methods. The results indicate that although the average cement content meets the design requirements (minimum amount of cement exceeds 300 kg/m³), there are significant local variations, particularly in the inner and outer layers of the cross section. The inner layer is characterized by increased cement content and porosity, while the outer layer is characterized by a higher coarse aggregate content and reduced cement content. It was also observed that the spinning program used in the production of the poles resulted in a homogeneous concrete structure at the top of the pole, where the spinning radius is smallest, with no signs of delamination. However, delamination of the concrete structure was observed at lower sections of the pole. These results highlight the limitations of assuming homogeneous material properties in durability design and suggest that the actual performance of spun concrete elements may deviate from predictions based on the standards. The results have direct implications for assessing the durability of spun concrete poles used in exposure classes such as XC4 and XD1. Full article

Particle swarm optimization (PSO) is a widely used method for solving single-objective optimization problems. However, PSO suffers from diversity loss and premature convergence, leading to suboptimal performance in complex problems. To address these limitations, this paper introduces a novel self-adaptive multi-learning strategy PSO (SMLS-PSO) designed for real-parameter optimization tasks. SMLS-PSO integrates four distinct learning strategy-based PSO variants into a behavior pool and employs a new self-adaptive strategy selection mechanism. This mechanism dynamically chooses the most suitable learning strategy to update the velocities and positions of particles based on fitness information and payoff at different evolutionary stages. To enhance the performance of SMLS-PSO, three key improvements are incorporated: (1) a stagnation counter parameter to minimize wasted fitness evaluations; (2) a boundary symmetry mapping method to manage out-of-range searches; and (3) a Quasi-Newton local search operator to boost local exploitation capabilities. SMLS-PSO is first compared with four component PSO variants on 13 basic benchmark functions. Subsequently, SMLS-PSO is compared with eight state-of-the-art PSO variants on both 30D and 50D CEC2017 test suite problems. Experimental results indicate that SMLS-PSO statistically and significantly outperforms the compared algorithms on the majority of the test problems, showcasing its superior optimization capabilities. Finally, SMLS-PSO was applied to the optimization problem of UWB anchors layout, and it achieved a higher locatable space coverage rate and a better average HDOP value compared to the conventional layout scheme and other PSO variant optimization schemes. Full article

To address the mismatch between solid conveying efficiency and melting efficiency in grooved barrel single-screw extruders (SSEs), the effects of barrel groove and screw channel structural parameters on the melting start point and melting length were systematically investigated based on the groove-channel coupled melting (GCCM) theory. Three extruder configurations—smooth barrel, spiral-grooved IKV (Institut für Kunststoffverarbeitung), and GCCM—were designed and tested on a hydraulically driven clamshell barrel SSE platform with a screw diameter of 45 mm and a length-to-diameter ratio of 30:1. Low-density polyethylene (LDPE) grade 607 was used as the model material. The results demonstrate that increasing the barrel groove depth shifts both the melting start point and melting length downstream, whereas the groove width has negligible effects. A minimum melting start point is achieved at a groove pitch of 4D. At a screw speed of 30 r/min, the GCCM extruder equipped with a BARR barrier screw achieves a melting start point 24.0% earlier than the IKV extruder and a melting length shortened to 62.7% of the IKV value, representing reductions of 27–35% and 21–31% compared to reported barrier screw and Maddox screw melting lengths, respectively. The actual throughput reaches 93.7–95.7% of the theoretical solid conveying throughput, with specific energy consumption only 8.5% higher than the IKV extruder and throughput fluctuation reduced to 23.7%. Complete melting is achieved at a melting zone temperature of only 110 °C, confirming the dominant role of internal frictional heat. This study provides systematic experimental data and theoretical guidance for the structural optimization of grooved barrel SSEs. Full article

An analytical approach is developed for calculating a phase diffraction axicon with angularly variable spatial frequency that generates a prescribed light curve without iteratively solving an inverse design problem: the axicon frequency function is obtained directly from the polar equation of the target curve. When the axicon is combined with a lens, the intended curve is formed in the focal plane (Fraunhofer region), whereas in the Fresnel zone the intensity pattern is closely related to the curve’s evolute. We systematize this correspondence for rings, ellipses, spirals and polygonal curves, and derive analytical parameter bounds associated with the appearance of inflection points that qualitatively reshape both the evolute and the diffracted field (including hybrid curve–evolute patterns and “rose”-type contours). The qualitative outcome depends on the curve class/type. For a convex curve without inflections the expected curve is formed in in the far field (or in the focal plane), whereas the Fresnel intensity envelope follows the evolute. If the curve has peculiarities, especially inflection points with unbounded evolute branches, hybrid curve–evolute structure appears, and the focal pattern may itself resemble the evolute. For ellipses and polygonal families we analytically identify parameter intervals that mark this transition. The approach is verified experimentally for polygonal axicons, with attention to fabrication tolerances and to matching camera planes with the simulated propagation distances. Measured intensity distribution patterns agree with the corresponding simulations for both convex contours and curves that contain inflection points. The results are of fundamental interest and of practical value for optical trapping and laser surface structuring, where a compact phase element should deliver a controlled bright contour at a chosen working distance. Full article

Bolted flange joints are critical load-bearing connection components of complex mechanical equipment, whose service performance is dominated by the coupled evolution of bolt preload relaxation and interfacial stiffness degradation under long-term cyclic combined loads. Under cyclic transverse excitation, the contact interfaces experience successive full-stick, partial microslip and macroslip states, accompanied by embedding, creep and friction-induced wear, resulting in time-varying preload attenuation and the continuous degradation of joint mechanical properties. Distinguishing preload relaxation without nut rotation from rotational self-loosening is essential for revealing multi-bolt flange degradation mechanisms. This paper presents a systematic review of physics-driven constitutive modeling and degradation characterization of bolted flange connections. A unified classification framework for joint interface models is established, covering static friction models; velocity-dependent dynamic friction models; hysteresis stick–slip models, represented by the four-parameter Iwan model and Valanis endochronic model; and reduced-order equivalent joint models. The inherent differences between the Dahl model and LuGre model regarding the Stribeck velocity–friction characteristics are clarified. The representative models are comprehensively evaluated from the perspectives of physical interpretability, hysteresis reproduction accuracy, preload–degradation correlation and engineering applicability. A further comparative analysis is conducted of parameter identification bottlenecks of the Iwan, LuGre and Valanis models, focusing on multi-solution risk, anti-noise robustness and cross-working-condition transferability. Compared with single-bolt lap specimens, multi-bolt annular flanges exhibit prominent inter-bolt elastic interaction, circumferential contact pressure non-uniformity and local-to-global chain-reaction degradation behaviors. The common experimental test-beds and sensing techniques for joint degradation monitoring are summarized, and the measurement limitations, including sensor drift, synchronization error and installation constraints, and their influences on model parameter identification, are discussed. The existing machine-learning, digital-twin and physics-informed modeling applications for bolted joints are briefly outlined. Finally, this review summarizes the existing research consensus, unresolved contradictions and open research challenges. Special attention is paid to the limitations of existing time-variant Iwan-type models for multi-bolt flange degradation. Potential future research directions include multi-channel synchronous sensing matching time-varying constitutive models, quantification of inter-bolt load redistribution, and robust identification strategies under noisy experimental data. Full article

To address the limitations of the original Honey Badger Algorithm (HBA), including premature convergence, limited search directionality, and insufficient local escape capability in high-dimensional complex optimization problems, this paper proposes an improved Honey Badger Algorithm based on a traffic-driven strategy, namely the Traffic-driven Covariance Honey Badger Algorithm (TCHBA). The proposed algorithm introduces three synergistic evolutionary mechanisms. First, Elite Covariance Rotation Guidance learns correlated search directions from the current elite subset and injects a truncated covariance-based step into the HBA update. Second, Urban Traffic-Inspired Search uses population density and an iteration-dependent signal to regulate attraction and diversion. Third, Stagnation-Aware Lens Opposition Mutation is activated after unsuccessful updates and combines lens opposition with a heavy-tailed Cauchy perturbation to restore search mobility. Extensive experiments are conducted on the CEC2017 (100-dimensional) and CEC2022 (10- and 20-dimensional) benchmark suites. The results demonstrate that TCHBA significantly outperforms nine state-of-the-art optimization algorithms, including VPPSO, EGWO, GJO, RIME, ALA, HBO, MO, PWO, and the original HBA, in terms of solution accuracy, convergence speed, and statistical robustness. Furthermore, TCHBA is applied to the problem of Taiwanese enterprise bankruptcy prediction, a representative financial risk classification task. By optimizing the key parameters of the K-nearest neighbors (KNN) classifier, a TCHBA-KNN prediction model is constructed. Experimental results on real-world datasets show that the proposed model achieves superior performance in terms of accuracy, Matthews correlation coefficient (MCC), recall, and F1-score, thereby validating the effectiveness and practical potential of the proposed algorithm for real-world engineering and financial decision-making problems. Full article

To address the issues of excessive fault current, insufficient voltage support, and frequency oscillations in grid-forming converters during power grid short-circuit faults, this paper establishes a fault ride-through test model based on the principle of impedance voltage division and analyzes the fault transient characteristics of a virtual synchronous generator (VSG). A fault-voltage support strategy integrating reactive power injection and internal electromotive force (EMF) regulation, together with an active power regulation method based on current-limiting constraints, is proposed. An adaptive inertia-damping mechanism is introduced into the control loop, which dynamically regulates the virtual inertia and virtual damping coefficients to suppress frequency fluctuations during fault engagement and clearance. The rationality of the system parameter configuration is verified through impedance modeling, and experimental validation is conducted using the RT-LAB hardware-in-the-loop (HIL) platform. The results demonstrate that the proposed multi-objective coordinated control strategy enables the converter to remain connected to the grid during faults. The steady-state fault current meets the limit requirements, the frequency response is stable, and reactive power support complies with the national standard. This study provides theoretical support for fault ride-through of grid-forming converters in power systems with a high proportion of power electronics. Full article