Search Results (61,086)

To address the high deployment cost, insufficient local coverage, and limited timeliness of conventional wave-observation methods in onboard real-time applications, this study conducts a comparative investigation of centre-of-gravity-equivalent instantaneous wave-height estimation models based on three-degree-of-freedom ship motion responses under the framework of the wave buoy analogy (WBA). The heave, roll, and pitch responses of a 1:2 scaled Series 62 4667-1 planing craft model in regular head seas are used as inputs, while the synchronous instantaneous wave-height signal measured by a wave probe near the centre of gravity is used as the label. A unified protocol is established with consistent inputs, labels, window construction, data partitioning, and evaluation metrics. Six models, namely SVR, TCN, LSTM, CNN-LSTM, Transformer, and LSTM-MHA, are compared and validated using STAR-CCM+ numerical simulation data and towing-tank experimental data. The results indicate that, in the simulated case of H = 0.10 m and T = 1.5 s, LSTM-MHA achieves the highest estimation accuracy, with RMSE and R² values of 0.001231 and 0.997848, respectively, but it also has the largest model size and computational cost. In comparison, TCN achieves near-optimal accuracy with a smaller parameter count and lower inference latency, and shows stable performance across multiple conditions. The towing-tank experimental results further show that both LSTM-MHA and TCN clearly outperform the SVR baseline. Overall, accuracy in the simulation domain, robustness in the towing-tank experimental domain, and cross-domain generalisation capability are not fully consistent. Therefore, the selection of onboard instantaneous wave-height estimation models should jointly consider estimation error, model complexity, computational latency, window length, and practical deployment requirements. Full article

Online apparel size recommendation remains difficult because consumers cannot physically assess garment fit before purchase. It is a multi-dimensional fit evaluation problem, particularly for complex garments such as jackets, where multiple body areas jointly influence perceived fit. Existing methods often rely on limited anthropometric measures, heuristic rules, or behavioral data, restricting both accuracy and interpretability. To address this issue, this study proposes an interpretable multi-dimensional fit evaluation framework based on garment ease theory. The framework defines ideal ease as the target fit condition and quantifies deviations through a segment-based weighting mechanism. Section-level mappings between body and garment measurements are established, and differentiated penalties are assigned according to the semantic fit interval of each body area. Section-specific evaluations are aggregated into an overall fit score (OFS) for candidate size ranking and Top-K recommendation, while also providing detailed fit feedback. Experiments involving 270 female participants and two jacket styles show high recommendation accuracy, achieving Top-3 accuracies of 99.6% for the regular-fit jacket and 98.9% for the tight-fit jacket. Compared with traditional heuristic methods, the proposed approach demonstrates clear advantages in both performance and interpretability, offering a practical solution that balances accuracy, transparency, and deployability. Full article

Three-dimensional UAV operations require path planning methods that can jointly maintain route efficiency, threat avoidance, and trajectory smoothness under spatially distributed and time-varying constraints. To address this problem, this paper develops an integrated Dual-Layer Adaptive T-perturbation and Opposition-based Multi-Objective Particle Swarm Optimization framework, termed DATO-MOPSO, for 3D UAV path planning in complex threat environments. The method integrates a dual-layer adaptive inertia-weight and velocity-regulation mechanism with symmetric T-perturbation, an elite quasi-opposition-based learning strategy for diversity recovery and feasible local exploitation, and an archive-driven simulated annealing rule for stagnation-aware personal-best updating. A three-objective model minimizing path length, threat exposure, and path smoothness is established, and comparative experiments against MOPSO, ZAMOPSO, NSGA-II, and SPEA2 are conducted in both static and dynamic environments, together with statistical and ablation analyses. In the static scenario, DATO-MOPSO achieved the highest mean HV and stable repeated-run performance, but its IGD was comparable to ZAMOPSO with higher computational cost. In the dynamic scenario, DATO-MOPSO showed its main advantage, achieving the highest mean HV and the lowest mean IGD with statistically significant HV and IGD improvements over all baselines. Overall, DATO-MOPSO is most advantageous in time-varying complex threat environments, whereas its static-scenario advantages are accompanied by higher computational cost. Full article

This study presents an approach to quantifying impact-induced damage severity in composites, focusing on synthetic carbon fibre-reinforced polymer (CFRP), natural flax fibre-reinforced polymer (FFRP) and hybrid fibre reinforced polymer (HFRP) composite of carbon and flax. The investigation aims to quantitatively characterise impact damage under energies ranging from 10 to 70 J through acousto–ultrasonics (AU) testing, proposing an efficient technique for evaluating the integrity of various FRP composites under in-service conditions. AU testing was performed at azimuthal angles of 0°, 30°, 45°, 60° and 90°, utilising acousto–ultrasonic waveform indices (AUWIs), such as wave velocity, peak amplitude, energy content, centroid frequency and skewness factor. The damage severity index is correlated with the damage mode. The findings establish that wave velocity is a reliable parameter for quantifying damage severity across all composite material types considered, with high adjusted R² values of 0.92 for CFRP, 0.89 for FFRP and 0.90 for HFRP. Peak amplitude also shows considerable sensitivity. Finally, this research highlights the limitations of traditional non-destructive evaluation (NDE) techniques and demonstrates the potential of combining multi-damage metrics with advanced imaging methods, such as X-ray micro-computed tomography (X-ray µCT) and scanning electron microscopy (SEM), to provide a comprehensive assessment of damage in various composite materials. The proposed methodology offers a promising approach for quantifying the impact damage severity in composite structures, as applicable to wind turbine blades, amongst other structural components. Full article

We investigate the onset of hyperbolicity in Jensen polynomials $J_{d,n}$ associated with the Riemann $\Xi$-function and identify a robust parity-driven bifurcation with a natural geometric interpretation. Numerical analysis for degrees $5\le d\le 16$ reveals two distinct regimes. For even d, the roots form a compact complex cluster whose imaginary extent decreases smoothly, and the transition to hyperbolicity is governed by a single complex-conjugate pair, consistent with a low-dimensional (tame) geometric structure. For odd d, a hierarchy of more intricate onset mechanisms emerges, including single-event transitions ($d=11$) and intermittent regimes ($d\ge 13$) with decoupled geometric invariants, suggestive of dynamics on decorated (wild) character varieties. We interpret this dichotomy through a connection with the $P_{\mathrm{III}}\left(D_6\right)$ tau-function arising in the Painlevé confluence diagram. Defining $\tau \left(t\right)=\Xi ({\displaystyle \frac{1}{2}}+\sqrt{-t})/\Xi \left({\displaystyle \frac{1}{2}}\right)$, we construct a generating function $B\left(w\right)={\sum }_{j\ge 0}{b}_j{w}^j$ from the cumulants of $log\Xi ({\displaystyle \frac{1}{2}}+z)$ using high-precision Cauchy/DFT methods (280–400-digit arithmetic), without explicit use of the zero expansion. Two independent numerical diagnostics indicate that B exhibits Stieltjes-type behavior: (i) positivity of Hankel determinants up to order $N=30$ and (ii) Padé approximants whose poles converge to ${\gamma }_k^2$ (squares of Riemann-zero ordinates) with stabilizing residues. These results provide strong evidence that the parity bifurcation observed in Jensen polynomial onset reflects a finite-dimensional manifestation of an underlying moment-based positivity structure. Motivated by this correspondence, we formulate a conjecture relating the Stieltjes nature of $B\left(w\right)$ to the eventual hyperbolicity of Jensen polynomials. This conjecture suggests a bridge between finite-dimensional root geometry and an infinite-dimensional kernel-based positivity framework, while leaving open the problem of establishing such positivity independently of the zero expansion. Full article

In the context of a constantly deteriorating environmental situation, in particular due to the uncontrolled accumulation of plastic waste, the search for effective ways to recycle plastic is an urgent task. Pyrolysis of plastic waste followed by the hydrosaturation of liquid products may become a promising method for obtaining components of motor gasoline. The aim of this study is to obtain motor gasoline components from plastic waste through pyrolysis, followed by hydrogenation of the fuel fractions for their use in the production of commercial fuels. The scientific novelty of this study consists of establishing the influence of hydrosaturation process parameters on an Al-Co-Mo hydrotreating catalyst (temperature and feedstock flow rate) on the transformation of hydrocarbons present in the gasoline fraction separated from the liquid pyrolysis products of polypropylene waste. The most preferred conditions for obtaining feedstock for subsequent hydrosaturation of polypropylene waste turned out to be the pyrolysis process carried out at a temperature of 450 °C and atmospheric pressure. Based on calculations in the Compounding software, promising blending components were identified. Based on the obtained results, two samples were identified as having the greatest potential for blending commercial gasolines in terms of hydrocarbon composition and performance characteristics. The sample obtained at the hydrosaturation process parameters of 350 °C and a feedstock flow rate of 0.51 mL/min is the most preferable in terms of its composition, since it demonstrates a minimal content of olefins (18.7 % vol.) and benzene (0.87 % vol.) but has a relatively low octane number (RON 58.7). The sample obtained at the hydrosaturation process parameters of 300 °C and a feedstock flow rate of 0.85 mL/min has relatively higher octane characteristics (RON 72.9) and can be used as a high-octane component but requires blending with components that compensate for the increased olefin content. Also, it is shown in this work that hydrosaturation of the gasoline fraction separated from the liquid pyrolysis products of polypropylene waste enables the production of motor gasoline components whose blending rate in commercial gasolines recipes can reach up to 35 % by volume. Full article

Group Relative Policy Optimization (GRPO) streamlines the alignment of Large Language Models (LLMs) and Vision–Language Models (VLMs) by eliminating the Critic model. However, its efficiency heavily depends on the group size, G. While a larger G improves reward estimation and stabilizes the Advantage, $A_i$, it drastically increases VRAM usage and reduces throughput. Standard heuristics like a fixed G of 64 create significant bottlenecks in resource-constrained settings. This paper introduces an Efficiency-Aware optimization framework utilizing Multi-fidelity Bayesian Optimization and Hyperband (BOHB) to dynamically identify the optimal group size, $G^{*}$. The method uses a multi-objective function that balances reward accuracy, $A_i$ variance, and hardware utilization, applying z-score normalization. By employing Successive Halving to quickly evaluate candidates at low fidelity, the framework reduces search costs by up to 74% compared with random search. Tested across text-only LLMs (Qwen2.5-7B/1.5B) and multimodal VLMs (Qwen2.5-VL-3B), the framework demonstrates that the discovered $G^{*}$ saves up to 72.5% in VRAM compared with the baseline of 64, while maintaining reward accuracy within 5.8%. Sensitivity analyses on hyperparameters like $\lambda$, $\alpha$, and $\beta$ confirm the framework’s robustness. Rather than treating group size as a mere engineering heuristic, this study establishes a principled methodological advance by formalizing the trade-off between statistical estimation stability and hardware constraints into a unified optimization framework for resource-efficient RLHF. Full article

The escalating security risks associated with unauthorized unmanned aerial vehicles (UAVs) in advancing smart cities necessitate the development of robust active countermeasures. This work presents a novel approach centered on a UAV-borne flexible net system and provides a rigorous investigation into its complex nonlinear dynamics. This study establishes a lumped-mass, semi-spring–damper dynamic model of the flexible capture net, characterizing its key dynamic properties, including deployment performance, aerodynamic attitude, and the high-impact phenomena of collision and entanglement with the target UAV. To verify the reliability of the proposed method, numerical simulations are combined with field tests for systematic validation. Comparative analysis reveals excellent quantitative agreement, with over 80% conformity in the net’s spatial configuration between simulated and experimental results. This paper illuminates the fundamental principles governing energy dissipation and transient tension dynamics pre- and post-capture. This study provides preliminary evidence for the feasibility of the proposed method and identifies key directions for future investigation. The findings offer guidance for the design and optimization of future systems intended to neutralize low, slow, and small (LSS) aerial threats. Full article

Words occurring in similar contexts have been observed to have similar meanings. A natural and established method within computational linguistics implements this observation by representing words as vectors with dimensions determined by words that are witnessed in fixed positions in relation to the target word. We generalize this context vector approach to part-of-speech (POS) sequences appropriate to word sequences. As with words, the context of a POS tag (considering the POS tags occurring before and after any target tag) reflects its syntactic constraints and may approximate the “meaning'' of the target tag, from a distributional perspective. We use the 111-million-word British National Corpus (BNC) and the sequence of POS labels lifted from those texts to calculate POS context vectors. We observed significant agreement between the clusters of POS context vectors and the supercategories of corresponding POS tags, and examined potential categorization of the POS categories that emerged from the vector clusters. We also found that though vector measures partially align with the predictions of generativist linguistic theories, the approach suggests a more complex relation between syntactic categories. We conclude that a mutual-information-based approach better approximates the distributional “meaning'' of syntactic categories than the conditional probability distribution of POS symbols. Full article

Emissivity is a parameter allowing the assessment of thermal/optical properties of active pharmaceutical ingredients (APIs). ε reflects radiative properties, changes with product aging, and correlates with surface characteristics. This study analyzed the thermal emissivity of commercial tablets—extended-release tablets with metformin hydrochloride (from two manufacturers: XR I and XR II), coated (Co) tablets with ibuprofen, and chewable (Ch) tablets with sodium aluminum dihydroxycarbonate—and compared unexpired vs. expired products. We used the ET 100 emissometer (Surface Optics Corporation, USA; IR range 1.5–21 µm) to measure directional–hemispherical reflectance (DHR) at 300 K, and on the basis of these values, directional thermal emissivity at 20° (DTE20) and 60° (DTE60) and hemispherical thermal emissivity (HTE) were calculated. Then, emissivity parameters were evaluated at 500 K, 800 K, and 1200 K. The DHR values at a 60° angle differed between unexpired and expired XR II tablets across all spectral bands and for XR I tablets, except in the 3.0–4.0 micron range. In turn, for DHR at 20°, high effect sizes were demonstrated between unexpired and expired Ch tablets for 1.5–2.0, 2.0–3.5, 4.0–5.0, and 5.0–10.5 microns. For the DHR at 60°, the high effect size between unexpired and expired Ch tablets was found at 1.5–2.0, 2.0–3.5, and 4.0–5.0 microns. At 300 K, XR I and XR II tablets showed comparable DTE20, DTE60, and HTE. The Ch tablets had higher DTE20 than XR I and XR II (0.968 vs. 0.954 and 0.958, respectively; p < 0.001) and Co tablets (0.968 vs. 0.930; p < 0.001). The Co tablets had the highest DTE60 mean values (0.941 vs. 0.926 for Ch, p < 0.001; 0.926 for XR I, p < 0.001; 0.932 for XR II, p = 0.001). The HTE value was the highest for Ch tablets (p < 0.001 vs. others). During thermal modeling of the emissivity parameters, all DTE20, DTE60, and HTE values decreased with temperature, reaching their lowest values at 1200 K. The largest relative decrease in HTE values (over 15%) between the standard measurement temperature of 300 K and the modeled temperature of 1200 K was found for Ch tablets. Tablets with different release profiles show distinct DTE20, DTE60, and HTE values, suggesting that emissivity may serve as a rapid, non-destructive screening tool that could support further pharmaceutical evaluation during storage. However, emissivity alone does not establish pharmaceutical quality, and the present findings should be interpreted as proof-of-concept rather than as validation of a stand-alone quality-control method. Full article

Background: Heart failure (HF) is a major public health problem and a paradigmatic condition for sex differences in cardiovascular disease. However, national population-based evidence describing these differences remains limited. We aimed to provide the first nationwide sex-stratified epidemiologic characterization of HF in Spain, quantifying incidence, prevalence, and clinical characteristics across age groups and left ventricular ejection fraction (LVEF) categories. Methods: We conducted a retrospective population-based study using the BIG-PAC database, integrating electronic health records from primary and hospital care covering approximately 1.8 million individuals across seven Spanish autonomous communities. Adult patients with incident HF between 2013 and 2019 were identified. HF phenotypes were classified according to LVEF as reduced (HFrEF ≤40%), mildly reduced (HFmrEF 41–49%), preserved (HFpEF ≥50%), or unknown (HFuEF). Incidence rates per 1000 person-years and prevalence were estimated and stratified by sex and LVEF phenotype. Results: In total, 19,961 incident HF cases were identified. Overall HF incidence was 3.23 per 1000 person-years and was similar in women and men (p = 0.697). HF prevalence was 2.34% and higher in men than in women (2.67% vs. 2.06%; p < 0.001). Women were older and more frequently presented with HFpEF (38%), whereas HFrEF predominated in men (53%); notably, HFrEF still accounted for approximately one third of HF cases among women. Once stratified by LVEF phenotype, clinical characteristics were broadly similar between sexes. Conclusions: While HF incidence was similar in women and men, substantial sex differences in prevalence, age, and phenotype distribution were identified, establishing the first nationwide epidemiological framework to inform sex-aware HF prevention and healthcare planning in Spain. Full article

Background: Physical activity is a well-established modifiable lifestyle factor associated with reduced cancer risk; however, the optimal weekly volume of moderate-to-vigorous physical activity (MVPA) for cancer prevention, particularly when assessed using objective measures, remains unclear. Most existing evidence relies on self-reported physical activity, which may introduce measurement bias and obscure accurate dose–response relationships. Methods: We analyzed data from UK Biobank participants with valid accelerometer measurements to quantify habitual MVPA. Observational associations between MVPA and incident cancer were evaluated using multivariable Cox proportional hazards regression and restricted cubic splines. One-sample Mendelian randomization (MR) analyses, including both linear and nonlinear approaches, were conducted to evaluate potential causal associations and explore possible dose–response patterns. Results: Higher MVPA was associated with lower total cancer risk (HR 0.971, 95% CI 0.954–0.988, p = 0.001). Consistent associations were observed for several site-specific cancers, particularly lung, colorectal, breast, kidney, and bladder cancer. MR analyses supported a directionally consistent association between genetically predicted MVPA and lower total cancer risk (HR 0.977, 95% CI 0.962–0.992, p = 0.002). Nonlinear MR analyses suggested a potential nonlinear association, with lower cancer risk observed at a model-derived exploratory point of approximately 5 h of weekly MVPA. Conclusions: These findings provide supportive evidence that higher accelerometer-measured MVPA is associated with lower total cancer risk and contribute to a better understanding of the dose–response relationship between MVPA and cancer incidence. Full article

Background: During intense bouts of physical activity, the body of athletes is subjected to stress and sometimes this can lead to adverse events such as injuries or more severe organ dysfunction, like sudden cardiac death. Several markers are being studied to properly assess the level of physical stress that exercises have on the body and one of them is amylase. Methods: We evaluated 19 licensed football players using basic cardiovascular procedures, i.e., resting 12-lead electrocardiogram (ECG) and trans-thoracic echocardiography (TTE) and performing a cardiopulmonary exercise testing (CPET). Resting (T0) serum and salivary amylase levels were measured, as were immediately post-effort (T1) serum values and 10 min (T2) and 30 min post-CPET (T3) salivary values. Results: Both serum and salivary levels showed correlations with several TTE and CPET parameters. Only T2 salivary amylase levels did not show any correlations with the other parameters, while also no correlations could be established between serum and salivary determinations. Conclusions: Serum and salivary amylase determinations show potential in athlete evaluation even from a cardiovascular risk standpoint since they displayed several correlations with both TTE and CPET parameters, but as part of a more complex protocol. Salivary determinations cannot fully substitute serum measurements. Further studies on larger groups are required. Full article

Multi-criteria group decision making (MCGDM) under linguistic uncertainty remains a fundamental challenge in applied mathematics, where decision makers seldom assign crisp numerical evaluations and frequently exhibit heterogeneous risk attitudes shaped by behavioural factors. An integrated mathematical framework, hereafter PLR-3WBC (Probabilistic Linguistic Regret-driven Three-Way Bayesian Consensus), is developed to systematically integrate four methodological components that have each been individually validated in the MCGDM literature: representation of decision information with explicit probability mass on linguistic terms; quantification of decision-maker regret and rejoice psychology under linguistic uncertainty; classification of alternatives into three actionable decision regions rather than a single-valued ranking; and group consensus reaching with credal weight aggregation. Each component has demonstrated its effectiveness in its respective domain; the present framework capitalises on their complementary strengths by embedding them within a single pipeline equipped with formal guarantees, an integration that has not been previously reported. The framework integrates five methodological components: probabilistic linguistic term sets (PLTS) for information representation; the Bayesian best–worst method (BBWM) for credal criterion weighting; a regret–rejoice value function adapted to the linguistic domain for behavioural evaluation; three-way decision (3WD) thresholds derived from a loss-function model for actionable classification; and a distance-based consensus reaching process with feedback mechanism for group convergence. A case study on age-friendliness evaluation of twelve aging urban residential communities under an indicator system of five dimensions and eighteen criteria, with four expert decision makers, demonstrates that PLR-3WBC delivers an actionable three-way classification, recovers a transparent group consensus, and produces rankings broadly consistent with classical TOPSIS, VIKOR, PROMETHEE-II, and BWM-TOPSIS (Spearman rank correlation exceeding 0.97), thereby confirming that the integrated framework preserves the ordinal reliability of these established methods, while additionally delivering three outputs that arise from the methodological integration: an actionable three-way classification enabling discrete budget-aligned decisions, credal weight intervals quantifying the depth of expert agreement on criterion importance, and a behavioural reordering of borderline non-dominated alternatives that reflects the loss-averse psychology of the decision panel and would remain hidden under single-method deployment. Sensitivity analyses with respect to the regret aversion coefficient, the loss function parameters, and the consensus threshold confirm that the qualitative classification is stable across a wide parameter envelope, supporting the practical deployment of PLR-3WBC in age-friendly community renewal programmes. Full article

Copper azides are promising energetic materials for miniaturized pyrotechnic devices and micro explosive trains owing to their short detonation growth distance and high initiation energy. However, controllable preparation of copper nanoparticle precursors and their in situ conversion to copper azides under mild conditions remains challenging. In this study, copper nanoparticles were synthesized via a coordination-assisted aqueous reduction method at room temperature under air atmosphere using nitrilotriacetic acid disodium salt (NTA·H·2Na) as the complexing agent. The resulting nanoparticles were pressed into polyester rings to construct confined precursor structures, and copper azide micro-charges were prepared through in situ gas–solid reaction with HN₃ gas generated from NaN₃ and concentrated phosphoric acid at 60 °C. SEM characterization revealed that the morphological evolution of copper azides followed a three-stage pattern: “product island nucleation, branch/block coalescence growth, and continuous product layer formation and structural reconstruction”. Detonation velocity tests using the electrical probe method showed an average value of (5.10 ± 0.07) × 10³ m/s. Flyer impact initiation tests demonstrated that, with a charge thickness of 1.00 mm, both a 30 μm polyimide flyer and a 40 μm titanium flyer could successfully initiate a HNS–IV explosive. The preparation methodology and performance characterization established in this work provide an experimental basis for the application of copper azides in micro-initiation systems. Full article