Search Results (22,470)

Volumetric additive manufacturing (VAM) enables layerless and fast printing within seconds. However, print quality remains highly sensitive to the delivered energy. In this study, the effects of visible (460 nm) and ultraviolet (385 nm) projector power were evaluated in a dual-color VAM setup with a CQ/EDAB initiated TEGDMA/BisGMA resin with an o-Cl-HABI inhibitor. Cubes ($6\times 6\times 6.7 {\mathrm{mm}}^3$) were printed under controlled visible and ultraviolet power and exposure times, then evaluated using in situ shadowgraphy, three-dimensional metrology, and confocal microscopy. Higher visible power reduced the polymerization initiation time, but increasing the visible dose rapidly led to over-polymerization, resulting in dimensional growth, corner rounding, and increased surface roughness ($R_a$). The lowest lateral variation was observed at the shortest exposure times, with a maximum error of 1.8%. Ultraviolet illumination did not significantly change initiation time or reduce over-polymerization within the tested intensities and inhibitor concentration ranges. Surface evaluations revealed a periodic line texture with a pattern pitch of approximately 25 μm. By shifting the focal plane and using a low-resolution projector, the pattern pitch increased to about 150 μm. These values were aligned with the ${\mathrm{MTF}}_{50}$ spatial frequencies of each projector at different defocus positions. This study provides useful guidelines for adjusting intensity to achieve high-fidelity VAM printed parts. Full article

Public transport is vital for social and economic life, but many people with disabilities still face exclusion due to both physical and psychosocial barriers. This study examined how psychosocial barriers influence public transport travel behavior among people with mobility, vision, and hearing disabilities in the City of Tshwane, South Africa. A quantitative survey was conducted using a structured questionnaire among 214 respondents. The results showed that fear of crime, lack of personal safety, anxiety when travelling alone or to unfamiliar places, and negative treatment by drivers and co-passengers are major deterrents to public transport use. Psychosocial barriers were significantly associated with travel behavior and a strong preference for private cars as well as ride-hailing services. Group comparisons revealed that individuals with vision disabilities experience significantly higher levels of transport-related fear compared to other groups. People with mobility and vision disabilities are more affected by negative attitudes from co-passengers compared to people with hearing disabilities. Psychosocial barriers are associated with low trip frequencies for non-essential activities, indicating suppressed travel. The study concludes that achieving inclusive urban mobility requires addressing psychosocial barriers alongside physical accessibility to ensure safe, dignified, and independent travel for people with disabilities. Full article

One of the strongest electromagnetic engineering approaches for enhancing antenna performance is the use of photonic crystal (PhC) substrates. This technique can be efficiently applied to antenna design and offers notable advantages, such as gain improvement, increased bandwidth, and frequency-dependent beam scanning. In this paper, a bow-tie dipole antenna has been developed for terahertz operation over the 0.39–1.3 THz band, presenting a novel structure capable of producing strong ultra-wideband (UWB) field enhancement within its feed gap. The feed gap between the two metallic arms has a slot width of 1.24 λ0 (λ0 is the wavelength in free space at a center range of 0.8 THz), which facilitates the generation of an enhanced electric field. The PhC substrate enables surface-wave control through dispersion engineering, thereby enhancing the radiation efficiency of the antenna. The proposed antenna exhibits a radiation efficiency of approximately 73–93% over the entire UWB frequency band. Furthermore, the PhC substrate antenna achieves a maximum gain of 21 dB, exceeding that of a homogeneous-substrate THz bow-tie antenna by at least 3.3 dB. The results indicate that the antenna achieves |S₁₁| < −10 dB impedance matching over the bandwidth of 105.9%, ranging from 0.4 to 1.3 THz. The proposed bow-tie dipole antenna integrated with a PhC substrate demonstrates a wide beam-scanning capability from −54° to +74° across the 0.39–1.16 THz band, while maintaining a compact footprint of 14.9 λ₀ × 22.4 λ₀. This combination of wide scanning, broad bandwidth, and ultra-low profile represents a notable advancement in the development of compact THz radiating structures. Full article

High penetration of renewable energy sources (RESs) introduces significant power fluctuations, threatening voltage and frequency stability in modern power systems. This paper presents an integrated framework for static voltage stability assessment and stability-constrained optimization of under-frequency load shedding (UFLS) in renewable-dominated grids. A low-conservativeness analytical criterion is first derived for static voltage stability margin assessment. Then, a hybrid Deep Belief Network–Long Short-Term Memory (DBN–LSTM) model is developed for accurate renewable power forecasting, capturing temporal variability and uncertainty. Finally, UFLS-based stability-constrained dispatch is formulated to prevent voltage collapse, enhance the system stability, and minimize RES curtailment. Simulations on a modified IEEE benchmark system demonstrate that the proposed approach improves voltage and frequency stability while maintaining high renewable energy utilization. Full article

To overcome the intrinsic trade-off among miniaturization, ultrawideband (UWB) performance, and structural simplicity in conventional frequency-selective rasorber (FSR) design, this paper proposes a miniaturized UWB absorption–transmission–absorption (A-T-A) FSR based on an inter-cell current-interaction mechanism. The structure comprises a dielectric matching layer (DML), a lossy frequency-selective surface (FSS), a lossless FSS layer, and air/dielectric spacers. Both FSS layers are fabricated on Rogers 4350B substrates without any metallized via or multiple lossy/lossless FSS stacking. The proposed FSR achieves a miniaturized structure with dimensions of 0.085 λ_L × 0.085 λ_L × 0.118 λ_L (where λ_L corresponds to the wavelength at the lowest absorption frequency). A fractional operational bandwidth around 144% is obtained, covering 2.88–12.87 GHz and 14.98–17.61 GHz with absorptivity over 80%, together with a low-loss transmission band of 13.57–14.56 GHz exhibiting a minimum insertion loss of 0.41 dB. As the incident angle increases up to 40°, the FSR retains more than 134% bandwidth for both TE and TM polarizations. A prototype was fabricated and measured, and the results agree well with the simulations. Full article

Energy harvesting has emerged as a promising solution for powering aircraft structural health monitoring (SHM) systems by exploiting ambient vibration energy. This work presents a novel clustered piezoelectric energy harvester (CPEH) designed to enable autonomous sensing and wireless data transmission in aircraft structures. Aircraft sections experience complex, multiple vibration modes during flight; however, the proposed harvester is specifically designed to exploit the oscillatory motion of the vertical tail unit (VTU) of a VUT-100 Cobra aircraft during the cruise phase. The energy harvester employs a clustered piezoelectric cantilever configuration incorporating magnetic stiffness nonlinearity, which enhances vibration-induced strain and enables effective frequency tuning. The nonlinear magnetic interaction broadens the operational bandwidth and improves energy conversion performance under low excitation amplitudes. The system is tuned to operate over a broadband frequency range of 110–130 Hz, with optimal performance achieved at acceleration amplitudes of less than 0.5 g, corresponding to the measured VTU vibration levels during the cruise phase of the flight. An experimental prototype was tested in the laboratory under aircraft cruise-phase vibration conditions, successfully achieving maximum power of 0.041 mW at optimum resistance of 390 KΩ and 5.45 mJ of stored energy in a 1000 µF capacitor within 10 min, confirming the feasibility of the proposed harvester for aircraft SHM applications. Full article

Background: Fermented dairy foods, such as yogurt and cheese, contain bioactive components that differ from those in non-dairy foods, but their associations with depression and dementia risk in later life remain unclear. Methods: We analyzed data from the Sydney Memory and Ageing Study, a community-dwelling cohort of adults aged 70–90 years, to examine associations between dairy intake and depressive symptoms (Geriatric Depression Scale-15), psychological distress (Kessler-10), and incident depression (physician diagnosis or antidepressant use) and dementia (DSM-IV criteria). Intake of yogurt, cheese, and non-fermented milk was assessed at baseline using a validated food-frequency questionnaire. Longitudinal associations were examined using Fine–Gray competing-risks models that accounted for death; cross-sectional associations were also assessed. Results: Among 966 participants (mean age: 78.3; 55.5% women), compared with no consumption, higher yogurt intake (one standard serving) was significantly associated with lower depressive symptom scores (adjusted β: −0.37 and −0.39 for quartiles 3–4 (mean: 88.5–164 g/day), and so was low-fat cheese intake (mean: 13.2 g/day) (adjusted β: −0.35). Over a mean follow-up of 3.3 years, 120 incident cases of depression and 68 deaths occurred: higher yogurt intake and low-fat cheese consumption (versus non-consumption) were associated with lower risk of depression (adjusted subdistribution hazard ratios 0.41 [95% CI 0.19–0.88] and 0.40 [0.21–0.78], respectively). No significant associations were observed for psychological distress, cognition, or incident dementia (a mean follow-up of 5.2 years, 100 incident cases, and 153 deaths); no associations were observed for regular cheese or milk intake. Conclusions: These findings suggest a potential role for fermented dairy foods, particularly yogurt and low-fat cheese intake, but not non-fermented milk, in mental well-being in later life. Full article

The development of high-performance polymers exhibiting both low dielectric constant (D_k) and low dielectric loss (D_f) at high frequencies is highly desirable yet challenging for applications in microelectronics and wireless communication technologies. In this work, a series of siloxane-containing poly(ester imide)s (SiPEIs) are designed and synthesized via a two-step polymerization route, using 1,4-phenylene bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHQ) as the dianhydride monomer, and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (DMS) together with 4,4′-diaminodiphenyl ether (ODA) as the diamine comonomers. Although the introduction of short siloxane segments lowers the glass transition temperature (T_g) and the tensile strength of the resulting PEIs, they still remain at a relatively high level. Liquid crystalline phase behavior is observed at lower temperature for the siloxane-containing PEIs. Meanwhile, the hydrophobicity and the high-frequency dielectric performance is effectively improved with increasing siloxane content. Notably, SiPEI-20, prepared with 20 mol% DMS, displays an outstanding integrated performance. It exhibits a T_g of 200 °C, a D_k of 2.87 and a D_f of 0.00155 at 10 GHz, as well as an adhesive strength of 0.85 N·mm⁻¹ on copper foil. Overall, this work provides a feasible strategy by incorporating siloxane into the PEI backbone, enabling the synergistic enhancement of high-frequency dielectric properties (simultaneous reduction in D_k and D_f) and adhesion to copper foil. Full article

Against the backdrop of increasing global emphasis on sustainable development and ecological conservation, green seafood has emerged as a key component of sustainable marine food consumption. However, the discrepancy between consumers’ intention to consume and their consumption behavior remains a critical issue requiring in-depth investigation. Herein, based on survey data collected from 415 consumers in China in 2025, this study employs structural equation modeling (SEM) to analyze the determinants and mechanisms influencing green seafood consumption intention and behavior. The findings indicate that heightened concerns regarding dietary health, food safety, and nutrition significantly enhance consumer intention, driven primarily by ecological awareness and the pursuit of a higher quality of life. Individual and household characteristics, along with consumers’ cognitive status of green seafood, exert significant positive effects on consumption intention, with cognitive status demonstrating the strongest influence. Nevertheless, a notable gap exists between consumption intention and actual behavior. Among respondents with consumption intention, only 48.7% had ever purchased green seafood, and the consumption frequency remained generally low. SEM path coefficients further reveal that marketing factors play a dominant role in actualizing consumption behavior. Compared to marketing factors, consumption intention shows a relatively weaker effect in facilitating consumption behavior. This finding further confirms the intention–behavior gap in green seafood consumption. The intention–behavior gap in green seafood consumption is jointly driven by asymmetric information on product quality, an underdeveloped certification system, a relatively undiversified supply structure, and elevated prices. Accordingly, this study proposes an integrated strategy that includes establishing a unified certification and traceability system, optimizing supply structures and pricing mechanisms, and strengthening science communication and targeted marketing. These measures aim to bridge the intention–behavior gap and promote the transition toward sustainable consumption patterns. Full article

Water-In-Salt (WIS) electrolytes are expected to replace expensive, environmentally harmful organic electrolytes while delivering high voltages and improving system safety. In this study, analysis of the failure modes, mechanisms, and effects of a highly concentrated potassium acetate (KAc) electrolyte was conducted through electrolyte degradation at 2 V in a conventional EDLC carbon-based symmetric configuration. The adopted method provides a simplified yet effective approach for assessing the complexity and interconnectivity of degradation mechanisms in a WIS supercapacitor. The effects analysis included electrochemical stability studies, post-mortem characterizations (SEM-EDS and XPS), low-frequency impedance fitting, and cell reassembly using end-of-life electrodes. Among the failure modes analyzed, electrolyte decomposition and pore blocking exhibit strong physicochemical correlations and high failure rates. Therefore, they should be prioritized in the design of new WIS electrolyte compositions for next-generation energy storage systems. Full article

Semantic segmentation of remote sensing images (RSIs) is a fundamental task in geoscience research. However, designing efficient feature fusion modules remains challenging for existing dual-branch or multi-branch architectures. Furthermore, existing deep learning-based architectures predominantly concentrate on spatial feature modeling and context capturing while inherently neglecting the exploration and utilization of critical frequency-domain features, which is crucial for addressing issues of semantic confusion and blurred boundaries in complex remote sensing scenes. To address the challenges of feature fusion and the lack of frequency-domain information, we propose a novel dual-path feature extraction network (DFENet) in this paper. Specifically, a dual-path module (DPM) is developed in DFENet to extract global and local features, respectively. In the global path, after applying the channel splitting strategy, four feature extraction strategies are innovatively integrated to extract global features from different granularities. According to the strategy of supplementing frequency-domain information, a frequency-domain feature extraction block (FFEB) dominated by discrete Wavelet transform (DWT) is designed to effectively captures both high- and low-frequency components. Experimental results show that our method outperforms existing state-of-the-art methods in terms of segmentation performance, achieving a mean intersection over union (mIoU) of 83.09% on the ISPRS Vaihingen dataset and 86.05% on the ISPRS Potsdam dataset. Full article

In the state estimation problem for nonlinear systems, the Unscented Kalman Filter (UKF) has gained attention as an algorithm capable of accurate state estimation based on high-fidelity discretization for strongly nonlinear systems. Furthermore, for applying the UKF to continuous-time state–space models, a method employing the Runge–Kutta method in the time-update equation for sigma points has already been proposed to achieve high-precision state estimation. While this method uses high-order numerical approximations, the associated decrease in computational efficiency due to processing time becomes problematic. It is thus unsuitable for the state estimation of relatively fast-moving objects, such as autonomous vehicles and drones, which require high sampling frequencies. In this study, to reduce computational load while achieving relatively high estimation accuracy, we newly apply the Adams–Bashforth method to the UKF algorithm. The effectiveness of the proposed method is demonstrated by first explaining a low-dimensional model’s state estimation problem, followed by a comparison of estimation accuracy and computation time in state estimation simulations for the UAV model of an Osprey-type drone. Full article

Long-period ground motions (LPGMs), rich in low-frequency content, can resonate with long-period structures like high-rise buildings, leading to severe damage. As seismic design shifts from safety toward resilience, limited attention to LPGMs makes it difficult to ensure the seismic resilience of long-period structures. This study used Perform-3D software to model three high-rise reinforced concrete (RC) frame–shear wall structures with varying periods and one with infill walls for resilience assessment. The resilience indicators and seismic resilience grades under LPGMs and ordinary ground motions (OGMs) were compared using the Standard for Seismic Resilience Assessment of Buildings (GB/T38591-2020) and the Guideline for Evaluation of Seismic Resilience Assessment of Urban Engineering Systems (RISN-TG041-2022), which are national standards in China. The results show that the structural response under LPGMs is significantly different from that under OGMs. In particular, the influence of LPGMs on displacement-sensitive non-structural components is much greater than OGMs. Resilience indicators were higher under LPGMs. The presence of infill walls notably reduced resilience indicators, with a stronger effect under OGMs. Based on GB/T38591-2020, the seismic resilience of each structure generally decreases by 1–2 grades under LPGMs, while evaluations based on RISN-TG041-2022 show similar ratings under both LPGMs and OGMs. Full article

Permanent magnet synchronous motors (PMSMs) are utilized in demanding conditions and applications requiring precision and accuracy, such as servo systems. Especially at low speeds, the effects of cogging torque, current measurement and offset errors, improper controller gains, mechanical resonance, and torque fluctuations caused by load torque and flux result in fluctuations at various frequencies in the motor output speed. This study, motivated by two factors, proposes an extended state observer (ESO)-based multivariable fast response extremum-seeking (FESC) interval type-2 fuzzy PID (IT2FPID) controller to improve dynamic response and reduce speed ripple at low speeds in situations where all these negative factors could arise. This approach enables the real-time adaptation of parameters to counteract the decline in controller performance caused by the nonlinear characteristics of PMSMs and parameter fluctuations while also optimizing disturbance rejection in the speed response under varying operating conditions and existing speed ripple. The experimental results from the prototype setup validate that the proposed control mechanism is functional, valid, and precise in diminishing speed ripples during low-speed operations. The simulation and test outcomes of the control scheme show that speed noise at low speeds is reduced from 26% to 3% compared to traditional proportional-integral (PI) controller and supertwisting (STW) sliding mode controller (SMC) responses and that the scheme exhibits a 16–23% reduction in undershoot amplitude and faster recovery in the presence of load torque variations. Full article

Background: Gestational diabetes mellitus (GDM) affects many pregnancies worldwide and is associated with adverse maternal and fetal outcomes. Current screening at 24–28 weeks limits opportunities for early intervention. We evaluated whether machine learning (ML) models using first-trimester clinical and dietary data can predict GDM risk before the standard oral glucose tolerance test. Methods: We analyzed data from 797 pregnant women enrolled in the BORN2020 prospective cohort study (Thessaloniki, Greece). Ten ML algorithms were evaluated across five class-imbalance handling strategies using stratified 5-fold cross-validation, with final evaluation on an independent 20% held-out test set. Features included maternal demographics, obstetric history, lifestyle factors, and 22 dietary micronutrient intakes from the pre-pregnancy period assessed by Food Frequency Questionnaire. Results: The best-performing model (Logistic Regression without resampling) achieved an AUC-ROC of 0.664 (95% CI: 0.542–0.777), with sensitivity of 0.783 and NPV of 0.932 at the pre-specified threshold. The high NPV should be interpreted in the context of the low GDM prevalence (14.7%), as NPV is mathematically dependent on disease prevalence. A reduced nine-feature model using only routine clinical and demographic variables achieved a numerically higher AUC of 0.712 (95% CI: 0.589–0.825), with overlapping confidence intervals, indicating that detailed FFQ-derived micronutrient data did not improve prediction. Maternal age and pre-pregnancy BMI were the strongest individual predictors by SHAP analysis. No model reached the AUC >0.80 threshold for good discrimination. Substantial miscalibration was observed (slope: 0.56; intercept: −1.83), limiting use for absolute risk estimation. Conclusions: This exploratory study demonstrates that first-trimester ML models achieve modest discriminative ability for early GDM prediction, with routine clinical variables performing comparably to models incorporating detailed dietary assessment. These findings should be interpreted with caution, as no external validation cohort was available and the low events-per-variable ratio (~3.8) constrains the reliability of individual model estimates. Substantial miscalibration further limits use for absolute risk estimation. Accordingly, these models should be regarded as exploratory risk-ranking tools only and require external validation and recalibration before any clinical implementation. Full article