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Hydrogen refueling stations are increasingly being built in densely populated urban areas and operating under high temperature and pressure conditions. Therefore, the safety of hydrogen refueling stations has received great attention. In present work, a new dynamic quantitative risk assessment method is established for hydrogen leakage at refueling stations based on Bayesian networks (BN). Firstly, risk factors are identified using a fault tree, considering multiple equipment operating states. A Dynamic Bayesian Network (DBN) is established, and event tree analysis is combined to determine accident consequence probabilities. Furthermore, a Bayesian Domino Model is constructed to assess the impact of accident consequence propagation on the probability and risk of hydrogen leakage accidents. Through a typical case study of an off-site hydrogen refueling station, the practicality of the proposed method is validated, the risk factors and safety barriers, the dynamic evolution of hydrogen leakage probabilities within a three-year period are obtained. The probability of hydrogen leakage in hydrogen station is 2.69 × 10−2 in the first month and 2.45 × 10−2 in the 36th month. Simultaneously, the maximum personal risk value for the first month is 5.07 × 10−4. When the Domino effect is considered, the maximum accident probability is 1.96 × 10−3 is obtained in the first month, and the equipment unit with the greatest impact of the accident is A2. Measures were also proposed to reduce hydrogen leakage risks during the operation of off-site hydrogen refueling stations, with an emphasis on prioritizing safety measures for hydrogen storage bundles and risk mitigation strategies. [Display omitted] • Risk assessment for supply at tube trailers hydrogen refueling stations was finished. • DBN for hydrogen leakage and BN for the accident domino effect were established. • The dynamic probability, key risk factors and safety barriers were obtained. • The probability of the accident domino effect at various levels were proposed. • Individual risk values and ranges of accident damage zones were confirmed. [ABSTRACT FROM AUTHOR]

An ultra-narrow precision slit with a width of less than ten micrometers is the key structure of some optical components, but the fabrication of these structures is still very difficult to accomplish. To fabricate these slits, this paper proposed a periodically reducing current over-growth electroforming process. In the periodically reducing current over-growth electroforming, the electric current applied to the electrodeposition process is periodically stepped down rather than being constant. Simulations and experimentation studies were carried out to verify the feasibility of the proposed process, and further optimization of process parameters was implemented experimentally to achieve the desired ultra-narrow precision slits. The current values were: I 1 = I i n i t i a l ,   I 2 = 0. 75 I i n i t i a l   a t   Q c = 0. 5 Q t ,   I 3 = 0. 5 I i n i t i a l   a t   Q c = 0. 75 Q t , r e s p e c t i v e l y.   It was shown that, compared with conventional constant current over-growth electroforming, the proposed process can significantly improve the surface quality and geometrical accuracy of the fabricated slits and can markedly enhance the achievement of the formed ultra-narrow slits. With the proposed process, slits with a width of down to 5 ± 0.1 μm and a surface roughness of less than 62.8 nm can be easily achieved. This can improve the determination sensitivity and linear range of the calibration curves of spectral imagers and food and chemical analysis instruments. Periodically reducing current over-growth electroforming is effective and advantageous in fabricating ultra-narrow precision slits. [ABSTRACT FROM AUTHOR]

In this work, epoxy (EP) resin composites with multi-scale reinforcements were prepared by hand lay-up and hot-pressing. The epoxy was reinforced with basalt fibers (BF) modified with a silane coupling agent (KH560). Carboxylated multi-walled carbon nanotubes (CNTs) were also grafted onto the surface of the modified BF using an impregnation method to achieve BF/CNTs multi-scale reinforcement. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) showed that KH560 was successfully grafted onto the BF surface. Scanning electron microscopy (SEM), indicated a better resin adhesion on the BF and thus a stronger interfacial interaction in the BF/CNTs-reinforced composite. It was observed that the mass fraction of KH560 was a significant parameter in achieving desirable CNT immobilization and mechanical properties of the composites. At an optimal mass fraction of KH560 (5%), the tensile, flexural, and interlaminar shear strength (ILSS) of the modified composite (BF-5%KH560-CNT/EP) increased by 12.5%, 20.9%, and 25.5% respectively compared with the BF-washed/EP composite due to more efficient load transfer. In addition, compared with BF-washed/EP, the decomposition onset temperature of BF-5%KH560-CNT/EP increased from 387°C to 396°C, the maximum decomposition rate temperature increased from 400°C to 408°C, and the residual weight increased by 5.8%. [ABSTRACT FROM AUTHOR]

Aim: This study aimed to characterize the pathological types, diagnosis, chromosomal abnormalities, and postnatal clinical manifestations of right and double aortic arch malformations in fetuses. Methods: In this retrospective study, all fetuses diagnosed with right or double aortic arch anomalies for whom conventional two‐dimensional echocardiography combined with spatio‐temporal image correlation was performed at our tertiary referral center between December 2012 and December 2021 were included. Results: In total, 234 fetuses with aortic arch abnormalities were identified. Forty‐one cases lost to follow‐up. One hundred ninety‐three cases were included in this study. One hundred eighty‐seven cases with right aortic arch. Six cases with double aortic arch. Most cases of right aortic arch with aberrant left subclavian artery (77/101, 76.2%) were isolated lesions, whereas most of those with mirror‐image branching (45/75, 60%) were associated with intracardiac or extracardiac anomalies. Chromosomal abnormalities were screened prenatally in 113 fetuses with right aortic arch, among whom three with aberrant left subclavian artery (3/63, 4.8%) and eight with mirror‐image branching (8/50, 16%) had chromosome anomalies (p < 0.05). Furthermore, three cases had microdeletion 22q11.2 and these were significantly associated with intracardiac malformations. Conclusions: Most cases of isolated right aortic arch do not present with clinical symptoms except isolated left subclavian artery and isolated left brachiocephalic trunk. In addition, the risk of chromosomal abnormalities in patients with isolated right aortic arch is very low. We recommend that pregnant women should be informed of the risks and benefits of undergoing invasive prenatal chromosomal detection. [ABSTRACT FROM AUTHOR]