The spread of COVID-19 has changed the traditional education pattern, and prolonged home isolation and online learning have brought unprecedented challenges to second language teaching and learning. A sample of 1036 Chinese students from four representative middle schools participated in the research. The results indicated four motivations: intrinsic interest, learning situation, personal development, and immediate achievement. There were significant gender differences in English learning motivation. Moreover, intrinsic interest and personal development motivation had a significantly positive impact on English learning achievement, while learning situation had no significant impact, and immediate achievement motivation had a significantly negative impact. The findings highlight the cultivation of students’ learning autonomy and school-family interaction to promote the sustainable development of middle school students’ second language learning.

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Background Older adults are particularly at risk from infectious diseases, including serve complications, hospitalization, and death. Objective This study aimed to explore the drivers of vaccine hesitancy among older adults based on the “3Cs” (confidence, complacency, and convenience) framework, where socioeconomic status and vaccination history played the role of moderators. Methods A cross-sectional questionnaire survey was conducted in Jiangsu Province, China, between June 1 and July 20, 2021. Older adults (aged ≥60 years) were recruited using a stratified sampling method. Vaccine hesitancy was influenced by the 3Cs in the model. Socioeconomic status and vaccination history processed through the item parceling method were used to moderate associations between the 3Cs and hesitancy. Hierarchical regression analyses and structural equation modeling were used to test the validity of the new framework. We performed 5000 trials of bootstrapping to calculate the 95% CI of the pathway’s coefficients. Results A total of 1341 older adults participated. The mean age was 71.3 (SD 5.4) years, and 44.7% (599/1341) of participants were men. Confidence (b=0.967; 95% CI 0.759-1.201; P=.002), convenience (b=0.458; 95% CI 0.333-0.590; P=.002), and less complacency (b=0.301; 95% CI 0.187-0.408; P=.002) were positively associated with less vaccine hesitancy. Socioeconomic status weakened the positive effect of low complacency (b=–0.065; P=.03) on low vaccine hesitancy. COVID-19 vaccination history negatively moderated the positive association between confidence (b=–0.071; P=.02) and lower vaccine hesitancy. Conclusions Our study identified that confidence was the more influential dimension in reducing vaccine hesitancy among older adults. COVID-19 vaccination history, as well as confidence, had a positive association with less vaccine hesitancy and could weaken the role of confidence in vaccine hesitancy. Socioeconomic status had a substitution relationship with less complacency, which suggested a competitive positive association between them on less vaccine hesitancy.

In order to grasp the braking effect of the portal crane after the installation of auxiliary wind safety device, the braking process of real harbor crane with dual-stage windproof braking system exposed to fluctuating wind is simulated. The effect on the crane braking performance of braking device response lag and artificially lowering working braking force is also analyzed. It is demonstrated that the dual-stage brake system is superior to the single and could improve the windproof ability when working braking force decline.

The braking performance of open-air crane is essential to safety. Taking 40t Portal crane as the study object, this paper first analyzed and calculated the braking torque of traveling mechanism according to the design rules for cranes. Then the portal crane traveling mechanism model was established by the use of simulation software ADAMS, the braking process of crane of constant wind load was studied on typical operation conditions, and its braking performances were comparative analyzed. Finally, it can be concluded that it will substantially increase the crane braking time and braking distance after braking torque is adjusted small and cause hidden troubles of accident. The analytical method and conclusions of this paper can provide a theoretical basis to crane safety management.