In order to study the influence of the multiple interaction of coal and rock and the velocity effect of the cutting head on the flutter stability of the cutting head, considering the physical characteristics of coal and rock, the structural parameters of the cutting head and the motion parameters of the cutting head, the functional expression of the cutting depth of the cutting head and the participating cutting teeth is fitted, the cutting state mechanical characteristic equation of the dynamic cutting of the cutting teeth is established, and based on the mapping relationship between the cutting teeth and the cutting head, A cutting dynamic model including multiple interactions between cutting head and coal and rock and speed effect is constructed; An improved discrete method based on Newton Lagrange mixed interpolation is proposed, and the influence law of the coupling effect of regeneration effect and velocity effect on the stability of cutting flutter under cutting state is clarified; The improved full discrete method is compared with the full discrete method and the semi discrete method, and the superiority of the improved full discrete method based on the mixed interpolation method is proved; Based on the improved total discrete method, the influence of different cutting system dynamic parameters on the stability is studied. A cutting head coal rock system cutting test-bed is built to simulate the flutter of the cutting system. The results show that the improved fully discrete method can well predict the actual cutting state.
In order to study the influence of the multiple interaction of coal and rock and the velocity effect of the cutting head on the flutter stability of the cantilever roadheader, considering the physical characteristics of coal and rock, the structural parameters of the cutting head and the motion parameters of the cutting head, the functional expression of the cutting depth of the cutting head and the participating cutting teeth is fitted, the cutting state mechanical characteristic equation of the dynamic cutting of the cutting teeth is established, and based on the mapping relationship between the cutting teeth and the cutting head, a cutting dynamic model including multiple interactions between cutting head and coal and rock and the speed effect is constructed. An improved discrete method based on Newton–Lagrange mixed interpolation is proposed, and the influence law of the coupling effect of regeneration effect and velocity effect on the stability of cutting flutter under cutting state is clarified. The improved full discrete method is compared with the full discrete method and the semi-discrete method, and the superiority of the improved full discrete method based on the mixed interpolation method is proved. Based on the improved total discrete method, the influence of different cutting system dynamic parameters on the stability is studied. A cutting head coal rock system is built to simulate the flutter of the cutting system. The results show that the improved fully discrete method can reasonably predict the actual cutting state.
The self‐care practices of social workers have garnered increasing attention in the literature, yet little is known about the case of China. To explore the self‐care practices of Chinese social workers under the COVID‐19 pandemic, this study uses the Self‐Care Practice Scale (SCPS) to measure the self‐care practices of social workers (N = 1066) in Fujian Province, China. The results indicate that Chinese social workers engage in moderate amounts of self‐care practices under the COVID‐19 pandemic. Significant group differences exist in social workers' self‐care practices by marital status, parenting status, age, health satisfaction, years of practicing social work, average hours of work per day, resignation intention, job satisfaction, number of received supervision services in a year, and self‐care education. Significant predictors of self‐care include marital status, monthly salary, service status, average hours of work per day, number of received supervision services in a year, school self‐care education, job satisfaction, and health satisfaction. This study has practical implications for self‐care education and practice, including workplace health promotion and the development of self‐care practice policies.
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