It is very important to improve the cyclone separator separation efficiency for fine particles. On the basis of the Reynolds stress model (RSM), a new two-stage cyclone separation device is modeled and the model is simulated under six kinds of air volumetric flow rate conditions. The two-stage cyclone separator was then tested in the laboratory and the experimental data were compared with the simulation data. The results show that the RSM model can predict the performance of the two-stage cyclone separation device with high accuracy. Increasing of the air volumetric flow rate can not only improve the separation efficiency of the two-stage cyclone separator, but also effectively change the classification range. Because of the centrifugal force, even if the pressure drop is low, the 1st-cyclone can completely separate particles above 5.0 μm. When the air volumetric flow rate is more than 290 m 3 /h, the 2nd-cyclone can effectively separate the particles below 2.0 μm. The study also confirmed the nonlinear relationship between the pressure drop and the cut-off particle size and the maximum particle size. When the pressure drop exceeds a certain value, there is no longer any effect on the cut-off particle size and the maximum particle size.

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Teacher education is an important strategy for developing teachers’ technological pedagogical content knowledge (TPACK). Many schools in the world have incorporated the training into teacher education plans. However, there has been controversy in academic circles concerning the effects of teacher education intervention in promoting the development of teacher TPACK. Therefore, this study used a meta-analysis approach to review the published literature on teacher education programs to determine the impact on TPACK. The results showed that teacher education intervention positively affected TPACK (d = 0.839, p < 0.0001). Besides cultural background, experimental participants, types, sample types, intervention durations, differences in measurement methods, intervention types, and learning environments are the reasons for the differences in the effects of the interventions. The research design using random experiments had a significant positive effect on the size, which was significantly higher than that of the quasi-experiment. The longer the duration of teaching intervention, the stronger the improvement effect of teachers’ TPACK. There are significant differences in improving TPACK between teaching interventions, and the effect is more obvious. Teacher education intervention has a greater and slightly smaller impact on theoretical and practical knowledge. However, cultural background, experimental participant, sample type, and learning environment have no significant effect on teacher education intervention.

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Many factors influence student academic achievement, including tutoring and learning motivation. This research aimed to describe the influence of tutoring and learning motivation on Year 8 students’ mathematics achievement in one of the junior high schools in Ruteng, Indonesia in the academic year of 2019/2020. This descriptive research with survey design involved 66 students. Data were collected by administering a student questionnaire consisting of 20 questions. The 5-point Likert scale questionnaire used in this research focused on two categories: tutoring and learning motivation. The final semester test scores were used as the data on students' achievement in learning mathematics. The results revealed that the two factors were positively related to students' mathematics achievement; both contributed to student achievement by 18.49%. These findings confirm that tutoring and students’ motivation from teachers or parents are essential because both mediate student achievement. These results provide meaningful knowledge about the importance of teachers or parents providing structured tutoring to support the mathematics achievement of junior high school students.