＂U＂ and ＂U＋I＂ type ventilation experiments were performed on a three-dimensional fully mechanized caving face simulation experimental platform. The distribution laws of the pressure field and gas field in the min...＂U＂ and ＂U＋I＂ type ventilation experiments were performed on a three-dimensional fully mechanized caving face simulation experimental platform. The distribution laws of the pressure field and gas field in the mine goal were obtained. Results show that the flow field in the goaf is generally asymmetric; the location of the gas accumulation area changes with ventilation parameters and can be used as an evaluation indicator to study the air leakage extent in the goal. Hence, drainage pipes buried in the goaf to intensively extract gas can be designed in such gas areas, which can give considerations in both improving gas drainage efficiency and reducing air leakage. By comparing the gas extraction effect of model experiments with that of on-site underground practices, the basic laws are commonly consistent according to comparative analysis. Thus the experimental results can be used to guide the application of underground gas prevent!o_n_and.control..展开更多
With the emergence of new Internet technologies, such as IPV6 （Internet Protocol Version 6） and Internet of things, the content of computer network course is increasing year by year and the contradiction between lim...With the emergence of new Internet technologies, such as IPV6 （Internet Protocol Version 6） and Internet of things, the content of computer network course is increasing year by year and the contradiction between limited teaching time and increasing teaching content appears. The widespread use of mobile Internet and the popularization of intelligent electronic devices make it difficult for students to focus their attention completely on the classroom. In view of the above two points, this paper redesigns the computer network classroom by using the Fanya SPOC （Small Private Online Course） teaching platform and adopting the teaching mode of flipped classroom to stimulate students＇ interest in learning and improve their learning effect.展开更多
Objective： To evaluate the effect of autograft bone, allograft bone, calcium sulfate bone cement, and calcium phosphate bone cement on the repair of tibial plateau defect in rabbits. Methods： We used autograft bone...Objective： To evaluate the effect of autograft bone, allograft bone, calcium sulfate bone cement, and calcium phosphate bone cement on the repair of tibial plateau defect in rabbits. Methods： We used autograft bone, allograft bone, calcium sulfate bone cement, and calcium phosphate bone ce ment to repair tibial plateau defect in rabbits. Gross and histo logic observations, Xray examination, and biomechanical test were conducted at 1, 2, 4, 8 weeks after operation. Results： Xray examination found that the bone den sity was evidently reduced in calcium sulfate group at 8 weeks after operation; there were no marked changes in other groups. The maximal load measurements showed that autograft and allograft groups were greater than calcium sulfate and calcium phosphate groups at 1 and 2 weeks after operation. However at 4 and 8 weeks after operation, no significant difference was found among the four groups. In autograft and allograft groups, there was no significant difference in biomechanical intensity at 2, 4, and 8 weeks,but it was significantly higher than that at 1 week. In cal cium sulfate and calcium phosphate groups, the outcome was ranked in descending order as 1 week〈 2 week〈 4 week =8 week. Histologic examination found a great amount of new bones at 8 week in both autograft and allograft groups. In calcium sulfate group, calcium sulfate was almost absorbed and there were numerous bone trabeculations. There was a large amount of unabsorbed calcium phosphate in calcium phosphate group. Conclusion： At 12 weeks postoperatively, the biome chanical intensity is higher in autograft and allograft groups than calcium sulfate and calcium phosphate groups, but after 48 weeks, there is no significant difference among groups. At 12 weeks, the biomechanical intensity in all groups is increased, but at 48 weeks, there is no significant increase. The rates of absorption and bone formation are quicker in calcium sulfate group than calcium phosphate group.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51174198 and 51304203)Supported by State Key Laboratory of Coal Resources and Safe Mining (No. SKLCRSM11X01)
文摘＂U＂ and ＂U＋I＂ type ventilation experiments were performed on a three-dimensional fully mechanized caving face simulation experimental platform. The distribution laws of the pressure field and gas field in the mine goal were obtained. Results show that the flow field in the goaf is generally asymmetric; the location of the gas accumulation area changes with ventilation parameters and can be used as an evaluation indicator to study the air leakage extent in the goal. Hence, drainage pipes buried in the goaf to intensively extract gas can be designed in such gas areas, which can give considerations in both improving gas drainage efficiency and reducing air leakage. By comparing the gas extraction effect of model experiments with that of on-site underground practices, the basic laws are commonly consistent according to comparative analysis. Thus the experimental results can be used to guide the application of underground gas prevent!o_n_and.control..
文摘With the emergence of new Internet technologies, such as IPV6 （Internet Protocol Version 6） and Internet of things, the content of computer network course is increasing year by year and the contradiction between limited teaching time and increasing teaching content appears. The widespread use of mobile Internet and the popularization of intelligent electronic devices make it difficult for students to focus their attention completely on the classroom. In view of the above two points, this paper redesigns the computer network classroom by using the Fanya SPOC （Small Private Online Course） teaching platform and adopting the teaching mode of flipped classroom to stimulate students＇ interest in learning and improve their learning effect.
文摘Objective： To evaluate the effect of autograft bone, allograft bone, calcium sulfate bone cement, and calcium phosphate bone cement on the repair of tibial plateau defect in rabbits. Methods： We used autograft bone, allograft bone, calcium sulfate bone cement, and calcium phosphate bone ce ment to repair tibial plateau defect in rabbits. Gross and histo logic observations, Xray examination, and biomechanical test were conducted at 1, 2, 4, 8 weeks after operation. Results： Xray examination found that the bone den sity was evidently reduced in calcium sulfate group at 8 weeks after operation; there were no marked changes in other groups. The maximal load measurements showed that autograft and allograft groups were greater than calcium sulfate and calcium phosphate groups at 1 and 2 weeks after operation. However at 4 and 8 weeks after operation, no significant difference was found among the four groups. In autograft and allograft groups, there was no significant difference in biomechanical intensity at 2, 4, and 8 weeks,but it was significantly higher than that at 1 week. In cal cium sulfate and calcium phosphate groups, the outcome was ranked in descending order as 1 week〈 2 week〈 4 week =8 week. Histologic examination found a great amount of new bones at 8 week in both autograft and allograft groups. In calcium sulfate group, calcium sulfate was almost absorbed and there were numerous bone trabeculations. There was a large amount of unabsorbed calcium phosphate in calcium phosphate group. Conclusion： At 12 weeks postoperatively, the biome chanical intensity is higher in autograft and allograft groups than calcium sulfate and calcium phosphate groups, but after 48 weeks, there is no significant difference among groups. At 12 weeks, the biomechanical intensity in all groups is increased, but at 48 weeks, there is no significant increase. The rates of absorption and bone formation are quicker in calcium sulfate group than calcium phosphate group.
