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A study on the bearing effect of pier column backfilling in the goaf of a thin coal seam
Jianlin Xie,Weibing Zhu,JiaLin Xu,Jiahui Wen,Chuanzhen Liu 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.3
The pier column backfilling method in the goaf of a thin coal seam introduced in this paper is the latest backfilling technology in China, which has the combined advantages of high efficiency and low cost. In order to fully verify the load bearing effect of this backfilling method, a comprehensive evaluation model which combined the actual measurement, numerical simulation and physical simulation is implemented in this paper. First, the stress bearing formula and backfilling volume rate of a pier column backfilling body is obtained by theory analysis. Then, through field monitoring, it was concluded that the bearing capacity when the backfilling body reached a stable state was similar to the results of theoretical calculation, and no obvious deformation occurred by observation the roadway deformation with the site. Finally, based on the drilling columnar and lithological parameters of the site, corresponding physical and numerical models were established and used to study the bearing effect of this backfilling method. It could be found that the stresses and displacements data that resulted from the simulation relatively confirmed data obtained from the site. After comprehension of above researches, it is concluded that the pier column backfilling method in a goaf has good bearing effect and a good economic benefit for mining thin coal seams.
Direct Torque Control for Induction Machine based on AC-AC Matrix Converter
Guo Yougui,Zhu Jianlin,Chen Caixue 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
The combination of matrix converter with direct torque control is a way towards green energy-saving of the world. It has great sense for theory research and good developing future. First, it is analyzed about working principle of matrix converter, the control principle and its realization process of direct torque control for induction machine inverterbased. Then the comprehensive switching control table is deduced according to the special properties of matrix converter together with direct torque control for induction machine. And the comprehensive modulation strategy can be concluded by looking up the table. Third, the simulation model is set up. The simulation results have verified the feasibilities and advantages of this novel alternative current adjustable speed system. Finally, an adaptive fuzzy PI controller was designed to improve the electric magnetic torque of induction machine.