Surrounding rock control in the overlying protective coal seam is a challenging topic for de-stressed mining of multi-seamed coal.Current research findings on roadway control were used in the design of a physical mode...Surrounding rock control in the overlying protective coal seam is a challenging topic for de-stressed mining of multi-seamed coal.Current research findings on roadway control were used in the design of a physical model of a complex textured roof having a varying thickness.The model was used to study roadway instability and collapse caused by dynamic pressure.The results show that when the thickness of the roof exceeds the bolted depth the roadway security is least and the roof has the greatest possibility for collapse.Numerical simulations were also carried out to study stress redistribution before and after roadway excavation during underlying protective seam mining.The evolution of roadway displacement and fracture,as affected by support methods,has been well studied.A series of support principles and technologies for mining affected roadways has been proposed after demonstration of successful practical application in the Huainan Mines.These principles and technologies are of extended value to deep coal mining support in China.展开更多
The inverse relationship between the saturation magnetic flux density(Bs)and coercivity(Hc)of Febased amorphous alloys is a very active research topic that has been extensively debated.In this work,we conducted a deta...The inverse relationship between the saturation magnetic flux density(Bs)and coercivity(Hc)of Febased amorphous alloys is a very active research topic that has been extensively debated.In this work,we conducted a detailed investigation on the magnetic softness of Fe_(83.2-x)Co_(x)B_(10)C_(6)Cu_(0.8)(x=0 and 6 at.%)amorphous alloys based on analysis of the surface morphology,microstructure,magnetic anisotropy,and magnetic domain structure.Enhanced magnetic softness-magnetization synergy was realized in the present alloys by magnetic field annealing(MFA)during the de-stressing process.A dramatic 84%reduction of Hc to 2.2 A/m was achieved for the Co-doped alloy under MFA,exhibiting excellent magnetic performance with a superb Bs of 1.86 T.The consistency between the experimental results and theoretical analysis revealed that the MFA process can mitigate the trade-off between stress-induced anisotropy and induced uniaxial anisotropy owing to the homogenized structure formed by field annealing.Thus,the process favored a low Hc due to the significant continuous decline in the total magnetic anisotropy,which coincided well with the results of Magneto-optical Kerr microscopy.The study elucidates a mechanism for tuning Hc in Co-doped alloy systems and affords a possible pathway for softening amorphous alloys with high Bs.展开更多
The integrated extraction of coal and gas combines coal mining with gas capture. Taking into account the gas deposition and flow conditions in the Chinese coal basins, this paper describes the status of the theory and...The integrated extraction of coal and gas combines coal mining with gas capture. Taking into account the gas deposition and flow conditions in the Chinese coal basins, this paper describes the status of the theory and key technologies of this integrated extraction system, and presents its application and practice in the Shaqu, Zhongxing, Fenghuangshan and Pingmei mines. Areas for further improvements in future studies are discussed, focusing in particular on the fundamentals of the extraction system to make it greener, more scientific, and more advanced in both the exploitation and utilization of coal and the gas in coal.展开更多
基金Financial support for this work,provided by the National Key Technology R&D Program(No.2007BAK28B00)the National Natural Science Foundation for the Youth of China(No.50904064)+2 种基金the Research Fund for the Youth of China University of Mining & Technology(No.2008A004)the State Key Laboratory of Coal Resources and Safe Mining,CUMT(No.SKLCRSM09X03)the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety,CUMT(No.08KF10)
文摘Surrounding rock control in the overlying protective coal seam is a challenging topic for de-stressed mining of multi-seamed coal.Current research findings on roadway control were used in the design of a physical model of a complex textured roof having a varying thickness.The model was used to study roadway instability and collapse caused by dynamic pressure.The results show that when the thickness of the roof exceeds the bolted depth the roadway security is least and the roof has the greatest possibility for collapse.Numerical simulations were also carried out to study stress redistribution before and after roadway excavation during underlying protective seam mining.The evolution of roadway displacement and fracture,as affected by support methods,has been well studied.A series of support principles and technologies for mining affected roadways has been proposed after demonstration of successful practical application in the Huainan Mines.These principles and technologies are of extended value to deep coal mining support in China.
基金supported by the Anhui Provincial Natural Science Foundation(No.2208085QE121)the Key Research&Development plan of Anhui Province(No.2022a05020016)+2 种基金the University Natural Science Research Project of Anhui Province(No.2023AH051084)the National Natural Science Foundation of China(No.52071078)the“Zhishan”Scholars Programs of Southeast University(No.2242021R41158).
文摘The inverse relationship between the saturation magnetic flux density(Bs)and coercivity(Hc)of Febased amorphous alloys is a very active research topic that has been extensively debated.In this work,we conducted a detailed investigation on the magnetic softness of Fe_(83.2-x)Co_(x)B_(10)C_(6)Cu_(0.8)(x=0 and 6 at.%)amorphous alloys based on analysis of the surface morphology,microstructure,magnetic anisotropy,and magnetic domain structure.Enhanced magnetic softness-magnetization synergy was realized in the present alloys by magnetic field annealing(MFA)during the de-stressing process.A dramatic 84%reduction of Hc to 2.2 A/m was achieved for the Co-doped alloy under MFA,exhibiting excellent magnetic performance with a superb Bs of 1.86 T.The consistency between the experimental results and theoretical analysis revealed that the MFA process can mitigate the trade-off between stress-induced anisotropy and induced uniaxial anisotropy owing to the homogenized structure formed by field annealing.Thus,the process favored a low Hc due to the significant continuous decline in the total magnetic anisotropy,which coincided well with the results of Magneto-optical Kerr microscopy.The study elucidates a mechanism for tuning Hc in Co-doped alloy systems and affords a possible pathway for softening amorphous alloys with high Bs.
文摘The integrated extraction of coal and gas combines coal mining with gas capture. Taking into account the gas deposition and flow conditions in the Chinese coal basins, this paper describes the status of the theory and key technologies of this integrated extraction system, and presents its application and practice in the Shaqu, Zhongxing, Fenghuangshan and Pingmei mines. Areas for further improvements in future studies are discussed, focusing in particular on the fundamentals of the extraction system to make it greener, more scientific, and more advanced in both the exploitation and utilization of coal and the gas in coal.
