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Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To master the structure pattern and moving type of key strata is the basis of analyzing mine pressure in a fully mechanized mining face with large mining height. With the theoretical analysis applied，two structure patterns and six moving types of key strata were put forward，and the forming conditions of structure patterns and moving types were given. The two structure patterns include “cantilever” structure morphology in the caved zone and stable “hinged” structure morphology in the fractured caved zone. The six moving types include “cantilever” directly baggy fall type，“cantilever” bi-directional rotation baggy fall type，“cantilever” quadratic rotation baggy fall type，“cantilever-hinge” alternating movement type，“voussoir beam” moving type and “short voussoir beam” moving type. The six moving types of key strata in caved zone were verified by the UDEC numerical simulation method，and the different influence laws of the six moving types of key strata in caved zone on the mine pressure were revealed，which were also verified by the measured data. [ABSTRACT FROM AUTHOR]

In order to investigate the effects of relevant cutting parameters on specific energy,rock cutting tests were carried out using five conical picks with different cone angles on a sandstone under different levels of attack angles based on the linear rock cutting machine.The effects of relevant angles on cutting force and specific cutting energy were studied in detail.Some rock cutting tests were also carried out under different levels of depth of cut and line spacings with the attack angle of 55° using the conical pick with the cone angle of 55°.The effects of depth of cut and line spacing on cutting force and specific cutting energy were discussed in detail.Experimental results indicate that there is a significant influence of clearance angle on cutting force and specific cutting energy.If the clearance angle is too small,serious friction between the pick and rock would dramatically increase mean cutting force and further increase specific cutting energy.When the clearance angle is greater than 10°,mean cutting force linearly increases with the increasing cone angle of conical pick,and linearly decreases with the increasing rake angle.In this condition,the specific cutting energy is significantly smaller comparing with that under the clearance angle smaller than 10°.However,there is no obvious influence of rake angle and cone angle of the pick on specific cutting energy.The mean cutting force linearly increases with the increasing depth of cut and line spacing.The specific cutting energy increases with the increasing depth of cut with power function,and there is an optimum value of the ratio of line spacing to depth of cut to obtain the minimum value of specific cutting energy.The specific cutting energy under optimum relieved cutting approximately decreases by 65.1% comparing with that in unrelieved cutting mode.The optimum value of the ratio of line spacing to depth of cut is 2 or 3,and it is not affected by the depth of cut and line spacing.All conclusions of this study have an important guiding significance for designing the work angles of conical picks and picks arrangement on work units of mining machinery. [ABSTRACT FROM AUTHOR]