This paper analyzed the influence of mining depth, coal seam dip, mining height and face length on depth of floor water-conductive fissure zone.

This paper introduced the fast detection device of acting length of the sealing face which is suitable for on line detection of inlet and exhaust valve of the engine.

The effects of cutting area, contact arc length, the geometry of cutting face, back dip angle of PDC cutter and rock performance on force of PDC cutter breaking rock were simulated experimentally.