Abstract: A liquid nitrogen cyclic freeze-thaw permeability-improvement gas drainage method based on horizontal directional boreholes comprises: first constructing a main borehole at an intake roadway or a return roadway, a low-level roadway and a high-level roadway, after a drill bit reaches a pre-set target position of a coal bed, uniformly and directionally constructing a plurality of branch boreholes along a horizontal direction of the coal bed, injecting water to the coal bed, opening a valve, filling the main boreholes with liquid nitrogen, rapidly freezing the water injected into the branch boreholes and the periphery of the coal bed, and stopping injecting the nitrogen when an average temperature of a pre-permeability-improvement area monitored by a temperature measuring hole is lowered to ?2° C. or lower.

Abstract: A system and a method for automatically regulating the tensions of the guide ropes of a flexible cable suspension platform. The system includes a guide rope regulator mounted on a flexible cable suspension platform, a hydraulic pump station arranged on the flexible cable suspension platform, and a hydraulic system associated to the hydraulic pump station. The guide rope regulator automatically regulates the tensions of the guide ropes to enable the tensions of all the guide ropes to be consistent, so as to further ensure that the flexible cable suspension platform is in a level condition. The guide rope regulator also can measure the tension states of the guide ropes conveniently so as to ensure that the guide ropes have enough tensions to efficiently limit the swing amplitude of a lilting container. The system is simple, and convenient to operate, and has a good automatic regulating effect.