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Strong mine tremor occurs frequently in deep mines, which have brought great hidden dangers to the safety of mine production. This paper takes panel 63/06 in No. 6 mining area of Dongtan coal mine as the research background, through geological survey, laboratory test, theoretical analysis, numerical simulation, on-site microseismic monitoring, the seismic evolution law and its mechanical mechanism, etc., and the conclusions are as follows: (1) there are three sets of key layer groups between the surface of the panel 63/06 and the coal seam, among which there is a large amount of energy in the thick Jurassic red layer and the lower key layer, which provides an energy basis for the red-bed to break and generate strong mine tremors; (2) on the plane, most of the strong tremors occurred in front of the mining position of the working face and tended to transfer to the side of the gob, and longitudinal, high-energy mine tremors are mainly distributed in high-level red sandstone; (3) the release location of high-energy mining earthquakes does not match the location of microseismic accumulation, indicating that there is no elastic energy accumulation in the lower surrounding rock before the strong mining earthquake occurs, and it highlights the characteristics of structural occlusal instability rather than energy abrupt instability in the rupture of the red and thick sandstone; and (4) the Dongtan red-bed type strong mine tremors have a large focal rupture radius, a long rupture duration, a small corner frequency, and a weak initial P wave, and the characteristics of low stress drop and no catastrophic nature indicate that the thick and low-strength red-bed is prone to large-scale fractures, which should belong to the structural instability type mine shock dominated by tensile fracture.

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The aim of the study is to further understand the rule of conversion of bottom hole pressure of a vertical well in a dual-permeability reservoir, which is about the dual permeability under different outer boundary (infinite, close, and constant value) conditions. However, there are few articles dealing with the model of a vertical well in a dual permeability reservoir under these three different outer boundary conditions. Hence, the paper proposes a model of a vertical well in a dual permeability reservoir under three outer boundary conditions. The model is solved with a Laplace space equation. We find the solution to the model that has a similar structure under three different outer boundary conditions by combining it with the similar structure theory. Therefore, we put forward a similar constructing method (SCM) that solves our model. The concrete steps of the SCM are given in this paper. At the same time, we draw the curves of the bottom hole pressure and pressure derivative using the modified Stehfest inversion formula and MATLAB software. In addition, we investigate the evolution of the pressure by changing the parameters (mobility ratio K, storability ratio ω , and crossflow coefficient λ ). The solution to such a reservoir model obtained in this paper could be used as a basis for analyzing other typical reservoirs with vertical wells.

Ion confinement technology can be widely used in quantum computation and precision measurement. In ion trapping system, ions are stably trapped in ion trap by the action of external forces.Multi-ion confinement requires the joint action of electric field and magnetic field to make the trapped ions overcome the interaction force between ions and be stably confined in the same specific space. Therefore, the stability of the electric force and the magnetic force determines the stability of ion confinement. Although the electric field and magnetic field provided by traditional commercial instruments is stable, it is not conducive to the miniaturization of the device. According to the previous experiment of ion confinement, we have designed a radio frequency(RF) signal generator that can provide continuous low power and stable high voltage RF electric field for multi-ion confinement system to guarantee the stability of trapped ions in quadrupole linear ion trap, also to improve the tapped ions density.