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In order to realize instant and accurate safety monitoring and early warning of key segments of coal mines, the development, structure and characteristics of "Internet of Things" (IOT) were discussed, which indicated that EPC Global and Ubiquitous ID (UID) systems are the most prevalent two models and Both contain “acquisition, transmission, processing and feedback of information”. After that, the physical model of safety expert system (SES) was established based on IOT, and the information acquisition segment was also introduced, which functioned as the core in the whole system. SES was thus utilized in coal mines which include different monitoring and control systems such as underground personnel monitoring system and automatic control system of main fan, and also an application example was discussed. The results show that the SES will be of great importance in safety monitoring and alerting of coal mines and worth promotion.

This paper introduces occurrence characteristics of coal bed methane in China, and analyses the influence of coal seam permeability on coal mine methane extraction. In addition, it presents the mechanism of increasing permeability by pressure relief. Lastly, the methane extraction technologies are discussed, and the applicable conditions of these technologies are analyzed. It is seen that choosing appropriate methane drainage technology, often in combination with several technologies including ground drilling, underground drilling, and pressure relief and permeability improving measures, is crucial for geological complex coal seam, especially low permeability soft coal seam.

The variation of coal body electrical parameters are important parameters for researches on the propagation of electromagnetic radiation and acoustic emission in coal. Therefore, experiments of coal body electrical parameters under triaxial stress are carried out. Studies have shown that, the resistivity of coal body decreases with the loading of axial compression and confining pressure. And the decline of raw coal is relatively more obvious, while the decline of briquette is smaller. Moreover, the resistivity of coal body retains relatively stable when the stress is greater than 3MPa. With the increase of axial compression and confining pressure, the dielectric constant of coal body will also increase and it will be basically stable when the stress is greater than 3MPa.

In order to research the dust removal process of dust agent in coal working face, we design the proportional adding equipment of mine-used dust-fall agent for static pressure pipes in coal working face and establish the calculation model of process parameters of this equipment combining with pipe flow theory of fluid mechanics, and theoretically analyze the selection rules of components such as the high pressure piston pump and pneumatic motor power.the proportional adding equipment has been applied to coal working face. From the results of the application, this equipment for reducing dust concentration in coal working face (especially PM2.5) has the obvious effect.

The gas-pulverized coal two phase flow law of gas is simulated by the use of the theory of jet after coal and gas outburst. Research results show that as the volume fraction of pulverized coal in outbursts mixture increases, the speed of two phase flow at the exit gradually reduces, jet core length shorter, turbulent longitudinal effect range smaller, jet width narrower. And dynamic head mainly concentrates in the jet core area and its distribution is more uniform in the roadways. The maximum speed of outburst two-phase flow decreases with the adding volume fraction of pulverized coal, that is higher the coal content in outburst mixtures, smaller the maximum speed after outburst. But a high content of coal have higher impact strike force which can cause major damage effect. The research may provide some theoretical basis for setting underground safety facilities, mine personal protection, disaster warning and emergency rescue.

According to the questions of long eliminating coal and gas outburst period, large projects and slow driving came from the regional measurement of drilling hole ,the paper select 2371 (1) rail transport roadway as experiment for using along seam long drilling as a regional measurement to eliminate coal and gas outburst. Since the regional measurement of along seam long drilling had been carried out, the remaining gas content decreased more than 60％, max Smax was 5.4kg/m, max qmax was 2.01/min.Both Smax and qmax were not beyond the standard. Gas concentrations were not overrun. Gas emission decreased in the roadway afterward. The regional measurement eliminated the risk of coal and gas outburst in effect. Heading face promoted 423m forward safely. The max January footage could reach 120m.Achieve driving of heading face safely and fast.

The experiment studied the variation of coal electric parameter using coal electric parameter testing system designed and processed by themselves. Raw coal sample and moulded coal sample were chosen as the study object. Studies have shown that the resistivity of coal sample decreases with increasing temperature. The resistivity of raw coal decreases significantly as the temperature increases, while the extent of decrease in moulded coal small. The dielectric constant of coal body decreases with increasing temperature. At the same temperature, the dielectric constant and the resistivity of moulded coal are both smaller than that of the raw coal. There are some theory and reference value of the experimental results for predicting coal and gas outburst with electromagnetic radiation.

To improve the low-permeability coal seam gas drainage and gas prevention and to seek the methods to improve the permeability of low-permeability coal, the experimental study on supercritical CO2 on coal was conducted in the laboratory conditions, and the experiment on pseudo-triaxial permeability testing for coal samples, with and without supercritical CO2, was conducted. The results show that due to the effect of supercritical CO2 on coal like physi-chemistry, the porosity of coal was changed, which markedly varied the permeability of coal samples before and after the effect of supercritical CO2; the permeability of the experimented coal samples was significantly higher than before, and average permeability increased by nearly an order of magnitude under the same volume-stress.

Insufficient investment in safety and irrational of security investment structure is one of the causes of accidents are occurring in the coal industry. This article takes fuzzy comprehensive evaluation on the rationality of the mine safety investment structure by M (1,2,3) model on the basis of the analysis of the correlation between coal mine safety input and safety production status. The evaluation results show that personnel training and investment in safety technology is the key of accident prevention, management investment is the main factor of affecting the rationality of coal mine safety investment structure; the fuzzy comprehensive evaluation based on M(1,2,3) model can improve the precision of fuzzy comprehensive evaluation.

Explosion suppression and isolation apparatus act as the last barrier to minimize casualties and property loss. Regrettably, the present techniques, such as water tubs and dust barriers, cannot effectively suppress multiple and continuous explosions. Being a porous medium, foam ceramics are characterized with large porosity and strong resistance against high temperature and shocks. Theoretical analysis and experimental study suggest that, due to numerous collisions with the walls in foam ceramics, the free radicals –generated in the chemical reactions of gas combustion and responsible for flame propagation, can be significantly destroyed, the reactive heat release be restrained, thus making the chemical reactions non-self-sustained. As a result, flame propagation is quenched. Furthermore, foam ceramics can markedly attenuate shock waves. Thus, if properly designed and arranged in the roadways, the material is expected to become a new-generation gas explosion suppression and isolation method in coal mines.

In order to improve the cutting efficiency of abrasive waterjet (AWJ), the relationship between pre-mixed AWJ cutting depth and pressure was experimentally studied. Then, through analysis of the cutting results, the topographic characteristics and formation mechanism of the cut trough faces were investigated. Moreover, through comparing the effects of different jet pressures on the topographic characteristics of AWJ cut trough faces and the SEM analysis of the cut trough faces at different pressures and depths, the effects of pre-mixed AWJ cutting mechanism on the characteristics of cut trough faces were investigated, and the characteristics of the trough faces of metals cut by pre-mixed AWJ were analyzed.

Electromagnetic emission (EME) is a kind of physical phenomenon accompanying the process of deformation and fracture of loaded coal and rock and it is of importance in quantitatively analyzing its characteristics. This will reveal the process of deformation and fracture of coal and predicting dynamic disasters in coal mines. In this study, the G-P (Grassberger and Procaccia) algorithm, calculation steps of the (if only 1 dimension) correlation dimension of time series and the identification standards of chaotic signals are introduced. Furthermore, the correlation dimensions of EME and the acoustic emission (AE) signals of time series during deformation and fracture of coal bodies are calculated and analyzed. The results show that the time series of pulses number of EME and the time series of AE count rate are chaotic and that the saturation embedding dimensions of a K3 coal sample are, respectively, 5 and 6. The results can be used to provide basic parameters for predicting of EME and AE time series.

The coal seam being mined by #3103 working face of Shangzhuang Coal Mine is relatively close to its adjacent seam. Moreover, the adjacent seam contains considerably high gas content. Therefore, in order to prevent excessive gas exceeding the stipulated limit as a result of massive gas emission from the adjacent seam during the initial collapse of the roof, forced caving scheme is worked out to deal with the roof of the working face based on the site conditions. On the one hand, pre-breaking blasting with deep holes adds up to the fissures in the upper adjacent seam, which not only enhances the effects of gas drainage in the adjacent seam in high position roadway, but prevents coal and gas outburst accident arising from floor collapse in large area. The practices proved that the forced caving scheme is feasible and effective to prevent outburst in the working face with upper adjacent seam.

Nowadays, following an accident in coalmines, what affects emergent rescue efficiency is mainly attributable to the uncertain positions and physiological state of coalmine ersonnel. In view of such problem, the wireless communication network and its node structure were designed for coalmines with the aid of the emerging ZigBee technique. With this system, the information on the coalmine personnel is collected by the portable terminal node placed in the miners' lamp cap. Then, the data is transmitted via the underground wireless network to the emergency rescue center on the surface, which helps to reaLize positioning of personnel and monitoring of emergency state and provide assistance for effectively conducting emergency rescue.

A mathematical model of the abrasive water-jet (AWJ) nozzle based on the multiphase hydrokinetics was established and the boundary conditions were determined. The liquid-solid flow rule of the cone nozzles with the cylinder section of the pre-mixed AWJ was simulated with the software FLUENT. The results show that the axial velocity and dynamic pressure of the continuous phase in the nozzle is notably of axial symmetry and the greatest value is at the axis; also abrasive are accelerated at two segments, which the rate increased rapidly in front contractive segment and the rate accelerated slowly in the back straight one. There is an extreme point of the rate between the 14 mm and 15 mm length for the model that the length of the cylinder is 100 mm, the diameter of the nozzle is 8 mm and the angle of the cone is 30deg. The simulation results provide the foundation for optimizing the nozzle structure, improving efficiency and developing the nozzle.