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In order to study the advantages and disadvantages of dry mixed mortar and traditional shotcreting in underground shotcreting operation, and improve the mechanization level of underground shotcreting operation. This paper makes a statistical analysis on the use of dry mixed mortar shotcreting machines in 10 pairs of mines, such as Fucun and Tianchen of Zaokuang group. It is found that the dust content in the feeding point and the shotcreting point is higher, and the rebound is also higher. Six pairs of coal mines, such as Fucun and Tianchen, were selected to compare and analyze the shotcreting efficiency, rebound rate, dust rate and economic and technical indicators between dry mixed mortar and traditional mortar. The results showed that compared with traditional mortar, the shotcreting efficiency of dry mixed mortar was increased by 55.1%, the work efficiency was increased by 97.9%, and the rebound rate was reduced by 4.8%. Based on the above problems existing in dry mixed mortar shotcreting operation, the joint scientific research institute of Zao mining group put forward the schemes of bag feeding of finished dry mixed mortar and centralized feeding of finished dry mixed mortar, as well as the new shotcreting machine JSPB-8LX which can automatically adjust the water cement ratio, laying a foundation for the comprehensive promotion and application of dry mixed mortar under the mine.

Based on the analogy between equations of gas seepage in coal seam and that of thermal conduction, a simulative method on gas seepage in coal seam was proposed through that thermal conduction interpreted as gas seepage. The laws of gas emission from borehole in homogeneous and heterogeneous coal seam were analyzed using this method. It indicates that the simulative results of the gas emission from borehole in homogeneous coal seam were satisfied with the corresponding theoretical results during the early stage of gas seepage, while a tolerance between the numerical results and the theoretical ones was appeared in the later period. This is due to the simplification as solving the theoretical equations. The results of heterogeneous coal seam show that curves of gas emission rate conform to the actual situation. The numerical simulation method on the law of gas emission from borehole in coal seam is feasible.

For questions of the accident investigation of bridge，forensic engineering system of bridge is presented to find out the cause of collapse。New framework is proposed for forensic engineering system of bridge，including conception、principle、 independent investigation、member of investigation group、time limit of investigation and legal status of investigation conclusion.

Outburst cavity formed during coal and gas outburst can be pear shaped, elliptical, or just like an irregularly elongated ellipsoid, its capacity is always smaller than the volume of ejected coal. And the gas emission quantity is almost 4 to 10 times as gas content in ejected coal. These are two different expressions of the same problem. To find the reasons for the decrease of outburst cavity volume and the increase of gas emission quantity per ton, by using the finite element code ANSYS, the damage zone and the failure zone of the outburst cavity were determined based on the static and dynamic combination method. In this paper, the reason for the decrease of the outburst volume was explained.

Based on Fluid Dynamics and Combustion Theory, the model of pipeline was created by the software of CFD, and the spread of gas explosion was simulated in the conditions of pipelines of different lengths. The flame speed was obtained, as well as the the law of pressure changing with time in the pipeline. The results showed that the acceleration of flame speed could be divided into three phases: diffuse transmit, rise rapidly, inertial motion; oscillation pressure affected the turbulence of flame and was the significant reason to the rise of flame speed; when the pipeline got longer, the maximal flame speed would be higher, in addition, the transition distance that flame speed rise to a high value would tend to stable.

Based on the theory of nonlinear dynamic finite element, the control equation of coal and water jet was acquired in the coal breaking process under a water jet. The calculation model of coal breaking under a water jet was established; the fluid-structure coupling of water jet and coal was implemented by penalty function and convection calculation. The dynamic process of coal breaking under a water jet was simulated and analyzed by combining the united fracture criteria of the maximum tensile strain and the maximal shear strain in the two cases of damage to coal and damage failure to coal.

We report a case of cardiac tamponade due to air leak and fatal pneumopericardium that occurred after commercial flight transportation of a premature infant with chronic lung disease without respiratory distress. We review and discuss aspects of flight pathophysiology, and conclude that careful preparation before, and close monitoring during, commercial flight transportation is necessary for premature infants.