The self-excited oscillation pulsed water jet is an efficient and valuable technology for cutting, especially for risky environments. In this paper, the pulsed water jet is explored to be used in high-risk environment for metal cutting. The abrasives are proposed to be added in to enhance its cutting ability. A portable cutting system is assembled and examined. The result shows that the cutting system is convenient and effective for risky environments.

In order to enhance Chinese workers' occupational safety awareness, it is essential to learn from developed countries' experiences. This article investigates thoroughly occupational safety and health (OSH) in China and the UK; moreover, the article performs a comparison of Chinese and British OSH training-related laws, regulations and education system. The following conclusions are drawn: China's work safety continues to improve, but there is still a large gap compared with the UK. In China a relatively complete vocational education and training (VET) system has been established. However, there exist some defects in OSH. In the UK, the employer will not only pay attention to employees' physiological health, but also to their mental health. The UK's VET is characterized by classification and grading management, which helps integrate OSH into the whole education system. China can learn from the UK in the development of policies, VET and OSH training.

In order to obtain the relationship between powder input, rotation rate, capacity of powder exhaust, power consumption, vibrational disturbance during normal operation of a spiral pipe, experiments of powder transport with different powder inputs (88-91, 133-137, 176-182g/s) and rotation rates (240, 300, 360, 420, 480, 540, 600rpm) are carried out. The results show that with the powder input remaining constant and the rotation rate increasing, the amount of powder residue obeys an exponential distribution and decreases gradually, and that the power consumption and vibration acceleration increase linearly. The results indicate that: (1) the capacity of powder exhaust is positively related to the rotation rate and (2) the higher the rotation rate is, the lower will be the marginal increment of powder exhaust. Through comparison of the images captured by a high-speed camera, the powder being transported falls within two flow regimes: (1) depositing and moving axially, and; (2) being stirred and moved spirally. Based on the comparison of the curves of powder residue, power consumption and vibration acceleration, a conclusion is drawn that the rotation rate of the spiral drill pipe in soft coal bed shall be controlled strictly and shall be neither too high nor too low.

Coal is the most important energy resource in China and accounts for 74% of China's primary energy consumption. Gas explosion is one of the most severe accidents in coal mine. In order to analyze the effect of foam ceramics suppressing gas explosion, laws of two kinds of foam ceramics - Al2O3 and SiC affecting gas explosion are studied in the gas explosion experiment system. The structure of the foam ceramics is tested and the mechanism of their suppressing gas explosion is analyzed. The experimental results show that foam ceramics has a significant attenuation of overpressure and propagation speed of gas explosion. The foam ceramics can absorb the energy of gas explosion but the effect is varied as Al2O3 ceramics performs better. The meso-structure of foam ceramics is obtained by digital microscope. The results suggest that foam ceramics is a kind of cellular material and the pore canals have a good connectivity, so the explosion flame can be quenched and the heat can be consumed by reflecting and refracting and the propagation speed of the transverse wave can be weakened. The process of foam ceramics adsorbing heat has been analyzed. The foam ceramics can terminate the process of the transmission of heat so the energy of gas explosion can be absorbed. The findings provide a new method for suppressing gas explosion in coal mines, especially multiple and continuous gas explosion.

Nowadays, the digitalization in coal mining industries has been developing. Especially with the development of the "concept of Industry 4.0", the coal mining industry is also facing a revolution. The key concept or technologies, such as Cyber Physical System (CPS), Machine to Machine (M2M) communication, and embedded calculation, and etc is being introduced to the coal mining industries. To realize the evolution from fully Mechanized coal face to fully automation and intelligent coal face, the coal mining industry is also running into its era of "Coal Mining Industry 4.0". In the so-called "Industry 4.0", machine perception is the core technology, and the localization and tracking is the key issue. The real time localization and tracking technology will provide the possibility for better collaborative work. In this paper, Ultra-Wideband (UWB) radio localization and tracking system especially for Long Wall coal face application is designed. The UWB radio propagation features are studied according to the geometric characters of the coal face, and spatial multipath channel model is proposed for coal face. This channel model is used to evaluation the Angle of Arrival (AoA) and Time of Arival (ToA) based localization algorithm. In this paper, the localization algorithm of high accurate ranging is developed for the homogenous network work, which is commonly installed for underground coal mining scenarios. With this algorithm, 10 cm localization accuracy is realized. This accuracy could satisfy, most of the application in coal face.