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Due to hot toxic smoke and unknown risks under fire conditions, detection and relevant reconnaissance are significant in avoiding casualties. A fire reconnaissance robot was therefore developed to assist in the problem by offering important fire information to fire fighters. The robot consists of three main systems, a display operating system, video surveillance, and mapping and positioning navigation. Augmented reality (AR) goggle technology with a display operating system was also developed to free fire fighters&rsquo, hands, which enables them to focus on rescuing processes and not system operation. Considering smoke disturbance, a thermal imaging video surveillance system was included to extract information from the complicated fire conditions. Meanwhile, a simultaneous localization and mapping (SLAM) technology was adopted to build the map, together with the help of a mapping and positioning navigation system. This can provide a real-time map under the rapidly changing fire conditions to guide the fire fighters to the fire sources or the trapped occupants. Based on our experiments, it was found that all the tested system components work quite well under the fire conditions, while the video surveillance system produces clear images under dense smoke and a high-temperature environment, SLAM shows a high accuracy with an average error of less than 3.43%, the positioning accuracy error is 0.31 m, and the maximum error for the navigation system is 3.48%. The developed fire reconnaissance robot can provide a practically important platform to improve fire rescue efficiency to reduce the fire casualties of fire fighters.

The underground ventilation in coal mine comes from the ground air so that the seasonal fluctuation of atmospheric temperature inevitably has influence upon its climate. The paper obtains a simplified mathematical calculation method of the radial and axial temperature fields to furnish a supplement to air temperature prediction of coal roadway with the emphasis on the influence of seasonal characteristic of inlet airflow. The results reveal that the propagation of radial and axial temperature wave has the similar characteristic of amplitude decay and phase delay. In the radial direction, the main factor is the dimensionless annual cycle time; and in the axial direction, it is influenced by the location-related dimensionless time, the Nusselt number, the Biot number, and the dimensionless annual cycle time. In addition, for the wave amplitude, they present the negative exponential trend as the location increases, the overall shape of which resembles a folded page; for the delayed phase, they present the linear variation trend as the location increases, the overall shape of which resembles a parallelogram. In the paper, the evolution mechanism of temperature field of coal roadway under seasonal fluctuation boundary is profoundly comprehended, which has important guiding significance for the field engineer.

In order to study the propagation law of shock waves and gas flow during coal and gas outburst, we analyzed the formation process of outburst shock waves and gas flow and established the numerical simulation models of the roadways with 45° intersection and 135° intersection to simulate the propagation of outburst gas flow and the process of gas transport. Based on the analysis of the simulation results, we obtained the qualitative and quantitative conclusions on the characteristics and patterns of propagation and attenuation of outburst shock waves and gas flow. With the experimental models, we investigated the outburst shock waves and gas flow in the roadways with the similar structures to the simulated ones. According to the simulation results, when the angle between the driving roadway and the adjacent roadway increased, the sudden pressure variation range in adjacent roadway and the influencing scope of gas flow increased and the sudden pressure variation duration decreased. The intersection between the driving roadway and the adjacent roadway has no effect on airflow reversal induced by the shock waves and gas flow. Keywords: Coal and gas outburst, Shock waves and gas flow, Propagation law, Cross roadway