No abstract

China faces the problem of depletion of its coal resources, and a large number of mines are becoming aged mines. Demand for coal, however, still increases due to the growth of China’s economy. Energy shortage might restrict the sustainability of China’s national economy. As one contribution to a solution, this paper proposes the innovative exploitation method of solid backfill coal mining (SBCM) technology to exploit parts of pillar-blocked (residual coal pillar resources under industrial square, RCPRIS) that protect industrial facilities. Thus, blocked coal resources may be converted into mineable reserves that improve the recovery ratio of mine resources. Also, waste would be removed from the surface reducing hazards of environmental pollution. Based on the case of the Baishan Coal Mine in Anhui, China, numerical simulation is used to study the size of shaft-protecting coal pillars (SPCP) required at different backfill ratios. Results show that the disturbance to a shaft caused by exploitation decreases with the increase of the backfill ratio. When using SBCM to exploit RCPRIS under the condition of 80% backfill ratio, compared with the caving method, a lot of pillar-blocked coal resources would be freed. The life of Baishan Coal Mine would be prolonged, resulting in appreciable social, environmental, and economic benefits.

Silicosis is a fibrotic lung disease caused by inhalation of silica dusts, early and accurate diagnosis of which remains a challenge. We aimed to assess the performance of a nanofiber sensor array and pattern recognition to promptly and noninvasively detect silicosis. A total of 210 silicosis cases and 430 non-silicosis controls were enrolled in a cross-sectional study. Exhaled breath was analysed by a portable analytical system incorporating an array of 16x organic nanofiber sensors. Models were established by Deep Neural Network and eXtreme Gradient Boosting. Linear Discriminant Analysis was used for dimensionality reduction and visualized data analysis. Receiver Operating Characteristic Curve, accuracy, sensitivity and specificity were used to evaluate models. Results: 99.3% AUC, 96.0% accuracy, 94.1% sensitivity, and 96.3% specificity were achieved in test set. Silicosis cases present different breath patterns from healthy controls, classification results using which were highly consistent with the experts’ diagnosis. Breath analysis performed with the sensor array and pattern recognition is expected to provide a quick, stable recognition for silicosis. In this paper, different forms of features, different algorithms and data sets over long time periods were used, which provides a reference for silicosis expiratory diagnosis scheme.

A wear tester was developed. MC PA (nylon) filled with MoS2 and PU (polyurethane) were used as the material of the rubber wheel of roller guide shoes. Their wear performances was investigated with the tester. The results show that the wear rate of MC PA increases firstly and then decreases with increasing load, and reverses with increasing velocity. The wear rate of PU decreases firstly and then increases with increasing velocity. In addition, the main wear mechanisms of PU are plough wear and abrasive wear at the low load (200N). At the loads of 200N~500N, the main wear form of MC PA is the adhesive wear. Adhesive wear is the main mechanism of MC PA at the low velocity (3m/s). Due to inner heat accumulation by friction, squama-peering occurs on MC PA surface at the high velocity (8m/s). The dominant wear mechanisms of PU are abrasive wear and fatigue pitting. And the main reason of PU’s failure is the interior heat accumulation caused by friction.