No abstract

Emergency management of coal mines requires enhanced synergy among departments, institutions, and enterprises, which means overall efficiency in management. Their synergy can effectively lower the cost of emergency management, improve the effectiveness of it, and build a strong joint force for the prevention and control of emergencies. Accordingly, this study established a synergy system for regional coal mine emergency management and analyzed the interest relationship among key stakeholders in the system. Then, it established differential game models of the management synergy, explored the selection process of the behavior strategy of each stakeholder under different situations, and provided important tools for quantitative analysis on emergency management synergy practice. Furthermore, numerical simulation was carried out to analyze the influencing factors of their decision behaviors. The research results are of great significance for the comprehension of the evolution mechanism for the emergency management synergy of coal mines, the assistance for the government in determining the optimal method in emergency management synergy, the mobilization of the stakeholders, and the improvement of the current situation of emergency management synergy of coal mines in China.

An RMT-150B electrohydraulic servo testing system was used to perform uniaxial compression and uniaxial grading relaxation (creep) tests. The deformation, strength, and failure characteristics of the progressive failure process of coal samples under three loading modes were analyzed. The analysis results show that the prepeak stress-strain curve of the coal samples and the load relationships are not clear and that the whole compression process of coal still showed compression, elastic, yielding, and failure stages. The local stress drop characteristics during our relaxation creep grading tests showed no clear peak value and showed a yield curve with the shape of a conventional single plateau. The values of the mechanical parameters of axial compression were significantly higher than those obtained in the grade relaxation (creep) tests, which showed the mechanical parameters of coal samples with aging characteristics. In the relaxation (creep) tests, when the stress ratio was less than 70%, the relaxation (creep) characteristics of the sample were not clear. When the ratio of stress relaxation (creep) was more than 70% in the relaxation (creep) tests during displacement (stress) with a constant relaxation (creep) over the duration of the test, the evolution, development, and convergence of microcracks in the coal samples were observed. Relaxation (creep) stress was higher, failure duration was shorter, and the duration of failure was longer. For fully mechanized coal faces, increasing the support resistance and timely moving the support after coal cutting may prevent rib spalling accidents by reducing coal stress and exposure time in the front of the working face. Additionally, routine uniaxial compressive failures showed a simple form, having a clear tension-shear dual rupture surface. The staged relaxation creep failure testing of coal is more complex. The entire coal samples were divided into many thin-sheet debris via gradual collapse and shedding, and the number of cracks increased significantly, showing evident lateral expansion characteristics that are similar to the rib spalling characteristics in high coal mining working faces.

Emergency management of coal mines requires enhanced synergy among departments, institutions, and enterprises, which means overall efficiency in management. In this study, a regional coal mine emergency (CME) management synergy system was established; the synergy theory was adopted to construct the order parameter index system of the regional CME management synergy subsystems. Moreover, the order degrees and synergistic degrees of the regional CME management synergy subsystems in Henan Province, China, in the period 2015-2019 were quantitatively measured and analyzed using the composite system synergy model. The results show that the order degrees of regional CME management synergy subsystems and the synergistic degree of the composite system increase overall during the inspection period. With the gradual formation of the regional CME management synergy mechanism, this period has witnessed a steady improvement in both the synergy value and the considerable synergistic effect.

The design and construction of Ag2S heterostructures capable of significantly separating photocarriers is a significant challenge in photocatalysis. In this study, CdS/Ag2S heterojunction composite photocatalyst is fabricated through a simple one‐step hydrothermal method. The composite structure is characterized by X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and UV‐visible diffuse reflection spectroscopy. Under visible light irradiation, the photocatalytic activity of the sample is evaluated by degradation of methyl orange. The photoelectric chemical performance of the CdS nanoparticles modified by Ag2S is closely related to the ratio of Cd/Ag cation. The experimental results show that the sample ACS‐2 (CdS‐Ag2S = 1:1) composite has higher charge transfer/separation efficiency and longer carrier life. The degradation efficiency reaches 74.4% within 30 min, and the degradation rate constant is 0.047 min−1. After four cycles, the degradation efficiency of the catalyst only decreases slightly, indicating that the CdS/Ag2S catalyst has good stability and repeatability. Meanwhile, the study of the photocatalytic mechanism shows that •O1− is the primary active substance in the catalytic process, and h+ and •OH play a secondary role. This work provides a great significance for constructing efficient Ag2S‐based heterojunction photocatalyst systems.