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Coal fires are emerging as a global threat with significant economic, social and ecological impacts, besides the loss of energy resources those fires cause air and water pollution and emit enormous amounts of green house gases (carbon dioxide and methane), how to prevent and extinct the fires has been a worldwide issue. According to the respective limitation and characteristic of gel fire prevention materials and foam fire prevention materials, a new thinking of foamed gel coal fire prevention materials is put forward creatively. Foamed gel that includes the characteristic of gel and foam possessed the property of accumulation. It also has the performance of sealing and secluding oxygen. This paper describes the composition and characteristic of foamed gel, as well as the laboratory production process. For large coal fire zones, the new fire prevention materials (Foamed Gel) have a broad application prospect.

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Layout of stations and height of aircraft are very important to localization accuracy of wide area multilateration (WAM) system, and the error produced by layout of stations and height of aircraft may influence WAM system's localization accuracy. To find the approach to reduce the error, this paper firstly calculates relationship between localization accuracy and height error according to hyperbolic algorithm and least square method, and obtains the change law of horizontal dilution of precision (HDOP) and vertical dilution of precision (VDOP) with height. Secondly, the system localization precision of levels of the same height and levels of different aircraft heights after giving consideration to the various circumstances of wide area stations layout are simulated and analyzed. Thirdly, the impact of different station layouts and baseline length of the levels of the same height on localization precision are discussed. Simulation and discussion results show that the aircraft height has a large impact on the WAM system's localization precision. In particular, the vertical localization precision reduces obviously when the height is low. When the height is unchanged, a proper station layout and baseline length can improve the system's localization precision.

The lack of systematic geological work is an essential reason why underground coal gasification (UCG) has not been industrialized for a long time. Building a scientific index system and favorable area evaluation technology for the UCG site selection is the key to breaking through the geological bottleneck. Aiming at the problems of the single index weight determination method, intense subjectivity, and poor reliability of current evaluation models, we put forward an evaluation modeling methodology for the UCG site selection using the combination weighting method with the game theory. The factors of coal resource conditions associated with the potential risk of UCG are systematically analyzed. From the six dimensions of the geological structure, hydrogeology, seam occurrence, coal properties, reserves, and roof lithology, 23 key factors were selected as evaluation indexes to construct a hierarchical model composed of the target layer, category index layer, and index layer. The influence of each index on UCG and its reasonable value range were systematically analyzed. The evaluation index system for UCG site selection was formed. The improved analytic hierarchy process (AHP) was adopted to sequence indices and determine their subjective weight. And the variability, conflict, and information amount of the index data were analyzed by the CRiteria Importance Through Intercriteria Correlation (CRITIC) method to calculate the objective weight. Then, the subjective and objective weights were combined through game theory. On this basis, fuzzy theory was employed to calculate the membership of indices and construct the fuzzy comprehensive judgment matrix. The evaluation model of the UCG site selection was applied to the suitability evaluation of resource conditions of UCG pilot projects at Zhongliangshan (ZLS), Huating (HT), and Shanjiaoshu (SJS) mines in China. The result shows that the resource conditions of HT are the best, followed by ZLS and, finally, SJS, which are consistent with the actual running effects of the three UCG pilot projects. It indicates that the evaluation model can provide a scientific theoretical basis and reliable technical support for the UCG site selection.