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煤与瓦斯突出是一种复杂的动力现象,突出的类型不同、引起突出的危险因素不同,预测指标对其的敏感性也就不同,选择适应的突出危险性预测敏感指标及突出敏感指标的临界值,研究可靠的突出预测手段和方法来实现对突出危险性的准确预测,是指导突出防治工作的重要技术基础,而为了获得突出敏感指标的临界值就必须对煤的多元物性参数进行实验研究,掌握煤层的各项物化性质,是有效确定防治突出方法体系的关键基础。 相似文献
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为实现钱家营矿掘进工作面煤与瓦斯突出实时预警,提出一种基于瓦斯涌出特征的预警方法。依据巷道高低浓度甲烷传感器实时监测数据,通过离散回归理论分析煤与瓦斯突出前的瓦斯涌出量,建立预警指标特征序列,确定掘进工作面煤与瓦斯突出预警指标危险临界值:方差0.018,波峰差0.41,波动斜率±0.027。在此基础上构建了非接触式煤与瓦斯突出可视化预警系统并在钱家营矿进行现场应用。结果表明,以瓦斯涌出特征值作为预警指标,能够准确监测到井下瓦斯异常现象,达到瓦斯数据实时解算和可视化预警的目的,为钱家营矿掘进工作面防突工作提供技术借鉴。 相似文献
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《Journal of Great Lakes research》2021,47(5):1305-1315
As sentinels of climate change and other anthropogenic forces, freshwater lakes are experiencing ecosystem disruptions at every level of the food web, beginning with the phytoplankton, a highly responsive group of organisms. Most studies regarding the effects of climate change on phytoplankton focus on a potential scenario in which temperatures continuously increase and droughts intersperse heavy precipitation events. Like much of the conterminous United States in 2019, the Muskegon River watershed (Michigan, USA) experienced record-breaking rainfall accompanied by unusually cool temperatures, affording an opportunity to explore how an alternate potential climate scenario may affect phytoplankton. We conducted biweekly sampling of environmental variables and phytoplankton in Muskegon Lake, a Great Lakes Area of Concern that connects to Lake Michigan. We compared environmental variables in 2019 to the previous eight years using long-term data from the Muskegon Lake Observatory buoy, and annual monitoring excursions provided historical phytoplankton data. Under cold and wet conditions, diatoms were the single dominant division throughout the entire growth season – an unprecedented scenario in Muskegon Lake. In 10 of the 13 biweekly sampling days in 2019, diatoms comprised over 75% of the phytoplankton community in the lake by count, indicating that the spring diatom bloom persisted through the fall. Additionally, phytoplankton seasonal succession and abundance patterns typically seen in this lake were absent. In a world experiencing reduced predictability, increased variability, and regional climate anomalies, studying periods of extreme weather events may offer insight into how natural systems will be affected and respond under future climate scenarios. 相似文献
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Miroslav Trnka Petr Hlavinka Mikhail A. Semenov 《Journal of the Royal Society Interface》2015,12(112)
Ways of increasing the production of wheat, the most widely grown cereal crop, will need to be found to meet the increasing demand caused by human population growth in the coming decades. This increase must occur despite the decrease in yield gains now being reported in some regions, increased price volatility and the expected increase in the frequency of adverse weather events that can reduce yields. However, if and how the frequency of adverse weather events will change over Europe, the most important wheat-growing area, has not yet been analysed. Here, we show that the accumulated probability of 11 adverse weather events with the potential to significantly reduce yield will increase markedly across all of Europe. We found that by the end of the century, the exposure of the key European wheat-growing areas, where most wheat production is currently concentrated, may increase more than twofold. However, if we consider the entire arable land area of Europe, a greater than threefold increase in risk was predicted. Therefore, shifting wheat production to new producing regions to reduce the risk might not be possible as the risk of adverse events beyond the key wheat-growing areas increases even more. Furthermore, we found a marked increase in wheat exposure to high temperatures, severe droughts and field inaccessibility compared with other types of adverse events. Our results also showed the limitations of some of the presently debated adaptation options and demonstrated the need for development of region-specific strategies. Other regions of the world could be affected by adverse weather events in the future in a way different from that considered here for Europe. This observation emphasizes the importance of conducting similar analyses for other major wheat regions. 相似文献
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针对依兰三矿极复杂地质条件下近距离突出煤层群开采时面临的瓦斯突出和回采工作面瓦斯超限、自然发火等问题,从保护层开采影响范围、开采后的残余瓦斯压力、回采面瓦斯涌出量、煤层自然发火角度分析了各煤层开采顺序,确定了首采面布置在上1煤层,从上至下依次开采较为合理。回采前确定采用千米定向钻机预抽中煤层巷道区域瓦斯+中煤层穿层钻孔预抽上1煤层条带瓦斯的区域消突方法;回采期间工作面采用高位钻孔+顺层钻孔的瓦斯治理方法,从而实现卸压抽采、条带消突预抽、实施防灭火工程等。采用以上瓦斯治理方法能够有效解决工作面瓦斯超限,达到了区域消突的目的,千米钻机长钻孔钻孔抽放浓度维持在80%以上,回风流瓦斯体积分数基本稳定在0.4%以下。 相似文献