Gas emission from the working face in a gas-bearing coal seam impairs safe production. Especially in the coal face, influenced by mining, pressure-relief gas in adjacent seams flows into the working face through the goaf. Moreover, caved overlying strata in different regions show differences in pore and seepage characteristics. Thus, the caving of overlying strata in the goaf of a working face was explored by carrying out physical similarity simulation. Then, based on the characteristics of the geometric shapes of caved overlying strata after mining, a trapezoidal three-dimensional model for gas extraction was established. According to the calculation result, the parameters of field high-level boreholes were optimized. Then, the controllability of gas concentration at the working face after gas extraction was assessed by applying statistical process control. The result showed that after the observed surface of the physical similarity model was lightened, it was more favorable for conducting the test. Moreover, the maximum gas concentration in the goaf was negatively correlated with the diameter of high-level boreholes and the negative pressure for gas extraction. A statistical process control chart revealed that the gas concentrations at the working face were safe after gas extraction based on high-level boreholes, which also validated the feasibility and effectiveness of the model.
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Experimental Study on Stress Transfer and Fracture Law During the Hydraulic Fracturing of Coal Seams
Geotechnical and Geological Engineering - Hydraulic fracturing is a key technology for increasing the permeability of coal seams and improving the extraction effect of coalbed methane. Exploring... 相似文献
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Hongguan Yu Weijia Guo Jiulong Cheng Qianting Hu 《International Journal of Coal Geology》2008,74(3-4):250-258
Modelling the sorption properties of coals for carbon dioxide under supercritical conditions is necessary for accurate prediction of the sequestering ability of coals in seams. We present recent data for sorption curves of three dry Argonne Premium coals, for carbon dioxide, methane and nitrogen at two different temperatures at pressures up to 15 MPa. The sorption capacity of coals tends to decrease with increasing temperature. An investigation into literature values for sorption of nitrogen and methane by charcoal also show sorption capacities that decrease dramatically with increasing temperature. This is inconsistent with expectations from Langmuir models of coal sorption, which predict a sorption capacity that is independent of temperature. We have successfully fitted the isotherms using a modified Dubinin–Radushkevich equation that uses gas density rather than pressure. A simple pore-filling model that assumes there is a maximum pore width that can be filled in supercritical conditions and that this maximum pore width decreases with increasing temperature, can explain this temperature dependence of sorption capacity. It can also explain why different supercritical gases give apparently different surface sorption capacities on the same material. The calculated heat of sorption for these gases on these coals is similar to those found for these gases on activated carbon. 相似文献
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Many global emission reduction strategies have been proposed, but few have been assessed quantitatively from the view of equality, efficiency and effectiveness. Integrated assessment models (IAM) is one of the effective ways to make climate policy modeling. So in this paper we developed the MRICES (Multi-regional integrated model of climate and economy with GDP spillovers) model, which is an IAM but extends to include GDP spillover mechanism, to make assessment on several strategies for global emission reduction, including the egalitarianism strategy, the UNDP strategy and the Copenhagen Accord. Using 1990 as a baseline for historical emission levels, the egalitarian strategy argues that developed countries should implement urgent emission reductions, whereas developing countries are allowed relatively higher future emission quotas. The UNDP strategy addresses the issue of substantial changes in global temperature but acknowledges that developing countries are not able to afford more costs for mitigation measures, which is inequitable from the perspective of a country’s right to develop. We also simulated the Copenhagen Accord to determine the consequences by the year 2100 if each country continues their current emission mitigation actions, and results indicated that the increase in global temperature will be 2.8 ℃by 2100; consequently, much stronger emission reduction efforts must be implemented after 2020. Based on analysis on mitigation strategies, it is recognized that the common but differentiated responsibility principle must be insisted when making global mitigation strategy. To comply with this principle, the emission reduction baseline of developed and developing countries should be discriminated, so 1990 and 2005 can be taken as the base year for developed and developing countries respectively. 相似文献
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粒度Hough变换及其在遥感影像直线检测中的应用 总被引：1，自引：0，他引：1
在基于Hough变换的遥感影像直线检测的过程中引入粒度计算的概念,利用粒度计算具有多角度、多层次观察问题的能力,对遥感影像中的直线边缘特征进行不同粗细的粒度分析,建立粒度计算概念下的直线检测算法,实现对不同长短、粗细直线的识别。真实的IKONOS遥感影像机场跑道提取试验证明了该方法的有效性。 相似文献
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水污染事故水质时空模拟和动态调控仿真系统研究 总被引：1，自引：0，他引：1
针对我国面临的重大水污染事故,结合一维系统动力学水质模型,将SD模型与GIS关联集成,开发基于二、三维一体化的水污染事故水质时空模拟和动态调控仿真系统;以2005-11发生的松花江水污染事件为例,进行水质模拟结果验证和可视化动态调控示范等,在时间和空间两个维度上对污染带迁移和转化进行动态模拟和趋势预测,实现了突发水污染事故水质浓度的模拟、预测和基于不同应急策略的模型调控。 相似文献
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传统村落是中华文明的鲜活载体,是中华历史、文化、自然遗产的“活化石”和“博物馆”,承载着中华传统文化的精髓。江西具有璀璨的历史文化,传统村落的时空格局的演化承载着江西历史的变迁和文化的传承。本文从历史地理学角度,结合历史文献和空间自相关分析、核密度分析、标准差椭圆、地理探测器等方法从历史、空间及文化3个维度对江西省343个传统村落的时空格局演化规律和影响因素进行研究。研究表明,从空间上看江西省传统村落在分布上具有明显的聚集性,且“热点”出现在上饶市婺源县与景德镇市浮梁县、抚州市东北部、吉安市中部3个区域,形成独有的“三核”分布模式。从历史线上看,江西省传统村落呈现出由“北（略偏东）—>南（略偏西）”的时空迁移特征;从村落分布选址角度,江西省传统村落大多分布在地势较为平坦、周围靠近水源的地区,江西省的盆地结构与密布的水网决定了自然因素是决定传统村落选址的首要因素,而文化的发展又促进了村落的扩张与壮大。在传统村落保护方面,经济的发展与城市的发展严重影响着传统村落的保护,政策的支持是目前传统村落保护的重要基石。 相似文献
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以武汉东湖为研究区域,利用MODIS数据和地面准同步叶绿素a浓度实测数据,建立适合东湖水体的叶绿素a浓度遥感定量估算模型,从而分析MODIS数据应用于内陆湖泊水体叶绿素a浓度反演的可行性。 相似文献
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Wei Pan Li Xuelong Hu Qianting Peng Shoujian Liu Shu 《Natural Resources Research》2020,29(6):4031-4051
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