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沛县,是汉高祖刘邦故里,素有“千古龙飞地,一代帝王乡”之美誉。沛县也是江苏省煤炭主产地和华东地区主要煤炭生产基地之一,年产煤炭量占全省的69%。然而,煤炭在为沛县带来丰硕经济效益的同时,也带来了生态治理的难题。煤从地下一点点地被开采了出来,地却一点一点地向下陷,坑洼不平、积水成湖,原本生活的乐园,成了沛县人深恶痛绝的“塌陷湖”。 相似文献
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由辐射传输方程推导星载被动微波遥感SSM/I辐射观测的极化指数PI,凸现地表土壤湿度的变化与距平异常ΔnPI,用特征性指数PI、ΔnPI和散射指数SI来监测大尺度陆地地面的降雨和地区土壤湿度、洪涝汛情的变化.用中国淮河流域7年同月SSM/I观测数据的平均<PI>,洪涝期间的PI,ΔnPI和SI监测该流域2003年7月的洪涝汛情.提出距平异常值指数K分布,定量评估了洪涝汛情的范围和程度. 相似文献
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Ten full-scale steel beam-to-column moment connections used in moment-resisting frames (MRFs) were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one traditional welded flange-bolted web connection, one traditional fully welded connection, four beam flange strengthened connections, three beam flange weakened connections, and one through-diaphragm connection. The test results show that the connections with flange cover plates or with partly cut beam flanges satisfy the beam plastic rotation demand for ductile MRFs. From the measured stress profiles along the beam flange and beam web depth, the mechanics of brittle fracture at the end of the beam is discussed. Design recommendations for steel beam-to-column moment connections are proposed. 相似文献
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