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《国际泥沙研究》2016,(4):376-385
Twenty runs of experiments are carried out to investigate non-equilibrium transport of graded and uniform bed load sediment in a degrading channel. Well-sorted gravel and sand are employed to compose four kinds of sediment beds with different gravel/sand contents, i.e., uniform 100%gravel bed, uniform 100% sand bed, and two graded sediment beds respectively with 53% gravel and 47% sand as well as 22%gravel and 78%sand. For different sediment beds, the experiments are conducted under the same discharges, thereby allowing for the role of sediment composition in dictating the bed load transport rate to be identified. A new observed dataset is generated concerning the flow, sediment transport and evolution of bed elevation and composition, which can be exploited to underpin devel-opments of mathematical river models. The data shows that in a degrading channel, the sand greatly promotes the transport of gravel, whilst the gravel considerably hinders the transport of sand. The promoting and hindering effects are evaluated by means of impact factors defined based on sediment transport rates. The impact factors are shown to vary with flow discharge by orders of magnitude, being most pronounced at the lowest discharge. It is characterized that variations in sand or gravel inputs as a result of human activities and climate change may lead to severe morphological changes in degrading channels. 相似文献
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构造应力是促进煤炭物理和化学变化的主要压力因素,造成地温局部升高,改变煤的结构。地温升高改变瓦斯动力机制,互相叠加后造成瓦斯含量、动力大幅度提高,给煤矿开采带来难度。 相似文献
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我国农村民居地震安全工作推进现状及国外经验 总被引：6，自引：1，他引：5
本文考虑农村民居地震安全工作推进方式的差异,对日美、拉丁美洲以及亚非部分国家的民居地震安全进行了简单综述,并对其特点和社会背景进行了简单分析。通过横向比较,得到了关于我国在推进农村民居地震安全工作时可以采取的一些方式;提出主要应该考虑的一些问题。 相似文献
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普及地震知识,搞好防震减灾工作 总被引：1，自引：0，他引：1
论述了地震知识宣传教育在防震减灾中的重要作用。阐明了通过防震抗震的宣传教育,使人们了解地震科学一般性常识,增强全民防灾意识,尽可能使地震损失减少到最低限度。 相似文献
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利用信息管理学的基本原理,按照中国现行的组织管理体制,总结分析现行的减灾工作的基本体制以及减灾信息资料建设、组织和传递方法。并通过对现今中国防灾减灾活动的分析归纳,探讨了市场经济条件下防灾减灾对策的信息管理模式。 相似文献
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