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通过电渣重熔制备不同硅含量的M2高速钢铸锭(硅质量分数分别为0.3%,0.8%,1.6%和2.4%),采用光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)的方法研究了硅对热处理态M2高速钢中共晶碳化物的影响。研究结果表明,退火态高速钢铸锭中共晶碳化物呈连续或半连续网状分布于枝晶间,随着硅含量的增加,共晶碳化物从片层状M2C变为鱼骨状M6C。在1 165 ℃保温2.5 h的热处理过程中,片层状M2C碳化物分解为MC和M6C碳化物,在后续变形中破碎为细小的碳化物颗粒。0.8%S 相似文献
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以区分非最优约束条件和最优约束条件的特性为主线,利用线性规划、线性代数等理论进行分析和推导,从理论上获得了非最优约束条件一些性质及识别非最优约束条件的定理。在求解大规模解线性规划问题时,可以利用所得到的结论构造新的求解方法,以在求解的过程中获得变量有关的信息来识别非最优约束条件,并及时删除它,使得模型逐步降阶,以提高求解效率。 相似文献
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Fire statistics and fire analysis have become important ways for us to understand the law of fire, prevent the occurrence of fire, and improve the ability to control fire. According to existing fire statistics, the weighted fire risk calculating method characterized by the number of fire occurrence, direct economic losses, and fire casualties was put forward. On the basis of this method, meanwhile having improved K-mean clustering arithmetic, this paper established fire risk K-mean clustering model, which could better resolve the automatic classifying problems towards fire risk. Fire risk cluster should be classified by the absolute distance of the target instead of the relative distance in the traditional cluster arithmetic. Finally, for applying the established model, this paper carried out fire risk clustering on fire statistics from January 2000 to December 2004 of Shenyang in China. This research would provide technical support for urban fire management. 相似文献
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吴立志 《科技情报开发与经济》2007,17(30):83-84
从高校图书馆的管理模式、文献资源建设、读者服务工作、数字图书馆技术研发等方面探讨了网络环境下如何改进高校图书馆工作模式,促进高校图书馆健康发展的问题。 相似文献
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