排序方式: 共有18条查询结果,搜索用时 15 毫秒
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低温使严寒地区混凝土面板堆石坝与常温地区设计方面会有所不同,本文针对两江水利枢纽工程混凝土面板堆石坝设计方面的一些要求,对严寒地区混凝土面板堆石坝设计的一些关键技术问题进行了探索,研究结果表明:通过提高面板混凝土抗渗抗冻标号,降低水灰比改善混凝土性能,适当增加面板钢筋含量,改善堆石坝结构设计,选择有利施工时段,改进表面... 相似文献
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为了进一步提高热流计的处理速度和精度,并给用户提供良好的操作界面,本文设计了一种基于WinCE和ARM处理器的嵌入式热流计系统.本系统以ARM9类型的微处理器S3C2410为核心,实现了高速数据采集误差校正.实验结果表明,本系统充分考虑的影响热流损失的相关因素,较传统的基于8位处理器的热流计在处理速度和用户操作界面上都有了较大的提高. 相似文献
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基因芯片网格定位是确定芯片上按栅格排列的所有荧光靶点二维坐标的图像分析过程。根据模板匹配的图像检测原理,采用归一化互相关测度对基因芯片图像与固定半径圆模板图像进行相似性计算,依次搜索二者之间的最佳匹配位置作为每个荧光靶点的中心位置。对6×6低密度基因芯片图像进行了网格定位分析试验,实现了芯片图像中全部靶点的检测和定位。试验表明,对于低密度芯片的网格定位,该方法具有原理简单和适应性强的特点,但算法效率有待提高. 相似文献
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朱荣 《武汉理工大学学报(材料科学英文版)》2011,26(6):1128-1132
Equal channel angular pressing (ECAP) processing and conventional extrusion (Ex) were applied to the Mg-12Gd-3Y-0.5Zr (wt%) magnesium alloy in order to evaluate the potential improvement in the mechanical properties. The ECAP experiment was conducted at 380 ℃ in a die having an included angle of 90° between two channels by the Bc route with the billet rotated by 90° about its longitudinal axis. Subsequently, some billets were processed by conventional extrusion at 300 ℃. The microstructures were examined by X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). The experimental results indicate that the grain size is refined effectively, but the basal planes are highly inclined (about 40o) from the extrusion axis introduced by ECAP, which impairs the grain boundary strengthening effect. The conventional extrusion, following the ECAP, can modify the grains in hard orientation. Based on grain boundary strengthening due to ECAP and texture strengthening due to Ex, the strength is improved effectively. The enhanced activity of the non-basal slips, due to the refined grains and the reduction in c/a ratio, is responsible for good ductility and high strain hardening rate in samples obtained by the two-step process. 相似文献
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采用不同浓度的Na2CO3溶液对高硅ZSM-5分子筛进行改性使其介孔化。对改性前后的ZSM-5分子筛进行了XRD、SEM、N2-吸附脱附和NH3-TPD等表征,并在小型固定床装置上考察了介孔化对正己烷催化裂解反应性能的影响。结果表明,调变Na2CO3溶液的浓度可以在保持骨架的同时产生介孔,增大分子筛的介孔孔容和总孔容,有效地调变分子筛的孔径分布;Na2CO3溶液改性ZSM-5分子筛对其正己烷的催化裂解活性几乎没有影响,但是由于介孔化处理优化了分子筛的扩散性能,在一定程度上减少了氢转移等二次反应,从而提高了丙烯的收率,丙烯的选择性明显增加。 相似文献
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