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The optical properties of Er3+-doped and Yb3+/Er3+ co-doped 12CaO·7Al2O3 (C12A7) poly-crystals, synthesized by high temperature solid state method, were investigated in detail. For Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals, two main emission bands centered around 530/550 nm (green) and 660 nm (red) were observed under 980 nm diode laser excitation via an up-conversion process. The intensity of green up-conversion emission had a strong increase in Er3+ (1.0 mol.%, 1.5 mol.%, 3.0 mol.%), and the i... 相似文献
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采用落锤冲击加载反射式焦散线实验系统,对经过镜面移植工艺加工的几种典型的天然变质岩(汉白玉、大理岩和板岩)和类岩石(人造石和水泥石)试件进行冲击断裂实验,得到类岩石材料的裂纹尖端焦散斑,但没有得到天然岩石材料的焦散斑。进而对未经镜面移植工艺加工的试件进行落锤冲击断裂的高速摄影实验,发现天然变质岩试件冲击断裂过程中,试件表面首先出现"白带纹",与类岩石试件存在明显差异。通过对2种实验中裂纹出现时间和传播速度的对比分析,发现采用反射式焦散线实验无法记录下经镜面移植工艺处理的天然变质岩试件中微裂纹的发育和部分扩展过程,移植的镜面掩盖了天然岩石试件断裂过程中微裂纹的发育和扩展现象,导致天然变质岩石的焦散线实验难以成功。 相似文献
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The optical properties of Er3+-doped and Yb3+/Er3+ co-doped 12CaO·7Al2O3 (C12A7) poly-crystals, synthesized by high temperature solid state method, were investigated in detail. For Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals, two main emission bands centered around 530/550 nm (green) and 660 nm (red) were observed under 980 nm diode laser excitation via an up-conversion process. The intensity of green up-conversion emission had a strong increase in Er3+ (1.0 mol.%, 1.5 mol.%, 3.0 mol.%), and the intensity ratio of red to green up-conversion emission had an increase in Yb3+ (1.0 mol.%, 2.0 mol.%, 10. 0 mol.%)/Er3+ (fixed at 1.0 mol.%). This detailed study of the up-conversion processes allowed us to identify the dominant up-conversion mechanisms in Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals. 相似文献
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孙金超 《武汉冶金管理干部学院学报》2021,(2):44-45,48
教学质量评价是当前高等教育改革的重要课题之一,是提升高校应用型人才培养质量的基本保障.现阶段高校教学质量综合评价体系还存在重管理而轻发展、重教情而轻学情、重结果而轻过程、重总结而轻整改等问题.因此,有必要立足新时期,从价值取向、评价设计、评价实施、评价反馈四个方面,探讨教学质量综合评价体系的改进策略,以充分发挥教学质量... 相似文献
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为研究含异长双裂纹试件中次裂纹偏置对聚甲基丙烯酸甲酯(PMMA)试件动态冲击断裂行为的影响,采用数字激光动态焦散线系统和冲击加载平台进行动态焦散线试验.记录了裂纹的焦散斑图像和主裂纹的起裂时间.讨论了裂纹缺陷对主裂纹的起裂时间、裂纹扩展最大速度和裂纹尖端动态应力强度因子的影响.试验结果表明:β对主裂纹起裂时间的早晚和主裂纹扩展速度最大值产生了明显的影响,而且这种影响效应会由于主次裂纹位于PMMA试件中线的不同位置而表现出明显的差异性.主裂纹应力强度因子变化规律相似,但达到K最大值的时间表现出了差异. 相似文献
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