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输送固体颗粒的临界流速是疏浚课教学中重要的知识点,但课堂讲授反映平淡。本文结合教育部疏浚技术工程中心现有的透明输送实验台,对在疏浚课教学中开设临界流速实验课程进行了介绍,将理论性强的课堂知识点移植到实验中来讲授,让学生直观地观察到管内流动状态,主动查找相应的临界流速数学模型进行校核,化被动接受为主动获取,提高了课堂效率和学生的积极性,对类似的教学有一定的推广价值。 相似文献
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The colloids of Eu(DBM)3 and ultrafine particles Eu(DBM)3 were perpared. The particle sizes determined by X-ray and by TEM measurements were in 7-30nm range. Their UV absorption and fluorescence spectra were compared with each other and with those of the solid sample. It was shown that the 5D1→7 F1,2 transition was observed in the colloids of Eu(DBM)3 at room temperature. The increase of the excited-state S1 and T1 energy, the peak positions of UV absorption shifted to shorter wavelength, the changes of the absoprtion coefficient with decreasing size were observed. 相似文献
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