Infrared to ultraviolet upconversion luminescence in Nd doped nano-glass-ceramic

Nd^3＋ doped transparent oxyfiuoride glass ceramic containing β-YF3 nanocrystals was prepared and the upconversion luminescence behaviors of Nd^3＋ in the precursor glass and glass ceramic were investigated. Under 796 nm laser excitation, ultraviolet upconversion emissions of Nd^3＋ ions at 354 nm （^4D3/2→^4I11/2） and 382 nm （^4D3/2→^4I11/2） were observed at room temperature. Power dependence analysis demonstrated that three-photon upconversion processes populated the ^4D3/2 excited state. In comparison with those of the precursor glass, the ultraviolet emissions were enhanced by a factor of 500 in the glass ceramic, which was attributed to the change in the ligand field of Nd^3＋ ions and the decrease in phonon energy because of the partition of Nd^3＋ ions into the β-YF3 nanocrystals after crystallization.     

高压齿轮泵污染磨损的寿命模型研究与验证

工程应用案例中常常遇到齿轮泵的实际使用寿命远低于开发设计中的预期寿命情况。针对这一现象,提出了固体颗粒在液压油污染条件下的敏感度概念,并建立齿轮泵在颗粒污染下的预测寿命模型。以某轴向补偿外啮合齿轮泵为研究对象,设计一台关于齿轮泵污染敏感度试验装置,系统中输入一定浓度尺寸的固体颗粒,得到分布颗粒的污染敏感度参数,依据计算固体颗粒在NAS1638标准下的分布情况,获得泵在不同污染等级下的磨损预测寿命。同时绘制出被试泵在NAS10级污染下磨损寿命为2000 h的污染耐受度曲线。研究结果具有一定的工程应用价值,能够定量分析和比较被试泵的污染耐受性、预测泵在不同颗粒污染等级下的性能变化规律和污染磨损寿命,可为高污染耐受泵的设计提供参考。     

基于PBL的电磁场与电磁波课程教学改革探索

“电磁场与电磁波”课程作为电子信息类专业的专业基础课,教学内容具有理论性强、公式繁杂、概念抽象等特点,难教亦难学。根据该课程教学内容的特点,对该课程的教学方法进行创新性的探索,提出PBL教学法并于课堂实践,致力于激发学生的学习热情,增强学生的学习自觉性和积极性,提升课堂的教学效果。     

高效上转换白光发射透明玻璃陶瓷

通过在含正交结构氟化钇纳米晶的透明玻璃陶瓷中共掺Er/Tm/Yb或Ho/Tm/Yb稀土离子,在976nm激光激发下,可以获得明亮的室温上转换白光发射,其色度坐标与标准的等能白光十分接近,能量转换效率约为0.1%.