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Transient thermal impedance of GaN-based high-power white light emitting diodes (LEDs) is created using a thermal transient tester. An electro-thermal simulation shows that LED junction temperature (JT) rises to a very low degree under low duty cycle pulsed current. At the same JT, emission peaks are equivalent at pulsed and continuous currents. Moreover, the difference in peak wavelength when a LED is driven by pulsed and continuous currents initially decreases then increases with increasing pulse width. Thus, selecting an appropriate pulse width decreases errors in JT measurement. 相似文献
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为验证红外地球敏感器扫描电机轴承油润滑设计寿命是否满足5年的指标要求. 首先,通过理论计算扫描电机轴承润滑油初始油量能否满足电机运行寿命需求. 其次,通过扫描电机1:1地面寿命试验验证此油润滑方式的可靠性,寿命试验结束后对滚动轴承进行了显微观测,并对轴承进行了剖解分析. 扫描电机在寿命试验期间运转正常,常温条件下电机电流稳定在20~40 mA,扫描电机累计运转时间已超过8年. 轴承显微分析结果表明:内、外圈滚道和滚珠表面状态良好,轴承内圈运动副表面的面粗糙度从0.416 μm变化为0.512 μm,无明显点蚀、磨损现象产生,润滑状态良好. 扫描电机寿命试验结果验证了含油保持架外加储油器供油的油润滑方式可满足电机轴承5年寿命要求,为其他处于边界润滑工况下的空间运动部件长寿命设计提供参考依据. 相似文献
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