井下综采工作面噪声污染情况严重,长期危害现场作业人员的生理及心理健康。为了充分了解综采工作面噪声场的具体分布情况,本文利用COMSOL Multiphysics软件对煤矿井下综采工作面的噪声场进行模拟研究,并结合现场噪声计权声压级实测进行...井下综采工作面噪声污染情况严重,长期危害现场作业人员的生理及心理健康。为了充分了解综采工作面噪声场的具体分布情况,本文利用COMSOL Multiphysics软件对煤矿井下综采工作面的噪声场进行模拟研究,并结合现场噪声计权声压级实测进行对比分析,结果表明:1)通过数值模拟获得了井下综采工作面内多组噪声场的分布云图;2)综采工作面噪声场计权声压级介于40~110 d B,噪声级别较高点集中于采煤机、进风口、出风口区域,噪声场在采煤机处取得最大值110 d B;3)井下现场实测验证表明,综采工作面内采煤机处于不同工况位置条件下其噪声场的模拟值与试验值基本吻合,该数值模拟方法可用于井下综采工作面噪声场分布规律的研究。展开更多
噪声是煤矿井下主要危害,对人体视觉系统的影响不容忽视。为了提高暴露在噪声环境中工人的视觉认知能力,进而减少人因事故的发生,针对视觉认知随噪声暴露时间的变化进行研究,利用Eye Link II眼动仪采集被试者的平均注视时间、平均眼跳...噪声是煤矿井下主要危害,对人体视觉系统的影响不容忽视。为了提高暴露在噪声环境中工人的视觉认知能力,进而减少人因事故的发生,针对视觉认知随噪声暴露时间的变化进行研究,利用Eye Link II眼动仪采集被试者的平均注视时间、平均眼跳幅度和眼跳次数3个眼动指标来衡量视觉认知能力随着综采工作面噪声暴露时间的变化。结果表明：1）噪声能够使视觉注意力下降,对视觉认知效率的影响不显著,对视觉辨识能力的影响较复杂;2）噪声在0-10 min和40-55 min时间段对视觉注意力影响较严重,在0-15 min和50-80 min时间段对视觉辨识能力影响较严重;3）被试者随时间变化出现视觉性疲劳后,噪声可轻微提高视觉认知效率和视觉辨识能力。展开更多
AlGaN/GaN high electron mobility transistors （HEMTs） were irradiated by 256 MeV 127I ions with a fluence up to 1 × 10^10 ions/cm2 at the HI-13 heavy ion accelerator of the China Institute of Atomic Energy. Bot...AlGaN/GaN high electron mobility transistors （HEMTs） were irradiated by 256 MeV 127I ions with a fluence up to 1 × 10^10 ions/cm2 at the HI-13 heavy ion accelerator of the China Institute of Atomic Energy. Both the drain current ld and the gate current Ig increased in off-state during irradiation. Post-irradiation measurement results show that the device output, transfer, and gate characteristics changed significantly. The saturation drain current, reverse gate leakage current, and the gate-lag all increased dramatically. By photo emission microscopy, electroluminescence hot spots were found in the gate area. All of the parameters were retested after one day and after one week, and no obvious annealing effect was observed under a temperature of 300 K. Further analysis demonstrates that swift heavy ions produced latent tracks along the ion trajectories through the hetero-junction. Radiation-induced defects in the latent tracks decreased the charges in the two-dimensional electron gas and reduced the carrier mobility, degrading device performance.展开更多
文摘井下综采工作面噪声污染情况严重,长期危害现场作业人员的生理及心理健康。为了充分了解综采工作面噪声场的具体分布情况,本文利用COMSOL Multiphysics软件对煤矿井下综采工作面的噪声场进行模拟研究,并结合现场噪声计权声压级实测进行对比分析,结果表明:1)通过数值模拟获得了井下综采工作面内多组噪声场的分布云图;2)综采工作面噪声场计权声压级介于40~110 d B,噪声级别较高点集中于采煤机、进风口、出风口区域,噪声场在采煤机处取得最大值110 d B;3)井下现场实测验证表明,综采工作面内采煤机处于不同工况位置条件下其噪声场的模拟值与试验值基本吻合,该数值模拟方法可用于井下综采工作面噪声场分布规律的研究。
基金supported by the National Natural Science Foundation of China(Grant No.61204112)
文摘AlGaN/GaN high electron mobility transistors （HEMTs） were irradiated by 256 MeV 127I ions with a fluence up to 1 × 10^10 ions/cm2 at the HI-13 heavy ion accelerator of the China Institute of Atomic Energy. Both the drain current ld and the gate current Ig increased in off-state during irradiation. Post-irradiation measurement results show that the device output, transfer, and gate characteristics changed significantly. The saturation drain current, reverse gate leakage current, and the gate-lag all increased dramatically. By photo emission microscopy, electroluminescence hot spots were found in the gate area. All of the parameters were retested after one day and after one week, and no obvious annealing effect was observed under a temperature of 300 K. Further analysis demonstrates that swift heavy ions produced latent tracks along the ion trajectories through the hetero-junction. Radiation-induced defects in the latent tracks decreased the charges in the two-dimensional electron gas and reduced the carrier mobility, degrading device performance.
