共查询到18条相似文献,搜索用时 78 毫秒
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利用视频分析软件Tracker的自动追踪功能,有效地追踪复摆的振动轨迹,描绘出振动的位移-时间曲线,拟合后得到角速度,并计算出振动周期,进而用等效摆长法和直线拟合法计算出重力加速度. 相似文献
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本文计及纵光学声子的色散,计算了激子的结合能,发现计及声子色散所导出的激子有效势,对计算激子的结合能有所改进. 相似文献
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EVALUATION OF WHOLE-BODY VIBRATION IN VEHICLES 总被引:3,自引:0,他引:3
G.S. PADDANM.J. GRIFFIN 《Journal of sound and vibration》2002,253(1):195-213
The vibration in 100 different vehicles has been measured, evaluated and assessed according to British Standard BS 6841 (1987) and International Standard ISO 2631 (1997). Vibration was measured in 14 categories of vehicle including cars, lift trucks, tractors, lorries, vans and buses. In each vehicle, the vibration was measured in five axes: vertical vibration beneath the seat, fore-and-aft, lateral and vertical vibration on the seat pan and fore-and-aft vibration at the backrest. The alternative methods of evaluating the vibration (use of different frequency weightings, different averaging methods, the inclusion of different axes, vibration dose values and equivalent r.m.s. acceleration) as defined in the standards have been compared. BS 6841 (1987) suggests that an equivalent acceleration magnitude is calculated using vibration measured at four locations around the seat (x -, y -, z -seat and x -backrest); ISO 2631 (1997) suggests that vibration is measured in the three translational axes only on the seat pan but only the axis with the most severe vibration is used to assess vibration severity. Assessments made using the procedure defined in ISO 2631 tend to underestimate any risks from exposure to whole-body vibration compared to an evaluation made using the guidelines specified in BS 6841; the measurements indicated that the 17 m/s1.75 “health guidance caution zone” in ISO 2631 was less likely to be exceeded than the 15 m/s1.75 “action level” in BS 6841. Consequently, ISO 2631 “allows” appreciably longer daily exposures to whole-body vibration than BS 6841. 相似文献
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