自由度和标准

多自由度可调节光学标准平面镜是专业为大型光学镜片调整设计的电动万向式镜架,可满足最大0.62米反射镜安装调整,非常适合天文光学和大型高功率激光实验系统使用。

ASTM D2732 塑料薄膜和薄板的自由线性热收缩率的标准试验方法测试要求在试样纵向和横向各画一条对称轴作标记,并标明纵、横向,将试样平放入两框架间,接着,迅速浸入120士2℃的恒温介质中自由收缩,20 s后取出,浸入备用的常温浴中,冷却5 s后取出试样,水平静置,在30 min内测量纵横对称轴尺寸。精确到1 mm,并记录测量数据

A novel support mechanism for a wind tunnel model is designed, built, and demonstratedon an aerodynamic platform undergoing dynamic maneuvers, tested with periodic motions up to20 Hz. The platform is supported by a 6-DOF (six degrees of freedom) traverse that utilizes eightthin wires, each mounted to a servo motor with an in-line load cell to accurately monitor or controlthe platform motion and force responses. The system is designed such that simultaneous control ofthe servo motors effects motion within 50 mm translations, 15 pitch, 9 yaw, and 8 roll atlower frequencies. The traverse tracks a desired trajectory and resolves the induced forces on theplatform at 1 kHz. The effected motion of the platform is measured at 0.6 kHz with a motion capturesystem, which utilizes six near-infrared (NIR) cameras for full spatial and temporal resolution of theplatform motion, which is used for feedback control. The traverse allows different platform modelgeometries to be tested, and the present work demonstrates its capabilities on an axisymmetric bluffbody. Programmable timed outputs are synchronized relative to the model motion and can be usedfor triggering external systems and processes. In the present study, particle image velocimetry (PIV)is used to characterize the realized wakes of the platform undergoing canonical motions that areeffected by this new wind tunnel traverse.