Wind power.
I'm interested how a fan blade that has no vibration in a wind tunnel (at design time), moved Smoothly toward the wind (who's rate of speed is limited by many factors), can cause vibration. (i assume the start of movement is not abrupt, since most electrical motors cannot do that - and use of those that can are unlikely used because they would cause a sudden force which was not cost effective or intended)
Is there a URL of a site showing actual vibration data of wind generators which shows why a front facing powered pivot (not a rear facing wind controlled one) would be used, and exactly what vibrations are detected during tests that are objectionable?
