Since the flight test data are of time domain, it needs to be converted into frequency domain by FFT method. Then it can be used to identify the system.

由于飞行试验数据是时域数据，使用这种方法需要使用FFT的方法将实测的时域数据转换成频域数据后再进行辨识。

youdao

youdao

Since the day of Heidi's attempted flight a great change had come over the child.

自从海蒂试图逃跑的那天起，这个孩子发生了很大的变化。

youdao

Since the emergency landing of flight fifteen forty-nine, special radars have received a lot of attention.

VOA: special.2009.04.01

Many pilots have flown around the world since Wiley Post made his famous flight.

VOA: special.2009.03.18

Despite billions being spent on aviation security since 911, security was breached on Christmas Day as the trans-Atlantic flight from Amsterdam approached Detroit.

VOA: standard.2009.12.28

The fate of the three Canadian crew members aboard the aircraft had been unknown since the the flight went missing Wednesday.

CNN: 3 believed dead after plane wreckage found in Antarctica

Or, since the first flight will be from Toronto toVancouver, to the Roots Lodge on Vancouver Island.

FORBES: Reach For The Sky

Blackpool - whose average home crowd of 8, 611 was the second-lowest in the Championship this season - will be the smallest club in the top flight since the formation of the Premier League in 1992.

BBC: Blackpool play-off win will boost whole town - Holloway