As for China's RMB, they really didn't start allowing it to quasi-float vs. the $ till around 2011.

http://bigcharts.marketwatch.com/advchart/frames/frames.asp?show=&insttype=Currency&symb=usdcny&x=37&y=9&time=20&startdate=1%2F4%2F1999&enddate=2%2F9%2F2016&freq=3&compidx=aaaaa%3A0&comptemptext=&comp=none&ma=5&maval=9&uf=0&lf=268435456&lf2=2&lf3=4&type=4&style=320&size=4&timeFrameToggle=false&compareToToggle=false&indicatorsToggle=false&chartStyleToggle=false&state=11

The issue with them attempting (and failing) to control a soft landing in the stock market is a different matter than their capital controls they use in an attempt to protect their stock exchanges.  

These stock market operations are similar to those used by many US exchanges as well  http://www.nasdaqtrader.com/trader.aspx?id=CircuitBreaker.  Not exactly relevant to the discussion of our economics model as there is no autonomous entity within these exchanges serving to smooth out the volatility.