min.size:  The minimum number of observations between change points
基本上是基於breakout detection algorithm
請參考：https://blog.twitter.com/2014/breakout-detection-in-the-wild
1. 均值移動
2. 逐步上升／下降
所以min.size會決定你偵測的窗口長度，改變小則會看到許多breakout，反之亦然。
beta: A real numbered constant used to further control the amount of penalization.
This is the default form of penalization, if neither (or both) beta or (and) percent are supplied this argument will be used.
The default value is beta=0.008.
beta基本上是對錯誤偵測的處罰，beta 值越大，很明顯的anomaly才會顯現，但會壓抑其它真的但教部明顯的。應該是個try and error 的參數。