find_peak

代码说明：

  从曲线中检测到其峰值：先利用二次求导得到所有凸点，设置门限，去除过低的凸点，然后利用滑动窗的方法，在凸点中求得满足峰值要求的点(Detected from the curve to its peak: the first use of the second derivative method to get all the bumps, set the threshold too low to remove the bumps, and then use a sliding window, obtained in a bump to meet peak requirements of point)