Feature		Characteristics
Space	PCA	Reduced dimension of the origin features with PCA method.
	Magnitude	Down-sampled values of the curve’s magnitude M. The maximum magnitude. Down-sampled values of the normalized magnitude M/max (M). Mean values of the magnitude.
	Derivative	Down-sampled values of the curve’s derivative D. The maximum and minimum derivative.
	Second derivative	The maximum and minimum second derivative in both the injection and purge stage.
	Integral	The integral of the five intervals of the curve; the intervals are the same with the difference feature.
	Slope	The slope of the five intervals of the curve; the intervals are the same with the difference feature.
	Phase Feature	The phase feature is proposed in [ 44 ]. First, the response is transformed to the phase space, which is spanned by its magnitude and derivative. Then, the phase feature is defined as $\int_{M (t_{i})}^{M (t_{i + 1})} D d M$
Frequency	FFT	Fast Fourier tranformation
Frequency	Wavelet	Wavelet transformation