Before revision:  However, it still suffers from issues such as inconsistency over short-length signals and its tolerance parameter r, susceptibility to signal amplitude changes and insensitivity to self-similarity of time series.
After revision:  However, their relationship with the Hurst exponent as a measure of self-similarity has not been deeply studied. Also, they still suffer from susceptibility to signal amplitude changes and insensitivity to self-similarity of time series.