Blind source extraction of acoustic emission signals for rail cracks based on ensemble empirical mode decomposition and constrained independent component analysis

•Constrained independent component analysis is proposed to extract sequential sources.•Kurtosis and waveform factor are added as constraints to retrieve specified source.•Ensemble empirical mode decomposition is employed to produce sufficient observations.•The on-site raw signal is acquired from the real operating environment of railway.•The proposed method is verified to extract cracks in single-channel noisy signal.