Study on De-Noising of Internal Leakage Acoustic Emission Signal in Hydraulic Slide Valves Based on CEEMDAN-MI-IncrEn-NLM

Aiming at solving problems of low signal-to-noise ratio (SNR) and difficulty in de-noising of internal leakage signals of hydraulic slide valves, this paper proposes a denoising method based on CEEMDAN-MI-IncrEn-NLM. First, signals are decomposed by CEEMDAN (Complete ensemble empirical mode decomposition with adaptive noise) approach respectively. Noise signals are distinguished from noise-dominant signals by MI(mutual information) method, and the noise signals are eliminated. Then, IncrEn (increment entropy) is used to distinguish noise-dominant signals and internal leakage signals. Finally, NLM (Non-local means) algorithm is used to filter noise of noise-dominant signals and reconstruct internal leakage signals. Results show that the method in severe noise-contaminated environment can effectively improve regular signals' SNR around 19 dB at maximum, and it can filter out gaussian white noise while reserving valid signals of internal leakage as well.