Application Of Empirical Mode Decomposition In The Coulostatical Measuration Of Metal Corrosion

The research of metal corrosion has important meaning in the aspect of marine project, the petroleum platform of well drilling, the structural thing of reinforced concrete and so on. To do this job, the mensuration of corrosion speed is very important. Along with the development of electronic industry, the corrosion measure technique using electrochemical principle has progressed at a rapid rate.The coulostatic technique adopts the advanced electronics technique.In the case of a coulostatic perturbation to the relevant corrosion system in a cutty time, a potential transient is recorded instantly after the application of a small known amount of charge. By analyzing the coulostatically-induced transient, the electrical parameters of some predefined network models can be found.However, the signals obtained by compute are affected by noise drastically since the electrode response signal induced by the coulostatic perturbations is faint. The noises are not only from experimental system but also the system of gaining signal. They degrades the accuracy and precision of the analysis and detection. Signal de-noising is therefore highly desirable.The traditional FIR method is using FIR low-pass filter since the noises of coulostatically-induced transients are mainly high-frequency noise and 50Hz noise. But coulostatically-induced transients also have high-frequency components, it will be lost if coulostatically-induced transients is filtered by FIR low-pass filter and the filtering result will be distort. So empirical mode decomposition will be the filtering method in this paper.The empirical mode decomposition is a new de-noising method based on time-frequency multi-resolution analysis which is superior to the classical way relies on the Fourier transform. The method is based on local intrinsic time scales, the IMFs are derived from the original signal, the intrinsic time scales are the interval between nearest minima or maxima.Usually the FIR low-pass filter is the method to filter the high-frequency noise and 50Hz noise of coulostatically-induced transients. This paper analyses the defect of traditional FIR low-pass filter for the de-noising of coulostatically-induced transients from theory and simulating experiment, the empirical mode decomposition will be the filtering method in this paper, the de-noising criterion for coulostatically-induced transients using the empirical mode decomposition is presented and studied. The simulating and real experiments reveal the empirical mode decomposition is superior to the FIR method. The empirical mode decomposition can get the good de-noising results both in the time domain and frequency domain. It is effective on the analysis and processing of nonlinear and non-stationary signals.