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• The improved VMD and DWT are combined to denoise and reconstruct the signal under strong noise without a reference. • The selection of wavelet function and transform level in DWT is optimized by Shannon entropy to denoise the signal without a reference. • The RAPID and the CNN are used to achieve spatial localization and visualization of the composite delamination. In this paper, a damage spatial imaging approach based on novel signal extraction is suggested to reconstruct the Lamb wave response signal under strong noise and realize the spatial localization of damage. First, the Variable Mode Decomposition (VMD) parameters are optimized by the improved Grey Wolf optimization method (IGWO) to decompose the response signal. To rebuild the response signal, the correlation coefficient is used to choose the optimal modal component and the residual. To give the best wavelet function and transform level for adaptive denoising of the reconstructed signal without a reference signal, an enhanced Discrete Wavelet Transform (DWT) based on Shannon entropy is proposed. To achieve damage localization imaging, a damage spatial localization model is built utilizing a reconstruction algorithm for probabilistic inspection of damage (RAPID) approach and a convolutional neural network (CNN). The suggested method may successfully increase the signal-to-noise ratio (SNR) of the reconstructed response signal and lower the error of spatial localization under strong noise through experiments. The spatial localization of composite damage using Lamb wave under strong noise is expanded in this paper. [ABSTRACT FROM AUTHOR]

The three primary reactions in metal-air batteries and electrochemical hydrolysis are the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). Therefore, it is crucial to develop efficient low-cost trifunctional catalysts. In this study, we design a self-supported electrocatalyst with hierarchical nanostructure, in which the bamboo-like nitrogen doped carbon nanotubes (NCNTs) encapsulated CoFe nanoparticles (CoFe NPs) in-situ anchored on nanoflower like CoFe 2 O 4 via chemical vapor deposition. Strikingly, the resulting catalysts CoFe@NC/CoFe 2 O 4 /IF demonstrate exciting trifunctional catalytic performance, overpotential of 66 mV and 185 mV for HER and OER at current densities of 10 mA cm−2, and a half-wave potential of 0.852 V for ORR, respectively. In addition, the maximum power density of the Zinc-air batteries (ZABs) assembled with CoFe@NC/CoFe 2 O 4 /IF as the cathode electrode is 134.5 mW cm−2; and the overall water splitting requires only a voltage of 1.50 V at a decomposition current density at 10 mA cm−2. This method provides a new strategy for trifunctional electrocatalysts and offers a promising approach for self-driven water electrolysis devices. • Self-supported electrocatalysts with multilevel nanostructures. • The catalyst exhibits remarkable HER, OER and ORR performance. • A variety of active species cooperatively enhance catalytic activity. • It can be applied to ZABs and self-driven overall water splitting. [ABSTRACT FROM AUTHOR]