Search

• 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]

Magnetic lenses can effectively reduce the fiber diameter and whipping-circle width to control the random behavior of electrospinning. Although the axisymmetric magnetic lens for electrostatic spinning have several potential applications, the effect of its pole-piece structure on the electrostatic spinning process has not been adequately discussed. In this study, we explored the influence of changing the pole piece structure of the magnetic lens on the electrospinning process using experimental and numerical simulation methods. The results showed that for a 12 wt% polyacrylonitrile (PAN) solution, when the applied voltage was 15 kV, the feed rate was 1 mL/h, and current of the magnetic lens was 1 A, the gap width of the magnetic lens had a notable effect on the fiber deposition efficiency of the electrostatic spinning range of the magnetic lens. Appropriately reducing the gap width in the range of 1–10 mm can effectively reduce the deposition range of the fibers and improve fiber film thickness. Furthermore, when the angle of α is 45°, it exerts the most significant effect on the electrostatic spinning spray range and deposition efficiency, and the fiber film thickness and average fiber diameter attain their highest values. When the angle of α increases or decreases from 45°, the fiber film thickness and fiber diameter both show a decreasing trend. A change in the magnetic lens structure can effectively change the ejection range and fiber diameter during electrostatic spinning, which shows great potential in the field of nanofiber production. [Display omitted] • Changing the magnetic lens structure can control the ejection range and fiber diameter during electrostatic spinning. • Study investigates the impact of magnetic lens pole-piece structure on electrospinning using experiments and simulations. • Optimal gap width (1–10 mm) enhances fiber deposition efficiency and film thickness. • Angle α of 45° maximizes electrostatic spinning range, deposition efficiency, fiber film thickness, and diameter. [ABSTRACT FROM AUTHOR]

The homebuilt traditional electrostatic spinning apparatus was equipped with a silicone rubber heating plate and a magnetic lens to produce polyacrylonitrile (PAN) nanofiber films. The PAN nanofibers used in this experiment were examined using a scanning electron microscope (FE-SEM) as well as other characterization tools to determine their morphology, diameter, crystallinity, thickness, and mechanical characteristics. The experimental results showed that the combined effect of two parameters, the temperature of the receiver plate and the magnetic field generated by the magnetic lens let to the production of fibers with a smaller diameter (308 nm). The magnetic field generated by the magnetic lens increased the thickness of the nanofiber membrane, whereas the temperature decreased the diameter of the nanofibers. The combined effect of the temperature and magnetic fields increased the thickness of the nanofiber membrane. The combined effect of the aforementioned parameters led to a nanofiber crystallinity of 70.72%, which was higher than the average crystallinity generated by the individual impact of the said parameters. The mechanical characteristics also improved significantly with an increase in receiver plate temperature. In conclusion, the combined effect of the temperature of the receiver plate and the magnetic field generated by the magnetic lens improved the performance of the PAN nanofibers and was more significant than their independent impact. A foundation for the preparation of high-performance filtration membranes was laid and the results paved the way for industrializing the process. [Display omitted] [ABSTRACT FROM AUTHOR]

The homebuilt traditional electrostatic spinning apparatus was equipped with a silicone rubber heating plate and a magnetic lens to produce polyacrylonitrile (PAN) nanofiber films. The PAN nanofibers used in this experiment were examined using a scanning electron microscope (FE-SEM) as well as other characterization tools to determine their morphology, diameter, crystallinity, thickness, and mechanical characteristics. The experimental results showed that the combined effect of two parameters, the temperature of the receiver plate and the magnetic field generated by the magnetic lens let to the production of fibers with a smaller diameter (308 nm). The magnetic field generated by the magnetic lens increased the thickness of the nanofiber membrane, whereas the temperature decreased the diameter of the nanofibers. The combined effect of the temperature and magnetic fields increased the thickness of the nanofiber membrane. The combined effect of the aforementioned parameters led to a nanofiber crystallinity of 70.72%, which was higher than the average crystallinity generated by the individual impact of the said parameters. The mechanical characteristics also improved significantly with an increase in receiver plate temperature. In conclusion, the combined effect of the temperature of the receiver plate and the magnetic field generated by the magnetic lens improved the performance of the PAN nanofibers and was more significant than their independent impact. A foundation for the preparation of high-performance filtration membranes was laid and the results paved the way for industrializing the process. [Display omitted] [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]