The penalty parameter (c) and kernel parameter (g) contained in Support Vector Machine (SVM) cannot be adaptively selected according to actual samples, which results in low classification accuracy and slow convergence speed. A novel sparrow search algorithm was used to optimize the parameters of SVM classifier. Firstly, an improved ensemble empirical mode decomposition (MEEMD) method was used to decompose non-stationary and nonlinear vibration signals, and the eigenmode function (IMF) was obtained by removing abnormal signals from the original signals through permutation entropy, and the sample entropy was extracted. Finally, a fault diagnosis model based on SSA-SVM is constructed, and the high recognition rate and effectiveness of this method are proved by simulation and experimental data analysis.

The digital economy and ecological environment are two major issues related to high-quality economic development. Scholars have not yet reached a unified conclusion about the link between the digital economy and pollution emissions, and the impact mechanism of the former on the latter needs further study. Using data from 278 Chinese cities from 2010 to 2019, this research employs coupling coordination analysis, fixed effect analysis and mediation analysis to examine the heterogeneous impact mechanisms of the expansion of the digital economy on urban pollution reduction from many angles. It discovers that, first, the growth of the digital economy has decreased the discharge of urban pollutants overall. Second, the impact mechanisms of the digital economy are heterogeneous. From a regional perspective, industrial structure supererogation plays an intermediary role in the relationship between digital economy development and pollution reduction in the eastern and central regions, but the mediating effect is not significant in the western and northeastern regions. In terms of the city development level, industrial structure supererogation has significantly mediated the relationship between the growth of the digital economy and the reduction of pollution in first- and second-tier cities, but this mediating effect is not significant in third-tier and other cities. Third, the above conclusions are still valid after the robustness test is carried out using instrumental variable estimation, replacement of the estimation method, and replacement of explanatory variables. This study is a useful contribution to research on the effects of the digital economy and the factors influencing pollution reduction. The results advance the study of the digital economy and also have practical implications for improving China’s ecological environment and fostering high-quality economic growth. Finally, we provide policy suggestions for the coordinated promotion of the digital economy’s development, industrial structure supererogation and environmental pollution reduction.

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This paper examines a three-phase grid-connected photovoltaic inverter using LCL technology. Circuit for a full-bridge inverter with three phases and a filter of type LCL are used, and the control strategy consisting of two closed-loop loops is used to remove the effects caused by harmonics on the system. Finally, the simulation and analysis are carried out by MATLAB software to express the possibility of inverter system operation in a more intuitive way, such as a waveform diagram, to verify the rationality of the paper.

We investigate the effect of ownership structure on banks’ capital buffers with a method of System GMM, for a sample of main commercial banks in China. The increase of ownership concentration can promote the buildup of capital buffers, while implicit guarantee from government can reduce this effect for the systemically important banks. The relative lower ratio of interbank deposit to total deposits weaken the supervision from peer banks for the accumulation of capital buffers. Adequately increase the ratio of major shareholders, accelerate the development of interbank deposit market and reduce government implicit guarantees are very essential for Chinese financial stability.