Integration method of compressed sensing with variational mode decomposition based on gray wolf optimization and its denoising effect in mud pulse signal.

The continuous wave mud pulse transmission holds great promise for the future of downhole data communication. However, significant noise interference during the transmission process poses a formidable challenge for decoding. In particular, effectively eliminating random noise with a substantial amplitude that overlaps with the pulse signal spectrum has long been a complex issue. To address this, an enhanced integration algorithm that merges variational mode decomposition (VMD) and compressed sensing (CS) to suppress high-intensity random noise is proposed in this paper. In response to the inadequacy of manually preset parameters in VMD, which often leads to suboptimal decomposition outcomes, the gray wolf optimization algorithm is designed to obtain the optimal penalty factor and decomposition mode number in VMD. Subsequently, the optimized parameter combination decomposes the signal into a series of intrinsic modes. The mode exhibiting a stronger correlation with the original signal is retained to enhance signal sparsity, thereby fulfilling the prerequisite for compressed sensing. The signal is then observed and reconstructed using the compressed sensing method to yield the final signal. The proposed algorithm has been compared with VMD, CS, and CEEMD; the results demonstrate that the method can enhance the signal-noise ratio by up to ∼20.55 dB. Furthermore, it yields higher correlation coefficients and smaller mean square errors. Moreover, the experimental results using real field data show that the useful pulse waveforms can be recognized effectively, assisting surface workers in acquiring precise downhole information, enhancing drilling efficiency, and significantly reducing the risk of engineering accidents.

Influence of O2 Flow Rate on the Properties of Ga2O3 Growth by RF Magnetron Sputtering.

The influence of the O2 flow rate on the properties of gallium oxide (Ga2O3) by RF magnetron sputtering was studied. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmittance spectra, and photoluminescence (PL) spectra have been employed to study the Ga2O3 thin films. With the increase in oxygen flow rate, both the crystal quality and luminescence intensity of the Ga2O3 samples first decrease and then enhance. All these observations suggested that the reduction in the oxygen defect density is responsible for the improvement in the crystal quality and emission intensity of the material. Our results demonstrated that high-quality Ga2O3 materials could be obtained by adjusting the oxygen flow rate.

Characterization of ultrathin InSb nanocrystals film deposited on SiO2/Si substrate.

Recently, solid-phase recrystallization of ultrathin indium antimonide nanocrystals (InSb NCs (films grown on SiO2/Si substrate is very attractive, because of the rapid development of thermal annealing technique. In this study, the recrystallization behavior of 35 nm indium antimonide film was studied. Through X-ray diffraction (XRD) analysis, it is demonstrated that the InSb film is composed of nanocrystals after high temperature rapid thermal annealing. Scanning electron microscopy shows that the film has a smooth surface and is composed of tightly packed spherical grains, the average grain size is about 12.3 nm according to XRD results. The optical bandgap of the InSb NCs film analyzed by Fourier Transform infrared spectroscopy measurement is around 0.26 eV. According to the current-voltage characteristics of the InSb NCs/SiO2/p-Si heterojunction, the film has the rectifying behavior and the turn-on voltage value is near 1 V.