Yongqi Cai

Rapid testing of cement raw meal plays a crucial role in the cement production process, so there is an urgent need for a fast and accurate testing method. In this paper, a method based on the Savitzky-Golay (SG) smoothing and sample set partitioning based on joint x-y distance (SPXY) spectral data pre-processing is proposed to improve the accuracy of the laser-induced breakdown spectroscopy (LIBS) technique for quantitative analysis of cement raw meal components. Firstly, the spectral data is denoised by SG smoothing, which effectively reduces the noise and baseline variations in the spectra. Then, the denoised data is divided into sample sets by combining the SPXY sample division method, which improves the efficiency of data analysis. Finally, the delineated data set is modeled for quantitative analysis by a back-propagation (BP) neural network. Compared to the modeling effect of the four oxide contents of CaO, SiO₂, Al₂O₃, and Fe₂O₃ in the Hold-Out method, the correlation coefficient (R) was improved by 26%, 10%, 17%, and 4%, respectively. The root mean square error (RMSE) was reduced by 47%, 33%, 43%, and 21%, respectively. The mean absolute percentage error (MAPE) was reduced by 63%, 60%, 36%, and 51%, respectively. The results show that there is a significant improvement in the model effect, which can effectively improve the accuracy of quantitative analysis of cement raw meal composition by LIBS. This is of great significance for the real-time detection of cement raw meal composition analysis.

A scheme to enhance the optical delay in Rydberg atoms is proposed. In the linear case, the optical delay in a four-level system can be significantly enhanced compared to that of the three-level system. However, the width of the transparent window will decrease with an increase in the optical delay. In the nonlinear case, the nonlinear dispersion becomes steep around the transparency window. The enhanced cross-Kerr nonlinearity mainly contributes to the effective dispersion, which dramatically increases the optical delay. The simulation result shows that the optical delay of the system could be enhanced tens of times; moreover, the wide transparency window remains. So the delay-bandwidth product could be significantly improved due to nonlinear dispersion. We further examine Gaussian pulse propagation in the Rydberg atoms.

An efficient scheme for a microwave (MW) receiver is proposed based on the active Raman gain (ARG) in Rydberg atoms. The 87 R b atoms are excited to the Rydberg state ( 53 D 5 / 2 ) , and the gain spectrum has a single gain peak. The MW field is resonant with the Rydberg transition ( 53 D 5 / 2 → 54 P 3 / 2 ) , resulting in a split in the gain spectrum. The frequency splitting of two peaks depends linearly on the MW field strength. The distortion and attenuation of the probe field are reduced, due to the system's operating in the stimulated Raman emission mode. Simulation results show that the fidelity of MW communication based on the Rydberg atomic ARG scheme is improved by at least 10 times compared to that based on an electromagnetically induced transparency scheme, and the system seems more robust to amplitude modulation signals with different modulation depths.