Innovative rapid liquid concentration measurement based on thermal lens effect and machine learning.

This study addresses the critical need for rapid and online measurement of liquid concentrations in industrial applications. Although the thermal lens effect (TLE) is extensively explored in laser systems for determining thermal lens focal lengths, its application in quantifying solution concentrations remains underexplored. This research explores the relationship between various liquid concentrations and the interference fringes induced by the TLE. A novel approach is introduced, utilizing TLE to measure solution concentrations, with integration of image processing and discrete Fourier transform (DFT) techniques for feature extraction from interference rings. Further, machine learning, specifically backpropagation artificial neural network (BP-ANN), is employed to model concentration measurement. The model demonstrates high accuracy, evidenced by low root mean square error (RMSE) values of 3.055 and 5.396 for the training and test sets, respectively. This enables precise, real-time determination of soy sauce concentration, offering significant implications for industrial testing, environmental monitoring, and other related fields.

Physical layer security scheme for key concealment and distribution based on carrier scrambling.

The purpose of this study is to present a physical layer security scheme for key concealment and distribution based on carrier scrambling. The three-dimensional (3D) Lorenz system is used to generate independent chaotic sequences that encrypt the information with bit, constellation and subcarrier. In order to realize the flexible distribution of the key and ensure its security, the key information is loaded into a specific subcarrier. While key subcarrier and the ciphertext subcarrier are scrambled simultaneously. The encrypted key position information is processed and transmitted in conjunction with the training sequence (TS) to facilitate demodulation by the legitimate receiver. The processed TS can accommodate up to 10 key position information, thereby demonstrating the scheme's exceptional scalability. Experimental results show that the proposed scheme can safely transmit 131.80 Gb/s Orthogonal frequency division multiplexing (OFDM) signals across 2 km 7-core fiber. Meanwhile, the scheme enables simultaneous flexible distribution and concealment of the key, thereby offering a promising solution for physical layer security.