Luan Bingqing, Shao Changjin, Liu Feiyu, Yang Zhenqing «Optimization of a H₂ Blending Concentration Sensor in Natural Gas Utilizing a Four-Branch Closed Resonator» Акустический журнал, 71, № 3, с. pp378-391 (2025)

This paper investigates the feasibility of utilizing a closed four-branch resonant as a concentration sensor during the transportation of natural gas mixed with H2. Accurate detection of changes in H₂ concentration is critical to ensuring pipeline operational safety, as an increase in H₂ content can lead to delayed fractures or localized cracks within the pipeline. By carefully tuning the parameters of the four-branch closed resonator sensor, this study significantly improves its performance metrics. Specifically, the figure of merit reaches 4.93·10⁵, the quality factor is 8.96·10⁵, and the concentration detection limit is as low as 1.01·10^–7. In addition, the device’s simple design and superior performance make it particularly suitable for applications in biosensing, air quality monitoring, and the detection of oxygen and harmful gases.

Yicen Li, Rongguang Li, Ling Sun, Chen Sixun Sun, Zhiqiang Cheng «Stress Measurement of Orthogonal Fiber-Reinforced Composites under Biaxial Stress Conditions Based on Critically Refracted Longitudinal Wave Method» Акустический журнал, 71, № 3, с. pp368-377 (2025)

This study derives the relationship between ultrasonic velocity and stress in orthogonal fiber-reinforced composites under biaxial stress conditions. By calibrating the stress coefficients in two directions, the stress values in the composite plate can be obtained using two time-of-flight measurements. The calibration of stress coefficients requires determining the first critical incident angle. Thus, micromechanics methods were used to calculate the stiffness matrix of the composite material, which was then input into a finite element model to simulate the ultrasonic velocity in the orthogonal composite material. This process determined the incident angle capable of exciting the critical refracted longitudinal wave, namely the first critical incident angle. Rectangular specimens of orthogonal composites were manufactured from glass fiber-reinforced composite plates with bidirectional layup, and uniaxial tensile tests were conducted to verify the accuracy of the first critical incident angle and to calibrate the stress coefficients. It was found that the normal stress in the fiber direction results in a decrease in the ultrasonic velocity in both the fiber and perpendicular directions. To verify the accuracy of ultrasonic stress measurement, uniaxial tensile specimens with a central hexagonal area under biaxial stress conditions and standard biaxial tensile specimens were specially designed. The experimental results for both specimens showed that the ultrasonic stress measurement results were in good agreement with the stress measured using strain gauges, confirming the accuracy and practicality of the ultrasonic stress measurement method.