Mid-infrared all-fiber light-induced thermoelastic spectroscopy sensor based on hollow-core anti-resonant fiber

In this work, we establish a quantitative relationship between the fluorescence signal intensity of acetone and toluene and their concentration, and acetone/toluene planar laser‐induced fluorescence (PLIF) is developed to measure the concentrations of two components simultaneously, providing an equivalent ratio distribution of the flow field. Due to a thorough consideration of the tracer effect on each other's fluorescence signals, the uncertainty in the PLIF concentration measurement is reduced to 10.4%. Experimental results of OH‐PLIF and acetone/toluene PLIF indicate that the equivalence ratio distribution obtained by acetone/toluene PLIF in cold‐state flow fields can be employed to predict and analyze the trend of equivalence ratio distribution in the combustion field.

Quantitative acetone/toluene planar laser‐induced fluorescence measurements of equivalent ratio

Chang,

Yu,

Peng

et al. 2024

A systematic study on linear thermal expansion coefficient of metals based on interferometric measurement with Fresnel bimirror

Lu,

Zhao,

Lin

et al. 2024

Linear thermal expansion coefficient, which is vital for measuring the thermal expansion characteristics of metals, has been attracting considerable attention globally. Herein, a novel design based on Fresnel bimirror has been developed. In this design, when the upper end of the object to be measured comes in contact with a tilted double‐sided mirror, the temperature rises and intersection angle of the Fresnel bimirror decreases. Meanwhile, interference fringe spacing becomes narrower, while the number of fringes increases. An imaging system based on a digital microscope and smartphone is also incorporated in this design, which records the changes in the interference fringes. Then, using a self‐programmed software, the linear thermal expansion coefficients of Cu, Fe, and Al samples are determined at elevated temperatures as 17.85 ± 0.23 × 10−6/°C (), 11.8 ± 0.09 × 10−6/°C (), and 23.34 ±0.16 × 10−6/°C (), respectively, with a relative error of less than 1.6%. A cooling process is also designed, and the average value of the linear thermal expansion coefficient of metal samples during heating and cooling conditions is determined. The measurement results obtained via the finite‐method simulation demonstrate the feasibility and reliability of the system. Overall, this study provides a new idea for measuring the linear thermal expansion coefficient of metals.

Research on performance enhancement scheme of optical camera communication based on adaptive exponential weighted moving average algorithm

Jia,

Tian,

Feng

2024

When the COMS camera of optical camera communication (OCC) system acquired the information image, the grayscale value of pixels fluctuated due to the influence of blooming effect and light noise, so that the data logic could not be correctly judged by the decision threshold, which affected the bit error rate (BER) performance transmission distance and data rate, and degraded the system performance. In this paper, the adaptive exponential weighted moving average algorithm is proposed, and the optimal grayscale value matrix of signal demodulation is verified by experiment, so as to reduce the fluctuation of grayscale value and improve the performance of OCC system. The experimental results show that for data processing and analysis based on ZYNQ7020 experimental platform, a 7% forward error correction（BER = 3.8 × 10−3）requirements can be satisfied at 150 cm when the data rate is 3 Kbps, and a 7% forward error correction（BER = 3.8 × 10−3）requirements can be satisfied at 100 cm when the data rate is 5 Kbps.