Optimized VMD algorithm for noise reduction of absorption spectra of CO₂

Abstract

The end tidal carbon dioxide (EtCO₂) is crucial for monitoring patients respiratory function, which reflects the status of lung ventilation and gas exchange. Therefore, achieving accurate measurements of EtCO₂ holds significant importance in clinical practice. The measurements of EtCO₂ based on wavelength modulation-direct absorption spectroscopy (WM-DAS) had great advantages and the noise reduction of spectrum was very important. An optimized variational mode decomposition (VMD) algorithm improved by the dung beetle optimization algorithm and wavelet packet denoising algorithm was proposed to enhance the measurement accuracy of EtCO₂ concentration. The dung beetle optimization algorithm was used to obtain the optimal number of decomposition mode layers K and secondary penalty factor α. The optimal parameters were used to decompose the original transmitted light intensity signal with noise, and a series of intrinsic mode functions (IMFs) were obtained. Pearson correlation coefficient (R) was used to select the pure signal and the noisy signal, and the noisy signal was denoised by wavelet packet denoising algorithm. The transmitted light intensity signal was reconstructed by the signal processed by wavelet packet denoising algorithm and the pure signal. The results showed that the proposed algorithm could effectively remove the noise of signal of transmitted light intensity and improve the accuracy of concentration measurements of EtCO₂.

Keywords

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References

[1] Li Y, Wei X, Zhou Yet al.. Research progress of electronic nose technology in exhaled breath disease analysis. Microsystems & nano engineering, 2023, 9(1): 129 J]

[2] Zhou Z, Shen C, Long Wet al.. Simultaneous real-time detection of fractional exhaled nitric oxide and end-tidal carbon dioxide by quantum cascade laser absorption spectroscopy. Spectrochimica acta part A: molecular and biomolecular spectroscopy, 2024, 308: 123750 J]

[3] Peng Z, Du Y, Ding Y. Highly sensitive, calibration-free WM-DAS method for recovering absorbance–Part I: theoretical analysis. Sensors, 2020, 203681 J]

[4] SHI Y, HU Z, NIU M, et al. High-sensitive double incidence multi-pass cell for trace gas detection based on TDLAS[J]. Sensors and actuators B: chemical, 2024: 135829.

[5] Du Y, Peng Z, Ding Y. Wavelength modulation spectroscopy for recovering absolute absorbance. Optics express, 2018, 2679263-9272 J]

[6] Huang N E, Shen Z, Long S Ret al.. The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. Proceedings of the Royal Society of London. Series A: mathematical, physical and engineering sciences, 1998, 454(1971): 903-995 J]

[7] Tian C, Zou L C, Ruan Bet al.. Optimization method of mid-infrared TDLAS detection of low concentration NO based on EMD. Journal of quantum electronics, 2021, 38(05): 661-668[J]

[8] Wang J, Zhang L F, Yang J Set al.. Noise reduction of wavelength modulated signal based on wavelet and empirical mode decomposition. Laser and optoelectronics progress, 2022, 59(18): 481-487[J]

[9] Guo X Q, Qiu X B, Ji W Het al.. Suppression of interference fringes in tunable semiconductor laser absorption spectra based on empirical mode decomposition. Advances in laser and optoelectronics, 2018, 55(11): 463-469[J]

[10] Sheng A Z, Xu Y, Feng X Aet al.. Study on noise reduction of tunable diode laser absorption spectroscopy detection signal based on complete ensemble empirical mode decomposition with adaptive noise-detrended fluctuation analysis-wavelet soft threshold. Journal of nanoelectronics and optoelectronics, 2022, 17(5): 758-768 J]

[11] SHOU L W, WEI H G, ZHAO W W, et al. Interference fringe suppression in tunable diode laser absorption spectroscopy based on CEEMDAN-WTD[J]. Frontiers in physics, 2022.

[12] DRAGOMIRETSKIY K, ZOSSO D. Variational mode decomposition[J]. IEEE transition signal processing, 2014, 62(3).

[13] Zhuang D, Liu H, Zheng Het al.. The IBA-ISMO method for rolling bearing fault diagnosis based on VMD-sample entropy. Sensors, 2023, 23(2): 991 J]

[14] Zhang H, Wang L, Zou C Het al.. Simulation analysis of signal noise reduction method in TDLAS system. Laser journal, 2022, 43073138[J]

[15] Zhang R L, Tu X H. Variational mode decomposition of second harmonics and wavelet threshold function denoising. Acta optica sinica, 2022, 420280-87[J]

[16] Qi G, Zhao Z, Zhang Ret al.. Optimized VMD algorithm for signal noise reduction based on TDLAS. Journal of quantitative spectroscopy and radiative transfer, 2024, 312: 108807 J]

[17] Li J, Peng Z, Ding Y. Measurements of C₂H₄ transitions near 1.625µm and C₂H₄ concentrations using the WM-DAS method. Vibrational spectroscopy, 2019, 103: 102936 J]

[18] Wang Z, Du Y, Ding Yet al.. A wide-range and calibration-free spectrometer which combines wavelength modulation and direct absorption spectroscopy with cavity ring down spectroscopy. Sensors, 2020, 20(3): 585 J]

[19] Jiang Z J, Zhang J, Zhang X. Denoising method of pipeline leakage signal based on VMD and Hilbert transform. Journal of sensors, 2023, 1: 1939606 J]

[20] PAN J, LI S, ZHOU P, et al. Dung beetle optimization algorithm guided by improved sine algorithm[J]. Computer engineering and applications, 2023.

[21] Liu K, Yin G, Zhang Zet al.. High-resolution and high-precision φ-OFDR strain sensing scheme based on adaptive phase unwrap and wavelet packet denoising. Journal of lightwave technology, 2024, 422891-897 J]

[22] Pan Z, Xu D, Zhang Yet al.. New energy transmission line fault location method based on Pearson correlation coefficient. Journal of physics: conference series, 2024, 2717(1): 012007[J]

[23] Qi R, He S, Li Xet al.. Simulation of TDLAS direct absorption signal based on HITRAN spectral database. Spectroscopy and spectral analysis, 2015, 1: 172-177[J]

[24] Fuadi R M, Yulianto E, Irianto B Get al.. Design of carbon dioxide levels measurement in human expiration using EtCO₂ capnography method. Indonesian journal of electronics, electromedical engineering, and medical informatics, 2023, 5(1): 45-51 J]

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