Articles de revues : « Tdlas/wms »

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Xiao, Xiao, Jianquan Zhang, Guopeng Zhou, Fengqi Yu, George N. Lawrence et Zhibin Wang. « Study on the Technique for Wavelength Modulation Spectroscopy with Narrow Band Interference Filter Based External Cavity Diode Laser ». Journal of Physics : Conference Series 2597, n^o 1 (1 septembre 2023) : 012012. http://dx.doi.org/10.1088/1742-6596/2597/1/012012.

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Abstract In this study, an improved tunable external cavity diode laser (ECDL) is proposed. It is on the basis of narrow band interference filter, and its theoretical research is carried out as the light source of tunable diode laser absorption spectrum-wavelength modulation spectrum (TDLAS-WMS) system. The proposed model can use piezoelectric ceramic actuator to change and modulate its output central wavelength so that the laser central wavelength could periodically scan the absorption spectral band of the desired gas. Compared with the tunable monolithic diode laser, the narrow band interference filter based tunable ECDL might be able to accurately sense the type and concentration of a large variety of gases. Therefore, it can be used in the TDLAS-WMS system for high precision gas sensing and is expected to replace the tunable monolithic diode laser.

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Jiang, Chunlei, Yunfei Liu, Bo Yu, Shuxin Yin et Peng Chen. « TDLAS-WMS second harmonic detection based on spectral analysis ». Review of Scientific Instruments 89, n^o 8 (août 2018) : 083106. http://dx.doi.org/10.1063/1.5031683.

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Liang, Tiantian, Shunda Qiao, Xiaonan Liu et Yufei Ma. « Highly Sensitive Hydrogen Sensing Based on Tunable Diode Laser Absorption Spectroscopy with a 2.1 μm Diode Laser ». Chemosensors 10, n^o 8 (11 août 2022) : 321. http://dx.doi.org/10.3390/chemosensors10080321.

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As a new form of energy, hydrogen (H2) has clean and green features, and the detection of H2 has been a hot topic in recent years. However, the lack of suitable laser sources and the weak optical absorption of H2 limit the research concerning its detection. In this study, a continuous-wave distributed feedback (CW-DFB) diode laser was employed for sensing H2. Tunable diode laser absorption spectroscopy (TDLAS) was adopted as the detection technique. The strongest H2 absorption line, located at 4712.90 cm−1 (2121.83 nm, line strength: 3.19 × 10−26 cm−1/cm−2 × molec), was selected. We propose a H2-TDLAS sensor based on the wavelength modulation spectroscopy (WMS) technique and a Herriott multipass gas cell (HMPC) with an optical length of 10.13 m to achieve a sensitive detection. The WMS technique and second harmonic (2f) demodulation technique were utilized to suppress system noise and simplify the data processing. The 2f signal of the H2-TDLAS sensor, with respect to different H2 concentrations, was measured when the laser wavelength modulation depth was at the optimal value of 0.016 cm−1. The system’s signal-to-noise ratio (SNR) and minimum detection limit (MDL) were improved from 248.02 and 0.40% to 509.55 and 0.20%, respectively, by applying Daubechies (DB) wavelet denoising, resulting in 10 vanishing moments. The Allan variance was calculated, and the optimum MDL of 522.02 ppm was obtained when the integration time of the system was 36 s.

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Mu, Ye, Tianli Hu, He Gong, Ruiwen Ni et Shijun Li. « A Trace C2H2 Sensor Based on an Absorption Spectrum Technique Using a Mid-Infrared Interband Cascade Laser ». Micromachines 9, n^o 10 (19 octobre 2018) : 530. http://dx.doi.org/10.3390/mi9100530.

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In this study, tunable diode laser absorption spectroscopy (TDLAS) combined with wavelength modulation spectroscopy (WMS) was used to develop a trace C2H2 sensor based on the principle of gas absorption spectroscopy. The core of this sensor is an interband cascade laser that releases wavelength locks to the best absorption line of C2H2 at 3305 cm−1 (3026 nm) using a driving current and a working temperature control. As the detected result was influenced by 1/f noise caused by the laser or external environmental factors, the TDLAS-WMS technology was used to suppress the 1/f noise effectively, to obtain a better minimum detection limit (MDL) performance. The experimental results using C2H2 gas with five different concentrations show a good linear relationship between the peak value of the second harmonic signal and the gas concentration, with a linearity of 0.9987 and detection accuracy of 0.4%. In total, 1 ppmv of C2H2 gas sample was used for a 2 h observation experiment. The data show that the MDL is low as 1 ppbv at an integration time of 63 s. In addition, the sensor can be realized by changing the wavelength of the laser to detect a variety of gases, which shows the flexibility and practicability of the proposed sensor.

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Lu, Rong Jun, De Ming Shen, Qian Qian Du, Bao Zhen Huang et Jian Shu Shi. « Tuning Characteristics of DFB Diode Laser and its Application to TDLAS Gas Sensor Design ». Applied Mechanics and Materials 511-512 (février 2014) : 173–77. http://dx.doi.org/10.4028/www.scientific.net/amm.511-512.173.

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Static and dynamic tuning characteristics of Distribute Feedback (DFB) diode lasers are investigated with practical laser devices. These characteristics are the basic guidelines for practical TDLAS sensors design. Static tuning characteristics help to select suitable diode lasers from limited available laser devices with specific wavelength and to set an appropriate working current and temperature. Dynamic tuning characteristics decide the sweep speed of current slope in both direct absorb Spectroscopy (DAS) and wavelength modulation Spectroscopy (WMS). Because of nonlinearity in the relation between wavelength and tuning current, the measured spectral line position should be corrected by the dynamic characteristics. For WMS, current tuning efficient and IM/AM (Intense modulation/Amplitude modulation) differential phase could be utilized to optimize laser modulation and harmonic components demodulation.

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Zhu, Xiaorui, Shunchun Yao, Wei Ren, Zhimin Lu et Zhenghui Li. « TDLAS Monitoring of Carbon Dioxide with Temperature Compensation in Power Plant Exhausts ». Applied Sciences 9, n^o 3 (28 janvier 2019) : 442. http://dx.doi.org/10.3390/app9030442.

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Temperature variations of flue gas have an effect on carbon dioxide (CO2) emissions monitoring. This paper demonstrates accurate CO2 concentration measurement using tunable diode laser absorption spectroscopy (TDLAS) with temperature compensation methods. A distributed feedback diode laser at 1579 nm was chosen as the laser source for CO2 measurements. A modeled flue gas was made referring to CO2 concentrations of 10–20% and temperatures of 298–338 K in the exhaust of a power plant. Two temperature compensation methods based on direct absorption (DA) and wavelength modulation (WMS) are presented to improve the accuracy of the concentration measurement. The relative standard deviations of DA and WMS measurements of concentration were reduced from 0.84% and 0.35% to 0.42% and 0.31%, respectively. Our experimental results have validated the rationality of temperature compensations and can be further applied for high-precision measurement of gas concentrations in industrial emission monitoring.

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Xu Jun, 徐俊, 李云飞 Li Yunfei, 程跃 Cheng Yue, 檀剑飞 Tan Jianfei, 刘东 Liu Dong et 周振 Zhou Zhen. « 基于TDLAS-WMS的甲烷泄漏遥测系统研制 ». Laser & ; Optoelectronics Progress 60, n^o 6 (2023) : 0628006. http://dx.doi.org/10.3788/lop213323.

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ZHAO Chenglong, 赵成龙, 黄丹飞 HUANG Danfei, 刘智颖 LIU Zhiying, 王昱琪 WANG Yuqi, 钟艾琦 ZHONG Aiqi, 张耹铭 ZHANG Qinming et 孟凡宏 MENG Fanhong. « 开放型TDLAS-WMS技术CO2痕量气体检测 ». ACTA PHOTONICA SINICA 51, n^o 2 (2022) : 0230001. http://dx.doi.org/10.3788/gzxb20225102.0230001.

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Ban, Deyue, Nan Li, Yongqiu Zheng et Chenyang Xue. « CO2 Measurement under Different Pressure and Vibration Conditions Using Tunable Diode Laser Absorption Spectroscopy ». Photonics 11, n^o 2 (4 février 2024) : 146. http://dx.doi.org/10.3390/photonics11020146.

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The greenhouse effect resulting from fuel combustion has drawn growing attention, and CO2 emissions from fossil fuel power stations are one of the main sources of greenhouse gases. It is crucial to monitor the concentration of CO2 in the flue gas ducts of these stations. However, pressure and vibration caused by the combustion of boilers make the measurement of CO2 in flue gas ducts extremely challenging. In this study, tunable diode laser absorption spectroscopy (TDLAS) combined with Wave Modulation Spectroscopy (WMS) was employed to measure the concentration of CO2 under different pressure and vibration conditions in the laboratory. The absorption line of CO2 at the wavenumber 6357.38 cm−1 was recorded under varying pressure conditions ranging from 0 to 1.4 atm, acceleration conditions ranging from 0 to 7.7 m/s2, and a combination of both. Firstly, a negative linear correlation was found between the pressure and the amplitude of the second harmonic, with a maximum relative error of 4.645% observed at a pressure of 1.4 atm. Secondly, the maximum acceleration that the system can withstand was determined to be 7.3 m/s2, as it was not possible to provide a sufficiently low fitting error at higher accelerations. For the combined effects of the pressure and vibration, a dramatic increase in the relative error of amplitude can be observed within the acceleration range of 5.0~6.0 m/s2 while under the pressure conditions of 0.6 atm, 1.0 atm, and 1.4 atm. Moreover, the maximum endurable acceleration decreases with the increase in pressure, which infers that effective measurements can be achieved when the acceleration is below 5 m/s2 within the pressure range of 0~1.4 atm. This suggests that TDLAS combined with WMS possesses a potential for online measuring of CO2 concentrations in flue gas ducts within a certain acceleration range. This work can provide some insights for stable gas detection using TDLAS under varied pressure and vibration conditions.

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Luo, Qiwu, Chunhua Yang, Cao Song, Jian Zhou et Weihua Gui. « TDLAS/WMS Embedded System for Oxygen Concentration Detection of Glass Vials with Variational Mode Decomposition ». IFAC-PapersOnLine 53, n^o 2 (2020) : 11626–31. http://dx.doi.org/10.1016/j.ifacol.2020.12.644.

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Huang, Ang, Zhang Cao, Wenshuai Zhao, Hongyu Zhang et Lijun Xu. « Frequency-Division Multiplexing and Main Peak Scanning WMS Method for TDLAS Tomography in Flame Monitoring ». IEEE Transactions on Instrumentation and Measurement 69, n^o 11 (novembre 2020) : 9087–96. http://dx.doi.org/10.1109/tim.2020.2998935.

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Luo, Qiwu, Cao Song, Chunhua Yang, Weihua Gui, Yichuang Sun et Zoe Jeffrey. « Headspace Oxygen Concentration Measurement for Pharmaceutical Glass Bottles in Open-Path Optical Environment Using TDLAS/WMS ». IEEE Transactions on Instrumentation and Measurement 69, n^o 8 (août 2020) : 5828–42. http://dx.doi.org/10.1109/tim.2019.2958582.

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Peng, Zhimin, Yanjun Du et Yanjun Ding. « Highly Sensitive, Calibration-Free WM-DAS Method for Recovering Absorbance—Part I : Theoretical Analysis ». Sensors 20, n^o 3 (26 janvier 2020) : 681. http://dx.doi.org/10.3390/s20030681.

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The absorbance is of great importance in the tunable diode laser absorption spectroscopy (TDLAS) as it contains information of both gas properties and spectroscopic parameters. A novel, calibration-free wavelength modulation-direct absorption spectroscopy (WM-DAS) is proposed and experimentally verified in this two-part paper. This method combines the capability of absorbance measurement from DAS and the advantages of enhanced noise rejection and high sensitivity from WMS. In this Part I, we focus on the full theoretical basis and procedures of this method from the following three aspects: the high-accuracy characterizations of laser frequency and intensity, noise rejection ability by extracting the characteristic spectra through the fast Fourier transform (FFT) of the light intensity, and the simultaneous fitting strategy for both baseline and absorbance. The preliminary validation experiment of CO transition at 4300.6999 cm−1 in a static gas cell shows the high accuracy of the proposed method.

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Lan, Lijuan, Homa Ghasemifard, Ye Yuan, Stephan Hachinger, Xinxu Zhao, Shrutilipi Bhattacharjee, Xiao Bi, Yin Bai, Annette Menzel et Jia Chen. « Assessment of Urban CO2 Measurement and Source Attribution in Munich Based on TDLAS-WMS and Trajectory Analysis ». Atmosphere 11, n^o 1 (2 janvier 2020) : 58. http://dx.doi.org/10.3390/atmos11010058.

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Anthropogenic carbon dioxide (CO2) emissions mainly come from cities and their surrounding areas. Thus, continuous measuring of CO2 in urban areas is of great significance to studying human CO2 emissions. We developed a compact, precise, and self-calibrated in-situ CO2/H2O sensor based on TDLAS (tunable diode laser absorption spectroscopy), WMS (wavelength modulation spectroscopy), and VCSEL (vertical-cavity surface-emitting laser). Multi-harmonic detection is utilized to improve the precision of both measurements to 0.02 ppm for CO2 and 1.0 ppm for H2O. Using the developed sensor, we measured CO2 concentrations continuously in the city center of Munich, Germany, from February 2018 to January 2019. Urban CO2 concentrations are strongly affected by several factors, including vegetation photosynthesis and respiration (VPR), planetary boundary layer (PBL) height, and anthropogenic activities. In order to further understand the anthropogenic contribution in terms of CO2 sources, the HySPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model was applied to calculate six-hour backward trajectories. We analyzed the winter CO2 with the trajectory clustering, PSCF (potential source contribution function), and CWT (concentration weighted trajectory) methods, and found that local emissions have a great impact on urban CO2 concentration, with main emission sources in the north and southeast directions of the measurement site. In situations with an uneven trajectory distribution, PSCF proves somewhat superior in predicting the potential emission sources compared to CWT.

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Xin Wenhui, 辛文辉, 任卓勇 Ren Zhuoyong, 樊建鑫 Fan Jianxin, 李仕春 Li Shichun, 乐静 Yue Jing et 华灯鑫 Hua Dengxin. « 基于FPGA的TDLAS-WMS信号控制系统设计及实现 ». Laser & ; Optoelectronics Progress 60, n^o 5 (2023) : 0530001. http://dx.doi.org/10.3788/lop213332.

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Zhao, Wenshuai, Lijun Xu, Ang Huang, Xin Gao, Xizi Luo, Hongyu Zhang, Haitao Chang et Zhang Cao. « A WMS Based TDLAS Tomographic System for Distribution Retrievals of Both Gas Concentration and Temperature in Dynamic Flames ». IEEE Sensors Journal 20, n^o 8 (15 avril 2020) : 4179–88. http://dx.doi.org/10.1109/jsen.2019.2962736.

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Fisher, Edward M. D., et Thomas Benoy. « Interleaving and Error Concealment to Mitigate the Impact of Packet Loss in Resource-Constrained TDLAS/WMS Data Acquisition ». IEEE Transactions on Instrumentation and Measurement 67, n^o 2 (février 2018) : 439–48. http://dx.doi.org/10.1109/tim.2017.2761558.

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Gao, Lu, Ying Zang, Guangwu Zhao, Hengnian Qi, Qizhe Tang, Qingshan Liu et Liangquan Jia. « Research on the Seed Respiration CO2 Detection System Based on TDLAS Technology ». International Journal of Optics 2023 (22 mars 2023) : 1–13. http://dx.doi.org/10.1155/2023/8017726.

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The traditional detection method of CO2 concentration in seed respiration has defects such as low detection accuracy, low detection efficiency, and inability to monitor in real time. In order to solve these problems, we report a seed respiration CO2 detection system based on wavelength modulation spectroscopy (WMS) techniques in tunable diode laser absorption spectroscopy (TDLAS). This system uses a 2004 nm distributed feedback (DFB) laser as the light source, and a double-layer seed respiration device (about 1.5 L) is designed based on Herriott cell with an effective optical path of about 21 meters. Then, the second harmonic (2f) signal is extracted by the wavelength modulation method for CO2 concentration inversion. When the ambient temperature and pressure changes greatly, the corrected 2f signal is used for CO2 concentration inversion to improve the accuracy. A series of verification and comparison experiments have proved that the seed respiration CO2 detection system has the advantages of strong stability, high sampling frequency, and high detection accuracy. Finally, we used the developed system to measure the respiration intensity and respiration rate of 1 g corn seeds. The respiration intensity curves and respiration rate change details show that the seed respiration CO2 detection system is more suitable for a small amount of seeds than nondispersive infrared (NDIR) CO2 sensor and gas chromatography in real-time monitoring of the breathing process.

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Li, Jing, Renjie Li, Yan Liu, Fei Li, Xin Lin, Xilong Yu, Weiwei Shao et Xiang Xu. « In Situ Measurement of NO, NO2, and H2O in Combustion Gases Based on Near/Mid-Infrared Laser Absorption Spectroscopy ». Sensors 22, n^o 15 (31 juillet 2022) : 5729. http://dx.doi.org/10.3390/s22155729.

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In this study, a strategy was developed for in situ, non-intrusive, and quantitative measurement of the oxides of nitrogen (NO and NO2) to describe emission characteristics in gas turbines. The linear calibration-free wavelength modulation spectroscopy (LCF-WMS) approach combined with the temperature profile-fitting strategy was utilized for trace NO and NO2 concentration detection with broad spectral interference from gaseous water (H2O). Transition lines near 1308 nm, 5238 nm, and 6250 nm were selected to investigate the H2O, NO, and NO2 generated from combustion. Experiments were performed under different equivalence ratios in a combustion exhaust tube, which was heated at 450–700 K, with an effective optical length of 1.57 m. Ultra-low NOx emissions were captured by optical measurements under different equivalence ratios. The mole fractions of H2O were in agreement with the theoretical values calculated using Chemkin. Herein, the uncertainty of the TDLAS measurements and the limitation of improving the relative precision are discussed in detail. The proposed strategy proved to be a promising combustion diagnostic technique for the quantitative measurement of low-absorbance trace NO and NO2 with strong H2O interference in real combustion gases.

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Li, Bin, Qi-Xin He, Hui-Fang Liu et Yi-Ding Wang. « Integrated Wavelength-Tunable Light Source for Optical Gas Sensing Systems ». International Journal of Optics 2015 (2015) : 1–6. http://dx.doi.org/10.1155/2015/719234.

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A compact instrument consisting of a distributed feedback laser (DFB) at 1.65 μm was developed as a light source for gas sensing systems using tunable diode laser absorption spectroscopy (TDLAS) technique. The wavelength of laser is tuned by adjusting the laser working temperature and injection current, which are performed by self-developed temperature controller and current modulator respectively. Stability test shows the fluctuation of the laser temperature is within the range of ±0.02°C. For gas detection experiments, the wavelength is tuned around the gas absorption line by adjusting laser temperature and is then shifted periodically to scan across the absorption line by the laser current modulator, which generates a 10 Hz saw wave signal. In addition, the current modulator is able to generate sine wave signal for gas sensing systems using wavelength modulation spectroscopy (WMS) technique involving extraction of harmonic signals. The spectrum test proves good stability that the spectrum was measured 6 times every 10 minutes at the constant temperature and current condition. This standalone instrument can be applied as a light source for detection systems of different gases by integrating lasers at corresponding wavelength.

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Mao, Minxia, Ting Gong, Kangjie Yuan, Lin Li, Guqing Guo, Xiaocong Sun, Yali Tian, Xuanbing Qiu, Christa Fittschen et Chuanliang Li. « A Coin-Sized Oxygen Laser Sensor Based on Tunable Diode Laser Absorption Spectroscopy Combining a Toroidal Absorption Cell ». Sensors 23, n^o 19 (5 octobre 2023) : 8249. http://dx.doi.org/10.3390/s23198249.

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Laser gas sensors with small volume and light weight are in high demand in the aerospace industry. To address this, a coin-sized oxygen (O2) sensor has been successfully developed based on a small toroidal absorption cell design. The absorption cell integrates a vertical-cavity surface-emitting laser (VCSEL) and photodetector into a compact unit, measuring 90 × 40 × 20 mm and weighing 75.16 g. Tunable diode laser absorption spectroscopy (TDLAS) is used to obtain the O2 spectral line at 763 nm. For further improving the sensitivity and robustness of the sensor, wavelength modulation spectroscopy (WMS) is utilized for the measurement. The obtained linear correlation coefficient is 0.9994. Based on Allen variance analysis, the sensor achieves an impressive minimum detection limit of 0.06% for oxygen concentration at an integration time of 318 s. The pressure-dependent relationship has been validated by accounting for the pressure factor in data processing. To affirm its efficacy, the laser spectrometer underwent continuous atmospheric O2 measurement for 24 h, showcasing its stability and robustness. This development introduces a continuous online laser spectral sensor with potential applications in manned spaceflight scenarios.

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Geng, Yuhan, Tie Zhang, Shengnan Wu et Sailing He. « In Situ All-Fiber Remote Gas Sensing Strategy Based on Anti-Resonant Hollow-Core Fiber and Middle-Hole Eccentric-Core Fiber ». Photonics 11, n^o 4 (26 mars 2024) : 301. http://dx.doi.org/10.3390/photonics11040301.

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Laser absorption spectroscopy for gas sensing basically employs an air pump located at the gas cell probe to draw in ambient gases, and the on-site gas sample is subsequently delivered for laboratory non-real-time analysis. In this study, an in situ all-fiber remote gas sensing strategy is proposed. The anti-resonant hollow-core fiber (AR-HCF) is used as the sensing fiber, and a 20 m middle-hole eccentric-core fiber (MH-ECF) is used as the conducting fiber. The remote ambient gases can be inhaled into the AR-HCF as a result of the negative pressure transmitted through the MH-ECF when pumping gas at the interface of the MH-ECF. Since the real-time monitoring of greenhouse gas emissions in industrial processes holds immense significance in addressing global climate change, the detection of CO2 is achieved with the TDLAS-WMS method, and the gas sensing performance of an all-fiber remote gas sensing structure (RGS) is experimentally validated. The response time t90 under the pumping condition is about 456 s, which is about 30 times faster than that of free diffusion. Allan deviation results for more than one hour of continuous monitoring indicate that the lowest detection limit for the all-fiber RGS is 0.0373% when the integration time is 184 s. The all-fiber remote gas sensing strategy also possesses the benefits of being applicable to multiplex, hazardous gas environment passive monitoring.

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Chang, Jvqiang, Qixin He, Jiakun Li et Qibo Feng. « Oxygen detection system based on TDLAS–WMS and a compact multipass gas cell ». Microwave and Optical Technology Letters, 11 mars 2022. http://dx.doi.org/10.1002/mop.33203.

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Zhou, Yihui, Yunhao Ren, Feng Gao, Zhijun Liu et Dapeng Hu. « Refrigeration experiments of gas wave rotor based on calibration-free WMS-TDLAS method ». Experimental Thermal and Fluid Science, avril 2024, 111206. http://dx.doi.org/10.1016/j.expthermflusci.2024.111206.

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Wang, W. F., B. Yang, H. F. Liu, L. F. Ren, D. He, X. C. Zhao et J. Li. « A multiline fitting method for measuring ethylene concentration based on WMS-2f/1f ». Scientific Reports 13, n^o 1 (15 septembre 2023). http://dx.doi.org/10.1038/s41598-023-42398-2.

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AbstractCoal spontaneous combustion risk assessment is a global technical challenge for the sustainable development of deep mining technology, and C2H4 is a key indicator for early warning of coal spontaneous combustion. Tunable diode laser absorption spectroscopy (TDLAS) has the advantages of high selectivity, high sensitivity, high accuracy and real-time on-line measurement, and it can detect multiple gases simultaneously, so it has significant advantages in the accurate detection of coal spontaneous combustion indicator gases. To address the problem of cross-interference between the near-infrared absorption lines of CH4 and C2H4, which are the indicator gases of spontaneous combustion in coal, a multi-line fitting method was proposed in this study to calibrate the concentration of C2H4. The high-precision Environics2000 automatic standard gas dispenser from the United States, which has a built-in CPU computer control and data control and processing system, was used. Its gas concentration accuracy: ± 1.0%, gas flow accuracy: ± 1.0%, gas repeatability accuracy: ± 1.0%, flow linearity accuracy: ± 0.5%, and inlet operating pressure: minimum 10 psig (0.67 bar) ~ 75 psig (5.04 bar). The measured and simulated WMS-2f/1f signals were multilinearly fitted using a multilinear fitting algorithm and wavelength modulation spectroscopy (WMS), and the measurement of C2H4 concentration was achieved based on the extracted spectral line information. The results show that the maximum relative error of C2H4 concentration measurement is 2.40%, which is 54% lower than that of the conventional 2f peak measurement method, thus demonstrating the effectiveness of the multilinear fitting algorithm in the inversion of C2H4 concentration under the interference of absorption lines. In addition, this study has far-reaching implications for the application of TDLAS technology in the accurate detection of coal spontaneous combustion indicator gases.

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Guo, Songjie, Yan Yang, Guodong Shao, Zhenghui Li, Wei Ren, Juehui Mo, Zhimin Lu et Shunchun Yao. « Correcting the light extinction effect of fly ash particles on the measurement of NO by TDLAS ». Frontiers in Physics 10 (3 octobre 2022). http://dx.doi.org/10.3389/fphy.2022.1020376.

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The measurement of nitric oxide (NO) concentration in power plant flue gas by tunable diode laser absorption spectroscopy (TDLAS) is susceptible to fly ash particles. The presence of fly ash particles causes laser intensity fluctuations and leads to the second harmonic (2f) signal amplitude changes. In this manuscript, we analyzed the influence of particles on the 2f signal and corrected the measurement error of NO concentration by the wavelength modulation-second harmonic (WMS-2f) technique. Specifically, the 2f signal error caused by quartz sand and fly ash particles were measured, and the exponential function representing the peak-to-peak error of the 2f signal was obtained by fitting. Finally, the peak-to-peak value of the 2f signal and the NO concentration were corrected according to the exponential function. After correction, the NO concentration error under the fly ash influence (the particle size in the range of 10–200 μm and the mass concentration is less than 18.26 g/m3) was no more than 2%. This correction method effectively improves the measurement accuracy of NO concentration by the WMS-2f technique in the fly ash environment.

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Wang, Bin, Xiaojun Tang, Yuanying Gan, Xiaoshan Li et Youshui Lu. « TC/WMS-TDLAS mid-infrared detection method for ultra-low concentration carbon isotope methane ». Journal of Analytical Atomic Spectrometry, 2022. http://dx.doi.org/10.1039/d2ja00142j.

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There is a great demand for online high-precision monitoring of carbon isotope methane in the fields of atmospheric monitoring, geological exploration, and oil, natural gas extraction, etc. However, the current...

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He, Qixin, Peipei Dang, Zhiwei Liu, Chuantao Zheng et Yiding Wang. « TDLAS–WMS based near-infrared methane sensor system using hollow-core photonic crystal fiber as gas-chamber ». Optical and Quantum Electronics 49, n^o 3 (21 février 2017). http://dx.doi.org/10.1007/s11082-017-0946-2.

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Liu, Zihuai, Yonggang Li, Qiwu Luo, Chunhua Yang et Weihua Gui. « Harmonic Double Valley Inclination : A Laser Wavelength Self-Diagnosis Identifier for a TDLAS/WMS System on a Filling Production Line ». IEEE Transactions on Industrial Electronics, 2024, 1–12. http://dx.doi.org/10.1109/tie.2024.3395801.

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Eder, Alexander J., Bayu Dharmaputra, Marcel Désor, Camilo F. Silva, Alex M. Garcia, Bruno Schuermans, Nicolas Noiray et Wolfgang Polifke. « Generation Of Entropy Waves By Fully Premixed Flames In A Non-Adiabatic Combustor With Hydrogen Enrichment ». Journal of Engineering for Gas Turbines and Power, 30 août 2023, 1–32. http://dx.doi.org/10.1115/1.4063283.

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Abstract Thermoacoustic combustion instability is a significant concern in gas turbines with hydrogen-enriched fuels. Unsteady combustion generates acoustic waves and fluctuations in burnt gas temperature, known as entropy waves. The latter are convected by the mean flow through the combustor and can cause indirect combustion noise when accelerated. This work demonstrates that entropy waves occur in a fully premixed burner due to unsteady heat transfer at the combustion chamber wall. This mechanism of entropy generation is often neglected in the literature. This work indicates an additional mechanism in CH4-H2-air flames, which may produce entropy waves even in the fully premixed case - differential diffusion of hydrogen results in local fluctuations in equivalence and carbon-to-hydrogen ratios. The adiabatic flame temperature is defined based on these quantities to examine the effect of differential diffusion on the generation of entropy fluctuations. System identification (SI) is applied to time series data obtained from a broadband-forced large eddy simulation (LES) to investigate the generation of entropy waves. The entropy transfer function (ETF) and flame transfer function (FTF) identified are compared to experimental data obtained with TDLAS-WMS for measuring temperature fluctuations and the multi-microphone method. After validating the computational setup, the entropy frequency response is identified at several positions within the combustion chamber, and the effects of generation and convective dispersion of entropy waves are qualitatively investigated. We show that a fully premixed turbulent system may exhibit significant entropy waves caused by wall heat losses and differential diffusion of hydrogen.

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