A pressure measurement and compensation technique was studied by employing a 3.291 μm Continuous Wave (CW) Interband Cascade Laser (ICL) and a dense-patterned Multipass Gas Cell (MPGC) with an effective optical path ...A pressure measurement and compensation technique was studied by employing a 3.291 μm Continuous Wave (CW) Interband Cascade Laser (ICL) and a dense-patterned Multipass Gas Cell (MPGC) with an effective optical path length of 54.6 m. The pressure inside the MPGC was measured based on direct Lorentzian absorption line fitting on the measured absorption spectral signal of CH4, and then pressure compensation was made on the masured CH4 concentration. Pressure calibration was performed from 1.33 ×10^(4) Pa to 10.64 ×10^(4) Pa using a 2.1×10^(6)CH4 sample. An Allan deviation analysis of the measured pressure of a 2.1×10^0 6 CH4 at 9.31×10^(4) Pa pressure indicates a measurement precision of -219.5 Pa with a 2. 2 s averaging time. Fiveteen groups of pressure/concentration measurements of 1.0 ×10^(-6), 1.2×10^(-6), 1.4×10^(-6), 1.6×10^(-6)and 2.1×10^(-6)CH4 samples at different pressures of 1.33×10^(4), 3.99×10^(4) and 6.65 ×10^(4) Pa were performed, and the results proved the feasibility of the proposed pressure measurement and compensation technique.展开更多
In this Letter,we studied a kilohertz nanosecond 1645 nm optical parametric oscillator(OPO)for methane detection.The OPO pump source was an electro-optical Q-switched 1064 nm oscillator,followed by a preamplifier and ...In this Letter,we studied a kilohertz nanosecond 1645 nm optical parametric oscillator(OPO)for methane detection.The OPO pump source was an electro-optical Q-switched 1064 nm oscillator,followed by a preamplifier and two Innoslab amplifiers.Two KTiOAsO4crystals with typeⅡangular phase matching were used as the nonlinear working materials,and two plane mirrors were used for the OPO cavity.We achieved the signal light with an average power of 9.32 W and a minimum pulse duration of 1.8 ns at a repetition rate of 8 kHz for a 54.1 W pump power,and the optical-optical conversion efficiency was 17.3%.The beam quality was measured as M_(x)^(2)=1.08 and M_(y)^(2)=1.22.The wavelength of the signal light was continuously tunable from 1641.9207 to 1648.1791 nm.To the best of our knowledge,this is the highest average power achieved at the kilohertz regime of a 1645 nm laser.展开更多
Because methane is flammable and explosive,the detection process is time-consuming and dangerous,and it is difficult to obtain labeled data.In order to reduce the dependence on marker data when detecting methane conce...Because methane is flammable and explosive,the detection process is time-consuming and dangerous,and it is difficult to obtain labeled data.In order to reduce the dependence on marker data when detecting methane concentration using tunable diode laser absorption spectroscopy(TDLAS)technology,this paper designs a methane gas acquisition platform based on TDLAS and proposes a methane gas concentration detection model based on semi-supervised learning.Firstly,the methane gas is feature extracted,and then semi-supervised learning is introduced to select the optimal feature combination;subsequently,the traditional whale optimization algorithm is improved to optimize the parameters of the random forest to detect the methane gas concentration.The results show that the model is not only able to select the optimal feature combination under limited labeled data,but also has an accuracy of 94.25%,which is better than the traditional model,and is robust in terms of parameter optimization.展开更多
The infrared absorption method for methane concentration detection is an ideal way to detect methane at present. However, it is difficult to spread this method due to its high cost. In this paper, by using a wideband ...The infrared absorption method for methane concentration detection is an ideal way to detect methane at present. However, it is difficult to spread this method due to its high cost. In this paper, by using a wideband infrared light emitting di- ode （LED） accompanied with a PIN photo electric diode, a low-cost methane detection system was designed. To overcome the shortcomings caused by the wide working band, a differential light path was designed. By means of a differential ratio algo- rithm, the stability and the accuracy of the system were guaranteed. Finally, the validity of the system with the proposed algo- rithm was verified by the experiment results.展开更多
High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration inf...High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration information is susceptible to noise, which leads to its useful signal being drowned by noise. A fusion algorithm of variational modal decomposition(VMD) and improved wavelet threshold filtering is proposed, which is used in combination with tunable diode laser absorption spectroscopy(TDLAS) to implement a non-contact, high-resolution methane gas concentration detection. The fusion algorithm can perform noise reduction and further segmentation of the methane gas detection signal. And the simulation and experiment verify the effectiveness of the fusion algorithm, and the experimental results show that for the detection of air containing 10 ppm, 30 ppm, 60 ppm, 80 ppm, and 99 ppm methane, the errors are 12.75%, 8.18%, 3.37%, 2.46%, and 1.78%, respectively.展开更多
<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane is released from waste disposal areas as a result from anaerobic decay of food. Methane causes...<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane is released from waste disposal areas as a result from anaerobic decay of food. Methane causes more greenhouse effects than carbon dioxide so a methane monitoring system is required to warn its release from gas emitting environments. The low explosive limit of methane is 5% in ambient air, so gas leakage is dangerous and can produce explosions. An entire head monitoring system was built around a MQ-4 methane gas sensor as it is cheap and reliable. The design proves to be flexible enough as it can measure CH</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> emissions in ducts, CH</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> in landfills at different depths and even in cattle barns. The measuring system head consists of a suction pump, solenoids, and a methane sensor. Measurements are taken 13 seconds after methane gas sucking. </span><span style="font-family:Verdana;">A timing of 100 seconds is required for purging the chamber before the</span><span style="font-family:Verdana;"> second solenoid is turned-on. Devices temperature during operation was sampled with a thermal Flir-One camera and solenoid coil temperature was of 24.9</span></span><span style="font-family:;" "=""><span style="font-family:Verdana;"><span style="white-space:nowrap;">˚</span>C </span><span style="font-family:Verdana;">after a continuous operation of 30 seconds. As hoses for emission sampling</span><span style="font-family:Verdana;"> become larger time for sampling increases as well as energy consumption.</span></span>展开更多
Outbursts of methane and rocks are, similarly to rock bursts, the biggest hazards in deep mines and are equally difficult to predict. The violent process of the outburst itself, along with the scale and range of hazar...Outbursts of methane and rocks are, similarly to rock bursts, the biggest hazards in deep mines and are equally difficult to predict. The violent process of the outburst itself, along with the scale and range of hazards following the rapid discharge of gas and rocks, requires solutions which would enable quick and unambiguous detection of the hazard, immediate power supply cut-off and evacuation of personnel from potentially hazardous areas. For this purpose, an integrated outburst detector was developed. Assumed functions of the sensor which was equipped with three measuring and detection elements： a chamber for constant measurement of methane concentration, pressure sensor and microphone. Tests of the sensor model were carried out to estimate the parameters which characterize the dynamic properties of the sensor. Given the impossibility of carrying out the full scale experimental outburst, the sensor was tested during the methane and coal dust explosions in the testing gallery at KD Barbara. The obtained results proved that the applied solutions have been appropriate.展开更多
We report a 1.65μm square-Fabry–Pérot[FP]coupled cavity semiconductor laser for methane gas detection.The laser output optical power can reach 7.4 m W with the side mode suppression ratio about 40 d B.The wavel...We report a 1.65μm square-Fabry–Pérot[FP]coupled cavity semiconductor laser for methane gas detection.The laser output optical power can reach 7.4 m W with the side mode suppression ratio about 40 d B.The wavelength tuning range is 2 nm by adjusting the FP cavity injection current,covering the methane absorption line at 1653.72 nm.The lasing wavelength can also be tuned by adjusting the square microcavity injection current or temperature,respectively.Methane gas detection is successfully demonstrated utilizing this laser.展开更多
This work investigated the potential of metal oxide semiconductor(MOS)gas sensors for environmental monitoring of methane.Calibrations were performed under controlled conditions in the lab,and under semi-controlled co...This work investigated the potential of metal oxide semiconductor(MOS)gas sensors for environmental monitoring of methane.Calibrations were performed under controlled conditions in the lab,and under semi-controlled conditions in the field,using a modified head space chamber set-up.Concentrations up to±300 ppm methane were tested.The relationship between sensor conductance and methane concentrations could be very well described using principles from adsorption theory.The adjustable parameters were background conductance G_(0),a sensitivity constant S and a non-ideality coefficient n,where n has a non-rational value between 0 and 1.Sensor behaviour was very different in dry air than in humid air,with the background conductance increasing approximately tenfold and sensitivity decreasing between 20 fold and 80 fold,while the non-ideality coefficient increased from±0.4 to±0.6.Nevertheless,at high methane concentrations comparable conductance values were recorded in dry and humid air.The standard deviation of predicted values was 1.6μS.for the least well described dataset.Using the corresponding calibration curve,a detection limit of 11 ppm is calculated for humid ambient air.This values suggests that MOS sensor are adequately sensitive to be used for methane detection in an agricultural context.展开更多
基金The National Key R&D Program of China(Nos.2016YFD0700101,2016YFC0303902,2017YFB0402800)National Natural Science Foundation of China(Nos.61775079,61627823,61307124)+1 种基金Science and Technology Department of Jilin Province of China(Nos.20140307014SF20140307014SF,2017C027)Changchun Municipal Science and Technology Bureau(No.14KG022)
文摘A pressure measurement and compensation technique was studied by employing a 3.291 μm Continuous Wave (CW) Interband Cascade Laser (ICL) and a dense-patterned Multipass Gas Cell (MPGC) with an effective optical path length of 54.6 m. The pressure inside the MPGC was measured based on direct Lorentzian absorption line fitting on the measured absorption spectral signal of CH4, and then pressure compensation was made on the masured CH4 concentration. Pressure calibration was performed from 1.33 ×10^(4) Pa to 10.64 ×10^(4) Pa using a 2.1×10^(6)CH4 sample. An Allan deviation analysis of the measured pressure of a 2.1×10^0 6 CH4 at 9.31×10^(4) Pa pressure indicates a measurement precision of -219.5 Pa with a 2. 2 s averaging time. Fiveteen groups of pressure/concentration measurements of 1.0 ×10^(-6), 1.2×10^(-6), 1.4×10^(-6), 1.6×10^(-6)and 2.1×10^(-6)CH4 samples at different pressures of 1.33×10^(4), 3.99×10^(4) and 6.65 ×10^(4) Pa were performed, and the results proved the feasibility of the proposed pressure measurement and compensation technique.
文摘In this Letter,we studied a kilohertz nanosecond 1645 nm optical parametric oscillator(OPO)for methane detection.The OPO pump source was an electro-optical Q-switched 1064 nm oscillator,followed by a preamplifier and two Innoslab amplifiers.Two KTiOAsO4crystals with typeⅡangular phase matching were used as the nonlinear working materials,and two plane mirrors were used for the OPO cavity.We achieved the signal light with an average power of 9.32 W and a minimum pulse duration of 1.8 ns at a repetition rate of 8 kHz for a 54.1 W pump power,and the optical-optical conversion efficiency was 17.3%.The beam quality was measured as M_(x)^(2)=1.08 and M_(y)^(2)=1.22.The wavelength of the signal light was continuously tunable from 1641.9207 to 1648.1791 nm.To the best of our knowledge,this is the highest average power achieved at the kilohertz regime of a 1645 nm laser.
基金supported by the Ministry of Education Chunhui Program of China(No.HZKY20220304).
文摘Because methane is flammable and explosive,the detection process is time-consuming and dangerous,and it is difficult to obtain labeled data.In order to reduce the dependence on marker data when detecting methane concentration using tunable diode laser absorption spectroscopy(TDLAS)technology,this paper designs a methane gas acquisition platform based on TDLAS and proposes a methane gas concentration detection model based on semi-supervised learning.Firstly,the methane gas is feature extracted,and then semi-supervised learning is introduced to select the optimal feature combination;subsequently,the traditional whale optimization algorithm is improved to optimize the parameters of the random forest to detect the methane gas concentration.The results show that the model is not only able to select the optimal feature combination under limited labeled data,but also has an accuracy of 94.25%,which is better than the traditional model,and is robust in terms of parameter optimization.
文摘The infrared absorption method for methane concentration detection is an ideal way to detect methane at present. However, it is difficult to spread this method due to its high cost. In this paper, by using a wideband infrared light emitting di- ode （LED） accompanied with a PIN photo electric diode, a low-cost methane detection system was designed. To overcome the shortcomings caused by the wide working band, a differential light path was designed. By means of a differential ratio algo- rithm, the stability and the accuracy of the system were guaranteed. Finally, the validity of the system with the proposed algo- rithm was verified by the experiment results.
基金supported by the Project Grant from Heilongjiang Bayi Agricultural Reclamation University,Heilongjiang,China (No.XDB201813)。
文摘High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration information is susceptible to noise, which leads to its useful signal being drowned by noise. A fusion algorithm of variational modal decomposition(VMD) and improved wavelet threshold filtering is proposed, which is used in combination with tunable diode laser absorption spectroscopy(TDLAS) to implement a non-contact, high-resolution methane gas concentration detection. The fusion algorithm can perform noise reduction and further segmentation of the methane gas detection signal. And the simulation and experiment verify the effectiveness of the fusion algorithm, and the experimental results show that for the detection of air containing 10 ppm, 30 ppm, 60 ppm, 80 ppm, and 99 ppm methane, the errors are 12.75%, 8.18%, 3.37%, 2.46%, and 1.78%, respectively.
文摘<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane is released from waste disposal areas as a result from anaerobic decay of food. Methane causes more greenhouse effects than carbon dioxide so a methane monitoring system is required to warn its release from gas emitting environments. The low explosive limit of methane is 5% in ambient air, so gas leakage is dangerous and can produce explosions. An entire head monitoring system was built around a MQ-4 methane gas sensor as it is cheap and reliable. The design proves to be flexible enough as it can measure CH</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> emissions in ducts, CH</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> in landfills at different depths and even in cattle barns. The measuring system head consists of a suction pump, solenoids, and a methane sensor. Measurements are taken 13 seconds after methane gas sucking. </span><span style="font-family:Verdana;">A timing of 100 seconds is required for purging the chamber before the</span><span style="font-family:Verdana;"> second solenoid is turned-on. Devices temperature during operation was sampled with a thermal Flir-One camera and solenoid coil temperature was of 24.9</span></span><span style="font-family:;" "=""><span style="font-family:Verdana;"><span style="white-space:nowrap;">˚</span>C </span><span style="font-family:Verdana;">after a continuous operation of 30 seconds. As hoses for emission sampling</span><span style="font-family:Verdana;"> become larger time for sampling increases as well as energy consumption.</span></span>
文摘Outbursts of methane and rocks are, similarly to rock bursts, the biggest hazards in deep mines and are equally difficult to predict. The violent process of the outburst itself, along with the scale and range of hazards following the rapid discharge of gas and rocks, requires solutions which would enable quick and unambiguous detection of the hazard, immediate power supply cut-off and evacuation of personnel from potentially hazardous areas. For this purpose, an integrated outburst detector was developed. Assumed functions of the sensor which was equipped with three measuring and detection elements： a chamber for constant measurement of methane concentration, pressure sensor and microphone. Tests of the sensor model were carried out to estimate the parameters which characterize the dynamic properties of the sensor. Given the impossibility of carrying out the full scale experimental outburst, the sensor was tested during the methane and coal dust explosions in the testing gallery at KD Barbara. The obtained results proved that the applied solutions have been appropriate.
基金supported by the National Key R&D Program of China(No.2017YFB0405301)。
文摘We report a 1.65μm square-Fabry–Pérot[FP]coupled cavity semiconductor laser for methane gas detection.The laser output optical power can reach 7.4 m W with the side mode suppression ratio about 40 d B.The wavelength tuning range is 2 nm by adjusting the FP cavity injection current,covering the methane absorption line at 1653.72 nm.The lasing wavelength can also be tuned by adjusting the square microcavity injection current or temperature,respectively.Methane gas detection is successfully demonstrated utilizing this laser.
基金supported by the European Union’s Horizon 2020 research and innovation programme[grant agreement No.825325].
文摘This work investigated the potential of metal oxide semiconductor(MOS)gas sensors for environmental monitoring of methane.Calibrations were performed under controlled conditions in the lab,and under semi-controlled conditions in the field,using a modified head space chamber set-up.Concentrations up to±300 ppm methane were tested.The relationship between sensor conductance and methane concentrations could be very well described using principles from adsorption theory.The adjustable parameters were background conductance G_(0),a sensitivity constant S and a non-ideality coefficient n,where n has a non-rational value between 0 and 1.Sensor behaviour was very different in dry air than in humid air,with the background conductance increasing approximately tenfold and sensitivity decreasing between 20 fold and 80 fold,while the non-ideality coefficient increased from±0.4 to±0.6.Nevertheless,at high methane concentrations comparable conductance values were recorded in dry and humid air.The standard deviation of predicted values was 1.6μS.for the least well described dataset.Using the corresponding calibration curve,a detection limit of 11 ppm is calculated for humid ambient air.This values suggests that MOS sensor are adequately sensitive to be used for methane detection in an agricultural context.
