A data acquisition system for testing gas sensor array response to multi-gas is presented.The testing system is based on the character of the gas response of metal oxide semiconductor gas sensor array.The data acquisi...A data acquisition system for testing gas sensor array response to multi-gas is presented.The testing system is based on the character of the gas response of metal oxide semiconductor gas sensor array.The data acquisition is realized automatically through the real time controlling of the data acquisition card PCI1711.This system is highly attractive for electronic nose,which is a powerful tool for the discrimination of gases.展开更多
As a highly energy-efficient and sensitive radiation source,narrowband thermal emitters provide an ideal solution for non-contact gas detection,enabling the widespread application of mid-infrared“molecular fingerprin...As a highly energy-efficient and sensitive radiation source,narrowband thermal emitters provide an ideal solution for non-contact gas detection,enabling the widespread application of mid-infrared“molecular fingerprint”technology.However,most narrowband thermal emitters lack reconfigurability,limiting their adaptability in practical applications.In this study,we propose a novel dual-band switchable narrowband thermal emitter in the mid-infrared region.The emitter consists of an aperiodic Ge/SiO_(2)/Ge/SiO_(2)(GSGS)structure and a phase change material In_(3)SbTe_(2)(IST).When IST is in the crystalline state,the emitter achieves narrowband emission peaks at wavelengths of 3.79μm and 6.12μm,corresponding to the“on”state.However,when IST transitions to the amorphous state,the dual-band high emission disappears and it features angle-and polarization-independent behavior,representing the“off”state.Furthermore,we verify the physical mechanism behind the high emission through phase and amplitude calculations as well as electric field distribution analysis.Notably,the introduction of the IST provides an additional degree of freedom for tunability.Furthermore,by adjusting the thickness of the spacer layer,the emitter can be precisely tuned to match the characteristic absorption peaks of various mid-infrared gases,such as CH_(4),CO_(2),CO,and NO,enabling multi-gas detection in mixed gas environments.The proposed thermal emitter serves as an effective and low-cost alternative for dual-band narrowband mid-infrared light sources,contributing to the advancement of multi-gas detection strategies.展开更多
The identification of indoor harmful gases is imperative due to their significant threats to human health and safety.To achieve accurate identification,an effective strategy of constructing a sensor array combined wit...The identification of indoor harmful gases is imperative due to their significant threats to human health and safety.To achieve accurate identification,an effective strategy of constructing a sensor array combined with the pattern recognition algorithm is employed.Carbon-based thin-film transistors are selected as the sensor array unit,with semiconductor carbon nanotubes(CNTs)within the TFT channels modified with different metals(Au,Cu and Ti)for selective responses to NH_(3),H_(2)S and HCHO,respectively.For accurate gas species identification,an identification mode that combines linear discriminant analysis algorithms and logistic regression classifier is developed.The test results demonstrate that by preprocessing the sensor array’s sensing data with the LDA algorithm and subsequently employing the LR classifier for identification,a 100%recognition rate can be achieved for three target gases(NH3,H2S and HCHO).This work provides significant guidance for future applications of chip-level gas sensors in the realms of the Internet of Things and Artificial Intelligence.展开更多
A room-temperature broadly tunable mid-infrared difference frequency laser source for highly sensitive trace gas detection has been developed recently in our laboratory. The mid-infrared laser system is based on quasi...A room-temperature broadly tunable mid-infrared difference frequency laser source for highly sensitive trace gas detection has been developed recently in our laboratory. The mid-infrared laser system is based on quasi-phase-matched （QPM） difference frequency generation （DFG） in a multigrating, temperature-controlled periodically poled LiNbO3 （PPLN） crystal and employs two near-infrared diode lasers as pump sources. The mid-infrared coherent radiation generated is tunable from 3.2 μm to 3.7μm with an output power of about 100 μW. By changing one of the pump laser head with another wavelength range, we can readily obtain other needed mid-infrared wavelength range cover. The performance of the mid-infrared laser system and its application to highly sensitive spectroscopic detection of CH4, HCl, CH2O, and NO2 has been carried out. A multi-reflection White cell was used in the experiment gaining ppb-level sensitivity. The DFG laser system has the features of compact, room-temperature operation, narrow line-width, and broadly continuous tunable range for potential applications in industry and environmental monitoring.展开更多
To investigate the non-uniform distribution of different gases passing through the parallel cyclones,experiments were conducted on a circulating fluidized bed(CFB)equipped with six asymmetrical cyclones.A multi-tracer...To investigate the non-uniform distribution of different gases passing through the parallel cyclones,experiments were conducted on a circulating fluidized bed(CFB)equipped with six asymmetrical cyclones.A multi-tracer gas method was used,with CO,O_(2),and CO_(2) chosen to represent gases with different properties in the flue gas at the inlets of the cyclones.The uniformity of multi-gas distribution was evaluated by measuring the concentration deviations of each tracer gas passing through individual cyclones.The results indicate that the concentrations of multi-tracer gases are higher in the middle cyclone among the three,which are located on the tracer gas injection side during the test of single-side secondary air(SA)tracing.The maximum concentration deviation of tracer gases is for CO_(2),while the minimum is for CO.At the three cyclone inlets on the opposite side,the tracer gas with higher density exhibits a more uniform distribution,and the gas uniformity decreases as the density decreases.The effects of superficial velocity,SA ratio,bed inventory,and tracer gas injection region on the uniformity of gas distribution were studied.The results show that superficial velocity and SA ratio primarily affect the uniformity of higher density gases,while bed inventory has a greater influence on lower density gases.The gas distributions are most non-uniform,especially for CO_(2),when the tracer gas injection region is near the rear wall closer to the induced draft fan during the test of regional SA tracing.展开更多
文摘A data acquisition system for testing gas sensor array response to multi-gas is presented.The testing system is based on the character of the gas response of metal oxide semiconductor gas sensor array.The data acquisition is realized automatically through the real time controlling of the data acquisition card PCI1711.This system is highly attractive for electronic nose,which is a powerful tool for the discrimination of gases.
基金supported by the National Natural Science Foundation of China(Grant No.52106099)the Natural Science Foundation of Shandong Province(Grant No.ZR2022YQ57)the Taishan Scholars Program。
文摘As a highly energy-efficient and sensitive radiation source,narrowband thermal emitters provide an ideal solution for non-contact gas detection,enabling the widespread application of mid-infrared“molecular fingerprint”technology.However,most narrowband thermal emitters lack reconfigurability,limiting their adaptability in practical applications.In this study,we propose a novel dual-band switchable narrowband thermal emitter in the mid-infrared region.The emitter consists of an aperiodic Ge/SiO_(2)/Ge/SiO_(2)(GSGS)structure and a phase change material In_(3)SbTe_(2)(IST).When IST is in the crystalline state,the emitter achieves narrowband emission peaks at wavelengths of 3.79μm and 6.12μm,corresponding to the“on”state.However,when IST transitions to the amorphous state,the dual-band high emission disappears and it features angle-and polarization-independent behavior,representing the“off”state.Furthermore,we verify the physical mechanism behind the high emission through phase and amplitude calculations as well as electric field distribution analysis.Notably,the introduction of the IST provides an additional degree of freedom for tunability.Furthermore,by adjusting the thickness of the spacer layer,the emitter can be precisely tuned to match the characteristic absorption peaks of various mid-infrared gases,such as CH_(4),CO_(2),CO,and NO,enabling multi-gas detection in mixed gas environments.The proposed thermal emitter serves as an effective and low-cost alternative for dual-band narrowband mid-infrared light sources,contributing to the advancement of multi-gas detection strategies.
基金financially supported by the National Natural Science Foundation of China(Nos.62071410 and62101477)Hunan Provincial Natural Science Foundation of China(Nos.2021JJ40542 and 2023JJ30596)the science and technology innovation Program of Hunan Province(No.2023RC3133)。
文摘The identification of indoor harmful gases is imperative due to their significant threats to human health and safety.To achieve accurate identification,an effective strategy of constructing a sensor array combined with the pattern recognition algorithm is employed.Carbon-based thin-film transistors are selected as the sensor array unit,with semiconductor carbon nanotubes(CNTs)within the TFT channels modified with different metals(Au,Cu and Ti)for selective responses to NH_(3),H_(2)S and HCHO,respectively.For accurate gas species identification,an identification mode that combines linear discriminant analysis algorithms and logistic regression classifier is developed.The test results demonstrate that by preprocessing the sensor array’s sensing data with the LDA algorithm and subsequently employing the LR classifier for identification,a 100%recognition rate can be achieved for three target gases(NH3,H2S and HCHO).This work provides significant guidance for future applications of chip-level gas sensors in the realms of the Internet of Things and Artificial Intelligence.
基金supported by National Natural Science Foundation of China under Grant No. 50534050the Key Project of the Chinese Academy of Sciences under Grant No. KJCX2-SW-W27.
文摘A room-temperature broadly tunable mid-infrared difference frequency laser source for highly sensitive trace gas detection has been developed recently in our laboratory. The mid-infrared laser system is based on quasi-phase-matched （QPM） difference frequency generation （DFG） in a multigrating, temperature-controlled periodically poled LiNbO3 （PPLN） crystal and employs two near-infrared diode lasers as pump sources. The mid-infrared coherent radiation generated is tunable from 3.2 μm to 3.7μm with an output power of about 100 μW. By changing one of the pump laser head with another wavelength range, we can readily obtain other needed mid-infrared wavelength range cover. The performance of the mid-infrared laser system and its application to highly sensitive spectroscopic detection of CH4, HCl, CH2O, and NO2 has been carried out. A multi-reflection White cell was used in the experiment gaining ppb-level sensitivity. The DFG laser system has the features of compact, room-temperature operation, narrow line-width, and broadly continuous tunable range for potential applications in industry and environmental monitoring.
基金financed by the Key Project of the National Research Program of China(grant No.2020YFB0606201).
文摘To investigate the non-uniform distribution of different gases passing through the parallel cyclones,experiments were conducted on a circulating fluidized bed(CFB)equipped with six asymmetrical cyclones.A multi-tracer gas method was used,with CO,O_(2),and CO_(2) chosen to represent gases with different properties in the flue gas at the inlets of the cyclones.The uniformity of multi-gas distribution was evaluated by measuring the concentration deviations of each tracer gas passing through individual cyclones.The results indicate that the concentrations of multi-tracer gases are higher in the middle cyclone among the three,which are located on the tracer gas injection side during the test of single-side secondary air(SA)tracing.The maximum concentration deviation of tracer gases is for CO_(2),while the minimum is for CO.At the three cyclone inlets on the opposite side,the tracer gas with higher density exhibits a more uniform distribution,and the gas uniformity decreases as the density decreases.The effects of superficial velocity,SA ratio,bed inventory,and tracer gas injection region on the uniformity of gas distribution were studied.The results show that superficial velocity and SA ratio primarily affect the uniformity of higher density gases,while bed inventory has a greater influence on lower density gases.The gas distributions are most non-uniform,especially for CO_(2),when the tracer gas injection region is near the rear wall closer to the induced draft fan during the test of regional SA tracing.
