A sensor,serving as a transducer,produces a quantifiable output in response to a predetermined input stimulus,which may be of a chemical or physical nature.The field of gas detection has experienced a substantial surg...A sensor,serving as a transducer,produces a quantifiable output in response to a predetermined input stimulus,which may be of a chemical or physical nature.The field of gas detection has experienced a substantial surge in research activity,attributable to the diverse functionalities and enhanced accessibility of advanced active materials.In this work,recent advances in gas sensors,specifically those utilizing Field Effect Transistors(FETs),are summarized,including device configurations,response characteristics,sensor materials,and application domains.In pursuing high-performance artificial olfactory systems,the evolution of FET gas sensors necessitates their synchronization with material advancements.These materials should have large surface areas to enhance gas adsorption,efficient conversion of gas input to detectable signals,and strong mechanical qualities.The exploration of gas-sensitive materials has covered diverse categories,such as organic semiconductor polymers,conductive organic compounds and polymers,metal oxides,metal-organic frameworks,and low-dimensional materials.The application of gas sensing technology holds significant promise in domains such as industrial safety,environmental monitoring,and medical diagnostics.This comprehensive review thoroughly examines recent progress,identifies prevailing technical challenges,and outlines prospects for gas detection technology utilizing field effect transistors.The primary aim is to provide a valuable reference for driving the development of the next generation of gas-sensitive monitoring and detection systems characterized by improved sensitivity,selectivity,and intelligence.展开更多
Electronic nose and thermal images are effective ways to diagnose the presence of gases in real-time realtime.Multimodal fusion of these modalities can result in the development of highly accurate diagnostic systems.T...Electronic nose and thermal images are effective ways to diagnose the presence of gases in real-time realtime.Multimodal fusion of these modalities can result in the development of highly accurate diagnostic systems.The low-cost thermal imaging software produces low-resolution thermal images in grayscale format,hence necessitating methods for improving the resolution and colorizing the images.The objective of this paper is to develop and train a super-resolution generative adversarial network for improving the resolution of the thermal images,followed by a sparse autoencoder for colorization of thermal images and amultimodal convolutional neural network for gas detection using electronic nose and thermal images.The dataset used comprises 6400 thermal images and electronic nose measurements for four classes.A multimodal Convolutional Neural Network(CNN)comprising an EfficientNetB2 pre-trainedmodel was developed using both early and late feature fusion.The Super Resolution Generative Adversarial Network(SRGAN)model was developed and trained on low and high-resolution thermal images.Asparse autoencoder was trained on the grayscale and colorized thermal images.The SRGAN was trained on lowand high-resolution thermal images,achieving a Structural Similarity Index(SSIM)of 90.28,a Peak Signal-to-Noise Ratio(PSNR)of 68.74,and a Mean Absolute Error(MAE)of 0.066.The autoencoder model produced an MAE of 0.035,a Mean Squared Error(MSE)of 0.006,and a Root Mean Squared Error(RMSE)of 0.0705.The multimodal CNN,trained on these images and electronic nose measurements using both early and late fusion techniques,achieved accuracies of 97.89% and 98.55%,respectively.Hence,the proposed framework can be of great aid for the integration with low-cost software to generate high quality thermal camera images and highly accurate detection of gases in real-time.展开更多
Nickel oxide(NiO)based gas sensors have at-tracted intense attention due to its high re-sponse to hydrogen sulfide(H_(2)S)gas.It has been demonstrated that the NiO sensors with exposed(111)facet exhibit excellent perf...Nickel oxide(NiO)based gas sensors have at-tracted intense attention due to its high re-sponse to hydrogen sulfide(H_(2)S)gas.It has been demonstrated that the NiO sensors with exposed(111)facet exhibit excellent perfor-mance,but the single-orientation NiO sensors with exposed(111)facet have rarely been studied.In this work,high quality(111)-ori-ented NiO epitaxial films were fabricated by pulsed laser deposition.Detailed crystalline structural information was revealed by using synchrotron based X-ray diffraction(XRD)technology.These NiO thin films show good se-lectivity for H_(2)S gas detection.Without further modification,the highest response to 100 ppm H_(2)S was measured to be 13.07 at 300℃,and limit of detection(LOD)could be as low as 186 ppb.Fitting of the electrical response curves during adsorption and desorption of H_(2)S gas indicates the two-site Langmuir kinetic processes.Combining with XPS and XAS measure-ments,the mechanism was discussed.Density functional theory(DFT)calculations show that NiO with exposed(111)facets has the most negative adsorption energy,indicating more sen-sitive to H_(2)S.These results could inspire more studies of metal oxide semiconductor-based gas sensors with specific surface.展开更多
Over the past decades,membrane-based separation processes have found numerous applications in various industries.Membrane contactor is an important part of the separation of dissolved gas in the early stage of gas det...Over the past decades,membrane-based separation processes have found numerous applications in various industries.Membrane contactor is an important part of the separation of dissolved gas in the early stage of gas detection.In this paper,to improve efficiency in the detection of the dissolved gas phase in seawater,a better flat membrane contactor is proposed to achieve efficient degassing,inspired by the way fish breathe underwater and the special structure of fish gills.The bioinspired flow channel structures in the flat membrane contactor are suggested along with the distribution of internal blood vessels in the gill platelet and the feature of the gill platelet surface.Using 3D printing,the special degassing devices are manufactured,and comparative analysis of relevant flow parameters is made using different flow channels,combined with the CFD simulation.The final result showed that the proposed flow channel in the degasser achieves a better degassing effect compared with conventional flow channel when the membrane contact area is limited,which can provide good conditions for subsequent gas detection.展开更多
Wavelength sweep technique （WST） is introduced into intra-cavity fiber laser （ICFL） for low concentration gas detection. The limitation induced by noise can be eliminated using this method, and the performance of ...Wavelength sweep technique （WST） is introduced into intra-cavity fiber laser （ICFL） for low concentration gas detection. The limitation induced by noise can be eliminated using this method, and the performance of the system is improved. The sensitivity of the system is reduced to less than 300 ppm. With WST, sweeping characteristic of the ICFL can be described according to known gas absorption spectra.展开更多
Effective methods are urgently required to optimize Raman spectroscopy technology to ameliorate its low detection sensitivity.Here,we superposed two near-concentric cavities to develop a dual near-concentric cavities ...Effective methods are urgently required to optimize Raman spectroscopy technology to ameliorate its low detection sensitivity.Here,we superposed two near-concentric cavities to develop a dual near-concentric cavities group(DNCCG)to assess its effect on gas Raman signal intensity,signal-to-noise ratio(SNR),and limit of detection(LOD).The results showed that DNCCG generally had higher CO_(2) Raman signal intensity than the sum of two near-concentric cavities.Meanwhile,the noise intensity of DNCCG was not enhanced by the superposition of near-concentric cavities.Accordingly,DNCCG increased the SNR.The LOD for CO_(2) was 24.6 parts per million.DNCCG could be an effective method to improve the detection capability of trace gases and broaden the dynamic detection range,which might aid the future development of innovative technology for multicomponent gas detection.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
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
Metal-organic frameworks(MOFs)have been extensively used for gas sorption,storage and separation owing to ultrahigh porosity,exceptional thermal stability,and wide structural diversity.However,when it comes to ultra-l...Metal-organic frameworks(MOFs)have been extensively used for gas sorption,storage and separation owing to ultrahigh porosity,exceptional thermal stability,and wide structural diversity.However,when it comes to ultra-low concentration gas detection,technical bottlenecks of MOFs appear due to the poor adsorption capacity at ppm-/ppblevel concentration and the limited sensitivity for signal transduction.Here,we present hybrid MOF-polymer physi-chemisorption mechanisms integrated with infrared(IR)nanoantennas for highly selective and ultrasensitive CO_(2) detection.To improve the adsorption capacity for trace amounts of gas molecules,MOFs are decorated with amino groups to introduce the chemisorption while maintaining the structural integrity for physisorption.Additionally,leveraging all major optimization methods,a multi-hotspot strategy is proposed to improve the sensitivity of nanoantennas by enhancing the near field and engineering the radiative and absorptive loss.As a benefit,we demonstrate the competitive advantages of our strategy against the state-of-the-art miniaturized IR CO_(2) sensors,including low detection limit,high sensitivity(0.18%/ppm),excellent reversibility(variation within 2%),and high selectivity(against C_(2)H_(5)OH,CH_(3)OH,N_(2)).This work provides valuable insights into the integration of advanced porous materials and nanophotonic devices,which can be further adopted in ultra-low concentration gas monitoring in industry and environmental applications.展开更多
To find a neural network model suitable to identify the concentration of mixed pernicious gases in pig house, the quantitative detection model of pernicious gases in pig house was set up based on BP （ Back propagatio...To find a neural network model suitable to identify the concentration of mixed pernicious gases in pig house, the quantitative detection model of pernicious gases in pig house was set up based on BP （ Back propagation） neural network. The BP neural network was trained separately by the three functions, trainbr, traingdm and trainlm, in order to identify the concentration of mixed pernicious gases composed of ammonia gas and hepatic gas. The neural network toolbox in MATLAB software was used to simulate the detection. The results showed that the neural network trained by trainbr function has high average identification accuracy and faster detection speed, and it is also insensitive to noise; therefore, it is suitable to identify the concentration of pemidous gases in pig house. These data provide a reference for intelligent monitoring of pemicious gases in pigsty.展开更多
Here,we report a Pd/PdO_(x) sensing material that achieves 1-s detection of 4% H_(2) gas(i.e.,the lower explosive limit concentration for H_(2))at room temperature in air.The Pd/PdO_(x) material is a network of interc...Here,we report a Pd/PdO_(x) sensing material that achieves 1-s detection of 4% H_(2) gas(i.e.,the lower explosive limit concentration for H_(2))at room temperature in air.The Pd/PdO_(x) material is a network of interconnected nanoscopic domains of Pd,PdO,and PdO_(2).Upon exposure to 4% H_(2),PdO and PdO_(2) in the Pd/PdO_(x) are immediately reduced to metallic Pd,generating over a>90% drop in electrical resistance.The mechanistic study reveals that the Pd/PdO_(2) interface in Pd/PdOx is responsible for the ultrafast PdO_(x) reduction.Metallic Pd at the Pd/PdO_(2) interface enables fast H_(2) dissociation to adsorbed H atoms,significantly lowering the PdO2 reduction barrier.In addition,control experiments suggest that the interconnectivity of Pd,PdO,and PdO2 in our Pd/PdO_(x) sensing material further facilitates the reduction of PdO,which would otherwise not occur.The 1-s response time of Pd/PdO_(x) under ambient conditions makes it an excellent alarm for the timely detection of hydrogen gas leaks.展开更多
The feasibility of gas kick early detection outside the riser was analyzed based on gas-liquid multiphase flow theory.Then an experimental platform for gas kick early detection based on Doppler ultrasonic wave was est...The feasibility of gas kick early detection outside the riser was analyzed based on gas-liquid multiphase flow theory.Then an experimental platform for gas kick early detection based on Doppler ultrasonic wave was established and the propagation experiments in two-phase flow of gas-water(sucrose solutions)were conducted.The time and frequency domains of the Doppler ultrasonic wave signals during the experiments were analyzed.The results show that:(1)No matter the pump was on or off,the detected average Doppler ultrasonic signal voltage increased first and then decreased with the increase of the gas void fraction,and had a quadratic function relation with gas void fraction,so the average voltage change of the monitored signals can be used to deduce the approximate gas void fraction.The Doppler ultrasonic wave signal voltage was significantly reduced in magnitude and variation in the solution with higher viscosity,and the viscosity has stronger impact on the magnitude of signal than density.(2)When the pump was stopped,the Doppler shift increased with the increase of gas void fraction,and the two showed a nearly linear relation,so the detected amount of Doppler shift can reflect the variation of gas void fraction quantitatively.When the pump was on,the sound energy produced by frequency converter had a more significant impact on amplitude spectrum than gas void fraction,so it is impossible to determine whether gas kick occurs by frequency domain signal analysis.(3)This method is a non-contact measurement,with no contact with the drilling fluid and no disruption to the drilling operation.It can quantitatively characterize the gas void fraction according to the change of Doppler ultrasonic signal,enabling earlier detection of gas kick.展开更多
Sulfur dioxide has been found to decrease the chemiluminescence of luminol-iodine system.A new determination method for sulfur dioxide in atmosphere is developed by applying this reaction to a flow injection gas diffu...Sulfur dioxide has been found to decrease the chemiluminescence of luminol-iodine system.A new determination method for sulfur dioxide in atmosphere is developed by applying this reaction to a flow injection gas diffusion separation system.This permits the determination of sulfur dioxide selectively and rapidly.展开更多
Acetone is a widely used volatile organic compound in various industries,and several gas sensors have been developed for its detection and real-time monitoring.This study reported a novel method for determining the ac...Acetone is a widely used volatile organic compound in various industries,and several gas sensors have been developed for its detection and real-time monitoring.This study reported a novel method for determining the acetone vapor concentration based on correlated laser speckles using polymer-dispersed liquid crystals(PDLCs).Here,PDLC films comprising a mixture of the thermotropic nematic liquid crystal(LC)and ultraviolet-curable polymers were fabricated using different LC mass ratios and ultraviolet curing conditions.The laser beam was transmitted through the PDLC film to generate scattered light and speckles.When the PDLC film was exposed to the acetone vapor,the acetone molecules diffused into the PDLC film and interacted with the LC molecules,modifying the orientation of the LC molecules and the equivalent refractive index of the LC droplets.This in turn decreased the correlation coefficient of the speckle images.The experimental results indicated that the PDLC gas sensor was selectively sensitive to different concentrations of the acetone vapor,ranging from 1800 ppm to 3200 ppm.In comparison with traditional LC gas sensors that use a polarizing microscope to detect the change in brightness of the modulated light field,the proposed method is simpler,less expensive,and more robust under external disturbances such as vibrations.展开更多
Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and...Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.展开更多
In this work,the interconnected graphene scaffolds are prepared by three-dimensional(3 D)printing for multifunctional gas detection with tunable sensitivity.The scaffolds with regularly aligned graphene conductive net...In this work,the interconnected graphene scaffolds are prepared by three-dimensional(3 D)printing for multifunctional gas detection with tunable sensitivity.The scaffolds with regularly aligned graphene conductive networks exhibit significant mechanical strength and high electrical stability to multi-direction deformation,which can be attributed to the typical core-shell structure of graphene and PVP.The resistance of the free-standing scaffolds can realize the real-time response to H_(2) O and NO_(2),and the relative resistance change to 100 ppm H_(2) O and 100 ppm NO_(2) can reach 2%and 2.5%,respectively.The charge doping of the oxidizing gases is considered to be the main reason for various response sensitivities of the scaffolds with different orthogonal layers,in which the interconnected conductive network can generate a large specific surface area and significantly improving the adsorption of the target gases and the transfer of charge.The controllable fabrication of regular structure has appropriately great potential for further optimizations and applications in gas detection.展开更多
Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive mea...Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive measurement method to detect the development process of the overlying strata mining-induced fractures and their contained water quality in underground coal mining, which not only innovates a more simple-fast-reliable detection method, but also further expands the applications of radon gas detection technology in mining field. A 3D simulation design of comprehensive testing system for detecting strata mining-induced fractures on surface with radon gas (CTSR) was carried out by using a large-scale 3D solid model design software Pro/Engineer (Pro/E), which overcame three main disadvantages of ''static design thought, 2D planar design and heavy workload for remodification design'' on exiting design for mining engineering test systems. Meanwhile, based on the simulation design results of Pro/E software, the sta- bility of the jack-screw pressure bar for the key component in CTSR was checked with a material mechan- ics theory, which provided a reliable basis for materials selection during the latter machining process.展开更多
Wavelength modulation technique （WMT） and wavelength sweep technique （WST） are introduced into intra-cavity absorption gas sensors （ICAGS） for low concentration gas detection. The optimized parameters of the sys...Wavelength modulation technique （WMT） and wavelength sweep technique （WST） are introduced into intra-cavity absorption gas sensors （ICAGS） for low concentration gas detection. The optimized parameters of the system maximizing the signal-to-noise ratio （SNR） are found. Calibration of acetylene concentration and gas recognition are both realized.展开更多
In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according ...In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according to contact various gas samples (as strong acid and base, chloroform, ammonia and HF) of this dye-coated nonwoven film was examined for the application of chemically toxic materials detecting tools in the actual site of working place without aid of any kinds of detecting devices. By the addition of electron transfer agent (quinone derivatives), quick color change behaviors were observed within 10 seconds under the contact of various toxic gases in general condition(room temperature, 50% humidity).展开更多
基金supported by the National Key R&D Program of China(No.2023YFC3707201)the National Natural Science Foundation of China(No.52320105003)+2 种基金the Informatization Plan of Chinese Academy of Sciences(No.CAS-WX2023PY-0103)the Fundamental Research Funds for the Central Universities(No.E3ET1803)sponsored by the Alliance of International Science Organizations(ANSO)scholarship for young talents.
文摘A sensor,serving as a transducer,produces a quantifiable output in response to a predetermined input stimulus,which may be of a chemical or physical nature.The field of gas detection has experienced a substantial surge in research activity,attributable to the diverse functionalities and enhanced accessibility of advanced active materials.In this work,recent advances in gas sensors,specifically those utilizing Field Effect Transistors(FETs),are summarized,including device configurations,response characteristics,sensor materials,and application domains.In pursuing high-performance artificial olfactory systems,the evolution of FET gas sensors necessitates their synchronization with material advancements.These materials should have large surface areas to enhance gas adsorption,efficient conversion of gas input to detectable signals,and strong mechanical qualities.The exploration of gas-sensitive materials has covered diverse categories,such as organic semiconductor polymers,conductive organic compounds and polymers,metal oxides,metal-organic frameworks,and low-dimensional materials.The application of gas sensing technology holds significant promise in domains such as industrial safety,environmental monitoring,and medical diagnostics.This comprehensive review thoroughly examines recent progress,identifies prevailing technical challenges,and outlines prospects for gas detection technology utilizing field effect transistors.The primary aim is to provide a valuable reference for driving the development of the next generation of gas-sensitive monitoring and detection systems characterized by improved sensitivity,selectivity,and intelligence.
基金funded by the Centre for Advanced Modelling and Geospatial Information Systems(CAMGIS),Faculty of Engineering and IT,University of Technology Sydneysupported by the Researchers Supporting Project,King Saud University,Riyadh,Saudi Arabia,under Project RSP2025 R14.
文摘Electronic nose and thermal images are effective ways to diagnose the presence of gases in real-time realtime.Multimodal fusion of these modalities can result in the development of highly accurate diagnostic systems.The low-cost thermal imaging software produces low-resolution thermal images in grayscale format,hence necessitating methods for improving the resolution and colorizing the images.The objective of this paper is to develop and train a super-resolution generative adversarial network for improving the resolution of the thermal images,followed by a sparse autoencoder for colorization of thermal images and amultimodal convolutional neural network for gas detection using electronic nose and thermal images.The dataset used comprises 6400 thermal images and electronic nose measurements for four classes.A multimodal Convolutional Neural Network(CNN)comprising an EfficientNetB2 pre-trainedmodel was developed using both early and late feature fusion.The Super Resolution Generative Adversarial Network(SRGAN)model was developed and trained on low and high-resolution thermal images.Asparse autoencoder was trained on the grayscale and colorized thermal images.The SRGAN was trained on lowand high-resolution thermal images,achieving a Structural Similarity Index(SSIM)of 90.28,a Peak Signal-to-Noise Ratio(PSNR)of 68.74,and a Mean Absolute Error(MAE)of 0.066.The autoencoder model produced an MAE of 0.035,a Mean Squared Error(MSE)of 0.006,and a Root Mean Squared Error(RMSE)of 0.0705.The multimodal CNN,trained on these images and electronic nose measurements using both early and late fusion techniques,achieved accuracies of 97.89% and 98.55%,respectively.Hence,the proposed framework can be of great aid for the integration with low-cost software to generate high quality thermal camera images and highly accurate detection of gases in real-time.
基金supported by the National Key Research and Development Program of China(No.2022YFA1603902)the National Natural Science Foundation of China(No.12175235,No.62271462,and No.12004407)。
文摘Nickel oxide(NiO)based gas sensors have at-tracted intense attention due to its high re-sponse to hydrogen sulfide(H_(2)S)gas.It has been demonstrated that the NiO sensors with exposed(111)facet exhibit excellent perfor-mance,but the single-orientation NiO sensors with exposed(111)facet have rarely been studied.In this work,high quality(111)-ori-ented NiO epitaxial films were fabricated by pulsed laser deposition.Detailed crystalline structural information was revealed by using synchrotron based X-ray diffraction(XRD)technology.These NiO thin films show good se-lectivity for H_(2)S gas detection.Without further modification,the highest response to 100 ppm H_(2)S was measured to be 13.07 at 300℃,and limit of detection(LOD)could be as low as 186 ppb.Fitting of the electrical response curves during adsorption and desorption of H_(2)S gas indicates the two-site Langmuir kinetic processes.Combining with XPS and XAS measure-ments,the mechanism was discussed.Density functional theory(DFT)calculations show that NiO with exposed(111)facets has the most negative adsorption energy,indicating more sen-sitive to H_(2)S.These results could inspire more studies of metal oxide semiconductor-based gas sensors with specific surface.
基金funded by Science-Technology Development Plan Project of Jilin Province,20210203099SF,Zhiyong ChangScience and Technology Development Project of Jilin Province,20190303061SF,Yongming Yao13th Five-Year Plan Scientific Research Foundation of the Education Department of Jilin Province,JJKH20190190KJ,Zhiyong Chang.
文摘Over the past decades,membrane-based separation processes have found numerous applications in various industries.Membrane contactor is an important part of the separation of dissolved gas in the early stage of gas detection.In this paper,to improve efficiency in the detection of the dissolved gas phase in seawater,a better flat membrane contactor is proposed to achieve efficient degassing,inspired by the way fish breathe underwater and the special structure of fish gills.The bioinspired flow channel structures in the flat membrane contactor are suggested along with the distribution of internal blood vessels in the gill platelet and the feature of the gill platelet surface.Using 3D printing,the special degassing devices are manufactured,and comparative analysis of relevant flow parameters is made using different flow channels,combined with the CFD simulation.The final result showed that the proposed flow channel in the degasser achieves a better degassing effect compared with conventional flow channel when the membrane contact area is limited,which can provide good conditions for subsequent gas detection.
基金supported by the National Natural Science Foundation of China under Grant No. 60577013the New Century Support Program for Talented Young Teachers in Universities under Grant No. NCET-04-0241
文摘Wavelength sweep technique （WST） is introduced into intra-cavity fiber laser （ICFL） for low concentration gas detection. The limitation induced by noise can be eliminated using this method, and the performance of the system is improved. The sensitivity of the system is reduced to less than 300 ppm. With WST, sweeping characteristic of the ICFL can be described according to known gas absorption spectra.
基金This work was supported by the High-end Foreign Experts Introduction Plan(No.G2021003003L)the Hebei Province Introduced Foreign Intelligence Projects(No.2022-18).
文摘Effective methods are urgently required to optimize Raman spectroscopy technology to ameliorate its low detection sensitivity.Here,we superposed two near-concentric cavities to develop a dual near-concentric cavities group(DNCCG)to assess its effect on gas Raman signal intensity,signal-to-noise ratio(SNR),and limit of detection(LOD).The results showed that DNCCG generally had higher CO_(2) Raman signal intensity than the sum of two near-concentric cavities.Meanwhile,the noise intensity of DNCCG was not enhanced by the superposition of near-concentric cavities.Accordingly,DNCCG increased the SNR.The LOD for CO_(2) was 24.6 parts per million.DNCCG could be an effective method to improve the detection capability of trace gases and broaden the dynamic detection range,which might aid the future development of innovative technology for multicomponent gas detection.
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.
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This work is supported by the RIE Advanced Manufacturing and Engineering(AME)Programmatic Grant Project(Grant A18A5b0056,WBS:A-0005117-02-00)the Advanced Research and Technology Innovation Centre(ARTIC)Project(WBS:A-0005947-20-00)the Ministry of Education(MOE)of Singapore Tier 1 Project(WBS:A-0005138-01-00).
文摘Metal-organic frameworks(MOFs)have been extensively used for gas sorption,storage and separation owing to ultrahigh porosity,exceptional thermal stability,and wide structural diversity.However,when it comes to ultra-low concentration gas detection,technical bottlenecks of MOFs appear due to the poor adsorption capacity at ppm-/ppblevel concentration and the limited sensitivity for signal transduction.Here,we present hybrid MOF-polymer physi-chemisorption mechanisms integrated with infrared(IR)nanoantennas for highly selective and ultrasensitive CO_(2) detection.To improve the adsorption capacity for trace amounts of gas molecules,MOFs are decorated with amino groups to introduce the chemisorption while maintaining the structural integrity for physisorption.Additionally,leveraging all major optimization methods,a multi-hotspot strategy is proposed to improve the sensitivity of nanoantennas by enhancing the near field and engineering the radiative and absorptive loss.As a benefit,we demonstrate the competitive advantages of our strategy against the state-of-the-art miniaturized IR CO_(2) sensors,including low detection limit,high sensitivity(0.18%/ppm),excellent reversibility(variation within 2%),and high selectivity(against C_(2)H_(5)OH,CH_(3)OH,N_(2)).This work provides valuable insights into the integration of advanced porous materials and nanophotonic devices,which can be further adopted in ultra-low concentration gas monitoring in industry and environmental applications.
文摘To find a neural network model suitable to identify the concentration of mixed pernicious gases in pig house, the quantitative detection model of pernicious gases in pig house was set up based on BP （ Back propagation） neural network. The BP neural network was trained separately by the three functions, trainbr, traingdm and trainlm, in order to identify the concentration of mixed pernicious gases composed of ammonia gas and hepatic gas. The neural network toolbox in MATLAB software was used to simulate the detection. The results showed that the neural network trained by trainbr function has high average identification accuracy and faster detection speed, and it is also insensitive to noise; therefore, it is suitable to identify the concentration of pemidous gases in pig house. These data provide a reference for intelligent monitoring of pemicious gases in pigsty.
基金The work at Wayne State University and the Pacific Northwest National Laboratory was supported by the U.S.Department of Energy(DOE),Office of Science,Office of Basic Energy Sciences,through Award#78705In addition,L.L.and X.G.acknowledge support from National Science Foundation under award CHE-1943737.L.Z.and S.W.L.acknowledge support from the National Natural Science Foundation of China(No.22103047)Hefei National Laboratory for Physical Sciences at the Microscale(No.KF2020107).
文摘Here,we report a Pd/PdO_(x) sensing material that achieves 1-s detection of 4% H_(2) gas(i.e.,the lower explosive limit concentration for H_(2))at room temperature in air.The Pd/PdO_(x) material is a network of interconnected nanoscopic domains of Pd,PdO,and PdO_(2).Upon exposure to 4% H_(2),PdO and PdO_(2) in the Pd/PdO_(x) are immediately reduced to metallic Pd,generating over a>90% drop in electrical resistance.The mechanistic study reveals that the Pd/PdO_(2) interface in Pd/PdOx is responsible for the ultrafast PdO_(x) reduction.Metallic Pd at the Pd/PdO_(2) interface enables fast H_(2) dissociation to adsorbed H atoms,significantly lowering the PdO2 reduction barrier.In addition,control experiments suggest that the interconnectivity of Pd,PdO,and PdO2 in our Pd/PdO_(x) sensing material further facilitates the reduction of PdO,which would otherwise not occur.The 1-s response time of Pd/PdO_(x) under ambient conditions makes it an excellent alarm for the timely detection of hydrogen gas leaks.
基金Supported by Natural Science Foundation of China(51991363)National Program on Key Basic Research Project(973 Program)(2015CB251200)Changjiang Scholars and Innovative Research Team Project(IRT_14R58)
文摘The feasibility of gas kick early detection outside the riser was analyzed based on gas-liquid multiphase flow theory.Then an experimental platform for gas kick early detection based on Doppler ultrasonic wave was established and the propagation experiments in two-phase flow of gas-water(sucrose solutions)were conducted.The time and frequency domains of the Doppler ultrasonic wave signals during the experiments were analyzed.The results show that:(1)No matter the pump was on or off,the detected average Doppler ultrasonic signal voltage increased first and then decreased with the increase of the gas void fraction,and had a quadratic function relation with gas void fraction,so the average voltage change of the monitored signals can be used to deduce the approximate gas void fraction.The Doppler ultrasonic wave signal voltage was significantly reduced in magnitude and variation in the solution with higher viscosity,and the viscosity has stronger impact on the magnitude of signal than density.(2)When the pump was stopped,the Doppler shift increased with the increase of gas void fraction,and the two showed a nearly linear relation,so the detected amount of Doppler shift can reflect the variation of gas void fraction quantitatively.When the pump was on,the sound energy produced by frequency converter had a more significant impact on amplitude spectrum than gas void fraction,so it is impossible to determine whether gas kick occurs by frequency domain signal analysis.(3)This method is a non-contact measurement,with no contact with the drilling fluid and no disruption to the drilling operation.It can quantitatively characterize the gas void fraction according to the change of Doppler ultrasonic signal,enabling earlier detection of gas kick.
文摘Sulfur dioxide has been found to decrease the chemiluminescence of luminol-iodine system.A new determination method for sulfur dioxide in atmosphere is developed by applying this reaction to a flow injection gas diffusion separation system.This permits the determination of sulfur dioxide selectively and rapidly.
基金supported by the Key Research and Development Program of Shanxi Province,China(Grant No.202102030201002)the Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT_17R70)+2 种基金the State Key Program of National Natural Science of China(Grant No.11434007)the 111 Project,China(Grant No.D18001)the Fund for Shanxi“1331 Project”Key Subjects Construction,China.
文摘Acetone is a widely used volatile organic compound in various industries,and several gas sensors have been developed for its detection and real-time monitoring.This study reported a novel method for determining the acetone vapor concentration based on correlated laser speckles using polymer-dispersed liquid crystals(PDLCs).Here,PDLC films comprising a mixture of the thermotropic nematic liquid crystal(LC)and ultraviolet-curable polymers were fabricated using different LC mass ratios and ultraviolet curing conditions.The laser beam was transmitted through the PDLC film to generate scattered light and speckles.When the PDLC film was exposed to the acetone vapor,the acetone molecules diffused into the PDLC film and interacted with the LC molecules,modifying the orientation of the LC molecules and the equivalent refractive index of the LC droplets.This in turn decreased the correlation coefficient of the speckle images.The experimental results indicated that the PDLC gas sensor was selectively sensitive to different concentrations of the acetone vapor,ranging from 1800 ppm to 3200 ppm.In comparison with traditional LC gas sensors that use a polarizing microscope to detect the change in brightness of the modulated light field,the proposed method is simpler,less expensive,and more robust under external disturbances such as vibrations.
基金Supported by the National Natural Science Foundation of China(51474184)the Natural Science Foundation of the State Administration of Work Safety in China(2012-387,Sichuan-0021-2016AQ)
文摘Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.
基金sponsored by the National Natural Science Foundation of China(No.51772310)the CAS Pioneer Hundred Talents Program+2 种基金Shanghai Pujiang Program(No.17PJ1410100)the Young Elite Scientist Sponsorship Program by CAST(No.2017QNRC001)the Shanghai Institute of Ceramics Innovative Funding。
文摘In this work,the interconnected graphene scaffolds are prepared by three-dimensional(3 D)printing for multifunctional gas detection with tunable sensitivity.The scaffolds with regularly aligned graphene conductive networks exhibit significant mechanical strength and high electrical stability to multi-direction deformation,which can be attributed to the typical core-shell structure of graphene and PVP.The resistance of the free-standing scaffolds can realize the real-time response to H_(2) O and NO_(2),and the relative resistance change to 100 ppm H_(2) O and 100 ppm NO_(2) can reach 2%and 2.5%,respectively.The charge doping of the oxidizing gases is considered to be the main reason for various response sensitivities of the scaffolds with different orthogonal layers,in which the interconnected conductive network can generate a large specific surface area and significantly improving the adsorption of the target gases and the transfer of charge.The controllable fabrication of regular structure has appropriately great potential for further optimizations and applications in gas detection.
基金support for this work provided by the Fundamental Research Funds for the Central Universities(China University of Mining & Technology) (No. 2010ZDP02B02)the State Key Laboratory of Coal Resources and Safe Mining(No. SKLCRSM08X02)
文摘Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive measurement method to detect the development process of the overlying strata mining-induced fractures and their contained water quality in underground coal mining, which not only innovates a more simple-fast-reliable detection method, but also further expands the applications of radon gas detection technology in mining field. A 3D simulation design of comprehensive testing system for detecting strata mining-induced fractures on surface with radon gas (CTSR) was carried out by using a large-scale 3D solid model design software Pro/Engineer (Pro/E), which overcame three main disadvantages of ''static design thought, 2D planar design and heavy workload for remodification design'' on exiting design for mining engineering test systems. Meanwhile, based on the simulation design results of Pro/E software, the sta- bility of the jack-screw pressure bar for the key component in CTSR was checked with a material mechan- ics theory, which provided a reliable basis for materials selection during the latter machining process.
基金supported by the National Natural Science Foundation of China under Grant No. 60577013the New Century Support Program for Talented Young Teachers in Universities, MOE (Ministry of Education of China), China
文摘Wavelength modulation technique （WMT） and wavelength sweep technique （WST） are introduced into intra-cavity absorption gas sensors （ICAGS） for low concentration gas detection. The optimized parameters of the system maximizing the signal-to-noise ratio （SNR） are found. Calibration of acetylene concentration and gas recognition are both realized.
文摘In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according to contact various gas samples (as strong acid and base, chloroform, ammonia and HF) of this dye-coated nonwoven film was examined for the application of chemically toxic materials detecting tools in the actual site of working place without aid of any kinds of detecting devices. By the addition of electron transfer agent (quinone derivatives), quick color change behaviors were observed within 10 seconds under the contact of various toxic gases in general condition(room temperature, 50% humidity).
