Off-axis integrated cavity output spectroscopy(OA-ICOS)is an extremely sensitive technique for measuring trace gas concentrations.Nevertheless,recent research has indicated that when the reflectivity of the mirrors fo...Off-axis integrated cavity output spectroscopy(OA-ICOS)is an extremely sensitive technique for measuring trace gas concentrations.Nevertheless,recent research has indicated that when the reflectivity of the mirrors forming the cavity is excessively high,it affects the linearity between the absorption signal and concentration.In this study,the causes and limitations of this phenomenon are discussed based on the Beer-Lambert law and the law of light propagation within the cavity.A new equation is derived to describe the nonlinear relationship between the integral area of absorption spectra and gas concentration.The absorption spectra of CO_(2)and CH_(4),measured under different experimental conditions and concentrations,were fitted with Voigt functions to obtain parameters such as peak values and integral areas,which were used to verify the theoretical derivation process and results.The experimental results demonstrate that the relationship between the area of the measured absorption spectra and the gas concentration is consistent with the new formula,with an average fitting correlation coefficient of 0.9998.Meanwhile,the experimental results also demonstrate that the effective optical path length indeed decreases with increasing concentration.Furthermore,the cavity reflectances(99.99644%at 6242.6 cm^(-1)and 99.99833%at 6046.96 cm^(-1))derived from the fitting coefficient of the new concentration expression closely match the reflectances(99.99727%at 6242.6 cm^(-1)and 99.99868%at 6046.96 cm^(-1))obtained by applying the classical formula to the spectra of the lowest gas concentration.These experimental results validate the theoretical deduction process and expression.This research provides insights for the theoretical and practical advancements of OA-ICOS,which is significant for advancing high-precision trace gas detection technology.展开更多
Exploring the nonlinear relationship between air pollution and precursor emissions in Qingdao,eastern China is crucial for improving air quality.We simulated 32 emission reduction scenarios based on different volatile...Exploring the nonlinear relationship between air pollution and precursor emissions in Qingdao,eastern China is crucial for improving air quality.We simulated 32 emission reduction scenarios based on different volatile organic compound(VOC)and nitrogen oxide(NO_(x))emission reduction ratios using the Weather Research and Forecasting-Comprehensive Air Quality Model Extensions model.The emission reduction of VOCs was beneficial for reducing fine particulate matter(PM_(2.5))concentration in January and ozone(O_(3))concentration in June.However,NO_(x)must be reduced by at least 48%and 70%to decrease PM_(2.5)and O_(3)concentrations,respectively,when VOCs are not reduced.The responses of PM_(2.5)and O_(3)concentrations to emission reductions from different sources were also evaluated.The reduction in VOC emissions from different sources decreased the PM_(2.5)concentration in January,and O_(3)concertation in June,while NO_(x)reduction resulted in an increase.Controlling VOC emissions from industry has a positive effect on improving local PM_(2.5)and O_(3),while the emission reductions of NO_(x)from transportation and industry are not conducive to reducing PM_(2.5)and O_(3)concentrations.The synergistic emission reduction pathways for NO_(x)and VOCs during PM_(2.5)and O_(3)combined pollution were also analyzed.The VOC and NO_(x)emission reductions were beneficial for reducing the comprehensive Air Quality Index(sAQI)values.When the NO_(x)emission reduction was large,the sAQI improvement gradually exceeded that of VOCs.A collaborative optimization path should be adopted that focuses on controlling VOCs first,and further control of combined pollution should depend on the deep reduction of NO_(x).展开更多
In this paper, a simple nonlinear Maxwell model consisting of a nonlinear spring connected in series with a nonlinear dashpot obeying a power-law with constant material parameters, for representing successfully the ti...In this paper, a simple nonlinear Maxwell model consisting of a nonlinear spring connected in series with a nonlinear dashpot obeying a power-law with constant material parameters, for representing successfully the time-dependent properties of a variety of viscoelastic materials, is proposed. Numerical examples are performed to illustrate the sensitivity of the model to material parameters.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62005108 and 62205134)Xuzhou Science and Technology Plan Project(Grant No.KC23078)the Research and Innovation Plan for Graduate Students in Jiangsu Province,China(Grant Nos.KYCX253165 and KYCX243016)。
文摘Off-axis integrated cavity output spectroscopy(OA-ICOS)is an extremely sensitive technique for measuring trace gas concentrations.Nevertheless,recent research has indicated that when the reflectivity of the mirrors forming the cavity is excessively high,it affects the linearity between the absorption signal and concentration.In this study,the causes and limitations of this phenomenon are discussed based on the Beer-Lambert law and the law of light propagation within the cavity.A new equation is derived to describe the nonlinear relationship between the integral area of absorption spectra and gas concentration.The absorption spectra of CO_(2)and CH_(4),measured under different experimental conditions and concentrations,were fitted with Voigt functions to obtain parameters such as peak values and integral areas,which were used to verify the theoretical derivation process and results.The experimental results demonstrate that the relationship between the area of the measured absorption spectra and the gas concentration is consistent with the new formula,with an average fitting correlation coefficient of 0.9998.Meanwhile,the experimental results also demonstrate that the effective optical path length indeed decreases with increasing concentration.Furthermore,the cavity reflectances(99.99644%at 6242.6 cm^(-1)and 99.99833%at 6046.96 cm^(-1))derived from the fitting coefficient of the new concentration expression closely match the reflectances(99.99727%at 6242.6 cm^(-1)and 99.99868%at 6046.96 cm^(-1))obtained by applying the classical formula to the spectra of the lowest gas concentration.These experimental results validate the theoretical deduction process and expression.This research provides insights for the theoretical and practical advancements of OA-ICOS,which is significant for advancing high-precision trace gas detection technology.
基金funded by the Shandong Postdoctoral Science Foundation(No.SDCX-ZG-202303008).
文摘Exploring the nonlinear relationship between air pollution and precursor emissions in Qingdao,eastern China is crucial for improving air quality.We simulated 32 emission reduction scenarios based on different volatile organic compound(VOC)and nitrogen oxide(NO_(x))emission reduction ratios using the Weather Research and Forecasting-Comprehensive Air Quality Model Extensions model.The emission reduction of VOCs was beneficial for reducing fine particulate matter(PM_(2.5))concentration in January and ozone(O_(3))concentration in June.However,NO_(x)must be reduced by at least 48%and 70%to decrease PM_(2.5)and O_(3)concentrations,respectively,when VOCs are not reduced.The responses of PM_(2.5)and O_(3)concentrations to emission reductions from different sources were also evaluated.The reduction in VOC emissions from different sources decreased the PM_(2.5)concentration in January,and O_(3)concertation in June,while NO_(x)reduction resulted in an increase.Controlling VOC emissions from industry has a positive effect on improving local PM_(2.5)and O_(3),while the emission reductions of NO_(x)from transportation and industry are not conducive to reducing PM_(2.5)and O_(3)concentrations.The synergistic emission reduction pathways for NO_(x)and VOCs during PM_(2.5)and O_(3)combined pollution were also analyzed.The VOC and NO_(x)emission reductions were beneficial for reducing the comprehensive Air Quality Index(sAQI)values.When the NO_(x)emission reduction was large,the sAQI improvement gradually exceeded that of VOCs.A collaborative optimization path should be adopted that focuses on controlling VOCs first,and further control of combined pollution should depend on the deep reduction of NO_(x).
文摘In this paper, a simple nonlinear Maxwell model consisting of a nonlinear spring connected in series with a nonlinear dashpot obeying a power-law with constant material parameters, for representing successfully the time-dependent properties of a variety of viscoelastic materials, is proposed. Numerical examples are performed to illustrate the sensitivity of the model to material parameters.
