Publications by authors named "Minguang Gao"

In a Fourier transform infrared (IR) spectrometer, the Michelson interference signal extrapolation method based on linear prediction is often used to improve spectral resolution. In this method, an autoregressive (AR) model is established for the Michelson interference signal in the spectrometer. Once the AR model parameters are determined, the AR process is predictable.

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The aim of this study was to develop a quantitative analytical method to measure the effective components in the left cetirizine hydrochloride tablets using near infrared spectroscopy combining with a partial least square (PLS) analysis model. The method was internal cross-validated to determine the best wavelength range, spectral preprocessing methods and the optimal number of principal components. The concentration of validation set samples was predictable by PLS model.

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The four kinds of the structure characteristics of rotary type interferometer are mainly analyzed from the classical Michelson interferometer structure in the paper. The Optical path difference between the interferometer and the rotation angle is also analyzed. By setting parameters, the four kinds of rotary type optical path difference of the interferometer are simulated based on the optical path difference formula.

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A method of fast nondestructive determination of three kinds of water-soluble inorganic ions including SO₄²⁻, NO₃⁻ NH₄⁺ in aerosol was disscussed. The method of IC measurement values was used on the control of the three kinds of inorganic ion content. The quantitative calibration models of the inorganic ions were developed by using ATR-FTIR spectroscopy combined with PLS algorithm and the model was evaluated.

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Fourier transform infrared spectrometer can be realized in high temperature flue gas multicomponent measurement at the same time, has wide application prospects in the field. And one of the important factors to determine the success of application, lies in the measuring system of infrared interference figure sampling phase error control. This paper discusses the main-reasons of the appearance of phase error in the system, through the analysis of Helium-neon laser interference signal zero uniformity, illustrates the produce phase error is the main reason of the laser signal and reference signal phase difference.

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In order to observe two kinds of greenhouse gases, CO2 and CH4, making the biggest contribution to global warming, a ground-based Fourier transform near-infrared spectral remote sensing system was developed to record the perpendicular incidence sun spectra from February 2012 to April 2013 in Hefei continuously. The measured total transmittances in the atmosphere were obtained from perpendicular incidence sun spectra. Methods of line-by-line and low-order polynomial approximation were used to model the total atmospheric transmittances in forward model.

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Article Synopsis
  • NECL (Noise Equivalent Contrast Level) is essential for determining the sensitivity and limit of detection of infrared passive remote sensing systems, particularly in monitoring pollution.
  • The theoretical model shows that NECL is influenced by factors like NESR (Noise Equivalent Spectral Radiance), brightness temperatures of both the background and pollutants, and the absorption coefficients of the pollutants.
  • Results from sensing SF6 revealed that NECL significantly decreases with a greater temperature difference between the background and the pollution gas, with notable changes when the difference reaches 30 K, aided by false color images for better visualization of detection limits.
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Airborne fine particulate matter PM2.5 as one of composite core pollutants of air pollution is concerned and NO as one of the main components of water-soluble ions has an important impact on precipitation and human health, so searching a method of rapid and reliable detection is an important work. According to advantages of the Fourier transform infrared spectroscopy technology, the infrared spectrum of NO3- in NH4NO3 was compared with PM2.

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In the present paper, the infrared spectrum of aerosol and NH4 NO3 was analysed and compared, and the result showed that the infrared spectral features of aerosol are consistent with that of NH4 NO3. The absorption coefficient alpha and the mass absorption cross section kappa of NO3- was calculated by the transmissivity of NO3- in NH4 NO3 according to Beer-Lambert law. Then the imaginary part of the complex refractive index was calculated through alpha.

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The authors measured IR transmission spectra of two different concentrations of Bacillus subtilis spores by using Fourier transform infrared spectroscopy (FTIR) technology. The mass extinction cross section k of Bacillus subtilis spores was calculated according to Lambert-Beer law and the imaginary part n(i) of the complex refractive index was also calculated through k. The real part n(r) of the complex refractive index was derived from the KK (Kramers-Kronig) relationship and the experimental results were also analyzed and discussed with the study of measurement and analysis method of the complex refractive index on Bacillus subtilis spores, it is of great significance to further research the absorption and scattering characteristics, and to broaden the measurement and remote sensing technology method of the biological aerosols.

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Passive remote sensing by Fourier-transform infrared (FTIR) spectrometry allows detection of air pollution. However, for the localization of a leak and a complete assessment of the situation in the case of the release of a hazardous cloud, information about the position and the distribution of a cloud is essential. Therefore, an imaging passive remote sensing system comprising an interferometer, a data acquisition and processing software, scan system, a video system, and a personal computer has been developed.

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An ozone monitoring system was developed by the method of open path Fourier transform infrared (OP-FTIR) spectrometry based on our FTIR spectrometer. In order to improve measurement precision and detection limit, the quantitative analysis was completed to get ozone concentration by combining synthetic background spectrum method which uses information from HITRAN database and instrumental line shape, and nonlinear least squares (NLLSQ) method. The measurement methods for system detection limit were discussed and the result is 1.

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The stratosphere ozone plays the protective action role for human and the ground-level ozone is harmful to human health. Monitoring ozone with different ways and methods took an active part in understanding distribution and transformation of ozone, which was useful to controlling pollution emission. Spectra were got by multi-reflected white cell Fourier transform infrared (FTIR) spectrometer, inversed with nonlinear least squares (NLLSQ) method and then the concentrations of ozone were got exactly.

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The spectral line widths of theory and experiment are analyzed with different temperatures; the line strengths under room temperature in HITRAN database are corrected to measured temperature, and then synthetic spectra are calculated. With the nonlinear least squares fit between measured spectra and calibration spectra, standard gas concentrations of CO at different temperatures are obtained. The inversion concentration error of this algorithm at room temperature is less than 5% with high precision.

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In the present paper, a new method is introduced for real-time monitoring polluted gas emission flux of chemical plant, which is called FTIR based on the solar occultation flux technique (SOF-FTIR). The model to obtain background spectrum, measured spectrum and atmospheric penetration rate surrounding polluted gas under complicated conditions is also proposed. Continuous measurements were preformed at a closed loop surrounding the contaminated areas that need to be mornitored to obtain measured spectrum, and finally column concentration of polluted gas was retrieved by using the nonlinear least squares fitting algorithm (NLLS).

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Article Synopsis
  • - The authors conducted an analysis of NH3 volatilization from various fertilizers using FTIR spectra measurement and retrieved concentration data through NLLS arithmetic with the HITRAN database.
  • - They compared the NH3 concentrations from different fertilizers and explored the reasons for variations in these concentrations.
  • - The study highlighted the advantages of using FTIR spectra for measuring NH3, citing benefits like simplicity, high efficiency, real-time capability, and continuous measurement, making it suitable for field analysis.
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The present paper introduced a FTIR scanning imaging system. This system is based on the combination of a FTIR spectrometer and a scanning mirror. So it has the advantage of FTIR spectrometer: non-contact, real-time, celerity, nicety and high sensitivity.

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Article Synopsis
  • The FTIR (Fourier-transform infrared spectroscopy) technique has rapidly advanced since the 1980s and is now crucial in various fields, emphasizing the importance of accurate manipulation and calibration of the FTIR spectrometer.
  • Accurate calibration is necessary to obtain reliable spectral data, as the instrument's response varies across different wavebands and non-calibrated spectra can be erratic.
  • The paper discusses two calibration methods: linear calibration for linear detectors and non-linear multiple point calibration for non-linear detectors, reporting that the non-linear calibration showed an impressive accuracy of about 0.2% relative to standard blackbody spectra.
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FTIR spectrometer detectors have different instrument response function in different wave band. In application, no matter absolute or relative intensity of spectrum the authors use, the authors should calibrate the instrument with standard blackbody to find the instrument response function. In the present paper, the authors study the instrument response function of detectors (InSb detector and MCT detector) in Canada MOMAN MR154 FTIR spectrometer.

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Water vapor absorption, which exists in mid-infrared region, is an interferential element for infrared spectra analysis. A new method, which can be used to eliminate the water vapor interference in FTIR measurement, is presented. To calculate the high resolution absorbance of water vapor, a fast line by line method which computed with the HITRAN database (eg.

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The present paper analyzed the molecular spectra theory detailedly and summarized the factors affecting the structure and intensity-distribution of molecular rotation-vibration spectra. The authors knew that every spectral line's relative intensity is only related to external temperature. According to this conclusion.

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Article Synopsis
  • The greenhouse effect, primarily driven by human activities, is linked to rising levels of greenhouse gases like CO2 and CH4, raising global concern for environmental monitoring.
  • Researchers employed a Fourier transform infrared spectrometer to track CO2 and CH4 concentrations at a designated site in Beijing, utilizing a long open path for air sampling over one month.
  • The study provided detailed absorption spectra and employed advanced statistical methods to analyze gas levels, reporting data with a five-minute resolution for the dates of September 4-10, 2005.
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In active infrared remote sensing measurements, the infrared absorption caused by the presence of trace gases in atmosphere is related to the transmittance spectra in different infrared wave band. In many cases, transmittance spectra play an important role in spectsal quantitative analysis. Thus, the selection of wave band to be optimized for the measured and simulated transmittance spectra is the key in quantitative analysis.

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Methane (CH4) is an important greenhouse gas and a key molecule in tropospheric photochemistry, some more potent than CO2. The remote-sensing experiments of CH4 were carried out in the fall of 2 000 in Beijng. The 6-day records of the atmospheric CH4 concentrations were examined by means of a time-series analysis using a fast Fourier transform with a low-pass filter to elucidate the seasonal cycles and the long-term trends.

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In the remote-sensing experiments of CO2 in Beijng, the authors found that the higher concentration of CO2 in autumn is caused by the CO2 emission by the traffic sector during the day time. During the day time, the concentratration of CO2 is comparatively lower because of the photochemistry and the transportation of troposphere. And the concentration of CO2 is about 410 microg x mL(-1).

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