The method of simultaneous determination of the temperature and partial pressures of gaseous mixture components on the basis of measured spectral characteristics is considered. The transmittances of a gaseous mixture consisting of H2O, CO2, CO and NO gases, which were simulated by the line-by-line method using the HITEMP2010 database, are considered. It is shown that the potential accuracy of the method depends only on the agreement between the theoretical and experimental spectra of gases. The influence of the error in the transmittance on the errors in finding the temperature and partial pressures of gases is discussed.
The criteria for choosing optimal wavelengths for remote sensing of gaseous media are considered on an example of CO2 laser. The influence of various factors on the experimental and theoretical values of the spectral characteristics of the medium is estimated.
In this work the temperature dependences of the integrated intensities of the absorption bands of the asymmetric top molecules – H2O, H2S, SO2, and NO2 were analyzed. A different view of the temperature dependences was shown for cold bands including fundamental ones. For calculating the integrated intensities, the spectral line intensities were used from the known and author’s spectroscopic databases. The reasons are discussed which lead to increasing and decreasing the integrated intensities at high temperatures (T>300 K).
The method of approximation polynomials for simultaneous determination of the temperature and concentration of a heated gas from its spectral characteristics is considered. The accuracy of finding the experimental values of the thermodynamic parameters was increased by using an arbitrary number (≥ 2) of spectral centers and taking into account the measurement error of the transmission function. Approbation of the improved technique was carried out using the most accurate measurements of the transmission function of carbon dioxide in the temperature range 500-1770 K and the partial pressure ρCO2 = 0.17-1 atm.
In this work the contributions from the hot bands in the total absorption of H2S, SO2, and NO2 were calculated at temperatures of 300 – 1000 K. The high-temperature spectroscopic databases of the authors were applied for calculating the sum absorptions. The reasons of the different contributions from the cold and hot bands in the absorption spectra of the considered gases are discussed.
A numerical model of a multicomponent gas-aerosol medium designed for studying the transmission function in the visual and IR ranges has been proposed. Taking into account the molecular absorption by the gas component and also the light scattering and absorption by the aerosol, the radiation extinction is determined. To calculate the optical characteristics of a dispersed component, the Mie theory is applied. Methane is selected as the main gas component of the medium. The separate and combined contributions of molecular absorption and aerosol extinction to the transmission of optical radiation by a gas-aerosol medium are analyzed.
The CO2 transmission function was calculated and compared with the experimental data in the spectral range of 450- 7600 cm-1. The spectral ranges suitable for a determination of temperature and concentration of CO2 were determined. The influence of polynomial degrees on errors of approximating the transmission function and the influence of a number of spectral regions on errors of determining the temperature and partial pressure were analyzed.
The analysis of the calculation results of extinction coefficient, scattering coefficient, and absorption coefficient of aerosol, as well as transmission function under the joint and separate impact of components of mixture containing trioxide dialuminum was carried out. The spectral features of the optical characteristics of the medium at various parameters of particle size distribution function were illustrated.
A validation of spectral line parameters of hydrogen sulfide (H232S) from the spectroscopic databases HITRAN2012 and GEISA2009 was carried out. For this aim, the absorption coefficient of H232S calculated by a line-by-line method is compared to experimental data from the Pacific Northwest National Laboratory. A list of the spectral line parameters of H232S of the authors is also used for the comparison. The line positions and intensities from the author’s line list were calculated by the effective operator method. The parameters of the effective dipole moment of the ν2 band of H232S were determined. Finally, the HITRAN2012 and GEISA2009 data differ from the experimental ones in the ν2 band and there are errors in line positions of the first and second triad bands from HITRAN2012.
A complete set of dipole moment function parameters of sulfur dioxide (32S16O2) were determined up to the second order inclusively. For determining the parameters, the experimental vibrational transition moments of the ν1, ν3, ν1+ν3, and 2ν3 bands were used from literature. The vibrational transition moments of the ν2, 2ν2, ν1+ν2, ν2+ν3, and 2ν1 bands with uninvestigated experimentally line intensities were obtained in this work on the basis of the ab initio line intensities of 32S16O2. The results of this work were validated by a comparison of the simulated absorption coefficients with the measured data taken from the Pacific Northwest National Laboratory.
A description of an Internet accessible software «Optics and spectroscopy of gas-aerosol media» is represented. The new software is focused on research in the field of direct and inverse problems of optics and spectroscopy of gas-aerosol media.
The modelled absorption coefficients of 14N16O2 are performed in the range of pure rotational and vibrational-rotational transitions at T = 300 K and T = 1000 K temperatures. The calculations were carried out on the basis of the developed by authors high-temperature database of NO2 spectral line parameters and database HITRAN2012. The dipole moment function parameters of NO2 up to the second order inclusive were also determined.
The intensities of water vapor in the range of pure rotational transitions were calculated up to high quantum numbers (Jmax ~ 30 and Ka max ~ 25). The diagonalization of the effective rotational Hamiltonian, approximated by Pade-Borel method, is applied to obtain the eigenvectors. The centrifugal distortion perturbations in line intensities were taken into account by the traditional equations for matrix elements of the transformed dipole moment, including eight parameters, and previously developed by authors Pade approximant. Moreover, to conduct the calculations, the rotational wavefunctions of the symmetric rotor molecule were applied. The results were compared with the known theoretical data.
Calculated absorption spectra of the mixture of gases (H2O, CO, CO2, NO, NO2, and SO2) and aerosol (soot and Al2O3), contained in the exhausts of aircraft and rocket engines are demonstrated. Based on the model of gas-aerosol medium, a numerical study of the spectral dependence of the absorptance for different ratios of gas and aerosol components was carried out. The influence of microphysical and optical properties of the components of the mixture on the spectral features of absorption of gas-aerosol medium was established.
In this work, a numerical study of the transmission function, extinction coefficient, scattering coefficient, and absorption coefficient of the aerosol generated by the jet engine emissions was performed. Analyzing the calculation results of the IR optical characteristics of anthropogenic emissions containing the dialuminum trioxide was carried out. The spectral features of the optical characteristics of the medium caused by the average size, concentration and complex refractive index of the particles were illustrated.
Review of the authors' works devoted to research of properties of high-temperature gas mixtures and advancement of methods of a remote diagnosis of their optical and physical characteristics is presented. Results of the formation of the informational resource on mathematical, spectroscopic, software and hardware support of passive and active remote sensing techniques of gas-aerosol media are discussed.
A numerical study of the gas-aerosol transmission function in IR range for various optical and microphysical parameters has been performed. Limit values of the aerosol particle concentration and effective radius that allow us to estimate a contribution of the gas and aerosol components to the radiation extinction have been determined.
A semiempirical model in the form of Pade approximants, describing vibrational-rotational (VR) interactions in intensities of VR-lines of v2 water vapor (H2O) band, was developed. The corresponding to the C2v molecular symmetry group matrix elements, involved in the expansion of the transformed dipole moment, was applied to the derivation. The treatment of experimental intensities of v2 H2O band for transitions with ΔK = ±1 and ΔK = ±3 by means of obtained model results in decreasing the root mean square deviation (RMS) about two times (2.82 % instead of 6.20 %) in comparison to the traditional scheme.
Passive methods of remote analysis of gases of industrial enterprises and aircraft engines and gases ejected in
eruptions of volcanoes, in fires, and in other processes disturbing the atmosphere are now of limited utility because of the
lack of well-developed mathematical techniques for solving the inverse problems of gas analysis. The current status of
research does not offer reliable tools for finding spatial distributions of thermodynamic parameters of a gas medium from
passive remote measurements. Possible significant concentrations and temperatures, typical, for example, of forest fire, lead
to an optically dense medium for which exponential relations, such as the Bouguer law, are not informative. This calls for the
the new ways for processing optical measurements, some of them are suggested in the paper.
The current status of research does not offer reliable tools for finding spatial distribution of thermodynamic parameters
of the gas medium from remote measurements. At the same time the direct task to determine the spectral gas characteristics
requires additional development too. In the given paper the consideration for gaseous carbon and nitrogen oxides and analysis of
an error arising at application of homogeneous layer approximation to gas volume with essential gradients of temperatures and
concentration will be carried out. The account of transmissivity and emissivity of gases was made in the spectral region of the
fundamental bands from 1400 up to 24OOcm-1 for temperatures 300-3000K. The most effective possibility to analyze the
reliability of calculated spectral line parameter databases fully is the Planck-mean absorption coefficient and the comparison with
the other authors calculation results was fulfilled.
The report is devoted to the research of IR spectrum of high temperature (T < 3000 K) and thermodynamic inhomogeneous heat water vapor. The physical models of the description factors of absorption and emissivity within the framework of direct accounts line by line are discussed. The main attention is given to the form of the spectral lines parameters databases of water vapor based on generating information system HOTGAS-H20. Assuming that the radiation diffusion and local thermodynamic balance are fulfilled inside a layer, the emissivity calculations for various path conditions of concentration and temperatures 300-3000 K are designed. Thus, stratified environment formed by an user was simulated by layers of various thickness. Approximations of absorption coefficients simplifying considerably calculations are proposed. The estimation of the nonselective absorption of water vapor in the range 8-12 microns for temperatures I 500-3000 K are given for the first time.
The new calculation approach of water vapor rotational energy levels using symmetric top model for Ka>=J/2>>1 has proposed. The rotational spectroscopic parameters of the Pade-approximation for ground vibrational state of H2O molecule in the frame of this model was obtained. The absorption coefficient of water vapor in a spectral range 850-920 cm-1 was calculated for 1000 - 10000 K temperatures.
Investigation of gas media spectroscopy at high temperature is accompanied by large and complex data amount. In order to manage these data one should use specialized information systems able to execute formal stale operations with friendly interface. In the present paper we discuss the problems of development of an integral distributed information system using up-to-date object oriented technologies and technologies for distributed systems based on CORBA 2.0 (Common Object Request Broker Architecture). On the basis of modern information technologies we have developed HOTGAS and SMOLA software. Both can be run under Windows operation system. HOTGAS is intended for calculation of spectral line parameters (SLP) and absorption coefficients for CO, CO2 and H2O in 250 - 3000 K temperature range. SMOLA is intended for accumulation, systematization and use of published SLP data for different molecules. It also has a graphic interface and possesses the advantages of other Windows software. To provide comprehensive informational support and to execute all the diversity of tasks in the sphere of rovibrational spectroscopy of gas media we offer a project for integral distributed informational system design.
The information system HOTGAS 2.0 for calculation of rovibrational spectral line parameters (centers, intensities, half-widths, energies of low states) of CO, CO2 and H2O in 0 - 10000 cm-1 spectral range and in 200 - 3000 K temperature range is described. The information system HOTGAS 2.0 developed for Windows 95,98,NT has a friendly user interface with textual and graphical information performance, which allows for using graphics and tables in other Windows applications, such as Word, Excel, etc. The HOTGAS 2.0 makes calculations of the absorption coefficient for single or mixed gases available.
The schemes of use of two various methods in a problem of restoration of altitude structures of concentration of gases from results of satellite sounding of atmosphere are submitted. Computing experiment on both methods on an example ozone is spent. Results having acceptable accuracy are received. Lacks of both methods are specified.
New logical and conceptual structure for the Atmospheric Molecular Spectroscopy Information Retrieval System (AMSIRS `ATLAS') has been developed by extending molecules types and thermodynamical conditions and adapting it to a personal computer (IBM PC AT). Management subsystem AMSIRS `ATLAS' links individual blocks, which realize their own algorithms and the user's interface. Management subsystem has been integrated using a mutual working menu.
In this work the atmospheric transmission spectra T equals f((lambda) ) were determined experimentally by the balloon experiments in the region of 8.0 - 12 micrometers with resolution about 5 cm-1. The balloon-borne spectrometers have three optical channels. Two channels are used for simultaneous registration of two solar spectra, the third one serves for the uninterrupted registration of the solar intensity during all the time of the flight in the two narrow spectral regions (0.02 micrometers ) obtained with the use of the interference filters at (lambda) equals 0.5 micrometers or (lambda) equals 0.8 micrometers . All the measurements were performed during lifting the apparatus at the positive sun heights hradii > 0 and during gliding at altitude about 30 km firstly at the positive and then at the negative solar heights.
Development of methods for calculating spectral characteristics of high temperature gases, which are products of a fuel combustion and components of industrial emissions, is necessary for creation of instrumentation for measuring of gas concentrations.
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