Calculation of the Radiating Characteristics of a Thermodynamically Nonuniform Gas Medium

Passive methods of remote analysis of waste gases of industrial enterprises and aircrafts engines and gases ejected in eruptions of volcanos, 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. However, the advantage of these methods is obvious, since the equipment is limited to a receiving device and the gas medium serves as a radiator. At the same time, in modern techniques, the interpretation of measurements of emissivities of gases is performed using a phenomenological approach such that experimental data on radiation characteristics of various objects are approximated by simple polynomial relations whose coefficients are determined by minimization methods. This approach does not allow one to investigate the mechanism of the processes occurring in a radiating medium and gives no way of solving the inverse problem of monitoring the composition and thermodynamic parameters of a medium which disturbs the atmosphere by thermal effects. In elaborating theoretical methods of gas analysis, the elaboration of the direct problem of calculation of radiating characteristics of gases is of importance, since it is not clear how the emissivity of a gas medium depends on its thermodynamic parameters. This paper is devoted to the above problem. Here, the error is estimated that arises in modeling a nonuniform gas medium with an actual temperature distribution, which linearly depends on coordinate, by a uniform gas layer. It is shown that the difference between the radiation intensities calculated for uniform and nonuniform media can be significant in the practically important case where the recording device is in a zone of normal temperatures. This implies that the error of reconstruction of the spectroscopic and molecular parameters of gaseous compounds from high-temperature measurements of the radiating and absorbing characteristics should take into account the thermodynamic nonuniformity of the medium.     

Rate of convergence bound of difference schemes for quasilinear elliptical equations with solutions inW 2 1

We consider a mixed boundary-value problem for a quasilinear elliptical equation of second order in the rectangle with a generalized solution in W ₁ ² (). Exact difference scheme operators are applied to construct a first-order accurate difference scheme in the L₂ grid norm.Kiev Technological Institute of Light Industry. Translated from Vychislitel'naya i Prikladnaya Matematika, No. 75, pp. 50–55, 1991.     

Transmission of Optical Radiation by a Polydisperse Ice Cloud

Russian Physics Journal - Results of calculation of the transmission function for ensembles of ice crystals typical of crystal clouds are presented as functions of the wave numbers. Considering...     

Application of the Padé approximations to calculation of rotational energies of a triatomic linear molecule

A possibility of applying the Padé approximations to calculation of rotational-level energies of degenerate vibrational states is studied for linear molecules with various quantum numbers of the vibrational angular momentum 1. The calculations of rotational energy levels for the CO ₂ molecule show that the Padé form has a better predictability as compared to a power series. Spectroscopic constants of the Padé approximations for the vibrational states (04⁰0, 04²0, 04⁴0), (14⁰0, 14²0, 14⁴0), (15¹0, 15³0, 15⁵0), and (06⁰0, 06²0, 06⁴0, 06⁶0) for the CO ₂ molecule are determined. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 54–57, September, 2006.     

Approximation of Inverse Models for Temperature-Concentration Dependences of the Transmission Function of a Single-Component Homogeneous Gas Medium by Artificial Neural Networks

Russian Physics Journal - The problem of application of artificial neural networks for approximation of inverse models of temperature-concentration dependences of the transmission function of a...     

Determination of spatial distribution of gas concentration in an inhomogeneous gas volume from integral characteristics of attenuation of laser radiation

The problem of finding a one-dimensional distribution of the concentration of an individual component in a thermodynamically inhomogeneous gas mixture is considered. Use is made of a polynomial approximation of the absorption coefficient along the path as a function of the spatial coordinate. The spatial distribution of the gas concentration is regarded as a probability density function. A computational scheme is proposed for quantities analogous to statistical moments. A numerical experiment has been performed using estimates of these quantities for vertical ozone and water vapor distributions in the atmosphere as examples. This approach is deemed appropriate for extended paths, such as the Earth—space path, where traditional methods prove to be ineffective. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 44–49, June, 1999.     

Electron and hole spectra in complex spherical semiconductors of nano-scale heterosystems

The electron and hole spectra in the spherical potential well created by a double spherical heterostructure are investigated. Two mutually inverse nanoheterosystems are considered: CdS/HgS/H₂O and HgS/CdS/H₂O. The dependence of the energy levels on the film thickness is calculated for various values of the principal and orbital quantum numbers. In the spectra obtained, the energy levels are pushed apart. Chernovtsy State University, Chernovtsy. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 41, No. 12, pp. 58–65, December, 1998.