Most of the traditional infrared remote sensing systems are single-band imaging with wide spectral range, which cannot adapt to the variability of background and target characteristics in point target detection. The full-link model of point target detection by space-based infrared sensor is constructed, the target, background, atmosphere, sensor spectral response, space response, radiation response, noise characteristics and other factors are comprehensively considered. A band optimization method based on detection signal to noise ratio is proposed. With the cloud and sea background as the typical background, three narrow bands are selected in the short-wave, medium-wave and long-wave ranges, respectively.
Improved Grouping strategies for spectral subintervals of multi-scale multi-group full-spectrum k-distribution models have been done by considering the influences of both temperature and participating species mole ratio variations on correlated-k characteristics of the spectra of gas mixtures. Finally, evaluations are presented on the calculation of thermal images of supersonic hot jets exhausted from a Chevron ejecting nozzle under a 3–5-micron wave band.
For the ground combustion process of MTV grain, the flow field distribution of combustion products was simulated based on the set combustion boundary conditions. The combustion product is a two-phase flow of particles and gases, which is accompanied by the chemical reaction of C particles with oxygen to produce CO2 gas. Based on the results of the flow field, the infrared radiation spectra at different positions above the grain are calculated. The calculated results show that the radiation contribution of particles and gases in the flow field is close, and the radiation spectrum of the combustion product flow field is formed together. The radiation above the grain decays rapidly with the increase of distance.
Hypersonic body moving in the atmosphere will suffer high temperature reacting flows which will emit complex radiation. Theoretical calculation was taken in this paper for a hypersonic non-ablative sphere. Hypersonic flow around the sphere was simulated using 9 species chemical kinetic and two temperature thermal non-equilibrium model. Based on this simulated flow field, the LOS method is used to solve radiative transfer and line-by-line model is used to calculate the spectrum from molecular and atoms in mid-infrared. The spectra from different components have been analyzed one by one. The calculation founds out that atom N and O diatomic molecule NO and bremsstrahlung will be important radiation source in this pure air hypersonic flow field. The radiation from hypersonic flow field has been analyzed in both high pressure environment and low pressure environment.
The spectra have been calculated with Line by Line method for high-temperature CO2 and atmosphere. The characteristic of the wing of atmospheric 4.3μm absorption band has been analyzed. The variation of transmittance from different altitudes to space in 2370 to 2390cm-1 was calculated and analyzed. The radiations of high-temperature CO2 located in different altitudes in the same wave range were compared. According to the variation of atmosphere and the spectral characteristic of hot CO2, the way for choosing band of detection was discussed.
This article studies the near sea surface atmosphere visibility and aerosol scattering asymmetry factor with observed weather data. Based on muti-modal log normal distribution model, Mie theory and SCE-UA method, near sea surface atmosphere aerosol parameters, such as distribution parameters and relative refractive index, are inversed. A discussion about the relationship between the inversed parameters and weather data is present.
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