| Along with the further development of science and technology level, in many aspects of the production of the national science and technology, such as petrochemical industry, biological pharmacy, pollution prevention, infrared detection, and satellite remote sensing and so on, the research of participatory media radiation property is increasingly close. The radiation properties of participatory media, such as particle size distribution, the incident laser optical constants, scattering coefficient and absorption coefficient and so on, all have the direct impact on the basic process of the radiative transfer. Both the gas phase, liquid phase and solid phase, particulate matter particles are widely distributed in various kinds of participatory media. The existence of atmospheric aerosol particles has significant influence on climate change and the solar radiation in atmosphere. And the product particle size and particles distribution of industrial production are directly related to quality and performance of the product. The size of the granular materials used on modern industry has reached nanometer level. The ability of using the ultrafine particle materials directly reflects the high-tech development level and the construction of national defense scientific research strength. The optical constants is one of the important physical parameters of participatory media, it is necessary for solving participatory media radiative transfer problems, and has special important meaning to studying infrared stealth of aircraft and detecting infrared target of military aircraft.At present, There are a lot of means of the inversion of particle system property for participatory media, and the main methods used for the property of participatory media particles are extinction method and light scattering method. The inversion methods of optical constants of particle system of participatory media are mainly the reflection method, scattering method, projective method with the K-K relation. And solution of the scattering coefficient and absorption coefficient can use positive solution with known optical constants and so on, and the inverse problem can also do that. In this paper, the transmission-reflection combined method is used for participatory media inversion of particle size distribution and the optical constant and the use of this method avoids solving K-K relation. But it is based on the premise of the spherical particles, it itself has the relative limitation.This paper first introduces the background, the significance, the development course and the practical condition of physical properties study of the participatory media. Then, on the base of introducing the BP neural network algorithm and particle swarm optimization algorithm(PSO) theory, puts forward the corresponding improvement model to the problem of low precision in local area and the bad population diversity in optimization process. And multi-strategy improved PSO algorithm is used to optimize threshold coefficient and the weight coefficient of the BP neural network, and establishes a BP neural network model of multi-strategy improved particle swarm optimization(MPOPSO-BP). Through the validation of test functions, the accuracy and convergence rate the algorithm are increased with the improvement of multi-strategy improved particle swarm.Finally, in the paper, the BP neural network model of multi-strategy improved particle swarm optimization is used for the inversion of radiation physical properties of participatory media. And calculate the particle size distribution, scattering coefficient, absorption coefficient and optical constant of participatory media. And put forward a kind of joint inversion method of particle size distribution and the optical constant. |
