When PO(Physical Optics)method is used to calculate the scattered field of electrically large objects,the double reflection between two objects should be considered independently.

Those main factors are discussed,they include: the initial velocity can enlarge the changed wavelength;the bound energy could reduce the changed wavelength;the double Compton scattering and the Compton scattering which produces two photons change the changed wavelength,and the changed wavelength is uncertain,complex and continuous.

After compared with the experiments,they have concluded that the double Compton scattering and the Compton scattering producing two photons can occurr possibly in Compton scattering.

We propose a simple hadronic transport model for investigating the K+/π+ratio in relativistic nucleus-nucleus collisions and point out that the thermal motion of baryons and multiple rescattering effect play an important role in the enhancement of K+/π+ ratio.

Characteristics of gain, amplified spontaneous Raman scattering and double Rayleigh backscattering in a B-DFRA with point defect are studied separately, and the comprehensive effect of the point defect is discussed by equivalent receiver sensitivity.