Based on a fact that impedance matrix in the method of moments(MoM) is independent of incident angles,a compressive sensing(CS) technique is introduced in constructing an incident source,in which much information about incident angle is included.Under the incident source,measurement of induced currents can be obtained with MoM.With orthogonal matching pursuit(OMP) technique,induced currents are reconstructed with few measurements.Compared with conventional MoM,high accuracy numerical results are obtained while computational time is reduced to one third.Computational complexity of wide angle electromagnetic scattering is reduced greatly.

Euler-Hamilton equations are provided using Hamiltonian function of Maxwell's equations.High order symplectic schemes of three-dimensional time-domain Maxwell's equations are constructed with symplectic integrator technique combined with high order staggered difference.The method is used to analyzing stability and numerical dispersion of high order time-domain methods and symplectic schemes with matrix analysis and tensor product.It confirms accuracy of the scheme and super ability compared with other time-domain methods.

Multi-step high-order finite difference schemes for infinite dimensional Hamiltonian systems with split operators are proposed to solve time domain Maxwell's equations. Maxwell's equations are discretized in time direction and in spatial direction with different order of sympleetie schemes and fourth-order finite difference approximations, respectively. Stability analysis and numerical results are presented. A five-stage fourth-order multi-step high-order finite difference scheme proves accurate and efficient, and applicable to long time simulations.

A multi-dimensional particle-in-cell code KLAP is introduced. Field ionization, impact ionization and two body collision are considered in a one-dimensional code. Moving window technology is used in a three-dimensional code to study laser wakefield acceleration in GeV region. Terahertz radiation, laser propagation in neutral gas medium, surface electron acceleration as well as GeV electron generation in laser wakefield acceleration are studied.

Transitions and oscillator strength for highly ionized CoⅠ-like Rh¹⁸⁺ ions 3p⁶3d⁹-3p⁵3d¹⁰,3p⁶3d⁹-3p⁶3d⁸4p are calculated by using Cowan's multiconfiguration self-consistent field method together with the fitting formula proposed here.The calculations are in agreement with observations.

Based on a reasonable fitting formula of highly ionized atomic energy level,3d⁹-3p⁵3d¹⁰,3d⁹-3d⁸4 transitions wavelengths and HFR theoretical osciallator strengths for Co like 49≤Z≤53 ions are calculated.

The energy level、wavelength and Oscllatar strength for Highly ionized NiI-like ions 3p⁶3d⁹,3p⁵3d¹⁰ and 3p⁶3d⁸4p configurations are calculated by using Cowan's multiconfiguration selfconsistent field method together with the fitting formula proposed here.

Analytical solutions of the freezing of phase change material (PCM) in annular space are presented. Firstly, approximate integral method and numerical simulation are used to analyze the heat transfer process during the freezing of the PCM in annular space with internal boundary cooled and external boundary insulated.Secondly, a comparison is made between the results obtained by approximate integaral method and the numerical solution. Then, the effects of all kinds of parameters on the freezing process are discussed. Finally, two important conclusions are summarized:1.when the ratio of the inside diameter to the outside one of the PCM is not less than 0.6, we can assume a quadratic temperature distribution in PCM instead of a log arithmic one so as to cut down the efforts used in solving process, and the error will not exceed 1.5%;2. approximate integral method is not apropriate for solving those solid-liquid phase change problems which possess a low Stefan number.

In this paper,the energy level-wavelength and Oscllatar strength for Highly ionized NiⅠ-like ions 3d⁹4s,3d⁹4p and 3d⁹4d configurations are calculated by using multiconfiguration selfconsistent field method together with the fitting formula proposed here. The calculations have a good agreement with observations.