Optimization method for Coulomb potential by Natoli was improved,in which simple polynomial basis functions are used to fit slowly varying long-rang part of potential,and limited conditions are set to enhance consistency.Without increasing computational complexities,an optimal potential with lower mean squared difference is obtained.Cutoff criterion in real and reciprocal space determining optimal breakup of exact potential is suggested k_cr_c ≥ 15.New potential was tested on dense liquid hydrogen which shows lower pressure and energy than Natoli and Ewald potentials.

Delaunay background grid,edge spring grid and linear spring grid are used to study computational domain grid movement on non-structural grid and structure grid for non-streamlined bridge section.It shows that the methods are effective as grid deformation within a normal vibration amplitude of the bridge section.Delaunay grid background method consumes the least time and the linear spring grid method obtains the highest quality.It also shows that with large amplitudes,structural grid is invalid easily and linear spring grid method ensures effectively.

For a Fibonacci chain constructed recursively with S_m+1={S_m|S_m-1}, in a tight-binding model of single electron, we investigate numerically density of electronic states and electronic energy band structure with negative eigenvalue theory and three diagonally symmetric matrixes. Trifurcating structure of energy band of the system is demonstrated. With renormalization-group method and scattering theory, we study localization length and transmission coefficients of electronic states in a chain. At particular eigen-energies, extend states with localization lengths greater than size of the system are found and transmission coefficient is equal nearly to 1. At most eigen-energies, corresponding electronic states are localized states due to short localization length. In addition, relations between transmission coefficients and parameters of Fibonacci chain are qualitatively investigated.

Based on the MT(Multipole Theory),a new method is presented for calculating the electrical conductance of cables with complicated cross-section.By analyzing two examples, it is proven that the calculating accuracy of the MT is much better than that of the BEM(Boundary Element Method).

FDTD is a numerical method to seek the solution of Maxwell equations by marching in tihme domain, which can be used to analyze the interactions between electromagnetic fields and complicated objects. The fundamentals of FDTD are discussed in this paper, and some useful skills introduced. In particular, complex field components are used in time-harmonic case in order to obtain smooth output for phase. Finally, some examples are provided.