Unfolding algorithms for neutron depth profiling:probability iteration, SVD solving least square, linear regularization(LR) and constrained linear reqularization(CLR) are studied. All algorithms are applied for both under-determined and over-determined equations, and results are compared and discussed. Due to iterative processes, probability iteration and CLR could not work well in the case that sources intensities change sharply. LR is unstable as unfolding range is chosen arbitrarily, which can be constrained by CLR. A practical spectrum of NDP experiment is unfolded by algorithms. LR could not restrain stochastic errors caused by statistical fluctuation, while other algorithms show good unfolding results and agree well with references.

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.

A coupling method is developed to describe field-structure interaction.Eulerian multi-material hydrodynamic code is used to simulate fluid field.Lagrangian hydrodynamic finite element code is used to calculate response of structures.Coupling technology is made to merge these two codes.Technology to speed calculation and to avoid mismatch of fluid structure meshs and structure meshs are given.Dynamic response and shock wave propagation within an explosion containment vessel are simulated.Fluid-structure coupling algorithm is used for analyzing coupling of explosion field and structures.It indicates that the method has the ability of simulating fluidstructures interation.

First principle method is used to study the electronic properties of doped nanotubes. Compared with the pure carbon nanotube, the carbon nanotube doped with one Fluorine atom can exist stably and has better properties in field emission. This material design is on atomic level.