physical equation

Stefan problem is free boundary condition of physical equation in thermal transfer when the boundary change.

斯蒂芬问题是研究边界变化时导热规律的的物理方程的自由边界条件.

A mathematic-physical equation that describes the natural neutron radiation field is theoretically established, in which the natural neutron flux is considered for the fast neutron group ( E-n> 0.1MeV) and slow-thermal neutron group according to neutron energy.

将天然中子按能量分为快中子组（En>0.1MeV）与慢热中子组，建立了地-空界面上天然快中子流与慢热中子流粒子注量率随空间分布的数理方程。

Consequently an analytical equation in terms of porosity, strain and spherical stress tensor is put forward by virtue of logarithmic strain, the plastic condition and the physical equation of pore mechanics.

为此，本文利用对数应变和孔隙力学的塑性条件及物理方程，建立了孔隙率与变形和应力球张量的解析关系式，进而得到了疏松缺陷压实的修复条件。