The topological quantization and bifurcation of the topological linear   defects
  In the light of $\phi$-mapping method and topological current theory, the topological structure and the topological quantization of topological linear defects are obtained under the condition that the Jacobian $J(\phi/v) \neq 0$. When $J(\phi/v) = 0$, it is shown that there exist the crucial case of branch process. Based on the implicit function theorem and the Taylor expansion, the origin and bifurcation of the linear defects are detailed in the neighborhoods of the limit points and bifurcation points of $\phi$-mapping, respectively. 
Yishi Duan, Ying Jiang, Guohong Yang