  Defects arise when nematic liquid crystals are under topological constraints
at the boundary. Recently the study of defects has drawn a lot of attention. In
this paper, we investigate the relationship between two-dimensional defects and
three-dimensional defects within nematic liquid crystals confined in a shell
under the Landau-de Gennes model. We use a highly accurate spectral method to
numerically solve the Landau- de Gennes model to get the detailed static
structures of defects. Interestingly, the solution is radial-invariant when the
thickness of the shell is sufficiently small. As the shell thickness increase,
the solution undergo symmetry break to reconfigure the disclination lines. We
study this three-dimensional reconfiguration of disclination lines in detail
under different boundary conditions. We also discuss the topological charge of
defects in two- and three-dimensional spaces within the tensor model.
