And the singularity of quadratic isoparametric elements with the mid-side node near the crack tip at the quarter point was investigated. It was proved here that along the diagonal of such a square element the displacement expressions still contain r~ ( 1/ 2) term. 并且对具有四分之一边中结点的二次等参元的奇异性问题作了研究,证明了对于正方形的这种单元,沿对角线方向的位移仍含有r~(1/2)项。
Thirdly we introduce the superlattice model with alternating site energies which is more complicated than the simple tight-binding model, and moreover we explore the influence of the alternating diagonal term in Hamiltonian on the quasi-energy bands and dynamics. 接着引入更为复杂的格点能交替变化的超晶格模型,并在此基础上考察了Hamiltonian中交替变化的对角项对准能谱与动力学的影响。