...crostructures with penalization，SIMP）［13-141和材料属性的有理近似模型（rational approximation of material properties，RAMP），两种模型通过增大惩罚因子数值对中间密度值进行惩罚，使之向0．1状态靠近，减少了中间材料的出现。
The twomethodsofmodelsimplificationare presented for large scale systems, they are the leastsquareapproximationand the rational fraction approximation.