f=521=107542 1 U,- U=s,=y2 (n-1) =0.161mm △0.5 U0=35 =0.289 Uc)=VU4)2+Ve2=0.331 ( ) ( ) ( ) ( ) ( ) ( ) ( ) 0.331 0.289 3 0.5 3 0.161 1 107.542 5 1 2 2 2 5 1 = + = = =  = = − − = = = =  = C f A f B f B f i f A f i i U U U U m m n n f f U s f f