由u1=0可计算tn U L Pepl- pepl (2-P1) Pit Piep e"=0 In P1 P 2 epic er2-pit e P P2=p 由dn/dt可确定u为极小值的时间t P n2em-n2e=0()= =已 P2-Put 2 n 2t P2-1由 uL= 0 可计算 tm 0 1 2 1 − 2 = p t p t p e p e p p t p t p t e e e p p 2 ( ) 2 1 1 2 2 1 ( ) − = = 2 1 2 1 ln p p p p t m − = 由 duL / dt 可确定uL为极小值的时间t 0 1 2 2 2 2 1 − = p t p t p e p e p p t p t p t e e e p p ( ) 2 1 2 1 1 2 − = = m t p p p p t 2 ln( ) 2 1 2 2 1 = − = ( ) ( ) 1 2 1 2 2 1 0 p t p t L P e P e P P U u − − − =