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In order to study the effects of impedance forces of couplings on energy absorption in train crash, a dynamics model of train longitudinal crash was established. Taking maximum average acceleration, maximum instantaneous acceleration, and maximum plastic deformation of car body as optimization objectives, while taking the impedance forces of different couplings as optimization parameters, optimal solution set was obtained by NSGA-II algorithm. And then, a comprehensive evaluation system for the optimization objectives was established, and the optimal solution was selected. Crash acceleration of the train after optimization is less than that of train before optimization, which is due to the smaller interfacial force difference between two ends of the vehicles. [ABSTRACT FROM AUTHOR]

Objective: To compared 3 approaches to establishing Balb/c mouse models of hind-limb ischemia suitable for studies of regenerative medicine., Methods: Thirty eight-week-old male Balb/c mice were randomly divided into 3 groups for establishing models of hind-limb ischemia by both ligating and transecting the femoral artery proximal to the origin of the deep femoral artery branch, ligating the femoral artery proximal to the origin of the deep femoral artery branch, or ligating the femoral artery distal to the femoral artery trunk. The mice were continuously observed for 5 days after the operation, and hind-limb blood perfusion was monitored by laser Doppler imaging on the second postoperative day., Results: All the 3 surgical approaches caused blood flow block in the hind-limbs of the mice. In mice with ligation and transaction of the femoral artery proximal to the origin of the deep femoral artery branch, dry gangrene occurred in the whole hind-limb. Dry gangrene also occurred in the legs and paws of mice with ligation of the femoral artery proximal to the origin of the deep femoral artery branch. In mice with femoral artery ligation distal to the origin of the deep femoral artery branch, the sole of the foot was dry with scaling skin and necrosis of several digits; microscopically examination revealed a large quantity of necrotic muscles accompanied by muscle regeneration., Conclusion: Ligating the femoral artery distal to the origin of the deep femoral artery branch can be optimal for establishing Balb/c mouse models of hind-limb ischemia.