Accuracy Improvement of Braking Force via Deceleration Feedback Functions Applied to Braking Systems.

Currently, braking control systems used in regional railways are open-loop systems, such as metro and tramways. Given that the performance of braking can be influenced by issues such as wheel sliding or the properties of the friction components present in brake systems, our study puts forward a novel closed-loop mechanism to autonomously stabilize braking performance. It is able to keep train deceleration close to the target values required by the braking control unit (BCU), especially in terms of the electrical-pneumatic braking transform process. This method fully considers the friction efficiency characteristics of brake pads and encompasses running tests using rolling stock. The test results show that the technique is able to stabilize the actual deceleration at a closer rate to the target deceleration than before and avoid wheel sliding protection (WSP) action, especially during low-speed periods.

[Ultrastructural changes of the skeletal muscle cells of rats subjected to exhausting exercises and the protective effect of vitamin E].

OBJECTIVE: To investigate the ultrastructural changes of the mitochondria in the skeletal muscle cells of rats subjected to repeated exhausting exercises on treadmill and the protective effect of oral vitamin E. METHODS: Thirty male SD rats were randomized into control group (n=10), exhausting exercise group (n=10) and exhausting exercise group with oral vitamin E treatment (n=10), with the latter two groups taking repeated exhausting running exercises on the treadmill in a course of 4 weeks. At the end of the course of exercises, the rats were sacrificed and the quadriceps femoris muscles isolated for observation the ultrastructures of the skeletal muscle cells by transmission electron microscope (TEM). RESULTS: After 4-week exhausting exercises, the myofilaments of the skeletal muscle were seen in disordered alignment, and the mitochondria exhibited abnormal morphological changes of swelling and vacuolar degeneration. In vitamin E-treated rats also undertaking the exercise, the ultrastructures of the skeletal muscle cells were almost normal as compared with the normal control group. CONCLUSION: Vitamin E can protect the function of the skeletal muscle mitochondria of rats taking repeated exhausting exercises.

[Effect of antioxidant vitamins on the exercise performance of rats].

OBJECTIVE: To investigate the effect of antioxidant vitamins (vitamin E and vitamin C) on the exercise performance of rats. METHODS: Fifty male SD rats were randomly divided into control group (C), exhausting exercise control group (E), vitamin E group (M1), vitamin C group (M2) and vitamin E plus vitamin C group (M3). The rats in the exercising groups (E, M1, M2, M3) were propelled for repeated exhausting runs on the treadmill for 4 weeks. RESULTS: Exclusive use of oral vitamin E or in combination with vitamin C significantly improved the body mass, total exercise treadmill length and net mass of rat quadriceps femoris after the 4-week exercise. No difference was noted between the rats taking oral vitamin C or E alone. The rats in M1, M2 and M3 groups had lower malondialdehyde (MDA) and free calcium content in the quadriceps femoris than the control rats, and SOD activities in the quadriceps femoris mitochondria of rats in the former 3 groups were significantly higher than those of the control group. CONCLUSIONS: Vitamin E can protect the mitochondria in the skeletal muscles and improve the exercise performance of rats, the effect of which can be enhanced by vitamin C, but vitamin C alone can not sufficiently achieve the effects.