RESUMO
The wheel polygonization and rail corrugation are typical wheel-rail periodic wear problems, which seriously affect the safe operation of high-speed railways. In the present paper, the interaction between the wheel polygon and the rail corrugation in the long-slope section of high-speed railways is mainly studied based on theory of friction coupling vibration. Firstly, the simulation model of the wheel-rail contact model is established, as well as the polygonal wear of the wheel and the corrugated wear of the rail. Then, the stability analyses of the wheel-rail system with periodic wear are studied, in which the four working conditions of smooth rail-smooth wheel, polygonal wheel-smooth rail, smooth wheel-corrugated rail and polygonal wheel-corrugated rail are compared. Finally, the competition mechanisms between the wheel polygon and rail corrugation under different parameters are discussed, including the wheel-rail friction coefficient and the depth of periodic wear of the wheel-rail system. The numerical results show that both the periodic wear of the wheel and rail with certain relevance will increase the friction coupling vibration of the wheel-rail system, which may aggravate the subsequent relevant wheel polygonal and rail corrugation wear. With the increase of the friction coefficient between wheel and rail, as well as the depth of the wheel polygon and rail corrugation, the vibration trend of the friction coupling vibration of the wheel-rail system increases gradually. Moreover, the proportion of the wheel polygon's influence on the friction coupling vibration of the wheel-rail system is greater than that of rail corrugation.
RESUMO
Herein, a novel stacked hexagonal prism, Ag@Ni-MOF-1, was designed and developed as an integrated SERS platform not only for successfully catalyzing the in situ synthesis of DA-quinone under physiological pH, but also for establishing an approach for specific determination of Cys, an important species in the brain related to Alzheimer's disease (AD).
