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This paper reports on the development of high-speed railway systems in China. In addition, with respect to the characteristics of the high-speed train system, the relationship between various coupled systems that can affect train operation are analysed, including interactions between two vehicles, between a track and train, a pantograph/catenary and train, and airflow and a train. On the basis of this research, problems pertaining to the dynamics arising from high-speed operations are studied and the necessity for a study of the system dynamics of high-speed trains-considering all these interactions-is discussed. A theoretic framework for the analysis of the dynamics generated by coupled systems in highspeed trains is presented and the modelling methods for these coupled systems are outlined.

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To study the railway overhead wire's flexural wave motion that significantly affects the quality of current collection between pantograph and catenary, dynamic responses of a real catenary excited by different excitations are measured and analyzed by using a set of noncontact photogrammetric devices together with the finite-element simulation. Based on the measured and simulated results, the wave motion along the contact wire is investigated and some findings have been obtained. First, it is the first two dominant modal components in the catenary displacement responses that induce a beat phenomenon, and this beat phenomenon is increasingly obvious near the registration arm. Moreover, with the simulated displacement contour, catenary local vibration characteristics affected by the travelling wave can be clearly interpreted. Furthermore, the wave group velocity of contact wire in catenary is determined and verified to be approximately 139.18 m/s; in addition, treating the contact wire in the overhead wire system as an ideal string or a tensioned Euler beam will overestimate the corresponding group velocity with a relative error by about 13.21%.

Organic matter plays an important role in soil moisture variation. In order to know the effect of organic matter on soil moisture dynamics, this study compared the infiltration and evaporation of soils with different organic matter content. The results showed that increasing the organic matter content in a certain degree can suppress evaporation and infiltration of soil moisture, and hence improving water use efficiency. When the organic matter content reaches3.2%, effect of suppressing evaporation is most obvious.