Search

To improve the utilization of land resources, in recent years, there has been an increase in the design and construction of over-track buildings in metro depots in China. However, there are daily tasks such as testing, parking, and maintenance of metro trains in the depot, vibration induced by trains in those tasks may exert impact upon the residents living in the buildings over the metro depots. In this paper, detailed on-site measurements were carried out to investigate the source and transmission characteristics of train-induced vibrations in the metro depot. The main results indicated that (i) the magnitudes of train-induced vibration on the testing lines and throat areas are greater than other areas, and the issue of environmental vibrations induced by trains in the building near these areas need to be given more attention. (ii) Traininduced vibrations are more attenuated from the ground to the platform and less attenuated from the platform to the building floor, and most vibration acceleration levels below 30 Hz are even amplified during the transmission from the platform to the floors in the building, which could be because of the matching of the frequencies of train-induced vibrations and the natural frequencies of the superstructure. [ABSTRACT FROM AUTHOR]

Electromagnetic suspension is considered as a widely-used type of maglev train systems. It has been successfully used recently in Changsha Maglev Express (CME), China. Great research interests and engineering efforts have been focused on increasing the operation speed of such an environment-friendly low-speed maglev type to 200 km/h in order to meet the requirement of inter-city transportation, which has not been realized yet. However, at a higher speed, there is a considerable levitation force drop at the front of vehicles due to the pronounced eddy current effect. The electromagnet modules are more likely to saturate. An optimized electromagnet design is required for the medium-speed maglev train to achieve better levitation capability, weaker vibration, and more comfortable ride. Based on the actual parameters and operation data of CME, this paper uses the three-dimensional finite element analysis method to fully analyze the occurrence of magnetic saturation and its adverse effects. A novel structure design of electromagnet module coping with the problem of magnetic saturation is proposed to improve the levitation performance. The study also puts forward a three-controller system on the electromagnet module at the front of the vehicles which can effectively ease the imbalance of levitation forces. [ABSTRACT FROM AUTHOR]

This paper applies Bourdieu's theory of the scientific field to examine the sources of authority, reasons for conflict, and group dynamics in an isotope lab at a Chinese university. After 7 months of participant observation and non-structured interviews, I found that theoretical capital and technological capital are both used in the isotope lab. While both are associated with scientific authority, it was theoretical capital that determined lab members' social authority. Dominant and subordinate members of the lab applied different strategies to advance their interests. Conflicts of interest induced competition between the holders of theoretical and technological capital, which in turn caused interpersonal conflict. The specificity of the field of geoscience determines the relative power of technological and theoretical capital, and the low autonomy of the scientific field in China strengthens that hierarchy. I find that this hierarchy of scientific capital in the broader field can have a considerable impact on the social construction of experimental results in the local settings. [ABSTRACT FROM AUTHOR]