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Spherical BaWO 4 :Tb 3+ phosphors were prepared by the polyol method and postannealed at 900°C. A variety of properties were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform IR spectra, low-voltage cathodoluminescence, photoluminescence spectra, and lifetime. The as-prepared phosphors were well-crystallized under relatively low synthesis temperature ͑160°C͒ and composed of spherical particles with an average size of 100 nm. After postannealing treatment, crystallinity of the phosphors is significantly improved and average particle size is increased to around 220 nm. Under low-voltage ͑ഛ4.5 kV͒ excitation of electron beam, bright green cathodoluminescence was observed, which is attributed to the characteristic emissions from Tb 3+ ͑ 5 D 3 -7 F J and 5 D 4 -7 F J transitions͒. The luminance was significantly improved from 141 to 4866 cd/m 2 after postannealing, which is mostly attributed to the improvement of crystallinity.

This study presents a framework for dynamic analysis of a coupled system of high-speed maglev train and curved viaduct. A series of trajectory coordinates are used to define the motion of maglev vehicles moving over a horizontally curved track, the stiffness and damping matrices of the equations can be thus reduced into those of the straight track. The curved viaduct system is modeled in the global coordinate system using the finite element method, in which the inner and outer rails in the different horizontal planes are duly included. The electromagnet force-air gap model is adopted for the maglev vehicle via its electromagnets and rails on the viaduct, by appropriate transformation of coordinates. By applying the proposed framework to the Shanghai maglev line, curved path-induced dynamic responses and characteristics of the vehicle are explored, which agree well with the measurement ones. The dynamic responses of the curved viaduct are also examined in the vertical, lateral and rotational directions by comparison with the straight viaduct. Moreover, the effect of various curve radii and cant deficiencies on the coupled system are investigated. The results show that for a maglev vehicle moving with an initial equilibrium state, its lateral and rotational response are mainly excited by track roughness. In addition to the track radius, cant deficiencies significantly affect the operational safety of the viaduct.