NaY(WO 4 ) 2 :Tb 3? powders with different sizes and morphologies were synthesized by the hydrothermal process. The surfactants and reaction times have obvious effects on sizes and morphologies of samples. When there is the addition of an equimolar combination of oleic acid and oleylamine and the reaction time of 10 h, uniform morphology of octahedron can be formed. As indicated by the FTIR spectra, the enhanced adsorption of oleic acid in the presence of oleylamine leads to the good formation of octahedral NaY(WO 4 ) 2 :Tb 3? powders. Surfactants will selectively absorb on the surface of the growing particles via physical and chemical effects, which leads to different growing rates along corresponding directions and induces the formation of octahedral morphology. Under the ultraviolet excitation, NaY(WO 4 ):Tb 3? powders show dominant green emission originating from the 5 D 4 ? 7 F 5 transition of Tb 3? ions.

Energy conservation and environmental protection is the theme of today's world. The Heating Ventilation and Air Conditioning system (HVAC) system with high energy consumption has attracted the attention of experts and scholars in this field. Natural ventilation is considered to be one of the most promising passive strategies for reducing building energy consumption and to improve indoor air quality and thermal comfort. The indoor air treatment technology of electric fan assisted by air-conditioner in hot summer is both energy-saving and effective. Reasonable air distribution is beneficial to further reduce the energy consumption of HVAC system. This study focuses on the joint management of indoor natural ventilation environment by coupling ceiling fan with air conditioner. The mathematical physical models of three different kinds of air treatment schemes, i.e., fan, air conditioner, air conditioner coupled by electric fan, were established in the same working room with natural ventilation openings. In numerical simulation, indoor air distribution is changed by adjusting the installation mode of electric fan and air conditioner.The Predicted Mean Vote (PMV), Predicted Percent Dissatisfied (PPD) and age of air were used to evaluate the comfort level of various air distribution modes. Finally, it was pointed out that indoor air distribution would be more uniform and indoor thermal comfort would be improved only when the air supply direction of fan or air conditioner was consistent with the direction of mainstream air supply. The above results were also verified in Chamber tests with human subjects.

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