Objectives: Fine particulate matter (PM_2.5) is the principal air pollutant and poses a serious threat to public health. This study explored the effects of PM_2.5 on the action spectrum of ultraviolet radiation for vitamin D production (UV_vitD) received by manikin surfaces. Methods: Multi-inclination angle ultraviolet radiation monitoring was conducted with different concentrations of PM_2.5. Combining monitoring data with the PM_2.5 concentration, solar elevation angle (SEA), and inclination angle, a UV_vitD exposure model for human body multi-inclined surfaces was constructed through a multiple linear regression analysis. A 3D manikin model was used to examine the PM_2.5 effects on UV_vitD received by the manikin surface. Results: When PM_2.5 concentrations ranged from 35 μg/m³ to 100 μg/m³ (average concentration of PM_2.5 in this range: 62 μg/m³), the UV_vitD received by the whole body was reduced by approximately 8.45% to 19.82% compared with the UV_vitD received when PM_2.5 concentrations ranged from 6 μg/m³ to 35 μg/m³ (average concentration of PM_2.5 in this range: 17 μg/m³) with SEAs between 30° and 50°. Moreover, the UV_vitD dose was reduced by 11.82% in the above comparisons. When further comparing PM_2.5 concentrations from 100 μg/m³ to 161 μg/m³ (average concentration of PM_2.5 in this range: 132 μg/m³) with those from 6 μg/m³ to 35 μg/m³ (average concentration of PM_2.5 in this range: 17 μg/m³), the UV_vitD received by the whole body was reduced by approximately 21.6% to 50.64% at SEAs between 30° and 50°. The UVvitD dose was reduced by 30.2%. Conclusions: The occurrence of PM_2.5 obviously reduced the UV_vitD received by the manikin surface.

This paper presents an observer-based robust control (ORC) scheme, combining perturbation observers with fractional-order sliding-mode regulators, for the current control of rotor-side converter (RSC) of a doubly-fed induction generator (DFIG). Perturbation states are defined to describe the interactions between d-axis and q-axis rotor current loops. The decoupled current control of RSC is realized via fractional-order sliding-mode output feedback control and perturbation compensation based on the estimation states obtained by perturbation observers. The proposed ORC scheme does not require any parameters of DFIG and it is robust to system uncertainties and external disturbances. Experimental tests are undertaken on a hardware-in-the-loop DFIG system to verify the control performance of ORC scheme.