Visible light communication based on light-emitting diodes (LEDs) has become a promising candidate by providing high data rates, low latency, and secure communication for underwater environments. In this paper, a self-designed common-anode GaN-based five-
SO2 monitoring in the flue gas of a coal burning boiler is important for environmental protection. The nonlinearity of practical condition causes deviation from theoretical law. On the basis of the Lambert-Beer Law, a new four-step calibration method is i