Abstract: A photoelectric flowmeter circuit includes a circuit power supply end. The photoelectric flowmeter circuit also includes a light-emitting element, including a first end electrically connected to the circuit power supply end and a second end electrically connected to ground. The photoelectric flowmeter circuit also includes a photosensitive triode, including a collector electrically connected to the circuit power supply end and an emitter electrically connected to the ground. The photoelectric flowmeter circuit also includes a direct current (DC) blocking circuit. The photoelectric flowmeter circuit also includes a circuit output end electrically connected to the collector of the photosensitive triode through the DC blocking circuit.

Abstract: A method, device and system for updating a map of an unloading area (UA) of an open pit mine, which relate to the technical field of open pit mines. The method includes: acquiring one or more coordinates of one or more first preset positions of auxiliary operation equipment (11) during an operation (302), wherein the auxiliary operation equipment (11) trims a retaining wall (L) that acts as a physical boundary of the unloading area (UA) during the operation, and during the operation of the auxiliary operation equipment (11), each first preset position is located within the unloading area (UA); determining a first coordinate set (304), the first coordinate set (304) including coordinates among the one or more coordinates located outside of a first map of the unloading area (UA); and according to the first coordinate set (304), updating the first map into a second map (306).