Abstract: A control method for preparing crop nutrient solution, applied in a regulating device, obtains growth data of crops, and determines a growth state of the crops according to the growth data of the crops. The proportion of the nutrient solution required by the crops is determined according to the growth states of the crops, and the culture solution is adjusted according to the proportion of the nutrient solution. After a preset time period, updated growth state of the crops is determined. When the culture solution does not meet the proportion of the nutrient solution corresponding to the updated growth state, the culture solution is adjusted again until the culture solution meet the proportion of the nutrient solution corresponding to the growth state of the crops.

Abstract: An intraocular pressure inspection device includes an intraocular pressure detection unit, a high-precision positioning system and a wide-area positioning system, wherein according to the position of the intraocular pressure detection unit, a set of high-precision coordinates output by the high-precision positioning system and a set of wide-area coordinates output by the wide-area positioning system are integrated in appropriate weights to obtain a set of more precise integrated coordinate. The above-mentioned intraocular pressure inspection device can prevent the intraocular pressure detection unit from failing to operate once it is not in the working area of the high-precision positioning system.

Abstract: A variable switching frequency power supply apparatus includes a main transformer, a voltage detection unit, a pulse width modulation control unit and a switch unit. The voltage detection unit is electrically connected to the main transformer. The pulse width modulation control unit is electrically connected to the voltage detection unit. The switch unit is electrically connected to the pulse width modulation control unit and the main transformer. The main transformer transforms an input voltage into an output voltage according to a switching frequency of the switch unit. The voltage detection unit detects the input voltage and then informs the pulse width modulation control unit. The pulse width modulation control unit is configured to control the switching frequency of the switch unit according to a voltage absolute value of the input voltage.

Abstract: A variable switching frequency power supply apparatus includes a main transformer, a voltage detection unit, a pulse width modulation control unit and a switch unit. The voltage detection unit is electrically connected to the main transformer. The pulse width modulation control unit is electrically connected to the voltage detection unit. The switch unit is electrically connected to the pulse width modulation control unit and the main transformer. The main transformer transforms an input voltage into an output voltage according to a switching frequency of the switch unit. The voltage detection unit detects the input voltage and then informs the pulse width modulation control unit. The pulse width modulation control unit is configured to control the switching frequency of the switch unit according to a voltage absolute value of the input voltage.