Abstract: A refrigerant amount determining device includes: an operation data acquiring unit configured to acquire operation data of an air conditioning system; a calculating unit configured to calculate a refrigerant amount index value from the operation data acquired; an inferring unit configured to infer information regarding correction of the refrigerant amount index value using a correction model and at least one of the acquired operation data or the calculated refrigerant amount index value; and a determining unit configured to determine a refrigerant amount of the air conditioning system based on the information regarding correction of the refrigerant amount index value.

Abstract: An object is to provide a device that can measure a moving time (velocity) of a single particle with high accuracy, and an ion current measuring apparatus and a zeta potential measuring apparatus with the device, and an ion current measuring method and a zeta potential measuring method. The object can be achieved by a device used for measurement of ion current, the device including: a substrate; and a channel formed in the substrate. The channel includes a sample liquid supply channel, a sample collection channel, and constricted channel formed between the sample liquid supply channel and the sample collection channel. The constricted channel includes three or more constricted parts each formed with a protrusion part, the three or more constricted parts are formed substantially straight in a direction from the sample liquid supply channel to the sample collection channel, and when the width of each of the constricted parts is defined as 1, the spacing between adjacent constricted parts is 0.5 to 3.