A demand forecasting system and a demand forecasting method capable of forecasting demands for IT resources in a data center accurately are provided. This is done by, at a given time, determining future values of control values and simulating, in a simulation module, the behavior of the plant up to a given future time. The sensor may be calibrated using a calibration set of one or more matched sensor and reference analyte data pairs. In one embodiment, based, at least in part, on whether the data represents a partial read, a determination is made as to whether to transmit, to the second machine, an explicit acknowledgement that the data was read from the first buffer. The position adjusting means includes a position adjusting detent formed at an outer circumference of a sensing disk and a roller pressed to the outer circumference of the sensing disk by a resilient member.