Calibrating a model can be a very time consuming and difficult task when modelling. In this exercises, for the sake of simplicity, we have decided to use a very simple approach. Many variations of the original model will be run and the one which is closest to the measured data will be chosen as the best fit. Of course, the calibration could (and should) be carried in a better ans faster way by using a much more reliable optimization procedure, such as Newton-Raphson method, or Levenberg-Marquardt algorithms, among the simplest ones.