Lingering issues in fractional-bim.ipynb

[alessandrozocca]

Lingering issues in fractional-bim.ipynb:

• there are actually two models in the notebook, only one of which is fractional BIM. There should be two sections separating them and a new overarching title for the notebook, namely "Different profit formulations for BIM microchips production"
• related to the new title, the name of the file could change accordingly?
• preamble cells are outdated, delete and replace with the new one
• no story nor accompanying text for both models (fraction and subtraction, please copy it from the book (see Example 6)
• delete the functions and rearrange the code as to define the two Pyomo model directly
• the name of the concrete models should be different (maybe just use the current names of the functions?)