Particle size-energy distribution

I am not chemist, I am mathematician and interested in Population Balance Equations. I have a question about particle size-(breakage) energy distribution which mentioned in this article: <http://www.sciencedirect.com/science/article/pii/S0032591011001458>. 


In this paper, author says (in top of section 3.2) he divide size and energy interval to 100 intervals. I divide size interval (0-6 mm) to 100 intervals but I don't know how can I divide energy interval. Is there anybody can help me?


