Another possibility :
http://www.acd-serres.fr/fr-8953-4967-6 ... -50-m.html

yes robert mellet's site, I had this in my favorites for a while but I didn't know what to do with it until recently ... concept a little abstract but remarkably clear .... I found an application to these equations ... For the sensor: I am at 13 euros / m2 with the background towards the university ...

This physicist's site found by lilian07 (I was unaware of it) is more than remarkable of clarity of work to read in full, very clear on a lot of varied concepts to know !! http://robert.mellet.pagesperso-orange.fr/index.htm http://robert.mellet.pagesperso-orange.fr/diff/diff_02.htm http: // rober ...

Not especially, a physicist of materials with various microscopic and macroscopic quantum effects, retired, after experimental as well as theoretical studies !! I like to go from theory to concrete realization and vice versa. These links are elementary bases, among many other ...