What are the Di parameters in the power grid model?

The $D_i$ parameters in the power grid model are the damping coefficients for the different rotors; there is a typo in the equations (slide 9 of Lecture 2-1), as each rotor has its own damping coefficient (the first equation notation is $D_1$, the second has to be corrected to $D_2$).

--Elisa 15:11, 8 October 2007 (PDT)