We present proofs of two classical theorems. The first one, due to Darboux and Sauer, states that infinitesimal rigidity is a projective invariant; the other one establishes relations (infinitesimal Pogorelov maps) between the infinitesimal motions of a Euclidean framework and of its hyperbolic and spherical images. The arguments use the static formulation of infinitesimal rigidity. The duality...

this paper proposes a novel approach for coherent generators online clustering in a large power system following a wide area disturbance. an interconnected power system may become unstable due to severe contingency when it is operated close to the stability boundaries. hence, the bulk power system controlled islanding is the last resort to prevent catastrophic cascading outages and wide area bl...