I discovered a mechanism of excitation of positive energy (positive Krein sign) modes by dissipative and non-dissipative non-conservative forces [1], which has found applications in the problems of acoustics of frictions as well as in the theory of magnetohydrodynamics dynamo [2]. The latter work was admitted by Helmholtz-Zentrum Dresden-Rossendorf (HZDR) as the research highlight of 2009.
[1] O.N. Kirillov (2009) Campbell diagrams of weakly anisotropic flexible rotors. Proc. of the Royal Society A 465(2109): 2703-2723
[2] O.N. Kirillov, U. Guenther, F. Stefani (2009) Determining role of Krein signature for three dimensional Arnold tongues of oscillatory dynamos. Physical Review E, 79: 1 016205