Boris P. Belinskiy, C. Maeve McCarthy, Terry J. Walters, Optimal turbines in the absence of an attached mass, European Series in Applied and Industrial Mathematics: Control, Optimisation and Calculus of Variations, 9 (2003), pp. 217-230.

We minimize, with respect to shape, the moment of inertia of a turbine having the given lowest eigenfrequency of the torsional oscillations. The necessary conditions of optimality in conjunction with certain physical parameters admit a unique optimal design.