human: Given a node-centered hypergraph: <hypergraph>, where nodes represent authors and hyperedges represent groups of authors who co-authored the same paper.

Details of the hypergraph:
Center node: "Shunt voltage regulators for autonomous induction generators. Part I: principles of operation"
  Abstract: The paper gives the theoretical background of output voltage regulation for autonomous induction generators. Based on the equivalent circuit of an induction generator, conditions for maintaining constant voltage are derived at given reference, rotation speed and load changes. It is shown that, by adjusting the reactive power source connected to the induction generator terminals, it is possible to maintain the generator output voltage within a given operating range. Limits of such regulation are also shown and explained. A simple controller scheme is given to enforce the theoretical aspects, with extended simulation results presented.

Connected through hyperedge HE-1 (induced by source paper "Shunt voltage regulators for autonomous induction generators. Part II: circuits and systems"):
  with members:
    (none)

Question: Please tell me which research area the center author belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Computer science