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: "On the use of on-line detection for maintenance of gradually deteriorating systems"
  Abstract: This paper deals with condition-based maintenance and non-stationary degradation process due to sudden changes. This is an attempt to propose an adaptive maintenance policy based on the on-line change detection procedure which can help to detect switches from a nominal mode to an accelerated mode in a non-informative context about the change mode time.

Connected through hyperedge HE-1 (induced by source paper "A survey of the application of gamma processes in maintenance"):
  with members:
    - "Condition-based dynamic maintenance operations planning & grouping. Application to commercial heavy vehicles"

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: Engineering