human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge groups authors who co-authored the same paper.

Details of the hypergraph:
Center hyperedge (induced by source paper "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.

Includes members:
  Member "A survey of the application of gamma processes in maintenance":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "Condition-based dynamic maintenance operations planning & grouping. Application to commercial heavy vehicles")

Question: Please tell me which research area the co-authored paper (i.e., the source paper of the center hyperedge) belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Engineering