1. a Department of Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK;, Email: sgiannis@merl-ltd.co.uk
2. b Department of Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK
3. c Airbus, New Filton House, Filton, Bristol BS99 7AR, UK
4. d Airbus, New Filton House, Filton, Bristol BS99 7AR, UK