1. Institute of Environmental Engineering, RWTH Aachen University, Mies-van-der-Rohe-Str. 1, Aachen 52074, Germany
2. GVB GmbH, Nordstern – Park 2, Herzogenrath 52134, Germany
3. Philips Group Innovation, Research, High Tech Campus 4, 1.518, Eindhoven 5656 AE, The Netherlands