1. Institute of Applied Analysis and Numerical Simulation, Universität Stuttgart 1 , Pfaffenwaldring 57, 70569 Stuttgart, Germany
2. Applied and Computational Mathematics, RWTH Aachen University 2 , Schinkelstraße 2, 52062 Aachen, Germany
3. Shenzhen International Center for Mathematics , Southern University of Science and Technology 3 , Shenzhen, China