Humboldt-Universität zu Berlin | Wirtschaftswissenschaftliche Fakultät | High Dimensional Nonstationary Time Series | About us | News Feed | News 2015 | Research visit: National University of Singapore Research visit: National University of Singapore 04.09.2015. Simon Trimborn, IRTG student, was invited by the National University of Singapore for a two-week research stay in December. He will work together with Prof. Ying Chen.