I have organized, together with many collaborators and colleagues, quite a number of scientific conferences, workshops and other meetings. I have not kept track of all my activities in this respect. I was involved in the organization of several large scale international meetings to which I donated substantial amounts of time.
In my capacity as the Secretary of IMU (2007-2014), I supported the organization of the ICM 2010 in Hyderabad and the General Assembly in Bangalore, India, and helped to organize the ICM 2014 in Seoul and the General Assembly in Gyeongju, Korea.

Here are some past events at whose organization I was involved in:

1. ICM'98, TU Berlin, August 17-28, 1998
2. International Conference on Operations Research 1994, TU Berlin, August 30 -- September 2, 1994
3. Symposium on Mathematical Programming -- The State of the Art, Bonn 1982

My research group at ZIB organizes about half a dozen workshops per year, usually addressing our current research and application areas. The last international conference organized by this group was the CPAIOR 2011, May 23-27, 2011 at ZIB, Berlin.

In addition, I was involved in the local organization of the 25th IFIP TC7 Conference on System Modeling and Optimization (September 12-16, 2011, at TU Berlin).

I was a member of the organizing committee of the 21th International Symposium on Mathematical Programming, Berlin, August 12-24, 2012.

Currently I am a member of the local organizing committee of the 7th European Congress of Mathematics that will take place in the buildings of TU Berlin, July 18-22, 2016.