The Operations, Planning, Accounting and Control (OPAC) group is one of the capacity groups within the Department of Industrial Engineering and Innovation Sciences of Eindhoven University of Technology. The focus of the research within OPAC is on the control of operational processes. In these processes, scarce resources (machines, people, transportation means) are used to transform incoming materials into outgoing materials or to move materials from one place to another. With a smart control of operational processes, these activities can be done faster or one can do more work with the same or even less resources. To obtain such a smart control, one has to address decisions at strategic, tactical and operational level.