90B06 Transportation, logistics
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SAP's decision support systems for optimized supply network planning rely on mixed-integer programming as the core engine to compute optimal or near-optimal solutions. The modeling flexibility and the optimality guarantees provided by mixed-integer programming greatly aid the design of a robust and future-proof decision support system for a large and diverse customer base. In this paper we describe our coordinated efforts to ensure that the performance of the underlying solution algorithms matches the complexity of the large supply chain problems and tight time limits encountered in practice.
The airplane has changed the world in a tremendous way. Efficient scheduling of
airmen and aircrafts is of considerable importance for cost-effectiveness of compa-
nies.
Attentiveness of flight crew members is vital as fatigue can lead to severe accidents.
Therefore, duty times of flight crews are strictly limited. Long distance flights may
be difficult to schedule with only one set of crew members. Furthermore, pertu-
bations of the schedules may entail exchanging the entire crew, which confounds
multiday schedules. A new EU regulation introduced in-flight rest: a schedule may
extend pilots’ duty times if they rest for a certain time in designated crew compart-
ments provided aboard airplanes. Of course they have to be replaced in that period
of time.
This thesis examines the in-flight rest assignment problem, which is the decision
problem whether a given schedule allows for all crew members to take their compul-
sory rest. The problem can be seen as multimachine scheduling problem. Efficient
algorithms for special cases were developed and an alternative approach for entire
hard cases is discussed.