Position dependent maintenance scheduling

Scheduling as a part of Operations Research deals with the allocation of limited resources (human resources, machines, etc.) to process a number of assignments under consideration of a predefined time slot, an objective, and specific constraints. Typically, any type of resources is called machine and an assignment is a job.

In our current research, we focus on problems considering machines with availability constraints. Machines deteriorate and must undergo service, i.e. maintenance operations are required, to restore the original state of the machine. The deterioration depends on the number of scheduled jobs on the machine and not, as typically assumed, on the length of scheduled jobs. Including different objectives and model restrictions, we analyze models with position dependent maintenance regarding their runtime complexity to derive strategies for real-world applications.

Contact person: Julius Hardt, Dr. Andreas Hipp

Airplane Boarding

Airplane boarding represents a process that usually is on the critical path of airplane turnaround. Hence, just a few minutes of savings per flight can lead to immense cost reductions. The aim of our research is to determine factors influencing boarding time by applying analytical models and methods as well as by evaluating real data collected at the airport, and to analyze which characteristics optimal boarding strategies have.
Based on the results, applicable efficient boarding strategies can be derived.
In a current research project, passenger preferences were determined and analytical models were used to develop boarding strategies that both minimize boarding time and also consider customer preferences.

Contact persons: Dr. Finn Meissner

Storage and retrieval strategies for compact storage systems

The scarcity of space in cities and the growing e-commerce with continually decreasing delivery times pose new challenges to logistics. A new type of warehouse with both high storage density and high throughput is expected to provide a solutiontackle these challenges.

The aim of our research is to evaluate the new type of warehouse and to embed it into the existing research on warehouse types. For this purpose, relevant problems are to be identified and analyzed.

In a current research project, a compact storage system is being developed together with the Professorship Technology of Logistics Systems and a partner from practice. The problem descriptions derived from the storage type are examined regarding their characteristics. Taking into account key performance indicators – e.g. throughput and energy consumption – storage and retrieval strategies are developed. The evaluation is carried out on the model and on the real system.

Contact persons: Nicolas Fauvé

Rebound Effects in Transportation

Sometimes measurements taken to increase resource efficiency do not reach the estimated magnitude, as part of the reduction vanishes due to the reaction of entities to the changed environment. This so-called rebound effect is intensively discussed in the energy sector literature, yet surprisingly little is found for transportation. Our research showed that rebound effects occur in logistics as well. Current research is concerned with the more precise quantification of the effect as well as possibilities for decision-makers to counteract the effect.

Contact person: Dr. Finn Meissner