A column-generation matheuristic approach for optimizing first-mile ridesharing services with publicly- and privately-owned autonomous vehicles

The burden of first-mile connection to public transit stations is a key barrier that discourages riders from taking public transportation. Public transit agencies typically operate a modest fleet of vehicles to provide first-mile services due to the high operating costs, thus failing to adequately meet the first-mile travel demands,...

The flexible airport bus and last-mile ride-sharing problem: Math-heuristic and metaheuristic approaches

Airport buses play a crucial role in addressing the last-mile problem of air travel, especially in cities and countries lacking inner-city rail transit systems. Nevertheless, airport buses are currently witnessing a decline in ridership due to drawbacks such as long departure intervals, inflexible stops, and considerable distances between...

Optimising OR planning: Sequencing surgery groups while levelling bed occupancy

This research is conducted in collaboration with the Sophia Children's Hospital (SCH). The hospital wants to provide their patients with more detailed information about when a patient is approximately scheduled to have a surgery. The first step is to create a model which optimises the operation room (OR) schedule and indicates when different...

Partial and complete replanning of an intermodal logistic system under disruptions

The exclusive and excessive use of long-distance road transportation is not suitable way to reduce the negative environmental impacts of logistics systems. Intermodal transport, combining road with other transport modes, has the potential to reduce both operating costs and carbon footprints. One of the reasons for the low share of intermodal...

Optimizing Urban Multi-Energy Systems using Column Generation

Fleet Sizing and Scheduling of Electric Thin-Haul Aircraft: A Column Generation and Large Neighborhood Search Based Method

This Thesis proposes an optimisation model to minimize operational cost of a fleet of electric thin-haul aircraft under a minimum RPK (Revenue-Passenger Kilometer) constraint. A solution that minimises cost per RPK can be found by varying the minimum RPK level. The solutions describes how many aircraft are needed, as well as a schedule for each...

Scheduling multimodal alternative services for managing infrastructure maintenance possessions in railway networks

Highly utilized railway networks require regular infrastructure maintenance. Different track sections often need to be closed for entire days to carry out engineering works, which makes the regular timetables no longer feasible and thus adjusted railway services and temporary alternative services need to be planned. We introduce the...

Passenger-centered vulnerability assessment of railway networks

The performance and behaviour of critical infrastructure in case of disruptions is an important topic and we are still lacking of insights. Due to disruptions, infrastructure becomes unavailable and may force the trains and passengers to adapt. In this paper, we introduce a problem of railway network vulnerability from the perspective of...

Optimizing Outbound Baggage Handling at KLM

In order to handle the increase in baggage units, KLM needs to optimize the outbound baggage handling process. This study focuses on accurately modeling the outbound baggage handling process while minimizing the number of employees working on this process. The results are based upon data on the outbound baggage handling process at KLM in 2018....

Automated prioritised 3D dose-based MLC segment generation for step-and-shoot IMRT

Segmentation can degrade a high-quality dose distribution obtained by fluence map optimisation (FMO). A novel algorithm is proposed for generation of MLC segments to deliver an FMO plan with step-and-shoot IMRT while minimising quality loss. All beams are considered simultaneously while generating MLC segments for reproducing the 3D FMO dose...

Crew Scheduling Approach to Calculate the Crew Productivity of Flight Schedules

With cockpit crew costs being the second largest costs of an airline, making optimal use of the available crew is very important. The productivity of the crew is limited by the labor agreement and law regulations, which prevent the crew members from working irregularly or excessively. In this thesis we present several methods to solve the crew...

Intermodal Transport: Routing Vehicles and Scheduling Containers

In intermodal transport multiple types of vehicles are used to transport containers. If the routes of the vehicles are known, then the container allocation can be optimized. This problem can be modelled as an integral multi-commodity min cost flow problem on a time-space graph. This model has an arc-based and path-based form. In this thesis, the...

Solution methods for the tray optimization problem

In order to perform medical surgeries, hospitals keep large inventories of surgical instruments. These instruments need to be sterilized before each surgery. Typically the instruments are kept in trays. Multiple trays may be required for a single surgery, while a single tray may contain instruments that are required for multiple surgical...