PhD thesis: Novel class of models developed for planning problems

Marloes Cremers her thesis studies two planning problems in the area of routing and scheduling by means of mathematical models and (numerical) optimization. First, a planning problem for a taxi company for the transport of elderly and disable people in which requests – partly known, partly unknown – are to be subcontracted or served by own vehicles. Second, a similar planning problem for a housing corporation in which known maintenance projects and future emergency incidents have to be assigned to subcontractors or mechanics employed by the corporation.

Characteristic for both problems is that now planning decisions have to be made on the known service requests while only probabilistic information is available on the relevant planning period. Moreover, during the planning period immediate (online) decisions on the arriving service requests are required.

A novel class of models is developed in which ideas from the research fields stochastic programming and online optimization are integrated. These models comprise two stages. In the first stage planning decisions are modeled, and in the second stage the online decisions concerning the arriving service requests. The expected future costs of the second stage are included in the first-stage objective. Considering the complexity of both planning problems, Cremers has chosen for a heuristic approach. Sophisticated heuristics have been developed for the subproblems, and simulation is applied to analyze the online second-stage problems. A genetic algorithm is used to find good first-stage solutions.

Curriculum vitae

Marloes Cremers (Eindhoven, 1979) studied econometrics en operations research in Groningen and conducted her PhD research at SOM research school of the Faculty of Economics and Business. She will be awarded her PhD on 9 April (2.45 pm). Het supervisors are prof.dr. M.H. van der Vlerk and prof.dr. W.K. Klein Haneveld. The thesis title is: Dynamic and stochastic planning problems with online decision making. A novel class of models.