Technical Program

TECHNICAL PROGRAM Wednesday, 9:00-10:30 Wednesday, 11:00-12:40 WA-03 WB-02 Wednesday, 9:00-10:30 - POT/081/H Wednesday, 11:00-12:40 - POT/051/H Opening Session and Plenary Collaborative Transportation Presentation by the Winner of the GOR Science Award 2019 Stream: Logistics and Freight Transportation Invited session Stream: Plenary Presentations Chair: Margaretha Gansterer Invited session Chair: Anita Schöbel 1 - Dispatching of Multiple Load Automated Guided Vehicles based on Adaptive Large Neighborhood 1 - Plenary Presentation of the GOR Science Award Win- search ner 2019 Patrick Boden, Hannes Hahne, Sebastian Rank, Thorsten Or 2019 Schmidt The winner of the GOR Science Award Winner 2019 will be an- This article is dedicated to the aspect of dispatching within the con- nounced during this session. After a short laudatio the winner will trol process of Multiple Load Automated Guided Vehicles (MLAGV). present his plenary talk. In contrast to more common single load AGV, MLAGV are able to transport more than one load. This is accompanied with a significant increase of possibilities to assign transportation jobs to the vehicles. Against the background of high transportation system performance, this results in the challenge of efficiently assigning/dispatching pend- ing load transports to available transport resources. In general, dispatching is considered as a challenging algorithmic problem (see Sin- riech 2002). The common way to solve the outlined problem is to select the next transportation job for the (ML)AGV by predefined dispatching rules. This, for example, can be the selection of the nearest location for load pick-up or drop off (see Co 1991). These static rules typically only consider the next activity to be executed. This, on the one hand, leads to transparent dispatching decisions and a short solution genera- tion/computational time. On the other hand, results from literature in- dicate that high performance reserves are still remaining by using these simple approaches (see Sinriech 2002). In contrast to this we modeled the problem as Dial a Ride Problem (DARP, see Cordeau 2003) and solved a bunch of instances by the Branch and Cut algorithm. Clearly, this approach led to good solutions but is only applicable for small problem sizes due to extensive computational times. Since the dispatching of Multiple Load Automated Guided Vehicles is an online decision problem, an approach which is able to solve larger problem sizes within seconds must be found and applied. So, in order to be able to dispatch an MLAGV fleet, a heuristic solution was identified and implemented. The heuristic is based on the Adap- tive Large Neighborhood Search (ALNS) presented by Ropke (2006). Since this heuristic was originally developed for the Pickup and Deliv- ery Problem with Time Windows, further constraints were considered to generate feasible solutions also for the DARP context. We demonstrate that this heuristic approach solves all the instances for- mer created for Branch and Cut algorithm with only small/acceptable loss of optimality but in significantly shorter time. The performance was investigated using static test instances related to a real MLAGV application in the semiconductor industry. References Co (1991), A review of research on AGVS vehicle management. Cordeau (2003), A Branch-and-Cut Algorithm for the Dial- a-Ride Problem. Ropke (2006), An Adaptive Large Neighborhood Search Heuristic for the Pickup and Delivery Problem with Time Windows. Sinriech (2002), A dynamic scheduling algorithm for a multiple-load multiple-carrier system. 2 - Combinatorial Exchanges with Financially Con- strained Buyers for Airport Time Slots Richard Littmann, Martin Bichler, Stefan Waldherr This talk is motivated by the exchange of airport timeslots granting rights for landing or take-off at crowded airports. Buyers are inter- ested in bundles of slots and need to financially compensate the previ- ous owner of a timeslot. In practice buyers are often financially constrained. We aim for an allocation and prices that maximize the gains from trade and are stable, i.e. no subset of the participants can deviate to their mutual benefit. Bichler and Waldherr (2017) showed that finding stable prices in combinatorial exchanges with financially constrained buyers is Sigma-2-p 1 WB-03 OR2019 – Dresden hard. We use bi-level mixed-integer programs to model these markets first-come-first-served policy. It can be shown that overall the newly and develop algorithms to solve these problems. We then compare developed reverse nested booking limit approach leads to the best re- the outcome to that of a market where buyers can only reveal budget- sults. Based on these results, some implications for future research capped valuations. in the field of revenue management for make-to-order production are We report experimental results on the benefits of budget-constraints derived. regarding social welfare and stability compared, and the instance sizes that we can expect to solve in practice. 2 - Simulation-Based Approach for Upselling in the Air- line Industry 3 - Decision support for sustainable regional food distri- Davina Hartmann, Jochen Gönsch, Sebastian Koch, Robert bution Klein, Claudius Steinhardt Christina Scharpenberg, Jutta Geldermann Consider a well-known situation in air traffic: after purchasing a cer- An increasing demand for regional products can be observed in Ger- tain fare, an upgrade is offered to you for a specific amount of money, many. Consumers associate inter alia freshness, good quality and en- e.g. bigger legroom for 8 EUR . This is a so-called upsell offer. Air- vironmental friendliness with regional products. Two main advantages lines try to capitalize on the willingness to pay of the travelers. Both of purchasing food regional are freshness due to short travelling dis- parties benefit: the airline might increase its revenue and the customer tances and strengthening the local economy. To keep transport dis- might receive a more personal offer, in the above-mentioned case ad- tances as short as possible and to offer a broad variety of local prod- ditional comfort during her/his flight. The difficulty of this problem ucts, supermarkets cooperate with small, regional producers. So far, consists in not knowing the exact willingness to pay and in the calcu- this concept involves an increasing organizational and logistical effort lation of the conditional purchase probabilities of the customers who due to a lack of standardization and due to special requirements of re- already bought a ticket. Furthermore, after the initial ticket purchase, gional producers. This tends to higher costs of the logistics processes the airline has more information about these particular customers com- especially at a ’last mile’ and a ’first mile’. Therefore, we investigated pared to random ones. different vehicle routing strategies for the regional food distribution We differentiate two intervals of time: the booking horizon and the regarding their transport cost structure and transport emissions. Spe- upsell horizon. First, during the booking horizon, random customers cial attention is given to a fair cost distribution between the business arrive and choose among the products offered the one that maximizes partners. Our goal is to minimize costs and emissions caused by the their utility. Thus, at the end of the booking horizon, there is a certain transport through product bundling of multiple regional producers to state of remaining capacity and tickets sold. If free seats of the higher- find a more sustainable solution for the regional transport problem. quality classes are left, the company can offer upsells, i.e. upgrades for which the customer pays a certain amount of money. The upsell horizon ends when either all high-quality seats are occupied or the air- plane takes off. When doors close, the value of unsold seats drops to zero. We focus on the problem the company faces during the upsell WB-03 horizon. After the booking horizon and before the upsell horizon the Wednesday, 11:00-12:40 - POT/081/H company has to decide on prices of the upsells. To do so, we suggest a simulation-based optimization model. We evaluate it with different Revenue Management and Pricing test instances assuming that customer choice behavior in the booking horizon follows a multinomial-logit model. Stream: Revenue Management and Pricing 3 - PAUL: Insourcing the Passenger Demand Forecast- Invited session ing System for Revenue Management at DB Fern- Chair: Robert Klein verkehr - Lessons Learned from the First Year Valentin Wagner, Stephan Dlugosz, Sang-Hyeun Park, Philipp 1 - Booking Limit based Revenue Management Ap- Bartke proaches for Make-to-Order Production Nina Lohnert, Kathrin Fischer Railway Revenue Management offers great opportunities to increase revenues in practice and therefore is a common method in passenger Due to the customization of products, variant diversity in production rail business. One essential component of a Railway Revenue Manage- has been increasing enormously in recent years. This forces companies ment system is an accurate forecast of future demand. The Revenue to redesign their production strategies, and more and more companies Management System at Deutsche Bahn Fernverkehr (DB), a leading apply the make-to-order principle where production only starts after an provider for long-distance passenger transportation in Germany with order has arrived and also has been accepted. Due to capacity restric- over 140 million passengers each year, was based on a third-party sys- tions, however, not every order can be accepted and hence, acceptance tem designed for airline carriers. Based on the fundamental importance decisions have to be made. Since the products have a high degree of of the demand forecast, DB decided in 2017 to develop its own fore- individualization, demand and the customers themselves are strongly cast environment PAUL (Prognose AUsLastung) to replace the legacy heterogeneous. Additionally, demand is usually stochastic, i.e. it is forecasting system utilized until then. Finding the most appropriate fluctuating over the time and difficult to predict.

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