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Item type:Publication, Access status: with files , Integrierte Produktions- und Absatzplanung - Integration von Substitutionsentscheidungen in ein Produktionsprogrammplanungsmodell für konfigurierbare Produkte(2026); Manufacturers of configurable products must efficiently align demand volumes and capacities despite high product variety. This thesis introduces an optimization model for targeted product mix control under capacity constraints. Economic objectives and sales risks are considered simultaneously. A context-sensitive distance measure (“cpDist”) quantifies the market attractiveness of alternative configurations. This enables the anticipation of customer substitution behaviour within production planning.Publicationtype: Doctoral Thesis38 42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimierung des Energiemanagements durch Aggregatoren(2025); In this work, a mixed-integer linear optimization model is developed to depict the decision-making problem of energy aggregators (EAs), which includes the deployment planning of various types of flexible energy resources and the trading of energy on different markets for a set of households assigned to the EA. The central research contribution compared to previous works in the development of the EA model (EAM) is that, on the one hand, it represents a holistic approach, as different types of energy resources and energy markets are integrated into the aggregated energy management of a community of households, and on the other hand, it features a high level of detail in the modeling of the technical restrictions of energy resources, in particular power-to-heat systems with heat pumps. In a case study with two seasonal scenarios, each consisting of 62 days, the EAM is verified and validated for day-ahead planning for up to 111 households. The results show that the participating households can achieve clear economic added value through the EA and that this added value is based on complex synergies between the system components, which can only be exploited through holistic and differentiated modeling. Further analyses consider an additional improvement in the efficiency of EA energy management through the foresighted use of energy storage systems. Standardized strategies are identified that contribute to an increase in household trading surpluses for different constellations of days. In addition, a fairness analysis is carried out, which shows that the internal trading between households depicted in the EAM is problematic in terms of fairness, as the flexibility provided to the community is not sufficiently rewarded. An ex-post redistribution of the realized community surpluses is proposed as an approach to improve fairness between households. Furthermore, the EAM is considered in the context of local energy markets. For this purpose, a model of a local market is developed that is integrated into a higher-level day-ahead process together with the EAM, thereby iteratively depicting local energy trading between EAs. Application in a case study shows that the composition of EAs' households has a strong influence on the resulting trading relationships. For example, specialization of EAs in specific types of households, resulting in heterogeneity among EAs, is advantageous in terms of local market efficiency compared to a set of unspecialized and thus homogeneous EAs, which, on the other hand, results in more internal energy exchange between the households of the respective EAs. In the case of a heterogeneous composition of EAs, a further study analyzes the possibility of targeted market interventions to reduce line congestion. A comparison of four different approaches, each with nine variants, leads to the conclusion that such a market-based approach can contribute positively to reducing line congestion, but that the potential is limited and the approaches presented should therefore be considered as supporting other congestion management tools. In conclusion, it is clear that EAs can play an important role in future energy systems by providing economically efficient energy management for households. The EAM developed in this thesis represents a basic model for depicting the decision-making problems of such energy management. There are many configuration options and influencing factors that must be taken into account for the successful application of the concept and the realization of the potential of EAs.Publicationtype: Doctoral Thesis70 36 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimierung von Containertransporten im Hafenhinterland per LKW unter Berücksichtigung von Kooperationsmöglichkeiten(2024); The growth in container transportation worldwide in the past is a major challenge for players in the maritime supply chain regarding empty container logistics. The highest proportion of costs in the maritime supply chain arises from transportation in the port hinterland. Truck carriers are exposed to intense competition. Lack of economies of scale, low margins and service interchangeability require new solutions to strengthen their economic position. Here, in the scientific community the concept of horizontal collaboration is discussed, in which competitors exchange customer orders in a profit-maximizing manner. The aim of horizontal collaboration is not only to increase efficiency and profit for all parties involved, but also to establish it in a fair and stable manner in the long run. An interview study among truck carriers in Hamburg shows that the perception of the market is decisive for the willingness to collaborate. Those carriers who are proactive towards collaboration, prefer to share their customer orders only with selected trustworthy competitors. Furthermore, the academic literature supports the need for monetary and non-monetary benefits of collaboration to be fairly distributed among participants. Based on a literature review and an interview study, a mathematical model is developed and evaluated using two real-world case studies from the Hamburg port hinterland. This model makes a significant contribution to research, as it is the first to consider the aspects of trust groups, compensation payments and fairness mechanisms simultaneously. The application of the model shows that the profit rises with the size of the trust group. This is already the case for two collaborating carriers that form a trust group. It must be considered that own customer orders should be made available for sharing with the trust group. An evaluation regarding fuel consumption shows that avoiding empty container trips and empty trips also reduces CO2 emissions. The results also show that week-based fairness mechanisms achieve a higher profit increase compared to day-based fairness mechanisms. As a fundamental result it should be emphasized that a simultaneous application of profit- and customer order-based fairness mechanisms meets the aim of achieving a fair and long-term stable collaboration.Publicationtype: Doctoral Thesis69 178 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Revenue Management Ansätze für die Auftragsannahme in der Make-to-Order Produktion unter Berücksichtigung von Kundenwertigkeiten(2022); More and more manufacturing companies start production only when an order has been accepted and hence, make use of the make-to-order principle. However, due to limited production capacity, not every order can be accepted. The order acceptance should pursue the usually competing objectives of maximizing profit and, in particular, providing good service to the most important customers. In this dissertation, different revenue management approaches for the order acceptance are developed and analyzed considering both objectives. It can be shown that the developed revenue management strategies work successfully and are able to establish a good trade-off between the competing objectives.Publicationtype: Doctoral Thesis177 908 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimierung geschlossener Wertschöpfungskreisläufe bei beschränkten Kapazitäten(2021-04-11); Nowadays, manufacturing companies are faced with the trade-off between cost minimization through mass production of standardized products and the production of individualized products at high costs. Flexible mass production with modularly designed products, component commonality and order-related production should be the solution to this dilemma. In addition, manufacturing companies are encouraged by social and legal requirements, but also for economic reasons, to take back their used products and remanufacture them. Products with a modular design are suitable for remanufacturing. In this work, a closed-loop supply chain with remanufacturing is examined: Products are returned by customers after use and can be processed in such a way that the components they contain are as good as new and used instead of externally procured components for the order-related manufacture of as-new modular products. Subsequently, a mathematical model for planning this closed-loop supply chain is developed. First, supply chains with reverse product flows are systematically analyzed in order to work out the special planning requirements and thus specifications for the mathematical modeling of the decision problem examined in this work. Quantitative methods for decision support are presented. However, these methods are not suitable for the decision problem of this work because they neglect special planning requirements in the modeling. The facility location problem is one such method; this model and the planning of supply chains using this model are discussed critically. A facility location problem for planning a closed-loop supply chain from the literature is corrected and solved for an example from the copier industry. The solutions show which problems arise from the inadequate mathematical mapping. Building on this knowledge the facility location problem will be expanded step by step. This procedure shows which new findings and improvements can be achieved through the further developed modeling of the decision problem. First of all, the facility location problem is expanded to include production planning with remanufacturing. The solutions for the example from the copier industry show that the mutual dependencies between location, transport and production planning in the supply chain are recorded. In addition, supplier locations and quantities are now considered in the planning. Then the modeling approach is expanded to include (volume) capacity planning and divided into a multi-period planning horizon. Now, the capacity is optimally determined together with the locations as well as the transport, procurement and processing quantities. The solutions prove that now high overcapacities are prevented and the relationship between transport and storage quantities is mapped with site capacities. Furthermore, the influence of product life cycles, customer usage duration of products and product design can now be examined. It can also be observed that the redistribution of production input is optimal under certain conditions. Since production with remanufacturing is labor-intensive, workforce planning must also be included in the modeling. This means that wage costs, processing times and the working hours available at the location are taken into account in the optimization. This planning is further improved by a differentiated modeling of the decision times. This results in a mathematical model that plans the location, capacity, transport, production and workforce of the closed-loop supply chain combined with their respective medium and long-term decision points. In this way, the influence of seasonally fluctuating demand on the supply chain, in particular on capacities, can be examined. With this detailed modeling, the capacity requirement can be determined more precisely and the recording of costs compared to the facility location problem is improved. Consequently, a detailed mathematical mapping of the decision problem is required so that recommendations for economically reasonable measures result.Publicationtype: Doctoral Thesis973 1527 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Entscheidungsfindung in der humanitären Logistik - Ein multikriterielles Transshipmentmodell zur Allokation von Hilfsgütern in laufenden Hilfsaktionen(2016-07-06); Humanitarian relief operations rarely proceed smoothly and disruptions as, e.g., the outbreak of an epidemic or aftershocks, are common. Such situations are known as overlapping disasters. Relief organizations have to deal with the disruptions while at the same time the ongoing relief operation has to proceed. As future developments are uncertain, the aim cannot be to determine a unique optimal solution. Rather, various scenarios are formulated, representing possible developments of the situation. A multi-objective transshipment model is formulated to find efficient allocations of relief items for different scenarios. The model mHumLog is solved by two solution methods both considering uncertainties about future developments. Different indicators are developed for evaluating the scenarios in order to find appropriate decision rules to support the aid worker in allocating relief items.Publicationtype: Doctoral Thesis1038 1967