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Item type:Publication, Access status: with files , Analyse und Optimierung von Suchvorgängen in der industriellen Produktion(2023); In industrial production, search processes appear whenever material or information is needed. Although searching is a fundamental activity within production processes, existing models within production management are not capable of analyzing search processes. This work presents an approach for modeling industrial search processes and describes an analysis procedure for evaluating search efforts in production. In addition, an improvement procedure for systematically deriving measures to reduce search efforts is described. The entire method was successfully applied and evaluated in a low-volume, high-variance production environment.Publicationtype: Doctoral Thesis71 196 - 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 Thesis175 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 , Modellierung von Unsicherheiten in der Planung der UnikatproduktionThis thesis develops a procedure for the analysis of uncertainties in the planning of the one-of-a-kind production. The central element is the modelling of the uncertain work contents and their connection with the logistic objectives. The analysis includes methods for the collection and evaluation of the uncertain work contents. The subsequent configuration of work planning as well as the production planning and control includes measures to ensure that the logistical objectives are achieved.Publicationtype: Doctoral Thesis482 2099 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Ein Bewertungsansatz zur Analyse von Zustandsmanagementsystemen in Verkehrsflugzeugen unter Berücksichtigung neuer InstandhaltungskonzepteThis research study deals with the technology assessment of health management systems and condition-based/predictive maintenance concepts for future commercial aircraft. A model for a discrete-event-simulation of aircraft operation, failure and maintenance events and the impacts of diagnostic and prognostic technologies in the aircraft life cycle with the integration of an optimization approach for the dynamic maintenance planning is developed. For the evaluation of the economic benefit from an operator's perspective, a cost-benefit analysis based on the discounted cash flow method is applied. In an application case, the operational and economic potential of health management systems is demonstrated by the example of a short/medium-haul aircraft.Publicationtype: Doctoral Thesis726 3575 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Analyse und Verbesserung der Arbeitsproduktivität in der Unikatproduktion(2017); This thesis develops a method for the analysis and improvement of labor productivi-ty in one-of-a-kind productions. The central element is the modeling of the paid working time with activities and objects. The classification into phases of a generic work cycle allows repeatable productivity gains. A multi-dimensional work sam-pling is the standard for the data acquisition. Based on the results, improvement ac-tivities can be systematically selected.Publicationtype: Doctoral Thesis1736 6730 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Simulation-based evaluation of operation and maintenance logistics concepts for offshore wind power plantsA modular simulation model for the operation of offshore wind power plants has been developed. The model is able to represent offshore-based and onshore-based logistics concepts. The output is logistics and opportunity costs (revenue losses). Multiple simulation experiments have been conducted on different logistics concepts and offshore wind power plant scenarios. The investigation shows that for most German offshore wind power plants an onshore-based logistics concept is most cost-efficient. The success of onshore-based concepts is related to high additional costs of offshore-based concepts. A combination of concepts leads to the best cost efficiency. The developed model distinguishes itself from other approaches by the ability for monthly analysis.Publicationtype: Doctoral Thesis803 1308 - 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