@inproceedings{HaimerlTschernitzSchilleretal., author = {Haimerl, Simon and Tschernitz, Christoph and Schiller, Tobias and Weig, Christoph and Briem, Ulrich and Galka, Stefan}, title = {Development of a Simulation Framework for Urban Ropeway Systems and Analysis of the Planned Ropeway Network in Regensburg, Germany}, series = {Proceedings of the 2022 Winter Simulation Conference (WSC), 11-14 Dec. 2022, Singapore}, booktitle = {Proceedings of the 2022 Winter Simulation Conference (WSC), 11-14 Dec. 2022, Singapore}, publisher = {IEEE}, isbn = {978-1-6654-7661-4}, doi = {10.1109/WSC57314.2022.10015510}, pages = {1413 -- 1424}, abstract = {To evaluate the performance of a ropeway in an urban environment, simulations of the dynamic passenger transport characteristics are required. Therefore, a modular simulation model for urban ropeway networks was developed, which can be flexibly adapted to any city and passenger volume. This simulation model was used to analyze the ropeway network concept of the German city Regensburg and to determine the expected operating conditions. The passenger volume, different types of persons, their occurrence probability and their destination distribution is depending on the location and daytime and can be defined for each individual station. In an initial analysis, the number of passengers currently occurring in bus traffic were projected onto the ropeway network. To enable climate-friendly and efficient operation, different strategies were developed to significantly reduce the number of gondolas. The best fitting strategies resulted in significant cost savings while passenger comfort, as represented by queue time, remained unchanged.}, language = {en} } @article{KlenkGalka, author = {Klenk, Eva Marianne and Galka, Stefan}, title = {Analysis of real-time tour building and scheduling strategies for in-plant milk-run systems with volatile transportation demand}, series = {IFAC - PapersOnLine}, volume = {52}, journal = {IFAC - PapersOnLine}, number = {13}, publisher = {Elsevier}, doi = {10.1016/j.ifacol.2019.11.517}, pages = {2110 -- 2115}, abstract = {In modern manufacturing systems, milk run (MR) systems represent route-based, cyclic material-handling systems that are used widely and enable frequent deliveries of containerized parts in small lot sizes from a central storage area to multiple points of use on the factory floor. Usually, deliveries take place at predetermined, constant time intervals. As in real-world MR systems, the number of containers to deliver in each interval varies in the short term, peaks in the number of deliveries may lead to capacity bottlenecks and late deliveries. In this paper, we develop three alternative strategies to determine starting times of MR cycles in real-time based on the current number of delivery orders in the system aiming to better handle variations in the number of orders. We evaluate the three strategies for different system load scenarios with respect to delivery service levels, order lead times, systems utilization and necessary number of MR trains using a discrete-event simulation model.}, language = {en} } @article{GalkaWappler, author = {Galka, Stefan and Wappler, Mona}, title = {Integration of cash flow management and further aspects of the supply chain management in production system design}, series = {IFAC-PapersOnLine}, volume = {56}, journal = {IFAC-PapersOnLine}, number = {2}, publisher = {IFAC / Elsevier}, doi = {10.1016/j.ifacol.2023.10.1687}, pages = {947 -- 952}, abstract = {One major goal of production system design is to decide on space requirements in the plant. In this phase, detailed information about the supply chain network (e.g. which suppliers deliver which parts) is often unavailable. Nevertheless, typical decisions in supply chain management, like the definition of replenishment processes and quantities or make-or-buy decisions, impact space requirements and the capital investment in raw materials. Therefore, it should be considered in factory and production planning. This research article proposes a simulation approach for a production simulation in which raw material replenishment is integrated to evaluate the capital investment and space requirements for raw materials.}, language = {en} } @book{GalkaFottnerKlenketal., author = {Galka, Stefan and Fottner, Johannes and Klenk, Eva Marianne and Habenicht, Sebastian and Meinhardt, Ingolf and Schmidt, Thorsten}, title = {Planung von innerbetrieblichen Transportsystemen}, volume = {2022}, edition = {1. Auflage}, publisher = {Springer Vieweg}, address = {Berlin, Heidelberg}, isbn = {978-3-662-63972-6}, doi = {10.1007/978-3-662-63973-3}, pages = {231}, abstract = {Dieses Buch beschreibt bew{\"a}hrte, praxistaugliche Methoden zur Planung innerbetrieblicher Transportsysteme. Der Fokus liegt auf den wesentlichen Systemen und F{\"o}rderfahrzeugen, die derzeit in der Industrie eingesetzt werden: Gabelstapler, fahrerlose Transportfahrzeuge, Routenz{\"u}ge und Elektroh{\"a}ngebahnen. Neben einer Beschreibung relevanter Systemelemente und Gestaltungsm{\"o}glichkeiten liefert das Buch Empfehlungen zur Auswahl eines geeigneten Systems entsprechend der individuellen Anforderungen. Planungsschritte von der Erhebung von Plandaten bis zur Umsetzung werden vorgestellt. Methoden, die bei Planungsentscheidungen wie der Bestimmung der Anzahl ben{\"o}tigter Fahrzeuge helfen, sind detailliert beschrieben; ihre Anwendung wird anhand von Fallbeispielen demonstriert. Do's and Dont's, basierend auf Erfahrungen von Praktikern und Wissenschaftlern, tragen dazu bei, Planungsfehler zu vermeiden. Das Buch wendet sich an Planer und Betreiber derartiger Systeme, Studierende einschl{\"a}giger Studienf{\"a}cher bekommen einen vertieften Einblick in die Umsetzung der Methoden.}, subject = {Intralogistik}, language = {de} } @inproceedings{GalkaSchmid, author = {Galka, Stefan and Schmid, Florian}, title = {Initialization of Simulation-Based Digital Twins for Internal Transport Systems}, series = {IFAC-PapersOnLine}, volume = {58}, booktitle = {IFAC-PapersOnLine}, number = {19}, editor = {Schlund, Sebastian and Ansari, Fazel}, address = {Wien}, organization = {International Federation of Automatic Control (IFAC)}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2024.09.127}, pages = {1084 -- 1089}, abstract = {To support operational decisions using simulation-based digital twins, it is crucial to synchronize the simulation model quickly and accurately with the load state in the real system. This minimizes the typical transient behavior of material flow simulations to a short period of time. This paper presents a concept for initializing a simulation model using the example of a distribution center that uses SAP EWM as a warehouse management system. As part of a study, the influence of the presented initialization concept on the simulation models' transient behavior is investigated. The simulation model used as a reference is in an 'empty' load state at the beginning of the simulation. The study results indicate that the proposed approach can significantly shorten the transient behavior.}, language = {en} } @inproceedings{Galka, author = {Galka, Stefan}, title = {Reducing Transient Behavior in Simulation-Based Digital Twins: A Novel Initialization Approach for Order Picking Systems}, series = {2024 Winter Simulation Conference (WSC), 15-18 December 2024, Orlando, FL, USA}, booktitle = {2024 Winter Simulation Conference (WSC), 15-18 December 2024, Orlando, FL, USA}, publisher = {IEEE}, isbn = {979-8-3315-3420-2}, doi = {10.1109/WSC63780.2024.10838961}, pages = {1434 -- 1445}, abstract = {In the context of facilitating operational decision-making through simulation-based digital twins, precise and expeditious synchronization of simulation models with real-system load states is paramount. Such synchronization serves to attenuate the typical transient behavior observed in material flow simulation, confining it to a brief temporal window. This paper delineates a novel conceptual framework for initializing simulation models, illustrated through an exemplar of an order picking system integrated with SAP Extended Warehouse Management as its warehouse and operation management system. Through empirical inquiry, the ramifications of the proposed initialization framework on simulation model transient behavior are scrutinized. Notably, the reference simulation model commences in a state of 'empty' load. The findings of this study evince that the proposed approach yields a significant improvement in transient behavior.}, language = {en} } @inproceedings{SchuheggerArmbrusterGalka, author = {Schuhegger, Lukas and Armbruster, Thomas and Galka, Stefan}, title = {Factory Data Model for Planning Variant Sequences, Expansion Stages and Reconfigurations}, series = {IFAC-PapersOnLine}, volume = {56}, booktitle = {IFAC-PapersOnLine}, number = {2}, publisher = {IFAC / Elsevier}, doi = {10.1016/j.ifacol.2023.10.1573}, pages = {227 -- 232}, abstract = {A factory has to adapt to a future production program and increasing volumes. The planning of new factories must therefore already take expansion stages and reconfigurations into account. This leads to an increase in the complexity of planning, as different variants have to be planned and put into a chronologically reasonable and cost-optimized sequence. A factory data model that covers expansion stages manages the planning data amount and reduces complexity. Based on existing models from the literature, a factory data model was developed and modeled in the Unified Modeling Language standard. The factory data model shows which classes are interdependent and how planning results are stored reusable for other variants. An example is used to explain the developed factory data model and highlighting its advantages. The aim is to enable factory planners to document variant sequences and expansion stages in a comprehensible way, which supports the interdisciplinarity of factory planning projects.}, language = {en} } @inproceedings{RolfReggelinLangetal., author = {Rolf, Benjamin and Reggelin, Tobias and Lang, Sebastian and Galka, Stefan}, title = {Developing a Decision Support System for Integrated Decision-Making in Purchasing and Scheduling under Lead Time Uncertainty}, series = {Proceedings of the 55th Hawaii International Conference on System Sciences (HICSS55): January 3-7, 2022, Maui, Hawaii, USA}, volume = {2022}, booktitle = {Proceedings of the 55th Hawaii International Conference on System Sciences (HICSS55): January 3-7, 2022, Maui, Hawaii, USA}, doi = {10.24251/HICSS.2022.247}, pages = {1964 -- 1973}, abstract = {Decision-making in supply chain management is complex because of the relations between planning tasks from different stages and planning levels. Uncertainties such as unpredictable supplier lead times and supply chain disruptions further complicate decision-making. Considering the case study of a company in printed circuit board assembly, a three-level concept is proposed that includes a decision support system. The global single-source supply network is characterized by highly variable lead times. Hence, the company maintains high inventory levels to prevent running out of stock. The decision support system considers the purchasing and scheduling decision problems in an integrated way. The prototypical implementation of the purchasing algorithm uses a genetic algorithm that recommends reorder days and order quantities using a simulation model. In addition, it evaluates the risks of the recommended solution by calculating the probability of stockouts for each order cycle.}, language = {en} } @inproceedings{KaukeFottnerGalka, author = {Kauke, Dirk and Fottner, Johannes and Galka, Stefan}, title = {Digital Twins in Order Picking Systems for Operational Decision Support}, series = {Proceedings of the 54th Hawaii International Conference on System Sciences (HICSS): 2021 Hawaii, USA}, booktitle = {Proceedings of the 54th Hawaii International Conference on System Sciences (HICSS): 2021 Hawaii, USA}, publisher = {University of Hawai'i at Manoa Hamilton Library}, address = {Honolulu, HI}, isbn = {978-0-9981331-4-0}, doi = {10.24251/HICSS.2021.200}, pages = {1655 -- 1664}, abstract = {Digital twins are arousing great interest in both science and industry. There are a large number of papers that demonstrate and evaluate the potential of Digital Twins in different application areas. However, it must be noted that there is still no uniform definition of Digital Twins. This paper first examines the concept of Digital Twins and highlight how they differ in level, compared with other digital models. The focus of this paper lies in the conceptual development of a digital twin in order picking systems. The described approach in the paper aims at supporting the operational control in order picking systems. Both the architectural structure and the functions, e.g. the simulation, are described in detail. Overall, this thesis shows the benefits of Digital Twins. However, some functional extensions are still needed before the full potential can be achieved.}, language = {en} } @incollection{FottnerGalkaHabenichtetal., author = {Fottner, Johannes and Galka, Stefan and Habenicht, Sebastian and Klenk, Eva Marianne and Meinhardt, Ingolf and Schmidt, Thorsten}, title = {Gestaltungsprinzipien f{\"u}r innerbetriebliche Fahrzeugsysteme}, series = {Planung von innerbetrieblichen Transportsystemen}, booktitle = {Planung von innerbetrieblichen Transportsystemen}, editor = {Fottner, Johannes and Galka, Stefan and Habenicht, Sebastian and Klenk, Eva Marianne and Meinhardt, Ingolf and Schmidt, Thorsten}, edition = {First Online: 07 May 2022}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-662-63972-6}, doi = {10.1007/978-3-662-63973-3_3}, pages = {67 -- 76}, abstract = {Bei der Planung von innerbetrieblichen Transportsystemen besteht die Aufgabe darin, Transportsysteme so zu gestalten und zu dimensionieren, dass Unternehmensziele unter Ber{\"u}cksichtigung gegebener Rahmenbedingungen m{\"o}glichst ideal erf{\"u}llt werden. Ob ein geplantes System schlussendlich den an die L{\"o}sung gestellten Zielen gerecht wird und wie gut es "funktioniert", ergibt sich aus dem Zusammenspiel der in Kap. 2 beschriebenen Systemelemente. Da sich Ziele und Rahmenbedingungen je nach konkretem Einsatzfall unterscheiden und sich daraus unterschiedliche Anforderungen an Transportsysteme ergeben, m{\"u}ssen die Systembausteine in geeigneter Kombination ausgestaltet und dimensioniert werden. Ans{\"a}tze daf{\"u}r werden in Kap. 5 ausf{\"u}hrlich vorgestellt.}, language = {de} } @book{LiebKlenkGalkaetal., author = {Lieb, Christian and Klenk, Eva Marianne and Galka, Stefan and Keuntje, Christopher}, title = {Einsatz von Routenzugsystemen zur Produktionsversorgung : Studie zu Planung Steuerung und Betrieb}, publisher = {fml - Lehrstuhl f{\"u}r F{\"o}rdertechnik Materialfluß Logistik Technische Universit{\"a}t M{\"u}nchen}, address = {Garching b. M{\"u}nchen}, isbn = {978-3-941702-79-0}, language = {de} } @article{Galka, author = {Galka, Stefan}, title = {Tipps zur Absicherung der Investitionsentscheidung in ein Autostore-System}, series = {F{\"o}rdern + Heben}, journal = {F{\"o}rdern + Heben}, number = {1-2}, publisher = {Vereinigte Fachverlage GmbH}, address = {Mainz}, pages = {12 -- 14}, language = {de} } @article{GalkaFollathBross, author = {Galka, Stefan and Follath, Alexander and Bross, Florian}, title = {Vorgehensmodell zur Erstellung Digitaler Zwillinge f{\"u}r Produktion und Logistik}, series = {Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb}, volume = {117}, journal = {Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb}, number = {11}, editor = {Bauer, Wilhelm and Volk, Wolfram and Z{\"a}h, Michael}, publisher = {De Gruyter}, address = {Berlin}, doi = {10.1515/zwf-2022-1127}, pages = {691 -- 696}, abstract = {Der Digitale Zwilling (DZ) ist ein wichtiger Bestandteil der Industrie 4.0 und erm{\"o}glicht Anwendungen wie Predictive Maintenance, virtuelles Prototyping oder die Steuerung von Produktions- und Logistikprozessen. Herausforderungen bei der Entwicklung des Digitalen Zwillings entstehen durch fehlende Struktur und Standards. Mit diesem Beitrag soll ein Vorgehensmodell f{\"u}r die Erstellung eines Digitalen Zwillings im Bereich der Produktion und Logistik aufgezeigt werden. Das Vorgehensmodell hilft bei der Einordnung, f{\"u}r welche Anwendungsf{\"a}lle ein Digitaler Zwilling entwickelt werden kann, welche Schritte bei einer Umsetzung erfolgen m{\"u}ssen, und gibt einen {\"U}berblick {\"u}ber die Voraussetzungen und Komplexit{\"a}t bei der Entwicklung. Das zentrale Element bildet dabei die zielgerichtete Aufbereitung und Analyse der zugrunde liegenden Daten mittels des in der Industrie etablierten Vorgehensmodell CRISP-DM.}, language = {de} }