Research Project: Data-driven method based on a process mining approach for Automated Digital Twin generation, operations, and maintenance in circular value chains
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Contributors
Funders
ID
EC.00171
Authors
Karaesmen, Fikri
Faculty Member
Publications
The digital twin synchronization problem: framework, formulations, and analysis
(Taylor & Francis Inc, 2023) Tan, Barış; Matta, Andrea; Department of Business Administration; Yes; College of Administrative Sciences and Economics
As the adoption of digital twins increases steadily, it is necessary to determine how to operate them most effectively and efficiently. In this article, the digital twin synchronization problem is introduced and defined formally. Frequent synchronizations would increase cost and data traffic congestion, whereas infrequent synchronizations would increase the bias of the predictions and yield wrong decisions. This work defines the synchronization problem variants in different contexts. To discuss the problem and its solution, the problem of determining when to synchronize an unreliable production system with its digital twin to minimize the average synchronization and bias costs is formulated and analyzed analytically. The state-independent, state-dependent, and full-information solutions have been determined by using a stochastic model of the system. Solving the synchronization problem using simulation is discussed, and an approximate policy is proposed. Our results show that the performance of the state-dependent policy is close to the optimal solution that can be obtained with full information and significantly better than the performance of the state-independent policy. Furthermore, the approximate periodic state-dependent policy yields near-optimal results. To operate digital twins more effectively, the digital twin synchronization problem must be considered and solved to determine the optimal synchronization policy.
Green Gateways: a concept for decisions in Circular-Oriented Economies
(Elsevier B.V., 2024) Tan, Barış; Frigerio, Nicla; Matta, Andrea; Department of Business Administration; Yes; College of Administrative Sciences and Economics
Industrial technologies have evolved towards circular-oriented manufacturing. New approaches in the management of production systems are needed to guarantee the success of such a circular approach. This paper identifies three research questions related to the complexities of decision-making within CEs and defines the concept of Green Gateways in the circular economy. A Green Gateway is a type of decision that supports to realizing the full potential of products and materials. Indeed, the potential value of products and materials must be assessed and leveraged and the concept of Green Gateway will be useful to identify common decisions and to define a common framework in the future. The integration of digital information and digital twins of products, processes, and circular value and supply chains emerges as a key factor in guiding decision-makers effectively, especially for Green Gateways where adequate information, tools and methods must be used to manage value retention options, product flows, production and pricing decisions jointly with the multiple objectives of profitability and sustainability. Additionally, this paper explores specific examples of circular economy use cases, drawing attention to their similarities and highlighting key insights. © 2024 The Author(s).
Purchasing and remanufacturing decisions with different quality returned material and finished goods
(Taylor and Francis, 2025) Karaesmen, Fikri; Karabağ, Oktay; Tan, Barış; Department of Industrial Engineering; Yes; College of Engineering
To transition from a linear to a circular value chain, an effective refurbishment policy is crucial to preserve material value and functionality at the end of a product's life-cycle. This study examines a refurbisher that processes first- and second-quality returned materials to produce first- and second-quality products in a make-to-stock system. The refurbisher makes purchasing decisions for the returned materials and determines whether to refurbish or remain idle, and if refurbishing, how to convert them into finished goods of varying quality. There are five refurbishment decisions (converting first-quality to first- or second-quality, second-quality to first- or second-quality, or no production) and two purchasing decisions for the materials. With production and arrival times modelled as exponential random variables, the optimal control problem is formulated as a Markovian Decision Process, using a long-run average profit criterion to identify optimal decisions. A linear programming approach is employed for numerical optimisation. Results show that the most profitable option based solely on sales prices, purchasing, and conversion costs may not be optimal. Instead, the optimal policy is influenced by per-unit profit differences, returned material availability, demand rates, and production times across various refurbishment scenarios.
Optimizing production and remanufacturing decisions for make-to-stock hybrid manufacturing systems using real-time information on products in use
(Taylor and Francis, 2025) Karaesmen, Fikri; Karabağ, Oktay; Tan, Barış; Department of Industrial Engineering; Yes; College of Engineering
This study presents an analytical framework for make-to-stock hybrid manufacturing systems that use both virgin and returned materials to produce a single product. The system is modelled as a Markov Decision Process, and a linear programming approach is used to determine optimal decisions on when to produce, which material to use, and whether to remanufacture or dispose of returned items. A key feature of the model is the inclusion of real-time tracking information on products in use within such a circular system, which supports informed and timely decision-making. We conduct a comparative numerical analysis between the optimal policy and a simplified one that omits orbit information. Our results show that excluding orbit information leads to an average profit loss of 2.21%, with losses reaching up to 11.18% in some settings, quantifying the economic impact of tracking capabilities in closed-loop systems. We also examine the effect of regulatory minimums that require a portion of production to use returned materials. While such policies support sustainability goals, they may reduce profitability when return rates are low or holding costs are high. We believe these findings offer practical guidance for firms seeking to balance profitability, regulatory compliance, and operational simplicity in circular manufacturing environments. © 2025 Elsevier B.V., All rights reserved.
