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Item type:Publication, Access status: with files , The key to improving the trade-off between service and inventory levels in make-to-stock production: sequencing and capacity controlSafety stocks play an important role in make-to-stock production, since they ensure supply to customers despite uncertainties in production and demand. A large literature exists on safety stock calculations, but it typically assumes exogenous stationary replenishment times. In most real-world settings, capacity is a constraint leading to non-stationary replenishment times that are under the control of management. In response, we design a new production planning and control approach for make-to-stock production based on cumulative quantity logic and show how companies can use sequencing and capacity control based on current demand to improve customer supply and to reduce safety stocks. Results from discrete event simulations highlight the potential of the new approach and indicate that the proposed manufacturing control reacts robustly against wrongly set planned demand rates. This contributes to theory, while the comparatively low information processing requirements and robustness of the approach make it an important potential solution for practice.Publicationtype: Journal Article17 10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Digital assistance systems for just-in-sequence packing: key enablers for productive shipyard assembly(Springer, 2026-09-18); ; ; ; Assembly personnel in one-of-a-kind shipbuilding dedicate only a small proportion of their on-site time to value-adding activities, with non-productive tasks consuming up to 78% of their working hours. Considerable effort is expended on material procurement, information retrieval, and preparation of work sites. In addition, evolving customer requirements and internal planning deviations lead to frequent design changes in the production phase, resulting in substantial rework and elevated scrap rates. This is particularly evident for pipes, fittings, and related accessories, which are integral to numerous onboard systems throughout the vessel. Coordinating their delivery through traditional sequential scheduling results in redundant handling due to time-consuming retrieval processes for pre-manufactured parts by suppliers, and complex on-site material provision by shipyard logistics. A promising approach to overcome these challenges is to schedule frequent, small-batch deliveries in line with construction progress. While synchronizing supplier production and delivery with the assembly progress has proven to be an effective solution in automotive serial production, its application in one-of-a-kind shipbuilding is severely limited by the poor availability and accessibility of up-to-date information. To bridge this gap, this paper examines the picking and packing of installation-ready units by suppliers through the systematic use of prototype digital assistance systems integrated with a consistent database. Ultimately, this approach aims to significantly enhance the productivity of shipyard assembly workers and accelerate overall ship delivery schedules.Publicationtype: Conference Paper49 6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Evaluating the robustness of production planning and control proceduresProduction Planning and Control (PPC) procedures are very important for a stable production performance but are traditionally evaluated under the assumption of good input data quality. This reliance creates a vulnerability, as industrial environments frequently suffer from high uncertainties and systematic parameter biases that cause continuous, cumulative deviations from logistical target achievement. To address this research gap, this paper introduces a three-step evaluation framework to assess the structural robustness of PPC procedures. The proposed framework combines qualitative analysis, empirical stress testing via discrete event simulation, and mathematically sound analytical modelling using the throughput diagram. The methodology is successfully applied to evaluate the Planned Output Control (POC) procedure. The results show mathematically and empirically that closed-loop control architectures possess a fundamental advantage over open-loop systems in autonomously mitigating parameter drift. This framework enables researchers and practitioners to systematically benchmark and design robust PPC procedures prior to industrial implementation.Publicationtype: Conference Paper32 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Logistic operating curves for closed queueing systems: Enhancing container terminal productivity through shared queuesContainer terminals are vital nodes in global supply chains, linking maritime and land transport. Terminal operators face the critical challenge of balancing vessel handling times and operational costs – a conflict of objectives. Building on our previous work that introduced an engineering-oriented approach using Logistic Operating Curves and an extended Kingman approximation for ship-to-shore crane productivity under fixed vehicle allocations, this paper advances the model to accommodate shared vehicle queues. In such configurations, terminal trucks serve multiple ship-to-shore cranes from a common pool, preserving the closed queueing system characteristics inherent to terminal operations.Publicationtype: Conference Paper31 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Analysing sequencing in make-to-order companiesSufficient order sequencing configuration and implementation are key to achieving high schedule reliability and, consequently, customer satisfaction in make-to-order companies. This paper proposes a multi-method analysis approach to evaluate sequencing in make-to-order production. The approach consists of two phases: (1) data collection, including interviews, an order-level feedback data analysis, the value stream analysis for make-to-order companies, and process observations, and (2) an interpretative analysis to identify configuration and implementation deficits. As part of the feedback data analysis, a rank-based correlation analysis is introduced and validated using simulation data, providing visually accessible insights into sequencing implementation through characteristic correlation patterns. The multi-method analysis is validated in a case study, demonstrating its practical applicability and the benefits of integrating multiple analytical methods.Publicationtype: Conference Paper30 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Assignment of orders in horizontal transport at sea-port container terminals(Springer Nature Switzerland, 2026-07-09); ; ; ; Quay cranes (QCs) represent the primary operational bottleneck at seaport container terminals due to their high capital intensity and role as critical nodes in global supply chains. Their productivity is strictly dependent on the efficient coordination of horizontal transport, specifically the assignment of transport orders to terminal trucks (TTs). While many terminals still rely on fixed TT-to-QC assignments, this approach often lacks the flexibility to handle disruptions and fluctuating workloads. This paper investigates the potential of a flexible, multi-criteria assignment procedure – considering work-in-process, travel distances, and QC waiting times – compared to traditional fixed assignments. The performance is evaluated using Logistic Operating Curves (LOCs), which map QC productivity against the number of deployed TTs. The results demonstrate that flexible assignment significantly outperforms fixed assignment in underload scenarios (low TT availability or high travel speeds), showing productivity gains of up to 17.85% during vehicle disruptions. However, this advantage diminishes as transport capacity increases. In high-utilization overload zones, the flexible method falls slightly below fixed assignment performance. This discrepancy is attributed to the timing of order assignment; making decisions when a previous task is completed, rather than at the last possible second, limits the system’s ability to react to real-time fluctuations. The study concludes that flexible assignment increases robustness during transport shortages, but achieving theoretical productivity benchmarks requires shifting toward late-assignment strategies.Publicationtype: Conference Paper74 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , How digital assistance systems improve the analysis of industrial assembly processesThe analysis of work processes in industrial assembly is essential for improving ergonomics and productivity. Digital assistance systems that automatically capture and analyse data from work processes using motion capture systems are showing great potential. This reduces the effort involved and makes it possible to perform different analyses simultaneously. We have developed such an assistance system and applied it both in a laboratory environment and in industry to assess its potential benefits. The results show that the digital assistance system can be used to quickly and effectively improve the ergonomics and productivity of assembly processes, both in early planning phases and during ongoing production.Publicationtype: Journal Article37 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Kennzahlen und Verbesserung von ProduktionssystemenKennzahlen ermöglichen die objektive Bewertung und gezielte Verbesserung von Produktionssystemen, Arbeitsbereichen und gesamten Unternehmen. Ihre Funktion erstreckt sich nicht ausschließlich auf die Leistungsbewertung, sondern umfasst auch die Identifikation von Einflussfaktoren. Als objektive Maßstäbe ermöglichen sie eine fundierte Analyse und unterstützen Unternehmen bei der gezielten Verbesserung ihrer Prozesse. Folgender Beitrag veranschaulicht anhand der Kennzahlen Termintreue und Produktivität, wie eine systematische Verbesserung von Produktionssystemen erfolgen kann. Dazu werden die relevanten Kennzahlen und ihre Einflussgrößen definiert, Methoden zur Datenerhebung erläutert, Analyseansätze vorgestellt und konkrete Optimierungsmaßnahmen aufgezeigt.Publicationtype: Book Part73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Modelling of logistics objectives at the sea side of container terminalsIn the context of the expanding global economy, the significance of transport chains has been increasingly recognized, with container terminals assuming a pivotal role within these networks. The competitive environment has led to pressure on these terminals, giving rise to a conflict of logistical objectives such as short vessel handling times and minimized handling costs. Previous attempts to address this issue, including simulation studies and deterministic mathematical models, have yet to be effectively implemented in practical settings due to their sensitivity to parameters and inherent complexity. This study proposes a novel engineering-centred approach utilizing Logistic Operating Curves to model terminal objectives, with a particular emphasis on quayside operations such as container handling by ship-to-shore cranes and terminal trucks. The paper explores the derivation of ideal and real Logistic Operating Curves for ship-to-shore cranes. Therefore, the well-known Kingman equation is extended to map the special characteristics of a closed queueing system. The simulation experiments conducted demonstrate that the proposed model provides sufficient accuracy in predicting mean productivities. The study concludes that the Logistic Operating Curves framework serves as an effective, understandable and adaptable method for improving terminal operations and highlights areas for further research.Publicationtype: Conference Paper118 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Concept of manufacturing control for a workstation with sequence-dependent setup times in a make-to-stock productionSequence-dependent setup times pose a challenge for a make-to-stock production. If companies apply setup-optimised sequencing to reduce setup efforts, varying replenishment times of the finished goods warehouse will increase the required safety inventories of the products. This publication presents a comprehensive manufacturing control concept for workstations with sequence-dependent setup times in make-to-stock production. The manufacturing control concept aims to effectively control the workstation and finished goods inventory, thereby enhancing the achievement of logistical objectives. The proposed concept integrates three relevant tasks of manufacturing control: order generation, capacity control, and sequencing. Cumulative Production Figures serve as a superordinate procedure, facilitating order generation and capacity control, while cyclical sequencing reduces setup efforts. Simulation experiments validate and evaluate the manufacturing control concept, demonstrating its effectiveness in managing setup efforts while limiting the negative impacts on required safety inventories. The results align with theoretical modeling and show potential for practical application in companies with make-to-stock production.Publicationtype: Conference Paper50