Hierarchical planning in a single stage system

Single stage systems with high set-up times and high utilization levels occur in flow process industries. In this paper a two-tiered hierarchical model is developed for such a system. At the top level, the optimal value of the control parameters is determined, while the operational scheduling function is performed at the bottom level. The conceptual aggregation approach used in this model is compared to the aggregation approach used in classical hierarchical approaches

Equalization of run-out times under high demand and lost sales : technical note

No abstract

Cost, carbon emissions and modal shift in intermodal network design decisions

Intermodal transportation is often presented as an efficient solution for reducing carbon emissions without compromising economic growth. In this article, we present a new intermodal network design model in which both the terminal location and the allocation between direct truck transportation and intermodal transportation are optimized. This model allows for studying the dynamics of intermodal transportation solutions in the context of hinterland networks from a cost, carbon emissions and modal shift perspective. We show that maximizing the modal shift is harmful for both cost and carbon emissions and that there is a carbon optimal level of modal shift. We also show that even if transportation cost and carbon emissions share the same structure, these two objectives lead to different solutions and that the terminal is located closer to the port when optimizing cost and further away when optimizing carbon emissions. The model also allows for studying the tradeoff between distance and volume, the impact of using aggregated models for estimating train transportation cost and carbon emissions as well as the potential policy measures that enable aligning cost and carbon emissions

Action variety of planners : cognitive load and requisite variety

The complexity of planning tasks have increased over the past decade. There is relatively poor understanding what the implications are of increased task complexity in planning and scheduling operations. Previous work in the behavorial sciences have investigated the concept of cognitive load, addressing both task complecity and task workload or stress, and have concluded that decision makers tend to resort to routine action and reduce the variety in their actions with increasing complexity and workload. Alternatively, control theory suggests that a higher variety of actions is needed to deal with more complex problems. In this paper, we investigate the effects of task complexity in a chemical plant on the variety of actions deployed by the planners. The single work center resource structure and the availability of actual planning data from an ERP system allows us to both use field data and study a situation which is simple enough to measure the main effect. Our results suggest that increased task complexity without time pressure does indeed lead to increased action variety deployed by the planners

Ocean container transport : an underestimated and critical link in global supply chain performance

With supply chains distributed across global markets, ocean container transport now is a critical element of any such supply chain. We identify key characteristics of ocean container transport from a supply chain perspective. We find that unlike continental (road) transport, service offerings tend to be consolidated in few service providers, and a strong focus exists on maximization of capital intensive resources. Based on the characteristics of the ocean container transport supply chain, we list a number of highly relevant and challenging research areas and associated questions

Inter-company supply chain planning : extending the current modeling perspective

Many companies are implementing new mechanisms to better manage operations across units in a supply chain. Both the operations management literature and the accounting literature are investigating such inter-organizational developments. Since supply chain planning (SCP) typically started across several units within the domain of a single company, the models that have been developed in inventory theory assume a single company perspective. SCP from a centralized perspective optimizes objectives at the level of the total chain. However, it is mainstream thought nowadays in the operations management literature that the planning function should focus as much as possible on the entire supply chain rather than on a single unit in the supply chain. Consequently, SCP across independent companies has seen some attempts in practice, although inventory models have not been formulated so far. The accounting literature has started to examine the conditions under which information exchange mechanisms and other elements of SCP are beneficial to each individual company in the supply chain. The present paper builds on this perspective of the individual units' objectives. Each unit will often be part of different supply chains, and we investigate how decisions made by the SCP functions of those different supply chains may interfere at the level of the unit. These planning decisions may not be in that unit's best interest, which would prevent independent companies from engaging in SCP. This paper introduces two new concepts to describe and support SCP across independent companies: outsourced SCP and between-supply-chain coordination