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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 1969 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Decision making in humanitarian logistics : a multi-objective optimization model for relocating relief goods during disaster recovery operations(2013); Disaster recovery operations rarely proceed smoothly and disruptions often require the redistribution of relief items. Such a redistribution has to be carried out taking into account both the current disruption and the uncertainty regarding possible future incidents in the respective area. As decisions have to be made fast in humanitarian operations, extensive optimization runs cannot be conducted in such a situation. Nevertheless, sensible decisions should be made to ensure an efficient redistribution, considering not only satisfaction of needs but also operational costs, as the budget is usually scarce in the recovery phase of a disaster. In this work, different scenarios are generated and then solved with a multiobjective optimization model to explore possible developments. By evaluating the results of these scenarios, decision rules are identified which can support the decision maker in the actual disaster situation in making fast, but nevertheless well-founded, decisions.Publicationtype: Conference Paper56 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A transshipment model for distribution and inventory relocation under uncertainty in humanitarian operationsThe number of disasters and humanitarian crises which trigger humanitarian operations is ever-expanding. Unforeseen incidents frequently occur in the aftermath of a disaster, when humanitarian organizations are already in action. These incidents can lead to sudden changes in demand. As fast delivery of relief items to the affected regions is crucial, the obvious reaction would be to deliver them from neighbouring regions. Yet, this may incur future shortages in those regions as well. Hence, an integrated relocation and distribution planning approach is required, considering current demand and possible future developments.For this situation, a mixed-integer programming model is developed containing two objectives: minimization of unsatisfied demand and minimization of operational costs. The model is solved by a rolling horizon solution method. To model uncertainty, demand is split into certain demand which is known, and uncertain demand which occurs with a specific probability. Periodically increasing penalty costs are introduced for the unsatisfied certain and uncertain demand. A sensitivity analysis of the penalty costs for unsatisfied uncertain demand is accomplished to study the trade-off between demand satisfaction and logistical costs. The results for an example case show that unsatisfied demand can be significantly reduced, while operational costs increase only slightly.Publicationtype: Journal Article181 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Inventory relocation for overlapping disaster settings in humanitarian operationsThe number and scale of humanitarian operations has significantly increased during the past decades due to the rising number of humanitarian emergencies and natural disasters worldwide. Therefore, the development of appropriate planning methods for optimization of the respective supply chains is constantly growing in importance. A specific problem in the context of humanitarian operations is the supply of relief items to the affected areas after the occurrence of a sudden change in demand or supply, for example, due to an epidemic or to unexpected shortages, during an ongoing humanitarian action. When such overlapping disasters occur, goods must be relocated to existing depots in a way which enables rapid supply to regions with new and urgent demand. At the same time, ongoing operations have to continue, i. e., the other regions should not suffer from shortages, and possible future emergencies must be taken into account. This is a planning situation under uncertainty as it is not known in advance if and where a disruption-and hence additional demand-will occur. In this paper, an optimization model for such situations is developed based on penalty costs for non-satisfied demand. A rolling horizon approach for solving the model is presented, and it is shown that taking into account the possibility of future disruptions can help to balance inventories and to reduce total non-served demand.Publicationtype: Journal Article103 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Typology of operations research methods in humanitarian logisticsPublicationtype: Conference Paper63