Increasing Stability of Crew Schedules in Airlines

In airline traffic disruptions occur frequently and cannot be totally avoided. They may lead to infeasible aircraft and crew schedules during the day of operations, due to absence of resources or violation of crew rules. The process of finding new schedules in such cases is called recovery or disruption management. The short-term recovery actions usually imply additional costs meaning that the total operational costs of a crew schedule can be significantly higher than the original planned costs. It is generally desirable to construct the schedule already in the planning phase in such a way that not just the planned costs, but the total operational costs are minimized. The goal is thus to construct schedules which remain feasible or can be recovered without high costs in cases of disturbances. This approach is generally called robust scheduling

Integrated Driver Rostering Problem in Public Bus Transit

AbstractThe driver rostering problem (DRP), arising in public bus transport companies, generates for each group of drivers a cyclic roster while management considerations, labor laws, and the preferences of drivers have to be satisfied. Optimal rosters are characterized by maximal satisfaction of drivers, minimal difference of overtime among all drivers, and minimal number of unassigned duties. The DRP is mostly solved sequentially due to its high complexity, namely firstly the rota scheduling problem, and secondly the duty sequencing problem. However, this method may generate sub-optimal rosters. In order to avoid a sub-optimal solution, the paper discusses an integrated DRP, which is solved for real-world instances and compared with the results of the sequential approach

Decision Rules for Robotic Mobile Fulfillment Systems

The Robotic Mobile Fulfillment Systems (RMFS) is a new type of robotized, parts-to-picker material handling system, designed especially for e-commerce warehouses. Robots bring movable shelves, called pods, to workstations where inventory is put on or removed from the pods. This paper simulates both the pick and replenishment process and studies the order assignment, pod selection and pod storage assignment problems by evaluating multiple decision rules per problem. The discrete event simulation uses realistic robot movements and keeps track of every unit of inventory on every pod. We analyze seven performance measures, e.g. throughput capacity and order due time, and find that the unit throughput is strongly correlated with the other performance measures. We vary the number of robots, the number of pick stations, the number of SKUs (stock keeping units), the order size and whether returns need processing or not. The decision rules for pick order assignment have a strong impact on the unit throughput rate. This is not the case for replenishment order assignment, pod selection and pod storage. Furthermore, for warehouses with a large number of SKUs, more robots are needed for a high unit throughput rate, even if the number of pods and the dimensions of the storage area remain the same. Lastly, processing return orders only affects the unit throughput rate for warehouse with a large number of SKUs and large pick orders

Decision rules for robotic mobile fulfillment systems

The Robotic Mobile Fulfillment Systems (RMFS) is a new type of robotized, parts-to-picker material handling system, designed especially for e-commerce warehouses. Robots bring movable shelves, called pods, to workstations where inventory is put on or removed from the pods. This paper simulates both the pick and replenishment process and studies the order assignment, pod selection and pod storage assignment problems by evaluating multiple decision rules per problem. The discrete event simulation uses realistic robot movements and keeps track of every unit of inventory on every pod. We analyze seven performance measures, e.g. throughput capacity and order due time, and find that the unit throughput is strongly correlated with the other performance measures. We vary the number of robots, the number of pick stations, the number of SKUs (stock keeping units), the order size and whether returns need processing or not. The decision rules for pick order assignment have a strong impact on the unit throughput rate. This is not the case for replenishment order assignment, pod selection and pod storage. Furthermore, for warehouses with a large number of SKUs, more robots are needed for a high unit throughput rate, even if the number of pods and the dimensions of the storage area remain the same. Lastly, processing return orders only affects the unit throughput rate for warehouse with a large number of SKUs and large pick orders

Theories in Business and Information Systems Engineering

Even though the idea of science enjoys an impressive reputation, there seems to be no precise conception of science. On the one hand, there is no unified definition of the extension of activities subsumed under the notion of science. According to the narrow conception that is common in Anglo-Saxon countries, science is restricted to those disciplines that investigate nature and aim at explanation and prediction of natural phenomena. A wider conception that can be found in various European countries includes social sciences, the humanities and engineering. On the other hand and related to the first aspect, there is still no general consensus on the specific characteristics of scientific discoveries and scientific knowledge

Webbasiertes Lehrveranstaltungsmanagement. Effizienzsteigerung durch horizontale Integration von Lehr-/Lerntechnologien

Die Zeit- und Kostenersparnis, die durch den Einsatz von Informations- und Kommunikationstechnologien zur Unterstützung der Lehre erzielt wird, ist oftmals geringer als der erforderliche Aufwand für die Entwicklung und Betreuung des Angebots. Effizienz – und somit schließlich die Akzeptanz der Benutzer – kann erst gesichert werden, wenn dieser Umstand aufgehoben wird. Der folgende Beitrag erläutert anhand eines Praxisbeispiels, wie durch eine horizontale Integration verschiedene Lehr- und Lernangebote organisationsübergreifend genutzt und dabei der Zeit- und Kostenaufwand minimiert werden kann. (DIPF/Orig.

A Multicriteria Multilevel Group Decision Method for Supplier Selection and Order Allocation

Supplier selection is an integral part of supply chain management (SCM). It plays a prominent role in the purchasing activity of manufacturing and trading companies. Evaluation of vendors and procurement planning requires simultaneous consideration of tangible and intangible decision factors, some of which may conflict. A large body of analytical and intuitive methods has been proposed to trade off conflicting aspects of realism and optimize the selection process. In the large companies the fields of decision makers’ (DMs) expertise are highly distributed and DMs’ authorities are unequal. On the other hand, the decision components and their interactions are very complex. These facts restrict the effectiveness of using the existing methods in practice. The authors present a multicriteria decision analysis (MCDA) method which facilitates making supplier selection decisions by the distributed groups of experts and improves quality of the order allocation decisions. A numerical example is presented and applicability of the proposed algorithm is demonstrated in the Raiffeisen Westfalen Mitte, eG in Germany

Herausforderung Bologna: Reorganisation und IT-Unterstützung als Erfolgsfaktoren einer praktischen Umsetzung

Neben der Digitalisierung der Wissenschaft wird durch die Umstellung der Studiengänge auf Bachelor- und Masterabschlüsse ein hoher Modernisierungsdruck auf Universitäten ausgeübt. Dieser Beitrag beschreibt die Faktoren einer erfolgreichen Einführung gestufter Studiengänge an einer großen Fakultät für Wirtschaftswissenschaften. Dabei wurden die Interessen aller Beteiligten gebündelt und Mehrbelastungen durch eine gezielte Prozess-Reorganisation und IT-Unterstützung entgegengewirkt. (DIPF/Orig.