Pricing decisions in a two‑period closed‑loop supply chain game under asymmetric information and uncertainty

Strategies to increase sustainability are of growing relevance for supply chains and especially for the management of production processes. In this paper, we build on existing literature in closed-loop supply chain management and consider a two-period game-theoretic model in which product returns are reused in the manufacturing process. In all scenarios, we assume that the return rate of used products is random and not known to the players at the beginning of the planning horizon, thus, they have to deal with uncertainty in period 1. In contrast to existing literature, we will also address the circumstance that the players’ level of information in period 2, after the returns have been realized, can be linked to the collection mode in the supply chain. In Scenario A, the retailer is involved in the collection of the used products and transfers them to the manufacturer, so that symmetric information is available. In Scenario B, on the other hand, the used products reach the manufacturer directly from the customer, so that the manufacturer has an information advantage over the retailer. By comparing these scenarios and a vertically integrated supply chain benchmark case, it becomes clear that, depending on the actual return rate, the presence of private information can be either beneficial or detrimental to the manufacturer. The retailer, on the other hand, can compensate for information disadvantages in most cases over the multi-period planning period due to its position as a Stackelberg leader. Regardless of the amount of a transfer payment offered to it by the manufacturer, it prefers the collection of the goods by the manufacturer itself. These findings contribute to literature on symmetric information, where, for example, a retailer-led collection is preferred (Savaskan et al. Manage Sci 50(2):239–252, 2004) or the decision depends on the amount of the transfer payment (Modak et al. J Clean Prod 171:512–528, 2018). However, we show that cooperation between the players leads to the best results not only economically but also from an ecological point of view

On the complexity of the economic lot-sizing problem with rework of defectives

In this paper, we will show that the economic lot-sizing problem with rework of defectives is NP-hard. Therefore, we reduce it to the well-known PARTITION problem. This is in line with the findings for similar models that in-vestigate lot-sizing with remanufacturing

Wenn Zulieferer und Abnehmer eng zusammenarbeiten: Wenn Zulieferer und Abnehmer eng zusammenarbeiten: Logistische Kooperation im Rahmen des Vendor-Managed-Inventory-Konzeptes

Nachdem Unternehmen sich bisher eher mit der Reorganisation interner Prozesse beschäftigt haben, richtet sich der Blick nunmehr auf unternehmensübergreifende Geschäftsprozesse. Für das Logistikmanagement stellt insbesondere die kooperative Zusammenarbeit entlang der Wertschöpfungskette (vertikale Kooperationen) ein immer wichtiger werdendes Aufgabenfeld dar. Hierbei geht es darum, die logistischen Prozesse, die entlang der Versorgungskette (Supply Chain) auftreten, zur Kundenzufriedenheit zu gestalten. Eine Alternative, um die Produktionsund Logistikprozesse bei Beteiligung mehrerer rechtlich selbstständiger Unternehmen zu koordinieren, ist das Konzept des Vendor Managed Inventory (VMI), bei dem der Zulieferer die Disposition der Lagerbestände beim Abnehmer durchführt. Dieser Beitrag stellt das Konzept sowie verschiedene Ausgestaltungsvarianten vor.Following reorganisation of their internal business processes, many firms are now concentrating on inter-company processes. Cooperation along the value chain (vertical cooperation) is becoming an ever more important task in logistics management. The objective is to manage logistics processes along the supply chain in a manner which promotes customer satisfaction. Vendor-managed inventory (VMI) is one concept able to coordinate the production and logistics processes between several legally independent companies, placing responsibility for management of the customer’s inventory in the hands of the supplier. In this paper, the VMI concept is presented and different arrangements are discussed

Ostdeutschlands Transformation seit 1990 im Spiegel wirtschaftlicher und sozialer Indikatoren. 2. aktualisierte und verbesserte Auflage

20 Jahre nach der "friedlichen Revolution" und dem darauffolgenden Herstellen der staatlichen Einheit Deutschlands legt das IWH erneut eine Dokumentation der gesellschaftlichen, vor allen Dingen der wirtschaftlichen Entwicklung vor. Ziel ist es, anhand von Zahlen, Schaubildern und Tabellen mit entsprechenden Erklärungen die Vielschichtigkeit des Wandels der Neuen Länder aufzuzeigen. Damit fällt auch die Bewertung differenziert aus: Es gibt eine weitgehend modernisierte Infrastruktur, das erste, was an "blühende Landschaften" erinnern mag. Einige Unternehmen und Standorte konnten sich mit großem wirtschaftlichen Erfolg die Weltmarktführerschaft in wesentlichen Technologien sichern. Aber es gibt auch einen massiven Bevölkerungsverlust, sich entleerende Gebiete. Manche Städte und erhebliche Teile des ländlichen Raums suchen eine neue Aufgabe in der nationalen und internationalen Arbeitsteilung. "Damit zusammenwächst, was zusammengehört" - dieses Bild ist damit kontrovers zu beleuchten. Wenige haben gedacht, dass 40 Jahre Teilung und Zwangswirtschaft so lange in ihren Folgen vorhalten würden. Post-Transformationsgesellschaften, zu denen auch die der Neuen Bundesländer zählen, schütteln ihre Vergangenheit nur langsam ab: Der bürgerliche, insbesondere auch wirtschaftlich tätige Mittelstand entwickelt sich erst; noch viele Jahre des erfolgreichen Wirtschaftens liegen vor ihm, bis er in der Breite die hohe Internationalität Westdeutschlands erreicht hat. Denn dort sind Globale Mittelständische Unternehmen, so genannte "GMUs", als spezialisierte Nischenanbieter weltbekannt. Internationale Unternehmenszentralen fehlen in den Neuen Bundesländern vollkommen, was in erheblichem Maße auch die weiterhin persistente Einkommenslücke gegenüber Westdeutschland erklärt und zugleich auf einige Folgeerscheinungen verweist, beispielsweise verringerte Erwerbstätigkeitschancen, eine gegenüber den Alten Ländern geringere Kaufkraft. Folgen für die Urbanität der Städte sind unausweichlich ..

Minimizing the earliness–tardiness for the customer order scheduling problem in a dedicated machine environment

The customer order scheduling problem has garnered considerable attention in the recent scheduling literature. It is assumed that each of several customer orders consists of several jobs, and each customer order is completed only if each job of the order is completed. In this paper, we consider the customer order scheduling problem in a machine environment where each customer places exactly one job on each machine. The objective is to minimize the earliness–tardiness, where tardiness is defined as the time an order is finished past its due date, and earliness is the time a job is finished before its due date or the completion time of the corresponding order, whichever is later. Even though the earliness–tardiness criterion is an important objective for just-in-time production, this problem has not been studied in the context of the customer order scheduling problem. We provide a mixed-integer linear programming (MILP) formulation for this problem and derive multiple problem properties. Furthermore, we develop six different heuristics for this problem configuration. They follow the structure of the iterated greedy algorithm and additionally use a refinement function in which they differ. In a computational experiment, the algorithms were compared with each other and outperformed a solver solution of the MILP, which proves their ability to efficiently solve the problem configuration

A branch-and-cut algorithm for vehicle routing problems with three-dimensional loading constraints

This paper presents a new branch-and-cut algorithm based on infeasible path elimination for the three-dimensional loading capacitated vehicle routing problem (3L-CVRP) with different loading problem variants. We show that a previously infeasible route can become feasible by adding a new customer if support constraints are enabled in the loading subproblem and call this the incremental feasibility property. Consequently, different infeasible path definitions apply to different 3L-CVRP variants and we introduce several variant-depending lifting steps to strengthen infeasible path inequalities. The loading subproblem is solved exactly using a flexible constraint programming model to determine the feasibility or infeasibility of a route. An extreme point-based packing heuristic is implemented to reduce time-consuming calls to the exact loading algorithm. Furthermore, we integrate a start solution procedure and periodically combine memoized feasible routes in a set-partitioning-based heuristic to generate new upper bounds. A comprehensive computational study, employing well-known benchmark instances, showcases the significant performance improvements achieved through the algorithmic enhancements. Consequently, we not only prove the optimality of many best-known heuristic solutions for the first time but also introduce new optimal and best solutions for a large number of instances.Comment: 33 pages, 13 figures, 7 tables, Submitted to Transportation Scienc

Solving Practical Railway Crew Scheduling Problems with Attendance Rates

Arising from a practical problem in German rail passenger transport, a prototype for a multi-period railway crew scheduling problem with attendance rates for conductors is developed and evaluated in this paper. The consideration of attendance rates is of increasing importance in regional transport networks and requires decision support. For this purpose business analytics is applied in order to offer an approach to transform real-world data to concrete operational decision support (action). The focus here is on the analysis step using a new set covering model with several essential restrictions integrated for the first time. A hybrid column generation approach is applied, which solves the pricing problem by means of a genetic algorithm. The artifact is evaluated with the help of a case study of three real-world transport networks. It is shown that the hybrid solution approach is able to solve the problem more effectively and efficiently compared to conventional approaches used in practice

Gymnasiale Oberstufe flexibilisieren durch Stundenplanung

Eine flexible Oberstufe als pädagogische Innovation verfolgt das Ziel, individuelle Bildungswege und mehr Bildungsgerechtigkeit zu ermöglichen. Besonders Modelle, die auf Wahlfreiheit und individuelle Förderung abzielen, stellen Schulen dabei vor neue organisatorische Anforderungen. So erweist sich die aus einer Flexibilisierung resultierende komplexe Stundenplanung oft als Hürde für eine adäquate Umsetzung und übersteigt die organisatorischen Kapazitäten von Schulen. Das in diesem Beitrag vorgestellte Projekt GO-flexi adressiert diese Herausforderung. Ausgehend von der Analyse organisatorischer und pädagogischer Anforderungen in sechs Kooperationsschulen mit flexibler Oberstufe aus drei Bundesländern werden die spezifischen Herausforderungen der Stundenplanung rekonstruiert. Aus den gewonnenen Erkenntnissen und auf Basis der veränderten Anforderungen sollen innovative Ansätze zur digital gestützten Stundenplanung für flexible Oberstufen entwickelt und erprobt werden. A flexible upper secondary school as a pedagogical innovation aims at enabling individual educational pathways and more equal opportunities. However, models based on freedom of choice and individual support present schools with new organizational challenges. For example, the complex timetabling resulting from flexibilization often proves to be an obstacle to adequate implementation and exceeds the organizational capacities of schools. The GO-flexi project presented in this article addresses this challenge. Based on the analysis of organizational and pedagogical requirements in six German schools with a flexible upper secondary, the specific challenges of timetabling are reconstructed. Based on the insights gained, innovative approaches to digitally supported timetabling for flexible upper secondary schools will be developed and tested

Challenges and the Need to Integrate Rolling Stock and Crew Scheduling for Efficient Railway Operations

The planning of traction units and drivers is a crucial strategic and tactical planning problem for railway companies. Due to the complexity of the individual problems, large railway undertakings typically solve these problems in a sequential manner, i.e., they first generate circulation plans and then use them to generate shift plans. As a consequence, the achievable quality of the shift plans depends on the operational efficiency of the circulation plan, and information dependencies between the two planning steps cannot be exploited. This paper presents different types of integrated circulation and shift planning. An investigation of the inherent challenges and benefits of an integrated planning approach is presented, initial approaches for data structures and algorithms are introduced, and first results are shown