Bernhard Fleischmann

The general lotsizing and scheduling problem

The GLSP (GeneralLotsizing andSchedulingProblem) addresses the problem of integrating lotsizing and scheduling of several products on a single, capacitated machine. Continuous lotsizes, meeting deterministic, dynamic demands, are determined and scheduled with the objective of minimizing inventory holding costs and sequence-dependent setup costs. As the schedule is independent of predefined time periods, the GLSP generalizes known models using restricted time structures. Three variants of a local search algorithm, based onthreshold accepting, are presented. Computational tests show the effectiveness of these heuristic approaches and are encouraging for further extensions of the basic model.ZusammenfassungDas GLSP (GeneralLotsizing andSchedulingProblem) stellt ein neues Modell zur integrierten Losgrößen- und Reihenfolgeplanung dar. Betrachtet wird eine Maschine mit begrenzter Kapazität, für die Lose in kontinuierlicher Größe und die zugehörige Auflagereihenfolge bestimmt werden sollen. Zielkriterium sind minimale Lagerund (reihenfolgeabhängige) Rüstkosten für gegebene dynamische Bedarfe mehrerer Produkte. Die Lösungen sind unabhängig von einer vorab festgelegten Periodeneinteilung des Planungszeitraums. Das GLSP verallgemeinert daher bekannte Modelle, die eine bestimmte Zeitstruktur voraussetzen. Es werden drei unterschiedliche Local-Search-Heuristiken zur Lösung des Problems präsentiert, die auf Basis des „Threshold Accepting”-Prinzips arbeiten. Der Vergleich mit heuristischen und optimalen Lösungen für ein verwandtes Problem zeigt, daß die Ergebnisse durchaus ermutigend für Erweiterungen des Modells sind.

Dynamic Vehicle Routing Based on Online Traffic Information

With the increasing availability of real-time information and communication systems in logistics, the need for appropriate planning algorithms, which make use of this technology, arises. Customers in transport markets increasingly expect quicker and more flexible fulfillment of their orders, especially in the electronic marketplace. This paper considers a dynamic routing system that dispatches a fleet of vehicles according to customer orders arriving at random during the planning period. Each customer order requires a transport from a pickup location to a delivery location in a given time window. The system disposes of online communication with all drivers and customers and, in addition, disposes of online information on travel times from a traffic management center. This paper presents a planning framework for this situation which, to our knowledge, has not yet been addressed in the literature. It then describes three routing procedures for event-based dispatching, which differ in the length of the planning horizon per event. We focus on the use of dynamic travel time information, which requires dynamic shortest path calculations. The procedures are tested and compared using real-life data of an urban traffic management center and a logistics service provider.

Time-Varying Travel Times in Vehicle Routing

Models and algorithms for vehicle routing are usually based on known constant travel times between all relevant locations, an assumption that is far from reality, particularly for urban areas. But the consideration of travel times that vary with the time of day poses two serious problems: the adaptation of the algorithms and the procurement of reliable data about the behavior of the travel times in the road network. This article describes the derivation of travel time data from modern traffic information systems. It presents a general framework for the implementation of time-varying travel times in various vehicle-routing algorithms. Finally, it reports on computational tests with travel time data obtained from a traffic information system in the city of Berlin.

The discrete lot-sizing and scheduling problem with sequence-dependent setup costs

Abstract We consider the problem of scheduling several products on a single machine so as to meet the known dynamic demand and to minimize the sum of inventory costs and sequence-dependent setup costs. The planning interval is subdivided into many short periods, e.g. shifts or days, and any lot must last one or several full periods. We formulate this problem as a travelling salesman problem with time windows and present a new procedure for determining lower bounds using Lagrangean relaxation as well as a heuristic. Computational results for problems with up to 10 products and 150 periods are reported.

Planning Hierarchy, Modeling and Advanced Planning Systems

Publisher Summary It is important to identify different types of supply chains to derive fitting management strategies. Planning systems, which try to implement these strategies operatively, also have to be tailored to the particular requirements of the type of supply chain under consideration. The chapter introduces a typology of supply chains, which is illustrated by two contrasting examples: consumer goods manufacturing and computer assembly. A general framework for deriving the corresponding planning tasks of the respective supply chain type is provided. Planning concepts that fit the planning requirements can be designed by means of hierarchical planning (HP). The HP concepts, including recent developments, are reviewed in the chapter. It is shown that a common modular architecture, which is along the lines of HP, is underlying all the advanced planning systems (APS) and the functions of the typical modules are discussed.

Strategic Planning of BMW's Global Production Network

We developed a strategic-planning model to optimize BMWs allocation of various products to global production sites over a 12-year planning horizon. It includes the supply of materials as well as the distribution of finished cars to the global markets. It determines the investments needed in the three production departments, body assembly, paint shop, and final assembly, for every site and the financial impact on cash flows. The model has improved the transparency and flexibility of BMWs strategic-planning process.

Designing distribution systems with transport economies of scale

This paper is concerned with some aspects of distribution planning which are rarely addressed in the literature: different types of distribution networks with up to three transport stages and nonlinear transport costs derived from freight tariffs. The importance of these aspects in practice is underlined and a general multi-product distribution planning model is presented. Applications to designing distribution systems in West Germany, Western Europe and recently in the unified Germany in various consumer goods industries are reported and one case is described in detail.

Strategic Network Planning

In this chapter we will focus on the long-term, strategic planning and design of the supply chain. During the strategic planning, an organization attempts to design a supply chain which will enable this organization to maximize its economic performance over an extended period of time. Together with product research and development and marketing, the supply chain is one of the essential tools for a company to achieve their strategic business goals and practices. During the strategic planning process, companies identify their key products, customer markets for these products, core manufacturing processes and suppliers of raw and intermediate materials. Virtually all organizations must redesign their supply chain from time to time to respond to changing market conditions, but the recent wave of mergers and acquisitions and the globalization of the economy have made this process even more frequent and important. For example, a company may wish to expand into a new geographical area where no infrastructure is currently in place, such as the expansion by electronics manufacturing companies into Eastern Europe after those countries adopted a market economy. Another company may wish to consolidate the duplicate distribution systems created by a merger or acquisition. Finally, strategic planning is not only used for expansion, but also for retraction, such as when the United States Armed Forces developed a strategic plan for the base closings associated with the withdrawal from Western Europe.

Customer Orientation in Advanced Planning Systems

Customer satisfaction is a major objective of Supply Chain Management. This also applies to “Advanced Planning Systems” (APS), computerized planning systems which try to support the various planning processes to be tackled in supply chains. “Order Promising” and “Demand Fulfillment” software modules of these systems are helpful in promising short and reliable customer order delivery dates and in tracking customer orders along the whole process between order entry and order delivery.

Strategic Network Design

This chapter deals with the long-term strategic planning and design of the supply chain. Section 6.1 explains the planning situation and the problem setting. Section 6.2 outlines the formulation of the problem as an optimization model and Sect. 6.3 the use of such models within the strategic planning process. Section 6.4 reviews case reports in the literature and Sect. 6.5 the software modules available in APS.