International Journal of Physical Distribution & Logistics Management

Hans‐Christian Pfohl; Karin Gareis

2005 International Journal of Physical Distribution & Logistics Management

doi: 10.1108/09600030510607319

Purpose – In the German automotive industry the supplier park concept is one of the new concepts in procurement logistics, evolved in the last years. To understand the spreading of supplier parks, it is necessary to look at actual requirements in procurement logistics in the German automotive industry and find out how supplier parks can be an answer to those requirements. For this purpose it is necessary to identify indicators describing this logistics platform. The objective of this paper is the demarcation of the supplier park concept against the concept of a freight traffic center and the concept of a distribution center. Thus, suggestions for improvements of supplier parks and first impacts for new concepts in procurement logistics can be dedicated. Design/methodology/approach – The approach of this paper is to develop a descriptive model of supplier parks. The description of concepts with specific indicators has to be always the first step in dealing scientifically with new concepts emerging in practice. The paper outlines the supplier park concept in the German automotive industry with these indicators. First recommendations for the practical application of this concept are made by designing the indicators. The findings of this paper are based on an empirical investigation of the years 2000‐2002. Findings – The findings are indicators which are useful for a description and demarcation of the supplier park concept. With these indicators the supplier park concept can be characterized and demarcated against the concept of a freight traffic center and distribution center. The description model of a supplier park delivers the theoretical framework for the development of explanation and decision models. Originality/value – The indicators “objectives, participant, location, formation and operation” allow one to describe the features of supplier parks. Thus, the decision field for introducing and improving the supplier park concept is found.

Karl Inderfurth

2005 International Journal of Physical Distribution & Logistics Management

doi: 10.1108/09600030510607328

Purpose – Remanufacturing of used products is an emerging business area, which is attractive from both an economic and an environmental point of view. Aims to investigate to what extent profit orientation in product recovery management will stimulate an environmentally conscious behavior in the sense that it promotes high recovery levels. This study also seeks to focus on a product recovery system where, in the context of extended product responsibility, a manufacturer of original products is also engaged in remanufacturing used products taken back from its customers. Design/methodology/approach – For this type of a closed‐loop supply chain the optimal recovery and production policy is evaluated. By a numerical analysis, it is shown how cost‐efficient decision making affects the product recovery behavior. In a sensitivity analysis it is evaluated how various problem determinants influence the preference for product recovery. Specifically, the impact of different sources of uncertainty is investigated. Findings – Taking advantage of the respective insights, it is discussed which measures can be taken to harmonize economical and environmental‐driven behavior in product recovery management. It is shown that uncertainty in returns and demands can be a considerable obstacle to follow a consequently environmental‐benign recovery strategy within a reverse logistics system. Research limitations/implications – The analysis in this paper is restricted to stationary demand and return patterns. In a non‐stationary situation the impact of uncertainties could be even stronger, since excessive returns might happen more often. Originality/value – Focuses on important issues in product recovery management.

Grit Walther; Thomas Spengler

2005 International Journal of Physical Distribution & Logistics Management

doi: 10.1108/09600030510607337

Purpose – Owing to new legal requirements, essential changes in the field of treatment of electronic products in Germany are expected. However, consequences in terms of changes of organisation and material flows of the German treatment system are currently unknown. Thus, the objective of this contribution is to predict relevant changes occurring in this context. This lays the framework for a deduction of recommendations for political decision makers and actors of the treatment system. Design/methodology/approach – Within this contribution, a linear, activity‐based model is presented, optimising the allocation of discarded products, disassembly activities and disassembly fractions to actors of the treatment system. Parameter and model modifications allow forecasting of future developments. In a case study, the model is then applied to Lower Saxony, a federal state of Germany. This allows a validation of the model as well as an evaluation of future scenarios. Findings – Based on this analysis, impacts of new legal and economic developments on the treatment of discarded electronic products are predicted. Conclusions and recommendations for political decision makers as well as for existing disassembly companies are drawn. Originality/value – The findings of this paper allow an estimation of the impacts of new legal regulations on the existing infrastructure for treatment of electrical devices in Germany. The applied methodology can be assigned to additional product categories and can be enhanced regarding the system boundary.

Giselher Pankratz

2005 International Journal of Physical Distribution & Logistics Management

doi: 10.1108/09600030510607346

Purpose – To propose and to evaluate a new genetic algorithm (GA) for solving the dynamic pickup and delivery problem with time windows (DPDPTW). Design/methodology/approach – First, a grouping genetic algorithm (GGA) for the (static) PDPTW is described. In order to solve the dynamic problem, the GGA then is embedded in a rolling horizon framework. Special updating mechanisms are provided which assure that reusable solution knowledge is preserved over the plan revisions. The approach is evaluated using a large number of test instances with varying degrees of dynamism. Findings – The experimental results have demonstrated that the proposed approach is able to find high‐quality solutions when compared with two comparative heuristics. Research limitations/implications – Future research will be dedicated to the following issues: testing the proposed method using larger problem instances, using more sophisticated objective functions in order to further improve and evaluate the approach, integrating fast local search techniques into the genetic search, speeding up the algorithm by optimizing its implementation. Practical implications – In order to meet the increasing demands on the flexibility and the promptness of transportation services, algorithms are needed for dispatching transportation requests that arrive dynamically during the planning period. The findings of this contribution justify the employment of GAs in such dynamic transportation planning environments. Originality/value – Although the application of GAs in dynamic environments attracts growing attention, up to now no such algorithm has been published for the DPDPTW. To the best of the author's knowledge, this is the first time a GA has been applied to the DPDPTW.