Disposition Choices Based on Energy Footprints instead of Recovery Quota

This paper addresses the impact of disposition choices on the energy use of closed-loop supply chains. In a life cycle perspective, energy used in the forward chain which is locked up in the product is recaptured in recovery. High quality recovery replaces virgin production and thereby saves energy. This so called substitution effect is often ignored. Governments worldwide implement Extended Producer Responsibility (EPR). Policies are based on recovery quota and not effective from an energy point of view. This in turn leads to unnecessary emissions of amongst others CO2. This research evaluates current EPR policies and presents six policy alternatives from an energy standpoint. The Pareto-frontier model used is generic and can be applied to other closed loops supply chains under EPR, exploiting the substitution effect. The measures modeled are applied to five WEEE cases. We discuss results, pros an cons of various alternatives and complementary measures that might be taken.extended producer responsibility;disposition;energy perspective;substitution effect;government policies;Pareto efficiency

Last Time Buy and Control Policies With Phase-Out Returns: A Case Study in Plant Control Systems

This research involves the combination of spare parts management and reverse logistics. At the end of the product life cycle, products in the field (so called installed base) can usually be serviced by either new parts, obtained from a Last Time Buy, or by repaired failed parts. This paper, however, introduces a third source: the phase-out returns obtained from customers that replace systems. These returned parts may serve other customers that do not replace the systems yet. Phase-out return flows represent higher volumes and higher repair yields than failed parts and are cheaper to get than new ones. This new phenomenon has been ignored in the literature thus far, but due to increased product replacements rates its relevance will grow. We present a generic model, applied in a case study with real-life data from ConRepair, a third-party service provider in plant control systems (mainframes). Volumes of demand for spares, defects returns and phase-out returns are interrelated, because the same installed base is involved. In contrast with the existing literature, this paper explicitly models the operational control of both failed- and phase-out returns, which proves far from trivial given the nonstationary nature of the problem. We have to consider subintervals within the total planning interval to optimize both Last Time Buy and control policies well. Given the novelty of the problem, we limit ourselves to a single customer, single-item approach. Our heuristic solution methods prove efficient and close to optimal when validated. The resulting control policies in the case-study are also counter-intuitive. Contrary to (management) expectations, exogenous variables prove to be more important to the repair firm (which we show by sensitivity analysis) and optimizing the endogenous control policy benefits the customers. Last Time Buy volume does not make the decisive difference; far more important is the disposal versus repair policy. PUSH control policy is outperformed by PULL, which exploits demand information and waits longer to decide between repair and disposal. The paper concludes by mapping a number of extensions for future research, as it represents a larger class of problems.spare parts;reverse logistics;phase-out;PUSH-PULL repair;non stationary;Last Time Buy;business case

Design Principles for Closed Loop Supply Chains

In this paper we study design principles for closed loop supply chains. Closed loop supply chains aim at closing material flows thereby limiting emission and residual waste, but also providing customer service at low cost. We study 'traditional' and 'new' design principles known in the literature. It appears that setting up closed loop supply chains requires some additional design principles because of sustainability requirements. At the same time however, we see that traditional principles also apply. Subsequently we look at a business situation at Honeywell. Here, only a subset of the relevant design principles is applied. The apparent low status of reverse logistics may provide an explanation for this. To some extent, the same mistakes are made again as were 20 years ago in, for instance, inbound logistics. Thus, obvious improvements can be made by applying traditional principles. Also new principles, which require a life cycle driven approach, need to be applied. This can be supported by advanced management tools such as LCA and LCC.reverse logistics;case-study;closed loop supply chains

Experimental implementation of a real-time token-based network protocol on a microcontroller

The real-time token-based RTnet network protocol has been implemented on a standard Ethernet network to investigate the possibility to use cheap components with strict resource limitations while preserving Quality of Service guarantees. It will be shown that the proposed implementation is feasible on a small network. For larger networks a different approach is necessary, using delegation by means of proxies. A delegation proposal will be discussed. For small networks it is possible to use a PIC microcontroller in combination with a standard Ethernet controller to run the RTnet network protocol. As more systems are added to the network the performance of this combination becomes insufficient. When this happens it is necessary for the microcontroller to delegate some tasks to a more powerful master and to organize a low-level communication protocol between master and slave

Dataset of the Refrigerator Case: design of closed loop supply chains

This paper contains the dataset for the refrigerator case concerning the design of a production and return network for refrigerators. Section 1 emphasises the major changes to the problem structure and assumptions used by Umeda et al. (1999). Section 2 contains the parameter settings. Section 3 contains the distance matrix for all locations.supply chain management;reverse logistics;facility location;network design;product design