Yulia Lapko
email: yulia.lapko@polimi.it

Paolo Trucco
email: paolo.trucco@polimi.it

Andrea Trianni
email: andrea.trianni@polimi.it

Cali Nuur
email: cali.nuur@indek.kth.se

Implications for Collaborative Development of Reverse Distribution Network: A System Perspective

Keywords: resource scarcity, collaboration, reverse distribution network

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Available research indicates increasing constrains on availability and production of resources [START_REF]IEA: Energy technology perspectives 2008: scenarios & strategies to 2050[END_REF][START_REF] Prior | Resource depletion, peak minerals and the implications for sustainable resource management[END_REF] as well as that resource scarcity is turning to be the major problem for many industries [START_REF]PwC: Minerals and metals scarcity in manufacturing: the ticking time bomb[END_REF]. Economic growth and rapid increase of population impose great pressure on the supply of resources while at the same time, environmental and social cost of mining is increasing [START_REF] Prior | Resource depletion, peak minerals and the implications for sustainable resource management[END_REF]. Several studies have discussed the problem of resource scarcity and have criticality assessed the role of raw materials on economic performance, supply risk, vulnerability to supply disruptions and ecological risks [START_REF] Achzet | How to evaluate raw material supply risks-an overview[END_REF][START_REF] Erdmann | Criticality of non-fuel minerals: a review of major approaches and analyses[END_REF]. They have highlighted how the scarcity of Critical Raw Materials (CRM) can become a bottleneck for deployment of emerging technologies (e.g., electronics and green energy) due to high geographical concentration of supply, low recycling rates and low (or even impossible) substitutability [START_REF]Critical Mineral Strategy[END_REF][START_REF]European Commission: Critical raw materials for the EU[END_REF][START_REF]Hoc Working Group on Defining Critical Raw Materials[END_REF][START_REF] Moss | Critical Metals in Strategic Energy Technologies[END_REF]. Although technology plays important role for mitigation risks related to resource scarcity, there is a need for the supply chains that could ensure both resource efficiency and secure sources of their supply [START_REF] Krautkraemer | Economics of Natural Resource Scarcity : The State of the Debate[END_REF].

Reverse Distribution Network (RDN) has been proposed as a possible solution to offset the challenges related to resource scarcity [START_REF] Krautkraemer | Economics of Natural Resource Scarcity : The State of the Debate[END_REF]. RDN can be defined as the logistics structure for managing the backward flow of materials (from customers back to suppliers). RDN is also important since companies are required to engage into material recovery operations by governmental policies [11], downstream partners and other stakeholders [START_REF] Bai | Flexibility in reverse logistics: a framework and evaluation approach[END_REF]. Nevertheless, RDNs are the subject of a wide range of uncertainties, which create many obstacles for network development and maintenance. As a result, companies keep struggling to set up an efficient system [START_REF] Bai | Flexibility in reverse logistics: a framework and evaluation approach[END_REF][START_REF] Govindan | Analysis of third party reverse logistics provider using interpretive structural modeling[END_REF].

In order to gain understanding of such a complex phenomenon as RDN, it is important to take into consideration all elements within their interconnections. System perspective allows to meet this requirement. Adopting this perspective highlights two implications for RDN development (based on the systems theory [START_REF] Skyttner | General systems theory: origin and hallmarks[END_REF][START_REF] Ackoff | Creating the corporate future: Plan or be planned for[END_REF][START_REF] Yourdon | Modern Structured Analysis[END_REF]): consistency and complexity. Firstly, it is necessity to ensure consistency of the system through the pursuit of involved parties to the common (system) goal -maximization of the value creation (where value defined as the amount of recovered (recycled) materials). Secondly, complexity of RDN leads to decrease of the network agility. As RDN is a backbone solution for the problem of resource scarcity, it is necessary to ensure its adaptability to the changing environment.

Against this background, this paper aims at identifying the new prospects (new business opportunities, new forms of organization) for RDN development. It examines the existing knowledge base using the lens of the system perspective (enabling consistency and dealing with complexity).

Apart from this introduction, the paper is structured as follows. The subsequent section presents the methodology of the paper. In section 3, the results of the review are presented. The paper ends with conclusions and suggestions for further studies.

Methodology

To address the research aim, a literature review was performed. A sample of articles was selected from Scopus database using the following steps. An initial search using the four key words: 'green supply chain', 'closed loop supply chain', 'reverse logistics', 'product recovery network' was conducted on eight subject areas: engineering, business, management and accounting, decision science, environmental science, energy, economics econometrics and finance, material science, chemical engineering. The results were limited to academic articles from peer-reviewed journals. Only articles published after 1999 were considered, as at that time the EU started to shape new regulatory framework for companies' operations through new environmental-related directives, e.g., [11]. Moreover, according to the Scopus, the majority of research was developed after 1999, with a high attention from academia during last ten years. The relevance of the articles was evaluated in terms of their relation to resource scarcity mitigation and operating channel development, and was conducted through review of title and abstract in the first place. Afterwards, the selection was refined by reviewing the full texts of the articles. At the end, an examination of references cited in each relevant literature was performed in order to find additional sources of information.

Results

Our results show that the literature, devoted to reverse distribution networks, can be divided in two streams: network design modelling and practical issues related to operating channel implementation. The former issues were discussed by [START_REF] Akçalı | Network Design for Reverse and Closed-Loop Supply Chains : An Annotated Bibliography of Models and Solution Approaches[END_REF], who summarized the addressed questions through number, location, type and capacity of recovery activities. Researches [START_REF] Fleischmann | A characterisation of logistics networks for product recovery[END_REF] Another stream of research has more business orientation and deals with implementation of the reverse distribution networks. That stream is mainly rep-resented by the following topics: collection of cores, remanufacturing activities and selection of suppliers and third party service providers. Researchers [START_REF] Savaskan | Closed-Loop Supply Chain Models with Product Remanufacturing[END_REF][START_REF] Senthil | A Decision Making Methodology for the Selection of Reverse Logistics Operating Channels[END_REF] examine operating channels for collection activities arranged through different options (e.g., though Original Equipment Manufacturer (OEM), existing retailers from forward distribution, third party service providers and a joint venture). [START_REF] Östlin | Importance of closed-loop supply chain relationships for product remanufacturing[END_REF] proposed different strategies to acquire cores from customers (e.g., buy-back and voluntary based relationships). Great body of research is also dedicated to remanufacturing issues. Although researchers identify benefits of performing remanufacturing activities by (OEM) -e.g., secured spare part supply [START_REF] Seitz | Meeting the Closed-Loop Challenge[END_REF] and balanced production lines [START_REF] Bulmuş | Capacity and production decisions under a remanufacturing strategy[END_REF] -there are still a lot of uncertainties and risks, like cannibalization of the sales for the OEM's new products, which lead to designing products to prevent remanufacturing [START_REF] Xiong | Don't forget your supplier when remanufacturing[END_REF].

Research in selection of suppliers and third party service providers is presented in different sets of criteria and algorithms that should be applied for estimation of a potential supplier/service provider [START_REF] Meade | A conceptual model for selecting and evaluating third-party reverse logistics providers[END_REF].

Thus, it is worth noting that both streams of the literature were developed with focuses on different issues. Among the exceptions, we can mention studies of [START_REF] Blackhurst | An Empirically Derived Framework of Global Supply Resiliency[END_REF], who applied systems theory to formulate supply resiliency reducers; [START_REF] Simatupang | The Collaborative Supply Chain[END_REF][START_REF] Simatupang | Applying the theory of constraints to supply chain collaboration[END_REF], who developed constructs for successful collaborations in supply chains; [START_REF] Sarkis | A: boundaries and flows perspective of green supply chain management[END_REF] who presented a boundaries and flows perspective of green supply chain management; [START_REF] Pokharel | Perspectives in reverse logistics: A review[END_REF], who reviewed reverse logistics through inputs, processes and output; [START_REF] Xiong | Don't forget your supplier when remanufacturing[END_REF], who demonstrated the necessity to involve upstream actors for reverse operating channel development. Furthermore, little attention were paid to generalization of findings and developing guidelines for industries on how responsibilities should be divided in the network and which operating channel is suitable to every process. The latter issue is very important as many companies, that successfully implement forward logistics operations, have difficulties in efficient management of reverse direction of materials flows [START_REF] Bai | Flexibility in reverse logistics: a framework and evaluation approach[END_REF][START_REF] Govindan | Analysis of third party reverse logistics provider using interpretive structural modeling[END_REF].

There are few examples of OEMs that have integrated reverse logistics operations as a result of proactive planning measures, the majority is pushed by legislation to take responsibility for end-of-life products [11] or by requirements of a downstream partner and a stakeholder [START_REF] Bai | Flexibility in reverse logistics: a framework and evaluation approach[END_REF]. It is common, that OEMs tend to displace the burdensome processes through outsourcing of reverse logistics operations rather than involve them into their business models [START_REF] Bai | Flexibility in reverse logistics: a framework and evaluation approach[END_REF], [START_REF] Krikke | Revealing an invisible giant: A comprehensive survey into return practices within original (closed-loop) supply chains[END_REF]. This strategy leads to the loss of control of the further materials streams (strategic resources). Furthermore, it causes separation of decision-making and may lead to the conflicts of interests, as the decisions might not comply with the goal of the system in the whole and subsystem in particular. Therefore, problems of managing reverse flows also might be explained by lack of system consistency.

According to the systems theory, efficient operation of RDN depends on its consistency and complexity. Through the literature review, it was identified that both of them could be ensured through collaborations. Firstly, collaborations can help enable shared vision on the RDN development (pursuit to the common system goal), and secondly, they can help reduce uncertainties related to reverse flow operations thanks to collective creation and sharing of knowledge between involved parties. For example, according to the study [START_REF] Xiong | Don't forget your supplier when remanufacturing[END_REF], independent attempts of OEM to develop additional flows of resources through product recovery options can push suppliers to adjust resource/component prices, and eventually devalue OEM's activities to ensure supply and improve performance efficiency.

Supply chain collaboration means that "two or more independent companies work jointly to plan and execute supply chain operations with greater success then when acting in isolation" [27, p. 19]. Collaborations could be vertical, horizontal and lateral [START_REF] Simatupang | The Collaborative Supply Chain[END_REF], all these types offer new prospects for development of RDN: collaborations between OEMs to perform reprocessing activities (horizontal), between OEM and suppliers to arrange a secondary resource flow (vertical), combination of previous examples would form a lateral collaboration.

Collaborative relationships as an important construct of an efficient supply chain performance has found support in several theories and perspectives [START_REF] Simatupang | The Collaborative Supply Chain[END_REF], [START_REF] Whitten | Triple-A supply chain performance[END_REF][START_REF] Frohlich | Arcs of integration: an international study of supply chain strategies[END_REF]. For example, [START_REF] Cao | Supply chain collaboration: Impact on collaborative advantage and firm performance[END_REF] considered supply chain collaborations from a transaction theory and resource based view. In addition, [START_REF] Sarkis | An organizational theoretic review of green supply chain management literature[END_REF] discussed collaborations both from resource dependence theory and information theory, while [START_REF] Bell | Natural resource scarcity and the closed-loop supply chain: a resource-advantage view[END_REF] used the lens of resource-advantage theory. Therefore, through collaboration it is possible to acquire necessary competences, to reach required level of trust and control between actors, to eliminate non-value-adding activities [START_REF] Frohlich | Arcs of integration: an international study of supply chain strategies[END_REF][START_REF] Cao | Supply chain collaboration: Impact on collaborative advantage and firm performance[END_REF], [START_REF] Flynn | The impact of supply chain integration on performance: A contingency and configuration approach[END_REF]. Moreover, [START_REF] Schultmann | Modeling reverse logistic tasks within closed-loop supply chains: An example from the automotive industry[END_REF] noted that collaborative initiatives help to share significant costs of establishment and maintenance of a recovery network as well as obtain required infrastructure and expertise. Collaborative development should help mitigate operations challenges of reverse flows, for example, by ensuring required capacity of flows from economic perspectives. Therefore, it is possible to consider collaborative development as an enabler and enhancer of building secondary streams of supply, what becomes increasingly important nowadays, when the problem of resource scarcity is raised.

Conclusion

The aim of this paper was to identify the new prospects (new business opportunities, new forms of organization) for RDN development based on examination of existing knowledge base through the lens of system perspective (enabling consistency and dealing with complexity). Three major findings were highlighted.

Firstly, there is a gap in terms of providing a system picture of forward and reverse operations. There are different streams that focus on various particular issues without taking into consideration holism of the system and its consistency. Few efforts were put into generalization of findings and prescribing guidelines for industries on how the network should be developed in a stable way (papers have rather conceptual than practical orientation). The influence of the made decisions on performance efficiency of a system in the whole and its parts in particular requires further examination.

Secondly, the system perspective for RDN development highlights two implications: it is suggested to develop RDN to enable efficiency and effectiveness of the whole system rather than with orientation to the benefit of a particular stakeholder; it is necessary to develop RDN in a way to handle its complexity without following drawbacks for network adaptability.

Finally, it was identified that collaborative relationships can address requirements from both implications of the system perspective. They offer great opportunities to develop RDN. It is necessary to gain better understanding of creating new business opportunities, forms of organization and their influence on the system performance.

  Models tend to use objective function to minimize costs of reverse distribution or maximize profit, what does not meet the necessity to pursue the system objective to maximize the value of returned items.

examined networks in relation to a degree of centralization, number of levels, links with other networks, open vs closed loop structures, degree of branch co-operation. This stream of research mainly focuses on examination of structural, configuration issues of reverse distribution networks. It should be noted that existing models suffer several limitations and simplifications (e.g., considering only single-entity flow or only single reprocessing option), what makes developed models very specific.

Acknowledgments. This paper is produced as part of the EMJD Programme European Doctorate in Industrial Management (EDIM) funded by the European Commission, Erasmus Mundus Action 1.


Yoshitaka Tanimizu
email: tanimizu@osakafu-u.ac.jp

Kenta Matsui

Yuusuke Shimizu

Koji Iwamura

Nobuhiro Sugimura

Negotiation Strategy for Economical Reuse in Closed-Loop Supply Chains

Keywords: Closed-loop supply chain, Reverse supply chain, Reuse, Negotiation, Scheduling, Genetic algorithm, Weibull distribution

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Environmental problems are recognized as one of the most serious issues in these last few decades. Many manufacturing enterprises focus on incorporating not only economical but also environmental concerns into their strategic decisions [START_REF]Supply Chain Monitor "How Mature is the Green Supply Chain?[END_REF]. Green supply chain management [START_REF] Srivastava | Green Supply-Chain Management: a State-of-the-Art Literature Review[END_REF][START_REF] Sarkis | An Organizational Theoretic Review of Green Supply Chain[END_REF] and sustainable supply chain management [START_REF] Seuring | From a Literature Review to a Conceptual Framework for Sustainable Supply Chain Management[END_REF][START_REF] Gupta | Sustainable Supply Chain Management: Review and Research Opportunities[END_REF][START_REF] Hassini | A Literature Review and a Case Study of Sustainable Supply Chains with a Focus on Metrics[END_REF][START_REF] Seuring | A Review of Modeling Approaches for Sustainable Supply Chain Management[END_REF] have gained increasing attention within both academia and industry. The concept of the green supply chain management (GrSCM) covers all the phases of a product's life cycle, from the extraction of raw materials through the design, production and distribution phases, to the use of products by consumers and their disposal at the end of the product's life cycle including reconditioning, reuse, and recycling of products. Products and materials are returned from customers to suppliers or manufacturers through reverse supply chains in order to be recycled, reused or reconditioned. Gungor and Gupta [START_REF] Gungor | Issues in Environmentally Conscious Manufacturing and Product Recovery: a Survey[END_REF] indicated that the effort must be made for environmentally conscious manufacturing and product recovery systems to be profitable so that the incentive for development and planning of these systems continues. Then, it is required to establish a method for reconditioning, reuse, and recycling of used products in consideration of the feasibility of realizing a balance between environmental and economic concerns.

Previous study have proposed a basic model of closed-loop supply chains and a negotiation protocol for reusing products in consideration of economic efficiency [START_REF] Tanimizu | Modeling and Simulation of Closed-Loop Supply Chains Considering Economic Efficiency[END_REF]. The negotiation protocol provides a method for synchronizing the demand of reusable parts and the supply of used products among the organizations in the closed-loop supply chains. However some used products may become waste products by inconsistency between the demand and the supply of the used products from the viewpoint of product value. This study improves the negotiation protocol for further increasing the reused products and reducing the waste. A customer usually discards a product by stochastic means in consideration of its life cycle. New protocol provides a customer with a method for discarding a product systematically. A remanufacturer can prospectively enter into a contract with a customer through negotiation with the customer in consideration of both the required prices from the remanufacturer and the possible time to dispose of the used product from the customer.

The reminder of this paper is organized as follows. Section 2 shows literature review. Section 3 briefly describes the previous supply chain model. Section 4 explains new negotiation protocol. Finally, Section 5 demonstrates experimental results.

Literature Review

A large number of literatures have been published on a closed-loop supply chain which involves studies on network design problems, product acquisition management, marketing-related issues, etc. [START_REF] Llgin | Environmentally Conscious Manufacturing and Product Recovery (ECMPRO): A Review of the State of the Art[END_REF]. Guide et al. [START_REF] Guide | Building Contingency Planning for Closed-Loop Supply Chains with Product Recovery[END_REF] takes a contingency approach to explore the factors that impact production planning and control for closed-loop supply chains that incorporate product recovery. Nielsen and Bruno [START_REF] Nielsen | Closed Loop Supply Chains for Sustainable Mass Customization[END_REF] analyzed the possibility to utilize closed loop supply chains in mass customization settings and required certain aspects to be considered regarding product design as well as manufacturing and supply chain design. Hassini et al. [START_REF] Hassini | A Literature Review and a Case Study of Sustainable Supply Chains with a Focus on Metrics[END_REF] indicated that quite few papers addressed the pricing issue in a sustainable supply chain context during the last decade. The market requires environmentally conscious products, such as electric vehicles and wind turbines. However, most of them include rare earths and other rare materials in main component parts, such as batteries and magnets. The U.S. Department of Energy reports that five rare earth elements, such as dysprosium, terbium, europium, neodymium and yttrium, are found to be critical in the short term (present -2015) and other elements, such as cerium, indium, lanthanum and tellurium, are found to be near-critical [START_REF]Critical Materials Strategy[END_REF]. The approach to proactively address material supply risks and prevent supply chain disruptions while building a robust clean energy economy has three pillars: achieving globally diverse supplies, identifying appropriate substitutes, and improving capacity for recycling, reuse and more efficient use of critical materials. Used products that incorporate rare resources like rare earths can be considered as a valuable resource.

A product is usually discarded in consideration of its life cycle. Takata et al. [START_REF] Takata | Collection Rate Estimation Model in Closed-Loop Manufacturing[END_REF] analyzed the actual life cycle data of copying machine. Based on the analysis of the data, they proposed several models for identifying a collection rate and a discard rate of copying machines. Umeda et al. [START_REF] Umeda | Analysis of Reusability using 'Marginal Reuse Rate[END_REF] analyzed product lifecycles of several products, such as a single use camera, a photocopier, and an automatic teller machine (ATM), from the viewpoint of the reusability. They point out that a product can be reused only when a manufacturer manufactures and sells same types of products in the market. In consideration of the reusability of product in the market, the used product should be returned from customers to suppliers or manufacturers as soon as possible, since the product life cycle appears to becoming shorter in recent years.

A lot of used products may become waste products in traditional recovery approaches, since customers discard products without consideration for reuse of the products whenever they want. A strategy for economical reuse of products is required to collect suitable products from customers and to provide manufacturers with reusable parts disassembled from the used products. Our study proposes a negotiation protocol which synchronizes the demand of reusable parts and the supply of used products among the organizations in the closed-loop supply chains. In the case where a lot of usable parts are required for generating new products, customers are stimulated to discard products for reuse. On the other hand, when few parts are required, customers are discouraged from discarding products. As if the remanufacturer deals with customers like virtual warehouses, the remanufacturer can economically collect suitable used products without various kinds of additional cost for warehouse and safety stock.

3

Previous Supply Chain Model

Modeling of Forward Supply Chains

This section briefly describes a model of forward and reverse supply chains which we have proposed in previous studies [START_REF] Gungor | Issues in Environmentally Conscious Manufacturing and Product Recovery: a Survey[END_REF][START_REF] Tanimizu | Multi-Agent Based Dynamic Supply Chain Configuration Considering Production Schedules[END_REF][START_REF] Tanimizu | Flexible Multi-Layered Dynamic Supply Chain Models with Cooperative Negotiation[END_REF], in order to help understanding our closed-loop supply chain strategy. The previous studies have represented a framework for dynamically forming and reconfiguring a supply chain as a dynamic supply chain [START_REF] Tanimizu | Multi-Agent Based Dynamic Supply Chain Configuration Considering Production Schedules[END_REF][START_REF] Tanimizu | Flexible Multi-Layered Dynamic Supply Chain Models with Cooperative Negotiation[END_REF]. Each organization in the supply chains can change business partners for every order to find suitable business partners and enter into profitable contracts. A three-layered supply chain model consisting of a client, a manufacturer, and a supplier has been proposed as a basic model of forward supply chain which involves make-to-order (MTO) companies with no inventories [START_REF] Tanimizu | Flexible Multi-Layered Dynamic Supply Chain Models with Cooperative Negotiation[END_REF]. It is assumed that only the supplier has sufficient raw materials but no inventory of final products. The model has provided with both the negotiation process to determine the suitable prices and delivery times of products among the three-layered organizations and the modification process of the production schedules in the supplier and the manufacturer. A client and a manufacturer sequentially send orders which include the requirements of delivery times and prices of the ordered products. A supplier and a manufacturer modify their existing production schedules by using a genetic algorithm (GA) and send offers for the orders, respectively. The offers include information about possible delivery times and bid prices of the ordered products. The actual delivery times and prices are determined by the negotiation processes among the organizations.

3.2

Modeling of Closed-Loop Supply Chains

The forward supply chain model extended to a closed-loop supply chain model consisting of both MTO companies in forward supply chains and remanufacturing-toorder companies in reverse supply chains [START_REF] Gungor | Issues in Environmentally Conscious Manufacturing and Product Recovery: a Survey[END_REF]. Figure 1 shows a basic model of a closed-loop supply chain. A model component in the reverse supply chain receives a used product from a client and provides assembly manufacturers with usable parts. The component is referred to as a remanufacturer in the study.

Fig. 1. Closed-loop supply chain model

A remanufacturer has neither stock of usable parts nor used products. A remanufacturer generates an order for used product and sends it to clients when the remanufacturer receives an order for a usable part from a manufacturer. After receiving an offer for a used product from a client, a remanufacturer generates an offer for a usable part and sends it to a manufacturer. A remanufacturer modifies its disassembly schedule and estimates the possible delivery time dtr F s,h,n and the bid price pcr F s,h,n of the usable part by using the following equations. A remanufacturer considers a balance between supply and demand of reusable parts in the negotiation protocol. When a lot of usable parts are required by manufacturers, a remanufacturer stimulates clients to discard products for reuse by indicating high required prices for the used products to the clients. The clients discard products even if the products don't satisfy the condition of their life cycles estimated based on the Weibull distribution which is commonly used to model life data [START_REF] Mazhar | Remaining Life Estimation of Used Components in Consumer Products: Life Cycle Data Analysis by Weibull and Artificial Neural Networks[END_REF]. On the other hand, when few usable parts are required, remanufacturers indicate low required prices to discourage clients from discarding products. Then, the remanufacturer can increase the amount of reused products whenever they want and reduce waste products.

n h s F n h s ctr dtr , , , ,  (1)
       G g r n s Rv g h s n h s n h s n h s F n h s pnr pnr rwr tcr pcr 1 ) , , ( , , , , , , , , , , (2)

Negotiation Protocol

This study improves the negotiation protocol to increase the reusability of products. There are three ways for a remanufacturer to obtain used products in the 1. Push type discarding strategy: This is a conventional approach. A client discards a product by stochastic means in consideration of its life cycle. Failure rate of product is usually used to estimate when a client discards a product. The Weibull distribution is used in the study to estimate product's life cycle. A client discards a product, when it has been used beyond its life cycle. The discarded products should be stored temporarily, since a client does not consider the condition of reuse of the product. A remanufacture can obtain only the stored product for reuse. In the case where no remanufacturers need the stored product for a certain period, it must be disposed as a waste product. 2. Pull type discarding strategy: This is proposed in the previous research. A remanufacturer stimulates the intention of a client to discard a product, when a used product is required for reuse. A remanufacturer indicates high required prices for a used product to a client. The product's value is estimated based on the Weibull distribution in the study. It decreases with the time of usage of the product. The client evaluates a motivation for discarding a product by using the following equations and determines which product is discarded. If a much lower price is indicated for a used product, it is stochastically discarded and may become a waste product. 3. Negotiation type discarding strategy: In the case where a client does not accept an order from a remanufacturer for discarding a product from the viewpoint of the required price, the client provides the remanufacturer with a possible time to dispose of the product as an offer. The product's value decreases with the time of usage of product according to the Weibull distribution, as shown in Fig. 2. The client estimates the time when the product's value equals to the required price sent from the remanufacturer by using the following equation.

rn mv n p  ' ', (4)
  O n s n p O n s n p pcr dcc t PV pcr mv , ' ', , ' ', ) (    (5)                        t PV t PV exp ) 0 ( ) ( (6)
                    0 ln ln 1 ln ln PV t PV t   (7)
The remanufacturer evaluates the offer from the client by modifying a disassembly schedule and estimates a profit by using Eq. ( 3). The remanufacturer prospectively enters into a contract with the client by accepting the offer from the client. Then, the remanufacturer can obtain a lot of used products by negotiating with the client in consideration of both the required prices from the remanufacturer and the possible time to dispose of the used products from the client. Product's value with 1.99 GB of RAM). Two suppliers, two manufacturers, a remanufacturer, and a client were implemented as agents on different six computers, respectively. In the initial conditions, the suppliers and the manufacturers had same job-shop type production schedules consisting of 5 resources and 20 contracted parts, and 10 resources and 20 contracted products, respectively. The client continuously generated 100 new orders and negotiated with two manufacturers during the experiments for about 6 hours. The manufacturers generated orders and negotiated among the two suppliers and one remanufacturer every 30 seconds of bidding time in order to generate offers for the client. Population size, crossover rate, and mutation rate of the GA were 30, 0.8, and 0.2, respectively.

Experimental results of the model with new negotiation protocol including negotiation type discarding strategy were compared with ones of the model with the previous protocol including only push and pull type discarding strategies. Ten experiments were carried out for the new model and the previous model, respectively. The experimental results are summarized in Table 1. The remanufacturer in the new model can increase the amount of reused products more than the one in the previous model. The new model can reuse about 10 % more products than the previous one. According to the rate of reused parts in new products, there are more chances to assemble the reusable parts into new products in the new model than the one with the previous model. However the remanufacturer doesn't obtain a very large profit, since it should pay the penalty charge in the case of delay in the required delivery time of usable part.

Conclusion

Previous studies proposed a closed-loop supply chain model and a negotiation protocol for increasing the amount of reused products and reducing waste products. This study improves the negotiation protocol for further increasing the reused products and reducing the waste. A remanufacturer can prospectively enter into a contract with a client by accepting the offer for possible time to dispose of product. Then, a lot of used products are economically collected by a remanufacturer through negotiation with a client in consideration of both the required prices from the remanufacture and the possible times to dispose of the used products from the client. Some experiments were carried out by using the developed simulation system for a closed-loop supply chain. Experimental results of the model with new negotiation protocol were compared with the one of previous protocol. The results show that the new protocol can reuse about 10 % more products than the previous one.

Fig. 2 .

 2 Fig. 2. Estimation of time to dispose of product based on the Weibull distribution

Table 1 .

 1 Comparison between experimental results of the two models

	Previous model	New model


Andrea Bettoni
email: andrea.bettoni@supsi.ch

Marco Cinus
email: marco.cinus@supsi.ch

Marzio Sorlini
email: marzio.sorlini@supsi.ch

Gökan May
email: gokan.may@polimi.it

Marco Taisch
email: marco.taisch@polimi.it

Paolo Pedrazzoli
email: paolo.pedrazzoli@supsi.ch

Anthropocentric Workplaces of the Future Approached Through a New Holistic Vision

Keywords: socially sustainable workplaces, anthropocentric workplace, context-aware factory

The human dimension is growing in importance in the cultural and scientific debate surrounding the arising of workplace and factory of the future visions. Having people at the centre of the factory is already recognized as a main enabler for making the most out of their skills and capacities while at the same time achieving an environment that can both motivate employed workers and attract new skilled ones. The present paper proposes a novel concept aimed at defining new socially sustainable workplaces that adapt to workers' anthropometric dimensions within worker-aware production systems that are designed and operated to capitalize on workers' skills and experience while at the same time promoting their development. Moreover it envisions the integration of the factory in the social and environmental context by promoting the creation and provision of worker-centric services that turn the factory from a society-affecting entity into an integration-promotion body.

Introduction

Companies today are declaring in their Corporate Social Responsibility (CSR) reports that they consider as primary the attention towards all the company stakeholders' and especially employees' behaviour, where the workers are referred as the company's greatest asset. However, few organizations actually treat their employees this way. In his book [START_REF] Walker | Ethics and the Employee-Centric Firm[END_REF], Walker discusses on the methodologies and approaches that an organization can implement in order to put the employee at the centre of the working environment, postulating that "only when management recognizes that the firm exists to provide an ethical environment in which employees can fully develop and apply their business skills, will the firm be positioned for true success". Royer et al. [START_REF] Royer | Employee voice and strategic competitive advantage in international modern public corporations : an economic perspective[END_REF] points out that in a strategic perspective the employees' voice is an important business component where organizations can rely on for pursuing success. Recognizing the worker as a critical resource for the enterprise success, as detailed in [START_REF] Pfeffer | Producing sustainable competitive advantage through the effective management of people[END_REF], has been the starting point for the development of structured employee-centred Human Resource Management (HRM) strategies. This vision produced the notion of employees as human capital: they collectively represent the sum of all their knowledge, skills, and abilities, as well as additional characteristics such as energy, drive and motivation they bring with them to the factory [START_REF] Cardy | Employee equity: Toward a person-based approach to hrm[END_REF]. "Knowing" the worker is thus fundamental in order to be able to foresee the value generation capabilities of the company.

According to Sinha et al. [START_REF] Sinha | Uncovering the secrets of the twenty-firstcentury organization[END_REF], the "organizations of tomorrow will be employeecentric". The positive correlation between organizations' performances and employee recognition as a critical resource in strategic management has been demonstrated by case studies and investigations on real production environments' performances [START_REF] Nayar | Employees First, Customers Second: Turning Conventional Management Upside Down[END_REF][START_REF] Ulrich | The Why of Work: How Great Leaders Build Abundant Organizations That Win[END_REF].

But, what does it mean putting the employee "at the centre" of the organization? Which are the tools supporting this shift? Which are the levers and the knowledge areas employee-centric organizations may rely on to pursue their objective?

Guided by the above mentioned research questions, this study aims at defining the new anthropocentric workplaces of the future. In this sense, Chapter 2 investigates the interaction between employee and working context, and Chapter 3 highlights the main cornerstones of these anthropocentric workplaces. Finally, Chapter 4 tries to summarize the key developments of the next years.

Employee and the Working Context Interaction

Achieving the transition to an industry where the human dimension is a key cornerstone requires, in the first place, to know each single person involved in the production processes. A reliable, holistic and accessible characterization of workers is thus called for. According to surveys of the European Commission [START_REF]European Commission: Europe 2020: a strategy for smart, sustainable and inclusive growth[END_REF][START_REF] Parent-Thirion | Fifth european working conditions survey[END_REF] quality of work and employment has four complementary dimensions: ensuring career and employment security, maintaining and promoting the health and wellbeing of workers, developing skills and competences, and reconciling working and non-working life. Accordingly four elements through which the employeeworking environment / context interaction are here identified and examined: (1) Ergonomics and Anthropometry, (2) Functional Capacities, (3) Knowledge and (4) Personal needs and private life -work balance.

Ergonomics and Anthropometry

Ergonomics encompasses the relationship between humans, machine systems, job design and the work environment. Various studies [START_REF] Eby | How to use ergonomics as a loss control tool[END_REF][START_REF] Fernberg | Tayloring the workstation to the worker[END_REF][START_REF] Griffin | Understanding ergonomics[END_REF][START_REF] Hoffer | Errors on the job can be reduced[END_REF][START_REF] Knill | Human factors engineering: An ongoing quest at at&t[END_REF][START_REF] Lindo | It's time to emphasize ergonomics[END_REF] argue that the goal of ergonomics is to enable workers to be more effective by matching the requirements and demands of the job to the abilities and limitations of the workers rather than trying to force the workers to fit the job.

The social impacts of ergonomics are obvious and empirical studies reported in [START_REF] Rowan | Ergonomics is good for business[END_REF] have proven that ergonomics in the workplace has also an impact on effectiveness and profitability, making this discipline important even from a pure economic point of view. The most obvious cause of the increasing interest in this field is the rising costs related with injuries on the workplace. In order to foster the adoption of ergonomics in manufacturing strategies it is also important to raise the perception that proper prevention measures can have positive impact on productivity and quality. The introduction of advanced technologies and automation in production has not yet been accompanied by parallel advances in ergonomics, resulting into workers' pathology that are not necessarily major accidents, but injuries deriving from repeated micro-traumas at muscoloskeletal and nervous system level [START_REF] Eby | How to use ergonomics as a loss control tool[END_REF][START_REF] Rickert | Ergonomics in the office[END_REF].

Functional Capacities

Modern ergonomics evaluation practices also consider functional capacities of the workers. In order to put a strong emphasis on the relationship between the workers' abilities and the assigned task, the analysis of ergonomics and functional capacities are kept separated.

Tasks assignment strategies and methodologies can be traced back to 1911 in Taylor's "Scientific Management" [START_REF] Taylor | The principles of scientific management[END_REF]. Taylor's principles for manual workers productivity emphasized efficient and effective object motion to ensure the best possible outcome. The object, its necessary and sufficient motion in space and time, and the manual worker's movements are integrated to achieve control over the manufacturing variables and meet the requirements for a quality product.

Approaches deriving from traditional scientific management theories require a careful and in-depth analysis of the operations and working tasks, on one side, and of worker physical capacities and characteristics on the other. In fact, physical characteristics of the worker have a meaningful impact on its performances [START_REF] Smith | The role of tacit and explicit knowledge in the workplace[END_REF].

The analysis of the matching between the worker functional characteristics and capabilities and the assigned tasks is elicited in a proper workplace design. This simultaneous consideration of worker/workplace and worker/job binomials is often at the basis of Total Quality Management [START_REF] Evans | The Management and Control of Quality[END_REF], or Business Process Reengineering methodologies, with the goal to improve working conditions and promote a sustainable working life where work environment improvement efforts are a resource for both the workplace and the individual.

Knowledge

As stated by Waitley [START_REF] Waitley | Empires of the Mind: Lessons to Lead and Succeed in a Knowledge-Based World[END_REF] "Today, the source of power has shifted from capital resources to human resources, from natural resources to knowledge resources, from position status to relationship process, and from shareowner power to customer power". Knowledge is one of the most important resource employees bring to the company, and those who want to succeed have the challenge to identify, create, share, store, and internally disseminate the employee's knowledge [START_REF] Liker | Toyota Talent: Developing Your People the Toyota Way[END_REF].

Adopting Knowledge Management tools in industrial contexts has become a necessity, and organizations need to manage these intellectual assets effectively. This is true for both big competitors and for SMEs.

Investing in KM systems is a way to facilitate the experience and knowledge flow between the employees of a firm [START_REF] Lee | The effects of entrepreneurial orientation and knowledge management capability on organizational effectiveness in taiwan: The moderating role of social capital[END_REF]. Bhattacharya et al. [START_REF] Bhattacharya | The effects of flexibility in employee skills, employee behaviors, and human resource practices on firm performance[END_REF] shows that knowledge and skills are strongly related with company performances. Proper Knowledge Management Systems have been thus adopted in various industrial contexts in order to both collect and reuse workers knowledge for the benefit of the company, using direct and indirect [START_REF] Small | Knowledge management and knowledge sharing: A review[END_REF].

Personal Needs

Finally, workers' behaviour and personal needs are rarely gathered and included in workers' profiles. These data are usually collected using traditional (e.g. questionnaire-based) means and included in ad-hoc "workers-care" initiatives or campaigns. Many social studies can be mentioned reporting results of these investigations and several tools and methodologies [START_REF] Burchell | The Great Workplace: How to Build It, How to Keep It, and Why It Matters[END_REF] are adopted especially in big companies in order to ensure workers personal wishes collection and re-use for organizational improvement.

Nowadays, many companies are trying to respond to the worker requirements enhancing the working conditions on one hand, and a sustainable work participation on the other hand. Some of these initiatives are suggested by CSR implementation strategies, where the employee is one of the (most important) stakeholders the company has to take care of. The characteristics related to the production processes, such as scheduled time, machine productivity, etc. may impose a constraint when addressing the worker personal requirements during the setting phase of the working conditions. These conditions, in fact, include schedule and workplace flexibility, autonomy and accountability, teamwork, management by objectives, strict deadlines, etc. that are all elements constrained both to processes and workers characteristics [START_REF] Frenkel | The linkage between the lifestyle of knowledgeworkers and their intra-metropolitan residential choice: A clustering approach based on self-organizing maps[END_REF].

Anthropocentric Workplaces of the Future

This chapter provides a novel concept that aims at defining new socially sustainable workplaces where the human dimension is a key cornerstone. Workers are foreseen at the centre of the factory, on the one hand, in terms of workplace adaptation and production planning, to skills, expertise and characteristics of each single worker and, on the other hand, in terms of capability to make the most out of workers' knowledge and potentials across all age groups and different roles, simultaneously fostering enhanced workers safety. Moreover, this concept promotes the vision of an effective integration of this anthropocentric factory within the social environment toward the implementation of context-aware factories that encourage and take advantage of extended services to the workers in terms of accessibility, inclusiveness, work-life balance and work satisfaction.

The main human-centric factors governing production taken into considerations are: (1) Efficiency, (2) Occupational Health and Safety with related Risk Management and (3) Effective use of workers knowledge. In this sense, evolving characteristics of each single worker in terms of age, expertise, attitudes and health conditions, imply an ever changing profile of skills and tasks, that needs to be taken into consideration in terms of work organization and workplace adaptation and in terms of capability to make the most out of workers' knowledge and potentials.

The Anthropocentric Workplace of the Future concept will lays its foundation on four cornerstone, which are: In the following subsections, a brief description of these cornerstones are provided.

KNOW

Know the Worker. Knowing the worker means to track in real time the evolving profile of the worker, through his characterization in the following four dimensions: (1) Anthropometry, a detailed picture of the worker with the most significant dimensions of the human body, (2) Functional Capacities intended as the sensorial, physical and cognitive capacities considering also age and gender related issues, (3) Knowledge resident in each worker which could be of any benefit for the factory or colleagues, (4) Personal needs of the worker, paying particular attention to aspects more related to the personal and private life of the worker such as territorial origin, nationality, family composition, physical activity, mobility, religion, leisure, etc. [START_REF] Corti | Human resource management[END_REF].

The collection of all these elements will be combined in order to create a worker profile, which is complete and changing over time.

Know the Factory. Unlike the traditional characterization of a factory which is based on production capacity, productivity, lead times and other economic and financial driven KPIs, the proposed concept aims at characterizing the factory from a worker point of view. This is done to identify and track potential interactions between workers and the elements of the working environment interacting with them. The main factory elements represented will include production KPIs, jobs/task with required skills, working shifts, organizational structure, processes, workplaces shapes and placing, intra-worker interactions and corporate services. These elements will form the basis to create a formalized representation of the factory also complemented with all the key risk factors, essential to assess the adequacy of workers' evolving conditions to the assigned jobs.

The combination of these elements will allow to create a reliable, evolving worker-centric view of the factory.

Know the Context. The environmental and social context in which factories are placed will be analyzed through stakeholder-specific relationship management approaches, deployed on the three dimensions of sustainability (economic, social and environmental). This will allow to create a comprehensive awareness and understanding of the territory and trends in which the factory is located, providing valuable inputs to a dynamic decision making process, promoting contextaware strategies and objectives.

Design & Deploy the Workplace

Data and information gathered thanks to the KNOW cornerstone represent a comprehensive, consistent and evolving knowledge base enabling the design of worker-centric, factory-conscious and context-aware workplaces. This will result into designs of effective workplaces based on: (1) worker characteristics, (2) factory requirements and (3) context/environment needs and constraints. Concrete outputs will be thus the designs of anthropocentric model workplaces addressing the needs of the specific target group "plant and machine operator" working in manufacturing production environments.

Plan the Production and Organize the Work

The KNOW knowledge base and the worker-centric workplaces designs deriving from the previous two cornerstones are taken as structured inputs for the worker-and context-aware organization and planning of production-related jobs, tasks and human resources. Methodologies and tools of this third cornerstone are enabling the valuable and dynamic integration of workers, workplaces and production requirements taking into account constraints and opportunities deriving from the factory and the contexts. The solutions and approaches allow the identification and characterization of the better performing allocation of resources to changing and evolving jobs and tasks, also including comprehensive plans for human resources management and effective training of the workforce.

Produce with context-aware factories integrated in their social environment

The last cornerstone is meant to favour and ease the integration of the workers into the social and environmental context where the factory is placed. The collected personal needs of the workers, and constraints/requirements and opportunities of the social context where the factory is placed, are both matter of this cornerstone in order to (1) minimize the environmental impact of the factory activities (identifying sustainability-enhancing strategies), (2) transforming the factory from a society-affecting entity into an integration-promotion body proactively favouring workers valuable inclusion into the social environment.

The paper presented a novel concept that places the worker at the centre of the factory by defining the next generation of socially sustainable workplaces. An analysis of the key elements for achieving these workplaces has been carried out identifying the main areas of development and the related gaps and needed improvements.

The four cornerstones at the basis of the proposed concept, also currently investigated within the European FP7 project Man-Made, have been then presented. Starting from the formalization of the knowledge concerning the worker, the factory seen from a worker's perspective and the context where the factory operates, methods and tools for anthropocentric design of the workplace and of the factory operation management at large have been identified. Finally, means for a valuable integration of the factory in the social environment through the provision of personalized services aimed at improving the balance between working and non-working life are discussed.

The piece of research described in this paper represents the starting building block for the development of specific methodologies and tools aimed at supporting the implementation of the discussed vision in real production environments. This will promote a leap towards the next level of human-factory-context balance for the factory of the future.

1 .

 1 KNOW the worker / factory / context 2. Design & Deploy the workplace 3. Plan the Production and Organize the Work 4. Produce with context-aware factories integrated in their social environment

Acknowledgement

This work has been partly funded by the European Commission through Man-Made (MANufacturing through ergonoMic and safe Anthropocentric aDaptive workplacEs for context aware factories in EUROPE) project (Grant Agreement No: FoF.NMP.2013-3 6090730). The authors wish to acknowledge the Commission for its support. The authors also wish to acknowledge their gratitude and appreciation to all the Man-Made partners for their contribution during the development of various ideas and concepts presented in this work.


Jing Shao
email: jing.shao@polimi.it

Marco Taisch
email: marco.taisch@polimi.it

Miguel Ortega Mier
email: miguel.ortega.mier@upm.es

A Proposal of Consumer Driven Framework for Enabling Sustainable Production and Consumption

Keywords: Facilitator, SPaC, indicator, framework, consumer driven

Sustainability becomes the key towards success of manufacturing industries now. Besides increasing efficiency of sustainable industrial processes, sustainable consumption becomes an important complementary strategy for making economies more sustainable gradually. Hence, the research in sustainable production and consumption (SPaC) keeps emerging and the approach of information transition became noticed as the key to promote SPaC. Therefore, there is a notable need for generating proper approach in order to achieve the goal of providing sustainable information of a product for consumers has been discussed. This paper is looking forward to support the implementation of SPaC by developing a framework aimed at providing sustainable information of a product for consumers. Aspects and attributes have been elicited, and a novel metrics of attributes integrate with life cycle has been developed. Furthermore, a conceptualized framework aimed at evaluating social and environmental performances of a product in its production phase has been developed.

Introduction

Consumers are key to drive sustainable production and they play a central role in sustainable development [START_REF]Promoting Sustainable Consumption-Good Practices in OECD Countries[END_REF]. Presently, consumers, even green consumers could not get sufficient information that enable them making greener buying decisions. Facilitator which indicates "Laws, policies and administrative procedures" has been defined in AFI framework, and it used to enable information transition from sustainable production to sustainable consumption [START_REF] Akenji | Consumer scapegoatism and limits to green consumerism[END_REF]. Facilitator is the key element in the whole system and could properly reflect consumers and other stakeholders' attitudes, and it is assured to be function well with the help of infrastructures. From literatures, many kinds of approaches have potential to play the role of facilitator and provide sustainability information for consumers. However, from a systematic review on available approaches, it is showed that in both industrial engineering and marketing science, available approaches or instruments could hardly be directly applied for consumers [START_REF] Taisch | Critical Mapping of Sustainable Index Methodologies[END_REF][START_REF] Shao | Sustainability Assessment Instruments for Consumers[END_REF]. There is a notable need for generating proper approach or strengthening availa-ble approaches in order to get the goal of providing sustainable information of a product for consumers [START_REF] Shao | A Systematic Review on Information Transition Approaches of Sustainable Production and Consumption ( SPaC )[END_REF].

One of the most possible ways of generating facilitator to achieve the goal is to measure sustainability of a product. The instrument could be generated by applying industrial engineering approach and face to stakeholders through appropriate presenting method. Indeed, in last several decades, indices are commonly used approaches for attracting attention and often simplify the problem in order to make the impact of energy consumption and environmental impacts visible in industrial engineering [START_REF] Bell | Sustainability Indicators-Measuring the immeasurable?[END_REF]. And they are beneficial for policy making and public communication in sending information of countries' performances about environment, energy, society and economy [START_REF] Amacher | Environmental quality competition and eco-labeling[END_REF] . Although it is challenging for researchers to cover all topics at the same time, it is still possible to launch by squeezing objective scope to consumers who direct relevant to buying decisions. This paper will propose a consumer driven framework for enabling sustainable production and consumption by providing sustainability performance information of a product for consumers. This framework is designed to select possible attributes which used to evaluate social and environment performance, from which companies can choose to assess sustainability for their products associated with manufacturing. We used methodology of seven steps of "Sustainability evaluation process" [START_REF] Joung | Categorization of indicators for sustainable manufacturing[END_REF] to assess sustainability and employed "Stepwise approach to development of environmental indicators" [START_REF] Olsthoorn | Environmental indicators for business: a review of the literature and standardisation methods[END_REF] to select proper indicators. After reviewing on attributes in available sustainability assessments, and considering the objective of this research, a conceptualized framework of facilitator focusing on social and environmental impact in the production phase has been generated.

Methodology

Steps of Sustainability Assessment

Indices for assessing sustainability adopt different constructing steps [START_REF] Joung | Categorization of indicators for sustainable manufacturing[END_REF][10] [START_REF] Lehni | Ecoefficiencia World Business Council for Sustainable Development Presentation at WBCSD : Progress toward Sustainability[END_REF] . In this research, the methodology adopted is the seven-step "Sustainability evaluation process" [START_REF] Joung | Categorization of indicators for sustainable manufacturing[END_REF] (Shown in Table 1). The choice was made based on its property of general applicability of generating single indicator in sustainability assessment. From previous study [START_REF] Shao | Sustainability Assessment Instruments for Consumers[END_REF], the sustainability objective has been fully discussed and well defined as: provide sustainability performance information of a product for consumers in order to make collaborative buying behavior become an incentive for greener manufacturing possible. In Step 2, even though set of indicators are chosen and decided by experts, it is a subjective process since selection of the right set of indicators de-pends on many factors, such as the type of product, type of processes, final reporting format, budget, approvals required, market, and time availability. Therefore, in this paper, we focused on step 2 "selecting indicators" and the methodology of choosing appropriate indicators will be discussed in the following section.

Top-Down Approach for Selecting Indicators

A stepwise protocol to develop appropriate sustainable indicators was proposed by Olsthoorn, X., as shown in figure 1 [START_REF] Olsthoorn | Environmental indicators for business: a review of the literature and standardisation methods[END_REF]. It is a general protocol for generating environmental indicator that starts from available data collection and then proceeding with normalization, aggregation, together with standardization. An indicator will be presented for its data users at the end. Compared to above commonly applied stepwise protocol for developing general sustainable indicator, this study focused on providing meaningful, accurate, relevant and cost-effective information for consumers. Therefore, a high emphasis has been put on research on the information needed of consumers.

The selection of key attributes is a crucial task in this study. The very first time the four basic rights which includes safety, information, choice and legal representation of consumer were declared by US President John Kennedy in 1962. Later, the rights to the satisfaction of basic needs, redress, consumer education and a healthy environment were added and adopted by The United Nations in 1985 [START_REF] Ha | Current Measures to Protect E-Consumers[END_REF]. [START_REF] Harrison | The Ethical Consumer[END_REF] have proposed some external factors that influence the growth of ethical consumer consumption-a variant of sustainable consumption [START_REF] Harrison | The Ethical Consumer[END_REF]. And "social and environmental effects of technological advance" was the first dimension of all the perspectives. Therefore, in order to promote sustainable consumption, only sustainability assessment information should be included in this framework, and furthermore, only the information on social and environmental impact of a product should be included.

Development of Life Cycle Integrated Metrics

In the field of sustainability assessment, numerous indicators were developed by researchers and practitioners. Past research on reviews of sustainability indicators from the perspective of industrial engineering are common to see [START_REF] Singh | An overview of sustainability assessment methodologies[END_REF][14][15]. Various weighting methods of composite indexes have been summarized in [START_REF] Freudenberg | Composite Indicators of Country Performance: A Critical Assessment[END_REF]. A full list of sub-categories of sustainable performance assessment of a country and involved indicators, plus their related information such as definitions, calculation methods and references were reviewed in the literature [START_REF]Indicators of Sustainable Development: Guidelines and Methodologies[END_REF]. Literatures on achievements and chal-lenges regarding measuring sustainable development were proposed by Organization for Economic Cooperation and Development [START_REF]Policy Brief: Sustainable Manufacturing and Eco-innovation: Towards a Green Economy[END_REF] .

Dimension and Aspects Comparison of Indices

From systematic review of available indicators, six publicly available indicators which associate with social and environmental performance assessment have been selected to have a detail study and analysis on [START_REF] Shao | Sustainability Assessment Instruments for Consumers[END_REF]. Table 2 shows the list of dimensions of the index. Two main streams of indicator generation could be found in the list of dimensions of indices. One stream is generated in line with the three pillars of sustainability [START_REF] Brundtland | Our common future[END_REF]. Impact of social, environmental, and economic performances have been assessed by sub-indicators. Some of them added extra dimensions, such as "well-being" (e.g., CS), or "technical aspects" (e.g., CSPI), or "cost house" (e.g., LInX), to have a complementary list of assessment measures (Reference see Appendix).

Table 2. Comparison of dimensions of index

Another stream of indicators considered life cycle assessment as an important approach when measuring the sustainability of product, so production, using and disposal phases of a product have been regarded as dimensions in this indicator, e.g., E99. In addition, G Score focuses on the production phase of a product, combine with environmental impact. F-PSI has considered both two streams of generation approach and combine sustainability dimensions with life cycle dimensions. This study adapts with definitions of themes and sub-themes in the literature [START_REF]Indicators of Sustainable Development: Guidelines and Methodologies[END_REF].

Life Cycle Integrated Metrics

In order to carry out the novel metrics integrated life cycle process, a hierarchical diagram is defined using a top-down approach. It includes Dimensions, Aspects and Attributes.

Aspects and attributes are clusted in line with five phases of life cycle of a product. Besides Production, Using and Disposal phases, Transportations between manufacturing and using, and between using and disposal phase should be included. It is suggested that, as a comprehensive framwork for faciliating sustainable consumption, above aspects and attributes should be considered. In the table 3, aspect of Nature has been listed as a feature which should be assessed through entire life cycle. It is because long term consideration is required in these attributes. In currtent state of research, focus of Consumer Driven Framework was consentrated on aspects and attributes in Production phase and attibutes impact caused in manufacturing phase (as shown in grey area).

Goal of Consumer Driven Framework

This framework is designed to integrate all the possible attributes which used to evaluate social and environment performance, from which companies can choose to assess the sustainability for their products associated with manufacturing. Further developed instrument could function well in the mechanism of sustainable consumption as a facilitator. It well connects stakeholders and infrastructure and promotes entire system moving forward.

4.2

Criteria of Developing Consumer Driven Framework

The development of consumer driven framework is decided by following five criteria that suggested for developing a tool for promoting sustainable consumption [START_REF] Shao | A Systematic Review on Information Transition Approaches of Sustainable Production and Consumption ( SPaC )[END_REF]. First of all, the framework should be capable for meeting consumers' preferences regarding its focusing scope. From the perspective of consumers, the product is the interface they are facing and should make buying decision upon. So it will be much clear if the information is measured and provided based on unit of a product. Beyond considering the content and assessment unit, requirements from consumers are more critical on their presenting format of information. The goal of making information transparency could not be achieved without appropriate format. Therefore, the last three criteria are concerning information transparency ability of the approach. Unless the framework is designed and implemented from consumers' origination, it could hardly be properly applied for consumers. Besides, weather the information is recognizable and weather it has appropriate presenting format are key features. Furthermore, consumers need comparable information regarding their green preferences in order to make greener buying decision.

Therefore, the criteria of consumer driven framework consist of: Additionally, it considered applicability of attributes in the process of developing Consumer Driven Framework.

Structure of Consumer Driven Framework

The selection of the dimensions of interest to be included in the final model has been based on the literature analysis that led into a preliminary list of associated attributes.

This preliminary consumer driven framework has two dimensions which indicate environmental impact and social impact. Aspects of Nature, Energy Using and Material Using are included in the dimension of environmental impact. Dimension of social impact has aspects of Human and Company Image. Detail attributes are listed in table 4.

Conclusion

This research proposed a framework that aimed at evaluating social and environmental performances of a product in its production phase to help consumers to access the sustainability performance information of a product, and then enhance greener buying decision. The research piece presented in this paper is going to be developed further by introducing detailed formulas for indicators and validating through case studies. Therefore, the proposed framework contributes to the literature in the field development of facilitator in SPaC. The final proposal is a supporting tool for practitioners who can choose to assess sustainability for their products associated with manufacturing based on this framework. A fine-tuned version is thus expected to be released in the near future.

Fig. 1 .

 1 Fig. 1. Stepwise approach to development of environmental indicators (Source: [9])

  (a) Focus on consumers' preferences; (b) Product based assessment; (c) Consumers originated; (d) Degree of recognition by consumers; (e) Degree of comparability among same type of products.

Table 1 .

 1

	7 Steps of Sustainability evaluation process (Source: [8] )
	Step 1. Set sustainability objective	Step 2. Select indicators
	Step3. Specify measurement procedures	Step4. Analyze data
	Step 5.Report	Step 6. Make managerial decision
	Step 7. Evaluate impact

Table 3 .

 3 Metrics of attributes in Consumer Driven Framework with life cycle

			Social Impact	Environmental Impact
	Production	Human :	Material:
			Employee Training	Reuse/recycling of resource (energy,
			Employee participation	material, product)
			(human right)	Raw Material Extraction
			Child labor	Specific Raw material consumption
			Working safety
				Energy Using:
			Company image:	Energy Efficiency	Nature:
			Law suit	Renewable Energy	Life cycle Air
			Local community	Specific energy consumption	Quality
	Transportation			Water Consumption
	Using		Customer health &	Fuel Production and Consumption	Regional Ozone
			safety	Maintenance Material Production	Urban Particulates
				Noise-in-use	Biodiversity and
					Habitat
					Average noise level
	Transportation			in the periphery of
	Disposal		Waste Management	plant dB(A)
				Energy Process
				Supplementary Materials
				Residual value
				Shredding
				Dismantling
	4	Development of Consumer Driven Framework

Table 4 .

 4 The proposed list of key aspects and attributes of Consumer Driven Framework

	Dimen-	Aspect	Attribute
	sion
	Envi-	Material	Reuse/recycling of resource (energy, material, product)
	ronmen-	Using	Raw Material Extraction
	tal		Specific Raw material consumption
	Impact	Energy	Energy Efficiency
		Using	Renewable Energy
			Specific energy consumption

Acknowledgement. This research is partly conducted within the framework of the European Doctorate in Industrial Management (EDIM) which is funded by The Education, Audiovisual and Culture Executive Agency (EACEA) of European Commission under Erasmus Mundus Action 1 programmes. Furthermore, this research is partly funded by the European Commission through the PREMANUS Project (FoF-ICT-2011.7.3: Virtual Factories and Enterprises, www.premanus.eu).

Appendix: List of indicators and references


Rossella Luglietti
email: rossella.luglietti@polimi.it

Federico Magalini
email: federico.magalini@polimi.it

Marco Taisch
email: marco.taisch@polimi.it

Jacopo Cassina
email: jacopo.cassina@holonix.it

Environmental Impact and Cost Evaluation in remanufacturing business decision support

Keywords: LCA, Remanufacturing, End of Life, Recycling, ICT

The research implements a business decision support system to evaluate environmental and economic implications for different end of life alternatives strategies. The case study described in the paper is the evaluation of end of life automotive engine. In detail, the analysis consists of the evaluation of environmental impacts and economic costs of engine remanufacturing process. In particular, will be compared three different alternatives: remanufacturing, reuse and recycling (material recovery). Thanks to remanufacturing, it is possible anyway to increase end-of-life benefits, compared with recycling, avoiding, from a life cycle perspective, the manufacturing process of new products through refurbishing or reuse, preventing at the same time certain generation of waste. Results will be shown in a bi-dimensional graph displaying the three alternatives with their economic revenue and environmental gain.

Introduction

Waste is a key environmental and economic issue and a growing problem. The amount of waste generated in Europe continues to rise each year; approximately 3 billion tons of waste are thrown away in the European Union annually. This amounts to about 6 tons of solid waste for every European [1].

On this scenario, waste management is going more and more an important part of European business. Good practices will increase the benefits from waste collection. In fact, the improvement of separated collection will increment the secondary raw materials sold, and the benefit in terms of profits and environmental gain.

The connection between economic growth and environmental impacts associated with waste generation is a key objective of the EU's revised Waste Framework Directive (Directive2008/98/EC). The policy of European Commission is to reverse the waste growth. The European legislation introduced the waste hierarchy within the EU's Sixth Environmental Action Programme [2], developing the waste overturned pyramid, which identifies waste management priorities. The pyramid base represents the best option, identified by prevention, and the vertex expresses the worst choice in terms of environmental gain [START_REF]Being wise with waste: the EU's approach to waste management[END_REF]. The European Commission promotes waste recovery as key strategy to reduce the quantity of waste for disposal and saving natural resources, in particular by reuse, recycling, composting and recovering energy from waste. From the European perspective, remanufacturing includes the activities to prepare for reuse of products.

It was recognized that the identification and selection of the best end-of-life options should regard to environmental and economic effects, taking into account scientific and technological progress and life cycle analyses to be further developed. Reuse and material recovery should be considered preferable where and in so far as, they are the best environmental options [START_REF]Directive of the European Parliament and of the Council on Waste from Electrical and Electronic Equipment (WEEE)[END_REF].

Remanufacturing is a standardized industrial process of bringing used products, worn or non-functional, to "like-new" functional state with equivalent condition and function than the new original one. Remanufactured parts have the same as the warranty required for new products equivalent. Remanufacturing is going to be a common practice, especially for complex products with high value to implement the waste prevention. At the moment, the major sectors where remanufacturing is developed are: automotive, ICT equipment, ink and toner, medical, precision and optical equipment, pumps and compressors and tires [START_REF] Walsh | Remanufacturing in Europethe Business Case[END_REF].

The research presented is being developed in the context of the PREMANUS project, a co-funded project by the European Union under the ICT theme of the 7th framework program for R&D. Part of the project is focusing on development of a business decision support system to take the best selection, considering both the economic aspects and environmental implications, for different end of life alternatives of complex products. In detail, this research is focused on remanufacturing of automotive light engine, one of the three case applications developed under the PREMANUS project.

The eco-efficiency diagram is introduced (Fig. 1), allowing the interaction between economic and environmental dimensions into the decision making process. On the Yaxis of the diagram it can plot an economic indicator (in this case €) for the total costs occurring during the remanufacturing process. The X-axis represents the environmental indicator (it has been chosen the equivalent CO2 emission).

Literature review

The aim of this research is to evaluate the environmental impacts of end of life alternatives. The innovative approach developed in many studies during the last years, is the integration of economic dimension to the environmental one. The meaning of Sustainability includes the three dimensions: environmental, social and economic. The social sustainability has been excluded because is a qualitative dimension, and it does not have a bearing into the remanufacturing scenario. Might be interested, in the future, analyzing this aspect in waste management strategy. For the environmental evaluation, the methodology utilized is the Life Cycle Assessment, in a streamlined form. Life Cycle Assessment (LCA) is a structured, comprehensive and internationally standardized method. It quantifies all relevant emissions and resources consumed and the related environmental and health impacts and resource depletion issues that are associated with the entire life cycle of any products or services [START_REF]ILCD Handbook. Analysis of Exixting Environmnetal Impact Assessment Methodology for Use in Life Cycle Assessment[END_REF]. It has been implemented a simplified approach to include streamlining into the whole LCA framework. The methodology is compliant with the Society of Environmental Toxicology and Chemistry (SETAC) guidelines that, on July 1999 [START_REF] Weitz K | Streamlined Life-Cycle Assessment: a Final Report from the SETAC North America, Streamlined LCA Workgroup[END_REF], established a list of streamlined part of a full LCA. Their investigation starts identifying a level of efforts required for each study, with two different approaches. In the first case, they introduce streamlining within the existing LCA framework, and in the second alternative streamlining approaches based on life cycle concepts. The purpose of these guidelines is to:

• redefine streamlining as an inherent part of any LCA approach;

• describe various ways that streamlining LCA has been attempted and investigated and the possible implications in different decision making contexts.

A small and simple Life Cycle Inventory has been developed, embracing the potential impacts for the inputs and the processes included into the analysis; Manmek S. and Kara S. [START_REF] Manmek | Application of the Simplified Life Cycle Inventory for a Product Life Cycle[END_REF] have chosen a similar approach. They presented a Simplified Life Cycle Assessment (SLCA) methodology to assess the environmental impacts, which are incurred during the life cycle stages of a product. The life cycle stages included into the work are materials, production processes, usage, transportation and end of life stages. The LCI has been applied with the case study of photocopier machine, and they have verified with a full LCA. About the costs evaluation, the literature review shows the many differences between system boundaries and user goal. Richard Wood and Edgar G. Hertwich introduce the LCC as possible indicator in economic evaluation [START_REF] Wood | Economic modelling and indicators in life cycle sustainability assessment[END_REF]. They have related the potential contradictions in system boundary to an environmental LCA. Further, it has an inherent contradiction between user goals (minimization of cost) and social goals (maximization of value adding), and has no clear application in a consequential setting.

In the context of PREMANUS project, a literature review about product remanufacturing research has been done. It has been investigated potentials interesting studies about environmental benefits of remanufacturing, to compare the methodology used in this research and the one used by others authors. In details, some studies about environmental evaluation have been analyzed; Some authors introduced a comparison between different alternatives of dismantling (e.g. recycling, reuse) and new products.

In particular, it has been analyzed the study of Amaya J. et al. about the remanufacturing of truck injector [START_REF] Amaya | Environmental Benefits of Remanufacturing: the Case Study of the Truck Injector[END_REF]. The study shows how to established environmental as-sessments for remanufactured products life cycles and how to compare them to environmental assessments for new products life cycles. This work tried to include the consideration of multiple cycles of remanufactured and reused products, to evaluate the comparison within new products. A similar approach has been used by Sutherland J. et al. that has been analyzed a comparison of manufacturing and remanufacturing energy intensities with application to diesel engine production [START_REF] Sutherland | A Comparison of Manufacturing and Remanufacturing Energy Intensities with Application to Diesel Engine Production[END_REF]. They developed a procedure to standardize the benefits of remanufacturing. Their research determines the energy intensity and benefits of remanufacturing as compared to new manufacturing.In extensive literature research carried out on the broader remanufacturing field, only few papers have been found with a focus on LCA and remanufacturing of automotive engines comparing different end of life strategies. In none of those papers a specific link between environmental and economic implications was described. At the end, the innovation of this work is to exploit the results and the methodology in a software platform, using the life cycle data specific for a physical product. In this way, the results might be more accurate.

Research application

The research defines the total benefit of end of life alternatives in term of environmental gain and economic profit. Within the PREMANUS project three industrial cases have been analyzed: the automotive engine and wind turbine gearbox remanufacturing strategy, and WEEE (Waste of Electric and Electronic Equipment) management. At this stage, the automotive engine case study has been fully implemented. As described in the Introduction the results will be expressed in a bi-dimensional graph to discover the best solution in terms of Environmental gain and economic profits.

Methodology

The methodology is different considering the environmental measurement and economic aspect.

About environmental dimension, the Life Cycle Assessment methodology has been applied in a streamlined form [START_REF] Weitz K | Streamlined Life-Cycle Assessment: a Final Report from the SETAC North America, Streamlined LCA Workgroup[END_REF]. As mentioned in ISO 14044 the Life Cycle Assessment has been divided in 4 phases [START_REF]Environmental Management -Life cycle assessment -Requirements and guidelines[END_REF]:

1. Goal and Scope definition; 2. Life Cycle Inventory; 3. Life Cycle Impact Assessment; 4. Life Cycle Interpretation.

During the goal and scope definition the functional unit and system boundaries has defined. The research outlines the environmental implication about one engine sent to remanufacturing plant.

The Fig. 2 shows the system boundaries analyzed during the evaluation. The section investigated in this research is the product End of Life, and in particular, the remanufacturing process and the material recovery. In detail, a complex product can be undergone the remanufacturing process or reused as such; in addition, the components can be sent to material recovery, in some case only one of this option is acceptable, and the practitioner can follow only one direction. Each of those alternatives makes benefits (except the dispose). The phases not included into the analysis are in grey, and the area focus on the research is in bold.

As it can see in Fig. 2 remanufacturing and reuse allow to avoid the impacts related to "beginning of life", like the extraction of raw materials and manufacturing phase. In the reduction of environmental impacts point of view, this situation is very important, because one of the most impacts is caused by the engine production and in particular by the raw materials extraction and procurement. An important difference between reused products and remanufactured ones is the life expectancy. As introduced before, the remanufacturing process bring a used or non-functional good to a "like new" functional one. In this case, a core may have a new complete residual life (around 20 years, or a certain mileage). Instead, a used engine, put back on the market, has a lower life expectancy depending on its previous life (e.g. mileage).

The material recovery allows to save raw materials, and in this way to reduce the impacts caused by extraction.

Results

Fiat operates a remanufacturing plant, which manages all types of FIAT Group engines every year. As analyzed during the case study, around 45% are light engine, the type under discussion. Some simplifications, particularly in terms of engine components, have been considered in the research. In specific, only the major following components have been considered: cylinder block, cylinder head, pistons, connecting rods (conrods), crankshaft, flywheel, camshaft, turbo.

A core, after disassembly and washing process, is inspected and each component undergo a specific treatment. In some cases it may be necessary add new components, for example if the engine is incomplete, or if some components are useless. During the process the input considered for each step are electricity, compressed air, water consumption, oil consumption.

In Fig. 3, energy consumption and other resources used for each option, expressed in percentage, and the distribution of energy consumption during each phase for the three options are displayed. In the graph on the left, some activities have the same energy consumption for the three options. At this stage of life cycle, the remanufactured engine cause higher energy consumption than the others options. In detail, only the remanufacturing process use resources in addition to electricity and water. The figure on the right shows the results in percentage to highlight the absorption of energy during the process.

Only for remanufacturing process accurate information has been used, about data to evaluate the processes avoided (e.g. manufacturing phase and raw material extraction) qualitative and statistical information have been extract from database Ecoinvent. Once listed the input interested to the remanufacturing process impact assessment can be evaluated. As explained in the previous section, the environmental performance indicator chosen for the analysis is equivalent CO2 emission, with the carbon footprint methodology [START_REF]Greenhouse gases --Carbon footprint of Products --Requirements and Guidelines for Quantification and Communication[END_REF], with Simapro 7.3. This indicator expresses the life cycle assessment limited to emissions that have an effect on climate change [START_REF]Carbon Footprint -What it is and How to Measure it[END_REF]. Table 1 shows the results of analysis displayed as kilograms of equivalent CO2 emissions (Carbon footprint) and Euros (€). Results include the impacts of the entire process conducted into the remanufacturing plant. As can be seen from the results, the remanufacturing causes more impacts during the process; the main reason is the resource consumption during the process. From life-cycle perspective, anyway remanufacturing leads to more environmental benefits compared to the other end-of-life alternatives. Indeed, the recycling processes have an important impact that reduce the benefits linked to avoided impacts about raw materials extraction. The difference between reuse and remanufacturing is mainly linked to the avoided manufacturing phase of new product. For reused goods, those benefits are anyway lower than remanufactured ones. From the economic perspective, materials recovery scenario revenues generated selling raw materials have been calculated. The final value shows that remanufacturing is the best solution, and a reused engine has more benefits compared to material recovery scenario. As described in the previous sections results are shown in a bi-dimensional graph (Fig. 4); in this way, it is possible see the difference of each option in term of environmental impacts and costs. This visualization allows decision makers to combine the two dimensions (environmental and economic) setting their own priorities. Results may be different for different products. Indeed, this model will be used in a business decision support system to evaluate the three options into the remanufacturing plant of FIAT Group. As described in the previous sections the algorithm works with defined input, which will change with the life cycle data of the engine. Each core and its components will follows these three paths and the results will change on the graph.

Fig. 1 .

 1 Fig. 1. Example of Eco-efficiency diagram.

Fig. 2 .

 2 Fig. 2. Product life cycle flow.

Fig. 3 .

 3 Fig. 3. Resources consumption reported in percentage for each activity and energy consumprtion for each options during the process phases.

Fig. 4 .

 4 Fig. 4. Eco-efficiency diagram.

Table 1 .

 1 Impact assessment of three end of life options expressed in kilograms of equivalent CO2 emission.

	Results	Reuse	Remanufacturing	Material recovery
	kg CO2 eq. treatment process	561	10.920	502
	kg CO2 eq. for recycling process			337.154
	kg CO2 eq. avoided manufactur-ing [10]	28.978	72.446
	kg CO2 eq. avoided raw materi-als extraction	640.719	640.719	640.410
	Benefits	-669.137	-702.245	-302.754
	Revenue selling materials			€ 108,46
	Steel			€ 5,17
	Cast iron			€ 34,85
	Aluminum			€ 68,44
	Revenue selling engine	€ 612,00	€ 2.562,00
	Operations costs	€ 43,47	€ 263,46	€ 158,20
	Energy consumption	€ 3,91	€ 24,85	€ 3,50
	Workforce costs	€ 39,56	€ 238,60	€ 154,71
	Total revenues	€ 568,53	€ 2.298,54	-€ 49,75

Acknowledgment.

Thanks to CRF (Centro Ricerche Fiat), which has supplied the data about remanufacturing process. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 285541.