Ranking green electronic supplier in auto industry using fuzzy Delphi

Article history: Received June 4, 2014 Accepted 12 October 2014 Available online October 17 2014 This paper presents a study to rank different green supplier involved in supplement of electronic parts in auto industry using fuzzy Delphi. The proposed study uses the fuzzy analytic hierarchy process for weighing criteria and VIKOR method to rank the suppliers. The results show that measures of corporate social responsibility, environmental management system, green procurement and green production are the most important criteria for green supplier selection. In addition, product quality, online tracking of orders, delivery time and quality of online information are the most important criteria for choosing a green electronic supplier. © 2014 Growing Science Ltd. All rights reserved. Green Management Supplier selection Auto industry


Introduction
Supplier selection plays essential role for the success of any businesses and there are several studies associated with supplier selection techniques (Heikkilä, 2002;Hsieh, 2002;Hsu et al., 2006).Suppliers' development is an important function within supply chain management and green supplier development is essential for effective green supply chain management (Bai & Sarkis, 2010).Awasthi et al. (2010) presented a fuzzy multicriteria technique for assessing environmental performance of suppliers.The study has three steps: The first step includes identification of criteria for evaluating environmental performance of suppliers.In step 2, the experts rate the selected criteria and the different alternatives (suppliers) against each of the criteria.They used linguistic assessments to rate the criteria and the alternatives.These linguistic ratings were then combined through fuzzy TOPSIS (Hwang & Yoon, 1981) to build an overall performance score for each alternative.The alternative with the highest score is selected as the one with highest environmental performance.The benefit of applying fuzzy TOPSIS is that it distinguishes between advantages and the disadvantage category criteria and selects solutions that are close to the positive ideal solutions and far from negative ideal solutions.Finally, the method performs sensitivity analysis to assess the effect of criteria weights on the environmental performance evaluation of suppliers.Chai et al. (2013) provided a review on papers published from 2008 to 2012 on the application of decision making techniques for supplier selection.Chang and Hung (2010) presented a study of using rough set theory to create the supplier selection model and decision-making rules.Chou and Chang (2008) presented a strategy-aligned fuzzy simple multi-attribute rating technique (SMART) method for handling the supplier/vendor selection problem from the perspective of strategic management of the supply chain (SC).The majority of supplier rating systems reach their optimal solutions without looking at firm's operations management (OM)/SC strategy.They utilized OM/SC strategy to determine supplier selection criteria and by using a fuzzy SMART they evaluated the alternative suppliers, and dealt with the ratings of both qualitative and quantitative criteria.The final decisionmaker included the supply risks of individual suppliers into final decision making.Deng and Chan (2011) presented a new Multi-Criterion Decision Making (MCDM) methodology, using fuzzy sets theory (FST) and Dempster Shafer Theory of evidence (DST) to deal with supplier selection problem.Deng et al. (2014) proposed a method, which is based on a new effective and feasible representation of uncertain information, called D numbers for the supplier selection problem.Dou et al. (2014) introduced a grey analytical network process-based technique to determine green supplier development programs, which would effectively improve suppliers' performance.They evaluated green supplier development programs with explicit consideration of suppliers' involvement propensity levels.Handfield et al. (2005) reviewed how companies could develop environmental supply chain strategies.

The proposed study
This paper presents a study to rank different green supplier involved in supplement of electronic parts in auto industry using fuzzy Delphi.The proposed study uses the fuzzy analytic hierarchy process for weighing criteria and VIKOR method to rank the suppliers.The proposed fuzzy VIKOR method of this paper is developed according to the concept of fuzzy logic and the VIKOR method, which consists of the following steps (Chen & Wang, 2008): Step 1: Create feasible alternatives, determining the evaluation criteria, and setting a group of decision makers, Step 2: Define linguistic variables and their corresponding triangular fuzzy numbers.
According to Chou & Chang (2008) studies, a nine-scale linguistic variable fuzzy number is implemented.This linguistic scales and corresponding triangular fuzzy numbers for the rating of alternatives show in Table 1.Step 3: Combine decision makers' preferences and opinions.The preferences and opinions of n decision-maker in terms of j th criterion for the i th alternative can be measured by: Step 4: Compute fuzzy weighted average and construct the (normalized) fuzzy decision matrix (D): where w represents the important weight of the j th criterion.
Step 5: Determine the fuzzy best value (FBV) and fuzzy worst value (FWV): (4) Step 6: Calculate the values: ( where S and R state the utility measure and the regret measure, respectively, and W is the weight of the j th criterion (Tong et al., 2005).In fact, S is A with respect to all criteria calculated by the sum of the distance for the FBV, and R is A with respect to the j th criterion, computed by the maximum distance of FBV.
Step 7: Calculate the values of * ; ; * ; ; : ) Here ν means the weight of the strategy of the maximum group utility (Wu et al., 2009).When v>0.5, the decision tends toward the maximum majority rule; and if v = 0.5, the decision tends toward the individual regret of the opponent.Therefore, ν is introduced as weight of the strategy of 'the majority of attributes'.Usually, the value of ν is taken as 0.5.However, ν can assume any value from 0 to 1. Rank and improve the alternatives, sort by the values S, R, and Q, in non-increasing order and reduce the gaps in the criteria and the best alternatives having the lowest value (Wu et al., 2009).

The results
The survey asks 10 experts' opinions in auto industry for filling the fuzzy Delphi questionnaire who were mostly highly educated.In addition, the study distributes the questionnaire among selected employees who worked for Saipa Group company for the second part of the survey.The survey considers seven criteria for green supply chain selection and 13 criteria for electronic green supplier selection.Table 1 and Table 2 demonstrate the summary of the description of these criteria.

(C11) IT facilities
There must be sufficient information technology facilities to help develop business.

(C12) Customer support
There must be a customer relationship management team to address any complains or concerns.(C13) Website design All websites must be designed properly such that customers could easily access required information.This includes required structure, planning activities, responsibilities, procedures, processes and resources to develop, implement, review and maintain (C3) Green production Practical efforts to achieve sustainability, which is the practical implementation of principles formulated to achieve sustainability.(C4) Green purchase Green procurement and purchasing activities that aim to ensure the appropriateness of materials purchased with the environment.(C5) Green design This includes activities that aim to minimize the environmental impacts of a product throughout its life cycle.

(C6) Pollution
This includes changes in products or production methods to minimize the environmental pollution.(C7) Green innovation Innovations in hardware or software that is related to green product innovation in energy saving, reduction of material, technology innovation, etc.
We have asked decision makers to perform pairwise comparisons.Table 3 demonstrates the results of our findings on the comparison of green supply chain criteria.As we can observe from the numbers of Table 3, all input numbers are in forms of triangular, which were shown after taking average using geometric mean.The implementation of fuzzy Delphi determines the ranking of criteria and Table 4 shows details of our findings.As we can observe from the results of Table 4, corporate social responsibility is number one priority followed by environmental management system, green purchase, green production, green design, pollution free and green innovation.Similarly, we have gathered the pair-wise comparisons for 13 criteria associated with electronic green supply chain using VIKOR method and Table 5 demonstrates the results of our survey.In Table 4 and Table 5, Weight is calculated as (lw j +4mw j +uw j )/6.

Discussion and Conclusion
According to the results of Table 5, quality of products is the most important factor followed by the capability of online tracking, delivery time, online quality information, website security and precision of order information.In addition, delivery based on the schedule, availability of electronic catalog and e-business capability are among other important criteria, which must be considered when an electronic green supplier is chosen.Based on the criteria achieved using fuzzy Delphi and VIKOR techniques, the proposed study has ranked 12 suppliers.We have also presented the results of our survey to some expert and they have confirmed our findings.

Table 1
Linguistic terms for the fuzzy rating

Table 1
Description of the criteria associated with electronic green supply chain

Table 2
Description of the criteria associated with green supply chain

Table 3
The summary of pairwise comparison of green supply chain criteria

Table 4
The summary of ranking seven criteria based on fuzzy Delphi for green supply chain criteria

Table 5
The summary of ranking seven criteria based on VIKOR method for electronic green supply chain