Vildan Özkır

Modelling product-recovery processes in closed-loop supply-chain network design

Recent changes in environmental requirements have forced manufacturing operations to face a new challenge, which is to develop green strategies to design supply chains and their processes. This study describes the specific features of green supply-chain design considering end-of-life products. We propose a mixed integer linear programming model to obtain the optimal closed-loop supply-chain (CLSC) network design, in which recovery process occurs in three different ways: material recovery, component recovery, and product recovery. An extensive analysis is supported by numerical results which inform CLSC managers about the opportunities of enhancing product returns in terms of quality and quantity. To define a better CLSC strategy to increase system profitability, the volume of product returns and corresponding quality conditions should be considered in the design of a CLSC network. The numerical study provides information for us to discuss the potential benefits of product-recovery processes and the reaction of system profitability to the changes in specific CLSC parameters.

A fuzzy assessment framework to select among transportation investment projects in Turkey

Selecting the best transportation investment project (TIP) is often a difficult task, since many social, environmental and economic criteria have to be considered simultaneously. Evaluating a set of different projects, especially the best set of alternatives, portfolios, is even more complex. Pursuing the goal of selecting the best TIP portfolio, we propose a fuzzy assessment method to aid the selection process of a multi-criterion project by utilizing the concept of entropy and interval normalization procedure in a fuzzy analytic hierarchy process (F-AHP). Then, regarding this informative phase, we propose a fuzzy linear programming model to select the best TIP portfolio under uncertain cost pressure. A real case study is conducted to illustrate the efficiency of the proposed method.

Multi-criteria Evaluation to Prioritize the Organic Farm Site Using Extended Vikor Method

The aim of the present study is to prioritize the sites in Turkey that organic farming is being practiced through extended VIKOR. The problem was considered as a multi-criteria decision making problem. Among the main criteria taken into account in this paper, some are ecological, technological, economic, and risk factors with the impacts of infrastructure and local community. Then, the problem was solved by using extended VIKOR method and the prioritization of the organic farming sites was determined.