Mathematical Decision Model for Reverse Supply Chains Inventory

Periodica Polytechnica Social and Management Sciences, 2011

In this paper we analyze a reverse logistics inventory model investigated by . Demand of a product can be satisfied with newly manufactured and remanufactured products. The used products are collected and then returned to the manufacturer of the product. The returned items are inspected and some of the used products are disposed outside. The rate of reuse is decision variable in this model. The goal of the decision maker is to minimize the relevant costs. The aim of this paper is to reexamine the proposed model and to improve some small mistakes. First, we show that it is comfortable to determine the batch numbers of the manufacturing and remanufacturing activities, because these decision variables are integer, rather than the manufacturing and remanufacturing lot sizes. Secondly, we show that there exist optimal solutions for the batch numbers inside of the possible set, i.e. both manufacturing and remanufacturing batches could be higher than one. Thirdly, the above mentioned paper have not analyzed a case with one batch numbers both manufacturing and remanufacturing. This case can occur for some parameters.

Decision Science Letters, 2022

Nowadays, companies are recognizing their primordial roles and responsibilities towards the protection of the environment and save the natural resources. They are focusing on some contemporary activities such as Reverse Logistics which is economically and environmentally viable. However, the integration of such an initiative needs flows restructuring and supply chain management in order to increase sustainability and maximize profits. Under this background, this paper addresses an inventory control model for a reverse logistics system that deals with two separated types of demand, for new products and remanufactured products, with different selling prices. The model consists of a single shared machine between production and remanufacturing operations, while the machine is subject to random failures and repairs. Three stock points respectively for returns, new products and remanufactured products are investigated. Meanwhile, in this paper, a modeling of the problem with Discrete-Even...

Journal of Industrial Engineering

Technology is becoming pervasive across all facets of our lives today. Technology innovation leading to development of new products and enhancement of features in existing products is happening at a faster pace than ever. It is becoming difficult for the customers to keep up with the deluge of new technology. This trend has resulted in gross increase in use of new materials and decreased customers' interest in relatively older products. This paper deals with a novel model in which the stationary demand is fulfilled by remanufactured products along with newly manufactured products. The current model is based on the assumption that the returned items from the customers can be remanufactured at a fixed rate. The remanufactured products are assumed to be as good as the new ones in terms of features, quality, and worth. A methodology is used for the calculation of optimum level for the newly manufactured items and the optimum level of the remanufactured products simultaneously. The m...

IOP Conference Series: Materials Science and Engineering, 2016

The study of returned item inventory management in a closed-loop supply chain system has become an important issue in recent years. So far, investigations about inventory decision making in a closed-loop supply chain system have been confined to traditional forward and reverse oriented material flow supply chain. In this study, we propose an integrated inventory model consisting a supplier, a manufacturer, and a retailer where the manufacturer inspects all of the returned items collected from the customers and classifies them as recoverable or waste. Returned items that recovered through the remanufacturing process and the newly manufactured products are then used to meet the demand of the retailer. However, some recovered items which are not comparable to the ones in quality, classified as refurbished items, are sold to a secondary market at a reduced price. This study also suggests that the flow of returned items is controlled by a decision variable, namely an acceptance quality level of recoverable item in the system. We apply multiple remanufacturing cycle and multiple production cycle policy to the proposed model and give the corresponding iterative procedure to determine the optimal solutions. Further, numerical examples are presented for illustrative purpose.

International Journal of Applied Operational Research - An Open Access Journal, 2013

Reverse supply chain is a process dealing with the backward flows of used/damaged products or materials. Reverse supply chain includes activities such as collection, inspection, reprocess, disposal and redistribution. A well-organized reverse supply chain can provide important advantages such as economic and environmental ones. In this study, we propose a general framework and formulate a mathematical model for product return in reverse supply chain. We consider a multi- layer, multi-product for the model. The main objective of the paper is minimizing the total costs of reverse supply chain including transportation, fixed opening, operation, maintenance and remanufacturing costs of centers. To validate the mathematical model, a numerical example is solved using Lingo 9 software and the results are reported.

International Journal of Industrial Engineering Computations, 2014

The objective of this paper is to develop an integrated production inventory model for reworkable items with exponential demand rate. This is a three-layer supply chain model with perspectives of supplier, producer and retailer. Supplier delivers raw material to the producer and finished goods to the retailer. We consider perfect and imperfect quality products, product reliability and reworking of imperfect items. After screening, defective items reworked at a cost just after the regular manufacturing schedule. At the beginning, the manufacturing system starts produce perfect items, after some time the manufacturing system can undergo into "out-of-control" situation from "in-control" situation, which is controlled by reverse logistic technique. This paper deliberates the effects of business strategies like optimum order size of raw material, exponential demand rate, production rate is demand dependent, idle times and reverse logistics for an integrated marketing system. Mathematica is used to develop the optimal solution of production rate and raw material order for maximum expected average profit. A numerical example and sensitivity analysis is illustrated to validate the model.

2013

Reverse supply chain problem is one of the issues in supply chain which as well explore wastes management in relation to customer. In reverse supply chains, wastes can be recycled and reproduced and benefiting from profitability of new products which is produced from it. In this study, residuals, after transferring by customer, send to production station, sorting station and different manufacturing processes (melting, forging, clamping, painting …) for reproduction. After completion of all different manufacturing processes, several diverse products resend to customers. Here, with respect to different cost factors and also pricing concept and reproduced parts, we evaluate the mathematical model of optimizing manufacturing cost. The solution will be useful for strategic decision making in municipalities.

The mathematical modelling of reverse logistics inventory systems ignores that returned items may arrive out of sequence, i.e. with different number of remanufacturing times. Moreover, such modelling assumes that the retuned items may retain the same quality upon recovery regardless of how many times they have been previously remanufactured. This paper develops a new mathematical expression of the percentage of retuned items that can be remanufactured a finite number of times. The proposed expression is modelled as a function of the expected number of times an item can be remanufactured on its life cycle and the number of times an item can be technologically (or optimally) remanufactured based on its quality upon recovery. The model developed in this paper considers joint production and remanufacturing options. The return rate is a varying demand dependent rate, which is a decision variable with demand, product deterioration, manufacturing and remanufacturing rates being arbitrary f...

2017

A time-discrete, constrained, Linear Quadratic Gaussian (LQG) production planning problem is formulated to develop a production plan with sub-optimal levels of production and remanufacturing for a single product. With the objective to define a strategy of remanufacturing used product, estimated return rates are used to provide production scenarios based on this plan. Nowadays, specific legislation is applied to many industrial sectors regard to the return of used products. Thus, motivated by environmental factors and a shortage of raw materials, partial or total reuse of return products are a high priority on business's agenda of many companies. This paper uses an approach of literature to solve a production-planning problem of a dynamic system that includes a reverse channel, with a remanufacturing facility. It is assumed that fluctuations of demand for serviceable products are approximated by stationary normal random variables. Thus, the constrained LQG problem here considered...

2015

Increasing pressure to improve market competitiveness has pushed companies to consider the reverse supply chain because of economic and environmental benefits. Besides, legislations and directives, consumer awareness and social responsibilities towards environment are also the drivers for reverse supply chain. The process of reverse supply chains are more complicated since return flows may include several activities such as collection, checking, sorting, disassembly, remanufacturing, disposal and redistribution. Moreover, the quality and the quantity of the used products are uncertain in the reverse channel. The complexity of reverse supply chain has motivated several researchers to use System dynamics (SD) modelling techniques in the search for better strategies and policies for integrating the forward and reverse supply chains by addressing the effects of uncontrollable factors such as uncertainty of returns. The paper aims at not only proposing a methodology that provides an unde...