Subrata Mitra

Adoption of green supply chain management practices and their impact on performance: an exploratory study of Indian manufacturing firms

Research on green supply chain management (GSCM) or sustainable supply chain management (SSCM) has attracted increased attention in recent years. Although GSCM/SSCM has been studied for developed and developing countries, there has been little information about the adoption of GSCM/SSCM practices in India. This article presents one of the earliest surveys on GSCM practices in Indian manufacturing firms. The items for the survey were developed based on the extant literature and feedback from corporates. Some of the major findings of the survey are as follows. We found that the state of adoption of GSCM practices by Indian firms was still in its infancy, the awareness of environmental sustainability was quite low among consumers, and the regulatory framework was also lacking in terms of promoting environmental sustainability. Results of data analysis showed that supplier collaboration for environmental sustainability had a positive impact on environmentally sustainable product design and logistics, which in turn was positively related to competitiveness and economic performance of the firm. We compared the results with the observations made by other researchers for developed and developing countries and provided managerial implications for the government and manufacturers as to what steps need to be taken to generate awareness towards environmental sustainability and facilitate the adoption of GSCM practices among Indian firms to a greater extent. We conclude the paper by indicating directions for future research on GSCM/SSCM.

Inventory management in a two-echelon closed-loop supply chain with correlated demands and returns

Reverse logistics or closed-loop supply chains where product returns are integrated with traditional forward supply chains have been one of the major topics of research since about the last one and a half decades. In this paper, we address the inventory management issue in closed-loop supply chains, and develop deterministic and stochastic models for a two-echelon system with correlated demands and returns under generalized cost structures. In particular, we address the following questions - Do closed-loop supply chains cost more than traditional forward supply chains? Does a higher rate of return always translate into lower demand variability and hence lower expected costs? What is the relationship between expected costs and correlations between demands and returns? Models developed and numerical examples shown in the paper reveal that although a higher rate of return and a higher correlation between demand and return reduce the variability of net demand, it may not necessarily lead to cost savings; rather the movement of costs will depend on the values of system parameters. We also quantify the cost savings in case the actual demand and return information is available at the time of decision-making. We conclude the paper by providing managerial implications and directions for future research.

Leveraging information in multi-echelon inventory systems

Abstract Decision-making in multi-echelon inventory systems is often facilitated by the availability of information. In this paper, we examine the effect of utilising demand information in a one-warehouse two-retailer system operating under periodic-review. A common and fixed replenishment interval is assumed for all stages. The lead times are deterministic, and are small compared to the replenishment interval. The warehouse does not maintain any cycle stock, i.e., as soon as replenishment arrives at the warehouse, retailers’ demands are fulfilled from the available stock. In the event of a shortage at the warehouse, two cases have been considered––emergency shipment and allocation. For both the cases, expected total cost (ETC) models have been developed, and it has been shown through numerical examples that the optimal ETC in the presence of demand information is always lower than that in the absence of demand information. It is also noted that the order-up-to level at the warehouse has to be dynamic to reap the benefits of availability of demand information.

An Algorithm For The Generalized Vehicle Routing Problem With Backhauling

The Vehicle Routing Problem with Backhauling deals with the supply of finished goods from a depot to a number of delivery points, and picking up returnable items and bringing them back to the depot using a fleet of trucks. Traditionally, the objective of the problem has been to determine the truck routes such that the total number of trucks and/or the total distance traveled/total route cost are minimized. Most of the papers available in the literature in this connection deal with problems where the linehaul (having a demand for finished goods) and backhaul (having items to be returned to the depot) customers are different, and a customer may be visited by at most one truck limiting demand and returns at a location by the capacity of the truck. In this paper, we allow the linehaul and backhaul customers to be the same leading to simultaneous delivery and pickup at a customer location, and also there is no restriction on the quantity demanded at (to be returned from) a customer location. As such a customer may be visited by more than one truck and more than once by the same truck. We developed a Mixed Integer Linear programming (MILP) formulation of the problem and a route construction heuristic. The heuristic averaged 80 ms for 110 problems tested, and in 78 of them the heuristic costs were either equal to the optimal costs or at most equal to the upper bounds on the optimal costs obtained after running the optimization package for 30 min. Optimal solutions were obtained for 28 problems at an average time of 295 ms. The heuristic could match the optimal solutions for 22 of these problems at an average time of 71 ms.

VMI for single-vendor multi-retailer supply chains under stochastic demand ☆

Abstract This paper discusses how a vendor and multiple retailers interact in a vendor managed inventory (VMI) system under stochastic demand. It is assumed that the vendor replenishes all the retailers at the same time. The vendor replenishment cycle is taken to be an integer multiple of the retailer replenishment cycle. In case of a shortage at the vendor, the available stock is allocated to the retailers on the basis of equal stock out probability. Approximate expressions for minimizing the expected total cost for the VMI system have been developed. Various levers affecting the performance of the system have been analyzed. The validity of the approximate model has been tested through simulation.

Key Success Factors, Performance Metrics, and Globalization Issues in the Third-Party Logistics (3PL) Industry: A Survey of North American Service Providers

This paper reports on a survey of North American third-party logistics (3PL) service providers. Although current research on 3PL provides valuable insights into the 3PL industry, it is primarily descriptive in nature and does not explore the underlying relationships among several factors and key issues related to the industry. This paper presents an exploratory study of the North American 3PL industry in terms of the key success factors, performance metrics, and globalization issues. Respondents to the survey are categorized based on their ratings of key success factors, and the differences in perceptions among categories are highlighted. Also, the factors with respect to which respondents are significantly underperforming are identified. Importance of the key success factors for various performance metrics is established through dependency relationships, which provide a guideline to managers for allocation of scarce resources. Factors responsible for growing globalization, important issues in connection with setting up 3PL operations in a foreign country, and growth strategies adopted by 3PL firms are also analyzed from the point of view of the respondents. Finally, the contribution to logistics research, implications of the survey findings for logistics managers, and directions for future research on 3PL are presented in the concluding section.

Optimal pricing and core acquisition strategy for a hybrid manufacturing/remanufacturing system

Remanufacturing is one of the product recovery options where the quality of used products (cores) is upgraded to ‘as-good-as-new’ conditions. In this article, we consider a monopolist firm selling new and remanufactured products to quality-conscious primary customers and price-sensitive secondary customers, respectively, with one-way substitution, i.e. some primary customers may substitute new products by remanufactured products while secondary customers can never afford to buy new products. We develop economic models under two scenarios – when the supply of cores is unconstrained and when manufacturers have to procure cores at an acquisition price. The major observations of the article are as follows. A firm is better off when there is no constraint on the supply of cores. Even when cores have to be acquired at an acquisition price, the profitability is higher than that when the firm does not engage in remanufacturing activities. When a larger number of primary customers replace new products with remanufactured products, there is partial cannibalization of new product sales; however, the combined market share and profitability of the firm increase. When core supply is constrained and customers are less sensitive to core prices, the limited supply of cores may render remanufacturing an infeasible option for the firm. Therefore, firms should not only generate awareness among primary customers to buy remanufactured products, but also step up efforts to ensure a steady supply of cores. We conclude the article with managerial implications and directions for future research.

The mediating effect of logistics integration on supply chain performance : A multi-country study

Purpose – The purpose of this paper is to analyze the impact of individual logistics-related factors, namely, supplier involvement (SI), length of supplier relationship (LSR), use of information technology (IT), and logistics integration (LI) on a firms supply chain performance (SCP) and test for the mediating effect of LI in a multi-country survey conducted in Brazil, Korea and India. The paper also develops a composite variable, supply chain competency (SCC), as an overall measure of the quality of a firms supply chain and demonstrate its effect on a firms SCP. Design/methodology/approach – The research methodology was based on designing and administering a survey instrument. Data collected from 187 organizations in Brazil, Korea and India were analyzed using the partial least squares structural equation modeling methodology. Findings – Results show that for the combined data, the direct effects of SI, LSR and IT on SCP are insignificant while LI has a very significant direct effect on SCP. On the ot...

Application of graph search and genetic algorithms for the single machine scheduling problem with sequence-dependent setup times and quadratic penalty function of completion times

In this paper, we consider the single machine scheduling problem with quadratic penalties and sequence-dependent (QPSD) setup times. QPSD is known to be NP-Hard. Only a few exact approaches, and to the best of our knowledge, no approximate approaches, have been reported in the literature so far. This paper discusses exact and approximate approaches for solving the problem, and presents empirical findings. We make use of a graph search algorithm, Memory-Based Depth-First Branch-and-Bound (MDFBB), and present an algorithm, QPSD_MDFBB that can optimally solve QPSD, and advances the state of the art for finding exact solutions. For finding approximate solutions to large problem instances, we make use of the idea of greedy stochastic search, and present a greedy stochastic algorithm, QPSD_GSA that provides moderately good solutions very rapidly even for large problems. The major contribution of the current paper is to apply QPSD_GSA to generate a subset of the starting solutions for a new genetic algorithm, QPSD_GEN, which is shown to provide near-optimal solutions very quickly. Owing to its polynomial running time, QPSD_GEN can be used for much larger instances than QPSD_MDFBB can handle. Experimental results have been provided to demonstrate the performances of these algorithms.

A framework for research on green supply chain management

The literature on sustainable/green supply chain management (SSCM/GSCM) has been non-uniform in terms of defining constructs, variables, and causal relationships among constructs. This article reviews the impact of SSCM/GSCM on firm performance with a view to identifying the most commonly used practices and proposing new constructs, variables, and construct relationships by drawing from the literature on SSCM/GSCM, reverse logistics, closed-loop supply chains, and strategic management. This article also builds a conceptual framework, grounded in theory, linking GSCM practices with firm performance, and presents propositions that may be tested in future studies on SSCM. Finally, implications of this research for practitioners and researchers are highlighted.