Santosh Mahapatra

Multiproduct, Multicriteria Model for Supplier Selection with Product Life-Cycle Considerations

In industrial purchasing contexts firms often procure a set of products from the same suppliers to benefit from economies of scale and scope. These products are often at different stages of their respective product life cycles (PLCs). Firms consider multiple criteria in purchasing such products, and the relative importance of these criteria varies depending on the PLC stage of a given product. Therefore, a firm should select suppliers and choose sourcing arrangements such that product requirements across multiple criteria are satisfied over time. The extant models in sourcing literature for evaluating and selecting suppliers for a portfolio of products have not considered this important and practical issue faced by firms. This article proposes a mathematical model that effectively addresses this issue and contributes to the sourcing literature by demonstrating an approach for optimally selecting suppliers and supplier bids given the relative importance of multiple criteria across multiple products over their PLC. The application of the model on a hypothetical data set illustrates the strategic and tactical significance of such considerations.

Hybrid (re)manufacturing: manufacturing and operational implications

Remanufacturing presents an option to recover value from used products. However, hybrid (re)manufacturing (i.e. simultaneous manufacturing and remanufacturing) is a challenge, owing to non-uniform availability and heterogeneous quality of returns. In this paper, we examine how heterogeneous quality and non-uniform quantity of returns influence the optimal production rates and inventory levels in a hybrid (re)manufacturing system that incurs costs to readjust manufacturing and remanufacturing capacities on a temporary basis. Specifically, we propose a mixed integer linear programming (MILP) based approach to obtain the optimal production plan for a specified planning horizon. We apply the proposed model to the (representative) operational data of an office equipment manufacturer to evaluate the impacts of quality of returns, quality-based segregation of returns, and capacity readjustment costs. The study provides insights into the effects of trade-offs among different operational costs in a hybrid (re)manufacturing system.

Impact of the pull and push‐pull policies on the performance of a three‐stage supply chain

We investigate the performance of two common operating policies (i.e., pull and push‐pull) for a make‐to‐stock product in an un‐capacitated, three‐stage supply chain. The pull policy operates based on periodic orders received from the immediate downstream facility. However, in the push‐pull policy, while processes upstream of the order decoupling point are managed by the push policy, the downstream processes are managed by the pull policy. Simulation experiments are conducted to examine the impact of each operating policy under a variety of experimental conditions, characterised by demand uncertainty and lead‐time variability. Our results indicate that the relative advantage of the two policies is dependent on the type of uncertainty, the level of uncertainty, the inventory control policy and the performance measures of interest. More specifically, while the push‐pull policy results in lower inventory, the pull policy yields a better fill rate. This is in contrast to the notion that the pull policy generally results in superior inventory performance. Our findings suggest that firms should carefully consider the level of uncertainty, the inventory control policy and the performance measures of interest when determining the operating policy.

Understanding environment management systems performance: an expanded empirical study

Successful implementation of Environment Management System (EMS) poses a dilemma for many managers and researchers. On one hand, there have been notable successes in the implementation of EMS systems. Yet, in spite of these successes, many firms have been unable to realise similar benefits. To address this dilemma, past studies have identified several factors contributing to the success of EMS implementation. This study builds upon these studies by presenting an expanded and integrated view of the factors that affect EMS success. Using data provided by large study into EMS implementation, the study shows that successful EMS implementation is influenced by the interaction of various factors such as scale of operation, uncertainty in the business environment, past experience of Quality Management efforts and the status of a formal EMS. The investigation improves our understanding of successful implementation of EMS and its relation with various contextual factors.

Integrated Contract and Spot Market Procurement by a Risk-Averse Buying Firm

We study the problem of optimally integrating contractual and spot market procurement sources for a risk-averse buying firm that purchases a commodity product at a specified rate over time. The sources involve deterministic and stochastic price processes, respectively. The risk-averse firm is concerned about the magnitude and uncertainty of procurement expenses. The problem is of increasing significance with the emergence of electronic markets that facilitate procurement from competitive spot (open) market. Models are developed to determine the optimal procurement policy in continuous time across the two sources for specified price and risk aversion parameters. We examine cases when the contract price parameter is exogenously specified and when it is endogenously adjusted according to the procurement policy. We show that the optimal strategy prescribes simultaneous procurement from both contract and spot market sources. The applications of the model on illustrative datasets provide insights into the relative advantages of integrating the two sources of procurement over a “pure contract” or a “pure market” procurement source.