Elkafi Hassini

Multi-site production planning integrating procurement and distribution plans in multi-echelon supply chains: an interactive fuzzy goal programming approach

Motivated by a real case of an automobile company, this study proposes a multi-objective, multi-site production planning model integrating procurement and distribution plans in a multi-echelon supply chain network with multiple suppliers, multiple manufacturing plants and multiple distribution centres. The model incorporates four important conflicting objectives simultaneously: minimisation of the total cost of logistics, maximisation of the total value of purchasing, minimisation of defective items and minimisation of late deliveries subject to some realistic constraints. Due to the imprecise/fuzzy nature of the objectives’ aspiration levels and some critical data, an interactive fuzzy goal programming formulation is first developed. Then, a novel fuzzy approach is proposed to convert the FGP model into an auxiliary crisp formulation to find an efficient compromise solution. The proposed model and solution method are validated through some numerical tests. Computational results indicate the practicality and tractability of the proposed model and also the superiority of the proposed auxiliary crisp formulation in contrast to the current alternative fuzzy approaches.

Consignment and vendor managed inventory in single-vendor multiple buyers supply chains

In this paper we model a consignment (CS) and vendor-managed inventory (VMI) policy for a single vendor and multiple buyers supply chain with known demand. We study three vendor–buyers partnerships: (i) the vendor and the buyers act independently, (ii) the vendor enters in a vendor-managed inventory consignment (VMI&CS) partnership with the buyers and (iii) the vendor and the buyer belong to a vertically integrated firm where a single decision maker decides about the ordering policies. We use relationships (i) and (ii) to study the benefits of the VMI&CS agreement. We provide analytical and numerical results. We find that such an agreement is more beneficial when the vendor has a flexible capacity. It is also more attractive to buyers when they have significant order costs and the vendors setup cost is not large. Finally we find that under VMI&CS the vendor will tend to make more frequent shipments with smaller lots.

Performance measurement of sustainable supply chains: a review and research questions

Purpose - – One of the hurdles to the adoption of sustainable practices across supply chains is the lack of pan-chain performance measurements and their related information and organizational structures. The authors review the literature on performance measurement of sustainable supply chains with a focus on comprehensive measures that include multiple supply chain partners as well as different sustainability aspects. The purpose of this paper is to analyze the reviewed literature and propose some research questions. Design/methodology/approach - – The authors reviewed 140 journal articles, cases and reports that appeared since 1994. Findings - – The authors classify the reviewed literature according to seven sustainability dimensions (economical, environmental, social, reputable, valuable, equitable and sustainable) as well as the type of industry and methodology used. In addition the authors synthesize the available performance measurements into a comprehensive framework that incorporates different stages of the supply chain operations and decision-making processes. Social implications - – The results of this study can be used by researchers to focus on research that may have more implications on supply chains. Practitioners can use the authors proposed performance measurement framework for developing practical and comprehensive measures for their respective industries. Originality/value - – The work is original in the way the authors integrate sustainability (seven dimensions) across the supply chain taking into account the type of operational decisions. The framework can be used by researchers and practitioners to develop practical sustainability performance measurement systems for supply chains.

Building competitive enterprises through supply chain management

Purpose – The purpose of this paper is to introduce a special issue that looks at how enterprises could build competitive advantage through supply chain management.Design/methodology/approach – The paper provides an overview of competitiveness within a supply chain framework, introduces the issue papers and summarizes their major features.Findings – Nowadays competition is increasingly between supply chains rather than individual companies. Thus, one would expect supply chain management to be a key in maintaining enterprises competitiveness. Through conceptual models and empirical studies this special issues papers demonstrate how designing and operating efficient supply chains, through the effective use of information technology, can provide enterprises with a competitive advantage.Research limitations/implications – The paper implies that enterprises can associate with a supply chain and develop a mechanism to fairly share surpluses. The papers in the special issue offer insight in to how an enterprise...

Storage space allocation to maximize inter-replenishment times

Given a set of storage spaces and a set of products, with specific space requirements and demand rates, we find the optimal product assignment that will lead to the longest time before any product is depleted. When demand rates are known with certainty, the assignment is found through the solution of a max-min integer program. When demand rates are stochastic with a common law, the assignment is found by solving an integer programme the objective of which is a non-homogeneous partial difference equation of first order. Unlike what common rules of thumb would dictate, our results show that the proportion of spaces assigned to a product is not necessarily equal to its demand frequency. Numerical computations show that employing the latter policy would result in inter-replenishment times that are about 24% shorter than the optimal solution.

Supply Chain Optimization: Current Practices and Overview of Emerging Research Opportunities

Abstract The purpose of this editorial is to introduce a special issue “Optimization and Simulation Models in Supply Chain Management” that looks at optimization and simulation applications in supply chain management. In addition to introducing the papers in this issue and summarizing their major contributions, we give a brief overview of the current practice in supply chain optimization and the prospects for future research in this field.

One-Dimensional Carousel Storage Problems: Applications, Review and Generalizations

Abstract In this paper we focus on the problems of one-dimensional storage location and order picking in a single carousel. We illustrate several applications, review the literature and list some open problems, and present a general model that includes the one-dimensional carousel storage location problem as well as other well-known combinatorial optimization problems as special cases.

A Lagrangian approach to the winner determination problem in iterative combinatorial reverse auctions

Combinatorial auctions allow allocation of bundles of items to the bidders who value them the most. The NP-hardness of the winner determination problem (WDP) has imposed serious computational challenges when designing efficient solution algorithms. This paper analytically studies the Lagrangian relaxation of WDP and expounds a novel technique for efficiently solving the relaxation problem. Moreover, we introduce a heuristic algorithm that adjusts any infeasibilities from the Lagrangian optimal solution to reach an optimal or a near optimal solution. Extensive numerical experiments illustrate the class of problems on which application of this technique provides near optimal solutions in much less time, as little as a fraction of a thousand, as compared to the CPLEX solver.

Scheduling and lot sizing models for the single-vendor multi-buyer problem under consignment stock partnership

We consider a centralized supply chain composed of a single vendor serving multiple buyers and operating under consignment stock arrangement. Solving the general problem is hard as it requires finding optimal delivery schedule to the buyers and optimal production lot sizes. We first provide a nonlinear mixed integer programming formulation for the general scheduling and lot sizing problem. We show that the problem is NP-hard in general. We reformulate the problem under the assumption of ‘zero-switch rule’. We also provide a simple sequence independent lower bound to the solution of the general model. We then propose a heuristic procedure to generate a near-optimal delivery schedule. We assess the cost performance of that heuristic by conducting sensitivity analysis on the key model parameters. The results show that the proposed heuristic promises substantial supply-chain cost savings that increase as the number of buyers increases.

Internet of things and supply chain management: a literature review

This paper explores the role of Internet of Things (IoT) and its impact on supply chain management (SCM) through an extensive literature review. Important aspects of IoT in SCM are covered including IoT definition, main IoT technology enablers and various SCM processes and applications. We offer several categorisation of the extant literature, such as based on methodology, industry sector and focus on a classification based on major supply chain processes. In addition, a bibliometric analysis of the literature is also presented. We find that most studies have focused on conceptualising the impact of IoT with limited analytical models and empirical studies. In addition, most studies have focused on the delivery supply chain process and the food and manufacturing supply chains. Areas of future SCM research that can support IoT implementation are also identified.