Anastasios Xanthopoulos

Optimal newsvendor policies for dual-sourcing supply chains

We propose generic single period (newsvendor-type) inventory models for capturing the trade-off between inventory policies and disruption risks in a dual-sourcing supply chain network both unconstrained and under service level constraints, where both supply channels are susceptible to disruption risks. The models are developed for both risk neutral and risk-averse decision-makers and can be applicable for different types of disruptions related among others to the supply of raw materials, the production process, and the distribution system, as well as security breaches and natural disasters. Analytical closed-form solutions are obtained and interesting managerial insights on the merit of contingency strategies in managing uncertainties and risks in dual-sourcing supply chains are discussed.

An analytical methodological framework for the optimal design of resilient supply chains

Managing risk and disruptions have emerged as issues of critical importance for todays globalised supply chains. In this work, we first provide an up-to-date taxonomy of the risks that supply chains are exposed to along with the appropriate solutions that can be employed to improve their resiliency. We then proceed by outlining an analytical methodological framework for supporting the design and operations of efficient supply chains in the new business environment by taking into account the stochasticity of various factors that can lead to disruptions. More specifically, we present a novel, to our knowledge, stochastic single period quantitative model that can assist in the decision-making process regarding the optimal security protection-based configuration of a supply chain both for single and multiple disruption cases. We obtain closed-form solutions in all cases allowing for capturing the optimal trade-off between inventory policies and supply chain protection levels. Finally, we discuss additional useful managerial insights that were obtained.

A stochastic inventory management model for a dual sourcing supply chain with disruptions

As companies continue to globalise their operations and outsource significant portion of their value chain activities, they often end up relying heavily on order replenishments from distant suppliers. The explosion in long-distance sourcing is exposing supply chains and shareholder value at ever increasing operational and disruption risks. It is well established, both in academia and in real-world business environments, that resource flexibility is an effective method for hedging against supply chain disruption risks. In this contextual framework, we propose a single period stochastic inventory decision-making model that could be employed for capturing the trade-off between inventory policies and disruption risks for an unreliable dual sourcing supply network for both the capacitated and uncapacitated cases. Through the developed model, we obtain some important managerial insights and evaluate the merit of contingency strategies in managing uncertain supply chains.

A planning optimisation framework for construction and demolition waste management

The goal of this paper is to present a new planning optimisation framework for the disassembly processes of an end-of-life (EOL) building, by explicitly taking into account, as an input, its bill of materials. When disassembling an EOL building, there is the option either to selectively deconstruct specific components and materials for reuse and recycling, respectively, while demolishing the remainder of the building, or to further continue the deconstruction process and postpone the demolition of the building for a later stage. In this context, we present a novel, integrated, decision-making model for the entire construction and demolition supply chain, starting from the optimisation of the on-site deconstruction and demolition decisions till the delivery of the collected components and materials to potential recyclers/customers and landfills. An application of the developed methodology is demonstrated via a specific case study, while the relative obtained managerial insights, regarding the behaviour of the optimal solution, are presented.

OPTIMAL SOURCING DECISIONS FOR UNRELIABLE REVERSE SUPPLY CHAINS

In this work, we propose a single period stochastic inventory decision-making model that captures the trade-off between inventory policies and disruption risks for unreliable (both uncapacitated and capacitated) dual-sourcing reverse supply chain networks. Risk-management has emerged high at the corporate agenda as globalised supply chain networks are more stretched than ever due to offshoring and thus are more exposed to disruptions, while reverse logistics has been proven to constitute a profit center. In this environment, global companies have to scrutinize especially the role of major Asian economies (with large manufacturing capacities and huge markets), while conducting their strategic procurement planning. The developed model can be applied to a number of different scenario types encompassing various instances of disruptions to the collection of the end-of-life products, of the transportation system, and of the remanufacturing yield and capacity. Analytical closed-form solutions are obtained and important managerial insights on the merit of contingency strategies in managing uncertainties for reverse logistics networks are discussed.

Design of Reverse Supply Chains in Support of Agile Closed-loop Logistics Networks

Reverse logistics is a key supply chain management discipline addressing the need for environmentally conscious manufacturing and processing of the end-of-life products. As the recovery processes are being recognised as a new value-added profit centre, the design of reverse logistics is receiving increased attention and scrutiny. In this chapter, we first present a comprehensive up-to-date literature review on the optimal design of reverse logistics and closed-loop supply chain networks. The chapter builds upon the general concepts that were developed by previous works, while extending them by presenting an integrated decision-support methodological approach for the optimal configuration of reverse supply chain networks in support of agile closed-loop supply chains. The proposed decision-making methodology provides a valuable strategic generalised model to decision makers that can be applied to various business environments. Finally, useful managerial insights regarding the implementation of the proposed solution methodology and sensitivity analysis are discussed, while specific directions for future research are provided.