Preface to the Special Issue on "Mathematical Methods and Operation Research in Logistics, Project Planning, and Scheduling".

The paper authored by Alkahtani [[8]] formulates mathematical models and provides an optimization algorithm for process outsourcing, considering imperfect production with variable quantities for effective supply chain management. The WPP-SCND decision system minimizes the total supply chain (SC) cost of the system while also reducing carbon emissions associated with wood pellet SC activities. In the last decade, the Industrial Revolution 4.0 brought flexible supply chains and flexible design projects to the fore. [Extracted from the article]