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  • Emergency Evacuation Planning in Natural Disasters Under Diverse Population and Fleet Characteristics

    Baou, E., Koutras, V., Zeimpekis, V., Minis, I.

    Accepted for publication in the Journal of Humanitarian Logistics and Supply Chain Management, Publication date 3 December 2018

     

    Abstract:

    Purpose – The purpose of this paper is to formulate and solve a new emergency evacuation planning problem. This problem addresses the needs of both able and disabled persons who are evacuated from multiple pick-up locations and transported using a heterogeneous fleet of vehicles.
    Design/methodology/approach – The problem is formulated using a mixed integer linear programming model and solved using a heuristic algorithm. The authors analyze the selected heuristic with respect to key parameters and use it to address theoretical and practical case studies.
    Findings – Evacuating people with disabilities has a significant impact on total evacuation time, due to increased loading/unloading times. Additionally, increasing the number of large capacity vehicles adapted to transport individuals with disabilities benefits total evacuation time.
    Research limitations/implications – The mathematical model is of high complexity and it is not possible to obtain exact solutions in reasonable computational times. The efficiency of the heuristic has not been analyzed with respect to optimality.
    Practical implications – Solving the problem by a heuristic provides a fast solution, a requirement in emergency evacuation cases, especially when the state of the theater of the emergency changes dynamically. The parametric analysis of the heuristic provides valuable insights in improving an emergency evacuation system.
    Social implications – Efficient population evacuation studied in this work may save lives. This is especially critical for disabled evacuees, the evacuation of whom requires longer operational times.
    Originality/value – The authors consider a population that comprises able and disabled individuals, the latter with varying degrees of disability. The authors also consider a heterogeneous fleet of vehicles, which perform multiple trips during the evacuation process.
    Keywords Disaster relief logistics, Emergency evacuation planning, Evacuation of disabled persons
    Paper type Research paper
     
    Post date: Tuesday, July 16, 2019 - 12:27
  • MELOGIC PROJECT: ESHFP input data and solution for a large scale problem

    The following tables present the necessary data in terms of a) demand points, b) the available fleet of vehicles for supplying consumable and non-consumable provisions to civilians and intervention groups at their cites and c) the supply point providing the necessary commodities for a large scale instance of the ESHFP:

    ESHFP input data and solution for a large scale problem

    Post date: Friday, March 1, 2019 - 09:35
  • A Strategic Model for Exact Supply Chain Network Design and its Application to a Global Manufacturer

    Arampantzi, C., Minis, I., Dikas, G.

    Accepted for publication in the International Journal of Production Research, 2018

    Abstract:

    This paper presents a comprehensive model that captures significant strategic decisions involved in designing or redesigning high-performance supply chains from the perspective of the manufacturer. The problem considers deterministic demand by multiple clients, for multiple products, over the periods of a long-term horizon. The design decisions involve selection of suppliers, establishment or resizing of production facilities and distribution centres, possible subcontracting of related activities, and selection of transportation modes and routes. The problem is formulated by a Mixed Integer Linear Programming model. Its objective is to minimise the overall costs  associated with procurement, production, inventory, warehousing, and transportation over the design horizon. Appropriate constraints model the complex relationships among the links of the supply chain. The proposed model has been applied to a large case study of a global manufacturing firm, providing valuable insights into the transformation of the firm’s current supply chain network, as well as into the potential of the proposed approach.
     
    Keywords: Supply Network, Supply Chain Design,  Global Supply Chain, Mixed Integer Linear Programming, Operational Research
     
    Post date: Tuesday, July 17, 2018 - 11:34
  • Load Transfer Operations for a Dynamic Vehicle Routing Problem with Mixed Backhauls

    Ninikas, G., Minis, I.

    Journal on Vehicle Routing Algorithms, vol. 1, pp. 47 – 68, 2018

    Abstract:

    We consider a dynamic vehicle routing problem with mixed backhauls (DVRPMB) that seeks to plan, in the most efficient way, the delivery of dynamic pickup orders that arrive in real time, while a predefined plan of serving static delivery orders is being executed. Maintaining the original assignment of delivery orders to vehicles may limit system performance, since the changes in the system state caused by the arriving dynamic orders may grant re-assignments of such orders advantageous. Thus, in this paper, we introduce and solve a variant of DVRPMB that allows orders to be transferred between vehicles during plan implementation. We refer to this problem as the DVRPMB with load transfers (DVRPMB-LT). Since the problem is solved with periodic re-optimization, we focus on the underlying optimization problem, develop an appropriate model using an arc-based formulation, and compare the exact solutions to the ones of the corresponding problem that does not allow transfers. Furthermore, we develop a practical heuristic framework to address the complexity of DVRPMB-LT and solve cases of practical relevance. Subsequently, we employ the proposed framework to solve and analyze the full dynamic problem.

    Keywords: Dynamic Vehicle Routing, Re-optimization, Dynamic Pickup and Delivery, Load Transfers, Dynamic Pickup and Delivery with Transshipments

     

    Post date: Tuesday, July 17, 2018 - 11:32
  • Scheduled Paratransit Transport Enhanced by Accessible Taxis

    Dikas, G., Minis, I.

    Accepted for publication in Transportation Science, 2017

    Abstract

    In this paper we propose and study a new paratransit transportation system that integrates accessible taxi (or private hire) services, the most widely used form of disabled transport, with semiflexible public bus services that deviate from their nominal route to provide door-to-door transport. The scope of this system is to serve all paratransit orders received and minimize the overall transport cost under practical service quality imperatives. The proposed system and its design aspects are studied by modeling the related planning problem as a mixed integer-linear program. The program incorporates important cost and service-level considerations, and it is solved to optimality by a new exact branch-and-price approach that leverages two types of subproblems, one per mode. An extensive experimental study has been performed to (a) assess the advantage of integrating the two modes, (b) assess the efficiency of the proposed solution method, and (c) provide system design guidelines for achieving an appropriate balance between system operating costs and service quality.
     
    Keywords: Demand Responsive Transit Systems, Paratransit Systems, Door-to-Door Bus Services
    Post date: Tuesday, July 17, 2018 - 11:25