Greedy-search-based multi-objective genetic algorithm for emergency logistics scheduling

https://doi.org/10.1016/j.eswa.2013.10.026Get rights and content

Highlights

  • GSMOGA combines the advantages of the greedy search method and MOGA.

  • GSMOGA is able to quickly generate a number of feasible solutions.

  • GSMOGA arranges schedules (feasible solutions) based on multi-depot and multidemand.

  • GSMOGA reveals what resources are required and acquired at demand and supply point.

  • GSMOGA is capable of arranging routing schedules for each form of transport.

Abstract

To enable the immediate and efficient dispatch of relief to victims of disaster, this study proposes a greedy-search-based, multi-objective, genetic algorithm capable of regulating the distribution of available resources and automatically generating a variety of feasible emergency logistics schedules for decision-makers. The proposed algorithm dynamically adjusts distribution schedules from various supply points according to the requirements at demand points in order to minimize unsatisfied demand for resources, time to delivery, and transportation costs. The proposed algorithm was applied to the case of the Chi–Chi earthquake in Taiwan to verify its performance. Simulation results demonstrate that under conditions of a limited/unlimited number of available vehicles, the proposed algorithm outperforms the MOGA and standard greedy algorithm in ‘time to delivery’ by an average of 63.57% and 46.15%, respectively, based on 10,000 iterations.

Introduction

The emergency logistics scheduling problem (ELSP) deals with the need to identify, inventory, dispatch, mobilize, transport, recover, demobilize, and accurately track human and material resources in the event of a disaster. Rapid response is the most critical concern in emergency logistics. Despite the wealth of research in this area, relief efforts in the northeast area of Japan devastated by the 311 earthquake were delayed by 10 days. The main problem was a lack of planning in accordance with existing road conditions and the distribution of available resources.

Most previous studies have adopted integer and linear programming to solve such problems, using a single objective or a weighted sum of objectives. However, this approach tends to be limited in real-world situations, which typically presents multiple conflicting objectives. Furthermore, this approach tends not to provide detailed routing schedules. This paper proposes a novel greedy-search-based multi-objective genetic algorithm (GSMOGA) focusing on two requirements: (1) dispatching relief resources sufficient to satisfy the requirements at all demand points; (2) the transport of relief resources with minimum delay and transportation costs. GSMOGA is far more effective than typical local search methods, such as Tabu, thanks to its incorporation of a greedy search protocol followed by the encoding sequence of chromosomes using MOGA. The resulting output is a diverse selection of routing schedules without the need for a time-consuming local search process. GSMOGA is a hybrid method combining the advantages of greedy search with those of MOGA.

The remainder of the paper is organized as follows. In Section 2, we review the literature related to emergency logistics planning. The definition of the ELSP and its essential objective functions is described in Section 3. In Section 4, we propose the algorithm used to map out optimal transport routes and maximize the delivery of resources in the minimum time at the minimum cost. Experimental results depicting two scenarios are presented in Section 5. Conclusions and considerations for future work are presented in Section 6.

Section snippets

Literature review

Solutions to the ELSP differ according to environment, population distribution, transportation networks, relief requirements, and geographic situation. In addition, the services required for the provision of food, facilities, human resources, and transportation must be taken into consideration in the design of a dispatch schedule. A number of algorithms have been proposed to overcome the difficulties associated with ELSP: Dynamic integer linear programming (Sheu, 2007), goal programming (

Problem definition

Section 3.1 presents definitions of the presented notation. The formulation of the problem is outlined in Section 3.2 (see Fig. 1).

The proposed algorithm

The proposed GSMOGA integrates the speed of greedy search with the diversity of MOGA. A flowchart of the proposed algorithm is presented in Fig. 2.

Simulation

To verify the efficacy of the proposed GSMOGA algorithm, we designed a number of simulations based on the 921 (Chi–Chi) earthquake in Taiwan, using the benchmark school29. Simulations were performed on an Intel Xeon E5620 2.4 GHz processor with 3.87 GB of RAM running on Windows XP.

Conclusion

This study proposed a novel algorithm (GSMOGA), which integrates the MOGA and the greedy algorithm with a focus on three objectives: minimizing unsatisfied demand for resources, time to delivery, and transportation costs. GSMOGA generates several feasible solutions instead of a single optimal solution as provided by existing methods. In addition, GSMOGA combines the greedy search and MOGA to overcome the disadvantages of both methods. Furthermore, GSMOGA can arrange routing schedules for each

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