Infeasible solution example.

Infeasible solution example.

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This paper presents a hybrid grasshopper optimization algorithm using a novel decoder and local search to solve instances of the open vehicle routing problem with capacity and distance constraints. The algorithm’s decoder first defines the number of vehicles to be used and then it partitions the clients, assigning them to the available routes. The...

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... is relevant to notice that this decodification/codification method can lead to infeasible solutions. In Figure 3, an example of an infeasible solution is presented. The violation is made over the capacity and maximum distance constraints since for s-route Whenever a solution is infeasible after decoding, it enters the feasibility recovery procedure. ...

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Abstract Nowadays organizations outsource transportation of goods or services to reduce cost which leads to a particular type of problem called open location-routing. Also, each logistic organization possesses a limited number of specifc vehicles that may not be enough in cer�tain circumstances. This issue indicates the importance of simultaneously considering both open and closed routs. On the other hand, the growing concerns about the detrimental envi�ronmental impacts of human activities reveal the necessity of paying attention to environ�mental issues in logistics. In this study, a bi-objective mathematical programming model is proposed for two-echelon close and open location-routing problem (2E-COLRP) including two echelons of factories, depots and customers to minimize costs and CO2 emissions. The proposed model fnds the optimal routs, optimal number of vehicles and facilities as well as the locations of facilities. The augmented epsilon constraint method is used as an exact method to solve the small-sized problems. Due to complexity of model, two metaheuristic algorithms named MOGWO and NSGA-II are utilized to tackle the problems. The ef�ciency of two aforementioned algorithms is evaluated in terms of several indices consid�ering 22 problem instances with various sizes. The results show that MOGWO performs better than NSGA-II. Keywords Open location routing · Closed location routing · Environmental impact · Metaheuristic · MOGWO · NSGA-II
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Nowadays organizations outsource transportation of goods or services to reduce cost which leads to a particular type of problem called open location-routing. Also, each logistic organization possesses a limited number of specifc vehicles that may not be enough in cer- tain circumstances. This issue indicates the importance of simultaneously considering both open and closed routs. On the other hand, the growing concerns about the detrimental envi- ronmental impacts of human activities reveal the necessity of paying attention to environ- mental issues in logistics. In this study, a bi-objective mathematical programming model is proposed for two-echelon close and open location-routing problem (2E-COLRP) including two echelons of factories, depots and customers to minimize costs and CO2 emissions. The proposed model fnds the optimal routs, optimal number of vehicles and facilities as well as the locations of facilities. The augmented epsilon constraint method is used as an exact method to solve the small-sized problems. Due to complexity of model, two metaheuristic algorithms named MOGWO and NSGA-II are utilized to tackle the problems. The ef- ciency of two aforementioned algorithms is evaluated in terms of several indices consid- ering 22 problem instances with various sizes. The results show that MOGWO performs better than NSGA-II.