Ali Mohtashami; Amir Hossein Niknamfar
Abstract
Hazardous materials which are materials due to their chemical and physical properties impose significant risk to the safety of people and the environment. It's more complex routing transport of such material than normal materials. The Combination of the two subjects as the problem of locating and routing, ...
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Hazardous materials which are materials due to their chemical and physical properties impose significant risk to the safety of people and the environment. It's more complex routing transport of such material than normal materials. The Combination of the two subjects as the problem of locating and routing, it has created unified system to locating- routing problems. These problems determined optimal number and location of facilities at the same time and also set the optimal number of vehicles and their routes. The purpose of this study was design a network for the transportation of hazardous materials and includes supply levels, distribution (hub) and customers. Hence, it presented a mathematical model in order to minimizing costs and risk simultaneously. Hazardous materials sent from supplier to the hubs and deliveries to customers from there via routing by road transportation. It should be mentioned that in proposal model the hubs been locating In order to validate the model, prepared code GAMS In software and for the exact solution, sample problems with various dimensions were produced in the form of smart and random. For this purpose, was written an algorithm design in Matlab software. According to the problem was NP-Hard, presented a hybrid algorithm based on simulated annealing and genetic algorithms to solve large-scale. At the end of research the proposed algorithm were compared with the results of exact solution.
Mohammad bagher fakhrzad,; Zohre Noormogamadzade
Volume 13, Issue 38 , October 2015, , Pages 163-182
Abstract
This paper considers production scheduling and delivery problem together and is trying to integrate both of them. Retailers order includes different types of products that have been processed at a distribution center. After completing the order process at the distribution center, products are delivered ...
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This paper considers production scheduling and delivery problem together and is trying to integrate both of them. Retailers order includes different types of products that have been processed at a distribution center. After completing the order process at the distribution center, products are delivered to the retailer in window time; otherwise the distribution center is required to pay the penalty cost of window time to the retailer. The aim of solving this problem is to determine the production sequence, retailer need to heterogeneous vehicles and the visiting sequence of retailers with respect to the delivery window time. In this paper, a mixed integer linear programming model is provided in which the total cost, including the cost of vehicle routing, fixed costs and penalty costs have been minimized.in order to solve the proposed mathematical model , two approaches of CPLEX solver of GAMS software and Relaxation Lagrangian algorithm have been used. At first, by using different samples, the efficiency of Lagrangian Relaxation algorithm had been confirmed in small sizes, and then it is used in order to obtain an acceptable optimal solution in large sizes in a reasonable period.
