Saeed Alinezhad; Seyyed-Mahdi Hosseini-Motalgh
Abstract
Most studies on decision making issue have supposed the problem in deterministic environment, and because uncertainty makes the decisions taken suboptimal, so in this paper we propose a credibility based fuzzy model for the Vehicle Routing Problem with Simultaneous Delivery and Pickup and Time Windows ...
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Most studies on decision making issue have supposed the problem in deterministic environment, and because uncertainty makes the decisions taken suboptimal, so in this paper we propose a credibility based fuzzy model for the Vehicle Routing Problem with Simultaneous Delivery and Pickup and Time Windows (VRPSDPTW). The dispatching cost of vehicles and customers’ time windows are supposed to be trapezoidal fuzzy numbers. We also proposed a hybrid meta-heuristic algorithm called Improved Particle Swarm Optimization (IPSO) for solving the problem. The proposed algorithm is the combination of Particle Swarm Optimization (PSO) and some removal and insertion techniques which helps to improve the searching ability and maintain diversity of solutions. Finally, to demonstrate the applicability of the proposed model in the real world we studied the distribution of dairy products among customers by a distribution company in Fars province. The computational results show that distributors can use this method to reduce operating costs of the company.
Saeed Yaghobi; Mehdi Kamvar
Abstract
There are issues such as limitation of blood resources, perishability, special preservation conditions of blood products and high wastage and shortage costs of blood products, make management of blood products consumption as one of the most complex issues in healthcare systems. This paper proposes a ...
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There are issues such as limitation of blood resources, perishability, special preservation conditions of blood products and high wastage and shortage costs of blood products, make management of blood products consumption as one of the most complex issues in healthcare systems. This paper proposes a linear mathematical model to optimize consumption of the blood products in hospitals. In the proposed model, in addition to distribution of blood products between hospitals by blood center, possibility of lateral transshipments between hospitals considered as a strategy to deal with demand uncertainty. Furthermore, factor of blood freshness and the need of some surgeries for fresh blood considered in this model as real conditions. Finally, to validate the proposed model, a case related to one blood center and eight hospitals in Tehran city presented and its results discussed
