taher kouchaki tajani; Ali Mohtashami; maghsoud Amiri; Reza Ehtesham Rasi
Abstract
in this paper we have proposed a model based on Mixed Integer Non-Linear Programming for the blood supply chain under conditions of uncertainty in supply and demand, from the stage of receiving blood from volunteers to the moment of distribution in demand centers. The challenges addressed in this optimization ...
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in this paper we have proposed a model based on Mixed Integer Non-Linear Programming for the blood supply chain under conditions of uncertainty in supply and demand, from the stage of receiving blood from volunteers to the moment of distribution in demand centers. The challenges addressed in this optimization model are the reduction of blood supply chain costs along with minimizing the shortage and expiration rate of blood products. The Markov chain has been used to address the uncertainty of donor blood supply. And to estimate the needs of medical centers, the received demand is considered fuzzy. Then The proposed model is solved in small dimensions by GAMS software and in large dimensions by Bat and Whale meta-heuristic algorithms and the results are presented. In addition, a case study is presented to show the applicability of the proposed model. The results show a reduction in the level of costs as well as a reduction in the shortage and expiration of blood products in the supply chain.
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.
Ali Mohtashami; Sarvenaz Tayyebi
Volume 8, Issue 20 , March 2011, , Pages 101-128
Abstract
Managers in organizations. In this paper an innovative model for calculating amount of incentive payments to employee has been proposed. Considering the multi criteria nature of assessing organization’s employees, this research propose a methodology to face this problem using multiple criteria ...
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Managers in organizations. In this paper an innovative model for calculating amount of incentive payments to employee has been proposed. Considering the multi criteria nature of assessing organization’s employees, this research propose a methodology to face this problem using multiple criteria decision making technique. To evaluating the effectiveness of this model, the suggested model has been implemented for an electromotor manufacturing company and the results has been mentioned in article. Considering the high ability of TOPSIS technique in solving the large scale (large number of alternatives and criteria), this technique will be used for computations. The suggested model has been used for five production departments (163 persons) in mentioned company and amount of incentive payment for each one of employees has been calculated.
S.M. Ali Khatami Fivouzabadi; Mohsen Rahimi; Ali Mohtashami
Volume 5, Issue 14 , December 2006, , Pages 29-54
Abstract
In this paper, we will consider the problem of courses timetabling in a small educational institute. We will present the mathematical model considering six hard constraints (compelling constraints) and five soft constraints (constraints that are lot compelling, but regarding them results increasing the ...
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In this paper, we will consider the problem of courses timetabling in a small educational institute. We will present the mathematical model considering six hard constraints (compelling constraints) and five soft constraints (constraints that are lot compelling, but regarding them results increasing the utility of timetable). To formulating the model we will use a type of goal programming. In this paper we will try to define decision variables, hard constraints, soft constraints and objective function in a step by step direction. Afterward we will test the model on a mathematical example.
