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EN
Recently, air pollution has received much attention as a result of reflections on environmental issues. Accordingly, the hub location problem (HLP) seeks to find the optimal location of hub facilities and allocate points for them to meet the demands between source-destination pairs. Thus, in this study, decisions related to location and allocation in a hub network are reviewed and a multi-objective model is proposed for locating and allocating capacity-building facilities at different time periods over a planning horizon. The objective functions of the model presented in this study are to minimize costs, reduce air pollution by diminishing fuel consumption, and maximize job opportunities. In order to solve the given model, the General Algebraic Modeling System (GAMS) along with innovative algorithms are utilized. The results presented a multi-objective sustainable model for full-covering HLP, and provided access to a hub network with minimum transport costs, fuel consumption, and GHG (greenhouse gas) emissions, and maximum job opportunities in each planning horizon utilizing MOICA (multi-objective imperialist competitive algorithm) and GAMS to solve the proposed model. The study also assessed the performance of the proposed algorithms with the aid of the QM, MID, SM, and NSP indicators, acquired from comparing the proposed meta-heuristic algorithm based on some indicators, proving the benefit and efficiency of MOICA in all cases.
EN
Surface and groundwater resources are two important sources in meeting agricultural, urban, and industrial needs. Random supply of surface water resources has prevented these resources from being a reliable source of water supply at all times. Therefore, groundwater acts as insurance in case of water shortage, and maintaining the quality of these resources is very important. On the other hand, studying vulnerability and identifying areas prone to aquifer pollution seems necessary for the development and optimal management of these valuable resources. Identifying the vulnerabilities of the aquifer areas to pollution will lead to a greater focus on preserving those areas. Therefore, groundwater quality assessment was performed in this study using the groundwater quality index (GQI), and groundwater vulnerability to pollution was assessed using the DRASTIC index. GQI is developed based on the values of six quality parameters (Na+, Mg2+, Ca2+, SO42-, Cl-, and TDS). The DRASTIC index is developed based on the values of seven parameters (depth to the water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, hydraulic conductivity). The zoning of both indexes has been done using geographic information system (GIS) software. The results show that the GQI of the region was about 93, and its DRASTIC index was about 86. Therefore, the quality of aquifer groundwater is excellent, and its vulnerability to pollution is low.
EN
Nowadays, some manufacturing organizations may well face production restrictions. For example, in case the number of products goes up, the company might not be capable of producing all products. As a consequence, the company may face backlogging. In the meanwhile, in case the demand for products rises, the given company may experience a restricted capacity to react to that kind of demand properly; thus, it will suffer backlogging. Over the course of this study, that kind of company facing the mentioned circumstances is considered. To meet those exceeded demands, companies would be forced to purchase some products from outside. Thus, the study's primary aim is to define and calculate the optimum make and buy a number of products so that overall inventory cost is reduced and optimized. To do so, a model is proposed referred to as the make-with-buy model. This model is designed and solved by exact solution software in the based branch and bound method. The results of the study confirm the feasibility and efficiency of this method and demonstrate that this model can be applied to lessen the overall inventory costs, including maintenance, order, setup, and purchasing costs, and also the total costs of products.
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