Browsing by Author "Malli T."

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    Integration of fuzzy analytic hierarchy process and multi-objective fuzzy goal programming for selection problems: An application on roadheader selection
    (IOS Press BV, 2015) Ozfirat P.M.; Ozfirat M.K.; Malli T.; Kahraman B.
    In this study a general methodology employing fuzzy analytic hierarchy process and fuzzy goal programming is developed for selection problems. The proposed methodology has two main sub-phases. In the first phase, fuzzy triangular numbers are used in order to represent the comparisons among decision criteria. Then lower and upper bounds as well as mid-values of priorities belonging to each decision criteria are computed. In the second phase these values and fuzzy triangular numbers are entered into the goal programming model and the model is solved to give the final priorities of decision criteria. Then the weighted sum of ratings for each selection alternative are found where the weights are final priorities from goal programming model. The proposed methodology is presented on a real life roadheader selection problem from mining industry. The results revealed that the methodology is easily applicable and provides satisfactory results. © 2015 - IOS Press and the authors. All rights reserved.
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    The performance prediction of roadheaders with response surface analysis for underground metal mine
    (University of Kuwait, 2017) Özfirat K.M.; Malli T.; Özfirat P.M.; Kahraman B.
    Roadheaders are being used in development roads in underground mines. Especially, as total reserve is enough for large investments and mine roads, roadheaders are important to increase production rate. Roadheaders are classified according to the weight head drive or total power. In this study, the effects of several factors on roadheader performance is examined. The factors examined are power of the machine, weight of the machine, ratio of power to weight, drilling rate index, uniaxial compressive strength and rock mass rating. Instantaneous cutting ratio is used to define the performance of the machine. Response surface methodology and linear regression are used to investigate the relations between these variables. In the results of the study, machine performance is found to be highly correlated with machine power (P), weight (W) and the P/W ratio of the machine.
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    Selection of coal transportation mode from the open pit mine to the thermic power plant using fuzzy analytic hierarchy process
    (Vilnius Gediminas Technical University, 2018) Özfirat P.M.; Özfirat M.K.; Malli T.
    Coal produced in open pit mines should be moved to thermic power plants for production of power. Thermic power plants require very large amounts of coal. In transportation process of this coal, both costs and technical parameters should be considered. Common alternative transportation modes in this process are belt conveyors, truck types, suspension rail conveying systems, pipelines and railways. Selection of one of these modes is influenced by transportation distance, inclination of the haulage road, amount of coal reserve, investment costs, production capacity and unit production cost of the open pit mine. In this study, advantages and disadvantages of alternative transportation modes are analysed using Fuzzy Analytic Hierarchy Process (F-AHP). The results revealed, belt conveyors and trucks transportation by are superior to others. © 2016 Vilnius Gediminas Technical University (VGTU) Press.
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    Truck selection with the fuzzy-wsm method in transportation systems of open pit mines
    (Strojarski Facultet, 2021) Malli T.; Mizrak Ozfirat P.; Yetkin M.E.; Ozfirat M.K.
    Open pit mines gain width and become more complicated as they are deeper today, and it is inevitable to carry the produced material with a truck transportation system. Therefore, in large-scale businesses, truck selection has great importance for the transportation costs to be sustainable. This study investigates the main factors and corresponding criteria influential in selection of trucks, which are the most frequent used means of transportation in open pit mines. Analytic hierarchy process and fuzzy weighted sum model are employed to solve the selection problem. Six different truck types and 20 selection criteria are considered. As a result of technical analysis, most suitable trucks are found. © 2021, Strojarski Facultet. All rights reserved.