Browsing by Author "Ozfirat, MK"

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    Risk Management for Surface Plants in Mines using Risk Matrix and BowTie Analysis
    Ozfirat, MK; Ozfirat, PM; Yetkin, ME
    Surface plants in mines are important parts of a mine operation. There exist offices, common areas, repair and maintenance shops, compressed air facilities, hydraulic facilities, areas where mine machinery and parts are stacked, transportation cranes and mine stock areas in surface plants. Therefore, while the mining operations are continuing, it is necessary to control all the work in the surface plants in terms of work safety and health. In this study, the risk matrix method is used to identify and prioritize the risks of surface plants in a mine. Then, the highest priority risk, which is found to be Stock area and work environment, is considered using bowtie analysis. Four threats are determined for Stock area and work environment risk. These are improper ore or coal stock area, insufficient lighting in night works, lack of maintenance of field crane and dusty work environment. These threats are also modelled using bowtie analysis. As a result of this study, these threats, corresponding barriers and consequences can be managed by safety and operational engineers.
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    Truck Selection with the Fuzzy-WSM Method in Transportation Systems of Open Pit Mines
    Malli, T; Ozfirat, PM; Yetkin, ME; Ozfirat, MK
    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.
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    Integration of fuzzy analytic hierarchy process and multi-objective fuzzy goal programming for selection problems: An application on roadheader selection
    Ozfirat, PM; Ozfirat, MK; 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.
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    A FUZZY APPROACH TO SELECTING ROOF SUPPORTS IN LONGWALL MINING
    Yetkin, ME; Simsir, F; Ozfirat, MK; Ozfirat, PM; Yenice, H
    As a decision-making problem, selecting proper machines and equipment plays a key role for mining sites and companies. Many factors affect this decision, and values belonging to these factors can be expressed numerically and/or non-numerically. In order to make the most appropriate decision, engineers must carry out an evaluation process that comprises all criteria that might affect decision-making. To achieve this, multi-criteria decision-making tools are used. As a result of technological developments, coal outputs in longwall mining have risen tremendously over the last decades, and longwall mechanisation has become unavoidable. The significance of powered roof supports in particular increases day-by-day, since the rate of roof support has to be in accordance with the rate of face advance in longwalls. In this study, an integrated fuzzy analytic hierarchy process and fuzzy goal programming model is used to select the most suitable powered roof supports. The procedure is applied to a real-life underground coal mine that is operated using the longwall method. Seven alternative powered roof supports are compared with each other, taking a total of 24 decision criteria under four main topics into account. In conclusion, the most suitable roof supports for the mine under study are determined and recommended to the decision-makers of the system.