| 1. |
- Allahkarami, Zeynab, et al.
(författare)
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Identifying the mixed effects of unobserved and observed risk factors on the reliability of mining hauling system
- 2021
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer. - 0975-6809 .- 0976-4348. ; 12:2, s. 281-289
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Tidskriftsartikel (refereegranskat)abstract
- Reliability is widely used as a performance indicator of mining equipment to achieve a cost-effective maintenance plan. Reliability is a function of time as well as environmental and operational factors. Applying an adequate model by taking into account the mentioned factors is vital to ensure an accurate estimation of reliability characteristics. The aim of this study is to investigate the application of mixed frailty model to describe both observed and unobserved heterogeneity in reliability analysis of mining equipment. The capability of the model is assessed using field data from a fleet of dump trucks in an open-pit mine. The results indicate that the proposed model is superior to the traditional Cox model when data are heterogeneous. The results also show that the operator's skill and road conditions have a significant effect on the reliability of dump trucks.
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| 2. |
- Allahkarami, Zeynab, et al.
(författare)
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Mixed-effects model for reliability assessment of dump trucks in heterogeneous operating environment: A case study
- 2022
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Ingår i: Quality and Reliability Engineering International. - : John Wiley & Sons. - 0748-8017 .- 1099-1638. ; 38:5, s. 2881-2898
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Tidskriftsartikel (refereegranskat)abstract
- Reliability of mining equipment is influenced by different operational and environmental risk factors. However, in practice, including all relevant factors in reliability analysis is not possible. Ignoring the risk factors leads to unobserved heterogeneity and biased estimation of reliability characteristics. This research proposes a semi-parametric mixed-effects model to assess the simultaneous effects of observed and unobserved risk factors on reliability. Furthermore, the model can be used for investigating inter-cluster dependency and variability. To illustrate the model, a comprehensive case study is presented using data from three mines in Iran. The results show that the model can address the effect of unobserved risk factors. Moreover, it is found that the hazard of dump trucks is significantly associated with operator skill, season and the elevation difference between dumping and loading points.
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| 3. |
- Allahkarami, Zeynab, et al.
(författare)
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Reliability Analysis of Motor System of Dump Truck for Maintenance Management
- 2016
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Ingår i: Current Trends in Reliability, Availability, Maintainability and Safety. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319235967 - 9783319235974 ; , s. 681-688
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Konferensbidrag (refereegranskat)abstract
- Dump truck is one of the main machinery in open pit mines. From an economic point of view, more than 50–60 % of production costs in open pit mines are allocated to hauling and loading costs, so it is important to keep equipment in good condition. Reliability is a useful tool for evaluating the performance of this machine. In this research, the reliability of motor subsystem of a dump truck in Miduk Copper Mine in Iran has been analyzed. The failure data were collected during 20 months of dump truck operation. Trend and serial correlation tests were used to validate the assumption of independent and identically distribution (IID). According to tests, the data are independent and identically distributed therefore the renewal process technique is used for modelling. For finding the best-fit distribution, different types of statistical distributions were tested using the Easyfit software. The analysis results indicated the time between failures (TBF) data obey the Weibull (3p) distribution. The developed model based on these data showed that the reliability of the motor subsystem decreases to a zero value after approximately 430 h of operation. Regarding to the obtained reliability plot, preventive reliability-based maintenance time interval for 90 % reliability levels for machine in the motor subsystem is 21 h.
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