Papers by Ali Nouri Qarahasanlou
International Journal of System Assurance Engineering and Management, 2017
The appropriate maintenance strategy for a specific system requires a detailed analysis of the sy... more The appropriate maintenance strategy for a specific system requires a detailed analysis of the system's reliability. Reliability analysis relies greatly on the historical failure and repair data. Lack of data, poor quality data, data censoring, and combining data from different systems working in different operating conditions are some of the challenges for maintenance analysts. Hence, based on the nature of historical failure and repair data (independence of data, constant failure rates, identically distributed variables, etc.), an appropriate statistical model should be selected to predict the reliability of the system. Thereafter, based on the defined reliability characteristics of the system, an appropriate maintenance strategy needs to be established. In this study, a systematic methodology is developed, based on the available guidelines for maintenance strategy selection, founded on the reliability analysis of historical failure data. The application of the methodology is shown by a case study from the crushing and mixing bed hall unit at a cement factory.
Springer eBooks, 2022
Throughput capacity (TC) is defined as the total amount of material processed or produced by the ... more Throughput capacity (TC) is defined as the total amount of material processed or produced by the system in the given time. In practice, full capacity performance for industrial equipment is impossible because the failures are affected and cause a reduction. Therefore, failure interruptions, especially critical ones (bottlenecks), must be detected and considered in production management. From the point of production view, the bottleneck has the lowest production or performance. Most of the previous works used the availability and related importance measures as performance indicators and prioritization of subsystems. However, these measures cannot consider system production in their prioritization. This paper presents a bottleneck detection framework based on system performance and production capacity integration. The integrated approach is used to assess the loading and hauling subsystems of Golgohar Iron Mine, Iran. As a result of the analysis, the hauling subsystem identifies the system's bottleneck.
PLOS ONE, Jul 15, 2020
It is an essential task to estimate the remaining useful life (RUL) of machinery in the mining se... more It is an essential task to estimate the remaining useful life (RUL) of machinery in the mining sector aimed at ensuring the production and the customer's satisfaction. In this study, a conceptual framework was used to determine the RUL under the reliability analysis in a frailty model. The proposed framework was implemented on a Komatsu PC-1250 excavator from the Sungun copper mine. Also, the Weibull-frailty model was selected to describe the failure behavior and compare it with the classical-exponential model. The frailty model was also used to evaluate the impact of unobserved environmental conditions on the RUL values. Both applied models were fitted to the obtained data from 80 operational hours of the Komatsu PC-1250 excavator. Plotting the results from the reliability analysis of two models demonstrated that the mine system with the frailty model performs better than the classical model before reaching the reliability of 80%. Besides, the frailty model shows a coherent with the operational time of the excavator, while the classical model demonstrates a sinusoid variation. The obtained results may be used for the development of maintenance, preventive repairs planning, and the spare parts replacement intervals.
Research Square (Research Square), Jun 21, 2021
Nowadays, tunnel excavation plays a major role in development of countries. Due to the complex an... more Nowadays, tunnel excavation plays a major role in development of countries. Due to the complex and challenging ground conditions, a comprehensive study and analysis must be done before, during and also after the excavation of tunnels. Hence, the importance of study and evaluation of ground settlement are dramatically increased, since many tunnel projects are performed in the urban areas where there are plenty of constructions, buildings and facilities. For this reason, the control and prediction of ground settlement is one of the complicated topic in the fields of risk engineering. Therefore, in this paper, proportional hazard model (PHM) is used to analyze and study the ground settlement induced by Tabriz Metro Line 2 (TML2) tunneling. The PHM method is a semi-parametric regression method that can enter environmental conditions or factors affecting settlement probability. These influential factors are used as risk factors in the analysis. After establishing a database for a case study and using proportional hazard model for surface settlement analysis, and then, by evaluating the effect of environmental conditions on the ground surface settlement, it has been found that the risk factors of grouting pressure behind the segment, the ratio of tunnel depth to groundwater level, and drained cohesion strength at a significant level of 5% have a direct effect on the probability of settlement. The results also showed that the effect of grout injection pressure on ground subsidence is more than other parameters, and with increasing injection pressure, the probability of exceeding safe subsidence values decreases. In addition, it has been found that increasing the risk factor for the ratio of tunnel depth to groundwater level reduces the probability of exceeding the safe ground settlement. Finally, increasing the number of risk factors for drained cohesion strength increases the probability of exceeding safe settlement.
Journal of Mining and Environment, Oct 1, 2019
The appropriate operating of mining machines is affected by both the executive and environmental ... more The appropriate operating of mining machines is affected by both the executive and environmental factors. Considering the effects and the related risks lead to a better understanding of the failures of such machines. This leads to a proper prediction of the reliability parameters of such machines. In this research work, the reliability and maintainability analysis of the loading and haulage machines in the Sungun Copper Mine, considering the repair condition as multiple repairable units, was performed. For this purpose, the data necessary for the loading and haulage equipment including 2 loaders and 8 dump trucks for a 15-month period was collected and categorized in 10 operational units after the system and subsystems of the department were determined. Initially, the time between failures (TBFs) and time to repair (TTR) for each unit was calculated. Then 20 subsystems were developed. Primarily, the Stata software was utilized to carry out the heterogeneity test for all the subsystems. In consequence, most of the subsystems were regarded as the heterogeneous ones, except for 7 of them including the dump truck units 1, 2, 3, 4, 5, 7, and 8 in TBFs. Hence, "PHM" that is a covariate-based model displayed the heterogeneous group. Its reliability function was also estimated. For the next step, the trend tests were done on the non-heterogeneous subsystems by means of the Minitab software. The homogeneous subsystems with failure trend were modeled by "NHPP". Afterwards, the non-trended subsystems formed the data group. Later, the correlation tests were modeled by "HPP". Finally, the reliability and maintainability functions were calculated with the 95% confidence level.
International Journal of Mining, Reclamation and Environment, Sep 15, 2017
Abstract Maintenance cost is a significant part of production costs. Hence, logistics and spare p... more Abstract Maintenance cost is a significant part of production costs. Hence, logistics and spare part management should be considered early in the design and operational phase. The reliability characteristic of the item can be used effectively to spare part prediction (SPP). In mining industries, the reliability characteristic can be affected significantly by the operational conditions. In this study, to have an accurate SPP, covariate-based reliability models have been used to estimate the required number of tire spare parts for a dump truck fleet. The outputs represent a significant difference in the required spare parts’ management, when considering and ignoring covariates.
Journal of Mining and Environment, Jul 1, 2021
Whether directly in the form of expenses or indirectly, the objective of maintenance in the minin... more Whether directly in the form of expenses or indirectly, the objective of maintenance in the mining industry is self-evident in time losses and loss of production. In this paper, the reliability-based maintenance is examined with a different insight than before. The system goes back to the Good As New (GAN) state or too Bad As Old (BAO) maintenance state; why so, the maintenance of the system shifts to the midrange state. On the other hand, the implementation of repairs is strongly influenced by the environmental factors that are known as the "risk factors". Therefore, an analysis requires a model that integrates two basic elements: (1) incompleteness of the maintenance effect and (2) risk factors. Thus, an extensive proportional hazard ratio model (EPHM) is used as a combination of the Proportional Hazard Model (PHM) and the Hybrid Imperfect Preventive Maintenance model (HIPM) in order to analyze these elements. In this regards, four different preventive maintenance strategies are proposed. All four strategies are time-based including constant interval or periodic (the first and second strategies) and cyclic interval (the third and fourth strategies). The proposed method is applied for a Komatsu HD785-5 dump-truck in the Songun copper mine as a case study. The PM intervals with a mean value of risk factors for the four activities to reach the 80% reliability for the first and second strategies are about 5 and 48 hours. These intervals for the third strategy are calculated as 48.36, 11.58, 10.25, and 9.035, and for the fourth strategy are 5.06, 4.078, 3.459, and 1.92.
International journal of reliability, risk and safety: theory and application, Jun 1, 2022
Spare parts provision is a complex problem and requires an accurate model to analyze all factors ... more Spare parts provision is a complex problem and requires an accurate model to analyze all factors that may affect the required number of spare parts. The number of spare parts required for an item can be effectively estimated based on its reliability. The reliability characteristics of an item are influenced by different factors such as the operational environment, maintenance policy, operator skill, etc. However, in most reliability-based spare parts provision (RSPP) studies, the effect of these influence factors has not been considered. Hence, the statistical approach selected for reliability performance analysis must be able to handle the effect of these factors. One of the important models for reliability analysis by considering risk factors is the proportional hazard model (PHM), which has received less attention in the field of spare parts provisioning. Thus, this paper aims to demonstrate the application of the available reliability models with covariates in the field of spare part predictions using a case study. The proposed approach was evaluated with data from the system of fleet loading of the Jajarm Bauxite mine in Iran. The outputs represent a significant difference in spare parts forecasting and inventory management when considering covariates.
The Mining-Geological-Petroleum Engineering Bulletin, 2022
A comprehensive systemic approach is needed to make effective decisions for global sustainability... more A comprehensive systemic approach is needed to make effective decisions for global sustainability. The system's points of view introduced sustainable development (S.D.) and sustainability in prior years. Sustainable development is expressed as a desire followed by humanity to live in a better condition considering all the limits that nature could have. Social, environmental, and economic responsibilities are the wide-ranging developmental characteristics that form sustainability. In this paper, with the help of search engines like Scopus and Web of Science, several documents related to environmental sustainability in the mining industry were studied. The principal investigated problems were tailings dam failure, forestland use in mining operations, social and environmental issues in crushed stone mining industries, landfill mining challenges, climatic problems, economic problems, and fatalities in artisanal and small-scale mines. Also, a table was designed to categorise these problems and determine the solution and primary goal. This study investigates the severity of mining operation conditions and environmental issues in this industry. The common environmental problems in the mining industry include soil degradation, deforestation, land subsidence, acid mine drainage, waste production, natural landscape destruction, coal production, carbon footprint, dust pollution, greenhouse gas emissions and climatic problems. To have a more sustainable mining industry, all the mining stages, from the exploration to the post-closure stages, must minimise resource and energy consumption and waste products.
Proceedings Of The Institution Of Mechanical Engineers, Part O: Journal Of Risk And Reliability, Dec 6, 2017
Production performance analysis plays a significant role in supporting the decision-making proces... more Production performance analysis plays a significant role in supporting the decision-making process, for managers and engineers dealing with the challenges of the optimization procedure of a system delivery capacity. Operational conditions can influence the production performance of a system drastically, in a short or long term, by affecting the system configuration, reliability, maintainability, maintenance supportability, and functional capacity of its components. Moreover, these impacts can lead to increased business risks and uncertainties. Such a situation demands the successful application of tools and methodologies to minimize the total business risk through an accurate prediction of production performance, addressing the effects of operational conditions. However, there is a lack of practical methodologies, for production performance analysis of systems operating under the time-dependent operational conditions. Hence, the central thrust of this article is to develop a systematic methodology, for the production performance analysis of a system considering the time-dependent operational conditions. In the case study, the results show that the production performance of mining equipment is affected significantly by the operational conditions. These changes occur across the working shifts and due to any changes in the production plan of the mine. The result of the analyses shows that the critical items in the mine is the loader. Hence, in order to increase the production performance of the system, the optimization of the reliability or maintainability of the loader needs to be considered as a priority. Moreover, the wagon drill has a significant excess capacity, which means that, by adding more trucks to the system, the production performance of the system can be improved.
Resources Policy, May 1, 2023
Springer eBooks, 2022
The concept of availability importance measures can be used to identifying critical components fr... more The concept of availability importance measures can be used to identifying critical components from the availability performance point of view. The availability of an item depends on the combined aspects of its reliability and maintainability performance indices. These indices are considerably affected by operational and environmental conditions such as; ambient temperature, precipitation, wind, etc. Thus, different subsystems or components' availability in various conditions changes the performance priority of the system. In this way, the paper used the availability importance measure considering the operating environment for a mining fleet consisting of one shovel and six trucks. The reliability and maintainability characteristic of machines considering all influence factors (covariates) is analysed using by Cox regression model. The availability importance measure in two scenarios demonstrated that subsystem criticality changes in various conditions and the appropriate decisions should be made on different operational conditions.
PubMed, Apr 1, 2020
Background: Large-scale events such as COVID-19 show that there are situations that can lead to h... more Background: Large-scale events such as COVID-19 show that there are situations that can lead to huge stress on health infrastructure systems (HIS). The pandemic reveals that it is very difficult to protect HIS from all kinds of possible hazards. They can be unpredictable and spread rapidly; hence, it is hard to find an effective mitigation strategy to completely protect society and its important HIS. Methods: An often raised central question is what we should do if we cannot protect HIS from these types of hazards. To answer this question, the focus should move from HIS protection to HIS resilience. Therefore, in this paper, the Critical Infrastructure Resilience Index (CIRI) is used to estimate the resilience of health infrastructure systems. Results: The results of the case study show that HIS resilience was enhanced significantly after the implementation of measures. The results indicate that among the resilience phases the learning phase of resilience is the weakest part. This requires a root cause analysis, which should be prioritized by HIS managers and stakeholders. Conclusion: This paper discusses how the resilience concept will help decision- and policy-makers to have a clear view of HIS performance before, during, and after the disaster. An easy-to-use and applicable methodology for HIS assessment and evaluation was employed. It can be concluded that resilience and its identified phases can help HIS managers to allocate available resources accordingly in the phases during and post-crisis.
International Journal of Systems Assurance Engineering and Management, May 18, 2021
Resilience is about the ability of the system to resist, adapt to, and expeditiously recover from... more Resilience is about the ability of the system to resist, adapt to, and expeditiously recover from a disruptive event. The first and maybe the crucial step of resilience management is known as resilience analysis. However, there are many obstacles in front of the analyzers to analyze the resilience of systems. One of these obstacles is precise resilience data accessibility. Conventional resilience analysis methods frequently only consider historical data (e.g., time to repair and time to failure). However, to analyze the system resilience more precisely, the effect of the risk factors, which are known as observed and unobserved covariates, should be considered in the collected resilience database. These covariates will lead to the observed and unobserved heterogeneities among the collected database. Ignoring the effect of covariate may lead to erroneous conclusion about the resilience level of the system. Since it is hard to find a homogeneous operating condition, in this study, a formulation is proposed to model the effect of these covariates on complex system resilience. Finally, it is applied to a transportation system of a surface mine.
Reliability Engineering & System Safety, Nov 1, 2021
Abstract Resilience is an emerging concept whose application has increased significantly in manag... more Abstract Resilience is an emerging concept whose application has increased significantly in managing engineering systems. In order to have an effective resilience management, first, an estimation of the system resilience should be undertaken. However, a lack of historical data and limited information are major challenges for system resilience estimation. The main reason is that most data collection systems are not designed for resilience assessment. Moreover, the available study dealing with resilience assessment have been used different indices to quantify the resilience of critical infrastructures including, robustness, recoverability, etc. These indices can be affected in a complex way by different factors such as operational conditions, protective practices, the recovery process, logistic process, etc. However, the available resilience studies are not so detailed regarding identifying and quantifying these influencing factors. Therefore, this paper aims to develop and apply a practical methodology to estimate resilience based on the combination of expert judgment and fuzzy set theory. By adopting this methodology, factors influencing resilience can be modeled effectively. Finally, the application of the proposed methodology is illustrated for the main fan system of an underground coal mine.
International journal of reliability, risk and safety: theory and application, Dec 1, 2021
In civil and mining industries, Wheel loaders are an important component and their cost capabilit... more In civil and mining industries, Wheel loaders are an important component and their cost capability at effective operation. The environmental and operational factors dramatically affect the performance of loaders. In many cases, failure data are often collected from multiple and distributed units in different operational conditions, which can introduce heterogeneity into the data. Part of such heterogeneity can be explained and isolated by the observable covariates, whose values and the way they can affect the item's reliability are known. However, some factors that may affect the item's reliability are typically unknown and lead to unobserved heterogeneity. These factors are categorized as unobserved covariates. In most reliability studies, the effect of unobserved covariates is neglected. This may lead to erroneous model selection for the time to failure of the item, as well as wrong conclusions and decisions. There is a lack of sufficient knowledge, theoretical background, and a systematic approach to model the unobserved covariate in reliability analysis. This paper aims to present a framework for reliability analysis in the presence of unobserved and observed covariates. The unobserved covariates will be analyzed using frailty models (Such as Mixed Proportional Hazard).A case will illustrate the application of the framework..
Springer eBooks, 2022
Recently, to evaluate the response of systems against disruptive events, the application of the r... more Recently, to evaluate the response of systems against disruptive events, the application of the resilience concept has been increased. Resilience depicts the system's ability to return to its normal operational status after the disruption. Various studies in the field of engineering and non-engineering systems have only considered systems' performance indicators to estimate resilience. Therefore, the impact of operating and environmental factors (risk factors) has been neglected. In this paper, the influence of the risk factors (rock type), as well as the system's performance indicators, are considered in the resilience estimation of the excavator system of Gol-E-Gohar Iron mine.
Springer eBooks, 2022
The spare parts provision is a complex process, which needs a precise model to analyze all factor... more The spare parts provision is a complex process, which needs a precise model to analyze all factors with their possible effects on the required number of spare parts. The required number of spare parts for an item can be calculated based on its reliability performance. Various factors can influence the reliability characteristics of an item, including operational environment, maintenance policy, operator skill, etc. Thus, the statistical approach of choice for reliability performance analysis should assess the effects of these factors. In this study, Reliability Regression Models (RRM) with risk factors have been used to estimate the required number of crane shovels in the Jajarm bauxite mine. For this, at the first stage, all risk factors and failure data have been collected. The required data were extracted from a database of 15 months, which were collected from different sources, such as daily reports, workshop reports, weather reports, meetings, and direct observations in the format of time to failures and risk factors. After that, the potential distribution has been nominated to model the reliability of the crane shovels bucket teeth. The Akaike information criterion and Bayesian information criterion have been used to identify the best fit distribution. The candidate distribution with the smallest AIC and BIC value is the best distribution that fits the data. After that, the required number of spare parts is calculated. The results show 18% differences between the forecasted number of required spare parts when considering and non-considering the risk factors.
International. Journal of Mining & Geo-Engineering, Dec 1, 2016
Tires are of critical spare parts in mines. There is a shortage of medium and large tires. In add... more Tires are of critical spare parts in mines. There is a shortage of medium and large tires. In addition, since the mining activities and opening new mines has increased, the demand for tires has increased significantly as well. Thus, it is very important for mining engineers to identify the tire characteristics and properly manage the spare part inventory. Spare parts management is critical from an operational perspective, especially in intensive industries assets, such as mining, as well as in organizations that own and operate costly assets. A knowledge of the tires' behavior (historical data) must be taken into account along with the operating environment conditions (covariates). This study uses Cox multiple regression model to incorporate machine operating environment information into systems reliability analysis for estimation of spare parts. It considers a proportional hazard model and a stratified Cox regression model for time independent and dependent covariates. Based on the results, the study develops a mathematical model for spare parts estimation at the component level for non-repairable parts (tires). It validates the outcomes using a case study of loader tires in the Sungun mine in Iran. There is a significant difference in the results of spare parts forecasting and inventory management when considering and dismissing the covariates.
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Papers by Ali Nouri Qarahasanlou