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  • 1.
    Aalipour, Mojgan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Human Factors Approach for Maintenance Improvement2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The purpose of this research work is to explore and describe human factors affectingmaintenance execution. To achieve the purpose of this study, the influencing factors have been identified using a literature survey. They have been categorized into four main groups namely organizational, workplace, job and individual factors. The Analytical Hierarchy Process (AHP) method is employed on data questionnaires to rank the priority of the factors. The interrelationships between these factors have been recognized by theInterpretive Structural Modelling (ISM) model. In the present case studies, MICMAC1analysis technique is also implemented for identifying the driving, dependent, linkage and autonomous factors. The data was collected through a questionnaire survey involving the participation of 16 and 25 maintenance staff and 10 mining experts in Swedish and Iranian mines, respectively. Within the study, it has been identified that the temperature, work layout, tools design and tools availability are the most important factors in both mines related to these categories. However, the significant factors in the organizational and individual categories are different in the selected mines. The effect of workplace factors on the maintainability of mining equipment is discussed and thereafter a methodology for maintainability management in the design and operation phases is developed. In the thirdcase study HEART2 is applied to estimate the probability of human error occurring duringmaintenance execution in an Iranian cable company. This research supports maintenance management to gain knowledge of human factors that affect maintenance execution. Further, this understanding could be useful in the development of strategies to improve the execution of maintenance.Keywords: Human Factors, Maintenance Management, Human Reliability, HumanPerformance, AHP, ISM, MICMAC, HEART

  • 2.
    Aalipour, Mojgan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ayele, Yonas Zewdu
    Department of Engineering and Safety, UiT The Arctic University of Norway, Tromsø.
    Barabadi, Abbas
    Tromsø University, Department of Engineering and Safety, UiT The Arctic University of Norway, Tromsø.
    Human reliability assessment (HRA) in maintenance of production process: a case study2016In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 7, no 2, 229-238 p.Article in journal (Refereed)
    Abstract [en]

    Human reliability makes a considerable contribution to the maintenance performance, safety, and cost-efficiency of any production process. To improve human reliability, the causes of human errors should be identified and the probability of human errors should be quantified. Analysis of human error is very case-specific; the context of the field should be taken into account. The aim of this study is to identify the causes of human errors and improve human reliability in maintenance activities in the cable manufacturing industry. The central thrust of this paper is to employ the three most common HRA techniques—human error assessment and reduction technique, standardized plant analysis risk-human reliability, and Bayesian network—for estimating human error probabilities and then to check the consistency of the results obtained. The case study results demonstrated that the main causes of human error during maintenance activities are time pressure, lack of experience, and poor procedure. Moreover, the probabilities of human error, obtained by employing the three techniques, are similar and consistent

  • 3.
    Aalipour, Mojgan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Barabadi, Abbas
    Tromsø University, University of Tromsø - The Arctic University of Norway.
    Maintainability management of production facilities in complex and challenging operating conditions2015In: 2015 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM): Singapore, 6-9 Dec. 2015, Piscataway, NJ: IEEE Communications Society, 2015, 817-820 p., 7385761Conference paper (Refereed)
    Abstract [en]

    As equipment becomes more complex, repair process becomes more complicated, costly and time-consuming. Maintainability principles are developed to facilitate the repair process. Maintainability principles are applied in design phase and they are characteristic that affects time, accuracy, ease and safety requirements of the repair process. Considering Maintainability principles in the design phase are critical in challenging operational conditions such as Arctic offshore. To have an effective design for maintainability a systematic management approach is required during the design phase. This paper is developed a systematic guideline for maintainability management as an engineering discipline for challenges operational condition

  • 4.
    Aalipour, Mojgan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Barabadi, Abbas
    Tromsø University, University of Tromsø - The Arctic University of Norway.
    Work place factors effect on maintainability in challenging operating conditions2015In: 2015 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM): Singapore, 6-9 Dec. 2015, Piscataway, NJ: IEEE Communications Society, 2015, 767-771 p., 7385751Conference paper (Refereed)
    Abstract [en]

    Some industries such as mining industry create complex and challenging work place for maintenance crews. For example in an underground mine, for some machines, heavy maintenance tasks must be performed on site in a limited workspace in a harsh environment, including dust and improper illumination. Such operating conditions can increase the health, safety, and environment (HSE) risk, reduce the availability of the machines and increase the life cycle cost of equipment. A review of current mining equipment design and maintenance procedure confirms that considerable reduction in HSE risk, as well as substantial cost savings, can be achieved by considering human factors. This study discusses the effect of workplace factors on the maintainability of mining equipment. It presents the results from questionnaires on the effect of work place factors on maintainability performance given to maintenance staff at two mines, one in northern Sweden and the other in Iran.

  • 5.
    Aalipour, Mojgan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Singh, Sarbjeet
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Identification of Factors affecting Human performance in Mining Maintenance tasks2014In: Proceedings of the 3rd international workshop and congress on eMaintenance: June 17-18 Luleå, Sweden : eMaintenance, Trends in technologies & methodologies, challenges, possibilites and applications / [ed] Uday Kumar; Ramin Karim; Aditya Parida; Philip Tretten, Luleå: Luleå tekniska universitet, 2014, 71-76 p.Conference paper (Refereed)
    Abstract [en]

    This paper investigates the factors affecting humanperformance in maintenance task in mining sector. Theobjective is identify various factors and to classify them asdriving (strong driving power and weak dependence) anddependent factors (weak driving power and strongdependence). The factors were identified through literaturesurvey and are ranked using mean score of data questionnaire.The reliability of measures is pretested by applyingCronbach’s alpha coefficient to responses to a questionnairegiven to maintenance personnel. The interrelationshipsbetween human factors have been recognized by interpretivestructural modeling (ISM). Further, these factors have beenclassified using matrice d'impacts croises-multiplicationappliqué à un classement (MICMAC) analysing. This casestudy will figure out the factors affecting human performancefor deriving maintenance management insights to improveproductivity in the mining sector. Further, this understandingmay be helpful in framing the policies and strategies formining industry. Temperature, lighting, documentation,communication and fitness are driving factors. Moreover,Work layout, tools availability, complex tasks, time pressure,safety, boss decisions, training, fatigue and motivation havestrong driving power as well as high dependencies and itcomes under the category of linkage factors.

  • 6.
    Abeysekera, John
    et al.
    ndustrial Ergonomics, Work Science Academy (WSA), Linköping.
    Illankoon, Prasanna
    Work Science Academy (WSA), Kandana, Sri Lanka.
    The demands and benefits of ergonomics in Sri Lankan apparel industry2016In: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 55, no 2, 255-261 p.Article in journal (Refereed)
    Abstract [en]

    Apparel exports bring in sizeable foreign income to Sri Lanka. To protect and promote this industry is a paramount need. This can be carried out by applying Human Factors/Ergonomics (HFE) which has proved to control negative effects at work places. This paper reports a case study which describes the demands and benefits of HFE in MAS Holdings which owns a large share of the apparel industry in Sri Lanka.The study consisted of walk through observation survey, a questionnaire survey and ergonomic work place analysis followed by a training programme to selected employees in three companies.Positive responses to questionnaires revealed good ergonomic practices in the work places surveyed. Ergonomically unfit chairs and potential hazards e.g. exposure to noise and hot environment were detected. It is seen that MAS have introduced strategies originated by Toyota Production System viz. 5S, Kaizen, six sigma etc., which are in fact ergonomic methods. A progressive project MAS boast of viz. ‘MAS Operating System’ (MOS) empowers training and development to employees.MAS Holdings has adequately realized the benefits of applying HFE as evident by the number of awards received. Relevant companies were advised to take appropriate corrective measures to control the potential hazards.

  • 7.
    Abrahamsson, Lena
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Johansson, Jan
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Rask, Kjell
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Fältholm, Ylva
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Bergquist, Bjarne
    Projekt: LUPO - globala länkar2010Other (Other (popular science, discussion, etc.))
  • 8.
    Ahlbäck, Ida
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Detaljplanering: Förslag till exploatering  Del av Sävast 17:42017Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
  • 9.
    Ahmadi, Alireza
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Aircraft scheduled maintenance programme development: decision support methodologies and tools2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The air transport business is large in its operations, integrated, automated and complex. Air carriers are constantly striving to achieve high standards of safety and simultaneously to attain an increased level of availability performance at minimal cost. This needs to be supported through an effective maintenance programme which has a major impact on the availability performance and which ultimately can enhance the aircraft’s capability to meet market demands at the lowest possible cost. The development of a maintenance programme is challenging, but can be enhanced by supporting methodologies and tools. The purpose of this study is to develop decision support methodologies and tools for aircraft scheduled maintenance programme development within the framework of Maintenance Review Board (MRB) process. To achieve the purpose of the research, literature studies, case studies, and simulations have been conducted. Empirical data have been collected through document studies, interviews, questionnaires, and observations from the aviation industry. For data analysis, theories and methodologies within risk, dependability and decision making have been combined with the best practices from the aviation industry. One result of the research is the identification of potential areas for improving the use of MSG-3 methodology in aircraft scheduled maintenance development. Another result is the development of a systematic methodology guided by the application of an Event Tree Analysis (ETA) for the identification and quantification of different operational risks caused by aircraft system failures, to support decision making for maintenance task development. A third result is a proposed methodology, based on a combination of different Multi-Criteria Decision Making (MCDM) methodologies, for selecting the most effective maintenance strategy for aircraft scheduled maintenance development. Finally, the fourth result is a proposed Cost Rate Function (CRF) model supported by a graphical approach. The approach can be used to identify the optimum maintenance interval and frequencies of Failure Finding Inspection (FFI) and to develop a combination of FFI and restoration tasks for the aircraft’s repairable items which are experiencing aging. These results are related to some of the specific industrial challenges, and are expected to enhance the capability of making effective and efficient decisions during the development of maintenance tasks. The results have been verified through interaction with experienced practitioners within major aviation manufacturers and air operators.

  • 10.
    Ahmadi, Alireza
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An assessment of operational consequences of failures to support aircraft scheduled maintenance program development2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    A majority of the direct and indirect maintenance costs in the life cycle of aircraft stems from the consequences of decisions taken during the initial maintenance program development. In particular, the preventive and corrective maintenance requirements, which greatly influence both the system availability and life cycle cost, need to be defined in order to perform only those preventive actions that are absolutely necessary and costeffective. Reliability-Centered Maintenance (RCM) is a systematic methodology used to identify the preventive maintenance tasks that are necessary to realize the inherent reliability of equipment at the lowest possible cost. Developing a scheduled maintenance program by means of RCM consists of identifying those preventive tasks which are both applicable (technically feasible) and effective (worth doing). An applicable maintenance task must satisfy the requirements of the type of failure to restore the item's initial performance capability. To be effective, a preventive maintenance task must lead to a reduced risk (or expected loss) of the consequence classes to a level which is acceptable to the user. In the design development phase, in order to identify the most cost effective solution, a design trade-off study is needed. This involves choosing the correct balance of the cost of consequences of failure and its correction, with their cost of prevention. However, during initial aircraft maintenance program development, lack of a methodology that supports the assessment of the operational consequences of failures has made the costeffectiveness analysis of maintenance tasks a challenging issue. This might reduce the accuracy of the analysis, which results in higher maintenance costs and may decreases the punctuality of operation, which ultimately increases the total aircraft life cycle cost. The purpose of this study is to develop a methodology for identifying different operational consequences and associated costs caused by aircraft system failure, in order to facilitate and enhance the capability of taking correct and efficient decisions when analyzing the cost-effectiveness of maintenance tasks. Some empirical studies of possible scenarios involving aircraft failures and their operational consequences for a commercial airline have been performed. Empirical data were extracted through document studies and interviews, guided by the application of an Event Tree Analysis (ETA). The analysis was performed together with experienced practitioners from both an aircraft manufacturer and commercial airlines, which contributed to a continuous verification of the outcomes of the study. Finally, the study has also estimated the associated cost of the identified operational consequences of failures. In order to quantify the operational consequences of failures, in the absence of adequate and reliable data, a methodology using pair-wise comparison technique has been applied to extract judgments of experts efficiently

  • 11.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Arasteh Khouy, Iman
    Kumar, Uday
    Schunnesson, Håkan
    Selection of maintenance strategy, using analytical hierarchy process2009In: Communications in Dependability and Quality Management, ISSN 1450-7196, Vol. 12, no 1, 121-132 p.Article in journal (Refereed)
    Abstract [en]

    Selection of appropriate maintenance strategy is key to economic viability of aviation and manufacturing industries. The study discusses and presents an approach to facilitate the selection of the most appropriate maintenance strategy on the basis of the cost-benefit analysis by using Analytical Hierarchical Process (AHP). The goal is to select the most cost-effective alternative, among Run-To-Failure (RTF), Preventive Maintenance (PM), incorporating Prognostic Health Management(PHM) capability, or any possible Design-Out Maintenance (DOM) strategies, which positively affects on aircraft operational availability. In this paper we proposed a stepwise algorithm to guide the selection process, based on two criteria of operational availability (benefit) and cost of failure.

  • 12.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Block, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Project: Efficient Performance Based Air Vehicle Maintenance, Supported by VINNOVA (NFFP-6), Luleå University of Technology, Saab Support and Services, SAAB Aeronautics2014Other (Other (popular science, discussion, etc.))
  • 13.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Block, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Project: Enhanced Life Cycle Assessment for Performance-Based Logistics, Supported by Vinnova (NFFP-5), Saab Support Service and Luleå University of Technology2014Other (Other (popular science, discussion, etc.))
  • 14.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Block, Jan
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Risk based maintenance deferral for components subject to hidden failure2012In: 2012 proceedings: Annual Reliability and Maintainability Symposium (RAMS 2012) : Reno, Nevada 23-26 Jan. 2012, Piscataway, NJ: IEEE Communications Society, 2012Conference paper (Refereed)
    Abstract [en]

    In the aviation industry, it may be necessary to employ a combination of Failure Finding Inspection (FFI) and a scheduled discard task at a specific threshold, when a component is aging and its failures are hidden and exert a “safety effect”. This is to ensure an adequate level of availability of hidden functions, and to reduce the risk of multiple failures to an acceptable level. However, in some situations, operators prefer to extend the discard life of components beyond their recommended life limit, due to operational needs or logistic issues. This necessitates the definition of an optimal Failure Finding Inspection interval for the extended life period. The main purpose of this paper is to develop analytical and graphical methodologies to identify the optimal FFI interval for extension of the discard life of aircraft components. The paper considers repairable components which are periodically tested. The methodology assumes that the inspection and repair actions lead to as-bad-as-old (ABAO) reliability characteristics.The graphical approach proposed in this paper considers inspection and repair times, as well as the costs associated with accidents, inspection, and repair, and it takes into account the opportunity losses due to the maintenance downtime. The analytical approach for calculating the unavailability of the hidden function is based on the Mean Fractional Dead Time (MFDT).

  • 15.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Franson, Torbjörn
    Saab Aerosystems, Linköping.
    Crona, Anneli
    Saab Aerosystems, Linköping.
    Klein, Markus
    Saab Aerosystems, Linköping.
    Söderholm, Peter
    Integration of RCM and PHM for the next generation of aircraft2009In: 2009 IEEE Aerospace Conference: Big Sky, Montana, USA, 7 - 14 March 2009, Piscataway, NJ: IEEE Communications Society, 2009Conference paper (Refereed)
    Abstract [en]

    With global cuts in defense budgets, air forces have to sustain the same level of readiness with a reduced number of aircraft. To succeed with this challenge, it is not sufficient to improve current maintenance concepts, but new ones also have to be introduced.Traditionally, the development of on-board functions and maintenance concepts has been performed rather independently. The new approach is to focus on an integration of these two developments and to adapt a life cycle view together with a disregard of organizational boundaries.To facilitate the necessary change, a study is performed by Saab and Luleå University of Technology. The study focuses on the possibilities to integrate RCM and PHM in a cost-effective way. The aim is to reduce the workload of maintenance development and to find out how to combine RCM and PHM to achieve a joint development of the aircraft and its maintenance program throughout the aircraft's whole life cycle.The paper describes some similarities and differences between RCM and PHM. Furthermore, the paper describes some aspects of how RCM and PHM are complementing each other and what kind of adaptations that has to be done to achieve a successful integration. For example, a good application of RCM early in system design might generate a pull for PHM-technology integration and motivate design changes of the aircraft. Simultaneously, available PHM-technologies might strongly affect the selection of applicable and effective maintenance tasks in the development of the initial maintenance program. PHM might also support a surveillance of the maintenance program's performance. The description is highlighted with examples and experiences from the Swedish Gripen fighter aircraft. Finally, the paper also outlines some suggestions for further research.

  • 16.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Optimum inspection interval for hidden functions during extended life2015In: International Journal of COMADEM, ISSN 1363-7681, Vol. 18, no 3, 45-49 p.Article in journal (Refereed)
  • 17.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir Soleimani
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Optimum inspection interval for hidden functions during extended life2014Conference paper (Refereed)
  • 18.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Optimum Failure Finding Inspection During Extended Operation Life2013Conference paper (Refereed)
    Abstract [en]

    In a complex system such as railway and aviation equipment’s, it may be necessary to employ a combination of Failure Finding Inspection (FFI) and a scheduled discard task, as suggested by Reliability-Centered Maintenance (RCM). This strategy ensures an adequate level of availability of hidden functions, as well as the reduction of the risk of multiple failures to an acceptable level. However, in some situations, operators prefer to extend the discard life of components beyond their recommended life limit, due to the operational restrictions. This necessitates the definition of an optimal Failure Finding Inspection interval for the extended life period. This paper aims to provide a mathematical model for defining optimal FFI interval, during the extended period of the replacement life. A cost function (CF) is developed to identify the cost per unit of time associated with different FFI intervals, for the proposed extended period of life, i.e. postponement period. The proposed method concerns as-bad-as-old (ABAO) inspection and repairs (due to failures found by inspection). It considers inspection and repair times, and takes into account the costs associated with inspection and repair, the opportunity cost of lost production due to maintenance downtime created by inspection and repair actions, and also the cost of accidents due to the occurrence of multiple failure

  • 19.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Gupta, Suprakash
    Banaras Hindu University, Varanasi.
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Estimation of economic consequences of aircraft system failures2012In: Communications in Dependability and Quality Management, ISSN 1450-7196, Vol. 15, no 1, 39-49 p.Article in journal (Refereed)
    Abstract [en]

    A large portion of the direct and indirect aircraft operational costs stems from the consequences of decisions made during the maintenance program development. Decision on maintenance task selection for non-safety category of failures, is based on the cost effectiveness, in which the cost of preventive maintenance should be less than the costs associated with the corrective action and failure consequence. Although the assessment of the direct cost for preventive and corrective maintenance is quiet straightforward, however quantification and estimation of the cost associated with the consequence of failure is a great challenge. This is due to a long list of contributory factors and lack of adequate data regarding the cost headings. This study attempts to estimate the economic consequences of aircraft system failures which lead to a technical delay. The paper considers financial losses, mostly due to the additional unexpected costs related to the flight crew, passengers, aircraft itself, ramp and airport, when one of the cost headings, e.g. the pre-fixed crew cost is known. The experience of the field experts has been used following a pairwise comparison technique to compare the cost headings, and to estimate the contribution of each one to the total cost of a delay. The study shows that the proposed model can be a tool to assess the cost of failure consequences in aircraft operation, when there is a limited data and information regarding the cost headings.

  • 20. Ahmadi, Alireza
    et al.
    Gupta, Suprakash
    Banaras Hindu University, Varanasi.
    Karim, Ramin
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Selection of maintenance strategy for aircraft systems using multi-criteria decision making methodologies2010In: International Journal of Reliability, Quality and Safety Engineering (IJRQSE), ISSN 0218-5393, Vol. 17, no 3, 223-243 p.Article in journal (Refereed)
    Abstract [en]

    This paper, proposes the Multi-Criteria Decision Making (MCDM) methodology for selection of a maintenance strategy to assure the consistency and effectiveness of maintenance decisions. The methodology is based on an AHP-enhanced TOPSIS, VIKOR and benefit-cost ratio, in which the importance of the effectiveness appraisal criteria of a maintenance strategy is determined by the use of AHP. Furthermore, in the proposed methodology the different maintenance policies are ranked using the benefit-cost ratio, TOPSIS and VIKOR. The method provides a basis for consideration of different priority factors governing decisions, which may include the rate of return, total profit, or lowest investment. When the preference is the rate of return, the benefit-cost ratio is used, and for the total profit TOPSIS is applied. In cases where the decision maker has specific preferences, such as the lowest investment, VIKOR is adopted. The proposed method has been tested through a case study within the aviation context for an aircraft system. It has been found that using the methodology presented in the paper, the relative advantage and disadvantage of each maintenance strategy can be identified in consideration of different aspects, which contributes to the consistent and rationalized justification of the maintenance task selection. The study shows that application of the combined AHP, TOPSIS, and VIKOR methodologies is an applicable and effective way to implement a rigorous approach for identifying the most effective maintenance alternative.

  • 21.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Gupta, Suprakash
    Kumar, Uday
    Assessment of the cost of operational consequences of failures in aircraft operation2007In: Proceedings of 3rd International Conference on Reliability and Safety, 2007Conference paper (Refereed)
    Abstract [en]

    Maintenance decisions regarding aircraft require consideration of the operational impact of failures. The cost of the operational impact of failure is difficult to assess due to the influence of a large number of contributory factors. This study attempts to assess the cost of operational consequences of failures using the expertise of the field experts following a pairwise contribution technique. The study shows that the proposed model can be a tool to assess the cost of operational consequences of failures in aircraft operation, when there is not sufficient and reliable data

  • 22. Ahmadi, Alireza
    et al.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Barabady, Javad
    Prerequisites for a business-oriented fleet availability assurance program in aviation2010In: Proceedings of the 1st international workshop and congress on eMaintenance, Luleå: Luleå tekniska universitet, 2010, 168-175 p.Conference paper (Refereed)
    Abstract [en]

    The air transport business is a large, integrated, automated and complex domain with high requirements on safety, security and dependability. In order to achieve customer satisfaction and gain a global competitive advantage, provision of services is essential. In air transport business with an extensive competition, the consequences of unreliable services become more critical which may increase cost of operation and reduce productivity. Furthermore, occurrence of unreliable services might also lead to annoyance, inconvenience and a lasting customer dissatisfaction that can create serious problem with regarding the responsible company‟s marketplace position. Hence, it is crucial for air transport companies to continuously improve the quality of the services they provide to customer. In the context of air transport, maintenance process and maintenance-related services have a high impact on effectiveness, productivity and costs. Maintenance departments are required to ensure that their fleet is expected to meet, or continues to meet, airline‟s established availability performance goals (e.g. operational readiness, dispatch reliability and cost affectivity) and to ensure that demands for deliveries will met. One way to align maintenance decisions and business objectives and at the same time highlight where the potential weakness in the systems and maintenance performance can be expected, is through Fleet Availability Assurance Program (FAAP). However, an effective implementation of FAAP needs adaptation to the usage context. Hence, the purpose of this paper is to present an availability assurance program in airline industries, in which the essential functional elements of such a program are discussed. The paper also proposes an integrated information logistic infrastructure for this management system.

  • 23.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Cost based risk analysis to identify inspection and restoration intervals of hidden failures subject to aging2011In: IEEE Transactions on Reliability, ISSN 0018-9529, E-ISSN 1558-1721, Vol. 60, no 1, 197-209 p.Article in journal (Refereed)
    Abstract [en]

    The analytical model presented in this paper aims to study possible maintenance strategies considering risk constrains, to preserve or assure availability of hidden functions of a repairable unit in aircraft systems considering ageing effect. The paper discusses two known strategies for hidden failure management aviation and other high risk industries, namely Failure Finding Inspection (FFI), and a combination of a series of FFI and restoration after a specific number of FFI cycles ( i.e., FFI-Rs strategy). Based on discussions, the paper introduces a new approach named Dynamic Failure Finding Inspection strategy (DFFI) to assure the acceptable level of risk and also the unit's hidden function availability continuously . The paper presents analytical methods to estimate optimal FFI, and optimal thresholds for restoration of degradation (refreshing risk level) within FFI-Rs strategy. It also discusses criteria used to select appropriate thresholds to change the FFI intervals within DFFI strategy, i.e. reducing inspection intervals after specific thresholds, to reduce the risk. The method is based on the mean proportion of time i.e. (Mean Functional Dead Time, MFDT) that the unit is not functioning during the inspection intervals and the average unavailability behavior within the restoration/discard period. The proposed method considers inspection, repair, and restoration times, and takes in to account costs associated with inspection, repair, restoration, potential losses due to non-availability of aircraft due to maintenance downtime or accident often caused multiple failures.

  • 24. Ahmadi, Alireza
    et al.
    Kumar, Uday
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Risk based maintenance decision for periodically tested repairable components subject to hidden failure2011In: Proceedings of 2nd International Conference on Reliability, Safety and Hazard - ICRESH 2010: Mumbai Dec 15-16, 2010 / [ed] P V Varde, Piscataway, NJ: IEEE Communications Society, 2011, 197-204 p.Conference paper (Refereed)
    Abstract [en]

    This paper aims to develop a graphical method to facilitate the identification of risk and cost of postponement of restoration for repairable components which are periodically tested and whose failures are hidden, i.e, are detectable by inspection or upon demand. The paper focuses on the items which are under aging, however, the methodology is flexible to implement for any aging pattern. The paper considers Failure Finding Inspection (FFI) with restoration actions (FFI+Res), for the “safety effect” categories of hidden failures. As-bad-as-old (ABAO) inspection effectiveness and as-good-as-new (AGAN) restoration effectiveness are considered. In case of repair due to findings by inspection, as-bad-as-old repair effectiveness is considered. The graphical methodology proposed in this paper considers inspection and repair times, as well as the costs associated with accident, inspection, repair, and restoration, and takes into account the opportunity losses due to the maintenance downtime. The analytical approach is based on the Mean Fractional Dead Time. In the case of an operational limit, when it is not possible to remove the unit for restoration, or one needs to use the unit longer than the expected operating time, the paper introduces an approach to analyzing the possibility of and conditions for providing an extension to the restoration interval that satisfies the risk constraints and the business requirements at the same time.

  • 25.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Söderholm, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    On aircraft scheduled maintenance program development2010In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 16, no 3, 229-255 p.Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to present issues and challenges of scheduled maintenance task development within the maintenance review board (MRB) process, and to find potential areas of improvement in the application of the MSG-3 methodology for aircraft systems. Design/methodology/approach – The issues and challenges as well as potential areas of improvement have been identified through a constructive review that consists of two parts. The first part is a benchmarking between the Maintenance Steering Group (MSG-3) methodology and other established and documented versions of reliability-centred maintenance (RCM). This benchmarking focuses on the MSG-3 methodology and compares it with some RCM standards to identify differences and thereby find ways to facilitate the application of MSG-3. The second part includes a discussion about methodologies and tools that can support different steps of the MSG-3 methodology within the framework of the MRB process. Findings – The MSG-3 methodology is closely related to the RCM methodology, in which the anticipated consequences of failure are considered for risk evaluation. However, MSG-3 considers neither environmental effects of failures nor operational consequences of hidden failures. Furthermore, in MSG-3, the operational check (failure-finding inspection) is given priority before all other tasks, whereas in RCM it is considered as a default action, where there is no other applicable and effective option. While RCM allows cost-effectiveness analysis for all failures that have no safety consequences, MSG-3 just allows it for failures with economic consequences. A maintenance program that is established through the MRB process fulfils the requirements of continuous airworthiness, but there is no foundation to claim that it is the optimal or the most effective program from an operator’s point-of-view. The major challenge when striving to achieve a more effective maintenance program within the MRB process is to acquire supporting methodologies and tools for adequate risk analysis, for optimal interval assignments, and for selection of the most effective maintenance task. Originality/value – The paper presents a critical review of existing aircraft scheduled maintenance program development methodologies, and demonstrates the differences between MSG-3 and other RCM methodologies.

  • 26. Ahmadi, Alireza
    et al.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Söderholm, Peter
    Risk of operational consequences of aircraft system failure2010In: International Journal of Pedagogy, Innovation and New Technologies, ISSN 0973-1318, E-ISSN 2392-0092, Vol. 6, no 2, 149-158 p.Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to describe a methodology for identifying different operational consequences and associated costs caused by aircraft system failure, in order to facilitate and enhance the capability of taking correct and efficient decisions when analyzing the cost-effectiveness of maintenance tasks. The paper focuses on the operational consequences of failures that lead to delay. To identify the operational consequences of aircraft system failures, Empirical studies of possible scenarios involving aircraft failures and their operational consequences for a commercial airline have been performed. Empirical data were extracted through document studies and interviews, guided by the application of an Event Tree Analysis (ETA). In order to effectively utilize the knowledge of field experts in the assessment process, a pairwise comparison technique was adopted for quantifying the contribution of different factors to the operational. The work was performed together with experienced practitioners from both an aircraft manufacturer and commercial airlines, which contributed to a continuous verification of the outcome of the study.The study shows that the proposed methodology based on ETA and pairwise comparison can be used to identify and quantify the cost of operational consequences of failures in aircraft operation, when there is no sufficient and reliable data.

  • 27.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Soleimanmeigouni, Iman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Block, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Letot, Christophe
    University of Mons.
    Optimum failure management strategy for periodically inspected units with imperfect maintenance2016In: IFAC PAPERSONLINE, ISSN 2405-8963, Vol. 49, no 12, 799-804 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to develop a reliability-based cost model for periodically inspected units subject to hidden functions, with imperfect restoration (overhaul) action after a certain number of inspections. In the model, effectiveness of the consecutive restoration actions is considered, and possible alternative maintenance strategies are identified and compared. The method is based on the Total Cost and identifies the optimum interval and frequency of inspections, as well as restoration that minimize the total life cycle cost. In the proposed model, repair due to failures found by inspection is considered as minimal repair, and restoration/overhaul action is considered as normal repair. The result also shows that for a specific value of restoration effectiveness (θ0), when θ> θ0, the behavior of alternatives tends to as-bad-as-old and for θ< θ0 tends to an as-good-as-new. It is also observed that when the cost of accident is high it is needed to perform inspections at smaller intervals.

  • 28.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Soleimanmeigouni, Iman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Letot, Christopher
    Machine Design and Production Engineering Unit, Research Institute for the Science and Manage ment of Risks, University of Mons.
    Block, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Inspection Optimization under imperfect maintenance performance2017In: Proceedings of MPMM 2016: 6th International Conference on Maintenance Performance Measurement and Management, 28 November 2016, Luleå, Sweden / [ed] Diego Galar, Dammika Seneviratne, Luleå: Luleå tekniska universitet, 2017, 139- p.Conference paper (Refereed)
    Abstract [en]

    Scheduled maintenance and inspection development is one of the main requirements for emergency equipment and safety devices. These types of devices have hidden functions which are used intermittently or infrequently, so their failure will not be evident to the operating crew. The analytical model presented in this paper deals with the periodically tested units with overhauls (preventive maintenance) after certain number of inspections and a renewal after a series of overhauls. The cost based optimization method presented in this paper identifies the optimum interval and frequency of Failure Finding Inspection (FFI) and restoration. In the proposed model, repair due to failures found by inspection makes the unit As Bad As Old, and restoration/overhaul action rejuvenates the unit to any condition between As Good As New and As Bad As Old. As Good As New effectiveness also is considered for renewal action. It considers inspection and repair times, and takes into account the costs associated with inspection, repair, restoration, and also the cost of accidents due to the occurrence of multiple failure. The results show that when the unit is not under aging process, the optimal alternative for each inspection interval is the one with highest possible number of inspection without restoration. Finally, it is observed that when the cost of accident is quite high it is needed to perform inspections at smaller intervals to control the risk of accident.

  • 29. Ahmadi, Alireza
    et al.
    Söderholm, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Assessment of the operational consequences of aircraft failures: using event tree analysis2008In: 2008 IEEE Aerospace Conference: 1-8 March 2008 : [Big Sky, Montana]., Piscataway, NJ: IEEE Communications Society, 2008, 1-14 p.Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to describe a methodology that supports an assessment of the operational consequences of failures in aircraft systems and its associated costs, in order to facilitate a correct and efficient decision-making during cost-effectiveness analysis of maintenance tasks within scheduled aircraft maintenance program development. The paper is based on empirical studies of possible scenarios from aircraft failure to operational consequences in commercial airlines. Empirical data was extracted through document studies and interviews, guided by the application of an Event Tree Analysis (ETA). The analysis was performed together with experienced practitioners from both an aircraft manufacturer and commercial airlines, which contributed to a continuous verification of the outcomes of the study. The proposed methodology, which is based on ETA, is considered as a valuable support in the assessment of the operational consequences of failures within a MSG-3 framework. The proposed methodology focuses on assessing the operational consequences of failures and associated economical losses. Hence, in order to enable an estimation of the maintenance tasks' cost-effectiveness, the methodology should be further developed to include a cost assessment of the applicable maintenance tasks. The proposed methodology could be adapted as a support to those involved in the development of aircraft maintenance program. The operational consequences and the probabilities of the proposed event tree can be quantified by the aid of historical data or expert judgment.

  • 30.
    Ahmadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Söderholm, Peter
    Kumar, Uday
    An overview of trends in aircraft maintenance program development: past, present, and future2007In: Risk, Reliability and Societal Safety: Pproceedings of the European Safety and Reliability Conference 2007 (ESREL 2007), Stavanger, Norway, 25 - 27 June 2007 / [ed] Terje Aven; Jan Erik Vinnem, London: Taylor and Francis Group , 2007, 2067-2076 p.Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to describe the trends in aircraft maintenance program development during the last 50 years, including the reasons for the aircraft industry to change its view of maintenance. The major milestones and fundamental reasons for such development are also discussed and illustrated in relation to a flow diagram, which shows the logical and chronological order of the trends. Finally, the paper describes some possibilities and challenges as regards applying Information & Communication Technology (ICT) within the emerging approach of e-Maintenance in order to enhance the surveillance of aircraft maintenance program performance.

  • 31.
    Ahmadi, Mahdieh
    et al.
    Department of Industrial Engineering, Mazandaran University of Science and Technology, Babol.
    Mahdavi, Iraj
    Department of Industrial Engineering, Mazandaran University of Science and Technology, Babol.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Multi up-gradation Software Reliability for Open Source Software2016In: Current Trends in Reliability, Availability, Maintainability and Safety: An Industry Perspective / [ed] Uday Kumar; Alireza Ahmadi; Ajit Kumar Verma; Prabhakar Varde, Encyclopedia of Global Archaeology/Springer Verlag, 2016, 691-702 p.Conference paper (Refereed)
    Abstract [en]

    Nowadays, software companies have to continuously do up-gradation or add-ons in their software to survive in the market. This paper presents an effective reliability model for multi release open source software (OSS), which derived based on software lifecycle development process (SDLC) proposed by Jørgensen [1]. Most of OSS reliability models proposed in the literature are based on closed-form methodology and do not consider the properties of OSS in the model structure. The proposed model, incorporate bugs removed from two different phases, namely a pre-commit test and parallel debugging test. Furthermore, the proposed model is based on the assumptions that the overall fault removal of the new release depends on the reported faults from the previous release of the software and on the faults generated due to adding some new functionalities to the existing software system. The parameters of model have been estimated on real software failure dataset with three releases and goodness of fit of values have been calculated. Results show that the proposed model fits the data reasonably well and present better accuracy in comparison with other methods.

  • 32.
    Ahmadi, Mahdieh
    et al.
    Department of Industrial Engineering, Mazandaran University of Science and Technology, Babol.
    Seneviratne, Dammika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An approach to Symbolic Modelling: a Railway Case study for Maintenance Recovery Level Identification2017In: Proceedings of MPMM 2016: 6th International Conference on Maintenance Performance Measurement and Management, 28 November 2016, Luleå, Sweden / [ed] Diego Galar, Dammika Seneviratne, Luleå: Luleå tekniska universitet, 2017, 187- p.Conference paper (Refereed)
    Abstract [en]

    Increasing demand for quality and reliability of the asset is progressively seen as a motivation for improved maintenance procedure and management. Always the role of qualitative maintenance data is neglected in the maintenance recovery level identification. Human factor parameter in the maintenance and qualitative technical data, for instance, maintenance experience, maintenance knowledge, training, quality before maintenance, number of previous maintenance, maintenance documentation and environmental condition can be collected and evaluated to increase the accuracy of maintenance recovery estimation. This information always expressed linguistically and considering their effect in the recovery model is challenging. The aim of this study is to propose a symbolic model to capture the effect of above qualitative factor on maintenance recovery level. Fuzzy inference systems are applied to qualitative expert knowledge to extract the percentage effect which can be incorporated in the recovery level model. The tamping railway case study is considered to validate the model. The results show that the maintenance experience and environmental condition are playing main role in maintenance quality. The application of above method can be extended to asset condition assessment in combination with data driven and physical model

  • 33.
    Ahmadzadeh, Farzaneh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Mean Residual Life Estimation Considering Operating Environment2012Conference paper (Refereed)
    Abstract [en]

    The cost of maintenance of mechanized and automated mining systems is too high necessitating efforts to enhance the effectiveness of maintenance systems and organization. For effective maintenance planning, it is important to have a good understanding of the reliability and availability characteristics of the systems. This is essential for determining the Mean Residual Life (MRL) of systems so that maintenance tasks could be planned effectively. In this paper we used the statistical approach to estimate MRL. A Weibull proportional hazard model (PHM) with time-independent covariates was considered for modelling of the hazard function so that operating environment could be integrated in the reliability analysis. Methods are presented for calculating the conditional reliability function and computing the MRL as a function of the current conditions to guarantee the desired output. The model is verified and validated using data from the Hydraulic system of an LHD fleet from a Swedish mine. The results obtained from the analysis is useful to estimate the remaining useful life of such system which can be subsequently used for effective maintenance planning and help controlling unplanned stoppages of highly mechanized and automated systems.

  • 34.
    Ahmadzadeh, Farzaneh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Application of multi regressive linear model and neural network for wear prediction of grinding mill liners2013In: International Journal of Advanced Computer Sciences and Applications, ISSN 2158-107X, E-ISSN 2156-5570, Vol. 4, no 5, 53-58 p.Article in journal (Refereed)
    Abstract [en]

    The liner of an ore grinding mill is a critical component in the grinding process, necessary for both high metal recovery and shell protection. From an economic point of view, it is important to keep mill liners in operation as long as possible, minimising the downtime for maintenance or repair. Therefore, predicting their wear is crucial. This paper tests different methods of predicting wear in the context of remaining height and remaining life of the liners. The key concern is to make decisions on replacement and maintenance without stopping the mill for extra inspection as this leads to financial savings. The paper applies linear multiple regression and artificial neural networks (ANN) techniques to determine the most suitable methodology for predicting wear. The advantages of the ANN model over the traditional approach of multiple regression analysis include its high accuracy.

  • 35.
    Ahmadzadeh, Farzaneh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Remaining useful life estimation: Review2014In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 5, no 4, 461-474 p.Article in journal (Refereed)
    Abstract [en]

    This paper reviews the recent modelling developments in estimating the remaining useful life (RUL) of industrial systems. The RUL estimation models are categorized into experimental, data driven, physics based and hybrid approaches. The paper reviews some typical approaches and discusses their advantages and disadvantages. According to the literature, the selection of the best model depends on the level of accuracy and availability of data. In cases of quick estimations which are less accurate, the data driven method is preferred, while the physics based approach is applied when the accuracy of estimation is important.

  • 36.
    Ahmadzadeh, Farzaneh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Remaining useful life prediction of grinding mill liners using an artificial neural network2013In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 53, 1-8 p.Article in journal (Refereed)
    Abstract [en]

    Knowing the remaining useful life of grinding mill liners would greatly facilitate maintenance decisions. Now, a mill must be stopped periodically so that the maintenance engineer can enter, measure the liners’ wear, and make the appropriate maintenance decision. As mill stoppage leads to heavy production losses, the main aim of this study is to develop a method which predicts the remaining useful life of the liners, without needing to stop the mill. Because of the proven ability of artificial neural networks (ANNs) to recognize complex relationships between input and output variables, as well as its adaptive and parallel information-processing structure, an ANN has been designed based on the various process parameters which influence wear of the liners. The process parameters were considered as inputs while remaining height and remaining life of the liners were outputs. The results show remarkably high degree of correlation between the input and output variables. The performance of the neural network model is very consistent for data used for training (seen) and testing (unseen).

  • 37.
    Ahmadzadeh, Farzaneh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Strömberg, Thomas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Multivariate process parameter change identification by neural network2013In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 69, no 9-12, 2261-2268 p.Article in journal (Refereed)
    Abstract [en]

    Whenever there is an out-of-control signal in process parameter control charts, maintenance engineers try to diagnose the cause near the time of the signal which is not always lead to prompt identification of the source(s) of the out-of-control condition and this in some cases yields to extremely high monetary loses for manufacture owner. This paper applies multivariate exponentially weighted moving average (MEWMA) control charts and neural networks to make the signal identification more effective. The simulation of this procedure shows that this new control chart can be very effective in detecting the actual change point for all process dimension and all shift magnitudes considered. This methodology can be used in manufacturing and process industries to predict change points and expedite the search for failure causing parameters, resulting in improved quality at reduced overall cost. This research shows development of MEWMA by usage of neural network for identifying the step change point and the variable responsible for the change in the process mean vector.

  • 38.
    Aitomäki, Yvonne
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Allard, Christina
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Lin, Janet
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sandström, Anders
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    LTU Teaching guide to e-learning: how to clear the mist of teaching through the cloud2015Conference paper (Other academic)
  • 39. Akersten, Per-Anders
    Condition monitoring and risk & relability analysis2006In: Condition Monitoring and Diagnostic Engineering Management: COMADEM 2006 ; proceedings of the 19th international congress, Luleºa, Sweden, 12 - 15 June 2006 / [ed] Uday Kumar, Luleå: Luleå tekniska universitet, 2006, 555-561 p.Conference paper (Refereed)
    Abstract [en]

    Qualitative and semi-quantitative reliability and risk analyses are usually performed, using inductive analysis approaches, e.g. FMEA/FMECA (Failure Mode and Effects [Criticality] Analysis), PHA (Preliminary Hazard Analysis) or HAZOP (Hazard and Operability Study). After the identification of possible failure modes or hazards, their possible effects at different system levels are estimated. In several cases the possible effects at higher system levels are very severe, indicating that the system under study is highly unreliable or hazardous. This conclusion, however, can be modified by taking into account the effect of current controls or countermeasures that can reduce the likelihood of an adverse effect or reduce the severity. Condition monitoring provides a useful risk control approach, primarily aiming at reducing the likelihood of an adverse effect. In this paper this risk control approach is described in some more detail and a proposed methodology is described. This methodology combines FMEA and ETA (Event Tree Analysis), with special attention taken to the utilization of Condition Monitoring.

  • 40. Akersten, Per-Anders
    E-maintenance and vulnerability2006In: Engineering Asset Management: Proceedings of the First World Congress on Engineering Asset Management (WCEAM) / [ed] Joseph Mathew; Lin Ma; Andy Tan; Deryk Anderson, London: Encyclopedia of Global Archaeology/Springer Verlag, 2006, 120-124 p.Conference paper (Refereed)
    Abstract [en]

    Teleservice, utilizing modern information processing and communication tools, is by now a well-known way of supporting a product and we have seen the emergence of e-manufacturing and related types of e-service, in particular e-maintenance. In discussions of the present and future of emanufacturing and e-maintenance systems are among other things risks and vulnerabilities related to utilization of e-services identified as an important area for further research. In this paper the concepts of emaintenance and vulnerability are briefly described. The vulnerability of the e-maintenance system and its consequences for the managed assets are discussed to some extent. From different risk analysis approaches, e.g. related to computer and network security, several methodologies and tools for the management of vulnerability can be identified and an analysis methodology is proposed. The paper represents the view of a risk analyst and reliability engineer.

  • 41. Akersten, Per-Anders
    Loss control management: som maintenance aspects2000In: Euromaintenance 2000: the International 15th Maintenance Congress : 7th-10th of March, 2000 in Gothenburg, Sweden, Swedish Maintenance Society (Fören. Underhållsteknik) , 2000, 361-365 p.Conference paper (Refereed)
  • 42. Akersten, Per-Anders
    Maintenance management should be based on core values, methodologies and tools2002In: Proceedings: ICOMS-2002, International Conference of Maintenance Societies : Queensland Hilton Hotel, 21 - 24 May 2002, Brisbane, Queensland, Central Queensland University, 23 - 24 May 2002, Gladstone, Queensland, Brisbane, 2002Conference paper (Refereed)
  • 43. Akersten, Per-Anders
    Maintenance-related IEC dependability standards2006In: Engineering Asset Management: Proceedings of the First World Congress on Engineering Asset Management (WCEAM), London: Encyclopedia of Global Archaeology/Springer Verlag, 2006, 115-119 p.Conference paper (Refereed)
    Abstract [en]

    Within the International Electrotechnical Commission, IEC, there exists a committee, named IEC Technical Committee 56 "Dependability", TC56 for short. Its history can be traced back to 1965, when the Reliability and Maintainability Committee was formed. In 1990, after contacts with ISO, it was decided that the IEC/TC56 should be responsible for standardization in the field of dependability, in any appropriate technological area, including those normally considered as outside the scope of IEC. The term "dependability" is a collective term, used to describe availability performance and its constituent factors reliability performance, maintainability performance, and maintenance support performance. Within the IEC/TC56 a number of maintenance related standards and guidelines have been produced, covering e.g. maintainability of equipment, reliability-centred maintenance, integrated logistic support, and also an application guide entitled "Maintenance and maintenance support". Also, Chapter 191 of the International Electrotechnical Vocabulary, freely available on the Internet, contains a wealth of maintenance-related terms. This paper is intended to give an overview of the standards available and some insight into the ongoing efforts within IEC/TC56 to produce new standards and to maintain existing ones. It should not be seen as an official promotion of the IEC Dependability Standards series. Instead, it presents some personal experiences and reflections on the use and usefulness of the standards series.

  • 44. Akersten, Per-Anders
    Managing product support requirements: some examples2004In: Asset management: 21st century core competency ; 8th International Conference of Maintenance Societies ; Star City, Sydney, Australia, 25 - 28 May 2004 ; proceedings, Sidney: MESA - Maintenance Engineering Society of Australia , 2004Conference paper (Refereed)
  • 45. Akersten, Per-Anders
    et al.
    Espling, Ulla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Postponed Replacement: A Risk Analysis Case Study2005In: ICOMS-2005: International Conference of Maintenance Societies : maintenance planning and practice - back to basics, 31 May - 2 June, Hobart, Australia, Melbourne: MESA - Maintenance Engineering Society of Australia , 2005Conference paper (Refereed)
  • 46. Akersten, Per-Anders
    et al.
    Klefsjö, Bengt
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Dependability management as a management system based on core values, methodologies and tools2001In: Safety and reliability: towards a safer world : proceedings of the European Conference and Reliability, ESRel 2001, Torino, Italy 16 - 20 September / [ed] Enrico Zio ; Micaela Demichela; Norberto Piccinini, Torino: Politecnica , 2001, 245-252 p.Conference paper (Refereed)
  • 47. Akersten, Per-Anders
    et al.
    Klefsjö, Bengt
    Total dependability management2003In: Handbook of Reliability Engineering, London: Encyclopedia of Global Archaeology/Springer Verlag, 2003, 559-565 p.Chapter in book (Other academic)
    Abstract [en]

    The authors strongly believe that the system view of dependability management will facilitate organizations to work with dependability matters, since things are "put together to create a whole". Total dependability management builds upon the availability and use of all three management system components: a set of supporting core values, an appropriate methodology, and the skillful use of contextually adapted tools.

  • 48. Akersten, Per-Anders
    et al.
    Klefsjö, Bengt
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Bergman, Bo
    Chalmers University of Technology.
    Graphical techniques for analysis of data from repairable systems2010In: Handbook of statistics vol. 20: Advances in reliability, Amsterdam, 2010, 469-484 p.Chapter in book (Other academic)
  • 49.
    Al-Douri, Yamur K.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Information assurance for maintenance of railway track2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Railway traffic is steadily increasing, having a negative impact on maintenance and resulting in decreased track availability, comfort, and safety. Swedish railway track maintenance mostly focuses on the actual track condition via a nationwide condition-based maintenance (CBM) strategy. For maintenance to be conducted in an appropriate way, data on the actual track condition must be accurate; furthermore, those data need to be converted into accurate information for maintenance decisions. An information assurance (IA) framework has the potential to deal with the system risks from a technical perspective. The framework is a guideline that can be implemented within CBM to understand both condition monitoring data behaviour and the information processing used to reach maintenance decisions.This research investigates ways of an information assurance (IA) framework can be implemented in the following CBM steps: data collecting, data processing and making maintenance decisions on Swedish railway. The framework can be used to understand data behaviour, information processing and the communication between information layers for decisions at organisation, infrastructure and data/information levels. The research uses both qualitative and quantitative methods to investigate critical information data, parameters, and problems and to suggest which areas need improvement. Quantitative analysis of the Swedish track geometry database reveals specific information about the behaviour of the railway data and their processing to make maintenance decisions.A case study shows how certain sections of a railway track are monitored and evaluates maintenance practices on those sections. The study finds several different types of measurements are taken using several different measurement systems. It is difficult to integrate these data for proper processing. In addition, there are problems of incomplete or irregular data; this affects the derivation of information and the use of models to understand track irregularities.Given the problems of data processing and subsequent decision making, the study suggests implementing an IA framework with CBM. The study checks the achievement of three IA principles in the existing data: authenticity, integrity and availability. The results show data have problems of authenticity and integrity, something also mentioned by the stakeholders in interviews. In particular years and on certain track sections, CM data are more than 5 percent incomplete, significantly affecting analysis. Incomplete track measurement data reach as high as 63 percent for the parameters of standard deviation (STD), longitudinal level and STD cooperation. Inaccurate measured values for alignment long wavelength within certain speed limits reach as high as 71 percent. These indicators are important for calculating track quality but are either incomplete or incorrect, negatively affecting the calculation of the Q-value and estimations of the track quality. This, in turn, negatively affects the maintenance decisions. Using information assurance will increase the system performance by permitting stakeholders to make accurate decisions.The suggested information assurance framework can discover technical problems but it needs to be improved using technologies, techniques and services to ensure complete and accurate data are available to be processed for maintenance decisions.

  • 50.
    Al-Douri, Yamur K.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Al-Jumaili, Mustafa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Information security in e-maintenance: a study of Scada security2012Conference paper (Refereed)
    Abstract [en]

    eMaintenance solutions are spreading increasingly due to the continuous evolution in the different Information and Communication Technology (ICT) tools. In general, most of the available eMaintenance solutions are depending on Internet infrastructure what makes them vulnerable to all security threats that affect the Internet. One of the important eMaintenance solutions is Supervisory Control and Data Acquisition (SCADA) system as it has been used in most of the industrial processes. SCADA systems were designed without security considerations as they were mainly installed into isolated networks. Nowadays, SCADA systems are mainly connected to Internet and other networks. Therefore, SCADA systems have been exposed to wide range of network security threats. Hence, SCADA security has become an important aspect that needs to be investigated. In this paper, a study of SCADA security issues will be done. The main contribution of this paper is to address SCADA security issues and challenges related to eMaintenance.

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