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Block, Jan
Publications (10 of 16) Show all publications
Ahmadi, A., Soleimanmeigouni, I., Letot, C. & Block, J. (2017). Inspection Optimization under imperfect maintenance performance. In: Diego Galar, Dammika Seneviratne (Ed.), Proceedings of MPMM 2016: 6th International Conference on Maintenance Performance Measurement and Management, 28 November 2016, Luleå, Sweden. Paper presented at Maintenance Performance and Measurement and Management 2016(MPMM 2016). November 28, Luleå, Sweden (pp. 139-). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Inspection Optimization under imperfect maintenance performance
2017 (English)In: 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, p. 139-Conference paper, Oral presentation with published abstract (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.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-63893 (URN)978-91-7583-841-0 (ISBN)
Conference
Maintenance Performance and Measurement and Management 2016(MPMM 2016). November 28, Luleå, Sweden
Available from: 2017-06-12 Created: 2017-06-12 Last updated: 2018-06-28Bibliographically approved
Block, J. (2017). Part-out Based Spares Provisioning and Management: A Study for Aircraft Retirement. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Part-out Based Spares Provisioning and Management: A Study for Aircraft Retirement
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The operation and maintenance phase of a complex technical system may deal with strategicdecisions for asset retirement and end-of-life management. When a fleet of aircraft reachesthe retirement phase, the operation of remaining fleet should still be kept at a defined level ofavailability. Obviously, the provisioning of spares is a key issue to support the maintenanceand operation of the remaining fleet. The best practice within the aviation industry is to re-usethe spares of retired aircraft to support the operational fleet. This is referred to parting-out.The purpose of the research conducted for this thesis has been to develop decision supportmethodologies, models and tools for the management of a sustainable part-out-based sparesprovisioning for an aircraft fleet during its retirement period. The proposed methodology willbe used to support the retirement process of aircraft fleet and enhance the organisation’scapability of making efficient and cost-effective decisions concerning the re-use of spare partsduring the retirement period. To achieve the purpose of this research, literature studies, casestudies, algorithm development and simulations have been conducted. Empirical data havebeen collected through document studies, interviews, and the perusal of archival records fromSaab Support and Services AB. The data analysis performed for this research has been basedon theories and methodologies within reliability analysis, cost modelling, spares forecasting,stock provisioning and decision making, in combination with the best practices implementedby the aviation industry for the end-of-life management and retirement of aircraft.In the present thesis, part-out-based spares provisioning (PBSP) program is proposed to utiliseretired aircraft units effectively as spare parts. The proposed approach is illustrated andverified through a case study performed on the “Saab-105” military aircraft fleet withinSwedish air force fleet. A PBSP programme is proposed, associated management activitiesare described, the key decision criteria are presented, and a functional framework for aneffective PBSP is suggested. The proposed PBSP program provides a foundation for furthermeasures and tasks to be performed within the retirement period, such as terminatingmaintenance contracts, discarding internal maintenance capabilities, reviewing stocks, scalingdown administrative processes (e.g. spares procurement and obsolescence monitoring), etc.An important part of the PBSP programme is the reliability analysis of multiple repairableunits, and this has been investigated, using parametric and non-parametric reliabilityapproaches. The aim is to identify a practical approach for estimation of the future sparedemand at fleet level. Furthermore, a set of computational models and search algorithm havebeen developed for the identification of applicable termination times, of both the parting-outprocess and the maintenance and repair actions performed on the units. This includestermination of the parting-out process (PO), the sending of parted-out units directly to storage(POS), and repair actions performed on the units received at the repair shops owing tocorrective (CM) and preventive (PM) maintenance, as well as the parted-out units that need tobe repaired (POM). The feasible termination alternatives are compared with regard to theirrespective costs and the most cost-effective solutions are identified.The results of the research study show that a PBSP programme can yield large reductions inmaintenance and spares procurement costs, while supporting operation of existing fleet athighest required availability. It also contributes positively to implement a green supply chainduring the retirement phase. The methodology and approaches introduced within the thesiscan be applied in other civil applications, such as energy, mining, process industry andtransportation sectors.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2017
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Aircraft retirement, End-of-life management, Parting-out, Part-out-based spares provisioning, Reliability analysis, Repairable units, Spare parts provisioning
National Category
Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-66224 (URN)978-91-7583-990-5 (ISBN)978-91-7583-991-2 (ISBN)
Public defence
2017-11-21, F1031, Luleå tekninska universitet, Luleå, 09:30
Opponent
Supervisors
Available from: 2017-10-24 Created: 2017-10-23 Last updated: 2017-11-24Bibliographically approved
Wijk, O., Andersson, P., Block, J. & Righard, T. (2017). Phase-out maintenance optimization for an aircraft fleet. International Journal of Production Economics, 188, 105-115
Open this publication in new window or tab >>Phase-out maintenance optimization for an aircraft fleet
2017 (English)In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 188, p. 105-115Article in journal (Refereed) Published
Abstract [en]

This paper presents a novel approach for cost-effective optimization of stop-maintenance strategies for a set of repairable items (rotables). The optimization method has two steps. First, the novel concept of matrix simulations is introduced to locate the solution space of the optimization problem in question. Second, a genetic algorithm is applied to find the minimum cost solution. The combination of matrix simulations and genetic algorithm is shown to constitute a powerful method for solving the optimization problem in a fast manner. To demonstrate the efficacy of the proposed method, it is compared with a crude search, and a steepest descent algorithm. Our proposed method is faster than the crude search and also locates the optimum more often than the steepest descent search. The method is illustrated by applying it to a phase-out scenario of an aircraft fleet, where the optimal stop-maintenance strategy is determined for a set of rotables.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-61342 (URN)10.1016/j.ijpe.2017.01.002 (DOI)000401381300010 ()2-s2.0-85016421015 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-04-03 (rokbeg)

Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2018-09-13Bibliographically approved
Garmabaki, A., Ahmadi, A., Block, J., Pham, H. & Kumar, U. (2016). A Reliability Decision Framework for Multiple Repairable Units (ed.). Paper presented at . Reliability Engineering & System Safety, 150, 78-88
Open this publication in new window or tab >>A Reliability Decision Framework for Multiple Repairable Units
Show others...
2016 (English)In: Reliability Engineering & System Safety, ISSN 0951-8320, E-ISSN 1879-0836, Vol. 150, p. 78-88Article in journal (Refereed) Published
Abstract [en]

In practice, the analyst is often dealing with multiple repairable units, installed in different positions or functioning under different operating conditions, and maintained by different disciplines. This paper presents a decision framework to identify an appropriate reliability model for massive multiple repairable units. It splits non-homogeneous failure data into homogeneous groups and classifies them based on their failure trends using statistical tests. The framework discusses different scenarios for analysing multiple repairable units, according to trend, intensity, and dependency of the units’ failure data. The proposed framework has been verified in a fleet of aircraft and in two simulated data sets. The results show a reliability model of multiple repairable units may contain a mixture of different stochastic models. Considering single reliability models for such populations may cause erroneous calculation of the time to failure of a particular unit, which can, in turn, lead to faulty conclusions and decisions. When dealing with massive and non-homogeneous multiple repairable units, the application of the proposed framework can facilitate the selection of an appropriate reliability model.

National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-16337 (URN)10.1016/j.ress.2016.01.020 (DOI)000373553800008 ()2-s2.0-84957998942 (Scopus ID)ff71273c-c01e-473a-8fbf-892f4c195fe4 (Local ID)ff71273c-c01e-473a-8fbf-892f4c195fe4 (Archive number)ff71273c-c01e-473a-8fbf-892f4c195fe4 (OAI)
Note
Validerad; 2016; Nivå 2; 20160204 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ahmadi, A., Soleimanmeigouni, I., Block, J. & Letot, C. (2016). Optimum failure management strategy for periodically inspected units with imperfect maintenance (ed.). Paper presented at IFAC Conference on Manufacturing Modelling, Management and Control : 28/06/2016 - 30/06/2016. IFAC PAPERSONLINE, 49(12), 799-804
Open this publication in new window or tab >>Optimum failure management strategy for periodically inspected units with imperfect maintenance
2016 (English)In: IFAC PAPERSONLINE, ISSN 2405-8963, Vol. 49, no 12, p. 799-804Article in journal (Refereed) Published
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.

Keywords
Information technology - Automatic control, Informationsteknik - Reglerteknik
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-27318 (URN)10.1016/j.ifacol.2016.07.872 (DOI)000383468400137 ()2-s2.0-84992315757 (Scopus ID)0bb5d436-fb92-4d34-a246-eb24ae77d620 (Local ID)0bb5d436-fb92-4d34-a246-eb24ae77d620 (Archive number)0bb5d436-fb92-4d34-a246-eb24ae77d620 (OAI)
Conference
IFAC Conference on Manufacturing Modelling, Management and Control : 28/06/2016 - 30/06/2016
Note

Validerad; 2016; Nivå 1; 2016-10-26 (andbra); Konferensartikel i tidskrift

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Garmabaki, A. S., Ahmadi, A. & Block, J. (2015). Fleet-level reliability estimation of repairable units (ed.). In: (Ed.), Tomasz Nowakowski; Marek Mlynczak; Anna Jodejko-Pietruczuk; Sylwia Werbinska-Wojciechowska (Ed.), Safety and Reliability: Methodology and Applications. Paper presented at European Safety and Reliability Conference : 14/09/2014 - 18/09/2014 (pp. 1977-1982). London: CRC Press
Open this publication in new window or tab >>Fleet-level reliability estimation of repairable units
2015 (English)In: Safety and Reliability: Methodology and Applications / [ed] Tomasz Nowakowski; Marek Mlynczak; Anna Jodejko-Pietruczuk; Sylwia Werbinska-Wojciechowska, London: CRC Press, 2015, p. 1977-1982Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates reliability analysis of a repairable unit at fleet level. In fleet, multiple similar systems are running in different operating environments. In fact, due to the highly censored data as well as high variations in failure rate within the fleet, merging the datasets becomes a challenge. The non-parametric analysis is used to capture the failure trend of repairable units at fleet level. Consequently, fleet data have been aggregated and the actual number of failure has been compared with the expected total number of failures. In addition, parametric models are used to model the reliability trend obtained through a non-parametric approach to identify the reliability parameters at fleet level. Real data are used to demonstrate the applicability and validity of the proposed method. Results shows the accuracy of log-linear process is reasonably acceptable.

Place, publisher, year, edition, pages
London: CRC Press, 2015
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-29930 (URN)38f0bd0a-efe6-483c-9ee3-7838244c16f5 (Local ID)9781138026810 (ISBN)38f0bd0a-efe6-483c-9ee3-7838244c16f5 (Archive number)38f0bd0a-efe6-483c-9ee3-7838244c16f5 (OAI)
Conference
European Safety and Reliability Conference : 14/09/2014 - 18/09/2014
Note
Validerad; 2016; Nivå 1; 20140805 (amigar)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-07Bibliographically approved
Block, J., Ahmadi, A., Tyrberg, T. & Kumar, U. (2014). Fleet-level Reliability of Multiple Repairable Units: a Parametric Approach using the Power Law Process (ed.). Paper presented at . International Journal of Pedagogy, Innovation and New Technologies, 10(3), 239-250
Open this publication in new window or tab >>Fleet-level Reliability of Multiple Repairable Units: a Parametric Approach using the Power Law Process
2014 (English)In: International Journal of Pedagogy, Innovation and New Technologies, ISSN 0973-1318, E-ISSN 2392-0092, Vol. 10, no 3, p. 239-250Article in journal (Refereed) Published
Abstract [en]

The application of parametric reliability analysis methods for repairable units, such as Power law process, is quite clear and straightforward for a single repairable unit. However, in practice, the analyst needs to know the reliability characteristics of units at a fleet level. The application of parametric reliability analysis methods at the fleet level, even if it is limited in scope, is quite complex. The aim of this paper is to describe the use of the power law process for multiple repairable units with differing reliability characteristics, to predict the expected number of failures at fleet level. The empirical data used in the paper are based on field data gathered during the operational life of two types of multi repairable units used in the Swedish military aircraft system FPL 37 Viggen from 1977 to 2006. The paper performs the trend test using TTT-based MIL-HDBK-189 and Laplace tests, and assesses the equality of shape-parameters for the intensity function of the power law process for multiple units. Estimation of the scale- and shape-parameters using maximum likelihood estimation is also performed. The parametric approach using power law process was found to yield relatively accurate estimations of number of failures, compared to empirical data

National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-5236 (URN)347bf29f-5ff6-45b2-b316-767cd1a4a291 (Local ID)347bf29f-5ff6-45b2-b316-767cd1a4a291 (Archive number)347bf29f-5ff6-45b2-b316-767cd1a4a291 (OAI)
Note
Validerad; 2014; 20130817 (aliahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Block, J., Ahmadi, A., Tyrberg, T. & Söderholm, P. (2014). Part-out-based spares provisioning management: A military aviation maintenance case study (ed.). Paper presented at . Journal of Quality in Maintenance Engineering, 20(1), 76-95
Open this publication in new window or tab >>Part-out-based spares provisioning management: A military aviation maintenance case study
2014 (English)In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 20, no 1, p. 76-95Article in journal (Refereed) Published
Abstract [en]

Purpose – The purpose of this paper is to present the prerequisites for a part-out-based spares provisioning (PBSP) programme during the phase-out of an aircraft fleet. Furthermore, associated key decision criteria are identified and a framework for the phase-out management process is presented. Design/methodology/approach – Once a decision has been taken to phase-out an aircraft fleet, a number of routines for operations, maintenance and storage are affected and new tasks and functions must be introduced before initiating the actual parting-out process. A decision-making system and a management framework is needed to manage spares planning during the end-of-life phase to ensure availability at minimum cost and to ensure a manageable risk of backorders. Findings – For PBSP programme during the phase-out of an aircraft fleet to succeed and be cost-effective, a number of linked processes, tasks and decisions are required, e.g., those included in the framework proposed in this paper (see Figure 3). A successful implementation of PBSP also requires that these processes and tasks are carried out in a timely manner and that the communications between the concerned parties are prompt, clear and direct. One experience from the studied case is that close and trustful contacts and cooperation between the operator and maintenance provider(s) will greatly facilitate the process. Originality/value – Although the PBSP method is fairly commonly applied within both the military and the civilian sector, somewhat surprisingly very literature has been published on the subject. Indeed, remarkably little has been published on any aspects of maintenance during the end-of-life period.

National Category
Other Civil Engineering Reliability and Maintenance
Research subject
Operation and Maintenance; Quality Technology and Management
Identifiers
urn:nbn:se:ltu:diva-12742 (URN)10.1108/JQME-09-2013-0060 (DOI)2-s2.0-84897861378 (Scopus ID)be7c5ee3-7353-4b25-ba9c-95468f7bcfd8 (Local ID)be7c5ee3-7353-4b25-ba9c-95468f7bcfd8 (Archive number)be7c5ee3-7353-4b25-ba9c-95468f7bcfd8 (OAI)
Note
Validerad; 2014; 20140415 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ahmadi, A., Block, J. & Garmabaki, A. (2014). Project: Efficient Performance Based Air Vehicle Maintenance, Supported by VINNOVA (NFFP-6), Luleå University of Technology, Saab Support and Services, SAAB Aeronautics. Paper presented at .
Open this publication in new window or tab >>Project: Efficient Performance Based Air Vehicle Maintenance, Supported by VINNOVA (NFFP-6), Luleå University of Technology, Saab Support and Services, SAAB Aeronautics
2014 (English)Other (Other (popular science, discussion, etc.))
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-35994 (URN)147cc16a-d04d-4732-bb60-c0c825205b0f (Local ID)147cc16a-d04d-4732-bb60-c0c825205b0f (Archive number)147cc16a-d04d-4732-bb60-c0c825205b0f (OAI)
Note

Status: Ongoing; Period: 01/03/2013 → 01/03/2016

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-07Bibliographically approved
Ahmadi, A., Block, J. & Garmabaki, A. (2014). Project: Enhanced Life Cycle Assessment for Performance-Based Logistics, Supported by Vinnova (NFFP-5), Saab Support Service and Luleå University of Technology. Paper presented at .
Open this publication in new window or tab >>Project: Enhanced Life Cycle Assessment for Performance-Based Logistics, Supported by Vinnova (NFFP-5), Saab Support Service and Luleå University of Technology
2014 (English)Other (Other (popular science, discussion, etc.))
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-36146 (URN)8619c382-e1f4-4a03-98c2-97626b135fb7 (Local ID)8619c382-e1f4-4a03-98c2-97626b135fb7 (Archive number)8619c382-e1f4-4a03-98c2-97626b135fb7 (OAI)
Note

Status: Avslutat; Period: 01/05/2009 → 01/05/2013

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-07Bibliographically approved
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