| 1. |
- Kumar, Rupesh, et al.
(författare)
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Ergonomic issues at a railway maintenance workshop
- 2011
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Ingår i: Proceedings of the 24th International Congress on Condition Monitoring and Diagnosis Engineering Management. - : COMADEM International. - 0954130723 ; , s. 1583-1587
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Konferensbidrag (refereegranskat)abstract
- Research on human factors related to railway operation and maintenance has, to an extent, been the neglected branch of transport ergonomics. Despite the numerous reports of ergonomics programs in a variety of industries, no examples of implementing ergonomics interventions in the railway vehicle maintenance workshop have been reported.In this study, a maintenance process at a railway workshop was studied and analyzed with special reference to working posture and maintenance repair time. The working postures of two maintenance personnel were obtained and analyzed using OWAS (Ovako Working Posture Analysis System). From the results, it was clearly indicated that poor working posture was a frequent occurrence during the maintenance activities. It can be concluded that the introduction and implementation of ergonomics principles at the railway maintenance workshop must be considered in order to reduce the poor working postures, maintenance repair time and to improve maintainability and productivity.
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| 2. |
- Kumar, Rupesh, et al.
(författare)
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Improving maintainability in extreme cold climatic conditions
- 2012
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Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 8:5, s. 563-572
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Tidskriftsartikel (refereegranskat)abstract
- The maintainability issue is critical for the successful and effective operation of any industry in the extreme cold climatic conditions as the working conditions are made very difficult by low temperature, ice, short period of daylight and lack of support facilities. The objective of this paper is to identify potential risk factors in cold conditions and to provide ergonomic guidelines to reduce risk factors and increase maintainability of industries deployed in cold climate
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| 3. |
- Kumar, Saurabh, et al.
(författare)
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An approach for risk assessment of rail defects
- 2010
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Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 17:4, s. 291-311
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Tidskriftsartikel (refereegranskat)abstract
- Rail defects appear in a greater variety and frequency due to higher axle loads and increasing traffic density in passenger and freight trains. Many of these rail defects, if left undetected, can develop into rail breaks, which may lead to train derailments. Reduction in the number of such catastrophic events requires huge investments on inspection and maintenance activities. Therefore proper maintenance planning and risk assessment is required to reduce the rail maintenance cost without compromising safety. In this paper, an approach has been developed for risk assessment of rail defects to support the decision-making process during scheduling of rail inspection and grinding frequency, based on the type of defect and its risk of occurring and developing into a rail break. The approach will help in increasing the safety of passengers and rolling stock as well as reducing the overall rail maintenance cost, as it helps in making effective decisions related to inspection frequency (i.e. resource allocation according to the need). The approach is presented with the aid of a case study from the Swedish National Rail Administration (Banverket). Both, quantitative and qualitative analysis technique has been used in this paper to assess the risk of occurrence of a rail defect and its development into a rail break.
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| 4. |
- Thaduri, Adithya, et al.
(författare)
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Comparison of reliability prediction methods using life cycle cost analysis
- 2013
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Ingår i: Proceedings on the 59th Annual Reliability and Maintainability Symopsium (RAMS 2013). - 9781467347099 - 9781467347105
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Konferensbidrag (refereegranskat)abstract
- In this paper, it was discussed on the several reliability prediction models for electronic components and comparison of these methods was also illustrated. A combined methodology for comparing the cost incurring for prediction was designed and implemented with an instrumentation amplifier and a BJT transistor. By using the physics of failure approach, the dominant stress parameters were selected on basis of research study and were subjected to both instrumentation amplifier and BJT transistor. The procedure was implemented using the methodology specified in this paper and modeled the performance parameters accordingly. From the prescribed failure criteria, mean time to failure was calculated for both the components. Similarly, using 217 plus reliability prediction book, MTTF was also calculated and compared with the prediction using physics of failure. Then, the costing implications of both the components were discussed and compared them. From the results, it was concluded that for critical components like instrumentation amplifier though the initial cost of physics of failure prediction is too high, the total cost incurred including the penalty costs were lower than that of traditional reliability prediction method. But for non-critical components like BJT transistor, the total cost of physics of failure approach was too higher than traditional approach and hence traditional approach was much efficient. Several other factors were also compared for both reliability prediction methods.
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| 5. |
- Thaduri, Adithya, et al.
(författare)
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Failure modeling of constant fraction discriminator using physics of failure approach
- 2013
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Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Due to several advancements in the technology trends in electronics, the reliability prediction by the constant failure methods and standards no longer provide accurate time to failure. The physics of failure methodology provides a detailed insight on the operation, failure point location and causes of failure for old, existing and newly developed components with consideration of failure mechanisms. Since safety is a major criteria for the nuclear industries, the failure modeling of advanced custom made critical components that exists on signal conditioning module are need to be studied with higher confidence. One of the components, constant fraction discriminator, is the critical part at which the failure phenomenon and modeling by regression is studied in this paper using physics of failure methodology.
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| 6. |
- Thaduri, Adithya, et al.
(författare)
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Reliability prediction of semiconductor devices using modified physics of failure approach
- 2013
-
Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 4:1, s. 33-47
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Tidskriftsartikel (refereegranskat)abstract
- Traditional approaches like MIL-HDBK, Telcordia, and PRISM etc. have limitation in accurately predicting the reliability due to advancement in technology, process, materials etc. As predicting the reliability is the major concern in the field of electronics, physics of failure approach gained considerable importance as it involves investigating the root-cause which further helps in reliability growth by redesigning the structure, changing the parameters at manufacturer level and modifying the items at circuit level. On the other hand, probability and statistics methods provide quantitative data with reliability indices from testing by experimentation and by simulations. In this paper, qualitative data from PoF approach and quantitative data from the statistical analysis is combined to form a modified physics of failure approach. This methodology overcomes some of the challenges faced by PoF approach as it involves detailed analysis of stress factors, data modeling and prediction. A decision support system is added to this approach to choose the best option from different failure data models, failure mechanisms, failure criteria and other factors.
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| 7. |
- Thaduri, Adithya, et al.
(författare)
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Stress factor and failure analysis of constant fraction discriminator using design of experiments
- 2013
-
Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Reliability prediction using traditional approaches were implemented at earlier stages of electronics. But due to advancements in science and technology, the above models are outdated. The alternative approach, physics of failure provides exhaustive information on basic failure phenomenon with failure mechanisms, failure modes and failure analysis becomes prominent because this method depends on factors like materials, processes, technology, etc., of the component. Constant fraction discriminators which is important component in NFMS needs to study failure characteristics and this paper provides this information on failure characteristics using physics of failure approach. Apart from that, the combined physics of failure approach with the statistical methods such as design of experiments, accelerated testing and failure distribution models to quantify time to failure of this electronic component by radiation and temperature as stress parameters. The SEM analysis of the component is carried out by decapsulating the samples and studied the impact of stress parameters on the device layout.
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| 8. |
- Thaduri, Adithya, et al.
(författare)
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Study of reliability aspects in constant fraction discriminator
- 2011
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Ingår i: 5th International Conference on Quality, Reliability and Information Technology (ICQRIT). - Kathmandu. ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- Reliability prediction using conventional constant failure models by standard books in early phases of electronics dominates wide acceptance. But after 1980s, there was wide variation in electronic technology which made above models obsolete. Physics of Failure approach provides information on basic failure phenomenon with failure mechanisms and failure modes becomes prominent as it entirely depends on materials, processes, technology etc. Constant fraction discriminators which are failing frequently in the field need to be studied and this paper provides information on failure characteristics using physics of failure approach. Apart from that, we combined statistical methods such as Design of Experiments, Accelerated testing and failure distribution models to quantify time to failure of this electronic component by radiation and temperature as stress parameters.
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| 9. |
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| 10. |
- Ahmadi, Alireza, et al.
(författare)
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Cost based risk analysis to identify inspection and restoration intervals of hidden failures subject to aging
- 2011
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Ingår i: IEEE Transactions on Reliability. - 0018-9529 .- 1558-1721. ; 60:1, s. 197-209
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 11. |
- Ahmadi, Alireza, et al.
(författare)
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On aircraft scheduled maintenance program development
- 2010
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Ingår i: Journal of Quality in Maintenance Engineering. - : Emerald. - 1355-2511 .- 1758-7832. ; 16:3, s. 229-255
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 12. |
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| 13. |
- Ahmadi, Alireza, et al.
(författare)
-
Risk based maintenance decision for periodically tested repairable components subject to hidden failure
- 2011
-
Ingår i: Proceedings of 2nd International Conference on Reliability, Safety and Hazard - ICRESH 2010. - Piscataway, NJ : IEEE Communications Society. - 9781424483440 - 9781424483433 ; , s. 197-204
-
Konferensbidrag (refereegranskat)abstract
- 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.
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| 14. |
- Ahmadi, Alireza, et al.
(författare)
-
Risk based maintenance deferral for components subject to hidden failure
- 2012
-
Ingår i: 2012 proceedings. - Piscataway, NJ : IEEE Communications Society. - 9781457718496
-
Konferensbidrag (refereegranskat)abstract
- 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).
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| 15. |
- Ahmadi, Alireza, et al.
(författare)
-
Risk of operational consequences of aircraft system failure
- 2010
-
Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 6:2, s. 149-158
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 16. |
- Ahmadi, Alireza, et al.
(författare)
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Selection of maintenance strategy for aircraft systems using multi-criteria decision making methodologies
- 2010
-
Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 17:3, s. 223-243
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 17. |
- Ahmadzadeh, Farzaneh, et al.
(författare)
-
Mean Residual Life Estimation Considering Operating Environment
- 2012
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 18. |
- Al-Douri, Yamur K., et al.
(författare)
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Model-based security system for data acquisition in e-maintenance using artificial immune system and cloud computing
- 2012
-
Ingår i: International Journal of COMADEM. - 1363-7681. ; 15:4, s. 26-37
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Tidskriftsartikel (refereegranskat)abstract
- eMaintenance solutions are extensively used by the industry today. eMaintenance is an emerging technology aimed to support the industry to achieve effectiveness and efficiency in their maintenance process through enhanced use of Information and Communication Technology (ICT) . One of the essential components is an eMaintenance solution is data acquisition. Supervisory Control and Data Acquisition (SCADA) has been used to manage data acquisition is many industrial systems. Nowadays, modern SCADA systems are available through internet and other networks via IP protocol. An increased use of internet–based solution requires appropriate management approaches to improve the safety and security aspects of a system. Hence, this paper suggests a new security model based security for SCADA systems through Cloud computing and Artificial Immune System (AIS). Furthermore, the paper provides AIS, which is based on Decision Tree (C4.5 algorithm) using clustered feature set. The features set are selected from NSL-KDD cup. It is a new version of KDD dataset. As a result, two Antibodies are generated (that could recognize Normal and Antigen). After applying the resulted antibodies on the testing data set, the outputs are Normal, Antigen, and Unknown. Finally it is treated with Unknown as Antigen. As a result, high accuracy of the suggested model reaches 96.3%.
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| 19. |
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| 20. |
- Aminu Sanda, Mohammed, et al.
(författare)
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Lean instrumentation framework for sensor pruning and optimization in condition monitoring
- 2011
-
Ingår i: The Eighth International Conference on Condition Monitoring and Machinery Failure Prevention Technologies. - Longborough, Glos : Coxmoor Publishing Co.. - 9781618390141 ; , s. 202-215
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Konferensbidrag (refereegranskat)abstract
- This paper discusses a lean instrumentation framework for guiding the introduction of the lean concept in condition monitoring in order to enhance the organizational capability (i.e. human, technical and management trichotomy) and reduce the complexity in the maintenance management systems of industrial companies. Additionally, decision-making, based on severity diagnosis and prognosis in condition monitoring, is a complex maintenance function which is based on large data-set of sensors measurements. Yet, the entirety of such decision-making is not dependent on only the sensors measurements, but also on other important indices, such as the human factors, organizational aspects and knowledge management. This is because, the ability to identify significant features from large amount of measured data is a major challenge for automated defect diagnosis, a situation that necessitate the need to identify signal transformations and features in new domains. The need for the lean instrumentation framework is justified by the desire to have a modern condition monitoring system with the capability of pruning to the optimal level the number of sensors required for efficient and effective serviceability of the maintenance process. It is concluded that there are methodologies that can be developed to enable more efficient condition monitoring systems, with benefits for many processes along the value chain.
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| 21. |
- Arasteh khouy, Iman, et al.
(författare)
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Geometrical degradation of railway turnouts : a case study from a Swedish heavy haul railroad
- 2014
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 228:6, s. 611-619
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Tidskriftsartikel (refereegranskat)abstract
- Turnouts are critical components of track systems in terms of safety, operation and maintenance. Each year, a considerable part of the maintenance budget is spent on their inspection, maintenance and renewal. Applying a cost-effective maintenance strategy helps to achieve the best performance at the lowest possible cost. In Sweden, the geometry of turnouts is inspected at predefined time intervals using the STRIX / IMV 100 track measurement car. This study uses time series for the measured longitudinal level of turnouts on the Iron Ore Line (Malmbanan) in northern Sweden. Two different approaches are applied to analyse the geometrical degradation of turnouts due to dynamic forces generated by train traffic. In the first approach, the recorded measurements are adjusted at the crossing point and then the relative geometrical degradation of turnouts is evaluated by using two defined parameters, the absolute residual area and the maximum settlement, In the second approach, various geometry parameters are defined to estimate the degradation in each measurement separately. The growth rate of the longitudinal level degradation as a function of million gross tonnes / time is evaluated. The proposed methods are based on characterisation of the individual track measurements. The results facilitate correct decision-making in the maintenance process through understanding the degradation rate and defining the optimal maintenance thresholds for the planning process. In the long run, this can lead to a cost-effective maintenance strategy with optimised inspection and maintenance intervals.
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| 22. |
- Arasteh khouy, Iman, et al.
(författare)
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Geometrical degradation of switches and crossings on a Swedish heavy haul railroad : a case study
- 2013
-
Ingår i: Proceedings of 10th International Heavy Haul Association Conference. - New Delhi, India. - 9788192651903 ; , s. 26-32
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Konferensbidrag (refereegranskat)abstract
- Switches and crossings (S&Cs) are one of the most critical components of railway track systems in terms of safety, operation and maintenance. Each year, a considerable part of the maintenance budget is spent on inspection, maintenance and renewal of S&Cs. However, applying a cost-effective maintenance strategy helps to achieve the best performance at the lowest possible cost. In Sweden, the geometry of S&Cs is inspected at pre-defined time intervals by the STRIX track measurement car. In this paper, time series for the measured longitudinal level of S&Cs on the Iron Ore Line (Malmbanan) in northern Sweden have been used. Two parameters have been defined in this study, namely the absolute residual area (ARa) and the maximum settlement (Smax), to analyse the geometrical degradation of switches and crossings due to dynamic forces generated from train traffic. The paper also evaluates the growth rate of the longitudinal level degradation as a function of million gross tonnes (MGT). The results facilitate correct decision making in the maintenance process through understanding the degradation rate and defining the optimal maintenance thresholds for the planning process. In the long run this will lead to a cost-effective maintenance strategy with optimized inspection and maintenance intervals.
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| 23. |
- Asplund, Matthias, et al.
(författare)
-
Inspection of railway turnouts using camera
- 2013
-
Konferensbidrag (refereegranskat)abstract
- The railway turnout is an essential component in a railway system, used to divert traffic along different tracks. A turnout includes a number of different parts, including the switch blade, frog, point machine, switch roller, soleplate, check rail, wing rail, drive rods, control rods and other bars. These parts must be kept in good condition, meeting functional and safety requirements. Failing to comply will result in a reduction of the network’s capacity with economic consequences. Not honouring the safety limits could result in severe accidents, including derailment, causing human casualties. By performing the right type of inspection and/or maintenance at the right time, these unwanted events can be reduced. To determine if and when a maintenance action should be performed, the condition of the turnout must be established, usually by manual inspections or with measurement vehicles. The drawback is the discrete nature of these inspection events. Failure modes with development times shorter than the inspection interval could result in a malfunction of the unit. An on-line measurement system would be able to deal with these failure events and initiate correct maintenance actions at an earlier stage. With an on-line system, remotely located turnouts could be inspected without on-site personnel. Capacity consuming failures of turnouts with a strategic location or with bottleneck characteristics could also be corrected before they affect traffic. This paper describes a feasibility study of a camera based inspection system for turnouts and discusses the effect the method could have on system reliability and capacity.
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| 24. |
- Barabady, Javad, et al.
(författare)
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A framework for improvement of production plant performance using production assurance programs
- 2010
-
Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 1:1, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- The main objective of a production assurance program (PAP) for a production plant is to ensure that the planned production capacity is achieved. The assurance programs describe the activities necessary to fulfil the objectives, how they will be carried out, by whom, and when. These activities also provide input to decisions-making regarding design, manufacturing, construction, installation, operation, and maintenance of plants. It is a challenge to manage and improve production assurance. The aim of this paper is to present and discuss a methodology for improvement of production assurance performance through PAP, organized into four steps, namely data collection and information management, modeling and data analysis, generation of improvement alternatives and evaluation and decision-making.
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| 25. |
- Barabady, Javad, et al.
(författare)
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Review and discussion of production assurance program
- 2010
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Ingår i: International Journal of Quality & Reliability Management. - : Emerald. - 0265-671X .- 1758-6682. ; 27:6, s. 702-720
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to review, discuss and further develop the production assurance (PA) concept; and to define and describe a typical production assurance program (PAP) and its elements. Design/methodology/approach - An explorative literature study covering PA and dependability concept was carried out on contemporary literature. During the course of the study, meetings and discussions with a number of experts in Sweden and Norway were performed. Different types of data and examples from the oil and gas industries are used to illustrate and support the discussions. Findings - This paper indicates that the concept of PA helps the decision maker to estimate whether a production plant is able to meet customer requirements, as it provides information about the production plant's delivery capacity, production rate and ability to deliver according to design or customer demands. PAP can provide a basis for effective production control. Research limitations/implications - The material analysed was mainly related to the oil and gas industry. However, the findings and discussion can be transferred to other areas of application, such as mine production plants and chemical process plants. Practical implications - A PAP is a valuable tool for production plant managers and engineers, not only for documenting a production plant's performance, but also for providing decision support for the development and optimization of the production plant to improve the plant's performance and reduce risk and uncertainties. Originality/value - In this paper the concept of dependability is extended to include capacity performance and customer requirements or market demand, which provides a measure for delivery assurance or plant production performance in relation to customer requirements. This paper also develops a generic PAP to achieve a high level of delivery assurance.
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| 26. |
- Björling, Sten-Erik, et al.
(författare)
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Maintenance knowledge management with fusion of CMMS and CM
- 2013
-
Ingår i: DMIN 2013 International Conference on Data Mining.
-
Konferensbidrag (refereegranskat)abstract
- Maintenance can be considered as an information, knowledge processing and management system. The management of knowledge resources in maintenance is a relatively new issue compared to Computerized Maintenance Management Systems (CMMS) and Condition Monitoring (CM) approaches and systems. Information Communication technologies (ICT) systems including CMMS, CM and enterprise administrative systems amongst others are effective in supplying data and in some cases information. In order to be effective the availability of high-quality knowledge, skills and expertise are needed for effective analysis and decision-making based on the supplied information and data. Information and data are not by themselves enough, knowledge, experience and skills are the key factors when maximizing the usability of the collected data and information. Thus, effective knowledge management (KM) is growing in importance, especially in advanced processes and management of advanced and expensive assets. Therefore efforts to successfully integrate maintenance knowledge management processes with accurate information from CMMSs and CM systems will be vital due to the increasing complexities of the overall systems.Low maintenance effectiveness costs money and resources since normal and stable production cannot be upheld and maintained over time, lowered maintenance effectiveness can have a substantial impact on the organizations ability to obtain stable flows of income and control costs in the overall process. Ineffective maintenance is often dependent on faulty decisions, mistakes due to lack of experience and lack of functional systems for effective information exchange [10]. Thus, access to knowledge, experience and skills resources in combination with functional collaboration structures can be regarded as vital components for a high maintenance effectiveness solution.Maintenance effectiveness depends in part on the quality, timeliness, accuracy and completeness of information related to machine degradation state, based on which decisions are made. Maintenance effectiveness, to a large extent, also depends on the quality of the knowledge of the managers and maintenance operators and the effectiveness of the internal & external collaborative environments. With emergence of intelligent sensors to measure and monitor the health state of the component and gradual implementation of ICT) in organizations, the conceptualization and implementation of E-Maintenance is turning into a reality. Unfortunately, even though knowledge management aspects are important in maintenance, the integration of KM aspects has still to find its place in E-Maintenance and in the overall information flows of larger-scale maintenance solutions. Nowadays, two main systems are implemented in most maintenance departments: Firstly, Computer Maintenance Management Systems (CMMS), the core of traditional maintenance record-keeping practices that often facilitate the usage of textual descriptions of faults and actions performed on an asset. Secondly, condition monitoring systems (CMS). Recently developed (CMS) are capable of directly monitoring asset components parameters; however, attempts to link observed CMMS events to CM sensor measurements have been limited in their approach and scalability. In this article we present one approach for addressing this challenge. We argue that understanding the requirements and constraints in conjunction - from maintenance, knowledge management and ICT perspectives - is necessary. We identify the issues that need be addressed for achieving successful integration of such disparate data types and processes (also integrating knowledge management into the “data types” and processes).
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| 27. |
- Block, Jan, et al.
(författare)
-
Fleet-Level Reliability Analysis of Repairable Units: A Non-Parametric Approach using the Mean Cumulative Function
- 2013
-
Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 9:3, s. 333-344
-
Tidskriftsartikel (refereegranskat)abstract
- Complex technical systems are normally repaired rather than replaced when they fail. It is often desirable to analyze the reliability characteristics of these systems based on data generated in a customer use environment, in order to assess the reliability, frequency of failure or other parameters which may be influenced by the systems’ age and usage. Despite the advantages of continuously analyzing reliability data to be able to improve the maintenance programme continuously, methods such as parametric and non-parametric analysis are often ignored due to a belief that the mean time between failures (MTBF) is sufficient to describe the reliability pattern of repairable units. This paper describes the use of the mean cumulative function (MCF) and linear estimates based on the recurrence rate to predict the expected number of failures in the future. Reliability data from two repairable units are used to verify the procedure and comparison. The empirical data used in the paper is based on field data gathered during the operational life of the Swedish military aircraft system FPL 37 Viggen from 1977 to 2006, which essentially is the whole life cycle of the system.
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| 28. |
- Block, Jan, et al.
(författare)
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Fleet-level Reliability of Multiple Repairable Units: a Parametric Approach using the Power Law Process
- 2014
-
Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 10:3, s. 239-250
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 29. |
- Candell, Olov, et al.
(författare)
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Server-oriented information logistics as support to intelligent transport services
- 2010
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Ingår i: 16th World Congress and Exhibition on Intelligent Transport Systems 2009. - : Curran Associates, Inc.. - 9781617385896
-
Konferensbidrag (refereegranskat)abstract
- Today‟s society is dependent on an increasing volume of transportation services, which contributes to escalating requirements on economy, dependability, safety, and sustainability of applied transportation systems. When dealing with complex transportation systems with long life cycles, maintenance is fundamental to ensure these critical requirements. The increasing requirements and the technological development have also lead to the emerging approach of eMaintenance, which applies innovative Information & Communication Technology (ICT) to achieve effective information logistics for maintenance purposes. This paper describes the role and development of service-oriented eMaintenance solutions to enable intelligent transportation services and some related research efforts within railway and aviation.
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| 30. |
- Eker, Omer Faruk, et al.
(författare)
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Failure diagnostics on railway turnout systems using support vector machines
- 2010
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Ingår i: Proceedings of the 1st international workshop and congress on eMaintenance. - : Luleå tekniska universitet. - 9789174391206 ; , s. 248-251
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Konferensbidrag (refereegranskat)abstract
- Railway turnout systems are one of the most critical pieces of equipment in railway infrastructure. Early identification of failures in turnout systems is important to obtain increased availability and safety, and reduced operating & support cost. This paper aims to develop a method to identify „drive-rod out-ofadjustment‟ failure mode, one of the most frequently observed failure modes. Support Vector Machine with Gaussian kernel is used for classification. In addition, results of feature selection with statistical t-test and feature reduction with principal component analysis are compared in the paper.
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| 31. |
- Eker, O.F., et al.
(författare)
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SVM based diagnostics on railway turnouts
- 2012
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Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 8:3, s. 289-298
-
Tidskriftsartikel (refereegranskat)abstract
- Railway turnout systems are one of the most critical pieces of equipment in railway infrastructure. Early identification of failures in turnout systems is important to obtain increased availability and safety, and reduced operating and support costs. This paper aims to develop a method to identify 'drive-rod out-of-adjustment' failure mode, one of the most frequently observed failure modes. Support Vector Machine (SVM) with Gaussian kernel is used for diagnosis. In addition, the results of feature selection with statistical t-test and feature reduction with principal component analysis (PCA) are compared in the paper
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| 32. |
- Famurewa, Stephen Mayowa, et al.
(författare)
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Comparative study of track geometry quality prediction models
- 2013
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Ingår i: 10th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2013, CM 2013 and MFPT 2013. - 9781629939926 ; , s. 1057-1068
-
Konferensbidrag (refereegranskat)abstract
- Track geometry quality is an important aspect in railway engineering as it reflects the actual condition of a track giving account of track geometry deviations. Monitoring and prediction of a relevant geometry quality parameter over time provides opportunity for effective maintenance with advantage of extending the life of the asset, reducing maintenance cost and minimizing possession time requirements. Two important aspects of good maintenance practice relating to track geometry quality are quality assessment of every measurement run for special and common cause of variations and also understanding the progression of the deterioration process. This gives engineering insight into temporal failure phenomena including the behaviour of track structure over time that can facilitate condition forecasting and consequent maintenance planning. This paper presents an approach for assessing track geometry data and also compares three track quality prediction models- linear, exponential and suggested GM(1,1) models. A series of inspection data from a selected line section of Trafikverket (Swedish transport administration) is used in the study. The contribution of this paper is the improvement of prediction accuracy of track geometry model, which is an essential consideration in failure prediction technique.
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| 33. |
- Famurewa, Stephen Mayowa, et al.
(författare)
-
Composite indicator for railway infrastructure management
- 2013
-
Konferensbidrag (refereegranskat)abstract
- The assessment of efficiency and effectiveness of past maintenance decisions and actions is an essential element in maintenance process. The significance of this is not only limited to communicating the value contribution of maintenance to overall business objectives but also to drive maintenance for improvement and towards excellence. However the existence of numerous maintenance result areas and many operational level indicators often lead to distributed information that is not in a suitable format required to support decision making. This paper motivates the use of fuzzy logic approach to aggregate selected indicators to appreciate the information bit distributed in each indicator. The selected indicators include measures related to safety, comfort, punctuality, availability and reliability aspects of maintenance. Linguistic description and fuzzy sets are developed for each of the indicators which are regarded as input parameters. Also domain experts are employed to develop inference rules for the aggregation process. The methodology of using fuzzy inference system for aggregating maintenance performance indicators is demonstrated with selected line sections of Trafikverket (Swedish Transport Administration). The resulting composite indicator gives a reliable quantification of the health condition of the asset and performance of maintenance within the period under consideration. This can be easily communicated and benchmarked within the organization of the infrastructure manager.
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| 34. |
- Famurewa, Stephen Mayowa, et al.
(författare)
-
Composite indicator for railway infrastructure management
- 2014
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Ingår i: Journal of Modern Transportation. - : Springer Science and Business Media LLC. - 2095-087X .- 2196-0577. ; 22:4, s. 214-224
-
Tidskriftsartikel (refereegranskat)abstract
- The assessment and analysis of railway infrastructure capacity is an essential task in railway infrastructure management carried out to meet the required quality and capacity demand of railway transport. For sustainable and dependable infrastructure management, it is important to assess railway capacity limitation from the point of view of infrastructure performance. However, the existence of numerous performance indicators often leads to diffused information that is not in a format suitable to support decision making. In this paper, we demonstrated the use of fuzzy inference system for aggregating selected railway infrastructure performance indicators to relate maintenance function to capacity situation. The selected indicators consider the safety, comfort, punctuality and reliability aspects of railway infrastructure performance. The resulting composite indicator gives a reliable quantification of the health condition or integrity of railway lines. A case study of the assessment of overall infrastructure performance which is an indication of capacity limitation is presented using indicator data between 2010 and 2012 for five lines on the network of Trafikverket (Swedish Transport Administration). The results are presented using customised performance dashboard for enhanced visualisation, quick understanding and relevant comparison of infrastructure conditions for strategic management. This gives additional information on capacity status and limitation from maintenance management perspective.
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| 35. |
- Famurewa, Stephen Mayowa, et al.
(författare)
-
Framework for performance based maintenance contracting
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The achievement of maintenance objectives is the pursuit of any maintenance department, as this will support the achievement of the overall business objectives. Using in-house or outsourced maintenance service provider is a decision which poses challenge to a lot of organisations. Should the decision be for outsourcing, the next concern is the selection of the most appropriate strategy suitable for the business environment, structure and philosophy. This article gives a detailed description of innovative maintenance contracting strategy namely performance based maintenance contracting. We have presented a structured framework as well as a monitoring tool for the mentioned outsourcing strategy to facilitate easy implementation.
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| 36. |
- Famurewa, Stephen Mayowa, et al.
(författare)
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Implementation of performance based maintenance contracting in railway industries
- 2013
-
Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 4:3, s. 231-240
-
Tidskriftsartikel (refereegranskat)abstract
- The achievement of maintenance objectives to support the overall business objectives is the pursuit of any maintenance department. Using in-house or outsourced maintenance service provider is a decision which poses challenge in the management of maintenance function. Should the decision be for outsourcing, the next concern is the selection of the most appropriate strategy suitable for the business environment, structure and philosophy. In an effort to improve maintenance function so as to deliver set objectives, some infrastructure managers (IM) adopted the approach of outsourcing maintenance function, giving larger responsibilities to maintenance service providers called contractors. Moreover, such change requires adequate attention to meet the pressing need of achieving the designed capacity of the existing railway infrastructure and also support a competitive and sustainable transport system. This paper discusses performance based railway infrastructure maintenance contracting with its issues and challenges. The approach of this article is review of literature and as well as synthesis of practices. A framework to facilitate the successful implementation of Performance Based Railway Infrastructure Maintenance (PBRIM) is presented. Also a performance monitoring system is proposed to assess the outcome and identify improvement potentials of the maintenance outsourcing strategy. A case study is given to demonstrate the monitoring of a typical maintenance activity that can be outsourced using this outsourcing strategy.
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| 37. |
- Famurewa, Stephen Mayowa, et al.
(författare)
-
Maintenance improvement: an opportunity for railway infrastructure capacity enhancement
- 2013
-
Konferensbidrag (refereegranskat)abstract
- The continually increasing demand on railway service in terms of the quantity and quality of both passenger and freight train operations is the core of the general railway capacity challenge. Moreover, this challenge has been the driver for some improvements in the technical system, traffic operation & management as well as maintenance process, although the room for improvement in the maintenance function is still large. An effective capacity management entails critical study of the three essential capacity parameters: infrastructure, traffic and operating parameters. To further explore the fundamentals of capacity management, this paper investigates some essential issues on railway infrastructure capacity. A review of the general railway infrastructure capacity challenge and management is presented, including some strategic measures to enhance capacity and quality of service of existing infrastructure. We have proposed maintenance improvement framework to explore the opportunity of improving the capacity situation on a network. This framework will facilitate the identification of both critical systems and activities with the largest impact on the capacity and also some root causes for critical system. The framework has suggested methodology to improve allocation and utilisation of track possession time, giving room for capacity expansion of existing railway infrastructure.
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| 38. |
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| 39. |
- Famurewa, Stephen Mayowa, et al.
(författare)
-
Railway Maintenance Performance : Perspective for Improvement
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Railway transport system is complex and requires effective maintenance to achieve the business goal of safe, economic and sustainable transportation of passengers and goods. The maintenance service either provided by internal or external agents is anticipated to reach specified objectives. The major objective of maintenance is to assure dependable infrastructure with the available resources, to meet operational target and other business objectives of infrastructure manager. This however requires continuous improvement through effective performance measurement and management. This article has identified some salient criteria or perspective of maintenance process that are essential to quantify the impact of past maintenance decisions and actions. The challenges of developing and implementing maintenance performance system in the railway industries are discussed. A synthesised system of maintenance performance measurement is also suggested, this emphasises the important performance aspects. A case study of a line section on the heavy haul line with mixed traffic, belonging to the Swedish railway network is presented as well to demonstrate the analytical perspective of performance indicators. This will enhance the identification of improvement opportunities in railway infrastructure maintenance. Such improvements will support the overall business goal of meeting service quality and capacity target of infrastructure manager.
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| 40. |
- Famurewa, Stephen Mayowa, et al.
(författare)
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RAM Modelling of Railway Operational Sections : A Case Study from the Iron Ore Line
- 2014
-
Ingår i: Proceedings of the Second International Conference on Railway Technology. - Kippen : Civil-Comp Press. - 9781905088591
-
Konferensbidrag (refereegranskat)abstract
- Railway infrastructure is a linearly distributed asset which has different hierarchical levels such as lines, operational sections, assemblies, modules and maintainable components. The management and performance evaluation of the entire system is done at suitable hierarchical level for efficiency and practicality. It is ideal to assess the integrity as well as the reliability, availability and maintainability (RAM) of the infrastructure on the level of operational sections which are established technical divisions used for traffic operational management by infrastructure administrations. There are several approaches that are used to evaluate the RAM characteristics of a system. This paper presents an approach for RAM simulation of railway operational sections using an event based simulation tool with the Monte Carlo technique. Theinput data used in the RAM modelling includes: historical maintenance and failure data between 2010 and 2012, planned train mission and possible preventive maintenance plans. The outcome of the simulation is the estimation of different RAM parameters over a period of one year. Amongst the parameters are: the expected number of failures and the downtime per operational section, states of each operational section and the overall dependability measure of the line in terms of the success of the planned traffic. These parameters are integrity measures of the asset which can be used for traffic simulation for effective management of traffic. They are also useful for logistic support planning that is required for cost effective and highly dependable infrastructure management.
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| 41. |
- Farinha, José Manuel Torres, et al.
(författare)
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Certification of maintenance providers: a competitive advantage
- 2013
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Ingår i: Journal of Quality in Maintenance Engineering. - : Emerald. - 1355-2511 .- 1758-7832. ; 19:2, s. 144-156
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose – The purpose of this paper is to synthesize some relevant norms, namely European norms (EN), to the maintenance field. Design/methodology/approach – The methodology is based on the conjunction of the most relevant norms to the maintenance field that represent a coherent set of tools to aid maintenance activity and maintenance companies to achieve a new level of competitiveness. Findings – Until now, the companies have not given relevance to specific certifications, such as PAS 55 or NP4492. But, with the increase of competitiveness and the market more and more exigent, it is necessary to introduce this new paradigm to raise the maintenance activity at an upper level. Practical implications – The approach presented in the paper constitutes a base for an upper level of competitiveness among companies, based on common standards that make the maintenance activity more exigent and transparent. Originality/value – The paper presents a conjunction among standards, including the newest ones, that constitutes a new vision for maintenance providers, representing a definitive contribution for a new positioning of the maintenance market.
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| 42. |
- Fuqing, Yuan, et al.
(författare)
-
A comparative study of artificial neural networks and support vector machine for fault diagnosis
- 2013
-
Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 9:1, s. 49-60
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Tidskriftsartikel (refereegranskat)abstract
- Fault detection is a crucial step in condition based maintenance requiring. The importance of fault diagnosis necessitates an efficient and effective failure pattern identification method. Artificial Neural Networks (ANN) and Support Vector Machines (SVM) emerging as prospective pattern recognition techniques in fault diagnosis have been showing its adaptability, flexibility and efficiency. Regardless of variants of the two techniques, this paper discusses the principle of the two techniques, and discusses their theoretical similarity and difference. Eventually using the commonest ANN, SVM, a case study is presented for fault diagnosis using a wide used bearing data. Their performances are compared in terms of accuracy, computational cost and stability
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| 43. |
- Fuqing, Yuan, et al.
(författare)
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A cost model for repairable system considering multi-failure type over finite time horizon
- 2011
-
Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 7:2, s. 186-194
-
Tidskriftsartikel (refereegranskat)abstract
- In general, downtime of a system can be attributed due to multiple failure categories and repair costs for each failure categories can be different. Many of these failure types are repaired to a state which can be called as bad as old and such repair actions are termed as “minimal repair”. Many system or components are replaced after a certain number of such minimal repair actions. In this study, we intend to prove that if the system failure process can be described by NHPP (Non Homogenous Poisson Process), then each failure category can also be modelled by NHPP. Based on this, a cost model is developed by using the decomposition of the NHPP and renewal theory. Using the cost model, a model is developed to obtain the optimal number of minimum repair action every failure category. Since it is not possible to find any analytical solution, solution to the renewal function, an approximate approach is introduced to obtain numerical solution. Finally, a numerical example is presented to demonstrate the method.
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| 44. |
- Fuqing, Yuan, et al.
(författare)
-
A general imperfect repair model considering time-dependent repair effectiveness
- 2012
-
Ingår i: IEEE Transactions on Reliability. - 0018-9529 .- 1558-1721. ; 61:1, s. 95-100
-
Tidskriftsartikel (refereegranskat)abstract
- Kijima I and Kijima II models are two important imperfect repair models in literature. These two models use one constant parameter to represent the degree of repair, which is called Repair Effectiveness (RE) in this paper. We developed a more general imperfect repair model by extending the constant RE to a time-dependent function based on the virtual age process, where the Kijima models are special cases of the new model. A simulation method is developed to estimate the cumulative number of failures for the new model, and a Bayesian inference method is proposed to select the best imperfect repair model. Finally, to demonstrate the new model, a numerical example is provided. From this example, the new model shows a more accurate mean and a narrower confidence interval than that of the Non-Homogeneous Poisson Processes, and Kijima I and Kijima II models.
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| 45. |
- Fuqing, Yuan, et al.
(författare)
-
An adaptive multiple kernel method-based support vector machine used for classication
- 2013
-
Ingår i: International Journal of Condition Monitoring. - : British Institute of Non-Destructive Testing (BINDT). - 2047-6426. ; 3:1, s. 8-15
-
Tidskriftsartikel (refereegranskat)abstract
- Classification is an important technique used for condition monitoring. Extensive research has been carried out on classification and numerous techniques have been developed. The support vector machine (SVM) is one of these techniques; it has excellent classification capacity and is widely used. The effectiveness of the SVM depends on the selection of the kernel function, so to maximise performance this paper proposes using an adaptive multiple kernel SVM (AMK-SVM). Using AMK, many heterogeneous features, such as continuous, categorical, logical etc, can be merged. Instead of predefining the parameters of kernel functions as with other multiple kernel SVMs, this method can adapt its parameters to data automatically through kernel alignment. The paper offers two numerical examples: one with benchmarking data to test the feasibility and performance of the approach (for this case a two-layer neural network and two single kernel SVMs are applied to the same datasets to compare their performance with the AMK-SVM); the other example uses the AMK-SVM to discriminate a healthy bearing from a defective bearing
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| 46. |
- Fuqing, Yuan, et al.
(författare)
-
Anomaly detection using support vector machines on overhead contact wire
- 2013
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes an anomaly detection method on the Overhead Contact Wire (OCW) in electrified railway system. The fundamental basic of contact wire is described. Their mechanical property and thermal property are discussed. The principle of the current collection through the overhead wire is described in brief. Some classical mechanic dynamic models between the pantograph and overhead contact wire are presented. Concentrating on the anomaly detection using vertical acceleration signal, this paper proposes a support vector regression based method to detect the anomaly detection on the surface of the overhead contact wire. The Support Vector Regression (SVR) is used to model the dependency between vertical acceleration and the other factor such as uplift, train speed, height of the wire. Correlation is used to find the significant factors which influence the vertical acceleration. The SVR model is used to de-trend the vertical acceleration signal. The statistical model is proposed to find the anomaly points on the contact wire.
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| 47. |
- Fuqing, Yuan, et al.
(författare)
-
Complex system reliability evaluation using support vector machine
- 2010
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Support Vector Machine (SVM) is a data mining technique that has been successfully used in classification problems, starting from a known training data set (TDS). In systems modeled as networks, SVM has been used to classify the state of a network as failed or operating and jointly combined in a Monte Carlo sampling approach to approximate the network reliability. The analytical expression of the binary function (failed/operating) produced by SVM is difficult to be understood, since it generally involves the evaluation of non-linear operators, which consider a subset of the TDS, called Support Vectors (SV) and sampled system states. In this paper a different approach is proposed to assess system reliability. Information about path and cut sets is obtained directly from SV, without considering the analytical expression of the binary function produced by SVM. From here the system reliability is approximated directly. Several examples illustrate the approach.
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| 48. |
- Fuqing, Yuan, et al.
(författare)
-
Complex system reliability evaluation using support vector machine for incomplete data-set
- 2011
-
Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 7:1, s. 32-42
-
Tidskriftsartikel (refereegranskat)abstract
- Support Vector Machine (SVM) is an artificial intelligence technique that has been successfully used in data classification problems, taking advantage of its learning capacity. In systems modelled as networks, SVM has been used to classify the state of a network as failed or operating to approximate the network reliability. Due to the lack of information, or high computational complexity, the complete analytical expression of system states may be impossible to obtain, that is to say, only incomplete data-set can be obtained. Using these incomplete data-sets, depending on amount of missed data-set, this paper proposes two different approaches named rough approximation method and simulation based method to evaluate system reliability. SVM is used to make the incomplete data-set complete. Simulation technique is also employed in the so called simulation based approximation method. Several examples are presented to illustrate the approaches.
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| 49. |
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| 50. |
- Fuqing, Yuan, et al.
(författare)
-
Failure diagnosis of railway assets using support vector machine and ant colony optimization method
- 2012
-
Ingår i: International Journal of COMADEM. - 1363-7681. ; 15:2, s. 3-10
-
Tidskriftsartikel (refereegranskat)abstract
- Support Vector Machine (SVM) is an excellent technique for pattern recognition. This paper uses a multi-class SVM as a classifier to solve a multi-class classification problem for fault diagnosis. As the pre-defined parameters in the SVM influence the performance of the classification, this paper uses the heuristic Ant Colony Optimization (ACO) algorithm to find the optimal parameters. This multi-class SVM and ACO are applied to the fault diagnosis of an electric motor used in a railway system. A case study illustrates how efficient the ACO is in finding the optimal parameters. By using the optimal parameters from the ACO, the accuracy of the performed diagnosis on the electric motor is found to be highest.
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