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Modification of correlation optimized warping method for position alignment of condition measurements of linear assets
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.ORCID iD: 0000-0001-5785-1242
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.ORCID iD: 0000-0002-3266-2434
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.ORCID iD: 0000-0001-7083-4009
Trafikverket, Luleå, Sweden.
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2022 (English)In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 201, article id 111707Article in journal (Refereed) Published
Abstract [en]

This paper proposes a modification to a well-known alignment method, correlation optimized warping (COW), to improve the efficiency of the method and reduce the positional errors in the measurements of linear assets. The modified method relaxes the restrictions of COW in aligning the start and end of datasets and decreases the computational time. Furthermore, the method takes advantage of the interdependencies between simultaneously measured channels to overcome the missing data problem. A case study on railway track geometry measurements was conducted to implement the proposed method and assess its performance in reducing the positioning inaccuracy of the measurements. The findings revealed that the modified method could decrease the positional errors of defects to below 25 cm in 94% of the trials.

Place, publisher, year, edition, pages
Elsevier, 2022. Vol. 201, article id 111707
Keywords [en]
Position alignment, correlation optimized warping, data quality, linear assets, positional error, condition measurements
National Category
Software Engineering Other Mechanical Engineering
Research subject
Operation and Maintenance
Identifiers
URN: urn:nbn:se:ltu:diva-92409DOI: 10.1016/j.measurement.2022.111707ISI: 000871195400003Scopus ID: 2-s2.0-85135916407OAI: oai:DiVA.org:ltu-92409DiVA, id: diva2:1686463
Funder
Swedish Transport AdministrationLuleå Railway Research Centre (JVTC)
Note

Validerad;2022;Nivå 2;2022-08-16 (sofila);

Funder: In2Smart II project (881574 EU Shift2Rail)

Available from: 2022-08-10 Created: 2022-08-10 Last updated: 2023-10-03Bibliographically approved
In thesis
1. Leveraging Data-Driven and Alignment Techniques for Optimal Railway Track Maintenance Scheduling
Open this publication in new window or tab >>Leveraging Data-Driven and Alignment Techniques for Optimal Railway Track Maintenance Scheduling
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The railway infrastructure plays a pivotal role in fostering economic growth and poverty alleviation. Over time, these infrastructures deteriorate due to aging and usage, compromising their functionality. Given their crucial socioeconomic significance and vast scale, ensuring their functionality and availability is paramount. Thus, an effective condition-based maintenance program is essential to restore reliability, facilitate cost-effective restoration, and enable continued benefits.

Track is a critical railway component susceptible to degradation from traffic loading, resulting in deviations from designated geometry parameters. Such degradation jeopardizes safety, availability, and travel quality. Developing an effective tamping regime emerges as a vital maintenance measure to control degradation and restore track geometry to acceptable standards. An optimal maintenance schedule becomes imperative to minimize costs, enhance track availability and capacity, and ensure safety.

Achieving efficient tamping scheduling necessitates accurate prediction of geometry degradation, accounting for tamping effects, and modeling the evolution of single defects. However, uncontrolled shifts in geometry measurements from different inspections—known as positional errors—can misplace defects and distort their evolution analysis. Therefore, precise alignment of geometry measurements is vital to eliminate such positional errors.

The purpose of this research was to streamline maintenance scheduling through leveraging track geometry measurements for modeling and prediction. Firstly, a study addressed alignment through evaluating and comparing four methods—Cross-Correlation Function (CCF), Recursive alignment by fast Fourier transform (RAFFT), Correlation optimized warping (COW), and Dynamic Time Warping (DTW). Furthermore, a combined RAFFT-COW method was proposed, overcoming their limitations. Comparison revealed COW aligned datasets satisfactorily without altering their shape but could not align endpoints precisely. The combined method effectively aligned datasets even when the datasets were stretched or compressed. Secondly, a modified COW (MCOW) addressed accurate and efficient alignment. MCOW surpassed COW's restrictions and reduced alignment time. To enhance robustness, MCOW with channel fusion (MFCOW) combined data from different channels, significantly reducing positional errors. Thirdly, a multi-objective approach proposed aimed at reducing positional errors in geometry measurements of track as a linear asset. Accordingly, recursive segment-wise peak alignment (RSPA) and MCOW were evaluated and compared. Furthermore, a novel rule-based approach proposed which prevented data loss during alignment, preserving all the single defects. In addition, the results revealed that RSPA excelled in aligning peaks, while MCOW proved efficient for datasets with equal priority data points.

Finally, an optimization model minimized track geometry maintenance costs through tamping scheduling. Key track quality indicators, including the standard deviation of the longitudinal level and single defects and the impact of preventive/corrective tamping on these indicators were integrated. Results showcased the influence of fixed maintenance window costs and maintenance cycle intervals on tamping expenses. The model's validity was confirmed through interactions with experienced practitioners from prominent railway infrastructure and maintenance entities.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2023
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Railway tracks, degradation, maintenance, tamping, track geometry, planning and scheduling, alignment
National Category
Transport Systems and Logistics
Research subject
Operation and Maintenance Engineering
Identifiers
urn:nbn:se:ltu:diva-101556 (URN)978-91-8048-389-6 (ISBN)978-91-8048-390-2 (ISBN)
Public defence
2023-12-20, C305, Luleå tekniska universitet, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2023-10-04 Created: 2023-10-03 Last updated: 2023-11-29Bibliographically approved

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Khosravi, MahdiSoleimanmeigouni, ImanAhmadi, Alireza

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