{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T04:57:12Z","timestamp":1789621032174,"version":"build-2803163510"},"reference-count":45,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2018,2,27]],"date-time":"2018-02-27T00:00:00Z","timestamp":1519689600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"RGC Theme-based Research Fund","award":["T32-101\/15-R"],"award-info":[{"award-number":["T32-101\/15-R"]}]},{"name":"Technology Plan Project of Sichuan Province","award":["2017JY0127"],"award-info":[{"award-number":["2017JY0127"]}]},{"name":"Technology Plan Project of Sichuan Province","award":["2016JY0047"],"award-info":[{"award-number":["2016JY0047"]}]},{"name":"National Key R&amp;D Program of China","award":["2016YFB1200401"],"award-info":[{"award-number":["2016YFB1200401"]}]},{"name":"the Key Scientific Research Fund of Xihua University","award":["z1620305"],"award-info":[{"award-number":["z1620305"]}]},{"name":"the Key Lab. Project of Sichuan Province","award":["szjj2016-015"],"award-info":[{"award-number":["szjj2016-015"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Railway axle bearings are one of the most important components used in vehicles and their failures probably result in unexpected accidents and economic losses. To realize a condition monitoring and fault diagnosis scheme of railway axle bearings, three dimensionless steadiness indexes in a time domain, a frequency domain, and a shape domain are respectively proposed to measure the steady states of bearing vibration signals. Firstly, vibration data collected from some designed experiments are pre-processed by using ensemble empirical mode decomposition (EEMD). Then, the coefficient of variation is introduced to construct two steady-state indexes from pre-processed vibration data in a time domain and a frequency domain, respectively. A shape function is used to construct a steady-state index in a shape domain. At last, to distinguish normal and abnormal bearing health states, some guideline thresholds are proposed. Further, to identify axle bearings with outer race defects, a pin roller defect, a cage defect, and coupling defects, the boundaries of all steadiness indexes are experimentally established. Experimental results showed that the proposed condition monitoring and fault diagnosis scheme is effective in identifying different bearing health conditions.<\/jats:p>","DOI":"10.3390\/s18030704","type":"journal-article","created":{"date-parts":[[2018,2,27]],"date-time":"2018-02-27T14:18:08Z","timestamp":1519741088000},"page":"704","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":38,"title":["EEMD-Based Steady-State Indexes and Their Applications to Condition Monitoring and Fault Diagnosis of Railway Axle Bearings"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5641-6791","authenticated-orcid":false,"given":"Cai","family":"Yi","sequence":"first","affiliation":[{"name":"School of Automobile and Transportation, Xihua University, Chengdu 610039, China"},{"name":"Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4872-4860","authenticated-orcid":false,"given":"Dong","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei","family":"Fan","sequence":"additional","affiliation":[{"name":"Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kwok-Leung","family":"Tsui","sequence":"additional","affiliation":[{"name":"Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianhui","family":"Lin","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,2,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"10991","DOI":"10.3390\/s150510991","article-title":"Faults Diagnostics of Railway Axle Bearings Based on IMF\u2019s Confidence Index Algorithm for Ensemble EMD","volume":"15","author":"Yi","year":"2015","journal-title":"Sensors"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"216","DOI":"10.1016\/j.engfailanal.2015.02.008","article-title":"Observing early stage rail bearing damage","volume":"56","author":"Symonds","year":"2015","journal-title":"Eng. 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