## 5 Conclusions
This research was funded by the National Key Research and Development Program of China (Grant number 2016 YFC0600900), the Yue Qi Distinguished Scholar Project of China University of Mining & Technology(Beijing) (Grant number 800015Z1145), the National Natural Science Foundation of China (Grant number U1361127), the Fundamental Research Funds for the Central Universities (Grant number 00/800015 HJ), the Education and Scientific Research Foundation of Education Department of Fujian Province for Middle-aged and Young Teachers (Grant number JAT170352), the Foundation of Department of Education of Guangdong Province (Grant number 2017 KCXTD015), and the Open Foundation of Digital Signal and Image Processing Key Laboratory of Guangdong Province (Grant number 2017 GDDSIPL-01). The APC was funded by the National Natural Science Foundation of China (Grant number U1361127). The authors would like to thank for the supports of all the fundings. The authors would also like to thank Editage [www.editage.cn] for English language editing. The authors declare no conflict of interest. * [PERSON] and [PERSON] (1978) [PERSON], [PERSON]; [PERSON] Hydrodynamic lubrication of ball-bearing cage pockets. _ARCHIVE J. Mech. Eng. Sci._**1978**, _20_, 11-20. [CrossRef]
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