1. Yang, Y.X.: Research on Preparation and Modification of Polyimide Based Porous Oil-bearing Material, pp. 4–5. Harbin Institute of Technology, Harbin (2017)
2. Zhao, H.J.: Study on Improving the Performance of Rolling Bearing at Starved Lubrication by Porous PI, pp. 1–2. Nanjing Aerospace University, Nanjing (2017)
3. Wang, Y.L., Zhang, F.: Calculation of porous copper’s porosity by SEM method. Initiating Explos. Device 06, 49–53 (2012)
4. Deng, L.H., Wang, R., Chen, Y.Y.: Application of image processing system of image J based on electronic scanning in porous materials. Sens. Microsyst. 31(05), 150–152 (2012)
5. Mumford, D., Shah, J.: Optimal approximations by piecewise smooth functions and associated variational problems. Commun. Pure Appl. Math. 42, 577–685 (1989)