[1] Ma C Y, Chen B, Tan C W et al. Characteristics of droplet transfer, molten pool formation, and weld bead formation of oscillating laser hot-wire tungsten inert gas hybrid welding[J]. Journal of Laser Applications, 33, 012027(2021).

[2] Chen S X, Liu S Y, Zhang H et al. Study on correlation between plasma property and weld penetration in laser-arc hybrid welding[J]. Acta Armamentarii, 38, 978-985(2017).

[3] Ye G W, Liu Q W, Fan X A et al. Effect of droplet transition on weld surface formation of laser-MIG hybrid welding[J]. Chinese Journal of Lasers, 49, 0802012(2022).

[4] Zhou J, Shao C D, Cui H C et al. Plasma coupling behavior of laser-arc hybrid welding in groove[J]. Chinese Journal of Lasers, 49, 0202006(2022).

[5] Frostevarg J. Factors affecting weld root morphology in laser keyhole welding[J]. Optics and Lasers in Engineering, 101, 89-98(2018).

[6] Qi Y, Chen G Y, Deng S L et al. Periodic root humps in thick-plate laser welding using steady electromagnetic force[J]. Journal of Materials Processing Technology, 273, 116247(2019).

[7] Zou D M, Qi J G, Zhao L et al. Effect of welding speed on bead appearance and low-temperature impact toughness in laser-arc hybrid welding[J]. Chinese Journal of Lasers, 49, 0802014(2022).

[8] Zhang H Q, Jiang M, Chen X et al. Investigation of weld root defects in high-power full-penetration laser welding of high-strength steel[J]. Materials, 15, 1095(2022).

[9] Powell J, Ilar T, Frostevarg J et al. Weld root instabilities in fiber laser welding[J]. Journal of Laser Applications, 27, S29008(2015).

[10] Zhang R L, Tang X H, Xu L D et al. Study of molten pool dynamics and porosity formation mechanism in full penetration fiber laser welding of Al-alloy[J]. International Journal of Heat and Mass Transfer, 148, 119089(2020).

[11] Zhang M J, Liu T T, Hu R Z et al. Understanding root humping in high-power laser welding of stainless steels: a combination approach[J]. The International Journal of Advanced Manufacturing Technology, 106, 5353-5364(2020).

[12] Wang L, Gao X D, Kong F R. Keyhole dynamic status and spatter behavior during welding of stainless steel with adjustable-ring mode laser beam[J]. Journal of Manufacturing Processes, 74, 201-219(2022).

[13] Gao X D, Ding D, Bai T X et al. Weld-pool image centroid algorithm for seam-tracking vision model in arc-welding process[J]. IET Image Processing, 5, 410-419(2011).

[14] Chen J Q, Wang T, Gao X D et al. Real-time monitoring of high-power disk laser welding based on support vector machine[J]. Computers in Industry, 94, 75-81(2018).

[15] Wang T, Gao X D, Seiji K et al. Study of dynamic features of surface plasma in high-power disk laser welding[J]. Plasma Science and Technology, 14, 245-251(2012).

[16] Fan X A, Gao X D, Huang Y H et al. Online detection of keyhole status in a laser-MIG hybrid welding process[J]. Metals, 12, 1446(2022).

[17] Gao X D, Zhang Y X. Monitoring of welding status by molten pool morphology during high-power disk laser welding[J]. Optik, 126, 1797-1802(2015).

[18] Fan X A, Gao X D, Zhang N F et al. Monitoring of 304 austenitic stainless-steel laser-MIG hybrid welding process based on EMD-SVM[J]. Journal of Manufacturing Processes, 73, 736-747(2022).

[19] Feng Y Z, Gao X D, Zhang Y X et al. Simulation and experiment for dynamics of laser welding keyhole and molten pool at different penetration status[J]. The International Journal of Advanced Manufacturing Technology, 112, 2301-2312(2021).

[20] Zhang Y X, Han S W, Cheon J et al. Effect of joint gap on bead formation in laser butt welding of stainless steel[J]. Journal of Materials Processing Technology, 249, 274-284(2017).

[21] Chen G Y, Xia H L, Zhou C et al. Study on the mechanism of root humping of laser welding with high power fiber laser[J]. Chinese Journal of Lasers, 42, 0203004(2015).

[22] Gao X D, Mo L, You D Y et al. Tight butt joint weld detection based on optical flow and particle filtering of magneto-optical imaging[J]. Mechanical Systems and Signal Processing, 96, 16-30(2017).

[23] Mu Q, Wei Y Y, Li J et al. Improved Retinex low illumination image enhancement algorithm research[J]. Journal of Harbin Engineering University, 39, 2001-2010(2018).

[24] Lu Z M, Liu Q T, Fan D M et al. Visual image enhancement based on the MSR with luminance division[J]. Journal of Huazhong University of Science and Technology (Natural Science Edition), 39, 99-102(2011).

[25] Wang M, Chen W Y, Li X D. Hand gesture recognition using valley circle feature and Hu's moments technique for robot movement control[J]. Measurement, 94, 734-744(2016).

[26] Zhang Z J, Ma J E, Li X F et al. Insulator fault detection based on deep learning and Hu invariant moments[J]. Journal of the China Railway Society, 43, 71-77(2021).

[27] Shamsuddin S M, Sulaiman M N, Darus M. Invarianceness of higher order centralised scaled-invariants undergo basic transformations[J]. International Journal of Computer Mathematics, 79, 39-48(2002).

[28] Gong W F, Wang Y Z, Chen H et al. Anomaly diagnosis for navigation sensors of unmanned autonomous vehicles based on deep learning[J]. Journal of Mechanical Engineering, 57, 268-278(2021).

[29] Yu H D, Mi Q S, Zhao D et al. Optical fiber perimeter intrusion pattern recognition based on 1D-CNN[J]. Acta Photonica Sinica, 50, 0906003(2021).