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RISS 인기검색어
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- 저자 : Xiangyu Xie (검색결과 4 건)
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Analysis of skid damage to cylindrical roller bearing of mainshaft of aeroengine
Xiangyu Xie,Jin Xu,Jun Luo 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8
Skid damage to mainshaft bearings on aeroengines severely reduces aircraft reliability. In this study, a batch of cylindrical roller bearings extracted from mainshaft of inservice aeroengines with, skid damage after a certain service period, were collected, and damage features of the bearings were characterized and compared with those of the undamaged bearings and the new ones. Microscopic feature evaluation, elemental analysis as well as the composition distribution of the bearings were conducted using scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, transmission electron microscopy and surface profilometry. Analysis results reveal that skidding itself is a very complex process initiated by the action of different mechanisms, and manifest in different wear types. The damage mechanism of skid damaged bearings was the joint consequence of abrasive wear, oxidation wear and delamination wear. All the aforementioned damage and wear led to severe aircraft failures.
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( Xiangyu Liu ),( Mowen Xie ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2
A geographic information systems(GIS)-based slope stability analysis method is proposed based on the assumption of normal stress distribution acting on the slip surface. first, a three-dimensional slopestability analysis model based on grid column units is established. then, four equilibrium equations are derived under limit equilibrium condition. the normal stress distribution acting on the slip surface is analysed to construct a reasonable normal stress distribution approximatin function for solving the safety factor. moreover, a GIS-based extension module is developed. the accuracy and feasibility of the module are vefified by three typical cases.
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Hao Jiancheng,Li Zhaoyu,Li Xiangyu,Xie Fubao,He Dong,Tang Kai 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.5
When machining a complex freeform part, using a non-spherical tool could significantly improve the machining efficiency, as one can adaptively adjust the tool posture to maximize its contact area with the part surface. However, since adjusting the tool posture requires changing the tool orientation, a five-axis machine tool is needed, which is extremely expensive as compared to a conventional three-axis machine tool. Moreover, for a complex freeform surface with high curvature variation, to match its curvature change, the tool axis has to drastically change accordingly, thus inducing high velocity and acceleration on the machine tool’s rotary axes. To address these issues, in this paper we propose a partition-based 3 + 2-axis strategy for machining a general complex freeform surface with a non-spherical tool. As only a finite small number of distinct tool orientations are needed for 3 + 2-axis machining, an indexed three-axis machine tool suffices, thus relieving the need of an expensive five-axis machine tool. In addition, the much-increased rigidity of the three linear axes of the machine tool will greatly improve the kinematics and dynamics of the machine tool and thus enhance the machining accuracy. Experiments in both computer simulation and physical machining are carried out, whose results confirm that, when compared to using a conventional spherical cutter, by using a non-spherical cutter and adaptively adjusting the contacting tool posture and the feed direction, significant improvement in machining efficiency could be achieved, e.g., more than 50% achieved in our experiments.
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Xiang-Hong Xu,Yuanhui Jia,Xinyao Zhou,Dandan Xie,Xiaojie Huang,Linyan Jia,Qian Zhou,Qingliang Zheng,Xiangyu Zhou,Kai Wang,Li-Ping Jin 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-
Preeclampsia is a pregnancy-specific disorder that is a major cause of maternal and fetal morbidity and mortality with a prevalence of 6–8% of pregnancies. Although impaired trophoblast invasion in early pregnancy is known to be closely associated with preeclampsia, the underlying mechanisms remain elusive. Here we revealed that lysyl oxidase (LOX) and LOX-like protein 2 (LOXL2) play a critical role in preeclampsia. Our results demonstrated that LOX and LOXL2 expression decreased in preeclamptic placentas. Moreover, knockdown of LOX or LOXL2 suppressed trophoblast cell migration and invasion. Mechanistically, collagen production was induced in LOX- or LOXL2-downregulated trophoblast cells through activation of the TGF-β1/Smad3 pathway. Notably, inhibition of the TGF-β1/Smad3 pathway could rescue the defects caused by LOX or LOXL2 knockdown, thereby underlining the significance of the TGF-β1/ Smad3 pathway downstream of LOX and LOXL2 in trophoblast cells. Additionally, induced collagen production and activated TGF-β1/Smad3 were observed in clinical samples from preeclamptic placentas. Collectively, our study suggests that the downregulation of LOX and LOXL2 leading to reduced trophoblast cell migration and invasion through activation of the TGF-β1/Smad3/collagen pathway is relevant to preeclampsia. Thus, we proposed that LOX, LOXL2, and the TGF-β1/Smad3/collagen pathway can serve as potential markers and targets for clinical diagnosis and therapy for preeclampsia.
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