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Tianyan Liu,Xiangyang Xu,Minghui Zhang,Runbo Zhang,Yue Wu,Hongzhi Ji,Yanfang Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
Under the engaging process, excessive temperature of clutch plates may lead to thermal failure. Existing research has failed to find the hot spot and the radial temperature difference real-timely. They also neglected the influence of dynamic sliding process and hydraulic characteristics. Thus, a multi-domain dynamic model of the whole clutch was proposed, involving the mechanical dynamics, the hydraulic dynamics and thermics. With the thermal resistance network method, the real-time axial and radial temperature prediction of clutch plates was realized. The highest temperature occurs on the friction pairs of axial middle and the maximum value occurs on the radial 5th mass. Compared with the results by FEM, the deviation is about 6.5 %, but the time duration is reduced significantly. Furthermore, the influence of the outer hub vibration (160 Hz, 0.2 Hz) on the dynamic characteristics was discussed. This work was tested to be an effective and good basis for the health prediction of wet clutches.
Jiang Tianyan,Zhang Tao,Li Yang,Zeng Shuai,Liu Qiang,Bi Maoqiang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4
The safe operation of power transformer is vital to the reliability of modern power network. The bushing is a key component of transformer that serves to connect the transformer windings to the transmission lines. Due to its intricate structure and severe operating conditions, the bushing is among the most frequent cause of transformer failure. Therefore, it is essential to monitor the condition of transformer bushing for maintaining the safe and stable operation of grid. In this paper, we propose a graphene piezoresistive pressure sensor based on handkerchief paper (GHPPS) to monitor the internal pressure of transformer bushing. The GHPPS possesses a highly porous structure and a fibrous tissue, and exhibits a superb sensitivity to the variations of bushing internal pressure. Moreover, we compared the sensitivity and conductivity of the sensors with different paper layers. The GHPPS with 8 layers owns the highest sensitivity (15.6 kPa−1), the smallest response time (60 ms) and recovery time (75 ms), and the best stability. In addition, a hierarchical alarm device is used to test the monitoring capability of GHPPS at different pressure levels. The results prove that the GHPPS is a promising tool for monitoring bushing conditions.
The drag characteristics prediction of multi-plate frictional wet clutches in vehicle transmissions
Minghui Zhang,Yanfang Liu,Tianyan Liu,Xiangyang Xu,Jin Xu,Yudong Zhang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
The multi-plate frictional wet clutch is one of the most important components in automatic transmissions. With the increasing of the rotational speed, the phenomena is tested that the drag torque firstly increases to the peak torque, and then decreases to a lower level and maintains within a certain range, and finally increases rapidly again. A fluid-structure coupled model of the whole wet clutch was established. The simulation results show that the pressure distribution is obviously nonuniform either on the frictional surface or between two sides of the clutch plate. The nonuniform pressure would cause the axial and deflection motion and so the impact would occur, which is the main reason for the drag torque’s increasing under high rotational speed. Based on the simulated results, a prediction model was built with the direct artificial neural network method. The test results show that the drag characteristics prediction model is effective and fast.
Qing Jiao,Libo Zou,Peng Liu,Qian Xu,Yifei Zhang,Ying Yu,Lu Zou,Tianyan Chi,Xuefei Ji 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.10
Xanthoceraside, a saponin extracted from the husks of Xanthoceras sorbifolia Bunge, suppresses inflammation and oxidative stress. However, the antitumor properties of xanthoceraside as well as its mechanism of action remain unclear. Therefore, we proposed to investigate its potential anticancer property. In this study, the viability of cells was measured by the MTT assay. Cell cycle and mitochondrial membrane potential were measured by flow cytometry, and the expressions of procaspase-9, procaspase-3, Cyto.c, Apaf-1, Bcl-2, Bcl-xL, Bad, p53, and IGF-1R/Raf/MEK/ERK were tested by Western blotting. Xanthoceraside significantly inhibited the proliferation of human melanoma A375.S2 cells in a concentration- and time-dependent manner but did not impair the viability of normal cells (peripheral blood mononuclear cells). Further analysis revealed that xanthoceraside induced apoptosis by activating caspase-3 and caspase-9 in a time-dependent manner through the mitochondrial pathway but did not activate caspase-8 in the cells. In addition, xanthoceraside inhibited the expression of the insulin-like growth factor-1 receptor (IGF-1R), which is an important prosurvival, antiapoptotic signaling growth factor receptor that is frequently overexpressed in cancer cells and used as a therapeutic target for multiple cancers. Interestingly, xanthoceraside also decreased the expression of Raf, p-MEK, and p-ERK, the downstream effectors of IGF-1R. Taken together, these findings indicate that xanthoceraside induces apoptosis through a mitochondria-mediated apoptotic pathway, which is induced by the downregulation of IGF-1R/Raf/MEK/ERK cascades in A375.S2 cells.