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The nonlinear effects of flexible pins on wind turbine gearboxes
Xiangyang Xu,Shaojiang Dong,Jiayuan Luo,Tianhong Luo 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8
The structure of flexible pin-type planetary gear systems used in wind turbine gearboxes can improve the load sharing ability of planetswhile saving space unlike straddle-type carriers. However, the nonlinear dynamic characteristic of this type of system is not fully developed. This work presents a coupled lumped-parameter dynamic model to demonstrate nonlinear effects. Gear contact loss nonlinearityand bearing clearance nonlinearity are integrated into this dynamical model, and the effects of flexible pins on the nonlinear dynamicresponses are discussed. The conclusions made are as follows: lower flexible pin stiffness can significantly reduce nonlinear effects;when pin stiffness is increased, contact loss still occurs in positions of strong vibration even if the planet gear bearings have higher ordersof magnitude of tangential load in the wind turbine gearbox; dynamic response peaks are asymmetric with a frequency sweep; only leftoblique "Soft" jumps occur, and the right oblique “Hard” jump phenomena rarely occur; planet gear supporting the bearing clearanceexists; and vibration chaos occurs in positions of strong vibration.
Automatic Detection of Dead Trees Based on Lightweight YOLOv4 and UAV Imagery
Yuanhang Jin,Maolin Xu,Jiayuan Zheng 한국정보처리학회 2023 Journal of information processing systems Vol.19 No.5
Dead trees significantly impact forest production and the ecological environment and pose constraints to thesustainable development of forests. A lightweight YOLOv4 dead tree detection algorithm based on unmannedaerial vehicle images is proposed to address current limitations in dead tree detection that rely mainly oninefficient, unsafe and easy-to-miss manual inspections. An improved logarithmic transformation method wasdeveloped in data pre-processing to display tree features in the shadows. For the model structure, the originalCSPDarkNet-53 backbone feature extraction network was replaced by MobileNetV3. Some of the standardconvolutional blocks in the original extraction network were replaced by depthwise separable convolutionblocks. The new ReLU6 activation function replaced the original LeakyReLU activation function to make thenetwork more robust for low-precision computations. The K-means++ clustering method was also integratedto generate anchor boxes that are more suitable for the dataset. The experimental results show that the improvedalgorithm achieved an accuracy of 97.33%, higher than other methods. The detection speed of the proposedapproach is higher than that of YOLOv4, improving the efficiency and accuracy of the detection process.
Liu Yize,Qiu Guanzhen,Luo Yinzhou,Li Shanshan,Xu Yeqiu,Zhang Yuanzhuang,Hu Jiayuan,Li Peifeng,Pan Hai,Wang Yong 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
As the most prevalent bone tumor in children and adolescents, the pathogenesis and metastasis of osteosarcoma (OS) remain largely unclear. Here, we investigated the expression and function of a novel circular RNA (circRNA), circROCK1-E3/E4, which is back-spliced from exons 3 and 4 of Rho-associated coiled-coil containing protein kinase 1 (ROCK1) in OS. We found that circROCK1-E3/E4, regulated by the well-known RNA-binding protein quaking (QKI), was downregulated in OS and correlated with unfavorable clinical features of patients with OS. Functional proliferation and cell motility assays indicated that circROCK1-E3/E4 serves as a tumor suppressor in OS cells. Mechanistically, circROCK1-E3/E4 suppressed proliferation and migration by upregulating phosphatase and tensin homolog (PTEN) through microRNA-532-5p (miR-532-5p) sponging. In the constructed nude mouse model, circROCK1-E3/E4 inhibited tumor growth and lung metastasis in vivo. This study demonstrates the functions and molecular mechanisms of circROCK1-E3/E4 in the progression of OS. These findings may identify novel targets for the molecular therapy of OS.