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Sun, Feifei,Duan, Ningling,Wang, Meng,Yang, Jiaqi Council on Tall Building and Urban Habitat Korea 2021 International journal of high-rise buildings Vol.10 No.3
Dynamic characteristics of tall building structures with double negative stiffness damped outriggers (2NSDO) are parametrically studied using the theoretical formula. Compared with one negative stiffness damped outrigger (1NSDO), 2NSDO can achieve a similar maximal modal damping ratio with a smaller negative stiffness ratio. Besides, the 2NSDO can improve the maximum achievable damping ratio to about 30% with less consumption of an outrigger damping coefficient compared with the double conventional damped outriggers (2CDO). Besides, the responses of structures with 2NSDO under fluctuating wind load are investigated by time-history analysis. Numerical results show that the 2NSDO is effective in reducing structural acceleration under fluctuating wind load, being more efficient than 1NSDO.
Study on electromechanical performance of steering of the electric articulated tracked vehicles
Jiaqi Wu,Guoqiang Wang,Huanyu Zhao,Kangkang Sun 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
Articulated tracked vehicles (ATVs) usually use hydraulic drive or mechanical drive modes. Electrically driven tracked vehicles have become a promising development direction for saving energy and meeting the environment requirements. In this study, based on the mechanical motion equation and the dynamic ATV equation, the electromechanical coupling model of the track vehicles is established by coupling the motor equation. The typical mechanical and electrical parameters in the ATV steering process are measured and compared with the numerical results to verify the correctness of the electromechanical coupling model. Experimental results indicate the main mechanical and electrical parameters of the ATV electro-mechanical system are changed at different articulated point deflection angles. The characteristic parameters of ATV include the change in current and voltage, the size of trajectory radius and the change of power under different deflection angles (10°, 15°, 20°, 25° and 30°), all of which are of great significance for the control of ATV. The current and voltage signals of ATV under specific trajectory can be calculated in reverse by the model, thereby providing a theoretical basis for the trajectory control of articulated vehicles. Therefore, this study provides a reference for the theoretical analysis of electromechanical performance, road driving performance and vehicle design of the electric ATV.
POWER LOSS EVALUATION OF AUTOMATED MANUAL TRANSMISSION WITH GEARSHIFT ASSISTANT MECHANISM
Zhiqiang Sun,Bingzhao Gao,Jiaqi Jin,Kazushi Sanada 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2
This paper deals with the power loss evaluation in gearshift assistant mechanism applied in automated manual transmission. The originalities include building the numerical models of gearshift assistant mechanism efficiency analysis for cost penalty evaluation and designing gear ratio matching algorithm to match the gear ratios of epicyclic mechanism with desired ones, which is expected to minimize the clutch friction losses by reducing the angular velocity differences between two clutch pads. In the numerical models, gear meshing losses and friction losses are considered the main power sink. By the kinematic relationships and power flow analysis, a set of generalized efficiency calculating formulas of simple epicyclic mechanism in six working modes with respect to teeth numbers are summarized, which are useful computer-aided tools in calculating multiple simple epicyclic mechanisms’ efficiency. The matched gear ratios and the efficiency models are tested on a powertrain simulation model and several simulation results are reported. Finally, this paper summarized the merits and further research targets of the proposed transmission, which is a promising structure to achieve swift and smooth gearshift with low power losses.
( Xiongshan Sun ),( Weiwei Zhao ),( Qiang Wang ),( Jiaqi Zhao ),( Dachun Yang ),( Yongjian Yang ) 생화학분자생물학회 2022 BMB Reports Vol.55 No.5
Characterized by abnormal proliferation and migration of vascular smooth muscle cells (VSMCs), neointima hyperplasia is a hallmark of vascular restenosis after percutaneous vascular interventions. Vaccinia-related kinase 1 (VRK1) is a stress adaption-associated ser/thr protein kinase that can induce the proliferation of various types of cells. However, the role of VRK1 in the proliferation and migration of VSMCs and neointima hyperplasia after vascular injury remains unknown. We observed increased expression of VRK1 in VSMCs subjected to platelet-derived growth factor (PDGF)-BB by western blotting. Silencing VRK1 by shVrk1 reduced the number of Ki-67-positive VSMCs and attenuated the migration of VSMCs. Mechanistically, we found that relative expression levels of β-catenin and effectors of mTOR complex 1 (mTORC1) such as phospho (p)-mammalian target of rapamycin (mTOR), p-S6, and p-4EBP1 were decreased after silencing VRK1. Restoration of β-catenin expression by SKL2001 and re-activation of mTORC1 by Tuberous sclerosis 1 siRNA (siTsc1) both abolished shVrk1-mediated inhibitory effect on VSMC proliferation and migration. siTsc1 also rescued the reduced expression of β-catenin caused by VRK1 inhibition. Furthermore, mTORC1 re-activation failed to recover the attenuated proliferation and migration of VSMC resulting from shVrk1 after silencing β-catenin. We also found that the vascular expression of VRK1 was increased after injury. VRK1 inactivation in vivo inhibited vascular injury-induced neointima hyperplasia in a β-catenin-dependent manner. These results demonstrate that inhibition of VRK1 can suppress the proliferation and migration of VSMC and neointima hyperplasia after vascular injury via mTORC1/β-catenin pathway. [BMB Reports 2022; 55(5): 244-249]