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- 저자 : Xingyu Xu (검색결과 6 건)
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Effects of Secondary Elements on Vortex-Induced Vibration of a Streamlined Box Girder
Xingyu Chen,Fang Qiu,Haojun Tang,Yongle Li,Xinyu Xu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.1
Box girders are aerodynamically favorable, and the paper presents a study on the vortex-induced vibration (VIV) of this girder type at large angles of attack. Taking a box girder as an example, the form of the guardrails and the position of the maintenance tracks were improved to increase the VIV performance. The aerodynamic mechanism was further investigated according to the change in flow field around the girder. Results showed that the VIV performance of the box girder at positive angles of attack is worse. Improving secondary elements is an effective way to increase the VIV performance. Adding four rectangle bars above the original guardrails could achieve the target by preventing the generation of the vortex and blocking its movement. Moving the maintenance tracks inwards with a reasonable distance could also achieve the target as the flow passes through the girder more smoothly. With the combination of the optimal form of the guardrails and the optimal position of the maintenance tracks, the VIV performance of the bridge is higher. The countermeasures provide reference for the inhibition of the VIV of box girders.
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Xinyu Xu,Yingliang Wang,Xingyu Chen,Xiaolong Zheng,Yongping Zeng 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4
In order to study the vortex-induced vibration (VIV) characteristics and equivalent static force calculation method of circular steel hangers on the arch bridge, a numerical simulation model of VIV was established using FLUENT software, and the reliability of the model was verified by wind tunnel tests. Effects of wind speed, damping ratio, initial tension and slenderness ratio on the VIV characteristics of circular steel hanger were investigated. Furthermore, the equivalent static force calculation formula and loading range of hanger considering VIV were presented. The results show that with the hanger’s damping ratio decreasing, the maximum amplitude and the lock-in wind speed range increases gradually, while the wind speed and frequency of VIV at the maximum amplitude were not significantly affected. As the initial tension increases or the slenderness ratio decreases, the frequency of VIV increases, and the wind speed corresponding to the maximum amplitude increases, however the maximum vibration amplitude has few changes. Based on a number of numerical analyses on VIV characteristics of hangers, the equivalent static force calculation method is put forward. The equivalent static force calculation method could provide a reference for the design and static analysis of the circular steel hangers.
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Yuexuan Xu,Xin Guo,Bokai Xuan,Hao Sun,Gaowei Zhang,Jian Li,Xingyu Huo,Zhifeng Gu 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.3
This paper investigates an impedance-based iterative learning sliding mode control scheme for robotassisted bathing, taking into consideration scenarios with unknown model parameters. Initially, the utilization ofimpedance control is not confined to merely adjusting the desired trajectory but is also instrumental in ensuringactive compliance control during the robot-assisted bathing procedure. Furthermore, an iterative learning control(ILC) is devised to estimate the iteration-invariant dynamic parameters, which are intricate and challenging to precisely ascertain in practical applications. To mitigate the effect of divergent initial conditions in ILC, a trajectoryreconstruction method is introduced, thus ensuring the convergence of tracking errors even when starting from random initial states. Moreover, an adaptive sliding mode control mechanism is proposed to counteract non-parametricexternal disturbances and the torque generated through human-machine interaction during the bathing process. Theconvergence of the double closed-loop system in both the time and iterative domains is demonstrated through theapplication of the composite energy function method. Eventually, the efficacy and superiority of the control strategyoutlined in this paper are jointly verified through co-simulation employing MATLAB and ADAMS.
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Pan, Shifeng,Chen, Yongfang,Zhang, Lin,Liu, Zhuang,Xu, Xingyu,Xing, Hua Asian Australasian Association of Animal Productio 2022 Animal Bioscience Vol.35 No.5
Objective: Excessive lipid accumulation in adipocytes results in prevalence of obesity and metabolic syndrome. Curcumin (CUR), a naturally phenolic active ingredient, has been shown to have lipid-lowering effects. However, its underlying mechanisms have remained largely unknown. Therefore, the study aims to determine the effect of CUR on cellular lipid accumulation in porcine subcutaneous preadipocytes (PSPA) and to clarify novel mechanisms. Methods: The PSPA were cultured and treated with or without CUR. Both cell counting Kit-8 and lactate dehydrogenase release assays were used to examine cytotoxicity. Intracellular lipid contents were measured by oil-red-o staining extraction and triglyceride quantification. Apoptosis was determined by flow cytometry and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labelling assay. Adipogenic and apoptosis genes were analyzed by quantitative polymerase chain reaction and Western blot. Results: The CUR dose-dependently reduced the proliferation and lipid accumulation of PSPA. Noncytotoxic doses of CUR (10 to 20 μM) significantly inhibited extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and expression of adipogenic genes peroxisome proliferation-activity receptor-γ (PPAR-γ), CCAAT/enhancer binding protein-α, sterol regulatory element-binding protein-1c, adipocyte protein-2, glucose transporter-4 as well as key lipogenic enzymes fatty acid synthase and acetyl-CoA carboxylase, while ERK1/2 activation significantly reversed CUR-reduced lipid accumulation by increasing PPAR-γ. Furthermore, compared with differentiation induced media treated cells, higher dose of CUR (30 μM) significantly decreased the expression of AKT and B-cell lymphoma-2 (BCL-2), while increased the expression of BCL-2-associated X (BAX) and the BAX/BCL-2 expression ratio, suggesting triggered apoptosis by inactivating AKT and increasing BAX/BCL-2 ratio and Caspase-3 expression. Moreover, AKT activation significantly rescued CUR inhibiting lipid accumulation via repressing apoptosis. Conclusion: These results demonstrate that CUR is capable of suppressing differentiation by inhibiting ERK1/2-PPAR-γ signaling pathway and triggering apoptosis via decreasing AKT and subsequently increasing BAX/BCL-2 ratio and Caspase-3, suggesting that CUR provides an important method for the reduction of porcine body fat, as well as the prevention and treatment of human obesity.
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