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Influence of Carbon Fiber on Corrosion Behavior of Carbon Steel in Simulated Concrete Pore Solutions
( Yuming Tang ),( Yuchao Dun ),( Guodong Zhang ),( Xuhui Zhao ),( Yu Zuo ) 한국부식방식학회(구 한국부식학회) 2017 Corrosion Science and Technology Vol.16 No.4
Galvanic current measurement, polarization curves, electrochemical impedance spectroscopy and weight loss test were used to study the corrosion behavior of carbon steel before and after carbon fibers coupling to the carbon steel in simulated concrete pore solutions, and the film composition on the steel surface was analyzed using XPS method. The results indicate that passive film on steel surface had excellent protective property in pore solutions with different pH values (13.3, 12.5 and 11.6). After coupling with carbon fibers the area ratio of carbon steel to carbon fiber was 12.31), charge transfer resistance Rct of the steel surface decreased and the Fe3+/Fe2+ value in passive film decreased. As a result, stability of the film decreased and the corrosion rate of steel increased. Decreasing of the area ratio of steel to carbon fiber from 12.3 to 6.15 resulted in the decrease in Rct and the increase in corrosion rate. Especially in the pore solution with pH 11.6, the coupling leads the carbon steel to corrode easily.
Chen, Yuchao,Tang, Haoyue,Wang, Jintao,Yang, Pengkun,Tassiulas, Leandros 한국통신학회 2023 Journal of communications and networks Vol.25 No.5
In this paper, we consider sampling an Ornstein-Uhlenbeck (OU) process through a channel for remote estimation. The goal is to minimize the mean square error (MSE) at the estimator under a sampling frequency constraint when the channel delay statistics is unknown. Sampling for MSE minimization is reformulated into an optimal stopping problem. By revisiting the threshold structure of the optimal stopping policy when the delay statistics is known, we propose an online sampling algorithm to learn the optimum threshold using stochastic approximation algorithm and the virtual queue method. We prove that with probability 1, the MSE of the proposed online algorithm converges to the minimum MSE that is achieved when the channel delay statistics is known. The cumulative MSE gap of our proposed algorithm compared with the minimum MSE up to the $(k+1)$-th sample grows with rate at most $\mathcal{O}(\ln k)$. Our proposed online algorithm can satisfy the sampling frequency constraint theoretically. Finally, simulation results are provided to demonstrate the performance of the proposed algorithm.
Hongxiang Xue,Yuchao Yuan,Wenyong Tang 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.2
Surge motion of top-end platform induced by periodic wave makes marine flexible riser encounter equivalent sheared-oscillatory flow, under which the Vortex-induced Vibration (VIV) response will be more complicated than pure sheared flow or oscillatory flow cases. Based on a time domain forcedecomposition model, the VIV response characteristics under sheared-oscillatory flows are investigated numerically in this paper. Firstly, the adopted numerical model is validated well against laboratory experiments under sheared flow and oscillatory flow. Then, 20 sheared-oscillatory flow cases with different oscillation periods and top maximum current velocities are designed and simulated. Under long and short oscillation period cases, the structural response presents several similar features owing to the instantaneous sheared flow profile at each moment, but it also has some different patterns because of the differently varying flow field. Finally, the effects and essential mechanism of oscillation period and top maximum current velocity on VIV response are discussed systematically.
Xue, Hongxiang,Yuan, Yuchao,Tang, Wenyong The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.2
Surge motion of top-end platform induced by periodic wave makes marine flexible riser encounter equivalent sheared-oscillatory flow, under which the Vortex-induced Vibration (VIV) response will be more complicated than pure sheared flow or oscillatory flow cases. Based on a time domain force-decomposition model, the VIV response characteristics under sheared-oscillatory flows are investigated numerically in this paper. Firstly, the adopted numerical model is validated well against laboratory experiments under sheared flow and oscillatory flow. Then, 20 sheared-oscillatory flow cases with different oscillation periods and top maximum current velocities are designed and simulated. Under long and short oscillation period cases, the structural response presents several similar features owing to the instantaneous sheared flow profile at each moment, but it also has some different patterns because of the differently varying flow field. Finally, the effects and essential mechanism of oscillation period and top maximum current velocity on VIV response are discussed systematically.
Lehua Cheng,Dongrui Yu,Enzhu Hu,Yuchao Tang,Kunhong Hu,Karl David Dearn,Xianguo Hu,Min Wang 한국탄소학회 2018 Carbon Letters Vol.26 No.-
An electroless deposition method was used to modify the surface properties of rice husk ceramic particles (RHC) by depositing nano-nickel on the surface of the RHC (Ni-RHC). The dry tribological performances of aluminum matrix composite adobes containing different contents of RHC and Ni-RHC particles have been investigated using a micro-tribometer. Results showed that the Ni–RHC particles substantially improved both the friction and wear properties of the Ni-RHC/aluminum matrix adobes. The optimal concentration was determined to be 15 wt% for both the RHC and Ni–RHC particles. The improvements in the tribological properties of aluminum adobes including the Ni-RHC were ascribed to frictioninduced peeling off of Ni coating and formation of protection layer on the wear zone, both of which led to low friction and wear volume.
Zhaoyi Li,Liang Sun,Zhongjun Fu,Yuchao Li,Zhaohui Jiang,Bingtao Tang,Quan Ji,Yanzhi Xia,Ming Wang,Haofei Huang 한국섬유공학회 2021 Fibers and polymers Vol.22 No.3
Calcium alginate fiber is a biomaterial with promising application in textile industry. However, the poor dyeingproperty of this fiber restricts its development. In this study, three PVAm (polyvinylamine) dyes were applied to the exhaustdyeing of calcium alginate fiber and their dyeing behavior under different dyeing conditions was studied. The dyeing resultsrevealed that PVAm dyes were firmly adsorbed on calcium alginate fiber by coordination bonding formed between theprimary amino groups in PVAm backbones of dyes and Ca2+ ions in calcium alginate fiber. This special complex dyeingmode was further confirmed by a Langmuir-type adsorption manner of PVAm-1 dye for calcium alginate fiber. By theformation of this stable chelation structure between dyes and fibers, high exhaustion rates (88.9-97.1 %) and excellent colorfastness were obtained. SEM and XRD results also showed that the surface and crystal phase of dyed fibers had very slightchanges compared to those of original calcium alginate fibers. The strength property of the fiber was also maintained wellafter this special complex dyeing process.