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- 저자 : Chaoran Li (검색결과 5 건)
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Transparent Fluorinated Poly(imide siloxane) Copolymers with Good Adhesivity
Linshuang Li,Yong Xu,Jianfei Che,Xu Su,Chaoran Song,Xiuping Ma 한국고분자학회 2017 Macromolecular Research Vol.25 No.11
A series of fluorinated poly(imide siloxane) (PIS) copolymers were prepared with fluorine dianhydride 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and two kinds of functional diamine, 2,2'-bis(trifluoromethyl)-[ 1,1'-biphenyl]-4,4'-diamine (TFMB) and 1,3-bis(3-aminopropyl) tetramethyldisiloxane (GAPD) via a conventional two-stage process with thermal imidization. The soft and hard segments in the copolymer chain were composed of 6FDA-GAPD and 6FDA-TFMB, respectively. The structure of the resulting copolymers was determined by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. Optical, adhesion, mechanical, and thermal properties of these PIS copolymers have been evaluated with respect to real siloxane loading kept to 0, 1.4, 2.6, 4.1, and 5.5wt% in the copolymers, which is lower than the theoretical content of siloxane loading due to a disproportionation reaction of the siloxane chain. The resulting PIS copolymers showed excellent optical transparency in the UV-visible range and good adhesion property. The cutoff absorption wavelength (λ0) of the resulting PIS copolymers films was less than 345 nm and the maximum transmittance (λmax) was up to 91%. The introduction of siloxane segment dramatically improved the adhesion property of PIS copolymers from 1.29 to 2.26MPa (measured by means of shear strength) compared to the fluorinated homopolyimide (6FDA-TFMB) synthesized without siloxane moiety. The thermal and mechanical properties of the resulting PIS copolymers decreased slightly with the increase in siloxane loading but still remain a good level. Due to the addition of trifluoromethyl (-CF3) group and siloxane moiety, the solubility of PIS films was greatly enhanced and they were able to be dissolved in polar aprotic solvents, such as DMAC, DMF, and NMP. The contact angle, surface energy and water absorption were also studied in order to discuss their hydrophobic property.
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A Patent Pool Partner Selection Method Based on Time Degrees and Intuitionistic Fuzzy Entropy
Chen Wei,Li Jinqiu,Lin Chaoran,Yang Zaoli 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.7
Patent pool partner selection is a typical multi-attribute decision making (MADM) problem, and that based on intuitionistic fuzzy (IF) theory is widely applied in this research field. In this paper, a dynamic MADM method based on time degrees and intuitionistic fuzzy entropy (IFE) is proposed. We determine the attribute weights under different time sequence based on IFE; and establish a non-linear programming model combining the principle of time degrees with grey entropy theory to calculate time weights vector; the dynamic intuitionistic fuzzy weighted geometric-operator(DIFWG) is used to aggregate different periods of weighted intuitionistic fuzzy decision-making matrix; TOPSIS was integrated into dynamic intuitionistic fuzzy multiple attribute decision making (DIF-MADM), by calculating the relative closeness of alternatives with ideal solution, we obtain the optimum alternative; finally, an example is given to illustrate the applicability and rationality of the proposed approach.
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A Three-Stage Dynamic Risk Model for Metro Shield Tunnel Construction
Na Xu,Chaoran Guo,Li Wang,Xueqing Zhou,Ying Xie 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2
The complex construction process of the metro shield method often leads to safety accidents. The various construction stages of shield tunnel construction comprise different construction activities and are accompanied by different safety risk factors. However, traditional risk assessment often evaluates the risk factors as a whole before shield tunnel construction and does not evaluate the risk factors dynamically by construction stages and by construction activities. To fill this gap, this paper aims to construct a dynamic Bayesian-based safety risk assessment model for shield tunnel construction from the perspective of changing construction stages and activities. First, safety risk factors were identified using the work breakdown structure-risk breakdown structure (WBS-RBS) method. Then, a three-stage dynamic assessment model of safety risks was constructed to depict the shield launch, shield tunnel, and shield reach. The dynamic Bayesian network (DBN) was improved to address the model with triangular fuzzy numbers and the leaky noisy-or-gate extension model. Finally, a case study was conducted. The model proposed in this paper is able to reveal the dynamic evolution of safety risks triggered by different construction activities. It offers a new simulated model for the prevention of safety accidents in the construction of metro shields.
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Optimization of maximum torque output in the wide speed range of a PMSM traction control system
Zhang, Weiwei,Xiao, Fei,Liu, Jilong,Mai, Zhiqin,Li, Chaoran The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1
This paper introduces a permanent magnet synchronous motor maximum torque control method for the wide speed range of a traction control system. This method tracks the maximum torque per ampere operating point and generates a d-axis current command according to the injection of a high-frequency angle signal to the current. This method is parameter independent when looking for the maximum torque per ampere operating point. By not injecting any real signal to a permanent magnet synchronous motor, this method does not increase the amount of copper and iron losses resulting from real signal injection. To obtain a maximum torque output in a wide speed range, this method considers the maximum amplitude limits of voltage and current when the traction motor runs in a flux weakening control field. This method is also robust to current and voltage harmonics, speed mutations, and torque disturbances. Experiment and analysis are conducted on a permanent magnet synchronous motor traction control system prototype under various operating conditions to verify the effectiveness of this method.
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Weiwei Zhang,Fei Xiao,Jilong Liu,Zhiqin Mai,Chaoran Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4
Rail transportation interior permanent magnet synchronous motor traction control system (IPMSM TCS) requires high torque output capability. Traditional algorithms used to fnd the maximum torque per ampere (MTPA) operating point in TCS have strong dependence on motor parameters. Because the algorithm is less robust to motor parameters, there will be deviation between the MTPA operating point and the actual value when the parameters change, so that it is difcult to guarantee the torque output capability of the traction system under diferent working conditions. This paper introduces a current angle signal injection control method (CASIM) to solve this problem. The proposed method tracks the MTPA operating point and generates d-axis current command according injecting an angle signal to current and making the partial derivative of torque to current angle equal to zero. At the same time, less motor parameters are needed to calculate the torque in this method. Consequently, in the process of looking for MTPA operating point, the accuracy is less afected by the variation of motor parameters. And also it does not inject any real signal to IPMSM, so that it does not increase copper and iron losses. Moreover, it is robust to speed mutation and torque disturbances. The efectiveness of CASIM proposed in this paper is proved by simulation and experiment results on an IPMSM TCS platform.
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