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- 저자 : Rongfeng Chen (검색결과 3 건)
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Meiling Zhuang,Changqing Miao,Rongfeng Chen 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.6
A fatigue design method for the orthotropic steel deck bridges is proposed. The stress characteristics of welded details are analyzed using the finite element method. Based on the fatigue performance, the structural parameters of the orthotropic steel decks (OSDs) are optimized using the combination BP (back propagation) neural network and genetic algorithms (GA). The calculated results demonstrate that the weld stresses at the deck plate-to-rib, deck plate-to-rib-to-diaphragm welded details are mainly bending stress while those at the rib-to-rib welded details are mainly membrane stress. The fatigue stress of each weld is deeply affected by the transverse and longitudinal direction positions. The local effect of stress distribution of all welded details is remarkable. The calculated results obtained using the proposed model are in good agreement with those obtained using ANSYS and the errors are within 5%. The optimal structural results are highly influenced by the applied wheel loadings, while the optimal results for the deck thickness and the U-rib opening size are highly influenced by temperature. Especially on the ordinary lane, temperature has a great effect on the fatigue performance for all welded details.
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Improved Model Predictive Control for H-bridge Cascaded STATCOM
Xu Rong,Yu Yong,Wu Jian,Yang Rongfeng,Xu Dianguo,Chen He,Yu Yannan,Ni Ronggang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. In order to improve the performance of STATCOM, an improved model predictive control (MPC) method is put forward in this paper. In the proposed MPC, the difference equations which are derived from the transfer functions of controlling variables and controlled variables in STATCOM are used as the predictive control model, the error between the output of STATCOM and predictive model is used to design feedback correction controller and rolling optimization controller. Meanwhile, the introduced repetitive controller is used to eliminate the inherent steady error. The actual H-bridge cascaded STATCOM is constructed and a series of verification tests are executed. The experimental results prove that the output voltage and current of H-bridge cascaded STATCOM with the proposed MPC have smaller distortion and better sinusoidal shape than those of the traditional Proportion Integral (PI) control. Moreover, the performance of H-bridge cascaded STATCOM is great in high power experiment.
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Deng Tingyu,Fang Bijun,Zhu Rongfeng,Chen Jianwei,Luo Haosu 한국물리학회 2021 Current Applied Physics Vol.21 No.-
Due to the good dielectric, piezoelectric and ferroelectric properties, the pseudo-ternary ferroelectric single crystals Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) have been widely concerned and studied. In this study we found that the dynamic hysteresis loop area <A> with electric field E0 and frequency f0 of the 0.16 Pb(In1/2Nb1/2)O3-0.62 Pb(Mg1/3Nb2/3)O3-0.22PbTiO3 (0.16PIN-0.62PMN-0.22 PT) single crystals satisfies the relational equation <A> ∝ E0β f0α . In the <A> ∝ E0β relationship, both linear stages are found correlated with the low electric field in the first stage E0<Ec and the high electric field in the third stage E0 > 3Ec. The hysteresis loop area <A> with frequency f0 relationship satisfies the equation <A> ∝ f0α with roughly linear trend and the hysteresis loop area <A> decreases with increasing frequency f0. Such electric field dependent dynamic hysteresis scaling can be observed by polarized light microscopy.
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