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Fangfang Geng,Youliang Ding,Hongen Xie,Jianyong Song,Wanheng Li 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.1
A three-dimensional finite element model for the Jiashao Bridge, the longest multi-span cablestayed bridge in the world, is established using the commercial software package ANSYS. Dynamic characteristics of the bridge are analyzed and the effects of structural system measures including the rigid hinge, auxiliary piers and longitudinal constraints between the girders and side towers on the dynamic properties including modal frequency, mode shape and effective mass are studied by referring to the Jiashao Bridge. The analysis results reveal that: (i) the installation of the rigid hinge significantly reduces the modal frequency of the first symmetric lateral bending mode of bridge deck. Moreover, the rigid hinge significantly changes the mode shape and effective mass of the first symmetric torsional mode of bridge deck; (ii) the layout of the auxiliary piers in the side-spans has a limited effect on changing the modal frequencies, mode shapes and effective masses of global vibration modes; (iii) the employment of the longitudinal constraints significantly increases the modal frequencies of the vertical bending modes and lateral bending modes of bridge deck and have significant effects on changing the mode shapes of vertical bending modes and lateral bending modes of bridge deck. Moreover, the effective mass of the first anti-symmetric vertical bending of bridge deck in the longitudinal direction of the fully floating system is significantly larger than that of the partially constrained system and fully constrained system. The results obtained indicate that the structural system measures of the multi-span cable-stayed bridge have a great effect on the dynamic properties, which deserves special attention for seismic design and wind-resistant design of the multi-span cable-stayed bridge.
Fangfang Jie,Mingjia Liao,Siwei Jiang,Chunyu Song,Chengli Tang,Boshui Chen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12
Phosphonation and nitrogenation of methyl epoxyoleate (MEO) were done to prepare phosphonitrogenated methyl epoxyoleate (PNMEO). The structural characteristics of PNMEO were characterized. The tribological properties of PNMEO and MEO as additives in a paraffin oil and a rapeseed oil were evaluated, and the morphologies, element compositions and tribochemical species of worn surfaces were analyzed. Results showed that PNMEO was more efficient in enhancing tribological properties of oils than MEO. Results also showed that PNMEO and MEO were more powerful in paraffin oil than in rapeseed oil in improving loadcarrying, friction-reducing and anti-wear performances, but in rapeseed oil than in paraffin oil in improving extreme pressure property. The tribological mechanisms of PNMEO in reducing friction and wear were attributed to PNMEO-involved tribo-adsorptions and tribo-reactions to produce a composite boundary lubrication film which consisted of a matrix of PNMEO with inclusions of iron oxide, polyphosphates, aminic compounds, and the base oil molecules.
Design and Implementation of the Phase-locked Amplifier
Mingxin Song,Fangfang Liu 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.5
The phase-locked amplifier with output stability can filter out the noise effectively and the weak signal will be extracted from the noise and be amplified. The signal processing is relatively simple, so it is an effective way to detect the weak signal. It uses the phase sensitive detector (Phase Sensitive Detection, PSD) technique to identify the test signal, which has same frequency with the reference signal, and eliminate the interference noise signal of different frequency, so as to accurately measure the size of the measured signal. In this paper, switching correlator is taken as a core part of lock-in amplifier with large dynamic range, strong anti-overload and no non-linear problems. Moreover, lock-in amplifier output signal amplitude has no impact from the amplitude of the reference .
Geng, Fangfang,Ding, Youliang,Xie, Hongen,Song, Jianyong,Li, Wanheng Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.1
A three-dimensional finite element model for the Jiashao Bridge, the longest multi-span cable-stayed bridge in the world, is established using the commercial software package ANSYS. Dynamic characteristics of the bridge are analyzed and the effects of structural system measures including the rigid hinge, auxiliary piers and longitudinal constraints between the girders and side towers on the dynamic properties including modal frequency, mode shape and effective mass are studied by referring to the Jiashao Bridge. The analysis results reveal that: (i) the installation of the rigid hinge significantly reduces the modal frequency of the first symmetric lateral bending mode of bridge deck. Moreover, the rigid hinge significantly changes the mode shape and effective mass of the first symmetric torsional mode of bridge deck; (ii) the layout of the auxiliary piers in the side-spans has a limited effect on changing the modal frequencies, mode shapes and effective masses of global vibration modes; (iii) the employment of the longitudinal constraints significantly increases the modal frequencies of the vertical bending modes and lateral bending modes of bridge deck and have significant effects on changing the mode shapes of vertical bending modes and lateral bending modes of bridge deck. Moreover, the effective mass of the first anti-symmetric vertical bending of bridge deck in the longitudinal direction of the fully floating system is significantly larger than that of the partially constrained system and fully constrained system. The results obtained indicate that the structural system measures of the multi-span cable-stayed bridge have a great effect on the dynamic properties, which deserves special attention for seismic design and wind-resistant design of the multi-span cable-stayed bridge.
Liu Ying,Li Bing,Song FangFang,Gao HanYu,Huang LiangDong,Chen XuXuan 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6
High quality power is the prerequisite for high precision measurement of an electronic voltage transformer. In order to ensure a compact structure and stable operation of the transformer, this paper proposes a circuit and high voltage energy harvest of high precision electronic voltage transformer based on coupling capacitance. The energy extraction circuit is directly connected with the high voltage terminal through a capacitor, and the low DC voltage is obtained through the diode rectifier bridge. A self-holding duty cycle regulating circuit is installed on the DC side, and the power required by the load can be automatically adjusted to match the load. Because the overall load of the power extraction circuit is capacitive, there is no ferro-resonance problem. Furthermore, there is also no MCU in the device, so that the whole circuit has the advantages of small power loss, small volume, strong anti-interference ability, and can provide a stable DC power for the metering device. The proposed method is verifi ed in simulations using PSCAD/EMTDC.
An architecture of lifecycle fatigue management of steel bridges driven by Digital Twin
Jiang, Fei,Ding, Youliang,Song, Yongsheng,Geng, Fangfang,Wang, Zhiwen Techno-Press 2021 Structural monitoring and maintenance Vol.8 No.2
The fatigue of steel bridges poses a great threat to their safety and functionality. However, current approaches for fatigue management are largely based on heuristic design philosophies, physical testing, and bridge managers' experience. This paper proposes a closed lifecycle fatigue management driven by Digital Twin for steel bridges. To provide clarity around the concept, the definition of Digital Twin for steel bridges is given at first. Then eight functional modules supporting Digital Twin are outlined in detail, aiming to provide a reference for the future development of Digital Twin in fatigue management. Finally, the implementation mechanism of Digital Twin is further described over different phases during the bridge lifecycle. This paper also identifies two main obstacles for the development of Digital Twin: i) the lack of understanding of steel bridge fatigue, and ii) the insufficiency of the present technologies.
Hongfei Zhu,Congcong Liu,Haijun Song,Jingkun Xu,Fangfang Kong,Jianmin Wang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
Poly(3-hexylthiophene) (P3HT) films doped with iodine vapor have been prepared by casting a P3HT solution on glass substrates and their thermoelectric (TE) performances has been investigated. The maximum Seebeck coefficient and electrical conductivity of iodine-doped P3HT films were 386 μV·K−1 (at room temperature) and 4.7 × 10−1 S·cm−1, which is about five orders of magnitude higher than that of pristine P3HT films. The power factor of these iodine-doped P3HT films was estimated to be 7.0 μW·m−1·K−2 at room temperature, which is a relative high value for organic TE materials. The UV-vis spectra of iodine-doped P3HT films showed a slight red shift of the iodine-doped P3HT compared to those of pristine P3HT films. Atomic force microscopy images indicated the conformational changes in P3HT chains after treatment with iodine vapor. During this treatment, the P3HT chains self-organized into a more ordered structure, this organization improved the charge carrier transport capability and the TE performance of P3HT the films.