Design, fabrication and test of a taper-type half-wave superconducting cavity with the optimal beta of 0.15 at IMP

Yue Weiming,Zhang Shengxue,Li Chunlong,Jiang Tiancai,Liu Lubei,Wang Ruoxu,Huang Yulu,Tan Teng,Guo Hao,Zaplatin Evgeny,Xiong Pingran,Wu Andong,Wang Fengfeng,Zhang Shenghu,Huang Shichun,He Yuan,Yao Zeen 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8

As a part of R&D work for the high intensity proton linac of China Accelerator Driven Sub-critical System project, a superconducting half-wave cavity with a frequency of 162.5 MHz and an optimal beta of 0.15 (HWR015) has been developed at Institute of Modern Physics (IMP), Chinese Academy of Sciences. In this paper, the design and test results will be described in detail. We introduced a new stiffening strategy for the HWR cavity, the simulation results show that the cavity has much lower frequency sensitivity coefficient (df/dp), Lorentz force detuning coefficient (KL), and can achieve more stable mechanical properties. The performance of the HWR cavity operated in cryostat will be also reported.

MicroRNA-455-3p promotes TGF-β signaling and inhibits osteoarthritis development by directly targeting PAK2

Shu Hu,Xiaoyi Zhao,Guping Mao,Ziji Zhang,Xingzhao Wen,Chengyun Zhang,Weiming Liao,Zhiqi Zhang 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

MicroRNAs (miRNAs, miR) play a key role in the pathogenesis of osteoarthritis (OA). Few studies have examined theregulatory role of P21-activated kinases (PAKs), a family of serine/threonine kinases, in OA. The aim of this study was todetermine whether miR-455-3p can regulate cartilage degeneration in OA by targeting PAK2. MiR-455-3p knockoutmice showed significant degeneration of the knee cartilage. MiR-455-3p expression increased and PAK2 expressiondecreased in the late stage of human adipose-derived stem cell (hADSC) chondrogenesis and in chondrocytesaffected by OA. Furthermore, in both miR-455-3p-overexpressing chondrocytes and PAK2-suppressing chondrocytes,cartilage-specific genes were upregulated, and hypertrophy-related genes were downregulated. A luciferase reporterassay confirmed that miR-455-3p regulates PAK2 expression by directly targeting the 3′-untranslated regions (3′UTRs)of PAK2 mRNA. IPA-3, a PAK inhibitor, inhibited cartilage degeneration due to OA. Moreover, suppressing PAK2promoted R-Smad activation in the TGF/Smad signaling pathway in chondrocytes. Altogether, our results suggest thatmiR-455-3p promotes TGF-β/Smad signaling in chondrocytes and inhibits cartilage degeneration by directlysuppressing PAK2. These results thus indicate that miR-455-3p and PAK2 are novel potential therapeutic agents andtargets, respectively, for the treatment of OA.

Trisodium citrate-assisted synthesis of BiOBr nanostructure catalyst for efficient activity under visible light

Weiming Zhou,Yifan Jiang,Shichang Sun,Mingxin Zhang,Ibrahim Lawan,Gerard Franklyn Fernando,Liwei Wang,Zhanhui Yuan 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2

A simple one step wet-chemical method assisted by trisodium citrate was employed in the synthesis of BiOBr applied as a photocatalyst. Photocatalytic activity of the BiOBr was investigated for the degradation of Rhodamine B (RhB) dye under visible light irradiation (>420 nm). The results indicated that trisodium citrate is more favorable to the formation of hierarchical architectures and reduces the particle size of BiOBr photocatalyst. BiOBr with hierarchical architectures exhibiting significantly higher catalytic activity than that with ordinary nanostructure. The significant improvement could be attributed to the high specific surface area (24.14m2·g1), average pore sizes (34.09 nm) and average pore volume (0.24 cm3·g1).

Enzymatic Desymmetrization of 3-(4-Fluorophenyl)glutaric Anhydride through Enantioselective Alcoholysis in Organic Solvents

Weiming Liu,Yi Hu,Yang Zhang,Yan Ma,He Huang 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.3

The enzymatic desymmetrization of 3-(4-fluorophenyl)glutaric anhydride (3-FGA) was investigatedthrough lipase-catalyzed enantioselective alcoholysis inorganic solvents. An immobilized Lipase B from CandidaAntarctica (Novozym 435) was found to be an efficientbiocatalyst for the enantioselective alcoholysis of 3-FGA. Methyl tert-butyl ether (MTBE) and methanol were chosenas the suitable reaction medium and acyl acceptor,respectively. The optimum reaction temperature, molarratio of methanol to 3-FGA and 3-FGA concentration were25oC, 2:1 and 100 mM, respectively. Under these conditions,complete conversion was achieved and methyl (S)-3-(4-fluorophenyl)glutarate ((S)-MFG) was obtained in a moderateee value of 80%. Furthermore, the reaction was performedon a gram scale and the ee value of (S)-MFG was enrichedto 96% after treatment with a toluene/hexane (2/1, v/v)mixture.

Sliding Mode Control based on Disturbance Observer for Magnetic Levitation Positioning Stage

Zhang Shansi,Ma Shuyuan,Wang Weiming 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

Magnetic levitation system with the advantages of non-contact, no friction and no wear can satisfy the requirement of high precision and high speed positioning. In this paper, magnetic levitation positioning stage which mainly consists of planar coil and HALBACH permanent magnet array and its control and driving system are designed. Magnetic levitation system is a highly nonlinear and strongly coupled complex system and its control performance can be influenced by the uncertainty and external disturbance. So exact feedback linearization method is used to realize exact linearization and decoupling, and a strategy of sliding mode control based on disturbance observer is proposed to compensate the uncertainty and external disturbance. Detailed proofs of observer’s convergence property and system stability are derived. Both the simulation and experiment results verify the effectiveness of sliding mode control algorithm based on disturbance observer.

Improved Grid Voltage Control Strategy for Wind Farms with DFIGs Connected to Distribution Networks

Zhang, Xueguang,Pan, Weiming,Liu, Yicheng,Xu, Dianguo The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3

This paper presents an improved grid voltage control strategy for wind farms with doubly-fed induction generators (DFIGs) connected to distribution networks based on an analysis of the operation limits of DFIG systems. A modified reactive power limit calculation method in different operation states is proposed and a reactive power control strategy during grid voltage dips/rises is further discussed. A control strategy for compensating unbalanced grid voltage, based on DFIG systems, by injecting negative sequence current into the grid through the grid side converter (GSC) is proposed. In addition, the negative current limit of the GSC is discussed. The distribution principle of the negative sequence current among the different DFIG systems in a wind farm is also introduced. The validity of the proposed voltage control strategy is demonstrated by Matlab/Simulink simulations. It is shown that the stability of a wind farm and the power grid can be improved with the proposed strategy.

Research on the path-following control of rubber-tire trackless train with bogies

Rang Zhang,Gang Shen,Weiming Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3

Aiming at the light rail train with rubber wheel bogies, a path-following control scheme based on road line recognition was proposed. The path-following performance and dynamics performance of the train were analyzed based on a dynamic model of a train with three car bodies. Acquiring the information of the road line, the "feedforward and feedback" method was used to ensure the train to path-following with better dynamics performance and riding quality by controlling the yaw angle of all the rubber wheelsets of the bogies. The simulation results show that under the effect of the path-following control scheme, the train can maintain good curve passing performance, dynamics performance and riding quality when passing through 15 m small curve radius and 50 m S-shaped curve section, respectively.

Improved Grid Voltage Control Strategy for Wind Farms with DFIGs Connected to Distribution Networks

Xueguang Zhang,Weiming Pan,Yicheng Liu,Dianguo Xu 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3

This paper presents an improved grid voltage control strategy for wind farms with doubly-fed induction generators (DFIGs) connected to distribution networks based on an analysis of the operation limits of DFIG systems. A modified reactive power limit calculation method in different operation states is proposed and a reactive power control strategy during grid voltage dips/rises is further discussed. A control strategy for compensating unbalanced grid voltage, based on DFIG systems, by injecting negative sequence current into the grid through the grid side converter (GSC) is proposed. In addition, the negative current limit of the GSC is discussed. The distribution principle of the negative sequence current among the different DFIG systems in a wind farm is also introduced. The validity of the proposed voltage control strategy is demonstrated by Matlab/Simulink simulations. It is shown that the stability of a wind farm and the power grid can be improved with the proposed strategy.

Theoretical and experimental study on damage detection for beam string structure

Haoxiang He,Weiming Yan,Ailin Zhang 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.12 No.3

Beam string structure (BSS) is introduced as a new type of hybrid prestressed string structures. The composition and mechanics features of BSS are discussed. The main principles of wavelet packet transform (WPT), principal component analysis (PCA) and support vector machine (SVM) have been reviewed. WPT is applied to the structural response signals, and feature vectors are obtained by feature extraction and PCA. The feature vectors are used for training and classification as the inputs of the support vector machine. The method is used to a single one-way arched beam string structure for damage detection. The cable prestress loss and web members damage experiment for a beam string structure is carried through. Different prestressing forces are applied on the cable to simulate cable prestress loss, the prestressing forces are calculated by the frequencies which are solved by Fourier transform or wavelet transform under impulse excitation. Test results verify this method is accurate and convenient. The damage cases of web members on the beam are tested to validate the efficiency of the method presented in this study. Wavelet packet decomposition is applied to the structural response signals under ambient vibration, feature vectors are obtained by feature extraction method. The feature vectors are used for training and classification as the inputs of the support vector machine. The structural damage position and degree can be identified and classified, and the test result is highly accurate especially combined with principle component analysis.

Theoretical and experimental study on damage detection for beam string structure

He, Haoxiang,Yan, Weiming,Zhang, Ailin Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.12 No.3

Beam string structure (BSS) is introduced as a new type of hybrid prestressed string structures. The composition and mechanics features of BSS are discussed. The main principles of wavelet packet transform (WPT), principal component analysis (PCA) and support vector machine (SVM) have been reviewed. WPT is applied to the structural response signals, and feature vectors are obtained by feature extraction and PCA. The feature vectors are used for training and classification as the inputs of the support vector machine. The method is used to a single one-way arched beam string structure for damage detection. The cable prestress loss and web members damage experiment for a beam string structure is carried through. Different prestressing forces are applied on the cable to simulate cable prestress loss, the prestressing forces are calculated by the frequencies which are solved by Fourier transform or wavelet transform under impulse excitation. Test results verify this method is accurate and convenient. The damage cases of web members on the beam are tested to validate the efficiency of the method presented in this study. Wavelet packet decomposition is applied to the structural response signals under ambient vibration, feature vectors are obtained by feature extraction method. The feature vectors are used for training and classification as the inputs of the support vector machine. The structural damage position and degree can be identified and classified, and the test result is highly accurate especially combined with principle component analysis.