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- 저자 : Yuwei Liu (검색결과 16 건)
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Liu Feifei,Li Diancheng,Xin Yuwei,Liu Fang,Li Wenxue,Zhu Jiaan 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.2
Objective: Viscoelasticity is an essential feature of nerves, although little is known about their viscous properties. The discovery of shear wave dispersion (SWD) imaging has presented a new approach for the non-invasive evaluation of tissue viscosity. The present study investigated the feasibility of using SWD imaging to evaluate diabetic neuropathy using the sciatic nerve in a diabetic rat model. Materials and Methods: This study included 11 diabetic rats in the diabetic group and 12 healthy rats in the control group. Bilateral sciatic nerves were evaluated 3 months after treatment with streptozotocin. We measured the nerve cross-sectional area (CSA), nerve stiffness using shear wave elastography (SWE), and nerve viscosity using SWD imaging. The motor nerve conduction velocity (MNCV) was also measured. These four indicators and the histology of the sciatic nerves were then compared between the two groups. The performance of CSA, SWE, and SWD imaging in distinguishing the two groups was assessed using receiver operating characteristic (ROC) analysis. Results: Nerve CSA, stiffness, and viscosity in the diabetic group was significantly higher than those in the control group (all p < 0.05). The results also revealed a significantly lower MNCV in the diabetic group (p = 0.005). Additionally, the density of myelinated fibers was significantly lower in the diabetic group (p = 0.004). The average thickness of the myelin sheath was also lower in the diabetic group (p = 0.012). The area under the ROC curve for distinguishing the diabetic neuropathy group from the control group was 0.876 for SWD imaging, which was significantly greater than 0.677 for CSA (p = 0.030) and 0.705 for SWE (p = 0.035). Conclusion: Sciatic nerve viscosity measured using SWD imaging was significantly higher in diabetic rats. The viscosity measured using SWD imaging performed well in distinguishing the diabetic neuropathy group from the control group. Therefore, SWD imaging may be a promising method for the evaluation of diabetic neuropathy.
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Yuwei Liu,Guipeng Chen,Liping Mo,Xinlin Qing 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Thanks to the favorable advantage of reduced magnetic components, single-inductor multi-output DC-DC converters are attractive in low-cost industrial applications. However, when the converters work in continuous conduction mode (CCM), a severe dynamic cross-regulation problem will occur due to the current multiplex of the same inductor. To solve this problem, an improved single-inputdual-output (SIDO) buck converter is proposed in this paper, which employs one coupled inductor with 1:1 turns ratio as a substitution for the inductor. In the proposed converter, the two output voltages can be controlled independently while the advantage of fewer magnetic cores is retained. Moreover, reduced number of semiconductor components is achieved, leading to a lower cost. Besides, because of the 1:1 turns ratio, the magnetizing current is also effectively decreased to the one output current rather than the sum of two output currents, which will reduce the volume of magnetic core.
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Liu Yuwei,Gu Yizhuo,Wang Shaokai,Li Min 한국탄소학회 2023 Carbon Letters Vol.33 No.3
Surface free energy is an important parameter in surface and interface properties of fiber reinforced polymer composite. The BET (Brunauer, Emmett, and Teller) surface area and surface energy of the sample can be obtained by Inverse Gas Chromatography (IGC) based on the adsorption principle. In this paper, surface energy of carbon fiber bundle was tested by means of IGC under different conditions to find reliable test parameters. The main parameters involved include length, mass, and packing density of sample, target fractional surface coverage, flow rate, and maximum elution time. It is demonstrated that IGC has the advantages of simple sample preparation, stable test data, high automation, and high sensitivity for carbon fiber. Among all test conditions, packing density and flow rate have the greatest influences on the experimental results. The optimized test parameters are suitable for various kinds of carbon fiber bundles, including polyacrylonitrile-based and pitch-based carbon fibers with different tensile properties and tow sizes. Moreover, IGC can acutely characterize the surface properties of carbon fibers after carbon nanotube modification and heat treatment, which are hard to carry out using contact angle method.
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Yuwei Sun,Jiaomin Liu,Yonggang Li,Chao Fu,Yi Wang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6
A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.
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RNA binding protein QKI contributes to WT1 mRNA and suppresses apoptosis in ST cells
Xin Liu,Jia Guo,Mengjiao Zhou,Yuwei Yang,Mengdi Liang,Chunyan Bai,Zhihui Zhao,Boxing Sun 한국유전학회 2017 Genes & Genomics Vol.39 No.9
The RNA binding protein quaking (QKI), a key member of the STAR family, as an upstream gene could involve in much process including cell proliferation, apoptosis, differentiation and so on. However, the roles of QKI in germ cell, especially in swine testis (ST) cells, was not clear currently. And apoptosis plays important roles in the growth and development. The purpose of the present study was to clarify the relationship between QKI and apoptosis in ST cells. Firstly, our results showed that pEF1α- QKI and shQKI3 have clear effects on expression levels of QKI. Secondly, we established that QKI directly binds to WT1 3′UTR by binding with QRE-1 (2046–2052 bp, ACT AAC ) only. Furthermore, QKI overexpression significantly increased the expression levels of WT1 and Bcl-2. QKI also has the effect on delaying the degradation of WT1 mRNA. In addition, we verified that QKI had a significantly suppressed apoptosis in ST cells. Finally, pBI-WT1 could make up for shQKI3-induced decrease in WT1, Bcl-2 mRNA levels and suppress apoptosis in ST cells. The results demonstrated that QKI was an important regulatory factor that affects apoptosis by targeting WT1 gene.
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Yinhua Liu,Rui Sun,Yuwei Lu,Shiming Zhang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.10
The real-time process fault detection in the multi-station assembly process is always a challenging problem for auto body manufactures. Traditionally, the fault diagnosis approaches for variation source identification are divided into two categories, i.e. the pattern matching methods and model-based estimation ones based on the collected data set. The measurements provide effective process monitoring, but the real-time process fault diagnosis in the assembly process is still difficult with the traditional diagnosis techniques, and always depends on the engineering experience in practice. Based on the assembly process knowledge, including multi-station assembly hierarchy, fixture scheme, measurement characteristics and tolerances etc. in the multi-station, a knowledge-based diagnostic methodology and procedures are proposed with the measurements of each body in white for part/component defections and faulty assembly station identification. For the station involved with defective parts/components, the sub-coordinate system of the part/component is established reflecting its position and pose in the space, and then the relative pose matrix to the “normally build” pose is calculated based on the deviations of sub-coordinates of the parts in this station. Finally, the assembly process malfunctions are determined by a proposed rule-based strategy with the relative pose matrix in real time. A simple 3 stations assembly process with 5 sheet metal parts was analyzed and compared with the traditional diagnostic method to verify the effectiveness and stability of the proposed method.
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Sun, Yuwei,Liu, Jiaomin,Li, Yonggang,Fu, Chao,Wang, Yi The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6
A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.
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Guo, Jia,Liu, Xin,Yang, Yuwei,Liang, Mengdi,Bai, Chunyan,Zhao, Zhihui,Sun, Boxing Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.8
Objective: This study aimed to screen and identify the target genes of miR-375 in pig Sertoli (ST) cells and to elucidate the effect of miR-375 on the proliferation of ST cells. Methods: In this study, bioinformatics software was used to predict and verify miR-375 target genes. Quantitative polymerase chain reaction (PCR) was used to detect the relationship between miR-375 and its target genes in ST cells. Enzyme-linked immunosorbent assay (ELISA) of rearranged L-myc fusion (RLF) and hypoxia-induced gene domain protein 1A (HIGD1A) was performed on porcine ST cells, which were transfected with a miR-375 mimics and inhibitor to verify the results. Dual luciferase reporter gene assays were performed to assess the interactions among miR-375, RLF, and HIGD1A. The effect of miR-375 on the proliferation of ST cells was analyzed by CellTiter 96 AQueous One Solution Cell Proliferation Assay (MTS). Results: Five possible target genes of miR-375, including RLF, HIGD1A, colorectal cancer associated 2, POU class 3 homeobox 1, and WW domain binding protein 1 like, were found. The results of quantitative PCR suggested that mRNA expression of RLF and HIGD1A had a negative correlation with miR-375, indicating that RLF and HIGD1A are likely the target genes of miR-375. The ELISA results revealed that RLF and HIGD1A were negatively correlated with the miR-375 protein level. The luminescence results for the miR-375 group cotransfected with wild-type RLF and HIGD1A vector were significantly lower than those of the miR-375 group co-transfected with the blank vector or mutant RLF and HIGD1A vectors. The present findings suggest that RLF and HIGD1A are target genes of miR-375 and that miR-375 inhibits ST cell proliferation according to MTS analysis. Conclusion: It was speculated that miR-375 affects cell proliferation through its target genes, which play an important role in the development of testicular tissue.
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