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      • SCIESCOPUSKCI등재

        Research on a Multi-Objective Control Strategy for Current-source PWM Rectifiers under Unbalanced and Harmonic Grid Voltage Conditions

        Geng, Yi-Wen,Liu, Hai-Wei,Deng, Ren-Xiong,Tian, Fang-Fang,Bai, Hao-Feng,Wang, Kai The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

        Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current $2^{nd}$ order fluctuations, and 3) elimination of the DC-current $2^{nd}$ and $6^{th}$ order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

      • SCIESCOPUSKCI등재

        An Improved Active Damping Method with Capacitor Current Feedback

        Geng, Yi-Wen,Qi, Ya-Wen,Liu, Hai-Wei,Guo, Fei,Zheng, Peng-Fei,Li, Yong-Gang,Dong, Wen-Ming The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

        Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, $f_s/6$. However, the resonance frequency ($f_r$) of an LCL-type filter is usually designed to be less than half the sampling frequency ($f_s$) with the symmetry regular sampling method. Therefore, ($f_s/6$, $f_s/2$) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, $f_s/6$ to (0, $f_s/2$), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, $f_s/2$). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain $K_p$. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.

      • KCI등재

        Identification and expression profiles of chitin deacetylase genes in the rice leaf folder, Cnaphalocrocis medinalis

        Hai-Zhong Yu,Ming-Hui Liu,Xue-Yang Wang,Xin Yang,Wan-Ling Wang,Lei Geng,Dong Yu,Xue-Lan Liu,Gui-Ying Liu,Jia-Ping Xu 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.3

        Chitin deacetylase (CDA) is an insect chitin degradation enzyme that catalyzes the deacetylation of chitin to form chitosan. In this study, combination of rapid-amplification of cDNA ends (RACE) technology with Cnaphalocrocis medinalis transcriptome database analysis revealed the presence of at least five C. medinalis CDAs (CmCDAs), which were CmCDA1, CmCDA2, CmCDA4, CmCDA5, and CmCDA6. The cDNA sequences of CmCDA1, CmCDA2, and CmCDA4 hadwhole open reading frame (ORF) for further analysis. Phylogenetic analysis indicated that insect CDAs could be categorized into five groups. CmCDAs' structural domain analysis revealed that all three CDAs contained the chitin deacetylase-like catalytic domain. CmCDA1 and CmCDA2 belong to Group I because they both contain the chitin-binding peritrophin-A domain (ChBD), low-density lipoprotein receptor class A domain (LDLa), and chitin deacetylase-like catalytic domain. CmCDA4 only contains ChBD and chitin deacetylase-like catalytic domain thus belongs to Group III. Tissue and developmental stage expression analysis showed that the expression levels of CmCDA1, CmCDA2, and CmCDA4 are significantly higher in the head than other tissues and also significantly higher in adults than in larvae. CmCDA5 had significantly higher expression in the integument than other tissues, suggesting potential roles in the process of degradation of chitin. In contrast, CmCDA5 showed relatively high expression in larvae. In conclusion, this study analyzed the cDNA sequences of three CDA genes and determined their expression and molecular characteristics, which provided a new sequence resource and improved the development of bio-pesticides and the biological pest control and contributed to management of this important agricultural pest.

      • KCI등재

        Effects of Narrative Exposure Therapy for Treating Depressive and Anxious Disorders: A Systematic Review and Meta-Analysis

        Chen Geng,Miao Zhang,Lily Zhang,Hai Yin,Suyun Wang 대한신경정신의학회 2024 PSYCHIATRY INVESTIGATION Vol.21 No.4

        Objective Narrative exposure therapy (NET) has been used in various contexts for the treatment of the effects of trauma, with promising results in clinical trials. However, its effects on anxiety and depression are still unclear. The present study is a systematic review and meta-analysis of the effects of NET on depression and anxiety.Methods The Embase, Cumulative Index of Nursing and Allied Health Literature, PubMed, Web of Science core collection, Cochrane Library, Chinese National Knowledge Infrastructure, Chinese Biomedical Database, and Wangfang databases were searched from the earliest records to March 2023. Two researchers independently screened the literature, extracted data, evaluated the risk of bias, and cross-checked the data. Meta-analysis was performed using the program RevMan 5.3.Results Eleven randomized controlled trials with a total of 754 participants were included in the study. The results showed that NET reduced both the depression (standard mean difference [SMD]=-0.51, 95% confidence interval [CI] -0.73–-0.29, p<0.00001) and anxiety (SMD=-0.65, 95% CI -1.13–-0.18, p=0.007) scores of the patients. Furthermore, NET was found to alleviate negative emotions associated with guilt (mean difference [MD]=-3.60, 95% CI -5.52–-1.68, p=0.0005) and negative change (MD=-5.80, 95% CI -9.76–-1.83, p=0.004).Conclusion This analysis showed that NET can alleviate depression and anxiety. It may thus be used in clinical settings to alleviate patients’ negative feelings and aid their overall recovery.

      • KCI등재

        Investigation into performance enhancements of Li–S batteries via oxygen-containing functional groups on activated multi-walled carbon nanotubes using Fourier transform infrared spectroscopy

        Yu Hai Wang,Zhe Dai,Chao Yue Zhang,Guo Wen Sun,Zhong Wei Lu,Xiu Ping Gao,Geng Zhi Sun,Wei Lan,Zhen Xing Zhang,Xiao Jun Pan,Jin Yuan Zhou 한국물리학회 2020 Current Applied Physics Vol.20 No.9

        It was demonstrated that the electrochemical performance enhancements in KOH-activated carbon materials should be mainly due to the created polar oxygen-containing functional groups (OFGs, such as such as C–O, C–– O, –OH, and O–C–– O), while the role of each OFGs on the electrochemical enhancements is still unclear. In this work, KOH activation treatments were systematically conducted on carbon nanotubes (CNTs) to explore the role of each OFG on the performance enhancements of Li–S batteries (LSBs). Results showed that the capacity of activated-CNT-sulfur (a-CNT-S) cathodes is 33% higher than that of the pristine CNT-S cathodes, and their rate capability and cycling stability are also enhanced. And the electrochemical analysis combining with Fourier transform infrared spectroscopy indicated that the formed C–O bonds are the real factor for the enhanced electrochemical performances of a-CNT-S cathodes. Furthermore, the optimal activation conditions on CNTbased cathodes for LSBs were optimized to be 10 min at 700 ℃.

      • In Vivo Evaluation of Curcumin-loaded Nanoparticles in a A549 Xenograft Mice Model

        Yin, Hai-Tao,Zhang, De-Geng,Wu, Xiao-Li,Huang, Xin-En,Chen, Gang Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

        Curcumin (Cum) has been reported to have potential chemo-preventive and chemotherapeutic activity through influencing various processes, inducing cell cycle arrest, differentiation and apoptosis in a series of cancers. However, the poor solubility of Cum limits its further applications in the treatment of cancer. We have previously reported Cum-loaded nanoparticles (Cum-NPs) prepared with amphilic methoxy poly(ethylene glycol)-polycaprolactone (mPEG-PCL) block copolymers. The current study demonstrated superior antitumor efficacy of Cum-NPs over free Cum in the treatment of lung cancer. In vivo evaluation further demonstrated superior anticancer effects of Cum-NPs by delaying tumor growth compared to free Cum in an established A549 transplanted mice model. Moreover, Cum-NPs showed little toxicity to normal tissues including bone marrow, liver and kidney at a therapeutic dose. These results suggest that Cum-NPs are effective to inhibit the growth of human lung cancer with little toxicity to normal tissues, and could provide a clinically useful therapeutic regimen. They thus merit more research to evaluate the feasibility of clinical application.

      • KCI등재

        Research on a Multi-Objective Control Strategy for Current-source PWM Rectifiers under Unbalanced and Harmonic Grid Voltage Conditions

        Yi-Wen Geng,Hai-Wei Liu,Ren-Xiong Deng,Fang-Fang Tian,Hao-Feng Bai,Kai Wang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

        Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, 5th and 7th order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current 2nd order fluctuations, and 3) elimination of the DC-current 2nd and 6th order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, 5th and 7th order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

      • KCI등재

        An Improved Active Damping Method with Capacitor Current Feedback

        Yi-Wen Geng,Ya-Wen Qi,Hai-Wei Liu,Fei Guo,Peng-Fei Zheng,Yong-Gang Li,Wen-Ming Dong 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

        Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, fs/6). However, the resonance frequency (fr) of an LCL-type filter is usually designed to be less than half the sampling frequency (fs) with the symmetry regular sampling method. Therefore, (fs/6, fs/2) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, fs/6) to (0, fs/2), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, fs/2). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain Kp. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.

      • KCI등재

        TP53I11 suppresses epithelial-mesenchymal transition and metastasis of breast cancer cells

        ( Tongqian Xiao ),( Zhongjuan Xu ),( Hai Zhang ),( Junsa Geng ),( Yong Qiao ),( Yu Liang ),( Yanzhen Yu ),( Qun Dong ),( Guangli Suo ) 생화학분자생물학회(구 한국생화학분자생물학회) 2019 BMB Reports Vol.52 No.6

        Epithelial-mesenchymal transition (EMT) is widely-considered to be a modulating factor of anoikis and cancer metastasis. We found that, in MDA-MB-231 cells, TP53I11 (tumor protein P53 inducible protein 11) suppressed EMT and migration in vitro, and inhibited metastasis in vivo. Our findings showed that hypoxic treatment upregulated the expression of HIF1α, but reduced TP53I11 protein levels and TP53I11 overexpression reduced HIF1α expression under normal culture and hypoxicconditions, and in xenografts of MDA-MB-231 cells. Considering HIF1α is a master regulator of the hypoxic response and that hypoxia is a crucial trigger of cancer metastasis, our study suggests that TP53I11 may suppress EMT and metastasis by reducing HIF1α protein levels in breast cancer cells. [BMB Reports 2019; 52(6): 379-384]

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