Inertia Parameter Selection Method for HVDC Converter Station Based on VSG Control

Yong Shi,Ce Fang,Lei Chen,Meiqing Mao,Zhong Chen 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

With the purpose of improving the frequency support capability of high voltage direct current (HVDC) transmission equipment and ensuring the stable and reliable operation for the receiving end power grid, a virtual synchronous generator (VSG) control algorithm for high voltage direct current converter was proposed in this paper. The virtual synchronous generator control method is analyzed in detail, and the small-signal model of grid-tied high voltage direct current converter is established, and further established the small signal-model of the three-area power system. On the basis of the proposed models, considering the factors such as diff erent short circuit ratios, decoupling performance, stability, dynamics, the selection principle of inertia factor J and damping factor D of virtual synchronous generator is proposed. Finally, the eff ectiveness of the proposed inertia and damping coeffi cient selection method is verifi ed by simulation.

Cloning and expression of a wild eggplant cytochrome P450 gene, StoCYP77A2, involved in plant resistance to Verticillium dahliae

Liu Yang,Ce Shi,Xiaoying Mu,Chao Liu,Ke Shi,Wen-jiao Zhu,Qing Yang 한국식물생명공학회 2015 Plant biotechnology reports Vol.9 No.4

Plant P450s play an important role in plant response to environmental stimuli, especially to pathogen challenge, besides leading to the biosynthesis of secondary metabolites. In this work, a Verticillium dahliae-induced cDNA sequence was cloned from wild eggplant Solanum torvum and designated StoCYP77A2. StoCYP77A2 encodes a 511-amino acid peptide that shows sequence homology to the plant CYP77 family. StoCYP77A2 is expressed in a tissue-specific manner with the highest expression level in stem. The expression level of StoCYP77A2 was increased in wild eggplants which were infected with Verticillium dahlia. We expressed StoCYP77A2 in V. dahliae-sensitive tobacco, and the transgenic tobacco plants were more resistant to V. dahliae infection than the wild type. Protein extraction of transgenic tobacco showed strong antifungal activity against V. dahliae, indicating that StoCYP77A2 may be involved in the synthesis of some antimicrobial compounds. These results suggest that StoCYP77A2 plays a role in plant defense to V. dahliae infection.

A Novel Research of ZVZCS Synchronous Rectification Converter Based on Phase-shifted Full-bridge Control

Zhou Yongqin,Huang Ce,Chen Junjie,Shi Guijun,Zhou Meilan 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.6

Due to synchronous rectification based on Phase-shift full bridge converter is difficult to work in a state of soft switch, to solve this problem, this paper sets out an control approach of synchronous rectification based on the ZVZCS phase-shifted full-bridge, and the drive signal of synchronous rectification side uses leading-leg drive waveform after a certain time delay and applies the resonant principle in the switching process,not only keeping full bridge ZVZCS soft switching but also realizing MOSFET of the synchronous rectification ZVS. The simulation of saber and experimental research show that the converter has a good performance.

Theoretical insight into the carrier mobility anisotropy of hole transport material Spiro-OMeTAD

Guanghao Meng,Yantao Shi,Xuedan Song,Min Ji,Yuan Xue,Ce Hao 한국물리학회 2017 Current Applied Physics Vol.17 No.10

All-solid-state organic-inorganic halide perovskite solar cells (PSCs) have attracted wide attention due to the rapid progress of power conversion efficiency in recent years. Hole transport material (HTM) in PSCs plays the role of extracting and transporting photo-excited holes. Anisotropy of carrier mobility is one important property for semiconductors, however, which still remains unclear for the dominant HTM spiro-OMeTAD used in PSCs. Based on Density Functional Theory (DFT) and Marcus theory, we for the first time conducted investigations on the anisotropy of carrier mobility along representative crystal planes of spiro-OMeTAD by recombination energy l and electronic coupling integral V. Results indicate that the holes and electrons show transport orientations consistency parallel to the (010), (101) and (111) crystal planes while inconsistency was found parallel to (100), (110), (011) and (001) crystal planes (with an angle ranged from 40 to 70 between the hole and electron transport directions). Our work embodies the theoretical significance of controllable and oriented fabrication of HTM in PSCs.

Compressive force regulates ephrinB2 and EphB4 in osteoblasts and osteoclasts contributing to alveolar bone resorption during experimental tooth movement

Jianhua Hou,Yanze Chen,Xiuping Meng,Ce Shi,Chen Li,Yuanping Chen,Hongchen Sun 대한치과교정학회 2014 대한치과교정학회지 Vol.44 No.6

Objective: To investigate the involvement of ephrinB2 in periodontal tissue remodeling in compression areas during orthodontic tooth movement and the effects of compressive force on EphB4 and ephrinB2 expression in osteoblasts and osteoclasts. Methods: A rat model of experimental tooth movement was established to examine the histological changes and the localization of ephrinB2 in compressed periodontal tissues during experimental tooth movement. RAW264.7 cells and ST2 cells, used as precursor cells of osteoclasts and osteoblasts, respectively, were subjected to compressive force in vitro. The gene expression of EphB4 and ephrinB2, as well as bone-associated factors including Runx2, Sp7, NFATc1, and calcitonin receptor, were examined by quantitative real-time polymerase chain reaction (PCR). Results: Histological examination of the compression areas of alveolar bone from experimental rats showed that osteoclastogenic activities were promoted while osteogenic activities were inhibited. Immunohistochemistry revealed that ephrinB2 was strongly expressed in osteoclasts in these areas. Quantitative real-time PCR showed that mRNA levels of NFATc1, calcitonin receptor, and ephrinB2 were increased significantly in compressed RAW264.7 cells, and the expression of ephrinB2, EphB4, Sp7, and Runx2 was decreased significantly in compressed ST2 cells. Conclusions: Our results indicate that compressive force can regulate EphB4 and ephrinB2 expression in osteoblasts and osteoclasts, which might contribute to alveolar bone resorption in compression areas during orthodontic tooth movement.

Simultaneous Modulated Accelerated Radiation Therapy and Concurrent Weekly Paclitaxel in the Treatment of Locally Advanced Nasopharyngeal Carcinoma

Xie, Cong-Ying,Jin, Xian-Ce,Deng, Xia,Xue, Sheng-Liu,Jing, Zhao,Su, Hua-Fang,Wu, Shi-Xiu Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Objectives: To evaluate the feasibility and efficacy of simultaneous accelerated radiation therapy (SMART) and concurrent weekly paclitaxel in the treatment of locally advanced nasopharyngeal carcinoma. Methods: Forty-one patients with pathologically confirmed nasopharyngeal carcinoma were treated by SMART with concurrent weekly paclitaxel. Daily fraction doses of 2.5 Gy and 2.0 Gy were prescribed to the gross tumor volume (GTV) and clinical target volume (CTV) to a total dose of 70 Gy and 56 Gy, respectively. Paclitaxel of $45mg/m^2$ was administered concurrently with radiation therapy every week. Adjuvant chemotherapy was given four weeks after the completion of the radiotherapy (RT) if the tumor demonstrated only a partial response (PR). Results: All patients completed the radiotherapy (RT) course. Adjuvant chemotherapy was administered to 12 patients due to PR. The CR (complete remission) rate was 82.9% three months after RT. Thirty-nine (95.1%) patients completed the concurrent weekly chemotherapy with paclitaxel, and two patients skipped their sixth course. Seven patients had a 15% dosage reduction at the fifth and sixth course due to grade 3 mucositis. The median follow-up was 30 (range, 14-42) months. The three-year overall survival (OS), metastases-free survival (MFS), and local control rates were 77.0%, 64.4%, and 97.6%, respectively. No correlation between survival rate and T or N stage was observed. Grade 3 acute mucositis and xerostomia were present in 17.1% and 7.1%, respectively. Conclusion: SMART with concurrent weekly paclitaxel is a potentially effective and toxicity tolerable approach in the treatment of locally advanced NPC.

Molecular simulation of adsorption of NO and CO2 mixtures by a Cu-BTC metal organic framework

Guanghao Meng,Xuedan Song,Min Ji,Juanyuan Hao,Yantao Shi,Suzhen Ren,Jieshan Qiu,Ce Hao 한국물리학회 2015 Current Applied Physics Vol.15 No.9

Environmental problems due to the discharge of gases, including NO and CO2, in addition, diseases caused by improper concentration of NO and CO2 in vivo must be resolved. In this study, Grand canonical Monte Carlo (GCMC) simulations are combined with density functional theory (DFT) to calculate the adsorption of NO and CO2 from a dual-component mixture to the Cu-BTC metal organic framework. The results show that the adsorption isotherms for various molar ratios of the gaseous mixture followed a Langmuir distribution. At higher pressures more CO2 than NO was adsorbed by Cu-BTC, with NO showing a tendency to desorb. However, better results for adsorption of NO were observed at lower pressures. For the different pressure and molar ratios of the gaseous mixture examined, more CO2 than NO was always adsorbed. Compared with three-way catalysts, Cu-BTC offers benefits to adsorption of CO2 and NO from gaseous mixtures without increased durability problems.