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Modeling and Stability Issues of Voltage-source Converter-dominated Power Systems:A Review

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1530-1549页

作者： Liansong Xiong Xiaokang Liu Yonghui Liu fang zhuo School of Electrical Engineering Xi’an Jiaotong UniversityXi’an 710049China Department of Electronics Information and BioengineeringPolitecnico di Milano20133 MilanoItaly

With the substantive increase in the proportion of voltage-source converter(VSC)-based equipment,traditional power systems that primarily constituted of synchronous generators(SGs)gradually evolved into VSC-dominated *** the same time,there is an urgent need for modeling and stability assessment of such systems,since low inertia and weak damping features impair the ability of the systems to resist random *** works model the system dynamic processes from various domains(i.e.,time,frequency and energy),and analyze/determine the system stability under small or large *** them,small-signal stability assessments mainly adopt the time-domain analysis based on the state-space model while frequency-domain methods include the impedance model,phase-amplitude dynamics model,and static synchronous generator ***-signal stability assessments mainly exploit the time-domain simulation with detailed models(i.e.,continuous/discrete-time mixed model with differentialdifference-algebraic equations),and the energy-domain analysis is based on energy function *** paper presents a comprehensive review of existing modeling and stability analysis methods for VSC-dominated power systems,including their basic principles,key features,application scenarios and development *** technical issues related to modeling and stability analysis are also summarized.

关键词： Dynamic modeling power system stability analysis voltage-source converter(VSC)

Control strategy for microgrid under three-phase unbalance condition

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Journal of Modern Power Systems and Clean Energy 2016年第1期4卷 94-102页

作者： Hongtao SHI fang zhuo Hao YI Zhiqing GENG School of Electrical Engineering Xi’an Jiaotong UniversityXi’an 710000 China

Microgrid(MG) is generally developed at utility terminal which contains lots of unbalanced loads and distributed generations(DGs). The interaction between MG and the unbalance loads or DGs will degrades the control performance of interfaced inverter in MG and dramatically leads to MG voltage unbalance. In this paper, a negative-sequence compensation based three-phase voltage unified correction strategy is proposed. While MG operates in islanded mode, a positive virtual impedance control is used to eliminate the negative voltage resulted from the negative-sequence current,and then a positive-sequence voltage control loop and negative-sequence control loop are used to improve the inverter control performance. While MG operates in grid-tied mode,the inverter operates as a negative-sequence current source to compensate the negative-sequence currents of loads to guarantee the point of common coupling(PCC) voltage *** using the proposed strategy, the voltage control performance of inverter can be improved;the MG power quality can be enhanced significantly. Simulation and experimental results verify the effectiveness of the proposed method.

关键词： Microgrid Inverter Three-phase unbalance Negative compensation

Chaos Synchronization in Two Coupled Duffing Oscillators

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Chinese Physics Letters 2001年第11期18卷 1438-1441页

作者： fang Jian-Shu fang zhuo LIU Xiao-Juan RONG Man-Sheng Department of Physics Zhuzhou Teacher's CollegeZhuzhou 412007 The Key Laboratory of Biomedical Photonics Huazhong University of Science and TechnologyWuhan 430074 Department of Physics Xiangtan Teacher's CollegeXiangtan 411017

We have obtained two general unstable periodic solutions near the homoclinic orbits of two coupled Duffing oscillators with weak periodic perturbations by using the direct perturbation technique. Theoretical analysis reveals that the stable periodic orbits are embedded in the Melnikov chaotic attractors. The corresponding numerical results show that the phase portraits in the (x, u) and (y, v) planes are identical and are synchronized when the parameters of the two coupled oscillators are identical, but they are different and asynchronized when there is any difference between these parameters. It has been shown that the system parameters play a very important role in chaos control and synchronization.

关键词： technique. periodic identical

Study of machining indentations over the entire surface of a target ball using the force modulation approach

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International Journal of Extreme Manufacturing 2021年第3期3卷 64-72页

作者： Yuzhang Wang Yanquan Geng Guo Li Jiqiang Wang zhuo fang Yongda Yan Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education Harbin Institute of TechnologyHarbinHeilongjiang 150001People’s Republic of China Center for Precision Engineering Harbin Institute of TechnologyHarbinHeilongjiang 150001People’s Republic of China Research Center of Laser Fusion China Academy of Engineering PhysicsMianyangSichuan 621900People’s Republic of China

A modified five-axis cutting system using a force control cutting strategy was to machine indentations in different annuli on the entire surface of a target *** relationship between the cutting depths and the applied load as well as the microsphere rotation speed were studied experimentally to reveal the micromachining *** particular,aligning the rotating center of the high precision spindle with the microsphere center is essential for guaranteeing the machining accuracy of *** distance between adjacent indentations on the same annulus and the vertical distance between adjacent annuli were determined by the rotating speed of the micro-ball and the controllable movement of the high-precision stage,*** order to verify the feasibility and effect of the proposed cutting strategy,indentations with constant and expected depths were conducted on the entire surface of a hollow thin-walled micro-ball with a diameter of 1 *** results imply that this machining methodology has the potential to provide the target ball with desired modulated defects for simulating the inertial confinement fusion implosion experiment.

关键词： force modulation controllable indentations entire micro-ball surface microsphere center alignment

Numerical Investigations on Hydrodynamic Performance of An Open Comb-Type Breakwater Under Medium Water Levels

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China Ocean Engineering 2021年第6期35卷 866-877页

作者： fang zhuo CHENG Liang ZANG Zhi-peng SHEN Chen TIAN Ying-hui CHENG Ning Transport planning and Research Institute Ministry of TransportBeijing 100028China Laboratory for Traffic and Transport Planning Digitalization Beijing 100028China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Melbourne School of Engineering The University of MelbourneParkvilleVIC 3010Australia China Harbor Engineering Company Limited Beijing 100027China

The comb-type breakwater(CTB)has been proposed and investigated in recent years due to its advantages in terms of deep-water adaptability,material saving and water *** existing empirical formulae for CTBs have been so far restricted to the water level above the bottom of the superstructure,which mainly occurs under the high tides or storm ***,based on recent engineering applications and experimental observations,the most severe conditions for CTBs are more likely to occur under a medium water level,because impulsive wave pressure may occur due to interactions between waves and the special chamber in ***,during the most of construction and operation periods,the CTBs are mainly working under the medium water levels,i.e.,water levels below the bottom of the *** this study,the effects of main influence parameters on the horizontal wave force coefficient and wave transmission coefficient for open CTBs(with partially immersed side plates)under medium water levels were investigated based on a 3D numerical wave flume and corresponding empirical formulae were *** is indicated that the location of the side plate related to the main caisson has significant influence on the hydrodynamic performance of *** engineering applications,the location of the side plate can be designed at b/L≤0.15 or b/L≥0.3(where b is the distance between the side plate and the front face of the main caisson and L is the incident wave length)for efficiently lowering the horizontal wave force and wave *** flow mechanism of impulsive wave force on CTBs was revealed based on synchronous analyses of flow fields and pressure *** appropriate design of the height of the superstructure according to H/hD≤1.0 or H/hD≥1.5(where H is the incident wave height and hD is the distance between the still water level and the bottom of the superstructure),the likely impulsive wave pressure on the side plate can also be diminished.

关键词： numerical wave flume open comb-type breakwater horizontal wave force coefficient transmission coefficient medium water level

Inhibiting effect of melittin on pathogens of crops

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Chinese Science Bulletin 2007年第5期52卷 639-644页

作者： PAN LingZi NA Jie XING zhuo fang HongJun WANG GuanLin College of Life Science Liaoning Normal University Dalian 116029 China

The spectrum of antimicrobial effects of melittin were investigated on 19 pathogens by using a cylin-der-plate method with serial dilutions. Bacteriostatic efficiency and possible mechanistic effects were monitored via growth curves. The mechanism of inhibition was further analyzed by SDS-PAGE, flow cytometry and electron microscopy. Melittin had a wide inhibition spectrum and killed pathogens ef-fectively, and bacteriostatic action was influenced by factors such as pH and temperature. We eluci-dated three inhibitory mechanisms: melittin integrated with the cell membrane causing cell bursting and cytoplasm release, inhibited the synthesis of proteins and caused the cytoplasm to condense, and delayed pathogens in phase I (or phase G1) so that they could not complete the cell cycle. These re-sults suggest that melittin could serve as a broad-spectrum biological pesticide with fast-action and high-efficiency.

关键词：蜂毒肽作物病原菌抑制作用抑菌机制抗菌谱

Centro-parietal N200: An event-related potential component specific to Chinese visual word recognition

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Chinese Science Bulletin 2012年第13期57卷 1516-1532页

作者： ZHANG John X fang zhuo DU YingChun KONG LingYue ZHANG Qin XING Qiang Department of Psychology the Chinese University ofHong Kong Hong Kong China Medical College of Shantou University Shantou 515041 China Key Laboratory of Behavioral Science Institute of Psychology Chinese Academy of Sciences Beijing 100101 China International College of Chinese Language Studies Peking University Beijing 100871 China Department of Psychology Capital Normal University Beijing 100048 China Department of Psychology Guangzhou University Guangzhou 510006 China

Almost all written languages currently used in the world are alphabetic or phonologically-based scripts (e.g., English) whose word recognition involves discrimination of one-dimensional linear combinations of several dozens of letters or phonological units, except written Chinese whose vocabulary consists of a large number of block characters, the analysis of which relies on the extraction of 2-dimensional form information at multiple levels including radical, character, and multiple-character word. Whether the dramatic contrast between the 2 types of orthography leads to distinctive mental processes is a fundamental question in psycholinguistic research unanswered in the past three decades. Using event-related potentials and visual lexical decision tasks, we asked native Chinese speakers to discriminate between real Chinese words and pseudoor non-words and observed a widespread negative deflection with centro-parietal focus elicited 200 ms post-stimulus onset. This N200 response showed a clear and large amplitude enhancement upon word repetition and seems to be specific to Chinese as no similar effects had been reported in word recognition studies involving alphabetic scripts under similar experimental conditions. Further evidence showed that this N200 could not be attributed to non-linguistic sensori-perceptual processes, nor phonological or semantic processes, but likely reflects very early identification of the orthography of individual words involving extensive and higher-level visual analysis. Recently the first author proposed a meaning-spelling theory of written Chinese vocabulary proposing that the Chinese and alphabetic scripts are the only 2 possible logical types of mature human writing systems, and that the former is more thoroughly a visual language compared with the latter and thus shall emphasize more of visual processing. Reinforcing each other, the meaning-spelling theory and the discovery of the centro-parietal N200 reveal the uniqueness of Chines

关键词：事件相关电位 N200 视觉分析早期识别中国词汇英文字母成分

Safety and efficacy comparison of remimazolam and propofol for intravenous anesthesia during gastroenteroscopic surgery of older patients:A meta-analysis

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World Journal of Clinical Cases 2024年第7期12卷 1272-1283页

作者： fang-zhuo Li Cheng Zhao Yi-Xun Tang Ji-Tong Liu Department of Anesthesiology The First Affiliated Hospital of Hunan Normal University(Hunan Provincial People’s Hospital)Changsha 410005Hunan ProvinceChina Department of Anesthesiology Zhangjiajie People's HospitalZhangjiajie 427000Hunan ProvinceChina

BACKGROUND Remimazolam is characterized by rapid action and inactive *** is used as the general anesthetic for many clinical *** this study,we performed a meta-analysis to evaluate whether remimazolam is superior to propofol for gastroenteroscopy in older *** To compare the adverse events and efficacy of remimazolam and propofol during gastroenteroscopy in older *** The PubMed,Web of Science,the Cochrane Library databases were queried for the relevant key words"remimazolam,""and propofol,""and gastrointestinal endoscopy or gastroscopy."The search scope was"Title and Abstract,"and the search was limited to human studies and publications in *** studies wherein remimazolam and propofol were compared were included for the *** We selected seven randomized controlled trials involving 1445 cases for the *** reduced the hypotension(relative risk,RR=0.44,95%CI:0.29-0.66,P=0.000),respiratory depression(RR=0.46,95%CI:0.30-0.70,P=0.000),injection pain(RR=0.12,95%CI:0.05-0.25,P=0.000),bradycardia(RR=0.37,95%CI:0.24-0.58,P=0.000),and time to discharge[weighted mean difference(WMD)=-0.58,95%CI:-0.97 to-0.18,P=0.005],compared to those after propofol *** obvious differences were observed for postoperative nausea and vomiting(RR=1.09,95%CI:0.97-1.24,P=0.151),dizziness(RR=0.77,95%CI:0.43-1.36,P=0.361),successful sedation rate(RR=0.96,95%CI:0.93-1.00,P=0.083),or the time to become fully alert(WMD=0.00,95%CI:-1.08-1.08,P=0.998).CONCLUSION Remimazolam appears to be safer than propofol for gastroenteroscopy in older ***,further studies are required to confirm these findings.

关键词： Remimazolam Propofol Gastroenteroscopy Anesthesia Older adults Sedation Adverse events

Multi-objective optimization of stamping forming process of head using Pareto-based genetic algorithm

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Journal of Central South University 2015年第9期22卷 3287-3295页

作者：周杰卓芳黄磊罗艳 College of Material Science and Engineering Chongqing University

To obtain the optimal process parameters of stamping forming, finite element analysis and optimization technique were integrated via transforming multi-objective issue into a single-objective issue. A Pareto-based genetic algorithm was applied to optimizing the head stamping forming process. In the proposed optimal model, fracture, wrinkle and thickness varying are a function of several factors, such as fillet radius, draw-bead position, blank size and blank-holding force. Hence, it is necessary to investigate the relationship between the objective functions and the variables in order to make objective functions varying minimized simultaneously. Firstly, the central composite experimental(CCD) with four factors and five levels was applied, and the experimental data based on the central composite experimental were acquired. Then, the response surface model(RSM) was set up and the results of the analysis of variance(ANOVA) show that it is reliable to predict the fracture, wrinkle and thickness varying functions by the response surface model. Finally, a Pareto-based genetic algorithm was used to find out a set of Pareto front, which makes fracture, wrinkle and thickness varying minimized integrally. A head stamping case indicates that the present method has higher precision and practicability compared with the "trial and error" procedure.

关键词： stamping forming heads finite element analysis central composite experimental design response surface methodology multi-objective genetic algorithm