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characteristic analysis of Power Oscillations Caused by Disharmony Among Voltage-source-controlled Units in Three-terminal Local Power Grid

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1295-1308页

作者： Qiyi Yu Yi Tang School of Electrical Engineering Southeast UniversityNanjing 210018China

Previous studies have demonstrated that disharmo-ny among voltage-source-controlled units(VSCUs)may occur on an alternating current(AC)transmission or distribution line under steady-state operating conditions(SSOCs)or quasi-static operating conditions(QSSOCs).As the studies on frequency dis-harmony have been expanded to multiple disharmonized vS-CUs in the local power grid,its adverse effects on AC lines and equivalent load(EL)at the bus without active voltage control ability(non-active bus)need to be investigated ***-ering the locality of disharmony and common topological con-nections among VSCUs,this paper adopts a Y-type three-termi-nal local power grid(LPG)as the research *** dishar-mony among the three VSCUs is ***,for the load at non-active bus,the formulas for single-phase instantaneous voltage,load current,load power,as well as average power un-der disharmony operating conditions(DOCs)are *** characteristic indicators of the above electrical quantities are defined,which can measure the amplification and reduction de-grees of the above electrical quantities before and after ***,for the line directly connected to VSCUs,the formulas for single-phase instantaneous line current and power and the average power under DOCs are *** character-istic indicators of power flow are defined,which can be used to quantify the peak amplification impact of oscillation before and after ***,the case study on the Y-type three-terminal LPG under the single-disharmony and the multi-dis-harmony switching scenarios indicates that the long-period pow-er oscillation caused by disharmony may occur in the load flow at the non-active bus and the line *** oscillation causes a serious decrease in load capability and a significant amplifica-tion of the peak of line power oscillation.

关键词： New power system power oscillation disharmony voltage-source-controlled unit(VSCU) characteristic analysis

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characteristic analysis FOR STRESS WAVE PROPAGATION IN TRANSVERSELY ISOTROPIC FLUID-SATURATED POROUS MEDIA

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Applied Mathematics and Mechanics(English Edition) 2004年第6期25卷 656-663页

作者：刘颖刘凯欣 Department of Mechanics and Engineering Science Peking UniversityBeijing 100871P.R.China Department of Mechanics Engineering Shandong University of TechniqueZiboShandong 255000P.R.ChinaDepartment of Mechanics and Engineering SciencePeking UniversityBeijing 100871P.R.China

According to generalized characteristic theory, a characteristic analysis for stress wave propagation in transversely isotropic fluid-saturated porous media was performed. The characteristic differential equations and compatibility relations along bicharacteristics were deduced and the analytical expressions for wave surfaces were obtained. The characteristic and shapes of the velocity surfaces and wave surfaces in the transversely isotropic fluid-saturated porous media were discussed in detail. The results also show that the characteristic equations for stress waves in pure solids are particular cases of the characteristic equations for fluid-saturated porous media.

关键词： characteristic analysis wave surface fluid-saturated porous medium transversely isotropic stress wave

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characteristic analysis and design of near moon abort trajectory for manned lunar landing mission

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Science China(Technological Sciences) 2010年第11期53卷 3129-3137页

作者： HUANG WenDe XI XiaoNing WANG Wei College of Mechatronics Engineering and Automation National University of Defense TechnologyChangsha 410073China College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China School of Surveying and Spatial Information System University of New South WalesSydneyNSW 2052Australia

The safety of astronauts would be severely threatened if the lunar-landing spacecraft were under an emergency during the near moon phase of flight, which was far from the Earth. For the problem of mission abort caused by the main engine (service propulsion system, SPS) failure during lunar orbit insertion, firstly, the family of trajectories resulted from SPS premature shutdown and corresponding abort trajectories were analyzed; then an algorithm that can be applied to the near moon abort trajectories was proposed using patched-conic technique. The characteristics of the abort trajectory, such as energy consumption and return time of flight, were analyzed and presented. Finally, simulation examples were given to demonstrate various cases of near moon SPS failure. The results of the simulation have validated the approach proposed.

关键词： manned lunar landing mission abort trajectory near moon phase characteristic analysis patched-conic technique

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characteristic analysis of Atmospheric Electric Field in Contaminated Areas

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Meteorological and Environmental Research 2014年第2期5卷 31-34,40页

作者： Fu Yaping Yang Shigang Hao Xiaozhi Li Fang Lightning Protection Monitoring Center of Shanxi Province

[Objective] The research aimed to analyze characteristics of atmospheric electric field in polluted area. [Method] By using data of atmospheric electric field meter in Taiyuan in 2009, daily and annual changes of atmospheric electric field in Taiyuan were analyzed. [ Result] Atmospheric electric field intensity in Taiyuan was higher than that in other areas. Daily change was double-peak double-valley type. The first highest value appeared at nightfall, and the second highest value was before the noon. The first lowest value appeared in early morning, while the second low- est value appeared after the noon. Annual change was single-peak single-valley type. The maximum appeared in winter, while the minimum ap- peared in summer. [ Conclusion] When forecasting thunderstorm, in the area with higher aerosol content, alarm threshold of electric field should be adjusted via comparison with actual observation, which had very strong regional characteristics. By analyzing real-time monitoring data of atmospheric electric field, thunderstorm forecast could be realized, and timeliness and accuracy of warning and forecast could be increased.

关键词： Atmospheric electric field Polluted area characteristic analysis China

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characteristic analysis and Forecast of Continuous High-temperature Weather in Xingtai Area of Hebei

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Meteorological and Environmental Research 2014年第10期5卷 3-7页

作者： Wang Xiaojuan Wang Congmei Liu Jin Xingtai Meteorological Bureau of Hebei Province

Through the analysis of durative high-temperature weather process occurred in Xingtai area in June of 2010,and the statistics on relative humidity and 850 hPa of temperature on high temperature day in Xingtai area during 2001- 2010,it was concluded that 500 h Pa of stable warm high-pressure ridge situation and 850 hPa of strong warm air mass control were favorable circulation situations for the formation of high temperature;sinking and adiabatic warming of high-altitude air mass was an important cause of high temperature weather generation; ground humidity at 14： 00 was small,that is,the atmosphere was very dry,and it was sunny-cloudy（ high cirrus） weather,which was a necessary condition for the high temperature weather; westerly at some time was favorable condition for high temperature; 850 h Pa of temperature prediction at the station was the *** the forecasted 850 h Pa of station temperature was 21 ℃ and above,it was reminded the forecasters in the high-temperature forecast process.

关键词： Continuous high-temperature weather characteristic analysis Forecast Xingtai area China

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characteristic analysis of Partial Discharge’s Electromagnetic Signal Based on Wavelet Transform

Characteristic Analysis of Partial Discharge’s Electromagne...

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ICEMI'2005第七届国际电子测量与仪器学术会议

作者： Zhou Lixing1 Li Weiguo2 (1 Changsha University of Science & Technology ChangSha 410076 China) (2 North China Electric Power University Beijing 010003 China)

In this paper, the wavelet multi- resolution analysis of typical partial discharge (PD) radiating electromagnetic signal is introduced. The wavelet spectrum distribution of typical PD electromagnetic

关键词： Partial discharge wavelet transform characteristic analysis electromagnetic signal.

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Rockburst prediction and prevention in underground space excavation

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Underground Space 2024年第1期14卷 70-98页

作者： Jian Zhou Yulin Zhang Chuanqi Li Haini He Xibing Li School of Resources and Safety Engineering Central South UniversityChangsha 410083China Laboratory 3SR CNRS UMR 5521Grenoble Alpes UniversityGrenoble 38000France

The technical challenges associated with deep underground space activities have become increasingly *** these challenges,one major concern is the assessment of rockburst risks and the instability of rock *** research has been conducted by numerous scholars to mitigate the risks and prevent occurrences of rockburst through various assessment *** incidents commonly occur during the excavation of hard rock in underground environments,posing severe threats to personnel safety,equipment integrity,and operational ***,it is crucial to systematically document real cases of rockburst,allowing for a comprehensive understanding of the underlying mechanisms and triggering *** understanding will contribute to the advancement of rockburst prediction and prevention *** selection of an appropriate rockburst assessment method is a fundamental aspect in underground ***,there is a limited number of studies that summarize and compare different prediction and prevention methods of *** paper aims to address this gap by analyzing global trends using CiteSpace software since *** discusses rockburst classification and characteristics,comprehensively reviews research findings related to rockburst prediction,including empirical,simulation,mathematical modeling,and microseismic monitoring ***,the paper presents a compilation of current rockburst prevention ***,the paper emphasizes the significance of control strategies,which provide key insights into the effective utilization of stored energy within ***,the paper concludes by suggesting six directions for implementing intelligent management techniques to mitigate hazards during underground operations and reduce the probability of rockburst incidents.

关键词： Rockburst Underground space Scientometric analysis characteristic analysis Rockburst prediction Rockburst prevention

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characteristics analysis for cold water patches off the Jiangsu coast in the last 35a

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Acta Oceanologica Sinica 2018年第11期37卷 19-25页

作者： ZHU Shouxian HE Zhanyuan ZHANG Wenjing XIE Shijian XU Yucheng College of Oceanography Hohai UniversityNanjing 210098China College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China Zhejiang Surveying of Estuary and Coast Hangzhou 310008China

The daily and monthly-mean characteristics of cold water patches （CWPs） off the Jiangsu coast in 35 a of 1982-2016 are examined based on advanced very high resolution radiometer （AVHRR） data. Most of the CWPs are found to occur in the warm and hot months （May-September）, with some CWPs in the cool and cold months （October-April）. The average radius and intensity of the monthly-mean CWPs are about 81 km and 0.6℃, respectively. The average difference in the sea surface temperature （SST） between the centers of the CWPs and the nearshore is about 2.0℃. The correlation analysis between the CWPs, winds and tides indicates that most of the CWPs occurred during the southerly winds, with some CWPs occurring during the northerly winds. The average intensity of the CWPs during spring tides is slightly stronger than that during neap tides in the warm and hot months, and the difference is very small in the cool and cold months.

关键词： Jiangsu coast cold water patch characteristic analysis wind tide

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Complexity analysis of precipitation in changing environment in Chien River Basin,China

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Water Science and Engineering 2011年第2期4卷 133-142页

作者： Qing-hua LUAN Hao WANG Da-zhong XIA College of Water Conservancy and Hydropower Hebei University of Engineering Handan 056021 P. R. China Department of Water Resources China htstitute of Water Resources and Hydropower Research Beijing 100038 P. R. China College of Hydrology and Water Resources Hohai University Nanjing 210098 P. R. China

The hydrological processes influenced by the multiple factors of climate, geography, vegetation, and human activities are becoming more and more complex, which is an important characteristic of hydrological systems. The different complexity distributions of precipitation processes of the Chien River Basin （a sub-basin of the Minjiang Basin） in two periods （from 1952 to 1980, and from 1981 to 2009） are illustrated using the fractal based on the continuous wavelet transform （CWT）. The results show that （1） at the basin scale the precipitation process in the latter period is more complex than in the former period; （2） the maximum value of the complexity distribution moved from the east to the middle; and （3） through analysis of the time-information and space-information concealed in this complexity change, the precipitation characteristics in the changing environment in the basin can be illuminated. This study could provide a reference for research on disaster pre-warning in changing environments and for integrated water resources management in the local basin.

关键词： characteristic analysis precipitation complexity continuous wavelet transform fractal: Chien River Basin

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analysis of characteristics of a pneumatic miniature robotic system

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High Technology Letters 2008年第1期14卷 35-39页

作者：于莲芝 Yan Guozheng Ma Guangying Zan Peng School of Electronic Information and Electrical Engineering Shanghai Jiaotong University Shanghai 200240 P.R. China College of Optoelectric ＆ Electronic Information Engineering University of Shanghai for Science and Technology Shanghai 200093 P.R. China

This paper described the structure of a flexible miniature robotic system which can move in human cavities, and then analyzed the characteristics of the robotic system in detail. The mobile mechanism of the miniature robotic system is soft; it makes inchworm-like movement driven by a 3-DOF pneumatic rubber actuator and holds its positions by air chambers. The driving characteristic models in axial and bending directions of the actuator were set up and the kinemics equations of the robotic system were set up. Experiments had been done through an electro-pressure control system, by which the pneumatic robotic system can be controlled with high accuracy. It is suitable for moving in human cavities for medical inspection.

关键词： miniature robotic system pneumatic rubber actuator characteristic analysis

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