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Steady-state Voltage Security-constrained Optimal Frequency Control for Weak HVDC Sending-end AC Power Systems

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 658-669页

作者： qiangqiang wang Liangzhong Yao Jian Xu Yuping Zheng Wei Li Wei wang School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network(Wuhan University) Wuhan 430072China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation(State Grid Electric Power Research Institute)Nanjing 211106China

Due to the fact that a high share of renewable energy sources(RESs)are connected to high-voltage direct current(HVDC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVDC sending-end AC power systems have *** has resulted in potential system operating problems such as overvoltage and overfrequency,which occur simultaneously when block faults exist in the HVDC *** this study,a steady-state voltage security-constrained optimal frequency control method for weak HVDC sending-end AC power systems is *** integrated virtual inertia control of RESs is employed for system frequency *** dynamic reactive power compensation devices are utilized to control the voltage of all nodes meet voltage security ***,an optimization model that simultaneously considers the frequency and steady-state voltage security constraints for weak HVDC sending-end AC power systems is *** optimal control scheme with the minimum total cost of generation tripping and additional dynamic reactive power compensation required is obtained through the optimization *** are conducted on a modified IEEE 9-bus test system and practical Qing-Yu line commutated converter based HVDC(LCC-HVDC)sending-end AC power system to verify the effectiveness of the proposed method.

关键词： Renewable energy source(RES) high-voltage direct current(HVDC) AC power system optimal frequency control steady-state voltage security dynamic reactive power compensation

Low-latitude hydroclimate changes related to paleomagnetic variations during the Holocene in coastal southern China

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Frontiers of Earth Science 2024年第2期18卷 324-335页

作者： Tingwei ZHANG Xiaoqiang YANG Jian YIN Qiong CHEN Jianfang HU Lu wang Mengshan JU qiangqiang wang School of Earth Science and Engineering/Guangdong Provincial Key Laboratory of Geodynamics and Geohazards/Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Sun Yat-sen UniversityGuangzhou 510275China Institute of Cultural Heritage Shandong UniversityQingdao 266237China State Key Laboratory of Organic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China College of Urban and Environmental Sciences Peking UniversityBeijing 100871China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China

The variations in precipitation have displayed a complex pattern in different regions since the *** formation processes may have a significant impact on precipitation,especially during the tropical marine processes and summer monsoon which convey abundant water vapor to coastal southern China and inland ***,we use two 7500 year sedimentary records from the Pearl River Delta and the closed Maar Lake,respectively,in coastal southern China to reconstruct the mid-to-late-Holocene humidity variability and explore its possible relationship with cloud cover modulated by the Earth’s magnetic fields(EMF).Our proxy records document an apparent increase in wetness in coastal southern China between 3.0 and 1.8 kyr *** apparent increase in humidity appears to be consistent with the lower virtual axial dipole moments and,in turn,with a lower *** correlation suggests that the EMF might have been superimposed on the weakened monsoon to regulate the mid-to-late-Holocene hydroclimate in coastal southern China through the medium of galactic cosmic rays,aerosols,and cloud ***,further investigations are needed to verify this interaction.

关键词： hydroclimate variations Earth’s magnetic field coastal southern China the Holocene epoch

Longitudinal gut fungal alterations and potential fungal biomarkers for the progression of primary liver disease

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Science China(Life Sciences) 2024年第6期67卷 1183-1198页

作者： Shiman Jiang Lvwan Xu Yanfei Chen Zheyue Shu Longxian Lv Yuxi Zhao Kefan Bi Sisi Yang qiangqiang wang Lanjuan Li State Key Laboratory for Diagnosis and Treatment of Infectious Diseases National Clinical Research Center for Infectious DiseasesNational Medical Center for Infectious DiseasesCollaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesThe First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Division of Hepatobiliary and Pancreatic Surgery Department of SurgeryThe First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

Liver disease,a major health concern worldwide,is a serious and progressive ***,we not only established a mouse model of DEN+CCl4-induced primary liver disease but also collected clinical human samples to investigate longitudinal alterations in the gut *** liver disease advanced,gut integrity was disrupted,and the mycobiota was disturbed in the mouse *** metabolites associated with hepatocellular carcinoma(HCC)differed from those associated with the cirrhotic phase as follows:levels of stercobilin and aflatoxin B1 dialcohol were reduced,while levels of triterpenoids,bafilomycin A1,and DHEA were increased in the HCC *** abundance of the phylum Chytridiomycota increased as the chronic liver disease progressed and was then replaced by the phylum Ascomycota in *** on the results from clinical human samples,the genus Candida(Ascomycota)(in humans)and the genus Kazachstania(Ascomycota)(in mice)occupied a dominant position in the HCC group,while other fungi were *** increased abundance of *** and depletion of *** may be hallmarks of the progression of liver cirrhosis to early ***,the administration of *** and *** in the LC-HCC progression could accelerate or retard the progression of ***,gut fungi have the potential to serve as a noninvasive clinical biomarker and even a treatment method.

关键词： gut mycobiome liver disease longitudinal studies hepatocarcinogenesis fungal biomarker

Characteristics of the lower layer of sandstorms in the Minqin desert-oasis zone

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Science China Earth Sciences 2011年第5期54卷 703-710页

作者： ZHAO Ming ZHAN KeJie YANG ZiHui FANG ErTian QIU GuoYu wang qiangqiang ZHANG YinChang GUO ShuJiang LI AiDe ZHANG JingChun Gansu Minqin National Station for Desert Steppe Ecosystem Studies Wuwei 733000 China Gansu Desert Control Research Institute Wuwei 733000 China Key Laboratory for Urban Habitat Environmental Science and Technology School of Environment and Energy Peking University Shenzhen Graduate School Shenzhen 518055 China

By measuring the sand-dust flux,vertical deposition,and the wind velocity throughout 19 sandstorms in the Minqin region,we quantitatively analyzed the horizontal distribution and vertical variation in sandstorm characteristics under different land cover *** effect of different land cover on mitigating sandstorms was also *** results indicated that,in the surface layer ranging from 0-50 m,the intensity of sand-dust horizontal flux and concentration of sand-dust decreased with the increase of the height in the desert and the edge of oasis,whereas the two physical quantities increased slightly with the increase of the height in the *** two physical quantities obey power function well under all three cover ***,in the desert and at the edge of oasis,the sand-dust vertical deposition decreased with the increase of the *** a partial unimodal distribution at the oasis site and the maximum deposition occurred at the height of 9 m,which corresponds to the middle height of farmland protection *** annual flux that passed through a section of 1 m in width and 50 m in height was 9169 kg in the desert,5318 kg at the edge of oasis,and 2345 kg in the *** the annual fluxes at the edge of oasis and in the oasis are 42% and 74% less,respectively,than that in the *** implies that the wind break forest significantly reduced the intensity of sandstorms.

关键词： Minqin the lower layer sand-dust horizontal flux vertical deposition

Feature Analysis of the Atmospheric Particulate Pollutants (PM_(10) and PM_(2.5)) in Wenzhou City

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Meteorological and Environmental Research 2013年第4期4卷 37-41页

作者： Yuequn Song Shufan Ye qiangqiang wang Wenzhou Environmental Protection Design Scientific Institute

[ Objective] The research aimed to analyze characteristics of the atmospheric particulate pollutants （ PMlo and PM2.s） in Wenzhou City. [Method] We analyzed interannual change rule of the dust haze in Wenzhou during 1978 -2008. Moreover, we respectively set monitoring points in urban district, industrial park and beauty spot of Wenzhou in summer and winter of 2010. Element, ion and polycyclic aromatic hydrocarbon com- positions and morphology of the particulate matter were analyzed. [ Result] Dust haze in Wenzhou City mainly appeared in winter and spring, which was related to local meteorological condition. In summer and winter, both PMlo and PM2.s concentrations presented the characteristic of industrial park 〉 commercial area 〉 beauty spot. Chain-like particle aggregates and ultrafine particles were main composition of the atmospheric particulate matter in Wenzhou. Contribution rate of the spherical particle amount was smaller than metropolis, which was related to local industry and traffic. Fe element had the most content in particulate matter. Mass concentration was mainly composed of 6 elements, such as Na, Si, S, K, Ca and Fe. Total concentration of the six elements occupied 70% -80% of the 16 elements. SO^- and NH4＊ in particulate matter were higher. They were mainly from human activity. Main compositions of the polycyclic aromatic hydrocarbon were naphthalene, anthracene, benzo （b） fluoranthene, indeno （1,2, 3-cd） pyrene and benzo （g, h, i） perylene, which was related to abrupt increase of the motor vehicle. [ Condusion] The research provided scientific basis and technology support for controlling atmospheric particulate matter pollution in Wenzhou City by government and related department.

关键词： Atmospheric particulate pollutants PM10 PM2.5 Feature analysis China

Global Warming:Increases in the Instability of Climate in Minqin Desert Area

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Meteorological and Environmental Research 2016年第6期7卷 1-7,12页

作者： Zhang Dabiao Chang Zhaofeng wang Dawei Han Fugui Duan Xiaofeng wang qiangqiang Zhang Jianhui Gansu Desert Control Research Institute Lanzhou 730070 China

The instability of climate in Minqin desert area during the process of global warming was analyzed based on meteorological data during 1961-2013. The results show that the instability of monthly average temperature in January and April increased. Isothermal date in February was 10.36 d earlier from 1961 to 2013. The instability of extreme maximum temperature in December and January enhanced. The instability of extreme minimum temperature in July increased. The coefficient of variation of extreme minimum temperature in May was up to 287.3%. The instability of average precipitation in January enhanced. At the same time,the stability of annual average precipitation increased. The stability of climate is more worthy of attention.

关键词： Global warming Desert climate Instability Minqin China

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石膏颗粒接触试验研究

同济大学学报（自然科学版） 2016年第1期44卷 67-72页

作者：周健张津王强强同济大学土木工程学院上海200092 同济大学岩土及地下工程教育部重点实验室上海200092 上海申元岩土工程有限公司上海200040

利用岩石双轴流变试验仪,研究了石膏试件在单轴压缩和颗粒接触条件下的力学特性和破坏模式.结果表明:圆柱单轴压缩试件破坏模式为均匀受力下的一次性剪切破坏,球形颗粒接触试件破坏模式为应力集中下的颗粒破碎多次破坏;在利用离散元模... 详细信息

利用岩石双轴流变试验仪,研究了石膏试件在单轴压缩和颗粒接触条件下的力学特性和破坏模式.结果表明:圆柱单轴压缩试件破坏模式为均匀受力下的一次性剪切破坏,球形颗粒接触试件破坏模式为应力集中下的颗粒破碎多次破坏;在利用离散元模型进行模拟时,同种材料单轴压缩试验的细观参数与颗粒接触试验的细观参数相差较大,不同的受力情况需要分别进行标定.

关键词：石膏颗粒接触试验破坏模式离散元

Particle Size of Barchan Dune in Hexi Desert Area and Its Relationship with Wind Speed

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Animal Husbandry and Feed Science 2016年第4期8卷 239-245页

作者： Chang Zhaofeng Han Shenghui Tang Jinnian wang Qi Zhang Dekui Zhang Jianhui wang qiangqiang Gansu Desert Control Research Institute Lanzhou 730070 China

[ Objective ] The paper was to study the particle size characteristics of barchan dune and its formation mechanism in Hexi desert area d Gansu. [ Method] Through particle size measurement and wind speed flow field observation d dune, the particle size differences of various sampling plots and various parts of dune were analyzed using analysis of variance, and the relationship between particle size and wind speed was analyzed using correlation coefficient method. [ Result] （ 1 ） Barehan dune and barehan chains in Hexi desert area of Gansu were mainly consisted of fine sands and medium sands at the depth of 0 -5 cm： the sand particle in Gulang desert area was fine, which had significant difference with that in Jinchang, Linze, Jinta and Minqin desert areas. （2） Medium sands gradually increased from the bottom of windward slope to the dune peak in both barchan dune and barchan chain. On the windward slope of barehan dune, fine sands gradual- ly increased from the middle to both sides, while coarse sands and medium sands gradually decreased. On the windward slope of barehan chain, fine sands first de- creased then increased from the middle to NE side, but first increased then decreased from the middle to SW side. （3） In terma of particle size, there were great variations between fine sands and coarse sands ; for dune parts, there were great variations between dune peak and leewant slope toe; for dune types, the variation of fine sands in various parts of barchan chain was greater than that of barchan dune, while differentiation degree of medium sands and fine sands was greater than that of barchan dune. The particle size of fine sands was positively correlated with wind speed, and that of medium sands was negatively correlated with wind speed. [ Conclusion] The formation environment of particle size of berehan dune mainly included sand source and dynmnic source, and wind speed was the dynamic source for particle size distribution of barchan dune.

关键词： Barchan dune Barehan chain Particle size Wind speed Heixi desert area of Gansu

Stability and Ecological Effects of Main Plant Communities in Minqin Desert Area

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Animal Husbandry and Feed Science 2015年第3期7卷 191-196页

作者： Chang Zhaofeng Duan Xiaofeng Han Fugui Zhong Shengnian wang qiangqiang Zhang Jianhui Gansu Desert Control Research Institute Minqin National Station for Desert Steppe Ecosystem Studies

[ Objective ] To elucidate the change trend in stability and ecological effects of plant communities in desert along with global wanning. [ Method ] The data of site-specific observation on five main plant communities at ten plots in Minqin desert area were used to analyze the stability and ecological effects of desert plant communities by using two indicators vegetation coverage and projective cover degree. [ Results ] The vegetation coverage of Artemisia arenaria and Ephedra przewalskii, and the projective cover degree of A. arenaria and man-made Haloxylon ammodendron forest decreased remarkably; and the vegetation coverage of Ni- traria tangutorum was also decreased to some extent. [ Conduslon] （1） The plant communities with poor vegetation coverage gives a relatively strong stability, while that with high vegetation coverage has a relatively poor stability; （2） the yearly precipitation is the determinant of vegetation coverage and projective cover deglee; （3） the ecological function is found to be most remarkable in per unit area N. tangutorum, followed by E. przewalskii and N. tangutorum ＋H. ammodendron, and least in per unit area A. Arenaria. The vegetation is sparse in desert and plant branches does not distribute regularly, thus the crown-based vegetation coverage can not reflect the actual surface coverage.

关键词： Plant communities Stability Ecological effects Minqin desert area