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Circulating Current Suppression for MMC-HVDC Systems with Asymmetric Arm Impedance

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CSEE Journal of Power and Energy Systems 2021年第3期7卷 530-540页

作者： Fujin Deng qian heng Chengkai Liu Yongqing Lyu Qingsong Wang Dan Liu Rongwu Zhu School of Electrical Engi-neering Southeast Universityand Jiangsu Key Laboratory of Smart Grid Technology and EquipmentNanjing 210096China School of Electrical Engineering Southeast UniversityNanjing 210096China State Grid Jiangsu Electric Power CO. LTD.Research InstituteNanjing 211106China Department of Power Electronics Christian-Albrechts-University of KielKiel2D-24142Germany

The modular multilevel converter(MMC)has been a highly promising topology in the high-voltage direct-current(HVDC)transmission area,where each arm of the MMC may consist of hundreds of series-connected submodules and an *** to its parameter inaccuracy,component aging,and so on,the component parameter in different arms of the MMC may be different,which may cause circulating current in the MMC-HVDC transmission system,and result in current deterioration,power losses,and electromagnetic interference,*** this paper,the circulating current suppressing(CCS)in the MMC-HVDC system,due to asymmetric arm impedance,is *** on the mathematical analysis,a method of using an auxiliary circuit is proposed for the MMC to realize the CCS and improve the performance of the MMC-HVDC *** studies are conducted with PSCAD/EMTDC in the HVDC system,which confirms the feasibility of the proposed method.

关键词： Circulating current suppressing control strategy high-voltage direct-current modular multilevel converter

A New Ocean Mixed-Layer Model Coupled into WRF

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Atmospheric and Oceanic Science Letters 2012年第3期5卷 170-175页

作者： WANG Zi-qian duan An-Min The State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmos- pheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

A new mesoscale air-sea coupled model (WRF- OMLM-Noh) was constructed based on the Weather Research and Forecasting (WRF) model and an improved Mellor-Yamada ocean mixed-layer model from Noh and Kim (OMLM-Noh). Through off-line tests and a simulation of a real typhoon, the authors compared the performance of the WRF-OMLM-Noh with another existing ocean mixed-layer coupled model (WRF-OMLM-Pollard). In the off-line tests with Tropical Ocean Global Atmosphere Program's Coupled Ocean Atmosphere Response Experiment (TOGA-COARE) observational data, the results show that OMLM-Noh is better able to simulate sea surface temperature (SST) variational trends than OMLM -Pollard. Moreover, OMLM-Noh can sufficiently reproduce the diurnal cycle of SST. Regarding the typhoon case study, SST cooling due to wind-driven ocean mixing is underestimated in WRF-OMLM-Pollard, which artificially increases the intensity of the typhoon due to more simulated air-sea heat fluxes. Compared to the WRF- OMLM-Pollard, the performance of WRF-OMLM-Noh is superior in terms of both the spatial distribution and temporal variation of SST and air-sea heat fluxes.

关键词： WRF-OMLM-Noh sea surface temperature ocean mixed layer air-sea coupled model

Segregation enabled outstanding combination of mechanical and corrosion properties in a FeCrNi medium entropy alloy manufactured by selective laser melting

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Journal of Materials Science & Technology 2022年第4期99卷 207-214页

作者： heng duan Bin Liu Ao Fu Junyang He Tao Yang C.T.Liu Yong Liu State Key Lab of Powder Metallurgy Central South UniversityChangsha 410083China Max-Planck-Institut für Eisenforschung Max-Planck-βe 1Düsseldorf 40237Germany Department of Materials Science and Engineering City University of Hong KongHong KongChina Department of Mechanical Engineering City University of Hong KongHong KongChina

Selective laser melting(SLM)has the advantage in preparing supersaturated solid solutions due to its unique thermal field and high solidification *** this study,a face-centered cubic single-phase FeCrNi medium entropy alloy(MEA)with an ultrahigh Cr content(~35 at.%)was additively manufactured by *** as-built MEA shows a hierarchical microstructure of coarse columnar grains and submicron dislocation cell structures,where the cell boundaries are probed segregated with Cr and C and decorated with nano *** appearance of these dislocation barriers results in an excellent combination of strength(σ_(0.2)=745 MPa,σ_(UTS)=1007 MPa)and ductility(ε_(f)=31%).The current MEA also shows a superb corrosion resistance with a corrosion current density of 0.06μA cm^(−2) in 3.5 wt.%NaCl solution,which is far lower than that of 316 *** high content of solutioned Cr in the MEA ensures sufficient Cr supply to form an integrated Cr_(2)O_(3) passive film,and the large number of cell boundaries acting as the diffusion channels lead to the fast formation of a stable passive film over the alloy surface.

关键词： Selective laser melting Microsegregation Strength Ductility Corrosion resistance

Active sites and reaction mechanism for N-doped carbocatalysis of phenol removal

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Green Energy & Environment 2020年第4期5卷 444-452页

作者： Mingjie Zhang Chen Han Wenyao Chen Wei Luo Yueqiang Cao Gang qian Xinggui Zhou Xiaoguang duan Shaobin Wang Xuezhi duan State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China WA School of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityPerthWestern Australia 6845Australia School of Chemical Engineering The University of AdelaideAdelaideSouth Australia 5005Australia

Heteroatom-doping of carbocatalysts has been a powerful strategy to remarkably enhance the catalytic ***,the underlying nature of N promotional effects on peroxymonosulfate(PMS)activation for phenol removal is understood by combining kinetics analysis with multiple techniques.A strategy using mixed acid oxidation of carbon nanotube(CNT)followed by NH3 treatment is employed to yield a series of catalysts with different N-doping contents but similar fraction of sp^(2)-hybridized carbon and defective degree,endowing with a chance to discriminate the dominant N-containing active *** multi-sites kinetics analysis suggests the graphitic N-containing sites as the dominant active *** mechanism of the surface-bound reactive species is also discriminated as the dominant reaction *** insights reported here could provide the methodology to fundamentally understand the heteroatom-doping effects of carbocatalysis.

关键词： Phenol removal Carbocatalysis Multi-sites kinetics analysis Graphitic N-Containing sites Surface-bound reactive species

Effect of compound Sophorae decoction in the treatment of ulcerative colitis by tissue extract metabolomics approach

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Journal of Traditional Chinese Medicine 2021年第3期41卷 414-423页

作者： HONG Zongchao CAI Quan duan Xueyun YANG Yanfang WU Hezhen JIANG Nan FAN heng College of Pharmacy Hubei University of Chinese MedicineWuhan 430065China Department of Integrated Traditional Chinese and Western Medicine Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430022China Hubei Provincial Hospital of Traditional Chinese Medicine Wuhan430061China Hubei Province Academy of Traditional Chinese Medicine Wuhan430074China

OBJECTIVE: To investigate how compound Sophorae decoction(CSD) works on rats' models of ulcerative colitis(UC) induced by 2,4,6-trinitrobenzenesulfonic acid solution(TNBS) by metabolomics studies of colon, liver, and kidney tissue ***: Rats with UC induced by TNBS enema were used as models in this study. Metabolic profiles of the three tissues were analyzed and pathway analysis of biomarkers was performed after CSD administration and further integration of metabolic ***: Thirteen biomarkers were screened from colon, liver, and kidney tissue extracts, and the levels of these substances were up-or down-regulated in the model group, but their levels were reversed after CSD administration. These biomarkers were mainly related to Phenylalanine, tyrosine and tryptophan biosynthesis, Phenylalanine metabolism, Glutathione metabolism, Arachidonic acid metabolism, Nicotinate and nicotinamide metabolism,Alanine, aspartate and glutamate ***: CSD could significantly ameliorate the symptoms of UC by regulating multiple metabolic pathways.

关键词： colitis ulcerative metabolomics trinitrobenzenesulfonic acid compound Sophorae decoction

A possible precessing nozzle and the Lense-Thirring effect in blazar 3C 454.3

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Research in Astronomy and Astrophysics 2014年第3期14卷 249-274页

作者： Shan-Jie qian S.Britzen A.Witzel T.P.Krichbaum heng-qian Gan Long Gao National Astronomical Observatories Chinese Academy of Sciences Max-Planck Institt fr Radioastronomie

The kinematics of superluminal components in blazar 3C 454.3 are *** components are included： superluminal knots R1, R2, R3, R4, A, B, C and D（from Britzen et al. 2013） and C4 （from Pauliny-Toth 1998）. We find that their kine-matics derived from VLBI observations can be consistently interpreted in terms of ajet precession scenario with a period of about 14.5 yr. We discuss the model fits oftheir trajectory, distance from the core and apparent velocity. We show that the bulkLorentz factor （in the range 4 to 15） derived for these components does not have anydependence on the phase of the precession （or position angle for ejection）. The Lense-Thirring effect is assumed to interpret the precession of the jet nozzle. The resultsobtained for blazar 3C 454.3 are only suggestive. They are not unique and have yet tobe tested, but they might be useful for understanding the kinematics of superluminalcomponents in blazars and for disentangling different mechanisms and factors.

关键词： radio continuum: galaxies galaxies: jets galaxies: kinematics galaxies: individual (blazar 3C 454.3)

ERK1/2 Activities Are Dispensable for Oocyte Growth but Are Required for Meiotic Maturation and Pronuclear Formation in Mouse

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Journal of Genetics and Genomics 2015年第9期42卷 477-485页

作者： Yin-Li Zhang Xiao-Man Liu Shu-Yan Ji qian-qian Sha Jue Zhang heng-Yu Fan Life Sciences Institute Zhejiang University

Previous studies revealed that extracellular regulated kinase-1 and -2 （ERK1/2） cascade plays pivotal roles in regulating oocyte meiotic cell cycle progression. However, most knowledge about the in vivo function of ERK1/2 in mammalian oocytes was indirectly obtained from analyzing the phenotypes of Mos knockout mice. In this study, we knocked out Erkl and Erk2 in mouse oocytes as early as the primordial follicle stage using the well-characterized Gdp-Cre mouse model, and for the first time directly investigated the in vivo function of ERK1/2 in mouse oocytes. In this novel mouse model, we observed that ERK1/2 activities in oocyte are dispensable for primordial follicle maintenance, activation and follicle growth. Different from the Mos null oocytes, the ERK1/2-deleted oocytes had well-assembled spindles at metaphase I （MI）, extruded polar body-I （PB1） with normal sizes, and did not undergo a full parthenogenetic activation characterized for pronuclear formation. However, the ovulated ERK1/2-deleted oocytes had poorly-assembled metaphase II （MII） spindles, spontaneously released polar body-2 （PB2）, and were arrested at another metaphase called metaphase III （MIII）. In addition, ERK1/2 deletion prevented male pronuclear formation after fertilization, and caused female infertility. In conclusion, these results indicate that ERK1/2 activities are required for not only MII-arrest maintenance, but also efficient pronuclear formation in mouse oocytes.

关键词： Oocyte Female reproduction Meiosis ERK1/2 Fertilization

The Discovery of ～310 Ma Back-Arc Basin Basalt in the West Junggar,Xinjiang,NW China and its Geological Significance

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Acta Geologica Sinica(English Edition) 2019年第2期93卷 496-498页

作者： ZHI qian LI Yongjun YANG Gaoxue duan Fenghao TONG Lili School of Earth Science and Resources Chang'an University Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits MNR

Objective Mafic magmas can form in different tectonic settings with various geochemical characteristics depending on their mantle sources. Basalts generated in back-arc basins provide valuable perspectives on mantle s... 详细信息

关键词： Ma Back-Arc West Junggar Xinjiang Geological Significance

Modal Parameter Identification Method of Jacket Platform Structure Based on AFDD and Optimized FBFFT

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China Ocean Engineering 2023年第3期37卷 393-407页

作者： LENG Jian-cheng MA Jin-yong FAN Zong-heng qian Wan-dong FENG Hui-yu School of Mechanical Science and Engineering Northeast Petroleum UniversityDaqing 163318China

Offshore platforms are susceptible to structural damage due to prolonged exposure to random loads,such as wind,waves,and *** is particularly true for platforms that have been in service for an extended *** the modal parameters of offshore platforms is crucial for damage diagno sis,as it serves as a prerequisite and foundation for the ***,it holds great significance to prioritize the identification of these *** at the shortcomings of the traditional Fast Bayesian Fast Fourier Transform(FBFFT) method,this paper proposes a modal parameter identification method based on Automatic Frequency Domain Decomposition(AFDD) and optimized *** introducing the AFDD method and Powell optimization algorithm,this method can automatically identify the initial value of natural frequency and solve the objective function efficiently and *** order to verify the feasibility and effectiveness of the proposed method,it is used to identify the modal parameters of the IASC-ASCE benchmark model and the j acket platform structure model,and the Most Probable Value(MPV) of the modal parameters and their respective posterior uncertainties are successfully *** identification results of the IASC-ASCE benc hmark model are compared with the identification re sults of the MODE-ID method,which verifies the effectivene ss and accuracy of the proposed method for identifying modal *** provides a simple and feasible method for quantifying the influence of uncertain factors such as environmental parameters on the identification results,and also provide s a reference for modal parameter identification of other large structures.

关键词： jacket platform uncertain modal parameter identification FBFFT method environmental excitation AFDD method Powell optimization