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Typical atmospheric haze during crop harvest season in northeastern China：A case in the Changchun region

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Journal of Environmental Sciences 2017年第4期29卷 101-113页

作者： Wei Wei Chen Daniel q.Tong Mo Dan Shi Chun Zhang xue Lei Zhang Yue Peng Pan Key Laboratory of Wetland Ecology and Environment Northeast Institute of Geography and Agroecology Chinese Academy of Sciences Changchun 130102 China . Cooperative Institute for Climate & Satellites University of Maryland College Park MD 20740 USA Center for Spatial Information Science and Systems George Mason University Fairfax VA 22030 USA Beijing Municipal Institute of Labor Protection Beijing 100054 China State key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

This study presents the mass concentrations of PM（2.5）,O3,SO2 and NOxat one urban,one suburban and two rural locations in the Changchun region from September 25 to October 272013. Major chemical components of PM（2.5）at the four sites were daily sampled and analyzed. Most of daily concentrations of SO2（7–82 μg/m^3）,O3（27–171 μg/m^3） and NOx（14–213 μg/m^3） were below the limits of the National Ambient Air quality Standard（NAAqS）in China. However,PM（2.5）concentrations（143–168 μg/m^3） were 2-fold higher than *** PM（2.5）concentrations（~ 150 μg/m^3） were measured during the pre-harvest and harvest at the urban site,while PM（2.5）concentrations significantly increased from 250 to400 μg m^（-3） at suburban and rural sites with widespread biomass burning. At all sites,PM（2.5）components were dominated by organic carbon（OC） and followed by soluble component sulfate（SO4^（2-））,ammonium（NH4~＋） and nitrate（NO3^-）. Compared with rural sites,urban site had a higher mineral contribution and lower potassium（K~＋and K） contribution to PM（2.5）.Severe atmospheric haze events that occurred from October 21 to 23 were attributed to strong source emissions（e.g.,biomass burning） and unfavorable air diffusion ***,coal burning originating from winter heating supply beginning on October 18 increased the atmospheric pollutant emissions. For entire crop harvest period,the Positive Matrix Factorization（PMF） analysis indicated five important emission contributors in the Changchun region,as follows： secondary aerosol（39%）,biomass burning（20%）,supply heating（18%）,soil/road dust（14%） and traffic（9%）.

关键词： Aerosol Air quality Agriculture Biomass burning PM(2.5) PMF

Reverse-blocking modular multilevel converter for battery energy storage systems

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 652-662页

作者： Xiaofeng YANg Yao xue Bowei CHEN Yajie MU Zhiqin LIN Trillion q.ZHENg Seiki IgARASHI School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China Fuji Electric Co. Ltd.Tokyo 141-0032Japan

Energy storage systems with multilevel converters play an important role in modern electric power systems with large-scale renewable energy *** paper proposes a reverse-blocking modular multilevel converter for a battery energy storage system(RB-MMCBESS). Besides integrating distributed low-voltage batteries to medium or high voltage grids, with the inherited advantages of traditional MMCs, the RB-MMC-BESS also provides improved DC fault handling capability. This paper analyzes such a new converter configuration and its operating principles. Control algorithms are developed for AC side power control and the balancing of battery state of charge. The blocking mechanism to manage a DC pole-topole fault analyzed in depth. Comprehensive simulation results validate both the feasibility of the RB-MMC-BESS topology and the effectiveness of the control and fault handling strategies.

关键词： Reverse blocking Modular multilevel converter Battery energy storage system SOC control Fault blocking

Cleaning Radio Frequency Interference in Pulsar-Folded Data Based on the Conditional Random Fields with an Adaptive Prior

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Research in Astronomy and Astrophysics 2023年第10期23卷 184-191页

作者： xue Chen J.L.Han W.q.Su Z.L.Yang D.J.Zhou National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory of FAST NAOCChinese Academy of SciencesBeijing 100101China

Radio astronomy observations are frequently impacted by radio frequency interference(RFI).We propose a novel method,named 2σCRF,for cleaning RFI in the folded data of pulsar observations,utilizing a Bayesian-based model called conditional random fields(CRFs).This algorithm minimizes the“energy”of every pixel given an initial *** standard deviations(i.e.,rms values)of the folded pulsar data are utilized as pixels for all subintegrations and ***-RFI data without obvious interference is treated as“background noise,”while RFI-affected data have different classes due to their exceptional rms *** initial labeling can be automated and is adaptive to the actual *** CRF algorithm optimizes the label category for each pixel of the image with the prior initial *** demonstrate the efficacy of the proposed method on pulsar folded data obtained from Five-hundred-meter Aperture Spherical radio Telescope *** can effectively recognize and tag various categories of RFIs,including broadband or narrowband,constant or instantaneous,and even weak RFIs that are unrecognizable in some pixels but picked out based on their *** results are comparable to those obtained via manual labeling but without the need for human intervention,saving time and effort.

关键词： methods:data analysis techniques:image processing (stars:)pulsars:general

Novel Modular Multilevel Converter Against DC Faults for HVDC Applications

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CSEE Journal of Power and Energy Systems 2017年第2期3卷 140-149页

作者： Xiaofeng Yang Yao xue Bowei Chen Zhiqin Lin Trillion q.Zheng Yan Li School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China State Key Laboratory of Operation and Control of Renewable Energy&Storage Systems China Electric Power Research InstituteBeijing 100192China

In view of the DC fault current isolation deficiency for the conventional half-bridge sub-module(HBSM)based modular multilevel converter(MMC),this paper presents an improved MMC *** quasi reverse blocking submodules(qRBSMs)and current limit modules(CLMs)are employed to improve the DC fault handling capability for HVDC *** paper analyzes such a new converter configuration and operation *** the DC pole-to-pole short circuit fault is taken into consideration for further study,as well as the fault current blocking mechanism and quantitative relationship between system electrical stress and key *** validate the feasibility of the proposed topology and fault protection theory,extensive simulation results are *** is concluded that the qRB-MMC can effectively block the fault current under DC fault *** addition,CLMs play an important role in further accelerating fault current ***,qRB-MMC employs the original control and modulation strategies under normal operation conditions;thus,it further reduces the complexity of industry design.

关键词： Current limit module DC faults HVDC transmission modular multilevel converter quasi reverse blocking sub-module

Hypericin enhances β-lactam antibiotics activity by inhibiting sarA expression in methicillinresistant Staphylococcus aureus

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Acta Pharmaceutica Sinica B 2019年第6期9卷 1174-1182页

作者： genzhu Wang Liang Li Xiukun Wang xue Li Youwen Zhang Jie Yu Jiandong Jiang xuefu You Yan q.Xiong Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center TorranceCA 90502USA Beijing Key Laboratory of Antimicrobial Agents Institute of Medicinal BiotechnologyChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050China geffen School of Medicine at UCLA Los AngelesCA 90095USA State Key Laboratory of Bioactive Substances and Function of Natural Medicine Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050China

Bacteremia is a life-threating syndrome often caused by methicillin-resistant Staphylococcus aureus(MRSA).Thus,there is an urgent need to develop novel approaches to successfully treat this *** accessory regulator A(SarA),a global virulence regulator,plays a critical role in pathogenesis andβ-lactam antibiotic resistance in Staphylococcus *** is believed to act as an antibiotic,antidepressant,antiviral and non-specific kinase *** the current study,we investigated the impact of hypericin onβ-lactam antibiotics susceptibility and mechanism(s)of its *** demonstrated that hypericin significantly decreased the minimum inhibitory concentrations ofβ-lactam antibiotics(e.g.,oxacillin,cefazolin and nafcillin),biofilm formation and fibronectin binding in MRSA strain *** addition,hypericin significantly reduced sarA expression,and subsequently decreased mecAy and virulence-related regulators(e.g.,agr RNAIII)and genes(e.g.,fnbA and hla)expression in the studied MRSA ***,the in vitro synergistic effect of hypericin withβ-lactam antibiotic(e.g.,oxacillin)translated into in vivo therapeutic outcome in a murine MRSA bacteremia *** findings suggest that hypericin plays an important role in abrogation ofβ-lactam resistance againstMRSA through sarA inhibition,and may allow us to repurpose the use ofβ-lactam antibiotics,which are normally ineffective in the treatment of MRSA infections(e.g.,oxacillin).

关键词： Hyperiein β-Lactams MRSA Synergistic effect SarA

Prediction and predictability of a catastrophic local extreme precipitation event through cloud-resolving ensemble analysis and forecasting with Doppler radar observations

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Science China Earth Sciences 2016年第1期59卷 518-532页

作者： qIU xue Xing ZHANg Fu qing Anhui Meteorological Observatory Hefei 230031 China Department of Meteorology Pennsylvania State University University Park PA 16802 USA

Local extreme rain usually resulted in disasters such as flash floods and landslides. Upon today, it is still one of the most difficult tasks for operational weather forecast centers to predict those events accurately. In this paper, we simulate an extreme precipitation event with ensemble Kalman filter(En KF) assimilation of Doppler radial-velocity observations, and analyze the uncertainties of the assimilation. The results demonstrate that, without assimilation radar data, neither a single initialization of deterministic forecast nor an ensemble forecast with adding perturbations or multiple physical parameterizations can predict the location of strong precipitation. However, forecast was significantly improved with assimilation of radar data, especially the location of the precipitation. The direct cause of the improvement is the buildup of a deep mesoscale convection system with En KF assimilation of radar data. Under a large scale background favorable for mesoscale convection, efficient perturbations of upstream mid-low level meridional wind and moisture are key factors for the assimilation and forecast. Uncertainty still exists for the forecast of this case due to its limited predictability. Both the difference of large scale initial fields and the difference of analysis obtained from En KF assimilation due to small amplitude of initial perturbations could have critical influences to the event's prediction. Forecast could be improved through more cycles of En KF assimilation. Sensitivity tests also support that more accurate forecasts are expected through improving numerical models and observations.

关键词： En KF Doppler radar data Local extreme rain Predictability

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The Ext-group of Unitary Equivalence Classes of Unital Extensions

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Acta Mathematica Sinica,English Series 2011年第12期27卷 2329-2342页

作者： Yi Feng xue Department of Mathematics East China Normal University Shanghai 200241 P. R. China

Let A be a unital separable nuclear C＊-algebra which belongs to the bootstrap category N and B be a separable stable C＊-algebra. In this paper, we consider the group Ext,（A, B） consisting of the unitary equivalence classes of unital extensions T： A→ q（B）. The relation between Ext,（A, B） and Ext（A, B） is established. Using this relation, we show the half-exactness of Ext,（-, B） and the （UCT） for Ext,（A, B）. Furthermore, under certain conditions, we obtain the half-exactness and Bott periodicity of Extu （A, .）.

关键词： Unital extension multiplier algebra Ext-group quasi-unital ,-homomorphism

Doubled Hecke Algebras and Related quantum Schur Duality

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Algebra Colloquium 2024年第3期31卷 417-428页

作者： Chenliang xue An Zhang School of Mathematical Sciences East China Normal University Shanghai 200241China

We introduce the doubled Hecke algebra,which is an infinite-dimensional algebra generated by two Hecke *** concept originates from the degenerate doubled Hecke algebra in the theory of Schur-Weyl duality related to enhanced reductive algebraic *** study the finite-dimensional natural representation of the doubled Hecke algebra on tensor space and prove that the doubled Hecke algebra forms a duality with the quantum group of Levi type.

关键词： quantum group doubled Hecke algebra quantum q-Schur duality double centralizer

THE EFFECTS OF NEgATIVE BIAS AND FLUX RATIO ON THE PROPERTIES OF TiN THIN FILMS FORMED BY FILTERED CATHODIC ARC PLASMA TECHNIqUE

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 369-374页

作者： Y.J.Zhang P.X.Yan Z.g.Wu W.W.Zhang J.Wang q.J.xue DeparunentofPhysics LanzhouUniversitryLanzhou730000China DeparunentofPhysics LanzhouUniversitryLanzhou730000China／／StateKeyLaboratoryofSolidLubricationInstituteofChemicalPhysicsTheChineseAcademyofSciencesLanzhou730000China StateKeyLaboratoryofSolidLubrication InstituteofChemicalPhysicsTheChineseAcademyofSciencesLanzhou730000China

The filtered cathodic vacuum-arc (FCVA) technique is a supplementary and alterna tive technique with respect to convendtional physical and chemical vapour deposi tion which can remove macro-particles effectively and make the deposition proces s at ambient temperature. In this work, high quality TiN thin films were deposi ted on silicon substrates at low temperature using the improved filtered cathodi c arc plasma (FCAP) technique. AFM, XRD, TEM were employed to characterize the T iN thin films. The effects of the negative substrate bias on the grain size, pre ferred crystalline orientation, surface roughness of TiN thin films were discuss ed.

关键词： TiN filtered cathodic arc plasma preferred orientation