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Daytime lidar measurements of the sodium layer in China

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Science China Earth Sciences 2016年第8期59卷 1707-1708页

作者： liu xiao XU JiYao School of Mathematics and Information Science Henan Normal University State Key Laboratory of Space Weather National Space Science Center Chinese Academy of Sciences

Metal layers are formed owing to the deposition of metal species, such as, Na, Fe, Ma, Si, Ca, and K, in the mesosphere and lower thermosphere region. The metal species come from the meteor ablations when meteors enter into the atmosphere （Plane, 1991）. Among these species, Na can be easily detected by sodium lidar since it has enough abundance and large backward scattering cross-section. On the other hand, the chemical lifetime of the sodium layer is longer than one day in the main sodium layer （85-100 km） and thus can be employed as a dynamical tracer for atmospheric perturbations （Xu et al., 2003）.

关键词： lidar backward lifetime enough abundance longer

Clinical characteristics and management of coexistent cardiomyopathy in patients with bicuspid aortic valve

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Journal of Geriatric Cardiology 2023年第3期20卷 205-213页

作者： di ZHANG Yi-Ting LU Ze-Min ZHOU Yu-xiao HU Xin-Chang liu Yi QU Ya-Xin liu Xian-Liang ZHOU Department of Cardiology Fuwai HospitalNational Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Emergency and Critical Care Center Fuwai HospitalNational Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina

BACKGROUND Bicuspid aortic valve(BAV)is the most common congenital heart ***,the prevalence,clinical characteristics,and current management of BAV associated with inherited cardiomyopathy,including hypertrophic cardiomy-opathy(HCM),dilated cardiomyopathy(DCM),and left ventricular noncompaction(LVNC)have not been well *** Consecutive patients diagnosed with BAV at a large tertiary cardiovascular referral center between 2009 and 2018 were retrospectively assessed for HCM,DCM,and LVNC based on clinical and echocardiographic *** with coexist-ent conditions were investigated *** Of 3533 patients with BAV screened,57(1.6%)had concomitant *** was combined with HCM in 30 of these patients,with DCM in 19,and with LVNC in ***-six patients(80.7%)were male,and the mean age at first dia-gnosis was 47 years for BAV with HCM,49 years for BAV with DCM,and 35 years for BAV with *** failure and aortic valve dysfunction were common in these patients,and the prevalence of coexisting aortopathy was 43.3%,26.3%and 25.0%,re-spectively,for BAV with HCM,DCM and *** the index hospitalization,24 of the 57 patients(42.1%)underwent sur-gery,16(28%)underwent aortic valve and/or aortic surgery,and 16 of the 30 patients with HCM had a Morrow *** were no deaths or other major adverse cardiovascular *** The prevalence of inherited cardiomyopathy was higher in our patients with BAV than in the general *** and heart failure were common,with almost half of patients requiring surgery at diagnosis.

关键词： patients cardiomyopathy aortic

SOLVING OPTIMIZATION PROBLEMS OVER THE STIEFEL MANIFOLD BY SMOOTH EXACT PENALTY FUNCTIONS

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Journal of Computational Mathematics 2024年第5期42卷 1246-1276页

作者： Nachuan xiao Xin liu The Institute of Operations Research and Analytics National University of SingaporeSingapore State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of Sciencesand University of Chinese Academy of SciencesChina

In this paper,we present a novel penalty model called ExPen for optimization over the Stiefel *** from existing penalty functions for orthogonality constraints,ExPen adopts a smooth penalty function without using any first-order derivative of the objective *** show that all the first-order stationary points of ExPen with a sufficiently large penalty parameter are either feasible,namely,are the first-order stationary points of the original optimization problem,or far from the Stiefel ***,the original problem and ExPen share the same second-order stationary ***,the exact gradient and Hessian of ExPen are easy to *** a consequence,abundant algorithm resources in unconstrained optimization can be applied straightforwardly to solve ExPen.

关键词： Orthogonality constraint Stiefel manifold Penalty function

Avian influenza A(H7N9)virus:from low pathogenic to highly pathogenic

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Frontiers of Medicine 2021年第4期15卷 507-527页

作者： William J.liu Haixia xiao Lianpan Dai di liu Jianjun Chen xiaopeng Qi Yuhai Bi Yi Shi George F.Gao Yingxia liu Shenzhen Key Laboratory of Pathogen and Immunity Shenzhen Third People’s HospitalShenzhen518114China National Institute for Viral disease Control and Prevention Chinese Center for Disease Control and PreventionBeijing102206China Laboratory of Protein Engineering and Vaccines Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences(CAS)Tianjin300308China CAS Key Laboratory of Pathogenic Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing100101China CAS Key Laboratory of Special Pathogens and Biosafety Chinese Academy of SciencesWuhan430071China National Virus Resource Center Chinese Academy of SciencesWuhan430071China University of Chinese Academy Sciences Beijing100049China Center for Influenza Research and Early Warning Chinese Academy of SciencesBeijing100101China Chinese Center for disease Control and Prevention Beijing102206China

OriginalTranslation The avian influenza A(H7N9)virus is a zoonotic virus that is closely associated with live poultry *** has caused infections in humans in China since *** waves of the H7N9 influenza epidemic occurred in China between March 2013 and September 2017.H7N9 with low-pathogenicity dominated in the first four waves,whereas highly pathogenic H7N9 influenza emerged in poultry and spread to humans during the fifth wave,causing wide *** and officials from China and other countries responded quickly,controlled the epidemic well thus far,and characterized the virus by using new technologies and surveillance tools that were made possible by their preparedness ***,we review the characteristics of the H7N9 viruses that were identified while controlling the spread of the *** was summarized and discussed from the perspectives of molecular epidemiology,clinical features,virulence and pathogenesis,receptor binding,T-cell responses,monoclonal antibody development,vaccine development,and disease *** data provide tools for minimizing the future threat of H7N9 and other emerging and re-emerging viruses,such as SARS-CoV-2.

关键词： H7N9 HPAIV clinical features epidemiology hemagglutinin immunity pathogenesis vaccine

Core engineering of paired core-shell silver nanoclusters

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Science China Chemistry 2021年第12期64卷 2118-2124页

作者： Shan-Shan Zhang Rui-Chen liu xiao-Chen Zhang Lei Feng Qing-Wang Xue Zhi-Yong Gao Chen-Ho Tung di Sun Key Lab of Colloid and Interface Chemistry Ministry of EducationSchool of Chemistry and Chemical EngineeringState Key Laboratory of Crystal MaterialsShandong UniversityJinan250100China School of Chemistry and Chemical Engineering Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine ChemicalsKey Laboratory of Green Chemical Media and ReactionsMinistry of EducationHenan Normal UniversityXinxiang453007China Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology School of Chemistry and Chemical EngineeringLiaocheng UniversityLiaocheng252000China

Unlike the facile modulation of surface structure through protecting ligands,the core shielded by outer shell of silver nanoclusters is still hard to be *** effects may seep into the incipient growth of silver ***,the comparable cases to validate such hypothesis are currently ***,we shed light on two core-shell silver nanoclusters,Ag_(7)S_(6)@Ag_(48)(SD/Ag55b,SD=Sundi)and Ag_(6)S_(6)@Ag_(48)(SD/Ag54b),differing in only one silver atom in the core which varies from a pentagon-bipyramidal Ag_(7)to an octahedral Ag_(6)while keeping the Ag_(48)shielding shell almost the *** no direct bonding between alkynes and silver core is observed in them,we propose that the ligand effect still exerts profound influences on the size and geometry of silver *** solution behaviours and complete ligand-exchange reaction of SD/Ag55b in CH_(2)Cl_(2)are investigated using electrospray ionization mass *** to more and stronger argentophilic interactions,SD/Ag55b exhibits room-temperature phosphorescence with a 40 nm red-shift compared to that of SD/Ag54b in CH_(2)Cl_(2).This work not only presents effective fabrication of silver nanoclusters via synergism of dithiophosphate and alkyne ligands,but also provides us a pair of comparable examples to understand substitution group effect of protecting ligand on the core structures and properties.

关键词： silver nanocluster core engineering argentophilic interactions red-shifted phosphorescence dynamic ligand exchange

A MULTISCALE MODELING APPROACH INCORPORATING ARIMA AND ANNS FOR FINANCIAL MARKET VOLATILITY FORECASTING

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Journal of Systems Science & Complexity 2014年第1期27卷 225-236页

作者： xiao Yi xiao Jin liu John WANG Shouyang School of Information Management Central China Normal University Wuhan 430079 China. Business School Sichuan Universil~y Chengdu 610064 China. Center for Transport Trade and Financial Studies City University of Hong Kong Hong Kong China. Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China.

The financial market volatility forecasting is regarded as a challenging task because of irreg ularity, high fluctuation, and noise. In this study, a multiscale ensemble forecasting model is proposed. The original financial series are decomposed firstly different scale components （i.e., approximation and details） using the maximum overlap discrete wavelet transform （MODWT）. The approximation is pre- dicted by a hybrid forecasting model that combines autoregressive integrated moving average （ARIMA） with feedforward neural network （FNN）. ARIMA model is used to generate a linear forecast, and then FNN is developed as a tool for nonlinear pattern recognition to correct the estimation error in ARIMA forecast. Moreover, details are predicted by Elman neural networks. Three weekly exchange rates data are collected to establish and validate the forecasting model. Empirical results demonstrate consistent better performance of the proposed approach.

关键词： ARIMA model financial market volatility forecasting multiscale modeling approach,neural network wavelet transform.

LPI radar signal detection based on radial integration of Choi-Williams time-frequency image

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Journal of Systems Engineering and Electronics 2015年第5期26卷 973-981页

作者： Yongjian liu Peng xiao Hongchao Wu Weihua xiao Science and Technology on Complex Aviation Systems Simulation Laboratory Aviation University of Air Force

This paper mainly revolves the time-frequency image of low probability of intercept(LPI) radar signals and carries out research work on image features selection and extraction and recognition. Since Choi-Williams distribution(CWD) uses the exponential kernel of bilinear generalized class of time-frequency distribution, it has an excellent time-frequency aggregation. And it is suitable for detecting LPI radar signals in a low signal-to-noise ratio(SNR) condition. A radial integration method based on the integral rotating factor is proposed to detect LPI radar signals when the signals’ time-frequency image is obtained. First, the digital image processing method is used to preprocess the LPI radar signals’ time-frequency images after CWD transformation; then, the radial integration method based on the integral rotating factor is used to detect LPI radar signals in the binary images. The analytic results of real data show that the method has a good performance on detecting LPI radar signals in a low SNR condition. Additionally,the method is simple and takes less logic resources and has the potential of real-time detection of LPI radar signals.

关键词： low probability of intercept(LPI) integral rotating factor signal detection image processing

Co_(3)O_(4)/stainless steel catalyst with synergistic effect of oxygen vacancies and phosphorus doping for overall water splitting

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Tungsten 2023年第1期5卷 100-108页

作者： xiao-xiao Li xiao-Chao liu Chao liu Jin-Ming Zeng xiao-Peng Qi College of Rare Earth Jiangxi University of Science and TechnologyGanzhou 341000China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China

The electrolysis of water into hydrogen and oxygen provides an effective means of storing electrical energy *** current challenge is to design an optimal catalyst that exhibits low overpotentials,long-term stability,universal availability,and only uses inexpensive ***,a Co3O4nanoflower/stainless steel(P-Ov-CO_(3)O_(4)/SS) catalyst with both oxygen vacancies(Ovs) and phosphorus doping was perfectly prepared via a simple three-step *** Ovs promoted charge transfer and accelerated the electrocatalysis,while P finely tuned the surface charge *** resulted in numerous active sites for catalysis,and the synergistic effect of phosphorus doping and oxygen vacancies was finely *** resultant electrocatalyst exhibited low hydrogen evolution overpotentials of 118 mV(-10 mA·cm^(-2)) and 242(-200 mA·cm^(-2)),as well as oxygen evolution overpotentials of 327 mV(100 mA·cm^(-2)) and 370 mV(200 mA·cm^(-2)),owing to the excellent synergistic effect of the Ovs and low-temperature ***,P-Ov-Co_(3)O_(4)/SS//P-Ov-Co_(3)O_(4)/SS exhibited a low water splitting voltage of 1.681 V at 20 *** findings will enable the synthesis of novel high-performance electrocatalysts for overall water splitting.

关键词： Oxygen vacancy Phosphorus doping P-Ov-Co_(3)O_(4)/SS Overall water splitting

Machine learning-based fast frequency response control for a VSC-HVDC system

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 688-697页

作者： Kaiqi Sun Huangqing xiao Shengyuan liu Yilu liu University of Tennessee KnoxvilleTN 37996USA University of Tennessee KnoxvilleTN 37996USA and also with the Oak Ridge National LaboratoryOak RidgeTN 37831USA

HVDC system can realize a very fast frequency response to the disturbed system under a contingency because its active power control is decoupled from the frequency ***,most of existing HVDC frequency control strategies are coupled with system primary frequency control and secondary frequency *** the traditional system frequency control is dominated by the thermal generators,the advantage of the fast response of the HVDC system is not made fully *** development of a frequency response estimation based on a machine learning algorithm provides another approach to improve the frequency response capability of the HVDC *** from other frequency deviation tracking strategies,a machine learning based HVDC frequency response control can directly increase the power flow of a HVDC system by estimation of the system generator or load *** this paper,a fast frequency response control using a HVDC system for a large power system disturbance based on the multivariate random forest regression(MRFR)algorithm is *** simulation is carried out with an integrated power system model based on the North American *** simulation results indicate that the proposed MRFR based frequency response control can significantly improve the frequency low point during an event,while stabilizing the frequency in advance.

关键词： Frequency response control multivariate random forest regression VSC-HVDC system