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space Weather Service for Chinese space science Satellites

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空间科学学报 2018年第5期38卷 781-787页

作者： LIU Siqing ZHONG Qiuzhen GONG Jiancun SHI Liqin CHEN Dong MIAO Juan CAI Yanxia BAI Meng MA Wenzhen LI Zhitao LIU Fanghua CHEN Yanhong National space science Center Chinese Academy of Sciences Beijing 100190 University of Chinese Academy of sciences Beijing 100049

Strategic Priority Research Program on space science has gained remarkable achievements. space Environment Prediction Center(SEPC) affiliated with the National space science Center(NSSC) has been providing space weather services and helps secure space missions. Presently, SEPC is capable to offer a variety of space weather services covering many phases of space science missions including planning, design, launch,and orbital operation. The service packages consist of space weather forecasts, warnings, and effect analysis that can be utilized to avoid potential space weather hazard or reduce the damage caused by space storms,space radiation exposure for example. Extensive solar storms that occurred over Chinese Ghost Festival(CGF)in September 2017 led to a large enhancement of the solar energetic particle flux at 1 AU, which affected the near Earth radiation environment and brought great threat to orbiting satellites. Based on the space weather service by SEPC, satellite ground support groups collaborating with the space Tracking, Telemetering and Command system(TT&C) team were able to take immediate measures to react to the CGF solar storm event.

关键词：空间天气预报科学卫星服务中国空间科学空间环境暴风雨科学中心

Machine learning and numerical investigation on drag coefficient of arbitrary polygonal particles

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international Journal of Mechanical System Dynamics 2024年第3期4卷 317-330页

作者： Haonan Xiang Cheng Cheng Pei Zhang Genghui Jiang School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjingChina School of Engineering Westlake UniversityHangzhouChina

The drag coefficient,as the most important parameter that characterizes particle dynamics in flows,has been the focus of a large number of *** good predictability is achieved for simple shapes,it is still challenging to accurately predict drag coefficient of complex-shaped particles even under moderate Reynolds number(Re).The problem is that the small-scale shape details of particles can still have considerable impact on the drag coefficient,but these geometrical details cannot be described by single shape *** address this challenge,we leverage modern deep-learning method's ability for pattern recognition,take multiple shape factors as input to better characterize particle-shape details,and use the drag coefficient as *** obtain a high-precision data set,the discrete element method coupled with an improved velocity interpolation scheme of the lattice Boltzmann method is used to simulate and analyze the sedimentation dynamics of polygonal *** different machine-learning models for predicting the drag coefficient are developed and *** results show that our model can well predict the drag coefficient with an average error of less than 5%for *** findings suggest that data-driven models can be an attractive option for the drag-coefficient prediction for particles with complex shapes.

关键词： drag coefficient arbitrary polygonal particle shape factor DEM–LBM machine Learning

Electron transport properties of three-dimensional topological insulators

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Frontiers of physics 2012年第2期7卷 165-174页

作者： Yong-qing Li (1) Ke-hui Wu (1) Jun-ren Shi (2) Xin-cheng Xie (1) (2) 1. institute of Physics Chinese Academy of Sciences Beijing 100190 China2. International Center for Quantum Materials Peking University Beijing 100871 China

We review experimental advances in the study of the electron transport in three-dimensional topo- logical insulators with emphasis on experiments that attempted to identify the surface transport. Recent results on transport properties of topological insulator thin films will be discussed in the context of weak antilocalization and electron-electron interactions. Current status of gate-voltage control of the chemical potential in topological insulators will also be described.

关键词： topological insulator electron transport localization electron-electron interaction,spin-orbit coupling

A study of the temporal and spatial variations in the suitability of the environment in Chinese cities for tourism and in strategies for optimizing the environment

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international Journal of Digital Earth 2022年第1期15卷 527-552页

作者： Ying Li Shuhui Zhang Jingting Han Yi Zhao Quan Han Liyun Wu Xin Wang Ziyi Qiu Tongqian Zou Cheng Fan China Academy of Culture and Tourism Beijing International Studies UniversityBeijingPeople’s Republic of China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of ScienceBeijingPeople’s Republic of China beijing Boneng Technology Co. LtdBeijingPeople’s Republic of China beijing Qinxing international Cultural Exchange Center BeijingPeople’s Republic of China State Environment Protection Key Laboratory of Satellite Remote Sensing Aerospace Information Research InstituteChinese Academy of SciencesBeijingPeople’s Republic of China

With the aim of guaranteeing the interests and health of tourists,this study comprehensively evaluates the suitability of the environment in different cities in China for tourism by considering the impacts of climate,vegetation and environmental factors on *** Universal Thermal Climate Index(UTCI),total precipitation(PREC),Vegetation Leaf Area Index(LAI),concentration of particulate matter with a diameter of less than 2.5μm(PM2.5),and the downward UV radiation at the surface(UVB)are used as *** addition,the Delphi–AHP–TOPSIS algorithm is introduced and is used for the comprehensive evaluation of the environmental suitability of 684 cities in China for tourism in *** is found that Chinese cities vary greatly in terms of the suitability of their environments for *** the factors that affect the environmental suitability,the LAI is important,with an increase in the LAI generally being *** contrast,an increase in the PM2.5 concentration is a key factor that limits the environmental suitability of an ***,urban landscaping and control of the atmospheric quality are essential and effective ways of improving the suitability of the environment of cities in China for tourists.

关键词： Suitability of tourist environment UTCI Delphi–AHP–TOPSIS decision support

Electronic Structure of the Clusters Containing Oxygen in Ni

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Journal of Materials science & Technology 1996年第6期12卷 427-433页

作者： Tao YU Chongyu WANG and Bing WANG (Central Iron and Steel Research institute, beijing 100081, China)(To whom correspondence should be addressed)( The international Centre for Materials Physics of the Chinese Academy of sciences, Shenyang 110015, China) Central Iron and Steel Research institute Beijing 100081 China international Centre for Materials Physics Chinese Academy of Sciences Shenyang 110015 China

The electronic structure of the clusters containing oxygen, the stacking fault and the complex in the transition metal Ni are calculated by the multiple-scattering Xa method. Energy levels,density of states and transfer of charge are obtained. Based on the calculation and analysis,the influences of impurity oxygen and structure defect on the electronic structure of the clusters are discussed, and it is found that the local Ni-o cluster with the interstitial oxygen is a stable atomic configuration.

关键词： Rev Electronic Structure of the Clusters Containing Oxygen in Ni Wang

Genome-Wide Identification of Tomato (Solanum lycopersicum L.) CKX Gene Family and Expression Analysis in the Callus Tissue under Zeatin Treatment

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Phyton-international Journal of Experimental Botany 2024年第6期93卷 1143-1158页

作者： Zhengfeng Lai Dongmei Lian Shaoping Zhang Yudong Ju Bizhen Lin Yunfa Yao Songhai Wu Jianji Hong Zhou Li Subtropical Agriculture Research institute Fujian Academy of Agricultural SciencesZhangzhou363005China

The cytokinin oxidase/dehydrogenase(CKX)enzyme is essential for controlling theﬂuctuating levels of endogen-ous cytokinin(CK)and has a signiﬁcant impact on different aspects of plant growth and ***-less,there is limited knowledge about CKX genes in tomato(Solanum lycopersicum L.).Here we performed genome-wide identiﬁcation and analysis of nine SlCKX family members in tomatoes using bioinformatics *** results revealed that nine SlCKX genes were unevenly distributed onﬁve chromosomes(Chr.1,Chr.4,Chr.8,Chr.10,and Chr.12).The amino acid length,isoelectric points,and molecular weight of the nine SlCKX proteins ranged from 453 to 553,5.77 to 8.59,and 51.661 to 62.494 kD,*** localization analysis indi-cated that SlCKX2 proteins were located in both the vacuole and cytoplasmic matrix;SlCKX3 and SlCKX5 pro-teins were located in the vacuole;and SlCKX1,4,6,7,8,and 9 proteins were located in the cytoplasmic ***,we observed differences in the gene structures and phylogenetic relationships of SlCKX proteins among different ***1-9 were positioned on two out of the three branches of the CKX phylogenetic tree in the multispecies phylogenetic tree construction,revealing their strong conservation within phylogenetic *** patterns of expression of CKX genes were noticed in callus cultures exposed to varying con-centrations of exogenous ZT,suggesting their roles in speciﬁc developmental and physiological functions in the regeneration *** results may facilitate subsequent functional analysis of SlCKX genes and provide valu-able insights for establishing an efﬁcient regeneration system for tomatoes.

关键词： Tomato SlCKX gene family phylogenetic relationships trans-zeatin expression pattern

Shedding vortex simulation method based on viscous compensation technology research

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Chinese Physics B 2022年第4期31卷 414-425页

作者： Hao Zhou Lei Wang Zhang-Feng Huang Jing-Zhi Ren Department of Mechanics Tianjin UniversityTianjin 300072China science and Technology on space Physics Laboratory China Academy of Launch Vehicle TechnologyBeijing 100076China

Owing to the influence of the viscosity of the flow field,the strength of the shedding vortex decreases gradually in the process of backward ***-scale vortexes constantly break up,forming smaller *** engineering,when numerical simulation of vortex evolution process is carried out,a large grid is needed to be arranged in the area of outflow field far from the boundary layer in order to ensure the calculation *** a result,small scale vortexes at the far end of the flow field cannot be captured by the sparse grid in this region,resulting in the dissipation or even disappearance of *** this paper,the effect of grid scale is quantified and compared with the viscous effect through theoretical *** theoretical relationship between the mesh viscosity and the original viscosity of the flow field is established,and the viscosity term in the turbulence model is *** method proves to be able to effectively improve the intensity of small-scale shedding vortexes at the far end of the flow field under the condition of sparse *** error between the simulation results and the results obtained by using fine mesh is greatly reduced,the calculation time is shortened,and the high-precision and efficient simulation of the flow field is realized.

关键词： shedding vortex viscosity analysis numerical dissipation turbulence models

Synthesis of nanocrystalline NiCrC alloy feedstock powders for thermal spraying by cryogenic ball milling

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international Journal of Minerals,Metallurgy and Materials 2009年第1期16卷 77-83页

作者： Kai Tao Xiang-lin Zhou Hua Cui Han-bin Chen Yong-bing Li Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials science and Engineering University of Science and Technology Beijing Beijing 100083 China

Nanocrystalline NiCrC alloy powders with a qualified particle size distribution for thermal spraying were synthesized using the cryogenic ball milling （cryomilling） method. The morphology, microstructure, size distribution, and phase transformation of the powders were characterized by scanning electron microscopy （SEM）, laser scattering for particle size analysis, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. After cryomilling for 20 h, the average grain size of the as-milled powders approached a constant value of 30 nm by XRD measurement. The average particle size slightly increased from 17.5 to 20.3 μm during the 20-h milling. About 90vol% of the powders satisfied the requirement for thermal spraying with the particle dimension of 10-50 μm, and most of the powders exhibited spherical morphology, which were expected to have good fluidity during thermal spraying. The Cr2O3 phase formed during the cryornilling process as revealed in the XRD spectra, which was expected to enhance the thermal stability of the as-milled powders during the followed thermal spraying or other heat treatment.

关键词： cryomilling nanocrystalline feedstock powder particle size distribution nickel chromium alloy

Formation of the bow shock indentation: MHD simulation results

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Earth and Planetary Physics 2021年第3期5卷 259-269页

作者： BaoHang Qu JianYong Lu Ming Wang HuanZhi Yuan Yue Zhou HanXiao Zhang institute of space Weather School of Math&StatisticsNanjing University of Information Science&TechnologyNanjing 210044China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

Simulation results from a global magnetohydrodynamic(MHD)model are used to examine whether the bow shock has an indentation and characterize its formation conditions,as well as its physical *** bow shock is identified by an increase in plasma density of the solar wind,and the indentation of the bow shock is determined by the shock flaring *** is shown that when the interplanetary magnetic field(IMF)is southward and the Alfvén Mach number(Mα)of solar wind is high(>5),the bow shock indentation can be clearly *** reason is that the outflow region of magnetic reconnection(MR)that occurs in the low latitude area under southward IMF blocks the original flow in the magnetosheath around the magnetopause,forming a high-speed zone and a low-speed zone that are upstream and downstream of each *** structure hinders the surrounding flow in the magnetosheath,and the bow shock behind the structure widens and forms an *** Mαis low,the magnetosheath is thicker and the disturbing effect of the MR outflow region is less *** northward IMF,MR occurs at high latitudes,and the outflow region formed by reconnection does not block the flow inside the magnetosheath,thus the indentation is harder to *** study of the conditions and formation process of the bow shock indentation will help to improve the accuracy of bow shock models.

关键词： indentation of bow shock global MHD simulation interplanetary magnetic field Bz Alfvén Mach number