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Application of Holdridge life-zone model based on the terrain factor in Xinjiang Automous Region

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Journal of Environmental Sciences 2005年第6期17卷 1042-1046页

作者： NI Yong-ming OUYANG Zhi-yun WANG xiao-ke Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

This study improved the application of the Holdridge life-zone model to simulate the distribution of desert vegetation in China which gives statistics to support eco-recovery and ecosystem reconstruction in desert area. This study classified the desert vegetation into four types：（1） LAD： little arbor desert; （2） SD： shrub desert：（3） HLHSD： half-shrub, little half-shrub desert; （4） LHSCD： little halfshrub cushion desert. Based on the classification of Xinjiang desert vegetation, the classical Holdridge life-zone model was used to simulate Xinjiang desert vegetation＇s distribution and compare the Kappa coefficient result of the model with table of accuracy represented by Kappa values. The Kappa value of the model was only 0.19, it means the simulation result was poor. To improve the life-zone model application to Xinjiang desert vegetation type, a set of plot standards for terrain factors was developed by using the plot standard as the reclassification criterion to climate sub-regime. Then the desert vegetation in Xinjiang was simulated. The average Kappa value of the second simulation to the respective climate regime was 0.45. The Kappa value of final modeling result was 0.64, which is the better value. The modification of the model made it in more application region. In the end, the model＇ s ecological relevance to the Xinjiang desert vegetation types was studied.

关键词： Xinjiang desert vegetation types Holdridge life-zone terrain climate regime

Characteristics of motorized spindle supported by active magnetic bearings

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Chinese Journal of Aeronautics 2014年第6期27卷 1619-1624页

作者： Xie Zhenyu Yu Kun Wen Liantang Wang xiao Zhou Hongkai Department of Design Engineering Nanjing University of Aeronautics and Astronautics Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Jiangxi Zhonghang Optics Equipment Co. Ltd.

A motorized spindle supported by active magnetic bearings（AMBs） is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.

关键词： Dynamic characteristics Finite element analysis Loss Magnetic bearings Modal analysis Spindle design

Fabrication of ultrafine ZnFe2O4 nanoparticles for efficient photocatalytic reduction CO2 under visible light illumination

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Journal of Materials Science & Technology 2018年第12期34卷 2331-2336页

作者： Jun xiao Weiyi Yang Shuang Gao Caixia Sun Qi Li Environment Functional Materials Division Shenyang National Laboratory for Materials ScienceInstitute of Metal ResearchChinese Academy of SciencesShenyong 110016China University ofChineseAcademy of Sciences Beijing 100049China Division of Energy and Environment Graduate School of ShenzhenTsinghua UniversityShenzhen 518055China Key Laboratory of New Metallic Functional Materials and Advanced Surface Engineering in Universities of Shandong Qingdao Binhai UniversityQingdao 266555China School of Mechanical and Electronic Engineering Qingdao Binhai UniversityQingdao 266555China

A one-pot, solvent-thermal process was used to create the ultrafine ZnFe2O4nanoparticles *** the solvent-thermal process, the in situ self-forming NaCl not only served as a "cage" to confine the ion diffusion, but also acted as a microreactor for nanocrystallite growth. An average particle size of ～10 nm and a high-specific surface area of～112.9 m2/g were observed for the ultrafine ZnFe2O4nanoparticles Owing to the synergistic effect of ultrafine particle size, the full utilization of the visible light region and high conduction band(CB) position, ultrafine ZnFe2O4photocatalyst displayed an efficient photocatalytic CO2reduction under visible light illumination. Besides, the ultrafine ZnFe2O4photocatalyst showed high production selectivity for CH3CHO and C2H5OH generation in aqueous CO2/NaHCO3solution. This work may provide a new idea for the synthesis of new high-efficiency photocatalysts.

关键词： Ultrafine nanoparticles Photocatalytic CO_2 reduction Visible light ZnFe_2O_4 photocatalyst In situ self-formed "cage"

Theoretical insight into the activity and selectivity in palladium/Ming-Phos-catalyzed three-component asymmetric synthesis of gem-diarylmethine silanes

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Science China Chemistry 2023年第10期66卷 2817-2827页

作者： Bo xiao Tian-Yu Sun Junliang Zhang Yun-Dong Wu State Key Laboratory of Chemical Oncogenomics Key Laboratory of Computational Chemistry and Drug DesignSchool of Chemical Biology and BiotechnologyPeking University Shenzhen Graduate SchoolShenzhen 518055China Institute of Chemical Biology Shenzhen Bay LaboratoryShenzhen 518132China Department of Chemistry Fudan UniversityShanghai 200438China College of Chemistry and Molecular Engineering Peking UniversityBeijing 100871China

Recently,a three-component coupling reaction for efficient construction of gem-diarylmethine silanes was developed,utilizing a Pd-Ming-Phos *** explore the underlying mechanism governing this intriguing reaction,we have conducted comprehensive density functional theory(DFT)computations(M06-L/SDD/6-311++G(d,p)/SMD//B3LYP-D3/lanl2dz/6-31G(d,p)).DFT calculations reveal that the oxidative addition of Ar Br to Pd(0)is the rate-determining step,and the carbenation process of Ph CHN_(2)to Pd(Ⅱ)is the enantioselectivity-determining ***,the Ming-Phos ligand exhibits a self-adaptive nature,allowing it to dynamically adapt its coordination patterns with the metal center in different elementary steps,thereby enhancing the overall *** enantioselectivity is determined by both the trans effect and the side-arm effect of the *** mechanism nicely explains why TY-Phos with P-tBu_(2)instead of the Ming-Phos with P-Ph2results in poor reactivity and much reduced *** study not only provides deeper insights into the functioning principles of Sad Phos ligands but also offers valuable guidance for future ligand modifications and optimizations.

关键词： self-adaptive effect side-arm effect Ming-Phos ligand gem-diarylmethine silanes DFT study

Understanding the Moon's internal structure through moonquake observations and remote sensing technologies

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Science China Earth Sciences 2018年第8期61卷 995-1006页

作者： Weifeng HAO Fei LI Chi xiao Jianguo YAN Mao YE Chinese Antarctic Center of Surveying and Mapping Wuhan University State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University

Explorations for the interior structure of the Moon mainly involve three technologies: the early gravitational observations via circumlunar satellites, the moonquake observations during the Apollo period, and the recent high-resolution remote sensing observations. Based on these technologies, we divided the development of the moon's interior structure into three stages. The first stage is the discovery of high-density anomalous masses(mascons) on the lunar surface with the low-order gravitational field models, which were obtained by observing perturbations of the early lunar orbital satellites. The second stage is the preliminary understanding of the layer structure with the help of moonquake observations during the Apollo period. The third stage is the deep understanding of the structure of the lunar crust, mantle, and core, with the use of high-resolution remote sensing data and the reassessment of moonquake data from the Apollo's mission. This paper gave detailed introduction and comments on different observation technologies, gathered data, and data processing techniques used at the three stages. In addition, this paper analyzed the current issues in the researches on the Moon's internal structure and discussed the prospects for future explorations.

关键词： Moon Mascon Moonquake Remote sensing Lunar internal structure

Review of research on intelligent diagnosis of oil transfer pump malfunction

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Petroleum 2023年第2期9卷 135-142页

作者： Liangliang Dong Qian xiao Yanjie Jia Tianhai Fang School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500China Pipe China Southwest Pipeline Company Technology Center Chengdu 610017China Petro China Southwest Oil&Gasfield Company Chengdu610051China Oil and gas equipment technology Sharing and Service Platform of Sichuan ProvinceChina

Oil transfer pump is the key dynamic equipment in the process of oil and gas gathering and transportation,and its working reliability directly affects the safety of oil and gas storage and *** diagnosis is a key technical method to reduce failure rate of oil transfer pump,ensure the safety of gathering and transportation process,and avoid major safety accidents caused by oil transfer pump *** oil transfer pumps have been emerged in recent decades,and the common fault types and characteristics of oil transfer pump have been brought out in the *** article highlights on the research of the fault signal and processing methods of oil transfer ***,the fault signal of the oil transfer pump is discussed and the advantages and disadvantages of different signal extraction are ***,the intelligent diagnosis method of oil transfer pump and the shortcomings of the existing methods are pointed ***,the conclusions are given and the future development perspectives of oil transfer pumps are *** main contribution of this review is to give a syn-thetic understanding on oil transfer pumps.

关键词： Intelligent diagnosis Oil transfer pump Development trend

External photon fields in Fermi bright blazars

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Research in Astronomy and Astrophysics 2011年第8期11卷 902-908页

作者： xiao-Yan Gao Jian-Cheng Wang Ming Zhou National Astronomical Observatories / Yunnan Observatories Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The external Compton （EC） model is used to study the high energy emission of some blazars, in which the external photon field is considered to dominate inverse Compton radiation. We explore the properties of the external photon field through analyzing the FERMI LAT bright AGN sample within three months of the start of operations in sky-survey mode. In the sample, assuming the high energy radiation of low synchrotron peaked blazars is from the EC process, we find that the external photon parameter Uext/υext may not be a constant. Calculating synchrotron and inverse Compton luminosity from the quasi-simultaneous broadband spectral energy distributions, we find that they have an approximately linear relation. This indicates that the ratio of external photon and magnetic energy density is a constant in the comoving frame, implying that the Lorentz factor of the emitting blob depends on the external photon field and magnetic field. The result gives a strong constraint on the dynamic jet model.

关键词： galaxies: active -- galaxies: jets -- gamma-rays: galaxies --- radiationmechanism: non-thermal

The entanglement of several graph states

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Frontiers of physics 2012年第4期7卷 444-448页

作者：陈小余 College of Information and Electronic Engineering Zhejiang Gongshang University Hangzhou 310018 China

We exactly evaluate the entanglement of a six vertex and a nine vertex graph states which correspond to non ＂two-colorable＂ graphs. The upper bound of entanglement for five vertex ring graph state is improved to 2.9275, less than the upper bound determined by local operations and classical communication. An upper bound of entanglement is proposed based on the definition of graph state.

关键词： graph state closest separable state multipartite entanglement

Where can the low dielectric constant go in dense inorganic materials?

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Journal of Materiomics 2023年第5期9卷 980-983页

作者： Lei Li xiao Li Zhu Xiang Ming Chen Lab of Dielectric Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou310058China

In order to meet the requirements of future development in microelectronics and mobile communication,low-dielectricconstant(low-εr)materials have been receiving the increasing attention[1,2].The low-εr(εr<10 or evenεr<4)dielectric ceramics combined with ultra-low loss and near-zero temperature coefficient of resonant frequency are the crucial challenge for the resonator,filter and substrate applications in the future microwave communication towards millimeter wave band[1],and the semiconductor industry has been showing the increasing needs for ultralow-εr(<2)materials because the reduction of crosstalk,noise,and power consumption is becoming the key challenge as the feature size of microprocessors decreases[2].Although the ultralowεr can be achieved in some dense organic materials and porous inorganic materials[2e6],it is a big challenge to understand where can the lowεr go and how can we approach the lower limit of dielectric constant.

关键词： ceramics dielectric inorganic