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Effects of rarefaction on the characteristics of micro gas journal bearings

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第1期11卷 43-49页

作者： hai-jun zhang Chang-sheng ZHU Ming TANG College of Electrical Engineering Zhejiang University Hangzhou 310027 China College of Mechanical-Electrical Engineering Jiaxing University Jiaxing 314001 China

Given the definition of the reference Knudsen number for micro gas journal bearings,the range in the number is related to the viscosity of air at different temperatures. A modified Reynolds equation for micro gas journal bearings based on Burgdorfer's first-order slip boundary condition is proposed that takes into account the gas rarefaction effect. The finite difference method (FDM) is adopted to solve the modified Reynolds equation to obtain the pressure profiles,load capacities and attitude angles for micro gas journal bearings at different reference Knudsen numbers,bearing numbers and journal eccentricity ratios. Numerical analysis shows that pressure profiles and non-dimensional load capacities decrease markedly as gas rarefaction in-creases. Attitude angles change conversely,and when the eccentricity ratio is less than 0.6,the attitude angles rise slightly and the influence of the reference Knudsen number is not marked. In addition,the effect of gas rarefaction on the non-dimensional load capacity and attitude angle decreases with smaller bearing numbers.

关键词： Reference Knudsen number Rarefaction effect Reynolds equation Finite difference method (FDM)

New numerical solution for self-acting gas journal bearings

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 685-690页

作者： hai-jun zhang Chang-sheng ZHU Qin YANG College of Electrical Engineering Zhejiang University Hangzhou 310027 China College of Mechanical and Electrical Engineering Jiaxing University Jiaxing 314001 China

Taking a small pressure change in the gas film of self-acting gas-lubricated journal bearings into account, the corresponding nonlinear Reynolds equation is linearized through appropriate approximation and a modified Reynolds equation is derived and solved by means of the finite difference method (FDM). The gas film pressure distribution of a self-acting gas-lubricated journal bearing is attained and the load capacity is calculated. The numerical solution has a better agreement with experimental data than a direct numerical solution for different values of the bearing number. It is of interest to note that the eccentricity ratio, at which the new numerical solution is in better agreement with experimental data, is different when the bearing number is changing. The new numerical solution is slightly larger when the eccentricity ratio is smaller, and becomes slightly smaller when the eccentricity ratio is larger.

关键词： Self-acting gas journal bearings Reynolds equation Nonlinearity Finite difference method (FDM)

Growth characteristics of directionally solidified Al_2O_3/YAG/ZrO_2 ternary hypereutectic in situ composites under ultra-high temperature gradient

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International Journal of Minerals,Metallurgy and Materials 2011年第1期18卷 121-125页

作者： hai-jun Su jun zhang Lin Liu Heng-zhi Fu State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China

Oxide eutectic ceramic in situ composites have attracted significant interest in the application of high-temperature structural materials because of their excellent high-temperature strength,oxidation and creep resistance,as well as outstanding microstructural *** directionally solidified ternary Al2O3/YAG/ZrO2 hypereutectic in situ composite was successfully prepared by a laser zone remelting method,aiming to investigate the growth characteristic under ultra-high temperature *** microstructures and phase composition of the as-solidified hypereutectic were characterized by using scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.The results show that the composite presents a typical hypereutectic lamellar microstructure consisting of fine Al2O3 and YAG phases,and the enriched ZrO2 phases with smaller sizes are randomly distributed at the Al2O3/YAG interface and in Al2O3 *** power and scanning rate strongly affect the sample quality and microstructure ***,coarse colony microstructures were also observed,and their formation and the effect of temperature gradient on the microstructure were discussed.

关键词： eutectics ceramic materials microstructure thermal gradients remelting solidification

Estimation on Geometric Measure of Quantum Coherence

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Communications in Theoretical Physics 2017年第2期67卷 166-170页

作者： hai-jun zhang School of Mathematical Sciences Capital Normal University Beijing 100048 China College of Science China University of Petroleum Qingdao 266580 China State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China Max-Planck-Institute for Mathematics in the Sciences 04103 Leipzig Germany Collaborative Innovation Center of Quantum Matter Beijing 100084 China

We study the geometric measure of quantum coherence recently proposed in [Phys. Rev. Lett. 115(2015)020403]. Both lower and upper bounds of this measure are provided. These bounds are shown to be tight for a class of important coherent states—maximally coherent mixed states. The trade-off relation between quantum coherence and mixedness for this measure is also discussed.

关键词： coherence measure super-fidelity sub-fidelity

Dynamic alterations in early intestinal development,microbiota and metabolome induced by in ovo feeding of L-arginine in a layer chick model

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Journal of Animal Science and Biotechnology 2020年第3期11卷 896-911页

作者： Dong Dai Shu-geng Wu hai-jun zhang Guang-hai Qi Jing Wang Laboratory of Quality&Safety Risk Assessment for Animal Products on Feed Hazards(Beijing)of the Ministry of Agriculture&Rural Affairs and National Engineering Research Center of Biological FeedFeed Research InstituteChinese Academy of Agricultural Sciences12 Zhongguancun South St.Haidian DistrictBeijing 100081China

Background:Prenatal nutrition is crucial for embryonic development and neonatal growth,and has the potential to be a main determinant of life-long *** the present study,we used a layer chick model to investigate the effects of in ovo feeding(IOF)of L-arginine(Arg)on growth,intestinal development,intestinal microbiota and *** treatments included the non-injected control,saline-injected control,and saline containing 2,6,or 10 mg Arg ***:IOF Arg increased early intestinal index and villus height,and enhanced uptake of residual yolk lipid,contributing to subsequent improvement in the early growth performance of *** Arg supplementation also increased the early microbialα-diversity,the relative abundance of Lactobacillales and Clostridiales,and decreased the relative abundance of Proteobacteria of cecum in ***,the shift of cecal microbiota composition and the colonization of potential probiotics were accelerated by IOF of ***,metabolomics showed that metabolisms of galactose,taurine-conjugated bile acids and lipids were modulated to direct more energy and nutrients towards rapid growth of intestine at the beginning of post-hatch when embryos received IOF of ***:Prenatal Arg supplementation showed beneficial effects on the early intestinal development,cecal microbiota and host metabolism of layer chicks,contributing to subsequent improvement in the early growth *** findings provide new insight into the role of IOF of Arg in the establishment of the gut microbiota of newly-hatched layer chicks,and can expand our fundamental knowledge about prenatal nutrition,early bacterial colonization and intestinal development in neonate.

关键词： Development In ovo feeding Intestinal microbiota L-arginine Layer chick Metabolomics

One-way quantum deficit and quantum coherence in the anisotropic X Y chain

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Science China(Physics,Mechanics & Astronomy) 2017年第3期60卷 42-47页

作者： Biao-Liang Ye Bo Li Li-jun Zhao hai-jun zhang Shao-Ming Fei School of Physics and Electronic Information Shangrao Normal University Shangrao 334001 China School of Mathematics & Computer Science Shangrao Normal University Shangrao 334001 China School of Mathematical Sciences Capital Normal University Beijing 100048 China Max-Planck-lnstitute for Mathematics in the Sciences Leipzig 04103 Germany

In this study, we investigate pairwise non-classical correlations measured using a one-way quantum deficit as well as quantum coherence in the XY spin-1/2 chain in a transverse magnetic field for both zero and finite temperatures. The analytical and numerical results of our investigations are presented. In the case when the temperature is zero, it is shown that the one-way quantum deficit can characterize quantum phase transitions as well as quantum coherence. We find that these measures have a clear critical point at λ = 1. When λ 1, the one-way quantum deficit has an analytical expression that coincides with the relative entropy of coherence. We also study an XX model and an Ising chain at the finite temperatures.

关键词： one-way quantum deficit quantum coherence quantum phase transitions XY chain

Catalytic Asymmetric Mannich-Type Reaction Enabled by Efficient Dienolization of α,β-Unsaturated Pyrazoleamides

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Chinese Journal of Chemistry 2021年第1期39卷 55-61页

作者： hai-jun zhang Feng Zhong Yan-Cheng Xie Liang Yin CAS Key Laboratory of Synthetic Chemistry of Natural Substances Center for Exellence in Moleculor SynthesisShanghai Istitute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences345 Lingling RoadShanghai 200032China

(E)-α,β-Unsaturated pyrazoleamides undergo facile dienolization to furnish copper(I)-(1Z,3Z)-dienolates as the major in the presence of a copper(I)-(R)-DTBM-SEGPHOS catalyst and EtgN,which react with aldimines to afford syn-vinylogous products as the major dia-stereoisomers in high regio-and *** some cases,the diastereoselectivity is low,possibly due to the low ratio of copper(I)-(1Z,3Z)-dienolates to copper(I)-(1Z,3E)-dienolates.

关键词： Asymmetric catalysis Vinylogous reaction Pyrazoleamide Copper catalyst Dienolization

Tungsten disulfide: synthesis and applications in electrochemical energy storage and conversion

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Tungsten 2020年第3期2卷 217-239页

作者： Wen Lei jun‑Lei Xiao hai‑Peng Liu Quan‑Li Jia hai‑jun zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China Henan Key Laboratory of High Temperature Functional Ceramics Zhengzhou UniversityZhengzhou 450052China

Recently,two-dimensional transition metal dichalcogenides,particularly WS_(2),raised extensive interest due to its extraordi-nary physicochemical *** the merits of low costs and prominent properties such as high anisotropy and distinct crystal structure,WS_(2) is regarded as a competent substitute in the construction of next-generation environmentally benign energy storage and conversion *** this review,we begin with the fundamental studies of the structure,properties and preparation of WS_(2),followed by detailed discussions on the development of various WS_(2) and WS_(2)-based composites for electrochemical energy storage and conversion *** the end,some prospective prospects and promising develop-ments of WS_(2) in these fields are proposed.

关键词： Transition metal dichalcogenides Tungsten disulfide Exfoliation Energy storage and conversion

Hierarchical microstructure and two-stage corrosion behavior of a high-performance near-eutectic Zn-Li alloy

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Journal of Materials Science & Technology 2021年第21期80卷 50-65页

作者： Zhen Li zhang-Zhi Shi hai-jun zhang Hua-Fang Li Yun Feng Lu-Ning Wang Beijing Advanced Innovation Center for Materials Genome Engineering School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing100083China Department of Interventional and Vascular Surgery The Tenth People's Hospital of ShanghaiTongji UniversityShanghai200072China National United Engineering Laboratory for Biomedical Material Modification Branden Industrial ParkQihe Economic&Development ZoneDezhou CityShandongDezhou251100China Ophthalmology Department Peking University Third HospitalPeking UniversityBeijing100083China

In order to improve mechanical and corrosion properties of biodegradable pure Zn,a knowledge-based microstructure design is performed on Zn-Li alloy system composed of hard β-LiZn_(4) and soft Zn *** and multi-modal grain structure are designed to toughen β-LiZn_(4) while strengthen Zn,resulting in high strength and high ductility for both the ***-like secondary Zn precipitates form in β-LiZn4,while fine-scale networks of string-like β-LiZn4 precipitates form in Zn with a tri-modal grain *** a result,near-eutectic Zn-0.48 Li alloy with an outstanding combination of high strength and high ductility has been fabricated through hot-warm rolling,a novel fabrication process to realize the microstructure *** as-rolled alloy has yield strength(YS) of 246 MPa,the ultimate tensile strength(UTS) of 395 MPa and elongation to failure(EL) of 47 %.Immersion test in simulated body fluid(SBF) for 30 days reveals that Li-rich products form preferentially at initial stage,followed by Zn-rich products with prolonged *** insoluble Li_(2) CO_(3) forms a protective passivation film on the alloy surface,which suppresses the average corrosion rate from 81.2 μm/year at day one down dramatically to 18.2 μm/year at day ***,the average corrosion rate increases slightly with decrease of Li2 CO_(3) content,which undulates around the clinical requirements on corrosion resistance(i.e.,20 μm/year) claimed for biodegradable metal stents.

关键词： Zn alloy Microstructure design Mechanical properties Interfacial structure Corrosion passivation