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Influence of Prior Austenite Deformation and Non-Metallic Inclusions on Ferrite Formation in Low-Carbon Steels

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Journal of Iron and Steel Research International 2010年第6期17卷 36-42页

作者： ZHANG Chi xia zhi-xin YANG zhi-gang LIU zhi-hao Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

Effects of prior austenite deformation and non-metallic inclusions on the ferrite nucleation and grain refine- ment of two kinds of low-carbon steels have been studied. The ferrite nucleation on MnS and V（C, N） is observed. The combination of thermomeehanical processes with adequate amounts of non-metallic inclusions formed in low-car- bon steels could effectively refine the grain size and the microstructure. Ferrite nucleated on the single MnS or V（C, N） inclusions and complex MnS＋V（C,N） inclusion. The proper addition of elements S and V could effectively promote the formation of ferrite and further refinement of ferrite grains.

关键词： austenite deformation non-metallic inclusion ferrite nucleation low-carbon steel

Effect of interface behaviour on damage and instability of PBX under combined tension-shear loading

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Defence Technology（防务技术） 2023年第5期23卷 137-151页

作者： Quan-zhi xia Yan-qing Wu Feng-lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China

To study the effect of interface behaviour on the mechanical properties and damage evolution of PBX under combined tension-shear loading, the present work establishes the numerical model of a PBX three-phase hybrid system, which introduces a nonlinear plastic damage cohesion model to study the mechanical response and damage process. The parameters in the model were fitted and *** the crack growth rate as the feature, the damage state in each stage was determined, and the damage instability criterion was given. The effects of interfacial tensile strength and shear strength on the damage process of PBX were studied. On this basis, serrated and hemispherical structures interface of PBX has been developed, which affects the damage process and instability during the loading *** results indicate that damage state response of PBX experiences the process of stable load bearing,unstable propagation, and complete failure. At the critical moment of instability, the overall equivalent effective strain of material reaches 3024 με and instability loading displacement reaches 0.39 mm. The increase of interfacial tensile strength and shear strength significantly inhibits the damage of PBX. The effect of interfacial shear strength on critical instability of PBX is approximately 1.7 times that of the interfacial tensile strength. Further, interface opening along the normal direction is the main damage form at the interface. Serrated and hemispherical rough interfaces can significantly inhibit propagation of cracks, and the load bearing capacity is improved by 22% and 9.7%, respectively. Appropriate improvement of the roughness of the interface structure can effectively improve the mechanical properties. It is significantly important to have a better understanding of deformation, damage and failure mechanisms of PBX and to improve our predictive ability.

关键词： PBX explosives Interface behaviour Damage Instability Crack propagation

Hamiltonicity of 4-connected Graphs

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Acta Mathematica Sinica,English Series 2010年第4期26卷 699-710页

作者： Hao LI Feng TIAN zhi xia XU LRI Univ. Paris-sud 11 and CNRS Orsay F-91405 France School of Mathematics and Statistics Lanzhou University Lanzhou 730000 P. R. China Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 P. R. China Center for Combinatorics and LPMC-TJKLC Nankai University Tianjin 300071 P. R. China Department of Mathematics Tianjin Polytechnic University Tianjin 300160 P. R. China

Let σk（G） denote the minimum degree sum of k independent vertices in G and α（G） denote the number of the vertices of a maximum independent set of G. In this paper we prove that if G is a 4-connected graph of ord... 详细信息

关键词： k-connected Hamiltonian insertible vertex crossing diagonals

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

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Chinese Journal of Aeronautics 2007年第3期20卷 193-201页

作者： LUO Zhen-bing xia zhi-xun XIE Yong-gao College of Aerospace and Materials Engineering National University of Defense Technology Changsha 410073 China

A primary air jet vectoring control system with a novel synthetic jet actuator （SJA） is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either ＂push＂ or ＂pull＂, one novel synthetic jet actuator can fulfill both ＂push＂ and ＂pull＂ functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.

关键词： jet vectoring control synthetic jet actuator slide block flow control

地应力影响下的五孔掏槽爆破岩石损伤效应研究

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火工品 2025年第1期 89-96页

作者：杨赛群葛立芳李洪伟夏治园安徽江南爆破工程有限公司安徽宣城242000 安徽江南化工股份有限公司安徽合肥230088 安徽理工大学化工与爆破学院安徽淮南232001

在地下矿山开采过程中,地应力对巷道掘进效率的影响日益显著。本研究以某地下铁矿为研究对象,采用有限元软件LS-DYNA模拟不同地应力条件下五孔掏槽爆破掏槽孔孔间延期时间对岩石损伤程度的影响。通过现场爆破实验和块度识别软件验证模... 详细信息

在地下矿山开采过程中,地应力对巷道掘进效率的影响日益显著。本研究以某地下铁矿为研究对象,采用有限元软件LS-DYNA模拟不同地应力条件下五孔掏槽爆破掏槽孔孔间延期时间对岩石损伤程度的影响。通过现场爆破实验和块度识别软件验证模拟结果,探究了地应力、孔间延期时间与岩石损伤程度之间的关系。研究结果表明,地应力由0 MPa增加到10 MPa,五孔掏槽爆破掏槽孔最佳延期时间由60 ms减少为10 ms,相应的岩石损伤程度降低79%。地应力对爆破远区岩石裂纹的发育影响较大,而对近区影响较小。现场实验进一步证实了数值模拟的结论,表明可以根据实际地应力大小合理设置延期时间,有效降低大块率,提高爆破效率。

关键词：五孔掏槽爆破地应力延期时间 LS-DYNA 损伤程度

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Imaging atmospheric turbulence,using entropy to quantify turbulence strength

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Research in Astronomy and Astrophysics 2020年第11期20卷 259-262页

作者： Lu Feng zhi-xia Shen Jing-Yao Hu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China

Vertical profile of turbulence strength(Cn2)is one of the most important attributes for evaluating a site’s astronomical *** seeing is commonly used for describing turbulence strength,it can only represent the integral of all layers of the turbulence above the *** techniques which can be applied to produce Cn2,such as DIMM-MASS,SCIDAR,etc.,all rely on rather complex systems to do the *** this paper,we present an idea to evaluate the relative strength of turbulence with entropies of short exposure images taken at different conjugated heights of the *** experimental results are also presented in the paper.

关键词： techniques telescope site testing

Concave Pt-Cu-Fe ternary nanocubes：One-pot synthesis and their electrocatalytic activity of methanol and formic acid oxidation

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Chinese Chemical Letters 2017年第1期28卷 60-64页

作者： Ying-xia Wang Chuan-Fei Liu Man-Li Yang Xi-Hui Zhao zhi-Xin Xue Yan-zhi xia Collaborative Innovation Center for Marine Biomass Fibers Materials and Textiles of Shandong Province Qingdao University Qingdao 266071 China Materials Science and Engineering College Qingdao University Qingdao 266071 China State Key Laboratory Cultivating Base for New Materials and Modern Textiles Qingdao University Qingdao 266071 China

Concave nanostructures may be developed to improve the specific mass activity of a catalyst for formic acid and methanol electro-oxidation. In this work, we report the elctrocatalytic oxidation of methanol and formic acid in acid medium over concave Pt-Cu-Fe ternary nanocubes（NCs）, obtained by the galvanic exchange of Pt and Fe on Cu NCs. The concave Pt-Cu-Fe NCs exhibited improved electrooxidation performance contrasted to Pt-Cu NCs and purchased commercial Pt/C as demonstrated by their improved durability, lower onset potential, and more preferable anti-poisoning properties. These properties are believed to originate from the tailored concave structure of the catalyst and possible synergetic effects among the components of the Pt-Cu-Fe NCs.

关键词： Pt-Cu-Fe NCs Nanoparticles Metals and alloys Methanol oxidation Formic acid oxidation

In memory of Prof. C. C. Li

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Protein & Cell 2019年第6期10卷 389-392页

作者： zhi xia Juan Tian xiaoling Wang Huanming Yang BGI-Shenzhen Shenzhen 518083 China

Professor Ching Chun Li (C. C. Li), one of the greatest geneticists in the world and a pioneer of genetics in China, passed away fifteen years ago (Fig. 1). Let us remember him together.**Do you know who the greatest, world-renown Chinese geneticist is?" The answer,**C. C. Li, of course!” would puzzle most, if not all, of us;many in our generation don't know Who is Who (Atte ntion! Li, not Lee, the latter of which was gen erally used as the general spelli ng of that gen eration)(Fig. 2).

关键词： In memory of Prof.C.C.Li greatest geneticists latter

Reversible electrochemistry of DNA on multi-walled carbon nanotube modified electrode

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Chinese Chemical Letters 2007年第7期18卷 861-864页

作者： Hong xia Luo zhi Xin Guo Nan He Department of Chemistry Renmin University of China Beijing 100872 China

Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues,respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans.

关键词： Carbon nanotube DNA Cyclic voltammetry Reversible