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Astrometric Observations of NEA 1998 HH49 Using the Daocheng 50 cm Telescope

Research in Astronomy and Astrophysics 2024年第7期24卷 71-78页

作者： Huan Xu Xiang-Ming Cheng Yi-Gong zhang Teng-Fei Song zhen-jun zhang Qing-Yu Peng Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Engineering Laboratory on Applied Astronomical Technology of Yunnan Kunming 650216China School of Information Engineering Kunming UniversityKunming 650214China School of Computer Science and Information Engineering Anyang Institute of TechnologyAnyang 455000China Department of Computer Science Jinan UniversityGuangzhou 510632China Sino-French Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China

This study details an astrometric observation campaign of the Near-Earth Asteroid 1998 HH49,conducted with the aim of refining our understanding of its physical *** the 50 cm telescope located at the Wumingshan Mountain in Daocheng,Sichuan,images were obtained over four nights,from 2023 October 19 to October *** observations were processed using Astrometrica software,facilitating the precise determination of the asteroid's *** observational results were compared with the ephemerides from three distinct sources to verify accuracy:the Jet Propulsion Laboratory(JPL)Horizons System,the Institut de Mécanique Céleste et de Calcul deséphémérides(IMCCE)Miriade,and the Near-Earth Objects Dynamic Site(NEODyS-2).When compared with the JPL ephemeris,a mean observed-minus-calculated(O-C)result of 0.″07 in the *** and-0.″35 in the *** was ***,the comparison with the IMCCE ephemeris yielded mean O-C results of 0.″08 in the *** and-0.″06 in the *** comparison with the NEODyS-2 ephemeris yielded the mean O-C results of 0.″06 in ***-0.″49 in *** study's findings demonstrate a general consistency between the observed data and the ephemeris predictions,with minor discrepancies observed across the data ***,both the JPL and NEODyS-2 ephemerides show that the residuals in the *** exceed those in the *** disparities may result from atmospheric differential color refraction,ephemeris discrepancies,observational errors,and other ***,it is worth noting that further investigation is required due to the potential influence of additional ***,the Daocheng 50 cm Telescope exhibits the ability to conduct high-precision positional measurements.

关键词： astrometry ephemerides time

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Exploring the Possibility of Deformation Twinning in Pure Aluminum

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Acta Metallurgica Sinica(English Letters) 2016年第7期29卷 647-651页

作者： Tuo Cai zhen-jun zhang Jin-Bo Yang Zhe-Feng zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

Can aluminum generate deformation twins？ Contradictories exist among the experimental results, theoretical predictions, and molecular dynamics simulations. Our first-principles calculations based on the full-potential linearly augmented plane wave method show that the bonding electron density of aluminum gathers at the tetrahedral interstices, and this specific electronic structure is in agreement with the experimental data from quantitative convergent-beam electron diffraction. In terms of this characteristic, the matching between the cohesive energy of local deformation twins with different thickness and global matrix can shed light on deformation twins in aluminum. This study may give a lane to insight into deformation twins in different metals.

关键词： Metals and alloys Deformation twinning First-principles Density functional theory

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A Novel Method for Achieving Gradient Microstructure in a Cu-Al Alloy:Surface Spinning Strengthening (3S)

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Acta Metallurgica Sinica(English Letters) 2017年第3期30卷 212-217页

作者： Chuan-Xi Ren QiangWang zhen-jun zhang Yan-Kun Zhu Zhe-Feng zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China School of Materials Science and Engineering University of Science and Technology of China Hefei 230026 China

A new designed surface strengthening method, surface spinning strengthening （3S）, was applied to achieve gradient microstructure in the surface layer of a Cu-11 at.%A1 alloy. According to the level of grain refinement, the gradient microstructure can be divided into four zones, including nanoscale grain zone, ultra-fine grain zone, fine grain zone and coarse grain zone from the surface to the matrix. Meanwhile, a plenty of grain boundaries and twin boundaries were introduced to inhibit the dislocation motion in the surface layer during the plastic deformation process. Consequently, the hardened layer with a microhardness gradient and high residual compressive stress was produced on the samples, and the yield strength of the Cu-11 at.%A1 alloy was effectively improved after 3S processing due to the strengthening effect caused by the gradient microstructurc.

关键词： Cu-AI alloy Surface spinning strengthening (3S) Strength Microhardness Gradientmicrostructure

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The criterion of anomalous slip at OK in body centered cubic metals

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Tungsten 2023年第1期5卷 160-168页

作者： zhen-jun zhang Shuang-Li Lu Jin-Bo Yang Zhe-Feng zhang Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

It is generally accepted that anomalous slip(AS) takes place by hexagonal dislocation networks(HDNs) in body centered cubic(BCC) metals,but the role of the HDN formation process in AS has rarely been investigated so *** this work,the critical yield conditions of the HDNs and isolated dislocations were first calculated,respectively,by molecular statics simulations in two BCC *** on these data,a novel mechanism,entitled as the "conjugated dislocation sources"(CDS),to analyze the formation of the HDNs was proposed for the first time and then incorporated into the criterion of the occurrence of *** prediction is in agreement with experimental *** to previous study,it has been revealed that the multiplication of isolated screw dislocations involved in AS has to be considered for correctly understanding the AS origin.

关键词： Anomalous slip Hexagonal dislocation network Body centered cubic metal Yield criterion

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CCD astrometric observations of 2017 VR12, Camillo and Midas

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Research in Astronomy and Astrophysics 2019年第5期19卷 91-100页

作者： zhen-jun zhang Yi-Gong zhang Xiang-Ming Chen Jian-Cheng Wang Jie Su Yunnan Observatories Chinese Academy of Sciences Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences University of Chinese Academy of Sciences

We have observed three near-Earth objects(NEOs), 2017 VR12, Camillo and Midas, during *** observations were made with the 1-m telescope, operated by Yunnan Observatories, over two *** precise astrometric positions are derived from 989 CCD observations. The theoretical positions of asteroids are retrieved from the Jet Propulsion Laboratory(JPL) Horizons System and Institut de M′ecanique C′eleste et de Calcul des ′Eph′em′erides(IMCCE). The positions of three asteroids are measured with respect to stars in the Gaia DR2 star catalog. For 2017 VR12, the means(O-C) of right ascension and declination are -0.090′′and-0.623′′respectively based on the published JPL ephemeris, but the corresponding means(O-C) are 3.122′′and-0.636′′based on the published IMCCE ephemeris. The great difference in declination could be explained by several factors.(1) The degraded CCD images caused by the fast apparent motion of the objects lead to a reduction in positioning accuracy.(2) The poor timing system may introduce systematic errors, especially in the high speed direction.(3) The asteroid may be perturbed by Earth when it approaches the Earth too closely. These astrometric results demonstrate that the centroid centering method can reduce the dispersion of non-Gaussian images as compared with the PSF modeling *** Camillo and Midas, the astrometric results are consistent based on the two ephemerides. Implementing a high-precision timing system, and analyzing some astronomical effects and geometric distortions in CCD images should be carefully considered in future works.

关键词： astrometry:astrometric observation NEOs:individual(2017 VR12,Camillo,Midas)

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Effective Stacking Fault Energy in Face-Centered Cubic Metals

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Acta Metallurgica Sinica(English Letters) 2018年第8期31卷 873-877页

作者： Ke-Qiang Li zhen-jun zhang Lin-Lin Li Peng zhang Jin-Bo Yang Zhe-Feng zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

As a typical configuration in plastic deformations, dislocation arrays possess a large variation of the separation of the partial dislocation pairs in face-centered cubic（fcc） metals. This can be manifested conveniently by an effective stacking fault energy（SFE）. The effective SFE of dislocation arrays is described within the elastic theory of dislocations and verified by atomistic simulations. The atomistic modeling results reveal that the general formulae of the effective SFE can give a reasonably satisfactory prediction for all dislocation types, especially for edge dislocation arrays. Furthermore, the predicted variation of the effective SFE is consistent with several previous experiments, in which the measured SFE is not definite, changing with dislocation density. Our approach could provide better understandings of cross-slip and the competition between slip and twinning during plastic deformations in fcc metals.

关键词： Face-centered cubic Stacking fault energy - Dislocation dissociation Atomistic modeling

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IMPROVEMENT OF TCAM-BASED PACKET CLASSIFICATION ALGORITHM

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Journal of Electronics(China) 2008年第2期25卷 239-245页

作者： Xu zhen zhang jun Rui Liyang Sun jun The School of Electronics and information Engineering Beijng University of Aeronautics and Astronautics Beijing 100083 China

The feature of Ternary Content Addressable Memories(TCAMs) makes them particularly attractive for IP address lookup and packet classification applications in a router system. However,the limitations of TCAMs impede their utilization. In this paper,the solutions for decreasing the power consumption and avoiding entry expansion in range matching are addressed. Experimental results demonstrate that the proposed techniques can make some big improvements on the performance of TCAMs in IP address lookup and packet classification.

关键词： Packet classification Address lookup Ternary Content Addressable Memory (TCAM) Energy-efficient design

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Dissociation of Tilt Dislocation Walls in Au

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Acta Metallurgica Sinica(English Letters) 2022年第11期35卷 1787-1792页

作者： Yu-Juan Geng Chun-Yang Wang Jing-Xin Yan zhen-jun zhang Hua-Jie Yang Jin-Bo Yang Kui Du Zhe-Feng zhang Shi-Changxu Innovation Centerfor Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Chongqing Jiaotong UniversityChongqing 400074China

The movement or dissociation of dislocations is signifi cantly important for better understanding the plastic deformation mechanisms and mechanical properties of *** is commonly believed that a dislocation/2 in Au is easy to dissociate into a pair of Shockley partial dislocations/6 due to low stacking fault energy(SFE).Contrary to this prevailing perception,the present atomistic modeling demonstrates that this reaction could be completely suppressed when dislocations/2 are grouped into tilt walls,consistent with our experimental *** phenomenon is actually the extreme case accompanying with the variation of Burgers vectors of partials with tilt angle,as revealed by a series of simulations,from which it is clearly seen that the Burgers vectors of partials deviate considerably from that of Shockley partials,enormously depending on the tilt *** fi ndings could facilitate a better understanding on many phenomena and properties of face-centered cubic metals(FCC).

关键词： Dislocation Tilt wall Stacking fault Dissociation Grain boundary

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Drug-eluting stents improve clinical outcomes in Chinese diabetic patients with de novo coronary artery disease

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Chinese Medical Journal 2006年第18期119卷 1576-1579页

作者： zhang Qi FANG Yue-hua zhang Rui-yan HU Jian YANG zhen-kun NI jun zhang Jian-sheng SHEN Wei-feng Department of Cardiology Shanghai Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai 200025 China

Diabetes mellitus （DM） has been regarded as an equivalent risk factor as coronary artery disease and is present in nearly 25% of patients who receive percutaneous coronary intervention （PCI）. DM is shown as an adverse predictor for major adverse cardiac events （MACE） after PCI in bare metal stent （BMS） era. Recently, clinical trials have demonstrated the favorable tendency of using drug-eluting stents （DES） in treating diabetic patients with coronary artery disease. This study compared the clinical outcomes between the diabetic patients receiving DES with those receiving BMS in China.

关键词： coronary disease diabetes mellitus drug-eluting stent outcome assessment

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S-scheme regulated Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S hetero-homojunctions for efficient photocatalytic H_(2)evolution

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Journal of Materials Science & Technology 2024年第2期169卷 148-157页

作者： Qiqi zhang zhen Wang Yuhang Song jun Fan Tao Sun Enzhou Liu School of Chemical Engineering/Xi’an Key Laboratory of Special Energy Materials Northwest UniversityXi’an 710069China

Effective bulk phase and surface charge separation is critical for charge utilization during the photo-catalytic energy conversion *** this work,the ternary Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S(T-MCS)nanohybrids were successfully constructed via combining Ni_(2)P-NiS with T-MCS solid solution for visible light photocatalytic H_(2)evolution.T-MCS is composed of zinc blende Mn_(0.5)Cd_(0.5)S(ZB-MCS)and wurtzite Mn_(0.5)Cd_(0.5)S(WZ-MCS)and those two alternatively arranged crystal phases endow T-MCS with excellent bulk phase charge separation performance for the slight energy level difference between ZB-MCS and WZ-MCS.S-scheme carriers transfer route between NiS and T-MCS can accelerate the interfacial charge separation and retain the active electrons and holes,meanwhile,co-catalyst Ni_(2)P as electron receiver and proton reduction center can further optimize the H_(2)evolution reaction kinetics based on the surface Schottky barrier *** above-formed homo-heterojunctions can establish multiple charge transfer channels in the bulk phase of T-MCS and interface of T-MCS and Ni_(2)*** the synergistic effect of twinned homojunction,S-scheme heterojunction,and Schottky barrier,the ternary Ni_(2)P-NiS/T-MCS com-posite manifested an H_(2)production rate of 122.5 mmol h^(-1)g^(-1),which was 1.33,1.24,and 2.58 times higher than those of the NiS/T-MCS(92.4 mmol h^(-1)g^(-1)),Ni_(2)P/T-MCS(98.4 mmol h^(-1)g^(-1)),and T-MCS(47.5 mmol h^(-1)g^(-1)),*** work demonstrates a promising strategy to develop efficient sul-fides photocatalyst toward targeted solar-driven H_(2)evolution through homo-heterojunction engineering.

关键词： Photocatalytic H_(2)evolution Twinned Mn_(0.5)Cd_(0.5)S Homojunction S-scheme heterojunction Schottky barrier

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