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AN HREM STUDY OF A LATERAL MICROCRACK bENEATHINDENTATION OF [001] SILICON

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Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 342-346页

作者： Y.q.Wu X.Y.Yang Y.b.Xu Inst of Metal Research The Chinese Acad of Sciences Shenyang China

A cross-sectional sample of indentation in [001] silicon was made and a lateral microcrack beneath the indentation was observed by high resolution electron microscope (HREM). The HREM images around the microcrack tip show an alternate distribution of the amorphous and lattice structure. The crack does not propagate by the successive debonding between certain atomic planes, meaning that before a crack completely opens, there may be a stage of amorphization, resulting from severe distortion of lattice.

关键词： amorphization lateal crack indentation HREM silicon

Forced Convective Heat Transfer and Pressure Drop of Air Flowing in a Rectangle Duct with Cross-Ribs on the Opposite Walls

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Journal of Thermal Science 2002年第3期11卷 259-270页

作者： b.Deng T.T.Wong W.q.Tao School of Power and Energy Xi’an Jiaotong University Xi’an China Department of Mechanical Engineering The Hong Kong Polytechnic University Hong Kong

Experiments were conducted to investigate the forced convective heat transfer and flow friction of turbulent airflow in a rectangular duct with cross-ribs attached at the two principal walls in the Reynolds number range from 5000 to 40000. The effect of the rib cross angle (45° 60° 75° and the height (4 mm, 5 mm) of the cross-ribs on the forced convection and flow friction were tested. Non-dimensional correlations for the duct average Nusselt number and friction factor of cross-ribs duct were developed from the test data. Experiments were also conducted for the corresponding parallel ribs to compare their relative performance. The experimental results show that both of the convective heat transfer coefficient and friction factor were increased with cross-ribs, with 45°cross-ribs being the best. Compared with parallel ribs normal to the flow direction under identical flow rate and identical pumping power constraints, the cross-ribs can enhance heat transfer in the lower Reynolds number region, while

关键词： cross-ribs forced convection heat transfer enhancement.

THERMAL STRUCTURAL DISORDER AND MELTING TRANSITION IN HIGH-ANGLE GRAIN-bOUNDARY: A MOLECULAR-DYNAMICS STUDY

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Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 365-375页

作者： S.J.Zhao Y.C.Wang J.q.You q.b.Yang L.G.Zhou H.q.Ye Xiangtan Univ Xiangtan China

A structural transition in the fcc ∑=5 (120)/[001] high-angle tilt grain-boundary(Gb)is investigated by molecular-dynamics simulation. The calculations have been performed at various temperutures and the thermodynamic melting point Tm of the model system is determined by using a many-body potential fitted to copper. A thermal disorder transition in the Gb region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experiment results and theoretical *** we also observed that melting initiated at the interface and then propagated into the bulk quickly at or above Tm.

关键词： moleculandynamics grainboundary structural transition

TOTAL ENERGIES AND ELECTRONIC STRUCTURES OF CO_3Ti AND HYDROGENIZED Co_3Ti

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 197-201页

作者： S.q.Duan S.J.Liu b.K.Ma beijing Normal Univ Beijing China

Electronic structure calculations using the tighting-binding linear muffin-tin orbital (Tb-LMTO) method have been performed for Co3Ti and its hydride CO3Ti. The computed values of lattice constants and bulk moduli agree with the experiment values. The theoritical excess enerpy and lattice staid due to hydrogen absorption consequently obtained hem the ab initio results indicate that H has the tendency to stay in Co3Ti and the ionicities of Co atomic spheres due to hydmpen absorption change from the canons to the ations. On the other hand, the changes of band structures due to hydrogenation are found to be remarkable.

关键词： total enerpy electronic structure hydrogenized Co3Ti

High mechanical strengths and ductility of stainless steel 304L fabricated using selective laser melting

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Journal of Materials Science & Technology 2019年第2期35卷 388-394页

作者： q.b.Nguyen Z.Zhu F.L.Ng b.W.Chua S.M.L.Nai J.Wei Singapore Institute of Manufacturing Technology Institute of Research and Development Duy Tan University

Achieving not only high mechanical strengths but also high ductility is recently established using an additive manufacturing technique called selective laser melting. In the present study, stainless steel 304 L fully dense samples were successfully printed using the 3 D systems – ProX 300 printing machine. The ductility and tensile yield strength were almost two and three times higher compared to those of ASTM cast's alloy. Honey comb like nano-cellular structure with different orientation was observed in the fine grains(~4μm) due to fast cooling rate. In addition, the formation of martensite phase in random grains is also a contributor to the strengths. Furthermore, negative residual stresses in the build and horizontal directions were detected and assisted further increase in the tensile strength. Fractography revealed the ductile feature of plastic deformation and the crack openings at unmelted particles or pores.

关键词： Additive manufacturing Stainless steel Powder Selective laser melting

Anisotropy of the Wear behavior for Carbon Nanotube-Reinforced 6061Al Composites

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Acta Metallurgica Sinica(English Letters) 2023年第5期36卷 814-826页

作者： X.N.Li J.F.Zhang W.H.Xue K.Ma P.Y.Li Z.Y.Liu b.L.Xiao D.R.Ni q.Z.Wang D.Wang Z.Y.Ma School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

Carbon nanotube(CNT)-reinforced 6061Al(CNT/6061Al)composites with directionally aligned CNT were fabricated,and their wear behavior was *** results indicate that the wear properties of CNT/6061Al composites exhibited a significant anisotropy.A certain CNT concentrations(1 wt%and 2 wt%)could effectively improve the wear resistance of CNT/6061Al composites along the CNT circumferential and CNT radial directions for the load transfer,grain refinement and self-lubrication effect of *** brass{011}and{112}textures inhibited the load transfer effect of CNT along the CNT radial direction,resulting in a better wear resistance along CNT circumferential direction than CNT radial *** the CNT axial direction,the weak deformability of composites caused by the intensifyingfiber texture was the main reasons for the poor wear resistance of CNT/6061Al composites with increasing CNT concentration.

关键词： Carbon nanotube Metal matrix composite Wear Anisotropy

Spray drift characteristics of pulse-width modulation sprays in wind tunnel

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International Journal of Agricultural and biological Engineering 2022年第4期15卷 7-15页

作者： Longlong Li Liping Chen Ruirui Zhang qing Tang Tongchuan Yi boqin Liu Wei Deng Research Center of Intelligent Equipment Beijing Academy of Agricultural and Forestry SciencesBeijing 100097China qingyuan Smart Agriculture and Rural Research Institute Qingyuan 511500GuangdongChina National Research Center of Intelligent Equipment for Agriculture Beijing Academy of Agricultural and Forestry SciencesBeijing 100097China National Center for International Research on Agricultural Aerial Application Technology Beijing Academy of Agricultural and Forestry SciencesBeijing 100097China beijing Key Laboratory of Intelligent Equipment Technology for Agriculture Beijing Academy of Agricultural and Forestry SciencesBeijing 100097China College of Mechanical and Electronic Engineering Northwest A&F UniversityYangling 712100ShaanxiChina

Pulse-width modulation(PWM)sprays can improve flow accuracy by adjusting duty cycle and frequency signal which accurately controls the relative proportion of opening time of solenoid *** objective of this research was to determine the impacts of PWM duty cycle and frequency on spray drift *** tests were conducted in a wind tunnel with a PWM variable-rate spraying *** airborne drift and sediment drift were determined with tracer method,and the drift potential reduction(DPR)compared with reference condition of 100%duty cycle at vertical profile and horizontal planes were calculated,*** results show that,at a given frequency,droplet size decreases with the increase of duty cycle,the main reason is that the liquid does not reach full pattern development at lower duty *** cycle has a greater impact than the frequency on spray drift,the influence weights of duty cycle on airborne drift and sediment drift were 88.32%and 77.89%,*** a lower PWM frequency,in addition to the droplet size,the spray drift may be affected by the pulsed spray *** the perspective of reducing spray drift,it is recommended that the PWM duty cycle should be set in the range of 20%-70%to reduce the potential drift in PWM *** research provides a pesticide drift reduction scheme for variable spraying technology,which can serve as a theoretical basis for PWM parameter selection.

关键词： nozzle spray drift pulse-width modulation drift potential reduction droplets spectral

Physical insights from imaginary-time density–density correlation functions

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Matter and Radiation at Extremes 2023年第5期8卷 57-72页

作者： Tobias Dornheim Zhandos A.Moldabekov Panagiotis Tolias Maximilian böhme Jan Vorberger Center for Advanced Systems Understanding(CASUS) D-02826 GörlitzGermany Helmholtz-Zentrum Dresden-Rossendorf(HZDR) D-01328 DresdenGermany Space and Plasma Physics Royal Institute of Technology(KTH)Stockholm SE-10044Sweden Technische Universität Dresden D-01062 DresdenGermany

An accurate theoretical description of the dynamic properties of correlated quantum many-body systems,such as the dynamic structure factor S(q,ω),is important in many ***,highly accurate quantum Monte Carlo methods are usually restricted to the imaginary time domain,and the analytic continuation of the imaginary-time density–density correlation function F(q,τ)to real frequencies is a notoriously hard ***,it is argued that often no such analytic continuation is required because by definition,F(q,τ)contains the same physical information as does S(q,ω),only represented ***,it is shown how one can directly extract key information such as the temperature or quasi-particle excitation energies from theτdomain,which is highly relevant for equation-of-state measurements of matter under extreme conditions[*** et al.,***.13,7911(2022)].As a practical example,ab initio path-integral Monte Carlo results for the uniform electron gas(UEG)are considered,and it is shown that even nontrivial processes such as the roton feature of the UEG at low density[*** et al.,***.5,304(2022)]are manifested straightforwardly in F(q,τ).A comprehensive overview is given of various useful properties of F(q,τ)and how it relates to the usual dynamic structure *** fact,working directly in theτdomain is advantageous for many reasons and opens up multiple avenues for future applications.

关键词： imaginary continuation quantum

Ground-state mass of ^(22)Al and test of state-of-the-art ab initio calculations

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Chinese Physics C 2024年第3期48卷 72-78页

作者：孙铭泽于越王新鹏王猛李健国张玉虎 K.blaum 陈祖毅陈瑞九邓涵宇付超义葛文文黄文嘉焦红扬李红蕙李宏福罗胤芳廖挺 YuALitvinov 司敏帅鹏史金阳王茜邢元明徐星徐瑚珊许甫荣袁琪 T.Yamaguchi 颜鑫亮杨建成原有进周小红周旭张敏曾奇 CAS Key Laboratory of High Precision Nuclear Spectroscopy Institute of Modern PhysicsChinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Max-Planck-Institut für Kernphysik Saupfercheckweg 169117 HeidelbergGermany GSI Helmholtzzentrum für Schwerionenforschung Planckstraße 164291 DarmstadtGermany Advanced Energy Science and Technology Guangdong Laboratory Huizhou516007China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Department of Physics Saitama UniversitySaitama 338-8570Japan School of Nuclear Science and Engineering East China University of TechnologyNanchang 330013China

The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed bρ-defined isochronous mass spectrometry method at the cooler storage ring in *** new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 *** compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)*** excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field *** mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.

关键词： nuclear mass bρ-defined IMS mirror energy difference ab initio VS-IMSRG calculations chiral interactions