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Effect of nitrogen on deposition and field emission properties of boron-doped micro-and nano-crystalline diamond films

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Nano-Micro Letters 2010年第3期2卷 154-159页

作者： L.A.Li S.H.Cheng H.D.Li Q.yu J.W.Liu x.y.lv State Key Laboratory of Superhard Materials Jilin University

In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor *** diamond films consisting of micro-grains(nano-grains) were realized with low(high) boron source flow rate during the growth *** transition of micro-grains to nano-grains is speculated to be strongly(weekly) related with the boron(nitrogen) flow *** grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow *** variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples,which are related to the combined phase composition,boron doping level and texture *** is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films.

关键词： Chemical vapor deposited diamond film Nitrogen effect Boron doping Microcrystalline Nanocrystalline Electron field emission

An Efficient Parallel/Unstructured-Multigrid Implicit Method for Simulating 3D Fluid-Structure Interaction

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Communications in Computational Physics 2008年第7期4卷 350-377页

作者： x.lv y.Zhao x.y.Huang G.H.xia x.H.Su School of Mechanical and Aerospace Engineering College of EngineeringNanyang Technological UniversitySingapore 639798.

A finite volume(FV)method for simulating 3D Fluid-Structure Interaction(FSI)is presented in this *** fluid flow is simulated using a parallel unstructured multigrid preconditioned implicit compressible solver,whist a 3D matrix-free implicit unstructured multigrid finite volume solver is employed for the structural *** two modules are then coupled using a so-called immersed membrane method(IMM).Large-Eddy Simulation(LES)is employed to predict *** from several moving boundary and FSI problems are presented to validate proposed methods and demonstrate their efficiency。

关键词： Finite volume method moving boundary fluid-structure interaction unstructured multigrid computational structural mechanics immersed membrane method large-Eddy simulation.

Further numerical investigation on concrete dynamic behaviors with considering stress non-equilibrium in SHPB test based on the waveform features

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Acta Mechanica Sinica 2020年第4期36卷 873-886页

作者： T.H.lv x.W.Chen y.J.Deng G.Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province Southwest University of Science and TechnologyMianyang 621000China Institute of Systems Engineering China Academy of Engineering PhysicsMianyang 621999China

In this study,with the meso-scale model reliably validated in our previous work(Construction and Building Materials,2018),the waveform features of plain concrete under various loading conditions and especially with considering stress non-equilibrium are reliably reproduced and *** with waveform features,the violation indicator of the specimen stress equilibrium in the split Hopkinson pressure bar test is identified for concrete-like damage softening *** concrete material behaviors for stress non-equilibrium are further analyzed,*** dynamic increase factor(DIF)and damage development,*** conception of“damage failure volume”is introduced,and a new method of defining the development of concrete dynamic damage is given in the nimierical ***’s more,the“compression wave”and“double peak”phenomena observed in the experiment are further interpreted based on the means of numerical *** features how to reflect the concrete material properties is also *** results show that,the disappearance of the“double peak” phenomenon of reflection curve under high strain rate can be regarded as the indicator of the violation of stress *** the violation of the stress equilibrium,the relevant DIFs of the concrete specimen will not change ***,the concrete specimen will turn into structural response from material *** conception of“damage failure volume”can well explain the generation of the“double peak”phenomenon of the reflection *** “compression wave” phenomenon of reflection curve under lower strain rates is derived from the unloading expansion recovery of the concrete ***,under the same loading condition,the amplitude of the first peak of the reflection curve can be used as the evaluation standard of the bonding quality between mortar and aggregates.

关键词： Concrete material Split Hopkinson pressure bar test Numerical investigation Waveform feature Stress non-equilibrium Damage failure volume

PHySICAL SIMULATION BASED INTELLIGENT SySTEM FOR THE PREDICTION OF SHEET METAL DRAWING CAPABILITy

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Acta Metallurgica Sinica(English Letters) 2000年第2期13卷 451-458页

作者： D.lv D.N.He x.J.Bao y.Q.Zhang x.y.Ruan J.L.Cheng J.y.Jiang National Die&Mold CAD Engineering Research Center Shanghai Jiaotong UniversityShanghai 200030China Shanghai Volkswagen Automotive Company Limited Shanghai 201805China

With the combination of a new theoretical formula, physical simulation experiments, the technology of artificial neural network and database, an intelligent system for the prediction of sheet metal drawing capability is constructed for the first time. A modified criterion for sheet metal drawing capability is proposed in this paper, namely, the Technological Limiting Drawing Ratio, TLDR = f(R, n, s, t, F, μ,r_d,r_p…). Based on the studies of other scholars, a new formula is derived to predict the TLDR in this paper. Then a series of orthogonal physical simulation experiments are designed to investigate the effect of technological parameters on the TLDR, and the results are analyzed in the paper. Then the predicting system is constructed with the combination of the theoretical formula, orthogonal experiments, the technology of artifocial neural network and database. The predicted results show good agreements with experimental data, so it can be used to avoid the blindness in the selection of sheet metal before stamping. The system operates under the Windows operating system, and it supports the mechanism of Client/Server as well as Intranet, so the system has high engineering value.

关键词： TLDR theoretical analysis physical simulation orthogonal experiments neural network database predicting system

RESEARCH ON THE EVALUATION METHOD OF FRICTION AND LUBRICATION IN DEEP DRAWING

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Acta Metallurgica Sinica(English Letters) 2000年第2期13卷 439-445页

作者： D.N.He x.F.yin H.Z.Thao D.lv x.y.Ruan J.L.Cheng J.y.Jiang Shanghai Jiao Tong University National Die&Mold CAD E.R.CShanghai 200030China Shanghai Vopkswagen Automotive Company Ltd. Shanghai 201805China

The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other plastic process. The common test methods in laboratories are analyzed. It shows that though all those test methods can test the friction coefficient, the probe test method is most suitable for the research of friction and lubrication and the process in deep drawing, for this method is identical with the actual work condition either from the test principle or deformation status of the blank. Last the successful application in the deep drawing simulator newly developed the the probe method are intro- duced in detail.

关键词： deep drawing probe test method friction and lubrication evaluation method

In situ TEM investigation of electron irradiation and aging-induced high-density nanoprecipitates in an Mg-10Gd-3y-1Zn-0.5Zr alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1841-1853页

作者： M.lv H.L.Ge Q.Q.Jin x.H.Shao y.T.Zhou B.Zhang x.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3y-1Zn-0.5Zr(GWZ1031K,wt.%)alloy to improve the *** results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250℃ is 1.64 GPa,which is approximately 64% higher than that of the samples before being *** is mainly attributed to γ'precipitates on the basal plane after irradiation and the high-density nanoscale β'precipitates on the prismatic plane after aging,which should be closely related to the irradiation-induced homogenous *** latter plays a key role in precipitation *** result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

关键词： Mg alloy Electron beam irradiation Hardening Precipitates In-situ TEM

III-Nitride-Based Quantum Dots and Their Optoelectronic Applications

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Nano-Micro Letters 2011年第3期3卷 200-207页

作者： G.E.Weng A.K.Ling x.Q.lv J.y.Zhang B.P.Zhang Department of Physics Laboratory of Micro-Nano Optoelectronics Xiamen University MEMS Research Center Xiamen University

During the last two decades, III-nitride-based quantum dots(QDs) have attracted great attentions for optoelectronic applications due to their unique electronic properties. In this paper, we first present an overview on the techniques of fabrication for III-nitride-based QDs. Then various optoelectronic devices such as QD lasers, QD light-emitting diodes(LEDs), QD infrared photodetectors(QDIPs) and QD intermediate band(QDIB) solar cells(SCs) are discussed. Finally, we focus on the future research directions and how the challenges can be overcome.

关键词： III-nitride-based quantum dots Lasers Light-emitting diods Infrared photodetectors Solar cells

Standards and methods for dent assessment and failure prediction of pipelines:A critical review

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Petroleum Science 2022年第6期19卷 3029-3045页

作者： Jian Zhao yun-Rong lv y.Frank Cheng Dept.of Mechanical&Manufacturing Engineering University of CalgaryAlbertaT2N 1N4Canada Guangdong Provincial Engineering Technology Research Center of Petrochemical Corrosion and Safety Guangdong University of Petrochemical TechnologyMaomingGuangdongChina

Dent,a common mechanical damage on pipelines,is associated with a significant local plastic *** can cause pipeline failures,especially when they are combined with other types of defects such as gouges,fatigue,corrosion,and *** this work,a systematic review of various assessment methods and standards for pipeline dents,including the combination of a dent with other defects,is ***,the methods available today are not sufficiently accurate and reliable to assess pipeline dents,especially the dent-defect *** plain dents on pipelines,both the depthbased criterion and the strain-based criterion are commonly used in *** main problems include inaccuracy and *** a dent combined with other defects,the existing assessment techniques are not mature enough to give reliable *** experimental testing and numerical modeling through finite element(FE)analysis are capable of investigating the influence of dents and dent-defect combinations on burst failure pressure of the pipelines,although an approximation to the reality is still the main difficulty existing in the experimental testing and FE ***,relevant studies on assessment techniques for plain dents,a dent with fatigue and a dent with a single gouge have been common in *** combinations of a dent with corrosion or cracks have been rarely assessed due to complicated mechanisms involving a multi-physics coupling *** of novel assessment methods by integrating mechanical stress and strain,electrochemical reactions and steel metallurgy will be a key topic to accurately assess the dent-defect combinations for improved pipeline integrity.

关键词： Dents Pipelines Assessment techniques Burst failure pressure Dent-defect combinations

The role of melt cooling rate on the interface between 18R and Mg matrix in Mg_(97)Zn_(1)y_(2) alloys

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Journal of Magnesium and Alloys 2023年第8期11卷 2883-2890页

作者： Q.Q.Jin x.H.Shao J.M.Li Z.Z.Peng M.lv B.Zhang y.M.Li x.L.Ma Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Hebei University of Science and TechnologyShijiazhuangHebei 050018China

The role of melt cooling rate on the interface morphology and dislocation configuration between 18R long-period stacking ordered(LPSO)structure and Mg matrix in Mg_(97)Zn_(1)y_(2)(at.%)alloys was investigated by atomic-scale HAADF-STEM *** 18R/Mg interface is step-like both in the near-equilibrium alloy and non-equilibrium *** cooling rate makes the step size more regular and *** 54R structure can be observed at the interface in the near-equilibrium alloy,and the dislocations are highly ordered.54R and 54R′structure sandwiched by b1 and b2+b3 dislocation arrays,and new dislocation configuration can be detected at the interface in the non-equilibrium alloy,but the dislocations are less ordered.18R/Mg interface containing 54R or 54R′in equilibrium width,parallel to the(010)plane,should be most stable based on elastic *** segregation of solute atoms and its strong interaction with dislocations dominate the LPSO/Mg interface via diffusion-displacive transformation.

关键词： Magnesium alloys Long-period stacking ordered phases Dislocations Interface structure