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Transient growth in Poiseuille-Rayleigh-Bénard flows of binary fluids with Soret effect

Applied Mathematics and Mechanics(English Edition) 2016年第9期37卷 1203-1218页

作者： Jun hU d.hENRY h.BENhAdId Xieyuan YIN Institute of Applied Physics and Computational Mathematics Beijing 100088China Laboratoire de Mecanique des Fluides et d'Acoustique CNRS/Universitd de LyonEcole Centrale de Lyon/universite Lyon 1/INSA de LyonECL36 avenue Guy de Collongue69134 Ecully CedexFrance department of Modern Mechanics University of Science and Technology of ChinaHefei 230027China

The transient growth due to non-normMity is investigated for the Poiseuille- Rayleigh-Benard problem of binary fluids with the Soret effect. For negative separation factors such as ψ = -0.1, it is found that a large transient growth can be obtained by the non-normal interaction of the two least-stable-modes, i.e., the upstream and downstream modes, which determine the linear critical boundary curves for small Reynolds numbers. The transient growth is so strong that the optimal energy amplification factor G（t） is up to 10^2 - 10^3. While for positive separation factors such as ψ = 0.1, the transient growth is weak with the order O（I） of the amplification factor, which can even be computed by the least-stable-mode. however, for both cases, the least-stable-mode can govern the long-term behavior of the amplification factor for large time. The results also show that large Reynolds numbers have stabilization effects for the maximum amplification within moderate wave number regions. Meanwhile, much small negative or large positive separation factors and large Rayleigh numbers can enlarge the maximum transient growth of the pure streamwise disturbance with the wavenumber α= 3.14. Moreover, the initial and evolutionary two-dimensional spatial patterns of the large transient growth for the pure streamwise disturbance are exhibited with a plot of the velocity vector, spanwise vorticity, temperature, and concentration field. The initial three-layer cell vorticity struc- ture is revealed. When the amplification factor reaches the maximum Gmax, it develops into one cell structure with large amplification for the vorticity strength.

关键词： binary fluid Soret effect transient growth Poiseuille-Rayleigh-Benard flow

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On the formation of shear bands in a metallic glass under tailored complex stress fields

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Journal of Materials Science & Technology 2020年第18期52卷 112-117页

作者： S.h.Chen T.Li W.J.Chang h.d.Yang J.C.Zhang h.h.Tang S.d.Feng F.F.Wu Y.C Wu School of Mechanical Engineering Hefei University of TechnologyHefei 230009China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China School of Materials Science and Engineering Liaoning University of TechnologyJinzhou 121001China School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China

The formation of shear bands in metallic glasses(MGs)was examined by tailoring localized complex stress fields(LCSFs).The findings have shown that the LCSFs in MGs can increase the localization of strained atoms and accelerate the release of accumulated deformation energy for initiating a shear band in confined and thin-layered *** findings not only add more knowledge to the formation mechanisms of shear bands in MGs,but also provide possible rationale for the discrepancies in the mechanical properties of different-sized *** compared with the bulk samples,the higher strength and larger elastic limits in nanoscaled MGs could be attributed to the elimination of stress-concentrators,which can serve as LCSFs.

关键词： Localized complex stress field Shear band Metallic glass Molecular dynamics simulation Size effect

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LIVING/CONTROLLEd GRAFTING FROM POLYMER MICROSPhERES

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Chinese Journal of Polymer Science 2003年第6期21卷 639-651页

作者： harald d. h. Stver dept. of Chemistry McMaster University Hamilton ON L8S 4MI Canada

A review is given of grafting-from methods using living polymerizations, with emphasis on grafting from polymermicrospheres using ATRP.

关键词： Living controlled polymerization Grafting ATRP Microspheres

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Fractional delay compensated discrete-time SMC for networked control system

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digital Communications and Networks 2017年第2期3卷 112-117页

作者： d.h. Shah A.J. Mehta Gujarat Technological University Gujarat India Institute of Infrastructure Technology Research and Management Gujarat India

Time-varying network induced delay in the communication channel severely affects the performance of closed loop network control systems. In this paper, a novel idea of compensating the fractional time varying communication delay in the sliding Surface is presented. The fractional time delay in the sensor to controller and controller to actuator channel is approximated using the Thiran approximation technique to design the sliding surface. A discrete-time sliding mode control law is derived using the proposed surface that compensates fractional time delay in sensor to controller and controller to actuator channels for uncertain network control systems. The sufficient condition for closed loop stability of the system is derived using the Lyapunov function. The efficacy of the proposed strategy is supported by the simulation results.

关键词： discrete-time sliding mode control Networked control Network delay

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Microstructural evolution and mechanical properties of Mg-9.8Gd-2.7Y-0.4Zr alloy produced by repetitive upsetting

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Journal of Materials Science & Technology 2018年第7期34卷 1067-1075页

作者： h.Zhou h.Y.Ning X.L.Ma d.d.Yin L.R.Xiao X.C.Sha Y.d.Yu Q.d.Wang Y.S.Li Nano and heterogeneous Materials Center School of Materials and EngineeringNanjing University of Science and TechnologyNanjing210094China Institute of Microstructure and Property of Advanced Materials Beijing University of TechnologyBeijing 100124China School of Mechanical and Electrical Engineering Heilongjiang Institute of TechnologyHeilongjiang 150050China School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040China department of Materials Science&Engineering North Carolina State UniversityRaleighNC 27695USA Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengduSichuan 610031China National Engineering Research Center of Light Alloys Net Forming and State Key Laboratory of Metal Matrix CompositeShanghai Jiao Tong University200240 ShanghaiChina

A newly developed severe plastic deformation （SPd） technique, i.e. repetitive upsetting （RU）, is employed to improve the strength and ductility of a Mg-Gd-Y-Zr alloy. during the RU processing, dynamic recrystallization occurs in the Mg alloy, which leads to a significant grain refinement from 11.2 p.m to 2.8 μm. The yield strength （YS）, ultimate tensile strength （UTS） and elongation increase simultaneously with increasing RU passes. The microstructural evolution is affected by processing temperatures. dynamic recrystallization prevails at low temperatures, while dynamic recovery is the main effect factor at high temperatures. Texture characteristics gradually become random during multiple passes of RU processing, which reduces the tension-compression asymmetry of the Mg-Gd-Y-Zr alloy. 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

关键词： Severe plastic deformation (SPd) Repetitive upsetting (RU) Mg-RE alloy Mechanical properties

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PREdICTION OF ThE MIXING ENThALPIES OF BINARY LIQUId ALLOYS BY MOLECULAR INTERACTION VOLUME MOdEL

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Acta Metallurgica Sinica(English Letters) 2008年第5期21卷 336-340页

作者： h.W. Yang d.P. Tao Z.h. Zhou Faculty of Materials and Metallurgical Engineering Kunming University of Science and Technology Kunming 650093 China

The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model （MIVM）, which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted va... 详细信息

关键词： Molecular interaction volume model Mixing enthalpy Liquid alloys Prediction

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A continuum traffic flow model with the consideration of coupling effect for two-lane freeways

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Acta Mechanica Sinica 2011年第2期27卷 228-236页

作者： d.-h. Sun G.-h. Peng L.-P. Fu h.-P. he College of Automation Chongqing University400030 Chongqing China department of Civil & Environmental Engineering University of Waterloo Waterloo Ontario N2L 3G 1 Canada College of Automation Chongqing University 400030 Chongqing China

A new higher-order continuum model is proposed by considering the coupling and lane changing effects of the vehicles on two adjacent lanes. A stability analysis of the proposed model provides the conditions that ensure its linear stability. Issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are also investigated with numerical experiments. The simulation results show that the proposed model is capable of providing explanations to some particular traffic phenomena commonly observable in real traffic flows.

关键词： Two-lane traffic Two delay time scales model Numerical simulation Coupling effect Phase transition

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Fabrication of SAW Sensor for detecting Chemical Agent

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稀有金属材料与工程 2006年第A3期35卷 433-435页

作者： J h Lee B S Joo J S huh d d Lee School of Electronic & Electrical Engineering Kyungpook National UniversityKorea dept.of Materials Science and Metallurgy Kyungpook National UniversityKorea

SAW sensors using five different types of polymer to detect of chemical agents(dMMP,Ch_3CN,Ch_2Cl_2,dCP) have been fabricated and its gas response characteristics were extensively *** polymers used as the sensing material are polyisobutylene(PIB),polyepichlorohydrin(PECh),polydimethylsiloxane(PdMS),polyisoprene(PIP)and polybutadiene(PBd).Their thin films were coated on quartz substrate by spin coating *** types of simulants gases,dimethylmethylphosphonate(dMMP),acetonitrile(Ch_3CN)and dichloromethane(Ch_2Cl_2),dichloropentane(dCP)were used as target gases,instead of the real nerve,blood,choking and vesicant *** spin coating of PIB and PECh,the substrates were heated to 65℃with N_2 flow for 1 h to remove the cyclohexane and ethylacetate which was used as solvent. PdMS was heated to 75℃with N_2 flow for 2 h to remove the ethylacetate which was used as *** and PIP on the substrate were heated to 60℃with N_2 flow for 1 h to remove the benzen which was used as *** sensing characteristics of the SAW sensors were measured by using E-5061A network analyzer.

关键词： SAW dMMP Ch3CN Ch2Cl2 dCP polymer film

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Recoil polarimetry in meson photoproduction at MAMI

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Chinese Physics C 2009年第12期33卷 1373-1376页

作者： M.h. Sikora d.I. Glazier d.P. Watts University of Edinburgh King’s Buildings Edinburgh EH9 3JZ United Kingdom

The nucleon excitation spectrum remains poorly known, with the masses, widths, EM couplings and even existence of many states not well established. A program of experiments using meson photoproduction off the nucleon is being carried out to improve this situation. A new large acceptance recoil polarimeter has been developed by the Edinburgh group for use in such reactions with the Crystal Ball at MAMI. This work summarizes the procedure used to measure recoil polarization with the new device and presents some preliminary results for the double polarization observable Cx in the reaction γp→pπ, compared to the current partial wave analysis.

关键词： polarimeter meson photoproduction polarization observable recoil

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Recent progress in fatigue behavior of Mg alloys in air and aqueous media: A review

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Journal of Materials Science & Technology 2017年第10期33卷 1075-1086页

作者： B.J.Wang S.d.Wang d.K.Xu E.h.han School of Environmental and Chemical Engineering Shenyang Ligong University CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences

due to the interactions between mechanics and chemistry, Mg alloys are inevitably subjected to the combined effect of corrosion attack and cyclic loading, which eventually leads to corrosion fatigue failure. In this paper, fundamental aspects regarding the fatigue behavior of Mg alloys have been reviewed,including：（1） fatigue behavior of Mg alloys in air and aqueous media; and（2） the influence of microstructure, anodic dissolution, hydrogen embrittlement（hE）, heat treatment and surface protection on fatigue behavior of Mg alloys. Moreover, some remaining unresolved issues and future targets to deeply understand the failure mechanism of corrosion fatigue have been described.

关键词： Magnesium alloys Fatigue Corrosion fatigue Crack initiation hydrogen embrittlement

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