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Science China(Technological Sciences) 2020年第10期63卷 2163-2168页

作者： WANG Qian LIU HeCong LIU XunChen WANG SiRui FU Chen WANG GuoQing GAO Yi CAI WeiWei QI Fei key laboratory of Education Ministry for Power Machinery and Engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China state key laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200241China

Optical combustion diagnostics are indispensable tools to investigate flame dynamics and excavate in-situ quantities of flames,such as velocity,temperature,concentration of key intermediates and pressure without introducing probe *** example,velocity and flame temperature can be obtained using techniques such as particle image velocimetry,coherent anti-Stokes Raman scattering spectroscopy,Rayleigh scattering and tunable diode laser absorption spectroscopy,respectively.

关键词： scattering laser concentration

Thickness-Dependent Microstructure and its Effect on Anisotropic mechanical Properties of Duplex Stainless Steel 2205 Multi-pass Welded Joints

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Acta Metallurgica Sinica(English Letters) 2023年第11期36卷 1883-1892页

作者： Zhilong Dong Xue-Fang Xie Jingwen Li Yu Wan state key laboratory of Heavy Oil Processing College of New EnergyChina University of Petroleum(East China)Qingdao266580China China National Offshore Oil Corporation Petrochemical Engineering Company Limited Jinan250000China

In this study,the thickness-dependent microstructural characteristics of duplex stainless steel 2205 multi-pass welded joints were first investigated by the combination of optical microscope and electron back-scattered diffraction ***,a series of tensile tests of miniature samples cut from different passes and directions were performed to analyze the thickness-dependent and anisotropic mechanical *** results demonstrate that the microstructure changed with the welded passes,i.e.,a large number of grain boundary austenite,Widmanstätten austenite and a small number of tiny intragranular austenite existed at the surface passes,while a mass of intragranular austenite were found at the middle ***,the Kurdjumov–Sachs orientation relationship was widespread at the welded *** addition,the yield and tensile strengths of the middle passes were greater than that of the surface passes due to the grain-boundary strengthening by tiny intragranular ***,due to the existence of Kurdjumov–Sachs orientation relationship,the longitudinal yield and tensile strength were greater than transverse values,particularly for the middle passes.

关键词： Duplex stainless steel Multi-pass welded joints Thickness-dependent microstructure Anisotropic mechanical properties

Fe-B-Y-Nb bulk metallic glasses in relation to clusters

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Science China(Physics,Mechanics & Astronomy) 2008年第4期51卷 421-426页

作者： CHENG Xu WANG Qing CHEN WeiRong DONG Chuang state key laboratory of Materials Modification Dalian University of TechnologyDalian 116024China Department of mechanical Engineering Dalian UniversityDalian 116622China

Bulk metallic glass formations in the Fe-B-Y-Nb quaternary alloy system were in-vestigated by using the cluster line rule in combination with the minor alloying principle. The Fe-B-Y ternary system was selected as the basic system and the intersections of cluster lines were taken as the basic ternary compositions. The basic compositions were further alloyed with minor amounts of Nb. After 3-5 at.% Nb was added,the basic composition Fe68.6B25.7Y5.7,which was developed from the most densely packed cluster Fe8B3,formed 3 mm bulk metallic glasses. These quaternary bulk metallic glasses (Fe68.6B25.7Y5.7)100-xNbx (x=3-5 at.%) are expressed approximately with a unified simple composition formula: (Fe8B3)1(Y,Nb)1. The (Fe68.6B25.7Y5.7)97Nb3 bulk metallic glass has the largest glass forming ability with the following characteristic parameters Tg=907 K,Tx=1006 K,Tg/Tl=0.644,γ=0.434,and longness t=22 mm. The combination of the cluster line rule and the minor-alloying principle is a promising new route towards the quantitative composition design of multi-component metallic glasses.

关键词： bulk metallic glass Fe-B-Y-Nb alloys cluster composition design

Entropic pressure between fluctuating membranes in multilayer systems

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Science China(Physics,Mechanics & Astronomy) 2018年第12期61卷 95-102页

作者： Long Li Xiaohuan Wang Yingfeng Shao Wei Li Fan Song state key laboratory of Nonlinear Mechanics (LNM) and Beijing key laboratory of Engineered Construction and Mechanobiology Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences School of mechanical and Electrical Engineering North China Institute of Aerospace Engineering

Gaining insights into the fluctuation-induced entropic pressure between membranes that mediates cell adhesion and signal transduction is of great significance for understanding numerous physiological processes driven by intercellular *** much effort has been directed toward investigating this entropic pressure,there still exists tremendous controversy regarding its quantitative nature,which is of primary interest in biophysics,since Freund challenged the Helfrich’s well-accepted results on the distance *** this paper,we have investigated the entropic pressure between fluctuating membranes in multilayer systems under pressure and tension through theoretical analysis and Monte Carlo *** find that the scaling relations associated with entropic pressure depend strongly on the magnitude of the external pressures in both bending rigidityand surface tension-dominated *** particular,both theoretical and computational results consistently demonstrate that,in agreement with Helfrich,the entropic pressure p decays with inter-membrane separations c as p^c^(–3)for the tensionless multilayer systems confined by small external ***,our results suggest that the entropic pressure law follows to be p^c^(–1)and p^c^(–3),respectively,in the limit of large and small thermal wavelengths for bending fluctuations of the membranes in a tensionindependent manner for the case of large external pressures.

关键词： entropic pressure fluctuating membranes statistical mechanics theory Monte Carlo simulation cell adhesion

Bifurcation\instability forms of high speed railway vehicles

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Science China(Technological Sciences) 2013年第7期56卷 1685-1696页

作者： DONG Hao ZENG Jing XIE JianHua JIA Lu state key laboratory of Traction Power Southwest Jiaotong University Department of mechanical Engineering Southwest Jiaotong University Emei Campus of Southwest Jiaotong University

The China high speed railway vehicles of type CRH2 and type CRH3, modeled on Japanese high speed Electric Multiple Units (EMU) E2 series and Euro high speed EMU ICE3 series possess different stability behaviors due to the different matching re-lations between bogie parameters and wheel profiles. It is known from the field tests and roller rig tests that, the former has a higher critical speed while large limit cycle oscillation appears if instability occurs, and the latter has lower critical speed while small limit cycle appears if instability occurs. The dynamic model of the vehicle system including a semi-carbody and a bogie is established in this paper. The bifurcation diagrams of the two types of high speed vehicles are extensively studied. By using the method of normal form of Hopf bifurcation, it is found that the subcritical and supercritical bifurcations exist in the two types of vehicle systems. The influence of parameter variation on the exported function Rec1(0) in Hopf normal form is studied and numerical shooting method is also used for mutual verification. Furthermore, the bifurcation situation, subcritical or supercritical, is also discussed. The study shows that the sign of Re(λ) determinates the stability of linear system, and the sign of Rec1(0) determines the property of Hopf bifurcation with Rec1(0)>0 for supercritical and Rec1(0)<0 for subcritical.

关键词： high speed vehicle bifurcation critical speed limit cycle normal form

Enlightenment from the COVID-19 Pandemic:The Roles of Environmental Factors in Future Public Health Emergency Response

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Engineering 2022年第1期8卷 108-115页

作者： Xiaolei Wang Fengchang Wu Xiaoli Zhao Xiao Zhang Junyu Wang Lin Niu Weigang Liang Kenneth Mei Yee Leung John P.Giesy state key laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China state key laboratory of Marine Pollution&Department of Chemistry City University of Hong KongHong KongChina Department of Veterinary Biomedical Sciences and Toxicology Centre University of SaskatchewanSaskatoonSK S7N 5E2Canada Department of Environmental Sciences Baylor UniversityWacoTX 76798USA

The coronavirus disease 2019(COVID-19)pandemic is challenging the current public health emergency response systems(PHERSs)of many *** environmental factors,such as those influencing the survival of viruses and their transmission between species including humans,play important roles in PHERSs,little attention has been given to these *** study describes and elucidates the roles of environmental factors in future *** improve countries’capability to respond to public health emergencies associated with viral infections such as the COVID-19 pandemic,a number of environmental factors should be considered before,during,and after the responses to such *** specifically,to prevent pandemic outbreaks,we should strengthen environmental and wildlife protection,conduct detailed viral surveillance in animals and hotspots,and improve early-warning *** the pandemic,we must study the impacts of environmental factors on viral behaviors,develop control measures to minimize secondary environmental risks,and conduct timely assessments of viral risks and secondary environmental effects with a view to reducing the impacts of the pandemic on human health and on *** the pandemic,we should further strengthen surveillance for viruses and the prevention of viral spread,maintain control measures for minimizing secondary environmental risks,develop our capability to scientifically predict pandemics and resurgences,and prepare for the next unexpected ***,we should restore the normal life and production of the public based on the“One Health”concept,that views global human and environmental health as inextricably *** recommendations are essential for improving nations’capability to respond to global public health emergencies.

关键词： Public health emergency Public health emergency response system Environmental factors Prevention and control Viral infections

Elastic Modulus Prediction of Three-dimension-4 Directional Braided C_f/SiC Composite Based on Double-scale Model

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Journal of Wuhan University of Technology(Materials Science) 2015年第3期30卷 500-508页

作者：牛序铭 SUN Zhigang KONG Chunyuan 宋迎东 Jiangsu Province key laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics state key laboratory of Mechanics and Control mechanical Structures College of Energy and Power Nanjing University of Aeronautics & Astronautics

Double-scale model for three-dimension-4 directional（3D-4d） braided C/SiC composites has been proposed to investigate its elastic properties. The double-scale model involves micro-scale that takes fiber/ matrix/porosity in fibers tows into consideration with unit cell which considers the 3D-4d braiding structure. Micro-optical photographs of composites have been taken to study the braided structure. Then a parameterized finite element model that reflects the structure of 3D-4d braided composites is proposed. Double-scale elastic modulus prediction model is developed to predict the elastic properties of 3D-4d braided C/SiC composites. Stiffness and eompliance-averaging method and energy method are adopted to predict the elastic properties of composites. Static-tension experiments have been conducted to investigate the elastic modulus of 3D-4d braided C/SiC composites. Finally, the effect of micro-porosity in fibers tows on the elastic modulus of 3D-4d braided C/SiC composites has been studied. According to the conclusion of this thesis, elastic modulus predicted by energy method and stiffness-averaging method both find good agreement with the experimental values, when taking the micro-porosity in fibers tows into consideration. Differences between the theoretical and experimental values become smaller.

关键词： 3D-4d braided C/SiC composites double-scale model elastic modulus energy methodstiffness and compliance-averaging method porosity ratio

Multi-dimple phenomena in TEHL point contacts

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Science China Chemistry 2002年第2期45卷 127-134页

作者：杨沛然 KANETA Motohiro state key laboratory of Tribology Tsinghua University Beijing 100084 China Department of mechanical Engineering Qingdao Institute of Architecture and Engineering Qingdao 266033 China

Theoretical analysis and experimental measurement of the multiple dimples in thermal elastohydrodynamic lubrication (TEHL) point contacts have been carried out. Good agreement is found between the theoretical and expe... 详细信息

关键词： multi-dimple, point contact, temperature, elastohydrodynamic lubrication.

A 3D microseismic data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions and its application

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第4期15卷 911-925页

作者： Jingren Zhou Jinfu Lou Jiong Wei Feng Dai Jiankang Chen Minsi Zhang state key laboratory of Hydraulics and Mountain River Engineering College of Water Resources and HydropowerSichuan UniversityChengdu610065China CCTEG Coal Mining Research Institute Beijing100013China state key laboratory of Coal Mining and Clean Utilization China Coal Research InstituteBeijing100013China Department of Engineering Mechanics Tsinghua UniversityBeijing100084China School of Civil and Architecture Engineering East China University of TechnologyNanchang330013China

Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure ***,the properties of rock mass change in time and space due to mining-induced ***,it is always challenging to accurately measure rock mass *** this study,a three-dimensional(3D)microseismic(MS)data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is *** is a 3D finite element model that takes seepage,damage and stress field effects into account *** factors(***,water and microseismicity)are used to optimize the rock mass mechanical parameters at different *** model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground *** is found that the damage pattern is mostly controlled by the structure,water and rock mass *** damage pattern is evidently different from the two-dimensional result and is more consistent with the field *** difference is caused by the MS-derived damage acting on the rock *** data are responsible for gradually correcting the damage zone,changing the direction in which it expands,and promoting it to evolve close to *** the crown pillar,the proposed model yields a more trustworthy safety *** order to guarantee the stability of the pillar,it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.

关键词： Microseismic monitoring Numerical simulation Rock damage Jointed rock mass Hydro-mechanical coupling

Fabrication of Microlens Array and Its Application:A Review

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Chinese Journal of mechanical Engineering 2018年第1期31卷 10-18页

作者： Wei Yuan Li-Hua Li Wing-Bun Lee Chang-Yuen Chan state key laboratory of Ultra-precision Machining Technology Partner Laboratory in the Hong Kong Polytechnic University Shenzhen Branch of state key laboratory of Ultra-precision Machining Technology PolyU Shenzhen Research Institute

Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.

关键词： Microlens array Ultraprecision machining 3D image system MEMS