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Nonlinear static and dynamic responses of an electrically actuated viscoelastic microbeam

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Acta Mechanica Sinica 2009年第2期25卷 211-218页

作者： Y.M.Fu j.zhang College of Mechanics and Aerospace Hunan University

On the basis of the Euler-Bernoulli hypothesis, nonlinear static and dynamic responses of a viscoelastic microbeam under two kinds of electric forces [a purely direct current （DC） and a combined current composed of a DC and an alternating current] are studied. By using Taylor series expansion, a governing equation of nonlinear integro-differential type is derived, and numerical analyses are performed. When a purely DC is applied, there exist an instantaneous pull-in voltage and a durable pull-in voltage of which the physical meanings are also given, whereas under an applied combined current, the effect of the element relaxation coefficient on the dynamic pull-in phenomenon is observed where the largest Lyapunov exponent is taken as a criterion for the dynamic pull-in instability of viscoelastic microbeams.

关键词： MEMS Viscoelastic microbeam Nonlineardynamics

Microstructure and brazing mechanism of porous Si_3N_4/Invar joint brazed with Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler

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journal of Materials Science & Technology 2018年第4期34卷 713-719页

作者： j.zhang j.Y.Liu T.P.Wang School of Materials Science and Engineering Harbin Institute of Technology

Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. The typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/TiN ＋ Ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer ＋ diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength （73 MPa） was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-Ti brazing alloy and had reached 86% of the ceramic. The release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2Ti and Ni3Ti intermetallics played the major role in the improvement of joint strength.

关键词： Porous Si3N4 Invar alloy Brazing Microstructure Mechanical properties

Ground-based and additional science support for SMILE

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Earth and Planetary Physics 2024年第1期8卷 275-298页

作者： j.A.Carter M.Dunlop C.Forsyth K.Oksavik E.Donovon A.Kavanagh S.E.Milan T.Sergienko R.C.Fear D.G.Sibeck M.Connors T.Yeoman X.Tan M.G.G.T.Taylor K.McWilliams j.Gjerloev R.Barnes D.D.Billet G.Chisham A.Dimmock M.P.Freeman D.-S.Han M.D.Hartinger S.-Y.W.Hsieh Z.-j.Hu M.K.james L.juusola K.Kauristie E.A.Kronberg M.Lester j.Manuel j.Matzka I.McCrea Y.Miyoshi j.Rae L.Ren F.Sigernes E.Spanswick K.Sterne A.Steuwer T.Sun M.-T.Walach B.Walsh C.Wang j.Weygand j.Wild j.Yan j.zhang Q.-H.zhang Planetary Sciences Group School of Physics and AstronomyUniversity of LeicesterUniversity RoadLeicesterLE17RHUK Rutherford Appleton Laboratory Space Science Technology Facilities CouncilOxfordshireUK School of Space and Environment Beihang UniversityBeijing 100191China Key Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100017China Department of Space and Climate Physics UCLMullard Space Science LaboratoryHolmbury St.MaryDorkingSurreyRH56NTUK Birkeland Centre for Space Science Department of Physics and Technology.University of BergenBergenNorway Department of Physics and Astronomy University of Calgary2500 University DriveCalgaryAlbertaCanada T2N 1N4 British Antarctic Survey CambridgeUK Swedish Institute of Space Physics KirunaSweden West Highfield Campus University of SouthamptonUniversity RoadSO171BJUK Goddard Space Flight Center NASAGreenbeltMarylandUSA Athabasca University AthabascaCanada ESTEC European Space AgencyNetherlands University of Saskatchewan SaskatoonCanada The johns Hopkins University Applied Physics Laboratory LaurelMarylandUSA Swedish Institude of Space Physics UppsalaSE 75121Sweden Tongji University Shanghai 200092China Center for Space Plasma Physics Space Science Institute4765 Walnut Street Suite BBoulderColorado80301USA Polar Research Institute of China Shanghai 200136China Finnish Meteorological Institute(FMI) Finland Department of Earth and Environmental Sciences(Geophysics) Ludwig Maximilian University of Munich(LMU)MunichTheresienstr.41MunichD-80333Germany Canadian Space Agency MontrealCanada GFZ German Research Centre for Geosciences PotsdamGermany Nagoya University Institute for Space Earth Environment ResearchCenter for Integrated Data ScienceNagoyaAichiJP 464-8601 Northumbria University Newcastle upon TyneTyne and WearUK NE18ST National Space Science Center Chinese Academy SciencesBeijing 100190China Arctic Geophysics University Centre in Svalbard

The joint European Space Agency and Chinese Academy of Sciences Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will explore global dynamics of the magnetosphere under varying solar wind and interplanetary magnetic field conditions,and simultaneously monitor the auroral response of the Northern Hemisphere *** these large-scale responses with medium and fine-scale measurements at a variety of cadences by additional ground-based and space-based instruments will enable a much greater scientific impact beyond the original goals of the SMILE ***,we describe current community efforts to prepare for SMILE,and the benefits and context various experiments that have explicitly expressed support for SMILE can offer.A dedicated group of international scientists representing many different experiment types and geographical locations,the Ground-based and Additional Science Working Group,is facilitating these *** include constructing an online SMILE Data Fusion Facility,the discussion of particular or special modes for experiments such as coherent and incoherent scatter radar,and the consideration of particular observing strategies and spacecraft *** anticipate growing interest and community engagement with the SMILE mission,and we welcome novel ideas and insights from the solar-terrestrial community.

关键词： magnetosphere ionosphere magnetosphere-ionosphere coupling ground-based experimentation SMILE conjunctions missions

Molecular diffusion in ternary poly(vinyl alcohol)solutions

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Frontiers of Chemical Science and Engineering 2022年第6期16卷 1003-1016页

作者： Katarzyna Majerczak Ophelie Squillace Zhiwei Shi Zhanping zhang Zhenyu j.zhang School of Chemical Engineering University of BirminghamBirmingham B152TTUK The Procter and Gamble Company CincinnatiOH 45040USA

The diffusion kinetics of a molecular probe-rhodamine B-in ternary aqueous solutions containing poly(vinyl alcohol),glycerol,and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light *** show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical *** presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration,but significantly slows down the diffiision of rhodamine B above 3.9%(w/v)due to a dominating steric inhibition ***,introducing surfactants(cationic/nonionic/anionic)to the system results in a decreased diffusion coefficient of the molecular *** solutions containing nonionic surfactant,this can be explained by an increased crowding *** ternary poly(vinyl alcohol)solutions containing cationic or anionic surfactant,surfactant-polymer and surfactant-rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffiisivity of rhodamine *** results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds,and highlight the importance of selecting the appropriate additives and surfactants in formulated products.

关键词： fluorescence correlation spectroscopy poly(vinyl alcohol) anomalous diffusion crowding effects dynamic light scattering binding effects rhodamine B

Enhancing mechanical behavior of micaceous soil with jute fibers and lime additives

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journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1093-1100页

作者： j.zhang A.Deng M.jaksa School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaideSA5000Australia

Micaceous soils are common in many tropical countries and regions,and in some locations with moderate *** soils are spongy and unstable when loaded and are not considered suitable as construction material in earth *** resolve the issue,this work examined performance of micaceous soil reinforced with a combination of jute fibers,hydrated lime or slag-lime.A total of 28 sample sets were prepared at various *** compression tests were conducted on the samples cured for 7 d and 28 d,*** test results suggested that the unconfined compressive strength(UCS)and material stiffness were increased with the inclusion of up to 1%fiber and decreased if additional fibers were *** ductility was improved consistently with up to 1.5%fiber *** inclusions of fibers combined with hydrated lime or slag-lime further enhanced strength and stiffness of micaceous soil,and the improvement depended on the dosages *** the dosages examined,jute fibers outweighed lime and slag in gaining ductility,and the optimal fiber content was 1%where strength and ductility were considered.

关键词： Geosynthetics jute fiber Unconfined compressive strength(UCS) Stiffness

Optimizing micaceous soil stabilization using response surface method

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journal of Rock Mechanics and Geotechnical Engineering 2021年第1期13卷 212-220页

作者： j.zhang A.Deng M.jaksa School of Civil Environmental and Mining EngineeringUniversity of AdelaideAdelaideSA 5000Australia

Micaceous soil is a problematic soil due to its low strength and poor *** this context,the performances of micaceous soils were improved by applying a combination of granulated blast furnace slag,fiber and polymer *** dosages examined included 0%e30%mica,3%e15%slag and 0.25%e1.25%fiber by weight,and 0.1e0.5 g/L polymer *** of the combinations were found to increase the material strength and ductility,yet to be *** refine the dosage,response surface method was used to conduct experimental design and develop predictive models for material *** developed models formulate the material strength as a nonlinear function of dosages and,by interrogating it,can optimize additive contents in terms of target *** models were verified through trials and can be used to determine dosages to upscale micaceous soils to field conditions.

关键词： Fiber Polymer Central composite design Unconfined compression strength(UCS) Mica

HIGH-TEMPERATURE TENSILE FRACTURE BEHAVIOR OF DIRECTIONALLY SOLIDIFIED Ni,Cr,Al-TaC EUTECTIC SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 455-459页

作者： j.zhang j.j.Yu H.Z.Fu State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072ChinaInstitute of Metal Research Chinese Academy of Sciences Shenyang 110016 ChinaState Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072China

The high-temperature tensile fracture behavior of the Ni, Cr, Al-TaC eutectic superal-loy directionally solidified under high temperature gradient is investigated. The high-temperature tensile fracture of this in situ composite has ductile character with lots of ductile nests whose diameters decrease with the increasing solidification rates. The maximum σb and δ are respectively 668.5MPa and 19.6%. There is α TaC whisker in the center of each nest, and the deformation of γ' and TaC is uneven. The high-temperature tensile behavior cannot be explained by the rule of mixtures but is decided by the formation of the plastic deformation band. The crack extension model is given.

关键词： Ni Cr Al-TaC eutectic superalloy directional solidification,in situ composite high-temperature tenslie fracture

支架特异性脂肪衰减指数与PCI术后靶血管血运重建相关

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国际医学放射学杂志 2024年第2期 251-252页

作者： F.Xu C.C.Wang Q.Tao j.zhang M.M.Zhao S.W.Shi 潘红利

摘要目的探讨支架特异性血管周围脂肪衰减指数（FAI）在支架植入病人中的临床相关性。方法回顾性纳入162例在支架植入后接受连续冠状动脉CT血管成像

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Turbulent mechanisms in open channel sediment-laden flows

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International journal of Sediment Research 2019年第6期34卷 550-563页

作者： Hai Huang Hongwu zhang Deyu Zhong Yinglong j.zhang State Key Laboratory of Hydroscience and Engineering Tsinghua Univ. State Key Laboratory of Plateau Ecology and Agriculture Qinghai University Virginia Institute of Marine Science College of William & MaryCenter for Coastal Resource Management

The effects of turbulence on water-sediment mixtures is a critical issue in studying sediment-laden *** sediment concentrations and particle inertia play a significant role in the effects of turbulence on mixtures.A two-phase mixture turbulence model was applied to investigate the turbulence mechanisms affecting sediment-laden *** two-phase mixture turbulence model takes into account the complicated mechanisms arising from interphase transfer of turbulent kinetic energy,particle collisions,and *** turbulence in sediment-laden flows is the result of the interaction of four factors,*** production,dissipation,diffusion,and inter-phase transfer of turbulent kinetic energy of *** turbulence production and dissipation are two dominant processes which balance the turbulent kinetic energy of *** turbulence production represents turbulence intensity,while the inter-phase transfer of turbulent kinetic energy denotes the effect of particles on the turbulence of sediment-laden ***,the magnitude of the inter-phase interaction term is much less than that of the turbulence production and dissipation terms,due to an approximate local balance between production and dissipation of the turbulent kinetic energy,even the small order of the inter-phase interaction has a significant impact on the turbulent balance of sediment-laden *** presence of particles plays a duel role in the turbulence dissipation of mixtures:both promotion and *** important parameter used to determine the turbulent viscosity of mixtures,which is constant in clear water,is the function of the sediment concentration and particle inertia in sediment-laden flows.

关键词： Turbulence modulation Two-phase mixture turbulence model Suspended sediment Open channels