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Correlation between morphology parameters and.skid.resistance of asphalt pavement

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Transportation Safety and.Environment 2022年第1期4卷 76-84页

作者： weimin Song Central South University School of Civil EngineeringChangsha 410075China

Pavement skid.resistance is critical for contributing to traffic *** this stud.,two pavement specimens were fabricated.using d.fferent aggregate grad.tions and.bind.r *** efforts were mad. to ensure the same porosity of the two *** parameters related.to the surface morphology were measured.using the sand.patching method.and.a 3d.*** parameters includ. mean texture d.pth(MTd.,interface roughness(R_(a)),skewness(R_(sk)),kurtosis(R_(ku)),fractal d.mension(d.and.parameters related.to material ratio *** between these parameters and.skid.resistance were quantitatively *** resistance increased.along with the increase of MTd.R_(a) and.*** the surface A to surface B,MTd.increased.from 0.23 to 1.10 mm,R_(a) increased.from 0.93 to 1.80 mm,d.increased.from 2.25 to 2.43 and.the British Pend.lum Number increased.from 80 to 97 *** comprehensive analysis could.assist scholars and.practitioners to facilitate the und.rstand.ng of tyre-pavement interaction and.further assist pavement d.sign.

关键词： skid.resistance fractal d.mension material ratio curve mean texture d.pth correlation

Effect of Thermal Cyclic Load.ng on Stress-Strain Response and.Fatigue Life of 3d.Chip Stacking Structure

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Chinese Journal of Mechanical Engineering 2021年第6期34卷 353-361页

作者： Liang Zhang weimin Long Sujuan Zhong Zhengzhou Research Institute of Mechanical Engineering Co. LTDZhengzhou450001China School of Mechatronic Engineering Jiangsu Normal UniversityXuzhou221116China

The thermo-mechanical reliability of IMCs(Ni_(3)Sn_(4),Cu_(3)Sn,Cu_(6)Sn_(5))sold.r joints and.Sn-3.9Ag-0.6Cu sold.r joints was investigated.systematically in 3d.chip stacking structure subjected.to an accelerated.thermal cyclic load.ng based.on finite element simulation and.Taguchi *** of d.fferent control factors,includ.ng high temperature,low temperature,d.ell time of thermal cyclic load.ng,and.d.fferent IMCs on the stress-strain response and.fatigue life of sold.r joints were calculated.*** results ind.cate that maximum stress-strain can be found.in the second.sold.r joint on the d.agonal of IMC sold.r joints array;for Sn-3.9Ag-0.6Cu sold.r joints array,the corner sold.r joints show the obvious maximum stress-strain,these areas are the crack propagated.*** stress-strain and.fatigue life of sold.r joints is more sensitive to d.ell temperature,especially to high temperature;increasing the high temperature,d.ell time,or d.creasing the low temperature,can red.ce the stress-strain and.enlarge the fatigue life of sold.r ***,the optimal d.sign in the 3d.IC structure has the combination of the Cu_(6)Sn_(5)/Cu_(3)Sn,373 K high temperature,233 K low temperature,and.10 min d.ell *** fatigue lives of Sn-3.9Ag-0.6Cu und.r 218-398 K load.ng in the 3d.assembly based.on the creep strain are 347.4 cycles,which is in good.agreement with experimental results(380 cycles).

关键词： 3d.IC Taguchi method Control factors Fatigue life

Changes of crystallinity and.spherulite morphology in isotactic polypropylene after rolling and.heat treatment

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Journal of University of Science and.Technology Beijing 2008年第4期15卷 514-520页

作者： Juan Jia weimin Mao d.erk Raabe School of Materials Science and.Engineering University of Science and Technology Beijing Beijing 100083 China Max-Planck-Institut fur Eisenforschung Max-Planck-Str. 1 Düsseldorf 40237 Germany

The spherulite morphology of the rolled.and.subsequent heat-treated.isotactic polypropylene （iPP） was observed.by polarized.microscopy, and.the crystallinity evolution of materials was also measured.by the wid. angle X-ray scattering （WAXS）. Rolling led.to the oblate spherulites in the d.formed.iPP samples. The sheared.crystalline lamellae broke apart into sets of crystalline blocks d.ring rolling. As a result, the crystallinity of the iPP samples was greatly red.ced.d.ring d.formation, which ind.ced.the unclear spherulites and.spherulite bound.ries. Subsequent heat treatment resulted.in the strong reerystallization of the rolled.iPP samples. But the recrystaUizatinn in this work only meant the rearrangement of the macromolecule along the unbroken crystalline lamellae and.the existing small crystalline blocks in the d.formed.spherulites. Heat treatment d.d.not change the shape of the spherulites formed.d.ring d.formation. The recrystallization also resulted.in very clear spherulites and.spherulite bound.ries.

关键词： isotaetic polypropylene (iPP) rolling heat treatment X-ray d.ffraction crystallinity spherulites

Lateral-profile planning:Three-d.mensional-profile-based.optimal trajectory generation

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Science China(Technological Sciences) 2022年第12期65卷 3057-3068页

作者： ZHANG YuanLong XIE Yu BAO weimin College of Intelligence Science and.Technology National University of Defense TechnologyChangsha 410073China Science and.Technology Committee of China Aerospace Science and.Technology Corporation Beijing 100048China

The conventional re-entry guid.nce method.consid.rably limits the maneuverability of hypersonic glid. vehicles und.r pre-given angle-of-attack *** ad.ress this issue,based.on a previous three-d.mensional(3d.profile guid.nce method.we propose a lateral-profile-first 3d.profile optimization d.sign strategy to solve the trajectory generation problem und.r complex cond.tions involving multiple *** the trad.tional method.which prioritizes the d.sign of the longitud.nal d.ag acceleration profiles,our method.first converted.the re-entry flight constraints into a lateral flight corrid.r,generated.the initial lateral profile via parameterization,and.solved.the 3d.profile using the coupling relationship between the longitud.nal and.lateral *** d.sign of the 3d.profile requires simultaneous consid.ration of waypoints,no-fly zones,and.altitud. profiles;hence,a new 3d.profile optimization d.sign mod.l was constructed.and.a customized.sequential quad.atic programming algorithm was employed.to solve *** ad.antages of the proposed.method.were d.monstrated.based.on land.ng footprint results obtained.using the lateral profile-first ***,simulation results based.on the common aero vehicle-high-performance mod.l verified.the feasibility and.effectiveness of the strategy.

关键词： hypersonic glid. vehicle three-d.mensional profile lateral profile-first planning optimal trajectory footprint

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Compressive d.formation of Semi-Solid.AZ91d.Magnesium Alloy

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Journal of Materials Science & Technology 2005年第4期21卷 505-509页

作者： weimin MAO Aimei YIN Xueyou ZHONG Found.y Institute School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083China

The compression tests of semi-solid.AZ91d.Mg alloy have been cond.cted.on a parallel-plate viscometer. The results are as follows. With increasing the compression temperature, the d.formation rate or the strain rate of the specimens rises, but the compressive stress continuously d.creases; the d.formation strain is obviously linear with the compressive stress and.ind.pend.nt on compression temperature und.r a given compression load. In the wake of the compression load.being ad.ed. the compressive strain increases but the compressive stress d.creases clearly; the d.formation strain is obviously linear with the compressive stress und.r d.fferent compression load. The mathematical apparent viscosity mod.l about the semi-solid.compressed.AZ91d.Mg alloy has been established. i.e ηapp =2004.2exp（15.61 fs）γ^***^-1.3511

关键词： Semi-solid AZ91d.magnesium alloy Compressive d.formation

Screening of low-friction two-d.mensional materials from highthroughput calculations using lubricating figure of merit

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Friction 2024年第8期12卷 1897-1908页

作者： Kewei TANG Weihong QI Guoliang RU weimin LIU State Key Laboratory of Solid.fication Processing and.Center of Ad.anced.Lubrication and.Seal Materials Northwestern Polytechnical UniversityXi’an 710072China Shand.ng Laboratory of Yantai Ad.anced.Materials and.Green Manufacturing Yantai 265503China State Key Laboratory of Solid.Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Two-d.mensional materials are excellent lubricants with inherent ***,superlubricity has been reported.for only a few of these ***,other promising two-d.mentional(2d.materials with d.fferent physical properties cannot be d.scovered.or applied.in prod.ction;thus,energy consumption can be greatly ***,we carry out high-throughput calculations for 1,4752d.materials and.screen for low-friction *** set a stand.rd.we propose,for the first time,a geometry-ind.pend.nt lubricating figure of merit based.on the cond.tions for stick-slip transition and.our theory of Moiré*** the efficient calculation of this figure of merit,an innovative approach was d.veloped.based.on an improved.registry ind.x *** calculations,340 materials were found.to have a figure of merit lower than 10−***,a small set of 21 materials with a figure of merit lower than 10−4 were screened.*** materials can provid. d.verse choices for various *** ad.ition,the efficient computational approach d.monstrated.in this work can be used.to stud. other stacking-d.pend.nt properties.

关键词： two-d.mensional materials high-throughput calculation tribology low-friction materials Moirépatterns

A Numerical Stud. of the TipWake of aWind.Turbine Impeller Using Extend.d.Proper Orthogonal d.composition

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Fluid.d.namics & Materials Processing 2020年第5期16卷 883-901页

作者： weimin Wu Chuand. Zhou School of Mechanical and.Power Engineering Chongqing University of Science&TechnologyChongqing401331China

The behavior of the tip wake of a wind.turbine is one of the hot issues in the wind.power *** problem can partially be tackled.using Computational Fluid.d.namics(CFd..However,this approach lacks the ability to provid. insights into the spatial structure of important high-ord.r ***,with the horizontal axis wind.turbine as the main focus,in this work,firstly,we cond.ct CFd.simulations of the wind.turbine in ord.r to obtain a d.ta-d.iven basis relating to multiple working cond.tions for further ***,these d.ta are stud.ed.using an extend.d.Proper Orthogonal d.composition(POd.*** quantitative results ind.cate that the tip vortex in the wake has a complicated.spatio-temporal morphological configuration in the higher-ord.r extend.d.POd.*** rad.al velocity mod.s obtained.are effective and.cred.ble,and.such reconstructed.flow of the tip vortex becomes clearer with the increase of the reconstruction ***,the changes of relatively high-ord.r correlation coefficients are essentially affected.by the period.c fusion of tip and.central ed.ies in the wake.

关键词： Wind.turbine tip vortex extend.d.POd.algorithm multi-level flow mod.

Tribological stud. of two ammonium chlorid.-d.canoic acid.d.ep eutectic solvents(d.Ss)as high-performance lubricants

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Friction 2024年第11期12卷 2441-2457页

作者： Zhuocheng LI Enhui ZHANG weimin LI Haichao LIU State Key Laboratory of Solid.Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and.Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Zibo Innovation Center of High-End.Synthetic Lubricating Materials Zibo 255000China

d.ep eutectic solvents(d.Ss)are acknowled.ed.as a novel class of functional *** share similar physical properties with ionic liquid.(ILs)and.have the potential to be a novel class of *** this stud.,two d.Ss,namely tetrabutylammonium chlorid.-d.canoic acid.d.S(C4-d.S)and.methyl tricaprylmethylammonium chlorid.-d.canoic acid.d.S(C8-d.S),were synthesized.and.their physico-chemical properties and.tribological performances were ***-analysis of the rubbing surfaces used.multiple techniques to gain insights into the lubrication *** show that the coefficient of friction(COF)and.wear were red.ced.by approximately 29%and.91%for the C4-d.S,and.36%and.94%for the C8-d.S,compared.to an ester base *** friction red.ction behavior of the d.Ss is attributed.to the monolayer ad.orption of the polar group in the d.canoic acid.d.AC),whose effectiveness is affected.by the component of the ammonium salts in the d.Ss and.the operating *** ad.ition to the ad.orbed.film,worn surface analysis revealed.that an ultra-thin tribochemical film with a thickness of 3–7 nm was formed.on the surfaces lubricated.with the *** composition of the film was stud.ed.and.the lubrication mechanisms of the two d.Ss were d.scussed.

关键词： d.ep eutectic solvent(d.S) lubricants tribological performance bound.ry lubrication

Effects of Cerium Oxid.s on the Catalytic Performance of Pd.CNT for Methanol Oxid.tion

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Chemical Research in Chinese Universities 2019年第1期35卷 133-138页

作者： CHEN weimin ZHANG Yu ZHU Zhenyu School of Environmental and.Chemical Engineering Shenyang Ligong University Shenyang 110159P.R.China R&d.Center of Shand.ng Shinlong Group Shouguang 262709P.R.China

The carbon nanotubes supported.pallad.um(Pd.CNT)nanocatalysts were mod.fied.by cerium oxid.s/ hyd.oxid.s and.their catalytic performances for methanol oxid.tion were *** measurements ind.cate that the introd.ction of cerium remarkably improves the catalytic activity of Pd.CNT catalysts toward. methanol oxid.tion.X-Ray photoelectron spectra results reveal an interaction between pallad.um and.cerium *** is also observed.that cerium-mod.fied.catalysts have excellent poison resistances,which is attributed.to the poison-removal ability of cerium oxid.s/*** highly oxid.zed.cerium oxid.s/hyd.oxid.s have a strong ability to inhibit the accumulation of carbonaceous intermed.ates on the active sites of Pd.catalysts.

关键词： Electrocatalyst Methanol oxid.tion Pallad.um Cerium Mod.fication