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简介：Toestimatethelifetimeofpneumaticcylinderinmachinetool(orautomaticassemblyline),newreliabilitymethodologyforparametricacceleratedlifetesting(ALT)issuggested.ItconsistsofparametricALTplan,generalizedlife-stressfailuremodelwithaneweffortconcept,accelerationfactor,andsamplesizeequation.ThisnewparametricALTenablesanengineertoestimatethelifetimeofacommerciallypartsbyuncoveringthefailurethroughacceleratedtestingundersevereconditions.Asacasestudy,twocommercialproductsofthepneumaticcylinderinmachinetoolweretested.ForcompanyA,wefoundthehardeningandwearofpistonseallikethatoffieldatnormalconditions.Asincreasingthepressure,thepneumaticcylindersweretested.Basedontheacceleratedconditions—0.8MPaand1.2MPaat23℃,B1lifeat0.63MPaand23℃wasextrapolatedas2.39×10^6.Ontheotherhand,forcompanyB,wefoundtherodcapblockedbyslurrylikethoseoffieldsamples.Basedontheacceleratedconditions—0.8MPaand1.4MPaat23℃,B1lifeat0.63MPaand23℃wasextrapolatedas2.51×10^6.Comparingthemwithtestingdataatnormaluseconditions,weknewthattheestimationerrorforbothcompanieswaslessthan10%.

简介：AtheoreticalanalysisontheelectricdoublelayerformednearthesurfaceofaninfinitecylinderwithanellipticalcrosssectionandaprescribedelectricpotentialinanionicconductorwasperformedusingthelinearizedGouy–Chapmantheory.Asemi-analyticalsolutionintermsoftheMathieufunctionswasobtained.Thedistributionsoftheelectricpotential,cations,anions,andelectricfieldwerecalculated.Theeffectsofvariousphysicalandgeometricparameterswereexamined.Thefieldsvaryrapidlyneartheellipticalboundaryandarenearlyuniformatfarfield.Electricfieldconcentrationswerefoundattheendsofthesemi-majorandsemi-minoraxesoftheellipse.Theseconcentrationsaresensitivetothephysicalandgeometricparameters.

简介：由于胭脂波浪的物理机制的复杂性，rogue-wavestructure相互作用问题的理论学习仍然取得很少进步。为常规形状的结构，然而，给理论分析是可能的，如果流氓波浪的一个相对简单的模型被使用。波浪负担，由作为胭脂波浪的一个直觉的基本模型被知道的一个集中的波浪导致了，在沉没半的柱体之上被学习经分解。集中的波浪由高斯信封波浪是近似的，包含流氓波浪的大多数特征的一个理想的模型。衍射速度潜力通过水平力量的流动地，和公式的分离被导出，弯曲时刻被建议。导出的公式适当地被简化，并且对数字结果通过比较验证了。另外，参数的影响集中的沉没深度和波浪例如集中的度，放，彻底地被调查。

简介：Thehydrodynamicanalysisofmulti-floatingbodiesisimportantandwidelyusedinmarineengineering.Inthisstudy,wesystematicallysimulatedthewavediffractionproblemofafixedverticalfour-cylinderstructureinregularwavesinthetimedomaininaviscousnumericalwavetank.Thehydrodynamicinteractionofwaveswithabottom-mountedstructureconsistingoffourverticalcylindersarrangedatthecornersofasquareshowsacomplicatedinterferencephenomenon.Inthispaper,weillustrateandanalyzetherun-uparoundthestructureandthecorrespondingwaveforces.Toinvestigatetheviscouseffectonthenear-trappingphenomenon,wepayparticularattentiontoinvestigatingthewavesnear-trappedinsidethefour-cylinderstructure,andmakeacomparativestudyoftheviscous-andinviscid-flowsolutionswiththeexperimentalmeasurements.Theresultsshowthatthemaximumwaveelevationoccursontheinnersideoftheleesidecylinder,andthatthewaveelevationsontheoutersideofthecylindersarelowerthanthoseontheinnerside.Wecanconcludethatviscosityhasanobviousdampingeffectonwaveelevationsinsidethestructure.Thecylindersshowatendencytodriftapartfromeachotherwhenthenear-trappingphenomenonoccurs.

简介：ItiswellknownthattheReynoldsnumberhasasignificanteffectonthevortex-inducedvibrations(VIV)ofcylinders.Inthispaper,anovelin-line(IL)andcross-flow(CF)couplingVIVpredictionmodelforcircularcylindershasbeenproposed,inwhichtheinfluenceoftheReynoldsnumberwascomprehensivelyconsidered.TheStrouhalnumberlinkedwiththevortexsheddingfrequencywascalculatedthroughafunctionoftheReynoldsnumber.ThecoefficientofthemeandragforcewasfittedasanewpiecewisefunctionoftheReynoldsnumber,anditsamplificationresultedfromtheCFVIVwasalsotakenintoaccount.TheoscillatingdragandliftforcesweremodelledwithclassicalvanderPolwakeoscillatorsandtheirempiricalparametersweredeterminedbasedonthelock-inboundariesandthepeak-amplitudeformulas.Anewpeak-amplitudeformulafortheILVIVwasdevelopedundertheresonanceconditionwithrespecttothemass-dampingratioandtheReynoldsnumber.Whencomparedwiththeresultsfromtheexperimentsandsomeotherpredictionmodels,thepresentmodelcouldgivegoodestimationsonthevibrationamplitudesandfrequenciesoftheVIVbothforelastically-mountedrigidandlongflexiblecylinders.ThepresentmodelconsideringtheinfluenceoftheReynoldsnumbercouldgenerallyprovidebetterresultsthanthatneglectingtheeffectoftheReynoldsnumber.

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