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简介：WithoutsimplifyingtheN-SequationsofGermano’s,westudytheflowinahelicalcircularpipeemployingperturbationmethod.Athirdperturbationsolutionisfullypresented.Thefirst-second-andthird-ordereffectsofcurvatureкandtorsionтonthesecondaryflowandaxialvelocityarediscussedindetail.Thefirst-ordereffectofcurvatureistoformtwocounter-rotatingcellsofthesecondaryflowandtopushthemaximurnaxialvelocitytotheouterbend.Thetwocellsarepushedtotheouterbendbythepuresecond-ordereffectofcurvature.Thecombinedhigher-order(second-,third-)effectsofcurvatureandtorsion,arefoundtobeanenlargementofthelowervortexofthesecondaryflowatexpenseoftheupperoneandaclockwiseshiftofthecentersofthesecondaryvorticesandthelocationofmaximumaxialvelocity.Whentheaxialpressuregradientissmallenoughorthetorsionissufficientlylargerthanthecurvature,thelocationofthemaximalaxialvelocityisneartheinnerbend.Theequationofthevolumefluxisobtainedfromintegratingtheperturbationsolutionsofaxialvelocity.Fromtheequationthevalidityrangeoftheperturbationsolutionsinthispapercanbeobtainedandtheconclusionthatthethreetermsoftorsionhavenoeffectonthevolumefluxcaneasilybedrawn.Whentheaxialpressuregradientislessthan22.67,thevolumefluxinahelicalpipeislargerthanthatinastraightpipe.

简介：Inthispaper,aphotoelectricdeviceisintroduced,whichisusedinde-tectingthequalityoninternalsurfaceofthinandlongsteelpipe.Inthisdevice,theCCTVlensisusedforextracttheflawinformationoninternalsurfaceofthepipe,andmakeIBM-PC/AT486computerascontrollingandimageprocessingsystem.Bythisinstrument,thefunctions,suchasthedigitalconversiongofinputinformation,imageprocessing,classificationofrecognitionandoutputdisplaycanbeobtained,Inthepetroleumandchemicalindustry,byusingthisapparatus,wecandetectthequalithoninternalsurfaceofvariousmetalpipeswithreal-timeautomatically.

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简介：AnewcentrifugebasedmethodfordeterminingtheresponseofcontinuousburiedpipetoPGDispresented.ThephysicalcharacteristicsoftheRPI's100g-tongeotechnicalcentrifugeandthecurrentlifelineexperimentsplit-boxaredescribed:Thesplit-boxcontainsthemodelpipelineandsurroundingsoilandismanufacturedsuchthathalfcanbeoffset,inflight,simulatingPGD.Inaddition,governingsimilituderelationswhichallowonetodeterminethephysicalcharacteristics,(diameter,wallthicknessandmaterialmodulusofelasticity)ofthemodelpipelinearepresented.Finally,recordedstrainsinducedintwoburiedpipeswithprototypediametersof0.63mand0.95m(24and36inch)subjectto0.6and2.0meters(2and6feet)offullscalefaultoffsetsandpresentedandcomparedtocorrespondingFEresults.

简介：Tosolvetheproblemoflowefficiencyinpiperoutingdesign,animprovedgeneticalgorithmbasedapproachisproposed.Topresentthisapproach,thepapermainlydescribesagenerationmethodofnodesconsideringthesafetydistanceofpipesandthedirectionalconstraintsatterminals,thedefinitionofadoublecodingtechnique,thecollisiondetectionmethod,theconceptofenergyandthedefinitionoffitnessfunctions.Thesimilaritydetectionisintroducedtopreventclosebreedinginthecrossoveroperator,theselectionpressureiscontrolledaccordingtotheevolutionsituationandaheuristicmutationmethodisusedtoboosttheevolution.Simulationcaseshowsthatthisapproachismorepracticalandcansatisfydifferentdesignrequirementsbychangingalgorithmparameters.

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简介：Theinterfacialbehaviorofpipejointsisstudiedinthispaper.Firstly,throughnonlinearfracturemechanics,theanalyticalexpressionsofinterfacialshearstressandtheloaddisplacementrelationshipatloadedendofpipejointsundertorsionloadsareobtained.Thustheshearstresspropagationandthedebondingprocessofthewholeinterfacefordifferentbondlengthscanbepredicted.Secondly,throughtheanalyticalsolutions,theinfluencesofdifferentbondlengthsontheload-displacementcurveandtheultimateloadarestudied.Thestresstransfermechanism,theinterfacecrackpropagationandtheductilitybehaviorofthejointscanbeexplained.

简介：Thesteelreinforcedplasticpipeisakindofgreenenvironmentalprotectionpipelineswithdouble-sidescorrosionresistingandbetterwithstandingtomediumworkingpressure.Thestructureandtechnicalprocessofthispipearedescribedbrieflyinthispaper,andthefiniteelementanalysishasbeendoneforthesakeofunderstandingthedistributionsofstressanddisplacementinsidethispipeunderhydrostaticpressure.Theanalysisresultsareveryimportantforsafetyapplicationofthesteelreinforcedplasticpipe.

简介：Basedontheformerresearchworkoftheauthors,theresistanceofdifferentsolidparticlesuspensionflowinaverticalpipeisanalysed,andinvestigatedexperimentally.Theapplicableformulasofpressuredroparepresented.Twotypesofpar-ticles,talcumpowderandglassbeads,areconvcyedinthetestwhichhasbeencarriedoutatvariousairvclocitiesof10to28m/sandattheratioofsolids-airmassflowraterangedfrom0to2.Theexperimentalresultsshowagoodagreementwiththecalculatedones.

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简介：Inthispaper,weconsideraninverseproblemofdeterminingthecorrosionoccurringinaninaccessibleinteriorpartofapipefromthemeasurementsontheouterboundary.TheproblemismodelledbyLaplace'sequationwithanunknowntermγintheboundaryconditionontheinnerboundary.BasedontheMaz'yaiterativealgorithm,aregularizedBEMmethodisproposedforobtainingapproximatesolutionsforthisinverseproblem.Thenumericalresultsshowthatourmethodcanbeeasilyrealizedandisquiteeffective.

简介：当流动正在波动时，实验被进行学习流动的特征。试验性的结果显示出流动率和压力落下变化之间的阶段差别。波动的流动率和压力落下之间的这阶段差别为laminar流动被分析。分析证明阶段差别随着流动变化，管子半径，密度和液体的动态粘性的时期变化。波动的管子流动然后数字地被模仿。数字模拟的结果与理论价值和试验性的结果相比。当流动率作为一个正弦波浪与时间波动时，压力落下与一样的频率波动，这被显示出，并且他们之间有阶段差别。

简介：Inthispaper,weproposeandexperimentallydemonstrateamethodtorealizeapolarizationdetectorbyusingacommerciallyavailablepolymethylmethacrylate(PMMA)pipe.Anasymmetricpolarization-relatedstructureisfabricatedbyetchingdifferentgratingstructuresontheexternalsurfaceofthepipe.Theresultsshowthatwhenthepiperotatesupto90°,thepeakofthetransmissionspectrumcanevidentlyshifttowardsthelowfrequency,whichmeansthepipewithgratingstructurescanserveasapolarizationdetector.Thisdesignpossessesthemeritsofasimplestructureandeasyfabrication.

简介：Thispaperconsidersthestationaryflowofincompressiblemicropolarfluidthroughathincylindricalpipegovernedbythepressuredropbetweenpipe'sends.Itsgoalistoinvestigatetheinfluenceoftheviscositycoefficientsontheeffectiveflow.Dependingonthemagnitudeofviscositycoefficientswithrespecttothepipe'sthickness,itderivesdifferentasymptoticmodelsanddiscussestheirproperties.

简介：NonlinearMHDKelvin-Helmholtz（K-H）instabilityinapipeistreatedwiththederiva-tiveexpansionmethodinthepresentpaperThelinearstabilityproblemwasdiscussedinthepastbyChandrasekhar（1961）andXuetal.（1981）.Nagano（1979）discussedthenonlinearMHDK-Hinstabilitywithinfinitedepth.Heusedthesingularperturbationmethodandextrapolatedtheob-tainedsecondordermodifierofamplitudevs.frequencytoseekthenonlineareffectontheinstabilitygrowthrateγ.However,inourview,suchanextrapolationisinappropriate.Becausewhentheinstabili-tysetsin,thegrowthratesofhigher,ordertermsontherighthandsideofequationswillexceedthecor-respondingsecularproducingterms,sotheexpansionwillstillbecomemeaninglessevenifthesecularproducingtermsareeliminated.Mathematicallyspeaking,it’simpossibletoderiveformula（39）whenγ02isnegativeinNagano’spaper.Moreover,evenasearlyasγ02→O+,theexpansionbe-comesinvalidbecausethe2ndordermodifierγ2（inhisformula（56））tendstoinfinity.Thisweak-nessisremovedinthispaper,andtheresultisextendedtothecaseofapipewithfinitedepth.

简介：基于液体动力学，热转移和声学的结果，一个计算液体动力学(CFD)方法被利用在一根Rijke管子内学习声学的特征和自我刺激的跳动机制。为了避免解决有限振幅的站的荒谬的边界条件，在Rijkethermo声学的系统飘动，在流动领域里当模特儿的模拟，它联合了有它的外层空间的管子内部，被执行代替传统的方法处于良好的竟技状态内部流动地数字调查。为在包括在热来源，摆动压力和摆动速度附近的空气的不稳定的热上的关系的精力方程的热来源的一个假设被介绍。为了反映Rijke的本质，尖叫，自我刺激的摆动上的模拟借助于它压力，速度和温度的自己的跳动被进行。这个方法能使集中过程稳定并且有效地避免分叉。自我刺激的Rijke管子的物理现象被分析。而且，Rijke管子的自我刺激的摆动上的机制是这个方法上的explained.Based，关于有不同尺寸和嘴的不同形状的Rijke管子的声学的特征的比较研究被执行。模拟结果令人满意地同意了试验性的数据。结果证明这数字模拟能被用来为Rijke管子的设计申请学习嘴的健全压力。

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简介：Hydrodynamicandthermalcharacteristicsinapipewithsinusoidalwavysurfaceforsteadylaminarflowareinvestigatednumericallyinthepresentstudy.TheintegralformsofgoverningequationsarediscretizedusingcontrolvolumebasedFinitevolumemethodwithcollocatedvariablearrangement.SIMPLEalgorithmisusedandTDMAsolverisappliedforsolutionofsystemofequations.Apipeoflengthequalto4λisconsidered.Effectofsurfacewaviness,determinedbywavelength-amplituderatioλ/a(=L^*),onflowandthermalfieldispresented.ThesimulationworkhasbeencarriedoutforL^*=11.0-30.0foraReynoldsnumberrange50to2000.Resultsarepresentedintheformofstreamfunction,isothermallines,velocityandvorticityprofiles,changeofmeanfrictionfactor,variationinskinfriction,localandaverageNusseltnumberwithReynoldsnumber,wavenumber(n)andL^*.Foraparticulargeometry,lengthofcirculationzoneincreaseswithreynoldsnumberandapproachesalimitingvalueforhigherReynoldsnumber.Wallshearstressinthebulgepartofthechannelshowssmallervaluesthataffectlargely.therateofheattransferandNusseltnumbershowsminimumvaluesinthisregion.Thiscirculationzonedrasticallyincreaseswiththeincreaseofsurfacewavinessshowinghighmeanfrictionfactorperwavelength.MeanfrictionfactorinverselyvarieswithReynoldsnumber.Acorrelationisproposedforcalculatingfrictionfactorintheformf=C/(Re)^m,where‘C’and‘m’representstwopolynomialsofdegree4and2respectivelyandarefunctionofL^*.Higherwavinessofthesurfaceshowsthehigherheattransferratethanlowerwaviness.Heattransferratefallsalmostexponentiallyalongtheaxialdirectionwiththeincreaseofwavenumber.

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