简介：Lowweightandcompactnessarethemainrequirementsoncomponentsforexoskeletons.Fordrivesthismeansalsohighefficiencytokeepenergystorageandpowertransducingdevicessmall.Thedigitalhydrauliccylinderdriveisanexcellentcandidatetobecomeasuperiortechnologyforexoskeletonactuation.Itrequiresseveralvalvestocontrolpressureinitsmanychambers.Solenoidvalvessufferfromthehighweightandspaceofthesolenoids.Inthispaper,thehydraulicbinarycounterinaconfigurationwithonlypassiveelementsisstudiedmathematically,sinceitcancontroladigitalcylinderwithmuchsmallerspaceandweightthanmagneticallyactuatedvalves.Fromqualitativeconsiderationsofthesystemequationssupplementedbyanumericalstudy,itisshownthatsuchacounterworksproperly.Butitposesrequirementsonthecontrolpressurerangewhicharedifficulttofulfilfordigitalcylinderdriveswithmorethanfivechambers.

简介：Thefeaturesofunsteadyflowsuchaspressurevariationandfluctuationinalargehydraulicturbineusuallyleadtotheinstabilityofoperation.Thisarticlereportstherecentinsiteinvestigationconcerningthecharacteristicfrequenciesinpressurefluctuation,shafttorsionaloscillationandstructuralvibrationofaprototype700MWFrancisturbineunit.Theinvestigationwascarriedoutforawideloadrangeof200MW-700MWintheconditionofwaterhead57m-90m.Anextensiveanalysisofbothtime-historyandfrequencydataoftheseunsteadyhydraulicbehaviourswasconducted.Itwasobservedthatthepressurefluctuationinadrafttubeisstrongerthanthatinupstreamflowpassage.Thelowfrequencywithaboutonethirdofrotationfrequencyisdominativeforthepressurefluctuationinpartloadrange.Alsotheunsteadyfeaturesofvibrationofheadcoverandtorsionaloscillationofshaftexhibitedthesimilarfeatures.Numericalanalysisshowedthatthevibrationandoscillationarecausedbyvortexropeinthedrafttube.Inaddition,astrongvibrationwithspecialcharacteristicfrequencywasobservedfortheheadcoverinmiddleloadrange.Thepressurefluctuationinthedrafttubewiththesamefrequencywasalsorecorded.Becausethisspecialvibrationhasappearedinthedesignednormalrunningcondition,itshouldbeavoidedbycarefullyallocatingpowerloadinthefutureoperation.

简介：Thispapermainlysummarizestherecentprogressesforthecavitationstudyinthehydraulicmachineryincludingturbopumps,hydroturbines,etc..Especially,thenewlydevelopednumericalmethodsforsimulatingcavitatingturbulentflowsandtheachievementswithregardtothecomplicatedflowfeaturesrevealedbyusingadvancedopticaltechniquesaswellascavitationsimulationareintroducedsoastomakeabetterunderstandingofthecavitatingflowmechanismforhydraulicmachinery.Sincecavitationinstabilitiesarealsovitalissueandratherharmfulfortheoperationsafetyofhydromachines,wepresentthe1-Danalysismethod,whichisidentifiedtobeveryusefulforengineeringapplicationsregardingthecavitatingflowsininducers,turbinedrafttubes,etc.Thoughbothcavitationandhydraulicmachineryareextensivelydiscussedinliteratures,oneshouldbeawarethatafewproblemsstillremainsandareopenforsolution,suchasthecomprehensiveunderstandingofcavitatingturbulentflowsespeciallyinsidehydroturbines,theunneglectablediscrepanciesbetweenthenumericalandexperimentaldata,etc..Tofurtherpromotethestudyofcavitationinhydraulicmachinery,someadvancedtopicssuchasaDensity-Basedsolversuitableforhighlycompressiblecavitatingturbulentflows,avirtualcavitationtunnel,etc.areaddressedforthefutureworks.

简介：Remainingusefullife(RUL)estimationisatopicthathasgainedmoreandmoreattentioninthefieldoffluidpowersystems,thankstothetremendouspotentialsshownforimprovingsafetyandreducedproductionlosses.However,manychallengesrelatedtoRULestimationarenotsolvedyet,mainlyconnectedtothedefinitionofthehealthstatusofeachcomponent.Aprognosticmethodbasedonadata-drivenmethodologyforhydraulicsystemsishereproposedtoestimatethepercentageoflifealreadyspentbythemonitoredcomponents.Thepotentialsofthemethodologyareshownconsideringthecaseofatruck-mountedhydrauliccrane,forwhichasimulationmodelwasavailable.

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简介：Theformulaeusedtocalculatethefrictioninthenon-uniformflowchutewereexaminedwiththeexperimentaldata,andtheresultsshowthattheaccuracyoftheformulaisenoughforengineeringapplications.Acomparisonbetweentheresultsoffrictionrespectivelyfromtheuniformflowassumptionandthenon-uniformflowapproximationindicatesthattheformerisanorderofmagnitudelargerthanthelatterinthecaseofsteepchute.Thehydraulicdragonasteepchutewithaeratorswasmeasuredonthehydraulicmodeldirectlyandthecoefficientoftheaeratoreffectonthedragwasobtained.Thevariationpatternsofthewallshearjustdownstreamoftheaeratorswereinvestigatedandthemechanismoftheincreaseinthedragbyaeratorwereanalyzedqualitativelywiththemeasuredwater-depthsjustdownstreamtheaerators.

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简介：AmovablebedphysicalmodelwasconstructedtoinvestigatehydraulicdesiltationbyflushingandlateralerosionintheTapureservoir,Taiwan.Themodelscalingisbasedontherequirementfordynamicsimilarityofcohesivesedimentdepositinitiationinflushingprocesses.Formodelscaling,flumeexperimentsinvestigatingtheinitiationofcohesivesedimentdepositswerecarriedouttoestablishtherelationshipbetweencriticalshearstressoftheflowanddrydensityofthedeposit.Experimentsinthephysicalmodelwerethenperformedtomeasurethevariationsofthereservoirwaterlevel,theoutletdischargeandtheoutflowsedimentdischarge.Theprocessesofemptyingandflushingwereobservedandanalyzedinthemainflushingchannel.Oneoftheexperimentswasconductedtosimulatetheon-siteflushingoperationsonJune11,1997.Theresultsshowedthatthetotalcumulativeflushedsedimentvolumebyphysicalmodelingwasclosetothatbynumericalsimulation.Todealwiththefloodplaindeposits,experimentsoflateralerosionasanauxiliarymethodwerealsoconductedinthephysicalmodeltoinvestigatetheeffectivenessandapplicabilityfortheTapureservoir.

简介：FourgianthydraulicturbinesofYantanHydropowerSta-tionlocatedontheHongshuiRiver,GuangxiProvincearenowunderconstructionbytheHarbinElectricMachineryWorks(HEMW)ofChinaHarbinPower-PlantEquipmentCorporation(GROUP).TheturbinewillbecomethelargestindimensionforFrancistypeturbineevermadeinChina.Theexternaldiameteroftherunneris8.6m,whichissupposedtoberankedNo.3amongthelargestrunnersofthiscategoryintheworld.Eachturbineisrated

简介：Intherillerosionprocess,run-onwaterandsedimentfromupslopeareas,andrillflowhydraulicparametershavesignificanteffectsonsedimentdetachmentandtransport.However,thereisalackofdatatoquantifytheeffectsofrun-onwaterandsedimentandrillflowhydraulicparametersonrillerosionprocessatsteephillslopes,especiallyintheLoessPlateauofChina.Adual-boxsystem,consistingofa2-m-longfeederboxanda5-m-longtestboxwith26.8%slopegradientwasusedtoquantifytheeffectsofupsloperunoffandsediment,andofrillflowhydraulicparametersontherillerosionprocess.Theresultsshowedthatdetachment-transportwasdominatedinrillerosionprocesses;upsloperunoffalwayscausedthenetrilldetachmentatthedownsloperillflowchannel,andthenetrilldetachmentcausedbyupsloperunoffincreasedwithadecreaseofrunoffsedimentconcentrationfromthefeederboxoranincreaseofrainfallintensity.Upsloperunoffdischargingintotherillflowchanneloranincreaseofrainfallintensitycausedtherillflowtoshiftfromastratumflowintoaturbulentflow.Upsloperunoffhadanimportanteffectonrillflowhydraulicparameters,suchasrillflowvelocity,hydraulicradius,Reynoldsnumber,FroudenumberandtheDarcy-Weisbachresistancecoefficient.Thenetrilldetachmentcausedbyupsloperunoffincreasedastherelativeincrementsofrillflowvelocity,ReynoldsnumberandFroudenumbercausedbyupsloperunoffincreased.Incontrast,thenetrilldetachmentdecreasedwithanincreaseoftherelativedecrementoftheDarcy-Weisbachresistancecoefficientcausedbyupsloperunoff.Thesefindingswillhelptoimprovetheunderstandingoftheeffectsofrun-onwaterandsedimentontheerosionprocessandtofindcontrolstrategiestominimizetheimpactofrun-onwater.

简介：Hydraulicspinalcordandcaudaequinanerveinjuriesareveryuncommon.Since1996,wehavereceivedandtreated4patientswithhydraulicspinalcordandcaudaequinainjuries.Thisreportgivesadetaildescription.Fourpatientswithhydraulicspinalcordandcaudaequinanerveinjuries,male:3,female:1,aging13-56yearshavebeentreatedinourhospitalsince1996.Extraduralblockinginjurywasin1patient,extraduralanaesthesiainjuryin1patientandintraspinalcanalmyelographyinjuryin2patients;thesegmentsofintraspinalcanalwereL2-3andL3-4.Onepatientwasaccompaniedbyfemoralfracture,2patientsbyintraspinaltumorand1patienthadoperationbecauseofprolapseoflumbarintervertebraldisc.

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简介：ThecurvedsurfaceofballmovementisaconnectingDentpipecommonlyusedinhydraulicengineering.Thecurvedsurfaceposesacomplicatedproblemwithcomputation.Themathematicmodelofthecircularcurvedsurfaceofballmovementinengineeringissetupbyadoptingtheconceptofenvelopecurvedsurface.

简介：Submergedvegetationhasasignificantimpactonwaterflowvelocity.Currentinvestigationsincludetheimpactthroughaddingdragresistanceandincreasingbottomroughnesscoefficient,whichcannotelucidatethecharactersofrealsubmergedvegetation.Toevaluatetheeffectsofsubmergedvegetationonwatercurrentsatdifferentvelocities,alaboratoryexperimentwasconductedusingthreekindsofvegetations.Theeffectiveheightsofthesevegetationsonvaryingflowvelocitieswereevaluated.AnequationdescribingtherelationshipbetweenthenormalizedresistanceofthesubmergedplantsandtheReynoldsnumberbasedontheplanteffectiveheightwasthenestablishedandusedtocalculatethehydraulicresistanceparametersofsubmergedplantsindifferentstagesofgrowth.

简介：Elbowdraft-tubesarewidelyusedinlargeandmedium-sizedhydropowerstationsinmanycountries.Duringtheapplication,handlingthesomatotypeofelbowtubeshasbeenfoundchallenging:inordertomaintainthedesignedshapeofdrafttubeandtomeettherequirementofconstructionlofting,theconfigurationofreinforcingbarsandthefabricationoftemplates,thegeometryofelbowtubeshastobeaccuratelycalculatedtodrawengineeringgraphics.Basedonthederivedequationsinthispaper,themotionofelbowtubecurveenvelopeissimulatedbyusingcomputers,whichshowsdirectlythesmoothnessofthecurveandprovidesdynamicsimulationforthestudyandoptimizationofthedesignandconstructionofelbowdrafttubes,alongwiththefrontviewandbottomview.

简介：ThispaperdescribestheNiiMiprocessdesignedtotreatlandscapewater.ThemainaimoftheresearchwastoinvestigatethefeasibilityofNiiMiforremovingorganicandnutrimentmaterialsfromlandscapewater.Duringthebatch-scaleNiiMioperation,theremovalratesofcolorrangedfrom66.7%-80%,ofturbidityfrom31.7%-89.3%,ofchemicaloxygendemand(COD)from7%-36.5%,oftotalphosphor(TP)from43%-84.2%,ofsolublephosphatefrom42.9%-100%,oftotalnitrogen(TN)from4.2%-46.7%,andofNH4+-Nfrom39.3%-100%atthehydraulicloadingof0.2m3/(m2·d).ResultsshowedthattheremovalefficienciesofCOD,TP,solublephosphateandTNdecreasedwiththedeclineinthetemperature.TheNiiMiprocesshadastrongshockloadingabilityfortheremovaloftheorganics,turbidity,TP,solublephosphate,TNandNH4+-N.Threesodiumchloridetracerstudieswereconducted,labeledasTS1,TS2,andTS3,respectively.Themeanhydraulicretentiontimes(meanHRTs)were31hand28hforTS1andTS2,respectively,indicatingtheoccurrenceofadeadzonevolumeof12%and20%forTS1andTS2,respectively.TS1andTS2displayedtheoccurrenceofshort-circuitingintheNiiMisystem.ThecomparisonresultsbetweenTS1andTS2werefurtherconfirmedinthevaluesobtainedforsomeindicators,suchasvolumetricefficiency(e),short-circuiting(S),hydraulicefficiency(λ)andnumberofcontinuouslystirredtankreactors(N).

简介：土壤的描述水力的性质对环境管理重要；然而，直接测量土壤勤劳、费时间、昂贵，这很好被认出水力的性质。这份报纸考察作为一个其他的工具过去常估计土壤的pedotransfer功能(PTF)的发展水力的性质在最后二十年期间。象察觉到的卫星imagery/remote一样的现代土壤调查技术在开发PTF被使用了。比作机械学的途径，在物理性质之间的实验关系和水力的性质为预言土壤收到了宽偏爱水力的性质。许多PTF能在文学基于不同参量的功能被发现。很多个研究人员追求了能描述土壤的所有类型的水保留特征的通用功能，但是没有单个功能能被称为通用尽管货车Genuchten(VG)功能是广泛地采用的大多数。大多数报导参量的PTF集中于获得水保留的参数弄弯的VG(WRC)的评价。很多个物理、词法、化学的性质在PTF被用作预言者变量。通常，回归算法/技术(统计/神经的回归)被用于校准PTF。然而，有利用数据采矿技术的报告，例如，模式识别和基因算法。精制过去常让刻度改进PTF的精确性和可靠性的数据是批评的，这被推断。包括根均方差(RMSE)，许多统计索引同意索引(d)，最大的绝对错误(我)，吝啬的绝对错误(MAE)，决心的系数(r2)和关联系数(r)，被不同研究人员使用了评估并且验证PTF。这被说服是地点特定，对PTF的研究兴趣将继续直到通用PTF被开发并且验证。在未来研究，改进了方法将被要求从存在数据库提取信息。

简介：Thehydrauliccharacteristicsattheconfluencereachofriverandlakeareinfluencedbymultiplefactorssuchasinflow,topographyandvegetationresistance,andareverycomplicated.Inthisarticle,theconfluencereachofYangtzeRiverandDong-tingLakeisselectedasaspecialexampleandahybridmodelisbuilttostudytheflowatthisconfluence,withtheconsiderationoftheinteractionsbetweenaquaticvegetationandflow.Validationtestsandcalculationsshowthatthemodeliseffectiveandhighlyaccurate.Thesimulationsshowthattheseparationleveeattheconfluencereachmaychangethedischargecapacityinthefloodplain,whichwouldbeenhancedintheupperreachofthelevee,hardlychangedinthemiddlereachandreducedatthelowerplace.Moreover,theseparationleveealsolimitsthewaterexchangebetweentheYangtzeRiverandDong-tingLake.

简介：Quartercircularbreakwater(QCB)isanew-typebreakwaterdevelopedfromsemi-circularbreakwater(SCB).ThesuperstructureofQCBiscomposedofaquartercircularfrontwall,ahorizontalbaseslabandaverticalrearwall.ThewidthofQCB'sbaseslabisabouthalfthatofSCB,whichmakesQCBsuitabletobeusedonrelativelyfirmsoilfoundation.ThenumericalwaveflumebasedontheReynoldsaveragedNavier-StokesequationsforimpressibleviscosityfluidisadoptedinthispapertosimulatethehydraulicperformancesofQCB.SincethegeometryofbothbreakwatersissimilarandSCBhasbeenstudiedindepth,thehydraulicperformancesofQCBaregivenincomparisonwiththoseofSCB.

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