简介:在强风和影响负担下面造结构的进步倒塌在整个世界吸引了大注意。进步倒塌分析为对进步倒塌造结构爆炸并且影响负担的一个经济、安全的图案是必要的。因为进步倒塌的灾难的性质和构造或翻新大楼抵抗它的潜在地高的费用,进步倒塌分析方法是可靠的,是必要的。为工程师,他们执行进步倒塌评估的方法论不必仅仅精确、简明,而且容易快被使用并且工作。因此,许多研究人员一直在花大量在最近开发可靠、有效、直接的进步倒塌分析方法的努力。在现在的纸,在文学可得到的当前的进步倒塌分析方法被考察。他们的适用性,适用性和可靠性被讨论。我们为在强风负担下面的增强的具体框架的进步倒塌分析的最近的建议新方法也被介绍。
简介:在易碎的材料的动态裂缝繁殖的预言仍然是许多设计的域里的一个重要问题。重新协调的技术基于放大边界,有限元素方法(SBFEM)被扩大在易碎的材料预言动态裂缝繁殖。结构第一被划分成很多superelements,仅仅的边界是有线元素的discretized的需要。在SBFEM明确的表达,僵硬和超级元素的罐头的集体矩阵与标准有限元素无缝地被联合,因此,通用性的优点和FEM的灵活性很好被维持。结构的短暂反应能用一个标准时间集成计划在时间领域直接被计算。当时,动态压力紧张因素(DSIF)能由于SBFEM的半分析的性质在裂缝繁殖期间是解决的经分解。为裂缝尖端的仅仅好网孔discretization超级元素被需要为压力紧张因素(SIF)的决心保证要求的精确性。根据预言的裂缝尖端位置,有最小的网孔变化的一个简单重新协调的算法被建议模仿动态裂缝繁殖。数字例子显示建议方法能有效地被用来包括一个中央裂缝在一个有限大小的矩形的盘子中处理动态裂缝繁殖。比较与在文学可得到的结果被做,它显示出在对方之间的好同意。
简介:SomelaboratorydiffusiontestswereconductedwithdiffusiondevicetodeterminethediffusioncoefficientofCr(Ⅵ)ionpassingthroughDalianredclaysamples.TheconcentrationsofCr(Ⅵ)atdifferentplacesofthesampleswerethenmeasuredspectrophotometricallyafterastandingtimeof1000d.Aone-dimensionalsolutetransportequationwasusedtosimulatethetransportofCr(Ⅵ)throughclaysamples.Back-calculationofdiffusioncoefficientofCr(Ⅵ)wasmadewithfinitedifferencemethod.Parametricanalysiswasconductedtosimulatevariationsinsoildrydensity,temperature,pHandstandingtime.Theresultsshowthatthemethodusedinthispaperissimpleandeffective.ThediffusioncoefficientofCr(Ⅵ)inDalianredclayvariesfrom1.50×10-7cm2/sto2.08×10-7cm2/s.After1000ddiffusion,theconcentrationofthesourcesolutiondropsdownto1.27mg/Lfrom62.5mg/L,andthediffusiondistanceisonly3.5cm.Undertheassumptionthatdiffusioncoefficientisconstant,thediffusioneffectbecomesmoreobviouswithlowerdensity,lowertemperature,higherpHvalue,andmuchmoretime.
简介:In-situvanesheartestisfrequentlyperformedtodetermineshearstrengthforslopestabilityanalysisinTianjinNewHarbor.However,thesoilshearstrengthvarieswiththeshearplaneorientation.Apossiblemeanstoreducetheeffectofdirectionaldependencyofshearstrengthistoconvertthein-situvaneshearstrengthintoundrainedshearstrengthparameters.Amethodofconvertingin-situvaneshearstrengthintoundrainedshearstrengthparametersispresented.Theshearstrengthparametersdeterminedforallofthein-situvaneshearstrengthsaresubjectedtostatisticalregressionanalysistotakeintoconsiderationthepossibleeffectofnon-homogeneityinthesoftclaydeposit.Usingtheregressedshearstrengthparameters,slopestabilityanalysesareperformedforfiveexistingsoilslopes.Theresultsofstabilityanalysesindicatethatthesafetyfactorsobtainedfromtheconvertedparametersreflectthestateoftheslopesanalyzedmuchbetterthanthoseobtainedfromin-situvaneshearstrengthandlaboratoryconsolidated-undrainedandunconsolidated-undrainedstrengthparameters.Itisconcludedthatthepresentedmethsodofdeterminingundrainedshearstrengthparametersforin-situvaneshearstrengthiseffective.
简介:Toeffectivelyreducethedamagetopeopleanddevicesincivildefenseengineeringsubjectedtoblastshock,ablastshockisolationsystemwithmagnetorheologicalfluiddampers(MRFD)isproposed.MRFDcanprovidecontinuouslyadjustableCoulombfrictionandhasmanyadvantagesforsemi-activecontrol.NumericalsimulationofthisisolationsystemisfinishedusingMatlabsimulinktoolbox.Generalsemi-activecontrolalgorithmsareconsidedbasedoninstantaneousoptimalactivecontrolalgorithm.Andtheresultsindicatethattheshockisolationsystemcanworkefficiently,decreasingabout93%ofthepeakaccelerationoftheisolationfloor.
简介:Consideringtheeffectsofparticlecrushingandintermediateprincipalstressonmaterialyieldingstrength,thespatialmobilizationplane(SMP)yieldingcriterionandstateparametermodelincludingageneralcriticalstatelineareselectedintheanalysisofcylindricalcavityexpansion.Meanwhile,combiningRowe'sflowruleandBolton'ssimplificationtostress-dilatancyrelationshiptoreflectsoilsheardilatancyandsofteningbehavior,thispaperanalyzestheproblemofcylindricalcavityexpansioni...
简介:Toanalyzethefactorsaffectingtheleakagerateofwaterdistributionsystem,webuiltamacroscopic“leakagerate–leakagefactors”(LRLF)model.Inthismodel,weconsiderthepipeattributes(quality,diameter,age),maintenancecost,valvereplacementcost,andannualaveragepressure.Basedonvariableselectionandprincipalcomponentanalysisresults,weextractedthreemainprinciplecomponents—thepipeattributeprincipalcomponent(PAPC),operationmanagementprincipalcomponent,andwaterpressureprincipalcomponent.Ofthese,wefoundPAPCtohavethemostinfluence.Usingprincipalcomponentregression,weestablishedanLRLFmodelwithnodetectableserialcorrelations.TheadjustedR2andRMSEvaluesofthemodelwere0.717and2.067,respectively.Thismodelrepresentsapotentiallyusefultoolforcontrollingleakageratefromthemacroscopicviewpoint.
简介:Thispaperprovidesanumericalanalysismodelofunsteadyheattrans-ferinpiston-linersetofaninternalcombustionengine.Themodelsimulatestheun-steadyheattransferprocessamongthecombustionmixture,pistonset,lubricantfilm,linerandcoolantinawholeenginecycle,andcanpredictthetemperaturefluc-tuationanddistributiononpistoncrown,innersurfaceofliner,pistonringandthelubricantfilm.Acomputerprogramisdevelopedtocalculatetheunsteadyheattrans-ferprocessofpiston-linersysteminawater-cooleddieselengine.
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简介:调查高速度的润滑油的尖接触球轴承的笼子稳定性,笼子的一个动态模型根据Guptas和Meeks工作被开发。模型能与自由的所有六度在油润滑油下面模仿笼子运动。特别地,模型介绍油电影抑制并且磁滞现象抑制,并且作为有瑕疵的有弹性的接触处理碰撞接触。另外,内部戒指的效果旋转速度,到在笼子稳定性上指导清理和应用负担的袖珍清理的比率被与模型一起模仿笼子运动调查。结果能为忍受参数的球的设计提供一个理论基础。
简介:CharacteristicsofR22anditsnewalternativerefrigerantR290flowingthroughadiabaticcapillarytubesareinvestigatedbasedonthehomogeneousmodel.Extensiveflowvariablesalongtubelengthsuchaspressure,temperature,viscosity,velocity,Reynoldsnumber,frictionfactorandvaporqualityetcarecomparedbetweenthetwofluidsunderthesameoperatingcondition.Twocasesareconsidered,namely,eitherthesametubelengthorthesamemassflowrateasinletcondition.TheresultsshowthatthemassflowrateinthecapillarytubeofR290is40%lowerthanthatofR22duetothedifferencesofphysicalpropertiesbetweenthetwofluids.Further,aparametricanalysisisperformedanditappearsthateffectsofgeometricandthermodynamicparametersonmassflowrateofR290areweakerthanthatofR22.Whenthecondensingtemperatureisincreasedfrom40℃to50℃,themassflowrateforR22isincreasedby16%,whiletheincreasingrateforR290is13%.