简介:ThispaperextendstheSPHmethodtogassimulation.TheSPH(SmoothedParticlesHydrodynamics)methodisthemostpopularmethodofflowsimulation,whichiswidelyusedinlarge-scaleliquidsimulation.However,itisnotfoundtoapplytogassimulation,sincethosemethodsbasedonSPHcan’tbeusedinreal-timesimulationduetotheirenormousparticlesandhugecomputation.ThispaperproposesamethodforgassimulationbasedonSPHwithasmallnumberofparticles.Firstly,themethodcomputesthepositionanddensityofeachparticleineachpoint-in-time,andoutlinestheshapeofthesimulatedgasbasedonthoseparticles.Secondlythemethodusesthegridtechniquetorefinetheshapewiththediffusionofparticle’sdensityunderthecontrolofgrid,andgetmorelifelikesimulationresult.Eachgridwillbeassigneddensityaccordingtotheparticlesinit.Thedensitydeterminesthefinalappearanceofthegrid.Forensuringthenaturaltransitionofthecolorbetweenadjacentgrids,wegiveadiffuseprocessofdensitybetweenthesegridsandassignappropriatevaluestovertexesofthesegrids.Theexperimentalresultsshowthattheproposedmethodcangivebettergassimulationandmeettherequestofreal-time.
简介:Particlebasedmethodscanbeusedforboththesimulationsofsolidandfluidphasesinmultiphasemedium,suchasthediscrete-elementmethodforsolidphaseandthesmoothedparticlehydrodynamicsforfluidphase.Thispaperpresentsacomputationalmethodcombiningthesetwomethodsforsolid-liquidmedium.ThetwophasesarecoupledbyusinganimprovedmodelfromareportedLagrangian-Eulerianmethod.Thetechniqueisverifiedbysimulatingliquid-solidflowsinatwo-dimensionallid-drivencavity.
简介:Thepredictionaccuracyofasimulationmethodislimitedbyitstheoreticalbackground.Thisfactcanleadtodisadvantagesregardingthesimulationqualitywheninvestigatingsystemsofhighcomplexity,e.g.containingcomponentsshowingafairlydifferentbehavior.Toovercomethislimitation,co-simulationapproachesareusedmoreandmore,combiningtheadvantagesofdifferentsimulationdisciplines.Thatiswhyweproposeanewstrategyforthedynamicsimulationofcuttingprocesses.ThemethodcouplesLagrangianparticlemethods,suchasthesmoothedparticlehydrodynamics(SPH)method,andmultibodysystem(MBS)toolsusingco-simulations.Wedemonstratethecapabilityofthenewapproachbyprovidingsimulationresultsofanorthogonalcuttingprocessandcomparingthemwithexperimentaldata.
简介:Inthisstudy,theNorthChinaseismicregionwasselectedasthestudyarea,andevaluationofseismichazardusingthespatialsmoothingseismicitymodelwasperformed.Firstly,thestudyareaisdividedintogrids,andsomeparameters(e.g.b-value,M0,Mu,azimuthandM-Lrelationship)foreachseismotectonicmodelwereassigned.Secondly,usingellipticalsmoothingbasedonaseismotectonicbackgroundmodel,thestatisticalearthquakeincidencerateineachgridissuccessivelycalculated.Lastly,therelevantgroundmotionattenuationrelationshipischosentoassessseismichazardofgeneralsites.Themapsforthedistributionofhorizontalpeakgroundaccelerationwith10%probabilityofexceedancein50yearswereobtainedbyusingtheseismichazardanalysismethodbasedongridsource.Thisseismicitymodelsimplifiesthemethodologyofprobabilisticseismichazardanalysis,especiallyappropriateforthoseplaceswhereseismictectonicsisnotyetclearlyknown.Thismethodcanprovidevaluablereferencesforseismiczonationandseismicsafetyassessmentforsignificantengineeringprojects.
简介:Thenumericalmodellingoftheinteractionsbetweenwaterwavesandfloatingstructuresissignificantfordifferentareasofthemarinesector,especiallyseakeepingandpredictionofwave-inducedloads.SeakeepinganalysisinvolvingsevereflowfluctuationsisstillquitechallengingevenfortheconventionalRANSmethod.Particlemethodhasbeenviewedasalternativeforsuchanalysisespeciallythoseinvolvingdeformableboundary,wavebreakingandfluidfragmentationaroundhullshapes.Inthispaper,theweaklycompressiblesmoothedparticlehydrodynamics(WCSPH),afullyLagrangianparticlemethod,isappliedtosimulatethesymmetricradiationproblemforastationarybargetreatedasaflexiblebody.Thisiscarriedoutbyimposingprescribedforcedsimpleharmonicoscillationsinheave,pitchandthetwo-andthree-nodedistortionmodes.Theresultant,radiationforcepredictions,namelyaddedmassandfluiddampingcoefficients,arecomparedwithresultsfrom3-Dpotentialflowboundaryelementmethodand3-DRANSCFDpredictions,inordertoverifytheadoptedmodellingtechniquesforWCSPH.WCSPHwerefoundtobeinagreementwithmostresultsandcouldpredictthefluidactionsequallywellinmostcases.
简介:肝胞虫疾病是在农场和牧剧区域的普通寄生疾病,它严重影响人的健康。基于这疾病的CT成像特征,为肝分割的一条反复的途径和胞虫损害抽取同时被建议。在每次重复,我们的算法由二主要的步组成:1)根据在肝和胞虫的自定义象素种子,损害,Gaussian概率模型试穿和弄平的贝叶斯的分类被使用得到肝和损害的起始的分割;2)用priori形状力量地的参量的活跃轮廓模特儿被收养精制起始的分割。我们由不同病人的CT片的肝和胞虫损害分割的实验在建议算法有效性上做主观、客观的评估。与地面真相手册分割结果比较,试验性的结果显示我们的方法的有效性分割肝和胞虫损害。