简介：Predictingpotentialchangesingroundwatersalinityinlow-lyingcoastalregionsduetoclimatechangeisimportant,wherecoastalvegetationisabundant,successioncompetitionbetweenhalophytesandglycophytesplaysasignificantroleinthesalinitybudget.Sealevelriseenhancessalinityintrusion,contributinganadditionaldimensiontovegetationcompetition.Anewsimulationmodelknownasmangrove-hardwoodhammockmodelcoupledwithsaturated-unsaturatedtransport(MANTRA)hasrecentlybeendevelopedbytheauthorstosimulategroundwatersalinityregimesinthepresenceofvegetationcompetition,subjecttoclimatechange.MANTRAisbaseduponlinkingtwoexistingUnitesStatesgeologicalsurvey(USGS)simulationmodelsknownasmangrove-hardwoodhammockmodel(MANHAM)andsaturated-unsaturatedtransport(SUTRA).MANHAMsimulatestheevolutionofvegetationsuccessionsubjecttochanginggroundwatersalinity.SUTRAsimulatessaturatedandunsaturatedtransportofsolutesandsalinityingroundwatergivenseasalinity.MANTRAimprovesthesimulationrobustnesstosimultaneouslysimulategroundwaterhydrology,salinityandcoastalvegetationsuccessionsubjecttosealevelrise.Somesimulationresultswillbepresentedtodemonstratetheimpactofsealevelriseoncoastalvegetationsuccessionandgroundwatersalinity.

简介：

简介：Contact-impactprocessesoccuratmostcasesinmultibodysystems.Sub-periodsandsub-regionalmethodsarefrequentlyusedrecently,anddifferentcoordinatesareintroducedinbothoftheapproaches.However,thesub-regionalmethodseemstobemoreeffective.Floatingframeofreferenceformulationiswidelyusedforcontacttreatment,whichdescribesdisplacementsbytherigidbodymotionandasmallsuperposeddeformation,andthecoordinatesdepictingthedeformationincludefiniteelementnodalcoordinatesandmodalcoordinates,theformerdealswiththecontact/impactregion,andthelaterdescribesthenon-contactregion.Inthispaper,freeinterfacesubstructuremethodisusedinmodeling,andthedynamicequationofasinglebodyisderived.Then,usingtheLagrangeequationofthefirstkind,thedynamicequationsofmultibodysystemsareestablished.Furthermore,contact-impactareasaretreatedthroughadditionalconstraintequationsandLagrangemultipliers.Usingsuchapproach,thenumberofsystemcoordinatesandthedimensionsofmassmatrixaresignificantlyreducedwiththemodaltruncation,thereforebothoftheefficiencyandaccuracyareguaranteed.Finiteelementmethodinthelocalcontactregioncandealwithcontact/impactbetweenarbitrarilycomplexinterfaces,whereas,additionalcontactconstraintsusedinthenodaldescriptionregioncanavoidthecustomizedparametersthatareusedinthecontinuousforcemodel.

简介：Aerodynamicforcesanddynamicperformancesofrailwayvehiclesarecoupledandaffectedbyeachother.Ontheonehand,aerodynamicforceschangethedisplacementsofatrain.Ontheotherhand,displacementsaffectaerodynamicforces.Basedonvehicle-trackcouplingdynamicsandaerodynamics,anumericalapproachtotheinteractionbetweenairflowandahigh-speedtrainispresentedinthispaper.Aerodynamicforcesanddynamicperformancesofahigh-speedtrainsubjectedtocrosswindwerenumericallysimulated.Resultsshowedthattheinteractionbetweenairflowandahigh-speedtrainhasasignificantinfluenceondisplacementsandaerodynamicforcesoftheheadcoach.Therefore,itisnecessarytoconsidertheinteractionbetweenairflowandahigh-speedtrainsubjectedtocrosswind.

简介：Thepredictionaccuracyofasimulationmethodislimitedbyitstheoreticalbackground.Thisfactcanleadtodisadvantagesregardingthesimulationqualitywheninvestigatingsystemsofhighcomplexity,e.g.containingcomponentsshowingafairlydifferentbehavior.Toovercomethislimitation,co-simulationapproachesareusedmoreandmore,combiningtheadvantagesofdifferentsimulationdisciplines.Thatiswhyweproposeanewstrategyforthedynamicsimulationofcuttingprocesses.ThemethodcouplesLagrangianparticlemethods,suchasthesmoothedparticlehydrodynamics(SPH)method,andmultibodysystem(MBS)toolsusingco-simulations.Wedemonstratethecapabilityofthenewapproachbyprovidingsimulationresultsofanorthogonalcuttingprocessandcomparingthemwithexperimentaldata.

简介：

简介：Anewefficientmeshlessmethodbasedontheelement-freeGalerkinmethodisproposedtoanalyzethestaticdeformationofthinandthickplatestructuresinthispaper.Usingthenew3Dshell-likekinematicsinanalogytothesolid-shellconceptofthefiniteelementmethod,discretizationiscarriedoutbythenodeslocatedontheupperandlowersurfacesofthestructures.Theapproximationofallunknownfieldvariablesiscarriedoutbyusingthemovingleastsquares(MLS)approximationschemeinthein-planedirections,whilethelinearinterpolationisappliedthroughthethicknessdirection.Thus,differentboundaryconditionsaredefinedonlyusingdisplacementsandpenaltymethodisusedtoenforcetheessentialboundaryconditions.TheconstrainedGalerkinweakform,whichincorporatesonlydisplacementdegreesoffreedom(d.o.f.s),isderived.Amodified3Dconstitutiverelationshipisadoptedinordertoavoidoreliminatesomeself-lockingeffects.Thenumericefficiencyoftheproposedmeshlessformulationisillustratedbythenumericexamples.