简介:Severalquadrilateralshaperegularmeshconditionscommonlyusedinthefiniteelementmethodareproventobeequivalent.Theirinfluenceonthefiniteelementinterpolationerrorandtheconsistencyerrorcommittedbynonconformingfiniteelementsareinvestigated.TheeffectoftheBi-SectionConditionanditsextendedversion(1+α)-SectionConditiononthedegeneratemeshconditionsisalsochecked.ThenecessityoftheBi-SectionConditioninfiniteelementsisunderpinnedbymeansofcounterexamples.
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简介:InCAD/CAM,meshratherthansmoothsurfaceisonlyneededsometimes.Amesh-generatingmethodfrompermanenceprincipleofCoonspatchisdeveloped.Anewmeshpointisdefinedthroughlocalsmallsubpatchandallmeshpointsarecomputedbyalinearsystemwithspecialsymmetricblocktridiagonalcoefficientmatrix.Bysimplification,thedeterminantofcoefficientmatrixisdeterminedbydeterminantsofsubmatrices.Conditionofexistenceofsolutionisgiven.Whethercoefficientmatrixissingularcanbejudgedbyasimplepolynomialfunctionwiththeeigenvalueofsubmatrixasvariable.Numericalexamplesdemonstratetheeffectsofshapeparameters.
简介:TheBeijing-basedSyntheticRubberPlantoftheYanhuaPetrochemicalCo.Ltd.isChina’slargestenterpriseproducingsyntheticrubber.Bu...
简介:Thissurveyreviewstherecentdevelopmentofgradientdomainmeshdeformationmethod.Differenttootherdeformationmethods,thegradientdomaindeformationmethodisasurface-based,variationaloptimizationmethod.Itdirectlyencodesthegeometricdetailsindifferentialcoordinates,whicharealsocalledLaplaciancoordinatesinliterature.BypreservingtheLaplaciancoordinates,themeshdetailscanbewellpreservedduringdeformation.DuetothelocalityoftheLaplaciancoordinates,thevariationaloptimizationproblemcanbecastedintoasparselinearsystem.Fastsparselinearsolvercanbeadoptedtogeneratedeformationresultinteractively,oreveninreal-time.Thenonlinearnatureofgradientdomainmeshdeformationleadstothedevelopmentoftwocategoriesofdeformationmethods:linearizationmethodsandnonlinearoptimizationmethods.Basically,thelinearizationmethodsonlyneedtosolvethelinearleast-squaressystemonce.Theyarefast,easytounderstandandcontrol,whilethedeformationresultmightbesuboptimal.Nonlinearoptimizationmethodscanreachoptimalsolutionofdeformationenergyfunctionbyiterativeupdating.Sincethecomputationofnonlinearmethodsisexpensive,reduceddeformablemodelsshouldbeadoptedtoachieveinteractiveperformance.Thenonlinearoptimizationmethodsavoidtheuserburdentoinputtransformationatdeformationhandles,andtheycanbeextendedtoincorporatevariousnonlinearconstraints,likevolumeconstraint,skeletonconstraint,andsoon.Wereviewrepresentativemethodsandrelatedapproachesofeachcategorycomparativelyandhopetohelptheuserunderstandthemotivationbehindthealgorithms.Finally,wediscusstherelationbetweenphysicalsimulationandgradientdomainmeshdeformationtorevealwhyitcanachievephysicallyplausibledeformationresult.
简介:Itisachallengingproblemofsurface-baseddeformationtoavoidapparentvolumetricdistortionsaroundlargelydeformedareas.Inthispaper,weproposeanewrigidityconstraintforgradientdomainmeshdeformationtoaddressthisproblem.Intuitivelytheproposedconstraintcanberegardedasseveralsmallcubesdefinedbythemeshverticesthroughmeanvaluecoordinates.Theuserinteractivelyspecifiesthecubesintheregionswhicharepronetovolumetricdistortions,andtherigidityconstraintscouldmakethemeshbehavelikeasolidobjectduringdeformation.Theexperimentalresultsdemonstratethatourconstraintisintuitive,easytouseandveryeffective.
简介:Syntheticapertureimaginglidarisanactivenewimagingsystem,whichcanofferafinerazimuthresolutionthantheSARsystem.Anindoorsystemofsyntheticapertureimaginglidarisgiven,whichisademonstrationaboutsyntheticaperturetoimagerotatingobjects.Firstly,thebasicprincipleisintroduced.Then,thebasicmethodandkeytechniquesareanalyzed.Afterthatanimprovedsystemisgivenwiththetransmittingandthereceivinglensapartfromeachotherwhichcaneliminatetheinterferenceefficiently.Finally,theblockdiagramandtheresultofimagingsystemaregiven,whichprovethevalidityofthesystemandthefeasibilityofthesyntheticaperturetechniquesinopticaldomain.
简介:不同液体的混乱混合生产旋绕的结构到分开这些液体的接口。为能溶合的液体(是这里考虑了),这个接口被定义为50%集体集中isosurface。为导致的冲击波(Richtmyer-Meshkov)不稳定性,我们发现接口当计算网孔被精制,逐渐地复杂。如果Kolmogorov规模相对网孔是小的,这界面的混乱被粘性,或由计算网孔割掉。在集成的接口统计的政体,我们然后检验混合,即集中统计,由质量调整了散开。为比统一显著地大的Schmidt数字,典型地代表液体或稠密的血浆,另外的网孔精炼通常被需要克服数字集体散开并且完成混合问题的一个集成的答案。然而,与前面追踪的利益并且与一个算法,那允许有限接口散开,我们能在Schmidt数字一致地保证集中。我们证明不同答案源于Schmidt数字的变化。我们建议潜水艇格子粘性和可能在现实主义的格子层次允许集成的答案的集体散开parameterizations。
简介:Solution-drivenmeshadaptationisbecomingquitepopularforspatialerrorcontrolinthenumericalsimulationofcomplexcomputationalphysicsapplications,suchasclimatemodeling.Typically,spatialadaptationisachievedbyelementsubdivision(hadaptation)withaprimarygoalofresolvingthelocallengthscalesofinterest.Asec-ond,less-popularmethodofspatialadaptivityiscalled'meshmotion'(radaptation);thesmoothrepositioningofmeshnodepointsaimedatresizingexistingelementstocapturethelocallengthscales.Thispaperproposesanadaptationmethodbasedonacombinationofbothelementsubdivisionandnodepointrepositioning(rhadaptation).Bycombiningthesetwomethodsusingthenotionofamobilityfunction,theproposedapproachseekstoincreasetheflexibilityandextensibilityofmeshmotionalgorithmswhileprovidingasomewhatsmoothertransitionbetweenrefinedregionsthanispro-ducedbyelementsubdivisionalone.Further,inanattempttosupporttherequirementsofaverygeneralclassofclimatesimulationapplications,theproposedmethodisde-signedtoaccommodateunstructured,polygonalmeshtopologiesinadditiontothemostpopularmeshtypes.
简介:Freesurfaceflowproblemsinvolvinglargefreemotionsareanalysedusingfiniteelementtechniques.InsolvingtheseproblemsanArbitraryLagrangian-Eulerian(ALE)kinematicaldescriptionofthefluiddomainisadopted,inwhichthenodalpointscanbedisplacedindependentlyofthefluidmotion.Anewmeshtracingmethodisproposedinthispaper.Toconfirmtheeffectivenessofthenewmethod,solitarywavepropagationisanalysedandthenumericalresultsarecomparedwiththeanalyticalresults.ThebehaviouroftheviscousfluidflowwithafreesurfaceisexpressedbytheunsteadyNavier-Stokesequation.Fornumericalintegrationintimethevelocitycorrectionfractionalstepmethodisused.
简介:Thispaperintroducesthemethodofsupportvectormachine(SVM)intothefieldofsyntheticearthquakepre-diction,whichisanon-linearandcomplexseismogenicsystem.Asanexample,weapplythismethodtopredictthelargestannualmagnitudefortheNorthChinaarea(30°E-42°E,108°N-125°N)andthecapitalregion(38°E-41.5°E,114°N-120°N)onthebasisofseismicityparametersandobservedprecursorydata.ThecorrespondingpredictionratesfortheNorthChinaareaandthecapitalregionare64.1%and75%,respectively,whichshowsthatthemethodisfeasible.