简介:2D/3DIsometricTransformationUsingSpring_MasSystemFanJin1MathewM.F.Yuen2QifuWang1ZhouJi11TheCADCenterofTheHuazhongUnviersityof...
简介:Theboundaryelementmethodforthemodalanalysisoffreevibrationfor3-Danisotropicstructuresusingparticularsolutionshasbeendeveloped.Thecompletepolynomialsofordertwoareusedtoconstructtheparticularsolutionsforgeneralanisotropicmaterials.Thenumericalresultsfor3-Dfreevibra-tionanalysisofanisotropiecantileverbeambythemethodpresentedisingoodagreementwiththeresultsus-ingtheRitztechnique.Foranisotropicmaterials,thenumericalresultscalculatedfromtheproposedmethodareingoodagreementwiththeresultsfromMSC.NASTRAN.
简介:Inthispaper,perturbationmethodandFourier-cosine-expansionmethodareusedtosolvea3-DnonlinearproblemofasupercavitatingflowinaninclinedfieldofgravityatlargeFroudenumbers.Byexpandingthevelocitypotentialintoapowerseriesofasmallparameter,theoriginal3-Dnonlinearproblemisreducedtoanumberof2-Dones.Thesolutionsofthefirstthreeordersarederivedindetailandexpressedintermsofthecompleteellipticintegralsofthefirstandsecondkinds.Thentheboundaryintegralequationmethodisappliedtogetthenumericalsolutionsforeachorder.Computationalresultsareprovidedforsupercavitatingflowspastconesundervariousflowconditions.
简介:Inthispaper,a3Dsourcedistributiontechniqueisusedtocalculatethecoupledmotionsbetweentwoshipswhichadvanceinthewavewiththesamespeed.Thenumericalresultsofcoupledmotionsforafrigateandasupplyshiphaveagoodagreementwiththeexperimentalresults.Basedonthe3Dcoupledmotionsoftwoships,aspectralanalysisisemployedtoclearlyobservetheeffectofspeed,clearanceandwaveheadingonthesignificantrelativemotionamplitude(SRMA)oftwoships.Themethodpresentedinthispaperwillbehelpfultoselectsuitableclearance,speedandwaveheadingforunderwayreplenishmentatsea(RAS).
简介:Thispaperpresentsanewalgorithmforgenerating3DimagesofB-repsobjectswithtrimmedsurfaceboundaries.The3Dimageisadiscretevoxel-maprepresentationwithinaCubicFrameBuffer(CFB).Thedefinitionof3Dimagesforcurve,surfaceandsolidobjectareintroducedwhichimplytheconnectivityandfidelityrequirements.AdaptiveForwardDifferencingmatrix(AFD-matrix)for1D-3Dmanifoldsin3Dspaceisdeveloped.BysettingrulestoupdatetheAFD-matrix,theforwarddifferencedirectionandstepwisecanbeadjusted.Finally,anefficientalgorithmispresentedbasedontheAFD-matrixconceptforconvertingtheobjectin3Dspaceto3Dimagein3Ddiscretespace.
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简介:Seismicdataacquiredinseabeachwasaffectedbylargevariationsinnear-surfacemedia,seriousreceiverdrifting,serioushigh-frequencynoises,heavymultiples,complexsubsurfacegeologyanddifficultiesinimaging.BGPResearchInstitute,havingworkedonthecorrespondingissuesforseveralyears,hascompletedaseriesofcomplexseabeach3Dseismicinterpretationapproachesincludingsyntheticseismiccalibrationwithdirectionalwelldata,analysisofstressfield,correlatinginterpretationwithmulti-screenmulti-linerecursion,
简介:Objective:ToevaluateandcomparethediagnosticvalueinatlantoaxialsubluxationbyCTthree-dimensional(3D)reconstruction.Methods:3Dreconstructionfimdingsof41patientswithatlantoaxiaisubluxationwereretrospectivelyanalyzed,andcomparisonsweremadeamongimagesoftransversesection,multiplanarreformorting(MPR),surfaceshadedisplay(SSD),maximumintensityproject(MIP),andvolumerendering(VR).Results:Of41patientswithatlantoaxialsubluxation,31belongedtorotarydislocation,5antedislocation,and5hinddislocation.Allthecasesshowedthedislocatedjointpanelofatlantoaxialarticulation.Fifteencasesshoweddeviationoftheodontoidprocessand8caseswideneddistancebetweenthedensandanteriorarchoftheatlas.ThedislocatedjointpanelofatlantoaxialarticulationwasmoreclearlyseenwithSSD-3Dimagingthananyothermethods.Conclusions:AtlantoaxialsubluxationcanwellbediagnosedbyCT3Dreconstruction,inwhichSSD-3Dimagingisoptimal.
简介:Airborne3DimagewhichintegratesGPS,attitudemeasurementunit(AMU),scanninglaserrangefinder(SLR)andspectralscannerhasbeendevelopedsuccessfully.ThespectralscannerandSLRusethesameopticalsystemwhichensureslaserpointtomatchpixelseamlessly.Thedistinctiveadvantageof3Dimageisthatitcanproducegeo_referencedimagesandDSM(digitalsurfacemodels)imageswithoutanygroundcontrolpoints(GCPs).ItisnolongernecessarytosurveyGCPsandwithsomesoftwaresthedatacanbeprocessedandproducedigitalsurfacemodels(DSM)andgeo_referencedimagesinquasi_real_time,therefore,theefficiencyof3Dimageis10~100timeshigherthanthatoftraditionalapproaches.Theprocessingprocedureinvolvesdecomposingandcheckingtherawdata,processingGPSdata,calculatingthepositionsoflasersamplepoints,producinggeo_referencedimage,producingDSMandmosaicingstrips. Theprincipleof3Dimageisfirstintroducedinthispaper,andthenwefocusonthefastprocessingtechniqueandalgorithm.Theflighttestsandprocessedresultsshowthattheprocessingtechniqueisfeasibleandcanmeettherequirementofquasi_real_timeapplications.
简介:为波浪领域推测的一个精确、宽角度的单程的增殖者面对大、快速的速度变化是为关于波浪方程prestack深度移植的研究的一个重要话题。基于在这篇论文介绍的最佳的可分离的近似,有前面、反的Fourier变换的混合的域算法被用来构造3D单程的波浪领域推测操作员。这个操作员在波浪号码和空间领域分开变量。当为侧面的速度变化的时间延期在空间领域被改正时,阶段移动操作在波浪数字领域被实现。单程的波浪操作符的推动回答证明数字计算与为每速度的理论值一致,表明与最佳的可分离的近似构造的操作符能被用于为小步的盒子的侧面的速度变化。SEG/EAGE模型和领域数据的成像结果显示新方法能习惯于图象建筑群结构。
简介:Inrecentyears,thevolumetricapproachof3Dreconstructionhasemergedasapowerfulclinicmethodforbiomedicalapplications.Thisapproachisbasedonavoxelrepresentedobjectwhichmaintainsmanydetailsofthesurfaceandtheinternalcon-structuresoftheoriginalbody.Becauseofahugeamountofdata,thevolumedatasettakesalargesizeofmemory,andahighprocessingspeedisrequiredinorderto