简介：Three-dimensional(3D)printing(3DP)isarapidprototypingtechnologythathasgainedincreasingrecognitioninmanydifferentfields.Inherentaccuracyandlow-costpropertyenableapplicabilityof3DPinmanyareas,suchasmanufacturing,aerospace,medical,andindustrialdesign.Recently,3DPhasgainedconsiderableattentioninthemedicalfield.Theimagedatacanbequicklyturnedintophysicalobjectsbyusing3DPtechnology.Theseobjectsarebeingusedacrossavarietyofsurgicalspecialties.Theshortageofcadaverspecimensisamajorprobleminmedicaleducation.However,thisconcernhasbeensolvedwiththeemergenceof3DPmodel.Custom-madeitemscanbeproducedbyusing3DPtechnology.Thisinnovationallows3DPuseinpreoperativeplanningandsurgicaltraining.Learningisdifficultamongmedicalstudentsbecauseofthecomplexanatomicalstructuresoftheliver.Thus,3Dvisualizationisausefultoolinanatomyteachingandhepaticsurgicaltraining.However,conventionalmodelsdonotcapturehapticqualities.3DPcanproducehighlyaccurateandcomplexphysicalmodels.Manytypesofhumanoranimaldifferentiatedcellscanbeprintedsuccessfullywiththedevelopmentof3Dbio-printingtechnology.Thisprogressrepresentsavaluablebreakthroughthatexhibitsmanypotentialuses,suchasresearchondrugmetabolismorliverdiseasemechanism.Thistechnologycanalsobeusedtosolveshortageoforgansfortransplantinthefuture.

简介：Partorientationisoneoftheimportantfactorsinmanufacturingwiththreedimensionalprinting(3DP)ofrapidprototypingsystem.Theminimumbuildingtime,beingachievedbythepart’sminimumbuildingheightandminimumwidthin3DP’sydirection,issetastheobjectiveofoptimizingthepartorientation.Geneticalgorithmisadoptedtofindtheminimumbuildingheightofpartsandthenergodicsearchingisusedtogettheminimumwidthofpartinydirection.Acorrespondingprogramforoptimizingpartorientationin3DPwasdeveloped.Testsshowtheproposedapproachiseffectiveandfast.

简介：Thisreportdescribesanewmethod,theself-searchingmethod,tofindeigenraysinanoceanwherethereisathree-dimensionalsoundspeedperturbationblobonauniformsoundspeedbackground.Comparedwiththetraditionalshootingmethod,thismethodcanreducethenumberofraycalcula-tionsbyabouttwoordersofmagnitude,andaneigenraycanbefoundbycom-puterprogramwithoutmanualintervention.

简介：在这篇论文，一个转变模型说出SARC(有限制状况的静态过滤器的调整)被介绍，它在理论和试穿更实际、更严密任何旋转角参数。转变过程被划分成4步：①t他原版和目标坐标能与错误被认为是观察；②严密公式第一被推出以便由四个普通的点的使用计算转变参数的第一近似，转变方程被线性化；③由SARC模型④计算七个转变参数的最可能的值和变化表明SARC的有效性，一个例子被给。

简介：Inthispaperareviewoncurrentresearchon3DCMispresented,andanalternativeapproachbyintegratingtheconceptsandtechniquesofobject-orientedmethodandComputerAidedDesign(CAD)issuggested.Throughtheapproachurbanspatialentitiesasobjectsareextracted,whicharerepresentedwithprimary3Delements(node,edge,faceandbody)andtheircombinations.Inthelightoftheconceptofobject,themethodsupportsthemultiplerepresentationofLevelofDetails(LOD).Moreimportantly,topologicalrelationshipsbetweenobjectsaredescribedsothat3Dtopologicaloperationscanbeimplemented.

简介：

简介：在这份报纸，我们与不可压缩的条件为3DMHD方程的答案考虑整齐标准。由使用一些古典不平等，我们分别地以速度地和磁场的一个部件在某些足够的条件下面获得三维的MHD方程的强壮的答案的整齐。

简介：Afinite-ratemethodisusedtosimulatethethree-dimensionalcombustionprocessinaplasmageneratorwithCH4asthefuel.ThesimulationwasrunwithRNGk-εmodeltosimulateturbulence,witheddy-dissipation-concept(EDC)modeltosimulatethecombustionandwithdiscreteordinatesmodeltosimulateradiation.Thenumericalresultsshowthattheflowfieldcharacteristicsandtheparameterdistributionsareundertheconditionofrichfuels,andtheseresultsprovidevaluableinformationwhenoptimizingtheplasmageneratordesignandorganizingitsflowfields.

简介：Considerathree-dimensionalsystemhavinganinvariantsurface.Byusingbifurcationtechniquesandanalyzingthesolutionsofbifurcationequations,theauthorsstudythespacialbifurcationphenomenaofakmultipleclosedorbitintheinvariantsurface.Thesufficientconditionsoftheexistenceofmanyclosedorbitsbifurcatefromthekmultipleclosedorbitareobtained.

简介：AbstractBackground:Surgical treatment of both-column acetabular fractures is challenging because of the complex acetabular fracture patterns and the curved surface of the acetabulum. Seldom study has compared the application of three-dimensional (3D) printing technology and traditional methods of contouring plates intra-operatively for the surgical treatment of both-column acetabular fractures. We presented the use of both 3D printing technology and a virtual simulation in pre-operative planning for both-column acetabular fractures. We hypothesized that 3D printing technology will assist orthopedic surgeons in shortening the surgical time and improving the clinical outcomes.Methods:Forty patients with both-column acetabular fractures were recruited in the randomized prospective case-control study from September 2013 to September 2017 for this prospective study (No. ChiCTR1900028230). We allocated the patients to two groups using block randomization (3D printing group, n = 20; conventional method group, n = 20). For the 3D printing group, 1:1 scaled pelvic models were created using 3D printing, and the plates were pre-contoured according to the pelvic models. The plates for the conventional method group were contoured during the operation without 3D printed pelvic models. The operation time, instrumentation time, time of intra-operative fluoroscopy, blood loss, number of times the approach was performed, blood transfusion, post-operative fracture reduction quality, hip joint function, and complications were recorded and compared between the two groups.Results:The operation and instrumentation times in the 3D printing group were significantly shorter (130.8 ± 29.2 min, t = －7.5, P < 0.001 and 32.1 ± 9.5 min, t = －6.5, P < 0.001, respectively) than those in the conventional method group. The amount of blood loss and blood transfusion in the 3D printing group were significantly lower (500 [400, 800] mL, Mann-Whitney U= 74.5, P < 0.001 and 0 [0,400] mL, Mann-Whitney U = 59.5, P < 0.001, respectively) than those in the conventional method group. The number of the approach performed in the 3D printing group was significantly smaller than that in the conventional method group (pararectus + Kocher-Langenbeck [K-L] approach rate: 35% vs. 85%; x2 = 10.4, P < 0.05). The time of intra-operative fluoroscopy in the 3D printing group was significantly shorter than that in the conventional method group (4.2 ± 1.8 vs. 7.7 ± 2.6 s; t = －5.0, P < 0.001). The post-operative fracture reduction quality in the 3D printing group was significantly better than that in the conventional method group (good reduction rate: 80% vs. 30%; x2 = 10.1, P < 0.05). The hip joint function (based on the Harris score 1 year after the operation) in the 3D printing group was significantly better than that in the conventional method group (excellent/good rate: 75% vs. 30%; x2 = 8.1, P < 0.05). The complication was similar in both groups (5.0% vs. 25%; x2 = 3.1, P = 0.182).Conclusions:The use of a pre-operative virtual simulation and 3D printing technology is a more effective method for treating bothcolumn acetabular fractures. This method can shorten the operation and instrumentation times, reduce blood loss, blood transfusion and the time of intra-operative fluoroscopy, and improve the post-operative fracture reduction quality.Clinical trail registration:No.ChiCTR1900028230; http://www.chictr.org.cn

简介：AbstractBackground:Hemifacial microsomia (HFM), which involves multiple sites with different levels of severity, is the second most common congenital craniofacial deformity after cleft lip and palate. However, three-dimensional (3D) measurements of mandibular deformities have not yet been studied in detail. The objective of this study is to investigate the method of 3D measurements of mandibular deformities in HFM patients.Methods:A total of 48 HFM patients were included in this study. All clinical treatment for patients was performed in the Plastic Surgery Hospital of the Chinese Academy of Medical Sciences at Peking Union Medical College from June 2006 to June 2020. The patients’ 3D computerized tomography scan data were processed using medical imaging software, following four iterative steps: 3D reconstruction, mirroring, differential analysis, and partition.Results:The characteristics of the mandibular bone in HFM patients are mainly presented as follows: (1) compared to the normal side, the part of the bone body that extends from the ascending ramus to the pogonion (Po-NB) is analyzed using a dynamic process: less fullness-fullness-more fullness; (2) absences were frequently observed among the angular zones, that is, the height of the ascending ramus is deficient.Conclusions:HFM is a complicated condition with numerous variations in clinical presentation. We employed both 3D image reconstruction and computerization image processing techniques to investigate asymmetrical mandibular deformity in HFM patients in detail and with great accuracy. This will be of great use to clinicians for disease management.

简介：

简介：Thedynamicstressintensityfactorofathree-dimensionalellipticcrackunderimpactloadingisdeterminedwiththefiniteelementmethod.Thecomputationresultscantakeintoaccounttheinfluenceoftimeandtheratioofthewavespeedsonthestressintensityfactor.Thepresentmethodissuitablenotonlyforthree-dimensionaldynamiccrack,butalsoforthree-dimensionaldynamiccontact.

简介：Thispaperinvestigatestheproblemofmodelingandcontrollingpursuerconvoyinthree-dimensionalspace.Theguidancelawsappliedforconvoy,thevelocitypursuit,thedeviatedpursuitandtheproportionalnavigation,steerthepursuerusingtherateofline-of-sight（LOS）betweensuccessivepursuers.Onthebasisofthedifferentialequationsfortherange,thepitchangleofLOSandtheyawangleofLOSbetweensuccessivepursuers,theguidancelawsareproposedtoderivedecentralizedcontrolstrategyforpursuerconvoy.Theresultsconcerningthepursuerconvoyarerigorouslyproven.Simulationsareconductedtodemonstratethefeasibilityandeffectivenessoftheproposedcontrolstrategy.

简介：TheauthorsdefinetheGaussmapofsurfacesinthethree-dimensionalHeisenberggroupandgivearepresentationformulaforsurfacesofprescribedmeancurvature.Furthermore,asecondorderpartialdifferentialequationfortheGaussmapisobtained,anditisshownthatthisequationisthecompleteintegrabilityconditionoftherepresentation.

简介：ＴＨＲＥＥ－ＤＩＭＥＮＳＩＯＮＡＬＭＯＤＥＬＬＩＮＧＦＯＲＬＵＢＲＩＣＡＴＩＯＮＷＩＴＨＲＥＦＥＲＥＮＣＥＴＯＨＵＭＡＮＪＯＩＮＴＳＺｈａｎＪｉｅ－ｍｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭｅｃｈａｎｉｃｓａｎｄＥｎｇｉｎｅｅｒｉｎｇ，Ｚｈｏｎ...

简介：新奇木柴堆格子结构被建议。把方法基于飞机波浪扩大(PWE)，新奇木柴堆的完全的photonic乐队差距(PBG)三维(3D)有减少的对称相对的兆兆赫(THz)photonic水晶(PC)一，face-centred-tetragonal(fct)对称被改变一些结构的参数优化，thehighest乐队差距比率能到达27.61%。比作传统的木柴堆格子，novelwoodpile格子有大量充满获得高质量的PBG的比率，哪个为生产过程的providesgreater便利。新奇木柴堆3DPC将是很THz功能的部件的promisingfor材料。

简介：AbstractPurpose:Secondary displacement represents a frequent complication of conservative treatment of fractures, particularly of the distal radius. The gap space between skin and cast may lead to a certain degree movements and this increased mobility might favor redisplacement. The aim of this study was to develop a new 3D method, to measure the gap space in all 3 geometrical planes, and to validate this new technique in a clinical setting of distal radius fractures.Methods:This study applies 3D imaging to measure the space between plaster and skin as a potential factor of secondary displacement and therefore the failure of conservative treatment. We developed and validated a new methodology to analyze and compare different forearm casts made of plaster of Paris and fiberglass. An unpaired t-test was performed to document differences between the investigated parameters between plaster of Paris and fiberglass casts. The significance level was set at p< 0.05.Results:In a series of 15 cases, we found the width of the gap space to average 4 mm, being slightly inferior on the radial side. Comparing the two different casting materials, plaster of Paris and fiberglass, we found a significantly larger variance of space under casts made of the first material (p=0.39). A roughness analysis showed also a markedly significantly higher irregularity of the undersurface of plaster of Paris as compared with fiberglass.Conclusion:This study allows for a better understanding of the nature of the "gap space" between cast and skin and will contribute to develop and improve new immobilization techniques and materials.

简介：Anewmethodformeasuring3-Drigidbodydisplacementsisproposed,inwhichtwoperpendicularbeamsareemittedontotwosensitiveplanesofPSDsleingperpendiculartoeachother.Themethodcanbeusedtomeasure1-Dor2-Ddisplacementswhenrequired.Moreover,theexperimentalresultsarepresented,whichdemonstratethatthenewmethodhashighaccuracy,fastprocessingspeed,highreliability,andeasilybeingrealized.

简介：Avortexringimpingingonathree-dimensionalbumpisstudiedusinglargeeddysimulationforaReynoldsnumberRe=4×104basedontheinitialtranslationspeedanddiameterofthevortexring.Theeffectsofbumpheightonthevorticalflowphenomenaandtheunderlyingphysicalmechanismsareinvestigated.Basedontheanalysisoftheevolutionofvorticalstructures,twotypicalkindsofvorticalstructures,i.e.,thewrappingvorticesandthehair-pinvortices,areidentifiedandplayanimportantroleintheflowstateevolution.Thecirculationoftheprimaryvortexringreasonablyelucidatessometypicalphasesofflowevolution.Furthermore,themechanismofflowtransitionfromlaminartoturbulentstatehasbeenrevealedbasedonanalysisofturbulentkineticenergy.