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简介:Thankstothedevelopmentofmetallographicandopticaltechniques,thequantitativecharacterisationofthegeometryofroughsurfaceshasbecomeveryusefulinpracticalapplications.Today,numerousdifferentmethodsareavailablefordeterminingthreedimensionalco-ordinates,linearprofilesorheightcontourstoareasonabledegreeofaccuracyandwithinanacceptabletimeframe,andforevaluatingsuchdata.Inthisarticle,theuseofsuchtechniquesinthefieldoffractographyisdemonstratedwithreferencetoanumberofcasestudiesdealtwithbytheauthor'sownteam,supplementedbyseveralexamplesfromotherresearchgroups.Thefollowingexamplesarediscussed:Inaceramicmaterialdifferentfracturepathswerediscernedcorrespondingtodifferenttesttemperatures.Inhardmetals,itwasshownthathoththesub-criticalandsupercriticalpropagationofcracksoccurreddalongthesamepath.Frommeasurementsoftheproportionoffracturesurfacesoccurringalongandinthevariousdifferentphasespresentandthedepthofdimplesoccurringduringductilefractureinthebinderphase,thefractureenergyofEC-Co-hardalloyswithdifferentcobaltcontentsandtungstencarbidegrainsizeswascalculatedandfoundtobeinexcellentagreementwithactualexperimentalresults.Inthecaseofceramicfibre-aluminiummatrixcpmpositematerials,bymeasuringthebeightdistributionofthepositionsoffractureofthefibres,theloadtransferintheregionofthefracturesurfacewasdetermined.withthisinformationamodelwasdevelopedwhichexplainsthesignificantvariationinstrengthofthesematerialsFinally,amodelwasdevelopedformetallicmaterialsusingwhich,fromtheexperimentallydetermineddistributionsoftheheightandinclinationofthefracturefacets,thestressintensityofroughnessinducedcrackclosingcouldheaccuratelypredicted.
简介:客观:为了选择腰部的transpedicular的一个合适的方法,在三个方法之中在不同腰部的层次拧紧固定(Roy-Camille“s方法,Magerl”s方法和杜“smethod)在中国人口。方法:三维(3-D)图象与被电子横梁CT扫描的42个成年腰部的片断的图象数据被重建。腰部的小花梗螺丝钉固定的三个方法在3-D上被模仿重建的图象和植入小花梗螺丝钉的参数被测量。结果:在从入口点的距离有统计上重要的差别到在三个方法之间的小花梗轴(P<0.001)。Thedistances由“s方法从L1是最短的到L4,并且距离测量了byMagerl”的杜测量了s方法在L5是最短的(P<0.05)。从L1没有重要差别到L2(P>0.05),但是对在插入TSA(横向的节角度)的安全范围的L5的从L3的重要差别在三个方法之间被发现(P<0.05)。从L3到L4,TSA的插入的安全范围由杜测量了“s”和Magerls方法比那测量byRoy-Camille显著地大“s方法(P<0.05),但是他们之间没有重要差别(P>0.05)。AtL5,TSA的插入的安全范围由Magerl测量了“s方法在三个方法之中是最大的(P<0.05)。结论:在三个方法之中,杜“因为它到小花梗轴的从入口点的距离最短,TSA的安全范围最大,s方法是从L1toL4的最好的选择;Magerl“s方法能从L3被使用到L5并且是在L5的最好的选择;Roy-Camille”s方法在L1和L2是适用的。
简介:Objective:Tostudythefeasibilityofmulti-slicespiralcomputedtomography(MSCT)3-dimensionalreconstruc-tiontechniqueinassistingcervicalpediclescrewfixation(PSF)anddouble-doorlaminoplastytotreatmulti-segmen-taldegenerativespinalstenosiswithtraumaticinstability(MDSTI)oflowercervicalspine.Methods:FromSeptember2006toAugust2007,PSFcombinedwithdouble-doorlaminoplastywasperformedin9patientswithMDSTIoflowercervicalspine.MSCT3-dimensionalreconstructiontechniques,includingvolumerendering(VR)andmulti-planarreconstruction(MPR),wereusedtoassistpreoperativediagnosisandmeasurementtoguidetheprocedure.MPRwasperformedafteroperation.Incoronalview,thedegreeofscrewperforationwasmea-suredpreciselyandthedifferentpositionsofpediclescrewsweredividedintothreegradesaccordingtoRichter'smethod.Inaxialview,thecanalsagittaldiameterandtrans-verseareaofeverylaminoplastylevelweremeasured.Results:NinepatientswithMDSTIoflowercervicalspineunderwentPSF(total44screws).AccordingtotheclassificationofRichter,72.7%(32/44)wasinGrade1and27.3%(12/44)wasinGrade2.NoscrewperforationoccurredinGrade3andnoscrewrevisionwasdoneformisplacement.Noiatrogenicdamagewasobserved.Double-doorlaminoplastywasperformedintotal42volumes.Thepost-operativesagittaldiameterandtransverseareaofcervicalspinalcanalweresignificantlyincreased(P<0.05).Theconfi-denceintervalsofmeanincreasedratiowere23.43%-40.65%insagittaldiameterand23.18%-42.07%intransversearea.Sixmonthsafterlaminoplasty,basedonMSCTaxialview,completeunionbetween"opendoor"andallograftbonewasobtainedin76.19%ofvolumes(32/42),andallograftbonewasabsorbedpartlyin23.81%(10/42).Asolidunioninbilateralgutterswasachievedinallcases.Theywerefollowedupfrom6monthsto1year(mean7.8months).Post-operativeneuralfunctionrecoveryintwocasesimproved2ASIAgrade,5casesi