学科分类
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106 个结果
  • 简介:Asapromisingtechniquetoenhancethespatialresolutionofremotesensingimagery,sub-pixelmappingisprocessedbasedonthespatialdependencetheorywiththeassumptionthatthelandcoverisspatiallydependentbothwithinpixelsandbetweenthem.Thespatialattractionisusedasatooltodescribethedependence.First,thespatialattractionsbetweenpixels,subpixel/pixelspatialattractionmodel(SPSAM),aredescribedbythemodifiedSPSAM(MSPSAM)thatestimatestheattractionsaccordingtothedistributionofsub-pixelswithinneighboringpixels.Thenamixedspatialattractionmodel(MSAM)forsub-pixelmappingisproposedthatintegratesthespatialattractionsbothwithinpixelsandbetweenthem.AccordingtotheexpressionoftheMSAMmaximumisingthespatialattraction,thegeneticalgorithmisemployedtosearchtheoptimumsolutionandgeneratethesub-pixelmappingresults.ExperimentsshowthatcomparedwithSPSAM,MSPSAMandpixelswappingalgorithmmodifiedbyinitializationfromSPSAM(MPS),MSAMcanprovidehigheraccuracyandmorerationalsub-pixelmappingresults.

  • 标签: 映射空间 子像素 景点 整合 高空间分辨率 映射模型
  • 简介:Ignitionmodelsoftestedmaterialhaveimportantsignificancetofireprevention.Inordertoknowheattransferofthermalthinmaterialinfiredisaster,startingfromthelawofconservationofenergy,simplifyingheatcapacityintoaconstantaccordingtoDulong-Petitlaw,andthreecalculationformulasofignitiontimeofthermalthinmaterialinaconstantheatfluxwererespectivelyobtainedundertheconditionsofignoringheatloss,linearprocessingheatlossandconsideringthermalradiation.Therelationbetweentheignitiontimeandthethermalcurrentintensitywasdiscussed.

  • 标签: THERMAL THIN material heat FLUX THERMAL
  • 简介:Intheproductionofpipesbyhotextrusionmethod,billetsshouldbeheatedtoacertaintemperaturebeforehotextrusionbyinductionheating.ThesegmentedlinersintheinductionfurnacecanpossiblyaffectthecircumferentialJouleheatgeneration,thusleadingtoanuneventemperaturefield.Thecommonlyusedmagneticfluxconcentrators(MFC)canincreasethetemperatureonbothendsofthebillet.Inthispaper,thepossibleeffectoflinersandthefactorsaffectingtheutilizationoftheMFC,includingthepermeability,dimensionandposition,areallnumericallystudiedanddetermined.

  • 标签: 热挤压法 钢坯 衬垫 焦耳 热诱导 感应加热
  • 简介:Itisveryimportanttomeasurelocaldeformationsforanin-depthunderstandingofmechanicalpropertiesandfracturemechanismofstructuralandfunctionalmaterials.Inthispaper,differenttypesofmodelgridfabricationmethodsandmanytypesofelectronMoiremethodsusinganelectronbeamdrawingsystem,ascanningelectronmicroscopeorafocusionbeamarereported,togetherwiththeirapplicationsinthemeasurementofdeformationsoccurringinvariousengineeringsandmaterialsscienceresearch.

  • 标签: 电子束 莫尔法 扫描电子显微镜 变形测量 聚焦离子束 断裂机制
  • 简介:装载的风是为控制大跨度的房顶结构的设计的最重要的负担之一。相等的静态的风负担,能通常瞄准决定特定的回答,被结构的设计者广泛地使用。为对多反应适用的相等的静态的风负担的一个方法在这份报纸被建议。相应于特别山峰回答的一个修改loadresponse-关联(纵向冗余码校验)方法被介绍,并且类似算法实现了因为组反应被描述。算法的主要想法是二回答能被放进一个组如果一回答的价值接近另外的反应的,当结构受到瞄准另外的反应的相等的静态的风负担时。基于修改纵向冗余码校验,组织反应方法被提出到装载的构造等价物静电干扰风。这种技术能同时为一些组织回答复制山峰回答。验证它的计算精确性,方法被用于实际大跨度的房顶结构。计算结果看那在一样的组的回答的类似什么时候高,有高精确性的相等的静态的风负担和相等的静电干扰的合理大小弯屈分发能被完成。

  • 标签: 静风荷载 改良法 等效 分组 大跨度屋盖结构 基础
  • 简介:射击peening是由在金属性的材料的表面附近产生压缩剩余应力增加疲劳生活和抵抗到腐蚀疲劳的一个广泛地使用的表面处理方法,裂开,等等。压缩剩余应力和凹部侧面是重要因素评估射击peening过程的有效性。在这份报纸,最大的压缩剩余应力和凹部的最大的深度上的无尺寸的参数的影响被调查。第一,处理影响最大的压缩剩余压力和凹部的最大的深度的参数的无尺寸的关系被维的分析方法推出。第二,无尺寸的变量上的每个无尺寸的参数的影响被有限元素方法调查。而且,相关实验公式基于模拟结果为每个无尺寸的参数被给。最后,比较被做,好同意在模拟结果和实验公式之间被发现,它证明一条有用途径为分析每个单个参数的影响在这份报纸被提供。

  • 标签: 量纲分析方法 喷丸硬化 有限元法 压缩残余应力 无量纲参数 表面处理方法
  • 简介:TheElNino-SouthernOscillation(ENSO)ismodulatedbymanyfactors;mostpreviousstudieshaveemphasizedtherolesofwindstressandheatfluxinthetropicalPacific.Freshwaterflux(FWF)isanotherenvironmentalforcingtotheocean;itseffectandtherelatedoceansalinityvariabilityintheENSOregionhavebeenofincreasedinterestrecently.Currently,accuratequantificationsoftheFWFrolesintheclimateremainchallenging;therelatedobservationsandcoupledocean-atmospheremodelinginvolvelargeelementsofuncertainty.Inthisstudy,weutilizedsatellite-baseddatatorepresentFWF-inducedfeedbackinthetropicalPacificclimatesystem;wethenincorporatedthesedataintoahybridcoupledocean-atmospheremodel(HCM)toquantifyitseffectsonENSO.AnewmechanismwasrevealedbywhichinterannualFWFforcingmodulatesENSOinasignificantway.Asadirectforcing,FWFexertsasignificantinfluenceontheoceanthroughseasurfacesalinity(SSS)andbuoyancyflux(QB)inthewestern-centraltropicalPacific.TheSSSperturbationsdirectlyinducedbyENSO-relatedinterannualFWFvariabilityaffectthestabilityandmixingintheupperocean.Atthesametime,theENSO-inducedFWFhasacompensatingeffectonheatflux,actingtoreduceinterannualQBvariabilityduringENSOcycles.TheseFWF-inducedprocessesintheoceantendtomodulatetheverticalmixingandentrainmentintheupperocean,enhancingcoolingduringLaNinaandenhancingwarmingduringElNino,respectively.TheinterannualFWFforcing-inducedpositivefeedbackactstoenhanceENSOamplitudeandlengthenitstimescalesinthetropicalPacificcoupledclimatesystem.

  • 标签: 热带太平洋 南方涛动 水通量 变异 混合海气耦合模式 调制
  • 简介:Asimplifiedmultisupportresponsespectrummethodispresented.Thestructuralresponseisasumoftwocomponentsofastructurewithafirstnaturalperiodlessthan2s.Thefirstcomponentisthepseudostaticresponsecausedbytheinconsistentmotionsofthestructuralsupports,andthesecondisthestructuraldynamicresponsetogroundmotionaccelerations.Thismethodisformallyconsistentwiththeclassicalresponsespectrummethod,andtheeffectsofmultisupportexcitationareconsideredforanymodalresponsespectrumormodalsuperposition.Iftheseismicinputsateachsupportarethesame,thesupportdisplacementscausedbythepseudostaticresponsebecomerigidbodydisplacements.Theresponsespectruminthecaseofmultisupportexcitationsthenreducestothatforuniformexcitations.Inotherwords,thismultisupportresponsespectrummethodisamodificationandextensionoftheexistingresponsespectrummethodunderuniformexcitation.Moreover,mostofthecoherencycoefficientsinthisformulationaresimplifiedbyapproximatingthegroundmotionexcitationaswhitenoise.Theresultsindicatethatthissimplificationcanreducethecalculationtimewhilemaintainingaccuracy.Furthermore,theinternalforcesobtainedbythemultisupportresponsespectrummethodarecomparedwiththoseproducedbythetraditionalresponsespectrummethodintwocasestudiesofexistinglong-spanstructures.Becausetheeffectsofinconsistentsupportdisplacementsarenotconsideredinthetraditionalresponsespectrummethod,thevaluesofinternalforcesnearthesupportsareunderestimated.Theseregionsareimportantpotentialfailurepointsanddeservespecialattentionintheseismicdesignofreticulatedstructures.

  • 标签: multisupport EXCITATION UNIFORM EXCITATION response spectrum
  • 简介:Thetriple-to-doublecoincidenceratio(TDCR)methodofliquidscintillationcount-ingisanabsolutemeasurementmethodofradioactivity.TheformulationoftheTDCRmethodandtheestablishedTDCRliquidscintillationcounterarepresentedinthispaper.TheNISTstandardreferencematerial(SRM)oftritiumwaterwasmeasuredtoverifytheperformanceoftheTDCRliquidscintillationcounter.

  • 标签: 氚水 液体闪烁计数器 标准化 标准参考物质 测量方法 NIST
  • 简介:Inthiswork,anovelmethodforsculpturedsurfacesubdivisiontoimprovethemachinery'sabilityandefficiencyin5-axisCNCmachiningcomplexsurfaceisintroduced.Themethodsubdividesautomaticallyamonolithicconvexorconcaveorsimultaneouslycomplexsculpturedsurfaceintoanumberofsurfacepatchesandachievesthegoalofsimilarnormaldirectionsandsmalldifferencebetweenthecurvaturesineverypatchbyusingweightfuzzyclusteralgorithmwhichtakesthecurvaturesandnormalvectorsofthesculpturedsurfaceintoaccountsimultaneously.TheinclinationanglevariationbetweeneverytwoCutterContactPoints(CCPoints)isdecreasedineverypatchtoavoidlarge-anglerotationoftooltosavemachiningtimewhenaflat-endmillisused.Thisworkcontributestoautomating5-axisCNCtoolpathgenerationforsculpturedpartmachiningandformingafoundationforfurtherresearch.

  • 标签: 复杂曲面 细分 5轴数控加工 模糊聚类算法 加工时间 倾角变化
  • 简介:Thispaperproposesanovelexemplar-basedmethodforreducingnoiseincomputedtomography(CT)images.Intheproposedmethod,denoisingisperformedoneachblockwiththehelpofagivendatabaseofstandardimageblocks.Foreachnoisyblock,itsdenoisedversionisthebestsparsepositivelinearcombinationoftheblocksinthedatabase.Weformulatetheproblemasaconstrainedoptimizationproblemsuchthatthesolutionisthedenoisedblock.Experimentalresultsdemonstratethegoodperformanceoftheproposedmethodovercurrentstate-of-the-artdenoisingmethods,intermsofbothobjectiveandsubjectiveevaluations.

  • 标签: 图像去噪 CT 权重法 计算机断层扫描 约束最优化问题 降低噪声
  • 简介:Tobettersimulatemulti-phaseinteractionsinvolvingfailureevolution,thematerialpointmethod(MPM)hasevolvedforalmosttwentyyears.Recently,aparticle-basedmultiscalesimulationprocedureisbeingdeveloped,withintheframeworkoftheMPM,todescribethedetonationprocessofenergeticnano-compositesfrommoleculartocontinuumlevelsothatamultiscaleequationofstatecouldbeformulated.Inthisletter,amultiscaleMPMisproposedviabothhierarchicalandconcurrentschemestosimulatetheimpactresponsebetweentwomicrorodswithdifferentnanostructures.Preliminaryresultsarepresentedtoillustratethatatransitionregionisnotrequiredbetweendifferentspatialscaleswiththeproposedapproach.

  • 标签: 纳米复合材料 模拟程序 多尺度 MPM 相互作用 物质点法
  • 简介:我们在场为绝缘的弹性体(DE)的一个有限元素方法变换器基于DE的非线性的域理论。方法在商业有限元素软件ABAQUS被实现,它提供一个大图书馆描述有限弹性的功能。这个方法能被用来与复杂配置并且在不同类的变丑下面解决DE变换器的机电的联合问题。

  • 标签: 有限元方法 换能器 弹性体 介电 ABAQUS 有限元软件
  • 简介:Ahigh-density,high-fluxcirculatingfluidizedbed(CFB)riser(100mminIDand10.614minheight)wasappliedinawiderangeofoperatingconditions(withsolidfluxesupto400kg/m2sandsuperficialgasvelocitiesupto12m/s)toexamineitsradialnon-uniformitydynamics.Thesolidsholdupwasdeterminedthroughtheuseofafiber-opticprobeat11axiallevels.Theresultsindicatedthatunderalloperatingconditions,thehighsuperficialgasvelocityandlowsolidfluxesmaintainedalowradialnon-uniformityindex(RNI).Thehigh-density/fluxCFBriserhadseveraluniquecharacteristics,sothatthepeakoftheradialsolidsholdupprofileoccurredatapositionwithr/R=0.8.TheRNIandsolidsholdupatthecross-sectionalpositionhadagoodlogarithmicrelationshipatthelow-densitycondition(withameansolidsholdupof<0.2),andtheRNIdecreasedwhenthemeansolidsholdupexceeded0.2.InvestigationofthedynamicsofstratifiedinjectionrevealedthatthefeedratiohadanimportanteffectonGsandonsolidsholdupdistribution.Anovel"<"shapedaxialsolidsholdupprofilewasfound.Gsdecreasedsharplywhentheup-flowfeedratioexceeded0.5,andRNIwaslowestwhentheup-flowfeedratiowas1.

  • 标签: 气固循环流化床 高密度 高通量 均匀性指标 径向 颗粒浓度分布
  • 简介:鬼力量引起的错误在二种尺寸与平面接口为一个quasicontinuum方法被学习。为一种特殊情况,我们导出错误的分析表情,它被利用证明鬼力量可以为答案的坡度导致一个有限尺寸错误。错误指数地为腐烂离开接口的错误代数学地腐烂离开接口的错误表演的pointwise估计,比onedimensional问题的慢得多,。

  • 标签: 二维平面 连续介质 尺寸误差 指数衰减 解析表达式 点态估计
  • 简介:一个精确、有效的微分照时间元素方法(DQTEM)为解决平常的微分方程(颂诗)被建议,DQTEM的数字驱散和分散比single/multi步的直接集成方法的小得多。当导出时,强加起始的条件的二个方法被给,它避免沉闷起始的条件被强加,并且数字比较显示第一个方法,在哪个起始的排水量和速度的模拟方程被用来直接代替微分照(DQ)颂诗在的模拟方程第一并且分别地,采样削尖的最后比第二个方法更精确,在哪个起始的条件ar的DQ模拟方程相反策划到常规一步一步的直接集成,解决方案根本,采样点能被DQTEM同时获得,并且通常,一个微分照时间元素可能是足够的为自始至终域。广泛的数字比较验证建议方法的效率和精确性。

  • 标签: 结构动力学 微分求积 微分方程式 常微分方程 模拟方程 数值耗散