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16 个结果
  • 简介:Concerningthespecificdemandonsolvingthelong-termconjugateheattransfer(CHT)problem,anewalgorithmoftheglobaltightly-coupledtransientheattransferbasedonthequasi-steadyflowfieldisfurtherputforward.Comparedtothetraditionalloosely-coupledalgorithm,thecomputationalefficiencyisfurtherimprovedwiththegreatlyreducedupdatefrequencyoftheflowfield,andmoreovertheupdatestepoftheflowfieldcanbereasonablydeterminedbyusingtheengineeringempiricalformulaoftheNusseltnumberbasedonthechangesoftheinletandoutletboundaryconditions.Takingaductheatedbyinnerforcedairflowheatingprocessasanexample,thecomparingresultstothetightly-coupledtransientcalculationbyFluentsoftwareshowsthatthenewalgorithmcansignificantlyimprovethecomputationalefficiencywithareasonableaccuracyonthetransienttemperaturedistribution,suchasthecomputingtimeisreducedto22.8%and40%whiletheductwalltemperaturedeviationare7%and5%respectivelyusingtwoflowupdatetimestepof100sand50sonthevariableinlet-flowrateconditions.

  • 标签: 耦合算法 共轭传热 紧耦合 瞬态热传导 热传导问题 稳态流动
  • 简介:Accordingto350MWand600MWboilers,underoxygenfuelcondition,throughthereasonablecontroloftheprimaryandsecondaryflowandthecorrectoptionandrevisionofmathematicalmodel,thetemperaturedistribution,heatfluxdistributionandabsorptionheatdistribution,etc.wasobtainedwhichcomparedwiththoseunderaircondition.Throughcalculation,itisobtainedthattheprimaryandsecondaryflowmixedwell,goodtangentiallyfiredcombustioninfurnacewasformed,thetemperatureunderairconditionobviouslyhigherthanthetemperatureunderO26condition.Theadiabaticflametemperatureofwetcyclewasslightlyhigherthanthatofdrycycle.Themaximumheatloadappearedonthewaterwallaroundtheburnerarea.Theheatloadgraduallydecreasedalongthefurnaceheightupanddowninburnerarea.TheheatabsorptioncapacityofthefurnaceunderO26waslowerthanthatundertheaircondition.Theheatabsorptioncapacityoftheplatenheatingsurfaceunder026wasequaltothatunderaircondition.AndtheheatabsorbingcapacityofwaterwallunderO26wasabout7%~12%lessthanthatunderaircondition.

  • 标签: 燃烧锅炉 锅炉燃料 传热特性 氧气 温度分布 绝热火焰温度
  • 简介:Bioluminescenceimagingisakindofemergingdetectiontechnologyatcellular,molecularandgeneticlevel.Themostpopularbioluminescenceimagingmodelisdiffusionapproximation(DA).However,becauseoftheill-posednessoftheDA-basedinverseproblemandtheinstabilityofreconstructionalgorithms,thelocationaccuracyofthereconstructedsourcesislow.Radiativetransferequation(RTE),whichconsidersthedirectionofthephotonmigrationandtheeffectofabsorptionandscatteringintissues,canaccuratelyexpressthetransmissionofbioluminescentphotonsthroughthetissues.Inthispaper,westudiedthebioluminescenceimagingbasedontheRTE.2Dsimulationswereperformed,andquantitativeevaluationwasgivenbytheabsolutesourcepositionerror,therelativesourceareaerrorandtheminimumboundingbox.TheresultsoftheexperimentshowedthattheimagingqualitybasedonRTEwasbetterthanthatonebasedonDA.

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  • 简介:Theeffectsofdifferentrefrigerantsonheattransferperformanceofpulsatingheatpipe(PHP)areinvestigatedexperimentally.Theworkingtemperatureofpulsatingheatpipeiskeptintherangeof20℃-50℃.Thestartuptimeofthepulsatingheatpipewithrefrigerantscanbeshorterthan4min,whenheatingpowerisintherangeof10W-100W.Thestartuptimedecreaseswithheatingpower.ThermalresistancesofPHPwithfillingratio20.55%wereobviouslylargerthanthosewithotherfillingratios.ThermalresistanceofthePHPwithR134aismuchsmallerthanthatwithR404AandR600a.ItindicatesthattheheattransferabilityofR134aisbetter.Inaddition,acorrelationtopredictthermalresistanceofPHPwithrefrigerantswassuggested.

  • 标签: 脉动热管 传热性能 制冷工质 实验 R134A 启动时间
  • 简介:在生物体之发光断层摄影术(BLT)问题,在从光信号的一个小动物内的生物体之发光来源分发在动物身体表面上检测了的一构造份量上。BLT问题是提出病的,经常,Tikhonov规则化被用来获得稳定的近似答案。在常规Tikhonov规则化,选择一个合适的规则化参数平衡近似解决方案的精确性和稳定性是关键的。在这份报纸,一个参数依赖者联合了基于的复杂边界方法(CCBM)Tikhonov规则化被用于放射的转移方程(RTE)管理的BLT问题。由适当地处于知更鸟边界条件调整参数,我们完成一个重要性质:调整答案关于规则化参数是一致地稳定的以便规则化参数能被选择完全基于答案精确性的考虑。分离纵标的有限元素的方法被用来计算数字答案。数字结果被提供说明建议方法的表演。

  • 标签: 生物体之发光 代表性的成像 几何断层摄影术 医药 X 光线照相术 放射的转移 -- 数学模型
  • 简介:Abinaural-loudness-model-basedmethodforevaluatingthespatialdiscriminationthresholdofmagnitudesofhead-relatedtransferfunction(HRTF)isproposed.Astheinputofthebinauralloudnessmodel,theHRTFmagnitudevariationscausedbyspatialpositionvariationswerefirstlycalculatedfromahigh-resolutionHRTFdataset.Then,threeperceptualrelevantparameters,namelyinterauralloudnessleveldifference,binauralloudnesslevelspectra,andtotalbinauralloudnesslevel,werederivedfromthebinauralloudnessmodel.Finally,thespatialdiscriminationthresholdsofHRTFmagnitudewereevaluatedaccordingtojust-noticedifferenceoftheabove-mentionedperceptual-relevantparameters.AseriesofpsychoacousticexperimentswasalsoconductedtoobtainthespatialdiscriminationthresholdofHRTFmagnitudes.Resultsindicatethatthethresholdderivedfromtheproposedbinaural-loudness-modelbasedmethodisconsistentwiththatobtainedfromthetraditionalpsychoacousticexperiment,validatingtheeffectivenessoftheproposedmethod.

  • 标签: 阈值分析 空间分辨 传递函数 头相关传输函数 HRTF 模型评价
  • 简介:Inthispaper,wepresentathreedimensionalnumericalinvestigationofheattransferinaparabolictroughcollectorreceiverwithlongitudinalfinsusingdifferentkindsofnanofluid,withanoperationaltemperatureof573Kandnanoparticleconcentrationof1%involume.Theoutersurfaceoftheabsorberreceivesanon-uniformheatflux,whichisobtainedbyusingtheMonteCarloraytracingtechnique.Thenumericalresultsarecontrastedwithempiricalresultsavailableintheopenliterature.AsignificantimprovementofheattransferisderivedwhentheReynoldsnumbervariesintherange2.57×104≤Re≤2.57×105,thetube-sideNusseltnumberincreasesfrom1.3to1.8times,alsothemetallicnanoparticlesimproveheattransfergreatlythanothernanoparticles,combiningbothmechanismsprovidesbetterheattransferandhigherthermo-hydraulicperformance.

  • 标签: 强化传热 纵向翅片 接收器 抛物 太阳能 金属纳米粒子
  • 简介:轧了nanorods用诱导地联合的血浆与Ninano岛面具蚀刻被制作。poly[2-methoxy-5-(2乙醇)hexoxy-1,4-phenylenevinylene](MEH-PPV)/GaN-nanorod混血儿结构被扔MEH-PPV电影在上制作由使用纺纱涂层过程轧了nanorods。在混合结构,空间分离被最小化完成高效率的非放射的反响的精力转移。由MEH-PPV/GaN-nanorod混合结构组成的一台新奇设备的光性质被分析光致发光(PL)学习系列。与相比纯轧了nanorods,乐队边排放的PL紧张在MEH-PPV/GaN-nanorods轧了像黄乐队的三次,和紧张稍微被压制一样,被提高。获得的结果被精力转移在之间分析轧了nanorods和MEH-PPV。一个精力转移模型被建议解释现象。

  • 标签: 混合氮化物/有机半导体 纳米结构 能量转移 的带边发射改进
  • 简介:Inthepresentwork,theheattransferstudyfocusesonassessmentoftheimpactofbedtemperatureonthelocalheattransfercharacteristicbetweenafluidizedbedandverticalrifledtubes(38mm-O.D.)inacommercialcirculatingfluidizedbed(CFB)boiler.Heattransferbehaviorina1296t/hsupercriticalCFBfurnacehasbeenanalyzedforGeldartBparticlewithSautermeandiameterof0.219and0.246mm.TheheattransferexperimentswereconductedfortheactiveheattransfersurfaceintheformofmembranetubewithalongitudinalfinatthetubecrestunderthenormaloperatingconditionsofCFBboiler.AheattransferanalysisofCFBboilerwithdetailedconsiderationofthebed-to-wallheattransfercoefficientandthecontributionofheattransfermechanismsinsidefurnacechamberwereinvestigatedusingmechanisticheattransfermodelbasedonclusterrenewalapproach.ThepredictedvaluesofheattransfercoefficientarecomparedwithempiricalcorrelationforCFBunitsinlarge-scale.

  • 标签: 循环流化床(CFB)锅炉 传热特性 垂直 床温 循环流化床锅炉 纵向翅片管
  • 简介:Asystemofjointlytransferringtimesignalswitharateof1pulsepersecond(PPS)andfrequencysignalsof10MHzviaadensewavelengthdivisionmultiplex-based(DWDM)fiberisdemonstratedinthispaper.Thenoisesofthefiberlinksaresuppressedandcompensatedforbyacontrolledfiberdelayline.Amethodofcalibratingandcharacterizingtimeisdescribed.The1PPSissynchronizedbyfeed-forwardcalibratingthefiberdelaysprecisely.Thesystemisexperimentallyexaminedviaa110kmspooledfiberinlaboratory.Thefrequencystabilitiesoftheuserendwithcompensationare1.8×10-14at1sand2.0×10-17at104saveragetime.Thecalculateduncertaintyoftimesynchronizationis13.1ps,whereasthedirectmeasurementoftheuncertaintyis12ps.Next,thefrequencyand1PPSaretransferredviaametropolitanareaopticalfibernetworkfromonecentralsitetotworemotesiteswithdistancesof14kmand110km.Thefrequencystabilitiesof14kmlinkreach3.0×10-14averagedin1sand1.4×10-17in104srespectively;andthestabilitiesof110kmlinkare8.3×10-14and1.7×10-17,respectively.Theaccuraciesofsynchronizationareestimatedtobe12.3psforthe14kmlinkand13.1psforthe110kmlink,respectively.

  • 标签: 时间同步 频率信号 传输时间 光纤网络 频率稳定性 光纤延迟线
  • 简介:Inthispaper,weconsiderthemulti-dimensionalasymptoticpreservingunifiedgaskineticschemeforgrayradiativetransferequationsondistortedquadrilateralmeshes.Differentfromtheformerscheme[J.Comput.Phys.285(2015),265-279]onuniformmeshes,inthispaper,inordertoobtaintheboundaryfluxesbasedontheframeworkofunifiedgaskineticscheme(UGKS),weusetherealmulti-dimensionalreconstructionfortheinitialdataandthemacro-termsintheequationofthegraytransferequations.Wecanprovethattheschemeisasymptoticpreserving,andespeciallyforthedistortedquadrilateralmeshes,anine-pointscheme[SIAMJ.SCI.COMPUT.30(2008),1341-1361]forthediffusionlimitequationsisobtained,whichisnaturallyreducedtostandardfive-pointschemefortheorthogonalmeshes.Thenumericalexamplesondistortedmeshesareincludedtovalidatethecurrentapproach.

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  • 简介:Thevariationinarccharacteristicsandbehaviorofmetaltransferwiththechangeinpulseparametershasbeenstudiedbyhighspeedvideocameraduringpulsecurrentflux-coredarcwelddeposition.Acomparativestudyofsimilarnaturehasalsobeencarriedoutduringflux-coredarcwelddepositioninglobularandspraytransfermodes.Theeffectofpulseparametershasbeenstudiedbyconsideringtheirmeancurrentandarcvoltage.Thearccharacteristicsstudiedbyitsrootdiameter,projecteddiameterandlength,andthebehaviorofmetaltransfernotedbythemetaltransfermodelandthedropletdiameterhavebeenfoundtovarysignificantlywiththepulseparameters.TheobservationmayhelpinunderstandingthearccharacteristicswithrespecttothevariationinpulseparameterswhichmaybebeneficialinusingpulsecurrentFCAWtoproducedesiredweldquality.

  • 标签: 电弧特性 行为研究 脉冲电流 电弧焊接 金属 低碳钢
  • 简介:电影动量和在加速上的薄有限幂定律液体的热运输特征上的内部加热来源的效果不稳定的水平拉长的接口被学习。不同于这块地里的很古典的工作,为改变热电导率的液体电影和概括Fouriers法律的一般表面温度分布被考虑。适当类似转变被用来与一组二点的平常的微分方程(颂诗)把强烈非线性的管理部分微分方程(PDE)变换成一个边界价值问题。在液体电影厚度和摇摆参数之间的通讯在MATLAB用BVP4C节目被导出。自我类似颂诗的数字答案用与一个Runge-Kutta重复程序和牛顿计划相结合的射击技术被获得。液体上的深奥物理参数的效果水平速度和温度分发被介绍并且讨论。

  • 标签: 非牛顿的液体 非线性的方程 薄电影 加热转移 内部加热 拉长表
  • 简介:Cr的Nanopowder:Cr的GGG和nanopowder,Nd:有从0.1at.%到1.5at.%的Cr3+的不同集中的GGG被大音阶的第五音胶化方法用醋酸和乙烯乙二醇综合。热gravimetric分析和微分扫描热量测定(TGA-DSC),X光检查衍射(XRD)和光致发光光谱学被用来描绘粉末。当在1000点对待时,雏晶尺寸是大约58nm?????????????????猯灵?匠?猼'T资???猼灵?????????猯'T??猼灵???? ̄?????猯'T????猯灵??猼'T?????吗????????????????‵渠????????浮??

  • 标签: NANOPOWDER Cr, Nd : GGG 大音阶的第五音胶化 荧光一生 精力转移效率 稀土元素