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14 个结果
  • 简介:Hydrodynamicpropertiesandstructureofstrongshockwavesinclassicaldenseheliumaresimulatedusingnon-equilibriummoleculardynamicsmethods.Theshockspeedinthesimulationreaches100km/sandtheMachnumberisover250,whichareclosetotheparametersofshockwavesintheimplosionprocessofinertialconfinementfusion.Thesimulationsshowthatthehigh-Mach-numbershockwavesindensemediahavenotabledifferencesfromweakshockwavesorthoseindilutegases.Theseresultswillprovideusefulinformationontheimplosionprocess,especiallythestructureofstrongshockwavefront,whichremainsanopenquestioninhydrodynamicsimulations.

  • 标签: shock structure high MACH number DENSE
  • 简介:Fortheissueofdeteriorationindetectionperformancecausedbydynamicallychangingenvironmentinultra-wideband(UWB)multipleinputmultipleoutput(MIMO)radar,thispaperproposesanoveladaptivewaveformdesignwhichisaimedtoimprovetheabilityofdiscriminatingtargetandclutterfromtheradarscene.Firstly,asequenceofMorletwaveletpulseswithfrequencyhoppingandpulsepositionmodulationbyWelch-Costasarrayisdesigned.Thenawaveformoptimizationsolutionisproposedwhichisachievedbyapplyingtheminimizationmutual-information(MI)strategy.Afterthat,withsubsequentiterationsofthealgorithm,simulationresultsdemonstratethattheoptimalwaveformdesignmethodbringsanimprovementinthetargetdetectionabilityinthepresenceofnoiseandclutter.

  • 标签: MORLET小波 波形设计 MIMO 自适应 超宽带 雷达
  • 简介:Purenitrogengaswasheatedwithdirectcurrentarc,atinputpowersfromseveralhundredWtoover5kW,andtheninjectedthroughanozzleintoachamberat1or10Papressure,withthepurposeofacceleratingthegastoveryhighspeedaround7km/s.Variousstructuresofthearcgeneratorandgasexpansionnozzlewereexamined.Resultsshowthatbypassexhaustingoftheboundarylayerbeforeitentersthenozzledivergentsectioncangreatlyincreaseflowspeedofthejet,thusitmightbepossibletousenitrogenasaworkinggasinhighspeedgasdynamictestfacilities.att

  • 标签: 电弧加热 氮气 射流 超高速 低压室 制备
  • 简介:银电影(Ag)和有厚度~的silvergold电影(AgAu)15nm在通过热蒸发的Bk7眼镜上是涂的。在做5.2%的黄金以后,Ag电影的谷物尺寸从13.6把nm归结为9.1nm,也,表面粗糙从1.45nm减少到0.94nm。一盏紫外灯被用作照耀光来源在空气加速腐蚀过程。当AgAu电影更不降级时,在17h以后,照耀,纯银电影表面拐弯黑暗,和发射度从350把nm归结为500nm,几乎微不足道的在紫外放射以后。另外的X光光电子光谱学和原子力量显微图数据被提供显示出电影和他们的表面形态学的原子内容。小谷物尺寸和合金电影的高收拾行李密度在空气与氧阻止银的反应,这被建议,它导致AgAu电影的高稳定性。

  • 标签: 紫外光辐照 超薄银膜 银金合金薄膜 耐久性研究
  • 简介:Thispaperstudiedthespotweldingstructureofultra-highstrengthsteel22MnB5.ANSYSsoftwarewasadoptedtosimulateitsstaticstrength;BS5400algorithmwasusedtocalculatethefatiguelife;andthegroupingmethodwasusedtotestthefatigueperformanceoftensileshearspotweldspecimens.Thesimulationresultswereingoodagreementwiththeexperimentalvalues.Basedonthevalidationofthesimulationmethod,influencesofdifferentstructuralparametersonstaticstrengthandfatiguelifewereexploredbyadoptingsinglefactor.Theresultsshowedthatwithintheselectedstructureparameterrange,increaseofthesheetthickness,nuggetdiameter,sheetwidthandoverlappinglengthcanleadtolongerfatiguelife.Besides,thefatiguelifeofspotweldtookonalinearrelationshipwiththeoverlappinglength,aDoseResprelationshipwiththesheetthickness,andasingleexponentialdecayrelationshipwiththesheetwidthandthenuggetdiameter.Moreover,inordertoestimatetheimpactfromvariousparametersonthefatiguelifeofthespecimens,theTaguchiorthogonaldesignmethodwasappliedinthesimulationdesign.Thesimulatingresultindicatedthatinfluenceofthesheetthicknessonfatiguelifewasthemostsignificant.Inaddition,theeffectsofnuggetdiameter,sheetwidthandoverlappinglengthonfatiguelifewerereducedinturn.

  • 标签: 疲劳寿命 超高强度钢 点焊接头 性能影响 几何参数 ANSYS软件
  • 简介:Theultra-finegrain(UFG)steelisweldedbyusingresistancespotweldingtechniquewithorwithoutrequirementofupsettingforce.Metallographicinspectionshowsthatthegrainsizeofweldnuggetislargerthanthatofthebasemetalandthemicrostructureisalteredsignificantly.Inaddition,contractingdefectssuchasairholescanbefoundinthenuggetcenter.Theexperimentsshowthatthedefectscanbeeffectivelyavoidedbythetechniqueofaddingupsettingforceduringthenuggetcoolingandcrystallizingprocesses.Intensilesheartests,theweldingjointstartstocrackfromtheinneredgeofthecoronabond.Theresultsofmicro-hardnesstestsshowthatthenewlybornmartensitestructuredramaticallyimprovesthehardnessofthejoint.Undertheinteractionsbetweenresidualstressesandregeneratedfinegrains,themicro-hardnessoftheheat-affectedzone(HAZ)islowerthanthatofthenugget,butevidentlyhigherthanthatofthebasemetal.

  • 标签: 焊接过程 电阻点焊 焊缝组织 细化晶粒 金相检验
  • 简介:正如双声道系统有便宜有贵,家庭影院也有各种定位,既有入门的5.1、71声道组合,也有更高规格的沉浸式音效组合(包括全景声和DTS:X)。相比起以前代表高规格的9声道或11声道,

  • 标签: 家庭影院系统 全景 声道 DTS 沉浸式 规格
  • 简介:一新奇、紧缩、高度选择极端宽带(UWB)与一个狭窄的notched乐队一起的通带过滤器被介绍。除了有slotline的基本结构,多重模式的共鸣器(MMR)和微条喂线,这个新奇图案介绍在输入和输出之间的跨coupling喂线提高过滤器选择。设计严格地跟随理论并且验证了由电磁(他们)模拟和实验。另外,狭窄的notched乐队被嵌入一双裂口戒指共鸣器(SRR)以便拒绝可以防碍定义的联邦通讯委员会(FCC)的任何不希望得到的存在无线电信号介绍UWB乐队。由改变SRR的结构的参数,它能容易被调节到任何需要的频率。这个过滤器能集成于UWB通讯系统并且高效地从象无线本地区域网络(WLAN)那样的不希望得到的信号改进干扰免疫。

  • 标签: 超宽带通信系统 带通滤波器 设计 仿真 缺口 谐振腔
  • 简介:Anultra-broadbandandfabrication-tolerantsiliconpolarizationrotatorsplitterisproposedinthisLetter.Benefittingfromthebroadbandandlow-losscharacteristicsofthebi-leveltaperandcounter-taperedcoupler,thedesigneddevicehasasimulatedinsertionlossandcrosstalkoflessthan0.2and-15dBinthewavebandfrom1290to1610nm.Thesecharacteristicsmakeitvaluableinapplicationswithlargebandwidthrequirements,suchasfull-gridCoarsewavelengthdivisionmultiplexer(CWDM)anddiplexer/triplexerfiber-to-the-homesystems.Thefabricationtoleranceofthedesignisalsoanalyzed,showingthatthedeviceperformanceisquitestablewithnormalmanufacturingerrorsinsiliconphotonicsfoundries.

  • 标签: 硅基复合材料 超宽带 设计 偏振 旋转器 制作
  • 简介:Wenumericallydemonstrateanovelultra-broadbandpolarization-independentmetamaterialperfectabsorberinthevisibleandnear-infraredregioninvolvingthephase-changematerialGe2Sb2Te5(GST).Thenovelperfectabsorberschemeconsistsofanarrayofhigh-indexstrong-absorbanceGSTsquareresonatorsseparatedfromacontinuousAusubstratebyalow-indexlosslessdielectriclayer(silica)andahigh-indexGSTplanarcavity.Threeabsorptionpeakswiththemaximalabsorbanceupto99.94%areachieved,owingtotheexcitationofplasmon-likedipolarorquadrupoleresonancesfromthehigh-indexGSTresonatorsandcavityresonancesgeneratedbytheGSTplanarcavity.Theintensitiesandpositionsoftheabsorptionpeaksshowstrongdependenceonstructuralparameters.AheattransfermodelisusedtoinvestigatethetemporalvariationoftemperaturewithintheGSTregion.TheresultsshowthatthetemperatureofamorphousGSTcanreachupto433Kofthephasetransitiontemperaturefromroomtemperatureinjust0.37nswitharelativelylowincidentlightintensityof1.11×108W∕m2,duetotheenhancedultra-broadbandlightabsorbancethroughstrongplasmonresonancesandcavityresonanceintheabsorber.Thestudysuggestsafeasiblemeanstolowerthepowerrequirementsforphotonicdevicesbasedonathermalphasechangeviaengineeringultra-broadbandlightabsorbers.

  • 标签:
  • 简介:孟山都草甘膦除草剂RoundupUltra近日已被巴西批准用于柑橘、甘蔗和咖啡。该产品使用了TransorbII表面活性剂技术,此前已在巴西用于玉米、大豆、棉花和水稻。RoundupUltra是一款粒状高浓度制剂,每公顷的使用量更小,便于储存、运输和处理包装。RoundupUltra的制剂配方确保了产品的快速吸收,并能在阔叶和窄叶内转移。与其他产品相比,其耐雨水冲刷的能力更强。

  • 标签: 草甘膦除草剂 孟山都 巴西 柑橘 咖啡 甘蔗
  • 简介:CeO2稳定了ZrO2极端好nanoparticles成功地经由简单、有效的大音阶的第五音胶化被综合由把zirconylchlorideoctahydrate,铈硝酸盐hexahydrate,和柠檬性的酸用作开始材料的合成途径。一系列技术包括X光检查衍射(XRD),thermogravimetry(TG),微分扫描热量测定(DSC),Fourier变换红外线的光谱学(FTIR),传播电子显微镜学(TEM),和N2-sorption分析,被用来描绘同样准备的样品的结构和形态学。XRD研究显示同样综合的样品具有CeO2的很好使结晶的四角形的阶段有高纯净的稳定的ZrO2。TEM图象证明同样综合的样品与一种平均尺寸由很多好散nanoparticles组成大约10nm。同样综合的四角形的CeO2稳定了ZrO2样品在不同温度被加热以便评估它的热稳定性。exprimental结果表明同样综合的四角形的CeO2稳定了ZrO2样品展览没有阶段转变的出现的优秀稳定性。

  • 标签: 溶胶-凝胶法 合成方法 热稳定性 纳米颗粒 表征 超细
  • 简介:TocharacterizeandidentifymultipleconstituentsinDanhonginjection(DHI),afastultra-highperformanceliquidchromatographycoupledtoelectrosprayionizationquadrupoletime-of-flighttandemmassspectrometry(UHPLC-ESI-QTOF/MS)methodwasestablishedandvalidatedinthepresentstudy.Atotalof63compounds,including33phenolicacids,2C-glycosylquinochalcones,6flavonoidO-glycosides,4iridoidglycosides,6organicacids,5aminoacids,and3nucleosides,wereidentifiedortentativelycharacterized.Inconclusion,theUHPLC-ESI-QTOF/MSmethodisusefulandefficientforin-depthstructuralelucidationofchemicalcompoundsincomplexmatricesofherbalmedicinessuchasDHI.

  • 标签: UHPLC-ESI-QTOF/MS Danhong Injection Radix Salviae Miltiorrhizae Flos Carthami tinctorii TCM Mass spectrometry
  • 简介:Thepresentstudywasdesignedtodevelopandvalidateasensitiveandreliableultrahighperformanceliquidchromatographycoupledwithquadrupoletime-of-flightmassspectrometry(UPLC-QTOF/MS)methodtoseparateandidentifythechemicalconstituentsofQixueShuangbuTincture(QXSBT),aclassictraditionalChinesemedicine(TCM)prescription.UndertheoptimizedUPLCandQTOF/MSconditions,56componentsinQXSBT,includingchalcones,triterpenoids,protopanaxatriol,flavonesandflavanoneswereidentifiedandtentativelycharacterizedwithinarunningtimeof42min.Thecomponentswereidentifiedbycomparingtheretentiontimes,accuratemass,andmassspectrometricfragmentationcharacteristicions,andmatchingempiricalmolecularformulawiththatofthepublishedcompounds.Inconclusion,theestablishedUPLC-QTOF/MSmethodwasreliableforarapididentificationofcomplicatedcomponentsintheTCMprescriptions.

  • 标签: Qixue Shuangbu Tincture UPLC-QTOF/MS Chemical profiling Traditional Chinese medicine