简介:Open-loopflowcontrolmethodwasusedtoaffectthedevelopmentofaturbulentwakebehindaD-shapedbluffbody.Loudspeakerswereembeddedinsidethebluffbodytoproducetwozero-net-massfluxjetsthrough2mm-widespan-wiseslotslocatedalongtheupperandloweredgesontherearwall.Thedragforcesfordifferentactuationamplitudes(C_μtheratiobetweenthemomentumoftheactuatingjetsandthemomentdeficitcausedbythebluffbody)andfrequencies(Sr_A)wereexamined.Theeffectsofthephasedifferenceinthetwojets(0andπ)werealsostudied.ItwasfoundthatwhenC_μwas0.1%,adragreductionupto5%wasachievedwhenthevelocitiesofthetwojetsvariedinphaseatafrequencyofSt_A=0.16.Whenthevelocitiesofthetwojetsvariedrroutofphase,significantdragincreasewasobserved.
简介:AbstractFortheweaklyinhomogeneousacousticmediuminΩ={(x,y,z):z>0},weconsidertheinverseproblemofdeterminingthedensityfunctionρ(x,y).Theinversioninputforourinverseproblemisthewavefieldgivenonaline.Wegetanintegralequationforthe2-Ddensityperturbationfromthelinearization.Byvirtueoftheintegraltransform,weprovetheuniquenessandtheinstabilityofthesolutiontotheintegralequation.Thedegreeofill-posednessforthisproblemisalsogiven.
简介:M.Randic首先引入了Wiener.Hosoya指标,该指标可用于对分子的结构,性质和活跃性等方面进行研究.有且仅有一个顶点的度大于或等于3的树称为spider.本文对直径为d,且具有最大Wiener-Hosoya指标的spider进行了刻划.
简介:Basedonconsolidationequationsproposedforunsaturatedsoil,ananalyticalsolutionfor1Dconsolidationofanunsaturatedsingle-layersoilwithnonhomogeneousmixedboundaryconditionisdeveloped.Themixedboundaryconditioncanbeusedforspecialapplications,suchastestsoccurinlaboratory.Theanalyticalsolutionisobtainedbyassumingallmaterialparametersremainconstantduringconsolidation.Inthederivationoftheanalyticalsolution,thenonhomogeneousboundaryconditionisfirsttransformedintoahomogeneousboundarycondition.Then,theeigenfunctionandeigenvaluearederivedaccordingtotheconsolidationequationsandthenewboundarycondition.Finally,usingthemethodofundeterminedcoefficientsandtheorthogonalrelationoftheeigenfunction,theanalyticalsolutionforthenewboundaryconditionisobtained.Thepresentmethodisapplicabletovarioustypesofboundaryconditions.Severalnumericalexamplesareprovidedtoinvestigatetheconsolidationbehaviorofanunsaturatedsingle-layersoilwithmixedboundarycondition.
简介:Inthispaper,ahigh-orderfinite-volumeschemeispresentedfortheone-dimensionalscalarandinviscidEulerconservationlaws.TheSimpson’squadratureruleisusedtoachievehigh-orderaccuracyintime.TogetthepointvalueoftheSimpson’squadrature,thecharacteristictheoryisusedtoobtainthepositionsofthegridpointsateachsub-timestagealongthecharacteristiccurves,andthethird-orderandfifth-ordercentralweightedessentiallynon-oscillatory(CWENO)reconstructionisadoptedtoestimatethecellpointvalues.Severalstandardone-dimensionalexamplesareusedtoverifythehigh-orderaccuracy,convergenceandcapabilityofcapturingshock.
简介:用Co2(CO)8与CH3CSNH2反应制得产物Ⅰ,又用Na2Fe(CO)4与Ⅰ反应制得产物Ⅱ(Ⅰ:Co3(μ3-S)(CO)7(CH3CSNH),Ⅱ:Co2Fe(μ3-S)(CO)7(CH3CSNH).通过元素分析。IR、UV、1HNMR、MS表征并用X射线衍射法测得Ⅱ的单晶结构.该簇合物属三斜晶系、PT空间群,晶胞参数:a=0.9203(1),b=1.1296(2),c=1.1425(2)nm;α=116.40°(2),β=101.92°(2),γ=92.58°(1);z=2,V=1.2162nm3,Dc=1.698cm3,μ=21.89cm-1.结构分析表明,Co2FeS构三角锥分子骨架,所有CO均为端基配体,S1为面桥基配体,CH3CSNH为双齿配体,与Co、Fe形成五元环结构.
简介:采用直接动力学的方法,对多通道反应体系Br+CH3S(O)CH3进行了理论研究.在BH&H-LYP/6-311G(2d,2p)水平下获得了优化几何构型、频率及最小能量路径(MEP),能量信息的进一步确认在MC-QCISD(单点)水平下完成.利用正则变分过渡态理论,结合小曲率隧道效应校正(CVT/SCT)方法计算了该反应的两个可行的反应通道在200K~2000K温度范围内的速率常数.在整个反应区间内,生成HBr的反应通道与生成CHa的反应通道存在着竞争,前者是主反应通道,后者是次反应通道.变分效应和小曲率隧道效应对反应速率常数的计算影响都很小.理论计算得到的两个反应通道的反应速率常数与实验值符合得很好.
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简介:BSTOdielectricceramicwaspreparedfromSrTiO3andBaTiO3powderssynthesizedbyhydrothermalmethod,aswellasfromBa0.6Sr0.4TiO3powdersynthesizedbyconventionalsolid-statereaction.Theformercanbesinteredatarelativelylowtemperatureof1120℃.CharacterizationbySEMshowedthatthegrainshapesofbothceramicsarecubical,thoughthegrainsizeoftheformerismuchsmaller.Dielectricconstantsmeasuredat20℃wereshowntovarywithfrequencyintherangefrom1kHzto2MHzanddcbiasfield,andfurtherthatthedielectriclossoftheformertobelessthan2×10-3inthefrequencyrangeof20kHzto1MHz,muchsmallerthanthatofthelattersample.Fortheformer,temperaturedependenceofdielectricconstantismuchflatterandthereexistsanextendedphasetransitiondiffusioncoveringawidetemperaturerangeofCurietemperatureTc.Thesmallergrainsizeoftheformerdepressesthedcbiaselectricalfielddependenceofdielectricconstant.Thetunabilityis7%underabiasfieldof0.6kV/mmdc.
简介:Temperature-dependentphotoluminescencecharacteristicsoforganic-inorganichalideperovskiteCH3NH3PbI3-xClxfilmspreparedusingatwo-stepmethodonZnO/FTOsubstrateswereinvestigated.Surfacemorphologyandabsorptioncharacteristicsofthefilmswerealsostudied.Scanningelectronmicroscopyrevealedlargecrystalsandsubstratecoverage.Theorthorhombic-to-tetragonalphasetransitiontemperaturewas140K.Thefilms’excitonbindingenergywas77.6±10.9meVandtheenergyofopticalphononswas38.8±2.5meV.TheseresultssuggestthatperovskiteCH3NH3PbI3-xClxfilmshaveexcellentoptoelectroniccharacteristicswhichfurthersuggeststheirpotentialusageinperovskitebasedoptoelectronicdevices.
简介:TwopossiblereactionmechanismsofVS~+(~3∑~-,~1Γ)withCOinthegasphasehavebeenstudiedbyusingB3LYP/TZVPandCCSD(T)/6-311+G(3dr,3pd)methods:theO/Sexchangereaction(VS~++CO→VO~++CS)andtheS-transferreaction(VS~++CO→V~++COS).Thetworeactionsproceedviatwo-stepandone-stepmechanism,respectively.ThebarriersofthetripletandsingletPESsare30.6and50.9kcal/mol,respectively,forO/Sexchangereactionand7.3and50.2kcal/mol,respectively,fortheS-transferreaction.Theresultsindicatethatthetripletgroundstatereactionismorefavorable,andtheS-transferreactionismorefavorablethantheO/Sexchangereaction,whichisingoodagreementwiththeexperimentalobservation.
简介:Inthisnotesomerecurrencerelationsforthedimensionsofthesplinespacesonsocalled0-starsarepresented.
简介:Generally,ROSareregardedashostdefensemoleculesthatarereleasedbyneutrophilstodestroyexogenouspathogenssuchasbacteriaandtoactassecondarymessengersinsignaltransduction.However,increasedproductionofROSisalsoinvolvedininducingpathophysiologicalchangessuchasapoptosis,cellcycledisruption,andnecrosis.Forthisreason,inductionofROS-mediateddamageincancercellsbypharmacologicalagentsthateitherpromoteROSgenerationordisablethecellularantioxidantsystemisconsideredapotentialtherapeuticstrategyforpreferentiallykillingcancercells[1].