简介：Westudythegeneralrepresentationsofpositivepartialtranspose(PPT)statesinCKCMCN.ForthePPTstateswithrank-Nacanonicalformisobtained,fromwhichasufficientseparabilityconditionispresented.

简介：通过理论分析和PIC数值模拟,研究了阳极腔区结构对无箔二极管I-Ⅴ特性的影响,得到了束流强度和结构影响因子的变化规律.研究发现,当阴阳极间距大于0时,无箔二极管的结构影响因子随着阳极腔区半径的增大而减小并逐渐趋于稳定,且对于较小的阴极外半径、较大的漂移管半径、较大的阴阳极间距,达到稳定后的结构影响因子越小,并给出了结构影响因子的可调节范围.在TPG700脉冲驱动源上开展了初步实验研究,对实验中的回流电子束进行数值模拟分析并去除其影响以后,实验结果很好地符合了理论分析结论.

简介：研究了不同风速下激光辐照C/C复合材料的氧化速率,利用温度场计算结果,结合氧气在空气中的传质速率,计算了激光辐照下C/C复合材料氧化放热.结果表明,在亚音速的风速下,氧化对C/C复合材料烧蚀的贡献很小,因此,作为激光防护材料,可以忽略C/C复合材料在激光辐照期间的氧化烧蚀.

简介：

简介：Anenvironmentallyfriendlyprecursor,adenosine,hasbeenusedasadualsourceofCandNtosynthesizenitrogen-dopedcarboncatalystwith/withoutFe.Ahydrothermalcarbonizationmethodhasbeenusedandwateristhecarbonizationmedia.Themorphologyofsampleswith/withoutFecomponenthasbeencomparedbyHRTEM,andtheresultshowsthatFecanpromotethegraphitizationofcarbon.Furtherelectro-chemicaltestshowsthattheoxygenreductionreaction(ORR)catalyticactivityofFe-containingsample(C–FeN)ismuchhigherthanthatoftheFe-freesample(C–N).Additionally,theintermediatesofC–FeNformedduringeachsyntheticprocedurehavebeenthoroughlycharacterizedbymultiplemethods,andthefunctionofeachprocedurehasbeendiscussed.TheC–FeNsampleexhibitshighelectro-catalyticstabilityandsuperiorelectro-catalyticactivitytowardORRinalkalinemedia,withitshalf-wavepotential20mVlowerthanthatofcommercialPt/C(40wt%).Itisfurtherincorporatedintoalkalinepolymerelectrolytefuelcell(APEFC)asthecathodematerialandledtoapowerdensityof100mW/cm~2.

简介：应用标量光场光强的传统定义,推导了具有轴对称性的傍轴标量光束的光强二阶矩的传输规律。在此基础上,给出了光束的束腰半径、远场发散角及光束质量因子M2,并证明了光束质量因子M21。应用标量光场光强的精确定义,计算了非傍轴标量高斯光束的质量因子,结果表明:当ω0λ时,光束质量因子M2可以小于1,并随光束的束腰半径趋于零而趋向于零;ω0>λ时,高斯光束的质量因子M2非常接近于1,且随光束束腰半径的增大迅速趋向于1。此外,文章还对一些相关的问题进行了讨论。

简介：Variousagriculturalcropresiduesincludingcornstover,corncob,andsorghumstalkwithamoisturecontentof75wt%weresubjectedtoalongpretreatment(12-60h)withsupercriticalCO2(scCO2),atlowtemperature(50-80℃)andapressureof17.5-25.0Mpa.Thesugaryieldsfromtheenzymatichydrolysis(EH)ofthepretreatedsampleswereasmuchasthree-tofourfoldgreaterthanthoseaffordedbytherawmaterials.However,whenpretreatmentwasconductedwithinashorttime(e.g.0.5h),aspreviouslyreportedintheliterature,onlyaslightincreaseintheEHsugaryieldswasobserved.TheproposedscCO2pretreatmentmechanismdemonstratedtheroleofmoistureinthesystem.Wetting,softening,andswellingwereobservedtomainlyaffectthelignocellulosewhenasuitableamountofwaterwasadded.Finally,thesampleswereanalysedbyX-raydiffractionandscanningelectronmicroscopy,beforeandafterpretreatment,toinvestigatethechangesinthemicroscopicstructureofthebiomass.

简介：分子的动态模拟被执行在交流上调查事件精力的效果:从C和H的H电影生长原子流动。我们的模拟证明在低事件精力(1eV)的电影生长被H和C原子的吸附统治。在中等事件精力(10和20eV)，有在表面吸附的H原子的事件H原子的抽象反应变得重要。在高事件精力(30和40eV)，交流:H电影生长是一个二拍子的圆舞过程：一个人是吸附和C原子的浅培植，并且其它是H原子的深培植。[从作者抽象]

简介：Anovelgas-phaseelectrocatalyticcellcontainingalow-temperatureprotonexchangemembrane(PEM)wasdevelopedtoelectrochemicallyconvertCO2intoorganiccompounds.TwodifferentCu-basedcathodecatalysts(CuandCu-C)werepreparedbyphysicalvapordepositionmethod(sputtering)andsubsequentlyemployedforthegas-phaseelectroreductionofCO2atdifferenttemperatures(70-90℃).ThepreparedelectrodesCuandCu-CwerecharacterizedbyX-raydiffraction(XRD),X-rayphotoemissionspectroscopy(XPS)andscanningelectronmicroscopy(SEM).Asrevealed,CuispartiallyoxidizedonthesurfaceofthesamplesandtheCuandCu-Ccathodiccatalystswerecomprisedofaporous,continuous,andhomogeneousfilmwithnanocrystallineCuwithagrainsizeof16and8nm,respectively.Theinfluenceoftheappliedcurrentandtemperatureontheelectro-catalyticactivityandselectivityofthesematerialswasinvestigated.Amongthetwoinvestigatedelectrodes,thepureCucatalystfilmshowedthehighestCO2specificelectrocatalyticreductionratesandhigherselectivitytomethanolformationcomparedtotheCu-Celectrode,whichwasattributedtothehigherparticlesizeoftheformerandlowerCuO/Curatio.Theobtainedresultsshowpotentialinterestforthepossibleuseofelectrical「enewableenergyforthetransformationofCO2intovaluableproductsusinglowmetalloadingCubasedelectrodes(0.5mgCucm2)preparedbysputtering.

简介：用多光子光电效应理论简要分析了多光子光电效应实验,指出多光子光电效应满足nhν=12mv20+φ(hν0)且nν/ν0=4/3。同时用微扰法及单光子光电效应理论分析了H原子电离问题,结果表明也是当ω/ω0=4/3时电离几率最大

简介：自然数集按（mod6）排列后，将自然数符号螺旋对称分布的规律与自然律有机关联起来研究，从中发现数集中部分合数M中所包含相同素因子P，q周期分布与等距传递的规律，即双重素数P,q实项、虚项原构、同构同因子对应组螺旋对称分布结构的形式与规律，可模拟宇宙万物的时空螺旋运动状态，模拟DNA双螺旋结构碱基（A、T、G、C）序列遗传密码结构与形式。亦可作为一种创新方法开发应用研究，为研究DNA序列结构的数学编码，研究宏观宇宙、中观生物、微观质量的对应螺旋运动状态，预测宇宙万物相互关联相互作用的变化规律与趋势，构建基于宇宙中空时序的自然数双重素数因子对应组（多组）螺旋延伸的数码模型，高度抽象探讨与理解宇宙万物运动变化的原本规律，为相关问题的表述与解决提供数码螺旋的解决方案。

简介：Carbon-supportedPdnanoparticleswerepreparedbymicrowaveheating-glycolreductionmethod,andcharacterizedbyawidearrayofexperimentaltechniquesincludingX-raydiffractionspectroscopy(XRD)andtransmissionelectronmicroscopy(TEM).TheelectrooxidationbehaviorsofethanolonthePd/Celectrodeinalkalinemediawereinvestigatedusingcyclicvoltammetry(CV),chronoamperometry(CA),electrochemicalimpedancespectroscopy(EIS)andsinglecellperformancemethods.Pd/Celectrodeforethanoloxidationshowedhighelectro-catalyticactivityandlongtermstability.However,itisobservedthatthecurrentdensitydecreaseswiththeincreasingofthepotentialandnegativeimpedancepresentsinthepotentialfrom-0.1to0.1V.Thedecreasingcurrentdensityandthenegativeimpedancecouldbeduetotheadsorbedintermediatesspeciesthatinhibitedthefurtheroxidationofethanol.BasedonthechemicalreactionanalysisandEISspectra,equivalentcircuitsrelatingtovariouspotentialzoneshavebeenobtained.TheseresultsrevealthedynamicadsorptionofintermediatesspeciesonPdsurfaces.Significantly,itisclarifiedthattheadsorptionbehaviorbeginsfromthemaximumcatalysisofelectro-catalysisandendsintheformationofthepalladium(II)oxidelayerontheelectrodesurface.

简介：TheCprogramminglanguageisexpressiveandflexible,butnotsafe;asitsexpressivepowerandflexibilityareobtainedthroughunsafelanguagefeatures,andimproperuseofthesefeaturescanleadtoprogrambugswhosecausesarehardtoidentify.SinceCiswidelyused,anditisimpracticaltorewriteallexistingCprogramsinsafelanguages,sowaysmustbefoundtomakeCprogramssafe.ThispaperdealswiththeunsafefeaturesofCandpresentsasurveyonexistingsolutionstomakeCprogramssafe.Wehavestudiedbinary-levelinstrumentationtools,sourcecheckers,source-levelinstrumentationtoolsandsafedialectsofC,andpresentacomparisonofdifferentsolutions,summarizedthestrengthsandweaknessesofdifferentclassesofsolutions,andshowmeasuresthatcouldpossiblyimprovetheaccuracyoralleviatetheoverheadofexistingsolutions.

简介：

简介：ThefirststarsintheearlyUniversewereformedabout400millionyearsafterthebigbang.VerificationoftheexistenceofthesestarsisimportantforourunderstandingoftheevolutionoftheUniverse[1].IthasbeenpredictedthatforPopulation-IIIstellarproductionyields,theabundancesofodd-Zelementsareremarkablydeficientcomparedtotheiradjacenteven-Zelements[2].Astronomersaresearchingforlong-lived,lowmassstarswiththeuniquenucleosyntheticpatternmatchingthepredictedyields[3].

简介：证明了在场强为零势不为零的复连通区域,规范势沿粒子运动闭合路径的不可积积分是Berry几何相位。说明了由规范势构成的不可积相位因子中一部分是几何Berry相因子,并以电磁场为例说明规范场和相位因子的关系。因此不可积Berry相因子最完整地描述了与规范场有关的物理现象

简介：

简介：当用于含能材料的表面涂层时，ParyleneC涂层优良的电绝缘性能，使得涂层后的炸药表面容易产生静电积累，因此可能会降低炸药的静电安全性。通过试验初步考核了ParyleneC涂层后炸药的静电摩擦感度，并与未涂层炸药以及带聚氨酯复合涂层的炸药进行对比。实验简易装置如图1所示。

简介：The12C+13Csystemhasbeenstudiedextensively,becauseofthesimilarityoftheentrancechanneltotheastrophysicallyimportant12C+12Creaction[1??3].Untilnow,threedifferentmethodshavebeenexploitedtoperformthefusioncrosssectionmeasurementsfor12C+13CundertheCoulombbarrier:(1)measuringtheyieldofcharacteristicrays,(2)thetotal-rayyieldsusingNaIsummingdetectorsand(3)theactivityofthereactionresidue24Na(T1=2=15.0h).Recently,thefusioncrosssectionof12C+13Chasbeenmeasureddownto0.9nbthroughtheactivitymeasurementbyourgroup[4].Althoughthestatisticalmodelcalculationsinallthesethreemethodshavebeenroutinelyusedtoconverttheobservedpartialcrosssectionsintothetotalfusioncrosssections[5],thesystematicuncertaintyinducedbythestatisticalcorrectionshasnotbeenstudiedverywell.

简介：采用以离子数比为控制变量的对数函数控制器,研究了不同填充因子下调谐衰减因子对强流离子加速器中初始分布为K-V分布的离子束束晕-混沌控制的影响。研究表明,使用对数函数控制器时,较大的调谐衰减因子下,可以控制束晕-混沌的填充因子取值范围较大,且填充因子越大控制效果越好;较小的调谐衰减因子对束晕-混沌的控制效果影响相对较大。