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

简介：通过在谐振腔内插入窄带滤光片,开展了XeF（C-A）蓝绿激光窄线宽输出实验研究。研究结果表明,采用该方法,可以获得焦耳量级能量、线宽小于2nm、波长稳定的激光输出,激光最窄线宽为1.3nm。增大滤光片与谐振腔光轴的入射角,激光器输出能量降低。

简介：径向三腔预调制型同轴虚阴极振荡器的三腔调制腔结构由3个半开放式同轴谐振腔构成,能起到显著的束流调制作用,从而提高了电子束与微波场的耦合效率。数值模拟结果表明：改变调制腔长度可对系统工作频率进行调谐,其效率为3dB时的调谐带宽约为400MHz。经过优化设计,在二极管输入电压约为600kV,发射电流约为60kA的条件下,获得了平均功率约为7.2GW,工作频率为2.67GHz的微波输出,束波转换效率达到20%。

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：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：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：精密垫片零件，如图1所示，零件材料为1Cr18Ni9Ti，强度大（σb=650MPa），有一定塑性。从零件尺寸精度看，φ4mm外圆为IT7级精度，φ4mm外圆与φ2mm内孔有很高的同轴度要求，冲裁断面与零件两端面有垂直度要求，普通冲压不能达到零件精度：从工序的角度看，有冲孔和落料工序，剪切面粗糙度Ra≤3．2μm，属于光洁冲裁范畴；另外，技术条件中要求零件两大面不得有任何划伤，且光滑平整。总体上看，该零件的冲压加工性不好，难度较大，对模具的设计、选材、制造要求都较高。

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：

简介：

简介：药柱传统的手动A型扫描探伤方法存在，检测过程的稳定性以及检测结果的准确性、可靠性较低，检测结果不够直观等不足之处。为了解决这些问题，对超声C-扫描成像检测技术的系统条件、技术参数、缺陷大小的系统标定等开展了研究，确定了炸药柱水浸式超声C-扫描成像检测条件，并对利用手动A型超探仪探伤有缺陷（包括分层类和疏松）的PBX-9003和TNT药柱进行了C-扫描成像检测。