简介：为了分析电流型CdZnTe（CZT）探测器的脉冲线性,利用CZT探测器测量得到了脉冲宽度为50ns的脉冲X射线响应曲线,采用波形时间积分法分析了其线性特性。结果表明,以波形时间积分为测量目标量,当X射线照射量在0.160-0.826mR范围时,在10%的不确定度范围内,样品探测器可作为线性测量系统的探测器件;以幅值为测量目标量,工作电压为400V时,在5%的不确定度范围内,样品探测器可作为线性测量系统的探测器件。

简介：采用直流X射线连续能谱照射晶体,以极小的步进角,测量一定角度范围内,不同入射角度下的衍射能谱,通过提取各个角度衍射能谱中同一能量X射线的衍射强度,微分得到该能量的平晶摇摆曲线。与传统测量方法相比,该方法具有更大的X射线能量测量范围,可通过一次角度扫描,同时给出多个能量的摇摆曲线。利用该方法开展了16~21keV区间内LiF（200）平晶摇摆曲线的相对强度标定,结果表明,晶体摇摆曲线的半高宽随X射线能量增加而缓慢减小,而峰值强度随X射线能量增加则缓慢增加,在入射能谱强度变化较大区间内,该方法测量结果的不确定度较大。

简介：为了分析评价航空发动机燃烧状态，采用拉曼散射技术在线测量了航空涡轮发动机燃烧流场主要组分。基于发动机实验现场条件，建立了用于发动机燃烧场主要组分测量的拉曼散射实验系统，测量了发动机试验过程中流场主要组分的拉曼光谱；通过光谱计算获得了流场主要组分含量信息。实验结果表明：采用自发拉曼散射技术可以较好地完成航空涡轮发动机燃烧场主要组分摩尔分数的测量工作。

简介：目的:开口圆柱壳作为板壳组合结构的组成部分被广泛应用于工程实践中。本文探讨开口圆柱壳结构参数(长度、半径、厚度和夹角等)和边界条件对其振动特性的影响,这对工程结构的减振设计具有重要意义。通过推导开口圆柱壳的解析解及其求解过程,建立加筋开口圆柱壳和板-壳耦合模型振动分析的理论基础。创新点:1.推导行波与驻波结合形式的解析解;2.建立回传射线矩阵法分析开口圆柱壳结构振动的流程;3.分析得到大模态数下开口圆柱壳固有频率随壳厚线性变化;直边简支时,曲边边界条件对固有频率影响不大。方法:1.基于Donnell-Mushtari-Vlasov(DMV)薄壳理论,推导两对边简支的开口圆柱壳行波与驻波结合形式的解析解;2.基于回传射线矩阵法原理,推导出开口圆柱壳的固有频率方程;3.采用黄金分割法求解开口圆柱壳的固有频率方程,得到精确的固有频率;4.分析开口圆柱壳不同结构参数和边界条件对固有频率的影响。结论:1.回传射线矩阵法适用于开口圆柱壳的振动分析且具有很高的精度;2.开口圆柱壳的固有频率随其长度的增加而减小;3.对于绝大部分模态数,开口圆柱壳的固有频率随其半径的增加而减小;4.开口圆柱壳的固有频率随壳厚的增加而增加,当周向模态数n=1和2时,不同壳厚的开口圆柱壳固有频率相差很小,当周向模态数n≥7时,开口圆柱壳的固有频率随壳厚线性变化;5.对于绝大多数模态数,开口圆柱壳的固有频率随夹角的增大而快速减小;6.对于两曲边简支的开口圆柱壳,其固有频率从高到低对应两直边的边界条件为固支、简支和自由;7.对于两直边简支的开口圆柱壳,两曲边的边界条件对其固有频率的影响不大。

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简介：Wehavedevelopedanewradiographysetupwithashort-pulselaser-drivenx-raysource.Usingaradiographyaxisperpendiculartobothlong-andshort-pulselasersallowedoptimizingtheincidentangleoftheshort-pulselaseronthex-raysourcetarget.Thesetuphasbeentestedwithvariousx-raysourcetargetmaterialsanddifferentlaserwavelengths.Signaltonoiseratiosarepresentedaswellasachievedspatialresolutions.ThehighqualityofourtechniqueisillustratedonaplasmaflowradiographobtainedduringalaboratoryastrophysicsexperimentonPOLARs.

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简介：Inthisarticle,wetaketheX(5568)asthediquark-antidiquarktypetetraquarkstatewiththespin-parityJ~P=0~+,constructthescalar-diquark-scalar-antidiquarktypecurrent,carryouttheoperatorproductexpansionuptothevacuumcondensatesofdimension-10,andstudythemassandpoleresidueindetailswiththeQCDsumrules.WeobtainthevalueM_X=(5.57±0.12)GeV,whichisconsistentwiththeexperimentaldata.ThepresentpredictionfavorsassigningtheX(5568)tobethescalartetraquarkstate.

简介：TheelectronicpropertiesandtopologicalphasesofThXY(X=Pb,Au,Pt,PdandY=Sb,Bi,Sn)compoundsinthepresenceofspin–orbitcoupling,usingdensityfunctionaltheoryareinvestigated.TheThPtSncompoundisstableintheferromagneticphaseandtheotherThXYcompoundsarestableinnonmagneticphases.Bandstructuresofthesecompoundsintopologicalphases(insulatorormetal)andnormalphaseswithingeneralizedgradientapproximation(GGA)andEngel–Voskogeneralizedgradientapproximation(GGAEV)arecompared.TheThPtSn,ThPtBi,ThPtSb,ThPdBi,andThAuBicompoundshavetopologicalphasesandtheotherThXYcompoundshavenormalphases.Bandinversionstrengthsandtopologicalphasesofthesecompoundsatdifferentpressurearestudied.Itisseenthatthebandinversionstrengthsofthesecompoundsaresensitivetopressureandforeachcompoundasecond-orderpolynomialfittedonthebandinversionstrengths–pressurecurves.

简介：Fe_(3–x)O_4raspberryshapednanostructures/graphenenanocompositesweresynthesizedbyaone-steppolyol-solvothermalmethodtobetestedaselectrodematerialsforLi-ionbattery(LIB).Indeed,Fe_(3–x)O_4raspberryshapednanostructuresconsistoforiginalorientedaggregatesofFe_(3–x)O_4magnetitenanocrystals,ensuringalowoxidationstateofmagnetiteandahollowandporousstructure,whichhasbeeneasilycombinedwithgraphenesheets.TheresultingnanocompositepowderdisplaysaveryhomogeneousspatialdistributionofFe_(3–x)O_4nanostructuresatthesurfaceofthegraphenesheets.TheseoriginalnanostructuresandtheirstronginteractionwiththegraphenesheetsresultedinverysmallcapacityfadinguponLi+ionintercalation.Reversiblecapacity,ashighas660mAh/g,makesthismaterialpromisingforanodeinLi-ionbatteriesapplication.

简介：WehavestudiedtheangularmagnetoresistanceofironpnictidesBaFe2-xNixAs2,whichshowsclear180degreeperiodicityasfittedbyacosinefunction.Inthex=0.065sample,thephaseofthetwo-foldsymmetrychanges90degreesabovethetetragonal-to-orthorhombicstructuraltransitiontemperatureTs.Sincethephaseatlowtemperatureisassociatedwiththerotationoforthorhombicdomainsbymagneticfield,weshowthatevenvacuumgreasecanpushthepresenceoforthorhombicdomainsattemperaturesmuchhigherthanTs.Ourresultssuggestthatresidualstressmayhavesignificanteffectsinstudyingthenematicordersanditsfluctuationsinironpnictides.

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简介：Twotransmissioncurvedcrystalspectrometersaredesignedtomeasurethehardx-rayemissioninthelaserfusionexperimentofComptonradiographyofimplosiontargetonShenGuang-IIIlaserfacilityinChina.Cylindricallycurvedα-quartz(10–11)crystalswithcurvatureradiiof150and300mmareusedtocoverspectralrangesof10–56and17–100keV,respectively.Thedistancebetweenthecrystalandthex-raysourcecanbechangedoverabroaddistancefrom200to1500mm.Theopticaldesign,includingtheintegralreflectivityofthecurvedcrystal,thesensitivity,andthespectralresolutionofthespectrometers,isdiscussed.WealsoprovidemechanicdesigndetailsandexperimentalresultsusingaMoanodex-raysource.High-qualityspectrawereobtained.Weconfirmedthatthespectralresolutioncanbeimprovedbyincreasingtheworkingdistance,whichisthedistancebetweentherecordingmediumandtheRowlandcircle.