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24 个结果
  • 简介:Theinfluenceofinitialstrainstateonthedynamicresponseofanendbearingpileembeddedinisotropicsaturatedsoilisinvestigatedthroughthelinearizedtheoryofsmallelasticperturbationsuperposedonlargelystressedbodies.Thegoverningequationsforsoil,basedonBiot’sporoelasticitytheory,arederivedinthecylindricalcoordinates,andthepileismodeledbyusingtheone-dimensionalelastictheory.Theanalyticalsolutionsofpileimpedance,frequencyresponseofbothtwistangleandtimehistoryofvelocityresponseareobtainedbyusingofseparationofvariablestechnique.Finally,aparametricstudyoftheinfluenceofinitialstrainsonthetorsionalimpedance,twistangle,andvelocityresponseatthetopofthepileiscarriedout.

  • 标签: 力学 流体力学 粘性流体力学 边界层
  • 简介:Fora〈r〈b,theapproachofLiandZhou(2014)isadoptedtofindjointLaplacetransformsofoccupationtimesoverintervals(a,r)and(r,b)foratimehomogeneousdiffusionprocessbeforeitfirstexitsfromeitheraorb.Theresultsareexpressedintermsofsolutionstothedifferentialequationsassociatedwiththediffusionsgenerator.Applyingtheseresults,weobtainmoreexplicitex-pressionsonthejointLaplacetransformsofoccupationtimesforBrownianmotionwithdrift,BrownianmotionwithalternatingdriftandskewBrownianmotion,respectively.

  • 标签: Laplace transform OCCUPATION time time-homogeneous diffusion
  • 简介:ThesynchrodoublepulsesignalmodeisfreuqentlyusedinShortBaseLine(SBL)underwaterpositioningsystemsoastoobtaintheinforma-tionofbothdistanceanddepthofatargetsimultaneously.Howerer,thissignalmodealsobringsaboutrangingindistinctnessresultinginashorterpositioningdistancemuchlessthanthatlimitedbytheperiodofthesynchrosignal.Thispaperpresentsahardwaredistance-gatedataacquiringscheme.Itputstheoriginaldatasenttothecomputerinorderof"directfirstpulse—depthinformationpulse(orfirstpulsereflectedbywatersurface)…"toguaranteetheeffectivepositioningdistanceofthesystem.Ithastheadvan-tageofreducingtheprocessingtimeofthecomputerthusensuringtherealtimefunctioningofthesystem.Afigureoftheorbitofanunderwatermovingtargetmeasuredinpracticeisattachedtotheendofthepaper.

  • 标签: positioning underwater reflected GUARANTEE FIGURE acquiring
  • 简介:Pre-stackmigrationimaging(PMI)method,whichisusedingeophysicalexplorationbytheperformanceofsinglesidedetectionandvisuallydisplay,canbeusedtoidentifythelocation,orientation,andseverityofdamagesinconcretestructure.Inparticular,thisletterfocusesontheexperimentalstudybyusingafinitenumberofsensorsforfurtherpracticalapplications.Aconcretestructurewithasurface-mountedlinearPZTtransducersarrayisillustrated.Threetypesofdamages,horizontal,dippingandV-sha...

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  • 简介:这份报纸面对一个电的偏导领域与内在的有限变丑在软electroactive柱体学习波浪繁殖。为electroelasticity和联系线性增长理论基于一个最近建议的非线性的框架,管理axisymmetric波浪的基本方程在柱体打手势,它受到同类预先拉长并且先存在的轴的电的排水量,当electroactive材料各向同性、不可压缩时,被介绍。准确波浪答案然后被导出以(修改)Bessel函数。为非线性的electroactive材料的一个原型模型,解说性的数字结果被给。这被显示出效果预先拉长并且电的偏导地能在波浪繁殖特征上是重要的。

  • 标签: 预拉伸 电化学 EXACT SOFT 贝塞尔函数 有限变形
  • 简介:AdynamicalLangevinmodelisemployedtoevaluatetheexcessoftheneutronemissioninthefissionofheavynuclei~(240)Cf,~(246)Cf,~(254)Cf,~(240)Urelativetothestandardstatistical-modelpredictionatvarioussaddle-to-scissionfrictionstrengths.Itisshownthatwhentheneutron-to-protonratioN/Zofthesystemincreases,thesensitivityoftheexcesstothefrictiondecreasessubstantially,anditalmostdisappearsfor~(240)U.WesuggestthatusingthosecompoundsystemswithlowN/Zfavorsanaccuratedeterminationforthesaddle-to-scissionfrictionstrengthbasedonthemeasurementofthepre-scissionneutronmultiplicity.

  • 标签: 动力学模型 中子 重核裂变 裂解
  • 简介:预先滑动的政体典型地在机械系统的动态建模被忽视。然而,处于静态的磨擦引起的接触状态的变化可以减少位置的精确性和控制精确。为了调查在接触之间的关系,地位和接触在预先滑动强迫磨擦,一个光试验性的方法在这份报纸被介绍。与这个方法,在透明材料的接口的真实接触状态能被使用处理技术的一幅图象基于光的全部的思考原则观察。新奇安装,包括一双矩形的trapezoidal块,被建议解决精确地把不同正切、正常的力量用于接触接口的挑战性的问题。改进Otsus方法被用于测量。通过在polymethylmethacrylate(PMMA)上执行的试验性的研究,接触粗糙的数量被证明是影响真实接触区域的主导的因素。在在预先滑动的政体的真实接触区域和接触力量之间的关系被学习,并且在接触接口的静态的磨擦的分发是讨论的品质上。真实接触区域与增加静态的磨擦一起在膨胀的新现象被识别。上述的关系在在一个经常的正常压力下面的接触接口是近似线性的,并且磨擦应力的分发从前缘减少到后面的边。

  • 标签: 真实接触面积 滑动状态 接触力 聚甲基丙烯酸甲酯 接触状态 静摩擦力
  • 简介:Inthispaper,anewdevelopedmulti-channelpre-processingcircuitforsignalsfromtemperaturesensorwasintroducedinbrief.Thiscircuitwasdevelopedtocollectandamplifythesignalsfromtemperaturesensor.Thisisauniversalcircuit.Itcanbeusedtoprocessthesignalsfromthermocouplesandalsousedtoprocesssignalsfromthermistors.Thiscircuitwasmountedinastandardbox(440W×405D×125Hmm)asaninstrument.The

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  • 简介:Carbon-manganesesteelisoftenappliedincomponentsofpipesinnuclearplant.Ultrasonicfatiguetestsfollowinglowcyclefatigue(LCF)cyclesdamagedareusedtostudythestrengthofveryhighcyclefatigure(VHCF).ThecomparisonoftestresultsofsimpleVHCFandcumulativefatigue(LCFplusVHCF)showsthatLCFloadinfluencesthefollowingVHCFstrength.ContinuumdamagemechanicsmodelisextendedtoVHCFregion.TheeffectofLCFloadonVHCFisstudiedbyanimprovedcumulativedamagemodel.

  • 标签: 低周疲劳破坏 高周疲劳 超声疲劳试验 损伤力学模型 组成部分 比较试验
  • 简介:Wepresentthedesignandexperimentofabroadbandopticalparametricchirped-pulseamplifier(OPCPA)whichprovideshighconversionefficiencyandgoodbeamqualityat808nmwavelength.Usingathree-dimensionalspatialandtemporalnumericalmodel,severaldesignconsiderationsnecessarytoachievehighconversionefficiency,goodbeamqualityandgoodoutputstabilityarediscussed.Toimprovetheconversionefficiencyandbroadentheamplifiedsignalbandwidthsimultaneously,thenonlinearcrystallengthandOPCPAparametersareanalyzedandoptimizedwiththeconceptofdissipatingamplifiedidlerbetweenopticalparametricamplification(OPA)oftwocrystalsconfiguration.Intheexperiment,anamplifierconsistingoftwoOPCPAstagesof‘L’typeconfigurationwasdemonstratedbyusingtheoptimizedparameters.Anamplifiedsignalenergyof160mJwasachievedwithatotalpump-to-signalefficiencyof35%(43%efficiencyfortheOPCPAstage2).Theoutputbandwidthofsignalpulsereached80nmandthesignalpulsewascompressedto24fs.Theenergystabilityreached1.67%RMSat3%pumpenergyvariation.TheoptimizedOPCPAamplifieroperatesatarepetitionrateof1Hzandisusedasafront-endinjectionforthemainamplifierofSG-II5PWlaserfacility.

  • 标签: BBO nonlinear optics optical parametric chirped-pulse
  • 简介:Twograftingmethods,i.e.solutiongraftingandpre-adsorbing,areintroducedtocovalentlyimmobilizehydrophilicpolymersonsegmentedpolyurethane(SPU)tomodifyitshydrophilicityandtoimproveitscellcompatibility.Solutiongraftingresultsinhigherdegreeofgraftingandroughersurfacemorphology.Cellcultureevaluationdemonstratesthatthemodifiedmembranesthusobtainedaredisadvantageoustotheendothelialcell(ECs)growthprobablybecausethehydrophilicgroupsonthesurfaceareover-crowded.However,pre-absorbinggraftinggenerateslowerdegreeofgrafting,whichisdetectedandconfirmedbyATR-FTIRspectraandwatercontactangle.Scanningelectronmicroscopic(SEM)measurementshowsthatthelattermethodproducesaplaneandsmoothmorphology,whichissimilartotheSPUcontrolsamplecontrolled.Whengraftingwithlowermonomerconcentration,ECscouldgrowonSPU-g-PHEA[poly(2-hydroxyethylacrylate)],SPU-g-PAAm(polyacrylamide),SPU-g-PDMA[poly(2-(dimethylamino)ethylmethacrylate)]orquaternizedSPU-g-PDMAsurfacewithelongatedcellshapes.Hence,thecellcompatibilityofSPUisimprovedandausefulmethodtoconstructacellcompatiblelayeronthepolymersurfacehasbeendeveloped.``

  • 标签: SEGMENTED polyurethane CELL compatibility Surface grafting
  • 简介:Differentoxygenandnitrogencontainingfunctionalgroupswerecreatedonthesurfaceofthemultiwalledcarbonnanotubes.Themulti-walledcarbonnanotubesweretreatedinultrasonicbathwithsulfuricornitricacid.Furthermorethesurfacetexturewasmodifiedbyincreaseoftheroughness.Inparticularaftertreatmentwiththeoxidizingnitricacid,incomparisontotheH_2SO_4orultra-sonictreatedsamples,cratersandedgesaredominatingthesurfacestructures.Manganeseoxidewasdepositedonthemultiwalledcarbonnanotubesbyprecipitationmechanism.Variousmanganeseoxidesareformedduringthedepositionprocess.Thesampleswerecharacterizedbyelementalanalysis,microscopy,thermalanalysis,Ramanspectroscopy,andbythezetapotentialaswellasX-raydiffractionmeasurements.Itwasshownthatthedepositedmanganeseoxidesarestabilizedratherbysurfacetextureofthemulti-walledcarbonnanotubesthanbycreatedfunctionalgroups.

  • 标签: 多壁碳纳米管 预处理程序 催化剂载体 氧化锰 X射线衍射测量 含氮官能团
  • 简介:Thefirstexperimentalmeasurementsofintense(~7×1019Wcm-2)laser-driventerahertz(THz)radiationfromasolidtargetwhichispreheatedbyanintensepulseoflaser-acceleratedprotonsisreported.ThetotalenergyoftheTHzradiationisfoundtodecreasebyapproximatelyafactorof2comparedtoacoldtargetreference.Thisisattributedtoanincreaseinthescalelengthofthepreformedplasma,drivenbyprotonheating,atthefrontsurfaceofthetarget,wheretheTHzradiationisgenerated.TheresultsshowtheimportanceofcontrollingthepreplasmascalelengthforTHzproduction.

  • 标签: TARGET HEATING TERAHERTZ RADIATION
  • 简介:Conditionsaregivenforcontrollability,outputcontrollabilityandlocalidentifiabitityofaparametrizationinasubsetofoflineardifferentialsystemswithtime-lags.

  • 标签: 删出 舶脚 广州 可口
  • 简介:Thispaperintroducesajointnonlinearityandchromaticdispersionpre-compensationmethodforcoherentopticalorthogonalfrequency-divisionmultiplexingsystems.Theresearchresultsshowthatthismethodcanreducethewalk-offeffectandcanthereforeequalizethenonlinearimpairmentseffectively.Comparedwiththeonlyotherexistingnonlinearitypre-compensationmethod,thejointnonlinearityandchromaticdispersionpre-compensationmethodisnotonlysuitableforlow-dispersionopticalorthogonalfrequency-divisionmultiplexingsystem,butalsoeffectiveforhigh-dispersionopticalorthogonalfrequency-divisionmultiplexingtransmissionsystemwithhigherinputpowerbutwithoutopticaldispersioncompensation.Thesuggestedsolutiondoesnotincreasecomputationcomplexitycomparedwithonlynonlinearitypre-compensationmethod.For40Gbit/scoherentopticalorthogonalfrequency-divisionmultiplexing20×80kmstandardsingle-modefibresystem,thesuggestedmethodcanimprovethenonlinearthreshold(forQ>10dB)about2.7,1.2and1.0dB,andthemaximumQfactorabout1.2,0.4and0.3dB,for2,8and16ps/(nm·km)dispersioncoefficients.

  • 标签: 正交频分复用系统 非线性损伤 色散补偿 相干光 预补偿 补偿方法