简介:Thispaperdealswithfinitedeformationproblemsofcantileverbeamwithvariablesec-tionundertheactionofarbitrarytransverseloads.Bytheuseofamethodofvariablereplacement,thenonlineardifferentialequationwithvariedcoefficientfortheproblemcanbetransformedintoanequationwithvariableseparable.Theexactsolutioncanbeobtainedbytheintegrationmethod.Someexamplesaregiveninthepaper,andtheresultsoftheseexamplesshowthatthisexactsolutionincludestheexistingsolutionsinreferencesasspecialcases.
简介:摘要:星座中卫星失效会对星座的覆盖性能产生一定的影响,量化这种影响对于评价星座的效能具有显著意义。以STK软件为基础,构建Walker星座后,通过仿真分析部分卫星失效后星座覆盖性能的变化关系,并进一步指定特定区域,分析部分卫星失效后星座对该区域覆盖性能的影响关系。
简介:WithvonMisesyieldcriterion,theloadingrangeofNetSectionCollapse(NSC)Criteriaisextendedfromcombinedtensionandbendingloadingstocombinedbending,torsionandinternalpressureloadings.AnewtheoreticalanalyzingmethodofplasticlimitloadforpressurepipewithincompleteweldingdefectsbasedontheextendedNSCCriteriaispresentedandthecorrelativeformulasarededuced,theinfluencesofpipecurvature,circumferentiallengthanddepthofincompleteweldingdefectsontheplasticlimitloadofpressurepipeareconsideredaswellinthismethod.Meanwhile,accordingtotheorthogonalexperimentaldesignmethod,theplasticlimitloadsarecalculatedbythefiniteelementmethodandcomparedwiththetheoreticalvalues.Theresultsshowthattheexpressionsofplasticlimitloadofpressurepipewithincompleteweldingdefectsunderbending,torsionandinternalpressurebasedonextendedNSCcriteriaarereliable.Thestudyprovidesanimportanttheoreticalbasisfortheestablishmentofsafetyassessmentmeasuretowardspressurepipewithincompleteweldingdefects.
简介:一个纤维节模型基于Timoshenko横梁元素在这研究被建议基于考虑轴的框架元素的非线性的分析,曲折,并且砍变丑。这个模型用砍弯曲被完成相互依赖的明确的表达(SBIF)。元素的形状功能从平衡方程的同类的形式的准确答案被导出因为Timoshenko变丑hypothesis.The建议元素从砍锁是免费的。部分纤维模型与一个多轴的粘性材料模型一起被组成,它被用来模仿每纤维的联合砍轴的非线性的行为。由在纤维之中强加变丑相容性条件,部分、元素的抵抗力量是计算的。因为SBIF形状功能与为节的不同形状的砍修正者因素是交互的,一个反复的过程在建议Timoshenko元素的非线性的州的决心被介绍。另外,建议模型由采用一条corotational坐标转变途径处理几何非线性的问题。为非线性的几何分析的SBIFTimoshenko元素的corotational算法的推导过程被介绍。数字例子证实与一个纤维节模型一起的SBIFTimoshenko元素有象基于灵活性的明确的表达的一样的精确性和坚韧性。最后,SBIFTimoshenko元素被扩大并且demonstratedin一个三维的数字例子。
简介:GuestEditorProf.Dr.StephanieTeufelUniversityofFribourgstephanie.teufel@unifr.chFromenergygenerationtotransportation,fromenergydistributiontostorage,fromsemiconductorprocessingtocommunications,andfromportabledevicestodatacenters,energyconsumptionhasgrowntobeamajorlimitationtousability
简介:WehavestudiedthefragmentationprocessinheavyioncollisionssystematicaIlybyusingIsospin-dependentQuantumMolecularDynamics(IQMD)modelandfoundthatthemultiplicityofintermediatemassfragmentsN_(imf)canbeusedasaprobetoextracttheinformationofin-mediumnmuleon-nucleoncrosssection.Fig.1shows
简介:Anexperimentalstudyonabareflexiblecylinderaswellascylindersfittedwithtwotypesofcross-sectionedhelicalstrakeswascarriedoutinatowingtank.Themainpurposeofthispaperistoinvestigatetheeffectsofstrakes'crosssectiononthevortex-inducedvibrations(VIV)suppressionofaflexiblecylinder.Thesquare-sectionedandroundsectionedhelicalstrakeswereselectedintheexperimentaltests.Theuniformcurrentwasgeneratedbytowingthecylindermodelsalongthetankusingatowingcarriage.TheReynoldsnumberwasintherangeof800–16000.Thestrainresponsesweremeasuredbythestraingagesincross-flow(CF)andin-line(IL)directions.Amodalanalysismethodwasadoptedtoobtainthedisplacementresponsesusingthestrainsignalsindifferentmeasurementpositions.Thecomparisonoftheexperimentalresultsamongthebarecylinder,square-sectionedstrakedcylinderandroundsectionedstrakedcylinderwasperformed.Thehelicalstrakescaneffectivelyreducethestrainamplitude,displacementamplitude,responsefrequenciesanddominantmodesofaflexiblecylinderexcitedbyVIV.Andthemeandragcoefficientsofstrakedcylinderswereapproximatelyconsistentwitheachother.Inaddition,thesquaresectionedandround-sectionedstrakesnearlysharethesimilarVIVreductionbehaviors.Sometimes,thestrakeswithround-sectionrepresentmoreexcellenteffectsontheVIVsuppressionofresponsefrequencythanthosewithsquaresection.
简介:FollowingtheunanimousrecommendationoftheInternationalCommissiononStratigraphy,theGlobalboundaryStratotypeSectionandPoint(GSSP)forthebaseoftheCenomanianStageisdefinedatalevel36metresbelowthetopoftheMarnesBleuesFormation,alevelthatcorrespondstothethefirstappearanceoftheplanktonicforaminiferanRotaliporaglobotruncanoidesSigal,1948,onthesouthsideofMontRisou,eastofRosans,Haute-Alpes,France,whereitcanbeplacedinthecontextofaseriesofsecondarymarkerlevelsbasedonnannofossils,planktonicforaminifera,ammonites,andanornateδ^13Ccurve.