简介：语言习得是指一个人习得语言的过程。儿童与成人之间的区别导致第一语言和第二语言习得的差异。本文从语言认知和情感因素两方面做深入分析，对第一语言和第二语言习得的差异进行比较和对照。

简介：Inordertoidentifythelocationsofirreversiblelosswithinthetranscriticalcarbondioxiderefrigerationcyclewithanexpansionturbine,amethodwithrespecttothesecondlawofthermodynamicsbasedonexergyanalysismodelisapplied.Theeffectsofheatrejectionpressures,outlettemperaturesofgascoolerandevaporatingtemperaturesontheexergyloss,exergyefficiencyandthecoefficientofperformance(COP)oftheexpansionturbinecycleareanalyzed.Itisfoundthatthegreatpercentagesofexergylossestakeplaceinthegascoolerandcompressor.Moreover,heatrejectionpressures,outlettemperaturesofgascoolerandevaporatingtemperatureshavestronginfluenceontheexergyefficiency,COPandtheexergylossofeachcomponent.TheanalysisshowsthatthereexistsanoptimalheatrejectionpressurecorrespondingtothemaximumexergyefficiencyandCOP,respectively.Theresultsareofsignificanceinprovidingtheoreticalbasisforoptimaldesignandthecontrolofthetranscriticalcarbondioxidesystemwithanexpansionturbine.

简介：Code-switchingisasocio-linguisticterm,whichreferstotheswitchingfromonelanguagetoanother.Thispaperattemptstoshowthatcode-switchingcanbeusedasateachingstrategyforsecondlanguageteachingbyillustratingthepossiblereasonsfortheswitching.Italsoexploresthepossibilityofviewingcode-switchingaslanguageinterferenvefromateachingperspective.Inaccordancewiththeseanalysisthispapermakesaconclusionthatwhencode-switchingistocompensateforalanguagecifficultyitmaybeviewedasinterfernceandwhenitisusedasasocio-linguistictoolitbecomesastrategy.

简介：本文对依赖于过去的死亡率和出生率的年龄结构人口动力学模型建立了一个三层特征差分格式，证明了这一差分格式在离散无穷范数下是二阶收敛的

简介：Givenarealfinite-dimensionalorinfinite-dimensionalHilbertspaceHwithaJordanproduct,thesecond-orderconelinearcomplementarityproblem（SOCLCP）isconsidered.Someconditionsareinvestigated,forwhichtheSOCLCPisfeasibleandsolvableforanyelementq？H.ThesolutionsetofamonotoneSOCLCPisalsocharacterized.Itisshownthatthesecond-orderconeandJordanproductareinterconnected.

简介：文章以SecondLife为参照，描述和分析了虚拟世界中的教育活动，从交互空间、信息表征等方面探讨了虚拟世界的教育功用及属性，同时通过实例和数据展开分析。文章最后提出在虚拟世界中开展教育实践将面临的问题和挑战。

简介：Inthispaper,theeffectsofsecond-orderdifference-frequencywaveforcesontheglobalmotionofanoffshorewindturbinesystemwithalargedisplacementunderthesurvivalconditionarestudied.Inthiscase,thehydrodynamicforceisthemainforcebecausethebladesarefeatheredtoreducetheliftingforce.Thefirst-orderhydrodynamicforcesarecalculatedbyWADAM,whilethesecond-orderwaveforcesarecalculatedbyacustomizedMATLABmodule.ThenthehydrodynamiccoefficientsaretransferredtothewindturbineanalyticalcodeFAST.Throughthecomparisonsofdynamicresponsesbetweenthefirst-andsecond-ordernumericalmodels,itisfoundthatthesecond-orderwaveforcessignificantlyinfluencethemotionoffloatingwindturbineunderthesurvivalcondition.Moreover,neglectingthesecond-orderforcesignificantlyunderestimatesthetensionforcesinthemooringlines.