简介：TheX-discontinuity,whichappearsatthedepthofapproximately300km,isanimportantseismicinterfacewithpositivevelocitycontrastsintheuppermantle.Detectingitspresenceandtopographycanbeusefultounderstandphasetransformationsofrelevantmantlemineralsunderthehigh-temperatureandhigh-pressurecircumstanceoftheEarth'sinterior.Inthisstudy,wedetecttheX-discontinuitybeneaththeRyukyusubductionzoneusingfiveintermediate-deptheventsrecordedbythedenseAlaskaRegionalNetwork(AK).TheX-discontinuityissuccessfullyrevealedfromtherobustslantstackingofthesecondarydown-goingandconvertingSdPphases.Fromthedepthdistributionofconversionpoints,wefindthattheX-discontinuity'sdepthrangesbetween269kmand313km,withanaveragedepthof295km.Alltheconversionpointsarelocatedbeneaththedown-dippingsideofthePhilippineSeaslab.Fromenergycomparisonsinvespagramsforobservedandsyntheticseismograms,thestrongconvertedenergyismorelikelyfromathinhigh-velocitylayer,andtheS-wavevelocityjumpsacrosstheX-discontinuityareupto5%to8%withanaverageof6.0%.Accordingtopreviouspetrologicalandseismologicalstudies,theX-discontinuitywedetectedcanbeinterpretedasthephasetransformationofcoesitetostishoviteineclogiticmaterialswithintheoceaniccrust.

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简介：Thisstudyconcernsatwo-dimensionalmodelandthecorrespondingvirtualcrackclosuretechnique(VCCT)implementedtosolvethegeneralboundaryvalueproblemsthatmayexplainwhyinterfacediscontinuityhaseffectsonthefracturebehaviorinthesuperconductor-substratesystem.Theinterfacialdiscontinuitycanbeclassifiedaccordingtothematerialproperties'continuityandtheirderivatives'continuityattheinterface.Fornonhomogeneoussuperconductorandsubstratespecimenswithvariousmaterialproperties,aVCCTmethodisdevelopedtocalculatetheirfracturebehavior.Furthermore,theeffectsofappliedmagneticfieldamplitudeandnonhomogeneousparametersareextensivelyandparametricallystudiedintwoactivationprocesses(zero-fieldcoolingandfieldcooling).Theintegrativeandcomputationalstudypresentedhereprovideafundamentalmechanisticunderstandingofthefracturemechanisminthesuperconductor-substratesystemandshedslightontherationaldesignofinterfacialcontinuity.

简介：Thispaperisconcernedwithasingularlimitfortheone-dimensionalcompressibleradiationhydrodynamicsmodel.ThesingularlimitweconsidercorrespondstothephysicalproblemoflettingtheBouguernumberinfinitewhilekeepingtheBoltzmannnumberconstant.InthecasewhenthecorrespondingEulersystemadmitsacontactdiscontinuitywave,WangandXie（2011）[12]recentlyverifiedthissingularlimitandprovedthatthesolutionofthecompressibleradiationhydrodynamicsmodelconvergestothestrongcontactdiscontinuitywaveintheL∞-normawayfromthediscontinuitylineatarateofε14,asthereciprocaloftheBouguernumbertendstozero.Inthispaper,WangandXie’sconvergencerateisimprovedtoε7/8byintroducinganewaprioriassumptionandsomerefinedenergyestimates.Moreover,itisshownthattheradiationfluxqtendstozerointheL∞-normawayfromthediscontinuityline,ataconvergencerateasthereciprocaloftheBouguernumbertendstozero.

简介：Asglobaltemperaturesincreaseanddissolvedoxygen(DO)contentdecreasesinmarinesystems,indicesassessingsedimentDOcontentinbenthichabitatsarebecomingincreasinglyuseful.Onesuchmeasureisthedepthtotheapparentredoxpotentialdiscontinuity(aRPD),atransitionofsedimentcolorthatservesasarelativemeasureofsedimentDOcontent.WeexaminedspatiotemporalvariationofaRPDdepth,andthenatureoftherelationshipsbetweenaRPDdepthandbiotic(infaunaandepibenthicpredators)andabioticvariables(sedimentproperties),aswellastheavailabilityofresources(chlorophyllaconcentration,andorganicmattercontent)intheintertidalmudflatsoftheBayofFundy,Canada.aRPDdepthvariedsignificantlythroughspaceandtime,andacombinationofbiotic(sessileanderrantinfauna,aswellasepibenthicpredators),andabiotic(exposuretimeofaplot,sedimentparticlesize,penetrability,andwatercontent)variables,aswellastheavailabilityofresources(sedimentorganicmattercontent,andchlorophyllaconcentration)werecorrelatedwithaRPDdepth.Assuch,knowledgeofbothbioticandabioticvariablesarerequiredforaholisticunderstandingofsedimentDOconditions.AbioticvariableslikelydictateasuiteofpotentialaRPDdepthconditions,whilebiotaandresourceavailability,viabioturbationandrespiration,stronglyinfluencetheobservedaRPDdepth.AsDOconditionsinmarinesystemswillcontinuetochangeduetoglobalclimatechange,elucidatingtheserelationshipsareakeyfirststepinpredictingtheinfluencedecreasingDOcontentmayhaveuponmarinebenthos.&2017InternationalResearchandTrainingCentreonErosionandSedimentation/theWorldAssociationforSedimentationandErosionResearch.PublishedbyElsevierB.V.Allrightsreserved.

简介：代数课本中指出:“在a>0时,|x|>a(?)x<-a或x>a;|x|0”。其实,这一等价性在a≤0时也同样成立。现证明如下:①当a=0吋,i|x|>a即|x|>0的解集显然是:x<0或x>0即x<-a或x>a。

简介：通过变量代换对于形如a(x)y″(x)+b(x)y′(x)+c(x)y=0的函数系数二阶常微分方程，当系数函数满足一定条件时，可以化为二阶常系数齐次微分方程。

简介：命题：若＂{x≥a,x≤a,则x=a＂，体现了＂相等＂与＂不等＂的对立统一及其相互转化的关系．命题虽然十分简单，却在解答数学竞赛试题中发挥重要作用．本文举例介绍其应用．

简介：“X声X气”这种格式具有较强的能产性。“X”是同一个语素的很多，有名词性、动词性、象声词性、副词性语素，形容词性语素更常见；前后两个“X”虽是同一词性但不是同一语素的也有不少，还有前后两个“X”不属同一词性的语素的：同“X里X气”格式一样，“X声X气”绝大多数表贬义，表中性的很少，表褒义的更少，因此它多为形容词。“X声X气”可用作主语、谓语、宾语、定语、状语、补语，而以作状语的为最常见，作定语的次之。

简介：函数f（x）=sinx/x有许多重要的性质及优美结论，本文主要谈谈它的重要性质与同行共飨．

简介：浅谈公式ｘ２＋（ａ＋ｂ）ｘ＋ａｂ＝（ｘ＋ａ）（ｘ＋ｂ）遂宁安居镇中学何旭东十字相乘法是因式分解的一种方法，其灵活性大，难度高。现行义务教材用它分解二次项系数为１和二次项系数不为１的二次三项式，但未提及双十字相乘法。现在我们用公式：ｘ２＋（ａ＋ｂ）ｘ＝...

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简介：如果说有一本小说标榜一个文学世代。成为日后叛逆青年的圣经,甚至蔚为一种生活态度,影响时尚流行,那么《OntheRoad》这部美国战后文学经典可以称做代表。它以半自传式的散文体,描写颓废漂泊的作家和年轻友人在无际的美洲公路浪游,体现自由、友谊、爱和狂欢的生命本质,可以说是"ontheRoad"一词的由来。

简介：论述在极限教学中应注意的几个问题,给出一种证明函数极限的方法

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简介：由系统x^..＋f（x，x^.）x^.＋g（x）=0的内侧轨线找外侧轨线，再由庞卡莱定理推知系x^..＋f（x，x^.）x^.＋g（x）=0存在稳定极限环．

简介：Inthispaperwegivetheexactorderof丨x-xk丨丨lk（x）丨foranyfixednonnegativeintegerssandt,whichisn-s,n-slnnandn1-fors≤t-2,s=t-1ands≥t,respectively.

简介：摘 要： “应X尽X”“X码”族词语都在新冠疫情中得到了发展和衍生。文章以“应X尽X”族和“X码”族词语为研究对象，在研读相关文献的基础上，运用语言学的相关知识，分析其内部构成、造词理据和语用价值等问题。