学科分类
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52 个结果
  • 简介:【写作要求】假如你是新闻专业毕业生李明,你在杂志BeijingReview上看到一家报社招聘记者的广告。请写一封信给这家报社。要点如下:

  • 标签: 中等教育 英语 阅读 理解
  • 简介:Brainisthemostcomplexorganofhumanbeings.Thecompleteunderstandingofhumanbrains’functionsisanongoingchallengeforneuroscience.Althoughtherearemanytechniquesusedforbrainresearch,neuroscientists,physicists,andengineersarestillexploringotheraccessofresearchforapplications.Terahertz(THz)spectroscopyandimagingmaycreatesuchaspaceforbrainresearch.THzspectroscopictechnique,whichisanovelmedicalimagingmodality,attractsattentionofbiomedicalapplicationsduetoitsuniquefeaturesincludingnon-invasive,non-ionizing,andhighsensitivitytobiomoleculesandtissues.Inthisarticle,weintroduceourrecentinvestigationsonneuroscienceusingTHztechniques,meanwhile,introduceother’sworkinthisfield.Ourandothers’investigationsindicatethattheTHzspectroscopyandimagingtechniquecanbeusefulfordiagnosingbraintumorsandneurodegenerativediseases.THzspectroscopyandimaginghasthepotentialtobecomereal-timeinvivodiagnosticmethods.

  • 标签: 生物医学应用 成像技术 神经科学 太赫兹 神经退行性疾病 光谱技术
  • 简介:Inthispaper,theauthorsintroduceakindofreduciblealgebroidfunctions,thatisgeneralalgebroidfunctionsandobtaintwofundamentaltheoremsofgeneralalgebroidfunctions.Atlast,asanapplication,wegeneralizedatheoremofLiGuoping’s.

  • 标签: 代数体函数 应用 定理 可约
  • 简介:Nuclearfusionhasenormouspotentialtogreatlyaffectglobalenergyproduction.Thenext-generationtokamakITER,whichisaimedatdemonstratingthefeasibilityofenergyproductionfromfusiononacommercialscale,isunderconstruction.Wallerosion,materialtransport,andfuelretentionareknownfactorsthatshortenthelifetimeofITERduringtokamakoperationandgiverisetosafetyissues.Thesefactors,whichmustbeunderstoodandsolvedearlyintheprocessoffusionreactordesignanddevelopment,areamongthemostimportantconcernsforthecommunityofplasma-wallinteractionresearchers.Todate,lasertechniquesareamongthemostpromisingmethodsthatcansolvetheseopenITERissues,andlaser-inducedbreakdownspectroscopy(LIBS)isanidealcandidateforonlinemonitoringofthewallsofcurrentandnext-generation(suchasITER)fusiondevices.LIBSisawidelyusedtechniqueforvariousapplications.Ithasbeenconsideredrecentlyasapromisingtoolforanalyzingplasma-facingcomponentsinfusiondevicesinsitu.ThisarticlereviewstheexperimentsthathavebeenperformedbymanyresearchgroupstoassessthefeasibilityofLIBSforthispurpose.

  • 标签: LIBS NUCLEAR fusion plasma-facing COMPONENTS
  • 简介:Thepedestalcharacteristicisanimportantbasisforhighconfinementmode(Hmode)research.BecauseofthefinitespatialresolutionofThomsonscattering(TS)diagnosticonExperimentalAdvancedSuperconductingTokamak(EAST),itisnecessarytocharacterizethepedestalwithasuitablefunctionalform.BasedonsimulatedandexperimentaldataofEAST,itisshownthatthetwo-linemethodwithabilinearfittinghasbetterreproducibilityofpedestalparametersthanhyperbolictangent(tanh)andmodifiedhyperbolictangent(mtanh)methods.ThismethodhasbeenappliedtoEASTtypeIedgelocalizedmode(ELM)discharges,andtheelectronpedestaldensityisfoundtobeproportionaltotheline-averageddensityandtheedgepressuregradientisfoundtobeproportionaltothepedestalpressure.Furthermore,theionpoloidalgyro-radiushasbeenidentifiedasthesuitableparametertodescribethepedestalpressurewidth.

  • 标签: 基座结构 应用 超导托卡马克 双曲正切 实验数据 压力梯度
  • 简介:Astheevolutionofmobiletechnology,mobiledeviceshavebecomeanessentialtoolinpeople’sdailylife.Moreover,withtherapidgrowthofInternetandmobilenetworks,peoplecaneasilyaccessvariousservicesprovidedbymobileplatforms.Manyservicescanbeexecutedonthemobiledeviceswithvariousmobileapplicationslaunchedtomobileplatforms.Peoplecanchoosewhattheyliketoinstallintheirmobiledevicesandhencemaketheirlifemoreconvenient,entertaining,andproductive.However,therearetoomanymobileapplicationsforuserstochoose.Thegoalofthisresearchistoproposeamethodologywhichcanrecommendtop-Nlistsformobileapplications.Acommentcorrelationmatrixisproposed.Furthermore,arecommendationalgorithmformobileapplicationsbasedonusercommentsandkeyattributesisbuilt.Withtheproposedmethod,itoutperformsGoogleplayandisclosertouserrealfeelings.

  • 标签: Comment correlation matrix mobile applications recommendation system user comment
  • 简介:Regimeswitching,whichisdescribedbyaMarkovchain,isintroducedinaMarkovcopulamodel.Weprovethatthemarginals(X,H~i),i=1,2,3oftheMarkovcopulamodel(X,H)arestillMarkovprocessesandhavemartingaleproperty.Inthisproposedmodel,apricingformulaofcreditdefaultswap(CDS)withbilateralcounterpartyriskisderived.更多还原

  • 标签: COPULA 马尔科夫 模型 应用 政权 马尔可夫过程
  • 简介:Multipaction,causedbythesecondaryelectronemissionphenomenon,hasbeenachallengeinspaceapplicationsduetotheresultingdegradationofsystemperformanceaswellasthereductionintheservicelifeofhighpowercomponents.Inthispaperwereportanovelapproachtorealizeaneffectiveincreaseinthemultipactionthresholdbyemployingmicro-poroussurfaces.Twomicro-porousstructures,i.e.,aregularmicro-porousarrayfabricatedbyphotolithographypatternprocessingandanirregularmicro-porousarrayfabricatedbyadirectchemicaletchingtechnique,areproposedforsuppressingthesecondaryelectronyield(SEY)andmultipactionincomponents,andthebenefitsarevalidatedboththeoreticallyandexperimentally.Thesesurfaceprocessingtechnologiesarecompatiblewiththemetalplatingprocess,andoffersubstantialflexibilityandaccuracyintopologydesign.Thesuppressioneffectisquantifiedforthefirsttimethroughtheproperfittingofthesurfacemorphologyandthecorrespondingsecondaryemissionproperties.Insertionlosseswhenusingthesestructuresdecreasedramaticallycomparedwithregularmillimeter-scalestructuresonhighpowerdielectricwindows.SEYtestsonsamplesshowthatthemaximumyieldofAg-platedsamplesisreducedfrom2.17to1.58fordirectlychemicaletchedsamples.MultipactiontestingofactualC-bandimpedancetransformersshowsthatthedischargethresholdsoftheprocessedcomponentsincreasefrom2100Wto5500Wforphotolithographypatternprocessingand7200Wfordirectchemicaletching,respectively.Insertionlossesincreasefrom0.13dBtoonly0.15dBforbothsurfacetreatmentsinthetransmissionband.Theexperimentalresultsagreewellwiththesimulationresults,whichoffersgreatpotentialinthequantitativeanti-multipactiondesignofhighpowermicrowavecomponentsforspaceapplications.

  • 标签: 高功率微波器件 空间应用 微放电 抑制方法 化学蚀刻技术 次级电子发射
  • 简介:在我们担心的一些海区域附近获得长期的观察数据的尝试通常在很难或甚至不可能实际近海并且海洋工程状况。在这份报纸,借助于线性吝啬平方的评价方法,扩大短期的数据到长期的一个新方法被开发。长期的数据关于有关海,区域能经由从邻居获得的一系列长期的数据被构造海洋学的车站,通过不同数据的关联分析系列。在在多重线性回归模型采用的可变数字的数据系列,以及限制的长度之上盖住时间系列预言方法overdependence的不足是有效的。当分析数字选择的例子引用完成海洋学的车站,从位于山东半岛的三个海洋学的车站收集的暴风雨巨浪数据被拿(邻近concerning海区域)并且在为参考并且为分别地设计工程建设被选择的海地点之间的关联系数。由比较N年回来时期,计算从的价值观察了未加工的数据并且处理了借助于线性吝啬平方的评价方法从有限数据系列被扩大的数据,一个人能得出这个方法能在实际海洋工程给更加好的评价的一个结论,尽管有关于未加工、处理的数据的不同的极端值分布。

  • 标签: 线性均方估计 海洋工程 时间序列预测方法 多元线性回归模型 应用 数据序列
  • 简介:Compressivesensing(CS)hasemergedasanovelsamplingframeworkwhichenablessparsesignalacquisitionandreconstructionwithfewermeasurementsbelowtheNyquistrate.AnimportantissueforCSistheconstructionofmeasurementmatrixorsensingmatrix.Anewdeterministicsensingmatrix,namedasOOC-B,isproposedbyexploitingopticalorthogonalcodes(OOCs),BernoullimatrixandSingerstructure,whichhastheentriesof0,+1and-1beforenormalization.Wehaveproventhatthedesigneddeterministicmatrixisasymptoticallyoptimal.Inaddition,theproposeddeterministicsensingmatrixisappliedtodirectionofarrival(DOA)estimationofnarrowbandsignalsbyCSarrays(CSA)processingandCSrecovery.TheoreticalanalysisandsimulationresultsshowthattheproposedsensingmatrixhasgoodperformanceforDOAestimation.ItisveryeffectiveforsimplifyinghardwarestructureanddecreasingcomputationalcomplexityinDOAestimationbyCSAprocessing.Besides,lowerrootmeansquareerror(RMSE)andbiasareobtainedinDOAestimationbyCSrecovery.

  • 标签: DOA估计算法 测量矩阵 波达方向(DOA)估计 应用 窄带信号 硬件结构
  • 简介:Besidesthebiologicalgrowthfactors,smallorganicmolecules,andchemicalions,physicalsignalsistheothercategoryofveryimportantfactorstotune/regulatethefateofstemcells.Recentyears,moreattentionhasbeenpaidonthedifferentiationofstemcellsonthephysicalsignal,including,electricormagneticfield,surfacetopologyofbiomaterials,photoirradiation,andevenpressureandstrainfromthematerials.With

  • 标签: 英语 阅读 理解 纳米材料与技术