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123 个结果
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  • 简介:聆听CD,它会读出巴士将要停靠的站名。画线把这些站名按次序连接起来,地图上会出现一个图形,那是什么东西呢?

  • 标签: 小学 英语 课外阅读 阅读材料
  • 简介:Objective:Thereisnosaferwaytotransportachildthanaschoolbus.FatalcrashesinvolvingoccupantsareextremelyrareeventsintheUS.Inrecentyears,schoolbustransportationbegantodevelopinChina.WewanttobringadvancedexperienceonschoolbussafetyinWesterncountriessuchastheUStodevelopingcountries.Methods:WesearchedthepapersrelatedtoschoolbussafetyfromMedline,ChineseScientificJournalsDatabaseandtheWeboftheNationalHighwayTrafficSafetyAdministration(NHTSA).Results:Therewereonly9papersrelatedtoschoolbussafety,whichshowedthathigherlevelsofsafetystandardsonschoolbuses,schoolbus-relatedtransportationandenvironmentallawsandinjurypreventionweretheprimaryreasonsforthedesiredoutcome.Fewschoolbusisrelatedtodeathsandinjuriesinthedevelopedcountries.Conclusions:Thedevelopingcountriesshouldmakestrictenvironmentallawsandstandardsonschoolbussafetytopreventchildren'sinjuryanddeath.

  • 标签: 儿童 安全 交通车 创伤
  • 简介:ThelimitsofparameterγinFASTTCParestudiedinthispaper.AcontinuoustimefluidflowmodelofthelinkbufferisconsideredtocreatealinearcontrolsystemrelatedtoFASTTCP.Linearingthefluidflowmodelandwindowcontrolmodel,theLaplacetransformversionofcongestioncontrolsystemarepresented.Itresultsinanegativefeedbacksystemwithopenlooptransferfunction.WiththeanalysisofNyquistcurveofthesystem,asufficientconditiononasymptoticalstabilityofFASTTCPcongestionwindowrelatedtotheparameterγisobtained.Packetlevelns-2simulationsareusedtoverifythetheoreticalclaims.

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  • 简介:TheARGO-YBJexperimentispresentlyunderconstructionattheYangbaijinghighAltitudeComsmicRayLaboratory(4300ma.s.l).90KmNorthtoLhasa(Tibet,peolpl'sRepublicofChina)ARGO-YBJwillstudyfundamentalissuesincosmicrayandastroparticlephysicsbydetectingsmallsizeairshowers.Thedetectorcovers-71×74squaremeterswithasinglelayerofresistivePlateCounters(RPCs),surroundedbyaguardringpartiallyinstrumented.Anevent-drivendatacollectionschemeisimplementedbyusingacustombusprotocol./Keyfeaturesofthisarchitectureareblock-orienteddatatransferandread-outcycleslabeledbytriggernumber,HardwareenginesinbothmasterandDAQboardshandlebustransactionsandprovideeventbuilingcapability,achievingreal-timedataprocessingwithnosoftwareoverhead.InthispaperwepresentthehardwaredesignoftheARGOexperiment'sDAQwhichbenefitsfromtheflexiblearchitectureofin-systemreconfigurableFPGAs.Thedataacquistitionboardsspecificallydevelopedforthisapplicationwillbedescribed.

  • 标签: ARGO-YBJ实验 宇宙线 探测器
  • 简介:Thereal-timedispatchingmodelonbussystemisstudiedinthisarticle.Realtimedispatchingcanresumetheplannedschedulequickly,andthentoensurethereliabilityofthepublictransportserviceandtowellraisetheservicequality.

  • 标签: 公共运输 实时调遣 可靠性 服务质量
  • 简介:随着网络规模的增长,端系统提供给网络的负载不断加大,网络拥塞已经成为一个十分严重的问题,表现为数据报延时、丢弃概率增加、上层应用性能下降等。网络拥塞控制算法对于网络的稳定运转起着十分重要的作用。近年来,对因特网的拥塞控制机制进行了大量的研究,提出了许多新算法和改进算法。本文对端到端的TCP拥塞控制算法进行了详细的分析,并指出了TCP拥塞控制算法的进一步研究方向。

  • 标签: INTERNET 拥塞控制 TCP
  • 简介:DuetotheproblemsarisingwhentheTransmissionControlProtocol(TCP)isappliedoverwirelessnetworks,manyTCPperformanceenhancementmechanismshavebeenproposed.However,suchmechanismsaren'tcompatiblewithIPSecprotocol.ThepaperreviewstheTCPperformanceenhancementmechanismsinwirelessnetworks.Thentheconflictsbetweenthemareanalyzed.Severalproposalsforsolvingtheconflictsarediscussed,andtheirbenefitandlimitationsareexamined.

  • 标签: TCP IPSEC WIRELESS NETWORK
  • 简介:TCP/IP是网络的一个重要的协议.在安装Linux系统中.网络的构建是离不开这个协议的。它的情况好坏与网络的质量有着直接的关联.很多时候,我们并不知道或不了解网络通信各方面的连接情况。要想了解网络状况一般是要依靠一些工具来实现的。本文将介绍一个追踪并图形显示TCP/IP网络状况的工具——bandwidthd,通过这个工具能方便地知道TCP/IP的网络使用状况。

  • 标签: 图形显示 TCP/IP LINUX系统 bandwidthd 网络使用状况 GPL授权