简介:今年4月,看到一则报道说尽管某宽带公司现有技术可以容纳的网络用户容量为400至600万用户,可是目前,在容纳了45万用户的情况下,网络已经拥护不堪,时常出现断网情况,一到上网高峰,网速就会急剧下降,为何网络会如此拥挤不堪?这是因为自从出现诸如电驴、Kazaa、BT等P2P软件之后,海量的数据文件(如大容量文件交换、视
简介:Theletterproposesathree-layermanageablemediadistributionnetworksystemarchi-tecturecalledMSPnet,whichisbasedonSessionInitiationProtocol[1]andPeertoPeer(SIPP2P)technology.MSPnetperformsapplication-levelstructuredDHTroutingandresourcelocationamongdomainsandunstructuredonesindomain.Exceptformediadistribution,itcanbeusedtosupportavarietyofP2Papplications,includingvideobroadcasting,videoondemand,VoIP,etc.MSPnetiscomposedofthreelayers,namely,thesignalcontrollayer,themanagementlayer,andthemediatransportationlayer.TheMSPnetprototypeconsistsoftheSIPserver,themanagementserver,themediaserver,andthenodeUserAgent(UA).Resultsfromaprototypeexperimentinalarge-scaleInternetenvironmentshowthatMSPnetisfeasible,scalableandmanageable.
简介:地理信息系统(GIS)逐渐地正在管理数据的很大的集合,一个因此集中的数据索引不能总是提供最可伸缩的解决方案。最近,p2p(P2P)网络为以一种完全分散的方式分享信息变得很流行。在这份报纸,新混合P2P空间索引网络(HPSIN)被建议,它把分布式的空铅树与基于的分布式的哈希值桌子(DHT)相结合维持询问效率和系统负担的弦网络平衡。另外,一个简单理论模型基于为HPSIN的打开的排队网络被建立。在模型,作为M/M/1排队处理器假定每个同伴系统的基本特征被捕获,并且平均质问延期的表示在靠近的形式被获得。理论分析和数字计算结果证明那在那里存在在效率和负担平衡之间的折衷的一个最佳点。由将开始索引水平ls的合适的值放为不同网络规模和询问率,HPSIN将完成因此,延期能使适应不同P2P应用程序环境的最小的全面询问。
简介:ThedecompositionofalargeamountofunexploitedmacroalgalresourcealongthecoastofChinaoftenresultsinheavyenvironmentalpollution.InordertopaveawayofusingmacroalgaeasthedietaryingredientofrabbitfishSiganuscanaliculatus,oneofafewfarmedherbivorousmarineteleostsinChina,itspreference(feedingselectivity)fordifferentmacroalgaewasdeterminedinthisstudy.SevenseaweedspeciesabundantlyinhabitingthecoastofeastGuangdongProvincewereexposedsimultaneouslytorabbitfishjuvenilesinlaboratory(multiple-choicefeeding)withtheircontentandabsoluteintakeassayed.ItwasfoundthatthemostpreferredalgaewereUlvaprolifera,GracilarialemaneiformisandChaetomorphalinum,lesspreferredalgaewereU.pertusaandPorphyrahaitanensis,andleastpreferredoneswereSargassumfusiformeandCorallinasessilis.Suchanorderdidnotchangewhenonetofourrelativelypreferredseaweedswereremoved.Thepreferredseaweedswerericherinproteinandsolublesugarthushigherinenergythantheleastpreferred.Inaddition,thisfishwasfoundtofavorfilamentousandflatalgaeratherthancalcifiedones.Accordingly,therichnessofnutrientsandmorphologicalcharacteristicsdeterminedthepreferenceofS.canaliculatusfortestedmacroalgae.
简介:LetKbeanalgebraicnumberfieldoffinitedegreeovertherationalfieldQ,andaK(n)thenumberofintegralidealsinKwithnormn.WhenKisaGaloisextensionoverQ,manyauthorscontributetotheintegralpowersumsofaK(n),Σn≤xaK(n)l,l=1,2,3,···.Thispaperisinterestedinthedistributionofintegralidealsconcerningdifferentnumberfields.TheauthorisabletoestablishasymptoticformulaefortheconvolutionsumΣn≤xaK1(nj)laK2(nj)l,j=1,2,l=2,3,···,whereK1andK2aretwodifferentquadraticfields.
简介:Cu和Ni原子经历liquid–solidelectromigration(L-S他们)的散开行为用Cu/Sn/Ni被调查在5.0×103在250°C的2。电子的流动方向显著地影响Cu和Ni原子的跨solder相互作用,即在顺风的散开下面,Cu和Ni原子能扩散到相反的接口;当在迎风的散开,Cuatoms然而并非Ni下面原子能扩散到相反的接口时。当电子从Cu流动到Ni时,仅仅Cu原子扩散到相反的阳极Ni接口,导致从Ni3Sn4进(Cu,Ni)6Sn5并且进进一步[(Cu,Ni)6Sn5+Cu6Sn5],当noNi原子扩散到相反的阴极Cu接口并且这样时界面的Cu6Sn5留下了。从Ni的Whenelectrons流动到Cu,Cu和Ni原子扩散到相反的接口,resultingin从起始的Cu6Sn5进(Cu,Ni)6Sn5并且进进一步[(Cu,Ni)6Sn5+(Ni,Cu)3在阳极Cu接口的Sn4]当时那从起始的Ni3Sn4进(Cu,Ni)6Sn5并且进进一步(Ni,Cu)3在阴极Ni接口的Sn4损坏,电子比另外的方法从Cu流动到Ni是更多的。
简介:Anunderstandingofthetransportmechanismofgravel-bedriversisveryimportantfortherivermanagementandengineeringworks.Themainobjectiveofthisstudywastoconductaseriesoflaboratoryexperimentinasteepflumetoinvestigatetheparticlesegregationandthetransportrateofnonuniformgravel.Mediansizesof15mmand7.5mm,andgradationcoefficientsof1.5and2.0wereselectedfortheparticlesizedistributionsofnonuniformgravel.Inadditiontothe36setsofdatacollectedinthisstudy,635setsofexistingdataforgravelwithbothnonuniformandnearlyuniformsizeswereanalyzed.Accordingtotheresultsofthesieveanalysisandtherelatedtheory,hidingfunctionsforbothparticlesizedistributionsofthisstudywerederived.AnattemptwasmadetodevelopanEinstein-typetransportrelationshipfornonuniformgravelusingdimensionlessparameterswithmeansizeasarepresentativeparticlesize.AmodifiedSchoklitsch-typesedimenttransportequationwithacriticalunitflowdischargewasalsodevelopedtoreasonablypredictthetransportrateofgravels.Inaddition,anartificialneuralnetwork(ANN)modelwithaback-propagationnetwork(BPN)algorithmwasalsoappliedinthisstudy.
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简介:Cathy’s love was civilized and tender . When she fell in love with Linton,Emily Bronte’s Wuthering Heights[M] . San Diego,I am certainly shocked by the love between Heathcliff and Catherine and moved by their deep feelings . And I feel satisfied with the sound ending of Hareton and Cathy . At the same time