简介:在HITS算法的基础上应用蚁群算法的主要思想,对网页按关键字搜索后被点击的次数进行统计,结合相关内容提出了一种新的搜索算法—基于蚁群算法的改进HITS算法.实验表明,该算法在使得返回结果中相关度较高的网页通过人们的自主选择获得了不同程度的加权,使得其在查准率及解决HITS算法的主题漂移方面都优于传统HITS算法.
简介:Uptonow,sometechnologyofneuralnetworksaredevelopedtosolvethenon-linearityofresearchedobjectsandtoimplementtheadaptivecontrolinmanyengineeringfields,andsomegoodresultswereachieved.Thoughitputssomequestionsovertodesignapplicationstructurewithneuralnetworks,itisreallyunknowableaboutthestudymechanismofthose.But,theimportanceofstudyratioiswidelyrealizedbymanyscientistsnow,andsomemethodsonthemodificationofthatareprovided.
简介:<正>Neuralnetworkhastheabilitiesofself-studying,self-adapting,faulttoleranceandgeneralization.Buttherearesomedefaultsinitsbasicalgorithm,suchaslowconvergencespeed,localextremes,anduncertainnumberofimpliedlayerandimpliednotes.Thispaperpresentsasolutionforovercomingtheseshortagesfromtwoaspects.Oneistoadoptprinciplecomponentanalysistoselectstudysamplesandmakesomeofthemcontainsamplecharacteristicsasmanyaspossible,theotheristotrainthenetworkusingLevenberg-Marquardtbackwardpropagationalgorithm.Thisnewmethodwasprovedtobevalidandpracticableinsiteselectionofpracticalgarbagepowergenerationplants.
简介:Abetterunderstandingofthelong-termglobalcarboncyclerequiredestimateofthechangesinterrestrialcarbonstorageafterthelastglacialperiod.Theresultsofsimulationatmid-Holocene(MH)fromPMIP(PaleoclimateModelingIntercomparisonProject)andthemoderndatafromCRU(ClimateResearchUnit,EastAngliaUniversity,UK)allowustousetheAtmosphere-VegetationInteractionModel(AVIM)tosimulatetheChineseterrestrialnetprimaryproductivity(NPP)at6kaBPandpresenttime.ThechangeofNPPandtotalNPPinChinafromnowtomid-Holoceneareabout54gm-2yr-1and0.63Pgyr-1,respectively,mainlyduetothebuild-upoftemperateforestandtropicalrainforest.ChineseterrestrialNPPvariationfromMHtonowiscloselyrelatedtothevariationinintensityofAsianmonsoon,whichcontrolledtheclimate-vegetationpatternchange.
简介:2005年3月23日,BP公司位于德州德克萨斯城的炼油厂发生了死15人、伤170余人的严重爆炸事故。事故调查组提出的内部报告说:BP人员在该炼厂的异构化装置开车前和过程中的一系列失误导致了爆炸和燃烧。装置的抽余馏分切割塔进料过满、然后又升温过高,爆炸时塔中的液位超过了正常允许值近20倍。而在开车过程中塔中可能存在水或氮则造成了塔内压力突然升高,将大量的液态和气态烃类赶进了相邻的事故泄放槽,迅速超过了其容量。由此造成的气相烃类云团最后被未知的火种所点燃。在邻近地区集中了大量的外来槽车运输工人,并且在装置显然已经超压、甚至气相已经排放到大气中时这些人也没有及时疏散,从而大大增加了死伤人数。