神经网络概述外文翻译Word格式.docx

神经网络概述外文翻译Word格式.docx

《神经网络概述外文翻译Word格式.docx》由会员分享，可在线阅读，更多相关《神经网络概述外文翻译Word格式.docx（12页珍藏版）》请在冰豆网上搜索。

●外文原文

NeuralNetworkIntroduction

1.Objectives

Asyoureadthesewordsyouareusingacomplexbiologicalneuralnetwork.Youhaveahighlyinterconnectedsetofsome1011neuronstofacilitateyourreading,breathing,motionandthinking.Eachofyourbiologicalneurons，arichassemblyoftissueandchemistry,hasthecomplexity,ifnotthespeed,ofamicroprocessor.Someofyourneuralstructurewaswithyouatbirth.Otherpartshavebeenestablishedbyexperience.

Scientistshaveonlyjustbeguntounderstandhowbiologicalneuralnetworksoperate.Itisgenerallyunderstoodthatallbiologicalneuralfunctions,includingmemory,arestoredintheneuronsandintheconnectionsbetweenthem.Learningisviewedastheestablishmentofnewconnectionsbetweenneuronsorthemodificationofexistingconnections.

Thisleadstothefollowingquestion:

Althoughwehaveonlyarudimentaryunderstandingofbiologicalneuralnetworks,isitpossibletoconstructasmallsetofsimpleartificial“neurons”andperhapstrainthemtoserveausefulfunction?

Theansweris“yes.”Thisbook,then,isaboutartificialneuralnetworks.

Theneuronsthatweconsiderherearenotbiological.Theyareextremelysimpleabstractionsofbiologicalneurons,realizedaselementsinaprogramorperhapsascircuitsmadeofsilicon.Networksoftheseartificialneuronsdonothaveafractionofthepowerofthehumanbrain,buttheycanbetrainedtoperformusefulfunctions.Thisbookisaboutsuchneurons,thenetworksthatcontainthemandtheirtraining.

2.History

Thehistoryofartificialneuralnetworksisfilledwithcolorful,creativeindividualsfrommanydifferentfields,manyofwhomstruggledfordecadestodevelopconceptsthatwenowtakeforgranted.Thishistoryhasbeendocumentedbyvariousauthors.OneparticularlyinterestingbookisNeurocomputing:

FoundationsofResearchbyJohnAndersonandEdwardRosenfeld.Theyhavecollectedandeditedasetofsome43papersofspecialhistoricalinterest.Eachpaperisprecededbyanintroductionthatputsthepaperinhistoricalperspective.

Historiesofsomeofthemainneuralnetworkcontributorsareincludedatthebeginningofvariouschaptersthroughoutthistextandwillnotberepeatedhere.However,itseemsappropriatetogiveabriefoverview,asampleofthemajordevelopments.

Atleasttwoingredientsarenecessaryfortheadvancementofatechnology:

conceptandimplementation.First,onemusthaveaconcept,awayofthinkingaboutatopic,someviewofitthatgivesclaritynottherebefore.Thismayinvolveasimpleidea,oritmaybemorespecificandincludeamathematicaldescription.Toillustratethispoint,considerthehistoryoftheheart.Itwasthoughttobe,atvarioustimes,thecenterofthesoulorasourceofheat.Inthe17thcenturymedicalpractitionersfinallybegantoviewtheheartasapump,andtheydesignedexperimentstostudyitspumpingaction.Theseexperimentsrevolutionizedourviewofthecirculatorysystem.Withoutthepumpconcept,anunderstandingoftheheartwasoutofgrasp.

Conceptsandtheiraccompanyingmathematicsarenotsufficientforatechnologytomatureunlessthereissomewaytoimplementthesystem.Forinstance,themathematicsnecessaryforthereconstructionofimagesfromcomputer-aidedtopography（CAT）scanswasknownmanyyearsbeforetheavailabilityofhigh-speedcomputersandefficientalgorithmsfinallymadeitpracticaltoimplementausefulCATsystem.

Thehistoryofneuralnetworkshasprogressedthroughbothconceptualinnovationsandimplementationdevelopments.Theseadvancements,however,seemtohaveoccurredinfitsandstartsratherthanbysteadyevolution.

Someofthebackgroundworkforthefieldofneuralnetworksoccurredinthelate19thandearly20thcenturies.Thisconsistedprimarilyofinterdisciplinaryworkinphysics,psychologyandneurophysiologybysuchscientistsasHermannvonHelmholtz,ErnstMuchandIvanPavlov.Thisearlyworkemphasizedgeneraltheoriesoflearning,vision,conditioning,etc.,anddidnotincludespecificmathematicalmodelsofneuronoperation.

Themodernviewofneuralnetworksbeganinthe1940swiththeworkofWarrenMcCullochandWalterPitts[McPi43],whoshowedthatnetworksofartificialneuronscould,inprinciple,computeanyarithmeticorlogicalfunction.Theirworkisoftenacknowledgedastheoriginofthe

neuralnetworkfield.

McCullochandPittswerefollowedbyDonaldHebb[Hebb49],whoproposedthatclassicalconditioning（asdiscoveredbyPavlov）ispresentbecauseofthepropertiesofindividualneurons.Heproposedamechanismforlearninginbiologicalneurons.

Thefirstpracticalapplicationofartificialneuralnetworkscameinthelate1950s,withtheinventionoftheperceptionnetworkandassociatedlearningrulebyFrankRosenblatt[Rose58].Rosenblattandhiscolleaguesbuilta