英语长篇阅读文章.docx
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英语长篇阅读文章
英语长篇阅读文章
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英语长篇阅读文章1
科技与自然
Technologythatimitatesnature
Biomimetics:
Engineersareincreasinglytakingaleafoutofnaturesbookwhenlookingforsolutionstodesignproblems
AFTERtakinghisdogforawalkonedayintheearly1940s,GeorgedeMestral,aSwissinventor,becamecuriousabouttheseedsoftheburdockplantthathadattachedthemselvestohisclothesandtothedogsfur.Underamicroscope,helookedcloselyatthehook-and-loopsystemthattheseedshaveevolvedtohitchhikeonpassinganimalsandaidpollination,andherealisedthatthesameapproachcouldbeusedtojoinotherthingstogether.TheresultwasVelcraproductthatwasarguablymorethanthreebillionyearsinthemaking,sincethatishowlongthenaturalmechanismthatinspiredittooktoevolve.
Velcroisprobablythemostfamousandcertainlythemostsuccessfulexampleofbiologicalmimicry,orbiomimetics.Infieldsfromroboticstomaterialsscience,technologistsareincreasinglyborrowingideasfromnature,andwithgoodreason:
naturesdesignshave,bydefinition,stoodthetestoftime,soitwouldbefoolishtoignorethem.Yettransplantingnaturaldesignsintoman-madetechnologiesisstillahit-or-missaffair.
Engineersdependonbiologiststodiscoverinterestingmechanismsforthemtoexploit,saysJulianVincent,thedirectoroftheCentreforBiomimeticandNaturalTechnologiesattheUniversityofBathinEngland.Soheandhiscolleagueshavebeenworkingonaschemetoenableengineerstobypassthebiologistsandtapintonaturesingenuitydirectly,viaadatabaseofbiologicalpatents.Theideaisthatthisdatabasewillletanyonesearchthroughawiderangeofbiologicalmechanismsandpropertiestofindnaturalsolutionstotechnologicalproblems.
Hownottoreinventthewheel
Surelyhumanintellect,andthedeliberateapplicationofdesignknowledge,candevisebettermechanismsthanthemindless,randomprocessofevolution?
Farfromit.Overbillionsofyearsoftrialanderror,naturehasdevisedeffectivesolutionstoallsortsofcomplicatedreal-worldproblems.Taketheslipperytaskofcontrollingasubmersiblevehicle,forexample.Usingpropellers,itisincrediblydifficulttomakerefinedmovements.ButNektonResearch,acompanybasedinDurham,NorthCarolina,hasdevelopedarobotfishcalledMadeleinethatmanoeuvresusingfinsinstead.
Insomecases,engineerscanspenddecadesinventingandperfectinganewtechnology,onlytodiscoverthatnaturebeatthemtoit.TheVenusflowerbasket,forexample,akindofdeep-seasponge,hasspinyskeletaloutgrowthsthatareremarkablysimilar,bothinappearanceandopticalproperties,tocommercialopticalfibres,notesJoannaAizenberg,aresearcheratLucentTechnologysBellLaboratoriesinNewJersey.Andsometimesthesystemsfoundinnaturecanmakeeventhemostadvancedtechnologieslookprimitivebycomparison,shesays.
Theskeletonsofbrittlestars,whichareseacreaturesrelatedtostarfishandseaurchins,containthousandsoftinylensesthatcollectivelyformasingle,distributedeye.Thisenablesbrittlestarstoescapepredatorsanddistinguishbetweennightandday.Besideshavingunusualopticalpropertiesandbeingverysmalleachisjustone-twentiethofamillimetreindiameterthelenseshaveanothertrickofparticularrelevancetomicro-opticalsystems.Althoughthelensesarefixedinshape,theyareconnectedviaanetworkoffluid-filledchannels,containingalight-absorbingpigment.Thecreaturecanvarythecontrastofthelensesbycontrollingthisfluid.Thesameideacanbeappliedinman-madelenses,saysDrAizenberg.Thesearemadefromsiliconandsocannotchangetheirproperties,shesays.Butbycopyingthebrittlestarsfluidicsystem,shehasbeenabletomakebiomimeticlensarrayswiththesameflexibility.
Anotherdemonstrationofthepowerofbiomimeticscomesfromthegecko.Thislizardsabilitytowalkupwallsandalongceilingsisofmuchinterest,andnotonlytofansofSpider-Man.Twogroupsofresearchers,oneledbyAndreGeimatManchesterUniversityandtheotherbyRonFearingattheUniversityofCalifornia,Berkeley,haveindependentlydevelopedwaystocopythegeckosabilitytoclingtowalls.Thesecretofthegeckossuccessliesinthetinyhair-likestructures,calledsetae,thatcoveritsfeet.Insteadofsecretingastickysubstance,asyoumightexpect,theyowetheiradhesivepropertiestoincrediblyweakintermolecularattractiveforces.ThesevanderWaalsforces,astheyareknown,whichexistbetweenanytwoadjacentobjects,arisebetweenthesetaeandthewalltowhichthegeckoisclinging.Normallysuchforcesarenegligible,butthesetae,withtheirspatula-liketips,maximisethesurfaceareaincontactwiththewall.Theweakforces,multipliedacrossthousandsofsetae,arethensufficienttoholdthelizardsweight.
BoththeBritishandAmericanteamshaveshownthattheintricatedesignofthesemicroscopicsetaecanbereproducedusingsyntheticmaterials.DrGeimcallstheresultgeckotape.Thetechnologyisstillsomeyearsawayfromcommercialisation,saysThomasKennyofStanfordUniversity,whoisamemberofDrFearingsgroup.Butwhenitdoesreachthemarket,ratherthanbeingusedtomakewall-crawlinggloves,itwillprobablybeusedasanalternativetoVelcro,orinstickingplasters.Indeed,saysDrKenny,itcouldbeparticularlyusefulinmedicalapplicationswherechemicaladhesivescannotbeused.
Whileitisfarfromobviousthatgeckosfeetcouldinspireanewkindofstickingplaster,therearesomefieldssuchasroboticsinwhichborrowingdesignsfromnatureisself-evidentlythesensiblethingtodo.ThenextgenerationofplanetaryexplorationvehiclesbeingdesignedbyAmericasspaceagency,NASA,forexample,willhavelegsratherthanwheels.Thatisbecauselegscangetyouplacesthatwheelscannot,saysDrKenny.Wheelsworkwellonflatsurfaces,butaremuchlessefficientonuneventerrain.ScientistsatNASAsAmesResearchCentreinMountainView,California,areevaluatinganeight-leggedwalkingrobotmodelledonascorpion,andAmericasDefenceAdvancedResearchProjectsAgency(DARPA)isfundingresearchintofour-leggedrobotdogs,withaviewtoapplyingthetechnologyonthebattlefield.
Havinglegsisonlyhalfthestoryitshowyoucontrolthemthatcounts,saysJosephAyers,abiologistandneurophysiologistatNortheasternUniversity,Massachusetts.Hehasspentrecentyearsdevelopingabiomimeticroboticlobsterthatdoesnotjustlooklikealobsterbutactuallyemulatespartsofalobstersnervoussystemtocontrolitswalkingbehaviour.Thecontrolsystemofthescorpionrobot,whichisbeingdevelopedbyNASAinconjunctionwiththeUniversityofBremeninGermany,isalsobiologicallyinspired.Meanwhile,aFinnishtechnologyfirm,Plustech,hasdevelopedasix-leggedtractorforuseinforestry.Clamberingoverfallenlogsandupsteephills,itcancrossterrainthatwouldbeimpassableinawheeledvehicle.
Otherexamplesofbiomimeticsabound:
Autotype,amaterialsfirm,hasdevelopedaplasticfilmbasedonthecomplexmicrostructuresfoundinmotheyes,whichhaveevolvedtocollectasmuchlightaspossiblewithoutreflection.Whenappliedtothescreenofamobilephone,thefilmreducesreflectionsandimprovesreadability,andimprovesbatterylifesincethereislessneedtoilluminatethescreen.ResearchersattheUniversityofFlorida,meanwhile,havedevisedacoatinginspiredbytherough,bristlyskinofsharks.Itcanbeappliedtothehullsofshipsandsubmarinestopreventalgaeandbarnaclesfromattachingthemselves.AtPennStateUniversity,engineershavedesignedaircraftwingsthatcanchangeshapeindifferentphasesofflight,justasbirdswingsdo.AndDrVincenthasdevisedasmartfabric,inspiredbythewayinwhichpineconesopenandclosedependingonthehumidity,thatcouldbeusedtomakeclothingthatadjuststochangingbodytemperaturesandkeepsthewearercool.
Fromhit-and-misstopoint-and-click
Yetdespiteallthesesuccesses,biomimeticsstilldependsfartooheavilyonserendipity,saysDrVincent.Heestimatesthatthereisonlya10%overlapbetweenbiologicalandtechnologicalmechanismsusedtosolveparticularproblems.Inotherwords,thereisstillanenormousnumberofpotentiallyusefulmechanismsthathaveyettobeexploited.Theproblemisthattheengineerslookingforsolutionsdependonbiologistshavingalreadyfoundthemandthetwogroupsmoveindifferentcirclesandspeakverydifferentlanguages.Anaturalmechanismorpropertymustfirstbediscoveredbybiologists,describedintechnologicalterms,andthenpickedupbyanengineerwhorecognisesitspotential.
Thisprocessisentirelythewrongwayround,saysDrVincent.Tobeeffective,biomimeticsshouldbeprovidingexamplesofsuitabletechnologiesfrombiologywhichfulfiltherequirementsofaparticularengineeringproblem,heexplains.Thatiswhyheandhiscolleagues,withfundingfromBritainsEngineeringandPhysicalSciencesResearchCouncil,havespentthepastthreeyearsbuildingadatabaseofbiologicaltrickswhichengineerswillbeabletoaccesstofindnaturalsolutionstotheirdesignproblems.Asearchofthedatabasewiththekeywordpropulsion,forexample,producesarangeofpropulsionmechanismsusedbyjellyfish,frogsandcrustaceans.
ThedatabasecanalsobequeriedusingatechniquedevelopedinRussia,knownasthetheoryofinventiveproblemsolving,orTRIZ.Inessence,thisisasetofrulesthatbreaksdownaproblemintosmallerparts,andthosepartsintoparticularfunctionsthatmustbeperformedb