本站原创托福阅读纯英语论文文献3
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Fuel-singtyres
Hysterectomy
Silicaextractedfromricehuskakeorgreenertyres
TYRESareremarkablepiecesofengineering.Athighspeedinslipperybendstheyprovideonlyafewsquarecentimetresofcontactwiththeroad,yettheyhelpadriversteersafelyaroundthecorner.Once,theyweremadeentirelyofnaturalrubber.Thesedaystheyalsocontainrubber-likepolymers,layersofsteelbraidingandtextilereinforcements,allofwhichimproveperformanceandcutfuelconsumption.NowPirelli,anItaliantyremaker,ianufacturingfuel-singtyresthataregreenerstillbyextractingoneoftheiringredientromricehusks.
Onegoodwaytosefuelistoreducerollingresistance,whichiscaused,inpart,byehicle'sweightrepeatedlysquashingitstyres.Asthetyresbouncetheyconvertkiicenergyintoheat,thuswastingit.Hysteresisloss,asthisisknown,canbereducedbymixingatyre'srubberwithpowderedmaterialthathasstrongchemicalbondsinit.
Inthepast,thematerialofchoicehasbeencarbonblack,asootysubstancemadebytheinpletebustionofpetroleumproducts.Morerecently,silica(silicondioxide,whicheromsand)hasetotheforefront.Silicaisbetterbecauseitlowershysteresislosswithoutreducingatyre'sgrip.Itthuscutsrollingresistancebyaround30%,paredwithitspredecessor.Thattranslatesintoa5-7%reductioninfuelconsumption.Andsilicaalsoincreasesatyre'swetgrip.
Brazilbouncesback
Sandischeap.Butprocessingitintosomethingsuitableforuseintyresrequireseffortandmoney.Soifnatureweretoprovidegrainsofsilicasuitableforusewithoutprocessing,thatwouldbeabonus.Andnaturedoes.Grassescontaintinypiecesofsilica,calledphytoliths(illustratedabove),whosejobistodiscourageherbivores,bothvertebrateandinsect.Pirelli'sengineersrealisedthatthesedefensiveweaponsaretheidealsizetoaddtotyresinordertocontrolhysteresisloss,andthatareadysupplyofthemisailableinthehusksleftoverfromthemillingofrice.
Ricehuskswereoncewaste.Thesedaystheyhesomevaluebecausetheyareusedauelinall-scaleelectricitygenerators.ButfromPirelli'spointofview,thatisagoodthing,becausewhatthefirmisinterestedinisthephytolithsleftbehindintheash—anduntilnowtheashitselfreallywaswaste.ThefirmhassetupafactoryinMeleiro,atowninarice-growingareaofsouthernBrazil,toextractphytolithsandputthemintyres.Theasheromricehusksburnedtohelppowerthefactory.
Atonneofriceproducesaround200kgofhusksandthose,inturn,yield40kgofsilica.AccordingtoDanieleLorenzetti,whoisinchargeoftheproject,by2016thefactorywillbeprovidingnearlyathirdofthesilicaPirellineedorthe400,000tonnesoftyresitmakesinBrazil.
Thetechnologycouldspreadfast,especiallyinotherrice-growingareas.ForBraziliansthatwouldheadeliciousirony.TheAmazonrainforestwastheoriginalhomeofrubbertrees,butBrazil'srubberindustrywasdevastatedwhenseedsuggledtoAsiawereusedtosetuprivalplantations.BytakinganAsiancropandusingittomakebettertyres,theywillbegettingtheirownback.
来源于:小马过河
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