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1、SmallisbeautifulManandMachineWhileitmaybetruethatsmallisbeautiful,functiondoesnotalwaysstayunchangedwhendimensionsarereduced.Thisisparticularlytrueaboutheatengines,likethesteamengineorthepetrolengine.Theseenginesworkbecauseoftheforceofmoleculesofahotgasandthesystembreaksdownwhe
2、nthemovingpartsarereducedtoasizecomparablewiththemovementspanofmolecules.Yet,agroupofresearchersattheUniversityofStuttgartandtheMax-PlanckInstituteforIntelligentSystems,inthesamecity,astheyreportinthejournal,Nature,havefoundthataheatengineofthesizeofmicronsisabletoworkandmaysho
3、wthewayforenergy-efficientmachinesatthesedimensions.TheheatengineThisisadevicethatchangesheatenergyintomechanicalenergy.Theearliestinstancesusedsteamgeneratedbyboilingwatertoblowthings,intheplaceofwindandthesimplestdevelopmentsweremechanismsthatcouldonlypumpwater,notversatileme
4、thodstoworkdifferentkindsofmachinery.Theearlysteamenginesthatcoulddothischangedthefaceofindustry,whichcouldnowbelocatedawayfromflowingwaterasasourceofmotivepowerandbroughtintheindustrialrevolution.Whilethesteamengineusesheatfromoutsidetheengine,toheatthesteam,thepetrolordiesele
5、nginesare‘internalcombustion’engines.Itisthefuelitselfthatpushesthepistonsandmakesthemotorgo.Butsteamenginescanuseanykindoffuelandarealsoabletoworkathighaltitudes,whereotherengineshaveissues.TheprincipleoftheheatengineisnicelydescribedintheStirlingengine,whichwasdevelopedasanai
6、rengineintheyear1816,asanimprovementoverthesteamengine.TheStirlingenginehastwocylinders,onewherethegasisheatedandpushesthepistontoturnaflywheelandtheother,whichiscooledsothatthepistonmovesback,whilefeedingtheworkingsubstancegasbackintotheothercylinder,tobeheated.Thecomplementar
7、ymotionofthetwopistonsworkstheflywheel,whichcanbeconnectedtoothermachinery,amill,apowerloomoralocomotivewheel.Theprincipleisthatwhenthefirstcylinderisheated,thegasmoleculesstartmovingfasterandpushhardagainstthepiston,whichmovestheflywheel.Thisalsocausesthegastoexpand,whichcools
8、thegas.Infact,itisinthiscoolingthattheheatenergythatwa
