简介:Nanocarbonmaterialsplayacriticalroleinthedevelopmentofneworimprovedtechnologiesanddevicesforsustainableproductionanduseofrenewableenergy.Thisperspectivepaperdefinessomeofthetrendsandoutlooksinthisexcitingarea,withtheeffortofevidencingsomeofthepossibilitiesofferedfromthegrowinglevelofknowledge,astestifiedfromtheexponentiallyrisingnumberofpublications,andputtingbasesforamorerationaldesignofthesenanomaterials.Thebasicmembersofthenewcarbonfamilyarefullerene,graphene,andcarbonnanotube.Derivedfromthemarecarbonquantumdots,nanohorn,nanofiber,nanoribbon,nanocapsulate,nanocageandothernanomorphologies.Secondgenerationnanocarbonsarethosewhichhavebeenmodifiedbysurfacefunctionalizationordopingwithheteroatomstocreatespecifictailoredproperties.Thethirdgenerationofnanocarbonsisthenanoarchitecturedsupramolecularhybridsorcompositesofthefirstandsecondgenerationnanocarbons,orwithorganicorinorganicspecies.Theadvantagesofthenewcarbonmaterials,relatingtothefieldofsustainableenergy,arediscussed,evidencingtheuniquepropertiesthattheyofferfordevelopingnextgenerationsolardevicesandenergystoragesolutions.
简介:Thesystemofturbulentthermalconvectionisintroduced.Progressesinrecentdecadesinthefourmajorareasofresearchinturbulentconvectionarebriefyreviewed.Someoftherecenttrendsofthefeldarethendiscussed,whichalsoservetopointoutthatthefuturedirectionsinthisimportantfeldoffuidmechanicslieintheextensiontothenon-standardornon-classicalRayleigh–Bénardconfguration.
简介:Whenwetrytoestimatefutureenvironmentalcostsresultingfromourcurrenteconomicactivities,weusuallycalculatethepresentvalueoftheconsequencesforourfuturegenerationsbyutilizingadiscountrateasastandardeconomicprocedure.Thepopularityofthisprocedureissolelysupportedbyitssimplicitywhichassumes:(1)aperfectfinancialmarketovereven100years,and(2)existenceofastabletimepreferencebetweentwoconsecutiveperiodsforanindividualconsumer.Anapparentdeficiencyofthisapproachisthatthepresentvalueoflifequalityoffuturegenerationsvariestoalargeextentalonganarbitrarilychosendiscountrate.Asamatteroffact,thediscountrate,whichcouldreflectthetimepreferenceas2%or5%,matterswhenwepredictcurrentstrategiesofenvironmentalprotectionforfuturegenerations.Simplyapplyingadiscountratetoevaluatethequalityofourfuturegeneration,withoutclarifyingtheactualproductionmechanismbehindthis,isalmosttothesameasignoringthefactthatallofthegoodsareproducedthroughanactualproductionprocessandthatenvironmentaldegradationreducestheefficiencyofthatprocess.Thegreatestconcernforourfuturegenerationsshouldnotbegivenbyanassumeddiscountrate,sincethediscountrateitselfisdeterminedbyfinancialmarketconditionsatcertainpointsintime.