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1、附：外文翻译外文原文：FundamentalsofMechanicalDesignMechanicaldesignmeansthedesignofthingsandsystemsofamechanicalnature—machines,products,structures,devices,andinstruments.Forthemostpartmechanicaldesignutilizesmathematics,thematerialssciences,andtheengineering-mechanicssciences
2、.Thetotaldesignprocessisofinteresttous.Howdoesitbegin?Doestheengineersimplysitdownathisdeskwithablanksheetofpaper?And,ashejotsdownsomeideas,whathappensnext?Whatfactorsinfluenceorcontrolthedecisionswhichhavetobemade?Finally,then,howdoesthisdesignprocessend?Sometimes,b
3、utnotalways,designbeginswhenanengineerrecognizesaneedanddecidestodosomethingaboutit.Recognitionoftheneedandphrasingitinsomanywordsoftenconstituteahighlycreativeactbecausetheneedmaybeonlyavaguediscontent,afeelingofuneasiness,ofasensingthatsomethingisnotright.Theneedis
4、usuallynotevidentatall.Forexample,theneedtodosomethingaboutafood-packagingmachinemaybeindicatedbythenoiselevel,bythevariationsinpackageweight,andbyslightbutperceptiblevariationsinthequalityofthepackagingorwrap.Thereisadistinctdifferencebetweenthestatementoftheneedand
5、theidentificationoftheproblem.Whichfollowsthisstatement?Theproblemismorespecific.Iftheneedisforcleanerair,theproblemmightbethatofreducingthedustdischargefrompower-plantstacks,orreducingthequantityofirritantsfromautomotiveexhausts.Definitionoftheproblemmustincludeallt
6、hespecificationsforthethingthatistobedesigned.Thespecificationsaretheinputandoutputquantities,thecharacteristicsofthespacethethingmustoccupyandallthelimitationsonthesequantities.Wecanregardthethingtobedesignedassomethinginablackbox.Inthiscasewemustspecifytheinputsand
7、outputsoftheboxtogetherwiththeircharacteristicsandlimitations.Thespecificationsdefinethecost,thenumbertobemanufactured,theexpectedlife,therange,theoperatingtemperature,andthereliability.Therearemanyimpliedspecificationswhichresulteitherfromthedesigner'sparticularenvi
8、ronmentorfromthenatureoftheproblemitself.Themanufacturingprocesseswhichareavailable,togetherwiththefacilitiesofacertainplant,consti
