基于单片机的超声波测距系统的研究与设计外文翻译

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1、附录附录A外文翻译theequivalentdcvalue.Intheanalysisofelectroniccircuitstobeconsideredinalatercourse,bothdcandacsourcesofvoltagewillbeappliedtothesamenetwork.Itwillthenbenecessarytoknowordeterminethedc(oraveragevalue)andaccomponentsofthevoltageorcurrentinvariouspartsofthesystem.EXAMPLE13.13Dete

2、rminetheaveragevalueofthewaveformsofFig.13.37.FIG.13.37Example13.13.Solutions:a.Byinspection,theareaabovetheaxisequalstheareabelowoveronecycle,resultinginanaveragevalueofzerovolts.b.UsingEq.(13.26):asshowninFig.13.38.Inreality,thewaveformofFig.13.37(b)issimplythesquarewaveofFig.13.37(a

3、)withadcshiftof4V;thatisv2
=v1+4VEXAMPLE13.14Findtheaveragevaluesofthefollowingwaveformsoveronefullcycle:a.Fig.13.39.b.Fig.13.40.Solutions:Wefoundtheareasunderthecurvesintheprecedingexamplebyusingasimplegeometricformula.Ifweshouldencounterasinewaveoranyotherunusualshape,however,wemustf

4、indtheareabysomeothermeans.Wecanobtainagoodapproximationoftheareabyattemptingtoreproducetheoriginalwaveshapeusinganumberofsmallrectanglesorotherfamiliarshapes,theareaofwhichwealreadyknowthroughsimplegeometricformulas.Forexample,theareaofthepositive(ornegative)pulseofasinewaveis2Am.Appr

5、oximatingthiswaveformbytwotriangles(Fig.13.43),weobtain(usingarea
1/2baseheightfortheareaofatriangle)aroughideaoftheactualarea:Acloserapproximationmightbearectanglewithtwosimilartriangles(Fig.13.44):whichiscertainlyclosetotheactualarea.Ifaninfinitenumberofformswereused,anexactanswerof

6、2Amcouldbeobtained.Forirregularwaveforms,thismethodcanbeespeciallyusefulifdatasuchastheaveragevaluearedesired.Theprocedureofcalculusthatgivestheexactsolution2Amisknownasintegration.Integrationispresentedhereonlytomakethemethodrecognizabletothereader;itisnotnecessarytobeproficientinitsu

7、setocontinuewiththistext.Itisausefulmathematicaltool,however,andshouldbelearned.Findingtheareaunderthepositivepulseofasinewaveusingintegration,wehavewhere∫isthesignofintegration,0andparethelimitsofintegration,Amsinaisthefunctiontobeintegrated,anddaindicatesthatweareintegratingwithres