单片机 外文翻译 外文文献 英文文献 基于单片机的超声波测距系统的研究与设计

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

2、netheaveragevalueofthewaveformsofFig.13.37.FIG.13.37Example13.13.Solutions:a.Byinspection,theareaabovetheaxisequalstheareabelowoveronecycle,resultinginanaveragevalueofzerovolts.b.UsingEq.(13.26):asshowninFig.13.38.51Inreality,thewaveformofFig.13.37(b)issimplythesquarewaveofFig.13.37(a)wit

3、hadcshiftof4V;thatisv2
=v1+4VEXAMPLE13.14Findtheaveragevaluesofthefollowingwaveformsoveronefullcycle:a.Fig.13.39.b.Fig.13.40.51Solutions:Wefoundtheareasunderthecurvesintheprecedingexamplebyusingasimplegeometricformula.Ifweshouldencounterasinewaveoranyotherunusualshape,however,wemustfindth

4、eareabysomeothermeans.Wecanobtainagoodapproximationoftheareabyattemptingtoreproducetheoriginalwaveshapeusinganumberofsmallrectanglesorotherfamiliarshapes,theareaofwhichwealreadyknowthroughsimplegeometricformulas.Forexample,theareaofthepositive(ornegative)pulseofasinewaveis2Am.Approximatin

5、gthiswaveformbytwotriangles(Fig.13.43),weobtain(usingarea
1/2baseheightfortheareaofatriangle)aroughideaoftheactualarea:Acloserapproximationmightbearectanglewithtwosimilartriangles(Fig.13.44):51whichiscertainlyclosetotheactualarea.Ifaninfinitenumberofformswereused,anexactanswerof2Amcouldb

6、eobtained.Forirregularwaveforms,thismethodcanbeespeciallyusefulifdatasuchastheaveragevaluearedesired.Theprocedureofcalculusthatgivestheexactsolution2Amisknownasintegration.Integrationispresentedhereonlytomakethemethodrecognizabletothereader;itisnotnecessarytobeproficientinitsusetocontinue

7、withthistext.Itisausefulmathematicaltool,however,andshouldbelearned.Findingtheareaunderthepositivepulseofasinewaveusingintegration,wehavewhere∫isthesignofintegration,0andparethelimitsofintegration,Amsinaisthefunctiontobeintegrated,anddaindicatesthatweareintegratingw