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1.
Inmodernuninterruptablepowersupplies ,in verterswith pulsewidthmodulation (PWM )con trolareusedtogeneratethesinusoidaloutputvolt age .Therequirementstoinvertersincludeahighstability ,highreliability ,fastdynamicresponseoveralltypesofloads,aswellasminimumtotalharmonicdistortion .Inthepast,openloopcontrolwithfeed for wardwereusedininverterstoproducethesinusoi dalwaveoutput ,whilearelativelyslowoutputvoltagermsfeedbackloopwereusedtoregulatethermsoftheoutputvoltage .Althoughthistypeofcontrolcould…  相似文献   

2.
Theclassiccableequationhasbeenusedtore presenttheexcitationoflongandstraightperipheral nervesinanelectricfield.Itpredictsthatexcitation occursnearthemaximumofthenegativefirstspa tialgradient-E'‖=- Ex/ xinthedirectionofan x axialfiber[1],whichisinagreem…  相似文献   

3.
Occlusivevasculardisorders,bothvenousandarterial,aresomeofthemostcommoncausesofmorbidityandmortalityindevelopedcountries.Theaimoftherapyinsuchconditionsis,firstly,torestoreandmaintainbloodflowtotheaffectedtissueororgan,andsecondly,torestorethesystemtothenormalhaemostaticstatewithoutovercompensatingandproducingcomplicationssuchashaemorrhage.Thrombolyticagents,suchasrecombinanttissueplasminogenactivator(rt-PA),arewidelyusedinthetreatmentofpatientswithacutemyocardialinfarction.However,successful…  相似文献   

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