简介:TheserviceprovidedbytheGC(GammaCameras)intheNuclearMedicinedepartmentsfailsbecauseoftheirbreakdown,generallyduetotheassociatedelectronicsandnottothephysicaldetectioncomponents.Forthisreason,itwasdecidedtodevelopanelectronicsystemthatallowstherecoveryandoptimizationofdisusedGC,startingwiththedesignofthepreamplifierforaPMT(photomultipliertube).Thecircuitwasdesignedandsimulatedandthelistofcomponentsnecessaryfortheconstructionofthepreamplifierwasgenerated,aswellastheprintedcircuitboardwasdesignedforitsassembly.Bysimulatingthepreamplifierthisworkedinlinearmode.Thisdeterminesthattheamplitudeoftheoutputsignalisproportionaltotheamountofchargedeliveredbythedetector.ThiscardallowsanautomaticadjustmentofthesignalsofthePMTasdothemodernGC.
简介:HaveYouGotYourChinese"GreenCard"!¥LAOFUAnewlandofopportunity,orsimplyaquietspotfromwhichonecansitandwatchtherestoftheworldgoby...
简介:Twosignaturesystemsbasedonsmartcardsandfingerprintfeaturesareproposed.Inonesignaturesystem,thecryptographickeyisstoredinthesmartcardandisonlyaccessiblewhenthesigner'sextractedfingerprintfeaturesmatchhisstoredtemplate.Toresistbeingtamperedonpublicchannel,theuser'smessageandthesignedmessageareencryptedbythesigner'spublickeyandtheuser'spublickey,respectively.Intheothersignaturesystem,thekeysaregeneratedbycombiningthesigner'sfingerprintfeatures,checkbits,andarememberablekey,andtherearenomatchingprocessandkeysstoredonthesmartcard.Additionally,thereisgenerallymorethanonepublickeyinthissystem,thatis,thereexistsomepseudopublickeysexceptarealone.