简介:Thefluorineionsensitivefield-effecttransistor(F--ISFET)ismadebydepositingverythinLaF3filmongridoffield-effecttransistorwithsputtermethod.Theoperatingprinciple,measuringmethodandmeasuredresultsofF--ISFETaregiven.Themeasuredresultsshowthatthiskindofsensorhashighersensitivity,shorterresponsetimeandbetterlinearity.Onthebasisofexperimentalresults,thefactorofinfluencingthesteadinessandrepeatabilityofF--ISFETareconjectured.
简介:Modernnetworksystemshavemuchtroubleinsecurityvulnerabilitiessuchasbufferoverflow,bugsinMicrosoftInternet,sensornetworkroutingprotocoltoosimple,securityflawsofapplications,andoperatingsystems.Moreover,wirelessdevicessuchassmartphones,personaldigitalassistants(PDAs),andsensorshavebecomeeconomicallyfeasiblebecauseoftechnologicaladvancesinwirelesscommunicationandmanufacturingofsmallandlow-costsensors.Therearetypologiesofvulnerabilitiestobeexploitedinthesedevices.Inordertoimprovesecurities,manymechanismsareadopted,includingauthentication,cryptography,accesscontrol,andintrusiondetectionsystems(IDS).Ingeneral,intrusiondetectiontechniquescanbecategorizedintotwogroups:misusedetectionandanomalydetection.Themisusedetectionsystemsusepatternsofwell-knownattacksorweakspotsofthesystemstoidentifyintrusions.Theweaknessofmisusedetectionsystemsisunabletodetectanyfuture(unknown)intrusionuntilcorrespondingattacksignaturesareintrudedintothesignaturedatabase.Anomalydetectionmethodstrytodeterminewhetherthedeviationisfromtheestablishednormalusagepatternsornot.Thecriticalsuccessofanomalydetectionreliesonthemodelofnormalbehaviors.
简介:Inthisdissertation,sereralkeyproblemsinthefieldofsteganographicimagesecurityaremainlystudiedanddiscussed:(1)Anovelkindofimagecryptosystemisstudied.Theencryptedinformationofsecretimageisembeddedintoanordinaryimage,whichcanbetransmittedpublicly,anditwillnotcauseattentionofillegaleavesdropper.Thefollowingresultsareachieved:(a)Theimagehidingalgorithmanditsimprovedalgorithmbasedonwavelettransformandvectorquantizationareproposed,andbothalgorithmsembedthesecretimageaftertakingfulladvantageofwavelettransform(WT)tocompressit.(b)IntroducingtheCDMAconceptincommunicationtheory,anovelkindofimagecryptosystem—imagehidingcryptosystemofimagedivisionmultipleaccessisproposed.Weencryptkeyinformationofseveralsecretimagesandthenhidethemintoanimage,whichisanordinaryimage.Afterreceiversgettheimage,eachreceivercanrestorecorrespondingsecretimageindependently.Comparedwithotherimageencryptionalgorithms,ournewimagehidingcryptosystemcancompresssecretimagedataefficiently.Moreover,thesecurityandpracticabilityofoursystemisbetter.(2)Digitalwatermarkingisthemostimportantbranchofinformationhiding,whichhasbeenthehotspotofinternationalacademia.Digitalwatermarkinghasbeenproposedasasolutiontotheproblemofcopyrightprotectionofmultimediadocumentsinnetworkedenvironments.Inthisfield,thefollowingresultsareachieved:(a)AnewfrequencyinformationhidingandwatermarkingalgorithmbasedonWTandDiscreteCosineTransform(DCT)ispresented.AftercompressedbyWT,theinformationofsecretimageisembeddedintoDCTdomain.ThealgorithmhasgoodimperceptibilityandsecurityandisrobustagainstJPEGcompressingandcropping.Thealgorithmcanbeusedtoembedwatermarkintoimages,andthewatermarkmaybeone256-colorpictureormoreandmorethanonesecretimagecanbehiddenintoasinglecarrierimage.(b)Anovelwatermarkingalg
简介:Thispapermainlydiscussesthe"double-trackcharge"system(priceprejudicechargesystem)intheoryandpractice.Theauthorexplainsandanalyzesthe"differentialchargesphenomenon"ofuniversitiesinChinabytaking"Paretooptimality"asregulationstandardand"Darwinoptimality"asempiricalstandard,combiningregulationstandardwithpracticestandard,realisticstandardofvaluejudgmentwithultimatestandard,andfairnesswithefficiency.Thispaperprovidestheoreticalreferenceandanoperationplatformforapplicationandimplementationdifferentialchargesandthecontainmentofcorruptionincollegeenrollment.
简介:ThispaperstartswiththediscussionoftheprincipleofReduced-Rank(RR)Space-TimeAdaptiveProcessing(STAP).Itisfollowedbyadedicationoftheupperboundperformanceofalleigen-basedRRmethodsprovidedbyCrossSpectralMethod(CSM)undertheconditionofagivenprocessorrankandanidenticalsecondarysamplesize.AperformancecomparisonbetweentwoRRSTAPprocessorswithprefixedstructureandCSMisperformedbythemeansofsimulations.Itisshownthattheperformanceoftimepre-filteringfollowedbyjointlylocalizedSTAPstructure(i.e.3DT-SAP)isveryclosetotheupperboundandtherebyitisaneffectiveRRapproach.
简介:Greysequencegenerationcandrawoutanddevelopimpliedrulesoftheoriginaldata.Differentkindsofgenerationmethodsweresummarizedandclassifiedintotwotypes:partialgenerationandwholegeneration.Theaveragegenerationandstepwiseratiogenerationisdisussed,thepreferencegenerationisregardasaspecialcaseofproportionaldivisionbasedonanalysisgeometrictheory,proposeanideaofusingconcaveandconvexstatusofdiscretedatatodeterminethegenerationcoefficient.Basedonthestepwiseandsmoothratiogeneration,atendencyaveragegenerationisproposedandhaveacomparisonusingthedataprovidedinpaperslistedinthereferences.Thecomparisonprovesthatthenewgenerationisbetterthantheothertwogenerationsanderrorsareobviouslyreduced.
简介:Anin-depthexplorationhasbeenmadeoftelecommunicationtariffanditsdecisionsupportsystem.Itisthefirstattempttoconductsuchastudybytheintegrateduseofeconometrics,systememulationandsystemdynamics.Apractically-demandedcostmodelofthetelecommunicationtariffdecisionisproposed.Thesystemhasbeenverifiedwithrealdata.
简介:ThemathematicalmodelofspaceborneSARsystemsanditscomputersimulationsaredescribed.Resultsofcomputersimulationsaboutrangemigration,rangemigrationcorrection,azimuthweightingandsignalgeneration/processingaregiven.ThissoftwarecanbeusedtosimulatethedynamicprocessesinspaceborneSARsystems,todevelopnewsignalprocessingtechniquesandtoevaluatetheperformanceofthedesignedsystem.
简介:Thewavelettransformhasremarkableadvantagesandwideapplicationsindenoisingbecauseofitscharacteristicofgoodtime-frequency.Basedontheanalysisoftraditionalwaveletdenoisingmethods,whicharebasedonFouriertransform,animprovedmethodisproposed.ItovercomestheshortcomingsofthetraditionalFourierdenoisingmethod.Inthispaper,thedenoisingproceduresareintroducedrespectivelybasedonthewavelettransformandthemethodofconnectingthewaveletthresholdwiththewaveletbasisisadopted.ThroughMatlabsimulationandconcretedata,itarrivesattheconclusionthatthemethodofsignaldenoisingbasedonthewavelettransformisobviouslymoreeffectiveandbetterthanthetraditionalmethodbasedonFouriertransform.
简介:Anovelellipsoidalhelicalantennaisproposedandstudiedinthisletter.Asaspecialin-stance,thehemisphericalhelicalantennasareanalyzedfirstly,whichindicatesthatthecharacteristicsofatwo-armunitarebetterthanthatofasingle-armunit.Basedonthis,theellipsoidalhelicalantenna,formedbychangingtheaxialdirection’sdimensionofthetwo-armhemisphericalhelicalantenna,isanalyzedbythemomentmethodwithcurvedbasicandtestingfunction.TheeffectstoVSWR(VoltageStandingWaveRatio),gain,polarizationandpatternsbytheaxialdirection’sdimensionsareinves-tigated.Thestudyresultsprovidedependablegisttothechoiceofantennaformataccordingtothepracticalrequirements.
简介:Whenthereturnscomefromtwoormoreunresolvedtargets(thesignalsarenotresolvedinthefrequencyortimedomains)inamonopulseradarsystem,thedirection-of-arrival(DOA)estimateindicatedbythemonopulseratioisnotthetrueinformationofthetrackedtarget.Thenthetrackingsystemsisinfluenced.Anapproachhasbeenproposedtodetectwhetherthereturnscomefromasingletargetortwounresolvedtargets.Theaboveapproachisextendedfromtwotothreeunresolvedtargets.Thesimulationindicatesthatthedetectionprobabilityunderthethreeunresolvedtargetsisnotsuretoexceedthedetectionprobabilityunderthetwounresolvedtargets.
简介:Thepricingoftelecommunicationservicesisquiteimportantaswellascomplicated.ThispaperstrengthenstheresearchoftheoriesandimplementationoftelecommunicationtariffinChina.Itishelpfulforthegovernmentauthoritiesandenterprisestounifyandstandardizetheregulatorymethods,toguidethedecidingofthestructureandleveloftelecommunicationtariffbyimplementingscientifictheories,tofurtherdevelopandoptimizethetariffsystem.Thispaperconductsasystematic,in-depthandcreativeresearchonsomeofthemostpopularandmostdifficultproblemsintheareaoftelecommunicationtariffresearch,suchastheregulationoftelecommunicationtariff,thetheoriesoftelecommunicationtariff,thesystematicpricingtheory,theinterconnectioncharge,themodelcostevaluationtheory,thelong-runincrementalcosttheory,andtheinternationaltelecommunicationtariff.Afterstudyingtheforeignmethodsontelecommunicationtariffregulation,basingonthecurrentsituationofChina'stariffregulation,thescopeandmethodsforChina'stelecommunicationtariffregulationaresuggested.Aimedattheweaknessofpricingtheoryforenterprisestosetuptelecommunicationtariffs,anoverallframeworkoftelecommunicationtarifftheoriesisproposed.Thesystematicpricingtheoryandmodelcostevaluationtheoryoftelecommunicationservicesareputforwardfromabrandnewperspective.Afronttopic,theLRICtheory,isprobed.Inaddition,thepricingpracticesofnetworkinterconnectionchargeandinternationaltelecommunicationtariff,whicharecurrentlyveryattractivetothetheorists,arediscussed.Basingonthesestudies,thispaperimprovesthestructureoftelecommunicationtarifftheory.ItprovidestheChinesegovernmentauthoritieswithpracticalmethodsandhelpfulsupportstoregulatethetelecommunicationtariffs;inthemeantime,italsoprovidestheenterpriseswithscientificpricingtheoriesandmethodstosetuptelecommunicationtariffs.Overall,thispaperhasnot
简介:ZnTe/ZnTe∶Culayerisusedasacomplexbackcontact.TheparametersofCdTesolarcellswithandwithoutthecomplexbackcontactsarecompared.Theeffectsofun-dopedlayerthickness,dopedconcentrationandpost-depositionannealingtemperatureofthecomplexlayeronsolarcellsperformanceareinvestigated.TheresultsshowthatZnTe/ZnTe∶CulayercanimprovebackcontactsandlargelyincreasetheconversionefficiencyofCdTesolarcells.Un-dopedlayerandpost-depositionannealingofhightemperaturecanincreaseopenvoltage.Usingthecomplexbackcontact,asmallCdTecellwithfillfactorof73.14%andconversionefficiencyof12.93%isobtained.
简介:ThelowresistancePTCceramicthermistormaterialwithexcellenteleectricalpropertiesaresuccessfullyfabricatedbyrawmaterialsatindustrialrangemadeinourcountryonthestudyofitscompositionexpressionandfabricationprocessbyusingtheadditionofNb,La,Y,Ta,microstructureregulatorBNandASTLphase.Thecompositionanditsfabricationmethodarestudied.TherelationofelectricalpropertiesofthePTCceramicmaterialtoitscompositionexpressionanditsrelatedelectricalpropertiesarediscussed.
简介:Differenceexpansion(DE)isoneofthefamousschemesinthefieldofreversibledatahiding.Withthehighefficiencyandsimplicity,DEalsohasreceivedmoreattentionovertheyears.DEhasagoodinformationcapacity,butduetoitsmajorlocationmap,thepurepayloadisratherlow.Thereforemanyscholarsdidrelevantimprovementswhichletnpixelsasaunitinsteadoftheoriginaltwopixelsasaunitandcanadaptivelyadjustthenumberofembeddingsecretinformationaccordingtothesmoothnessdegreeoftheblock,whichachievestheresultofimprovingtheinformationpayloadortheimagequality.Inthispaper,thestudyofDE-basedreversibledatahidingschemesiscomprehensivelydiscussed.TheperformanceofDEbasedschemesisevaluatedandcomparedintermsofembeddingcapacityandstego-imagequality.
简介:Inthispaper,anewpseudocolormethodtodisplaysoundholospectrogramisproposedandstudied.Onthepictureofsuchafour-dimensionalspectrogram,thehorizontalaxisreferstotime,theverticalaxistofrequency,thecolortophase,andthebrightnesstomagnitude.Anexampleofdisplayisgivenbyemployingtherealizedsystem.
简介:Fromaneconomicangle,thispaperanalyzesanddemonstratestheirrationalityofthecurrentInternetsettlementofInterconnection;thenpointsoutthattheheavychargesforInternetinterconnectionfromdevelopingcountriestothedevelopedcountrycanbethoughtofasoneofthemainandkeyreasonsthatrestrictthebalanceddevelopmentoftheInternetintheworld,whichcausestheintensificationof'digitaldivide',widensthegapbetweenpoorandrichcountriesandfurtheraggravatesthedisequilibriumoftheglobaleconomicdevelopment;andthustheconclusionisreached:thepublicpolicyselectionshouldbemadebythewholeinternationalsocietyjointlyforpayingcloseattentionandregulatingsettlementsystemsofInternetinterconnectiontodwindle'digitaldivide'throughouttheworld.
简介:Amethod,whichcanpredictthevalencebandoffsetsatstrainedlayerheterojunctionsunderdifferentstrainsituationsonlybycalculatingbandstructuresanddeformationparametersofthebulkmaterials,issuggested.Theapplicabilityofthismethodisverifiedbycalculationofthevalencebandoffsetsatstrainedlayerheterojuntions,suchasInP/InAs,InP/GaP,GaAs/InAs,GaP/GaAsandAlAs/InAswithvariousstrainconditions.