学科分类
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79 个结果
  • 简介:Thefluorineionsensitivefield-effecttransistor(F--ISFET)ismadebydepositingverythinLaF3filmongridoffield-effecttransistorwithsputtermethod.Theoperatingprinciple,measuringmethodandmeasuredresultsofF--ISFETaregiven.Themeasuredresultsshowthatthiskindofsensorhashighersensitivity,shorterresponsetimeandbetterlinearity.Onthebasisofexperimentalresults,thefactorofinfluencingthesteadinessandrepeatabilityofF--ISFETareconjectured.

  • 标签: FIELD-EFFECT transistor(FET) FLUORINE ion sensitive-FET Insulated
  • 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.

  • 标签: 入侵检测系统 异常检测方法 传感器网络 安全漏洞 个人数字助理 误用检测
  • 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

  • 标签: 智能安全 密码 图像 知识产权保护
  • 简介:Thispapermainlydiscussesthe"double-trackcharge"system(priceprejudicechargesystem)intheoryandpractice.Theauthorexplainsandanalyzesthe"differentialchargesphenomenon"ofuniversitiesinChinabytaking"Paretooptimality"asregulationstandardand"Darwinoptimality"asempiricalstandard,combiningregulationstandardwithpracticestandard,realisticstandardofvaluejudgmentwithultimatestandard,andfairnesswithefficiency.Thispaperprovidestheoreticalreferenceandanoperationplatformforapplicationandimplementationdifferentialchargesandthecontainmentofcorruptionincollegeenrollment.

  • 标签: 高等教育 微分电荷 双轨迹电荷系统 最优性
  • 简介:ThispaperstartswiththediscussionoftheprincipleofReduced-Rank(RR)Space-TimeAdaptiveProcessing(STAP).Itisfollowedbyadedicationoftheupperboundperformanceofalleigen-basedRRmethodsprovidedbyCrossSpectralMethod(CSM)undertheconditionofagivenprocessorrankandanidenticalsecondarysamplesize.AperformancecomparisonbetweentwoRRSTAPprocessorswithprefixedstructureandCSMisperformedbythemeansofsimulations.Itisshownthattheperformanceoftimepre-filteringfollowedbyjointlylocalizedSTAPstructure(i.e.3DT-SAP)isveryclosetotheupperboundandtherebyitisaneffectiveRRapproach.

  • 标签: Airborne phased array RADAR REDUCED-RANK STAP
  • 简介:联合同轴的共鸣器的现象的模式的研究与理论被进行了。通过建立没有来源的传播线方程,有一个弄皱的内部售票员的同轴的共鸣器的边界条件被分析。最后,计算为Karlsruhe工学院(工具包)的共鸣器在大量折皱参数被执行相关同轴的振动陀螺仪。

  • 标签: 同轴谐振器 模式耦合 波纹参数 传输线方程 耦合现象 边界条件
  • 简介:Greysequencegenerationcandrawoutanddevelopimpliedrulesoftheoriginaldata.Differentkindsofgenerationmethodsweresummarizedandclassifiedintotwotypes:partialgenerationandwholegeneration.Theaveragegenerationandstepwiseratiogenerationisdisussed,thepreferencegenerationisregardasaspecialcaseofproportionaldivisionbasedonanalysisgeometrictheory,proposeanideaofusingconcaveandconvexstatusofdiscretedatatodeterminethegenerationcoefficient.Basedonthestepwiseandsmoothratiogeneration,atendencyaveragegenerationisproposedandhaveacomparisonusingthedataprovidedinpaperslistedinthereferences.Thecomparisonprovesthatthenewgenerationisbetterthantheothertwogenerationsanderrorsareobviouslyreduced.

  • 标签: 灰色系统 数据序列 平均产生 原始数据
  • 简介:Anin-depthexplorationhasbeenmadeoftelecommunicationtariffanditsdecisionsupportsystem.Itisthefirstattempttoconductsuchastudybytheintegrateduseofeconometrics,systememulationandsystemdynamics.Apractically-demandedcostmodelofthetelecommunicationtariffdecisionisproposed.Thesystemhasbeenverifiedwithrealdata.

  • 标签: 电信 关税 计量经济学 系统仿真 系统动力学
  • 简介:ThemathematicalmodelofspaceborneSARsystemsanditscomputersimulationsaredescribed.Resultsofcomputersimulationsaboutrangemigration,rangemigrationcorrection,azimuthweightingandsignalgeneration/processingaregiven.ThissoftwarecanbeusedtosimulatethedynamicprocessesinspaceborneSARsystems,todevelopnewsignalprocessingtechniquesandtoevaluatetheperformanceofthedesignedsystem.

  • 标签: SPACEBORNE SAR system SIMULATION DIGITAL SIGNAL
  • 简介:Thewavelettransformhasremarkableadvantagesandwideapplicationsindenoisingbecauseofitscharacteristicofgoodtime-frequency.Basedontheanalysisoftraditionalwaveletdenoisingmethods,whicharebasedonFouriertransform,animprovedmethodisproposed.ItovercomestheshortcomingsofthetraditionalFourierdenoisingmethod.Inthispaper,thedenoisingproceduresareintroducedrespectivelybasedonthewavelettransformandthemethodofconnectingthewaveletthresholdwiththewaveletbasisisadopted.ThroughMatlabsimulationandconcretedata,itarrivesattheconclusionthatthemethodofsignaldenoisingbasedonthewavelettransformisobviouslymoreeffectiveandbetterthanthetraditionalmethodbasedonFouriertransform.

  • 标签:
  • 简介:Anovelellipsoidalhelicalantennaisproposedandstudiedinthisletter.Asaspecialin-stance,thehemisphericalhelicalantennasareanalyzedfirstly,whichindicatesthatthecharacteristicsofatwo-armunitarebetterthanthatofasingle-armunit.Basedonthis,theellipsoidalhelicalantenna,formedbychangingtheaxialdirection’sdimensionofthetwo-armhemisphericalhelicalantenna,isanalyzedbythemomentmethodwithcurvedbasicandtestingfunction.TheeffectstoVSWR(VoltageStandingWaveRatio),gain,polarizationandpatternsbytheaxialdirection’sdimensionsareinves-tigated.Thestudyresultsprovidedependablegisttothechoiceofantennaformataccordingtothepracticalrequirements.

  • 标签: 半球型螺旋天线 椭圆体螺旋天线 辐射类型 力矩法 分析方法
  • 简介:Whenthereturnscomefromtwoormoreunresolvedtargets(thesignalsarenotresolvedinthefrequencyortimedomains)inamonopulseradarsystem,thedirection-of-arrival(DOA)estimateindicatedbythemonopulseratioisnotthetrueinformationofthetrackedtarget.Thenthetrackingsystemsisinfluenced.Anapproachhasbeenproposedtodetectwhetherthereturnscomefromasingletargetortwounresolvedtargets.Theaboveapproachisextendedfromtwotothreeunresolvedtargets.Thesimulationindicatesthatthedetectionprobabilityunderthethreeunresolvedtargetsisnotsuretoexceedthedetectionprobabilityunderthetwounresolvedtargets.

  • 标签: DOA 单脉冲雷达 检测概率 时域
  • 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

  • 标签: 电信 关税 价格 法规 成本
  • 简介:ZnTe/ZnTe∶Culayerisusedasacomplexbackcontact.TheparametersofCdTesolarcellswithandwithoutthecomplexbackcontactsarecompared.Theeffectsofun-dopedlayerthickness,dopedconcentrationandpost-depositionannealingtemperatureofthecomplexlayeronsolarcellsperformanceareinvestigated.TheresultsshowthatZnTe/ZnTe∶CulayercanimprovebackcontactsandlargelyincreasetheconversionefficiencyofCdTesolarcells.Un-dopedlayerandpost-depositionannealingofhightemperaturecanincreaseopenvoltage.Usingthecomplexbackcontact,asmallCdTecellwithfillfactorof73.14%andconversionefficiencyof12.93%isobtained.

  • 标签: 太阳能电池 碲化镉 CDTE 转换效率 复杂静合接点
  • 简介:ThelowresistancePTCceramicthermistormaterialwithexcellenteleectricalpropertiesaresuccessfullyfabricatedbyrawmaterialsatindustrialrangemadeinourcountryonthestudyofitscompositionexpressionandfabricationprocessbyusingtheadditionofNb,La,Y,Ta,microstructureregulatorBNandASTLphase.Thecompositionanditsfabricationmethodarestudied.TherelationofelectricalpropertiesofthePTCceramicmaterialtoitscompositionexpressionanditsrelatedelectricalpropertiesarediscussed.

  • 标签: 半导体陶瓷 低电阻 PTC 正温度系数 热敏电阻
  • 简介:Differenceexpansion(DE)isoneofthefamousschemesinthefieldofreversibledatahiding.Withthehighefficiencyandsimplicity,DEalsohasreceivedmoreattentionovertheyears.DEhasagoodinformationcapacity,butduetoitsmajorlocationmap,thepurepayloadisratherlow.Thereforemanyscholarsdidrelevantimprovementswhichletnpixelsasaunitinsteadoftheoriginaltwopixelsasaunitandcanadaptivelyadjustthenumberofembeddingsecretinformationaccordingtothesmoothnessdegreeoftheblock,whichachievestheresultofimprovingtheinformationpayloadortheimagequality.Inthispaper,thestudyofDE-basedreversibledatahidingschemesiscomprehensivelydiscussed.TheperformanceofDEbasedschemesisevaluatedandcomparedintermsofembeddingcapacityandstego-imagequality.

  • 标签: 嵌入 差分 信息隐藏 图像质量 有效载荷 信息能力
  • 简介:在这份报纸,photonic水晶温度传感器的一个模型基于在直photonic水晶波导的水晶microcavity被建议。在在不同温度下面的传感器中的光的传播特征被使用有限差别的时间域(FDTD)模仿方法。热扩大和硅的热眼的效果被考虑。结果证明microcavity的反响的波长作为升起的温度线性地增加。与温度一起的波长移动是6.6下午/愠敲猠畴楤吗??

  • 标签: 水晶温度传感器 光子晶体波导 时域有限差分 谐振波长 FDTD 光传感器
  • 简介:Inthispaper,anewpseudocolormethodtodisplaysoundholospectrogramisproposedandstudied.Onthepictureofsuchafour-dimensionalspectrogram,thehorizontalaxisreferstotime,theverticalaxistofrequency,thecolortophase,andthebrightnesstomagnitude.Anexampleofdisplayisgivenbyemployingtherealizedsystem.

  • 标签: SOUND SPECTRUM Holospectrogram Pseudocolor ENCODING DISPLAY
  • 简介:Fromaneconomicangle,thispaperanalyzesanddemonstratestheirrationalityofthecurrentInternetsettlementofInterconnection;thenpointsoutthattheheavychargesforInternetinterconnectionfromdevelopingcountriestothedevelopedcountrycanbethoughtofasoneofthemainandkeyreasonsthatrestrictthebalanceddevelopmentoftheInternetintheworld,whichcausestheintensificationof'digitaldivide',widensthegapbetweenpoorandrichcountriesandfurtheraggravatesthedisequilibriumoftheglobaleconomicdevelopment;andthustheconclusionisreached:thepublicpolicyselectionshouldbemadebythewholeinternationalsocietyjointlyforpayingcloseattentionandregulatingsettlementsystemsofInternetinterconnectiontodwindle'digitaldivide'throughouttheworld.

  • 标签: 因特网 国际结算 数字分割 网络互联 经济全球化
  • 简介:Amethod,whichcanpredictthevalencebandoffsetsatstrainedlayerheterojunctionsunderdifferentstrainsituationsonlybycalculatingbandstructuresanddeformationparametersofthebulkmaterials,issuggested.Theapplicabilityofthismethodisverifiedbycalculationofthevalencebandoffsetsatstrainedlayerheterojuntions,suchasInP/InAs,InP/GaP,GaAs/InAs,GaP/GaAsandAlAs/InAswithvariousstrainconditions.

  • 标签: 应变 异质结 价电子带偏移 平均带能法 畸变位