简介:Adigitalwatermarkingtechniqueisamulti-scientificdisciplinewhichisdevelopedrapidlyinlastseveralyearsfordigitalcontentprotection,suchascopyrightprotection,authenticationprotection,sourcetracing,etc.However,inrealisticscenarios,thedigitalwatermarkingsystemfacessignificantsecureissues,forexample,theattackerswanttoremove,detect,orembedillegalwatermarksignals.Therefore,theaimofthiscontributionistoillustraterecentresultsofrobustandsecurewatermarkingtothesignalprocessingcommunity,andhighlightbothbenefitsandstillopenissues.Specifically,thispaperisintendedtointroducetheconceptofsecureandrobustdigitalwatermarkingsystem,andprovidewithproblemsandtheircountermeasures.Firstofall,theclassicwatermarkmodelandcryptosystemwillbereviewedandthen,theconceptofsecureandrobustdigitalwatermarkingsystemwillbedescribed.Next,thewatermarkattackwillbeclassifiedanddescribed.Finally,somecountermeasuresthatcanhelptoimprovesecureandrobustnessareconsidered.IndexTermsCountermeasures,digitalwatermarkingsystem,robust,security,watermarkattacks.
简介:亚群发现是关于利息的一个性质在不同变量之中发现有趣的协会的一种数据采矿技术。存在亚群发现方法为寻找采用不同策略,修剪并且评价亚群。学习哪个一个亚群发现算法的特征应该为产生优秀亚群被考虑是很关键的。在这方面,很多评论在亚群发现上被进行了。尽管他们在一些流行亚群发现方法上提供宽广概述,他们为亚群评估采用很少数据集和措施。根据存在措施,亚群不能从所有观点被估价。我们的工作由使用大量数据集并且由为亚群评估定义新措施在一些流行亚群发现方法上执行广泛的分析。分析结果将帮助做好理解主要亚群发现方法,揭开为进一步的改进的差距并且为特定的申请领域选择算法的合适的范畴。
简介:Orthogonalfrequencydivisionmultipleaccess(OFDMA)isapopularandwidelyacceptedmultipleaccesstechniquetoprovidehighdatarateservicesinamobileenvironmentintheareaofwirelesscommunications.OFDMAcanprovidebetterflexibilityinallocatingtheradiospectrabyutilizingsubcarrierallocations,scheduling,andenergycontroltoobtainmulti-dimensiondiversitygains.Duetoitsresourceallocationflexibility,OFDMAhasbeenwidelyusedasagreenairinterfacetechnologyfortheemergingbroadbandwirelessaccessnetworks.ThispaperextensivelyaddressestheintegrationofgreenOFDMAtothefutureairinterfacetechnologies,forinstance:two-tiercellular,multiradioaccesstechnologies(RATs),FemtoCell,andrelaynetworks.ThemainfocusofthepaperistoreviewandanalyzethecurrentOFDMAtechniquestoaddressthegreenresourceallocationinmultiuserdiversity,wherethecriticalconstraintsarethecomputationalcomplexity,energyefficiency,andthesub-channelassignment.ThefuturetrendofOFDMAbasednetworkswillaimtomaximizetheenergyefficiencyoftheexclusivechannelassignmentthroughajointsub-channelandpowerallocationtoaccommodatehighdatatrafficnetworksspeciallytherelaybased5Gcellularnetworks.
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简介:AdetailedsurveyofthereefsintheNanshaIslands’seathatareofstrategicimportanceisconducivetotheirfuturedevelopment.Inthisstudy,atotalof50Landsat8operationallandimager(OLI)imageswereusedtoanalyzethegeologicalfeaturesandspectralcharacteristicsoftheNanshareefs.Theexposedislands/sandbanks,reefflatsandsub-tidalreefswereidentifiedwiththenear-infraredband,theredandgreenbands,andtheblueband,respectively.BasedontherelationshipsamongvariouscharacteristicsandbandsillustratedintheOLIimages,themaximumbetween-clustervariancethresholdalgorithm(OTSUmethod)andthemathematicalmorphologywereemployedtoextractcharacteristicparametersofthespatialgeometryofthereefsfromtoptobottom,whichweresubsequentlyoperatedbyaseriesofpost-processingmethodssuchasvectorization,simplificationandtopologicalanalysis.Amongthe132standalonereefsand16atollsthatareidentifiedinthestudy,fourreefshaveyettobenamedintheStandardNamesofVariousIslandsintheSouthChinaSeaandthewebsiteNanshaIslandsOnline(http://www.nansha.org/).Another24onesareexposedtotheatmosphereevenduringhightides.TaipingIslandwithanareaof0.57km~2representsthelargestexposedgeologicalfeature.Thisstudydemonstratedtheapplicabilityofmedium-resolutionsatelliteimagestoderivethecoralreefinformationeffectivelyandthusprovidedinformationfortherelateddepartmentsthatareresponsibletomanagethecoast.Animprovedresolutionofmultispectralbandswiththepanchromaticbandinhigherspatialresolution(15mforOLIimage)isexpectedtoprovideanoptimumsatellitebasedapproachtomapmarinehabitats.
简介:Theimplementationofwirelesstechnologiesbasedonthevehicularadhocsensornetwork(VASNET)mayprovidesupportforthesearchandrescue(SAR)teamtooperateeffectivelyinnaturaldisasterevents,suchaslandslide,earthquake,flooding,andtsunami.TheoperationsofSARteamareverychallenginginsucheventsduetothepossibledamagesoftheexistingtelecommunicationinfrastructures.Theexistingdeploymentofthecellularcommunicationsinfrastructuremaybepartiallyorcompletelydestroyedaftertheoccurrenceofthesenaturaldisasters.Thus,thecurrentVASNETinfrastructuremustbeabletosupporttheinfrastructure-lessnetworkbyintegratingothergreenwirelesstechnologiesthatcanbenefittheSARteam,whichcanindirectlysavemorehumanlivesandreducethenumberofcasualties.Therefore,theintegrationofgreenInternetofthings(IoT)andVASNETisproposedtoformaheterogeneousframeworkfordatadisseminationinSARoperations.Inaddition,thispaperalsodiscussestheexistingIoTframeworkindisasterscenarioswithfutureresearchdirectionforIoTusingonanyaspect,especiallyrelatedtothenaturaldisasterscenarios.