简介：电视上看到一则某种牌子的电器之广告,内中有audio和video两个字,借贵刊一角谈一谈。不用说,这两个字都是和电器有关的。audio与“音”有关系,video则和“影”有关。audio是指由声音、机械、或电力所造成的频率(audiofrs-quency),具有这种频率的声波每秒钟振动十五至二万次,也就是所谓低周波,是人类所能听得见的。在电器制品中,andio特指电唱机、收音机或电视机的发音部分,平常人们所说的音响设备就叫audioequipment。因此,audio现用来泛指一般与音响有关的东西。

简介：南非对于我来说是一个陌生的地方，来自南非的音箱品牌Vividaudio对于关注音响的朋友同样是许多的神秘感。奇特的箱体设计，独特的喇叭技术和音色等等，都令我等好声之人向往。时逢Vividaudio两位掌门人到访其中国代理香港别超音响公司，我在代理的安排下，

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简介：Onthehypothesisthattheturbulentflowispracticallynotaffectedincharacterbypulsationoftheflow,theformulaforsoundpressurelevelofpulsedjetnoiseisobtainedin90°directionand1meterawayfromthenozzle.Thesteadyjetnoiseis,then,aspecialcasewhenthepulsatingfrequencyiszero.Theresultsagreewellwithexperiments.

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简介：Tomakeaudiowatermarkingaccomplishbothcopyrightprotectionandcontentauthenticationwithlocalization,anovelmultipurposeaudiowatermarkingschemeisproposedinthispaper.Thezero-watermarkingideaisintroducedintothedesignofrobustwatermarkingalgorithmtoensurethetransparencyandtoavoidtheinterferencebetweentherobustwatermarkandthesemi-fragilewatermark.ThepropertyofnaturalaudiothattheVQindicesofDWT-DCTcoefficientsamongneighboringframestendtobeverysimilarisutilizedtoextractessentialfeaturefromthehostaudio,whichisthenusedforwatermarkex-traction.And,thechaoticmappingbasedsemi-fragilewatermarkisembeddedinthedetailwaveletcoefficientsbasedontheinstantaneousmixingmodeloftheindependentcomponentanalysis(ICA)system.Boththerobustandsemi-fragilewatermarkscanbeextractedblindlyandthesemi-fragilewatermarkingalgorithmcanlocalizethetamperingaccurately.Simulationresultsdemonstratetheeffectivenessofouralgorithmintermsoftransparency,security,robustnessandtamperinglocalizationability.

简介：Numericalinvestigationofatransversesonicjetinjectedintoasupersoniccrossflowwascarriedoutusinglarge-eddysimulationforafree-streamMachnumberM=1.6andaReynoldsnumberRe=1.38×10~5basedonthejetdiameter.Effectsofthejet-to-crossflowmomentumratioonvariousfundamentalmechanismsdictatingtheintricateflowphenomena,includingflowstructures,turbulentcharactersandfrequencybehaviors,havebeenstudied.Thecomplexflowstructuresandtherelevantflowfeaturesaredisc...

简介：Anaudiorecoveringmethodofspread-spectrumhiddeninformationisproposedbasedongeneticalgorithm.Inthismethodtheembeddedsequencelengthisconfirmedfirstly,thenthebestestimatedsequencewiththeconfirmedlengthisgotbygeneticalgorithm,finallytheconfidentialmessagehiddeninstego-audiocanberecovered.Usingthisapproach,thehiddeninformationcanberecoveredwithoutanyinformationfromthetransmitter.ThepresentedmethodhasbeenimplementedonPC,andtheexperimentalresultsshowthattheaveragerecoveringcorrectrateishigherthan90%.

简介：Wereportthefabricationprocessofpiezoelectriccellulosepaperandtheenhancementmethodofitspiezoelectricproperty.Stretchingmethodwithdifferentwet-drawingratioswasintroducedtoincreasethepiezoelectricpropertyofcellulosepaperduringregenerationprocess.ItisobservedthattheYoung’smodulusandthepiezoelectricchargeconstantsareverydependentonthedrawingratioandthedirectionofnanofibrilsofpiezoelectricpaper.Usingtheenhancedpiezoelectricproperty,weprovethattheflexibleregeneratedpiezoelectriccellulosecanbeappliedtothepotentialacousticapplicationssuchasthinpiezoelectricpaperspeaker.

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简介：Inthisarticletheemphasiswasgiventothediscussionoftheeffectsofdiameterratioandswirlingoninstabilitycharacterforthegas/liquidcoaxialjetusedbyLiao,etal.[1].Theresultsindicatethatthefinitediameterratiomarkedlyincreasesthemaximumgrowthrate,themostunstablewavenumber,aswellasthecutoffwavenumber.Itimpliesthatthefinitediameterratiowillleadtotheliquidjetbreakuplengthshorterandtheliquiddropsizesmaller.Theeffectoftheswirlingjetsismuchmorecomplex:fortheaxisymmetricperturbationmode,theswirlingenhancestheflowstability,forhelicalperturbation,thedominantinstabilitymodeoccursatn<0.Anditisfoundthatinlongwaveregionthereexistsanewkindofinstabilitymodesatn=1thatwasnotmentionedinLiaoetal.'sarticle.Forthisnewmode,thereappearsadominatedswirlingratioatwhichtheflowhasthemaximumgrowthrate.

简介：Atypeofportwithamovablecoverisdesignedtoincreaseinitialdilutionandpreventseawaterandsedimentsfromintrudingintooutfallsystems.Horizontalradialjetspro-ducedbythistypeofportinacurrentareinvestigatedexperimentallyandtheoretically.TheanalysisbasedonReynolds’equationsandself-similarityhypothesisshowsthatthemaximumve-locityofradialjetsdecayswithr-1.5.Therelationshipsbetweenthewidth,thickness,averagedi-lutionofasubmergedwastefieldalongflow,andtheparametersoftheport,jetandambientareestablishedquantitativelyandverifiedbyexperiments.Itisdemonstratedthatthedilutionofhorizontalradialjetsismuchhigherthanthatofverticalroundjetsandthesurfaceboilpointoftheformerismuchmoredistantthanthatofthelatter.

简介：Anewroutewasdevelopedforthesynthesisofrenewabledecalinwithcyclopentanonewhichcanbederivedfromlignocellulose.Itwasfoundthat1,2,3,4,5,6,7,8-octahydronaphthalenecouldbeselectivelyproducedbythehydrogenation/dehydration/rearrangementof[1,1-bi(cyclopentylidene)]-2-one(i.e.theselfaldolcondensationproductofcyclopentanone)overadual-bedcatalystsystem.Amongtheinvestigatedcatalysts,theRu/CandAmberlyst-15resinexhibitedthehighestactivitiesforthehydrogenationof[1,1-bi(cyclopentylidene)]-2-oneto[1,1-bi(cyclopentan)]-2-olandthedehydration/rearrangementof[1,1-bi(cyclopentan)]-2-olto1,2,3,4,5,6,7,8-octahydronaphthalene,respectively.UsingRu/CandAmberlyst-15resinasthefirstbedandthesecondbedcatalysts,1,2,3,4,5,6,7,8-octahydronaphthalenewasdirectlyproducedinhighcarbonyield(83.7%)undermildconditions(393K,1MPa).Afterbeinghydrogenated,the1,2,3,4,5,6,7,8-octahydronaphthalenewasconvertedtodecalinwhichcanbeusedasadditivetoimprovethethermalstabilityandvolumetricheatvalueofjetfuel.

简介：Thecharacteristicsofalaminarwalljetsubmittedtodifferentconfigurationshavebeenexperimentallyexploredinordertoobtainabetterknowledgeoftransitionmodifications,Infactdifferentparameterscanaccelerateordelaythetransitionusingasmoothorroughsurface,heatedornot,submittedtovibrationsornot.Inthisstudy,significanteffectscanbenoticed.Ithasbeenpossibletomeasurethebeginningofgrowthratesofdisturbanceamplitudeusingawindtunnelandcomparingtheresultswiththelinearstabilitytheory.

简介：Intersil公司日前宣布它已签署了一项收购D2Audio公司的最终协议，后者是一家专门致力于为消费电子、汽车以及专业音频产品等应用领域提供数字音频功率放大器设计的创新领先厂商。至此，Intersil公司成为全球独家拥有智能数字音频功率放大器技术的厂商。

简介：Anew,simpleandefficientfiberaudiotransmissionmethodforthelongdistancesecurecommunicationispresented,whichperformssignalmodulationbythestrain-opticeffectsandsignaldemodulationbytheall-fiberinterferometer.Theinterferometerisatrulypath-matcheddevice,whicheliminatesmuchoftheundesirablenoisebycombiningthereferenceandthesensingarmswithinthesameopticalfiber.Thesinusoidalsignalsadoptedintheexperimentareinafrequencyrangeof300HZ-3400HZandofthemulti-frequency,andthesystemshowsgoodcapabilities,robustsecurityandmaintenanceofaudiointegrity.Thedevicemaybeapplicableinthefieldofpointtopointsecurecommunicationof40kilometerlongtransmissionrange.

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简介：宇瞻科技近期推出一款MP3随身听兼迷你音响产品-AudioStenoAP510。该产品面向讲究时尚品味与高质感的消费族群，采用高阶音效芯片．具有极佳的音效品质。外型采用铝合金材质，是一款集MP3／WMA音乐文件的播放、SD读卡机、USB闪存盘、数字录音机、FM收音机等五大功能干一身，并且操作简易的MP3产品。此外．AP510还具有其独家的音响底座．以及高质感高亮度的OLED屏幕,一颗AA碱性电池供电．可连续播放23小时。