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简介：英国的癌症晚期少年斯蒂芬·萨顿在与时间赛跑，其列出46项遗愿清单中的第一项就是希望为青少年癌症信托基金筹集100万英镑的善款，用以帮助更多的人改善生活。现在他的这个愿望早已实现，善款早已超过300万英镑。为了鼓励斯蒂芬做出的努力，英国首相卡梅伦去医院看望他，并且与他合影留念。

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简介：Thispaperreviewssomeoftheprincipaluses,overalmostsevendecades,ofcorrelations,inbothEulerianandLagrangianframesofreference,ofpropertiesofturbulentflowsatvariablespatiallocationsandvariabletimeinstants.Commonlycalledspace–timecorrelations,theyhavebeenfundamentaltotheoriesandmodelsofturbulenceaswellasfortheanalysesofexperimentalanddirectnumericalsimulationturbulencedata.

简介：Inthisnote,weobtainanasymptoticestimateforthetimederivativeoftheΦ-entropyintermsofthelowerboundoftheBakry–EmeryΓ2curvature.InthecasesofhyperbolicspaceandtheHeisenberggroup(moregenerally,thenilpotentLiegroupofranktwo),weshowthatthetimederivativeoftheΦ-entropyisnon-increasingandconcaveintimet,alsowegetasharpasymptoticboundforthetimederivativeoftheentropyinthesecases.

简介：InthispaperthemethodofcombiningtheBursamodeltointegrateseveralregionaltimeseriestoderiveaunifiedglobaltimeseriesisintroducedindetail.Then,anexampletakenfromCMONOC(CrustalMovementObservationNetworkofChina)isusedtotestifthecombinationmethodisfeasible.Theprecisionoftheintegratedtimeserieswiththecombinationmethodisbelow2mm(North),3mm(East),thatissameastheresultsfromthedirectintegrationofthetimeseriesandtheprecisionofthebaselineisbelow6mm,whichprovesthatthecombinationmethodcanbeusedtointegrateseveralregionaltimeseriestoderiveaunifiedglobaltimeseries.

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简介：Theterahertztime-domainspectroscopy(THz-TDS)systemandtherelatedtechnologyandtheapplicationsinCapitalNormalUniversityarepresented.ThemostoftenusedTHz-TDSsystemasaspectroscopicmeasurementsetupinourlabisintroducedindetail,includingtheTHzradiationsource,theTHzdetectionmethodanditsmeasurement,andthecontrolsystem.THzspectraofvariousmaterialsissummarizedanddiscussed.Thesematerialsincludebutnotlimitedtotwokindsoftypicalmatter—theillegaldrugsandexplosives.Thebiologicalmacro-molecules,cosmeticsandfinechemicalmaterials,ediblepigmentsandfoodadditives,homocysteicacidandrelatedcompounds,heavyionsinsoil,Chinesemedicines,tobaccoandcrops,oilandchemicalproducts,carbonnanotubes,superconductors,andvarioussemiconductorsandtheirheterojunctions,arepresented.THzemissionsfromtheInAsandInNsemiconductorssurfacearecompared.THzspectralinvestigationofmetallicmeshstructuresissummarized.Finally,anoutlookofTHzspectroscopicapplicationsisgiven.

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简介：Prestackreversetimemigration（RTM）isanaccurateimagingmethodofsubsurfacemedia.TheviscoacousticprestackRTMisofpracticalsignificancebecauseitconsiderstheviscosityofthesubsurfacemedia.OneofthestepsofRTMissolvingthewaveequationandextrapolatingthewavefieldforwardandbackward;therefore,solvingaccuratelyandefficientlythewaveequationaffectstheimagingresultsandtheefficiencyofRTM.Inthisstudy,weusetheoptimaltime-spacedomaindispersionhigh-orderfinite-difference（FD）methodtosolvetheviscoacousticwaveequation.Dispersionanalysisandnumericalsimulationsshowthattheoptimaltime-spacedomainFDmethodismoreaccurateandsuppressesthenumericaldispersion.Weusehybridabsorbingboundaryconditionstohandletheboundaryreflection.Wealsousesource-normalizedcross-correlationimagingconditionsformigrationandapplyLaplacefilteringtoremovethelow-frequencynoise.NumericalmodelingsuggeststhattheviscoacousticwaveequationRTMhashigherimagingresolutionthantheacousticwaveequationRTMwhentheviscosityofthesubsurfaceisconsidered.Inaddition,forthewavefieldextrapolation,weusetheadaptivevariable-lengthFDoperatortocalculatethespatialderivativesandimprovethecomputationalefficiencywithoutcompromisingtheaccuracyofthenumericalsolution.

简介：Theattempttorepresentasignalsimultaneouslyintimeandfrequencydomainsisfullofchallenges.TherecentlyproposedadaptiveFourierdecomposition(AFD)offersapracticalapproachtosolvethisproblem.ThispaperpresentstheprinciplesoftheAFDbasedtime-frequencyanalysisinthreeaspects:instantaneousfrequencyanalysis,frequencyspectrumanalysis,andthespectrogramanalysis.AnexperimentisconductedandcomparedwiththeFouriertransforminconvergencerateandshort-timeFouriertransformintime-frequencydistribution.TheproposedapproachperformsbetterthanboththeFouriertransformandshort-timeFouriertransform.

简介：AkindofarchitectureofTime-to-DigitalConverter(TDC)forUltra-WideBand(UWB)applicationispresented.TheproposedTDCisbasedonpulseshrinking,andimplementedinaFieldProgrammableGateArray(FPGA)device.ThepulseshrinkingisrealizedinaloopcontainingtwoProgrammableDelayLines(PDLs)oratwo-channelPDL.Oneline(channel)delaystherisingedgeandtheotherline(channel)delaysthefallingedgeofacirculatingpulse.DelayresolutionofPDLisconvertedintoadigitaloutputcodeunderknownconditionsofpulsewidth.Thisdelayresolutionmeasurementmechanismisdifferentfromtheconventionaltimeintervalmeasurementmechanismbasedonpulseshrinkingofconversionofunknownpulsewidthintoadigitaloutputcode.Thismechanismautomaticallyavoidstheinfluenceofunwantedpulseshrinkingbyanycircuitelementapartfromthelines.TheachievedrelativeerrorsforfourPDLsarewithin0.80%–1.60%.

简介：Stochasticswitchedepidemicsystemswithadiscreteordistributedtimedelayareconstructedandinvestigated.BytheLyapunovmethodandIt?o’sdifferentialrule,theexistenceanduniquenessofglobalpositivesolutionofeachsystemisproved.Andstabilityconditionsofthedisease-freeequilibriumofthesystemsareobtained.Numericalsimulationsarepresentedtoillustratetheresults.

简介：Itisknownthatthereisalagtimeforsmokeplumeinducedbyfirestransportingfromafireorigintothelocationofinterestunderneathanunconfinedandflatceiling.Thislagbehaviorofsmokeplumealsoexistsforafireunderaslopedceiling,andisfundamentaltoestimatetheactivationtimeofafiredetectororotherfireextinguishingsystem.Thisstudyfocusesonthelagtimeofsmokeplumeunderaslopedceiling.Basedontheweak-plumetheoryatearly-firephaseandpreviousstudiesconcerningthefireplumecharacteristicsunderaslopedceiling,acalculationmethodonlagtimeoffireplumetransportingispresentedintheory.Meanwhile,twodimensionlessequationspredictingthelagtimeoffireplumeforsteadyfireandunsteadyfireareproposedrespectively.Furthermore,thecriticaltimecalculationequationisalsoproposedtodeterminetheapplicabilityofquasi-steadyassumptionforatime-dependentfire.

简介：Inthispaper,aunifiedmodelfortime-dependentMaxwellequationsindispersivemediaisconsidered.Thespace-timeDGmethoddevelopedin[29]isappliedtosolvetheunderlyingproblem.UnconditionalL2-stabilityanderrorestimateoforderOτr+1+hk+1/2areobtainedwhenpolynomialsofdegreeatmostrandkareusedforthetemporaldiscretizationandspatialdiscretizationrespectively.2-Dand3-Dnumericalexamplesaregiventovalidatethetheoreticalresults.Moreover,numericalresultsshowanultra-convergenceoforder2r+1intemporalvariablet.

简介：ToperformthegroundtestofaspaceborneSyntheticApertureRadar(SAR)system,anechosimulatorwiththecharacteristicsofmultimode,multi-assemblage,andrealtimeisproposedinthispaper.Ahardwareplatformofthereal-timeechosimulatorbasedontheVPXbusisdesigned.Withthisplatform,real-timemulti-pointechogenerationandscenariotargetsechogenerationcanbeachievedbythereal-timesignalprocessinginFieldProgrammableGateArray(FPGA),utilizingtheparameterscalculatedbytheindustrycomputers.Furthermore,thisplatformcanoutputdifferentsignalsifitisexpandedtomulti-channels,makingitpossiblefortheassignmentofechogenerationandtestindifferentspaceborneSARmodes.ThetestresultswiththeactualSARsystemshowthatthisplatformcansatisfythesystemrequirementsandisnowusedinpractice.

简介：Inthispaper,theexponentialstabilityanalysisforODEswitchedsystemswithtimedelayisextendedtodistributedparameterswitchedsystems(DPSS)inHilbertspace.Foragivenfamilyofexponentialstablesubsystems,thispaperfocusesonfindingconditionstoguaranteetheoverallDPSS'exponentialstability.Basedonsemigrouptheory,byapplyingpiecewiseLyapunov-Krasovskiifunctionalsmethodincorporatedaveragedwelltimeapproach,sufficientconditionsforexponentialstabilityarederived.Theseconditionsaregivenintheformoflinearoperatorinequalities(LOIs)wherethedecisionvariablesareoperatorsinHilbertspace,andthestabilitypropertiesdependonswitchingrule.Beingappliedtoheatswitchedpropagationequations,theseLOIsarereducedtostandardLinearMatrixInequalities(LMIs).Finally,anumericalexampleisgiventoillustratetheeffectivenessoftheproposedresult.

简介：时间的不平等的一种新类型被讨论，它适用于算法的进程，包含处理联合起来的有限记忆。他们是Leggett-Grag，以及到由Brukner等的修改的一种选择。如果一个人考虑包含有限存储器的系统的量和古典进程的比较(在两个盒子中的一样的能力)，不平等给我们能期望量加速的一条清楚的消息。在古典进程，一个人清楚地总是定义可能的大小的值，或以信息处理语言如果我们有一取决于到达各个的数据的某功能的顺序的计算走在一个算法上，函数总是有清楚地定义的值。在算法的结束以后，在量盒子中，仅仅最后的价值被定义。与Bohrs补充一致，所有中间的价值不能被归功于明确的价值。

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