简介：Anewhigh-ordermulti-jointfiniteelementforthin-walledbarwasderivedfromtheHermiteinterpolationpolynomialandminimumpotentialenergyprinciple.Thiselement'scharacteristicsarethatitisofhighaccuracyandcanbeusedinfinitemethodanalysisofbridge,tallmega-structurebuilding.

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简介：Thesubsystemsynthesismethodhasbeendevelopedinordertoimprovecomputationalefficiencyforamultibodyvehicledynamicsmodel.Usingthesubsystemsynthesismethod,equationsofmotionofthebasebodyandeachsubsystemcanbesolvedseparately.Inthesubsystemsynthesismethod,variouscoordinatesystemscanbeusedandvariousintegrationmethodscanbeappliedineachsubsystem,aslongastheeffectivemassmatrixandtheeffectiveforcevectorareproperlyproduced.Inthispaper,comparativestudyhasbeencarriedoutforthesubsystemsynthesismethodwithCartesiancoordinatesandwithjointrelativecoordinates.Twodifferentintegrationmethodssuchasanexplicitintegratorandanexplicitimplicitintegratorareemployed.Inordertoseetheaccuracyandcomputationalefficiencyfromthedifferentmodelsbasedonthedifferentcoordinatesystemsanddifferentintegrationmethods,aroughterrainrunsimulationshasbeencarriedoutwitha6×6off-roadmultibodyvehiclemodel.

简介：ThispaperproposesanadaptivejointsourceandchannelcodingschemeforH.264videomulticastoverwirelessLANwhichtakesintoaccounttheusertopologychangesandvaryingchannelconditionsofmultipleusers,anddynamicallyallocatesavailablebandwidthbetweensourcecodingandchannelcoding,withthegoaltooptimizetheoverallsystemperformance.Inparticular,sourceresilienceanderrorcorrectionareconsideredjointlyintheschemetoachievetheoptimalperformance.Andachannelestimationalgorithmbasedontheaveragepacketlossrateandthevarianceofpacketlossrateisproposedalso.Twooverallperformancecriteriaforvideomulticastareinvestigatedandexperimentalresultsarepresentedtoshowtheimprovementobtainedbythescheme.

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简介：由静态的张力的力量和关节的失败机制上的合成大头针(Z大头针)的通过厚度加强的效果用陶器的矩阵做了合成(CMC)被调查。单个臀部关节的重叠长度分别地是15公里，20公里，23公里，37公里，和60公里。试验性的结果显示关节的最后的失败模式能被划分成二个组，(a)契约线站debonding直到快克遇到Z大头针；然后在Z大头针的地点的adherends裂缝，当重叠长度是超过20公里时；(b)契约线完全分开并且Z大头针从adherends被拉，当重叠长度等于15公里时。一条简单有效计算途径为为在单个臀部关节限制失败分析通过厚度大头针的利益被介绍。这里，力学问题被由对击碎的契约线的破裂表面起作用的拖拉代表大头针的效果简化。拖拉作为裂缝排水量的功能被规定，它在总结复杂变丑到合理精确性的简单形式是可得到的。产生模型能被用来例如，追踪完全的失败机制的进化起始的分层和最终的失败与Z大头针撤退联系了的契约线，adherends的最终的失败。纸与不同Z-pins'直径，间距和重叠长度模仿单个臀部关节的连接性能；数字结果同意试验性的结果；数字结果显示扩大直径和Z大头针的减少的间距赞成改进关节的连接表演。由数字分析方法，当Z-pins'直径和间距是0.4公里时，躺在二个最后的失败模式之间的批评重叠长度在18公里和19公里之间，5公里分别地。

简介：Inthisinvestigation,amodelingprocedureofatelescopicboomofcranesisdevelopedusingtheabsolutenodalcoordinateformulationtogetherwiththeslidingjointconstraints.Sincetelescopicboomsareextractedandretractedundervariousoperatingconditions,theoveralllengthoftheboomchangesdynamically,leadingtothetime-variantvibrationcharacteristics.Formodelingthetelescopicstructureofbooms,aspecialcareneedstobeexercisedsincethelocationoftheslidingcontactpointmovesalongthedeformableaxisoftheflexibleboomandthesolutiontoamovingboundaryproblemisrequired.Thisissueindeedmakesthemodelingofthetelescopicboomdifficult,despitethesignificantneedsfortheanalysis.Itis,therefore,theobjectiveofthisinvestigationtodevelopamodelingprocedurefortheflexibletelescopicboombyconsideringtheslidingcontactconditionwiththedynamicfrictionaleffect.Tothisend,theslidingjointconstraintdevelopedfortheabsolutenodalcoordinateformulationisemployedfordescribingrelativeslidingmotionbetweenflexiblebooms,whileflexibleboomsaremodeledusingthebeamelementoftheabsolutenodalcoordinateformulation,whichallowsformodelingthelargerotationanddeformationofthestructure.

简介：Thispaperintroducesajointnonlinearityandchromaticdispersionpre-compensationmethodforcoherentopticalorthogonalfrequency-divisionmultiplexingsystems.Theresearchresultsshowthatthismethodcanreducethewalk-offeffectandcanthereforeequalizethenonlinearimpairmentseffectively.Comparedwiththeonlyotherexistingnonlinearitypre-compensationmethod,thejointnonlinearityandchromaticdispersionpre-compensationmethodisnotonlysuitableforlow-dispersionopticalorthogonalfrequency-divisionmultiplexingsystem,butalsoeffectiveforhigh-dispersionopticalorthogonalfrequency-divisionmultiplexingtransmissionsystemwithhigherinputpowerbutwithoutopticaldispersioncompensation.Thesuggestedsolutiondoesnotincreasecomputationcomplexitycomparedwithonlynonlinearitypre-compensationmethod.For40Gbit/scoherentopticalorthogonalfrequency-divisionmultiplexing20×80kmstandardsingle-modefibresystem,thesuggestedmethodcanimprovethenonlinearthreshold(forQ>10dB)about2.7,1.2and1.0dB,andthemaximumQfactorabout1.2,0.4and0.3dB,for2,8and16ps/(nm·km)dispersioncoefficients.

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简介：TheHongKongObservatory(HKO)provideslow-levelturbulencealertingservicefortheHongKongInternationalAirport(HKIA)throughthewindshearandturbulencewarningsystem(WTWS).IntheWTWS,turbulenceintensitiesalongtheflightpathsoftheairportareestimatedbaseduponcorrelationequationsestablishedbetweenthesurfaceanemometerdataandtheturbulencedatafromresearchaircraftbeforetheopeningoftheairport.Theresearchaircraftdataarenotavailableonday-to-daybasis.Theremotesensingmeteorologicalinstruments,suchastheDopplerlightdetectionandranging(LIDAR)andradar,maybeusedtoprovidedirectmeasurementsofturbulenceintensitiesovertherunwaycorridors.TheperformancesofLIDAR-andradar-basedturbulenceintensitydataarestudiedinthispaperbasedonactualturbulenceintensitymeasurementsmadeon423commercialjetsforatypicalcaseofterrain-inducedturbulenceinassociationwithatyphoon.Itturnsoutthat,withthetuningoftherelativeoperatingcharacteristic(ROC)curvebetweenhitrateandfalsealarmrate,theLIDAR-basedturbulenceintensitymeasurementperformsbetterthantheanemometer-basedestimationofWTWSforturbulenceintensityatmoderatelevelorabove.Ontheotherhand,theradar-basedmeasurementdoesnotperformaswellwhencomparedwithWTWS.BycombiningLIDAR-andradar-basedmeasurements,theperformanceisslightlybetterthanWTWS,mainlyasaresultofcontributionfromLIDAR-basedmeasurement.Asaresult,theLIDAR-basedturbulenceintensitymeasurementcouldbeusedtoreplaceanemometer-basedestimatefornon-rainyweatherconditions.Furtherenhancementsofradar-basedturbulenceintensitymeasurementinrainwouldbenecessary.

简介：ZnOfilmscontainingErandGenanocrystals（nc-Ge）weresynthesizedandtheirphotoluminescence（PL）propertieswerestudied.Visibleandnear-infraredPLintensitiesarefoundtobegreatlyincreasedinnc-Ge-containingfilm.Er-related1.54μmemissionhasbeeninvestigatedunderseveralexcitationconditionsupondifferentkindsofGe,ErcodopedZnOthinfilms.1.54μmPLenhancementaccompaniedbytheappearanceofnc-Geimpliesasignificantcorrelationbetweennc-GeandPLemissionofEr3+.Theincreasedintensityof1.54μminGe:Er:ZnOfilmisconsideredtocomefromthejointeffectofthelocalpotentialdistortionaroundEr3+andthepossibleenergytransferfromnc-GetoEr3+.