简介:分布式视频编码具有编码简单、高效压缩等特点,近些年国内外设计实现了多种分布式视频编码算法.本文提出一种基于变换域的分布式视频编码仿真测试软件设计方案,以测试QICF、CIF以4:2:0采样的YUV原始视频文件,通过改变量化参数、提取位平面参数改变视频文件传输比特率,以测试该算法在不同比特率下的率失真性能,通过更改量化表和运动预测搜索半径,搜索块大小,以适用不同序列更改设置,达到最佳性能.该方案可以验证分布式视频编码中各个模块的功能,并可以提出相应模块的各种改进算法验证其性能.
简介:Basedontheprincipleofimpedancemismatching,theperformanceofrigidvibrationisolationmassinimpedingvibrationwavepropagationwasdiscussedfromtheperspectiveofwaveapproach.BasedonFEM,theinfluenceofitsweightaswellasthecross-sectionshapeparametersontheisolationperformanceofrigidvibrationisolationmasswasstudiedthroughnumericalsimulation.Theresultsshowthatrigidvibrationisolationmasscaneffectivelyimpedethepropagationofthemediumandhighfrequencyvibrationwaves,andtheheavierthevibrationisolationmass,thebettertheisolationperformance.Forlowfrequencywaves,thevibrationisolationeffectisnotsoobvious;forarectangularvibrationisolationmass,theisolationperformancecouldbeeffectivelyimprovedbyincreasingthecross-sectionheightandreducingthecross-sectionwidth.Ausefulreferencewasprovidedfortheapplicationofrigidvibrationisolationmassestothevibrationisolationandnoisereductionofshipstructure.
简介:Inconsideringthetheoryofstructuraldynamicoptimizationdesign,adesignmethodofthestructuralstyleofshipcompositebracewithrigidvibrationisolationmasswasstudied.Twokindsofstructuraldynamicoptimizationformulationsminimizingthevibrationaccelerationofthenon-pressurehullontherestrainingconditionofthegrossweightoftheshipcabinwereestablished:1)dynamicoptimizationofthesectionaldimensionsoftherigidvibrationisolationmassinthecompositebrace;2)dynamicoptimizationofthearrangingpositionoftherigidvibrationisolationmass.Throughtheoptimizationresults,sectionaldimensionsandthearrangingpositionoftherigidvibrationisolationmasswithbetterperformanceinreducingvibrationweregained,andsomereferencewasprovidedforpracticalengineeringdesignsaswellasenrichmentofthedesignmethodofanovelshipvibration-isolationbrace.
简介:Severalindustrialapplicationssuchaselectronicdevices,heatexchangers,gasturbineblades,etc.needcoolingprocesses.Theinternalcoolingtechniqueisproperforsomeapplications.Inthepresentwork,computationalsimulationsweremadeusingANSYSCFXtopredicttheimprovementsofinternalheattransferintherectangularribbedchannelusingdifferentcoolants.Severalcoolantssuchasair,steam,air/mistandsteam/mistwereinvestigated.Theshearstresstransportmodel(SST)isselectedbycomparingthestandardk-ωandOmegaReynoldsStress(ωRS)turbulencemodelswithexperimentalresults.Theresultsindicatethattheheattransfercoefficientsareenhancedintheribbedchannelwhileinjectingsmallamountsofmist.Theheattransfercoefficientsofair/mist,steamandsteam/mistincreaseby12.5%,49.5%and107%overthatofair,respectively.Furthermore,incomparisontoair,theair/mistheattransfercoefficientenhancesbyabout1.05to1.14timeswhenthemistmassfractionincreasesfrom2%to8%,respectively.Thesteam/mistheattransfercoefficientincreasesbyabout1.12to1.27timeshigherthanthatofsteamovertheconsideredrangeofmistmassfraction.
简介:应用密度泛函理论中的ω-B97XD/6-311+G(d,p)方法,对甲湛分子团簇[CH2O]n(n=1~4)的空间结构进行了优化,得到了这些团簇的基态结构,并对其红外光谱,核磁共振谱的性质进行了研究.结果表明,当甲醛分子构成稳定的多分子团簇时,团簇中的每个分子仍然为平面结构,分子间将形成氢键,并且团簇中的各个分子共面.与单分子甲醛相比,多分子团簇的红外光谱,会出现许多与分子间氢键振动有关的新的吸收峰.当甲醛分子形成团簇时,13C核和17O核的核磁共振谱线会发生劈裂现象,这与电荷分布的对称性的破缺有关;而1H的核磁共振谱中将会出现新的条纹,这是由分子间的氢键的形成引起的.本文的研究可为甲醛团簇的识别、检测及性质研究提供理论依据.
简介:Smoothedparticlehydrodynamics(SPH)isaLagrangianmeshlessparticlemethod.Itisoneofthebestmethodforsimulatingviolentfreesurfaceflowsinfluidsandsolvinglargefluiddeformations.Dambreakingisatypicalexampleoftheseproblems.ThebasisofSPHwasreviewed,includingsometechniquesforgoverningequationresolution,suchasthesteppingmethodandtheboundaryhandlingmethod.Thennumericalresultsofadambreakingsimulationwerediscussed,andthebenefitsofconceptslikeartificialviscosityandpositioncorrectionwereanalyzedindetail.Whencomparedwithdambreakingsimulatedbythevolumeoffluid(VOF)method,thewaveprofilegeneratedbySPHhadgoodagreement,butthepressurehadonlyreasonableagreement.Improvingpressureresultsisclearlyanimportantnextstepforresearch.
简介:以集装箱班轮航线为基础,构建以港口为节点、港口间的运力为边权重的有向加权海运网络,并从中抽取出与广州港、深圳港以及香港港有联系的港口节点和边.在此基础上,分别从出口货流和进口货流两个角度对广州港、深圳港以及香港港的集装箱货流在全球17个海运区域的空间分布情况进行对比,并就出口货流和进口货流在上述三个港口之间的集聚程度进行了分析.结果表明:(1)无论是在进口货流还是出口货流方面,与香港港建立联系的海运区域数量都是最多的,香港港的港口通达性最好;(2)深圳港的货流总量高于香港港和广州港;(3)进口货流主要集中在香港港,出口货流主要集中在深圳港;(4)东非、南部非洲、南美东岸和西非区域的进口货流呈现高度集聚分布的特点.
简介:利用FLUENT软件数值计算了二维柔性鳍作升沉纵摇运动时的推力系数及推进效率,探讨了修正Bose变形方程、均匀载荷和非均匀载荷悬臂梁变形方程等三种柔性模式下纵摇轴位置对摆动鳍推进性能的影响,其中纵摇轴在尾缘处能够获得更大的推力,而最高的推进效率分别对应修正Bose模式下纵摇轴距首缘1/3弦长处和悬臂梁柔性变形模型下纵摇轴距首缘2/3弦长处.同时计算分析了斯特劳哈尔数、最大攻角等参数对柔性鳍水动力性能的影响,建立了最大推力系数和最高推进效率所对应的参数区间,其中低St数的最高推进效率发生在低αmax,高St数的最高推进效率发生在高αmax.