学科分类
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5 个结果
  • 简介:Underforcedventilation,thedustdiffusionofundergroundpowerhouseconstructionisinvestigatedusinga3DhighReynoldsnumberk-εmodel.Theinterfacialmomentumtransfersandthewallroughnessinthewallfunctionareconsidered.VentilationinthethirdlayerofundergroundpowerhouseofXiangjiabahydropowerstationisusedasacase.Thegeometricstructurehasadecisiveeffectontheairflowdistribution.Itisconcludedthatthedustconcentrationdecreasesgraduallywiththeincreaseoftheventilationtime.However,iso-concentrationcurveshavethesametendencyafter1800s.Thedustconcentrationmeetstheventilationanddust-preventionhealthstandardafter2300s.ThepredictionbythepresentmodelisconfirmedbytheexperimentalmeasurementbyNakayama.

  • 标签: 地下厂房 粉尘扩散 第三层 扩散模拟 施工 强制通风
  • 简介:Basedonexperimentalresults,thispaperpresentsthatunderspecificvibrationalandsolidifyingconditions,thereareseveralperiodiclayersappearinginthecrystallizationofA1-3%Mgalloy.Themechanismoftheformationofperiodiclayerisdiscussed.Furthermore,theuseofthelayerstoidentifythesolid-liquidinterfaceandtheeffectofsuchlayersonmechanicalpropertiesofalloyhavebeenstudied.

  • 标签: VIBRATION SOLIDIFICATION CRYSTAL growth CRYSTAL structure
  • 简介:Temporalmodedirectnumericalsimulationwasdonefortheprocessoflaminar-turbulenttransitioninanincompressibleboundarylayeronaflatplate.Theanalysisoftheresultsshowedthatduringthebreakdownprocessoflaminar-turbulenttransition,themodificationofthemeanflowprofilebythedisturbancesledtoaremarkablechangeinitsstabilitycharacteristics,manifestedinthesignificantenlargementofthelinearunstablezoneandthemaximumamplificationrate,andledtothatmanymoredisturbanceswereexcitedandenhancedrapidly,correspondinglytheturbulentenergyalsoincreasedrapidly,andthemeanflowprofilesevolvedswiftlyfromlaminartoturbulent.Itwasalsofoundthatiftheobliquewavesintheinitialdisturbancesdidnotformsymmetricalpairs,thesubsequentspan-wisemeanvelocitieswould,ingeneral,benonzeroduetononlinearinteraction,whichwouldhaveagreateffectonthestabilitycharacteristicsandalsoimpliedthattheturbulenceobtainedbydirectnumericalsimulationmightnotbefullyarandomprocess.

  • 标签: 平板 不可压缩边界层 层流 湍流 转捩 崩溃机理
  • 简介:这份报纸基于双层结构建议一条紧缩的极化微条天线。整个天线的带宽被分别地扩展顶和底部层拓宽。在天线结构和尺寸的调整的设计以后,建议天线能两个都在2.33GHz2.97GHz完成左边、右边的圆形的极化。测量结果显示有效带宽是在S乐队的640MHz,相对带宽能与S11完成24%不到15dB。

  • 标签: 天线设计 微带天线 圆极化 S-波段 结构紧凑 频带宽度
  • 简介:基于自动电压,控制(AVC)和电池精力存储控制的改进自动电压协作控制策略(AVCCS)(BESC)被建议让光电的连接格子的系统(PVGS)减轻环境骚乱引起的电压变化。当小环境骚乱发生时,仅仅AVC被使用,当BESC与当大骚乱发生时,制止电压变化的AVC被合并时。决定电压变化的允许的振幅的一个可调节的参数被介绍认识到上述切换的进程。一个基准低电压分发系统包括PVGS被使用商业软件建立挖沉默。模拟结果证明在AVCCS下面的电压满足IEEE标准1547,并且安装电池电容是也减少了。同时,电池服务生活被在控制过程避免经常的控告/解除扩大。

  • 标签: 协调控制策略 自动电压控制 低压配电系统 光伏并网 电压波动 IEEE标准