简介:在极的同温层的云(PSC)的液体和稳固的粒子被知道了在迟了的冬季和早春在南极和北极区域上在同温层的臭氧的化学损失起一个关键作用。同温层的喷雾器和云粒子提供快异构的化学反应把不活跃的卤素水库种类变换成消灭激进分子的潜在的臭氧的地点。氮的酸包含的PSCparticles的沉积不可逆转地把HNO_3气体(denitrification)从更低的平流层移开,它减缓氯的回来到它的不活跃的形式,导致更多的严重同温层的臭氧破坏。尽管这些云在在situ领域观察,实验室实验和当模特儿的研究使用的过去的十年期间广泛地被调查了,在冷同温层的条件下面的详细微视物理学过程仍然是不明确的。这篇论文在我们PSC的理解考察最近的进展。
简介:TheaimofthisstudyistoinvestigateexperimentallytheeffectofsurfaceroughnessoncloudcavitationaroundClark-Yhydrofoils.High-speedvideoandparticleimagevelocimetry(PIV)wereusedtoobtaincavitationpatternsimages(Prog.Aerosp.Sci.37:551–581,2001),aswellasvelocityandvorticityfields.ResultsarepresentedforcloudcavitatingconditionsaroundaClark-Yhydrofoilfixedatangleofattackofα=8?formoderateReynoldsnumberofRe=5.6×105.Theresultsshowthatroughnesshadagreatinfluenceonthepattern,velocityandvorticitydistributionofcloudcavitation.Forcavitatingflowaroundasmoothhydrofoil(A)andaroughhydrofoil(B),cloudcavitationoccurredintheformoffinger-likecavitiesandattachedsubulatecavities,respectively.TheperiodofcloudcavitationaroundhydrofoilAwasshorterthanforhydrofoilB.Surfaceroughnesshadagreatinfluenceontheprocessofcloudcavitation.ThedevelopmentofcloudcavitationaroundhydrofoilAconsistedoftwostages:(1)Attachedcavitiesdevelopedalongthesurfacetothetrailingedge;(2)Areentrantjetdeveloped,resultinginsheddingandcollapseofclusterbubblesorvortexstructure.Meanwhile,itsdevelopmentforhydrofoilBincludedthreestages:(1)Attachedcavitiesdevelopedalongthesurfacetothetrailingedge,withaccumulationandrotationofbubblesatthetrailingedgeofthehydrofoilaffectingtheflowfield;(2)Developmentofareentrantjetresultedinthefirstsheddingofcavities.Interactionandmovementofflowsfromthepressuresideandsuctionsidebroughtliquidwaterfromthepressuresidetothesuctionsideofthehydrofoil,finallyformingareentrantjet.Thejetkeptmovingalongthesurfacetotheleadingedgeofthehydrofoil,resultinginlarge-scalesheddingofcloudbubbles.Severalvorticesappearedanddissipatedduringtheprocess;(3)Cavitiesgrewandshedagain.
简介:Basedonarelativisticquarkmodelapproach,thetransitionpropertiesofthefirstnucleonresonance△(1232),andthecouplingconstantsgπNN,g△πNareinvestigated.Tvodifferentvaystoremovethecenterofmassmotionareconsidered.Theresultsoftherelativisticapproacheswithandwithoutcenterofmasscorrectionarecomparedwiththoseofnonrelativisticconstituentquarkmodel.Moreover,pionmesoncloudeffectonthesecalculatedobservablesisexplicitlyaddressed.Betterresultsareobtainedbytakingthepionmesoncloudintoaccount.
简介:由与链纠纷的不同的度准备同质的混合样品,我们报导链纠纷的异常贡献分阶段执行分离温度和介绍典型更低的批评答案温度LCST行为的polymethylmethacrylate/polystyrene-co-maleic酐PMMA/SMA混合的率。有更高的链纠纷密度的meltmixedPMMA/SMA混合介绍更低的云点Tc和更短的延期时间,而是更低的阶段分离比答案演员组在给定的温度评价,为聚合物建议那与不同压缩状态相配结构,热力学地,分阶段执行分离的更多的容易降低Tc未必等价于更快的动力学分解率。试验性的结果显示更低的T融化混合样品的c被归功于到更小的集中变化波长m由更高的纠纷度导致了,当在融化混合样品的更高的纠纷度导致限制部分动力学时并且因而,更慢的动力学分解率由macromolecular散开统治了在一可比较熄灭深度。这些结果表明在聚合物混合收拾行李的链能显著地影响液体液体阶段分离行为,它是从小分子的混合物的分解的重要差别。