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硫酸钠水溶液的受激拉曼散射高效频率转换和交叉泵浦研究哎呀，您这问题可真是让我为难啊！不过，既然您那么要求，那我就尽量给您写一篇通俗易懂的文章吧。
话说这个硫酸钠水溶液的受激拉曼散射高效频率转换和交叉泵浦研究，听起来就像是一堆高科技的东西，让人有点儿摸不着头脑。
不过，别着急，我给您慢慢道来。
我们来说说这个硫酸钠水溶液。
这可不是什么普通的水溶液哦，它可是含有硫酸钠的。
硫酸钠？听起来好像是一种化学物质，但是别担心，它其实是一种很常见的盐类物质。
在我们的日常生活中，很多东西都含有这种物质，比如咸菜、豆腐等等。
这个硫酸钠水溶液并不是什么神秘的东西，咱们老百姓也能理解。
我们再来说说受激拉曼散射。
这个名词听起来就很高级，好像是物理学家们才会用的词汇。
其实，受激拉曼散射就是指一种光的传播方式。
当一束光子与某种物质相互作用时，可能会发生受激拉曼散射现象。
这种现象可以帮助我们了解物质的结构和性质。
受激拉曼散射虽然听起来复杂，但实际上是我们日常生活中的一部分。
现在，我们来说说高效频率转换。
这个词组听起来好像是用来形容什么高科技设备的。
实际上，高效频率转换就是指将一种信号转换成另一种信号的过程。
在这个过程中，信号的损失要尽量减少，以保证信息传输的准确性。
这个概念在我们的日常生活中也有很多应用，比如手机信号转换、无线电通信等等。
我们来说说交叉泵浦。
这个词组听起来好像是一个专业术语，但是实际上它也是我们日常生活中的一部分。
交叉泵浦是指两个或多个泵浦同时工作的过程。
在科学研究中，交叉泵浦可以用来提高实验的效率。
而在我们的日常生活中，交叉泵浦的例子也有很多，比如地铁、公交车的运行就是典型的交叉泵浦过程。
这个硫酸钠水溶液的受激拉曼散射高效频率转换和交叉泵浦研究并不是什么高深莫测的东西。
相反，它涉及到了很多我们日常生活中常见的概念和现象。
通过这个研究，科学家们可以更好地了解物质的结构和性质，从而为我们的生活带来更多的便利和创新。
咱们老百姓也可以对这个话题感兴趣，毕竟它关系到我们的日常生活嘛！。
大学物理之超流体与超导电性的关系Superfluidity and superconductivity are two fascinating phenomena in physics that exhibit remarkable properties at extremely low temperatures. Although they seem distinct at first glance, there are interesting parallels and connections between them.Superfluidity, typically observed in liquid helium-4 at temperatures close to absolute zero, refers to a state where the fluid exhibits frictionless flow and quantized vortices. In this state, the atoms move in a highly coordinated manner, giving rise to unique transport properties. Superfluid helium, for instance, can climb the walls of its container and flow without any apparent resistance.On the other hand, superconductivity is a phenomenon observed in certain materials, primarily metals and alloys, at low temperatures. In a superconducting state, the material exhibits zero electrical resistance and the expulsion of magnetic fields, known as the Meissner effect. This allows for the lossless flow of electrical current, a crucial property for applications like superconducting magnets and cables.While the microscopic mechanisms underlying superfluidity and superconductivity differ, both phenomena involve the coherent motion of particles at the quantum level. In superfluid helium, the atoms move in a coordinated manner, while in superconductors, the electrons form Cooper pairs that move collectively without resistance. This collective behavior is a key aspect of both superfluidity and superconductivity.Furthermore, both superfluids and superconductors exhibit critical temperatures below which the respective phenomena occur. Above these temperatures, the systems revert to their normal states, losing their unique properties. This similarity suggests that there may be deeper connections between superfluidity and superconductivity that await further exploration.In summary, superfluidity and superconductivity are remarkable examples of quantum phenomena that exhibit unique properties at low temperatures. While their microscopic origins differ, they share common features such as collective particle motion and critical temperatures. Studying these parallels can provide insights into the fundamental laws of physics and potentially lead to new technological applications.。
海水中的直流水平电偶极子在界面处产生的电磁场
王西乾;韩逍菲;彭怀云;陈宇
【期刊名称】《电波科学学报》
【年(卷),期】2014(29)6
【摘要】舰船底部附近的电化学电流会产生恒定电磁场,研究这种电磁场分布对水下侦测舰船非常重要.文中将该场源理想化为一个直流水平电偶极子,这一直流水平电偶板子是低频电偶极子在频率趋于0时的极限情况.利用贝赛尔函数的性质,将这些积分表达式简化为一系列简单的解析表达式,并在该表达式的基础上进行分析讨论算出电磁场的空间分布.
【总页数】7页(P1030-1035,1056)
【作者】王西乾;韩逍菲;彭怀云;陈宇
【作者单位】中国电波传播研究所,山东青岛266107;中国电波传播研究所,山东青岛266107;西安电子科技大学,陕西西安710071;中国电波传播研究所,山东青岛266107
【正文语种】中文
【中图分类】TN01
【相关文献】
1.分层媒质中极低频水平电偶极子在绝缘介质半空间中产生的电磁场 [J], 陈聪;龚沈光;卢新城;周骏
2.海水中极低频水平电偶极子电磁场的解析解 [J], 卢新城;龚沈光;周骏;孙明
3.水平电偶极子在覆盖有等离子体的良导体上产生的电磁场的研究 [J], 林国华;张业荣
4.用气—水—土3层模型分析海水中水平电偶极子源的电磁场分布 [J], 柳超;梁高权
5.非均匀海水中水平电偶极子在空气中产生的电磁场 [J], 任英达;王宏磊;杨坤德因版权原因，仅展示原文概要，查看原文内容请购买。
半绝缘GaAs光电导开关的延迟偶极畴工作模式(英文)
田立强;施卫
【期刊名称】《半导体学报：英文版》
【年(卷),期】2007(28)6
【摘要】基于转移电子效应提出半绝缘光电导开关延迟偶极畴工作模式,理论分析了强场下开关的周期性减幅振荡.指出开关的周期性减幅振荡是由于外电路的自激
振荡和开关的转移电子振荡共同作用引起的.开关的偏置电场在交流电场的调制下,当畴到达阳极时,开关电场下降到低于耿氏阈值电场ET而高于维持电场ES(维持畴生存所需的最小电场),开关将工作于延迟偶极畴模式.进而从理论和实验两方面指出半绝缘GaAs光电导开关是一种光注入畴器件,光生载流子的产生使得载流子浓度
与器件长度乘积满足产生空间电荷畴所需的条件.
【总页数】4页(P819-822)
【关键词】半绝缘GaAs光电导开关;耿效应;自激振荡;延迟偶极畴
【作者】田立强;施卫
【作者单位】西安理工大学应用物理系
【正文语种】中文
【中图分类】TN256
【相关文献】
1.半绝缘GaAs光电导开关体内热电子的光电导振荡特性 [J], 施卫;薛红;马湘蓉
2.用1064nm激光脉冲触发半绝缘Ga As光电导开关的奇特光电导现象(英文) [J],
施卫;戴慧莹;张显斌
3.高倍增GaAs光电导开关的光激发电荷畴模型(英文) [J], 施卫
4.GaAs光导开关lock-on模式的高倍增偶极畴模型 [J], 崔海娟;杨宏春;阮成礼;曾刚;吴明和
5.高倍增高压超快GaAs光电导开关中的光激发畴现象 [J], 施卫;梁振宪
因版权原因，仅展示原文概要，查看原文内容请购买。
高功率重频电化学HF激光器BULAEV V D;GUSEV V S;FIRSOV K N;KAZANTSEV S Yu;KONONOV I G;LYSENKO SL;MOROSOV Yu B;POZNYSHEV A N【期刊名称】《中国光学》【年(卷),期】2011(4)1【摘要】研制了高功率、高重频非链式HF激光器,并研究了脉冲模式和重频模式下在SF6的混合气中增加电极边缘电场强度而不使用其它措施即可实现自持体引发放电的可能性,得到了重复频率为20Hz,脉冲能量为67J,转换效率为3%的激光输出.【总页数】5页(P26-30)【作者】BULAEV V D;GUSEV V S;FIRSOV K N;KAZANTSEV S Yu;KONONOV I G;LYSENKO S L;MOROSOV Yu B;POZNYSHEV A N【作者单位】国家科学研究中心激光实验室,俄罗斯,弗拉基米尔地区;国家科学研究中心激光实验室,俄罗斯,弗拉基米尔地区;俄罗斯科学院普罗霍罗夫普通物理研究所,莫斯科,119991;俄罗斯科学院普罗霍罗夫普通物理研究所,莫斯科,119991;俄罗斯科学院普罗霍罗夫普通物理研究所,莫斯科,119991;国家科学研究中心激光实验室,俄罗斯,弗拉基米尔地区;国家科学研究中心激光实验室,俄罗斯,弗拉基米尔地区;国家科学研究中心激光实验室,俄罗斯,弗拉基米尔地区【正文语种】中文【中图分类】TN248.5【相关文献】1.高峰在值功率重频脉冲固体激光器 [J], 曹三松;王明秋2.放电引发的非链式高功率重复频率HF/DF激光器 [J], 黄珂;易爱平;朱峰;唐影;赵柳;马连英;冯国斌;叶锡生;刘晶儒3.高功率全固态紫外四倍频激光器 [J], 胡淼;金晶;李齐良;刘崇;葛剑虹;陈军4.高功率全固态激光器助力"先进制造"——"光纤输出高功率全固态激光器关键技术及应用"获国家技术发明奖二等奖 [J], 闫佳5.高功率二倍频、三倍频脉冲Nd：YAG激光器 [J], 邱文法;范畸康;陆祖康因版权原因，仅展示原文概要，查看原文内容请购买。
专利名称：自旋电子器件、磁存储器以及电子设备专利类型：发明专利
发明人：能崎幸雄
申请号：CN201980057546.1
申请日：20190904
公开号：CN112640088A
公开日：
20210409
专利内容由知识产权出版社提供
摘要：提供自旋电子器件、磁存储器以及电子设备，能够在不依赖于特定材料的情况下生成大自旋流。
自旋电子器件(1)具有导电层(2)、载流子迁移率或电导率比导电层(2)低的导电层(3)、以及导电层(2、3)之间的边界区域(4)。
边界区域(4)具有载流子迁移率或电导率的梯度，通过由该梯度产生的电子的速度场的旋转来生成自旋流。
申请人：学校法人庆应义塾
地址：日本东京都
国籍：JP
代理机构：北京三友知识产权代理有限公司
更多信息请下载全文后查看。
专利名称：MICROFLUIDIC SYSTEM WITH SINGLE DRIVESIGNAL FOR MULTIPLE NOZZLES发明人：Simon Dodd,Joe Scheffelin,Dave Hunt,MattGiere,Dana GRUENBACHER,Faiz SHERMAN申请号：US14976434申请日：20151221公开号：US20160107443A1公开日：20160421专利内容由知识产权出版社提供专利附图：摘要：The present disclosure is directed to a microfluidic die that includes a plurality of heaters above a substrate, a plurality of chambers and nozzles above the heaters, aplurality of first contacts coupled to the heaters, and a plurality of second contacts coupled to the heaters. The plurality of second contacts are coupled to each other and coupled to ground. The die includes a plurality of contact pads, a first signal line coupled to the plurality of second contacts and to a first one of the plurality of contact pads, and a plurality of second signal lines, each second signal line being coupled to one of the plurality of first contacts, groups of the second signal lines being coupled together to drive a group of the plurality of heaters with a single signal, each group of the second signal lines being coupled to a remaining one of the plurality of contact pads.申请人：STMicroelectronics, Inc.,STMICROELECTRONICS S.R.L.,STMicroelectronics International N.V.地址：Coppell TX US,Agrate Brianza IT,Amsterdam NL国籍：US,IT,NL更多信息请下载全文后查看。
第38卷第2期2024年3月山东理工大学学报(自然科学版)Journal of Shandong University of Technology(Natural Science Edition)Vol.38No.2Mar.2024收稿日期:20230210基金项目:山东省自然科学基金项目(ZR2020ME269);山东省海洋工程重点实验室开放基金项目(KLOE202005);山东省重点研发计划项目(2019GHY112076)第一作者:王春光,男,cgwang@;通信作者:郑润,男,408463461@文章编号:1672-6197(2024)02-0001-07海洋立管涡激振动的基本理论㊁研究方法㊁影响因素及抑振方式的研究综述王春光1,2,郑润1,李明蕾1,何文涛2,3(1.山东理工大学建筑工程与空间信息学院山东淄博255049;2.山东省海洋工程重点实验室,山东青岛266100;3.中国海洋大学工程学院,山东青岛266100)摘要:海洋立管是海洋油气开发平台的重要组成部分,而涡激振动研究是保障其正常工作的重要研究领域㊂本文从海洋立管涡激振动的基本理论㊁海洋立管涡激振动研究方法的发展㊁影响涡激振动的相关因素㊁涡激振动的监测和抑制方法四个方面对海洋立管涡激振动的相关研究进行综述㊂由前人工作可知,海洋立管涡激振动研究经历了试验研究㊁理论模型分析㊁计算流体力学方法的应用等多个阶段,而顶张力㊁洋流㊁波浪㊁支承条件㊁长细比㊁材料以及内流等均显著影响其涡激振动特征㊂为保障海洋立管在涡激振动情况下的正常工作,其抑振研究经历了由被动抑振到主动抑振,再到利用先进监测及预测手段采取特定抑振方式及时介入的发展过程㊂在将来,海洋立管监测控制系统必将发展为一个利用信息采集及处理平台,结合主动控制技术,实现海洋立管工作状态监测㊁故障发现以及主动控制的集中化㊁智能化系统㊂关键词:海洋立管;涡激振动;影响因素;涡激振动抑制中图分类号:P756.2文献标志码:AThe basic theory ,research methods ,affecting factors and suppression approaches of the vortex-induced vibration of marine risers :A reivewWANG Chunguang 1,2,ZHENG Run 1,LI Minglei 1,HE Wentao 2,3(1.School of Architectural Engineering and Spatial Information,Shandong University of Technology,Zibo 255049,China;2.Shandong Provincial Key Laboratory of Ocean Engineering,Qingdao 266100,China;3.College of Engineering,Ocean University of China,Qingdao 266100,China)Abstract :Marine riser is an important part of offshore oil and gas exploitation platform,and the research of vortex-induced vibration is an important research field to ensure its working situation.This paper re-views the related research of marine riser vortex-induced vibration in four aspects:the basic theory of ma-rine riser vortex-induced vibration,the history of research methods for marine riser vortex-induced vibra-tion,the relevant factors affecting vortex-induced vibration,and the monitoring and suppression methods of vortex-induced vibration.The researches on vortex-induced vibration of offshore risers have gone through stages such as experimental research,theoretical model analysis,application of computationalfluid dynamics methods.The top tension,ocean current,wave,support conditions,slenderness ratio,material and internal flow significantly affect its vortex-induced vibration characteristics.In order to㊀ensure the normal work of the riser under the condition of vortex-induced vibration,its vibration suppres-sion researches have developed from passive vibration suppression to active vibration suppression,and then to the use of advanced monitoring and prediction methods to take specialized vibration suppression methods on time.In the future,the marine riser monitoring and control system is foreseen to evolve into a centralized and intelligent system that uses information acquisition and processing system and combines active control technology to realize the monitoring of the working status,fault detection and active control for the marine risers.Keywords :marine riser;vortex induced vibration;influence factor;vortex-induced vibration suppression ㊀㊀自2021年以来,国际原油价格出现大幅上涨[1]㊂新冠疫情作为笼罩在全球经济发展上面的乌云开始散去,但经济复苏基础依然薄弱㊂被称为 工业血液 的石油是发展工业的重要动力,也是发展经济的重要资源㊂目前,陆地上的石油资源短缺的问题日益严重,据估算,地球上未被开采的海上石油储量的90%是在超过1000m 水深的海底地层下[2],而中国海岸线绵延辽阔,深海面积十分广阔,海上油气资源丰富,通过加快海洋油㊁气开发,中国必将逐步摆脱油气资源对外依赖㊂中国海洋石油勘探开发从沿海一隅到沿海集群作业,油气开发作业水深从100m 到如今的超3000m,海洋装备从最初的1艘钻井船发展到现在的61座钻井平台,实现了每年的海上原油产量从95000t 到48640000t 的跨越㊂特别是十八大以来,深水钻井平台 海洋石油982 ㊁海上移动式试采平台 海洋石油162 (图1)相继试验成功㊂中国的海洋油气勘探与开发进入了一个快速发展期,我们也提出了 走向深蓝 的战略口号,促进了海洋资源开发相关领域的研究㊂图1㊀ 海洋石油162 号无论采用何种海洋资源开采平台,海洋立管均是不可或缺的结构物,而80%的深水油气事故与立管的疲劳损伤相关㊂立管的疲劳损伤主要是由外部环境与立管相互作用而产生的涡激振动所引起[3-4],因此在海洋工程领域,开展了大量的复杂海况下海洋立管涡激振动影响因素及抑振方式的研究㊂1㊀海洋立管涡激振动的基本理论海洋立管作为海洋油气开发从海底将油气输送到海面平台的重要通道,是海洋油气开发的重要组成构件㊂海洋立管在洋流作用下,在立管两侧尾流区发生交替泄涡,漩涡的生成和泄放相关联,立管受到横流向及顺流向的脉动水压力作用后将引发振动㊂在海流引发交替泄涡导致立管振动的同时,立管振动反过来又会影响海流的尾流结构,进而改变立管上的脉动水压力分布,这便是海洋立管的涡激振动现象(VIV)㊂涡激振动将导致立管疲劳破坏,不仅影响工程进展,而且可能产生严重的环境灾害,因此受到各国学者的广泛重视㊂海洋立管的涡激振动源于Von Kármán 发现的涡街效应[5],其受力原理和数值模拟如图2及图3所示㊂图2㊀立管在涡街作用下受力示意图图3㊀数值模拟卡门涡街[6]2山东理工大学学报(自然科学版)2024年㊀对圆柱体绕流,交替脱落的单个漩涡的脱落频率f与绕流流体的速度v成正比,与立管直径d成反比,即得公式(1)[7]:f=Sr(v/d),(1)式中Sr是斯特劳哈尔数㊂斯特劳哈尔数主要与雷诺数有关㊂雷诺数的物理意义是惯性力与黏性力的比值㊂Re=ρVLˑVLμˑVL =ρL3㊃(V2/L)μ(V/L)㊃L2=ma(惯性力)τA(粘性力),(2)通过公式(2)的变形就可以直观的得出雷诺数Re 的物理意义,雷诺数越小液体粘滞力影响大于惯性的影响,雷诺数越大液体惯性影响大于黏滞力的影响㊂当雷诺数数值达到300~3ˑ105时,斯特劳哈尔数数值近似于常数值(0.21);当雷诺数数值达到3ˑ105~3ˑ106时,有规律的漩涡脱落现象便不再存在;当雷诺数数值大于3ˑ106时,卡门涡街又会出现,这时斯特劳哈尔数约为0.27[8](图4)㊂图4㊀不同雷诺数液体绕柱流动状态当涡激振动的频率与物体的固有频率相接近,就会引起共振,甚至使物体损坏㊂除了雷诺数会影响涡激振动的出现外,圆柱体的质量比也会影响相同来流下涡激振动的振幅大小[9-10],影响涡激振动对立管损伤的程度㊂当来流冲击立管圆柱体产生涡激振动后,会使立管在顺流向和横流向两个方向因为受力而产生震动,这两个方向上的力的大小可利用公式(3)[11]计算:F x=12C dρDU2,F y=12C lρDU2,(3)式中:F x㊁F y分别为立管受到的阻力和升力,D为圆柱直径,ρ为流体密度,C d㊁C l分别为阻力系数和升力系数,U为流体速度㊂由此可见,相关研究需记录涡激振动作用下立管顺流向㊁横流向两个方向上的相关数据(图5)㊂图5㊀双向受力监测2㊀海洋立管涡激振动研究方法的发展自卡门涡街现象被发现以来,海洋立管的涡激振动研究经历了从实验研究㊁理论模型分析㊁计算流体力学方法的应用等多个阶段㊂首先Feng通过圆柱体风洞试验验证了横向振动为主要振动的涡激振动的存在,Ferguson等[12]通过使用声学液位压力传感器的原始设计,发现了圆柱体漩涡激发振荡的表面和尾流现象㊂自此之后以海洋立管为代表的圆柱体的涡激振动特征研究不断通过水槽(水池)模型试验得以完成[5,7]㊂实验研究之外,各国学者还提出了经验模型以求解立管的涡激振动问题㊂首先,Hartlen等[8]开创性地建立了尾流振子模型的数学表达式;随后,各国学者通过数十年的努力和研究对尾流振子模型不断地进行改进和发展㊂Skop 等[11,13]对此尾流振子模型进行扩展,将其应用到柔性细长柱体的涡激振动研究中㊂Kim等[14]以及Facchinetti等[15]则对此进行了进一步的修正和改进㊂而郭海燕等[16]则考虑了立管内流对立管涡激振动的影响㊂近年来,随着计算和存储技术的发展,越来越多的人开始转向利用计算流体动力学(CFD)技术解决VIV问题㊂通常CFD模型可以分为四类:离散涡方法(DVM),雷诺平均N-S方程(RANS)方法,大涡模拟(LES)方法以及N-S方程直接模拟(DNS)方法㊂3㊀影响涡激振动的相关因素在海洋油气开发过程中,海洋立管从海底输送到海面的混合体成分包括油㊁气㊁水以及沙石等等,是复杂的混合物,在超长立管管道内输送由于内外3第2期㊀㊀㊀㊀㊀王春光,等:海洋立管涡激振动的基本理论㊁研究方法㊁影响因素及抑振方式的研究综述流耦合作用下造成明显的周期性和压力波动特性的不稳定现象,以至于引起立管的振动[17-18]㊂为研究立管涡激振动的影响,考虑多因素影响的预测模型[3]以及考虑海洋环境参数的涡激振动特征研究[19]是必不可少的㊂图6展示了海洋立管配置情况,由此可见,海洋立管系统复杂多变,需考虑的设计参数及环境因素多样㊂图6㊀水下海洋立管配置[20]现在关于海洋立管的涡激振动研究正从之前的单因素研究发展到现如今的多因素研究㊂使海洋立管产生涡激振动的主要原因包括立管本身的材料特性㊁洋流流速㊁顶部张力㊁边界条件以及波浪等㊂葛士权等[21]通过利用ANSYS 软件进行了多因素影响下的海洋立管涡激振动的三维计算流体动力学模拟(图7)㊂大长细比是实际工程中很明显的一个特点,Wang 等[22]针对大长细比立管模型在洋流作用下的涡激振动响应进行了实验研究㊂关于顶张力对立管在涡激振动中频率的影响方面,Yang [23]通过实验得出预张力的增加,组合激励下的顶部张紧提升管(TTR)的不稳定性会被抑制,但抑制效果的提升与预张力增加不成比例㊂李文华等[24]将立管简化为典型的Euler-Bernoulli 弹性梁模型,根据传递矩阵理论得出表观重力和立管内外侧压力差引起的海洋立管轴向拉力的变化可影响立管本身固有频率的结论㊂张永波等[25]研究了顶张力对立管涡激振动的影响㊂柳军等[26]通过实验得出结论,在均匀流速条件下,立管的振动频率在顺流向条件下是横流向条件下的两倍,因此两个方向的影响相差不大,应该同时考虑两个方向的影响㊂殷布泽等[27]通过总结过往的海洋立管涡激振动实验提出要更加注重波浪对于海洋立管涡激振动的影响㊂李莹等[28]针对边界条件进行研究,对立杆端部应用铰接固接两种边界支座进行研究,发现其他参数相同时,两端铰接时立管的震动幅度大于立管两端固接时的震动幅度,Gao 等[29]通过数值分析的方式研究得出在一定范围内立管长细比(L /D)越小,不同边界条件下的VIV 位移差异越大㊂巫志文等[30]的研究中考虑建立随机波浪和涡流激励联合作用下海洋立管动力响应的数学分析模型,通过此模型进行随机波浪对立管涡激振动的影响进行研究㊂Wang 等[31]进行了多因素实验,研究了立管材料㊁流速㊁顶张力和边界条件几个因素综合对立杆涡激振动的影响,但是并没有结合波浪的影响(表1)㊂图7㊀数值模拟海洋立管变形情况[21]表1㊀Wang 等进行多因素实验的工况[31]4山东理工大学学报(自然科学版)2024年㊀㊀㊀通过结合新的实验方法[32],崔阳阳等[33]进行了多参数耦合作用下的海洋立管涡激振动实验,并基于灰色理论[34]实现了影响因素重要性排序,但该实验并没有考虑周期性波浪对于海洋立管涡激振动的影响㊂4㊀涡激振动的监测和抑制方法为抑制海洋立管由涡激振动引起的疲劳损伤,学者们在涡激振动抑制方面展开了广泛的研究㊂Rodriguez [35]通过改变物体形状和尾翼形状设计进行实验,探究形状对涡激振动的影响,但此实验的实验对象与环境模拟与海洋立管相差很大(图8)㊂图8㊀Rodriguez 实验试件与实验效果[35]Owen 等[36]进行了圆形柱体在不同雷诺数范围的涡激振动实验,并发现施加质量块后涡激振动可减少47%㊂娄敏等[37]通过实验发现在锁振状态下,通过敲击立管打破流体与结构之间的耦合关系可以达到抑制涡激振动的效果㊂王海青等[38]提出了在立管外部构造三种不同形状来达到抑制涡激振动的效果并进行了实验㊂Gao 等[29]分析模拟得出对于具有小长径比的圆柱体,不同边界条件下的VIV 位移存在明显差异㊂吴仕鹏等[39]通过在立管外添加螺旋板来研究其对于涡激振动的抑制效果,结果表明在高雷诺数来流情况下该装置能大幅降低立管疲劳风险㊂娄敏等[40]采用仙人掌形状截面的立管,通过数值分析得出在约化速度4~8范围能降低横顺两方向的振动幅值㊂李子丰等[41]采用羽翼状外包进行实验研究,发现加装该结构能有效减少圆柱后涡旋的产生㊂翟云贺等[42]提出一种双组双螺旋的装置,实验表明在当来流为对称流时,双组双螺旋装置能有效抑制涡激振动㊂沙勇等[43]通过实验对螺旋列板的几何参数对于涡激振动影响进行研究,为以后的相关研究提供了宝贵数据(图9)㊂齐娟娟等[44]提出了一种口型截面的三螺头螺旋导板,并进行了风洞试验,实验得出该装置对于大质量阻尼比圆柱有较好的抑制涡激振动的效果(图10)㊂睢娟等[45]利用外包毛绒进行风洞试验,得出绒毛长度增加,抑制效果越好的结论㊂王伟等[46]提出一种安装旋翼的方案,通过数值模拟得出随着旋翼旋转速度增加立管振幅减小㊂周阳等[47]利用带螺旋侧板的立管模型进行试验,结果表明该装置能够扰乱尾流涡旋,抑制涡激振动㊂图9㊀含有保温层的立管螺旋列板的横截面[43]图10㊀试验模型安装及螺旋导板模型结构示意图[44]除了通过改变立管外包形状进行被动抑制,近些年也有学者提出通过主动对立管施加作用来进行主动抑制㊂Yang 等[23]通过实验得出通过增加顶张力可以对涡激振动进行抑制,但抑制效果与力的增加成非线性关系㊂Wang 等[48]利用雷诺数为100的合成射流进行涡激振动的抑制㊂Chen 等[49]提出利用吸流法进行涡激振动的抑制㊂赵瑞等[50]提出通过施加端部激励来进行涡激振动的抑制,实验结果表明,频率比较小时,轴向力激励能降低涡激振动位移㊂Zhang 等[51]针对具有顶部张力的柔性船舶立管系统控制立管振动进行研究,实验表明在适当的参数选择下系统具有良好性能㊂随着信息技术的发展,将计算机信息技术与实际工程结合成为近年学者们研究的方向,Wong 等[52]提出可以利用神经网5第2期㊀㊀㊀㊀㊀王春光,等:海洋立管涡激振动的基本理论㊁研究方法㊁影响因素及抑振方式的研究综述络结合使用Matlab 中的LHS 技术预测TTR 短期涡激振动疲劳损伤的简化方法㊂高喜峰等[53]提出要利用BP 神经网络预报柔性立管涡激振动横流向及顺流向位移和频率响应,随后Yu 等[54]以及Yan 等[55]利用了基于自适应神经网络的边界控制方法,以预测振动风险,从而及时采取对应抑振措施(图11)㊂图11㊀BP 神经网络结构5㊀结束语开发海洋油气资源已经成为中国缓解油气对外依赖的重要途径,而海洋立管作为海洋资源开发平台中不可或缺的重要组成部分,其涡激振动导致的疲劳破坏是重点研究和关注的领域㊂本文从海洋立管涡激振动的基本理论㊁海洋立管涡激振动研究方法的发展㊁影响涡激振动的相关因素㊁涡激振动的监测和抑制方法四个方面对海洋立管涡激振动的相关研究进行综述,由综述可知:1)海洋立管的涡激振动研究方法经历了试验现象研究到理论与经验公式创建再到借助高性能计算机的计算流体力学研究的发展;同时,可以发现影响海洋立管涡激振动特征的因素包括顶部张力㊁海洋洋流(流速㊁流向等)㊁波浪特征(波高㊁周期等)㊁支承条件㊁立管长细比㊁立管材料以及内流的影响等㊂2)对于海洋立管涡激振动特征的研究正由单因素研究向多因素耦合研究发展,但目前多因素耦合作用下的相关研究仍显不足㊂为了更加贴合实际工程,实现更安全㊁更高效的海洋油气的开发,多因素耦合作用下的海洋立管涡激振动研究将是未来研究的重要方向之一㊂3)在海洋立管涡激振动抑制方法的研究中,研究者们发现改变立管质量㊁破除耦合关系㊁改变立管及其附加物形状㊁引入主动抑振手段等均可有效改善立管的涡激振动现象,其抑振研究经历由被动抑振到主动抑振再到利用先进监测及预测手段采取特定抑振方式及时介入的发展㊂4)随着信息技术的发展,海洋立管监测控制系统将发展为利用信息采集及处理平台,结合主动控制技术实现其工作状态监测㊁故障发现以及主动控制的集中化㊁智能化系统㊂参考文献:[1]IEA.Oil 2021:Analysis and forecast to 2026[R].Paris:Interna-tional Energy Agency,2021.[2]IEA.Offshore energy outlook[R].Paris:International Energy A-gency,2018.[3]LIU G,LI H,QIU Z,et al.A mini review of recent progress on vor-tex-induced vibrations of marine risers [J].Ocean 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a r X i v :c o n d -m a t /0209462v 1 [c o n d -m a t .m e s -h a l l ] 19 S e p 2002Charged vortices in superfluid systems with pairing of spatially separated carriersS.I.ShevchenkoB.I.Verkin Institute for Low Temperature Physics and Engineering National Academy of Sciences of Ukraine,Lenin av.47Kharkov 61103,Ukraine(Dated:February 1,2008)It is shown that in a magnetic field the vortices in superfluid electron-hole systems carry a real electrical charge.The charge value depends on the relation between the magnetic length ℓB and theBohr radiuses of electrons a e B and holes a hB .In double layer systems at filling factors νe =νh =νand for a e B ,a hB ≫ℓB the vortex charge is equal to the universal value νe .PACS numbers:03.75.Fi,05.30.Jp,72.20.HtIt is generally believed,that the vortices in supercon-ductors are connected with an applied magnetic field,while the magnetic field does not have any influence on the properties of the vortices in electrically neutral su-perfluid systems.The aim of this letter is to show that in superfluid systems subjected by a magnetic field the vortices will have a real electrical charge (the compensat-ing charge of the opposite sign will appear on the surface of the system).In general case the charge of the vortices takes a fractional value.For the first time the fractional charge of the vortices was predicted by Laughlin [1]for the two-dimensional electron gas in a quantized magnetic field.Then,it was established in Ref.[2,3],that in double layer electron systems with the half-filling of the lowest Landau levels in each layer the vortices should carry the charge equals to ±e/2(here and below e is the absolute value of the electron charge).We will show that in any superfluid system the mag-netic field results in an appearance of the vortex charge proportional to the polarizability of the particles and in-verse proportional to their effective mass.The estimates show that for reachable values of magnetic fields the vor-tex charge is unobservable small one in superfluid phases of He isotopes and in Bose gases of alkali metals,while it can be of order of the electron charge in superfluid systems with pairing of spatially separated electrons and holes.The authors of Ref.[4]call the possibility of the electron-hole pair superfluidity in question based on the fact that the interband transitions fix the phase of the or-der parameter and result in a transition into a dielectric state.But it was established in Refs.[5,6]that the inter-diction on the electron-hole superfluidity can be removed in systems,where the spatially separated electrons and holes are coupled.In these systems the interband transi-tions coincide with the interlayer ones and usually they are exponentially small.The superfluid state of the pairs with spatially separated components has both the super-fluid and superconducting features.The superfuid flow of such electron-hole pairs is accompanied with real su-percurrents flowing in opposite directions.Therefore,we will call these systems the condenser superconductors.In Refs.[5,6]the pairing of a conducting band elec-tron from the one layer with a valence band hole from the other layer was considered.Then in a number of theoret-ical papers [2,3,7,8,9,10]it was shown a possibility of superfluidity of pairs composed from spatially separated electrons and holes belonging to the conducting band.This possibility is realized in double layer electron sys-tems in a magnetic field normal to the layers for the case of the total filling factor νT =ν1+ν2=1.During almost 10years there were many efforts to observe the condenser superconductivity experimentally [11,12,13,14].Now it seems that these effort have been crowned with success [15,16].The principal result can be obtained from general con-sideration which does not imply a concrete form of the Hamiltonian.Let us consider a superfluid system sub-jected with crossed electric E and magnetic B fields.Let E is the density of the energy of the system,and Πis the density of its generalized momentum.Note,that the values of E and Πdo not include the energy and the mo-mentum of the external fields that polarize the system.We are interesting in a relation between the momentum density Πand the dipole momentum density P .To es-tablish this relation it is convenient to consider the frame of reference,in which the electric field is equal to zero.The velocity of that frame relative to the lab frame is equal tou =cE ×B2.(3)2Hereρis themassdensity.Expressing themomentumΠ0in Eq.(3)in terms of the momentumΠwe obtain E=E0(Π−ρu)+Πu−ρu2∂Π=v,∂EcP×B.(6)In general case the kinematic momentumρv is of order of the generalized momentumΠ.But,as it is shown be-low,for the condenser superconductors in a strong mag-neticfield the kinematic momentum is much smaller than the generalized one.Consequently,in a strong magnetic field the termρv in Eq.(6)can be omitted.Taking into account,that in the superfluid systemΠ=n ∇ϕ,where n is the density of the particles(we consider the temper-ature T=0),andϕis the phase of the order parameter, we obtain from Eq.(6)the following relationn ∇ϕ=−1cdiv2P,(8) where div2P is the two-dimensional divergence.of the vector P.This quantity taken with its sign changed is equal to the polarization charge densityρpol.On the other hand,the left hand side of Eq.(8)is nonzero only in case,when the quantized vortices exist in the system. Thencurl z∇ϕ=2π iδ(r−r i)n i,(9)where n i=±1the upper(low)sign corresponds to the vortices rotating in the counter-clockwise(clockwise)di-rection,and the summation is over the vortex centers. Integrating the both parts of Eq.(8)over an arbitrary area,for vortices of the same sign onefinds±2π nN v=H c Q v.(10)Here N v is the number of the vortices in the area S,and Q v is their charge.It follows from this,that vortex charge is equal toq≡Q vBn=±2πeℓ2B n.(11)In the case of the electron-hole pairing in the lowest Lan-dau level,the density of the pairs n is related with thefilling factorsνe=νh=νby the formulaν=2πℓ2B n.Thus,in strong magneticfields in the superfluid phasethe quantized vortices carry an electrical charge q=±νe.To clarify how general is the result obtained let us an-alyze the behavior of the condenser superconductor in astrong magneticfield perpendicular to the layers at smallfilling factorsν,when the electron-hole pair gas can beconsidered as a weakly interacting Bose gas.Let us con-sider two2D conducting layers separated by the dielectriclayer of the width d with the electron carriers in one layerand the hole carriers in the adjacent layer.We considerm h≫m e.In a strong magneticfield the large differ-ence of the masses m e and m h may result in a situation,when the electron Bohr radius a e B=ε 2/m e e2is muchlarger then the magnetic lengthℓB=(c /eB)1/2,andthe hole Bohr radius a h B=ε 2/m h e2can be smaller orlarger thenℓB.In this case the energy spectrum of thebounded electron-hole pair,which is formed due to theCoulomb interaction between spatially separated carri-ers,was found in[17].The part of the pair energy de-pending on the momentum of the pairπand the velocityu is equal to∆E=π2M∗uπ−1M∗m h u2.(12)Here M∗=M B+m h,the pair effective mass,M B,the”magnetic mass”M B=42πε 2√ℓB.(13)Introducing the pair polarizabilityα(B)=M Bc2√2M∗ π+α(B)E×B2E2.(15)Analogous expression was obtained in[18]for an electri-cally neutral atom in crossedfields for the case of smallmagneticfields.In that case Eq.(15)contains the zeromagneticfield polarizability of the atomα(0)instead ofα(B)and the mass of the atom M instead of the massof the pair M∗.Replacing the momentumπwith the operator−i ∇,from Eq.(15)we obtain the Hamiltonian of the electron-hole pairs.In the low density limit,when the size ofthe pair is much smaller then the distance between thepairs and the exchange effects are inessential,the pairscan be considered as true bosons.At low temperaturesthe rarefied Bose gas should form a superfluid state.The3superfluid phase can be described by the order parameter Ψ.The order parameter satisfies the equationi∂Ψ2M ∗−i ∇+α(B )E ×B 2E 2Ψ+γ|Ψ|2Ψ.(16)The last term in the r.h.s.of Eq.(16)describes the in-teractionbetweenthepairs.One canshow thatin thethe limitd ≪ℓB the interaction constant is equal to γ=(π/2)3/2e 2d 2/εℓB .The vanishing of the interaction constant at d =0is the consequence of the exact compen-sation of the Coulomb forces between the pairs (compare with [19]).Presenting the order parameter in the form Ψ=|Ψ|e iϕ(r ),we obtain from Eq.(16)the velocity of the superfluid componentv s =1c.(17)To obtain the dipole momentum of the unit area P we take into account that the r.h.s.of Eq.(16)is the variational derivative over Ψ∗(r )of the energy functional of the Gunzburg-Landau type for superconductors.The derivative of that functional over the electric field E taken with the opposite sing is P :P =α(B ) 1−M BM ∗c ∇ϕ×B|Ψ|2.(18)The expression (18)can be rewritten in the formP =α(B ) E +1M ∗div 2E +i2πBM ∗cα(B )n.(21)Eq.(21)yields the vortex charge for the electron-hole double layer systems in an arbitrary magnetic fields.The same result is valid for the electron-electron double layer system with the substitution M ∗=M B +2m e .In weak magnetic fields (ℓB ≫a e B )the polarizabilityα=γ(a e B )3,where γ∼1,and the effective mass M ∗≃m h +m e ≃m h .Then,the vortex charge is equal toq =±2πγℓB2a e B a hB ne.(22)In high magnetic fields (a e B ≫ℓB a hB )using Eq.(14)for α(B )one obtainsq =±2πℓ2B nM BM ∗νe.(23)Finally,in ultra high fields (a hB ≫ℓB )the effective mass M ∗=M B (1+√cBE ×d l .(24)Here N v is the number of the vortices inside the contour (we consider the vortices of the same vorticity).It fol-lows from Eq.(24),that the velocity v s can be reduced4 under the appearance of the vortices-in such a way welower the kinetic energy of the system.When the vortexdistribution is considered as a continuous one,the vortexdensity n v(r)can be introducedN v= n v(r)d r.(25)Putting the r.h.s.of Eq.(24)to zero wefind from Eqs.(24)and(25)the relationn v(r)=α(B)Bρi+1−ρi.(28)Eqs.(26)-(28)allow tofind the values of N i andρi upto a factor of order of unity.A macroscopic number of the vortices with equal vor-ticites can also emerge in the absence of the electricfield.It is realized when besides the uniformfield B z there isan extrafield Bτwith div2Bτ=0(Bτis parallel to theplane of the structure).Indeed,one can show(comparewith[20])that in thefield Bτthe energy of the pair ofspatially separated electron and hole is equal toE=1cˆz×Bτ)2.(29)One can see that energy(29)differs from the expressions(15)only by that the induced dipole momentumα(B)Eis replaced with the spontaneous momentum edˆz.There-fore,the dipole momentum of the unit area can be ob-tained from Eq.(19)replacing the induced momentumwith the spontaneous one.Then,taking the divergenceof P,wefindρpol(r)=−α(B)Bncdiv2Bτ+ i2π n iδ(r−r i) .(30)It follows from this expression that in this case the vortexcharge is equal the value found above and in the continu-ous limit the vortex density is n v(r)=(ed/2π c)div2Bτ.At nonzero temperatures the charged vortices willemerge in condenser superconductors in afluctuationway,in similarity with the same phenomena in a thin He-IIfilm.The circumstance that the vortices are chargeddoes not influence in thefirst approximation on the ther-modynamic features of the system.It is connected withthat the Coulomb correction to interaction between thevortices falls down much faster(by the power law)thenbare logarithmic interaction between them.The last one,as is well known,results in a Kosterlitz-Thouless 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