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| 1 | Third generation of vortex identification methods:Omega and Liutex/Rortex based systems显示文摘A vortex is intuitively recognized as the rotational/swirling motion of fluids,but a rigorous and universally-accepted definition is still not available.Vorticity tube/filament has been regarded equivalent to a vortex since Helmholtz proposed the concepts of vorticity tube/filament in 1858 and the vorticity-based methods can be categorized as the first generation of vortex identification methods.During the last three decades,a lot of vortex identification methods,including 0,A,and Aci criteria,have been proposed to overcome the problems associated with the vorticity-based methods.Most of these criteria are based on the Cauchy-Stokes decomposition and/or eigenvalues of the velocity gradient tensor and can be considered as the second generation of vortex identification methods.Starting from 2014,the Vortex and Turbulence Research Team at the University of Texas at Arlington(the UTA team)focus on the development of a new generation of vortex identification methods.The first fruit of this effort,a new Omega(/2)vortex identification method,which defined a vortex as a connected region where the vorticity overtakes the deformation,was published in 2016.In 2017 and 2018,a Liutex(previously called Rortex)vector was proposed to provide a mathematical definition of the local rigid rotation part of the fluid motion,including both the local rotational axis and the rotational strength.Liutex/Rortex is a new physical quantity with scalar,vector and tensor forms exactly representing the local rigid rotation of fluids.Meanwhile,a decomposition of the vorticity to a rotational part namely Liutex/Rortex and an anti-symmetric shear part(RS decomposition)was introduced in 2018,and a universal decomposition of the velocity gradient tensor to a rotation part(7?)and a non-rotation part(NR、was also given in 2018 as a counterpart of the traditional Cauchy-Stokes decomposition.Later in early 2019,a Liutex/Rortex based Omega method called Omega-Liutex,which combines the respective advantages of both Liutex/Rortex and Omega methods,was developed.And a latest objective Omega method,which is still under development,is also briefly introduced.These advances are classified as the third generation of vortex identification methods in the current paper.To elaborate the advantages of the third-generation methods,six core issues for vortex definition and identification have been raised,including:(1)the absolute strength,(2)the relative strength,(3)the rotational axis,(4)the vortex core center location,(5)the vortex core size,(6)the vortex boundary.The new third generation of vortex identification methods can provide reasonable answers to these questions,while other vortex identification methods fail to answer all questions except for the approximation of vortex boundaries.The purpose of the current paper is to summarize the main ideas and methods of the third generation of vortex identification methods rather than to conduct a comprehensive review on the historical development of vortex identification methods. | Chaoqun Liu Yi-sheng Gao Xiang-rui Dong Yi-qian Wang Jian-ming Liu Yu-ning Zhang Xiao-shu Cai Nan Gui | 2019 | Journal of Hydrodynamics2019，31，2： | 82 |
| 2 | A Survey of Unbalanced Flow Diagnostics and Their Application显示文摘This paper presents an extensive survey of the most commonly used tools for diagnosing unbalanced flow in the atmosphere, namely the Lagrangian Rossby number, Psi vector, divergence equation, nonlinear balance equation, generalized omega-equation, and departure from fields obtained by potential vorticity (PV) inversion. The basic thoery, assumptions as well as implementation and limitations for each of the tools are all discussed. These tools are applied to high-resolution mesoscale model data to assess the role of unbalanced dynamics in the generation of a mesoscale gravity wave event over the East Coast of the United States. Comparison of these tools in this case study shows that these various methods agree to a large extent with each other though they differ in details. | Fuqing Zhang Steven E. Koch Christopher A. Davis and Michael L. Kaplan | 2000 | Advances in Atmospheric Sciences2000，17，2： | 22 |
| 3 | 非API标准Big Omega特殊螺纹接头连接性能数值分析显示文摘以德国非API标准的Big Omega特殊螺纹接头作为研究对象,应用有限元软件ANSYS建立计算力学模型,模拟套管柱接头行为,通过改变螺纹参数(高度、锥度等),计算得出各扣牙相应的最大法向接触应力与最大接头Mises应力。分析螺纹参数变化对扣牙所受应力的影响规律,从而得到Big Omega接头螺纹参数的改变对套管接头连接性能的影响规律,进而为套管柱接头特殊螺纹扣型的选择提供依据,为套管柱设计提供更为有效的参考。 | 许志倩 闫相祯 杨秀娟 | 2009 | 石油矿场机械2009，38，6： | 18 |
| 4 | Vortex identification methods in marine hydrodynamics显示文摘In this paper,several commonly used vortex identification methods for marine hydrodynamics are revisited.In order to extract and analyse the vortical structures in marine hydrodynamics,the Q,λ2-criterion and modified normalized Liutex/RortexΩR method are utilized for vortex identification for propeller open water test,ship drag test,ship propeller-rudder interaction,VIV of a marine riser and VIM of a Spar platform.The limitation of Q andλ2-criterion is discussed.The Liutex/RortexΩR method is promising for convenient and accurate vortex identification and visualization.However,care should be taken when choosing the small parameter b0 forΩR.We proposed recommended values of b0 for marine hydrodynamic problems. | Wei-wen Zhao Jian-hua Wang De-cheng Wan | 2020 | Journal of Hydrodynamics2020，32，2： | 14 |
| 5 | “女性向·耽美”文化显示文摘【女性向/男性向/女频/男频】
男生一般不看女性向小说,但是很多女生爱看男性向小说呢!天呐,男朋友昨天看了我手机里的女频小说,居然很感兴趣的样子……现在问题来了,他让我给他推荐看文的网站,我应该推起点还是晋江?《全职高手》完全可以算作是女性向嘛,不管蝴蝶蓝(作者)承认不承认。 | 郑熙青 肖映萱 林品 | 2016 | 天涯2016，，3： | 14 |
| 6 | Laser-direct-drive program: Promise, challenge, and path forward显示文摘Along with laser-indirect(X-ray)-drive and magnetic-drive target concepts,laser direct drive is a viable approach to achieving ignition and gain with inertial confinement fusion.In the United States,a national program has been established to demonstrate and understand the physics of laser direct drive.The program utilizes the Omega Laser Facility to conduct implosion and coupling physics at the nominally 30-kJ scale and lasereplasma interaction and coupling physics at the MJ scale at the National Ignition Facility.This article will discuss the motivation and challenges for laser direct drive and the broad-based program presently underway in the United States. | E.M.Campbell V.N.Goncharov T.C.Sangster S.P.Regan P.B.Radha R.Betti J.F.Myatt D.H.Froula M.J.Rosenberg I.V.Igumenshchev W.Seka A.A.Solodov A.V.Maximov J.A.Marozas T.J.B.Collins D.Turnbull F.J.Marshall A.Shvydky J.P.Knauer R.L.McCrory A.B.Sefkow M.Hohenberger P.A.Michel T.Chapman L.Masse C.Goyon S.Ross J.W.Bates M. Karasik J.Oh J.Weaver A.J.Schmitt K.Obenschain S.P.Obenschain S.Reyes B.Van Wonterghem | 2017 | Matter and Radiation at Extremes2017，2，2： | 10 |
| 7 | 沉管隧道用橡胶止水带研究现状及工程应用显示文摘综述了橡胶止水带的研究现状及工程应用情况,对当前沉管隧道等大型工程中常用的GINA,OME-GA可注浆及膨胀式橡胶止水带进行了简述。对橡胶止水带胶料的耐久性等特性、寿命预测和破坏机理进行了分析论述。 | 陈娅玲 张保生 王三孟 刘清亭 宋春华 郭红锋 | 2012 | 特种橡胶制品2012，33，4： | 9 |
| 8 | Comparisons and analyses of vortex identification between Omega method and Q criterion显示文摘The present paper presents comparisons of the vortex identification between the Omega method and the Q criterion based on the data of a classical flow.From the comparisons of the vortex structure together with the flow statistics,some important conclusions are drawn on the validity of the two methods,as follows.The Omega method can identify various kinds of vortices with different intensities(e.g.,the strong vortex,the medium vortex and the weak vortex).For the Q criterion,due to the subjective threshold selection,only the strong vortex with weak deformations could be identified.Finally,some emerging topics related with the advanced vortex identification methods are briefly discussed. | Yu-ning Zhang Xiao-yu Wang Chaoqun Liu | 2019 | Journal of Hydrodynamics2019，31，2： | 8 |
| 9 | 番木瓜proteinase omega基因启动子的克隆及功能初步研究显示文摘采用PCR技术从番木瓜基因组中克隆了proteinase omega基因的部分序列及其5′侧翼序列。序列分析表明,克隆到的基因序列与GenBank中的序列同源性为96%,长1039bp的5′端侧翼序列在GenBank数据库中没有同源片段。预测5′端侧翼序列有两处基础启动子区域,转录起始位点(TSS)分别为是A,T。在基础启动子区域都存在TATA-box,上游发现多处CAAT-box,G-box,I-box等顺式作用元件和AT富含区。构建了植物表达载体并用基因枪轰击番木瓜的叶组织,GUS基因瞬间表达结果表明,该长1039bp的5′端侧翼序列具有驱动GUS基因在乳管中表达的功能。该启动子的发现对进一步研究启动子的功能和开发番木瓜作为生物反应器具有重要意义。 | 杨英军 周鹏 | 2005 | 云南植物研究2005，27，5： | 8 |
| 10 | 一次北方暴雨的Q矢量诊断分析研究显示文摘考虑水汽相变的凝结潜热作用,引入广义位温,发展了包含广义位温的Q矢量,并在此基础上推导了非地转湿大气Omega方程。(1)包含广义位温的Q矢量是Omega方程的唯一强迫项,由拟涡度伸展矢量、锋生矢量和非绝热加热梯度等三项构成。(2)利用包含广义位温的Q矢量对一次北方夏季暴雨进行诊断分析,发现包含广义位温的Q矢量对降水区的垂直运动结构有良好指示意义,可以综合表征次级环流、锋生和锋消、大尺度和中尺度强迫等多种物理因素,而这些均是影响暴雨发生发展的重要因素,因而包含广义位温的Q矢量及其散度与强降水的发生发展密切相关。(3)利用美国全球预报系统24 h预报场对包含广义位温的Q矢量散度进行计算,结果表明预报的Q矢量散度在时间和空间上与观测6 h降水联系紧密,根据预报的Q矢量散度的异常能够判断降水的可能落区。 | 冉令坤 李振 张雅斌 齐彦斌 | 2019 | 暴雨灾害2019，38，1： | 6 |
| 11 | 谷胱甘肽硫转移酶Omega家族的研究进展显示文摘 | 梁冰 张爱华 | 2006 | 中国公共卫生2006，22，12： | 5 |
| 12 | Antisense-mediated Depletion of Tomato Endoplasmic Reticulum Omega-3 Fatty Acid Desaturase Enhances Thermal Tolerance显示文摘An endoplasmic reticulum-localized tomato ω-3 fatty acid desaturase gene(LeFAD3) was isolated.The antisense tomato plants were obtained under the control of the cauliflower mosaic virus 35S promoter(35S-CaMV).Northern blot analysis confirmed that the expression of LeFAD3 was inhibited in the tomato genome.Levels of 18:3 decreased and correspondingly levels of 18:2 increased in total lipids of leaves and roots.After heat stress,the fresh weight of the aerial parts of antisense transgenic plants was higher than that of the wild type(WT) plants.The membrane system ultrastructure of chloroplasts in leaf cells and all of the subcellular organelles in the root tips of transgenic plants remained more intact than those of WT.Relative electric conductivity increased less in transgenic plants than in WT.Under heat stress,the maximal photochemical efficiency of photosystem II(Fv/Fm) and the O2 evolution rate decreased more in WT than in transgenic plants.These results suggested that the depletion of LeFAD3 increased the saturation of fatty acids and alleviated high temperature stress. | Hua-Sen Wang Chao Yu Xian-Feng Tang Li-Yan Wang Xun-Chun Dong Qing-Wei Meng | 2010 | Journal of Integrative Plant Biology2010，52，6： | 4 |
| 13 | 脂质体阿霉素和卡培他滨对老年转移性乳腺癌的疗效相当显示文摘至今,关于老年转移性乳腺癌(metastatic breast cancer,MBC)化疗药物的前瞻性数据仍然较少。近日,荷兰乳腺癌研究小组BOOG进行了一项多中心Ⅲ期OMEGA研究,比较脂质体阿霉素(pegylated liposomal Doxorubicin,PLD)与卡培他滨一线治疗≥65岁MBC患者的疗效和安全性。 | 温灵珠 | 2014 | 循证医学2014，14，2： | 4 |
| 14 | 拳击运动员心率变异性、心电图变异及Ω电位各指标对板块训练的指导作用显示文摘通过Omega wave系统(运动员实时机能评定)的心率变异性、心电图变异及Ω电位等指标在拳击小周期训练监控中的应用,探讨拳击运动的项目特征、人群特征和对板块训练构建的指导意义。结果表明拳击运动员迷走神经功能偏低,承受极限量负荷能力弱,板块训练模式是理想选择;拳击能量代谢具有以氧代谢为支撑,无氧代谢为主,磷酸源代谢为制胜关键的混氧运动代谢特征,拳击板块训练应突出强度要素;拳击运动员疲劳较多体现在中枢功能变化,且对心肺机能影响明显,不易开展持续的大运动量训练。综合评价各指标变化特点,拳击训练应采用板块训练模式为宜。 | 杨晓强 | 2013 | 湖北体育科技2013，32，1： | 4 |
| 15 | Omega Wave系统评价赛艇运动员心功能的应用研究显示文摘运用实验法、比较法等对广东省优秀赛艇运动员一周强度训练前后机体疲劳状态进行监测,通过Omega Wave系统评价运动员的心功能。结果表明:部分运动员神经疲劳程度偏高,个别运动员已产生疲劳积累。针对改善疲劳状态提出了若干建议。 | 刘晓春 | 2013 | 湖北体育科技2013，32，8： | 3 |
| 16 | 模糊度搜索的优化算法显示文摘本文讨论了一种模糊度估算的优化方法—OMEGA(Optimal method for estimating GPS ambiguities)方法。该方法基于经典的最小二乘搜索过程,首先通过对改化后观测向量的估算,达到了收缩模糊度搜索空间,加快模糊度正确性验证之目的;然后进行矩阵分解,改进了模糊度残差二次型的计算方法,加快模糊度搜索速度。实算结果表明,该方法较一般最小二乘过程效率提高了60%。 | 柴洪洲 | 2002 | 全球定位系统2002，27，1： | 3 |
| 17 | 火星快车OMEGA高光谱探测矿物组成的新进展显示文摘主要介绍'火星快车(Mars Express)'搭载的'可见光及红外矿物制图光谱仪(OMEGA)'及其采集数据的特点、大气校正方法和矿物识别研究的新进展。'经验传输函数法'(ETF)是目前O-MEGA数据大气校正普遍采用的方法。OMEGA数据已经成功揭示了火星表面矿物和组成的多样性和复杂性。OMEGA检测到与水蚀变相关的层状硅酸盐矿物绿脱石、绿泥石和蒙脱石等主要分布于古老的诺亚期的露头上,这些层状硅酸盐矿物可能是火成岩矿物长期持续与液态水系统作用的结果。含水硫酸盐类矿物石膏、水镁矾和多水硫酸盐等水合化学沉积矿物在亮色调层状地层区的发现,表明火星表面有大量与水作用相关的蒸发盐的存在。火星表面缓慢风化形成的无水铁氧化物主要分布于北半球铁镁质含量低的低地(lowland)地区。OMEGA可以识别辉石和橄榄石,能够区分高钙辉石和低钙辉石。高钙辉石主要分布于Hesperian期的低反照率的火山岩分布地区、黑色沙丘和撞击坑喷射物分布区;低钙辉石主要分布于老的诺亚期的亮色调露头分布区。OMEGA在反照率变化大的极地冰盖地区可以识别水冰和CO2冰。水冰主要利用1.08μm、1.25μm、1.51μm和2.0μm特征吸收波段来识别。水冰各吸收特征波段的吸收强度与水冰的粒度呈正相关。CO2冰主要利用1.43μm、2.0μm和2.6μm特征吸收波段来识别。 | 祝民强 周万蓬 胡全一 | 2010 | 地球科学进展2010，25，7： | 3 |
| 18 | 管节接头OMEGA止水带安装工艺显示文摘为确保沉管接头OMEGA止水带水密质量及120 a使用寿命,根据港珠澳大桥岛隧工程技术标准及沉管接头OMEGA止水带的施工要求,制定了一套适合的工艺方案,详细叙述了OMEGA止水带的安装步骤及注意事项。对类似工程具有一定的参考价值。 | 周建民 唐永波 魏杰 | 2016 | 中国港湾建设2016，36，7： | 2 |
| 19 | 极端事件下尾部风险度量的比较分析显示文摘金融市场极端事件的接连发生使人们不得不试图对这些极端事件,即对尾部风险做出精确的判断和预测。本文采用广义Pareto方法,对风险价值(VaR),预期损失(ES)进行的估计,并引进Omega新风险指标计算其分布的尾部特性。将这些方法应用到上证指数的实证分析中进行比较研究。 | 张进滔 李竹渝 | 2006 | 统计与决策2006，22，12： | 2 |
| 20 | Extension Omega and Omega-Liutex methods applied to identify vortex structures in viscoelastic turbulent flow显示文摘The vortex structure plays a significant role in the investigation of the turbulent drag reduction effect of the viscoelastic turbulent flow.This paper aims to find out an optimal vortex identification method for the viscoelastic turbulent flows,and then studies the turbulent drag reduction mechanism by analyzing the characteristics of the identified vortex structures in the turbulent flows of the viscoelastic fluids.The Q,λ2,Liutex,Omega(Ω)and Omega-Liutex(ΩR)methods are adopted for the identification of vortex structures in the forced homogeneous isotropic turbulence(FHIT)with/without the polymer additive,respectively.The comparison among these five methods shows that the threshold values for the Q,λ2 and Liutex methods should be specially adjusted so as to suitably describe the strong and weak vortex structures in the FHIT of both the Newtonian and viscoelastic fluids,while a fixed threshold value of 0.52 for theΩandΩR methods is effective for both the Newtonian and viscoelastic fluids.The comparison between the identified vortex structures in the FHIT with and without the polymer additive indicates that theΩandΩR methods are more appropriate for the vortex identification because their dimensionless values with a fixed range from 0 to 1 can avoid the effect of the different ranges of the Q,λ2 and∣R∣(for the Liutex method)for the Newtonian and viscoelastic fluids.This also illustrates that theΩandΩR methods can be extended to identify the vortex structures in the turbulent flow of the viscoelastic fluid.Finally,the characteristics of the vortex structures in the FHIT of the viscoelastic fluid are analyzed by utilizing theΩandΩR methods.The results show that both the strong and weak vortex structures are inhibited by increasing the concentration of the polymer solution and by decreasing the Weissenberg number,especially for the weak vortex structures. | Lu Wang Zhi-ying Zheng Wei-hua Cai Wan-you Li | 2019 | Journal of Hydrodynamics2019，31，5： | 2 |
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