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POD analysis on vortical structures in MVG wake by Liutex core line identification

Journal of Hydrodynamics 2020年第3期32卷 497-509页

作者： xiang-rui dong Xiao-shu Cai Yinlin dong Chaoqun Liu School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering Shanghai 200093China Department of Mathematics University of Central ArkansasConway 72035USA Department of Mathematics University of Texas at ArlingtonArlington 76019USA

The Liutex core line method, first combined with the snapshot proper orthogonal decomposition (POD), is utilized in a supersonic micro-vortex generator (MVG) wake flow at Ma = 2.5 and Reθ = 5 760 to reveal the physical significance of each POD mode of the flow field. Compared with other scalar-based vortex identification methods, the Liutex core line identification is verified to be the most appropriate approach that is threshold-free and provides full information of a fluid rotation motion. Meanwhile, the Liutex integration is employed to quantitatively track the evolution of the vortices in MVG wake and is applied to the determination of the effective control section of the MVG wake for the optimization study of MVG design. The physical mechanism of each POD mode for multi-scale and multi-frequency vortical structures is investigated by using Liutex core line identification to give some revelations. For the mean mode (mode 0) indicating the time-averaged velocity flowfield of the MVG wake flow, a pair of primary counter-rotating streamwise vortices and another pair of secondary vortices is uniquely identified by two pairs of Liutex core lines with Liutex magnitude. In contrast, mode 1 is featured by a fluctuated roll-up motion of streamwise vortex, and the streamwise component of the MVG wake is demonstrated to be dominant in terms of the total kinetic energy contribution. Meanwhile, a dominant shedding frequency of St = 0.072 is detected from the temporal behavior of mode 2, which has the organized arc-shaped vortex structures shedding from MVG induced by the K-H instability. Additionally, mode 4 subjects to low-frequency oscillations of the wall vortices and thus takes a relatively lower frequency of St = 0.044.

关键词： Proper orthogonal decomposition(POD) vortex identification Liutex vortex core lines micro-vortex generator(MVG)

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Liutex identification on hairpin vortex structures in a channel based on msfle and moving-PIV

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Journal of Hydrodynamics 2021年第6期33卷 1119-1128页

作者： Xin-ran Tang xiang-rui dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China

The spatiotemporal evolution of hairpin vortex structures in a fully developed turbulent boundary layer is investigated qualitatively and quantitatively by using two image *** this paper,the moving single-frame and long-exposure(MSFLE)image method is used to intuitively track the evolution process of a hairpin vortex,while the moving particle image velocimetry(moving-PIV)method is applied for obtaining a moving velocity field for quantitative *** to the structural characteristics of the hairpin vortex,an inclined light sheet with an appropriate inclination of 53°is arranged to capture the complete hairpin vortex structure at Re_(θ)=97–*** addition,the core size and the rotational strength of a hairpin vortex are further defined and quantified by the Liutex vector *** evolution process of a complete hairpin vortex structure observed by MSFLE shows that the shear along the normal direction leads to an increasing strength of the hairpin vortex,accompanied by a lifting vortex head and a distance decrease between two vortex legs during the dissipation *** combining moving-PIV with the Liutex identification,the spatiotemporal evolution of four typical regions of a hairpin vortex projecting into a 53°cross-section is *** results show that the process from the generation to the dissipation of a single hairpin vortex can be well characterized and recorded by the Liutex based on the core size and rotational intensity,and the evolution process is consistent with the MSFLE *** to the statistics of vortex core size and rotation intensity along time,the evolution of the hairpin vortex necks and legs can be described as a process of enhancement followed by *** the vortex head,its evolution maintains longer attributed to its far-from-wall position,which consists of an absolute enhancement process(stage 1)with an increasing rotation strength and a constant core size,and an absolute dissipation(stage 2)with a dec

关键词： Turbulent boundary layer hairpin vortex moving single-frame and long-exposure moving particle image velocimetry(PIV) Liutex vortex identification method

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Experimental study on dynamic mechanism of vortex evolution in a turbulent boundary layer of low Reynolds number

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Journal of Hydrodynamics 2020年第5期32卷 807-819页

作者： Yan-ang Guo xiang-rui dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering Shanghai 200093China

The dynamic mechanism of the vortex generation and evolution process in a fully developed turbulent boundary layer with Reθ=97-194 is experimentally *** this study,a moving single-frame and long-exposure(MSFLE)imaging method and a moving particle image velocimetry/particle tracing velocimetry(M-PIV/PTV)are designed and implemented for measuring the temporal and spatial evolution of vortex cores in both qualitative and quantitative ways,*** the other hand,the Liutex vector,which is a new mathematical definition and identification of the vortex core proposed by Liu’s group,is first applied in the experiment for the structural visualization and quantitative analysis of the local fluid *** results show that an intuitional process of vortex evolution can be clearly observed by tracking the vortex using MSFLE and verify that the roll-up of the shear layer induced by shear instability is the origin of vortex formation in ***,a quantitative investigation in terms of the critical vortex core boundary(size)and its accurate rotation strength is carried out based on the Liutex vector field analysis by M-PIV/*** to statistics of the relation between vortex core size and the rotation strength during the whole process,the physical mechanism of vortex generation and evolution in a turbulent boundary layer of low Reynolds number can be summarized as a four-dominant-state course consisting of the“synchronous linear segment(SL)-absolute enhancement segment(AE)-absolute diffusion segment(AD)-skewing dissipation segment(SD)”.

关键词： Turbulent boundary layer high-and low-speed fluid vortex generation moving single-frame and long-exposure moving particle image velocimetry/particle tracing velocimetry Liutex vector

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Liutex theoretical system and six core elements of vortex identification

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Journal of Hydrodynamics 2020年第2期32卷 197-211页

作者： Yi-qian Wang Yi-sheng Gao Hongyi Xu xiang-rui dong Jian-ming Liu Wen-qian Xu Meng-long Chen Chaoqun Liu School of Mathematical Science Soochow UniversitySuzhou215006China College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016China Aeronautics and Astronautics Department Fudan UniversityShanghai200433China School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China School of Mathematics and Statistics Jiangsu Normal UniversityXuzhou221116China Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou310018China SimpleHPC LTD. Shanghai200030China Department of Mathematics University of Texas at ArlingtonArlington76019USA

The third-generation vortex identification method of Liutex(previously called Rortex)was introduced by the team led by *** Liu from University of Texas at Arlington to mathematically extract the rigid rotation part from the fluid motion,and thus to define and visualize *** the vorticity-based first generation and the scalar-valued second generation,Q,λ2,Δandλci methods for example,the Liutex vector provides a unique,mathematical and systematic way to define vortices and visualize vortical structures from multiple perspectives without *** this article,we summarize the recent developments of the Liutex framework and discuss the Liutex theoretical system including its existence,uniqueness,stability,Galilean invariance,locality and globality,decomposition in tensor and vector forms,Liutex similarity in turbulence,and multiple Liutex-based vortex visualization methods including Liutex lines,Liutex magnitude iso-surfaces,Liutex-Ωmethod,and Liutex core line method,etc..Thereafter,the six core elements of vortex identification,including(1)absolute strength,(2)relative strength,(3)local rotational axis,(4)vortex rotation axes,(5)vortex core size,(6)vortex boundary,are used as touchstones against which the Liutex vortex identification system is *** is demonstrated with illustrative examples that the Liutex system is able to give complete and precise information of all six core elements in contrast to the failure and inaccuracy of the first and second-generation *** important concept that vorticity cannot represent vortex and the superiority of the Liutex system over previous methods are reiterated and stated in appropriate places throughout the ***,the article concludes with future perspectives,especially the application of the Liutex system in studying turbulence mechanisms encouraged by the discovery of Liutex similarity *** a newly defined physical quantity,Liutex may open a door for quantified vortex and turbulenc

关键词： Vortex identification Liutex vector six core elements Liutex core line Liutex similarity turbulence

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Third generation of vortex identification methods:Omega and Liutex/Rortex based systems

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Journal of Hydrodynamics 2019年第2期31卷 205-223页

作者： Chaoqun Liu Yi-sheng Gao xiang-rui dong Yi-qian Wang Jian-ming Liu Yu-ning Zhang Xiao-shu Cai Nan Gui Department of Mathematics University of Texas at ArlingtonArlington 76019TexasUSA College of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China School of Mathematics and Statistics Jiangsu Normal UniversityXuzhou 221116China Key Laboratory of Condition Monitoring and Control for Power Plant Equipment(Ministry of Education) School of EnergyPower and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

A vortex is intuitively recognized as the rotational/swirling motion of fluids,but a rigorous and universally-accepted definition is still not *** 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 *** 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 *** 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 *** 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 *** 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 *** 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 ***/Rortex is a new physical quantity with scalar,vector and tensor forms exactly representing the local rigid rotation of ***,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 *** in early 2019,a Liutex/Rortex based Omega method called Omega-Liutex,which combines the respective advantages o

关键词： Vortex definition vortex identification Omega Liutex/Rortex direct numerical simulation turbulence

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A selected review of vortex identification methods with applications

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Journal of Hydrodynamics 2018年第5期30卷 767-779页

作者： Yu-ning Zhang Xu Qiu Fei-peng Chen Kai-hua Liu Yu-ning Zhang xiang-rui dong Chaoqun Liu Key Laboratory of Condition Monitoring and Control for Power Plant Equipment (Ministry of Education) School of Energy Power and Mechanical Engineering North China Electric Power University Beijing 102206 China Beijing South-to-North Water Diversion Tuancheng Lake Management Office Beijing 100195 China College of Mechanical and Transportation Engineering China University of Petroleum-Beijing Beijing 102249 China Beijing Key Laboratory of Process Fluid Filtration and Separation China University of Petroleum-Beijing Beijing 102249 China National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing 210094 China Department of Mathematics University of Texas at Arlington Arlington Texas USA

In the present review, recent progress on the vortex identification methods are introduced with a focus on the newly proposed omega method（ Ω method）. The advantages of Ω method are summarized with many illustrating examples. Furthermore, comparing with other existing methods（e.g., Q criterion and λ2 criterion）, one of the characteristics of Ω method is its independence on the chosen threshold values for vortex identifications. The important parameters involved for the practical applications of Ω method are further discussed in detail together with the physical interpretation of the Ω and some suggestions of the future work. Other emerging topics（e.g., Lagrangian coherent structure and Rortex） are also introduced with comments.

关键词： Vortex identification turbulence generation Ω method vorticity concentration Galilean invariant Rortex

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Insight into the particle shape on the impact of dry granular flow against a rigid barrier: A DEM study

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Journal of Earth Science 2025年

作者： rui-Xiao Zhan dong Su xiang-Sheng Chen Yuan-Jun Jiang Guo-Ping Lei Jing-Jing Yu Key Laboratory for Resilient Infrastructures of Coastal Cities (MOE)， Shenzhen University College of Civil and Transportation Engineering， Shenzhen University School of Architecture and Urban Planning， Shenzhen University Shenzhen Key Laboratory of Green， Efficient and Intelligent Construction of Underground Metro Station， Shenzhen University Institute of Mountain Hazards and Environment， Chinese Academy of Sciences School of Transportation， Civil Engineering & Architecture， Foshan University

The effect of particle shape on the impact of dry granular flow remains an open area for further investigation. Five distinct particle shapes were examined in this study using discrete element simulations after calibrating the numerical model using a published work. The findings indicated that the particle shape had a significant influence on granular mobility. With negligible variations in normalized kinetic energy between particles of different shapes， the effect of particle shape on the increasing rate of kinetic energy became more obvious. All irregular particle scenarios had longer accumulated particle lengths down the channel than spherical particles. Variations in particle shape led to adjustments in the distribution of impact forces on the barrier. These findings substantially enhance our understanding of the distinctive effects of particle shapes on the impact mechanism of dry granular flow.

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AZD1775 synergizes with SLC7A11 inhibition to promote ferroptosis

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Science China Life Sciences 2025年第1期68卷 204-218页

作者： Chen Xiong Hong Ling Yingdan Huang Hanzhi dong Bangxiang Xie Qian Hao xiang Zhou Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences Fudan University Department of Oncology Shanghai Medical CollegeFudan University Department of Breast Surgery Fudan University Shanghai Cancer CenterFudan University Department of Oncology First Affiliated Hospital of Nanchang University Beijing Institute of Hepatology Beijing Youan HospitalCapital Medical University Beijing Engineering Research Center for Precision Medicine and Transformation of Hepatitis and Liver Cancer Key Laboratory of Breast Cancer in Shanghai Fudan University Shanghai Cancer CenterFudan University Shanghai Key Laboratory of Medical Epigenetics International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology)Institutes of Biomedical SciencesFudan University

Tumor suppressor p53-mediated cell cycle arrest and DNA damage repair may exert cytoprotective effects against cancer therapies, including WEE1 inhibition. Considering that p53 activation can also lead to multiple types of cell death, the role of this tumor suppressor in WEE1 inhibitor-based therapies remains disputed. In this study, we reported that nucleolar stress-mediated p53 activation enhanced the WEE1 inhibitor AZD1775-induced ferroptosis to suppress lung cancer growth. Our findings showed that AZD1775 promoted ferroptosis by blocking cystine uptake, an action similar to that of Erastin. Meanwhile, inhibition of WEE1 by the WEE1 inhibitors or si RNAs induced compensatory upregulation of SLC7A11, which conferred resistance to ferroptosis. Mechanistically, AZD1775 prevented the enrichment of H3K9me3, a histone marker of transcriptional repression, on the SLC7A11 promoter by repressing the expression of the histone methyltransferase SETDB1, thereby enhancing NRF2-mediated SLC7A11 transcription. This finding was also validated using the H3K9me3 inhibitor BRD4770. Remarkably, we found that the nucleolar stress-inducing agent Actinomycin D(Act. D) inhibited SLC7A11 expression by activating p53, thus augmenting AZD1775-induced ferroptosis. Moreover, the combination of AZD1775 and Act. D synergistically suppressed wild-type p53-harboring lung cancer cell growth both in vitro and in vivo. Altogether, our study demonstrates that AZD1775 promotes ferroptosis by targeting cystine uptake but also mediates the adaptive activation of SLC7A11 through the WEE1-SETDB1 cascade and NRF2-induced transcription, and inhibition of SLC7A11 by Act. D boosts the anti-tumor efficacy of AZD1775 by enhancing ferroptosis in cancers with wild-type p53.

关键词： p53 NRF2 SLC7A11 WEE1 AZD1775 ferroptosis nucleolar stress

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Decentralized fault diagnosis of discrete-event systems with unreliable sensors using linear temporal logic

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Science China(Information Sciences) 2025年第1期68卷 322-341页

作者： Weijie dong Shaoyuan LI xiang YIN Key Laboratory of System Control and Information Processing Ministry of EducationDepartment of Automation Shanghai Jiao Tong University

In this paper,we investigate a decentralized diagnosis problem of a discrete-evnt system(DES) subject to unreliable sensors,where the sensor observations of local diagnosers may be non-deterministic as a result of possible *** studies on decentralized robust diagnosis can only deal with different types of sensor failures separately,e.g.,all sensors suffer from the same type of sensor failures such as intermittent sensor failures or permanent sensor ***,since sensors of different local diagnosers may face different external environments and have different internal characteristics,sensors corresponding to different local diagnosers may also have their own fault *** this paper,we propose a flexible framework of decentralized diagnosis for DES subject to unreliable sensors such that sensors of different local diagnosers are permitted to have different types of sensor *** this end,we extend the existing decentralized diagnosis framework to the case where there exist common sensors broadcasting their observations to all local *** apply linear temporal logic(LTL) to constrain infinite behaviors of private sensors of local diagnosers and common ***,a new notion of φ-codiagnosability is proposed as the necessary and sufficient condition for the existence of a decentralized diagnoser that works correctly under sensors,satisfying LTL-based sensor ***,we provide an effective approach to verify the φ-codiagnosability.

关键词： discrete event systems decentralized diagnosis codiagnosability automata

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基于主题动态模型的法律因果关系研究

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政法论丛 2017年第1期 155-161页

作者：张瑞祥王东波江苏省司法厅研究室江苏南京210024 南京农业大学信息科学技术学院江苏南京210095

主题动态模型为探究学科研究趋势和主题演化形式提供了新的思路,使用该模型对法律因果关系进行分析可有效验证模型的有效性并为推广模型提供经验,并且针对学科研究内容的分析也为学科整体发展提供了有益的支持。通过对2009-2013年的549... 详细信息

主题动态模型为探究学科研究趋势和主题演化形式提供了新的思路,使用该模型对法律因果关系进行分析可有效验证模型的有效性并为推广模型提供经验,并且针对学科研究内容的分析也为学科整体发展提供了有益的支持。通过对2009-2013年的5494篇因果关系相关文献的主题动态分析,所取得的结果验证了主题动态模型在应用于因果关系学科上的有效性,同时基于主题动态模型的分析结论,对学科研究历史的变迁进行了总结和评述。由于主题动态模型是一种新提出的研究方法,并且缺乏在人文社会科学上的应用,从而导致本研究缺乏对其他学科进行横向性能的比较。

关键词：主题动态模型因果关系流行性连续性

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