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CONSERVATION OF MOIST POTENTIAL VORTICITY AND DOWN-SLIDING SLANTWISE VORTICITY DEVELOPMENT

Acta meteorologica Sinica 1996年第4期10卷 399-418页

作者：吴国雄蔡雅萍唐晓菁 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics(LASG).institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100080

An accurate form of the moist potential vorticity(MPV)equation was deduced from a complete set of primitive *** was shown that motion in a saturated atmosphere without diabatic heat- ing and friction conserves moist potential *** property was then used to investigate the de- velopment of vertical vorticity in moist baroclinic *** show that in the framework of moist isentropic coordinate,vorticity development can result from reduction of convective stability,or convergence,or latent heat release at isentropic ***,the application of the usual analy- sis of moist isentropic potential vorticity is limited due to the declination of moist isentropic surfaces. and a theory of development based on z-coordinate and p-coordinate was then *** to this theory,whether the atmosphere is moist-symmetrically stable or unstable,or convective stable or unstable,the reduction of convective stability,the increase of the vertical shear of horizontal wind or moist baroclinity may result in the increase of vertical vorticity,so long as the moist isentropic surface is *** larger the declination of the moist isentropic surface,the more vigorous the develop- ment of vertical *** a region with a monsoon front to the north and the warm and moist air to the south,or by the north of the front,the moist isentropes are very *** is the region most favorable for development of vorticities and formation of torrential rain. For a case of persistent torrential rain occurring in the middle and lower reaches of the Changjiang and Huaihe Rivers in June 11-15,1991,moist potential vorticity analysis,especially the isobaric analysis of its vertical and horizontal components,***1 and MPV2,respectively,is effective for identifying synoptic systems not only in middle and high latitudes,but also in low lati- tudes and in the lower *** can serve as a powerful tool for the diagnosis and prediction of torrential rai

关键词： moist potential vorticity(MPV) slantwise vorticity development(SVD) moistsymmetrical instability

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Theoretical approach to one-dimensional detonation instability

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Applied Mathematics and Mechanics(English Edition) 2016年第9期37卷 1231-1238页

作者： Chun WANG Gaoxiang XIANG Zonglin JIANG State Key Laboratory of High Temperature Gas dynamics Chinese Academy of Sciences

Detonation instability is a fundamental problem for understanding the microbehavior of a detonation front. With the theoretical approach of shock dynamics, detonation instability can be mathematically described as a second-order ordinary difference equation. A one-dimensional detonation wave can be modelled as a type of oscillators. There are two different physical mechanisms controlling the behaviors of a detonation. If the shock Mach number is smaller than the equilibrium Mach number, the fluid will reach the sonic speed before the end of the chemical reaction. Then, thermal chock occurs, and the leading shock becomes stronger. If the shock Mach number is larger than the equilib- rium Mach number, the fluid will be subsonic at the end of the chemical reaction. Then, the downstream rarefaction waves propagate upstream, and weaken the leading shock. The above two mechanisms are the basic recovery forces toward the equilibrium state for detonation sustenance and propagation. The detonation oscillator concept is helpful for understanding the oscillating and periodic behaviors of detonation waves. The shock dynamics theory of detonation instability gives a description of the feedback regime of the chemical reaction, which causes variations of the leading shock of the detonation. Key words detonation wave, detonation instability, shock wave, chemical reaction

关键词： detonation wave detonation instability shock wave chemical reaction

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Progress in Research of Stratosphere—Troposphere Interactions:Application of Isentropic Potential Vorticity dynamics and the Effects of the Tibetan Plateau

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Journal of Meteorological Research 2014年第5期28卷 714-731页

作者：任荣彩吴国雄 CAI Ming 孙舒悦刘新李伟平 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences Department of Earth Oceanand Atmospheric ScienceFlorida State University University of Chinese Academy of Sciences Qomolangma Atmospheric and Environmental Observation and Research Station Institute of Tibetan Plateau ResearchChinese Academy of Sciences Beijing Climate Center China Meteorological Administration

This paper reviews recent progress in understanding isentropic potential vorticity （PV） dynamics during interactions between the stratosphere and troposphere, including the spatial and temporal propagation of circulation anomalies associated with the winter polar vortex oscillation and the mechanisms of stratosphere- troposphere coupling in the global mass circulation framework. The origins and mechanisms of interannual variability in the stratospheric circulation are also reviewed. Particular attention is paid to the role of the Tibetan Plateau as a PV source （via its thermal forcing） in the global and East Asian atmospheric circulation. Diagnosis of meridional isentropic PV advection over tile Tibetan Plateau and East Asia indicates that the distributions of potential temperature and PV over the east flank of the Tibetan Plateau and East Asia favor a downward and southward isentropic transport of high PV from the stratosphere to the troposphere. This transport manifests the possible influence of the Tibetan Plateau on the dynamic coupling between the stratosphere and troposphere during summer, and may provide a new framework for understanding the climatic effects of the Tibetan Plateau.

关键词： isentropic potential vorticity theory stratosphere-troposphere interactions Tibetan Plateau

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Coupling Effects of A Deep-Water Drilling Riser and the Platform and the Discharging fluid Column in An Emergency Disconnect Scenario

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China Ocean Engineering 2020年第1期34卷 21-29页

作者： MENG Shuai CHEN Yong CHE Chi-dong State Key Laboratory of Ocean Engineering Collaborative Innovation Center for Advanced Ship and Deep-sea ExplorationShanghai Jiao Tong UniversityShanghai 200240China Shanghai Marine Diesel Engine Research institute Shanghai 200240China

As drilling operations move into remote locations and extreme water depths, recoil analysis requires more careful considerations and the incidence of emergency disconnect is increased inevitably. To accurately capture the recoil dynamics of a deep-water riser in an emergency disconnect scenario, researchers typically focus on modelling the influential subsystems (e.g., the tensioner, the mud discharge and seawater refilling process) which can be solved in the preprocessing, and then the determined parameters are transmitted into an existing global riser analysis software. Distinctively, the current study devotes efforts into the coupling effects resulting from that the suspended riser reacts the platform heave motion via the tensioner system in the course of recoil and the discharging fluid column follows the oscillation of the riser in the mud discharge process. Four simulation models are established based on lumped mass method employing different formulas for the top boundary condition of the riser and the discharging flow acceleration. It demonstrates that the coupling effects discussed above can significantly affect the recoil behavior during the transition phase from initial disconnect to the final hang-off state. It is recommended to develop a fully- coupled integrated model for recoil analysis and anti-recoil control system design before extreme deep-water applications.

关键词： recoil analysis emergency disconnect coupling effect platform excitation

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非晶态与晶态锆基合金对纳秒脉冲激光烧蚀响应的对比研究

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Acta Mechanica Sinica 2022年第2期38卷 181-190,I0002页

作者：宋破吴先前戴兰宏蒋敏强 State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 101408China Key Laboratory of Mechanics in fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China

本文系统性地对比研究了非晶态与晶态锆基合金对纳秒脉冲激光的烧蚀响应,主要关注两种合金靶的多物理烧蚀过程以及靶表面烧蚀形貌.结果表明,激光诱导等离子体及其产生的冲击波动力学均符合理想爆轰波理论,并且与靶材原子拓扑结构无关.... 详细信息

本文系统性地对比研究了非晶态与晶态锆基合金对纳秒脉冲激光的烧蚀响应,主要关注两种合金靶的多物理烧蚀过程以及靶表面烧蚀形貌.结果表明,激光诱导等离子体及其产生的冲击波动力学均符合理想爆轰波理论,并且与靶材原子拓扑结构无关.两种合金靶在纳秒激光烧蚀中均承受显著的过热并最终发生爆炸沸腾.爆炸沸腾在靶表面形成一种多层级烧蚀形貌:由纳米孔洞广泛分布的微米凹坑.相比于晶态靶,非晶合金靶呈现出较浅的凹坑以及较小的纳米孔洞.这是由于非晶合金靶在激光烧蚀中具有较浅的热影响区,但过热程度较高.进一步研究发现,这种微纳多层级烧蚀形貌可有效调节两种合金靶的表面润湿性能,从初始亲水性改变为疏水性;非晶和晶态靶的表面接触角分别提高约119%和64%.本工作表明非晶合金对纳秒脉冲激光烧蚀具有更好的防护性能,并为非晶态或晶态合金的润湿性调节提供了一种可行且便捷的方法.

关键词：非晶合金锆基合金热影响区纳秒脉冲激光晶态合金激光诱导等离子体纳秒激光激光烧蚀

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Nonlinear Vibration of A Loosely Supported Curved Pipe Conveying Pulsating fluid under Principal Parametric Resonance

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Acta Mechanica Solida Sinica 2016年第5期29卷 468-478页

作者： Yangyang Luo Min Tang Qiao Ni Yikun Wang Lin Wang Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074 China Wuhan Second ship Design and Research institute Wuhan 430205 China

In this paper,the nonlinear dynamics of a curved pipe is investigated in the case of principal parametric resonance due to pulsating flow and impact with loose *** coupled in-plane and out-of-plane governing equations with the consideration of von Karman geometric nonUnearity are presented and discretized via the differential quadrature method（DQM）.The nonlinear dynamic responses are calculated numerically to demonstrate the influence of pulsating ***,the impact is taken into *** influence of clearance on frettingwear damage,such as normal work rate,contact ratio and impact force level,is demonstrated.

关键词： curved governing quadrature clearance Karman numerically loose conveying parametric dynamical

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Understanding the dynamical mechanism of year-to-year incremental prediction by nonlinear time series prediction theory

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Atmospheric and Oceanic Science Letters 2018年第1期11卷 71-77页

作者： Bi Shu-Ting Wang Peng-Fei Pan Xin-Nong Li Chao-Fan Center for Monsoon System Research(CMSR) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Key Laboratory for Atmosphere and Global Environment Observation(LAGEO) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina

基于年际增量预测(YIP)方法的数学原理,推导得出新的非线性时间序列预测(NP)方法,并从理论上证明了两种预测方法在一定条件下的等效性。以长江中下游地区的夏季降水为例,新的NP方法在使用年际增量作为强迫项时,可以取得与YIP相当的预测... 详细信息

基于年际增量预测(YIP)方法的数学原理,推导得出新的非线性时间序列预测(NP)方法,并从理论上证明了两种预测方法在一定条件下的等效性。以长江中下游地区的夏季降水为例,新的NP方法在使用年际增量作为强迫项时,可以取得与YIP相当的预测效果。而且,通过调整重构维数等参数,能够将预测模型重构于高于一维的相空间中,进而可获得更好的预测效果。研究发现YIP方法除了有物理基础外,还有隐含的动力基础,新NP模型有助于提高短期气候预测的水平。

关键词：年际增量非线性时间序列降水季节预测

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Prediction of superionic state in LiH_(2) at conditions enroute to nuclear fusion

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Chinese Physics B 2023年第10期32卷 566-571页

作者：李福德王豪李津龙耿华运 National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid PhysicsCAEPMianyang 621900China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

Hydrogen and lithium,along with their compounds,are crucial materials for nuclear fusion ***-pressure studies have revealed intricate structural transitions in all these ***,research on lithium hydrides beyond LiH has mostly focused on the low-temperature ***,we use density functional theory and ab initio molecular dynamics simulations to investigate the behavior of LiH_(2),a hydrogen-rich compound,near its melting *** study is particularly relevant to the low-pressure region of the compression pathway of lithium hydrides toward *** discovered a premelting superionic phase transition in LiH_(2)that has significant implications for its mass transportation,elastic properties,and sound *** theoretical boundary for the superionic transition and melting temperature was then *** contrast,we also found that the primary compound of lithium hydrides,LiH,does not exhibit a superionic *** findings have important implications for optimizing the compression path to achieve the ignition condition in inertial confinement fusion research,especially when lithium tritium-deuteride(LiTD)is used as the fuel.

关键词： lithium polyhydrides high pressure and high temperature superionic state phase transition

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Variational Quality Control of Non-Gaussian Innovations in the GRAPES m3DVAR System: Mass Field Evaluation of Assimilation Experiments

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Advances in Atmospheric Sciences 2021年第9期38卷 1510-1524页

作者： Jie HE Xulin MA Xuyang GE Juanjuan LIU Wei CHENG Man-Yau CHAN Ziniu XIAO Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory of Meteorological DisasterNanjing University of Information Science and TechnologyNanjing 210044China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Beijing institute of Applied Meteorology Beijing 100029China Department of Meteorology and Atmospheric Science and Center for Advanced Data Assimilation and Predictability TechniquesThe Pennsylvania State UniversityUniversity ParkPA 16801USA

The existence of outliers can seriously influence the analysis of variational data *** control allows us to effectively eliminate or absorb these outliers to produce better analysis *** particular,variational quality control(VarQC) can process gray zone outliers and is thus broadly used in variational data assimilation *** this study,governing equations are derived for two VarQC algorithms that utilize different contaminated Gaussian distributions(CGDs): Gaussian plus flat distribution and Huber norm *** such,these VarQC algorithms can handle outliers that have non-Gaussian ***,these VarQC algorithms are implemented in the Global/Regional Assimilation and PrEdiction System(GRAPES) model-level three-dimensional variational data assimilation(m3 DVAR) *** using artificial observations indicate that the VarQC method using the Huber distribution has stronger robustness for including outliers to improve posterior analysis than the VarQC method using the Gaussian plus flat ***,real observation experiments show that the distribution of observation analysis weights conform well with theory,indicating that the application of VarQC is effective in the GRAPES m3 DVAR *** case study and longperiod data assimilation experiments show that the spatial distribution and amplitude of the observation analysis weights are related to the analysis increments of the mass field(geopotential height and temperature).Compared to the control experiment,VarQC experiments have noticeably better posterior mass ***,the VarQC method using the Huber distribution is superior to the VarQC method using the Gaussian plus flat distribution,especially at the middle and lower levels.

关键词： variational quality control non-Gaussian distribution innovation outlier data assimilation

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Review of Molecular Simulation Method for Gas Adsorption/desorption and Diffusion in Shale Matrix

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Journal of Thermal Science 2019年第1期28卷 1-16页

作者： WANG Hui QU Zhiguo YIN Ying BAI Junqiang YU Bo School of Aeronautics Northwestern Polytechnical University MOE Key Laboratory of Thermo-fluid Science and Engineering School of Energy and Power Engineering Xi'an Jiaotong University Mechanical Engineering College Beijing Institute of Petrochemical Technology

Shale gas is becoming an increasingly promising alternative energy resource because of its high efficiency and environment-friendly characteristic. The amount of adsorbed gas on the shale matrix surfaces and dissolved gas in the shale matrix bulk is the dominant factor in the long-term productivity of shale reservoir. Although experimental measurements have been extensively carried out to investigate the gas adsorption and diffusion properties in the shale matrix, they cannot provide the detailed information on the microscopic transport mechanism of shale gas during the gas production process. Molecular simulation can accurately visualize the gas adsorption/desorption and diffusion processes in the shale matrix. In the present study, the recent research advances of molecular simulation on gas adsorption/desorption and diffusion in the shale matrix are reviewed. Firstly, the density functional theory(DFT) for shale gas molecule desorption/adsorption on the surface of the matrix crystal is illustrated. Then, the grand canonical Monte Carlo(GCMC) method predicting the amount of shale gas desorption/adsorption in the shale matrix crystal is introduced. Finally, molecular dynamics simulation(MD) for gas diffusion in the shale matrix is elucidated. Further developments of the molecular simulation method in shale gas production are also discussed.

关键词： shale gas molecular simulation adsorption/desorption diffusion

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