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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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Optimization of Center of Gravity Position and Anti-Wave Plate Angle of Amphibious Unmanned Vehicle Based on Orthogonal Experimental Method

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2027-2041页

作者： Deyong Shang Xi Zhang Fengqi Liang Chunde Zhai Hang Yang Yanqi Niu School of Mechanical Electronic&Information EngineeringChina University of Mining and Technology(Beijing)Beijing100083China institute of Intelligent Mining&Robotics China University of Mining and Technology(Beijing)Beijing100083China

When the amphibious vehicle navigates in water,the angle of the anti-wave plate and the position of the center of gravity greatly influence the navigation *** the relevant research on reducing the navigation resistance of amphibious vehicles by adjusting the angle of the anti-wave plate,there is a lack of scientific selection of parameters and reasonable research of simulation results by using mathematical methods,and the influence of the center of gravity position on navigation characteristics is not considered at the same *** study the influence of the combinations of the angle of the anti-wave plate and the position of the center of gravity on the resistance reduction characteristics,a numerical calculation model of the amphibious unmanned vehicle was established by using the theory of computational fluid dynamics,and the experimental data verified the correctness of the numerical *** on this numerical model,the navigation characteristics of the amphibious unmanned vehicle were studied when the center of gravity was located at different positions,and the orthogonal experimental design method was used to optimize the parameters of the angle of the anti-wave plate and the position of the center of *** results show that through the parameter optimization analysis based on the orthogonal experimental method,the combination of the optimal angle of the anti-wave plate and the position of the center of gravity is *** the numerical simulation result of resistance is consistent with the predicted optimal *** with the maximum navigational resistance,the parameter optimization reduces the navigational resistance of the amphibious unmanned vehicle by 24%.

关键词： Amphibious unmanned vehicle orthogonal experimental design anti-wave plate center of gravity resistance characteristic

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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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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

Previous studies have shown that year-to-year incremental prediction （YIP） can obtain considerable skill in seasonal forecasts. This study analyzes the mathematical deRnition of YiP and derives its formula in the nonlinear time series prediction （NP） method, it is shown that the two methods are equivalent when the prediction time series is embedded in one-dimensional phase space. Compared to previous NP models, the new one introduces multiple external forcings in the form of year-to-year increments. The year-to-year increments have physical meaning, which is better than the NP model with empirically chosen parameters. The summer rainfall over the middle to lower reaches of the Yangtze River is analyzed to examine the prediction skill of the NP models. Results show that the NP model with year-to-year increments can reach a similar skill as the YiP model. When the embedded number of dimensions is increased to two, more accurate prediction can be obtained. Besides similar results, the NP method has more dynamical meaning, as it is based on the classical reconstruction theory. Moreover, by choosing different embedded dimensions, the NP model can reconstruct the dynamical curve into phase space with more than one dimension, which is an advantage of the NP model. The present study suggests that YIP has a robust dynamical foundation, besides its physical mechanism, and the modified NP model has the potential to increase the operationaJ skill in short- term climate prediction.

关键词： Year-to-year incrementalprediction nonlineartime series prediction precipitation Yangtze River seasonal prediction

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A STUDY ON THE MECHANISM OF HIGH-LIFT GENERATION BY AN AIRFOIL IN UNSTEADY MOTION AT LOW REYNOLDS NUMBER

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Acta Mechanica Sinica 2001年第2期17卷 97-114页

作者：孙茂 institute of fluid Mechanics Beijing University of Aeronautics & AstronauticsBeijing 100083China

The aerodynamic force and flow structure of NACA 0012 airfoil performing an unsteady motion at low Reynolds number (Re = 100) are calculated by solving Navier-Stokes equations. The motion consists of three parts: the first translation, rotation and the second translation in the direction opposite to the first. The rotation and the second translation in this motion are expected to represent the rotation and translation of the wing-section of a hovering insect. The flow structure is used in combination with the theory of vorticity dynamics to explain the generation of unsteady aerodynamic force in the motion. During the rotation, due to the creation of strong vortices in short time, large aerodynamic force is produced and the force is almost normal to the airfoil chord. During the second translation, large lift coefficient can be maintained for certain time period and (C) over bar (L), the lift coefficient averaged over four chord lengths of travel, is larger than 2 (the corresponding steady-state lift coefficient is only 0.9). The large lift coefficient is due to two effects. The first is the delayed shedding of the stall vortex. The second is that the vortices created during the airfoil rotation and in the near wake left by previous translation form a short 'vortex street' in front of the airfoil and the 'vortex street' induces a 'wind'; against this 'wind' the airfoil translates, increasing its relative speed. The above results provide insights to the understanding of the mechanism of high-lift generation by a hovering insect.

关键词： high-lift airfoil flapping motion low Reynolds number

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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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A Quantitative Method of Detecting Transient Rossby Wave Phase Speed:No Evidence of Slowing Down with Global Warming

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Advances in Atmospheric Sciences 2023年第2期40卷 251-261页

作者： Yashu WU Jianhua LU School of Atmospheric Sciences Sun Yat-Sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityGuangzhou 510275China

Based on the Complex Empirical Orthogonal Functions(CEOFs)of bandpass-filtered daily streamfunction fields,a quantitative method of detecting transient(synoptic)Rossby wave phase speed(RWPhS)is *** transient RWPhS can be objectively calculated by the distance between a high(or low)center in the real part of a CEOF mode and its counterpart in the imaginary part of the same CEOF mode divided by the time span between two adjacent peaks(or bottoms)of two principal component curves for the real and imaginary parts of that CEOF *** new detection method may partly reveal the spatiotemporal heterogeneity of Rossby wave *** the mean westerly jet at 200 hPa doubles the speed of its counterpart at 500 hPa,the estimated RWPhS at both levels are around 1000 km d^(–1)and quantitatively consistent with the quasigeostrophic-theory-based RWPhS,confirming that the meridional potential vorticity gradient induced by the barotropic and baroclinic shears of mean flow,together with theβeffect,play an essential role in Rossby wave *** observations over the past four decades and a 150-year historical simulation suggest no evidence for slowing wintertime transient Rossby waves in the Northern Hemisphere,but possible regional changes are not *** emphasize that not only the mean flow speed,but also the barotropic and baroclinic shears of the mean flow,and their associated contributions to the meridional potential vorticity(PV)gradient,should be considered in investigating the possible change of Rossby waves with global warming.

关键词： Rossby waves phase speed quasigeostrophic potential vorticity

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A semi-analytical model for the propagation of Rossby waves in slowly varying flow

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Chinese Science Bulletin 2011年第25期56卷 2727-2731页

作者： LIU Fei CHAO JiPing HUANG Gang FENG LiCheng Key Laboratory of Regional Climate-Environment Research for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China International Pacific Research Center University of Hawaii at Manoa Honolulu 96822 USA National Marine Environmental Forecasting Center Beijing 100081 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100083 China

Instead of using complicated general circulation models (GCMs), a simple semi-analytical model based on ray theory has been used to study energy evolution and ray path of Rossby waves in slowly varying mean flows. Our model yields similar results to those calculated from barotropic models, and also provides a chance to study Rossby waves in the slowly varying flows with both vertical and meridional shears. The model results show that upward Rossby waves can only grow in westerlies, and decay when further ascend. The baroclinic Rossky waves are restrained by the β effect in lower latitude. In the westerly jet with meridional and vertical shears, the barotropic Rossby waves originated from south of the westerly jet, and these can grow while propagating upper-northward. The baroclinic Rossby waves originated from north of the westerly jet and can grow while propagating upward and southward. Such a semi-analytical model provides a simple forecasting tool to allow study of the local weather anomalies to the heating/topography forcing associated with the global warming.

关键词： Rossby波半解析模型传播模式大气环流模型变流西风急流 GCMS 射线路径

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