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Dynamical analysis of mesoscale eddy-induced ocean internal waves using linear theories

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Acta Oceanologica Sinica 2008年第3期27卷 60-69页

作者： XU Qing ZHENG Quanan LIN Hui LIU Yuguang SONG Y Tony YUAN Yeli Institute of Space and Earth Information Science The Chinese University of Hong Kong Hong Kong China department of Atmospheric and Oceanic Science University of Maryland College Park Maryland USA Physical Oceanography Laboratory Ocean University of China Qingdao 266100 China jet propulsion Laboratory California Institute of Technology Pasadena California USA Key Laboratory for Marine Science and Numerical Modeling of State Oceanic Administration First Institute of Oceanography State Oceanic Administration Qingdao 266061 China

This study aims to explore generation mechanisms of the ocean internal wave using the dynamical analysis methods based on linear theories. Historical cruise measurements and recent synthetic aperture radar （SAR） observations of mesoscale eddies with diameter of several tens of kilometers to hundreds of kilometers show that the internal wave packets with wavelength of hundreds of meters to kilometer exist inside the mesoscale eddies. This coexistence phenomenon and inherent links between the two different scale processes are revealed in the solutions of governing equations and boundary conditions for the internal wave disturbance with a horizontally slowly variable amplitude in a cylindrical coordinate system. The theoretical solutions indicate that the instability of eddy current field provides the dynamical mechanism to internal wave generation. The derived dispersion relation indicates that the internal wave propagation is modified by the eddy current field structure. The energy equation of the internal waves clearly shows the internal wave energy increment comes from the eddy. The theoretical models are used to explain the observation of the mesoscale eddy-induced internal waves off the Norwegian coast. The two-dimensional waveform solution of the anticyclonic eddy-induced internal wave packet appears as ring-shaped curves, which contains the typical features of eddy stream lines. The comparison of theoretical solutions to the structure of the internal wave packets on SAR image shows a good agreement on the major features.

关键词： ocean internal waves mesoscale eddy current field instability SAR image

Quantitative Separation of the Directly-driven and Unloading Components:View from the Ionospheric Electric Field

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Quantitative Separation of the Directly-driven and Unloading...

第十二届全国日地空间物理学术讨论会

作者： W.Sun~1 X.-Y.Zhou~2 A.Du~3 1 Geophysical Institute,University of Alaska Fairbanks,Fairbanks,Alaska 2 jet propulsion Laboratory,California Institute of Technology,Pasadena,California 3 Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,China

＜正＞The natural orthogonal components （NOC） algorithm is applied to separate directly driven and unloading components in ionospheric electric field during substorms and magnetic *** well known, observations have s...

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Numerical Simulation of Shaped Charge jet Using Multi-Phase SPH Method

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Transactions of Tianjin University 2008年第B10期14卷 495-499页

作者：强洪夫王坤鹏高巍然 Faculty of Mechanical and propulsion Engineering Xi'an Hi-Tech Institute

Since the jets and detonation gaseous products are separated by sharp interfaces, the traditional smoothed particle hydrodynamics (SPH) method is difficult to avoid the computational instability at interfaces. The multi-phase SPH (MSPH) method was applied to improving the stabil-ity, which smoothes the particle density and makes pressure continuous at interfaces. Numericalexamples of jet forming process were used to test capability of the MSPH method. The results show that the method remains algorithm stability for large density gradient between the jets and gaseous products and has potential application to both the explosion and the jet problems. The effect of initiation ways of the shaped charge was discussed as well.

关键词： smoothed particle hydrodynamics (SPH) multi-phase large deformation shaped charge jet initiation

Wavenumber-4 patterns of the total electron content over the low latitude ionosphere

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Wavenumber-4 patterns of the total electron content over the...

中国科学院地质与地球物理研究所2008学术年会

作者： W.Wan,L.Liu,X.Pi,M.-L.Zhang,B.Ning,J.Xiong,and F.Ding 1 Institute of Geology and Geophysics,Chinese Academy of Sciences, Beijing,China. 2 jet propulsion Laboratory,California Institute of Technology, Pasadena,California,USA.

[1]The global ionospheric maps(GIMs) produced by JPL are used to investigate the longitudinal structure of the low latitude *** a proxy of the ionization parameter at low latitudes,the latitudinally integrated total electron content(ITEC) is first extracted from low latitude GIMs and then Fourier filtered to obtain the wavenumber-4 *** then study in detail the diurnal,seasonal and solar cycle variations of the wave *** is found that the wavenumber-4 patterns are intense and well developed in boreal summer and early boreal autumn,but quite weak in boreal *** seasonal variation is consistent with that of the zonal wind of the non-migrating tide mode *** also found that the wavenumber-4 patterns shift eastward with a shifting speed that is smaller in daytime than at *** is attributed to the contribution of both the eastward propagation of DE3 in E-region and the zonal E×B ion drifts in *** results support the suggestion that the longitudinal wavenumber-4 structure of the low latitude ionosphere should be originated from the non-migrating tide mode DE3.

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Reliability of CD-ROM Frame on the Basis of Finite Element Analysis

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Reliability of CD-ROM Frame on the Basis of Finite Element A...

2010 Chinese Control and Decision Conference

作者： Xiaoying Li~1,Liyan Han~2,Yanbin Han~3 1.Computer and Automatic Control College,Hebei Polytechnic University,Tangshan,063009,China 2.Tianjin University In-time Technology CO.,LTD,Tianjin,300072,China 3.School of jet propulsion,Beijing University of Aeronautics & Astronautics,Beijing,100083,China

＜正＞By using finite element analysis method,on the basic of finite element static analysis,taking the maximum displacement in CD-ROM as random output variable,and CD-ROM sizes and material properties as random input variables,mathematical models of a CD-ROM Reliability Analysis is *** reliability and sensitivity of maximum displacement in the model was calculated and studied.

关键词： Finite element Displacement analysis Reliability and Standard CD-ROM

The calculations of reliability model for crank-rocker mechanism

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The calculations of reliability model for crank-rocker mecha...

2010 Chinese Control and Decision Conference

＜正＞The four-bar crank-rocker mechanism is a key component of transmission,the probability analysis of crank-rocker mechanism need very high *** original error of input motion parameter,the analytical method is applied to establish the relative equation of the input errors in the crank-rocker mechanism and the output errors of *** that the input parameter errors obey standard normal distribution,reliability model of the output component errors is *** MATLAB calculated programming examples of the kinds of model *** model method is rigorous,reliability analysis is worth promoting.

关键词： Four bar crank-rocker mechanism Probabilistic analysis and Reliability model

Study of Ship propulsion Equipment Driven by High Pressure Gases

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武汉理工大学学报（交通科学与工程版） 1999年第S1期24卷 85-89页

作者： Michihisa Tsutahara 1) Kazuhiko Ogawa 2) (Graduate School of Science and Technology 1) ,department of Mechanical Engineering 2) , Nada,Koba 657 8501,Kobe University,Japan)

A new type of nozzle which generates two phase water jet as a propulsion device for ships is *** high pressure gas accelerates the two phase fluid by locally generated pressure gradient,Therefore,the principle of accelerating water flow is different from that of jet *** structure of this device is very simple and there is no moving part,Two dimensional open type nozzles have been found effective and intensive studies have been performed to this type of nozzle by experiments and by numerical *** has been clarified that increase of the water flow rate is essential for improving the performance of this *** suitable shape of the nozzle has been *** was also used as the high pressure gas and higher performance was *** is also considered due to increase of the water flow rate because the steam condenses and the gas flow rate dramatically *** tests by model ships support good possibility for applying this device to actual ships.

关键词： propulsion device running test numerical simulation