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| 1 | Design of a new dynamical core for global atmospheric models based on some efficient numerical methods显示文摘A careful study on the integral properties of the primitive hydrostatic balance equations for baroclinic atmosphere is carried out, and a new scheme todesign the global adiabatic model of atmospheric dynamics ispresented. This scheme includes a method of weighted equal-areamesh and a fully discrete finite difference method with quadraticand linear conservations for solving the primitive equationsystem. Using this scheme, we established a new dynamical corewith adjustable high resolution acceptable to the availablecomputer capability, which can be very stable without anyfiltering and smoothing. Especially, some important integralproperties are kept unchanged, such as the anti-symmetries of thehorizontal advection operators and the vertical convectionoperator, the mass conservation, the effective energy conservationunder the standard stratification approximation, and so on. Somenumerical tests on the new dynamical core, respectively regardingits global conservations and its integrated performances inclimatic modeling, incorporated with the physical packagesfrom the Community Atmospheric Model Version 2 (CAM2) of NationalCenter for Atmospheric Research (NCAR), are included. | WANG Bin, WAN Hui, Jl Zhongzhen, ZHANG Xin, YU Rucong, YU Yongqiang & LIU HongtaoState Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China Department of Computational Mathematics, Academy of Mathematics and System Sciences, Peking University, Beijing 100871, China | 2004 | Science China Mathematics2004，47，z1： | 92 |
| 2 | Mechanism of the Spring Persistent Rains over southeastern China显示文摘The Spring Persistent Rains (SPR) in the areas to the south of middle and lower reaches of the Yangtze River or over southeastern China (SEC) is a unique synoptic and climatic phenomenon in East Asia. This study reveals a possible mechanism responsible for the climatic cause of SPR formation through climatic mean data analysis and sensitive numerical model experiments. SEC is located at the down-stream of the southwesterly velocity center (SWVC) which lies on the southeastern flank of the Tibetan Plateau (TP). As a result, there are strong southwesterly wind velocity convergence and moisture con-vergence over SEC. This is the immediate climatic cause of SPR formation. In spring, the seasonal evolution of the southwesterly velocity consists with the surface sensible heating over southeastern TP, indicating that the formation of SPR is related to not only the southwesterly wind of mechanical de-flected flow of TP, but also the southwesterly wind of thermal-forced cyclonic low circulation. Sensitive numerical experiments demonstrate that, without TP, both SWVC and the SPR rain belt will disappear. The southwesterly wind velocity increases almost linearly with the amount of the total diabatic heating with TP rising. Therefore, SWVC is the result of the mechanical forcing and thermal forcing of TP. All these strongly suggest that the presence of TP plays a primary role in the climatic formation of SPR. | WAN RiJin1,2,3 & WU GuoXiong1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Mechanicals (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2 Guangdong Climate and Agrometeorology Center, Guangzhou 510080, China 3 Shanghai Typhoon Institute of China Meterological Administration, Shanghai 200030, China | 2007 | Science China Earth Sciences2007，50，1： | 34 |
| 3 | Numerical simulations of self-propelled swimming of 3D bionic fish school显示文摘Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements. | WU ChuiJie1 & WANG Liang2 1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China 2 Research Center for Fluid Dynamics, People’s Liberation Army University of Science and Technology, Nanjing 211101, China | 2009 | Science China(Technological Sciences)2009，52，3： | 23 |
| 4 | Nonlinear local Lyapunov exponent and atmospheric predictability research显示文摘Because atmosphere itself is a nonlinear system and there exist some problems using the linearized equations to study the initial error growth, in this paper we try to use the error nonlinear growth theory to discuss its evolution, based on which we first put forward a new concept: nonlinear local Lyapunov exponent. It is quite different from the classic Lyapunov exponent because it may characterize the finite time error local average growth and its value depends on the initial condition, initial error, variables, evolution time, temporal and spatial scales. Based on its definition and the at-mospheric features, we provide a reasonable algorithm to the exponent for the experimental data, obtain the atmospheric initial error growth in finite time and gain the maximal prediction time. Lastly, taking 500 hPa height field as example, we discuss the application of the nonlinear local Lyapunov exponent in the study of atmospheric predictability and get some reliable results: atmospheric predictability has a distinct spatial structure. Overall, predictability shows a zonal distribution. Prediction time achieves the maximum over tropics, the second near the regions of Antarctic, it is also longer next to the Arctic and in subtropics and the mid-latitude the predictability is lowest. Particularly speaking, the average prediction time near the equation is 12 days and the maximum is located in the tropical Indian, Indonesia and the neighborhood, tropical eastern Pacific Ocean, on these regions the prediction time is about two weeks. Antarctic has a higher predictability than the neighboring latitudes and the prediction time is about 9 days. This feature is more obvious on Southern Hemispheric summer. In Arctic, the predictability is also higher than the one over mid-high latitudes but it is not pronounced as in Antarctic. Mid-high latitude of both Hemispheres (30°S―60°S, 30°―60°N) have the lowest predictability and the mean prediction time is just 3―4 d. In addition, predictability varies with the seasons. Most regions in the Northern Hemisphere, the predictability in winter is higher than that in summer, especially in the mid-high latitude: North Atlantic, North Pacific and Greenland Island. However in the Southern Hemisphere, near the Antarctic regions (60°S―90°S), the corresponding summer has higher predictability than its winter, while in other areas especially in the latitudes of 30°S―60°S, the prediction does not change obviously with the seasons and the average time is 3―5 d. Both the theoretical and data computation results show that nonlinear local Lyapunov exponent and the nonlinear local error growth really may measure the predictability of the atmospheric variables in different temporal and spatial scales. | CHEN Baohua1, LI Jianping1,2 & DING Ruiqiang2 1. College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China 2. State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | 2006 | Science China Earth Sciences2006，49，10： | 21 |
| 5 | Comparison of the global air-sea freshwater exchange evaluated from independent datasets显示文摘The implied air-sea freshwater flux is examined in two reanalysis datasets provided respectively by European Center for Medium-range Weather Forecasts and National Center for Environmental Prediction. Not only for annual mean state but also for seasonal variation, two reanalyses agree qualitatively well with each other, and both can reproduce reasonably the global distribution of E-P (i.e. Evaporation minus Precipitation). In the view of quantitative comparison, however, remarkable difference has been found on regional scales, especially over the middle and lower latitudes, with some local disagreement exceeding 100 cm/yr. One important difference between current and previous evaluation is the new found net evaporation over the high latitude North Atlantic, which is demonstrated to result from the transient disturbances during boreal winter. | ZHOU Tianjun(State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China) | 2003 | Progress in Natural Science:Materials International2003，13，8： | 21 |
| 6 | EXPERIMENTAL STUDY OF FLOWFIELD STRUCTURE AROUND AN OGIVE-CYLINDER显示文摘The flowfield structure and their aerodynamic characteristics over an ogive cylinder were studied by means of flow visualization and surface pressure measurement in a water tunnel and a wind tunnel. The existence of multi asymmetric vortices over long slender bodies was experimentally confirmed at large angles of attack and in the subcritical Reynolds number range. The spatial 3 D characteristics of the multi vortices system were analyzed and a physical model was developed. The topological structure of different patterns in cross flow plane was studied and the mechanism governing the formation of asymmetric vortices and multi vortices was discussed from the viewpoint of stability of the topological structure. It was concluded that the maximum in the sectional side force distribution curve are not caused by the shedding of higher position vortex, but by the cross over to the symmetric plane of the lower position vortex. | Ph.D.Candidate:Wang Gang Fluid Mechanics Institute, Beijing University of Aeronautics and Astronautics, Beijing 100083, China,Supervisor: Deng Xue ying (Beijing University of Aeronautics and Astronautics) Members of Dissertation Defense Committee: Tong Bing gang (Graduate School of the Chinese Academy of Sciences),Chairman Gu Zhi fu (Peking University) Yang Qi de (China Aerodynamics Research and Development Center) Lv Zhi yong (Beijing University of Aeronautics and Astronautics) Liu Pei qing (Beijing University of Aeronautics and Astronautics) | 2003 | Journal of Hydrodynamics2003，15，5： | 18 |
| 7 | Sensitivity of sea ice and ocean simulations to sea ice salinity in a coupled global climate model显示文摘The impacts of the spatiotemporal variations of sea ice salinity on sea ice and ocean characteristics have not been studied in detail, as the existing climate models neglect or misrepresent this process. To address this issue, this paper formulated a parameterization with more realistic sea ice salinity budget, and examined the sensitivity of sea ice and ocean simulations to the ice salinity variations and associated salt flux into the ocean using a coupled global climate model. Results show that the inclusion of such a parameterization leads to an increase and thickening of sea ice in the Eurasian Arctic and within the ice pack in the Antarctic circumpolar region, and a weakening of the North Atlantic Deep Water and a strengthening of the Antarctic Bottom Water. The atmospheric responses associated with the ice changes were also discussed. | LIU JiPing State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China | 2010 | Science China Earth Sciences2010，53，6： | 15 |
| 8 | Analysis on the decadal scale variation of the dust storm in North China显示文摘In this paper, the temporal variation characteristics of the dust storm in North China are investigated. Based on power spectrum analysis and wavelet analysis, 1956-1970 and 1985-1999 are chosen as the high-frequency and low-frequency dust storm decades respectively. Analysis results clearly show that the spring and wintertime anomalous atmospheric circulation between these two dec-ades are significantly different. Compared with the former decade, there are a strengthened polar vortex, enhanced westerlies near 50°N, and a weak East Asian major though in the winter of the latter decade. The north and center parts of the Siberian high and the Aleutian low become weak. The southerly and easterly wind anomalies appear over the north and east parts of China, which implies the weakening of East Asian winter monsoon. Meanwhile, northern China experiences warmer winters and wetter springs, which are in favor of the weakening of dust storm intensity in North China. There are significant out-of-phase relationships between dust frequency and wintertime westerly intensity, as well as between dust frequency and Arctic Oscillation. It is also found that the frequency of dust weather is strongly re-lated to winter-springtime East Asian monsoon intensity. | KANG Dujuan1,2 & WANG Huijun1 1. NZC/LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100871, China 2. Environmental Fluid Mechanics Laboratory, Stanford University, Stanford CA 94305, USA | 2005 | Science China Earth Sciences2005，48，12： | 14 |
| 9 | Development of the universal and simplified soil model coupling heat and water transport显示文摘It is very important to develop a universal soil model with higher simplicity and more accuracy, which can be widely applied to very general cases such as wet or dry soil, frozen or unfrozen soil and homogeneous or heterogeneous soil. Firstly in this study, based on analysis of both magnitude order and the numerical simulation results, the universal and simplified soil model (USSM) coupling heat and mass transport processes is developed. Secondly, in order to avoid the greater uncertainty caused by the phase change term in numerical iteration process for the model solution obtaining, new version of the universal simplified soil model (NUSSM) is further derived through variables transformation, and accordingly a more efficient numerical scheme for the new version is designed well. The simulation results from the NUSSM agree with the results from more complicated and accurate soil model very well, also reasonably reproduce the observed data under widely real conditions. The new version model, because of its simplicity, will match for the development of land surface model. | LI Qian1,2 & SUN ShuFen1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, China | 2008 | Science China Earth Sciences2008，51，1： | 11 |
| 10 | Influence of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific on the inter-decadal variations of the stratosphere-troposphere exchange of water vapor显示文摘This study investigates the Stratosphere-Troposphere Exchange(STE) of water vapor,emphasizes its interdecadal variations over Asia in boreal summer,and discusses the influences of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific(WNP) on them by using the Wei method with reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) for the years of 1958-2001.The climatology shows that the upward transport of water vapor across the tropopause in boreal summer is the most robust over the joining area of the South Asian Peninsula and Indian-Pacific Oceans(defined as AIPO).The upward transport over there can persistently convey the abundant water vapor into the stratosphere and then influence the distribution and variation of the stratospheric water vapor.The analysis shows that interdecadal variations of the water vapor exchange over the AIPO are significant,and its abrupt change occurred in the mid-1970s and the early 1990s.In these three periods,as important channels of the water vapor exchange,the effect of Bay of Bengal-East Asia as well as South China Sea was gradually weakening,while the role of the WNP becomes more and more important.Further studies show that atmospheric heat sources over the Tibetan Plateau and the WNP are two main factors in determining the interdecadal variations of water vapor exchange.The thermal influences over the Tibetan Plateau and the WNP have been greatly adjusted over the pass 44 years.Their synthesis influences the interdecadal variations of the water vapor exchange by changing the Asian summer monsoon,but their roles vary with time and regions.Especially after 1992,the influence of heat source over the Tibetan Plateau remarkably weakens,while the heat source over the WNP dominates the across-tropopause water vapor exchange.Results have important implications for understanding the transport of other components in the atmosphere and estimating the impact of human activities(emission) on global climate. | ZHAN RuiFen1,2&LI JianPing2 1Shanghai Typhoon Institute of China Meteorological Administration,Shanghai 200030,China 2State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG),Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China | 2008 | Science China Earth Sciences2008，51，8： | 11 |
| 11 | EXPERIMENTAL STUDY ON HIGH-SPEED CENTRIFUGAL PUMPS WITH DIFFERENT IMPELLERS显示文摘The experimental study is carded out on high-speed centrifugal pumps with three different impellers. The ex-perimental results and analysis show that high-speed centrifugal pumps with a closed complex impeller can achieve thehighest efficiency and the lowest head coefficient followed by those with half-open impeller and open-impeller, and canobtain much easily stable head-capacity characrastic curve, while those with a half-open complex impeller can't. Thecharacteristic curve with a open impeller is almost constant horizontal line before dropping sharply. The results also showthat the axial clearance between pump casing and impeller can influence greatly on the performance of centrifugal pumps. | Zhu Zuchao Chen YingState Key Laboratory of Fluid Power Transmission and Control, Zhejiang University,Hangzhou 310027, ChinaHuang Dunhui Jin Qingming Cangnan Special Pumps Co.Ltd of Zhejiang Province | 2002 | Chinese Journal of Mechanical Engineering2002，15，4： | 10 |
| 12 | Physical analysis and numerical simulation for the dynamic behaviour of vehicles in pitching oscillations or rocking motions显示文摘Analytical methods of nonlinear dynamics and numerical simulations for the cou-pling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experi-mental results are cited. The agreement between them is very well. | ZHANG HanXin1,2,3, ZHANG Zhao1,3, YUAN XianXu1,2, LIU Wei1, XIE YuFei1,2 & YE YouDa1,2 1 China Aerodynamics Research and Development Center, Mianyang 621000, China 2 National Laboratory for Computational Fluid Dynamics, Beijing University of Aeronautics and Astronautics, Beijing 100083, China 3 School of Aerospace, Tsinghua University, Beijing 100084, China | 2007 | Science China(Technological Sciences)2007，50，4： | 10 |
| 13 | Force and Flow Structure of an Airfoil Performing Some Unsteady Motions at Small Reynolds Number显示文摘 | Sun Mao Hossein Hamdani (Institute of Fluid Mechanics,Beijing University of Aeronautics & Astronautics) | 2000 | 空气动力学学报2000，18，z1： | 9 |
| 14 | A semi-implicit semi-Lagrangian global nonhydrostatic model and the polar discretization scheme显示文摘The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China Meteorological Administration(CMA).The dynamic framework of GRAPES is featuring with fully compressible equations,nonhydrostatic or hydrostatic optionally,two-level time semi-Lagrangian and semi-implicit time integration,Charney-Phillips vertical staggering,and complex three-dimensional pre-conditioned Helmholtz solver,etc.Concerning the singularity of horizontal momentum equations at the poles,the polar discretization schemes are described,which include adoption of Arakawa C horizontal grid with ν at poles,incorporation of polar filtering to maintain the computational stability,the correction to Helmholtz equation near the poles,as well as the treatment of semi-Lagrangian interpolation to improve the departure point accuracy,etc.The balanced flow tests validate the rationality of the treatment of semi-Lagrangian departure point calculation and the polar discretization during long time integration.Held and Suarez tests show that the conservation proper-ties of GRAPES model are quite good. | YANG XueSheng1,CHEN JiaBin2,HU JiangLin1,CHEN DeHui1,SHEN XueShun1,ZHANG HongLiang1 1 State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China 2 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Beijing 100029,China | 2007 | Science China Earth Sciences2007，50，12： | 9 |
| 15 | First passage failure of dynamical power systems under random perturbations显示文摘The first-passage problem of dynamical power system of a single-machine-infinite-bus (SMIB) system under random perturbations is studied.First,the stochastic averaging method for quasi non-integrable generalized Hamiltonian systems is applied to reduce the equations of the SMIB system under random perturbations to a set of averaged It equations.Then,the backward Kolmogorov equation governing the conditional reliability function and the Pontryagin equation governing the conditional mean of first passage time are established and solved numerically,respectively.Finally,the proposed method is verified by using the Monte Carlo simulation of the original system. | CHEN LinCong1 & ZHU WeiQiu2 1 College of Civil Engineering,Huaqiao University,Xiamen 361021,China 2 Department of Mechanics,State Key Laboratory of Fluid Power Transmission and Control,Zhejiang University,Hangzhou 310027,China | 2010 | Science China(Technological Sciences)2010，53，9： | 9 |
| 16 | Large-eddy simulations of the Richtmyer-Meshkov instability of rectangular interfaces accelerated by shock waves显示文摘A parallel algorithm and code MVFT(multi-viscous-fluid and turbulence) of large-eddy simulation(LES) is developed from our MVPPM(multi-viscous-fluid piecewise parabolic method),and performed to solve the multi compressible Navier-Stokes(N-S) equations.The effect of the unresolved subgrid-scale(SGS) motions on the large scales is represented by different SGS stress models in LES.A Richtmyer-Meshkov instability experiment of the evolution of a rectangular block of SF6,which occupies half of the height of the shock tube test section,following the interaction with a planar shock wave,is numerically and exhaustively simulated by this code.The comparison between experimental and simulated images of the evolving SF6 block shows that they are consistent.The numerical simulations reproduce the complex developing process of SF6 block,which grows overturningly.The geometric quantities that characterize the extents of SF6 block are also compared in detail between numerical simulations and experiment with good agreements between them,a quantitative demonstration of the developing law of SF6 block.There is an evident discrepancy between the three numerical simulations for the maximum position of the right edge of block at the late stage,because the right interface grows complicated and the dissipation is different for different SGS models.The SGS turbulent dissipation,molecular viscosity dissipation and SGS turbulent kinetic energy have been studied and analyzed.They have a similar distribution to the large eddy structures.The SGS turbulent dissipation is much greater than the molecular viscosity dissipation;the SGS turbulent dissipation of Vreman model is smaller than the Smagorinsky model.In general,the simulated results of Vreman SGS model are better compared with the dynamic viscosity and Smagorinsky SGS model.The vorticity and circulation deposition on the block interface have also been investigated. | WANG Tao,BAI JingSong,LI Ping & LIU Kun Institute of Fluid Physics,China Academy of Engineering Physics,Mianyang 621900,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，5： | 8 |
| 17 | Flow structures in flat plate boundary layer induced by pulsed plasma actuator显示文摘The flow field in the flat plate boundary layer induced by the pulsed plasma actuator was simulated by solving the Navier-Stokes equations with a phenomenological DBD plasma model. The effects of actuation strength,wave form and frequency on the flow structures induced by the unsteady pulsed plasma actuator were investigated. The results indicated that a series of vortex pairs were formed in the boundary layer,and decayed in downstream convection following the exponential law. The strength of vortex pair was dominated by the effective plasma actuation strength,and the vortex streamwise spacing depended on the actuation frequency. If the duty cycle is not so large that interaction of adjacent vortex pairs can be negligible,then the actuation wave form has little influence on the vortex pair induced by the unsteady plasma actuator. | ZHANG PanFeng1,2, LIU AiBing1 & WANG JinJun1,2 1Institute of Fluid Mechanics, Beijing University of Aeronautics and Astronautics, Beijing 100191, China 2Key Laboratory of Fluid Mechanics, Ministry of Education, Beijing 100191, China | 2010 | Science China(Technological Sciences)2010，53，10： | 8 |
| 18 | Optimization design study of low-Reynolds-number high-lift airfoils for the high-efficiency propeller of low-dynamic vehicles in stratosphere显示文摘Aerodynamic performance of low-Reynolds-number high-lift airfoil makes a great impact on designing a high-efficiency propeller for low-dynamic vehicles in stratosphere. At high altitude,low-Reynolds-number airfoils are supposed to have high lift-drag ratio or high endurance factor at cruising attack angle along with good stall characteristics. To design such a high-performance low-Reynolds-number high-lift airfoil,the paper established a hierarchical multi-objective optimization platform by combing direct search optimization algorithm EXTREM and airfoil flow field solver XFOIL to automatically and quickly calculate aerodynamic performance function of airfoil by computer. It provides an effective solution to multi-point design problem of low-speed low-Reynolds-number airfoil. It can be seen from the results of three typical optimization examples,the new airfoil E387_OPT2,FX63-137_OPT2 and S1223_OPT2 based on hot low-Reynolds-number high-lift airfoils (Eppler 387 airfoil,Wortmann FX63-137 airfoil and S1223 airfoil) can meet the optimization design requirements and have very good aerodynamic characteristics in both design state and non-design state. Thus,the applicability and effectiveness of hierarchical multi-objective optimization platform are verified. | MA Rong1, ZHONG BoWen2 & LIU PeiQing1 1 Key Laboratory of Fluid Mechanics, Ministry of Education, Institute of Fluid Mechanics, School of Aeronautical Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China 2 Department of Aerospace Science, School of Engineering, Cranfield University, MK43 0AL, United Kingdom | 2010 | Science China(Technological Sciences)2010，53，10： | 7 |
| 19 | Numerical and experimental investigation of the fracture behavior of shock loaded alumina显示文摘Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A ve-locity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit and the free surface velocity profile,which consists of an elastic wave followed immediately by a dispersive inelastic wave. The stress histories under different impact velocities are measured by in-material manganin gauges. Based on the experimental data a Hugoniot curve is fitted,which shows the compressive characteristics that alumina changes typically from elastic to 'plastic' ,and under higher pressure it will be transferred to similar-fluid state. The turning point of the Hugoniot curve from a high pressure region to a low pressure region is about 11.4 GPa. The fracture process of alumina is simulated by way of finite element code. After the analysis of the fracture mechanism,the numerical results show an important role played by the nucleation and the growth of the cracks in the macro-scopic fracture of the alumina target. The numerical predictions of stress histories are compared with the experimental results,which indicates consistency between them. | REN HuiLan1,SHU XueFeng2 & LI Ping3 1 State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,Beijing 100081,China 2 Institute of Applied Mechanics and Biomedical Engineering,Taiyuan University of Technology,Taiyuan 030024,China 3 Labroratory for Shock Wave and Detonation Physics Research,Institute of Fluid Physics,CAEP,Mianyang 610059,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，2： | 7 |
| 20 | Change in the tilting of the ridgeline surface of the subtropical anticyclone and the predictability of the onset of the Asian summer monsoon显示文摘The NCEP/NCAR reanalysis data are used tostudy the relationships among the change in the tilting of theridgeline surface of the subtropical anticyclone, the estab-lishment of the so-called 'seasonal transition axis (STA)' andthe onset of the Asian summer monsoon. It is shown that themonsoon onset is characterized by the overturning of themeridional temperature gradient (MTG) in the vicinity of theridgeline surface. A MTG index is then constructed to inves-tigate the predictability of the Asian summer monsoon onsetconceptually. Data diagnoses show that if the initial MTG isknown and the meridional gradient across the ridgeline sur-face of the local temperature tendency can be estimated, alate or early onset of the summer monsoon can be qualita-tively predicted in advance. | MAO Jiangyu, DUAN Anmin, LIU Yimin WU Guoxiong State Key Laboratory of Numerical Modeling for Almospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | 2003 | Chinese Science Bulletin2003，48，S2： | 6 |
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