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A nonlinear Galerkin/ Petrov- least squares mixed element (NGPLSME) method for the stationary Navier-Stokes equations is presented and analyzed. The scheme is that Petrov-least squares forms of residuals are added to the nonlinear Galerkin mixed element method so that it is stable for any combination of discrete velocity and pressure spaces without requiring the Babuska-Brezzi stability condition. The existence, uniqueness and convergence ( at optimal rate ) of the NGPLSME solution is proved in the case of sufficient viscosity ( or small data). 相似文献
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IntroductionThenonlinearGalerkinmethodisamulti_levelschemetofindtheapproximatesolutionforthedissipativePDE .ThismethodhasfirstmainlybeenaddressedbyFoias_Manley_Temam[1],Marion_Temam[2 ],Foias_Jolly_Kevrekidis_Titi[3]andDevulder_Marion_Titi[4 ]inthecaseofspect… 相似文献
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The IAP two-level atmospheric general circulation model was coupled to a 60-m-deep mixed layer ocean model and a zero-layer thermodynamic model to simulate the climatic effects induced by a doubling of CO_2 concentration in the atmosphere.The global surface temperature is 1.75℃ when CO_2 is doubled. This value is lower than most of other results in the world, such as those of GFDL, NCAR, UKMO, GISS and OSU models.There are large regional and seasonal differences in the climatic change. Great warming is found in the Northern Hemisphere's high-latitude region anti the Antarctica; and the warming in land areas is greater than in ocean areas, while the precipitation increases in high latitudes and tropical regions but decreases in subtropical regions. In both hemispheres, the warming is greater in winter than in other seasons. As for the changes in China, we find that the precipitation in southwestern and northern China greatly decreases in summer but increases in winter. 相似文献
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CO_2含量加倍引起的气候变化的数值模拟研究 总被引:5,自引:0,他引:5
在本工作中,大气物理所两层全球大气环流模式同60m深的混合层海洋模式及热力学海冰模式耦合起来,模拟了现代气候(1×CO_2)及CO_2含量加倍后的气候,进而研究了CO_2含量加倍后引起的全球气候变化。CO_2含量加倍后,全球表面气温上升1.75℃。模拟出的气候变化存在着很大的区域差异和季节差异,北半球高纬区和南极区增温幅度较大。而陆地区域的增温幅度又大于海洋区域的增温幅度;降水在热带及高纬区一般是增多而副热常区一般减少。另外,两个半球均是冬季增暖强一些。中国西南和华北地区夏季降水减少,而冬季增多。 相似文献
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上海光源二期工程建设计划研制一台多极超导扭摆器用于生物医学的X射线成像及治疗。该多极超导扭摆器由21对NbTi超导线圈组成,磁极气隙为22mm,在储存环束流电子能量为3.5GeV时其特征能量为33keV,覆盖的能量范围为20keV到120keV,可用于K边吸收成像、衍射增强成像、相衬成像、CT和微束放射治疗。文中的主要内容为一个具有21个磁极,周期长度为140mm,气隙中心磁感应强度为4.2T的多极超导扭摆器的磁场设计,包括磁极和线圈的参数设计、端部结构和周期磁场的积分场设计,以及简要的超导线圈应力应变分析。 相似文献
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