简介:Fortwotrianglestobecongruent,SAStheoremrequirestwosidesandtheincludedangleofthefirsttriangletobecongruenttothecorrespondingtwosidesandincludedangleofthesecondtriangle.Ifthecongruentanglesarenotbetweenthecorrespondingcongruentsides,thensuchtrianglescouldbedifferent.Itturnsoutthatitispossibletodescribefourcasesinwhichtrianglesarecongruenteventhoughcongruentangles.Fortwotrianglestobecongruent,SAStheoremrequirestwosidesandtheincludedangleofthefirsttriangletobecongruenttothecorrespondingtwosidesandincludedangleofthesecondtriangle.Ifthecongruentanglesarenotbetweenthecorrespondingcongruentsides,thensuchtrianglescouldbedifferent.Itturnsoutthatitispossibletodescribefourcasesinwhichtrianglesarecongruenteventhoughcongruentanglesarenotbetweenthecorrespondingcongruentsides.Suchatheoremcouldbenamed,forexample,SSAtheorem.ManytextsstatethattwotrianglescannotbeshowntobecongruentiftheconditionofSSAexists.However,theauthordescribescasesinwhichsuchtrianglescouldbeprovencongruentwiththeSSAtheorem.Animmediateconsequenceofthisnewunderstandingisthenecessityofrevisingmanyproblemsandanswersinhighschoolandcollege-leveltextsrelatedtocongruenttriangles.arenotbetweenthecorrespondingcongruentsides.Suchatheoremcouldbenamed,forexample,SSAtheorem.Animmediateconsequenceofthisnewunderstandingisthenecessityofrevisingmanyproblemsandanswersinhighschoolandcollege-leveltextsrelatedtocongruenttriangles.
简介:应用SAS/STAT估计非线性回归模型中的参数.首先,通过变量代换,把可以线性化的非线性回归模型化为线性回归模型,并用普通最小二乘法、主成分分析法和偏最小二乘法求模型中的参数和回归模型.其次,通过改良的高斯一牛顿迭代法来估计Logistic模型和Compertz模型中的参数.
简介:研制了二维多介质流体程序,主要包括单介质内高精度流体力学计算,多介质混合网格内各种介质输运过程和压力驰豫平衡过程计算、实际状态方程的黎曼解计算。流体计算分别采用高分辨两步PPM(ParabolicPiecewiseMethod)算法、TVD(TotalVariationDiminishing)算法和FCT(FluxCorrected—Transport)算法,流体界面追踪采用VOF(Volume-of-Fluid)。数值求解可压缩多流体方程组和可压缩VOF方程。二维界面追踪分别采用一阶精度Youngs方法和二阶精度Elivira方法,三维界面追踪采用一阶精度Youngs方法,
简介:严重事故下核电安全壳内由于几何与流动的复杂性,需要有可靠的程序对流动进行分析评估.文章采用符合核电安全标准的开源CFD程序Code_Saturne对壳内气体流动进行计算,主要模拟壳内氢气和水蒸气喷放过程.该过程涉及多组分气体低速流动计算浮力效应引起的分层固体结构热传导结构表面与气体之间的热流和冷凝的计算.该程序使用了SIMPLEC格式并添加了低Mach数气体流动算法,基于理想气体模型的多组分模型和薄板结构上的一维热传导模型.同时,在此基础上改进了壁面函数方法,对壁面进行对流传热和传质流动计算.最后利用两个国际化标准问题对该程序及使用的模型进行了验证.