排序方式: 共有50条查询结果,搜索用时 15 毫秒
11.
1把半圆弧六等分,以这些分点(包括直径的两端点)为顶点可作多少个钝角三角形? (A) 15;(B)20;(C)25;(D)30. 2乒乓球运动员n人,其中男运动员5人,女运动员6人,从这n个运动员中选出4人,举行男女混合双打比赛,选法的种数是 (A)C号C丢;(B)P孔P丢;(C)C孔P丢;(D)C邑C邑I,二 3由l、2、3、4四个数字组成的所有没有重复数字的三位数的数字和是 (A) l8();(B)36();(C)540;(D)720. 4以正方体的顶点作四面体,可以作几个? (A)58;(B)62;(C)64;(D) 70.附:上期本栏揭底1.(C);2.(B卜3.(B).排列组合选择题四道@蒋涛$江苏滨海中学~~… 相似文献
12.
动态硫化EPDM/PP共混体系中PP相的结晶度及晶体结构的研究 总被引:3,自引:0,他引:3
研究了动态硫化EPDM/PP共混物中PP相的结晶度及晶体结构,同时讨论了制备工艺条件以共混物中PP相的结晶度和晶体结构的影响。结果表明:在动态硫化EPDM/PP共混物中,硫化的EPDM的分子键没有穿入PP的晶区,PP的结晶度随EPDM含量的增加而下降。提高共混温度,加入软化剂或碳黑均使共混物中PP的结晶度降低,共混时间15min时,共混物中PP相的结晶度最低,但PP的晶格不受制备工艺条件的影响。 相似文献
13.
14.
A local refinement purely meshless scheme for time fractional nonlinear Schrodinger equation in irregular geometry region 下载免费PDF全文
A local refinement hybrid scheme(LRCSPH-FDM)is proposed to solve the two-dimensional(2D)time fractional nonlinear Schrodinger equation(TF-NLSE)in regularly or irregularly shaped domains,and extends the scheme to predict the quantum mechanical properties governed by the time fractional Gross-Pitaevskii equation(TF-GPE)with the rotating Bose-Einstein condensate.It is the first application of the purely meshless method to the TF-NLSE to the author’s knowledge.The proposed LRCSPH-FDM(which is based on a local refinement corrected SPH method combined with FDM)is derived by using the finite difference scheme(FDM)to discretize the Caputo TF term,followed by using a corrected smoothed particle hydrodynamics(CSPH)scheme continuously without using the kernel derivative to approximate the spatial derivatives.Meanwhile,the local refinement technique is adopted to reduce the numerical error.In numerical simulations,the complex irregular geometry is considered to show the flexibility of the purely meshless particle method and its advantages over the grid-based method.The numerical convergence rate and merits of the proposed LRCSPH-FDM are illustrated by solving several 1D/2D(where 1D stands for one-dimensional)analytical TF-NLSEs in a rectangular region(with regular or irregular particle distribution)or in a region with irregular geometry.The proposed method is then used to predict the complex nonlinear dynamic characters of 2D TF-NLSE/TF-GPE in a complex irregular domain,and the results from the posed method are compared with those from the FDM.All the numerical results show that the present method has a good accuracy and flexible application capacity for the TF-NLSE/GPE in regions of a complex shape. 相似文献
15.
16.
17.
18.
本文提出了一种核梯度改进光滑粒子动力学(KGC-SPH)方法,模拟了黏性液滴形变自由表面问题.首先,通过模拟等温黏性液滴拉伸和旋转变形,验证了KGC-SPH法较SPH法具有较高精度和更好稳定性,且能很好地保持总角动量守恒.其次,基于非等温van der Waals模型对平衡态圆形液滴的形成过程进行数值研究,观察到小幅度振荡现象,并给出了一种新的克服张力不稳定性的方法和一种适合KGC-SPH方法的新的表面张力处理技术.最后,研究了van der Waals液滴的周期性振荡现象,讨论了初始椭圆形液滴长短半轴比
关键词:
光滑粒子动力学
黏性液滴
van der Waals模型
表面张力 相似文献
19.
20.
巧妙构造腰为1的等腰三角形来求一些三角式的值, 例冬求形象直观,饶有趣味。cOS了一“。s了的值。解·作△ABC,使AB=Bc二取匕A二乙C二二/5,则Ae二2。。s晋,·延长AB至D,使DC=刀U二1,由乙DBC=乙BDC=2二/5,则乙ADC=:ACD,且BD一ZcOS争,AC二A”=AB+BD,即Zcos晋=,+Zcos譬,2成1一犷 一一2兀cOS晋一考例,求。。s今+。。5誓+一夸的值· 解作△ABC,使乙A二二/7,ABBC二刃C=1,=才. 在乙ABC内作艺CBD二2二/7, 月_仄心‘了尹琪c_则月刀=DB二1一x. 在△A刀C中,由余弦定理得x一2o 一一cos夸·2一xZ 2cos了3兀在△BCD中得cos今 … 相似文献