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81.
The moving least-square approximation is discussed first. Sometimes the method can form an ill-conditioned equation system,
and thus the solution cannot be obtained correctly. A Hilbert space is presented on which an orthogonal function system mixed
a weight function is defined. Next the improved moving least-square approximation is discussed in detail. The improved method
has higher computational efficiency and precision than the old method, and cannot form an ill-conditioned equation system.
A boundary element-free method (BEFM) for elastodynamics problems is presented by combining the boundary integral equation
method for elastodynamics and the improved moving least-square approximation. The boundary element-free method is a meshless
method of boundary integral equation and is a direct numerical method compared with others, in which the basic unknowns are
the real solutions of the nodal variables and the boundary conditions can be applied easily. The boundary element-free method
has a higher computational efficiency and precision. In addition, the numerical procedure of the boundary element-free method
for elastodynamics problems is presented in this paper. Finally, some numerical examples are given. 相似文献
82.
层流中固体颗粒运动方程的初值问题解的存在唯一性表明悬浮颗粒在圆管层流人口段剪切区中的运动,由进入该区的颗粒初始状态(初始位置和初始速度)确定,其运动轨迹也由该初始状态唯一确定。层流中固体颗粒运动方程稳定性分析表明达到稳定状态的颗粒必定满足条件:up=uf(∞,c),up=0,Re(α/R)2(c/R)<2.8728. 相似文献
83.
Zhan-jie SONG Wen-chang SUN Shou-yuan YANG & Guang-wen ZHU School of Science Tianjin University Tianjin China Department of Mathematics LPMC Nankai University Tianjin China National Ocean Technology Center Tianjin China 《中国科学A辑(英文版)》2007,50(4):457-463
We show that a weak sense stationary stochastic process can be approximated by local averages. Explicit error bounds are given. Our result improves an early one from Splettstosser. 相似文献
84.
Continuous counter-current chromatographic separation has been carried out in a simulated moving bed system (SMB). We have worked with a SMB pilot plant (8 columns, 4.4 litres of resin each) which allows the continuous withdrawal of two different fractions. A mixture of glucose-fructose has been separated. To calculate the concentration profile within the separator an axial dispersed plug flow model and an equilibrium stage model have been employed; software has been created to simulate the behaviour of the separator. The necessary parameters of the mode: the adsorption equilibrium constant, the height equivalent to a theoretical plate and the bed voidage, have been acquired experimentally from elution chromatography measurements. The results calculated by simulation give a good representation of the experimental concentration profiles; other separations like xylitol-arabitol have been simulated. The influence of some factors like desorbent flow-rate, feed flow-rate and the bed voidage have been studied using the software. Once the system has worked in a two withdrawal way, an extension of the pilot plant has been constructed so as to obtain a third one. The necessary parameters of the three withdrawal model will be studied. 相似文献
85.
Haobin Yang Ziyu Wang Zhifeng Tu Junjie Jiang Danlin Xu Zhenwu Mo Haiqi Huang Dongmei Deng 《Annalen der Physik》2023,535(9):2300167
This paper analytically and numerically proposes the propagation dynamics of the symmetric Pearcey Gaussian vortex beam (SPGVB) in the uniformly moving parabolic potential. The optical vortex located in the initial plane produces a vortex channel in the presence of the uniformly moving parabolic potential, called the vortex trajectory. The vortex trajectory can be manipulated dynamically by configuring different combinations of the parameters, and the optical intensity and the focal position can also be affected. Moreover, the spatial dynamic vortex trajectory is derived analytically, and the 2D on-axis and off-axis vortex scenarios are also presented. Our work expands the methods of the vortex trajectory manipulation and may broaden more practical potential applications in the particle manipulation. 相似文献
86.
87.
二维振荡叶栅非定常粘性流动数值模拟 总被引:9,自引:0,他引:9
采用显式四步Runge-Kutta格式,结合Baldwon-Lomax紊流模型求解Navier-Stokes方程,借助运动网格技术,完成了对二维振荡叶栅非定常粘性流动的数值模拟。为了加速求解过程,引入了变系数隐式残差光顺方法,取得了较好效果。数值结果与已公布的数据有很好的一致性。 相似文献
88.
惯导系统动基座传递对准技术综述 总被引:30,自引:8,他引:30
以国外有关献为依据,介绍了传递对准技术研究的历史,分析和归纳了传递对准匹配方法、对准精度提高方法、结构挠曲运动补偿方法,介绍了机动运动、算法、模型、仿真和实验等方面的研究进展情况以及传递对准技术研究中所遇到的困难,并提出克服这一困难的基本途径,探讨了研究的发展方向。 相似文献
89.
自抗扰控制技术在捷联惯导动基座初始对准中的应用研究 总被引:1,自引:1,他引:1
提出并设计了应用自抗扰控制技术(ADRC)的捷联惯性系统动基座初始对准方案。通过数字仿真,将卡尔曼滤波与自抗扰控制的性能进行了详细的比较,证明该方法具有对准时间快,精度高,抗干扰能力强等特点。 相似文献
90.
本文给出了求解一类相当普遍的三维运动接触问题的分析解法,并且把仅仅对静态接触问题成立的 定理推广到动力学情形,作了严格证明。作为例子,对接触区为椭圆的情形给出了积分形式的解,并且作了数值计算,由这些结果可以看出运动压体速度的效应。 相似文献