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71.
The effects of plasma environments on energies, oscillator strengths, polarizabilities and hyperpolarizabilities for lithium atom have been calculated by combining the l-dependent model potential of free lithium atom and linear variation method based on B-spline basis functions. The influence of plasma on lithium atom is represented by the Debye screened potential, which describes effectively the averaged effect of the plasma environment on atomic spectra. The results are in agreement with other reported ones. 相似文献
72.
In this paper, a finite element collocation approach using cubic B-splines is employed for the numerical solution of a generalized form of the nonlinear Klein-Gordon equation. The efficiency of the method is tested on a number of examples that represent special cases of the extended equation including the sine-Gordon equation. The numerical results are compared with existing numerical and analytic solutions and the outcomes confirm that the scheme yields accurate and reliable results even when few nodes are used at the time levels. 相似文献
73.
In this paper, numerical solution of Burgers-Fisher equation is presented based on the cubic B-spline quasi-interpolation. At first, the generalized Burgers-Fisher equation and the cubic B-spline quasi-interpolation are introduced. Moreover, the numerical scheme is presented, by using the derivative of the quasi-interpolation to approximate the spatial derivative of the dependent variable and a low order forward difference to approximate the time derivative of the dependent variable. Moreover, the stability of this method is studied. At last, the numerical results obtained by this way have been compared with the exact solution to show the efficiency of the method. The main advantage of the resulting scheme is that the algorithm is very simple, so it is very easy to implement. 相似文献
74.
In the present paper a numerical method, based on finite differences and spline collocation, is presented for the numerical solution of a generalized Fisher integro-differential equation. A composite weighted trapezoidal rule is manipulated to handle the numerical integrations which results in a closed-form difference scheme. A number of test examples are solved to assess the accuracy of the method. The numerical solutions obtained, indicate that the approach is reliable and yields results compatible with the exact solutions and consistent with other existing numerical methods. Convergence and stability of the scheme have also been discussed. 相似文献
75.
76.
在研究B样条曲线节点的曲率和对应控制点的离散曲率之间关系的基础上,引入了一种新的离散曲率——第二离散曲率的概念,得出了三次均匀B样条曲线节点的曲率和对应控制点的第二离散曲率成正比的结论,并给出了基于第二离散曲率三次均匀B样条曲线的光顺算法.该算法通过直接调整控制点的第二离散曲率进行曲线的光顺,从而使光顺过程更为简洁、更具几何直观性.算例表明,该算法具有较好的光顺效果. 相似文献
77.
The construction of plane elastomechanics and Mindlin plate elements of B-spline wavelet on the interval 总被引:5,自引:0,他引:5
Jiawei Xiang Xuefeng Chen Yumin He Zhengjia He 《Finite Elements in Analysis and Design》2006,42(14-15):1269-1280
Based on two-dimensional tensor product B-spline wavelet on the interval (BSWI), a class of C0 type plate elements is constructed to solve plane elastomechanics and moderately thick plate problems. Instead of traditional polynomial interpolation, the scaling functions of two-dimensional tensor product BSWI are employed to form the shape functions and construct BSWI elements. Unlike the process of direct wavelets adding in the previous work, the elemental displacement field represented by the coefficients of wavelets expansions is transformed into edges and internal modes via the constructed transformation matrix in this paper. The method combines the versatility of the conventional finite element method (FEM) with the accuracy of B-spline functions approximation and various basis functions for structural analysis. Some numerical examples are studied to demonstrate the proposed method and the numerical results presented are in good agreement with the closed-form or traditional FEM solutions. 相似文献
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79.
数字体积相关是通过分析具有相关关系的两组三维图像,获得物体变形过程中位移场和应变场的计算方法。了解该算法在实际噪音下的表现,对这种方法的应用具有十分重要的意义。利用爬山法、最小二乘法,结合三次B样条插值,建立了一套数字体积相关计算方法,用两组具有真实噪音的三维X射线CT数据对该算法进行了系统评测。在没有噪音的理想情况下,该算法的位移误差为0.0065voxel;在真实X-CT噪音的情况下,位移误差增加到0.008voxel,应变误差约为100με。结果表明,本方法可对真实物体变形进行三维位移场、应变场分析。 相似文献
80.
Based on the generalized variational principle and B-spline wavelet on the interval (BSWI), the multivariable BSWI elements with two kinds of variables (TBSWI) for hyperboloidal shell and open cylindrical shell are constructed in this paper. Different from the traditional method, the present one treats the generalized displacement and stress as independent variables. So differentiation and integration are avoided in calculating generalized stress and thus the precision is improved. Furthermore, compared with commonly used Daubechies wavelet, BSWI has explicit expression and excellent approximation property and thus further guarantee satisfactory results. Finally, the effciency of the constructed multivariable shell elements is validated through several numerical examples. 相似文献