共查询到20条相似文献,搜索用时 218 毫秒
1.
用相对论性的DF方法与非相对论性的HF方法分别计算了类锂硅离子能级结构及振子强度、跃迁概率,考查了计算精度,对数值结果进行了理论分析并与其它结果进行了比较。 相似文献
2.
发展了一种三维有限元数值模型和计算方法来对矩形流管声场进行整体的计算.与以往的二维方法相比,此种数值方法不仅全面反映了矩形流管内声波的传播情况,而且提高了网格精度,从而大大扩展了对铺设有声衬的流管的计算领域.结果表明,该数值模型是有效和准确的,与其它方法和文献的计算结果吻合得非常好.同时,在大大增加计算量的同时,也对程序代码进行了优化工作,提高了计算效率. 相似文献
3.
4.
5.
本文利用前文关于非对称陀螺分子带模型参数的数值计算方法,从理论上系统地计算了水分子温度从300K到2000K,波长从1μ到8μ各谱带带模型参数。计算结果与实验值和其它方法算得的结果符合的比较好。 相似文献
6.
电子离子碰撞电离截面是模拟激光等离子体的超热电子的能谱和产额的主要过程之一.基于相对论性的电子离子碰撞的K壳层电离截面理论,计算了Nb、Ag的K壳层和L壳层电子碰撞电离截面,结果和最近的文献实验数值和其它理论数值进行了比较,计算结果比其它模型更加准确,与最近的实验结果也吻合较好,该结果可用来模拟激光等离子体的超热电子能谱和产额. 相似文献
7.
采用磁性液体边界元数值模型分析了磁性粒子微结构磁化状态及相互作用,并与相应的有限元数值结果进行比较.结果表明:虽然粒子边界层附近的磁场分布出现了一定的模糊,且变化幅度明显高于有限元结果,但在粒子边界层以外的其它区域两种数值解法具有高度一致性;当粒子边界元节点数较小时,磁力相互作用边界元结果与有限元结果相差较大,且很不稳定;随着节点数增加,边界元结果逐渐趋近于有限元虚功原理的磁力数值结果,并达到一个较稳定的量值.结果清晰地反映出边界元数值方法在磁性液体多体动力学模拟研究中的一些基本特征。 相似文献
8.
提出了一种求解渐变折射率平板光波导的传播常数和场强分布的数值计算方法,计算了几类典型的渐变折射率波导的传播常数数值,并与其它方法进行了比较,结果表明,该方法计算的精度极高,速度较快,有实用价值. 相似文献
9.
采用半经典近似和数值求和方法,研究了简谐势阱和磁场约束下理想带电费米气体的磁性质,给出了该体系的热力学势、磁场强度和电流密度随外磁场的解析表达式,并分析了约束势阱和磁场对体系的影响.计算结果表明,准经典近似在处理弱场时,与数值计算结果能够得到很好地吻合.该方法和结论可通过相应参量代换过渡到其它形式的受限量子气体. 相似文献
10.
带电粒子在高温等离子体中的减速 总被引:1,自引:0,他引:1
郑春开 《核聚变与等离子体物理》1990,10(3):159-168
本文利用考虑三体效应的量子等离子体动力学方程,推导了带电粒子在高温等离子体中减速公式。对氚核在LiD等离子体和氦核在DT等离子体中的减速作了数值计算,并与其它方法计算结果进行了比较。 相似文献
11.
An exact numerical method for analyzing the propagation properties of leaky modes of inhomogeneous channel optical waveguides with a complex uniaxial diagonal permittivity tensor is developed. The method is based on solving the system of integro-differential equations formulated with respect to transversal components of the magnetic field and the longitudinal component of the electric field. Some results of investigation of leaky modes of diffused channel waveguides in LiNbO3 and LiTaO3 crystals are given. 相似文献
12.
Sound propagation in inhomogeneous waveguides with sound-speed profiles using the multimodal admittance method 下载免费PDF全文
《中国物理 B》2020,(1)
The multimodal admittance method and its improvement are presented to deal with various aspects in underwater acoustics, mostly for the sound propagation in inhomogeneous waveguides with sound-speed profiles, arbitrary-shaped liquid-like scatterers, and range-dependent environments. In all cases, the propagation problem governed by the Helmholtz equation is transformed into initial value problems of two coupled first-order evolution equations with respect to the modal components of field quantities(sound pressure and its derivative), by projecting the Helmholtz equation on a constructed orthogonal and complete local basis. The admittance matrix, which is the modal representation of Direchlet-to-Neumann operator, is introduced to compute the first-order evolution equations with no numerical instability caused by evanescent modes. The fourth-order Magnus scheme is used for the numerical integration of differential equations in the numerical implementation. The numerical experiments of sound field in underwater inhomogeneous waveguides generated by point sources are performed. Besides, the numerical results computed by simulation software COMSOL Multiphysics are given to validate the correction of the multimodal admittance method. It is shown that the multimodal admittance method is an efficient and stable numerical method to solve the wave propagation problem in inhomogeneous underwater waveguides with sound-speed profiles, liquid-like scatterers, and range-dependent environments. The extension of the method to more complicated waveguides such as horizontally stratified waveguides is available. 相似文献
13.
A finite difference beam propagation algorithm based on generalized transmission line equations 总被引:3,自引:0,他引:3
A wide angle beam propagation algorithm is presented, which is based on generalized transmission line (GTL) equations. Besides the discretization, no further approximation is introduced. In principle, a full vectorial analysis is possible, and anisotropic material can be taken into account. The algorithm has been verified for planar 2D-waveguide devices. The wide angle characteristic has been examined by determining the propagation of tilted Gaussian beams in homogeneous media. Further studies were performed for tilted waveguides and for taper structures. Results for the latter devices were compared with other methods showing a very good agreement. 相似文献
14.
M. M. Shabat M. A. Abdel-Naby Y. S. Madi D. Jäger 《International Journal of Infrared and Millimeter Waves》1999,20(4):725-735
We present here two methods of analysis of the complex moving waveguide. One approach is a numerical technique based on Davidenko's method, the other is a perturbation method. Numerical results by Davidenko's method are compared with these obtained from the perturbation method. It is found that the results of the perturbation method are in a good agreement with the numerical one. A comparative study of the propagation and attenuation characteristics of the stationary and moving waveguides has also been investigated and discussed. These results could be used in designing many optical moving sensors. 相似文献
15.
Chuan-Xiu Xu 《中国物理 B》2022,31(9):94301-094301
Models based on a parabolic equation (PE) can accurately predict sound propagation problems in range-dependent ocean waveguides. Consequently, this method has developed rapidly in recent years. Compared with normal mode theory, PE focuses on numerical calculation, which is difficult to use in the mode domain analysis of sound propagation, such as the calculation of mode phase velocity and group velocity. To broaden the capability of PE models in analyzing the underwater sound field, a wave mode calculation method based on PE is proposed in this study. Step-split Padé PE recursive matrix equations are combined to obtain a propagation matrix. Then, the eigenvalue decomposition technique is applied to the matrix to extract sound mode eigenvalues and eigenfunctions. Numerical experiments on some typical waveguides are performed to test the accuracy and flexibility of the new method. Discussions on different orders of Padé approximant demonstrate angle limitations in PE and the missing root problem is also discussed to prove the advantage of the new method. The PE mode method can be expanded in the future to solve smooth wave modes in ocean waveguides, including fluctuating boundaries and sound speed profiles. 相似文献
16.
A numerical method, using the Ritz-Galerkin approach has been applied to the problem of determining the propagation characteristics of inhomogeneous planar optical waveguides. It is shown that very accurate results are obtained for mode spectra and field distributions when compared with the predictions of other exact or approximate methods. 相似文献
17.
针对介质参数及海底边界水平变化波导中的声传播问题,本文基于多模态导纳法提出一种能量守恒且便于数值稳定求解的耦合模态方法.将声压表示为一组正交完备的本地本征函数之和,对声压满足的Helmholtz方程在本地本征函数上作投影,推导出关于声压模态系数的二阶耦合模态方程组.耦合矩阵直观描述水平变化因素对模态耦合的贡献.为避免直接求解二阶耦合模态方程组可能遇到的数值发散问题,将其重构为两个耦合的一阶演化方程组,引入导纳矩阵并使用Magnus数值积分方法获得稳定的声场解.利用该耦合模态方法数值计算水平变化波导中的声场,并与COMSOL参考解比较,结果表明该耦合模态理论能够精确求解水平变化波导中的点源及分布源传播问题. 相似文献
18.
A. Gorin 《Optics Communications》2011,284(8):2164-2167
In this work, we report the fabrication of single-mode Nb2O5 based hybrid sol-gel channel waveguides. Nb2O5 based hybrid sol-gel material has been deposited by spin-coating on silicon substrate and channel waveguides have been fabricated by a UV direct laser writing process. Optical guided modes have been observed to confirm single-mode conditions and optical propagation loss measurements have been performed using the cut-back technique. Optical propagation losses were measured to be 0.8 dB/cm and 2.4 dB/cm at 1.31 μm and 1.55 μm respectively. These experimental results demonstrate low loss optical waveguiding within the infrared range and are very promising in view of material choice for the development of integrated optical devices for telecommunication. 相似文献
19.
The propagation of electromagnetic waves along open periodic, dielectric waveguides is formulated in the case that surface
wave is guided and propagates normally to the corrugation. Our approximate analysis with the propagation characteristics is
to consider a corresponding bounded waveguide problem in which perfect electric or magnetic walls are introduced, and the
periodic corrugation is regarded as consisting of step discontinuities connected by a length of uniform slab waveguide. By
properly taking into account of both surface modes and only a few non-surface-modes, a novel network approach is proposed
for characterizing step discontinuity based on the generalized conservation of complex power technique (GCCPT). Employing
solution selection rule (SSR), we can readily derive propagation characteristics in the Bragg interaction region. A number
of numerical results are shown to demonstrate the usefulness of our approach. 相似文献
20.
Chuan-Lei Jia Ke-Ming Wang Fei Lu Xue-Lin Wang Yi Jiang Lei Wang Yang Jiao Jian-Hua Zhang Xi-Feng Qin Ding-Yu Shen Hong-Ji Ma Rui Nie 《Optics & Laser Technology》2007,39(4):749-753
Single-mode waveguides in LiNbO3 are demonstrated by use of prism coupling method. The waveguides are fabricated by three different energies and single energy C2+ implantations at the equal total doses, respectively. Dark modes and propagation loss are measured by use of prism coupling and moving fiber methods, respectively. Damages produced by implantation are measured by RBS/channeling technique. The waveguide structures are investigated in two different implantation cases. The results of analysis indicate that the heavy ion-implanted waveguides are still defined by synergetic characteristics from both the raised-index region and the low-index barrier. The broadened barrier from multienergy implantation is demonstrated to play a significant role in reducing propagation loss. 相似文献