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941.
The finite-thickness model (FTM) is applied to the design of cylindrical microlenses based on the wave-front interference principle, rather than the existing zero-thickness model (ZTM). This design method is very simple in physics and highly efficient in computations. For cylindrical lenses with different f-numbers (from f/1.5 to f/0.6), the detailed designs by using both the FTM and the ZTM are carried out. To show the superiority of the FTM to the ZTM, we investigate the focal performance of all the designed lenses based on rigorous electromagnetic theory and the boundary element method. Numerical results reveal that the constructed cylindrical lenses by the FTM are witnessed to exhibit much better focusing performance than those by the ZTM, especially for the small f-numbers. 相似文献
942.
GAO Ji-mei LI Wen-hua 《数学季刊》2007,(3)
The main aim of this paper is to have an accurate analysis on the famous Adini's element for the second order problems under to the anisotropic meshes.We firstly show that the interpolation of Adini's element satisfy the anisotropic property.Then the optimal error estimate is obtained without the regularity assumption on the meshes. 相似文献
943.
944.
945.
946.
Antoni Torrens 《Mathematical Logic Quarterly》1994,40(4):431-444
In this paper we characterize the MV-algebras containing as subalgebras Post algebras of finitely many orders. For this we study cyclic elements in MV-algebras which are the generators of the fundamental chain of the Post algebras. Mathematics Subject Classification: 03G20, 03G25, 06D25, 06D30, 06F15, 06F35. 相似文献
947.
How well do discrete element granular flow models capture the essentials of mixing processes? 总被引:9,自引:0,他引:9
Flowing granular materials, undergoing both mixing and segregation, play important roles in industries ranging from minerals and food to pharmaceuticals and ceramics. Sometimes it is desirable to enhance the mixing and inhibit segregation and in other cases it is desirable to minimise the mixing and enhance the segregation. The fundamentals of these processes are poorly understood. Computational modelling of such granular flows offers a good opportunity to study these fundamentals. But how well do these discrete element based modelling techniques capture the essential features of mixing processes? The capabilities of our discrete element modelling package are described. Two different methods for measuring the rates of mixing are presented and three different configurations are studied. Qualitatively reasonable flows are obtained. A detailed study of the mixing demonstrates that the amount and nature of the mixing is quite sensitive to a range of physical parameters. 相似文献
948.
Yuzuru Eguchi 《国际流体数值方法杂志》2003,41(8):881-904
A new regularization method is proposed for the Galerkin approximation of the incompressible Navier–Stokes equations with Q1/P0 element, by newly introducing a square‐type linear form into the variational divergence‐free constraint regularized with the global pressure jump (GPJ) method. The addition of the square‐type linear form is intended to eliminate the hydrostatic pressure mode appearing in confined flows, and to make the discretized matrix positive definite and then non‐singular without the pressure pegging trick. Effects of the free parameters for the regularization on the solutions are numerically examined with a 2‐D driven cavity flow problem. Furthermore, the convergences in the conjugate gradient iteration for the solution of the pressure Poisson equation are compared among the mixed method, the GPJ method and the present method for both leaky and non‐leaky 3‐D driven cavity flows. Finally, the non‐leaky 3‐D cavity flows at different Re numbers are solved to compare with the literature data and to demonstrate the accuracy of the proposed method. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
949.
喻德科 《光谱学与光谱分析》1992,12(5):111-114
本文提出用微晶纤维素与GSD等国家一级系列标样按不同比例混合制备标准样品。油页岩样品不经前处理,直接粉末法压片,经验系数法校正元素间效应,直接测定油页岩中V、Co、Ni、Cr、Cu、Zn、Sr、Ba和Rb等元素的X射线荧光光谱法。样品分析结果与ICP-AES法分析结果基本一致,本法具有简单、准确、实用的特点。 相似文献
950.
微量元素与眼底病 总被引:3,自引:1,他引:2
张振宇 《广东微量元素科学》1995,2(2):1-4
目前已知有十多种微量微元素与眼的正常生理功能有密切关系。且对多种眼病的发生有很大影响,本文综合介绍微量元素锌、铜、硒与视觉功能的密切关系,以及近年来在脉络膜,视网膜、视神经的几种疾病中有关锌、铜、硒的测定研究进展。 相似文献