通信车天线布局仿真设计模型的可视化研究

通信车天线布局仿真设计模型的可视化是几何建模、模型验证和电磁兼容分析的重要手段。该文提出了由面单元着色、面单元外法矢量显示、面单元及线单元编号显示构成的模型可视化的模式。针对面单元着色，提出了余数配色法；针对面单元外法矢量显示，推导出面单元质心、外法矢量方向、外法矢量终点三个要素的计算公式；针对单元编号的显示，提出了面单元及线单元编号显示的方法。实践表明，该文提出的方法具有满意的可视化效果并可推广应用于其他领域。     

A comparison of various mixed-interpolation finite elements in the velocity-pressure formulation of the Navier-Stokes equations

It is generally recognized that mixed interpolation should be used in the velocity-pressure finite element formulation of incompressible viscous flow problems. In this paper, four types of mixed interpolation elements are considered and compared. These are namely: six-node triangular elements, eight-node serendipity elements, nine-node Lagrangian elements and four-node quadrilateral elements. The comparison is made via two numerical examples concerning steady flow through a sudden expansion and steady free thermal convection in a square cavity. Results indicate that for the same number of pressure unknowns, serendipity elements can give considerably less accurate pressure fields than most other types of elements. Lagrangian elements give the most accurate pressure and velocity distributions. The numerical performance of triangular elements is intermediate in accuracy and is dependent on the triangular pattern used. Finally, the four-node element may generate spurious pressure modes depending on the boundary condition specifications.     

招贴设计“硬要素”与“软要素”的解析与构建

一张优秀的招贴设计,包含了"硬要素"即具象要素与"软要素"即抽象要素之间和谐构建的关系,解析其视觉语言对于探索招贴的视觉语义具有重要意义。文章着重从以下三方面来解析招贴的视觉语言:1.招贴设计的"硬要素"解析并探索其基础性作用;2.招贴设计的"软要素"分析并研究其主观能动性拓展;3.招贴设计"硬要素"与"软要素"的和谐处理并构建其整合的视觉语义,打造"形神兼备"的优秀招贴设计作品。     

一类论域函数的全性与极大性

该文研究L－论域上稳定函数的全性与极大性,由于全函数在计算机科学与技术中是不多见的,因此作者从降低函数全性的要求出发,转而要求函数是关于一类元素是全的,即将这类元素仍然映射成该类元素,另一方面,论域中元素间的序关系反映了元素包含信息多少的关系,因此包含尽可能多信息的元素,即极大元素是重要的一类元素,该文引入了极大类全函数,即将极大元映射成极大元的函数,重点研究极大类稳定全函数,同时关注稳定映射关于稳定序的极大性,即极大稳定函数,结果表明在一类的L－论域上,极大类稳定全函数与极大稳定函数是一致的。     

The use of 2D enriched elements with bubble functions for finite element analysis

In this paper, the concept that adds the interior nodes of the Lagrange elements to the serendipity elements is described and a family of enriched elements is presented to improve the accuracy of finite element analysis. By the use of the static condensation technique at the element level, the extra computation time in using these elements can be ignored. Plane stress problems are used as examples in this paper. The numerical results show that these enriched elements are more accurate than the traditional serendipity elements. The convergence rate of the proposed elements is the same as the traditional serendipity elements. The error norm of the second and third order proposed elements can be reduced from 40% to 60% when compared with the use of the traditional serendipity elements. In the numerical examples, the use of the second and third order proposed elements not only give an improvement in element accuracy but also save computation time, when the precondition conjugate gradient method is used to solve the system of equations. The saving of computation time is due to the decrease of iteration number in iteration method.     

Topology optimization using B-spline finite elements

Topology optimization algorithms using traditional elements often do not yield well-defined smooth boundaries. The computed optimal material distributions have problems such as ??checkerboard?? pattern formation unless special techniques, such as filtering, are used to suppress them. Even when the contours of a continuous density function are defined as the boundary, the solution can still have shape irregularities. The ability of B-spline elements to mitigate these problems are studied here by using these elements to both represent the density function as well as to perform structural analysis. B-spline elements can represent the density function and the displacement field as tangent and curvature continuous functions. Therefore, stresses and strains computed using these elements is continuous between elements. Furthermore, fewer quadratic and cubic B-spline elements are needed to obtain acceptable solutions. Results obtained by B-spline elements are compared with traditional elements using compliance as objective function augmented by a density smoothing scheme that eliminates mesh dependence of the solutions while promoting smoother shapes.     

A new method for assembly line balancing having stochastic work elements

The main feature of the method suggested in this paper is the assignment of priority to elements and priority elements are preferred to non-priority elements when assigning elements to stations. It accepts element times from known or unknown symmetrical distributions, minimizes the variation within a station and allows assignments of elements to stations such that each station time does not exceed the probability confidence levels set by management.     

Three- and four-noded planar elements using absolute nodal coordinate formulation

This paper investigates two new types of planar finite elements containing three and four nodes. These elements are the reduced forms of the spatial plate elements employing the absolute nodal coordinate approach. Elements of the first type use translations of nodes and global slopes as nodal coordinates and have 18 and 24 degrees of freedom. The slopes facilitate the prevention of the shear locking effect in bending problems. Furthermore, the slopes accurately describe the deformed shape of the elements. Triangular and quadrilateral elements of the second type use translational degrees of freedom only and, therefore, can be utilized successfully in problems without bending. These simple elements with 6 and 8 degrees of freedom are identical to the elements used in conventional formulation of the finite element method from the kinematical point of view. Similarly to the famous problem called “flying spaghetti” which is used often as a benchmark for beam elements, a kind of “flying lasagna” is simulated for the planar elements. Numerical results of simulations are presented.     

Explicit formulation of two anisotropic,triangular, thin,shallow shell elements

The derivation and assessment of two anisotropic, triangular, thin, shallow shell elements is presented. Flexure in these elements is based on two simple, effective triangular plate elements. DKT and E-1, so that the resulting stiffness matrices can be obtained explicitly. Numerical examples compare these new shell elements with the high-precision element based on the T-18 bending triangle. FORTRAN listings are provided to assist implementation of the elements.     

FC—Index：一种压缩XML数据的索引结构

如何迅速、有效地进行XML数据查找,关键问题是避免对无关元素进行查询.通过合并元素,可以减少文档中元素的数目,同时还能够避免查找冗余结点,有效提高查询效率.提出一种基于Ctree的新索引结构FC-Index,它通过合并结构中"相同"元素压缩结构,从而在查询过程中过滤掉与查找无关的元素.基于FC-Index索引结构提出一种新的查询方法,能够有效地针对FC-Index进行快速查找.     

高精度臭灵丹微量元素含量检测系统设计

为了实现快速、无损、实时检测和分析臭灵丹中微量元素的含量,现对高精度臭灵丹微量元素检测系统进行设计。使用当前方法检测臭灵丹时,无法在保证微量元素活性的条件下提取微量元素。为此,提出一种基于Taguchi的高精度臭灵丹微量元素含量检测系统设计方法。该方法使用日本理学ZSX100型X射线荧光光谱仪采集臭灵丹微量元素光谱,确定微量元素种类,利用超临界萃取技术中的两大技术超临界流体萃取技术和超临界固体萃取技术萃取出臭灵丹中的微量元素,再经过超滤分离法中直线段、曲线段、水平段三个阶段分离出萃取液中微量元素,以ICP-MS法计算出微量元素的含量,达到对臭灵丹中微量元素含量的高精度检测。实验仿真证明,所提方法可以快速、无损、实时检测和分析臭灵丹中微量元素。     

飞机蒙皮拉形模拟中上压模具网格的生成技术

为了解决飞机蒙皮拉形有限元仿真中上压模具(简称上模)与下模具(简称下模)型面网格间的协调问题,提出了以切割下模网格、调整不良网格、生成圆角和侧壁、单元与节点重新编号、网格厚向偏移等为主要步骤的上模网格生成过程.在切割下模网格时,根据被切型面网格的节点及其所在单元相对于切割平面的位置来判断该单元是否属于上模网格,并对单元与节点进行相应处理;对切割后的不良网格进行了形状与法向的调整,并在网格切割线位置按照给定宽度生成圆角单元,按给定的最大高度及高度方向上的单元数量生成侧壁单元;采用图论法对节点及单元重新编号,再按照零件厚度沿网格的法向进行网格偏移.对复杂的S形蒙皮、进气道蒙皮和翼身融合蒙皮的上模网格模型的生成进行验证的结果表明,采用文中提出的生成过程与方法能够顺利地生成与下模网格面相协调的上模网格.     

Adaptive refinement analysis using hybrid-stress transition elements

In this paper, 4-node to 7-node hybrid-stress transition elements are developed for automatic adaptive refinement analysis of plane elasticity problems. The displacement-based transition quadrilateral elements are first adopted and applied to refinement analysis using both full and reduced integration schemes. As the stress field over the displacement-based transition elements is not continuous, a more smooth stress pattern is desirable and could enhance the performance of the element. Indeed, continuous stress field of various orders can be easily introduced into a displacement-based element through a variational procedure based on the Hellinger–Reissner functional. Of the same kinematics and displacement pattern, the resulting hybrid-stress transition elements are more superior to the displacement-based elements in possessing a more continuous high quality stress field within the element. The hybrid-stress transition elements are tested with classical benchmark examples, and the results indicate that hybrid-stress transition elements are consistently more efficient than the displacement-based counterparts in adaptive refinement analysis. A more economical rank-deficient version of hybrid-stress transition elements is also available. While they are less expensive to evaluate, they enjoy a very similar convergence rate as the rank-sufficient hybrid-stress transition elements.     

集成主板芯片组新贵——nVIDIA C51芯片组抢先测试

从开发工控软件的角度,介绍了使用面向对象方法开发工控软件流程图画面的设计思想和设计方法,对工控软件流程图面向对象设计中的图元类、图元库类、动画连接、图元组合以及快速显示、无闪烁显示等要素进行了阐述.     

Geometrically non-linear formulation for the three dimensional solid-shell transition finite elements

This paper presents a geometrically non-linear formulation using total lagrangian approach for the solid-shell transition finite elements. Such transition finite elements are necessary in geometrically non-linear analysis of structures modelled with three dimensional solid elements and the curved shell elements. These elements are an essential connecting link between the solid elements and the shell elements. The element formulation presented here is derived using the properties of the three dimensional solid elements and the curved shell elements. No restrictions are imposed on the magnitude of the nodal rotations. Thus the element formulation is capable of handling large rotations between two successive load increments. The element properties are derived and presented in detail. Numerical examples are also presented to demonstrate their behavior, accuracy and applications in three dimensional stress analysis.

It is shown that the selection of different stress and strain components at the integration points do not effect the overall linear response of the element. However, in geometrically non-linear applications it may be necessary to select appropriate stress and the strain components at the integration points for stable and converging element behavior. Numerical examples illustrate various characteristics of the element.     

一种基于事件本体的文本事件要素提取方法

在事件信息的抽取中,事件要素的提取是一个难点。现有的事件要素抽取主要是基于机器学习的方法,这类方法容易受到语料稀疏性的影响。该文提出一种基于事件本体的事件要素提取方法,该方法将事件要素推理分为两步: 一、通过事件要素词和事件指示词的位置关系来初步填充要素值,并将得出的置信度较高的事件作为种子事件;二、利用第一步得出的种子事件,查询事件本体中的事件类约束和基于事件非分类关系的推理规则,并对要素进行推理,进一步对事件要素进行填充和修正。实验结果表明,该方法能较好地提升事件要素提取的准确度。     

A family of quadrilateral Mindlin plate elements with substitute shear strain fields

It is shown that selectively integrated Mindlin plate elements may be viewed as fully integrated elements with substitute shear strain fields. The defects of these elements are briefly reviewed and the 4-node element introduced by Bathe and Dvorkin is then generalised into a family of elements which is then studied. A set of examples is presented to illustrate the general behaviour of the family of elements.     

论酒包装设计中的“书画同源”

酒包装设计元素包括文字元素和图形元素,而文字设计元素需要表现的不仅仅是单纯的文字语意,还包括图形语言。文章说明了酒包装设计中的几种重要元素为商标、色彩、图形、文字,并指出了各自的地位和他们之间的关系,分析了中国酒包装设计中对文字的综合设计是如何来运用"书画同源"的设计方法的,最后运用成功案例进行分析,为中国的酒包装设计融入传统文化元素提供了一个参考。     

大气介质环境后向散射穆勒矩阵的特性分析

后向散射穆勒矩阵仿真应用的研究具有很多潜在的优势,通过分析穆勒矩阵元素传递的信息可以有效辨别介质特性.以大气环境介质为探究背景,通过偏振蒙特-卡洛仿真方法建模,分析了不同大气环境介质情形下,穆勒矩阵元素的变化规律.仿真结果表明:随介质粒子尺寸增加,穆勒矩阵元素整体呈现向中心收缩态势,特定元素对粒子尺寸敏感,其径向峰值可以明显反映粒子尺寸变化;随介质粒子浓度增加,穆勒矩阵元素强度衰减,特定元素圆周曲线幅值可以反映粒子浓度变化.     

基于多尺度轮廓结构元素的多形状边缘检测

在图像边缘检测过程中,针对滤除噪声及有效保留图像边缘信息这对矛盾点进行了研究,给出一种基于多尺度轮廓结构元素的多形状边缘检测算法。该算法通过多次使用轮廓结构元素的开最大和闭最小运算操作滤除噪声,运算次数通过比较图像峰值信噪比确定,降低结构元素对边缘信息的影响;然后采用多形状多尺度结构元素提取图像边缘,并利用图像峰值信噪比控制结构元素尺度的选取。与经典边缘检测算法相比,该算法具有更强的去噪声能力,且能保留更多的图像细节。仿真实验表明,有区别地使用轮廓结构元素及多形状多尺度结构元素,能有效去噪并保留边缘信息。