结构单元

In this paper, based on the idea of knowledge constructionism, a structural knowledge representation approach is proposed. The "Unit" is defined as the essential knowledge component, and ten types of units and relations between units are suggested.

本文以认知科学中的知识建构理论为基础提出了一种结构化知识表示方法，此方法以"单元"作为知识表示的基本结构模块，将单元划分为十种类型，并定义了单元之间的关系。

Using the Mindlin theory, the four-node finite element shell modal of healthy and damaged structure is formed; Using Green Function theory, the fluid around the structure is considered to be inviscid, irrotational and incompressible, and then the effect of fluid to structure is translated to the added mass matrix compared with global mass matrix using BEM.

基于Mindlin理论，本文建立了描述健康和损伤的四结点有限元板壳单元模型；基于Green函数理论，将结构所处的流体环境考虑为无粘、无旋、不可压缩的理想流体，推导了三维问题拉普拉斯方程的基本解，并利用边界元方法将流体对结构的影响归结为对结构整体质量矩阵的影响；针对各向同性损伤单元，采取刚度各向整体弱化的方法分析；对于各向异性损伤单元，采用Kachanov理论，引入了x和y两个方向的弹性损伤折减系数。

Results show that the G and S units of wheat original lignin consist of 25. 35mol% uncondensed G units, 17. 60mol% uncondensed S units and 37. 05mol% condensed G units. The dissolution rate of S units is faster than that of G units in SFP—AQ and AP—AQ cooking. The residual lignin in SFP pulp has smaller amount of DPM structure and thus has better bleachability compared with those in AP pulp.

研究结果表明麦草原本木素G和S单元由25.35mol％的非缩聚G单元，17.60mol％非缩聚S单元和57.05mol％的缩聚G单元组成；在SFP—AQ和AP—AQ蒸煮中，木素S单元的溶出速率大于G单元的溶出速率；与AP浆比较，SFP浆中残余木素含有较少的DPM结构，从而具有较好的可漂性能。

First, the cross section of a boxlike girder is discretized into stiffened elements and corner elements, then the FEM program is compiled to calculate the curve between stress and strain of every stiffened element.

加筋板单元是船舶与海洋工程等箱型梁结构的主要组成构件，首先将箱型梁剖面离散成若干加筋板单元和角单元，利用非线性有限元方法逐一计算加筋板单元的应力—应变关系曲线，然后再用逐步破坏分析法得到整个结构的弯矩—曲率曲线，从而求得其极限弯矩。

As finished restructure power unit , would not change bulk and build technique, so framework and bracket of power unit not need restructure, at on time it not change intricate rigid connect frame of main loop in power unit , only change crustaceous configuration have already preconcerted objective.

功率单元结构更改后，其大小和安装方式未变，所以变频器的功率柜内的结构体与功率单元托架无需改变，同时功率单元内部的主回路的复杂刚性电气连接件均未改变，只是对外壳结构体进行改动就完成了预定的目标。

Cascade multilevel converter is made up of modules. It can be normally divided into two kinds: one with same modules and the other with different modules. This paper analyzes the relationship among the maximum number of output voltage level, the number of cascaded modules, and the input voltage ratio and THD of output voltage in different kinds of cascade multilevel converter. Then, some guidelines for making up cascade multilevel converter are given.

级联型多电平变换器类似于积木化的结构，本文按模块单元的结构形式，将级联型多电平变换器分为相同单元和不同单元两类，以输出最大电平数为目标，系统地分析模块单元个数与最大输出电平数、输入直流电压与最大输出电平数、以及输出电平数与谐波畸变率之间的关系，从中归纳得到构造级联型多电平变换器的指导原则。

In order to improve the efficiency, an implementing scheme (according to the distribution of strain energy density) was suggested when to consider the fact that the high gradient usually appears only in a very local region, especially in the case of huge amount of computation. All programming has been finished on the platform of commercial codes Mathmatica and Fortran.4. A number of numerical examples and applications were presented to verify the proposed Bezier-Based Element Method. The engineering cases include: the belt die for diamond synthesize, the main frame of wire-rounded press, the hydraulic cylinder of open die forging press. The numerical results show that the BBEM has some good performances.

通过大量的数值算例来考证所构建的各种类型单元，并应用于人造金刚石年轮模具、钢丝缠绕预应力机架和液压机工作缸等实际问题的结构分析；结果表明：所构建的Bezier耦合单元具有描述较大梯度变化场(如位移场、应力应变场等)的能力，该方法不改变单元的大小和形状，保持单元的自由度数不变，而通过调节中间可动节点的位置改变单元内部的场分布，只需少量单元即可较精确地模拟较大的梯度变化；可为有效求解高梯度问题提供新思路，对实际工程应用具有重要意义。

A number of numerical examples and applications were presented to verify the proposed Bezier-Based Element Method. The engineering cases include: the belt die for diamond synthesize, the main frame of wire-rounded press, the oil cylinder of open die forging press. The numerical results show that the BBEM has some good performances. With few elements, the BBEM can lead to a high accuracy. If using same DOFs, the computing precision of BBEM is remarkable higher than that of the conventional FEM.

通过大量的数值算例来考证所构建的各种类型单元，并应用于人造金刚石年轮模具、钢丝缠绕预应力机架和液压机工作缸等实际问题的结构分析；结果表明：所构建的Bezier耦合单元具有描述较大梯度变化场（如位移场、应力应变场等）的能力，该方法不改变单元的大小和形状，保持单元的自由度数不变，而通过调节中间可动节点的位置改变单元内部的场分布，只需少量单元即可较精确地模拟较大的梯度变化；可为有效求解高梯度问题提供新思路，对实际工程应用具有重要意义。

The inner force of the line element for underground structure have been calculated using the traditional finite element mesh and high-order manifold method to guarantee the numerical precision of the line element and overcome the disadvantages due to the geometry error between the actual position and computational position of the beam and truss element in common use.

用传统的有限元网格和流形方法的高阶覆盖位移函数来进行地下结构的杆、梁单元计算，保证了线单元模拟的数值精度，同时又克服了常用的杆、梁线单元计算位置与实际位置不相符合从而带来计算误差和结构设计不便等缺点，提供了一种解决结构数值计算的较好的途径。

Aiming at the guided entity model of apiece component, some frame boards of skin, ventro-board and crossbeam is simulated with curve surface, strengthen rib, frame and bars are simulated with curves in this paper, predigesting entity models to geometry models.

在ANSYS中，选取体单元solid45、壳单元shell63、梁单元beam188、质量单元mass21分别对相应的几何模型划分网格，用耦合方程实现23-3航炮所简化的质量元同炮舱结构其它组件的连接，建立了炮舱结构的有限元模型。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。