几何截面

Convex body; star body; cross i-section; Firey projection; Radon transform; Fourier transform of distribution; generalized intersection body; dual mixed volume; embedding in L_p

基础科学，数学，几何、拓扑凸体；星体； i-维中心截面； Radon变换；分布的Fourier变换；广义截面体；对偶混合体积；等距嵌入L_p

At many occasions they arise quite natu-rally.For example,they appear in the Iwasawa decomposition of the isometry group ofa non-compact Riemannian symmetric space.Also,every connected homogeneous Rie-mannian manifold of non-positive sectional curvature can be represented as a connectedsolvable Lie group with a left-invariant Riemannian metric.

它们出现在非紧致黎曼对称空间的等距群的Iwasawa分解中；任一非正截面曲率的连通齐性和黎曼流形可以表为带有左不变黎曼度量的连通可解李群等，带有左不变黎曼度量的幂零及可解李群的微分几何，调和分析和谱几何是重要的研究课题。

This paper deduces the accurate formulas for calculating the geometric characteristics of effective cross sections of members with welded H-shaped cross sections in gabled frames,and in order to simplify the calculation,presents the corresponding approximate calculation formulas.

推导了门式刚架中焊接H形截面构件有效截面几何特性的精确计算公式，为简化计算过程，给出了相应的近似计算公式。

The relationship between the G(superscript *) integral of release rate of non-spontaneous extending energy and stress-intensity factors was given. The relationships among G(superscript *) integral, load, geometry parameters and machine function parameters were provided. Furthermore, the stress intensity factor of center cracks in sectional I beam was obtained.

给出了工字型截面梁裂纹非自发扩展能量释放率G积分与应力强度因子的关系，同时也给出了G积分与载荷、几何参量以及机械性能参数的关系，进而得到工字型截面梁腹板中心裂纹的应力强度因子。

The effects of different parameters and cross-sections on axial velocity, the distribution of secondary flow, temperature field, turbulent kinetic energy, wall friction coefficient and wall Nusselt number are analyzed in detail.

详细分析了充分发展的和发展段的湍流管道内，不同截面形状和几何参数对轴向速度分布，截面二次流结构，湍动能，曲线管道摩擦比，温度分布和曲线管道Nusselt系数比等管道流动和传热特性的影响。

The structural design is carries on the design calculation after the plan comparison and appraisal recommendation plan, this stage design primary mission is: The design material analysis and the structure arrangement, the king post endogenic force computation, the pre-stressed steel ties the estimate and the arrangement, the computation king post section geometry characteristic, the steel tie the loss of prestress computation, the king post section intensity checking calculation, the king post nose partial bearing strength checking calculation, the king post distortion checking calculation and part compositions and so on lane board computation.

结构设计是根据方案评比后的推荐方案进行设计计算，这一阶段的设计主要任务是：设计资料分析及构造布置、主梁内力计算、预应力钢束的估算及其布置、计算主梁截面几何特性、钢束预应力损失计算、主梁截面强度验算、主梁端部的局部承压强度验算、主梁变形验算和行车道板计算等部分组成。

And then the node coordinates of the sections of aircraft can be achieved according to the variable parameters which are to be optimized, the constant parameters and the planform of few control sections.

建立了类似F-22布局的飞机外形的几何模型生成方法，可以根据优化变量和固定参量的值，以及少数几个控制截面的形状，生成飞机外形各个截面的节点坐标。

The stealth warplane for the microwave radar usually have complicated structures with the coating of wave absorption. On the base of calculation and modeling of the geometrical structure of the warplane in real size, the HF RCS of the air crafts under two different polarizations in different direction have been calculated with the FDTD. The result shows that the above mentioned stealth warplane have the obvious characterstics of frequency resonance, polarization and the relatively large RCS in HF Band 10-30dBm2, which can be used as the theoretical reference for selection of working frequency for sky wave OTH Radar and it also means that the sky wave OTH radar has good capability of anti-stealth targets quantitatively.

对微波雷达具有隐身作用的飞机，其形体较为复杂且表面涂敷有强吸波材料在对一种具有隐身几何外形结构实际尺寸飞机进行计算建模的基础上，文中采用FDTD技术得到了两种极化状态下该飞机无涂敷时不同方向上的短波雷达截面RCS值其结果显示了这种隐身几何外形飞机在短波波段有明显的频率谐振特性、极化特性和较大的RCS10-30dBm2，可为天波超视距雷达在选择工作频率时提供理论参考，并定量地说明天波超视距雷达具有较优的反隐身目标能力

Through anaslysing section real constant and weight of different parts and selecting different element type which are based on structure blueprint, we will build the ANSYS model.2. Unloader boom will be discrete based on trolly travelling on it.

根据卸船机的金属结构设计图纸确定卸船机各个部件几何尺寸以及具体位置，通过分析不同部件的截面尺寸以及重量计算其相应的截面性质和材料密度，以及不同的结构部件采用其相应的单元类型，从而建立抓斗卸船机作业时的载荷变化与运行的在ANSYS中数学模型。

The paper reviews the development in the analytical theory of mechanical behavior of composites, pointing out the problems existed, presenting creatively the concept of yarn state, solving the descriptive problem of perform structure of any woven composites and laying the foundation for predetermining the elastic behavior of 3-d woven composites with computer. On the basis of yarn state, the relative cross section deformation theory is introduced, the yarn cross section deformation is studied, and the experiential formula is described in the paper on the basis of experiment. The crimping state of yarn is studied, the classical "straight warp view"is modified, and the crimp height value of crimped yarn is studied. At the same time, with shrinkage rate sine method, the paper proposes the idea which imitate the shape of crimped yarn. With the third power template curve, the paper describes the microgeometry structure of fabric, finding a brief and precise approach for the calculation of mechanical behavior of composites.

本文回顾了复合材料力学性能分析理论的发展，指出了存在的问题，创造性地提出了纱态概念，解决了任意结构机织复合材料预制件结构表征问题，进而为用计算机预报三维机织复合材料的弹性性能打下了基础；基于纱态概念，提出了相对截面变形理论，研究了纱线截面变形情况，在实验的基础上给出了纱线截变经验公式；研究了纱线屈曲状态，修正了传统的&地经纱直线论&，提出了以纱线缩率研究屈曲峰谷值的思想，同时以三次样条曲线拟合了纱线的卷曲形状，较好地描述了织物的细观几何结构，为复合材料力学性能的计算找到了一条既比较简便又比较精确的途径。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。