截面曲率

The relations among three parallel sections,such as parallel mean curvature vector fields, parallel isoperimetric section and parallel umblic section,on submanifolds in the constantly curved Riemannian manifolds R ~ are studied.

讨论常曲率空间Rn+p中子流形上三类平行截面：平行平均曲率向量场、平行等参截面、平行脐截面三者之间的相互关系。

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。

Given a hyperbolic plane H2(-1)=,whose sectional curvature k is function K is the Gaussian curvature of the conformal metric g = e2ug ,then K satisfies the conformal Gauss curvature equation .

设H~2(-1)=是具常截面曲率k==1的双曲平面，其中B={∈R~2：x~2+y~2＜1}是单位圆盘，g=4(dx~2+dy~2)/(1-x~2-y~2)~2是所谓的Poincaré度量。考虑H~2(-1)上的共形形变度量？

Theorem 2 Let M~n be a compact totally real minimal submanifold in M~n which is a locally symmetric Bochner-Kaehler manifold.If the infimum of sectional curvature R_c in M~n satisfies: then M~n must be totally geodesic in M~n.

定理2 M~n是局部对称Bochner-Kaehler流形M~n中紧致全实极小子流形，如果M~n截面曲率下确界R_c满足：则M~n必是全测地的。

Combining with the National Natural Science Foundation ofChina(No.50478032), following researches were done in this thesis: 1 The variation regularity of the ultimate anti-bending capacity of therectangular-sectioned beam with different corrosion has been obtained through thequalitative analysis of 48 beams (32 corroded beams and 12 comparing beams) withaccelerated corrosion; 2 The conclusion has been obtained that the strain of corroded steel bar andconcrete no longer fit in with the assumption of plane section through the analysis ofthe strain data, the strain relation of steel bar and concrete in the mid-span section ofvariously corroded beams at ultimate has been obtained. Through the building of newgeometric relation, the expression of the height of compressive area in the corrodedbeam with rectangular section has been deduced, and the formula with corrosion rateas the main variable for the anti-bending capacity of the corroded concrete beam hasbeen suggested and verified by experiment.; 3 The influence of steel bar corrosion and the concrete regression to the flexureductility coefficient of the corroded structure component has been analyzed. Based onthe relation of steel bar and concrete at yield and ultimate, the expression for theflexure at yield and ultimate of corroded reinforced concrete beam, and the model forthe calculation of the flexure ductility has been built.

本文结合国家自然科学基金项目(50478032)"既有钢筋混凝土桥梁时变可靠度研究"，主要进行了以下研究工作： 1通过对48根快速锈蚀钢筋混凝土矩形截面梁(32根锈蚀梁和12根对比试验梁)数据的定性分析，得到了不同锈蚀率下，锈蚀钢筋混凝土矩形截面梁极限抗弯承载力的变化规律； 2通过对应变数据的分析，论证了锈蚀构件钢筋和混凝土的应变不再符合平截面假定的结论，并通过回归分析得出了不同锈蚀率的螺纹钢筋梁和光圆钢筋梁在极限弯矩作用下，跨中截面处钢筋应变和钢筋处混凝土应变的关系，通过构造新的几何关系，得出了锈蚀钢筋混凝土矩形截面梁计算受压区高度的表达式，既而得出了以锈蚀率为主要变量的锈蚀钢筋混凝土矩形截面梁的正截面抗弯计算建议公式，并通过试验数据加以验证； 3分析了钢筋锈蚀和混凝土劣化对锈蚀构件曲率延性系数的影响，结合钢筋屈服和极限弯矩两种状态下钢筋和混凝土的应变关系，分别得到了锈蚀钢筋混凝土矩形截面梁屈服曲率和极限曲率的计算表达式；既而推导出曲率延性系数的计算模型。

In chapter 4 and chapter 5 we focus on spheres with positive sectional curvatures.

在第四章和第五章中我们重点考虑正截面曲率的球面。

Experimental Research on FBG Sensor for Large Curvature Detection;2. For large curvature arch, the neutral axis does not pass through the centroidal line of the cross-section, so the moment of inertia is not consistent with the second moment of area.

大曲率拱中，截面形心轴与中性轴不重合，其截面抗弯惯性矩与不考虑曲率影响的截面面积二阶矩有一定的差别；当截面尺寸相对拱弧长来说较大时，此时拱为深拱，剪切变形的影响不能忽略。

A computing method is presented for studying the bending moment, axial force and curvity relationship at the section of prestressed concrete beam.

提出预应力砼截面弯矩－轴力－曲率关系的计算方法，并计算了不同预应力度下截面的弯矩－曲率关系。

The experimental data has proved that the method can be fit for the shaft with small curvity , especially in straightening the axis in auto′s gearbox.

提出预应力砼截面弯矩－轴力－曲率关系的计算方法，并计算了不同预应力度下截面的弯矩－曲率关系。

In this program, the declining segment of the stress-strain relation of the concrete, the restriction effect of hooped reinforcement and the bond-slip problem of the reinforcement are considered, as the same time the optimized arithmetic is applied to accelerate calculation procedure. Though the appropriate experiment arrangement, the influential factor such as the strength of concrete, the ratio of hooped reinforcement, the ratio of axial compression and the loading angle are researched, some available rules of carrying ability and ductility of the special-shaped column can be attained.

程序中考虑了混凝土应力应变曲线的下降段及箍筋对混凝土的约束影响，采用了合适的算法加速计算过程并考虑了纵筋锚固滑移的影响，通过正交试验分析了混凝土强度、体积配箍率、轴压比和荷载角对异形柱截面抗弯承载能力及截面曲率延性比的影响。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。