二次曲面

Firstly part of quadratic term of Taylor series is chosen; a low-dimension surface is used to approximate limit state surface ; and the modified reliability formula is derived.

首次选取泰勒级数的部分二次项，用一个距原点最近点处拟合的超低维曲面近似极限状态面。

Firstly, the method fits each vertex and its local neighborhood of the clothing and human models by constructing the biquadratic Bezier surface. It can estimate the Gaussian curvature and the mean curvature of each vertex. Then, the feature points of two mesh models are extracted according to curvatures.

该方法基于双二次Bezier曲面局部拟合服装模型和人体模型的网格顶点及其邻近点，估算出人体和服装模型网格顶点的高斯曲率和平均曲率，然后提取出人体和服装模型两点集的特征匹配点。

Furthermore,we present the method for designing quadratic Bezier developable surface:give four corner points of developable surface and two free designing parameters,the other two control vertexes are on the line connecting the linear interpolation point between the first two control vertexes and the linear interpolation point between the last two control vertexes,and they are the linear interpolation points between these two linear interpolation points respectively,namely,these four linear interpolation points are colinear.

提出了二次Bézier可展曲面的设计方法：给定可展曲面的4个角点a0、b0、a2、b2和两个自由设计参数？姿、？滋，则待求的2个控制顶点a1、b1是在前2个控制顶点a0、b0的线性插值点a*与后2个控制顶点a2、b2的线性插值点b*的连线上，并且也是a*、b*这2个线性插值点的线性插值，即这4点a*、a1、b1、b*共线。

With the constraints of these feature points, perspective projection, coplanarity and colinearity, the curved surfaces can be recovered by minimizing the linearly constrained quadric objective function.

把特征点的位置、共面、共线、透视投影等作为约束，通过最小化线性约束下的二次目标函数实现曲面重建。

This paper proposes a robust filter function, called trilateral filter function, to filter the noises in the domains of surface curvature, normal and position at each sample point while the local surface is fitted in a quadratic form. By optimizing the filtering result of curvature tensor, our approach is capable of preserving the feature on the target model.

通过在扫描模型每个采样点处拟合一个二次型曲面，设计了一个鲁棒的滤波函数--三边滤波函数；应用该函数分别对模型表面上每个点的法线、曲率和位置进行滤波；通过对曲率的滤波结果进行优化，可有效地保持三维模型表面上的特征。

Aimed at the characteristic of multiple types of faults possibly happened in nuclear power plant, large scale of training sample, and requirement of quick and accurate diagnosing, after the analysis of large sample number generated by large fault type exceeds limitation of 64K paragraph in DOS and large number of local minmum in error surface, measurements of same format of data file, Win95/NT operating system platform, resetting weight learning rate, dynamic training set in quick learning algorithm and improvement on quick learning algorithm using homotopy method which can avoid local minmum points in error surface have been adopted to ensure quickly and effective process of the course of neural network's training and testing.

针对核动力装置可能发生的故障种类多，训练样本规模大，故障诊断需要快速准确的特点等，分析了样本多和故障种类多产生的训练样本量超出DOS段大小和网络误差曲面上局部极小值多的情况，采取了使用相同格式数据文件、Win95/NT操作系统平台，对快速学习算法采用重置神经网络权值学习率和动态训练集、并采用能够有效克服网络误差曲面上局部极小点的同伦方法对学习算法进行改进等措施保证神经网络训练测试过程的快速、有效地进行；针对装置发生的故障须快速、准确诊断的需要，分析了故障的产生对装置参数变化的影响及操纵员对故障诊断的基础，在核动力装置发生故障时参数曲线的变化量与正常运行时参数曲线的变化量存在明显差异的基础上，提出采用参数曲线的变化量作为神经网络的输入，并围绕参数变化量的方法采用二次曲线拟合滤波求变化量和阈值技术来保证神经网络得到精确的装置参数变化量，从而得到准确的诊断结果。

The quadratic patches is fixed,and its parametric representation method is gained.The cubic patches reduce to three local factors through reducing Bernstein coefficients to control shape of curve,two of them are used to join segments into G2- continuity approximating curves for given sequence data in space,and the other is used to adjust shape of segment.

先固定二次曲面片，并得到其参数形式，然后约简三次曲面片所对应的Bernstein系数，使之为带有三个形状调整的形状因子，其中两个分别代表曲线段端点处的曲率，另外一个作为形状的调整。

It can be indicated by the practical example that the fractal-interpolated surface function is obviously superior to the quadric polynomial surface for the fitted accuracy of the height anomaly.

实例计算结果表明，分形插值曲面函数拟合高程异常的精度明显优于二次多项式曲面。

He correspondence between two point set surfaces was established based on the deformation gradient and the moving least square method. The deformation gradient was decomposed into a rotation and a stretching component with the matrix polar factorization. Then each component was interpolated in dividually over the time. Shape interpolation was implemented through a global quadric energy optimization.

基于该变形梯度以及移动最小二乘方法建立了源点云与目标点云之间的对应关系；将变形梯度进行矩阵极分解，对分解后的各分量分别进行插值，再通过一个全局的二次能量优化实现点云曲面的形状插值。

Using application development tool Pro/Toolkit provided by Pro/Engineer and VC++, a surfrace-milling NC programming organ is created in this paper. It provides an interface with Windows style. It can obtain point cloud datum from the surface rebuild module expediently, and rebuild CAD modle with the data. Besides, it can input technical parameters from the human-computer interaction or the technical database. The data can be adjusted if it not suitable.

利用Pro/E的二次开发工具Pro/ToolKit和VC++创建曲面铣削数控程序生成器，并提供一个Windows风格的人机交互界面，能从曲面拟合模块方便地获取点云数据，并进行CAD造型，采用人机交互中或者从工艺信息数据库中传入相关加工工艺参数，如果对参数不满意，还可以进行修改。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。