曲线拟合

An optical system with refraction and total internal reflection was proposed according to the luminous characteristic of LED and the law of energy conservation. The ordinary differential equations satisfying the spots on the contour curve of TIR refractive and reflective planes were established. The coordinates of points on profile curves were obtained by solving these ordinary differential equations using Runge-Kutta method. The profile curves were acquired by curve fitting of the coordinate spots with software UG, and then TIR model of the projector and data of the surface shape suitable for NC manufacture were obtained.

根据LED的发光特性以及能量守恒定律选择采用折射全反射光学系统，通过建立TIR折射面及全反射面轮廓曲线上的点所满足的常微分方程，利用RungeKutta求解常微分方程得到轮廓曲线上点的坐标，再在UG中对坐标点进行曲线拟合得到轮廓曲线，进而得到TIR模型及适合数控加工的面形数据。

Results of landslide displacement curve reveal that the shape of creep curve is very similar to that of part of normal distribution curve.

研究发现它与正态分布曲线非常相似，基于此，首次提出了用修复的正态分布曲线拟合蠕变曲线的方法和模型。

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。

When Logistic curve was used to coincide with the state distribution of the change of b...

用 Logistic曲线拟合毛竹笋含水率随干燥时间变化的状态分布，幂函数拟合制品复重率的状态分布，决定系数 r2 分别达 0 。972 5和 0 。961 0以上

The analytical method used in this paper is justified by comparing with country norm form formula results , the result of Franco et al and the result of Yuxiu Wei et al.

综合各因素的影响，应用最小二乘法进行曲线拟合，得到了斜向波和多向波作用于直立堤上的平均越浪量的计算公式、单波最大越浪量的计算公式、单波最大越浪量和平均越浪量的关系式、越波率计算公式以及单波越浪量的统计分布形式，并通过与按照我国规范中斜坡堤越浪量计算公式形式拟合得到的直立堤越浪量公式和俞聿修，魏德彬的试验结果、Franco C，Franco L试验结果的比较来验证本文所采用的分析方法的合理性、试验结果的可靠性，以便于理论研究和工程设计参考应用。

That the fitting residual errors are in the 1nm magnitude order,so the curve fitting algorithm can be used in the high-precision curve fitting exactly.

试验结果表明：该算法的拟合误差在1nm数量级，可用于完成高精度的数据曲线拟合。

Based on the example of turbine reverse engineering , the general procedure that can be used to translate the physical object into CAD datum by Surfacer software is determined in this paper1 By going deep into the vector of point-cloud , it's parametrization can be gained by adopting the precept of accumulating chordal parametrization1 According to the principle of const ructing curve using the least square method , the high quality-curve can be gained by modifying curve's parameter1 This paper also empha2sizes on some methods about processing point-cloud , const ructing curve and const ructing surface1 And it can provide several methods to const ruct high quality2CAD model for mould machining1

此栏目为免费论文，可自行复制获取，如需要其他完整论文，可点击论文范文查找摘要本文就涡轮反求造型的实例，采用Surfacer 软件规划出由实物转化为工程CAD 资料的一般流程。在深入分析点云数据的矢量方向基础上，采用积累弦长参数化方案实现点云的参数化；根据最小二乘法曲线拟合原理，修改曲线参数获得高品质曲线；并重点论述了点云处理、曲线生成、建构曲面的方法，为模具加工提供了建构高品质CAD 模型的有效途径。

In order to assurance the maching accuracy and surface quality of steam turbine blades,based on typical CAD/CAM software Pro/Engineer 2.0,the flow diagram of parametric modeling and maching of turbine blades is drawn;The 3-D entity model of Steam Turbine Blade is upbuilt by parametric modeling method,and the fit-method with NURBS is extracted to smooth the curve surface,and the matrix expression of NURBS is deduced to make the surface more accurate;Then based on it's CAD model,the maching technology process...

为保证汽轮机叶片的加工精度和表面质量，以典型的CAD/CAM软件Pro /Engineer Widefire2.0中文版为基础，绘制了汽轮机叶片参数化设计加工的流程图；用参数化建模方法建立了叶片的三维实体模型，提出用NURBS曲线拟合方法进行光顺处理，并推导出NURBS的矩阵表达式便于截面型线的拟合，进而使叶片的造型更加精确；在CAD模型的基础上，分析了叶片的加工工艺流程，并用软件的CAM功能对叶片进行数控加工仿真，生成了NC代码。

A curve-fitting method in HDT and VICAT softening point measurement and a method for on-line parameter modifying were proposed.

通过试验和分析提出了在热变形温度与维卡软化点测定仪中应用温度曲线拟合的测定方法，介绍了拟合方程系数的在线修正方法。

RCBV values calculated using cSVD and oSVD were identical. Both values were equal to the whole areas under the concentration-time curve were divided by the arterial input function areas. Moreover, these rCBV approximated to the rCBV calculated by signal-time curve fitting. rCBF with cSVD and oSVD wouldn't be underestimated by delay effect and were good for relative quantity. The scatter plots of rMTT and Td were useful in stroke staging.

cSVD和oSVD所得组织脉冲反应曲线的面积相等，均等於完整的浓度时间曲线下面积除以动脉输入函数下全部面积；而且，此结果和讯号时间曲线拟合很接近。cSVD和oSVD不会因延迟效应低估rCBF，可以良好反应不同组织的血流量相对值。rMTT和Td散布图在不同疾病种类或处於不同疾病分期，显示不一样的分布。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐