曲线拟合

A new curvature-based algorithm in free-form curve fitting was proposed to fit a 2D NURBS profile with an arc spline ,where a new form of curvature formula with matrix representation was also proposed,and then the arc spline tool path with G~(1) continuity was generated.

给出了一种平面曲线轮廓的圆弧样条拟合及刀具路径生成算法，该算法面向零件轮廓的光顺性刀具路径生成，通过应用曲线的曲率关系，对以NURBS表示的被拟合自由曲线按参数递增的方向用G1连续的圆弧或直线段逐段拟合，并生成相应的圆弧样条刀具路径，从而实现零件曲线轮廓表面的光顺加工。

Leastsquare method and Lagrange's interpolation formula see their applicationsfor fitting fore-and-aft lines-whose aim is to calculate the intersection point ofequivalent inclined waterline-and differences. In order to replace theinconvenient alternate conduct of drawing and calculating, improvement hasbeen introduced into the paper which means all work can be done bycomputer. Capacity calculation cannot be done without boundary layer build-up. Fit every area curve and area moment curve is necessary because ofinterpolation.

在第二章中，给出了B样条函数的数学表达形式，推导了B样条曲线下所围面积、面积矩公式；讨论了最小二乘法和拉格朗日插值法的数学形式，并在拟合船体型线上给出首、尾轮廓线的具体实例，对比不同方法进行拟合的差异，其目的是为了求得与等体积倾斜水线的交点；而水线的确定改变了以往人工作图与计算交替进行的不足，尝试用计算机完全代替人工作图，以求有所改进；在舱容计算中，在至少包括舱室前、后壁的范围内拟合横剖面积、面积矩曲线，插值求得任一纵向位置处的剖面，以解决舱室边界条件。

Results There was a linear trend between logarithmic X and Y, the equation of logarithmic curve was able to be fitted, There was a linear trend between logarithmic Y and X, the equation of exponential curve was able to be fitted, There was a linear trend between logarithmic X and logarithmic Y, the equation of power curve can be fitted. There is a parabola pattern between X and Y, the equation of parabola was able to be fitted.

结果 X取自然对数与Y作散点图有直线趋势，拟合对数曲线方程；Y取自然对数与X作散点图有直线趋势，拟合指数曲线方程；X取自然对数与Y取自然对数作散点图有直线趋势，拟合幂函数曲线方程；原始数据X和Y成抛物线关系，拟合抛物线方程。

As the complete characteristic curves of reversible pump turbine are often used to calculate the instantaneous parameters, this paper studies the characteristic curve and the wicket closure and opening law in pumped storage plants.Chapter 1 presents the importance and the necessity of this study and reviews the previous related research on hydraulic transient process and valve regulation in pumped storage plants.Chapter 2 analyzes the six collected characteristic curves of reversible pumped turbine and studies their diversification from the point of view of specific speed. The six collected discharge and moment curves with maximum efficiency have been fitted to piecewise continuous curves. This curve-fitting procedure is listed.Chapter 3 takes Liyang Pumped storage plant as an example and analyzes the effect of different characteristic curves on regulation guarantee parameters and the variety of its trochoid during the same operation status.Chapter 4 takes three pumped storage plants with different heads as examples and studies the characteristic of coordinated closure with wicket gate and ball valve and its effect on dynamic pressure in the spiral case, inlet pressure in the draft tube and the rise of rotating speed.Chapter 5 summarizes this paper and point out what should be done in the future research.

由于在过渡过程分析计算中，需要频繁利用可逆式机组的全特性曲线推求机组的瞬时参数，所以本文就特性曲线及关闭规律问题进行了研究，其主要内容如下：第1章，指出本文研究的意义和目的，回顾前人对水力过渡过程、抽水蓄能电站及阀调节的研究成果，在此基础上提出本文的研究内容；第2章，针对收集到的六套特性曲线，从比转速的角度出发来研究可逆式机组特性曲线的变化规律；并对六套曲线的最高效率流量和力矩曲线进行分段拟合，得到各分段函数的具体形式，再通过举例说明最高效率曲线的拟合步骤；第3章，以溧阳抽水蓄能电站为实例，分析讨论不同比转速特性曲线对调保参数造成的影响及对于相同工况其轨迹线的变化；第4章，结合高、中、低三水头段抽水蓄能电站，在导叶直线关闭的基础上，研究导叶与球阀协联关闭规律的特点及对蜗壳动水压力、尾水管进口压力及转速上升造成的影响；第5章，总结全文，提出今后研究的重点和方向。

By using hyperbolas to fit axial curves, considering the maximal error of the fitting curves as the objective function, the optimal fitting hyperb...

通过双曲线来拟合齿向曲线，使拟合曲线的最大误差为目标函数，利用优化的方法，使最大误差最小，得到最优的拟合双曲线，从而加工出所需要的齿形。

By using hyperbolas to fit axial curves, considering the maximal error of the fitting curves as the objective function, the optimal fitting hyperbola is obtained and the maximal error of fitting curves is minimal after optimization.

通过双曲线来拟合齿向曲线，使拟合曲线的最大误差为目标函数，利用优化的方法，使最大误差最小，得到最优的拟合双曲线，从而加工出所需要的齿形。

In order to contribute to analyse and compute easily setback moving devices on the projectile fuzes,and to make the fuze devisers be able to get the approximate acceleration curves with a few parameters such as tube length and muzzle velocity of the guns,the displacement-time curve and velocity-time curve of gun interior ballistic are fitted with the Logistic models,then the formula of projectile acceleration curves in bore are gotten by the derivation of the formula of fitting velocity-time curve.

为了便于炮弹引信后坐运动机构的分析和计算，能使引信工作者只根据身管长度和炮口速度等少量参数就能获得弹丸膛内加速度近似曲线，运用Logistic函数拟合火炮内弹道的位移－时间曲线和速度－时间曲线，再对拟合得到的速度－时间曲线求导便得到了弹丸膛内加速度近似曲线。

Study on method of curve simulation based on BP network .

基于BP网络曲线拟合方法的研究。

On the base of the data measured on automotive mechanics parameters tester, through setting up a relationship between lateral angle of tire, body roll angle, aligning torque and lateral acceleration and using method of least square, for curve fitting on non-linear data, a relationship has been found between these data and stable steering characteristics.

本文以汽车力学参数试验台测出的数据为基础，通过建立轮胎侧偏角、车厢侧倾角、回正力矩与侧向加速度之间的关系，运用最小二乘法对测试数据进行非线性曲线拟合，找出了这些数据与汽车稳态转向特性之间的关系，并按国家标准GB/T13047-91中的有关规定对被测试车辆的稳态转向特性进行了评价

It is found that Lorentz distribution is in reasonably good agreement with the employed experimental data.

另外，通过对试验数据的曲线拟合分析表明，Lorentz分布能很好地描述相应的试验数据。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。