双纽线

研究得出它具有三种基本形式：①当时，为不共焦点的Booth双纽线族；

The three basic forms of the curve are as follows : ① when , the horizontal projection curve of the intersection curve is the Booth lemniscate family which isn 't confocal .

柏努利方程演示实验装置的改造和使用③当时，为其特殊情况伯努利双纽线。

Reconstruction and Facture of the Demonstration Device for Bernoulli Equation ; ③ when , , the horizontal projection curve of the intersection curve is the special Bernoulli lemniscate .

证明中心对称三次系统的一类双纽线有界周期环域的poincare分支至少可以出现作对称（3,3）分布的六个极限环。

In this paper , we proved that the Poincare bifurcation of a class of double folium curve bounded periodic ring region in a central symmetry cubic system can appear at least six limit cycles which are formed by the central symmetry in ( 3,3 ) .

双纽线流量计的设计和校验

Design and Calibration of the Flow Meter with Double Folium Curve

并在参数平面上得到了具有双纽线解①时的一般三次系统所有可能的轨线的拓扑分类。

Further , we obtain the whole possible topological classification of the trajectories in the parameter plane of the general cubic system which possesses the double folium solution ① .

此外由于它们还具有三角函数的优点，故既可以精确表示直线段、二次多项式曲线段又可以精确表示圆弧、椭圆弧等二次曲线以及心脏线、双纽线等超越曲线。

They not only inherit the advantages of Bezier curves and B-spline curves , also can be used to represent straight lines precisely and some remarkable transcendental curves precisely , such as circular arc , ellipse , cardioids and twisted pair line etc.