弧长

Eight pairs of twins were collected. Twin zygosity diagnosis were made by micrsatellite DNA polymorphism. The collected data included clinical oral examination and measurements of dental model. The heritability of tooth mesiodistal diameter, the length of dental arch and crowding factor were systematically analyzed.

以48对双生子作为研究对象，应用卵型鉴定技术分为单卵双生子组和二卵双生子组，采取牙牙合石膏模型并进行测量，获取牙齿近远中径大小、牙弓弧长及牙列拥挤度等数据；采用Holzinger经典双生子法计算遗传度。

It was found recently that magnetic arc blow, inherently happens with such kind of welding process, particularly in deep groove welding of the first layer, can produce various kinds of weld defects, interfere the welding operation and make the arc length control system to work unproperly.

近年来在MIG焊研究中发现电弧磁偏吹现象严重，特别是坡口对接封底焊，会造成多种焊缝缺陷，甚至无法进行焊接，还会造成弧长闭环控制系统混乱。

In the previous issue on the basis of the theory, structure based on the 8051 MCU EAF arc length waveform generator system, through a link on the waveform of the hardware and software to achieve a further wave of EAF the main circuit hardware simulation.

本课题在前人的理论基础上，构造了基于8051单片机的电弧炉弧长波形产生系统，通过对波形的发生环节的软硬件实现产生波形进而对电弧炉主电路的硬件进行仿真。

The heritability of maxillary arch length (71.26%) was higher than the mandibular one (31.33%). The intraclass correlation coefficients were similar in dental crowding between MZ and DZ, with the lower in DZ. Low heritability of dental crowding was found in both maxillary (4.73%) and mandibular (10.3%) teeth. Conclusion The maxillary teeth MD, the mandibular teeth MD and the length of maxillary dental arch are controlled under strong genetic factors.

上下颌牙量遗传度较高，上颌为69.97%，下颌为75.73%；上颌牙弓弧长的遗传度(71.26%)明显高于下颌(31.33%)；单卵双生子和二卵双生子上下颌牙齿的拥挤度的对内相关系数较为接近，二卵双生子略低，遗传度很低，上颌为4.73%，下颌为10.3%。

This algorithm provides a more continuous feed motion using C2 continuous derivatives and nearly-arc spline parameterization.

该算法采用二阶连续可导的五次样条和近弧长样条参数提高了进给运动的连续性；速度控制算法保证机床在高速运行过程中加加速度的二次连续、加速度、速度和位移与时间关系的高阶连续变化，并且保证在各自的约束范围内，从而使机床的运动平稳，避免产生大的冲击和振动，同时有利于提高加工质量，减少加工时间。

This paper presents a full digital control system for pulsed gas metal arc welding inverter.

设计并实现了脉冲焊电流和弧长的全数字控制，取得了良好的控制性能。

In the case of loadingalong curved strain path,the author discovered that the instability mentioned aboveoccured only if the curvature changed from large to small.The drop and recovery instress obviously depend on the curvature and its rate.

对曲线应变路径的情形，本文发现只有在曲率由大向小变化时才出现上述瞬时软化响应，且曲率改变变化趋势时曲率的大小及路径弧长对应力大小的降低和重新强化的程度及变化率的影响较为明显。

Finally, the experimental results show that the approximation methods are correctness and effective. As an application, generating quasi arc-length parameterization of PH curves is also discussed.

最后通过具体逼近实例验证了文中算法的正确性和有效性，同时给出了它在PH曲线准弧长参数化中的应用。

As an application,generating quasi arc-length parameterization of PH curves is also discussed.

在CAGD中，曲线曲面一般用多项式或有理多项式表示，因此求解多项式函数的反函数是CAGD中的一个基本问题，它在曲线的准弧长参数化、曲线隐式化、曲线求交等问题中都有非常重要的作用[1-2]。

Traditionally ellipsoids and hyperboloids are modeled as implicit surfaces or through the use of rational surface schemes. The existing methods for generating spheres or quadrics have shortcoming such as the rational parameterizations for these surfaces are non-uniform, the resulting scheme cannot represent these surfaces in their natural acr-length parameterization and the implementation of the scheme is complex.

长久以来，Subdivision方法对一些看似简单却又在计算机图形学中有着重要作用的曲线曲面的造型非常困难，即使是对简单的圆和球的生成也很困难，已有的一些生成球或二次曲面的Subdivision方法一般都有太复杂、不能自然弧长参数化或者计算量太大等缺点。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。