无根树

航天器多体系统是机械多体系统的一个重要分支，太空站、空间机器人、带太阳帆板展开机构的卫星等航天器多体系统都属于无根树多体系统。

Spacecraft multibody system is an important branch of mechanical multibody system . Space Station , space robot , satellite with solar panels are all the rootless tree multibody system .

运用EM算法构造并证明Jukes-Cantor模型下含缺损数据的DNA序列构建有根树（无根树）的最佳分枝长度估计定理；

To construct and to prove , using EM algorithm , the theorems of estimating best branches of DNA sequences having censored data for Jukes-Cantor Model under the conditions of rooted tree and un rooted tree respectively ;

对于铰联结系泊多浮体系统，将其作为铰联结无根树系统，用多刚体力学Huston方法进行了运动学分析。

The Huston method , a rigid multi body kinematic analysis method , is used to analyse the hinged multi body floating system which is treated as hinged rootless system here .

腾空阶段把袋鼠抽象为无根树型四刚体系统。

In flight phase , a non-tree type four rigid body systems is based .

该系统采用无根分枝树型以太网结构，符合基于C/S网络模式的各工序物料管理、物料消耗管理要求，同时也符合当前网络技术发展趋势，具有较高的性价比。

This system is based Ethernet structure which has not the root , and based on B / S network mode , according with the management and consumption of every working procedure and the development trend of present network technology , and it have higher cost performance .