十面体

The variable geometry truss mechanisms have been studied extensively and systematically by this project. The research plan has been completed all sidedly, and expected results have been obtained. Three new kinds of combination decahedrons and a new class of variable geometry truss mechanism, which is composed of an octahedron and three tetrahedrons connected in parallel form, are proposed. The position analyses for decahedrons, dodecahedrons, triple-octahedrons, combinations decahedron and a new type of structure of variable geometry truss mechanisms are presented by introducing additional extra linear displacement sensors and using resultant elimination and homotopy continuation algorithms. The method of kinematical analysis of variable geometry truss mechanisms is established.

课题组对变几何桁架机构进行了深入的研究，全面地完成了研究计划，取得了预期的成果；提出了三种新的十面体组合机构以及由一个八面体和三个四面体组成的新型变几何桁架机构的结构形式；应用结式消元、附加传感器和同伦方法等提出了十面体、十二面体、三重八面体、组合十面体和新型变几何桁架机构的位置分析方法；建立了变几何桁架机构运动分析的一般方法；建立了简洁的凯恩和拉格伦日动力学的模型；应用有限元和子结构方法，提出了变几何柞架机构弹性动力学模型，导出了逆动力学方程的显式形式；设计和研制了一台可折叠的八面体变几何杵架机构装置等。

The morphologies of diamond include cube, cuboid, octahedron, cuboctahedron, twinned cuboctahedron, decahedron and icosahedron and ball-like diamond using SEM observation. The formation condition of the grains is discussed.

用SEM观察CVD金刚石晶粒形态主要有立方体、长方体、八面体、立方八面体、李晶八面体、十面体和二十面体颗粒以及球形金刚石，讨论了晶粒的形成条件。

The several shapes of diamond grains have been observed in SEM: truncated cube, octahedron, truncated cubo-octahedron, twinned cubo-octahedron, twinned regular decahedron and twinned regular icosahedron. Most of diamond grains are octahedron.

用扫描电子显微镜观察到多种外形的金刚石颗粒：截顶立方体、未截顶正八面体、截顶立方八面体、孪晶立方八面体、正十面体和正二十面体的金刚石颗粒。

Our results show that the duality of self-dual tetrahedral link is "trivial", and the duality of hexahedral and octahedral link as well as dodecahedral and icosahedral link are "nontrivial".

从构型角度考虑，四面体链环的自对偶是"平凡"的，六面体链环和八面体链环，十二面体和二十面体链环的对偶是"非平凡"的。

Goldberg got a class of polyhedra which are icosahedral symmetry by appending hexagons on regular dodecahedron by rule in 1937. They are called Goldberg polyhedra which provides a new approach for polyhedral molecule design.

1937年，数学家Goldberg通过在正十二面体上有规律地添加六边形面得到一类具有二十面体对称性的多面体，即Goldberg多面体。

It appears as a single-shelled icosahedron with 112 characteristic two-layer spikes.

该病毒仅有单层衣壳，病毒离子呈二十面体对称，二十面体的十二个顶点均有双层突起。

Similar conclusion will be right for other multiply twinned clusters, such asdecahedra, truncated decahedra and Marks decahedra.

同样的结论还可以应用到其它的具有多重孪晶结构团簇中去，如：十面体，截边的十面体和Marks十面体。

In contrast to ordinary liquid and amorphous alloys, the number of 1551 bonds related to the icosahedral structure becomes very smaller with the decrease of temperature,but the numbers of 1311,1301,1201 bonds related to the rhombohedral structure are increased remarkably.

结果表明，与通常液态及非晶态金属相反，随着温度降低，与二十面体相关的1551键型数越来越少，而与菱面体相关的1311，1301和1201键型数目显著增加，最后形成以菱面体结构单元为主的非晶态结构。

A systematic analysis of the icosahedral hierarchic structure in the 3D icosahedral quasicrystal and its approximants have been made. There is an icosahedron at the center surrounded by 12 icosahedra. If two neighboring icosahedra are vertex-sharing, the multi-shell Mackay cluster consisting of 127 atoms will form. If two neighboring icosahedra penetrate into each other, the multi-shell Samson-Bergman-Pauling cluster consisting of 137 atoms will form.

系统地分析了三维二十面体准晶的近似晶体相中具有二十面体对称的等级结构，中心1个二十面体，周边12个二十面体，如两个相邻二十面体共顶点连接，得出的是由127个原子构成的Mackay球形原子簇；如两个二十面体互相穿插，得出的是由137个原子构成的Samson-Bergman-Pauling球形原子簇。

Our results show that the duality of self-dual tetrahedral link is "trivial", and the duality of hexahedral and octahedral link as well as dodecahedral and icosahedral link are "nontrivial".

从构型角度考虑，四面体链环的自对偶是&平凡&的，六面体链环和八面体链环，十二面体和二十面体链环的对偶是&非平凡&的。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。