四面体

Each atom behaves like a tiny bar magnet, and when the crystal is cooled to near absolute zero, the atom-magnets align.

有时候，四面体四个角中的三个排列在一起，使得四面体的中心产生磁单极子。

Nutlets 4, semiglobose-tetrahedral or subulate trigonous-tetrahedral, shiny, glabrous or pubescent, rarely tuberculate, adaxial 3 surfaces subequal in size or bottom smaller than 2 lateral surfaces, longitudinal vein at juncture of 2 lateral surfaces, sessile or with a short carpophore from corner of 3 adaxial surfaces, abaxial surfaces flattened or convex, acute or obtuse ribbed, rarely narrow winged; attachment scar at bottom of carpophore or at corner of 3 adaxial surfaces when sessile.

小坚果4，三棱四面体，发亮的半球形四面体或钻形，无毛或被短柔毛，具瘤，正面3 表面大小近等或者最后的小于2侧面的很少，在2侧面的接合的纵向脉，角落的3正面的在底部附件痕的果瓣柄或什么时候无梗。

The coordinate transformation and numerical integration was executed on the discretized tetrahedral elements based on which the 3-D MT vector-finite element method was implemented. A whole computation framework for 3-D vector-finite element method with unstructured mesh was given. Based on this some typical models were tested which has demonstrated that our algorithm could distinctively avoid problems caused by the fake solution and both the accuracy and efficiency were enhanced which made our algorithm has a bright future for further application.3. According to theory of Sobolev vector space and the discretization of Helmholtz space, the error estimate which was suitable for 3-D MT vector-finite element modeling was deduced by which the procedure of adaptive technique was guaranteed.4. Based on the fully unstructured tetrahedralization and optical strategy, the 3-D magnetotelluric h-adaptive vector-finite element method was presented through combining the error estimate. With this work, the accuracy and creditableness for 3-D MT complicatedly modeling was guaranteed.5. The 3-D magnetotelluric h-adaptive vector-finite element algorithm with unstructured mesh was implemented.

针对非结构化的四面体单元，采用坐标变换和数值积分方法，实现了MT三维矢量有限单元分析，建立起基于非结构化网格的三维MT矢量有限元计算流程，并对典型模型和国际标准电磁模型进行了数值模拟，结果对比和分析表明，基于非结构化网格的三维MT矢量有限元不仅消除了节点型有限元的伪解，而且具有很高的计算精度和速度，有广阔的应用前景。3、根据Sobolev函数的向量空间和Hemlholtz空间的分解，推导出基于残差的三维大地电磁矢量有限元后验误差估计公式，为三维大地电磁自适应矢量有限元数值模拟的实现奠定了基础。4、在完全非结构化四面体单元剖分及优化基础上，结合三维大地电磁矢量有限元后验误差估计公式，提出了基于非结构化网格的三维大地电磁h-型自适应矢量有限元计算策略，保证了对复杂大地电磁模型数值计算的精度和可靠性。5、实现了基于非结构化网格的三维大地电磁h-型自适应矢量有限元计算流程，对典型模型和国际标准电磁模型进行了数值模拟。

The results show that the particles character as the growth of anion coordination tetrahedron during solvent thermal treatment, where blende-type ZnS particle is in the shape of double cone or tetrahedron, blend-type CdS appears as the tetrahedron, but wurtzite-type CdS is in the shape of cone. In addition, the particles with the better crystallinity are obtained with the increase of solvent thermal treatment temperature and time.

结果表明：采用溶剂热处理，粉末形状呈现负离子配位多面体生长特征，闪锌矿型ZnS粉末由球形变为双锥状或四面体状，颗粒上有明显的电子衍射花纹；闪锌矿型CdS晶体粉末主要呈四面体形状，而纤锌矿型CdS晶体粉末则以锥状为主，并且粉末的晶型随溶剂热处理温度的升高和时间的延长更趋于完整。

We obtain three classes of polyhedra which have high symmetry. they are regular tetrahedral class belonging to tetrahedral group , regular hexahedral class and regular octahedral class belonging to octahedral group.

本文将Goldberg在正十二面体上构筑多面体的方法推广到其它柏拉图多面体上，分别得到了三类具有较高对称性的多面体：属于四面体群的正四面体类和属于八面体群的正六面体类、正八面体类。

As we all know,there is one Simson line at any point on the circumference of triangles,but in this paper, LHP theorem shows that the above conclusion is not correct for any quadrilateral pyramid in three-dimensional space and also during proving LHP theorem,fixed value theorem is proved,at the same time,one guess about the point H and point P on circumscribed sphere of tetrahedron has been concluded.

众所周知，三角形的外接圆周上任一点存在一条 simson 线，而 LHP 定理则指出对于正四面体该结论是不能推广到三维空间上的，并且在论证 LHP 定理的过程中得出了定值定理，同时作为一般四面体的外接球球面上的 H 点、P 点的分布，给出了一个猜想。

Fractal with OPENGL programming, you can see a rotation to regular tetrahedron, each tetrahedron is a fractal pattern interview.

详细说明：分形，用OPENGL编程，可以看到一个旋转地正四面体，正四面体的每一面试一个分形图案。

This structure took threefold-symmetric Bricard linkages,composed of six tetrahedrons,as fundament,and implemented retractability through tetrahedrons' rotation around the adjacent hinges.

这种结构以6个四面体构件形成的三向对称环形连杆机构为基础，通过四面体绕相邻铰转动实现结构的闭合和开启。

Particle system and Opengl mapping technology, according to the nature of being tetrahedron, a tetrahedral formation!

利用粒子系统和Opengl贴图技术，根据正四面体的性质，生成一个正四面体！

It was found that the inorphology ofsulfates is related to the orientation of tetrahedral [SO4]2- in the crystal, i.e., the faces, the edges and faees of the tetrahedra normal to, are expected to grow slowly and observed in final form; in contrast, the faces, the vextices of the tetrahedra pointing to, usually grow fast, and will disappear.

晶体的结晶形貌与[SO4]2-四面体在晶体中的结晶方位密切相关，四面体的面和棱的法线（ L 2）所对向的晶面，生长速率慢，顽强显露，均属晶体的板面；四面体的顶角所指向的晶面，生长速率快，显露面积小，经常消失。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了