方向极限

In such a medium, the direction of the Poynting vector monochromatic plane wave is antiparallel to that of its phase velocity. Because of that, DNG displays some unusual electromagnetic properties such as backward-wave effect, negative refractive effect, perfect lens and a limit situation, zero index of refraction materials.

在这种材料中，单色均匀平面波的相速方向和坡印亭矢量方向是相反的，因此使双负材料表现出一系列反常的电磁特性如：回波效应、负折射效应、完美透镜效应和一种极限情况即零折射率材料等。

Theoretical Part: Through theoretical analysis of chemothermodynamics, combustion and engineering thermodynamics, factors that affect explosion limit were determined, which include temperature, pressure, spark ignition energy, electrode shape, direction of flame propagation and size of explosion vessel.

理论部分：根据化学热力学、燃烧学和工程热力学的基础理论，从本质上定性地分析了爆炸极限的影响因素，包括温度、压力、爆炸容器的大小、点火能量大小、以及火焰传播方向等，得出了这些影响因素对爆炸极限的影响规律，以确保实验有完整的理论基础指导；在此基础上本文提出了一种新的推算在常温常压下可燃性纯质和混合工质制冷剂爆炸极限浓度的理论方法，该方法由可燃性气体的化学组成来推算上下限浓度，不需要其它条件；对混合工质制冷剂，只要再知道混合配比，即可以推算出爆炸极限，使预测爆炸极限的工作更简单、方便。

The problems of point - line - plane - volume; the facts of square - circle - triangle; the mysteries of central - peripheral - frontal - oblique - concave - convex; the right angle and perpendicular; of scale and position; the interest in post- lintel, wall-slab, vertical-horizontal; the arguments of two-dimensional and three-dimensional space; the extent of a limited field; the meaning of implied extension; the meaning of plan, of section, of spatial expansion - spatial contraction - spatial compression - spatial tension; the direction of regulating lines, of grids; the relationships of figure to ground, or number to proportion, of measurement to scale, of symmetry to asymmetry, of diamond to diagonal; the hidden forces, the ideas of configuration; the static, the dynamic: all these begin to take on the form of a vocabulary.

点-线-面-体的课题；正方形-圆形-三角形的事实；中央-边缘-正对-倾斜-凹入-凸出的奥秘；直角与垂直；尺度与位置；柱-梁、墙-板、竖直-水平的旨趣；两维与三维空间的思辩；局促场所的极限；暗示延伸的含意；平面、剖面、空间扩充-空间收缩-空间挤压-空间张拉的意义；控制线与网格的方向；图与底、数字与比例、尺寸与尺度、对称与非对称、菱形与对角线的关系；暗藏的力量、构型的想法；静态、动态━这一切都将发展成为语汇的形式。

This paper presents the concepts of double limit, repeated limit , directional limit and weak double limit of binary function, and discusses the relationships among them.

给出了二元函数的二重极限、累次极限、方向极限、弱二重极限的概念，讨论了这几种极限之间的关系。

An extremely high temperature of anode humidification is also unreasonable; as a result, when the current density is high, the liquid water should be injected directly into anode gas channel to guarantee both high inlet H〓 concentration and well-humidified membrane. 4. The utilization of Pt in the cathode catalyst layer will decrease with the increasing current density; as a result, based on the principle of maximal Pt utilization, the catalyst layer can be designed much thinner or not uniformly in the catalyst distribution.

而在此截面上，交指型流场燃料电池阳极侧的液态水饱和度的极值位置并不确定；在电池阴极处，液态水饱和度的极值总是出现在z=0.002m处的气体扩散层和膜的界面上，并且该处的液态水饱和度沿x方向存在一个最大值，与此相应的氧气的质量浓度分数在该处达到极小值，因此极限电流密度将首相出现该处，但总体来说液态水饱和度沿x方向的分布较为均匀。4。

When we analyse rigid body with the theory of limit equilibrium, we do not obtain always reasonable maximal principle in physics, and the maximal value is the result of soil plasticity deformation.(2) Thoroughly commenting the typical method of slices from their satisfid equilibrium conditions, calculational parameter and their convergence, the thesis sortes the methods into four kinds. The first satisfies all kinds of equilibrium conditions, can obtain interslice force and the factor of safety.

2从满足的平衡条件、求解的参数及其解收敛性等，分析了各种常用极限平衡条分法，将其分为四类，第一类方法既满足力的平衡，也满足力矩平衡，能获得条间力和稳定系数的收敛解；第二类方法只满足一个方向力的平衡和力矩平衡，只能求得稳定系数；第三类方法既满足力的平衡，也满足力矩平衡，但不是严格的静定问题，解的收敛性差；第四类方法满足两个方向力的平衡，不满足力矩平衡，可求得稳定系数和条间力的大小，不能求得条间力方向。

In each step the tangent plane of limit state surface at the previous iterative point is calculated firstly, and then a line from origin to a point on the plane is determined whose intersection with limit state surface satisfies the requirement of feasible direction and convergence.

算法在每步迭代中先计算极限状态曲面在前步迭代点处的切平面，然后在此切平面上选定一个点，使该点和原点的连线与极限状态曲面的交点满足可行方向和收敛的要求。

The method divides block along the intersection edge of joint faces and neglects the vertical shear force between dividing-blocks i.e. takes horizontal normal force and shear force into account; as to an assumed sliding direction, by satisfying vertical force equilibrium of every dividing-block and whole force equilibrium in the sliding direction, the factor of stability can be solved.

基于此，提出分块极限平衡分析法，该方法沿非临空面交棱将块体进行分块，在忽略分块间的垂向剪力（即可考虑分块间的水平法向力和剪切力）前提下，通过满足各分块的垂向力平衡和滑动方向上的总体力平衡，求解特定滑动方向的稳定系数。

The results show that the methane drainage quantity from the bores perpendicular to face cleat was 1.2 times that of the bores parallel to face cleat in any time and the difference between them becomes more distinct with the drainage time increasing. In the research area, the bores perpendicular to the face cleat was 2.61 times that of the bores parallel to face cleat in maximum drainage quantity and 4.34 times that in drainage effect, and the reasonable time is about 300 days.

结果表明：垂直面割理方向钻孔的抽放量在任何时刻都明显高於平行面割理方向钻孔的抽放量，抽放时间越长，两方向抽放量之间差距越显著；研究区垂直面割理方向钻孔的极限抽放量是平行面割理方向钻孔的2.61倍，抽放率高出4.34倍，合理抽放时间在300d左右。

There are two causes leading fractures of the endodontic instruments. Firstly as the value of the toque inc1ases beyond the limited toque, the instrument will twist with no increase in toque and will fracture soon. The value of limited toque is proportional to 3 squares of the file radius.

根管器械断裂的原因主要有2个：一是扭转超过极限扭距，器械顺着扭转的方向发生塑性扭转直至断裂，圆杆的极限扭距与其半径的3次方成正比；二是器械在循环载荷下发生疲劳损伤，最后突然断裂。

If you are unfortunate enough to the lovelorn, please tell me, I will help you out, really, please contact me!

如果你不幸失恋了，请告诉我，我会帮助你摆脱困境，真的，请联系我啦！

China's plan to cut energy intensity by 20 percent and pollutant discharges by 10 percent between 2006 and 2010 is a case in point.

中国计划在2006年到2010间降低20%的能源强度和减少10%的主要污染物排放，就是一个这样的例子。