失稳

Based on analyzing and comparison of the several kings of theoretical formula and analyzing the composition and influence factor, this paper improves a common formula used in calculating jacking force in pipe jacking.

本文针对当前非开挖技术基础理论研究滞后于工程实践的现实，对顶管的推力理论、水平定向钻进的管道回拖力及其水平钻进过程中的孔壁失稳机理等问题进行了研究。

In this paper the problem of unstable character of forced-steering bogies with low wheel tread conicity is studied.

本文深入探讨了迫导向转向架所具有的低锥度失稳问题。

The results show that the increasing Marangoni number will lead to more nonlinear distribution of temperature field, but streamfunction of the cell center; vorticity on the wall and peak value of velocity diminish first, then increase, finally lose stability. The thermocapillary convection in the whole liquid zone appears to get stronger along with the augmentation of Prantal number. The effect of increasing of Biot number on temperature and flow fields is not obvious although the convection is strengthened a little. As increasing the aspect ratio A, thermocapillary convection induced by temperature gradient and liquid viscosity becomes stronger.

结果表明：温度场的非线性分布随着Ma数的增大而加剧，但对流涡胞中心流函数、壁面涡量和轴向、径向速度峰值并不象温度场随着Ma数的增大而单调增大，而是先减小，然后增大，最后失稳，表明Ma数对热毛细对流的影响比较复杂，针对不同的物理模型，会导致完全不同的流态；Pr数愈大，流体的热扩散能力在粘性扩散与热扩散能力之比中愈占支配地位，当Ma数一定时，热毛细对流随Pr数的增大在整个液体区域内有增强的趋势；Bi数增大，热毛细对流有所增强，但不甚明显；A的增大使得由温度梯度和流体粘性诱导的热毛细对流随之增强。

The instability originated in the upper R_B-like convection zone develops to larger region with the increase of Grashof number, and the number of non-axi-symmetric circulations decreases. When Grashof number exceeds another critical value, cooling air may invade the cavity and flow toward the shroud, the circulations decrease to one pair occupying the whole cavity in radial, thus these two zones are merged into one. The core structures in the cavity rotate against the disks, while the structures keep no change at the case of periodic oscillatory flow. With the Grashof number rises, the flow undergoes stable, periodic, periodic with cool air invading, quasi-periodic and ultimately to chaos.

离心浮升力是造成非等温轴向通流旋转盘腔内流动不稳定的主要因素，而哥氏力的存在加剧了流动不稳定性，导致流场失稳提前发生，而且在哥氏力的作用下流线发生偏转，盘腔内r-θ面出现了旋向相反的对涡，流动结构更加复杂化；随离心浮升力的继续增加，r-θ面的对涡减少，当其超过某一临界值后部分冷流体侵入盘腔，对涡减少至一对，而且沿径向充满整个盘腔；此后随离心浮升力的增加对涡的数量不再变化；r-θ面的对涡相对于盘面周向移动，但是形状基本保持不变。

The study reveals that the convolute bedding is genetically related to rapid deposition and wave-shaking.

通过研究发现，它们的成因与相对静水条件下快速沉积和波浪震荡引起沉积物泄水，形成密度倒置、重力失稳，最后导致发育底辟变形有关。

Criterion is proposed that the actual in-plane instability is determined by continuous expansion of plastic region of bellows and continuous deformation of corrugation.

提出了实际波纹管的平面失稳取决于波纹管塑性区域的持续扩展和波纹面的持续变形的判据。

The course emphasizes on the explanation about the basic principle of the twisting destabilization and the crankle destabilization.

在讲述各类构件及板件失稳原理的同时，分析各种构造措施和结构布置方案的合理性。

It provided a correct and reasonable mathematical model for the analysis of the ultimate bearing capacity and crankle stability of the thin-walled structure.

论文在比较了两种运动描述方法（完全拉格朗日法和更新拉格朗日法）异同点并分析了非线性几何关系及大变形下的弹性物理关系的基础上，基于增量虚功原理推导了几何非线性空间梁元单元切线刚度矩阵，采取分模块形式，分别表示了轴力、弯矩、双力矩对几何矩阵的贡献；通过球面显式荷载增量迭代式弧长法求解方法编制程序，很好地实现了几何非线性增量荷载的自动步长选择及全过程跟踪，为薄壁杆系结构的极限承载力分析和弯扭失稳分析，提供了较为精确合理的分析力学模型。

Our crippling dependence on foreign oil will continue.

我们的依赖外国石油的局部失稳破坏将会继续。

The change of contact area of earth caused by ground water is analysed, and the formula to calculate the critical angle of planar slide under the saturation condition is derived.

分析研究了地下水引起的接触面积的变化，并推导了饱水情况下平面滑动的临界角变化公式。λ越小，发生失稳破坏的临界角θ就越小。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。