极限

This paper presents the new bound theorems in structural limit analysis developed on the basis of the generalized variational principle. The approximate limit factors determined from the new bound theorems are closer to the exact limit factor than the ones obtained from the classical bound theorems.

本文给出在极限分析的一般变分原理[1]的基础上发展起来的极限乘子的新的上、下限定理[10]，由这个新的上、下限定理决定的极限乘子的上、下限比经典的上、下限定理给出的更为靠近准确解。

Recursion formulas for quantities at infinity in this system were presented.

同时，计算了一类三次系统的前6个赤道环量，得到了系统在赤道邻域的可积性条件及在赤道附近存在5个极限环的系数条件，给出了一个平面三次系统在赤道附近分支出5个极限环的计算实例，并在不构造Poincare环域的情况下，指出了极限环存在的位置。

At the same time, the ballistic limit curves of the Whipple shield in a velocity range from 0.5 km/s to 5.5 km/s was obtained. Comparing to the predicted curve from Christiansen ballistic limit equation, the experimental minimum critical projectile diameter is slightly greater than the prediction.

通过固定弹丸直径，改变弹丸撞击速度，寻找临界撞击速度的方法获得了铝合金Whipple防护结构在0.5～5.5 km/s撞击速度区间内的撞击极限曲线，并与由Christiansen撞击极限方程得到的撞击极限曲线进行了比较，结果表明，实验最小临界弹丸直径略大于预测值。

By getting Lebesgue characteristic of integrable function of Riemann from the definition of Gather zero measure, discussing the relation between almost continuous everywhere and existent of limit, it gets the theory which is from the function integrability to the consecution and from consecution to the limit existence .i.e. the almost limit existence is equal to the almost continuous everywhere in the integrable function of Riemann. It also gets a unified condition which has a wider range than regulated function and comes to the conclusion that the function of bounded variation is the integrable function of Riemann.

通过定义零测度集给出了可积函数的特征，讨论了其几乎处处连续与极限存在的关系，从而得到了从函数可积性到连续性，从连续性到极限存在性的函数特性理论，即可积函数中极限的几乎处处存在与几乎处处连续是等价的，得出比正规函数更加宽泛的统一条件，得出了有界变差函数是可积函数的结论。

The results show that under the same standard calefaction curve and the same load (132 74 kN), the fire endurance of naked WGJ510C2 is 39 min and that of Q235 steel is 27 min.

结果表明：在标准升温曲线和相同载荷(132 74 kN)下，裸露WGJ510C2 钢梁的耐火极限为39 min，裸露Q235钢梁的耐火极限为27 min，即裸露WGJ510C2钢梁的耐火极限比裸露Q235 钢梁高44 4%。

Recently, Professor Liu Wen and his associates study the strong law of large numbers for Markov chain fields on trees. But for the nonhomogeneous Markov chain fields ,they only study the even-odd Markov chain and non-symmetric Markov chain. However, this article goes in the normal nonhono-geneous Markov chain fields and gets a class of limit theorems for the functions of two variables of finite nonhomogeneous Markov chain fields. Some limit theorems on the frequences of states and ordered state couples are obtained by several corollaries.

最近刘文教授及其合作者对树上的马氏链场的极限定理作了研究，对于非齐次马氏链场，仅对其中的奇偶马氏链场和非对称马氏链场作了研究，本文讨论了一般的非齐次马氏链场的极限性质，得到了关于Caylay树上有限非齐次马氏链场二元泛函的一类极限定理，作为推论得到了关于状态与状态序偶出现频率的极限定理。

In this paper, several approximate methods are put forword to calculate the limited burring factor through analyzing stress and strain at the edge of the round-hole in the burring process.

这种极限变形程度可用极限翻边系数来描述，即在翻边过程中，翻边系数(K =d0 /Dm，式中d0 、Dm 分别为板料原始孔径和翻边后竖边中径图 1)，不能小于极限翻边系数。目前，在冲压理论中，有关极限翻边系数的理论探讨还很少[1，2 ，3] 。

The results of numerical analysis show that the elastic modular and the poisson ratio have no effect on two-dimensional bearing capacity, but can affect the ultimate bearing capacity of three-dimensional foundations and control the convergence and precision of finite element calculation; the earth pressure coefficient controls the geostatic stress of foundation, sequentially affects the ultimate bearing capacity of foundations and the convergence of numerical calculation. When calculating the ultimate bearing capacity of undrained saturated foundation, the complete formulation exists shear locking, and reduce formulation exists hourglassing, so the hybrid formulation is suitable to imitate the geomaterial. When the soil obeys nonrelevent flow rule, the yielding function is different from potential function, and the elastic-plastic matrix of soil is asymmetric, so the unsymmetry numerical solver and appropriate finite element mesh is required.

研究结果表明，土体弹性模量和泊松比对二维基础极限承载力没有影响，但是影响着三维矩形基础的极限承载力，控制着ABAQUS数值算法的计算精度与收敛速度；地基土压力系数控制着地基土体中的地应力平衡，从而影响着二维条形基础和三维矩形基础的极限承载力和地基破坏包络面；对于不排水饱和软黏土地基，常规的完全积分单元会造成剪力自锁现象，而减缩积分单元则存在过于柔化的现象，故采用杂交单元来模拟较合适；当土体服从非关联流动法则时，屈服函数与塑性势函数之间存在差异，从而导致土体弹塑性矩阵呈现非对称性，在有限元计算中必须采用非对称数值解法，并且合理地划分单元才能对极限承载力进行准确求解。

Because of its function in thought, limit appro...

由于极限具有这样的思维功能，通过学习极限、掌握极限法，就可获取数学思维方法，在用极限法解决问题的过程中不断提高自身综合能力。

The forming limit diagram relates to strain paths, then the forming limit diagram made in linear strain path can not be directly used to complex strain paths.

根据试验测定的不锈钢板材成形极限图用理论方法建立了不锈钢板材的成形极限应力图，其真实板材成形极限图和成形极限应力图均是一条直线，只有这样板材成形才能满足塑性变形体积不变条件。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。