次极限

The number and stability of the limit cycles of a class of polynomial system with degree n are studied under some conditions by means of the results about Abel equation.

并利用关于Abel方程的这些结果得到了一类n次多项式系统在一定条件下极限环的个数和稳定性。

The paper is devoted to the quartic invariant algebraic curves in quadratic system.

本文在给定参数满足一定的条件下，研究了一类二次系统的四次不变代数曲线系统平衡点的稳定性态，并运用Dulac函数法给出了该系统不存在极限环的充分条件，这一研究在同类问题中具有一定的拓展性。

Both single and double-stable limit cycle flutter states are found in wind-tunnel test. And the conclusion is proofed that the equivalent linearization based on the second order asymptotic solution of KBM method is more accurate than that based on the first order one, which is equivalent to the conventional harmonic balance method.

风洞实验时，吹出了单、双稳定极限环颤振情形，并验证了基于KBM二次渐近解的当量线化分析比KBM法一次渐近解的当量线化分析要精确一些的结论。

This paper is concerned with the analysis of cubic system's equivariant symmetric structure and the investigation of limit cycles bifurcation for several classes of equivariant cubic systems.

主要研究三次系统的等变对称结构以及不同结构的三次系统的极限环分枝行为。

We've been stretching our capacities to the limit, and we've been doing our damnedest, but America has still launched over 150 space missions and has watched three of them end in catastrophic failure.

我们拓展自身的能力达到极限，我们也尽了我们最大的努力，可是美国尽管进行了超过150次的太空任务，但要注意到其中有三次以惨痛的失败告终。

We give some equivalent characterizations of Bloch type functions in term of fractional derivative, via studying the relative of growth of the different order fractional derivatives of holomorphic function, including the form of supremum and limit, the form of integral and Carleson measure, which are the generalizations of some known results in the unit disc and in the unit ball.

我们从研究全纯函数分数次导数的增长性入手，利用分数次导数给出了它的一类刻画，包括上确界和极限形式的特征，积分形式的特征以及Carleson测度形式的特征，推广了单位圆盘和单位球上一些已有的结论。

Aim at the shortage of vertically additive method by which we can't discuss forced oscillations of systems of partial functional differential equations,we directly use the oscillatory definition,Green's formula and boundary condition of homogeneous Neumann to change the oscillatory problem of solutions to a class of systems of quasilinear parabolic equations of neutral type into the problem of which functional differential inequality haven't eventually positive solution.

针对垂直相加法无法讨论泛函偏微分方程组的强迫振动性的不足，直接利用振动的定义、Green公式以及齐次Neumann边界条件把中立型抛物微分方程组的振动问题转化为泛函微分不等式不存在最终正解的问题，然后利用最终正解的定义及上下极限得到了在齐次Neumann边界条件下判别其所有解振动或全振动的充分条件。

The existence of global weak solution for a class of generalized Ginzburg-Landau equations with an inhomogeneous boundary condition was studied. Some integral indentities of smooth solution of inhomogeneous initial boundary value problem of Ginzburg-Landau equations were deduced, by which a priori estimates of the square norm on boundary of normal derivative and the square norm of partial derivatives were obtained.

研究具非线性边界条件的一类广义Ginzburg＿Landau方程解的整体存在性·推导了Ginzburg＿Landau方程的非齐次初边值问题光滑解的几个积分恒等式，由此得到了解的法向导数在边界上的平方模以及解的平方模和导数的平方模估计；通过逼近技巧、先验估计和取极限方法证明了Ginzburg＿Landau方程的非齐次初边值问题整体弱解的存在性

The advantages and limitations of every kind of methods for calculating the failure probability is reviewed. The frist order reliability method, the second order reliability method and many kinds of boundary method have achieved remarkable success and formed nature fields of reliability. However, the precision of these methods decrease as the increase of complexity of problem. The numrical methods are versatile, except numerical intergration is only adaptable to special problems which have small number variables and regular intergral domain. Particularly, the advanced variance reduction techniques own the following character: high precision and a small amount computation. But some questions remain to study in the future because only an initial work about these techniqes is developed.

全面评述了计算失效概率各种方法的优点和局限性，其中经典的解析法包括一次可靠性方法、二次可靠性方法、一阶边界法、Vanmarcke上边界、PENT上边界和Ditlevsen二阶窄边界法，这些方法对于多设计点、变量较多且相关、密度函数不是正态以及极限状态方程较复杂的情况，其计算精度较差；而已有的数值方法却是具有较好的通用性，其中除数值积分法只对变量较少、积分域较规则的特殊问题适用外，各种数值模拟方法均具有较广的适应性，特别是各种改进的方差减小技术，精度高、计算量小，但由于其处在研究的初级阶段，还有许多问题有待于解决。

Blond children scoot around on bicycles, elderly German couples take their evening constitutionals along the waterfront and teenagers who look surprisingly like Californiasurfer dudes guide tourists through an utterly un-African extreme sports scene: sand boarding, sand sledding, sand skiing and sand sailing - none of which includes a dune lift, so all of which demand repeated uphill slogs through the sand and the inhalation of lungfuls of Namibian dust.

金发的孩子们骑着自行车飞驰而过、中年的德国夫妇沿着码头散步，像极了打扮的很花哨的加州冲浪运动员的青年们引领着游客们穿过完全没有一点非洲风格的极限运动场：沙滩冲浪，沙滩雪橇，沙滩滑雪和沙滩航行---每一个项目都离不开沙丘，而且所有的项目都会让你一次又一次地吸入纳米比亚的沙尘。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。