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In this paper, Newton iteration formula for computing normal depth and critical depth was put forward by mathematical transformation of uniform flow equation and critical flow equation of circular section tunnel. Then, the relationship between the corresponding central angle and the introduced parameters was analyzed. An approximate formula for angle was obtained according to optimal uniform approximation principle. Using this approximate formula as initial value of iteration formula, a direct formula for calculating normal depth and critical depth of circular section tunnel was established after its first iterative.

该文通过对圆形断面均匀流方程与临界流方程的数学变换，分别得到其正常水深与临界水深的牛顿迭代公式，同时，通过对正常水深与临界水深对应的中心角与引入参数之间关系的分析及数值计算，利用最优一致逼近原理分别得到了正常水深与临界水深对应中心角的近似计算式，并以此近似计算式为初值，用迭代方程进行一次迭代得到了圆形断面均匀流水深与临界流水深的直接计算公式。

The results of numerical experiments, using the four-dimensional variational data assimilation system of the nonhydrostatic mesoscale model MM5, show that: the tangent linear model and adjoint model conducted by keeping the "on-off" switches the same as the basic state, can provide a good approximation of the first-order information to the NLM perturbation and a good descent direction for the minimization procedure; switching on and off at every other time step in the Kuo cumulus parameterization scheme don"t impact the convergence rate of cost function; the existence of the switches don"t impact improvement to the MM5 model rainfall prediction because that not only specific humidity ,but also wind, temperature and pressure are assimilated into the model.

非静力中尺度数值模式MM5的四维变分资料同化系统进行的数值试验结果表明："开关"变量保持与基态一致，所构造的切向线性模式能够提供关于非线性模式扰动的一阶近似，伴随模式所计算的梯度值能够为最小化过程提供较好的下降方向；郭氏降水参数化方案中对流每隔一个积分步的交替发生并不影响目标函数最小化的收敛速度；"开关"变量的存在也不影响将风、温度、气压和比湿结合起来同化对MM5降水预报准确性的提高。

The result of the second order approximation given for me first time in the present paper leads to a theoretical m...

这种修正可以提高数值解的精度，有助于对问题获得更全面的了解，对进一步发展与完善高超音速钝头体绕流问题的数值求解方法起一定的作用。

The first order approximation solution of temperature and interface for the spherical crystal growth in the undercooled melt is solved by the asymptotic analysis method.

结果表明在球晶生长过程中依赖于界面温度变化的界面动力学显著地减缓了晶体生长的速度，与忽略界面动力学的情形比较，界面动力学显著地拟制了球晶界面生长。

The given estimated values of variables in Newton method is a crucial problem for the final solutions, the solutions of the first order approximation of the Fourier series to land surface temperature were used to the input initial given values of the Newton numerical method.

在牛顿迭代解法中，很关键也很困难的一个问题是初始值的给定，本模型中牛顿迭代的初始值是傅立叶级数对地表温度一次逼近得到的结果。

After probable damage location through MSECR, the method based on the sensitivity of orthogonality conditions gives good predictions of damage. This method overcomes the natural defect of the concept first order approximation of the ordinary sensitivity analysis method.

为克服灵敏度分析法一阶近似的本质缺陷，基于正交条件灵敏度分析法，利用MSECR对结构的损伤进行粗略定位后，给出了准确的识别结果，但这种方法的缺点是需要完备的实测振型。

The flow field around Taylor bubbles rising through stagnant liquids in vertical tubes is considered as potential flow, and the first order approximation of the control equation of gas-liquid interface and the rising velocity of Taylor bubbles are obtained.

应用势流理论分析了垂直管滞止液体中Taylor气泡周围的流场，得到了气液界面的控制方程和Taylor气泡上升速度的一阶近似结果。

Secondly, the effectiveness and limitation of the classical perturbation, such as the method of multiple scales and the Poincare-Lindstedt method, are discussed in detail through a Duffing oscillator with delayed velocity feedback. It is shown that the two perturbation methods are effective only in solving the approximate solution of the first two orders. An ambiguity or paradox will be encountered when they are used to seeking for the third or higher order approximation of solution.

其次，以一具有时滞速度反馈的Duffing系统为例，研究了经典摄动法如多尺度法，Poincaré-Lindstedt法等在求解时滞微分方程级数解时的适用性和局限性问题，指出利用这些方法只能有效求得系统的前两阶近似解，而在求系统的三次以上近似解时会出现矛盾或二义性。

In this paper,based on an improved orthogonal expansion in an clement , using the new idea of Ref.[3] ,a new error expression of n-degree Hermite finite element approximation to one-dimensional 4-degrec 2-point bounded problem and 2-degree ordinary differential problem, and then optimal order superconvergence for their first derivatives is obtained.

本文针对在改进的单元正交性估计的基础上，利用文[3]提出的新想法，得到一维四阶两点边值问题和二阶常微初值问题的n次赫米特有限元u_h∈C~1的新误差估计式，以及导数误差的最佳阶超收敛，并且两者有相同的超收敛结果。

We give left and right prediction of jump detection on basis of orthonormal polynomial. In theory analysis, we first give some theorems, then to proof the approximation, which is in a jump point detection by nonlinear prediction, can arrive one to number of samples. This result is considerable well. In the meantime, we study the approximate theory of measurement of jump point.

在理论分析中，我们首先给出了几个引理，然后证明了非线性预测法在检测单个突变点的逼近程度达到样本数的分之一，这样的结果是比较好的。

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。