导函数

Firstly, based on the method of pressure-velocity coupling introduced by SIMPLE algorithm and a revised method of solving the unsteady equation of stream function and vorticity on uniform grid, a special algorithm called primitive-variable-time-dependent approach is formed in the present study. In this algorithm the Navier-Stokes equation in primitive variable form is solved by using the time-dependent approach on non-uniform staggered grid system. The second-order accuracy finite difference is used for the first and second partial derivatives of all variables of the convective terms and diffusion terms.

首先，本文在SIMPLE算法系列处理速度与压力耦合问题的思路和均匀网格下改进的关于流函数涡量方程的数值求解方法的基础上，将非定常原始变量Navier-Stokes方程的求解推广至非等距交错网格剖分，形成了具有本文特色的原始变量时间推进方法，其中对流项和扩散项中各变量的各阶导数均采用二阶精度公式，包括温度在内的离散方程组采用ADI迭代方法求解。

Firstly, the existence of Lyapunov function with the quadratic form for linear singular systems is discussed.

然后指出对X的任何正定二次型V，它沿线性广义系统的导数V都不会是X的负定函数。

The result shows that the error in sample and quantization causes coupling error in the output of attitude in SINS.

结果表明，由于采样和量化过程中的误差，使惯导系统输出的姿态角出现了耦合误差，并提出了对采样信号进行预处理即设计滤波函数以减小采样信号失真的观点。

The emphases is the improvement to the quondam algorithm, namely, the hybrid maximum-likelihood estimation algorithm based on the information of both CP and pilot subcarriers.

重点分析了将循环前缀与导频子载波的冗余信息相结合的算法，相应地对原有算法的似然函数也进行了改进。

Padé approximation is an effective rational approximation.Using the first derivative of Gaussian function as basic wavelet,Pad conversion is used to obtain its rational fraction approximation.

采用高斯函数一阶导数作为基本小波，用Padé变换获得其有理分式逼近，利用开关电流技术实现小波滤波器可获得小波变换所需的基本小波及其膨胀小波。

In discussing the properties of reflection and refraction of fiber grating, the coupled-mode equation, envelope function, transform matrix formalism, multilayer and optical path approximation are used for describing the linear and nonlinear characteristic of optical fiber grating.

在分析光栅的反射和透射规律时，采用了耦合模式法，包络函数法，转换矩阵法，多层介质薄膜法以及光程法，这些方法虽然具有不同的数学和物理模型，但在分析光纤光栅这一特殊的波导结构时，可充分展现它的线性和非线性特性。

At the same time, the author studies the jump of the second derivative at the knots.The paper is arranged as follows.

同时，本文对插值函数的二阶导数在节点处的跳跃问题也进行了深入地分析。

The advantage of using Sigmoid function lies in the fact that it is easy to obtain it derivatives.

用Sigmoid 函数的好处是对其求导较容易。

A novel programmable generator of sigmoidal function and its derivation is proposed.

提出了一种新型的可编程S型函数及其导数的发生器电路。

Reliability of the nonlinear and complex performance function of slope stability can be got without doing derivative.

对于功能函数的非线性和复杂性，避免了有时比较繁琐的求导工作，通过编制通用程序直接计算出可靠度指标，试验点坐标和失效概率。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。